WorldWideScience

Sample records for groundwater transport simulation

  1. Neural Networks Simulation of the Transport of Contaminants in Groundwater

    Directory of Open Access Journals (Sweden)

    Enrico Zio

    2009-12-01

    Full Text Available The performance assessment of an engineered solution for the disposal of radioactive wastes is based on mathematical models of the disposal system response to predefined accidental scenarios, within a probabilistic approach to account for the involved uncertainties. As the most significant potential pathway for the return of radionuclides to the biosphere is groundwater flow, intensive computational efforts are devoted to simulating the behaviour of the groundwater system surrounding the waste deposit, for different values of its hydrogeological parameters and for different evolution scenarios. In this paper, multilayered neural networks are trained to simulate the transport of contaminants in monodimensional and bidimensional aquifers. The results obtained in two case studies indicate that the approximation errors are within the uncertainties which characterize the input data.

  2. Simulations of groundwater flow, transport, and age in Albuquerque, New Mexico, for a study of transport of anthropogenic and natural contaminants (TANC) to public-supply wells

    Science.gov (United States)

    Heywood, Charles E.

    2013-01-01

    Vulnerability to contamination from manmade and natural sources can be characterized by the groundwater-age distribution measured in a supply well and the associated implications for the source depths of the withdrawn water. Coupled groundwater flow and transport models were developed to simulate the transport of the geochemical age-tracers carbon-14, tritium, and three chlorofluorocarbon species to public-supply wells in Albuquerque, New Mexico. A separate, regional-scale simulation of transport of carbon-14 that used the flow-field computed by a previously documented regional groundwater flow model was calibrated and used to specify the initial concentrations of carbon-14 in the local-scale transport model. Observations of the concentrations of each of the five chemical species, in addition to water-level observations and measurements of intra-borehole flow within a public-supply well, were used to calibrate parameters of the local-scale groundwater flow and transport models. The calibrated groundwater flow model simulates the mixing of “young” groundwater, which entered the groundwater flow system after 1950 as recharge at the water table, with older resident groundwater that is more likely associated with natural contaminants. Complexity of the aquifer system in the zone of transport between the water table and public-supply well screens was simulated with a geostatistically generated stratigraphic realization based upon observed lithologic transitions at borehole control locations. Because effective porosity was simulated as spatially uniform, the simulated age tracers are more efficiently transported through the portions of the simulated aquifer with relatively higher simulated hydraulic conductivity. Non-pumping groundwater wells with long screens that connect aquifer intervals having different hydraulic heads can provide alternate pathways for contaminant transport that are faster than the advective transport through the aquifer material. Simulation of

  3. Metropol: A computer code for the simulation of transport of contaminants with groundwater

    International Nuclear Information System (INIS)

    Sauter, F.J.; Hassanizadeh, S.M.; Leijnse, A.; Glasbergen, P.; Slot, A.F.M.

    1990-01-01

    In this report a description is given of the computer code Metropol. This code simulates the three-dimensional flow of groundwater with varying density and the simultaneous transport of contaminants in low concentration and is based on the finite element method. The basic equations for groundwater flow and transport are described as well as the mathematical techniques used to solve these equations. Pre-processing facilities for mesh generation and post-processing facilities such as particle tracking are also discussed. This work was part of the Community Mirage project Second phase, research area Calculation tools

  4. Transient simulation and sensitivity analysis for transport of radionuclides in a saturated-unsaturated groundwater flow system

    International Nuclear Information System (INIS)

    Chen, H.H.

    1980-01-01

    Radionuclide transport by groundwater flow is an important pathway in the assessment of the environmental impact of radioactive waste disposal to the biosphere. A numerical model was developed to simulate radionuclide transport by groundwater flow and predict the radionuclide discharge rate to the biosphere. A sensitivity analysis methodology was developed to address the sensitivity of the input parameters of the radionuclide transport equation to the specified response of interest

  5. Guide to the Revised Ground-Water Flow and Heat Transport Simulator: HYDROTHERM - Version 3

    Science.gov (United States)

    Kipp, Kenneth L.; Hsieh, Paul A.; Charlton, Scott R.

    2008-01-01

    The HYDROTHERM computer program simulates multi-phase ground-water flow and associated thermal energy transport in three dimensions. It can handle high fluid pressures, up to 1 ? 109 pascals (104 atmospheres), and high temperatures, up to 1,200 degrees Celsius. This report documents the release of Version 3, which includes various additions, modifications, and corrections that have been made to the original simulator. Primary changes to the simulator include: (1) the ability to simulate unconfined ground-water flow, (2) a precipitation-recharge boundary condition, (3) a seepage-surface boundary condition at the land surface, (4) the removal of the limitation that a specified-pressure boundary also have a specified temperature, (5) a new iterative solver for the linear equations based on a generalized minimum-residual method, (6) the ability to use time- or depth-dependent functions for permeability, (7) the conversion of the program code to Fortran 90 to employ dynamic allocation of arrays, and (8) the incorporation of a graphical user interface (GUI) for input and output. The graphical user interface has been developed for defining a simulation, running the HYDROTHERM simulator interactively, and displaying the results. The combination of the graphical user interface and the HYDROTHERM simulator forms the HYDROTHERM INTERACTIVE (HTI) program. HTI can be used for two-dimensional simulations only. New features in Version 3 of the HYDROTHERM simulator have been verified using four test problems. Three problems come from the published literature and one problem was simulated by another partially saturated flow and thermal transport simulator. The test problems include: transient partially saturated vertical infiltration, transient one-dimensional horizontal infiltration, two-dimensional steady-state drainage with a seepage surface, and two-dimensional drainage with coupled heat transport. An example application to a hypothetical stratovolcano system with unconfined

  6. Calibration of a transient transport model to tritium data in streams and simulation of groundwater ages in the western Lake Taupo catchment, New Zealand

    Directory of Open Access Journals (Sweden)

    M. A. Gusyev

    2013-03-01

    Full Text Available Here we present a general approach of calibrating transient transport models to tritium concentrations in river waters developed for the MT3DMS/MODFLOW model of the western Lake Taupo catchment, New Zealand. Tritium has a known pulse-shaped input to groundwater systems due to the bomb tritium in the early 1960s and, with its radioactive half-life of 12.32 yr, allows for the determination of the groundwater age. In the transport model, the tritium input (measured in rainfall passes through the groundwater system, and the simulated tritium concentrations are matched to the measured tritium concentrations in the river and stream outlets for the Waihaha, Whanganui, Whareroa, Kuratau and Omori catchments from 2000–2007. For the Kuratau River, tritium was also measured between 1960 and 1970, which allowed us to fine-tune the transport model for the simulated bomb-peak tritium concentrations. In order to incorporate small surface water features in detail, an 80 m uniform grid cell size was selected in the steady-state MODFLOW model for the model area of 1072 km2. The groundwater flow model was first calibrated to groundwater levels and stream baseflow observations. Then, the transient tritium transport MT3DMS model was matched to the measured tritium concentrations in streams and rivers, which are the natural discharge of the groundwater system. The tritium concentrations in the rivers and streams correspond to the residence time of the water in the groundwater system (groundwater age and mixing of water with different age. The transport model output showed a good agreement with the measured tritium values. Finally, the tritium-calibrated MT3DMS model is applied to simulate groundwater ages, which are used to obtain groundwater age distributions with mean residence times (MRTs in streams and rivers for the five catchments. The effect of regional and local hydrogeology on the simulated groundwater ages is investigated by demonstrating groundwater ages

  7. Simulations of Ground-Water Flow, Transport, Age, and Particle Tracking near York, Nebraska, for a Study of Transport of Anthropogenic and Natural Contaminants (TANC) to Public-Supply Wells

    Science.gov (United States)

    Clark, Brian R.; Landon, Matthew K.; Kauffman, Leon J.; Hornberger, George Z.

    2008-01-01

    Contamination of public-supply wells has resulted in public-health threats and negative economic effects for communities that must treat contaminated water or find alternative water supplies. To investigate factors controlling vulnerability of public-supply wells to anthropogenic and natural contaminants using consistent and systematic data collected in a variety of principal aquifer settings in the United States, a study of Transport of Anthropogenic and Natural Contaminants to public-supply wells was begun in 2001 as part of the U.S. Geological Survey National Water-Quality Assessment Program. The area simulated by the ground-water flow model described in this report was selected for a study of processes influencing contaminant distribution and transport along the direction of ground-water flow towards a public-supply well in southeastern York, Nebraska. Ground-water flow is simulated for a 60-year period from September 1, 1944, to August 31, 2004. Steady-state conditions are simulated prior to September 1, 1944, and represent conditions prior to use of ground water for irrigation. Irrigation, municipal, and industrial wells were simulated using the Multi-Node Well package of the modular three-dimensional ground-water flow model code, MODFLOW-2000, which allows simulation of flow and solutes through wells that are simulated in multiple nodes or layers. Ground-water flow, age, and transport of selected tracers were simulated using the Ground-Water Transport process of MODFLOW-2000. Simulated ground-water age was compared to interpreted ground-water age in six monitoring wells in the unconfined aquifer. The tracer chlorofluorocarbon-11 was simulated directly using Ground-Water Transport for comparison with concentrations measured in six monitoring wells and one public supply well screened in the upper confined aquifer. Three alternative model simulations indicate that simulation results are highly sensitive to the distribution of multilayer well bores where leakage

  8. PHAST--a program for simulating ground-water flow, solute transport, and multicomponent geochemical reactions

    Science.gov (United States)

    Parkhurst, David L.; Kipp, Kenneth L.; Engesgaard, Peter; Charlton, Scott R.

    2004-01-01

    The computer program PHAST simulates multi-component, reactive solute transport in three-dimensional saturated ground-water flow systems. PHAST is a versatile ground-water flow and solute-transport simulator with capabilities to model a wide range of equilibrium and kinetic geochemical reactions. The flow and transport calculations are based on a modified version of HST3D that is restricted to constant fluid density and constant temperature. The geochemical reactions are simulated with the geochemical model PHREEQC, which is embedded in PHAST. PHAST is applicable to the study of natural and contaminated ground-water systems at a variety of scales ranging from laboratory experiments to local and regional field scales. PHAST can be used in studies of migration of nutrients, inorganic and organic contaminants, and radionuclides; in projects such as aquifer storage and recovery or engineered remediation; and in investigations of the natural rock-water interactions in aquifers. PHAST is not appropriate for unsaturated-zone flow, multiphase flow, density-dependent flow, or waters with high ionic strengths. A variety of boundary conditions are available in PHAST to simulate flow and transport, including specified-head, flux, and leaky conditions, as well as the special cases of rivers and wells. Chemical reactions in PHAST include (1) homogeneous equilibria using an ion-association thermodynamic model; (2) heterogeneous equilibria between the aqueous solution and minerals, gases, surface complexation sites, ion exchange sites, and solid solutions; and (3) kinetic reactions with rates that are a function of solution composition. The aqueous model (elements, chemical reactions, and equilibrium constants), minerals, gases, exchangers, surfaces, and rate expressions may be defined or modified by the user. A number of options are available to save results of simulations to output files. The data may be saved in three formats: a format suitable for viewing with a text editor; a

  9. TOUGH, Unsaturated Groundwater Transport and Heat Transport Simulation

    International Nuclear Information System (INIS)

    Pruess, K.A.; Cooper, C.; Osnes, J.D.

    1992-01-01

    1 - Description of program or function: A successor to the TOUGH program, TOUGH2 offers added capabilities and user features, including the flexibility to handle different fluid mixtures (water, water with tracer; water, CO 2 ; water, air; water, air with vapour pressure lowering, and water, hydrogen), facilities for processing of geometric data (computational grids), and an internal version control system to ensure referenceability of code applications. TOUGH (Transport of Unsaturated Groundwater and Heat) is a multi-dimensional numerical model for simulating the coupled transport of water, vapor, air, and heat in porous and fractured media. The program provides options for specifying injection or withdrawal of heat and fluids. Although primarily designed for studies of high-level nuclear waste isolation in partially saturated geological media, it should also be useful for a wider range of problems in heat and moisture transfer, and in the drying of porous materials. For example, geothermal reservoir simulation problems can be handled simply by setting the air mass function equal to zero on input. The TOUGH simulator was developed for problems involving strongly heat-driven flow. To describe these phenomena a multi-phase approach to fluid and heat flow is used, which fully accounts for the movement of gaseous and liquid phases, their transport of latent transitions between liquid and vapor. TOUGH takes account of fluid flow in both liquid and gaseous phases occurring under pressure, viscous, and gravity forces according to Darcy's law. Interference between the phases is represented by means of relative permeability functions. The code handles binary, but not Knudsen, diffusion in the gas phase and capillary and phase absorption effects for the liquid phase. Heat transport occurs by means of conduction with thermal conductivity dependent on water saturation, convection, and binary diffusion, which includes both sensible and latent heat. 2 - Method of solution: All

  10. Simulation of ground-water flow and solute transport in the Glen Canyon aquifer, East-Central Utah

    Science.gov (United States)

    Freethey, Geoffrey W.; Stolp, Bernard J.

    2010-01-01

    The extraction of methane from coal beds in the Ferron coal trend in central Utah started in the mid-1980s. Beginning in 1994, water from the extraction process was pressure injected into the Glen Canyon aquifer. The lateral extent of the aquifer that could be affected by injection is about 7,600 square miles. To address regional-scale effects of injection over a decadal time frame, a conceptual model of ground-water movement and transport of dissolved solids was formulated. A numerical model that incorporates aquifer concepts was then constructed and used to simulate injection.The Glen Canyon aquifer within the study area is conceptualized in two parts—an active area of ground-water flow and solute transport that exists between recharge areas in the San Rafael Swell and Desert, Waterpocket Fold, and Henry Mountains and discharge locations along the Muddy, Dirty Devil, San Rafael, and Green Rivers. An area of little or negligible ground-water flow exists north of Price, Utah, and beneath the Wasatch Plateau. Pressurized injection of coal-bed methane production water occurs in this area where dissolved-solids concentrations can be more than 100,000 milligrams per liter. Injection has the potential to increase hydrologic interaction with the active flow area, where dissolved-solids concentrations are generally less than 3,000 milligrams per liter.Pressurized injection of coal-bed methane production water in 1994 initiated a net addition of flow and mass of solutes into the Glen Canyon aquifer. To better understand the regional scale hydrologic interaction between the two areas of the Glen Canyon aquifer, pressurized injection was numerically simulated. Data constraints precluded development of a fully calibrated simulation; instead, an uncalibrated model was constructed that is a plausible representation of the conceptual flow and solute-transport processes. The amount of injected water over the 36-year simulation period is about 25,000 acre-feet. As a result

  11. PHAST Version 2-A Program for Simulating Groundwater Flow, Solute Transport, and Multicomponent Geochemical Reactions

    Science.gov (United States)

    Parkhurst, David L.; Kipp, Kenneth L.; Charlton, Scott R.

    2010-01-01

    The computer program PHAST (PHREEQC And HST3D) simulates multicomponent, reactive solute transport in three-dimensional saturated groundwater flow systems. PHAST is a versatile groundwater flow and solute-transport simulator with capabilities to model a wide range of equilibrium and kinetic geochemical reactions. The flow and transport calculations are based on a modified version of HST3D that is restricted to constant fluid density and constant temperature. The geochemical reactions are simulated with the geochemical model PHREEQC, which is embedded in PHAST. Major enhancements in PHAST Version 2 allow spatial data to be defined in a combination of map and grid coordinate systems, independent of a specific model grid (without node-by-node input). At run time, aquifer properties are interpolated from the spatial data to the model grid; regridding requires only redefinition of the grid without modification of the spatial data. PHAST is applicable to the study of natural and contaminated groundwater systems at a variety of scales ranging from laboratory experiments to local and regional field scales. PHAST can be used in studies of migration of nutrients, inorganic and organic contaminants, and radionuclides; in projects such as aquifer storage and recovery or engineered remediation; and in investigations of the natural rock/water interactions in aquifers. PHAST is not appropriate for unsaturated-zone flow, multiphase flow, or density-dependent flow. A variety of boundary conditions are available in PHAST to simulate flow and transport, including specified-head, flux (specified-flux), and leaky (head-dependent) conditions, as well as the special cases of rivers, drains, and wells. Chemical reactions in PHAST include (1) homogeneous equilibria using an ion-association or Pitzer specific interaction thermodynamic model; (2) heterogeneous equilibria between the aqueous solution and minerals, ion exchange sites, surface complexation sites, solid solutions, and gases; and

  12. Novel patch modelling method for efficient simulation and prediction uncertainty analysis of multi-scale groundwater flow and transport processes

    Science.gov (United States)

    Sreekanth, J.; Moore, Catherine

    2018-04-01

    The application of global sensitivity and uncertainty analysis techniques to groundwater models of deep sedimentary basins are typically challenged by large computational burdens combined with associated numerical stability issues. The highly parameterized approaches required for exploring the predictive uncertainty associated with the heterogeneous hydraulic characteristics of multiple aquifers and aquitards in these sedimentary basins exacerbate these issues. A novel Patch Modelling Methodology is proposed for improving the computational feasibility of stochastic modelling analysis of large-scale and complex groundwater models. The method incorporates a nested groundwater modelling framework that enables efficient simulation of groundwater flow and transport across multiple spatial and temporal scales. The method also allows different processes to be simulated within different model scales. Existing nested model methodologies are extended by employing 'joining predictions' for extrapolating prediction-salient information from one model scale to the next. This establishes a feedback mechanism supporting the transfer of information from child models to parent models as well as parent models to child models in a computationally efficient manner. This feedback mechanism is simple and flexible and ensures that while the salient small scale features influencing larger scale prediction are transferred back to the larger scale, this does not require the live coupling of models. This method allows the modelling of multiple groundwater flow and transport processes using separate groundwater models that are built for the appropriate spatial and temporal scales, within a stochastic framework, while also removing the computational burden associated with live model coupling. The utility of the method is demonstrated by application to an actual large scale aquifer injection scheme in Australia.

  13. Development of one-dimensional computational fluid dynamics code 'GFLOW' for groundwater flow and contaminant transport analysis

    International Nuclear Information System (INIS)

    Rahatgaonkar, P. S.; Datta, D.; Malhotra, P. K.; Ghadge, S. G.

    2012-01-01

    Prediction of groundwater movement and contaminant transport in soil is an important problem in many branches of science and engineering. This includes groundwater hydrology, environmental engineering, soil science, agricultural engineering and also nuclear engineering. Specifically, in nuclear engineering it is applicable in the design of spent fuel storage pools and waste management sites in the nuclear power plants. Ground water modeling involves the simulation of flow and contaminant transport by groundwater flow. In the context of contaminated soil and groundwater system, numerical simulations are typically used to demonstrate compliance with regulatory standard. A one-dimensional Computational Fluid Dynamics code GFLOW had been developed based on the Finite Difference Method for simulating groundwater flow and contaminant transport through saturated and unsaturated soil. The code is validated with the analytical model and the benchmarking cases available in the literature. (authors)

  14. Simulating Salt Movement using a Coupled Salinity Transport Model in a Variably Saturated Agricultural Groundwater System

    Science.gov (United States)

    Tavakoli Kivi, S.; Bailey, R. T.; Gates, T. K.

    2017-12-01

    Salinization is one of the major concerns in irrigated agricultural fields. Increasing salinity concentrations are due principally to a high water table that results from excessive irrigation, canal seepage, and a lack of efficient drainage systems, and lead to decreasing crop yield. High groundwater salinity loading to nearby river systems also impacts downstream areas, with saline river water diverted for application on irrigated fields. To assess the different strategies for salt remediation, we present a reactive transport model (UZF-RT3D) coupled with a salinity equilibrium chemistry module for simulating the fate and transport of salt ions in a variably-saturated agricultural groundwater system. The developed model accounts not for advection, dispersion, nitrogen and sulfur cycling, oxidation-reduction, sorption, complexation, ion exchange, and precipitation/dissolution of salt minerals. The model is applied to a 500 km2 region within the Lower Arkansas River Valley (LARV) in southeastern Colorado, an area acutely affected by salinization in the past few decades. The model is tested against salt ion concentrations in the saturated zone, total dissolved solid concentrations in the unsaturated zone, and salt groundwater loading to the Arkansas River. The model now can be used to investigate salinity remediation strategies.

  15. Simulating the reactive transport of nitrogen species in a regional irrigated agricultural groundwater system

    Science.gov (United States)

    Bailey, R. T.; Gates, T. K.

    2011-12-01

    The fate and transport of nitrogen (N) species in irrigated agricultural groundwater systems is governed by irrigation patterns, cultivation practices, aquifer-surface water exchanges, and chemical reactions such as oxidation-reduction, volatilization, and sorption, as well as the presence of dissolved oxygen (O2). We present results of applying the newly-developed numerical model RT3D-AG to a 50,400-ha regional study site within the Lower Arkansas River Valley in southeastern Colorado, where elevated concentrations of NO3 have been observed in both groundwater and surface water during the recent decade. Furthermore, NO3 has a strong influence on the fate and transport of other contaminants in the aquifer system such as selenium (Se) through inhibition of reduction of dissolved Se as well as oxidation of precipitate Se from outcropped and bedrock shale. RT3D-AG, developed by appending the multi-species reactive transport finite-difference model RT3D with modular packages that account for variably-saturated transport, the cycling of carbon (C) and N, and the fate and transport of O2 within the soil and aquifer system, simulates organic C and organic N decomposition and mineralization, oxidation-reduction reactions, and sorption. System sources/sinks consist of applied fertilizer and manure; crop uptake of ammonium (NH4) and NO3 during the growing season; mass of O2, NO3, and NH4 associated with irrigation water and canal seepage; mass of O2, NO3, and NH4 transferred to canals and the Arkansas River from the aquifer; and dead root mass and after-harvest stover mass incorporated into the soil organic matter at the end of the growing season. Chemical reactions are simulated using first-order Monod kinetics, wherein the rate of reaction is dependent on the concentration of the reactants as well as temperature and water content of the soil. Fertilizer and manure application timing and loading, mass of seasonal crop uptake, and end-of-season root mass and stover mass are

  16. Site scale groundwater flow in Olkiluoto - complementary simulations

    International Nuclear Information System (INIS)

    Loefman, J.

    2000-06-01

    This work comprises of the complementary simulations to the previous groundwater flow analysis at the Olkiluoto site. The objective is to study the effects of flow porosity, conceptual model for solute transport, fracture zones, land uplift and initial conditions on the results. The numerical simulations are carried out up to 10000 years into the future employing the same modelling approach and site-specific flow and transport model as in the previous work except for the differences in the case descriptions. The result quantities considered are the salinity and the driving force in the vicinity of the repository. The salinity field and the driving force are sensitive to the flow porosity and the conceptual model for solute transport. Ten-fold flow porosity and the dual-porosity approach retard the transport of solutes in the bedrock resulting in brackish groundwater conditions at the repository at 10000 years A.P. (in the previous work the groundwater in the repository turned into fresh). The higher driving forces can be attributed to the higher concentration gradients resulting from the opposite effects of the land uplift, which pushes fresh water deeper and deeper into the bedrock, and the higher flow porosity and the dual-porosity model, which retard the transport of solutes. The cases computed (unrealistically) without fracture zones and postglacial land uplift show that they both have effect on the results and can not be ignored in the coupled and transient groundwater flow analyses. The salinity field and the driving force are also sensitive to the initial salinity field especially at the beginning during the first 500 years A.P. The sensitivity will, however, diminish as soon as fresh water dilutes brackish and saline water and decreases the concentration gradients. Fresh water conditions result in also a steady state for the driving force in the repository area. (orig.)

  17. Limitations of sorption isotherms on modeling groundwater contaminant transport

    International Nuclear Information System (INIS)

    Silva, Eduardo Figueira da

    2007-01-01

    Design and safety assessment of radioactive waste repositories, as well as remediation of radionuclide contaminated groundwater require the development of models capable of accurately predicting trace element fate and transport. Adsorption of trace radionuclides onto soils and groundwater is an important mechanism controlling near- and far- field transport. Although surface complexation models (SCMs) can better describe the adsorption mechanisms of most radionuclides onto mineral surfaces by directly accounting for variability of system properties and mineral surface properties, isotherms are still used to model contaminant transport in groundwater, despite the much higher system dependence. The present work investigates differences between transport model results based on these two approaches for adsorption modeling. A finite element transport model is used for the isotherm model, whereas the computer program PHREEQC is used for the SCM approach. Both models are calibrated for a batch experiment, and one-dimensional transport is simulated using the calibrated parameters. At the lower injected concentrations there are large discrepancies between SCM and isotherm transport predictions, with the SCM presenting much longer tails on the breakthrough curves. Isotherms may also provide non-conservative results for time to breakthrough and for maximum concentration in a contamination plume. Isotherm models are shown not to be robust enough to predict transport behavior of some trace elements, thus discouraging their use. The results also illustrate the promise of the SCM modeling approach in safety assessment and environmental remediation applications, also suggesting that independent batch sorption measurements can be used, within the framework of the SCM, to produce a more versatile and realistic groundwater transport model for radionuclides which is capable of accounting more accurately for temporal and spatial variations in geochemical conditions. (author)

  18. Simulation of Groundwater Flow, Denpasar-Tabanan Groundwater Basin, Bali Province

    Directory of Open Access Journals (Sweden)

    Heryadi Tirtomihardjo

    2014-06-01

    Full Text Available DOI: 10.17014/ijog.v6i3.123Due to the complex structure of the aquifer systems and its hydrogeological units related with the space in which groundwater occurs, groundwater flows were calculated in three-dimensional method (3D Calculation. The geometrical descritization and iteration procedures were based on an integrated finite difference method. In this paper, all figures and graphs represent the results of the calibrated model. Hence, the model results were simulated by using the actual input data which were calibrated during the simulation runs. Groundwater flow simulation of the model area of the Denpasar-Tabanan Groundwater Basin (Denpasar-Tabanan GB comprises steady state run, transient runs using groundwater abstraction in the period of 1989 (Qabs-1989 and period of 2009 (Qabs-2009, and prognosis run as well. Simulation results show, in general, the differences of calculated groundwater heads and observed groundwater heads at steady and transient states (Qabs-1989 and Qabs-2009 are relatively small. So, the groundwater heads situation simulated by the prognosis run (scenario Qabs-2012 are considerably valid and can properly be used for controlling the plan of groundwater utilization in Denpasar-Tabanan GB.

  19. Theoretical background and user's manual for the computer code on groundwater flow and radionuclide transport calculation in porous rock

    International Nuclear Information System (INIS)

    Shirakawa, Toshihiko; Hatanaka, Koichiro

    2001-11-01

    In order to document a basic manual about input data, output data, execution of computer code on groundwater flow and radionuclide transport calculation in heterogeneous porous rock, we investigated the theoretical background about geostatistical computer codes and the user's manual for the computer code on groundwater flow and radionuclide transport which calculates water flow in three dimension, the path of moving radionuclide, and one dimensional radionuclide migration. In this report, based on above investigation we describe the geostatistical background about simulating heterogeneous permeability field. And we describe construction of files, input and output data, a example of calculating of the programs which simulates heterogeneous permeability field, and calculates groundwater flow and radionuclide transport. Therefore, we can document a manual by investigating the theoretical background about geostatistical computer codes and the user's manual for the computer code on groundwater flow and radionuclide transport calculation. And we can model heterogeneous porous rock and analyze groundwater flow and radionuclide transport by utilizing the information from this report. (author)

  20. Transient groundwater chemistry near a river: Effects on U(VI) transport in laboratory column experiments

    Science.gov (United States)

    Yin, Jun; Haggerty, Roy; Stoliker, Deborah L.; Kent, Douglas B.; Istok, Jonathan D.; Greskowiak, Janek; Zachara, John M.

    2011-01-01

    In the 300 Area of a U(VI)-contaminated aquifer at Hanford, Washington, USA, inorganic carbon and major cations, which have large impacts on U(VI) transport, change on an hourly and seasonal basis near the Columbia River. Batch and column experiments were conducted to investigate the factors controlling U(VI) adsorption/desorption by changing chemical conditions over time. Low alkalinity and low Ca concentrations (Columbia River water) enhanced adsorption and reduced aqueous concentrations. Conversely, high alkalinity and high Ca concentrations (Hanford groundwater) reduced adsorption and increased aqueous concentrations of U(VI). An equilibrium surface complexation model calibrated using laboratory batch experiments accounted for the decrease in U(VI) adsorption observed with increasing (bi)carbonate concentrations and other aqueous chemical conditions. In the column experiment, alternating pulses of river and groundwater caused swings in aqueous U(VI) concentration. A multispecies multirate surface complexation reactive transport model simulated most of the major U(VI) changes in two column experiments. The modeling results also indicated that U(VI) transport in the studied sediment could be simulated by using a single kinetic rate without loss of accuracy in the simulations. Moreover, the capability of the model to predict U(VI) transport in Hanford groundwater under transient chemical conditions depends significantly on the knowledge of real-time change of local groundwater chemistry.

  1. Grand challenge problems in environmental modeling and remediation: Groundwater contaminant transport. Final project report 1998

    International Nuclear Information System (INIS)

    1998-04-01

    The over-reaching goal of the Groundwater Grand Challenge component of the Partnership in Computational Science (PICS) was to develop and establish the massively parallel approach for the description of groundwater flow and transport and to address the problem of uncertainties in the data and its interpretation. This necessitated the development of innovative algorithms and the implementation of massively parallel computational tools to provide a suite of simulators for groundwater flow and transport in heterogeneous media. This report summarizes the activities and deliverables of the Groundwater Grand Challenge project funded through the High Performance Computing grand challenge program of the Department of Energy from 1995 through 1997

  2. Numerical simulation of groundwater flow in LILW Repository site:I. Groundwater flow modeling

    Energy Technology Data Exchange (ETDEWEB)

    Park, Koung Woo; Ji, Sung Hoon; Kim, Chun Soo; Kim, Kyoung Su [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Kim, Ji Yeon [Korea Hydro and Nuclear Power Co. Ltd., Seoul (Korea, Republic of)

    2008-12-15

    Based on the site characterization works in a low and intermediate level waste (LILW) repository site, the numerical simulations for groundwater flow were carried out in order to understand the groundwater flow system of repository site. To accomplish the groundwater flow modeling in the repository site, the discrete fracture network (DFN) model was constructed using the characteristics of fracture zones and background fractures. At result, the total 10 different hydraulic conductivity(K) fields were obtained from DFN model stochastically and K distributions of constructed mesh were inputted into the 10 cases of groundwater flow simulations in FEFLOW. From the total 10 numerical simulation results, the simulated groundwater levels were strongly governed by topography and the groundwater fluxes were governed by locally existed high permeable fracture zones in repository depth. Especially, the groundwater table was predicted to have several tens meters below the groundwater table compared with the undisturbed condition around disposal silo after construction of underground facilities. After closure of disposal facilities, the groundwater level would be almost recovered within 1 year and have a tendency to keep a steady state of groundwater level in 2 year.

  3. The effect of modeled recharge distribution on simulated groundwater availability and capture.

    Science.gov (United States)

    Tillman, F D; Pool, D R; Leake, S A

    2015-01-01

    Simulating groundwater flow in basin-fill aquifers of the semiarid southwestern United States commonly requires decisions about how to distribute aquifer recharge. Precipitation can recharge basin-fill aquifers by direct infiltration and transport through faults and fractures in the high-elevation areas, by flowing overland through high-elevation areas to infiltrate at basin-fill margins along mountain fronts, by flowing overland to infiltrate along ephemeral channels that often traverse basins in the area, or by some combination of these processes. The importance of accurately simulating recharge distributions is a current topic of discussion among hydrologists and water managers in the region, but no comparative study has been performed to analyze the effects of different recharge distributions on groundwater simulations. This study investigates the importance of the distribution of aquifer recharge in simulating regional groundwater flow in basin-fill aquifers by calibrating a groundwater-flow model to four different recharge distributions, all with the same total amount of recharge. Similarities are seen in results from steady-state models for optimized hydraulic conductivity values, fit of simulated to observed hydraulic heads, and composite scaled sensitivities of conductivity parameter zones. Transient simulations with hypothetical storage properties and pumping rates produce similar capture rates and storage change results, but differences are noted in the rate of drawdown at some well locations owing to the differences in optimized hydraulic conductivity. Depending on whether the purpose of the groundwater model is to simulate changes in groundwater levels or changes in storage and capture, the distribution of aquifer recharge may or may not be of primary importance. Published 2014. This article is a U.S. Government work and is in the public domain in the USA.

  4. Numerical simulation of alteration of sodium bentonite by diffusion of ionic groundwater components

    International Nuclear Information System (INIS)

    Jacobsen, J.S.; Carnahan, C.L.

    1987-12-01

    Experiments measuring the movement of trace amounts of radionuclides through compacted bentonite have typically used unaltered bentonite. Models based on experiments such as these may not lead to accurate predictions of the migration through altered or partially altered bentonite of radionuclides that undergo ion exchange. To address this problem, we have modified an existing transport code to include ion exchange and aqueous complexation reactions. The code is thus able to simulate the diffusion of major ionic groundwater components through bentonite and reactions between the bentonite and groundwater. Numerical simulations have been made to investigate the conversion of sodium bentonite to calcium bentonite for a reference groundwater characteristic of deep granitic formations. 20 refs., 2 figs., 2 tabs

  5. Modelling pesticide transport in a shallow groundwater catchment using tritium and helium-3 data

    International Nuclear Information System (INIS)

    Åkesson, Maria; Bendz, David; Carlsson, Christel; Sparrenbom, Charlotte J.; Kreuger, Jenny

    2014-01-01

    Highlights: • A catchment-scale groundwater model is calibrated against 3 H and 3 He data. • Transport of pesticides is modelled using site-specific sorption and degradation data. • Breakthrough of pesticides with low K d -values is successfully simulated. • Model constraints are an effect of a simplified system conceptualisation. - Abstract: Using tritium and helium-3 data for calibration, a 2-D transport model was set up to explain the occurrence of bentazone, dichlorprop, glyphosate, isoproturon, MCPA and metamitron in a small groundwater catchment in southern Sweden. The model was parameterised with site-specific degradation and sorption data to enable transport simulations. Local climatological data and a 21-year record of agricultural pesticide use within the study area were used as boundary conditions. Model output was evaluated against a 7-year long pesticide monitoring data-series from two monitoring wells within the study area. The model successfully predicts observed breakthrough of bentazone, dichlorprop, isoproturon and MCPA. However, it fails to simulate observed occurrences of glyphosate and metamitron. Glyphosate and metamitron exhibit relatively high sorption potential, and their occurrence is suggested to be the result of non-equilibrium preferential flow paths which the model cannot reproduce due the conceptualisation of the system as homogenous and isotropic. The results indicate a promising methodological approach applicable to groundwater contamination risk assessment, and demonstrate the potential for transport model calibration by means of tritium and helium-3 data. Main constraints of the study relate to the relatively simple system conceptualisation, indicating a need for further consideration of physical and chemical heterogeneity

  6. Simulating groundwater-induced sewer flooding

    Science.gov (United States)

    Mijic, A.; Mansour, M.; Stanic, M.; Jackson, C. R.

    2016-12-01

    During the last decade, Chalk catchments of southern England experienced severe groundwater flooding. High groundwater levels resulted in the groundwater ingress into the sewer network that led to restricted toilet use and the overflow of diluted, but untreated sewage to road surfaces, rivers and water courses. In response to these events the water and sewerage company Thames Water Utilities Ltd (TWUL) had to allocate significant funds to mitigate the impacts. It was estimated that approximately £19m was spent responding to the extreme wet weather of 2013-14, along with the use of a fleet of over 100 tankers. However, the magnitude of the event was so large that these efforts could not stop the discharge of sewage to the environment. This work presents the analysis of the risk of groundwater-induced sewer flooding within the Chalk catchment of the River Lambourn, Berkshire. A spatially distributed groundwater model was used to assess historic groundwater flood risk and the potential impacts of changes in future climate. We then linked this model to an urban groundwater model to enable us to simulate groundwater-sewer interaction in detail. The modelling setup was used to identify relationships between infiltration into sewers and groundwater levels at specific points on TWUL's sewer network, and to estimate historic and future groundwater flood risk, and how this varies across the catchment. The study showed the significance of understanding the impact of groundwater on the urban water systems, and producing information that can inform a water company's response to groundwater flood risk, their decision making process and their asset management planning. However, the knowledge gained through integrated modelling of groundwater-sewer interactions has highlighted limitations of existing approaches for the simulation of these coupled systems. We conclude this work with number of recommendations about how to improve such hydrological/sewer analysis.

  7. Revised conceptualization of the North China Basin groundwater flow system: Groundwater age, heat and flow simulations

    Science.gov (United States)

    Cao, Guoliang; Han, Dongmei; Currell, Matthew J.; Zheng, Chunmiao

    2016-09-01

    Groundwater flow in deep sedimentary basins results from complex evolution processes on geological timescales. Groundwater flow systems conceptualized according to topography and/or groundwater table configuration generally assume a near-equilibrium state with the modern landscape. However, the time to reach such a steady state, and more generally the timescales of groundwater flow system evolution are key considerations for large sedimentary basins. This is true in the North China Basin (NCB), which has been studied for many years due to its importance as a groundwater supply. Despite many years of study, there remain contradictions between the generally accepted conceptual model of regional flow, and environmental tracer data. We seek to reconcile these contractions by conducting simulations of groundwater flow, age and heat transport in a three dimensional model, using an alternative conceptual model, based on geological, thermal, isotope and historical data. We infer flow patterns under modern hydraulic conditions using this new model and present the theoretical maximum groundwater ages under such a flow regime. The model results show that in contrast to previously accepted conceptualizations, most groundwater is discharged in the vicinity of the break-in-slope of topography at the boundary between the piedmont and central plain. Groundwater discharge to the ocean is in contrast small, and in general there are low rates of active flow in the eastern parts of the basin below the central and coastal plain. This conceptualization is more compatible with geochemical and geothermal data than the previous model. Simulated maximum groundwater ages of ∼1 Myrs below the central and coastal plain indicate that residual groundwater may be retained in the deep parts of the basin since being recharged during the last glacial period or earlier. The groundwater flow system has therefore probably not reached a new equilibrium state with modern-day hydraulic conditions. The

  8. Coupling ANIMO and MT3DMS for 3D regional-scale modeling of nutrient transport in soil and groundwater

    Science.gov (United States)

    Janssen, G.; Del Val Alonso, L.; Groenendijk, P.; Griffioen, J.

    2012-12-01

    We developed an on-line coupling between the 1D/quasi-2D nutrient transport model ANIMO and the 3D groundwater transport model code MT3DMS. ANIMO is a detailed, process-oriented model code for the simulation of nitrate leaching to groundwater, N- and P-loads on surface waters and emissions of greenhouse gasses. It is the leading nutrient fate and transport code in the Netherlands where it is used primarily for the evaluation of fertilization related legislation. In addition, the code is applied frequently in international research projects. MT3DMS is probably the most commonly used groundwater solute transport package worldwide. The on-line model coupling ANIMO-MT3DMS combines the state-of-the-art descriptions of the biogeochemical cycles in ANIMO with the advantages of using a 3D approach for the transport through the saturated domain. These advantages include accounting for regional lateral transport, considering groundwater-surface water interactions more explicitly, and the possibility of using MODFLOW to obtain the flow fields. An additional merit of the on-line coupling concept is that it preserves feedbacks between the saturated and unsaturated zone. We tested ANIMO-MT3DMS by simulating nutrient transport for the period 1970-2007 in a Dutch agricultural polder catchment covering an area of 118 km2. The transient groundwater flow field had a temporal resolution of one day and was calculated with MODFLOW-MetaSWAP. The horizontal resolution of the model grid was 100x100m and consisted of 25 layers of varying thickness. To keep computation times manageable, we prepared MT3DMS for parallel computing, which in itself is a relevant development for a large community of groundwater transport modelers. For the parameterization of the soil, we applied a standard classification approach, representing the area by 60 units with unique combinations of soil type, land use and geohydrological setting. For the geochemical parameterization of the deeper subsurface, however, we

  9. SEAWAT-based simulation of axisymmetric heat transport.

    Science.gov (United States)

    Vandenbohede, Alexander; Louwyck, Andy; Vlamynck, Nele

    2014-01-01

    Simulation of heat transport has its applications in geothermal exploitation of aquifers and the analysis of temperature dependent chemical reactions. Under homogeneous conditions and in the absence of a regional hydraulic gradient, groundwater flow and heat transport from or to a well exhibit radial symmetry, and governing equations are reduced by one dimension (1D) which increases computational efficiency importantly. Solute transport codes can simulate heat transport and input parameters may be modified such that the Cartesian geometry can handle radial flow. In this article, SEAWAT is evaluated as simulator for heat transport under radial flow conditions. The 1971, 1D analytical solution of Gelhar and Collins is used to compare axisymmetric transport with retardation (i.e., as a result of thermal equilibrium between fluid and solid) and a large diffusion (conduction). It is shown that an axisymmetric simulation compares well with a fully three dimensional (3D) simulation of an aquifer thermal energy storage systems. The influence of grid discretization, solver parameters, and advection solution is illustrated. Because of the high diffusion to simulate conduction, convergence criterion for heat transport must be set much smaller (10(-10) ) than for solute transport (10(-6) ). Grid discretization should be considered carefully, in particular the subdivision of the screen interval. On the other hand, different methods to calculate the pumping or injection rate distribution over different nodes of a multilayer well lead to small differences only. © 2013, National Ground Water Association.

  10. Simulation of methyl tert-butyl ether (MTBE) transport to ground water from immobile sources of gasoline in the vadose zone

    Science.gov (United States)

    Lahvis, M.A.; Rehmann, L.C.

    1999-01-01

    The mathematical model, R-UNSAT, developed to simulate the transport of benzene and MTBE in representative sand and clay hydrogeologic systems was evaluated. The effects on groundwater were simulated for small, chronic-, and single-volume releases of gasoline trapped in unsaturated soil. Hydrocarbon biodegradation was simulated by using a dual Monod-type kinetics model that includes oxygen and the reactive constituents. MTBE was assumed to be non-reactive. For MTBE, infiltration had the greatest effect on transport to groundwater. Infiltration also affected mass losses of MTBE to the atmosphere, particularly, in fine-grained soils. Depth to groundwater and soil type primarily affected travel times of MTBE to groundwater, but could affect mass-loading rates to groundwater if infiltration is insignificant. For benzene, transport to groundwater was significant only if the depth to the water table was groundwater were generally smaller for benzene than for MTBE by more than two orders of magnitude. Thus, water that recharges an aquifer beneath a spill can be enriched in MTBE relative to benzene when compared to the composition of water in equilibrium with gasoline.

  11. Hydrology and numerical simulation of groundwater movement and heat transport in Snake Valley and surrounding areas, Juab, Miller, and Beaver Counties, Utah, and White Pine and Lincoln Counties, Nevada

    Science.gov (United States)

    Masbruch, Melissa D.; Gardner, Philip M.; Brooks, Lynette E.

    2014-01-01

    Snake Valley and surrounding areas, along the Utah-Nevada state border, are part of the Great Basin carbonate and alluvial aquifer system. The groundwater system in the study area consists of water in unconsolidated deposits in basins and water in consolidated rock underlying the basins and in the adjacent mountain blocks. Most recharge occurs from precipitation on the mountain blocks and most discharge occurs from the lower altitude basin-fill deposits mainly as evapotranspiration, springflow, and well withdrawals.The Snake Valley area regional groundwater system was simulated using a three-dimensional model incorporating both groundwater flow and heat transport. The model was constructed with MODFLOW-2000, a version of the U.S. Geological Survey’s groundwater flow model, and MT3DMS, a transport model that simulates advection, dispersion, and chemical reactions of solutes or heat in groundwater systems. Observations of groundwater discharge by evapotranspiration, springflow, mountain stream base flow, and well withdrawals; groundwater-level altitudes; and groundwater temperatures were used to calibrate the model. Parameter values estimated by regression analyses were reasonable and within the range of expected values.This study represents one of the first regional modeling efforts to include calibration to groundwater temperature data. The inclusion of temperature observations reduced parameter uncertainty, in some cases quite significantly, over using just water-level altitude and discharge observations. Of the 39 parameters used to simulate horizontal hydraulic conductivity, uncertainty on 11 of these parameters was reduced to one order of magnitude or less. Other significant reductions in parameter uncertainty occurred in parameters representing the vertical anisotropy ratio, drain and river conductance, recharge rates, and well withdrawal rates.The model provides a good representation of the groundwater system. Simulated water-level altitudes range over

  12. 3D modeling of groundwater heat transport in the shallow Westliches Leibnitzer Feld aquifer, Austria

    Science.gov (United States)

    Rock, Gerhard; Kupfersberger, Hans

    2018-02-01

    For the shallow Westliches Leibnitzer feld aquifer (45 km2) we applied the recently developed methodology by Kupfersberger et al. (2017a) to derive the thermal upper boundary for a 3D heat transport model from observed air temperatures. We distinguished between land uses of grass and agriculture, sealed surfaces, forest and water bodies. To represent the heat flux from heated buildings and the mixture between different land surfaces in urban areas we ran the 1D vertical heat conduction module SoilTemp which is coupled to the heat transport model (using FEFLOW) on a time step basis. Over a simulation period of 23 years the comparison between measured and observed groundwater temperatures yielded NSE values ranging from 0.41 to 0.92 including readings at different depths. The model results showed that the thermal input signals lead to distinctly different vertical groundwater temperature distributions. To overcome the influence of specific warm or cold years we introduced the computation of an annual averaged groundwater temperature profile. With respect to the use of groundwater cooling or heating facilities we evaluated the application of vertically averaged statistical groundwater temperature distributions compared to the use of temperature distributions at selected dates. We concluded that the heat transport model serves well as an aquifer scale management tool to optimize the use of the shallow subsurface for thermal purposes and to analyze the impacts of corresponding measures on groundwater temperatures.

  13. Software for modelling groundwater transport and contaminant migration

    International Nuclear Information System (INIS)

    Gishkelyuk, I.A.

    2008-01-01

    Facilities of modern software for modeling of groundwater transport and process of contaminant distribution are considered. Advantages of their application are discussed. The comparative analysis of mathematical modeling software of 'Groundwater modeling system' and 'Earth Science Module' from 'COMSOL Multiphysics' is carried out. (authors)

  14. Recent Approaches to Modeling Transport of Mercury in Surface Water and Groundwater - Case Study in Upper East Fork Poplar Creek, Oak Ridge, TN - 13349

    International Nuclear Information System (INIS)

    Bostick, Kent; Daniel, Anamary; Tachiev, Georgio; Malek-Mohammadi, Siamak

    2013-01-01

    In this case study, groundwater/surface water modeling was used to determine efficacy of stabilization in place with hydrologic isolation for remediation of mercury contaminated areas in the Upper East Fork Poplar Creek (UEFPC) Watershed in Oak Ridge, TN. The modeling simulates the potential for mercury in soil to contaminate groundwater above industrial use risk standards and to contribute to surface water contamination. The modeling approach is unique in that it couples watershed hydrology with the total mercury transport and provides a tool for analysis of changes in mercury load related to daily precipitation, evaporation, and runoff from storms. The model also allows for simulation of colloidal transport of total mercury in surface water. Previous models for the watershed only simulated average yearly conditions and dissolved concentrations that are not sufficient for predicting mercury flux under variable flow conditions that control colloidal transport of mercury in the watershed. The transport of mercury from groundwater to surface water from mercury sources identified from information in the Oak Ridge Environmental Information System was simulated using a watershed scale model calibrated to match observed daily creek flow, total suspended solids and mercury fluxes. Mercury sources at the former Building 81-10 area, where mercury was previously retorted, were modeled using a telescopic refined mesh with boundary conditions extracted from the watershed model. Modeling on a watershed scale indicated that only source excavation for soils/sediment in the vicinity of UEFPC had any effect on mercury flux in surface water. The simulations showed that colloidal transport contributed 85 percent of the total mercury flux leaving the UEFPC watershed under high flow conditions. Simulation of dissolved mercury transport from liquid elemental mercury and adsorbed sources in soil at former Building 81-10 indicated that dissolved concentrations are orders of magnitude

  15. Recent Approaches to Modeling Transport of Mercury in Surface Water and Groundwater - Case Study in Upper East Fork Poplar Creek, Oak Ridge, TN - 13349

    Energy Technology Data Exchange (ETDEWEB)

    Bostick, Kent; Daniel, Anamary [Professional Project Services, Inc., Bethel Valley Road, Oak Ridge, TN, 37922 (United States); Tachiev, Georgio [Florida International University, Applied Research Center 10555 W. Flagler St., EC 2100 Miami Florida 33174 (United States); Malek-Mohammadi, Siamak [Bradley University, 413A Jobst Hall, Preoria, IL 61625 (United States)

    2013-07-01

    In this case study, groundwater/surface water modeling was used to determine efficacy of stabilization in place with hydrologic isolation for remediation of mercury contaminated areas in the Upper East Fork Poplar Creek (UEFPC) Watershed in Oak Ridge, TN. The modeling simulates the potential for mercury in soil to contaminate groundwater above industrial use risk standards and to contribute to surface water contamination. The modeling approach is unique in that it couples watershed hydrology with the total mercury transport and provides a tool for analysis of changes in mercury load related to daily precipitation, evaporation, and runoff from storms. The model also allows for simulation of colloidal transport of total mercury in surface water. Previous models for the watershed only simulated average yearly conditions and dissolved concentrations that are not sufficient for predicting mercury flux under variable flow conditions that control colloidal transport of mercury in the watershed. The transport of mercury from groundwater to surface water from mercury sources identified from information in the Oak Ridge Environmental Information System was simulated using a watershed scale model calibrated to match observed daily creek flow, total suspended solids and mercury fluxes. Mercury sources at the former Building 81-10 area, where mercury was previously retorted, were modeled using a telescopic refined mesh with boundary conditions extracted from the watershed model. Modeling on a watershed scale indicated that only source excavation for soils/sediment in the vicinity of UEFPC had any effect on mercury flux in surface water. The simulations showed that colloidal transport contributed 85 percent of the total mercury flux leaving the UEFPC watershed under high flow conditions. Simulation of dissolved mercury transport from liquid elemental mercury and adsorbed sources in soil at former Building 81-10 indicated that dissolved concentrations are orders of magnitude

  16. Three-dimensional modeling of nitrate-N transport in vadose zone: Roles of soil heterogeneity and groundwater flux

    Science.gov (United States)

    Akbariyeh, Simin; Bartelt-Hunt, Shannon; Snow, Daniel; Li, Xu; Tang, Zhenghong; Li, Yusong

    2018-04-01

    Contamination of groundwater from nitrogen fertilizers in agricultural lands is an important environmental and water quality management issue. It is well recognized that in agriculturally intensive areas, fertilizers and pesticides may leach through the vadose zone and eventually reach groundwater. While numerical models are commonly used to simulate fate and transport of agricultural contaminants, few models have considered a controlled field work to investigate the influence of soil heterogeneity and groundwater flow on nitrate-N distribution in both root zone and deep vadose zone. In this work, a numerical model was developed to simulate nitrate-N transport and transformation beneath a center pivot-irrigated corn field on Nebraska Management System Evaluation area over a three-year period. The model was based on a realistic three-dimensional sediment lithology, as well as carefully controlled irrigation and fertilizer application plans. In parallel, a homogeneous soil domain, containing the major sediment type of the site (i.e. sandy loam), was developed to conduct the same water flow and nitrate-N leaching simulations. Simulated nitrate-N concentrations were compared with the monitored nitrate-N concentrations in 10 multi-level sampling wells over a three-year period. Although soil heterogeneity was mainly observed from top soil to 3 m below the surface, heterogeneity controlled the spatial distribution of nitrate-N concentration. Soil heterogeneity, however, has minimal impact on the total mass of nitrate-N in the domain. In the deeper saturated zone, short-term variations of nitrate-N concentration correlated with the groundwater level fluctuations.

  17. HYDRASTAR - a code for stochastic simulation of groundwater flow

    International Nuclear Information System (INIS)

    Norman, S.

    1992-05-01

    The computer code HYDRASTAR was developed as a tool for groundwater flow and transport simulations in the SKB 91 safety analysis project. Its conceptual ideas can be traced back to a report by Shlomo Neuman in 1988, see the reference section. The main idea of the code is the treatment of the rock as a stochastic continuum which separates it from the deterministic methods previously employed by SKB and also from the discrete fracture models. The current report is a comprehensive description of HYDRASTAR including such topics as regularization or upscaling of a hydraulic conductivity field, unconditional and conditional simulation of stochastic processes, numerical solvers for the hydrology and streamline equations and finally some proposals for future developments

  18. PCR detection of groundwater bacteria associated with colloidal transport

    Energy Technology Data Exchange (ETDEWEB)

    Cruz-Perez, P.; Stetzenbach, L.D.; Alvarez, A.J.

    1996-02-29

    Colloidal transport may increase the amount of contaminant material than that which could be transported by water flow alone. The role of colloids in groundwater contaminant transport is complicated and may involve many different processes, including sorption of elements onto colloidal particles, coagulation/dissolution, adsorption onto solid surfaces, filtration, and migration. Bacteria are known to concentrate minerals and influence the transport of compounds in aqueous environments and may also serve as organic colloids, thereby influencing subsurface transport of radionuclides and other contaminants. The initial phase of the project consisted of assembling a list of bacteria capable of sequestering or facilitating mineral transport. The development and optimization of the PCR amplification assay for the detection of the organisms of interest, and the examination of regional groundwaters for those organisms, are presented for subsequent research.

  19. PCR detection of groundwater bacteria associated with colloidal transport

    International Nuclear Information System (INIS)

    Cruz-Perez, P.; Stetzenbach, L.D.; Alvarez, A.J.

    1996-01-01

    Colloidal transport may increase the amount of contaminant material than that which could be transported by water flow alone. The role of colloids in groundwater contaminant transport is complicated and may involve many different processes, including sorption of elements onto colloidal particles, coagulation/dissolution, adsorption onto solid surfaces, filtration, and migration. Bacteria are known to concentrate minerals and influence the transport of compounds in aqueous environments and may also serve as organic colloids, thereby influencing subsurface transport of radionuclides and other contaminants. The initial phase of the project consisted of assembling a list of bacteria capable of sequestering or facilitating mineral transport. The development and optimization of the PCR amplification assay for the detection of the organisms of interest, and the examination of regional groundwaters for those organisms, are presented for subsequent research

  20. Factors influencing the transport of actinides in the groundwater environment. Final report

    International Nuclear Information System (INIS)

    Sheppard, J.C.; Kittrick, J.A.

    1983-01-01

    This report summarizes investigations of factors that significantly influence the transport of actinide cations in the groundwater environment. Briefly, measurements of diffusion coefficients for Am(III), Cm(III), and Np(V) in moist US soils indicated that diffusion is negligible compared to mass transport in flowing groundwater. Diffusion coefficients do, however, indicate that, in the absence of flowing water, actinide elements will migrate only a few centimeters in a thousand years. The remaining investigations were devoted to the determination of distribution ratios (K/sub d/s) for representative US soils, factors influencing them, and chemical and physical processes related to transport of actinides in groundwaters. The computer code GARD was modified to include complex formation to test the importance of humic acid complexing on the rate of transport of actinides in groundwaters. Use of the formation constant and a range of humic acid, even at rather low concentrations of 10 -5 to 10 -6 molar, significantly increases the actinide transport rate in a flowing aquifer. These computer calculations show that any strong complexing agent will have a similar effect on actinide transport in the groundwater environment. 32 references, 9 figures

  1. Simulation of Groundwater Mounding Beneath Hypothetical Stormwater Infiltration Basins

    Science.gov (United States)

    Carleton, Glen B.

    2010-01-01

    Groundwater mounding occurs beneath stormwater management structures designed to infiltrate stormwater runoff. Concentrating recharge in a small area can cause groundwater mounding that affects the basements of nearby homes and other structures. Methods for quantitatively predicting the height and extent of groundwater mounding beneath and near stormwater Finite-difference groundwater-flow simulations of infiltration from hypothetical stormwater infiltration structures (which are typically constructed as basins or dry wells) were done for 10-acre and 1-acre developments. Aquifer and stormwater-runoff characteristics in the model were changed to determine which factors are most likely to have the greatest effect on simulating the maximum height and maximum extent of groundwater mounding. Aquifer characteristics that were changed include soil permeability, aquifer thickness, and specific yield. Stormwater-runoff variables that were changed include magnitude of design storm, percentage of impervious area, infiltration-structure depth (maximum depth of standing water), and infiltration-basin shape. Values used for all variables are representative of typical physical conditions and stormwater management designs in New Jersey but do not include all possible values. Results are considered to be a representative, but not all-inclusive, subset of likely results. Maximum heights of simulated groundwater mounds beneath stormwater infiltration structures are the most sensitive to (show the greatest change with changes to) soil permeability. The maximum height of the groundwater mound is higher when values of soil permeability, aquifer thickness, or specific yield are decreased or when basin depth is increased or the basin shape is square (and values of other variables are held constant). Changing soil permeability, aquifer thickness, specific yield, infiltration-structure depth, or infiltration-structure shape does not change the volume of water infiltrated, it changes the

  2. Stochastic simulation of regional groundwater flow in Beishan area

    International Nuclear Information System (INIS)

    Dong Yanhui; Li Guomin

    2010-01-01

    Because of the hydrogeological complexity, traditional thinking of aquifer characteristics is not appropriate for groundwater system in Beishan area. Uncertainty analysis of groundwater models is needed to examine the hydrologic effects of spatial heterogeneity. In this study, fast Fourier transform spectral method (FFTS) was used to generate the random horizontal permeability parameters. Depth decay and vertical anisotropy of hydraulic conductivity were included to build random permeability models. Based on high-performance computers, hundreds of groundwater flow models were simulated. Through stochastic simulations, the effect of heterogeneity to groundwater flow pattern was analyzed. (authors)

  3. Numerical simulation and impact assessment of a groundwater pollution based on MODFLOW

    International Nuclear Information System (INIS)

    Liu Dongxu; Si Gaohua; Zheng Junfang; Yu Jing; Liu Yong; Chen Jianjie; Ma Jinzhu

    2013-01-01

    Based on MODFLOW, SRTM3 DEM data and GIS tool, a saturated-zone groundwater flow and radionuclide transport numerical model in a research area had been developed to evaluate the migration trend and environmental impact. The results showed that 3 H transporting with the groundwater had a fast velocity and a pulse concentration which can not reduce to acceptable level within short times. that may cause groundwater pollution in downstream region. However, 90 Sr was transported slowly with the groundwater, and may only cause a pollution area of about 200 m around the source. (authors)

  4. Software packages for simulating groundwater flow and the spreading of soluble and insoluble admixtures in aquifers

    International Nuclear Information System (INIS)

    Roshal, A.A.; Klein, I.S.; Svishchov, A.M.

    1993-01-01

    Software programs are described designed for solving hydrogeological and environmental problems related to the analysis and prediction of groundwater flow and the spreading of solutes and insolubles in the saturated zones. The software package GWFS (Ground Water Flow Simulation) allows for simulating steady-state and unsteady-state flow in confined, unconfined, and confined-unconfined multi-layer and quasi-3D isotropic and anisotropic aquifer systems. Considered are intra-layer sources and sinks, infiltration, inter-layer leakages, the interrelationships with surface reservoirs and streams, interrelationships with the drains, aquifer discharge to surface sources. The MTS (Mass Transport Simulation) package is designed for solving solute transport problems. Taken into account is convective transport, hydrodynamic dispersion and diffusion, linear equilibrium sorption. The method of characteristics is being implemented here using the ''particles-in-cells'' scheme in which the transport is modeled with the help of tracers. The software package OWFS (Oil-Water Flow Simulation) is designed for the simulation of hydrocarbon (oil-water) migration in aquifers

  5. Groundwater flow modelling at the Olkiluoto site, Finland

    International Nuclear Information System (INIS)

    Loefman, J.

    1996-01-01

    Preliminary site investigations for spent fuel disposal has been carried out at the Olkiluoto site, Finland. During the investigations high salt concentrations were measured in the groundwater samples deep in the bedrock. In this study, the groundwater flow is analyzed at Olkiluoto taking into account the effects of salinity. The transient simulations are performed by solving coupled and non-linear partial differential equations describing the flow and solute transport. A site-specific simulation model for flow and transport is developed on the basis of the field investigations. The simulations are carried out for a period that started when the highest hills at Olkiluoto rose above sea level. The simulation period continues until the present day. The results of the coupled simulations were strongly dependent on the poorly known initial salinity distribution in the solution domain. The DP approximation together with the EC approximation proved to be a useful complementary approach when simulating solute transport in a fractured rock mass. The simulations also confirm the assumption that the realistic simulation of groundwater flow at Olkiluoto requires taking into account the effects of salinity

  6. Mass transport by groundwater

    International Nuclear Information System (INIS)

    Ledoux, E.; Goblet, P.; Jamet, Ph.; De Marsily, G.; Des Orres, P.E.; Lewi, J.

    1991-01-01

    The first analyses of the safety of radioactive waste disposal published in 1970s were mostly of a generic type using the models of radionuclide migration in the geosphere. These simply constructed models gave way to more sophisticated techniques in order to represent better the complexity and diversity of geological media. In this article, it is attempted to review the various concepts used to quantify radionuclide migration and the evolution of their incorporation into the models. First, it was examined how the type of discontinuity occurring in geological media affects the choice of a representative model. The principle of transport in the subsurface was reviewed, and the effect that coupled processes exert to groundwater flow and mass migration was discussed. The processes that act directly to cause groundwater flow were distinguished. The method of validating such models by comparing the results with the geochemical systems in nature was explained. (K.I.)

  7. GRRR. The EXPECT groundwater model for transport of solutes

    NARCIS (Netherlands)

    Meijers R; Sauter FJ; Veling EJM; van Grinsven JJM; Leijnse A; Uffink GJM; MTV; CWM; LBG

    1994-01-01

    In this report the design and first test results are presented of the EXPECT groundwater module for transport of solutes GRRR (GRoundwater source Receptor Relationships). This model is one of the abiotic compartment modules of the EXPECT model. The EXPECT model is a tool for scenario development

  8. Simulation of the groundwater flow of the Kivetty area

    International Nuclear Information System (INIS)

    Taivassalo, V.; Meszaros, F.

    1994-02-01

    Teollisuuden Voima Oy (TVO) is preparing for the final disposal of spent nuclear fuel into crystalline bedrock in Finland. Groundwater flow modelling is a part of the preliminary site investigation work. The aim is to simulate groundwater flow as realistically as possible in view of the experimental data available. Three dimensional groundwater flow modelling is based on a conceptual bedrock model. The modelling results will be used in the site evaluation process. Observations from flow simulations will also be used to identify and study uncertainties included in the site characterization. First a conceptual flow model for the Kivetty site in Konginkangas was developed. As a second stage the flow model was calibrated. The goal was to increase the reality of the model. To evaluate the reality of the flow model, the values of the input and output parameters were compared with the field data. Finally groundwater flow simulation results were computed and groundwater flow at the Kivetty area was analysed. (50 refs., 78 figs., 7 tabs.)

  9. Groundwater and solute transport modeling at Hyporheic zone of upper part Citarum River

    Science.gov (United States)

    Iskandar, Irwan; Farazi, Hendy; Fadhilah, Rahmat; Purnandi, Cipto; Notosiswoyo, Sudarto

    2017-06-01

    Groundwater and surface water interaction is an interesting topic to be studied related to the water resources and environmental studies. The study of interaction between groundwater and river water at the Upper Part Citarum River aims to know the contribution of groundwater to the river or reversely and also solute transport of dissolved ions between them. Analysis of drill logs, vertical electrical sounding at the selected sections, measurement of dissolved ions, and groundwater modeling were applied to determine the flow and solute transport phenomena at the hyporheic zone. It showed the hyporheic zone dominated by silt and clay with hydraulic conductivity range from 10-4∼10-8 m/s. The groundwater flowing into the river with very low gradient and it shows that the Citarum River is a gaining stream. The groundwater modeling shows direct seepage of groundwater into the Citarum River is only 186 l/s, very small compared to the total discharge of the river. Total dissolved ions of the groundwater ranged from 200 to 480 ppm while the river water range from 200 to 2,000 ppm. Based on solute transport modeling it indicates dissolved ions dispersion of the Citarum River into groundwater may occur in some areas such as Bojongsoang-Dayeuh Kolot and Nanjung. This situation would increase the dissolved ions in groundwater in the region due to the contribution of the Citarum River. The results of the research can be a reference for further studies related to the mechanism of transport of the pollutants in the groundwater around the Citarum River.

  10. Review: Selenium contamination, fate, and reactive transport in groundwater in relation to human health

    Science.gov (United States)

    Bailey, Ryan T.

    2017-06-01

    Selenium (Se) is an essential micro-nutrient for humans, but can be toxic at high levels of intake. Se deficiency and Se toxicity are linked with serious diseases, with some regions worldwide experiencing Se deficiency due to Se-poor rocks and soils and other areas dealing with Se toxicity due to the presence of Se-enriched geologic materials. In addition, Se is consumed primarily through plants that take up Se from soil and through animal products that consume these plants. Hence, the soil and groundwater system play important roles in determining the effect of Se on human health. This paper reviews current understanding of Se fate and transport in soil and groundwater systems and its relation to human health, with a focus on alluvial systems, soil systems, and the interface between alluvial systems and Cretaceous shale that release Se via oxidation processes. The review focuses first on the relation between Se and human health, followed by a summary of Se distribution in soil-aquifer systems, with an emphasis on the quantitative relationship between Se content in soil and Se concentration in underlying groundwater. The physical, chemical, and microbial processes that govern Se fate and transport in subsurface systems then are presented, followed by numerical modeling techniques used to simulate these processes in study regions and available remediation strategies for either Se-deficient or Se-toxic regions. This paper can serve as a guide to any field, laboratory or modeling study aimed at assessing Se fate and transport in groundwater systems and its relation to human health.

  11. Regional groundwater flow and tritium transport modeling and risk assessment of the underground test area, Nevada Test Site, Nevada

    Energy Technology Data Exchange (ETDEWEB)

    None

    1997-10-01

    underground testing areas on a regional scale. The groundwater flow model was used in conjunction with a particle-tracking code to define the pathlines followed by groundwater particles originating from 415 points associated with 253 nuclear test locations. Three of the most rapid pathlines were selected for transport simulations. These pathlines are associated with three nuclear test locations, each representing one of the three largest testing areas. These testing locations are: BOURBON on Yucca Flat, HOUSTON on Central Pahute Mesa, and TYBO on Western Pahute Mesa. One-dimensional stochastic tritium transport simulations were performed for the three pathlines using the Monte Carlo method with Latin hypercube sampling. For the BOURBON and TYBO pathlines, sources of tritium from other tests located along the same pathline were included in the simulations. Sensitivity analyses were also performed on the transport model to evaluate the uncertainties associated with the geologic model, the rates of groundwater flow, the tritium source, and the transport parameters. Tritium concentration predictions were found to be mostly sensitive to the regional geology in controlling the horizontal and vertical position of transport pathways. The simulated concentrations are also sensitive to matrix diffusion, an important mechanism governing the migration of tritium in fractured carbonate and volcanic rocks. Source term concentration uncertainty is most important near the test locations and decreases in importance as the travel distance increases. The uncertainty on groundwater flow rates is as important as that on matrix diffusion at downgradient locations. The risk assessment was performed to provide conservative and bounding estimates of the potential risks to human health and the environment from tritium in groundwater. Risk models were designed by coupling scenario-specific tritium intake with tritium dose models and cancer and genetic risk estimates using the Monte Carlo method

  12. [Simulation on contamination forecast and control of groundwater in a certain hazardous waste landfill].

    Science.gov (United States)

    Ma, Zhi-Fei; An, Da; Jiang, Yong-Hai; Xi, Bei-Dou; Li, Ding-Long; Zhang, Jin-Bao; Yang, Yu

    2012-01-01

    On the basis of site investigation and data collection of a certain hazardous waste landfill, the groundwater flow and solute transport coupled models were established by applying Visual Modflow software, which was used to conduct a numerical simulation that forecast the transport process of Cr6+ in groundwater and the effects of three control measures (ground-harden, leakage-proof barriers and drainage ditches) of contaminants transport after leachate leakage happened in impermeable layer of the landfill. The results show that the contamination plume of Cr6+ transports with groundwater flow direction, the contamination rang would reach the pool's boundary in 10 years, and the distance of contamination transport is 1 450 m. But the diffusion range of contamination plume would not be obviously expanded between 10 and 20 years. While the ground is hardened, the contamination plume would not reach the pool's boundary in 20 years. When the leakage-proof barrier is set in the bottom of water table aquifer, the concentration of Cr6+ is higher than that the leakage-proof barrier is unset, but the result is just opposite when setting the leakage-proof barrier in the bottom of underlying aquifer. The range of contamination plume is effectively controlled by setting drainage ditches that water discharge is 2 642 m3 x d(-1), which makes the monitoring wells would not be contaminated in 20 years. Moreover, combining the ground-harden with drainage ditches can get the best effect in controlling contaminants diffusion, and meanwhile, the drainage ditches' daily discharge is reduced to 1 878 m3 x d(-1). Therefore, it is suggested that the control measure combining the ground-harden with drainage ditches should apply to prevent contamination diffusion in groundwater when leachate leakage have happened in impermeable layer of the landfill.

  13. Simulation of the regional groundwater-flow system of the Menominee Indian Reservation, Wisconsin

    Science.gov (United States)

    Juckem, Paul F.; Dunning, Charles P.

    2015-01-01

    A regional, two-dimensional, steady-state groundwater-flow model was developed to simulate the groundwater-flow system and groundwater/surface-water interactions within the Menominee Indian Reservation. The model was developed by the U.S. Geological Survey (USGS), in cooperation with the Menominee Indian Tribe of Wisconsin, to contribute to the fundamental understanding of the region’s hydrogeology. The objectives of the regional model were to improve understanding of the groundwater-flow system, including groundwater/surface-water interactions, and to develop a tool suitable for evaluating the effects of potential regional water-management programs. The computer code GFLOW was used because of the ease with which the model can simulate groundwater/surface-water interactions, provide a framework for simulating regional groundwater-flow systems, and be refined in a stepwise fashion to incorporate new data and simulate groundwater-flow patterns at multiple scales. Simulations made with the regional model reproduce groundwater levels and stream base flows representative of recent conditions (1970–2013) and illustrate groundwater-flow patterns with maps of (1) the simulated water table and groundwater-flow directions, (2) probabilistic areas contributing recharge to high-capacity pumped wells, and (3) estimation of the extent of infiltrated wastewater from treatment lagoons.

  14. The development of high performance numerical simulation code for transient groundwater flow and reactive solute transport problems based on local discontinuous Galerkin method

    International Nuclear Information System (INIS)

    Suzuki, Shunichi; Motoshima, Takayuki; Naemura, Yumi; Kubo, Shin; Kanie, Shunji

    2009-01-01

    The authors develop a numerical code based on Local Discontinuous Galerkin Method for transient groundwater flow and reactive solute transport problems in order to make it possible to do three dimensional performance assessment on radioactive waste repositories at the earliest stage possible. Local discontinuous Galerkin Method is one of mixed finite element methods which are more accurate ones than standard finite element methods. In this paper, the developed numerical code is applied to several problems which are provided analytical solutions in order to examine its accuracy and flexibility. The results of the simulations show the new code gives highly accurate numeric solutions. (author)

  15. The role of groundwater transport in aquatic mercury cycling

    Science.gov (United States)

    Krabbenhoft, David P.; Babiarz, Christopher L.

    1992-01-01

    Mercury, which is transported globally by atmospheric pathways to remote aquatic environments, is a ubiquitous contaminant at very low (nanograms Hg per liter) aqueous concentrations. Until recently, however, analytical and sampling techniques were not available for freshwater systems to quantify the actual levels of mercury concentrations without introducing significant contamination artifacts. Four different sampling strategies were used to evaluate ground water flow as a mercury source and transport mechanism within aquatic systems. The sampling strategies employ ultraclean techniques to determine mercury concentrations in groundwater and pore water near Pallette Lake, Wisconsin. Ambient groundwater concentrations are about 2–4 ng Hg L−1, whereas pore waters near the sediment/water interface average about 12 ng Hg L−1, emphasizing the importance of biogeochemical processes near the interface. Overall, the groundwater system removes about twice as much mercury (1.5 g yr−1) as it contributes (0.7 g yr−1) to Pallette Lake. About three fourths of the groundwater mercury load is recycled, thought to be derived from the water column.

  16. Ground-water solute transport modeling using a three-dimensional scaled model

    International Nuclear Information System (INIS)

    Crider, S.S.

    1987-01-01

    Scaled models are used extensively in current hydraulic research on sediment transport and solute dispersion in free surface flows (rivers, estuaries), but are neglected in current ground-water model research. Thus, an investigation was conducted to test the efficacy of a three-dimensional scaled model of solute transport in ground water. No previous results from such a model have been reported. Experiments performed on uniform scaled models indicated that some historical problems (e.g., construction and scaling difficulties; disproportionate capillary rise in model) were partly overcome by using simple model materials (sand, cement and water), by restricting model application to selective classes of problems, and by physically controlling the effect of the model capillary zone. Results from these tests were compared with mathematical models. Model scaling laws were derived for ground-water solute transport and used to build a three-dimensional scaled model of a ground-water tritium plume in a prototype aquifer on the Savannah River Plant near Aiken, South Carolina. Model results compared favorably with field data and with a numerical model. Scaled models are recommended as a useful additional tool for prediction of ground-water solute transport

  17. Comparison of tritium concentrations in rainwater, simulated infiltrating water, and groundwater

    International Nuclear Information System (INIS)

    Ishii, Yoshiyuki; Saito, Masaaki; Imaizumi, Hiroshi; Kato, Norio; Kitaoka, Koichi

    2014-01-01

    The tritium concentration in initial groundwater(i.e., freshly infiltrating rainwater) is necessary for groundwater dating. We collected simulated infiltrating water as the initial groundwater and examined its characteristics for tritium concentration. First, in Tokyo, the tritium concentration of simulated infiltrating water was compared with that of rainwater, atmospheric moisture, groundwater, spring water, and sap water. While rainwater, atmospheric moisture, and simulated infiltrating water remarkably changed month-to-month or with every rainfall event, groundwater and spring water were nearly constant throughout the year. Second, we collected the simulated infiltrating water monthly at four sampling sites widely dispersed across Japan(i.e., Sapporo, Niigata, Tokyo, and Matsuyama) from 2004 to 2010. Sapporo and Niigata showed high tritium concentrations as compared with the relatively low concentrations in Tokyo and Matsuyama. These results indicate that we can obtain annual maximum and minimum concentrations at each site, and that we can estimate the tritium concentration in initial groundwater at each site by using a mixing model composed of these maximum and minimum concentrations. (author)

  18. Groundwater Impacts of Radioactive Wastes and Associated Environmental Modeling Assessment

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Rui; Zheng, Chunmiao; Liu, Chongxuan

    2012-11-01

    This article provides a review of the major sources of radioactive wastes and their impacts on groundwater contamination. The review discusses the major biogeochemical processes that control the transport and fate of radionuclide contaminants in groundwater, and describe the evolution of mathematical models designed to simulate and assess the transport and transformation of radionuclides in groundwater.

  19. Hydrogeochemistry and simulated solute transport, Piceance Basin, northwestern Colorado

    Science.gov (United States)

    Robson, S.G.; Saulnier, G.J.

    1981-01-01

    Oil-shale mining activities in Piceance basin in northwestern Colorado could adversely affect the ground- and surface-water quality in the basin. This study of the hydrology and geochemistry of the area used ground-water solute-transport-modeling techniques to investigate the possible impact of the mines on water quality. Maps of the extent and structure of the aquifer were prepared and show that a saturated thickness of 2,000 feet occurs in the northeast part of the basin. Ground-water recharge in the upland areas in the east, south, and west parts of the basin moves down into deeper zones in the aquifer and laterally to the discharge areas along Piceance and Yellow Creeks. The saline zone and the unsaturated zone provide the majority of the dissolved solids found in the ground water. Precipitation, ion-exchange, and oxidation-reduction reactions are also occuring in the aquifer. Model simulations of ground-water pumpage in tracts C-a and C-b indicate that the altered direction of ground-water movement near the pumped mines will cause an improvement in ground-water quality near the mines and a degradation of water quality downgradient from the tracts. Model simulations of mine leaching in tract C-a and C-b indicate that equal rates of mine leaching in the tracts will produce much different effects on the water quality in the basin. Tract C-a, by virtue of its remote location from perennial streams, will primarily degrade the ground-water quality over a large area to the northeast of the tract. Tract C-b, by contrast, will primarily degrade the surface-water quality in Piceance Creek, with only localized effects on the ground-water quality. (USGS)

  20. Modeling the effects of atmospheric emissions on groundwater composition

    International Nuclear Information System (INIS)

    Brown, T.J.

    1994-01-01

    A composite model of atmospheric, unsaturated and groundwater transport is developed to evaluate the processes determining the distribution of atmospherically derived contaminants in groundwater systems and to test the sensitivity of simulated contaminant concentrations to input parameters and model linkages. One application is to screen specific atmospheric emissions for their potential in determining groundwater age. Temporal changes in atmospheric emissions could provide a recognizable pattern in the groundwater system. The model also provides a way for quantifying the significance of uncertainties in the tracer source term and transport parameters on the contaminant distribution in the groundwater system, an essential step in using the distribution of contaminants from local, point source atmospheric emissions to examine conceptual models of groundwater flow and transport

  1. Numerical models of groundwater flow and transport

    International Nuclear Information System (INIS)

    Konikow, L.F.

    1996-01-01

    This chapter reviews the state-of-the-art in deterministic modeling of groundwater flow and transport processes, which can be used for interpretation of isotope data through groundwater flow analyses. Numerical models which are available for this purpose are described and their applications to complex field problems are discussed. The theoretical bases of deterministic modeling are summarized, and advantages and limitations of numerical models are described. The selection of models for specific applications and their calibration procedures are described, and results of a few illustrative case study type applications are provided. (author). 145 refs, 17 figs, 2 tabs

  2. Numerical models of groundwater flow and transport

    Energy Technology Data Exchange (ETDEWEB)

    Konikow, L F [Geological Survey, Reston, VA (United States)

    1996-10-01

    This chapter reviews the state-of-the-art in deterministic modeling of groundwater flow and transport processes, which can be used for interpretation of isotope data through groundwater flow analyses. Numerical models which are available for this purpose are described and their applications to complex field problems are discussed. The theoretical bases of deterministic modeling are summarized, and advantages and limitations of numerical models are described. The selection of models for specific applications and their calibration procedures are described, and results of a few illustrative case study type applications are provided. (author). 145 refs, 17 figs, 2 tabs.

  3. TRING: a computer program for calculating radionuclide transport in groundwater

    International Nuclear Information System (INIS)

    Maul, P.R.

    1984-12-01

    The computer program TRING is described which enables the transport of radionuclides in groundwater to be calculated for use in long term radiological assessments using methods described previously. Examples of the areas of application of the program are activity transport in groundwater associated with accidental spillage or leakage of activity, the shutdown of reactors subject to delayed decommissioning, shallow land burial of intermediate level waste and geologic disposal of high level waste. Some examples of the use of the program are given, together with full details to enable users to run the program. (author)

  4. Why is the Groundwater Level Rising? A Case Study Using HARTT to Simulate Groundwater Level Dynamic.

    Science.gov (United States)

    Yihdego, Yohannes; Danis, Cara; Paffard, Andrew

    2017-12-01

    Groundwater from a shallow unconfined aquifer at a site in coastal New South Wales has been causing recent water logging issues. A trend of rising groundwater level has been anecdotally observed over the last 10 years. It was not clear whether the changes in groundwater levels were solely natural variations within the groundwater system or whether human interference was driving the level up. Time series topographic images revealed significant surrounding land use changes and human modification to the environment of the groundwater catchment. A statistical model utilising HARTT (multiple linear regression hydrograph analysis method) simulated the groundwater level dynamics at five key monitoring locations and successfully showed a trend of rising groundwater level. Utilising hydrogeological input from field investigations, the model successfully simulated the rise in the water table over time to the present day levels, whilst taking into consideration rainfall and land changes. The underlying geological/land conditions were found to be just as significant as the impact of climate variation. The correlation coefficient for the monitoring bores (MB), excluding MB4, show that the groundwater level fluctuation can be explained by the climate variable (rainfall) with the lag time between the atypical rainfall and groundwater level ranging from 4 to 7 months. The low R2 value for MB4 indicates that there are factors missing in the model which are primarily related to human interference. The elevated groundwater levels in the affected area are the result of long term cumulative land use changes, instigated by humans, which have directly resulted in detrimental changes to the groundwater aquifer properties.

  5. Stochastic simulation of ecohydrological interactions between vegetation and groundwater

    Science.gov (United States)

    Dwelle, M. C.; Ivanov, V. Y.; Sargsyan, K.

    2017-12-01

    The complex interactions between groundwater and vegetation in the Amazon rainforest may yield vital ecophysiological interactions in specific landscape niches such as buffering plant water stress during dry season or suppression of water uptake due to anoxic conditions. Representation of such processes is greatly impacted by both external and internal sources of uncertainty: inaccurate data and subjective choice of model representation. The models that can simulate these processes are complex and computationally expensive, and therefore make it difficult to address uncertainty using traditional methods. We use the ecohydrologic model tRIBS+VEGGIE and a novel uncertainty quantification framework applied to the ZF2 watershed near Manaus, Brazil. We showcase the capability of this framework for stochastic simulation of vegetation-hydrology dynamics. This framework is useful for simulation with internal and external stochasticity, but this work will focus on internal variability of groundwater depth distribution and model parameterizations. We demonstrate the capability of this framework to make inferences on uncertain states of groundwater depth from limited in situ data, and how the realizations of these inferences affect the ecohydrological interactions between groundwater dynamics and vegetation function. We place an emphasis on the probabilistic representation of quantities of interest and how this impacts the understanding and interpretation of the dynamics at the groundwater-vegetation interface.

  6. Using StorAge Selection Functions to Improve Simulation of Groundwater Nitrate Lag Times in the SWAT Modeling Framework.

    Science.gov (United States)

    Wilusz, D. C.; Fuka, D.; Cho, C.; Ball, W. P.; Easton, Z. M.; Harman, C. J.

    2017-12-01

    Intensive agriculture and atmospheric deposition have dramatically increased the input of reactive nitrogen into many watersheds worldwide. Reactive nitrogen can leach as nitrate into groundwater, which is stored and eventually released over years to decades into surface waters, potentially degrading water quality. To simulate the fate and transport of groundwater nitrate, many researchers and practitioners use the Soil and Water Assessment Tool (SWAT) or an enhanced version of SWAT that accounts for topographically-driven variable source areas (TopoSWAT). Both SWAT and TopoSWAT effectively assume that nitrate in the groundwater reservoir is well-mixed, which is known to be a poor assumption at many sites. In this study, we describe modifications to TopoSWAT that (1) relax the assumption of groundwater well-mixedness, (2) more flexibly parameterize groundwater transport as a time-varying distribution of travel times using the recently developed theory of rank StorAge Selection (rSAS) functions, and (3) allow for groundwater age to be represented by position on the hillslope or hydrological distance from the stream. The approach conceptualizes the groundwater aquifer as a population of water parcels entering as recharge with a particular nitrate concentration, aging as they move through storage, and eventually exiting as baseflow. The rSAS function selects the distribution of parcel ages that exit as baseflow based on a parameterized probability distribution; this distribution can be adjusted to preferentially select different distributions of young and old parcels in storage so as to reproduce (in principle) any form of transport. The modified TopoSWAT model (TopoSWAT+rSAS) is tested at a small agricultural catchment in the Eastern Shore, MD with an extensive hydrologic and hydrochemical data record for calibration and evaluation. The results examine (1) the sensitivity of TopoSWAT+rSAS modeling of nitrate transport to assumptions about the distribution of travel

  7. Global simulation of interactions between groundwater and terrestrial ecosystems

    Science.gov (United States)

    Braakhekke, M. C.; Rebel, K.; Dekker, S. C.; Smith, B.; Van Beek, L. P.; Sutanudjaja, E.; van Kampenhout, L.; Wassen, M. J.

    2016-12-01

    In many places in the world ecosystems are influenced by the presence of a shallow groundwater table. In these regions upward water flux due to capillary rise increases soil moisture availability in the root zone, which has strong positive effect on evapotranspiration. Additionally it has important consequences for vegetation dynamics and fluxes of carbon and nitrogen. Under water limited conditions shallow groundwater stimulates vegetation productivity, and soil organic matter decomposition while under saturated conditions groundwater may have a negative effect on these processes due to lack of oxygen. Furthermore, since plant species differ with respect to their root distribution, preference for moisture conditions, and resistance to oxygen stress, shallow groundwater also influences vegetation type. Finally, processes such as denitrification and methane production occur under strictly anaerobic conditions and are thus strongly influenced by moisture availability. Most global hydrological models and several land surface models simulate groundwater table dynamics and their effects on land surface processes. However, these models typically have relatively simplistic representation of vegetation and do not consider changes in vegetation type and structure and are therefore less suitable to represent effects of groundwater on biogeochemical fluxes. Dynamic global vegetation models (DGVMs), describe land surface from an ecological perspective, combining detailed description of vegetation dynamics and structure and biogeochemical processes. These models are thus more appropriate to simulate the ecological and biogeochemical effects of groundwater interactions. However, currently virtually all DGVMs ignore these effects, assuming that water tables are too deep to affect soil moisture in the root zone. We have implemented a tight coupling between the dynamic global ecosystem model LPJ-GUESS and the global hydrological model PCR-GLOBWB. Using this coupled model we aim to

  8. Effects of Groundwater Dynamics on Hydrometeorological Conditions over South America: Analysis of Offline NoahMP and Fully-coupled WRF-NoahMP Simulations

    Science.gov (United States)

    Martinez-Agudelo, J. A.; Dominguez, F.; Miguez-Macho, G.

    2014-12-01

    Renalysis data suggests that nearly 20% of the atmospheric moisture over the La Plata basin comes from Amazonian Evapotranspiration (ET). However, these estimates of ET are model dependent. Simulations using land-surface models (LSMs) in off-line mode (i.e. with prescribed atmospheric forcing) have shown that Amazonian ET depends on the groundwater dynamics. In this study we use the NoahMP LSM in off-line mode and the coupled system WRF-NoahMP to assess the role of groundwater on South American ET. In particular, we study the role of the groundwater in sustaining ET during the dry season in the southern Amazon and the La Plata basin. We compare simulations that do not account for the groundwater reservoir (free drainage approach) with simulations that include the Miguez-Macho and Fan parameterization to represent the groundwater storage, its lateral flow, and its interaction with the unsaturated zone. The off-line simulations show the effects associated solely with groundwater dynamics (as opposed to coupled land-atmosphere processes), while the coupled simulations provide information about the regulation and/or response from the atmosphere. Preliminary results from the coupled system suggest that the largest effects of the groundwater on ET are observed during the austral dry season. ET is larger over regions of Bolivia, Paraguay and Argentina when groundwater is included, due to the existence of a relatively shallow water table over these regions, which via upward capillary fluxes reduces drainage during the rainy season and increases soil moisture availability in the dry season. These differences in the simulated ET could have an impact on the estimates of the transport of atmospheric moisture to La Plata basin.

  9. Modeling Groundwater-Surface Water Interaction and Contaminant Transport of Chlorinated Solvent Contaminated Site

    Science.gov (United States)

    Yimer Ebrahim, Girma; Jonoski, Andreja; van Griensven, Ann; Dujardin, Juliette; Baetelaan, Okke; Bronders, Jan

    2010-05-01

    Chlorinated-solvent form one of the largest groups of environmental chemicals. Their use and misuse in industry have lead to a large entry of these chemicals into the environment, resulting in widespread dissemination and oftentimes environmental contamination. Chlorinated solvent contamination of groundwater resources has been widely reported. For instance, there has been much interest in the assessment of these contaminant levels and their evolutions with time in the groundwater body below the Vilvoorde-Machelen industrial area (Belgium). The long industrial history of the area has lead to complex patterns of pollution from multiple sources and the site has been polluted to the extent that individual plumes are not definable any more. Understanding of groundwater/surface water interaction is a critical component for determining the fate of contaminant both in streams and ground water due to the fact that groundwater and surface water are in continuous dynamic interaction in the hydrologic cycle. The interaction has practical consequences in the quantity and quality of water in either system in the sense that depletion and/or contamination of one of the system will eventually affect the other one. The transition zone between a stream and its adjacent aquifer referred to as the hyporheic zone plays a critical role in governing contaminant exchange and transformation during water exchange between the two water bodies. The hyporheic zone of Zenne River ( the main receptor ) is further complicated due to the fact that the river banks are artificially trained with sheet piles along its reach extending some 12 m below the surface. This study demonstrates the use of MODFLOW, a widely used modular three-dimensional block-centred finite difference, saturated flow model for simulating the flow and direction of movement of groundwater through aquifer and stream-aquifer interaction and the use of transport model RT3D, a three-dimensional multi-species reactive transport model

  10. Groundwater flow and transport modelling during a glaciation period

    International Nuclear Information System (INIS)

    Jaquet, O.; Siegel, P.

    2003-01-01

    Subsequent to earlier work, SKB has decided to carry out additional hydrogeological modelling studies related to glaciation effects at Aespoe. In particular, sub glacial groundwater flow and the impact assessment on a repository require further studies. As compared to the previous model, the domain geometry and processes involved remain identical, but this time, numerical calculations are performed with the NAMMU package (version 7.1.1) using a finite element formulation. Modified assumptions corresponding to specific boundary conditions are implemented and additional variations of the base case are simulated. The objectives of the study are based on the technical specifications established by SKB. The main objectives may be summarised as follows: Enhancement of the understanding of sub glacial groundwater flow due to basal ice melting. Evaluation of the impact of sub glacial roundwater flow on a repository with respect to its position to the ice margin of the glacier. Assessment of the feasibility of performing large 3D simulations of density-driven flow induced by variable salinity of the groundwater using the NAMMU package. The report begins with an account of the modelling approach applied. Then, the results of the different cases simulated are described, analysed and interpreted in detail. Finally, conclusions are drawn up together with some recommendations related to potential modelling issues for the future. The objectives proposed for the groundwater flow and transport modelling for period of glaciation have been met: The results have shown the importance of the ice tunnels in governing sub glacial groundwater flow due to basal ice melting. The influence of the ice tunnels on the salinity distribution is significant as is their impact on the flow trajectories and, hence, on the resulting travel times. The results of simulation S0 have revealed that no steady-state flow conditions are reached. Due to the chosen salt boundary conditions, salt will continue to

  11. Study of groundwater colloids and their ability to transport radionuclides

    International Nuclear Information System (INIS)

    Tjus, K.; Wikberg, P.

    1987-03-01

    Natural occurring colloids in groundwater can adsorb and transport released radionuclides. In this work groundwater colloids have been investigated with zeta potential measurements and dynamic light scattering. The goal was i) to estimate the detection limits of the Institute's equipment for particle size estimation with dynamic light scattering and zeta potential with dynamic light scattering combined with estimation of Doppler shift in the scattered light frequency; ii) to examine several different groundwaters (Stripa, Kamlunge, Svartboberget). The possibility to apply a theoretical adsorption model for interpreting the results is also discussed. (orig.)

  12. ArcNLET: A GIS-based software to simulate groundwater nitrate load from septic systems to surface water bodies

    Science.gov (United States)

    Rios, J. Fernando; Ye, Ming; Wang, Liying; Lee, Paul Z.; Davis, Hal; Hicks, Rick

    2013-03-01

    Onsite wastewater treatment systems (OWTS), or septic systems, can be a significant source of nitrates in groundwater and surface water. The adverse effects that nitrates have on human and environmental health have given rise to the need to estimate the actual or potential level of nitrate contamination. With the goal of reducing data collection and preparation costs, and decreasing the time required to produce an estimate compared to complex nitrate modeling tools, we developed the ArcGIS-based Nitrate Load Estimation Toolkit (ArcNLET) software. Leveraging the power of geographic information systems (GIS), ArcNLET is an easy-to-use software capable of simulating nitrate transport in groundwater and estimating long-term nitrate loads from groundwater to surface water bodies. Data requirements are reduced by using simplified models of groundwater flow and nitrate transport which consider nitrate attenuation mechanisms (subsurface dispersion and denitrification) as well as spatial variability in the hydraulic parameters and septic tank distribution. ArcNLET provides a spatial distribution of nitrate plumes from multiple septic systems and a load estimate to water bodies. ArcNLET's conceptual model is divided into three sub-models: a groundwater flow model, a nitrate transport and fate model, and a load estimation model which are implemented as an extension to ArcGIS. The groundwater flow model uses a map of topography in order to generate a steady-state approximation of the water table. In a validation study, this approximation was found to correlate well with a water table produced by a calibrated numerical model although it was found that the degree to which the water table resembles the topography can vary greatly across the modeling domain. The transport model uses a semi-analytical solution to estimate the distribution of nitrate within groundwater, which is then used to estimate a nitrate load using a mass balance argument. The estimates given by ArcNLET are

  13. A Transient Numerical Simulation of Perched Ground-Water Flow at the Test Reactor Area, Idaho National Engineering and Environmental Laboratory, Idaho, 1952-94

    International Nuclear Information System (INIS)

    Orr, B. R.

    1999-01-01

    Studies of flow through the unsaturated zone and perched ground-water zones above the Snake River Plain aquifer are part of the overall assessment of ground-water flow and determination of the fate and transport of contaminants in the subsurface at the Idaho National Engineering and Environmental Laboratory (INEEL). These studies include definition of the hydrologic controls on the formation of perched ground-water zones and description of the transport and fate of wastewater constituents as they moved through the unsaturated zone. The definition of hydrologic controls requires stratigraphic correlation of basalt flows and sedimentary interbeds within the saturated zone, analysis of hydraulic properties of unsaturated-zone rocks, numerical modeling of the formation of perched ground-water zones, and batch and column experiments to determine rock-water geochemical processes. This report describes the development of a transient numerical simulation that was used to evaluate a conceptual model of flow through perched ground-water zones beneath wastewater infiltration ponds at the Test Reactor Area (TRA)

  14. Simulation of groundwater flow and interaction of groundwater and surface water on the Lac du Flambeau Reservation, Wisconsin

    Science.gov (United States)

    Juckem, Paul F.; Fienen, Michael N.; Hunt, Randall J.

    2014-01-01

    The Lac du Flambeau Band of Lake Superior Chippewa and Indian Health Service are interested in improving the understanding of groundwater flow and groundwater/surface-water interaction on the Lac du Flambeau Reservation (Reservation) in southwest Vilas County and southeast Iron County, Wisconsin, with particular interest in an understanding of the potential for contamination of groundwater supply wells and the fate of wastewater that is infiltrated from treatment lagoons on the Reservation. This report describes the construction, calibration, and application of a regional groundwater flow model used to simulate the shallow groundwater flow system of the Reservation and water-quality results for groundwater and surface-water samples collected near a system of waste-water-treatment lagoons. Groundwater flows through a permeable glacial aquifer that ranges in thickness from 60 to more than 200 feet (ft). Seepage and drainage lakes are common in the area and influence groundwater flow patterns on the Reservation. A two-dimensional, steady-state analytic element groundwater flow model was constructed using the program GFLOW. The model was calibrated by matching target water levels and stream base flows through the use of the parameter-estimation program, PEST. Simulated results illustrate that groundwater flow within most of the Reservation is toward the Bear River and the chain of lakes that feed the Bear River. Results of analyses of groundwater and surface-water samples collected downgradient from the wastewater infiltration lagoons show elevated levels of ammonia and dissolved phosphorus. In addition, wastewater indicator chemicals detected in three downgradient wells and a small downgradient stream indicate that infiltrated wastewater is moving southwest of the lagoons toward Moss Lake. Potential effects of extended wet and dry periods (within historical ranges) were evaluated by adjusting precipitation and groundwater recharge in the model and comparing the

  15. Validation of groundwater flow model using the change of groundwater flow caused by the construction of AESPOE hard rock laboratory

    International Nuclear Information System (INIS)

    Hasegawa, Takuma; Tanaka, Yasuharu

    2004-01-01

    A numerical model based on results during pre-investigation phases was applied to the groundwater flow change caused by the construction of AEspoe HRL. The drawdowns and chloride concentration during tunnel construction were simulated to validate the numerical model. The groundwater flow was induced by inflow from the Baltic Sea to the tunnel through the hydraulic conductor domain (HCD). The time series of tunnel progress and inflow, boundaries of the Baltic Sea, transmissivity and geometry of HCD are therefore important in representing the groundwater flow. The numerical model roughly represented the groundwater flow during tunnel construction. These simulations were effective in validating the numerical model for groundwater flow and solute transport. (author)

  16. Simulation of Ground-Water Flow and Effects of Ground-Water Irrigation on Base Flow in the Elkhorn and Loup River Basins, Nebraska

    Science.gov (United States)

    Peterson, Steven M.; Stanton, Jennifer S.; Saunders, Amanda T.; Bradley, Jesse R.

    2008-01-01

    Irrigated agriculture is vital to the livelihood of communities in the Elkhorn and Loup River Basins in Nebraska, and ground water is used to irrigate most of the cropland. Concerns about the sustainability of ground-water and surface-water resources have prompted State and regional agencies to evaluate the cumulative effects of ground-water irrigation in this area. To facilitate understanding of the effects of ground-water irrigation, a numerical computer model was developed to simulate ground-water flow and assess the effects of ground-water irrigation (including ground-water withdrawals, hereinafter referred to as pumpage, and enhanced recharge) on stream base flow. The study area covers approximately 30,800 square miles, and includes the Elkhorn River Basin upstream from Norfolk, Nebraska, and the Loup River Basin upstream from Columbus, Nebraska. The water-table aquifer consists of Quaternary-age sands and gravels and Tertiary-age silts, sands, and gravels. The simulation was constructed using one layer with 2-mile by 2-mile cell size. Simulations were constructed to represent the ground-water system before 1940 and from 1940 through 2005, and to simulate hypothetical conditions from 2006 through 2045 or 2055. The first simulation represents steady-state conditions of the system before anthropogenic effects, and then simulates the effects of early surface-water development activities and recharge of water leaking from canals during 1895 to 1940. The first simulation ends at 1940 because before that time, very little pumpage for irrigation occurred, but after that time it became increasingly commonplace. The pre-1940 simulation was calibrated against measured water levels and estimated long-term base flow, and the 1940 through 2005 simulation was calibrated against measured water-level changes and estimated long-term base flow. The calibrated 1940 through 2005 simulation was used as the basis for analyzing hypothetical scenarios to evaluate the effects of

  17. Evaluation of ground-water flow and solute transport in the Lompoc area, Santa Barbara County, California

    Science.gov (United States)

    Bright, Daniel J.; Nash, David B.; Martin, Peter

    1997-01-01

    Ground-water quality in the Lompoc area, especially in the Lompoc plain, is only marginally acceptable for most uses. Demand for ground water has increased for municipal use since the late 1950's and has continued to be high for irrigation on the Lompoc plain, the principal agricultural area in the Santa Ynez River basin. As use has increased, the quality of ground water has deteriorated in some areas of the Lompoc plain. The dissolved-solids concentration in the main zone of the upper aquifer beneath most of the central and western plains has increased from less than 1,000 milligrams per liter in the 1940's to greater than 2,000 milligrams per liter in the 1960's. Dissolved- solids concentration have remained relatively constant since the 1960's. A three-dimensional finite-difference model was used to simulate ground-water flow in the Lompoc area and a two-dimensional finite-element model was used to simulate solute transport to gain a better understanding of the ground-water system and to evaluate the effects of proposed management plans for the ground-water basin. The aquifer system was simulated in the flow model as four horizontal layers. In the area of the Lompoc plain, the layers represent the shallow, middle, and main zones of the upper aquifer, and the lower aquifer. For the Lompoc upland and Lompoc terrace, the four layers represent the lower aquifer. The solute transport model was used to simulate dissolved-solids transport in the main zone of the upper aquifer beneath the Lompoc plain. The flow and solute-transport models were calibrated to transient conditions for 1941-88. A steady-state simulation was made to provide initial conditions for the transient-state simulation by using long-term average (1941-88) recharge rates. Model- simulated hydraulic heads generally were within 5 feet of measured heads in the main zone for transient conditions. Model-simulated dissolved- solids concentrations for the main zone generally differed less than 200milligrams

  18. Simultaneous simulations of uptake in plants and leaching to groundwater of cadmium and lead for arable land amended with compost or farmyard manure

    DEFF Research Database (Denmark)

    Legind, Charlotte Nielsen; Rein, Arno; Serre, Jeanne

    2012-01-01

    The water budget of soil, the uptake in plants and the leaching to groundwater of cadmium (Cd) and lead (Pb) were simulated simultaneously using a physiological plant uptake model and a tipping buckets water and solute transport model for soil. Simulations were compared to results from a ten-year...

  19. Pathogen transport in groundwater systems: contrasts with traditional solute transport

    Science.gov (United States)

    Hunt, Randall J.; Johnson, William P.

    2017-06-01

    Water quality affects many aspects of water availability, from precluding use to societal perceptions of fit-for-purpose. Pathogen source and transport processes are drivers of water quality because they have been responsible for numerous outbreaks resulting in large economic losses due to illness and, in some cases, loss of life. Outbreaks result from very small exposure (e.g., less than 20 viruses) from very strong sources (e.g., trillions of viruses shed by a single infected individual). Thus, unlike solute contaminants, an acute exposure to a very small amount of contaminated water can cause immediate adverse health effects. Similarly, pathogens are larger than solutes. Thus, interactions with surfaces and settling become important even as processes important for solutes such as diffusion become less important. These differences are articulated in "Colloid Filtration Theory", a separate branch of pore-scale transport. Consequently, understanding pathogen processes requires changes in how groundwater systems are typically characterized, where the focus is on the leading edges of plumes and preferential flow paths, even if such features move only a very small fraction of the aquifer flow. Moreover, the relatively short survival times of pathogens in the subsurface require greater attention to very fast (solute transport mechanisms discussed here, a more encompassing view of water quality and source water protection is attained. With this more holistic view and theoretical understanding, better evaluations can be made regarding drinking water vulnerability and the relation between groundwater and human health.

  20. Development of solute transport models in YMPYRÄ framework to simulate solute migration in military shooting and training areas

    Science.gov (United States)

    Warsta, L.; Karvonen, T.

    2017-12-01

    There are currently 25 shooting and training areas in Finland managed by The Finnish Defence Forces (FDF), where military activities can cause contamination of open waters and groundwater reservoirs. In the YMPYRÄ project, a computer software framework is being developed that combines existing open environmental data and proprietary information collected by FDF with computational models to investigate current and prevent future environmental problems. A data centric philosophy is followed in the development of the system, i.e. the models are updated and extended to handle available data from different areas. The results generated by the models are summarized as easily understandable flow and risk maps that can be opened in GIS programs and used in environmental assessments by experts. Substances investigated with the system include explosives and metals such as lead, and both surface and groundwater dominated areas can be simulated. The YMPYRÄ framework is composed of a three dimensional soil and groundwater flow model, several solute transport models and an uncertainty assessment system. Solute transport models in the framework include particle based, stream tube and finite volume based approaches. The models can be used to simulate solute dissolution from source area, transport in the unsaturated layers to groundwater and finally migration in groundwater to water extraction wells and springs. The models can be used to simulate advection, dispersion, equilibrium adsorption on soil particles, solubility and dissolution from solute phase and dendritic solute decay chains. Correct numerical solutions were confirmed by comparing results to analytical 1D and 2D solutions and by comparing the numerical solutions to each other. The particle based and stream tube type solute transport models were useful as they could complement the traditional finite volume based approach which in certain circumstances produced numerical dispersion due to piecewise solution of the

  1. Simulated groundwater flow paths, travel time, and advective transport of nitrogen in the Kirkwood-Cohansey aquifer system, Barnegat Bay–Little Egg Harbor Watershed, New Jersey

    Science.gov (United States)

    Voronin, Lois M.; Cauller, Stephen J.

    2017-07-31

    Elevated concentrations of nitrogen in groundwater that discharges to surface-water bodies can degrade surface-water quality and habitats in the New Jersey Coastal Plain. An analysis of groundwater flow in the Kirkwood-Cohansey aquifer system and deeper confined aquifers that underlie the Barnegat Bay–Little Egg Harbor (BB-LEH) watershed and estuary was conducted by using groundwater-flow simulation, in conjunction with a particle-tracking routine, to provide estimates of groundwater flow paths and travel times to streams and the BB-LEH estuary.Water-quality data from the Ambient Groundwater Quality Monitoring Network, a long-term monitoring network of wells distributed throughout New Jersey, were used to estimate the initial nitrogen concentration in recharge for five different land-use classes—agricultural cropland or pasture, agricultural orchard or vineyard, urban non-residential, urban residential, and undeveloped. Land use at the point of recharge within the watershed was determined using a geographic information system (GIS). Flow path starting locations were plotted on land-use maps for 1930, 1973, 1986, 1997, and 2002. Information on the land use at the time and location of recharge, time of travel to the discharge location, and the point of discharge were determined for each simulated flow path. Particle-tracking analysis provided the link from the point of recharge, along the particle flow path, to the point of discharge, and the particle travel time. The travel time of each simulated particle established the recharge year. Land use during the year of recharge was used to define the nitrogen concentration associated with each flow path. The recharge-weighted average nitrogen concentration for all flow paths that discharge to the Toms River upstream from streamflow-gaging station 01408500 or to the BB-LEH estuary was calculated.Groundwater input into the Barnegat Bay–Little Egg Harbor estuary from two main sources— indirect discharge from base

  2. Complexity in the validation of ground-water travel time in fractured flow and transport systems

    International Nuclear Information System (INIS)

    Davies, P.B.; Hunter, R.L.; Pickens, J.F.

    1991-01-01

    Ground-water travel time is a widely used concept in site assessment for radioactive waste disposal. While ground-water travel time was originally conceived to provide a simple performance measure for evaluating repository sites, its definition in many flow and transport environments is ambiguous. The U.S. Department of Energy siting guidelines (10 CFR 960) define ground-water travel time as the time required for a unit volume of water to travel between two locations, calculated by dividing travel-path length by the quotient of average ground-water flux and effective porosity. Defining a meaningful effective porosity in a fractured porous material is a significant problem. Although the Waste Isolation Pilot Plant (WIPP) is not subject to specific requirements for ground-water travel time, travel times have been computed under a variety of model assumptions. Recently completed model analyses for WIPP illustrate the difficulties in applying a ground-water travel-time performance measure to flow and transport in fractured, fully saturated flow systems. Computer code used: SWIFT II (flow and transport code). 4 figs., 12 refs

  3. SATURATED ZONE FLOW AND TRANSPORT MODEL ABSTRACTION

    International Nuclear Information System (INIS)

    B.W. ARNOLD

    2004-01-01

    The purpose of the saturated zone (SZ) flow and transport model abstraction task is to provide radionuclide-transport simulation results for use in the total system performance assessment (TSPA) for license application (LA) calculations. This task includes assessment of uncertainty in parameters that pertain to both groundwater flow and radionuclide transport in the models used for this purpose. This model report documents the following: (1) The SZ transport abstraction model, which consists of a set of radionuclide breakthrough curves at the accessible environment for use in the TSPA-LA simulations of radionuclide releases into the biosphere. These radionuclide breakthrough curves contain information on radionuclide-transport times through the SZ. (2) The SZ one-dimensional (I-D) transport model, which is incorporated in the TSPA-LA model to simulate the transport, decay, and ingrowth of radionuclide decay chains in the SZ. (3) The analysis of uncertainty in groundwater-flow and radionuclide-transport input parameters for the SZ transport abstraction model and the SZ 1-D transport model. (4) The analysis of the background concentration of alpha-emitting species in the groundwater of the SZ

  4. Simulation of ground-water flow and land subsidence in the Antelope Valley ground-water basin, California

    Science.gov (United States)

    Leighton, David A.; Phillips, Steven P.

    2003-01-01

    ground-water development have eliminated the natural sources of discharge, and pumping for agricultural and urban uses have become the primary source of discharge from the ground-water system. Infiltration of return flows from agricultural irrigation has become an important source of recharge to the aquifer system. The ground-water flow model of the basin was discretized horizontally into a grid of 43 rows and 60 columns of square cells 1 mile on a side, and vertically into three layers representing the upper, middle, and lower aquifers. Faults that were thought to act as horizontal-flow barriers were simulated in the model. The model was calibrated to simulate steady-state conditions, represented by 1915 water levels and transient-state conditions during 1915-95 using water-level and subsidence data. Initial estimates of the aquifer-system properties and stresses were obtained from a previously published numerical model of the Antelope Valley ground-water basin; estimates also were obtained from recently collected hydrologic data and from results of simulations of ground-water flow and land subsidence models of the Edwards Air Force Base area. Some of these initial estimates were modified during model calibration. Ground-water pumpage for agriculture was estimated on the basis of irrigated crop acreage and crop consumptive-use data. Pumpage for public supply, which is metered, was compiled and entered into a database used for this study. Estimated annual pumpage peaked at 395,000 acre-feet (acre-ft) in 1952 and then declined because of declining agricultural production. Recharge from irrigation-return flows was estimated to be 30 percent of agricultural pumpage; the irrigation-return flows were simulated as recharge to the regional water table 10 years following application at land surface. The annual quantity of natural recharge initially was based on estimates from previous studies. During model calibration, natural recharge was reduced from the initial

  5. Applying Dispersive Changes to Lagrangian Particles in Groundwater Transport Models

    Science.gov (United States)

    Konikow, Leonard F.

    2010-01-01

    Method-of-characteristics groundwater transport models require that changes in concentrations computed within an Eulerian framework to account for dispersion be transferred to moving particles used to simulate advective transport. A new algorithm was developed to accomplish this transfer between nodal values and advecting particles more precisely and realistically compared to currently used methods. The new method scales the changes and adjustments of particle concentrations relative to limiting bounds of concentration values determined from the population of adjacent nodal values. The method precludes unrealistic undershoot or overshoot for concentrations of individual particles. In the new method, if dispersion causes cell concentrations to decrease during a time step, those particles in the cell having the highest concentration will decrease the most, and those with the lowest concentration will decrease the least. The converse is true if dispersion is causing concentrations to increase. Furthermore, if the initial concentration on a particle is outside the range of the adjacent nodal values, it will automatically be adjusted in the direction of the acceptable range of values. The new method is inherently mass conservative. ?? US Government 2010.

  6. Reliability Analyses of Groundwater Pollutant Transport

    Energy Technology Data Exchange (ETDEWEB)

    Dimakis, Panagiotis

    1997-12-31

    This thesis develops a probabilistic finite element model for the analysis of groundwater pollution problems. Two computer codes were developed, (1) one using finite element technique to solve the two-dimensional steady state equations of groundwater flow and pollution transport, and (2) a first order reliability method code that can do a probabilistic analysis of any given analytical or numerical equation. The two codes were connected into one model, PAGAP (Probability Analysis of Groundwater And Pollution). PAGAP can be used to obtain (1) the probability that the concentration at a given point at a given time will exceed a specified value, (2) the probability that the maximum concentration at a given point will exceed a specified value and (3) the probability that the residence time at a given point will exceed a specified period. PAGAP could be used as a tool for assessment purposes and risk analyses, for instance the assessment of the efficiency of a proposed remediation technique or to study the effects of parameter distribution for a given problem (sensitivity study). The model has been applied to study the greatest self sustained, precipitation controlled aquifer in North Europe, which underlies Oslo`s new major airport. 92 refs., 187 figs., 26 tabs.

  7. Simulation of reactive geochemical transport in groundwater using a semi-analytical screening model

    Science.gov (United States)

    McNab, Walt W.

    1997-10-01

    A reactive geochemical transport model, based on a semi-analytical solution to the advective-dispersive transport equation in two dimensions, is developed as a screening tool for evaluating the impact of reactive contaminants on aquifer hydrogeochemistry. Because the model utilizes an analytical solution to the transport equation, it is less computationally intensive than models based on numerical transport schemes, is faster, and it is not subject to numerical dispersion effects. Although the assumptions used to construct the model preclude consideration of reactions between the aqueous and solid phases, thermodynamic mineral saturation indices are calculated to provide qualitative insight into such reactions. Test problems involving acid mine drainage and hydrocarbon biodegradation signatures illustrate the utility of the model in simulating essential hydrogeochemical phenomena.

  8. Simulating Groundwater Dynamics across the Contiguous United States Using MODFLOW-OWHM

    Science.gov (United States)

    Alattar, M.; Troy, T. J.; Russo, T. A.

    2017-12-01

    Groundwater is a critical water resource for irrigation, industry, and domestic water supply. Because of the importance of groundwater, especially for agriculture water supply, many regional studies have been implemented to understand groundwater dynamics, to protect groundwater resources, and to support more efficient management of surface and groundwater supplies to meet the water demands. While these regional studies provide invaluable insights into local problems, it is difficult to understand the state of America's water supplies holistically to understand how irrigation, pumping, and climate determine groundwater availability. To fill this gap, we use MODFLOW-OWHM to simulate and analyze groundwater flow across the United States from 1950 through 2010 at a monthly resolution. The model estimates the irrigation demand by crop type, pumping rates from groundwater wells, and groundwater availability and water levels. This allows us to analyze the impact of crop choices and on groundwater pumping as well as surface water withdrawals. The model is calibrated and validated across the contiguous United States with parameter sensitivity analysis. Because of the study region size, climate conditions vary temporally and spatially based on the mean climate and phenomena such as El Niño and La Niña. We do model experiments to analyze how this climate variability can affect recharge and water table depths and how irrigated crop choices impact surface and ground water sustainability. These model simulations have the potential to inform water resources management at a range of spatial scales.

  9. Uncertainty in simulated groundwater-quality trends in transient flow

    Science.gov (United States)

    Starn, J. Jeffrey; Bagtzoglou, Amvrossios; Robbins, Gary A.

    2013-01-01

    In numerical modeling of groundwater flow, the result of a given solution method is affected by the way in which transient flow conditions and geologic heterogeneity are simulated. An algorithm is demonstrated that simulates breakthrough curves at a pumping well by convolution-based particle tracking in a transient flow field for several synthetic basin-scale aquifers. In comparison to grid-based (Eulerian) methods, the particle (Lagrangian) method is better able to capture multimodal breakthrough caused by changes in pumping at the well, although the particle method may be apparently nonlinear because of the discrete nature of particle arrival times. Trial-and-error choice of number of particles and release times can perhaps overcome the apparent nonlinearity. Heterogeneous aquifer properties tend to smooth the effects of transient pumping, making it difficult to separate their effects in parameter estimation. Porosity, a new parameter added for advective transport, can be accurately estimated using both grid-based and particle-based methods, but predictions can be highly uncertain, even in the simple, nonreactive case.

  10. Guidelines for selecting codes for ground-water transport modeling of low-level waste burial sites. Executive summary

    International Nuclear Information System (INIS)

    Simmons, C.S.; Cole, C.R.

    1985-05-01

    This document was written to provide guidance to managers and site operators on how ground-water transport codes should be selected for assessing burial site performance. There is a need for a formal approach to selecting appropriate codes from the multitude of potentially useful ground-water transport codes that are currently available. Code selection is a problem that requires more than merely considering mathematical equation-solving methods. These guidelines are very general and flexible and are also meant for developing systems simulation models to be used to assess the environmental safety of low-level waste burial facilities. Code selection is only a single aspect of the overall objective of developing a systems simulation model for a burial site. The guidance given here is mainly directed toward applications-oriented users, but managers and site operators need to be familiar with this information to direct the development of scientifically credible and defensible transport assessment models. Some specific advice for managers and site operators on how to direct a modeling exercise is based on the following five steps: identify specific questions and study objectives; establish costs and schedules for achieving answers; enlist the aid of professional model applications group; decide on approach with applications group and guide code selection; and facilitate the availability of site-specific data. These five steps for managers/site operators are discussed in detail following an explanation of the nine systems model development steps, which are presented first to clarify what code selection entails

  11. Acid groundwater in an anoxic aquifer: Reactive transport modelling of buffering processes

    International Nuclear Information System (INIS)

    Franken, Gudrun; Postma, Dieke; Duijnisveld, Wilhelmus H.M.; Boettcher, Juergen; Molson, John

    2009-01-01

    The acidification of groundwater, due to acid rain, was investigated in a Quaternary sandy aquifer in the Fuhrberger Feld, near Hannover, Germany. The groundwater, recharged through an area covered by a coniferous forest, had a pH in the range 4-5 down to a depth of 5 m. The evolution in groundwater chemistry along the flow path was investigated in a transect of multisamplers. A 2D groundwater flow model was established delineating the groundwater flow field and a groundwater flow velocity of around 80 m/a along the flow path was derived. Speciation calculations showed the groundwater to be close to equilibrium with the mineral jurbanite (AlOHSO 4 ) over the pH range 4.0-6.5. This suggests an accumulation of acid rain derived SO 4 2- in the aquifer sediment during the decades with high atmospheric S deposition. The groundwater has a pH of around 4.5 in the upstream part of the flow path increasing to near 6 further downstream. 1D reactive transport modelling, using PHREEQC, was used to analyze different combinations of buffering processes. The first model contains ion exchange in combination with jurbanite dissolution. At the ion exchange front Al 3+ is adsorbed leading to the dissolution of jurbanite and an increase in pH. Comparison with field data showed that the simulated increases in pH and alkalinity are much lower than observed in the field. The second model includes organic matter degradation. In addition to ion exchange and jurbanite dissolution, the model included the reduction of SO 4 2- and Fe-oxides as well as the precipitation of Fe sulfide. This model matches the field data well and illustrates the importance of redox processes for pH buffering in the Fuhrberg aquifer. The current progress of the acidification front is about 4 m/a. This corresponds to an average value of 150 a of acid input, which covers large historical variations. Remediation is expected to take the same time span because it requires desorption and neutralization of adsorbed Al 3

  12. Groundwater simulation and management models for the upper Klamath Basin, Oregon and California

    Science.gov (United States)

    Gannett, Marshall W.; Wagner, Brian J.; Lite, Kenneth E.

    2012-01-01

    The upper Klamath Basin encompasses about 8,000 square miles, extending from the Cascade Range east to the Basin and Range geologic province in south-central Oregon and northern California. The geography of the basin is dominated by forested volcanic uplands separated by broad interior basins. Most of the interior basins once held broad shallow lakes and extensive wetlands, but most of these areas have been drained or otherwise modified and are now cultivated. Major parts of the interior basins are managed as wildlife refuges, primarily for migratory waterfowl. The permeable volcanic bedrock of the upper Klamath Basin hosts a substantial regional groundwater system that provides much of the flow to major streams and lakes that, in turn, provide water for wildlife habitat and are the principal source of irrigation water for the basin's agricultural economy. Increased allocation of surface water for endangered species in the past decade has resulted in increased groundwater pumping and growing interest in the use of groundwater for irrigation. The potential effects of increased groundwater pumping on groundwater levels and discharge to springs and streams has caused concern among groundwater users, wildlife and Tribal interests, and State and Federal resource managers. To provide information on the potential impacts of increased groundwater development and to aid in the development of a groundwater management strategy, the U.S. Geological Survey, in collaboration with the Oregon Water Resources Department and the Bureau of Reclamation, has developed a groundwater model that can simulate the response of the hydrologic system to these new stresses. The groundwater model was developed using the U.S. Geological Survey MODFLOW finite-difference modeling code and calibrated using inverse methods to transient conditions from 1989 through 2004 with quarterly stress periods. Groundwater recharge and agricultural and municipal pumping are specified for each stress period. All

  13. Surrogate model approach for improving the performance of reactive transport simulations

    Science.gov (United States)

    Jatnieks, Janis; De Lucia, Marco; Sips, Mike; Dransch, Doris

    2016-04-01

    Reactive transport models can serve a large number of important geoscientific applications involving underground resources in industry and scientific research. It is common for simulation of reactive transport to consist of at least two coupled simulation models. First is a hydrodynamics simulator that is responsible for simulating the flow of groundwaters and transport of solutes. Hydrodynamics simulators are well established technology and can be very efficient. When hydrodynamics simulations are performed without coupled geochemistry, their spatial geometries can span millions of elements even when running on desktop workstations. Second is a geochemical simulation model that is coupled to the hydrodynamics simulator. Geochemical simulation models are much more computationally costly. This is a problem that makes reactive transport simulations spanning millions of spatial elements very difficult to achieve. To address this problem we propose to replace the coupled geochemical simulation model with a surrogate model. A surrogate is a statistical model created to include only the necessary subset of simulator complexity for a particular scenario. To demonstrate the viability of such an approach we tested it on a popular reactive transport benchmark problem that involves 1D Calcite transport. This is a published benchmark problem (Kolditz, 2012) for simulation models and for this reason we use it to test the surrogate model approach. To do this we tried a number of statistical models available through the caret and DiceEval packages for R, to be used as surrogate models. These were trained on randomly sampled subset of the input-output data from the geochemical simulation model used in the original reactive transport simulation. For validation we use the surrogate model to predict the simulator output using the part of sampled input data that was not used for training the statistical model. For this scenario we find that the multivariate adaptive regression splines

  14. Numerical Modeling for the Solute Uptake from Groundwater by Plants-Plant Uptake Package

    OpenAIRE

    El-Sayed, Amr A.

    2006-01-01

    A numerical model is presented to describe solute transport in groundwater coupled to sorption by plant roots, translocation into plant stems, and finally evapotranspiration. The conceptual model takes into account both Root Concentration Factor, RCF, and Transpiration Stream Concentration Factor, TSCF for chemicals which are a function of Kow. A similar technique used to simulate the solute transport in groundwater to simulate sorption and plant uptake is used. The mathematical equation is s...

  15. Simulation of Groundwater Flow and Migration of the Radioactive Cobalt-60 from LAMA Nuclear Facility-Iraq

    Directory of Open Access Journals (Sweden)

    Thair Sharif Khayyun

    2018-02-01

    Full Text Available This study provides a simulation of groundwater flow and advective-dispersive migration of radioactive Co-60 through an aquifer with three layers, which release or leak to groundwater from the Active Metallurgy Testing Laboratory (LAMA Nuclear Facility-Iraq due to the nuclear accident scenario. Processing Modflow for windows (PMWIN and Modular Three-Dimensional Multispecies Transport (MT3DMS Models were used for this purpose. The study area and the contaminated area were 12.7 km2 and 0.005625 km2, respectively. Water levels of the groundwater have been measured in six monitoring wells. The simulation time was assumed to have started in 2016. The PMWIN model simulated the flow for two scenarios of water level in Tigris River (average and minimum water levels. The MT3DMS model simulated 10 years of plume travel, beginning in 2016. The simulated Co-60 concentrations after five years of travel were 32.34 and 34.44 μg/m3 for the two scenarios. The maximum predicted Co-60 concentrations at the end of Year 10 were 34.86 and 37.31 μg/m3, respectively. The sensitivity analysis showed that the simulated hydraulic heads in the observation wells and the simulated plume of Co-60 were highly sensitive to changes in the effective porosity but less sensitive to changes in other parameters of the dispersion and chemical reaction processes. The time necessary to reach steady state condition was predicted to be approximately 16 years. The contaminated area was isolated by using remedial process which is represented by three fully penetrating pumping wells with a suitable flow rate (0.045 m3/s for controlling the movement of Co-60 pollutant.

  16. Shallow groundwater in the Matanuska-Susitna Valley, Alaska—Conceptualization and simulation of flow

    Science.gov (United States)

    Kikuchi, Colin P.

    2013-01-01

    The Matanuska-Susitna Valley is in the Upper Cook Inlet Basin and is currently undergoing rapid population growth outside of municipal water and sewer service areas. In response to concerns about the effects of increasing water use on future groundwater availability, a study was initiated between the Alaska Department of Natural Resources and the U.S. Geological Survey. The goals of the study were (1) to compile existing data and collect new data to support hydrogeologic conceptualization of the study area, and (2) to develop a groundwater flow model to simulate flow dynamics important at the regional scale. The purpose of the groundwater flow model is to provide a scientific framework for analysis of regional-scale groundwater availability. To address the first study goal, subsurface lithologic data were compiled into a database and were used to construct a regional hydrogeologic framework model describing the extent and thickness of hydrogeologic units in the Matanuska-Susitna Valley. The hydrogeologic framework model synthesizes existing maps of surficial geology and conceptual geochronologies developed in the study area with the distribution of lithologies encountered in hundreds of boreholes. The geologic modeling package Geological Surveying and Investigation in Three Dimensions (GSI3D) was used to construct the hydrogeologic framework model. In addition to characterizing the hydrogeologic framework, major groundwater-budget components were quantified using several different techniques. A land-surface model known as the Deep Percolation Model was used to estimate in-place groundwater recharge across the study area. This model incorporates data on topography, soils, vegetation, and climate. Model-simulated surface runoff was consistent with observed streamflow at U.S. Geological Survey streamgages. Groundwater withdrawals were estimated on the basis of records from major water suppliers during 2004-2010. Fluxes between groundwater and surface water were

  17. Impact of colloids on uranium transport in groundwater applied to the Aube radioactive waste disposal

    International Nuclear Information System (INIS)

    Le Cointe, Pierre

    2011-01-01

    The presence of colloids, known vectors of radionuclides and chemical contaminants in groundwater, has been identified in groundwater at the Aube radioactive waste disposal in 2004. This thesis aims to characterize these colloids, and to determine their potential impact in the transport of Uranium, chosen as the element of interest for this study. The identified 60 nm in diameter clay colloids and the fulvic and humic acids can move in Aptian groundwater, as indirectly evidenced by column experiments. A feasibility study of a in situ test has been done through a transport modeling to confirm the colloid mobility at the field scale. Using the conditions of the study, the clay colloids do not influence Uranium transport. Even with the greatest concentration assumed on site, they have a very limited impact on the mobilization of Uranium, in the pH range measured on site. On the contrary, the organic colloids, despite their low concentration, can facilitate Uranium transport, the uranyl - organic acid chemical bond being exceptionally strong. Therefore their low concentration in groundwater makes their impact on uranium mobility equally insignificant. (author)

  18. Phast4Windows: A 3D graphical user interface for the reactive-transport simulator PHAST

    Science.gov (United States)

    Charlton, Scott R.; Parkhurst, David L.

    2013-01-01

    Phast4Windows is a Windows® program for developing and running groundwater-flow and reactive-transport models with the PHAST simulator. This graphical user interface allows definition of grid-independent spatial distributions of model properties—the porous media properties, the initial head and chemistry conditions, boundary conditions, and locations of wells, rivers, drains, and accounting zones—and other parameters necessary for a simulation. Spatial data can be defined without reference to a grid by drawing, by point-by-point definitions, or by importing files, including ArcInfo® shape and raster files. All definitions can be inspected, edited, deleted, moved, copied, and switched from hidden to visible through the data tree of the interface. Model features are visualized in the main panel of the interface, so that it is possible to zoom, pan, and rotate features in three dimensions (3D). PHAST simulates single phase, constant density, saturated groundwater flow under confined or unconfined conditions. Reactions among multiple solutes include mineral equilibria, cation exchange, surface complexation, solid solutions, and general kinetic reactions. The interface can be used to develop and run simple or complex models, and is ideal for use in the classroom, for analysis of laboratory column experiments, and for development of field-scale simulations of geochemical processes and contaminant transport.

  19. Study on Contaminant Transportation of a Typical Chemical Industry Park Based on GMS Software

    Science.gov (United States)

    Huang, LinXian; Liu, GuoZhen; Xing, LiTing; Liu, BenHua; Xu, ZhengHe; Yang, LiZhi; Zhu, HebgHua

    2018-03-01

    The groundwater solute transport model can effectively simulated the transport path, the transport scope, and the concentration of contaminant which can provide quantitative data for groundwater pollution repair and groundwater resource management. In this study, we selected biological modern technology research base of Shandong province as research objective and simulated the pollution characteristic of typicalcontaminant cis-1, 3-dichloropropene under different operating conditions by using GMS software.

  20. Combining numerical simulations with time-domain random walk for pathogen risk assessment in groundwater

    Science.gov (United States)

    Cvetkovic, V.; Molin, S.

    2012-02-01

    We present a methodology that combines numerical simulations of groundwater flow and advective transport in heterogeneous porous media with analytical retention models for computing the infection risk probability from pathogens in aquifers. The methodology is based on the analytical results presented in [1,2] for utilising the colloid filtration theory in a time-domain random walk framework. It is shown that in uniform flow, the results from the numerical simulations of advection yield comparable results as the analytical TDRW model for generating advection segments. It is shown that spatial variability of the attachment rate may be significant, however, it appears to affect risk in a different manner depending on if the flow is uniform or radially converging. In spite of the fact that numerous issues remain open regarding pathogen transport in aquifers on the field scale, the methodology presented here may be useful for screening purposes, and may also serve as a basis for future studies that would include greater complexity.

  1. A New Approach to Simulate Groundwater Table Dynamics and Its Validation in China

    Science.gov (United States)

    Lv, M.; Lu, H.; Dan, L.; Yang, K.

    2017-12-01

    The groundwater has very important role in hydrology-climate-human activity interaction. But the groundwater table dynamics currently is not well simulated in global-scale land surface models. Meanwhile, almost all groundwater schemes are adopting a specific yield method to estimate groundwater table, in which how to determine the proper specific yield value remains a big challenge. In this study, we developed a Soil Moisture Correlation (SMC) method to simulate groundwater table dynamics. We coupled SMC with a hydrological model (named as NEW) and compared it with the original model in which a specific yield method is used (named as CTL). Both NEW and CTL were tested in Tangnaihai Subbasin of Yellow River and Jialingjiang Subbasin along Yangtze River, where underground water is less impacted by human activities. The simulated discharges by NEW and CTL are compared against gauge observations. The comparison results reveal that after calibration both models are able to reproduce the discharge well. However, there is no parameter needed to be calibrated for SMC. It indicates that SMC method is more efficient and easy-to-use than the specific yield method. Since there is no direct groundwater table observation in these two basins, simulated groundwater table were compared with a global data set provided by Fan et al. (2013). Both NEW and CTL estimate lower depths than Fan does. Moreover, when comparing the variation of terrestrial water storage (TWS) derived from NEW with that observed by GRACE, good agreements were confirmed. It demonstrated that SMC method is able to reproduce groundwater level dynamics reliably.

  2. Unstable mixed convective transport in groundwater

    International Nuclear Information System (INIS)

    Schincariol, R.A.; Schwartz, F.W.

    1990-01-01

    This study is an experimental investigation of variable density groundwater flow in homogeneous and lenticular porous media. A solution of 500 mg/l Rhodamine WT dye served as the carrier for various concentrations of solute (NaCl) introduced into a two-dimensional flow tank at concentrations ranging from 1000 to 100,000 mg/l. At the scale of the experiments, mass transport depends upon both forced and free convection. In addition, density differences as low as 0.008 g/cm 3 (1000 mg/l NaCl) between a plume of dense water and ambient groundwater in homogeneous medium produces gravitational instabilities at realistic groundwater velocities. These instabilities are manifest by lobe-shaped protuberances that formed first along the bottom edge of the plume and later within the plume. As the density difference increases to 0.0015 g/cm 3 (2000 mg/l NaCl), 0.0037 g/cm 3 (5000 mg/l NaCl) or higher, this unstable mixing due to convective dispersion significantly alters the spreading process, resulting in a large degree of vertical spreading of the plume. In a lenticular medium the combination of convective dispersion and nonuniform flow due to heterogeneities results in relatively large dispersion. Scale considerations indicate that convective dispersion may provide an important component of mixing at the field scale. (Author) (30 refs., 12 figs., 3 tabs.)

  3. Achieving sustainable ground-water management by using GIS-integrated simulation tools: the EU H2020 FREEWAT platform

    Science.gov (United States)

    Rossetto, Rudy; De Filippis, Giovanna; Borsi, Iacopo; Foglia, Laura; Toegl, Anja; Cannata, Massimiliano; Neumann, Jakob; Vazquez-Sune, Enric; Criollo, Rotman

    2017-04-01

    In order to achieve sustainable and participated ground-water management, innovative software built on the integration of numerical models within GIS software is a perfect candidate to provide a full characterization of quantitative and qualitative aspects of ground- and surface-water resources maintaining the time and spatial dimension. The EU H2020 FREEWAT project (FREE and open source software tools for WATer resource management; Rossetto et al., 2015) aims at simplifying the application of EU water-related Directives through an open-source and public-domain, GIS-integrated simulation platform for planning and management of ground- and surface-water resources. The FREEWAT platform allows to simulate the whole hydrological cycle, coupling the power of GIS geo-processing and post-processing tools in spatial data analysis with that of process-based simulation models. This results in a modeling environment where large spatial datasets can be stored, managed and visualized and where several simulation codes (mainly belonging to the USGS MODFLOW family) are integrated to simulate multiple hydrological, hydrochemical or economic processes. So far, the FREEWAT platform is a large plugin for the QGIS GIS desktop software and it integrates the following capabilities: • the AkvaGIS module allows to produce plots and statistics for the analysis and interpretation of hydrochemical and hydrogeological data; • the Observation Analysis Tool, to facilitate the import, analysis and visualization of time-series data and the use of these data to support model construction and calibration; • groundwater flow simulation in the saturated and unsaturated zones may be simulated using MODFLOW-2005 (Harbaugh, 2005); • multi-species advective-dispersive transport in the saturated zone can be simulated using MT3DMS (Zheng & Wang, 1999); the possibility to simulate viscosity- and density-dependent flows is further accomplished through SEAWAT (Langevin et al., 2007); • sustainable

  4. Optimal groundwater remediation using artificial neural networks and the genetic algorithm

    Energy Technology Data Exchange (ETDEWEB)

    Rogers, Leah L. [Stanford Univ., CA (United States)

    1992-08-01

    An innovative computational approach for the optimization of groundwater remediation is presented which uses artificial neural networks (ANNs) and the genetic algorithm (GA). In this approach, the ANN is trained to predict an aspect of the outcome of a flow and transport simulation. Then the GA searches through realizations or patterns of pumping and uses the trained network to predict the outcome of the realizations. This approach has advantages of parallel processing of the groundwater simulations and the ability to ``recycle`` or reuse the base of knowledge formed by these simulations. These advantages offer reduction of computational burden of the groundwater simulations relative to a more conventional approach which uses nonlinear programming (NLP) with a quasi-newtonian search. Also the modular nature of this approach facilitates substitution of different groundwater simulation models.

  5. Optimal groundwater remediation using artificial neural networks and the genetic algorithm

    International Nuclear Information System (INIS)

    Rogers, L.L.

    1992-08-01

    An innovative computational approach for the optimization of groundwater remediation is presented which uses artificial neural networks (ANNs) and the genetic algorithm (GA). In this approach, the ANN is trained to predict an aspect of the outcome of a flow and transport simulation. Then the GA searches through realizations or patterns of pumping and uses the trained network to predict the outcome of the realizations. This approach has advantages of parallel processing of the groundwater simulations and the ability to ''recycle'' or reuse the base of knowledge formed by these simulations. These advantages offer reduction of computational burden of the groundwater simulations relative to a more conventional approach which uses nonlinear programming (NLP) with a quasi-newtonian search. Also the modular nature of this approach facilitates substitution of different groundwater simulation models

  6. VS2DRTI: Simulating Heat and Reactive Solute Transport in Variably Saturated Porous Media.

    Science.gov (United States)

    Healy, Richard W; Haile, Sosina S; Parkhurst, David L; Charlton, Scott R

    2018-01-29

    Variably saturated groundwater flow, heat transport, and solute transport are important processes in environmental phenomena, such as the natural evolution of water chemistry of aquifers and streams, the storage of radioactive waste in a geologic repository, the contamination of water resources from acid-rock drainage, and the geologic sequestration of carbon dioxide. Up to now, our ability to simulate these processes simultaneously with fully coupled reactive transport models has been limited to complex and often difficult-to-use models. To address the need for a simple and easy-to-use model, the VS2DRTI software package has been developed for simulating water flow, heat transport, and reactive solute transport through variably saturated porous media. The underlying numerical model, VS2DRT, was created by coupling the flow and transport capabilities of the VS2DT and VS2DH models with the equilibrium and kinetic reaction capabilities of PhreeqcRM. Flow capabilities include two-dimensional, constant-density, variably saturated flow; transport capabilities include both heat and multicomponent solute transport; and the reaction capabilities are a complete implementation of geochemical reactions of PHREEQC. The graphical user interface includes a preprocessor for building simulations and a postprocessor for visual display of simulation results. To demonstrate the simulation of multiple processes, the model is applied to a hypothetical example of injection of heated waste water to an aquifer with temperature-dependent cation exchange. VS2DRTI is freely available public domain software. © 2018, National Ground Water Association.

  7. Complexity in the validation of ground-water travel time in fractured flow and transport systems

    International Nuclear Information System (INIS)

    Davies, P.B; Hunter, R.L.; Pickens, J.F.

    1991-02-01

    Ground-water travel time is a widely used concept in site assessment for radioactive waste disposal. While ground-water travel time was originally conceived to provide a simple performance measure for evaluating repository sites, its definition in many flow and transport environments is ambiguous. The US Department of Energy siting guidelines (10 CFR 960) define ground-water travel time as the time required for a unit volume of water to travel between two locations, calculated by dividing travel-path length by the quotient of average ground-water flux and effective porosity. Defining a meaningful effective porosity in a fractured porous material is a significant problem. Although the Waste Isolation Pilot Plant (WIPP) is not subject to specific requirements for ground-water travel time, travel times have been computed under a variety of model assumptions. Recently completed model analyses for WIPP illustrate the difficulties in applying a ground-water travel-time performance measure to flow and transport in fractured, fully saturated flow systems. 12 refs., 4 figs

  8. Optimizing the design of large-scale ground-coupled heat pump systems using groundwater and heat transport modeling

    Energy Technology Data Exchange (ETDEWEB)

    Fujii, H.; Itoi, R.; Fujii, J. [Kyushu University, Fukuoka (Japan). Faculty of Engineering, Department of Earth Resources Engineering; Uchida, Y. [Geological Survey of Japan, Tsukuba (Japan)

    2005-06-01

    In order to predict the long-term performance of large-scale ground-coupled heat pump (GCHP) systems, it is necessary to take into consideration well-to-well interference, especially in the presence of groundwater flow. A mass and heat transport model was developed to simulate the behavior of this type of system in the Akita Plain, northern Japan. The model was used to investigate different operational schemes and to maximize the heat extraction rate from the GCHP system. (author)

  9. GLOBAL RANDOM WALK SIMULATIONS FOR SENSITIVITY AND UNCERTAINTY ANALYSIS OF PASSIVE TRANSPORT MODELS

    Directory of Open Access Journals (Sweden)

    Nicolae Suciu

    2011-07-01

    Full Text Available The Global Random Walk algorithm (GRW performs a simultaneoustracking on a fixed grid of huge numbers of particles at costscomparable to those of a single-trajectory simulation by the traditional Particle Tracking (PT approach. Statistical ensembles of GRW simulations of a typical advection-dispersion process in groundwater systems with randomly distributed spatial parameters are used to obtain reliable estimations of the input parameters for the upscaled transport model and of their correlations, input-output correlations, as well as full probability distributions of the input and output parameters.

  10. Real - time Dynamic Simulation and Prediction of Groundwater in Typical Arid Area Based on SPASS Improvement

    Science.gov (United States)

    Wang, Xiao-ming

    2018-03-01

    The establishment of traditional groundwater numerical simulation model, parameter identification and inspection process, especially the water level fitting and the actual observation of the value obtained compared to a large error. Based on the SPASS software, a large number of statistical analysis of the numerical simulation results show that the complexity of the terrain in the study area, the distribution of lithology and the influence of the parameters on the groundwater level in the study area have great influence on the groundwater level. Through the multi-factor analysis and adjustment, the simulated groundwater flow and the actual observation are similar. Then, the final result is taken as the standard value, and the groundwater in the study area is simulated and predicted in real time. The simulation results provide technical support for the further development and utilization of the local water resources.

  11. Integrating Satellite Image Identification and River Routing Simulation into the Groundwater Simulation of Chou-Shui Basin

    Science.gov (United States)

    Yao, Y.; Yang, S.; Chen, Y.; Chang, L.; Chiang, C.; Huang, C.; Chen, J.

    2012-12-01

    Many groundwater simulation models have been developed for Chou-Shui River alluvial fan which is one of the most important groundwater areas in Taiwan. However, the exchange quantity between Chou-Shui River, the major river in this area, and the groundwater system itself is seldom studied. In this study, the exchange is evaluated using a river package (RIV) in the groundwater simulation model, MODFLOW 2000. Several critical parameters and variables used in RIV such as wet area and river level for each cell below the Chou-Shui River are respectively determined by satellite image identification and HEC-RAS simulation. The monthly average of river levels obtained from four stations include Chang-Yun Bridge, Xi-Bin Bridge, Chi-Chiang Bridge and Si-Jou Bridge during 2008 and the river cross-section measured on December 2007 are used in the construction of HEC-RAS model. Four FORMOSAT multispectral satellite images respectively obtained on January 2008, April 2008, July 2008, and November 2008 are used to identify the wet area of Chou-Shui River during different seasons. Integrating the simulation level provided by HEC-RAS and the identification result are used as the assignment of RIV. First, based on the simulation results of HEC-RAS, the water level differences between flooding period and draught period are 1.4 (m) and 2.0 (m) for Xi-Bin Bridge station (downstream) and Chang-Yun Bridge station (upstream) respectively. Second, based on the identified results, the wet areas for four seasons are 24, 24, 40 and 12 (km2) respectively. The variation range of areas in 2008 is huge that the area for winter is just 30% of the area for summer. Third, based on the simulation of MODFLOW 2000 and RIV, the exchange between the river and the groundwater system is 414 million cubic meters which contains 526 for recharge to river and 112 for discharging from river during 2008. The total recharge includes river exchange and recharge from non-river area is 2023 million cubic meters. The

  12. Modeling uranium transport in acidic contaminated groundwater with base addition

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Fan [Institute of Tibetan Plateau Research, Chinese Academy of Sciences; Luo, Wensui [ORNL; Parker, Jack C. [University of Tennessee, Knoxville (UTK); Brooks, Scott C [ORNL; Watson, David B [ORNL; Jardine, Philip [University of Tennessee, Knoxville (UTK); Gu, Baohua [ORNL

    2011-01-01

    This study investigates reactive transport modeling in a column of uranium(VI)-contaminated sediments with base additions in the circulating influent. The groundwater and sediment exhibit oxic conditions with low pH, high concentrations of NO{sub 3}{sup -}, SO{sub 4}{sup 2-}, U and various metal cations. Preliminary batch experiments indicate that additions of strong base induce rapid immobilization of U for this material. In the column experiment that is the focus of the present study, effluent groundwater was titrated with NaOH solution in an inflow reservoir before reinjection to gradually increase the solution pH in the column. An equilibrium hydrolysis, precipitation and ion exchange reaction model developed through simulation of the preliminary batch titration experiments predicted faster reduction of aqueous Al than observed in the column experiment. The model was therefore modified to consider reaction kinetics for the precipitation and dissolution processes which are the major mechanism for Al immobilization. The combined kinetic and equilibrium reaction model adequately described variations in pH, aqueous concentrations of metal cations (Al, Ca, Mg, Sr, Mn, Ni, Co), sulfate and U(VI). The experimental and modeling results indicate that U(VI) can be effectively sequestered with controlled base addition due to sorption by slowly precipitated Al with pH-dependent surface charge. The model may prove useful to predict field-scale U(VI) sequestration and remediation effectiveness.

  13. Modeling uranium transport in acidic contaminated groundwater with base addition

    International Nuclear Information System (INIS)

    Zhang Fan; Luo Wensui; Parker, Jack C.; Brooks, Scott C.; Watson, David B.; Jardine, Philip M.; Gu Baohua

    2011-01-01

    This study investigates reactive transport modeling in a column of uranium(VI)-contaminated sediments with base additions in the circulating influent. The groundwater and sediment exhibit oxic conditions with low pH, high concentrations of NO 3 - , SO 4 2- , U and various metal cations. Preliminary batch experiments indicate that additions of strong base induce rapid immobilization of U for this material. In the column experiment that is the focus of the present study, effluent groundwater was titrated with NaOH solution in an inflow reservoir before reinjection to gradually increase the solution pH in the column. An equilibrium hydrolysis, precipitation and ion exchange reaction model developed through simulation of the preliminary batch titration experiments predicted faster reduction of aqueous Al than observed in the column experiment. The model was therefore modified to consider reaction kinetics for the precipitation and dissolution processes which are the major mechanism for Al immobilization. The combined kinetic and equilibrium reaction model adequately described variations in pH, aqueous concentrations of metal cations (Al, Ca, Mg, Sr, Mn, Ni, Co), sulfate and U(VI). The experimental and modeling results indicate that U(VI) can be effectively sequestered with controlled base addition due to sorption by slowly precipitated Al with pH-dependent surface charge. The model may prove useful to predict field-scale U(VI) sequestration and remediation effectiveness.

  14. Modeling uranium transport in acidic contaminated groundwater with base addition

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Fan, E-mail: zhangfan@itpcas.ac.cn [Key Laboratory of Tibetan Environment Changes and Land Surface Processes, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, P.O. Box 2871, Beijing, 100085 (China); Luo Wensui [Institute of Urban Environment, Chinese Academy of Sciences, Xiamen, 361021 (China); Parker, Jack C. [Institute for a Secure and Sustainable Environment, Department of Civil and Environmental Engineering, University of Tennessee, Knoxville, TN 37996 (United States); Brooks, Scott C.; Watson, David B. [Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Jardine, Philip M. [Biosystems Engineering and Soil Science Department, University of Tennessee, Knoxville, TN 37996 (United States); Gu Baohua [Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States)

    2011-06-15

    This study investigates reactive transport modeling in a column of uranium(VI)-contaminated sediments with base additions in the circulating influent. The groundwater and sediment exhibit oxic conditions with low pH, high concentrations of NO{sub 3}{sup -}, SO{sub 4}{sup 2-}, U and various metal cations. Preliminary batch experiments indicate that additions of strong base induce rapid immobilization of U for this material. In the column experiment that is the focus of the present study, effluent groundwater was titrated with NaOH solution in an inflow reservoir before reinjection to gradually increase the solution pH in the column. An equilibrium hydrolysis, precipitation and ion exchange reaction model developed through simulation of the preliminary batch titration experiments predicted faster reduction of aqueous Al than observed in the column experiment. The model was therefore modified to consider reaction kinetics for the precipitation and dissolution processes which are the major mechanism for Al immobilization. The combined kinetic and equilibrium reaction model adequately described variations in pH, aqueous concentrations of metal cations (Al, Ca, Mg, Sr, Mn, Ni, Co), sulfate and U(VI). The experimental and modeling results indicate that U(VI) can be effectively sequestered with controlled base addition due to sorption by slowly precipitated Al with pH-dependent surface charge. The model may prove useful to predict field-scale U(VI) sequestration and remediation effectiveness.

  15. Impacts of physical and chemical aquifer heterogeneity on basin-scale solute transport: Vulnerability of deep groundwater to arsenic contamination in Bangladesh

    Science.gov (United States)

    Michael, Holly A.; Khan, Mahfuzur R.

    2016-12-01

    Aquifer heterogeneity presents a primary challenge in predicting the movement of solutes in groundwater systems. The problem is particularly difficult on very large scales, across which permeability, chemical properties, and pumping rates may vary by many orders of magnitude and data are often sparse. An example is the fluvio-deltaic aquifer system of Bangladesh, where naturally-occurring arsenic (As) exists over tens of thousands of square kilometers in shallow groundwater. Millions of people in As-affected regions rely on deep (≥150 m) groundwater as a safe source of drinking water. The sustainability of this resource has been evaluated with models using effective properties appropriate for a basin-scale contamination problem, but the extent to which preferential flow affects the timescale of downward migration of As-contaminated shallow groundwater is unknown. Here we embed detailed, heterogeneous representations of hydraulic conductivity (K), pumping rates, and sorptive properties (Kd) within a basin-scale numerical groundwater flow and solute transport model to evaluate their effects on vulnerability and deviations from simulations with homogeneous representations in two areas with different flow systems. Advective particle tracking shows that heterogeneity in K does not affect average travel times from shallow zones to 150 m depth, but the travel times of the fastest 10% of particles decreases by a factor of ∼2. Pumping distributions do not strongly affect travel times if irrigation remains shallow, but increases in the deep pumping rate substantially reduce travel times. Simulation of advective-dispersive transport with sorption shows that deep groundwater is protected from contamination over a sustainable timeframe (>1000 y) if the spatial distribution of Kd is uniform. However, if only low-K sediments sorb As, 30% of the aquifer is not protected. Results indicate that sustainable management strategies in the Bengal Basin should consider impacts of both

  16. Using travel times to simulate multi-dimensional bioreactive transport in time-periodic flows.

    Science.gov (United States)

    Sanz-Prat, Alicia; Lu, Chuanhe; Finkel, Michael; Cirpka, Olaf A

    2016-04-01

    In travel-time models, the spatially explicit description of reactive transport is replaced by associating reactive-species concentrations with the travel time or groundwater age at all locations. These models have been shown adequate for reactive transport in river-bank filtration under steady-state flow conditions. Dynamic hydrological conditions, however, can lead to fluctuations of infiltration velocities, putting the validity of travel-time models into question. In transient flow, the local travel-time distributions change with time. We show that a modified version of travel-time based reactive transport models is valid if only the magnitude of the velocity fluctuates, whereas its spatial orientation remains constant. We simulate nonlinear, one-dimensional, bioreactive transport involving oxygen, nitrate, dissolved organic carbon, aerobic and denitrifying bacteria, considering periodic fluctuations of velocity. These fluctuations make the bioreactive system pulsate: The aerobic zone decreases at times of low velocity and increases at those of high velocity. For the case of diurnal fluctuations, the biomass concentrations cannot follow the hydrological fluctuations and a transition zone containing both aerobic and obligatory denitrifying bacteria is established, whereas a clear separation of the two types of bacteria prevails in the case of seasonal velocity fluctuations. We map the 1-D results to a heterogeneous, two-dimensional domain by means of the mean groundwater age for steady-state flow in both domains. The mapped results are compared to simulation results of spatially explicit, two-dimensional, advective-dispersive-bioreactive transport subject to the same relative fluctuations of velocity as in the one-dimensional model. The agreement between the mapped 1-D and the explicit 2-D results is excellent. We conclude that travel-time models of nonlinear bioreactive transport are adequate in systems of time-periodic flow if the flow direction does not change

  17. Simulating the impact of climate change on the groundwater resources of the Magdalen Islands, Québec, Canada

    Directory of Open Access Journals (Sweden)

    Jean-Michel Lemieux

    2015-03-01

    Full Text Available Study region: This study is conducted in the Magdalen Islands (Québec, Canada, a small archipelago located in the Gulf of St. Lawrence. Study focus: This work was undertaken to support the design of a long-term groundwater monitoring network and for the sustainable management of groundwater resources. This study relies mostly on the compilation of existing data, but additional field work has also been carried out, allowing for the first time in the Magdalen Islands, direct observation of the depth and shape of the transition zone between freshwater and seawater under natural conditions. Simulations were conducted along a 2D cross-section on Grande Entrée Island in order to assess the individual and combined impacts of sea-level rise, coastal erosion and decreased groundwater recharge on the position of the saltwater–freshwater interface. The simulations were performed considering variable-density flow and solute transport under saturated-unsaturated conditions. The model was driven by observed and projected climate change scenarios to 2040 for the Magdalen Islands. New hydrological insights for the region: The simulation results show that among the three impacts considered, the most important is sea-level rise, followed by decreasing groundwater recharge and coastal erosion. When combined, these impacts cause the saltwater–freshwater interface to migrate inland over a distance of 37 m and to rise by 6.5 m near the coast to 3.1 m further inland, over a 28-year period. Keywords: Coastal aquifers, Seawater intrusion, Climate change, Magdalen Islands

  18. Reactive transport modeling of uranium 238 and radium 226 in groundwater of the Königstein uranium mine, Germany

    Science.gov (United States)

    Nitzsche, O.; Merkel, B.

    Knowledge of the transport behavior of radionuclides in groundwater is needed for both groundwater protection and remediation of abandoned uranium mines and milling sites. Dispersion, diffusion, mixing, recharge to the aquifer, and chemical interactions, as well as radioactive decay, should be taken into account to obtain reliable predictions on transport of primordial nuclides in groundwater. This paper demonstrates the need for carrying out rehabilitation strategies before closure of the Königstein in-situ leaching uranium mine near Dresden, Germany. Column experiments on drilling cores with uranium-enriched tap water provided data about the exchange behavior of uranium. Uranium breakthrough was observed after more than 20 pore volumes. This strong retardation is due to the exchange of positively charged uranium ions. The code TReAC is a 1-D, 2-D, and 3-D reactive transport code that was modified to take into account the radioactive decay of uranium and the most important daughter nuclides, and to include double-porosity flow. TReAC satisfactorily simulated the breakthrough curves of the column experiments and provided a first approximation of exchange parameters. Groundwater flow in the region of the Königstein mine was simulated using the FLOWPATH code. Reactive transport behavior was simulated with TReAC in one dimension along a 6000-m path line. Results show that uranium migration is relatively slow, but that due to decay of uranium, the concentration of radium along the flow path increases. Results are highly sensitive to the influence of double-porosity flow. Résumé La protection des eaux souterraines et la restauration des sites miniers et de prétraitement d'uranium abandonnés nécessitent de connaître le comportement des radionucléides au cours de leur transport dans les eaux souterraines. La dispersion, la diffusion, le mélange, la recharge de l'aquifère et les interactions chimiques, de même que la décroissance radioactive, doivent être

  19. Hydrogeologic Settings and Ground-Water Flow Simulations for Regional Studies of the Transport of Anthropogenic and Natural Contaminants to Public-Supply Wells - Studies Begun in 2001

    Science.gov (United States)

    Paschke, Suzanne S.

    2007-01-01

    This study of the Transport of Anthropogenic and Natural Contaminants to public-supply wells (TANC study) is being conducted as part of the U.S. Geological Survey National Water Quality Assessment (NAWQA) Program and was designed to increase understanding of the most important factors to consider in ground-water vulnerability assessments. The seven TANC studies that began in 2001 used retrospective data and ground-water flow models to evaluate hydrogeologic variables that affect aquifer susceptibility and vulnerability at a regional scale. Ground-water flow characteristics, regional water budgets, pumping-well information, and water-quality data were compiled from existing data and used to develop conceptual models of ground-water conditions for each study area. Steady-state regional ground-water flow models were used to represent the conceptual models, and advective particle-tracking simulations were used to compute areas contributing recharge and traveltimes from recharge to selected public-supply wells. Retrospective data and modeling results were tabulated into a relational database for future analysis. Seven study areas were selected to evaluate a range of hydrogeologic settings and management practices across the Nation: the Salt Lake Valley, Utah; the Eagle Valley and Spanish Springs Valley, Nevada; the San Joaquin Valley, California; the Northern Tampa Bay region, Florida; the Pomperaug River Basin, Connecticut; the Great Miami River Basin, Ohio; and the Eastern High Plains, Nebraska. This Professional Paper Chapter presents the hydrogeologic settings and documents the ground-water flow models for each of the NAWQA TANC regional study areas that began work in 2001. Methods used to compile retrospective data, determine contributing areas of public-supply wells, and characterize oxidation-reduction (redox) conditions also are presented. This Professional Paper Chapter provides the foundation for future susceptibility and vulnerability analyses in the TANC

  20. Land-Use Analysis and Simulated Effects of Land-Use Change and Aggregate Mining on Groundwater Flow in the South Platte River Valley, Brighton to Fort Lupton, Colorado

    Science.gov (United States)

    Arnold, L.R.; Mladinich, C.S.; Langer, W.H.; Daniels, J.S.

    2010-01-01

    Land use in the South Platte River valley between the cities of Brighton and Fort Lupton, Colo., is undergoing change as urban areas expand, and the extent of aggregate mining in the Brighton-Fort Lupton area is increasing as the demand for aggregate grows in response to urban development. To improve understanding of land-use change and the potential effects of land-use change and aggregate mining on groundwater flow, the U.S. Geological Survey, in cooperation with the cities of Brighton and Fort Lupton, analyzed socioeconomic and land-use trends and constructed a numerical groundwater flow model of the South Platte alluvial aquifer in the Brighton-Fort Lupton area. The numerical groundwater flow model was used to simulate (1) steady-state hydrologic effects of predicted land-use conditions in 2020 and 2040, (2) transient cumulative hydrologic effects of the potential extent of reclaimed aggregate pits in 2020 and 2040, (3) transient hydrologic effects of actively dewatered aggregate pits, and (4) effects of different hypothetical pit spacings and configurations on groundwater levels. The SLEUTH (Slope, Land cover, Exclusion, Urbanization, Transportation, and Hillshade) urban-growth modeling program was used to predict the extent of urban area in 2020 and 2040. Wetlands in the Brighton-Fort Lupton area were mapped as part of the study, and mapped wetland locations and areas of riparian herbaceous vegetation previously mapped by the Colorado Division of Wildlife were compared to simulation results to indicate areas where wetlands or riparian herbaceous vegetation might be affected by groundwater-level changes resulting from land-use change or aggregate mining. Analysis of land-use conditions in 1957, 1977, and 2000 indicated that the general distribution of irrigated land and non-irrigated land remained similar from 1957 to 2000, but both land uses decreased as urban area increased. Urban area increased about 165 percent from 1957 to 1977 and about 56 percent from

  1. Uncertainties in geologic disposal of high-level wastes - groundwater transport of radionuclides and radiological consequences

    International Nuclear Information System (INIS)

    Kocher, D.C.; Sjoreen, A.L.; Bard, C.S.

    1983-01-01

    The analysis for radionuclide transport in groundwater considers models and methods for characterizing (1) the present geologic environment and its future evolution due to natural geologic processes and to repository development and waste emplacement, (2) groundwater hydrology, (3) radionuclide geochemistry, and (4) the interactions among these phenomena. The discussion of groundwater transport focuses on the nature of the sources of uncertainty rather than on quantitative estimates of their magnitude, because of the lack of evidence that current models can provide realistic quantitative predictions of radionuclide transport in groundwater for expected repository environments. The analysis for the long-term health risk to man following releases of long-lived radionuclides to the biosphere is more quantitative and involves estimates of uncertainties in (1) radionuclide concentrations in man's exposure environment, (2) radionuclide intake by exposed individuals per unit concentration in the environment, (3) the dose per unit intake, (4) the number of exposed individuals, and (5) the health risk per unit dose. For the important long-lived radionuclides in high-level waste, uncertainties in most of the different components of a calculation of individual and collective dose per unit release appear to be no more than two or three orders of magnitude; these uncertainties are certainly much less than uncertainties in predicting groundwater transport of radionuclides between a repository and the biosphere. Several limitations in current models for predicting the health risk to man per unit release to the biosphere are discussed

  2. Simulating selenium and nitrogen fate and transport in coupled stream-aquifer systems of irrigated regions

    Science.gov (United States)

    Shultz, Christopher D.; Bailey, Ryan T.; Gates, Timothy K.; Heesemann, Brent E.; Morway, Eric D.

    2018-01-01

    Elevated levels of selenium (Se) in aqueous environments can harm aquatic life and endanger livestock and human health. Although Se occurs naturally in the rocks and soils of many alluvial aquifers, mining and agricultural activities can increase its rate of mobilization and transport to surface waters. Attention is given here to regions where nonpoint source return flows from irrigated lands carry pollutant loads to aquifers and streams, contributing to concentrations that violate regulatory and performance standards. Of particular concern is the heightened level and mobilization of Se influenced by nitrate (NO3), a harmful pollutant in its own right. We present a numerical model that simulates the reactive transport of Se and nitrogen (N) species in a coupled groundwater-surface water system. Building upon a conceptual model that incorporates the major processes affecting Se and NO3 transport in an irrigated watershed, the model links the finite-difference models MODFLOW, UZF-RT3D, and OTIS, to simulate flow and reactive transport of multiple chemical species in both the aquifer and a stream network, with mass exchange between the two. The capability of the new model is showcased by calibration, testing, and application to a 500 km2 region in Colorado’s Lower Arkansas River Valley using a rich data set gathered over a 10-yr period. Simulation of spatial and temporal distributions of Se concentration reveals conditions that exceed standards in groundwater for approximately 20% of the area. For the Arkansas River, standards are exceeded by 290%–450%. Simulation indicates that river concentrations of NO3 alone are near the current interim standard for the total of all dissolved N species. These results indicate the need for future use of the developed model to investigate the prospects for land and water best management practices to decrease pollutant levels.

  3. Simulating selenium and nitrogen fate and transport in coupled stream-aquifer systems of irrigated regions

    Science.gov (United States)

    Shultz, Christopher D.; Bailey, Ryan T.; Gates, Timothy K.; Heesemann, Brent E.; Morway, Eric D.

    2018-05-01

    Elevated levels of selenium (Se) in aqueous environments can harm aquatic life and endanger livestock and human health. Although Se occurs naturally in the rocks and soils of many alluvial aquifers, mining and agricultural activities can increase its rate of mobilization and transport to surface waters. Attention is given here to regions where nonpoint source return flows from irrigated lands carry pollutant loads to aquifers and streams, contributing to concentrations that violate regulatory and performance standards. Of particular concern is the heightened level and mobilization of Se influenced by nitrate (NO3), a harmful pollutant in its own right. We present a numerical model that simulates the reactive transport of Se and nitrogen (N) species in a coupled groundwater-surface water system. Building upon a conceptual model that incorporates the major processes affecting Se and NO3 transport in an irrigated watershed, the model links the finite-difference models MODFLOW, UZF-RT3D, and OTIS, to simulate flow and reactive transport of multiple chemical species in both the aquifer and a stream network, with mass exchange between the two. The capability of the new model is showcased by calibration, testing, and application to a 500 km2 region in Colorado's Lower Arkansas River Valley using a rich data set gathered over a 10-yr period. Simulation of spatial and temporal distributions of Se concentration reveals conditions that exceed standards in groundwater for approximately 20% of the area. For the Arkansas River, standards are exceeded by 290%-450%. Simulation indicates that river concentrations of NO3 alone are near the current interim standard for the total of all dissolved N species. These results indicate the need for future use of the developed model to investigate the prospects for land and water best management practices to decrease pollutant levels.

  4. Design and testing of a process-based groundwater vulnerability assessment (P-GWAVA) system for predicting concentrations of agrichemicals in groundwater across the United States

    Science.gov (United States)

    Barbash, Jack E; Voss, Frank D.

    2016-03-29

    Efforts to assess the likelihood of groundwater contamination from surface-derived compounds have spanned more than three decades. Relatively few of these assessments, however, have involved the use of process-based simulations of contaminant transport and fate in the subsurface, or compared the predictions from such models with measured data—especially over regional to national scales. To address this need, a process-based groundwater vulnerability assessment (P-GWAVA) system was constructed to use transport-and-fate simulations to predict the concentration of any surface-derived compound at a specified depth in the vadose zone anywhere in the conterminous United States. The system was then used to simulate the concentrations of selected agrichemicals in the vadose zone beneath agricultural areas in multiple locations across the conterminous United States. The simulated concentrations were compared with measured concentrations of the compounds detected in shallow groundwater (that is, groundwater drawn from within a depth of 6.3 ± 0.5 meters [mean ± 95 percent confidence interval] below the water table) in more than 1,400 locations across the United States. The results from these comparisons were used to select the simulation approaches that led to the closest agreement between the simulated and the measured concentrations.The P-GWAVA system uses computer simulations that account for a broader range of the hydrologic, physical, biological and chemical phenomena known to control the transport and fate of solutes in the subsurface than has been accounted for by any other vulnerability assessment over regional to national scales. Such phenomena include preferential transport and the influences of temperature, soil properties, and depth on the partitioning, transport, and transformation of pesticides in the subsurface. Published methods and detailed soil property data are used to estimate a wide range of model input parameters for each site, including surface

  5. Testing of a benchscale Reverse Osmosis/Coupled Transport system for treating contaminated groundwater

    International Nuclear Information System (INIS)

    Hodgson, K.M.; Lunsford, T.R.; Panjabi, G.

    1994-01-01

    The Reverse Osmosis/Coupled Transport process is a innovative means of removing radionuclides from contaminated groundwater at the Hanford Site. Specifically, groundwater in the 200 West Area of the Hanford Site has been contaminated with uranium, technetium, and nitrate. Investigations are proceeding to determine the most cost effective method to remove these contaminants. The process described in this paper combines three different membrane technologies (reverse osmosis, coupled transport, and nanofiltration to purify the groundwater while extracting and concentrating uranium, technetium, and nitrate into separate solutions. This separation allows for the future use of the radionuclides, if needed, and reduces the amount of waste that will need to be disposed of. This process has the potential to concentrate the contaminants into solutions with volumes in a ratio of 1/10,000 of the feed volume. This compares to traditional volume reductions of 10 to 100 for ion exchange and stand-alone reverse osmosis. The successful demonstration of this technology could result in significant savings in the overall cost of decontaminating the groundwater

  6. Modeling of Groundwater Flow and Radionuclide Transport at the Climax Mine sub-CAU, Nevada Test Site

    International Nuclear Information System (INIS)

    K. Pohlmann; M. Ye; D. Reeves; M. Zavarin; D. Decker; J. Chapman

    2007-01-01

    subsequent modeling studies at Climax. The objectives of the Climax Mine sub-CAU work are to (1) provide simulated heads and groundwater flows for the northern boundaries of the Yucca Flat-Climax Mine CAU model, while incorporating alternative conceptualizations of the hydrogeologic system with their associated uncertainty, and (2) provide radionuclide fluxes from the three tests in the Climax stock using modeling techniques that account for groundwater flow in fractured granite. Meeting these two objectives required two different model scales. The northern boundary groundwater fluxes were addressed using the Death Valley Regional Flow System (DVRFS) model (Belcher, 2004) developed by the U.S. Geological Survey as a modeling framework, with refined hydrostratigraphy in a zone north of Yucca Flat and including Climax stock. Radionuclide transport was simulated using a separate model confined to the granite stock itself, but linked to regional groundwater flow through boundary conditions and calibration targets

  7. Modeling of Groundwater Flow and Radionuclide Transport at the Climax Mine sub-CAU, Nevada Test Site

    Energy Technology Data Exchange (ETDEWEB)

    K. Pohlmann; M. Ye; D. Reeves; M. Zavarin; D. Decker; J. Chapman

    2007-09-28

    subsequent modeling studies at Climax. The objectives of the Climax Mine sub-CAU work are to (1) provide simulated heads and groundwater flows for the northern boundaries of the Yucca Flat-Climax Mine CAU model, while incorporating alternative conceptualizations of the hydrogeologic system with their associated uncertainty, and (2) provide radionuclide fluxes from the three tests in the Climax stock using modeling techniques that account for groundwater flow in fractured granite. Meeting these two objectives required two different model scales. The northern boundary groundwater fluxes were addressed using the Death Valley Regional Flow System (DVRFS) model (Belcher, 2004) developed by the U.S. Geological Survey as a modeling framework, with refined hydrostratigraphy in a zone north of Yucca Flat and including Climax stock. Radionuclide transport was simulated using a separate model confined to the granite stock itself, but linked to regional groundwater flow through boundary conditions and calibration targets.

  8. Simultaneous identification of unknown groundwater pollution sources and estimation of aquifer parameters

    Science.gov (United States)

    Datta, Bithin; Chakrabarty, Dibakar; Dhar, Anirban

    2009-09-01

    Pollution source identification is a common problem encountered frequently. In absence of prior information about flow and transport parameters, the performance of source identification models depends on the accuracy in estimation of these parameters. A methodology is developed for simultaneous pollution source identification and parameter estimation in groundwater systems. The groundwater flow and transport simulator is linked to the nonlinear optimization model as an external module. The simulator defines the flow and transport processes, and serves as a binding equality constraint. The Jacobian matrix which determines the search direction in the nonlinear optimization model links the groundwater flow-transport simulator and the optimization method. Performance of the proposed methodology using spatiotemporal hydraulic head values and pollutant concentration measurements is evaluated by solving illustrative problems. Two different decision model formulations are developed. The computational efficiency of these models is compared using two nonlinear optimization algorithms. The proposed methodology addresses some of the computational limitations of using the embedded optimization technique which embeds the discretized flow and transport equations as equality constraints for optimization. Solution results obtained are also found to be better than those obtained using the embedded optimization technique. The performance evaluations reported here demonstrate the potential applicability of the developed methodology for a fairly large aquifer study area with multiple unknown pollution sources.

  9. Combining groundwater quality analysis and a numerical flow simulation for spatially establishing utilization strategies for groundwater and surface water in the Pingtung Plain

    Science.gov (United States)

    Jang, Cheng-Shin; Chen, Ching-Fang; Liang, Ching-Ping; Chen, Jui-Sheng

    2016-02-01

    Overexploitation of groundwater is a common problem in the Pingtung Plain area of Taiwan, resulting in substantial drawdown of groundwater levels as well as the occurrence of severe seawater intrusion and land subsidence. Measures need to be taken to preserve these valuable groundwater resources. This study seeks to spatially determine the most suitable locations for the use of surface water on this plain instead of extracting groundwater for drinking, irrigation, and aquaculture purposes based on information obtained by combining groundwater quality analysis and a numerical flow simulation assuming the planning of manmade lakes and reservoirs to the increase of water supply. The multivariate indicator kriging method is first used to estimate occurrence probabilities, and to rank townships as suitable or unsuitable for groundwater utilization according to water quality standards for drinking, irrigation, and aquaculture. A numerical model of groundwater flow (MODFLOW) is adopted to quantify the recovery of groundwater levels in townships after model calibration when groundwater for drinking and agricultural demands has been replaced by surface water. Finally, townships with poor groundwater quality and significant increases in groundwater levels in the Pingtung Plain are prioritized for the groundwater conservation planning based on the combined assessment of groundwater quality and quantity. The results of this study indicate that the integration of groundwater quality analysis and the numerical flow simulation is capable of establishing sound strategies for joint groundwater and surface water use. Six southeastern townships are found to be suitable locations for replacing groundwater with surface water from manmade lakes or reservoirs to meet drinking, irrigation, and aquaculture demands.

  10. Simulating the effects of a beaver dam on regional groundwater flow through a wetland

    Directory of Open Access Journals (Sweden)

    Kathleen Feiner

    2015-09-01

    New hydrological insights for the region: The construction of a beaver dam resulted in minimal changes to regional groundwater flow paths at this site, which is attributed to a clay unit underlying the peat, disconnecting this wetland from regional groundwater flow. However, groundwater discharge from the wetland pond increased by 90%. Simulating a scenario with the numerical model in which the wetland is connected to regional groundwater flow results in a much larger impact on flow paths. In the absence of the clay layer, the simulated construction of a beaver dam causes a 70% increase in groundwater discharge from the wetland pond and increases the surface area of both the capture zone and the discharge zone by 30% and 80%, respectively.

  11. Coupling and Testing the Fate and Transport of Heavy Metals and Other Ionic Species in a Groundwater Setting at Oak Ridge, TN - 13498

    Energy Technology Data Exchange (ETDEWEB)

    Noosai, Nantaporn; Fuentes, Hector R. [CEE Florida International University, Miami, FL 33174 (United States)

    2013-07-01

    Historical data show that heavy metals (including mercury) were released from Y -12 National Security Complex (NSC) at Oak Ridge, Tennessee, to the surrounding environments during its operation in 1950's. Studies have also shown that metals accumulated in the soil, rock, and groundwater, and are, at the present time, sources of contamination to nearby rivers and creeks (e.g., East Fork Poplar Creek, Bear Creek). For instance, mercury (Hg), zinc (Zn), cadmium (Cd) and lead (Pb) have been found and reported on the site groundwater. The groundwater type at the site is Ca-Mg-HCO{sub 3}. This paper presents a modeling application of PHREEQC, a model that simulates geochemical processes and couples them to flow and transport settings. The objective was to assess the capability of PHREEQC to simulate the transport of ionic species in groundwater at Oak Ridge, Tennessee; data were available from core holes and monitoring wells over a 736-m distance, within 60-300 m depths. First, predictions of the transport of major ionic species (i.e., Ca{sup 2+} and Mg{sup 2+}) in the water were made between monitoring wells and for GW-131. Second, the model was used to assess hypotheses under two scenarios of transport for Zn, Cd, Pb and Hg, in Ca-Mg-HCO{sub 3} water, as influenced by the following solid-liquid interactions: a) the role of ion exchange and b) the role of both ion exchange and sorption, the latter via surface complexation with Fe(OH){sub 3}. The transport scenario with ion exchange suggests that significant ion exchange is expected to occur for Zn, Cd and Pb concentrations, with no significant impact on Hg, within the first 100 m. Predictions match the expected values of the exchange coefficients relative to Ca{sup 2+} and Mg{sup 2+} (e.g., K{sub Ca/Zn} = K{sub Ca/Cd} > K{sub Ca/Pb} > K{sub Ca/Hg}). The scenario with both ion exchange and sorption does affect the concentrations of Zn and Cd to a small extent within the first 100 m, but does more meaningfully reduce

  12. A Monte Carlo simulation method for assessing biotransformation effects on groundwater fuel hydrocarbon plume lengths

    International Nuclear Information System (INIS)

    McNab, W.W. Jr.

    2000-01-01

    Biotransformation of dissolved groundwater hydrocarbon plumes emanating from leaking underground fuel tanks should, in principle, result in plume length stabilization over relatively short distances, thus diminishing the environmental risk. However, because the behavior of hydrocarbon plumes is usually poorly constrained at most leaking underground fuel tank sites in terms of release history, groundwater velocity, dispersion, as well as the biotransformation rate, demonstrating such a limitation in plume length is problematic. Biotransformation signatures in the aquifer geochemistry, most notably elevated bicarbonate, may offer a means of constraining the relationship between plume length and the mean biotransformation rate. In this study, modeled plume lengths and spatial bicarbonate differences among a population of synthetic hydrocarbon plumes, generated through Monte Carlo simulation of an analytical solute transport model, are compared to field observations from six underground storage tank (UST) sites at military bases in California. Simulation results indicate that the relationship between plume length and the distribution of bicarbonate is best explained by biotransformation rates that are consistent with ranges commonly reported in the literature. This finding suggests that bicarbonate can indeed provide an independent means for evaluating limitations in hydrocarbon plume length resulting from biotransformation. (Author)

  13. Groundwater flow simulation on local scale. Setting boundary conditions of groundwater flow simulation on site scale model in the step 4

    International Nuclear Information System (INIS)

    Onoe, Hironori; Saegusa, Hiromitsu; Ohyama, Takuya

    2007-03-01

    Japan Atomic Energy Agency has been conducting a wide range of geoscientific research in order to build a foundation for multidisciplinary studies of the deep geological environment as a basis of research and development for geological disposal of nuclear wastes. Ongoing geoscientific research programs include the Regional Hydrogeological Study (RHS) project and Mizunami Underground Research Laboratory (MIU) project in the Tono region, Gifu Prefecture. The main goal of these projects is to establish comprehensive techniques for investigation, analysis, and assessment of the deep geological at several spatial scales. The RHS project is a Local scale study for understanding the groundwater flow system from the recharge area to the discharge area. The Surface-based Investigation Phase of the MIU project is a Site scale study for understanding the deep geological environment immediately surrounding the MIU construction site using a multiphase, iterative approach. In this study, the hydrogeological modeling and groundwater flow simulation on Local scale were carried out in order to set boundary conditions of the Site scale model based on the data obtained from surface-based investigations in the Step4 in Site scale of the MIU project. As a result of the study, boundary conditions for groundwater flow simulation on the Site scale model of the Step4 could be obtained. (author)

  14. Evaluation of the groundwater flow model for southern Utah and Goshen Valleys, Utah, updated to conditions through 2011, with new projections and groundwater management simulations

    Science.gov (United States)

    Brooks, Lynette E.

    2013-01-01

    The U.S. Geological Survey (USGS), in cooperation with the Southern Utah Valley Municipal Water Association, updated an existing USGS model of southern Utah and Goshen Valleys for hydrologic and climatic conditions from 1991 to 2011 and used the model for projection and groundwater management simulations. All model files used in the transient model were updated to be compatible with MODFLOW-2005 and with the additional stress periods. The well and recharge files had the most extensive changes. Discharge to pumping wells in southern Utah and Goshen Valleys was estimated and simulated on an annual basis from 1991 to 2011. Recharge estimates for 1991 to 2011 were included in the updated model by using precipitation, streamflow, canal diversions, and irrigation groundwater withdrawals for each year. The model was evaluated to determine how well it simulates groundwater conditions during recent increased withdrawals and drought, and to determine if the model is adequate for use in future planning. In southern Utah Valley, the magnitude and direction of annual water-level fluctuation simulated by the updated model reasonably match measured water-level changes, but they do not simulate as much decline as was measured in some locations from 2000 to 2002. Both the rapid increase in groundwater withdrawals and the total groundwater withdrawals in southern Utah Valley during this period exceed the variations and magnitudes simulated during the 1949 to 1990 calibration period. It is possible that hydraulic properties may be locally incorrect or that changes, such as land use or irrigation diversions, occurred that are not simulated. In the northern part of Goshen Valley, simulated water-level changes reasonably match measured changes. Farther south, however, simulated declines are much less than measured declines. Land-use changes indicate that groundwater withdrawals in Goshen Valley are possibly greater than estimated and simulated. It is also possible that irrigation

  15. Application of a modified conceptual rainfall-runoff model to simulation of groundwater level in an undefined watershed.

    Science.gov (United States)

    Hong, Nian; Hama, Takehide; Suenaga, Yuichi; Aqili, Sayed Waliullah; Huang, Xiaowu; Wei, Qiaoyan; Kawagoshi, Yasunori

    2016-01-15

    Groundwater level simulation models can help ensure the proper management and use of urban and rural water supply. In this paper, we propose a groundwater level tank model (GLTM) based on a conceptual rainfall-runoff model (tank model) to simulate fluctuations in groundwater level. The variables used in the simulations consist of daily rainfall and daily groundwater level, which were recorded between April 2011 and March 2015 at two representative observation wells in Kumamoto City, Japan. We determined the best-fit model parameters by root-mean-square error through use of the Shuffled Complex Evolution-University of Arizona algorithm on a simulated data set. Calibration and validation results were evaluated by their coefficients of determination, Nash-Sutcliffe efficiency coefficients, and root-mean-square error values. The GLTM provided accurate results in both the calibration and validation of fluctuations in groundwater level. The split sample test results indicate a good reliability. These results indicate that this model can provide a simple approach to the accurate simulation of groundwater levels. Copyright © 2015 Elsevier B.V. All rights reserved.

  16. Groundwater Flow and Radionuclide Transport in Fault Zones in Granitic Rock

    International Nuclear Information System (INIS)

    Geier, Joel Edward

    2004-12-01

    Fault zones are potential paths for release of radioactive nuclides from radioactive-waste repositories in granitic rock. This research considers detailed maps of en echelon fault zones at two sites in southern Sweden, as a basis for analyses of how their internal geometry can influence groundwater flow and transport of radioactive nuclides. Fracture intensity within these zones is anisotropic and correlated over scales of several meters along strike, corresponding to the length and spacing of the en echelon steps. Flow modeling indicates these properties lead to correlation of zone transmissivity over similar scales. Intensity of fractures in the damage zone adjoining en echelon segments decreases exponentially with distance. These fractures are linked to en echelon segments as a hierarchical pattern of branches. Echelon steps also show a hierarchical internal structure. These traits suggest a fractal increase in the amount of pore volume that solute can access by diffusive mass transfer, with increasing distance from en echelon segments. Consequences may include tailing of solute breakthrough curves, similar to that observed in underground tracer experiments at one of the mapping sites. The implications of echelon-zone architecture are evaluated by numerical simulation of flow and solute transport in 2-D network models, including deterministic models based directly on mapping data, and a statistical model. The simulations account for advection, diffusion-controlled mixing across streamlines within fractures and at intersections, and diffusion into both stagnant branch fractures and macroscopically unfractured matrix. The simulations show that secondary fractures contribute to retardation of solute, although their net effect is sensitive to assumptions regarding heterogeneity of transmissivity and transport aperture. Detailed results provide insight into the function of secondary fractures as an immobile domain affecting mass transfer on time scales relevant to

  17. Phast4Windows: a 3D graphical user interface for the reactive-transport simulator PHAST.

    Science.gov (United States)

    Charlton, Scott R; Parkhurst, David L

    2013-01-01

    Phast4Windows is a Windows® program for developing and running groundwater-flow and reactive-transport models with the PHAST simulator. This graphical user interface allows definition of grid-independent spatial distributions of model properties-the porous media properties, the initial head and chemistry conditions, boundary conditions, and locations of wells, rivers, drains, and accounting zones-and other parameters necessary for a simulation. Spatial data can be defined without reference to a grid by drawing, by point-by-point definitions, or by importing files, including ArcInfo® shape and raster files. All definitions can be inspected, edited, deleted, moved, copied, and switched from hidden to visible through the data tree of the interface. Model features are visualized in the main panel of the interface, so that it is possible to zoom, pan, and rotate features in three dimensions (3D). PHAST simulates single phase, constant density, saturated groundwater flow under confined or unconfined conditions. Reactions among multiple solutes include mineral equilibria, cation exchange, surface complexation, solid solutions, and general kinetic reactions. The interface can be used to develop and run simple or complex models, and is ideal for use in the classroom, for analysis of laboratory column experiments, and for development of field-scale simulations of geochemical processes and contaminant transport. Published 2012. This article is a U.S. Government work and is in the public domain in the USA.

  18. Groundwater nitrate concentration evolution under climate change and agricultural adaptation scenarios: Prince Edward Island, Canada

    Science.gov (United States)

    Paradis, Daniel; Vigneault, Harold; Lefebvre, René; Savard, Martine M.; Ballard, Jean-Marc; Qian, Budong

    2016-03-01

    Nitrate (N-NO3) concentration in groundwater, the sole source of potable water in Prince Edward Island (PEI, Canada), currently exceeds the 10 mg L-1 (N-NO3) health threshold for drinking water in 6 % of domestic wells. Increasing climatic and socio-economic pressures on PEI agriculture may further deteriorate groundwater quality. This study assesses how groundwater nitrate concentration could evolve due to the forecasted climate change and its related potential changes in agricultural practices. For this purpose, a tridimensional numerical groundwater flow and mass transport model was developed for the aquifer system of the entire Island (5660 km2). A number of different groundwater flow and mass transport simulations were made to evaluate the potential impact of the projected climate change and agricultural adaptation. According to the simulations for year 2050, N-NO3 concentration would increase due to two main causes: (1) the progressive attainment of steady-state conditions related to present-day nitrogen loadings, and (2) the increase in nitrogen loadings due to changes in agricultural practices provoked by future climatic conditions. The combined effects of equilibration with loadings, climate and agricultural adaptation would lead to a 25 to 32 % increase in N-NO3 concentration over the Island aquifer system. The change in groundwater recharge regime induced by climate change (with current agricultural practices) would only contribute 0 to 6 % of that increase for the various climate scenarios. Moreover, simulated trends in groundwater N-NO3 concentration suggest that an increased number of domestic wells (more than doubling) would exceed the nitrate drinking water criteria. This study underlines the need to develop and apply better agricultural management practices to ensure sustainability of long-term groundwater resources. The simulations also show that observable benefits from positive changes in agricultural practices would be delayed in time due to

  19. A Graphical-User Interface for the U. S. Geological Survey's SUTRA Code using Argus ONE (for simulation of variable-density saturated-unsaturated ground-water flow with solute or energy transport)

    Science.gov (United States)

    Voss, Clifford I.; Boldt, David; Shapiro, Allen M.

    1997-01-01

    This report describes a Graphical-User Interface (GUI) for SUTRA, the U.S. Geological Survey (USGS) model for saturated-unsaturated variable-fluid-density ground-water flow with solute or energy transport,which combines a USGS-developed code that interfaces SUTRA with Argus ONE, a commercial software product developed by Argus Interware. This product, known as Argus Open Numerical Environments (Argus ONETM), is a programmable system with geographic-information-system-like (GIS-like) functionality that includes automated gridding and meshing capabilities for linking geospatial information with finite-difference and finite-element numerical model discretizations. The GUI for SUTRA is based on a public-domain Plug-In Extension (PIE) to Argus ONE that automates the use of ArgusONE to: automatically create the appropriate geospatial information coverages (information layers) for SUTRA, provide menus and dialogs for inputting geospatial information and simulation control parameters for SUTRA, and allow visualization of SUTRA simulation results. Following simulation control data and geospatial data input bythe user through the GUI, ArgusONE creates text files in a format required for normal input to SUTRA,and SUTRA can be executed within the Argus ONE environment. Then, hydraulic head, pressure, solute concentration, temperature, saturation and velocity results from the SUTRA simulation may be visualized. Although the GUI for SUTRA discussed in this report provides all of the graphical pre- and post-processor functions required for running SUTRA, it is also possible for advanced users to apply programmable features within Argus ONE to modify the GUI to meet the unique demands of particular ground-water modeling projects.

  20. Simulation of the Groundwater-Flow System in Pierce, Polk, and St. Croix Counties, Wisconsin

    Science.gov (United States)

    Juckem, Paul F.

    2009-01-01

    Groundwater is the sole source of residential water supply in Pierce, Polk, and St. Croix Counties, Wisconsin. A regional three-dimensional groundwater-flow model and three associated demonstration inset models were developed to simulate the groundwater-flow systems in the three-county area. The models were developed by the U.S. Geological Survey in cooperation with the three county governments. The objectives of the regional model of Pierce, Polk, and St. Croix Counties were to improve understanding of the groundwaterflow system and to develop a tool suitable for evaluating the effects of potential water-management programs. The regional groundwater-flow model described in this report simulates the major hydrogeologic features of the modeled area, including bedrock and surficial aquifers, groundwater/surface-water interactions, and groundwater withdrawals from high-capacity wells. Results from the regional model indicate that about 82 percent of groundwater in the three counties is from recharge within the counties; 15 percent is from surface-water sources, consisting primarily of recirculated groundwater seepage in areas with abrupt surface-water-level changes, such as near waterfalls, dams, and the downgradient side of reservoirs and lakes; and 4 percent is from inflow across the county boundaries. Groundwater flow out of the counties is to streams (85 percent), outflow across county boundaries (14 percent), and pumping wells (1 percent). These results demonstrate that the primary source of groundwater withdrawn by pumping wells is water that recharges within the counties and would otherwise discharge to local streams and lakes. Under current conditions, the St. Croix and Mississippi Rivers are groundwater discharge locations (gaining reaches) and appear to function as 'fully penetrating' hydraulic boundaries such that groundwater does not cross between Wisconsin and Minnesota beneath them. Being hydraulic boundaries, however, they can change in response to

  1. Residence times of groundwater and nitrate transport in coastal aquifer systems: Daweijia area, northeastern China

    International Nuclear Information System (INIS)

    Han, Dongmei; Cao, Guoliang; McCallum, James; Song, Xianfang

    2015-01-01

    Groundwater within the coastal aquifer systems of the Daweijia area in northeastern China is characterized by a large of variations (33–521 mg/L) in NO_3"− concentrations. Elevated nitrate concentrations, in addition to seawater intrusion in the Daweijia well field, both attributable to anthropogenic activities, may impact future water-management practices. Chemical and stable isotopic (δ"1"8O, δ"2H) analysis, "3H and CFCs methods were applied to provide a better understanding of the relationship between the distribution of groundwater mean residence time (MRT) and nitrate transport, and to identify sources of nitrate concentrations in the complex coastal aquifer systems. There is a relatively narrow range of isotopic composition (ranging from − 8.5 to − 7.0‰) in most groundwater. Generally higher tritium contents observed in the wet season relative to the dry season may result from rapid groundwater circulation in response to the rainfall through the preferential flow paths. In the well field, the relatively increased nitrate concentrations of groundwater, accompanied by the higher tritium contents in the wet season, indicate the nitrate pollution can be attributed to domestic wastes. The binary exponential and piston-flow mixing model (BEP) yielded feasible age distributions based on the conceptual model. The good inverse relationship between groundwater MRTs (92–467 years) and the NO_3"− concentrations in the shallow Quaternary aquifers indicates that elevated nitrate concentrations are attributable to more recent recharge for shallow groundwater. However, there is no significant relationship between the MRTs (8–411 years) and the NO_3"− concentrations existing in the carbonate aquifer system, due to the complex hydrogeological conditions, groundwater age distributions and the range of contaminant source areas. Nitrate in the groundwater system without denitrification effects could accumulate and be transported for tens of years, through the

  2. Residence times of groundwater and nitrate transport in coastal aquifer systems: Daweijia area, northeastern China

    Energy Technology Data Exchange (ETDEWEB)

    Han, Dongmei [Key Laboratory of Water Cycle & Related Land Surface Processes, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101 (China); National Centre for Groundwater Research and Training, Flinders University, GPO Box 2100, Adelaide, SA 5001 (Australia); Cao, Guoliang [National Centre for Groundwater Research and Training, Flinders University, GPO Box 2100, Adelaide, SA 5001 (Australia); Center for Water Research, College of Engineering, Peking University, Beijing 100871 (China); McCallum, James [National Centre for Groundwater Research and Training, Flinders University, GPO Box 2100, Adelaide, SA 5001 (Australia); School of the Environment, Flinders University, GPO Box 2100, Adelaide, SA 5001 (Australia); Song, Xianfang [Key Laboratory of Water Cycle & Related Land Surface Processes, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101 (China)

    2015-12-15

    Groundwater within the coastal aquifer systems of the Daweijia area in northeastern China is characterized by a large of variations (33–521 mg/L) in NO{sub 3}{sup −} concentrations. Elevated nitrate concentrations, in addition to seawater intrusion in the Daweijia well field, both attributable to anthropogenic activities, may impact future water-management practices. Chemical and stable isotopic (δ{sup 18}O, δ{sup 2}H) analysis, {sup 3}H and CFCs methods were applied to provide a better understanding of the relationship between the distribution of groundwater mean residence time (MRT) and nitrate transport, and to identify sources of nitrate concentrations in the complex coastal aquifer systems. There is a relatively narrow range of isotopic composition (ranging from − 8.5 to − 7.0‰) in most groundwater. Generally higher tritium contents observed in the wet season relative to the dry season may result from rapid groundwater circulation in response to the rainfall through the preferential flow paths. In the well field, the relatively increased nitrate concentrations of groundwater, accompanied by the higher tritium contents in the wet season, indicate the nitrate pollution can be attributed to domestic wastes. The binary exponential and piston-flow mixing model (BEP) yielded feasible age distributions based on the conceptual model. The good inverse relationship between groundwater MRTs (92–467 years) and the NO{sub 3}{sup −} concentrations in the shallow Quaternary aquifers indicates that elevated nitrate concentrations are attributable to more recent recharge for shallow groundwater. However, there is no significant relationship between the MRTs (8–411 years) and the NO{sub 3}{sup −} concentrations existing in the carbonate aquifer system, due to the complex hydrogeological conditions, groundwater age distributions and the range of contaminant source areas. Nitrate in the groundwater system without denitrification effects could accumulate and be

  3. Simulation of groundwater and surface-water flow in the upper Deschutes Basin, Oregon

    Science.gov (United States)

    Gannett, Marshall W.; Lite, Kenneth E.; Risley, John C.; Pischel, Esther M.; La Marche, Jonathan L.

    2017-10-20

    This report describes a hydrologic model for the upper Deschutes Basin in central Oregon developed using the U.S. Geological Survey (USGS) integrated Groundwater and Surface-Water Flow model (GSFLOW). The upper Deschutes Basin, which drains much of the eastern side of the Cascade Range in Oregon, is underlain by large areas of permeable volcanic rock. That permeability, in combination with the large annual precipitation at high elevations, results in a substantial regional aquifer system and a stream system that is heavily groundwater dominated.The upper Deschutes Basin is also an area of expanding population and increasing water demand for public supply and agriculture. Surface water was largely developed for agricultural use by the mid-20th century, and is closed to additional appropriations. Consequently, water users look to groundwater to satisfy the growing demand. The well‑documented connection between groundwater and the stream system, and the institutional and legal restrictions on streamflow depletion by wells, resulted in the Oregon Water Resources Department (OWRD) instituting a process whereby additional groundwater pumping can be permitted only if the effects to streams are mitigated, for example, by reducing permitted surface-water diversions. Implementing such a program requires understanding of the spatial and temporal distribution of effects to streams from groundwater pumping. A groundwater model developed in the early 2000s by the USGS and OWRD has been used to provide insights into the distribution of streamflow depletion by wells, but lacks spatial resolution in sensitive headwaters and spring areas.The integrated model developed for this project, based largely on the earlier model, has a much finer grid spacing allowing resolution of sensitive headwater streams and important spring areas, and simulates a more complete set of surface processes as well as runoff and groundwater flow. In addition, the integrated model includes improved

  4. Simulation of groundwater flow pathlines and freshwater/saltwater transition zone movement, Manhasset Neck, Nassau County, New York

    Science.gov (United States)

    Misut, Paul; Aphale, Omkar

    2014-01-01

    A density-dependent groundwater flow and solute transport model of Manhasset Neck, Long Island, New York, was used to analyze (1) the effects of seasonal stress on the position of the freshwater/saltwater transition zone and (2) groundwater flowpaths. The following were used in the simulation: 182 transient stress periods, representing the historical record from 1920 to 2011, and 44 transient stress periods, representing future hypothetical conditions from 2011 to 2030. Simulated water-level and salinity (chloride concentration) values are compared with values from a previously developed two-stress-period (1905–1944 and 1945–2005) model. The 182-stress-period model produced salinity (chloride concentration) values that more accurately matched the observed salinity (chloride concentration) values in response to hydrologic stress than did the two-stress-period model, and salinity ranged from zero to about 3 parts per thousand (equivalent to zero to 1,660 milligrams per liter chloride). The 182-stress-period model produced improved calibration statistics of water-level measurements made throughout the study area than did the two-stress-period model, reducing the Lloyd aquifer root mean square error from 7.0 to 5.2 feet. Decreasing horizontal and vertical hydraulic conductivities (fixed anisotropy ratio) of the Lloyd and North Shore aquifers by 20 percent resulted in nearly doubling the simulated salinity(chloride concentration) increase at Port Washington observation well N12508. Groundwater flowpath analysis was completed for 24 production wells to delineate water source areas. The freshwater/saltwater transition zone moved toward and(or) away from wells during future hypothetical scenarios.

  5. Calculation of three-dimensional groundwater transport using second-order moments

    International Nuclear Information System (INIS)

    Pepper, D.W.; Stephenson, D.E.

    1987-01-01

    Groundwater transport of contaminants from the F-Area seepage basin at the Savannah River Plant (SRP) was calculated using a three-dimensional, second-order moment technique. The numerical method calculates the zero, first, and second moment distributions of concentration within a cell volume. By summing the moments over the entire solution domain, and using a Lagrangian advection scheme, concentrations are transported without numerical dispersion errors. Velocities obtained from field tests are extrapolated and interpolated to all nodal points; a variational analysis is performed over the three-dimensional velocity field to ensure mass consistency. Transport predictions are calculated out to 12,000 days. 28 refs., 9 figs

  6. Modeling the migration of radioactive contaminants in groundwater of in situ leaching uranium mine

    International Nuclear Information System (INIS)

    Li Chunguang; Tai Kaixuan

    2011-01-01

    The radioactive contamination of groundwater from in situ leaching (ISL) of uranium mining is a widespread environmental problem. This paper analyzed the monitor results of groundwater contaminations for a in situ leaching uranium mine. A dynamic model of contaminants transport in groundwater in ISL well field was established. The processes and mechanisms of contaminant transport in groundwater were simulated numerically for a ISL well field. A small quantity of U and SO 4 2- migrate to outside of well field during ISL production stage. But the migration velocity and distance of contaminations is small, and the concentration is low. Contaminants migrate as anomalistic tooth-shape. The migration trend of U and SO 4 2- is consistent. Numerical modeling can provide an effective approach to analyse the transport mechanism, and forecast and control the migration of contaminants in groundwater in ISL well field. (authors)

  7. Investigations of groundwater system and simulation of regional groundwater flow for North Penn Area 7 Superfund site, Montgomery County, Pennsylvania

    Science.gov (United States)

    Senior, Lisa A.; Goode, Daniel J.

    2013-01-01

    Groundwater in the vicinity of several industrial facilities in Upper Gwynedd Township and vicinity, Montgomery County, in southeast Pennsylvania has been shown to be contaminated with volatile organic compounds (VOCs), the most common of which is the solvent trichloroethylene (TCE). The 2-square-mile area was placed on the National Priorities List as the North Penn Area 7 Superfund site by the U.S. Environmental Protection Agency (USEPA) in 1989. The U.S. Geological Survey (USGS) conducted geophysical logging, aquifer testing, and water-level monitoring, and measured streamflows in and near North Penn Area 7 from fall 2000 through fall 2006 in a technical assistance study for the USEPA to develop an understanding of the hydrogeologic framework in the area as part of the USEPA Remedial Investigation. In addition, the USGS developed a groundwater-flow computer model based on the hydrogeologic framework to simulate regional groundwater flow and to estimate directions of groundwater flow and pathways of groundwater contaminants. The study area is underlain by Triassic- and Jurassic-age sandstones and shales of the Lockatong Formation and Brunswick Group in the Mesozoic Newark Basin. Regionally, these rocks strike northeast and dip to the northwest. The sequence of rocks form a fractured-sedimentary-rock aquifer that acts as a set of confined to partially confined layers of differing permeabilities. Depth to competent bedrock typically is less than 20 ft below land surface. The aquifer layers are recharged locally by precipitation and discharge locally to streams. The general configuration of the potentiometric surface in the aquifer is similar to topography, except in areas affected by pumping. The headwaters of Wissahickon Creek are nearby, and the stream flows southwest, parallel to strike, to bisect North Penn Area 7. Groundwater is pumped in the vicinity of North Penn Area 7 for industrial use, public supply, and residential supply. Results of field investigations

  8. Decadal variations in groundwater quality

    DEFF Research Database (Denmark)

    Jessen, Søren; Postma, Dieke; Thorling, Lærke

    2017-01-01

    Twenty-five years of groundwater quality monitoring in a sandy aquifer beneath agricultural fields showed large temporal and spatial variations in major ion groundwater chemistry, which were linked closely to the nitrate (NO3) content of agricultural recharge. Between 1988 and 2013, the NO3 content...... of water in the oxidized zone of the aquifer nearly halved, following implementation of action plans to reduce N leaching from agriculture. However, due to denitrification by pyrite oxidation in the aquifer, a plume of sulfate-rich water migrates through the aquifer as a legacy of the historical NO3...... loading. Agriculture thus is an important determinant of major ion groundwater chemistry. Temporal and spatial variations in the groundwater quality were simulated using a 2D reactive transport model, which combined effects of the historical NO3 leaching and denitrification, with dispersive mixing...

  9. Groundwater Flow and Transport Model in Cecina Plain (Tuscany, Italy) using GIS processing

    OpenAIRE

    Riccardo Armellini; Elena Baldini; Dario Del Seppia; Fabrizio Franceschini; Natacha Gori; Stefano Menichetti; Stefano Tessitore

    2015-01-01

    This work provides a groundwater flow and transport model of trichlorethylene and tetrachlorethylene contamination in the Cecina’s coastal aquifer. The contamination analysis, with source located in the Poggio Gagliardo area (Montescudaio, Pisa), was necessary to optimize the groundwater monitoring and remediation design. The work was carried out in two phases: • design of a conceptual model of the aquifer using GIS analysis of many stratigraphic, chemical and hydrogeological data, collected ...

  10. Recharge and Lateral Groundwater Flow Boundary Conditions for the Saturated Zone Site-Scale Flow and Transport Model

    Energy Technology Data Exchange (ETDEWEB)

    B. Arnold; T. Corbet

    2001-12-18

    The purpose of the flow boundary conditions analysis is to provide specified-flux boundary conditions for the saturated zone (SZ) site-scale flow and transport model. This analysis is designed to use existing modeling and analysis results as the basis for estimated groundwater flow rates into the SZ site-scale model domain, both as recharge at the upper (water table) boundary and as underflow at the lateral boundaries. The objective is to provide consistency at the boundaries between the SZ site-scale flow model and other groundwater flow models. The scope of this analysis includes extraction of the volumetric groundwater flow rates simulated by the SZ regional-scale flow model to occur at the lateral boundaries of the SZ site-scale flow model and the internal qualification of the regional-scale model for use in this analysis model report (AMR). In addition, the scope includes compilation of information on the recharge boundary condition taken from three sources: (1) distributed recharge as taken from the SZ regional-scale flow model, (2) recharge below the area of the unsaturated zone (UZ) site-scale flow model, and (3) focused recharge along the Fortymile Wash channel.

  11. Simulation of groundwater flow and pumping scenarios for 1900–2050 near Mount Pleasant, South Carolina

    Science.gov (United States)

    Fine, Jason M.; Petkewich, Matthew D.; Campbell, Bruce G.

    2017-10-31

    Groundwater withdrawals from the Upper Cretaceous-age Middendorf aquifer in South Carolina have created a large, regional cone of depression in the potentiometric surface of the Middendorf aquifer in Charleston and Berkeley Counties, South Carolina. Groundwater-level declines of as much as 249 feet have been observed in wells over the past 125 years and are a result of groundwater use for public water supply, irrigation, and private industry. To address the concerns of users of the Middendorf aquifer, the U.S. Geological Survey, in cooperation with Mount Pleasant Waterworks (MPW), recalibrated an existing groundwater-flow model to incorporate additional groundwater-use and water-level data since 2008. This recalibration process consisted of a technique of parameter estimation that uses regularized inversion and employs “pilot points” for spatial hydraulic property characterization. The groundwater-flow system of the Coastal Plain physiographic province of South Carolina and parts of Georgia and North Carolina was simulated using the U.S. Geological Survey finite-difference computer code MODFLOW-2000.After the model recalibration, the following six predictive water-management scenarios were created to simulate potential changes in groundwater flow and groundwater-level conditions in the Mount Pleasant, South Carolina, area: Scenario 1—maximize MPW reverse-osmosis plant capacity by increasing groundwater withdrawals from the Middendorf aquifer from 3.9 million gallons per day (Mgal/d), which was the amount withdrawn in 2015, to 8.58 Mgal/d; Scenario 2—same as Scenario 1, but with the addition of a 0.5 Mgal/d supply well in the Middendorf aquifer near Moncks Corner, South Carolina; Scenario 3—same as Scenario 1, but with the addition of a 1.5 Mgal/d supply well in the Middendorf aquifer near Moncks Corner, South Carolina; Scenario 4—maximize MPW well capacity by increasing withdrawals from the Middendorf aquifer from 3.9 Mgal/d (in 2015) to 10.16 Mgal

  12. Transport and potential attenuation of nitrogen in shallow groundwaters in the lower Rangitikei catchment, New Zealand.

    Science.gov (United States)

    Collins, S; Singh, R; Rivas, A; Palmer, A; Horne, D; Manderson, A; Roygard, J; Matthews, A

    2017-11-01

    Intensive agricultural activities are generally associated with nitrogen leaching from agricultural soils, and this nitrogen has the potential to percolate and contaminate groundwater and surface waters. We assessed surface water and groundwater interactions, and nitrogen leaching and its potential attenuation in shallow groundwater in the lower Rangitikei River catchment (832km 2 ), New Zealand. We combined regional- and local-scale field surveys and experiments, nutrient budget modelling, and hydraulic and geochemical methods, to gain an insight into leaching, transformation and transport of nitrogen via groundwaters to the river in the study area. Concurrent river flow gaugings (in January 2015) and a piezometric map, developed from measured depths to groundwater in 110 bores (in October 2014), suggest groundwater discharges to the Rangitikei River in the upper parts of the study area, while there is groundwater recharge near the coast. The groundwater redox characterisation, based on sampling and analysis of 15 mostly shallow bores (shallow groundwater piezometers (3-6mbgl) using single-well push-pull tests. We found generally low levels (shallow groundwater piezometers (>5mbgl), despite being installed under intensive land uses, such as dairying and cropping. Our in-field push-pull tests showed NO 3 -N reduction at four shallow groundwater piezometers, with the rates of reduction varying from 0.04mgNL -1 h - 1 to 1.57mgNL -1 h - 1 . This highlights the importance of a sound understanding of not only the sources, but also transport and transformation, or fate, of nutrients leached from farms, to mitigate the likely impacts of land use on water quality and ecosystem health in agricultural catchments. Copyright © 2017 Elsevier B.V. All rights reserved.

  13. Arsenic migration to deep groundwater in Bangladesh influenced by adsorption and water demand

    Science.gov (United States)

    Radloff, K. A.; Zheng, Y.; Michael, H. A.; Stute, M.; Bostick, B. C.; Mihajlov, I.; Bounds, M.; Huq, M. R.; Choudhury, I.; Rahman, M. W.; Schlosser, P.; Ahmed, K. M.; van Geen, A.

    2011-11-01

    The consumption of shallow groundwater with elevated concentrations of arsenic is causing widespread disease in many parts of South and Southeast Asia. In the Bengal Basin, a growing reliance on groundwater sourced below 150-m depth--where arsenic concentrations tend to be lower--has reduced exposure. Groundwater flow simulations have suggested that these deep waters are at risk of contamination due to replenishment with high-arsenic groundwater from above, even when deep water pumping is restricted to domestic use. However, these simulations have neglected the influence of sediment adsorption on arsenic migration. Here, we inject arsenic-bearing groundwater into a deep aquifer zone in Bangladesh, and monitor the reduction in arsenic levels over time following stepwise withdrawal of the water. Arsenic concentrations in the injected water declined by 70% after 24h in the deep aquifer zone, owing to adsorption on sediments; concentrations of a co-injected inert tracer remain unchanged. We incorporate the experimentally determined adsorption properties of sands in the deep aquifer zone into a groundwater flow and transport model covering the Bengal Basin. Simulations using present and future scenarios of water-use suggest that arsenic adsorption significantly retards transport, thereby extending the area over which deep groundwater can be used with low risk of arsenic contamination. Risks are considerably lower when deep water is pumped for domestic use alone. Some areas remain vulnerable to arsenic intrusion, however, and we suggest that these be prioritized for monitoring.

  14. Process-based modelling to evaluate simulated groundwater levels and frequencies in a Chalk catchment in south-western England

    Science.gov (United States)

    Brenner, Simon; Coxon, Gemma; Howden, Nicholas J. K.; Freer, Jim; Hartmann, Andreas

    2018-02-01

    Chalk aquifers are an important source of drinking water in the UK. Due to their properties, they are particularly vulnerable to groundwater-related hazards like floods and droughts. Understanding and predicting groundwater levels is therefore important for effective and safe water management. Chalk is known for its high porosity and, due to its dissolvability, exposed to karstification and strong subsurface heterogeneity. To cope with the karstic heterogeneity and limited data availability, specialised modelling approaches are required that balance model complexity and data availability. In this study, we present a novel approach to evaluate simulated groundwater level frequencies derived from a semi-distributed karst model that represents subsurface heterogeneity by distribution functions. Simulated groundwater storages are transferred into groundwater levels using evidence from different observations wells. Using a percentile approach we can assess the number of days exceeding or falling below selected groundwater level percentiles. Firstly, we evaluate the performance of the model when simulating groundwater level time series using a spilt sample test and parameter identifiability analysis. Secondly, we apply a split sample test to the simulated groundwater level percentiles to explore the performance in predicting groundwater level exceedances. We show that the model provides robust simulations of discharge and groundwater levels at three observation wells at a test site in a chalk-dominated catchment in south-western England. The second split sample test also indicates that the percentile approach is able to reliably predict groundwater level exceedances across all considered timescales up to their 75th percentile. However, when looking at the 90th percentile, it only provides acceptable predictions for long time periods and it fails when the 95th percentile of groundwater exceedance levels is considered. By modifying the historic forcings of our model

  15. Hydrogeology and simulation of ground-water flow at Arnold Air Force Base, Coffee and Franklin counties, Tennessee

    Science.gov (United States)

    Haugh, C.J.; Mahoney, E.N.

    1994-01-01

    The U.S. Air Force at Arnold Air Force Base (AAFB), in Coffee and Franklin Counties, Tennessee, is investigating ground-water contamination in selected areas of the base. This report documents the results of a comprehensive investigation of the regional hydrogeology of the AAFB area. Three aquifers within the Highland Rim aquifer system, the shallow aquifer, the Manchester aquifer, and the Fort Payne aquifer, have been identified in the study area. Of these, the Manchester aquifer is the primary source of water for domestic use. Drilling and water- quality data indicate that the Chattanooga Shale is an effective confining unit, isolating the Highland Rim aquifer system from the deeper, upper Central Basin aquifer system. A regional ground-water divide, approximately coinciding with the Duck River-Elk River drainage divide, underlies AAFB and runs from southwest to northeast. The general direction of most ground-water flow is to the north- west or to the northwest or to the southeast from the divide towards tributary streams that drain the area. Recharge estimates range from 4 to 11 inches per year. Digital computer modeling was used to simulate and provide a better understanding of the ground-water flow system. The model indicates that most of the ground-water flow occurs in the shallow and Manchester aquifers. The model was most sensitive to increases in hydraulic conductivity and changes in recharge rates. Particle-tracking analysis from selected sites of ground-water contamination indicates a potential for contami- nants to be transported beyond the boundary of AAFB.

  16. Numerical modeling of remediation of groundwater in a wellfield of in-situ leaching of uranium by pump-and-treat system

    International Nuclear Information System (INIS)

    Lv Junwen; Shi Wenge; Yang Yong

    2006-01-01

    Based on the hydrogeological conditions at the investigated site, the coupled mathematic model about the flow and the contaminant transportation in groundwater was established. The software Visual MODflow, the most popular simulation of groundwater flow and contaminant transportation, was used to study the contaminants distribution in groundwater during pumping at different pumping rates, and to determine the pumping well arrangement and optimal pumping rate, which directs the remediation of contaminated groundwater by the pump-and-treat system. (authors)

  17. Nitrate fluxes to groundwater under citrus orchards in a Mediterranean climate: Observations, calibrated models, simulations and agro-hydrological conclusions

    Science.gov (United States)

    Kurtzman, Daniel; Shapira, Roi H.; Bar-Tal, Asher; Fine, Pinchas; Russo, David

    2013-08-01

    Nitrate contamination of groundwater under land used for intensive-agriculture is probably the most worrisome agro-hydrological sustainability problem worldwide. Vadose-zone samples from 0 to 9 m depth under citrus orchards overlying an unconfined aquifer were analyzed for variables controlling water flow and the fate and transport of nitrogen fertilizers. Steady-state estimates of water and NO3-N fluxes to groundwater were found to vary spatially in the ranges of 90-330 mm yr- 1 and 50-220 kg ha- 1 yr- 1, respectively. Calibration of transient models to two selected vadose-zone profiles required limiting the concentration of NO3-N in the solution that is taken up by the roots to 30 mg L- 1. Results of an independent lysimeter experiment showed a similar nitrogen-uptake regime. Simulations of past conditions revealed a significant correlation between NO3-N flux to groundwater and the previous year's precipitation. Simulations of different nitrogen-application rates showed that using half of the nitrogen fertilizer added to the irrigation water by farmers would reduce average NO3-N flux to groundwater by 70%, decrease root nitrogen uptake by 20% and reduce the average pore water NO3-N concentration in the deep vadose zone to below the Israeli drinking water standard; hence this rate of nitrogen application was found to be agro-hydrologically sustainable. Beyond the investigation of nitrate fluxes to groundwater under citrus orchards and the interesting case-study aspects, this work demonstrates a methodology that enables skillful decisions concerning joint sustainability of both the water resource and agricultural production in a common environmental setting.

  18. Transport and potential attenuation of nitrogen in shallow groundwaters in the lower Rangitikei catchment, New Zealand

    Science.gov (United States)

    Collins, S.; Singh, R.; Rivas, A.; Palmer, A.; Horne, D.; Manderson, A.; Roygard, J.; Matthews, A.

    2017-11-01

    Intensive agricultural activities are generally associated with nitrogen leaching from agricultural soils, and this nitrogen has the potential to percolate and contaminate groundwater and surface waters. We assessed surface water and groundwater interactions, and nitrogen leaching and its potential attenuation in shallow groundwater in the lower Rangitikei River catchment (832 km2), New Zealand. We combined regional- and local-scale field surveys and experiments, nutrient budget modelling, and hydraulic and geochemical methods, to gain an insight into leaching, transformation and transport of nitrogen via groundwaters to the river in the study area. Concurrent river flow gaugings (in January 2015) and a piezometric map, developed from measured depths to groundwater in 110 bores (in October 2014), suggest groundwater discharges to the Rangitikei River in the upper parts of the study area, while there is groundwater recharge near the coast. The groundwater redox characterisation, based on sampling and analysis of 15 mostly shallow bores ( 5 m bgl), despite being installed under intensive land uses, such as dairying and cropping. Our in-field push-pull tests showed NO3-N reduction at four shallow groundwater piezometers, with the rates of reduction varying from 0.04 mg N L- 1 h-1 to 1.57 mg N L- 1 h-1. This highlights the importance of a sound understanding of not only the sources, but also transport and transformation, or fate, of nutrients leached from farms, to mitigate the likely impacts of land use on water quality and ecosystem health in agricultural catchments.

  19. Adaptive moving mesh methods for simulating one-dimensional groundwater problems with sharp moving fronts

    Science.gov (United States)

    Huang, W.; Zheng, Lingyun; Zhan, X.

    2002-01-01

    Accurate modelling of groundwater flow and transport with sharp moving fronts often involves high computational cost, when a fixed/uniform mesh is used. In this paper, we investigate the modelling of groundwater problems using a particular adaptive mesh method called the moving mesh partial differential equation approach. With this approach, the mesh is dynamically relocated through a partial differential equation to capture the evolving sharp fronts with a relatively small number of grid points. The mesh movement and physical system modelling are realized by solving the mesh movement and physical partial differential equations alternately. The method is applied to the modelling of a range of groundwater problems, including advection dominated chemical transport and reaction, non-linear infiltration in soil, and the coupling of density dependent flow and transport. Numerical results demonstrate that sharp moving fronts can be accurately and efficiently captured by the moving mesh approach. Also addressed are important implementation strategies, e.g. the construction of the monitor function based on the interpolation error, control of mesh concentration, and two-layer mesh movement. Copyright ?? 2002 John Wiley and Sons, Ltd.

  20. Grand challenge problems in environmental modeling and remediation: groundwater contaminant transport

    Energy Technology Data Exchange (ETDEWEB)

    Todd Arbogast; Steve Bryant; Clint N. Dawson; Mary F. Wheeler

    1998-08-31

    This report describes briefly the work of the Center for Subsurface Modeling (CSM) of the University of Texas at Austin (and Rice University prior to September 1995) on the Partnership in Computational Sciences Consortium (PICS) project entitled Grand Challenge Problems in Environmental Modeling and Remediation: Groundwater Contaminant Transport.

  1. Model Refinement and Simulation of Groundwater Flow in Clinton, Eaton, and Ingham Counties, Michigan

    Science.gov (United States)

    Luukkonen, Carol L.

    2010-01-01

    A groundwater-flow model that was constructed in 1996 of the Saginaw aquifer was refined to better represent the regional hydrologic system in the Tri-County region, which consists of Clinton, Eaton, and Ingham Counties, Michigan. With increasing demand for groundwater, the need to manage withdrawals from the Saginaw aquifer has become more important, and the 1996 model could not adequately address issues of water quality and quantity. An updated model was needed to better address potential effects of drought, locally high water demands, reduction of recharge by impervious surfaces, and issues affecting water quality, such as contaminant sources, on water resources and the selection of pumping rates and locations. The refinement of the groundwater-flow model allows simulations to address these issues of water quantity and quality and provides communities with a tool that will enable them to better plan for expansion and protection of their groundwater-supply systems. Model refinement included representation of the system under steady-state and transient conditions, adjustments to the estimated regional groundwater-recharge rates to account for both temporal and spatial differences, adjustments to the representation and hydraulic characteristics of the glacial deposits and Saginaw Formation, and updates to groundwater-withdrawal rates to reflect changes from the early 1900s to 2005. Simulations included steady-state conditions (in which stresses remained constant and changes in storage were not included) and transient conditions (in which stresses changed in annual and monthly time scales and changes in storage within the system were included). These simulations included investigation of the potential effects of reduced recharge due to impervious areas or to low-rainfall/drought conditions, delineation of contributing areas with recent pumping rates, and optimization of pumping subject to various quantity and quality constraints. Simulation results indicate

  2. The role of cation exchange in controlling groundwater chemistry at Aspo, Sweden

    International Nuclear Information System (INIS)

    Viani, B.E.; Bruton, C.J.

    1995-01-01

    Construction-induced groundwater flow has resulted in the mixing of relatively dilute shallow groundwater with more concentrated groundwater at depth in the underground Hard Rock Laboratory (HRL) at Aespoe, Sweden. The observed compositional variation of the mixed groundwater cannot be explained using a conservative mixing model. The geochemical modeling package EQ3/6, to which a cation-exchange model was added, was used to simulate mixing between the two fluids. The results of modeling simulations suggest that cation exchange between groundwater and fracture-lining clays can explain the major element fluid chemistry observed in the HRL. The quantity of exchanger required to match simulated with observed fluid chemistry is reasonable and is consistent with the observed fracture mineralogy. This preliminary study establishes cation exchange as a viable mechanism for controlling the chemical evolution of groundwaters in a fracture-dominated dynamic flow system. This modeling study also strengthens their confidence in the ability to model the potential effects of fracture-lining minerals on the transport of radionuclides in a high level nuclear waste repository

  3. Groundwater Flow and Transport Model in Cecina Plain (Tuscany, Italy using GIS processing

    Directory of Open Access Journals (Sweden)

    Riccardo Armellini

    2015-03-01

    Full Text Available This work provides a groundwater flow and transport model of trichlorethylene and tetrachlorethylene contamination in the Cecina’s coastal aquifer. The contamination analysis, with source located in the Poggio Gagliardo area (Montescudaio, Pisa, was necessary to optimize the groundwater monitoring and remediation design. The work was carried out in two phases: • design of a conceptual model of the aquifer using GIS analysis of many stratigraphic, chemical and hydrogeological data, collected from 2004 to 2012 in six aqueduct wells; • implementation of a groundwater flow and transport numerical model using the MODFLOW 88/96 and MT3D code and the graphical user interface GroundWaterVistas 5. The conceptual model hypothesizes a multilayer aquifer in the coastal plain extended to the sandy-clay hills, recharged by rainfall and by the Cecina River. The aquifer shows important hydrodynamic features affecting both the contamination spreading, due to the presence of a perched and heavily polluted layer separate from the underlying productive aquifer, and the hydrological balance, due to a thick separation layer that limits exchanges between the river and the second groundwater aquifer. The numerical model, built using increasingly complex versions of the initial conceptual model, has been calibrated using monitoring surveys conducted by the Environmental Protection Agency of Regione Toscana (ARPAT, in order to obtain possible forecast scenarios based on the minimum and maximum flow periods, and it is currently used as a tool for decision support regarding the reclamation and/or protection of the aquifer. Future developments will regard the implementation of the multilayer transport model, based on a new survey, and the final coupling with the regional hydrological model named MOBIDIC.

  4. Solute transport by groundwater flow to wetland ecosystems : the environmental impact of human activities

    NARCIS (Netherlands)

    Schot, P.P.

    1991-01-01

    This thesis deals with solute transport by groundwater flow and the way in which solute transport is affected by human activities. This in relation to wetland ecosystems. Wetlands in the eastern part of the Vecht river plain in The Netherlands are historically renown for their great variety of

  5. Estimation of the sources and flow system of groundwater in Fuji-Gotenba area by stable isotopic analysis and groundwater flow simulation

    International Nuclear Information System (INIS)

    Tomiyama, Shingo; Miyaike, Shusaku; Ii, Hiroyuki; Hattori, Ryota; Ito, Yuji

    2009-01-01

    Understanding the source and chemical character of the groundwater provides an important strategy for the quality management of mineral water and food materials. In order to identify a source and the flow paths of groundwater used for mineral water, the water quality and stable isotopes of hydrogen and oxygen of well water in Gotenba city were studied. The electrical conductivity and chemical character of sampled water are similar to those of well water and spring water discharged elsewhere around Mt. Fuji. The hydrogen and oxygen isotopic ratios of water samples indicate their origin to be solely meteoric and the oxygen isotopic ratios suggest that the groundwater mainly originated from the mountain-side of Mt. Fuji at altitudes of from 1500 m to 2300 m. A subsequent simulation of groundwater showed that the distribution of the total head and the Darcy velocity are down streamlines from mountain-sides toward the study area in Gotenba city. The altitudes of discharge obtained by the simulation are above 2000 m, and these correspond well with altitudes estimated from δ 18 O values of the samples. (author)

  6. Variable-density groundwater flow simulations and particle tracking. Numerical modelling using DarcyTools. Preliminary site description of the Simpevarp area, version 1.1

    International Nuclear Information System (INIS)

    Follin, Sven; Stigsson, Martin; Berglund, Sten; Svensson, Urban

    2004-12-01

    SKB is conducting site investigations for a high-level nuclear waste repository in fractured crystalline rocks at two coastal areas in Sweden, Forsmark and Simpevarp. The investigations started in 2002 and have been planned since the late 1990s. The work presented here investigates the possibility of using hydrogeochemical measurements in deep boreholes to reduce parameter uncertainty in a regional modelling of groundwater flow in fractured rock. The work was conducted with the aim of improving the palaeohydrogeological understanding of the Simpevarp area and to give recommendations to the preparations of the next version of the Preliminary Site Description (1.2). The study is based on a large number of numerical simulations of transient variable density groundwater flow through a strongly heterogeneous and anisotropic medium. The simulations were conducted with the computer code DarcyTools, the development of which has been funded by SKB. DarcyTools is a flexible porous media code specifically designed to treat groundwater flow and salt transport in sparsely fractured crystalline rock and it is noted that some of the features presented in this report are still under development or subjected to testing and verification. The simulations reveal the sensitivity of the results to different hydrogeological modelling assumptions, e.g. the sensitivity to the initial groundwater conditions at 10,000 BC, the size of the model domain and boundary conditions, and the hydraulic properties of deterministically and stochastically modelled deformation zones. The outcome of these simulations was compared with measured salinities and calculated relative proportions of different water types (mixing proportions) from measurements in two deep core drilled boreholes in the Laxemar subarea. In addition to the flow simulations, the statistics of flow related transport parameters were calculated for particle flowpaths from repository depth to ground surface for two subareas within the

  7. Variable-density groundwater flow simulations and particle tracking. Numerical modelling using DarcyTools. Preliminary site description of the Simpevarp area, version 1.1

    Energy Technology Data Exchange (ETDEWEB)

    Follin, Sven [SF GeoLogic AB, Stockholm (Sweden); Stigsson, Martin; Berglund, Sten [Swedish Nuclear Fuel and Waste Management Co., Stockholm (Sweden); Svensson, Urban [Computer-aided Fluid Engineering AB, Norrkoeping (Sweden)

    2004-12-01

    SKB is conducting site investigations for a high-level nuclear waste repository in fractured crystalline rocks at two coastal areas in Sweden, Forsmark and Simpevarp. The investigations started in 2002 and have been planned since the late 1990s. The work presented here investigates the possibility of using hydrogeochemical measurements in deep boreholes to reduce parameter uncertainty in a regional modelling of groundwater flow in fractured rock. The work was conducted with the aim of improving the palaeohydrogeological understanding of the Simpevarp area and to give recommendations to the preparations of the next version of the Preliminary Site Description (1.2). The study is based on a large number of numerical simulations of transient variable density groundwater flow through a strongly heterogeneous and anisotropic medium. The simulations were conducted with the computer code DarcyTools, the development of which has been funded by SKB. DarcyTools is a flexible porous media code specifically designed to treat groundwater flow and salt transport in sparsely fractured crystalline rock and it is noted that some of the features presented in this report are still under development or subjected to testing and verification. The simulations reveal the sensitivity of the results to different hydrogeological modelling assumptions, e.g. the sensitivity to the initial groundwater conditions at 10,000 BC, the size of the model domain and boundary conditions, and the hydraulic properties of deterministically and stochastically modelled deformation zones. The outcome of these simulations was compared with measured salinities and calculated relative proportions of different water types (mixing proportions) from measurements in two deep core drilled boreholes in the Laxemar subarea. In addition to the flow simulations, the statistics of flow related transport parameters were calculated for particle flowpaths from repository depth to ground surface for two subareas within the

  8. A model for managing sources of groundwater pollution

    Science.gov (United States)

    Gorelick, Steven M.

    1982-01-01

    The waste disposal capacity of a groundwater system can be maximized while maintaining water quality at specified locations by using a groundwater pollutant source management model that is based upon linear programing and numerical simulation. The decision variables of the management model are solute waste disposal rates at various facilities distributed over space. A concentration response matrix is used in the management model to describe transient solute transport and is developed using the U.S. Geological Survey solute transport simulation model. The management model was applied to a complex hypothetical groundwater system. Large-scale management models were formulated as dual linear programing problems to reduce numerical difficulties and computation time. Linear programing problems were solved using a numerically stable, available code. Optimal solutions to problems with successively longer management time horizons indicated that disposal schedules at some sites are relatively independent of the number of disposal periods. Optimal waste disposal schedules exhibited pulsing rather than constant disposal rates. Sensitivity analysis using parametric linear programing showed that a sharp reduction in total waste disposal potential occurs if disposal rates at any site are increased beyond their optimal values.

  9. Simple evaluation of groundwater flow and radionuclide transport at Aespoe

    International Nuclear Information System (INIS)

    Dverstorp, B.; Geier, J.; Voss, C.

    1996-12-01

    A simple evaluation of groundwater flux and potential for radionuclide transport at the Aespoe site, from fundamental hydrologic principles, indicates that, based upon data that are available from surface-based investigations, it is not possible to confirm that the bedrock has a high capacity to retard radionuclide release to the surface environment. This result is primarily due to the high spatial variability of hydraulic conductivity, and high uncertainty regarding the relationship among hydrologic and transport parameters within conductive elements of the bedrock. A comparison between Aespoe and seven other study sites in Sweden indicates that it is difficult or impossible to discriminate among these sites in terms of the geologic barrier function, based upon the types of data that are available from present-day methods of site characterization. Groundwater flux is evaluated by a one-dimensional application of Darcy's law to a set of simple, potential pathways for groundwater flow from the repository, which are chosen to yield an appraisal of the wide bounds of possible system behaviour. The configurations of the pathways are specified based on simple assumptions of flow-field structure, and hydraulic driving forces are specified from consideration of regional and local topographic differences. Results are expressed in terms of a parameter group that has been shown to control the barrier function. Comparisons with more detailed hydrological modelling of Aespoe show that, although a reduction in uncertainty is achieved, this reduction is not sufficient to distinguish between good and poor performance of the geologic barrier at the site. 38 refs

  10. Reassessment of Ground-Water Recharge and Simulated Ground-Water Availability for the Hawi Area of North Kohala, Hawaii

    Science.gov (United States)

    Oki, Delwyn S.

    2002-01-01

    An estimate of ground-water availability in the Hawi area of north Kohala, Hawaii, is needed to determine whether ground-water resources are adequate to meet future demand within the area and other areas to the south. For the Hawi area, estimated average annual recharge from infiltration of rainfall, fog drip, and irrigation is 37.5 million gallons per day from a daily water budget. Low and high annual recharge estimates for the Hawi area that incorporate estimated uncertainty are 19.9 and 55.4 million gallons per day, respectively. The recharge estimates from this study are lower than the recharge of 68.4 million gallons per day previously estimated from a monthly water budget. Three ground-water models, using the low, intermediate, and high recharge estimates (19.9, 37.5, and 55.4 million gallons per day, respectively), were developed for the Hawi area to simulate ground-water levels and discharges for the 1990?s. To assess potential ground-water availability, the numerical ground-water flow models were used to simulate the response of the freshwater-lens system to withdrawals at rates in excess of the average 1990?s withdrawal rates. Because of uncertainty in the recharge estimate, estimates of ground-water availability also are uncertain. Results from numerical simulations indicate that for appropriate well sites, depths, and withdrawal rates (1) for the low recharge estimate (19.9 million gallons per day) it may be possible to develop an additional 10 million gallons per day of fresh ground water from the Hawi area and maintain a freshwater-lens thickness of 160 feet near the withdrawal sites, (2) for the intermediate recharge estimate (37.5 million gallons per day) it may be possible to develop an additional 15 million gallons per day of fresh ground water from the Hawi area and maintain a freshwater-lens thickness of 190 feet near the withdrawal sites, and (3) for the high recharge estimate (55.4 million gallons per day) it may be possible to develop at

  11. Modelling the geochemical fate and transport of wastewater-derived phosphorus in contrasting groundwater systems

    Science.gov (United States)

    Spiteri, Claudette; Slomp, Caroline P.; Regnier, Pierre; Meile, Christof; Van Cappellen, Philippe

    2007-06-01

    A 1D reactive transport model (RTM) is used to obtain a mechanistic understanding of the fate of phosphorus (P) in the saturated zone of two contrasting aquifer systems. We use the field data from two oxic, electron donor-poor, wastewater-impacted, sandy Canadian aquifers, (Cambridge and Muskoka sites) as an example of a calcareous and non-calcareous groundwater system, respectively, to validate our reaction network. After approximately 10 years of wastewater infiltration, P is effectively attenuated within the first 10 m downgradient of the source mainly through fast sorption onto calcite and Fe oxides. Slow, kinetic sorption contributes further to P removal, while precipitation of phosphate minerals (strengite, hydroxyapatite) is quantitatively unimportant in the saturated zone. Nitrogen (N) dynamics are also considered, but nitrate behaves essentially as a conservative tracer in both systems. The model-predicted advancement of the P plume upon continued wastewater discharge at the calcareous site is in line with field observations. Model results suggest that, upon removal of the wastewater source, the P plume at both sites will persist for at least 20 years, owing to desorption of P from aquifer solids and the slow rate of P mineral precipitation. Sensitivity analyses for the non-calcareous scenario (Muskoka) illustrate the importance of the sorption capacity of the aquifer solids for P in modulating groundwater N:P ratios in oxic groundwater. The model simulations predict the breakthrough of groundwater with high P concentrations and low N:P ratios after 17 years at 20 m from the source for an aquifer with low sorption capacity (< 0.02% w/w Fe(OH) 3). In this type of system, denitrification plays a minor role in lowering the N:P ratios because it is limited by the availability of labile dissolved organic matter.

  12. Numerical simulation of the groundwater-flow system of the Kitsap Peninsula, west-central Washington

    Science.gov (United States)

    Frans, Lonna M.; Olsen, Theresa D.

    2016-05-05

    A groundwater-flow model was developed to improve understanding of water resources on the Kitsap Peninsula. The Kitsap Peninsula is in the Puget Sound lowland of west-central Washington, is bounded by Puget Sound on the east and by Hood Canal on the west, and covers an area of about 575 square miles. The peninsula encompasses all of Kitsap County, Mason County north of Hood Canal, and part of Pierce County west of Puget Sound. The peninsula is surrounded by saltwater, and the hydrologic setting is similar to that of an island. The study area is underlain by a thick sequence of unconsolidated glacial and interglacial deposits that overlie sedimentary and volcanic bedrock units that crop out in the central part of the study area. Twelve hydrogeologic units consisting of aquifers, confining units, and an underlying bedrock unit form the basis of the groundwater-flow model.Groundwater flow on the Kitsap Peninsula was simulated using the groundwater-flow model, MODFLOW‑NWT. The finite difference model grid comprises 536 rows, 362 columns, and 14 layers. Each model cell has a horizontal dimension of 500 by 500 feet, and the model contains a total of 1,227,772 active cells. Groundwater flow was simulated for transient conditions. Transient conditions were simulated for January 1985–December 2012 using annual stress periods for 1985–2004 and monthly stress periods for 2005–2012. During model calibration, variables were adjusted within probable ranges to minimize differences between measured and simulated groundwater levels and stream baseflows. As calibrated to transient conditions, the model has a standard deviation for heads and flows of 47.04 feet and 2.46 cubic feet per second, respectively.Simulated inflow to the model area for the 2005–2012 period from precipitation and secondary recharge was 585,323 acre-feet per year (acre-ft/yr) (93 percent of total simulated inflow ignoring changes in storage), and simulated inflow from stream and lake leakage was 43

  13. Simulation of groundwater flow in the glacial aquifer system of northeastern Wisconsin with variable model complexity

    Science.gov (United States)

    Juckem, Paul F.; Clark, Brian R.; Feinstein, Daniel T.

    2017-05-04

    The U.S. Geological Survey, National Water-Quality Assessment seeks to map estimated intrinsic susceptibility of the glacial aquifer system of the conterminous United States. Improved understanding of the hydrogeologic characteristics that explain spatial patterns of intrinsic susceptibility, commonly inferred from estimates of groundwater age distributions, is sought so that methods used for the estimation process are properly equipped. An important step beyond identifying relevant hydrogeologic datasets, such as glacial geology maps, is to evaluate how incorporation of these resources into process-based models using differing levels of detail could affect resulting simulations of groundwater age distributions and, thus, estimates of intrinsic susceptibility.This report describes the construction and calibration of three groundwater-flow models of northeastern Wisconsin that were developed with differing levels of complexity to provide a framework for subsequent evaluations of the effects of process-based model complexity on estimations of groundwater age distributions for withdrawal wells and streams. Preliminary assessments, which focused on the effects of model complexity on simulated water levels and base flows in the glacial aquifer system, illustrate that simulation of vertical gradients using multiple model layers improves simulated heads more in low-permeability units than in high-permeability units. Moreover, simulation of heterogeneous hydraulic conductivity fields in coarse-grained and some fine-grained glacial materials produced a larger improvement in simulated water levels in the glacial aquifer system compared with simulation of uniform hydraulic conductivity within zones. The relation between base flows and model complexity was less clear; however, the relation generally seemed to follow a similar pattern as water levels. Although increased model complexity resulted in improved calibrations, future application of the models using simulated particle

  14. Direct coupling of a genome-scale microbial in silico model and a groundwater reactive transport model

    International Nuclear Information System (INIS)

    Fang, Yilin; Scheibe, Timothy D.; Mahadevan, Radhakrishnan; Garg, Srinath; Long, Philip E.; Lovley, Derek R.

    2011-01-01

    The activity of microorganisms often plays an important role in dynamic natural attenuation or engineered bioremediation of subsurface contaminants, such as chlorinated solvents, metals, and radionuclides. To evaluate and/or design bioremediated systems, quantitative reactive transport models are needed. State-of-the-art reactive transport models often ignore the microbial effects or simulate the microbial effects with static growth yield and constant reaction rate parameters over simulated conditions, while in reality microorganisms can dynamically modify their functionality (such as utilization of alternative respiratory pathways) in response to spatial and temporal variations in environmental conditions. Constraint-based genome-scale microbial in silico models, using genomic data and multiple-pathway reaction networks, have been shown to be able to simulate transient metabolism of some well studied microorganisms and identify growth rate, substrate uptake rates, and byproduct rates under different growth conditions. These rates can be identified and used to replace specific microbially-mediated reaction rates in a reactive transport model using local geochemical conditions as constraints. We previously demonstrated the potential utility of integrating a constraint based microbial metabolism model with a reactive transport simulator as applied to bioremediation of uranium in groundwater. However, that work relied on an indirect coupling approach that was effective for initial demonstration but may not be extensible to more complex problems that are of significant interest (e.g., communities of microbial species, multiple constraining variables). Here, we extend that work by presenting and demonstrating a method of directly integrating a reactive transport model (FORTRAN code) with constraint-based in silico models solved with IBM ILOG CPLEX linear optimizer base system (C library). The models were integrated with BABEL, a language interoperability tool. The

  15. Characterization and simulation of fate and transport of selected volatile organic compounds in the vicinities of the Hadnot Point Industrial Area and landfill: Chapter A Supplement 6 in Analyses and historical reconstruction of groundwater flow, contaminant fate and transport, and distribution of drinking water within the service areas of the Hadnot Point and Holcomb Boulevard Water Treatment Plants and vicinities, U.S. Marine Corps Base Camp Lejeune, North Carolina

    Science.gov (United States)

    Jones, L. Elliott; Suárez-Soto, René J.; Anderson, Barbara A.; Maslia, Morris L.

    2013-01-01

    This supplement of Chapter A (Supplement 6) describes the reconstruction (i.e. simulation) of historical concentrations of tetrachloroethylene (PCE), trichloroethylene (TCE), and benzene3 in production wells supplying water to the Hadnot Base (USMCB) Camp Lejeune, North Carolina (Figure S6.1). A fate and transport model (i.e., MT3DMS [Zheng and Wang 1999]) was used to simulate contaminant migration from source locations through the groundwater system and to estimate mean contaminant concentrations in water withdrawn from water-supply wells in the vicinity of the Hadnot Point Industrial Area (HPIA) and the Hadnot Point landfill (HPLF) area.4 The reconstructed contaminant concentrations were subsequently input into a flow-weighted, materials mass balance (mixing) model (Masters 1998) to estimate monthly mean concentrations of the contaminant in finished water 5 at the HPWTP (Maslia et al. 2013). The calibrated fate and transport models described herein were based on and used groundwater velocities derived from groundwater-flow models that are described in Suárez-Soto et al. (2013). Information data pertinent to historical operations of water-supply wells are described in Sautner et al. (2013) and Telci et al. (2013).

  16. Residence times of groundwater and nitrate transport in coastal aquifer systems: Daweijia area, northeastern China.

    Science.gov (United States)

    Han, Dongmei; Cao, Guoliang; McCallum, James; Song, Xianfang

    2015-12-15

    Groundwater within the coastal aquifer systems of the Daweijia area in northeastern China is characterized by a large of variations (33-521mg/L) in NO3(-) concentrations. Elevated nitrate concentrations, in addition to seawater intrusion in the Daweijia well field, both attributable to anthropogenic activities, may impact future water-management practices. Chemical and stable isotopic (δ(18)O, δ(2)H) analysis, (3)H and CFCs methods were applied to provide a better understanding of the relationship between the distribution of groundwater mean residence time (MRT) and nitrate transport, and to identify sources of nitrate concentrations in the complex coastal aquifer systems. There is a relatively narrow range of isotopic composition (ranging from -8.5 to -7.0‰) in most groundwater. Generally higher tritium contents observed in the wet season relative to the dry season may result from rapid groundwater circulation in response to the rainfall through the preferential flow paths. In the well field, the relatively increased nitrate concentrations of groundwater, accompanied by the higher tritium contents in the wet season, indicate the nitrate pollution can be attributed to domestic wastes. The binary exponential and piston-flow mixing model (BEP) yielded feasible age distributions based on the conceptual model. The good inverse relationship between groundwater MRTs (92-467years) and the NO3(-) concentrations in the shallow Quaternary aquifers indicates that elevated nitrate concentrations are attributable to more recent recharge for shallow groundwater. However, there is no significant relationship between the MRTs (8-411years) and the NO3(-) concentrations existing in the carbonate aquifer system, due to the complex hydrogeological conditions, groundwater age distributions and the range of contaminant source areas. Nitrate in the groundwater system without denitrification effects could accumulate and be transported for tens of years, through the complex carbonate

  17. Simulating Lake-Groundwater Interactions During Decadal Climate Cycles: Accounting For Variable Lake Area In The Watershed

    Science.gov (United States)

    Virdi, M. L.; Lee, T. M.

    2009-12-01

    The volume and extent of a lake within the topo-bathymetry of a watershed can change substantially during wetter and drier climate cycles, altering the interaction of the lake with the groundwater flow system. Lake Starr and other seepage lakes in the permeable sandhills of central Florida are vulnerable to climate changes as they rely exclusively on rainfall and groundwater for inflows in a setting where annual rainfall and recharge vary widely. The groundwater inflow typically arrives from a small catchment area bordering the lake. The sinkhole origin of these lakes combined with groundwater pumping from underlying aquifers further complicate groundwater interactions. Understanding the lake-groundwater interactions and their effects on lake stage over multi-decadal climate cycles is needed to manage groundwater pumping and public expectation about future lake levels. The interdependence between climate, recharge, changing lake area and the groundwater catchment pose unique challenges to simulating lake-groundwater interactions. During the 10-year study period, Lake Starr stage fluctuated more than 13 feet and the lake surface area receded and expanded from 96 acres to 148 acres over drier and wetter years that included hurricanes, two El Nino events and a La Nina event. The recently developed Unsaturated Zone Flow (UZF1) and Lake (LAK7) packages for MODFLOW-2005 were used to simulate the changing lake sizes and the extent of the groundwater catchment contributing flow to the lake. The lake area was discretized to occupy the largest surface area at the highest observed stage and then allowed to change size. Lake cells convert to land cells and receive infiltration as receding lake area exposes the underlying unsaturated zone to rainfall and recharge. The unique model conceptualization also made it possible to capture the dynamic size of the groundwater catchment contributing to lake inflows, as the surface area and volume of the lake changed during the study

  18. Direct coupling of a genome-scale microbial in silico model and a groundwater reactive transport model.

    Science.gov (United States)

    Fang, Yilin; Scheibe, Timothy D; Mahadevan, Radhakrishnan; Garg, Srinath; Long, Philip E; Lovley, Derek R

    2011-03-25

    The activity of microorganisms often plays an important role in dynamic natural attenuation or engineered bioremediation of subsurface contaminants, such as chlorinated solvents, metals, and radionuclides. To evaluate and/or design bioremediated systems, quantitative reactive transport models are needed. State-of-the-art reactive transport models often ignore the microbial effects or simulate the microbial effects with static growth yield and constant reaction rate parameters over simulated conditions, while in reality microorganisms can dynamically modify their functionality (such as utilization of alternative respiratory pathways) in response to spatial and temporal variations in environmental conditions. Constraint-based genome-scale microbial in silico models, using genomic data and multiple-pathway reaction networks, have been shown to be able to simulate transient metabolism of some well studied microorganisms and identify growth rate, substrate uptake rates, and byproduct rates under different growth conditions. These rates can be identified and used to replace specific microbially-mediated reaction rates in a reactive transport model using local geochemical conditions as constraints. We previously demonstrated the potential utility of integrating a constraint-based microbial metabolism model with a reactive transport simulator as applied to bioremediation of uranium in groundwater. However, that work relied on an indirect coupling approach that was effective for initial demonstration but may not be extensible to more complex problems that are of significant interest (e.g., communities of microbial species and multiple constraining variables). Here, we extend that work by presenting and demonstrating a method of directly integrating a reactive transport model (FORTRAN code) with constraint-based in silico models solved with IBM ILOG CPLEX linear optimizer base system (C library). The models were integrated with BABEL, a language interoperability tool. The

  19. Direct coupling of a genome-scale microbial in silico model and a groundwater reactive transport model

    Science.gov (United States)

    Fang, Yilin; Scheibe, Timothy D.; Mahadevan, Radhakrishnan; Garg, Srinath; Long, Philip E.; Lovley, Derek R.

    2011-03-01

    The activity of microorganisms often plays an important role in dynamic natural attenuation or engineered bioremediation of subsurface contaminants, such as chlorinated solvents, metals, and radionuclides. To evaluate and/or design bioremediated systems, quantitative reactive transport models are needed. State-of-the-art reactive transport models often ignore the microbial effects or simulate the microbial effects with static growth yield and constant reaction rate parameters over simulated conditions, while in reality microorganisms can dynamically modify their functionality (such as utilization of alternative respiratory pathways) in response to spatial and temporal variations in environmental conditions. Constraint-based genome-scale microbial in silico models, using genomic data and multiple-pathway reaction networks, have been shown to be able to simulate transient metabolism of some well studied microorganisms and identify growth rate, substrate uptake rates, and byproduct rates under different growth conditions. These rates can be identified and used to replace specific microbially-mediated reaction rates in a reactive transport model using local geochemical conditions as constraints. We previously demonstrated the potential utility of integrating a constraint-based microbial metabolism model with a reactive transport simulator as applied to bioremediation of uranium in groundwater. However, that work relied on an indirect coupling approach that was effective for initial demonstration but may not be extensible to more complex problems that are of significant interest (e.g., communities of microbial species and multiple constraining variables). Here, we extend that work by presenting and demonstrating a method of directly integrating a reactive transport model (FORTRAN code) with constraint-based in silico models solved with IBM ILOG CPLEX linear optimizer base system (C library). The models were integrated with BABEL, a language interoperability tool. The

  20. FTRANS, Radionuclide Flow in Groundwater and Fractured Rock

    International Nuclear Information System (INIS)

    Huyakorn, P.; Golis, M.J.

    1987-01-01

    1 - Description of program or function: FTRANS (Fractured flow and Transport of Radionuclides) is a two-dimensional finite-element code designed to simulate ground-water flow and transport of radioactive nuclides in a fractured porous return medium. FTRANS takes into account fluid interactions between the fractures and porous matrix blocks, advective-dispersive transport in the fractures and diffusion in the porous matrix blocks, and chain reactions of radionuclide components. It has the capability to model the fractured system using either the dual-porosity or the discrete- fracture modeling approach or a combination of both. FTRANS can be used to perform two-dimensional near-field or far-field predictive analyses of ground-water flow and to perform risk assessments of radionuclide transport from nuclear waste repository subsystems to the biosphere. 2 - Restrictions on the complexity of the problem: Although FTRANS does cannot account for deformation processes which can affect the flow capacity and velocity field

  1. Summary of the data which is used for radionuclide transport analysis in the groundwater

    International Nuclear Information System (INIS)

    Koga, Osamu; Nagara, Shuichi; Matsumura, Toshihiro; Takeuchi, Akira; Takeda, Shinji; Sato, Kazuhiko; Tokizawa, Takayuki

    2004-03-01

    To analyze high precision in groundwater flow and radionuclide transport around Yotsugi open-pit mining place site and around Yotsugi mill tailing yard, besides the topic in past analysis is extracted, following it did examination of the corresponding method and arrangement of physical properties value. It investigated concerning the 3-dimensional flow and transport analysis code which can handle the chain-radionuclide selected. The range of the analytical area examined that become the object of groundwater flow and transport analysis, the wide area, Yotsugi open-pit mining place site and Yotsugi mill tailing yard selected the analytical model area, concerning the range which is surrounded with the divide. Receiving the influence of the alteration zone and the crush zone concerning the coefficient of permeability of the granite, it re-appraised excluding the value which is supposed that water permeability is high. The weathered granite from the lithofacies divided in the high weathered granite and the low weathered granite. As for the geometrical mean of coefficient of permeability of the former 10 -6 m/s order, the later 10 -8 m/s order, there is a difference of 2 orders in both. In addition, the data which is obtained to this year concerning physical properties value for analysis, groundwater level, precipitation and radionuclide density etc. rearranged and data set drew up. (author)

  2. Simulation of groundwater flow in the Edwards-Trinity and related aquifers in the Pecos County region, Texas

    Science.gov (United States)

    Clark, Brian R.; Bumgarner, Johnathan R.; Houston, Natalie A.; Foster, Adam L.

    2014-01-01

    The Edwards-Trinity aquifer is a vital groundwater resource for agricultural, industrial, and public supply uses in the Pecos County region of western Texas. The U.S. Geological Survey completed a comprehensive, integrated analysis of available hydrogeologic data to develop a numerical groundwater-flow model of the Edwards-Trinity and related aquifers in the study area in parts of Brewster, Jeff Davis, Pecos, and Reeves Counties. The active model area covers about 3,400 square miles of the Pecos County region of Texas west of the Pecos River, and its boundaries were defined to include the saturated areas of the Edwards-Trinity aquifer. The model is a five-layer representation of the Pecos Valley, Edwards-Trinity, Dockum, and Rustler aquifers. The Pecos Valley aquifer is referred to as the alluvial layer, and the Edwards-Trinity aquifer is divided into layers representing the Edwards part of the Edwards-Trinity aquifer and the Trinity part of the Edwards-Trinity aquifer, respectively. The calibration period of the simulation extends from 1940 to 2010. Simulated hydraulic heads generally were in good agreement with observed values; 1,684 out of 2,860 (59 percent) of the simulated values were within 25 feet of the observed value. The average root mean square error value of hydraulic head for the Edwards-Trinity aquifer was 34.2 feet, which was approximately 4 percent of the average total observed change in groundwater-level altitude (groundwater level). Simulated spring flow representing Comanche Springs exhibits a pattern similar to observed spring flow. Independent geochemical modeling corroborates results of simulated groundwater flow that indicates groundwater in the Edwards-Trinity aquifer in the Leon-Belding and Fort Stockton areas is a mixture of recharge from the Barilla and Davis Mountains and groundwater that has upwelled from the Rustler aquifer.

  3. Numerical simulation of groundwater flow in the Columbia Plateau Regional Aquifer System, Idaho, Oregon, and Washington

    Science.gov (United States)

    Ely, D. Matthew; Burns, Erick R.; Morgan, David S.; Vaccaro, John J.

    2014-01-01

    A three-dimensional numerical model of groundwater flow was constructed for the Columbia Plateau Regional Aquifer System (CPRAS), Idaho, Oregon, and Washington, to evaluate and test the conceptual model of the system and to evaluate groundwater availability. The model described in this report can be used as a tool by water-resource managers and other stakeholders to quantitatively evaluate proposed alternative management strategies and assess the long‑term availability of groundwater. The numerical simulation of groundwater flow in the CPRAS was completed with support from the Groundwater Resources Program of the U.S. Geological Survey Office of Groundwater.

  4. An isotopic view of water and nitrate transport through the vadose zone in Oregon's southern Willamette Valley's Groundwater Management Area

    Science.gov (United States)

    Brooks, J. R.; Pearlstein, S.; Hutchins, S.; Faulkner, B. R.; Rugh, W.; Willard, K.; Coulombe, R.; Compton, J.

    2017-12-01

    Groundwater nitrate contamination affects thousands of households in Oregon's southern Willamette Valley and many more across the USA. The southern Willamette Valley Groundwater Management Area (GWMA) was established in 2004 due to nitrate levels in the groundwater exceeding the human health standard of 10 mg nitrate-N L-1. Much of the nitrogen (N) inputs to the GWMA comes from agricultural fertilizers, and thus efforts to reduce N inputs to groundwater are focused upon improving N management. However, the effectiveness of these improvements on groundwater quality is unclear because of the complexity of nutrient transport through the vadose zone and long groundwater residence times. Our objective was to focus on vadose zone transport and understand the dynamics and timing of N and water movement below the rooting zone in relation to N management and water inputs. Stable isotopes are a powerful tool for tracking water movement, and understanding N transformations. In partnership with local farmers and state agencies, we established lysimeters and groundwater wells in multiple agricultural fields in the GWMA, and have monitored nitrate, nitrate isotopes, and water isotopes weekly for multiple years. Our results indicate that vadose zone transport is highly complex, and the residence time of water collected in lysimeters was much longer than expected. While input precipitation water isotopes were highly variable over time, lysimeter water isotopes were surprisingly consistent, more closely resembling long-term precipitation isotope means rather than recent precipitation isotopic signatures. However, some particularly large precipitation events with unique isotopic signatures revealed high spatial variability in transport, with some lysimeters showing greater proportions of recent precipitation inputs than others. In one installation where we have groundwater wells and lysimeters at multiple depths, nitrate/nitrite concentrations decreased with depth. N concentrations

  5. Discrete Fracture Network Modeling and Simulation of Subsurface Transport for the Topopah Springs and Lava Flow Aquifers at Pahute Mesa, FY 15 Progress Report

    Energy Technology Data Exchange (ETDEWEB)

    Makedonska, Nataliia [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Kwicklis, Edward Michael [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Birdsell, Kay Hanson [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Harrod, Jeremy Ashcraft [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Karra, Satish [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-10-18

    This progress report for fiscal year 2015 (FY15) describes the development of discrete fracture network (DFN) models for Pahute Mesa. DFN models will be used to upscale parameters for simulations of subsurface flow and transport in fractured media in Pahute Mesa. The research focuses on modeling of groundwater flow and contaminant transport using DFNs generated according to fracture characteristics observed in the Topopah Spring Aquifer (TSA) and the Lava Flow Aquifer (LFA). This work will improve the representation of radionuclide transport processes in large-scale, regulatory-focused models with a view to reduce pessimistic bounding approximations and provide more realistic contaminant boundary calculations that can be used to describe the future extent of contaminated groundwater. Our goal is to refine a modeling approach that can translate parameters to larger-scale models that account for local-scale flow and transport processes, which tend to attenuate migration.

  6. Numerical Simulation of Groundwater Flow at Kori Nuclear Power Plant Site

    International Nuclear Information System (INIS)

    Sohn, Wook; Sohn, Soon Whan; Chon, Chul Min; Kim, Kue Youn

    2010-01-01

    Recently, the understanding of hydrogeological characteristics of nuclear power sites is getting more importance with increasing public concerns over the environment since such understanding is essential for an environmentally friendly operation of plants. For such understanding, the prediction of groundwater flow pattern onsite plays the most critical role since it is the most dynamic of the factors to be considered. In this study, the groundwater flow at the Kori Plant 1 site has been simulated numerically with aim of providing fundamental information needed for improving the understanding of the hydrogeological characteristics of the site

  7. Three-dimensional analysis of future groundwater flow conditions and contaminant plume transport in the Hanford Site unconfined aquifer system: FY 1996 and 1997 status report

    Energy Technology Data Exchange (ETDEWEB)

    Cole, C.R.; Wurstner, S.K.; Williams, M.D.; Thorne, P.D.; Bergeron, M.P.

    1997-12-01

    A three-dimensional numerical model of groundwater flow and transport, based on the Coupled Fluid Energy, and Solute Transport (CFEST) code, was developed for the Hanford Site to support the Hanford Groundwater Project (HGWP), managed by Pacific Northwest National Laboratory. The model was developed to increase the understanding and better forecast the migration of several contaminant plumes being monitored by the HGWP, and to support the Hanford Site Composite Analysis for low-level waste disposal in the 200-Area Plateau. Recent modeling efforts have focused on continued refinement of an initial version of the three-dimensional model developed in 1995 and its application to simulate future transport of selected contaminant plumes in the aquifer system. This version of the model was updated using a more current version of the CFEST code called CFEST96. Prior to conducting simulations of contaminant transport with the three-dimensional model, a previous steady-state, two-dimensional model of the unconfined aquifer system was recalibrated to 1979 water-table conditions with a statistical inverse method implemented in the CFEST-INV computer code. The results of the recalibration were used to refine the three-dimensional conceptual model and to calibrate it with a conceptualization that preserves the two-dimensional hydraulic properties and knowledge of the aquifer`s three-dimensional properties for the same 1979 water-table conditions. The transient behavior of the three-dimensional flow model was also calibrated by adjusting model storage properties (specific yield) until transient water-table predictions approximated observed water-table elevations between 1979 and 1996.

  8. Three-dimensional analysis of future groundwater flow conditions and contaminant plume transport in the Hanford Site unconfined aquifer system: FY 1996 and 1997 status report

    International Nuclear Information System (INIS)

    Cole, C.R.; Wurstner, S.K.; Williams, M.D.; Thorne, P.D.; Bergeron, M.P.

    1997-12-01

    A three-dimensional numerical model of groundwater flow and transport, based on the Coupled Fluid Energy, and Solute Transport (CFEST) code, was developed for the Hanford Site to support the Hanford Groundwater Project (HGWP), managed by Pacific Northwest National Laboratory. The model was developed to increase the understanding and better forecast the migration of several contaminant plumes being monitored by the HGWP, and to support the Hanford Site Composite Analysis for low-level waste disposal in the 200-Area Plateau. Recent modeling efforts have focused on continued refinement of an initial version of the three-dimensional model developed in 1995 and its application to simulate future transport of selected contaminant plumes in the aquifer system. This version of the model was updated using a more current version of the CFEST code called CFEST96. Prior to conducting simulations of contaminant transport with the three-dimensional model, a previous steady-state, two-dimensional model of the unconfined aquifer system was recalibrated to 1979 water-table conditions with a statistical inverse method implemented in the CFEST-INV computer code. The results of the recalibration were used to refine the three-dimensional conceptual model and to calibrate it with a conceptualization that preserves the two-dimensional hydraulic properties and knowledge of the aquifer's three-dimensional properties for the same 1979 water-table conditions. The transient behavior of the three-dimensional flow model was also calibrated by adjusting model storage properties (specific yield) until transient water-table predictions approximated observed water-table elevations between 1979 and 1996

  9. Concept on groundwater flow and mass transport through heterogeneous porous media and application to in-situ test analysis

    International Nuclear Information System (INIS)

    Hatanaka, Koichiro; Umeki, Hiroyuki.

    1995-01-01

    Generally, geological media is modelled as porous or fractured media depending on their characteristics. Since the channels of groundwater flow and the transport paths are determined by the heterogeneity of the geological media, quantitative understanding of the heterogeneity is an important issue for modelling flow and transport processes through them. Therefore, it becomes popular way to develop statistical identification approaches of the heterogeneous field by using data from in-situ test and conduct validation studies of flow and transport models through the field by comparing with observed data. In this report, the theories of the identification approach and the concept on groundwater flow and mass transport are explained briefly and the application to tracer tests conducted at Grimsel test site, Switzerland, are described. (author)

  10. Numerical simulation of seasonal heat storage in a contaminated shallow aquifer - Temperature influence on flow, transport and reaction processes

    Science.gov (United States)

    Popp, Steffi; Beyer, Christof; Dahmke, Andreas; Bauer, Sebastian

    2015-04-01

    The energy market in Germany currently faces a rapid transition from nuclear power and fossil fuels towards an increased production of energy from renewable resources like wind or solar power. In this context, seasonal heat storage in the shallow subsurface is becoming more and more important, particularly in urban regions with high population densities and thus high energy and heat demand. Besides the effects of increased or decreased groundwater and sediment temperatures on local and large-scale groundwater flow, transport, geochemistry and microbiology, an influence on subsurface contaminations, which may be present in the urban surbsurface, can be expected. Currently, concerns about negative impacts of temperature changes on groundwater quality are the main barrier for the approval of heat storage at or close to contaminated sites. The possible impacts of heat storage on subsurface contamination, however, have not been investigated in detail yet. Therefore, this work investigates the effects of a shallow seasonal heat storage on subsurface groundwater flow, transport and reaction processes in the presence of an organic contamination using numerical scenario simulations. A shallow groundwater aquifer is assumed, which consists of Pleistoscene sandy sediments typical for Northern Germany. The seasonal heat storage in these scenarios is performed through arrays of borehole heat exchangers (BHE), where different setups with 6 and 72 BHE, and temperatures during storage between 2°C and 70°C are analyzed. The developing heat plume in the aquifer interacts with a residual phase of a trichloroethene (TCE) contamination. The plume of dissolved TCE emitted from this source zone is degraded by reductive dechlorination through microbes present in the aquifer, which degrade TCE under anaerobic redox conditions to the degradation products dichloroethene, vinyl chloride and ethene. The temperature dependence of the microbial degradation activity of each degradation step is

  11. Improved regional-scale groundwater representation by the coupling of the mesoscale Hydrologic Model (mHM v5.7) to the groundwater model OpenGeoSys (OGS)

    Science.gov (United States)

    Jing, Miao; Heße, Falk; Kumar, Rohini; Wang, Wenqing; Fischer, Thomas; Walther, Marc; Zink, Matthias; Zech, Alraune; Samaniego, Luis; Kolditz, Olaf; Attinger, Sabine

    2018-06-01

    Most large-scale hydrologic models fall short in reproducing groundwater head dynamics and simulating transport process due to their oversimplified representation of groundwater flow. In this study, we aim to extend the applicability of the mesoscale Hydrologic Model (mHM v5.7) to subsurface hydrology by coupling it with the porous media simulator OpenGeoSys (OGS). The two models are one-way coupled through model interfaces GIS2FEM and RIV2FEM, by which the grid-based fluxes of groundwater recharge and the river-groundwater exchange generated by mHM are converted to fixed-flux boundary conditions of the groundwater model OGS. Specifically, the grid-based vertical reservoirs in mHM are completely preserved for the estimation of land-surface fluxes, while OGS acts as a plug-in to the original mHM modeling framework for groundwater flow and transport modeling. The applicability of the coupled model (mHM-OGS v1.0) is evaluated by a case study in the central European mesoscale river basin - Nägelstedt. Different time steps, i.e., daily in mHM and monthly in OGS, are used to account for fast surface flow and slow groundwater flow. Model calibration is conducted following a two-step procedure using discharge for mHM and long-term mean of groundwater head measurements for OGS. Based on the model summary statistics, namely the Nash-Sutcliffe model efficiency (NSE), the mean absolute error (MAE), and the interquartile range error (QRE), the coupled model is able to satisfactorily represent the dynamics of discharge and groundwater heads at several locations across the study basin. Our exemplary calculations show that the one-way coupled model can take advantage of the spatially explicit modeling capabilities of surface and groundwater hydrologic models and provide an adequate representation of the spatiotemporal behaviors of groundwater storage and heads, thus making it a valuable tool for addressing water resources and management problems.

  12. Assessment of applications of transport models on regional scale solute transport

    Science.gov (United States)

    Guo, Z.; Fogg, G. E.; Henri, C.; Pauloo, R.

    2017-12-01

    Regional scale transport models are needed to support the long-term evaluation of groundwater quality and to develop management strategies aiming to prevent serious groundwater degradation. The purpose of this study is to evaluate the capacity of previously-developed upscaling approaches to accurately describe main solute transport processes including the capture of late-time tails under changing boundary conditions. Advective-dispersive contaminant transport in a 3D heterogeneous domain was simulated and used as a reference solution. Equivalent transport under homogeneous flow conditions were then evaluated applying the Multi-Rate Mass Transfer (MRMT) model. The random walk particle tracking method was used for both heterogeneous and homogeneous-MRMT scenarios under steady state and transient conditions. The results indicate that the MRMT model can capture the tails satisfactorily for plume transported with ambient steady-state flow field. However, when boundary conditions change, the mass transfer model calibrated for transport under steady-state conditions cannot accurately reproduce the tailing effect observed for the heterogeneous scenario. The deteriorating impact of transient boundary conditions on the upscaled model is more significant for regions where flow fields are dramatically affected, highlighting the poor applicability of the MRMT approach for complex field settings. Accurately simulating mass in both mobile and immobile zones is critical to represent the transport process under transient flow conditions and will be the future focus of our study.

  13. Neutron transportation simulator

    International Nuclear Information System (INIS)

    Uenohara, Yuzo.

    1995-01-01

    In the present invention, problems in an existent parallelized monte carlo method is solved, and behaviors of neutrons in a large scaled system are accurately simulated at a high speed. Namely, a neutron transportation simulator according to the monte carlo method simulates movement of each of neutrons by using a parallel computer. In this case, the system to be processed is divided based on a space region and an energy region to which neutrons belong. Simulation of neutrons in the divided regions is allotted to each of performing devices of the parallel computer. Tarry data and nuclear data of the neutrons in each of the regions are memorized dispersedly to memories of each of the performing devices. A transmission means for simulating the behaviors of the neutrons in the region by each of the performing devices, as well as transmitting the information of the neutrons, when the neutrons are moved to other region, to the performing device in a transported portion are disposed to each of the performing devices. With such procedures, simulation for the neutrons in the allotted region can be conducted with small capacity of memories. (I.S.)

  14. Scoping calculations for groundwater transport of tritium from the Gnome Site, New Mexico

    International Nuclear Information System (INIS)

    Pohlmann, K.; Andricevic, R.

    1994-08-01

    Analytic solutions are employed to investigate potential groundwater transport of tritium from a radioactive tracer site near the Project Gnome site in southeastern New Mexico. The tracer test was conducted in 1963 and introduced significant quantities of radionuclides to the transmissive and laterally continuous Culebra dolomite. Groundwater in the Culebra near Gnome travels toward a regional discharge point at the Pecos River, a distance of about 10 to 15 km, depending on flow path. Groundwater transport of radionuclides from the Gnome site is therefore of interest due to the proximity of the accessible environment and the 31-year time period during which migration is likely to have occurred. The analytical stochastic solutions used incorporate the heterogeneity observed in the Culebra by treating transmissivity as a spatially correlated random field. The results indicate that significant spreading of tritium will occur in the Culebra dolomite as a result of the combination of relatively high transmissivity, high spatial variability, and high spatial correlation of transmissivity. Longitudinal spreading may cause a very small fraction of tritium mass to arrive at the Pecos River within the 31 years since the tracer test. However, dilution and transverse dispersion will act to distribute this mass over a very large volume, thereby reducing groundwater concentrations. Despite the high degree of spreading, the calculations indicate that most of the tritium remains near the source. At present, the center of mass is estimated to have moved approximately 260 m downgradient of the test location and about 95 percent of the mass is estimated to have remained within about 1 km downgradient

  15. Vadose Zone Nitrate Transport Dynamics Resulting from Agricultural Groundwater Banking

    Science.gov (United States)

    Murphy, N. P.; McLaughlin, S.; Dahlke, H. E.

    2017-12-01

    In recent years, California's increased reliance on groundwater resources to meet agricultural and municipal demands has resulted in significant overdraft and water quality issues. Agricultural groundwater banking (AGB) has emerged as a promising groundwater replenishment opportunity in California; AGB is a form of managed aquifer recharge where farmland is flooded during the winter using excess surface water in order to recharge the underlying groundwater. Suitable farmland that is connected to water delivery systems is available for AGB throughout the Central Valley. However, questions remain how AGB could be implemented on fertilized agricultural fields such that nitrate leaching from the root zone is minimized. Here, we present results from field and soil column studies that investigate the transport dynamics of nitrogen in the root and deeper vadose zone during flooding events. We are specifically interested in estimating how timing and duration of flooding events affect percolation rates, leaching and nitrification/denitrification processes in three soil types within the Central Valley. Laboratory and field measurements include nitrogen (NO3-, NH4+, NO2-, N2O), redox potentials, total organic carbon, dissolved oxygen, moisture content and EC. Soil cores are collected in the field before and after recharge events up to a depth of 4m, while other sensors monitor field conditions continuously. Preliminary results from the three field sites show that significant portions of the applied floodwater (12-62 cm) infiltrated below the root zone: 96.1% (Delhi), 88.6% (Modesto) and 76.8% (Orland). Analysis of the soil cores indicate that 70% of the residual nitrate was flushed from the sandy soil, while the fine sandy loam showed only a 5% loss and in some cores even an increase in soil nitrate (in the upper 20cm). Column experiments support these trends and indicate that increases in soil nitrate in the upper root zone might be due to organic nitrogen mineralization and

  16. Pollutants transport and distribution studies in groundwater system by nuclear, geophysics and hydrogeochemical methods

    International Nuclear Information System (INIS)

    Mohd Tadza Abdul Rahman; Daud Mohamad

    2000-01-01

    In Malaysia, the most common means of managing municipal refuse is by dumping it indiscriminately in piles on the selected open land. Leachate that is formed primarily in association with precipitation that infiltrates through the refuse normally results in the migration of leachate into underlying groundwater zone. The study of pollutant transport derived from domestic refuse and their impact on water quality in groundwater system has been performed in a selected landfill site at Gemencheh, Negeri Sembilan. The study involved the determination of flow velocity and flow direction of pollutants by nuclear techniques and a detail survey by geophysical method as well as hydrogeochemical approach as a supporting evidence of pollution occurrence. Hydrogeochemical approach involved the determination of pollutants species such as chloride and nitrate. A network of about 30 observation points had been identified and sampled. The results of the study have shown that the pollutants were concentrated at the middle of the dumping site and transported with the flow velocity between 0.2-15.4 metres per day toward northeast direction. Furthermore, the study established that the municipal or domestic landfalls are considered as one of the potential sources of groundwater pollution in Malaysia

  17. A residence-time-based transport approach for the groundwater pathway in performance assessment models

    Science.gov (United States)

    Robinson, Bruce A.; Chu, Shaoping

    2013-03-01

    This paper presents the theoretical development and numerical implementation of a new modeling approach for representing the groundwater pathway in risk assessment or performance assessment model of a contaminant transport system. The model developed in the present study, called the Residence Time Distribution (RTD) Mixing Model (RTDMM), allows for an arbitrary distribution of fluid travel times to be represented, to capture the effects on the breakthrough curve of flow processes such as channelized flow and fast pathways and complex three-dimensional dispersion. Mathematical methods for constructing the model for a given RTD are derived directly from the theory of residence time distributions in flowing systems. A simple mixing model is presented, along with the basic equations required to enable an arbitrary RTD to be reproduced using the model. The practical advantages of the RTDMM include easy incorporation into a multi-realization probabilistic simulation; computational burden no more onerous than a one-dimensional model with the same number of grid cells; and straightforward implementation into available flow and transport modeling codes, enabling one to then utilize advanced transport features of that code. For example, in this study we incorporated diffusion into the stagnant fluid in the rock matrix away from the flowing fractures, using a generalized dual porosity model formulation. A suite of example calculations presented herein showed the utility of the RTDMM for the case of a radioactive decay chain, dual porosity transport and sorption.

  18. Isotope and chemical tracers in groundwater hydrology

    International Nuclear Information System (INIS)

    Kendall, C.; Stewart, M.K.; Morgenstern, U.; Trompetter, V.

    1999-01-01

    The course sessions cover: session 1, Fundamentals of stable and radioactive isotopes; session 2, Stable oxygen and hydrogen isotopes in hydrology: background, examples, sampling strategy; session 3, Catchment studies using oxygen and hydrogen isotopes: background - the hydrologic water balance, evapotranspiration - the lion's share, runoff generation - new water/old water fractions, groundwater recharge - the crumbs; session 4, Isotopes in catchment hydrology: survey of applications, future developments; session 5, Applications of tritium in hydrology: background and measurement, interpretation, examples; session 6, Case studies using mixing models: Hutt Valley groundwater system, an extended mixing model for simulating tracer transport in the unsaturated zone; session 7, Groundwater dating using CFC concentrations: background, sampling and measurement, use and applications; session 8, Groundwater dating with carbon-14: background, sampling and measurement, use and applications; session 9, NZ case studies: Tauranga warm springs, North Canterbury Plains groundwater; session 10, Stable carbon and nitrogen isotopes: background and examples, biological applications of C-N-S isotopes; session 11, New developments in isotope hydrology: gas isotopes, compound specific applications, age dating of sediments etc; session 12, NZ case studies: North Canterbury Plains groundwater (continued), Waimea Plains groundwater. (author). refs., figs

  19. Coupling a groundwater model with a land surface model to improve water and energy cycle simulation

    Directory of Open Access Journals (Sweden)

    W. Tian

    2012-12-01

    Full Text Available Water and energy cycles interact, making these two processes closely related. Land surface models (LSMs can describe the water and energy cycles on the land surface, but their description of the subsurface water processes is oversimplified, and lateral groundwater flow is ignored. Groundwater models (GWMs describe the dynamic movement of the subsurface water well, but they cannot depict the physical mechanisms of the evapotranspiration (ET process in detail. In this study, a coupled model of groundwater flow with a simple biosphere (GWSiB is developed based on the full coupling of a typical land surface model (SiB2 and a 3-D variably saturated groundwater model (AquiferFlow. In this coupled model, the infiltration, ET and energy transfer are simulated by SiB2 using the soil moisture results from the groundwater flow model. The infiltration and ET results are applied iteratively to drive the groundwater flow model. After the coupled model is built, a sensitivity test is first performed, and the effect of the groundwater depth and the hydraulic conductivity parameters on the ET are analyzed. The coupled model is then validated using measurements from two stations located in shallow and deep groundwater depth zones. Finally, the coupled model is applied to data from the middle reach of the Heihe River basin in the northwest of China to test the regional simulation capabilities of the model.

  20. Geochemistry and the Understanding of Groundwater Systems

    Science.gov (United States)

    Glynn, P. D.; Plummer, L. N.; Weissmann, G. S.; Stute, M.

    2009-12-01

    Geochemical techniques and concepts have made major contributions to the understanding of groundwater systems. Advances continue to be made through (1) development of measurement and characterization techniques, (2) improvements in computer technology, networks and numerical modeling, (3) investigation of coupled geologic, hydrologic, geochemical and biologic processes, and (4) scaling of individual observations, processes or subsystem models into larger coherent model frameworks. Many applications benefit from progress in these areas, such as: (1) understanding paleoenvironments, in particular paleoclimate, through the use of groundwater archives, (2) assessing the sustainability (recharge and depletion) of groundwater resources, and (3) their vulnerability to contamination, (4) evaluating the capacity and consequences of subsurface waste isolation (e.g. geologic carbon sequestration, nuclear and chemical waste disposal), (5) assessing the potential for mitigation/transformation of anthropogenic contaminants in groundwater systems, and (6) understanding the effect of groundwater lag times in ecosystem-scale responses to natural events, land-use changes, human impacts, and remediation efforts. Obtaining “representative” groundwater samples is difficult and progress in obtaining “representative” samples, or interpreting them, requires new techniques in characterizing groundwater system heterogeneity. Better characterization and simulation of groundwater system heterogeneity (both physical and geochemical) is critical to interpreting the meaning of groundwater “ages”; to understanding and predicting groundwater flow, solute transport, and geochemical evolution; and to quantifying groundwater recharge and discharge processes. Research advances will also come from greater use and progress (1) in the application of environmental tracers to ground water dating and in the analysis of new geochemical tracers (e.g. compound specific isotopic analyses, noble gas

  1. Groundwater Salinity Simulation of a Subsurface Reservoir in Taiwan

    Science.gov (United States)

    Fang, H. T.

    2015-12-01

    The subsurface reservoir is located in Chi-Ken Basin, Pescadores (a group islands located at western part of Taiwan). There is no river in these remote islands and thus the freshwater supply is relied on the subsurface reservoir. The basin area of the subsurface reservoir is 2.14 km2 , discharge of groundwater is 1.27×106m3 , annual planning water supplies is 7.9×105m3 , which include for domestic agricultural usage. The annual average temperature is 23.3oC, average moisture is 80~85%, annual average rainfall is 913 mm, but ET rate is 1975mm. As there is no single river in the basin; the major recharge of groundwater is by infiltration. Chi-Ken reservoir is the first subsurface reservoir in Taiwan. Originally, the water quality of the reservoir is good. The reservoir has had the salinity problem since 1991 and it became more and more serious from 1992 until 1994. Possible reason of the salinity problem was the shortage of rainfall or the leakage of the subsurface barrier which caused the seawater intrusion. The present study aimed to determine the leakage position of subsurface barrier that caused the salinity problem. In order to perform the simulation for different possible leakage position of the subsurface reservoir, a Groundwater Modeling System (GMS) is used to define soils layer data, hydro-geological parameters, initial conditions, boundary conditions and the generation of three dimension meshes. A three dimension FEMWATER(Yeh , 1996) numerical model was adopted to find the possible leakage position of the subsurface barrier and location of seawater intrusion by comparing the simulation of different possible leakage with the observations. 1.By assuming the leakage position in the bottom of barrier, the simulated numerical result matched the observation better than the other assumed leakage positions. It showed that the most possible leakage position was at the bottom of the barrier. 2.The research applied three dimension FEMWATER and GMS as an interface

  2. Laboratory Eh simulations in relation to the Redox conditions in natural granitic groundwaters

    International Nuclear Information System (INIS)

    Wikberg, P.

    1992-01-01

    Redox conditions are one of the prime parameters affecting the sorption of radionuclides released from a nuclear waste repository. The swedish granitic groundwaters are all reducing from a depth of approximately 100 m, the vast majority already from a depth of a few tens of metres. The contents of ferrous iron reaches a maximum at the same depth due to the weathering of iron rich minerals. At greater depths the iron content decreases while sulphide contents increases. The redox buffering capacity (in groundwater) lies mainly in the rock. The contents of iron, sulphide and manganese constitute the buffer in the groundwater. The redox potential (Eh) is controlled by the iron system in the groundwater and the rock. Sulphate is not involved in the groundwater redox processes. Laboratory simulations of the groundwater rock interactions with respect to the redox conditions have been realized, but there is still a difference compared to the natural system. This difference is due to the fact that traces of oxygen diffuses into the laboratory system causing a continuous oxidation. 20 refs., 4 figs., 1 tab

  3. Using Flux Information at Surface Water Boundaries to Improve a Groundwater Flow and Transport Model

    National Research Council Canada - National Science Library

    Genereux, David

    2000-01-01

    We investigated the performance of a groundwater flow and solute transport model when different combinations of hydraulic head, seepage flux, and chloride concentration data were used in calibration of the model...

  4. Hydrogeology and simulation of ground-water flow near the Lantana Landfill, Palm Beach County, Florida

    Science.gov (United States)

    Russell, G.M.; Wexler, E.J.

    1993-01-01

    The Lantana landfill in Palm Beach County has a surface that is 40 to 50 feet above original ground level and consists of about 250 acres of compacted garbage and trash. Parts of the landfill are below the water table. Surface-resistivity measurements and water-quality analyses indicate that leachate-enriched ground water along the eastern perimeter of the landfill has moved about 500 feet eastward toward an adjacent lake. Concentrations of chloride and nutrients within the leachate-enriched ground water were greater than background concentrations. The surficial aquifer system in the area of the landfill consists primarily of sand of moderate permeability, from land surface to a depth of about 68 feet deep, and consists of sand interbedded with sandstone and limestone of high permeability from a depth of about 68 feet to a depth of 200 feet. The potentiometric surface in the landfill is higher than that in adjacent areas to the east, indicating ground-water movement from the landfill toward a lake to the east. Steady-state simulation of ground-water flow was made using a telescoping-grid technique where a model covering a large area is used to determine boundaries and fluxes for a finer scale model. A regional flow model encompassing a 500-square mile area in southeastern Palm Beach County was used to calculate ground-water fluxes in a 126.5-square mile subregional area. Boundary fluxes calculated by the subregional model were then used to calculate boundary fluxes for a local model of the 3.75-square mile area representing the Lantana landfill site and vicinity. Input data required for simulating ground-water flow in the study area were obtained from the regional flow models, thus, effectively coupling the models. Additional simulations were made using the local flow model to predict effects of possible remedial actions on the movement of solutes in the ground-water system. Possible remedial actions simulated included capping the landfill with an impermeable layer

  5. Coupling a three-dimensional subsurface flow and transport model with a land surface model to simulate stream-aquifer-land interactions (CP v1.0)

    Science.gov (United States)

    Bisht, Gautam; Huang, Maoyi; Zhou, Tian; Chen, Xingyuan; Dai, Heng; Hammond, Glenn E.; Riley, William J.; Downs, Janelle L.; Liu, Ying; Zachara, John M.

    2017-12-01

    A fully coupled three-dimensional surface and subsurface land model is developed and applied to a site along the Columbia River to simulate three-way interactions among river water, groundwater, and land surface processes. The model features the coupling of the Community Land Model version 4.5 (CLM4.5) and a massively parallel multiphysics reactive transport model (PFLOTRAN). The coupled model, named CP v1.0, is applied to a 400 m × 400 m study domain instrumented with groundwater monitoring wells along the Columbia River shoreline. CP v1.0 simulations are performed at three spatial resolutions (i.e., 2, 10, and 20 m) over a 5-year period to evaluate the impact of hydroclimatic conditions and spatial resolution on simulated variables. Results show that the coupled model is capable of simulating groundwater-river-water interactions driven by river stage variability along managed river reaches, which are of global significance as a result of over 30 000 dams constructed worldwide during the past half-century. Our numerical experiments suggest that the land-surface energy partitioning is strongly modulated by groundwater-river-water interactions through expanding the periodically inundated fraction of the riparian zone, and enhancing moisture availability in the vadose zone via capillary rise in response to the river stage change. Meanwhile, CLM4.5 fails to capture the key hydrologic process (i.e., groundwater-river-water exchange) at the site, and consequently simulates drastically different water and energy budgets. Furthermore, spatial resolution is found to significantly impact the accuracy of estimated the mass exchange rates at the boundaries of the aquifer, and it becomes critical when surface and subsurface become more tightly coupled with groundwater table within 6 to 7 meters below the surface. Inclusion of lateral subsurface flow influenced both the surface energy budget and subsurface transport processes as a result of river-water intrusion into the

  6. Groundwater flow and radionuclide transport modelling using CONNECTFLOW in support of the SR Can assessment

    International Nuclear Information System (INIS)

    Hartley, Lee; Cox, Ian; Holton, David; Hunter, Fiona; Joyce, Steve; Gylling, Bjoern; Lindgren, Maria

    2004-09-01

    outputs from the modelling will be the groundwater flux, the definition of flow paths and values for parameters describing the transport of radionuclides along the paths. Ultimately, the results from the groundwater flow modelling will feed into biosphere calculations of radiological risks to man. SKB's methodology refers to three scales of modelling, these being Regional (∼10 km), local (∼1 km) and 'repository/block' (10-100 m). Using models at these scales it is necessary to simulate the transient, variable-density groundwater flow in sufficient detail to enable the groundwater flux and radionuclide transport paths to be determined. Research into ways of coupling the geosphere and biosphere through near-surface and surface hydrology models is ongoing within the SKB programme. The focus of the project reported here has been to illustrate and test the geosphere methodology for the post-closure phase of the safety assessment, that is, between the present and 10,000 years after present. In order to demonstrate the groundwater flow and transport methodology outlined by SKB in TR-03-08, a set of nested models has been constructed using Serco Assurance's CONNECTFLOW software in order to assess issues on various key scales. These nested models are: a regional-scale CPM model containing representations of deterministic large-scale fracture zones, with site-scale hydrogeological properties based on and consistent with an underlying DFN data description. The purpose of this model is to study transients and provide boundary conditions for models on smaller-scales; a local-scale DFN model nested within a regional-scale CPM model to assess far-field transport pathways, but also capture the detailed transport pathways through the DFN immediately around the repository tunnels; a CPM representation of the deposition holes, engineered damage zone (EDZ) and deposition tunnels nested within a canister-scale DFN model. This model is used to perform detailed calculations of groundwater

  7. Development of the Transport Class Model (TCM) Aircraft Simulation From a Sub-Scale Generic Transport Model (GTM) Simulation

    Science.gov (United States)

    Hueschen, Richard M.

    2011-01-01

    A six degree-of-freedom, flat-earth dynamics, non-linear, and non-proprietary aircraft simulation was developed that is representative of a generic mid-sized twin-jet transport aircraft. The simulation was developed from a non-proprietary, publicly available, subscale twin-jet transport aircraft simulation using scaling relationships and a modified aerodynamic database. The simulation has an extended aerodynamics database with aero data outside the normal transport-operating envelope (large angle-of-attack and sideslip values). The simulation has representative transport aircraft surface actuator models with variable rate-limits and generally fixed position limits. The simulation contains a generic 40,000 lb sea level thrust engine model. The engine model is a first order dynamic model with a variable time constant that changes according to simulation conditions. The simulation provides a means for interfacing a flight control system to use the simulation sensor variables and to command the surface actuators and throttle position of the engine model.

  8. The treatment of water-conducting features in groundwater flow and transport modelling of the Borrowdale Volcanic Group in Nirex 97

    International Nuclear Information System (INIS)

    Jackson, C.P.; Norris, S.; Todman, S.J.; Watson, S.P.

    1999-01-01

    In the Nirex 97 assessment of the post-closure performance of a repository at Sellafield, the potential repository host rock was the Borrowdale Volcanic Group (BVG). The treatment of water-conducting features in groundwater flow and transport modelling of the BVG is discussed. Groundwater flow in the BVG is predominantly through a subset of the total set of discontinuities - the Flowing Features (FFs). FFs can be identified in core samples by the presence of recent calcite. In boreholes, the FFs are clustered, and the clustering appears to be significant hydro-geologically. However, there is uncertainty about the connectivity of the clusters. A range of models is possible, from the case of isolated clusters to the case where the clusters form a well-connected network. The radiological risk from the repository was determined from radionuclide transport calculations based on the groundwater flow fields obtained from the regional-scale flow calculations. For rocks, such as the BVG, in which groundwater flows predominantly through discontinuities, diffusion into immobile water int the rock matrix between the discontinuities was modelled. Data from the site characterization and research programmes could be used to develop and parameterize groundwater flow and transport models for use in repository performance assessments. (author)

  9. Hybrid Multiscale Finite Volume method for multiresolution simulations of flow and reactive transport in porous media

    Science.gov (United States)

    Barajas-Solano, D. A.; Tartakovsky, A. M.

    2017-12-01

    We present a multiresolution method for the numerical simulation of flow and reactive transport in porous, heterogeneous media, based on the hybrid Multiscale Finite Volume (h-MsFV) algorithm. The h-MsFV algorithm allows us to couple high-resolution (fine scale) flow and transport models with lower resolution (coarse) models to locally refine both spatial resolution and transport models. The fine scale problem is decomposed into various "local'' problems solved independently in parallel and coordinated via a "global'' problem. This global problem is then coupled with the coarse model to strictly ensure domain-wide coarse-scale mass conservation. The proposed method provides an alternative to adaptive mesh refinement (AMR), due to its capacity to rapidly refine spatial resolution beyond what's possible with state-of-the-art AMR techniques, and the capability to locally swap transport models. We illustrate our method by applying it to groundwater flow and reactive transport of multiple species.

  10. Groundwater flow and tritium migration from the SRS Old Burial Ground to Fourmile Branch

    International Nuclear Information System (INIS)

    Flach, G.P.; Hamm, L.L.; Harris, M.K.

    1996-04-01

    The objectives of this investigation are twofold. The initial goal is to devise and demonstrate a technique for directly incorporating fine-scale lithologic data into heterogeneous hydraulic conductivity fields, for improved groundwater flow and contaminant transport model accuracy. The ultimate goal is to rigorously simulate past and future tritium migration from the SRS Old Burial Ground towards Fourmile Branch, to better understand the effects of various remediation alternatives such as no action and capping. Large-scale variability in hydraulic conductivity is usually the main influence on field-scale groundwater flow patterns and dispersive transport, following the relative locations of recharge and discharge areas. Incorporating realistic hydraulic conductivity heterogeneity into flow and transport models is paramount to accurate simulations, particularly for contaminant migration. Sediment lithologic descriptions and geophysical logs typically offer finer spatial resolution, and therefore more potential information about heterogeneity, than other site characterization data

  11. Micropollutants in groundwater from septic systems: Transformations, transport mechanisms, and human health risk assessment.

    Science.gov (United States)

    Yang, Yun-Ya; Toor, Gurpal S; Wilson, P Chris; Williams, Clinton F

    2017-10-15

    Septic systems may contribute micropollutants to shallow groundwater and surface water. We constructed two in situ conventional drainfields (drip dispersal and gravel trench) and an advanced drainfield of septic systems to investigate the fate and transport of micropollutants to shallow groundwater. Unsaturated soil-water and groundwater samples were collected, over 32 sampling events (January 2013 to June 2014), from the drainfields (0.31-1.07 m deep) and piezometers (3.1-3.4 m deep). In addition to soil-water and groundwater, effluent samples collected from the septic tank were also analyzed for 20 selected micropollutants, including wastewater markers, hormones, pharmaceuticals and personal care products (PPCPs), a plasticizer, and their transformation products. The removal efficiencies of micropollutants from septic tank effluent to groundwater were similar among three septic systems and were 51-89% for sucralose and 53->99% for other micropollutants. Even with high removal rates within the drainfields, six PPCPs and sucralose with concentrations ranging from septic systems to ecosystem and human health is warranted for the long-term sustainability of septic systems. Copyright © 2017 Elsevier Ltd. All rights reserved.

  12. Application of environmental isotopes to validate a model of regional groundwater flow and transport (Carrizo Aquifer)

    International Nuclear Information System (INIS)

    Pearson, F.J.

    1999-01-01

    It is asserted that models cannot be validated. This seems obvious if one identifies validation as the process of testing a model against absolute truth, and accepts that absolute truth is less a scientific than a philosophic or religious concept. What is here called model validation has a more modest goal - to develop confidence in the conceptual and mathematical models used to describe a groundwater system by illustrating that measured radiochemical properties of the groundwater match those predicted by the model. The system described is the Carrizo sand in the Gulf Coastal Plain of south Texas. Each element of the modelling chain describing the movement of 14 C is confirmed independently and, thus, can be said to be validated. The groundwater ages, and the 14 C measurements and carbonate geochemical model underlying them, are confirmed by the noble gas measurements, while the flow and transport model is confirmed by the 14 C results. Agreement between the modelled and measured 234 U/ 238 U ratios supports the description of U transport used in the modelling, while the need to use an unexpectedly low K D value for U raises questions about the applicability of laboratory K D data to the Carrizo groundwater system. (author)

  13. Leaching and soil/groundwater transport of contaminants from coal combustion residues

    International Nuclear Information System (INIS)

    Hjelmar, O.; Hansen, E.A.; Larsen, F.; Thomassen, H.

    1992-01-01

    In this project the results of accelerated laboratory leaching tests on coal fly ash and flue gas desulfurization (FGD) products from the spray dryer absorption process (SDA) were evaluated by comparison to the results of large scale lysimeter leaching tests on the same residues. The mobility of chromium and molybdenum - two of the kev contaminants of coal combustion residue leachates - in various typical soil types was investigated by batch and column methods in the laboratory. Some of the results were confirmed by field observations at an old coal fly ash disposal site and by a lysimeter attenuation test with coal fly ash leachate on a clayed till. A large number of groundwater transport models and geochemical models were reviewed, and two of the models (Gove-Stollenwerk and CHMTRNS) were modified and adjusted and used to simulate column attenuation tests performed in the laboratory. One of the models (Grove-Stollenwerk) was used to illustrate a recommended method of environmental impact assessment, using lysimeter leaching data and laboratory column attenuation data to describe the emission and migration of Mo from a coal fly ash disposal site

  14. Incorporation of sedimentological data into a calibrated groundwater flow and transport model

    International Nuclear Information System (INIS)

    Williams, N.J.; Young, S.C.; Barton, D.H.; Hurst, B.T.

    1997-01-01

    Analysis suggests that a high hydraulic conductivity (K) zone is associated with a former river channel at the Portsmouth Gaseous Diffusion Plant (PORTS). A two-dimensional (2-D) and three-dimensional (3-D) groundwater flow model was developed base on a sedimentological model to demonstrate the performance of a horizontal well for plume capture. The model produced a flow field with magnitudes and directions consistent with flow paths inferred from historical trichloroethylene (TCE) plume data. The most dominant feature affecting the well's performance was preferential high- and low-K zones. Based on results from the calibrated flow and transport model, a passive groundwater collection system was designed and built. Initial flow rates and concentrations measured from a gravity-drained horizontal well agree closely to predicted values

  15. Multi-Objective Optimization of an In situ Bioremediation Technology to Treat Perchlorate-Contaminated Groundwater

    Science.gov (United States)

    The presentation shows how a multi-objective optimization method is integrated into a transport simulator (MT3D) for estimating parameters and cost of in-situ bioremediation technology to treat perchlorate-contaminated groundwater.

  16. Reactive transport modelling of groundwater-bentonite interaction: Effects on exchangeable cations in an alternative buffer material in-situ test

    International Nuclear Information System (INIS)

    Wallis, I.; Idiart, A.; Dohrmann, R.; Post, V.

    2016-01-01

    Bentonite clays are regarded a promising material for engineered barrier systems for the encapsulation of hazardous wastes because of their low hydraulic permeability, swelling potential, ability to self-seal cracks in contact with water and their high sorption potential. SKB (Svensk Kärnbränslehantering) has been conducting long term field scale experiments on potential buffer materials at the Äspö Hard Rock Laboratory for radioactive waste disposal in Sweden. The Alternative Buffer Material (ABM) test examined buffer properties of eleven different clay materials under the influence of groundwater and at temperatures reaching up to 135 °C, replicating the heat pulse after waste emplacement. Clay materials were emplaced into holes drilled in fractured granite as compacted rings around a central heater element and subsequently brought into contact with groundwater for 880 days. After test termination, and against expectations, all clay materials were found to have undergone large scale alterations in the cation exchange population. A reactive-diffusive transport model was developed to aid the interpretation of the observed large-scale porewater chemistry changes. It was found, that the interaction between Äspö groundwater and the clay blocks, together with the geochemical nature of the clays (Na vs Ca-dominated clays) exerted the strongest control on the porewater chemistry. A pronounced exchange of Na by Ca was observed and simulated, driven by large Ca concentrations in the contacting groundwater. The model was able to link the porewater alterations to the fracture network in the deposition hole. The speed of alterations was in turn linked to high diffusion coefficients under the applied temperatures, which facilitated the propagation of hydrochemical changes into the clays. With diffusion coefficients increased by up to one order of magnitude at the maximum temperatures, the study was able to demonstrate the importance of considering temperature

  17. Model Simulations of a Field Experiment on Cation Exchange-affected Multicomponent Solute Transport in a Sandy Aquifer

    DEFF Research Database (Denmark)

    Bjerg, Poul Løgstrup; Ammentorp, Hans Christian; Christensen, Thomas Højlund

    1993-01-01

    A large-scale and long-term field experiment on cation exchange in a sandy aquifer has been modelled by a three-dimensional geochemical transport model. The geochemical model includes cation-exchange processes using a Gaines-Thomas expression, the closed carbonate system and the effects of ionic...... by batch experiments and by the composition of the cations on the exchange complex. Potassium showed a non-ideal exchange behaviour with K&z.sbnd;Ca selectivity coefficients indicating dependency on equivalent fraction and K+ concentration in the aqueous phase. The model simulations over a distance of 35 m...... and a period of 250 days described accurately the observed attenuation of Na and the expelled amounts of Ca and Mg. Also, model predictions of plateau zones, formed by interaction with the background groundwater, in general agreed satisfactorily with the observations. Transport of K was simulated over a period...

  18. Conservative Eulerian-Lagrangian Methods and Mixed Finite Element Methods for Modeling of Groundwater Flow and Transport

    National Research Council Canada - National Science Library

    Russell, Thomas

    2000-01-01

    New, improved computational methods for modeling of groundwater flow and transport have been formulated and implemented, with the intention of incorporating them as user options into the DoD Ground...

  19. Approaches to the simulation of unconfined flow and perched groundwater flow in MODFLOW

    Science.gov (United States)

    Bedekar, Vivek; Niswonger, Richard G.; Kipp, Kenneth; Panday, Sorab; Tonkin, Matthew

    2012-01-01

    Various approaches have been proposed to manage the nonlinearities associated with the unconfined flow equation and to simulate perched groundwater conditions using the MODFLOW family of codes. The approaches comprise a variety of numerical techniques to prevent dry cells from becoming inactive and to achieve a stable solution focused on formulations of the unconfined, partially-saturated, groundwater flow equation. Keeping dry cells active avoids a discontinuous head solution which in turn improves the effectiveness of parameter estimation software that relies on continuous derivatives. Most approaches implement an upstream weighting of intercell conductance and Newton-Raphson linearization to obtain robust convergence. In this study, several published approaches were implemented in a stepwise manner into MODFLOW for comparative analysis. First, a comparative analysis of the methods is presented using synthetic examples that create convergence issues or difficulty in handling perched conditions with the more common dry-cell simulation capabilities of MODFLOW. Next, a field-scale three-dimensional simulation is presented to examine the stability and performance of the discussed approaches in larger, practical, simulation settings.

  20. Regional groundwater flow in the Atikokan Research Area : simulation of 18O and 3H distributions

    International Nuclear Information System (INIS)

    Ophori, D.U.; Chan, Tin.

    1994-09-01

    AECL is investigating a concept for disposing of nuclear fuel waste deep in plutonic rock of the Canadian Shield. As part of this investigation, we have performed a model simulation of regional groundwater flow in the Atikokan Research Area, a fractured plutonic rock environment of the Canadian Shield, and used the distribution of oxygen-18 ( 18 O) and tritium ( 3 H) in groundwater to test the model. At the first stage of model calibration, groundwater flow was simulated using a three-dimensional finite-element code, MOTIF, in conjunction with a conceptual framework model derived from field geological, geophysical and hydrogeological data. Hydraulic parameters (permeability and porosity) were systematically varied until simulated recharge rates to the water table compared favourably with estimated recharge rates based on stream flow analysis. At the second stage, vertical average linear groundwater velocities from the first stage of the calibration process were combined with conceptualized one-dimensional models of the system to generate depth concentration profiles of 18 O and 3 H. Recharge-, midline-and discharge area models of both the fracture zones and the rock mass were employed. The simulated profiles formed 'envelopes' around all field 18 O and 3 H data, indicating that the calibrated velocities used in the model are reasonable. The models demonstrate that the scatter of δ 18 O and 3 H field data from the Atikokan Research Area is consistent with the groundwater flow model predictions and can be explained by the complexity arising from different hydraulic regimes (recharge, midline, discharge) and hydrogeologic environments (fracture zones, rock mass) of the regional flow system. 50 refs., 14 figs., 3 tabs

  1. Influence of faults on groundwater flow and transport at Yucca Mountain, Nevada

    International Nuclear Information System (INIS)

    Cohen, Andrew J.B.; Sitar, Nicholas

    1999-01-01

    Numerical simulations of groundwater flow at Yucca Mountain, Nevada are used to investigate how faults influence groundwater flow pathways and regional-scale macrodispersion. The 3-D model has a unique grid block discretization that facilitates the accurate representation of the complex geologic structure present in faulted formations. Each hydrogeologic layer is discretized into a single layer of irregular and dipping grid blocks, and faults are discretized such that they are laterally continuous and varied in displacement varies along strike. In addition, the presence of altered fault zones is explicitly modeled, as appropriate. Simulations show that upward head gradients can be readily explained by the geometry of hydrogeologic layers, the variability of layer permeabilities, and the presence of permeable fault zones or faults with displacement only, not necessarily by upwelling from a deep aquifer. Large-scale macrodispersion results from the vertical and lateral diversion of flow near the contact of high- and low-permeability layers at faults, and from upward flow within high-permeability fault zones. Conversely, large-scale channeling can occur as a result of groundwater flow into areas with minimal fault displacement. Contaminants originating at the water table can flow in a direction significantly different from that of the water table gradient, and isolated zones of contaminants can occur at the water table downgradient. By conducting both 2-D and 3-D simulations, we show that the 2-D cross-sectional models traditionally used to examine flow in faulted formations may not be appropriate. In addition, the influence of a particular type of fault cannot be generalized; depending on the location where contaminants enter the saturated zone, faults may either enhance or inhibit vertical dispersion

  2. Comparison of a Conceptual Groundwater Model and Physically Based Groundwater Mode

    Science.gov (United States)

    Yang, J.; Zammit, C.; Griffiths, J.; Moore, C.; Woods, R. A.

    2017-12-01

    Groundwater is a vital resource for human activities including agricultural practice and urban water demand. Hydrologic modelling is an important way to study groundwater recharge, movement and discharge, and its response to both human activity and climate change. To understand the groundwater hydrologic processes nationally in New Zealand, we have developed a conceptually based groundwater flow model, which is fully integrated into a national surface-water model (TopNet), and able to simulate groundwater recharge, movement, and interaction with surface water. To demonstrate the capability of this groundwater model (TopNet-GW), we applied the model to an irrigated area with water shortage and pollution problems in the upper Ruamahanga catchment in Great Wellington Region, New Zealand, and compared its performance with a physically-based groundwater model (MODFLOW). The comparison includes river flow at flow gauging sites, and interaction between groundwater and river. Results showed that the TopNet-GW produced similar flow and groundwater interaction patterns as the MODFLOW model, but took less computation time. This shows the conceptually-based groundwater model has the potential to simulate national groundwater process, and could be used as a surrogate for the more physically based model.

  3. MODLP program description: A program for solving linear optimal hydraulic control of groundwater contamination based on MODFLOW simulation. Version 1.0

    International Nuclear Information System (INIS)

    Ahlfeld, D.P.; Dougherty, D.E.

    1994-11-01

    MODLP is a computational tool that may help design capture zones for controlling the movement of contaminated groundwater. It creates and solves linear optimization programs that contain constraints on hydraulic head or head differences in a groundwater system. The groundwater domain is represented by USGS MODFLOW groundwater flow simulation model. This document describes the general structure of the computer program, MODLP, the types of constraints that may be imposed, detailed input instructions, interpretation of the output, and the interaction with the MODFLOW simulation kernel

  4. Simulation of climate change effects on streamflow, groundwater, and stream temperature using GSFLOW and SNTEMP in the Black Earth Creek Watershed, Wisconsin

    Science.gov (United States)

    Hunt, Randall J.; Westenbroek, Stephen M.; Walker, John F.; Selbig, William R.; Regan, R. Steven; Leaf, Andrew T.; Saad, David A.

    2016-08-23

    A groundwater/surface-water model was constructed and calibrated for the Black Earth Creek watershed in south-central Wisconsin. The model was then run to simulate scenarios representing common societal concerns in the basin, focusing on maintaining a cold-water resource in an urbanizing fringe near its upper stream reaches and minimizing downstream flooding. Although groundwater and surface water are considered a single resource, many hydrologic models simplistically simulate feedback loops between the groundwater system and other hydrologic processes. These feedbacks include timing and rates of evapotranspiration, surface runoff, soil-zone flow, and interactions with the groundwater system; however, computer models can now routinely and iteratively couple the surface-water and groundwater systems—albeit with longer model run times. In this study, preliminary calibrations of uncoupled transient surface-water and steady-state groundwater models were used to form the starting point for final calibration of one transient computer simulation that iteratively couples groundwater and surface water. The computer code GSFLOW (Groundwater/Surface-water FLOW) was used to simulate the coupled hydrologic system; a surface-water model represented hydrologic processes in the atmosphere, at land surface, and within the soil zone, and a groundwater-flow model represented the unsaturated zone, saturated zone, and streams. The coupled GSFLOW model was run on a daily time step during water years 1985–2007. Early simulation times (1985–2000) were used for spin-up to make the simulation results less sensitive to initial conditions specified; the spin-up period was not included in the model calibration. Model calibration used observed heads, streamflows, solar radiation, and snowpack measurements from 2000 to 2007 for history matching. Calibration was performed by using the PEST parameter estimation software suite.

  5. Simulation of Groundwater-Level and Salinity Changes in the Eastern Shore, Virginia

    Science.gov (United States)

    Sanford, Ward E.; Pope, Jason P.; Nelms, David L.

    2009-01-01

    Groundwater-level and salinity changes have been simulated with a groundwater model developed and calibrated for the Eastern Shore of Virginia. The Eastern Shore is the southern part of the Delmarva Peninsula that is occupied by Accomack and Northampton Counties in Virginia. Groundwater is the sole source of freshwater to the Eastern Shore, and demands for water have been increasing from domestic, industrial, agricultural, and public-supply sectors of the economy. Thus, it is important that the groundwater supply be protected from overextraction and seawater intrusion. The best way for water managers to use all of the information available is usually to compile this information into a numerical model that can simulate the response of the system to current and future stresses. A detailed description of the geology, hydrogeology, and historical groundwater extractions was compiled and entered into the numerical model. The hydrogeologic framework is composed of a surficial aquifer under unconfined conditions, a set of three aquifers and associated overlying confining units under confined conditions (the upper, middle, and lower Yorktown-Eastover Formation), and an underlying confining unit (the St. Marys Formation). An estimate of the location and depths of two major paleochannels was also included in the framework of the model. Total withdrawals from industrial, commercial, public-supply, and some agricultural wells were compiled from the period 1900 through 2003. Reported pumpage from these sources increased dramatically during the 1960s and 70s, up to currently about 4 million gallons per day. Domestic withdrawals were estimated on the basis of population census districts and were assigned spatially to the model on the assumption that domestic users are located close to roads. A numerical model was created using the U.S. Geological Survey (USGS) code SEAWAT to simulate both water levels and concentrations of chloride (representing salinity). The model was

  6. A Review of Distributed Parameter Groundwater Management Modeling Methods

    Science.gov (United States)

    Gorelick, Steven M.

    1983-04-01

    Models which solve the governing groundwater flow or solute transport equations in conjunction with optimization techniques, such as linear and quadratic programing, are powerful aquifer management tools. Groundwater management models fall in two general categories: hydraulics or policy evaluation and water allocation. Groundwater hydraulic management models enable the determination of optimal locations and pumping rates of numerous wells under a variety of restrictions placed upon local drawdown, hydraulic gradients, and water production targets. Groundwater policy evaluation and allocation models can be used to study the influence upon regional groundwater use of institutional policies such as taxes and quotas. Furthermore, fairly complex groundwater-surface water allocation problems can be handled using system decomposition and multilevel optimization. Experience from the few real world applications of groundwater optimization-management techniques is summarized. Classified separately are methods for groundwater quality management aimed at optimal waste disposal in the subsurface. This classification is composed of steady state and transient management models that determine disposal patterns in such a way that water quality is protected at supply locations. Classes of research missing from the literature are groundwater quality management models involving nonlinear constraints, models which join groundwater hydraulic and quality simulations with political-economic management considerations, and management models that include parameter uncertainty.

  7. Hydrogeology and simulation of groundwater flow in the Central Oklahoma (Garber-Wellington) Aquifer, Oklahoma, 1987 to 2009, and simulation of available water in storage, 2010–2059

    Science.gov (United States)

    Mashburn, Shana L.; Ryter, Derek W.; Neel, Christopher R.; Smith, S. Jerrod; Magers, Jessica S.

    2014-02-10

    The Central Oklahoma (Garber-Wellington) aquifer underlies about 3,000 square miles of central Oklahoma. The study area for this investigation was the extent of the Central Oklahoma aquifer. Water from the Central Oklahoma aquifer is used for public, industrial, commercial, agricultural, and domestic supply. With the exception of Oklahoma City, all of the major communities in central Oklahoma rely either solely or partly on groundwater from this aquifer. The Oklahoma City metropolitan area, incorporating parts of Canadian, Cleveland, Grady, Lincoln, Logan, McClain, and Oklahoma Counties, has a population of approximately 1.2 million people. As areas are developed for groundwater supply, increased groundwater withdrawals may result in decreases in long-term aquifer storage. The U.S. Geological Survey, in cooperation with the Oklahoma Water Resources Board, investigated the hydrogeology and simulated groundwater flow in the aquifer using a numerical groundwater-flow model. The purpose of this report is to describe an investigation of the Central Oklahoma aquifer that included analyses of the hydrogeology, hydrogeologic framework of the aquifer, and construction of a numerical groundwater-flow model. The groundwater-flow model was used to simulate groundwater levels and for water-budget analysis. A calibrated transient model was used to evaluate changes in groundwater storage associated with increased future water demands.

  8. Numerical simulation of groundwater and surface-water interactions in the Big River Management Area, central Rhode Island

    Science.gov (United States)

    Masterson, John P.; Granato, Gregory E.

    2013-01-01

    The Rhode Island Water Resources Board is considering use of groundwater resources from the Big River Management Area in central Rhode Island because increasing water demands in Rhode Island may exceed the capacity of current sources. Previous water-resources investigations in this glacially derived, valley-fill aquifer system have focused primarily on the effects of potential groundwater-pumping scenarios on streamflow depletion; however, the effects of groundwater withdrawals on wetlands have not been assessed, and such assessments are a requirement of the State’s permitting process to develop a water supply in this area. A need for an assessment of the potential effects of pumping on wetlands in the Big River Management Area led to a cooperative agreement in 2008 between the Rhode Island Water Resources Board, the U.S. Geological Survey, and the University of Rhode Island. This partnership was formed with the goal of developing methods for characterizing wetland vegetation, soil type, and hydrologic conditions, and monitoring and modeling water levels for pre- and post-water-supply development to assess potential effects of groundwater withdrawals on wetlands. This report describes the hydrogeology of the area and the numerical simulations that were used to analyze the interaction between groundwater and surface water in response to simulated groundwater withdrawals. The results of this analysis suggest that, given the hydrogeologic conditions in the Big River Management Area, a standard 5-day aquifer test may not be sufficient to determine the effects of pumping on water levels in nearby wetlands. Model simulations showed water levels beneath Reynolds Swamp declined by about 0.1 foot after 5 days of continuous pumping, but continued to decline by an additional 4 to 6 feet as pumping times were increased from a 5-day simulation period to a simulation period representative of long-term average monthly conditions. This continued decline in water levels with

  9. Application of mathematical model for simulation of groundwater flow

    International Nuclear Information System (INIS)

    Carvalho Filho, Carlos Alberto de; Branco, Otavio Eurico de Aquino; Loureiro, Celso de Oliveira

    2000-01-01

    The main purpose of the present research work is the groundwater flow characterization of the aquifer system of the Engenho Nogueira Creek watershed basin, particularly within the limits of the Pampulha Campus of the Federal University of Minas Gerais and nearby. In order to reach the aforementioned goal, a numerical model was implemented for simulation the groundwater flow, using the MODFLOW code. The local hydrogeology consists of a porous granular aquifer placed above and hydraulically connected to a fractured aquifer, constituting a unique aquifer system, mixed and phreatic type, heterogeneous and anisotropic. The local hydrogeological system is strongly influenced by a complex drain system and by the Engenho Nogueira Creek. After calibration, it was possible to predict the average phreatic depth measured in the observation wells for the period in study with a standard deviation of 1.65 m and a correlation coefficient of 0.94. (author)

  10. Development, Testing, and Application of a Coupled Hydrodynamic Surface-Water/Groundwater Model (FTLOADDS) with Heat and Salinity Transport in the Ten Thousand Islands/Picayune Strand Restoration Project Area, Florida

    Science.gov (United States)

    Swain, Eric D.; Decker, Jeremy D.

    2009-01-01

    A numerical model application was developed for the coastal area inland of the Ten Thousand Islands (TTI) in southwestern Florida using the Flow and Transport in a Linked Overland/Aquifer Density-Dependent System (FTLOADDS) model. This model couples a two-dimensional dynamic surface-water model with a three-dimensional groundwater model, and has been applied to several locations in southern Florida. The model application solves equations for salt transport in groundwater and surface water, and also simulates surface-water temperature using a newly enhanced heat transport algorithm. One of the purposes of the TTI application is to simulate hydrologic factors that relate to habitat suitability for the West Indian Manatee. Both salinity and temperature have been shown to be important factors for manatee survival. The inland area of the TTI domain is the location of the Picayune Strand Restoration Project, which is designed to restore predevelopment hydrology through the filling and plugging of canals, construction of spreader channels, and the construction of levees and pump stations. The effects of these changes are simulated to determine their effects on manatee habitat. The TTI application utilizes a large amount of input data for both surface-water and groundwater flow simulations. These data include topography, frictional resistance, atmospheric data including rainfall and air temperature, aquifer properties, and boundary conditions for tidal levels, inflows, groundwater heads, and salinities. Calibration was achieved by adjusting the parameters having the largest uncertainty: surface-water inflows, the surface-water transport dispersion coefficient, and evapotranspiration. A sensitivity analysis did not indicate that further parameter changes would yield an overall improvement in simulation results. The agreement between field data from GPS-tracked manatees and TTI application results demonstrates that the model can predict the salinity and temperature

  11. Approach to uncertainty assessment for fluid flow and contaminant transport modeling in heterogeneous groundwater systems

    International Nuclear Information System (INIS)

    Nelson, R.W.; Jacobson, E.A.; Conbere, W.

    1985-06-01

    There is a growing awareness of the need to quantify uncertainty in groundwater flow and transport model results. Regulatory organizations are beginning to request the statistical distributions of predicted contaminant arrival to the biosphere, so that realistic confidence intervals can be obtained for the modeling results. To meet these needs, methods are being developed to quantify uncertainty in the subsurface flow and transport analysis sequence. A method for evaluating this uncertainty, described in this paper, considers uncertainty in material properties and was applied to an example field problem. Our analysis begins by using field measurements of transmissivity and hydraulic head in a regional, parameter estimation method to obtain a calibrated fluid flow model and a covariance matrix of the parameter estimation errors. The calibrated model and the covariance matrix are next used in a conditional simulation mode to generate a large number of 'head realizations.' The specific pore water velocity distribution for each realization is calculated from the effective porosity, the aquifer parameter realization, and the associated head values. Each velocity distribution is used to obtain a transport solution for a contaminant originating from the same source for all realizations. The results are the statistical distributions for the outflow arrival times. The confidence intervals for contamination reaching the biosphere are obtained from the outflow statistical distributions. 20 refs., 12 figs

  12. Development and applications of two finite element groundwater flow and contaminant transport models: FEWA and FEMA

    International Nuclear Information System (INIS)

    Yeh, G.T.; Wong, K.V.; Craig, P.M.; Davis, E.C.

    1985-01-01

    This paper presents the construction, verification, and application of two groundwater flow and contaminant transport models: A Finite Element Model of Water Flow through Aquifers (FEWA) and A Finite Element Model of Material Transport through Aquifers (FEMA). The construction is based on the finite element approximation of partial differential equations of groundwater flow (FEWA) and of solute movement (FEMA). The particular features of FEWA and FEMA are their versatility and flexibility for dealing with nearly all vertically integrated two-dimensional problems. The models were verified against both analytical solutions and widely used US Geological Survey finite difference approximations. They were then applied for calibration and validation, using data obtained in experiments at the Engineering Test Facility at Oak Ridge National Laboratory. Results indicated that the models are valid for this specific site. To demonstrate the versatility anf flexibility of the models, they were applied to two hypothetical, but realistic, complex problems and three field sites across the United States. In these applications the models yielded good agreement with the field data for all three sites. Finally, the predictive capabilities of the models were demonstrated using data obtained at the Hialeah Preston site in Florida. This case illustrates the capability of FEWA and FEMA as predictive tools and their usefulness in the management of groundwater flow and contaminant transport. 25 refs

  13. SCATTER: Source and Transport of Emplaced Radionuclides: Code documentation

    International Nuclear Information System (INIS)

    Longsine, D.E.

    1987-03-01

    SCATTER simulated several processes leading to the release of radionuclides to the site subsystem and then simulates transport via the groundwater of the released radionuclides to the biosphere. The processes accounted for to quantify release rates to a ground-water migration path include radioactive decay and production, leaching, solubilities, and the mixing of particles with incoming uncontaminated fluid. Several decay chains of arbitrary length can be considered simultaneously. The release rates then serve as source rates to a numerical technique which solves convective-dispersive transport for each decay chain. The decay chains are allowed to have branches and each member can have a different radioactive factor. Results are cast as radionuclide discharge rates to the accessible environment

  14. Reactive dispersive contaminant transport in coastal aquifers: Numerical simulation of a reactive Henry problem

    KAUST Repository

    Nick, H.M.

    2013-02-01

    The reactive mixing between seawater and terrestrial water in coastal aquifers influences the water quality of submarine groundwater discharge. While these waters come into contact at the seawater groundwater interface by density driven flow, their chemical components dilute and react through dispersion. A larger interface and wider mixing zone may provide favorable conditions for the natural attenuation of contaminant plumes. It has been claimed that the extent of this mixing is controlled by both, porous media properties and flow conditions. In this study, the interplay between dispersion and reactive processes in coastal aquifers is investigated by means of numerical experiments. Particularly, the impact of dispersion coefficients, the velocity field induced by density driven flow and chemical component reactivities on reactive transport in such aquifers is studied. To do this, a hybrid finite-element finite-volume method and a reactive simulator are coupled, and model accuracy and applicability are assessed. A simple redox reaction is considered to describe the degradation of a contaminant which requires mixing of the contaminated groundwater and the seawater containing the terminal electron acceptor. The resulting degradation is observed for different scenarios considering different magnitudes of dispersion and chemical reactivity. Three reactive transport regimes are found: reaction controlled, reaction-dispersion controlled and dispersion controlled. Computational results suggest that the chemical components\\' reactivity as well as dispersion coefficients play a significant role on controlling reactive mixing zones and extent of contaminant removal in coastal aquifers. Further, our results confirm that the dilution index is a better alternative to the second central spatial moment of a plume to describe the mixing of reactive solutes in coastal aquifers. © 2012 Elsevier B.V.

  15. Application of a soil and ground-water pollutant-transport model

    International Nuclear Information System (INIS)

    Reeves, M.; Duguid, J.O.

    1975-01-01

    A general two-dimensional model was developed for simulation of saturated-unsaturated transport of radionuclides in ground water. This model is being applied to the transport of radionuclides from waste-disposal sites, where field investigations are currently under way to obtain the necessary parameters. A zero-order simulation of a waste-disposal trench is presented. Estimated values of the soil properties have been used since very limited experimental information is available at the present time. However, as more measured values become available from field studies, the simulation will be updated. The end product of this research will be a reliable computer model useful both in predicting future transport of radionuclides from buried waste and in examining control measures if they are shown to be necessary. (U.S.)

  16. Studies Related to the Role of Colloids on the Transport of Some Radio Contaminants in Groundwater

    International Nuclear Information System (INIS)

    Mekhemar, H.S.A.

    2012-01-01

    The safety of a radioactive waste repository is related to its capacity to confine radioactivity and isolate it from biosphere. The most likely process that can lead to the release of radionuclides from a repository to the geosphere is transport by groundwater. The transport and distribution of radionuclides in groundwater or through geologic media depend on the radioactive source, the physicochemical forms of radionuclides and interactions of radionuclides with other components present in the groundwater. Colloids naturally exist in groundwater aquifers and can significantly impact contaminant migration rate. The presence of colloids affects contaminant transport in aquifers either by facilitation or retardation. The effect of the presence of colloid (Al 2 O 3 ) on the sorption characteristics of Co 2+ and Cs + , as two of the most important radionuclides commonly encountered in the Egyptian waste streams, onto yellow sand and clay taken from Inshas site was studied. Based on the obtained results, the maximum sorption capacity of Cs + and Co 2+ in presence of colloid was higher than sorption in absence of colloid but the sorption capacity of clay was found to be greater than that of yellow sand for both ions in absence and presence of colloid. Sorption capacity (q) increased by increasing initial metal ion concentration. The increasing temperature from 25 to 65 degree C leads to slight decrease in the sorption of Cs ions while lead to increase in sorption of Co ions. The kinetic data could be successfully interpreted by simplified second order kinetic expression. The rate constants and the theoretical equilibrium Sorption capacities were calculated for studied cases. It was demonstrated from column experiments that colloid presence influences radionuclides transport through fixed bed yellow sand column. Al 2 O 3 and Fe 2 O 3 colloids reduce the migration of Cs + and Co 2+ ions in all studied cases. From the results of desorption experiments it can be concluded

  17. On the combination of isotope hydrogeology with regional flow and transport modelling

    International Nuclear Information System (INIS)

    Barmen, G.A.

    1992-01-01

    Many different methods and tools can be used when trying to improve the information basis on which decisions are made for maintaining a quantitatively and qualitatively safe, long-term use of groundwater resources. In this thesis, classical hydrogeological examinations, hydrochemical investigations, environmental isotope studies, computerized groundwater flow modelling and radioisotope transport modelling have been applied to the large system of reservoirs in the sedimentary deposits of southwestern Scania, Sweden. The stable isotopes 2 H, 18 O and 13 C and the radioactive 3 H and 14 C have been measured and the results obtained can improve the estimations of the periods of recharge and the average circulation times of the groundwater reservoirs studied. A groundwater flow model based on finite difference techniques and a continuum approach has been modified by data from traditional hydrogeological studies. The computer code, NEWSAM, has been used to simulate steady-state and transient isotope transport in the area studied, taking into account advective transport with radioactive decay. The interacting groundwater resevoirs studied have been represented by a three-dimensional system of grids in the numerical model. A major merit of this combination of isotope hydrogeology and regional flow and transport modelling is that the isotope transport simulations help to demonstrate where zones particularly vulnerable to pollution are situated. These locations are chiefly the results of the hydrogeological characteristics traditionally examined, but they are revealed by means of the transport model. Subsequent, more detailed investigations can then be focussed primarily on these vulnerable zones. High contents of radioisotopes in the main aquifer of southwestern Scania may indicate that groundwater withdrawals have stimulated recharge from shallow aquifers and surface waters and that the risk of pollution has increased. (196 refs.) (au)

  18. Assessing groundwater policy with coupled economic-groundwater hydrologic modeling

    Science.gov (United States)

    Mulligan, Kevin B.; Brown, Casey; Yang, Yi-Chen E.; Ahlfeld, David P.

    2014-03-01

    This study explores groundwater management policies and the effect of modeling assumptions on the projected performance of those policies. The study compares an optimal economic allocation for groundwater use subject to streamflow constraints, achieved by a central planner with perfect foresight, with a uniform tax on groundwater use and a uniform quota on groundwater use. The policies are compared with two modeling approaches, the Optimal Control Model (OCM) and the Multi-Agent System Simulation (MASS). The economic decision models are coupled with a physically based representation of the aquifer using a calibrated MODFLOW groundwater model. The results indicate that uniformly applied policies perform poorly when simulated with more realistic, heterogeneous, myopic, and self-interested agents. In particular, the effects of the physical heterogeneity of the basin and the agents undercut the perceived benefits of policy instruments assessed with simple, single-cell groundwater modeling. This study demonstrates the results of coupling realistic hydrogeology and human behavior models to assess groundwater management policies. The Republican River Basin, which overlies a portion of the Ogallala aquifer in the High Plains of the United States, is used as a case study for this analysis.

  19. Particle-transport simulation with the Monte Carlo method

    International Nuclear Information System (INIS)

    Carter, L.L.; Cashwell, E.D.

    1975-01-01

    Attention is focused on the application of the Monte Carlo method to particle transport problems, with emphasis on neutron and photon transport. Topics covered include sampling methods, mathematical prescriptions for simulating particle transport, mechanics of simulating particle transport, neutron transport, and photon transport. A literature survey of 204 references is included. (GMT)

  20. Review: Optimization methods for groundwater modeling and management

    Science.gov (United States)

    Yeh, William W.-G.

    2015-09-01

    Optimization methods have been used in groundwater modeling as well as for the planning and management of groundwater systems. This paper reviews and evaluates the various optimization methods that have been used for solving the inverse problem of parameter identification (estimation), experimental design, and groundwater planning and management. Various model selection criteria are discussed, as well as criteria used for model discrimination. The inverse problem of parameter identification concerns the optimal determination of model parameters using water-level observations. In general, the optimal experimental design seeks to find sampling strategies for the purpose of estimating the unknown model parameters. A typical objective of optimal conjunctive-use planning of surface water and groundwater is to minimize the operational costs of meeting water demand. The optimization methods include mathematical programming techniques such as linear programming, quadratic programming, dynamic programming, stochastic programming, nonlinear programming, and the global search algorithms such as genetic algorithms, simulated annealing, and tabu search. Emphasis is placed on groundwater flow problems as opposed to contaminant transport problems. A typical two-dimensional groundwater flow problem is used to explain the basic formulations and algorithms that have been used to solve the formulated optimization problems.

  1. MODFLOW-2000, the U.S. Geological Survey Modular Ground-Water Model--Documentation of the SEAWAT-2000 Version with the Variable-Density Flow Process (VDF) and the Integrated MT3DMS Transport Process (IMT)

    Science.gov (United States)

    Langevin, Christian D.; Shoemaker, W. Barclay; Guo, Weixing

    2003-01-01

    SEAWAT-2000 is the latest release of the SEAWAT computer program for simulation of three-dimensional, variable-density, transient ground-water flow in porous media. SEAWAT-2000 was designed by combining a modified version of MODFLOW-2000 and MT3DMS into a single computer program. The code was developed using the MODFLOW-2000 concept of a process, which is defined as ?part of the code that solves a fundamental equation by a specified numerical method.? SEAWAT-2000 contains all of the processes distributed with MODFLOW-2000 and also includes the Variable-Density Flow Process (as an alternative to the constant-density Ground-Water Flow Process) and the Integrated MT3DMS Transport Process. Processes may be active or inactive, depending on simulation objectives; however, not all processes are compatible. For example, the Sensitivity and Parameter Estimation Processes are not compatible with the Variable-Density Flow and Integrated MT3DMS Transport Processes. The SEAWAT-2000 computer code was tested with the common variable-density benchmark problems and also with problems representing evaporation from a salt lake and rotation of immiscible fluids.

  2. Quantification of anthropogenic impact on groundwater-dependent terrestrial ecosystem using geochemical and isotope tools combined with 3-D flow and transport modelling

    Science.gov (United States)

    Zurek, A. J.; Witczak, S.; Dulinski, M.; Wachniew, P.; Rozanski, K.; Kania, J.; Postawa, A.; Karczewski, J.; Moscicki, W. J.

    2015-02-01

    Groundwater-dependent ecosystems (GDEs) have important functions in all climatic zones as they contribute to biological and landscape diversity and provide important economic and social services. Steadily growing anthropogenic pressure on groundwater resources creates a conflict situation between nature and man which are competing for clean and safe sources of water. Such conflicts are particularly noticeable in GDEs located in densely populated regions. A dedicated study was launched in 2010 with the main aim to better understand the functioning of a groundwater-dependent terrestrial ecosystem (GDTE) located in southern Poland. The GDTE consists of a valuable forest stand (Niepolomice Forest) and associated wetland (Wielkie Błoto fen). It relies mostly on groundwater from the shallow Quaternary aquifer and possibly from the deeper Neogene (Bogucice Sands) aquifer. In July 2009 a cluster of new pumping wells abstracting water from the Neogene aquifer was set up 1 km to the northern border of the fen. A conceptual model of the Wielkie Błoto fen area for the natural, pre-exploitation state and for the envisaged future status resulting from intense abstraction of groundwater through the new well field was developed. The main aim of the reported study was to probe the validity of the conceptual model and to quantify the expected anthropogenic impact on the studied GDTE. A wide range of research tools was used. The results obtained through combined geologic, geophysical, geochemical, hydrometric and isotope investigations provide strong evidence for the existence of upward seepage of groundwater from the deeper Neogene aquifer to the shallow Quaternary aquifer supporting the studied GDTE. Simulations of the groundwater flow field in the study area with the aid of a 3-D flow and transport model developed for Bogucice Sands (Neogene) aquifer and calibrated using environmental tracer data and observations of hydraulic head in three different locations on the study area

  3. Predicting redox conditions in groundwater at a regional scale

    Science.gov (United States)

    Tesoriero, Anthony J.; Terziotti, Silvia; Abrams, Daniel B.

    2015-01-01

    Defining the oxic-suboxic interface is often critical for determining pathways for nitrate transport in groundwater and to streams at the local scale. Defining this interface on a regional scale is complicated by the spatial variability of reaction rates. The probability of oxic groundwater in the Chesapeake Bay watershed was predicted by relating dissolved O2 concentrations in groundwater samples to indicators of residence time and/or electron donor availability using logistic regression. Variables that describe surficial geology, position in the flow system, and soil drainage were important predictors of oxic water. The probability of encountering oxic groundwater at a 30 m depth and the depth to the bottom of the oxic layer were predicted for the Chesapeake Bay watershed. The influence of depth to the bottom of the oxic layer on stream nitrate concentrations and time lags (i.e., time period between land application of nitrogen and its effect on streams) are illustrated using model simulations for hypothetical basins. Regional maps of the probability of oxic groundwater should prove useful as indicators of groundwater susceptibility and stream susceptibility to contaminant sources derived from groundwater.

  4. Preliminary simulation of degassing of natural gases dissolved in groundwater during shaft excavation in Horonobe underground research project

    International Nuclear Information System (INIS)

    Yamamoto, Hajime; Shimo, Michito; Kunimaru, Takanori; Kurikami, Hiroshi

    2007-01-01

    In Neogene-Quaternary sedimentary basins, natural gases such as methane are often dissolved in groundwater significantly. In this paper, two-phase flow simulations incorporating the degassing of methane, and carbon dioxide, were performed for the shaft excavation in Horonobe underground research project. The results drawn from the simulations are summarized as follows. 1) As depth increases, degassing and gas inflow occurs significantly. 2) Degassing increases the compressibility of pore fluids, resulting in slow changes in groundwater pressures. 3) Although the occurrence of gas phase decreases water mobility, the influence of the dissolved gas on the groundwater inflow rate to the shaft was small. (author)

  5. Modeling hydrology, groundwater recharge and non-point nitrate loadings in the Himalayan Upper Yamuna basin.

    Science.gov (United States)

    Narula, Kapil K; Gosain, A K

    2013-12-01

    The mountainous Himalayan watersheds are important hydrologic systems responsible for much of the water supply in the Indian sub-continent. These watersheds are increasingly facing anthropogenic and climate-related pressures that impact spatial and temporal distribution of water availability. This study evaluates temporal and spatial distribution of water availability including groundwater recharge and quality (non-point nitrate loadings) for a Himalayan watershed, namely, the Upper Yamuna watershed (part of the Ganga River basin). The watershed has an area of 11,600 km(2) with elevation ranging from 6300 to 600 m above mean sea level. Soil and Water Assessment Tool (SWAT), a physically-based, time-continuous model, has been used to simulate the land phase of the hydrological cycle, to obtain streamflows, groundwater recharge, and nitrate (NO3) load distributions in various components of runoff. The hydrological SWAT model is integrated with the MODular finite difference groundwater FLOW model (MODFLOW), and Modular 3-Dimensional Multi-Species Transport model (MT3DMS), to obtain groundwater flow and NO3 transport. Validation of various modules of this integrated model has been done for sub-basins of the Upper Yamuna watershed. Results on surface runoff and groundwater levels obtained as outputs from simulation show a good comparison with the observed streamflows and groundwater levels (Nash-Sutcliffe and R(2) correlations greater than +0.7). Nitrate loading obtained after nitrification, denitrification, and NO3 removal from unsaturated and shallow aquifer zones is combined with groundwater recharge. Results for nitrate modeling in groundwater aquifers are compared with observed NO3 concentration and are found to be in good agreement. The study further evaluates the sensitivity of water availability to climate change. Simulations have been made with the weather inputs of climate change scenarios of A2, B2, and A1B for end of the century. Water yield estimates under

  6. Environmental Sciences Division Groundwater Program Office report for fiscal years 1995-1997

    International Nuclear Information System (INIS)

    Huff, D.D.

    1998-03-01

    The purpose of this report is to summarize the activities of the Groundwater Program Office in fiscal years 1995--1997 and document technical results achieved. One of the first contributions of the project was development and publication of a conceptual hydrologic framework for the Oak Ridge Reservation. This framework then served to guide research to fill important gaps in knowledge and suggest the most cost-effective approaches to site characterization and remediation. Examples of major goals include: quantitative characterization of the role of matrix diffusion in slowing transport of contaminants and impacting the practicality of pump and treat options for aquifer restoration; the importance of geologic structure and preferred flow pathways in the near surface zone (including the role of stormflow); evaluation of the importance of the deep groundwater system in contaminant migration; and acquisition of three-dimensional groundwater flow and contaminant transport simulation capability for fractured porous media

  7. Numerical simulation of pollutant transport in fractured vuggy porous karstic aquifers

    KAUST Repository

    Sun, S.; Fan, X.; Wei, W.; Kou, J.

    2011-01-01

    distribution of the vugs and the fractures impacts on the contaminant transport and the effluent concentration on the outlet. This paper sheds light on certain features of karstic groundwater are obtained.

  8. PATTERNS UTILIZED IN THE SIMULATION OF UNDERGROUND WATER FLOW AND THE TRANSPORTATION OF POLLUTANTS IN THE BAHLUI DRAINAGE BASIN

    Directory of Open Access Journals (Sweden)

    Ionut Minea

    2012-03-01

    Full Text Available ABSTRACT. – Patterns utilized in the simulation of underground water flow and the transportation of pollutants in the Bahlui drainage basin. In the actual context of accelerate economic development, the excessive exploatation of water resources from the underground and the contamination of these with different water pollutants has become a major problem which has enetered the attention of many researchers. For the evaluation of an underground water flow and pollutants transport sistem we have chosen the package of programs MODFLOW which includes a whole series of applications,such as MOC3D, MT3D, MT3DMS, PEST, UCODE, PMPATH, which allow simulations and multiple recalibrations of the capacity of recharging of the aquifers, the flowing of the water towards wells and drillings the transport of a pollutant agent in the underground or the evaluation of the exchange of water between the hidrographic network and aquifers. The sistem targets both the evaluation of the modelation of the underground flowing and the simulation of a punctual polluation of the canvas of groundwater scenery, in the meadow of the river Bahlui, west from Letcani village.

  9. Conceptual and numerical models of groundwater flow and solute transport in fracture zones: Application to the Aspo Island (Sweden)

    International Nuclear Information System (INIS)

    Molinero, J.; Samper, J.

    2003-01-01

    Several countries around the world are considering the final disposal of high-level radioactive waste in deep repositories located in fractured granite formations. Evaluating the long term safety of such repositories requires sound conceptual and numerical models which must consider simultaneously groundwater flow, solute transport and chemical and radiological processes. These models are being developed from data and knowledge gained from in situ experiments carried out at deep underground laboratories such as that of Aspo, Sweden, constructed in fractured granite. The Redox Zone Experiment is one of such experiments performed at Aspo in order to evaluate the effects of the construction of the access tunnel on the hydrogeological and hydrochemical conditions of a fracture zone intersected by the tunnel. Previous authors interpreted hydrochemical and isotopic data of this experiment using a mass-balance approach based on a qualitative description of groundwater flow conditions. Such an interpretation, however, is subject to uncertainties related to an over-simplified conceptualization of groundwater flow. Here we present numerical models of groundwater flow and solute transport for this fracture zone. The first model is based on previously published conceptual model. It presents noticeable un consistencies and fails to match simultaneously observed draw downs and chloride breakthrough curves. To overcome its limitations, a revised flow and transport model is presented which relies directly on available hydrodynamic and transport parameters, is based on the identification of appropriate flow and transport boundary conditions and uses, when needed, solute data extrapolated from nearby fracture zones. A significant quantitative improvement is achieved with the revised model because its results match simultaneously drawdown and chloride data. Other improvements are qualitative and include: ensuring consistency of hydrodynamic and hydrochemical data and avoiding

  10. Simulations of pressure and salinity fields at Aespoe

    Energy Technology Data Exchange (ETDEWEB)

    Loefman, J. [VTT Energy, Espoo (Finland)

    1997-04-01

    The primary objective of this study was to examine whether the geochemical field data from Aespoe could be interpreted and understood by means of numerical simulations for flow and transport. A site-specific simulation model for groundwater flow and salt transport was developed on the basis of the field investigations. Both steady-state and transient simulations of flow and transport were performed. In the transient simulations, land uplift and the effect of diffusion into/from the matrix blocks with stagnant water were taken into account. The computational results were evaluated on the basis of the experimental values for the pressure and salt concentration.

  11. Simulations of pressure and salinity fields at Aespoe

    International Nuclear Information System (INIS)

    Loefman, J.

    1997-01-01

    The primary objective of this study was to examine whether the geochemical field data from Aespoe could be interpreted and understood by means of numerical simulations for flow and transport. A site-specific simulation model for groundwater flow and salt transport was developed on the basis of the field investigations. Both steady-state and transient simulations of flow and transport were performed. In the transient simulations, land uplift and the effect of diffusion into/from the matrix blocks with stagnant water were taken into account. The computational results were evaluated on the basis of the experimental values for the pressure and salt concentration

  12. Effects of aged sorption on pesticide leaching to groundwater simulated with PEARL

    NARCIS (Netherlands)

    Boesten, Jos J.T.I.

    2017-01-01

    Leaching to groundwater is an important element of the regulatory risk assessment of pesticides in western countries. Including aged sorption in this assessment is relevant because there is ample evidence of this process and because it leads to a decrease in simulated leaching. This work assesses

  13. Subsurface Transport Over Reactive Multiphases (STORM): A Parallel, Coupled, Nonisothermal Multiphase Flow, Reactive Transport, and Porous Medium Alteration Simulator, Version 3.0

    International Nuclear Information System (INIS)

    Bacon, Diana H.; White, Mark D.; McGrail, B PETER

    2004-01-01

    The U.S. Department of Energy must approve a performance assessment (PA) to support the design, construction, approval, and closure of disposal facilities for immobilized low-activity waste (ILAW) currently stored in underground tanks at Hanford, Washington. A critical component of the PA is to provide quantitative estimates of radionuclide release rates from the engineered portion of the disposal facilities. Computer simulations are essential for this purpose because impacts on groundwater resources must be projected to periods of 10,000 years and longer. The computer code selected for simulating the radionuclide release rates is the Subsurface Transport Over Reactive Multiphases (STORM) simulator. The STORM simulator solves coupled conservation equations for component mass and energy that describe subsurface flow over aqueous and gas phases through variably saturated geologic media. The resulting flow fields are used to sequentially solve conservation equations for reactive aqueous phase transport through variably saturated geologic media. These conservation equations for component mass, energy, and solute mass are partial differential equations that mathematically describe flow and transport through porous media. The STORM simulator solves the governing-conservation equations and constitutive functions using numerical techniques for nonlinear systems. The partial differential equations governing thermal and fluid flow processes are solved by the integral volume finite difference method. These governing equations are solved simultaneously using Newton-Raphson iteration. The partial differential equations governing reactive solute transport are solved using either an operator split technique where geochemical reactions and solute transport are solved separately, or a fully coupled technique where these equations are solved simultaneously. The STORM simulator is written in the FORTRAN 77 language, following American National Standards Institute (ANSI) standards

  14. Subsurface Transport Behavior of Micro-Nano Bubbles and Potential Applications for Groundwater Remediation

    Directory of Open Access Journals (Sweden)

    Hengzhen Li

    2013-12-01

    Full Text Available Micro-nano bubbles (MNBs are tiny bubbles with diameters on the order of micrometers and nanometers, showing great potential in environmental remediation. However, the application is only in the beginning stages and remains to be intensively studied. In order to explore the possible use of MNBs in groundwater contaminant removal, this study focuses on the transport of MNBs in porous media and dissolution processes. The bubble diameter distribution was obtained under different conditions by a laser particle analyzer. The permeability of MNB water through sand was compared with that of air-free water. Moreover, the mass transfer features of dissolved oxygen in water with MNBs were studied. The results show that the bubble diameter distribution is influenced by the surfactant concentration in the water. The existence of MNBs in pore water has no impact on the hydraulic conductivity of sand. Furthermore, the dissolved oxygen (DO in water is greatly increased by the MNBs, which will predictably improve the aerobic bioremediation of groundwater. The results are meaningful and instructive in the further study of MNB research and applications in groundwater bioremediation.

  15. Hanford statewide groundwater flow and transport model calibration report

    International Nuclear Information System (INIS)

    Law, A.; Panday, S.; Denslow, C.; Fecht, K.; Knepp, A.

    1996-04-01

    This report presents the results of the development and calibration of a three-dimensional, finite element model (VAM3DCG) for the unconfined groundwater flow system at the Hanford Site. This flow system is the largest radioactively contaminated groundwater system in the United States. Eleven groundwater plumes have been identified containing organics, inorganics, and radionuclides. Because groundwater from the unconfined groundwater system flows into the Columbia River, the development of a groundwater flow model is essential to the long-term management of these plumes. Cost effective decision making requires the capability to predict the effectiveness of various remediation approaches. Some of the alternatives available to remediate groundwater include: pumping contaminated water from the ground for treatment with reinjection or to other disposal facilities; containment of plumes by means of impermeable walls, physical barriers, and hydraulic control measures; and, in some cases, management of groundwater via planned recharge and withdrawals. Implementation of these methods requires a knowledge of the groundwater flow system and how it responds to remedial actions

  16. Natural organics in groundwaters and their potential effect on contaminant transport in granitic rock

    International Nuclear Information System (INIS)

    Vilks, P.; Bachinski, D.B.; Richer, D.

    1996-07-01

    Naturally occurring organics in groundwaters of the Whiteshell Research Area (WRA) of southern Manitoba and of the Atikokan Research Area of northwestern Ontario were investigated to assess their potential role in radionuclide transport within granite fractures of the Canadian Shield. A survey of dissolved organic carbon (DOC) concentrations, carried out to determine the variability in the organic content of these groundwaters, showed average concentrations in WRA deep groundwaters of 0.8 ± 0.1 mg/L for Fracture Zone 2, 0.8 ± 0.4 mg/L for near-vertical fractures, and 2.3 ± 0.8 mg/L for deeper saline groundwater. Surface waters and near-surface groundwaters had significantly higher DOC with 29.2 ± 0.6 mg/L in streams from the East Swamp. The DOC consisted mainly of hydrophilic neutral compounds 60 to 75%, and hydrophobic and hydrophilic acids 23 to 39%, along with very small amounts of hydrophobic bases and neutrals, and hydrophilic bases. The average complexing capacity of natural organics in WRA deep groundwaters was calculated to be 6.7 x 10 -6 eq/L. The ability of these organics to complex radionuclides was tested using conditional stability constants from the literature for humic complex formation with trivalent, tetravalent, pentavalent and hexavalent actinides. The chemistries of Np(V) and U(VI) were predicted to be dominated by inorganic complexes and not significantly affected by organics. Accurate predictions for AM(III) and Th(IV) could not be made since the literature contains a wide range in values of stability constants for humic complexes with these elements. Surface waters and near-surface groundwaters in many areas of the Canadian Shield contain enough humics to complex a significant fraction of dissolved actinides. Radiocarbon ages of humics from WRA groundwater varied between 3600 and 6200 years before present, indicating that a component of humic substances in deep groundwaters must originate from near-surface waters. 54 refs., 15 tabs., 5

  17. Preliminary Groundwater Simulations To Compare Different Reconstruction Methods of 3-d Alluvial Heterogeneity

    Science.gov (United States)

    Teles, V.; de Marsily, G.; Delay, F.; Perrier, E.

    Alluvial floodplains are extremely heterogeneous aquifers, whose three-dimensional structures are quite difficult to model. In general, when representing such structures, the medium heterogeneity is modeled with classical geostatistical or Boolean meth- ods. Another approach, still in its infancy, is called the genetic method because it simulates the generation of the medium by reproducing sedimentary processes. We developed a new genetic model to obtain a realistic three-dimensional image of allu- vial media. It does not simulate the hydrodynamics of sedimentation but uses semi- empirical and statistical rules to roughly reproduce fluvial deposition and erosion. The main processes, either at the stream scale or at the plain scale, are modeled by simple rules applied to "sediment" entities or to conceptual "erosion" entities. The model was applied to a several kilometer long portion of the Aube River floodplain (France) and reproduced the deposition and erosion cycles that occurred during the inferred climate periods (15 000 BP to present). A three-dimensional image of the aquifer was gener- ated, by extrapolating the two-dimensional information collected on a cross-section of the floodplain. Unlike geostatistical methods, this extrapolation does not use a statis- tical spatial analysis of the data, but a genetic analysis, which leads to a more realistic structure. Groundwater flow and transport simulations in the alluvium were carried out with a three-dimensional flow code or simulator (MODFLOW), using different rep- resentations of the alluvial reservoir of the Aube River floodplain: first an equivalent homogeneous medium, and then different heterogeneous media built either with the traditional geostatistical approach simulating the permeability distribution, or with the new genetic model presented here simulating sediment facies. In the latter case, each deposited entity of a given lithology was assigned a constant hydraulic conductivity value. Results of these

  18. Transport and mass exchange processes in sand and gravel aquifers (v.1)

    International Nuclear Information System (INIS)

    Moltyaner, G.

    1990-01-01

    The objectives of this conference were to exchange information on promising field measurement techniques used for the characterization of spatial variability of geologic formations and on new methods used for quantifying the effect of spatial variability on groundwater flow and transport of materials; to discuss novel developments in the theory of transport processes and simulation methods; and to present views and opinions on future initiatives and directions in the design of large-scale field tracer experiments and the development of conceptual and mathematical models of transport and mass exchange processes. The 46 papers presented in these proceedings are divided into six sections: field studies of transport processes; groundwater tracers and novel field measurement techniques; promising methods and field measurement techniques for quantifying the effect of geological heterogeneities on groundwater flow and transport; novel developments in the theory of transport processes; numerical modelling of transport and mass exchange processes; and field and modelling studies of mass exchange processes. (L.L.)

  19. Arsenic transport in groundwater, surface water, and the hyporheic zone of a mine-influenced stream-aquifer system

    OpenAIRE

    Brown, Brendan

    2005-01-01

    We investigated the transport of dissolved arsenic in groundwater, surface water and the hyporheic zone in a stream-aquifer system influenced by an abandoned arsenopyrite mine. Mine tailing piles consisting of a host of arsenic-bearing minerals including arsenopyrite and scorodite remain adjacent to the stream and represent a continuous source of arsenic. Arsenic loads from the stream, springs, and groundwater were quantified at the study reach on nine dates from January to August 2005 and ...

  20. Upscaling of lysimeter measurements to regional groundwater nitrate distribution

    Science.gov (United States)

    Klammler, Gernot; Fank, Johann; Kupfersberger, Hans; Rock, Gerhard

    2015-04-01

    For many European countries nitrate leaching from the soil zone into the aquifer due to surplus application of mineral fertilizer and animal manure by farmers constitutes the most important threat to groundwater quality. This is a diffuse pollution situation and measures to change agricultural production have to be investigated at the aquifer scale to safeguard drinking water supply from shallow groundwater resources Lysimeters are state-of-the-art measurements for water and solute fluxes through the unsaturated zone towards groundwater at the point scale, but due to regional heterogeneities (especially concerning soil conditions) lysimeters cannot provide aquifer-wide groundwater recharge and solute leaching. Thus, in this work the numerical simulation model SIMWASER/STOTRASIM (Stenitzer, 1988; Feichtinger, 1998) for quantifying groundwater recharge and nitrate leaching at aquifer scale is applied. Nevertheless, according to Groenendijk et al. (2014) a model calibration by means of lysimeter measurements is essential, since uncalibrated models are generally far from acceptable. Thus, a lysimeter provides the basis for the parameterization of numerical simulation models. To quantify also the impact on regional nitrate distribution in the groundwater, we couple the unsaturated zone model SIMWASER/STOTRASIM with the saturated groundwater flow and solute transport model FELOW (Diersch, 2009) sequentially. In principal, the problem could be solved by the 3 dimensional equation describing variable saturated groundwater flow and solute transport. However, this is computationally prohibitive due to the temporal and spatial scope of the task, particularly in the framework of running numerous simulations to compromise between conflicting interests (i.e. good groundwater status and high agricultural yield). To account for the unknown regional distribution of crops grown and amount, timing and kind of fertilizers used a stochastic tool (Klammler et al, 2011) is developed that

  1. SITE 94. Modelling of groundwater chemistry at Aespoe Hard Rock Laboratory

    Energy Technology Data Exchange (ETDEWEB)

    Emren, A.T. [Chalmers Univ. of Technology, Goeteborg (Sweden). Dept. of Nuclear Chemistry

    1999-02-01

    In this report a model is described, which has been able to give agreement between observed and modelled values for more than ten element concentrations (including pH and pE values). The model makes use of a number of steady state waters which are mixed naturally after which the mixtures react with minerals in the fractures. The end member waters are supposed to have been present in the fracture system during a time interval which is long enough for the rock groundwater system to have reached a steady state. Some elements, e.g. chlorine, is modelled as conservative (inert with respect to the rock). Most element concentrations cannot be explained from mixing alone. Rather reactions with the fracture walls have to be taken into account. The situation is complicated by the fact that a system comprised of groundwater and a number of fracture minerals may violate Gibb`s phase rule. In such a system, no global equilibrium state exists, and thus the water can never reach equilibrium with respect to all the fracture minerals. The end member waters eventually formed can be expected to be in a steady state condition rather than equilibrium with respect to the fracture minerals. It should be noted that such a steady state is not an equilibrium state. Rather, the water chemistry has to fluctuate as a result of spatial variability in the local mineral set. In most cases when an end member water is sampled, a large number of local waters are mixed causing the fluctuations to cancel out. The CRACKER is a program which has been developed to handle this complicated chemical situation. It couples chemistry and transport, using elaborate chemical modelling in combination with a simplified transport model. The program simulates chemical reactions of groundwater flowing through a plane fracture. The simulation results show that although the end member waters are far from equilibrium with respect to most of the minerals, they are in a steady state with respect to the rock. The chemistry

  2. SITE 94. Modelling of groundwater chemistry at Aespoe Hard Rock Laboratory

    International Nuclear Information System (INIS)

    Emren, A.T.

    1999-02-01

    In this report a model is described, which has been able to give agreement between observed and modelled values for more than ten element concentrations (including pH and pE values). The model makes use of a number of steady state waters which are mixed naturally after which the mixtures react with minerals in the fractures. The end member waters are supposed to have been present in the fracture system during a time interval which is long enough for the rock groundwater system to have reached a steady state. Some elements, e.g. chlorine, is modelled as conservative (inert with respect to the rock). Most element concentrations cannot be explained from mixing alone. Rather reactions with the fracture walls have to be taken into account. The situation is complicated by the fact that a system comprised of groundwater and a number of fracture minerals may violate Gibb's phase rule. In such a system, no global equilibrium state exists, and thus the water can never reach equilibrium with respect to all the fracture minerals. The end member waters eventually formed can be expected to be in a steady state condition rather than equilibrium with respect to the fracture minerals. It should be noted that such a steady state is not an equilibrium state. Rather, the water chemistry has to fluctuate as a result of spatial variability in the local mineral set. In most cases when an end member water is sampled, a large number of local waters are mixed causing the fluctuations to cancel out. The CRACKER is a program which has been developed to handle this complicated chemical situation. It couples chemistry and transport, using elaborate chemical modelling in combination with a simplified transport model. The program simulates chemical reactions of groundwater flowing through a plane fracture. The simulation results show that although the end member waters are far from equilibrium with respect to most of the minerals, they are in a steady state with respect to the rock. The chemistry

  3. Effects of intensive urbanization on the intrusion of shallow groundwater into deep groundwater: Examples from Bangkok and Jakarta

    International Nuclear Information System (INIS)

    Onodera, Shin-ichi; Saito, Mitsuyo; Sawano, Misa; Hosono, Takahiro; Taniguchi, Makoto; Shimada, Jun; Umezawa, Yu; Lubis, Rachmat Fajar; Buapeng, Somkid; Delinom, Robert

    2008-01-01

    Asian megacities have severe pollution problems in both coastal and urban areas. In addition, the groundwater potential has decreased and land subsidence has occurred because of intensive groundwater pumping in urban areas. To prevent the adverse effects of urbanization on groundwater quality, it is necessary to confirm the changes in groundwater flow and contaminant transport caused by urbanization. We examined the effects of urbanization on contaminant transport in groundwater. The research areas were located around Bangkok, Thailand, and akarta, Indonesia, cities with populations of approximately 8 and 12 million, respectively. Each metropolitan city is located on a river delta and is adjacent to a bay. We measured the water level and collected water samples at boreholes at multiple depths (100 to 200 m) in 2004 and 2006 in Bangkok and Jakarta, respectively. The current hydraulic potential is below sea level in both cities because of prior excess abstraction of groundwater. As a result, the direction of groundwater flow is now downward in the coastal area. The Cl - concentration and δ 18 O distributions in groundwater suggest that the decline in hydraulic potential has caused the intrusion of seawater and shallow groundwater into deep groundwater. Concentrations of Mn and NO3 - -N in groundwater suggest the intrusion of these contaminants from shallow to deep aquifers with downward groundwater flow and implies an accumulation of contaminants in deep aquifers. Therefore, it is important to recognize the possibility of future contaminant transport with the discharge of deep groundwater into the sea after the recovery of groundwater potential in the coastal areas

  4. Impact of Hypobarism During Simulated Transport on Critical Care Air Transport Team Performance

    Science.gov (United States)

    2017-04-26

    AFRL-SA-WP-SR-2017-0008 Impact of Hypobarism During Simulated Transport on Critical Care Air Transport Team Performance Dina...July 2014 – November 2016 4. TITLE AND SUBTITLE Impact of Hypobarism During Simulated Transport on Critical Care Air Transport Team Performance 5a...During Critical Care Air Transport Team Advanced Course validation, three-member teams consisting of a physician, nurse, and respiratory therapist

  5. Genesis and transport of hexavalent chromium in the system ophiolitic rocks - groundwater

    Science.gov (United States)

    Shchegolikhina, Anastasia; Guadagnini, Laura; Guadagnini, Alberto

    2015-04-01

    Our study aims at contributing to the quantification and characterization of chromium transport processes from host rocks and soil matrices to groundwater. We focus on dissolved hexavalent chromium detected in groundwaters of geological regions with ophiolitic rocks (ophiolites and serpentinites) inclusions due to its critical ecological impact. (Oze et al., 2004). Despite the large number of analyses on the occurrence of high concentrations of hazardous hexavalent chromium ions in natural waters, only few studies were performed with the objective of identifying and investigating the geochemical reactions which could occur in the natural system rock - groundwater - dissolved chromium (Fantoni et al., 2002, Stephen and James, 2004, Lelli et al., 2013). In this context, there is a need for integration of results obtained from diverse studies in various regions and settings to improve our knowledge repository. Our theoretical analyses are grounded and driven by practical scenarios detected in subsurface reservoirs exploited for civil and industrial use located in the Emilia-Romagna region (Italy). Available experimental datasets are complemented with data from other international regional-scale settings (Altay mountains region, Russia). Modeling of chromium transformation and migration particularly includes characterization of the multispecies geochemical system. A key aspect of our study is the analysis of the complex competitive sorption processes governing heavy metal evolution in groundwater. The results of the research allow assessing the critical qualitative features of the mechanisms of hexavalent chromium ion mobilization from host rocks and soils and the ensuing transformation and migration to groundwater under the influence of diverse environmental factors. The study is then complemented by the quantification of the main sources of uncertainty associated with prediction of heavy metal contamination levels in the groundwater system explored. Fantoni, D

  6. A simulation-optimization model for effective water resources management in the coastal zone

    Science.gov (United States)

    Spanoudaki, Katerina; Kampanis, Nikolaos

    2015-04-01

    -diffusion equation describing the fate and transport of contaminants introduced in a 3D turbulent flow field to the partial differential equation describing the fate and transport of contaminants in 3D transient groundwater flow systems. The model has been further developed to include the effects of density variations on surface water and groundwater flow, while the already built-in solute transport capabilities are used to simulate salinity interactions. The refined model is based on the finite volume method using a cell-centred structured grid, providing thus flexibility and accuracy in simulating irregular boundary geometries. For addressing water resources management problems, simulation models are usually externally coupled with optimisation-based management models. However this usually requires a very large number of iterations between the optimisation and simulation models in order to obtain the optimal management solution. As an alternative approach, for improved computational efficiency, an Artificial Neural Network (ANN) is trained as an approximate simulator of IRENE. The trained ANN is then linked to a Genetic Algorithm (GA) based optimisation model for managing salinisation problems in the coastal zone. The linked simulation-optimisation model is applied to a hypothetical study area for performance evaluation. Acknowledgement The work presented in this paper has been funded by the Greek State Scholarships Foundation (IKY), Fellowships of Excellence for Postdoctoral Studies (Siemens Program), 'A simulation-optimization model for assessing the best practices for the protection of surface water and groundwater in the coastal zone', (2013 - 2015). References Spanoudaki, K., Stamou, A.I. and Nanou-Giannarou, A. (2009). Development and verification of a 3-D integrated surface water-groundwater model. Journal of Hydrology, 375 (3-4), 410-427. Spanoudaki, K. (2010). Integrated numerical modelling of surface water groundwater systems (in Greek). Ph.D. Thesis, National Technical

  7. Simulation and Prediction of Groundwater Pollution from Planned Feed Additive Project in Nanning City Based on GMS Model

    Science.gov (United States)

    Liang, Yimin; Lan, Junkang; Wen, Zhixiong

    2018-01-01

    In order to predict the pollution of underground aquifers and rivers by the proposed project, Specialized hydrogeological investigation was carried out. After hydrogeological surveying and mapping, drilling, and groundwater level monitoring, the scope of the hydrogeological unit and the regional hydrogeological condition were found out. The permeability coefficients of the aquifers were also obtained by borehole water injection tests. In order to predict the impact on groundwater environment by the project, a GMS software was used in numerical simulation. The simulation results show that when unexpected sewage leakage accident happened, the pollutants will be gradually diluted by groundwater, and the diluted contaminants will slowly spread to southeast with groundwater flow, eventually they are discharged into Gantang River. However, the process of the pollutants discharging into the river is very long, the long-term dilution of the river water will keep Gantang River from being polluted.

  8. Simulation of ground-water flow in coastal Georgia and adjacent parts of South Carolina and Florida-predevelopment, 1980, and 2000

    Science.gov (United States)

    Payne, Dorothy F.; Rumman, Malek Abu; Clarke, John S.

    2005-01-01

    A digital model was developed to simulate steady-state ground-water flow in a 42,155-square-mile area of coastal Georgia and adjacent parts of South Carolina and Florida. The model was developed to (1) understand and refine the conceptual model of regional ground-water flow, (2) serve as a framework for the development of digital subregional ground-water flow and solute-transport models, and (3) serve as a tool for future evaluations of hypothetical pumping scenarios used to facilitate water management in the coastal area. Single-density ground-water flow was simulated using the U.S. Geological Survey finite-difference code MODFLOW-2000 for mean-annual conditions during predevelopment (pre?1900) and the years 1980 and 2000. The model comprises seven layers: the surficial aquifer system, the Brunswick aquifer system, the Upper Floridan aquifer, the Lower Floridan aquifer, and the intervening confining units. A combination of boundary conditions was applied, including a general-head boundary condition on the top active cells of the model and a time-variable fixed-head boundary condition along part of the southern lateral boundary. Simulated heads for 1980 and 2000 conditions indicate a good match to observed values, based on a plus-or-minus 10-foot (ft) calibration target and calibration statistics. The root-mean square of residual water levels for the Upper Floridan aquifer was 13.0 ft for the 1980 calibration and 9.94 ft for the 2000 calibration. Some spatial patterns of residuals were indicated for the 1980 and 2000 simulations, and are likely a result of model-grid cell size and insufficiently detailed hydraulic-property and pumpage data in some areas. Simulated potentiometric surfaces for predevelopment, 1980, and 2000 conditions all show major flow system features that are indicated by estimated peotentiometric maps. During 1980?2000, simulated water levels at the centers of pumping at Savannah and Brunswick rose more than 20 ft and 8 ft, respectively, in

  9. Site scale groundwater flow in Haestholmen

    International Nuclear Information System (INIS)

    Loefman, J.

    1999-05-01

    Groundwater flow modelling on the site scale has been an essential part of site investigation work carried out at different locations since 1986. The objective of the modelling has been to provide results that characterise the groundwater flow conditions deep in the bedrock. The main result quantities can be used for evaluation of the investigation sites and of the preconditions for safe final disposal - of spent nuclear fuel. This study represents the groundwater flow modelling at Haestholmen, and it comprises the transient flow analysis taking into account the effects of density variations and the repository as well as the post-glacial land uplift. The analysis is performed by means of numerical finite element simulation of coupled and transient groundwater flow and solute transport carried out up to 10000 years into the future. This work provides also the results for the site-specific data needs for the block scale groundwater flow modelling at Haestholmen. Conceptually the fractured bedrock is divided into hydraulic units: the planar fracture zones and the remaining part of the bedrock. The equivalent-continuum (EC) model is applied so that each hydraulic unit is treated as a homogeneous and isotropic continuum with representative average characteristics. All the fracture zones are modelled explicitly and represented by two-dimensional finite elements. A site-specific simulation model for groundwater flow and solute transport is developed on the basis of the latest hydrogeological and hydrogeochemical field investigations at Haestholmen. The present topography together with a mathematical model describing the land uplift at the Haestholmen area are employed as a boundary condition at the surface of the model. The overall flow pattern is mostly controlled by the local variations in the topography and by the highly transmissive fracture zones. Near the surface the flow spreads out to offshore and to the lower areas of topography in all directions away from

  10. Application of MODFLOW and geographic information system to groundwater flow simulation in North China Plain, China

    Science.gov (United States)

    Wang, Shiqin; Shao, Jingli; Song, Xianfang; Zhang, Yongbo; Huo, Zhibin; Zhou, Xiaoyuan

    2008-10-01

    MODFLOW is a groundwater modeling program. It can be compiled and remedied according to the practical applications. Because of its structure and fixed data format, MODFLOW can be integrated with Geographic Information Systems (GIS) technology for water resource management. The North China Plain (NCP), which is the politic, economic and cultural center of China, is facing with water resources shortage and water pollution. Groundwater is the main water resource for industrial, agricultural and domestic usage. It is necessary to evaluate the groundwater resources of the NCP as an entire aquifer system. With the development of computer and internet information technology it is also necessary to integrate the groundwater model with the GIS technology. Because the geological and hydrogeological data in the NCP was mainly in MAPGIS format, the powerful function of GIS of disposing of and analyzing spatial data and computer languages such as Visual C and Visual Basic were used to define the relationship between the original data and model data. After analyzing the geological and hydrogeological conditions of the NCP, the groundwater flow numerical simulation modeling was constructed with MODFLOW. On the basis of GIS, a dynamic evaluation system for groundwater resources under the internet circumstance was completed. During the process of constructing the groundwater model, a water budget was analyzed, which showed a negative budget in the NCP. The simulation period was from 1 January 2002 to 31 December 2003. During this period, the total recharge of the groundwater system was 49,374 × 106 m3 and the total discharge was 56,530 × 106 m3 the budget deficit was -7,156 × 106 m3. In this integrated system, the original data including graphs and attribution data could be stored in the database. When the process of evaluating and predicting groundwater flow was started, these data were transformed into files that the core program of MODFLOW could read. The calculated water

  11. Effects of recharge, Upper Floridan aquifer heads, and time scale on simulated ground-water exchange with Lake Starr, a seepage lake in central Florida

    Science.gov (United States)

    Swancar, Amy; Lee, Terrie Mackin

    2003-01-01

    Lake Starr and other lakes in the mantled karst terrain of Florida's Central Lake District are surrounded by a conductive surficial aquifer system that receives highly variable recharge from rainfall. In addition, downward leakage from these lakes varies as heads in the underlying Upper Floridan aquifer change seasonally and with pumpage. A saturated three-dimensional finite-difference ground-water flow model was used to simulate the effects of recharge, Upper Floridan aquifer heads, and model time scale on ground-water exchange with Lake Starr. The lake was simulated as an active part of the model using high hydraulic conductivity cells. Simulated ground-water flow was compared to net ground-water flow estimated from a rigorously derived water budget for the 2-year period August 1996-July 1998. Calibrating saturated ground-water flow models with monthly stress periods to a monthly lake water budget will result in underpredicting gross inflow to, and leakage from, ridge lakes in Florida. Underprediction of ground-water inflow occurs because recharge stresses and ground-water flow responses during rainy periods are averaged over too long a time period using monthly stress periods. When inflow is underestimated during calibration, leakage also is underestimated because inflow and leakage are correlated if lake stage is maintained over the long term. Underpredicted leakage reduces the implied effect of ground-water withdrawals from the Upper Floridan aquifer on the lake. Calibrating the weekly simulation required accounting for transient responses in the water table near the lake that generated the greater range of net ground-water flow values seen in the weekly water budget. Calibrating to the weekly lake water budget also required increasing the value of annual recharge in the nearshore region well above the initial estimate of 35 percent of the rainfall, and increasing the hydraulic conductivity of the deposits around and beneath the lake. To simulate the total

  12. Numerical simulation of groundwater movement and managed aquifer recharge from Sand Hollow Reservoir, Hurricane Bench area, Washington County, Utah

    Science.gov (United States)

    Marston, Thomas M.; Heilweil, Victor M.

    2012-01-01

    The Hurricane Bench area of Washington County, Utah, is a 70 square-mile area extending south from the Virgin River and encompassing Sand Hollow basin. Sand Hollow Reservoir, located on Hurricane Bench, was completed in March 2002 and is operated primarily as a managed aquifer recharge project by the Washington County Water Conservancy District. The reservoir is situated on a thick sequence of the Navajo Sandstone and Kayenta Formation. Total recharge to the underlying Navajo aquifer from the reservoir was about 86,000 acre-feet from 2002 to 2009. Natural recharge as infiltration of precipitation was approximately 2,100 acre-feet per year for the same period. Discharge occurs as seepage to the Virgin River, municipal and irrigation well withdrawals, and seepage to drains at the base of reservoir dams. Within the Hurricane Bench area, unconfined groundwater-flow conditions generally exist throughout the Navajo Sandstone. Navajo Sandstone hydraulic-conductivity values from regional aquifer testing range from 0.8 to 32 feet per day. The large variability in hydraulic conductivity is attributed to bedrock fractures that trend north-northeast across the study area.A numerical groundwater-flow model was developed to simulate groundwater movement in the Hurricane Bench area and to simulate the movement of managed aquifer recharge from Sand Hollow Reservoir through the groundwater system. The model was calibrated to combined steady- and transient-state conditions. The steady-state portion of the simulation was developed and calibrated by using hydrologic data that represented average conditions for 1975. The transient-state portion of the simulation was developed and calibrated by using hydrologic data collected from 1976 to 2009. Areally, the model grid was 98 rows by 76 columns with a variable cell size ranging from about 1.5 to 25 acres. Smaller cells were used to represent the reservoir to accurately simulate the reservoir bathymetry and nearby monitoring wells; larger

  13. Agricultural Recharge Practices for Managing Nitrate in Regional Groundwater: Time-Resolution Assessment of Numerical Modeling Approach

    Science.gov (United States)

    Bastani, M.; Harter, T.

    2017-12-01

    Intentional recharge practices in irrigated landscapes are promising options to control and remediate groundwater quality degradation with respect to nitrate. To better understand the effect of these practices, a fully 3D transient heterogeneous transport model simulation is developed using MODFLOW and MT3D. The model is developed for a long-term study of nitrate improvements in an alluvial groundwater basin in Eastern San Joaquin Valley, CA. Different scenarios of agricultural recharge strategies including crop type change and winter flood flows are investigated. Transient simulations with high spatio-temporal resolutions are performed. We then consider upscaling strategies that would allow us to simplify the modeling process such that it can be applied at a very large basin-scale (1000s of square kilometers) for scenario analysis. We specifically consider upscaling of time-variant boundary conditions (both internal and external) that have significant influence on calculation cost of the model. We compare monthly transient stresses to upscaled annual and further upscaled average steady-state stresses on nitrate transport in groundwater under recharge scenarios.

  14. Natural colloids in groundwater from granite and their potential impact on radionuclide transport

    International Nuclear Information System (INIS)

    Vilks, P.; Bachinski, D.B.

    1997-03-01

    AECL has submitted an Environmental Impact Statement (EIS) to evaluate the concept of nuclear fuel disposal at depth in crystalline rock of the Canadian Shield. As part of geochemical studies carried out in support of the EIS, the role of natural groundwater colloids (0.001 to 0.45 μm) and suspended particles (>0.45 μm) in radionuclide transport in granite rock has been investigated. This report summarizes the results of investigations carried out in groundwaters from the Whiteshell Research Area (WRA) of southern Manitoba and the Atikokan Research Area (ARA) of northwestern Ontario to determine the concentrations, size distributions, and compositions of natural particles in groundwaters from the Canadian Shield. Particles from groundwater were isolated by ultrafiltration under a nitrogen atmosphere and particle concentrations and size distributions were determined by filtration, and by laser-based particle counting and size analysis. Groundwaters from Canadian Shield granites contain particles in a broad range of sizes, with no one particular size being dominant. Particle compositions include aluminosilicates, Fe oxides, carbonate and organics. Suspended particles are most likely generated by the mobilization of fracture-lining minerals by groundwater flow, while colloids are formed by a combination of precipitation and mobilization of colloidal material from fracture surfaces. The average concentration of 0.01 to 0.45 μm colloids in WRA groundwaters was 1.05 ± 0.14 mg/L. Average colloid concentrations were slightly higher in the more highly fractured ARA, although the highest observed colloid concentration in the ARA was below the 7 mg/L maximum observed in a sample from the WRA. The existence of colloids in the 0.001 to 0.01 μm size range was demonstrated using the results of chemical analysis of particle concentrates and data obtained with the laser-based Ultrafine Particle Size Analyzer (UPA). The WRA groundwaters contain on average about 2.7 mg/L of 0

  15. Evaluation of groundwater-surface water interaction through groundwater modelling: simulation of the effects of removal of a dam along a river at a contaminated site in Northern France

    Directory of Open Access Journals (Sweden)

    Michele Remonti

    2013-06-01

    Full Text Available A numerical groundwater flow model has been developed for an industrial site bounded by a river in in Basse Normandie, Northern France. The scope of the work was the optimisation of the existing groundwater pump and treat system and the prediction of possible effects on groundwater circulation after the future removal of a dam located along the river. The model has been implemented with the finite difference code MODFLOW 2005 and represents an area with an extension of approximately 800 x 500 m. It has been calibrated using static conditions groundwater head data (wells deactivated and verified with 1 abstracting conditions (wells abstracting head data, 2 simulating pumping tests with transient simulations and 3 comparing measured average river baseflow with modelled river drainage. The model indicates that the hydraulic barrier in the present abstraction scenario has some problematic areas and needs some improvements, as confirmed by the hydrochemical data of the river water. A first predictive scenario has been developed to optimise the barrier, indicating that a flow rate of 0.5 m3/h each at three new barrier wells, in addition to the present abstraction scenario, should ensure the hydraulic containment of the site. A second predictive scenario simulates the optimised groundwater abstractions without the presence of the dam along the neighbouring river. In these conditions, the river will increase the drainage effect on the aquifer, requiring a further increase in the rate of abstraction from the existing and new wells to ensure the hydraulic containment. With this paper we would like to present an example of what we think is a correct professional approach, with the design of the simplest model as possible depending on the hydrogeological conceptual model complexity, the abundance of data and the model objectives, and where multiple confirmations of the correctness of groundwater model results have been searched for.

  16. Prediction uncertainty and data worth assessment for groundwater transport times in an agricultural catchment

    Science.gov (United States)

    Zell, Wesley O.; Culver, Teresa B.; Sanford, Ward E.

    2018-06-01

    Uncertainties about the age of base-flow discharge can have serious implications for the management of degraded environmental systems where subsurface pathways, and the ongoing release of pollutants that accumulated in the subsurface during past decades, dominate the water quality signal. Numerical groundwater models may be used to estimate groundwater return times and base-flow ages and thus predict the time required for stakeholders to see the results of improved agricultural management practices. However, the uncertainty inherent in the relationship between (i) the observations of atmospherically-derived tracers that are required to calibrate such models and (ii) the predictions of system age that the observations inform have not been investigated. For example, few if any studies have assessed the uncertainty of numerically-simulated system ages or evaluated the uncertainty reductions that may result from the expense of collecting additional subsurface tracer data. In this study we combine numerical flow and transport modeling of atmospherically-derived tracers with prediction uncertainty methods to accomplish four objectives. First, we show the relative importance of head, discharge, and tracer information for characterizing response times in a uniquely data rich catchment that includes 266 age-tracer measurements (SF6, CFCs, and 3H) in addition to long term monitoring of water levels and stream discharge. Second, we calculate uncertainty intervals for model-simulated base-flow ages using both linear and non-linear methods, and find that the prediction sensitivity vector used by linear first-order second-moment methods results in much larger uncertainties than non-linear Monte Carlo methods operating on the same parameter uncertainty. Third, by combining prediction uncertainty analysis with multiple models of the system, we show that data-worth calculations and monitoring network design are sensitive to variations in the amount of water leaving the system via

  17. The evolution of groundwater flow and mass transport in Canadian shield flow domains: a methodology for numerical simulation

    International Nuclear Information System (INIS)

    Sykes, J.F.; Sudicky, E.A.; Normani, S.D.; Park, Y.J.; Cornaton, F.; McLaren, R.G.

    2007-01-01

    The Deep Geologic Repository Technology Programme (DGRTP) of Ontario Power Generation (OPG) is developing numerous approaches and methodologies for integrated and multidisciplinary site characterisation. A principal element involves the use and further development of state-of-the-art numerical simulators, and immersive visualisation technologies, while fully honouring multi-disciplinary litho-structural, hydrogeologic, paleo-hydrogeologic, geophysical, hydrogeochemical and geomechanical field data. Paleo-climate reconstructions provide surface boundary conditions for numerical models of the subsurface, furthering the understanding of groundwater flow in deep geologic systems and quantifying the effects of glaciation and deglaciation events. The use of geo-statistically plausible fracture networks conditioned on surface lineaments within the numerical models results in more physically representative and realistic characterizations of the repository site. Finally, immersive three-dimensional visualisation technology is used to query, investigate, explore and understand both the raw data, and simulation results in a spatially and temporally consistent framework. This environment allows multi-disciplinary teams of geoscience professionals to explore each other's work and can significantly enhance understanding and knowledge, thereby creating stronger linkages between the geo-scientific disciplines. The use of more physically representative and realistic conceptual models, coupled with immersive visualisation, contributes to an overall integrated approach to site characterisation, instilling further confidence in the understanding of flow system evolution. (authors)

  18. Groundwater chemistry and fracture mineralogy in the Whiteshell Research Area: Supporting data for the geosphere and biosphere transport models

    Energy Technology Data Exchange (ETDEWEB)

    Gascoyne, M.; Kamineni, D. C.

    1992-02-15

    For the case study in the Environmental Impact Statement for the Canadian Nuclear Fuel Waste Management Program, segments of the geosphere transport model (GEONET) have been assigned groundwater chemical properties and mineralogical abundances based on data obtained from analysis of groundwaters and rock types in the Whiteshell Research Area. For the groundwaters, salinity and redox conditions range from 0.5 g/L and +200 mV for the shallowest to 25 g/L and -300 mV for the deepest rock layers in the model. The salinity and redox trends of the segments are consistent with observations of other Canadian Shield environments and with concentrations of redox-sensitive species in the groundwater and fracture mineralogy. Modal volume percent of minerals estimated from thin sections of core samples have been used as input data for the same segments of GEONET. The most common minerals include chlorite, muscovite, clays (mainly illite), calcite and iron oxides. In addition, iodide concentrations for these segments have also been determined from available data to provide supporting data for the biosphere transport model (BIOTRAC). The concentrations range from 5 ug/L for shallow to 350 ug/L for deep groundwaters. Likely iodode concentrations for well water or near-surface water discharging into a lake in BIOTRAC range from 5 to 70 ug/L depending on well depth. A uniform probability distribution function is regarded as most appropriate for the groundwater data inputs and a normal distribution is most suitable for the mineralogical modal percent composition. (auth)

  19. Eco-hydrological process simulations within an integrated surface water-groundwater model

    DEFF Research Database (Denmark)

    Butts, Michael; Loinaz, Maria Christina; Bauer-Gottwein, Peter

    2014-01-01

    Integrated water resources management requires tools that can quantify changes in groundwater, surface water, water quality and ecosystem health, as a result of changes in catchment management. To address these requirements we have developed an integrated eco-hydrological modelling framework...... that allows hydrologists and ecologists to represent the complex and dynamic interactions occurring between surface water, ground water, water quality and freshwater ecosystems within a catchment. We demonstrate here the practical application of this tool to two case studies where the interaction of surface...... water and ground water are important for the ecosystem. In the first, simulations are performed to understand the importance of surface water-groundwater interactions for a restored riparian wetland on the Odense River in Denmark as part of a larger investigation of water quality and nitrate retention...

  20. Numerical simulation of pollutant transport in fractured vuggy porous karstic aquifers

    KAUST Repository

    Sun, S.

    2011-01-01

    This paper begins with presenting a mathematical model for contaminant transport in the fractured vuggy porous media of a species of contaminant (PCP). Two phases are numerically simulated for a process of contaminant and clean water infiltrated in the fractured vuggy porous media by coupling mixed finite element (MFE) method and finite volume method (FVM), both of which are locally conservative, to approximate the model. A hybrid mixed finite element (HMFE) method is applied to approximate the velocity field for the model. The convection and diffusion terms are approached by FVM and the standard MFE, respectively. The pressure distribution and temporary evolution of the concentration profiles are obtained for two phases. The average effluent concentration on the outflow boundary is obtained at different time and shows some different features from the matrix porous media. The temporal multiscale phenomena of the effluent concentration on the outlet are observed. The results show how the different distribution of the vugs and the fractures impacts on the contaminant transport and the effluent concentration on the outlet. This paper sheds light on certain features of karstic groundwater are obtained.

  1. Numerical Simulation of Pollutant Transport in Fractured Vuggy Porous Karstic Aquifers

    Directory of Open Access Journals (Sweden)

    Xiaolin Fan

    2011-01-01

    Full Text Available This paper begins with presenting a mathematical model for contaminant transport in the fractured vuggy porous media of a species of contaminant (PCP. Two phases are numerically simulated for a process of contaminant and clean water infiltrated in the fractured vuggy porous media by coupling mixed finite element (MFE method and finite volume method (FVM, both of which are locally conservative, to approximate the model. A hybrid mixed finite element (HMFE method is applied to approximate the velocity field for the model. The convection and diffusion terms are approached by FVM and the standard MFE, respectively. The pressure distribution and temporary evolution of the concentration profiles are obtained for two phases. The average effluent concentration on the outflow boundary is obtained at different time and shows some different features from the matrix porous media. The temporal multiscale phenomena of the effluent concentration on the outlet are observed. The results show how the different distribution of the vugs and the fractures impacts on the contaminant transport and the effluent concentration on the outlet. This paper sheds light on certain features of karstic groundwater are obtained.

  2. Recent Advances in the Area of Groundwater

    Science.gov (United States)

    Bahr, J. M.

    2017-12-01

    Groundwater related papers published in Water Resources Research in the last year range from experimental and modeling studies of pore scale flow and reactive transport to assessments of changes in water storage at the scale of regional aquifers enabled by satellite observations. Important societal needs motivating these studies include sustainability of groundwater resources of suitable quantity and quality for human use, protection of groundwater-dependent ecosystems in streams, wetlands, lakes and coastal areas, and assessment of the feasibility of subsurface sequestration of carbon dioxide and long-lived radioactive wastes. Eight general areas that generated ten or more papers within the period July 2016 to June 2017 are the following: aquifer heterogeneity (including geostatistical and inverse methods for parameter estimation), flow and transport in the unsaturated zone (including recharge to and evaporative losses from aquifers), multiphase flow and transport (including processes relevant to carbon sequestration), groundwater-surface water interactions (particularly hyporheic exchange), flow and transport in fractured media, novel remote sensing and geophysical techniques for aquifer characterization and assessment of groundwater dynamics, freshwater-saltwater interactions (particularly in coastal aquifers), and reactive solute transport. This presentation will highlight selected findings in each of these areas.

  3. Reactive transport models and simulation with ALLIANCES

    International Nuclear Information System (INIS)

    Leterrier, N.; Deville, E.; Bary, B.; Trotignon, L.; Hedde, T.; Cochepin, B.; Stora, E.

    2009-01-01

    Many chemical processes influence the evolution of nuclear waste storage. As a result, simulations based only upon transport and hydraulic processes fail to describe adequately some industrial scenarios. We need to take into account complex chemical models (mass action laws, kinetics...) which are highly non-linear. In order to simulate the coupling of these chemical reactions with transport, we use a classical Sequential Iterative Approach (SIA), with a fixed point algorithm, within the mainframe of the ALLIANCES platform. This approach allows us to use the various transport and chemical modules available in ALLIANCES, via an operator-splitting method based upon the structure of the chemical system. We present five different applications of reactive transport simulations in the context of nuclear waste storage: 1. A 2D simulation of the lixiviation by rain water of an underground polluted zone high in uranium oxide; 2. The degradation of the steel envelope of a package in contact with clay. Corrosion of the steel creates corrosion products and the altered package becomes a porous medium. We follow the degradation front through kinetic reactions and the coupling with transport; 3. The degradation of a cement-based material by the injection of an aqueous solution of zinc and sulphate ions. In addition to the reactive transport coupling, we take into account in this case the hydraulic retroaction of the porosity variation on the Darcy velocity; 4. The decalcification of a concrete beam in an underground storage structure. In this case, in addition to the reactive transport simulation, we take into account the interaction between chemical degradation and the mechanical forces (cracks...), and the retroactive influence on the structure changes on transport; 5. The degradation of the steel envelope of a package in contact with a clay material under a temperature gradient. In this case the reactive transport simulation is entirely directed by the temperature changes and

  4. Multicomponent mass transport model: a model for simulating migration of radionuclides in ground water

    International Nuclear Information System (INIS)

    Washburn, J.F.; Kaszeta, F.E.; Simmons, C.S.; Cole, C.R.

    1980-07-01

    This report presents the results of the development of a one-dimensional radionuclide transport code, MMT2D (Multicomponent Mass Transport), for the AEGIS Program. Multicomponent Mass Transport is a numerical solution technique that uses the discrete-parcel-random-wald (DPRW) method to directly simulate the migration of radionuclides. MMT1D accounts for: convection;dispersion; sorption-desorption; first-order radioactive decay; and n-membered radioactive decay chains. Comparisons between MMT1D and an analytical solution for a similar problem show that: MMT1D agrees very closely with the analytical solution; MMT1D has no cumulative numerical dispersion like that associated with solution techniques such as finite differences and finite elements; for current AEGIS applications, relatively few parcels are required to produce adequate results; and the power of MMT1D is the flexibility of the code in being able to handle complex problems for which analytical solution cannot be obtained. Multicomponent Mass Transport (MMT1D) codes were developed at Pacific Northwest Laboratory to predict the movement of radiocontaminants in the saturated and unsaturated sediments of the Hanford Site. All MMT models require ground-water flow patterns that have been previously generated by a hydrologic model. This report documents the computer code and operating procedures of a third generation of the MMT series: the MMT differs from previous versions by simulating the mass transport processes in systems with radionuclide decay chains. Although MMT is a one-dimensional code, the user is referred to the documentation of the theoretical and numerical procedures of the three-dimensional MMT-DPRW code for discussion of expediency, verification, and error-sensitivity analysis

  5. Computer simulations of anomalous transport

    International Nuclear Information System (INIS)

    Lee, W.W.; Okuda, H.

    1980-07-01

    Numerical plasma simulations have been carried out to study: (1) the turbulent spectrum and anomalous plasma transport associated with a steady state electrostatic drift turbulence; and (2) the anomalous energy transport of electrons due to shear-Alfven waves in a finite-β plasma. For the simulation of the steady state drift turbulence, it is observed that, in the absence of magnetic shear, the turbulence is quenched to a low level when the rotational transform is a rational number, while the turbulent level remains high for an irrational rotational transform

  6. Radionuclide transport behavior in a generic geological radioactive waste repository.

    Science.gov (United States)

    Bianchi, Marco; Liu, Hui-Hai; Birkholzer, Jens T

    2015-01-01

    We performed numerical simulations of groundwater flow and radionuclide transport to study the influence of several factors, including the ambient hydraulic gradient, groundwater pressure anomalies, and the properties of the excavation damaged zone (EDZ), on the prevailing transport mechanism (i.e., advection or molecular diffusion) in a generic nuclear waste repository within a clay-rich geological formation. By comparing simulation results, we show that the EDZ plays a major role as a preferential flowpath for radionuclide transport. When the EDZ is not taken into account, transport is dominated by molecular diffusion in almost the totality of the simulated domain, and transport velocity is about 40% slower. Modeling results also show that a reduction in hydraulic gradient leads to a greater predominance of diffusive transport, slowing down radionuclide transport by about 30% with respect to a scenario assuming a unit gradient. In addition, inward flow caused by negative pressure anomalies in the clay-rich formation further reduces transport velocity, enhancing the ability of the geological barrier to contain the radioactive waste. On the other hand, local high gradients associated with positive pressure anomalies can speed up radionuclide transport with respect to steady-state flow systems having the same regional hydraulic gradients. Transport behavior was also found to be sensitive to both geometrical and hydrogeological parameters of the EDZ. Results from this work can provide useful knowledge toward correctly assessing the post-closure safety of a geological disposal system. © 2014, National Ground Water Association.

  7. Simulating groundwater flow in karst aquifers with distributed parameter models—Comparison of porous-equivalent media and hybrid flow approaches

    Science.gov (United States)

    Kuniansky, Eve L.

    2016-09-22

    been developed that incorporate the submerged conduits as a one-dimensional pipe network within the aquifer rather than as discrete, extremely transmissive features in a porous-equivalent medium; these submerged conduit models are usually referred to as hybrid models and may include the capability to simulate both laminar and turbulent flow in the one-dimensional pipe network. Comparisons of the application of a porous-equivalent media model with and without turbulence (MODFLOW-Conduit Flow Process mode 2 and basic MODFLOW, respectively) and a hybrid (MODFLOW-Conduit Flow Process mode 1) model to the Woodville Karst Plain near Tallahassee, Florida, indicated that for annual, monthly, or seasonal average hydrologic conditions, all methods met calibration criteria (matched observed groundwater levels and average flows). Thus, the increased effort required, such as the collection of data on conduit location, to develop a hybrid model and its increased computational burden, is not necessary for simulation of average hydrologic conditions (non-laminar flow effects on simulated head and spring discharge were minimal). However, simulation of a large storm event in the Woodville Karst Plain with daily stress periods indicated that turbulence is important for matching daily springflow hydrographs. Thus, if matching streamflow hydrographs over a storm event is required, the simulation of non-laminar flow and the location of conduits are required. The main challenge in application of the methods and approaches for developing hybrid models relates to the difficulty of mapping conduit networks or having high-quality datasets to calibrate these models. Additionally, hybrid models have long simulation times, which can preclude the use of parameter estimation for calibration. Simulation of contaminant transport that does not account for preferential flow through conduits or extremely permeable zones in any approach is ill-advised. Simulation results in other karst aquifers or other

  8. Hydrogeology and simulated groundwater flow and availability in the North Fork Red River aquifer, southwest Oklahoma, 1980–2013

    Science.gov (United States)

    Smith, S. Jerrod; Ellis, John H.; Wagner, Derrick L.; Peterson, Steven M.

    2017-09-28

    On September 8, 1981, the Oklahoma Water Resources Board established regulatory limits on the maximum annual yield of groundwater (343,042 acre-feet per year) and equal-proportionate-share (EPS) pumping rate (1.0 acre-foot per acre per year) for the North Fork Red River aquifer. The maximum annual yield and EPS were based on a hydrologic investigation that used a numerical groundwater-flow model to evaluate the effects of potential groundwater withdrawals on groundwater availability in the North Fork Red River aquifer. The Oklahoma Water Resources Board is statutorily required (every 20 years) to update the hydrologic investigation on which the maximum annual yield and EPS were based. Because 20 years have elapsed since the final order was issued, the U.S. Geological Survey, in cooperation with the Oklahoma Water Resources Board, conducted an updated hydrologic investigation and evaluated the effects of potential groundwater withdrawals on groundwater flow and availability in the North Fork Red River aquifer in Oklahoma. This report describes a hydrologic investigation of the North Fork Red River aquifer that includes an updated summary of the aquifer hydrogeology. As part of this investigation, groundwater flow and availability were simulated by using a numerical groundwater-flow model.The North Fork Red River aquifer in Beckham, Greer, Jackson, Kiowa, and Roger Mills Counties in Oklahoma is composed of about 777 square miles (497,582 acres) of alluvium and terrace deposits along the North Fork Red River and tributaries, including Sweetwater Creek, Elk Creek, Otter Creek, and Elm Fork Red River. The North Fork Red River is the primary source of surface-water inflow to Lake Altus, which overlies the North Fork Red River aquifer. Lake Altus is a U.S. Bureau of Reclamation reservoir with the primary purpose of supplying irrigation water to the Lugert-Altus Irrigation District.A hydrogeologic framework was developed for the North Fork Red River aquifer and included a

  9. Arsenic in groundwater of the Red River floodplain, Vietnam: Controlling geochemical processes and reactive transport modeling

    DEFF Research Database (Denmark)

    Postma, Diederik Jan; Larsen, Flemming; Hue, N.T.M.

    2007-01-01

    The mobilization of arsenic (As) to the groundwater was studied in a shallow Holocene aquifer on the Red River flood plain near Hanoi, Vietnam. The groundwater chemistry was investigated in a transect of 100 piezometers. Results show an anoxic aquifer featuring organic carbon decomposition......(III) but some As(V) is always found. Arsenic correlates well with NH4, relating its release to organic matter decomposition and the source of As appears to be the Fe-oxides being reduced. Part of the produced Fe(II) is apparently reprecipitated as siderite containing less As. Results from sediment extraction...... chemistry over depth is homogeneous and a reactive transport model was constructed to quantify the geochemical processes along the vertical groundwater flow component. A redox zonation model was constructed using the partial equilibrium approach with organic carbon degradation in the sediment as the only...

  10. Assessment of groundwater level estimation uncertainty using sequential Gaussian simulation and Bayesian bootstrapping

    Science.gov (United States)

    Varouchakis, Emmanouil; Hristopulos, Dionissios

    2015-04-01

    Space-time geostatistical approaches can improve the reliability of dynamic groundwater level models in areas with limited spatial and temporal data. Space-time residual Kriging (STRK) is a reliable method for spatiotemporal interpolation that can incorporate auxiliary information. The method usually leads to an underestimation of the prediction uncertainty. The uncertainty of spatiotemporal models is usually estimated by determining the space-time Kriging variance or by means of cross validation analysis. For de-trended data the former is not usually applied when complex spatiotemporal trend functions are assigned. A Bayesian approach based on the bootstrap idea and sequential Gaussian simulation are employed to determine the uncertainty of the spatiotemporal model (trend and covariance) parameters. These stochastic modelling approaches produce multiple realizations, rank the prediction results on the basis of specified criteria and capture the range of the uncertainty. The correlation of the spatiotemporal residuals is modeled using a non-separable space-time variogram based on the Spartan covariance family (Hristopulos and Elogne 2007, Varouchakis and Hristopulos 2013). We apply these simulation methods to investigate the uncertainty of groundwater level variations. The available dataset consists of bi-annual (dry and wet hydrological period) groundwater level measurements in 15 monitoring locations for the time period 1981 to 2010. The space-time trend function is approximated using a physical law that governs the groundwater flow in the aquifer in the presence of pumping. The main objective of this research is to compare the performance of two simulation methods for prediction uncertainty estimation. In addition, we investigate the performance of the Spartan spatiotemporal covariance function for spatiotemporal geostatistical analysis. Hristopulos, D.T. and Elogne, S.N. 2007. Analytic properties and covariance functions for a new class of generalized Gibbs

  11. Hydrologic transport of radionuclides from low-level waste burial grounds

    International Nuclear Information System (INIS)

    Duguid, J.O.

    1979-01-01

    The physical characteristics of the virgin site and of the disturbed site after burial drastically affect the transport of radionuclides from buried waste. The disturbance of the land surface during the waste burial operation causes changes in the local ground-water regimen. These changes can increase the water table elevation and cause the occurrence of perched water in burial trenches. The combination of these changes may lead to submersion of the waste and to increased radionuclide transport from the burial site in both surface and groundwater. Factors such as ion exchange can retard or in some cases, with competing ions, can also mobilize radionuclides and increase their discharge into ground and surface water. Because of complexing agents (organics) contained in the waste, increased mobility of some radionuclides can be expected. The chemical form of radionuclides in the water, the ground-water quality, and the chemistry of the geologic formation in which the waste is buried all influence the movement of radionuclides in the hydrologic system. For the assessment of the environmental impact of low-level waste burial, models capable of simulating both the chemical and the physical factors that affect hydrologic transport must be available. Several models for conducting such simulation are presently available. However, the input parameters used in these models are highly variable; and the accuracy of parameter measurement must be considered in evaluating the reliability of simulated results

  12. Numerical simulations of groundwater flow and solute transport in the Lake 233 aquifer

    Energy Technology Data Exchange (ETDEWEB)

    Klukas, M H; Moltyaner, G L

    1995-05-01

    A three-dimensional numerical flow model of the Lake 233 aquifer underlying the site of the proposed Intrusion Resistant Underground Structure (IRUS) for low level waste disposal is developed. A reference hydraulic conductivity distribution incorporating the key stratigraphic units and field estimates of recharge from Lake 233 are used as model input. The model was calibrated against the measured hydraulic head distribution, the flowpath of a historic {sup 90}Sr plume in the aquifer and measured groundwater velocities. (author). 23 refs., 4 tabs., 31 figs.

  13. Numerical simulations of groundwater flow and solute transport in the Lake 233 aquifer

    International Nuclear Information System (INIS)

    Klukas, M.H.; Moltyaner, G.L.

    1995-05-01

    A three-dimensional numerical flow model of the Lake 233 aquifer underlying the site of the proposed Intrusion Resistant Underground Structure (IRUS) for low level waste disposal is developed. A reference hydraulic conductivity distribution incorporating the key stratigraphic units and field estimates of recharge from Lake 233 are used as model input. The model was calibrated against the measured hydraulic head distribution, the flowpath of a historic 90 Sr plume in the aquifer and measured groundwater velocities. (author). 23 refs., 4 tabs., 31 figs

  14. Transport of volatile organic compounds across the capillary fringe

    Science.gov (United States)

    McCarthy, Kathleen A.; Johnson, Richard L.

    1993-01-01

    Physical experiments were conducted to investigate the transport of a dissolved volatile organic compound (trichloroethylene, TCE) from shallow groundwater to the unsaturated zone under a variety of conditions including changes in the soil moisture profile and water table position. Experimental data indicated that at moderate groundwater velocities (0.1 m/d), vertical mechanical dispersion was negligible and molecular diffusion was the dominant vertical transport mechanism. Under these conditions, TCE concentrations decreased nearly 3 orders of magnitude across the capillary fringe and soil gas concentrations remained low relative to those of underlying groundwater. Data collected during a water table drop showed a short-term increase in concentrations throughout most of the unsaturated zone, but these concentrations quickly declined and approached initial values after the water table was returned to its original level. In the deep part of the unsaturated zone, the water table drop resulted in a long-term decrease in concentrations, illustrating the effects of hysteresis in the soil moisture profile. A two-dimensional random walk advection-diffusion model was developed to simulate the experimental conditions, and numerical simulations agreed well with experimental data. A simpler, one-dimensional finite-difference diffusion-dispersion model was also developed. One-dimensional simulations based on molecular diffusion also agreed well with experimental data. Simulations which incorporated mechanical dispersion tended to overestimate flux across the capillary fringe. Good agreement between the one- and two-dimensional models suggested that a simple, one-dimensional approximation of vertical transport across the capillary fringe can be useful when conditions are appropriate.

  15. Simulation of groundwater flow and hydrologic effects of groundwater withdrawals from the Kirkwood-Cohansey aquifer system in the Pinelands of southern New Jersey

    Science.gov (United States)

    Charles, Emmanuel; Nicholson, Robert S.

    2012-01-01

    The Kirkwood-Cohansey aquifer system is an important source of present and future water supply in southern New Jersey. Because this unconfined aquifer system also supports sensitive wetland and aquatic habitats within the New Jersey Pinelands (Pinelands), water managers and policy makers need up-to-date information, data, and projections that show the effects of potential increases in groundwater withdrawals on these habitats. Finite-difference groundwater flow models (MODFLOW) were constructed for three drainage basins (McDonalds Branch Basin, 14.3 square kilometers (km2); Morses Mill Stream Basin, 21.63 km2; and Albertson Brook Basin, 52.27 km2) to estimate the effects of potential increases in groundwater withdrawals on water levels and the base-flow portion of streamflow, in wetland and aquatic habitats. Three models were constructed for each drainage basin: a transient model consisting of twenty-four 1-month stress periods (October 2004 through September 2006); a transient model to simulate the 5- to 10-day aquifer tests that were performed as part of the study; and a high-resolution, steady-state model used to assess long-term effects of increased groundwater withdrawals on water levels in wetlands and on base flow. All models were constructed with the same eight-layer structure. The smallest horizontal cell dimensions among the three model areas were 150 meters (m) for the 24-month transient models, 10 m for the steady-state models, and 3 m for the transient aquifer-test models. Boundary flows of particular interest to this study and represented separately are those for wetlands, streams, and evapotranspiration. The final variables calibrated from both transient models were then used in steady-state models to assess the long-term effects of increased groundwater withdrawals on water levels in wetlands and on base flow. Results of aquifer tests conducted in the three study areas illustrate the effects of withdrawals on water levels in wetlands and on base

  16. Hydrogeologic setting and simulation of groundwater flow near the Canterbury and Leadville Mine Drainage Tunnels, Leadville, Colorado

    Science.gov (United States)

    Wellman, Tristan P.; Paschke, Suzanne S.; Minsley, Burke; Dupree, Jean A.

    2011-01-01

    -current resistivity field survey was performed to evaluate the geologic structure of the study area. The results show that the Canterbury Tunnel is located in a downthrown structural block that is not in direct physical connection with the Leadville Mine Drainage Tunnel. The presence of this structural discontinuity implies there is no direct groundwater pathway between the tunnels along a laterally continuous bedrock unit. Water-quality results for pH and major-ion concentrations near the Canterbury Tunnel showed that acid mine drainage has not affected groundwater quality. Stable-isotope ratios of hydrogen and oxygen in water indicate that snowmelt is the primary source of groundwater recharge. On the basis of chlorofluorocarbon and tritium concentrations and mixing ratios for groundwater samples, young groundwater (groundwater recharged after 1953) was indicated at well locations upgradient from and in a fault block separate from the Canterbury Tunnel. Samples from sites downgradient from the Canterbury Tunnel were mixtures of young and old (pre-1953) groundwater and likely represent snowmelt recharge mixed with older regional groundwater that discharges from the bedrock units to the Arkansas River valley. Discharge from the Canterbury Tunnel contained the greatest percentage of old (pre-1953) groundwater with a mixture of about 25 percent young water and about 75 percent old water. A calibrated three-dimensional groundwater model representing high-flow conditions was used to evaluate large-scale flow characteristics of the groundwater and to assess whether a substantial hydraulic connection was present between the Canterbury Tunnel and Leadville Mine Drainage Tunnel. As simulated, the faults restrict local flow in many areas, but the fracture-damage zones adjacent to the faults allow groundwater to move along faults. Water-budget results indicate that groundwater flow across the lateral edges of the model controlled the majority of flow in and out of the aquifer (79 percent and

  17. Analysis of TCE Fate and Transport in Karst Groundwater Systems Using Statistical Mixed Models

    Science.gov (United States)

    Anaya, A. A.; Padilla, I. Y.

    2012-12-01

    Karst groundwater systems are highly productive and provide an important fresh water resource for human development and ecological integrity. Their high productivity is often associated with conduit flow and high matrix permeability. The same characteristics that make these aquifers productive also make them highly vulnerable to contamination and a likely for contaminant exposure. Of particular interest are trichloroethylene, (TCE) and Di-(2-Ethylhexyl) phthalate (DEHP). These chemicals have been identified as potential precursors of pre-term birth, a leading cause of neonatal complications with a significant health and societal cost. Both of these contaminants have been found in the karst groundwater formations in this area of the island. The general objectives of this work are to: (1) develop fundamental knowledge and determine the processes controlling the release, mobility, persistence, and possible pathways of contaminants in karst groundwater systems, and (2) characterize transport processes in conduit and diffusion-dominated flow under base flow and storm flow conditions. The work presented herein focuses on the use of geo-hydro statistical tools to characterize flow and transport processes under different flow regimes, and their application in the analysis of fate and transport of TCE. Multidimensional, laboratory-scale Geo-Hydrobed models (GHM) were used for this purpose. The models consist of stainless-steel tanks containing karstified limestone blocks collected from the karst aquifer formation of northern Puerto Rico. The models integrates a network of sampling wells to monitor flow, pressure, and solute concentrations temporally and spatially. Experimental work entails injecting dissolved CaCl2 tracers and TCE in the upstream boundary of the GHM while monitoring TCE and tracer concentrations spatially and temporally in the limestone under different groundwater flow regimes. Analysis of the temporal and spatial concentration distributions of solutes

  18. Uncertainties in the simulation of groundwater recharge at different scales

    Directory of Open Access Journals (Sweden)

    H. Bogena

    2005-01-01

    Full Text Available Digital spatial data always imply some kind of uncertainty. The source of this uncertainty can be found in their compilation as well as the conceptual design that causes a more or less exact abstraction of the real world, depending on the scale under consideration. Within the framework of hydrological modelling, in which numerous data sets from diverse sources of uneven quality are combined, the various uncertainties are accumulated. In this study, the GROWA model is taken as an example to examine the effects of different types of uncertainties on the calculated groundwater recharge. Distributed input errors are determined for the parameters' slope and aspect using a Monte Carlo approach. Landcover classification uncertainties are analysed by using the conditional probabilities of a remote sensing classification procedure. The uncertainties of data ensembles at different scales and study areas are discussed. The present uncertainty analysis showed that the Gaussian error propagation method is a useful technique for analysing the influence of input data on the simulated groundwater recharge. The uncertainties involved in the land use classification procedure and the digital elevation model can be significant in some parts of the study area. However, for the specific model used in this study it was shown that the precipitation uncertainties have the greatest impact on the total groundwater recharge error.

  19. A cellular automaton simulation of contaminant transport in porous media

    International Nuclear Information System (INIS)

    Freed, D.M.; Simonson, S.A.

    1995-01-01

    A simulation tool to investigate radionuclide transport in porous groundwater flow is described. The flow systems of interest are those important in determining the fate of radionuclides emplaced in an underground repository, such as saturated matrix flow, matrix and fracture flow in the unsaturated zone, and viscous fingering in porous fractures. The work discussed here is confined to consideration of saturated flow in porous media carrying a dilute, sorptive species. The simulation technique is based on a special class of cellular automata known as lattice gas automata (LGA) which are capable of predicting hydrodynamic behavior. The original two-dimensional scheme (that of Frisch et. al. known as the FHP model) used particles of unit mass traveling on a triangular lattice with unit velocity and undergoing simple collisions which conserve mass and momentum at each node. These microscopic rules go over to the incompressible Navier-Stokes equations in the macroscopic limit. One of the strengths of this technique is the natural way that heterogeneities, such as boundaries, are accommodated. Complex geometries such as those associated with porous microstructures can be modeled effectively. Several constructions based on the FHP model have been devised, including techniques to eliminate statistical noise, extension to three dimensions, and the addition of surface tension which leads to multiphase flow

  20. Simulation of groundwater flow and analysis of the effects of water-management options in the North Platte Natural Resources District, Nebraska

    Science.gov (United States)

    Peterson, Steven M.; Flynn, Amanda T.; Vrabel, Joseph; Ryter, Derek W.

    2015-08-12

    The North Platte Natural Resources District (NPNRD) has been actively collecting data and studying groundwater resources because of concerns about the future availability of the highly inter-connected surface-water and groundwater resources. This report, prepared by the U.S. Geological Survey in cooperation with the North Platte Natural Resources District, describes a groundwater-flow model of the North Platte River valley from Bridgeport, Nebraska, extending west to 6 miles into Wyoming. The model was built to improve the understanding of the interaction of surface-water and groundwater resources, and as an optimization tool, the model is able to analyze the effects of water-management options on the simulated stream base flow of the North Platte River. The groundwater system and related sources and sinks of water were simulated using a newton formulation of the U.S. Geological Survey modular three-dimensional groundwater model, referred to as MODFLOW–NWT, which provided an improved ability to solve nonlinear unconfined aquifer simulations with wetting and drying of cells. Using previously published aquifer-base-altitude contours in conjunction with newer test-hole and geophysical data, a new base-of-aquifer altitude map was generated because of the strong effect of the aquifer-base topography on groundwater-flow direction and magnitude. The largest inflow to groundwater is recharge originating from water leaking from canals, which is much larger than recharge originating from infiltration of precipitation. The largest component of groundwater discharge from the study area is to the North Platte River and its tributaries, with smaller amounts of discharge to evapotranspiration and groundwater withdrawals for irrigation. Recharge from infiltration of precipitation was estimated with a daily soil-water-balance model. Annual recharge from canal seepage was estimated using available records from the Bureau of Reclamation and then modified with canal

  1. Standardization of transportation classes for object-oriented deployment simulations.

    Energy Technology Data Exchange (ETDEWEB)

    Burke, J. F., Jr.; Howard, D. L.; Jackson, J.; Macal, C. M.; Nevins, M. R.; Van Groningen, C. N.

    1999-07-30

    Many recent efforts to integrate transportation and deployment simulations, although beneficial, have lacked a feature vital for seamless integration: a common data class representation. It is an objective of the Department of Defense (DoD) to standardize all classes used in object-oriented deployment simulations by developing a standard class attribute representation and behavior for all deployment simulations that rely on an underlying class representation. The Extensive Hierarchy and Object Representation for Transportation Simulations (EXHORT) is a collection of three hierarchies that together will constitute a standard and consistent class attribute representation and behavior that could be used directly by a large set of deployment simulations. The first hierarchy is the Transportation Class Hierarchy (TCH), which describes a significant portion of the defense transportation system; the other two deal with infrastructure and resource classes. EXHORT will allow deployment simulations to use the same set of underlying class data, ensure transparent exchanges, reduce the effort needed to integrate simulations, and permit a detailed analysis of the defense transportation system. This paper describes EXHORT's first hierarchy, the TCH, and provides a rationale for why it is a helpful tool for modeling major portions of the defense transportation system.

  2. Evaluating geothermal and hydrogeologic controls on regional groundwater temperature distribution

    Science.gov (United States)

    Burns, Erick R.; Ingebritsen, Steven E.; Manga, Michael; Williams, Colin F.

    2016-01-01

    A one-dimensional (1-D) analytic solution is developed for heat transport through an aquifer system where the vertical temperature profile in the aquifer is nearly uniform. The general anisotropic form of the viscous heat generation term is developed for use in groundwater flow simulations. The 1-D solution is extended to more complex geometries by solving the equation for piece-wise linear or uniform properties and boundary conditions. A moderately complex example, the Eastern Snake River Plain (ESRP), is analyzed to demonstrate the use of the analytic solution for identifying important physical processes. For example, it is shown that viscous heating is variably important and that heat conduction to the land surface is a primary control on the distribution of aquifer and spring temperatures. Use of published values for all aquifer and thermal properties results in a reasonable match between simulated and measured groundwater temperatures over most of the 300 km length of the ESRP, except for geothermal heat flow into the base of the aquifer within 20 km of the Yellowstone hotspot. Previous basal heat flow measurements (∼110 mW/m2) made beneath the ESRP aquifer were collected at distances of >50 km from the Yellowstone Plateau, but a higher basal heat flow of 150 mW/m2 is required to match groundwater temperatures near the Plateau. The ESRP example demonstrates how the new tool can be used during preliminary analysis of a groundwater system, allowing efficient identification of the important physical processes that must be represented during more-complex 2-D and 3-D simulations of combined groundwater and heat flow.

  3. Simulated effects of increased groundwater withdrawals in the Cave Springs area, Hixson, Tennessee

    Science.gov (United States)

    Haugh, Connor J.

    2014-01-01

    Concern for future water supplies in Tennessee has grown in recent years as a result of increased awareness of competing needs, the impact of droughts, and the need for more water to support growing populations. The U.S. Geological Survey conducts investigations to improve the knowledge about interactions of geology, climate, humans, and ecosystems with the water cycle, which is critical to understanding and optimizing water availability. The Hixson Utility District in Hamilton County, Tennessee, uses groundwater resources in the Cave Springs area as a water supply, withdrawing water from two well fields located at Cave Springs and Walkers Corner. Historically, Hixson Utility District has withdrawn about 5 million gallons per day (Mgal/d) at the Cave Springs well field and between 2 and 3 Mgal/d at the Walkers Corner well field. To assess the capacity of the groundwater resources in the Cave Springs area to meet future demands, four different scenarios of increased groundwater withdrawals were analyzed using computer model simulations.

  4. An open, object-based modeling approach for simulating subsurface heterogeneity

    Science.gov (United States)

    Bennett, J.; Ross, M.; Haslauer, C. P.; Cirpka, O. A.

    2017-12-01

    Characterization of subsurface heterogeneity with respect to hydraulic and geochemical properties is critical in hydrogeology as their spatial distribution controls groundwater flow and solute transport. Many approaches of characterizing subsurface heterogeneity do not account for well-established geological concepts about the deposition of the aquifer materials; those that do (i.e. process-based methods) often require forcing parameters that are difficult to derive from site observations. We have developed a new method for simulating subsurface heterogeneity that honors concepts of sequence stratigraphy, resolves fine-scale heterogeneity and anisotropy of distributed parameters, and resembles observed sedimentary deposits. The method implements a multi-scale hierarchical facies modeling framework based on architectural element analysis, with larger features composed of smaller sub-units. The Hydrogeological Virtual Reality simulator (HYVR) simulates distributed parameter models using an object-based approach. Input parameters are derived from observations of stratigraphic morphology in sequence type-sections. Simulation outputs can be used for generic simulations of groundwater flow and solute transport, and for the generation of three-dimensional training images needed in applications of multiple-point geostatistics. The HYVR algorithm is flexible and easy to customize. The algorithm was written in the open-source programming language Python, and is intended to form a code base for hydrogeological researchers, as well as a platform that can be further developed to suit investigators' individual needs. This presentation will encompass the conceptual background and computational methods of the HYVR algorithm, the derivation of input parameters from site characterization, and the results of groundwater flow and solute transport simulations in different depositional settings.

  5. Estimation of contaminant transport in groundwater beneath radioactive waste disposal facilities

    International Nuclear Information System (INIS)

    Wang, J.C.; Tauxe, J.D.; Lee, D.W.

    1995-01-01

    Performance assessments are required for low-level radioactive waste disposal facilities to demonstrate compliance with the performance objectives contained in either 10 CFR 61, open-quotes Licensing Requirements for Land Disposal of Radioactive Waste,close quotes or U.S. Department of Energy Order 5820.2A, open-quotes Radioactive Waste Management.close quotes The purpose of a performance assessment is to provide detailed, site-specific analyses of all credible pathways by which radionuclides could escape from the disposal facility into the environment. Among these, the groundwater pathway analysis usually involves complex numerical simulations. This paper demonstrates that the use of simpler analytical models avoids the complexity and opacity of the numerical simulations while capturing the essential physical behavior of a site

  6. Management of Nitrate m Groundwater: A Simulation Study

    Directory of Open Access Journals (Sweden)

    M. Ahmed

    2001-01-01

    Full Text Available Agriculture may cause nitrate and other chemicals to enter into groundwater systems. Nitrate in drinking water is considered a health hazard. A study was conducted to assess the extent of nitrate pollution of groundwater caused by agriculture and to evaluate the possibility of using the LEACHN model to manage nitrate entry into groundwater of agricultural areas of Al-Batinah, which is the most important agricultural region of Oman. Groundwater samples were collected and analyzed to assess the problem and to detect possible trends. Soil sampling and analyses were done to demonstrate the difference in the nitrate concentration in agricultural and non-agricultural soils. A questionnaire survey was conducted to gather information on agricultural practices, fertilizer input, and other possible sources of nitrate pollution. Results from the study show that 23% of groundwater samples have a concentration of nitrate-N concentration of 10 mg/l and 34% samples exceed 8 mg/l. Agricultural soils have higher levels of nitrate compared to non- agricultural soils. Results also demonstrate that nitrate levels in groundwater in Al-Batinah are rising. Application of the ‘LEACHN’ model demonstrated its suitability for use as a management tool to reduce nitrate leaching to groundwater by controlling fertilizer and water input.

  7. Modeling The Evolution Of A Regional Aquifer System With The California Central Valley Groundwater-Surface Water Simulation Model (C2VSIM)

    Science.gov (United States)

    Brush, C. F.; Dogrul, E. C.; Kadir, T. N.; Moncrief, M. R.; Shultz, S.; Tonkin, M.; Wendell, D.

    2006-12-01

    The finite element application IWFM has been used to develop an integrated groundwater-surface water model for California's Central Valley, an area of ~50,000 km2, to simulate the evolution of the groundwater flow system and historical groundwater-surface water interactions on a monthly time step from October 1921 to September 2003. The Central Valley's hydrologic system changed significantly during this period. Prior to 1920, most surface water flowed unimpeded from source areas in the mountains surrounding the Central Valley through the Sacramento-San Joaquin Delta to the Pacific Ocean, and groundwater largely flowed from recharge areas on the valley rim to discharge as evapotransipration in extensive marshes along the valley's axis. Rapid agricultural development led to increases in groundwater pumping from ~0.5 km3/yr in the early 1920's to 13-18 km3/yr in the 1940's to 1970's, resulting in strong vertical head gradients, significant head declines throughout the valley, and subsidence of >0.3 m over an area of 13,000 km2. Construction of numerous dams and development of an extensive surface water delivery network after 1950 altered the surface water flow regime and reduced groundwater pumping to the current ~10 km3/yr, increasing net recharge and leading to local head gradient reversals and water level recoveries. A model calibrated to the range of historical flow regimes in the Central Valley will provide robust estimations of stream-groundwater interactions for a range of projected future scenarios. C2VSIM uses the IWFM application to simulate a 3-D finite element groundwater flow process dynamically coupled with 1-D land surface, stream flow, lake and unsaturated zone processes. The groundwater flow system is represented with three layers each having 1393 elements. Land surface processes are simulated using 21 subregions corresponding to California DWR water-supply planning areas. The surface-water network is simulated using 431 stream nodes representing 72

  8. Numerical model to simulate the isotopic and heat release and transport through the geosphere from a geological repository of radioactive wastes

    International Nuclear Information System (INIS)

    Hidalgo Lopez, A.

    2002-01-01

    The aim of this research is to simulate the isotopic and heat release and transport through the geosphere, from a geological repository of high level nuclear waste. in order to achieve it, different physical processes, that have to do with the problem, are considered: groundwater flow, radioactive decay, nuclide dissolution in groundwater, heat generation, mass and heat transport. Some of these phenomena are related among the, which allows to build a coupled model,which is the starting point to generate a FORTRAN code. The flow and transport models are developed in two spatial dimensions and are integrated in space by means of a finite volume method. The time integration is fulfilled by a θ-method. Moreover, the advection-diffusion equation is solved by two finite volume techniques. In the first one a linear interpolation is used whereas in the second it is used a quadratic one. Also, a consistency an stability study of both methods is carried out in order to compare their stability zones and the errors appearing. Stability is analysed by applying the von Neumann method, which is based upon Fourier series. Although it is a classical technique when dealing with finite-difference schemes, it is here applied to two finite volume schemes. (Author)

  9. Site scale groundwater flow in Olkiluoto

    International Nuclear Information System (INIS)

    Loefman, J.

    1999-03-01

    Groundwater flow modelling on the site scale has been an essential part of site investigation work carried out at different locations since 1986. The objective of the modelling has been to provide results that characterise the groundwater flow conditions deep in the bedrock. The main result quantities can be used for evaluation of the investigation sites and of the preconditions for safe final disposal of spent nuclear fuel. This study represents the latest modelling effort at Olkiluoto (Finland), and it comprises the transient flow analysis taking into account the effects of density variations and the repository as well as the post-glacial land uplift. The analysis is performed by means of numerical finite element simulation of coupled and transient groundwater flow and solute transport carried out up to 10000 years into the future. This work provides also the results for the site-specific data needs for the block scale groundwater flow modelling at Olkiluoto. Conceptually the fractured bedrock is divided into hydraulic units: the planar fracture zones and the remaining part of the bedrock. The equivalent-continuum (EC) model is applied so that each hydraulic unit is treated as a homogeneous and isotropic continuum with representative average characteristics. All the fracture zones are modelled explicitly and represented by two-dimensional finite elements. A site-specific simulation model for groundwater flow and solute transport is developed on the basis of the latest hydrogeological and hydrogeochemical field investigations at Olkiluoto. The present groundwater table and topography together with a mathematical model describing the land uplift at the Olkiluoto area are employed as a boundary condition at the surface of the model. The overall flow pattern is mostly controlled by the local variations in the topography. Below the island of Olkiluoto the flow direction is mostly downwards, while near the shoreline and below the sea water flows horizontally and

  10. Site scale groundwater flow in Haestholmen

    Energy Technology Data Exchange (ETDEWEB)

    Loefman, J. [VTT Energy, Espoo (Finland)

    1999-05-01

    Groundwater flow modelling on the site scale has been an essential part of site investigation work carried out at different locations since 1986. The objective of the modelling has been to provide results that characterise the groundwater flow conditions deep in the bedrock. The main result quantities can be used for evaluation of the investigation sites and of the preconditions for safe final disposal - of spent nuclear fuel. This study represents the groundwater flow modelling at Haestholmen, and it comprises the transient flow analysis taking into account the effects of density variations and the repository as well as the post-glacial land uplift. The analysis is performed by means of numerical finite element simulation of coupled and transient groundwater flow and solute transport carried out up to 10000 years into the future. This work provides also the results for the site-specific data needs for the block scale groundwater flow modelling at Haestholmen. Conceptually the fractured bedrock is divided into hydraulic units: the planar fracture zones and the remaining part of the bedrock. The equivalent-continuum (EC) model is applied so that each hydraulic unit is treated as a homogeneous and isotropic continuum with representative average characteristics. All the fracture zones are modelled explicitly and represented by two-dimensional finite elements. A site-specific simulation model for groundwater flow and solute transport is developed on the basis of the latest hydrogeological and hydrogeochemical field investigations at Haestholmen. The present topography together with a mathematical model describing the land uplift at the Haestholmen area are employed as a boundary condition at the surface of the model. The overall flow pattern is mostly controlled by the local variations in the topography and by the highly transmissive fracture zones. Near the surface the flow spreads out to offshore and to the lower areas of topography in all directions away from

  11. Site scale groundwater flow in Olkiluoto

    Energy Technology Data Exchange (ETDEWEB)

    Loefman, J. [VTT Energy, Espoo (Finland)

    1999-03-01

    Groundwater flow modelling on the site scale has been an essential part of site investigation work carried out at different locations since 1986. The objective of the modelling has been to provide results that characterise the groundwater flow conditions deep in the bedrock. The main result quantities can be used for evaluation of the investigation sites and of the preconditions for safe final disposal of spent nuclear fuel. This study represents the latest modelling effort at Olkiluoto (Finland), and it comprises the transient flow analysis taking into account the effects of density variations and the repository as well as the post-glacial land uplift. The analysis is performed by means of numerical finite element simulation of coupled and transient groundwater flow and solute transport carried out up to 10000 years into the future. This work provides also the results for the site-specific data needs for the block scale groundwater flow modelling at Olkiluoto. Conceptually the fractured bedrock is divided into hydraulic units: the planar fracture zones and the remaining part of the bedrock. The equivalent-continuum (EC) model is applied so that each hydraulic unit is treated as a homogeneous and isotropic continuum with representative average characteristics. All the fracture zones are modelled explicitly and represented by two-dimensional finite elements. A site-specific simulation model for groundwater flow and solute transport is developed on the basis of the latest hydrogeological and hydrogeochemical field investigations at Olkiluoto. The present groundwater table and topography together with a mathematical model describing the land uplift at the Olkiluoto area are employed as a boundary condition at the surface of the model. The overall flow pattern is mostly controlled by the local variations in the topography. Below the island of Olkiluoto the flow direction is mostly downwards, while near the shoreline and below the sea water flows horizontally and

  12. Modeling hydrology, groundwater recharge and non-point nitrate loadings in the Himalayan Upper Yamuna basin

    International Nuclear Information System (INIS)

    Narula, Kapil K.; Gosain, A.K.

    2013-01-01

    The mountainous Himalayan watersheds are important hydrologic systems responsible for much of the water supply in the Indian sub-continent. These watersheds are increasingly facing anthropogenic and climate-related pressures that impact spatial and temporal distribution of water availability. This study evaluates temporal and spatial distribution of water availability including groundwater recharge and quality (non-point nitrate loadings) for a Himalayan watershed, namely, the Upper Yamuna watershed (part of the Ganga River basin). The watershed has an area of 11 600 km 2 with elevation ranging from 6300 to 600 m above mean sea level. Soil and Water Assessment Tool (SWAT), a physically-based, time-continuous model, has been used to simulate the land phase of the hydrological cycle, to obtain streamflows, groundwater recharge, and nitrate (NO 3 ) load distributions in various components of runoff. The hydrological SWAT model is integrated with the MODular finite difference groundwater FLOW model (MODFLOW), and Modular 3-Dimensional Multi-Species Transport model (MT3DMS), to obtain groundwater flow and NO 3 transport. Validation of various modules of this integrated model has been done for sub-basins of the Upper Yamuna watershed. Results on surface runoff and groundwater levels obtained as outputs from simulation show a good comparison with the observed streamflows and groundwater levels (Nash–Sutcliffe and R 2 correlations greater than + 0.7). Nitrate loading obtained after nitrification, denitrification, and NO 3 removal from unsaturated and shallow aquifer zones is combined with groundwater recharge. Results for nitrate modeling in groundwater aquifers are compared with observed NO 3 concentration and are found to be in good agreement. The study further evaluates the sensitivity of water availability to climate change. Simulations have been made with the weather inputs of climate change scenarios of A2, B2, and A1B for end of the century. Water yield estimates

  13. Modeling hydrology, groundwater recharge and non-point nitrate loadings in the Himalayan Upper Yamuna basin

    Energy Technology Data Exchange (ETDEWEB)

    Narula, Kapil K., E-mail: kkn2104@columbia.edu [Columbia Water Center (India Office), Columbia University, New Delhi 110 016 (India); Gosain, A.K. [Department of Civil Engineering, Indian Institute of Technology (IIT) Delhi, Hauz Khas, New Delhi 110 016 (India)

    2013-12-01

    The mountainous Himalayan watersheds are important hydrologic systems responsible for much of the water supply in the Indian sub-continent. These watersheds are increasingly facing anthropogenic and climate-related pressures that impact spatial and temporal distribution of water availability. This study evaluates temporal and spatial distribution of water availability including groundwater recharge and quality (non-point nitrate loadings) for a Himalayan watershed, namely, the Upper Yamuna watershed (part of the Ganga River basin). The watershed has an area of 11 600 km{sup 2} with elevation ranging from 6300 to 600 m above mean sea level. Soil and Water Assessment Tool (SWAT), a physically-based, time-continuous model, has been used to simulate the land phase of the hydrological cycle, to obtain streamflows, groundwater recharge, and nitrate (NO{sub 3}) load distributions in various components of runoff. The hydrological SWAT model is integrated with the MODular finite difference groundwater FLOW model (MODFLOW), and Modular 3-Dimensional Multi-Species Transport model (MT3DMS), to obtain groundwater flow and NO{sub 3} transport. Validation of various modules of this integrated model has been done for sub-basins of the Upper Yamuna watershed. Results on surface runoff and groundwater levels obtained as outputs from simulation show a good comparison with the observed streamflows and groundwater levels (Nash–Sutcliffe and R{sup 2} correlations greater than + 0.7). Nitrate loading obtained after nitrification, denitrification, and NO{sub 3} removal from unsaturated and shallow aquifer zones is combined with groundwater recharge. Results for nitrate modeling in groundwater aquifers are compared with observed NO{sub 3} concentration and are found to be in good agreement. The study further evaluates the sensitivity of water availability to climate change. Simulations have been made with the weather inputs of climate change scenarios of A2, B2, and A1B for end of the

  14. Simulation of large-scale soil water systems using groundwater data and satellite based soil moisture

    Science.gov (United States)

    Kreye, Phillip; Meon, Günter

    2016-04-01

    Complex concepts for the physically correct depiction of dominant processes in the hydrosphere are increasingly at the forefront of hydrological modelling. Many scientific issues in hydrological modelling demand for additional system variables besides a simulation of runoff only, such as groundwater recharge or soil moisture conditions. Models that include soil water simulations are either very simplified or require a high number of parameters. Against this backdrop there is a heightened demand of observations to be used to calibrate the model. A reasonable integration of groundwater data or remote sensing data in calibration procedures as well as the identifiability of physically plausible sets of parameters is subject to research in the field of hydrology. Since this data is often combined with conceptual models, the given interfaces are not suitable for such demands. Furthermore, the application of automated optimisation procedures is generally associated with conceptual models, whose (fast) computing times allow many iterations of the optimisation in an acceptable time frame. One of the main aims of this study is to reduce the discrepancy between scientific and practical applications in the field of hydrological modelling. Therefore, the soil model DYVESOM (DYnamic VEgetation SOil Model) was developed as one of the primary components of the hydrological modelling system PANTA RHEI. DYVESOMs structure provides the required interfaces for the calibrations made at runoff, satellite based soil moisture and groundwater level. The model considers spatial and temporal differentiated feedback of the development of the vegetation on the soil system. In addition, small scale heterogeneities of soil properties (subgrid-variability) are parameterized by variation of van Genuchten parameters depending on distribution functions. Different sets of parameters are operated simultaneously while interacting with each other. The developed soil model is innovative regarding concept

  15. MAGNUM-2D, Heat Transport and Groundwater Flow in Fractured Porous Media

    International Nuclear Information System (INIS)

    Langford, D.W.; Baca, R.G.

    2001-01-01

    1 - Description of program or function: MAGNUM2D was developed to analyze thermally driven fluid motion in the deep basalts below the Paco Basin at the Westinghouse Hanford Site. Has been used in the Basalt Waste Isolation Project to simulate nonisothermal groundwater flow in a heterogeneous anisotropic medium and heat transport in a water-rock system near a high level nuclear waste repository. Allows three representations of the hydrogeologic system: an equivalent porous continuum, a system of discrete, unfilled, and inter- connecting fractures separated by impervious rock mass, and a low permeability porous continuum with several discrete, unfilled fractures traversing the medium. The calculations assume local thermodynamic equilibrium between the rock and groundwater, non- isothermal Darcy flow in the continuum portions of the rock, and nonisothermal Poiseuille flow in discrete unfilled fractures. In addition, the code accounts for thermal loading within the elements, zero normal gradient and fixed boundary conditions for both temperature and hydraulic head, and simulation of the temperature and flow independently. The Q2DGEOM preprocessor was developed to generate, modify, plot and verify quadratic two dimensional finite element geometries. The BCGEN preprocessor generates the boundary conditions for head and temperature and ICGEN generates the initial conditions. The GRIDDER post-processor interpolates non-regularly spaced nodal flow and temperature data onto a regular rectangular grid. CONTOUR plots and labels contour lines for a function of two variables and PARAM plots cross sections and time histories for a function of time and one or two spatial variables. NPRINT generates data tables that display the data along horizontal or vertical cross sections. VELPLT differentiates the hydraulic head and buoyancy data and plots the velocity vectors. The PATH post-processor plots flow paths and computes the corresponding travel times. 2 - Method of solution: MAGNUM2

  16. Numerical simulation of in-situ chemical oxidation (ISCO) and biodegradation of petroleum hydrocarbons using a coupled model for bio-geochemical reactive transport

    Science.gov (United States)

    Marin, I. S.; Molson, J. W.

    2013-05-01

    Petroleum hydrocarbons (PHCs) are a major source of groundwater contamination, being a worldwide and well-known problem. Formed by a complex mixture of hundreds of organic compounds (including BTEX - benzene, toluene, ethylbenzene and xylenes), many of which are toxic and persistent in the subsurface and are capable of creating a serious risk to human health. Several remediation technologies can be used to clean-up PHC contamination. In-situ chemical oxidation (ISCO) and intrinsic bioremediation (IBR) are two promising techniques that can be applied in this case. However, the interaction of these processes with the background aquifer geochemistry and the design of an efficient treatment presents a challenge. Here we show the development and application of BIONAPL/Phreeqc, a modeling tool capable of simulating groundwater flow, contaminant transport with coupled biological and geochemical processes in porous or fractured porous media. BIONAPL/Phreeqc is based on the well-tested BIONAPL/3D model, using a powerful finite element simulation engine, capable of simulating non-aqueous phase liquid (NAPL) dissolution, density-dependent advective-dispersive transport, and solving the geochemical and kinetic processes with the library Phreeqc. To validate the model, we compared BIONAPL/Phreeqc with results from the literature for different biodegradation processes and different geometries, with good agreement. We then used the model to simulate the behavior of sodium persulfate (NaS2O8) as an oxidant for BTEX degradation, coupled with sequential biodegradation in a 2D case and to evaluate the effect of inorganic geochemistry reactions. The results show the advantages of a treatment train remediation scheme based on ISCO and IBR. The numerical performance and stability of the integrated BIONAPL/Phreeqc model was also verified.

  17. Apparent 85Kr ages of groundwater within the Royal watershed, Maine, USA.

    Science.gov (United States)

    Sidle, W C

    2006-01-01

    Specific 85Kr activity is mapped from 264 domestic and municipal wells sampled during 2002-2004 in the Royal watershed (361 km2), Maine. Gas samples are collected at 20 m, 40 m, and > 50 m interval depths within the unconfined aquifers. Gas extraction for 85Kr from wells is obtained directly via a wellhead methodology avoiding conventional collection of large sample volumes. Atmospheric 85Kr input to the recharge environment is estimated at 1.27 Bq m(-3) by time-series analyses of weighted monthly precipitation (2001-2004). Numerical simulation of Kr gas transport through the variable unsaturated zones to the water table suggests up to 12-year time lags locally, thus biasing the 85Kr groundwater ages. Apparent 85Kr ages suggest that approximately 70% of groundwater near 20 m depth was recharged less than 30 years BP (2004). Mass-age transport modeling suggests that post mid-1950s recharge penetrates to part of the basin's floor and that older groundwater seeps from the underlying fractured bedrock may occur.

  18. Modeling dissolution and volatilization of LNAPL sources migrating on the groundwater table.

    Science.gov (United States)

    Kim, Jeongkon; Corapcioglu, M Yavuz

    2003-08-01

    A vertically averaged two-dimensional model was developed to describe areal spreading and migration of light nonaqueous-phase liquids (LNAPLs) introduced into the subsurface by spills or leaks from underground storage tanks. The NAPL transport model was coupled with two-dimensional contaminant transport models to predict contamination of soil gas and groundwater resulting from a LNAPL migrating on the water table. Numerical solutions were obtained by using the finite-difference method. Simulations and sensitivity analyses were conducted with a LNAPL of pure benzene to study LNAPL migration and groundwater contamination. The model was applied to subsurface contamination by jet fuel. Results indicated that LNAPL migration were affected mostly by volatilization. The generation and movement of the dissolved plume was affected by the geology of the site and the free-product plume. Most of the spilled mass remained as a free LNAPL phase 20 years after the spill. The migration of LNAPL for such a long period resulted in the contamination of both groundwater and a large volume of soil.

  19. Three-Dimensional Groundwater Models of the 300 Area at the Hanford Site, Washington State

    Energy Technology Data Exchange (ETDEWEB)

    Williams, Mark D.; Rockhold, Mark L.; Thorne, Paul D.; Chen, Yousu

    2008-09-01

    Researchers at Pacific Northwest National Laboratory developed field-scale groundwater flow and transport simulations of the 300 Area to support the 300-FF-5 Operable Unit Phase III Feasibility Study. The 300 Area is located in the southeast portion of the U.S. Department of Energy’s Hanford Site in Washington State. Historical operations involving uranium fuel fabrication and research activities at the 300 Area have contaminated engineered liquid-waste disposal facilities, the underlying vadose zone, and the uppermost aquifer with uranium. The main objectives of this research were to develop numerical groundwater flow and transport models to help refine the site conceptual model, and to assist assessment of proposed alternative remediation technologies focused on the 300 Area uranium plume.

  20. Natural spatial and temporal variations in groundwater chemistry in fractured, sedimentary rocks: scale and implications for solute transport

    International Nuclear Information System (INIS)

    Hoven, Stephen J. van der; Kip Solomon, D.; Moline, Gerilynn R.

    2005-01-01

    Natural tracers (major ions, δ 18 O, and O 2 ) were monitored to evaluate groundwater flow and transport to a depth of 20 m below the surface in fractured sedimentary (primarily shale and limestone) rocks. Large temporal variations in these tracers were noted in the soil zone and the saprolite, and are driven primarily by individual storm events. During nonstorm periods, an upward flow brings water with high TDS, constant δ 18 O, and low dissolved O 2 to the water table. During storm events, low TDS, variable δ 18 O, and high dissolved O 2 water recharges through the unsaturated zone. These oscillating signals are rapidly transmitted along fracture pathways in the saprolite, with changes occurring on spatial scales of several meters and on a time scale of hours. The variations decreased markedly below the boundary between the saprolite and less weathered bedrock. Variations in the bedrock units occurred on time scales of days and spatial scales of at least 20 m. The oscillations of chemical conditions in the shallow groundwater are hypothesized to have significant implications for solute transport. Solutes and colloids that adsorb onto aquifer solids can be released into solution by decreases in ionic strength and pH. The decreases in ionic strength also cause thermodynamic undersaturation of the groundwater with respect to some mineral species and may result in mineral dissolution. Redox conditions are also changing and may result in mineral dissolution/precipitation. The net result of these chemical variations is episodic transport of a wide range of dissolved solutes or suspended particles, a phenomenon rarely considered in contaminant transport studies

  1. Simulation of the impact of managed aquifer recharge on the groundwater system in Hanoi, Vietnam

    Science.gov (United States)

    Glass, Jana; Via Rico, Daniela A.; Stefan, Catalin; Nga, Tran Thi Viet

    2018-05-01

    A transient numerical groundwater flow model using MODFLOW-NWT was set up and calibrated for Hanoi city, Vietnam, to understand the local groundwater flow system and to suggest solutions for sustainable water resource management. Urban development in Hanoi has caused a severe decline of groundwater levels. The present study evaluates the actual situation and investigates the suitability of managed aquifer recharge (MAR) to stop further depletion of groundwater resources. The results suggest that groundwater is being overexploited, as vast cones of depression exist in parts of the study area. Suitable locations to implement two MAR techniques—riverbank filtration and injection wells—were identified using multi-criteria decision analysis based on geographic information system (GIS). Three predictive scenarios were simulated. The relocation of pumping wells towards the Red River to induce riverbank filtration (first scenario) demonstrates that groundwater levels can be increased, especially in the depression cones. Groundwater levels can also be improved locally by the infiltration of surplus water into the upper aquifer (Holocene) via injection wells during the rainy season (second scenario), but this is not effective to raise the water table in the depression cones. Compared to the first scenario, the combination of riverbank filtration and injection wells (third scenario) shows a slightly raised overall water table. Groundwater flow modeling suggests that local overexploitation can be stopped by a smart relocation of wells from the main depression cones and the expansion of riverbank filtration. This could also avoid further land subsidence while the city's water demand is met.

  2. Death Valley regional groundwater flow system, Nevada and California-Hydrogeologic framework and transient groundwater flow model

    Science.gov (United States)

    Belcher, Wayne R.; Sweetkind, Donald S.

    2010-01-01

    A numerical three-dimensional (3D) transient groundwater flow model of the Death Valley region was developed by the U.S. Geological Survey for the U.S. Department of Energy programs at the Nevada Test Site and at Yucca Mountain, Nevada. Decades of study of aspects of the groundwater flow system and previous less extensive groundwater flow models were incorporated and reevaluated together with new data to provide greater detail for the complex, digital model. A 3D digital hydrogeologic framework model (HFM) was developed from digital elevation models, geologic maps, borehole information, geologic and hydrogeologic cross sections, and other 3D models to represent the geometry of the hydrogeologic units (HGUs). Structural features, such as faults and fractures, that affect groundwater flow also were added. The HFM represents Precambrian and Paleozoic crystalline and sedimentary rocks, Mesozoic sedimentary rocks, Mesozoic to Cenozoic intrusive rocks, Cenozoic volcanic tuffs and lavas, and late Cenozoic sedimentary deposits of the Death Valley regional groundwater flow system (DVRFS) region in 27 HGUs. Information from a series of investigations was compiled to conceptualize and quantify hydrologic components of the groundwater flow system within the DVRFS model domain and to provide hydraulic-property and head-observation data used in the calibration of the transient-flow model. These studies reevaluated natural groundwater discharge occurring through evapotranspiration (ET) and spring flow; the history of groundwater pumping from 1913 through 1998; groundwater recharge simulated as net infiltration; model boundary inflows and outflows based on regional hydraulic gradients and water budgets of surrounding areas; hydraulic conductivity and its relation to depth; and water levels appropriate for regional simulation of prepumped and pumped conditions within the DVRFS model domain. Simulation results appropriate for the regional extent and scale of the model were provided

  3. Fate and Transport of Nutrients in Groundwater and Surface Water in an Urban Slum Catchment Kampala, Uganda

    NARCIS (Netherlands)

    Nyenje, P.

    2014-01-01

    This study investigates the generation, transport and fate of sanitation-related nutrients in groundwater and surface water in an urban slum area in sub-Saharan Africa. In excess, nutrients can cause eutrophication of downstream water bodies. The study argues that nitrogen-containing rains and

  4. Ground-water flow and transport modeling of the NRC-licensed waste disposal facility, West Valley, New York

    International Nuclear Information System (INIS)

    Kool, J.B.; Wu, Y.S.

    1991-10-01

    This report describes a simulation study of groundwater flow and radionuclide transport from disposal at the NRC licensed waste disposal facility in West Valley, New York. A transient, precipitation driven, flow model of the near-surface fractured till layer and underlying unweathered till was developed and calibrated against observed inflow data into a recently constructed interceptor trench for the period March--May 1990. The results suggest that lateral flow through the upper, fractured till layer may be more significant than indicated by previous, steady state flow modeling studies. A conclusive assessment of the actual magnitude of lateral flow through the fractured till could however not be made. A primary factor contributing to this uncertainty is the unknown contribution of vertical infiltration through the interceptor trench cap to the total trench inflow. The second part of the investigation involved simulation of the migration of Sr-90, Cs-137 and Pu-239 from the one of the fuel hull disposal pits. A first-order radionuclide leach rate with rate coefficient of 10 -6 /day was assumed to describe radionuclide release into the disposal pit. The simulations indicated that for wastes buried below the fractured till zone, no significant migration would occur. However, under the assumed conditions, significant lateral migration could occur for radionuclides present in the upper, fractured till zone. 23 refs., 68 figs., 12 tabs

  5. Hydrology and numerical simulation of groundwater flow and streamflow depletion by well withdrawals in the Malad-Lower Bear River Area, Box Elder County, Utah

    Science.gov (United States)

    Stolp, Bernard J.; Brooks, Lynette E.; Solder, John

    2017-03-28

    The Malad-Lower Bear River study area in Box Elder County, Utah, consists of a valley bounded by mountain ranges and is mostly agricultural or undeveloped. The Bear and Malad Rivers enter the study area with a combined average flow of about 1,100,000 acre-feet per year (acre-ft/yr), and this surface water dominates the hydrology. Groundwater occurs in consolidated rock and basin fill. Groundwater recharge occurs from precipitation in the mountains and moves through consolidated rock to the basin fill. Recharge occurs in the valley from irrigation. Groundwater discharge occurs to rivers, springs and diffuse seepage areas, evapotranspiration, field drains, and wells. Groundwater, including springs, is a source for municipal and domestic water supply. Although withdrawal from wells is a small component of the groundwater budget, there is concern that additional groundwater development will reduce the amount of flow in the Malad River. Historical records of surface-water diversions, land use, and groundwater levels indicate relatively stable hydrologic conditions from the 1960s to the 2010s, and that current groundwater development has had little effect on the groundwater system. Average annual recharge to and discharge from the groundwater flow system are estimated to be 164,000 and 228,000 acre-ft/yr, respectively. The imbalance between recharge and discharge represents uncertainties resulting from system complexities, and the possibility of groundwater inflow from surrounding basins.This study reassesses the hydrologic system, refines the groundwater budget, and creates a numerical groundwater flow model that is used to analyze the effects of groundwater withdrawals on surface water. The model uses the detailed catalog of locations and amounts of groundwater recharge and discharge defined during this study. Calibrating the model to adequately simulate recharge, discharge, and groundwater levels results in simulated aquifer properties that can be used to understand

  6. Computer simulation of radial transport in tandem mirror machines

    International Nuclear Information System (INIS)

    Gilmore, J.M.

    1979-01-01

    A code used for simulation of classical radial transport in the 2XIIB experiment has been modified to simulate radial transport in TMX. Results have been obtained using classical transport coefficients and also using very simple trial neoclassical resonant transport coefficients. Comparison of the results obtained with solely classical transport and with both classical and neo-classical transport indicate that neoclassical transport depresses the ion density by approximately 5%. The central cell ion temperature is increased by approximately by the neo-classical transport, as is the electron temperature

  7. URANIUM-SERIES CONSTRAINTS ON RADIONUCLIDE TRANSPORT AND GROUNDWATER FLOW AT NOPAL I URANIUM DEPOSIT, SIERRA PENA BLANCA, MEXICO

    Energy Technology Data Exchange (ETDEWEB)

    S. J. Goldstein, S. Luo, T. L. Ku, and M. T. Murrell

    2006-04-01

    Uranium-series data for groundwater samples from the vicinity of the Nopal I uranium ore deposit are used to place constraints on radionuclide transport and hydrologic processes at this site, and also, by analogy, at Yucca Mountain. Decreasing uranium concentrations for wells drilled in 2003 suggest that groundwater flow rates are low (< 10 m/yr). Field tests, well productivity, and uranium isotopic constraints also suggest that groundwater flow and mixing is limited at this site. The uranium isotopic systematics for water collected in the mine adit are consistent with longer rock-water interaction times and higher uranium dissolution rates at the front of the adit where the deposit is located. Short-lived nuclide data for groundwater wells are used to calculate retardation factors that are on the order of 1,000 for radium and 10,000 to 10,000,000 for lead and polonium. Radium has enhanced mobility in adit water and fractures near the deposit.

  8. URANIUM-SERIES CONSTRAINTS ON RADIONUCLIDE TRANSPORT AND GROUNDWATER FLOW AT NOPAL I URANIUM DEPOSIT, SIERRA PENA BLANCA, MEXICO

    International Nuclear Information System (INIS)

    S. J. Goldstein, S. Luo, T. L. Ku, and M. T. Murrell

    2006-01-01

    Uranium-series data for groundwater samples from the vicinity of the Nopal I uranium ore deposit are used to place constraints on radionuclide transport and hydrologic processes at this site, and also, by analogy, at Yucca Mountain. Decreasing uranium concentrations for wells drilled in 2003 suggest that groundwater flow rates are low (< 10 m/yr). Field tests, well productivity, and uranium isotopic constraints also suggest that groundwater flow and mixing is limited at this site. The uranium isotopic systematics for water collected in the mine adit are consistent with longer rock-water interaction times and higher uranium dissolution rates at the front of the adit where the deposit is located. Short-lived nuclide data for groundwater wells are used to calculate retardation factors that are on the order of 1,000 for radium and 10,000 to 10,000,000 for lead and polonium. Radium has enhanced mobility in adit water and fractures near the deposit

  9. Hydrogeology and simulation of groundwater flow and analysis of projected water use for the Canadian River alluvial aquifer, western and central Oklahoma

    Science.gov (United States)

    Ellis, John H.; Mashburn, Shana L.; Graves, Grant M.; Peterson, Steven M.; Smith, S. Jerrod; Fuhrig, Leland T.; Wagner, Derrick L.; Sanford, Jon E.

    2017-02-13

    This report describes a study of the hydrogeology and simulation of groundwater flow for the Canadian River alluvial aquifer in western and central Oklahoma conducted by the U.S. Geological Survey in cooperation with the Oklahoma Water Resources Board. The report (1) quantifies the groundwater resources of the Canadian River alluvial aquifer by developing a conceptual model, (2) summarizes the general water quality of the Canadian River alluvial aquifer groundwater by using data collected during August and September 2013, (3) evaluates the effects of estimated equal proportionate share (EPS) on aquifer storage and streamflow for time periods of 20, 40, and 50 years into the future by using numerical groundwater-flow models, and (4) evaluates the effects of present-day groundwater pumping over a 50-year period and sustained hypothetical drought conditions over a 10-year period on stream base flow and groundwater in storage by using numerical flow models. The Canadian River alluvial aquifer is a Quaternary-age alluvial and terrace unit consisting of beds of clay, silt, sand, and fine gravel sediments unconformably overlying Tertiary-, Permian-, and Pennsylvanian-age sedimentary rocks. For groundwater-flow modeling purposes, the Canadian River was divided into Reach I, extending from the Texas border to the Canadian River at the Bridgeport, Okla., streamgage (07228500), and Reach II, extending downstream from the Canadian River at the Bridgeport, Okla., streamgage (07228500), to the confluence of the river with Eufaula Lake. The Canadian River alluvial aquifer spans multiple climate divisions, ranging from semiarid in the west to humid subtropical in the east. The average annual precipitation in the study area from 1896 to 2014 was 34.4 inches per year (in/yr).A hydrogeologic framework of the Canadian River alluvial aquifer was developed that includes the areal and vertical extent of the aquifer and the distribution, texture variability, and hydraulic properties of

  10. Groundwater Discharge of Legacy Nitrogen to River Networks: Linking Regional Groundwater Models to Streambed Groundwater-Surface Water Exchange and Nitrogen Processing

    Science.gov (United States)

    Barclay, J. R.; Helton, A. M.; Briggs, M. A.; Starn, J. J.; Hunt, A.

    2017-12-01

    Despite years of management, excess nitrogen (N) is a pervasive problem in many aquatic ecosystems. More than half of surface water in the United States is derived from groundwater, and widespread N contamination in aquifers from decades of watershed N inputs suggest legacy N discharging from groundwater may contribute to contemporary N pollution problems in surface waters. Legacy N loads to streams and rivers are controlled by both regional scale flow paths and fine-scale processes that drive N transformations, such as groundwater-surface water exchange across steep redox gradients that occur at stream bed interfaces. Adequately incorporating these disparate scales is a challenge, but it is essential to understanding legacy N transport and making informed management decisions. We developed a regional groundwater flow model for the Farmington River, a HUC-8 basin that drains to the Long Island Sound, a coastal estuary that suffers from elevated N loads despite decades of management, to understand broad patterns of regional transport. To evaluate and refine the regional model, we used thermal infrared imagery paired with vertical temperature profiling to estimate groundwater discharge at the streambed interface. We also analyzed discharging groundwater for multiple N species to quantify fine scale patterns of N loading and transformation via denitrification at the streambed interface. Integrating regional and local estimates of groundwater discharge of legacy N to river networks should improve our ability to predict spatiotemporal patterns of legacy N loading to and transformation within surface waters.

  11. Estimating the Spatial Distribution of Groundwater Age Using Synoptic Surveys of Environmental Tracers in Streams

    Science.gov (United States)

    Gardner, W. P.

    2017-12-01

    A model which simulates tracer concentration in surface water as a function the age distribution of groundwater discharge is used to characterize groundwater flow systems at a variety of spatial scales. We develop the theory behind the model and demonstrate its application in several groundwater systems of local to regional scale. A 1-D stream transport model, which includes: advection, dispersion, gas exchange, first-order decay and groundwater inflow is coupled a lumped parameter model that calculates the concentration of environmental tracers in discharging groundwater as a function of the groundwater residence time distribution. The lumped parameters, which describe the residence time distribution, are allowed to vary spatially, and multiple environmental tracers can be simulated. This model allows us to calculate the longitudinal profile of tracer concentration in streams as a function of the spatially variable groundwater age distribution. By fitting model results to observations of stream chemistry and discharge, we can then estimate the spatial distribution of groundwater age. The volume of groundwater discharge to streams can be estimated using a subset of environmental tracers, applied tracers, synoptic stream gauging or other methods, and the age of groundwater then estimated using the previously calculated groundwater discharge and observed environmental tracer concentrations. Synoptic surveys of SF6, CFC's, 3H and 222Rn, along with measured stream discharge are used to estimate the groundwater inflow distribution and mean age for regional scale surveys of the Berland River in west-central Alberta. We find that groundwater entering the Berland has observable age, and that the age estimated using our stream survey is of similar order to limited samples from groundwater wells in the region. Our results show that the stream can be used as an easily accessible location to constrain the regional scale spatial distribution of groundwater age.

  12. Isotope hydrology: Investigating groundwater contamination

    International Nuclear Information System (INIS)

    Dubinchuk, V.; Froehlich, K.; Gonfiantini, R.

    1989-01-01

    Groundwater quality has worsened in many regions, with sometimes serious consequences. Decontaminating groundwater is an extremely slow process, and sometimes impossible, because of the generally long residence time of the water in most geological formations. Major causes of contamination are poor groundwater management (often dictated by immediate social needs) and the lack of regulations and control over the use and disposal of contaminants. These types of problems have prompted an increasing demand for investigations directed at gaining insight into the behaviour of contaminants in the hydrological cycle. Major objectives are to prevent pollution and degradation of groundwater resources, or, if contamination already has occurred, to identify its origin so that remedies can be proposed. Environmental isotopes have proved to be a powerful tool for groundwater pollution studies. The IAEA has had a co-ordinated research programme since 1987 on the application of nuclear techniques to determine the transport of contaminants in groundwater. An isotope hydrology project is being launched within the framework of the IAEA's regional co-operative programme in Latin America (known as ARCAL). Main objectives are the application of environmental isotopes to problems of groundwater assessment and contamination in Latin America. In 1989, another co-ordinated research programme is planned under which isotopic and other tracers will be used for the validation of mathematical models in groundwater transport studies

  13. Simulating the effect of water management decisions on groundwater flow and quality in the Kyzylkum Irrigation Scheme, Kazakhstan

    Science.gov (United States)

    Naudascher, R. M.; Marti, B. S.; Siegfried, T.; Wolfgang, K.; Anselm, K.

    2017-12-01

    The Kyzylkum Irrigation Scheme lies north of the Chardara reservoir on the banks of the river Syr Darya in South Kazakhstan. It was designed as a model Scheme and developed to a size of 74'000 ha during Soviet times for rice and cotton production. However, since the 1990s only very limited funds were available for maintenance and as a result, problems like water logging and salinization of soils and groundwater are now omnipresent in the scheme. The aim of this study was to develop a numerical groundwater flow model for the region in Modflow and to evaluate the effect of various infrastructure investments on phreatic evaporation (a major driver for soil salinization). Decadal groundwater observation data from 2011 to 2015 were used to calibrate the annual model and to validate the monthly model. Scenarios simulated were (partial) lining of main and/or secondary and tertiary canal system, improvement of drainage via horizontal canals or pumps, combinations of these and a joint groundwater-surface-water use scenario. Although the annual average model is sufficient to evaluate the yearly water balance, the transient model is a prerequisite for analysing measures against water logging and salinization, both of which feature strong seasonality. The transient simulation shows that a combination of leakage reduction (lining of canals) and drainage improvement measures is needed to lower the groundwater levels enough to avoid phreatic evaporation. To save water, joint surface water and groundwater irrigation can be applied in areas where groundwater salinity is low enough but without proper lining of canals, it is not sufficient to mitigate the ongoing soil degradation due to salinization and water logging.

  14. Simulation of groundwater conditions and streamflow depletion to evaluate water availability in a Freeport, Maine, watershed

    Science.gov (United States)

    Nielsen, Martha G.; Locke, Daniel B.

    2012-01-01

    , the public-supply withdrawals (105.5 million gallons per year (Mgal/yr)) were much greater than those for any other category, being almost 7 times greater than all domestic well withdrawals (15.3 Mgal/yr). Industrial withdrawals in the study area (2.0 Mgal/yr) are mostly by a company that withdraws from an aquifer at the edge of the Merrill Brook watershed. Commercial withdrawals are very small (1.0 Mgal/yr), and no irrigation or other agricultural withdrawals were identified in this study area. A three-dimensional, steady-state groundwater-flow model was developed to evaluate stream-aquifer interactions and streamflow depletion from pumping, to help refine the conceptual model, and to predict changes in streamflow resulting from changes in pumping and recharge. Groundwater levels and flow in the Freeport aquifer study area were simulated with the three-dimensional, finite-difference groundwater-flow modeling code, MODFLOW-2005. Study area hydrology was simulated with a 3-layer model, under steady-state conditions. The groundwater model was used to evaluate changes that could occur in the water budgets of three parts of the local hydrologic system (the Harvey Brook watershed, the Merrill Brook watershed, and the buried aquifer from which pumping occurs) under several different climatic and pumping scenarios. The scenarios were (1) no pumping well withdrawals; (2) current (2009) pumping, but simulated drought conditions (20-percent reduction in recharge); (3) current (2009) recharge, but a 50-percent increase in pumping well withdrawals for public supply; and (4) drought conditions and increased pumping combined. In simulated drought situations, the overall recharge to the buried valley is about 15 percent less and the total amount of streamflow in the model area is reduced by about 19 percent. Without pumping, infiltration to the buried valley aquifer around the confining unit decreased by a small amount (0.05 million gallons per day (Mgal/d)), and discharge to the

  15. Uncertainty Analysis Framework - Hanford Site-Wide Groundwater Flow and Transport Model

    Energy Technology Data Exchange (ETDEWEB)

    Cole, Charles R.; Bergeron, Marcel P.; Murray, Christopher J.; Thorne, Paul D.; Wurstner, Signe K.; Rogers, Phillip M.

    2001-11-09

    Pacific Northwest National Laboratory (PNNL) embarked on a new initiative to strengthen the technical defensibility of the predictions being made with a site-wide groundwater flow and transport model at the U.S. Department of Energy Hanford Site in southeastern Washington State. In FY 2000, the focus of the initiative was on the characterization of major uncertainties in the current conceptual model that would affect model predictions. The long-term goals of the initiative are the development and implementation of an uncertainty estimation methodology in future assessments and analyses using the site-wide model. This report focuses on the development and implementation of an uncertainty analysis framework.

  16. A high-resolution global-scale groundwater model

    Science.gov (United States)

    de Graaf, I. E. M.; Sutanudjaja, E. H.; van Beek, L. P. H.; Bierkens, M. F. P.

    2015-02-01

    Groundwater is the world's largest accessible source of fresh water. It plays a vital role in satisfying basic needs for drinking water, agriculture and industrial activities. During times of drought groundwater sustains baseflow to rivers and wetlands, thereby supporting ecosystems. Most global-scale hydrological models (GHMs) do not include a groundwater flow component, mainly due to lack of geohydrological data at the global scale. For the simulation of lateral flow and groundwater head dynamics, a realistic physical representation of the groundwater system is needed, especially for GHMs that run at finer resolutions. In this study we present a global-scale groundwater model (run at 6' resolution) using MODFLOW to construct an equilibrium water table at its natural state as the result of long-term climatic forcing. The used aquifer schematization and properties are based on available global data sets of lithology and transmissivities combined with the estimated thickness of an upper, unconfined aquifer. This model is forced with outputs from the land-surface PCRaster Global Water Balance (PCR-GLOBWB) model, specifically net recharge and surface water levels. A sensitivity analysis, in which the model was run with various parameter settings, showed that variation in saturated conductivity has the largest impact on the groundwater levels simulated. Validation with observed groundwater heads showed that groundwater heads are reasonably well simulated for many regions of the world, especially for sediment basins (R2 = 0.95). The simulated regional-scale groundwater patterns and flow paths demonstrate the relevance of lateral groundwater flow in GHMs. Inter-basin groundwater flows can be a significant part of a basin's water budget and help to sustain river baseflows, especially during droughts. Also, water availability of larger aquifer systems can be positively affected by additional recharge from inter-basin groundwater flows.

  17. Phase I Contaminant Transport Parameters for the Groundwater Flow and Contaminant Transport Model of Corrective Action Unit 99: Rainier Mesa/Shoshone Mountain, Nevada Test Site, Nye County, Nevada, Revision 1

    Energy Technology Data Exchange (ETDEWEB)

    Nathan Bryant

    2008-05-01

    This document presents a summary and framework of available transport data and other information directly relevant to the development of the Rainier Mesa/Shoshone Mountain (RMSM) Corrective Action Unit (CAU) 99 groundwater transport model. Where appropriate, data and information documented elsewhere are briefly summarized with reference to the complete documentation.

  18. Impacts of urbanization on nitrogen cycling and aerosol, surface and groundwater transport in semi-arid regions

    Science.gov (United States)

    Lohse, K. A.; Gallo, E.; Carlson, M.; Riha, K. M.; Brooks, P. D.; McIntosh, J. C.; Sorooshian, A.; Michalski, G. M.; Meixner, T.

    2011-12-01

    Semi-arid regions are experiencing disproportionate increases in human population and land transformation worldwide, taxing limited water resources and altering nitrogen (N) biogeochemistry. How the redistribution of water and N by urbanization affects semi-arid ecosystems and downstream water quality (e.g. drinking water) is unclear. Understanding these interactions and their feedbacks will be critical for developing science-based management strategies to sustain these limited resources. This is especially true in the US where some of the fastest growing urban areas are in semi-arid ecosystems, where N and water cycles are accelerated, and intimately coupled, and where runoff from urban ecosystems is actively managed to augment a limited water supply to the growing human population. Here we synthesize several ongoing studies from the Tucson Basin in Arizona and examine how increasing urban land cover is altering rainfall-runoff relationships, groundwater recharge, water quality, and long range transport of atmospheric N. Studies across 5 catchments varying in impervious land cover showed that only the least impervious catchment responded to antecedent moisture conditions while hydrologic responses were not statistically related to antecedent rainfall conditions at more impervious sites. Regression models indicated that rainfall depth, imperviousness, and their combined effect control discharge and runoff ratios (p channel characteristics and infrastructure controlled runoff chemistry. Groundwater studies showed nonpoint source contamination of CFCs and associated nitrate in areas of rapid recharge along ephemeral channels. Aerosol measurements indicate that both long-range transport of N and N emissions from Tucson are being transported and deposited at high elevation in areas that recharge regional groundwater. Combined, our findings suggest that urbanization in semi-arid regions results in tradeoffs in the redistribution of water and N that have important

  19. Exposure assessment of groundwater transport of tritium from the Central Nevada Test Area

    International Nuclear Information System (INIS)

    Pohlmann, K.; Chapman, J.; Andricevic, R.

    1995-04-01

    This exposure assessment provides a range of possible human health risk at two locations due to groundwater transport from the Faultless underground nuclear test. These locations correspond to the boundary of the land under DOE control (where no wells currently exist) and the closest existing well (Six Mile Well). The range in excess risk is within the EPA goal for excess risk due to environmental contaminants (10 -6 ) at Six Mile Well. Calculations considering high spatial variability in hydraulic properties and/or high uncertainty in the mean groundwater velocity are also within the EPA goal. At the DOE boundary, the range in excess risk exceeds the EPA goal, regardless of the values of spatial variability and uncertainty. The range in values of excess risk can be reduced with additional field data from the site; however, incorporation of additional data, which would likely be obtained at great expense, is unlikely to result in significant refinement of the results

  20. Groundwater Flow Model of the General Separations Area Using PORFLOW

    International Nuclear Information System (INIS)

    FLACH, GREGORY

    2004-01-01

    The E Area PA (McDowell-Boyer et al. 2000) includes a steady-state simulation of groundwater flow in the General Separations Area as a prerequisite for saturated zone contaminant transport analyses. The groundwater flow simulations are based on the FACT code (Hamm and Aleman2000). The FACT-based GSA model was selected during preparation of the original PA to take advantage of an existing model developed for environmental restoration applications at the SRS (Flach and Harris 1997, 1999; Flach 1999). The existing GSA/FACT model was then slightly modified for PA use, as described in the PA document. FACT is a finite-element code utilizing deformed brick elements. Material properties are defined at element centers, and state variables such as hydraulic head are located at element vertices. The PORFLOW code (Analytic and Computational Research, Inc. 2000) was selected for performing saturated zone transport simulations of source zone radionuclides and their progeny. PORFLOW utilizes control volume discretization and the nodal point integration method, with all properties and state variables being defined at the center of an interior grid cell. The groundwater flow calculation includes translating the Darcy velocity field computed by FACT into a form compatible for input to PORFLOW. The FACT velocity field is defined at element vertices, whereas PORFLOW requires flux across cell faces. For the present PA, PORFLOW cell face flux is computed in a two-step process. An initial face flux is computed from FACT as an average of the normal components of Darcy velocity at the four corners. The derived flux field approximately conserves mass, but not rigorously. Thus, the flux field is subsequently perturbed to force rigorous mass conservation on a cell-by-cell basis. The undocumented process used is non-unique and can introduce significant artifacts into the final flux field

  1. Validation Analysis of the Shoal Groundwater Flow and Transport Model

    Energy Technology Data Exchange (ETDEWEB)

    A. Hassan; J. Chapman

    2008-11-01

    Environmental restoration at the Shoal underground nuclear test is following a process prescribed by a Federal Facility Agreement and Consent Order (FFACO) between the U.S. Department of Energy, the U.S. Department of Defense, and the State of Nevada. Characterization of the site included two stages of well drilling and testing in 1996 and 1999, and development and revision of numerical models of groundwater flow and radionuclide transport. Agreement on a contaminant boundary for the site and a corrective action plan was reached in 2006. Later that same year, three wells were installed for the purposes of model validation and site monitoring. The FFACO prescribes a five-year proof-of-concept period for demonstrating that the site groundwater model is capable of producing meaningful results with an acceptable level of uncertainty. The corrective action plan specifies a rigorous seven step validation process. The accepted groundwater model is evaluated using that process in light of the newly acquired data. The conceptual model of ground water flow for the Project Shoal Area considers groundwater flow through the fractured granite aquifer comprising the Sand Springs Range. Water enters the system by the infiltration of precipitation directly on the surface of the mountain range. Groundwater leaves the granite aquifer by flowing into alluvial deposits in the adjacent basins of Fourmile Flat and Fairview Valley. A groundwater divide is interpreted as coinciding with the western portion of the Sand Springs Range, west of the underground nuclear test, preventing flow from the test into Fourmile Flat. A very low conductivity shear zone east of the nuclear test roughly parallels the divide. The presence of these lateral boundaries, coupled with a regional discharge area to the northeast, is interpreted in the model as causing groundwater from the site to flow in a northeastward direction into Fairview Valley. Steady-state flow conditions are assumed given the absence of

  2. Numerical simulation of advective-dispersive multisolute transport with sorption, ion exchange and equilibrium chemistry

    Science.gov (United States)

    Lewis, F.M.; Voss, C.I.; Rubin, Jacob

    1986-01-01

    A model was developed that can simulate the effect of certain chemical and sorption reactions simultaneously among solutes involved in advective-dispersive transport through porous media. The model is based on a methodology that utilizes physical-chemical relationships in the development of the basic solute mass-balance equations; however, the form of these equations allows their solution to be obtained by methods that do not depend on the chemical processes. The chemical environment is governed by the condition of local chemical equilibrium, and may be defined either by the linear sorption of a single species and two soluble complexation reactions which also involve that species, or binary ion exchange and one complexation reaction involving a common ion. Partial differential equations that describe solute mass balance entirely in the liquid phase are developed for each tenad (a chemical entity whose total mass is independent of the reaction process) in terms of their total dissolved concentration. These equations are solved numerically in two dimensions through the modification of an existing groundwater flow/transport computer code. (Author 's abstract)

  3. A Guide for Using the Transient Ground-Water Flow Model of the Death Valley Regional Ground-Water Flow System, Nevada and California

    Energy Technology Data Exchange (ETDEWEB)

    Joan B. Blainey; Claudia C. Faunt, and Mary C. Hill

    2006-05-16

    This report is a guide for executing numerical simulations with the transient ground-water flow model of the Death Valley regional ground-water flow system, Nevada and California using the U.S. Geological Survey modular finite-difference ground-water flow model, MODFLOW-2000. Model inputs, including observations of hydraulic head, discharge, and boundary flows, are summarized. Modification of the DVRFS transient ground-water model is discussed for two common uses of the Death Valley regional ground-water flow system model: predictive pumping scenarios that extend beyond the end of the model simulation period (1998), and model simulations with only steady-state conditions.

  4. Toward a comprehensive model of chemical transport in porous media

    International Nuclear Information System (INIS)

    Miller, C.W.

    1983-02-01

    A chemical transport model, CHEMTRN, that includes advection, dispersion/diffusion, complexation, sorption, precipitation or dissolution of solids, and the dissociation of water has been written. The transport, mass action and site constraint equations are written in a differential/algebraic form and solved simultaneously. The sorption process is modelled by either ion-exchange or surface complexation. The model has been used to investigate the applicability of a k/sub D/ model for simulating the transport of chemical species in groundwater systems, to simulate precipitation/dissolution of minerals, and to consider the effect of surface complexation on sorption

  5. Comparison of point-source pollutant loadings to soil and groundwater for 72 chemical substances.

    Science.gov (United States)

    Yu, Soonyoung; Hwang, Sang-Il; Yun, Seong-Taek; Chae, Gitak; Lee, Dongsu; Kim, Ki-Eun

    2017-11-01

    Fate and transport of 72 chemicals in soil and groundwater were assessed by using a multiphase compositional model (CompFlow Bio) because some of the chemicals are non-aqueous phase liquids or solids in the original form. One metric ton of chemicals were assumed to leak in a stylized facility. Scenarios of both surface spills and subsurface leaks were considered. Simulation results showed that the fate and transport of chemicals above the water table affected the fate and transport of chemicals below the water table, and vice versa. Surface spill scenarios caused much less concentrations than subsurface leak scenarios because leaching amounts into the subsurface environment were small (at most 6% of the 1 t spill for methylamine). Then, simulation results were applied to assess point-source pollutant loadings to soil and groundwater above and below the water table, respectively, by multiplying concentrations, impact areas, and durations. These three components correspond to the intensity of contamination, mobility, and persistency in the assessment of pollutant loading, respectively. Assessment results showed that the pollutant loadings in soil and groundwater were linearly related (r 2  = 0.64). The pollutant loadings were negatively related with zero-order and first-order decay rates in both soil (r = - 0.5 and - 0.6, respectively) and groundwater (- 1.0 and - 0.8, respectively). In addition, this study scientifically defended that the soil partitioning coefficient (K d ) significantly affected the pollutant loadings in soil (r = 0.6) and the maximum masses in groundwater (r = - 0.9). However, K d was not a representative factor for chemical transportability unlike the expectation in chemical ranking systems of soil and groundwater pollutants. The pollutant loadings estimated using a physics-based hydrogeological model provided a more rational ranking for exposure assessment, compared to the summation of persistency and transportability scores in

  6. In-situ radionuclide transport and preferential groundwater flows at INEEL (Idaho): Decay-series disequilibrium studies

    International Nuclear Information System (INIS)

    Luo, S.; Ku, T.L.; Roback, R.; Murrell, M.; McLing, T.L.

    2000-01-01

    Uranium and thorium-decay series disequilibria in groundwater occur as a result of water-rock interactions, and they provide site-specific, natural analog information for assessment of in-situ, long-term migration of radionuclides in the far field of a nuclear waste disposal site. In this study, a mass balance model was used to relate the decay-series radionuclide distributions among solution, sorbed and solid phases in an aquifer system to processes of water transport, sorption-desorption, dissolution-precipitation, radioactive ingrowth-decay, and α recoil. Isotopes of U and Rn were measured in 23 groundwater samples collected from a basaltic aquifer at the Idaho National Engineering and Environmental Laboratory (INEEL), Idaho. The results show that groundwater activities of Th and Ra isotopes are 2--4 orders lower than those of their U progenitors. Modeling of the observed disequilibria places the following constraints on the time scale of radionuclide migration and water-rock interaction at INEEL: (1) Time for sorption is minutes for Ra and Th; time for desorption is days for Ra and years for Th; and time for precipitation is days for Th, years for Ra, and centuries for U. (2) Retardation factors due to sorption average > 10 6 for 232 Th, approximately10 4 for 226 Ra, and approximately10 3 for 238 U. (3) Dissolution rates of rocks are approximately70 to 800 mg/L/y. (4) Ages of groundwater range from 222 Rn occur near the groundwater recharging sites as well as in the major flow pathways. Decay of the sorbed parent radionuclides (e.g., 226 Ra and 228 Ra) on micro-fracture surfaces constitutes an important source of their daughter ( 222 Rn and 228 Th) activities in groundwater

  7. Uncertainty characteristics of EPA's ground-water transport model for low-level waste performance assessment

    International Nuclear Information System (INIS)

    Yim, Man-Sung

    1995-01-01

    Performance assessment is an essential step either in design or in licensing processes to ensure the safety of any proposed radioactive waste disposal facilities. Since performance assessment requires the use of computer codes, understanding the characteristics of computer models used and the uncertainties of the estimated results is important. The PRESTO-EPA code, which was the basis of the Environmental Protection Agency's analysis for low-level-waste rulemaking, is widely used for various performance assessment activities in the country with no adequate information available for the uncertainty characteristics of the results. In this study, the groundwater transport model PRESTO-EPA was examined based on the analysis of 14 C transport along with the investigation of uncertainty characteristics

  8. Hydrology and phosphorus transport simulation in a lowland polder by a coupled modeling system.

    Science.gov (United States)

    Yan, Renhua; Huang, Jiacong; Li, Lingling; Gao, Junfeng

    2017-08-01

    Modeling the rain-runoff processes and phosphorus transport processes in lowland polders is critical in finding reasonable measures to alleviate the eutrophication problem of downstream rivers and lakes. This study develops a lowland Polder Hydrology and Phosphorus modeling System (PHPS) by coupling the WALRUS-paddy model and an improved phosphorus module of a Phosphorus Dynamic model for lowland Polder systems (PDP). It considers some important hydrological characteristics, such as groundwater-unsaturated zone coupling, groundwater-surface water feedback, human-controlled irrigation and discharge, and detailed physical and biochemical cycles of phosphorus in surface water. The application of the model in the Jianwei polder shows that the simulated phosphorus matches well with the measured values. The high precision of this model combined with its low input data requirement and efficient computation make it practical and easy to the water resources management of Chinese polders. Parameter sensitivity analysis demonstrates that K uptake , c Q2 , c W1 , and c Q1 exert a significant effect on the modeled results, whereas K resuspensionMax , K settling , and K mineralization have little effect on the modeled total phosphorus. Among the three types of uncertainties (i.e., parameter, initial condition, and forcing uncertainties), forcing uncertainty produces the strongest effect on the simulated phosphorus. Based on the analysis result of annual phosphorus balance when considering the high import from irrigation and fertilization, lowland polder is capable of retaining phosphorus and reducing phosphorus export to surrounding aquatic ecosystems because of their special hydrological regulation regime. Copyright © 2016 Elsevier Ltd. All rights reserved.

  9. A flexible hydrological warning system in Denmark for real-time surface water and groundwater simulations

    Science.gov (United States)

    He, Xin; Stisen, Simon; Wiese, Marianne B.; Jørgen Henriksen, Hans

    2015-04-01

    In Denmark, increasing focus on extreme weather events has created considerable demand for short term forecasts and early warnings in relation to groundwater and surface water flooding. The Geological Survey of Denmark and Greenland (GEUS) has setup, calibrated and applied a nationwide water resources model, the DK-Model, primarily for simulating groundwater and surface water flows and groundwater levels during the past 20 years. So far, the DK-model has only been used in offline historical and future scenario simulations. Therefore, challenges arise in operating such a model for online forecasts and early warnings, which requires access to continuously updated observed climate input data and forecast data of precipitation, temperature and global radiation for the next 48 hours or longer. GEUS has a close collaboration with the Danish Meteorological Institute in order to test and enable this data input for the DK model. Due to the comprehensive physical descriptions of the DK-Model, the simulation results can potentially be any component of the hydrological cycle within the models domain. Therefore, it is important to identify which results need to be updated and saved in the real-time mode, since it is not computationally economical to save every result considering the heavy load of data. GEUS have worked closely with the end-users and interest groups such as water planners and emergency managers from the municipalities, water supply and waste water companies, consulting companies and farmer organizations, in order to understand their possible needs for real time simulation and monitoring of the nationwide water cycle. This participatory process has been supported by a web based questionnaire survey, and a workshop that connected the model developers and the users. For qualifying the stakeholder engagement, GEUS has selected a representative catchment area (Skjern River) for testing and demonstrating a prototype of the web based hydrological warning system at the

  10. Geohydrology, geochemistry, and groundwater simulation (1992-2011) and analysis of potential water-supply management options, 2010-60, of the Langford Basin, California

    Science.gov (United States)

    Voronin, Lois M.; Densmore, Jill N.; Martin, Peter; Brush, Charles F.; Carlson, Carl S.; Miller, David M.

    2013-01-01

    Groundwater withdrawals began in 1992 from the Langford Basin within the Fort Irwin National Training Center (NTC), California. From April 1992 to December 2010, approximately 12,300 acre-feet of water (averaging about 650 acre-feet per year) has been withdrawn from the basin and transported to the adjacent Irwin Basin. Since withdrawals began, water levels in the basin have declined by as much as 40 feet, and the quality of the groundwater withdrawn from the basin has deteriorated. The U.S. Geological Survey collected geohydrologic data from Langford Basin during 1992–2011 to determine the quantity and quality of groundwater available in the basin. Geophysical surveys, including gravity, seismic refraction, and time-domain electromagnetic induction surveys, were conducted to determine the depth and shape of the basin, to delineate depths to the Quaternary-Tertiary interface, and to map the depth to the water table and changes in water quality. Data were collected from existing wells and test holes, as well as 11 monitor wells that were installed at 5 sites as part of this study. Water-quality samples collected from wells in the basin were used to determine the groundwater chemistry within the basin and to delineate potential sources of poor-quality groundwater. Analysis of stable isotopes of oxygen and hydrogen in groundwater indicates that present-day precipitation is not a major source of recharge to the basin. Tritium and carbon-14 data indicate that most of the basin was recharged prior to 1952, and the groundwater in the basin has an apparent age of 12,500 to 30,000 years. Recharge to the basin, estimated to be less than 50 acre-feet per year, has not been sufficient to replenish the water that is being withdrawn from the basin. A numerical groundwater-flow model was developed for the Langford Basin to better understand the aquifer system used by the Fort Irwin NTC as part of its water supply, and to provide a tool to help manage groundwater resources at

  11. Numerical simulation of cesium and strontium migration through sodium bentonite altered by cation exchange with groundwater components

    International Nuclear Information System (INIS)

    Jacobsen, J.S.; Carnahan, C.L.

    1988-10-01

    Numerical simulations have been used to investigate how spatial and temporal changes in the ion exchange properties of bentonite affect the migration of cationic fission products from high-level waste. Simulations in which fission products compete for exchange sites with ions present in groundwater diffusing into the bentonite are compared to simulations in which the exchange properties of bentonite are constant. 12 refs., 3 figs., 2 tabs

  12. Simulated effects of impoundment of lake seminole on ground-water flow in the upper Floridan Aquifer in southwestern Georgia and adjacent parts of Alabama and Florida

    Science.gov (United States)

    Jones, L. Elliott; Torak, Lynn J.

    2004-01-01

    Hydrologic implications of the impoundment of Lake Seminole in southwest Georgia and its effect on components of the surface- and ground-water flow systems of the lower Apalachicola?Chattahoochee?Flint (ACF) River Basin were investigated using a ground-water model. Comparison of simulation results of postimpoundment drought conditions (October 1986) with results of hypothetical preimpoundment conditions (a similar drought prior to 1955) provides a qualitative measure of the changes in hydraulic head and ground-water flow to and from streams and Lake Seminole, and across State lines caused by the impoundment. Based on the simulation results, the impoundment of Lake Seminole changed ground-water flow directions within about 20?30 miles of the lake, reducing the amount of ground water flowing from Florida to Georgia southeast of the lake. Ground-water storage was increased by the impoundment, as indicated by a simulated increase of as much as 26 feet in the water level in the Upper Floridan aquifer. The impoundment of Lake Seminole caused changes to simulated components of the ground-water budget, including reduced discharge from the Upper Floridan aquifer to streams (315 million gallons per day); reduced recharge from or increased discharge to regional ground-water flow at external model boundaries (totaling 183 million gallons per day); and reduced recharge from or increased discharge to the undifferentiated overburden (totaling 129 million gallons per day).

  13. Contaminant Transport Parameters for the Groundwater Flow and Contaminant Transport Model of Corrective Action Units 101 and 102: Central and Western Pahute Mesa, Nye County, Nevada, Revision 0

    Energy Technology Data Exchange (ETDEWEB)

    Drici, Warda [International Technologies Corporation, Las Vegas, NV (United States)

    2003-08-01

    This report documents the analysis of the available transport parameter data conducted in support of the development of a Corrective Action Unit (CAU) groundwater flow model for Central and Western Pahute Mesa: CAUs 101 and 102.

  14. Groundwater recharge - climatic and vegetation induced variations. Simulations in the Emaan and Aespoe areas in southern Sweden

    International Nuclear Information System (INIS)

    Losjoe, K.; Johansson, Barbro; Bringfelt, B.; Oleskog, I.; Bergstroem, S.

    1999-01-01

    Climate change and man-made interference will cause an impact on runoff and groundwater recharge in the future. With the aim to give a conception of seasonal variations and the magnitude of the differences, the HBV model has been used as a tool for simulating five climate alternatives in two areas of south-east Sweden. The climate alternatives include both increased and decreased temperature and precipitation. These are not predictions of a future climate change, and should only be regarded as examples. The purpose has been to exemplify a conceivable magnitude of change during temperate/boreal conditions. It has not been within the scope of this report to evaluate the most probable climate change scenarios. The impacts of different climate scenarios on the total groundwater recharge and the deep groundwater recharge have been calculated as long-term mean values and are presented in comparison with model-simulated values with an actual (recorded) climate sequence. The results show great differences between the climate alternatives. An increase in temperature will decrease snow accumulation and increase the evapotranspiration and can totally extinguish the spring snowmelt peak in runoff and groundwater recharge. A decreased temperature, on the contrary, will imply decreased winter runoff and recharge values and an increase in spring and summer values. Evapotranspiration and soil water content play a key role in the runoff and recharge processes. This report makes a review of some literature about work done within the areas of investigation and calculation of evapotranspiration. Research is in progress, not only on formulating future climate scenarios, but also on distinguishing evapotranspiration from different kinds of vegetation. These are complex questions, but vital ones, as a climate change will also affect the vegetation. Until new research results are presented, well-known methods can be used for simulating the effects of logging on runoff and groundwater

  15. Simulation of shallow groundwater levels: Comparison of a data-driven and a conceptual model

    Science.gov (United States)

    Fahle, Marcus; Dietrich, Ottfried; Lischeid, Gunnar

    2015-04-01

    Despite an abundance of models aimed at simulating shallow groundwater levels, application of such models is often hampered by a lack of appropriate input data. Difficulties especially arise with regard to soil data, which are typically hard to obtain and prone to spatial variability, eventually leading to uncertainties in the model results. Modelling approaches relying entirely on easily measured quantities are therefore an alternative to encourage the applicability of models. We present and compare two models for calculating 1-day-ahead predictions of the groundwater level that are only based on measurements of potential evapotranspiration, precipitation and groundwater levels. The first model is a newly developed conceptual model that is parametrized using the White method (which estimates the actual evapotranspiration on basis of diurnal groundwater fluctuations) and a rainfall-response ratio. Inverted versions of the two latter approaches are then used to calculate the predictions of the groundwater level. Furthermore, as a completely data-driven alternative, a simple feed-forward multilayer perceptron neural network was trained based on the same inputs and outputs. Data of 4 growing periods (April to October) from a study site situated in the Spreewald wetland in North-east Germany were taken to set-up the models and compare their performance. In addition, response surfaces that relate model outputs to combinations of different input variables are used to reveal those aspects in which the two approaches coincide and those in which they differ. Finally, it will be evaluated whether the conceptual approach can be enhanced by extracting knowledge of the neural network. This is done by replacing in the conceptual model the default function that relates groundwater recharge and groundwater level, which is assumed to be linear, by the non-linear function extracted from the neural network.

  16. Uncertainty of simulated groundwater levels arising from stochastic transient climate change scenarios

    Science.gov (United States)

    Goderniaux, Pascal; Brouyère, Serge; Blenkinsop, Stephen; Burton, Aidan; Fowler, Hayley; Dassargues, Alain

    2010-05-01

    The evaluation of climate change impact on groundwater reserves represents a difficult task because both hydrological and climatic processes are complex and difficult to model. In this study, we present an innovative methodology that combines the use of integrated surface - subsurface hydrological models with advanced stochastic transient climate change scenarios. This methodology is applied to the Geer basin (480 km²) in Belgium, which is intensively exploited to supply the city of Liège (Belgium) with drinking water. The physically-based, spatially-distributed, surface-subsurface flow model has been developed with the finite element model HydroGeoSphere . The simultaneous solution of surface and subsurface flow equations in HydroGeoSphere, as well as the internal calculation of the actual evapotranspiration as a function of the soil moisture at each node of the evaporative zone, enables a better representation of interconnected processes in all domains of the catchment (fully saturated zone, partially saturated zone, surface). Additionally, the use of both surface and subsurface observed data to calibrate the model better constrains the calibration of the different water balance terms. Crucially, in the context of climate change impacts on groundwater resources, the evaluation of groundwater recharge is improved. . This surface-subsurface flow model is combined with advanced climate change scenarios for the Geer basin. Climate change simulations were obtained from six regional climate model (RCM) scenarios assuming the SRES A2 greenhouse gases emission (medium-high) scenario. These RCM scenarios were statistically downscaled using a transient stochastic weather generator technique, combining 'RainSim' and the 'CRU weather generator' for temperature and evapotranspiration time series. This downscaling technique exhibits three advantages compared with the 'delta change' method usually used in groundwater impact studies. (1) Corrections to climate model output are

  17. High performance stream computing for particle beam transport simulations

    International Nuclear Information System (INIS)

    Appleby, R; Bailey, D; Higham, J; Salt, M

    2008-01-01

    Understanding modern particle accelerators requires simulating charged particle transport through the machine elements. These simulations can be very time consuming due to the large number of particles and the need to consider many turns of a circular machine. Stream computing offers an attractive way to dramatically improve the performance of such simulations by calculating the simultaneous transport of many particles using dedicated hardware. Modern Graphics Processing Units (GPUs) are powerful and affordable stream computing devices. The results of simulations of particle transport through the booster-to-storage-ring transfer line of the DIAMOND synchrotron light source using an NVidia GeForce 7900 GPU are compared to the standard transport code MAD. It is found that particle transport calculations are suitable for stream processing and large performance increases are possible. The accuracy and potential speed gains are compared and the prospects for future work in the area are discussed

  18. Effects of macropores on groundwater flow and transport of radionuclides

    International Nuclear Information System (INIS)

    Huff, D.D.; DeAngelis, D.L.; Yeh, G.T.

    1983-01-01

    In humid environments, recent findings have shown that an important component of runoff and associated solute moves rapidly through large continuous voids. Thus, consideration of radionuclide transport in subsurface flow is incomplete without explicit treatment of continuous macropores and interaction between macropore flow and the soil matrix. A computer model, FRACPORT, that simulates the transport of a solute through a fractured porous matrix has been developed. The model employs the Integrated Compartment Method and uses the approach of dividing the porous media into compartments comprising fractures or porous material. The fracture region and a small portion of the porous matrix are simulated using a shorter time step than for the remaining porous matrix. This allows substantial savings in computational time. The model should be useful for analyses of generic problems associated with water and radionuclide transport in macropore systems at shallow-land disposal sites in humid environments. 14 references, 6 figures, 1 table

  19. Impacts of Groundwater on the Atmospheric Convection in Amazon using Multi-GCM Simulations from I-GEM project

    Science.gov (United States)

    Lo, M. H.; Chien, R. Y.; Ducharne, A.; Decharme, B.; Lan, C. W.; Wang, F.; Cheruy, F.; Colin, J.

    2017-12-01

    Previous research indicated that groundwater plays an important role in hydrological cycle and is a major source of water vapor in climate models, which may result in modifications of atmospheric convection. For instance, our previous study showed that when considering the groundwater dynamics in a GCM, the wet soil induced surface cooling effect can further reduce the Amazon dry season convection and precipitation. However, the main mechanisms of the interaction among groundwater, soil moisture, and precipitation are still unclear, and they need to be examined in several climate models. In this study, we further examine the influence of the surface cooling effects due to the groundwater on the convection over the Amazon. To this end, we use idealized simulations of the IGEM (Impact of Groundwater in Earth system Models) project, with 3 GCMs (CESM, CNRM, and IPSL): in each of them, we prescribed a water table at a constant depth throughout all land areas, to create globally wet conditions. Preliminary analysis shows a contradict result of the tendency of precipitation in the three models with wet condition which indicates a great uncertainty of the groundwater's impacts in coupled GCMs.

  20. Imaging geochemical heterogeneities using inverse reactive transport modeling: An example relevant for characterizing arsenic mobilization and distribution

    DEFF Research Database (Denmark)

    Fakhreddine, Sarah; Lee, Jonghyun; Kitanidis, Peter K.

    2016-01-01

    groundwater parameters. Specifically, we simulate the mobilization of arsenic via kinetic oxidative dissolution of As-bearing pyrite due to dissolved oxygen in the ambient groundwater, which is an important mechanism for arsenic release in groundwater both under natural conditions and engineering applications......The spatial distribution of reactive minerals in the subsurface is often a primary factor controlling the fate and transport of contaminants in groundwater systems. However, direct measurement and estimation of heterogeneously distributed minerals are often costly and difficult to obtain. While...

  1. Transport simulations TFTR: Theoretically-based transport models and current scaling

    International Nuclear Information System (INIS)

    Redi, M.H.; Cummings, J.C.; Bush, C.E.; Fredrickson, E.; Grek, B.; Hahm, T.S.; Hill, K.W.; Johnson, D.W.; Mansfield, D.K.; Park, H.; Scott, S.D.; Stratton, B.C.; Synakowski, E.J.; Tang, W.M.; Taylor, G.

    1991-12-01

    In order to study the microscopic physics underlying observed L-mode current scaling, 1-1/2-d BALDUR has been used to simulate density and temperature profiles for high and low current, neutral beam heated discharges on TFTR with several semi-empirical, theoretically-based models previously compared for TFTR, including several versions of trapped electron drift wave driven transport. Experiments at TFTR, JET and D3-D show that I p scaling of τ E does not arise from edge modes as previously thought, and is most likely to arise from nonlocal processes or from the I p -dependence of local plasma core transport. Consistent with this, it is found that strong current scaling does not arise from any of several edge models of resistive ballooning. Simulations with the profile consistent drift wave model and with a new model for toroidal collisionless trapped electron mode core transport in a multimode formalism, lead to strong current scaling of τ E for the L-mode cases on TFTR. None of the theoretically-based models succeeded in simulating the measured temperature and density profiles for both high and low current experiments

  2. IMPACTS OF ROAD DE-ICING SALTS ON MANGANESE TRANSPORT TO GROUNDWATER IN ROADSIDE SOILS

    OpenAIRE

    Wen, Yingrong

    2012-01-01

    Manganese (Mn) is an important element in soil, it occur natural in minerals and precipitated as Mn-oxides. Several factors could decide the solubility and mobility of Mn in soil water. In this study, the impact of road de-icing salts (NaCl) on manganese mobilization and transport to groundwater in roadside soils has been investigated by leaching tests. Generally, in the salt solution leachates, the water-soluble concentrations of Mn tended to increase with elevated salt concentrations, sugge...

  3. Application of SELECT and SWAT models to simulate source load, fate, and transport of fecal bacteria in watersheds.

    Science.gov (United States)

    Ranatunga, T.

    2017-12-01

    Modeling of fate and transport of fecal bacteria in a watershed is a processed based approach that considers releases from manure, point sources, and septic systems. Overland transport with water and sediments, infiltration into soils, transport in the vadose zone and groundwater, die-off and growth processes, and in-stream transport are considered as the other major processes in bacteria simulation. This presentation will discuss a simulation of fecal indicator bacteria source loading and in-stream conditions of a non-tidal watershed (Cedar Bayou Watershed) in South Central Texas using two models; Spatially Explicit Load Enrichment Calculation Tool (SELECT) and Soil and Water Assessment Tool (SWAT). Furthermore, it will discuss a probable approach of bacteria source load reduction in order to meet the water quality standards in the streams. The selected watershed is listed as having levels of fecal indicator bacteria that posed a risk for contact recreation and wading by the Texas Commission of Environmental Quality (TCEQ). The SELECT modeling approach was used in estimating the bacteria source loading from land categories. Major bacteria sources considered were, failing septic systems, discharges from wastewater treatment facilities, excreta from livestock (Cattle, Horses, Sheep and Goat), excreta from Wildlife (Feral Hogs, and Deer), Pet waste (mainly from Dogs), and runoff from urban surfaces. The estimated source loads from SELECT model were input to the SWAT model, and simulate the bacteria transport through the land and in-stream. The calibrated SWAT model was then used to estimate the indicator bacteria in-stream concentrations for future years based on regional land use, population and household forecast (up to 2040). Based on the reductions required to meet the water quality standards in-stream, the corresponding required source load reductions were estimated.

  4. Simulation of Groundwater Movement for Nuclear Research Center at AlTuwaitha Area in Baghdad City, Iraq

    Directory of Open Access Journals (Sweden)

    Ayad Sleibi Mustafa

    2017-07-01

    Full Text Available The simulation of groundwater movement has been carried out by using MODFLOW model in order to show the impact of change of water surface elevation of the Tigris river on layers of the aquifer system for Nuclear Research Center at Al-Tuwaitha area, in addition to evaluate the ability of the proposed pumping well to collect groundwater and change the direction of flow at steady-state. The results of the study indicated that there is a good match between the values of groundwater levels that calculated in the model and measured in the field, where mean error is 0.09 m.The study also showed that the increasing of water surface elevation of the Tigris river led to increase in the hydraulic head of observed wells, while the use proposed pumping well reduced the hydraulic head and intercepted the movement of groundwater flow. The flow direction is toward the Tigris river, and the velocity of flow is clear in the third layer identified medium sand which is 0.0015 m/day. The using of the proposed pumping well has changed the direction of groundwater, especially in the area around the well.

  5. Global gyrokinetic simulation of tokamak transport

    International Nuclear Information System (INIS)

    Furnish, G.; Horton, W.; Kishimoto, Y.; LeBrun, M.J.; Tajima, T.

    1998-10-01

    A kinetic simulation code based on the gyrokinetic ion dynamics in global general metric (including a tokamak with circular or noncircular cross-section) has been developed. This gyrokinetic simulation is capable of examining the global and semi-global driftwave structures and their associated transport in a tokamak plasma. The authors investigate the property of the ion temperature gradient (ITG) or η i (η i ≡ ∂ ell nT i /∂ ell n n i ) driven drift waves in a tokamak plasma. The emergent semi-global drift wave modes give rise to thermal transport characterized by the Bohm scaling

  6. What Drives Saline Circulation Cells in Coastal Aquifers? An Energy Balance for Density-Driven Groundwater Systems

    Science.gov (United States)

    Harvey, C. F.; Michael, H. A.

    2017-12-01

    We formulate the energy balance for coastal groundwater systems and apply it to: (1) Explain the energy driving offshore saline circulation cells, and; (2) Assess the accuracy of numerical simulations of coastal groundwater systems. The flow of fresh groundwater to the ocean is driven by the loss of potential energy as groundwater drops from the elevation of the inland watertable, where recharge occurs, to discharge at sea level. This freshwater flow creates an underlying circulation cell of seawater, drawn into coastal aquifers offshore and discharging near shore, that adds to total submarine groundwater discharge. The saline water in the circulation cell enters and exits the aquifer through the sea floor at the same hydraulic potential. Existing theory explains that the saline circulation cell is driven by mixing of fresh and saline without any additional source of potential or mechanical power. This explanation raises a basic thermodynamic question: what is the source of energy that drives the saline circulation cell? Here, we resolve this question by building upon Hubbert's conception of hydraulic potential to formulate an energy balance for density-dependent flow and salt transport through an aquifer. We show that, because local energy dissipation within the aquifer is proportional to the square of the groundwater velocity, more groundwater flow may be driven through an aquifer for a given energy input if local variations in velocity are smoothed. Our numerical simulations of coastal groundwater systems show that dispersion of salt across the fresh-saline interface spreads flow over larger volumes of the aquifer, smoothing the velocity field, and increasing total flow and submarine groundwater discharge without consuming more power. The energy balance also provides a criterion, in addition to conventional mass balances, for judging the accuracy of numerical solutions of non-linear density-dependent flow problems. Our results show that some numerical

  7. Ground-water hydrology and simulation of ground-water flow at Operable Unit 3 and surrounding region, U.S. Naval Air Station, Jacksonville, Florida

    Science.gov (United States)

    Davis, J.H.

    1998-01-01

    conductivity in the intermediate layer, determined from one aquifer test, is 20 feet per day. An extensive stormwater drainage system is present at OU3 and the surrounding area. Some of the stormwater drains have been documented to be draining ground water from the upper layer of the surficial aquifer, whereas other drains are only suspected to be draining ground water. The subregional model contained 78 rows and 148 columns of square model cells that were 100 feet on each side. Vertically, the surficial aquifer was divided into two layers; layer 1 represented the upper layer and layer 2 represented the intermediate layer. Steady-state ground-water flow conditions were assumed. The model was calibrated to head data collected on October 29 and 30, 1996. After calibration, the model matched all 67 measured heads to within the calibration criterion of 1 foot; and 48 of 67 simulated heads (72 percent) were within 0.5 foot. Model simulated recharge rates ranged from 0.4 inch per year in areas that were largely paved to 13.0 inches per year in irrigated areas. Simulated hydraulic conductivities in the upper layer at OU3 ranged from 0.5 foot per day in the north to 1.0 foot per day in the south. Simulated vertical leakance between the upper and intermediate layers ranged from 1.0x10-6 per day in an area with low-permeability clays to 4.3x10-2 per day in an area that had been dredged. Simulated transmissivities in the intermediate layer ranged from 25 feet squared per day in an area of low-permeability channel-fill deposits to a high of 1,200 feet squared per day in areas covering most of OU3. Simulated riverbed conductances ranged from 4 to 60 feet squared per day and simulated bottom conductances of leaking stormwater drains ranged from 5 to 20 feet squared per day. The direction and velocity of ground-water flow was determined using particle-tracking techniques. Ground-water flow in the upper layer was generally eastward toward the St. Johns River. However, leaking stormwat

  8. Simulation of a low energy beam transport line

    International Nuclear Information System (INIS)

    Yang Yao; Liu Zhanwen; Zhang Wenhui; Ma Hongyi; Zhang Xuezhen; Zhao Hongwei; Yao Ze'en

    2012-01-01

    A 2.45 GHz electron cyclotron resonance intense proton source and a low energy beam transport line with dual-Glaser lens were designed and fabricated by Institute of Modern Physics for a compact pulsed hadron source at Tsinghua. The intense proton beams extracted from the ion source are transported through the transport line to match the downstream radio frequency quadrupole accelerator. Particle-in-cell code BEAMPATH was used to carry out the beam transport simulations and optimize the magnetic field structures of the transport line. Emittance growth due to space charge and spherical aberrations of the Glaser lens were studied in both theory and simulation. The results show that narrow beam has smaller aberrations and better beam quality through the transport line. To better match the radio frequency quadrupole accelerator, a shorter transport line is desired with sufficient space charge neutralization. (authors)

  9. FACT (Version 2.0) - Subsurface Flow and Contaminant Transport Documentation and User's Guide

    Energy Technology Data Exchange (ETDEWEB)

    Aleman, S.E.

    2000-05-05

    This report documents a finite element code designed to model subsurface flow and contaminant transport, named FACT. FACT is a transient three-dimensional, finite element code designed to simulate isothermal groundwater flow, moisture movement, and solute transport in variably saturated and fully saturated subsurface porous media.

  10. Validation on groundwater flow model including sea level change. Modeling on groundwater flow in coastal granite area

    International Nuclear Information System (INIS)

    Hasegawa, Takuma; Miyakawa, Kimio

    2009-01-01

    It is important to verify the groundwater flow model that reproduces pressure head, water chemistry, and groundwater age. However, water chemistry and groundwater age are considered to be influenced by historical events. In this study, sea level change during glacial-interglacial cycle was taken into account for simulating salinity and groundwater age at coastal granite area. As a result of simulation, salinity movement could not catch up with sea level changes, and mixing zone was formed below the fresh-water zone. This mixing zone was observed in the field measurement, and the observed salinities were agreed with simulated results including sea level change. The simulated residence time including sea level change is one-tenth of steady state. The reason is that the saline water was washed out during regression and modern sea-water was infiltrated during transgression. As mentioned before, considering sea level change are important to reproduce salinity and helium age at coastal area. (author)

  11. Groundwater sustainability and groundwater/surface-water interaction in arid Dunhuang Basin, northwest China

    Science.gov (United States)

    Lin, Jingjing; Ma, Rui; Hu, Yalu; Sun, Ziyong; Wang, Yanxin; McCarter, Colin P. R.

    2018-03-01

    The Dunhuang Basin, a typical inland basin in northwestern China, suffers a net loss of groundwater and the occasional disappearance of the Crescent Lake. Within this region, the groundwater/surface-water interactions are important for the sustainability of the groundwater resources. A three-dimensional transient groundwater flow model was established and calibrated using MODFLOW 2000, which was used to predict changes to these interactions once a water diversion project is completed. The simulated results indicate that introducing water from outside of the basin into the Shule and Danghe rivers could reverse the negative groundwater balance in the Basin. River-water/groundwater interactions control the groundwater hydrology, where river leakage to the groundwater in the Basin will increase from 3,114 × 104 m3/year in 2017 to 11,875 × 104 m3/year in 2021, and to 17,039 × 104 m3/year in 2036. In comparison, groundwater discharge to the rivers will decrease from 3277 × 104 m3/year in 2017 to 1857 × 104 m3/year in 2021, and to 510 × 104 m3/year by 2036; thus, the hydrology will switch from groundwater discharge to groundwater recharge after implementing the water diversion project. The simulation indicates that the increased net river infiltration due to the water diversion project will raise the water table and then effectively increasing the water level of the Crescent Lake, as the lake level is contiguous with the water table. However, the regional phreatic evaporation will be enhanced, which may intensify soil salinization in the Dunhuang Basin. These results can guide the water allocation scheme for the water diversion project to alleviate groundwater depletion and mitigate geo-environmental problem.

  12. Baseline groundwater model update for p-area groundwater operable unit, NBN

    Energy Technology Data Exchange (ETDEWEB)

    Ross, J. [Savannah River Site (SRS), Aiken, SC (United States); Amidon, M. [Savannah River Site (SRS), Aiken, SC (United States)

    2015-09-01

    This report documents the development of a numerical groundwater flow and transport model of the hydrogeologic system of the P-Area Reactor Groundwater Operable Unit at the Savannah River Site (SRS) (Figure 1-1). The P-Area model provides a tool to aid in understanding the hydrologic and geochemical processes that control the development and migration of the current tritium, tetrachloroethene (PCE), and trichloroethene (TCE) plumes in this region.

  13. Transport and fate of organic wastes in groundwater at the Stringfellow hazardous waste disposal site, southern California

    Science.gov (United States)

    Leenheer, J.A.; Hsu, J.; Barber, L.B.

    2001-01-01

    In January 1999, wastewater influent and effluent from the pretreatment plant at the Stringfellow hazardous waste disposal site were sampled along with groundwater at six locations along the groundwater contaminant plume. The objectives of this sampling and study were to identify at the compound class level the unidentified 40-60% of wastewater organic contaminants, and to determine what organic compound classes were being removed by the wastewater pretreatment plant, and what organic compound classes persisted during subsurface waste migration. The unidentified organic wastes are primarily chlorinated aromatic sulfonic acids derived from wastes from DDT manufacture. Trace amounts of EDTA and NTA organic complexing agents were discovered along with carboxylate metabolites of the common alkylphenolpolyethoxylate plasticizers and nonionic surfactants. The wastewater pretreatment plant removed most of the aromatic chlorinated sulfonic acids that have hydrophobic neutral properties, but the p-chlorobenzenesulfonic acid which is the primary waste constituent passed through the pretreatment plant and was discharged in the treated wastewaters transported to an industrial sewer. During migration in groundwater, p-chlorobenzenesulfonic acid is removed by natural remediation processes. Wastewater organic contaminants have decreased 3- to 45-fold in the groundwater from 1985 to 1999 as a result of site remediation and natural remediation processes. The chlorinated aromatic sulfonic acids with hydrophobic neutral properties persist and have migrated into groundwater that underlies the adjacent residential community. Copyright ?? 2001 .

  14. Modeling the impact of the nitrate contamination on groundwater at the groundwater body scale : The Geer basin case study (Invited)

    Science.gov (United States)

    Brouyere, S.; Orban, P.; Hérivaux, C.

    2009-12-01

    In the next decades, groundwater managers will have to face regional degradation of the quantity and quality of groundwater under pressure of land-use and socio-economic changes. In this context, the objectives of the European Water Framework Directive require that groundwater be managed at the scale of the groundwater body, taking into account not only all components of the water cycle but also the socio-economic impact of these changes. One of the main challenges remains to develop robust and efficient numerical modeling applications at such a scale and to couple them with economic models, as a support for decision support in groundwater management. An integrated approach between hydrogeologists and economists has been developed by coupling the hydrogeological model SUFT3D and a cost-benefit economic analysis to study the impact of agricultural practices on groundwater quality and to design cost-effective mitigation measures to decrease nitrate pressure on groundwater so as to ensure the highest benefit to the society. A new modeling technique, the ‘Hybrid Finite Element Mixing Cell’ approach has been developed for large scale modeling purposes. The principle of this method is to fully couple different mathematical and numerical approaches to solve groundwater flow and solute transport problems. The mathematical and numerical approaches proposed allows an adaptation to the level of local hydrogeological knowledge and the amount of available data. In combination with long time series of nitrate concentrations and tritium data, the regional scale modelling approach has been used to develop a 3D spatially distributed groundwater flow and solute transport model for the Geer basin (Belgium) of about 480 km2. The model is able to reproduce the spatial patterns of nitrate concentrations together nitrate trends with time. The model has then been used to predict the future evolution of nitrate trends for two types of scenarios: (i) a “business as usual scenario

  15. Virus in Groundwater: Characterization of transport mechanisms and impacts on an agricultural area in Uruguay

    Science.gov (United States)

    Gamazo, P. A.; Colina, R.; Victoria, M.; Alvareda, E.; Burutaran, L.; Ramos, J.; Lopez, F.; Soler, J.

    2014-12-01

    In many areas of Uruguay groundwater is the only source of water for human consumption and for industrial-agricultural economic activities. Traditionally considered as a safe source, due to the "natural filter" that occurs in porous media, groundwater is commonly used without any treatment. The Uruguayan law requires bacteriological analysis for most water uses, but virological analyses are not mentioned in the legislation. In the Salto district, where groundwater is used for human consumption and for agricultural activities, bacterial contamination has been detected in several wells but no viruses analysis have been performed. The Republic University (UDELAR), with the support of the National Agency for Research and Innovation (ANII), is studying the incidence of virus in groundwater on an intensive agriculture area of the Salto district. In this area water is pumped from the "Salto Aquifer", a free sedimentary aquifer. Below this sedimentary deposit is the "Arapey" basaltic formation, which is also exploited for water productions on its fractured zones. A screening campaign has been performed searching for bacterial and viral contamination. Total and fecal coliforms have been found on several wells and Rotavirus and Adenovirus have been detected. A subgroup of the screening wells has been selected for an annual survey. On this subgroup, besides bacteria and viruses analysis, a standard physical and chemical characterization was performed. Results show a significant seasonal variation on microbiological contamination. In addition to field studies, rotavirus circulation experiments on columns are being performed. The objective of this experiments is to determinate the parameters that control virus transport in porous media. The results of the study are expected to provide an insight into the impacts of groundwater on Salto's viral gastroenterocolitis outbreaks.

  16. Death Valley regional ground-water flow system, Nevada and California -- hydrogeologic framework and transient ground-water flow model

    Science.gov (United States)

    Belcher, Wayne R.

    2004-01-01

    A numerical three-dimensional (3D) transient ground-water flow model of the Death Valley region was developed by the U.S. Geological Survey for the U.S. Department of Energy programs at the Nevada Test Site and at Yucca Mountain, Nevada. Decades of study of aspects of the ground-water flow system and previous less extensive ground-water flow models were incorporated and reevaluated together with new data to provide greater detail for the complex, digital model. A 3D digital hydrogeologic framework model (HFM) was developed from digital elevation models, geologic maps, borehole information, geologic and hydrogeologic cross sections, and other 3D models to represent the geometry of the hydrogeologic units (HGUs). Structural features, such as faults and fractures, that affect ground-water flow also were added. The HFM represents Precambrian and Paleozoic crystalline and sedimentary rocks, Mesozoic sedimentary rocks, Mesozoic to Cenozoic intrusive rocks, Cenozoic volcanic tuffs and lavas, and late Cenozoic sedimentary deposits of the Death Valley Regional Ground-Water Flow System (DVRFS) region in 27 HGUs. Information from a series of investigations was compiled to conceptualize and quantify hydrologic components of the ground-water flow system within the DVRFS model domain and to provide hydraulic-property and head-observation data used in the calibration of the transient-flow model. These studies reevaluated natural ground-water discharge occurring through evapotranspiration and spring flow; the history of ground-water pumping from 1913 through 1998; ground-water recharge simulated as net infiltration; model boundary inflows and outflows based on regional hydraulic gradients and water budgets of surrounding areas; hydraulic conductivity and its relation to depth; and water levels appropriate for regional simulation of prepumped and pumped conditions within the DVRFS model domain. Simulation results appropriate for the regional extent and scale of the model were

  17. Mathematical modeling and evaluation of radionuclide transport parameters from the ANL Laboratory Analog Program

    International Nuclear Information System (INIS)

    Chen, B.C.J.; Hull, J.R.; Seitz, M.G.; Sha, W.T.; Shah, V.L.; Soo, S.L.

    1984-07-01

    Computer model simulation is required to evaluate the performance of proposed or future high-level radioactive waste geological repositories. However, the accuracy of a model in predicting the real situation depends on how well the values of the transport properties are prescribed as input parameters. Knowledge of transport parameters is therefore essential. We have modeled ANL's Experiment Analog Program which was designed to simulate long-term radwaste migration process by groundwater flowing through a high-level radioactive waste repository. Using this model and experimental measurements, we have evaluated neptunium (actinide) deposition velocity and analyzed the complex phenomena of simultaneous deposition, erosion, and reentrainment of bentonite when groundwater is flowing through a narrow crack in a basalt rock. The present modeling demonstrates that we can obtain the values of transport parameters, as added information without any additional cost, from the available measurements of laboratory analog experiments. 8 figures, 3 tables

  18. Transport of radionuclides by bentonite and silica colloids in a GR-3 synthetic groundwater-interim report

    International Nuclear Information System (INIS)

    Ames, L.L.; McGarrah, J.E.; Walker, B.A.

    1983-08-01

    Radionuclide distributions in groundwater-colloid-basalt systems were measured using GR-3 groundwater and crushed Umtanum basalt at 60 degree C. The objective was to estimate the potential for radionuclide transport from a nuclear waste repository in basalt by colloids suspended in groundwater. Three colloids were studied -- a bentonite colloid representing a potential component of packing or backfill materials in the repository, and two hydrated silica colloids which might represent those generated from a glass waste form. The radioelements studied included isotopes of neptunium, uranium, selenium, technetium, and radium. Measurements of radionuclide distributions in experiments with the bentonite colloid showed that uranium was sorbed strongly on the colloid (under both oxidizing and reducing conditions) but was readily transferred to basalt when it was added to the system. Sorption of neptunium, technetium, and selenium on the colloid was greatly enhanced by using reducing conditions. Only small amounts of neptunium and technetium were transferred to the basalt under reducing conditions, but most of the selenium was readily transferred under these conditions

  19. A proposed strategy for the validation of ground-water flow and solute transport models

    International Nuclear Information System (INIS)

    Davis, P.A.; Goodrich, M.T.

    1991-01-01

    Ground-water flow and transport models can be thought of as a combination of conceptual and mathematical models and the data that characterize a given system. The judgment of the validity or invalidity of a model depends both on the adequacy of the data and the model structure (i.e., the conceptual and mathematical model). This report proposes a validation strategy for testing both components independently. The strategy is based on the philosophy that a model cannot be proven valid, only invalid or not invalid. In addition, the authors believe that a model should not be judged in absence of its intended purpose. Hence, a flow and transport model may be invalid for one purpose but not invalid for another. 9 refs

  20. The combined use of MODFLOW and precipitation-runoff modeling to simulate groundwater flow in a diffuse-pollution prone watershed.

    Science.gov (United States)

    Elçi, A; Karadaş, D; Fistikoğlu, O

    2010-01-01

    A numerical modeling case study of groundwater flow in a diffuse pollution prone area is presented. The study area is located within the metropolitan borders of the city of Izmir, Turkey. This groundwater flow model was unconventional in the application since the groundwater recharge parameter in the model was estimated using a lumped, transient water-budget based precipitation-runoff model that was executed independent of the groundwater flow model. The recharge rate obtained from the calibrated precipitation-runoff model was used as input to the groundwater flow model, which was eventually calibrated to measured water table elevations. Overall, the flow model results were consistent with field observations and model statistics were satisfactory. Water budget results of the model revealed that groundwater recharge comprised about 20% of the total water input for the entire study area. Recharge was the second largest component in the budget after leakage from streams into the subsurface. It was concluded that the modeling results can be further used as input for contaminant transport modeling studies in order to evaluate the vulnerability of water resources of the study area to diffuse pollution.

  1. Characterizing the Occurrence and Transport of Brackish Groundwater in Southwest Bangladesh

    Science.gov (United States)

    worland, S.; Hornberger, G. M.

    2013-12-01

    Bangladesh is host to the largest and the most active delta system in the world. The morphology of the southern part of the country is characterized by low lying deltaic plains partitioned by the distributary networks of the Ganges, Brahmaputra and Meghna river systems. Much of the tidal mangrove forest ecosystem of the lower delta has been converted into poldered islands that sustain shrimp farming and rice production. The polder inhabitants depend on shallow groundwater as a primary source for drinking water and sanitation. Understanding the origin and hydrologic controls on the distribution of the brackish water and freshwater on the polder is a necessary step to ensuring a sustainable and potable freshwater source for drinking and irrigation. Preliminary sampling from shallow tube wells on Polder 32 in southwest Bangladesh suggests sporadic lateral apportioning of fresh water in the primarily brackish aquifer. This research characterizes the occurrence, transport and fate of the brackish groundwater through a combination of 3H and 14C dating, geochemical signatures, subsurface mapping using inversions from electromagnetic induction, and a 1D finite difference model and a 2D finite element model. The geochemical analysis and radiometric dating suggest that the salt water originates from paleo-brackish estuarine water deposited ~5000 years ago along with the sediments that compose the shallow aquifer. Inversions of electromagnetic survey data show potential freshwater recharge areas where the clay cap pinches out. The finite difference model demonstrates that recharge from the distributary channels is unlikely due to the low transmissivity of the clay channel beds. The finite element model gives reasonable estimates of the flushing rates of the connate brackish water beneath the polder. Inversion of electromagnetic data from a two hundred meter transect taken on Polder 32 Head gradient and groundwater flow vectors for fixed head boundary conditions across Polder

  2. Use of Short Chained Alkylphenols (SCAP in Analysis of Transport Behaviour of Oil Contaminated Groundwater

    Directory of Open Access Journals (Sweden)

    M. Sauter

    2002-06-01

    Full Text Available Shortchained alkylphenols (SCAP represent a main constituent of crude oil and coal liquefaction products. Due to their specific oil/water partitioning behaviour and high aqueous solubility they can be detected in oil exploitation waters and groundwaters affected by various spills near oil pipelines, oil exploitation sites and coal liquefaction plants. New efficient and powerful analytical techniques have been developed that allow the identification of all 34 individual compounds (C0-C3 without derivatisation and in complex matrices. Due to the different physico-chemical properties of the SCAP, differential transport behaviour in groundwater can be observed, changing the relative concentrations of SCAP downgradient in space and time. These characteristic ratios can be employed to derive information on migration direction and the ageing of the source of contamination. A case study is presented to illustrate the use of this new tool.

  3. Hydrologic assessment and numerical simulation of groundwater flow, San Juan Mine, San Juan County, New Mexico, 2010–13

    Science.gov (United States)

    Stewart, Anne M.

    2018-04-03

    Coal combustion byproducts (CCBs), which are composed of fly ash, bottom ash, and flue gas desulfurization material, produced at the coal-fired San Juan Generating Station (SJGS), located in San Juan County, New Mexico, have been buried in former surface-mine pits at the San Juan Mine, also referred to as the San Juan Coal Mine, since operations began in the early 1970s. This report, prepared by the U.S. Geological Survey in cooperation with the Mining and Minerals Division of the New Mexico Energy, Minerals and Natural Resources Department, describes results of a hydrogeologic assessment, including numerical groundwater modeling, to identify the timing of groundwater recovery and potential pathways for groundwater transport of metals that may be leached from stored CCBs and reach hydrologic receptors after operations cease. Data collected for the hydrologic assessment indicate that groundwater in at least one centrally located reclaimed surface-mining pit has already begun to recover.The U.S. Geological Survey numerical modeling package MODFLOW–NWT was used with MODPATH particle-tracking software to identify advective flow paths from CCB storage areas toward potential hydrologic receptors. Results indicate that groundwater at CCB storage areas will recover to the former steady state, or in some locations, groundwater may recover to a new steady state in 6,600 to 10,600 years at variable rates depending on the proximity to a residual cone-of-groundwater depression caused by mine dewatering and regional oil and gas pumping as well as on actual, rather than estimated, groundwater recharge and evapotranspirational losses. Advective particle-track modeling indicates that the number of particles and rates of advective transport will vary depending on hydraulic properties of the mine spoil, particularly hydraulic conductivity and porosity. Modeling results from the most conservative scenario indicate that particles can migrate from CCB repositories to either the

  4. The Science of Transportation Analysis and Simulation

    Science.gov (United States)

    Gleibe, John

    2010-03-01

    Transportation Science focuses on methods developed to model and analyze the interaction between human behavior and transportation systems. From the human behavioral, or demand, perspective, we are interested in how person and households organize their activities across space and time, with travel viewed as an enabling activity. We have a particular interest in how to model the range of responses to public policy and transportation system changes, which leads to the consideration of both short- and long-term decision-making, interpersonal dependencies, and non-transportation-related opportunities and constraints, including household budgets, land use systems and economic systems. This has led to the development of complex structural econometric modeling systems as well as agent-based simulations. From the transportation systems, or supply, perspective we are interested in the level of service provide by transportation facilities, be it auto, transit or multi-modal systems. This has led to the development of network models and equilibrium concepts as well as hybrid simulation systems based on concepts borrowed from physics, such as fluid flow models, and cellular automata-type models. In this presentation, we review a representative sample of these methods and their use in transportation planning and public policy analysis.

  5. Simulated effects of projected ground-water withdrawals in the Floridan aquifer system, greater Orlando metropolitan area, east-central Florida

    Science.gov (United States)

    Murray, Louis C.; Halford, Keith J.

    1999-01-01

    Ground-water levels in the Floridan aquifer system within the greater Orlando metropolitan area are expected to decline because of a projected increase in the average pumpage rate from 410 million gallons per day in 1995 to 576 million gallons per day in 2020. The potential decline in ground-water levels and spring discharge within the area was investigated with a calibrated, steady-state, ground-water flow model. A wetter-than-average condition scenario and a drought-condition scenario were simulated to bracket the range of water-levels and springflow that may occur in 2020 under average rainfall conditions. Pumpage used to represent the drought-condition scenario totaled 865 million gallons per day, about 50 percent greater than the projected average pumpage rate in 2020. Relative to average 1995 steady-state conditions, drawdowns simulated in the Upper Floridan aquifer exceeded 10 and 25 feet for wet and dry conditions, respectively, in parts of central and southwest Orange County and in north Osceola County. In Seminole County, drawdowns of up to 20 feet were simulated for dry conditions, compared with 5 to 10 feet simulated for wet conditions. Computed springflow was reduced by 10 percent for wet conditions and by 38 percent for dry conditions, with the largest reductions (28 and 76 percent) occurring at the Sanlando Springs group. In the Lower Floridan aquifer, drawdowns simulated in southwest Orange County exceeded 20 and 40 feet for wet and dry conditions, respectively.

  6. Geostatistical simulation of geological architecture and uncertainty propagation in groundwater modeling

    DEFF Research Database (Denmark)

    He, Xiulan

    parameters and model structures, which are the primary focuses of this PhD research. Parameter uncertainty was analyzed using an optimization tool (PEST: Parameter ESTimation) in combination with a random sampling method (LHS: Latin Hypercube Sampling). Model structure, namely geological architecture...... be compensated by model parameters, e.g. when hydraulic heads are considered. However, geological structure is the primary source of uncertainty with respect to simulations of groundwater age and capture zone. Operational MPS based software has been on stage for just around ten years; yet, issues regarding...... geological structures of these three sites provided appropriate conditions for testing the methods. Our study documented that MPS is an efficient approach for simulating geological heterogeneity, especially for non-stationary system. The high resolution of geophysical data such as SkyTEM is valuable both...

  7. Assessment of ground-water flow and chemical transport in a tidally influenced aquifer using geostatistical filtering and hydrocarbon fingerprinting

    International Nuclear Information System (INIS)

    Marquis, S.A. Jr.; Smith, E.A.

    1994-01-01

    Traditional environmental investigations at tidally influenced hazardous waste sites such as marine fuel storage terminals have generally failed to characterize ground-water flow and chemical transport because they have been based on only a cursory knowledge of plume geometry, chemicals encountered, and hydrogeologic setting and synoptic ground-water level measurement. Single-time observations cannot be used to accurately determine flow direction and gradient in tidally fluctuating aquifers since these measurements delineate hydraulic head at only one point in time during a tidal cycle, not the net effect of the fluctuations. In this study, a more rigorous approach was used to characterize flow and chemical transport in a tidally influenced aquifer at a marine fuel storage terminal using: (1) ground-water-level monitoring over three tidal cycles (72 hours), (2) geostatistical filtering of ground-water-level data using 25-hour and 71-hour filtering methods, and (3) hydrocarbon fingerprinting analysis. The results from the study indicate that naphtha released from one of the on-site naphtha tanks has been the predominant contributor to the hydrocarbon plume both on-site and downgradient off-site and that net ground-water and hydrocarbon movement has been to the southeast away from the tank since 1989

  8. Biological transportation networks: Modeling and simulation

    KAUST Repository

    Albi, Giacomo

    2015-09-15

    We present a model for biological network formation originally introduced by Cai and Hu [Adaptation and optimization of biological transport networks, Phys. Rev. Lett. 111 (2013) 138701]. The modeling of fluid transportation (e.g., leaf venation and angiogenesis) and ion transportation networks (e.g., neural networks) is explained in detail and basic analytical features like the gradient flow structure of the fluid transportation network model and the impact of the model parameters on the geometry and topology of network formation are analyzed. We also present a numerical finite-element based discretization scheme and discuss sample cases of network formation simulations.

  9. Transient Conditions at the Ice/bed Interface Under a Palaeo-ice Stream Derived from Numerical Simulation of Groundwater Flow and Sedimentological Observations in a Drumlin Field, NW Poland

    Science.gov (United States)

    Hermanowski, P.; Piotrowski, J. A.

    2017-12-01

    Evacuation of glacial meltwater through the substratum is an important agent modulating the ice/bed interface processes. The amount of meltwater production, subglacial water pressure, flow patterns and fluxes all affect the strength of basal coupling and thus impact the ice-sheet dynamics. Despite much research into the subglacial processes of past ice sheets which controlled sediment transport and the formation of specific landforms, our understanding of the ice/bed interface remains fragmentary. In this study we numerically simulated, using finite difference and finite element codes, groundwater flow pattern and fluxes during an ice advance in the Stargard Drumlin Field, NW Poland to examine the potential influence of groundwater drainage on the landforming processes. The results are combined with sedimentological observations of the internal composition of the drumlins to validate the outcome of the numerical model. Our numerical experiments of groundwater flow suggest a highly time-dependent response of the subglacial hydrogeological system to the advancing ice margin. This is manifested as diversified areas of downward- and upward-oriented groundwater flows whereby the drumlin field area experienced primarily groundwater discharge towards the ice sole. The investigated drumlins are composed of (i) mainly massive till with thin stringers of meltwater sand, and (ii) sorted sediments carrying ductile deformations. The model results and sedimentological observations suggest a high subglacial pore-water pressure in the drumlin field area, which contributed to sediment deformation intervening with areas of basal decoupling and enhanced basal sliding.

  10. Transient simulation of groundwater levels within a sandbar of the Colorado River, Marble Canyon, Arizona, 2004

    Science.gov (United States)

    Sabol, Thomas A.; Springer, Abraham E.

    2013-01-01

    Seepage erosion and mass failure of emergent sandy deposits along the Colorado River in Grand Canyon National Park, Arizona, are a function of the elevation of groundwater in the sandbar, fluctuations in river stage, the exfiltration of water from the bar face, and the slope of the bar face. In this study, a generalized three-dimensional numerical model was developed to predict the time-varying groundwater level, within the bar face region of a freshly deposited eddy sandbar, as a function of river stage. Model verification from two transient simulations demonstrates the ability of the model to predict groundwater levels within the onshore portion of the sandbar face across a range of conditions. Use of this generalized model is applicable across a range of typical eddy sandbar deposits in diverse settings. The ability to predict the groundwater level at the onshore end of the sandbar face is essential for both physical and numerical modeling efforts focusing on the erosion and mass failure of eddy sandbars downstream of Glen Canyon Dam along the Colorado River.

  11. Simulation of ground-water flow in the St. Peter aquifer in an area contaminated by coal-tar derivatives, St. Louis Park, Minnesota. Water Resources Investigation

    International Nuclear Information System (INIS)

    Lorenz, D.L.; Stark, J.R.

    1990-01-01

    A model constructed to simulate ground-water flow in part of the Prairie du Chien-Jordan and St. Peter aquifers, St. Louis Park, Minnesota, was used to test hypotheses about the movement of ground water contaminated with coal-tar derivatives and to simulate alternatives for reducing the downgradient movement of contamination in the St. Peter aquifer. The model, constructed for a previous study, was applied to simulate the effects of current ground-water withdrawals on the potentiometric surface of the St. Peter aquifer. Model simulations predict that the multiaquifer wells have the potential to limit downgradient migration of contaminants in the St. Peter aquifer caused by cones of depression created around the multiaquifer wells. Differences in vertical leakage to the St. Peter aquifer may exist in areas of bedrock valleys. Model simulations indicate that these differences are not likely to affect significantly the general patterns of ground-water flow

  12. Approaches to groundwater travel time

    International Nuclear Information System (INIS)

    Kaplan, P.; Klavetter, E.; Peters, R.

    1989-01-01

    One of the objectives of performance assessment for the Yucca Mountain Project is to estimate the groundwater travel time at Yucca Mountain, Nevada, to determine whether the site complies with the criteria specified in the Code of Federal Regulations, Title 10 CFR 60.113 (a). The numerical standard for performance in these criteria is based on the groundwater travel time along the fastest path of likely radionuclide transport from the disturbed zone to the accessible environment. The concept of groundwater travel time as proposed in the regulations, does not have a unique mathematical statement. The purpose of this paper is to discuss the ambiguities associated with the regulatory specification of groundwater travel time, two different interpretations of groundwater travel time, and the effect of the two interpretations on estimates of the groundwater travel time

  13. PATHS groundwater hydrologic model

    Energy Technology Data Exchange (ETDEWEB)

    Nelson, R.W.; Schur, J.A.

    1980-04-01

    A preliminary evaluation capability for two-dimensional groundwater pollution problems was developed as part of the Transport Modeling Task for the Waste Isolation Safety Assessment Program (WISAP). Our approach was to use the data limitations as a guide in setting the level of modeling detail. PATHS Groundwater Hydrologic Model is the first level (simplest) idealized hybrid analytical/numerical model for two-dimensional, saturated groundwater flow and single component transport; homogeneous geology. This document consists of the description of the PATHS groundwater hydrologic model. The preliminary evaluation capability prepared for WISAP, including the enhancements that were made because of the authors' experience using the earlier capability is described. Appendixes A through D supplement the report as follows: complete derivations of the background equations are provided in Appendix A. Appendix B is a comprehensive set of instructions for users of PATHS. It is written for users who have little or no experience with computers. Appendix C is for the programmer. It contains information on how input parameters are passed between programs in the system. It also contains program listings and test case listing. Appendix D is a definition of terms.

  14. Characterization of groundwater flow in the environment of the Boom Clay (Campine, Belgium)

    International Nuclear Information System (INIS)

    Gedeon, M.; Labat, S.; Wemaere, I.; Wouters, L.

    2010-01-01

    -east of Belgium. The North-eastern Belgium model (NEB-2002) represents the second update of previous regional models of the north-eastern Belgium aquifer system for the reference site at Mol-Dessel dating from 1984 and 1992. It aimed at modelling the groundwater system both above and below the Boom Clay. Since the groundwater regimes differ substantially above and below the Boom Clay, the modelling results were conceptually divided into one representing the original and one representing the evolving state of the aquifers below the Boom Clay. This division was based on existence of excessive pumping of the aquifers below the Boom Clay that has caused continuous decrease of the groundwater levels during the last 50 years. Since such transient situation occurs in the aquifers below the Boom Clay a steady-state model cannot be used to describe the long-term equilibrium of the aquifer system. The Deep aquifer pumping model (DAP model) focuses on the transient behaviour of the confined parts of the aquifers located below the Boom Clay. The aim of the model was to reconstruct the history of pumping in the aquifers below the Boom Clay and fit the simulated heads to the observed values. It is, of course, impossible to precisely predict the evolution towards the future; however, the results indicate a possible extent of hydraulic gradient change induced by pumping. The Neogene aquifer model (NAM model) simulates the groundwater flow in the aquifers above the Boom Clay. The NAM model is enclosed by the natural no-flow boundaries of the river catchments. The Nete catchment is simulated with two principal rivers: Kleine Nete and Grote Nete rivers. The modelled area is smaller in respect to the NEB-2002 model, which allows more detailed schematization. The vertical division of the Neogene aquifer model allows for later incorporation of a more detailed scale model simulating transport of radionuclide contamination. The NAM model is numerically optimised to overcome the problem of

  15. Gyrokinetic particle simulation of neoclassical transport

    International Nuclear Information System (INIS)

    Lin, Z.; Tang, W.M.; Lee, W.W.

    1995-01-01

    A time varying weighting (δf ) scheme for gyrokinetic particle simulation is applied to a steady-state, multispecies simulation of neoclassical transport. Accurate collision operators conserving momentum and energy are developed and implemented. Simulation results using these operators are found to agree very well with neoclassical theory. For example, it is dynamically demonstrated that like-particle collisions produce no particle flux and that the neoclassical fluxes are ambipolar for an ion--electron plasma. An important physics feature of the present scheme is the introduction of toroidal flow to the simulations. Simulation results are in agreement with the existing analytical neoclassical theory. The poloidal electric field associated with toroidal mass flow is found to enhance density gradient-driven electron particle flux and the bootstrap current while reducing temperature gradient-driven flux and current. Finally, neoclassical theory in steep gradient profile relevant to the edge regime is examined by taking into account finite banana width effects. In general, in the present work a valuable new capability for studying important aspects of neoclassical transport inaccessible by conventional analytical calculation processes is demonstrated. copyright 1995 American Institute of Physics

  16. Development of suitability maps for ground-coupled heat pump systems using groundwater and heat transport models

    Energy Technology Data Exchange (ETDEWEB)

    Fujii, Hikari; Itoi, Ryuichi [Department of Earth Resources Engineering, Faculty of Engineering, Kyushu University, Motooka 744, Nishi-ku, Fukuoka 819-0395 (Japan); Inatomi, Tadasuke [YBM Co. Ltd., Kishiyama 589-10 Kitahata, Karatsu 847-1211 (Japan); Uchida, Youhei [Geological Survey of Japan, AIST Tsukuba Central 7, Tsukuba 305-8567 (Japan)

    2007-10-15

    The thermophysical properties of subsurface materials (soils, sediments and rocks) and groundwater flow strongly affect the heat exchange rates of ground heat exchangers (GHEs). These rates can be maximized and the installation costs of the ground-coupled heat pump (GCHP) systems reduced by developing suitability maps based on local geological and hydrological information. Such maps were generated for the Chikushi Plain (western Japan) using field-survey data and a numerical modeling study. First, a field-wide groundwater model was developed for the area and the results matched against measured groundwater levels and vertical temperature profiles. Single GHE models were then constructed to simulate the heat exchange performance at different locations in the plain. Finally, suitability maps for GCHP systems were prepared using the results from the single GHE models. Variations in the heat exchange rates of over 40% revealed by the map were ascribed to differences in the GHE locations, confirming how important it is to use appropriate thermophysical data when designing GCHP systems. (author)

  17. Simulating the effects of ground-water withdrawals on streamflow in a precipitation-runoff model

    Science.gov (United States)

    Zarriello, Philip J.; Barlow, P.M.; Duda, P.B.

    2004-01-01

    Precipitation-runoff models are used to assess the effects of water use and management alternatives on streamflow. Often, ground-water withdrawals are a major water-use component that affect streamflow, but the ability of surface-water models to simulate ground-water withdrawals is limited. As part of a Hydrologic Simulation Program-FORTRAN (HSPF) precipitation-runoff model developed to analyze the effect of ground-water and surface-water withdrawals on streamflow in the Ipswich River in northeastern Massachusetts, an analytical technique (STRMDEPL) was developed for calculating the effects of pumped wells on streamflow. STRMDEPL is a FORTRAN program based on two analytical solutions that solve equations for ground-water flow to a well completed in a semi-infinite, homogeneous, and isotropic aquifer in direct hydraulic connection to a fully penetrating stream. One analytical method calculates unimpeded flow at the stream-aquifer boundary and the other method calculates the resistance to flow caused by semipervious streambed and streambank material. The principle of superposition is used with these analytical equations to calculate time-varying streamflow depletions due to daily pumping. The HSPF model can readily incorporate streamflow depletions caused by a well or surface-water withdrawal, or by multiple wells or surface-water withdrawals, or both, as a combined time-varying outflow demand from affected channel reaches. These demands are stored as a time series in the Watershed Data Management (WDM) file. This time-series data is read into the model as an external source used to specify flow from the first outflow gate in the reach where these withdrawals are located. Although the STRMDEPL program can be run independently of the HSPF model, an extension was developed to run this program within GenScn, a scenario generator and graphical user interface developed for use with the HSPF model. This extension requires that actual pumping rates for each well be stored

  18. Estimating Groundwater Development area in Jianan Plain using Standardized Groundwater Index

    Science.gov (United States)

    Yu, Chang Hsiang; Haw, Lee Cheng

    2017-04-01

    Taiwan has been facing severe water crises in recent years owing to the effects of extreme weather conditions. Changes in precipitation patterns have also made the drought phenomenon increasingly prominent, which has indirectly affected groundwater recharge. Hence, in the present study, long-term monitoring data were collected from the study area of the Jianan plain. The standardized groundwater index (SGI) and was then used to analyse the region's drought characteristics. To analyse the groundwater level by using SGI, making SGI180 groundwater level be the medium water crises, and SGI360 groundwater level be the extreme water crises. Through the different water crises signal in SGI180 and SGI360, we divide groundwater in Jianan plain into two sections. Thereby the water crises indicators establishing groundwater level standard line in Jianan Plain, then using the groundwater level standard line to find the study area where could be groundwater development area in Jianan plain. Taking into account relatively more water scarcity in dry season, so the study screen out another emergency backup groundwater development area, but the long-term groundwater development area is still as a priority development area. After finding suitable locations, groundwater modeling systems(GMS) software is used to simulate our sites to evaluate development volume. Finally, the result of study will help the government to grasp the water shortage situation immediately and solve the problem of water resources deployment.

  19. Oxygen transport properties estimation by DSMC-CT simulations

    Energy Technology Data Exchange (ETDEWEB)

    Bruno, Domenico [Istituto di Metodologie Inorganiche e dei Plasmi, Consiglio Nazionale delle Ricerche - Via G. Amendola, 122 - 70125 Bari (Italy); Frezzotti, Aldo; Ghiroldi, Gian Pietro [Dipartimento di Scienze e Tecnologie Aerospaziali, Politecnico di Milano - Via La Masa, 34 - 20156 Milano (Italy)

    2014-12-09

    Coupling DSMC simulations with classical trajectories calculations is emerging as a powerful tool to improve predictive capabilities of computational rarefied gas dynamics. The considerable increase of computational effort outlined in the early application of the method (Koura,1997) can be compensated by running simulations on massively parallel computers. In particular, GPU acceleration has been found quite effective in reducing computing time (Ferrigni,2012; Norman et al.,2013) of DSMC-CT simulations. The aim of the present work is to study rarefied Oxygen flows by modeling binary collisions through an accurate potential energy surface, obtained by molecular beams scattering (Aquilanti, et al.,1999). The accuracy of the method is assessed by calculating molecular Oxygen shear viscosity and heat conductivity following three different DSMC-CT simulation methods. In the first one, transport properties are obtained from DSMC-CT simulations of spontaneous fluctuation of an equilibrium state (Bruno et al, Phys. Fluids, 23, 093104, 2011). In the second method, the collision trajectory calculation is incorporated in a Monte Carlo integration procedure to evaluate the Taxman’s expressions for the transport properties of polyatomic gases (Taxman,1959). In the third, non-equilibrium zero and one-dimensional rarefied gas dynamic simulations are adopted and the transport properties are computed from the non-equilibrium fluxes of momentum and energy. The three methods provide close values of the transport properties, their estimated statistical error not exceeding 3%. The experimental values are slightly underestimated, the percentage deviation being, again, few percent.

  20. The role of colloids in the transport of radioelements by groundwater

    International Nuclear Information System (INIS)

    Skytte Jensen, B.; Halken, T.

    1993-01-01

    An unsettled problem in migration studies is to what extent do colloids take part in the transport of elements with flowing groundwater. Numerous experimental studies have clearly demonstrated that colloids are able to adsorb traces of foreign elements including the actinide ions present in solution, and simple models adequate for the specific experimental conditions may be established. There are, however, not enough data available to model the overall behaviour of 'colloid-complexes' under highly variable natural conditions, where competition for adsorption and flocculation phenomena complicate the simple models. It is the intention of the present project to perform experiments directed at obtaining the missing information and secondly to establish a model, if possible, which may be used for predictive purposes. 3 refs., 4 figs., 5 tabs

  1. Groundwater evolution of the granite area, Korea

    International Nuclear Information System (INIS)

    Kim, C.S.; Bae, D.S.; Koh, Y.K.; Kim, K.S.; Kim, G.Y.

    2001-01-01

    The geochemistry and environmental isotopes of groundwater in the Cretaceous granite of the Yeongcheon area has been investigated. The hydrochemistry of groundwater belongs to the Ca-HCO 3 type. The oxygen-18 and deuterium data are clustered along the meteoric water line, indicating that the groundwater is of meteoric water origin. Tritium data show that the groundwaters were mostly recharged before pre-thermonuclear period and have been mixed with younger surface water flowing rapidly along fractured zones. Based on the mass balance and reaction simulation approaches using both the hydrochemistry of groundwater and the secondary mineralogy of fracture-filling materials, the low-temperature hydrogeochemical evolution of groundwater in the area has been modeled. The results of geochemical simulation show that the concentrations of Ca, Na and HCO 3 and pH of waters increase progressively owing to the dissolution of reactive minerals in flow paths. The concentrations of Mg and K first increase with the dissolution of reactant minerals, but later decrease when montmorillonite and illitic material are precipitated respectively. The continuous adding of reactive minerals, i. e. the progressively larger degrees of water/rock interaction, causes the formation of secondary minerals with the following sequence: hematite > gibbsite > kaolinite > montmorillonite > illitic material > microcline. The results of reaction simulation agree well with the observed water chemistry and secondary mineralogy, indicating the successful applicability of this simulation technique to delineate the complex hydrogeochemistry of bedrock groundwaters. (author)

  2. Reexamining ultrafiltration and solute transport in groundwater

    Science.gov (United States)

    Neuzil, C. E.; Person, Mark

    2017-06-01

    Geologic ultrafiltration—slowing of solutes with respect to flowing groundwater—poses a conundrum: it is consistently observed experimentally in clay-rich lithologies, but has been difficult to identify in subsurface data. Resolving this could be important for clarifying clay and shale transport properties at large scales as well as interpreting solute and isotope patterns for applications ranging from nuclear waste repository siting to understanding fluid transport in tectonically active environments. Simulations of one-dimensional NaCl transport across ultrafiltering clay membrane strata constrained by emerging data on geologic membrane properties showed different ultrafiltration effects than have often been envisioned. In relatively high-permeability advection-dominated regimes, salinity increases occurred mostly within membrane units while their effluent salinity initially fell and then rose to match solute delivery. In relatively low-permeability diffusion-dominated regimes, salinity peaked at the membrane upstream boundary and effluent salinity remained low. In both scenarios, however, only modest salinity changes (up to ˜3 g L-1) occurred because of self-limiting tendencies; membrane efficiency declines as salinity rises, and although sediment compaction increases efficiency, it is also decreases permeability and allows diffusive transport to dominate. It appears difficult for ultrafiltration to generate brines as speculated, but widespread and less extreme ultrafiltration effects in the subsurface could be unrecognized. Conditions needed for ultrafiltration are present in settings that include topographically-driven flow systems, confined aquifer systems subjected to injection or withdrawal, compacting basins, and accretionary complexes.

  3. Simulating groundwater-peatland interactions in depression and slope peatlands in southern Quebec (Canada)

    Science.gov (United States)

    Larocque, M.; Quillet, A.; Paniconi, C.

    2013-12-01

    It is crucial to understand hydrogeological interactions between aquifers and peatlands in order to grasp the influence of aquifers in peatland water budgets, to understand the role of groundwater in the evolution or organic matter deposition, and to quantify how a peatland can sustain groundwater levels in a superficial aquifer. These questions have rarely been addressed in literature and there is currently no understanding of which process dominates aquifer-peatland exchanges in different geomorphological settings. The main purpose of the study was to use groundwater flow modeling to answer these questions in two contrasted geological contexts of southern Quebec (Canada). During a three-year study, six peatlands have been instrumented in the Becancour (Centre-du-Quebec) and Amos (Abitibi-Temiscamingue) regions of southern Quebec (Canada). At each site, either one or two transects of six piezometer nests (at 1.20 m depth in the organic deposits and in the mineral deposits below the peat) have been installed, for a total of twelve aquifer-peatland transects of approximately 500 m. The stratigraphy and geometry of the peatland-aquifer system, as well as the hydrodynamic properties of the organic and mineral deposits have been measured at all sites. Groundwater levels have been recorded from autumn 2010 to summer 2012. The Becancour peatlands have developed in depressions while the Amos peatlands have developed through the paludification of esker slopes. The maximum peat thickness measured in the Bécancour peatlands is 6.4 m while it is 4.5 m in the Amos region. In both regions, peatlands are fringed by sandy deposits that extend at least partly under the organic deposits. The thickness of these underlying deposits is not well defined, but available data suggests a metric scale thickness in areas close to the adjacent superficial aquifer. Field data is used to create 2D numerical models in Modflow to simulate flow between the shallow groundwater and the peatland on

  4. SLiM : an improved soil moisture balance method to simulate runoff and potential groundwater recharge processes using spatio-temporal weather and catchment characteristics

    OpenAIRE

    Wang, Lei; Barkwith, Andrew; Jackson, Christopher; Ellis, Michael

    2012-01-01

    The numerical modelling of runoff and groundwater recharge plays an important role in water resource management. The methodologies developed for these simulations should represent the key physical processes, and be applicable in a wide variety of climates for routine simulations using readily available field information. This paper describes the development of a Soil and Landuse based rainfall-runoff and recharge Model (SLiM) based on Rushton’s method – a single soil layer groundwater recharg...

  5. Molecular electronics: insight from first-principles transport simulations.

    Science.gov (United States)

    Paulsson, Magnus; Frederiksen, Thomas; Brandbyge, Mads

    2010-01-01

    Conduction properties of nanoscale contacts can be studied using first-principles simulations. Such calculations give insight into details behind the conductance that is not readily available in experiments. For example, we may learn how the bonding conditions of a molecule to the electrodes affect the electronic transport. Here we describe key computational ingredients and discuss these in relation to simulations for scanning tunneling microscopy (STM) experiments with C60 molecules where the experimental geometry is well characterized. We then show how molecular dynamics simulations may be combined with transport calculations to study more irregular situations, such as the evolution of a nanoscale contact with the mechanically controllable break-junction technique. Finally we discuss calculations of inelastic electron tunnelling spectroscopy as a characterization technique that reveals information about the atomic arrangement and transport channels.

  6. An Integrated Simulation, Inference and Optimization Approach for Groundwater Remediation with Two-stage Health-Risk Assessment

    Directory of Open Access Journals (Sweden)

    Aili Yang

    2018-05-01

    Full Text Available In this study, an integrated simulation, inference and optimization approach with two-stage health risk assessment (i.e., ISIO-THRA is developed for supporting groundwater remediation for a petroleum-contaminated site in western Canada. Both environmental standards and health risk are considered as the constraints in the ISIO-THRA model. The health risk includes two parts: (1 the health risk during the remediation process and (2 the health risk in the natural attenuation period after remediation. In the ISIO-THRA framework, the relationship between contaminant concentrations and time is expressed through first-order decay models. The results demonstrate that: (1 stricter environmental standards and health risk would require larger pumping rates for the same remediation duration; (2 higher health risk may happen in the period of the remediation process; (3 for the same environmental standard and acceptable health-risk level, the remediation techniques that take the shortest time would be chosen. ISIO-THRA can help to systematically analyze interaction among contaminant transport, remediation duration, and environmental and health concerns, and further provide useful supportive information for decision makers.

  7. Identifying functional zones of denitrification in heterogeneous aquifer systems by numerical simulations - a case study

    Science.gov (United States)

    Jang, E.; Kalbacher, T.; He, W.; Shao, H.; Schueth, C.; Kolditz, O.

    2014-12-01

    Nitrate contamination in shallow groundwater is still one of the common problems in many countries. Because of its high solubility and anionic nature, nitrate can easily leach through soil and persist in groundwater for decades. High nitrate concentration has been suggested as a major cause of accelerated eutrophication, methemoglobinemia and gastric cancer. There are several factors influencing the fate of nitrate in groundwater system, which is e.g. distribution of N- sources to soil and groundwater, distribution and amount of reactive substances maintaining denitrification, rate of nitrate degradation and its kinetics, and geological characteristics of the aquifer. Nitrate transport and redox transformation processes are closely linked to complex and spatially distributed physical and chemical interaction, therefore it is difficult to predict and quantify in the field and laboratory experiment. Models can play a key role in elucidation of nitrate reduction pathway in groundwater system and in the design and evaluation of field tests to investigate in situ remediation technologies as well. The goal of the current study is to predict groundwater vulnerability to nitrate, to identify functional zones of denitrification in heterogeneous aquifer systems and to describe the uncertainty of the predictions due to scale effects. For this aim, we developed a kinetic model using multi-component mass transport code OpenGeoSys coupling with IPhreeqc module of the geochemical solver PHREEQC. The developed model included sequential aerobic and nitrate-based respiration, multi-Monod kinetics, multi-species biogeochemical reactions, and geological characteristics of the groundwater aquifer. Moreover water-rock interaction such as secondary mineral precipitation was also included in this model. In this presentation, we focused on the general modelling approach and present the simulation results of nitrate transport simulation in a hypothetical aquifer systems based on data from

  8. Coupled hydrogeological and reactive transport modelling of the Simpevarp area (Sweden)

    International Nuclear Information System (INIS)

    Molinero, Jorge; Raposo, Juan R.; Galindez, Juan M.; Arcos, David; Guimera, Jordi

    2008-01-01

    The Simpevarp area is one of the alternative sites being considered for the deep geological disposal of high level radioactive waste in Sweden. In this paper, a coupled regional groundwater flow and reactive solute transport model of the Simpevarp area is presented that integrates current hydrogeological and hydrochemical data of the area. The model simulates the current hydrochemical pattern of the groundwater system in the area. To that aim, a conceptual hydrochemical model was developed in order to represent the dominant chemical processes. Groundwater flow conditions were reproduced by taking into account fluid-density-dependent groundwater flow and regional hydrogeologic boundary conditions. Reactive solute transport calculations were performed on the basis of the velocity field so obtained. The model was calibrated and sensitivity analyses were carried out in order to investigate the effects of heterogeneities of hydraulic conductivity in the subsurface medium. Results provided by the reactive transport model are in good agreement with much of the measured hydrochemical data. This paper emphasizes the appropriateness of the use of reactive solute transport models when water-rock interaction reactions are involved, and demonstrates what powerful tools they are for the interpretation of hydrogeological and hydrochemical data from site geological repository characterization programs, by providing a qualitative framework for data analysis and testing of conceptual assumptions in a process-oriented approach

  9. Simulation-Optimization Model for Seawater Intrusion Management at Pingtung Coastal Area, Taiwan

    Science.gov (United States)

    Huang, P. S.; Chiu, Y.

    2015-12-01

    In 1970's, the agriculture and aquaculture were rapidly developed at Pingtung coastal area in southern Taiwan. The groundwater aquifers were over-pumped and caused the seawater intrusion. In order to remedy the contaminated groundwater and find the best strategies of groundwater usage, a management model to search the optimal groundwater operational strategies is developed in this study. The objective function is to minimize the total amount of injection water and a set of constraints are applied to ensure the groundwater levels and concentrations are satisfied. A three-dimension density-dependent flow and transport simulation model, called SEAWAT developed by U.S. Geological Survey, is selected to simulate the phenomenon of seawater intrusion. The simulation model is well calibrated by the field measurements and replaced by the surrogate model of trained artificial neural networks (ANNs) to reduce the computational time. The ANNs are embedded in the management model to link the simulation and optimization models, and the global optimizer of differential evolution (DE) is applied for solving the management model. The optimal results show that the fully trained ANNs could substitute the original simulation model and reduce much computational time. Under appropriate setting of objective function and constraints, DE can find the optimal injection rates at predefined barriers. The concentrations at the target locations could decrease more than 50 percent within the planning horizon of 20 years. Keywords : Seawater intrusion, groundwater management, numerical model, artificial neural networks, differential evolution

  10. Development of a model to simulate groundwater inundation induced by sea-level rise and high tides in Honolulu, Hawaii.

    Science.gov (United States)

    Habel, Shellie; Fletcher, Charles H; Rotzoll, Kolja; El-Kadi, Aly I

    2017-05-01

    Many of the world's largest cities face risk of sea-level rise (SLR) induced flooding owing to their limited elevations and proximities to the coastline. Within this century, global mean sea level is expected to reach magnitudes that will exceed the ground elevation of some built infrastructure. The concurrent rise of coastal groundwater will produce additional sources of inundation resulting from narrowing and loss of the vertical unsaturated subsurface space. This has implications for the dense network of buried and low-lying infrastructure that exists across urban coastal zones. Here, we describe a modeling approach that simulates narrowing of the unsaturated space and groundwater inundation (GWI) generated by SLR-induced lifting of coastal groundwater. The methodology combines terrain modeling, groundwater monitoring, estimation of tidal influence, and numerical groundwater-flow modeling to simulate future flood scenarios considering user-specified tide stages and magnitudes of SLR. We illustrate the value of the methodology by applying it to the heavily urbanized and low-lying Waikiki area of Honolulu, Hawaii. Results indicate that SLR of nearly 1 m generates GWI across 23% of the 13 km 2 study area, threatening $5 billion of taxable real estate and 48 km of roadway. Analysis of current conditions reveals that 86% of 259 active cesspool sites in the study area are likely inundated. This suggests that cesspool effluent is currently entering coastal groundwater, which not only leads to degradation of coastal environments, but also presents a future threat to public health as GWI would introduce effluent at the ground surface. Copyright © 2017 Elsevier Ltd. All rights reserved.

  11. Experimental and numerical modelling of surface water-groundwater flow and pollution interactions under tidal forcing

    Science.gov (United States)

    Spanoudaki, Katerina; Bockelmann-Evans, Bettina; Schaefer, Florian; Kampanis, Nikolaos; Nanou-Giannarou, Aikaterini; Stamou, Anastasios; Falconer, Roger

    2015-04-01

    continuous tide on the coastal side. The integrated surface water-groundwater numerical model IRENE (Spanoudaki et al., 2009, Spanoudaki, 2010) was also used in the study, with the numerical model predictions being compared with experimental results, which provide a valuable database for model calibration and validation. IRENE couples the 3D, non-steady state Navier-Stokes equations, after Reynolds averaging and with the assumption of hydrostatic pressure distribution, to the equations describing 3D saturated groundwater flow of constant density. The model uses the finite volume method with a cell-centered structured grid providing thus flexibility and accuracy in simulating irregular boundary geometries. A semi-implicit finite difference scheme is used to solve the surface water flow equations, while a fully implicit finite difference scheme is used for the groundwater equations. Pollution interactions are simulated by coupling the advection-diffusion equation describing the fate and transport of contaminants introduced in a 3D turbulent flow field to the partial differential equation describing the fate and transport of contaminants in 3D transient groundwater flow systems. References Ebrahimi, K., Falconer, R.A. and Lin B. (2007). Flow and solute fluxes in integrated wetland and coastal systems. Environmental Modelling and Software, 22 (9), 1337-1348. Hughes, S.A. (1995). Physical Modelling and Laboratory Techniques in Coastal Engineering. World Scientific Publishing Co. Pte. Ltd., Singapore. Kuan, W.K., Jin, G., Xin, P., Robinson, C. Gibbes, B. and Li. L. (2012). Tidal influence on seawater intrusion in unconfined coastal aquifers. Water Resources Research, 48 (2), doi:10.1029/2011WR010678. Spanoudaki, K., Stamou, A.I. and Nanou-Giannarou, A. (2009). Development and verification of a 3-D integrated surface water-groundwater model. Journal of Hydrology, 375 (3-4), 410-427. Spanoudaki, K. (2010). Integrated numerical modelling of surface water groundwater systems (in Greek

  12. Approaches to groundwater travel time

    International Nuclear Information System (INIS)

    Kaplan, P.; Klavetter, E.; Peters, R.

    1989-01-01

    One of the objectives of performance assessment for the Yucca Mountain Project is to estimate the groundwater travel time at Yucca Mountain, Nevada, to determine whether the site complies with the criteria specified in the Code of Federal Regulations. The numerical standard for performance in these criteria is based on the groundwater travel time along the fastest path of likely radionuclide transport from the disturbed zone to the accessible environment. The concept of groundwater travel time, as proposed in the regulations, does not have a unique mathematical statement. The purpose of this paper is to discuss (1) the ambiguities associated with the regulatory specification of groundwater travel time, (2) two different interpretations of groundwater travel time, and (3) the effect of the two interpretations on estimates of the groundwater travel time. 3 refs., 2 figs., 2 tabs

  13. On mobilization of lead and arsenic in groundwater in response to CO2 leakage from deep geological storage

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, L.; Apps, J.A.; Zhang, Y.; Xu, T.; Birkholzer, J.T.

    2009-07-01

    If carbon dioxide stored in deep saline aquifers were to leak into an overlying aquifer containing potable groundwater, the intruding CO{sub 2} would change the geochemical conditions and cause secondary effects mainly induced by changes in pH In particular, hazardous trace elements such as lead and arsenic, which are present in the aquifer host rock, could be mobilized. In an effort to evaluate the potential risks to potable water quality, reactive transport simulations were conducted to evaluate to what extent and mechanisms through which lead and arsenic might be mobilized by intrusion of CO{sub 2}. An earlier geochemical evaluation of more than 38,000 groundwater quality analyses from aquifers throughout the United States and an associated literature review provided the basis for setting up a reactive transport model and examining its sensitivity to model variation. The evaluation included identification of potential mineral hosts containing hazardous trace elements, characterization of the modal bulk mineralogy for an arenaceous aquifer, and augmentation of the required thermodynamic data. The reactive transport simulations suggest that CO{sub 2} ingress into a shallow aquifer can mobilize significant lead and arsenic, contaminating the groundwater near the location of intrusion and further downstream. Although substantial increases in aqueous concentrations are predicted compared to the background values, the maximum permitted concentration for arsenic in drinking water was exceeded in only a few cases, whereas that for lead was never exceeded.

  14. Integrated modeling of groundwater-surface water interactions in a tile-drained agricultural field: The importance of directly measured flow route contributions

    NARCIS (Netherlands)

    Rozemeijer, J.C.; Velde, Y. van der; McLaren, R.G.; Geer, F.C. van; Broers, H.P.; Bierkens, M.F.P.

    2010-01-01

    Understanding the dynamics of groundwater-surface water interaction is needed to evaluate and simulate water and solute transport in catchments. However, direct measurements of the contributions of different flow routes from specific surfaces within a catchment toward the surface water are rarely

  15. Groundwater flow modelling of periods with periglacial and glacial climate conditions - Laxemar

    Energy Technology Data Exchange (ETDEWEB)

    Vidstrand, Patrik (TerraSolve AB, Floda (Sweden)); Rhen, Ingvar (SWECO Environment AB, Falun (Sweden)); Zugec, Nada (Bergab, Goeteborg (Sweden))

    2010-12-15

    As a part of the license application for a final repository for spent nuclear fuel at Forsmark, the Swedish Nuclear Fuel and Waste Management Company (SKB) has undertaken a series of groundwater flow modelling studies. These represent time periods with different hydraulic conditions and the simulations carried out contribute to the overall evaluation of the repository design and long-term radiological safety. This report is concerned with the modelling of a repository at the Laxemar-Simpevarp site during periglacial and glacial climate conditions as a comparison to corresponding modelling carried out for Forsmark /Vidstrand et al. 2010/. The groundwater flow modelling study reported here comprises a coupled thermal-hydraulic-chemical (T-H-C) analysis of periods with periglacial and glacial climate conditions. The objective of the report is to provide bounding hydrogeological estimates at different stages during glaciation and deglaciation of a glacial cycle at Laxemar. Three cases with different climate conditions are analysed here: (i) Temperate case, (ii) Glacial case without permafrost, and (iii) Glacial case with permafrost. The glacial periods are transient and encompass approximately 13,000 years. The simulation results comprise pressures, Darcy fluxes, and water salinities, as well as advective transport performance measures obtained by particle tracking such as flow path lengths, travel times and flow-related transport resistances. The modelling is accompanied by a sensitivity study that addresses the impact of the following matters: the direction of the ice sheet advance and the bedrock hydraulic and transport properties

  16. Coupling a three-dimensional subsurface flow and transport model with a land surface model to simulate stream–aquifer–land interactions (CP v1.0

    Directory of Open Access Journals (Sweden)

    G. Bisht

    2017-12-01

    Full Text Available A fully coupled three-dimensional surface and subsurface land model is developed and applied to a site along the Columbia River to simulate three-way interactions among river water, groundwater, and land surface processes. The model features the coupling of the Community Land Model version 4.5 (CLM4.5 and a massively parallel multiphysics reactive transport model (PFLOTRAN. The coupled model, named CP v1.0, is applied to a 400 m × 400 m study domain instrumented with groundwater monitoring wells along the Columbia River shoreline. CP v1.0 simulations are performed at three spatial resolutions (i.e., 2, 10, and 20 m over a 5-year period to evaluate the impact of hydroclimatic conditions and spatial resolution on simulated variables. Results show that the coupled model is capable of simulating groundwater–river-water interactions driven by river stage variability along managed river reaches, which are of global significance as a result of over 30 000 dams constructed worldwide during the past half-century. Our numerical experiments suggest that the land-surface energy partitioning is strongly modulated by groundwater–river-water interactions through expanding the periodically inundated fraction of the riparian zone, and enhancing moisture availability in the vadose zone via capillary rise in response to the river stage change. Meanwhile, CLM4.5 fails to capture the key hydrologic process (i.e., groundwater–river-water exchange at the site, and consequently simulates drastically different water and energy budgets. Furthermore, spatial resolution is found to significantly impact the accuracy of estimated the mass exchange rates at the boundaries of the aquifer, and it becomes critical when surface and subsurface become more tightly coupled with groundwater table within 6 to 7 meters below the surface. Inclusion of lateral subsurface flow influenced both the surface energy budget and subsurface transport processes as a result

  17. Simulation of the effects of rainfall and groundwater use on historical lake water levels, groundwater levels, and spring flows in central Florida

    Science.gov (United States)

    O'Reilly, Andrew M.; Roehl, Edwin A.; Conrads, Paul; Daamen, Ruby C.; Petkewich, Matthew D.

    2014-01-01

    The urbanization of central Florida has progressed substantially in recent decades, and the total population in Lake, Orange, Osceola, Polk, and Seminole Counties more than quadrupled from 1960 to 2010. The Floridan aquifer system is the primary source of water for potable, industrial, and agricultural purposes in central Florida. Despite increases in groundwater withdrawals to meet the demand of population growth, recharge derived by infiltration of rainfall in the well-drained karst terrain of central Florida is the largest component of the long-term water balance of the Floridan aquifer system. To complement existing physics-based groundwater flow models, artificial neural networks and other data-mining techniques were used to simulate historical lake water level, groundwater level, and spring flow at sites throughout the area. Historical data were examined using descriptive statistics, cluster analysis, and other exploratory analysis techniques to assess their suitability for more intensive data-mining analysis. Linear trend analyses of meteorological data collected by the National Oceanic and Atmospheric Administration at 21 sites indicate 67 percent of sites exhibited upward trends in air temperature over at least a 45-year period of record, whereas 76 percent exhibited downward trends in rainfall over at least a 95-year period of record. Likewise, linear trend analyses of hydrologic response data, which have varied periods of record ranging in length from 10 to 79 years, indicate that water levels in lakes (307 sites) were about evenly split between upward and downward trends, whereas water levels in 69 percent of wells (out of 455 sites) and flows in 68 percent of springs (out of 19 sites) exhibited downward trends. Total groundwater use in the study area increased from about 250 million gallons per day (Mgal/d) in 1958 to about 590 Mgal/d in 1980 and remained relatively stable from 1981 to 2008, with a minimum of 559 Mgal/d in 1994 and a maximum of 773

  18. Plasma confinement theory and transport simulation

    International Nuclear Information System (INIS)

    Ross, D.W.

    1989-06-01

    An overview of the program has been given in the contract proposal. The principal objectives are: to provide theoretical interpretation and computer modelling for the TEXT tokamak, and to advance the simulation studies of tokamaks generally, functioning as a National Transport Center. We also carry out equilibrium and stability studies in support of the TEXT upgrade, and work has continued on Alfven waves and MFENET software development. The focus of the program is to lay the groundwork for detailed comparison with experiment of the various transport theories to improve physics understanding and confidence in predictions of future machine behavior. This involves: to collect, in retrievable form, the data from TEXT and other tokamaks; to make the data available through easy-to-use interfaces; to develop criteria for success in fitting models to the data; to maintain the Texas transport code CHAPO and make it available to users; to collect theoretical models and implement them in the transport code; and to carry out simulation studies and evaluate fits to the data. In the following we outline the progress made in fiscal year 1989. Of special note are the proposed participation of our data base project in the ITER program, and a proposed q-profile diagnostic based on our neutral transport studies. We have emphasized collaboration with the TEXT experimentalists, making as much use as possible of the measured fluctuation spectra. 52 refs

  19. Groundwater Flow Computed with Modflow and Isotopic Age Tracer Data in the Continental Intercalaire (Sahara)

    Energy Technology Data Exchange (ETDEWEB)

    Petersen, J. O.; Goncalves, J.; Deschamps, P.; Hamelin, B. [Centre Europeen de Recherche et d' Enseignement de Geosciences de l' Environnement, Aix-en-Provence (France); Zouari, K. [Laboratoire de Radio-Analyses et Environnement, Sfax (Tunisia); Guendouz, A. [University of Blida, Science Engineering Faculty, Soummaa Blida (Algeria); Michelot, J. -L. [Interactions et Dynamique des Environnements de Surface, Universite Paris-Sud, Orsay (France)

    2013-07-15

    In one of the largest confined aquifers of the world, the Continental Intercalaire (Sahara), which is located in an arid region (57 mm/y of mean of precipitation), groundwater flow patterns are rather complex. Coupling measurements of isotopic composition of water and age mass calculations obtained by numerical simulations can allow, to a greater extent than a simple comparison, to constrain and validate the recharge scenario, transport and age of groundwater. First, the multiple tracers {sup 14}C, {sup 36}Cl, or {sup 234}U/{sup 238}U used in this study including noble gases such as {sup 4}He, allow investigation of a large range of groundwater ages. Then a MODFLOW simulation is built using (i) the distribution of hydrological parameters, (ii) geometrical limits and iii) the concept of age mass of water, accounting for the tracers data. This approach improves the understanding of the hydrodynamics of this system. In particular, the mixing of old and young waters should be better constrained and the interpretation of paleohydrological conditions is permitted. (author)

  20. Guidelines for selecting codes for ground-water transport modeling of low-level waste burial sites. Volume 2. Special test cases

    International Nuclear Information System (INIS)

    Simmons, C.S.; Cole, C.R.

    1985-08-01

    This document was written for the National Low-Level Waste Management Program to provide guidance for managers and site operators who need to select ground-water transport codes for assessing shallow-land burial site performance. The guidance given in this report also serves the needs of applications-oriented users who work under the direction of a manager or site operator. The guidelines are published in two volumes designed to support the needs of users having different technical backgrounds. An executive summary, published separately, gives managers and site operators an overview of the main guideline report. Volume 1, titled ''Guideline Approach,'' consists of Chapters 1 through 5 and a glossary. Chapters 2 through 5 provide the more detailed discussions about the code selection approach. This volume, Volume 2, consists of four appendices reporting on the technical evaluation test cases designed to help verify the accuracy of ground-water transport codes. 20 refs

  1. The Application of Neutron Transport Green's Functions to Threat Scenario Simulation

    Science.gov (United States)

    Thoreson, Gregory G.; Schneider, Erich A.; Armstrong, Hirotatsu; van der Hoeven, Christopher A.

    2015-02-01

    Radiation detectors provide deterrence and defense against nuclear smuggling attempts by scanning vehicles, ships, and pedestrians for radioactive material. Understanding detector performance is crucial to developing novel technologies, architectures, and alarm algorithms. Detection can be modeled through radiation transport simulations; however, modeling a spanning set of threat scenarios over the full transport phase-space is computationally challenging. Previous research has demonstrated Green's functions can simulate photon detector signals by decomposing the scenario space into independently simulated submodels. This paper presents decomposition methods for neutron and time-dependent transport. As a result, neutron detector signals produced from full forward transport simulations can be efficiently reconstructed by sequential application of submodel response functions.

  2. Simulating the Interactions Among Land Use, Transportation ...

    Science.gov (United States)

    In most transportation studies, computer models that forecast travel behavior statistics for a future year use static projections of the spatial distribution of future population and employment growth as inputs. As a result, they are unable to account for the temporally dynamic and non-linear interactions among transportation, land use, and socioeconomic systems. System dynamics (SD) provides a common framework for modeling the complex interactions among transportation and other related systems. This study uses a SD model to simulate the cascading impacts of a proposed light rail transit (LRT) system in central North Carolina, USA. The Durham-Orange Light Rail Project (D-O LRP) SD model incorporates relationships among the land use, transportation, and economy sectors to simulate the complex feedbacks that give rise to the travel behavior changes forecasted by the region’s transportation model. This paper demonstrates the sensitivity of changes in travel behavior to the proposed LRT system and the assumptions that went into the transportation modeling, and compares those results to the impacts of an alternative fare-free transit system. SD models such as the D-O LRP SD model can complement transportation studies by providing valuable insight into the interdependent community systems that collectively contribute to travel behavior changes. Presented at the 35th International Conference of the System Dynamics Society in Cambridge, MA, July 18th, 2017

  3. A groundwater mass flux model for screening the groundwater-to-indoor-air exposure pathway

    Energy Technology Data Exchange (ETDEWEB)

    McHugh, T.; Blanc, P.C. de; Connor, J. [Groundwater Services Inc, Houston, TX (United States)

    2003-07-01

    The potential for human exposure via volatilisation of groundwater contaminants into indoor air has been a focus of increasing concern in recent years. At a small number of sites, elevated indoor vapour concentrations have been measured within buildings overlying shallow groundwater contaminated with chlorinated solvents, causing public concern over the potential for similar problems at other corrective action sites. In addition, use of the screening-levelmodel developed by Johnson and Ettinger (1991) for the groundwater-to-indoor-air exposure pathway has suggested that low microgram per litre (ug/L)-range concentrations of either chlorinated or non-chlorinated volatile organic compounds dissolved in groundwater could result in indoor vapour concentrations in excess of applicable risk-based exposure limits. As an alternative screening tool, this paper presents a groundwater mass flux model for evaluation of transport to indoor air. The mass flux model is intended to serve as a highly conservative screening tool that over-predicts groundwater-to-indoor-air mass flux, yet still provides sufficient sensitivity to identify sites for which the groundwater-to-indoor air exposure pathway is not a concern. (orig.)

  4. Implementation of Solute Transport in the Vadose Zone into the `HYDRUS Package for MODFLOW'

    Science.gov (United States)

    Simunek, J.; Beegum, S.; Szymkiewicz, A.; Sudheer, K. P.

    2017-12-01

    The 'HYDRUS package for MODFLOW' was developed by Seo et al. (2007) and Twarakavi et al. (2008) to simultaneously evaluate transient water flow in both unsaturated and saturated zones. The package, which is based on the HYDRUS-1D model (Šimůnek et al., 2016) simulating unsaturated water flow in the vadose zone, was incorporated into MODFLOW (Harbaugh et al., 2000) simulating saturated groundwater flow. The HYDRUS package in the coupled model can be used to represent the effects of various unsaturated zone processes, including infiltration, evaporation, root water uptake, capillary rise, and recharge in homogeneous or layered soil profiles. The coupled model is effective in addressing spatially-variable saturated-unsaturated hydrological processes at the regional scale, allowing for complex layering in the unsaturated zone, spatially and temporarily variable water fluxes at the soil surface and in the root zone, and with alternating recharge and discharge fluxes (Twarakavi et al., 2008). One of the major limitations of the coupled model was that it could not be used to simulate at the same time solute transport. However, solute transport is highly dependent on water table fluctuations due to temporal and spatial variations in groundwater recharge. This is an important concern when the coupled model is used for analyzing groundwater contamination due to transport through the unsaturated zone. The objective of this study is to integrate the solute transport model (the solute transport part of HYDRUS-1D for the unsaturated zone and MT3DMS (Zheng and Wang, 1999; Zheng, 2009) for the saturated zone) into an existing coupled water flow model. The unsaturated zone component of the coupled model can consider solute transport involving many biogeochemical processes and reactions, including first-order degradation, volatilization, linear or nonlinear sorption, one-site kinetic sorption, two-site sorption, and two-kinetic sites sorption (Šimůnek and van Genuchten, 2008

  5. Probabilistic, sediment-geochemical parameterisation of the groundwater compartment of the Netherlands for spatially distributed, reactive transport modelling

    Science.gov (United States)

    Janssen, Gijs; Gunnink, Jan; van Vliet, Marielle; Goldberg, Tanya; Griffioen, Jasper

    2017-04-01

    Pollution of groundwater aquifers with contaminants as nitrate is a common problem. Reactive transport models are useful to predict the fate of such contaminants and to characterise the efficiency of mitigating or preventive measures. Parameterisation of a groundwater transport model on reaction capacity is a necessary step during building the model. Two Dutch, national programs are combined to establish a methodology for building a probabilistic model on reaction capacity of the groundwater compartment at the national scale: the Geological Survey program and the NHI Netherlands Hydrological Instrument program. Reaction capacity is considered as a series of geochemical characteristics that control acid/base condition, redox condition and sorption capacity. Five primary reaction capacity variables are characterised: 1. pyrite, 2. non-pyrite, reactive iron (oxides, siderite and glauconite), 3. clay fraction, 4. organic matter and 5. Ca-carbonate. Important reaction capacity variables that are determined by more than one solid compound are also deduced: 1. potential reduction capacity (PRC) by pyrite and organic matter, 2. cation-exchange capacity (CEC) by organic matter and clay content, 3. carbonate buffering upon pyrite oxidation (CPBO) by carbonate and pyrite. Statistical properties of these variables are established based on c. 16,000 sediment geochemical analyses. The first tens of meters are characterised based on 25 regions using combinations of lithological class and geological formation as strata. Because of both less data and more geochemical uniformity, the deeper subsurface is characterised in a similar way based on 3 regions. The statistical data is used as input in an algoritm that probabilistically calculates the reaction capacity per grid cell. First, the cumulative frequency distribution (cfd) functions are calculated from the statistical data for the geochemical strata. Second, all voxel cells are classified into the geochemical strata. Third, the

  6. SITHA program for simulating hadron transport in the 100-1010eV energy range. Simulation of neutron transport with E6 eV

    International Nuclear Information System (INIS)

    Daniehl', A.V.; Dushin, V.N.

    1987-01-01

    The methods for simulation of neutron transport with Z<20 MeV used in the SITHA (simulation transport hadron) program, the original library of group microconstants (175 groups) with subgroup description of resonance range and a set of programs for its creation are described. The results of a number of integral experiments are discussed

  7. Modeling Np and Pu transport with a surface complexation model and spatially variant sorption capacities: Implications for reactive transport modeling and performance assessments of nuclear waste disposal sites

    Science.gov (United States)

    Glynn, P.D.

    2003-01-01

    One-dimensional (1D) geochemical transport modeling is used to demonstrate the effects of speciation and sorption reactions on the ground-water transport of Np and Pu, two redox-sensitive elements. Earlier 1D simulations (Reardon, 1981) considered the kinetically limited dissolution of calcite and its effect on ion-exchange reactions (involving 90Sr, Ca, Na, Mg and K), and documented the spatial variation of a 90Sr partition coefficient under both transient and steady-state chemical conditions. In contrast, the simulations presented here assume local equilibrium for all reactions, and consider sorption on constant potential, rather than constant charge, surfaces. Reardon's (1981) seminal findings on the spatial and temporal variability of partitioning (of 90Sr) are reexamined and found partially caused by his assumption of a kinetically limited reaction. In the present work, sorption is assumed the predominant retardation process controlling Pu and Np transport, and is simulated using a diffuse-double-layer-surface-complexation (DDLSC) model. Transport simulations consider the infiltration of Np- and Pu-contaminated waters into an initially uncontaminated environment, followed by the cleanup of the resultant contamination with uncontaminated water. Simulations are conducted using different spatial distributions of sorption capacities (with the same total potential sorption capacity, but with different variances and spatial correlation structures). Results obtained differ markedly from those that would be obtained in transport simulations using constant Kd, Langmuir or Freundlich sorption models. When possible, simulation results (breakthrough curves) are fitted to a constant K d advection-dispersion transport model and compared. Functional differences often are great enough that they prevent a meaningful fit of the simulation results with a constant K d (or even a Langmuir or Freundlich) model, even in the case of Np, a weakly sorbed radionuclide under the

  8. The transport of antibiotic resistance genes and residues in groundwater near swine production facilities

    Science.gov (United States)

    Lin, Y. F.; Yannarell, A. C.; Mackie, R. I.; Krapac, I. G.; Chee-Sanford, J. S.; Koike, S.

    2008-12-01

    The use of antibiotics at concentrated animal feeding operations (CAFOs) for disease prevention, disease treatment, and growth promotion can contribute to the spread of antibiotic compounds, their breakdown products, and antibiotic resistant bacteria and/or the genes that confer resistance. In addition, constitutive use of antibiotics at sub-therapeutic levels can select for antibiotic resistance among the bacteria that inhabit animal intestinal tracts, onsite manure treatment facilities, and any environments receiving significant inputs of manure (e.g. through waste lagoon leakage or fertilizer amendments to farm soils). If the antibiotic resistant organisms persist in these new environments, or if they participate in genetic exchanges with the native microflora, then CAFOs may constitute a significant reservoir for the spread of antibiotic resistance to the environment at large. Our results have demonstrated that leakage from waste treatment lagoons can influence the presence and persistence of tetracycline resistance genes in the shallow aquifer adjacent to swine CAFOs, and molecular phylogeny allowed us to distinguish "native" tetracycline resistance genes in control groundwater wells from manure-associated genes introduced from the lagoon. We have also been able to detect the presence of erythromycin resistance genes in CAFO surface and groundwater even though erythromycin is strictly reserved for use in humans and thus is not utilized at any of these sites. Ongoing research, including modeling of particle transport in groundwater, will help to determine the potential spatial and temporal extent of CAFO-derived antibiotic resistance.

  9. Simulant composition for the Mixed Waste Management Facility (MWMF) groundwater remediation project

    International Nuclear Information System (INIS)

    Siler, J.L.

    1992-01-01

    A project has been initiated at the request of ER to study and remediate the groundwater contamination at the Mixed Waste Management Facility (MWMF). This water contains a wide variety of both inorganics (e.g., sodium) and organics (e.g., benzene, trichloroethylene). Most compounds are present in the ppB range, and certain components (e.g., trichloroethylene, silver) are present at concentrations that exceed the primary drinking water standards (PDWS). These compounds must be reduced to acceptable levels as per RCRA and CERCLA orders. This report gives a listing of the important constituents which are to be included in a simulant to model the MWMF aquifer. This simulant will be used to evaluate the feasibility of various state of the art separation/destruction processes for remediating the aquifer

  10. Integrated heat transport simulation of high ion temperature plasma of LHD

    International Nuclear Information System (INIS)

    Murakami, S.; Yamaguchi, H.; Sakai, A.

    2014-10-01

    A first dynamical simulation of high ion temperature plasma with carbon pellet injection of LHD is performed by the integrated simulation GNET-TD + TASK3D. NBI heating deposition of time evolving plasma is evaluated by the 5D drift kinetic equation solver, GNET-TD and the heat transport of multi-ion species plasma (e, H, He, C) is studied by the integrated transport simulation code, TASK3D. Achievement of high ion temperature plasma is attributed to the 1) increase of heating power per ion due to the temporal increase of effective charge, 2) reduction of effective neoclassical transport with impurities, 3) reduction of turbulence transport. The reduction of turbulence transport is most significant contribution to achieve the high ion temperature and the reduction of the turbulent transport from the L-mode plasma (normal hydrogen plasma) is evaluated to be a factor about five by using integrated heat transport simulation code. Applying the Z effective dependent turbulent reduction model we obtain a similar time behavior of ion temperature after the C pellet injection with the experimental results. (author)

  11. Improvement of the physically-based groundwater model simulations through complementary correction of its errors

    Directory of Open Access Journals (Sweden)

    Jorge Mauricio Reyes Alcalde

    2017-04-01

    Full Text Available Physically-Based groundwater Models (PBM, such MODFLOW, are used as groundwater resources evaluation tools supposing that the produced differences (residuals or errors are white noise. However, in the facts these numerical simulations usually show not only random errors but also systematic errors. For this work it has been developed a numerical procedure to deal with PBM systematic errors, studying its structure in order to model its behavior and correct the results by external and complementary means, trough a framework called Complementary Correction Model (CCM. The application of CCM to PBM shows a decrease in local biases, better distribution of errors and reductions in its temporal and spatial correlations, with 73% of reduction in global RMSN over an original PBM. This methodology seems an interesting chance to update a PBM avoiding the work and costs of interfere its internal structure.

  12. ANALYTICAL AND SIMULATION PLANNING MODEL OF URBAN PASSENGER TRANSPORT

    Directory of Open Access Journals (Sweden)

    Andrey Borisovich Nikolaev

    2017-09-01

    Full Text Available The article described the structure of the analytical and simulation models to make informed decisions in the planning of urban passenger transport. Designed UML diagram that describes the relationship of classes of the proposed model. A description of the main agents of the model developed in the simulation AnyLogic. Designed user interface integration with GIS map. Also provides simulation results that allow concluding about her health and the possibility of its use in solving planning problems of urban passenger transport.

  13. Regional analysis of groundwater phosphate concentrations under acidic sandy soils: Edaphic factors and water table strongly mediate the soil P-groundwater P relation.

    Science.gov (United States)

    Mabilde, Lisa; De Neve, Stefaan; Sleutel, Steven

    2017-12-01

    Historic long-term P application to sandy soils in NW-Europe has resulted in abundant sorption, saturation and eventually leaching of P from soil to the groundwater. Although many studies recognize the control of site-specific factors like soil texture and phosphate saturation degree (PSD), the regional-scaled relevance of effects exerted by single factors controlling P leaching is unclear. Very large observational datasets of soil and groundwater P content are furthermore required to reveal indirect controls of soil traits through mediating soil variables. We explored co-variation of phreatic groundwater orthophosphate (o-P) concentration and soil factors in sandy soils in Flanders, Belgium. Correlation analyses were complemented with an exploratory model derived using 'path analysis'. Data of oxalate-extractable Al, Fe, P and pH KCl , phosphate sorption capacity (PSC) and PSD in three depth layers (0-30, 30-60, 60-90 cm), topsoil SOC, % clay and groundwater depth (fluctuation) were interpolated to predict soil properties on exact locations of a very extensive net of groundwater monitoring wells. The mean PSD was only poorly correlated to groundwater o-P concentration, indicating the overriding control of other factors in the transport of P to the groundwater. A significant (P soil pH and groundwater table depth than by PSD indicates the likely oversimplification of the latter index to measure the long-term potential risk of P leaching. Accounting for controls on leaching not included in PSD via an alternative index, however, seems problematic as in Flanders for example groundwater o-P turned out to be higher in finer textured soils or soils with higher pedogenic Fe content, probably because of their lower pedogenic Al content and higher soil pH. Path analysis of extensive soil and groundwater datasets seems a viable way to identify prime local determinants of soil P leaching and could be further on used for 'ground-truthing' more complex P-migration simulation

  14. Groundwater flow analysis and dose rate estimates from releases to wells at a coastal site

    Energy Technology Data Exchange (ETDEWEB)

    Kattilakoski, E.; Suolanen, V. [VTT Energy, Espoo (Finland)

    2000-09-01

    In the groundwater flow modelling part of this work the effective dilution volume in the well scenario was estimated by means of transient simulations of groundwater flow and transport, which are coupled due to the varying salinity. Both deep, drilled wells and shallow surface wells in the vicinity of the repository were considered. The simulations covered the time period from the present to 1000 years after the present. Conceptually the fractured bedrock consists of planar fracture zones (with a high fracture density and a greater ability to conduct water) and the intact rock (in which the fracture density and the hydraulic conductivity are low). For them the equivalent-continuum model was applied separately. Thus, the fractured bedrock was considered as piecewise homogeneous (except for the depth dependence) and isotropic continuum with representative average characteristics. A generic simulation model for groundwater flow and solute transport was developed on the basis of geological, hydrogeological and hydrogeochemical data at a coastal area. The simulation model contains all the data necessary for the numerical simulations, i.e. the groundwater table and topography, salinity, the postglacial land uplift and sea level rise, the conceptual geometry of fracture zones, the hydraulic properties of the bedrock as well as the description of the modelling volume. The model comprises an area of about 26 km{sup 2}. It covers an island and the surrounding sea. The finite element code FEFTRA (formerly known as FEFLOW) was used in this work for the numerical solution. The channelling along the flow routes was found to be critical for the resulting in a well. A deep well may extend near the area of the deep flow routes, but in order to get flow routes into a shallow well, it has to be placed in the immediate vicinity of the discharge areas. According to the groundwater flow analyses the effective dilution volume of the well seems to vary from 30 000 m{sup 3}/a to 460 000 m

  15. Variable thickness transient ground-water flow model. Volume 3. Program listings

    International Nuclear Information System (INIS)

    Reisenauer, A.E.

    1979-12-01

    The Assessment of Effectiveness of Geologic Isolation Systems (AEGIS) Program is developing and applying the methodology for assessing the far-field, long-term post-closure safety of deep geologic nuclear waste repositories. AEGIS is being performed by Pacific Northwest Laboratory (PNL) under contract with the Office of Nuclear Waste Isolation (OWNI) for the Department of Energy (DOE). One task within AEGIS is the development of methodology for analysis of the consequences (water pathway) from loss of repository containment as defined by various release scenarios. Analysis of the long-term, far-field consequences of release scenarios requires the application of numerical codes which simulate the hydrologic systems, model the transport of released radionuclides through the hydrologic systems to the biosphere, and, where applicable, assess the radiological dose to humans. Hydrologic and transport models are available at several levels of complexity or sophistication. Model selection and use are determined by the quantity and quality of input data. Model development under AEGIS and related programs provides three levels of hydrologic models, two levels of transport models, and one level of dose models (with several separate models). This is the third of 3 volumes of the description of the VTT (Variable Thickness Transient) Groundwater Hydrologic Model - second level (intermediate complexity) two-dimensional saturated groundwater flow

  16. A compositional multiphase model for groundwater contamination by petroleum products: 2. Numerical solution

    Science.gov (United States)

    Baehr, Arthur L.; Corapcioglu, M. Yavuz

    1987-01-01

    In this paper we develop a numerical solution to equations developed in part 1 (M. Y. Corapcioglu and A. L. Baehr, this issue) to predict the fate of an immiscible organic contaminant such as gasoline in the unsaturated zone subsequent to plume establishment. This solution, obtained by using a finite difference scheme and a method of forward projection to evaluate nonlinear coefficients, provides estimates of the flux of solubilized hydrocarbon constituents to groundwater from the portion of a spill which remains trapped in a soil after routine remedial efforts to recover the product have ceased. The procedure was used to solve the one-dimensional (vertical) form of the system of nonlinear partial differential equations defining the transport for each constituent of the product. Additionally, a homogeneous, isothermal soil with constant water content was assumed. An equilibrium assumption partitions the constituents between air, water, adsorbed, and immiscible phases. Free oxygen transport in the soil was also simulated to provide an upper bound estimate of aerobic biodgradation rates. Results are presented for a hypothetical gasoline consisting of eight groups of hydrocarbon constituents. Rates at which hydrocarbon mass is removed from the soil, entering either the atmosphere or groundwater, or is biodegraded are presented. A significant sensitivity to model parameters, particularly the parameters characterizing diffusive vapor transport, was discovered. We conclude that hydrocarbon solute composition in groundwater beneath a gasoline contaminated soil would be heavily weighted toward aromatic constituents like benzene, toluene, and xylene.

  17. Computer simulation of transport driven current in tokamaks

    International Nuclear Information System (INIS)

    Nunan, W.J.; Dawson, J.M.

    1993-01-01

    Plasma transport phenomena can drive large currents parallel to an externally applied magnetic field. The Bootstrap Current Theory accounts for the effect of Banana diffusion on toroidal current, but the effect is not confined to that transport regime. The authors' 2 1/2-D, electromagnetic, particle simulations have demonstrated that Maxwellian plasmas in static toroidal and vertical fields spontaneously develop significant toroidal current, even in the absence of the open-quotes seed currentclose quotes which the Bootstrap Theory requires. Other simulations, in both toroidal and straight cylindrical geometries, and without any externally imposed electric field, show that if the plasma column is centrally fueled, and if the particle diffusion coefficient exceeds the magnetic diffusion coefficient (as is true in most tokamaks) then the toroidal current grows steadily. The simulations indicate that such fueling, coupled with central heating due to fusion reactions may drive all of the tokamak's toroidal current. The Bootstrap and dynamo mechanisms do not drive toroidal current where the poloidal magnetic field is zero. The simulations, as well as initial theoretical work, indicate that in tokamak plasmas, various processes naturally transport current from the outer regions of the plasma to the magnetic axis. The mechanisms which cause this effective electron viscosity include conventional binary collisions, wave emission and reabsorption, and also convection associated with rvec E x rvec B vortex motion. The simulations also exhibit preferential loss of particles carrying current opposing the bulk plasma current. This preferential loss generates current even at the magnetic axis. If these self-seeding mechanisms function in experiments as they do in the simulations, then transport driven current would eliminate the need for any external current drive in tokamaks, except simple ohmic heating for initial generation of the plasma

  18. Groundwater availability of the Mississippi embayment

    Science.gov (United States)

    Clark, Brian R.; Hart, Rheannon M.; Gurdak, Jason J.

    2011-01-01

    River Valley alluvial aquifer in Arkansas, Louisiana, Mississippi, and Missouri, and to a lesser extent in Illinois, Kentucky, and Tennessee. Predevelopment groundwater flow is represented in the MERAS model as a steady-state stress period, assumed to be prior to 1870. The simulated groundwater-flow budget indicates the largest predevelopment inflow to the system is net recharge to the alluvial aquifer. This inflow is balanced by outflow to gaining streams. Overall, water enters as net recharge to the alluvial aquifer or through outcrop areas of the various hydrogeologic units. Away from the outcrop areas, groundwater flow in the deeper formations is primarily upward into overlying units, ultimately discharging to streams through the alluvial aquifer. Total net recharge and discharge (sum of inflows or outflows) for the model ranged from about 0.66 million acre-feet per year during predevelopment to 20.16 million acre-feet per year by the end of the simulation (final simulated irrigation period in summer of 2006). This change in the model budget reflects increases in withdrawals compared to predevelopment conditions. Cumulative storage within aquifers simulated in the MERAS model indicates overall depletion of 140 million acre-feet (equivalent to 2.8 feet of water covering the entire study area). Postdevelopment inflow to the system is still through net recharge to the alluvial aquifer and the outcrop areas of the several hydrogeologic units, however, the flow between each unit is no longer upward to the alluvial aquifer. Groundwater flow during the summer of 2006 was primarily downward to offset demand from pumping. Early in the model simulation (1870-1920s), the primary components of the water budget were simulated as outflow from stream leakage and inflow from net recharge. As pumpage increased through time, water that would otherwise flow to streams reversed, and net stream leakage became an inflow to the system. The largest reversals began in the mid-1980s, but

  19. Modeling effects of nitrate from non-point sources on groundwater quality in an agricultural watershed in Prince Edward Island, Canada

    Science.gov (United States)

    Jiang, Yefang; Somers, George

    2009-05-01

    Intensification of potato farming has contaminated groundwater with nitrate in many cases in Prince Edward Island, Canada, which raises concerns for drinking water quality and associated ecosystem protection. Numerical models were developed to simulate nitrate-N transport in groundwater and enhance understanding of the impacts of farming on water quality in the Wilmot River watershed. Nitrate is assumed non-reactive based on δ15N and δ18O in nitrate and geochemical information. The source functions were reconstructed from tile drain measurements, N budget and historical land-use information. The transport model was calibrated to long-term nitrate-N observations in the Wilmot River and verified against nitrate-N measurements in two rivers from watersheds with similar physical conditions. Simulations show groundwater flow is stratified and vertical flux decreases exponentially with depth. While it would take several years to reduce the nitrate-N in the shallow portion of the aquifer, it would take several decades or even longer to restore water quality in the deeper portions of the aquifer. Elevated nitrate-N concentrations in base flow are positively correlated with potato cropping intensity and significant reductions in nitrate-N loading are required if the nitrate level of surface water is to recover to the standard in the Canadian Water Quality Guidelines.

  20. Numerical model to simulate the isotopic and heat release and transport through the geosphere from a geological repository of radioactive wastes; Un modelo numerico para la simulacion de transporte de calor y liberacion de materia en un almacenamiento profundo de residuos radiactivos

    Energy Technology Data Exchange (ETDEWEB)

    Hidalgo Lopez, A [Universidad Politecnica de Madrid (Spain)

    2002-07-01

    The aim of this research is to simulate the isotopic and heat release and transport through the geosphere, from a geological repository of high level nuclear waste. in order to achieve it, different physical processes, that have to do with the problem, are considered: groundwater flow, radioactive decay, nuclide dissolution in groundwater, heat generation, mass and heat transport. Some of these phenomena are related among the, which allows to build a coupled model,which is the starting point to generate a FORTRAN code. The flow and transport models are developed in two spatial dimensions and are integrated in space by means of a finite volume method. The time integration is fulfilled by a {theta}-method. Moreover, the advection-diffusion equation is solved by two finite volume techniques. In the first one a linear interpolation is used whereas in the second it is used a quadratic one. Also, a consistency an stability study of both methods is carried out in order to compare their stability zones and the errors appearing. Stability is analysed by applying the von Neumann method, which is based upon Fourier series. Although it is a classical technique when dealing with finite-difference schemes, it is here applied to two finite volume schemes. (Author)

  1. Evaluation of groundwater flow and transport at the Shoal underground nuclear test: An interim report

    International Nuclear Information System (INIS)

    Pohll, G.; Chapman, J.; Hassan, A.; Papelis, C.; Andricevic, R.; Shirley, C.

    1998-07-01

    Since 1962, all United States nuclear tests have been conducted underground. A consequence of this testing has been the deposition of large amounts of radioactive materials in the subsurface, sometimes in direct contact with groundwater. The majority of this testing occurred on the Nevada Test Site, but a limited number of experiments were conducted in other locations. One of these is the subject of this report, the Project Shoal Area (PSA), located about 50 km southeast of Fallon, Nevada. The Shoal test consisted of a 12-kiloton-yield nuclear detonation which occurred on October 26, 1963. Project Shoal was part of studies to enhance seismic detection of underground nuclear tests, in particular, in active earthquake areas. Characterization of groundwater contamination at the Project Shoal Area is being conducted by the US Department of Energy (DOE) under the Federal Facility Agreement and Consent Order (FFACO) with the State of Nevada Department of Environmental Protection and the US Department of Defense (DOD). This order prescribes a Corrective Action Strategy (Appendix VI), which, as applied to underground nuclear tests, involves preparing a Corrective Action Investigation Plan (CAIP), Corrective Action Decision Document (CADD), Corrective Action Plan, and Closure Report. The scope of the CAIP is flow and transport modeling to establish contaminant boundaries that are protective of human health and the environment. This interim report describes the current status of the flow and transport modeling for the PSA

  2. Evaluation of groundwater flow and transport at the Shoal underground nuclear test: An interim report

    Energy Technology Data Exchange (ETDEWEB)

    Pohll, G.; Chapman, J.; Hassan, A.; Papelis, C.; Andricevic, R.; Shirley, C.

    1998-07-01

    Since 1962, all United States nuclear tests have been conducted underground. A consequence of this testing has been the deposition of large amounts of radioactive materials in the subsurface, sometimes in direct contact with groundwater. The majority of this testing occurred on the Nevada Test Site, but a limited number of experiments were conducted in other locations. One of these is the subject of this report, the Project Shoal Area (PSA), located about 50 km southeast of Fallon, Nevada. The Shoal test consisted of a 12-kiloton-yield nuclear detonation which occurred on October 26, 1963. Project Shoal was part of studies to enhance seismic detection of underground nuclear tests, in particular, in active earthquake areas. Characterization of groundwater contamination at the Project Shoal Area is being conducted by the US Department of Energy (DOE) under the Federal Facility Agreement and Consent Order (FFACO) with the State of Nevada Department of Environmental Protection and the US Department of Defense (DOD). This order prescribes a Corrective Action Strategy (Appendix VI), which, as applied to underground nuclear tests, involves preparing a Corrective Action Investigation Plan (CAIP), Corrective Action Decision Document (CADD), Corrective Action Plan, and Closure Report. The scope of the CAIP is flow and transport modeling to establish contaminant boundaries that are protective of human health and the environment. This interim report describes the current status of the flow and transport modeling for the PSA.

  3. Simulation of electron thermal transport in H-mode discharges

    International Nuclear Information System (INIS)

    Rafiq, T.; Pankin, A. Y.; Bateman, G.; Kritz, A. H.; Halpern, F. D.

    2009-01-01

    Electron thermal transport in DIII-D H-mode tokamak plasmas [J. L. Luxon, Nucl. Fusion 42, 614 (2002)] is investigated by comparing predictive simulation results for the evolution of electron temperature profiles with experimental data. The comparison includes the entire profile from the magnetic axis to the bottom of the pedestal. In the simulations, carried out using the automated system for transport analysis (ASTRA) integrated modeling code, different combinations of electron thermal transport models are considered. The combinations include models for electron temperature gradient (ETG) anomalous transport and trapped electron mode (TEM) anomalous transport, as well as a model for paleoclassical transport [J. D. Callen, Nucl. Fusion 45, 1120 (2005)]. It is found that the electromagnetic limit of the Horton ETG model [W. Horton et al., Phys. Fluids 31, 2971 (1988)] provides an important contribution near the magnetic axis, which is a region where the ETG mode in the GLF23 model [R. E. Waltz et al., Phys. Plasmas 4, 2482 (1997)] is below threshold. In simulations of DIII-D discharges, the observed shape of the H-mode edge pedestal is produced when transport associated with the TEM component of the GLF23 model is suppressed and transport given by the paleoclassical model is included. In a study involving 15 DIII-D H-mode discharges, it is found that with a particular combination of electron thermal transport models, the average rms deviation of the predicted electron temperature profile from the experimental profile is reduced to 9% and the offset to -4%.

  4. Synthetic Sediments and Stochastic Groundwater Hydrology

    Science.gov (United States)

    Wilson, J. L.

    2002-12-01

    For over twenty years the groundwater community has pursued the somewhat elusive goal of describing the effects of aquifer heterogeneity on subsurface flow and chemical transport. While small perturbation stochastic moment methods have significantly advanced theoretical understanding, why is it that stochastic applications use instead simulations of flow and transport through multiple realizations of synthetic geology? Allan Gutjahr was a principle proponent of the Fast Fourier Transform method for the synthetic generation of aquifer properties and recently explored new, more geologically sound, synthetic methods based on multi-scale Markov random fields. Focusing on sedimentary aquifers, how has the state-of-the-art of synthetic generation changed and what new developments can be expected, for example, to deal with issues like conceptual model uncertainty, the differences between measurement and modeling scales, and subgrid scale variability? What will it take to get stochastic methods, whether based on moments, multiple realizations, or some other approach, into widespread application?

  5. Numerical calculations on heterogeneity of groundwater flow

    International Nuclear Information System (INIS)

    Follin, S.

    1992-01-01

    The upscaling of model parameters is a key issue in many research fields concerned with parameter heterogeneity. The upscaling process allows for fewer model blocks and relaxes the numerical problems caused by high contrasts in the hydraulic conductivity. The trade-offs are dependent on the object but the general drawback is an increasing uncertainty about the representativeness. The present study deals with numerical calculations of heterogeneity of groundwater flow and solute transport in hypothetical blocks of fractured hard rock in a '3m scale' and addresses both conceptual and practical problems in numerical simulation. Evidence that the hydraulic conductivity (K) of the rock mass between major fracture zones is highly heterogeneous in a 3m scale is provided by a large number of field investigations. The present uses the documented heterogeneity and investigates flow and transport in a two-dimensional stochastic continuum characterized by a variance in Y = In(K) of σ y 2 = 16, corresponding to about 12 log 10 cycles in K. The study considers anisotropy, channelling, non-Fickian and Fickian transport, and conditional simulation. The major conclusions are: * heterogeneity gives rise to anisotropy in the upscaling process, * the choice of support scale is crucial for the modelling of solute transport. As a consequence of the obtained results, a two-dimensional stochastic discontinuum model is presented, which provides a tool for linking stochastic continuum models to discrete fracture network models. (au) (14 figs., 136 refs.)

  6. Numerical simulation of freshwater/seawater interaction in a dual-permeability karst system with conduits: the development of discrete-continuum VDFST-CFP model

    Science.gov (United States)

    Xu, Zexuan; Hu, Bill

    2016-04-01

    Dual-permeability karst aquifers of porous media and conduit networks with significant different hydrological characteristics are widely distributed in the world. Discrete-continuum numerical models, such as MODFLOW-CFP and CFPv2, have been verified as appropriate approaches to simulate groundwater flow and solute transport in numerical modeling of karst hydrogeology. On the other hand, seawater intrusion associated with fresh groundwater resources contamination has been observed and investigated in numbers of coastal aquifers, especially under conditions of sea level rise. Density-dependent numerical models including SEAWAT are able to quantitatively evaluate the seawater/freshwater interaction processes. A numerical model of variable-density flow and solute transport - conduit flow process (VDFST-CFP) is developed to provide a better description of seawater intrusion and submarine groundwater discharge in a coastal karst aquifer with conduits. The coupling discrete-continuum VDFST-CFP model applies Darcy-Weisbach equation to simulate non-laminar groundwater flow in the conduit system in which is conceptualized and discretized as pipes, while Darcy equation is still used in continuum porous media. Density-dependent groundwater flow and solute transport equations with appropriate density terms in both conduit and porous media systems are derived and numerically solved using standard finite difference method with an implicit iteration procedure. Synthetic horizontal and vertical benchmarks are created to validate the newly developed VDFST-CFP model by comparing with other numerical models such as variable density SEAWAT, couplings of constant density groundwater flow and solute transport MODFLOW/MT3DMS and discrete-continuum CFPv2/UMT3D models. VDFST-CFP model improves the simulation of density dependent seawater/freshwater mixing processes and exchanges between conduit and matrix. Continuum numerical models greatly overestimated the flow rate under turbulent flow

  7. Hydrogeology and simulation of ground-water flow, Picatinny Arsenal and vicinity, Morris County, New Jersey

    Science.gov (United States)

    Voronin, L.M.; Rice, D.E.

    1996-01-01

    Ground-water flow in glacial sediments and bedrock at Picatinny Arsenal, N.J., was simulated by use of a three-dimensional finite-difference ground- water-flow model. The modeled area includes a 4.3-square-mile area that extends from Picatinny Lake to the Rockaway River. Most of the study area is bounded by the natural hydrologic boundaries of the ground-water system. eophysical logs, lithologic logs, particle-size data, and core data from selected wells and surface geophysical data were analyzed to define the hydrogeologic framework. Hydrogeologic sections and thickness maps define six permeable and three low-permeability layers that are represented in the model as aquifers and confining units, respectively. Hydrologic data incorporated in the model include a rate of recharge from precipitation of 22 inches per year, estimated from long-term precipitation records and estimates of evapotranspiration. Additional recharge from infiltration along valleys was estimated from measured discharge of springs along the adjacent valley walls and from estimates of runoff from upland drainage that flows to the valley floor. Horizontal and vertical hydraulic conductivities of permeable and low-permeability layers were estimated from examination of aquifer-test data, gamma-ray logs, borehole cuttings, and previously published data. Horizontal hydraulic conductivities in glacial sediments range from 10 to 380 feet per day. Vertical hydraulic conductivities of the low-permeability layers range from 0.01 to 0.7 feet per day. The model was calibrated by simulating steady-state conditions during 1989-93 and by closely matching simulated and measured ground-water levels, vertical ground-water-head differences, and streamflow gain and loss. Simulated steady-state potentiometric- surface maps produced for the six permeable layers indicate that ground water in the unconfined material within Picatinny Arsenal flows predominantly toward the center of the valley, where it discharges to Green

  8. Simulation study of the chemical forms of neptunium and plutonium in groundwater from a borehole in the northwest region

    International Nuclear Information System (INIS)

    Ma Yingming; Jin Yuren; Wang Zhiqiang; Liu Dongxu; Liu Wei; Liu Yan

    2009-01-01

    According to physics-chymistry characteristic of groundwater from a borehole in the northwest region, we performed simulation study of the chemical forms of neptunium and plutonium by the geochemistry modeling program EQ3/6. The main conclusions are as follows: the main chemical form of neptunium in the groundwater is Np(V)'s NpO 2 + , subordination chemical forms are NpO 2 Cl, NpO 2 CO 3 - , NpO 2 OH, NpO 2 SO 4 - ; the main existing form of plutonium in the groundwater is Pu(IV)'s Pu(OH)5-and subordination chemical form is Pu(V)'s PuO 2 + . In addition,the temperature, pH and Eh also have different impacts on the chemical form of neptunium and plutonium. (authors)

  9. CFEST Coupled Flow, Energy & Solute Transport Version CFEST005 User’s Guide

    Energy Technology Data Exchange (ETDEWEB)

    Freedman, Vicky L.; Chen, Yousu; Gilca, Alex; Cole, Charles R.; Gupta, Sumant K.

    2006-07-20

    The CFEST (Coupled Flow, Energy, and Solute Transport) simulator described in this User’s Guide is a three-dimensional finite-element model used to evaluate groundwater flow and solute mass transport. Confined and unconfined aquifer systems, as well as constant and variable density fluid flows can be represented with CFEST. For unconfined aquifers, the model uses a moving boundary for the water table, deforming the numerical mesh so that the uppermost nodes are always at the water table. For solute transport, changes in concentra¬tion of a single dissolved chemical constituent are computed for advective and hydrodynamic transport, linear sorption represented by a retardation factor, and radioactive decay. Although several thermal parameters described in this User’s Guide are required inputs, thermal transport has not yet been fully implemented in the simulator. Once fully implemented, transport of thermal energy in the groundwater and solid matrix of the aquifer can also be used to model aquifer thermal regimes. The CFEST simulator is written in the FORTRAN 77 language, following American National Standards Institute (ANSI) standards. Execution of the CFEST simulator is controlled through three required text input files. These input file use a structured format of associated groups of input data. Example input data lines are presented for each file type, as well as a description of the structured FORTRAN data format. Detailed descriptions of all input requirements, output options, and program structure and execution are provided in this User’s Guide. Required inputs for auxillary CFEST utilities that aide in post-processing data are also described. Global variables are defined for those with access to the source code. Although CFEST is a proprietary code (CFEST, Inc., Irvine, CA), the Pacific Northwest National Laboratory retains permission to maintain its own source, and to distribute executables to Hanford subcontractors.

  10. Simulation of transportation of low enriched uranium solutions

    International Nuclear Information System (INIS)

    Hope, E.P.; Ades, M.J.

    1996-01-01

    A simulation of the transportation by truck of low enriched uranium solutions has been completed for NEPA purposes at the Savannah River Site. The analysis involves three distinct source terms, and establishes the radiological risks of shipment to three possible destinations. Additionally, loading accidents were analyzed to determine the radiological consequences of mishaps during handling and delivery. Source terms were developed from laboratory measurements of chemical samples from low enriched uranium feed materials being stored at SRS facilities, and from manufacturer data on transport containers. The transportation simulations were accomplished over the INTERNET using the DOE TRANSNET system at Sandia National Laboratory. The HIGHWAY 3.3 code was used to analyze routing scenarios, and the RADTRAN 4 code was used to analyze incident free and accident risks of transporting radiological materials. Loading accidents were assessed using the Savannah River Site AXAIR89Q and RELEASE 2 codes

  11. Simulation and assessment of groundwater flow and groundwater and surface-water exchanges in lakes of the northeast Twin Cities Metropolitan Area, Minnesota, 2003 through 2013: Chapter B of Water levels and groundwater and surface-water exchanges in lakes of the northeast Twin Cities Metropolitan Area, Minnesota, 2002 through 2015

    Science.gov (United States)

    Jones, Perry M.; Roth, Jason L.; Trost, Jared J.; Christenson, Catherine A.; Diekoff, Aliesha L.; Erickson, Melinda L.

    2017-09-05

    Water levels during 2003 through 2013 were less than mean water levels for the period 1925–2013 for several lakes in the northeast Twin Cities Metropolitan Area in Minnesota. Previous periods of low lake-water levels generally were correlated with periods with less than mean precipitation. Increases in groundwater withdrawals and land-use changes have brought into question whether or not recent (2003–13) lake-water-level declines are solely caused by decreases in precipitation. A thorough understanding of groundwater and surface-water exchanges was needed to assess the effect of water-management decisions on lake-water levels. To address this need, the U.S. Geological Survey, in cooperation with the Metropolitan Council and the Minnesota Department of Health, developed and calibrated a three-dimensional, steady-state groundwater-flow model representing 2003–13 mean hydrologic conditions to assess groundwater and lake-water exchanges, and the effects of groundwater withdrawals and precipitation on water levels of 96 lakes in the northeast Twin Cities Metropolitan Area.Lake-water budgets for the calibrated groundwater-flow model indicated that groundwater is flowing into lakes in the northeast Twin Cities Metropolitan Area and lakes are providing water to underlying aquifers. Lake-water outflow to the simulated groundwater system was a major outflow component for Big Marine Lake, Lake Elmo, Snail Lake, and White Bear Lake, accounting for 45 to 64 percent of the total outflows from the lakes. Evaporation and transpiration from the lake surface ranged from 19 to 52 percent of the total outflow from the four lakes. Groundwater withdrawals and precipitation were varied from the 2003‒13 mean values used in the calibrated model (30-percent changes in groundwater withdrawals and 5-percent changes in precipitation) for hypothetical scenarios to assess the effects of groundwater withdrawals and precipitation on water budgets and levels in Big Marine Lake, Snail Lake

  12. Groundwater flow modelling of periods with periglacial and glacial climate conditions - Forsmark

    International Nuclear Information System (INIS)

    Vidstrand, Patrik; Follin, Sven; Zugec, Nada

    2010-12-01

    As a part of the license application for a final repository for spent nuclear fuel at Forsmark, the Swedish Nuclear Fuel and Waste Management Company (SKB) has undertaken a series of groundwater flow modelling studies. These represent time periods with different hydraulic conditions and the simulations carried out contribute to the overall evaluation of the repository design and long-term radiological safety. The groundwater flow modelling study reported here comprises a coupled thermal-hydraulic-chemical (T-H-C) analysis of periods with periglacial and glacial climate conditions. Hydraulic-mechanical (H-M) issues are also handled but no coupled flow modelling is done. The objective of the report is to provide bounding hydrogeological estimates at different stages during glaciation and deglaciation of a glacial cycle for subsequent use in safety assessment applications within SKB's project SR-Site. Three cases with different climate conditions are analysed here: (i) Temperate case, (ii) Glacial case without permafrost, and (iii) Glacial case with permafrost. The glacial periods are transient and encompass approximately 19,000 years. The simulation results comprise residual fluid pressures, Darcy fluxes, and water salinities, as well as advective transport performance measures obtained by particle tracking such as flow path lengths, travel times and flow-related transport resistances. The modelling is accompanied by a sensitivity study that addresses the impact of the following matters: the direction of the ice sheet advance, the speed of the ice sheet margin, the bedrock hydraulic and transport properties, the temperature at the ice-subsurface interface close to the ice sheet margin, and the initial hydrochemical conditions

  13. Groundwater flow modelling of periods with periglacial and glacial climate conditions - Forsmark

    Energy Technology Data Exchange (ETDEWEB)

    Vidstrand, Patrik (TerraSolve AB, Floda (Sweden)); Follin, Sven (SF GeoLogic AB, Taeby (Sweden)); Zugec, Nada (Bergab, Stockholm (Sweden))

    2010-12-15

    As a part of the license application for a final repository for spent nuclear fuel at Forsmark, the Swedish Nuclear Fuel and Waste Management Company (SKB) has undertaken a series of groundwater flow modelling studies. These represent time periods with different hydraulic conditions and the simulations carried out contribute to the overall evaluation of the repository design and long-term radiological safety. The groundwater flow modelling study reported here comprises a coupled thermal-hydraulic-chemical (T-H-C) analysis of periods with periglacial and glacial climate conditions. Hydraulic-mechanical (H-M) issues are also handled but no coupled flow modelling is done. The objective of the report is to provide bounding hydrogeological estimates at different stages during glaciation and deglaciation of a glacial cycle for subsequent use in safety assessment applications within SKB's project SR-Site. Three cases with different climate conditions are analysed here: (i) Temperate case, (ii) Glacial case without permafrost, and (iii) Glacial case with permafrost. The glacial periods are transient and encompass approximately 19,000 years. The simulation results comprise residual fluid pressures, Darcy fluxes, and water salinities, as well as advective transport performance measures obtained by particle tracking such as flow path lengths, travel times and flow-related transport resistances. The modelling is accompanied by a sensitivity study that addresses the impact of the following matters: the direction of the ice sheet advance, the speed of the ice sheet margin, the bedrock hydraulic and transport properties, the temperature at the ice-subsurface interface close to the ice sheet margin, and the initial hydrochemical conditions.

  14. Review: Regional land subsidence accompanying groundwater extraction

    Science.gov (United States)

    Galloway, Devin L.; Burbey, Thomas J.

    2011-01-01

    The extraction of groundwater can generate land subsidence by causing the compaction of susceptible aquifer systems, typically unconsolidated alluvial or basin-fill aquifer systems comprising aquifers and aquitards. Various ground-based and remotely sensed methods are used to measure and map subsidence. Many areas of subsidence caused by groundwater pumping have been identified and monitored, and corrective measures to slow or halt subsidence have been devised. Two principal means are used to mitigate subsidence caused by groundwater withdrawal—reduction of groundwater withdrawal, and artificial recharge. Analysis and simulation of aquifer-system compaction follow from the basic relations between head, stress, compressibility, and groundwater flow and are addressed primarily using two approaches—one based on conventional groundwater flow theory and one based on linear poroelasticity theory. Research and development to improve the assessment and analysis of aquifer-system compaction, the accompanying subsidence and potential ground ruptures are needed in the topic areas of the hydromechanical behavior of aquitards, the role of horizontal deformation, the application of differential synthetic aperture radar interferometry, and the regional-scale simulation of coupled groundwater flow and aquifer-system deformation to support resource management and hazard mitigation measures.

  15. Numerical modeling of solute transport in a sand tank physical model under varying hydraulic gradient and hydrological stresses

    Science.gov (United States)

    Atlabachew, Abunu; Shu, Longcang; Wu, Peipeng; Zhang, Yongjie; Xu, Yang

    2018-03-01

    This laboratory study improves the understanding of the impacts of horizontal hydraulic gradient, artificial recharge, and groundwater pumping on solute transport through aquifers. Nine experiments and numerical simulations were carried out using a sand tank. The variable-density groundwater flow and sodium chloride transport were simulated using the three-dimensional numerical model SEAWAT. Numerical modelling results successfully reproduced heads and concentrations observed in the sand tank. A higher horizontal hydraulic gradient enhanced the migration of sodium chloride, particularly in the groundwater flow direction. The application of constant artificial recharge increased the spread of the sodium chloride plume in both the longitudinal and lateral directions. In addition, groundwater pumping accelerated spreading of the sodium chloride plume towards the pumping well. Both higher hydraulic gradient and pumping rate generated oval-shaped plumes in the horizontal plane. However, the artificial recharge process produced stretched plumes. These effects of artificial recharge and groundwater pumping were greater under higher hydraulic gradient. The concentration breakthrough curves indicated that emerging solutions never attained the concentration of the originally injected solution. This is probably because of sorption of sodium chloride onto the silica sand and/or the exchange of sodium chloride between the mobile and immobile liquid domains. The fingering and protruding plume shapes in the numerical models constitute instability zones produced by buoyancy-driven flow. Overall, the results have substantiated the influences of hydraulic gradient, boundary condition, artificial recharge, pumping rate and density differences on solute transport through a homogeneous unconfined aquifer. The implications of these findings are important for managing liquid wastes.

  16. Tight-coupling of groundwater flow and transport modelling engines with spatial databases and GIS technology: a new approach integrating Feflow and ArcGIS

    Directory of Open Access Journals (Sweden)

    Ezio Crestaz

    2012-09-01

    Full Text Available Implementation of groundwater flow and transport numerical models is generally a challenge, time-consuming and financially-demanding task, in charge to specialized modelers and consulting firms. At a later stage, within clearly stated limits of applicability, these models are often expected to be made available to less knowledgeable personnel to support/design and running of predictive simulations within more familiar environments than specialized simulation systems. GIS systems coupled with spatial databases appear to be ideal candidates to address problem above, due to their much wider diffusion and expertise availability. Current paper discusses the issue from a tight-coupling architecture perspective, aimed at integration of spatial databases, GIS and numerical simulation engines, addressing both observed and computed data management, retrieval and spatio-temporal analysis issues. Observed data can be migrated to the central database repository and then used to set up transient simulation conditions in the background, at run time, while limiting additional complexity and integrity failure risks as data duplication during data transfer through proprietary file formats. Similarly, simulation scenarios can be set up in a familiar GIS system and stored to spatial database for later reference. As numerical engine is tightly coupled with the GIS, simulations can be run within the environment and results themselves saved to the database. Further tasks, as spatio-temporal analysis (i.e. for postcalibration auditing scopes, cartography production and geovisualization, can then be addressed using traditional GIS tools. Benefits of such an approach include more effective data management practices, integration and availability of modeling facilities in a familiar environment, streamlining spatial analysis processes and geovisualization requirements for the non-modelers community. Major drawbacks include limited 3D and time-dependent support in

  17. Construction and calibration of a groundwater-flow model to assess groundwater availability in the uppermost principal aquifer systems of the Williston Basin, United States and Canada

    Science.gov (United States)

    Davis, Kyle W.; Long, Andrew J.

    2018-05-31

    The U.S. Geological Survey developed a groundwater-flow model for the uppermost principal aquifer systems in the Williston Basin in parts of Montana, North Dakota, and South Dakota in the United States and parts of Manitoba and Saskatchewan in Canada as part of a detailed assessment of the groundwater availability in the area. The assessment was done because of the potential for increased demands and stresses on groundwater associated with large-scale energy development in the area. As part of this assessment, a three-dimensional groundwater-flow model was developed as a tool that can be used to simulate how the groundwater-flow system responds to changes in hydrologic stresses at a regional scale.The three-dimensional groundwater-flow model was developed using the U.S. Geological Survey’s numerical finite-difference groundwater model with the Newton-Rhapson solver, MODFLOW–NWT, to represent the glacial, lower Tertiary, and Upper Cretaceous aquifer systems for steady-state (mean) hydrological conditions for 1981‒2005 and for transient (temporally varying) conditions using a combination of a steady-state period for pre-1960 and transient periods for 1961‒2005. The numerical model framework was constructed based on existing and interpreted hydrogeologic and geospatial data and consisted of eight layers. Two layers were used to represent the glacial aquifer system in the model; layer 1 represented the upper one-half and layer 2 represented the lower one-half of the glacial aquifer system. Three layers were used to represent the lower Tertiary aquifer system in the model; layer 3 represented the upper Fort Union aquifer, layer 4 represented the middle Fort Union hydrogeologic unit, and layer 5 represented the lower Fort Union aquifer. Three layers were used to represent the Upper Cretaceous aquifer system in the model; layer 6 represented the upper Hell Creek hydrogeologic unit, layer 7 represented the lower Hell Creek aquifer, and layer 8 represented the Fox

  18. Fracture network modeling and GoldSim simulation support

    International Nuclear Information System (INIS)

    Sugita, Kenichirou; Dershowitz, W.

    2005-01-01

    During Heisei-16, Golder Associates provided support for JNC Tokai through discrete fracture network data analysis and simulation of the Mizunami Underground Research Laboratory (MIU), participation in Task 6 of the AEspoe Task Force on Modeling of Groundwater Flow and Transport, and development of methodologies for analysis of repository site characterization strategies and safety assessment. MIU support during H-16 involved updating the H-15 FracMan discrete fracture network (DFN) models for the MIU shaft region, and developing improved simulation procedures. Updates to the conceptual model included incorporation of 'Step2' (2004) versions of the deterministic structures, and revision of background fractures to be consistent with conductive structure data from the DH-2 borehole. Golder developed improved simulation procedures for these models through the use of hybrid discrete fracture network (DFN), equivalent porous medium (EPM), and nested DFN/EPM approaches. For each of these models, procedures were documented for the entire modeling process including model implementation, MMP simulation, and shaft grouting simulation. Golder supported JNC participation in Task 6AB, 6D and 6E of the AEspoe Task Force on Modeling of Groundwater Flow and Transport during H-16. For Task 6AB, Golder developed a new technique to evaluate the role of grout in performance assessment time-scale transport. For Task 6D, Golder submitted a report of H-15 simulations to SKB. For Task 6E, Golder carried out safety assessment time-scale simulations at the block scale, using the Laplace Transform Galerkin method. During H-16, Golder supported JNC's Total System Performance Assessment (TSPA) strategy by developing technologies for the analysis of the use site characterization data in safety assessment. This approach will aid in the understanding of the use of site characterization to progressively reduce site characterization uncertainty. (author)

  19. The effects of model complexity and calibration period on groundwater recharge simulations

    Science.gov (United States)

    Moeck, Christian; Van Freyberg, Jana; Schirmer, Mario

    2017-04-01

    A significant number of groundwater recharge models exist that vary in terms of complexity (i.e., structure and parametrization). Typically, model selection and conceptualization is very subjective and can be a key source of uncertainty in the recharge simulations. Another source of uncertainty is the implicit assumption that model parameters, calibrated over historical periods, are also valid for the simulation period. To the best of our knowledge there is no systematic evaluation of the effect of the model complexity and calibration strategy on the performance of recharge models. To address this gap, we utilized a long-term recharge data set (20 years) from a large weighting lysimeter. We performed a differential split sample test with four groundwater recharge models that vary in terms of complexity. They were calibrated using six calibration periods with climatically contrasting conditions in a constrained Monte Carlo approach. Despite the climatically contrasting conditions, all models performed similarly well during the calibration. However, during validation a clear effect of the model structure on model performance was evident. The more complex, physically-based models predicted recharge best, even when calibration and prediction periods had very different climatic conditions. In contrast, more simplistic soil-water balance and lumped model performed poorly under such conditions. For these models we found a strong dependency on the chosen calibration period. In particular, our analysis showed that this can have relevant implications when using recharge models as decision-making tools in a broad range of applications (e.g. water availability, climate change impact studies, water resource management, etc.).

  20. A GIS-Enabled, Michigan-Specific, Hierarchical Groundwater Modeling and Visualization System

    Science.gov (United States)

    Liu, Q.; Li, S.; Mandle, R.; Simard, A.; Fisher, B.; Brown, E.; Ross, S.

    2005-12-01

    , automatically extract data and attributes, and simulate unsteady groundwater flow and contaminant transport in response to water and land management decisions; * Visualize and map model simulations and predictions with data from the statewide groundwater database in a seamless interactive environment. IGW-M has the potential to significantly improve the productivity of Michigan groundwater management investigations. It changes the role of engineers and scientists in modeling and analyzing the statewide groundwater database from heavily physical to cognitive problem-solving and decision-making tasks. The seamless real-time integration, real-time visual interaction, and real-time processing capability allows a user to focus on critical management issues, conflicts, and constraints, to quickly and iteratively examine conceptual approximations, management and planning scenarios, and site characterization assumptions, to identify dominant processes, to evaluate data worth and sensitivity, and to guide further data-collection activities. We illustrate the power and effectiveness of the M-IGW modeling and visualization system with a real case study and a real-time, live demonstration.

  1. A Mathematical Model for Simulating Remediation of Groundwater Contaminated by Heavy Metals using Bio-Carriers with Dead Baccilus sp. B1 and Polysulfone

    Science.gov (United States)

    Seo, H.; Wang, S.; Lee, M.

    2010-12-01

    The remediation of groundwater contaminated by heavy metals, organic contaminants, etc. using various types of bio-carriers has been widely studied as a novel technology in the literature. In this study, a series of batch experiments were conducted to investigated the fundamental characteristics in the removal process using bio-carriers (beads) with dead Bacillus sp. B1 and polysulfone. Through equilibrium and kinetic sorption experiments, sorption efficiencies for lead and copper under various conditions such as pH, temperature, contaminant concentration, etc. were examined and sorption parameters including maximum sorption capacities were obtained for model applications. Experimental data showed that equilibrium sorption patterns for Pb2+and Cu2+on bio-carrier beads follows Langmuir sorption isotherm and that the sorption dynamics can be described with a pseudo-second-order kinetics. One dimensional advective-dispersive-reactive transport model was also developed for simulating and analyzing the remediation processes. The HSDM (homogeneous surface diffusion model) were incorporated in the model to take into account the mass transfer and sorption mechanisms around/inside the bio-carrier beads. Applying the proposed model, numerical column experiments were carried out and the simulation results reasonably described temporal and spatial distribution of Pb2+and Cu2+in a fixed-bed flow-through sorption column. Experimental and numerical results showed that the main mechanism of the bio-carrier to remove heavy metals is the sorption on/inside of the bio-carriers and the bio-carriers can function as excellent biosorbents for the removal of heavy metal ions from groundwater.

  2. Quantification of long-term wastewater fluxes at the surface water/groundwater-interface: an integrative model perspective using stable isotopes and acesulfame.

    Science.gov (United States)

    Engelhardt, I; Barth, J A C; Bol, R; Schulz, M; Ternes, T A; Schüth, C; van Geldern, R

    2014-01-01

    The suitability of acesulfame to trace wastewater-related surface water fluxes from streams into the hyporheic and riparian zones over long-term periods was investigated. The transport behavior of acesulfame was compared with the transport of water stable isotopes (δ(18)O or δ(2)H). A calibrated model based on a joint inversion of temperature, acesulfame, and piezometric pressure heads was employed in a model validation using data sets of acesulfame and water stable isotopes collected over 5months in a stream and groundwater. The spatial distribution of fresh water within the groundwater resulting from surface water infiltration was estimated by computing groundwater ages and compared with the predicted acesulfame plume obtained after 153day simulation time. Both, surface water ratios calculated with a mixing equation from water stable isotopes and simulated acesulfame mass fluxes, were investigated for their ability to estimate the contribution of wastewater-related surface water inflow within groundwater. The results of this study point to limitations for the application of acesulfame to trace surface water-groundwater interactions properly. Acesulfame completely missed the wastewater-related surface water volumes that still remained in the hyporheic zone under stream-gaining conditions. In contrast, under stream-losing conditions, which developed after periods of stagnating hydraulic exchange, acesulfame based predictions lead to an overestimation of the surface water volume of up to 25% in the riparian zone. If slow seepage velocities prevail a proportion of acesulfame might be stored in smaller pores, while when released under fast flowing water conditions it will travel further downstream with the groundwater flow direction. Therefore, under such conditions acesulfame can be a less-ideal tracer in the hyporheic and riparian zones and additional monitoring with other environmental tracers such as water stable isotopes is highly recommended. © 2013 Elsevier

  3. FREESURF: A three-dimensional finite-element model for simulating groundwater flow into and around an excavation

    Energy Technology Data Exchange (ETDEWEB)

    Weitzman, Morley

    1992-07-15

    A three-dimensional finite-element code was developed and used to simulate the flow of groundwater towards an excavation in a saturated porous medium, allowing for seepage faces. An iterative procedure was used to predict the movement of the water table and the seepage flux. The numerical solution agreed well with experimental results from a sandbox experiment. (auth)

  4. Groundwater sustainability assessment in coastal aquifers

    Indian Academy of Sciences (India)

    The present work investigates the response of shallow, coastal unconfined aquifers to anticipated overdraft conditions and climate change effect using numerical simulation. The groundwater flow model MODFLOW and variable density groundwater model SEAWAT are used for this investigation. The transmissivity and ...

  5. The Ozark Plateaus Regional Aquifer Study—Documentation of a groundwater-flow model constructed to assess water availability in the Ozark Plateaus

    Science.gov (United States)

    Clark, Brian R.; Richards, Joseph M.; Knierim, Katherine J.

    2018-03-30

    Recent short-term drought conditions have emphasized the need to better understand the delicate balance between abundance, sustainability, and scarcity of groundwater in the Ozark Plateaus aquifer system. In 2014, the U.S. Geological Survey began construction of a groundwater-flow model as a tool for the assessment of groundwater availability in the Ozark Plateaus aquifer system. The model was developed to benefit concurrent and future investigations involving groundwater-pumping scenarios, optimization, particle transport, and groundwater-monitoring network analysis.The groundwater model simulates 116 years (1900–2015) of hydrologic conditions and the response of the groundwater system to changes in stress including changes in recharge and groundwater pumping for water supply. Semiseasonal stress periods were simulated from the later part of 1991 to 2015 and represent higher demand and lower recharge in the spring and summer months and lower demand and higher recharge in the fall and winter months. Groundwater pumping increases throughout the simulation period with a maximum rate of about 600 million gallons per day (Mgal/d).The process of matching historical hydrologic data for the Ozark Plateaus aquifer system model was accomplished by a combination of manual changes to parameter values and automated calibration methods. Observation data used in the development and evaluation of the model included 19,045 hydraulic-head observations from 6,683 wells within the model area. Observation data also included stream leakage estimates summed to calculate a net gain or net loss value for approximately 81 named streams.The majority (mean of over 95 percent) of the recharge component is discharged through streams simulated in the model. The total simulated discharge to streams fluctuates seasonally between 7,500 and 17,500 Mgal/d with a mean outflow of 11,500 Mgal/d. Much of the remaining balance between modeled recharge inflows and stream outflows is made up by water

  6. Simulating charge transport in flexible systems

    Directory of Open Access Journals (Sweden)

    Timothy Clark

    2015-12-01

    Full Text Available Systems in which movements occur on two significantly different time domains, such as organic electronic components with flexible molecules, require different simulation techniques for the two time scales. In the case of molecular electronics, charge transport is complicated by the several different mechanisms (and theoretical models that apply in different cases. We cannot yet combine time scales of molecular and electronic movement in simulations of real systems. This review describes our progress towards this goal.

  7. GWSCREEN: A Semi-analytical Model for Assessment of the Groundwater Pathway from Surface or Buried Contamination, Theory and User's Manual, Version 2.5

    Energy Technology Data Exchange (ETDEWEB)

    Rood, Arthur South

    1998-08-01

    GWSCREEN was developed for assessment of the groundwater pathway from leaching of radioactive and non-radioactive substances from surface or buried sources. The code was designed for implementation in the Track I and Track II assessment of Comprehensive Environmental Response, Compensation, and Liability Act sites identified as low probability hazard at the Idaho National Engineering Laboratory. The code calculates 1) the limiting soil concentration such that, after leaching and transport to the aquifer regulatory contaminant levels in groundwater are not exceeded, 2) peak aquifer concentration and associated human health impacts, and 3) aquifer concentrations and associated human health impacts as a function of time and space. The code uses a mass conservation approach to model three processes: contaminant release from a source volume, vertical contaminant transport in the unsaturated zone, and 2D or 3D contaminant transport in the saturated zone. The source model considers the sorptive properties and solubility of the contaminant. In Version 2.5, transport in the unsaturated zone is described by a plug flow or dispersive solution model. Transport in the saturated zone is calculated with a semi-analytical solution to the advection dispersion equation in groundwater. Three source models are included; leaching from a surface or buried source, infiltration pond, or user-defined arbitrary release. Dispersion in the aquifer may be described by fixed dispersivity values or three, spatial-variable dispersivity functions. Version 2.5 also includes a Monte Carlo sampling routine for uncertainty/sensitivity analysis and a preprocessor to allow multiple input files and multiple contaminants to be run in a single simulation. GWSCREEN has been validated against other codes using similar algorithms and techniques. The code was originally designed for assessment and screening of the groundwater pathway when field data are limited. It was intended to simulate relatively simple

  8. Mobility of radioactive colloidal particles in groundwater

    International Nuclear Information System (INIS)

    Nuttall, H.E.; Long, R.L.

    1993-01-01

    Radiocolloids are a major factor in the rapid migration of radioactive waste in groundwater. For at least two Los Alamos National Laboratory (LANL) sites, researchers have shown that groundwater colloidal particles were responsible for the rapid transport of radioactive waste material in groundwater. On an international scale, a review of reported field observations, laboratory column studies, and carefully collected field samples provides compelling evidence that colloidal particles enhance both radioactive and toxic waste migration. The objective of this project is to understand and predict colloid-contaminant migration through fundamental mathematical models, water sampling, and laboratory experiments and use this information to develop an effective and scientifically based colloid immobilization strategy. The article focuses on solving the suspected radiocolloid transport problems at LANL's Mortandad Canyon site. (author) 6 figs., 5 tabs., 18 refs

  9. Open-loop groundwater heat pumps development for large buildings. A case study

    Energy Technology Data Exchange (ETDEWEB)

    Lo Russo, Stefano; Civita, Massimo Vincenzo [Politecnico di Torino, Dipartimento di Ingegneria del Territorio, dell' Ambiente e delle Geotecnologie (DITAG), Corso Duca degli Abruzzi, 24 - 10129 Torino (Italy)

    2009-09-15

    A study of the feasibility of providing the heating and cooling needs of the new, large commercial building near Turin, Italy, by means of an open-loop indirect groundwater heat pump (GWHP) system is described. A finite element subsurface flow and transport simulator (FEFLOW) was used to investigate possible configurations of extraction and injection wells for five different scenarios. Modelling results confirmed the hydrogeological capacity of the site to provide the necessary amount of groundwater and associated energy with limited environmental impact. Injection of warmer (or cooler) water in the aquifer creates a thermal plume whose dimensions and geometry depend on the properties of the subsurface formations, particularly their thermal dispersivity values. The study suggests that there are several possible well configurations that could support the GWHP system without adversely affecting the aquifer. (author)

  10. Macrofilament simulation of high current beam transport

    International Nuclear Information System (INIS)

    Hayden, R.J.; Jakobson, M.J.

    1985-01-01

    Macrofilament simulation of high current beam transport through a series of solenoids has been used to investigate the sensitivity of such calculations to the initial beam distribution and to the number of filaments used in the simulation. The transport line was tuned to approximately 105 0 phase advance per cell at zero current with a tune depression of 65 0 due to the space charge. Input distributions with the filaments randomly uniform throughout a four dimensional ellipsoid and K-V input distributions have been studied. The behavior of the emittance is similar to that published for quadrupoles with like tune depression. The emittance demonstrated little growth in the first twelve solenoids, a rapid rate of growth for the next twenty, and a subsequent slow rate of growth. A few hundred filaments were sufficient to show the character of the instability. The number of filaments utilized is an order of magnitude fewer than has been utilized previously for similar instabilities. The previously published curves for simulations with less than a thousand particles show a rather constant emittance growth. If the solenoid transport line magnetic field is increased a few percent, emittance growth curves are obtained not unlike those curves. Collision growth effects are less important than indicated in the previously published results for quadrupoles

  11. Numerical simulation of the environmental impact of hydraulic fracturing of tight/shale gas reservoirs on near-surface groundwater: Background, base cases, shallow reservoirs, short-term gas, and water transport

    Science.gov (United States)

    Reagan, Matthew T; Moridis, George J; Keen, Noel D; Johnson, Jeffrey N

    2015-01-01

    Hydrocarbon production from unconventional resources and the use of reservoir stimulation techniques, such as hydraulic fracturing, has grown explosively over the last decade. However, concerns have arisen that reservoir stimulation creates significant environmental threats through the creation of permeable pathways connecting the stimulated reservoir with shallower freshwater aquifers, thus resulting in the contamination of potable groundwater by escaping hydrocarbons or other reservoir fluids. This study investigates, by numerical simulation, gas and water transport between a shallow tight-gas reservoir and a shallower overlying freshwater aquifer following hydraulic fracturing operations, if such a connecting pathway has been created. We focus on two general failure scenarios: (1) communication between the reservoir and aquifer via a connecting fracture or fault and (2) communication via a deteriorated, preexisting nearby well. We conclude that the key factors driving short-term transport of gas include high permeability for the connecting pathway and the overall volume of the connecting feature. Production from the reservoir is likely to mitigate release through reduction of available free gas and lowering of reservoir pressure, and not producing may increase the potential for release. We also find that hydrostatic tight-gas reservoirs are unlikely to act as a continuing source of migrating gas, as gas contained within the newly formed hydraulic fracture is the primary source for potential contamination. Such incidents of gas escape are likely to be limited in duration and scope for hydrostatic reservoirs. Reliable field and laboratory data must be acquired to constrain the factors and determine the likelihood of these outcomes. Key Points: Short-term leakage fractured reservoirs requires high-permeability pathways Production strategy affects the likelihood and magnitude of gas release Gas release is likely short-term, without additional driving forces PMID

  12. In Situ Monitoring of Groundwater Contamination Using the Kalman Filter For Sustainable Remediation

    Science.gov (United States)

    Schmidt, F.; Wainwright, H. M.; Faybishenko, B.; Denham, M. E.; Eddy-Dilek, C. A.

    2017-12-01

    Sustainable remediation - based on less intensive passive remediation and natural attenuation - has become a desirable remediation alternative at contaminated sites. Although it has a number of benefits, such as reduced waste and water/energy usage, it carries a significant burden of proof to verify plume stability and to ensure insignificant increase of risk to public health. Modeling of contaminant transport is still challenging despite recent advances in numerical methods. Long-term monitoring has, therefore, become a critical component in sustainable remediation. However, the current approach, which relies on sparse groundwater sampling, is problematic, since it could miss sudden significant changes in plume behavior. A new method is needed to combine existing knowledge about contaminant behavior and latest advances in in situ groundwater sensors. This study presents an example of the effective use of the Kalman filter approach to estimate contaminant concentrations, based on in situ measured water quality parameters (e.g. electrical conductivity and pH) along with the results of sparse groundwater sampling. The Kalman filter can effectively couple physical models and data correlations between the contaminant concentrations and in situ measured variables. We aim (1) to develop a framework capable of integrating different data types to provide accurate contaminant concentration estimates, (2) to demonstrate that these results remain reliable, even when the groundwater sampling frequency is reduced, and (3) to evaluate the future efficacy of this strategy using reactive transport simulations. This framework can also serve as an early warning system for detecting unexpected plume migration. We demonstrate our approach using historical and current groundwater data from the Savannah River Site (SRS) F-Area Seepage Basins to estimate uranium and tritium concentrations. The results show that the developed method can provide reliable estimates of contaminant

  13. Numerical simulation of ground-water flow through glacial deposits and crystalline bedrock in the Mirror Lake area, Grafton County, New Hampshire

    Science.gov (United States)

    Tiedeman, Claire; Goode, Daniel J.; Hsieh, Paul A.

    1997-01-01

    This report documents the development of a computer model to simulate steady-state (long-term average) flow of ground water in the vicinity of Mirror Lake, which lies at the eastern end of the Hubbard Brook valley in central New Hampshire. The 10-km2 study area includes Mirror Lake, the three streams that flow into Mirror Lake, Leeman's Brook, Paradise Brook, and parts of Hubbard Brook and the Pemigewasset River. The topography of the area is characterized by steep hillsides and relatively flat valleys. Major hydrogeologic units include glacial deposits, composed of till containing pockets of sand and gravel, and fractured crystalline bedrock, composed of schist intruded by granite, pegmatite, and lamprophyre. Ground water occurs in both the glacial deposits and bedrock. Precipitation and snowmelt infiltrate to the water table on the hillsides, flow downslope through the saturated glacial deposits and fractured bedrock, and discharge to streams and to Mirror Lake. The model domain includes the glacial deposits, the uppermost 150m of bedrock, Mirror Lake, the layer of organic sediments on the lake bottom, and streams and rivers within the study area. A streamflow routing package was included in the model to simulate baseflow in streams and interaction between streams and ground water. Recharge from precipitation is assumed to be areally uniform, and riparian evapotranspiration along stream banks is assumed negligible. The spatial distribution of hydraulic conductivity is represented by dividing the model domain into several zones, each having uniform hydraulic properties. Local variations in recharge and hydraulic conductivities are ignored; therefore, the simulation results characterize the general ground-water system, not local details of ground-water movement. The model was calibrated using a nonlinear regression method to match hydraulic heads measured in piezometers and wells, and baseflow in three inlet streams to Mirror Lake. Model calibration indicates that

  14. Improving AVSWAT Stream Flow Simulation by Incorporating Groundwater Recharge Prediction in the Upstream Lesti Watershed, East Java, Indonesia

    Directory of Open Access Journals (Sweden)

    Christina Rahayuningtyas

    2014-01-01

    Full Text Available The upstream Lesti watershed is one of the major watersheds of East Java in Indonesia, covering about 38093 hectares. Although there are enough water resources to meet current demands in the basin, many challenges including high spatial and temporal variability in precipitation from year to year exist. It is essential to understand how the climatic condition affects Lesti River stream flow in each sub basin. This study investigated the applicability of using the Soil and Water Assessment Tool (SWAT with the incorporation of groundwater recharge prediction in stream flow simulation in the upstream Lesti watershed. Four observation wells in the upstream Lesti watershed were used to evaluate the seasonal and annual variations in the water level and estimate the groundwater recharge in the deep aquifer. The results show that annual water level rise was within the 2800 - 5700 mm range in 2007, 3900 - 4700 mm in 2008, 3200 - 5100 mm in 2009, and 2800 - 4600 mm in 2010. Based on the specific yield and the measured water level rise, the area-weighted groundwater predictions at the watershed outlet are 736, 820.9, 786.7, 306.4 mm in 2007, 2008, 2009, and 2010, respectively. The consistency test reveals that the R-square statistical value is greater than 0.7, and the DV (% ranged from 32 - 55.3% in 2007 - 2010. Overall, the SWAT model performs better in the wet season flow simulation than the dry season. It is suggested that the SWAT model needs to be improved for stream flow simulation in tropical regions.

  15. Geochemical modelling baseline compositions of groundwater

    DEFF Research Database (Denmark)

    Postma, Diederik Jan; Kjøller, Claus; Andersen, Martin Søgaard

    2008-01-01

    and variations in water chemistry that are caused by large scale geochemical processes taking place at the timescale of thousands of years. The most important geochemical processes are ion exchange (Valreas and Aveiro) where freshwater solutes are displacing marine ions from the sediment surface, and carbonate......Reactive transport models, were developed to explore the evolution in groundwater chemistry along the flow path in three aquifers; the Triassic East Midland aquifer (UK), the Miocene aquifer at Valreas (F) and the Cretaceous aquifer near Aveiro (P). All three aquifers contain very old groundwaters...... dissolution (East Midlands, Valreas and Aveiro). Reactive transport models, employing the code PHREEQC, which included these geochemical processes and one-dimensional solute transport were able to duplicate the observed patterns in water quality. These models may provide a quantitative understanding...

  16. Experimental and numerical investigations of soil water balance at the hinterland of the Badain Jaran Desert for groundwater recharge estimation

    Science.gov (United States)

    Hou, Lizhu; Wang, Xu-Sheng; Hu, Bill X.; Shang, Jie; Wan, Li

    2016-09-01

    Quantification of groundwater recharge from precipitation in the huge sand dunes is an issue in accounting for regional water balance in the Badain Jaran Desert (BJD) where about 100 lakes exist between dunes. In this study, field observations were conducted on a sand dune near a large saline lake in the BJD to investigate soil water movement through a thick vadose zone for groundwater estimation. The hydraulic properties of the soils at the site were determined using in situ experiments and laboratory measurements. A HYDRUS-1D model was built up for simulating the coupling processes of vertical water-vapor movement and heat transport in the desert soil. The model was well calibrated and validated using the site measurements of the soil water and temperature at various depths. Then, the model was applied to simulate the vertical flow across a 3-m-depth soil during a 53-year period under variable climate conditions. The simulated flow rate at the depth is an approximate estimation of groundwater recharge from the precipitation in the desert. It was found that the annual groundwater recharge would be 11-30 mm during 1983-2012, while the annual precipitation varied from 68 to 172 mm in the same period. The recharge rates are significantly higher than those estimated from the previous studies using chemical information. The modeling results highlight the role of the local precipitation as an essential source of groundwater in the BJD.

  17. Determination of Groundwater Velocity and Dispersion Parameters by Borehole Wall Multielectrode Geoelectrics

    Science.gov (United States)

    Kessels, W.; Wuttke, M. W.

    2007-05-01

    measurements and vertical four point electrode interpretations. The transport equation for NaCl-tracered water is the basic rule to determine the groundwater transport velocity. Numerical calculations to simulate the measurement are carried out with the program FEFLOW. Due to the density contrast, the tracer undergoes vertical movement. Kessels, W., Zoth, G.(1998): Doppelmantel - Packer mit geoelektrischer Meßtechnik zur Bestimmung der Abstandsgeschwindigkeit des Grundwassers, Patent Az:19855048.0, GGA-Institut, Germany, Hannover. KESSELS, W., RIFAI, H., THORENZ, C., ZOTH, G.(2002): Multi Electrode Geoelectric on the Borehole Wall- Determination of groundwater velocity and dispersion parameters, AGU spring meeting, Washington KESSELS, W., ZOTH, G., WONIK, T., FULDA, C. (1999): THE USE OF SALT CARTRIDGES FOR FLUID LOGGING. XXIV GENERAL ASSEMBLY OF E.G.S. THE HAGUE, THE NETHERLANDS PANTELEIT,B., KESSELS, W., BINOT, F (2006): MUD TRACER TEST DURING SOFT ROCK DRILLING; W.R.R., VOL. 42, W11415, DOI:10.1029/2005WR004487

  18. Simulation of groundwater flows in unsaturated porous media

    International Nuclear Information System (INIS)

    Musy, A.

    1976-01-01

    Groundwater flow in unsaturated porous media is caused by a potential gradient where the total potential consists of the sum of a gravitational and a suction component. The partial differential equations which result from the general analysis of groundwater flow in unsaturated soil are solved by succesive approximations with the finite-element method. General boundary and initial conditions, linear or curvilinear shaped elements (isoparametric elements) and steady-state or transient flow can be introduced into the numerical computer program. The results of this mathematical model are compared with experimental data established in the laboratory with a physical groundwater model. This is a rectangular testing tank of dimension 3 x 1.5 x 0.15 m and contains a silty clay loam. The variation of the bulk density and the volumetric moisture of the soil as a function of time and space are measured by gamma absorption from a 137 Cs source with 300 mCi intensity

  19. Water Balance Study of a Groundwater-dependent Oak Forest

    Directory of Open Access Journals (Sweden)

    MÓRICZ, Norbert

    2010-01-01

    Full Text Available The objectives of this study were (1 to estimate the water balance components of an oak standby calibrating a Hydrus 1-D model, (2 to determine the groundwater consumption by the water tablefluctuation method and (3 to compare the results of the modelling with a remote-sensing based estimation.Model simulation described the observed soil moisture and groundwater level relatively well, theroot mean square errors varied between 12.0 and 14.9% for the soil moisture measurements and 5.0%for the groundwater level. Groundwater consumption was estimated also by the water table fluctuationmethod, which provided slightly different groundwater consumption rates than estimated by theHydrus model simulation. The simulated evapotranspiration was compared with results of a remotesensingbased estimation using the surface temperature database of MODIS.According to the Hydrus model, the estimated evapotranspiration resulted from transpiration(73%, interception loss (23% and soil surface evaporation (4% in the two-year study period. Theproportion of groundwater consumption was 58% of the total transpiration. During the dry growingseason of 2007 the groundwater consumption was significant with 66% of the total transpiration.Water supply from groundwater was found to be less important in the wet growing season of 2008with 50%. The remote-sensing based estimation of evapotranspiration was about 4% lower than themodel based results of nearby comparable sites.

  20. Multi-objective optimization of in-situ bioremediation of groundwater using a hybrid metaheuristic technique based on differential evolution, genetic algorithms and simulated annealing

    Directory of Open Access Journals (Sweden)

    Kumar Deepak

    2015-12-01

    Full Text Available Groundwater contamination due to leakage of gasoline is one of the several causes which affect the groundwater environment by polluting it. In the past few years, In-situ bioremediation has attracted researchers because of its ability to remediate the contaminant at its site with low cost of remediation. This paper proposed the use of a new hybrid algorithm to optimize a multi-objective function which includes the cost of remediation as the first objective and residual contaminant at the end of the remediation period as the second objective. The hybrid algorithm was formed by combining the methods of Differential Evolution, Genetic Algorithms and Simulated Annealing. Support Vector Machines (SVM was used as a virtual simulator for biodegradation of contaminants in the groundwater flow. The results obtained from the hybrid algorithm were compared with Differential Evolution (DE, Non Dominated Sorting Genetic Algorithm (NSGA II and Simulated Annealing (SA. It was found that the proposed hybrid algorithm was capable of providing the best solution. Fuzzy logic was used to find the best compromising solution and finally a pumping rate strategy for groundwater remediation was presented for the best compromising solution. The results show that the cost incurred for the best compromising solution is intermediate between the highest and lowest cost incurred for other non-dominated solutions.

  1. Numerical evaluation and optimization of depth-oriented temperature measurements for the investigation of thermal influences on groundwater

    Science.gov (United States)

    Köhler, Mandy; Haendel, Falk; Epting, Jannis; Binder, Martin; Müller, Matthias; Huggenberger, Peter; Liedl, Rudolf

    2015-04-01

    , where the mean thickness of the unsaturated zone amounts to 19 m, it could be observed that atmospheric seasonal temperature variations are small compared to advective groundwater heat transport. At chosen locations: i) near the river Rhine to study river-groundwater interaction processes, ii) downstream of a thermal groundwater user who uses water for cooling and infiltrates water with elevated temperatures and iii) downstream of a building structure reaching into the groundwater saturated zone, models were further extended to study selected thermal processes in detail and to investigate if these models can reproduce thermal impacts in the vicinity of the temperature measurement devices. Calibration, based on the depth-oriented temperature measurements, was performed for the saturated and unsaturated zone, respectively. Model results show that, although depth-oriented measurements provide valuable insights into local thermal processes, the identification of the governing impacts is strongly dependent on an appropriate positioning of the measurement device. Numerical simulations based on existing flow- and heat transport models, considering the site specific local hydraulic and thermal boundary conditions, allow optimizing the location of such systems before installation. Furthermore, the results of the local heat transport models can be transferred to regional scale models which are an important tool for thermal management in urban areas.

  2. The effects of withdrawals and drought on groundwater availability in the Northern Guam Lens Aquifer, Guam

    Science.gov (United States)

    Gingerich, Stephen B.

    2013-01-01

    Owing to population growth, freshwater demand on Guam has increased in the past and will likely increase in the future. During the early 1970s to 2010, groundwater withdrawals from the limestone Northern Guam Lens Aquifer, the main source of freshwater on the island, tripled from about 15 to 45 million gallons per day. Because of proposed military relocation to Guam and expected population growth, freshwater demand on Guam is projected to increase further. The expected increased demand for groundwater has led to concern over the long-term sustainability of withdrawals from existing and proposed wells. A three-dimensional numerical groundwater flow and transport model was developed to simulate the effects of hypothetical withdrawal and recharge scenarios on water levels and on the transition zone between freshwater and saltwater. The model was constructed by using average recharge during 1961–2005 and withdrawals from 2010. Hydraulic properties used to construct the model were initially based on published estimates but ultimately were adjusted to obtain better agreement between simulated and measured water levels and salinity profiles in the modeled area. Two hypothetical groundwater withdrawal scenarios were simulated: no withdrawal to simulate predevelopment conditions and withdrawal at 2010 rates under a 5-year drought. Simulation results indicate that prior to pumping; the fresh-water lens was 10 to 50 feet thicker in the Yigo-Tumon basin and more than 50 feet thicker in the Hagåtña basin. Results also indicate that continuing the 2010 withdrawal distribution during a 5-year drought would result in decreased water levels, a thinner freshwater lens, and increased salinity of water pumped from wells. The available water with an acceptable salinity (chloride concentration less than 200 milligrams per liter) would decrease from about 34 million gallons per day to 11.5 million gallons per day after 5 years but recover to pre-drought levels 5 years after the

  3. Vadose zone transport field study: Detailed test plan for simulated leak tests

    International Nuclear Information System (INIS)

    AL Ward; GW Gee

    2000-01-01

    The US Department of Energy (DOE) Groundwater/Vadose Zone Integration Project Science and Technology initiative was created in FY 1999 to reduce the uncertainty associated with vadose zone transport processes beneath waste sites at DOE's Hanford Site near Richland, Washington. This information is needed not only to evaluate the risks from transport, but also to support the adoption of measures for minimizing impacts to the groundwater and surrounding environment. The principal uncertainties in vadose zone transport are the current distribution of source contaminants and the natural heterogeneity of the soil in which the contaminants reside. Oversimplified conceptual models resulting from these uncertainties and limited use of hydrologic characterization and monitoring technologies have hampered the understanding contaminant migration through Hanford's vadose zone. Essential prerequisites for reducing vadose transport uncertainly include the development of accurate conceptual models and the development or adoption of monitoring techniques capable of delineating the current distributions of source contaminants and characterizing natural site heterogeneity. The Vadose Zone Transport Field Study (VZTFS) was conceived as part of the initiative to address the major uncertainties confronting vadose zone fate and transport predictions at the Hanford Site and to overcome the limitations of previous characterization attempts. Pacific Northwest National Laboratory (PNNL) is managing the VZTFS for DOE. The VZTFS will conduct field investigations that will improve the understanding of field-scale transport and lead to the development or identification of efficient and cost-effective characterization methods. Ideally, these methods will capture the extent of contaminant plumes using existing infrastructure (i.e., more than 1,300 steel-cased boreholes). The objectives of the VZTFS are to conduct controlled transport experiments at well-instrumented field sites at Hanford to

  4. Groundwater fluoride contamination: A reappraisal

    Directory of Open Access Journals (Sweden)

    Amlan Banerjee

    2015-03-01

    Full Text Available Dissolution of fluorite (CaF2 and/or fluorapatite (FAP [Ca5(PO43F], pulled by calcite precipitation, is thought to be the dominant mechanism responsible for groundwater fluoride (F− contamination. Here, one dimensional reactive–transport models are developed to test this mechanism using the published dissolution and precipitation rate kinetics for the mineral pair FAP and calcite. Simulation results correctly show positive correlation between the aqueous concentrations of F− and CO32− and negative correlation between F− and Ca2+. Results also show that precipitation of calcite, contrary to the present understanding, slows down the FAP dissolution by 106 orders of magnitude compared to the FAP dissolution by hydrolysis. For appreciable amount of fluoride contamination rock–water interaction time must be long and of order 106 years.

  5. A high resolution global scale groundwater model

    Science.gov (United States)

    de Graaf, Inge; Sutanudjaja, Edwin; van Beek, Rens; Bierkens, Marc

    2014-05-01

    As the world's largest accessible source of freshwater, groundwater plays a vital role in satisfying the basic needs of human society. It serves as a primary source of drinking water and supplies water for agricultural and industrial activities. During times of drought, groundwater storage provides a large natural buffer against water shortage and sustains flows to rivers and wetlands, supporting ecosystem habitats and biodiversity. Yet, the current generation of global scale hydrological models (GHMs) do not include a groundwater flow component, although it is a crucial part of the hydrological cycle. Thus, a realistic physical representation of the groundwater system that allows for the simulation of groundwater head dynamics and lateral flows is essential for GHMs that increasingly run at finer resolution. In this study we present a global groundwater model with a resolution of 5 arc-minutes (approximately 10 km at the equator) using MODFLOW (McDonald and Harbaugh, 1988). With this global groundwater model we eventually intend to simulate the changes in the groundwater system over time that result from variations in recharge and abstraction. Aquifer schematization and properties of this groundwater model were developed from available global lithological maps and datasets (Dürr et al., 2005; Gleeson et al., 2010; Hartmann and Moosdorf, 2013), combined with our estimate of aquifer thickness for sedimentary basins. We forced the groundwater model with the output from the global hydrological model PCR-GLOBWB (van Beek et al., 2011), specifically the net groundwater recharge and average surface water levels derived from routed channel discharge. For the parameterization, we relied entirely on available global datasets and did not calibrate the model so that it can equally be expanded to data poor environments. Based on our sensitivity analysis, in which we run the model with various hydrogeological parameter settings, we observed that most variance in groundwater

  6. Kinetic simulations of neoclassical and anomalous transport processes in helical systems

    International Nuclear Information System (INIS)

    Sugama, Hideo; Watanabe, Tomohiko; Nunami, Masanori; Satake, Shinsuke; Matsuoka, Seikichi; Tanaka, Kenji

    2012-01-01

    Drift kinetic and gyrokinetic theories and simulations are powerful means for quantitative predictions of neoclassical and anomalous transport fluxes in helical systems such as the Large Helical Device (LHD). The δf Monte Carlo particle simulation code, FORTEC-3D, is used to predict radial profiles of the neoclassical particle and heat transport fluxes and the radial electric field in helical systems. The radial electric field profiles in the LHD plasmas are calculated from the ambipolarity condition for the neoclassical particle fluxes obtained by the global simulations using the FORTEC-3D code, in which effects of ion or electron finite orbit widths are included. Gyrokinetic Vlasov simulations using the GKV code verify the theoretical prediction that the neoclassical optimization of helical magnetic configuration enhances the zonal flow generation which leads to the reduction of the turbulent heat diffusivity χ i due to the ion temperature gradient (ITG) turbulence. Comparisons between results for the high ion temperature LHD experiment and the gyrokinetic simulations using the GKV-X code show that the χ i profile and the poloidal wave number spectrum of the density fluctuation obtained from the simulations are in reasonable agreements with the experimental results. It is predicted theoretically and confirmed by the linear GKV simulations that the E × B rotation due to the background radial electric field E r can enhance the zonal-flow response to a given source. Thus, in helical systems, the turbulent transport is linked to the neoclassical transport through E r which is determined from the ambipolar condition for neoclassical particle fluxes and influences the zonal flow generation leading to reduction of the turbulent transport. In order to investigate the E r effect on the regulation of the turbulent transport by the zonal flow generation, the flux-tube bundle model is proposed as a new method for multiscale gyrokinetic simulations. (author)

  7. The use of surrogates for an optimal management of coupled groundwater-agriculture hydrosystems

    Science.gov (United States)

    Grundmann, J.; Schütze, N.; Brettschneider, M.; Schmitz, G. H.; Lennartz, F.

    2012-04-01

    For ensuring an optimal sustainable water resources management in arid coastal environments, we develop a new simulation based integrated water management system. It aims at achieving best possible solutions for groundwater withdrawals for agricultural and municipal water use including saline water management together with a substantial increase of the water use efficiency in irrigated agriculture. To achieve a robust and fast operation of the management system regarding water quality and water quantity we develop appropriate surrogate models by combining physically based process modelling with methods of artificial intelligence. Thereby we use an artificial neural network for modelling the aquifer response, inclusive the seawater interface, which was trained on a scenario database generated by a numerical density depended groundwater flow model. For simulating the behaviour of high productive agricultural farms crop water production functions are generated by means of soil-vegetation-atmosphere-transport (SVAT)-models, adapted to the regional climate conditions, and a novel evolutionary optimisation algorithm for optimal irrigation scheduling and control. We apply both surrogates exemplarily within a simulation based optimisation environment using the characteristics of the south Batinah region in the Sultanate of Oman which is affected by saltwater intrusion into the coastal aquifer due to excessive groundwater withdrawal for irrigated agriculture. We demonstrate the effectiveness of our methodology for the evaluation and optimisation of different irrigation practices, cropping pattern and resulting abstraction scenarios. Due to contradicting objectives like profit-oriented agriculture vs. aquifer sustainability a multi-criterial optimisation is performed.

  8. Conceptual and numerical models of groundwater flow and solute transport in fracture zones: Application to the Aspo Island (Sweden); Modelos conceptuales y numericos de flujo y transporte de solutos en zonas de fractura: aplicacion a la isla de Aspo (Suecia)

    Energy Technology Data Exchange (ETDEWEB)

    Molinero, J.; Samper, J.

    2003-07-01

    Several countries around the world are considering the final disposal of high-level radioactive waste in deep repositories located in fractured granite formations. Evaluating the long term safety of such repositories requires sound conceptual and numerical models which must consider simultaneously groundwater flow, solute transport and chemical and radiological processes. These models are being developed from data and knowledge gained from in situ experiments carried out at deep underground laboratories such as that of Aspo, Sweden, constructed in fractured granite. The Redox Zone Experiment is one of such experiments performed at Aspo in order to evaluate the effects of the construction of the access tunnel on the hydrogeological and hydrochemical conditions of a fracture zone intersected by the tunnel. Previous authors interpreted hydrochemical and isotopic data of this experiment using a mass-balance approach based on a qualitative description of groundwater flow conditions. Such an interpretation, however, is subject to uncertainties related to an over-simplified conceptualization of groundwater flow. Here we present numerical models of groundwater flow and solute transport for this fracture zone. The first model is based on previously published conceptual model. It presents noticeable un consistencies and fails to match simultaneously observed draw downs and chloride breakthrough curves. To overcome its limitations, a revised flow and transport model is presented which relies directly on available hydrodynamic and transport parameters, is based on the identification of appropriate flow and transport boundary conditions and uses, when needed, solute data extrapolated from nearby fracture zones. A significant quantitative improvement is achieved with the revised model because its results match simultaneously drawdown and chloride data. Other improvements are qualitative and include: ensuring consistency of hydrodynamic and hydrochemical data and avoiding

  9. Reactive transport modeling of coupled inorganic and organic processes in groundwater

    Energy Technology Data Exchange (ETDEWEB)

    Brun, Adam

    1997-12-31

    The main goals of this project are to develop and apply a reactive transport code for simulation of coupled organic and inorganic processes in the pollution plume in the ground water down-gradient from the Vejen landfill, Denmark. The detailed field investigations in this aquifer have previously revealed a complex pattern of strongly interdependent organic and inorganic processes. These processes occur simultaneously in a flow and transport system where the mixing of reactive species is influenced by the rather complex geology in the vicinity of the landfill. The removal of organic matter is influenced by the presence of various electron acceptors that also are involved in various inorganic geochemical reactions. It was concluded from the investigations that degradation of organic matter, complexation, mineral precipitation and dissolution, ion-exchange and inorganic redox reactions, as a minimum, should be included in the formulation of the model. The coupling of the organic and inorganic processes is developed based on a literature study. All inorganic processes are as an approximation described as equilibriumm processes. The organic processes are described by a maximum degradation rate that is decreased according to the availability of the participants in the processes, the actual pH, and the presence of inhibiting species. The reactive transport code consists of three separate codes, a flow and transport code, a geochemical code, and a biodegradation code. An iterative solution scheme couples the three codes. The coupled code was successfully verified for simple problems for which analytical solutions exist. For more complex problems the code was tested on synthetic cases and expected plume behavior was successfully simulated. Application of the code to the Vejen landfill aquifer was successful to the degree that the redox zonation down-gradient from the landfill was simulated correctly and that several of the simulated plumes showed a reasonable agreement with

  10. Determinants of Shallow Groundwater As Variability in Bangladesh

    Science.gov (United States)

    Radloff, K. A.; Zheng, Y.; Stute, M.; Rahman, M.; Mihajlov, I.; Siu, H.; Huq, M.; Choudhury, I.; Ahmed, K.; van Geen, A.

    2010-12-01

    Manually operated tube wells that tap into shallow aquifers remain a critical source of untreated drinking water in south Asia and an estimated 37 million people are still exposed to elevated levels of As in Bangladesh(1). This field effort sought to address two questions. What mechanisms control the partitioning of As between groundwater and sediment? How does groundwater transport affect the spatial variability of dissolved As? Understanding the source of groundwater variability is essential for understanding how [As] will change with time, especially as Bangladesh and its water demands develop. Arsenic mobility and transport within the shallow aquifer was investigated at a 0.5 km2 site where [As] increases from conditions measured by spiking freshly collected sediment was remarkably uniform: Kd = 1.5 ± 0.5 L/kg, at 14 of 15 locations. Push- pull tests were used to alter groundwater [As] surrounding a well, without disturbing the sediment. The aquifer responded to the imposed dis-equilibrium by either adsorbing or desorbing As within a few days. These results provide further evidence that groundwater [As] is controlled by As sorption reactions with the sediment that reach equilibrium rapidly compared to the time scale of groundwater flow. A simple reactive-transport model for the site based on the measured partitioning coefficient, Kd, however, supports the notion that the [As] gradient observed reflects the gradual removal of As by groundwater flow over hundreds to thousands of years. The onset of irrigation and industrial pumping at this site has induced a reversal in flow, consequently groundwater now moves from high [As] into low [As] areas. This change could result in rising [As] to levels >50 μg/L in the village within the next few decades. The rapid economic development of Bangladesh could induce similar changes in groundwater flow, and thus As concentrations, elsewhere. This suggests that periodic monitoring of shallow wells low in As within regions of

  11. Mass Transfer Behavior of Perfluorinated Chemicals in Saturated Clay-rich Sands: A Laboratory-based Study on Fate and Transport in Groundwater and Sediments

    Science.gov (United States)

    Greenberg, R. R.; Tick, G. R.; Abbott, J. B., III; Carroll, K. C.

    2017-12-01

    Perfluoroalkyl substances (PFAS) are a class of emerging contaminants that pose a threat to the human health and the quality of groundwater, surface water, and drinking water supplies. This study aims to elucidate the primary physicochemical factors controlling the fate and transport of the PFAS contaminants, perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS), in groundwater. Physicochemical processes of intercalation, adsorption, and desorption were investigated for the retention of PFAS at different initial aqueous-phase concentrations in modified-natural sediments composed of sand (40/50 accusand; foc = 0.04% unmodified) with low, medium, and high organic carbon contents (foc = 10, 20, and 50%) and various pre-conditioned clay-fractions. Diffusional mass-transfer limitations were evaluated based on initial PFAS concentration, specific clay structure, and resulting contaminant intercalation (d-spacing changes). A series of short- (48 hr), medium- (7 day) and long-term (30 day) batch and column experiments were conducted to determine physicochemical processes as a function of compound chemistry, sediment geochemistry, sorbent crystalline structure, and contaminant/sediment contact-time. Physicochemical parameters, PFAS concentrations, and sediment characterization were conducted using high performance liquid chromatography (HPLC), X-ray diffraction (XRD), and furnace combustion analytical techniques. The results of PFAS contaminant transport, under the different conditions tested, provide a scientific contribution with application to the development of improved risk assessments, predictions of fate and transport, and more effective remediation strategies for emerging perfluorinated contaminants in soil and groundwater.

  12. Modeling multi-component transport and enhanced anaerobic dechlorination processes in a single fracture-clay matrix system

    DEFF Research Database (Denmark)

    Chambon, Julie Claire Claudia; Broholm, Mette Martina; Binning, Philip John

    2010-01-01

    Clayey tills contaminated with chlorinated solvents are a threat to groundwater and are difficult to remediate. A numerical model is developed for assessing leaching processes and for simulating the remediation via enhanced anaerobic dechlorination. The model simulates the transport...... to the physical processes, mainly diffusion in the matrix, than to the biogeochemical processes, when dechlorination is assumed to take place in a limited reaction zone only. The inclusion of sequential dechlorination in clay fracture transport models is crucial, as the contaminant flux to the aquifer...

  13. Seasonal variation of residence time in spring and groundwater evaluated by CFCs and numerical simulation in mountainous headwater catchment

    Science.gov (United States)

    Tsujimura, Maki; Watanabe, Yasuto; Ikeda, Koichi; Yano, Shinjiro; Abe, Yutaka

    2016-04-01

    Headwater catchments in mountainous region are the most important recharge area for surface and subsurface waters, additionally time information of the water is principal to understand hydrological processes in the catchments. However, there have been few researches to evaluate variation of residence time of subsurface water in time and space at the mountainous headwaters especially with steep slope. We investigated the temporal variation of the residence time of the spring and groundwater with tracing of hydrological flow processes in mountainous catchments underlain by granite, Yamanashi Prefecture, central Japan. We conducted intensive hydrological monitoring and water sampling of spring, stream and ground waters in high-flow and low-flow seasons from 2008 through 2013 in River Jingu Watershed underlain by granite, with an area of approximately 15 km2 and elevation ranging from 950 m to 2000 m. The CFCs, stable isotopic ratios of oxygen-18 and deuterium, inorganic solute constituent concentrations were determined on all water samples. Also, a numerical simulation was conducted to reproduce of the average residence times of the spring and groundwater. The residence time of the spring water estimated by the CFCs concentration ranged from 10 years to 60 years in space within the watershed, and it was higher (older) during the low flow season and lower (younger) during the high flow season. We tried to reproduce the seasonal change of the residence time in the spring water by numerical simulation, and the calculated residence time of the spring water and discharge of the stream agreed well with the observed values. The groundwater level was higher during the high flow season and the groundwater dominantly flowed through the weathered granite with higher permeability, whereas that was lower during the low flow season and that flowed dominantly through the fresh granite with lower permeability. This caused the seasonal variation of the residence time of the spring

  14. Effect of co-transporter blockers on non-synaptic epileptiform activity—computational simulation

    Science.gov (United States)

    Rodrigues Lopes, Mariana; Canton Santos, Luiz Eduardo; Márcio Rodrigues, Antônio; Antônio Duarte, Mario; Catelli Infantosi, Antonio Fernando; Alexandre Scorza, Fulvio; Arida, Ricardo Mario; Madureira, Ana Paula; Amaral da Silveira, Gilcélio; dos Santos, Ivans Carlos; Abrão Cavalheiro, Esper; Guimarães de Almeida, Antônio-Carlos

    2013-10-01

    The important role of cation-chloride co-transporters in epilepsy is being supported by an increasing number of investigations. However, enormous complexity is involved since the action of these co-transporters has effects on the ionic homeostasis influencing directly the neuronal excitability and the tissue propensity to sustain seizure. To unravel the complex mechanisms involving the co-transporters action during seizure, this paper shows simulations of non-synaptic epileptiform activity and the effect of the blockage of the two different types of cation-chloride co-transporters present in the brain: Na, K and 2Cl co-transporter (NKCC) and K and Cl co-transporter (KCC). The simulations were performed with an electrochemical model representing the non-synaptic structure of the granule cell layer of the dentate gyrus (DG) of the rat hippocampus. The simulations suggest: (i) the potassium clearance is based on the systemic interplay between the Na/K pump and the NKCC co-transporters; (ii) the simultaneous blockage of the NKCC of the neurons and KCC of glial cells acts efficiently suppressing the epileptiform activities; and (iii) the simulations show that depending on the combined blockage of the co-transporters, the epileptiform activities may be suppressed or enhanced.

  15. Numerical simulation of the anomalous transport at the plasma-edge

    International Nuclear Information System (INIS)

    Pohn, E.

    2001-03-01

    In addition to the classical transport which is caused by Coloumb-collisions two further transport mechanisms take place in an inhomogeneous magnetically confined thermonuclear fusion-plasma, the neoclassical and the anomalous transport. The anomalous transport is caused by collective motion of the plasma-particles respectively turbulence and essentially affects the energy-confinement-time of the plasma. The energy-confinement-time in turn constitutes an important criterion with respect to the feasibility of using nuclear fusion for energy production. The anomalous transport is theoretically not yet well understood. By means of numerical simulations of the anomalous transport in the plasma edge, it is the intention of this work to contribute to the understanding of this transport mechanism. The Vlasov-Poisson-system constitutes the starting point for all performed simulations. This system consists of kinetic equations, which model for each particle-species the motion of the particles composing the plasma in six-dimensional phase-space. A coupling of these kinetic equations occurs due to the Poisson-equation, resulting in a nonlinear system of differential equations. The time evolution of this system was calculated numerically. On the one hand, simulations were performed where the whole velocity-space was retained. This fully-kinetic model was applied for the spatially one- as well as two-dimensional case. In the one-dimensional case only the radial direction of the plasma-edge was modeled, i.e. the direction along which the plasma joins to the vacuum. When performing the spatially two-dimensional simulations, in addition the poloidal direction has been regarded. A second set of simulations was performed using a gyro-kinetic model. In this model only the velocity-component parallel to the magnetic field vector is retained. The components perpendicular to the magnetic field vector, which are responsible for the gyration of particles, are omitted from phase-space but

  16. Complex relationship between groundwater velocity and concentration of radioactive contaminants

    International Nuclear Information System (INIS)

    Kaszeta, F.E.; Bond, F.W.

    1980-01-01

    This paper uses the results from the Multi-component Mass Transport model to examine the complex interrelationship between groundwater velocity and contaminant dispersion, decay, and retardation with regard to their influence on the contaminant concentration distribution as it travels through the geosphere to the biosphere. The rate of transport of contaminants through the geosphere is governed by groundwater velocity, leach rate, and contaminant retardation. The dominant characteristics of the contaminant concentration distribution are inherited during leaching and modified during transport by dilution, dispersion and decay. For a hypothetical non-decaying, non-dispersing contaminant with no retardation properties, the shape of the source term distribution is governed by the groundwater velocity (dilution) and leach rate. This distribution remains unchanged throughout transport. Under actual conditions, however, dispersion, decay and retardation modify the concentration distribution during both leaching and transport. The amount of dispersion is determined by the distance traveled, but it does have a greater peak-reducing influence on spiked distributions than square-shaped distributions. Decay acts as an overall scaling factor on the concentration distribution. Retardation alters the contaminant travel time and therefore indirectly influences the amount of dilution, dispersion and decay. Simple relationships between individual parameters and groundwater velocity as they influence peak concentration do not exist. For those cases where the source term is not solubility-limited and flow past the waste is independent of regional hydrologic conditions, a threshold concentration occurs at a specific groundwater velocity where the effects of dilution balance those of dispersion and decay

  17. Hydrologic transport of radionuclides from low-level waste burial grounds

    International Nuclear Information System (INIS)

    Duguid, J.O.

    1977-01-01

    The physical characteristics of the virgin site and of the disturbed site after burial drastically affect the transport of radionuclides from buried waste. The disturbance of the land surface during the waste burial operation causes changes in the local ground-water regimen. These changes can increase the water table elevation and cause the occurrence of perched water in burial trenches. The combination of these changes may lead to submersion of the waste and to increased radionuclide transport from the burial site in both surface and ground water. Factors such as ion exchange can retard or in some cases, with competing ions, can also mobilize radionuclides and increase their discharge into ground and surface water. Because of complexing agents (organics) contained in the waste, increased mobility of some radionuclides can be expected. The chemical form of radionuclides in the water, the ground-water quality, and the chemistry of the geologic formation in which the waste is buried all influence the movement of radionuclides in the hydrologic system. For the assessment of the environmental impact of low-level waste burial, models capable of simulating both the chemical and the physical factors that affect hydrologic transport must be available. Several models for conducting such simulation are presently available. However,the input parameters used in these models are highly variable, and the accuracy of parameter measurement must be considered in evaluating the reliability of simulated results

  18. Simulated responses of streams and ponds to groundwater withdrawals and wastewater return flows in southeastern Massachusetts

    Science.gov (United States)

    Carlson, Carl S.; Walter, Donald A.; Barbaro, Jeffrey R.

    2015-12-21

    Water use, such as withdrawals, wastewater return flows, and interbasin transfers, can alter streamflow regimes, water quality, and the integrity of aquatic habitat and affect the availability of water for human and ecosystem needs. To provide the information needed to determine alteration of streamflows and pond water levels in southeastern Massachusetts, existing groundwater models of the Plymouth-Carver region and western (Sagamore flow lens) and eastern (Monomoy flow lens) Cape Cod were used to delineate subbasins and simulate long-term average and average monthly streamflows and pond levels for a series of water-use conditions. Model simulations were used to determine the extent to which streamflows and pond levels were altered by comparing simulated streamflows and pond levels under predevelopment conditions with streamflows and pond levels under pumping only and pumping with wastewater return flow conditions. The pumping and wastewater return flow rates used in this study are the same as those used in previously published U.S. Geological Survey studies in southeastern Massachusetts and represent the period from 2000 to 2005. Streamflow alteration for the nontidal portions of streams in southeastern Massachusetts was evaluated within and at the downstream outlets of 78 groundwater subbasins delineated for this study. Evaluation of streamflow alteration at subbasin outlets is consistent with the approach used by the U.S. Geological Survey for the topographically derived subbasins in the rest of Massachusetts.

  19. Groundwater: A review of the 1989 literature

    International Nuclear Information System (INIS)

    Miller, C.T.; Mayer, A.S.

    1990-01-01

    This review was prepared under the auspices of the WPCF Research Committee of the annual Literature Review issue of the Journal; because of logistical reasons it could not be published in June. However, in view of the growing importance of the subject, the review is presented here as a supplement to the June Literature Review issue that has not been through the Journal peer review process. In this review, distinctions are made between single-, two-, and three-phase systems. Single-phase systems refer to groundwater systems subjected to saturated flow conditions, whereas the two- and three-phase systems include groundwater systems subjected to unsaturated flow conditions, or conditions influenced by immiscible organic fluids such as petroleum products. Within the single-, two-, and three-phase system categories, subdivisions are made between physical, chemical, or biological processes such as hydrodynamics, sorption/desorption, chemical reactions, and biodegradation. Specialized areas such as radon and radionuclide transport, facilitated transport, and saline groundwaters also are treated separately. Rounding out this year's review, papers concerning groundwater quality monitoring, remediation, and management are discussed

  20. California’s Groundwater Regime: The Cadiz Case

    Directory of Open Access Journals (Sweden)

    Julia Sizek

    2018-01-01

    Full Text Available Recent California legislation has promised solutions to longstanding problems in groundwater management through an emphasis on management of groundwater itself, rather than on the rights of overlying property owners. In this short communication, I argue that the promises of scientific management relies on property law and jurisdiction and therefore that scientific claims about the water itself are less important than private property claims in the case of a Cadiz Inc.’s proposed groundwater extraction project in Southeastern California. While private property in land insulates Cadiz Inc. (Los Angeles, CA, USA from political contestation, opposition to the project has increasingly focused on the right to transport and transfer water through lands not held by Cadiz Inc. This legal strategy points to how California groundwater law is still fundamentally ruled by private property in land, which shifts the grounds of environmental politics from extraction itself to the transport of extracted materials. This case serves as a good example of the intersection of political ecology and legal geography.