WorldWideScience

Sample records for groundwater flow zones

  1. Flow pathways in the evolving critical zone - insights from hydraulic groundwater theory

    Science.gov (United States)

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    B. Arnold; T. Corbet

    2001-12-18

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

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

    International Nuclear Information System (INIS)

    Geier, Joel Edward

    2004-12-01

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

  4. Prediction of groundwater flowing well zone at An-Najif Province, central Iraq using evidential belief functions model and GIS.

    Science.gov (United States)

    Al-Abadi, Alaa M; Pradhan, Biswajeet; Shahid, Shamsuddin

    2015-10-01

    The objective of this study is to delineate groundwater flowing well zone potential in An-Najif Province of Iraq in a data-driven evidential belief function model developed in a geographical information system (GIS) environment. An inventory map of 68 groundwater flowing wells was prepared through field survey. Seventy percent or 43 wells were used for training the evidential belief functions model and the reset 30 % or 19 wells were used for validation of the model. Seven groundwater conditioning factors mostly derived from RS were used, namely elevation, slope angle, curvature, topographic wetness index, stream power index, lithological units, and distance to the Euphrates River in this study. The relationship between training flowing well locations and the conditioning factors were investigated using evidential belief functions technique in a GIS environment. The integrated belief values were classified into five categories using natural break classification scheme to predict spatial zoning of groundwater flowing well, namely very low (0.17-0.34), low (0.34-0.46), moderate (0.46-0.58), high (0.58-0.80), and very high (0.80-0.99). The results show that very low and low zones cover 72 % (19,282 km(2)) of the study area mostly clustered in the central part, the moderate zone concentrated in the west part covers 13 % (3481 km(2)), and the high and very high zones extended over the northern part cover 15 % (3977 km(2)) of the study area. The vast spatial extension of very low and low zones indicates that groundwater flowing wells potential in the study area is low. The performance of the evidential belief functions spatial model was validated using the receiver operating characteristic curve. A success rate of 0.95 and a prediction rate of 0.94 were estimated from the area under relative operating characteristics curves, which indicate that the developed model has excellent capability to predict groundwater flowing well zones. The produced map of groundwater

  5. Review of ground-water flow and transport models in the unsaturated zone

    Energy Technology Data Exchange (ETDEWEB)

    Oster, C.A.

    1982-11-01

    Models of partially saturated flow and transport in porous media have application in the analysis of existing as well as future low-level radioactive waste facilities located above the water table. An extensive literature search along with telephone and mail correspondence with recognized leading experts in the field, was conducted to identify computer models suitable for studies of low-level radioactive waste facilities located in the unsaturated zone. Fifty-five existing models were identified as potentially useful. Ten of these models were selected for further examination. This report contains a statement of the ground-water flow-contaminant transport problem, a discussion of those methods used to reduce the physical problem to a computer model, a brief discussion about the data requirements of these models. The procedure used to select the ten codes for further discussion is given, along with a list of these models. Finally, the Appendices contain the data about the fifty-five codes examined. Specifically Appendix D contains the detailed discussion of each of the ten selected codes. Included in each discussion are such items which a potential user requires in determining whether the code is suitable for his applications. Appendix E contains brief summary information about each of the fifty-five codes. Included in the summaries are identification data, authors, pertinent references, and model type.

  6. Review of ground-water flow and transport models in the unsaturated zone

    International Nuclear Information System (INIS)

    Oster, C.A.

    1982-11-01

    Models of partially saturated flow and transport in porous media have application in the analysis of existing as well as future low-level radioactive waste facilities located above the water table. An extensive literature search along with telephone and mail correspondence with recognized leading experts in the field, was conducted to identify computer models suitable for studies of low-level radioactive waste facilities located in the unsaturated zone. Fifty-five existing models were identified as potentially useful. Ten of these models were selected for further examination. This report contains a statement of the ground-water flow-contaminant transport problem, a discussion of those methods used to reduce the physical problem to a computer model, a brief discussion about the data requirements of these models. The procedure used to select the ten codes for further discussion is given, along with a list of these models. Finally, the Appendices contain the data about the fifty-five codes examined. Specifically Appendix D contains the detailed discussion of each of the ten selected codes. Included in each discussion are such items which a potential user requires in determining whether the code is suitable for his applications. Appendix E contains brief summary information about each of the fifty-five codes. Included in the summaries are identification data, authors, pertinent references, and model type

  7. Unsaturated-zone fast-path flow calculations for Yucca Mountain groundwater travel time analyses (GWTT-94)

    International Nuclear Information System (INIS)

    Arnold, B.W.; Altman, S.J.; Robey, T.H.

    1995-08-01

    Evaluation of groundwater travel time (GWTT) is required as part of the investigation of the suitability of Yucca Mountain as a potential high-level nuclear-waste repository site. The Nuclear Regulatory Commission's GWTT regulation is considered to be a measure of the intrinsic ability of the site to contain radionuclide releases from the repository. The work reported here is the first step in a program to provide an estimate of GWTT at the Yucca Mountain site in support of the DOE's Technical Site Suitability and as a component of a license application. Preliminary estimation of the GWTT distribution in the unsaturated zone was accomplished using a numerical model of the physical processes of groundwater flow in the fractured, porous medium of the bedrock. Based on prior investigations of groundwater flow at the site, fractures are thought to provide the fastest paths for groundwater flow; conditions that lead to flow in fractures were investigated and simulated. Uncertainty in the geologic interpretation of Yucca Mountain was incorporated through the use of geostatistical simulations, while variability of hydrogeologic parameters within each unit was accounted for by the random sampling of parameter probability density functions. The composite-porosity formulation of groundwater flow was employed to simulate flow in both the matrix and fracture domains. In this conceptualization, the occurrence of locally saturated conditions within the unsaturated zone is responsible for the initiation of fast-path flow through fractures. The results of the GWTT-94 study show that heterogeneity in the hydraulic properties of the model domain is an important factor in simulating local regions of high groundwater saturation. Capillary-pressure conditions at the surface boundary influence the extent of the local saturation simulated

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

    International Nuclear Information System (INIS)

    Molinero, J.; Samper, J.

    2003-01-01

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

  9. Determining flow, recharge, and vadose zone drainage in an unconfined aquifer from groundwater strontium isotope measurements, Pasco Basin, WA

    International Nuclear Information System (INIS)

    2004-01-01

    Strontium isotope compositions (87Sr/86Sr) measured in groundwater samples from 273 wells in the Pasco Basin unconfined aquifer below the Hanford Site show large and systematic variations that provide constraints on groundwater recharge, weathering rates of the aquifer host rocks, communication between unconfined and deeper confined aquifers, and vadose zone-groundwater interaction. The impact of millions of cubic meters of wastewater discharged to the vadose zone (103-105 times higher than ambient drainage) shows up strikingly on maps of groundwater 87Sr/86Sr. Extensive access through the many groundwater monitoring wells at the site allows for an unprecedented opportunity to evaluate the strontium geochemistry of a major aquifer, hosted primarily in unconsolidated sediments, and relate it to both long term properties and recent disturbances. Groundwater 87Sr/86Sr increases systematically from 0.707 to 0.712 from west to east across the Hanford Site, in the general direction of groundwater flow, as a result of addition of Sr from the weathering of aquifer sediments and from diffuse drainage through the vadose zone. The lower 87Sr/86Sr groundwater reflects recharge waters that have acquired Sr from Columbia River Basalts. Based on a steady-state model of Sr reactive transport and drainage, there is an average natural drainage flux of 0-1.4 mm/yr near the western margin of the Hanford Site, and ambient drainage may be up to 30 mm/yr in the center of the site assuming an average bulk rock weathering rate of 10-7.5 g/g/yr

  10. 14C age reassessment of groundwater from the discharge zone due to cross-flow mixing in the deep confined aquifer

    Science.gov (United States)

    Mao, Xumei; Wang, Hua; Feng, Liang

    2018-05-01

    In a groundwater flow system, the age of groundwater should gradually increase from the recharge zone to the discharge zone within the same streamline. However, it is occasionally observed that the groundwater age becomes younger in the discharge zone in the piedmont alluvial plain, and the oldest age often appears in the middle of the plain. A new set of groundwater chemistry and isotopes was employed to reassess the groundwater 14C ages from the discharge zone in the North China Plain (NCP). Carbonate precipitation, organic matter oxidation and cross-flow mixing in the groundwater from the recharge zone to the discharge zone are recognized according to the corresponding changes of HCO3- (or DIC) and δ13C in the same streamline of the third aquifer of the NCP. The effects of carbonate precipitation and organic matter oxidation are calibrated with a 13C mixing model and DIC correction, but these corrected 14C ages seem unreasonable because they grow younger from the middle plain to the discharge zone in the NCP. The relationship of Cl- content and the recharge distance is used to estimate the expected Cl- content in the discharge zone, and ln(a14C)/Cl is proposed to correct the a14C in groundwater for the effect of cross-flow mixing. The 14C ages were reassessed with the corrected a14C due to the cross-flow mixing varying from 1.25 to 30.58 ka, and the groundwater becomes older gradually from the recharge zone to the discharge zone. The results suggest that the reassessed 14C ages are more reasonable for the groundwater from the discharge zone due to cross-flow mixing.

  11. Use of Interface Treatment to Reduce Emissions from Residuals in Lower Permeability Zones to Groundwater flowing Through More Permeable Zones (Invited)

    Science.gov (United States)

    Johnson, P.; Cavanagh, B.; Clifton, L.; Daniels, E.; Dahlen, P.

    2013-12-01

    Many soil and groundwater remediation technologies rely on fluid flow for contaminant extraction or reactant delivery (e.g., soil vapor extraction, pump and treat, in situ chemical oxidation, air sparging, enhanced bioremediation). Given that most unconsolidated and consolidated settings have permeability contrasts, the outcome is often preferential treatment of more permeable zones and ineffective treatment of the lower permeability zones. When this happens, post-treatment contaminant emissions from low permeability zone residuals can cause unacceptable long-term impacts to groundwater in the transmissive zones. As complete remediation of the impacted lower permeability zones may not be practicable with conventional technologies, one might explore options that lead to reduction of the contaminant emissions to acceptable levels, rather than full remediation of the lower permeability layers. This could be accomplished either by creating a sustained emission reaction/attenuation zone at the high-low permeability interface, or by creating a clean soil zone extending sufficiently far into the lower permeability layer to cause the necessary reduction in contaminant concentration gradient and diffusive emission. These options are explored in proof-of-concept laboratory-scale physical model experiments. The physical models are prepared with two layers of contrasting permeability and either dissolved matrix storage or nonaqueous phase liquid (NAPL) in the lower permeability layer. A dissolved oxidant is then delivered to the interface via flow across the higher permeability layer and changes in contaminant emissions from the low permeability zone are monitored before, during, and after oxidant delivery. The use of three oxidants (dissolved oxygen, hydrogen peroxide and sodium persulfate) for treatment of emissions from petroleum hydrocarbon residuals is examined.

  12. Preferential Flow Paths In A Karstified Spring Catchment: A Study Of Fault Zones As Conduits To Rapid Groundwater Flow

    Science.gov (United States)

    Kordilla, J.; Terrell, A. N.; Veltri, M.; Sauter, M.; Schmidt, S.

    2017-12-01

    In this study we model saturated and unsaturated flow in the karstified Weendespring catchment, located within the Leinetal graben in Goettingen, Germany. We employ the finite element COMSOL Multiphysics modeling software to model variably saturated flow using the Richards equation with a van Genuchten type parameterization. As part of the graben structure, the Weende spring catchment is intersected by seven fault zones along the main flow path of the 7400 m cross section of the catchment. As the Weende spring is part of the drinking water supply in Goettingen, it is particularly important to understand the vulnerability of the catchment and effect of fault zones on rapid transport of contaminants. Nitrate signals have been observed at the spring only a few days after the application of fertilizers within the catchment at a distance of approximately 2km. As the underlying layers are known to be highly impermeable, fault zones within the area are likely to create rapid flow paths to the water table and the spring. The model conceptualizes the catchment as containing three hydrogeological limestone units with varying degrees of karstification: the lower Muschelkalk limestone as a highly conductive layer, the middle Muschelkalk as an aquitard, and the upper Muschelkalk as another conductive layer. The fault zones are parameterized based on a combination of field data from quarries, remote sensing and literary data. The fault zone is modeled considering the fracture core as well as the surrounding damage zone with separate, specific hydraulic properties. The 2D conceptual model was implemented in COMSOL to study unsaturated flow at the catchment scale using van Genuchten parameters. The study demonstrates the importance of fault zones for preferential flow within the catchment and its effect on the spatial distribution of vulnerability.

  13. Effects of Low-Permeability Layers in the Hyporheic Zone on Oxygen Consumption Under Losing and Gaining Groundwater Flow Conditions

    Science.gov (United States)

    Arnon, S.; Krause, S.; Gomez-Velez, J. D.; De Falco, N.

    2017-12-01

    Recent studies at the watershed scale have demonstrated the dominant role that river bedforms play in driving hyporheic exchange and constraining biogeochemical processes along river corridors. At the reach and bedform scales, modeling studies have shown that sediment heterogeneity significantly modifies hyporheic flow patterns within bedforms, resulting in spatially heterogeneous biogeochemical processes. In this work, we summarize a series of flume experiments to evaluate the effect that low-permeability layers, representative of structural heterogeneity, have on hyporheic exchange and oxygen consumption in sandy streambeds. In this case, we systematically changed the geometry of the heterogeneities, the surface channel flow driving the exchange, and groundwater fluxes (gaining/losing) modulating the exchange. The flume was packed with natural sediments, which were amended with compost to minimize carbon limitations. Structural heterogeneities were represented by continuous and discontinuous layers of clay material. Flow patterns were studied using dye imaging through the side walls. Oxygen distribution in the streambed was measured using planar optodes. The experimental observations revealed that the clay layer had a significant effect on flow patterns and oxygen distribution in the streambed under neutral and losing conditions. Under gaining conditions, the aerobic zone was limited to the upper sections of the bedform and thus was less influenced by the clay layers that were located at a depth of 1-3 cm below the water-sediment interface. We are currently analyzing the results with a numerical flow and transport model to quantify the reactions rates under the different flow conditions and spatial sediment structures. Our preliminary results enable us to show the importance of the coupling between flow conditions, local heterogeneity within the streambed and oxygen consumption along bed forms and are expected to improve our ability to model the effect of stream-groundwater

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

    Science.gov (United States)

    Misut, Paul; Aphale, Omkar

    2014-01-01

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

  15. Redox zone II. Coupled modeling of groundwater flow, solute transport, chemical reactions and microbial processes in the Aespoe island

    Energy Technology Data Exchange (ETDEWEB)

    Samper, Javier; Molinero, Jorge; Changbing Yang; Guoxiang Zhang [Univ. Da Coruna (Spain)

    2003-12-01

    The Redox Zone Experiment was carried out at the Aespoe HRL in order to study the redox behaviour and the hydrochemistry of an isolated vertical fracture zone disturbed by the excavation of an access tunnel. Overall results and interpretation of the Redox Zone Project were reported by Banwart et al. Later, Banwart presented a summary of the hydrochemistry of the Redox Zone Experiment. Coupled groundwater flow and reactive transport models of this experiment were carried out by Molinero who proposed a revised conceptual model for the hydrogeology of the Redox Zone Experiment which could explain simultaneously measured drawdown and salinity data. The numerical model was found useful to understand the natural system. Several conclusions were drawn about the redox conditions of recharge waters, cation exchange capacity of the fracture zone and the role of mineral phases such as pyrite, calcite, hematite and goethite. This model could reproduce the measured trends of dissolved species, except for bicarbonate and sulphate which are affected by microbially-mediated processes. In order to explore the role of microbial processes, a coupled numerical model has been constructed which accounts for water flow, reactive transport and microbial processes. The results of this model is presented in this report. This model accounts for groundwater flow and reactive transport in a manner similar to that of Molinero and extends the preliminary microbial model of Zhang by accounting for microbially-driven organic matter fermentation and organic matter oxidation. This updated microbial model considers simultaneously the fermentation of particulate organic matter by yeast and the oxidation of dissolved organic matter, a product of fermentation. Dissolved organic matter is produced by yeast and serves also as a substrate for iron-reducing bacteria. Model results reproduce the observed increase in bicarbonate and sulfaphe concentration, thus adding additional evidence for the possibility

  16. Redox zone II. Coupled modeling of groundwater flow, solute transport, chemical reactions and microbial processes in the Aespoe island

    International Nuclear Information System (INIS)

    Samper, Javier; Molinero, Jorge; Changbing Yang; Guoxiang Zhang

    2003-12-01

    The Redox Zone Experiment was carried out at the Aespoe HRL in order to study the redox behaviour and the hydrochemistry of an isolated vertical fracture zone disturbed by the excavation of an access tunnel. Overall results and interpretation of the Redox Zone Project were reported by Banwart et al. Later, Banwart presented a summary of the hydrochemistry of the Redox Zone Experiment. Coupled groundwater flow and reactive transport models of this experiment were carried out by Molinero who proposed a revised conceptual model for the hydrogeology of the Redox Zone Experiment which could explain simultaneously measured drawdown and salinity data. The numerical model was found useful to understand the natural system. Several conclusions were drawn about the redox conditions of recharge waters, cation exchange capacity of the fracture zone and the role of mineral phases such as pyrite, calcite, hematite and goethite. This model could reproduce the measured trends of dissolved species, except for bicarbonate and sulphate which are affected by microbially-mediated processes. In order to explore the role of microbial processes, a coupled numerical model has been constructed which accounts for water flow, reactive transport and microbial processes. The results of this model is presented in this report. This model accounts for groundwater flow and reactive transport in a manner similar to that of Molinero and extends the preliminary microbial model of Zhang by accounting for microbially-driven organic matter fermentation and organic matter oxidation. This updated microbial model considers simultaneously the fermentation of particulate organic matter by yeast and the oxidation of dissolved organic matter, a product of fermentation. Dissolved organic matter is produced by yeast and serves also as a substrate for iron-reducing bacteria. Model results reproduce the observed increase in bicarbonate and sulfaphe concentration, thus adding additional evidence for the possibility

  17. Status of understanding of the saturated-zone ground-water flow system at Yucca Mountain, Nevada, as of 1995

    Energy Technology Data Exchange (ETDEWEB)

    Luckey, R.R.; Tucci, P.; Faunt, C.C.; Ervin, E.M. [and others

    1996-12-31

    Yucca Mountain, which is being studied extensively because it is a potential site for a high-level radioactive-waste repository, consists of a thick sequence of volcanic rocks of Tertiary age that are underlain, at least to the southeast, by carbonate rocks of Paleozoic age. Stratigraphic units important to the hydrology of the area include the alluvium, pyroclastic rocks of Miocene age (the Timber Mountain Group; the Paintbrush Group; the Calico Hills Formation; the Crater Flat Group; the Lithic Ridge Tuff; and older tuffs, flows, and lavas beneath the Lithic Ridge Tuff), and sedimentary rocks of Paleozoic age. The saturated zone generally occurs in the Calico Hills Formation and stratigraphically lower units. The saturated zone is divided into three aquifers and two confining units. The flow system at Yucca Mountain is part of the Alkali Flat-Furnace Creek subbasin of the Death Valley groundwater basin. Variations in the gradients of the potentiometric surface provided the basis for subdividing the Yucca Mountain area into zones of: (1) large hydraulic gradient where potentiometric levels change at least 300 meters in a few kilometers; (2) moderate hydraulic gradient where potentiometric levels change about 45 meters in a few kilometers; and (3) small hydraulic gradient where potentiometric levels change only about 2 meters in several kilometers. Vertical hydraulic gradients were measured in only a few boreholes around Yucca Mountain; most boreholes had little change in potentiometric levels with depth. Limited hydraulic testing of boreholes in the Yucca Mountain area indicated that the range in transmissivity was more than 2 to 3 orders of magnitude in a particular hydrogeologic unit, and that the average values for the individual hydrogeologic units generally differed by about 1 order of magnitude. The upper volcanic aquifer seems to be the most permeable hydrogeologic unit, but this conclusion was based on exceedingly limited data.

  18. Status of understanding of the saturated-zone ground-water flow system at Yucca Mountain, Nevada, as of 1995

    International Nuclear Information System (INIS)

    Luckey, R.R.; Tucci, P.; Faunt, C.C.; Ervin, E.M.

    1996-01-01

    Yucca Mountain, which is being studied extensively because it is a potential site for a high-level radioactive-waste repository, consists of a thick sequence of volcanic rocks of Tertiary age that are underlain, at least to the southeast, by carbonate rocks of Paleozoic age. Stratigraphic units important to the hydrology of the area include the alluvium, pyroclastic rocks of Miocene age (the Timber Mountain Group; the Paintbrush Group; the Calico Hills Formation; the Crater Flat Group; the Lithic Ridge Tuff; and older tuffs, flows, and lavas beneath the Lithic Ridge Tuff), and sedimentary rocks of Paleozoic age. The saturated zone generally occurs in the Calico Hills Formation and stratigraphically lower units. The saturated zone is divided into three aquifers and two confining units. The flow system at Yucca Mountain is part of the Alkali Flat-Furnace Creek subbasin of the Death Valley groundwater basin. Variations in the gradients of the potentiometric surface provided the basis for subdividing the Yucca Mountain area into zones of: (1) large hydraulic gradient where potentiometric levels change at least 300 meters in a few kilometers; (2) moderate hydraulic gradient where potentiometric levels change about 45 meters in a few kilometers; and (3) small hydraulic gradient where potentiometric levels change only about 2 meters in several kilometers. Vertical hydraulic gradients were measured in only a few boreholes around Yucca Mountain; most boreholes had little change in potentiometric levels with depth. Limited hydraulic testing of boreholes in the Yucca Mountain area indicated that the range in transmissivity was more than 2 to 3 orders of magnitude in a particular hydrogeologic unit, and that the average values for the individual hydrogeologic units generally differed by about 1 order of magnitude. The upper volcanic aquifer seems to be the most permeable hydrogeologic unit, but this conclusion was based on exceedingly limited data

  19. Groundwater Capture Zones

    Data.gov (United States)

    Iowa State University GIS Support and Research Facility — Source water protection areas are delineated for each groundwater-based public water supply system using available geologic and hydrogeologic information to...

  20. Groundwater flow, nutrient, and stable isotope dynamics in the parafluvial-hyporheic zone of the regulated Lower Colorado River (Texas, USA) over the course of a small flood

    Science.gov (United States)

    Briody, Alyse C.; Cardenas, M. Bayani; Shuai, Pin; Knappett, Peter S. K.; Bennett, Philip C.

    2016-06-01

    Periodic releases from an upstream dam cause rapid stage fluctuations in the Lower Colorado River near Austin, Texas, USA. These daily pulses modulate fluid exchange and residence times in the hyporheic zone where biogeochemical reactions are typically pronounced. The effects of a small flood pulse under low-flow conditions on surface-water/groundwater exchange and biogeochemical processes were studied by monitoring and sampling from two dense transects of wells perpendicular to the river. The first transect recorded water levels and the second transect was used for water sample collection at three depths. Samples were collected from 12 wells every 2 h over a 24-h period which had a 16-cm flood pulse. Analyses included nutrients, carbon, major ions, and stable isotopes of water. The relatively small flood pulse did not cause significant mixing in the parafluvial zone. Under these conditions, the river and groundwater were decoupled, showed potentially minimal mixing at the interface, and did not exhibit any discernible denitrification of river-borne nitrate. The chemical patterns observed in the parafluvial zone can be explained by evaporation of groundwater with little mixing with river water. Thus, large pulses may be necessary in order for substantial hyporheic mixing and exchange to occur. The large regulated river under a low-flow and small flood pulse regime functioned mainly as a gaining river with little hydrologic connectivity beyond a narrow hyporheic zone.

  1. Groundwater and vadose Zone Integration Project Nuclear Material Mass Flow and Accountability on the Hanford Site

    International Nuclear Information System (INIS)

    GRASHER, A.A.

    2001-01-01

    The purpose of this report is to provide a discussion of the accountable inventory of Hanford Site nuclear material (NM) over the operating period. This report does not provide judgments on impacts to the Hanford Site environs by the reported waste streams or inventory. The focus of this report is on the processes, facilities, and process streams that constituted the flow primarily of plutonium and uranium through the Hanford Site. The material balance reports (MBRS) are the basis of the NM accountable inventory maintained by each of the various contractors used by the U.S. Department of Energy (DOE) and its predecessors to operate the Hanford Site. The inventory was tracked in terms of a starting inventory, receipts, transfers, and ending inventory. The various components of the inventory are discussed as well as the uncertainty in the measurement values used to establish plant inventory and material transfers. The accountable NM inventory does not report all the NM on the Hanford Site and this difference is discussed relative to some representative nuclides. The composition and location of the current accountable inventory are provided, as well as the latest approved set (2000) of flow diagrams of the proposed disposition of the excess accountable NM inventory listed on the Idaho National Engineering and Environmental Laboratory (INEEL) web page

  2. Simulations of groundwater flow and particle-tracking analysis in the zone of contribution to a public-supply well in San Antonio, Texas

    Science.gov (United States)

    Lindgren, Richard L.; Houston, Natalie A.; Musgrove, MaryLynn; Fahlquist, Lynne S.; Kauffman, Leon J.

    2011-01-01

    In 2006, a public-supply well in San Antonio, Texas, was selected for intensive study to assess the vulnerability of public-supply wells in the Edwards aquifer to contamination by a variety of compounds. A local-scale, steady-state, three-dimensional numerical groundwater-flow model was developed and used in this study to evaluate the movement of water and solutes from recharge areas to the selected public-supply well. Particle tracking was used to compute flow paths and advective traveltimes throughout the model area and to delineate the areas contributing recharge and zone of contribution for the selected public-supply well.

  3. Regional Survey of Structural Properties and Cementation Patterns of Fault Zones in the Northern Part of the Albuquerque Basin, New Mexico - Implications for Ground-Water Flow

    Science.gov (United States)

    Minor, Scott A.; Hudson, Mark R.

    2006-01-01

    Motivated by the need to document and evaluate the types and variability of fault zone properties that potentially affect aquifer systems in basins of the middle Rio Grande rift, we systematically characterized structural and cementation properties of exposed fault zones at 176 sites in the northern Albuquerque Basin. A statistical analysis of measurements and observations evaluated four aspects of the fault zones: (1) attitude and displacement, (2) cement, (3) lithology of the host rock or sediment, and (4) character and width of distinctive structural architectural components at the outcrop scale. Three structural architectural components of the fault zones were observed: (1) outer damage zones related to fault growth; these zones typically contain deformation bands, shear fractures, and open extensional fractures, which strike subparallel to the fault and may promote ground-water flow along the fault zone; (2) inner mixed zones composed of variably entrained, disrupted, and dismembered blocks of host sediment; and (3) central fault cores that accommodate most shear strain and in which persistent low- permeability clay-rich rocks likely impede the flow of water across the fault. The lithology of the host rock or sediment influences the structure of the fault zone and the width of its components. Different grain-size distributions and degrees of induration of the host materials produce differences in material strength that lead to variations in width, degree, and style of fracturing and other fault-related deformation. In addition, lithology of the host sediment appears to strongly control the distribution of cement in fault zones. Most faults strike north to north-northeast and dip 55? - 77? east or west, toward the basin center. Most faults exhibit normal slip, and many of these faults have been reactivated by normal-oblique and strike slip. Although measured fault displacements have a broad range, from 0.9 to 4,000 m, most are internal structure of, and cement

  4. Balancing practicality and hydrologic realism: a parsimonious approach for simulating rapid groundwater recharge via unsaturated-zone preferential flow

    Science.gov (United States)

    Mirus, Benjamin B.; Nimmo, J.R.

    2013-01-01

    The impact of preferential flow on recharge and contaminant transport poses a considerable challenge to water-resources management. Typical hydrologic models require extensive site characterization, but can underestimate fluxes when preferential flow is significant. A recently developed source-responsive model incorporates film-flow theory with conservation of mass to estimate unsaturated-zone preferential fluxes with readily available data. The term source-responsive describes the sensitivity of preferential flow in response to water availability at the source of input. We present the first rigorous tests of a parsimonious formulation for simulating water table fluctuations using two case studies, both in arid regions with thick unsaturated zones of fractured volcanic rock. Diffuse flow theory cannot adequately capture the observed water table responses at both sites; the source-responsive model is a viable alternative. We treat the active area fraction of preferential flow paths as a scaled function of water inputs at the land surface then calibrate the macropore density to fit observed water table rises. Unlike previous applications, we allow the characteristic film-flow velocity to vary, reflecting the lag time between source and deep water table responses. Analysis of model performance and parameter sensitivity for the two case studies underscores the importance of identifying thresholds for initiation of film flow in unsaturated rocks, and suggests that this parsimonious approach is potentially of great practical value.

  5. 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.

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

    Science.gov (United States)

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

    2016-09-01

    previous hypothesis that regional groundwater flow from the piedmont groundwater recharge zone predominantly discharges at the coastline may therefore be false. A more reliable alternative might be to conceptualize deep groundwater below the coastal plains a hydrodynamically stagnant zone, responding gradually to landscape and hydrological change on geologic timescales. This study brings a new and original understanding of the groundwater flow system in an important regional basin, in the context of its geometry and evolution over geological timescales. There are important implications for the sustainability of the ongoing high rates of groundwater extraction in the NCB.

  7. Approach for delineation of contributing areas and zones of transport to selected public-supply wells using a regional ground-water flow model, Palm Beach County, Florida

    Science.gov (United States)

    Renken, R.A.; Patterson, R.D.; Orzol, L.L.; Dixon, Joann

    2001-01-01

    Rapid urban development and population growth in Palm Beach County, Florida, have been accompanied with the need for additional freshwater withdrawals from the surficial aquifer system. To maintain water quality, County officials protect capture areas and determine zones of transport of municipal supply wells. A multistep process was used to help automate the delineation of wellhead protection areas. A modular ground-water flow model (MODFLOW) Telescopic Mesh Refinement program (MODTMR) was used to construct an embedded flow model and combined with particle tracking to delineate zones of transport to supply wells; model output was coupled with a geographic information system. An embedded flow MODFLOW model was constructed using input and output file data from a preexisting three-dimensional, calibrated model of the surficial aquifer system. Three graphical user interfaces for use with the geographic information software, ArcView, were developed to enhance the telescopic mesh refinement process. These interfaces include AvMODTMR for use with MODTMR; AvHDRD to build MODFLOW river and drain input files from dynamically segmented linear (canals) data sets; and AvWELL Refiner, an interface designed to examine and convert well coverage spatial data layers to a MODFLOW Well package input file. MODPATH (the U.S. Geological Survey particle-tracking postprocessing program) and MODTOOLS (the set of U.S. Geological Survey computer programs to translate MODFLOW and MODPATH output to a geographic information system) were used to map zones of transport. A steady-state, five-layer model of the Boca Raton area was created using the telescopic mesh refinement process and calibrated to average conditions during January 1989 to June 1990. A sensitivity analysis of various model parameters indicates that the model is most sensitive to changes in recharge rates, hydraulic conductivity for layer 1, and leakance for layers 3 and 4 (Biscayne aquifer). Recharge (58 percent); river (canal

  8. 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

  9. Site scale groundwater flow in Haestholmen

    International Nuclear Information System (INIS)

    Loefman, J.

    1999-05-01

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

  10. Actively heated high-resolution fiber-optic-distributed temperature sensing to quantify streambed flow dynamics in zones of strong groundwater upwelling

    Science.gov (United States)

    Briggs, Martin A.; Buckley, Sean F.; Bagtzoglou, Amvrossios C.; Werkema, Dale D.; Lane, John W.

    2016-01-01

    Zones of strong groundwater upwelling to streams enhance thermal stability and moderate thermal extremes, which is particularly important to aquatic ecosystems in a warming climate. Passive thermal tracer methods used to quantify vertical upwelling rates rely on downward conduction of surface temperature signals. However, moderate to high groundwater flux rates (>−1.5 m d−1) restrict downward propagation of diurnal temperature signals, and therefore the applicability of several passive thermal methods. Active streambed heating from within high-resolution fiber-optic temperature sensors (A-HRTS) has the potential to define multidimensional fluid-flux patterns below the extinction depth of surface thermal signals, allowing better quantification and separation of local and regional groundwater discharge. To demonstrate this concept, nine A-HRTS were emplaced vertically into the streambed in a grid with ∼0.40 m lateral spacing at a stream with strong upward vertical flux in Mashpee, Massachusetts, USA. Long-term (8–9 h) heating events were performed to confirm the dominance of vertical flow to the 0.6 m depth, well below the extinction of ambient diurnal signals. To quantify vertical flux, short-term heating events (28 min) were performed at each A-HRTS, and heat-pulse decay over vertical profiles was numerically modeled in radial two dimension (2-D) using SUTRA. Modeled flux values are similar to those obtained with seepage meters, Darcy methods, and analytical modeling of shallow diurnal signals. We also observed repeatable differential heating patterns along the length of vertically oriented sensors that may indicate sediment layering and hyporheic exchange superimposed on regional groundwater discharge.

  11. Monitoring probe for groundwater flow

    Science.gov (United States)

    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.

  12. On the development of a three-dimensional finite-element groundwater flow model of the saturated zone, Yucca Mountain, Nevada

    International Nuclear Information System (INIS)

    Czarnecki, J.B.; Faunt, C.C.; Gable, C.W.; Zyvoloski, G.A.

    1996-01-01

    Development of a preliminary three-dimensional model of the saturated zone at Yucca Mountain, the potential location for a high-level nuclear waste repository, is presented. The development of the model advances the technology of interfacing: (1)complex three-dimensional hydrogeologic framework modeling; (2) fully three-dimensional, unstructured, finite-element mesh generation; and (3) groundwater flow, heat, and transport simulation. The three-dimensional hydrogeologic framework model is developed using maps, cross sections, and well data. The framework model data are used to feed an automated mesh generator, designed to discretize irregular three-dimensional solids,a nd to assign materials properties from the hydrogeologic framework model to the tetrahedral elements. The mesh generator facilitated the addition of nodes to the finite-element mesh which correspond to the exact three-dimensional position of the potentiometric surface based on water-levels from wells. A ground water flow and heat simulator is run with the resulting finite- element mesh, within a parameter-estimation program. The application of the parameter-estimation program is designed to provide optimal values of permeability and specified fluxes over the model domain to minimize the residual between observed and simulated water levels

  13. Simulations of Ground-Water Flow and Particle Pathline Analysis in the Zone of Contribution of a Public-Supply Well in Modesto, Eastern San Joaquin Valley, California

    Science.gov (United States)

    Burow, Karen R.; Jurgens, Bryant C.; Kauffman, Leon J.; Phillips, Steven P.; Dalgish, Barbara A.; Shelton, Jennifer L.

    2008-01-01

    Shallow ground water in the eastern San Joaquin Valley is affected by high nitrate and uranium concentrations and frequent detections of pesticides and volatile organic compounds (VOC), as a result of ground-water development and intensive agricultural and urban land use. A single public-supply well was selected for intensive study to evaluate the dominant processes affecting the vulnerability of public-supply wells in the Modesto area. A network of 23 monitoring wells was installed, and water and sediment samples were collected within the approximate zone of contribution of the public-supply well, to support a detailed analysis of physical and chemical conditions and processes affecting the water chemistry in the well. A three-dimensional, steady-state local ground-water-flow and transport model was developed to evaluate the age of ground water reaching the well and to evaluate the vulnerability of the well to nonpoint source input of nitrate and uranium. Particle tracking was used to compute pathlines and advective travel times in the ground-water flow model. The simulated ages of particles reaching the public-supply well ranged from 9 to 30,000 years, with a median of 54 years. The age of the ground water contributed to the public-supply well increased with depth below the water table. Measured nitrate concentrations, derived primarily from agricultural fertilizer, were highest (17 milligrams per liter) in shallow ground water and decreased with depth to background concentrations of less than 2 milligrams per liter in the deepest wells. Because the movement of water is predominantly downward as a result of ground-water development, and because geochemical conditions are generally oxic, high nitrate concentrations in shallow ground water are expected to continue moving downward without significant attenuation. Simulated long-term nitrate concentrations indicate that concentrations have peaked and will decrease in the public-supply well during the next 100 years

  14. 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.

  15. 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

  16. Global scale groundwater flow model

    Science.gov (United States)

    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.

  17. 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

  18. 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

  19. Conceptual and numerical models of groundwater flow and solute transport in fracture zones: Application to the Aspo Island (Sweden); Modelos conceptuales y numericos de flujo y transporte de solutos en zonas de fractura: aplicacion a la isla de Aspo (Suecia)

    Energy Technology Data Exchange (ETDEWEB)

    Molinero, J.; Samper, J.

    2003-07-01

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

  20. 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

  1. Modeling groundwater flow and quality

    Science.gov (United States)

    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.

  2. Numerical modeling for saturated-zone groundwater travel time analysis at Yucca Mountain

    International Nuclear Information System (INIS)

    Arnold, B.W.; Barr, G.E.

    1996-01-01

    A three-dimensional, site-scale numerical model of groundwater flow in the saturated zone at Yucca Mountain was constructed and linked to particle tracking simulations to produce an estimate of the distribution of groundwater travel times from the potential repository to the boundary of the accessible environment. This effort and associated modeling of groundwater travel times in the unsaturated zone were undertaken to aid in the evaluation of compliance of the site with 10CFR960. These regulations stipulate that pre-waste-emplacement groundwater travel time to the accessible environment shall exceed 1,000 years along any path of likely and significant radionuclide travel

  3. A Groundwater Model to Assess Water Resource Impacts at the Brenda Solar Energy Zone

    Energy Technology Data Exchange (ETDEWEB)

    Quinn, John [Argonne National Lab. (ANL), Argonne, IL (United States); Carr, Adrianne E. [Argonne National Lab. (ANL), Argonne, IL (United States); Greer, Chris [Argonne National Lab. (ANL), Argonne, IL (United States); Bowen, Esther E. [Argonne National Lab. (ANL), Argonne, IL (United States)

    2013-12-01

    The purpose of this study is to develop a groundwater flow model to examine the influence of potential groundwater withdrawal to support utility-scale solar energy development at the Brenda Solar Energy Zone (SEZ), as a part of the Bureau of Land Management’s (BLM’s) Solar Energy Program.

  4. A Groundwater Model to Assess Water Resource Impacts at the Imperial East Solar Energy Zone

    Energy Technology Data Exchange (ETDEWEB)

    Quinn, John [Argonne National Lab. (ANL), Argonne, IL (United States); Greer, Chris [Argonne National Lab. (ANL), Argonne, IL (United States); O' Connor, Ben L. [Argonne National Lab. (ANL), Argonne, IL (United States); Tompson, Andrew F.B. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2013-12-01

    The purpose of this study is to develop a groundwater flow model to examine the influence of potential groundwater withdrawal to support the utility-scale solar energy development at the Imperial East Solar Energy Zone (SEZ) as a part of the Bureau of Land Management’s (BLM) solar energy program.

  5. Validation on groundwater flow model including sea level change. Modeling on groundwater flow in coastal granite area

    International Nuclear Information System (INIS)

    Hasegawa, Takuma; Miyakawa, Kimio

    2009-01-01

    It is important to verify the groundwater flow model that reproduces pressure head, water chemistry, and groundwater age. However, water chemistry and groundwater age are considered to be influenced by historical events. In this study, sea level change during glacial-interglacial cycle was taken into account for simulating salinity and groundwater age at coastal granite area. As a result of simulation, salinity movement could not catch up with sea level changes, and mixing zone was formed below the fresh-water zone. This mixing zone was observed in the field measurement, and the observed salinities were agreed with simulated results including sea level change. The simulated residence time including sea level change is one-tenth of steady state. The reason is that the saline water was washed out during regression and modern sea-water was infiltrated during transgression. As mentioned before, considering sea level change are important to reproduce salinity and helium age at coastal area. (author)

  6. 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

  7. Site-Scale Saturated Zone Flow Model

    International Nuclear Information System (INIS)

    G. Zyvoloski

    2003-01-01

    The purpose of this model report is to document the components of the site-scale saturated-zone flow model at Yucca Mountain, Nevada, in accordance with administrative procedure (AP)-SIII.lOQ, ''Models''. This report provides validation and confidence in the flow model that was developed for site recommendation (SR) and will be used to provide flow fields in support of the Total Systems Performance Assessment (TSPA) for the License Application. The output from this report provides the flow model used in the ''Site-Scale Saturated Zone Transport'', MDL-NBS-HS-000010 Rev 01 (BSC 2003 [162419]). The Site-Scale Saturated Zone Transport model then provides output to the SZ Transport Abstraction Model (BSC 2003 [164870]). In particular, the output from the SZ site-scale flow model is used to simulate the groundwater flow pathways and radionuclide transport to the accessible environment for use in the TSPA calculations. Since the development and calibration of the saturated-zone flow model, more data have been gathered for use in model validation and confidence building, including new water-level data from Nye County wells, single- and multiple-well hydraulic testing data, and new hydrochemistry data. In addition, a new hydrogeologic framework model (HFM), which incorporates Nye County wells lithology, also provides geologic data for corroboration and confidence in the flow model. The intended use of this work is to provide a flow model that generates flow fields to simulate radionuclide transport in saturated porous rock and alluvium under natural or forced gradient flow conditions. The flow model simulations are completed using the three-dimensional (3-D), finite-element, flow, heat, and transport computer code, FEHM Version (V) 2.20 (software tracking number (STN): 10086-2.20-00; LANL 2003 [161725]). Concurrently, process-level transport model and methodology for calculating radionuclide transport in the saturated zone at Yucca Mountain using FEHM V 2.20 are being

  8. 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

  9. 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

  10. Hydrological mediated denitrification in groundwater below a seasonal flooded restored riparian zone

    DEFF Research Database (Denmark)

    Jensen, Jannick Kolbjørn; Engesgaard, Peter; Johnsen, Anders R.

    2017-01-01

    nitrate removal in groundwater primarily by two mechanisms. First, by creating a stagnant flow zone beneath the flooded area thereby increasing the residence time and leaving more time for nitrate removal. Secondly, nitrate removal is increased by enhancing upward flow into the highly reactive organic......A restored riparian zone was characterized to understand the effects of flooding on subsurface hydrological flow paths and nitrate removal in groundwater. Field and laboratory investigations were combined with numerical modeling of dynamic flow and reactive nitrate transport. Flooding enhances...

  11. Radionuclides in groundwater flow system understanding

    Science.gov (United States)

    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

  12. Particle tracking for unsaturated-zone groundwater travel time analysis at Yucca Mountain

    International Nuclear Information System (INIS)

    Arnold, B.W.; Skinner, L.H.; Zieman, N.B.

    1995-01-01

    A particle tracking code developed to link numerical modeling of groundwater flow in the unsaturated zone to the analysis of groundwater travel times was used to produce preliminary estimates of the distribution of groundwater-travel time from a potential repository at Yucca Mountain, Nevada to the water table. Compliance with 10CFR960 requires the demonstration that pre-waste-emplacement groundwater travel time from the disturbed zone to the accessible environment is expected to exceed 1,000 years along any path of likely and significant radionuclide travel. The use of multiple particles and multiple realizations of the geology and parameter distributions in the unsaturated zone allows a probabilistic analysis of groundwater travel times that may be applied for evaluating compliance

  13. Patterns in groundwater chemistry resulting from groundwater flow

    Science.gov (United States)

    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

  14. SATURATED ZONE FLOW AND TRANSPORT MODEL ABSTRACTION

    International Nuclear Information System (INIS)

    B.W. ARNOLD

    2004-01-01

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

  15. 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

  16. 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

  17. Spatial variability analysis of combining the water quality and groundwater flow model to plan groundwater and surface water management in the Pingtung plain

    Science.gov (United States)

    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.

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

    OpenAIRE

    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...

  19. 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.)

  20. Interpretation of environmental isotopic groundwater data. Arid and semi-arid zones

    International Nuclear Information System (INIS)

    Geyh, M.A.

    1980-01-01

    Various hydrodynamic aspects are discussed in order to show their implication for the hydrogeological interpretation of environmental isotope and hydrochemical groundwater data. Special attention is drawn to radiocarbon and tritium studies carried out in arid and semi-arid zones. An exponential model has been utilized to determine the mean residence time of the long-term water from springs in karst and crystalline regions. Hydrogeological parameters such as the porosity can be checked by this result. In addition, the exponential model offers the possibility of determining the initial 14 C content of spring water, which is sensitively dependent on the soil of the recharge area. A base-flow model has been introduced to interpret the 14 C and 3 H data of groundwater samples from older karst regions. Differences between pumped and drawn samples exist with respect to the groundwater budget. Owing to pumping, the old base flow is accelerated and becomes enriched in pumped groundwater in comparison to the short-term water. Radiocarbon ages of groundwater in alluvium may be dubious because of isotope exchange with the CO 2 in the root zone along the river bank. Under confined conditions 14 C groundwater ages are diminished if the hydraulic head of the confined aquifer is lower than that of the shallow one. This is due to the radiocarbon downwards transport by convection of shallow groundwater. The same effect occurs, though much faster, if the groundwater table is depleted by groundwater withdrawal. The decrease of the radiocarbon groundwater ages in time can be used to determine the hydraulic transmissibility coefficient of the aquitarde. According to the practical and theoretic results obtained the hydrodynamic aspects require at least the same attention for the interpretation of environmental isotope and hydrochemical data of groundwater as do hydrochemical and isotope fractionation processes. (author)

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

    Science.gov (United States)

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

    2017-06-01

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

  2. An initial examination of tungsten geochemistry along groundwater flow paths

    Science.gov (United States)

    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

  3. Evaluating groundwater flow using passive electrical measurements

    Science.gov (United States)

    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.

  4. 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.)

  5. Submarine Groundwater Discharge in the Coastal Zone

    Science.gov (United States)

    Bakti, Hendra

    2018-02-01

    Indonesia is one of the archipelagic countries that has the longest coastline in the world. Because it is located in the tropics, in general it has a very high rainfall. Each island has a different morphology which is composed of a variety of rocks with different hydrogeological properties. This natural condition allows for the presence of groundwater in different amount in each island. The difference in groundwater hydraulics gradients in aquifer continuous to the sea has triggered the discharge of groundwater to offshore known as submarine groundwater discharge (SGD). Its presence can be as seepage or submarine springs with components derived from land and sea and a mixture between them. The understanding of SGD phenomenon is very important because it can be useful as a source of clean water in coastal areas, affecting marine health, and improving marine environment.

  6. 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.

  7. Heat and Groundwater Flow in the San Gabriel Mountains, California

    Science.gov (United States)

    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

  8. Isotope Investigations of Groundwater Movement in a Coarse Gravel Unsaturated Zone

    Energy Technology Data Exchange (ETDEWEB)

    Mali, N. [Geological Survey of Slovenia, Department of Hydrogeology, Ljubljana (Slovenia); Kozar-Logar, J. [Jozef Stefan Institute, Ljubljana (Slovenia); Leis, A. [Institute of Water Resources Management, Hydrogeology and Geophysics, Joanneum Research Forschungsgesellschaft mbH, Graz (Austria)

    2013-07-15

    The unsaturated zone above an aquifer serves as a water reservoir which discharges water and possible pollution to the saturated zone. This paper presents the application of oxygen-18 and tritium isotope methods in the study of groundwater transport processes in the unsaturated zone of Selniska Dobrava coarse gravel aquifer. The Selniska Dobrava gravel aquifer is an important water resource for Maribor and its surroundings, therefore the determination of transport processes in the unsaturated zone is important regarding its protection. Groundwater flow characteristics were estimated using isotopes and based on experimental work in a lysimeter. Tritium investigation results were compared with the results of long term oxygen-18 isotope investigation. In this paper the analytical approach, results and interpretation of {delta}{sup 18}O and tritium measurements in the unsaturated zone are presented. (author)

  9. Regression modeling of ground-water flow

    Science.gov (United States)

    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)

  10. Quantification of groundwater recharge through application of pilot techniques in the unsaturated zone.

    Science.gov (United States)

    Kallioras, Andreas; Piepenbrink, Matthias; Schuth, Christoph; Pfletschinger, Heike; Dietrich, Peter; Koeniger, Franz; Rausch, Randolf

    2010-05-01

    times as well as preferential flow paths through the unsaturated zone. The synthesis of all the aforementioned methods, is expected to result to the accurate quantification of groundwater recharge in space and time through the unsaturated zone. ACKNOWLEDGMENTS The authors would like to acknowledge the cooperation between Technical University of Darmstadt (Germany), Helmholtz-Centre for Environmental Research-UFZ (Leipzig, Germany), GTZ-IS (Riyadh Offices, Saudi Arabia) and the Ministry of Water and Electricity-MoWE, Kingdom of Saudi Arabia. Funding is provided by the German Ministry of Education and Research (BMBF) through the research program IWAS (http://www.iwas-sachsen.ufz.de/).

  11. 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

  12. 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.

  13. Underground mining of the lower 163 zone through groundwater drainage at the Eagle Point Mine

    International Nuclear Information System (INIS)

    Robson, D.M.; Bashir, R.; Thomson, J.; Klemmer, S.; Rigden, A.

    2010-01-01

    The Eagle Point Mine is part of the Cameco Rabbit Lake Operation. The mine produces uranium ore using the long-hole, vertical and horizontal retreat mining method. The majority of the mine workings are under Wollaston Lake and cementitious grouting is used as one of the water control measures. Historical groundwater table in the mining area was close to ground surface. The Lower 163 Zone encompasses an estimated 4.2 million pounds U_3O_8 geological resource that was not considered feasible to mine due to the expected groundwater flows in the area. Cross-hole testing was conducted to better understand the groundwater flow through various geologic units. A local depressurization test was conducted to assess the potential for lowering the water table. Following testing an active depressurization was conducted to lower the groundwater table below the planned mining areas. This resulted in safe and drier mining conditions and allowed for the successful extraction of the ore body. (author)

  14. Detect groundwater flowing from riverbed using a drone

    Science.gov (United States)

    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

  15. Geomorphic aspects of groundwater flow

    Science.gov (United States)

    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

  16. 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

  17. Understanding large scale groundwater flow in fractured crystalline rocks to aid in repository siting

    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)

  18. Identification of groundwater prospective zones by using remote ...

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Earth System Science; Volume 114; Issue 5. Identification of groundwater prospective zones by using remote sensing and geoelectrical methods in Jharia and Raniganj coalfields, Dhanbad district, Jharkhand state. Basudeo Rai A Tiwari V S Dubey. Volume 114 Issue 5 October 2005 pp 515-522 ...

  19. 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.

  20. Groundwater Flow Model of the General Separations Area Using PORFLOW

    International Nuclear Information System (INIS)

    FLACH, GREGORY

    2004-01-01

    The E Area PA (McDowell-Boyer et al. 2000) includes a steady-state simulation of groundwater flow in the General Separations Area as a prerequisite for saturated zone contaminant transport analyses. The groundwater flow simulations are based on the FACT code (Hamm and Aleman2000). The FACT-based GSA model was selected during preparation of the original PA to take advantage of an existing model developed for environmental restoration applications at the SRS (Flach and Harris 1997, 1999; Flach 1999). The existing GSA/FACT model was then slightly modified for PA use, as described in the PA document. FACT is a finite-element code utilizing deformed brick elements. Material properties are defined at element centers, and state variables such as hydraulic head are located at element vertices. The PORFLOW code (Analytic and Computational Research, Inc. 2000) was selected for performing saturated zone transport simulations of source zone radionuclides and their progeny. PORFLOW utilizes control volume discretization and the nodal point integration method, with all properties and state variables being defined at the center of an interior grid cell. The groundwater flow calculation includes translating the Darcy velocity field computed by FACT into a form compatible for input to PORFLOW. The FACT velocity field is defined at element vertices, whereas PORFLOW requires flux across cell faces. For the present PA, PORFLOW cell face flux is computed in a two-step process. An initial face flux is computed from FACT as an average of the normal components of Darcy velocity at the four corners. The derived flux field approximately conserves mass, but not rigorously. Thus, the flux field is subsequently perturbed to force rigorous mass conservation on a cell-by-cell basis. The undocumented process used is non-unique and can introduce significant artifacts into the final flux field

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

    International Nuclear Information System (INIS)

    Hasegawa, Takuma; Tanaka, Yasuharu

    2004-01-01

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

  2. Using 14C and 3H to understand groundwater flow and recharge in an aquifer window

    Science.gov (United States)

    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

  3. Determination of protection zones for Dutch groundwater wells against virus contamination--uncertainty and sensitivity analysis.

    Science.gov (United States)

    Schijven, J F; Mülschlegel, J H C; Hassanizadeh, S M; Teunis, P F M; de Roda Husman, A M

    2006-09-01

    Protection zones of shallow unconfined aquifers in The Netherlands were calculated that allow protection against virus contamination to the level that the infection risk of 10(-4) per person per year is not exceeded with a 95% certainty. An uncertainty and a sensitivity analysis of the calculated protection zones were included. It was concluded that protection zones of 1 to 2 years travel time (206-418 m) are needed (6 to 12 times the currently applied travel time of 60 days). This will lead to enlargement of protection zones, encompassing 110 unconfined groundwater well systems that produce 3 x 10(8) m3 y(-1) of drinking water (38% of total Dutch production from groundwater). A smaller protection zone is possible if it can be shown that an aquifer has properties that lead to greater reduction of virus contamination, like more attachment. Deeper aquifers beneath aquitards of at least 2 years of vertical travel time are adequately protected because vertical flow in the aquitards is only 0.7 m per year. The most sensitive parameters are virus attachment and inactivation. The next most sensitive parameters are grain size of the sand, abstraction rate of groundwater, virus concentrations in raw sewage and consumption of unboiled drinking water. Research is recommended on additional protection by attachment and under unsaturated conditions.

  4. Groundwater/Vadose Zone Integration Project Management Plan

    International Nuclear Information System (INIS)

    Hughes, M. C.

    1999-01-01

    This Project Management Plan (PMP) defines the authorities, roles, and responsibilities of the US Department of Energy (DOE), Richland Operations Office (RL) and those contractor organizations participating in the Hanford Site' s Groundwater/Vadose Zone (GW/VZ) Integration Project. The PMP also describes the planning and control systems, business processes, and other management tools needed to properly and consistently conduct the Integration Project scope of work

  5. The `Henry Problem' of `density-driven' groundwater flow versus Tothian `groundwater flow systems' with variable density: A review of the influential Biscayne aquifer data.

    Science.gov (United States)

    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

  6. Prediction of Groundwater Quality Improvement Down-Gradient of In Situ Permeable Treatment Barriers and Fully-Remediated Source Zones. ESTCP Cost and Performance Report

    National Research Council Canada - National Science Library

    Johnson, Paul C; Carlson, Pamela M; Dahlen, Paul

    2008-01-01

    In situ permeable treatment barriers (PTB) are designed so that contaminated groundwater flows through an engineered treatment zone within which contaminants are eliminated or the concentrations are significantly reduced...

  7. An analytical study on groundwater flow in drainage basins with horizontal wells

    Science.gov (United States)

    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.

  8. Assessment of groundwater recharge potential zone using GIS approach in Purworejo regency, Central Java province, Indonesia

    Science.gov (United States)

    Aryanto, Daniel Eko; Hardiman, Gagoek

    2018-02-01

    Floods and droughts in Purworejo regency are an indication of problems in groundwater management. The current development progress has led to land conversion which has an impact on the problem of water infiltration in Purworejo regency. This study aims to determine the distribution of groundwater recharge potential zones by using geographic information system as the basis for ground water management. The groundwater recharge potential zone is obtained by overlaying all the thematic maps that affect the groundwater infiltration. Each thematic map is weighted according to its effect on groundwater infiltration such as land-use - 25%, rainfall - 20%, litology - 20%, soil - 15%, slope - 10%, lineament - 5%, and river density - 5% to find groundwater recharge potential zones. The groundwater recharge potential zones thus obtained were divided into five categories, viz., very high, high, medium, low and very low zones. The results of this study may be useful for better groundwater planning and management.

  9. 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...

  10. 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

  11. 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

  12. Sensitivity studies of unsaturated groundwater flow modeling for groundwater travel time calculations at Yucca Mountain, Nevada

    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

  13. Comment on "Evaluating interactions between groundwater and vadose zone using the HYDRUS-based flow package for MODFLOW" by Navin Kumar C. Twarakavi, Jirka Šimůnek and Sophia Seo

    Science.gov (United States)

    Niswonger, R.G.; Prudic, David E.

    2009-01-01

    Twarakavi et al (2008) compared four packages that can be used to estimate recharge for regional-scale groundwater flow simulations using MODFLOW (Harbaugh, 2005). This comment is focused on the comparisons made between two of these packages, namely, UZF1 (Niswonger et al., 2006) and a derivative of HYDRUS referred to herein as HYDRUS (Seo et al., 2007). In their paper, Twarakavi et al. (2008) stated that HYDRUS more accurately simulates unsaturated flow processes and groundwater recharge as compared to UZF1. However, Twarakavi et al. (2008) did not address several important differences between these models that undermine the advantages of HYDRUS as compared to UZF1 for simulating recharge. These differences were not revealed by the comparisons presented by Twarakavi et al. because the test simulations used to compare the models were too simple

  14. Heterogeneous hyporheic zone dechlorination of a TCE groundwater plume discharging to an urban river reach.

    Science.gov (United States)

    Freitas, Juliana G; Rivett, Michael O; Roche, Rachel S; Durrant Neé Cleverly, Megan; Walker, Caroline; Tellam, John H

    2015-02-01

    The typically elevated natural attenuation capacity of riverbed-hyporheic zones is expected to decrease chlorinated hydrocarbon (CHC) groundwater plume discharges to river receptors through dechlorination reactions. The aim of this study was to assess physico-chemical processes controlling field-scale variation in riverbed-hyporheic zone dechlorination of a TCE groundwater plume discharge to an urban river reach. The 50-m long pool-riffle-glide reach of the River Tame in Birmingham (UK) studied is a heterogeneous high energy river environment. The shallow riverbed was instrumented with a detailed network of multilevel samplers. Freeze coring revealed a geologically heterogeneous and poorly sorted riverbed. A chlorine number reduction approach provided a quantitative indicator of CHC dechlorination. Three sub-reaches of contrasting behaviour were identified. Greatest dechlorination occurred in the riffle sub-reach that was characterised by hyporheic zone flows, moderate sulphate concentrations and pH, anaerobic conditions, low iron, but elevated manganese concentrations with evidence of sulphate reduction. Transient hyporheic zone flows allowing input to varying riverbed depths of organic matter are anticipated to be a key control. The glide sub-reach displayed negligible dechlorination attributed to the predominant groundwater baseflow discharge condition, absence of hyporheic zone, transition to more oxic conditions and elevated sulphate concentrations expected to locally inhibit dechlorination. The tail-of-pool-riffle sub-reach exhibited patchy dechlorination that was attributed to sub-reach complexities including significant flow bypass of a low permeability, high organic matter, silty unit of high dechlorination potential. A process-based conceptual model of reach-scale dechlorination variability was developed. Key findings of practitioner relevance were: riverbed-hyporheic zone CHC dechlorination may provide only a partial, somewhat patchy barrier to CHC

  15. Analysis on groundwater evolution and interlayer oxidation zone position at the southern margin of Yilin basin

    International Nuclear Information System (INIS)

    Zhang Guanghui

    2007-01-01

    This paper discusses the development and evolution history of groundwater and its reworking to the interlayer oxidation zone, hydrogeochemical zonation of interlayer oxidation zone, mechanism of water-rock interaction and transportation pattern of uranium in the water in Yili Basin. It is suggested that groundwater is one of the important factors to control the development of interlayer oxidation zone and uranium mineralization. (authors)

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

    Science.gov (United States)

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

    2017-12-01

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

  17. 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

  18. Unsaturated zone flow modeling for GWTT-95

    International Nuclear Information System (INIS)

    Ho, C.K.; Altman, S.J.; McKenna, S.A.; Arnold, B.W.

    1995-01-01

    In accordance with the Nuclear Regulatory Commission regulation regarding groundwater travel times at geologic repositories, various models of unsaturated flow in fractured tuff have been developed and implemented to assess groundwater travel times at the potential repository at Yucca Mountain, Nevada. Kaplan used one-dimensional models to describe the uncertainty and sensitivity of travel times to various processes at Yucca Mountain. Robey and Arnold et al. used a two-dimensional equivalent continuum model (ECM) with inter- and intra-unit heterogeneity in an attempt to assess fast-flow paths through the unsaturated, fractured tuff at Yucca Mountain (GWTT-94). However, significant flow through the fractures in previous models was not simulated due to the characteristics of the ECM, which requires the matrix to be nearly saturated before flow through the fractures is initiated. In the current study (GWTT-95), four two-dimensional cross-sections at Yucca Mountain are simulated using both the ECM and dual-permeability (DK) models. The properties of both the fracture and matrix domains are geostatistically simulated, yielding completely heterogeneous continua. Then, simulations of flow through the four cross-sections are performed using spatially nonuniform infiltration boundary conditions. Steady-state groundwater travel times from the potential repository to the water table are calculated

  19. The 2016 groundwater flow model for Dane County, Wisconsin

    Science.gov (United States)

    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

  20. Groundwater Hydrochemical Zoning in Inland Plains and its Genetic Mechanisms

    Directory of Open Access Journals (Sweden)

    Liting Xing

    2018-06-01

    Full Text Available Pore water in inland plain areas, generally having poor water quality, contain complex hydrochemical properties. In order to examine groundwater chemical composition formation characteristics, groundwater in the Jiyang area of Lubei Plain was studied using stratified monitoring of drilling, analysis of water level and water quality, isotope analysis, ion ratio coefficient and isothermal adsorption experiments, hydrochemical characteristics, and analysis of variations in different shallow depths. Results show that: (1 Numerous hydrochemistry types are present in the diving. Along with the direction of groundwater flow, total dissolved solids (TDS of diving in the study area generally increases and the hydrochemical type changes from the HCO3 type to the HCO3·SO4 type, Cl·HCO3 type and the Cl·SO4 type. (2 Shallow brackish water and freshwater in the horizontal direction are alternately distributed, and shallow brackish water is distributed in the area between old channels, showing sporadic spots or bands, whose hydrochemistry type is predominantly Cl·SO4-Na·Mg·Ca. (3 Affected by the sedimentary environment, hydrodynamic conditions and other factors; diving, middle brackish water and deep freshwater are vertically deposited in the study area. The dynamics of middle brackish water quality are stable due to the sedimentary environment and clay deposits. The hydrochemistry types of middle brackish water are mainly Cl·SO4-Mg·Na and SO4·Cl-Na·Mg, while the deep confined water is dominated by HCO3. (4 The optimal adsorption isotherms of Na+, Ca2+ and Mg2+ in groundwater from clay, with a thickness raging from 6–112 m, conformed to the Henry equation and the Langmuir equation. The retardation of Na+, Ca2+ and Mg2+ in groundwater differed with differing depths of the clay deposit. The trend of change in retardation strength correlates strongly with the TDS of groundwater. Groundwater in the inland plain area is affected by complicated

  1. Structural Controls on Groundwater Flow in Basement Terrains: Geophysical, Remote Sensing, and Field Investigations in Sinai

    KAUST Repository

    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

  2. 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

  3. 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

  4. 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

  5. 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

  6. 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)

  7. 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

  8. Flow and transport in Riparian Zones

    DEFF Research Database (Denmark)

    Jensen, Jannick Kolbjørn

    scenarios with changing conditions for flow (steady state with no flooding or transient with flooding), hydrogeology, denitrification rate, and extent of flooding it is demonstrated how flow paths, residence times, and nitrate removal are affected. With this previous conceptual models on the hydrology......The PhD study presents research results from two re-established Danish riparian zones, Brynemade and Skallebanke, located along Odense River on the island Funen, Denmark. The overall objectives of the PhD study have been to improve the understanding of flow and transport in riparian zones....... The methodology focuses on; construction of field sites along Odense River, understanding flow and transport, and performing numerical/analytical model assessments of flow and transport. An initial 2D simulation study was performed with a conceptual setup based on the Brynemade site. Through a series of 2D model...

  9. Coastal Zone Hazards Related to Groundwater-Surface Water Interactions and Groundwater Flooding

    Science.gov (United States)

    Kontar, Y. A.; Ozorovich, Y. R.; Salokhiddinov, A. T.

    2009-12-01

    Worldwide, as many as half a million people have died in natural and man-made disasters since the turn of the 21st century (Wirtz, 2008). Further, natural and man-made hazards can lead to extreme financial losses (Elsner et al, 2009). Hazards, hydrological and geophysical risk analysis related to groundwater-surface water interactions and groundwater flooding have been to a large extent under-emphasized for coastal zone applications either due to economical limitations or underestimation of its significance. This is particularly true for tsunamis creating salt water intrusion to coastal aquifers, even though most tsunami hazard assessments have in the past relied on scenario or deterministic type models (Geist and Parsons, 2006), and to increasing mineralization of potable water because of intensive water diversions and also the abundance of highly toxic pollutants (mainly pesticides) in water, air and food, which contribute to the deterioration of the coastal population's health (Glantz, 2007). In the wake of pressing environmental and economic issues, it is of prime importance for the scientific community to shed light onto the great efforts by hydrologists and geophysicists to quantify conceptual uncertainties and to provide quality assurances of potential coastal zone hazard evaluation and prediction. This paper proposes consideration of two case studies which are important and significant for future development and essential for feasibility studies of hazards in the coastal zone. The territory of the Aral Sea Region in Central Asia is known as an ecological disaster coastal zone (Zavialov, 2005). It is now obvious that, in order to provide reasonable living conditions to the coastal zone population, it is first of all necessary to drastically improve the quality of the water dedicated to human needs. Due to their intensive pollution by industrial wastes and by drainage waters from irrigated fields, the Syr Darya and Amu Darya rivers can no longer be considered

  10. 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

  11. Regional groundwater modeling of the saturated zone in the vicinity of Yucca Mountain, Nevada

    International Nuclear Information System (INIS)

    Ahola, M.; Sagar, B.

    1992-10-01

    Results of groundwater modeling of the saturated zone in the vicinity of Yucca Mountain are presented. Both a regional (200 x 200 km) and subregional (50 x 50 km) model were used in the analyses. Simulations were conducted to determine the impact of various disruptive that might take place over the life span of a proposed Yucca Mountain geologic conditions repository on the groundwater flow field, as well as changes in the water-table elevations. These conditions included increases in precipitation and groundwater recharge within the regional model, changes in permeability of existing hydrogeologic barriers, a:nd the vertical intrusion of volcanic dikes at various orientations through the saturated zone. Based on the regional analysis, the rise in the water-table under Yucca Mountain due to various postulated conditions ranged from only a few meters to 275 meters. Results of the subregional model analysis, which was used to simulate intrusive dikes approximately 4 kilometers in length in the vicinity of Yucca Mountain, showed water-table rises ranging from a few meters to as much as 103 meters. Dikes oriented approximately north-south beneath Yucca Mountain produced the highest water-table rises. The conclusions drawn from this analysis are likely to change as more site-specific data become available and as the assumptions in the model are improved

  12. 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)

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

    Science.gov (United States)

    Belcher, Wayne R.; Sweetkind, Donald S.

    2010-01-01

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

  14. 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)

  15. Investigating riparian groundwater flow close to a losing river using diurnal temperature oscillations at high vertical resolution

    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

  16. Interpreting Repeated Temperature-Depth Profiles for Groundwater Flow

    NARCIS (Netherlands)

    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

  17. 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).

  18. 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 ...

  19. Death Valley regional ground-water flow system, Nevada and California -- hydrogeologic framework and transient ground-water flow model

    Science.gov (United States)

    Belcher, Wayne R.

    2004-01-01

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

  20. 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.

  1. Modeling Groundwater Flow System of a Drainage Basin in the Basement Complex Environment of Southwestern Nigera

    Science.gov (United States)

    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.

  2. 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.

  3. Redox zonation for different groundwater flow paths during bank filtration: a case study at Liao River, Shenyang, northeastern China

    Science.gov (United States)

    Su, Xiaosi; Lu, Shuai; Yuan, Wenzhen; Woo, Nam Chil; Dai, Zhenxue; Dong, Weihong; Du, Shanghai; Zhang, Xinyue

    2018-03-01

    The spatial and temporal distribution of redox zones in an aquifer is important when designing groundwater supply systems. Redox zonation can have direct or indirect control of the biological and chemical reactions and mobility of pollutants. In this study, redox conditions are characterized by interpreting the hydrogeological conditions and water chemistry in groundwater during bank infiltration at a site in Shenyang, northeast China. The relevant redox processes and zonal differences in a shallow flow path and deeper flow path at the field scale were revealed by monitoring the redox parameters and chemistry of groundwater near the Liao River. The results show obvious horizontal and vertical components of redox zones during bank filtration. Variations in the horizontal extent of the redox zone were controlled by the different permeabilities of the riverbed sediments and aquifer with depth. Horizontally, the redox zone was situated within 17 m of the riverbank for the shallow flow path and within 200 m for the deep flow path. The vertical extent of the redox zone was affected by precipitation and seasonal river floods and extended to 10 m below the surface. During bank filtration, iron and manganese oxides or hydroxides were reductively dissolved, and arsenic that was adsorbed onto the medium surface or coprecipitated is released into the groundwater. This leads to increased arsenic content in groundwater, which poses a serious threat to water supply security.

  4. 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

  5. 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.)

  6. 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

  7. 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

  8. 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.)

  9. Relation of streams, lakes, and wetlands to groundwater flow systems

    Science.gov (United States)

    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

  10. 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.)

  11. Estimating the dynamics of groundwater input into the coastal zone via continuous radon-222 measurements

    International Nuclear Information System (INIS)

    Burnett, William C.; Dulaiova, Henrieta

    2003-01-01

    Submarine groundwater discharge (SGD) into the coastal zone has received increased attention in the last few years as it is now recognized that this process represents an important pathway for material transport. Assessing these material fluxes is difficult, as there is no simple means to gauge the water flux. To meet this challenge, we have explored the use of a continuous radon monitor to measure radon concentrations in coastal zone waters over time periods from hours to days. Changes in the radon inventories over time can be converted to fluxes after one makes allowances for tidal effects, losses to the atmosphere, and mixing with offshore waters. If one assumes that advective flow of radon-enriched groundwater (pore waters) represent the main input of 222 Rn in the coastal zone, the calculated radon fluxes may be converted to water fluxes by dividing by the estimated or measured 222 Rn pore water activity. We have also used short-lived radium isotopes ( 223 Ra and 224 Ra) to assess mixing between near-shore and offshore waters in the manner pioneered by . During an experiment in the coastal Gulf of Mexico, we showed that the mixing loss derived from the 223 Ra gradient agreed very favorably to the estimated range based on the calculated radon fluxes. This allowed an independent constraint on the mixing loss of radon--an important parameter in the mass balance approach. Groundwater discharge was also estimated independently by the radium isotopic approach and was within a factor of two of that determined by the continuous radon measurements and an automated seepage meter deployed at the same site

  12. Arid-zone groundwater recharge and palaeorecharge: insights from the radioisotope chlorine-36

    International Nuclear Information System (INIS)

    Jacobson, G.; Wischusen, J.; Cresswell, R.; Fifield, K.

    1998-01-01

    AGSO's collaborative 'Western water' study of groundwater resources in Aboriginal lands in the southwest Northern Territory arid zone, has applied the radioisotope 36 CI and 14 C to investigate the sustainability of community water supplies drawn from shallow aquifers in the Papunya-Kintore-Yuendumu area. The 36 CI results have important implications for groundwater management throughout the arid zone, because substantial recharge occurs only during favourable, wet, interglacial climatic regimes. this has important implications for groundwater management in this area and elsewhere in central Australia, where most of the community water supplies depend on 'old' stored groundwater

  13. Aquifers and hyporheic zones: Towards an ecological understanding of groundwater

    Science.gov (United States)

    Hancock, Peter J.; Boulton, Andrew J.; Humphreys, William F.

    2005-03-01

    Ecological constraints in subsurface environments relate directly to groundwater flow, hydraulic conductivity, interstitial biogeochemistry, pore size, and hydrological linkages to adjacent aquifers and surface ecosystems. Groundwater ecology has evolved from a science describing the unique subterranean biota to its current form emphasising multidisciplinary studies that integrate hydrogeology and ecology. This multidisciplinary approach seeks to elucidate the function of groundwater ecosystems and their roles in maintaining subterranean and surface water quality. In aquifer-surface water ecotones, geochemical gradients and microbial biofilms mediate transformations of water chemistry. Subsurface fauna (stygofauna) graze biofilms, alter interstitial pore size through their movement, and physically transport material through the groundwater environment. Further, changes in their populations provide signals of declining water quality. Better integrating groundwater ecology, biogeochemistry, and hydrogeology will significantly advance our understanding of subterranean ecosystems, especially in terms of bioremediation of contaminated groundwaters, maintenance or improvement of surface water quality in groundwater-dependent ecosystems, and improved protection of groundwater habitats during the extraction of natural resources. Overall, this will lead to a better understanding of the implications of groundwater hydrology and aquifer geology to distributions of subsurface fauna and microbiota, ecological processes such as carbon cycling, and sustainable groundwater management. Les contraintes écologiques dans les environnements de subsurface sont en relation directe avec les écoulements des eaux souterraines, la conductivité hydraulique, la biogéochimie des milieux interstitiels, la taille des pores, et les liens hydrologiques avec les aquifères et les écosystèmes adjacents. L'écologie des eaux souterraines a évolué d'une science décrivant uniquement les

  14. 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.

  15. 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

  16. Boundary delineation for regional groundwater flow through geographic information system (Contract research)

    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)

  17. 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...

  18. 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

  19. 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

  20. Groundwater Recharge and Flow Regime revealed by multi-tracers approach in a headwater, North China Plain

    Science.gov (United States)

    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.

  1. 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

  2. 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

  3. Comparison of groundwater residence time using isotope techniques and numerical groundwater flow model in Gneissic Terrain, Korea

    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

  4. 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.

  5. 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 ...

  6. 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

  7. Stratabound pathways of preferred groundwater flow: An example from the Copper Ridge Dolomite in East Tennessee

    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

  8. Rare Earth Element Concentrations and Fractionation Patterns Along Groundwater Flow Paths in Two Different Aquifer Types (i.e., Sand vs. Carbonate)

    Science.gov (United States)

    Johannesson, K. H.; Tang, J.

    2003-12-01

    Groundwater samples were collected in two different types of aquifer (i.e., Carrizo Sand Aquifer, Texas and Upper Floridan carbonate Aquifer, west-central Florida) to study the concentrations, fractionation, and speciation of rare earth elements (REE) along groundwater flow paths in each aquifer. Major solutes and dissolved organic carbon (DOC) were also measured in these groundwaters. The Carrizo Sand aquifer was sampled in October 2002 and June 2003, whereas, to date, we have only sampled the Floridan once (i.e., June 2003). The data reveal no significant seasonal differences in major solute and REE concentrations for the Carrizo. In Carrizo sand aquifer, groundwaters from relatively shallow wells (i.e., less than 167 m) in the recharge zone are chiefly Ca-Na-HCO3-Cl type waters. With flow down-gradient the groundwaters shift composition to the Na-HCO3 waters. pH and alkalinity initially decrease with flow away from the recharge zone before increasing again down-gradient. DOC is generally low (0.65 mg/L) along the flow path. REE concentrations are highest in groundwaters from the recharge zone (Nd 40.5 pmol/kg), and decrease substantially with flow down-gradient reaching relatively low and stable values (Nd 4.1-8.6 pmol/kg) roughly 10 km from the recharge zone. Generally, Carrizo groundwaters exhibit HREE-enriched shale-normalized patterns. The HREE enrichments are especially strong for waters from the recharge zone [(Yb/Nd)SN =1.7-5.6], whereas down-gradient (deep) groundwaters have flatter patterns [(Yb/Nd)SN =0.7-2.5]. All groundwaters have slightly positive Eu anomalies (Eu/Eu* 0.09-0.14) and negative Ce anomalies (Ce/Ce* -0.85 - -0.07). In the Upper Floridan Aquifer, Ca, Mg, SO4, and Cl concentrations generally increase along groundwater flow path, whereas pH and alkalinity generally decrease. DOC is higher (0.64 - 2.29 mg/L) than in the Carrizo and initially increases along the flow path and then decreases down-gradient. LREE (Nd) concentrations generally

  9. Identifying three-dimensional nested groundwater flow systems in a Tóthian basin

    Science.gov (United States)

    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.

  10. Mapping of groundwater potential zones in the musi basin using remote sensing data and gis

    NARCIS (Netherlands)

    Ganapuram, Sreedhar; Vijaya Kumar, G.T.; Murali Krishna, I.V.; Kahya, Ercan; Demirel, M.C.

    2009-01-01

    The objective of this study is to explore the groundwater availability for agriculture in the Musi basin. Remote sensing data and geographic information system were used to locate potential zones for groundwater in the Musi basin. Various maps (i.e., base, hydrogeomorphological, geological,

  11. Climate reconstruction from borehole temperatures influenced by groundwater flow

    Science.gov (United States)

    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

  12. A Guide for Using the Transient Ground-Water Flow Model of the Death Valley Regional Ground-Water Flow System, Nevada and California

    Energy Technology Data Exchange (ETDEWEB)

    Joan B. Blainey; Claudia C. Faunt, and Mary C. Hill

    2006-05-16

    This report is a guide for executing numerical simulations with the transient ground-water flow model of the Death Valley regional ground-water flow system, Nevada and California using the U.S. Geological Survey modular finite-difference ground-water flow model, MODFLOW-2000. Model inputs, including observations of hydraulic head, discharge, and boundary flows, are summarized. Modification of the DVRFS transient ground-water model is discussed for two common uses of the Death Valley regional ground-water flow system model: predictive pumping scenarios that extend beyond the end of the model simulation period (1998), and model simulations with only steady-state conditions.

  13. Slow and preferential flow in the unsaturated zone and its impact on stable isotope composition

    International Nuclear Information System (INIS)

    Seiler, K.P.

    2001-01-01

    Stable isotope methods (δ 18 O and δ 2 H) have been used investigate the importance of bypass flow in the unsaturated zone which leads to unproductive water loss during flood irrigation. Field experiments have been carried out in Jordan and Pakistan in order to determine the occurrence of bypass flow, its amount and its velocity compared to piston flow. Results show that there is not only an advective component of flow (bypass flow) but a diffusive tracer exchange between piston and bypass flow. Infiltration calculations and analysis of tracer distributions are used to show that at the research sites, bypass flow amounts to about 25% of water recharged during winter. This estimate is important as it provides an assessment of the amount of water that passes the root zone and directly recharges groundwater. (author)

  14. An Update of the Analytical Groundwater Modeling to Assess Water Resource Impacts at the Afton Solar Energy Zone

    Energy Technology Data Exchange (ETDEWEB)

    Quinn, John J. [Argonne National Lab. (ANL), Argonne, IL (United States); Greer, Christopher B. [Argonne National Lab. (ANL), Argonne, IL (United States); Carr, Adrianne E. [Argonne National Lab. (ANL), Argonne, IL (United States)

    2014-10-01

    The purpose of this study is to update a one-dimensional analytical groundwater flow model to examine the influence of potential groundwater withdrawal in support of utility-scale solar energy development at the Afton Solar Energy Zone (SEZ) as a part of the Bureau of Land Management’s (BLM’s) Solar Energy Program. This report describes the modeling for assessing the drawdown associated with SEZ groundwater pumping rates for a 20-year duration considering three categories of water demand (high, medium, and low) based on technology-specific considerations. The 2012 modeling effort published in the Final Programmatic Environmental Impact Statement for Solar Energy Development in Six Southwestern States (Solar PEIS; BLM and DOE 2012) has been refined based on additional information described below in an expanded hydrogeologic discussion.

  15. Groundwater flow in a coastal peatland and its influence on submarine groundwater discharge

    Science.gov (United States)

    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.

  16. 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

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

    International Nuclear Information System (INIS)

    Orr, B. R.

    1999-01-01

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

  18. Groundwater flow systems in the great Aletsch glacier region (Valais, Switzerland)

    Science.gov (United States)

    Alpiger, Andrea; Loew, Simon

    2014-05-01

    above the terraces of Riederalp and Bettmeralp in or near steeply dipping fault zones striking parallel to the ridge, suggesting locally a near-surface groundwater table. Drying up of several of these springs (at lateral distances up to 4 km) after construction of the Riederhornstollen, as well as associated large tunnel water inflows, demonstrates large scale hydraulic connections along strike of these fault zones. The catchment areas of these springs have to be located close to the ridge crest, above the terraces of Riederalp and Bettmeralp, and extend over many kilometers. This fault system thus drains significant portions of the high-altitude recharge and induces a complex 3D groundwater flow field of the Aletsch area. Variations in glacial ice extent due to different climatic conditions during the Lateglacial and Holocene periods were studied by varying the boundary condition of the great Aletsch glacier. Results have to be interpreted with care, as the glacier pressure boundary conditions were modelled like a lake. Detailed investigations of these boundary conditions have been initialized by glacier drillings equipped with melt water pressure sensors. With the simplified boundary conditions applied to the glacier bed, elevated ice surfaces during the Little Ice Age stage only slightly influence the flow field and total hydraulic head conditions on the NW side of the ridge. On the other hand, the Egesen stadial causes a fundamental change of the groundwater devide with all flow lines, even from below the Aletsch glacier, oriented towards the Rhone valley.

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

    Science.gov (United States)

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

    2017-10-31

    -level decline of 164 feet between 2015 and 2050.Scenario 5 is a modification of Scenario 4 with the addition of two new MPW production wells. For this scenario, the MPW network of production wells were simulated the same as in Scenario 4, but withdrawals from the two new production wells were added in 2020. Simulated 2050 groundwater altitudes for this simulation declined to – 405 feet. Simulated hydrographs for two observation wells show groundwater-level declines of 143 and 51 feet, respectively. Simulated groundwater altitudes at a hypothetical observation well located in the MPW well field declined 199 feet between 2015 and 2050.Scenario 6 is a modification of Scenario 1, in which 140 additional quarterly stress periods were added to simulate MPW seasonal demands. Simulated groundwater altitudes for Scenario 6 declined to –353 feet during 2050. For Scenario 6, simulated hydrographs for two observation wells and the hypothetical observation well show similar groundwater-level declines as seen in Scenario 1, but with seasonal fluctuations of as much as 56 feet in the hypothetical observation well.Water budgets for the model area immediately surrounding Mount Pleasant, South Carolina, were calculated for 2015 and for 2050. The water budget for 2015 is equal for all of the scenarios because it represents the year prior to the hypothetical pumping beginning in 2016. The largest flow component in the 2015 water budget for the Mount Pleasant area is discharge to wells at a rate of 4.17 Mgal/d. Additionally, 0.23 Mgal/d flows laterally out of the Middendorf aquifer in this area of the model due to the regional horizontal hydraulic gradient. Flow into this zone consists predominantly of lateral flow within the Middendorf aquifer at 4.08 Mgal/d. Additionally, 0.02 Mgal/d is released into this zone from aquifer storage. Vertically, 0.06 Mgal/d flows down from the Middendorf confining unit located above the Middendorf aquifer, and 0.25 Mgal/d flows up from the Cape Fear confining

  20. 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.

  1. A Method to Evaluate Groundwater flow system under the Seabed

    Science.gov (United States)

    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.

  2. Structural Control and Groundwater Flow in the Nubian Aquifer

    Science.gov (United States)

    Fathy, K.; Sultan, M.; Ahmed, M.; Save, H.; Emil, M. K.; Elkaliouby, B.

    2017-12-01

    throughout the length (hundreds of kilometers) of the identified shear systems but are dissimilar from those extracted in areas proximal to, but outside of, the shear zones; and (5) basement uplifts impede or redirect the groundwater flow.

  3. Modelling of seasonal dynamics of Wetland-Groundwater flow interaction in the Canadian Prairies

    Science.gov (United States)

    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.

  4. 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

  5. Metamodeling and mapping of nitrate flux in the unsaturated zone and groundwater, Wisconsin, USA

    Science.gov (United States)

    Nolan, Bernard T.; Green, Christopher T.; Juckem, Paul F.; Liao, Lixia; Reddy, James E.

    2018-01-01

    Nitrate contamination of groundwater in agricultural areas poses a major challenge to the sustainability of water resources. Aquifer vulnerability models are useful tools that can help resource managers identify areas of concern, but quantifying nitrogen (N) inputs in such models is challenging, especially at large spatial scales. We sought to improve regional nitrate (NO3−) input functions by characterizing unsaturated zone NO3− transport to groundwater through use of surrogate, machine-learning metamodels of a process-based N flux model. The metamodels used boosted regression trees (BRTs) to relate mappable landscape variables to parameters and outputs of a previous “vertical flux method” (VFM) applied at sampled wells in the Fox, Wolf, and Peshtigo (FWP) river basins in northeastern Wisconsin. In this context, the metamodels upscaled the VFM results throughout the region, and the VFM parameters and outputs are the metamodel response variables. The study area encompassed the domain of a detailed numerical model that provided additional predictor variables, including groundwater recharge, to the metamodels. We used a statistical learning framework to test a range of model complexities to identify suitable hyperparameters of the six BRT metamodels corresponding to each response variable of interest: NO3− source concentration factor (which determines the local NO3− input concentration); unsaturated zone travel time; NO3− concentration at the water table in 1980, 2000, and 2020 (three separate metamodels); and NO3− “extinction depth”, the eventual steady state depth of the NO3−front. The final metamodels were trained to 129 wells within the active numerical flow model area, and considered 58 mappable predictor variables compiled in a geographic information system (GIS). These metamodels had training and cross-validation testing R2 values of 0.52 – 0.86 and 0.22 – 0.38, respectively, and predictions were compiled as maps of the above

  6. Metamodeling and mapping of nitrate flux in the unsaturated zone and groundwater, Wisconsin, USA

    Science.gov (United States)

    Nolan, Bernard T.; Green, Christopher T.; Juckem, Paul F.; Liao, Lixia; Reddy, James E.

    2018-04-01

    Nitrate contamination of groundwater in agricultural areas poses a major challenge to the sustainability of water resources. Aquifer vulnerability models are useful tools that can help resource managers identify areas of concern, but quantifying nitrogen (N) inputs in such models is challenging, especially at large spatial scales. We sought to improve regional nitrate (NO3-) input functions by characterizing unsaturated zone NO3- transport to groundwater through use of surrogate, machine-learning metamodels of a process-based N flux model. The metamodels used boosted regression trees (BRTs) to relate mappable landscape variables to parameters and outputs of a previous "vertical flux method" (VFM) applied at sampled wells in the Fox, Wolf, and Peshtigo (FWP) river basins in northeastern Wisconsin. In this context, the metamodels upscaled the VFM results throughout the region, and the VFM parameters and outputs are the metamodel response variables. The study area encompassed the domain of a detailed numerical model that provided additional predictor variables, including groundwater recharge, to the metamodels. We used a statistical learning framework to test a range of model complexities to identify suitable hyperparameters of the six BRT metamodels corresponding to each response variable of interest: NO3- source concentration factor (which determines the local NO3- input concentration); unsaturated zone travel time; NO3- concentration at the water table in 1980, 2000, and 2020 (three separate metamodels); and NO3- "extinction depth", the eventual steady state depth of the NO3- front. The final metamodels were trained to 129 wells within the active numerical flow model area, and considered 58 mappable predictor variables compiled in a geographic information system (GIS). These metamodels had training and cross-validation testing R2 values of 0.52 - 0.86 and 0.22 - 0.38, respectively, and predictions were compiled as maps of the above response variables. Testing

  7. Application of a hybrid multiscale approach to simulate hydrologic and biogeochemical processes in the river-groundwater interaction zone.

    Energy Technology Data Exchange (ETDEWEB)

    Hammond, Glenn Edward; Yang, Xiaofan; Song, Xuehang; Song, Hyun-Seob; Hou, Zhangshuan; Chen, Xingyuan; Liu, Yuanyuan; Scheibe, Tim

    2017-03-01

    The groundwater-surface water interaction zone (GSIZ) plays an important role in riverine and watershed ecosystems as the exchange of waters of variable composition and temperature (hydrologic exchange flows) stimulate microbial activity and associated biogeochemical reactions. Variable temporal and spatial scales of hydrologic exchange flows, heterogeneity of the subsurface environment, and complexity of biogeochemical reaction networks in the GSIZ present challenges to incorporation of fundamental process representations and model parameterization across a range of spatial scales (e.g. from pore-scale to field scale). This paper presents a novel hybrid multiscale simulation approach that couples hydrologic-biogeochemical (HBGC) processes between two distinct length scales of interest.

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

    Science.gov (United States)

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

    2018-04-01

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

  9. Artificial groundwater recharge zones mapping using remote sensing and GIS: a case study in Indian Punjab.

    Science.gov (United States)

    Singh, Amanpreet; Panda, S N; Kumar, K S; Sharma, Chandra Shekhar

    2013-07-01

    Artificial groundwater recharge plays a vital role in sustainable management of groundwater resources. The present study was carried out to identify the artificial groundwater recharge zones in Bist Doab basin of Indian Punjab using remote sensing and geographical information system (GIS) for augmenting groundwater resources. The study area has been facing severe water scarcity due to intensive agriculture for the past few years. The thematic layers considered in the present study are: geomorphology (2004), geology (2004), land use/land cover (2008), drainage density, slope, soil texture (2000), aquifer transmissivity, and specific yield. Different themes and related features were assigned proper weights based on their relative contribution to groundwater recharge. Normalized weights were computed using the Saaty's analytic hierarchy process. Thematic layers were integrated in ArcGIS for delineation of artificial groundwater recharge zones. The recharge map thus obtained was divided into four zones (poor, moderate, good, and very good) based on their influence to groundwater recharge. Results indicate that 15, 18, 37, and 30 % of the study area falls under "poor," "moderate," "good," and "very good" groundwater recharge zones, respectively. The highest recharge potential area is located towards western and parts of middle region because of high infiltration rates caused due to the distribution of flood plains, alluvial plain, and agricultural land. The least effective recharge potential is in the eastern and middle parts of the study area due to low infiltration rate. The results of the study can be used to formulate an efficient groundwater management plan for sustainable utilization of limited groundwater resources.

  10. 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

  11. 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

  12. Water and rock geochemistry, geologic cross sections, geochemical modeling, and groundwater flow modeling for identifying the source of groundwater to Montezuma Well, a natural spring in central Arizona

    Science.gov (United States)

    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.

  13. 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

  14. 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

  15. 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

  16. 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

  17. 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 ...

  18. 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.

  19. Delineation of groundwater potential zone: An AHP/ANP approach

    Indian Academy of Sciences (India)

    Groundwater; multi-criteria decision making; analytical network process. J. Earth Syst. ... than AHP for decision making. ... the themes and provide utility weights for the alter- natives ... theory that has been applied to classifying ETM+ image.

  20. Groundwater-flow modeling in the Yucatan karstic aquifer, Mexico

    Science.gov (United States)

    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

  1. Ambient groundwater flow diminishes nitrogen cycling in streams

    Science.gov (United States)

    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.

  2. Fluid flow in crystalline rocks: Relationships between groundwater spring alignments and other surface lineations at Altnabreac, United Kingdom

    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

  3. Traffic flow characteristic and capacity in intelligent work zones.

    Science.gov (United States)

    2009-10-15

    Intellgent transportation system (ITS) technologies are utilized to manage traffic flow and safety in : highway work zones. Traffic management plans for work zones require queuing analyses to determine : the anticipated traffic backups, but the predi...

  4. Mechanism and rate of denitrification in an agricultural watershed: Electron and mass balance along groundwater flow paths

    Science.gov (United States)

    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.

  5. Groundwater flow analysis on local scale. Setting boundary conditions for groundwater flow analysis on site scale model in step 1

    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)

  6. 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)

  7. 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...

  8. 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

  9. Groundwater availability as constrained by hydrogeology and environmental flows.

    Science.gov (United States)

    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.

  10. Conceptual Models for Migration of Key Groundwater Contaminants Through the Vadose Zone and Into the Upper Unconfined Aquifer Below the B-Complex

    Energy Technology Data Exchange (ETDEWEB)

    Serne, R. Jeffrey; Bjornstad, Bruce N.; Keller, Jason M.; Thorne, Paul D.; Lanigan, David C.; Christensen, J. N.; Thomas, Gregory S.

    2010-07-01

    The B-Complex contains 3 major crib and trench disposal sites and 3 SST farms that have released nearly 346 mega-liters of waste liquids containing the following high groundwater risk drivers: ~14,000 kg of CN, 29,000 kg of Cr, 12,000 kg of U and 145 Ci of Tc-99. After a thorough review of available vadose zone sediment and pore water, groundwater plume, field gamma logging, field electrical resistivity studies, we developed conceptual models for which facilities have been the significant sources of the contaminants in the groundwater and estimated the masses of these contaminants remaining in the vadose zone and currently present in the groundwater in comparison to the totals released. This allowed us to make mass balance calculations on how consistent our knowledge is on the current deep vadose zone and groundwater distribution of contaminants. Strengths and weaknesses of the conceptual models are discussed as well as implications on future groundwater and deep vadose zone remediation alternatives. Our hypothesized conceptual models attribute the source of all of the cyanide and most of the Tc-99 currently in the groundwater to the BY cribs. The source of the uranium is the BX-102 tank overfill event and the source of most of the chromium is the B-7-A&B and B-8 cribs. Our mass balance estimates suggest that there are much larger masses of U, CN, and Tc remaining in the deep vadose zone within ~20 ft of the water table than is currently in the groundwater plumes below the B-Complex. This hypothesis needs to be carefully considered before future remediation efforts are chosen. The masses of these groundwater risk drivers in the the groundwater plumes have been increasing over the last decade and the groundwater plumes are migrating to the northwest towards the Gable Gap. The groundwater flow rate appears to flucuate in response to seasonal changes in hydraulic gradient. The flux of contaminants out of the deep vadose zone from the three proposed sources also

  11. 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

  12. 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

  13. Microbes Characteristics in Groundwater Flow System in Mountainous Area

    Science.gov (United States)

    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.

  14. Incorporating groundwater flow into the WEPP model

    Science.gov (United States)

    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...

  15. Understanding heat and groundwater flow through continental flood basalt provinces: insights gained from alternative models of permeability/depth relationships for the Columbia Plateau, USA

    Science.gov (United States)

    Burns, Erick R.; Williams, Colin F.; Ingebritsen, Steven E.; Voss, Clifford I.; Spane, Frank A.; DeAngelo, Jacob

    2015-01-01

    Heat-flow mapping of the western USA has identified an apparent low-heat-flow anomaly coincident with the Columbia Plateau Regional Aquifer System, a thick sequence of basalt aquifers within the Columbia River Basalt Group (CRBG). A heat and mass transport model (SUTRA) was used to evaluate the potential impact of groundwater flow on heat flow along two different regional groundwater flow paths. Limited in situ permeability (k) data from the CRBG are compatible with a steep permeability decrease (approximately 3.5 orders of magnitude) at 600–900 m depth and approximately 40°C. Numerical simulations incorporating this permeability decrease demonstrate that regional groundwater flow can explain lower-than-expected heat flow in these highly anisotropic (kx/kz ~ 104) continental flood basalts. Simulation results indicate that the abrupt reduction in permeability at approximately 600 m depth results in an equivalently abrupt transition from a shallow region where heat flow is affected by groundwater flow to a deeper region of conduction-dominated heat flow. Most existing heat-flow measurements within the CRBG are from shallower than 600 m depth or near regional groundwater discharge zones, so that heat-flow maps generated using these data are likely influenced by groundwater flow. Substantial k decreases at similar temperatures have also been observed in the volcanic rocks of the adjacent Cascade Range volcanic arc and at Kilauea Volcano, Hawaii, where they result from low-temperature hydrothermal alteration.

  16. 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

  17. 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

  18. Unsaturated Zone Flow Patterns and Analysis

    Energy Technology Data Exchange (ETDEWEB)

    C. Ahlers

    2001-10-17

    This Analysis/Model Report (AMR) documents the development of an expected-case model for unsaturated zone (UZ) flow and transport that will be described in terms of the representativeness of models of the natural system. The expected-case model will provide an evaluation of the effectiveness of the natural barriers, assess the impact of conservatism in the Total System Performance Assessment (TSPA), and support the development of further models and analyses for public confidence building. The present models used in ''Total System Performance Assessment for the Site Recommendation'' (Civilian Radioactive Waste Management System Management and Operating Contractor (CRWMS M&O) 2000 [1532461]) underestimate the natural-barrier performance because of conservative assumptions and parameters and do not adequately address uncertainty and alternative models. The development of an expected case model for the UZ natural barrier addresses issues regarding flow-pattern analysis and modeling that had previously been treated conservatively. This is in line with the Repository Safety Strategy (RSS) philosophy of treating conservatively those aspects of the UZ flow and transport system that are not important for achieving regulatory dose (CRWMS M&O 2000 [153246], Section 1.1.1). The development of an expected case model for the UZ also provides defense-in-depth in areas requiring further analysis of uncertainty and alternative models. In general, the value of the conservative case is to provide a more easily defensible TSPA for behavior of UZ flow and transport processes at Yucca Mountain. This AMR has been prepared in accordance with the ''Technical Work Plan for Unsaturated Zone (UZ) Flow and Transport Process Model Report'' (Bechtel SAIC Company (BSC) 2001 [155051], Section 1.3 - Work Package 4301213UMG). The work scope is to examine the data and current models of flow and transport in the Yucca Mountain UZ to identify models and analyses

  19. Unsaturated Zone Flow Patterns and Analysis

    International Nuclear Information System (INIS)

    Ahlers, C.

    2001-01-01

    This Analysis/Model Report (AMR) documents the development of an expected-case model for unsaturated zone (UZ) flow and transport that will be described in terms of the representativeness of models of the natural system. The expected-case model will provide an evaluation of the effectiveness of the natural barriers, assess the impact of conservatism in the Total System Performance Assessment (TSPA), and support the development of further models and analyses for public confidence building. The present models used in ''Total System Performance Assessment for the Site Recommendation'' (Civilian Radioactive Waste Management System Management and Operating Contractor (CRWMS M and O) 2000 [1532461]) underestimate the natural-barrier performance because of conservative assumptions and parameters and do not adequately address uncertainty and alternative models. The development of an expected case model for the UZ natural barrier addresses issues regarding flow-pattern analysis and modeling that had previously been treated conservatively. This is in line with the Repository Safety Strategy (RSS) philosophy of treating conservatively those aspects of the UZ flow and transport system that are not important for achieving regulatory dose (CRWMS M and O 2000 [153246], Section 1.1.1). The development of an expected case model for the UZ also provides defense-in-depth in areas requiring further analysis of uncertainty and alternative models. In general, the value of the conservative case is to provide a more easily defensible TSPA for behavior of UZ flow and transport processes at Yucca Mountain. This AMR has been prepared in accordance with the ''Technical Work Plan for Unsaturated Zone (UZ) Flow and Transport Process Model Report'' (Bechtel SAIC Company (BSC) 2001 [155051], Section 1.3 - Work Package 4301213UMG). The work scope is to examine the data and current models of flow and transport in the Yucca Mountain UZ to identify models and analyses where conservatism may be

  20. Surface and subsurface continuous gravimetric monitoring of groundwater recharge processes through the karst vadose zone at Rochefort Cave (Belgium)

    Science.gov (United States)

    Watlet, A.; Van Camp, M. J.; Francis, O.; Poulain, A.; Hallet, V.; Triantafyllou, A.; Delforge, D.; Quinif, Y.; Van Ruymbeke, M.; Kaufmann, O.

    2017-12-01

    Ground-based gravimetry is a non-invasive and integrated tool to characterize hydrological processes in complex environments such as karsts or volcanoes. A problem in ground-based gravity measurements however concerns the lack of sensitivity in the first meters below the topographical surface, added to limited infiltration below the gravimeter building (umbrella effect). Such limitations disappear when measuring underground. Coupling surface and subsurface gravity measurements therefore allow isolating hydrological signals occurring in the zone between the two gravimeters. We present a coupled surface/subsurface continuous gravimetric monitoring of 2 years at the Rochefort Cave Laboratory (Belgium). The gravity record includes surface measurements of a GWR superconducting gravimeter and subsurface measurements of a Micro-g LaCoste gPhone gravimeter, installed in a cave 35 m below the surface station. The recharge of karstic aquifers is extremely complex to model, mostly because karst hydrological systems are composed of strongly heterogeneous flows. Most of the problem comes from the inadequacy of conventional measuring tools to correctly sample such heterogeneous media, and particularly the existence of a duality of flow types infiltrating the vadose zone: from rapid flows via open conduits to slow seepage through porous matrix. Using the surface/subsurface gravity difference, we were able to identify a significant seasonal groundwater recharge within the karst vadose zone. Seasonal or perennial perched reservoirs have already been proven to exist in several karst areas due to the heterogeneity of the porosity and permeability gradient in karstified carbonated rocks. Our gravimetric experiment allows assessing more precisely the recharge processes of such reservoirs. The gravity variations were also compared with surface and in-cave hydrogeological monitoring (i.e. soil moisture, in-cave percolating water discharges, water levels of the saturated zone). Combined

  1. Flow and discharge of groundwater from a snowmelt-affected sandy beach

    Science.gov (United States)

    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.

  2. 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)

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

    Science.gov (United States)

    Senior, Lisa A.; Goode, Daniel J.

    2013-01-01

    by USGS at the site and results from other studies support, and are consistent with, a conceptual model of a layered leaky aquifer where the dip of the beds has a strong control on hydraulic connections in the groundwater system. Connections within and (or) parallel to bedding tend to be greater than across bedding. Transmissivities of aquifer intervals isolated by packers ranged over three orders of magnitude [from about 2.8 to 2,290 square feet per day (ft2/d) or 0.26 to 213 square meters per day (m2/d)], did not appear to differ much by mapped geologic unit, but showed some relation to depth being relatively smaller in the shallowest and deepest intervals (0 to 50 ft and more than 250 ft below land surface, respectively) compared to the intermediate depth intervals (50 to 250 ft below land surface) tested. Transmissivities estimated from multiple-observation well aquifer tests ranged from about 700 to 2,300 ft2/d (65 to 214 m2/d). Results of chemical analyses of water from isolated intervals or monitoring wells open to short sections of the aquifer show vertical differences in concentrations; chloride and silica concentrations generally were greater in shallow intervals than in deeper intervals. Chloride concentrations greater than 100 milligrams per liter (mg/L), combined with distinctive chloride/bromide ratios, indicate a different source of chloride in the western part of North Penn Area 7 than elsewhere in the site. Groundwater flow at a regional scale under steady-state conditions was simulated by use of a numerical model (MODFLOW-2000) for North Penn Area 7 with different layers representing saprolite/highly weathered rock near the surface and unweathered competent bedrock. The sedimentary formations that underlie the study area were modeled using dipping model layers for intermediate and deep zones of unweathered, fractured rock. Horizontal cell model size was 100 meters (m) by 100 meters (328 ft by 328 ft), and model layer thickness ranged from 6 m (19

  4. Groundwater chemistry of shallow aquifers in the coastal zones of Cochin, India

    Digital Repository Service at National Institute of Oceanography (India)

    Laluraj, C.M.; Gopinath, G.; DineshKumar, P.K.

    Laluraj et al.: Groundwater chemistry of shallow aquifers - 133 - APPLIED ECOLOGY AND ENVIRONMENTAL RESEARCH 3(1): 133-139. http://www.ecology.kee.hu ● ISSN 1589 1623  2005, Penkala Bt., Budapest, Hungary GROUNDWATER CHEMISTRY OF SHALLOW AQUIFERS... post monsoon (November 2003) in the coastal zones of Cochin. Laluraj et al.: Groundwater chemistry of shallow aquifers - 134 - APPLIED ECOLOGY AND ENVIRONMENTAL RESEARCH 3(1): 133-139. http://www.ecology.kee.hu ● ISSN 1589 1623  2005, Penkala...

  5. Groundwater composition fluctuation within technogenic zones (case study: flooded coal mines in Primorsky Krai, Russia)

    Science.gov (United States)

    Tarasenko, I. A.; Zinkov, A. V.; Vakh, E. A.; Vetoshkina, A. V.; Strelnikova, A. B.

    2016-03-01

    The paper considers groundwater composition fluctuation within technogenic zones based on evidence from the flooded coal mines of Primorye. The authors have determined the regularities of hydrogeochemical processes, specified the groundwater composition fluctuation within the technogenic complexes located in the liquidated mine areas, and identified the equilibrium phases between the studied waters and specific secondary minerals. It has been proved that water within natural-technogenic complexes in the liquidated mine areas are saturated with silicates, carbonates, sulfates, oxides, and hydroxides, which should be taken into account when designing technologies for groundwater treatment.

  6. Radon concentration distributions in shallow and deep groundwater around the Tachikawa fault zone.

    Science.gov (United States)

    Tsunomori, Fumiaki; Shimodate, Tomoya; Ide, Tomoki; Tanaka, Hidemi

    2017-06-01

    Groundwater radon concentrations around the Tachikawa fault zone were surveyed. The radon concentrations in shallow groundwater samples around the Tachikawa fault segment are comparable to previous studies. The characteristics of the radon concentrations on both sides of the segment are considered to have changed in response to the decrease in groundwater recharge caused by urbanization on the eastern side of the segment. The radon concentrations in deep groundwater samples collected around the Naguri and the Tachikawa fault segments are the same as those of shallow groundwater samples. However, the radon concentrations in deep groundwater samples collected from the bedrock beside the Naguri and Tachikawa fault segments are markedly higher than the radon concentrations expected from the geology on the Kanto plane. This disparity can be explained by the development of fracture zones spreading on both sides of the two segments. The radon concentration distribution for deep groundwater samples from the Naguri and the Tachikawa fault segments suggests that a fault exists even at the southern part of the Tachikawa fault line. Copyright © 2017 Elsevier Ltd. All rights reserved.

  7. 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

  8. Identification of groundwater prospective zones by using remote ...

    Indian Academy of Sciences (India)

    remote sensing and geoelectrical methods in Jharia and. Raniganj coalfields, Dhanbad district, Jharkhand state. Basudeo Rai. 1,∗ ... are most promising for groundwater exploration and dug wells may be dug up to depths of. 30 ± 5 m. 1. ..... Gupta A 1980 Correlation of Landsat and airborne magnetic anomaly data of a part ...

  9. Integrated approach for identification of potential groundwater zones ...

    Indian Academy of Sciences (India)

    The population density of the area is 370 person per sq. km. .... The depth of bore wells on average ranges from 40 to 80m with a ..... draw down pumping test which showed optimum yield of ... izontally stratified earth; Geophysical Prospecting 19. 769–775. ... groundwater potential of India – an estimate based on injected ...

  10. simulation of vertical water flow through vadose zone

    African Journals Online (AJOL)

    HOD

    Simulation of vertical water flow representing the release of water from the vadose zone to the aquifer of surroundings ... ground water pollution from agricultural, industrial and municipal .... Peak Flow Characteristics of Wyoming. Streams: US ...

  11. The influence of heterogeneity on coastal groundwater flow - physical and numerical modeling of fringing reefs, dykes and structured conductivity fields

    Science.gov (United States)

    Houben, Georg J.; Stoeckl, Leonard; Mariner, Katrina E.; Choudhury, Anis S.

    2018-03-01

    Geological heterogeneity of the subsurface, caused by both discrete features and spatially distributed hydraulic conductivity fields, affects the flow of coastal groundwater. It influences the shape and the position of the interface between saltwater and freshwater, as well as the location and flux rate of freshwater discharge to the ocean. Fringing reefs lead to a bimodal regime of freshwater discharge, with discharge at the beach face and through deeper, submarine springs. Impermeable vertical flow barriers (dykes) lead to an impoundment of fresh groundwater and a compartmentalization of the aquifer but also to a delayed expulsion of saline water. Spatially distributed conductivity fields affect the shape of the interface and the geometry of the saltwater wedge. Higher effective conductivities lead to a further landward intrusion of the wedge toe. These flow characteristics can be important for groundwater extraction, the delineation of protection zones and the assessment of contaminant transport to coastal ecosystems.

  12. Climate proxy data as groundwater tracers in regional flow systems

    Science.gov (United States)

    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.

  13. 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

  14. Dead zone area at the downstream flow of barrages

    Directory of Open Access Journals (Sweden)

    Mohamed F. Sauida

    2016-12-01

    Full Text Available Flow separation is a natural phenomenon encountered at some cases downstream of barrages. The main flow is divided into current and dead zone flows. The percentage area of dead zone flow must be taken into consideration downstream of barrages, due to its negative effect on flow characteristics. Experimental studies were conducted in the Hydraulic Research Institute (HRI, on a physical regulator model with five vents. Theoretically the separation zone is described as a part of an ellipse which is practically verified by plotting velocity vectors. The results show that the percentage area of dead zone to the area through length of separation depends mainly on the expansion ratio [channel width to width of opened vents], with maximum value of 81% for operated side gates. A statistical analysis was derived, to predict the percentage area of dead zone flow to the area through length of separation.

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

    Science.gov (United States)

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

    2017-05-04

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

  16. Groundwater flow model for the Little Plover River basin in Wisconsin’s Central Sands

    Science.gov (United States)

    Ken Bradbury,; Fienen, Michael N.; Kniffin, Maribeth; Jacob Krause,; Westenbroek, Stephen M.; Leaf, Andrew T.; Barlow, Paul M.

    2017-01-01

    explicitly includes all high-capacity wells in the model domain and simulates seasonal variations in recharge and well pumping. The model represents the Little Plover River, and other significant streams and drainage ditches in the model domain, as fully connected to the groundwater system, computes stream base flow resulting from groundwater discharge, and routes the flow along the stream channel. A separate soil-water-balance (SWB) model was used to develop groundwater recharge arrays as input for the groundwater flow model. The SWB model uses topography, soils, land use, and climatic data to estimate recharge as deep drainage from the soil zone. The SWB model explicitly includes recharge originating as irrigation water, and computes irrigation using techniques similar to those used by local irrigation operators. The groundwater flow model uses the U.S. Geological Survey’s MODFLOW modeling code which is freely available, widely accepted, and commonly used by the groundwater community. The groundwater flow model and the SWB model use identical high-resolution numerical grids having model cells 100 feet on a side, with physical properties assigned to each grid cell. This grid allows accurate geographic placement of wells, streams, and other model features. The 3-dimensional grid has three layers; layers 1 and 2 represent the sand and gravel aquifer and layer 3 represents the underlying sandstone. The distribution of material properties in the model (hydraulic conductivity, aquifer thickness, etc.) comes from previous published geologic studies of the region, updated by calibration to recent streamflow and groundwater level data. The SWB model operates on a daily time step. The groundwater flow model was calibrated to monthly stress periods with time steps ranging from 1 to 16 days. More detailed time discretization is possible. The groundwater model was calibrated to water-level and streamflow data collected during 2013 and 2014 by adjusting model parameters (primarily

  17. Groundwater monitoring and modelling of the “Vector” site for near-surface radioactive waste disposal in the Chornobyl exclusion zone

    Directory of Open Access Journals (Sweden)

    D. Bugai

    2017-12-01

    Full Text Available Results of purposeful groundwater monitoring and modelling studies are presented, which were carried out in order to better understand groundwater flow patterns from the “Vector” site for near-surface radioactive waste disposal and storage in the Chornobyl exclusion zone towards river network. Both data of observations at local-scale monitoring well network at “Vector” site carried out in 2015 - 2016 and modelling analyses using the regional groundwater flow model of Chornobyl exclusion zone suggest that the groundwater discharge contour for water originating from “Vector” site is Sakhan River, which is the tributary to Pripyat River. The respective groundwater travel time is estimated at 210 - 340 years. The travel times in subsurface for 90Sr, 137Cs, and transuranium radionuclides (Pu isotopes, 241Am are estimated respectively at thousands, tenths of thousands, hundreds of thousands – million of years. These results, as well as presented data of analyses of lithological properties of the geological deposits of the unsaturated zone at “Vector” site, provide evidence for good protection of surface water resources from radioactivity sources (e.g., radioactive wastes to be disposed in the near-sursface facilities at “Vector” site.

  18. 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)

  19. Coupled hydromechanical paleoclimate analyses of density-dependant groundwater flow in discretely fractured crystalline rock settings

    Science.gov (United States)

    Normani, S. D.; Sykes, J. F.; Jensen, M. R.

    2009-04-01

    A high resolution sub-regional scale (84 km2) density-dependent, fracture zone network groundwater flow model with hydromechanical coupling and pseudo-permafrost, was developed from a larger 5734 km2 regional scale groundwater flow model of a Canadian Shield setting in fractured crystalline rock. The objective of the work is to illustrate aspects of regional and sub-regional groundwater flow that are relevant to the long-term performance of a hypothetical nuclear fuel repository. The discrete fracture dual continuum numerical model FRAC3DVS-OPG was used for all simulations. A discrete fracture zone network model delineated from surface features was superimposed onto an 789887 element flow domain mesh. Orthogonal fracture faces (between adjacent finite element grid blocks) were used to best represent the irregular discrete fracture zone network. The crystalline rock between these structural discontinuities was assigned properties characteristic of those reported for the Canadian Shield at the Underground Research Laboratory at Pinawa, Manitoba. Interconnectivity of permeable fracture features is an important pathway for the possibly relatively rapid migration of average water particles and subsequent reduction in residence times. The multiple 121000 year North American continental scale paleoclimate simulations are provided by W.R. Peltier using the University of Toronto Glacial Systems Model (UofT GSM). Values of ice sheet normal stress, and proglacial lake depth from the UofT GSM are applied to the sub-regional model as surface boundary conditions, using a freshwater head equivalent to the normal stress imposed by the ice sheet at its base. Permafrost depth is applied as a permeability reduction to both three-dimensional grid blocks and fractures that lie within the time varying permafrost zone. Two different paleoclimate simulations are applied to the sub-regional model to investigate the effect on the depth of glacial meltwater migration into the subsurface. In

  20. Hydrogeology, groundwater flow, and groundwater quality of an abandoned underground coal-mine aquifer, Elkhorn Area, West Virginia

    Science.gov (United States)

    Kozar, Mark D.; McCoy, Kurt J.; Britton, James Q.; Blake, B.M.

    2017-01-01

    abandoned mine workings in the Pocahontas No. 3 coal seam and underlying strata in various structural settings of the Turkey Gap and adjacent down-dip mines. Geophysical logging and aquifer testing were conducted on the boreholes to locate the coal- mine aquifers, characterize fracture geometry, and define permeable zones within strata overlying and underlying the Pocahontas No. 3 coal-mine aquifer. Water levels were measured monthly in the wells and showed a relatively static phreatic zone within subsided strata a few feet above the top of or within the Pocahontas No. 3 coal-mine aquifer (PC3MA). A groundwater-flow model was developed to verify and refine the conceptual understanding of groundwater flow and to develop groundwater budgets for the study area. The model consisted of four layers to represent overburden strata, the Pocahontas No. 3 coal-mine aquifer, underlying fractured rock, and fractured rock below regional drainage. Simulation of flow in the flooded abandoned mine entries using highly conductive layers or zones within the model, was unable to realistically simulate interbasin transfer of water. Therefore it was necessary to represent the coal-mine aquifer as an internal boundary condition rather than a contrast in aquifer properties. By representing the coal-mine aquifer with a series of drain nodes and optimizing input parameters with parameter estimation software, model errors were reduced dramatically and discharges for Elkhorn Creek, Johns Knob Branch, and other tributaries were more accurately simulated. Flow in the Elkhorn Creek and Johns Knob Branch watersheds is dependent on interbasin transfer of water, primarily from up dip areas of abandoned mine workings in the Pocahontas No. 3 coal-mine aquifer within the Bluestone River watershed to the east. For the 38th, 70th, and 87th percentile flow duration of streams in the region, mean measured groundwater discharge was estimated to be 1.30, 0.47, and 0.39 cubic feet per square mile (ft3/s/mi2

  1. Hydrogeologic Framework Model for the Saturated-Zone Site-Scale Flow

    Energy Technology Data Exchange (ETDEWEB)

    Z. Peterman

    2003-03-05

    Yucca Mountain is being evaluated as a potential site for development of a geologic repository for the permanent disposal of spent nuclear fuel and high-level radioactive waste. Ground water is considered to be the principal means for transporting radionuclides that may be released from the potential repository to the accessible environment, thereby possibly affecting public health and safety. The ground-water hydrology of the region is a result of both the arid climatic conditions and the complex geology. Ground-water flow in the Yucca Mountain region generally can be described as consisting of 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, generally deep-lying, Paleozoic carbonate rock sequence. Locally within the potential repository area, the flow is through a vertical sequence of welded and nonwelded tuffs that overlie the carbonate aquifer. Downgradient from the site, these tuffs terminate in basin fill deposits that are dominated by alluvium. Throughout the system, extensive and prevalent faults and fractures may control ground-water flow. The purpose of this Analysis/Modeling Report (AMR) is to document the three-dimensional (3D) hydrogeologic framework model (HFM) that has been constructed specifically to support development of a site-scale ground-water flow and transport model. Because the HFM provides the fundamental geometric framework for constructing the site-scale 3D ground-water flow model that will be used to evaluate potential radionuclide transport through the saturated zone (SZ) from beneath the potential repository to down-gradient compliance points, the HFM is important for assessing potential repository system performance. This AMR documents the progress of the understanding of the site-scale SZ ground-water flow system framework at Yucca Mountain based on data through July 1999. The

  2. Long-term regional and sub-regional scale groundwater flow within an irregularly fractured Canadian shield setting

    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

  3. Modelling of hydro-zones for layout planning and numerical flow model in 2006

    International Nuclear Information System (INIS)

    Ahokas, H.; Vaittinen, T.; Tammisto, E.; Nummela, J.

    2007-11-01

    As part of the programme for the final disposal of spent nuclear fuel, a model was compiled of hydrogeologically significant zones on the Olkiluoto site. These deterministic zones dominate the groundwater flow especially deep in the bedrock, and because of their nature intersections by disposal tunnels will be avoided, if possible. For layout planning purposes, a brief description was made of the deformation zones of the geological model that intersect the planned repository area and are of hydraulic significance from the point of view of long-term safety. In addition, the hydraulic properties of the zones and the bedrock outside the zones needed for the numerical flow simulations were described. Modelling was mainly based on hydrological observations including an extensive number of single-hole hydraulic tests as well as some long-term pumping test results. Some geophysical mise-a-la-masse results were also used in the compilation of the zones. A comparison between the modelled hydrogeological zones and the deformation zones identified in the geological model of the Olkiluoto site is also presented. (orig.)

  4. Geochemical and Isotopic Interpretations of Groundwater Flow in the Oasis Valley Flow System, Southern Nevada

    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

  5. Effects of tunneling on groundwater flow and swelling of clay-sulfate rocks

    Science.gov (United States)

    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.

  6. Separation of base flow from streamflow using groundwater levels - illustrated for the Pang catchment (UK)

    NARCIS (Netherlands)

    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

  7. BUILDING CONCEPTUAL AND MATHEMATICAL MODEL FOR WATER FLOW AND SOLUTE TRANSPORT IN THE UNSATURATED ZONE AT KOSNICA SITE

    Directory of Open Access Journals (Sweden)

    Stanko Ružičić

    2012-12-01

    Full Text Available Conceptual model of flow and solute transport in unsaturated zone at Kosnica site, which is the basis for modeling pollution migration through the unsaturated zone to groundwater, is set up. The main characteristics of the unsaturated zone of the Kosnica site are described. Detailed description of investigated profile of unsaturated zone, with all necessary analytical results performed and used in building of conceptual models, is presented. Experiments that are in progress and processes which are modeled are stated. Monitoring of parameters necessary for calibration of models is presented. The ultimate goal of research is risk assessment of groundwater contamination at Kosnica site that has its source in or on unsaturated zone.

  8. Numerical simulation of groundwater flow, resource optimization, and potential effects of prolonged drought for the Citizen Potawatomi Nation Tribal Jurisdictional Area, central Oklahoma

    Science.gov (United States)

    Ryter, Derek W.; Kunkel, Christopher D.; Peterson, Steven M.; Traylor, Jonathan P.

    2015-08-13

    A hydrogeological study including two numerical groundwater-flow models was completed for the Citizen Potawatomi Nation Tribal Jurisdictional Area of central Oklahoma. One numerical groundwater-flow model, the Citizen Potawatomi Nation model, encompassed the jurisdictional area and was based on the results of a regional-scale hydrogeological study and numerical groundwater flow model of the Central Oklahoma aquifer, which had a geographic extent that included the Citizen Potawatomi Nation Tribal Jurisdictional Area. The Citizen Potawatomi Nation numerical groundwater-flow model included alluvial aquifers not in the original model and improved calibration using automated parameter-estimation techniques. The Citizen Potawatomi Nation numerical groundwater-flow model was used to analyze the groundwater-flow system and the effects of drought on the volume of groundwater in storage and streamflow in the North Canadian River. A more detailed, local-scale inset model was constructed from the Citizen Potawatomi Nation model to estimate available groundwater resources for two Citizen Potawatomi Nation economic development zones near the North Canadian River, the geothermal supply area and the Iron Horse Industrial Park.

  9. 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

  10. Hydraulic effects of unsealed boreholes. Numerical groundwater flow modelling of the Forsmark and Laxemar sites

    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

  11. Hydraulic effects of unsealed boreholes. Numerical groundwater flow modelling of the Forsmark and Laxemar sites

    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

  12. Common problematic aspects of coupling hydrological models with groundwater flow models on the river catchment scale

    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.

  13. Decomposition of groundwater level fluctuations using transfer modelling in an area with shallow to deep unsaturated zones

    Science.gov (United States)

    Gehrels, J. C.; van Geer, F. C.; de Vries, J. J.

    1994-05-01

    Time series analysis of the fluctuations in shallow groundwater levels in the Netherlands lowlands have revealed a large-scale decline in head during recent decades as a result of an increase in land drainage and groundwater withdrawal. The situation is more ambiguous in large groundwater bodies located in the eastern part of the country, where the unsaturated zone increases from near zero along the edges to about 40 m in the centre of the area. As depth of the unsaturated zone increases, groundwater level reacts with an increasing delay to fluctuations in climate and influences of human activities. The aim of the present paper is to model groundwater level fluctuations in these areas using a linear stochastic transfer function model, relating groundwater levels to estimated precipitation excess, and to separate artificial components from the natural groundwater regime. In this way, the impact of groundwater withdrawal and the reclamation of a 1000 km 2 polder area on the groundwater levels in the adjoining higher ground could be assessed. It became evident that the linearity assumption of the transfer functions becomes a serious drawback in areas with the deepest groundwater levels, because of non-linear processes in the deep unsaturated zone and the non-synchronous arrival of recharge in the saturated zone. Comparison of the results from modelling the influence of reclamation with an analytical solution showed that the lowering of groundwater level is partly compensated by reduced discharge and therefore is less than expected.

  14. Vadose zone processes delay groundwater nitrate reduction response to BMP implementation as observed in paired cultivated vs. uncultivated potato rotation fields

    Science.gov (United States)

    Jiang, Y.; Nyiraneza, J.; Murray, B. J.; Chapman, S.; Malenica, A.; Parker, B.

    2017-12-01

    Nitrate leaching from crop production contributes to groundwater contamination and subsequent eutrophication of the receiving surface water. A study was conducted in a 7-ha potato-grain-forages rotation field in Prince Edward Island (PEI), Canada during 2011-2016 to link potato rotation practices and groundwater quality. The field consists of fine sandy loam soil and is underlain by 7-9 m of glacial till, which overlies the regional fractured ;red-bed; sandstone aquifer. The water table is generally located in overburden close to the bedrock interface. Field treatments included one field zone taken out of production in 2011 with the remaining zones kept under a conventional potato rotation. Agronomy data including crop tissue, soil, and tile-drain water quality were collected. Hydrogeology data including multilevel monitoring of groundwater nitrate and hydraulic head and data from rock coring for nitrate distribution in overburden and bedrock matrix were also collected. A significant amount of nitrate leached below the soil profile after potato plant kill (referred to as topkill) in 2011, most of it from fertilizer N. A high level of nitrate was also detected in the till vadose zone through coring in December 2012 and through multilevel groundwater sampling from January to May 2014 in both cultivated and uncultivated field zones. Groundwater nitrate concentrations increased for about 2.5 years after the overlying potato field was removed from production. Pressure-driven uniform flow processes dominate water and nitrate transport in the vadose zone, producing an apparently instant water table response but a delayed groundwater quality response to nitrate leaching events. These data suggest that the uniform flow dominated vadose zone in agricultural landscapes can cause the accumulation of a significant amount of nitrate originated from previous farming activities, and the long travel time of this legacy nitrate in the vadose zone can result in substantially delayed

  15. 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

  16. New approach for simulating groundwater flow in discrete fracture network

    Science.gov (United States)

    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.

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

    Science.gov (United States)

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

    2017-10-20

    representation of subsurface geology and explicitly simulates the effects of hydrologically important fault zones not included in the previous model.The upper Deschutes Basin GSFLOW model was calibrated using an iterative trial and error approach using measured water-level elevations (water levels) from 800 wells, 144 of which have time series of 10 or more measurements. Streamflow was calibrated using data from 21 gage locations. At 14 locations where measured flows are heavily influenced by reservoir operations and irrigation diversions, so called “naturalized” flows, with the effects of reservoirs and diversion removed, developed by the Bureau of Reclamation, were used for calibration. Surface energy and moisture processes such as solar radiation, snow accumulation and melting, and evapotranspiration were calibrated using national datasets as well as data from long-term measurement sites in the basin. The calibrated Deschutes GSFLOW model requires daily precipitation, minimum and maximum air temperature data, and monthly data describing groundwater pumping and artificial recharge from leaking irrigation canals (which are a significant source of groundwater recharge).The calibrated model simulates the geographic distribution of hydraulic head over the 5,000 ft range measured in the basin, with a median absolute residual of about 53 ft. Temporal variations in head resulting from climate cycles, pumping, and canal leakage are well simulated over the model area. Simulated daily streamflow matches gaged flows or calculated naturalized flows for streams including the Crooked and Metolius Rivers, and lower parts of the mainstem Deschutes River. Seasonal patterns of runoff are less well fit in some upper basin streams. Annual water balances of streamflow are good over most of the model domain. Model fit and overall capabilities are appropriate for the objectives of the project.The integrated model results confirm findings from other studies and models indicating that most

  18. Uranium-series constraints on radionuclide transport and groundwater flow at the Nopal I uranium deposit, Sierra Pena Blanca, Mexico

    Energy Technology Data Exchange (ETDEWEB)

    Goldstein, S.J.; Abdel-Fattah, A.I.; Murrell, M.T.; Dobson, P.F.; Norman, D.E.; Amato, R.S.; Nunn, A. J.

    2009-10-01

    Uranium-series data for groundwater samples from the Nopal I uranium ore deposit were obtained to place constraints on radionuclide transport and hydrologic processes for a nuclear waste repository located in fractured, unsaturated volcanic tuff. Decreasing uranium concentrations for wells drilled in 2003 are consistent with a simple physical mixing model that indicates that groundwater velocities are low ({approx}10 m/y). Uranium isotopic constraints, well productivities, and radon systematics also suggest limited groundwater mixing and slow flow in the saturated zone. Uranium isotopic systematics for seepage water collected in the mine adit show a spatial dependence which is consistent with longer water-rock interaction times and higher uranium dissolution inputs at the front adit where the deposit is located. Uranium-series disequilibria measurements for mostly unsaturated zone samples indicate that {sup 230}Th/{sup 238}U activity ratios range from 0.005-0.48 and {sup 226}Ra/{sup 238}U activity ratios range from 0.006-113. {sup 239}Pu/{sup 238}U mass ratios for the saturated zone are <2 x 10{sup -14}, and Pu mobility in the saturated zone is >1000 times lower than the U mobility. Saturated zone mobility decreases in the order {sup 238}U{approx}{sup 226}Ra > {sup 230}Th{approx}{sup 239}Pu. Radium and thorium appear to have higher mobility in the unsaturated zone based on U-series data from fractures and seepage water near the deposit.

  19. Uranium-series constraints on radionuclide transport and groundwater flow at the Nopal I uranium deposit, Sierra Pena Blanca, Mexico

    International Nuclear Information System (INIS)

    Goldstein, S.J.; Abdel-Fattah, A.I.; Murrell, M.T.; Dobson, P.F.; Norman, D.E.; Amato, R.S.; Nunn, A.J.

    2009-01-01

    Uranium-series data for groundwater samples from the Nopal I uranium ore deposit were obtained to place constraints on radionuclide transport and hydrologic processes for a nuclear waste repository located in fractured, unsaturated volcanic tuff. Decreasing uranium concentrations for wells drilled in 2003 are consistent with a simple physical mixing model that indicates that groundwater velocities are low (∼10 m/y). Uranium isotopic constraints, well productivities, and radon systematics also suggest limited groundwater mixing and slow flow in the saturated zone. Uranium isotopic systematics for seepage water collected in the mine adit show a spatial dependence which is consistent with longer water-rock interaction times and higher uranium dissolution inputs at the front adit where the deposit is located. Uranium-series disequilibria measurements for mostly unsaturated zone samples indicate that 230 Th/ 238 U activity ratios range from 0.005-0.48 and 226 Ra/ 238 U activity ratios range from 0.006-113. 239 Pu/ 238 U mass ratios for the saturated zone are -14 , and Pu mobility in the saturated zone is >1000 times lower than the U mobility. Saturated zone mobility decreases in the order 238 U∼ 226 Ra > 230 Th∼ 239 Pu. Radium and thorium appear to have higher mobility in the unsaturated zone based on U-series data from fractures and seepage water near the deposit.

  20. Persistence of uranium groundwater plumes: Contrasting mechanisms at two DOE sites in the groundwater-river interaction zone

    Science.gov (United States)

    Zachara, John M.; Long, Philip E.; Bargar, John; Davis, James A.; Fox, Patricia; Fredrickson, Jim K.; Freshley, Mark D.; Konopka, Allan E.; Liu, Chongxuan; McKinley, James P.; Rockhold, Mark L.; Williams, Kenneth H.; Yabusaki, Steve B.

    2013-04-01

    We examine subsurface uranium (U) plumes at two U.S. Department of Energy sites that are located near large river systems and are influenced by groundwater-river hydrologic interaction. Following surface excavation of contaminated materials, both sites were projected to naturally flush remnant uranium contamination to levels below regulatory limits (e.g., 30 μg/L or 0.126 μmol/L; U.S. EPA drinking water standard), with 10 years projected for the Hanford 300 Area (Columbia River) and 12 years for the Rifle site (Colorado River). The rate of observed uranium decrease was much lower than expected at both sites. While uncertainty remains, a comparison of current understanding suggests that the two sites have common, but also different mechanisms controlling plume persistence. At the Hanford 300 A, the persistent source is adsorbed U(VI) in the vadose zone that is released to the aquifer during spring water table excursions. The release of U(VI) from the vadose zone and its transport within the oxic, coarse-textured aquifer sediments is dominated by kinetically-limited surface complexation. Modeling implies that annual plume discharge volumes to the Columbia River are small (oxidation of naturally reduced, contaminant U(IV) in the saturated zone and a continuous influx of U(VI) from natural, up-gradient sources influence plume persistence. Rate-limited mass transfer and surface complexation also control U(VI) migration velocity in the sub-oxic Rifle groundwater. Flux of U(VI) from the vadose zone at the Rifle site may be locally important, but it is not the dominant process that sustains the plume. A wide range in microbiologic functional diversity exists at both sites. Strains of Geobacter and other metal reducing bacteria are present at low natural abundance that are capable of enzymatic U(VI) reduction in localized zones of accumulated detrital organic carbon or after organic carbon amendment. Major differences between the sites include the geochemical nature of

  1. Persistence of uranium groundwater plumes: contrasting mechanisms at two DOE sites in the groundwater-river interaction zone.

    Science.gov (United States)

    Zachara, John M; Long, Philip E; Bargar, John; Davis, James A; Fox, Patricia; Fredrickson, Jim K; Freshley, Mark D; Konopka, Allan E; Liu, Chongxuan; McKinley, James P; Rockhold, Mark L; Williams, Kenneth H; Yabusaki, Steve B

    2013-04-01

    We examine subsurface uranium (U) plumes at two U.S. Department of Energy sites that are located near large river systems and are influenced by groundwater-river hydrologic interaction. Following surface excavation of contaminated materials, both sites were projected to naturally flush remnant uranium contamination to levels below regulatory limits (e.g., 30 μg/L or 0.126 μmol/L; U.S. EPA drinking water standard), with 10 years projected for the Hanford 300 Area (Columbia River) and 12 years for the Rifle site (Colorado River). The rate of observed uranium decrease was much lower than expected at both sites. While uncertainty remains, a comparison of current understanding suggests that the two sites have common, but also different mechanisms controlling plume persistence. At the Hanford 300 A, the persistent source is adsorbed U(VI) in the vadose zone that is released to the aquifer during spring water table excursions. The release of U(VI) from the vadose zone and its transport within the oxic, coarse-textured aquifer sediments is dominated by kinetically-limited surface complexation. Modeling implies that annual plume discharge volumes to the Columbia River are small (oxidation of naturally reduced, contaminant U(IV) in the saturated zone and a continuous influx of U(VI) from natural, up-gradient sources influence plume persistence. Rate-limited mass transfer and surface complexation also control U(VI) migration velocity in the sub-oxic Rifle groundwater. Flux of U(VI) from the vadose zone at the Rifle site may be locally important, but it is not the dominant process that sustains the plume. A wide range in microbiologic functional diversity exists at both sites. Strains of Geobacter and other metal reducing bacteria are present at low natural abundance that are capable of enzymatic U(VI) reduction in localized zones of accumulated detrital organic carbon or after organic carbon amendment. Major differences between the sites include the geochemical nature of

  2. Documentation for the MODFLOW 6 Groundwater Flow Model

    Science.gov (United States)

    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

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

    Science.gov (United States)

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

    2014-01-01

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

  4. 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.

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

    Science.gov (United States)

    Juckem, Paul F.; Dunning, Charles P.

    2015-01-01

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

  6. Fracture detection and groundwater flow characterization in poorly exposed ground using helium and radon in soil gases

    International Nuclear Information System (INIS)

    Gascoyne, M.; Wuschke, D.M.

    1991-05-01

    Radon and helium in soil gases have been used to identify locations of groundwater discharge and the presence of fractures outcropping beneath overburden in two areas near the Underground Research Laboratory (URL), Lac du Bonnet, Manitoba, Canada. In particular, groundwater discharge from a known, inclined fracture zone at the URL was clearly identified by a helium excess in overlying soil gases. A model was developed to describe gas phase flow in bedrock and overburden at this location, from gas injection in an adjacent borehole. Predictions were made of gas transport pathway and breakthrough time at the surface, in preparation for a gas injection test

  7. From groundwater baselines to numerical groundwater flow modelling for the Milan metropolitan area

    Science.gov (United States)

    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.

  8. 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

  9. Numerical Study of Heat Transfer during Artificial Ground Freezing Combined with Groundwater Flow based on in-situ Measurement

    Science.gov (United States)

    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

  10. A correction on coastal heads for groundwater flow models.

    Science.gov (United States)

    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.

  11. Time Lapse Electrical Resistivity to Connect Evapotranspiration and Groundwater Fluxes in the Critical Zone

    Science.gov (United States)

    Jarvis, S. K.; Harmon, R. E.; Barnard, H. R.; Randall, J.; Singha, K.

    2017-12-01

    The critical zone (CZ)—an open system extending from canopy top to the base of groundwater—is a highly dynamic and heterogeneous environment. In forested terrain, trees make up a large component of the CZ. This work aims to quantify the connection between vegetation and subsurface water storage at a hillslope scale within a forested watershed in the H.J. Andrews Experimental Forest, Oregon. To identify the mechanism(s) controlling the connection at the hillslope scale, we observe patterns in electrical conductivity using 2D-time lapse-DC resistivity. To compare inversions through time a representative error model was determined using L-curve criterion. Inverted data show high spatial variability in ground electrical conductivity and variation at both diel and seasonal timescales. These changes are most pronounced in areas corresponding to dense vegetation. The diel pattern in electrical conductivity is also observed in monitored sap flow sensors, water-level gauges, tensiometers, and sediment thermal probes. To quantify the temporal connection between these data over the course of the growing season a cross correlation analysis was conducted. Preliminary data show that over the course of the growing season transpiration becomes decoupled from both groundwater and soil moisture. Further decomposition of the inverted time lapse data will highlight spatial variability in electrical conductivity providing insight into the where, when, and how(s) of tree-modified subsurface storage.

  12. Delineation of groundwater potential zones in Theni district, Tamil Nadu, using remote sensing, GIS and MIF techniques

    Directory of Open Access Journals (Sweden)

    N.S. Magesh

    2012-03-01

    Full Text Available Integration of remote sensing data and the geographical information system (GIS for the exploration of groundwater resources has become a breakthrough in the field of groundwater research, which assists in assessing, monitoring, and conserving groundwater resources. In the present paper, various groundwater potential zones for the assessment of groundwater availability in Theni district have been delineated using remote sensing and GIS techniques. Survey of India toposheets and IRS-1C satellite imageries are used to prepare various thematic layers viz. lithology, slope, land-use, lineament, drainage, soil, and rainfall were transformed to raster data using feature to raster converter tool in ArcGIS. The raster maps of these factors are allocated a fixed score and weight computed from multi influencing factor (MIF technique. Moreover, each weighted thematic layer is statistically computed to get the groundwater potential zones. The groundwater potential zones thus obtained were divided into four categories, viz., very poor, poor, good, and very good zones. The result depicts the groundwater potential zones in the study area and found to be helpful in better planning and management of groundwater resources.

  13. Radiotracer technique to study pollutant behavior in the vadose zone for groundwater protection

    International Nuclear Information System (INIS)

    Kulkarni, U.P.; Sinha, U.K.; Navada, S.V.; Datta, P.S.; Sud, Y.K.; Kulkarni, K.M.; Aggrawal, P.; )

    2004-01-01

    Pollutants are generated either by industrial or agricultural activity. Pollutants produced due to industrial activities fall into point source category and those generated from agricultural are grouped into extended source category. Under an International Atomic Energy Agency/Coordinated Research Program study, emphasis has been given on transport of pollutants, generated from agricultural activities, in particular, due to the application of fertilizer inputs to a variety of crops. Pollutants take entry through the vadose zone and ultimately join the saturated zone. Once groundwater is polluted it is rather difficult or impossible to take remedial measures for groundwater protection. Groundwater being an important natural resource, it is important to protect it from getting polluted. It is hence essential to have a clear understanding of the complex processes (physical, biological and chemical etc.) undergoing in the unsaturated zone. Radiotracers give good insight about the pollutant behavior in the vadose zone. Tritiated water and 60 Co (a gamma emitting tracer in the cyanide complex form) were used as tracers and were injected at 60 cm depth in the vadose zone of IARI farm for pollutant transport study. Tritium and 60 Co tracer displacements were measured by liquid scintillation and sodium iodide scintillation method respectively. It was found that the tritium tracer moved up to 2.4 meters in six months and part of the tritium tracer was exchanged with immobile water in the soil, as three distinct peaks were observed in tritium profile. 60 Co and tritium tracers were found to move with the same velocity in the vadose zone. These tracer studies indicate that the pollutants may reach the groundwater in about three years. (author)

  14. Hydrogeology, simulated ground-water flow, and ground-water quality, Wright-Patterson Air Force Base, Ohio

    Science.gov (United States)

    Dumouchelle, D.H.; Schalk, C.W.; Rowe, G.L.; De Roche, J.T.

    1993-01-01

    percent of the total ground-water flow in the study area. Ground waters in the vicinity of Wright-Patterson Air Force Base can be classified into two compositional groups on the basis of their chemical composition: calcium magnesium bicarbonate-type and sodium chloride-type waters. Calcium magnesium bicarbonate-type waters are found in the glacial deposits and the Brassfield Limestone, whereas the sodium chloride waters are exclusively associated with the shales. Equilibrium speciation calculations indicate that ground water of the glacial drift aquifer is in equilibrium with calcite, dolomite, and chalcedony, but is undersaturated with respect to gypsum and fluorite. Waters from the shales are slightly supersaturated with respect to calcite, dolomite, and siderite but are undersaturated with respect to chalcedony. Simple-mass balance calculations treating boron as a conservative species indicate that little (origin for all ground water beneath Wright-Patterson Air Force Base, but the data were inconclusive with respect to identification of distinct isotopic differences between water collected from the glacial drift and bedrock aquifers. Tritium concentrations used to distinguish waters having a pre-and post-1953 recharge component indicate that most water entered the glacial drift aquifer after 1953. This finding indicates that recharge from shallow to deep parts (greater than 150 feet) of the aquifer takes place over time intervals of a few years or decades. However, the fact that some deep parts of the glacial aquifer did not contain measurable tritium indicates that ground-water flow from recharge zones to these parts of the aquifer takes decades or longer.

  15. Imbalance in Groundwater-Surface Water Interactions and its Relationship to the Coastal Zone Hazards

    Science.gov (United States)

    Kontar, Y. A.; Ozorovich, Y. R.; Salokhiddinov, A. T.

    2011-12-01

    We report here some efforts and results in studying the imbalance in groundwater-surface water interactions and processes of groundwater-surface water interactions and groundwater flooding creating hazards in the coastal zones. Hazards, hydrological and geophysical risk analysis related to imbalance in groundwater-surface water interactions and groundwater flooding have been to a large extent under-emphasized for coastal zone applications either due to economical limitations or underestimation of significance of imbalance in groundwater-surface water interactions. This is particularly true for tsunamis creating salt water intrusion to coastal aquifers, even though most tsunami hazard assessments have in the past relied on scenario or deterministic type models, and to increasing mineralization of potable water because of intensive water diversions and also the abundance of highly toxic pollutants (mainly pesticides) in water, air and food, which contribute to the deterioration of the coastal population's health. In the wake of pressing environmental and economic issues, it is of prime importance for the scientific community to shed light onto the great efforts by hydrologists and geophysicists to quantify conceptual uncertainties and to provide quality assurances of potential coastal zone hazard evaluation and prediction under conditions of imbalance in groundwater-surface water interactions. This paper proposes consideration of two case studies which are important and significant for future understanding of a concept of imbalance in groundwater-surface water interactions and development and essential for feasibility studies of hazards in the coastal zone. The territory of the Aral Sea Region in Central Asia is known as an ecological disaster coastal zone. It is now obvious that, in order to provide reasonable living conditions to the coastal zone population, it is first of all necessary to drastically improve the quality of the water dedicated to human needs. Due

  16. Deciphering groundwater potential zones in hard rock terrain using geospatial technology.

    Science.gov (United States)

    Dar, Imran A; Sankar, K; Dar, Mithas A

    2011-02-01

    Remote sensing and geographical information system (GIS) has become one of the leading tools in the field of groundwater research, which helps in assessing, monitoring, and conserving groundwater resources. This paper mainly deals with the integrated approach of remote sensing and GIS to delineate groundwater potential zones in hard rock terrain. Digitized vector maps pertaining to chosen parameters, viz. geomorphology, geology, land use/land cover, lineament, relief, and drainage, were converted to raster data using 23 m×23 m grid cell size. Moreover, curvature of the study area was also considered while manipulating the spatial data. The raster maps of these parameters were assigned to their respective theme weight and class weights. The individual theme weight was multiplied by its respective class weight and then all the raster thematic layers were aggregated in a linear combination equation in Arc Map GIS Raster Calculator module. Moreover, the weighted layers were statistically modeled to get the areal extent of groundwater prospects with respect to each thematic layer. The final result depicts the favorable prospective zones in the study area and can be helpful in better planning and management of groundwater resources especially in hard rock terrains.

  17. Groundwater quality for irrigation of deep aquifer in southwestern zone of Bangladesh

    Directory of Open Access Journals (Sweden)

    Mirza A.T.M. Tanvir Rahman

    2012-07-01

    Full Text Available In coastal regions of Bangladesh, sources of irrigation are rain, surface and groundwater. Due to rainfall anomaly andsaline contamination, it is important to identify deep groundwater that is eligible for irrigation. The main goal of the study wasto identify deep groundwater which is suitable for irrigation. Satkhira Sadar Upazila, at the southwestern coastal zone ofBangladesh, was the study area, which was divided into North, Center and South zones. Twenty samples of groundwaterwere analyzed for salinity (0.65-4.79 ppt, sodium absorption ratio (1.14-11.62, soluble sodium percentage (32.95-82.21, electricalconductivity (614-2082.11 μS/cm, magnesium adsorption ratio (21.96-26.97, Kelly’s ratio (0.48-4.62, total hardness(150.76-313.33 mg/l, permeability index (68.02-94.16 and residual sodium bi-carbonate (79.68-230.72 mg/l. Chemical constituentsand values were compared with national and international standards. Northern deep groundwater has the highest salinityand chemical concentrations. Salinity and other chemical concentrations show a decreasing trend towards the south. Lowchemical concentrations in the southern region indicate the best quality groundwater for irrigation.

  18. The Practical Application of Aqueous Geochemistry in Mapping Groundwater Flow Systems in Fractured Rock Masses

    Science.gov (United States)

    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

  19. 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

    groundwater level and the hydraulic heads in the deep drill holes. However, due to a lack of representative salinity samples in the monitoring system and, in particular, a lack of a time series for the observations, it was difficult to judge the validity of the salinity model when tunnels were present. The current study also took the first steps to incorporate more heterogeneity (with respect to the transmissivity of the zones and the conductivity of sparsely fractured rock) in the flow model. In addition, a preliminary analysis was conducted to evaluate uncertainties and sensitivities by means of the Ensemble Kalman filter. (orig.)

  20. Qualitative zoning of groundwater for drinking purposes in Lenjan plain using GQI method through GIS

    Directory of Open Access Journals (Sweden)

    Amin Mohebbi Tafreshi

    2017-09-01

    Full Text Available Background: A new method has been presented specifically for zoning the quality of groundwater for drinking purposes; this method is the groundwater quality index (GQI method. The present research used the GQI method to qualitatively zoning of the Lenjan groundwater for drinking purposes. Methods: Three phases were applied in this research. In the first phase, working on the quality data of 38 wells within the studied plain, the raster map of quality concentration parameters, including pH, TDS, Cl, SO4, Ca, Mg, and Na parameters, was provided by interpolation using the kriging method in the ArcGIS software. In the second phase, the mentioned maps were standardized so that various bits of data can follow a common standard and scale. In the third phase, weight was applied to each standardized map, and ultimately the classification map for each parameter was drawn. The final GQI map was created by combining the mentioned classification maps. Results: The GQI values for Lenjan plain were rated from the minimum (67.48 to the maximum (90.05. The results showed an average to acceptable level of quality for drinking water. Conclusion: According to the final map, the central and southern parts of Lenjan plain, which have acceptable GQI rankings, are the best zones from which to use groundwater for drinking purposes.

  1. Developing a methodology for identifying action zones to protect and manage groundwater well fields

    Science.gov (United States)

    Bellier, Sandra; Viennot, Pascal; Ledoux, Emmanuel; Schott, Celine

    2013-04-01

    Implementation of a long term action plan to manage and protect well fields is a complex and very expensive process. In this context, the relevance and efficiency of such action plans on water quality should be evaluated. The objective of this study is to set up a methodology to identify relevant actions zones in which environmental changes may significantly impact the quantity or quality of pumped water. In the Seine-et-Marne department (France), under French environmental laws three sectors integrating numerous well-field pumping in Champigny's limestone aquifer are considered as priority. This aquifer, located at south-east of Paris, supplies more than one million people with drinking water. Catchments areas of these abstractions are very large (2000 km2) and their intrinsic vulnerability was established by a simple parametric approach that does not permit to consider the complexity of hydrosystem. Consequently, a methodology based on a distributed modeling of the process of the aquifer was developed. The basin is modeled using the hydrogeological model MODCOU, developed in MINES ParisTech since the 1980s. It simulates surface and groundwater flow in aquifer systems and allows to represent the local characteristics of the hydrosystem (aquifers communicating by leakage, rivers infiltration, supply from sinkholes and locally perched or dewatering aquifers). The model was calibrated by matching simulated river discharge hydrographs and piezometric heads with observed ones since the 1970s. Thanks to this modelling tool, a methodology based on the transfer of a theoretical tracer through the hydrosystem from the ground surface to the outlets was implemented to evaluate the spatial distribution of the contribution areas at contrasted, wet or dry recharge periods. The results show that the surface of areas contributing to supply most catchments is lower than 300 km2 and the major contributory zones are located along rivers. This finding illustrates the importance of

  2. Unsaturated Groundwater Flow Beneath Upper Mortandad Canyon, Los Alamos, New Mexico

    Energy Technology Data Exchange (ETDEWEB)

    Dander, David Carl [Univ. of Arizona, Tucson, AZ (United States)

    1998-10-15

    Mortandad Canyon is a discharge site for treated industrial effluents containing radionuclides and other chemicals at Los Alamos National Laboratory, New Mexico. This study was conducted to develop an understanding of the unsaturated hydrologic behavior below the canyon floor. The main goal of this study was to evaluate the hypothetical performance of the vadose zone above the water table. Numerical simulations of unsaturated groundwater flow at the site were conducted using the Finite Element Heat and Mass Transfer (FEHM) code. A two-dimensional cross-section along the canyon's axis was used to model flow between an alluvial groundwater system and the regional aquifer approximately 300 m below. Using recharge estimated from a water budget developed in 1967, the simulations showed waters from the perched water table reaching the regional aquifer in 13.8 years, much faster than previously thought. Additionally, simulations indicate that saturation is occurring in the Guaje pumice bed an d that the Tshirege Unit 1B is near saturation. Lithologic boundaries between the eight materials play an important role in flow and solute transport within the system. Horizontal flow is shown to occur in three thin zones above capillary barriers; however, vertical flow dominates the system. Other simulations were conducted to examine the effects of changing system parameters such as varying recharge inputs, varying the distribution of recharge, and bypassing fast-path fractured basalt of uncertain extent and properties. System sensitivity was also explored by changing model parameters with respect to size and types of grids and domains, and the presence of dipping stratigraphy.

  3. Composite use of numerical groundwater flow modeling and geoinformatics techniques for monitoring Indus Basin aquifer, Pakistan.

    Science.gov (United States)

    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.

  4. The Implication of Agricultural Expansion on the Groundwater Flow Regime of Saq Aquifer in Al Qassim Region, Saudi Arabia

    Science.gov (United States)

    Alharbi, T.; Mansour Helmy, B. M.

    2017-12-01

    Al-Qassim Region in Saudi Arabia is characterized by expanding agricultural activities. Most agricultural fields are irrigated by groundwater, mainly from the Saq aquifer. Excessive water extraction from this aquifer and arid climatic conditions negatively alter the quality and quantity of the groundwater. In this study, detailed hydrological and hydrogeological investigations were carried out to characterize spatially the potential groundwater recharge zones, deal with the estimation of groundwater balance of the Saq aquifer in the study area and to assess the safe yield of the aquifer. Accordingly, the implication of agricultural expansion on groundwater flow regime of Saq aquifer and its relation with safe yield and groundwater recharge was evaluated. The water-budget was calculated and the main water Inputs and outputs were measured. Change detections of agricultural areas in the region for years, 1983, 1995 and 2005 were conducted using Landsat Satellite images and results were compared to water levels for same years. There are two potential recharge zones for Saq aquifer in the area, both are structurally controlled. The first zone is the outlet of wadi Ar Risha basin in south-eastern corner of the study area. The second is the western water divide of wadi Turfiya basin in the North west. Results of the study also indicated that 96.4 % of the total abstraction is consumed for agriculture supply. The present abstractions exceed both recharge and safe yield of the aquifer system, thus the aquifer is overexploited and mined. The average decrease in groundwater storage during the year 1983-2005 was estimated to be 33.4 Mm3, representing an average yearly decline of 1.98 m of the water table.

  5. Joint Calibration of Submarine Groundwater Discharge (SGD) with Tidal Pumping: Modeling Variable-density Groundwater Flow in Unconfined Coastal Aquifer of Apalachee Bay, Gulf of Mexico

    Science.gov (United States)

    Li, X.; Hu, B.; Burnett, W.; Santos, I.

    2008-05-01

    Submarine Groundwater Discharge (SGD) as an unseen phenomenon is now recognized as an important pathway between land and sea. These discharges typically display significant spatial and temporal variability making quantification difficult. Groundwater seepage is patchy, diffuse, and temporally variable, and thus makes the estimation of its magnitude and components is a challenging enterprise. A two-dimensional hydrogeological model is developed to the near-shore environment of an unconfined aquifer at a Florida coastal area in the northeastern Gulf of Mexico. Intense geological survey and slug tests are set to investigate the heterogeneity of this layered aquifer. By applying SEAWAT2000, considering the uncertainties caused by changes of boundary conditions, a series of variable-density-flow models incorporates the tidal-influenced seawater recirculation and the freshwater-saltwater mixing zone under the dynamics of tidal pattern, tidal amplitude and variation of water table. These are thought as the contributing factors of tidal pumping and hydraulic gradient which are the driven forces of SGD. A tidal-influenced mixing zone in the near-shore aquifer shows the importance of tidal mechanism to flow and salt transport in the process of submarine pore water exchange. Freshwater ratio in SGD is also analyzed through the comparison of Submarine Groundwater Recharge and freshwater inflow. The joint calibration with other methods (natural tracer model and seepage meter) is also discussed.

  6. Ground-water flow in low permeability environments

    Science.gov (United States)

    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

  7. Integration of ground-water and vadose-zone geochemistry to investigate hydrochemical evolution

    International Nuclear Information System (INIS)

    Fisher, R.S.; Mullican, W.F.

    1990-01-01

    This paper summarizes the results of an extensive groundwater-sampling program conducted in the Hueco Bolson and Diablo Plateau area of West Texas. The origin, hydrochemical evolution, and age of groundwater in arid lands of Trans-Pecos Texas were investigated by combining mineralogic analyses of soils and aquifer matrix, chemical analyses of readily soluble materials in soils and water extracted from the thick, unsaturated zone, and chemical and isotopic analyses of groundwater from three principal aquifers, the Diablo Plateau, Hueco Bolson, and Rio Grande alluvial aquifers. Repeated groundwater sampling over a 3-year period and quarterly sampling of selected wells revealed no significant short-term chemical or isotopic variability. Groundwater ages range from recent to nearly 28,000 years; the distribution of ages reflects relative permeability (transmissivity) of the aquifers. Most groundwaters evolve from calcium-bicarbonate to sodium-sulfate types because of carbonate and sulfate mineral dissolution coupled with exchange of aqueous calcium and magnesium for sodium on clay minerals. Water in the Rio Grande alluvial aquifer evolved to a sodium-chloride type as a result of extensive evapotranspiration on irrigated fields. The appendices list detailed results of field measurements of temperature, pH, Eh, dissolved oxygen, and major ion concentrations

  8. Nitrate removal in a restored riparian groundwater system: functioning and importance of individual riparian zones

    Directory of Open Access Journals (Sweden)

    S. Peter

    2012-11-01

    Full Text Available For the design and the assessment of river restoration projects, it is important to know to what extent the elimination of reactive nitrogen (N can be improved in the riparian groundwater. We investigated the effectiveness of different riparian zones, characterized by a riparian vegetation succession, for nitrate (NO3 removal from infiltrating river water in a restored and a still channelized section of the river Thur, Switzerland. Functional genes of denitrification (nirS and nosZ were relatively abundant in groundwater from willow bush and mixed forest dominated zones, where oxygen concentrations remained low compared to the main channel and other riparian zones. After flood events, a substantial decline in NO3 concentration (> 50% was observed in the willow bush zone but not in the other riparian zones closer to the river. In addition, the characteristic enrichment of 15N and 18O in the residual NO3 pool (by up to 22‰ for δ15N and up to 12‰ for δ18O provides qualitative evidence that the willow bush and forest zones were sites of active denitrification and, to a lesser extent, NO3 removal by plant uptake. Particularly in the willow bush zone during a period of water table elevation after a flooding event, substantial input of organic carbon into the groundwater occurred, thereby fostering post-flood denitrification activity that reduced NO3 concentration with a rate of ~21 μmol N l−1 d−1. Nitrogen removal in the forest zone was not sensitive to flood pulses, and overall NO3 removal rates were lower (~6 μmol l−1 d−1. Hence, discharge-modulated vegetation–soil–groundwater coupling was found to be a key driver for riparian NO3 removal. We estimated that

  9. Uranium-series constraints on radionuclide transport and groundwater flow at the Nopal I uranium deposit, Sierra Pena Blanca, Mexico.

    Science.gov (United States)

    Goldstein, Steven J; Abdel-Fattah, Amr I; Murrell, Michael T; Dobson, Patrick F; Norman, Deborah E; Amato, Ronald S; Nunn, Andrew J

    2010-03-01

    Uranium-series data for groundwater samples from the Nopal I uranium ore deposit were obtained to place constraints on radionuclide transport and hydrologic processes for a nuclear waste repository located in fractured, unsaturated volcanic tuff. Decreasing uranium concentrations for wells drilled in 2003 are consistent with a simple physical mixing model that indicates that groundwater velocities are low ( approximately 10 m/y). Uranium isotopic constraints, well productivities, and radon systematics also suggest limited groundwater mixing and slow flow in the saturated zone. Uranium isotopic systematics for seepage water collected in the mine adit show a spatial dependence which is consistent with longer water-rock interaction times and higher uranium dissolution inputs at the front adit where the deposit is located. Uranium-series disequilibria measurements for mostly unsaturated zone samples indicate that (230)Th/(238)U activity ratios range from 0.005 to 0.48 and (226)Ra/(238)U activity ratios range from 0.006 to 113. (239)Pu/(238)U mass ratios for the saturated zone are 1000 times lower than the U mobility. Saturated zone mobility decreases in the order (238)U approximately (226)Ra > (230)Th approximately (239)Pu. Radium and thorium appear to have higher mobility in the unsaturated zone based on U-series data from fractures and seepage water near the deposit.

  10. 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

  11. A two-dimensional analytical well model with applications to groundwater flow and convective transport modelling in the geosphere

    International Nuclear Information System (INIS)

    Chan, T.; Nakka, B.W.

    1994-12-01

    A two-dimensional analytical well model has been developed to describe steady groundwater flow in an idealized, confined aquifer intersected by a withdrawal well. The aquifer comprises a low-dipping fracture zone. The model is useful for making simple quantitative estimates of the transport of contaminants along groundwater pathways in the fracture zone to the well from an underground source that intercepts the fracture zone. This report documents the mathematical development of the analytical well model. It outlines the assumptions and method used to derive an exact analytical solution, which is verified by two other methods. It presents expressions for calculating quantities such as streamlines (groundwater flow paths), fractional volumetric flow rates, contaminant concentration in well water and minimum convective travel time to the well. In addition, this report presents the results of applying the analytical model to a site-specific conceptual model of the Whiteshell Research Area in southeastern Manitoba, Canada. This hydrogeological model includes the presence of a 20-m-thick, low-dipping (18 deg) fracture zone (LD1) that intercepts the horizon of a hypothetical disposal vault located at a depth of 500 m. A withdrawal well intercepts LD1 between the vault level and the ground surface. Predictions based on parameters and boundary conditions specific to LD1 are presented graphically. The analytical model has specific applications in the SYVAC geosphere model (GEONET) to calculate the fraction of a plume of contaminants moving up the fracture zone that is captured by the well, and to describe the drawdown in the hydraulic head in the fracture zone caused by the withdrawal well. (author). 16 refs., 6 tabs., 35 figs

  12. Groundwater flow modeling for near-field of a hypothetical near-surface disposal facility

    International Nuclear Information System (INIS)

    Park, H. Y.; Park, J. W.; Jang, G. M.; Kim, C. R.

    2000-01-01

    For a hypothetical near-surface radioactive disposal facility, the behavior of groundwater flow around the near-field of disposal vault located at the unsaturated zone were analyzed. Three alternative conceptual models proposed as the hydraulic barrier layer design were simulated to assess the hydrologic performance of engineered barriers for the facility. In order to evaluate the seepage possibility of the infiltrated water passed through the final disposal cover after the facility closure, the flow path around and water flux through each disposal vault were compared. The hydrologic parameters variation that accounts for the long-term aging and degradation of the cover and engineered materials was considered in the simulations. The results showed that it is necessary to construct the hydraulic barrier at the upper and sides of the vault, and that, for this case, achieving design hydraulic properties of bentonite/sand mixture barrier in the as-built condition is crucial to limit the seepage into the waste

  13. In Situ Groundwater Denitrification in the Riparian Zone of a Short-Rotation Woody Crop Experimental Watershed

    Science.gov (United States)

    Jeffers, J. B.; Jackson, C. R.; Rau, B.; Pringle, C. M.; Matteson, C.

    2017-12-01

    The southeastern United States has potential to become a major producer of short rotation woody crops (SRWC) for the production of biofuels, but this will require converting to more intensive forest management practices that will increase nitrate (NO3-) loading and alter nitrogen cycling in nearby freshwater ecosystems. Water quality monitoring in an experimental short-rotation woody crop watershed in the Coastal Plain of South Carolina has shown increased concentrations of NO3- in groundwater but no evidence of increased NO3- in riparian groundwater or surface waters. Forested riparian areas established as streamside management zones (SMZ) are known to act as buffers to surface water bodies by mitigating nutrients. The objectives of this study were to quantify denitrification by measuring dinitrogen (N2) and nitrous oxide (N2O) concentrations along groundwater flow paths and analyze relationships between denitrification estimates, nutrients, and water chemistry parameters. A network of piezometers has been established in the Fourmile Experimental Watershed at the Department of Energy - Savannah River Site. Water samples were collected monthly and were analyzed for concentrations of nutrients (temperature, specific conductivity, dissolved oxygen, pH, dissolved organic carbon) and dissolved gases (N2, Ar, N2O). Preliminary data showed greater dissolved N2O concentrations than dissolved N2 concentrations in groundwater. The ratios of N2O to combined end products of denitrification (N2O / N2O+N2) ranged from 0.33 to 0.99. Mean N2O+N2 concentrations were greater in groundwater samples in the SRWC plot and along the SMZ boundary than along the ephemeral stream within the riparian zone. Correlations between water chemistry parameters and N2 concentrations are indicative of known biogeochemical driving factors of denitrification. Continued monthly sampling will be coupled with analysis of nutrient concentrations (NO3-, NH4+, TN) to help determine transport and processing

  14. 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.)

  15. 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

  16. 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.

  17. 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

  18. 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

  19. 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

  20. 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

  1. 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

  2. Unsteady Flows Control Hydrologic Turnover Rates in Antarctic Hyporheic Zones

    Science.gov (United States)

    Wlostowski, A. N.; Gooseff, M. N.; McKnight, D. M.; Lyons, W. B.; Saelens, E.

    2016-12-01

    Hydrologic turnover of the hyporheic zone (HZ) is the process of HZ flowpaths receiving water and solutes from the stream channel while simultaneously contributing water and solutes from the HZ back to the stream channel. The influence of hydrologic turnover on HZ solute storage depends on the relative magnitude of hyporheic exchange rates (i.e. physical transport) and biogeochemical reaction rates. Because both exchange rates and reaction rates are unsteady in natural systems, the availability of solutes in the HZ is controlled by the legacy of hydraulic and biological conditions. In this study, we quantify the influence of unsteady flows on hydrologic turnover of the HZ. We study a glacial melt stream in the McMurdo Dry Valleys of Antarctica (MDVs). The MDVs provide an ideal setting for investigating hydrologic and chemical storage characteristics of HZs, because nearly all streamflow is generated from glacier melt and the HZ is vertically bounded by continuous permafrost. A dense network of shallow groundwater wells and piezometers was installed along a 60-meter reach of Von Guerard Stream. 12 days of continuous water level data in each well was used to compute the magnitude and direction of 2D hydraulic gradients between the stream channel and lateral hyporheic aquifer. Piezometers were sampled daily for stable isotope abundances. The direction and magnitude of the cross-valley (CV), perpendicular to the thalweg, component of hydraulic gradients is sensitive to daily flood events and exhibits significant spatial heterogeneity. CV gradients are consistently oriented from the hyporheic aquifer towards the stream channel on 2 sections of the study reach, whereas CV gradients are consistently oriented from the stream channel towards the hyporheic aquifer on 1 section. Three sections show diel changes in orientation of CV gradients, coincident with the passage of daily flood events. During a 4-day period of low flows, the HZ is isotopically distinct from the stream

  3. 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

  4. 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.

  5. Response to recharge variation of thin rainwater lenses and their mixing zone with underlying saline groundwater

    Directory of Open Access Journals (Sweden)

    S. Eeman

    2012-10-01

    Full Text Available In coastal zones with saline groundwater, fresh groundwater lenses may form due to infiltration of rain water. The thickness of both the lens and the mixing zone, determines fresh water availability for plant growth. Due to recharge variation, the thickness of the lens and the mixing zone are not constant, which may adversely affect agricultural and natural vegetation if saline water reaches the root zone during the growing season. In this paper, we study the response of thin lenses and their mixing zone to variation of recharge. The recharge is varied using sinusoids with a range of amplitudes and frequencies. We vary lens characteristics by varying the Rayleigh number and Mass flux ratio of saline and fresh water, as these dominantly influence the thickness of thin lenses and their mixing zone. Numerical results show a linear relation between the normalised lens volume and the main lens and recharge characteristics, enabling an empirical approximation of the variation of lens thickness. Increase of the recharge amplitude causes increase and the increase of recharge frequency causes a decrease in the variation of lens thickness. The average lens thickness is not significantly influenced by these variations in recharge, contrary to the mixing zone thickness. The mixing zone thickness is compared to that of a Fickian mixing regime. A simple relation between the travelled distance of the centre of the mixing zone position due to variations in recharge and the mixing zone thickness is shown to be valid for both a sinusoidal recharge variation and actual records of daily recharge data. Starting from a step response function, convolution can be used to determine the effect of variable recharge in time. For a sinusoidal curve, we can determine delay of lens movement compared to the recharge curve as well as the lens amplitude, derived from the convolution integral. Together the proposed equations provide us with a first order approximation of lens

  6. Vinasse application to sugar cane fields. Effect on the unsaturated zone and groundwater at Valle del Cauca (Colombia).

    Science.gov (United States)

    Ortegón, Gloria Páez; Arboleda, Fernando Muñoz; Candela, Lucila; Tamoh, Karim; Valdes-Abellan, Javier

    2016-01-01

    Extensive application of vinasse, a subproduct from sugar cane plantations for bioethanol production, is currently taking place as a source of nutrients that forms part of agricultural management in different agroclimatic regions. Liquid vinasse composition is characterised by high variability of organic compounds and major ions, acid pH (4.7), high TDS concentration (117,416-599,400mgL(-1)) and elevated EC (14,350-64,099μScm(-1)). A large-scale sugar cane field application is taking place in Valle del Cauca (Colombia), where monitoring of soil, unsaturated zone and the aquifer underneath has been made since 2006 to evaluate possible impacts on three experimental plots. For this assessment, monitoring wells and piezometers were installed to determine groundwater flow and water samples were collected for chemical analysis. In the unsaturated zone, tensiometers were installed at different depths to determine flow patterns, while suction lysimeters were used for water sample chemical determinations. The findings show that in the sandy loam plot (Hacienda Real), the unsaturated zone is characterised by low water retention, showing a high transport capacity, while the other two plots of silty composition presented temporal saturation due to La Niña event (2010-2011). The strong La Niña effect on aquifer recharge which would dilute the infiltrated water during the monitoring period and, on the other hand dissolution of possible precipitated salts bringing them back into solution may occur. A slight increase in the concentration of major ions was observed in groundwater (~5% of TDS), which can be attributed to a combination of factors: vinasse dilution produced by water input and hydrochemical processes along with nutrient removal produced by sugar cane uptake. This fact may make the aquifer vulnerable to contamination. Copyright © 2015 Elsevier B.V. All rights reserved.

  7. Regional variability of nitrate fluxes in the unsaturated zone and groundwater, Wisconsin, USA

    Science.gov (United States)

    Green, Christopher T.; Liao, Lixia; Nolan, Bernard T.; Juckem, Paul F.; Shope, Christopher L.; Tesoriero, Anthony J.; Jurgens, Bryant

    2018-01-01

    Process-based modeling of regional NO3− fluxes to groundwater is critical for understanding and managing water quality, but the complexity of NO3− reactive transport processes make implementation a challenge. This study introduces a regional vertical flux method (VFM) for efficient estimation of reactive transport of NO3− in the vadose zone and groundwater. The regional VFM was applied to 443 well samples in central-eastern Wisconsin. Chemical measurements included O2, NO3−, N2 from denitrification, and atmospheric tracers of groundwater age including carbon-14, chlorofluorocarbons, tritium, and tritiogenic helium. VFM results were consistent with observed chemistry, and calibrated parameters were in-line with estimates from previous studies. Results indicated that (1) unsaturated zone travel times were a substantial portion of the transit time to wells and streams (2) since 1945 fractions of applied N leached to groundwater have increased for manure-N, possibly due to increased injection of liquid manure, and decreased for fertilizer-N, and (3) under current practices and conditions, approximately 60% of the shallow aquifer will eventually be affected by downward migration of NO3−, with denitrification protecting the remaining 40%. Recharge variability strongly affected the unsaturated zone lag times and the eventual depth of the NO3− front. Principal components regression demonstrated that VFM parameters and predictions were significantly correlated with hydrogeochemical landscape features. The diverse and sometimes conflicting aspects of N management (e.g. limiting N volatilization versus limiting N losses to groundwater) warrant continued development of large-scale holistic strategies to manage water quality and quantity.

  8. Regional Variability of Nitrate Fluxes in the Unsaturated Zone and Groundwater, Wisconsin, USA

    Science.gov (United States)

    Green, Christopher T.; Liao, Lixia; Nolan, Bernard T.; Juckem, Paul F.; Shope, Christopher L.; Tesoriero, Anthony J.; Jurgens, Bryant C.

    2018-01-01

    Process-based modeling of regional NO3- fluxes to groundwater is critical for understanding and managing water quality, but the complexity of NO3- reactive transport processes makes implementation a challenge. This study introduces a regional vertical flux method (VFM) for efficient estimation of reactive transport of NO3- in the vadose zone and groundwater. The regional VFM was applied to 443 well samples in central-eastern Wisconsin. Chemical measurements included O2, NO3-, N2 from denitrification, and atmospheric tracers of groundwater age including carbon-14, chlorofluorocarbons, tritium, and tritiogenic helium. VFM results were consistent with observed chemistry, and calibrated parameters were in-line with estimates from previous studies. Results indicated that (1) unsaturated zone travel times were a substantial portion of the transit time to wells and streams, (2) since 1945 fractions of applied N leached to groundwater have increased for manure-N, possibly due to increased injection of liquid manure, and decreased for fertilizer-N, and (3) under current practices and conditions, approximately 60% of the shallow aquifer will eventually be affected by downward migration of NO3-, with denitrification protecting the remaining 40%. Recharge variability strongly affected the unsaturated zone lag times and the eventual depth of the NO3- front. Principal components regression demonstrated that VFM parameters and predictions were significantly correlated with hydrogeochemical landscape features. The diverse and sometimes conflicting aspects of N management (e.g., limiting N volatilization versus limiting N losses to groundwater) warrant continued development of large-scale holistic strategies to manage water quality and quantity.

  9. Water-Level Data Analysis for the Saturated Zone Site-Scale Flow and Transport Model

    International Nuclear Information System (INIS)

    Tucci, P.

    2001-01-01

    This Analysis/Model Report (AMR) documents an updated analysis of water-level data performed to provide the saturated-zone, site-scale flow and transport model (CRWMS M and O 2000) with the configuration of the potentiometric surface, target water-level data, and hydraulic gradients for model calibration. The previous analysis was presented in ANL-NBS-HS-000034, Rev 00 ICN 01, Water-Level Data Analysis for the Saturated Zone Site-Scale Flow and Transport Model (USGS 2001). This analysis is designed to use updated water-level data as the basis for estimating water-level altitudes and the potentiometric surface in the SZ site-scale flow and transport model domain. The objectives of this revision are to develop computer files containing (1) water-level data within the model area (DTN: GS010908312332.002), (2) a table of known vertical head differences (DTN: GS0109083 12332.003), and (3) a potentiometric-surface map (DTN: GS010608312332.001) using an alternate concept from that presented in ANL-NBS-HS-000034, Rev 00 ICN 01 for the area north of Yucca Mountain. The updated water-level data include data obtained from the Nye County Early Warning Drilling Program (EWDP) and data from borehole USW WT-24. In addition to being utilized by the SZ site-scale flow and transport model, the water-level data and potentiometric-surface map contained within this report will be available to other government agencies and water users for ground-water management purposes. The potentiometric surface defines an upper boundary of the site-scale flow model, as well as provides information useful to estimation of the magnitude and direction of lateral ground-water flow within the flow system. Therefore, the analysis documented in this revision is important to SZ flow and transport calculations in support of total system performance assessment

  10. Groundwater Recharge and Flow Processes in Taihang Mountains, a Semi-humid Region, North China

    Science.gov (United States)

    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

  11. Evaluating Contaminant Flux from the Vadose Zone to the Groundwater in the Hanford Central Plateau. SX Tank Farms Case Study

    Energy Technology Data Exchange (ETDEWEB)

    Truex, Michael J. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Oostrom, Martinus [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Last, George V. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Strickland, Christopher E. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Tartakovsky, Guzel D. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2015-09-01

    At the DOE Hanford Site, contaminants were discharged to the subsurface through engineered waste sites in the Hanford Central Plateau. Additional waste was released through waste storage tank leaks. Much of the contaminant inventory is still present within the unsaturated vadose zone sediments. The nature and extent of future groundwater contaminant plumes and the growth or decline of current groundwater plumes beneath the Hanford Central Plateau are a function of the contaminant flux from the vadose zone to the groundwater. In general, contaminant transport is slow through the vadose zone and it is difficult to directly measure contaminant flux in the vadose zone. Predictive analysis, supported by site characterization and monitoring data, was applied using a structured, systems-based approach to estimate the future contaminant flux to groundwater in support of remediation decisions for the vadose zone and groundwater (Truex and Carroll 2013). The SX Tank Farm was used as a case study because of the existing contaminant inventory in the vadose zone, observations of elevated moisture content in portions of the vadose zone, presence of a limited-extent groundwater plume, and the relatively large amount and wide variety of data available for the site. Although the SX Tank Farm case study is most representative of conditions at tank farm sites, the study has elements that are also relevant to other types of disposal sites in the Hanford Central Plateau.

  12. Modeling unsaturated-zone flow at Rainier Mesa as a possible analog for a future Yucca Mountain

    International Nuclear Information System (INIS)

    Gauthier, J.H.

    1998-01-01

    Rainier Mesa is structurally similar to Yucca Mountain, and receives precipitation similar to the estimated long-term average for Yucca Mountain. Tunnels through the unsaturated zone at Rainier Mesa have encountered perched water and, after the perched water was drained, flow in fractures and faults. Although flow observations have been primarily qualitative, Rainier Mesa hydrology is a potential analog for Yucca Mountain hydrology in a wetter climate. In this paper, a groundwater flow model that has been used in the performance assessment of Yucca Mountain--the weeps model--is applied to Rainier Mesa. The intent is to gain insight in both Rainier Mesa and the weeps flow model

  13. 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

  14. Flow of groundwater from great depths into the near surface deposits - modelling of a local domain in northeast Uppland

    International Nuclear Information System (INIS)

    Holmen, Johan G.; Forsman, Jonas

    2005-01-01

    these areas do not vary much for different values of the permeability of the uppermost part of the flow medium or for the applied different values of groundwater recharge. Flow paths were released on-shore inside of the shore line (no paths were released below the sea) and at an approximate repository depth (i.e. 420 m), the flow paths will either discharge into the sea (i.e. 34%) or above the sea (i.e. 66%). Considering the discharge areas above the sea, nearly all of the flow paths from repository depth will discharge into lakes, and especially where a fracture zones intersects a lake. Considering a lake with a thick layer of low-permeable sediments at the base of the lake (a large flow-resistance), for such a situation nearly all flow paths discharges along the lake perimeter where no sediments occur. And for a situation in which a lake has sediments of small resistance along its base, for such a situation most flow paths discharge at the base of the lake through the lake sediments. Most flow routes from repository depths demonstrate short path lengths in the quaternary deposits. Only a small percentage (< 5%) of the flow paths demonstrate path lengths in the surface near material (in the uppermost 1.5 m of quaternary deposits) that are longer than about 50 m. This is because most flow paths from great depth flow towards lakes and other strong sinks, and reaches these areas from deep below and hence the surface near part of the flow paths will be short. Nevertheless, a small amount of flow paths (less than approximately 5% of all paths) demonstrate lengths between 50 m and 250 m in the quaternary deposits below lakes, that is however for a situation in which the resistances of the lake sediments are large. Outside of the lakes, the lengths of the studied flow paths in the quaternary deposits tend to be shorter and are not much influenced by the resistance of the lake sediments. For most flow paths from great depth, the total break through times depend very strongly

  15. Flow of groundwater from great depths into the near surface deposits - modelling of a local domain in northeast Uppland

    Energy Technology Data Exchange (ETDEWEB)

    Holmen, Johan G.; Forsman, Jonas [Golder Associates, Stockholm (Sweden)

    2005-01-15

    these areas do not vary much for different values of the permeability of the uppermost part of the flow medium or for the applied different values of groundwater recharge. Flow paths were released on-shore inside of the shore line (no paths were released below the sea) and at an approximate repository depth (i.e. 420 m), the flow paths will either discharge into the sea (i.e. 34%) or above the sea (i.e. 66%). Considering the discharge areas above the sea, nearly all of the flow paths from repository depth will discharge into lakes, and especially where a fracture zones intersects a lake. Considering a lake with a thick layer of low-permeable sediments at the base of the lake (a large flow-resistance), for such a situation nearly all flow paths discharges along the lake perimeter where no sediments occur. And for a situation in which a lake has sediments of small resistance along its base, for such a situation most flow paths discharge at the base of the lake through the lake sediments. Most flow routes from repository depths demonstrate short path lengths in the quaternary deposits. Only a small percentage (< 5%) of the flow paths demonstrate path lengths in the surface near material (in the uppermost 1.5 m of quaternary deposits) that are longer than about 50 m. This is because most flow paths from great depth flow towards lakes and other strong sinks, and reaches these areas from deep below and hence the surface near part of the flow paths will be short. Nevertheless, a small amount of flow paths (less than approximately 5% of all paths) demonstrate lengths between 50 m and 250 m in the quaternary deposits below lakes, that is however for a situation in which the resistances of the lake sediments are large. Outside of the lakes, the lengths of the studied flow paths in the quaternary deposits tend to be shorter and are not much influenced by the resistance of the lake sediments. For most flow paths from great depth, the total break through times depend very strongly

  16. Unintentional contaminant transfer from groundwater to the vadose zone during source zone remediation of volatile organic compounds.

    Science.gov (United States)

    Chong, Andrea D; Mayer, K Ulrich

    2017-09-01

    Historical heavy use of chlorinated solvents in conjunction with improper disposal practices and accidental releases has resulted in widespread contamination of soils and groundwater in North America and worldwide. As a result, remediation of chlorinated solvents is required at many sites. For source zone treatment, common remediation strategies include in-situ chemical oxidation (ISCO) using potassium or sodium permanganate, and the enhancement of biodegradation by primary substrate addition. It is well known that these remediation methods tend to generate gas (carbon dioxide (CO 2 ) in the case of ISCO using permanganate, CO 2 and methane (CH 4 ) in the case of bioremediation). Vigorous gas generation in the presence of chlorinated solvents, which are categorized as volatile organic contaminants (VOCs), may cause gas exsolution, ebullition and stripping of the contaminants from the treatment zone. This process may lead to unintentional 'compartment transfer', whereby VOCs are transported away from the contaminated zone into overlying clean sediments and into the vadose zone. To this extent, benchtop column experiments were conducted to quantify the effect of gas generation during remediation of the common chlorinated solvent trichloroethylene (TCE/C 2 Cl 3 H). Both ISCO and enhanced bioremediation were considered as treatment methods. Results show that gas exsolution and ebullition occurs for both remediation technologies. Facilitated by ebullition, TCE was transported from the source zone into overlying clean groundwater and was subsequently released into the column headspace. For the case of enhanced bioremediation, the intermediate degradation product vinyl chloride (VC) was also stripped from the treatment zone. The concentrations measured in the headspace of the columns (TCE ∼300ppm in the ISCO column, TCE ∼500ppm and VC ∼1380ppm in the bioremediation column) indicate that substantial transfer of VOCs to the vadose zone is possible. These findings

  17. STRING 3: An Advanced Groundwater Flow Visualization Tool

    Science.gov (United States)

    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

  18. Environmental isotope study related to groundwater age, flow system and saline water origin in Quaternary aquifers of North China Plain

    International Nuclear Information System (INIS)

    Zhang Zhigan; Payne, B.R.

    1988-01-01

    An isotopic hydrology section across the North China Plain has been studied to investigate problems of groundwater age, flow system and saline water origin in a semi-arid pre-mountain artesian basin. Two local and one regional flow system along the section have been recognized. Turnover time of water for alluvial fan, shallow and regional systems are estimated to be the order of 10 2 , 10 3 , and 10 4 years respectively. Specific flow rates for the three systems have been calculated. Only less than 5 percent of flow from alluvial fan is drained by the regional flow system and the rest, in natural conditions, discharges at surface in the front edge of an alluvial fan and forms a groundwater discharge belt at a good distance away from the mountain foot. Developed in the alluvial plain and coastal plain areas the shallow flow system embraces a series of small local systems. Groundwater in these systems appears to be the salt carrier during continental salinization. It washes salt out of the recharge area and deep-occurred strata by circulating and carries it up to the surface in lowland areas. Consequently, in parallel with salinization at surface a desalinization process occurs at depth, which provides an additional explanation for the existing thick deep fresh water zone in most arid and semi-arid regions, where continental salting process is in progress. (author). 6 refs, 8 figs, 4 tabs

  19. Water-Level Data Analysis for the Saturated Zone Site-Scale Flow and Transport Model

    International Nuclear Information System (INIS)

    K. Rehfeldt

    2004-01-01

    This report is an updated analysis of water-level data performed to provide the ''Saturated Zone Site-Scale Flow Model'' (BSC 2004 [DIRS 170037]) (referred to as the saturated zone (SZ) site-scale flow model or site-scale SZ flow model in this report) with the configuration of the potentiometric surface, target water-level data, and hydraulic gradients for calibration of groundwater flow models. This report also contains an expanded discussion of uncertainty in the potentiometric-surface map. The analysis of the potentiometric data presented in Revision 00 of this report (USGS 2001 [DIRS 154625]) provides the configuration of the potentiometric surface, target heads, and hydraulic gradients for the calibration of the SZ site-scale flow model (BSC 2004 [DIRS 170037]). Revision 01 of this report (USGS 2004 [DIRS 168473]) used updated water-level data for selected wells through the year 2000 as the basis for estimating water-level altitudes and the potentiometric surface in the SZ site-scale flow and transport model domain based on an alternative interpretation of perched water conditions. That revision developed computer files containing: Water-level data within the model area (DTN: GS010908312332.002); A table of known vertical head differences (DTN: GS010908312332.003); and A potentiometric-surface map (DTN: GS010608312332.001) using an alternative concept from that presented by USGS (2001 [DIRS 154625]) for the area north of Yucca Mountain. The updated water-level data presented in USGS (2004 [DIRS 168473]) include data obtained from the Nye County Early Warning Drilling Program (EWDP) Phases I and II and data from Borehole USW WT-24. This document is based on Revision 01 (USGS 2004 [DIRS 168473]) and expands the discussion of uncertainty in the potentiometric-surface map. This uncertainty assessment includes an analysis of the impact of more recent water-level data and the impact of adding data from the EWDP Phases III and IV wells. In addition to being utilized

  20. Water-Level Data Analysis for the Saturated Zone Site-Scale Flow and Transport Model

    Energy Technology Data Exchange (ETDEWEB)

    K. Rehfeldt

    2004-10-08

    This report is an updated analysis of water-level data performed to provide the ''Saturated Zone Site-Scale Flow Model'' (BSC 2004 [DIRS 170037]) (referred to as the saturated zone (SZ) site-scale flow model or site-scale SZ flow model in this report) with the configuration of the potentiometric surface, target water-level data, and hydraulic gradients for calibration of groundwater flow models. This report also contains an expanded discussion of uncertainty in the potentiometric-surface map. The analysis of the potentiometric data presented in Revision 00 of this report (USGS 2001 [DIRS 154625]) provides the configuration of the potentiometric surface, target heads, and hydraulic gradients for the calibration of the SZ site-scale flow model (BSC 2004 [DIRS 170037]). Revision 01 of this report (USGS 2004 [DIRS 168473]) used updated water-level data for selected wells through the year 2000 as the basis for estimating water-level altitudes and the potentiometric surface in the SZ site-scale flow and transport model domain based on an alternative interpretation of perched water conditions. That revision developed computer files containing: Water-level data within the model area (DTN: GS010908312332.002); A table of known vertical head differences (DTN: GS010908312332.003); and A potentiometric-surface map (DTN: GS010608312332.001) using an alternative concept from that presented by USGS (2001 [DIRS 154625]) for the area north of Yucca Mountain. The updated water-level data presented in USGS (2004 [DIRS 168473]) include data obtained from the Nye County Early Warning Drilling Program (EWDP) Phases I and II and data from Borehole USW WT-24. This document is based on Revision 01 (USGS 2004 [DIRS 168473]) and expands the discussion of uncertainty in the potentiometric-surface map. This uncertainty assessment includes an analysis of the impact of more recent water-level data and the impact of adding data from the EWDP Phases III and IV wells. In

  1. Appraising options to reduce shallow groundwater tables and enhance flow conditions over regional scales in an irrigated alluvial aquifer system

    Science.gov (United States)

    Morway, Eric D.; Gates, Timothy K.; Niswonger, Richard G.

    2013-01-01

    Some of the world’s key agricultural production systems face big challenges to both water quantity and quality due to shallow groundwater that results from long-term intensive irrigation, namely waterlogging and salinity, water losses, and environmental problems. This paper focuses on water quantity issues, presenting finite-difference groundwater models developed to describe shallow water table levels, non-beneficial groundwater consumptive use, and return flows to streams across two regions within an irrigated alluvial river valley in southeastern Colorado, USA. The models are calibrated and applied to simulate current baseline conditions in the alluvial aquifer system and to examine actions for potentially improving these conditions. The models provide a detailed description of regional-scale subsurface unsaturated and saturated flow processes, thereby enabling detailed spatiotemporal description of groundwater levels, recharge to infiltration ratios, partitioning of ET originating from the unsaturated and saturated zones, and groundwater flows, among other variables. Hybrid automated and manual calibration of the models is achieved using extensive observations of groundwater hydraulic head, groundwater return flow to streams, aquifer stratigraphy, canal seepage, total evapotranspiration, the portion of evapotranspiration supplied by upflux from the shallow water table, and irrigation flows. Baseline results from the two regional-scale models are compared to model predictions under variations of four alternative management schemes: (1) reduced seepage from earthen canals, (2) reduced irrigation applications, (3) rotational lease fallowing (irrigation water leased to municipalities, resulting in temporary dry-up of fields), and (4) combinations of these. The potential for increasing the average water table depth by up to 1.1 and 0.7 m in the two respective modeled regions, thereby reducing the threat of waterlogging and lowering non-beneficial consumptive use

  2. 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

  3. 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

  4. Sensitivity Analysis for Steady State Groundwater Flow Using Adjoint Operators

    Science.gov (United States)

    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.

  5. A coupled groundwater-flow-modelling and vulnerability-mapping methodology for karstic terrain management

    Science.gov (United States)

    Kavouri, Konstantina P.; Karatzas, George P.; Plagnes, Valérie

    2017-08-01

    A coupled groundwater-flow-modelling and vulnerability-mapping methodology for the management of karst aquifers with spatial variability is developed. The methodology takes into consideration the duality of flow and recharge in karst and introduces a simple method to integrate the effect of temporal storage in the unsaturated zone. In order to investigate the applicability of the developed methodology, simulation results are validated against available field measurement data. The criteria maps from the PaPRIKa vulnerability-mapping method are used to document the groundwater flow model. The FEFLOW model is employed for the simulation of the saturated zone of Palaikastro-Chochlakies karst aquifer, in the island of Crete, Greece, for the hydrological years 2010-2012. The simulated water table reproduces typical karst characteristics, such as steep slopes and preferred drain axes, and is in good agreement with field observations. Selected calculated error indicators—Nash-Sutcliffe efficiency (NSE), root mean squared error (RMSE) and model efficiency (E')—are within acceptable value ranges. Results indicate that different storage processes take place in different parts of the aquifer. The north-central part seems to be more sensitive to diffuse recharge, while the southern part is affected primarily by precipitation events. Sensitivity analysis is performed on the parameters of hydraulic conductivity and specific yield. The methodology is used to estimate the feasibility of artificial aquifer recharge (AAR) at the study area. Based on the developed methodology, guidelines were provided for the selection of the appropriate AAR scenario that has positive impact on the water table.

  6. Numerical simulation of groundwater flow for the Yakima River basin aquifer system, Washington

    Science.gov (United States)

    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.

  7. Neural Network approach to assess the thermal affected zone around the injection well in a groundwater heat pump system

    Science.gov (United States)

    Lo Russo, Stefano; Taddia, Glenda; Verda, Vittorio

    2014-05-01

    The common use of well doublets for groundwater-sourced heating or cooling results in a thermal plume of colder or warmer re-injected groundwater known as the Thermal Affected Zone(TAZ). The plumes may be regarded either as a potential anthropogenic geothermal resource or as pollution, depending on downstream aquifer usage. A fundamental aspect in groundwater heat pump (GWHP) plant design is the correct evaluation of the thermally affected zone that develops around the injection well. Temperature anomalies are detected through numerical methods. Crucial elements in the process of thermal impact assessment are the sizes of installations, their position, the heating/cooling load of the building, and the temperature drop/increase imposed on the re-injected water flow. For multiple-well schemes, heterogeneous aquifers, or variable heating and cooling loads, numerical models that simulate groundwater and heat transport are needed. These tools should consider numerous scenarios obtained considering different heating/cooling loads, positions, and operating modes. Computational fluid dynamic (CFD) models are widely used in this field because they offer the opportunity to calculate the time evolution of the thermal plume produced by a heat pump, depending on the characteristics of the subsurface and the heat pump. Nevertheless, these models require large computational efforts, and therefore their use may be limited to a reasonable number of scenarios. Neural networks could represent an alternative to CFD for assessing the TAZ under different scenarios referring to a specific site. The use of neural networks is proposed to determine the time evolution of the groundwater temperature downstream of an installation as a function of the possible utilization profiles of the heat pump. The main advantage of neural network modeling is the possibility of evaluating a large number of scenarios in a very short time, which is very useful for the preliminary analysis of future multiple

  8. Regional Groundwater Flow Assessment in a Prospective High-Level Radioactive Waste Repository of China

    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.

  9. ENVIRONMENTAL RESEARCH BRIEF : ANALYTIC ELEMENT MODELING OF GROUND-WATER FLOW AND HIGH PERFORMANCE COMPUTING

    Science.gov (United States)

    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 ...

  10. A saturated zone site-scale flow model for Yucca mountain

    Energy Technology Data Exchange (ETDEWEB)

    Eddebbarh, Al Aziz [Los Alamos National Laboratory

    2008-01-01

    A saturated zone site-scale flow model (YMSZFM) was developed for licensing requirements for the Yucca Mountain nuclear waste repository to incorporate recent data and analyses including recent stratigraphic and water-level data from Nye County wells, single-and multiple-well hydraulic testing data, and recent hydrochemistry data. Analyses include use of data from the 2004 transient Death Valley Regional (ground-water) Flow System (DVRFS) model, the 2003 unsaturated zone flow model, and the latest hydrogeologic framework model (HFM). This model includes: (1) the latest understanding of SZ flow, (2) enhanced model validation and uncertainty analyses, (3) improved locations and definitions of fault zones, (4) refined grid resolution (500-to 250-m grid spacing), and (5) use of new data. The flow model was completed using the three-dimensional, Finite-Element Heat and Mass Transfer computer code (FEHM). The SZ site-scale flow model was calibrated with the commercial parameter estimation code, PEST to achieve a minimum difference between observed water levels and predicted water levels, and also between volumetric/mass flow rates along specific boundary segments as supplied by the DVRFS. A total of 161 water level and head measurements with varied weights were used for calibration. A comparison between measured water-level data and the potentiometric surface yielded an RMSE of 20.7 m (weighted RMSE of 8.8 m). The calibrated model was used to generate flow paths and specific discharge predictions. Model confidence was built by comparing: (l) calculated to observed hydraulic heads, and (2) calibrated to measured permeabilities (and therefore specific discharge). In addition, flowpaths emanating from below the repository footprint are consistent with those inferred both from gradients of measured head and from independent water-chemistry data. Uncertainties in the SZ site-scale flow model were quantified because all uncertainty contributes to inaccuracy in system

  11. A saturated zone site-scale flow model for Yucca Mountain

    International Nuclear Information System (INIS)

    Eddebbarh, Al Aziz

    2008-01-01

    A saturated zone site-scale flow model (YMSZFM) was developed for licensing requirements for the Yucca Mountain nuclear waste repository to incorporate recent data and analyses including recent stratigraphic and water-level data from Nye County wells, single-and multiple-well hydraulic testing data, and recent hydrochemistry data. Analyses include use of data from the 2004 transient Death Valley Regional (ground-water) Flow System (DVRFS) model, the 2003 unsaturated zone flow model, and the latest hydrogeologic framework model (HFM). This model includes: (1) the latest understanding of SZ flow, (2) enhanced model validation and uncertainty analyses, (3) improved locations and definitions of fault zones, (4) refined grid resolution (500-to 250-m grid spacing), and (5) use of new data. The flow model was completed using the three-dimensional, Finite-Element Heat and Mass Transfer computer code (FEHM). The SZ site-scale flow model was calibrated with the commercial parameter estimation code, PEST to achieve a minimum difference between observed water levels and predicted water levels, and also between volumetric/mass flow rates along specific boundary segments as supplied by the DVRFS. A total of 161 water level and head measurements with varied weights were used for calibration. A comparison between measured water-level data and the potentiometric surface yielded an RMSE of 20.7 m (weighted RMSE of 8.8 m). The calibrated model was used to generate flow paths and specific discharge predictions. Model confidence was built by comparing: (l) calculated to observed hydraulic heads, and (2) calibrated to measured permeabilities (and therefore specific discharge). In addition, flowpaths emanating from below the repository footprint are consistent with those inferred both from gradients of measured head and from independent water-chemistry data. Uncertainties in the SZ site-scale flow model were quantified because all uncertainty contributes to inaccuracy in system

  12. Three-dimensional numerical modeling of the influence of faults on groundwater flow at Yucca Mountain, Nevada

    Energy Technology Data Exchange (ETDEWEB)

    Cohen, Andrew J.B. [Univ. of California, Berkeley, CA (United States)

    1999-06-01

    Numerical simulations of groundwater flow at Yucca Mountain, Nevada are used to investigate how the faulted hydrogeologic structure influences groundwater flow from a proposed high-level nuclear waste repository. Simulations are performed using a 3-D model that has a unique grid block discretization to accurately represent the faulted geologic units, which have variable thicknesses and orientations. Irregular grid blocks enable explicit representation of these features. 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 displacement varies along strike. In addition, the presence of altered fault zones is explicitly modeled, as appropriate. The model has 23 layers and 11 faults, and approximately 57,000 grid blocks and 200,000 grid block connections. In the past, field measurement of upward vertical head gradients and high water table temperatures near faults were interpreted as indicators of upwelling from a deep carbonate aquifer. Simulations show, however, that these features can be readily explained by the geometry of hydrogeologic layers, the variability of layer permeabilities and thermal conductivities, and by the presence of permeable fault zones or faults with displacement only. In addition, a moderate water table gradient can result from fault displacement or a laterally continuous low permeability fault zone, but not from a high permeability fault zone, as others postulated earlier. 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 due to groundwater flow into areas with minimal fault displacement. Contaminants originating at the water table can flow in a direction significantly different than that of the water table gradient, and isolated

  13. Three-dimensional numerical modeling of the influence of faults on groundwater flow at Yucca Mountain, Nevada

    International Nuclear Information System (INIS)

    Cohen, Andrew J.B.

    1999-01-01

    Numerical simulations of groundwater flow at Yucca Mountain, Nevada are used to investigate how the faulted hydrogeologic structure influences groundwater flow from a proposed high-level nuclear waste repository. Simulations are performed using a 3-D model that has a unique grid block discretization to accurately represent the faulted geologic units, which have variable thicknesses and orientations. Irregular grid blocks enable explicit representation of these features. 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 displacement varies along strike. In addition, the presence of altered fault zones is explicitly modeled, as appropriate. The model has 23 layers and 11 faults, and approximately 57,000 grid blocks and 200,000 grid block connections. In the past, field measurement of upward vertical head gradients and high water table temperatures near faults were interpreted as indicators of upwelling from a deep carbonate aquifer. Simulations show, however, that these features can be readily explained by the geometry of hydrogeologic layers, the variability of layer permeabilities and thermal conductivities, and by the presence of permeable fault zones or faults with displacement only. In addition, a moderate water table gradient can result from fault displacement or a laterally continuous low permeability fault zone, but not from a high permeability fault zone, as others postulated earlier. 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 due to groundwater flow into areas with minimal fault displacement. Contaminants originating at the water table can flow in a direction significantly different than that of the water table gradient, and isolated

  14. Development and application of groundwater flow meter in fractured rocks: Measurement of velocity and direction of groundwater flow in single well

    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)

  15. 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

  16. 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.

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

    Science.gov (United States)

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

    2010-01-01

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

  18. Degradation of ground ice in a changing climate: the potential impact of groundwater flow

    Science.gov (United States)

    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

  19. Groundwater flow in a relatively old oceanic volcanic island: The Betancuria area, Fuerteventura Island, Canary Islands, Spain

    Energy Technology Data Exchange (ETDEWEB)

    Herrera, Christian, E-mail: cherrera@ucn.cl [Universidad Católica del Norte, Av. Angamos 0610, Antofagasta (Chile); Custodio, Emilio [Department of Geo-Engineering, Technical University of Catalonia (UPC), Barcelona (Spain)

    2014-10-15

    The island of Fuerteventura is the oldest of the Canary Islands' volcanic archipelago. It is constituted by volcanic submarine and subaerial activity and intrusive Miocene events, with some residual later volcanism and Quaternary volcanic deposits that have favored groundwater recharge. The climate is arid, with an average rainfall that barely attains 60 mm/year in the coast and up to 200 mm/year in the highlands. The aquifer recharge is small but significant; it is brackish due to large airborne atmospheric salinity, between 7 and 15 g m{sup −2} year{sup −1} of chloride deposition, and high evapo-concentration in the soil. The average recharge is estimated to be less than about 5 mm/year at low altitude and up to 10 mm/year in the highlands, and up to 20 mm/year associated to recent lava fields. Hydrochemical and water isotopic studies, supported by water table data and well and borehole descriptions, contribute a preliminary conceptual model of groundwater flow and water origin in the Betancuria area, the central area of the island. In general, water from springs and shallow wells tends to be naturally brackish and of recent origin. Deep saline groundwater is found and is explained as remnants of very old marine water trapped in isolated features in the very low permeability intrusive rocks. Preliminary radiocarbon dating indicates that this deep groundwater has an apparent age of less than 5000 years BP but it is the result of mixing recent water recharge with very old deep groundwater. Most of the groundwater flow occurs through the old raised volcanic shield of submarine and subaerial formations and later Miocene subaerial basalts. Groundwater transit time through the unsaturated zone is of a few decades, which allows the consideration of long-term quasi-steady state recharge. Transit times are up to a few centuries through the saturated old volcanics and up to several millennia in the intrusive formations, where isolated pockets of very old water may

  20. 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

  1. Groundwater flow processes and mixing in active volcanic systems: the case of Guadalajara (Mexico)

    Science.gov (United States)

    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

  2. Characteristic groundwater level regimes in the capture zones of radial collector wells and importance of identification (Case study of Belgrade Groundwater Source

    Directory of Open Access Journals (Sweden)

    Božović Đorđije

    2016-01-01

    Full Text Available Assessment of the operating modes of radial collector wells reveals that the pumping levels in the well caissons are very low relative to the depth/elevation of the laterals, which is a common occurrence at Belgrade Groundwater Source. As a result, well discharge capacities vary over a broad range and groundwater levels in the capture zones differ even when the rate of discharge is the same. Five characteristic groundwater level regimes are identified and their origin is analyzed using representative wells as examples. The scope and type of background information needed to identify the groundwater level regime are presented and an interpretation approach is proposed for preliminary assessment of the aquifer potential at the well site for providing the needed amount of groundwater. [Projekat Ministarstva nauke Republike Srbije, br. OI176022, br. TR33039 i br. III43004

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

    Science.gov (United States)

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

    2013-01-01

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

  4. Summary of Vadose -- Zone Conceptual Models for Flow and Contaminant Transport and 1999 - 2003 Progress on Resolving Deficiencies in Understanding the Vadose Zone at the INEEL

    Energy Technology Data Exchange (ETDEWEB)

    Robert C. Starr; Dana L. Dettmers; Brennon R. Orr; Thomas R. Wood

    2003-12-01

    The thick vadose zone that underlies the Idaho National Engineering and Environmental Laboratory has been recognized both as an avenue through which contaminants disposed at or near the ground surface can migrate to groundwater in the underlying Eastern Snake River Plain aquifer, and as a barrier to the movement of contaminants into the aquifer. Flow and contaminant transport in the vadose zone at the INEEL is complicated by the highly heterogeneous nature of the geologic framework and by the variations in the behavior of different contaminants in the subsurface. The state of knowledge concerning flow and contaminant transport in the vadose zone at and near the INEEL IN 1999 was summarized in Deficiencies in Vadose Zone Understanding at the Idaho National Engineering and Environmental Laboratory (Wood et al., 2000). These authors identified deficiencies in knowledge of flow and contaminant transport processes in the vadose zone, and provided recommendations for additional work that should be conducted to address these deficiencies. In the period since (Wood et al., 2000) was prepared, research has been published that, to some degree, address these deficiencies. This document provides a bibliography of reports, journal articles, and conference proceedings published 1999 through mid-2003 that are relevant to the vadose zone at or near the INEEL and provides a brief description of each work. Publications that address specific deficiencies or recommendations are identified, and pertinent information from selected publications is presented.

  5. Coexistence and transition between shear zones in slow granular flows.

    Science.gov (United States)

    Moosavi, Robabeh; Shaebani, M Reza; Maleki, Maniya; Török, János; Wolf, Dietrich E; Losert, Wolfgang

    2013-10-04

    We report experiments on slow granular flows in a split-bottom Couette cell that show novel strain localization features. Nontrivial flow profiles have been observed which are shown to be the consequence of simultaneous formation of shear zones in the bulk and at the boundaries. The fluctuating band model based on a minimization principle can be fitted to the experiments over a large variation of morphology and filling height with one single fit parameter, the relative friction coefficient μ(rel) between wall and bulk. The possibility of multiple shear zone formation is controlled by μ(rel). Moreover, we observe that the symmetry of an initial state, with coexisting shear zones at both side walls, breaks spontaneously below a threshold value of the shear velocity. A dynamical transition between two asymmetric flow states happens over a characteristic time scale which depends on the shear strength.

  6. Imaging groundwater infiltration dynamics in the karst vadose zone with long-term ERT monitoring

    Science.gov (United States)

    Watlet, Arnaud; Kaufmann, Olivier; Triantafyllou, Antoine; Poulain, Amaël; Chambers, Jonathan E.; Meldrum, Philip I.; Wilkinson, Paul B.; Hallet, Vincent; Quinif, Yves; Van Ruymbeke, Michel; Van Camp, Michel

    2018-03-01

    Water infiltration and recharge processes in karst systems are complex and difficult to measure with conventional hydrological methods. In particular, temporarily saturated groundwater reservoirs hosted in the vadose zone can play a buffering role in water infiltration. This results from the pronounced porosity and permeability contrasts created by local karstification processes of carbonate rocks. Analyses of time-lapse 2-D geoelectrical imaging over a period of 3 years at the Rochefort Cave Laboratory (RCL) site in south Belgium highlight variable hydrodynamics in a karst vadose zone. This represents the first long-term and permanently installed electrical resistivity tomography (ERT) monitoring in a karst landscape. The collected data were compared to conventional hydrological measurements (drip discharge monitoring, soil moisture and water conductivity data sets) and a detailed structural analysis of the local geological structures providing a thorough understanding of the groundwater infiltration. Seasonal changes affect all the imaged areas leading to increases in resistivity in spring and summer attributed to enhanced evapotranspiration, whereas winter is characterised by a general decrease in resistivity associated with a groundwater recharge of the vadose zone. Three types of hydrological dynamics, corresponding to areas with distinct lithological and structural features, could be identified via changes in resistivity: (D1) upper conductive layers, associated with clay-rich soil and epikarst, showing the highest variability related to weather conditions; (D2) deeper and more resistive limestone areas, characterised by variable degrees of porosity and clay contents, hence showing more diffuse seasonal variations; and (D3) a conductive fractured zone associated with damped seasonal dynamics, while showing a great variability similar to that of the upper layers in response to rainfall events. This study provides detailed images of the sources of drip

  7. Imaging groundwater infiltration dynamics in the karst vadose zone with long-term ERT monitoring

    Directory of Open Access Journals (Sweden)

    A. Watlet

    2018-03-01

    Full Text Available Water infiltration and recharge processes in karst systems are complex and difficult to measure with conventional hydrological methods. In particular, temporarily saturated groundwater reservoirs hosted in the vadose zone can play a buffering role in water infiltration. This results from the pronounced porosity and permeability contrasts created by local karstification processes of carbonate rocks. Analyses of time-lapse 2-D geoelectrical imaging over a period of 3 years at the Rochefort Cave Laboratory (RCL site in south Belgium highlight variable hydrodynamics in a karst vadose zone. This represents the first long-term and permanently installed electrical resistivity tomography (ERT monitoring in a karst landscape. The collected data were compared to conventional hydrological measurements (drip discharge monitoring, soil moisture and water conductivity data sets and a detailed structural analysis of the local geological structures providing a thorough understanding of the groundwater infiltration. Seasonal changes affect all the imaged areas leading to increases in resistivity in spring and summer attributed to enhanced evapotranspiration, whereas winter is characterised by a general decrease in resistivity associated with a groundwater recharge of the vadose zone. Three types of hydrological dynamics, corresponding to areas with distinct lithological and structural features, could be identified via changes in resistivity: (D1 upper conductive layers, associated with clay-rich soil and epikarst, showing the highest variability related to weather conditions; (D2 deeper and more resistive limestone areas, characterised by variable degrees of porosity and clay contents, hence showing more diffuse seasonal variations; and (D3 a conductive fractured zone associated with damped seasonal dynamics, while showing a great variability similar to that of the upper layers in response to rainfall events. This study provides detailed images of

  8. Climate change impact on groundwater levels in the Guarani Aquifer outcrop zone

    Science.gov (United States)

    Melo, D. D.; Wendland, E.

    2013-12-01

    The unsustainable use of groundwater in many countries might cause water availability restrictions in the future. Such issue is likely to worsen due to predicted climate changes for the incoming decades. As numerous studies suggest, aquifers recharge rates will be affected as a result of climate change. The Guarani Aquifer System (GAS) is one of the most important transboundary aquifer in the world, providing drinkable water for millions of people in four South American countries (Brazil, Argentina, Uruguay and Paraguay). Considering the GAS relevance and how its recharge rates might be altered by climatic conditions anomalies, the objective of this work is to assess possible climate changes impacts on groundwater levels in this aquifer outcrop zone. Global Climate Models' (GCM) outputs were used as inputs in a transient flux groundwater model created using the software SPA (Simulation of Process in Aquifers), enabling groundwater table fluctuation to be evaluated under distinct climatic scenarios. Six monitoring wells, located in a representative basin (Ribeirão da Onça basin) inside a GAS outcrop zone (ROB), provided water table measurements between 2004 and 2011 to calibrate the groundwater model. Using observed climatic data, a water budget method was applied to estimate recharge in different types of land uses. Statistically downscaled future climate scenarios were used as inputs for that same recharge model, which provided data for running SPA under those scenarios. The results show that most of the GCMs used here predict temperature arises over 275,15 K and major monthly rainfall mean changes to take place in the dry season. During wet seasons, those means might experience around 50% decrease. The transient model results indicate that water table variations, derived from around 70% of the climate scenarios, would vary below those measured between 2004 and 2011. Among the thirteen GCMs considered in this work, only four of them predicted more extreme

  9. Numerical groundwater flow calculations at the Finnsjoen study site - The influence of the regional gradient

    International Nuclear Information System (INIS)

    Lindbom, B.; Boghammar, A.

    1992-04-01

    The present report describes the modelling efforts of the groundwater flow situation at the Finnsjoen site in northern Uppland, approximately 140 km north of Stockholm. The study forms part of the SKB 91 performance assessment project, and aims at describing the model sensitivity to changes in the prevailing regional gradient, as well as the local, with regard to both direction and magnitude. Particular emphasis has been put into the evaluation of travel times and travel paths form a potential repository, and also on flux values at repository level. The analyses were based on the finite element technique and made use of the NAMMU-code for stationary calculations in three dimensions. The fracture zones within the modelled area were modelled implicitly with an averaging technique. (au)

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

    Science.gov (United States)

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

    2011-01-01

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

  11. Variable-density ground-water flow and paleohydrology in the Waste Isolation Pilot Plant (WIPP) region, southeastern New Mexico

    International Nuclear Information System (INIS)

    Davies, P.B.

    1989-01-01

    Variable-density groundwater flow was studied near the Waste Isolation Pilot Plant in southeastern New Mexico. An analysis of the relative magnitude of pressure-related and density-related flow-driving forces indicates that density-related gravity effects are not significant at the plant and to the west but are significant in areas to the north, northeast, and south. A regional-scale model of variable-density groundwater flow in the Culebra Dolomite member of the Rustler Formation indicates that the flow velocities are relatively rapid west of the site and extremely slow east and northeast of the site. In the transition zone between those two extremes, which includes the plant, velocities are highly variable. Sensitivity simulations indicates that the central and western parts of the region, including the plant, are fairly well isolated from the eastern and northeastern boundaries. Vertical-flux simulations indicate that as much as 25% of total inflow to the Culebra could be entering as vertical flow, with most of this flow occurring west of the plant. A simple cross-sectional model was developed to examine the flow system as it drains through time following recharge during a past glacial pluvial. This model indicates that the system as a whole drains very slowly and that it apparently could have sustained flow from purely transient drainage following recharge of the system during the Pleistocene

  12. Delineation of groundwater development potential zones in parts of marginal Ganga Alluvial Plain in South Bihar, Eastern India.

    Science.gov (United States)

    Saha, Dipankar; Dhar, Y R; Vittala, S S

    2010-06-01

    A part of the Gangetic Alluvial Plain covering 2,228 km(2), in the state of Bihar, is studied for demarcating groundwater development potential zones. The area is mainly agrarian and experiencing intensive groundwater draft to the tune of 0.12 million cubic metre per square kilometres per year from the Quaternary marginal alluvial deposits, unconformably overlain northerly sloping Precambrian bedrock. Multiparametric data on groundwater comprising water level, hydraulic gradient (pre- and post-monsoon), aquifer thickness, permeability, suitability of groundwater for drinking and irrigation and groundwater resources vs. draft are spatially analysed and integrated on a Geographical Information System platform to generate thematic layers. By integrating these layers, three zones have been delineated based on groundwater development potential. It is inferred that about 48% of the area covering northern part has high development potential, while medium and low development potential category covers 41% of the area. Further increase in groundwater extraction is not recommended for an area of 173 km(2), affected by over-exploitation. The replenishable groundwater resource available for further extraction has been estimated. The development potential enhances towards north with increase in thickness of sediments. Local deviations are due to variation of-(1) cumulative thickness of aquifers, (2) deeper water level resulting from localised heavy groundwater extraction and (3) aquifer permeability.

  13. Mapping of groundwater potential zones in Salem Chalk Hills, Tamil Nadu, India, using remote sensing and GIS techniques.

    Science.gov (United States)

    Thilagavathi, N; Subramani, T; Suresh, M; Karunanidhi, D

    2015-04-01

    This study proposes to introduce the remote sensing and geographic information system (GIS) techniques in mapping the groundwater potential zones. Remote sensing and GIS techniques have been used to map the groundwater potential zones in Salem Chalk Hills, Tamil Nadu, India. Charnockites and fissile hornblende biotite gneiss are the major rock types in this region. Dunites and peridodites are the ultramafic rocks which cut across the foliation planes of the gneisses and are highly weathered. It comprises magnesite and chromite deposits which are excavated by five mining companies by adopting bench mining. The thickness of weathered and fracture zone varies from 2.2 to 50 m in gneissic formation and 5.8 to 55 m in charnockite. At the contacts of gneiss and charnockite, the thickness ranges from 9.0 to 90.8 m favoring good groundwater potential. The mine lease area is underlined by fractured and sheared hornblende biotite gneiss where groundwater potential is good. Water catchment tanks in this area of 5 km radius are small to moderate in size and are only seasonal. They remain dry during summer seasons. As perennial water resources are remote, the domestic and agricultural activities in this region depend mainly upon the groundwater resources. The mines are located in gently slope area, and accumulation of water is not observed except in mine pits even during the monsoon period. Therefore, it is essential to map the groundwater potential zones for proper management of the aquifer system. Satellite imageries were also used to extract lineaments, hydrogeomorphic landforms, drainage patterns, and land use, which are the major controlling factors for the occurrence of groundwater. Various thematic layers pertaining to groundwater existence such as geology, geomorphology, land use/land cover, lineament, lineament density, drainage, drainage density, slope, and soil were generated using GIS tools. By integrating all the above thematic layers based on the ranks and

  14. Vertical Hydraulic Conductivity of Unsaturated Zone by Infiltrometer Analysis of Shallow Groundwater Regime (KUISG

    Directory of Open Access Journals (Sweden)

    Arkan Radhi Ali

    2018-02-01

    Full Text Available A hydrogeologic model was developed and carried out in Taleaa district of 67km2 . The study adopted a determination of KUISG depends upon the double rings infiltrometer model. The tests were carried out in a part of Mesopotamian  Zone which is covered with quaternary deposits  . In general the groundwater levels are about one meter below ground surface.  Theoretically, the inclination angle of the saturated water phase plays an important role in the determination of KUISG. The experimental results prove that the angle of inclination of the saturated phase is identical to the angle of internal friction of the soil. This conclusion is supported by the comparison of the results that obtained from falling head test and infiltrometer measurements for estimating the hydraulic conductivitiy values for ten locations within the study area. The determination of vertical hydraulic conductivity by current infiltrometer model is constrained to only the shallow groundwater regime.7

  15. Assessing the impact of dairy waste lagoons on groundwater quality using a spatial analysis of vadose zone and groundwater information in a coastal phreatic aquifer.

    Science.gov (United States)

    Baram, S; Kurtzman, D; Ronen, Z; Peeters, A; Dahan, O

    2014-01-01

    Dairy waste lagoons are considered to be point sources of groundwater contamination by chloride (Cl(-)), different nitrogen-species and pathogens/microorganisms. The objective of this work is to introduce a methodology to assess the past and future impacts of such lagoons on regional groundwater quality. The method is based on a spatial statistical analysis of Cl(-) and total nitrogen (TN) concentration distributions in the saturated and the vadose (unsaturated) zones. The method provides quantitative data on the relation between the locations of dairy lagoons and the spatial variability in Cl(-) and TN concentrations in groundwater. The method was applied to the Beer-Tuvia region, Israel, where intensive dairy farming has been practiced for over 50 years above the local phreatic aquifer. Mass balance calculations accounted for the various groundwater recharge and abstraction sources and sinks in the entire region. The mass balances showed that despite the small surface area covered by the dairy lagoons in this region (0.8%), leachates from lagoons have contributed 6.0% and 12.6% of the total mass of Cl(-) and TN (mainly as NO3(-)-N) added to the aquifer. The chemical composition of the aquifer and vadose zone water suggested that irrigated agricultural activity in the region is the main contributor of Cl(-) and TN to the groundwater. A low spatial correlation between the Cl(-) and NO3(-)-N concentrations in the groundwater and the on-land location of the dairy farms strengthened this assumption, despite the dairy waste lagoon being a point source for groundwater contamination by Cl(-) and NO3(-)-N. Mass balance calculations, for the vadose zone of the entire region, indicated that drying of the lagoons would decrease the regional groundwater salinization process (11% of the total Cl(-) load is stored under lagoons). A more considerable reduction in the groundwater contamination by NO3(-)-N is expected (25% of the NO3(-)-N load is stored under lagoons). Results

  16. Vadose zone flow convergence test suite

    Energy Technology Data Exchange (ETDEWEB)

    Butcher, B. T. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2017-06-05

    Performance Assessment (PA) simulations for engineered disposal systems at the Savannah River Site involve highly contrasting materials and moisture conditions at and near saturation. These conditions cause severe convergence difficulties that typically result in unacceptable convergence or long simulation times or excessive analyst effort. Adequate convergence is usually achieved in a trial-anderror manner by applying under-relaxation to the Saturation or Pressure variable, in a series of everdecreasing RELAxation values. SRNL would like a more efficient scheme implemented inside PORFLOW to achieve flow convergence in a more reliable and efficient manner. To this end, a suite of test problems that illustrate these convergence problems is provided to facilitate diagnosis and development of an improved convergence strategy. The attached files are being transmitted to you describing the test problem and proposed resolution.

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

    International Nuclear Information System (INIS)

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

    1993-01-01

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

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

    International Nuclear Information System (INIS)

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

    2004-09-01

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

  19. Gravity-driven groundwater flow and slope failure potential: 1. Elastic effective-stress model

    Science.gov (United States)

    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.

  20. Groundwater Flow Model of Göksu Delta Coastal Aquifer System

    Science.gov (United States)

    Erdem Dokuz, Uǧur; Çelik, Mehmet; Arslan, Şebnem; Engin, Hilal

    2016-04-01

    Like many other coastal areas, Göksu Delta (Mersin-Silifke, Southern Turkey) is a preferred place for human settlement especially due to its productive farmlands and water resources. The water dependent ecosystem in Göksu delta hosts about 332 different plant species and 328 different bird species besides serving for human use. Göksu Delta has been declared as Special Environmental Protection Zone, Wildlife Protection Area, and RAMSAR Convention for Wetlands of International Importance area. Unfortunately, rising population, agricultural and industrial activities cause degradation of water resources both by means of quality and quantity. This problem also exists for other wetlands around the world. It is necessary to prepare water management plans by taking global warming issues into account to protect water resources for next generations. To achieve this, the most efficient tool is to come up with groundwater management strategies by constructing groundwater flow models. By this aim, groundwater modeling studies were carried out for Göksu Delta coastal aquifer system. As a first and most important step in all groundwater modeling studies, geological and hydrogeological settings of the study area have been investigated. Göksu Delta, like many other deltaic environments, has a complex structure because it was formed with the sediments transported by Göksu River throughout the Quaternary period and shaped throughout the transgression-regression periods. Both due to this complex structure and the lack of observation wells penetrating deep enough to give an idea of the total thickness of the delta, it was impossible to reveal out the hydrogeological setting in a correct manner. Therefore, six wells were drilled to construct the conceptual hydrogeological model of Göksu Delta coastal aquifer system. On the basis of drilling studies and slug tests that were conducted along Göksu Delta, hydrostratigraphic units of the delta system have been obtained. According to

  1. Effect of irrigation return flow on groundwater recharge in an overexploited aquifer in Bangladesh

    Science.gov (United States)

    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

  2. Integrating geospatial and ground geophysical information as guidelines for groundwater potential zones in hard rock terrains of south India.

    Science.gov (United States)

    Rashid, Mehnaz; Lone, Mahjoor Ahmad; Ahmed, Shakeel

    2012-08-01

    The increasing demand of water has brought tremendous pressure on groundwater resources in the regions were groundwater is prime source of water. The objective of this study was to explore groundwater potential zones in Maheshwaram watershed of Andhra Pradesh, India with semi-arid climatic condition and hard rock granitic terrain. GIS-based modelling was used to integrate remote sensing and geophysical data to delineate groundwater potential zones. In the present study, Indian Remote Sensing RESOURCESAT-1, Linear Imaging Self-Scanner (LISS-4) digital data, ASTER digital elevation model and vertical electrical sounding data along with other data sets were analysed to generate various thematic maps, viz., geomorphology, land use/land cover, geology, lineament density, soil, drainage density, slope, aquifer resistivity and aquifer thickness. Based on this integrated approach, the groundwater availability in the watershed was classified into four categories, viz. very good, good, moderate and poor. The results reveal that the modelling assessment method proposed in this study is an effective tool for deciphering groundwater potential zones for proper planning and management of groundwater resources in diverse hydrogeological terrains.

  3. To Examine effect of Flow Zone Generation Techniques for Numerical Flow Analysis in Hydraulic Turbine

    International Nuclear Information System (INIS)

    Hussain, M.; Khan, J.A.

    2004-01-01

    A numerical study of flow in distributor of Francis Turbine is carried out by using two different techniques of flow zone generation. Distributor of GAMM Francis Turbine is used for present calculation. In present work, flow is assumed to be periodic around the distributor in steady state conditions, therefore computational domain consists of only one blade channel (one stay vane and one guide vane). The distributor computational domain is bounded up stream by cylindrical and downstream by conical patches. The first one corresponds to the spiral casing outflow section, while the second one is considered to be the distributor outlet or runner inlet. Upper and lower surfaces are generated by the revolution of hub and shroud edges. Single connected and multiple connected techniques are considered to generate distributor flow zone for numerical flow analysis of GAMM Francis turbine. The tetrahedral meshes are generated in both the flow zones. Same boundary conditions are applied for both the equivalent flow zones. The three dimensional, laminar flow analysis for both the distributor flow zones of the GAMM Francis turbine operating at the best efficiency point is performed. Gambit and G- Turbo are used as a preprocessor while calculations are done by using Fluent. Finally, numerical results obtained on the distributor outlet are compared with the available experimental data to validate the two different methodologies and examine their accuracy. (author)

  4. Modelling of groundwater flow and flow paths for a large regional domain in northeast Uppland. A three-dimensional, mathematical modelling of groundwater flows and flow paths on a super-regional scale, for different complexity levels of the flow domain

    International Nuclear Information System (INIS)

    Holmen, Johan G.; Stigsson, Martin; Marsic, Niko; Gylling, Bjoern

    2003-12-01

    The general purpose of this study is to estimate the groundwater flow for a large regional domain by use of groundwater models; and to do that with such a resolution (degree of detail) that important local properties of the flow system studied is represented in the established models. Based on the results of the groundwater modelling, we have compared different theoretical locations of a repository for nuclear waste, considering length and breakthrough time (advective flow) for flow paths from such a repository. The area studied is located in Sweden, in the Northeast of the Uppland province. The area has a maximum horizontal extension of 90 km by 50 km, and the size of the area is approximately 2,000 km 2 . The study is based on a system analysis approach. The studied system is the groundwater flow in the rock mass of Northeast Uppland. To reach the objectives of the study, different mathematical models were devised of the studied domain; these models will, in an idealised and simplified way, reproduce the groundwater movements at the area studied. The formal models (the mathematical models) used for simulation of the groundwater flow are three dimensional mathematical descriptions of the studied hydraulic system. For establishment of the formal models we used two different numerical codes GEOAN, which is based on the finite difference method and NAMMU, which is based on the finite element method. Considering flow path lengths and breakthrough times from a theoretical repository, we have evaluated the following: Importance of the local and regional topography; Importance of cell size in the numerical model; Importance of depth of domain represented in the numerical model; Importance of regional fracture zones; Importance of local lakes; Importance of areas covered by a clay layer; Importance of a modified topography; Importance of the shore level progress. Importance of density dependent flow. The results of the study includes: Length and breakthrough time of flow

  5. Modelling of groundwater flow and flow paths for a large regional domain in northeast Uppland. A three-dimensional, mathematical modelling of groundwater flows and flow paths on a super-regional scale, for different complexity levels of the flow domain

    Energy Technology Data Exchange (ETDEWEB)

    Holmen, Johan G.; Stigsson, Martin [Golder Associates, Stockholm (Sweden); Marsic, Niko; Gylling, Bjoern [Kemakta Konsult AB, Stockholm (Sweden)

    2003-12-01

    The general purpose of this study is to estimate the groundwater flow for a large regional domain by use of groundwater models; and to do that with such a resolution (degree of detail) that important local properties of the flow system studied is represented in the established models. Based on the results of the groundwater modelling, we have compared different theoretical locations of a repository for nuclear waste, considering length and breakthrough time (advective flow) for flow paths from such a repository. The area studied is located in Sweden, in the Northeast of the Uppland province. The area has a maximum horizontal extension of 90 km by 50 km, and the size of the area is approximately 2,000 km{sup 2}. The study is based on a system analysis approach. The studied system is the groundwater flow in the rock mass of Northeast Uppland. To reach the objectives of the study, different mathematical models were devised of the studied domain; these models will, in an idealised and simplified way, reproduce the groundwater movements at the area studied. The formal models (the mathematical models) used for simulation of the groundwater flow are three dimensional mathematical descriptions of the studied hydraulic system. For establishment of the formal models we used two different numerical codes GEOAN, which is based on the finite difference method and NAMMU, which is based on the finite element method. Considering flow path lengths and breakthrough times from a theoretical repository, we have evaluated the following: Importance of the local and regional topography; Importance of cell size in the numerical model; Importance of depth of domain represented in the numerical model; Importance of regional fracture zones; Importance of local lakes; Importance of areas covered by a clay layer; Importance of a modified topography; Importance of the shore level progress. Importance of density dependent flow. The results of the study includes: Length and breakthrough time of

  6. Numerical study on the effects of the alternative structure geometries on the groundwater flow at the Romuvaara site

    International Nuclear Information System (INIS)

    Koskinen, L.; Meling, K.

    1994-11-01

    The work has two aims. Firstly, it completes the numerical modelling work for the groundwater flow at the Romuvaara site in Finland performed during the preliminary site investigations by varying geometries of the most significant fracture zones. The modified fracture zone geometries are selected within the uncertainties of the structure of the bedrock model. Secondly, the work studies the effects of several potential fracture zones. The locations and geometries of these zones are decided in such a way that either they offer potential or alternative hydrogeologic connections that would explain the anomalies in the results of the earlier field investigations or their existence has been implied by geophysical studies. The field results comprise the measured hydraulic head values under the natural conditions in boreholes KR1 -KRS, and the hydraulic head responses in the pumping test. The work employs the calibrated flow model developed in the preliminary site investigations as the base case, that is modified to correspond to the alternative geometries. Before the simulations with the alternative geometries, the boundary condition for the top of the flow model is partly changed in this work in order to revoke the modification motivated by incorrect field data that were used in the calibration of the flow model. (25 refs., 27 figs., 1 tab.)

  7. Development of honeycomb type orifices for flow zoning in PFBR

    Energy Technology Data Exchange (ETDEWEB)

    Pandey, G.K., E-mail: gkpandey@igcar.gov.in; Ramdasu, D.; Padmakumar, G.; Prakash, V.; Rajan, K.K.

    2013-09-15

    Highlights: • Cavitation free flow zoning devices are developed for reactor core in PFBR. • These devices are experimentally investigated for their hydraulic characteristics. • Pressure drop and cavitation are two main characteristics to be investigated. • Various configurations of devices utilized in different zones are discussed. • Loss coefficient for each configuration is compared and reported. -- Abstract: The prototype fast breeder reactor (PFBR) is in its advanced phase of construction at Kalpakkam, India. It is a sodium cooled, pool type reactor with two loop concept where each loop have one primary sodium pump (PSP), one secondary sodium pump (SSP) and two intermediate heat exchangers (IHX). PFBR core subassemblies (SA) are supported vertically inside the sleeves provided in the grid plate (GP). The GP acts as a coolant header through which flow is distributed among the SA to remove fission heat. Since the power profile of the reactor core is not uniform, it is necessary to distribute the coolant flow (called flow zoning) to each subassembly according to their power levels to get maximum mean outlet temperature of sodium at core outlet. To achieve this, PFBR core is divided into 15 zones such as fuel, blanket, reflector, storage, etc. according to their respective power levels. The flow zoning in the different SAs of the reactor core is achieved by installing permanent pressure dropping devices in the foot of the subassembly. Orifices having honey-comb type geometry were developed to meet the flow zoning requirements of fuel zone. These orifices being of very complex geometry requires precision methods of manufacturing to achieve the desired shape under specified tolerances. Investment casting method was optimized to manufacture this orifice plate successfully. Hydraulics of these orifices is important in achieving the required pressure drop without cavitation. The pressure drop across these orifice geometries depends mainly on geometrical

  8. Groundwater flow modeling in construction phase of the Mizunami Underground Research Laboratory project

    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)

  9. Groundwater flow system under a rapidly urbanizing coastal city as determined by hydrogeochemistry

    Science.gov (United States)

    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.

  10. Evaluation of geohydrologic framework, recharge estimates and ground-water flow of the Joshua Tree area, San Bernardino County, California

    Science.gov (United States)

    Nishikawa, Tracy; Izbicki, John A.; Hevesi, Joseph A.; Stamos, Christina L.; Martin, Peter

    2005-01-01

    Ground water historically has been the sole source of water supply for the community of Joshua Tree in the Joshua Tree ground-water subbasin of the Morongo ground-water basin in the southern Mojave Desert. The Joshua Basin Water District (JBWD) supplies water to the community from the underlying Joshua Tree ground-water subbasin. The JBWD is concerned with the long-term sustainability of the underlying aquifer. To help meet future demands, the JBWD plans to construct production wells in the adjacent Copper Mountain ground-water subbasin. As growth continues in the desert, there may be a need to import water to supplement the available ground-water resources. In order to manage the ground-water resources and to identify future mitigating measures, a thorough understanding of the ground-water system is needed. The purpose of this study was threefold: (1) improve the understanding of the geohydrologic framework of the Joshua Tree and Copper Mountain ground-water subbasins, (2) determine the distribution and quantity of recharge using field and numerical techniques, and (3) develop a ground-water flow model that can be used to help manage the water resources of the region. The geohydrologic framework was refined by collecting and interpreting water-level and water-quality data, geologic and electric logs, and gravity data. The water-bearing deposits in the Joshua Tree and Copper Mountain ground-water subbasins are Quarternary alluvial deposits and Tertiary sedimentary and volcanic deposits. The Quarternary alluvial deposits were divided into two aquifers (referred to as the 'upper' and the 'middle' alluvial aquifers), which are about 600 feet (ft) thick, and the Tertiary sedimentary and volcanic deposits were assigned to a single aquifer (referred to as the 'lower' aquifer), which is as thick as 1,500 ft. The ground-water quality of the Joshua Tree and Copper Mountain ground-water subbasins was defined by collecting 53 ground-water samples from 15 wells (10 in the

  11. Isotope hydrology of groundwaters in the Donana National Park and the associated zone of influence

    International Nuclear Information System (INIS)

    Plata, A.; Baonza, E.; Silgado, A.

    1984-01-01

    The authors describe a study, using environmental isotopes, of the groundwaters of a complex hydrological system formed by a free recharge zone with a multi-layer structure, a confined zone with connate waters trapped by the deposition of a thick clay layer in a coastal pool environment, and a series of both recent and ancient highly permeable dune formations. Attempts have been made, using tritium of thermonuclear origin, to determine the approximate average recharge rate during the last 28 years in the free aquifer zone. Despite the difficulties encountered, the value of 78 mm/a obtained, which is 13.2% of the average precipitation, is very similar to that obtained using conventional methods (approximately 84 mm/a). As was expected, there was no tritium in the confined zone. Carbon-14 was used to determine the reduced velocity of the underground stream and to confirm the network of streams deduced from conductivity measurements. The age-correction methods proposed by Tamers, Pearson, Mook and Fontes were compared. The differences in age between the last method and the first two are reasonable and can be explained by the isotopic interchange between the CaCO 3 of the rock formation and the gaseous CO 2 included in Fontes' model. On the other hand, the differences found with the Mook method are considerable, particularly for sample values below delta 13 C. The last model is more sensitive to changes in delta 13 C, and the interval of this parameter for which this model gives reasonable values of age is very small. In addition, the 14 C made it possible to determine the sedimentation velocity of clays in the swamp zone. The stable isotopes in the water confirmed the hypothesis that the underground waters in the confinement zone are a mixture of fresh water which has infiltrated into the recharge zone and of connate water trapped by the deposition of the clay layer. (author)

  12. Heterogeneity of groundwater storage properties in the critical zone of Irish metamorphic basement from geophysical surveys and petrographic analyses

    Science.gov (United States)

    Comte, Jean-Christophe; Cassidy, Rachel; Caulfield, John; Nitsche, Janka; Ofterdinger, Ulrich; Wilson, Christopher

    2016-04-01

    Weathered/fractured bedrock aquifers contain groundwater resources that are crucial in hard rock basement regions for rural water supply and maintaining river flow and ecosystem resilience. Groundwater storage in metamorphic rocks is subject to high spatial variations due to the large degree of heterogeneity in fracture occurrence and weathering patterns. Point measurements such as borehole testing are, in most cases, insufficient to characterise and quantify those storage variations because borehole sampling density is usually much lower than the scale of heterogeneities. A suite of geophysical and petrographic investigations was implemented in the weathered/fractured micaschist basement of Donegal, NW Ireland. Electrical Resistivity Tomography provided a high resolution 2D distribution of subsurface resistivities. Resistivity variations were transferred into storage properties (i.e. porosities) in the saturated critical zone of the aquifer through application of a petrophysical model derived from Archie's Law. The petrophysical model was calibrated using complementary borehole gamma logging and clay petrographic analysis at multi-depth well clusters distributed along a hillslope transect at the site. The resulting distribution of porosities shows large spatial variations along the studied transect. With depth, porosities rapidly decrease from about a few % in the uppermost, highly weathered basement to less than 0.5% in the deep unweathered basement, which is encountered at depths of between 10 and 50m below the ground surface. Along the hillslope, porosities decrease with distance from the river in the valley floor, ranging between 5% at the river to less than 1% at the top of the hill. Local traces of regional fault zones that intersect the transect are responsible for local increases in porosity in relation to deeper fracturing and weathering. Such degrees of spatial variation in porosity are expected to have a major impact on the modality of the response of

  13. 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)

  14. Groundwater flow and hydrogeochemical evolution in the Jianghan Plain, central China

    Science.gov (United States)

    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.

  15. Combined geophysical techniques for detailed groundwater flow investigation in tectonically deformed fractured rocks

    Directory of Open Access Journals (Sweden)

    John Alexopoulos

    2014-02-01

    Full Text Available In this paper we present a combination of several near surface geophysical investigation techniques with high resolution remote sensing image interpretations, in order to define the groundwater flow paths and whether they can be affected by future seismic events. A seasonal spring (Amvrakia located at the foot of Meteora pillars near the village of Kastraki (Greece was chosen as a test site. The Meteora conglomeratic formations crop out throughout the study area and are characterized by large discontinuities caused by post Miocene till present tectonic deformation [Ferriere et al. 2011, Royden and Papanikolaou 2011]. A network of groundwater pathways has been developed above the impermeable marls underlying the conglomeratic strata. Our research aims to define these water pathways in order to investigate and understand the exact mechanism of the spring by mapping the exposed discontinuity network with classic field mapping and remote sensing image interpretation and define their underground continuity with the contribution of near surface geophysical techniques. Five Very Low Frequency (VLF profiles were conducted with different directions around the spring aiming to detect possible conductive zones in the conglomeratic formations that the study area consists of. Moreover, two Electrical Resistivity Tomography (ERT sections of a total length of 140m were carried out parallel to the VLF profiles for cross-checking and verifying the geophysical information. Both techniques revealed important conductive zones (<200 Ohm m within the conglomerate strata, which we interpret as discontinuities filled with water supplying the spring, which are quite vulnerable to displacements as the hydraulic connections between them might be easily disturbed after a future seismic event.

  16. Stable isotope and groundwater flow dynamics of agricultural irrigation recharge into groundwater resources of the Central Valley, California

    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

  17. 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.

  18. 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

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

    OpenAIRE

    Brown, Brendan

    2005-01-01

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

  20. Seasonal Arsenic Accumulation in Stream Sediments at a Groundwater Discharge Zone

    DEFF Research Database (Denmark)

    MacKay, Allison A.; Gan, Ping; Yu, Ran

    2014-01-01

    Seasonal changes in arsenic and iron accumulation rates were examined in the sediments of a brook that receives groundwater discharges of arsenic and reduced iron. Clean glass bead columns were deployed in sediments for known periods over the annual hydrologic cycle to monitor changes in arsenic...... and iron concentrations in bead coatings. The highest accumulation rates occurred during the dry summer period (July-October) when groundwater discharges were likely greatest at the sample locations. The intermediate flow period (October-March), With higher surface water: levels, was associated with losses...... of arsenic and iron from bead column coatings at. depths below 2-6 cm. Batch incubations indicated iron releases from solids to be induced by biological reduction of iron (oxy)hydroxide solids. Congruent arsenic releases during incubation were limited by the high arsenic sorption capacity (0.536 mg...

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

    Science.gov (United States)

    Leighton, David A.; Phillips, Steven P.

    2003-01-01

    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

  2. Controls on groundwater flow in the Bengal Basin of India and Bangladesh: regional modeling analysis

    Science.gov (United States)

    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.

  3. 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.

  4. Controls on groundwater flow in the Bengal Basin of India and Bangladesh: Regional modeling analysis

    Science.gov (United States)

    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.

  5. 3D Groundwater flow model at the Upper Rhine Graben scale to delineate preferential target areas for geothermal projects

    Science.gov (United States)

    Armandine Les Landes, Antoine; Guillon, Théophile; Peter-Borie, Mariane; Rachez, Xavier

    2017-04-01

    Any deep unconventional geothermal project remains risky because of the uncertainty regarding the presence of the geothermal resource at depth and the drilling costs increasing accordingly. That's why this resource must be located as precisely as possible to increase the chances of successful projects and their economic viability. To minimize the risk, as much information as possible should be gathered prior to any drilling. Usually, the position of the exploration wells of geothermal energy systems is chosen based on structural geology observations, geophysics measurements and geochemical analyses. Confronting these observations to results from additional disciplines should bring more objectivity in locating the region to explore and where to implant the geothermal system. The Upper Rhine Graben (URG) is a tectonically active rift system that corresponds to one branch of the European Cenozoic Rift System where the basin hosts a significant potential for geothermal energy. The large fault network inherited from a complex tectonic history and settled under the sedimentary deposits hosts fluid circulation patterns. Geothermal anomalies are strongly influenced by fluid circulations within permeable structures such as fault zones. In order to better predict the location of the geothermal resource, it is necessary to understand how it is influenced by heat transport mechanisms such as groundwater flow. The understanding of fluid circulation in hot fractured media at large scale can help in the identification of preferential zones at a finer scale where additional exploration can be carried out. Numerical simulations is a useful tool to deal with the issue of fluid circulations through large fault networks that enable the uplift of deep and hot fluids. Therefore, we build a numerical model to study groundwater flow at the URG scale (150 x 130km), which aims to delineate preferential zones. The numerical model is based on a hybrid method using a Discrete Fracture Network

  6. 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...

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

    Science.gov (United States)

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

    2014-01-01

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

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

    Science.gov (United States)

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

    2004-01-01

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

  9. 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 ...

  10. 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

  11. 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

  12. Site-scale groundwater flow modelling of Aberg and upscaling of conductivity

    International Nuclear Information System (INIS)

    Walker, Douglas; Gylling, Bjoern

    2002-04-01

    A recent performance assessment study of spent nuclear fuel disposal in Sweden, Safety Report 1997 (SR 97) included modelling of flow and transport in fractured host rocks. Hydraulic conductivity measurements in this system exhibit a strong scale dependence that needed to be addressed when determining the mean and variogram of the hydraulic conductivity for finite-difference blocks and when nesting site-scale models within regional scale models. This study applies four upscaling approaches to the groundwater flow models of Aberg, one of the hypothetical SR 97 repositories. The approaches are: 1) as in SR 97, empirically upscaling the mean conductivity via the observed scale dependence of measurements, and adjusting the covariance via numerical regularisation; 2) empirically upscaling as in SR 97, but considering fracture zones as two-dimensional features; 3) adapting the effective conductivity of stochastic continuum mechanics to upscale the mean, and geostatistical regularisation for variogram; and 4) the analytical approach of Indelman and Dagan. These four approaches are evaluated for their effects on simple measures of repository performance including the canister flux, the advective travel time from representative canister locations to the ground surface, and the F-quotient. A set of sensitivity analyses suggest that the results of the SR 97 Aberg Base Case are insensitive to minor computational changes and to the changes in the properties of minor fracture zones. The comparison of alternative approaches to upscaling indicates that, for the methods examined in this study, the greatest consistency of boundary flows between the regional and site-scale models was achieved when using the scale dependence of hydraulic conductivity observed at Aespoe for the rock domains, the hydraulic conductivities of the large-scale interference tests for the conductor domain, and a numerical regularisation based on Moye's formula for the variogram. The assumption that the

  13. Carbon mineralization and pyrite oxidation in groundwater: Importance for silicate weathering in boreal forest soils and stream base-flow chemistry

    International Nuclear Information System (INIS)

    Klaminder, J.; Grip, H.; Moerth, C.-M.; Laudon, H.

    2011-01-01

    Research highlights: → Organic compounds is mineralized during later transport in deep groundwater aquifers. → Carbonic acid generated by this process stimulates dissolution of silicate minerals. → Protons derived from pyrite oxidation also affects weathering in deep groundwater. → The identified weathering mechanisms affect base-flow chemistry in boreal streams. - Abstract: What role does mineralized organic C and sulfide oxidation play in weathering of silicate minerals in deep groundwater aquifers? In this study, how H 2 CO 3 , produced as a result of mineralization of organic matter during groundwater transport, affects silicate weathering in the saturated zone of the mineral soil along a 70 m-long boreal hillslope is demonstrated. Stream water measurements of base cations and δ 18 O are included to determine the importance of the deep groundwater system for downstream surface water. The results suggest that H 2 CO 3 generated from organic compounds being mineralized during the lateral transport stimulates weathering at depths between 0.5 and 3 m in the soil. This finding is indicated by progressively increasing concentrations of base cations-, silica- and inorganic C (IC) in the groundwater along the hillslope that co-occur with decreasing organic C (OC) concentrations. Protons derived from sulfide oxidation appear to be an additional driver of the weathering process as indicated by a build-up of SO 4 2- in the groundwater during lateral transport and a δ 34 S per mille value of +0.26-3.76 per mille in the deep groundwater indicating S inputs from pyrite. The two identified active acids in the deep groundwater are likely to control the base-flow chemistry of streams draining larger catchments (>1 km 2 ) as evident by δ 18 O signatures and base cation concentrations that overlap with that of the groundwater.

  14. Carbon mineralization and pyrite oxidation in groundwater: Importance for silicate weathering in boreal forest soils and stream base-flow chemistry

    Energy Technology Data Exchange (ETDEWEB)

    Klaminder, J., E-mail: jonatan.klaminder@emg.umu.se [Department of Forest Ecology and Management, SLU, SE-901 83 Umea (Sweden)] [Department of Ecology and Environmental Science, Umea University, SE-901 87 (Sweden); Grip, H. [Department of Forest Ecology and Management, SLU, SE-901 83 Umea (Sweden); Moerth, C.-M. [Department of Geological Sciences, Stockholm University, 106 91 Stockholm (Sweden); Laudon, H. [Department of Forest Ecology and Management, SLU, SE-901 83 Umea (Sweden)

    2011-03-15

    Research highlights: {yields} Organic compounds is mineralized during later transport in deep groundwater aquifers. {yields} Carbonic acid generated by this process stimulates dissolution of silicate minerals. {yields} Protons derived from pyrite oxidation also affects weathering in deep groundwater. {yields} The identified weathering mechanisms affect base-flow chemistry in boreal streams. - Abstract: What role does mineralized organic C and sulfide oxidation play in weathering of silicate minerals in deep groundwater aquifers? In this study, how H{sub 2}CO{sub 3}, produced as a result of mineralization of organic matter during groundwater transport, affects silicate weathering in the saturated zone of the mineral soil along a 70 m-long boreal hillslope is demonstrated. Stream water measurements of base cations and {delta}{sup 18}O are included to determine the importance of the deep groundwater system for downstream surface water. The results suggest that H{sub 2}CO{sub 3} generated from organic compounds being mineralized during the lateral transport stimulates weathering at depths between 0.5 and 3 m in the soil. This finding is indicated by progressively increasing concentrations of base cations-, silica- and inorganic C (IC) in the groundwater along the hillslope that co-occur with decreasing organic C (OC) concentrations. Protons derived from sulfide oxidation appear to be an additional driver of the weathering process as indicated by a build-up of SO{sub 4}{sup 2-} in the groundwater during lateral transport and a {delta}{sup 34}S per mille value of +0.26-3.76 per mille in the deep groundwater indicating S inputs from pyrite. The two identified active acids in the deep groundwater are likely to control the base-flow chemistry of streams draining larger catchments (>1 km{sup 2}) as evident by {delta}{sup 18}O signatures and base cation concentrations that overlap with that of the groundwater.

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

    Science.gov (United States)

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

    2016-02-01

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

  16. Application of remote sensing, GIS and MCA techniques for delineating groundwater prospect zones in Kashipur block, Purulia district, West Bengal

    Science.gov (United States)

    Nag, S. K.; Kundu, Anindita

    2018-03-01

    Demand of groundwater resources has increased manifold with population expansion as well as with the advent of modern civilization. Assessment, planning and management of groundwater resource are becoming crucial and extremely urgent in recent time. The study area belongs to Kashipur block, Purulia district, West Bengal. The area is characterized with dry climate and hard rock terrain. The objective of this study is to delineate groundwater potential zone for the assessment of groundwater availability using remote sensing, GIS and MCA techniques. Different thematic layers such as hydrogeomorphology, slope and lineament density maps have been transformed to raster data in TNT mips pro2012. To assign weights and ranks to different input factor maps, multi-influencing factor (MIF) technique has been used. The weights assigned to each factor have been computed statistically. Weighted index overlay modeling technique was used to develop a groundwater potential zone map with three weighted and scored parameters. Finally, the study area has been categorized into four distinct groundwater potential zones—excellent 1.5% (6.45 sq. km), good 53% (227.9 sq. km), moderate 45% (193.5 sq. km.) and poor 0.5% (2.15 sq. km). The outcome of the present study will help local authorities, researchers, decision makers and planners in formulating proper planning and management of groundwater resources in different hydrogeological situations.

  17. Groundwater flows in Meuse/Haute-Marne aquifer system and the importance of the evolution of the geomorphology over the next million of years

    International Nuclear Information System (INIS)

    Holmen, J.; Benabderrahmane, H.; Brulhet, J.

    2012-01-01

    Document available in extended abstract form only. A clay-stone formation of Callovo-Oxfordian age is found throughout the multilayered sedimentary fill of the Paris Basin. It is considered as a potential host rock for France's high and intermediate-level long-lived radioactive waste. The Callovo-Oxfordian layer is located between an overlying limestone of Oxfordian age and an underlying limestone of Dogger age.. The Meuse/Haute-Marne sector area is located in the East of France, the area includes the Bure investigation site and a domain referred to as the 'transposition zone' selected as a suitable location for France's high- and intermediate-level long-lived radioactive waste The objective of the study was to estimate how the groundwater flow in the Meuse/Haute- Marne aquifer system will change because of the geomorphologic evolution over the next 1 million of years. The future groundwater flows and the future evolution of the vertical hydraulic gradient in the transposition zone are of importance in the performance assessment and the safety analysis of a future repository for radioactive waste. The study is based on numerical modelling and the established model covers the whole of the Paris basin. The studied time period corresponds to 1 million years into the future. The initial geometry of geological layers as well as the conductivity and the porosity of the layers are input data to model, and defined by the single-continuum multi-scale hydrogeological model of the Paris Basin and the Meuse/Haute-Marne Sector area as developed by Andra. A description of the transient geomorphologic evolution was used as input data to the groundwater flow modelling. The description include: (i) The deformation of the geological layers as a result of a non-symmetric tectonic uplift of the Paris basin and (ii) The movement of the topography because of mechanical erosion along valleys, chemical erosion along plateaus and sedimentation along valleys. The modelling of the

  18. Effects of Sea Level Rise on Groundwater Flow Paths in a Coastal Aquifer System

    Science.gov (United States)

    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.

  19. A conceptual model of the hydrogeologic framework, geochemistry, and groundwater-flow system of the Edwards-Trinity and related aquifers in the Pecos County region, Texas

    Science.gov (United States)

    Bumgarner, Johnathan R.; Stanton, Gregory P.; Teeple, Andrew; Thomas, Jonathan V.; Houston, Natalie A.; Payne, Jason; Musgrove, MaryLynn

    2012-01-01

    A conceptual model of the hydrogeologic framework, geochemistry, and groundwater-flow system of the Edwards-Trinity and related aquifers, which include the Pecos Valley, Igneous, Dockum, Rustler, and Capitan Reef aquifers, was developed as the second phase of a groundwater availability study in the Pecos County region in west Texas. The first phase of the study was to collect and compile groundwater, surface-water, water-quality, geophysical, and geologic data in the area. The third phase of the study involves a numerical groundwater-flow model of the Edwards-Trinity aquifer in order to simulate groundwater conditions based on various groundwater-withdrawal scenarios. Resource managers plan to use the results of the study to establish management strategies for the groundwater system. The hydrogeologic framework is composed of the hydrostratigraphy, structural features, and hydraulic properties of the groundwater system. Well and geophysical logs were interpreted to define the top and base surfaces of the Edwards-Trinity aquifer units. Elevations of the top and base of the Edwards-Trinity aquifer generally decrease from the southwestern part of the study area to the northeast. The thicknesses of the Edwards-Trinity aquifer units were calculated using the interpolated top and base surfaces of the hydrostratigraphic units. Some of the thinnest sections of the aquifer were in the eastern part of the study area and some of the thickest sections were in the Pecos, Monument Draw, and Belding-Coyanosa trough areas. Normal-fault zones, which formed as growth and collapse features as sediments were deposited along the margins of more resistant rocks and as overlying sediments collapsed into the voids created by the dissolution of Permian-age evaporite deposits, were delineated based on the interpretation of hydrostratigraphic cross sections. The lowest aquifer transmissivity values were measured in the eastern part of the study area; the highest transmissivity values were

  20. Numerical simulation of groundwater flow at Puget Sound Naval Shipyard, Naval Base Kitsap, Bremerton, Washington

    Science.gov (United States)

    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

  1. Hydrogeologic Framework Model for the Saturated Zone Site Scale flow and Transport Model

    Energy Technology Data Exchange (ETDEWEB)

    T. Miller

    2004-11-15

    The purpose of this report is to document the 19-unit, hydrogeologic framework model (19-layer version, output of this report) (HFM-19) with regard to input data, modeling methods, assumptions, uncertainties, limitations, and validation of the model results in accordance with AP-SIII.10Q, Models. The HFM-19 is developed as a conceptual model of the geometric extent of the hydrogeologic units at Yucca Mountain and is intended specifically for use in the development of the ''Saturated Zone Site-Scale Flow Model'' (BSC 2004 [DIRS 170037]). Primary inputs to this model report include the GFM 3.1 (DTN: MO9901MWDGFM31.000 [DIRS 103769]), borehole lithologic logs, geologic maps, geologic cross sections, water level data, topographic information, and geophysical data as discussed in Section 4.1. Figure 1-1 shows the information flow among all of the saturated zone (SZ) reports and the relationship of this conceptual model in that flow. The HFM-19 is a three-dimensional (3-D) representation of the hydrogeologic units surrounding the location of the Yucca Mountain geologic repository for spent nuclear fuel and high-level radioactive waste. The HFM-19 represents the hydrogeologic setting for the Yucca Mountain area that covers about 1,350 km2 and includes a saturated thickness of about 2.75 km. The boundaries of the conceptual model were primarily chosen to be coincident with grid cells in the Death Valley regional groundwater flow model (DTN: GS960808312144.003 [DIRS 105121]) such that the base of the site-scale SZ flow model is consistent with the base of the regional model (2,750 meters below a smoothed version of the potentiometric surface), encompasses the exploratory boreholes, and provides a framework over the area of interest for groundwater flow and radionuclide transport modeling. In depth, the model domain extends from land surface to the base of the regional groundwater flow model (D'Agnese et al. 1997 [DIRS 100131], p 2). For the site

  2. Hydrogeologic Framework Model for the Saturated Zone Site Scale flow and Transport Model

    International Nuclear Information System (INIS)

    Miller, T.

    2004-01-01

    The purpose of this report is to document the 19-unit, hydrogeologic framework model (19-layer version, output of this report) (HFM-19) with regard to input data, modeling methods, assumptions, uncertainties, limitations, and validation of the model results in accordance with AP-SIII.10Q, Models. The HFM-19 is developed as a conceptual model of the geometric extent of the hydrogeologic units at Yucca Mountain and is intended specifically for use in the development of the ''Saturated Zone Site-Scale Flow Model'' (BSC 2004 [DIRS 170037]). Primary inputs to this model report include the GFM 3.1 (DTN: MO9901MWDGFM31.000 [DIRS 103769]), borehole lithologic logs, geologic maps, geologic cross sections, water level data, topographic information, and geophysical data as discussed in Section 4.1. Figure 1-1 shows the information flow among all of the saturated zone (SZ) reports and the relationship of this conceptual model in that flow. The HFM-19 is a three-dimensional (3-D) representation of the hydrogeologic units surrounding the location of the Yucca Mountain geologic repository for spent nuclear fuel and high-level radioactive waste. The HFM-19 represents the hydrogeologic setting for the Yucca Mountain area that covers about 1,350 km2 and includes a saturated thickness of about 2.75 km. The boundaries of the conceptual model were primarily chosen to be coincident with grid cells in the Death Valley regional groundwater flow model (DTN: GS960808312144.003 [DIRS 105121]) such that the base of the site-scale SZ flow model is consistent with the base of the regional model (2,750 meters below a smoothed version of the potentiometric surface), encompasses the exploratory boreholes, and provides a framework over the area of interest for groundwater flow and radionuclide transport modeling. In depth, the model domain extends from land surface to the base of the regional groundwater flow model (D'Agnese et al. 1997 [DIRS 100131], p 2). For the site-scale SZ flow model, the HFM

  3. GEOCHEMICAL AND ISOTOPIC CONSTRAINTS ON GROUND-WATER FLOW DIRECTIONS, MIXING AND RECHARGE AT YUCCA MOUNTAIN, NEVADA

    International Nuclear Information System (INIS)

    A. Meijer; E. Kwicklis

    2000-01-01

    This analysis is governed by the Office of Civilian Radioactive Waste Management (OCRWM) Analysis and Modeling Report Development Plan entitled ''Geochemical and Isotopic Constraints on Groundwater Flow Directions, Mixing and Recharge at Yucca Mountain'' (CRWMS M and O 1999a). As stated in this Development Plan, the purpose of the work is to provide an analysis of groundwater recharge rates, flow directions and velocities, and mixing proportions of water from different source areas based on groundwater geochemical and isotopic data. The analysis of hydrochemical and isotopic data is intended to provide a basis for evaluating the hydrologic system at Yucca Mountain independently of analyses based purely on hydraulic arguments. Where more than one conceptual model for flow is possible, based on existing hydraulic data, hydrochemical and isotopic data may be useful in eliminating some of these conceptual models. This report documents the use of geochemical and isotopic data to constrain rates and directions of groundwater flow near Yucca Mountain and the timing and magnitude of recharge in the Yucca Mountain vicinity. The geochemical and isotopic data are also examined with regard to the possible dilution of groundwater recharge from Yucca Mountain by mixing with groundwater downgradient from the potential repository site. Specifically, the primary tasks of this report, as listed in the AMR Development Plan (CRWMS M and O 1999a), consist of the following: (1) Compare geochemical and isotopic data for perched and pore water in the unsaturated zone with similar data from the saturated zone to determine if local recharge is present in the regional groundwater system; (2) Determine the timing of the recharge from stable isotopes such as deuterium ( 2 H) and oxygen-18 ( 18 O), which are known to vary over time as a function of climate, and from radioisotopes such as carbon-14 ( 14 C) and chlorine-36 ( 36 Cl); (3) Determine the magnitude of recharge from relatively

  4. Saturated Zone Flow and Transport Expert Elicitation Project

    Energy Technology Data Exchange (ETDEWEB)

    Coppersmith, Kevin J.; Perman, Roseanne C.

    1998-01-01

    This report presents results of the Saturated Zone Flow and Transport Expert Elicitation (SZEE) project for Yucca Mountain, Nevada. This project was sponsored by the US Department of Energy (DOE) and managed by Geomatrix Consultants, Inc. (Geomatrix), for TRW Environmental Safety Systems, Inc. The DOE's Yucca Mountain Site Characterization Project (referred to as the YMP) is intended to evaluate the suitability of the site for construction of a mined geologic repository for the permanent disposal of spent nuclear fuel and high-level radioactive waste. The SZEE project is one of several that involve the elicitation of experts to characterize the knowledge and uncertainties regarding key inputs to the Yucca Mountain Total System Performance Assessment (TSPA). The objective of the current project was to characterize the uncertainties associated with certain key issues related to the saturated zone system in the Yucca Mountain area and downgradient region. An understanding of saturated zone processes is critical to evaluating the performance of the potential high-level nuclear waste repository at Yucca Mountain. A major goal of the project was to capture the uncertainties involved in assessing the saturated flow processes, including uncertainty in both the models used to represent the physical processes controlling saturated zone flow and transport, and the parameter values used in the models. So that the analysis included a wide range of perspectives, multiple individual judgments were elicited from members of an expert panel. The panel members, who were experts from within and outside the Yucca Mountain project, represented a range of experience and expertise. A deliberate process was followed in facilitating interactions among the experts, in training them to express their uncertainties, and in eliciting their interpretations. The resulting assessments and probability distributions, therefore, provide a reasonable aggregate representation of the knowledge and

  5. 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

  6. Seismic effects on bedrock and underground constructions. A literature survey of damage on constructions; Changes in groundwater levels and flow; Changes in chemistry in groundwater and gases

    International Nuclear Information System (INIS)

    Roeshoff, Kennert.

    1989-06-01

    This report is a literature review of direct and indirect effects of earthquakes on underground constructions as tunnels, caverns and mines. The direct damage will cause vibrations, shaking and displacement, which may lead to partial or total destruction of the underground facility. Damage caused by shaking has been reported in several studies, and several hundreds of events have been reported both from mines and tunnels. These reports are mainly from active earthquake areas. There are very few reports of damage caused by displacements on an existing fault. The damage, which may be severe, is generally concentrated to the vicinity of the fault zone. The report also includes a review of the effects caused by earthquakes on groundwater level, flow, pressure, chemistry and constituents in the ground. Such changes are mainly reported from studies in wells near active faults. The interesting coupling of changes in groundwater characteristics around an underground construction is, unfortunately, very seldom reported. The groundwater level and pressure changes are discussed in Chapter 4. The bases for this part of the review is taken from the Alaska earthquake 1964. Other observations are reported from wells and reservoirs located near existing faults. Changes of the geochemistry in groundwater and soil gases are reviewed in Chapter 4. The mechanisms of seismochemical anomalies are discussed and examples of short and long term monitoring are given from USA, Soviet Union and China. Gases in ground water and soil is reported in Chapter 5. Radon is so far one of the most studied species and its variation in short, medium and long term with seismic activity is rather well understood. Other gases or isotopes that have been studied include helium, carbon dioxide, hydrogen, argon and methane, radium and uranium. The paper also includes same statements for repository design based on the result of the review. (81 refs.)

  7. Groundwater flow and water budget in the surficial and Floridan aquifer systems in east-central Florida

    Science.gov (United States)

    Sepulveda, Nicasio; Tiedeman, Claire; O'Reilly, Andrew M.; Davis, Jeffrey B.; Burger, Patrick

    2012-01-01

    A numerical transient model of the surficial and Floridan aquifer systems in east-central Florida was developed to (1) increase the understanding of water exchanges between the surficial and the Floridan aquifer systems, (2) assess the recharge rates to the surficial aquifer system from infiltration through the unsaturated zone and (3) obtain a simulation tool that could be used by water-resource managers to assess the impact of changes in groundwater withdrawals on spring flows and on the potentiometric surfaces of the hydrogeologic units composing the Floridan aquifer system. The hydrogeology of east-central Florida was evaluated and used to develop and calibrate the groundwater flow model, which simulates the regional fresh groundwater flow system. The U.S. Geological Survey three-dimensional groundwater flow model, MODFLOW-2005, was used to simulate transient groundwater flow in the surficial, intermediate, and Floridan aquifer systems from 1995 to 2006. The East-Central Florida Transient model encompasses an actively simulated area of about 9,000 square miles. Although the model includes surficial processes-rainfall, irrigation, evapotranspiration (ET), runoff, infiltration, lake water levels, and stream water levels and flows-its primary purpose is to characterize and refine the understanding of groundwater flow in the Floridan aquifer system. Model-independent estimates of the partitioning of rainfall into ET, streamflow, and aquifer recharge are provided from a water-budget analysis of the surficial aquifer system. The interaction of the groundwater flow system with the surface environment was simulated using the Green-Ampt infiltration method and the MODFLOW-2005 Unsaturated-Zone Flow, Lake, and Streamflow-Routing Packages. The model is intended to simulate the part of the groundwater system that contains freshwater. The bottom and lateral boundaries of the model were established at the estimated depths where the chloride concentration is 5,000 milligrams

  8. Channel Incision Driven by Suburbanization: Impacts to Riparian Groundwater Flow and Overbank Flow Frequency

    Science.gov (United States)

    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

  9. Delineation of a wellhead protection zone and determination of flowpaths from potential groundwater contaminant source areas at Camp Ripley, Little Falls, Minnesota.

    Energy Technology Data Exchange (ETDEWEB)

    Quinn, J. J.; Environmental Science Division

    2006-12-22

    Groundwater at Camp Ripley, Minnesota, is recharged both on post and off site and discharged to rivers, wetlands, and pumping wells. The subsurface geologic materials have a wide range of permeabilities and are arranged in a complex fashion as a result of the region's multiple glacial advances. Correlation of individual glacial geologic units is difficult, even between nearby boreholes, because of the heterogeneities in the subsurface. This report documents the creation of a numerical model of groundwater flow for Camp Ripley and hydrologically related areas to the west and southwest. The model relies on a hydrogeological conceptual model built on the findings of a University of Minnesota-Duluth drilling and sampling program conducted in 2001. Because of the site's stratigraphic complexity, a geostatistical approach was taken to handle the uncertainty of the subsurface correlation. The U.S. Geological Survey's MODFLOW code was used to create the steady-state model, which includes input data from a variety of sources and is calibrated to water levels in monitoring wells across much of the site. This model was used for several applications. Wellhead protection zones were delineated for on-site production wells H, L, and N. The zones were determined on the basis of a probabilistic assessment of the groundwater captured by these wells; the assessment, in turn, had been based on multiple realizations of the study area's stratigraphy and groundwater flowfield. An additional application of the model was for estimating flowpaths and times of travel for groundwater at Camp Ripley's range areas and waste management facilities.

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

    Science.gov (United States)

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

    2012-01-01

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

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

    Science.gov (United States)

    Juckem, Paul F.

    2009-01-01

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

  12. Groundwater management in coastal zones and on islands in crystalline bedrock areas of Sweden

    Science.gov (United States)

    Banzhaf, Stefan; Ekström, Linda Louise; Ljungkvist, Andreas; Granberg, Maria; Merisalu, Johanna; Pokorny, Sebastian; Barthel, Roland

    2017-04-01

    Groundwater problems in coastal regions are usually not associated with the sparsely populated shores of water-rich Scandinavia. However, the combination of geology and the specific conditions of water usage create challenges even there. Along the Swedish coast, much of the groundwater occurs in fractured bedrock or in relatively small, shallow, and isolated quaternary sedimentary formations. Those aquifers cannot provide water to larger permanent settlements and are thus neither useful for the public water supply nor have previously received much attention from water authorities or researchers. However, of the 450,000 private wells in Sweden, many are located in coastal areas or on islands, creating pressure on groundwater resources in summer months as periods with low or no natural groundwater recharge. In view of the increasing water demand, as well as the awareness of environmental impacts and climate change, Swedish municipalities now recognize groundwater usage in coastal areas is a major concern. Here, we present the results of an investigation on the "Koster" archipelago which forms a microcosm of coastal zone groundwater problems in Sweden. Koster's geology is dominated by fractured, crystalline bedrock with occasional shallow quaternary deposits in between. With around 300 permanent residents, and up to 6,000 summer guests in peak holiday season, the existing water supply based on 800 private wells is at its limit. Water availability forms an obstacle to future development and the current mode of operation is unsustainable. Therefore, the municipality must decide how to secure future water supply which involves complex legal problems, as well as social, cultural, economic, hydrogeological, and environmental questions. As there are no observation wells on the islands, we used approximately 220 of the 800 wells (65% dug and shallow, 35% drilled and up to 120m deep) for our monitoring. Additionally, water samples were collected by property owners on four

  13. Improved Characterization of Groundwater Flow in Heterogeneous Aquifers Using Granular Polyacrylamide (PAM) Gel as Temporary Grout

    Science.gov (United States)

    Klepikova, Maria V.; Roques, Clement; Loew, Simon; Selker, John

    2018-02-01

    The range of options for investigation of hydraulic behavior of aquifers from boreholes has been limited to rigid, cumbersome packers, and inflatable sleeves. Here we show how a new temporary borehole sealing technique using soft grains of polyacrylamide (PAM) gel as a sealing material can be used to investigate natural groundwater flow dynamics and discuss other possible applications of the technology. If no compressive stress is applied, the gel packing, with a permeability similar to open gravel, suppresses free convection, allowing for local temperature measurements and chemical sampling through free-flowing gel packing. Active heating laboratory and field experiments combined with temperature measurements along fiber optic cables were conducted in water-filled boreholes and boreholes filled with soft grains of polyacrylamide gel. The gel packing is shown to minimize the effect of free convection within the well column and enable detection of thin zones of relatively high or low velocity in a highly transmissive alluvial aquifer, thus providing a significant improvement compared to temperature measurements in open boreholes. Laboratory experiments demonstrate that under modest compressive stress to the gel media the permeability transitions from highly permeable to nearly impermeable grouting. Under this configuration the gel packing could potentially allow for monitoring local response pressure from the formation with all other locations in the borehole hydraulically isolated.

  14. Acid-base status of soils in groundwater discharge zones — relation to surface water acidification

    Science.gov (United States)

    Norrström, Ann Catrine

    1995-08-01

    Critical load calculations have suggested that groundwater at depth of 2 m in Sweden is very sensitive to acid load. As environmental isotope studies have shown that most of the runoff in streams has passed through the soil, there is a risk in the near future of accelerated acidification of surface waters. To assess the importance of the last soil horizon of contact before discharge, the upper 0-0.2m of soils in seven discharge zones were analysed for pools of base cations, acidity and base saturation. The sites were about 3-4 m 2 in size and selected from two catchments exposed to different levels of acid deposition. The soils in the seven sites had high concentrations of exchangeable base cations and consequently high base saturation. The high correlation ( r2 = 0.74) between base saturation in the soils of the discharge zones and mean pH of the runoff waters suggested that the discharge zone is important for surface water acidification. The high pool of exchangeable base cations will buffer initially against the acid load. As the cation exchange capacity (meq dm -3) and base saturation were lower in the sites from the catchment receiving lower deposition, these streams may be more vulnerable to acidification in the near future. The high concentration of base cations in non-exchangeable fractions may also buffer against acidification as it is likely that some of these pools will become exchangeable with time.

  15. An inverse modeling approach to estimate groundwater flow and transport model parameters at a research site at Vandenberg AFB, CA

    Science.gov (United States)

    Rasa, E.; Foglia, L.; Mackay, D. M.; Ginn, T. R.; Scow, K. M.

    2009-12-01

    A numerical groundwater fate and transport model was developed for analyses of data from field experiments evaluating the impacts of ethanol on the natural attenuation of benzene, toluene, ethylbenzene, and xylenes (BTEX) and methyl tert-butyl ether (MTBE) at Vandenberg Air Force Base, Site 60. We used the U.S. Geological Survey (USGS) groundwater flow (MODFLOW2000) and transport (MT3DMS) models in conjunction with the USGS universal inverse modeling code (UCODE) to jointly determine flow and transport parameters using bromide tracer data from multiple experiments in the same location. The key flow and transport parameters include hydraulic conductivity of aquifer and aquitard layers, porosity, and transverse and longitudinal dispersivity. Aquifer and aquitard layers were assumed homogenous in this study. Therefore, the calibration parameters were not spatially variable within each layer. A total of 162 monitoring wells in seven transects perpendicular to the mean flow direction were monitored over the course of ten months, resulting in 1,766 bromide concentration data points and 149 head values used as observations for the inverse modeling. The results showed the significance of the concentration observation data in predicting the flow model parameters and indicated the sensitivity of the hydraulic conductivity of different zones in the aquifer including the excavated former contaminant zone. The model has already been used to evaluate alternative designs for further experiments on in situ bioremediation of the tert-butyl alcohol (TBA) plume remaining at the site. We describe the recent applications of the model and future work, including adding reaction submodels to the calibrated flow model.

  16. 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.

  17. 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.

  18. Effects of groundwater-flow paths on nitrate concentrations across two riparian forest corridors

    Science.gov (United States)

    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.

  19. Groundwater recharge and flow on Montserrat, West Indies: Insights from groundwater dating

    OpenAIRE

    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...

  20. TECHNICAL BASIS FOR EVALUATING SURFACE BARRIERS TO PROTECT GROUNDWATER FROM DEEP VADOSE ZONE CONTAMINATION

    International Nuclear Information System (INIS)

    Fayer, J.M.; Freedman, V.L.; Ward, A.L.; Chronister, G.B.

    2010-01-01

    tasks to achieve those outcomes. Full understanding of contaminant behavior in the deep vadose zone is constrained by four key data gaps: limited access; limited data; limited time; and the lack of an accepted predictive capability for determining whether surface barriers can effectively isolate deep vadose zone contaminants. Activities designed to fill these data gaps need to have these outcomes: (1) common evaluation methodology that provides a clear, consistent, and defensible basis for evaluating groundwater impacts caused by placement of a surface barrier above deep vadose zone contamination; (2) deep vadose zone data that characterize the lithology, the spatial distribution of moisture and contaminants, the physical, chemical, and biological process that affect the mobility of each contaminant, and the impacts to the contaminants following placement of a surface barrier; (3) subsurface monitoring to provide subsurface characterization of initial conditions and changes that occur during and following remediation activities; and (4) field observations that span years to decades to validate the evaluation methodology. A set of six proposed tasks was identified to provide information needed to address the above outcomes. The proposed tasks are: (1) Evaluation Methodology - Develop common evaluation methodology that will provide a clear, consistent, and defensible basis for evaluating groundwater impacts caused by placement of a surface barrier above deep vadose zone contamination. (2) Case Studies - Conduct case studies to demonstrate the applicability ofthe common evaluation methodology and provide templates for subsequent use elsewhere. Three sites expected to have conditions that would yield valuable information and experience pertinent to deep vadose zone contamination were chosen to cover a range of conditions. The sites are BC Cribs and Trenches, U Plant Cribs, and the T Farm Interim Cover. (3) Subsurface Monitoring Technologies - Evaluate minimally invasive

  1. Numerical groundwater-flow modeling to evaluate potential effects of pumping and recharge: implications for sustainable groundwater management in the Mahanadi delta region, India

    Science.gov (United States)

    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.

  2. 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)

  3. Numerical modeling of ground-water flow systems in the vicinity of the reference repository location, Hanford Site, Washington

    International Nuclear Information System (INIS)

    Davis, P.; Beyeler, W.; Logsdon, M.; Coleman, N.; Brinster, K.

    1989-04-01

    This report documents south-central Washington State's Pasco Basin ground-water modeling studies. This work was done to support the NRC's review of hydrogeologic studies under the Department of Energy's (DOE) Basalt Waste Isolation Project. The report provides a brief overview of the geology, hydrology, and hydrochemistry of the Pasco Basin as a basis for the evaluation of previous conceptual and numerical ground-water flow models of the region. Numerical models were developed to test new conceptual models of the site and to provide a means of evaluating the Department of Energy's performance assessments and proposed hydrologic testing. Regional ground-water flow modeling of an area larger than the Pasco Basin revealed that current concepts on the existence and behavior of a hydrologic barrier west of the proposed repository location are inconsistent with available data. This modeling also demonstrated that the measured pattern of hydraulic heads cannot be produced with a model that (1) has uniform layer properties over the entire domain; (2) has zones of large conductivity associated with anticlinal structures; or (3) includes recharge from the industrial disposal ponds. Adequate representation of the measured hydraulic heads was obtained with a model that contained regions of larger hydraulic conductivity that corresponded to the presence of sedimentary interbeds. In addition, a detailed model of a region smaller than the Pasco Basin was constructed to provide the NRC staff with the ability to analyze proposed Department of Energy hydrologic tests. 62 refs., 145 figs., 18 tabs

  4. Evaluating Ecosystem Services for Reducing Groundwater Nitrate Contamination: Nitrate Attenuation in the Unsaturated and Saturated Zones

    Science.gov (United States)

    Wang, J.

    2013-12-01

    Nitrates are the most common type of groundwater contamination in agricultural regions. Environmental policies targeting nitrates have focused on input control (e.g., restricted fertilizer application), intermediate loads control (e.g., reduce nitrate leached from crop fields), and final loads control (e.g., reduce catchment nitrate loads). Nitrate loads can be affected by hydrological processes in both unsaturated and saturated zones. Although many of these processes have been extensively investigated in literature, they are commonly modeled as exogenous to farm management. A couple of recent studies by scientists from the Lawrence Livermore National Laboratory show that in some situations nitrate attenuation processes in the unsaturated/saturated zone, particularly denitrification, can be intensified by certain management practices to mitigate nitrate loads. Therefore, these nitrate attenuation processes can be regarded as a set of ecosystem services that farmers can take advantage of to reduce their cost of complying with environmental policies. In this paper, a representative California dairy farm is used as a case study to show how such ecosystem attenuation services can be framed within the farm owner's decision-making framework as an option for reducing groundwater nitrate contamination. I develop an integrated dynamic model, where the farmer maximizes discounted net farm profit over multiple periods subject to environmental regulations. The model consists of three submodels: animal-waste-crop, hydrologic, and economic model. In addition to common choice variables such as irrigation, fertilization, and waste disposal options, the farmer can also endogenously choose from three water sources: surface water, deep groundwater (old groundwater in the deep aquifer that is not affected by farm effluent in the short term), and shallow groundwater (drainage water that can be recycled via capture wells at the downstream end of the farm). The capture wells not only

  5. 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

  6. Generation of 3-D hydrostratigraphic zones from dense airborne electromagnetic data to assess groundwater model prediction error

    Science.gov (United States)

    Christensen, N. K.; Minsley, B. J.; Christensen, S.

    2017-02-01

    We present a new methodology to combine spatially dense high-resolution airborne electromagnetic (AEM) data and sparse borehole information to construct multiple plausible geological structures using a stochastic approach. The method developed allows for quantification of the performance of groundwater models built from different geological realizations of structure. Multiple structural realizations are generated using geostatistical Monte Carlo simulations that treat sparse borehole lithological observations as hard data and dense geophysically derived structural probabilities as soft data. Each structural model is used to define 3-D hydrostratigraphical zones of a groundwater model, and the hydraulic parameter values of the zones are estimated by using nonlinear regression to fit hydrological data (hydraulic head and river discharge measurements). Use of the methodology is demonstrated for a synthetic domain having structures of categorical deposits consisting of sand, silt, or clay. It is shown that using dense AEM data with the methodology can significantly improve the estimated accuracy of the sediment distribution as compared to when borehole data are used alone. It is also shown that this use of AEM data can improve the predictive capability of a calibrated groundwater model that uses the geological structures as zones. However, such structural models will always contain errors because even with dense AEM data it is not possible to perfectly resolve the structures of a groundwater system. It is shown that when using such erroneous structures in a groundwater model, they can lead to biased parameter estimates and biased model predictions, therefore impairing the model's predictive capability.

  7. Generation of 3-D hydrostratigraphic zones from dense airborne electromagnetic data to assess groundwater model prediction error

    Science.gov (United States)

    Christensen, Nikolaj K; Minsley, Burke J.; Christensen, Steen

    2017-01-01

    We present a new methodology to combine spatially dense high-resolution airborne electromagnetic (AEM) data and sparse borehole information to construct multiple plausible geological structures using a stochastic approach. The method developed allows for quantification of the performance of groundwater models built from different geological realizations of structure. Multiple structural realizations are generated using geostatistical Monte Carlo simulations that treat sparse borehole lithological observations as hard data and dense geophysically derived structural probabilities as soft data. Each structural model is used to define 3-D hydrostratigraphical zones of a groundwater model, and the hydraulic parameter values of the zones are estimated by using nonlinear regression to fit hydrological data (hydraulic head and river discharge measurements). Use of the methodology is demonstrated for a synthetic domain having structures of categorical deposits consisting of sand, silt, or clay. It is shown that using dense AEM data with the methodology can significantly improve the estimated accuracy of the sediment distribution as compared to when borehole data are used alone. It is also shown that this use of AEM data can improve the predictive capability of a calibrated groundwater model that uses the geological structures as zones. However, such structural models will always contain errors because even with dense AEM data it is not possible to perfectly resolve the structures of a groundwater system. It is shown that when using such erroneous structures in a groundwater model, they can lead to biased parameter estimates and biased model predictions, therefore impairing the model's predictive capability.

  8. Influences of groundwater extraction on flow dynamics and arsenic levels in the western Hetao Basin, Inner Mongolia, China

    Science.gov (United States)

    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.

  9. A study on the groundwater flow system for deep geological disposal of high level radioactive waste in Korea

    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)

  10. The interaction between the unsaturated zone, aquifer, and stream during a period of groundwater withdrawal

    DEFF Research Database (Denmark)

    Poulsen, Søren Erbs; Christensen, Steen; Rasmussen, Keld Rømer

    2011-01-01

    drainage responses to water-table drawdown. The responses can be sufficiently modeled by estimating the specific yield and five exponential time constants of a Moench/Boulton type model of delayed drainage. The average specific yield is thus estimated to 0.24 which is in agreement with previous small scale......; in the second case the estimate (0.17) is in better agreement with core and previous estimates (0.24). The analysis indicates that relatively fast drainage, and the existence of two drawdown dependent sources of groundwater recharge (the storage and the stream), complicates pumping test design to obtain unique...... parameter estimation. The analysis supports that an essential factor in parameter estimation by pumping test analysis for (at least some) unconfined aquifers is the use of a model that accounts for time-varying drainage from the vadose zone. Finally, when predicting stream depletion beyond 1. day of pumping...

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

    Science.gov (United States)

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

    2017-12-01

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

  12. Seasonal arsenic accumulation in stream sediments at a groundwater discharge zone.

    Science.gov (United States)

    MacKay, Allison A; Gan, Ping; Yu, Ran; Smets, Barth F

    2014-01-21

    Seasonal changes in arsenic and iron accumulation rates were examined in the sediments of a brook that receives groundwater discharges of arsenic and reduced iron. Clean glass bead columns were deployed in sediments for known periods over the annual hydrologic cycle to monitor changes in arsenic and iron concentrations in bead coatings. The highest accumulation rates occurred during the dry summer period (July-October) when groundwater discharges were likely greatest at the sample locations. The intermediate flow period (October-March), with higher surface water levels, was associated with losses of arsenic and iron from bead column coatings at depths below 2-6 cm. Batch incubations indicated iron releases from solids to be induced by biological reduction of iron (oxy)hydroxide solids. Congruent arsenic releases during incubation were limited by the high arsenic sorption capacity (0.536 mg(As)/mg(Fe)) of unreacted iron oxide solids. The flooded spring (March-June) with high surface water flows showed the lowest arsenic and iron accumulation rates in the sediments. Comparisons of accumulation rates across a shoreline transect were consistent with greater rates at regions exposed above surface water levels for longer times and greater losses at locations submerged below surface water. Iron (oxy)hydroxide solids in the shallowest sediments likely serve as a passive barrier to sorb arsenic released to pore water at depth by biological iron reduction.

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

    International Nuclear Information System (INIS)

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

    1991-10-01

    This report describes a simulation study of groundwater flow and radionuclide transport from disposal at the NRC licensed waste disposal facility in West Valley, New York. A transient, precipitation driven, flow model of the near-surface fractured till layer and underlying unweathered till was developed and calibrated against observed inflow data into a recently constructed interceptor trench for the period March--May 1990. The results sugges