A generalised groundwater flow equation using the concept of non ...
African Journals Online (AJOL)
The classical Darcy law is generalised by regarding the water flow as a function of a non-integer order derivative of the piezometric head. This generalised law and the law of conservation of mass are then used to derive a new equation for groundwater flow. Numerical solutions of this equation for various fractional orders of ...
A generalised groundwater flow equation using the concept of non ...
African Journals Online (AJOL)
2006-01-01
Jan 1, 2006 ... 2 Institute for Groundwater Studies, University of the Free State, PO Box 339, Bloemfontein, South Africa. Abstract ... Keywords: porous media, Darcy Law, integro-differential equations .... f(x) satisfies the boundary conditions.
Directory of Open Access Journals (Sweden)
M. L. Kavvas
2017-10-01
Full Text Available Using fractional calculus, a dimensionally consistent governing equation of transient, saturated groundwater flow in fractional time in a multi-fractional confined aquifer is developed. First, a dimensionally consistent continuity equation for transient saturated groundwater flow in fractional time and in a multi-fractional, multidimensional confined aquifer is developed. For the equation of water flux within a multi-fractional multidimensional confined aquifer, a dimensionally consistent equation is also developed. The governing equation of transient saturated groundwater flow in a multi-fractional, multidimensional confined aquifer in fractional time is then obtained by combining the fractional continuity and water flux equations. To illustrate the capability of the proposed governing equation of groundwater flow in a confined aquifer, a numerical application of the fractional governing equation to a confined aquifer groundwater flow problem was also performed.
Analytical Solutions of a Space-Time Fractional Derivative of Groundwater Flow Equation
Directory of Open Access Journals (Sweden)
Abdon Atangana
2014-01-01
Full Text Available The classical Darcy law is generalized by regarding the water flow as a function of a noninteger order derivative of the piezometric head. This generalized law and the law of conservation of mass are then used to derive a new equation for groundwater flow. Two methods including Frobenius and Adomian decomposition method are used to obtain an asymptotic analytical solution to the generalized groundwater flow equation. The solution obtained via Frobenius method is valid in the vicinity of the borehole. This solution is in perfect agreement with the data observed from the pumping test performed by the institute for groundwater study on one of their boreholes settled on the test site of the University of the Free State. The test consisted of the pumping of the borehole at the constant discharge rate Q and monitoring the piezometric head for 350 minutes. Numerical solutions obtained via Adomian method are compared with the Barker generalized radial flow model for which a fractal dimension for the flow is assumed. Proposition for uncertainties in groundwater studies was given.
M. L. Kavvas; T. Tu; A. Ercan; J. Polsinelli
2017-01-01
Using fractional calculus, a dimensionally consistent governing equation of transient, saturated groundwater flow in fractional time in a multi-fractional confined aquifer is developed. First, a dimensionally consistent continuity equation for transient saturated groundwater flow in fractional time and in a multi-fractional, multidimensional confined aquifer is developed. For the equation of water flux within a multi-fractional multidimensional confined aquifer, a dimensionally...
Birdsell, D.; Karra, S.; Rajaram, H.
2017-12-01
The governing equations for subsurface flow codes in deformable porous media are derived from the fluid mass balance equation. One class of these codes, which we call general subsurface flow (GSF) codes, does not explicitly track the motion of the solid porous media but does accept general constitutive relations for porosity, density, and fluid flux. Examples of GSF codes include PFLOTRAN, FEHM, STOMP, and TOUGH2. Meanwhile, analytical and numerical solutions based on the groundwater flow equation have assumed forms for porosity, density, and fluid flux. We review the derivation of the groundwater flow equation, which uses the form of Darcy's equation that accounts for the velocity of fluids with respect to solids and defines the soil matrix compressibility accordingly. We then show how GSF codes have a different governing equation if they use the form of Darcy's equation that is written only in terms of fluid velocity. The difference is seen in the porosity change, which is part of the specific storage term in the groundwater flow equation. We propose an alternative definition of soil matrix compressibility to correct for the untracked solid velocity. Simulation results show significantly less error for our new compressibility definition than the traditional compressibility when compared to analytical solutions from the groundwater literature. For example, the error in one calculation for a pumped sandstone aquifer goes from 940 to <70 Pa when the new compressibility is used. Code users and developers need to be aware of assumptions in the governing equations and constitutive relations in subsurface flow codes, and our newly-proposed compressibility function should be incorporated into GSF codes.
Hill, Mary C.
1990-01-01
This report documents PCG2 : a numerical code to be used with the U.S. Geological Survey modular three-dimensional, finite-difference, ground-water flow model . PCG2 uses the preconditioned conjugate-gradient method to solve the equations produced by the model for hydraulic head. Linear or nonlinear flow conditions may be simulated. PCG2 includes two reconditioning options : modified incomplete Cholesky preconditioning, which is efficient on scalar computers; and polynomial preconditioning, which requires less computer storage and, with modifications that depend on the computer used, is most efficient on vector computers . Convergence of the solver is determined using both head-change and residual criteria. Nonlinear problems are solved using Picard iterations. This documentation provides a description of the preconditioned conjugate gradient method and the two preconditioners, detailed instructions for linking PCG2 to the modular model, sample data inputs, a brief description of PCG2, and a FORTRAN listing.
Monitoring probe for groundwater flow
Looney, B.B.; Ballard, S.
1994-08-23
A monitoring probe for detecting groundwater migration is disclosed. The monitor features a cylinder made of a permeable membrane carrying an array of electrical conductivity sensors on its outer surface. The cylinder is filled with a fluid that has a conductivity different than the groundwater. The probe is placed in the ground at an area of interest to be monitored. The fluid, typically saltwater, diffuses through the permeable membrane into the groundwater. The flow of groundwater passing around the permeable membrane walls of the cylinder carries the conductive fluid in the same general direction and distorts the conductivity field measured by the sensors. The degree of distortion from top to bottom and around the probe is precisely related to the vertical and horizontal flow rates, respectively. The electrical conductivities measured by the sensors about the outer surface of the probe are analyzed to determine the rate and direction of the groundwater flow. 4 figs.
Evaluating groundwater flow using passive electrical measurements
Voytek, E.; Revil, A.; Singha, K.
2016-12-01
Accurate quantification of groundwater flow patterns, both in magnitude and direction, is a necessary component of evaluating any hydrologic system. Groundwater flow patterns are often determined using a dense network of wells or piezometers, which can be limited due to logistical or regulatory constraints. The self-potential (SP) method, a passive geophysical technique that relies on currents generated by water movement through porous materials, is a re-emerging alternative or addition to traditional piezometer networks. Naturally generated currents can be measured as voltage differences at the ground surface using only two electrodes, or a more complex electrode array. While the association between SP measurements and groundwater flow was observed as early as 1890s, the method has seen resurgence in hydrology since the governing equations were refined in the 1980s. The method can be used to analyze hydrologic processes at various temporal and spatial scales. Here we present the results of multiple SP surveys collected a multiple scales (1 to 10s of meters). Here single SP grid surveys are used to evaluate flow patterns through artic hillslopes at a discrete point in time. Additionally, a coupled groundwater and electrical model is used to analyze multiple SP data sets to evaluate seasonal changes in groundwater flow through an alpine meadow.
Global scale groundwater flow model
Sutanudjaja, Edwin; de Graaf, Inge; van Beek, Ludovicus; Bierkens, Marc
2013-04-01
As the world's largest accessible source of freshwater, groundwater plays 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 sustains water flows in streams, rivers, lakes and wetlands, and thus supports ecosystem habitat and biodiversity, while its large natural storage provides a buffer against water shortages. Yet, the current generation of global scale hydrological models does not include a groundwater flow component that is a crucial part of the hydrological cycle and allows the simulation of groundwater head dynamics. In this study we present a steady-state MODFLOW (McDonald and Harbaugh, 1988) groundwater model on the global scale at 5 arc-minutes resolution. Aquifer schematization and properties of this groundwater model were developed from available global lithological model (e.g. Dürr et al., 2005; Gleeson et al., 2010; Hartmann and Moorsdorff, in press). We force the groundwtaer model with the output from the large-scale hydrological model PCR-GLOBWB (van Beek et al., 2011), specifically the long term net groundwater recharge and average surface water levels derived from routed channel discharge. We validated calculated groundwater heads and depths with available head observations, from different regions, including the North and South America and Western Europe. Our results show that it is feasible to build a relatively simple global scale groundwater model using existing information, and estimate water table depths within acceptable accuracy in many parts of the world.
Groundwater flow model and its implications for contaminant behavior
African Journals Online (AJOL)
What sets hydrogeology apart from many of the other geosciences is an emphasis on treating problems mathematically. The mathematical approach involves representing a groundwater process by an equation and solving that equation. These equations are fundamental to the quantitative treatment of flow and provide the ...
Modeling groundwater flow on MPPs
International Nuclear Information System (INIS)
Ashby, S.F.; Falgout, R.D.; Smith, S.G.; Tompson, A.F.B.
1993-10-01
The numerical simulation of groundwater flow in three-dimensional heterogeneous porous media is examined. To enable detailed modeling of large contaminated sites, preconditioned iterative methods and massively parallel computing power are combined in a simulator called PARFLOW. After describing this portable and modular code, some numerical results are given, including one that demonstrates the code's scalability
Modeling groundwater flow and quality
Konikow, Leonard F.; Glynn, Pierre D.; Selinus, Olle
2013-01-01
In most areas, rocks in the subsurface are saturated with water at relatively shallow depths. The top of the saturated zone—the water table—typically occurs anywhere from just below land surface to hundreds of feet below the land surface. Groundwater generally fills all pore spaces below the water table and is part of a continuous dynamic flow system, in which the fluid is moving at velocities ranging from feet per millennia to feet per day (Fig. 33.1). While the water is in close contact with the surfaces of various minerals in the rock material, geochemical interactions between the water and the rock can affect the chemical quality of the water, including pH, dissolved solids composition, and trace-elements content. Thus, flowing groundwater is a major mechanism for the transport of chemicals from buried rocks to the accessible environment, as well as a major pathway from rocks to human exposure and consumption. Because the mineral composition of rocks is highly variable, as is the solubility of various minerals, the human-health effects of groundwater consumption will be highly variable.
Wetterich, C.
2018-06-01
We propose a closed gauge-invariant functional flow equation for Yang-Mills theories and quantum gravity that only involves one macroscopic gauge field or metric. It is based on a projection on physical and gauge fluctuations. Deriving this equation from a functional integral we employ the freedom in the precise choice of the macroscopic field and the effective average action in order to realize a closed and simple form of the flow equation.
Deep groundwater flow at Palmottu
International Nuclear Information System (INIS)
Niini, H.; Vesterinen, M.; Tuokko, T.
1993-01-01
Further observations, measurements, and calculations aimed at determining the groundwater flow regimes and periodical variations in flow at deeper levels were carried out in the Lake Palmottu (a natural analogue study site for radioactive waste disposal in southwestern Finland) drainage basin. These water movements affect the migration of radionuclides from the Palmottu U-Th deposit. The deep water flow is essentially restricted to the bedrock fractures which developed under, and are still affected by, the stress state of the bedrock. Determination of the detailed variations was based on fracture-tectonic modelling of the 12 most significant underground water-flow channels that cross the surficial water of the Palmottu area. According to the direction of the hydraulic gradient the deep water flow is mostly outwards from the Palmottu catchment but in the westernmost section it is partly towards the centre. Estimation of the water flow through the U-Th deposit by the water-balance method is still only approximate and needs continued observation series and improved field measurements
Numerical optimization using flow equations
Punk, Matthias
2014-12-01
We develop a method for multidimensional optimization using flow equations. This method is based on homotopy continuation in combination with a maximum entropy approach. Extrema of the optimizing functional correspond to fixed points of the flow equation. While ideas based on Bayesian inference such as the maximum entropy method always depend on a prior probability, the additional step in our approach is to perform a continuous update of the prior during the homotopy flow. The prior probability thus enters the flow equation only as an initial condition. We demonstrate the applicability of this optimization method for two paradigmatic problems in theoretical condensed matter physics: numerical analytic continuation from imaginary to real frequencies and finding (variational) ground states of frustrated (quantum) Ising models with random or long-range antiferromagnetic interactions.
Harbaugh, Arlen W.; Banta, Edward R.; Hill, Mary C.; McDonald, Michael G.
2000-01-01
MODFLOW is a computer program that numerically solves the three-dimensional ground-water flow equation for a porous medium by using a finite-difference method. Although MODFLOW was designed to be easily enhanced, the design was oriented toward additions to the ground-water flow equation. Frequently there is a need to solve additional equations; for example, transport equations and equations for estimating parameter values that produce the closest match between model-calculated heads and flows and measured values. This report documents a new version of MODFLOW, called MODFLOW-2000, which is designed to accommodate the solution of equations in addition to the ground-water flow equation. This report is a user's manual. It contains an overview of the old and added design concepts, documents one new package, and contains input instructions for using the model to solve the ground-water flow equation.
Complex groundwater flow systems as traveling agent models
Directory of Open Access Journals (Sweden)
Oliver López Corona
2014-10-01
Full Text Available Analyzing field data from pumping tests, we show that as with many other natural phenomena, groundwater flow exhibits complex dynamics described by 1/f power spectrum. This result is theoretically studied within an agent perspective. Using a traveling agent model, we prove that this statistical behavior emerges when the medium is complex. Some heuristic reasoning is provided to justify both spatial and dynamic complexity, as the result of the superposition of an infinite number of stochastic processes. Even more, we show that this implies that non-Kolmogorovian probability is needed for its study, and provide a set of new partial differential equations for groundwater flow.
International Nuclear Information System (INIS)
Crowe, C.T.
1975-01-01
General features of a vapor-droplet flow are discussed and the equations expressing the conservation of mass, momentum, and energy for the vapor, liquid, and mixture using the control volume approach are derived. The phenomenological laws describing the exchange of mass, momentum, and energy between phases are also reviewed. The results have application to development of water-dominated geothermal resources
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
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
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.
The effects of radiogenic heat on groundwater flow
International Nuclear Information System (INIS)
Beddoes, R.J.; Tammemagi, H.Y.
1986-03-01
The effects of radiogenic heat released by a nuclear waste repository on the groundwater flow in the neighbouring rock mass is reviewed. The report presents an overview of the hydrogeologic properties of crystalline rocks in the Canadian Shield and also describes the mathematical theory of groundwater flow and heat transfer in both porous media and fractured rock. Numerical methods for the solution of the governing equations are described. A number of case histories are described where analyses of flow systems have been performed both with and without radiogenic heat sources. A number of relevant topics are reviewed such as the role of the porous medium model, boundary conditions and, most importantly, the role of complex coupled processes where the effects of heat and water flow are intertwined with geochemical and mechanical processes. The implications to radioactive waste disposal are discussed
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
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
Regression modeling of ground-water flow
Cooley, R.L.; Naff, R.L.
1985-01-01
Nonlinear multiple regression methods are developed to model and analyze groundwater flow systems. Complete descriptions of regression methodology as applied to groundwater flow models allow scientists and engineers engaged in flow modeling to apply the methods to a wide range of problems. Organization of the text proceeds from an introduction that discusses the general topic of groundwater flow modeling, to a review of basic statistics necessary to properly apply regression techniques, and then to the main topic: exposition and use of linear and nonlinear regression to model groundwater flow. Statistical procedures are given to analyze and use the regression models. A number of exercises and answers are included to exercise the student on nearly all the methods that are presented for modeling and statistical analysis. Three computer programs implement the more complex methods. These three are a general two-dimensional, steady-state regression model for flow in an anisotropic, heterogeneous porous medium, a program to calculate a measure of model nonlinearity with respect to the regression parameters, and a program to analyze model errors in computed dependent variables such as hydraulic head. (USGS)
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
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.
Analysis of groundwater flow beneath ice sheets
Energy Technology Data Exchange (ETDEWEB)
Boulton, G. S.; Zatsepin, S.; Maillot, B. [Univ. of Edinburgh (United Kingdom). Dept. of Geology and Geophysics
2001-03-01
The large-scale pattern of subglacial groundwater flow beneath European ice sheets was analysed in a previous report. It was based on a two-dimensional flowline model. In this report, the analysis is extended to three dimensions by exploring the interactions between groundwater and tunnel flow. A theory is developed which suggests that the large-scale geometry of the hydraulic system beneath an ice sheet is a coupled, self-organising system. In this system the pressure distribution along tunnels is a function of discharge derived from basal meltwater delivered to tunnels by groundwater flow, and the pressure along tunnels itself sets the base pressure which determines the geometry of catchments and flow towards the tunnel. The large-scale geometry of tunnel distribution is a product of the pattern of basal meltwater production and the transmissive properties of the bed. The tunnel discharge from the ice margin of the glacier, its seasonal fluctuation and the sedimentary characteristics of eskers are largely determined by the discharge of surface meltwater which penetrates to the bed in the terminal zone. The theory explains many of the characteristics of esker systems and can account for tunnel valleys. It is concluded that the large-scale hydraulic regime beneath ice sheets is largely a consequence of groundwater/tunnel flow interactions and that it is essential similar to non-glacial hydraulic regimes. Experimental data from an Icelandic glacier, which demonstrates measured relationships between subglacial tunnel flow and groundwater flow during the transition from summer to winter seasons for a modern glacier, and which support the general conclusions of the theory is summarised in an appendix.
Analysis of groundwater flow beneath ice sheets
International Nuclear Information System (INIS)
Boulton, G. S.; Zatsepin, S.; Maillot, B.
2001-03-01
The large-scale pattern of subglacial groundwater flow beneath European ice sheets was analysed in a previous report. It was based on a two-dimensional flowline model. In this report, the analysis is extended to three dimensions by exploring the interactions between groundwater and tunnel flow. A theory is developed which suggests that the large-scale geometry of the hydraulic system beneath an ice sheet is a coupled, self-organising system. In this system the pressure distribution along tunnels is a function of discharge derived from basal meltwater delivered to tunnels by groundwater flow, and the pressure along tunnels itself sets the base pressure which determines the geometry of catchments and flow towards the tunnel. The large-scale geometry of tunnel distribution is a product of the pattern of basal meltwater production and the transmissive properties of the bed. The tunnel discharge from the ice margin of the glacier, its seasonal fluctuation and the sedimentary characteristics of eskers are largely determined by the discharge of surface meltwater which penetrates to the bed in the terminal zone. The theory explains many of the characteristics of esker systems and can account for tunnel valleys. It is concluded that the large-scale hydraulic regime beneath ice sheets is largely a consequence of groundwater/tunnel flow interactions and that it is essential similar to non-glacial hydraulic regimes. Experimental data from an Icelandic glacier, which demonstrates measured relationships between subglacial tunnel flow and groundwater flow during the transition from summer to winter seasons for a modern glacier, and which support the general conclusions of the theory is summarised in an appendix
Geomorphic aspects of groundwater flow
LaFleur, Robert G.
The many roles that groundwater plays in landscape evolution are becoming more widely appreciated. In this overview, three major categories of groundwater processes and resulting landforms are considered: (1) Dissolution creates various karst geometries, mainly in carbonate rocks, in response to conditions of recharge, geologic setting, lithology, and groundwater circulation. Denudation and cave formation rates can be estimated from kinetic and hydraulic parameters. (2) Groundwater weathering generates regoliths of residual alteration products at weathering fronts, and subsequent exhumation exposes corestones, flared slopes, balanced rocks, domed inselbergs, and etchplains of regional importance. Groundwater relocation of dissolved salts creates duricrusts of various compositions, which become landforms. (3) Soil and rock erosion by groundwater processes include piping, seepage erosion, and sapping, important agents in slope retreat and headward gully migration. Thresholds and limits are important in many chemical and mechanical groundwater actions. A quantitative, morphometric approach to groundwater landforms and processes is exemplified by selected studies in carbonate and clastic terrains of ancient and recent origins. Résumé Les rôles variés joués par les eaux souterraines dans l'évolution des paysages deviennent nettement mieux connus. La revue faite ici prend en considération trois grandes catégories de processus liés aux eaux souterraines et les formes associées: (1) La dissolution crée des formes karstiques variées, surtout dans les roches carbonatées, en fonction des conditions d'alimentation, du cadre géologique, de la lithologie et de la circulation des eaux souterraines. Les taux d'érosion et de formation des grottes peuvent être estimés à partir de paramètres cinétiques et hydrauliques. (2) L'érosion par les eaux souterraines donne naissance à des régolites, résidus d'altération sur des fronts d'altération, et l'exhumation r
Sensitivity Analysis for Steady State Groundwater Flow Using Adjoint Operators
Sykes, J. F.; Wilson, J. L.; Andrews, R. W.
1985-03-01
Adjoint sensitivity theory is currently being considered as a potential method for calculating the sensitivity of nuclear waste repository performance measures to the parameters of the system. For groundwater flow systems, performance measures of interest include piezometric heads in the vicinity of a waste site, velocities or travel time in aquifers, and mass discharge to biosphere points. The parameters include recharge-discharge rates, prescribed boundary heads or fluxes, formation thicknesses, and hydraulic conductivities. The derivative of a performance measure with respect to the system parameters is usually taken as a measure of sensitivity. To calculate sensitivities, adjoint sensitivity equations are formulated from the equations describing the primary problem. The solution of the primary problem and the adjoint sensitivity problem enables the determination of all of the required derivatives and hence related sensitivity coefficients. In this study, adjoint sensitivity theory is developed for equations of two-dimensional steady state flow in a confined aquifer. Both the primary flow equation and the adjoint sensitivity equation are solved using the Galerkin finite element method. The developed computer code is used to investigate the regional flow parameters of the Leadville Formation of the Paradox Basin in Utah. The results illustrate the sensitivity of calculated local heads to the boundary conditions. Alternatively, local velocity related performance measures are more sensitive to hydraulic conductivities.
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
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
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
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)
Patterns in groundwater chemistry resulting from groundwater flow
Stuyfzand, Pieter J.
Groundwater flow influences hydrochemical patterns because flow reduces mixing by diffusion, carries the chemical imprints of biological and anthropogenic changes in the recharge area, and leaches the aquifer system. Global patterns are mainly dictated by differences in the flux of meteoric water passing through the subsoil. Within individual hydrosomes (water bodies with a specific origin), the following prograde evolution lines (facies sequence) normally develop in the direction of groundwater flow: from strong to no fluctuations in water quality, from polluted to unpolluted, from acidic to basic, from oxic to anoxic-methanogenic, from no to significant base exchange, and from fresh to brackish. This is demonstrated for fresh coastal-dune groundwater in the Netherlands. In this hydrosome, the leaching of calcium carbonate as much as 15m and of adsorbed marine cations (Na+, K+, and Mg2+) as much as 2500m in the flow direction is shown to correspond with about 5000yr of flushing since the beach barrier with dunes developed. Recharge focus areas in the dunes are evidenced by groundwater displaying a lower prograde quality evolution than the surrounding dune groundwater. Artificially recharged Rhine River water in the dunes provides distinct hydrochemical patterns, which display groundwater flow, mixing, and groundwater ages. Résumé Les écoulements souterrains influencent les différents types hydrochimiques, parce que l'écoulement réduit le mélange par diffusion, porte les marques chimiques de changements biologiques et anthropiques dans la zone d'alimentation et lessive le système aquifère. Ces types dans leur ensemble sont surtout déterminés par des différences dans le flux d'eau météorique traversant le sous-sol. Dans les "hydrosomes" (masses d'eau d'origine déterminée), les lignes marquant une évolution prograde (séquence de faciès) se développent normalement dans la direction de l'écoulement souterrain : depuis des fluctuations fortes de la
Regional groundwater flow in hard rocks
Energy Technology Data Exchange (ETDEWEB)
Pacheco, Fernando A.L., E-mail: fpacheco@utad.pt
2015-02-15
The territory of continental Portugal has a geologic history marked by the Hercynian orogeny, and to the north of this country the Hercynian large-scale tectonic structures are typically represented by long and deep NW–SE trending ductile shear zones and NNE–SSW trending fragile faults. These structures are elements of mineral and thermal water circuits that discharge as springs in more than one hundred locations. The purpose of this study is to investigate if these structures are also used by shallower non-mineral groundwater, integrated in a large-scale regional flow system. Using an original combination of water balance and recession flow models, it was possible to calculate catchment turnover times based solely on groundwater discharge rates and recession flow parameters. These times were then used to classify a group of 46 watersheds as closed or open basins, and among the later class to identify source and sink basins, based on innovative interpretations of relationships between turnover time and catchment area. By definition, source basins transfer groundwater to sink basins and altogether form a regional flow system. Using a Geographic Information System, it could be demonstrated the spatial association of open basins to the Hercynian ductile and fragile tectonic structures and hence to classify the basins as discharge cells of a regional flow system. Most of the studied watersheds are sub-basins of the Douro River basin, one of the largest regional catchments in the Iberian Peninsula, being located in its mouth area. Because the largest part of open basins is sink, which by definition tends to dominate in the mouth area of regional catchments, it is proposed as an extension of the studied area conceptual boundaries towards the Douro River basin headwaters, where the corresponding sources could be searched for. - Highlights: • Introduce a method to distinguish open from closed groundwater basins • Identify structural elements of a regional flow
Regional groundwater flow in hard rocks
International Nuclear Information System (INIS)
Pacheco, Fernando A.L.
2015-01-01
The territory of continental Portugal has a geologic history marked by the Hercynian orogeny, and to the north of this country the Hercynian large-scale tectonic structures are typically represented by long and deep NW–SE trending ductile shear zones and NNE–SSW trending fragile faults. These structures are elements of mineral and thermal water circuits that discharge as springs in more than one hundred locations. The purpose of this study is to investigate if these structures are also used by shallower non-mineral groundwater, integrated in a large-scale regional flow system. Using an original combination of water balance and recession flow models, it was possible to calculate catchment turnover times based solely on groundwater discharge rates and recession flow parameters. These times were then used to classify a group of 46 watersheds as closed or open basins, and among the later class to identify source and sink basins, based on innovative interpretations of relationships between turnover time and catchment area. By definition, source basins transfer groundwater to sink basins and altogether form a regional flow system. Using a Geographic Information System, it could be demonstrated the spatial association of open basins to the Hercynian ductile and fragile tectonic structures and hence to classify the basins as discharge cells of a regional flow system. Most of the studied watersheds are sub-basins of the Douro River basin, one of the largest regional catchments in the Iberian Peninsula, being located in its mouth area. Because the largest part of open basins is sink, which by definition tends to dominate in the mouth area of regional catchments, it is proposed as an extension of the studied area conceptual boundaries towards the Douro River basin headwaters, where the corresponding sources could be searched for. - Highlights: • Introduce a method to distinguish open from closed groundwater basins • Identify structural elements of a regional flow
New approach for simulating groundwater flow in discrete fracture network
Fang, H.; Zhu, J.
2017-12-01
In this study, we develop a new approach to calculate groundwater flowrate and hydraulic head distribution in two-dimensional discrete fracture network (DFN) where both laminar and turbulent flows co-exist in individual fractures. The cubic law is used to calculate hydraulic head distribution and flow behaviors in fractures where flow is laminar, while the Forchheimer's law is used to quantify turbulent flow behaviors. Reynolds number is used to distinguish flow characteristics in individual fractures. The combination of linear and non-linear equations is solved iteratively to determine flowrates in all fractures and hydraulic heads at all intersections. We examine potential errors in both flowrate and hydraulic head from the approach of uniform flow assumption. Applying the cubic law in all fractures regardless of actual flow conditions overestimates the flowrate when turbulent flow may exist while applying the Forchheimer's law indiscriminately underestimate the flowrate when laminar flows exist in the network. The contrast of apertures of large and small fractures in the DFN has significant impact on the potential errors of using only the cubic law or the Forchheimer's law. Both the cubic law and Forchheimer's law simulate similar hydraulic head distributions as the main difference between these two approaches lies in predicting different flowrates. Fracture irregularity does not significantly affect the potential errors from using only the cubic law or the Forchheimer's law if network configuration remains similar. Relative density of fractures does not significantly affect the relative performance of the cubic law and Forchheimer's law.
Gravity-driven groundwater flow and slope failure potential: 1. Elastic effective-stress model
Iverson, Richard M.; Reid, Mark E.
1992-01-01
Hilly or mountainous topography influences gravity-driven groundwater flow and the consequent distribution of effective stress in shallow subsurface environments. Effective stress, in turn, influences the potential for slope failure. To evaluate these influences, we formulate a two-dimensional, steady state, poroelastic model. The governing equations incorporate groundwater effects as body forces, and they demonstrate that spatially uniform pore pressure changes do not influence effective stresses. We implement the model using two finite element codes. As an illustrative case, we calculate the groundwater flow field, total body force field, and effective stress field in a straight, homogeneous hillslope. The total body force and effective stress fields show that groundwater flow can influence shear stresses as well as effective normal stresses. In most parts of the hillslope, groundwater flow significantly increases the Coulomb failure potential Φ, which we define as the ratio of maximum shear stress to mean effective normal stress. Groundwater flow also shifts the locus of greatest failure potential toward the slope toe. However, the effects of groundwater flow on failure potential are less pronounced than might be anticipated on the basis of a simpler, one-dimensional, limit equilibrium analysis. This is a consequence of continuity, compatibility, and boundary constraints on the two-dimensional flow and stress fields, and it points to important differences between our elastic continuum model and limit equilibrium models commonly used to assess slope stability.
Reconstruction of dynamical equations for traffic flow
Kriso, S.; Friedrich, R.; Peinke, J.; Wagner, P.
2001-01-01
Traffic flow data collected by an induction loop detector on the highway close to Koeln-Nord are investigated with respect to their dynamics including the stochastic content. In particular we present a new method, with which the flow dynamics can be extracted directly from the measured data. As a result a Langevin equation for the traffic flow is obtained. From the deterministic part of the flow dynamics, stable fixed points are extracted and set into relation with common features of the fund...
Five-point Element Scheme of Finite Analytic Method for Unsteady Groundwater Flow
Institute of Scientific and Technical Information of China (English)
Xiang Bo; Mi Xiao; Ji Changming; Luo Qingsong
2007-01-01
In order to improve the finite analytic method's adaptability for irregular unit, by using coordinates rotation technique this paper establishes a five-point element scheme of finite analytic method. It not only solves unsteady groundwater flow equation but also gives the boundary condition. This method can be used to calculate the three typical questions of groundwater. By compared with predecessor's computed result, the result of this method is more satisfactory.
Radionuclides in groundwater flow system understanding
Erőss, Anita; Csondor, Katalin; Horváth, Ákos; Mádl-Szőnyi, Judit; Surbeck, Heinz
2017-04-01
Using radionuclides is a novel approach to characterize fluids of groundwater flow systems and understand their mixing. Particularly, in regional discharge areas, where different order flow systems convey waters with different temperature, composition and redox-state to the discharge zone. Radium and uranium are redox-sensitive parameters, which causes fractionation along groundwater flow paths. Discharging waters of regional flow systems are characterized by elevated total dissolved solid content (TDS), temperature and by reducing conditions, and therefore with negligible uranium content, whereas local flow systems have lower TDS and temperature and represent oxidizing environments, and therefore their radium content is low. Due to the short transit time, radon may appear in local systems' discharge, where its source is the soil zone. However, our studies revealed the importance of FeOOH precipitates as local radon sources throughout the adsorption of radium transported by the thermal waters of regional flow systems. These precipitates can form either by direct oxidizing of thermal waters at discharge, or by mixing of waters with different redox state. Therefore elevated radon content often occurs in regional discharge areas as well. This study compares the results of geochemical studies in three thermal karst areas in Hungary, focusing on radionuclides as natural tracers. In the Buda Thermal Karst, the waters of the distinct discharge areas are characterized by different temperature and chemical composition. In the central discharge area both lukewarm (20-35°C, 770-980 mg/l TDS) and thermal waters (40-65°C, 800-1350 mg/l TDS), in the South only thermal water discharge (33-43°C, 1450-1700 mg/l TDS) occur. Radionuclides helped to identify mixing of fluids and to infer the temperature and chemical composition of the end members for the central discharge area. For the southern discharge zone mixing components could not be identified, which suggests different cave
Modelling framework for groundwater flow at Sellafield
International Nuclear Information System (INIS)
Hooper, A.J.; Billington, D.E.; Herbert, A.W.
1995-01-01
The principal objective of Nirex is to develop a single deep geological repository for the safe disposal of low- and intermediate-level radioactive waste. In safety assessment, use is made of a variety of conceptual models that form the basis for modelling of the pathways by which radionuclides might return to the environment. In this paper, the development of a conceptual model for groundwater flow and transport through fractured rock on the various scales of interest is discussed. The approach is illustrated by considering how some aspects of the conceptual model are developed in particular numerical models. These representations of the conceptual model use fracture network geometries based on realistic rock properties. (author). refs., figs., tabs
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
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)
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.)
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
Computer modeling of ground-water flow at the Savannah River Plant
International Nuclear Information System (INIS)
Root, R.W. Jr.
1979-01-01
Mathematical equations describing ground-water flow are used in a computer model being developed to predict the space-time distribution of hydraulic head beneath a part of the Savannah River Plant site. These equations are solved by a three-dimensional finite-difference scheme. Preliminary calibration of the hydraulic head model has been completed and calculated results compare well with water-level changes observed in the field. 10 figures, 1 table
Study on the flow state of groundwater by isotope tracer
International Nuclear Information System (INIS)
Lin Tong; Chen Jiansheng; Chen Liang
2008-01-01
Radioisotope logging technique is an effective method to evaluate groundwater movement. Moving with the water, the isotope tracer distributes differently in different flow states. According to the depth and time distribution of radioactivity, flow state of the groundwater can be determined. In this paper, different flow states, i.e. laminar flow, turbulent flow and mixing flow, are analyzed, and calculation of the flow velocity is discussed. Also, we discuss how to distinguish the laminar flow part and turbulent part in a mixing flow. If one judges the flow state incorrectly, the error of flow velocity will be huge, hence the importance of flow state analysis. Finally, some problems in the practical projects and measuring methods are concluded. (authors)
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
Modeling groundwater flow to elliptical lakes and through multi-aquifer elliptical inhomogeneities
Bakker, Mark
2004-05-01
Two new analytic element solutions are presented for steady flow problems with elliptical boundaries. The first solution concerns groundwater flow to shallow elliptical lakes with leaky lake beds in a single-aquifer. The second solution concerns groundwater flow through elliptical cylinder inhomogeneities in a multi-aquifer system. Both the transmissivity of each aquifer and the resistance of each leaky layer may differ between the inside and the outside of an inhomogeneity. The elliptical inhomogeneity may be bounded on top by a shallow elliptical lake with a leaky lake bed. Analytic element solutions are obtained for both problems through separation of variables of the Laplace and modified-Helmholtz differential equations in elliptical coordinates. The resulting equations for the discharge potential consist of infinite sums of products of exponentials, trigonometric functions, and modified-Mathieu functions. The series are truncated but still fulfill the differential equation exactly; boundary conditions are met approximately, but up to machine accuracy provided enough terms are used. The head and flow may be computed analytically at any point in the aquifer. Examples are given of uniform flow through an elliptical lake, a well pumping near two elliptical lakes, and uniform flow through three elliptical inhomogeneities in a multi-aquifer system. Mathieu functions may be applied in a similar fashion to solve other groundwater flow problems in semi-confined aquifers and leaky aquifer systems with elliptical internal or external boundaries.
Interpreting Repeated Temperature-Depth Profiles for Groundwater Flow
Bense, Victor F.; Kurylyk, Barret L.; Daal, van Jonathan; Ploeg, van der Martine J.; Carey, Sean K.
2017-01-01
Temperature can be used to trace groundwater flows due to thermal disturbances of subsurface advection. Prior hydrogeological studies that have used temperature-depth profiles to estimate vertical groundwater fluxes have either ignored the influence of climate change by employing steady-state
General Separations Area (GSA) Groundwater Flow Model Update: Hydrostratigraphic Data
Energy Technology Data Exchange (ETDEWEB)
Bagwell, L. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Bennett, P. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Flach, G. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)
2017-02-21
This document describes the assembly, selection, and interpretation of hydrostratigraphic data for input to an updated groundwater flow model for the General Separations Area (GSA; Figure 1) at the Department of Energy’s (DOE) Savannah River Site (SRS). This report is one of several discrete but interrelated tasks that support development of an updated groundwater model (Bagwell and Flach, 2016).
Comparing groundwater recharge and base flow in the Bukmoongol ...
Indian Academy of Sciences (India)
model, also known as the Rorabaugh Method. (Rorabaugh 1960; Daniel 1976; Rutledge 2007b), estimates groundwater recharges for each stream- flow peak using the recession-curve-displacement method. It is based on an analytical model that describes groundwater discharge subsequent to recharge to the water table ...
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
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
Characterizing Groundwater Level and Flow Pattern in a Shallow ...
African Journals Online (AJOL)
Bheema
This study characterize groundwater yield and flow pattern on a shallow ... simple process of weathering, fractured fissure systems, networks of joints and ..... lowest yield in wells that are deeper than the mean well depth in the study area.
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.
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.)
Approaches to the simulation of unconfined flow and perched groundwater flow in MODFLOW
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.
Directory of Open Access Journals (Sweden)
Abdon Atangana
2014-01-01
Full Text Available The notion of uncertainty in groundwater hydrology is of great importance as it is known to result in misleading output when neglected or not properly accounted for. In this paper we examine this effect in groundwater flow models. To achieve this, we first introduce the uncertainties functions u as function of time and space. The function u accounts for the lack of knowledge or variability of the geological formations in which flow occur (aquifer in time and space. We next make use of Riemann-Liouville fractional derivatives that were introduced by Kobelev and Romano in 2000 and its approximation to modify the standard version of groundwater flow equation. Some properties of the modified Riemann-Liouville fractional derivative approximation are presented. The classical model for groundwater flow, in the case of density-independent flow in a uniform homogeneous aquifer is reformulated by replacing the classical derivative by the Riemann-Liouville fractional derivatives approximations. The modified equation is solved via the technique of green function and the variational iteration method.
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
Characterization of groundwater flow for near surface disposal facilities
International Nuclear Information System (INIS)
2001-02-01
The main objective of this report is to provide a description of the site investigation techniques and modelling approaches that can be used to characterise the flow of subsurface water at near surface disposal facilities in relation to the various development stages of the repositories. As one of the main goals of defining groundwater flow is to establish the possible contaminant migration, certain aspects related to groundwater transport are also described. Secondary objectives are to discuss the implications of various groundwater conditions with regard to the performance of the isolation systems
Research on flow characteristics of deep groundwater by environmental isotopes
Energy Technology Data Exchange (ETDEWEB)
Shimada, Jun; Miyaoka, Kunihide [Tsukuba Univ., Ibaraki (Japan); Sakurai, Hideyuki; Senoo, Muneaki; Kumata, Masahiro; Mukai, Masayuki; Watanabe, Kazuo; Ouchi, Misao
1996-01-01
In this research, as the technique for grasping the behavior of groundwater in deep rock bed which is important as the factor of disturbing the natural barrier in the formation disposal of high level radioactive waste, the method of utilizing the environmental isotopes contained in groundwater as natural tracer was taken up, and by setting up the concrete field of investigation, through the forecast of flow by the two or three dimensional groundwater flow analysis using a computer, the planning and execution of water sampling, the analysis of various environmental isotopes, the interpretation based on those results of measurement and so on, the effectiveness of the investigation technique used was verified, and the real state of the behavior of deep groundwater in the district being studied was clarified. In this research, Imaichi alluvial fan located in northern Kanto plain was taken as the object. In fiscal year 1996, three-dimensional steady state groundwater flow simulation was carried out based on the data related to shallow groundwater and surface water systems, and the places where active groundwater flow is expected were selected, and boring will be carried out there. The analysis model and the results are reported. (K.I.)
Assessing the velocity of the groundwater flow in bedrock fractures
International Nuclear Information System (INIS)
Taivassalo, V.; Poteri, A.
1994-10-01
Teollisuuden Voima Oy (TVO) is studying the crystalline bedrock in Finland for the final disposal of the spent nuclear fuel from its two reactors in Olkiluoto. Preliminary site investigations for five areas were carried out during 1987-1992. One part of the investigation programme was three-dimensional groundwater flow modelling. The numerical site-specific flow simulations were based on the concept of an equivalent porous continuum. The results include hydraulic head distributions, average groundwater flow rate routes. In this study, a novel approach was developed to evaluate the velocities of the water particles flowing in the fractured bedrock. (17 refs., 15 figs., 5 tabs.)
Groundwater flow modelling under ice sheet conditions. Scoping calculations
Energy Technology Data Exchange (ETDEWEB)
Jaquet, O.; Namar, R. (In2Earth Modelling Ltd (Switzerland)); Jansson, P. (Dept. of Physical Geography and Quaternary Geology, Stockholm Univ., Stockholm (Sweden))
2010-10-15
The potential impact of long-term climate changes has to be evaluated with respect to repository performance and safety. In particular, glacial periods of advancing and retreating ice sheet and prolonged permafrost conditions are likely to occur over the repository site. The growth and decay of ice sheets and the associated distribution of permafrost will affect the groundwater flow field and its composition. As large changes may take place, the understanding of groundwater flow patterns in connection to glaciations is an important issue for the geological disposal at long term. During a glacial period, the performance of the repository could be weakened by some of the following conditions and associated processes: - Maximum pressure at repository depth (canister failure). - Maximum permafrost depth (canister failure, buffer function). - Concentration of groundwater oxygen (canister corrosion). - Groundwater salinity (buffer stability). - Glacially induced earthquakes (canister failure). Therefore, the GAP project aims at understanding key hydrogeological issues as well as answering specific questions: - Regional groundwater flow system under ice sheet conditions. - Flow and infiltration conditions at the ice sheet bed. - Penetration depth of glacial meltwater into the bedrock. - Water chemical composition at repository depth in presence of glacial effects. - Role of the taliks, located in front of the ice sheet, likely to act as potential discharge zones of deep groundwater flow. - Influence of permafrost distribution on the groundwater flow system in relation to build-up and thawing periods. - Consequences of glacially induced earthquakes on the groundwater flow system. Some answers will be provided by the field data and investigations; the integration of the information and the dynamic characterisation of the key processes will be obtained using numerical modelling. Since most of the data are not yet available, some scoping calculations are performed using the
Groundwater flow modelling under ice sheet conditions. Scoping calculations
International Nuclear Information System (INIS)
Jaquet, O.; Namar, R.; Jansson, P.
2010-10-01
The potential impact of long-term climate changes has to be evaluated with respect to repository performance and safety. In particular, glacial periods of advancing and retreating ice sheet and prolonged permafrost conditions are likely to occur over the repository site. The growth and decay of ice sheets and the associated distribution of permafrost will affect the groundwater flow field and its composition. As large changes may take place, the understanding of groundwater flow patterns in connection to glaciations is an important issue for the geological disposal at long term. During a glacial period, the performance of the repository could be weakened by some of the following conditions and associated processes: - Maximum pressure at repository depth (canister failure). - Maximum permafrost depth (canister failure, buffer function). - Concentration of groundwater oxygen (canister corrosion). - Groundwater salinity (buffer stability). - Glacially induced earthquakes (canister failure). Therefore, the GAP project aims at understanding key hydrogeological issues as well as answering specific questions: - Regional groundwater flow system under ice sheet conditions. - Flow and infiltration conditions at the ice sheet bed. - Penetration depth of glacial meltwater into the bedrock. - Water chemical composition at repository depth in presence of glacial effects. - Role of the taliks, located in front of the ice sheet, likely to act as potential discharge zones of deep groundwater flow. - Influence of permafrost distribution on the groundwater flow system in relation to build-up and thawing periods. - Consequences of glacially induced earthquakes on the groundwater flow system. Some answers will be provided by the field data and investigations; the integration of the information and the dynamic characterisation of the key processes will be obtained using numerical modelling. Since most of the data are not yet available, some scoping calculations are performed using the
Groundwater flow and heterogeneous discharge into a seepage lake
DEFF Research Database (Denmark)
Kazmierczak, Jolanta; Müller, Sascha; Nilsson, B.
2016-01-01
with the lake remained under seemingly steady state conditions across seasons, a high spatial and temporal heterogeneity in the discharge to the lake was observed. The results showed that part of the groundwater flowing from the west passes beneath the lake and discharges at the eastern shore, where groundwater......Groundwater discharge into a seepage lake was investigated by combining flux measurements, hydrochemical tracers, geological information, and a telescopic modeling approach using first two-dimensional (2-D) regional then 2-D local flow and flow path models. Discharge measurements and hydrochemical...... tracers supplement each other. Discharge measurements yield flux estimates but rarely provide information about the origin and flow path of the water. Hydrochemical tracers may reveal the origin and flow path of the water but rarely provide any information about the flux. While aquifer interacting...
Mixed finite element simulations in two-dimensional groundwater flow problems
International Nuclear Information System (INIS)
Kimura, Hideo
1989-01-01
A computer code of groundwater flow in two-dimensional porous media based on the mixed finite element method was developed for accurate approximations of Darcy velocities in safety evaluation of radioactive waste disposal. The mixed finite element procedure solves for both the Darcy velocities and pressure heads simultaneously in the Darcy equation and continuity equation. Numerical results of a single well pumping at a constant rate in a uniform flow field showed that the mixed finite element method gives more accurate Darcy velocities nearly 50 % on average error than standard finite element method. (author)
Stochastic description of heterogeneities of permeability within groundwater flow models
International Nuclear Information System (INIS)
Cacas, M.C.; Lachassagne, P.; Ledoux, E.; Marsily, G. de
1991-01-01
In order to model radionuclide migration in the geosphere realistically at the field scale, the hydrogeologist needs to be able to simulate groundwater flow in heterogeneous media. Heterogeneity of the medium can be described using a stochastic approach, that affects the way in which a flow model is formulated. In this paper, we discuss the problems that we have encountered in modelling both continuous and fractured media. The stochastic approach leads to a methodology that enables local measurements of permeability to be integrated into a model which gives a good prediction of groundwater flow on a regional scale. 5 Figs.; 8 Refs
International Nuclear Information System (INIS)
Bae, D.S.; Kim, C.S.; Koh, Y.K.; Kim, K.S.; Song, M.Y.
1997-01-01
The prediction of groundwater flow affecting the migration of radionuclides is an important component of the performance assessment of radioactive waste disposal. Groundwater flow in fractured rock mass is controlled by fracture networks, transmissivity and hydraulic gradient. Furthermore the scale-dependent and anisotropic properties of hydraulic parameters are resulted mainly from irregular patterns of fracture system, which are very complex to evaluate properly with the current techniques available. For the purpose of characterizing a groundwater flow in fractured rock mass, the discrete fracture network (DFN) concept is available on the basis of assumptions of groundwater flowing only along fractures and flowpaths in rock mass formed by interconnected fractures. To increase the reliability of assessment in groundwater flow phenomena, numerical groundwater flow model and isotopic techniques were applied. Fracture mapping, borehole acoustic scanning were performed to identify conductive fractures in gneissic terrane. Tracer techniques, using deuterium, oxygen-18 and tritium were applied to evaluate the recharge area and groundwater residence time
Modeling of groundwater flow for Mujib aquifer, Jordan
Indian Academy of Sciences (India)
Jordan is an arid country with very limited water resources. ... groundwater flow model to simulate the behavior of the flow system under ... decision makers and planners in selecting optimum management schemes suitable for arid and semi- arid regions. 2. Methodology ..... This work was supported by the Jordan University.
International Nuclear Information System (INIS)
Kurosawa, Susumu; Nagasaki, Shinya; Tanaka, Satoru
2007-01-01
Theoretical study has been performed to clarify the ability of colloid release form the montmorillonite gel by the flowing groundwater. Evaluation of montmorillonite colloidal particles release from the bentonite buffer material is important for the performance assessment of radioactive waste disposal because the colloids may influence the radionuclide transport. In this study, the minimum groundwater flow rate required to tear off montmorillonite particles from surface of bentonite buffer was estimated from the shear stress on the gel front, which was calculated by the DLVO theory. The estimated shear force was converted to corresponding groundwater velocity by using Stoke's equation. The results indicated that groundwater velocity in a range of about 10 -5 to 10 -4 m/s would be necessary to release montmorillonite particles. This range is higher than the groundwater flow velocity found generally in deep geological media in Japan. This study suggests that the effect of montmorillonite particles release from the bentonite buffer on radionuclide transport is likely to be negligible in the performance assessment of high-level radioactive waste geological disposal. (author)
Climate reconstruction from borehole temperatures influenced by groundwater flow
Kurylyk, B.; Irvine, D. J.; Tang, W.; Carey, S. K.; Ferguson, G. A. G.; Beltrami, H.; Bense, V.; McKenzie, J. M.; Taniguchi, M.
2017-12-01
Borehole climatology offers advantages over other climate reconstruction methods because further calibration steps are not required and heat is a ubiquitous subsurface property that can be measured from terrestrial boreholes. The basic theory underlying borehole climatology is that past surface air temperature signals are reflected in the ground surface temperature history and archived in subsurface temperature-depth profiles. High frequency surface temperature signals are attenuated in the shallow subsurface, whereas low frequency signals can be propagated to great depths. A limitation of analytical techniques to reconstruct climate signals from temperature profiles is that they generally require that heat flow be limited to conduction. Advection due to groundwater flow can thermally `contaminate' boreholes and result in temperature profiles being rejected for regional climate reconstructions. Although groundwater flow and climate change can result in contrasting or superimposed thermal disturbances, groundwater flow will not typically remove climate change signals in a subsurface thermal profile. Thus, climate reconstruction is still possible in the presence of groundwater flow if heat advection is accommodated in the conceptual and mathematical models. In this study, we derive a new analytical solution for reconstructing surface temperature history from borehole thermal profiles influenced by vertical groundwater flow. The boundary condition for the solution is composed of any number of sequential `ramps', i.e. periods with linear warming or cooling rates, during the instrumented and pre-observational periods. The boundary condition generation and analytical temperature modeling is conducted in a simple computer program. The method is applied to reconstruct climate in Winnipeg, Canada and Tokyo, Japan using temperature profiles recorded in hydrogeologically active environments. The results demonstrate that thermal disturbances due to groundwater flow and climate
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.
An initial examination of tungsten geochemistry along groundwater flow paths
Dave, H. B.; Johannesson, K. H.
2008-12-01
Groundwater samples were collected along groundwater flow paths from the Upper Floridan (Florida), Carrizo Sand (Texas), and the Aquia (Maryland) aquifers and analyzed for tungsten (W) concentrations by high- resolution inductively couple plasma mass spectrometry. At each well head, groundwater samples were also analyzed for pH, specific conductance, temperature, alkalinity, dissolved oxygen (DO), oxidation-reduction potential (Eh), dissolved iron speciation, and dissolved sulfide [S(-II)] concentrations. Sediment samples from the Carrizo Sand and Aquia aquifers were also collected and subjected to sequential extractions to provide additional insights into the solid-phase speciation of W in these aquifers. Tungsten concentrations varied along the groundwater flow paths chiefly in response to changing pH, and to a lesser extent, variations in the redox conditions. For groundwater from the Carrizo Sand aquifer, W ranges between 3.64 and 1297 pmol/kg, exhibiting the lowest values proximal to the recharge zone. Tungsten concentrations progressively increase along the flow path, reaching 1297 pmol/kg in the sulfidic groundwaters located approximately 60 km downgradient from the recharge area. Tungsten is strongly correlated with S(-II) concentrations and pH in Carrizo groundwaters (r = 0.95 and 0.78, respectively). Within the Aquia aquifer, however, W generally occurs at lower concentrations than the Carrizo (14 to 184 pmol/kg; mean = 80 pmol/kg), and shows no systematic trends along the flow path (e.g., r = 0.08 and 0.4 for W vs. S(-II) and pH, respectively). Our data are consistent with the increase in W concentrations in Carrizo groundwaters reflecting, in part, pH-related desorption, which has been shown to be substantial for pH greater than 8. Moreover, because of the broad similarities in the chemistry of W and Mo, which forms thiomolybdates in sulfidic waters, we suggest that thiotungstate complexes may form in sulfidic groundwaters, thus partially explaining the
Groundwater flow in a coastal peatland and its influence on submarine groundwater discharge
Ptak, T.; Ibenthal, M.; Janssen, M.; Massmann, G.; Lenartz, B.
2017-12-01
Coastal peatlands are characterized by intense interactions between land and sea, comprising both a submarine discharge of fresh groundwater and inundations of the peatland with seawater. Nutrients and salts can influence the biogeochemical processes both in the shallow marine sediments and in the peatland. The determination of flow direction and quantity of groundwater flow are therefore elementary. Submarine groundwater discharge (SGD) has been reported from several locations in the Baltic. The objective of this study is to quantify the exchange of fresh and brackish water across the shoreline in a coastal peatland in Northeastern Germany, and to assess the influence of a peat layer extending into the Baltic Sea. Below the peatland, a shallow fine sand aquifer differs in depth and is limited downwards by glacial till. Water level and electrical conductivity (EC) are permanently measured in different depths at eight locations in the peatland. First results indicate a general groundwater flow direction towards the sea. Electrical conductivity measurements suggest different permeabilities within the peat layer, depending on its thickness and degradation. Near the beach, EC fluctuates partially during storm events due to seawater intrusion and reverse discharge afterwards. The groundwater flow will be verified with a 3D model considering varying thicknesses of the aquifer. Permanent water level and electrical conductivity readings, meteorological data and hydraulic conductivity from slug tests and grain size analysis are the base for the calibration of the numerical model.
A Method to Evaluate Groundwater flow system under the Seabed
Kohara, N.; Marui, A.
2011-12-01
/ fresh water interface (position of the submarine groundwater discharge) may appear on the seafloor. Moreover, neither the salinity concentration nor the groundwater age depends on depth. It is thought that it is because that the groundwater forms the complex flow situation through the change in a long-term groundwater flow system. The technology to understand the coastal groundwater flow consists of remote sensing, geographical features analysis, surface of the earth investigation, geophysical exploration, drilling survey, and indoor examination and the measurement. Integration of each technology is needed to interpret groundwater flow system because the one is to catch the local groundwater flow in the time series and another one is to catch the long-term and regional groundwater flow in the general situation. The purpose of this study is to review the previous research of coastal groundwater flow, and to integrate an applicable evaluation approach to understand this mechanism. In this presentation, the review of the research and case study using numerical simulation are introduced.
Determination of groundwater flow velocity by radon measurements
International Nuclear Information System (INIS)
Hohn, E.; von Gunten, H.R.
1990-01-01
The groundwater resources of glacio-fluvial perialpine valleys are recharged significantly by the infiltration from rivers. The groundwater residence times between rivers and wells should be known in groundwater management problems. Short residence times can be estimated using radon. Radon concentrations in rivers are usually very low. Upon filtration and movement of the water in the ground, radon is picked up and its concentration increases by 2-3 orders of magnitude according to radioactive growth laws. Residence times and flow velocities can be estimated from the increasing radon concentrations measured in groundwater sampling tubes at different distances from the river. Results obtained with this method agree with the results from experiments with artificial tracers
Heat and Groundwater Flow in the San Gabriel Mountains, California
Newman, A. A.; Becker, M.; Laton, W. R., Jr.
2017-12-01
Groundwater flow paths in mountainous terrain often vary widely in both time and space. Such systems remain difficult to characterize due to fracture-dominated flow paths, high topographic relief, and sparse hydrologic data. We develop a hydrogeologic conceptual model of the Western San Gabriel Mountains in Southern California based on geophysical, thermal, and hydraulic head data. Boreholes are located along the San Gabriel Fault Zone (SGFZ) and cover a wide range of elevations to capture the heterogeneity of the hydrogeologic system. Long term (2016-2017) monitoring of temperature and hydraulic head was carried out in four shallow (300-600m depth) boreholes within the study area using fiber-optic distributed temperature sensing (DTS). Borehole temperature profiles were used to assess the regional groundwater flow system and local flows in fractures intersecting the borehole. DTS temperature profiles were compared with available borehole geophysical logs and head measurements collected with grouted vibrating wire pressure transducers (VWPT). Spatial and temporal variations in borehole temperature profiles suggest that advective heat transfer due to fluid flow affected the subsurface thermal regime. Thermal evidence of groundwater recharge and/or discharge and flow through discrete fractures was found in all four boreholes. Analysis of temporal changes to the flow system in response to seasonal and drilling-induced hydraulic forcing was useful in reducing ambiguities in noisy datasets and estimating interborehole relationships. Acoustic televiewer logs indicate fractures were primarily concentrated in densely fractured intervals, and only a minor decrease of fracture density was observed with depth. Anomalously high hydraulic gradients across the SGFZ suggest that the feature is a potential barrier to lateral flow. However, transient thermal anomalies consistent with groundwater flow within the SGFZ indicate this feature may be a potential conduit to vertical flow
Application of artificial radioactive tracers for groundwater flow
International Nuclear Information System (INIS)
Hamza, M.S.; Aly, A.I.M.; Swailem, F.M.; Nada, A.A.; Awad, M.A.
1989-01-01
In this work, the groundwater velocity was estimated by applying radioactive tracer techniques: the single well and the multiple well methods. In the first single well method, radioactive iodine-131 was injected in the well and the radioactivity was monitored with time. The groundwater flow was estimated as a function of the concentration dilution factor of the tracer taking into consideration the permeability of the filter screen and the aquifer. The second method (the multiple well technique) is based on direct measuring of the period of time the tracer needs to disperse from the injection well to one of receptor well arranged in a circle around the injection. The latter method was found to be more accurate and reliable and has also the advantage of determining the groundwater velocity and direction of flow as well. The limitations of the single well technique are discussed and a detailed comparison between single and multi-well techniques is given
Groundwater flow and sorption processes in fractured rocks (I)
Energy Technology Data Exchange (ETDEWEB)
Kim, Won Young; Woo, Nam Chul; Yum, Byoung Woo; Choi, Young Sub; Chae, Byoung Kon; Kim, Jung Yul; Kim, Yoo Sung; Hyun, Hye Ja; Lee, Kil Yong; Lee, Seung Gu; Youn, Youn Yul; Choon, Sang Ki [Korea Institute of Geology Mining and Materials, Taejon (Korea, Republic of)
1996-12-01
This study is objected to characterize groundwater flow and sorption processes of the contaminants (ground-water solutes) along the fractured crystalline rocks in Korea. Considering that crystalline rock mass is an essential condition for using underground space cannot be overemphasized the significance of the characterizing fractured crystalline rocks. the behavior of the groundwater contaminants is studied in related to the subsurface structure, and eventually a quantitative technique will be developed to evaluate the impacts of the contaminants on the subsurface environments. The study has been carried at the Samkwang mine area in the Chung-Nam Province. The site has Pre-Cambrian crystalline gneiss as a bedrock and the groundwater flow system through the bedrock fractures seemed to be understandable with the study on the subsurface geologic structure through the mining tunnels. Borehole tests included core logging, televiewer logging, constant pressure fixed interval length tests and tracer tests. The results is summarized as follows; 1) To determine the hydraulic parameters of the fractured rock, the transient flow analysis produce better results than the steady - state flow analysis. 2) Based on the relationship between fracture distribution and transmissivities measured, the shallow part of the system could be considered as a porous and continuous medium due to the well developed fractures and weathering. However, the deeper part shows flow characteristics of the fracture dominant system, satisfying the assumptions of the Cubic law. 3) Transmissivities from the FIL test were averaged to be 6.12 x 10{sup -7}{sub m}{sup 2}{sub /s}. 4) Tracer tests result indicates groundwater flow in the study area is controlled by the connection, extension and geometry of fractures in the bedrock. 5) Hydraulic conductivity of the tracer-test interval was in maximum of 7.2 x 10{sup -6}{sub m/sec}, and the effective porosity of 1.8 %. 6) Composition of the groundwater varies
Detect groundwater flowing from riverbed using a drone
Kato, Kenji; Takemon, Yasuhiro
2017-04-01
Estimate the direct flow of groundwater to river is an important step in understanding of hydrodynamics in river system. Function of groundwater in river system does not limit to the mass of water. Continuous supply with thermally stable water from riverbed produces a space with unique condition, which provides various functions for organisms inhabiting in river as a shelter avoiding large shift of temperature, or to maintain productivity for small scale ecosystem by supplying nutrient rich groundwater if it gushes out from the riverbed in a deep pool of river. This may contribute to biodiversity of river system. Such function of groundwater is more significant for rivers run in island and in mountain zone. To evaluate the function of groundwater flowing from riverbed we first try to find such site by using a drone equipped with a sensitive thermo-camera to detect water surface temperature. In the examined area temperature of the groundwater doesn't change much throughout a year at around 15 to 16 °C, while surface temperature of the examined river fluctuates from below 10 °C to over 25 °C throughout seasons. By using this difference in temperature between groundwater and river water we tried to find site where groundwater comes out from the riverbed. Obviously winter when surface temperature becomes below 10 °C is an appropriate season to find groundwater as it comes up to the surface of river with depth ranging from 1 to 3 m. Trial flight surveys of drone were conducted in Kano-river in Izu Peninsula located at southern foot of Mt. Fuji in central Japan. Employed drone was Inspire1 (DJI, China) equipped with a Thermal camera (Zenmuse XT ZXTA 19 FP, FLIR, USA) and operated by Kazuhide Juta (KELEK Co. Ltd., Japan) and Mitsuhiro Komiya (TAM.Co.,LTD). In contrast to the former cases with employing airplane for taking aerial photograph, drone takes photo while flying at a low-altitude. When it flies at 40m above the water surface of river, resolution is at an
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)
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
Investigation of groundwater flow potential in Makurdi, North Central ...
African Journals Online (AJOL)
hp
Department of Physics and Astronomy, University of Nigeria, Nsukka, Nigeria. Received 6 August, 2015; ... order to study the groundwater flow potential in Makurdi, north central Nigeria. This was done in thirty .... 600 m above sea level. The drainage consists ..... engineering Studies: A Practical Guide to 2D and 3D Surveys.
Ambient groundwater flow diminishes nitrogen cycling in streams
Azizian, M.; Grant, S. B.; Rippy, M.; Detwiler, R. L.; Boano, F.; Cook, P. L. M.
2017-12-01
Modeling and experimental studies demonstrate that ambient groundwater reduces hyporheic exchange, but the implications of this observation for stream N-cycling is not yet clear. We utilized a simple process-based model (the Pumping and Streamline Segregation or PASS model) to evaluate N- cycling over two scales of hyporheic exchange (fluvial ripples and riffle-pool sequences), ten ambient groundwater and stream flow scenarios (five gaining and losing conditions and two stream discharges), and three biogeochemical settings (identified based on a principal component analysis of previously published measurements in streams throughout the United States). Model-data comparisons indicate that our model provides realistic estimates for direct denitrification of stream nitrate, but overpredicts nitrification and coupled nitrification-denitrification. Riffle-pool sequences are responsible for most of the N-processing, despite the fact that fluvial ripples generate 3-11 times more hyporheic exchange flux. Across all scenarios, hyporheic exchange flux and the Damkohler Number emerge as primary controls on stream N-cycling; the former regulates trafficking of nutrients and oxygen across the sediment-water interface, while the latter quantifies the relative rates of organic carbon mineralization and advective transport in streambed sediments. Vertical groundwater flux modulates both of these master variables in ways that tend to diminish stream N-cycling. Thus, anthropogenic perturbations of ambient groundwater flows (e.g., by urbanization, agricultural activities, groundwater mining, and/or climate change) may compromise some of the key ecosystem services provided by streams.
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.)
International Nuclear Information System (INIS)
Ohyama, Takuya; Saegusa, Hiromitsu; Onoe, Hironori
2005-05-01
Japan Nuclear Cycle Development Institute 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 environment 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 groundwater flow system immediately surrounding the MIU construction site. The MIU project is being conducted using a multiphase, iterative approach. In this study, the hydrogeological modeling and groundwater flow analysis of the 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 Step 1 in site scale of the MIU project. As a result of the study, head distribution to set boundary conditions for groundwater flow analysis on the site scale model could be obtained. (author)
Groundwater flow and mixing in a wetland–stream system
DEFF Research Database (Denmark)
Karan, Sachin; Engesgaard, Peter Knudegaard; Zibar, Majken Caroline Looms
2013-01-01
steady-state groundwater model that was calibrated against average head observations. The model results were tested against groundwater fluxes determined from streambed temperature measurements. Discharge varied up to one order of magnitude across the stream and the model was successful in capturing...... in the top of the aquifer and immediately underneath the streambed no NO3- was detected deeper within the aquifer. An inverse relationship between NO3- and SO42- suggests that pyrite oxidation takes place in the deeper parts of the aquifer. Simulated flow path lines showed very different origins for deeper...
Sources and flow of north Canterbury Plains groundwater, New Zealand
International Nuclear Information System (INIS)
Taylor, C.B.; Brown, L.J.; Stewart, M.K.; Brailsford, G.W.; Wilson, D.D.; Burden, R.J.
1989-01-01
Geological, hydrological, isotope (tritium and 18 O) and chemical evidence is interpreted to give a mutually consistent picture of the recharge sources and flow patterns of the important groundwater resource in the deep Quaternary deposits of the Canterbury Plains between Selwyn R. and Ashley R. The study period for tritium measurements extends over 27 years, encompassing the peak and decline of thermonuclear tritium fallout in this region. Major rivers emerging from mountain catchments to the west of the Plains are depleted in 18 O relative to average low-level precipitation. Most of the groundwater is river-recharged, but some areas with significant local precipitation recharge are clearly identified by 18 O and chemical concentrations. Artesian groundwater underlying Christchurch ascends from deeper aquifers into the shallowest aquifer via gaps in the confining layers; much of this flow is induced by withdrawal. The Christchurch aquifers are recharged by infiltration from Waimakariri R. in its central Plains reaches, and the resulting flow regime is E- and SE-directed; satisfactory water quality of the deeper Christchurch aquifer appears to be guaranteed for the future provided the river can be maintained in its present condition. Shallow groundwater, and water recharged to depth by other rivers, irrigation and local precipitation on the unconfined western areas of the Plains, are more susceptible to agricultural and other pollutants; none of this water is encountered in the deeper aquifers under Christchurch. (author). 15 refs., 12 figs
Groundwater availability as constrained by hydrogeology and environmental flows.
Watson, Katelyn A; Mayer, Alex S; Reeves, Howard W
2014-01-01
Groundwater pumping from aquifers in hydraulic connection with nearby streams has the potential to cause adverse impacts by decreasing flows to levels below those necessary to maintain aquatic ecosystems. The recent passage of the Great Lakes-St. Lawrence River Basin Water Resources Compact has brought attention to this issue in the Great Lakes region. In particular, the legislation requires the Great Lakes states to enact measures for limiting water withdrawals that can cause adverse ecosystem impacts. This study explores how both hydrogeologic and environmental flow limitations may constrain groundwater availability in the Great Lakes Basin. A methodology for calculating maximum allowable pumping rates is presented. Groundwater availability across the basin may be constrained by a combination of hydrogeologic yield and environmental flow limitations varying over both local and regional scales. The results are sensitive to factors such as pumping time, regional and local hydrogeology, streambed conductance, and streamflow depletion limits. Understanding how these restrictions constrain groundwater usage and which hydrogeologic characteristics and spatial variables have the most influence on potential streamflow depletions has important water resources policy and management implications. © 2013, National Ground Water Association.
The flow equation approach to many-particle systems
Kehrein, Stefan; Fujimori, A; Varma, C; Steiner, F
2006-01-01
This self-contained monograph addresses the flow equation approach to many-particle systems. The flow equation approach consists of a sequence of infinitesimal unitary transformations and is conceptually similar to renormalization and scaling methods. Flow equations provide a framework for analyzing Hamiltonian systems where these conventional many-body techniques fail. The text first discusses the general ideas and concepts of the flow equation method. In a second part these concepts are illustrated with various applications in condensed matter theory including strong-coupling problems and non-equilibrium systems. The monograph is accessible to readers familiar with graduate- level solid-state theory.
Microbes Characteristics in Groundwater Flow System in Mountainous Area
Yamamoto, Chisato; Tsujimura, Maki; Kato, Kenji; Sakakibara, Koichi; Ogawa, Mahiro; Sugiyama, Ayumi; Nagaosa, Kazuyo
2017-04-01
We focus on a possibility of microbes as a tracer for groundwater flow investigation. Some previous papers showed that the total number of prokaryotes in groundwater has correlation with depth and geology (Parkes et al., 1994; Griebler et al., 2009; Kato et al., 2012). However, there are few studies investigating both microbe characteristics and groundwater flow system. Therefore, we investigated a relationship between the total number of prokaryotes and age of spring water and groundwater. Intensive field survey was conducted at four mountainous areas, namely Mt. Fuji (volcano), a headwater at Mt. Setohachi, a headwater at River Oi and a headwater at River Nagano underlain by volcanic lava at Mt. Fuji, granite at Mt. Setohachi and sedimentary rock at River Oi and River Nagano. We collected totally 40 spring water/ groundwater samples in these mountainous areas in October 2015, August, October and November 2016 and analyzed concentration of inorganic ions, the stable isotopes of oxygen - 18, deuterium, CFCs and SF6. Also, we counted prokaryotic cells under the epifluorescence microscopy after fixation and filteration. The total number of prokaryotes in the spring water/ groundwater ranged from 1.0×102 to 7.0×103cells mL-1 at the Mt. Fuji, 1.3×104 to 2.7×105cells mL-1 at Mt. Setohachi, 3.1×104cells mL-1 at River Oi and 1.8×105 to 3.2×106cells mL-1 at River Nagano. The SF6 age of the spring water/ groundwater ranged from 8 to 64 years at Mt. Fuji, 2 to 32.5 years at Mt. Setohachi, 2.5 years at River Oi and 15 to 16 years at River Nagano. The total number of prokaryotes showed a clear negative correlation with residence time of spring water/ groundwater in all regions. Especially the prokaryotes number increased in the order of 102 cells mL-1 with decreasing of residence time in approximately 10 years in the groundwater and spring water with the age less than 15 years.
Incorporating groundwater flow into the WEPP model
William Elliot; Erin Brooks; Tim Link; Sue Miller
2010-01-01
The water erosion prediction project (WEPP) model is a physically-based hydrology and erosion model. In recent years, the hydrology prediction within the model has been improved for forest watershed modeling by incorporating shallow lateral flow into watershed runoff prediction. This has greatly improved WEPP's hydrologic performance on small watersheds with...
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
Tracer techniques for determination of groundwater flow parameters
International Nuclear Information System (INIS)
Drost, W.; Klotz, D.
1988-05-01
The most common one-borehole and multiple borehole methods using tracers for the direct determination of the groundwater flow parameters (velocity of flow, flow direction) and for the indirect determination of characteristic quantities of the aquifer (effective porosity, dispersivity, transmissivity) are presented methodically and their value is documented by practical examples. Especially, the properties of and measuring technique with suitable tracers are considered (e.g. T, Na-24, Cr-51, Co-58, Co-60, Br-82, Tc-99, I-125, I-131, Au-198). (orig./HP) [de
Symmetries of the Euler compressible flow equations for general equation of state
Energy Technology Data Exchange (ETDEWEB)
Boyd, Zachary M. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Ramsey, Scott D. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Baty, Roy S. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
2015-10-15
The Euler compressible flow equations exhibit different Lie symmetries depending on the equation of state (EOS) of the medium in which the flow occurs. This means that, in general, different types of similarity solution will be available in different flow media. We present a comprehensive classification of all EOS’s to which the Euler equations apply, based on the Lie symmetries admitted by the corresponding flow equations, restricting to the case of 1-D planar, cylindrical, or spherical geometry. The results are conveniently summarized in tables. This analysis also clarifies past work by Axford and Ovsiannikov on symmetry classification.
Numerical analysis of thermal response tests with a groundwater flow and heat transfer model
Energy Technology Data Exchange (ETDEWEB)
Raymond, J.; Therrien, R. [Departement de Geologie et de Genie Ggeologique, Universite Laval, 1065 avenue de la medecine, Quebec (Qc) G1V 0A6 (Canada); Gosselin, L. [Departement de Genie Mecanique, Universite Laval, 1065 avenue de la medecine, Quebec (Qc) G1V 0A6 (Canada); Lefebvre, R. [Institut National de la Recherche Scientifique, Centre Eau Terre Environnement, 490 de la Couronne, Quebec (Qc) G1K 9A9 (Canada)
2011-01-15
The Kelvin line-source equation, used to analyze thermal response tests, describes conductive heat transfer in a homogeneous medium with a constant temperature at infinite boundaries. The equation is based on assumptions that are valid for most ground-coupled heat pump environments with the exception of geological settings where there is significant groundwater flow, heterogeneous distribution of subsurface properties, a high geothermal gradient or significant atmospheric temperature variations. To address these specific cases, an alternative method to analyze thermal response tests was developed. The method consists in estimating parameters by reproducing the output temperature signal recorded during a test with a numerical groundwater flow and heat transfer model. The input temperature signal is specified at the entrance of the ground heat exchanger, where flow and heat transfer are computed in 2D planes representing piping and whose contributions are added to the 3D porous medium. Results obtained with this method are compared to those of the line-source model for a test performed under standard conditions. A second test conducted in waste rock at the South Dump of the Doyon Mine, where conditions deviate from the line-source assumptions, is analyzed with the numerical model. The numerical model improves the representation of the physical processes involved during a thermal response test compared to the line-source equation, without a significant increase in computational time. (author)
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
Climate proxy data as groundwater tracers in regional flow systems
Clark, J. F.; Morrissey, S. K.; Stute, M.
2008-05-01
The isotopic and chemical signatures of groundwater reflect local climate conditions. By systematically analyzing groundwater and determining their hydrologic setting, records of past climates can be constructed. Because of their chemistries and relatively uncomplicated source functions, dissolved noble gases have yielded reliable records of continental temperatures for the last 30,000 to 50,000 years. Variations in the stable isotope compositions of groundwater due to long term climate changes have also been documented over these time scales. Because glacial - interglacial climate changes are relatively well known, these climate proxies can be used as "stratigraphic" markers within flow systems and used to distinguish groundwaters that have recharged during the Holocene from those recharged during the last glacial period, important time scales for distinguishing regional and local flow systems in many aquifers. In southern Georgia, the climate proxy tracers were able to identify leakage from surface aquifers into the Upper Floridan aquifer in areas previously thought to be confined. In south Florida, the transition between Holocene and glacial signatures in the Upper Floridan aquifer occurs mid-way between the recharge area and Lake Okeechobee. Down gradient of the lake, the proxies are uniform, indicating recharge during the last glacial period. Furthermore, there is no evidence for leakage from the shallow aquifers into the Upper Floridan. In the Lower Floridan, the climate proxies indicate that the saline water entered the aquifer after sea level rose to its present level.
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)
International Nuclear Information System (INIS)
Thomas, J.M.; Benedict, F.C. Jr.; Rose, T.P.; Hershey, R.L.; Paces, J.B.; Peterman, Z.E.; Farnham, I.M.; Johannesson, K.H.; Singh, A.K.; Stetzenbach, K.J.; Hudson, G.B.; Kenneally, J.M.; Eaton, G.F.; Smith, D.K.
2003-01-01
This report summarizes the findings of a geochemical investigation of the Pahute Mesa-Oasis Valley groundwater flow system in southwestern Nevada. It is intended to provide geochemical data and interpretations in support of flow and contaminant transport modeling for the Western and Central Pahute Mesa Corrective Action Units
Peters, E.; Lanen, van H.A.J.
2005-01-01
A new filter to separate base flow from streamflow has developed that uses observed groundwater levels. To relate the base flow to the observed groundwater levels, a non-linear relation was used. This relation is suitable for unconfined aquifers with deep groundwater levels that do not respond to
Constitutive equations for two-phase flows
International Nuclear Information System (INIS)
Boure, J.A.
1974-12-01
The mathematical model of a system of fluids consists of several kinds of equations complemented by boundary and initial conditions. The first kind equations result from the application to the system, of the fundamental conservation laws (mass, momentum, energy). The second kind equations characterize the fluid itself, i.e. its intrinsic properties and in particular its mechanical and thermodynamical behavior. They are the mathematical model of the particular fluid under consideration, the laws they expressed are so called the constitutive equations of the fluid. In practice the constitutive equations cannot be fully stated without reference to the conservation laws. Two classes of model have been distinguished: mixture model and two-fluid models. In mixture models, the mixture is considered as a single fluid. Besides the usual friction factor and heat transfer correlations, a single constitutive law is necessary. In diffusion models, the mixture equation of state is replaced by the phasic equations of state and by three consitutive laws, for phase change mass transfer, drift velocity and thermal non-equilibrium respectively. In the two-fluid models, the two phases are considered separately; two phasic equations of state, two friction factor correlations, two heat transfer correlations and four constitutive laws are included [fr
Exact RG flow equations and quantum gravity
de Alwis, S. P.
2018-03-01
We discuss the different forms of the functional RG equation and their relation to each other. In particular we suggest a generalized background field version that is close in spirit to the Polchinski equation as an alternative to the Wetterich equation to study Weinberg's asymptotic safety program for defining quantum gravity, and argue that the former is better suited for this purpose. Using the heat kernel expansion and proper time regularization we find evidence in support of this program in agreement with previous work.
Coupled heat and groundwater flow in porous rock
International Nuclear Information System (INIS)
Rae, J.; Robinson, P.C.; Wickens, L.M.
1983-01-01
There are a number of technical areas where coupled heat and flow problems occur for water in porous rock. The area of most interest to the authors has been the possible disposal underground of high-level radioactive waste. High-level waste can emit enough heat to drive significant flows by buoyancy effects and groundwater flow is expected to be the chief transport process for solute leached from such a repository. The possible disposal of radioactive waste under the seabed raises many similar questions and needs similar techniques to find answers. Other areas where related questions arise are the storage and retrieval of hot water in underground reservoirs, the attempts to extract useful geothermal energy by pumping water into fracture systems in hot rock and in certain thermal techniques for persuading oil to flow in tight reservoirs. The authors address questions in a rather general way and give examples which lie more in the area of waste disposal
Regional-to-site scale groundwater flow in Romuvaara
Energy Technology Data Exchange (ETDEWEB)
Kattilakoski, E.; Koskinen, L. [VTT Energy, Espoo (Finland)
1999-04-01
The work describing numerical groundwater flow modelling at the Romuvaara site serves as a background report for the safety assessment TILA-99. The site scale can roughly be taken as the scale of detailed borehole investigations, which have probed the bedrock of Romuvaara over about 2 km{sup 2} large and 1 km deep volume. The site model in this work covers an area of about 12 km{sup 2}. The depth of the model is 2200 m. The site scale flow modelling produced characteristics of the deep groundwater flow and evaluated the impact of a spent fuel repository on the natural groundwater flow conditions. It treated the hydraulic gradient in the intact rock between the repository and the fracture zone nearest to it (about 50 m off) for the block scale model, which describes the groundwater flow on the repository scale. The result quantities were the hydraulic head h (as the base quantity) and its gradient in selected cross sections and fracture zones, the flow rates around the repository, flow paths and discharge areas of the water from the repository. Two repository layouts were discussed. The numerical simulations were performed with the FEFTRA code based on the porous medium concept and the finite element method. The regional model with a no-flow boundary condition at the bottom and on the lateral edges was firstly used to confirm the hydraulic head boundary condition on the lateral edges of an interior site model (having a no-flow boundary condition at the bottom). The groundwater table was used as the hydraulic head boundary condition at the surface of each model. Both the conductivity of the bedrock (modeled with three-dimensional elements) and the transmissivities of the fracture zones (described with two-dimensional elements in the three-dimensional mesh) decreased as a function of the depth. All the results were derived from the site model. The range of variation of the hydraulic gradient immediately outside the repository was studied in the direction of the flow
Scale problems in assessment of hydrogeological parameters of groundwater flow models
Nawalany, Marek; Sinicyn, Grzegorz
2015-09-01
An overview is presented of scale problems in groundwater flow, with emphasis on upscaling of hydraulic conductivity, being a brief summary of the conventional upscaling approach with some attention paid to recently emerged approaches. The focus is on essential aspects which may be an advantage in comparison to the occasionally extremely extensive summaries presented in the literature. In the present paper the concept of scale is introduced as an indispensable part of system analysis applied to hydrogeology. The concept is illustrated with a simple hydrogeological system for which definitions of four major ingredients of scale are presented: (i) spatial extent and geometry of hydrogeological system, (ii) spatial continuity and granularity of both natural and man-made objects within the system, (iii) duration of the system and (iv) continuity/granularity of natural and man-related variables of groundwater flow system. Scales used in hydrogeology are categorised into five classes: micro-scale - scale of pores, meso-scale - scale of laboratory sample, macro-scale - scale of typical blocks in numerical models of groundwater flow, local-scale - scale of an aquifer/aquitard and regional-scale - scale of series of aquifers and aquitards. Variables, parameters and groundwater flow equations for the three lowest scales, i.e., pore-scale, sample-scale and (numerical) block-scale, are discussed in detail, with the aim to justify physically deterministic procedures of upscaling from finer to coarser scales (stochastic issues of upscaling are not discussed here). Since the procedure of transition from sample-scale to block-scale is physically well based, it is a good candidate for upscaling block-scale models to local-scale models and likewise for upscaling local-scale models to regional-scale models. Also the latest results in downscaling from block-scale to sample scale are briefly referred to.
Scale problems in assessment of hydrogeological parameters of groundwater flow models
Directory of Open Access Journals (Sweden)
Nawalany Marek
2015-09-01
Full Text Available An overview is presented of scale problems in groundwater flow, with emphasis on upscaling of hydraulic conductivity, being a brief summary of the conventional upscaling approach with some attention paid to recently emerged approaches. The focus is on essential aspects which may be an advantage in comparison to the occasionally extremely extensive summaries presented in the literature. In the present paper the concept of scale is introduced as an indispensable part of system analysis applied to hydrogeology. The concept is illustrated with a simple hydrogeological system for which definitions of four major ingredients of scale are presented: (i spatial extent and geometry of hydrogeological system, (ii spatial continuity and granularity of both natural and man-made objects within the system, (iii duration of the system and (iv continuity/granularity of natural and man-related variables of groundwater flow system. Scales used in hydrogeology are categorised into five classes: micro-scale – scale of pores, meso-scale – scale of laboratory sample, macro-scale – scale of typical blocks in numerical models of groundwater flow, local-scale – scale of an aquifer/aquitard and regional-scale – scale of series of aquifers and aquitards. Variables, parameters and groundwater flow equations for the three lowest scales, i.e., pore-scale, sample-scale and (numerical block-scale, are discussed in detail, with the aim to justify physically deterministic procedures of upscaling from finer to coarser scales (stochastic issues of upscaling are not discussed here. Since the procedure of transition from sample-scale to block-scale is physically well based, it is a good candidate for upscaling block-scale models to local-scale models and likewise for upscaling local-scale models to regional-scale models. Also the latest results in downscaling from block-scale to sample scale are briefly referred to.
Macroscopic balance equations for two-phase flow models
International Nuclear Information System (INIS)
Hughes, E.D.
1979-01-01
The macroscopic, or overall, balance equations of mass, momentum, and energy are derived for a two-fluid model of two-phase flows in complex geometries. These equations provide a base for investigating methods of incorporating improved analysis methods into computer programs, such as RETRAN, which are used for transient and steady-state thermal-hydraulic analyses of nuclear steam supply systems. The equations are derived in a very general manner so that three-dimensional, compressible flows can be analysed. The equations obtained supplement the various partial differential equation two-fluid models of two-phase flow which have recently appeared in the literature. The primary objective of the investigation is the macroscopic balance equations. (Auth.)
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.
Radioactive Seepage through Groundwater Flow from the Uranium Mines, Namibia
Directory of Open Access Journals (Sweden)
Tamiru Abiye
2017-02-01
Full Text Available The study focused on the seepage of uranium from unlined tailing dams into the alluvial aquifer in the Gawib River floodplain in Namibia where the region solely relies on groundwater for its economic activities as a result of arid climatic condition. The study reviewed previous works besides water sample collection and analyses for major ions, metals and environmental isotopes in addition to field tests on physico-chemical parameters (pH, Electrical Conductivity, Redox and T. Estimation of seepage velocity (true velocity of groundwater flow has been conducted in order to understand the extent of radioactive plume transport. The hydrochemistry, stable isotopes and tritium results show that there is uranium contamination from the unlined uranium tailings in the Gawib shallow aquifer system which suggests high permeability of the alluvial aquifer facilitating groundwater flow in the arid region. The radioactive contaminants could spread into the deeper aquifer system through the major structures such as joints and faults. The contamination plume could also spread downstream into the Swakop River unless serious interventions are employed. There is also a very high risk of the plume to reach the Atlantic Ocean through seasonal flash floods that occurs in the area.
International Nuclear Information System (INIS)
Woerman, Anders; Sjoegren, Bjoern; Marklund, Lars
2004-12-01
This report describes a data-base that covers entire Sweden with regard to various geographical parameters with implications to simulation of groundwater circulation on a regional and continental scale. The data-base include topography, stream network properties, and-use and water chemistry for limited areas. Furthermore, the report describes a computational (finite difference) code that solves the continuum equation for laminar, stationary and isotropic groundwater flow. The formulation accounts for a free groundwater surface except where the groundwater recharge into the stream network and lake bottoms. The theoretical background of the model is provided and the codes are described. The report also contain a simple user manual in a Matlab environment and provides and example calculation for the Forsmark area, Uppland, Sweden.
Simulation of the regional groundwater-flow system of the Menominee Indian Reservation, Wisconsin
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.
From groundwater baselines to numerical groundwater flow modelling for the Milan metropolitan area
Crosta, Giovanni B.; Frattini, Paolo; Peretti, Lidia; Villa, Federica; Gorla, Maurizio
2015-04-01
allow for the groundwater flow and transport modeling at the large scale and could be successively linked to some more site-specific transport multi-reactive models focused on the modeling of some specific contaminants.
The 2016 groundwater flow model for Dane County, Wisconsin
Parsen, Michael J.; Bradbury, Kenneth R.; Hunt, Randall J.; Feinstein, Daniel T.
2016-01-01
A new groundwater flow model for Dane County, Wisconsin, replaces an earlier model developed in the 1990s by the Wisconsin Geological and Natural History Survey (WGNHS) and the U.S. Geological Survey (USGS). This modeling study was conducted cooperatively by the WGNHS and the USGS with funding from the Capital Area Regional Planning Commission (CARPC). Although the overall conceptual model of the groundwater system remains largely unchanged, the incorporation of newly acquired high-quality datasets, recent research findings, and improved modeling and calibration techniques have led to the development of a more detailed and sophisticated model representation of the groundwater system. The new model is three-dimensional and transient, and conceptualizes the county’s hydrogeology as a 12-layer system including all major unlithified and bedrock hydrostratigraphic units and two high-conductivity horizontal fracture zones. Beginning from the surface down, the model represents the unlithified deposits as two distinct model layers (1 and 2). A single layer (3) simulates the Ordovician sandstone and dolomite of the Sinnipee, Ancell, and Prairie du Chien Groups. Sandstone of the Jordan Formation (layer 4) and silty dolostone of the St. Lawrence Formation (layer 5) each comprise separate model layers. The underlying glauconitic sandstone of the Tunnel City Group makes up three distinct layers: an upper aquifer (layer 6), a fracture feature (layer 7), and a lower aquifer (layer 8). The fracture layer represents a network of horizontal bedding-plane fractures that serve as a preferential pathway for groundwater flow. The model simulates the sandstone of the Wonewoc Formation as an upper aquifer (layer 9) with a bedding-plane fracture feature (layer 10) at its base. The Eau Claire aquitard (layer 11) includes shale beds within the upper portion of the Eau Claire Formation. This layer, along with overlying bedrock units, is mostly absent in the preglacially eroded valleys along
Groundwater flow modelling of the excavation and operational phases - Laxemar
Energy Technology Data Exchange (ETDEWEB)
Svensson, Urban (Computer-aided Fluid Engineering AB, Lyckeby (Sweden)); Rhen, Ingvar (SWECO Environment AB, Falun (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 modelling study reported here presents calculated inflow rates, drawdown of the groundwater table and upconing of deep saline water for different levels of grouting efficiency during the excavation and operational phases of a final repository at Laxemar. The inflow calculations were accompanied by a sensitivity study, which among other matters handled the impact of different deposition hole rejection criteria. The report also presents tentative modelling results for the duration of the saturation phase, which starts once the used parts of the repository are being backfilled
Documentation for the MODFLOW 6 Groundwater Flow Model
Langevin, Christian D.; Hughes, Joseph D.; Banta, Edward R.; Niswonger, Richard G.; Panday, Sorab; Provost, Alden M.
2017-08-10
This report documents the Groundwater Flow (GWF) Model for a new version of MODFLOW called MODFLOW 6. The GWF Model for MODFLOW 6 is based on a generalized control-volume ﬁnite-difference approach in which a cell can be hydraulically connected to any number of surrounding cells. Users can deﬁne the model grid using one of three discretization packages, including (1) a structured discretization package for deﬁning regular MODFLOW grids consisting of layers, rows, and columns, (2) a discretization by vertices package for deﬁning layered unstructured grids consisting of layers and cells, and (3) a general unstructured discretization package for deﬁning ﬂexible grids comprised of cells and their connection properties. For layered grids, a new capability is available for removing thin cells and vertically connecting cells overlying and underlying the thin cells. For complex problems involving water-table conditions, an optional Newton-Raphson formulation, based on the formulations in MODFLOW-NWT and MODFLOW-USG, can be activated. Use of the Newton-Raphson formulation will often improve model convergence and allow solutions to be obtained for difﬁcult problems that cannot be solved using the traditional wetting and drying approach. The GWF Model is divided into “packages,” as was done in previous MODFLOW versions. A package is the part of the model that deals with a single aspect of simulation. Packages included with the GWF Model include those related to internal calculations of groundwater ﬂow (discretization, initial conditions, hydraulic conductance, and storage), stress packages (constant heads, wells, recharge, rivers, general head boundaries, drains, and evapotranspiration), and advanced stress packages (streamﬂow routing, lakes, multi-aquifer wells, and unsaturated zone ﬂow). An additional package is also available for moving water available in one package into the individual features of the advanced stress packages. The GWF Model
A correction on coastal heads for groundwater flow models.
Lu, Chunhui; Werner, Adrian D; Simmons, Craig T; Luo, Jian
2015-01-01
We introduce a simple correction to coastal heads for constant-density groundwater flow models that contain a coastal boundary, based on previous analytical solutions for interface flow. The results demonstrate that accurate discharge to the sea in confined aquifers can be obtained by direct application of Darcy's law (for constant-density flow) if the coastal heads are corrected to ((α + 1)/α)hs - B/2α, in which hs is the mean sea level above the aquifer base, B is the aquifer thickness, and α is the density factor. For unconfined aquifers, the coastal head should be assigned the value hs1+α/α. The accuracy of using these corrections is demonstrated by consistency between constant-density Darcy's solution and variable-density flow numerical simulations. The errors introduced by adopting two previous approaches (i.e., no correction and using the equivalent fresh water head at the middle position of the aquifer to represent the hydraulic head at the coastal boundary) are evaluated. Sensitivity analysis shows that errors in discharge to the sea could be larger than 100% for typical coastal aquifer parameter ranges. The location of observation wells relative to the toe is a key factor controlling the estimation error, as it determines the relative aquifer length of constant-density flow relative to variable-density flow. The coastal head correction method introduced in this study facilitates the rapid and accurate estimation of the fresh water flux from a given hydraulic head measurement and allows for an improved representation of the coastal boundary condition in regional constant-density groundwater flow models. © 2014, National Ground Water Association.
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
Ahmad, Zulfiqar; Ashraf, Arshad; Fryar, Alan; Akhter, Gulraiz
2011-02-01
The integration of the Geographic Information System (GIS) with groundwater modeling and satellite remote sensing capabilities has provided an efficient way of analyzing and monitoring groundwater behavior and its associated land conditions. A 3-dimensional finite element model (Feflow) has been used for regional groundwater flow modeling of Upper Chaj Doab in Indus Basin, Pakistan. The approach of using GIS techniques that partially fulfill the data requirements and define the parameters of existing hydrologic models was adopted. The numerical groundwater flow model is developed to configure the groundwater equipotential surface, hydraulic head gradient, and estimation of the groundwater budget of the aquifer. GIS is used for spatial database development, integration with a remote sensing, and numerical groundwater flow modeling capabilities. The thematic layers of soils, land use, hydrology, infrastructure, and climate were developed using GIS. The Arcview GIS software is used as additive tool to develop supportive data for numerical groundwater flow modeling and integration and presentation of image processing and modeling results. The groundwater flow model was calibrated to simulate future changes in piezometric heads from the period 2006 to 2020. Different scenarios were developed to study the impact of extreme climatic conditions (drought/flood) and variable groundwater abstraction on the regional groundwater system. The model results indicated a significant response in watertable due to external influential factors. The developed model provides an effective tool for evaluating better management options for monitoring future groundwater development in the study area.
International Nuclear Information System (INIS)
Altman, S.J.; Ho, C.K.; Arnold, B.W.; McKenna, S.A.
1995-01-01
Unsaturated flow has been modeled through four cross-sections at Yucca Mountain, Nevada, for the purpose of determining groundwater particle travel times from the potential repository to the water table. This work will be combined with the results of flow modeling in the saturated zone for the purpose of evaluating the suitability of the potential repository under the criteria of 10CFR960. One criterion states, in part, that the groundwater travel time (GWTT) from the repository to the accessible environment must exceed 1,000 years along the fastest path of likely and significant radionuclide travel. Sensitivity analyses have been conducted for one geostatistical realization of one cross-section for the purpose of (1) evaluating the importance of hydrological parameters having some uncertainty and (2) examining conceptual models of flow by altering the numerical implementation of the conceptual model (dual permeability (DK) and the equivalent continuum model (ECM). Results of comparisons of the ECM and DK model are also presented in Ho et al
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
Ground-water flow in low permeability environments
Neuzil, Christopher E.
1986-01-01
Certain geologic media are known to have small permeability; subsurface environments composed of these media and lacking well developed secondary permeability have groundwater flow sytems with many distinctive characteristics. Moreover, groundwater flow in these environments appears to influence the evolution of certain hydrologic, geologic, and geochemical systems, may affect the accumulation of pertroleum and ores, and probably has a role in the structural evolution of parts of the crust. Such environments are also important in the context of waste disposal. This review attempts to synthesize the diverse contributions of various disciplines to the problem of flow in low-permeability environments. Problems hindering analysis are enumerated together with suggested approaches to overcoming them. A common thread running through the discussion is the significance of size- and time-scale limitations of the ability to directly observe flow behavior and make measurements of parameters. These limitations have resulted in rather distinct small- and large-scale approaches to the problem. The first part of the review considers experimental investigations of low-permeability flow, including in situ testing; these are generally conducted on temporal and spatial scales which are relatively small compared with those of interest. Results from this work have provided increasingly detailed information about many aspects of the flow but leave certain questions unanswered. Recent advances in laboratory and in situ testing techniques have permitted measurements of permeability and storage properties in progressively “tighter” media and investigation of transient flow under these conditions. However, very large hydraulic gradients are still required for the tests; an observational gap exists for typical in situ gradients. The applicability of Darcy's law in this range is therefore untested, although claims of observed non-Darcian behavior appear flawed. Two important nonhydraulic
Poiseuille equation for steady flow of fractal fluid
Tarasov, Vasily E.
2016-07-01
Fractal fluid is considered in the framework of continuous models with noninteger dimensional spaces (NIDS). A recently proposed vector calculus in NIDS is used to get a description of fractal fluid flow in pipes with circular cross-sections. The Navier-Stokes equations of fractal incompressible viscous fluids are used to derive a generalization of the Poiseuille equation of steady flow of fractal media in pipe.
Statistically derived conservation equations for fluid particle flows
International Nuclear Information System (INIS)
Reyes, J.N. Jr.
1989-01-01
The behavior of water droplets in a heated nuclear fuel channel is of significant interest to nuclear reactor safety studies pertaining to loss-of-coolant accidents. This paper presents the derivation of the mass, momentum, and energy conservation equations for a distribution of fluid particles (bubbles or droplets) transported by a continuous fluid medium. When coupled with the appropriate closure equations, the conservation equations can be used to model nonequilibrium, two-phase, dispersed, fluid flow behavior
Navier-Stokes-like equations for traffic flow.
Velasco, R M; Marques, W
2005-10-01
The macroscopic traffic flow equations derived from the reduced Paveri-Fontana equation are closed starting with the maximization of the informational entropy. The homogeneous steady state taken as a reference is obtained for a specific model of the desired velocity and a kind of Chapman-Enskog method is developed to calculate the traffic pressure at the Navier-Stokes level. Numerical solution of the macroscopic traffic equations is obtained and its characteristics are analyzed.
Regional-to-site scale groundwater flow in Kivetty
Energy Technology Data Exchange (ETDEWEB)
Kattilakoski, E. [VTT Energy, Espoo (Finland); Meszaros, F. [The Relief Laboratory, Harskut (Hungary)
1999-04-01
The work describing numerical groundwater flow modelling at the Kivetty site serves as a background report for the safety assessment TILA-99. The site scale can roughly be taken as the scale of detailed borehole investigations, which have probed the bedrock of Kivetty over about 3 km{sup 2} large and 1 km deep volume. The site model in this work covers an area of about 16 km{sup 2}. The depth of the model is 2000 m. The site scale flow modelling produced characteristics of the deep groundwater flow both under the natural conditions and in the case of a spent fuel repository. The hydraulic gradient in the intact rock between the repository and the fracture zone nearest to it (about 50 m off) was assessed for the block scale model. The result quantities were the hydraulic head h (as the base quantity) and its gradient in selected cross sections and fracture zones, the flow rates around the repository, flow paths and discharge areas of the water from the repository. Two repository layouts were discussed. The numerical simulations were performed with the FEFTRA code based on the porous medium concept and the finite element method. The regional model with a no-flow boundary condition at the bottom and on the lateral edges was firstly used to confirm the hydraulic head boundary condition on the lateral edges of an interior site model (having a no-flow boundary condition at the bottom). The groundwater table was used as the hydraulic head boundary condition at the surface of each model. Both the conductivity of the bedrock (modeled with three-dimensional elements) and the transmissivities of the fracture zones (described with two-dimensional elements in the three-dimensional mesh) decreased as a function of the depth. All the results were derived from the site model. With the exception of the western part of Repository A the outlined repositories are located underneath Kumpuvuori, where the flow has a significant subvertical component. The horizontal component of the deep
Regional-to-site scale groundwater flow in Kivetty
International Nuclear Information System (INIS)
Kattilakoski, E.; Meszaros, F.
1999-04-01
The work describing numerical groundwater flow modelling at the Kivetty site serves as a background report for the safety assessment TILA-99. The site scale can roughly be taken as the scale of detailed borehole investigations, which have probed the bedrock of Kivetty over about 3 km 2 large and 1 km deep volume. The site model in this work covers an area of about 16 km 2 . The depth of the model is 2000 m. The site scale flow modelling produced characteristics of the deep groundwater flow both under the natural conditions and in the case of a spent fuel repository. The hydraulic gradient in the intact rock between the repository and the fracture zone nearest to it (about 50 m off) was assessed for the block scale model. The result quantities were the hydraulic head h (as the base quantity) and its gradient in selected cross sections and fracture zones, the flow rates around the repository, flow paths and discharge areas of the water from the repository. Two repository layouts were discussed. The numerical simulations were performed with the FEFTRA code based on the porous medium concept and the finite element method. The regional model with a no-flow boundary condition at the bottom and on the lateral edges was firstly used to confirm the hydraulic head boundary condition on the lateral edges of an interior site model (having a no-flow boundary condition at the bottom). The groundwater table was used as the hydraulic head boundary condition at the surface of each model. Both the conductivity of the bedrock (modeled with three-dimensional elements) and the transmissivities of the fracture zones (described with two-dimensional elements in the three-dimensional mesh) decreased as a function of the depth. All the results were derived from the site model. With the exception of the western part of Repository A the outlined repositories are located underneath Kumpuvuori, where the flow has a significant subvertical component. The horizontal component of the deep
Influence of irrigation on the level, salinity and flow of groundwater at ...
African Journals Online (AJOL)
2010-03-31
Mar 31, 2010 ... piezometers had to be measured, all readings were taken within 3 days. Water levels were measured to estab- lish the effect of rainfall, drainage and irrigation on the groundwater level. These levels were also used to gener- ate groundwater contour maps and to determine the groundwater flow directions.
Flow visualization via partial differential equations
Preusser, T.; Rumpf, M.; Telea, A.C.; Möller, T.; Hamann, B.; Russell, R.D.
2009-01-01
The visualization of stationary and time-dependent flow is an important and chaltenging topic in scientific visualization. lts aim is 10 represent transport phenomena govemed by vector fjelds in an intuitively understandable way. In this paper. we review the use of methods based on partial
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
Groundwater flow modelling of periods with temperate climate conditions - Laxemar
International Nuclear Information System (INIS)
Joyce, Steven; Simpson, Trevor; Hartley, Lee; Applegate, David; Hoek, Jaap; Jackson, Peter; Roberts, David; Swan, David; Gylling, Bjoern; Marsic, Niko; Rhen, Ingvar
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. This report concerns the modelling of a repository at the Laxemar-Simpevarp site during temperate climate conditions as a comparison to corresponding modelling carried out for Forsmark /Joyce et al. 2010/. The collation and implementation of onsite hydrogeological and hydrogeochemical data from previous reports are used in the construction of a Hydrogeological base case (reference case conceptualisation) and then an examination of various areas of uncertainty within the current understanding by a series of model variants. The Hydrogeological base case models at three different scales, 'repository', 'site' and 'regional' make use of a discrete fracture network (DFN) and equivalent continuous porous medium (ECPM) models. The use of hydrogeological models allow for the investigation of the groundwater flow from a deep disposal facility to the biosphere and for the calculation of performance measures that will provide an input to the site performance assessment. The focus of the study described in this report has been to perform numerical simulations of the hydrogeological system from post-closure and throughout the temperate period up until the receding shoreline leaves the modelling domain at around 15,000 AD. Besides providing quantitative results for the immediate temperate period following post-closure, these results are also intended to give a qualitative indication of the evolution of the groundwater system during future temperate periods within an ongoing cycle of glacial/inter-glacial events
Groundwater flow modelling of periods with temperate climate conditions - Forsmark
Energy Technology Data Exchange (ETDEWEB)
Joyce, Steven; Simpson, Trevor; Hartley, Lee; Applegate, David; Hoek, Jaap; Jackson, Peter; Swan, David (Serco Technical Consulting Services (United Kingdom)); Marsic, Niko (Kemakta Konsult AB (Sweden)); Follin, Sven (SF GeoLogic AB (Sweden))
2010-11-15
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 climate conditions and the simulations carried out contribute to the overall evaluation of the repository design and long-term radiological safety. This report concerns the modelling of a repository at the Forsmark site during temperate conditions; i.e. from post-closure and throughout the temperate period up until the receding shoreline leaves the modelling domain at around 12,000 AD. The collation and implementation of onsite hydrogeological and hydrogeochemical data from previous reports are used in the construction of a hydrogeological base case (reference case conceptualisation) and then in an examination of various areas of uncertainty within the current understanding by a series of model variants. The hydrogeological base case models at three different scales, 'repository', 'site' and 'regional', make use of continuous porous medium (CPM), equivalent continuous porous medium (ECPM) and discrete fracture network (DFN) models. The use of hydrogeological models allow for the investigation of the groundwater flow from a deep disposal facility to the biosphere and for the calculation of performance measures that will provide an input to the site performance assessment. The focus of the study described in this report has been to perform numerical simulations of the hydrogeological system from post-closure and throughout the temperate period. Besides providing quantitative results for the immediate temperate period following post-closure, these results are also intended to give a qualitative indication of the evolution of the groundwater system during future temperate periods within an ongoing cycle of glacial/inter-glacial events
Groundwater flow modelling of periods with temperate climate conditions - Laxemar
Energy Technology Data Exchange (ETDEWEB)
Joyce, Steven; Simpson, Trevor; Hartley, Lee; Applegate, David; Hoek, Jaap; Jackson, Peter; Roberts, David; Swan, David (Serco Technical Consulting Services (United Kingdom)); Gylling, Bjoern; Marsic, Niko (Kemakta Konsult AB, Stockholm (Sweden)); Rhen, Ingvar (SWECO Environment AB, Falun (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 concerns the modelling of a repository at the Laxemar-Simpevarp site during temperate climate conditions as a comparison to corresponding modelling carried out for Forsmark /Joyce et al. 2010/. The collation and implementation of onsite hydrogeological and hydrogeochemical data from previous reports are used in the construction of a Hydrogeological base case (reference case conceptualisation) and then an examination of various areas of uncertainty within the current understanding by a series of model variants. The Hydrogeological base case models at three different scales, 'repository', 'site' and 'regional' make use of a discrete fracture network (DFN) and equivalent continuous porous medium (ECPM) models. The use of hydrogeological models allow for the investigation of the groundwater flow from a deep disposal facility to the biosphere and for the calculation of performance measures that will provide an input to the site performance assessment. The focus of the study described in this report has been to perform numerical simulations of the hydrogeological system from post-closure and throughout the temperate period up until the receding shoreline leaves the modelling domain at around 15,000 AD. Besides providing quantitative results for the immediate temperate period following post-closure, these results are also intended to give a qualitative indication of the evolution of the groundwater system during future temperate periods within an ongoing cycle of glacial/inter-glacial events
Groundwater recharge and flow on Montserrat, West Indies: Insights from groundwater dating
Directory of Open Access Journals (Sweden)
Brioch Hemmings
2015-09-01
New hydrological insights: δ2H and δ18O analysis indicates uniform recharge elevations for groundwaters on Montserrat. CFC-11 and CFC-12 analysis reveals age differences between isotopically similar, high elevation springs and low elevation aquifer waters. Low CFC concentrations within a confined low elevation aquifer suggest water ages of ∼45 years. High CFC concentrations in the northern and western springs are explained by rapid infiltration of cool (high CFC concentration rainfall into saturated compartments, with flow through the vadose zone to the phreatic zone dominated by compartment flow. Lower CFC concentrations in a number of aligned warmer springs suggest a contribution from older, warmer waters from depth. Temperatures and CFC concentrations indicate older component supply rates of up to 8 L/s to the highest yielding spring on Centre Hills, with contributions of up to 75% in the warmest spring waters.
SR-Site groundwater flow modelling methodology, setup and results
International Nuclear Information System (INIS)
Selroos, Jan-Olof; Follin, Sven
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 three groundwater flow modelling studies. These are performed within the SR-Site project and represent time periods with different climate conditions. The simulations carried out contribute to the overall evaluation of the repository design and long-term radiological safety. Three time periods are addressed; the Excavation and operational phases, the Initial period of temperate climate after closure, and the Remaining part of the reference glacial cycle. The present report is a synthesis of the background reports describing the modelling methodology, setup, and results. It is the primary reference for the conclusions drawn in a SR-Site specific context concerning groundwater flow during the three climate periods. These conclusions are not necessarily provided explicitly in the background reports, but are based on the results provided in these reports. The main results and comparisons presented in the present report are summarised in the SR-Site Main report
SR-Site groundwater flow modelling methodology, setup and results
Energy Technology Data Exchange (ETDEWEB)
Selroos, Jan-Olof (Swedish Nuclear Fuel and Waste Management Co., Stockholm (Sweden)); Follin, Sven (SF GeoLogic AB, Taeby (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 three groundwater flow modelling studies. These are performed within the SR-Site project and represent time periods with different climate conditions. The simulations carried out contribute to the overall evaluation of the repository design and long-term radiological safety. Three time periods are addressed; the Excavation and operational phases, the Initial period of temperate climate after closure, and the Remaining part of the reference glacial cycle. The present report is a synthesis of the background reports describing the modelling methodology, setup, and results. It is the primary reference for the conclusions drawn in a SR-Site specific context concerning groundwater flow during the three climate periods. These conclusions are not necessarily provided explicitly in the background reports, but are based on the results provided in these reports. The main results and comparisons presented in the present report are summarised in the SR-Site Main report.
Determination of multiple solutions of load flow equations
Indian Academy of Sciences (India)
This paper is concerned with the problem of finding all the real solutions (all components of the solution vector must be real values) of load flow equations. Solutions in which some of the components are complex values are of no interest as they have no physical significance as a load flow solution. This problem issignificant ...
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
Groundwater Recharge and Flow Processes in Taihang Mountains, a Semi-humid Region, North China
Sakakibara, Koichi; Tsujimura, Maki; Song, Xianfang; Zhang, Jie
2015-04-01
Groundwater flow/recharge variations in time and space are crucial for effective water management especially in semi-arid and semi-humid regions. In order to reveal comprehensive groundwater flow/recharge processes in a catchment with a large topographical relief and seasonal hydrological variations, intensive field surveys were undertaken at 4 times in different seasons (June 2011, August 2012, November 2012, February 2014) in the Wangkuai watershed, Taihang mountains, which is a main groundwater recharge area of the North China Plain. The groundwater, spring, stream water and reservoir water were taken, and inorganic solute constituents and stable isotopes of oxygen-18 and deuterium were determined on all water samples. Also, the stream flow rate and the depth of groundwater table were observed. The stable isotopic compositions and inorganic solute constituents in the groundwater are depleted and shown similar values as those of the surface water at the mountain-plain transitional area. Additionally, the groundwater in the vicinity of the Wangkuai Reservoir presents clearly higher stable isotopic compositions and lower d-excess than those of the stream water, indicating the groundwater around the reservoir is affected by evaporation same as the Wangkuai Reservoir itself. Hence, the surface water in the mountain-plain transitional area and Wangkuai Reservoir are principal groundwater recharge sources. An inversion analysis and simple mixing model were applied in the Wangkuai watershed using stable isotopes of oxygen-18 and deuterium to construct a groundwater flow model. The model shows that multi-originated groundwater flows from upstream to downstream along topography with certain mixing. In addition, the groundwater recharge occurs dominantly at the altitude from 421 m to 953 m, and the groundwater recharge rate by the Wangkuai Reservoir is estimated to be 2.4 % of the total groundwater recharge in the Wangkuai watershed. Therefore, the stream water and
Ideal, steady-state, axisymmetric magnetohydrodynamic equations with flow
International Nuclear Information System (INIS)
Baransky, Y.A.
1987-01-01
The motivation of this study is to gain additional understanding of the effect of rotation on the equilibrium of a plasma. The axisymmetric equilibria of ideal magnetohydrodynamics (MHD) with flow have been studied numerically and analytically. A general discussion is provided of previous work on plasmas with flow and comparisons are made to the static model. A variational principle has been derived for the two dimensional problem with comments as to appropriate boundary conditions. An inverse aspect ratio expansion has been used for a study of the toroidal flow equation for both low- and high-β. The inverse aspect ratio expansion has also been used for a study of equations with both poloidal and toroidal flow. An overview is provided of the adaptive finite-difference code which was developed to solve the full equations. (FI)
THE STATEMENT OF CASH FLOWS USING FINANCIAL STATEMENT EQUATIONS
Harold Fletcher; Thomas Ulrich
2010-01-01
This paper addresses one of the more difficult topics in teaching MBA level financial management, the statement of cash flows. By employing financial statement equations in preparing the statement of cash flows, students: (1) are employing tools that they are more familiar and comfortable with which mitigates their anxiety and enhances their understanding, (2) are better able to understand the logic of the statement of cash flows and the relationships that exist between it and the income stat...
Coupled equations for transient water flow, heat flow, and ...
Indian Academy of Sciences (India)
interacting processes, including flow of fluids, deformation of porous materials, chemical reactions, and transport of ... systems involving the flow of water, heat, and deformation. Such systems are ..... Defined thus, αI is independent of boundary con- ditions in an ... perature change with free deformation at constant total stress ...
International Nuclear Information System (INIS)
Davison, C.; Brown, A.; Gascoyne, M.; Stevenson, D.; Ophori, D.
2000-01-01
Atomic Energy of Canada Limited (AECL) conducted a ten-year long groundwater flow study of a 1050 km 2 region of fractured crystalline rock in southeastern Manitoba to illustrate how an understanding of large scale groundwater flow can be used to assist in selecting a hydraulically favourable location for the deep geological disposal of nuclear fuel waste. The study involved extensive field investigations that included the drilling testing, sampling and monitoring of twenty deep boreholes distributed at detailed study areas across the region. The surface and borehole geotechnical investigations were used to construct a conceptual model of the main litho-structural features that controlled groundwater flow through the crystalline rocks of the region. Eighty-three large fracture zones and other spatial domains of moderately fractured and sparsely fractured rocks were represented in a finite element model of the area to simulate regional groundwater flow. The groundwater flow model was calibrated to match the observed groundwater recharge rate and the hydraulic heads measured in the network of deep boreholes. Particle tracking was used to determine the pathways and travel times from different depths in the velocity field of the calibrated groundwater flow model. The results were used to identify locations in the regional flow field that maximize the time it takes for groundwater to travel to surface discharge areas through long, slow groundwater pathways. One of these locations was chosen as a good hypothetical location for situating a nuclear fuel waste disposal vault at 750 m depth. (authors)
Estimation of groundwater flow rate using the decay of 222Rn in a well
International Nuclear Information System (INIS)
Hamada, Hiromasa
1999-01-01
A method of estimating groundwater flow rate using the decay of 222 Rn in a well was investigated. Field application revealed that infiltrated water (i.e., precipitation, pond water and irrigation water) accelerated groundwater flow. In addition, the depth at which groundwater was influenced by surface water was determined. The velocity of groundwater in a test well was estimated to be of the order of 10 -6 cm s -1 , based on the ratio of 222 Rn concentration in groundwater before and after it flowed into the well. This method is applicable for monitoring of groundwater flow rate where the velocity in a well is from 10 -5 to 10 -6 cm s -1
Representation of an open repository in groundwater flow models
International Nuclear Information System (INIS)
Painter, Scott; Sun, Alexander
2005-08-01
The effect of repository tunnels on groundwater flow has been identified as a potential issue for the nuclear waste repository being considered by SKB for a fractured granite formation in Sweden. In particular, the following pre-closure and post-closure processes have been identified as being important: inflows into open tunnels as functions of estimated grouting efficiencies, drawdown of the water table in the vicinity of the repository, upcoming of saline water, 'turnover' of surface water in the upper bedrock, and resaturation of backfilled tunnels following repository closure. The representation of repository tunnels within groundwater models is addressed in this report. The primary focus is on far-field flow that is modeled with a continuum porous medium approximation. Of particular interest are the consequences of the tunnel representation on the transient response of the groundwater system to repository operations and repository closure, as well as modeling issues such as how the water-table free surface and the coupling to near-surface hydrogeology should be handled. The overall objectives are to understand the consequences of current representations and to identify appropriate approximations for representing open tunnels in future groundwater modeling studies. The following conclusions can be drawn from the results of the simulations: 1. Two-phase flow may be induced in the vicinity of repository tunnels during repository pre-closure operations, but the formation of a two-phase flow region will not significantly affect far-field flow or inflows into tunnels. 2. The water table will be drawn down to the repository horizon and tunnel inflows will reach a steady-state value within about 5 years. 3. Steady-state inflows at the repository edge are estimated to be about 250 m 3 /year per meter of tunnel. Inflows will be greater during the transient de-watering period and less for tunnel locations closer to the repository center. 4. Significant amounts of water
Representation of an open repository in groundwater flow models
Energy Technology Data Exchange (ETDEWEB)
Painter, Scott; Sun, Alexander [Southwest Research Inst., San Antonio, TX (United States). Center for Nuclear Waste Regulatory Analyses
2005-08-01
The effect of repository tunnels on groundwater flow has been identified as a potential issue for the nuclear waste repository being considered by SKB for a fractured granite formation in Sweden. In particular, the following pre-closure and post-closure processes have been identified as being important: inflows into open tunnels as functions of estimated grouting efficiencies, drawdown of the water table in the vicinity of the repository, upcoming of saline water, 'turnover' of surface water in the upper bedrock, and resaturation of backfilled tunnels following repository closure. The representation of repository tunnels within groundwater models is addressed in this report. The primary focus is on far-field flow that is modeled with a continuum porous medium approximation. Of particular interest are the consequences of the tunnel representation on the transient response of the groundwater system to repository operations and repository closure, as well as modeling issues such as how the water-table free surface and the coupling to near-surface hydrogeology should be handled. The overall objectives are to understand the consequences of current representations and to identify appropriate approximations for representing open tunnels in future groundwater modeling studies. The following conclusions can be drawn from the results of the simulations: 1. Two-phase flow may be induced in the vicinity of repository tunnels during repository pre-closure operations, but the formation of a two-phase flow region will not significantly affect far-field flow or inflows into tunnels. 2. The water table will be drawn down to the repository horizon and tunnel inflows will reach a steady-state value within about 5 years. 3. Steady-state inflows at the repository edge are estimated to be about 250 m{sup 3}/year per meter of tunnel. Inflows will be greater during the transient de-watering period and less for tunnel locations closer to the repository center. 4. Significant
STRING 3: An Advanced Groundwater Flow Visualization Tool
Schröder, Simon; Michel, Isabel; Biedert, Tim; Gräfe, Marius; Seidel, Torsten; König, Christoph
2016-04-01
The visualization of 3D groundwater flow is a challenging task. Previous versions of our software STRING [1] solely focused on intuitive visualization of complex flow scenarios for non-professional audiences. STRING, developed by Fraunhofer ITWM (Kaiserslautern, Germany) and delta h Ingenieurgesellschaft mbH (Witten, Germany), provides the necessary means for visualization of both 2D and 3D data on planar and curved surfaces. In this contribution we discuss how to extend this approach to a full 3D tool and its challenges in continuation of Michel et al. [2]. This elevates STRING from a post-production to an exploration tool for experts. In STRING moving pathlets provide an intuition of velocity and direction of both steady-state and transient flows. The visualization concept is based on the Lagrangian view of the flow. To capture every detail of the flow an advanced method for intelligent, time-dependent seeding is used building on the Finite Pointset Method (FPM) developed by Fraunhofer ITWM. Lifting our visualization approach from 2D into 3D provides many new challenges. With the implementation of a seeding strategy for 3D one of the major problems has already been solved (see Schröder et al. [3]). As pathlets only provide an overview of the velocity field other means are required for the visualization of additional flow properties. We suggest the use of Direct Volume Rendering and isosurfaces for scalar features. In this regard we were able to develop an efficient approach for combining the rendering through raytracing of the volume and regular OpenGL geometries. This is achieved through the use of Depth Peeling or A-Buffers for the rendering of transparent geometries. Animation of pathlets requires a strict boundary of the simulation domain. Hence, STRING needs to extract the boundary, even from unstructured data, if it is not provided. In 3D we additionally need a good visualization of the boundary itself. For this the silhouette based on the angle of
Groundwater flow modelling of an abandoned partially open repository
Energy Technology Data Exchange (ETDEWEB)
Bockgaard, Niclas (Golder Associates AB (Sweden))
2010-12-15
As a part of the license application, according to the nuclear activities act, 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 modelling study presented here serves as an input for analyses of so-called future human actions that may affect the repository. The objective of the work was to investigate the hydraulic influence of an abandoned partially open repository. The intention was to illustrate a pessimistic scenario of the effect of open tunnels in comparison to the reference closure of the repository. The effects of open tunnels were studied for two situations with different boundary conditions: A 'temperate' case with present-day boundary conditions and a generic future 'glacial' case with an ice sheet covering the repository. The results were summarized in the form of analyses of flow in and out from open tunnels, the effect on hydraulic head and flow in the surrounding rock volume, and transport performance measures of flow paths from the repository to surface
Groundwater flow modelling of an abandoned partially open repository
International Nuclear Information System (INIS)
Bockgaard, Niclas
2010-12-01
As a part of the license application, according to the nuclear activities act, 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 modelling study presented here serves as an input for analyses of so-called future human actions that may affect the repository. The objective of the work was to investigate the hydraulic influence of an abandoned partially open repository. The intention was to illustrate a pessimistic scenario of the effect of open tunnels in comparison to the reference closure of the repository. The effects of open tunnels were studied for two situations with different boundary conditions: A 'temperate' case with present-day boundary conditions and a generic future 'glacial' case with an ice sheet covering the repository. The results were summarized in the form of analyses of flow in and out from open tunnels, the effect on hydraulic head and flow in the surrounding rock volume, and transport performance measures of flow paths from the repository to surface
Exactly averaged equations for flow and transport in random media
International Nuclear Information System (INIS)
Shvidler, Mark; Karasaki, Kenzi
2001-01-01
It is well known that exact averaging of the equations of flow and transport in random porous media can be realized only for a small number of special, occasionally exotic, fields. On the other hand, the properties of approximate averaging methods are not yet fully understood. For example, the convergence behavior and the accuracy of truncated perturbation series. Furthermore, the calculation of the high-order perturbations is very complicated. These problems for a long time have stimulated attempts to find the answer for the question: Are there in existence some exact general and sufficiently universal forms of averaged equations? If the answer is positive, there arises the problem of the construction of these equations and analyzing them. There exist many publications related to these problems and oriented on different applications: hydrodynamics, flow and transport in porous media, theory of elasticity, acoustic and electromagnetic waves in random fields, etc. We present a method of finding the general form of exactly averaged equations for flow and transport in random fields by using (1) an assumption of the existence of Green's functions for appropriate stochastic problems, (2) some general properties of the Green's functions, and (3) the some basic information about the random fields of the conductivity, porosity and flow velocity. We present a general form of the exactly averaged non-local equations for the following cases. 1. Steady-state flow with sources in porous media with random conductivity. 2. Transient flow with sources in compressible media with random conductivity and porosity. 3. Non-reactive solute transport in random porous media. We discuss the problem of uniqueness and the properties of the non-local averaged equations, for the cases with some types of symmetry (isotropic, transversal isotropic, orthotropic) and we analyze the hypothesis of the structure non-local equations in general case of stochastically homogeneous fields. (author)
Numerical simulation of groundwater flow for the Yakima River basin aquifer system, Washington
Ely, D.M.; Bachmann, M.P.; Vaccaro, J.J.
2011-01-01
A regional, three-dimensional, transient numerical model of groundwater flow was constructed for the Yakima River basin aquifer system to better understand the groundwater-flow system and its relation to surface-water resources. The model described in this report can be used as a tool by water-management agencies and other stakeholders to quantitatively evaluate proposed alternative management strategies that consider the interrelation between groundwater availability and surface-water resources.
Chen, Ching-Fang; Chen, Jui-Sheng; Jang, Cheng-Shin
2014-05-01
As a result of rapid economic growth in the Pingtung Plain, the use of groundwater resources has changed dramatically. The groundwater is quite rich in the Pingtung plain and the most important water sources. During the several decades, a substantial amount of groundwater has been pumped for the drinking, irrigation and aquaculture water supplies. However, because the sustainable use concept of groundwater resources is lack, excessive pumping of groundwater causes the occurrence of serious land subsidence and sea water intrusion. Thus, the management and conservation of groundwater resources in the Pingtung plain are considerably critical. This study aims to assess the conjunct use effect of groundwater and surface water in the Pingtung plain on recharge by reducing the amount of groundwater extraction. The groundwater quality variability and groundwater flow models are combined to spatially analyze potential zones of groundwater used for multi-purpose in the Pingtung Plain. First, multivariate indicator kriging (MVIK) is used to analyze spatial variability of groundwater quality based on drinking, aquaculture and irrigation water quality standards, and probabilistically delineate suitable zones in the study area. Then, the groundwater flow model, Processing MODFLOW (PMWIN), is adopted to simulate groundwater flow. The groundwater flow model must be conducted by the calibration and verification processes, and the regional groundwater recovery is discussed when specified water rights are replaced by surface water in the Pingtung plain. Finally, the most suitable zones of reducing groundwater use are determined for multi-purpose according to combining groundwater quality and quantity. The study results can establish a sound and low-impact management plan of groundwater resources utilization for the multi-purpose groundwater use, and prevent decreasing ground water tables, and the occurrence of land subsidence and sea water intrusion in the Pingtung plain.
Directory of Open Access Journals (Sweden)
Xiaoyuan Cao
2017-07-01
Full Text Available The production of nuclear energy will result in high-level radioactive waste (HLRW, which brings potential environmental dangers. Selecting a proper disposal repository is a crucial step in the development of nuclear energy. This paper introduces firstly the hydrogeological conditions of the Beishan area in China. Next, a regional groundwater model is constructed using a multiphase flow simulator to analyze the groundwater flow pattern in the Beishan area. Model calibration shows that the simulated and observed hydraulic heads match well, and the simulated regional groundwater flow pattern is similar to the surface flow pattern from the channel network, indicating that the groundwater flow is mainly dependent on the topography. In addition, the simulated groundwater storage over the period from 2003 to 2014 is similar to the trend derived from the Gravity Recovery and Climate Experiment satellite-derived results. Last, the established model is used to evaluate the influences of the extreme climate and regional faults on the groundwater flow pattern. It shows that they do not have a significant influence on the regional groundwater flow patterns. This study will provide a preliminary reference for the regional groundwater flow assessment in the site of the HLRW in China.
Several advances in the analytic element method have been made to enhance its performance and facilitate three-dimensional ground-water flow modeling in a regional aquifer setting. First, a new public domain modular code (ModAEM) has been developed for modeling ground-water flow ...
International Nuclear Information System (INIS)
Kawanishi, M.; Miyakawa, K.; Hirata, Y.
2001-01-01
For the confirmation of safety for the geological disposal of radioactive wastes, it is very important to demonstrate the groundwater flow by in-situ investigation in the deep underground. We have developed a groundwater flow meter to measure simultaneously the velocity and direction of groundwater flow by means of detecting the electric potential difference between the groundwater to evaluate and the distilled water as a tracer in a single well. In this paper, we describe the outline of the groundwater flow meter system developed by CRIEPI and Taisei-Kiso-Sekkei Co. Ltd. and the evaluation methodology for observed data by using it in fractured rocks. Furthermore, applied results to in-situ tests at the Tounou mine of Japan Nuclear Fuel Cycle Development Institute (JNC) and the Aespoe Hard Rock Laboratory (HRL) of Swedish Nuclear Fuel and Waste Management Co. (SK) are described. Both sites are different type of fractured rock formations of granite. From these results, it was made clear that this flow meter system can be practically used to measure the groundwater flow direction and velocity as low as order of 1x10 -3 ∼10 -7 cm/sec. (author)
Groundwater flow modelling of the excavation and operational phases - Forsmark
International Nuclear Information System (INIS)
Svensson, Urban; Follin, Sven
2010-07-01
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 climate conditions and the simulations carried out contribute to the overall evaluation of the repository design and long-term radiological safety. The modelling study reported here presents calculated inflow rates, drawdown of the groundwater table and upconing of deep saline water for different levels of grouting efficiency during the excavation and operational phases of a final repository at Forsmark. The inflow calculations are accompanied by a sensitivity study, which among other matters handles the impact of parameter heterogeneity, different deposition hole rejection criteria, and the SFR facility (the repository for short-lived radioactive waste located approximately 1 km to the north of the investigated candidate area for a final repository at Forsmark). The report also presents tentative modelling results for the duration of the saturation phase, which starts once the used parts of the repository are being backfilled
Groundwater flow modelling of the excavation and operational phases - Forsmark
Energy Technology Data Exchange (ETDEWEB)
Svensson, Urban (Computer-aided Fluid Engineering AB, Lyckeby (Sweden)); Follin, Sven (SF GeoLogic AB, Taeby (Sweden))
2010-07-15
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 climate conditions and the simulations carried out contribute to the overall evaluation of the repository design and long-term radiological safety. The modelling study reported here presents calculated inflow rates, drawdown of the groundwater table and upconing of deep saline water for different levels of grouting efficiency during the excavation and operational phases of a final repository at Forsmark. The inflow calculations are accompanied by a sensitivity study, which among other matters handles the impact of parameter heterogeneity, different deposition hole rejection criteria, and the SFR facility (the repository for short-lived radioactive waste located approximately 1 km to the north of the investigated candidate area for a final repository at Forsmark). The report also presents tentative modelling results for the duration of the saturation phase, which starts once the used parts of the repository are being backfilled.
Diagonalizing quadratic bosonic operators by non-autonomous flow equations
Bach, Volker
2016-01-01
The authors study a non-autonomous, non-linear evolution equation on the space of operators on a complex Hilbert space. They specify assumptions that ensure the global existence of its solutions and allow them to derive its asymptotics at temporal infinity. They demonstrate that these assumptions are optimal in a suitable sense and more general than those used before. The evolution equation derives from the Brocketâe"Wegner flow that was proposed to diagonalize matrices and operators by a strongly continuous unitary flow. In fact, the solution of the non-linear flow equation leads to a diagonalization of Hamiltonian operators in boson quantum field theory which are quadratic in the field.
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
D is a two-dimensional finite element numerical model for transient or steady state analysis of coupled processes of advective and conductive heat transfers in a porous continuum and buoyancy driven groundwater flow in a saturated, fractured, porous medium. The governing equations consist of a set of coupled, quasilinear partial differential equations that are based on the physical laws of fluid continuity and conservation of momentum and energy. The solutions are based on a Galerkin finite element scheme, using a block diagonal frontal solution technique. The computational network consists of both quadrilateral and triangular elements to model the continuum regions of the spatial domain, and line elements to represent the discrete fractures within the domain. A Newton-Raphson algorithm is embedded in the Galerkin functional to formulate the problems in terms of the incremental changes in the dependent variables. This method allows substantial flexibility in discretization of the spatial domain. The flow equations are solved simultaneously, and the flow and heat transfer equations are solved in alternating sequence. The simulation domain may be modeled in two Cartesian dimensions or in a radial coordinate system that is symmetric around the vertical axis. 3 - Restrictions on the complexity of the problem: Maxima of 3000 nodes, 960 elements, 225 heat source elements, 50 thermal load points, 25 material types, 25 time intervals, 5 binary input files. The number of nodes define the element: 8 nodes specify a quadrilateral, 6 nodes specify a triangular shape and 3 nodes specify a linear element. The element aspect ratio affects the accuracy of the results and should be kept at a value below 100. The reference temperature must be between 0.0 and 300.0 degrees C. MAGNUM2D requires the proprietary CA-DISSPLA graphics library to utilize the graphics post processor; this program is not included
Groundwater flow processes and mixing in active volcanic systems: the case of Guadalajara (Mexico)
Hernández-Antonio, A.; Mahlknecht, J.; Tamez-Meléndez, C.; Ramos-Leal, J.; Ramírez-Orozco, A.; Parra, R.; Ornelas-Soto, N.; Eastoe, C. J.
2015-09-01
Groundwater chemistry and isotopic data from 40 production wells in the Atemajac and Toluquilla valleys, located in and around the Guadalajara metropolitan area, were determined to develop a conceptual model of groundwater flow processes and mixing. Stable water isotopes (δ2H, δ18O) were used to trace hydrological processes and tritium (3H) to evaluate the relative contribution of modern water in samples. Multivariate analysis including cluster analysis and principal component analysis were used to elucidate distribution patterns of constituents and factors controlling groundwater chemistry. Based on this analysis, groundwater was classified into four groups: cold groundwater, hydrothermal groundwater, polluted groundwater and mixed groundwater. Cold groundwater is characterized by low temperature, salinity, and Cl and Na concentrations and is predominantly of Na-HCO3-type. It originates as recharge at "La Primavera" caldera and is found predominantly in wells in the upper Atemajac Valley. Hydrothermal groundwater is characterized by high salinity, temperature, Cl, Na and HCO3, and the presence of minor elements such as Li, Mn and F. It is a mixed-HCO3 type found in wells from Toluquilla Valley and represents regional flow circulation through basaltic and andesitic rocks. Polluted groundwater is characterized by elevated nitrate and sulfate concentrations and is usually derived from urban water cycling and subordinately from agricultural return flow. Mixed groundwaters between cold and hydrothermal components are predominantly found in the lower Atemajac Valley. Twenty-seven groundwater samples contain at least a small fraction of modern water. The application of a multivariate mixing model allowed the mixing proportions of hydrothermal fluids, polluted waters and cold groundwater in sampled water to be evaluated. This study will help local water authorities to identify and dimension groundwater contamination, and act accordingly. It may be broadly applicable to
Very deep hole concept. Thermal effects on groundwater flow
Energy Technology Data Exchange (ETDEWEB)
Marsic, Niko; Grundfelt, Bertil; Wiborgh, Marie [Kemakta Konsult AB, Stockholm (Sweden)
2006-09-15
,055 nodes. The results of the calculations were evaluated using tracking of particle starting in different positions in the deposition holes. The travel times for these particles to the surface were calculated. The particle tracking was performed for individual time steps assuming that the conditions of that time step remained constant throughout the particle travel times. This is of course not true, in particular as the calculated travel times are much longer that the duration of the heat pulse from the deposited spent fuel. A more refined variant of the grid including 1,245,680 finite elements corresponding to 2,525,744 nodes was tested in order to verify that the discretisation used was adequate. In this case, all elements inside the repository area and those closest to this area were refined by a factor of two in each of the three dimensions. The elements constituting the boreholes were left unchanged. The results of this test show that both the flow pattern and the calculated Darcy velocities are significantly affected by the disretisation while the calculated particle travel times were little influenced. Because of the little difference of travel times and due to the fact that the computational times of the larger grid were hard to manage within a reasonable project schedule, it was decided to use the smaller grid for the calculations. A large number of calculations were performed in which the sensitivity of the results with respect to different combinations of surface hydraulic gradients, heat output from the deposited spent fuel and fracture zone orientations was tested. In general, the calculated travel times for the particles are extremely long, in the order of 1-100 Myrs. The thermal output from the spent fuel is insufficient to alter the stability of the near-stagnant saline groundwater present at depth in the rock. However, the performed sensitivity analysis showed effects on the Darcy velocities, flow field and calculated hypothetical travel times, but the
Very deep hole concept. Thermal effects on groundwater flow
International Nuclear Information System (INIS)
Marsic, Niko; Grundfelt, Bertil; Wiborgh, Marie
2006-09-01
results of the calculations were evaluated using tracking of particle starting in different positions in the deposition holes. The travel times for these particles to the surface were calculated. The particle tracking was performed for individual time steps assuming that the conditions of that time step remained constant throughout the particle travel times. This is of course not true, in particular as the calculated travel times are much longer that the duration of the heat pulse from the deposited spent fuel. A more refined variant of the grid including 1,245,680 finite elements corresponding to 2,525,744 nodes was tested in order to verify that the discretisation used was adequate. In this case, all elements inside the repository area and those closest to this area were refined by a factor of two in each of the three dimensions. The elements constituting the boreholes were left unchanged. The results of this test show that both the flow pattern and the calculated Darcy velocities are significantly affected by the disretisation while the calculated particle travel times were little influenced. Because of the little difference of travel times and due to the fact that the computational times of the larger grid were hard to manage within a reasonable project schedule, it was decided to use the smaller grid for the calculations. A large number of calculations were performed in which the sensitivity of the results with respect to different combinations of surface hydraulic gradients, heat output from the deposited spent fuel and fracture zone orientations was tested. In general, the calculated travel times for the particles are extremely long, in the order of 1-100 Myrs. The thermal output from the spent fuel is insufficient to alter the stability of the near-stagnant saline groundwater present at depth in the rock. However, the performed sensitivity analysis showed effects on the Darcy velocities, flow field and calculated hypothetical travel times, but the differences do
Uncertainty in simulated groundwater-quality trends in transient flow
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.
An Analysis of Vehicular Traffic Flow Using Langevin Equation
Directory of Open Access Journals (Sweden)
Çağlar Koşun
2015-08-01
Full Text Available Traffic flow data are stochastic in nature, and an abundance of literature exists thereof. One way to express stochastic data is the Langevin equation. Langevin equation consists of two parts. The first part is known as the deterministic drift term, the other as the stochastic diffusion term. Langevin equation does not only help derive the deterministic and random terms of the selected portion of the city of Istanbul traffic empirically, but also sheds light on the underlying dynamics of the flow. Drift diagrams have shown that slow lane tends to get congested faster when vehicle speeds attain a value of 25 km/h, and it is 20 km/h for the fast lane. Three or four distinct regimes may be discriminated again from the drift diagrams; congested, intermediate, and free-flow regimes. At places, even the intermediate regime may be divided in two, often with readiness to congestion. This has revealed the fact that for the selected portion of the highway, there are two main states of flow, namely, congestion and free-flow, with an intermediate state where the noise-driven traffic flow forces the flow into either of the distinct regimes.
On the Eikonal equation in the pedestrian flow problem
Felcman, J.; Kubera, P.
2017-07-01
We consider the Pedestrian Flow Equations (PFEs) as the coupled system formed by the Eikonal equation and the first order hyperbolic system with the source term. The hyperbolic system consists of the continuity equation and momentum equation of fluid dynamics. Specifying the social and pressure forces in the momentum equation we come to the assumption that each pedestrian is trying to move in a desired direction (e.g. to the exit in the panic situation) with a desired velocity, where his velocity and the direction of movement depend on the density of pedestrians in his neighborhood. In [1] we used the model, where the desired direction of movement is given by the solution of the Eikonal equation (more precisely by the gradient of the solution). Here we avoid the solution of the Eikonal equation, which is the novelty of the paper. Based on the fact that the solution of the Eikonal equation has the meaning of the shortest time to reach the exit, we define explicitly such a function in the framework of the Dijkstra's algorithm for the shortest path in the graph. This is done at the discrete level of the solution. As the graph we use the underlying triangulation, where the norm of each edge is density depending and has the dimension of the time. The numerical examples of the solution of the PFEs with and without the solution of the Eikonal equation are presented.
First status report on regional ground-water flow modeling for the Paradox Basin, Utah
International Nuclear Information System (INIS)
Andrews, R.W.
1984-05-01
Regional ground-water flow within the principal hydrogeologic units of the Paradox Basin is evaluated by developing a conceptual model of the flow regime in the shallow aquifers and the deep-basin brine aquifers and testing these models using a three-dimensional, finite-difference flow code. Semiquantitative sensitivity analysis (a limited parametric study) is conducted to define the system response to changes in hydrologic properties or boundary conditions. A direct method for sensitivity analysis using an adjoint form of the flow equation is applied to the conceptualized flow regime in the Leadville limestone aquifer. All steps leading to the final results and conclusions are incorporated in this report. The available data utilized in this study is summarized. The specific conceptual models, defining the areal and vertical averaging of litho-logic units, aquifer properties, fluid properties, and hydrologic boundary conditions, are described in detail. Two models were evaluated in this study: a regional model encompassing the hydrogeologic units above and below the Paradox Formation/Hermosa Group and a refined scale model which incorporated only the post Paradox strata. The results are delineated by the simulated potentiometric surfaces and tables summarizing areal and vertical boundary fluxes, Darcy velocities at specific points, and ground-water travel paths. Results from the adjoint sensitivity analysis include importance functions and sensitivity coefficients, using heads or the average Darcy velocities to represent system response. The reported work is the first stage of an ongoing evaluation of the Gibson Dome area within the Paradox Basin as a potential repository for high-level radioactive wastes
Relation of streams, lakes, and wetlands to groundwater flow systems
Winter, Thomas C.
Surface-water bodies are integral parts of groundwater flow systems. Groundwater interacts with surface water in nearly all landscapes, ranging from small streams, lakes, and wetlands in headwater areas to major river valleys and seacoasts. Although it generally is assumed that topographically high areas are groundwater recharge areas and topographically low areas are groundwater discharge areas, this is true primarily for regional flow systems. The superposition of local flow systems associated with surface-water bodies on this regional framework results in complex interactions between groundwater and surface water in all landscapes, regardless of regional topographic position. Hydrologic processes associated with the surface-water bodies themselves, such as seasonally high surface-water levels and evaporation and transpiration of groundwater from around the perimeter of surface-water bodies, are a major cause of the complex and seasonally dynamic groundwater flow fields associated with surface water. These processes have been documented at research sites in glacial, dune, coastal, mantled karst, and riverine terrains. Résumé Les eaux de surface sont parties intégrantes des systèmes aquifères. Les eaux souterraines interagissent avec les eaux de surface dans presque tous les types d'environnements, depuis les petits ruisseaux, les lacs et les zones humides jusqu'aux bassins versants des vallées des grands fleuves et aux lignes de côte. Il est en général admis que les zones topographiquement hautes sont des lieux de recharge des aquifères et les zones basses des lieux de décharge, ce qui est le cas des grands systèmes aquifères régionaux. La superposition de systèmes locaux, associés à des eaux de surface, à l'organisation régionale d'écoulements souterrains résulte d'interactions complexes entre les eaux souterraines et les eaux de surface dans tous les environnements, quelle que soit la situation topographique régionale. Les processus
Weyer, K. U.
2017-12-01
Coastal groundwater flow investigations at the Biscayne Bay, south of Miami, Florida, gave rise to the concept of density-driven flow of seawater into coastal aquifers creating a saltwater wedge. Within that wedge, convection-driven return flow of seawater and a dispersion zone were assumed by Cooper et al. (1964) to be the cause of the Biscayne aquifer `sea water wedge'. This conclusion was based on the chloride distribution within the aquifer and on an analytical model concept assuming convection flow within a confined aquifer without taking non-chemical field data into consideration. This concept was later labelled the `Henry Problem', which any numerical variable density flow program must be able to simulate to be considered acceptable. Both, `density-driven flow' and Tothian `groundwater flow systems' (with or without variable density conditions) are driven by gravitation. The difference between the two are the boundary conditions. 'Density-driven flow' occurs under hydrostatic boundary conditions while Tothian `groundwater flow systems' occur under hydrodynamic boundary conditions. Revisiting the Cooper et al. (1964) publication with its record of piezometric field data (heads) showed that the so-called sea water wedge has been caused by discharging deep saline groundwater driven by gravitational flow and not by denser sea water. Density driven flow of seawater into the aquifer was not found reflected in the head measurements for low and high tide conditions which had been taken contemporaneously with the chloride measurements. These head measurements had not been included in the flow interpretation. The very same head measurements indicated a clear dividing line between shallow local fresh groundwater flow and saline deep groundwater flow without the existence of a dispersion zone or a convection cell. The Biscayne situation emphasizes the need for any chemical interpretation of flow pattern to be supported by head data as energy indicators of flow fields
Flow equation, conformal symmetry, and anti-de Sitter geometry
Aoki, Sinya; Yokoyama, Shuichi
2018-03-01
We argue that the anti-de Sitter (AdS) geometry in d+1 dimensions naturally emerges from an arbitrary conformal field theory in d dimensions using the free flow equation. We first show that an induced metric defined from the flowed field generally corresponds to the quantum information metric, called the Bures or Helstrom metric, if the flowed field is normalized appropriately. We next verify that the induced metric computed explicitly with the free flow equation always becomes the AdS metric when the theory is conformal. We finally prove that the conformal symmetry in d dimensions converts to the AdS isometry in d+1 dimensions after d-dimensional quantum averaging. This guarantees the emergence of AdS geometry without explicit calculation.
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.
Effect of irrigation return flow on groundwater recharge in an overexploited aquifer in Bangladesh
Touhidul Mustafa, Syed Md.; Shamsudduha, Mohammad; Huysmans, Marijke
2016-04-01
Irrigated agriculture has an important role in the food production to ensure food security of Bangladesh that is home to over 150 million people. However, overexploitation of groundwater for irrigation, particularly during the dry season, causes groundwater-level decline in areas where abstraction is high and surface geology inhibits direct recharge to underlying shallow aquifer. This is causing a number of potential adverse socio-economic, hydrogeological, and environmental problems in Bangladesh. Alluvial aquifers are primarily recharged during monsoon season from rainfall and surface sources. However, return flow from groundwater-fed irrigation can recharge during the dry months. Quantification of the effect of return flow from irrigation in the groundwater system is currently unclear but thought to be important to ensure sustainable management of the overexploited aquifer. The objective of the study is to investigate the effect of irrigation return flow on groundwater recharge in the north-western part of Bangladesh, also known as Barind Tract. A semi-physically based distributed water balance model (WetSpass-M) is used to simulate spatially distributed monthly groundwater recharge. Results show that, groundwater abstraction for irrigation in the study area has increased steadily over the last 29 years. During the monsoon season, local precipitation is the controlling factor of groundwater recharge; however, there is no trend in groundwater recharge during that period. During the dry season, however, irrigation return-flow plays a major role in recharging the aquifer in the irrigated area compared to local precipitation. Therefore, during the dry season, mean seasonal groundwater recharge has increased and almost doubled over the last 29 years as a result of increased abstraction for irrigation. The increase in groundwater recharge during dry season has however no significant effect in the improvement of groundwater levels. The relation between groundwater
International Nuclear Information System (INIS)
Onoe, Hironori; Saegusa, Hiromitsu; Takeuchi, Ryuji
2016-01-01
This paper comprehensively describes the result of groundwater flow modeling using data of hydraulic responses due to construction of Mizunami Underground Research Laboratory (MIU) in Mizunami, Gifu, in order to update hydrogeological model based on stepwise approach for crystalline fractured rock in Japan. The results showed that large scale hydraulic compartment structures which has significant influence on change of groundwater flow characteristics are distributed around MIU. Furthermore, it is concluded that hydrogeological monitoring data and groundwater flow modeling during construction of deep underground facilities are effective for hydrogeological characterization of heterogeneous fractured rock. (author)
Structural Control and Groundwater Flow in the Nubian Aquifer
Fathy, K.; Sultan, M.; Ahmed, M.; Save, H.; Emil, M. K.; Elkaliouby, B.
2017-12-01
An integrated research approach (remote sensing, field, geophysics) was conducted to investigate the structural control on groundwater flow in large aquifers using the less studied Nubian Sandstone Aquifer System (NSAS) of NE Africa as a test site. The aquifer extends over 2.2 x 106 km2 in Egypt, Libya, Chad, and Sudan and consists of thick (> 3 kms), water-bearing, Paleozoic and Mesozoic sandstone with intercalations of Tertiary shale and clay. It is subdivided into three sub-basins (Northern Sudan Platform [NSP], Dakhla [DAS], and Kufra) that are separated by basement uplifts (e.g., E-W trending Uweinat-Aswan uplift that separates DAS from the NSP). Aquifer recharge occurs in the south (NSP and southern Kufra) where the aquifer is unconfined and precipitation is high (Average Annual Precipitation [AAP]: 117 mm/yr.) and discharge is concentrated in the north (DAS and northern Kufra). Our approach is a three-fold exercise. Firstly, we compared GOCE-based Global Geopotential Models (GGMs) to terrestrial gravity anomalies for 21262 sites to select the optimum model for deriving Bouguer gravity anomalies. Secondly, structures and uplifts were mapped using hill shade images and their extension in the subsurface were mapped using the Eigen_6C4 model-derived Bouguer anomalies and their Tilt Derivative products (TDR). Thirdly, hydrological analysis was conducted using GRACE CSR 1° x 1° mascon solutions to investigate the mass variations in relation to the mapped structures. Our findings include: (1) The Eigen-6C4 is the optimum model having the lowest deviation (9.122 mGal) from the terrestrial gravity anomalies; (2) the surface expressions of structures matched fairly well with their postulated extensions in the subsurface; (3) identified fault systems include: Red Sea rift-related N-S to NW-SE trending grabens formed by reactivating basement structures during Red Sea opening and Syrian arc-related NE-SW trending dextral shear systems; (4) TWS patterns are uniform
Groundwater flow system under a rapidly urbanizing coastal city as determined by hydrogeochemistry
Kagabu, Makoto; Shimada, Jun; Delinom, Robert; Tsujimura, Maki; Taniguchi, Makoto
2011-01-01
In the Jakarta area (Indonesia), excessive groundwater pumping due to the rapidly increasing population has caused groundwater-related problems such as brackish water contamination in coastal areas and land subsidence. In this study, we adopted multiple hydrogeochemical techniques to demonstrate the groundwater flow system in the Jakarta area. Although almost all groundwater existing in the Jakarta basin is recharged at similar elevations, the water quality and residence time demonstrates a clear difference between the shallow and deep aquifers. Due to the rapid decrease in the groundwater potential in urban areas, we found that the seawater intrusion and the shallow and deep groundwaters are mixing, a conclusion confirmed by major ions, Br -:Cl - ratios, and chlorofluorocarbon (CFC)-12 analysis. Spring water and groundwater samples collected from the southern mountainside area show younger age characteristics with high concentrations of 14C and Ca-HCO 3 type water chemistry. We estimated the residence times of these groundwaters within 45 years under piston flow conditions by tritium analysis. Also, these groundwater ages can be limited to 20-30 years with piston flow evaluated by CFCs. Moreover, due to the magnitude of the CFC-12 concentration, we can use a pseudo age indicator in this field study, because we found a positive correlation between the major type of water chemistry and the CFC-12 concentration.
Using 14C and 3H to understand groundwater flow and recharge in an aquifer window
Atkinson, A. P.; Cartwright, I.; Gilfedder, B. S.; Cendón, D. I.; Unland, N. P.; Hofmann, H.
2014-12-01
Knowledge of groundwater residence times and recharge locations is vital to the sustainable management of groundwater resources. Here we investigate groundwater residence times and patterns of recharge in the Gellibrand Valley, southeast Australia, where outcropping aquifer sediments of the Eastern View Formation form an "aquifer window" that may receive diffuse recharge from rainfall and recharge from the Gellibrand River. To determine recharge patterns and groundwater flow paths, environmental isotopes (3H, 14C, δ13C, δ18O, δ2H) are used in conjunction with groundwater geochemistry and continuous monitoring of groundwater elevation and electrical conductivity. The water table fluctuates by 0.9 to 3.7 m annually, implying recharge rates of 90 and 372 mm yr-1. However, residence times of shallow (11 to 29 m) groundwater determined by 14C are between 100 and 10 000 years, 3H activities are negligible in most of the groundwater, and groundwater electrical conductivity remains constant over the period of study. Deeper groundwater with older 14C ages has lower δ18O values than younger, shallower groundwater, which is consistent with it being derived from greater altitudes. The combined geochemistry data indicate that local recharge from precipitation within the valley occurs through the aquifer window, however much of the groundwater in the Gellibrand Valley predominantly originates from the regional recharge zone, the Barongarook High. The Gellibrand Valley is a regional discharge zone with upward head gradients that limits local recharge to the upper 10 m of the aquifer. Additionally, the groundwater head gradients adjacent to the Gellibrand River are generally upwards, implying that it does not recharge the surrounding groundwater and has limited bank storage. 14C ages and Cl concentrations are well correlated and Cl concentrations may be used to provide a first-order estimate of groundwater residence times. Progressively lower chloride concentrations from 10
Equations for transient flow-boiling in a duct
International Nuclear Information System (INIS)
Mathers, W.G.; Ferch, R.L.; Hancox, W.T.; McDonald, B.H.
1981-01-01
In this paper we derive a separated phase model for weakly coupled flows which extends a model presented elsewhere (BANERJEE, FERCH, MATHERS and McDONALD, 1978). A hyperbolic system of seven partial differential equations results with ensemble-averaged phase velocities, enthalpies and pressures, and void fraction as dependent variables (UVUTUP model). The required constitutive equations for mass, momentum and energy transfer between phases and between the phases and the boundaries are discussed. The relationship of the UVUTUP model to other existing models is also presented
Groundwater flow modeling focused on the Fukushima Daiichi Nuclear Power Plant Site
International Nuclear Information System (INIS)
Saegusa, Hiromitsu; Onoe, Hironori; Kohashi, Akio; Watanabe, Masahisa
2015-01-01
Fukushima Daiichi nuclear power plant of Tokyo Electric Power Company is facing contaminated water issues in the aftermath of the Great East Japan Earthquake on March 11, 2011. The amount of contaminated water is continuously increasing due to groundwater leakage into the underground part of reactor and turbine buildings. Therefore, it is important to understand the groundwater flow conditions at the site and to predict the impact of countermeasures taken for isolating groundwater from the source of the contamination, i.e. the reactor buildings. Installations, such as of land-side and sea-side impermeable walls have been planned as countermeasures. In this study, groundwater flow modeling has been performed to estimate the response of groundwater flow conditions to the countermeasures. From the modeling, groundwater recharge and discharge areas, major groundwater flow direction, inflow rate into underground part of the buildings, and changes in response to implementation of the countermeasures could be reasonably estimated. The results indicate that the countermeasures will decrease the volume of inflow into the underground part of the buildings. This means that the countermeasures will be effective in reducing the discharge volume of contaminated groundwater to ocean. (author)
Groundwater flow and hydrogeochemical evolution in the Jianghan Plain, central China
Gan, Yiqun; Zhao, Ke; Deng, Yamin; Liang, Xing; Ma, Teng; Wang, Yanxin
2018-05-01
Hydrogeochemical analysis and multivariate statistics were applied to identify flow patterns and major processes controlling the hydrogeochemistry of groundwater in the Jianghan Plain, which is located in central Yangtze River Basin (central China) and characterized by intensive surface-water/groundwater interaction. Although HCO3-Ca-(Mg) type water predominated in the study area, the 457 (21 surface water and 436 groundwater) samples were effectively classified into five clusters by hierarchical cluster analysis. The hydrochemical variations among these clusters were governed by three factors from factor analysis. Major components (e.g., Ca, Mg and HCO3) in surface water and groundwater originated from carbonate and silicate weathering (factor 1). Redox conditions (factor 2) influenced the geogenic Fe and As contamination in shallow confined groundwater. Anthropogenic activities (factor 3) primarily caused high levels of Cl and SO4 in surface water and phreatic groundwater. Furthermore, the factor score 1 of samples in the shallow confined aquifer gradually increased along the flow paths. This study demonstrates that enhanced information on hydrochemistry in complex groundwater flow systems, by multivariate statistical methods, improves the understanding of groundwater flow and hydrogeochemical evolution due to natural and anthropogenic impacts.
International Nuclear Information System (INIS)
Davisson, M.L.; Criss, R.E.
1995-01-01
Intensive agricultural irrigation and overdraft of groundwater in the Central Valley of California profoundly affect the regional quality and availability of shallow groundwater resources. In the natural state, the δ 18 O values of groundwater were relatively homogeneous (mostly -7.0 ± 0.5 per-thousand), reflecting local meteoric recharge that slowly (1-3m/yr) flowed toward the valley axis. Today, on the west side of the valley, the isotope distribution is dominated by high 18 O enclosures formed by recharge of evaporated irrigation waters, while the east side has bands of low 18 O groundwater indicating induced recharge from rivers draining the Sierra Nevada mountains. Changes in δ 18 O values caused by the agricultural recharge strongly correlate with elevated nitrate concentrations (5 to >100 mg/L) that form pervasive, non-point source pollutants. Small, west-side cities dependent solely on groundwater resources have experienced increases of >1.0 mg/L per year of nitrate for 10-30 years. The resultant high nitrates threaten the economical use of the groundwater for domestic purposes, and have forced some well shut-downs. Furthermore, since >80% of modern recharge is now derived from agricultural irrigation, and because modern recharge rates are ∼10 times those of the natural state, agricultural land retirement by urbanization will severely curtail the current safe-yields and promote overdraft pumping. Such overdrafting has occurred in the Sacramento metropolitan area for ∼40 years, creating cones of depression ∼25m deep. Today, groundwater withdrawal in Sacramento is approximately matched by infiltration of low 18 O water (-11.0 per-thousand) away from the Sacramento and American Rivers, which is estimated to occur at 100-300m/year from the sharp 18 O gradients in our groundwater isotope map
Constitutive Equation with Varying Parameters for Superplastic Flow Behavior
Guan, Zhiping; Ren, Mingwen; Jia, Hongjie; Zhao, Po; Ma, Pinkui
2014-03-01
In this study, constitutive equations for superplastic materials with an extra large elongation were investigated through mechanical analysis. From the view of phenomenology, firstly, some traditional empirical constitutive relations were standardized by restricting some strain paths and parameter conditions, and the coefficients in these relations were strictly given new mechanical definitions. Subsequently, a new, general constitutive equation with varying parameters was theoretically deduced based on the general mechanical equation of state. The superplastic tension test data of Zn-5%Al alloy at 340 °C under strain rates, velocities, and loads were employed for building a new constitutive equation and examining its validity. Analysis results indicated that the constitutive equation with varying parameters could characterize superplastic flow behavior in practical superplastic forming with high prediction accuracy and without any restriction of strain path or deformation condition, showing good industrial or scientific interest. On the contrary, those empirical equations have low prediction capabilities due to constant parameters and poor applicability because of the limit of special strain path or parameter conditions based on strict phenomenology.
Accurate and efficient calculation of response times for groundwater flow
Carr, Elliot J.; Simpson, Matthew J.
2018-03-01
We study measures of the amount of time required for transient flow in heterogeneous porous media to effectively reach steady state, also known as the response time. Here, we develop a new approach that extends the concept of mean action time. Previous applications of the theory of mean action time to estimate the response time use the first two central moments of the probability density function associated with the transition from the initial condition, at t = 0, to the steady state condition that arises in the long time limit, as t → ∞ . This previous approach leads to a computationally convenient estimation of the response time, but the accuracy can be poor. Here, we outline a powerful extension using the first k raw moments, showing how to produce an extremely accurate estimate by making use of asymptotic properties of the cumulative distribution function. Results are validated using an existing laboratory-scale data set describing flow in a homogeneous porous medium. In addition, we demonstrate how the results also apply to flow in heterogeneous porous media. Overall, the new method is: (i) extremely accurate; and (ii) computationally inexpensive. In fact, the computational cost of the new method is orders of magnitude less than the computational effort required to study the response time by solving the transient flow equation. Furthermore, the approach provides a rigorous mathematical connection with the heuristic argument that the response time for flow in a homogeneous porous medium is proportional to L2 / D , where L is a relevant length scale, and D is the aquifer diffusivity. Here, we extend such heuristic arguments by providing a clear mathematical definition of the proportionality constant.
Groundwater flow through a natural fracture. Flow experiments and numerical modelling
Energy Technology Data Exchange (ETDEWEB)
Larsson, Erik [Chalmers Univ. of Technology, Goeteborg (Sweden). Dept of Geology
1997-09-01
Groundwater flow and transport play an important role not only for groundwater exploration but also in environmental engineering problems. This report considers how the hydraulic properties of fractures in crystalline rock depend on the fracture aperture geometry. Different numerical models are discussed and a FDM computer code for two- and three- dimensional flow-modelling has been developed. Different relations between the cells in the model are tested and compared with results in the literature. A laboratory experimental work has been done to carry out flow experiments and aperture measurements on the same specimen of a natural fracture. The drilled core sample had fractures parallel to the core axis and was placed inside a biaxial cell during the experiments. The water pressure gradient and the compression stress were varied during the experiments and also a tracer test was done. After the flow experiments, the aperture distribution for a certain compression was measured by injecting an epoxy resin into the fracture. The thickness of the resin layer was then studied in saw cut sections of the sample. The results from the experiments were used to validate numerical and analytical models, based on aperture distribution, for flow and transport simulations. In the disturbed zone around a drift both water and air are present in the fractures. The gas will go to the most wide part of the fracture because the capillarity and the conductivity decrease. The dependence of the effective conductivity on the variance of the conductivity and the effect of extinction of highly conductive cells has also been studied. A discussion of how gas in fractures around a drift can cause a skin effect is modelled and an example is given of what a saturation depending on the magnitude of the flow causes. 25 refs, 17 tabs, 43 figs.
Groundwater flow through a natural fracture. Flow experiments and numerical modelling
International Nuclear Information System (INIS)
Larsson, Erik
1997-09-01
Groundwater flow and transport play an important role not only for groundwater exploration but also in environmental engineering problems. This report considers how the hydraulic properties of fractures in crystalline rock depend on the fracture aperture geometry. Different numerical models are discussed and a FDM computer code for two- and three- dimensional flow-modelling has been developed. Different relations between the cells in the model are tested and compared with results in the literature. A laboratory experimental work has been done to carry out flow experiments and aperture measurements on the same specimen of a natural fracture. The drilled core sample had fractures parallel to the core axis and was placed inside a biaxial cell during the experiments. The water pressure gradient and the compression stress were varied during the experiments and also a tracer test was done. After the flow experiments, the aperture distribution for a certain compression was measured by injecting an epoxy resin into the fracture. The thickness of the resin layer was then studied in saw cut sections of the sample. The results from the experiments were used to validate numerical and analytical models, based on aperture distribution, for flow and transport simulations. In the disturbed zone around a drift both water and air are present in the fractures. The gas will go to the most wide part of the fracture because the capillarity and the conductivity decrease. The dependence of the effective conductivity on the variance of the conductivity and the effect of extinction of highly conductive cells has also been studied. A discussion of how gas in fractures around a drift can cause a skin effect is modelled and an example is given of what a saturation depending on the magnitude of the flow causes
Site-scale groundwater flow modelling of Beberg
Energy Technology Data Exchange (ETDEWEB)
Gylling, B. [Kemakta Konsult AB, Stockholm (Sweden); Walker, D. [Duke Engineering and Services (United States); Hartley, L. [AEA Technology, Harwell (United Kingdom)
1999-08-01
The Swedish Nuclear Fuel and Waste Management Company (SKB) Safety Report for 1997 (SR 97) study is a comprehensive performance assessment illustrating the results for three hypothetical repositories in Sweden. In support of SR 97, this study examines the hydrogeologic modelling of the hypothetical site called Beberg, which adopts input parameters from the SKB study site near Finnsjoen, in central Sweden. This study uses a nested modelling approach, with a deterministic regional model providing boundary conditions to a site-scale stochastic continuum model. The model is run in Monte Carlo fashion to propagate the variability of the hydraulic conductivity to the advective travel paths from representative canister positions. A series of variant cases addresses uncertainties in the inference of parameters and the boundary conditions. The study uses HYDRASTAR, the SKB stochastic continuum (SC) groundwater modelling program, to compute the heads, Darcy velocities at each representative canister position, and the advective travel times and paths through the geosphere. The Base Case simulation takes its constant head boundary conditions from a modified version of the deterministic regional scale model of Hartley et al. The flow balance between the regional and site-scale models suggests that the nested modelling conserves mass only in a general sense, and that the upscaling is only approximately valid. The results for 100 realisation of 120 starting positions, a flow porosity of {epsilon}{sub f} 10{sup -4}, and a flow-wetted surface of a{sub r} = 1.0 m{sup 2}/(m{sup 3} rock) suggest the following statistics for the Base Case: The median travel time is 56 years. The median canister flux is 1.2 x 10{sup -3} m/year. The median F-ratio is 5.6 x 10{sup 5} year/m. The travel times, flow paths and exit locations were compatible with the observations on site, approximate scoping calculations and the results of related modelling studies. Variability within realisations indicates
Site-scale groundwater flow modelling of Beberg
International Nuclear Information System (INIS)
Gylling, B.; Walker, D.; Hartley, L.
1999-08-01
The Swedish Nuclear Fuel and Waste Management Company (SKB) Safety Report for 1997 (SR 97) study is a comprehensive performance assessment illustrating the results for three hypothetical repositories in Sweden. In support of SR 97, this study examines the hydrogeologic modelling of the hypothetical site called Beberg, which adopts input parameters from the SKB study site near Finnsjoen, in central Sweden. This study uses a nested modelling approach, with a deterministic regional model providing boundary conditions to a site-scale stochastic continuum model. The model is run in Monte Carlo fashion to propagate the variability of the hydraulic conductivity to the advective travel paths from representative canister positions. A series of variant cases addresses uncertainties in the inference of parameters and the boundary conditions. The study uses HYDRASTAR, the SKB stochastic continuum (SC) groundwater modelling program, to compute the heads, Darcy velocities at each representative canister position, and the advective travel times and paths through the geosphere. The Base Case simulation takes its constant head boundary conditions from a modified version of the deterministic regional scale model of Hartley et al. The flow balance between the regional and site-scale models suggests that the nested modelling conserves mass only in a general sense, and that the upscaling is only approximately valid. The results for 100 realisation of 120 starting positions, a flow porosity of ε f 10 -4 , and a flow-wetted surface of a r = 1.0 m 2 /(m 3 rock) suggest the following statistics for the Base Case: The median travel time is 56 years. The median canister flux is 1.2 x 10 -3 m/year. The median F-ratio is 5.6 x 10 5 year/m. The travel times, flow paths and exit locations were compatible with the observations on site, approximate scoping calculations and the results of related modelling studies. Variability within realisations indicates that the change in hydraulic gradient
Kuniansky, Eve L.
2016-09-22
Understanding karst aquifers, for purposes of their management and protection, poses unique challenges. Karst aquifers are characterized by groundwater flow through conduits (tertiary porosity), and (or) layers with interconnected pores (secondary porosity) and through intergranular porosity (primary or matrix porosity). Since the late 1960s, advances have been made in the development of numerical computer codes and the use of mathematical model applications towards the understanding of dual (primary [matrix] and secondary [fractures and conduits]) porosity groundwater flow processes, as well as characterization and management of karst aquifers. The Floridan aquifer system (FAS) in Florida and parts of Alabama, Georgia, and South Carolina is composed of a thick sequence of predominantly carbonate rocks. Karst features are present over much of its area, especially in Florida where more than 30 first-magnitude springs occur, numerous sinkholes and submerged conduits have been mapped, and numerous circular lakes within sinkhole depressions are present. Different types of mathematical models have been applied for simulation of the FAS. Most of these models are distributed parameter models based on the assumption that, like a sponge, water flows through connected pores within the aquifer system and can be simulated with the same mathematical methods applied to flow through sand and gravel aquifers; these models are usually referred to as porous-equivalent media models. The partial differential equation solved for groundwater flow is the potential flow equation of fluid mechanics, which is used when flow is dominated by potential energy and has been applied for many fluid problems in which kinetic energy terms are dropped from the differential equation solved. In many groundwater model codes (basic MODFLOW), it is assumed that the water has a constant temperature and density and that flow is laminar, such that kinetic energy has minimal impact on flow. Some models have
Guide to the Revised Ground-Water Flow and Heat Transport Simulator: HYDROTHERM - Version 3
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
Leighton, David A.; Phillips, Steven P.
2003-01-01
Antelope Valley, California, is a topographically closed basin in the western part of the Mojave Desert, about 50 miles northeast of Los Angeles. The Antelope Valley ground-water basin is about 940 square miles and is separated from the northern part of Antelope Valley by faults and low-lying hills. Prior to 1972, ground water provided more than 90 percent of the total water supply in the valley; since 1972, it has provided between 50 and 90 percent. Most ground-water pumping in the valley occurs in the Antelope Valley ground-water basin, which includes the rapidly growing cities of Lancaster and Palmdale. Ground-water-level declines of more than 200 feet in some parts of the ground-water basin have resulted in an increase in pumping lifts, reduced well efficiency, and land subsidence of more than 6 feet in some areas. Future urban growth and limits on the supply of imported water may continue to increase reliance on ground water. To better understand the ground-water flow system and to develop a tool to aid in effectively managing the water resources, a numerical model of ground-water flow and land subsidence in the Antelope Valley ground-water basin was developed using old and new geohydrologic information. The ground-water flow system consists of three aquifers: the upper, middle, and lower aquifers. The aquifers, which were identified on the basis of the hydrologic properties, age, and depth of the unconsolidated deposits, consist of gravel, sand, silt, and clay alluvial deposits and clay and silty clay lacustrine deposits. Prior to ground-water development in the valley, recharge was primarily the infiltration of runoff from the surrounding mountains. Ground water flowed from the recharge areas to discharge areas around the playas where it discharged either from the aquifer system as evapotranspiration or from springs. Partial barriers to horizontal ground-water flow, such as faults, have been identified in the ground-water basin. Water-level declines owing to
Controls on groundwater flow in the Bengal Basin of India and Bangladesh: regional modeling analysis
Michael, Holly A.; Voss, Clifford I.
2009-11-01
Groundwater for domestic and irrigation purposes is produced primarily from shallow parts of the Bengal Basin aquifer system (India and Bangladesh), which contains high concentrations of dissolved arsenic (exceeding worldwide drinking water standards), though deeper groundwater is generally low in arsenic. An essential first step for determining sustainable management of the deep groundwater resource is identification of hydrogeologic controls on flow and quantification of basin-scale groundwater flow patterns. Results from groundwater modeling, in which the Bengal Basin aquifer system is represented as a single aquifer with higher horizontal than vertical hydraulic conductivity, indicate that this anisotropy is the primary hydrogeologic control on the natural flowpath lengths. Despite extremely low hydraulic gradients due to minimal topographic relief, anisotropy implies large-scale (tens to hundreds of kilometers) flow at depth. Other hydrogeologic factors, including lateral and vertical changes in hydraulic conductivity, have minor effects on overall flow patterns. However, because natural hydraulic gradients are low, the impact of pumping on groundwater flow is overwhelming; modeling indicates that pumping has substantially changed the shallow groundwater budget and flowpaths from predevelopment conditions.
Arrangement of disposal holes according to the features of groundwater flow
Energy Technology Data Exchange (ETDEWEB)
Ko, Nak Youl; Baik, Min Hoon [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)
2016-12-15
Based on the results of groundwater flow system modeling for a hypothetical deep geological repository site, quantitative and spatial distributions of groundwater flow rates at the positions of deposition holes, groundwater travel length and time from the positions to the surface environment were analyzed and used to suggest a method for determining locations of deposition holes. The hydraulic head values at the depth of the deposition holes and a particle tracking method were used to calculate the groundwater flow rates and groundwater travel length and time, respectively. From the results, an approach to designing a layout of deposition holes was suggested by selecting relatively favorable positions for maintaining performance of the disposal facility and screening some positions of deposition holes that did not comply with specific constraints for the groundwater flow rates, travel length and time. In addition, a method for determining a geometrical direction for extension of the disposal facility was discussed. Designing the layout of deposition holes with the information of groundwater flow at the disposal depth can contribute to secure performance and safety of the disposal facility.
Controls on groundwater flow in the Bengal Basin of India and Bangladesh: Regional modeling analysis
Michael, H.A.; Voss, C.I.
2009-01-01
Groundwater for domestic and irrigation purposes is produced primarily from shallow parts of the Bengal Basin aquifer system (India and Bangladesh), which contains high concentrations of dissolved arsenic (exceeding worldwide drinking water standards), though deeper groundwater is generally low in arsenic. An essential first step for determining sustainable management of the deep groundwater resource is identification of hydrogeologic controls on flow and quantification of basin-scale groundwater flow patterns. Results from groundwater modeling, in which the Bengal Basin aquifer system is represented as a single aquifer with higher horizontal than vertical hydraulic conductivity, indicate that this anisotropy is the primary hydrogeologic control on the natural flowpath lengths. Despite extremely low hydraulic gradients due to minimal topographic relief, anisotropy implies large-scale (tens to hundreds of kilometers) flow at depth. Other hydrogeologic factors, including lateral and vertical changes in hydraulic conductivity, have minor effects on overall flow patterns. However, because natural hydraulic gradients are low, the impact of pumping on groundwater flow is overwhelming; modeling indicates that pumping has substantially changed the shallow groundwater budget and flowpaths from predevelopment conditions. ?? Springer-Verlag 2009.
Irregular conformal block, spectral curve and flow equations
International Nuclear Information System (INIS)
Choi, Sang Kwan; Rim, Chaiho; Zhang, Hong
2016-01-01
Irregular conformal block is motivated by the Argyres-Douglas type of N=2 super conformal gauge theory. We investigate the classical/NS limit of irregular conformal block using the spectral curve on a Riemann surface with irregular punctures, which is equivalent to the loop equation of irregular matrix model. The spectral curve is reduced to the second order (Virasoro symmetry, SU(2) for the gauge theory) and third order (W_3 symmetry, SU(3)) differential equations of a polynomial with finite degree. The conformal and W symmetry generate the flow equations in the spectral curve and determine the irregular conformal block, hence the partition function of the Argyres-Douglas theory ala AGT conjecture.
Improved coupling of the conduction and flow equations in TRAC
International Nuclear Information System (INIS)
Addessio, F.L.
1981-01-01
Recent nuclear-reactor-systems modeling efforts have been directed toward the development of computer codes capable of simulating transients in short computational times. For this reason, a stability enhancing two-stem method (SETS) has been applied to the two-phase flow equations in the Transient Reactor Analysis Code (TRAC) allowing the Courant limit to be violated. Unfortunately, the coupling between the wall conduction equation and the fluid-dynamics equations is performed semi-implicitly, that is, the wall-heat transfer term, is evaluated using old-time heat-transfer coefficients and wall temperatures and new-time coolant temperatures. This coupling may lead to numerical instabilities at large time steps because of large variations in the heat-transfer coefficient in certain regimes of the boiling curve. Consequently, simply using new-time wall temperatures is not sufficient. A technique that also incorporates new-time heat-transfer coefficients must be used
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...
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
Comparing groundwater recharge and base flow in the Bukmoongol ...
Indian Academy of Sciences (India)
Groundwater recharge and base ﬂow using different investigated methods are simulated in the 15-ha Bukmoongol small-forested watershed located at the southern part of Korea.The WHAT system, PART,RORA,PULSE,BFI,and RAP software are used to estimate groundwater recharge or base ﬂow and base ﬂow index from ...
The in situ permeable flow sensor: A device for measuring groundwater flow velocity
International Nuclear Information System (INIS)
Ballard, S.; Barker, G.T.; Nichols, R.L.
1994-03-01
A new technology called the In Situ Permeable Flow Sensor has been developed at Sandia National Laboratories. These sensors use a thermal perturbation technique to directly measure the direction and magnitude of the full three dimensional groundwater flow velocity vector in unconsolidated, saturated, porous media. The velocity measured is an average value characteristic of an approximately 1 cubic meter volume of the subsurface. During a test at the Savannah River Site in South Carolina, two flow sensors were deployed in a confined aquifer in close proximity to a well which was screened over the entire vertical extent of the aquifer and the well was pumped at four different pumping rates. In this situation horizontal flow which is radially directed toward the pumping well is expected. The flow sensors measured horizontal flow which was directed toward the pumping well, within the uncertainty in the measurements. The observed magnitude of the horizontal component of the flow velocity increased linearly with pumping rate, as predicted by theoretical considerations. The measured horizontal component of the flow velocity differed from the predicted flow velocity, which was calculated with the assumptions that the hydraulic properties of the aquifer were radially homogeneous and isotropic, by less than a factor of two. Drawdown data obtained from other wells near the pumping well during the pump test indicate that the hydraulic properties of the aquifer are probably not radially homogeneous but the effect of the inhomogeneity on the flow velocity field around the pumping well was not modeled because the degree and distribution of the inhomogeneity are unknown. Grain size analysis of core samples from wells in the area were used to estimate the vertical distribution of hydraulic conductivity
Perturbative renormalization of composite operators via flow equations. Pt. 2
International Nuclear Information System (INIS)
Keller, G.; Kopper, C.
1993-01-01
We give a rigorous and very detailed derivation of the short distance expansion for a product of two arbitrary composite operators in the framework of the perturbative Euclidean massive Φ 4 4 . The technically almost trivial proof rests on an extension of the differential flow equation method to Green functions with bilocal insertions, for which we also establish a set of generalized Zimmermann identities and Lowenstein rules. (orig.)
Ill-posedness of Dynamic Equations of Compressible Granular Flow
Shearer, Michael; Gray, Nico
2017-11-01
We introduce models for 2-dimensional time-dependent compressible flow of granular materials and suspensions, based on the rheology of Pouliquen and Forterre. The models include density dependence through a constitutive equation in which the density or volume fraction of solid particles with material density ρ* is taken as a function of an inertial number I: ρ = ρ * Φ(I), in which Φ(I) is a decreasing function of I. This modelling has different implications from models relying on critical state soil mechanics, in which ρ is treated as a variable in the equations, contributing to a flow rule. The analysis of the system of equations builds on recent work of Barker et al in the incompressible case. The main result is the identification of a criterion for well-posedness of the equations. We additionally analyze a modification that applies to suspensions, for which the rheology takes a different form and the inertial number reflects the role of the fluid viscosity.
Wairarapa Valley groundwater : residence time, flow pattern, and hydrochemistry trends
International Nuclear Information System (INIS)
Morgenstern, U.
2005-01-01
The Wairarapa groundwater system has a complicated hydrogeological setting as it evolved from sea level changes, tectonic activity, and geomorphic process. Due to increasing groundwater demand a better understanding of the groundwater resources is required to help achieve effective management and sustainable use. In addition to previous 'classical' hydrogeology studies, this report represents the first stage of a comprehensive approach using age dating and chemistry time trends for understanding the Wairarapa groundwater system. The methodology of groundwater age dating and mixing models is described in Appendix 1. Historic tritium data were evaluated, and combined with new tritium and CFC/SF 6 data to allow for robust age dating. (author). 14 refs., 30 figs
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.
Effects of Sea Level Rise on Groundwater Flow Paths in a Coastal Aquifer System
Morrissey, S. K.; Clark, J. F.; Bennett, M. W.; Richardson, E.; Stute, M.
2008-05-01
Changes in groundwater flow in the Floridan aquifer system, South Florida, from the rise in sea level at the end of the last glacial period may be indicative of changes coastal aquifers will experience with continued sea level rise. As sea level rises, the hydraulic head near the coast increases. Coastal aquifers can therefore experience decreased groundwater gradients (increased residence times) and seawater intrusion. Stable isotopes of water, dissolved noble gas temperatures, radiocarbon and He concentrations were analyzed in water collected from 68 wells in the Floridan aquifer system throughout South Florida. Near the recharge area, geochemical data along groundwater flow paths in the Upper Floridan aquifer show a transition from recently recharged groundwater to glacial-aged water. Down gradient from this transition, little variation is apparent in the stable isotopes and noble gas recharge temperatures, indicating that most of the Upper Floridan aquifer contains groundwater recharged during the last glacial period. The rapid 120-meter rise in sea level marking the end of the last glacial period increased the hydraulic head in the Floridan aquifer system near the coast, slowing the flow of groundwater from the recharge area to the ocean and trapping glacial-aged groundwater. The raised sea level also flooded half of the Florida platform and caused seawater to intrude into the Lower Floridan. This circulation of seawater in the Lower Floridan continues today as our data indicate that the groundwater is similar to modern seawater with a freshwater component entering vertically from the recharge area to the Upper Floridan.
Jones, Joseph L.; Johnson, Kenneth H.; Frans, Lonna M.
2016-08-18
Information about groundwater-flow paths and locations where groundwater discharges at and near Puget Sound Naval Shipyard is necessary for understanding the potential migration of subsurface contaminants by groundwater at the shipyard. The design of some remediation alternatives would be aided by knowledge of whether groundwater flowing at specific locations beneath the shipyard will eventually discharge directly to Sinclair Inlet of Puget Sound, or if it will discharge to the drainage system of one of the six dry docks located in the shipyard. A 1997 numerical (finite difference) groundwater-flow model of the shipyard and surrounding area was constructed to help evaluate the potential for groundwater discharge to Puget Sound. That steady-state, multilayer numerical model with homogeneous hydraulic characteristics indicated that groundwater flowing beneath nearly all of the shipyard discharges to the dry-dock drainage systems, and only shallow groundwater flowing beneath the western end of the shipyard discharges directly to Sinclair Inlet.Updated information from a 2016 regional groundwater-flow model constructed for the greater Kitsap Peninsula was used to update the 1997 groundwater model of the Puget Sound Naval Shipyard. That information included a new interpretation of the hydrogeologic units underlying the area, as well as improved recharge estimates. Other updates to the 1997 model included finer discretization of the finite-difference model grid into more layers, rows, and columns, all with reduced dimensions. This updated Puget Sound Naval Shipyard model was calibrated to 2001–2005 measured water levels, and hydraulic characteristics of the model layers representing different hydrogeologic units were estimated with the aid of state-of-the-art parameter optimization techniques.The flow directions and discharge locations predicted by this updated model generally match the 1997 model despite refinements and other changes. In the updated model, most
Faye, Robert E.; Jones, L. Elliott; Suárez-Soto, René J.
2013-01-01
This supplement of Chapter A (Supplement 3) summarizes results of analyses of groundwater-level data and describes corresponding elements of groundwater flow such as vertical hydraulic gradients useful for groundwater-flow model calibration. Field data as well as theoretical concepts indicate that potentiometric surfaces within the study area are shown to resemble to a large degree a subdued replica of surface topography. Consequently, precipitation that infiltrates to the water table flows laterally from highland to lowland areas and eventually discharges to streams such as Northeast and Wallace Creeks and New River. Vertically downward hydraulic gradients occur in highland areas resulting in the transfer of groundwater from shallow relatively unconfined aquifers to underlying confined or semi-confined aquifers. Conversely, in the vicinity of large streams such as Wallace and Frenchs Creeks, diffuse upward leakage occurs from underlying confined or semi-confined aquifers. Point water-level data indicating water-table altitudes, water-table altitudes estimated using a regression equation, and estimates of stream levels determined from a digital elevation model (DEM) and topographic maps were used to estimate a predevelopment water-table surface in the study area. Approximate flow lines along hydraulic gradients are shown on a predevelopment potentiometric surface map and extend from highland areas where potentiometric levels are greatest toward streams such as Wallace Creek and Northeast Creek. The distribution of potentiometric levels and corresponding groundwater-flow directions conform closely to related descriptions of the conceptual model.
Groundwater-flow modeling in the Yucatan karstic aquifer, Mexico
González-Herrera, Roger; Sánchez-y-Pinto, Ismael; Gamboa-Vargas, José
2002-09-01
The current conceptual model of the unconfined karstic aquifer in the Yucatan Peninsula, Mexico, is that a fresh-water lens floats above denser saline water that penetrates more than 40 km inland. The transmissivity of the aquifer is very high so the hydraulic gradient is very low, ranging from 7-10 mm/km through most of the northern part of the peninsula. The computer modeling program AQUIFER was used to investigate the regional groundwater flow in the aquifer. The karstified zone was modeled using the assumption that it acts hydraulically similar to a granular, porous medium. As part of the calibration, the following hypotheses were tested: (1) karstic features play an important role in the groundwater-flow system; (2) a ring or belt of sinkholes in the area is a manifestation of a zone of high transmissivity that facilitates the channeling of groundwater toward the Gulf of Mexico; and (3) the geologic features in the southern part of Yucatan influence the groundwater-flow system. The model shows that the Sierrita de Ticul fault, in the southwestern part of the study area, acts as a flow barrier and head values decline toward the northeast. The modeling also shows that the regional flow-system dynamics have not been altered despite the large number of pumping wells because the volume of water pumped is small compared with the volume of recharge, and the well-developed karst system of the region has a very high hydraulic conductivity. Résumé. Le modèle conceptuel classique de l'aquifère karstique libre de la péninsule du Yucatan (Mexique) consiste en une lentille d'eau douce flottant sur une eau salée plus dense qui pénètre à plus de 40 km à l'intérieur des terres. La transmissivité de l'aquifère est très élevée, en sorte que le gradient hydraulique est très faible, compris entre 7 et 10 mm/km dans la plus grande partie du nord de la péninsule. Le modèle AQUIFER a été utilisé pour explorer les écoulements souterrains régionaux dans cet
Simulating the effects of a beaver dam on regional groundwater flow through a wetland
Kathleen Feiner; Christopher S. Lowry
2015-01-01
Study Focus: This research examines a wetland environment before and after the construction of a beaver dam to determine the hydrologic impacts on regional groundwater flow and quantify changes to the capture zone of a wetland pond. Increased hydraulic head behind a newly built beaver dam can cause shifts in the capture zone of a wetland pond. Changes in groundwater flux, and the extent of both the capture and discharge zones of this wetland were examined with the use of a groundwater flow mo...
Modeling groundwater flow at the chemical plant area of the Weldon Spring Site
International Nuclear Information System (INIS)
Durham, L.A.
1992-10-01
Groundwater flow in the shallow unconfined aquifer at the chemical plant area of the Weldon Spring site, St. Charles County, Missouri, was modeled with the Coupled Fluid, Energy, and Solute Transport (CFEST) groundwater flow and contaminant transport computer code. The modeling was performed in support of a hydrogeological characterization effort that is part of the remedial investigation/feasibility study-environmental impact statement process being carried out by the US Department of Energy at the site. This report presents the results of model development and calibration. In the calibration procedure, the range of field-measured hydrogeological parameters was tested to obtain the best match between model-predicted and measured groundwater elevations. After calibration, the model was used to evaluate whether the presence of an on-site disposal cell would impact the ability to remediate contaminated groundwater beneath the cell. The results of the numerical modeling, which were based on an evaluation of steady-state groundwater flow velocity plots, indicated that groundwater would flow beneath the disposal cell along natural gradients. The presence of a disposal cell would not significantly affect remediation capability for groundwater contamination
Bowles, C. J.; Lawrence, R. L.; Noll, C.; Hancock, G. S.
2005-12-01
Channel incision is a widely observed response to increased flow in urbanized watersheds, but the effects of channel lowering on riparian water tables is not well documented. In a rapidly incising suburban stream in the Virginia Coastal Plain, we hypothesize that stream incision has lowered floodplain water tables and decreased the overbank flow frequency. The monitored stream is a tributary to the James River draining 1.3 km2 of which 15% is impervious cover. Incision has occurred largely through upstream migration of a one meter high knickpoint at a rate of ~1.5 m/yr, primarily during high flow events. We installed 63 wells in six stream-perpendicular transects as well as a cluster of wells around the knickpoint to assess water table elevations beneath the floodplain adjacent to the incising stream. Two transects are located 30 and 50 m upstream of the knickpoint in the unincised floodplain, and the remainder are 5, 30, 70, and 100 m downstream in the incised floodplain. In one transect above and two below, pressure transducers attached to dataloggers provide a high-resolution record of water table changes. Erosion pins were installed and channel cross-sections surveyed to determine streambed stability. Significant differences are observed in bank morphology and groundwater flow above vs. below the knickpoint. Above the knickpoint, the banks are stable, ~3 m wide, and ~0.3 m deep, and widen and deepen slightly toward the knickpoint. The water table is relatively flat and is 0.2-0.4 m below the floodplain surface, and groundwater contours suggest flow is parallel to the stream direction. The water table responds immediately to precipitation events, and rises to the floodplain surface in significant rainfall events. Immediately downstream of the knickpoint, channel width increases by about a meter, and stream depth increases to ~1.5 meters. The water table immediately below the knickpoint possesses a steep gradient, and is up to one meter below the floodplain
Simulation of the Groundwater-Flow System in Pierce, Polk, and St. Croix Counties, Wisconsin
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
High resolution solutions of the Euler equations for vortex flows
International Nuclear Information System (INIS)
Murman, E.M.; Powell, K.G.; Rizzi, A.; Tel Aviv Univ., Israel)
1985-01-01
Solutions of the Euler equations are presented for M = 1.5 flow past a 70-degree-swept delta wing. At an angle of attack of 10 degrees, strong leading-edge vortices are produced. Two computational approaches are taken, based upon fully three-dimensional and conical flow theory. Both methods utilize a finite-volume discretization solved by a pseudounsteady multistage scheme. Results from the two approaches are in good agreement. Computations have been done on a 16-million-word CYBER 205 using 196 x 56 x 96 and 128 x 128 cells for the two methods. A sizable data base is generated, and some of the practical aspects of manipulating it are mentioned. The results reveal many interesting physical features of the compressible vortical flow field and also suggest new areas needing research. 16 references
Chemical-potential flow equations for graphene with Coulomb interactions
Fräßdorf, Christian; Mosig, Johannes E. M.
2018-06-01
We calculate the chemical potential dependence of the renormalized Fermi velocity and static dielectric function for Dirac quasiparticles in graphene nonperturbatively at finite temperature. By reinterpreting the chemical potential as a flow parameter in the spirit of the functional renormalization group (fRG) we obtain a set of flow equations, which describe the change of these functions upon varying the chemical potential. In contrast to the fRG the initial condition of the flow is nontrivial and has to be calculated separately. Our results are consistent with a charge carrier-independent Fermi velocity v (k ) for small densities n ≲k2/π , supporting the comparison of the zero-density fRG calculation of Bauer et al. [Phys. Rev. B 92, 121409 (2015), 10.1103/PhysRevB.92.121409], with the experiment of Elias et al. [Nat. Phys. 7, 701 (2011), 10.1038/nphys2049].
Numerical groundwater flow calculations at the Finnsjoen site
International Nuclear Information System (INIS)
Lindbom, B.; Boghammar, A.; Lindberg, H.; Bjelkaas, J.
1991-02-01
The Swedish Nuclear Fuel and Waste Management Company (SKB) has initiated a research project called SKB 91, which is related to performance assessment of repositories for high level waste from nuclear power plants. Specifically the Finnsjoen site is of concern. As part of this research project, the report describes groundwater flow calculations at the Finnsjoen site, located in northern Uppland, approximately 150 km north of Stockholm. The calculations have been performed with the finite element method applying the porous media approach. The project comprises three steps, the first of which is concerned with the presence of salt below a hydraulically significant structure. This step was modelled in two dimensions in a semi-generic fashion, while the two following steps comprised three-dimensional modelling of the site at a semi-regional and a local scale. The semi-regional model covered approximately 43 square km while the area of the local model was roughly 6.6 square km. The semi-regional model included well expressed regional fracture zones that were explicitly modelled in deterministic manner. The modelling was performed with the finite element code NAMMU, used together with the program-package HYPAC. The latter was used for pre- and postprocessing purposes. The modelling was performed with 8-noded brick elements for the three-dimensional calculations, and the two-dimensional model involved the use of 8-noded rectangular elements. The present report is a revised version of a report previously published as a working report. The difference between the present report and the previous one, is that the present report describes the conclusions more site-specifically, the presentation of a number of the cases tackled has been pruned down, some editorial effort has been put into having the volume of the report reduced, and finally the summary has been edited and cut down. (authors)
Groundwater flow modelling of Yamuna–Krishni interstream, a part ...
Indian Academy of Sciences (India)
interstream, a part of central Ganga Plain ... Water Board (CGWB) and Groundwater Depart- ment of ..... ment, have a discharge rate of 1500 L/min. ... mainly depends on electric power supply, tube- ..... Water Resources, Canberra, Australia.
Effects of groundwater-flow paths on nitrate concentrations across two riparian forest corridors
Speiran, Gary K.
2010-01-01
Groundwater levels, apparent age, and chemistry from field sites and groundwater-flow modeling of hypothetical aquifers collectively indicate that groundwater-flow paths contribute to differences in nitrate concentrations across riparian corridors. At sites in Virginia (one coastal and one Piedmont), lowland forested wetlands separate upland fields from nearby surface waters (an estuary and a stream). At the coastal site, nitrate concentrations near the water table decreased from more than 10 mg/L beneath fields to 2 mg/L beneath a riparian forest buffer because recharge through the buffer forced water with concentrations greater than 5 mg/L to flow deeper beneath the buffer. Diurnal changes in groundwater levels up to 0.25 meters at the coastal site reflect flow from the water table into unsaturated soil where roots remove water and nitrate dissolved in it. Decreases in aquifer thickness caused by declines in the water table and decreases in horizontal hydraulic gradients from the uplands to the wetlands indicate that more than 95% of the groundwater discharged to the wetlands. Such discharge through organic soil can reduce nitrate concentrations by denitrification. Model simulations are consistent with field results, showing downward flow approaching toe slopes and surface waters to which groundwater discharges. These effects show the importance of buffer placement over use of fixed-width, streamside buffers to control nitrate concentrations.
Groundwater recharge and flow on Montserrat, West Indies: Insights from groundwater dating
Hemmings, Brioch; Gooddy, Daren; Whitaker, Fiona; George Darling, W.; Jasim, Alia; Gottsmann, Joachim
2015-01-01
Study region Montserrat, Lesser Antilles, Caribbean. Study focus Analysis of δ2H and δ18O isotopes, and chlorofluorocarbon (CFC) anthropogenic tracers in Montserrat groundwater provides insights into the age and provenance of the spring waters. New hydrological insights δ2H and δ18O analysis indicates uniform recharge elevations for groundwaters on Montserrat. CFC-11 and CFC-12 analysis reveals age differences between isotopically similar, high elevation springs and low eleva...
Sahoo, Sasmita; Jha, Madan K.
2017-12-01
Process-based groundwater models are useful to understand complex aquifer systems and make predictions about their response to hydrological changes. A conceptual model for evaluating responses to environmental changes is presented, considering the hydrogeologic framework, flow processes, aquifer hydraulic properties, boundary conditions, and sources and sinks of the groundwater system. Based on this conceptual model, a quasi-three-dimensional transient groundwater flow model was designed using MODFLOW to simulate the groundwater system of Mahanadi River delta, eastern India. The model was constructed in the context of an upper unconfined aquifer and lower confined aquifer, separated by an aquitard. Hydraulic heads of 13 shallow wells and 11 deep wells were used to calibrate transient groundwater conditions during 1997-2006, followed by validation (2007-2011). The aquifer and aquitard hydraulic properties were obtained by pumping tests and were calibrated along with the rainfall recharge. The statistical and graphical performance indicators suggested a reasonably good simulation of groundwater flow over the study area. Sensitivity analysis revealed that groundwater level is most sensitive to the hydraulic conductivities of both the aquifers, followed by vertical hydraulic conductivity of the confining layer. The calibrated model was then employed to explore groundwater-flow dynamics in response to changes in pumping and recharge conditions. The simulation results indicate that pumping has a substantial effect on the confined aquifer flow regime as compared to the unconfined aquifer. The results and insights from this study have important implications for other regional groundwater modeling studies, especially in multi-layered aquifer systems.
Hydrochemistry of the groundwater flow systems in the Harwell region
International Nuclear Information System (INIS)
Alexander, J.
1984-12-01
A comprehensive range of geochemical and isotopic parameters were analysed in the groundwater samples taken from the high permeability formations in the Harwell region. These analyses were undertaken as part of a hydro-chemical validation of groundwater circulation patterns derived from potentiometric data. Hydro-chemical investigations were concentrated upon the Corallian and Great Oolite formations since these respectively overlie and underlie the Oxford Clay. (author)
Site-scale groundwater flow modelling of Ceberg
Energy Technology Data Exchange (ETDEWEB)
Walker, D. [Duke Engineering and Services (United States); Gylling, B. [Kemakta Konsult AB, Stockholm (Sweden)
1999-06-01
The Swedish Nuclear Fuel and Waste Management Company (SKB) SR 97 study is a comprehensive performance assessment illustrating the results for three hypothetical repositories in Sweden. In support of SR 97, this study examines the hydrogeologic modelling of the hypothetical site called Ceberg, which adopts input parameters from the SKB study site near Gideaa, in northern Sweden. This study uses a nested modelling approach, with a deterministic regional model providing boundary conditions to a site-scale stochastic continuum model. The model is run in Monte Carlo fashion to propagate the variability of the hydraulic conductivity to the advective travel paths from representative canister locations. A series of variant cases addresses uncertainties in the inference of parameters and the model of conductive fracturezones. The study uses HYDRASTAR, the SKB stochastic continuum (SC) groundwater modelling program, to compute the heads, Darcy velocities at each representative canister position, and the advective travel times and paths through the geosphere. The volumetric flow balance between the regional and site-scale models suggests that the nested modelling and associated upscaling of hydraulic conductivities preserve mass balance only in a general sense. In contrast, a comparison of the base and deterministic (Variant 4) cases indicates that the upscaling is self-consistent with respect to median travel time and median canister flux. These suggest that the upscaling of hydraulic conductivity is approximately self-consistent but the nested modelling could be improved. The Base Case yields the following results for a flow porosity of {epsilon}{sub f} 10{sup -4} and a flow-wetted surface area of a{sub r} = 0.1 m{sup 2}/(m{sup 3} rock): The median travel time is 1720 years. The median canister flux is 3.27x10{sup -5} m/year. The median F-ratio is 1.72x10{sup 6} years/m. The base case and the deterministic variant suggest that the variability of the travel times within
Site-scale groundwater flow modelling of Ceberg
International Nuclear Information System (INIS)
Walker, D.; Gylling, B.
1999-06-01
The Swedish Nuclear Fuel and Waste Management Company (SKB) SR 97 study is a comprehensive performance assessment illustrating the results for three hypothetical repositories in Sweden. In support of SR 97, this study examines the hydrogeologic modelling of the hypothetical site called Ceberg, which adopts input parameters from the SKB study site near Gideaa, in northern Sweden. This study uses a nested modelling approach, with a deterministic regional model providing boundary conditions to a site-scale stochastic continuum model. The model is run in Monte Carlo fashion to propagate the variability of the hydraulic conductivity to the advective travel paths from representative canister locations. A series of variant cases addresses uncertainties in the inference of parameters and the model of conductive fracture zones. The study uses HYDRASTAR, the SKB stochastic continuum (SC) groundwater modelling program, to compute the heads, Darcy velocities at each representative canister position, and the advective travel times and paths through the geosphere. The volumetric flow balance between the regional and site-scale models suggests that the nested modelling and associated upscaling of hydraulic conductivities preserve mass balance only in a general sense. In contrast, a comparison of the base and deterministic (Variant 4) cases indicates that the upscaling is self-consistent with respect to median travel time and median canister flux. These suggest that the upscaling of hydraulic conductivity is approximately self-consistent but the nested modelling could be improved. The Base Case yields the following results for a flow porosity of ε f 10 -4 and a flow-wetted surface area of a r = 0.1 m 2 /(m 3 rock): The median travel time is 1720 years. The median canister flux is 3.27x10 -5 m/year. The median F-ratio is 1.72x10 6 years/m. The base case and the deterministic variant suggest that the variability of the travel times within individual realisations is due to the
Zhang, Zhuo; Guo, Huaming; Zhao, Weiguang; Liu, Shuai; Cao, Yongsheng; Jia, Yongfeng
2018-04-01
Data on spatiotemporal variations in groundwater levels are crucial for understanding arsenic (As) behavior and dynamics in groundwater systems. Little is known about the influences of groundwater extraction on the transport and mobilization of As in the Hetao Basin, Inner Mongolia (China), so groundwater levels were recorded in five monitoring wells from 2011 to 2016 and in 57 irrigation wells and two multilevel wells in 2016. Results showed that groundwater level in the groundwater irrigation area had two troughs each year, induced by extensive groundwater extraction, while groundwater levels in the river-diverted (Yellow River) water irrigation area had two peaks each year, resulting from surface-water irrigation. From 2011 to 2016, groundwater levels in the groundwater irrigation area presented a decreasing trend due to the overextraction. Groundwater samples were taken for geochemical analysis each year in July from 2011 to 2016. Increasing trends were observed in groundwater total dissolved solids (TDS) and As. Owing to the reverse groundwater flow direction, the Shahai Lake acts as a new groundwater recharge source. Lake water had flushed the near-surface sediments, which contain abundant soluble components, and increased groundwater salinity. In addition, groundwater extraction induced strong downward hydraulic gradients, which led to leakage recharge from shallow high-TDS groundwater to the deep semiconfined aquifer. The most plausible explanation for similar variations among As, Fe(II) and total organic carbon (TOC) concentrations is the expected dissimilatory reduction of Fe(III) oxyhydroxides.
Energy Technology Data Exchange (ETDEWEB)
Kim, Chun Soo; Kim, Kyung Su; Bae, Dae Seok; Park, Byoung Yoon; Koh, Young Kown [Korea Atomic Energy Research Institute, Taejeon (Korea)
2000-03-01
The basic framework of groundwater flow is defined as a conceptual 3-D unit of groundwater system based on hydrogeological environments. The fundamental parameters consisting of groundwater system should include topography, geology and climatic conditions. Climatic conditions control the distribution and amounts of groundwater in an interesting study area. The driving forces responsible for groundwater movement are mainly determined by topographic characteristics. The configuration of groundwater system is also controlled by topography. The geological setting and structures control the reservoir size and groundwater flow path. The hydrogeological setting in Korea was classified by primarily topographic characteristics and considered by geological structures and tectonic division. The regional groundwater regime can be grouped into 3 regimes by tectonic setting and four groundwater regions based on an altitude. 35 refs., 9 figs., 21 tabs. (Author)
Hydrochemistry in the development of groundwater flow models at the Hanford site
International Nuclear Information System (INIS)
Early, T.O.
1986-01-01
Site characterization activities in progress at the Hanford Site include efforts to understand the groundwater flow regime within the Columbia River Basalt Group. Hydrochemical data from deep boreholes at Hanford suggest that groundwater has migrated upward at an unknown rate from the underlying sediments and mixed with more dilute shallow groundwaters within basalt aquifers. The driving force for upward flow is hypothesized to result from a regional flow system. Detailed analysis of deep groundwaters indicates that two major types exist. For example, water underlying the western part of the Site are sulfate poor and associated with relatively abundant dissolved methane. Deep groundwaters of the second type, lying to the east, are relatively sulfate rich but contain essentially no methane. Specific features of the source regions that yield these different geochemical types are poorly known but association of the western waters with methane-producing coal strata is proposed. At the level of the proposed repository evidence seems to point to little lateral flow. At shallower depths a somewhat more active lateral flow system is possible. The direction of lateral flow, whatever its rate, appears to be structurally controlled
International Nuclear Information System (INIS)
Kincaid, C.T.; Vail, L.W.; Devary, J.L.
1983-07-01
Research was conducted at Pacific Northwest Laboratory to develop a research computational package for the stochastic analysis of ground-water flow. Both unsteady and steady-state analysis were examined, and a steady-state research code was developed for the study of stochastic processes. This report describes the theoretical development of both unsteady and steady analyses, and presents the preliminary studies undertaken to verify and exercise the encoded algorithm. The stochastic analysis of ground-water flow is a promising new method which can supply more comprehensive analyses of the ground-water environment. The work reported herein provided experience in the methodology while producing a research-oriented stochastic analysis capability. Single-layer aquifers of horizontal extent were selected for this effort. Kriging has been employed to describe the uncertainty in field data. The resulting stochastic parameters enter the problem physics through boundary conditions and Darcy's equation. The mean and variance of the piezometric head are estimated by the stochastic analysis
International Nuclear Information System (INIS)
Atwood, H.; Picking, L.
1986-01-01
Ground-water flow through the Palo Duro and Tucumcari Basins is simulated by developing a hydrogeolgic profile and applying a cross-sectional, finite-element, numerical model to the profile. The profile is 350 miles long and 2 miles deep and extends from east-central New Mexico to the Texas-Oklahoma border. It is comprised of hydrogeologic units that are identified from geophysical well logs, sample logs, and core descriptions. A hydrogeologic unit as used in this profile is a physically continuous rock sequence with hydrologic properties that are relatively consistent throughout and distinct from surrounding units. The resulting hydrogeologic profile, with the exception of the Ogallala Formation and the Dockum Group, is discretized into a 6000-element mesh and a 22,000-element mesh. Permeability values assigned to hydrogeologic units were, in part, calculated from drill stem tests conducted throughout the Palo Duro Basin. Ground-water age and travel paths are determined by applying Darcy's equation to selected flow lines. The 170 million-year age determined from ground-water at points within the Wolfcamp Series compares favorably with the geochemical data for this region. An age of 188 million years is determined for the Pennsylvanian granite wash
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.
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
Mathur, Praveen; Sharma, Sarita; Soni, Bhupendra
2010-01-01
In the present work, an attempt is made to formulate multiple regression equations using all possible regressions method for groundwater quality assessment of Ajmer-Pushkar railway line region in pre- and post-monsoon seasons. Correlation studies revealed the existence of linear relationships (r 0.7) for electrical conductivity (EC), total hardness (TH) and total dissolved solids (TDS) with other water quality parameters. The highest correlation was found between EC and TDS (r = 0.973). EC showed highly significant positive correlation with Na, K, Cl, TDS and total solids (TS). TH showed highest correlation with Ca and Mg. TDS showed significant correlation with Na, K, SO4, PO4 and Cl. The study indicated that most of the contamination present was water soluble or ionic in nature. Mg was present as MgCl2; K mainly as KCl and K2SO4, and Na was present as the salts of Cl, SO4 and PO4. On the other hand, F and NO3 showed no significant correlations. The r2 values and F values (at 95% confidence limit, alpha = 0.05) for the modelled equations indicated high degree of linearity among independent and dependent variables. Also the error % between calculated and experimental values was contained within +/- 15% limit.
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
Akinwumiju, Akinola S.; Olorunfemi, Martins O.
2018-05-01
This study attempted to model the groundwater flow system of a drainage basin within the Basement Complex environment of Southwestern Nigeria. Four groundwater models were derived from Vertical Electrical Sounding (VES) Data, remotely sensed data, geological information (hydrolineaments and lithology) and borehole data. Subsequently, two sub-surface (local and regional) flow systems were delineated in the study area. While the local flow system is controlled by surface topography, the regional flow system is controlled by the networks of intermediate and deep seated faults/fractures. The local flow system is characterized by convergence, divergence, inflow and outflow in places, while the regional flow system is dominated by NNE-SSW and W-E flow directions. Minor flow directions include NNW-SSE and E-W with possible linkages to the main flow-paths. The NNE-SSW regional flow system is a double open ended flow system with possible linkage to the Niger Trough. The W-E regional flow system is a single open ended system that originates within the study area (with possible linkage to the NNE-SSW regional flow system) and extends to Ikogosi in the adjoining drainage basin. Thus, the groundwater drainage basin of the study area is much larger and extensive than its surface drainage basin. The all year round flowing (perennial) rivers are linked to groundwater outcrops from faults/fractures and contact zones. Consequently, larger percentage of annual rainwater usually leaves the basin in form of runoff and base flow. Therefore, the basin is categorized as a donor basin but with suspected subsurface water input at its northeastern axis.
Spatial distribution of groundwater recharge and base flow: Assessment of controlling factors
Directory of Open Access Journals (Sweden)
Z. Zomlot
2015-09-01
New hydrological insights for the region: The average resulting recharge is 235 mm/year and occurs mainly in winter. The overall moderate correlation between base flow estimates and modeled recharge rates indicates that base flow is a reasonable proxy of recharge. Groundwater recharge variation was explained in order of importance by precipitation, soil texture and vegetation cover; while base flow variation was strongly controlled by vegetation cover and groundwater depth. The results of this study highlight the important role of spatial variables in estimation of recharge and base flow. In addition, the prominent role of vegetation makes clear the potential importance of land-use changes on recharge and hence the need to include a proper strategy for land-use change in sustainable management of groundwater resources.
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
International Nuclear Information System (INIS)
Flach, G.P.
1999-01-01
A regional groundwater flow model encompassing approximately 100 mi 2 surrounding the C, K. L. and P reactor areas has been developed. The Reactor flow model is designed to meet the planning objectives outlined in the General Groundwater Strategy for Reactor Area Projects by providing a common framework for analyzing groundwater flow, contaminant migration and remedial alternatives within the Reactor Projects team of the Environmental Restoration Department
Energy Technology Data Exchange (ETDEWEB)
Flach, G.P.
1999-02-24
A regional groundwater flow model encompassing approximately 100 mi{sup 2} surrounding the C, K. L. and P reactor areas has been developed. The Reactor flow model is designed to meet the planning objectives outlined in the General Groundwater Strategy for Reactor Area Projects by providing a common framework for analyzing groundwater flow, contaminant migration and remedial alternatives within the Reactor Projects team of the Environmental Restoration Department.
Determination of Groundwater Flows Pattern in Surakarta Region Using the Activity Ratio of Tritium
International Nuclear Information System (INIS)
Wisjachudin Faisal; Agus Sulistyono; Brotopuspito, Kirbani Sri; Budi Legowo
2002-01-01
Tritium activity analysis on groundwater samples has been carried out at 13 different locations in Surakarta regency in order to determine the groundwater flow pattern. Tritium activity in the groundwater is measured by LSC (Liquid Scintillation Counter) Tri-Carb 2700TR Measurement of the optimum activity is done on sample volume ratio with cocktail 7.4 : 12.6 in operation 0.5 - 4.5 keV. The highest result fulfilled in the location of Lor In Hotel for 1566 dpm and the lowest is in the location of Kadipiro for 0.03 dpm. Those data have shown that groundwater flow come from western area to eastern area of Surakarta city. (author)
International Nuclear Information System (INIS)
Kurikami, Hiroshi; Kobayashi, Akira; Ohnishi, Yuzo; Chijimatsu, Masakazu
2003-01-01
In order to estimate the effects of coupled thermal-hydraulic-mechanical phenomena in near-field for geological disposal of high-level radioactive waste on a vast groundwater flow system, a far-field analysis was simulated based on the results of the simulation of coupled phenomena in near-field using averaged tensor and heat flux. From the results of the coupled analyses of near-field and far-field it was clarified that groundwater flow system was influenced by coupled phenomena in near-field. Moreover, it can be said that groundwater flux into a disposal tunnel is regarded as a complement to safety assessment of a disposal because it strongly correlates with traveling time of groundwater. (author)
Shallow groundwater in the Matanuska-Susitna Valley, Alaska—Conceptualization and simulation of flow
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
Revised model of regional groundwater flow in the Whiteshell research area
International Nuclear Information System (INIS)
Ophori, D.U.; Brown, A.; Chan, T.; Davison, C.C.; Gascoyne, M.; Scheier, N.W.; Stanchell, F.W.; Stevenson, D.R.
1996-08-01
Steady-state regional groundwater flow of the Whiteshell Research Area (WRA) has been simulated in order to evaluate alternate locations for a hypothetical nuclear fuel waste disposal vault that maximize the retention of vault contaminants in long, slow groundwater flow paths through the geosphere. A revised conceptual model of the hydrogeologic conditions was constructed using all the information obtained from field investigations at the WRA between 1977 and 1994. All the simulations were performed using AECL's three-dimensional finite element code, MOTIF. A base-case simulation was performed using average value estimates of hydraulic parameters obtained from the field data, and freshwater was assumed to occur in the entire groundwater flow region. The simulated freshwater heads did not compare favourably with the freshwater beads that were derived from the field data. The simulated equivalent freshwater heads for the final calibrated model compared reasonably well with measured heads in the network of boreholes at the WRA. The simulated recharge rate for the final model was 4.8 mm/a Most of the groundwater flow in the model occurred in local systems between ground surface and a depth of 1000 m. A particle tracking code, TRACK3D, was used to determine the pathways, travel times and exit locations of particles released from different depths in the groundwater velocity field of the calibrated model. The exit locations of these pathways were found to be controlled by the network of regional fracture zones in the model. These results were used to select a location for a hypothetical nuclear fuel waste disposal vault in the regional groundwater flow model that maximizes the retention of vault contaminants in long, slow groundwater flow paths. A smaller region of about 75 km 2 was identified around this location for the development of a local geosphere model. (author). 32 refs., 4 tabs., 29 figs
An Investigation of Groundwater Flow on a Coastal Barrier using Multi Electrode Profiling
DEFF Research Database (Denmark)
Poulsen, Søren Erbs; Christensen, Steen; Rasmussen, Keld Rømer
2008-01-01
Preliminary geophysical and hydrogeological investigations indicate that multi-electrode profiling (MEP) can be used to monitor groundwater salinity on a coastal barrier where a shallow thin aquifer discharges to the North Sea. A monitoring system including five groups of piezometers and five MEP...... groundwater modeling we hope to be able to quantify how time varying recharge, tides, and storms hitting the barrier affect groundwater flow and discharge to the sea. At the conference we will present monitoring results from the winter and spring 2008....
Groundwater Flow and Transport Model in Cecina Plain (Tuscany, Italy) using GIS processing
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 ...
Graham, Wendy D.; Tankersley, Claude D.
1994-05-01
Stochastic methods are used to analyze two-dimensional steady groundwater flow subject to spatially variable recharge and transmissivity. Approximate partial differential equations are developed for the covariances and cross-covariances between the random head, transmissivity and recharge fields. Closed-form solutions of these equations are obtained using Fourier transform techniques. The resulting covariances and cross-covariances can be incorporated into a Bayesian conditioning procedure which provides optimal estimates of the recharge, transmissivity and head fields given available measurements of any or all of these random fields. Results show that head measurements contain valuable information for estimating the random recharge field. However, when recharge is treated as a spatially variable random field, the value of head measurements for estimating the transmissivity field can be reduced considerably. In a companion paper, the method is applied to a case study of the Upper Floridan Aquifer in NE Florida.
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
First status report on regional ground-water flow modeling for Vacherie Dome, Louisiana
International Nuclear Information System (INIS)
1986-07-01
Regional ground-water flow within the principal geohydrologic units in the vicinity of Vacherie Dome, Louisiana is evaluated by developing a conceptual model of the flow regime within these units and testing the model using a three-dimensional, finite-difference flow code (SWENT). Semiquantitative sensitivity analyses (a limited parametric study) are conducted to define the system responses to changes in the conceptual model, particularly in regard to the geohydrologic properties. All steps leading to the final results and conclusions are incorporated in this report. The available data utilized in this study are summarized. The conceptual model is defined in terms of the areal and vertical averaging of lithologic units, aquifer properties, and hydrologic boundary conditions. The simulated ground-water flow fields are described with potentiometric surfaces, areas of upward and downward flow across aquitards, tables summarizing the horizontal and vertical volumetric flows through the principal units, ground-water travel times and paths, and Darcy velocities within specified finite-difference blocks. The reported work is the first stage of an ongoing evaluation of Vacherie Dome as a potential repository for high-level radioactive wastes. The results and conclusions should thus be considered preliminary and subject to modification with the collection of additional data. However, the report does provide a useful basis for describing the sensitivity of the conceptualization of ground-water flow to parameterization and, to a lesser extent, the uncertainties in the present conceptualization. 34 refs., 57 figs., 19 tabs
Mohamed, Lamees
2015-07-09
An integrated [very low frequency (VLF) electromagnetic, magnetic, remote sensing, field, and geographic information system (GIS)] study was conducted over the basement complex in southern Sinai (Feiran watershed) for a better understanding of the structural controls on the groundwater flow. The increase in satellite-based radar backscattering values following a large precipitation event (34 mm on 17–18 January 2010) was used to identify water-bearing features, here interpreted as preferred pathways for surface water infiltration. Findings include: (1) spatial analysis in a GIS environment revealed that the distribution of the water-bearing features (conductive features) corresponds to that of fractures, faults, shear zones, dike swarms, and wadi networks; (2) using VLF (43 profiles), magnetic (7 profiles) techniques, and field observations, the majority (85 %) of the investigated conductive features were determined to be preferred pathways for groundwater flow; (3) northwest–southeast- to north–south-trending conductive features that intersect the groundwater flow (southeast to northwest) at low angles capture groundwater flow, whereas northeast–southwest to east–west features that intersect the flow at high angles impound groundwater upstream and could provide potential productive well locations; and (4) similar findings are observed in central Sinai: east–west-trending dextral shear zones (Themed and Sinai Hinge Belt) impede south to north groundwater flow as evidenced by the significant drop in hydraulic head (from 467 to 248 m above mean sea level) across shear zones and by reorientation of regional flow (south–north to southwest–northeast). The adopted integrated methodologies could be readily applied to similar highly fractured basement arid terrains elsewhere. © 2015 Springer Science+Business Media Dordrecht
International Nuclear Information System (INIS)
Yamakawa, Tadashi; Munakata, Masahiro; Kimura, Hideo; Hyodo, Hiroshi
2007-03-01
Radionuclide migration toward the human environment is to be assessed as the part of long-term safety assessments of geologic disposal of radioactive waste. Geologic processes, which include volcanic activity, hydrothermal activity, seismicity and deformation, bring about hydrogeologic changes in the regional groundwater flow system around a repository site. Groundwater flow systems in Japan have been studied in several sites such as Tono mine, Kamaishi mine and Horonobe area, but methodology of studies in these sites does not have fully developed. This study was conducted to develop methodologies of boundary delineation for regional groundwater flow systems. Geographic Information System, GIS, was applied using available topographic, hydrologic and geologic data for an area of interest. Miyakoji in the Abukuma Mountains was selected as the area, for the reason of its simple geologic setting formed by granitic rocks and topographically gentle hills of drainage basin. Data used in this study cover topographic sheets, digital elevation model, satellite imagery, geologic maps, topographic classification maps, soil distribution maps and landuse maps. Through the GIS techniques using these data, thematic maps on topographic features, surface conditions, land coverage, geology and geologic structure and weathered crust were developed, and these thematic maps were further applied to extract four factors affecting the regional groundwater flows: topographic condition, precipitation recharge, fracture characteristics and potential flows. The present study revealed that, taking the potential groundwater flows and characteristics of fractured zones in the area into consideration, the groundwater flow system in Miyakoji drainage basin should be bounded by the Otakine Mountain and the northern part of Tokoha Drainage Basin. The delineated area is larger than understood before. (author)
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
Energy Technology Data Exchange (ETDEWEB)
Hosono, Takahiro, E-mail: hosono@chikyu.ac.jp [Research Institute for Humanity and Nature, 457-4 Motoyama Kamigamo, Kita-ku, Kyoto 603-8047 (Japan); Ikawa, Reo, E-mail: r_ikawa@es.sci.kumamoto-u.ac.jp [Graduate School of Science and Technology, Kumamoto University, 2-39-1 Kurokami, Kumamoto 860-8555 (Japan); Shimada, Jun, E-mail: jshimada@sci.kumamoto-u.ac.jp [Graduate School of Science and Technology, Kumamoto University, 2-39-1 Kurokami, Kumamoto 860-8555 (Japan); Nakano, Takanori, E-mail: nakanot@chikyu.ac.jp [Research Institute for Humanity and Nature, 457-4 Motoyama Kamigamo, Kita-ku, Kyoto 603-8047 (Japan); Saito, Mitsuyo, E-mail: misaito@hiroshima-u.ac.jp [Graduate School of Biosphere Science, Hiroshima University, 1-7-1, Kagamiyama, Higashi-Hiroshima, Hiroshima, 739-8521 (Japan); Onodera, Shin-ichi, E-mail: sonodera@hiroshima-u.ac.jp [Graduate School of Integrated Arts and Sciences, Hiroshima University, 1-7-1, Kagamiyama, Higashi-Hiroshima, Hiroshima, 739-8521 (Japan); Lee, Kang-Kun, E-mail: kklee@snu.ac.kr [School of Earth and Environmental Science, Seoul National University, San 56-1, Shinrim-dong, Kwanak-gu, Seoul 151-747 (Korea, Republic of); Taniguchi, Makoto, E-mail: makoto@chikyu.ac.jp [Research Institute for Humanity and Nature, 457-4 Motoyama Kamigamo, Kita-ku, Kyoto 603-8047 (Japan)
2009-04-15
The influence of human activities on the flow system and contamination of groundwater were investigated in Seoul City, South Korea, one of the largest Asian cities, using a combination of isotopes ({delta}D, T, {delta}{sup 15}N, {delta}{sup 18}O, {delta}{sup 34}S, and {sup 87}Sr/{sup 86}Sr). Eighteen representative groundwater and river water samples, which were collected over a wide area of the city, were compared with previously reported data. The distribution of stable isotopes ({delta}D and {delta}{sup 18}O) with groundwater potential data shows that recharged groundwater from either the surrounding mountainous area as well as the Han River and other surface streams discharged towards the northern-central part of the city, where a subway tunnel pumping station is located. It is suggested from T values (3.3 to 5.8 T.U.) that groundwater was recharged in the last 30 to 40 years. The {delta}{sup 34}S and {delta}{sup 15}N of SO{sub 4}{sup 2-} and NO{sub 3}{sup -} data were efficiently used as indicators of contamination by human activities. These isotopes clarified that the contribution of anthropogenic contaminants i.e., industrial and household effluents, waste landfills, and fertilizers, are responsible for the enrichment by SO{sub 4}{sup 2-} (> 30 ppm as SO{sub 4}{sup 2-}) and NO{sub 3}{sup -} (> 20 ppm as NO{sub 3}{sup -}) of groundwater. The {sup 87}Sr/{sup 86}Sr values of groundwater vary (0.71326 to 0.75058) in accordance with the host rocks of different origins. Mineral elements such as Ca are also suggested to be derived naturally from rocks. The groundwater under Seoul City is greatly affected by transportation of pollutants along the groundwater flow controlled by subway tunnel pumping, contributing to the degradation of water quality in urbanized areas.
International Nuclear Information System (INIS)
Hosono, Takahiro; Ikawa, Reo; Shimada, Jun; Nakano, Takanori; Saito, Mitsuyo; Onodera, Shin-ichi; Lee, Kang-Kun; Taniguchi, Makoto
2009-01-01
The influence of human activities on the flow system and contamination of groundwater were investigated in Seoul City, South Korea, one of the largest Asian cities, using a combination of isotopes (δD, T, δ 15 N, δ 18 O, δ 34 S, and 87 Sr/ 86 Sr). Eighteen representative groundwater and river water samples, which were collected over a wide area of the city, were compared with previously reported data. The distribution of stable isotopes (δD and δ 18 O) with groundwater potential data shows that recharged groundwater from either the surrounding mountainous area as well as the Han River and other surface streams discharged towards the northern-central part of the city, where a subway tunnel pumping station is located. It is suggested from T values (3.3 to 5.8 T.U.) that groundwater was recharged in the last 30 to 40 years. The δ 34 S and δ 15 N of SO 4 2- and NO 3 - data were efficiently used as indicators of contamination by human activities. These isotopes clarified that the contribution of anthropogenic contaminants i.e., industrial and household effluents, waste landfills, and fertilizers, are responsible for the enrichment by SO 4 2- (> 30 ppm as SO 4 2- ) and NO 3 - (> 20 ppm as NO 3 - ) of groundwater. The 87 Sr/ 86 Sr values of groundwater vary (0.71326 to 0.75058) in accordance with the host rocks of different origins. Mineral elements such as Ca are also suggested to be derived naturally from rocks. The groundwater under Seoul City is greatly affected by transportation of pollutants along the groundwater flow controlled by subway tunnel pumping, contributing to the degradation of water quality in urbanized areas.
Evaluation of in situ sulfate reduction as redox buffer capacity in groundwater flow path
International Nuclear Information System (INIS)
Ioka, Seiichiro; Iwatsuki, Teruki; Amano, Yuki; Furue, Ryoji
2007-01-01
For safety assessment of geological isolation, it is important to evaluate in situ redox buffer capacity in high-permeability zone as groundwater flow path. The study evaluated in situ sulfate reduction as redox buffer capacity in the conglomerate bedding in Toki Lignite-bearing Formation, which occurs at the lowest part of sedimentary rocks overlying basement granite. The bedding plays an important role as the main groundwater flow path. The result showed that in situ redox buffer capacity in the conglomerate bedding has been identified on first nine months, whereas in the following period the redox buffer capacity has not been identified for about fifteen months. This will be caused by the bedding became inappropriate for microbial survival as the organic matter which is needfuel for microbial activity was consumed. Thus, there will be limited redox buffer capacity in groundwater flow path even in formation including organic matter-bearing layer. (author)
Site-scale groundwater flow modelling of Aberg
Energy Technology Data Exchange (ETDEWEB)
Walker, D. [Duke Engineering and Services (United States); Gylling, B. [Kemakta Konsult AB, Stockholm (Sweden)
1998-12-01
The Swedish Nuclear Fuel and Waste Management Company (SKB) SR 97 study is a comprehensive performance assessment illustrating the results for three hypothetical repositories in Sweden. In support of SR 97, this study examines the hydrogeologic modelling of the hypothetical site called Aberg, which adopts input parameters from the Aespoe Hard Rock Laboratory in southern Sweden. This study uses a nested modelling approach, with a deterministic regional model providing boundary conditions to a site-scale stochastic continuum model. The model is run in Monte Carlo fashion to propagate the variability of the hydraulic conductivity to the advective travel paths from representative canister locations. A series of variant cases addresses uncertainties in the inference of parameters and the boundary conditions. The study uses HYDRASTAR, the SKB stochastic continuum groundwater modelling program, to compute the heads, Darcy velocities at each representative canister position and the advective travel times and paths through the geosphere. The nested modelling approach and the scale dependency of hydraulic conductivity raise a number of questions regarding the regional to site-scale mass balance and the method`s self-consistency. The transfer of regional heads via constant head boundaries preserves the regional pattern recharge and discharge in the site-scale model, and the regional to site-scale mass balance is thought to be adequate. The upscaling method appears to be approximately self-consistent with respect to the median performance measures at various grid scales. A series of variant cases indicates that the study results are insensitive to alternative methods on transferring boundary conditions from the regional model to the site-scale model. The flow paths, travel times and simulated heads appear to be consistent with on-site observations and simple scoping calculations. The variabilities of the performance measures are quite high for the Base Case, but the
Site-scale groundwater flow modelling of Aberg
International Nuclear Information System (INIS)
Walker, D.; Gylling, B.
1998-12-01
The Swedish Nuclear Fuel and Waste Management Company (SKB) SR 97 study is a comprehensive performance assessment illustrating the results for three hypothetical repositories in Sweden. In support of SR 97, this study examines the hydrogeologic modelling of the hypothetical site called Aberg, which adopts input parameters from the Aespoe Hard Rock Laboratory in southern Sweden. This study uses a nested modelling approach, with a deterministic regional model providing boundary conditions to a site-scale stochastic continuum model. The model is run in Monte Carlo fashion to propagate the variability of the hydraulic conductivity to the advective travel paths from representative canister locations. A series of variant cases addresses uncertainties in the inference of parameters and the boundary conditions. The study uses HYDRASTAR, the SKB stochastic continuum groundwater modelling program, to compute the heads, Darcy velocities at each representative canister position and the advective travel times and paths through the geosphere. The nested modelling approach and the scale dependency of hydraulic conductivity raise a number of questions regarding the regional to site-scale mass balance and the method's self-consistency. The transfer of regional heads via constant head boundaries preserves the regional pattern recharge and discharge in the site-scale model, and the regional to site-scale mass balance is thought to be adequate. The upscaling method appears to be approximately self-consistent with respect to the median performance measures at various grid scales. A series of variant cases indicates that the study results are insensitive to alternative methods on transferring boundary conditions from the regional model to the site-scale model. The flow paths, travel times and simulated heads appear to be consistent with on-site observations and simple scoping calculations. The variabilities of the performance measures are quite high for the Base Case, but the
Nicholaides, K. D.; O'Connor, M.; Cardenas, M. B.; Neilson, B. T.; Kling, G. W.
2017-12-01
Arctic permafrost degradation is occurring as global temperatures increase. In addition, recent evidence shows the Arctic is shifting from a sink to a source of carbon to the atmosphere. However, the cause of this shift is unclear, as is the role of newly exposed organic soil carbon leaching into groundwater and transported to surface water. This soil carbon may be photo-oxidized to CO2 or microbially respired to CO2 and methane, adding greenhouse gases to the atmosphere. The fate of carbon in permafrost is largely governed by the length of time spent in transport and the surface or subsurface route it follows. However, groundwater flow regimes within shallow active layer aquifers overlying permafrost is poorly understood. We determined to what extent smaller scale topography influences groundwater flow and residence times in arctic tundra. The study focused on Imnavait Creek watershed, a 1st-order drainage on the Alaskan North Slope underlain by continuous permafrost. We used direct measurements of hydraulic conductivities and porosities over a range of depths as well as basin-scale topography to develop vertically-integrated groundwater flow models. By systematically decreasing the amount of topographic detail, we were able to compare the influence of more detailed topography on groundwater flow estimates. Scaling up this model will be a useful tool in understanding how larger basins in permafrost will respond to future climate change and their contributions to greenhouse gases in the atmosphere.
Groundwater flow in the Venice lagoon and remediation of the Porto Marghera industrial area (Italy)
Beretta, Giovanni Pietro; Terrenghi, Jacopo
2017-05-01
This study aims to determine the groundwater flow in a large area of the Venice (northeast Italy) lagoon that is under great anthropogenic pressure, which is influencing the regional flow in the surficial aquifer (about 30 m depth). The area presents several elements that condition the groundwater flow: extraction by means of drainage pumps and wells; tidal fluctuation; impermeable barriers that define part of the coastline, rivers and artificial channels; precipitation; recharge, etc. All the elements were studied separately, and then they were brought together in a numerical groundwater flow model to estimate the impact of each one. Identification of the impact of each element will help to optimise the characteristics of the Porto Marghera remediation systems. Longstanding industrial activity has had a strong impact on the soil and groundwater quality, and expensive and complex emergency remediation measures in problematic locations have been undertaken to ensure the continuity of industrial and maritime activities. The land reclamation and remediation works withdraw 56-74% of the water budget, while recharge from the river accounts for about 21-48% of the input. Only 21-42% of groundwater in the modelled area is derived from natural recharge sources, untouched by human activity. The drop of the piezometric level due to the realization of the upgradient impermeable barrier can be counteracted with the reduction of the pumping rate of the remediation systems.
An analytical study on groundwater flow in drainage basins with horizontal wells
Wang, Jun-Zhi; Jiang, Xiao-Wei; Wan, Li; Wang, Xu-Sheng; Li, Hailong
2014-06-01
Analytical studies on release/capture zones are often limited to a uniform background groundwater flow. In fact, for basin-scale problems, the undulating water table would lead to the development of hierarchically nested flow systems, which are more complex than a uniform flow. Under the premise that the water table is a replica of undulating topography and hardly influenced by wells, an analytical solution of hydraulic head is derived for a two-dimensional cross section of a drainage basin with horizontal injection/pumping wells. Based on the analytical solution, distributions of hydraulic head, stagnation points and flow systems (including release/capture zones) are explored. The superposition of injection/pumping wells onto the background flow field leads to the development of new internal stagnation points and new flow systems (including release/capture zones). Generally speaking, the existence of n injection/pumping wells would result in up to n new internal stagnation points and up to 2n new flow systems (including release/capture zones). The analytical study presented, which integrates traditional well hydraulics with the theory of regional groundwater flow, is useful in understanding basin-scale groundwater flow influenced by human activities.
Understanding large scale groundwater flow to aid in repository siting
International Nuclear Information System (INIS)
Davison, C.C.; Brown, A.; Gascoyne, M.; Stevenson, D.R.; Ophori, D.U.
1996-01-01
Atomic Energy of Canada Limited (AECL) with support from Ontario Hydro has developed a concept for the safe disposal of Canada's nuclear fuel waste in a deep (500 to 1000 m) mined repository in plutonic rocks of the Canadian Shield. The disposal concept involves the use of multiple engineered and natural barriers to ensure long-term safety. The geosphere, comprised of the enclosing rock mass and the groundwater which occurs in cracks and pores in the rock, is expected to serve as an important natural barrier to the release and migration of wastes from the engineered repository. Although knowledge of the physical and chemical characteristics of the groundwater in the rock at potential repository sites is needed to help design the engineered barriers of the repository it can also be used to aid in repository siting, to take greater advantage of natural conditions in the geosphere to enhance its role as a barrier in the overall disposal system
Numerical solution of compressible flow equations inside an ejector
International Nuclear Information System (INIS)
Omid khah, M. R.; Navid Famili, M. H.; Jalili Keshtiban, E.
2002-01-01
Ejector is important equipment in the chemical industry. It is mainly used for vaccuming and mixing of flows. In the present work a computer modeling of the flow inside an ejector is used to give a better understanding of the principle of the operation of an ejector. Since the fluid inside an ejector passes through subsonic, sonic and supersonic regimens, the pressure field is used as the controlling variable and the density is found through the constitutive equations. The control volume method with a co-location grid, attached to the boundary is used to discretize the domain. The overall solution is obtained by the SIMPLEC method and to dissociate the pressure and the velocity grid Rhie-Chow interpolation method is employed. A central difference approximation method is used to approximate the density on the elements borders and the upwind approximation is used to correct the density correction factors. Both upwind, quick and minimum gradient methods were used to approximate the momentum variables on the control volumes. The resultant matrices are solved with the tri-diagonal method. The accuracy of the model is checked by simulating a flow regiment in a converging-diverging nozzle, and comparing the results with the available experimental data. The results show that for an inviscid the first order approximation produce as an accurate results as the higher order approximations while it has a better stability. However, for the viscous fluid the second order approximation produces a better understanding of the physics of the problem. The solution also showes that the flow field inside an ejector is a complex one and the shock wave has a great influence on the pressure field especially close to the walls. The upper convective quick method did not converge well in the shock calculations while the slowest descent method had a very stable behavior in the analysis of the shock behavior
Reconstructing the groundwater flow in the Baltic Basin during the Last glaciation
Saks, T.; Sennikovs, J.; Timuhins, A.; Kalvāns, A.
2012-04-01
In last decades it has been discussed that most large ice sheets tend to reside on warm beds even in harsh clima tic conditions and subglacial melting occurs due to geothermal heat flow and deformation heat of the ice flow. However the subglacial groundwater recharge and flow conditions have been addressed in only few studies. The aim of this study is to establish the groundwater flow pattern in the Baltic Basin below the Scandinavian ice sheet during the Late Weichselian glaciation. The calculation results are compared to the known distribution of the groundwater body of the glacial origin found in Cambrian - Vendian (Cm-V) aquifer in the Northern Estonia which is believed to have originated as a result of subglacial meltwater infiltration during the reoccurring glaciations. Steady state regional groundwater flow model of the Baltic Basin was used to simulate the groundwater flow beneath the ice sheet with its geometry adjusted to reflect the subglacial topography. Ice thickness modelling data (Argus&Peltier, 2010) was used for the setup of the boundary conditions: the meltwater pressure at the ice bed was assumed equal to the overlying ice mass. The modelling results suggest two main recharge areas of the Cm-V aquifer system, and reversed groundwater flow that persisted for at least 14 thousand years. Model results show that the groundwater flow velocities in the Cm-V aquifer in the recharge area in N-Estonia beneath the ice sheet exceeded the present velocities by a factor of 10 on average. The calculated meltwater volume recharged into the Cm-V aquifer system during the Late Weichselian corresponds roughly to the estimated, however, considering the fact, that the study area has been glaciated at least 4 times this is an overestimation. The modeling results attest the hypothesis of light dO18 groundwater glacial origin in the Cm-V aquifer system, however the volumes, timing and processes involved in the meltwater intrusion are yet to be explored. This study was
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
Conservation Laws for Gyrokinetic Equations for Large Perturbations and Flows
Dimits, Andris
2017-10-01
Gyrokinetic theory has proved to be very useful for the understanding of magnetized plasmas, both to simplify analytical treatments and as a basis for efficient numerical simulations. Gyrokinetic theories were previously developed in two extended orderings that are applicable to large fluctuations and flows as may arise in the tokamak edge and scrapeoff layer. In the present work, we cast the resulting equations in a field-theoretical variational form, and derive, up to second order in the respective orderings, the associated global and local energy and (linear and toroidal) momentum conservation relations that result from Noether's theorem. The consequences of these for the various possible choices of numerical discretization used in gyrokinetic simulations are considered. Prepared for US DOE by LLNL under Contract DE-AC52-07NA27344 and supported by the U.S. DOE, OFES.
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)
International Nuclear Information System (INIS)
Onoe, Hironori; Saegusa, Hiromitsu
2005-07-01
Japan Nuclear Cycle Development Institute 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 environment 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 mainly 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 analysis on the 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 former part of the Step 3 in site scale of the MIU project. As a result of the study, the uncertainty of hydrogeological model of the local scale and boundary conditions for the site scale model is decreased as stepwise investigation, and boundary conditions for groundwater flow analysis on the site scale model for the former part of the Step 3 could be obtained. (author)
Five easy equations for patient flow through an emergency department.
Madsen, Thomas Lill; Kofoed-Enevoldsen, Allan
2011-10-01
Queue models are effective tools for framing management decisions and Danish hospitals could benefit from awareness of such models. Currently, as emergency departments (ED) are under reorganization, we deem it timely to empirically investigate the applicability of the standard "M/M/1" queue model in order to document its relevance. We compared actual versus theoretical distributions of hourly patient flow from 27,000 patient cases seen at Frederiksberg Hospital's ED. Formulating equations for arrivals and capacity, we wrote and tested a five equation simulation model. The Poisson distribution fitted arrivals with an hour-of-the-day specific parameter. Treatment times exceeding 15 minutes were well-described by an exponential distribution. The ED can be modelled as a black box with an hourly capacity that can be estimated either as admissions per hour when the ED operates full hilt Poisson distribution or from the linear dependency of waiting times on queue number. The results show that our ED capacity is surprisingly constant despite variations in staffing. These findings led to the formulation of a model giving a compact framework for assessing the behaviour of the ED under different assumptions about opening hours, capacity and workload. The M/M/1 almost perfectly fits our. Thus modeling and simulations have contributed to the management process. not relevant. not relevant.
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
Slope instability in complex 3D topography promoted by convergent 3D groundwater flow
Reid, M. E.; Brien, D. L.
2012-12-01
Slope instability in complex topography is generally controlled by the interaction between gravitationally induced stresses, 3D strengths, and 3D pore-fluid pressure fields produced by flowing groundwater. As an example of this complexity, coastal bluffs sculpted by landsliding commonly exhibit a progression of undulating headlands and re-entrants. In this landscape, stresses differ between headlands and re-entrants and 3D groundwater flow varies from vertical rainfall infiltration to lateral groundwater flow on lower permeability layers with subsequent discharge at the curved bluff faces. In plan view, groundwater flow converges in the re-entrant regions. To investigate relative slope instability induced by undulating topography, we couple the USGS 3D limit-equilibrium slope-stability model, SCOOPS, with the USGS 3D groundwater flow model, MODFLOW. By rapidly analyzing the stability of millions of potential failures, the SCOOPS model can determine relative slope stability throughout the 3D domain underlying a digital elevation model (DEM), and it can utilize both fully 3D distributions of pore-water pressure and material strength. The two models are linked by first computing a groundwater-flow field in MODFLOW, and then computing stability in SCOOPS using the pore-pressure field derived from groundwater flow. Using these two models, our analyses of 60m high coastal bluffs in Seattle, Washington showed augmented instability in topographic re-entrants given recharge from a rainy season. Here, increased recharge led to elevated perched water tables with enhanced effects in the re-entrants owing to convergence of groundwater flow. Stability in these areas was reduced about 80% compared to equivalent dry conditions. To further isolate these effects, we examined groundwater flow and stability in hypothetical landscapes composed of uniform and equally spaced, oscillating headlands and re-entrants with differing amplitudes. The landscapes had a constant slope for both
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
International Nuclear Information System (INIS)
Geller, J.T.
1998-02-01
Laboratory experiments to simulate two-phase (gas and water) flow in fractured rock evolving from groundwater degassing were conducted in transparent replicas of natural rock fractures. These experiments extend the work by Geller et al. (1995) and Jarsjo and Geller (1996) that tests the hypothesis that groundwater degassing caused observed flow reductions in the Stripa Simulated Drift Experiment (SDE). Understanding degassing effects over a range of gas contents is needed due to the uncertainty in the gas contents of the water at the SDE. The main objectives of this study were to: (1) measure the effect of groundwater degassing on liquid flow rates for lower gas contents than the values used in Geller for linear flow geometry in the same fracture replicas of Geller; (2) provide a data set to develop a predictive model of two-phase flow in fractures for conditions of groundwater degassing; and (3) improve the certainty of experimental gas contents (this effort included modifications to the experimental system used by Geller et al. and separate gas-water equilibration tests). The Stripa site is being considered for a high-level radioactive waste repository
Concepts of Groundwater Occurrence and Flow Near Oak Ridge National Laboratory, Tennessee
International Nuclear Information System (INIS)
Moore, G.K.
1988-01-01
Previous studies of the area near Oak Ridge National Laboratory (ORNL) assumed that nearly all groundwater from precipitation and infiltration moves vertically down to the water table and then follows a combination of intergranular and fracture flow paths to the streams. These studies also generally assumed nearly linear flow paths, amounts of groundwater flow that are determined by differences in water-level elevation, large permeability differences between regolith and bedrock, and important hydrologic differences between named geologic units. It has been commonly stated for 37 years, for example, that the Conasauga Group has fewer cavities and is less permeable than the Chickamauga Group. All of these assumptions and conclusions are faulty. The new concepts in this report may be controversial, but they explain the available data. Only the stormflow zone from land surface to a depth of 1-2 m has a permeability large enough to transport most groundwater to the streams. Calculations show that 90-95% of all groundwater flow is in the stormflow zone, 4-9% is in a few water-producing intervals below the water table, and about 1% occurs in other intervals. The available data also show that nearly all groundwater flows through enlarged openings such as macropores, fractures, and cavities, and that there are no significant differences between regolith and bedrock or between the Conasauga Group and the Chickamauga group. Flow paths apparently are much more complex than was previously assumed. Multiple paths connect any two points below the water table, and each flow path is more likely to be tortuous than linear. Hydraulic gradients are affected by this complexity and by changes in hydraulic potential on steep hillsides. Below the water table, a large difference in the head of two points generally does not indicate a large flow rate between these points. Groundwater storage in amounts above field capacity is apparently intergranular in only the stormflow and vadose zones
Groundwater flow system stability in shield settings a multi-disciplinary approach
International Nuclear Information System (INIS)
Jensen, M.R.; Goodwin, B.W.
2004-01-01
Within the Deep Geologic Repository Technology Program (DGRTP) several Geoscience activities are focused on advancing the understanding of groundwater flow system evolution and geochemical stability in a Shield setting as affected by long-term climate change. A key aspect is developing confidence in predictions of groundwater flow patterns and residence times as they relate to the safety of a Deep Geologic Repository for used nuclear fuel waste. A specific focus in this regard has been placed on constraining redox stability and groundwater flow system dynamics during the Pleistocene. Attempts are being made to achieve this through a coordinated multi-disciplinary approach intent on; i) demonstrating coincidence between independent geo-scientific data; ii) improving the traceability of geo-scientific data and its interpretation within a conceptual descriptive model(s); iii) improving upon methods to assess and demonstrate robustness in flow domain prediction(s) given inherent flow domain uncertainties (i.e. spatial chemical/physical property distributions; boundary conditions) in time and space; and iv) improving awareness amongst geo-scientists as to the utility various geo-scientific data in supporting a repository safety case. Coordinated by the DGRTP, elements of this program include the development of a climate driven Laurentide ice-sheet model to constrain the understanding of time rate of change in boundary conditions most affecting the groundwater flow domain and its evolution. Further work has involved supporting WRA Paleo-hydrogeologic studies in which constrained thermodynamic analyses coupled with field studies to characterize the paragenesis of fracture infill mineralogy are providing evidence to premise understandings of possible depth of penetration by oxygenated glacial recharge. In parallel. numerical simulations have been undertaken to illustrate aspect of groundwater flow system stability and evolution in a Shield setting. Such simulations
Stream flow - its estimation, uncertainty and interaction with groundwater and floodplains
DEFF Research Database (Denmark)
Poulsen, Jane Bang
, floodplain hydraulics and sedimentation patterns has been investigated along a restored channel section of Odense stream, Denmark. Collected samples of deposited sediment, organic matter and phosphorus on the floodplain were compared with results from a 2D dynamic flow model. Three stage dependent flow...... regimes were predicted by the flow model with shifting primary overbank flow and zones of flow confluence. These dynamic flow patterns were found to correlate with the spatial deposition of total phosphorus (11.4 g m-2), organic matter (0.65 kg m-2) and sediment (4.72 kg m-2), and zones of major total...... sediment deposition coincided with the flow confluence zones. The revealed complex spatially and temporally changing floodplain flow pattern was found to play a decisive role for the deposition processes. The interaction between stream flow and groundwater from catchment to point scale has been...
Berger, David L.; Mayers, C. Justin; Garcia, C. Amanda; Buto, Susan G.; Huntington, Jena M.
2016-07-29
The Diamond Valley flow system consists of six hydraulically connected hydrographic areas in central Nevada. The general down-gradient order of the areas are southern and northern Monitor Valleys, Antelope Valley, Kobeh Valley, Stevens Basin, and Diamond Valley. Groundwater flow in the Diamond Valley flow system terminates at a large playa in the northern part of Diamond Valley. Concerns relating to continued water-resources development of the flow system resulted in a phased hydrologic investigation that began in 2005 by the U.S. Geological Survey in cooperation with Eureka County. This report presents the culmination of the phased investigation to increase understanding of the groundwater resources of the basin-fill aquifers in the Diamond Valley flow system through evaluations of groundwater chemistry and budgets. Groundwater chemistry was characterized using major ions and stable isotopes from groundwater and precipitation samples. Groundwater budgets accounted for all inflows, outflows, and changes in storage, and were developed for pre-development (pre-1950) and recent (average annual 2011–12) conditions. Major budget components include groundwater discharge by evapotranspiration and groundwater withdrawals; groundwater recharge by precipitation, and interbasin flow; and storage change.
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)
A site scale analysis of groundwater flow and salinity distribution in the Aespoe area
International Nuclear Information System (INIS)
Svensson, Urban
1997-10-01
The objective of the study is to develop, calibrate and apply a numerical simulation model of the Aespoe area. An area of 1.8 x 1.8 km 2 , centred around the Aespoe Hard Rock Laboratory (HRL), gives the horizontal extent of the model. In the vertical direction the model follows the topography at the upper boundary and has a lower boundary at 1000 metres below sea level. The model is based on a mathematical model that includes equations for the Darcy velocities, mass conservation and salinity distribution. Gravitational effects are thus fully accounted for. A regional groundwater model was used to generate boundary conditions for vertical and bottom boundaries. Transmissivities of fracture zones and conductivities for the rock in between, as used in the model, are based on field data. An extensive calibration of the model is carried out, using data for natural conditions (i.e. prior to the construction of the Aespoe HRL), drawdowns from a pump test and data collected during the excavation of the tunnel. A satisfactory agreement with field data is obtained by the calibration. Main results from the model include vertical and horizontal sections of flow, salinity and hydraulic head distributions for natural conditions and for completed tunnel. A sensitivity study, where boundary conditions and material properties are modified, is also carried out. The model is also used to describe some characteristic features of the site like infiltration rates, flux statistics at a depth of 450 metres, salinity of inflows to the tunnel and flow and salinity distributions in fracture zones. The general conclusion of the study is that the model developed can simulate the conditions at Aespoe, both natural and with Aespoe HRL present, in a realistic manner
Groundwater flow systems in the great Aletsch glacier region (Valais, Switzerland)
Alpiger, Andrea; Loew, Simon
2014-05-01
Groundwater flow systems in Alpine areas are often complex and challenging to investigate due to special topographic and climatic conditions governing groundwater recharge and bedrock flow. Studies seeking to characterize high-alpine groundwater systems remain rare, but are of high interest, e.g. for water supply, hydropower systems, traffic tunnels or rock slope deformation and landslide hazards. The goal of this study is to better understand the current and past groundwater flow systems of the UNESCO World Heritage mountain ridge separating the great Aletsch glacier and the Rhone valley, considering climatic and glacier fluctuations during the Lateglacial and Holocene periods. This ridge is crossed by a hydropower bypass drift (Riederhornstollen) and is composed of fractured crystalline rocks overlain by various types of landslides and glacial deposits. Surface hydrology observations (fracture properties, groundwater seepage, spring lines and physico-chemical parameters) and hydropower drift inflow measurements contributed to the characterization of bedrock hydraulic conductivities and preferential groundwater pathways. Basic conceptual hydrogeological models were tested with observed drift inflows and the occurrence of springs using free-surface, variably saturated, vertical 2D groundwater flow models (using the code SEEP/W from GeoStudio 2007). Already simple two-layer models, representing profile sections orthogonal to the mountain ridge, provided useful results. Simulations show that differences in the occurrence of springs on each side of the mountain ridge are likely caused by the occurrence of glacial till (generating perched groundwater), the deep-seated sagging landslide mass, faults and asymmetric ridge topography, which together force the main groundwater flow direction to be oriented towards the Rhone valley, even from beyond the mountain ridge. Surprisingly, the most important springs (those with high discharge rates) are located at high elevations
Modelling of seasonal dynamics of Wetland-Groundwater flow interaction in the Canadian Prairies
Ali, Melkamu; Nussbaumer, Raphaël; Ireson, Andrew; Keim, Dawn
2015-04-01
Wetland-shallow groundwater interaction is studied at the St. Denis National Wildlife Area in Saskatchewan, Canada, located within the northern glaciated prairies of North America. Ponds in the Canadian Prairies are intermittently connected by fill-spill processes in the spring and growing season of some wetter years. The contribution of the ponds and wetlands to groundwater is still a significant research challenge. The objective of this study is to evaluate model's ability to reproduce observed effects of groundwater-wetland interactions including seasonal pattern of shallow groundwater table, intended flow direction and to quantify the depression induced infiltration from the wetland to the surrounding uplands. The integrated surface-wetland-shallow groundwater processes and the changes in land-energy and water balances caused by the flow interaction are simulated using ParFlow-CLM at a small watershed of 1km2 containing both permanent and seasonal wetland complexes. We compare simulated water table depth with piezometers reading monitored by level loggers at the watershed. We also present the strengths and limitations of the model in reproducing observed behaviour of the groundwater table response to the spring snowmelt and summer rainfall. Simulations indicate that the shallow water table at the uphill recovers quickly after major rainfall events in early summer that generates lateral flow to the pond. In late summer, the wetland supplies water to the surrounding upland when the evapotranspiration is higher than the precipitation in which more water from the root zone is up taken by plants. Results also show that Parflow-CLM is able to reasonably simulate the water table patterns response to summer rainfall, while it is insufficient to reproduce the spring snowmelt infiltration which is the most dominant hydrological process in the Prairies.
Reitman, Nadine G.; Ge, Shemin; Mueller, Karl
2014-09-01
Groundwater flow is an important control on subsurface evaporite (salt) dissolution. Salt dissolution can drive faulting and associated subsidence on the land surface and increase salinity in groundwater. This study aims to understand the groundwater flow system of Gypsum Canyon watershed in the Paradox Basin, Utah, USA, and whether or not groundwater-driven dissolution affects surface deformation. The work characterizes the groundwater flow and solute transport systems of the watershed using a three-dimensional (3D) finite element flow and transport model, SUTRA. Spring samples were analyzed for stable isotopes of water and total dissolved solids. Spring water and hydraulic conductivity data provide constraints for model parameters. Model results indicate that regional groundwater flow is to the northwest towards the Colorado River, and shallow flow systems are influenced by topography. The low permeability obtained from laboratory tests is inconsistent with field observed discharges, supporting the notion that fracture permeability plays a significant role in controlling groundwater flow. Model output implies that groundwater-driven dissolution is small on average, and cannot account for volume changes in the evaporite deposits that could cause surface deformation, but it is speculated that dissolution may be highly localized and/or weaken evaporite deposits, and could lead to surface deformation over time.
Region-scale groundwater flow modelling of generic high level waste disposal sites
International Nuclear Information System (INIS)
Metcalfe, D.
1996-02-01
Regional-scale groundwater flow modelling analyses are performed on generic high level waste (HLW) disposal sites to assess the extent to which a large crystalline rock mass such as a pluton or batholith can be expected to contain and isolate HLW in terms of hydraulic considerations, for a variety of geologic and hydrogeologic conditions. The two-dimensional cross-sectional conceptual models of generic HLW disposal sites are evaluated using SWIFT III, which is a finite-difference flow and transport code. All steps leading to the final results and conclusions are incorporated in this report. The available data and information on geological and hydrogeologic conditions in plutons and batholiths are summarized. The generic conceptual models developed from this information are defined in terms of the finite difference grid, the geologic and hydrogeologic properties and the hydrologic boundary conditions used. The modelled results are described with contour maps showing the modelled head fields, groundwater flow paths and travel times and groundwater flux rates within the modelled systems. The results of the modelling analyses are used to develop general conclusions on the scales and patterns of groundwater flow in granitic plutons and batholiths. The conclusions focus on geologic and hydrogeologic characteristics that can result in favourable conditions, in terms of hydraulic considerations, for a HLW repository. (author) 43 refs., 9 tabs., 40 figs
Mohamed, Lamees; Sultan, Mohamed; Ahmed, Mohamed; Zaki, Abotalib; Sauck, William; Soliman, Farouk; Yan, Eugene; Elkadiri, Racha; Abouelmagd, Abdou
2015-01-01
of the structural controls on the groundwater flow. The increase in satellite-based radar backscattering values following a large precipitation event (34 mm on 17–18 January 2010) was used to identify water-bearing features, here interpreted as preferred pathways
De Biase, C.; Carminati, A.; Oswald, S.E.; Thullner, M.
2013-01-01
Vertical flow systems filled with porous medium have been shown to efficiently remove volatile organic contaminants (VOCs) from contaminated groundwater. To apply this semi-natural remediation strategy it is however necessary to distinguish between removal due to biodegradation and due to volatile
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
3-D numerical modelling of groundwater flow for scenario-based ...
African Journals Online (AJOL)
The data related to piezometric water levels, canal gauges, well logs, meteorological and lithological information were collected from Punjab Irrigation Department (PID), Water and Power Development Authority (WAPDA). Groundwater flow models for both steady and transient conditions were set-up using FEFLOW-3D.
Van Der Grift, B.; Rozemeijer, J. C.; Griffioen, J.; Van Der Velde, Y.
2014-01-01
The retention of phosphorus in surface waters through co-precipitation of phosphate with Fe-oxyhydroxides during exfiltration of anaerobic Fe(II) rich groundwater is not well understood. We developed an experimental field set-up to study Fe(II) oxidation and P immobilization along the flow-path from
Grift, van der B.; Rozemeijer, J.C.; Griffioen, J.; Velde, van der Y.
2014-01-01
The retention of phosphorus in surface waters though co-precipitation of phosphate with Fe-oxyhydroxides during exfiltration of anaerobic Fe(II) rich groundwater is not well understood. We developed an experimental field set-up to study Fe(II) oxidation and 5 P immobilization along the flow-path
van der Grift, B.; Rozemeijer, J. C.; Griffioen, J.; van der Velde, Y.
2014-01-01
The retention of phosphorus in surface waters though co-precipitation of phosphate with Fe-oxyhydroxides during exfiltration of anaerobic Fe(II) rich groundwater is not well understood. We developed an experimental field set-up to study Fe(II) oxidation and P immobilization along the flow-path from
Stepwise hydrogeological modeling and groundwater flow analysis on site scale (step 2)
International Nuclear Information System (INIS)
Onoe, Hironori; Saegusa, Hiromitsu; Endo, Yoshinobu
2005-02-01
One of the main goals of the Mizunami Underground Research Laboratory Project is to establish comprehensive techniques for investigation, analysis, and assessment of the deep geological environment. To achieve this goal, a variety of investigations are being conducted using an iterative approach. In this study, hydrogeological modeling and groundwater flow analyses have been carried out using the data from surface-based investigations at Step 2, in order to synthesize the investigation results, to evaluate the uncertainty of the hydrogeological model, and to specify items for further investigation. The results of this study are summarized as follows: 1) The understanding of groundwater flow is enhanced, and the hydrogeological model has renewed; 2) The importance of faults as major groundwater flow pathways has been demonstrated; 3) The importance of iterative approach as progress of investigations has been demonstrated; 4) Geological and hydraulic characteristics of faults with orientation of NNW, NW and NE were shown to be especially significant; 5) the hydraulic properties of the Lower Sparsely Fractured Domain (LSFD) significantly influence the groundwater flow. The main items specified for further investigations are summarized as follows: 1) Geological and hydraulic characteristics of NNW, NW and NE trending faults; 2) Hydraulic properties of the LSFD; 3) More accuracy upper and lateral boundary conditions of the site scale model. (author)
Comparison of groundwater flow in Southern California coastal aquifers
Hanson, Randall T.; Izbicki, John A.; Reichard, Eric G.; Edwards, Brian D.; Land, Michael; Martin, Peter
2009-01-01
Development of the coastal aquifer systems of Southern California has resulted in overdraft, changes in streamflow, seawater intrusion, land subsidence, increased vertical flow between aquifers, and a redirection of regional flow toward pumping centers. These water-management challenges can be more effectively addressed by incorporating new understanding of the geologic, hydrologic, and geochemical setting of these aquifers.
Kozar, Mark D.; McCoy, Kurt J.; Britton, James Q.; Blake, B.M.
2017-01-01
The Pocahontas No. 3 coal seam in southern West Virginia has been extensively mined by underground methods since the 1880’s. An extensive network of abandoned mine entries in the Pocahontas No. 3 has since filled with good-quality water, which is pumped from wells or springs discharging from mine portals (adits), and used as a source of water for public supplies. This report presents results of a three-year investigation of the geology, hydrology, geochemistry, and groundwater flow processes within abandoned underground coal mines used as a source of water for public supply in the Elkhorn area, McDowell County, West Virginia. This study focused on large (> 500 gallon per minute) discharges from the abandoned mines used as public supplies near Elkhorn, West Virginia. Median recharge calculated from base-flow recession of streamflow at Johns Knob Branch and 12 other streamflow gaging stations in McDowell County was 9.1 inches per year. Using drainage area versus mean streamflow relationships from mined and unmined watersheds in McDowell County, the subsurface area along dip of the Pocahontas No. 3 coal-mine aquifer contributing flow to the Turkey Gap mine discharge was determined to be 7.62 square miles (mi2), almost 10 times larger than the 0.81 mi2 surface watershed. Results of this investigation indicate that groundwater flows down dip beneath surface drainage divides from areas up to six miles east in the adjacent Bluestone River watershed. A conceptual model was developed that consisted of a stacked sequence of perched aquifers, controlled by stress-relief and subsidence fractures, overlying a highly permeable abandoned underground coal-mine aquifer, capable of substantial interbasin transfer of water. Groundwater-flow directions are controlled by the dip of the Pocahontas No. 3 coal seam, the geometry of abandoned mine workings, and location of unmined barriers within that seam, rather than surface topography. Seven boreholes were drilled to intersect
Groundwater flow model for the Little Plover River basin in Wisconsin’s Central Sands
Ken Bradbury,; Fienen, Michael N.; Kniffin, Maribeth; Jacob Krause,; Westenbroek, Stephen M.; Leaf, Andrew T.; Barlow, Paul M.
2017-01-01
The Little Plover River is a groundwater-fed stream in the sand plains region of central Wisconsin. In this region, sandy sediment deposited during or soon after the last glaciation forms an important unconfined sand and gravel aquifer. This aquifer supplies water for numerous high-capacity irrigation, municipal, and industrial wells that support a thriving agricultural industry. In recent years the addition of many new wells, combined with observed diminished flows in the Little Plover and other nearby rivers, has raised concerns about the impacts of the wells on groundwater levels and on water levels and flows in nearby lakes, streams, and wetlands. Diverse stakeholder groups, including well operators, Growers, environmentalists, local land owners, and regulatory and government officials have sought a better understanding of the local groundwater-surface water system and have a shared desire to balance the water needs of the he liagricultural, industrial, and urban users with the maintenance and protection of groundwater-dependent natural resources. To help address these issues, the Wisconsin Department of Natural Resources requested that the Wisconsin Geological and Natural History Survey and U.S. Geological Survey cooperatively develop a groundwater flow model that could be used to demonstrate the relationships among groundwater, surface water, and well withdrawals and also be a tool for testing and evaluating alternative water management strategies for the central sands region. Because of an abundance of previous studies, data availability, local interest, and existing regulatory constraints the model focuses on the Little Plover River watershed, but the modeling methodology developed during this study can apply to much of the larger central sands of Wisconsin. The Little Plover River groundwater flow model simulates three-dimensional groundwater movement in and around the Little Plover River basin under steady-state and transient conditions. This model
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
Erban, Laura E.; Gorelick, Steven M.
2016-04-01
Rice production in Cambodia, essential to food security and exports, is largely limited to the wet season. The vast majority (96%) of land planted with rice during the wet season remains fallow during the dry season. This is in large part due to lack of irrigation capacity, increases in which would entail significant consequences for Cambodia and Vietnam, located downstream on the Mekong River. Here we quantify the extent of the dry season ;deficit; area in the Cambodian Mekong River catchment, using a recent agricultural survey and our analysis of MODIS satellite data. Irrigation of this land for rice production would require a volume of water up to 31% of dry season Mekong River flow to Vietnam. However, the two countries share an aquifer system in the Mekong Delta, where irrigation demand is increasingly met by groundwater. We estimate expansion rates of groundwater-irrigated land to be >10% per year in the Cambodian Delta using LANDSAT satellite data and simulate the effects of future expansion on groundwater levels over a 25-year period. If groundwater irrigation continues to expand at current rates, the water table will drop below the lift limit of suction pump wells, used for domestic supply by >1.5 million people, throughout much of the area within 15 years. Extensive groundwater irrigation jeopardizes access for shallow domestic water supply wells, raises the costs of pumping for all groundwater users, and may exacerbate arsenic contamination and land subsidence that are already widespread hazards in the region.
Kolbe, T.; Abbott, B. W.; Thomas, Z.; Labasque, T.; Aquilina, L.; Laverman, A.; Babey, T.; Marçais, J.; Fleckenstein, J. H.; Peiffer, S.; De Dreuzy, J. R.; Pinay, G.
2016-12-01
Groundwater contamination by nitrate is nearly ubiquitous in agricultural regions. Nitrate is highly mobile in groundwater and though it can be denitrified in the aquifer (reduced to inert N2 gas), this process requires the simultaneous occurrence of anoxia, an electron donor (e.g. organic carbon, pyrite), nitrate, and microorganisms capable of denitrification. In addition to this the ratio of the time groundwater spent in a denitrifying environment (exposure time) to the characteristic denitrification reaction time plays an important role, because denitrification can only occur if the exposure time is longer than the characteristic reaction time. Despite a long history of field studies and numerical models, it remains exceedingly difficult to measure or model exposure times in the subsurface at the catchment scale. To approach this problem, we developed a unified modelling approach combining measured environmental proxies with an exposure time based reactive transport model. We measured groundwater age, nitrogen and sulfur isotopes, and water chemistry from agricultural wells in an unconfined aquifer in Brittany, France, to quantify changes in nitrate concentration due to dilution and denitrification. Field data showed large differences in nitrate concentrations among wells, associated with differences in the exposure time distributions. By constraining a catchment-scale characteristic reaction time for denitrification with water chemistry proxies and exposure times, we were able to assess rates of denitrification along groundwater flow paths. This unified modeling approach is transferable to other catchments and could be further used to investigate how catchment structure and flow dynamics interact with biogeochemical processes such as denitrification.
Second status report on regional ground-water flow modeling for the Palo Duro Basin, Texas
International Nuclear Information System (INIS)
1986-07-01
Regional ground-water flow within the principal geohydrologic units of the Palo Duro Basin is evaluated by developing a conceptual model of the flow regime and testing the model using a three-dimensional, finite-difference flow code. Sensitivity analyses (a limited parametric study) are conducted to define the system responses to changes in the conceptual model. Of particular interest are the impacts of salt permeability and potential climatic changes on the system response. The conceptual model is described in terms of its areal and vertical discretization, aquifer properties, fluid properties and hydrologic boundary conditions. The simulated ground-water flow fields are described with potentiometric surfaces, tables summarizing the areal and vertical volumetric flows through the principal units, and Darcy velocities within specified finite-difference blocks. The reported work is the second stage of an ongoing evaluation of the Palo Duro Basin as a potential repository for high-level radioactive wastes. The results and conclusions should thus be considered preliminary and subject to modification with the collection of additional data. However, the report does provide a useful basis for describing the sensitivity of the present conceptualization of ground-water flow to particular parameters and, to a lesser extent, the uncertainties in the present conceptualization. 28 refs., 44 figs., 13 tabs
Dumouchelle, D.H.; Schalk, C.W.; Rowe, G.L.; De Roche, J.T.
1993-01-01
Ground water is the primary source of water in the Wright-Patterson Air Force Base area. The aquifer consists of glacial sands and gravels that fill a buried bedrock-valley system. Consolidated rocks in the area consist of poorly permeable Ordovician shale of the Richmondian stage, in the upland areas, the Brassfield Limestone of Silurian age. The valleys are filled with glacial sediments of Wisconsinan age consisting of clay-rich tills and coarse-grained outwash deposits. Estimates of hydraulic conductivity of the shales based on results of displacement/recovery tests range from 0.0016 to 12 feet per day; estimates for the glacial sediments range from less than 1 foot per day to more than 1,000 feet per day. Ground water flow from the uplands towards the valleys and the major rivers in the region, the Great Miami and the Mad Rivers. Hydraulic-head data indicate that ground water flows between the bedrock and unconsolidated deposits. Data from a gain/loss study of the Mad River System and hydrographs from nearby wells reveal that the reach of the river next to Wright-Patterson Air Force Base is a ground-water discharge area. A steady-state, three-dimensional ground-water-flow model was developed to simulate ground-water flow in the region. The model contains three layers and encompasses about 100 square miles centered on Wright-Patterson Air Force Base. Ground water enters the modeled area primarily by river leakage and underflow at the model boundary. Ground water exits the modeled area primarily by flow through the valleys at the model boundaries and through production wells. A model sensitivity analysis involving systematic changes in values of hydrologic parameters in the model indicates that the model is most sensitive to decreases in riverbed conductance and vertical conductance between the upper two layers. The analysis also indicates that the contribution of water to the buried-valley aquifer from the bedrock that forms the valley walls is about 2 to 4
Research on fracture analysis, groundwater flow and sorption processes in fractured rocks
Energy Technology Data Exchange (ETDEWEB)
Lee, Dae-Ha; Kim, Won-Young; Lee, Seung-Gu [Korea Institute of Geology Mining and Materials, Taejon (KR)] (and others)
1999-12-01
Due to increasing demand for numerous industrial facilities including nuclear power plants and waste repositories, the feasibility of rocks masses as sites for the facilities has been a geological issue of concern. Rock masses, in general, comprises systems of fractures which can provide pathways for groundwater flow and may also affect the stability of engineered structures. For the study of groundwater flow and sorption processes in fractured rocks, five boreholes were drilled. A stepwise and careful integration of various data obtained from field works and laboratory experiments were carried out to analyze groundwater flow in fractured rocks as follows; (1) investigation of geological feature of the site, (2) identification and characterization of fracture systems using core and televiewer logs, (3) determination of hydrogeological properties of fractured aquifers using geophysical borehole logging, pumping and slug tests, and continuous monitoring of groundwater level and quality, (4) evaluation of groundwater flow patterns using fluid flow modeling. The results obtained from these processes allow a qualitative interpretation of fractured aquifers in the study area. Column experiments of some reactive radionuclides were also performed to examine sorption processes of the radionuclides including retardation coefficients. In addition, analyses of fracture systems covered (1) reconstruction of the Cenozoic tectonic movements and estimation of frequency indices for the Holocene tectonic movements, (2) determination of distributions and block movements of the Quaternary marine terraces, (3) investigation of lithologic and geotechnical nature of study area, and (4) examination of the Cenozoic volcanic activities and determination of age of the dike swarms. Using data obtained from above mentioned analyses along with data related to earthquakes and active faults, probabilistic approach was performed to determine various potential hazards which may result from the
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
International Nuclear Information System (INIS)
Lee, R.; Ketelle, D.
1987-01-01
The Copper Ridge Dolomite of the Upper Cambrian Knox Group underlies a site at Oak Ridge, Tennessee under consideration by the Department of Energy (DOE) for a below ground waste disposal facility. The Copper Ridge was studied for DOE to understand the influence of lithology on deep groundwater flow. Three facies types are distinguished which comprise laterally continuous, 1 to 4 m thick rock units interpreted to represent upward-shallowing depositional cycles having an apparently significant effect on groundwater flow at depth. Rock core observations indicate one of the recurring facies types is characterized by thin to medium-bedded, fine-grained dolostone with planar cryptalgal laminae and thin shaley partings. Distinctive fracturing in this facies type, that may have resulted from regional structural deformation, it considered to be responsible for weathering at depth and the development of stratabound pathways of preferred groundwater flow. In addition, geophysical data suggest that one occurrence of this weathered facies type coincides with an apparent geochemical interface at depth. Geophysical data also indicate the presence of several fluid invasion horizons, traceable outside the study area, which coincide with the unweathered occurrence of this fine-grained facies type. The subcropping of recurrent zones of preferred groundwater flow at the weathered/unweathered interface may define linear traces of enhanced aquifer recharge paralleling geologic strike. Vertical projection of these zones from the weathered/unweathered rock interface to the ground surface may describe areas of enhanced infiltration. Tests to determine the role of stratigraphic controls on groundwater flow are key components of future investigations on West Chestnut Ridge. 14 refs., 13 figs
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
International Nuclear Information System (INIS)
Delhaye, J.M.
1968-12-01
This report deals with the general equations of mass conservation, of momentum conservation, and energy conservation in the case of a two-phase flow. These equations are presented in several forms starting from integral equations which are assumed initially a priori. 1. Equations with local instantaneous variables, and interfacial conditions; 2. Equations with mean instantaneous variables in a cross-section, and practical applications: these equations include an important experimental value which is the ratio of the cross-section of passage of one phase to the total cross-section of a flow-tube. 3. Equations with a local statistical mean, and equations averaged over a period of time: A more advanced attempt to relate theory and experiment consists in taking the statistical averages of local equations. Equations are then obtained involving variables which are averaged over a period of time with the help of an ergodic assumption. 4. Combination of statistical averages and averages over a cross-section: in this study are considered the local variables averaged statistically, then averaged over the cross-section, and also the variables averaged over the section and then averaged statistically. 5. General equations concerning emulsions: In this case a phase exists in a locally very finely divided form. This peculiarity makes it possible to define a volume concentration, and to draw up equations which have numerous applications. - Certain points arising in the first part of this report concerning general mass conservation equations for two-phase flow have been completed and clarified. The terms corresponding to the interfacial tension have been introduced into the general equations. The interfacial conditions have thus been generalized. A supplementary step has still to be carried out: it has, in effect, been impossible to take the interfacial tension into account in the case of emulsions. It was then appeared interesting to compare this large group of fundamental
Identifying three-dimensional nested groundwater flow systems in a Tóthian basin
Wang, Xu-Sheng; Wan, Li; Jiang, Xiao-Wei; Li, Hailong; Zhou, Yangxiao; Wang, Junzhi; Ji, Xiaohui
2017-10-01
Nested groundwater flow systems have been revealed in Tóth's theory as the structural property of basin-scale groundwater circulation but were only well known with two-dimensional (2D) profile models. The method of searching special streamlines across stagnation points for partitioning flow systems, which has been successfully applied in the 2D models, has never been implemented for three-dimensional (3D) Tóthian basins because of the difficulty in solving the dual stream functions. Alternatively, a new method is developed to investigate 3D nested groundwater flow systems without determination of stagnation points. Connective indices are defined to quantify the connection between individual recharge and discharge zones along streamlines. Groundwater circulation cells (GWCCs) are identified according to the distribution of the connective indices and then grouped into local, intermediate and regional flow systems. This method requires existing solution of the flow velocity vector and is implemented via particle tracking technique. It is applied in a hypothetical 3D Tóthian basin with an analytical solution of the flow field and in a real-world basin with a numerical modeling approach. Different spatial patterns of flow systems compared to 2D profile models are found. The outcrops boundaries of GWCCs on water table may significantly deviate from and are not parallel to the nearby water table divides. Topological network is proposed to represent the linked recharge-discharge zones through closed and open GWCCs. Sensitivity analysis indicates that the development of GWCCs depends on the basin geometry, hydraulic parameters and water table shape.
Flow Equation Approach to the Statistics of Nonlinear Dynamical Systems
Marston, J. B.; Hastings, M. B.
2005-03-01
The probability distribution function of non-linear dynamical systems is governed by a linear framework that resembles quantum many-body theory, in which stochastic forcing and/or averaging over initial conditions play the role of non-zero . Besides the well-known Fokker-Planck approach, there is a related Hopf functional methodootnotetextUriel Frisch, Turbulence: The Legacy of A. N. Kolmogorov (Cambridge University Press, 1995) chapter 9.5.; in both formalisms, zero modes of linear operators describe the stationary non-equilibrium statistics. To access the statistics, we investigate the method of continuous unitary transformationsootnotetextS. D. Glazek and K. G. Wilson, Phys. Rev. D 48, 5863 (1993); Phys. Rev. D 49, 4214 (1994). (also known as the flow equation approachootnotetextF. Wegner, Ann. Phys. 3, 77 (1994).), suitably generalized to the diagonalization of non-Hermitian matrices. Comparison to the more traditional cumulant expansion method is illustrated with low-dimensional attractors. The treatment of high-dimensional dynamical systems is also discussed.
Yidana, Sandow Mark; Bawoyobie, Patrick; Sakyi, Patrick; Fynn, Obed Fiifi
2018-02-01
An evolutionary trend has been postulated through the analysis of hydrochemical data of a crystalline rock aquifer system in the Densu Basin, Southern Ghana. Hydrochemcial data from 63 groundwater samples, taken from two main groundwater outlets (Boreholes and hand dug wells) were used to postulate an evolutionary theory for the basin. Sequential factor and hierarchical cluster analysis were used to disintegrate the data into three factors and five clusters (spatial associations). These were used to characterize the controls on groundwater hydrochemistry and its evolution in the terrain. The dissolution of soluble salts and cation exchange processes are the dominant processes controlling groundwater hydrochemistry in the terrain. The trend of evolution of this set of processes follows the pattern of groundwater flow predicted by a calibrated transient groundwater model in the area. The data suggest that anthropogenic activities represent the second most important process in the hydrochemistry. Silicate mineral weathering is the third most important set of processes. Groundwater associations resulting from Q-mode hierarchical cluster analysis indicate an evolutionary pattern consistent with the general groundwater flow pattern in the basin. These key findings are at variance with results of previous investigations and indicate that when carefully done, groundwater hydrochemical data can be very useful for conceptualizing groundwater flow in basins.
Hydrogeochemical evidence supporting models for groundwater flow around Sellafield, U.K
International Nuclear Information System (INIS)
Metcalfe, R.; Milodowski, A.E.; Noy, D.J.
1999-01-01
Recently, United Kingdom Nirex Limited has investigated a site near Sellafield, north-west England to assess its suitability as the potential location for a deep underground repository for the disposal of intermediate- level, and some low-level, solid radioactive waste. Groundwater flow at the site was simulated using a variety of computer codes, based upon conceptual models of the hydrogeological system. Chemical data for groundwaters aided the development of these conceptual models, and also provided a check upon the computer models' validity. Mineralogical information can be accommodated within the conceptual and theoretical framework. The results of the investigation are presented. (author)
Linking stream flow and groundwater to avian habitat in a desert riparian system.
Merritt, David M; Bateman, Heather L
2012-10-01
Increasing human populations have resulted in aggressive water development in arid regions. This development typically results in altered stream flow regimes, reduced annual flow volumes, changes in fluvial disturbance regimes, changes in groundwater levels, and subsequent shifts in ecological patterns and processes. Balancing human demands for water with environmental requirements to maintain functioning ecosystems requires quantitative linkages between water in streams and ecosystem attributes. Streams in the Sonoran Desert provide important habitat for vertebrate species, including resident and migratory birds. Habitat structure, food, and nest-building materials, which are concentrated in riparian areas, are provided directly or indirectly by vegetation. We measured riparian vegetation, groundwater and surface water, habitat structure, and bird occurrence along Cherry Creek, a perennial tributary of the Salt River in central Arizona, USA. The purpose of this work was to develop an integrated model of groundwater-vegetation-habitat structure and bird occurrence by: (1) characterizing structural and provisioning attributes of riparian vegetation through developing a bird habitat index (BHI), (2) validating the utility of our BHI through relating it to measured bird community composition, (3) determining the riparian plant species that best explain the variability in BHI, (4) developing predictive models that link important riparian species to fluvial disturbance and groundwater availability along an arid-land stream, and (5) simulating the effects of changes in flow regime and groundwater levels and determining their consequences for riparian bird communities. Riparian forest and shrubland vegetation cover types were correctly classified in 83% of observations as a function of fluvial disturbance and depth to water table. Groundwater decline and decreased magnitude of fluvial disturbance caused significant shifts in riparian cover types from riparian forest to
International Nuclear Information System (INIS)
Santiago, M.F.; Reboucas, A.C.; Frischkorn, H.
1986-01-01
Two different approaches are made: an isotope model, based on the observation of the 180/160 ratio of the water, and an hydrochemical model, using the Cl - concentration, are described and applied to determine the evaporation and groundwater flow rates from or to dams. During a period of three years the dams Pereira de Miranda and Caxitore in Pentecostes - Ceara-Brazil (80 Km west of Fortaleza), located in the Precambrian cristalline rock area, were studies. The results show that the models have a good applicability, to estimate the average daily depth of evaporation from free-water surfaces, from nearby porous media or the groundwater inflow or outflow. (author) [pt
Mansour, M M; Spink, A E F
2013-01-01
Grid refinement is introduced in a numerical groundwater model to increase the accuracy of the solution over local areas without compromising the run time of the model. Numerical methods developed for grid refinement suffered certain drawbacks, for example, deficiencies in the implemented interpolation technique; the non-reciprocity in head calculations or flow calculations; lack of accuracy resulting from high truncation errors, and numerical problems resulting from the construction of elongated meshes. A refinement scheme based on the divergence theorem and Taylor's expansions is presented in this article. This scheme is based on the work of De Marsily (1986) but includes more terms of the Taylor's series to improve the numerical solution. In this scheme, flow reciprocity is maintained and high order of refinement was achievable. The new numerical method is applied to simulate groundwater flows in homogeneous and heterogeneous confined aquifers. It produced results with acceptable degrees of accuracy. This method shows the potential for its application to solving groundwater heads over nested meshes with irregular shapes. © 2012, British Geological Survey © NERC 2012. Ground Water © 2012, National GroundWater Association.
Groundwater flow and potential effects on evaporite dissolution in the Paradox Basin, SE Utah
Reitman, N.; Ge, S.; Mueller, K. J.
2012-12-01
A hydrogeologic study was conducted in the portion of the Paradox Basin south of the Needles District of Canyonlands National Park, Utah. Geology of the study area comprises fractured and faulted Paleozoic sandstone, limestone, and shale, which are underlain by evaporite cycles of the Paradox Formation. The evaporite deposits deform and dissolve when they come in contact with groundwater, generating land subsidence, saline groundwater, and salt input to the Colorado River. Active faults in the region slip at a rate of approximately 2 mm/year, likely due to evaporite dissolution. The objective of this study is to better understand groundwater flow and solute transport dynamics and to help determine the rate and timing of subsurface salt dissolution, which is an important control on the salt tectonics in the region. Study methods include hydrologic fieldwork, laboratory tests, and numerical modeling. No groundwater wells exist in the study area. Water samples from springs and seeps were collected throughout the study area. Analysis of total dissolved solids (TDS), stable oxygen (δ18O) and deuterium (δD) isotopes, spring and seep locations, and prior data are used to gain a preliminary understanding of the shallow groundwater flow in the region. Stable isotope ratios of oxygen (18O/16O) and deuterium (D/H) are used to constrain the source of spring water. Measured δ values are compared to predicted δ values for precipitation from WaterIsotopes.org for each sample site. Measured isotopic values range from -14.9 ‰ to -10.7 ‰ for δ18O and -108 ‰ to -78 ‰ for δD. The majority of samples from above 2000 m match predicted isotopic values for precipitation. Most samples taken below 2000 m are lighter than predicted isotopic values for precipitation. The TDS of spring samples measured in the lab show they range from 184 mg/L to 1552 mg/L with the majority of samples between 220 - 430 mg/L. TDS shows a weak correlation (R2 = 0.54) with altitude, where lower TDS
Energy Technology Data Exchange (ETDEWEB)
Jussila, P
1999-11-01
Modelling groundwater flow is an essential part of the safety assessment of spent fuel disposal because moving groundwater makes a physical connection between a geological repository and the biosphere. Some of the common approaches to model groundwater flow in bedrock are equivalent porous continuum (EC), stochastic continuum and various fracture network concepts. The actual flow system is complex and measuring data are limited. Multiple distinct approaches and models, alternative scenarios as well as calibration and sensitivity analyses are used to give confidence on the results of the calculations. The correctness and orders of magnitude of results of such complex research can be assessed by comparing them to the results of simplified and robust approaches. The first part of this study is a survey of the objects, contents and methods of the groundwater flow modelling performed in the safety assessment of the spent fuel disposal in Finland and Sweden. The most apparent difference of the Swedish studies compared to the Finnish ones is the approach of using more different models, which is enabled by the more resources available in Sweden. The results of more comprehensive approaches provided by international co-operation are very useful to give perspective to the results obtained in Finland. In the second part of this study, the influence of boundary conditions on the flow fields of a simple 2D model is examined. The assumptions and simplifications in this approach include e.g. the following: (1) the EC model is used, in which the 2-dimensional domain is considered a continuum of equivalent properties without fractures present, (2) the calculations are done for stationary fields, without sources or sinks present in the domain and with a constant density of the groundwater, (3) the repository is represented by an isotropic plate, the hydraulic conductivity of which is given fictitious values, (4) the hydraulic conductivity of rock is supposed to have an exponential
Numerical modeling of groundwater flow in the coastal aquifer system of Taranto (southern Italy)
De Filippis, Giovanna; Giudici, Mauro; Negri, Sergio; Margiotta, Stefano; Cattaneo, Laura; Vassena, Chiara
2014-05-01
The Mediterranean region is characterized by a strong development of coastal areas with a high concentration of water-demanding human activities, resulting in weakly controlled withdrawals of groundwater which accentuate the saltwater intrusion phenomenon. The worsening of groundwater quality is a huge problem especially for those regions, like Salento (southern Italy), where a karst aquifer system represents the most important water resource because of the deficiency of a well developed superficial water supply. In this frame, the first 2D numerical model describing the groundwater flow in the karst aquifer of Salento peninsula was developed by Giudici et al. [1] at the regional scale and then improved by De Filippis et al. [2]. In particular, the estimate of the saturated thickness of the deep aquifer highlighted that the Taranto area is particularly sensitive to the phenomenon of seawater intrusion, both for the specific hydrostratigraphic configuration and for the presence of highly water-demanding industrial activities. These remarks motivate a research project which is part of the research program RITMARE (The Italian Research for the Sea), within which a subprogram is specifically dedicated to the problem of the protection and preservation of groundwater quality in Italian coastal aquifers and in particular, among the others, in the Taranto area. In this context, the CINFAI operative unit aims at providing a contribution to the characterization of groundwater in the study area. The specific objectives are: a. the reconstruction of the groundwater dynamic (i.e., the preliminary identification of a conceptual model for the aquifer system and the subsequent modeling of groundwater flow in a multilayered system which is very complex from the hydrostratigraphical point of view); b. the characterization of groundwater outflows through submarine and subaerial springs and the water exchanges with the shallow coastal water bodies (e.g. Mar Piccolo) and the off
International Nuclear Information System (INIS)
Aoki, Hiroomi; Shimomura, Masanori; Kawakami, Hiroto; Suzuki, Shunichi
2011-01-01
In safety assessments of radioactive waste disposal facilities, ground water flow analysis are used for calculating the radionuclide transport pathway and the infiltration flow rate of groundwater into the disposal facilities. For this type of calculations, the mixed hybrid finite element method has been used and discussed about the accuracy of ones in Europe. This paper puts great emphasis on the infiltration flow rate of groundwater into the disposal facilities, and describes the accuracy of results obtained from mixed hybrid finite element method by comparing of local water mass conservation and the reliability of the element breakdown numbers among the mixed hybrid finite element method, finite volume method and nondegenerated finite element method. (author)
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
Evaluation of influence of splay fault growth on groundwater flow around geological disposal system
International Nuclear Information System (INIS)
Takai, Shizuka; Takeda, Seiji; Sakai, Ryutaro; Shimada, Taro; Munakata, Masahiro; Tanaka, Tadao
2017-01-01
In geological disposal, the direct effect of active faults on geological repositories is avoided at the stage of site characterization, however, uncertainty remains for the avoidance of faults derived from active faults, which are concealed deep under the ground and are difficult to detect by site investigation. In this research, the influence of the growth of undetected splay faults on a natural barrier in a geological disposal system due to the future action of faults was evaluated. We investigated examples of splay faults in Japan and set conditions for the growth of splay faults. Furthermore, we assumed a disposal site composed of sedimentary rock and made a hydrogeological model of the growth of splay faults. We carried out groundwater flow analyses, changing parameters such as the location and depth of the repository and the growth velocity of splay faults. We carried out groundwater flow analyses, changing parameters such as the location and depth of the repository and the growth velocity of splay faults. The results indicate that the main flow path from the repository is changed into an upward flow along the splay fault due to its growth and that the average velocity to the ground surface becomes one or two orders of magnitude higher than that before its growth. The results also suggest that splay fault growth leads to the possibility of the downward flow of oxidizing groundwater from the ground surface area. (author)
Cash flow in the context of economic equation of continuity
Directory of Open Access Journals (Sweden)
Fernando Gómez Villarraga
2006-07-01
Full Text Available The mathematic scheme, known as economic equation of continuity, is established for the balance of economic resources. In order to apply this equation it is necessary to determine an economic volume of control. The patrimonial equation is also proposed as a speed equationfor this volurne. The integral equation of economic continuity is applied to the «cash» system along with the integral patrimonial equation and so it gets expressions that correspond to model to elaborate cashflow statement with the particularities of the direct and indirect method. This model generales a useful definition for the calculation of this basic financial statement classified by operating, investing and financing activities.
Flow pathways in the evolving critical zone - insights from hydraulic groundwater theory
Harman, C. J.; Cosans, C.; Kim, M.
2017-12-01
The geochemical signatures of the evolving critical zone are delivered into streams via saturated lateral flow through hillslopes. Here we will draw on hydraulic groundwater theory and scaling arguments to obtain insights into the first-order controls on the transition from vertical infiltration to lateral flow in the critical zone. Hydraulic groundwater theory aims to provide a simplified description of unconfined, saturated groundwater flow in systems that are substantially larger in lateral than vertical extent. The theory rests on the Dupuit assumptions, which are often erroneously stated as including an assumption of exclusively lateral flow. In fact the full three-dimensional flow field can be approximated from these assumptions. Building on this theory, we examine how overall hillslope structure (slope, permeability, convergence/divergence etc.) determines the direction and magnitude of flow in the vicinity of weathering fronts in the critical zone, and how weathering products are delivered to the hillslope base. The results demonstrate that under certain conditions the mere presence of lateral flow will not disturb the lateral symmetry of reaction fronts along the hillslope. Furthermore, coupling to a simple reaction model with porosity/permeability feedback allows us to examine the implications for weathering front advance where saturated lateral flow occurs as a transient perched aquifer at the weathering front. The overall rate of weathering front advance is found to be primarily determined by the component of flow normal to the weathering front, and only significantly accelerated by the lateral component above the weathering front when parent rock permeability is very low.
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
Document available in extended abstract form only. In Belgium, the Boom Clay formation is considered as reference host rock for the geological disposal of radioactive waste. Aquifers surrounding the Boom Clay play a passive role in the context of the disposal safety whereby the radionuclides are diluted by groundwater flow. The groundwater flow in these aquifers has been studied since decades. This research involves observations of groundwater levels in the regional and local piezo-metric networks, several site investigations including geophysics and core-drilled boreholes and groundwater modelling. In this context, groundwater modelling represents the integration of the site characterization efforts and provides a comprehensive tool for constraining the models used in the safety assessment of the geological disposal. Since 1985, groundwater levels are observed monthly in the regional piezo-metric network. It consists of 142 filters monitoring the groundwater levels at 45 sites. Along with the observed groundwater levels from the local piezo-metric network (concentrated around the Mol-Dessel site for surface disposal), these data provide an excellent insight into the evolution of the groundwater levels. Moreover, they represent a calibration (validation) dataset for groundwater flow modelling. The groundwater system forming the environment of the Boom Clay host rock was characterized during several site investigation campaigns, within which seven core-drilled boreholes were realized, whereby hydraulic parameters and hydro-stratigraphy of the groundwater system could be collected. The dataset obtained from the above mentioned campaigns was complemented by archived data on hydraulic testing in the aquifers in order to build a comprehensive groundwater model integrating these data into a single numerical representation of the groundwater system. Three regional groundwater models have been developed integrating the site characterization data collected in the north
Saad, D.A.; Thorstenson, D.C.
1998-01-01
Water-quality and geohydrologic data were collected from 19 monitor wells and a stream in an agricultural area in southeastern Wisconsin. These sites were located along a 2,700-ft transect from a local ground-water high to the stream. The transect is approximately parallel to the horizontal direction of ground-water flow at the water table. Most of the wells were installed in unconsolidated deposits at five locations along the transect and include an upgradient well nest, a midgradient well nest, a downgradient well nest, wells in the lowland area near the stream, and wells installed in the stream bottom. The data collected from this study site were used to describe the water quality and geohydrology of the area and to explain and model the variations in water chemistry along selected ground-water flowpaths.
Sakakibara, Koichi; Tsujimura, Maki; Song, Xianfang; Zhang, Jie
2014-05-01
Groundwater recharge is a crucial hydrological process for effective water management especially in arid/ semi-arid regions. However, the insufficient number of specific research regarding groundwater recharge process has been reported previously. Intensive field surveys were conducted during rainy season, mid dry season, and end of dry season, in order to clarify comprehensive groundwater recharge and flow regime of Wangkuai watershed in a headwater, which is a main recharge zone of North China Plain. The groundwater, spring, stream water and lake water were sampled, and inorganic solute constituents and stable isotopes of oxygen 18 and deuterium were determined on all water samples. Also the stream flow rate was observed. The solute ion concentrations and stable isotopic compositions show that the most water of this region can be characterized by Ca-HCO3 type and the main water source is precipitation which is affected by altitude effect of stable isotopes. In addition, the river and reservoir of the area seem to recharge the groundwater during rainy season, whereas interaction between surface water and groundwater does not become dominant gradually after the rainy season. The inversion analysis applied in Wangkuai watershed using simple mixing model represents an existing multi-flow systems which shows a distinctive tracer signal and flow rate. In summary, the groundwater recharged at different locations in the upper stream of Wangkuai reservoir flows downward to alluvial fan with a certain amount of mixing together, also the surface water recharges certainly the groundwater in alluvial plain in the rainy season.
A laboratory scale analysis of groundwater flow and salinity distribution in the Aespoe area
International Nuclear Information System (INIS)
Svensson, Urban
1999-12-01
This report concerns a study which was conducted for SKB. The conclusions and viewpoints presented in the report are those of the author(s) and do not necessarily coincide with those of the client. The objective of the study is to develop, calibrate and apply a numerical simulation model of the Aespoe Hard Rock Laboratory (HRL). An area of 800 x 600 centred around the HRL, gives the horizontal extent of the model. In the vertical direction the model covers the depth interval from 200 to 560 metres. The model is based on a mathematical model that includes equations for the Darcy velocities, mass conservation and salinity distribution. Gravitational effects are thus fully accounted for. A site scale groundwater model was used to generate boundary conditions for all boundaries. Transmissivities of major fracture zones are based on field data. Fractures and fracture zones with a length scale between 5 and 320 metres are accounted for by a novel method that is based on a discrete fracture network. A small background conductivity is added to account for fractures smaller than the grid size, which is metres. A calibration of the model is carried out, using field data from the Aespoe HRL. A satisfactory agreement with field data is obtained. Main results from the model include vertical and horizontal sections of flow, salinity and hydraulic head distributions for completed tunnel. A sensitivity study, where the properties of the conductivity field are modified, is also carried out. The general conclusion of the study is that the model developed can simulate the conditions at the Aespoe HRL in a realistic manner
Hill, Mary C.; Faunt, Claudia C.; Belcher, Wayne; Sweetkind, Donald; Tiedeman, Claire; Kavetski, Dmitri
2013-01-01
This work demonstrates how available knowledge can be used to build more transparent and refutable computer models of groundwater systems. The Death Valley regional groundwater flow system, which surrounds a proposed site for a high level nuclear waste repository of the United States of America, and the Nevada National Security Site (NNSS), where nuclear weapons were tested, is used to explore model adequacy, identify parameters important to (and informed by) observations, and identify existing old and potential new observations important to predictions. Model development is pursued using a set of fundamental questions addressed with carefully designed metrics. Critical methods include using a hydrogeologic model, managing model nonlinearity by designing models that are robust while maintaining realism, using error-based weighting to combine disparate types of data, and identifying important and unimportant parameters and observations and optimizing parameter values with computationally frugal schemes. The frugal schemes employed in this study require relatively few (10–1000 s), parallelizable model runs. This is beneficial because models able to approximate the complex site geology defensibly tend to have high computational cost. The issue of model defensibility is particularly important given the contentious political issues involved.
The movement of groundwater flow in unsaturated fractured porous medium
International Nuclear Information System (INIS)
Li Jinxuan
1995-01-01
The author analyses the fundamental processes governing infiltration in fractured porous rock. Asymptotic solutions for the front movement are given for each flow period and comparisons with numerical solutions are made. The result of the study is relevant to nuclear waste storage, hazardous waste disposal and petroleum recovery
International Nuclear Information System (INIS)
Md Shahid Ayub; Roslan Mohd Ali; Kamarudin Samuding
1996-01-01
The filtration velocity of the groundwater was determine by introducing I mCi Br-82 into a borehole. Br-82 was in the form of potassium bromide. The result showed that the filtration velocity varies from 2.3 to 4.5 cm/day depending on the soil matrix with the clayey layer posting more resistance to flow. Au-198 in the form of aurium chloride was introduce into two other boreholes to determine the direction of flow. The general trend of flow was in the direction between N140E and N160E
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
Evaluation of bias associated with capture maps derived from nonlinear groundwater flow models
Nadler, Cara; Allander, Kip K.; Pohll, Greg; Morway, Eric D.; Naranjo, Ramon C.; Huntington, Justin
2018-01-01
The impact of groundwater withdrawal on surface water is a concern of water users and water managers, particularly in the arid western United States. Capture maps are useful tools to spatially assess the impact of groundwater pumping on water sources (e.g., streamflow depletion) and are being used more frequently for conjunctive management of surface water and groundwater. Capture maps have been derived using linear groundwater flow models and rely on the principle of superposition to demonstrate the effects of pumping in various locations on resources of interest. However, nonlinear models are often necessary to simulate head-dependent boundary conditions and unconfined aquifers. Capture maps developed using nonlinear models with the principle of superposition may over- or underestimate capture magnitude and spatial extent. This paper presents new methods for generating capture difference maps, which assess spatial effects of model nonlinearity on capture fraction sensitivity to pumping rate, and for calculating the bias associated with capture maps. The sensitivity of capture map bias to selected parameters related to model design and conceptualization for the arid western United States is explored. This study finds that the simulation of stream continuity, pumping rates, stream incision, well proximity to capture sources, aquifer hydraulic conductivity, and groundwater evapotranspiration extinction depth substantially affect capture map bias. Capture difference maps demonstrate that regions with large capture fraction differences are indicative of greater potential capture map bias. Understanding both spatial and temporal bias in capture maps derived from nonlinear groundwater flow models improves their utility and defensibility as conjunctive-use management tools.
Chen, Po-Chia; Chuang, Mo-Hsiung; Tan, Yih-Chi
2014-05-01
In recent years the urban and industrial developments near the coastal area are rapid and therefore the associated population grows dramatically. More and more water demand for human activities, agriculture irrigation, and aquaculture relies on heavy pumping in coastal area. The decline of groundwater table may result in the problems of seawater intrusion and/or land subsidence. Since the 1950s, numerous studies focused on the effect of tidal fluctuation on the groundwater flow in the coastal area. Many studies concentrated on the developments of one-dimensional (1D) and two-dimensional (2D) analytical solutions describing the tide-induced head fluctuations. For example, Jacob (1950) derived an analytical solution of 1D groundwater flow in a confined aquifer with a boundary condition subject to sinusoidal oscillation. Jiao and Tang (1999) derived a 1D analytical solution of a leaky confined aquifer by considered a constant groundwater head in the overlying unconfined aquifer. Jeng et al. (2002) studied the tidal propagation in a coupled unconfined and confined costal aquifer system. Sun (1997) presented a 2D solution for groundwater response to tidal loading in an estuary. Tang and Jiao (2001) derived a 2D analytical solution in a leaky confined aquifer system near open tidal water. This study aims at developing a general analytical solution describing the head fluctuations in a 2D estuarine aquifer system consisted of an unconfined aquifer, a confined aquifer, and an aquitard between them. Both the confined and unconfined aquifers are considered to be anisotropic. The predicted head fluctuations from this solution will compare with the simulation results from the MODFLOW program. In addition, the solutions mentioned above will be shown to be special cases of the present solution. Some hypothetical cases regarding the head fluctuation in costal aquifers will be made to investigate the dynamic effects of water table fluctuation, hydrogeological conditions, and
Flow and discharge of groundwater from a snowmelt-affected sandy beach
Chaillou, G.; Lemay-Borduas, F.; Larocque, M.; Couturier, M.; Biehler, A.; Tommi-Morin, G.
2018-02-01
The study is based on a complex and unique data set of water stable isotopes (i.e., δ18O and δ2H), radon-222 activities (i.e., 222Rn) and groundwater levels to better understand the interaction of fresh groundwater and recirculated seawater in a snowmelt-affected subterranean estuary (STE) in a boreal region (Îles-de-la-Madeleine, Qc, Canada). By using a combination of hydrogeological and marine geochemical approaches, the objective was to analyze and quantify submarine groundwater discharge processes through a boreal beach after the snow melt period, in early June. The distribution of δ18O and δ2H in beach groundwater showed that inland fresh groundwater contributed between 97 and 30% of water masses presented within the STE. A time series of water table levels during the 16 days of the study indicated that tides propagated as a dynamic wave limiting the mass displacement of seawater within the STE. This up-and-down movement of the water table (∼10-30 cm) induced the vertical infiltration of seawater at the falling tide. At the front of the beach, a radon-based mass balance calculated with high-resolution 222Rn survey estimated total SGD of 3.1 m3/m/d at the discharge zone and a mean flow to 1.5 m3/m/d in the bay. The nearshore discharge agreed relatively well with Darcy fluxes calculated at the beach face. Fresh groundwater makes up more than 50% of the total discharge during the measuring campaign. These results indicate that beaches in boreal and cold regions could be important sources of freshwater originate and groundwater-borne solutes and contaminants to the marine environment after the snowmelt.
Groundwater flow analysis using radon-222 existing in environment as an indicator
International Nuclear Information System (INIS)
Komae, Takami
1996-01-01
Several kinds of isotopes have been used to trace water movement in the hydrology including surface and ground water as indicators. But those are not effective to analyze the contaminant movement with groundwater though short distance in short time owing to long life. Radon ( 222 Rn) existing in environment was chosen for this purpose as an short-lived indicator. Radon is a radioactive gas, with a half life of 3.8 days, generated from radium ( 226 Ra) in strata. Radon concentration in groundwater increases to reach an equilibrated value within about three weeks after infiltrating underground. The equilibrated concentration becomes an own value of the aquifer depending on the radium content, the grain size and porosity of aquifer. The characteristic makes it able to identify aquifers and sub basins. Since radon concentration in groundwater is 100 to 1000 times as high as that in surface water, groundwater and surface water interaction is quantitatively analyzed. A liquid scintillation counter was employed to measure radon concentration after extracting radon in water to toluene. We applied those advantage of radon-222 to various field investigations and discussed the applicability. It was really possible to analyze the groundwater flow. Monitoring radon concentration in pumped water, occurrences of squeeze and leakage from the different aquifer were detected. Main aquifer was easily determined from the vertical distribution of radon concentration in bore hole. In the injection test using surface water, the spread of injected water was confirmed by the decrease of radon concentration in bore hole water. The radon method was useful to analyze the dam leakage, effluent seepage of groundwater in river, influent seepage of river water underground, and groundwater recharge with irrigation water through unsaturated zone. (author)
Updated comparison of groundwater flow model results and isotopic data in the Leon Valley, Mexico
Hernandez-Garcia, G. D.
2015-12-01
Northwest of Mexico City, the study area is located in the State of Guanajuato. Leon Valley has covered with groundwater its demand of water, estimated in 20.6 cubic meters per second. The constant increase of population and economic activities in the region, mainly in cities and automobile factories, has also a constant growth in water needs. Related extraction rate has produced an average decrease of approximately 1.0 m per year over the past two decades. This suggests that the present management of the groundwater should be checked. Management of groundwater in the study area involves the possibility of producing environmental impacts by extraction. This vital resource under stress becomes necessary studying its hydrogeological functioning to achieve scientific management of groundwater in the Valley. This research was based on the analysis and integration of existing information and the field generated by the authors. On the base of updated concepts like the geological structure of the area, the hydraulic parameters and the composition of deuterium-delta and delta-oxygen -18, this research has new results. This information has been fully analyzed by applying a groundwater flow model with particle tracking: the result has also a similar result in terms of travel time and paths derived from isotopic data.
Regularity of the 3D Navier-Stokes equations with viewpoint of 2D flow
Bae, Hyeong-Ohk
2018-04-01
The regularity of 2D Navier-Stokes flow is well known. In this article we study the relationship of 3D and 2D flow, and the regularity of the 3D Naiver-Stokes equations with viewpoint of 2D equations. We consider the problem in the Cartesian and in the cylindrical coordinates.
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
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)
A Note on Unsteady Temperature Equation For Gravity Flow of A ...
African Journals Online (AJOL)
We present an analytical study of unsteady temperature energy equation for gravity of a fluid with non – Newtonian behaviour through a porous medium. For the case of radial axisymmetric flow, the governing partial differential equation is transformed into an ordinary differential equation through similarity variables.
Basic equations of interfacial area transport in gas-liquid two-phase flow
International Nuclear Information System (INIS)
Kataoka, I.; Yoshida, K.; Naitoh, M.; Okada, H.; Morii, T.
2011-01-01
The rigorous and consistent formulations of basic equations of interfacial area transport were derived using correlation functions of characteristic function of each phase and velocities of each phase. Turbulent transport term of interfacial area concentration was consistently derived and related to the difference between interfacial velocity and averaged velocity of each phase. Constitutive equations of turbulent transport terms of interfacial area concentration were proposed for bubbly flow. New transport model and constitutive equations were developed for churn flow. These models and constitutive equations are validated by experimental data of radial distributions of interfacial area concentration in bubbly and churn flow. (author)
Research on fracture analysis, groundwater flow and sorption processes in fractured rocks
Energy Technology Data Exchange (ETDEWEB)
Lee, Dae Ha [Korea Institute of Geology Mining and Materials, Taejon (Korea)
1998-12-01
Due to increasing demand for numerous industrial facilities including nuclear power plants and waste repositories, the feasibility of rocks masses as sites for the facilities has been a geological issue of concern. Rock masses, in general, comprises systems of fractures which can provide pathways for groundwater flow and may also affect the stability of engineered structures. such properties of fractures stimulate a synthetic study on (1) analyses of fracture systems, and (2) characterization of groundwater flow and sorption processes in fractured rocks to establish a preliminary model for assessing suitable sites for industrial facilities. The analyses of fracture systems cover (1) reconstruction of the Cenozoic tectonic movements and estimation of frequency indices for the Holocene tectonic movements, (2) determination of distributions and block movements of the Quaternary marine terraces, (3) investigation of lithologic and geotechnical nature of study area, and (4) examination of the Cenozoic volcanic activities and determination of age of the dike swarms. Using data obtained from above mentioned analyses along with data related to earthquakes and active faults, probabilistic approach is performed to determine various potential hazards which may result from the Quaternary or the Holocene tectonic movements. In addition, stepwise and careful integration of various data obtained from field works and laboratory experiments are carried out to analyze groundwater flow in fractures rocks as follows; (1) investigation of geological feature of the site, (2) identification and characterization of fracture systems using core and televiewer logs, (3) determination of conductive fractures using electrical conductivity, temperature, and flow logs, (4) identification of hydraulic connections between fractures using televiewer logs with tracer tests within specific zones. The results obtained from these processes allow a qualitative interpretation of groundwater flow patterns
Computational issues of solving the 1D steady gradually varied flow equation
Directory of Open Access Journals (Sweden)
Artichowicz Wojciech
2014-09-01
Full Text Available In this paper a problem of multiple solutions of steady gradually varied flow equation in the form of the ordinary differential energy equation is discussed from the viewpoint of its numerical solution. Using the Lipschitz theorem dealing with the uniqueness of solution of an initial value problem for the ordinary differential equation it was shown that the steady gradually varied flow equation can have more than one solution. This fact implies that the nonlinear algebraic equation approximating the ordinary differential energy equation, which additionally coincides with the wellknown standard step method usually applied for computing of the flow profile, can have variable number of roots. Consequently, more than one alternative solution corresponding to the same initial condition can be provided. Using this property it is possible to compute the water flow profile passing through the critical stage.
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
Chen, Mingjie; Izady, Azizallah; Abdalla, Osman A.; Amerjeed, Mansoor
2018-02-01
Bayesian inference using Markov Chain Monte Carlo (MCMC) provides an explicit framework for stochastic calibration of hydrogeologic models accounting for uncertainties; however, the MCMC sampling entails a large number of model calls, and could easily become computationally unwieldy if the high-fidelity hydrogeologic model simulation is time consuming. This study proposes a surrogate-based Bayesian framework to address this notorious issue, and illustrates the methodology by inverse modeling a regional MODFLOW model. The high-fidelity groundwater model is approximated by a fast statistical model using Bagging Multivariate Adaptive Regression Spline (BMARS) algorithm, and hence the MCMC sampling can be efficiently performed. In this study, the MODFLOW model is developed to simulate the groundwater flow in an arid region of Oman consisting of mountain-coast aquifers, and used to run representative simulations to generate training dataset for BMARS model construction. A BMARS-based Sobol' method is also employed to efficiently calculate input parameter sensitivities, which are used to evaluate and rank their importance for the groundwater flow model system. According to sensitivity analysis, insensitive parameters are screened out of Bayesian inversion of the MODFLOW model, further saving computing efforts. The posterior probability distribution of input parameters is efficiently inferred from the prescribed prior distribution using observed head data, demonstrating that the presented BMARS-based Bayesian framework is an efficient tool to reduce parameter uncertainties of a groundwater system.
Simulation of groundwater and surface-water flow in the upper Deschutes Basin, Oregon
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
Valder, Joshua F.; Delzer, Gregory C.; Carter, Janet M.; Smith, Bruce D.; Smith, David V.
2016-09-28
The city of Sioux Falls is the fastest growing community in South Dakota. In response to this continued growth and planning for future development, Sioux Falls requires a sustainable supply of municipal water. Planning and managing sustainable groundwater supplies requires a thorough understanding of local groundwater resources. The Big Sioux aquifer consists of glacial outwash sands and gravels and is hydraulically connected to the Big Sioux River, which provided about 90 percent of the city’s source-water production in 2015. Managing sustainable groundwater supplies also requires an understanding of groundwater availability. An effective mechanism to inform water management decisions is the development and utilization of a groundwater-flow model. A groundwater-flow model provides a quantitative framework for synthesizing field information and conceptualizing hydrogeologic processes. These groundwater-flow models can support decision making processes by mapping and characterizing the aquifer. Accordingly, the city of Sioux Falls partnered with the U.S. Geological Survey to construct a groundwater-flow model. Model inputs will include data from advanced geophysical techniques, specifically airborne electromagnetic methods.
Deming, D.; Sass, J.H.; Lachenbruch, A.H.; De Rito, R. F.
1992-01-01
Several high-resolution temperature logs were made in each of 21 drillholes and a total of 601 thermal conductivity measurements were made on drill cuttings and cores. Near-surface heat flow (??20%) is inversely correlated with elevation and ranges from a low of 27 mW/m2 in the foothills of the Brooks Range in the south, to a high of 90 mW/m2 near the north coast. Subsurface temperatures and thermal gradients estimated from corrected BHTs are similarly much higher on the coastal plain than in the foothills province to the south. Significant east-west variation in heat flow and subsurface temperature is also observed; higher heat flow and temperature coincide with higher basement topography. The observed thermal pattern is consistent with forced convection by a topographically driven ground-water flow system. Average ground-water (Darcy) velocity in the postulated flow system is estimated to be of the order of 0.1 m/yr; the effective basin-scale permeability is estimated to be of the order of 10-14 m2. -from Authors
Johnson, Raymond H.; DeWitt, Ed; Wirt, Laurie; Arnold, L. Rick; Horton, John D.
2011-01-01
The National Park Service (NPS) seeks additional information to better understand the source(s) of groundwater and associated groundwater flow paths to Montezuma Well in Montezuma Castle National Monument, central Arizona. The source of water to Montezuma Well, a flowing sinkhole in a desert setting, is poorly understood. Water emerges from the middle limestone facies of the lacustrine Verde Formation, but the precise origin of the water and its travel path are largely unknown. Some have proposed artesian flow to Montezuma Well through the Supai Formation, which is exposed along the eastern margin of the Verde Valley and underlies the Verde Formation. The groundwater recharge zone likely lies above the floor of the Verde Valley somewhere to the north or east of Montezuma Well, where precipitation is more abundant. Additional data from groundwater, surface water, and bedrock geology are required for Montezuma Well and the surrounding region to test the current conceptual ideas, to provide new details on the groundwater flow in the area, and to assist in future management decisions. The results of this research will provide information for long-term water resource management and the protection of water rights.
Reference population equations using peak expiratory flow meters ...
African Journals Online (AJOL)
Many formulae for predicting lung function values for Nigerians have been produced by a lot of investigators. The same principle but different statistical methods were adopted by different authors in generating these equations, hence the variability observed among these formulae. Most equations in current use are based on ...
Gordon, R.; Lautz, L. K.; McKenzie, J. M.; Mark, B. G.; Chavez, D.
2013-12-01
Melting tropical glaciers supply approximately half of dry season stream discharge in glacierized valleys of the Cordillera Blanca, Peru. The remainder of streamflow originates as groundwater stored in alpine meadows, moraines and talus slopes. A better understanding of the dynamics of alpine groundwater, including sources and contributions to streamflow, is important for making accurate estimates of glacial inputs to the hydrologic budget, and for our ability to make predictions about future water resources as glaciers retreat. Our field study, conducted during the dry season in the Llanganuco valley, focused on a 0.5-km2 alpine meadow complex at 4400 m elevation, which includes talus slopes, terminal moraines, and a debris fan. Two glacial lakes and springs throughout the complex feed a network of stream channels that flow across the meadow (~2 km total length). We combined tracer measurements of stream and spring discharge and groundwater-surface water exchange with synoptic sampling of water isotopic and geochemical composition, in order to characterize and quantify contributions to streamflow from different geomorphic features. Surface water inputs to the stream channels totaled 58 l/s, while the stream gained an additional 57 l/s from groundwater inputs. Water chemistry is primarily controlled by flowpath type (surface/subsurface) and length, as well as bedrock lithology, while stable water isotopic composition appears to be controlled by water source (glacial lake, meadow or deep groundwater). Stream water chemistry is most similar to meadow groundwater springs, but isotopic composition suggests that the majority of stream water, which issues from springs at the meadow/fan interface, is from the same glacial source as the up-gradient lake. Groundwater sampled from piezometers in confined meadow aquifers is unique in both chemistry and isotopic composition, but does not contribute a large percentage of stream water exiting this small meadow, as quantified by
Groundwater flow modelling under ice sheet conditions in Greenland (phase II)
International Nuclear Information System (INIS)
Jaquet, Olivier; Namar, Rabah; Siegel, Pascal; Jansson, Peter
2012-11-01
Within the framework of the GAP project, this second phase of geosphere modelling has enabled the development of an improved regional model that has led to a better representation of groundwater flow conditions likely to occur under ice sheet conditions. New data in relation to talik geometry and elevation, as well as to deformation zones were integrated in the geosphere model. In addition, more realistic hydraulic properties were considered for geosphere modelling; they were taken from the Laxemar site in Sweden. The geological medium with conductive deformation zones was modelled as a 3D continuum with stochastically hydraulic properties. Surface and basal glacial meltwater rates provided by a dynamic ice sheet model were assimilated into the groundwater flow model using mixed boundary conditions. The groundwater flow system is considered to be governed by infiltration of glacial meltwater in heterogeneous faulted crystalline rocks in the presence of permafrost and taliks. The characterisation of the permafrost-depth distribution was achieved using a coupled description of flow and heat transfer under steady state conditions. Using glaciological concepts and satellite data, an improved stochastic model was developed for the description at regional scale for the subglacial permafrost distribution in correlation with ice velocity and bed elevation data. Finally, the production of glacial meltwater by the ice sheet was traced for the determination of its depth and lateral extent. The major improvements are related to the type and handling of the subglacial boundary conditions. The use of meltwater rates provided by an ice sheet model applied as input to a mixed boundary condition enables to produce a more plausible flow field in the Eastern part of the domain, in comparison to previous modelling results (Jaquet et al. 2010). In addition, the integration of all potential taliks within the modelled domain provides a better characterisation of the likely groundwater
Groundwater flow modelling under ice sheet conditions in Greenland (phase II)
Energy Technology Data Exchange (ETDEWEB)
Jaquet, Olivier; Namar, Rabah; Siegel, Pascal [In2Earth Modelling Ltd, Lausanne (Switzerland); Jansson, Peter [Dept. of Physical Geography and Quaternary Geology, Stockholm Univ., Stockholm (Sweden)
2012-11-15
Within the framework of the GAP project, this second phase of geosphere modelling has enabled the development of an improved regional model that has led to a better representation of groundwater flow conditions likely to occur under ice sheet conditions. New data in relation to talik geometry and elevation, as well as to deformation zones were integrated in the geosphere model. In addition, more realistic hydraulic properties were considered for geosphere modelling; they were taken from the Laxemar site in Sweden. The geological medium with conductive deformation zones was modelled as a 3D continuum with stochastically hydraulic properties. Surface and basal glacial meltwater rates provided by a dynamic ice sheet model were assimilated into the groundwater flow model using mixed boundary conditions. The groundwater flow system is considered to be governed by infiltration of glacial meltwater in heterogeneous faulted crystalline rocks in the presence of permafrost and taliks. The characterisation of the permafrost-depth distribution was achieved using a coupled description of flow and heat transfer under steady state conditions. Using glaciological concepts and satellite data, an improved stochastic model was developed for the description at regional scale for the subglacial permafrost distribution in correlation with ice velocity and bed elevation data. Finally, the production of glacial meltwater by the ice sheet was traced for the determination of its depth and lateral extent. The major improvements are related to the type and handling of the subglacial boundary conditions. The use of meltwater rates provided by an ice sheet model applied as input to a mixed boundary condition enables to produce a more plausible flow field in the Eastern part of the domain, in comparison to previous modelling results (Jaquet et al. 2010). In addition, the integration of all potential taliks within the modelled domain provides a better characterisation of the likely groundwater
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
A scalable approach to modeling groundwater flow on massively parallel computers
International Nuclear Information System (INIS)
Ashby, S.F.; Falgout, R.D.; Tompson, A.F.B.
1995-12-01
We describe a fully scalable approach to the simulation of groundwater flow on a hierarchy of computing platforms, ranging from workstations to massively parallel computers. Specifically, we advocate the use of scalable conceptual models in which the subsurface model is defined independently of the computational grid on which the simulation takes place. We also describe a scalable multigrid algorithm for computing the groundwater flow velocities. We axe thus able to leverage both the engineer's time spent developing the conceptual model and the computing resources used in the numerical simulation. We have successfully employed this approach at the LLNL site, where we have run simulations ranging in size from just a few thousand spatial zones (on workstations) to more than eight million spatial zones (on the CRAY T3D)-all using the same conceptual model
Subglacial groundwater flow at Aespoe as governed by basal melting and ice tunnels
International Nuclear Information System (INIS)
Svensson, Urban
1999-02-01
A high resolution three dimensional numerical model of subglacial groundwater flow is described. The model uses conductivity data from the Aespoe region and is thus site specific. It is assumed that the groundwater flow is governed by the basal melting and ice tunnels; ice surface melting is not considered. Results are presented for the meltwater transport time (to the ice margin) and maximum penetration depth. Conditions at repository depth, i.e. about 500 metres, are also analysed. The general conclusion from the study is that the model presented gives plausible results, considering the basic conceptual assumptions made. It is however questioned if the hydraulics of the ice tunnels is well enough understood; this is a topic that is suggested for further studies
Groundwater flow analyses in Japan. 1. Case studies in Hokkaido and Northeast Japan
International Nuclear Information System (INIS)
Inaba, Hideo; Maekawa, Keisuke; Koide, Kaoru; Yanagizawa, Koichi
1995-01-01
An extensive study program has been carried out to estimate hydrogeological characteristics of deep underground in Japan. As a part of this program, groundwater flow analysis in Hokkaido and Northeast Japan were conducted. For the analyses of these area, hydrogeological models representing topography, geology, distribution of hydraulic conductivity were developed using available informations from open literature. By use of these models, steady state three-dimensional groundwater flow under a saturated/unsaturated condition was calculated by means of finite element method. The results are as follows: (1) Distribution of piezometric head corresponds with topography in the study area. (2) Piezometric head distribution is hydrostatic below E.L.-1000m in the study area. (3) Hydraulic gradient in the study area is less than 0.04 below E.L.-500m. (4) Difference of boundary conditions at the shore side of these models does not affect the results of the analyses. (author)
Katz, Brian G.; Lee, Terrie M.; Plummer, L. Niel; Busenberg, Eurybiades
1995-06-01
Leakage from sinkhole lakes significantly influences recharge to the Upper Floridan aquifer in poorly confined sediments in northern Florida. Environmental isotopes (oxygen 18, deuterium, and tritium), chlorofluorocarbons (CFCs: CFC-11, CCl3F; CFC-12, CCl2F2; and CFC-113, C2Cl3F3), and solute tracers were used to investigate groundwater flow patterns near Lake Barco, a seepage lake in a mantled karst setting in northern Florida. Stable isotope data indicated that the groundwater downgradient from the lake contained 11-67% lake water leakage, with a limit of detection of lake water in groundwater of 4.3%. The mixing fractions of lake water leakage, which passed through organic-rich sediments in the lake bottom, were directly proportional to the observed methane concentrations and increased with depth in the groundwater flow system. In aerobic groundwater upgradient from Lake Barco, CFC-modeled recharge dates ranged from 1987 near the water table to the mid 1970s for water collected at a depth of 30 m below the water table. CFC-modeled recharge dates (based on CFC-12) for anaerobic groundwater downgradient from the lake ranged from the late 1950s to the mid 1970s and were consistent with tritium data. CFC-modeled recharge dates based on CFC-11 indicated preferential microbial degradation in anoxic waters. Vertical hydraulic conductivities, calculated using CFC-12 modeled recharge dates and Darcy's law, were 0.17, 0.033, and 0.019 m/d for the surficial aquifer, intermediate confining unit, and lake sediments, respectively. These conductivities agreed closely with those used in the calibration of a three-dimensional groundwater flow model for transient and steady state flow conditions.
Directory of Open Access Journals (Sweden)
R. Barthel
2006-01-01
Full Text Available Model coupling requires a thorough conceptualisation of the coupling strategy, including an exact definition of the individual model domains, the "transboundary" processes and the exchange parameters. It is shown here that in the case of coupling groundwater flow and hydrological models – in particular on the regional scale – it is very important to find a common definition and scale-appropriate process description of groundwater recharge and baseflow (or "groundwater runoff/discharge" in order to achieve a meaningful representation of the processes that link the unsaturated and saturated zones and the river network. As such, integration by means of coupling established disciplinary models is problematic given that in such models, processes are defined from a purpose-oriented, disciplinary perspective and are therefore not necessarily consistent with definitions of the same process in the model concepts of other disciplines. This article contains a general introduction to the requirements and challenges of model coupling in Integrated Water Resources Management including a definition of the most relevant technical terms, a short description of the commonly used approach of model coupling and finally a detailed consideration of the role of groundwater recharge and baseflow in coupling groundwater models with hydrological models. The conclusions summarize the most relevant problems rather than giving practical solutions. This paper aims to point out that working on a large scale in an integrated context requires rethinking traditional disciplinary workflows and encouraging communication between the different disciplines involved. It is worth noting that the aspects discussed here are mainly viewed from a groundwater perspective, which reflects the author's background.
Directory of Open Access Journals (Sweden)
Elizabeth Peters
2018-01-01
Full Text Available Mount Shasta (4322 m is famous for its spring water. Water for municipal, domestic and industrial use is obtained from local springs and wells, fed by annual snow melt and sustained perennially by the groundwater flow system. We examined geochemical and isotopic tracers in samples from wells and springs on Mount Shasta, at the headwaters of the Sacramento River, in order to better understand the hydrologic system. The topographic relief in the study area imparts robust signatures of recharge elevation to both stable isotopes of the water molecule (δ18O and δD and to dissolved noble gases, offering tools to identify recharge areas and delineate groundwater flow paths. Recharge elevations determined using stable isotopes and noble gas recharge temperatures are in close agreement and indicate that most snowmelt infiltrates at elevations between 2000 m and 2900 m, which coincides with areas of thin soils and barren land cover. Large springs in Mt Shasta City discharge at an elevation more than 1600 m lower. High elevation springs (>2000 m yield very young water (<2 years while lower elevation wells (1000–1500 m produce water with a residence time ranging from 6 years to over 60 years, based on observed tritium activities. Upslope movement of the tree line in the identified recharge elevation range due to a warming climate is likely to decrease infiltration and recharge, which will decrease spring discharge and production at wells, albeit with a time lag dependent upon the length of groundwater flow paths.
Directory of Open Access Journals (Sweden)
Tada-nori Goto
2012-01-01
Full Text Available Self-potential (SP measurements were conducted at Mt. Tsukuba, Japan, which is a nonvolcanic mountain, to infer groundwater flow system in the mountain. Survey routes were set around the northern slope, and the reliability of observed SP anomaly was checked by using SP values along parallel survey routes; the error was almost within 10 mV. The FFT analysis of the spatial SP distribution allows us a separation of raw data into two components with shorter and longer wavelength. In the shorter (altitudinal wavelength than ∼200 meters, several positive SP peaks of more than 100 mV in magnitude are present, which indicate shallow perched water discharges along the slope. In the regional SP pattern of longer wavelength, there are two major perturbations from the general trend reflecting the topographic effect. By comparing the SP and hydrological data, the perturbation around the foothill is interpreted to be caused by heterogeneous infiltration at the ground surface. The perturbation around the summit is also interpreted to be caused by heterogeneous infiltration process, based on a simplified numerical modeling of SP. As a result, the SP pattern is well explained by groundwater flow and infiltration processes. Thus, SP data is thought to be very useful for understanding of groundwater flow system on a mountain scale.
Groundwater flow simulation of the Savannah River Site general separations area
Energy Technology Data Exchange (ETDEWEB)
Flach, G. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Bagwell, L. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Bennett, P. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)
2017-09-07
The most recent groundwater flow model of the General Separations Area, Savannah River Site, is referred to as the “GSA/PORFLOW” model. GSA/PORFLOW was developed in 2004 by porting an existing General Separations Area groundwater flow model from the FACT code to the PORFLOW code. The preceding “GSA/FACT” model was developed in 1997 using characterization and monitoring data through the mid-1990’s. Both models were manually calibrated to field data. Significantly more field data have been acquired since the 1990’s and model calibration using mathematical optimization software has become routine and recommended practice. The current task involved updating the GSA/PORFLOW model using selected field data current through at least 2015, and use of the PEST code to calibrate the model and quantify parameter uncertainty. This new GSA groundwater flow model is named “GSA2016” in reference to the year in which most development occurred. The GSA2016 model update is intended to address issues raised by the DOE Low-Level Waste (LLW) Disposal Facility Federal Review Group (LFRG) in a 2008 review of the E-Area Performance Assessment, and by the Nuclear Regulatory Commission in reviews of tank closure and Saltstone Disposal Facility Performance Assessments.
International Nuclear Information System (INIS)
Sakai, Ryutaro; Munakata, Masahiro; Ohoka, Masao; Kameya, Hiroshi
2009-11-01
In the safety assessment for a geological disposal of radioactive waste, it is important to develop a methodology for long-term estimation of regional groundwater flow from data acquisition to numerical analyses. In the uncertainties associated with estimation of regional groundwater flow, there are the one that concerns parameters and the one that concerns the hydrologeological evolution. The uncertainties of parameters include measurement errors and their heterogeneity. The authors discussed the uncertainties of hydraulic conductivity as a significant parameter for regional groundwater flow analysis. This study suggests that hydraulic conductivities of rock mass are controlled by rock characteristics such as fractures, porosity and test conditions such as hydraulic gradient, water quality, water temperature and that there exists variations more than ten times in hydraulic conductivity by difference due to test conditions such as hydraulic gradient or due to rock type variations such as rock fractures, porosity. In addition this study demonstrated that confining pressure change caused by uplift and subsidence and change of hydraulic gradient under the long-term evolution of hydrogeological environment could possibly produce variations more than ten times of magnitude in hydraulic conductivity. It was also shown that the effect of water quality change on hydraulic conductivity was not negligible and that the replacement of fresh water and saline water caused by sea level change could induce 0.6 times in current hydraulic conductivities in case of Horonobe site. (author)
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...
International Nuclear Information System (INIS)
Samper, J.; Carrera, J.; Bajos, C.; Astudillo, J.; Santiago, J.L.
1999-01-01
Hydrogeochemical activities have been a key factor for the verification and constraining of the groundwater flow model developed for the safety assessment of the FUA Uranium mill tailings restoration and the Cabril L/ILW disposal facility. The lesson learned in both sites will be applied to the ground water transport modelling in the current PA exercises (ENRESA 2000). The groundwater flow model in the Cabril site, represents a low permeability fractured media, and was performed using the TRANSIN code series developed by UPC-ENRESA. The hydrogeochemical data obtained from systematic yearly sampling and analysis campaigns were successfully applied to distinguish between local and regional flow and young and old groundwater. The salinity content, mainly the chlorine anion content, was the most critical hydrogeochemical data for constraining the groundwater flow model. (author)
Regional groundwater flow model for C, K. L. and P reactor areas, Savannah River Site, Aiken, SC
Energy Technology Data Exchange (ETDEWEB)
Flach, G.P.
2000-02-11
A regional groundwater flow model encompassing approximately 100 mi2 surrounding the C, K, L, and P reactor areas has been developed. The reactor flow model is designed to meet the planning objectives outlined in the General Groundwater Strategy for Reactor Area Projects by providing a common framework for analyzing groundwater flow, contaminant migration and remedial alternatives within the Reactor Projects team of the Environmental Restoration Department. The model provides a quantitative understanding of groundwater flow on a regional scale within the near surface aquifers and deeper semi-confined to confined aquifers. The model incorporates historical and current field characterization data up through Spring 1999. Model preprocessing is automated so that future updates and modifications can be performed quickly and efficiently. The CKLP regional reactor model can be used to guide characterization, perform scoping analyses of contaminant transport, and serve as a common base for subsequent finer-scale transport and remedial/feasibility models for each reactor area.
Regional groundwater flow model for C, K. L. and P reactor areas, Savannah River Site, Aiken, SC
International Nuclear Information System (INIS)
Flach, G.P.
2000-01-01
A regional groundwater flow model encompassing approximately 100 mi2 surrounding the C, K, L, and P reactor areas has been developed. The reactor flow model is designed to meet the planning objectives outlined in the General Groundwater Strategy for Reactor Area Projects by providing a common framework for analyzing groundwater flow, contaminant migration and remedial alternatives within the Reactor Projects team of the Environmental Restoration Department. The model provides a quantitative understanding of groundwater flow on a regional scale within the near surface aquifers and deeper semi-confined to confined aquifers. The model incorporates historical and current field characterization data up through Spring 1999. Model preprocessing is automated so that future updates and modifications can be performed quickly and efficiently. The CKLP regional reactor model can be used to guide characterization, perform scoping analyses of contaminant transport, and serve as a common base for subsequent finer-scale transport and remedial/feasibility models for each reactor area
International Nuclear Information System (INIS)
Ijiri, Yuji; Ono, Makoto; Sugihara, Yutaka; Shimo, Michito; Yamamoto, Hajime; Fumimura, Kenichi
2003-03-01
This study involves evaluation of uncertainty in hydrogeological modeling and groundwater flow analysis. Three-dimensional groundwater flow in Shobasama site in Tono was analyzed using two continuum models and one discontinuous model. The domain of this study covered area of four kilometers in east-west direction and six kilometers in north-south direction. Moreover, for the purpose of evaluating how uncertainties included in modeling of hydrogeological structure and results of groundwater simulation decreased with progress of investigation research, updating and calibration of the models about several modeling techniques of hydrogeological structure and groundwater flow analysis techniques were carried out, based on the information and knowledge which were newly acquired. The acquired knowledge is as follows. As a result of setting parameters and structures in renewal of the models following to the circumstances by last year, there is no big difference to handling between modeling methods. The model calibration is performed by the method of matching numerical simulation with observation, about the pressure response caused by opening and closing of a packer in MIU-2 borehole. Each analysis technique attains reducing of residual sum of squares of observations and results of numerical simulation by adjusting hydrogeological parameters. However, each model adjusts different parameters as water conductivity, effective porosity, specific storage, and anisotropy. When calibrating models, sometimes it is impossible to explain the phenomena only by adjusting parameters. In such case, another investigation may be required to clarify details of hydrogeological structure more. As a result of comparing research from beginning to this year, the following conclusions are obtained about investigation. (1) The transient hydraulic data are effective means in reducing the uncertainty of hydrogeological structure. (2) Effective porosity for calculating pore water velocity of
International Nuclear Information System (INIS)
Bottoni, M.; Sengpiel, W.
1992-01-01
Starting from the rigorous formulation of the conservation equations for mass, momentum and enthalpy, derived for a two-phase flow by volume averaging microscopic balance equations over Eulerian control cells, the article discusses the formulation of the terms describing exchanges between the phases. Two flow regimes are taken into consideration, bubbly flow, applicable for small or medium void fractions, and annular flow, for large void fractions. When lack of knowledge of volume-averaged physical quantities make the rigorously formulated terms useless for computational purposes, modelling of these terms is discussed. 3 figs., 15 refs
Numerical simulation of the groundwater-flow system of the Kitsap Peninsula, west-central Washington
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
Weber, Lisa C.; Wiley, Michael J.; Wilcox, Douglas A.
2016-01-01
The use of diurnal water-table fluctuation methods to calculate evapotranspiration (ET) and groundwater flow is of increasing interest in ecohydrological studies. Most studies of this type, however, have been located in riparian wetlands of semi-arid regions where groundwater levels are consistently below topographic surface elevations and precipitation events are infrequent. Current methodologies preclude application to a wider variety of wetland systems. In this study, we extended a method for estimating sub-daily ET and groundwater flow rates from water-level fluctuations to fit highly dynamic, non-riparian wetland scenarios. Modifications included (1) varying the specific yield to account for periodic flooded conditions and (2) relating empirically derived ET to estimated potential ET for days when precipitation events masked the diurnal signal. To demonstrate the utility of this method, we estimated ET and groundwater fluxes over two growing seasons (2006–2007) in 15 wetlands within a ridge-and-swale wetland complex of the Laurentian Great Lakes under flooded and non-flooded conditions. Mean daily ET rates for the sites ranged from 4.0 mm d−1 to 6.6 mm d−1. Shallow groundwater discharge rates resulting from evaporative demand ranged from 2.5 mm d−1 to 4.3 mm d−1. This study helps to expand our understanding of the evapotranspirative demand of plants under various hydrologic and climate conditions. Published 2013. This article is a U.S. Government work and is in the public domain in the USA.
Palaeosol control on groundwater flow and pollutant distribution: the example of arsenic.
McArthur, John M; Nath, Bibhash; Banerjee, Dhiraj M; Purohit, R; Grassineau, N
2011-02-15
The consumption of groundwater polluted by arsenic (As) has a severe and adverse effect on human health, particularly where, as happens in parts of SE Asia, groundwater is supplied largely from fluvial/deltaic aquifers. The lateral distribution of the As-pollution in such aquifers is heterogeneous. The cause of the heterogeneity is obscure. The location and severity of the As-pollution is therefore difficult to predict, despite the importance of such predictions to the protection of consumer health, aquifer remediation, and aquifer development. To explain the heterogeneity, we mapped As-pollution in groundwater using 659 wells across 102 km(2) of West Bengal, and logged 43 boreholes, to reveal that the distribution of As-pollution is governed by subsurface sedimentology. Across 47 km(2) of contiguous palaeo-interfluve, we found that the shallow aquifer (channels, the palaeosol is absent, so invasion of the aquifer by As and dissolved organic matter can occur, so palaeo-channel groundwater is mostly polluted by As (>50 μg/L). The role of palaeosols and, in particular, the LGMP, has been overlooked as a control on groundwater flow and pollutant movement in deltaic and coastal aquifers worldwide. Models of pollutant infiltration in such environments must include the appreciation that, where the LGMP (or other palaeosols) are present, recharge moves downward in palaeo-channel regions that are separated by palaeo-interfluvial regions where vertical recharge to underlying aquifers cannot occur and where horizontal flow occurs above the LGMP and any aquifer it caps.
First status report on regional and local ground-water flow modeling for Richton Dome, Mississippi
International Nuclear Information System (INIS)
Andrews, R.W.; Metcalfe, D.E.
1984-03-01
Regional and local ground-water flow within the principal hydrogeologic units in the vicinity of Richton Dome is evaluated by developing conceptual models of the flow regime within these units at three different scales and testing these models using a three-dimensional, finite-difference flow code. Semiquantitative sensitivity analysis is conducted to define the system response to changes in the conceptual model, particularly the hydrologic properties. The effects of salinity on the flow field are evaluated at the refined and local scales. Adjoint sensitivity analysis is applied to the conceptualized flow regime in the Wilcox aquifer. All steps leading to the final results and conclusions are incorporated in this report. The available data utilized in this study is summarized. The specific conceptual models, defining the areal and vertical averaging of lithologic units, aquifer properties, fluid properties, and hydrologic boundary conditions, are described in detail. The results are delineated by the simulated potentiometric surfaces and tables summarizing areal and vertical boundary fluxes, Darcy velocities at specific points, and ground-water travel paths. These results are presented at regional, refined, and local (near-dome) scales. The reported work is the first stage of an ongoing evaluation of the Richton Dome as a potential repository for high-level radioactive wastes. The results and conclusions should thus be considered preliminary and subject to modification with the collection of additional data. However, this report does provide a useful basis for describing the sensitivity and, to a lesser extent, the uncertainty of the present conceptualization of ground-water flow in the vicinity of Richton Dome. 25 references, 69 figures, 15 tables
16 reference population equations using peak expiratory flow meters
African Journals Online (AJOL)
DR. AMINU
equations in current use are based on linear statistical models which are subject to change and they did not ... assess risks of surgery and to assist in evaluations performed ... identify and quantify pulmonary involvement incases of asthma.
International Nuclear Information System (INIS)
Miller, D.R.; Paige, R.W.
1988-07-01
The HYDROCOIN project is an international collaborative venture for comparing groundwater flow models and modelling strategies. Level 2 of this project concerns the validation of models in order to test their ability adequately to represent reality. This report describes calculations for the regional groundwater flow in the Piceance Basin of northwestern Colorado. This region constitutes one of the few areas where low permeability rocks, similar to those likely to be used for repository sites, have been investigated by hydrogeologists. (author)
Nelson, Kirk E.; Ginn, Timothy R.
2011-05-01
A new equation for the collector efficiency (η) of the colloid filtration theory (CFT) is developed via nonlinear regression on the numerical data generated by a large number of Lagrangian simulations conducted in Happel's sphere-in-cell porous media model over a wide range of environmentally relevant conditions. The new equation expands the range of CFT's applicability in the natural subsurface primarily by accommodating departures from power law dependence of η on the Peclet and gravity numbers, a necessary but as of yet unavailable feature for applying CFT to large-scale field transport (e.g., of nanoparticles, radionuclides, or genetically modified organisms) under low groundwater velocity conditions. The new equation also departs from prior equations for colloids in the nanoparticle size range at all fluid velocities. These departures are particularly relevant to subsurface colloid and colloid-facilitated transport where low permeabilities and/or hydraulic gradients lead to low groundwater velocities and/or to nanoparticle fate and transport in porous media in general. We also note the importance of consistency in the conceptualization of particle flux through the single collector model on which most η equations are based for the purpose of attaining a mechanistic understanding of the transport and attachment steps of deposition. A lack of sufficient data for small particles and low velocities warrants further experiments to draw more definitive and comprehensive conclusions regarding the most significant discrepancies between the available equations.
Directory of Open Access Journals (Sweden)
T. Vogt
2012-02-01
Full Text Available River-water infiltration is of high relevance for hyporheic and riparian groundwater ecology as well as for drinking water supply by river-bank filtration. Heat has become a popular natural tracer to estimate exchange rates between rivers and groundwater. However, quantifying flow patterns and velocities is impeded by spatial and temporal variations of exchange fluxes, insufficient sensors spacing during field investigations, or simplifying assumptions for analysis or modeling such as uniform flow. The objective of this study is to investigate lateral shallow groundwater flow upon river-water infiltration at the shoreline of the riverbed and in the adjacent riparian zone of the River Thur in northeast Switzerland. Here we have applied distributed temperature sensing (DTS along optical fibers wrapped around tubes to measure high-resolution vertical temperature profiles of the unsaturated zone and shallow riparian groundwater. Diurnal temperature oscillations were tracked in the subsurface and analyzed by means of dynamic harmonic regression to extract amplitudes and phase angles. Subsequent calculations of amplitude attenuation and time shift relative to the river signal show in detail vertical and temporal variations of heat transport in shallow riparian groundwater. In addition, we apply a numerical two-dimensional heat transport model for the unsaturated zone and shallow groundwater to obtain a better understanding of the observed heat transport processes in shallow riparian groundwater and to estimate the groundwater flow velocity. Our results show that the observed riparian groundwater temperature distribution cannot be described by uniform flow, but rather by horizontal groundwater flow velocities varying over depth. In addition, heat transfer of diurnal temperature oscillations from the losing river through shallow groundwater is influenced by thermal exchange with the unsaturated zone. Neglecting the influence of the unsaturated zone
Bursey, G.; Seok, E.; Gale, J. E.
2017-12-01
Flow to underground mines and open pits takes place through an interconnected network of regular joints/fractures and intermediate to large scale structural features such as faults and fracture zones. Large scale features can serve either as high permeability pathways or as barriers to flow, depending on the internal characteristics of the structure. Predicting long term water quality in barrier-well systems and long-term mine water inflows over a mine life, as a mine expands, requires the use of a 3D numerical flow and transport code. The code is used to integrate the physical geometry of the fractured-rock mass with porosity, permeability, hydraulic heads, storativity and recharge data and construct a model of the flow system. Once that model has been calibrated using hydraulic head and permeability/inflow data, aqueous geochemical and isotopic data provide useful tools for validating flow-system properties, when one is able to recognize and account for the non-ideal or imperfect aspects of the sampling methods used in different mining environments. If groundwater samples are collected from discrete depths within open boreholes, water in those boreholes have the opportunity to move up or down in response to the forces that drive groundwater flow, whether they be hydraulic gradients, gas pressures, or density differences associated with variations in salinity. The use of Br/Cl ratios, for example, can be used to determine if there is active flow into, or out of, the boreholes through open discontinuities in the rock mass (i.e., short-circuiting). Natural groundwater quality can also be affected to varying degrees by mixing with drilling fluids. The combined use of inorganic chemistry and stable isotopes can be used effectively to identify dilution signals and map the dilution patterns through a range of fresh, brackish and saline water types. The stable isotopes of oxygen and hydrogen are nearly ideal natural tracers of water, but situations occur when deep
Modelling of groundwater flow and solute transport in Olkiluoto. Update 2008
International Nuclear Information System (INIS)
Loefman, J.; Pitkaenen, P.; Meszaros, F.; Keto, V.; Ahokas, H.
2009-10-01
Posiva Oy is preparing for the final disposal of spent nuclear fuel in the crystalline bedrock in Finland. Olkiluoto in Eurajoki has been selected as the primary site for the repository, subject to further detailed characterisation which is currently focused on the construction of an underground rock characterisation and research facility (the ONKALO). An essential part of the site investigation programme is analysis of the deep groundwater flow by means of numerical flow modelling. This study is the latest update concerning the site-scale flow modelling and is based on all the hydrogeological data gathered from field investigations by the end of 2007. The work is divided into two separate modelling tasks: 1) characterization of the baseline groundwater flow conditions before excavation of the ONKALO, and 2) a prediction/outcome (P/O) study of the potential hydrogeological disturbances due to the ONKALO. The flow model was calibrated by using all the available data that was appropriate for the applied, deterministic, equivalent porous medium (EPM) / dual-porosity (DP) approach. In the baseline modelling, calibration of the flow model focused on improving the agreement between the calculated results and the undisturbed observations. The calibration resulted in a satisfactory agreement with the measured pumping test responses, a very good overall agreement with the observed pressures in the deep drill holes and a fairly good agreement with the observed salinity. Some discrepancies still remained in a few single drill hole sections, because the fresh water infiltration in the model tends to dilute the groundwater too much at shallow depths. In the P/O calculations the flow model was further calibrated by using the monitoring data on the ONKALO disturbances. Having significantly more information on the inflows to the tunnel (compared with the previous study) allowed better calibration of the model, which allowed it to capture very well the observed inflow, the
Kincaid, T. R.; Meyer, B. A.
2009-12-01
In groundwater flow modeling, aquifer permeability is typically defined through model calibration. Since the pattern and size of conduits are part of a karstic permeability framework, those parameters should be constrainable through the same process given a sufficient density of measured conditions. H2H Associates has completed a dual-permeability steady-state model of groundwater flow through the western Santa Fe River Basin, Florida from which a 380.9 km network of saturated conduits was delineated through model calibration to heads and spring discharges. Two calibration datasets were compiled describing average high-water and average low-water conditions based on heads at 145 wells and discharge from 18 springs for the high-water scenario and heads at 188 wells and discharge from 9 springs for the low-water scenario. An initial conduit network was defined by assigning paths along mapped conduits and inferring paths along potentiometric troughs between springs and swallets that had been connected by groundwater tracing. These initial conduit assignments accounted for only 13.75 and 34.1 km of the final conduit network respectively. The model was setup using FEFLOW™ where conduits were described as discrete features embedded in a porous matrix. Flow in the conduits was described by the Manning-Strickler equation where variables for conduit area and roughness were used to adjust the volume and velocity of spring flows. Matrix flow was described by Darcy’s law where hydraulic conductivity variations were limited to three geologically defined internally homogeneous zones that ranged from ~2E-6 m/s to ~4E-3 m/s. Recharge for both the high-water and low-water periods was determined through a water budget analysis where variations were restricted to nine zones defined by land-use. All remaining variations in observed head were then assumed to be due to conduits. The model was iteratively calibrated to the high-water and low-water datasets wherein the location, size
Energy Technology Data Exchange (ETDEWEB)
Jaunat, J.; Huneau, F.; Dupuy, A.; Franceschi, M.; Le Coustumer, P. [Universite de Bordeaux, Institut EGID, EA Georessources et Environnement, Pessac (France); Celle-Jeanton, H. [Universite de Clermont-Ferrand, LMV UMR 6524, Clermont-Ferrand (France)
2013-07-15
Stable isotopes of the water molecule and tritium in conjunction with geochemistry have been used to understand the groundwater flow pattern and origin within the gneissic aquifer of the Ursuya Mount. This aquifer constitutes one of the main water supplies of the Northern Basque Country and improved knowledge about the water recharge, origin, quality and residence time is of strategic importance for a sustainable development of the resource. 16 springs, 4 boreholes and total rainfall have been sampled monthly since summer 2009. Preliminary results indicate complex and contrasted groundwater flows within the aquifer. Shallow groundwater restricted to the upper weathered horizons is characterized by a strong influence of anthropogenic inputs. At depth, groundwater mainly circulates along the major structural discontinuities of the gneiss in semi-confined conditions. These levels, providing the most promising resource for the water supply, show increased water mineralization caused by a longer residence time of groundwater and hence indicate a slower dynamic of the system. (author)
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.
Regional ground-water flow modeling for the Paradox Basin, Utah: Second status report
International Nuclear Information System (INIS)
1986-09-01
Regional ground-water flow within the principal geohydrologic units of the Paradox Basin is evaluated by developing a conceptual model of the flow regime between the shallow aquifers, the Paradox salt and the deep-basin brine aquifers. This model is tested using a three-dimensional, finite-difference flow code. Sensitivity analyses (a limited parametric study) are conducted to define the system responses to changes in the conceptual model. The conceptual model is described in terms of its areal and vertical discretization, aquifer properties, fluid properties, and hydrologic boundary conditions. The simulated results are described with potentiometric surfaces, tables summarizing the areal and vertical volumetric flows through the principal units, and Darcy velocities at specified points. The reported work is the second stage of an ongoing evaluation of the Gisbon Dome area within the Paradox Basin as a potential repository for high-level radioactive wastes. The results and conclusions should thus be considered preliminary and subject to modification with the collection of additional data. However, the report does provide a useful basis for describing the sensitivity of the present conceptualization of ground-water flow to the hydrologic parameters and, to a lesser extent, the uncertainties of the present conceptualization. 20 refs., 17 figs., 9 tabs
Bedrock Hydrogeology - Groundwater flow modelling. Site investigation SFR
Energy Technology Data Exchange (ETDEWEB)
Oehman, Johan [Geosigma AB, Uppsala (Sweden); Follin, Sven [SF GeoLogic AB, Taeby (Sweden); Oden, Magnus [SKB, Stockholm (Sweden)
2013-05-15
The hydrogeological model developed for the SFR extension project (PSU) consists of 40 geologically modelled deformation zones (DZ) and 8 sub-horizontal structural-hydraulic features, called SBAstructures, not defined in the geological model. However, some of the SBA-structures coincide with what is defined as unresolved possible deformation zones (Unresolved PDZ) in the geological modelling. In addition, the hydrogeological model consists of a stochastic discrete fracture network (DFN) model intended for the less fractured rock mass volumes (fracture domains) between the zones and the SBA-structures, and a stochastic fracture model intended to handle remaining Unresolved PDZs in the geological modelling not modelled as SBA-structures in the hydrogeological modelling. The four structural components of the bedrock in the hydrogeological model, i.e. DZ, SBA, Unresolved PDZ and DFN, are assigned hydraulic properties in the hydrogeological model based on the transmissivities interpreted from single-hole hydraulic tests. The main objective of the present work is to present the characteristics of the hydrogeological model with regard to the needs of the forthcoming safety assessment SR-PSU. In concrete words, simulated data are compared with measured data, i.e. hydraulic heads in boreholes and tunnel inflow to the existing repository (SFR). The calculations suggest that the available data for flow model calibration cannot be used to motivate a substantial adjustment of the initial hydraulic parameterisation (assignment of hydraulic properties) of the hydrogeological model. It is suggested that uncertainties in the hydrogeological model are studied in the safety assessment SR-PSU by means of a large number of calculation cases. These should address hydraulic heterogeneity of deterministic structures (DZ and SBA) and realisations of stochastic fractures/fracture networks (Unresolved PDZ and DFN) within the entire SFR Regional model domain.
Bedrock Hydrogeology-Groundwater flow modelling. Site investigation SFR
International Nuclear Information System (INIS)
Oehman, Johan; Follin, Sven; Oden, Magnus
2013-05-01
The hydrogeological model developed for the SFR extension project (PSU) consists of 40 geologically modelled deformation zones (DZ) and 8 sub-horizontal structural-hydraulic features, called SBAstructures, not defined in the geological model. However, some of the SBA-structures coincide with what is defined as unresolved possible deformation zones (Unresolved PDZ) in the geological modelling. In addition, the hydrogeological model consists of a stochastic discrete fracture network (DFN) model intended for the less fractured rock mass volumes (fracture domains) between the zones and the SBA-structures, and a stochastic fracture model intended to handle remaining Unresolved PDZs in the geological modelling not modelled as SBA-structures in the hydrogeological modelling. The four structural components of the bedrock in the hydrogeological model, i.e. DZ, SBA, Unresolved PDZ and DFN, are assigned hydraulic properties in the hydrogeological model based on the transmissivities interpreted from single-hole hydraulic tests. The main objective of the present work is to present the characteristics of the hydrogeological model with regard to the needs of the forthcoming safety assessment SR-PSU. In concrete words, simulated data are compared with measured data, i.e. hydraulic heads in boreholes and tunnel inflow to the existing repository (SFR). The calculations suggest that the available data for flow model calibration cannot be used to motivate a substantial adjustment of the initial hydraulic parameterisation (assignment of hydraulic properties) of the hydrogeological model. It is suggested that uncertainties in the hydrogeological model are studied in the safety assessment SR-PSU by means of a large number of calculation cases. These should address hydraulic heterogeneity of deterministic structures (DZ and SBA) and realisations of stochastic fractures/fracture networks (Unresolved PDZ and DFN) within the entire SFR Regional model domain
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)
International Nuclear Information System (INIS)
Anezaki, S.
1998-03-01
Sea/fresh-water boundary caused by density and concentration balance of sea-water and fresh-water is an important item for groundwater flow evaluation in deep underground near the coast. Also, in order to evaluate groundwater quality, it is important to understand the characteristics of sea/fresh-water boundary, for example boundary shape, salt distribution. In order to establish the evaluation and analytical methods for groundwater flow with considering sea/fresh-water boundary, we investigated the following items in this study. (1) Literature survey and data collection. (2) Investigation of analytical methods. (3) Planning of further study. (author). 78 refs
Explicit flow equations and recursion operator of the ncKP hierarchy
International Nuclear Information System (INIS)
He, Jingsong; Wang, Lihong; Tu, Junyi; Li, Xiaodong
2011-01-01
The explicit expression of the flow equations of the noncommutative Kadomtsev–Petviashvili (ncKP) hierarchy is derived. Compared with the flow equations of the KP hierarchy, our result shows that the additional terms in the flow equations of the ncKP hierarchy indeed consist of commutators of dynamical coordinates {u i }. The recursion operator for the flow equations under n-reduction is presented. Further, under 2-reduction, we calculate a nonlocal recursion operator Φ(2) of the noncommutative Korteweg–de Vries(ncKdV) hierarchy, which generates a hierarchy of local, higher-order flows. Thus we solve the open problem proposed by Olver and Sokolov (1998 Commun. Math. Phys. 193 245–68)
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.
Jena, S.
2015-12-01
The overexploitation of groundwater resulted in abandoning many shallow tube wells in the river Basin in Eastern India. For the sustainability of groundwater resources, basin-scale modelling of groundwater flow is essential for the efficient planning and management of the water resources. The main intent of this study is to develope a 3-D groundwater flow model of the study basin using the Visual MODFLOW package and successfully calibrate and validate it using 17 years of observed data. The sensitivity analysis was carried out to quantify the susceptibility of aquifer system to the river bank seepage, recharge from rainfall and agriculture practices, horizontal and vertical hydraulic conductivities, and specific yield. To quantify the impact of parameter uncertainties, Sequential Uncertainty Fitting Algorithm (SUFI-2) and Markov chain Monte Carlo (MCMC) techniques were implemented. Results from the two techniques were compared and the advantages and disadvantages were analysed. Nash-Sutcliffe coefficient (NSE) and coefficient of determination (R2) were adopted as two criteria during calibration and validation of the developed model. NSE and R2 values of groundwater flow model for calibration and validation periods were in acceptable range. Also, the MCMC technique was able to provide more reasonable results than SUFI-2. The calibrated and validated model will be useful to identify the aquifer properties, analyse the groundwater flow dynamics and the change in groundwater levels in future forecasts.
Kwon, Young-Sam; Lin, Ying-Chieh; Su, Cheng-Fang
2018-04-01
In this paper, we consider the compressible models of magnetohydrodynamic flows giving rise to a variety of mathematical problems in many areas. We derive a rigorous quasi-geostrophic equation governed by magnetic field from the rotational compressible magnetohydrodynamic flows with the well-prepared initial data. It is a first derivation of quasi-geostrophic equation governed by the magnetic field, and the tool is based on the relative entropy method. This paper covers two results: the existence of the unique local strong solution of quasi-geostrophic equation with the good regularity and the derivation of a quasi-geostrophic equation.
International Nuclear Information System (INIS)
D'Agnese, F.A.; Faunt, C.C.; Turner, A.K.; Hill, M.C.
1997-01-01
Yucca Mountain is being studied as a potential site for a high-level radioactive waste repository. In cooperation with the U.S. Department of Energy, the U.S. Geological Survey is evaluating the geologic and hydrologic characteristics of the ground-water system. The study area covers approximately 100,000 square kilometers between lat 35 degrees N., long 115 degrees W and lat 38 degrees N., long 118 degrees W and encompasses the Death Valley regional ground-water flow system. Hydrology in the region is a result of both the and climatic conditions and the complex described as dominated by interbasinal flow and may be conceptualized as having two main components: a series of relatively shallow and localized flow paths that are superimposed on deeper regional flow paths. A significant component of the regional ground-water flow is through a thick Paleozoic carbonate rock sequence. Throughout the regional flow system, ground-water flow is probably controlled by extensive and prevalent structural features that result from regional faulting and fracturing. Hydrogeologic investigations over a large and hydrogeologically complex area impose severe demands on data management. This study utilized geographic information systems and geoscientific information systems to develop, store, manipulate, and analyze regional hydrogeologic data sets describing various components of the ground-water flow system
First status report on regional groundwater flow modeling for the Palo Duro Basin, Texas
International Nuclear Information System (INIS)
Andrews, R.W.
1984-12-01
Regional groundwater flow within the principal hydrogeological units of the Palo Duro Basin is evaluated by developing a conceptual model of the flow regime in the shallow aquifers and the deep-basin brine aquifers and testing these models using a three-dimensional, finite-difference flow code. Semiquantitative sensitivity analysis (a limited parametric study) is conducted to define the system response to changes in hydrologic properties or boundary conditions. Adjoint sensitivity analysis is applied to the conceptualized flow regime in the Wolfcamp carbonate aquifer. All steps leading to the final results and conclusions are incorporated in this report. The available data utilized in this study are summarized. The specific conceptual models, defining the areal and vertical averaging of lithologic units, aquifer properties, fluid properties, and hydrologic boundary conditions, are described in detail. The results are delineated by the simulated potentiometric surfaces and tables summarizing areal and vertical boundary fluxes, Darcy velocities at specific points, and groundwater travel paths. Results from the adjoint sensitivity analysis included importance functions and sensitivity coefficients, using heads or the average Darcy velocities as the performance measures. The reported work is the first stage of an ongoing evaluation of two areas within the Palo Duro Basin as potantial repositories for high-level radioactive wastes. The results and conclusions should thus be considered preliminary and subject to modification with the collection of additional data. However, this report does provide a useful basis for describing the sensitivity and, to a lesser extent, the uncertainty of the present conceptualization of groundwater flow within the Palo Duro Basin
Arnold, B. W.; Gardner, P.
2013-12-01
Calibration of groundwater flow models for the purpose of evaluating flow and aquifer heterogeneity typically uses observations of hydraulic head in wells and appropriate boundary conditions. Environmental tracers have a wide variety of decay rates and input signals in recharge, resulting in a potentially broad source of additional information to constrain flow rates and heterogeneity. A numerical study was conducted to evaluate the reduction in uncertainty during model calibration using observations of various environmental tracers and combinations of tracers. A synthetic data set was constructed by simulating steady groundwater flow and transient tracer transport in a high-resolution, 2-D aquifer with heterogeneous permeability and porosity using the PFLOTRAN software code. Data on pressure and tracer concentration were extracted at well locations and then used as observations for automated calibration of a flow and transport model using the pilot point method and the PEST code. Optimization runs were performed to estimate parameter values of permeability at 30 pilot points in the model domain for cases using 42 observations of: 1) pressure, 2) pressure and CFC11 concentrations, 3) pressure and Ar-39 concentrations, and 4) pressure, CFC11, Ar-39, tritium, and He-3 concentrations. Results show significantly lower uncertainty, as indicated by the 95% linear confidence intervals, in permeability values at the pilot points for cases including observations of environmental tracer concentrations. The average linear uncertainty range for permeability at the pilot points using pressure observations alone is 4.6 orders of magnitude, using pressure and CFC11 concentrations is 1.6 orders of magnitude, using pressure and Ar-39 concentrations is 0.9 order of magnitude, and using pressure, CFC11, Ar-39, tritium, and He-3 concentrations is 1.0 order of magnitude. Data on Ar-39 concentrations result in the greatest parameter uncertainty reduction because its half-life of 269
Cubic Plus Association Equation of State for Flow Assurance Projects
DEFF Research Database (Denmark)
dos Santos, Leticia Cotia; Abunahman, Samir Silva; Tavares, Frederico Wanderley
2015-01-01
Thermodynamic hydrate inhibitors such as methanol, ethanol, (mono) ethylene glycol (MEG), and triethylene glycol (TEG) are widely used in the oil and gas industry. On modeling these compounds, we show here how the CPA equation of state was implemented in an in-house process simulator as an in......-built model: To validate the implementation, we show calulations for binary systems containing hydrate inhibitors and water or hydrocarbons using the Cubic Plus Association (CPA) and Soave-Redlich-Kwong (SRK) equation of states, also comparing against experimental data. For streams containing natural gas...
O'connell, Y.; Daly, E.; Duffy, G.; Henry, T.
2012-12-01
Large volumes of groundwater, containing nutrients and contaminants enter the coastal waters of southern Galway Bay on the west coast of Ireland through submarine groundwater discharge (SGD). The SGD occurs through karstified Carboniferous limestone in a major karst region comprising the Burren and Gort Lowlands. The Carboniferous limestones have experienced extensive dissolution resulting in the development of an underground network of conduits and fissures that define a trimodal groundwater flow pattern across the region. Groundwater discharge to the sea in this area is exclusively intertidal and submarine. Storage in the karst is limited and typical winter rainfall conditions result in the karst system becoming saturated. Temporary lakes (turloughs) form in lowlying areas and act as large reservoirs which provide storage to enable the transmission of the large volumes of water in the system to the sea. Between 2010 and 2012, terrestrial and shallow marine geophysical surveying has been undertaken to investigate preferential groundwater flow-paths and SGD locations in order to quantify the groundwater-seawater interactions in this coastal karst system. A report into the groundwater system of this karst region following a major flood event proposed a conceptual conduit model defined by extensive water tracing, water level monitoring, hydrochemical sampling, geological mapping and drilling. Limited information about the dimensions of the conduits was known. Electrical resistivity tomography (ERT) profiling to depths of 100m below ground level, with multiple array configurations, has been carried out to investigate the modes of groundwater flow in to and out of both temporary and permanent freshwater lakes in the system. Towed dipole-dipole profiles have been recorded to investigate conduits beneath a permanent lake exhibiting a tidal influence despite its location 5.5 km from the seashore. The ERT data indicates significant variations in subsurface resistivities
International Nuclear Information System (INIS)
McCarthy, J.M.; Arnett, R.C.; Neupauer, R.M.
1995-03-01
This report documents a study conducted to develop a regional groundwater flow model for the Eastern Snake River Plain Aquifer in the area of the Idaho National Engineering Laboratory. The model was developed to support Waste Area Group 10, Operable Unit 10-04 groundwater flow and transport studies. The products of this study are this report and a set of computational tools designed to numerically model the regional groundwater flow in the Eastern Snake River Plain aquifer. The objective of developing the current model was to create a tool for defining the regional groundwater flow at the INEL. The model was developed to (a) support future transport modeling for WAG 10-04 by providing the regional groundwater flow information needed for the WAG 10-04 risk assessment, (b) define the regional groundwater flow setting for modeling groundwater contaminant transport at the scale of the individual WAGs, (c) provide a tool for improving the understanding of the groundwater flow system below the INEL, and (d) consolidate the existing regional groundwater modeling information into one usable model. The current model is appropriate for defining the regional flow setting for flow submodels as well as hypothesis testing to better understand the regional groundwater flow in the area of the INEL. The scale of the submodels must be chosen based on accuracy required for the study
Haque, S. E.; Johannesson, K. H.
2006-05-01
Arsenic (As) concentrations and speciation were determined in groundwaters along a flow-path in the Upper Floridan aquifer (UFA) to investigate the biogeochemical “evolution“ of As in this relatively pristine aquifer. Dissolved inorganic As species were separated in the field using anion-exchange chromatography and subsequently analyzed by inductively coupled plasma mass spectrometry. Total As concentrations are higher in the recharge area groundwaters compared to down-gradient portions of UFA. Redox conditions vary from relatively oxic to anoxic along the flow-path. Mobilization of As species in UFA groundwaters is influenced by ferric iron reduction and subsequent dissolution, sulfate reduction, and probable pyrite precipitation that are inferred from the data to occur along distinct regions of the flow-path. In general, the distribution of As species are consistent with equilibrium thermodynamics, such that arsenate dominates in more oxidizing waters near the recharge area, and arsenite predominates in the progressively reducing groundwaters beyond the recharge area.
International Nuclear Information System (INIS)
Morgenstern, U.; van der Raaij, R.; Baalousha, H.
2012-01-01
The Ruataniwha Basin is situated in the upper Tukituki catchment, approximately 70 km south west of Napier City. The boundaries of the Ruataniwha Basin are the foothills of the Ruahine Range in the west, Turiri Range and Raukawa Range in the east and rolling hills in the north. The Ruataniwha Plains groundwater system is a multi-layered aquifer system that has a complex hydrogeological setting, as the plains evolved in response to sea-level changes, tectonic activity, and geomorphic processes. Aquifers in the basin occur in gravel, sandstone, pumice and limestone strata within a basin structure. In this study, groundwater samples have been collected for hydrochemistry, dissolved gases, and age tracer analysis. Tracer results were interpreted in terms of groundwater recharge source and rate, groundwater age, changes in groundwater source, and the homogeneity of the aquifers. This helps with conceptual understanding of Ruataniwha Basin groundwater flow patterns, and provides data for calibration of a numerical surface-groundwater flow model. Most water samples across the Ruataniwha Basin contain old water, with a mean residence time (MRT) > 25 years. The old age of most of the waters indicates that these groundwaters are not directly linked to surface water. In the south eastern part of the basin, all groundwater samples are old (>100 years), indicating slow movement of groundwater and slow recharge, consistent with the geology of the area. In the south eastern part of the basin the geologic units have low permeability. The age depth relationship is biased by upwelling groundwater and reflects the closed nature of the basin. The average vertical flow velocity indicates a recharge rate of 0.19 m/y. Four wells in the vicinity of the lower Waipawa River show excellent age-depth relationships, indicating absence of disturbance by groundwater upwelling. The recharge rate there of 0.42 m/y is substantially higher than in the other parts of the basin, indicating river
Revised model of regional groundwater flow of the Whiteshell Research Area: Summary
International Nuclear Information System (INIS)
Ophori, D.U.; Stevenson, D.R.; Gascoyne, M.; Brown, A.; Davison, C.C.; Chan, T.; Stanchell, F.W.
1995-10-01
Regional groundwater flow of the Whiteshell Research Area (WRA) is simulated in order to evaluate alternative locations for a hypothetical nuclear fuel waste disposal vault that maximizes retention of vault contaminants in the geosphere, and to define boundary conditions for a smaller local model around the vault. A revised conceptual model of the hydrogeologic conditions was constructed using all the information obtained from field investigations at the WRA between 1977 and 1994. All the simulations were performed using AECL's three-dimensional finite-element code, MOTIF. Average values of hydraulic parameters obtained from the field data were used for a base-case simulation, in which freshwater was assumed to occur in the entire flow region. The simulated average groundwater recharge rate for this base case did not compare favourably with the recharge rate that was estimated from the field data. Model calibration was ultimately achieved by modifying the hydraulic parameters and total dissolved solids (TDS) distribution of the fluid in a series of consecutive simulations. The simulated recharge rate for the final calibrated model was 4.8 mm/a which compares well with the rate of 5 mm/a, that was estimated from independent field experiments. The simulated freshwater heads also compared reasonably well with measured heads in the network of boreholes at the WRA. Most of the groundwater flow occurred in local systems between the ground surface and the depth of 2000 m. The travel times, pathways and exit locations of particles released from different depth horizons in the groundwater velocity field of the calibrated model were determined using a particle tracking code, TRACK3D. These results were used to select a location for a hypothetical nuclear fuel waste disposal vault that maximizes the retention of vault contaminants in a long, slow groundwater flow pathways. The selected location is about 5 km northeast of the location of Underground Research Laboratory (URL
Multigrid solution of incompressible turbulent flows by using two-equation turbulence models
Energy Technology Data Exchange (ETDEWEB)
Zheng, X.; Liu, C. [Front Range Scientific Computations, Inc., Denver, CO (United States); Sung, C.H. [David Taylor Model Basin, Bethesda, MD (United States)
1996-12-31
Most of practical flows are turbulent. From the interest of engineering applications, simulation of realistic flows is usually done through solution of Reynolds-averaged Navier-Stokes equations and turbulence model equations. It has been widely accepted that turbulence modeling plays a very important role in numerical simulation of practical flow problem, particularly when the accuracy is of great concern. Among the most used turbulence models today, two-equation models appear to be favored for the reason that they are more general than algebraic models and affordable with current available computer resources. However, investigators using two-equation models seem to have been more concerned with the solution of N-S equations. Less attention is paid to the solution method for the turbulence model equations. In most cases, the turbulence model equations are loosely coupled with N-S equations, multigrid acceleration is only applied to the solution of N-S equations due to perhaps the fact the turbulence model equations are source-term dominant and very stiff in sublayer region.
On the One-Dimensional Steady and Unsteady Porous Flow Equation
DEFF Research Database (Denmark)
Andersen, O. H.; Burcharth, H. F.
1995-01-01
Porous flow in coarse granular media is discussed theoretically with special concern given to the variation of the flow resistance with the porosity. For steady state flow, the Navier-Stokes equation is applied as a basis for the derivations. A turbulent flow equation is suggested. Alternative...... derivations based on dimensional analysis and a pipe analogy, respectively, are discussed. For non-steady state flow, the derivations are based on a cylinder/sphere analogy leading to a virtual mass coefficient. For the fully turbulent flow regime, existing experimental data values of the quadratic flow...... resistance coefficients are presented. Moreover, a simple formula for estimation of the turbulent flow coefficient is given. Virtual mass coefficients based on existing data are presented, however, no definite conclusions can be given due to the scarce data available....
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
16 reference population equations using peak expiratory flow meters
African Journals Online (AJOL)
DR. AMINU
Many formulae for predicting lung function values for Nigerians have been produced by a lot of investigators. The same principle ... equations in current use are based on linear statistical models which are subject to change and they did not express the .... that present lower limits of normal or present information from which ...
A Differential Equation for Downhill Compressible Flow in Pipes and ...
African Journals Online (AJOL)
The differential equation was first numerically solved by use of the classical fourth order Runge-Kutta method in the form of a FORTRAN program. A test of the accuracy of the solution was ... The formula was tested with a problem from the book “Fluid Mechanics and Hydraulics”. The test showed the formula to be accurate.
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
Effects of tunneling on groundwater flow and swelling of clay-sulfate rocks
Butscher, Christoph; Einstein, Herbert H.; Huggenberger, Peter
2011-11-01
Swelling of clay-sulfate rocks is a major threat in tunneling. It is triggered by the transformation of the sulfate mineral anhydrite into gypsum as a result of water inflow in anhydrite-containing layers after tunnel excavation. The present study investigates the hydraulic effects of tunneling on groundwater flow and analyzes how hydraulic changes caused by excavation lead to water inflow into anhydrite-containing layers in the tunnel area. Numerical groundwater models are used to conduct scenario simulations that allow one to relate hydrogeological conditions to rock swelling. The influence of the topographic setting, the excavation-damaged zone around the tunnel, the sealing effect of the tunnel liner, and the geological configuration are analyzed separately. The analysis is performed for synthetic situations and is complemented by a case study from a tunnel in Switzerland. The results illustrate the importance of geological and hydraulic information when assessing the risk of swelling at an actual site.
Isotope-hydrological models and calculational methods for investigation of groundwater flow
International Nuclear Information System (INIS)
Marton, L.
1982-01-01
Recharge of groundwater through a semi-confining bed is a typical hydrogeological phenomenon in quaternary deposits which are elevated to a lesser or greater degree above the surroundings. A simple hydrological model has been introduced in which the aquifer is recharged only by precipitation through a semi-permeable layer. For applying the model, it is necessary to know the age of the water or the radioisotope concentrations in some sections of the ground-water flow system. On the basis of the age, the hydraulic conductivity of the aquifer and of the semiconfining bed and the steady rate of infiltration can be calculated. Other hydraulic parameters can be determined with the help of a mathemathical model worked out by Freeze and Witherspoon. The hydrological and mathemathical models are inversely used and are complementary. The reliability and applicability of the hydrological model has been proved in practice and good results were gained in hydrogeological research carried out in Hungary. (author)
Geologic framework of the regional ground-water flow system in the Upper Deschutes Basin, Oregon
Lite, Kenneth E.; Gannett, Marshall W.
2002-12-10
Ground water is increasingly relied upon to satisfy the needs of a growing population in the upper Deschutes Basin, Oregon. Hydrogeologic studies are being undertaken to aid in management of the ground-water resource. An understanding of the geologic factors influencing ground-water flow is basic to those investigations. The geology of the area has a direct effect on the occurrence and movement of ground water. The permeability and storage properties of rock material are influenced by the proportion, size, and degree of interconnection of open spaces the rocks contain. These properties are the result of primary geologic processes such as volcanism and sedimentation, as well as subsequent processes such as faulting, weathering, or hydrothermal alteration. The geologic landscape in the study area evolved during about 30 million years of volcanic activity related to a north-south trending volcanic arc, the current manifestation of which are today’s Cascade Range volcanoes.
Selection of geohydrologic boundaries for ground-water flow models, Yucca Mountain, Nevada
International Nuclear Information System (INIS)
Downey, J.S.; Gutentag, E.D.; Kolm, K.E.
1990-01-01
The conceptual ground-water model of the southern Nevada/Death Valley, California region presented in this paper includes two aquifer systems: a shallow, intermontane, mostly unconfined aquifer composed of unconsolidated or poorly consolidated sediments and consolidated, layered volcanics, and a deep, regional multiple-layered, confined aquifer system composed of faulted and fractured carbonate and volcanic rocks. The potentiometric surfaces of both aquifer systems indicate that ground water leaks vertically from the deeper to the shallower geologic units, and that water in the shallower aquifer may not flow beyond the intermontane subbasin, whereas water in the deeper aquifer may indicate transbasinal flow to the playas in Death Valley. Most of the hydrologic boundaries of the regional aquifer systems in the Yucca Mountain region are geologically complex. Most of the existing numerical models simulating the ground-water flow system in the Yucca Mountain region are based on limited potentiometric-head data elevation and precipitation estimates, and simplified geology. These models are two-dimensional, and are not adequate. The alternative approach to estimating unknown boundary conditions for the regional ground-water flow system involves the following steps: (1) Incorporate known boundary-conditions data from the playas in Death Valley and the Ash Meadows spring line; (2) use estimated boundary data based on geological, pedological, geomorphological, botanical, and hydrological observations; (3) test these initial boundary conditions with three-dimensional models, both steady-state and transient; (4) back-calculate the boundary conditions for the northern, northwestern, northeastern and eastern flux boundaries; (5) compare these calculated values with known data during model calibration steps; and (6) adjust the model. 9 refs., 6 figs
Identification of potential groundwater flow paths using geological and geophysical data
International Nuclear Information System (INIS)
Pohlmann, K.; Andricevic, R.
1994-09-01
This project represents the first phase in the development of a methodology for generating three-dimensional equiprobable maps of hydraulic conductivity for the Nevada Test Site (NTS). In this study, potential groundwater flow paths were investigated for subsurface tuffs at Yucca Flat by studying how these units are connected. The virtual absence of site-specific hydraulic conductivity data dictates that as a first step a surrogate attribute (geophysical logs) be utilized. In this first phase, the connectivity patterns of densely welded ash-flow tuffs were studied because these tuffs are the most likely to form zones of high hydraulic conductivity. Densely welded tuffs were identified based on the response shown on resistivity logs and this information was transformed into binary indicator values. The spatial correlation of the indicator data was estimated through geostatistical methods. Equiprobable three-dimensional maps of the distribution of the densely-welded and nonwelded tuffs (i.e., subsurface heterogeneity) were then produced using a multiple indicator simulation formalism. The simulations demonstrate that resistivity logs are effective as soft data for indicating densely welded tuffs. The simulated welded tuffs reproduce the stratigraphic relationships of the welded tuffs observed in hydrogeologic cross sections, while incorporating the heterogeneity and anisotropy that is expected in this subsurface setting. Three-dimensional connectivity of the densely welded tuffs suggests potential groundwater flow paths with lengths easily over 1 km. The next phase of this investigation should incorporate other geophysical logs (e.g., gamma-gamma logs) and then calibrate the resulting soft data maps with available hard hydraulic conductivity data. The soft data maps can then augment the hard data to produce the final maps of the spatial distribution of hydraulic conductivity that can be used as input for numerical solution of groundwater flow and transport
Wei, X.; Bailey, R. T.
2017-12-01
Agricultural irrigated watersheds in semi-arid regions face challenges such as waterlogging, high soil salinity, reduced crop yield, and leaching of chemical species due to extreme shallow water tables resulting from long-term intensive irrigation. Hydrologic models can be used to evaluate the impact of land management practices on water yields and groundwater-surface water interactions in such regions. In this study, the newly developed SWAT-MODFLOW, a coupled surface/subsurface hydrologic model, is applied to a 950 km2 watershed in the Lower Arkansas River Valley (southeastern Colorado). The model accounts for the influence of canal diversions, irrigation applications, groundwater pumping, and earth canal seepage losses. The model provides a detailed description of surface and subsurface flow processes, thereby enabling detailed description of watershed processes such as runoff, infiltration, in-streamflow, three-dimensional groundwater flow in a heterogeneous aquifer system with sources and sinks (e.g. pumping, seepage to subsurface drains), and spatially-variable surface and groundwater exchange. The model was calibrated and tested against stream discharge from 5 stream gauges in the Arkansas River and its tributaries, groundwater levels from 70 observation wells, and evapotranspiration (ET) data estimated from satellite (ReSET) data during the 1999 to 2007 period. Since the water-use patterns within the study area are typical of many other irrigated river valleys in the United States and elsewhere, this modeling approach is transferable to other regions.
van der Grift, B.; Rozemeijer, J. C.; Griffioen, J.; van der Velde, Y.
2014-11-01
The retention of phosphorus in surface waters through co-precipitation of phosphate with Fe-oxyhydroxides during exfiltration of anaerobic Fe(II) rich groundwater is not well understood. We developed an experimental field set-up to study Fe(II) oxidation and P immobilization along the flow-path from groundwater into surface water in an agricultural experimental catchment of a small lowland river. We physically separated tube drain effluent from groundwater discharge before it entered a ditch in an agricultural field. Through continuous discharge measurements and weekly water quality sampling of groundwater, tube drain water, exfiltrated groundwater, and surface water, we investigated Fe(II) oxidation kinetics and P immobilization processes. The oxidation rate inferred from our field measurements closely agreed with the general rate law for abiotic oxidation of Fe(II) by O2. Seasonal changes in climatic conditions affected the Fe(II) oxidation process. Lower pH and lower temperatures in winter (compared to summer) resulted in low Fe oxidation rates. After exfiltration to the surface water, it took a couple of days to more than a week before complete oxidation of Fe(II) is reached. In summer time, Fe oxidation rates were much higher. The Fe concentrations in the exfiltrated groundwater were low, indicating that dissolved Fe(II) is completely oxidized prior to inflow into a ditch. While the Fe oxidation rates reduce drastically from summer to winter, P concentrations remained high in the groundwater and an order of magnitude lower in the surface water throughout the year. This study shows very fast immobilization of dissolved P during the initial stage of the Fe(II) oxidation process which results in P-depleted water before Fe(II) is completely depleted. This cannot be explained by surface complexation of phosphate to freshly formed Fe-oxyhydroxides but indicates the formation of Fe(III)-phosphate precipitates. The formation of Fe(III)-phosphates at redox gradients
Shim, B.
2005-12-01
Aquifer thermal energy storage (ATES) can be a cost-effective and renewable energy source, depending on site-specific thermohydraulic conditions. To design an effective ATES system, the understanding of thermohydraulic processes is necessary. The heat transfer phenomena of an aquifer heat storage system are simulated with the scenario of heat pump operation of pumping and waste water reinjection in a two layered confined aquifer model having the effect of groundwater movement. Temperature distribution of the aquifer model is generated, and hydraulic heads and temperature variations are monitored at both wells during simulation days. The average groundwater velocities are determined with two assumed hydraulic gradients set by boundary conditions, and the effect of groundwater flow are shown at the generated thermal distributions at three different depth slices. The generated temperature contour lines at the hydraulic gradient of 0.001 are shaped circular, and the center is moved less than 5 m to the east in 365 days. However at the hydraulic gradient of 0.01, the contour centers of the east well at each depth slice are moved near the east boundary and the movement of temperature distribution is increased at the lower aquifer. By the analysis of thermal interference data between two wells the efficiency of a heat pump operation model is validated, and the variation of heads is monitored at injection, pumping and stabilized state. The thermal efficiency of the ATES system model is represented as highly depended on groundwater flow velocity and direction. Therefore the hydrogeologic condition for the system site should be carefully surveyed.
On the scarcity of solutions of the equations of magnetohydrodynamic equilibria with flow
Energy Technology Data Exchange (ETDEWEB)
Nunez, Manuel [Departamento de Analisis Matematico, Universidad de Valladolid, 47005 Valladolid (Spain)], E-mail: mnjmhd@am.uva.es
2008-06-16
While particular analytic solutions to the equations of axisymmetric MHD equilibria with flow are known, it is not clear what possible choosing of the free parameters of the equation of the magnetic flux will yield a solution. The most important of these is the poloidal stream function. We show that for a given flow to be able to yield an equilibrium, the flow itself must satisfy an analogous equation to the generalized Grad-Shafranov one. The problem therefore turns out to be how common are solutions to this type of equations. It is shown that in a natural space of functions, the set of these solutions is contained within a manifold of infinite codimension: extremely small by any criteria. Hence the class of flows for which an equilibrium, even defined only locally and irrespective of boundary conditions, may be found, is highly constrained.
Rowley, Peter D.; Dixon, Gary L.; Watrus , James M.; Burns, Andrews G.; Mankinen, Edward A.; McKee, Edwin H.; Pari, Keith T.; Ekren, E. Bartlett; Patrick , William G.; Comer, John B.; Inkenbrandt, Paul C.; Krahulec, K.A.; Pinnell, Michael L.
2016-01-01
The east-central Great Basin near the Utah-Nevada border contains two great groundwater flow systems. The first, the White River regional groundwater flow system, consists of a string of hydraulically connected hydrographic basins in Nevada spanning about 270 miles from north to south. The northernmost basin is Long Valley and the southernmost basin is the Black Mountain area, a valley bordering the Colorado River. The general regional groundwater flow direction is north to south. The second flow system, the Great Salt Lake Desert regional groundwater flow system, consists of hydrographic basins that straddle
Direct test of a nonlinear constitutive equation for simple turbulent shear flows using DNS data
Schmitt, François G.
2007-10-01
Several nonlinear constitutive equations have been proposed to overcome the limitations of the linear eddy-viscosity models to describe complex turbulent flows. These nonlinear equations have often been compared to experimental data through the outputs of numerical models. Here we perform a priori analysis of nonlinear eddy-viscosity models using direct numerical simulation (DNS) of simple shear flows. In this paper, the constitutive equation is directly checked using a tensor projection which involves several invariants of the flow. This provides a 3 terms development which is exact for 2D flows, and a best approximation for 3D flows. We provide the quadratic nonlinear constitutive equation for the near-wall region of simple shear flows using DNS data, and estimate their coefficients. We show that these coefficients have several common properties for the different simple shear flow databases considered. We also show that in the central region of pipe flows, where the shear rate is very small, the coefficients of the constitutive equation diverge, indicating the failure of this representation for vanishing shears.
Jayne, Richard S.; Pollyea, Ryan M.; Dodd, Justin P.; Olson, Elizabeth J.; Swanson, Susan K.
2016-12-01
Aquifers within the Pampa del Tamarugal Basin (Atacama Desert, northern Chile) are the sole source of water for the coastal city of Iquique and the economically important mining industry. Despite this, the regional groundwater system remains poorly understood. Although it is widely accepted that aquifer recharge originates as precipitation in the Altiplano and Andean Cordillera to the east, there remains debate on whether recharge is driven primarily by near-surface groundwater flow in response to periodic flood events or by basal groundwater flux through deep-seated basin fractures. In addressing this debate, the present study quantifies spatial and temporal variability in regional-scale groundwater flow paths at 20.5°S latitude by combining a two-dimensional model of groundwater and heat flow with field observations and δ18O isotope values in surface water and groundwater. Results suggest that both previously proposed aquifer recharge mechanisms are likely influencing aquifers within the Pampa del Tamarugal Basin; however, each mechanism is operating on different spatial and temporal scales. Storm-driven flood events in the Altiplano readily transmit groundwater to the eastern Pampa del Tamarugal Basin through near-surface groundwater flow on short time scales, e.g., 100-101 years, but these effects are likely isolated to aquifers in the eastern third of the basin. In addition, this study illustrates a physical mechanism for groundwater originating in the eastern highlands to recharge aquifers and salars in the western Pampa del Tamarugal Basin over timescales of 104-105 years.
On kinetic Boltzmann equations and related hydrodynamic flows with dry viscosity
Directory of Open Access Journals (Sweden)
Nikolai N. Bogoliubov (Jr.
2007-01-01
Full Text Available A two-component particle model of Boltzmann-Vlasov type kinetic equations in the form of special nonlinear integro-differential hydrodynamic systems on an infinite-dimensional functional manifold is discussed. We show that such systems are naturally connected with the nonlinear kinetic Boltzmann-Vlasov equations for some one-dimensional particle flows with pointwise interaction potential between particles. A new type of hydrodynamic two-component Benney equations is constructed and their Hamiltonian structure is analyzed.
Model Refinement and Simulation of Groundwater Flow in Clinton, Eaton, and Ingham Counties, Michigan
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
van der Velde, Y.; Rozemeijer, J. C.; de Rooij, G. H.; van Geer, F. C.; Torfs, P. J. J. F.; de Louw, P. G. B.
2010-10-01
Identifying effective measures to reduce nutrient loads of headwaters in lowland catchments requires a thorough understanding of flow routes of water and nutrients. In this paper we assess the value of nested-scale discharge and groundwater level measurements for predictions of catchment-scale discharge and nitrate loads. In order to relate field-site measurements to the catchment-scale an upscaling approach is introduced that assumes that scale differences in flow route fluxes originate from differences in the relationship between groundwater storage and the spatial structure of the groundwater table. This relationship is characterized by the Groundwater Depth Distribution (GDD) curve that relates spatial variation in groundwater depths to the average groundwater depth. The GDD-curve was measured for a single field site (0.009 km2) and simple process descriptions were applied to relate the groundwater levels to flow route discharges. This parsimonious model could accurately describe observed storage, tube drain discharge, overland flow and groundwater flow simultaneously with Nash-Sutcliff coefficients exceeding 0.8. A probabilistic Monte Carlo approach was applied to upscale field-site measurements to catchment scales by inferring scale-specific GDD-curves from hydrographs of two nested catchments (0.4 and 6.5 km2). The estimated contribution of tube drain effluent (a dominant source for nitrates) decreased with increasing scale from 76-79% at the field-site to 34-61% and 25-50% for both catchment scales. These results were validated by demonstrating that a model conditioned on nested-scale measurements simulates better nitrate loads and better predictions of extreme discharges during validation periods compared to a model that was conditioned on catchment discharge only.
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)
Peters, J.G.
1987-01-01
The Indiana Department of Natural Resources (IDNR) is developing water-management policies designed to assess the effects of irrigation and other water uses on water supply in the basin. In support of this effort, the USGS, in cooperation with IDNR, began a study to evaluate appropriate methods for analyzing the effects of pumping on ground-water levels and streamflow in the basin 's glacial aquifer systems. Four analytical models describe drawdown for a nonleaky, confined aquifer and fully penetrating well; a leaky, confined aquifer and fully penetrating well; a leaky, confined aquifer and partially penetrating well; and an unconfined aquifer and partially penetrating well. Analytical equations, simplifying assumptions, and methods of application are described for each model. In addition to these four models, several other analytical models were used to predict the effects of ground-water pumping on water levels in the aquifer and on streamflow in local areas with up to two pumping wells. Analytical models for a variety of other hydrogeologic conditions are cited. A digital ground-water flow model was used to describe how a numerical model can be applied to a glacial aquifer system. The numerical model was used to predict the effects of six pumping plans in 46.5 sq mi area with as many as 150 wells. Water budgets for the six pumping plans were used to estimate the effect of pumping on streamflow reduction. Results of the analytical and numerical models indicate that, in general, the glacial aquifers in the basin are highly permeable. Radial hydraulic conductivity calculated by the analytical models ranged from 280 to 600 ft/day, compared to 210 and 360 ft/day used in the numerical model. Maximum seasonal pumping for irrigation produced maximum calculated drawdown of only one-fourth of available drawdown and reduced streamflow by as much as 21%. Analytical models are useful in estimating aquifer properties and predicting local effects of pumping in areas with
Fracture network model of the groundwater flow in the Romuvaara site
International Nuclear Information System (INIS)
Poteri, A.; Laitinen, M.
1997-01-01
In the study, computer codes are employed to analyse the groundwater flow patterns in the sparcely fractured intact rock at the Romuvaara site. The new fracture data gathered during the detailed site characterisation phase demonstrated that the characteristic properties of fractures can be estimated quite reliably from few boreholes and outcrops. Results obtained by employing new methods, like the use of borehole-TV, changed the fracture intensity of the potential water conducting fractures compared to the earlier model. In the preliminary site investigation phase only the orientated fractures were used to derive the parameters of the intact rock. In the present model all the fractures outside the known fracture zones are used. The hydraulic conductivity tensor of the intact rock was estimated with the fracture network model. The flow simulations were calculated for a 16 x 16 x 16 m 3 rock volume and about 2000 fractures. The flow rate distribution through the cross sectional area of the disposal canisters was calculated for a set of ten realisations and a large number of different canister positions. The total number of canister positions simulated was 2200. The flow distribution in larger volume was studied using a method that searched the flow routes of highest conductance. The flow routes were examined into north-south, east-west and vertical directions. Flow routes along homogeneous and heterogeneous fractures were compared. (21 refs.)
Considerations of a nonhomogeneous fluid in the deep groundwater flow system at Hanford
International Nuclear Information System (INIS)
Nelson, R.W.
1988-11-01
This report presents such a general theory capable of describing the flow on nonhomogeneous fluids in porous media, theory that is a composite from several disciplines including groundwater hydrology, soil physics, civil engineering, petroleum reservoir engineering, mechanics, and mathematical physics. The report discussed the conceptual basis for considering the flow of nonhomogeneous fluids. From this conceptual basis emphasis shifts to providing complete definitions and then appropriately describing those definitions in mathematical terms. Throughout the report, the necessary assumptions are stated in detail because the limitations of any theory are best assessed through careful scrutiny of the assumptions. From the mathematical definitions with appropriate functional dependence the results and constraints needed are derived to provide the general theory necessary to describe the flow of nonhomogeneous fluids in porous media. Particular attention is given to comparing the general theory with the classical theory of flow for a homogeneous fluid. Such comparison provides significant insight to the effects of variable fluid properties on subsurface flow systems. The comparisons also indicate the importance of carefully formulating subsurface flow models within the more general theoretical framework describing the flow of nonhomogeneous fluids in porous media. 29 refs.; 6 figs.; 1 tab
International Nuclear Information System (INIS)
Sykes, J.F.; Sudicky, E.A.; Normani, S.D.; McLaren, R.G.; Jensen, M.R.
2006-01-01
As part of Ontario Power Generation's Deep Geologic Repository Technology Program (DGRTP), activities have been undertaken to further the understanding of groundwater flow system evolution and dynamics within a Canadian Shield setting. This paper describes a numerical case study in which the evolution and nature of groundwater flow, as relevant to the siting and safety of a hypothetical Deep Geologic Repository (DGR) for used nuclear fuel, is explored within representative regional (∼5734 km 2 ) and sub-regional (∼83 km 2 ) Shield watersheds. The modelling strategy adopted a GIS framework that included a digital elevation model and surface hydrologic features such as rivers, lakes and wetlands. Model boundary conditions were extracted through GIS automation such that the 3-dimensional characteristics of surface relief, surface water features, in addition to, pore fluid salinities and spatially variable permeability fields could be explicitly incorporated. Further flow system detail has been incorporated in sub-regional simulations with the inclusion of an irregular curve-planar Fracture Network Model traceable to site-specific geologic attributes. Interim modelling results reveal that deep-seated regional flow systems do evolve with groundwater divides within the shallow (<300 m) flow system defined by local scale topography, in particular, major rivers and their tributaries. Within the realizations considered groundwater flow at depths of ∼700 m or more was determined to be essentially stagnant and likely diffusion dominated. The role of fracture zone interconnectivity, depth dependent salinity and spatially variable permeability distributions on flow system response to past glacial events is examined. In demonstrating a case for groundwater flow system stability it is evident that predictive modelling approaches that cannot preserve the 3-dimensional complexity of the watershed-scale groundwater flow system may lead to conclusions that are implausible
Assessment of consistent two-equation closure for forest flows
DEFF Research Database (Denmark)
Sogachev, Andrey; Cavar, Dalibor; Bechmann, Andreas
of grid turbulence and wall-bounded flow, the closure suggested is also valid for homogeneous shear flows commonly observed inside tall vegetative canopies. The present work assess the plant drag closure by comparing results of two different CFD models against observations derived over the forested area...... and can be applied for any twoequation closure. Results derived by different CFD models with k-epsilon and k-omega closure are similar and in good comparison with observations. Overall, numerical results show that the closure performs well, opening new possibilities for application to tasks related...... to the atmospheric boundary layer—where it is important to adequately account for the influences of vegetation....
International Nuclear Information System (INIS)
Bockgaard, Niclas
2011-06-01
The objective of the work was to investigate hydraulic effects of open and poorly sealed boreholes on groundwater flow conditions through simulations using a numerical groundwater model. Specifically, the boreholes KFM07A, KFM09A, and KFM09B in Forsmark and the boreholes KLX04, KLX06, and KLX10 in Laxemar were studied. The criteria for the selection of these boreholes were that the boreholes should represent typical conditions of the site, the borehole length should exceed 500 m, and that several major fractured zones should be intersected. The boreholes KFM07A and KLX06, respectively, were selected as reference boreholes for more detailed studies of different sealing schemes. The model setup of the Forsmark model followed the Forsmark 2.2 regional-scale conceptual hydrogeological model. The model domain was approximately 15 km (north-south) x 10 km (west- east) x 1.2 km (depth). The 131 deformation zones and three layers of superficial horizontal sheet joint were modelled deterministically. A stochastic discrete fracture network (DFN) representing fractures and minor deformation zones were also generated between the deterministic deformation zones inside central model volume. The side lengths of the square fractures were from 1,000 m down to 10 m. In order to resolve the details of flow in to and out from the borehole, a more detailed DFN was generated in a zone around the borehole KFM07A, where fractures down to a side length of 0.5 m were considered. The model setup of the Laxemar model followed the SDM-Site Laxemar (Laxemar 2.3) regional scale conceptual hydrogeological model. The model domain was approximately 12 km (north-south) x 20 km (west-east) x 2.1 km (depth). A number of 71 deformation zones were modelled deterministically, and one realization of a stochastic DFN, the so-called hydrogeological DFN model base case, was imported to the model. Similar to the Forsmark case, a more detailed DFN was also generated around the reference borehole KLX06. The
Energy Technology Data Exchange (ETDEWEB)
Bockgaard, Niclas [Golder Associates AB, Stockholm (Sweden)
2011-06-15
The objective of the work was to investigate hydraulic effects of open and poorly sealed boreholes on groundwater flow conditions through simulations using a numerical groundwater model. Specifically, the boreholes KFM07A, KFM09A, and KFM09B in Forsmark and the boreholes KLX04, KLX06, and KLX10 in Laxemar were studied. The criteria for the selection of these boreholes were that the boreholes should represent typical conditions of the site, the borehole length should exceed 500 m, and that several major fractured zones should be intersected. The boreholes KFM07A and KLX06, respectively, were selected as reference boreholes for more detailed studies of different sealing schemes. The model setup of the Forsmark model followed the Forsmark 2.2 regional-scale conceptual hydrogeological model. The model domain was approximately 15 km (north-south) x 10 km (west- east) x 1.2 km (depth). The 131 deformation zones and three layers of superficial horizontal sheet joint were modelled deterministically. A stochastic discrete fracture network (DFN) representing fractures and minor deformation zones were also generated between the deterministic deformation zones inside central model volume. The side lengths of the square fractures were from 1,000 m down to 10 m. In order to resolve the details of flow in to and out from the borehole, a more detailed DFN was generated in a zone around the borehole KFM07A, where fractures down to a side length of 0.5 m were considered. The model setup of the Laxemar model followed the SDM-Site Laxemar (Laxemar 2.3) regional scale conceptual hydrogeological model. The model domain was approximately 12 km (north-south) x 20 km (west-east) x 2.1 km (depth). A number of 71 deformation zones were modelled deterministically, and one realization of a stochastic DFN, the so-called hydrogeological DFN model base case, was imported to the model. Similar to the Forsmark case, a more detailed DFN was also generated around the reference borehole KLX06. The
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
Degradation of ground ice in a changing climate: the potential impact of groundwater flow
de Grandpré, I.; Fortier, D.; Stephani, E.
2011-12-01
Climate changes affecting the North West portion of Canada alter the thermal state of the permafrost and promote ground ice degradation. Melting of ground ice leads to greater water flow into the ground and to significant hydraulic changes (i.e. drainage of peatland and lakes, triggering of thermokarst and new groundwater flow patterns). Road infrastructures built on permafrost are particularly sensitive to permafrost degradation. Road construction and maintenance induce heat flux into the ground by the increase of solar radiation absorption (comparing to natural ground), the increase of snow cover on side slopes, the infiltration of water in embankment material and the migration of surface water in the active layer. The permafrost under the roads is therefore submitted to a warmer environment than in natural ground and his behavior reflects how the permafrost will act in the future with the global warming trend. The permafrost degradation dynamic under a road was studied at the Beaver Creek (Yukon) experimental site located on the Alaska Highway. Permafrost was characterized as near-zero Celcius and highly susceptible to differential thaw-settlement due to the ground ice spatial distribution. Ice-rich cryostructures typical of syngenetic permafrost (e.g. microlenticular) were abundant in the upper and lower cryostratigraphic units of fine-grained soils (Units 1, 2A, and 2C). The middle ice-poor silt layer (Unit 2B) characterized by porous cryostructure comprised the top of a buried ice-wedge network extending several meters in the underlying layers and susceptible to degradation by thermo-erosion. These particular features of the permafrost at the study site facilitated the formation of taliks (unfrozen zones) under the road which leaded to a greater water flow. We believe that water flow is promoting an acceleration of permafrost degradation by advective heat transfer. This process remains poorly studied and quantified in permafrost environment. Field data on
Directory of Open Access Journals (Sweden)
Yifeng Chen
2016-08-01
Full Text Available Even though a large number of large-scale arch dams with height larger than 200 m have been built in the world, the transient groundwater flow behaviors and the seepage control effects in the dam foundations under difficult geological conditions are rarely reported. This paper presents a case study on the transient groundwater flow behaviors in the rock foundation of Jinping I double-curvature arch dam, the world's highest dam of this type to date that has been completed. Taking into account the geological settings at the site, an inverse modeling technique utilizing the time series measurements of both hydraulic head and discharge was adopted to back-calculate the permeability of the foundation rocks, which effectively improves the uniqueness and reliability of the inverse modeling results. The transient seepage flow in the dam foundation during the reservoir impounding was then modeled with a parabolic variational inequality (PVI method. The distribution of pore water pressure, the amount of leakage, and the performance of the seepage control system in the dam foundation during the entire impounding process were finally illustrated with the numerical results.
Stepwise hydrogeological modeling and groundwater flow analysis on site scale (Step 0 and Step 1)
International Nuclear Information System (INIS)
Ohyama, Takuya; Saegusa, Hiromitsu; Onoe, Hironori
2005-05-01
One of the main goals of the Mizunami Underground Research Laboratory Project is to establish comprehensive techniques for investigation, analysis, and assessment of the deep geological environment. To achieve this goal, a variety of investigations, analysis, and evaluations have been conducted using an iterative approach. In this study, hydrogeological modeling and ground water flow analyses have been carried out using the data from surface-based investigations at Step 0 and Step 1, in order to synthesize the investigation results, to evaluate the uncertainty of the hydrogeological model, and to specify items for further investigation. The results of this study are summarized as follows: 1) As the investigation progresses Step 0 to Step 1, the understanding of groundwater flow was enhanced from Step 0 to Step 1, and the hydrogeological model could be revised, 2) The importance of faults as major groundwater flow pathways was demonstrated, 3) Geological and hydrogeological characteristics of faults with orientation of NNW and NE were shown to be especially significant. The main item specified for further investigations is summarized as follows: geological and hydrogeological characteristics of NNW and NE trending faults are important. (author)
International Nuclear Information System (INIS)
Saegusa, Hiromitsu; Takeuchi, Shinji; Maekawa, Keisuke; Osawa, Hideaki; Semba, Takeshi
2011-01-01
It is important for site characterization projects to manage the decision-making process with transparency and traceability and to transfer the technical know-how accumulated during the research and development to the implementing phase and to future generations. The modeling for a geological environment is to be used to synthesize investigation results. Evaluation of the impact of uncertainties in the model is important to identify and prioritize key issues for further investigations. Therefore, a plan for site characterization should be made based on the results of the modeling. The aim of this study is to support for the planning of initial surface-based site characterization based on the technical know-how accumulated from the Mizunami Underground Research Laboratory Project and the Horonobe Underground Research Laboratory Project. These projects are broad scientific studies of the deep geological environment that are a basis for research and development for the geological disposal of high-level radioactive wastes. In this study, the work-flow of the groundwater flow modeling, which is one of the geological environment models, and is to be used for setting the area for the geological environment modeling and for groundwater flow characterization, and the related decision-making process using literature data have been summarized. (author)
Inversion of collective matter flow and equation of state
International Nuclear Information System (INIS)
Peter, J.
1992-03-01
The multidetector array Mur + Tonneau has been used to perform a 4π detection of charged particles and fragments emitted in reactions at energies ranging from 25 to 95 MeV/u. The collective transverse momentum in the reaction plane (sidewards flow parameter) is observed to strongly vary as a function of impact parameter and incident energy. The measured values have to be corrected for the effects due to the error on the reaction plane determination and to the detector limitations. Those limitations caused by the method itself are more important than those caused by the detector. The flow value changes from negative values (negative scattering at low energies). The inversion (or balance) energy is in the range 50-100 MeV/u, depending on the system and impact parameter value. Comparisons between experimental data and theoretical values are shown for the system 40 Ar + 27 Al. These studies (BUU, Landau-Vlasov, QMD) show that the flow, and especially the inversion energy, is sensitive to the nucleon-nucleon cross section σNN in medium. The data indicate that a momentum dependent effective interaction should be used. Then, the flow value is not much sensitive to the incompressibility modulus K, but possibly in peripheral collisions. Additional observables should be used. The azimuthal distribution of mid-rapidity particles indicates a rotation-like behaviour of the interaction region
Fitzpatrick, Faith A.; Peppler, Marie C.; Saad, David A.; Pratt, Dennis M.; Lenz, Bernard N.
2015-01-01
In 2002–03, the U.S. Geological Survey conducted a study of the geomorphic, flood, and groundwater-flow characteristics of five Bayfield Peninsula streams, Wisconsin (Cranberry River, Bark River, Raspberry River, Sioux River, and Whittlesey Creek) to determine the physical limitations for brook-trout habitat. The goals of the study were threefold: (1) to describe geomorphic characteristics and processes, (2) to determine how land-cover characteristics affect flood peaks, and (3) to determine how regional groundwater flow patterns affect base flow.
Grubbs, J.W.
1995-01-01
Temporal and spatial distributions of ground-water inflow to, and leakage from Lake Five-O, a softwater, seepage lake in northwestern Florida, were evaluated using hydrologic data and simulation models of the shallow ground-water system adjacent to the lake. The simulation models indicate that ground-water inflow to the lake and leakage from the lake to the ground-water system are the dominant components in the total inflow (precipitation plus ground-water inflow) and total outflow (evaporation plus leakage) budgets of Lake Five-O. Simlulated ground-water inflow and leakage were approximately 4 and 5 times larger than precipitation inputs and evaporative losses, respectively, during calendar years 1989-90. Exchanges of water between Lake Five-O and the ground-water system were consistently larger than atmospheric-lake exchanges. A consistent pattern of shallow ground-water inflow and deep leakage was also evident throughout the study period. The mean time of travel from ground-water that discharges at Lake Five-O (time from recharge at the water table to discharge at the lake) was estimated to be within a range of 3 to 6 years. Flow-path evaluations indicated that the intermediate confining unit probably has a negligible influence on the geochemistry of ground-water inflow to Lake Five-O. The hydrologic budgets and flow-path evaluations provide critical information for developing geochemical budgets for Lake Five-O and for improving the understanding of the relative importance of various processes that regulate the acid-neutralizing capacity of softwater seepage lakes in Florida.
Directory of Open Access Journals (Sweden)
Şaban YURTÇU
2006-02-01
Full Text Available In this study, modeling of the effect of rainfall, flow and evaporation as independent variables on the change of underground water levels as dependent variables were investigated by fuzzy logic (FL. In the study, total 396 values taken from six observation stations belong to Afyon inferior basin in Akarçay from 1977 to 1989 years were used. Using the monthly average values of stations, the change of underground water level was modeled by FL. It is observed that the results obtained from FL and the observations are compatible with each other. This shows FL modeling can be used to estimate groundwater levels from the appropriate meteorological value.
Goto, Tada-nori; Kondo, Kazuya; Ito, Rina; Esaki, Keisuke; Oouchi, Yasuo; Abe, Yutaka; Tsujimura, Maki
2012-01-01
Self-potential (SP) measurements were conducted at Mt. Tsukuba, Japan, which is a nonvolcanic mountain, to infer groundwater flow system in the mountain. Survey routes were set around the northern slope, and the reliability of observed SP anomaly was checked by using SP values along parallel survey routes; the error was almost within 10 mV. The FFT analysis of the spatial SP distribution allows us a separation of raw data into two components with shorter and longer wavelength. In the shorter ...
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.
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.
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
Tesoriero, Anthony J.; Liebscher, Hugh; Cox, Stephen E.
2000-01-01
The rate and mechanism of nitrate removal along and between groundwater flow paths were investigated using a series of well nests screened in an unconfined sand and gravel aquifer. Intensive agricultural activity in this area has resulted in nitrate concentrations in groundwater often exceeding drinking water standards. Both the extent and rate of denitrification varied depending on the groundwater flow path. While little or no denitrification occurred in much of the upland portions of the aquifer, a gradual redox gradient is observed as aerobic upland groundwater moves deeper in the aquifer. In contrast, a sharp shallow redox gradient is observed adjacent to a third‐order stream as aerobic groundwater enters reduced sediments. An essentially complete loss of nitrate concurrent with increases in excess N2 provide evidence that denitrification occurs as groundwater enters this zone. Electron and mass balance calculations suggest that iron sulfide (e.g., pyrite) oxidation is the primary source of electrons for denitrification. Denitrification rate estimates were based on mass balance calculations using nitrate and excess N2 coupled with groundwater travel times. Travel times were determined using a groundwater flow model and were constrained by chlorofluorocarbon‐based age dates. Denitrification rates were found to vary considerably between the two areas where denitrification occurs. Denitrification rates in the deep, upland portions of the aquifer were found to range from from 1.0 to 2.7 mM of N per year. Potential denitrification rates in groundwater adjacent to the stream may be much faster, with rates up to 140 mM per year based on an in situ experiment conducted in this zone.
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)
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.
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
International Nuclear Information System (INIS)
Brereton, N.R.; McEwen, T.J.; Lee, M.K.
1987-01-01
The Strath Halladale Granite in the region around Altnabreac, northern Scotland, United Kingdom, has been studied with a view to establishing a relationship between the regional distribution of faults and fracture zones, surface discharges of groundwater, and groundwater flow systems. A major component of the groundwater flow is through the rock fractures. Because of the extensive superficial cover the surface expression of major fractures was difficult to identify from the limited surface exposures. Geophysical surveys and aerial photography enabled the authors to define lineations which could be related to the presence of fractures. The areal distribution of groundwater spring discharges was mapped using thermal infrared line scan techniques. The distribution of these springs has been studied to assess their relationships to surface lineaments and to correlations with geophysical and fracture mapping data. copyright American Geophysical Union 1987
Modelling free surface aquifers to analyze the interaction between groundwater and sinuous streams
DEFF Research Database (Denmark)
Balbarini, Nicola; Boon, W. M.; Bjerg, Poul Løgstrup
and errors. In addition, when streams are sinuous, groundwater flow is truly 3-dimensional, with strong vertical flows and sharp changes in horizontal direction. Here 3 different approaches to simulating free surface aquifers are compared for simulating groundwater-stream interaction. The aim of the models......: a saturated-unsaturated flow model, moving mesh, and a new coordinate transformation. The saturated/unsaturated model couples the saturated groundwater flow equation with a solution of Richards equation. The moving mesh solves the saturated groundwater equation with a free surface and deformable numerical...... finite element mesh. Finally, the new coordinate transform method employs a coordinate transform so that the saturated groundwater flow equation is solved on a fixed finite element mesh with a stationary free surface. This paper describes in detail the new coordinate transform method. It employs...
Hu, R.; Liu, Q.
2016-12-01
For civil engineering projects, especially in the subsurface with groundwater, the artificial ground freezing (AGF) method has been widely used. Commonly, a refrigerant is circulated through a pre-buried pipe network to form a freezing wall to support the construction. In many cases, the temperature change is merely considered as a result of simple heat conduction. However, the influence of the water-ice phase change on the flow properties should not be neglected, if large amount of groundwater with high flow velocities is present. In this work, we perform a 2D modelling (software: Comsol Multiphysics) of an AFG project of a metro tunnel in Southern China, taking groundwater flow into account. The model is validated based on in-situ measurement of groundwater flow and temperature. We choose a cross section of this horizontal AGF project and set up a model with horizontal groundwater flow normal to the axial of the tunnel. The Darcy velocity is a coupling variable and related to the temperature field. During the phase change of the pore water and the decrement of permeability in freezing zone, we introduce a variable of effective hydraulic conductivity which is described by a function of temperature change. The energy conservation problem is solved by apparent heat capacity method and the related parameter change is described by a step function (McKenzie, et. al. 2007). The results of temperature contour maps combined with groundwater flow velocity at different times indicate that the freezing wall appears in an asymmetrical shape along the groundwater flow direction. It forms slowly and on the upstream side the thickness of the freezing wall is thinner than that on the downstream side. The closure time of the freezing wall increases at the middle of the both up and downstream sides. The average thickness of the freezing wall on the upstream side is mostly affected by the groundwater flow velocity. With the successful validation of this model, this numerical
Rubinato, Matteo; Martins, Ricardo; Kesserwani, Georges; Leandro, Jorge; Djordjević, Slobodan; Shucksmith, James
2017-09-01
The linkage between sewer pipe flow and floodplain flow is recognised to induce an important source of uncertainty within two-dimensional (2D) urban flood models. This uncertainty is often attributed to the use of empirical hydraulic formulae (the one-dimensional (1D) weir and orifice steady flow equations) to achieve data-connectivity at the linking interface, which require the determination of discharge coefficients. Because of the paucity of high resolution localised data for this type of flows, the current understanding and quantification of a suitable range for those discharge coefficients is somewhat lacking. To fulfil this gap, this work presents the results acquired from an instrumented physical model designed to study the interaction between a pipe network flow and a floodplain flow. The full range of sewer-to-surface and surface-to-sewer flow conditions at the exchange zone are experimentally analysed in both steady and unsteady flow regimes. Steady state measured discharges are first analysed considering the relationship between the energy heads from the sewer flow and the floodplain flow; these results show that existing weir and orifice formulae are valid for describing the flow exchange for the present physical model, and yield new calibrated discharge coefficients for each of the flow conditions. The measured exchange discharges are also integrated (as a source term) within a 2D numerical flood model (a finite volume solver to the 2D Shallow Water Equations (SWE)), which is shown to reproduce the observed coefficients. This calibrated numerical model is then used to simulate a series of unsteady flow tests reproduced within the experimental facility. Results show that the numerical model overestimated the values of mean surcharge flow rate. This suggests the occurrence of additional head losses in unsteady conditions which are not currently accounted for within flood models calibrated in steady flow conditions.
Energy Technology Data Exchange (ETDEWEB)
Jordan, Preston D.; Oldenburg, Curtis M.; Su, Grace W.
2005-02-24
This report presents a continuation from Oldenburg et al. (2002) of analysis of the hydrogeology, In-Situ Permeable Flow Sensor (ISPFS) results, aquifer response, and changes in the trichloroethylene (TCE) groundwater plume at Operational Unit 1 (OU 1) adjacent to the former Fritzsche Army Airfield at the former Fort Ord Army Base, located on Monterey Bay in northern Monterey County. Fuels and solvents were burned on a portion of OU 1 called the Fire Drill Area (FDA) during airport fire suppression training between 1962 and 1985. This activity resulted in soil and groundwater contamination in the unconfined A-aquifer. In the late 1980's, soil excavation and bioremediation were successful in remediating soil contamination at the site. Shortly thereafter, a groundwater pump, treat, and recharge system commenced operation. This system has been largely successful at remediating groundwater contamination at the head of the groundwater plume. However, a trichloroethylene (TCE) groundwater plume extends approximately 3000 ft (900 m) to the northwest away from the FDA. In the analyses presented here, we augment our prior work (Oldenburg et al., 2002) with new information including treatment-system totalizer data, recent water-level and chemistry data, and data collected from new wells to discern trends in contaminant migration and groundwater flow that may be useful for ongoing remediation efforts. Some conclusions from the prior study have been modified based on these new analyses, and these are pointed out clearly in this report.
Python tools for rapid development, calibration, and analysis of generalized groundwater-flow models
Starn, J. J.; Belitz, K.
2014-12-01
National-scale water-quality data sets for the United States have been available for several decades; however, groundwater models to interpret these data are available for only a small percentage of the country. Generalized models may be adequate to explain and project groundwater-quality trends at the national scale by using regional scale models (defined as watersheds at or between the HUC-6 and HUC-8 levels). Coast-to-coast data such as the National Hydrologic Dataset Plus (NHD+) make it possible to extract the basic building blocks for a model anywhere in the country. IPython notebooks have been developed to automate the creation of generalized groundwater-flow models from the NHD+. The notebook format allows rapid testing of methods for model creation, calibration, and analysis. Capabilities within the Python ecosystem greatly speed up the development and testing of algorithms. GeoPandas is used for very efficient geospatial processing. Raster processing includes the Geospatial Data Abstraction Library and image processing tools. Model creation is made possible through Flopy, a versatile input and output writer for several MODFLOW-based flow and transport model codes. Interpolation, integration, and map plotting included in the standard Python tool stack also are used, making the notebook a comprehensive platform within on to build and evaluate general models. Models with alternative boundary conditions, number of layers, and cell spacing can be tested against one another and evaluated by using water-quality data. Novel calibration criteria were developed by comparing modeled heads to land-surface and surface-water elevations. Information, such as predicted age distributions, can be extracted from general models and tested for its ability to explain water-quality trends. Groundwater ages then can be correlated with horizontal and vertical hydrologic position, a relation that can be used for statistical assessment of likely groundwater-quality conditions
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
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.