WorldWideScience

Sample records for groundwater gradients representing

  1. Groundwater biofilm dynamics grown in situ along a nutrient gradient.

    Science.gov (United States)

    Williamson, Wendy M; Close, Murray E; Leonard, Margaret M; Webber, Judith B; Lin, Susan

    2012-01-01

    This paper describes the in situ response of groundwater biofilms in an alluvial gravel aquifer system on the Canterbury Plains, New Zealand. Biofilms were developed on aquifer gravel, encased in fine mesh bags and suspended in protective columns in monitoring wells for at least 20 weeks. Four sites were selected in the same groundwater system where previous analyses indicated a gradient of increasing nitrate down the hydraulic gradient from Sites 1 to 4. Measurements during the current study classified the groundwater as oligotrophic. Biofilm responses to the nutrient gradients were assessed using bioassays, with biomass determined using protein and cellular and nucleic acid staining and biofilm activity using enzyme assays for lipid, carbohydrate, phosphate metabolism, and cell viability. In general, biofilm activity decreased as nitrate levels increased from Sites 1 to 4, with the opposite relationship for carbon and phosphorus concentrations. These results showed that the groundwater system supported biofilm growth and that the upper catchment supported efficient and productive biofilms (high ratio of activity per unit biomass). © 2012, Institute of Environmental Science & Research Ltd (ESR). Ground Water © 2012, National Ground Water Association.

  2. Improving large-scale groundwater models by considering fossil gradients

    Science.gov (United States)

    Schulz, Stephan; Walther, Marc; Michelsen, Nils; Rausch, Randolf; Dirks, Heiko; Al-Saud, Mohammed; Merz, Ralf; Kolditz, Olaf; Schüth, Christoph

    2017-05-01

    Due to limited availability of surface water, many arid to semi-arid countries rely on their groundwater resources. Despite the quasi-absence of present day replenishment, some of these groundwater bodies contain large amounts of water, which was recharged during pluvial periods of the Late Pleistocene to Early Holocene. These mostly fossil, non-renewable resources require different management schemes compared to those which are usually applied in renewable systems. Fossil groundwater is a finite resource and its withdrawal implies mining of aquifer storage reserves. Although they receive almost no recharge, some of them show notable hydraulic gradients and a flow towards their discharge areas, even without pumping. As a result, these systems have more discharge than recharge and hence are not in steady state, which makes their modelling, in particular the calibration, very challenging. In this study, we introduce a new calibration approach, composed of four steps: (i) estimating the fossil discharge component, (ii) determining the origin of fossil discharge, (iii) fitting the hydraulic conductivity with a pseudo steady-state model, and (iv) fitting the storage capacity with a transient model by reconstructing head drawdown induced by pumping activities. Finally, we test the relevance of our approach and evaluated the effect of considering or ignoring fossil gradients on aquifer parameterization for the Upper Mega Aquifer (UMA) on the Arabian Peninsula.

  3. Quantifying groundwater dependency of riparian surface hydrologic features using the exit gradient

    Science.gov (United States)

    This study examines groundwater exit gradients as a way to quantify groundwater interactions with surface water. We calibrated high resolution groundwater models for the basin fill sediments in the lower Calapooia watershed, Oregon, using data collected between 1928--2000. The e...

  4. Testing a groundwater sampling tool: Are the samples representative?

    International Nuclear Information System (INIS)

    Kaback, D.S.; Bergren, C.L.; Carlson, C.A.; Carlson, C.L.

    1989-01-01

    A ground water sampling tool, the HydroPunch trademark, was tested at the Department of Energy's Savannah River Site in South Carolina to determine if representative ground water samples could be obtained without installing monitoring wells. Chemical analyses of ground water samples collected with the HydroPunch trademark from various depths within a borehole were compared with chemical analyses of ground water from nearby monitoring wells. The site selected for the test was in the vicinity of a large coal storage pile and a coal pile runoff basin that was constructed to collect the runoff from the coal storage pile. Existing monitoring wells in the area indicate the presence of a ground water contaminant plume that: (1) contains elevated concentrations of trace metals; (2) has an extremely low pH; and (3) contains elevated concentrations of major cations and anions. Ground water samples collected with the HydroPunch trademark provide in excellent estimate of ground water quality at discrete depths. Groundwater chemical data collected from various depths using the HydroPunch trademark can be averaged to simulate what a screen zone in a monitoring well would sample. The averaged depth-discrete data compared favorably with the data obtained from the nearby monitoring wells

  5. Groundwater Flow and Thermal Modeling to Support a Preferred Conceptual Model for the Large Hydraulic Gradient North of Yucca Mountain

    International Nuclear Information System (INIS)

    McGraw, D.; Oberlander, P.

    2007-01-01

    The purpose of this study is to report on the results of a preliminary modeling framework to investigate the causes of the large hydraulic gradient north of Yucca Mountain. This study builds on the Saturated Zone Site-Scale Flow and Transport Model (referenced herein as the Site-scale model (Zyvoloski, 2004a)), which is a three-dimensional saturated zone model of the Yucca Mountain area. Groundwater flow was simulated under natural conditions. The model framework and grid design describe the geologic layering and the calibration parameters describe the hydrogeology. The Site-scale model is calibrated to hydraulic heads, fluid temperature, and groundwater flowpaths. One area of interest in the Site-scale model represents the large hydraulic gradient north of Yucca Mountain. Nearby water levels suggest over 200 meters of hydraulic head difference in less than 1,000 meters horizontal distance. Given the geologic conceptual models defined by various hydrogeologic reports (Faunt, 2000, 2001; Zyvoloski, 2004b), no definitive explanation has been found for the cause of the large hydraulic gradient. Luckey et al. (1996) presents several possible explanations for the large hydraulic gradient as provided below: The gradient is simply the result of flow through the upper volcanic confining unit, which is nearly 300 meters thick near the large gradient. The gradient represents a semi-perched system in which flow in the upper and lower aquifers is predominantly horizontal, whereas flow in the upper confining unit would be predominantly vertical. The gradient represents a drain down a buried fault from the volcanic aquifers to the lower Carbonate Aquifer. The gradient represents a spillway in which a fault marks the effective northern limit of the lower volcanic aquifer. The large gradient results from the presence at depth of the Eleana Formation, a part of the Paleozoic upper confining unit, which overlies the lower Carbonate Aquifer in much of the Death Valley region. The

  6. The suitability of using dissolved gases to determine groundwater discharge to high gradient streams

    Science.gov (United States)

    Gleeson, Tom; Manning, Andrew H.; Popp, Andrea; Zane, Mathew; Clark, Jordan F.

    2018-01-01

    Determining groundwater discharge to streams using dissolved gases is known to be useful over a wide range of streamflow rates but the suitability of dissolved gas methods to determine discharge rates in high gradient mountain streams has not been sufficiently tested, even though headwater streams are critical as ecological habitats and water resources. The aim of this study is to test the suitability of using dissolved gases to determine groundwater discharge rates to high gradient streams by field experiments in a well-characterized, high gradient mountain stream and a literature review. At a reach scale (550 m) we combined stream and groundwater radon activity measurements with an in-stream SF6 tracer test. By means of numerical modeling we determined gas exchange velocities and derived very low groundwater discharge rates (∼15% of streamflow). These groundwater discharge rates are below the uncertainty range of physical streamflow measurements and consistent with temperature, specific conductance and streamflow measured at multiple locations along the reach. At a watershed-scale (4 km), we measured CFC-12 and δ18O concentrations and determined gas exchange velocities and groundwater discharge rates with the same numerical model. The groundwater discharge rates along the 4 km stream reach were highly variable, but were consistent with the values derived in the detailed study reach. Additionally, we synthesized literature values of gas exchange velocities for different stream gradients which show an empirical relationship that will be valuable in planning future dissolved gas studies on streams with various gradients. In sum, we show that multiple dissolved gas tracers can be used to determine groundwater discharge to high gradient mountain streams from reach to watershed scales.

  7. The suitability of using dissolved gases to determine groundwater discharge to high gradient streams

    Science.gov (United States)

    Gleeson, Tom; Manning, Andrew H.; Popp, Andrea; Zane, Matthew; Clark, Jordan F.

    2018-02-01

    Determining groundwater discharge to streams using dissolved gases is known to be useful over a wide range of streamflow rates but the suitability of dissolved gas methods to determine discharge rates in high gradient mountain streams has not been sufficiently tested, even though headwater streams are critical as ecological habitats and water resources. The aim of this study is to test the suitability of using dissolved gases to determine groundwater discharge rates to high gradient streams by field experiments in a well-characterized, high gradient mountain stream and a literature review. At a reach scale (550 m) we combined stream and groundwater radon activity measurements with an in-stream SF6 tracer test. By means of numerical modeling we determined gas exchange velocities and derived very low groundwater discharge rates (∼15% of streamflow). These groundwater discharge rates are below the uncertainty range of physical streamflow measurements and consistent with temperature, specific conductance and streamflow measured at multiple locations along the reach. At a watershed-scale (4 km), we measured CFC-12 and δ18O concentrations and determined gas exchange velocities and groundwater discharge rates with the same numerical model. The groundwater discharge rates along the 4 km stream reach were highly variable, but were consistent with the values derived in the detailed study reach. Additionally, we synthesized literature values of gas exchange velocities for different stream gradients which show an empirical relationship that will be valuable in planning future dissolved gas studies on streams with various gradients. In sum, we show that multiple dissolved gas tracers can be used to determine groundwater discharge to high gradient mountain streams from reach to watershed scales.

  8. The Exit Gradient As a Measure of Groundwater Dependency of Watershed Ecosystem Services

    Science.gov (United States)

    Faulkner, B. R.; Canfield, T. J.; Justin, G. F.

    2014-12-01

    Flux of groundwater to surface water is often of great interest for the determination of the groundwater dependency of ecosystem services, such as maintenance of wetlands and of baseflow as a contributor to stream channel storage. It is difficult to measure. Most methods are based on coarse mass balance estimates or seepage meters. One drawback of these methods is they are not entirely spatially explicit. The exit gradient is commonly used in engineering studies of hydraulic structures affected by groundwater flow. It can be simply defined in the groundwater modeling context as the ratio of the difference between the computed head and the land surface elevation, for each computational cell, to the thickness of the cell, as it varies in space. When combined with calibrated groundwater flow models, it also has the potential to be useful in watershed scale evaluations of groundwater dependency in a spatially explicit way. We have taken advantage of calibrated models for the Calapooia watershed, Oregon, to map exit gradients for the watershed. Streams in the Calapooia are hydraulically well connected with groundwater. Not surprisingly, we found large variations in exit gradients between wet and dry season model runs, supporting the notion of stream expansion, as observed in the field, which may have a substantial influence on water quality. We have mapped the exit gradients in the wet and dry seasons, and compared them to regions which have been mapped in wetland surveys. Those classified as Palustrine types fell largest in the area of contribution from groundwater. In many cases, substantially high exit gradients, even on average, did not correspond to mapped wetland areas, yet nutrient retention ecosystem services may still be playing a role in these areas. The results also reinforce the notion of the importance of baseflow to maintenance of stream flow, even in the dry summer season in this Temperate/Mediterranean climate. Exit gradient mapping is a simple, yet

  9. Temperature logging of groundwater in bedrock wells for geothermal gradient characterization in New Hampshire, 2012

    Science.gov (United States)

    Degnan, James; Barker, Gregory; Olson, Neil; Wilder, Leland

    2012-01-01

    The U.S. Geological Survey, in cooperation with the New Hampshire Geological Survey, measured the fluid temperature of groundwater in deep bedrock wells in the State of New Hampshire in order to characterize geothermal gradients in bedrock. All wells selected for the study had low water yields, which correspond to low groundwater flow from fractures. This reduced the potential for flow-induced temperature changes that would mask the natural geothermal gradient in the bedrock. All the wells included in this study were privately owned, and permission to use the wells was obtained from homeowners before logging.

  10. Application of the conjugate-gradient method to ground-water models

    Science.gov (United States)

    Manteuffel, T.A.; Grove, D.B.; Konikow, Leonard F.

    1984-01-01

    The conjugate-gradient method can solve efficiently and accurately finite-difference approximations to the ground-water flow equation. An aquifer-simulation model using the conjugate-gradient method was applied to a problem of ground-water flow in an alluvial aquifer at the Rocky Mountain Arsenal, Denver, Colorado. For this application, the accuracy and efficiency of the conjugate-gradient method compared favorably with other available methods for steady-state flow. However, its efficiency relative to other available methods depends on the nature of the specific problem. The main advantage of the conjugate-gradient method is that it does not require the use of iteration parameters, thereby eliminating this partly subjective procedure. (USGS)

  11. Tree Growth Response to Drought Along a Depth to Groundwater Gradient in Northern Wisconsin

    Science.gov (United States)

    Ciruzzi, D. M.; Loheide, S. P., II

    2017-12-01

    Understanding complex spatial and temporal patterns of drought-induced forest stress requires knowledge of the physiological drivers and ecosystem attributes that lead to or inhibit tree mortality. Prevailing meteorological conditions leading to drought may have lesser effect on vegetation that has evolved to avoid drought by accessing deeper soil moisture reserves or shallow groundwater to meet evapotranspiration demand. This is especially true in arid and semi-arid regions, yet groundwater use by trees is rarely explored in temperate systems and the extent to which groundwater use reduces drought vulnerability in these climates and regions is unknown. We explored responses of radial growth in temperate tress to wet and dry years across a depth to groundwater gradient from 1 to 9 meters in sandy forests in northern Wisconsin. The spatial patterns of tree growth in this watershed show areas where tree growth is influenced by depth to groundwater. Preliminary results showed trees in areas of shallower groundwater with low variability in tree growth and indicated that tree growth remains consistent during both wet and dry years. Conversely, trees in areas of deeper groundwater showed higher variability in tree growth during wet and dry years. We hypothesize that even in this humid region, the sandy soils do not retain sufficient moisture leading to potentially frequent water stress in trees and reductions in productivity. However, where and when accessible, we suspect trees use shallow groundwater to sustain evapotranspiration and maintain consistent growth during dry periods.

  12. Transpiration of Eucalyptus woodlands across a natural gradient of depth-to-groundwater.

    Science.gov (United States)

    Zolfaghar, Sepideh; Villalobos-Vega, Randol; Zeppel, Melanie; Cleverly, James; Rumman, Rizwana; Hingee, Matthew; Boulain, Nicolas; Li, Zheng; Eamus, Derek

    2017-07-01

    Water resources and their management present social, economic and environmental challenges, with demand for human consumptive, industrial and environmental uses increasing globally. However, environmental water requirements, that is, the allocation of water to the maintenance of ecosystem health, are often neglected or poorly quantified. Further, transpiration by trees is commonly a major determinant of the hydrological balance of woodlands but recognition of the role of groundwater in hydrological balances of woodlands remains inadequate, particularly in mesic climates. In this study, we measured rates of tree water-use and sapwood 13C isotopic ratio in a mesic, temperate Eucalypt woodland along a naturally occurring gradient of depth-to-groundwater (DGW), to examine daily, seasonal and annual patterns of transpiration. We found that: (i) the maximum rate of stand transpiration was observed at the second shallowest site (4.3 m) rather than the shallowest (2.4 m); (ii) as DGW increased from 4.3 to 37.5 m, stand transpiration declined; (iii) the smallest rate of stand transpiration was observed at the deepest (37.5 m) site; (iv) intrinsic water-use efficiency was smallest at the two intermediate DGW sites as reflected in the Δ13C of the most recently formed sapwood and largest at the deepest and shallowest DGW sites, reflecting the imposition of flooding at the shallowest site and the inaccessibility of groundwater at the deepest site; and (v) there was no evidence of convergence in rates of water-use for co-occurring species at any site. We conclude that even in mesic environments groundwater can be utilized by trees. We further conclude that these forests are facultatively groundwater-dependent when groundwater depth is transpiration is likely to increase significantly at the three shallowest DGW sites. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  13. Representing Matrix Cracks Through Decomposition of the Deformation Gradient Tensor in Continuum Damage Mechanics Methods

    Science.gov (United States)

    Leone, Frank A., Jr.

    2015-01-01

    A method is presented to represent the large-deformation kinematics of intraply matrix cracks and delaminations in continuum damage mechanics (CDM) constitutive material models. The method involves the additive decomposition of the deformation gradient tensor into 'crack' and 'bulk material' components. The response of the intact bulk material is represented by a reduced deformation gradient tensor, and the opening of an embedded cohesive interface is represented by a normalized cohesive displacement-jump vector. The rotation of the embedded interface is tracked as the material deforms and as the crack opens. The distribution of the total local deformation between the bulk material and the cohesive interface components is determined by minimizing the difference between the cohesive stress and the bulk material stress projected onto the cohesive interface. The improvements to the accuracy of CDM models that incorporate the presented method over existing approaches are demonstrated for a single element subjected to simple shear deformation and for a finite element model of a unidirectional open-hole tension specimen. The material model is implemented as a VUMAT user subroutine for the Abaqus/Explicit finite element software. The presented deformation gradient decomposition method reduces the artificial load transfer across matrix cracks subjected to large shearing deformations, and avoids the spurious secondary failure modes that often occur in analyses based on conventional progressive damage models.

  14. Calibration of groundwater vulnerability mapping using the generalized reduced gradient method.

    Science.gov (United States)

    Elçi, Alper

    2017-12-01

    Groundwater vulnerability assessment studies are essential in water resources management. Overlay-and-index methods such as DRASTIC are widely used for mapping of groundwater vulnerability, however, these methods mainly suffer from a subjective selection of model parameters. The objective of this study is to introduce a calibration procedure that results in a more accurate assessment of groundwater vulnerability. The improvement of the assessment is formulated as a parameter optimization problem using an objective function that is based on the correlation between actual groundwater contamination and vulnerability index values. The non-linear optimization problem is solved with the generalized-reduced-gradient (GRG) method, which is numerical algorithm based optimization method. To demonstrate the applicability of the procedure, a vulnerability map for the Tahtali stream basin is calibrated using nitrate concentration data. The calibration procedure is easy to implement and aims the maximization of correlation between observed pollutant concentrations and groundwater vulnerability index values. The influence of each vulnerability parameter in the calculation of the vulnerability index is assessed by performing a single-parameter sensitivity analysis. Results of the sensitivity analysis show that all factors are effective on the final vulnerability index. Calibration of the vulnerability map improves the correlation between index values and measured nitrate concentrations by 19%. The regression coefficient increases from 0.280 to 0.485. It is evident that the spatial distribution and the proportions of vulnerability class areas are significantly altered with the calibration process. Although the applicability of the calibration method is demonstrated on the DRASTIC model, the applicability of the approach is not specific to a certain model and can also be easily applied to other overlay-and-index methods. Copyright © 2017 Elsevier B.V. All rights reserved.

  15. In situ measurement of methane oxidation in groundwater by using natural-gradient tracer tests

    International Nuclear Information System (INIS)

    Smith, R.L.; Howes, B.L.; Garabedian, S.P.

    1991-01-01

    Methane oxidation was measured in an unconfined sand and gravel aquifer (Cape Cod, Mass.) by using in situ natural-gradient tracer tests at both a pristine, oxygenated site and an anoxic, sewage-contaminated site. The tracer sites were equipped with multilevel sampling devices to create target grids of sampling points; the injectate was prepared with groundwater from the tracer site to maintain the same geochemical conditions. Methane oxidation was calculated from breakthrough curves of methane relative to halide and inert gas (hexafluoroethane) tracers and was confirmed by the appearance of 13 C-enriched carbon dioxide in experiments in which 13 C-enriched methane was used as the tracer. A V max for methane oxidation could be calculated when the methane concentration was sufficiently high to result in zero-order kinetics throughout the entire transport interval. Methane breakthrough curves could be simulated by modifying a one-dimensional advection-dispersion transport model to include a Michaelis-Menten-based consumption term for methane oxidation. The K m values for methane oxidation that gave the best match for the breakthrough curve peaks were 6.0 and 9.0 μM for the uncontaminated and contaminated sites, respectively. Natural-gradient tracer tests are a promising approach for assessing microbial processes and for testing in situ bioremediation potential in groundwater systems

  16. Investigating local variation in groundwater recharge along a topographic gradient, Walnut Creek, Iowa, USA

    Science.gov (United States)

    Schilling, K.E.

    2009-01-01

    Groundwater recharge is an important component to hydrologic studies but is known to vary considerably across the landscape. The purpose of this study was to examine 4 years of water-level behavior in a transect of four water-table wells installed at Walnut Creek, Iowa, USA to evaluate how groundwater recharge varied along a topographic gradient. The amount of daily water-table rise (WTR) in the wells was summed at monthly and annual scales and estimates of specific yield (Sy) were used to convert the WTR to recharge. At the floodplain site, Sy was estimated from the ratio of WTR to total rainfall and in the uplands was based on the ratio of baseflow to WTR. In the floodplain, where the water table is shallow, recharge occurred throughout the year whenever precipitation occurred. In upland areas where the water table was deeper, WTR occurred in a stepped fashion and varied by season. Results indicated that the greatest amount of water-table rise over the 4-year period was observed in the floodplain (379 mm), followed by the upland (211 mm) and sideslopes (122 mm). Incorporating spatial variability in recharge in a watershed will improve groundwater resource evaluation and flow and transport modeling. ?? Springer-Verlag 2008.

  17. 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)

  18. Solving groundwater flow problems by conjugate-gradient methods and the strongly implicit procedure

    Science.gov (United States)

    Hill, Mary C.

    1990-01-01

    The performance of the preconditioned conjugate-gradient method with three preconditioners is compared with the strongly implicit procedure (SIP) using a scalar computer. The preconditioners considered are the incomplete Cholesky (ICCG) and the modified incomplete Cholesky (MICCG), which require the same computer storage as SIP as programmed for a problem with a symmetric matrix, and a polynomial preconditioner (POLCG), which requires less computer storage than SIP. Although POLCG is usually used on vector computers, it is included here because of its small storage requirements. In this paper, published comparisons of the solvers are evaluated, all four solvers are compared for the first time, and new test cases are presented to provide a more complete basis by which the solvers can be judged for typical groundwater flow problems. Based on nine test cases, the following conclusions are reached: (1) SIP is actually as efficient as ICCG for some of the published, linear, two-dimensional test cases that were reportedly solved much more efficiently by ICCG; (2) SIP is more efficient than other published comparisons would indicate when common convergence criteria are used; and (3) for problems that are three-dimensional, nonlinear, or both, and for which common convergence criteria are used, SIP is often more efficient than ICCG, and is sometimes more efficient than MICCG.

  19. Fire activity and severity in the western US vary along proxy gradients representing fuel amount and fuel moisture.

    Directory of Open Access Journals (Sweden)

    Sean A Parks

    Full Text Available Numerous theoretical and empirical studies have shown that wildfire activity (e.g., area burned at regional to global scales may be limited at the extremes of environmental gradients such as productivity or moisture. Fire activity, however, represents only one component of the fire regime, and no studies to date have characterized fire severity along such gradients. Given the importance of fire severity in dictating ecological response to fire, this is a considerable knowledge gap. For the western US, we quantify relationships between climate and the fire regime by empirically describing both fire activity and severity along two climatic water balance gradients, actual evapotranspiration (AET and water deficit (WD, that can be considered proxies for fuel amount and fuel moisture, respectively. We also concurrently summarize fire activity and severity among ecoregions, providing an empirically based description of the geographic distribution of fire regimes. Our results show that fire activity in the western US increases with fuel amount (represented by AET but has a unimodal (i.e., humped relationship with fuel moisture (represented by WD; fire severity increases with fuel amount and fuel moisture. The explicit links between fire regime components and physical environmental gradients suggest that multivariable statistical models can be generated to produce an empirically based fire regime map for the western US. Such models will potentially enable researchers to anticipate climate-mediated changes in fire recurrence and its impacts based on gridded spatial data representing future climate scenarios.

  20. PRECONDITIONED CONJUGATE-GRADIENT 2 (PCG2), a computer program for solving ground-water flow equations

    Science.gov (United States)

    Hill, Mary C.

    1990-01-01

    This report documents PCG2 : a numerical code to be used with the U.S. Geological Survey modular three-dimensional, finite-difference, ground-water flow model . PCG2 uses the preconditioned conjugate-gradient method to solve the equations produced by the model for hydraulic head. Linear or nonlinear flow conditions may be simulated. PCG2 includes two reconditioning options : modified incomplete Cholesky preconditioning, which is efficient on scalar computers; and polynomial preconditioning, which requires less computer storage and, with modifications that depend on the computer used, is most efficient on vector computers . Convergence of the solver is determined using both head-change and residual criteria. Nonlinear problems are solved using Picard iterations. This documentation provides a description of the preconditioned conjugate gradient method and the two preconditioners, detailed instructions for linking PCG2 to the modular model, sample data inputs, a brief description of PCG2, and a FORTRAN listing.

  1. The groundwater circulation in the Finnsjoe area - the impact of density gradients. Part A, B, C

    International Nuclear Information System (INIS)

    Ahlbom, K.; Svensson, U.

    1991-11-01

    Saline groundwater is found in many boreholes at the Finnsjoen site. The occurrences and depths to the saline water vary however greatly between different boreholes. This report presents a conceptual model which can explain most of these differences. The model is based on several assumptions. The background and relevance for using these assumptions are discussed and estimated depths to the interface between non-saline and saline groundwater, based on the conceptual model, are presented. (au)

  2. Arsenic and metallic trace elements cycling in the surface water-groundwater-soil continuum down-gradient from a reclaimed mine area: Isotopic imprints

    Science.gov (United States)

    Khaska, Mahmoud; Le Gal La Salle, Corinne; Sassine, Lara; Cary, Lise; Bruguier, Olivier; Verdoux, Patrick

    2018-03-01

    One decade after closure of the Salsigne mine (SW France), As contamination persisted in surface water, groundwater and soil near and down-gradient from the reclaimed ore processing site (OPS). We assess the fate of As and other associated chalcophilic MTEs, and their transport in the surface-water/groundwater/soil continuum down-gradient from the reclaimed OPS, using Sr-isotopic fingerprinting. The Sr-isotope ratio was used as a tracer of transfer processes in this hydro-geosystem and was combined to sequential extraction of soil samples to evaluate the impact of contaminated soil on the underlying phreatic groundwater. The contrast in Sr isotope compositions of the different soil fractions reflects several Sr sources in the soil. In the complex hydro-geosystem around the OPS, the transport of As and MTEs is affected by a succession of factors, such as (1) Existence of a reducing zone in the aquifer below the reclaimed OPS, where groundwater shows relatively high As and MTEs contents, (2) Groundwater discharge into the stream near the reclaimed OPS causing an increase in As and MTE concentrations in surface water; (3) Partial co-precipitation of As with Fe-oxyhydroxides, contributing to some attenuation of As contents in surface water; (4) Infiltration of contaminated stream water into the unconfined aquifer down-gradient from the reclaimed OPS; (5) Accumulation of As and MTEs in soil irrigated with contaminated stream- and groundwater; (6) Release of As and MTEs from labile soil fractions to underlying the groundwater.

  3. Hydrogen for representing groundwater quality and contamination; Hidrogramas para la representacion de la calidad t contaminacion de las aguas subterraneas

    Energy Technology Data Exchange (ETDEWEB)

    Queralt, R. [Dept. Medi Ambient, Generalitat de Catalunya (Spain)

    2000-07-01

    A new groundwater hydrogram called Roda is defined. It represents the quality and contamination of the water in the form of a wheel, or clock, in which the circumference is equivalent to the legal or defined concentration limit for each of the radii corresponding to the 12 parameters involved: chlorides, sulphates, bicarbonates, nitrates, manganese, TOC, iron, potassium, magnesium, calcium, sodium and conductivity. Its practical application to the groundwater in various Catalan aquifers is reported. This involved a trial with a graphic representation hydrogram that complements already existing indices such as the ISQA for physicochemical quality, the BMWPC for biological quality and the star system for inshore seawater. It is hoped to devise a simpler representation system than RODA in the form of an index or equivalent. (Author) 10 refs.

  4. Screening tool to evaluate the vulnerability of down-gradient receptors to groundwater contaminants from uncapped landfills

    Energy Technology Data Exchange (ETDEWEB)

    Baker, Ronald J.; Reilly, Timothy J. [U.S. Geological Survey, 3450 Princeton Pike, Suite 110, Lawrenceville, NJ 08648 (United States); Lopez, Anthony [Bayer-Risse Engineering, Inc., 78 Route 173 West, Suite 6, Hampton, NJ 08827 (United States); Romanok, Kristin [U.S. Geological Survey, 3450 Princeton Pike, Suite 110, Lawrenceville, NJ 08648 (United States); Wengrowski, Edward W. [New Jersey Pinelands Commission, 15 Springfield Road, New Lisbon, NJ 08064 (United States)

    2015-09-15

    Highlights: • A spreadsheet-based risk screening tool for groundwater affected by landfills is presented. • Domenico solute transport equations are used to estimate downgradient contaminant concentrations. • Landfills are categorized as presenting high, moderate or low risks. • Analysis of parameter sensitivity and examples of the method’s application are given. • The method has value to regulators and those considering redeveloping closed landfills. - Abstract: A screening tool for quantifying levels of concern for contaminants detected in monitoring wells on or near landfills to down-gradient receptors (streams, wetlands and residential lots) was developed and evaluated. The tool uses Quick Domenico Multi-scenario (QDM), a spreadsheet implementation of Domenico-based solute transport, to estimate concentrations of contaminants reaching receptors under steady-state conditions from a constant-strength source. Unlike most other available Domenico-based model applications, QDM calculates the time for down-gradient contaminant concentrations to approach steady state and appropriate dispersivity values, and allows for up to fifty simulations on a single spreadsheet. Sensitivity of QDM solutions to critical model parameters was quantified. The screening tool uses QDM results to categorize landfills as having high, moderate and low levels of concern, based on contaminant concentrations reaching receptors relative to regulatory concentrations. The application of this tool was demonstrated by assessing levels of concern (as defined by the New Jersey Pinelands Commission) for thirty closed, uncapped landfills in the New Jersey Pinelands National Reserve, using historic water-quality data from monitoring wells on and near landfills and hydraulic parameters from regional flow models. Twelve of these landfills are categorized as having high levels of concern, indicating a need for further assessment. This tool is not a replacement for conventional numerically

  5. Analysis of the geochemical gradient created by surface-groundwater interactions within riverbanks of the East River in Crested Butte, Colorado

    Science.gov (United States)

    Lunzer, J.; Williams, K. H.; Malenda, H. F.; Nararne-Sitchler, A.

    2016-12-01

    An improved understanding of the geochemical gradient created by the mixing of surface and groundwater of a river system will have considerable impact on our understanding of microorganisms, organic cycling and biogeochemical processes within these zones. In this study, the geochemical gradient in the hyporheic zone is described using a variety of geochemical properties. A system of shallow groundwater wells were installed in a series of transects along a stream bank. Each transect consists of several wells that progress away from the river bank in a perpendicular fashion. From these wells, temperature, conductivity and pH of water samples were obtained via hand pumping or bailing. These data show a clear geochemical gradient that displays a distinct zone in the subsurface where the geochemical conditions change from surface water dominated to groundwater dominated. For this study, the East River near Crested Butte, Colorado has been selected as the river of interest due the river being a relatively undisturbed floodplain. Additionally, the specific section chosen on the East River displays relatively high sinuosity meaning that these meandering sections will produce hyporheic zones that are more laterally expansive than what would be expected on a river of lower sinuosity. This increase in lateral extension of the hyporheic zone will make depicting the subtle changes in the geochemical gradient much easier than that of a river system in which the hyporheic zone is not as laterally extensive. Data has been and will be continued to be collected at different river discharges to evaluate the geochemical gradient at differing rates. Overall, this characterization of the geochemical gradient along stream banks will produce results that will aid in the further use of geochemical methods to classify and understand hyporheic exchange zones and the potential expansion of these techniques to river systems of differing geologic and geographic conditions.

  6. Dietary flexibility in three representative waterbirds across salinity and depth gradients in salt ponds of San Francisco Bay

    Science.gov (United States)

    Takekawa, John Y.; Miles, A.K.; Tsao-Melcer, D. C.; Schoellhamer, D.H.; Fregien, S.; Athearn, N.D.

    2009-01-01

    Salt evaporation ponds have existed in San Francisco Bay, California, for more than a century. In the past decade, most of the salt ponds have been retired from production and purchased for resource conservation with a focus on tidal marsh restoration. However, large numbers of waterbirds are found in salt ponds, especially during migration and wintering periods. The value of these hypersaline wetlands for waterbirds is not well understood, including how different avian foraging guilds use invertebrate prey resources at different salinities and depths. The aim of this study was to investigate the dietary flexibility of waterbirds by examining the population number and diet of three feeding guilds across a salinity and depth gradient in former salt ponds of the Napa-Sonoma Marshes. Although total invertebrate biomass and species richness were greater in low than high salinity salt ponds, waterbirds fed in ponds that ranged from low (20 g l-1) to very high salinities (250 g l -1). American avocets (surface sweeper) foraged in shallow areas at pond edges and consumed a wide range of prey types (8) including seeds at low salinity, but preferred brine flies at mid salinity (40-80 g l-1). Western sandpipers (prober) focused on exposed edges and shoal habitats and consumed only a few prey types (2-4) at both low and mid salinities. Suitable depths for foraging were greatest for ruddy ducks (diving benthivore) that consumed a wide variety of invertebrate taxa (5) at low salinity, but focused on fewer prey (3) at mid salinity. We found few brine shrimp, common in higher salinity waters, in the digestive tracts of any of these species. Dietary flexibility allows different guilds to use ponds across a range of salinities, but their foraging extent is limited by available water depths. ?? 2009 USGS, US Government.

  7. Functional gene array-based analysis of microbial community structure in groundwaters with a gradient of contaminant levels

    Energy Technology Data Exchange (ETDEWEB)

    Waldron, P.J.; Wu, L.; Van Nostrand, J.D.; Schadt, C.W.; Watson, D.B.; Jardine, P.M.; Palumbo, A.V.; Hazen, T.C.; Zhou, J.

    2009-06-15

    To understand how contaminants affect microbial community diversity, heterogeneity, and functional structure, six groundwater monitoring wells from the Field Research Center of the U.S. Department of Energy Environmental Remediation Science Program (ERSP; Oak Ridge, TN), with a wide range of pH, nitrate, and heavy metal contamination were investigated. DNA from the groundwater community was analyzed with a functional gene array containing 2006 probes to detect genes involved in metal resistance, sulfate reduction, organic contaminant degradation, and carbon and nitrogen cycling. Microbial diversity decreased in relation to the contamination levels of the wells. Highly contaminated wells had lower gene diversity but greater signal intensity than the pristine well. The microbial composition was heterogeneous, with 17-70% overlap between different wells. Metal-resistant and metal-reducing microorganisms were detected in both contaminated and pristine wells, suggesting the potential for successful bioremediation of metal-contaminated groundwaters. In addition, results of Mantel tests and canonical correspondence analysis indicate that nitrate, sulfate, pH, uranium, and technetium have a significant (p < 0.05) effect on microbial community structure. This study provides an overall picture of microbial community structure in contaminated environments with functional gene arrays by showing that diversity and heterogeneity can vary greatly in relation to contamination.

  8. Surface complexation modeling of groundwater arsenic mobility: Results of a forced gradient experiment in a Red River flood plain aquifer, Vietnam

    DEFF Research Database (Denmark)

    Jessen, Søren; Postma, Dieke; Larsen, Flemming

    2012-01-01

    , suggesting a comparable As(III) affinity of Holocene and Pleistocene aquifer sediments. A forced gradient field experiment was conducted in a bank aquifer adjacent to a tributary channel to the Red River, and the passage in the aquifer of mixed groundwater containing up to 74% channel water was observed......Three surface complexation models (SCMs) developed for, respectively, ferrihydrite, goethite and sorption data for a Pleistocene oxidized aquifer sediment from Bangladesh were used to explore the effect of multicomponent adsorption processes on As mobility in a reduced Holocene floodplain aquifer......(III) while PO43− and Fe(II) form the predominant surface species. The SCM for Pleistocene aquifer sediment resembles most the goethite SCM but shows more Si sorption. Compiled As(III) adsorption data for Holocene sediment was also well described by the SCM determined for Pleistocene aquifer sediment...

  9. Groundwater movements around a repository

    International Nuclear Information System (INIS)

    Burgess, A.

    1977-10-01

    Based on regional models of groundwater flow, the regional hydraulic gradient at depth is equal to the regional topographic gradient. As a result, the equipotentials are near vertical. The permeability distribution with depth influences the groundwater flow patterns. A zone of sluggish flows, the quiescent zone is developed when the permeability decreases with depth. This feature is accentuated when horizontal anisotropy, with the horizontal permeability higher then the vertical permeability, is included. The presence of an inactive zone will be a prerequesite for a satisfactory repository site. The effect of an inclined discontinuity representing a singular geological feature such as a fault plane or shear zone has been modelled. The quiescent zone does not appear to be unduly disturbed by such a feature. However, meaningful quantitative predictions related to the flows in a typical singular feature cannot be made without more specific data on their hydraulic properties. Two dimensional analysis has been made for a site specific section of a candidate repository site at Forsmark, Sweden. The lateral extent of the model was defined by major tectonic features, assumed vertical. Potential gradients and pore velocities have been computed for a range of boundary conditions and assumed material properties. The potential gradients for the model with anisotropic permeability approach the average potential gradient between the boundaries. The result of this study of the initial groundwater conditions will be used as input data for the analyses of the thermomechanical perturbations of the groundwater regime. In the long term, the groundwater flow will return to the initial conditions. The residual effects of the repository on the flow will be discussed in part 2 of this report. (author)

  10. Aftershocks, groundwater changes and postseismic ground displacements related to pore pressure gradients: Insights from the 2012 Emilia-Romagna earthquake

    Science.gov (United States)

    Albano, Matteo; Barba, Salvatore; Solaro, Giuseppe; Pepe, Antonio; Bignami, Christian; Moro, Marco; Saroli, Michele; Stramondo, Salvatore

    2017-07-01

    During the 2012 Emilia-Romagna (Italy) seismic sequence, several time-dependent phenomena occurred, such as changes in the groundwater regime and chemistry, liquefaction, and postseismic ground displacements. Because time-dependent phenomena require time-dependent physical mechanisms, we interpreted such events as the result of the poroelastic response of the crust after the main shock. In our study, we performed a two-dimensional poroelastic numerical analysis calibrated with Cosmo-SkyMed interferometric data and measured piezometric levels in water wells. The simulation results are consistent with the observed postseismic ground displacement and water level changes. The simulations show that crustal volumetric changes induced by poroelastic relaxation and the afterslip along the main shock fault are both required to reproduce the amplitude (approximately 4 cm) and temporal evolution of the observed postseismic uplift. Poroelastic relaxation also affects the aftershock distribution. In fact, the aftershocks are correlated with the postseismic Coulomb stress evolution. In particular, a considerably higher fraction of aftershocks occurs when the evolving poroelastic Coulomb stress is positive. These findings highlight the need to perform calculations that adequately consider the time-dependent poroelastic effect when modeling postseismic scenarios, especially for forecasting the temporal and spatial evolution of stresses after a large earthquake. Failing to do so results in an overestimation of the afterslip and an inaccurate definition of stress and strain in the postseismic phase.

  11. Extent and Durability of Contamination of Groundwater and Water Works With The Pesticide Metabolite Bam (2,6 -dichlorbenzamide) Evaluated For Representative Aquifers In Denmark

    Science.gov (United States)

    Jørgensen, Peter R.; Clausen, Liselotte; Larsen, Flemming

    The pesticide metabolite BAM (2,6-dichlorbenzamide) is the most frequently found pesticide contaminant in Danish groundwater. In 1999 BAM was found in 26% of Danish water supply wells and the drinking water standard (0.1 µg/L) was exceeded in 11% of the wells. BAM is a metabolite from the active ingredient dichlobenil (DCB), which was used for non-agricultural total weed protection during 1966 ­ 1997. By using the numerical codes FRAC3Dvs and MODFLOW/MT3D it is the aim of the study to evaluate the extent and durability of the BAM pollution in Danish groundwater and to recommend planning strategies to avoid or minimize BAM in future water supply. The modeling was based on the total amount sold of the DCB (29.000 ton/year) combined with data for sorption and degradation of the DCB and BAM measured from comprehensive laboratory experiments with soil material representing root zone and main aquifer soil types in Denmark. As a main result the laboratory experiments revealed that BAM was only very slowly degraded in the root zone, while no degradation was observed in the sub-soil environments. Combining these model in-put data with representative data for the main aquifer types and overriding fractured clay aquitards, the modeling indicates that more than 99% of infiltrated dichlobenile has been transformed to its metabolite BAM (approximately 500 tons in total), and that currently (year 2001) approximately 100% of this compound appears widely in the groundwater and/or in the above aquitards. The modeling shows that the BAM pollution will appear in the groundwater with a high frequency in extensive parts of Denmark during the following 20 years to more than 100 years. The highest current BAM concentrations, but however also the shortest durability of the BAM pollution, will occur in contaminated aquifers, which are not covered with clay layers. Short durability in such areas is furthermore dependent on the lack of further up-stream BAM sources. The modeling moreover

  12. Groundwater recharge: Accurately representing evapotranspiration

    CSIR Research Space (South Africa)

    Bugan, Richard DH

    2011-09-01

    Full Text Available of solutes in unsaturated, partially saturated and fully saturated porous media (Simunek et al., 1999). It uses Richards' equation for variably-saturated water flow and the convection-dispersion equations for heat and solute transport, based on Fick?s Law... be of irregular shape and having non-uniform soil with a prescribed degree of anisotropy. Water flow can occur in the vertical plane, horizontal plane or radially on both sides of a vertical axis of symmetry. The boundaries of the system can be set at constant...

  13. A Study on the Surface and Subsurface Water Interaction Based on the Groundwater Recession Curve

    Science.gov (United States)

    Wang, S. T.; Chen, Y. W.; Chang, L. C.; Chiang, C. J.; Wang, Y. S.

    2017-12-01

    The interaction of surface to subsurface water is an important issue for groundwater resources assessment and management. The influences of surface water to groundwater are mainly through the rainfall recharge, river recharge and discharge and other boundary sources. During a drought period, the interaction of river and groundwater may be one of the main sources of groundwater level recession. Therefore, this study explores the interaction of surface water to groundwater via the groundwater recession. During drought periods, the pumping and river interaction together are the main mechanisms causing the recession of groundwater level. In principle, larger gradient of the recession curve indicates more groundwater discharge and it is an important characteristic of the groundwater system. In this study, to avoid time-consuming manual analysis, the Python programming language is used to develop a statistical analysis model for exploring the groundwater recession information. First, the slopes of the groundwater level hydrograph at every time step were computed for each well. Then, for each well, the represented slope to each groundwater level was defined as the slope with 90% exceedance probability. The relationship between the recession slope and the groundwater level can then be obtained. The developed model is applied to Choushui River Alluvial Fan. In most wells, the results show strong positive correlations between the groundwater levels and the absolute values of the recession slopes.

  14. Surface complexation modeling of groundwater arsenic mobility: Results of a forced gradient experiment in a Red River flood plain aquifer, Vietnam

    Science.gov (United States)

    Jessen, Søren; Postma, Dieke; Larsen, Flemming; Nhan, Pham Quy; Hoa, Le Quynh; Trang, Pham Thi Kim; Long, Tran Vu; Viet, Pham Hung; Jakobsen, Rasmus

    2012-12-01

    Three surface complexation models (SCMs) developed for, respectively, ferrihydrite, goethite and sorption data for a Pleistocene oxidized aquifer sediment from Bangladesh were used to explore the effect of multicomponent adsorption processes on As mobility in a reduced Holocene floodplain aquifer along the Red River, Vietnam. The SCMs for ferrihydrite and goethite yielded very different results. The ferrihydrite SCM favors As(III) over As(V) and has carbonate and silica species as the main competitors for surface sites. In contrast, the goethite SCM has a greater affinity for As(V) over As(III) while PO43- and Fe(II) form the predominant surface species. The SCM for Pleistocene aquifer sediment resembles most the goethite SCM but shows more Si sorption. Compiled As(III) adsorption data for Holocene sediment was also well described by the SCM determined for Pleistocene aquifer sediment, suggesting a comparable As(III) affinity of Holocene and Pleistocene aquifer sediments. A forced gradient field experiment was conducted in a bank aquifer adjacent to a tributary channel to the Red River, and the passage in the aquifer of mixed groundwater containing up to 74% channel water was observed. The concentrations of As (SCM correctly predicts desorption for As(III) but for Si and PO43- it predicts an increased adsorption instead of desorption. The goethite SCM correctly predicts desorption of both As(III) and PO43- but failed in the prediction of Si desorption. These results indicate that the prediction of As mobility, by using SCMs for synthetic Fe-oxides, will be strongly dependent on the model chosen. The SCM based on the Pleistocene aquifer sediment predicts the desorption of As(III), PO43- and Si quite superiorly, as compared to the SCMs for ferrihydrite and goethite, even though Si desorption is still somewhat under-predicted. The observation that a SCM calibrated on a different sediment can predict our field results so well suggests that sediment based SCMs may be a

  15. Application of optimization modeling to groundwater remediation at US Department of Energy facilities

    International Nuclear Information System (INIS)

    Bakr, A.A.; Dal Santo, D.J.; Smalley, R.C.; Phillips, E.C.

    1988-01-01

    This paper outlines and explores the fundamentals of the current strategies for groundwater hydraulic and quality management modeling and presents a scheme for the application of such strategies to DOE facilities. The discussion focuses on the DOE-Savannah River Operations (DOE-SR) facility. Remediation of contaminated groundwater at active and abandoned waste disposal sites has become a major element of environmental programs. Traditional groundwater remediation programs (e.g., pumping and treatment) may not represent optimal water quality management strategies at sites to be remediated. Complex, interrelated environmental (geologic/geohydrologic), institutional, engineering, and economic conditions at a site may require a more comprehensive management strategy. Groundwater management models based on the principles of operations research have been developed and used to determine optimal management strategies for water resources needs and for hypothetical remediation programs. Strategies for groundwater remediation programs have ranged from the simple removal of groundwater to complex, hydraulic gradient control programs involving groundwater removal, treatment, and recharge

  16. 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...

  17. Geochemical Investigations of Groundwater Stability

    International Nuclear Information System (INIS)

    Bath, Adrian

    2006-05-01

    palaeohydrogeological conditions. It is likely that inland areas have had longer durations of post-glacial fresh water infiltration than coastal areas, possibly causing greater degrees of dilution and dispersion of preexisting groundwaters and thus overprinting their hydrochemical and isotopic 'fingerprints'. Lower post-glacial hydraulic gradients relative to inland sites may account for the occurrence of more relict cold-climate water at coastal sites. Some general observations are based on rather thin evidence and therefore speculative. Firstly, it seems that glacial melt water penetrated many hundreds of metres and in some places to at least 1,000 m depth. However the low remaining proportions of melt water and of much older saline Shield water suggest that melt water flux did not fully displace pre-existing groundwaters at these depths. Secondly, where there has been post-glacial infiltration of palaeo-Baltic sea water, the density stratification or compartmentalisation effect coupled with low hydraulic gradient has reduced rates of subsequent fresh water circulation after shoreline recession. There are many uncertainties in interpreting these geochemical indicators in terms of the penetration depths of glacial melt waters and the degree to which they replace preexisting groundwaters, of other aspects of groundwater stability, and of comparisons between inland and coastal groundwater systems. Uncertainties derive partly from the reliability of groundwater samples as being representative of in situ conditions, and partly from the non-uniqueness of interpretative models. Future investigations using these approaches need to improve sampling, to make conjunctive use of geochemical and isotopic indicators which have varying timescales and sensitivities, and to integrate these indicators with palaeohydrogeological modelling to support the development of reliable groundwater flow and solute transport models for Performance Assessment

  18. Geochemical Investigations of Groundwater Stability

    Energy Technology Data Exchange (ETDEWEB)

    Bath, Adrian [Intellisci Ltd., Loughborough (United Kingdom)

    2006-05-15

    local palaeohydrogeological conditions. It is likely that inland areas have had longer durations of post-glacial fresh water infiltration than coastal areas, possibly causing greater degrees of dilution and dispersion of preexisting groundwaters and thus overprinting their hydrochemical and isotopic 'fingerprints'. Lower post-glacial hydraulic gradients relative to inland sites may account for the occurrence of more relict cold-climate water at coastal sites. Some general observations are based on rather thin evidence and therefore speculative. Firstly, it seems that glacial melt water penetrated many hundreds of metres and in some places to at least 1,000 m depth. However the low remaining proportions of melt water and of much older saline Shield water suggest that melt water flux did not fully displace pre-existing groundwaters at these depths. Secondly, where there has been post-glacial infiltration of palaeo-Baltic sea water, the density stratification or compartmentalisation effect coupled with low hydraulic gradient has reduced rates of subsequent fresh water circulation after shoreline recession. There are many uncertainties in interpreting these geochemical indicators in terms of the penetration depths of glacial melt waters and the degree to which they replace preexisting groundwaters, of other aspects of groundwater stability, and of comparisons between inland and coastal groundwater systems. Uncertainties derive partly from the reliability of groundwater samples as being representative of in situ conditions, and partly from the non-uniqueness of interpretative models. Future investigations using these approaches need to improve sampling, to make conjunctive use of geochemical and isotopic indicators which have varying timescales and sensitivities, and to integrate these indicators with palaeohydrogeological modelling to support the development of reliable groundwater flow and solute transport models for Performance Assessment.

  19. Administrative limits for tritium concentrations found in non-potable groundwater at nuclear power facilities

    International Nuclear Information System (INIS)

    Parker, R.; Hart, D.; WIllert, C.

    2012-01-01

    Currently, there is a regulatory limit available for tritium in drinking water, but no such limit for non-potable groundwater. Voluntary administrative limits for site groundwater may be established at nuclear power facilities to ensure minimal risk to human health and the environment, and provide guidance for investigation or other actions intended to prevent exceedances of future regulatory or guideline limits. This work presents a streamlined approach for nuclear power facilities to develop three tiers of administrative limits for tritium in groundwater so that facilities can identify abnormal/uncontrolled releases of tritium at an early stage, and take appropriate actions to investigate, control, and protect groundwater. Tier 1 represents an upper limit of background, Tier 2 represents a level between background and Tier 3, and Tier 3 represents a risk-based concentration protective of down-gradient receptors. (author)

  20. An examination of recharge mound decay and fossil gradients in arid regional sedimentary basins

    International Nuclear Information System (INIS)

    Lloyd, J.W.

    1980-01-01

    In many of the vast arid sedimentary basins of the world, groundwater gradients exist that appear to be anomalous in the context of the probable modern recharge potential. The possibility that such gradients are in fact remnant fossil conditions representing the decay of ancient recharge mounds is examined. An example of decay condition is represented using a resistor-network analogue model in which the time control is based on 14 C ages. The decay hypothesis is found to be plausible with realistic aquifer characteristics but a non-homogeneous flow is indicated from the 14 C data. (author)

  1. 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.

  2. 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.

  3. Groundwater Vulnerability Regions of Iowa

    Data.gov (United States)

    Iowa State University GIS Support and Research Facility — The regions onThis map represent areas with similar hydrogeologic characteristics thought to represent similar potentials for contamination of groundwater and/or...

  4. 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

  5. Coastal microbial mat diversity along a natural salinity gradient.

    Directory of Open Access Journals (Sweden)

    Henk Bolhuis

    Full Text Available The North Sea coast of the Dutch barrier island of Schiermonnikoog is covered by microbial mats that initiate a succession of plant communities that eventually results in the development of a densely vegetated salt marsh. The North Sea beach has a natural elevation running from the low water mark to the dunes resulting in gradients of environmental factors perpendicular to the beach. These gradients are due to the input of seawater at the low water mark and of freshwater from upwelling groundwater at the dunes and rainfall. The result is a natural and dynamic salinity gradient depending on the tide, rainfall and wind. We studied the microbial community composition in thirty three samples taken every ten meters along this natural salinity gradient by using denaturing gradient gel electrophoresis (DGGE of rRNA gene fragments. We looked at representatives from each Domain of life (Bacteria, Archaea and Eukarya and with a particular emphasis on Cyanobacteria. Analysis of the DGGE fingerprints together with pigment composition revealed three distinct microbial mat communities, a marine community dominated by diatoms as primary producers, an intermediate brackish community dominated by Cyanobacteria as primary producers and a freshwater community with Cyanobacteria and freshwater green algae.

  6. 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

  7. Geology of groundwater occurrences of the Lower Cretaceus sandstone aquifer in East Central Sinai, Egypt

    Directory of Open Access Journals (Sweden)

    Saad Younes Ghoubachi

    2017-01-01

    Full Text Available The present study focused on investigating the impact of geological setting on the groundwater occurrences of the Lower Cretaceous sandstone aquifer (Malha. The Lower Cretaceous sandstone aquifer is subdivided into 3 units according to their lithological characters for the first time in this present work. The study area is dissected by normal faults with their downthrown sides due north direction. The groundwater flows from southeast recharge area (outcrop to the northwest direction with an average hydraulic gradient of 0.0035. The hydraulic parameters of the Lower Cretaceous sandstone aquifer were determined and evaluated through 7 pumping tests carried out on productive wells. The Lower Cretaceous aquifer in the study area is characterized by moderate to high potential. The calculated groundwater volume of the Lower Cretaceous aquifer (6300 km2 in the study area attains about 300 bcm, while the estimated recharge to the same aquifer reaches about 44,500 m3/day with an annual recharge of 16 mcm/year. Expended Durov diagram plot revealed that the groundwater has been evolved from Mg-SO4 and Mg-Cl dissolution area types that eventually reached a final stage of evolution represented by a Na-Cl water type. This diagram helps also in identifying groundwater flow direction. The groundwater salinity ranges from 1082 ppm (Shaira to 1719 ppm (Nakhl, in the direction of groundwater movement towards north.

  8. Geostatistical analysis of groundwater chemistry in Japan. Evaluation of the base case groundwater data set

    Energy Technology Data Exchange (ETDEWEB)

    Salter, P.F.; Apted, M.J. [Monitor Scientific LLC, Denver, CO (United States); Sasamoto, Hiroshi; Yui, Mikazu

    1999-05-01

    information on depth and temperature reduces the number of samples to 7,140. These waters are then screened on the basis of thermal imprints effects (recorded temperature > predicted temperature from geothermal gradient and depth information). These 880 thermally altered waters are used in volcanism scenario analyses. The remaining samples are divided into two groups, groundwaters at < 200m depth and groundwaters > 200m depth. The former group is identified for use in the uplift and erosion scenario (in which the repository may approach closer to the ground surface in the far future due to these two processes). The remaining 950 samples define the deep groundwaters for a potential repository. A subset (560 samples) of the 950 deep samples based on maximum sample depth information is selected by JNC considering rock formation (excluded Quaternary unconsolidate sediments) as the Deep Repository Groundwater Dataset for the PCA/HCA. Combined PCA and HCA of the Deep Repository Groundwater Dataset substantiates three reference groundwater categories: 1) a dilute, Na-HCO3 type groundwater possibly divided into two subtypes based on pH [one with high pH ({approx}8) and one with low pH ({approx}6), 2) a higher temperature ({approx}40degC) moderate ionic strength Na-HCO3 type groundwater with pH between 7 and 9; and 3) a saline (near seawater ionic strength), high pH ({approx}8) brine. Comparison of these results with the proposed hypothetical reference groundwater samples indicates that some of the proposed reference groundwaters do not appear to closely represent any of the categories derived by PCA/HCA for the deep Japanese groundwater data sets used. There may be several reasons for this. First, the initial data set of 15,000 samples does not necessarily represent a complete, uniform coverage of groundwater have been eliminated before PCA/HCA because the samples lacked one of key major chemical variables selected for the analyses (e.g., Na{sup +}). Thus, in order to assure a broad

  9. An intelligent instrument for measuring the dynamic parameters of groundwater

    International Nuclear Information System (INIS)

    Du Guoping

    2002-01-01

    An intelligent instrument was developed for measuring direction and velocity of the groundwater, permeability coefficient, hydraulic transmitting coefficient, static level, hydraulic gradient and flow direction of each layer. The instrument can be widely applied for detecting seepage of abutment and river bank, exploitation of groundwater, conservation of water and soil, water surging in mine, survey of groundwater resource and environment protection etc

  10. Groundwater Monitoring and Engineered Geothermal Systems: The Newberry EGS Demonstration

    Science.gov (United States)

    Grasso, K.; Cladouhos, T. T.; Garrison, G.

    2013-12-01

    Engineered Geothermal Systems (EGS) represent the next generation of geothermal energy development. Stimulation of multiple zones within a single geothermal reservoir could significantly reduce the cost of geothermal energy production. Newberry Volcano in central Oregon represents an ideal location for EGS research and development. As such, the goals of the Newberry EGS Demonstration, operated by AltaRock Energy, Inc., include stimulation of a multiple-zone EGS reservoir, testing of single-well tracers and a demonstration of EGS reservoir viability through flow-back and circulation tests. A shallow, local aquifer supplied the approximately 41,630 m3 (11 million gals) of water used during stimulation of NWG 55-29, a deep geothermal well on the western flank of Newberry Volcano. Protection of the local aquifer is of primary importance to both the Newberry EGS Demonstration and the public. As part of the Demonstration, AltaRock Energy, Inc. has developed and implemented a groundwater monitoring plan to characterize the geochemistry of the local aquifer before, during and after stimulation. Background geochemical conditions were established prior to stimulation of NWG 55-29, which was completed in 2012. Nine sites were chosen for groundwater monitoring. These include the water supply well used during stimulation of NWG 55-29, three monitoring wells, three domestic water wells and two hot seeps located in the Newberry Caldera. Together, these nine monitoring sites represent up-, down- and cross-gradient locations. Groundwater samples are analyzed for 25 chemical constituents, stable isotopes, and geothermal tracers used during stimulation. In addition, water level data is collected at three monitoring sites in order to better characterize the effects of stimulation on the shallow aquifer. To date, no significant geochemical changes and no geothermal tracers have been detected in groundwater samples from these monitoring sites. The Newberry EGS Demonstration groundwater

  11. Groundwater Modelling For Recharge Estimation Using Satellite Based Evapotranspiration

    Science.gov (United States)

    Soheili, Mahmoud; (Tom) Rientjes, T. H. M.; (Christiaan) van der Tol, C.

    2017-04-01

    Groundwater movement is influenced by several factors and processes in the hydrological cycle, from which, recharge is of high relevance. Since the amount of aquifer extractable water directly relates to the recharge amount, estimation of recharge is a perquisite of groundwater resources management. Recharge is highly affected by water loss mechanisms the major of which is actual evapotranspiration (ETa). It is, therefore, essential to have detailed assessment of ETa impact on groundwater recharge. The objective of this study was to evaluate how recharge was affected when satellite-based evapotranspiration was used instead of in-situ based ETa in the Salland area, the Netherlands. The Methodology for Interactive Planning for Water Management (MIPWA) model setup which includes a groundwater model for the northern part of the Netherlands was used for recharge estimation. The Surface Energy Balance Algorithm for Land (SEBAL) based actual evapotranspiration maps from Waterschap Groot Salland were also used. Comparison of SEBAL based ETa estimates with in-situ abased estimates in the Netherlands showed that these SEBAL estimates were not reliable. As such results could not serve for calibrating root zone parameters in the CAPSIM model. The annual cumulative ETa map produced by the model showed that the maximum amount of evapotranspiration occurs in mixed forest areas in the northeast and a portion of central parts. Estimates ranged from 579 mm to a minimum of 0 mm in the highest elevated areas with woody vegetation in the southeast of the region. Variations in mean seasonal hydraulic head and groundwater level for each layer showed that the hydraulic gradient follows elevation in the Salland area from southeast (maximum) to northwest (minimum) of the region which depicts the groundwater flow direction. The mean seasonal water balance in CAPSIM part was evaluated to represent recharge estimation in the first layer. The highest recharge estimated flux was for autumn

  12. Nutrients fluxes from groundwater discharge into Mangueira Lagoon (Rio Grande do Sul, Brazil); Fluxos de nutrientes associados as descargas de agua subterranea para a Lagoa Mangueira (Rio Grande do Sul, Brasil)

    Energy Technology Data Exchange (ETDEWEB)

    Andrade, Carlos F.F.; Niencheski, Luis F.H.; Attisano, Karina K.; Milani, Marcio R., E-mail: pgofcfa@furg.br [Instituto de Oceanografia, Universidade Federal do Rio Grande, Campus Carreiros, Rio Grande, RS (Brazil); Santos, Isaac R. [Department of Oceanography, Florida State University, Tallahassee, FL (United States); Milani, Idel C. [Departamento de Engenharia Hidrica, Centro de Desenvolvimento Tecnologico, Universidade Federal de Pelotas, Campus Porto, Pelotas, RS (Brazil)

    2012-07-01

    This study assesses the importance of groundwater discharge to dissolved nutrient levels in Mangueira Lagoon. A transect of an irrigation canal in the margin of Lagoon demonstrated a strong geochemical gradient due to high groundwater inputs in this area. Using {sup 222}Rn as a quantitative groundwater tracer, we observed that the flux of dissolved inorganic nitrogen (DIN), silicate and phosphate (1178 and 1977; 26190 and 35652; 167 and 188 mol d{sup -1} for winter and summer, respectively) can continually supply/sustain primary production. The irrigation canals act as an artificial underground tributary and represent a new source of nutrients to coastal lagoons. (author)

  13. Hydraulic gradients in rock aquifers

    International Nuclear Information System (INIS)

    Dahlblom, P.

    1992-05-01

    This report deals with fractured rock as a host for deposits of hazardous waste. In this context the rock, with its fractures containing moving groundwater, is called the geological barrier. The desired properties of the geological barrier are low permeability to water, low hydraulic gradients and ability to retain matter dissolved in the water. The hydraulic gradient together with the permeability and the porosity determines the migration velocity. Mathematical modelling of the migration involves calculation of the water flow and the hydrodynamic dispersion of the contaminant. The porous medium approach can be used to calculate mean flow velocities and hydrodynamic dispersion of a large number of fractures are connected, which means that a large volume have to be considered. It is assumed that the porous medium approach can be applied, and a number of idealized examples are shown. It is assumed that the groundwater table is replenished by percolation at a constant rate. One-dimensional analytical calculations show that zero hydraulic gradients may exist at relatively large distance from the coast. Two-dimensional numerical calculations show that it may be possible to find areas with low hydraulic gradients and flow velocities within blocks surrounded by areas with high hydraulic conductivity. (au)

  14. Municipal waste management and groundwater contamination processes in Córdoba Province, Argentina

    Directory of Open Access Journals (Sweden)

    Daniel Emilio Martínez

    2010-12-01

    Full Text Available In Coronel Moldes, Argentina, waste management practices consist in municipal waste being tipped directly onto an area of sand dunes at the municipal waste disposal site (MWDS. Moreover, untreated liquid waste from septic tanks and latrines from urban areas are discharged in the same place. This co-disposal waste management is very common in many regions of Argentina and its impact on the groundwater of Coronel Moldes has not been evaluated. The study area is located in the vicinity of a MWDS in a flatlands environment that is typical of Argentina. The main objective of this study was to evaluate the impacts on groundwater quality of current waste management practices in order to consider the requirement for new guidelines for sustainable groundwater management. Three groundwater monitoring wells were installed up-, across- and down-gradient of the MWDS. The principal aquifer is formed by sandy silt sediments (loess. Groundwater levels in the area of the MWDS are between 5.6 m and 7.8 m. The Vulnerability index indicates that groundwater in this area has a high vulnerability. Groundwater in the vicinity of the MWDS shows elevated electrical conductivity, high concentrations of Cl-, Na+, and HCO3- ions, COD, BOD5 and aerobic bacteria and less dissolved oxygen than the background values indicating the presence of organic matter. Municipal waste management represents a significant omission in current groundwater protection policy at Coronel Moldes. Strict supervision of solid and liquid municipal waste disposal needs to be instigated in order to ensure that the groundwater remains free of contamination and to allow a sustainable environmental management.

  15. Representing Development

    DEFF Research Database (Denmark)

    Representing Development presents the different social representations that have formed the idea of development in Western thinking over the past three centuries. Offering an acute perspective on the current state of developmental science and providing constructive insights into future pathways, ...

  16. Application of Geospatial Techniques for Groundwater Quality and Availability Assessment: A Case Study in Jaffna Peninsula, Sri Lanka

    Directory of Open Access Journals (Sweden)

    Kuddithamby Gunaalan

    2018-01-01

    Full Text Available Groundwater is one of the most important natural resources in the northern coastal belt of Sri Lanka, as there are no major water supply schemes or perennial rivers. Overexploitation, seawater intrusion and persistent pollution of this vital resource are threatening human health as well as ecosystems in the Jaffna Peninsula. Therefore, the main intent of the present paper is to apply geospatial techniques to assess the spatial variation of groundwater quality and availability for the sustainable management of groundwater in the coastal areas. The electrical conductivity (EC and depth to water (DTW of 41 wells were measured during the period from March to June 2014, which represents the dry period of the study area. Surface interpolation, gradient analysis, a local indicators of spatial autocorrelations (LISA and statistical analysis were used to assess the quality and availability of groundwater. The results revealed that the drinking and irrigation water quality in the study area were poor and further deteriorated with the progression of the dry season. Good quality and availability of groundwater were observed in the western zone compared to other zones of the study area. A negative correlation was identified between depth to water and electrical conductivity in the western zone. Hence, relatively deep wells in the western zone of the study area can be used to utilize the groundwater for drinking, domestic and agricultural purposes. The outcomes of this study can be used to formulate policy decisions for sustainable management of groundwater resources in Jaffna Peninsula.

  17. Irradiance gradients

    International Nuclear Information System (INIS)

    Ward, G.J.; Heckbert, P.S.; Technische Hogeschool Delft

    1992-04-01

    A new method for improving the accuracy of a diffuse interreflection calculation is introduced in a ray tracing context. The information from a hemispherical sampling of the luminous environment is interpreted in a new way to predict the change in irradiance as a function of position and surface orientation. The additional computation involved is modest and the benefit is substantial. An improved interpolation of irradiance resulting from the gradient calculation produces smoother, more accurate renderings. This result is achieved through better utilization of ray samples rather than additional samples or alternate sampling strategies. Thus, the technique is applicable to a variety of global illumination algorithms that use hemicubes or Monte Carlo sampling techniques

  18. Groundwater Potential

    African Journals Online (AJOL)

    big timmy

    4Department of Geology, Ekiti State University, Ado-Ekiti, Nigeria. Corresponding ... integrated for the classification of the study area into different groundwater potential zones. .... table is mainly controlled by subsurface movement of water into ...

  19. Representing dispositions

    Directory of Open Access Journals (Sweden)

    Röhl Johannes

    2011-08-01

    Full Text Available Abstract Dispositions and tendencies feature significantly in the biomedical domain and therefore in representations of knowledge of that domain. They are not only important for specific applications like an infectious disease ontology, but also as part of a general strategy for modelling knowledge about molecular interactions. But the task of representing dispositions in some formal ontological systems is fraught with several problems, which are partly due to the fact that Description Logics can only deal well with binary relations. The paper will discuss some of the results of the philosophical debate about dispositions, in order to see whether the formal relations needed to represent dispositions can be broken down to binary relations. Finally, we will discuss problems arising from the possibility of the absence of realizations, of multi-track or multi-trigger dispositions and offer suggestions on how to deal with them.

  20. Representing time

    Directory of Open Access Journals (Sweden)

    Luca Poncellini

    2010-06-01

    Full Text Available The analysis of natural phenomena applied to architectural planning and design is facing the most fascinating and elusive of the four dimensions through which man attempts to define life within the universe: time. We all know what time is, said St. Augustine, but nobody knows how to describe it. Within architectural projects and representations, time rarely appears in explicit form. This paper presents the results of a research conducted by students of NABA and of the Polytechnic of Milan with the purpose of representing time considered as a key element within architectural projects. Student investigated new approaches and methodologies to represent time using the two-dimensional support of a sheet of paper.

  1. Directional phytoscreening: contaminant gradients in trees for plume delineation.

    Science.gov (United States)

    Limmer, Matt A; Shetty, Mikhil K; Markus, Samantha; Kroeker, Ryan; Parker, Beth L; Martinez, Camilo; Burken, Joel G

    2013-08-20

    Tree sampling methods have been used in phytoscreening applications to delineate contaminated soil and groundwater, augmenting traditional investigative methods that are time-consuming, resource-intensive, invasive, and costly. In the past decade, contaminant concentrations in tree tissues have been shown to reflect the extent and intensity of subsurface contamination. This paper investigates a new phytoscreening tool: directional tree coring, a concept originating from field data that indicated azimuthal concentrations in tree trunks reflected the concentration gradients in the groundwater around the tree. To experimentally test this hypothesis, large diameter trees were subjected to subsurface contaminant concentration gradients in a greenhouse study. These trees were then analyzed for azimuthal concentration gradients in aboveground tree tissues, revealing contaminant centroids located on the side of the tree nearest the most contaminated groundwater. Tree coring at three field sites revealed sufficiently steep contaminant gradients in trees reflected nearby groundwater contaminant gradients. In practice, trees possessing steep contaminant gradients are indicators of steep subsurface contaminant gradients, providing compass-like information about the contaminant gradient, pointing investigators toward higher concentration regions of the plume.

  2. South-East Iowa Groundwater Vulnerability Regions

    Data.gov (United States)

    Iowa State University GIS Support and Research Facility — The regions on this map represent areas with similar hydro- geologic characteristics thought to represent similar potentials for contamination of groundwater and/or...

  3. North-East Iowa Groundwater Vulnerability Regions

    Data.gov (United States)

    Iowa State University GIS Support and Research Facility — The regions on this map represent areas with similar hydro-geologic characteristics thought to represent similar potentials for contamination of groundwater and/or...

  4. North-West Iowa Groundwater Vulnerability Regions

    Data.gov (United States)

    Iowa State University GIS Support and Research Facility — The regions on this map represent areas with similar hydro-geologic characteristics thought to represent similar potentials for contamination of groundwater and/or...

  5. South-West Iowa Groundwater Vulnerability Regions

    Data.gov (United States)

    Iowa State University GIS Support and Research Facility — The regions on this map represent areas with similar hydro- geologic characteristics thought to represent similar potentials for contamination of groundwater and/or...

  6. 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

  7. 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

  8. Mass transport by groundwater

    International Nuclear Information System (INIS)

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

    1991-01-01

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

  9. Three-dimensional groundwater velocity field in an unconfined aquifer under irrigation

    International Nuclear Information System (INIS)

    Zlotnik, V.

    1990-01-01

    A method for three-dimensional flow velocity calculation has been developed to evaluate unconfined aquifer sensitivity to areal agricultural contamination of groundwater. The methodology of Polubarinova-Kochina is applied to an unconfined homogeneous compressible or incompressible anisotropic aquifer. It is based on a three-dimensional groundwater flow model with a boundary condition on the moving surface. Analytical solutions are obtained for a hydraulic head under the influence of areal sources of circular and rectangular shape using integral transforms. Two-dimensional Hantush formulas result from the vertical averaging of the three-dimensional solutions, and the asymptotic behavior of solutions is analyzed. Analytical expressions for flow velocity components are obtained from the gradient of the hydraulic head field. Areal and temporal variability of specific yield in groundwater recharge areas is also taken into account. As a consequence of linearization of the boundary condition, the operation of any irrigation system with respect to groundwater is represented by superposition of the operating wells and circular and rectangular source influences. Combining the obtained solutions with Dagan or Neuman well functions, one can develop computer codes for the analytical computation of the three-dimensional groundwater hydraulic head and velocity component distributions. Methods for practical implementation are discussed. (Author) (20 refs., 4 figs.)

  10. Groundwater and surface-water interaction within the upper Smith River Watershed, Montana 2006-2010

    Science.gov (United States)

    Caldwell, Rodney R.; Eddy-Miller, Cheryl A.

    2013-01-01

    and surface-water interactions occur downstream from the confluence of the North and South Fork Smith Rivers, but are less discernible compared to the overall magnitude of the main-stem streamflow. The Smith River was perennial throughout the study. Monitoring sites along the Smith River generally displayed small head gradients between the stream and the groundwater, while one site consistently showed strongly gaining conditions. Synoptic streamflow measurements during periods of limited irrigation diversion in 2007 and 2008 consistently showed gains over the upper 41.4 river miles of the main stem Smith River where net gains ranged from 13.0 to 28.9 cubic feet per second. Continuous streamflow data indicated net groundwater discharge and small-scale tributary inflow contributions of around 25 cubic feet per second along the upper 10-mile reach of the Smith River for most of the 2010 record. A period of intense irrigation withdrawal during the last two weeks in May was followed by a period (early June 2010 to mid-July 2010) with the largest net increase (an average of 71.1 cubic feet per second) in streamflow along this reach of the Smith River. This observation is likely due to increased groundwater discharge to the Smith River resulting from irrigation return flow. By late July, the apparent effects of return flows receded, and the net increase in streamflow returned to about 25 cubic feet per second. Two-dimensional heat and solute transport VS2DH models representing selected stream cross sections were used to constrain the hydraulic properties of the Quaternary alluvium and estimate temporal water-flux values through model boundaries. Hydraulic conductivity of the Quaternary alluvium of the modeled sections ranged from 3x10-6 to 4x10-5 feet per second. The models showed reasonable approximations of the streambed and shallow aquifer environment, and the dynamic changes in water flux between the stream and the groundwater through different model boundaries.

  11. Patterns of macromycete community assemblage along an elevation gradient: options for fungal gradient and metacommunity analyse

    Science.gov (United States)

    Marko Gómez-Hernández; Guadalupe Williams-Linera; Roger Guevara; D. Jean Lodge

    2012-01-01

    Gradient analysis is rarely used in studies of fungal communities. Data on macromycetes from eight sites along an elevation gradient in central Veracruz, Mexico, were used to demonstrate methods for gradient analysis that can be applied to studies of communities of fungi. Selected sites from 100 to 3,500 m altitude represent tropical dry forest, tropical montane cloud...

  12. Construction and calibration of a groundwater-flow model to assess groundwater availability in the uppermost principal aquifer systems of the Williston Basin, United States and Canada

    Science.gov (United States)

    Davis, Kyle W.; Long, Andrew J.

    2018-05-31

    -flow gradients that were topographically controlled in outcrop areas and more generalized regional gradients where the aquifers were confined. The differences between the measured and simulated (residuals) hydraulic head values for 11,109 wells were assessed, which indicated that the steady-state model generally underestimated hydraulic head in the model area. This underestimation is indicated by a positive mean residual of 11.2 feet for all model layers. Layer 7, which represents the lower Hell Creek aquifer, is the only layer for which the steady-state model overestimated hydraulic head. Simulated groundwater-level changes for the transient model matched within plus or minus 2.5 feet of the measured values for more than 60 percent of all measurements and to within plus or minus 17.5 feet for 95 percent of all measurements; however, the transient model underestimated groundwater-level changes for all model layers. A comparison between simulated and estimated base flows for the steady-state and transient models indicated that both models overestimated base flow in streams and underestimated annual fluctuations in base flow.The estimated and simulated groundwater budgets indicate the model area received a substantial amount of recharge from precipitation and stream infiltration. The steady-state model indicated that reservoir seepage was a larger component of recharge in the Williston Basin than was previously estimated. Irrigation recharge and groundwater inflow from outside the Williston Basin accounted for a relatively small part of total groundwater recharge when compared with recharge from precipitation, stream infiltration, and reservoir seepage. Most of the estimated and simulated groundwater discharge in the Williston Basin was to streams and reservoirs. Simulated groundwater withdrawal, discharge to reservoirs, and groundwater outflow in the Williston Basin accounted for a smaller part of total groundwater discharge.The transient model was used to simulate discharge to

  13. MODIFIED ARMIJO RULE ON GRADIENT DESCENT AND CONJUGATE GRADIENT

    Directory of Open Access Journals (Sweden)

    ZURAIDAH FITRIAH

    2017-10-01

    Full Text Available Armijo rule is an inexact line search method to determine step size in some descent method to solve unconstrained local optimization. Modified Armijo was introduced to increase the numerical performance of several descent algorithms that applying this method. The basic difference of Armijo and its modified are in existence of a parameter and estimating the parameter that is updated in every iteration. This article is comparing numerical solution and time of computation of gradient descent and conjugate gradient hybrid Gilbert-Nocedal (CGHGN that applying modified Armijo rule. From program implementation in Matlab 6, it's known that gradient descent was applying modified Armijo more effectively than CGHGN from one side: iteration needed to reach some norm of the gradient  (input by the user. The amount of iteration was representing how long the step size of each algorithm in each iteration. In another side, time of computation has the same conclusion.

  14. Groundwater recharge and agricultural contamination

    Science.gov (United States)

    Böhlke, J.K.

    2002-01-01

    Agriculture has had direct and indirect effects on the rates and compositions of groundwater recharge and aquifer biogeochemistry. Direct effects include dissolution and transport of excess quantities of fertilizers and associated materials and hydrologic alterations related to irrigation and drainage. Some indirect effects include changes in water–rock reactions in soils and aquifers caused by increased concentrations of dissolved oxidants, protons, and major ions. Agricultural activities have directly or indirectly affected the concentrations of a large number of inorganic chemicals in groundwater, for example NO3–, N2, Cl, SO42–, H+, P, C, K, Mg, Ca, Sr, Ba, Ra, and As, as well as a wide variety of pesticides and other organic compounds. For reactive contaminants like NO3–, a combination of chemical, isotopic, and environmental-tracer analytical approaches might be required to resolve changing inputs from subsequent alterations as causes of concentration gradients in groundwater. Groundwater records derived from multi-component hydrostratigraphic data can be used to quantify recharge rates and residence times of water and dissolved contaminants, document past variations in recharging contaminant loads, and identify natural contaminant-remediation processes. These data indicate that many of the world's surficial aquifers contain transient records of changing agricultural contamination from the last half of the 20th century. The transient agricultural groundwater signal has important implications for long-term trends and spatial heterogeneity in discharge.

  15. Temperature distribution by the effect of groundwater flow in an aquifer thermal energy storage system model

    Science.gov (United States)

    Shim, B.

    2005-12-01

    Aquifer thermal energy storage (ATES) can be a cost-effective and renewable energy source, depending on site-specific thermohydraulic conditions. To design an effective ATES system, the understanding of thermohydraulic processes is necessary. The heat transfer phenomena of an aquifer heat storage system are simulated with the scenario of heat pump operation of pumping and waste water reinjection in a two layered confined aquifer model having the effect of groundwater movement. Temperature distribution of the aquifer model is generated, and hydraulic heads and temperature variations are monitored at both wells during simulation days. The average groundwater velocities are determined with two assumed hydraulic gradients set by boundary conditions, and the effect of groundwater flow are shown at the generated thermal distributions at three different depth slices. The generated temperature contour lines at the hydraulic gradient of 0.001 are shaped circular, and the center is moved less than 5 m to the east in 365 days. However at the hydraulic gradient of 0.01, the contour centers of the east well at each depth slice are moved near the east boundary and the movement of temperature distribution is increased at the lower aquifer. By the analysis of thermal interference data between two wells the efficiency of a heat pump operation model is validated, and the variation of heads is monitored at injection, pumping and stabilized state. The thermal efficiency of the ATES system model is represented as highly depended on groundwater flow velocity and direction. Therefore the hydrogeologic condition for the system site should be carefully surveyed.

  16. 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

  17. Towards a theory of ecotone resilience: coastal vegetation on a salinity gradient.

    Science.gov (United States)

    Jiang, Jiang; Gao, Daozhou; DeAngelis, Donald L

    2012-08-01

    Ecotones represent locations where vegetation change is likely to occur as a result of climate and other environmental changes. Using a model of an ecotone vulnerable to such future changes, we estimated the resilience of the ecotone to disturbances. The specific ecotone is that between two different vegetation types, salinity-tolerant and salinity-intolerant, along a gradient in groundwater salinity. In the case studied, each vegetation type, through soil feedback loops, promoted local soil salinity levels that favor itself in competition with the other type. Bifurcation analysis was used to study the system of equations for the two vegetation types and soil salinity. Alternative stable equilibria, one for salinity-tolerant and one for salinity intolerant vegetation, were shown to exist over a region of the groundwater salinity gradient, bounded by two bifurcation points. This region was shown to depend sensitively on parameters such as the rate of upward infiltration of salinity from groundwater into the soil due to evaporation. We showed also that increasing diffusion rates of vegetation can lead to shrinkage of the range between the two bifurcation points. Sharp ecotones are typical of salt-tolerant vegetation (mangroves) near the coastline and salt-intolerant vegetation inland, even though the underlying elevation and groundwater salinity change very gradually. A disturbance such as an input of salinity to the soil from a storm surge could upset this stable boundary, leading to a regime shift of salinity-tolerant vegetation inland. We showed, however, that, for our model as least, a simple pulse disturbance would not be sufficient; the salinity would have to be held at a high level, as a 'press', for some time. The approach used here should be generalizable to study the resilience of a variety of ecotones to disturbances. Published by Elsevier Inc.

  18. Groundwater flow analyses in Japan. 1. Case studies in Hokkaido and Northeast Japan

    International Nuclear Information System (INIS)

    Inaba, Hideo; Maekawa, Keisuke; Koide, Kaoru; Yanagizawa, Koichi

    1995-01-01

    An extensive study program has been carried out to estimate hydrogeological characteristics of deep underground in Japan. As a part of this program, groundwater flow analysis in Hokkaido and Northeast Japan were conducted. For the analyses of these area, hydrogeological models representing topography, geology, distribution of hydraulic conductivity were developed using available informations from open literature. By use of these models, steady state three-dimensional groundwater flow under a saturated/unsaturated condition was calculated by means of finite element method. The results are as follows: (1) Distribution of piezometric head corresponds with topography in the study area. (2) Piezometric head distribution is hydrostatic below E.L.-1000m in the study area. (3) Hydraulic gradient in the study area is less than 0.04 below E.L.-500m. (4) Difference of boundary conditions at the shore side of these models does not affect the results of the analyses. (author)

  19. Examining the spatial and temporal variation of groundwater inflows to a valley-to-floodplain river using 222Rn, geochemistry and river discharge: the Ovens River, southeast Australia

    Science.gov (United States)

    Yu, M. C. L.; Cartwright, I.; Braden, J. L.; de Bree, S. T.

    2013-12-01

    Radon (222Rn) and major ion geochemistry were used to define and quantify the catchment-scale groundwater-surface water interactions along the Ovens River in the southeast Murray-Darling Basin, Victoria, Australia, between September 2009 and October 2011. The Ovens River is characterized by the transition from a single channel within a mountain valley in the upper catchment to a multi-channel meandering river on flat alluvial plains in the lower catchment. Overall, the Ovens River is dominated by gaining reaches, receiving groundwater from both alluvial and basement aquifers. The distribution of gaining and losing reaches is governed by catchment morphology and lithology. In the upper catchment, rapid groundwater recharge through the permeable aquifers increases the water table. The rising water table, referred to as hydraulic loading, increases the hydraulic head gradient toward the river and hence causes high baseflow to the river during wet (high flow) periods. In the lower catchment, lower rainfall and finer-gained sediments reduce the magnitude and variability of hydraulic gradient between the aquifer and the river, producing lower but more constant groundwater inflows. The water table in the lower reaches has a shallow gradient, and small changes in river height or groundwater level can result in fluctuating gaining and losing behaviour. The middle catchment represents a transition in river-aquifer interactions from the upper to the lower catchment. High baseflow in some parts of the middle and lower catchments is caused by groundwater flowing over basement highs. Mass balance calculations based on 222Rn activities indicate that groundwater inflows are 2 to 17% of total flow with higher inflows occurring during high flow periods. In comparison to 222Rn activities, estimates of groundwater inflows from Cl concentrations are higher by up to 2000% in the upper and middle catchment but lower by 50 to 100% in the lower catchment. The high baseflow estimates using

  20. 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.

  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. 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

  3. Dose gradient curve: A new tool for evaluating dose gradient.

    Science.gov (United States)

    Sung, KiHoon; Choi, Young Eun

    2018-01-01

    Stereotactic radiotherapy, which delivers an ablative high radiation dose to a target volume for maximum local tumor control, requires a rapid dose fall-off outside the target volume to prevent extensive damage to nearby normal tissue. Currently, there is no tool to comprehensively evaluate the dose gradient near the target volume. We propose the dose gradient curve (DGC) as a new tool to evaluate the quality of a treatment plan with respect to the dose fall-off characteristics. The average distance between two isodose surfaces was represented by the dose gradient index (DGI) estimated by a simple equation using the volume and surface area of isodose levels. The surface area was calculated by mesh generation and surface triangulation. The DGC was defined as a plot of the DGI of each dose interval as a function of the dose. Two types of DGCs, differential and cumulative, were generated. The performance of the DGC was evaluated using stereotactic radiosurgery plans for virtual targets. Over the range of dose distributions, the dose gradient of each dose interval was well-characterized by the DGC in an easily understandable graph format. Significant changes in the DGC were observed reflecting the differences in planning situations and various prescription doses. The DGC is a rational method for visualizing the dose gradient as the average distance between two isodose surfaces; the shorter the distance, the steeper the dose gradient. By combining the DGC with the dose-volume histogram (DVH) in a single plot, the DGC can be utilized to evaluate not only the dose gradient but also the target coverage in routine clinical practice.

  4. Ground-Water Flow Model of the Sierra Vista Subwatershed and Sonoran Portions of the Upper San Pedro Basin, Southeastern Arizona, United States, and Northern Sonora, Mexico

    Science.gov (United States)

    Pool, D.R.; Dickinson, Jesse

    2007-01-01

    A numerical ground-water model was developed to simulate seasonal and long-term variations in ground-water flow in the Sierra Vista subwatershed, Arizona, United States, and Sonora, Mexico, portions of the Upper San Pedro Basin. This model includes the simulation of details of the groundwater flow system that were not simulated by previous models, such as ground-water flow in the sedimentary rocks that surround and underlie the alluvial basin deposits, withdrawals for dewatering purposes at the Tombstone mine, discharge to springs in the Huachuca Mountains, thick low-permeability intervals of silt and clay that separate the ground-water flow system into deep-confined and shallow-unconfined systems, ephemeral-channel recharge, and seasonal variations in ground-water discharge by wells and evapotranspiration. Steady-state and transient conditions during 1902-2003 were simulated by using a five-layer numerical ground- water flow model representing multiple hydrogeologic units. Hydraulic properties of model layers, streamflow, and evapotranspiration rates were estimated as part of the calibration process by using observed water levels, vertical hydraulic gradients, streamflow, and estimated evapotranspiration rates as constraints. Simulations approximate observed water-level trends throughout most of the model area and streamflow trends at the Charleston streamflow-gaging station on the San Pedro River. Differences in observed and simulated water levels, streamflow, and evapotranspiration could be reduced through simulation of climate-related variations in recharge rates and recharge from flood-flow infiltration.

  5. Using geochemical tracers to distinguish groundwater and parafluvial inflows in rivers (the Avon Catchment, SE Australia)

    Science.gov (United States)

    Cartwright, I.; Hofmann, H.

    2015-09-01

    Understanding the location and magnitude of groundwater inflows to rivers is important for the protection of riverine ecosystems and the management of connected groundwater and surface water systems. Downstream trends in 222Rn activities and Cl concentrations in the Avon River, southeast Australia, implies that it contains alternating gaining and losing reaches. 222Rn activities of up to 3690 Bq m-3 imply that inflows are locally substantial (up to 3.1 m3 m-1 day-1). However, if it assumed that these inflows are solely from groundwater, the net groundwater inflows during low-flow periods exceed the measured increase in streamflow along the Avon River by up to 490 %. Uncertainties in the 222Rn activities of groundwater, the gas transfer coefficient, and the degree of hyporheic exchange cannot explain this discrepancy. It is proposed that a significant volume of the total calculated inflows into the Avon River represents water that exfiltrates from the river, flows through parafluvial sediments, and subsequently re-enters the river in the gaining reaches. This returning parafluvial flow has high 222Rn activities due to 222Rn emanations from the alluvial sediments. The riffle sections of the Avon River commonly have steep longitudinal gradients and may transition from losing at their upstream end to gaining at the downstream end and parafluvial flow through the sediment banks on meanders and point bars may also occur. Parafluvial flow is likely to be important in rivers with coarse-grained alluvial sediments on their floodplains and failure to quantify the input of 222Rn from parafluvial flow will result in overestimating groundwater inflows to rivers.

  6. Groundwater and Terrestrial Water Storage

    Science.gov (United States)

    Rodell, Matthew; Chambers, Don P.; Famiglietti, James S.

    2011-01-01

    Most people think of groundwater as a resource, but it is also a useful indicator of climate variability and human impacts on the environment. Groundwater storage varies slowly relative to other non-frozen components of the water cycle, encapsulating long period variations and trends in surface meteorology. On seasonal to interannual timescales, groundwater is as dynamic as soil moisture, and it has been shown that groundwater storage changes have contributed to sea level variations. Groundwater monitoring well measurements are too sporadic and poorly assembled outside of the United States and a few other nations to permit direct global assessment of groundwater variability. However, observational estimates of terrestrial water storage (TWS) variations from the GRACE satellites largely represent groundwater storage variations on an interannual basis, save for high latitude/altitude (dominated by snow and ice) and wet tropical (surface water) regions. A figure maps changes in mean annual TWS from 2009 to 2010, based on GRACE, reflecting hydroclimatic conditions in 2010. Severe droughts impacted Russia and the Amazon, and drier than normal weather also affected the Indochinese peninsula, parts of central and southern Africa, and western Australia. Groundwater depletion continued in northern India, while heavy rains in California helped to replenish aquifers that have been depleted by drought and withdrawals for irrigation, though they are still below normal levels. Droughts in northern Argentina and western China similarly abated. Wet weather raised aquifer levels broadly across western Europe. Rains in eastern Australia caused flooding to the north and helped to mitigate a decade long drought in the south. Significant reductions in TWS seen in the coast of Alaska and the Patagonian Andes represent ongoing glacier melt, not groundwater depletion. Figures plot time series of zonal mean and global GRACE derived non-seasonal TWS anomalies (deviation from the mean of

  7. Characterization of groundwater flow in the environment of the Boom Clay (Campine, Belgium)

    International Nuclear Information System (INIS)

    Gedeon, M.; Labat, S.; Wemaere, I.; Wouters, L.

    2010-01-01

    -east of Belgium. The North-eastern Belgium model (NEB-2002) represents the second update of previous regional models of the north-eastern Belgium aquifer system for the reference site at Mol-Dessel dating from 1984 and 1992. It aimed at modelling the groundwater system both above and below the Boom Clay. Since the groundwater regimes differ substantially above and below the Boom Clay, the modelling results were conceptually divided into one representing the original and one representing the evolving state of the aquifers below the Boom Clay. This division was based on existence of excessive pumping of the aquifers below the Boom Clay that has caused continuous decrease of the groundwater levels during the last 50 years. Since such transient situation occurs in the aquifers below the Boom Clay a steady-state model cannot be used to describe the long-term equilibrium of the aquifer system. The Deep aquifer pumping model (DAP model) focuses on the transient behaviour of the confined parts of the aquifers located below the Boom Clay. The aim of the model was to reconstruct the history of pumping in the aquifers below the Boom Clay and fit the simulated heads to the observed values. It is, of course, impossible to precisely predict the evolution towards the future; however, the results indicate a possible extent of hydraulic gradient change induced by pumping. The Neogene aquifer model (NAM model) simulates the groundwater flow in the aquifers above the Boom Clay. The NAM model is enclosed by the natural no-flow boundaries of the river catchments. The Nete catchment is simulated with two principal rivers: Kleine Nete and Grote Nete rivers. The modelled area is smaller in respect to the NEB-2002 model, which allows more detailed schematization. The vertical division of the Neogene aquifer model allows for later incorporation of a more detailed scale model simulating transport of radionuclide contamination. The NAM model is numerically optimised to overcome the problem of

  8. Innovative technologies for groundwater cleanup

    International Nuclear Information System (INIS)

    Yow, J.L. Jr.

    1992-09-01

    These notes provide a broad overview of current developments in innovative technologies for groundwater cleanup. In this context, groundwater cleanup technologies include site remediation methods that deal with contaminants in ground water or that may move from the vadose zone into ground water. This discussion attempts to emphasize approaches that may be able to achieve significant improvements in groundwater cleanup cost or effectiveness. However, since data for quantitative performance and cost comparisons of new cleanup methods are scarce, preliminary comparisons must be based on the scientific approach used by each method and on the site-specific technical challenges presented by each groundwater contamination situation. A large number of technical alternatives that are now in research, development, and testing can be categorized by the scientific phenomena that they employ and by the site contamination situations that they treat. After reviewing a representative selection of these technologies, one of the new technologies, the Microbial Filter method, is discussed in more detail to highlight a promising in situ groundwater cleanup technology that is now being readied for field testing

  9. Microbial DNA; a possible tracer of groundwater

    Science.gov (United States)

    Sugiyama, Ayumi; Segawa, Takuya; Furuta, Tsuyumi; Nagaosa, Kazuyo; Tsujimura, Maki; Kato, Kenji

    2017-04-01

    Though chemical analysis of groundwater shows an averaged value of chemistry of the examined water which was blended by various water with different sources and routes in subsurface environment, microbial DNA analysis may suggest the place where they originated, which may give information of the source and transport routes of the water examined. A huge amount of groundwater is stored in lava layer with maximum depth of 300m in Mt. Fuji (3,776m asl ), the largest volcanic mountain in Japan. Although the density of prokaryotes was low in the examined groundwater of Mt. Fuji, thermophilic prokaryotes as Thermoanaerobacterales, Gaiellales and Thermoplasmatales were significantly detected. They are optimally adapted to the temperature higher than 40oC. This finding suggests that at least some of the source of the examined groundwater was subsurface environment with 600m deep or greater, based on a temperature gradient of 4oC/100m and temperature of spring water ranges from 10 to 15oC in the foot of Mt. Fuji. This depth is far below the lava layer. Thus, the groundwater is not simply originated from the lava layer. In addition to those findings, we observed a very fast response of groundwater just a couple of weeks after the heavy rainfall exceeding 2 or 300 mm/event in Mt. Fuji. The fast response was suggested by a sharp increase in bacterial abundance in spring water located at 700m in height in the west foot of Mt. Fuji, where the average recharge elevation of groundwater was estimated to be 1,500m - 1,700m (Kato et. al. EGU 2016). This increase was mainly provided by soil bacteria as Burkholderiales, which might be detached from soil by strengthened subsurface flow caused by heavy rainfall. This suggests that heavy rainfall promotes shallow subsurface flow contributing to the discharge in addition to the groundwater in the deep aquifer. Microbial DNA, thus could give information about the route of the examined groundwater, which was never elucidated by analysis of

  10. Spatial Isotopic Characterization of Slovak Groundwaters

    Energy Technology Data Exchange (ETDEWEB)

    Povinec, P. P.; Sivo, A.; Breier, R.; Richtarikova, M. [Comenius University, Faculty of Mathematics, Physics and Informatics, Bratislava (Slovakia); Zenisova, Z. [Comenius University, Faculty of Natural Sciences, Bratislava (Slovakia); Aggarwal, P. K.; Araguas Araguas, L. [International Atomic Energy Agency, Isotope Hydrology Section, Vienna (Austria)

    2013-07-15

    Zitny ostrov (Rye Island) in the south west of Slovakia is the largest groundwater reservoir in Central Europe (about 10 Gm{sup 3}). Groundwater contamination with radionuclides, heavy metals and organic compounds from the Danube River and local industrial and agricultural activities has recently been of great concern. Geostatistical analysis of experimental isotope data has been carried out with the aim of better understanding groundwater dynamics. For this purpose, spatial variations in the distribution of water isotopes and radiocarbon in the groundwater of Zitny ostrov have been evaluated. Subsurface water profiles showed enriched {delta}{sup 18}O levels at around 20 m water depth, and depleted values below 30 m, which are similar to those observed in the Danube River. The core of the subsurface {sup 14}C profiles represents contemporary groundwater with {sup 14}C values above 80 pMc. (author)

  11. Estimates of Nutrient Loading by Ground-Water Discharge into the Lynch Cove Area of Hood Canal, Washington

    Science.gov (United States)

    Simonds, F. William; Swarzenski, Peter W.; Rosenberry, Donald O.; Reich, Christopher D.; Paulson, Anthony J.

    2008-01-01

    field investigations show that ground-water discharge into the Lynch Cove area of Hood Canal is highly dynamic and strongly affected by the large tidal range. In areas with a steep shoreline and steep hydraulic gradient, ground-water discharge is spatially concentrated in or near the intertidal zone, with increased discharge during low tide. Topographically flat areas with weak hydraulic gradients had more spatial variability, including larger areas of seawater recirculation and more widely dispersed discharge. Measured total-dissolved-nitrogen concentrations in ground water ranged from below detection limits to 2.29 milligrams per liter and the total load entering Lynch Cove was estimated to be approximately 98 ? 10.3 metric tons per year (MT/yr). This estimate is based on net freshwater seepage rates from Lee-type seepage meter measurements and can be compared to estimates derived from geochemical tracer mass balance estimates (radon and radium) of 231 to 749 MT/yr, and previous water-mass-balance estimates (14 to 47 MT/ yr). Uncertainty in these loading estimates is introduced by complex biogeochemical cycles of relevant nutrient species, the representativeness of measurement sites, and by energetic dynamics at the coastal aquifer-seawater interface caused by tidal forcing.

  12. A Review of Distributed Parameter Groundwater Management Modeling Methods

    Science.gov (United States)

    Gorelick, Steven M.

    1983-04-01

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

  13. 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

    groundwater flow trends south or south-west in the repository area. The range of variation of the hydraulic gradient immediately outside the repository was studied in the direction of the flow routes from the repository. The gradient outside the eastern repository varies between 1.5 % and 4.0 % (average 2.5 %). The corresponding range for the western repository is between 0.7 % and 0.9 % (average 0.8 %). The nodal hydraulic gradient of the two- dimensional elements representing the eastern repository varies between 0.2 % and 2.0 % (average 1.2 %). In the western part the respective range is from 0.2 % to 0.6 % (average 0.4 %). (orig.) 34 refs.

  14. Regional-to-site scale groundwater flow in Kivetty

    International Nuclear Information System (INIS)

    Kattilakoski, E.; Meszaros, F.

    1999-04-01

    groundwater flow trends south or south-west in the repository area. The range of variation of the hydraulic gradient immediately outside the repository was studied in the direction of the flow routes from the repository. The gradient outside the eastern repository varies between 1.5 % and 4.0 % (average 2.5 %). The corresponding range for the western repository is between 0.7 % and 0.9 % (average 0.8 %). The nodal hydraulic gradient of the two- dimensional elements representing the eastern repository varies between 0.2 % and 2.0 % (average 1.2 %). In the western part the respective range is from 0.2 % to 0.6 % (average 0.4 %). (orig.)

  15. Geothermal gradients in Iraqi Kurdistan deduced from bottom hole temperatures

    OpenAIRE

    Abdula, Rzger A.

    2016-01-01

    Bottom hole temperature (BHT) data from 12 oil wells in Iraqi Kurdistan were used to obtain the thermal trend of Iraqi Kurdistan. Due to differences in thermal conductivity of rocks and groundwater movement, variations in geothermal gradients were observed. The highest geothermal gradient (29.2 °C/km) was found for well Taq Taq-8 in the Low Folded Zone (central part of the area). The lowest geothermal gradients (14.9 °C/km) were observed for well Bekhme-1 in the High Folded Zone (northern and...

  16. Coupling of hydraulic and electric gradients in sandy soils

    Energy Technology Data Exchange (ETDEWEB)

    Gregolec, G.; Zorn, R.; Kurzbach, A.; Roehl, K.E.; Czurda, K. [Dept. of Applied Geology, Univ. Karlsruhe (Germany)

    2001-07-01

    Laboratory studies were conducted to investigate the influence of hydraulic gradient on the migration of ions caused by an applied dc electric field. The model soil used was a uniform sand which was placed into an electrokinetic cell and saturated with sodium chloride solution. Applying only an electric gradient, steady state conditions are reached where the concentration distribution of sodium and chloride coincides with a theoretical model. The combination of electric and hydraulic gradients shows that it is possible to hinder ions from moving with the groundwater flow by applying an electric field. (orig.)

  17. Groundwater Interference

    Data.gov (United States)

    Vermont Center for Geographic Information — "This is a searchable database representing over 40 years of hydrogeologic information based on yield testing required for new and existing public water supply...

  18. Environmental isotope and hydrochemical investigation of Bauru and Botucatu groundwaters, Parana basin, Brazil

    International Nuclear Information System (INIS)

    Kimmelmann, A.

    1991-06-01

    A combined hydrogeochemical and environmental isotope investigation is being carried out in the Bauru- and Botucatu groundwaters. Based on former isotope data, the 2 H/ 18 O-, 3 H-, 13 C-, 14 C- and 3 He/ 4 He-contents of representative groundwaters out from the Bauru- and Botucatu-aquifer are now investigated to reveal a possible interaction of the groundwater systems and to correlate 14 C-groundwater residence times with groundwater ages derived from other isotope methods. (author)

  19. Physical hydrogeology and environmental isotopes to constrain the age, origins, and stability of a low-salinity groundwater lens formed by periodic river recharge: Murray Basin, Australia

    Science.gov (United States)

    Cartwright, Ian; Weaver, Tamie R.; Simmons, Craig T.; Fifield, L. Keith; Lawrence, Charles R.; Chisari, Robert; Varley, Simon

    2010-01-01

    SummaryA low-salinity (total dissolved solids, TDS, Australia. Hydraulic heads, surface water elevations, δ 18O values, major ion geochemistry, 14C activities, and 3H concentrations show that the lens is recharged from the Murray River largely through the riverbank with limited recharge through the floodplain. Recharge of the lens occurs mainly at high river levels and the low-salinity groundwater forms baseflow to some river reaches during times of low river levels. Within the lens, flow through the shallow Channel Sands and deeper Parilla Sands aquifers is sub-horizontal. While the Blanchetown Clay locally separates the Channel Sands and the Parilla Sands, the occurrence of recently recharged low-salinity groundwater below the Blanchetown Clay suggests that there is considerable leakage through this unit, implying that it is not an efficient aquitard. The lateral margin of the lens with the regional groundwater (TDS >25,000 mg/L) is marked by a hectometer to kilometer scale transition in TDS concentrations that is not stratigraphically controlled. Rather this boundary represents a mixing zone with the regional groundwater, the position of which is controlled by the rate of recharge from the river. The lens is part of an active and dynamic hydrogeological system that responds over years to decades to changes in river levels. The lens has shrunk during the drought of the late 1990s to the mid 2000s, and it will continue to shrink unless regular high flows in the Murray River are re-established. Over longer timescales, the rise of the regional water table due to land clearing will increase the hydraulic gradient between the regional groundwater and the groundwater in the lens, which will also cause it to degrade. Replacement of low-salinity groundwater in the lens with saline groundwater will ultimately increase the salinity of the Murray River reducing its utility for water supply and impacting riverine ecosystems.

  20. Protein gradient films of fibroin and gelatine.

    Science.gov (United States)

    Claussen, Kai U; Lintz, Eileen S; Giesa, Reiner; Schmidt, Hans-Werner; Scheibel, Thomas

    2013-10-01

    Gradients are a natural design principle in biological systems that are used to diminish stress concentration where materials of differing mechanical properties connect. An interesting example of a natural gradient material is byssus, which anchors mussels to rocks and other hard substrata. Building upon previous work with synthetic polymers and inspired by byssal threads, protein gradient films are cast using glycerine-plasticized gelatine and fibroin exhibiting a highly reproducible and smooth mechanical gradient, which encompasses a large range of modulus from 160 to 550 MPa. The reproducible production of biocompatible gradient films represents a first step towards medical applications. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. 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.

  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. Mixing-induced groundwater denitrification beneath a manured field in southern Alberta, Canada

    International Nuclear Information System (INIS)

    McCallum, J.E.; Ryan, M.C.; Mayer, B.; Rodvang, S.J.

    2008-01-01

    Contamination of shallow groundwater by NO 3 - from manure may occur under fields where manure is spread as fertilizer and for disposal. Attenuation of NO 3 - in groundwater occurs through denitrification under certain conditions, or NO 3 - -contaminated younger groundwater may mix with older groundwater, lowering the NO 3 - concentration. In this study, δ 15 N and δ 18 O values of NO 3 - , and δ 18 O and δ 2 H values in groundwater under a manured field were evaluated to determine if groundwater NO 3 - concentrations were influenced through mixing of shallower, manure-impacted groundwater with older groundwater, or if denitrification was reducing NO 3 - concentrations. The younger groundwater showed clear evidence of manure impact with elevated Cl - (∼85 mg L -1 ) and NO 3 - concentrations (∼50 mg NO 3 -N L -1 ), and δ 15 N and δ 18 O values of NO 3 - consistent with a manure source. Vertical hydraulic gradients and δ 18 O and δ 2 H values in groundwater suggest older, more reduced groundwater is upwelling locally and mixing with the shallow groundwater. Decreasing NO 3 :Cl ratios, decreasing dissolved O 2 concentrations, and increasing δ 15 N and δ 18 O values of NO 3 - suggest that denitrification occurs locally in the aquifer. The extent of denitrification is proportional to the fraction of deeper groundwater in the aquifer. Denitrification apparently does not proceed in the younger, manure-impacted groundwater in the absence of mixing

  4. $L_{0}$ Gradient Projection.

    Science.gov (United States)

    Ono, Shunsuke

    2017-04-01

    Minimizing L 0 gradient, the number of the non-zero gradients of an image, together with a quadratic data-fidelity to an input image has been recognized as a powerful edge-preserving filtering method. However, the L 0 gradient minimization has an inherent difficulty: a user-given parameter controlling the degree of flatness does not have a physical meaning since the parameter just balances the relative importance of the L 0 gradient term to the quadratic data-fidelity term. As a result, the setting of the parameter is a troublesome work in the L 0 gradient minimization. To circumvent the difficulty, we propose a new edge-preserving filtering method with a novel use of the L 0 gradient. Our method is formulated as the minimization of the quadratic data-fidelity subject to the hard constraint that the L 0 gradient is less than a user-given parameter α . This strategy is much more intuitive than the L 0 gradient minimization because the parameter α has a clear meaning: the L 0 gradient value of the output image itself, so that one can directly impose a desired degree of flatness by α . We also provide an efficient algorithm based on the so-called alternating direction method of multipliers for computing an approximate solution of the nonconvex problem, where we decompose it into two subproblems and derive closed-form solutions to them. The advantages of our method are demonstrated through extensive experiments.

  5. Characterization of DOM in landfill leachate polluted groundwater with electrospary LC-MS

    DEFF Research Database (Denmark)

    Persson, L.; Alsberg, T.; Odham, G.

    2001-01-01

    Dissolved organic matter in leachate polluted groundwater, downgradient a landfill, was analysed with electrospray mass spectrometry. The results indicate that the DOM change qualitatively in the gradient, becoming more uniform in functional groups and hydrofobicity. Those changes may affect...

  6. Groundwater Managment Districts

    Data.gov (United States)

    Kansas Data Access and Support Center — This dataset outlines the location of the five Groundwater Management Districts in Kansas. GMDs are locally formed and elected boards for regional groundwater...

  7. Deep groundwater chemistry

    International Nuclear Information System (INIS)

    Wikberg, P.; Axelsen, K.; Fredlund, F.

    1987-06-01

    Starting in 1977 and up till now a number of places in Sweden have been investigated in order to collect the necessary geological, hydrogeological and chemical data needed for safety analyses of repositories in deep bedrock systems. Only crystalline rock is considered and in many cases this has been gneisses of sedimentary origin but granites and gabbros are also represented. Core drilled holes have been made at nine sites. Up to 15 holes may be core drilled at one site, the deepest down to 1000 m. In addition to this a number of boreholes are percussion drilled at each site to depths of about 100 m. When possible drilling water is taken from percussion drilled holes. The first objective is to survey the hydraulic conditions. Core drilled boreholes and sections selected for sampling of deep groundwater are summarized. (orig./HP)

  8. Ecology and living conditions of groundwater fauna

    International Nuclear Information System (INIS)

    Thulin, Barbara; Hahn, Hans Juergen

    2008-09-01

    This report presents the current state of ecological knowledge and applied research relating to groundwater. A conceptual picture is given of groundwater fauna occurrence in regard to Swedish environmental conditions. Interpretation features for groundwater fauna and applications are outlined. Groundwater is one of the largest and oldest limnic habitats populated by a rich and diverse fauna. Both very old species and species occurring naturally in brackish or salt water can be found in groundwater. Groundwater ecosystems are heterotrophic; the fauna depends on imports from the surface. Most species are meiofauna, 0.3-1 mm. The food chain of groundwater fauna is the same as for relatives in surface water and salt water. Smaller animals graze biofilms and detritus, larger animals act facutatively as predators. A difference is that stygobiotic fauna has become highly adapted to its living space and tolerates very long periods without food. Oxygen is a limiting factor, but groundwater fauna tolerates periods with low oxygen concentrations, even anoxic conditions. For longer periods of time a minimum oxygen requirement of 1 mg/l should be fulfilled. Geographic features such as Quaternary glaciation and very old Pliocene river systems are important for distribution patterns on a large spatial scale, but aquifer characteristics are important on a landscape scale. Area diversity is often comparable to surface water diversity. However, site diversity is low in groundwater. Site specific hydrological exchange on a geological facies level inside the aquifer, e.g. porous, fractured and karstic aquifers as well as the hyporheic zone, controls distribution patterns of groundwater fauna. For a better understanding of controlling factors indicator values are suggested. Different adequate sampling methods are available. They are representative for the aquifer, but a suitable number of monitoring wells is required. The existence of groundwater fauna in Sweden is considered as very

  9. Ecology and living conditions of groundwater fauna

    Energy Technology Data Exchange (ETDEWEB)

    Thulin, Barbara [Geo Innova AB (Sweden); Hahn, Hans Juergen [Arbeitsgruppe Grundwasseroekologie, Univ. of Koblenz-Landau (Germany)

    2008-09-15

    This report presents the current state of ecological knowledge and applied research relating to groundwater. A conceptual picture is given of groundwater fauna occurrence in regard to Swedish environmental conditions. Interpretation features for groundwater fauna and applications are outlined. Groundwater is one of the largest and oldest limnic habitats populated by a rich and diverse fauna. Both very old species and species occurring naturally in brackish or salt water can be found in groundwater. Groundwater ecosystems are heterotrophic; the fauna depends on imports from the surface. Most species are meiofauna, 0.3-1 mm. The food chain of groundwater fauna is the same as for relatives in surface water and salt water. Smaller animals graze biofilms and detritus, larger animals act facutatively as predators. A difference is that stygobiotic fauna has become highly adapted to its living space and tolerates very long periods without food. Oxygen is a limiting factor, but groundwater fauna tolerates periods with low oxygen concentrations, even anoxic conditions. For longer periods of time a minimum oxygen requirement of 1 mg/l should be fulfilled. Geographic features such as Quaternary glaciation and very old Pliocene river systems are important for distribution patterns on a large spatial scale, but aquifer characteristics are important on a landscape scale. Area diversity is often comparable to surface water diversity. However, site diversity is low in groundwater. Site specific hydrological exchange on a geological facies level inside the aquifer, e.g. porous, fractured and karstic aquifers as well as the hyporheic zone, controls distribution patterns of groundwater fauna. For a better understanding of controlling factors indicator values are suggested. Different adequate sampling methods are available. They are representative for the aquifer, but a suitable number of monitoring wells is required. The existence of groundwater fauna in Sweden is considered as very

  10. Brackish groundwater in the United States

    Science.gov (United States)

    Stanton, Jennifer S.; Anning, David W.; Brown, Craig J.; Moore, Richard B.; McGuire, Virginia L.; Qi, Sharon L.; Harris, Alta C.; Dennehy, Kevin F.; McMahon, Peter B.; Degnan, James R.; Böhlke, John Karl

    2017-04-05

    For some parts of the Nation, large-scale development of groundwater has caused decreases in the amount of groundwater that is present in aquifer storage and that discharges to surface-water bodies. Water supply in some areas, particularly in arid and semiarid regions, is not adequate to meet demand, and severe drought is affecting large parts of the United States. Future water demand is projected to heighten the current stress on groundwater resources. This combination of factors has led to concerns about the availability of freshwater to meet domestic, agricultural, industrial, mining, and environmental needs. To ensure the water security of the Nation, currently [2016] untapped water sources may need to be developed.Brackish groundwater is an unconventional water source that may offer a partial solution to current and future water demands. In support of the national census of water resources, the U.S. Geological Survey completed the national brackish groundwater assessment to better understand the occurrence and characteristics of brackish groundwater in the United States as a potential water resource. Analyses completed as part of this assessment relied on previously collected data from multiple sources; no new data were collected. Compiled data included readily available information about groundwater chemistry, horizontal and vertical extents and hydrogeologic characteristics of principal aquifers (regionally extensive aquifers or aquifer systems that have the potential to be used as a source of potable water), and groundwater use. Although these data were obtained from a wide variety of sources, the compiled data are biased toward shallow and fresh groundwater resources; data representing groundwater that is at great depths and is saline were not as readily available.One of the most important contributions of this assessment is the creation of a database containing chemical characteristics and aquifer information for the known areas with brackish groundwater

  11. Summary report on groundwater chemistry

    International Nuclear Information System (INIS)

    Lampen, P.; Snellman, M.

    1993-07-01

    The preliminary site investigations for radioactive waste disposal (in Finland) carried out by Teollisuuden Voima Oy (TVO) during the period 1987 to 1992 yielded data on hydrogeochemistry from a total 337 water samples. The main objective of the groundwater chemistry studies was to characterize groundwaters at the investigation sites and, specifically, to create a concept for the mean residence times and evolution of groundwater by means of isotopic analyses. Moreover, the studies yielded input data for geochemical modelling and the performance assessment. Samples were taken from deep boreholes (with a depth of 500 to 1000 m), percussion-drilled boreholes (depth approx. 200 m), flushing-water wells (approx. 100 m) and multi-level pietzometers (approx. 100 m) used in the hydrological tests. The water used for drilling the deep boreholes was taken from local flushing-water wells, whose water was also analyzed in detail. The flushing water used in drilling was marked with two tracers, iodine and uranine, analyzed with two different methods. For reference purposes, samples were also taken from surficial and groundwaters over a large area surrounding the investigation site. Precipitation over a period of at least one year was collected at all the five investigation sites and the samples were analyzed in great detail, particularly with regard to isotopes. Similarly, snow profile samples representing precipitation during the entire winter was taken from each site at least once

  12. Assessment of seawater intrusion and nitrate contamination on the groundwater quality in the Korba coastal plain of Cap-Bon (North-east of Tunisia)

    Science.gov (United States)

    Zghibi, Adel; Tarhouni, Jamila; Zouhri, Lahcen

    2013-11-01

    In recent years, seawater intrusion and nitrate contamination of groundwater have become a growing concern for people in rural areas in Tunisia where groundwater is always used as drinking water. The coastal plain of Korba (north-east of Tunisia) is a typical area where the contamination of the aquifer in the form of saltwater intrusion and high nitrate concentrations is very developed and represents the major consequence of human activities. The objective of this study is to evaluate groundwater resource level, to determine groundwater quality and to assess the risk of NO3- pollution in groundwater using hydrogeochemical tools. Groundwater were sampled and analyzed for physic-chemical parameters: Ca2+, Mg2+, Na+, K+, Cl-, SO42-, HCO3-, NO3-, Total Dissolved Solid and of the physical parameters (pH, electrical conductivity and the temperature). The interpretation of the analytical results is shown numerically and graphically through the ionic deviations, Piper Diagram, seawater fractions and binary diagrams. Moreover, electrical conductivity investigations have been used to identify the location of the major intrusion plumes in this coastal area and to obtain new information on the spatial scales and dynamics of the fresh water-seawater interface. Those processes can be used as indicators of seawater intrusion progression. First, the hydrogeochemical investigation of this aquifer reveals the major sources of contamination, represented by seawater intrusion. Thus, the intensive extraction of groundwater from aquifer reduces freshwater outflow to the sea, creates several drawdown cones and lowering of the water table to as much as 12 m below mean sea level in the center part of the study area especially between Diarr El Hojjej and Tafelloun villages, causing seawater migration inland and rising toward the wells. Moreover, the results of this study revealed the presence of direct cation exchange linked to seawater intrusion and dissolution processes associated with

  13. Groundwater movement through mudrocks - measurement and interpretation

    International Nuclear Information System (INIS)

    Brightman, M.A.; Alexander, J.; Gostelow, T.P.

    1987-12-01

    The parameters which require measurement to determine the fluxes through mudrocks are groundwater head, hydraulic conductivity, porosity, tortuosity, groundwater chemistry, and the semi-permeable membrane properties of the mudrock. A series of measurements have been made at the Harwell Research Site to assess the occurrence and magnitude of the different fluxes across mudrocks. Head measurements have been made through perforations in the mudrocks, and the results broadly fit the previously conceived groundwater flow pattern. Measurement of the chemical potential of groundwaters is straightforward in the aquifers but more difficult in the mudrocks. If mudrocks do not behave as semi-permeable membranes then diffusion will be a more important solute transport process than advection. If mudrocks behave as ideal semi-permeable membranes the relative magnitude of advective and osmotic groundwater flows is largely dependent on the chemical potential gradient. If mudrocks behave as non-ideal semi-permeable membranes then the relative importance of the mechanisms is chiefly determined by the degree of ideality of the membrane. (author)

  14. DOE groundwater protection strategy

    International Nuclear Information System (INIS)

    Lichtman, S.

    1988-01-01

    EH is developing a DOE-wide Groundwater Quality Protection Strategy to express DOE's commitment to the protection of groundwater quality at or near its facilities. This strategy responds to a September 1986 recommendation of the General Accounting Office. It builds on EPA's August 1984 Ground-Water Protection Strategy, which establishes a classification system designed to protect groundwater according to its value and vulnerability. The purposes of DOE's strategy are to highlight groundwater protection as part of current DOE programs and future Departmental planning, to guide DOE managers in developing site-specific groundwater protection practices where DOE has discretion, and to guide DOE's approach to negotiations with EPA/states where regulatory processes apply to groundwater protection at Departmental facilities. The strategy calls for the prevention of groundwater contamination and the cleanup of groundwater commensurate with its usefulness. It would require long-term groundwater protection with reliance on physical rather than institutional control methods. The strategy provides guidance on providing long-term protection of groundwater resources; standards for new remedial actions;guidance on establishing points of compliance; requirements for establishing classification review area; and general guidance on obtaining variances, where applicable, from regulatory requirements. It also outlines management tools to implement this strategy

  15. 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

  16. Self-organization of intracellular gradients during mitosis

    Directory of Open Access Journals (Sweden)

    Fuller Brian G

    2010-01-01

    Full Text Available Abstract Gradients are used in a number of biological systems to transmit spatial information over a range of distances. The best studied are morphogen gradients where information is transmitted over many cell lengths. Smaller mitotic gradients reflect the need to organize several distinct events along the length of the mitotic spindle. The intracellular gradients that characterize mitosis are emerging as important regulatory paradigms. Intracellular gradients utilize intrinsic auto-regulatory feedback loops and diffusion to establish stable regions of activity within the mitotic cytosol. We review three recently described intracellular mitotic gradients. The Ran GTP gradient with its elaborate cascade of nuclear transport receptors and cargoes is the best characterized, yet the dynamics underlying the robust gradient of Ran-GTP have received little attention. Gradients of phosphorylation have been observed on Aurora B kinase substrates both before and after anaphase onset. In both instances the phosphorylation gradient appears to result from a soluble gradient of Aurora B kinase activity. Regulatory properties that support gradient formation are highlighted. Intracellular activity gradients that regulate localized mitotic events bare several hallmarks of self-organizing biologic systems that designate spatial information during pattern formation. Intracellular pattern formation represents a new paradigm in mitotic regulation.

  17. Continuous Groundwater Monitoring Collocated at USGS Streamgages

    Science.gov (United States)

    Constantz, J. E.; Eddy-Miller, C.; Caldwell, R.; Wheeer, J.; Barlow, J.

    2012-12-01

    USGS Office of Groundwater funded a 2-year pilot study collocating groundwater wells for monitoring water level and temperature at several existing continuous streamgages in Montana and Wyoming, while U.S. Army Corps of Engineers funded enhancement to streamgages in Mississippi. To increase spatial relevance with in a given watershed, study sites were selected where near-stream groundwater was in connection with an appreciable aquifer, and where logistics and cost of well installations were considered representative. After each well installation and surveying, groundwater level and temperature were easily either radio-transmitted or hardwired to existing data acquisition system located in streamgaging shelter. Since USGS field personnel regularly visit streamgages during routine streamflow measurements and streamgage maintenance, the close proximity of observation wells resulted in minimum extra time to verify electronically transmitted measurements. After field protocol was tuned, stream and nearby groundwater information were concurrently acquired at streamgages and transmitted to satellite from seven pilot-study sites extending over nearly 2,000 miles (3,200 km) of the central US from October 2009 until October 2011, for evaluating the scientific and engineering add-on value of the enhanced streamgage design. Examination of the four-parameter transmission from the seven pilot study groundwater gaging stations reveals an internally consistent, dynamic data suite of continuous groundwater elevation and temperature in tandem with ongoing stream stage and temperature data. Qualitatively, the graphical information provides appreciation of seasonal trends in stream exchanges with shallow groundwater, as well as thermal issues of concern for topics ranging from ice hazards to suitability of fish refusia, while quantitatively this information provides a means for estimating flux exchanges through the streambed via heat-based inverse-type groundwater modeling. In June

  18. Groundwater Dynamics in Fossil Fractured Carbonate Aquifers in Eastern Arabian Peninsula

    Science.gov (United States)

    Farag, A. Z. A.; Heggy, E.; Helal, M.; Thirunavukkarasu, D.; Scabbia, G.; Palmer, E. M.

    2017-12-01

    The Eastern Arabian Peninsula, notably the Qatar Peninsula, represents one of the highest natural groundwater discharge areas for the Arabian platform fossil aquifer system. Groundwater flow dynamics in these aquifers trace the paleoclimatic conditions that have prevailed the Arabian Peninsula during the Quaternary. In such settings, connections between aquifers strongly affect the flow dynamics, water quality and availability as well as karst formation and landscape evolution. Geological structures such as folds, faults and fractures are central to aquifer connectivity, yet their role on groundwater flow is poorly understood. Herein, we performed a detailed mapping of exposed and buried structural features in Qatar using Landsat, Sentinel and ALOS-PalSAR scenes, correlated with field and laboratory measurements to understand their role in aquifer connectivity and groundwater dynamics. Our results suggest that E-W oriented fold-related faults act as vertical conduits along which artesian upward leakages from the deep aquifers (e.g. Aruma and Umm er Radhuma) take place into the shallower aquifers (e.g. Rus and Dammam). Evidence includes: (1) the high potentiometric surfaces of deep aquifers (6 to 25 m amsl) compare to the shallower aquifers (2-3 m amsl for the same region); (2) anomalous elevation of groundwater levels and steeper hydraulic gradients in densely faulted regions; (3) mixed isotopic composition in shallow aquifers (δ18O: -5 to -2 ‰, δ2H: -40 to -10 ‰) between reported deep fossil waters (δ18O: -6.3 ‰, δ2H: -55 ‰) and modern meteoric waters (weighted average: δ18O: -0.6 ‰, δ2H: 4 ‰); (4) abundant meso-crystalline fibrous gypsum veins along fault zones in the Dammam Formation (up to 28 m amsl) in southern Qatar where the anhydritic member of the Rus Formation predominates the subsurface leading to gypsum oversaturation of groundwater. The similarity of crystal morphology (platy crystals under SEM), mineralogical compositions from XRD

  19. Evaluation of the Validity of Groundwater Samples Obtained Using the Purge Water Management System at SRS

    International Nuclear Information System (INIS)

    Beardsley, C.C.

    1999-01-01

    As part of the demonstration testing of the Purge Water Management System (PWMS) technology at the Savannah River Site (SRS), four wells were equipped with PWMS units in 1997 and a series of sampling events were conducted at each during 1997-1998. Three of the wells were located in A/M Area while the fourth was located at the Old Radioactive Waste Burial Ground in the General Separations Area.The PWMS is a ''closed-loop'', non-contact, system used to collect and return purge water to the originating aquifer after a sampling event without having significantly altered the water quality. One of the primary concerns as to its applicability at SRS, and elsewhere, is whether the PWMS might resample groundwater that is returned to the aquifer during the previous sampling event. The purpose of the present investigation was to compare groundwater chemical analysis data collected at the four test wells using the PWMS vs. historical data collected using the standard monitoring program methodology to determine if the PWMS provides representative monitoring samples.The analysis of the groundwater chemical concentrations indicates that the PWMS sampling methodology acquired representative groundwater samples at monitoring wells ABP-1A, ABP-4, ARP-3 and BGO-33C. Representative groundwater samples are achieved if the PWMS does not resample groundwater that has been purged and returned during a previous sampling event. Initial screening calculations, conducted prior to the selection of these four wells, indicated that groundwater velocities were high enough under the ambient hydraulic gradients to preclude resampling from occurring at the time intervals that were used at each well. Corroborating evidence included a tracer test that was conducted at BGO-33C, the high degree of similarity between analyte concentrations derived from the PWMS samples and those obtained from historical protocol sampling, as well as the fact that PWMS data extend all previously existing concentration

  20. Terrestrial water load and groundwater fluctuation in the Bengal Basin

    NARCIS (Netherlands)

    Burgess, W.G.; Shamsudduha, M.; Taylor, R.G.; Zahid, A.; Ahmed, K.M.; Mukherjee, A.; Lapworth, D.J.; Bense, V.F.

    2017-01-01

    Groundwater-level fluctuations represent hydraulic responses to changes in groundwater storage due to aquifer recharge and drainage as well as to changes in stress that include water mass loading and unloading above the aquifer surface. The latter 'poroelastic' response of confined aquifers is a

  1. Radioactivity in groundwater along the borders of Oman and UAE

    DEFF Research Database (Denmark)

    Murad, A.; Alshamsi, D.; Hou, Xiaolin

    2014-01-01

    Characterizing the quality and radioactivity of groundwater is vital as it represents valuable resource in arid regions. Here we present radioactivity level in groundwater collected from wells in a region along the border between Sultanate of Oman and United Arab Emirates (UAE). The aquifers...

  2. Groundwater detection monitoring system design under conditions of uncertainty

    NARCIS (Netherlands)

    Yenigül, N.B.

    2006-01-01

    Landfills represent a wide-spread and significant threat to groundwater quality. In this thesis a methodology was developed for the design of optimal groundwater moni-toring system design at landfill sites under conditions of uncertainty. First a decision analysis approach was presented for optimal

  3. Travelling gradient thermocouple calibration

    International Nuclear Information System (INIS)

    Broomfield, G.H.

    1975-01-01

    A short discussion of the origins of the thermocouple EMF is used to re-introduce the idea that the Peltier and Thompson effects are indistinguishable from one another. Thermocouples may be viewed as devices which generate an EMF at junctions or as integrators of EMF's developed in thermal gradients. The thermal gradient view is considered the more appropriate, because of its better accord with theory and behaviour, the correct approach to calibration, and investigation of service effects is immediately obvious. Inhomogeneities arise in thermocouples during manufacture and in service. The results of travelling gradient measurements are used to show that such effects are revealed with a resolution which depends on the length of the gradient although they may be masked during simple immersion calibration. Proposed tests on thermocouples irradiated in a nuclear reactor are discussed

  4. Quaternion Gradient and Hessian

    OpenAIRE

    Xu, Dongpo; Mandic, Danilo P.

    2014-01-01

    The optimization of real scalar functions of quaternion variables, such as the mean square error or array output power, underpins many practical applications. Solutions typically require the calculation of the gradient and Hessian. However, real functions of quaternion variables are essentially nonanalytic, which are prohibitive to the development of quaternion-valued learning systems. To address this issue, we propose new definitions of quaternion gradient and Hessian, based on the novel gen...

  5. Geothermal gradients in Iraqi Kurdistan deduced from bottom hole temperatures

    Directory of Open Access Journals (Sweden)

    Rzger A. Abdula

    2017-09-01

    Full Text Available Bottom hole temperature (BHT data from 12 oil wells in Iraqi Kurdistan were used to obtain the thermal trend of Iraqi Kurdistan. Due to differences in thermal conductivity of rocks and groundwater movement, variations in geothermal gradients were observed. The highest geothermal gradient (29.2 °C/km was found for well Taq Taq-8 in the Low Folded Zone (central part of the area. The lowest geothermal gradients (14.9 °C/km were observed for well Bekhme-1 in the High Folded Zone (northern and northeastern parts of the area. The average regional geothermal gradient for Iraqi Kurdistan is 21 °C/km.

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

    Science.gov (United States)

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

    2006-12-01

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

  7. Osmosis in groundwater : Chemical and electrical extensions to Darcy's Law

    NARCIS (Netherlands)

    Bader, S.

    2005-01-01

    In problems of groundwater flow and solute transport in clayey soils subject to salt concentration gradients, chemical and electro-osmosis can be too important to disregard, as is commonly done in geohydrology. In this thesis, we consider the quantification of these couple effects to be able to

  8. Gradient Alloy for Optical Packaging

    Data.gov (United States)

    National Aeronautics and Space Administration — Advances in additive manufacturing, such as Laser Engineered Net Shaping (LENS), enables the fabrication of compositionally gradient microstructures, i.e. gradient...

  9. Effect of Pumping on Groundwater Levels: A Case Study

    Science.gov (United States)

    Sindhu, G.; Vijayachandran, Lekshmi

    2018-03-01

    Groundwater is a major source for drinking and domestic purposes. Nowadays, extensive pumping has become a major issue of concern since pumping has led to rapid decline in the groundwater table, thus imposing landward gradient, leading to saline water intrusion especially in coastal areas. Groundwater pumping has seen its utmost effect on coastal aquifer systems, where the sea-ward gradient gets disturbed due to anthropogenic influences. Hence, a groundwater flow modelling of an aquifer system is essential for understanding the various hydro-geologic conditions, which can be used to study the responses of the aquifer system with regard to various pumping scenarios. Besides, a model helps to predict the water levels for the future period with respect to changing environment. In this study, a finite element groundwater flow model of a coastal aquifer system at Aakulam, Trivandrum district is developed, calibrated and simulated using the software Finite Element subsurface Flow system (FEFLOW 6.2).This simulated model is then used to predict the groundwater levels for a future 5 year period during pre monsoon and post monsoon season.

  10. Effect of Pumping on Groundwater Levels: A Case Study

    Science.gov (United States)

    Sindhu, G.; Vijayachandran, Lekshmi

    2018-06-01

    Groundwater is a major source for drinking and domestic purposes. Nowadays, extensive pumping has become a major issue of concern since pumping has led to rapid decline in the groundwater table, thus imposing landward gradient, leading to saline water intrusion especially in coastal areas. Groundwater pumping has seen its utmost effect on coastal aquifer systems, where the sea-ward gradient gets disturbed due to anthropogenic influences. Hence, a groundwater flow modelling of an aquifer system is essential for understanding the various hydro-geologic conditions, which can be used to study the responses of the aquifer system with regard to various pumping scenarios. Besides, a model helps to predict the water levels for the future period with respect to changing environment. In this study, a finite element groundwater flow model of a coastal aquifer system at Aakulam, Trivandrum district is developed, calibrated and simulated using the software Finite Element subsurface Flow system (FEFLOW 6.2).This simulated model is then used to predict the groundwater levels for a future 5 year period during pre monsoon and post monsoon season.

  11. Groundwater sustainability strategies

    Science.gov (United States)

    Gleeson, Tom; VanderSteen, Jonathan; Sophocleous, Marios A.; Taniguchi, Makoto; Alley, William M.; Allen, Diana M.; Zhou, Yangxiao

    2010-01-01

    Groundwater extraction has facilitated significant social development and economic growth, enhanced food security and alleviated drought in many farming regions. But groundwater development has also depressed water tables, degraded ecosystems and led to the deterioration of groundwater quality, as well as to conflict among water users. The effects are not evenly spread. In some areas of India, for example, groundwater depletion has preferentially affected the poor. Importantly, groundwater in some aquifers is renewed slowly, over decades to millennia, and coupled climate–aquifer models predict that the flux and/or timing of recharge to many aquifers will change under future climate scenarios. Here we argue that communities need to set multigenerational goals if groundwater is to be managed sustainably.

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

    Science.gov (United States)

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

    2017-12-01

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

  13. 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.

  14. Nitrate in groundwater of the United States, 1991-2003

    Science.gov (United States)

    Burow, Karen R.; Nolan, Bernard T.; Rupert, Michael G.; Dubrovsky, Neil M.

    2010-01-01

    An assessment of nitrate concentrations in groundwater in the United States indicates that concentrations are highest in shallow, oxic groundwater beneath areas with high N inputs. During 1991-2003, 5101 wells were sampled in 51 study areas throughout the U.S. as part of the U.S. Geological Survey National Water-Quality Assessment (NAWQA) program. The well networks reflect the existing used resource represented by domestic wells in major aquifers (major aquifer studies), and recently recharged groundwater beneath dominant land-surface activities (land-use studies). Nitrate concentrations were highest in shallow groundwater beneath agricultural land use in areas with well-drained soils and oxic geochemical conditions. Nitrate concentrations were lowest in deep groundwater where groundwater is reduced, or where groundwater is older and hence concentrations reflect historically low N application rates. Classification and regression tree analysis was used to identify the relative importance of N inputs, biogeochemical processes, and physical aquifer properties in explaining nitrate concentrations in groundwater. Factors ranked by reduction in sum of squares indicate that dissolved iron concentrations explained most of the variation in groundwater nitrate concentration, followed by manganese, calcium, farm N fertilizer inputs, percent well-drained soils, and dissolved oxygen. Overall, nitrate concentrations in groundwater are most significantly affected by redox conditions, followed by nonpoint-source N inputs. Other water-quality indicators and physical variables had a secondary influence on nitrate concentrations.

  15. High Gradient Accelerator Research

    International Nuclear Information System (INIS)

    Temkin, Richard

    2016-01-01

    The goal of the MIT program of research on high gradient acceleration is the development of advanced acceleration concepts that lead to a practical and affordable next generation linear collider at the TeV energy level. Other applications, which are more near-term, include accelerators for materials processing; medicine; defense; mining; security; and inspection. The specific goals of the MIT program are: • Pioneering theoretical research on advanced structures for high gradient acceleration, including photonic structures and metamaterial structures; evaluation of the wakefields in these advanced structures • Experimental research to demonstrate the properties of advanced structures both in low-power microwave cold test and high-power, high-gradient test at megawatt power levels • Experimental research on microwave breakdown at high gradient including studies of breakdown phenomena induced by RF electric fields and RF magnetic fields; development of new diagnostics of the breakdown process • Theoretical research on the physics and engineering features of RF vacuum breakdown • Maintaining and improving the Haimson / MIT 17 GHz accelerator, the highest frequency operational accelerator in the world, a unique facility for accelerator research • Providing the Haimson / MIT 17 GHz accelerator facility as a facility for outside users • Active participation in the US DOE program of High Gradient Collaboration, including joint work with SLAC and with Los Alamos National Laboratory; participation of MIT students in research at the national laboratories • Training the next generation of Ph. D. students in the field of accelerator physics.

  16. Dynamics of Agricultural Groundwater Extraction

    NARCIS (Netherlands)

    Hellegers, P.J.G.J.; Zilberman, D.; Ierland, van E.C.

    2001-01-01

    Agricultural shallow groundwater extraction can result in desiccation of neighbouring nature reserves and degradation of groundwater quality in the Netherlands, whereas both externalities are often not considered when agricultural groundwater extraction patterns are being determined. A model is

  17. Sampling art for ground-water monitoring wells in nuclide migration

    International Nuclear Information System (INIS)

    Liu Wenyuan; Tu Guorong; Dang Haijun; Wang Xuhui; Ke Changfeng

    2010-01-01

    Ground-Water sampling is one of the key parts in field nuclide migration. The objective of ground-water sampling program is to obtain samples that are representative of formation-quality water. In this paper, the ground-water sampling standards and the developments of sampling devices are reviewed. We also designed the sampling study projects which include the sampling methods, sampling parameters and the elementary devise of two types of ground-Water sampling devices. (authors)

  18. A hybrid machine learning model to estimate nitrate contamination of production zone groundwater in the Central Valley, California

    Science.gov (United States)

    Ransom, K.; Nolan, B. T.; Faunt, C. C.; Bell, A.; Gronberg, J.; Traum, J.; Wheeler, D. C.; Rosecrans, C.; Belitz, K.; Eberts, S.; Harter, T.

    2016-12-01

    A hybrid, non-linear, machine learning statistical model was developed within a statistical learning framework to predict nitrate contamination of groundwater to depths of approximately 500 m below ground surface in the Central Valley, California. A database of 213 predictor variables representing well characteristics, historical and current field and county scale nitrogen mass balance, historical and current landuse, oxidation/reduction conditions, groundwater flow, climate, soil characteristics, depth to groundwater, and groundwater age were assigned to over 6,000 private supply and public supply wells measured previously for nitrate and located throughout the study area. The machine learning method, gradient boosting machine (GBM) was used to screen predictor variables and rank them in order of importance in relation to the groundwater nitrate measurements. The top five most important predictor variables included oxidation/reduction characteristics, historical field scale nitrogen mass balance, climate, and depth to 60 year old water. Twenty-two variables were selected for the final model and final model errors for log-transformed hold-out data were R squared of 0.45 and root mean square error (RMSE) of 1.124. Modeled mean groundwater age was tested separately for error improvement in the model and when included decreased model RMSE by 0.5% compared to the same model without age and by 0.20% compared to the model with all 213 variables. 1D and 2D partial plots were examined to determine how variables behave individually and interact in the model. Some variables behaved as expected: log nitrate decreased with increasing probability of anoxic conditions and depth to 60 year old water, generally decreased with increasing natural landuse surrounding wells and increasing mean groundwater age, generally increased with increased minimum depth to high water table and with increased base flow index value. Other variables exhibited much more erratic or noisy behavior in

  19. Gradient dissimilation in Mongolian: Implications for diachrony

    DEFF Research Database (Denmark)

    Jatteau, Adèle; Hejná, Michaela

    2018-01-01

    This paper explores the implications of ‘gradient dissimilation’ (Jatteau & Hejná 2016) for the diachronic implementation of dissimilation. Since this sound change is usually considered as typically sporadic, lexically regular cases should result from lexical diffusion. In contrast with this ass......This paper explores the implications of ‘gradient dissimilation’ (Jatteau & Hejná 2016) for the diachronic implementation of dissimilation. Since this sound change is usually considered as typically sporadic, lexically regular cases should result from lexical diffusion. In contrast...... with this assumption, we explore the hypothesis that gradient dissimilation may represent the phonetic precursor of completed, regular dissimilatory processes. Such cases of dissimilation might then be reanalysed as Neogrammarian types of change. To assess this question, we gather and analyse new data from Halh...... Mongolian, a language reported to show gradient dissimilation (Svantesson et al. 2005), and compare it to two completed patterns of dissimilation reconstructed within the Mongolic family: Mongolian Chahar and Monguor. The results suggest that the gradient dissimilation in Halh may represent the phonetic...

  20. Hydrogeology, groundwater seepage, nitrate distribution, and flux at the Raleigh hydrologic research station, Wake County, North Carolina, 2005-2007

    Science.gov (United States)

    McSwain, Kristen Bukowski; Bolich, Richard E.; Chapman, Melinda J.

    2013-01-01

    gradients in the groundwater discharge area near the Neuse River were complex and were affected by fluctuations in river stage, with the exception of a well completed in a diabase dike. Water-quality data from the wells and surface-water sites at the RHRS were collected continuously as well as during periodic sampling events. Surface-water samples collected from a tributary were most similar in chemical composition to groundwater found in the regolith and transition zone. Nitrate (measured as nitrite plus nitrate, as nitrogen) concentrations in the sampled wells and tributary ranged from about 5 to more than 120 milligrams per liter as nitrogen. Waterborne continuous resistivity profiling conducted on the Neuse River in the area of the RHRS measured areas of low apparent resistivity that likely represent groundwater contaminated by high concentrations of nitrate. These areas were located on either side of a diabase dike and at the outfall of two unnamed tributaries. The diabase dike preferentially directed the discharge of groundwater to the Neuse River and may isolate groundwater movement laterally. Discrete temperature measurements made within the pore water beneath the Neuse River revealed seeps of colder groundwater discharging into warmer surface water near a diabase dike. Water-quality samples collected from the pore water beneath the Neuse River indicated that nitrate was present at concentrations as high as 80 milligrams per liter as nitrogen on the RHRS side of the river. The highest concentrations of nitrate were located within pore water collected from an area near a diabase dike that was identified as a suspected seepage area. Hydraulic head was measured and pore water samples were collected from two 140-centimeter-deep (55.1-inch-deep) multiport piezometers that were installed in bed sediments on opposite sides of a diabase dike. The concentration of nitrate in pore water at a suspected seepage area ranged from 42 to 82 milligrams per liter as nitrogen with a

  1. Evaluation of contaminated groundwater cleanup objectives

    International Nuclear Information System (INIS)

    Arquiett, C.; Gerke, M.; Datskou, I.

    1996-01-01

    The US Department of Energy's (DOE's) Environmental Restoration Program will be responsible for remediating the approximately 230 contaminated groundwater sites across the DOE Complex. A major concern for remediation is choosing the appropriate cleanup objective. The cleanup objective chosen will influence the risk to the nearby public during and after remediation; risk to remedial and non-involved workers during remediation; and the cost of remediation. This paper discusses the trends shown in analyses currently being performed at Oak Ridge National Laboratories' (ORNL's) Center for Risk Management (CRM). To evaluate these trends, CRM is developing a database of contaminated sites. This paper examines several contaminated groundwater sites selected for assessment from CRM's data base. The sites in this sample represent potential types of contaminated groundwater sites commonly found at an installation within DOE. The baseline risk from these sites to various receptors is presented. Residual risk and risk during remediation is reported for different cleanup objectives. The cost associated with remediating to each of these objectives is also estimated for each of the representative sites. Finally, the general trends of impacts as a function of cleanup objective will be summarized. The sites examined include the Savannah River site, where there was substantial ground pollution from radionuclides, oil, coal stockpiles, and other forms of groundwater contamination. The effects of various types of groundwater contamination on various types of future user is described. 4 refs., 3 figs., 2 tabs

  2. Uniform gradient expansions

    CERN Document Server

    Giovannini, Massimo

    2015-01-01

    Cosmological singularities are often discussed by means of a gradient expansion that can also describe, during a quasi-de Sitter phase, the progressive suppression of curvature inhomogeneities. While the inflationary event horizon is being formed the two mentioned regimes coexist and a uniform expansion can be conceived and applied to the evolution of spatial gradients across the protoinflationary boundary. It is argued that conventional arguments addressing the preinflationary initial conditions are necessary but generally not sufficient to guarantee a homogeneous onset of the conventional inflationary stage.

  3. High gradient superconducting quadrupoles

    International Nuclear Information System (INIS)

    Lundy, R.A.; Brown, B.C.; Carson, J.A.; Fisk, H.E.; Hanft, R.H.; Mantsch, P.M.; McInturff, A.D.; Remsbottom, R.H.

    1987-07-01

    Prototype superconducting quadrupoles with a 5 cm aperture and gradient of 16 kG/cm have been built and tested as candidate magnets for the final focus at SLC. The magnets are made from NbTi Tevatron style cable with 10 inner and 14 outer turns per quadrant. Quench performance and multipole data are presented. Design and data for a low current, high gradient quadrupole, similar in cross section but wound with a cable consisting of five insulated conductors are also discussed

  4. Building groundwater modeling capacity in Mongolia

    Science.gov (United States)

    Valder, Joshua F.; Carter, Janet M.; Anderson, Mark T.; Davis, Kyle W.; Haynes, Michelle A.; Dorjsuren Dechinlhundev,

    2016-06-16

    Ulaanbaatar, the capital city of Mongolia (fig. 1), is dependent on groundwater for its municipal and industrial water supply. The population of Mongolia is about 3 million people, with about one-half the population residing in or near Ulaanbaatar (World Population Review, 2016). Groundwater is drawn from a network of shallow wells in an alluvial aquifer along the Tuul River. Evidence indicates that current water use may not be sustainable from existing water sources, especially when factoring the projected water demand from a rapidly growing urban population (Ministry of Environment and Green Development, 2013). In response, the Government of Mongolia Ministry of Environment, Green Development, and Tourism (MEGDT) and the Freshwater Institute, Mongolia, requested technical assistance on groundwater modeling through the U.S. Army Corps of Engineers (USACE) to the U.S. Geological Survey (USGS). Scientists from the USGS and USACE provided two workshops in 2015 to Mongolian hydrology experts on basic principles of groundwater modeling using the USGS groundwater modeling program MODFLOW-2005 (Harbaugh, 2005). The purpose of the workshops was to bring together representatives from the Government of Mongolia, local universities, technical experts, and other key stakeholders to build in-country capacity in hydrogeology and groundwater modeling.A preliminary steady-state groundwater-flow model was developed as part of the workshops to demonstrate groundwater modeling techniques to simulate groundwater conditions in alluvial deposits along the Tuul River in the vicinity of Ulaanbaatar. ModelMuse (Winston, 2009) was used as the graphical user interface for MODFLOW for training purposes during the workshops. Basic and advanced groundwater modeling concepts included in the workshops were groundwater principles; estimating hydraulic properties; developing model grids, data sets, and MODFLOW input files; and viewing and evaluating MODFLOW output files. A key to success was

  5. 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

  6. Groundwater Assessment Platform

    OpenAIRE

    Podgorski, Joel; Berg, Michael

    2018-01-01

    The Groundwater Assessment Platform is a free, interactive online GIS platform for the mapping, sharing and statistical modeling of groundwater quality data. The modeling allows users to take advantage of publicly available global datasets of various environmental parameters to produce prediction maps of their contaminant of interest.

  7. Costs of groundwater contamination

    International Nuclear Information System (INIS)

    O'Neil, W.B.; Raucher, R.S.

    1990-01-01

    Two factors determine the cost of groundwater contamination: (1) the ways in which water was being used or was expected to be used in the future and (2) the physical characteristics of the setting that constrain the responses available to regain lost uses or to prevent related damages to human health and the environment. Most contamination incidents can be managed at a low enough cost that uses will not be foreclosed. It is important to take into account the following when considering costs: (1) natural cleansing through recharge and dilution can take many years; (2) it is difficult and costly to identify the exact area and expected path of a contamination plume; and (3) treatment or replacement of contaminated water often may represent the cost-effective strategy for managing the event. The costs of contamination include adverse health effects, containment and remediation, treatment and replacement costs. In comparing the costs and benefits of prevention programs with those of remediation, replacement or treatment, it is essential to adjust the cost/benefit numbers by the probability of their actual occurrence. Better forecasts of water demand are needed to predict more accurately the scarcity of new supply and the associated cost of replacement. This research should include estimates of the price elasticity of water demand and the possible effect on demand of more rational cost-based pricing structures. Research and development of techniques for in situ remediation should be encouraged

  8. Hanford groundwater scenario studies

    International Nuclear Information System (INIS)

    Arnett, R.C.; Gephart, R.E.; Deju, R.A.; Cole, C.R.; Ahlstrom, S.W.

    1977-05-01

    This report documents the results of two Hanford groundwater scenario studies. The first study examines the hydrologic impact of increased groundwater recharge resulting from agricultural development in the Cold Creek Valley located west of the Hanford Reservation. The second study involves recovering liquid radioactive waste which has leaked into the groundwater flow system from a hypothetical buried tank containing high-level radioactive waste. The predictive and control capacity of the onsite Hanford modeling technology is used to evaluate both scenarios. The results of the first study indicate that Cold Creek Valley irrigationis unlikely to cause significant changes in the water table underlying the high-level waste areas or in the movement of radionuclides already in the groundwater. The hypothetical tank leak study showed that an active response (in this case waste recovery) can be modeled and is a possible alternative to passive monitoring of radionuclide movement in the unlikely event that high-level waste is introduced into the groundwater

  9. Increasing the utility of regional water table maps: a new method for estimating groundwater recharge

    Science.gov (United States)

    Gilmore, T. E.; Zlotnik, V. A.; Johnson, M.

    2017-12-01

    Groundwater table elevations are one of the most fundamental measurements used to characterize unconfined aquifers, groundwater flow patterns, and aquifer sustainability over time. In this study, we developed an analytical model that relies on analysis of groundwater elevation contour (equipotential) shape, aquifer transmissivity, and streambed gradient between two parallel, perennial streams. Using two existing regional water table maps, created at different times using different methods, our analysis of groundwater elevation contours, transmissivity and streambed gradient produced groundwater recharge rates (42-218 mm yr-1) that were consistent with previous independent recharge estimates from different methods. The three regions we investigated overly the High Plains Aquifer in Nebraska and included some areas where groundwater is used for irrigation. The three regions ranged from 1,500 to 3,300 km2, with either Sand Hills surficial geology, or Sand Hills transitioning to loess. Based on our results, the approach may be used to increase the value of existing water table maps, and may be useful as a diagnostic tool to evaluate the quality of groundwater table maps, identify areas in need of detailed aquifer characterization and expansion of groundwater monitoring networks, and/or as a first approximation before investing in more complex approaches to groundwater recharge estimation.

  10. The local groundwater regime at the Harwell research site

    International Nuclear Information System (INIS)

    Alexander, J.; Holmes, D.C.

    1983-01-01

    Three deep and two shallow boreholes have been drilled at the Harwell Research Site as part of a national research programme into the feasibility of disposal of low and intermediate level radioactive wastes to geologic formations. Various hydrogeological and geochemical techniques have been employed in these boreholes, each of which samples a separate formation of interest, to determine the pattern of groundwater movement under the research site. Significant vertical hydraulic gradients have been identified which produce vertically downwards groundwater movement from the surface to a depth of 200 m (Corallian aquifer). Groundwater moves vertically upwards, from greater depths, through the Oxford Clay to the Corallian aquifer. However,the apparently very low hydraulic conductivity of the Oxford Clay results in extremely low flow velocities and long transit times. Groundwaters from the Corallian formation possess higher salinities than those of the characteristic regional groundwaters, and preliminary isotopic data suggest that some groundwater mixing with connate waters has occurred. The chemical nature of groundwaters from the Great Oolite Group, suggest that contamination due to the drilling and completion procedure has taken place. Due to the low hydraulic conductivity in this formation clearance of contaminants will require the implementation of a long-term abstraction programme. (author)

  11. Manipulating the Gradient

    Science.gov (United States)

    Gaze, Eric C.

    2005-01-01

    We introduce a cooperative learning, group lab for a Calculus III course to facilitate comprehension of the gradient vector and directional derivative concepts. The lab is a hands-on experience allowing students to manipulate a tangent plane and empirically measure the effect of partial derivatives on the direction of optimal ascent. (Contains 7…

  12. Groundwater Model Validation

    Energy Technology Data Exchange (ETDEWEB)

    Ahmed E. Hassan

    2006-01-24

    Models have an inherent uncertainty. The difficulty in fully characterizing the subsurface environment makes uncertainty an integral component of groundwater flow and transport models, which dictates the need for continuous monitoring and improvement. Building and sustaining confidence in closure decisions and monitoring networks based on models of subsurface conditions require developing confidence in the models through an iterative process. The definition of model validation is postulated as a confidence building and long-term iterative process (Hassan, 2004a). Model validation should be viewed as a process not an end result. Following Hassan (2004b), an approach is proposed for the validation process of stochastic groundwater models. The approach is briefly summarized herein and detailed analyses of acceptance criteria for stochastic realizations and of using validation data to reduce input parameter uncertainty are presented and applied to two case studies. During the validation process for stochastic models, a question arises as to the sufficiency of the number of acceptable model realizations (in terms of conformity with validation data). Using a hierarchical approach to make this determination is proposed. This approach is based on computing five measures or metrics and following a decision tree to determine if a sufficient number of realizations attain satisfactory scores regarding how they represent the field data used for calibration (old) and used for validation (new). The first two of these measures are applied to hypothetical scenarios using the first case study and assuming field data consistent with the model or significantly different from the model results. In both cases it is shown how the two measures would lead to the appropriate decision about the model performance. Standard statistical tests are used to evaluate these measures with the results indicating they are appropriate measures for evaluating model realizations. The use of validation

  13. 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

  14. Hydrochemistry of surface water and groundwater in the shale bedrock, Cross River Basin and Niger Delta Region, Nigeria

    Science.gov (United States)

    Nganje, T. N.; Hursthouse, A. S.; Edet, Aniekan; Stirling, D.; Adamu, C. I.

    2017-05-01

    Water chemistry in the shale bedrock of the Cretaceous-Tertiary of the Cross River and Niger Delta hydrological basins has been investigated using major ions. To carry out a characterization of the water bearing units, 30 and 16 representatives surface and groundwater samples were collected. The evolution of the water is characterized by enhanced content of sodium, calcium and sulphate as a result of leaching of shale rock. The spatial changes in groundwater quality of the area shows an anomalous concentrations of ions in the central parts, while lower values characterize the eastern part of the basin covering Ogoja, Ikom and Odukpani areas. The values of total dissolved solids (TDS) and ions increases down gradient in the direction of groundwater flow. The dissolution of halite and gypsum explains part of the contained Na+, Ca2+, Cl- and SO4 2-, but other processes such as ion exchange, silicate weathering and pyrite oxidation also contribute to water composition. The assessment with contamination indicators such as TDS, hardness, chloride, nitrate and sulphate indicates that the water in area is suitable for human consumption in some locations. Modelling using MINTEQA2 program shows that the water from all the shale water bearing units are under saturated with respect to gypsum.

  15. Use of a three-dimensional model for the analysis of the ground-water flow system in Parker Valley, Arizona and California

    Science.gov (United States)

    Tucci, Patrick

    1982-01-01

    A three-dimensional, finite-difference model was used to simulate ground-water flow conditions in Parker Valley. The study evaluated present knowledge and concepts of the ground-water system and the ability of the model to represent the system. Modeling assumptions and generalized physical parameters that were used may have transfer value in the construction and calibration of models of other basins along the lower Colorado River. The aquifer was simulated in two layers to represent the three-dimensional system. Ground-water conditions were simulated for 1940-41, the mid-1960's, and 1980. Overall model results generally compared favorably with available field information. The model results showed that for 1940-41 the Colorado River was a losing stream through out Parker Valley. Infiltration of surface water from the river was the major source of recharge. The dominant mechanism of discharge was evapotranspiration by phreatophytes. Agricultural development between 1941 and the mid-1960 's resulted in significant changes to the ground-water system. Model results for conditions in the mid-1960 's showed that the Colorado River had become a gaining stream in the northern part of the valley as a result of higher water levels. The rise in water levels was caused by infiltration of applied irrigation water. Diminished water-level gradients from the river in the rest of the valley reduced the amount of infiltration of surface water from the river. Models results for conditions in 1980 showed that ground-water level rises of several feet caused further reduction in the amount of surface-water infiltration from the river. (USGS)

  16. Global depletion of groundwater resources

    NARCIS (Netherlands)

    Wada, Y.; Beek, L.P.H. van; van Kempen, C.M.; Reckman, J.W.T.M.; Vasak, S.; Bierkens, M.F.P.

    2010-01-01

    In regions with frequent water stress and large aquifer systems groundwater is often used as an additional water source. If groundwater abstraction exceeds the natural groundwater recharge for extensive areas and long times, overexploitation or persistent groundwater depletion occurs. Here we

  17. Resilience of Groundwater Impacted by Land Use and Climate Change in a Karst Aquifer, South China.

    Science.gov (United States)

    Guo, Fang; Jiang, Guanghui; Polk, Jason S; Huang, Xiufeng; Huang, Siyu

    2015-11-01

    Changes of groundwater flow and quality were investigated in a subtropical karst aquifer to determine the driving mechanism. Decreases in groundwater flow are more distinct in discharge zones than those in recharge and runoff zones. Long-term measurement of the represented regional groundwater outlet reveals that groundwater discharge decrease by nearly 50% during the dry season. The hydrochemistry of groundwater in the runoff and discharge zones is of poorer quality than in the recharge zone. Indications of intensive land resource exploitation and changes in land use patterns were attributed to changes in groundwater conditions since 1990, but the influence of climate change was likely from 2001, because the water temperature exhibited increasing trends at a mean rate of 0.02 °C/yr even though groundwater depth was high in the aquifer. These conclusions imply the need for further groundwater monitoring and reevaluation to understand the resilience of aquifer during urbanization and development.

  18. Saline groundwater in crystalline bedrock

    International Nuclear Information System (INIS)

    Lampen, P.

    1992-11-01

    The State-of-art report describes research made on deep saline groundwaters and brines found in crystalline bedrock, mainly in site studies for nuclear waste disposal. The occurrence, definitions and classifications of saline groundwaters are reviewed with a special emphasis on the different theories concerning the origins of saline groundwaters. Studies of the saline groundwaters in Finland and Sweden have been reviewed more thoroughly. Also the mixing of different bodies of groundwaters, observations of the contact of saline groundwaters and permafrost, and the geochemical modelling of saline groundwaters as well as the future trends of research have been discussed. (orig.)

  19. The thermal impact of subsurface building structures on urban groundwater resources - A paradigmatic example.

    Science.gov (United States)

    Epting, Jannis; Scheidler, Stefan; Affolter, Annette; Borer, Paul; Mueller, Matthias H; Egli, Lukas; García-Gil, Alejandro; Huggenberger, Peter

    2017-10-15

    Shallow subsurface thermal regimes in urban areas are increasingly impacted by anthropogenic activities, which include infrastructure development like underground traffic lines as well as industrial and residential subsurface buildings. In combination with the progressive use of shallow geothermal energy systems, this results in the so-called subsurface urban heat island effect. This article emphasizes the importance of considering the thermal impact of subsurface structures, which commonly is underestimated due to missing information and of reliable subsurface temperature data. Based on synthetic heat-transport models different settings of the urban environment were investigated, including: (1) hydraulic gradients and conductivities, which result in different groundwater flow velocities; (2) aquifer properties like groundwater thickness to aquitard and depth to water table; and (3) constructional features, such as building depths and thermal properties of building structures. Our results demonstrate that with rising groundwater flow velocities, the heat-load from building structures increase, whereas down-gradient groundwater temperatures decrease. Thermal impacts on subsurface resources therefore have to be related to the permeability of aquifers and hydraulic boundary conditions. In regard to the urban settings of Basel, Switzerland, flow velocities of around 1 md -1 delineate a marker where either down-gradient temperature deviations or heat-loads into the subsurface are more relevant. Furthermore, no direct thermal influence on groundwater resources should be expected for aquifers with groundwater thicknesses larger 10m and when the distance of the building structure to the groundwater table is higher than around 10m. We demonstrate that measuring temperature changes down-gradient of subsurface structures is insufficient overall to assess thermal impacts, particularly in urban areas. Moreover, in areas which are densely urbanized, and where groundwater flow

  20. Bigravity from gradient expansion

    International Nuclear Information System (INIS)

    Yamashita, Yasuho; Tanaka, Takahiro

    2016-01-01

    We discuss how the ghost-free bigravity coupled with a single scalar field can be derived from a braneworld setup. We consider DGP two-brane model without radion stabilization. The bulk configuration is solved for given boundary metrics, and it is substituted back into the action to obtain the effective four-dimensional action. In order to obtain the ghost-free bigravity, we consider the gradient expansion in which the brane separation is supposed to be sufficiently small so that two boundary metrics are almost identical. The obtained effective theory is shown to be ghost free as expected, however, the interaction between two gravitons takes the Fierz-Pauli form at the leading order of the gradient expansion, even though we do not use the approximation of linear perturbation. We also find that the radion remains as a scalar field in the four-dimensional effective theory, but its coupling to the metrics is non-trivial.

  1. Gradient-Index Optics

    Science.gov (United States)

    2010-03-31

    nonimaging design capabilities to incorporate 1. REPORT DATE (DD-MM-YYYY) 4. TITLE AND SUBTITLE 12-04-2011 13. SUPPLEMENTARY NOTES The views, opinions...Box 12211 Research Triangle Park, NC 27709-2211 15. SUBJECT TERMS Imaging Optics, Nonimaging Optics, Gradient Index Optics, Camera, Concentrator...imaging and nonimaging design capabilities to incorporate manufacturable GRIN lenses can provide imaging lens systems that are compact and

  2. Emulation of recharge and evapotranspiration processes in shallow groundwater systems

    Science.gov (United States)

    Doble, Rebecca C.; Pickett, Trevor; Crosbie, Russell S.; Morgan, Leanne K.; Turnadge, Chris; Davies, Phil J.

    2017-12-01

    In shallow groundwater systems, recharge and evapotranspiration are highly sensitive to changes in the depth to water table. To effectively model these fluxes, complex functions that include soil and vegetation properties are often required. Model emulation (surrogate modelling or meta-modelling) can provide a means of incorporating detailed conceptualisation of recharge and evapotranspiration processes, while maintaining the numerical tractability and computational performance required for regional scale groundwater models and uncertainty analysis. A method for emulating recharge and evapotranspiration processes in groundwater flow models was developed, and applied to the South East region of South Australia and western Victoria, which is characterised by shallow groundwater, wetlands and coastal lakes. The soil-vegetation-atmosphere transfer (SVAT) model WAVES was used to generate relationships between net recharge (diffuse recharge minus evapotranspiration from groundwater) and depth to water table for different combinations of climate, soil and land cover types. These relationships, which mimicked previously described soil, vegetation and groundwater behaviour, were combined into a net recharge lookup table. The segmented evapotranspiration package in MODFLOW was adapted to select values of net recharge from the lookup table depending on groundwater depth, and the climate, soil and land use characteristics of each cell. The model was found to be numerically robust in steady state testing, had no major increase in run time, and would be more efficient than tightly-coupled modelling approaches. It made reasonable predictions of net recharge and groundwater head compared with remotely sensed estimates of net recharge and a standard MODFLOW comparison model. In particular, the method was better able to predict net recharge and groundwater head in areas with steep hydraulic gradients.

  3. Hydrogeological controls on spatial patterns of groundwater discharge in peatlands

    Directory of Open Access Journals (Sweden)

    D. K. Hare

    2017-11-01

    Full Text Available Peatland environments provide important ecosystem services including water and carbon storage, nutrient processing and retention, and wildlife habitat. However, these systems and the services they provide have been degraded through historical anthropogenic agricultural conversion and dewatering practices. Effective wetland restoration requires incorporating site hydrology and understanding groundwater discharge spatial patterns. Groundwater discharge maintains wetland ecosystems by providing relatively stable hydrologic conditions, nutrient inputs, and thermal buffering important for ecological structure and function; however, a comprehensive site-specific evaluation is rarely feasible for such resource-constrained projects. An improved process-based understanding of groundwater discharge in peatlands may help guide ecological restoration design without the need for invasive methodologies and detailed site-specific investigation. Here we examine a kettle-hole peatland in southeast Massachusetts historically modified for commercial cranberry farming. During the time of our investigation, a large process-based ecological restoration project was in the assessment and design phases. To gain insight into the drivers of site hydrology, we evaluated the spatial patterning of groundwater discharge and the subsurface structure of the peatland complex using heat-tracing methods and ground-penetrating radar. Our results illustrate that two groundwater discharge processes contribute to the peatland hydrologic system: diffuse lower-flux marginal matrix seepage and discrete higher-flux preferential-flow-path seepage. Both types of groundwater discharge develop through interactions with subsurface peatland basin structure, often where the basin slope is at a high angle to the regional groundwater gradient. These field observations indicate strong correlation between subsurface structures and surficial groundwater discharge. Understanding these general patterns

  4. Hydrogeological controls on spatial patterns of groundwater discharge in peatlands

    Science.gov (United States)

    Hare, Danielle K.; Boutt, David F.; Clement, William P.; Hatch, Christine E.; Davenport, Glorianna; Hackman, Alex

    2017-11-01

    Peatland environments provide important ecosystem services including water and carbon storage, nutrient processing and retention, and wildlife habitat. However, these systems and the services they provide have been degraded through historical anthropogenic agricultural conversion and dewatering practices. Effective wetland restoration requires incorporating site hydrology and understanding groundwater discharge spatial patterns. Groundwater discharge maintains wetland ecosystems by providing relatively stable hydrologic conditions, nutrient inputs, and thermal buffering important for ecological structure and function; however, a comprehensive site-specific evaluation is rarely feasible for such resource-constrained projects. An improved process-based understanding of groundwater discharge in peatlands may help guide ecological restoration design without the need for invasive methodologies and detailed site-specific investigation. Here we examine a kettle-hole peatland in southeast Massachusetts historically modified for commercial cranberry farming. During the time of our investigation, a large process-based ecological restoration project was in the assessment and design phases. To gain insight into the drivers of site hydrology, we evaluated the spatial patterning of groundwater discharge and the subsurface structure of the peatland complex using heat-tracing methods and ground-penetrating radar. Our results illustrate that two groundwater discharge processes contribute to the peatland hydrologic system: diffuse lower-flux marginal matrix seepage and discrete higher-flux preferential-flow-path seepage. Both types of groundwater discharge develop through interactions with subsurface peatland basin structure, often where the basin slope is at a high angle to the regional groundwater gradient. These field observations indicate strong correlation between subsurface structures and surficial groundwater discharge. Understanding these general patterns may allow resource

  5. CHARACTERIZATION OF GROUNDWATER HYDROCHEMISTRY ...

    African Journals Online (AJOL)

    Osondu

    2013-03-01

    Mar 1, 2013 ... It was concluded that water quality of the study area is unsuitable for irrigation ... Key words: Assessment, characterization, Groundwater quality, .... The in-situ measurement was ..... framework of the aquifer in and around East.

  6. 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...

  7. Wetland Groundwater Processes

    National Research Council Canada - National Science Library

    Williams, Greg

    1993-01-01

    This technical note summarizes hydrologic and hydraulic (H AND H) processes and the related terminology that will likely be encountered during an evaluation of the effect of ground-water processes on wetland function...

  8. Natural radionuclides in groundwaters

    International Nuclear Information System (INIS)

    Laul, J.C.

    1990-01-01

    The U-234 and Th-230 radionuclides are highly retarded by factors of 10 4 to 10 5 in basalt groundwater (Hanford) and briny groundwaters from Texas and geothermal brine from the Salton Sea Geothermal Field (SSGF). In basalt groundwaters (low ionic strength), Ra is highly sorbed, while in brines (high ionic strength), Ra is soluble. This is probably because the sorption sites are saturated with Na + and Cl - ions and RaCl 2 is soluble in brines. Pb-210 is soluble in SSGF brine, probably as a chloride complex. The U-234/Th-230 ratios in basalt groundwaters and brines from Texas and SSGF are nearly unity, indicating that U is in the +4 state, suggesting a reducing environment for these aquifers. 19 refs., 3 figs

  9. Natural radionuclides in groundwaters

    International Nuclear Information System (INIS)

    Laul, J.C.

    1992-01-01

    The 234 U and 230 Th radionuclides are highly retarded by factors of 10 4 to 10 5 in basalt groundwater (Hanford) and briny groundwaters from Texas, and geothermal brine form the Salton Sea Geothermal Field (SSGF). In basalt groundwaters (low ionic strength), Ra is highly sorbed, while in brines (high ionic strength), Ra is soluble. This is probably because the sorption sites are saturated with Na + and Cl - ions, and RaCl 2 is soluble in brines. 210 Pb is soluble in SSGF brine, probably as a chloride complex. The 234 U/ 230 Th ratios in basalt groundwaters and brines from Texas and SSGF are nearly unity, indicating that U is in the +4 state, suggesting a reducing environment for these aquifers. (author) 19 refs.; 3 figs

  10. Concentration and size distribution of particles in abstracted groundwater.

    Science.gov (United States)

    van Beek, C G E M; de Zwart, A H; Balemans, M; Kooiman, J W; van Rosmalen, C; Timmer, H; Vandersluys, J; Stuyfzand, P J

    2010-02-01

    Particle number concentrations have been counted and particle size distributions calculated in groundwater derived by abstraction wells. Both concentration and size distribution are governed by the discharge rate: the higher this rate the higher the concentration and the higher the proportion of larger particles. However, the particle concentration in groundwater derived from abstraction wells, with high groundwater flow velocities, is much lower than in groundwater from monitor wells, with minimal flow velocities. This inconsistency points to exhaustion of the particle supply in the aquifer around wells due to groundwater abstraction for many years. The particle size distribution can be described with the help of a power law or Pareto distribution. Comparing the measured particle size distribution with the Pareto distribution shows that particles with a diameter >7 microm are under-represented. As the particle size distribution is dependent on the flow velocity, so is the value of the "Pareto" slope beta. (c) 2009 Elsevier Ltd. All rights reserved.

  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. Hydrogeology of, simulation of groundwater flow in, and potential effects of sea-level rise on the Kirkwood-Cohansey aquifer system in the vicinity of Edwin B. Forsythe National Wildlife Refuge, New Jersey

    Science.gov (United States)

    Fiore, Alex R.; Voronin, Lois M.; Wieben, Christine M.

    2018-03-19

    The Edwin B. Forsythe National Wildlife Refuge encompasses more than 47,000 acres of New Jersey coastal habitats, including salt marshes, freshwater wetlands, tidal wetlands, barrier beaches, woodlands, and swamps. The refuge is along the Atlantic Flyway and provides breeding habitat for fish, migratory birds, and other wildlife species. The refuge area may be threatened by global climate change, including sea-level rise (SLR).The Kirkwood-Cohansey aquifer system underlies the Edwin B. Forsythe National Wildlife Refuge. Groundwater is an important source of freshwater flow into the refuge, but information about the interaction of surface water and groundwater in the refuge area and the potential effects of SLR on the underlying aquifer system is limited. The U.S. Geological Survey (USGS), in cooperation with the U.S. Fish and Wildlife Service (USFWS), conducted a hydrologic assessment of the refuge in New Jersey and developed a groundwater flow model to improve understanding of the geohydrology of the refuge area and to serve as a tool to evaluate changes in groundwater-level altitudes that may result from a rise in sea level.Groundwater flow simulations completed for this study include a calibrated baseline simulation that represents 2005–15 hydraulic conditions and three SLR scenarios―20, 40, and 60 centimeters (cm) (0.656, 1.312, and 1.968 feet, respectively). Results of the three SLR simulations indicate that the water table in the unconfined Kirkwood-Cohansey aquifer system in the refuge area will rise, resulting in increased discharge of fresh groundwater to freshwater wetlands and streams. As sea level rises, simulated groundwater discharge to the salt marsh, bay, and ocean is projected to decrease. Flow from the salt marsh, bay, and ocean to the overlying surface water is projected to increase as sea level rises.The simulated movement of the freshwater-seawater interface as sea level rises depends on the hydraulic-head gradient. In the center of the

  13. Hydrochemistry, origin and residence time of deep groundwater in the Yuseong area

    International Nuclear Information System (INIS)

    Koh, Yong Kwon; Kim, Geon Young; Bae, Dae Seok; Park, Kyung Woo

    2005-01-01

    As a part of the radioactive waste disposal research program in Korea, the geological, hydrogeological and hydrogeochemical investigations have been carried out in the Yuseong area (KAERI). The temperature or groundwater is measured up to 24 .deg. C and thermal gradient is obtained, to 0.26 .deg. C/100m. pH of groundwater at upper section shows about 7 and the pH of groundwater of 200m below surface reaches almost constant value as 9.9∼10.3. The redox potential of groundwater varied with depth and more negative values were recognized in deep groundwater. The redox potential of deep groundwater, main factor of U solubility, was measured up to -150 mV. These high pH and reduced conditions indicates that the maximum U concentration in groundwater would be limited by the equilibrium solubility of U minerals. The chemistry of shallow groundwater shows Ca-HCO 3 or Ca-Na-HCO 3 type, whereas the deep groundwater belongs to typical Na-HCO 3 type. The chemistry of groundwater below 250m from the surface is constant with depth, indicating that the extent of water-rock reaction is almost unique, which is controlled by the residence time of groundwater. The carbon isotope data (δ 13 C) of groundwater show the contribution of carbon from either that microbial oxidation of organic matter or carbon dioxide from plant respiration. The measurement and interpretation of C-14 indicate that the residence time of borehole deep groundwater ranges from about 2,000 to 6,000 yr BP. The high δ 34 S so4 value of groundwater indicate that the sulfate reduction might be occurred in the deep environment

  14. Integrated groundwater data management

    Science.gov (United States)

    Fitch, Peter; Brodaric, Boyan; Stenson, Matt; Booth, Nathaniel; Jakeman, Anthony J.; Barreteau, Olivier; Hunt, Randall J.; Rinaudo, Jean-Daniel; Ross, Andrew

    2016-01-01

    The goal of a data manager is to ensure that data is safely stored, adequately described, discoverable and easily accessible. However, to keep pace with the evolution of groundwater studies in the last decade, the associated data and data management requirements have changed significantly. In particular, there is a growing recognition that management questions cannot be adequately answered by single discipline studies. This has led a push towards the paradigm of integrated modeling, where diverse parts of the hydrological cycle and its human connections are included. This chapter describes groundwater data management practices, and reviews the current state of the art with enterprise groundwater database management systems. It also includes discussion on commonly used data management models, detailing typical data management lifecycles. We discuss the growing use of web services and open standards such as GWML and WaterML2.0 to exchange groundwater information and knowledge, and the need for national data networks. We also discuss cross-jurisdictional interoperability issues, based on our experience sharing groundwater data across the US/Canadian border. Lastly, we present some future trends relating to groundwater data management.

  15. 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.

  16. List of Accredited Representatives

    Data.gov (United States)

    Department of Veterans Affairs — VA accreditation is for the sole purpose of providing representation services to claimants before VA and does not imply that a representative is qualified to provide...

  17. Numerical analysis of thermal response tests with a groundwater flow and heat transfer model

    Energy Technology Data Exchange (ETDEWEB)

    Raymond, J.; Therrien, R. [Departement de Geologie et de Genie Ggeologique, Universite Laval, 1065 avenue de la medecine, Quebec (Qc) G1V 0A6 (Canada); Gosselin, L. [Departement de Genie Mecanique, Universite Laval, 1065 avenue de la medecine, Quebec (Qc) G1V 0A6 (Canada); Lefebvre, R. [Institut National de la Recherche Scientifique, Centre Eau Terre Environnement, 490 de la Couronne, Quebec (Qc) G1K 9A9 (Canada)

    2011-01-15

    The Kelvin line-source equation, used to analyze thermal response tests, describes conductive heat transfer in a homogeneous medium with a constant temperature at infinite boundaries. The equation is based on assumptions that are valid for most ground-coupled heat pump environments with the exception of geological settings where there is significant groundwater flow, heterogeneous distribution of subsurface properties, a high geothermal gradient or significant atmospheric temperature variations. To address these specific cases, an alternative method to analyze thermal response tests was developed. The method consists in estimating parameters by reproducing the output temperature signal recorded during a test with a numerical groundwater flow and heat transfer model. The input temperature signal is specified at the entrance of the ground heat exchanger, where flow and heat transfer are computed in 2D planes representing piping and whose contributions are added to the 3D porous medium. Results obtained with this method are compared to those of the line-source model for a test performed under standard conditions. A second test conducted in waste rock at the South Dump of the Doyon Mine, where conditions deviate from the line-source assumptions, is analyzed with the numerical model. The numerical model improves the representation of the physical processes involved during a thermal response test compared to the line-source equation, without a significant increase in computational time. (author)

  18. A Bayesian modeling approach for estimation of a shape-free groundwater age distribution using multiple tracers

    NARCIS (Netherlands)

    Massoudieh, A.; Visser, A.; Sharifi, S.; Broers, H.P.

    2014-01-01

    Due to the mixing of groundwaters with different ages in aquifers, groundwater age is more appropriately represented by a distribution rather than a scalar number. To infer a groundwater age distribution from environmental tracers, a mathematical form is often assumed for the shape of the

  19. Impact of excessive groundwater pumping on rejuvenation processes in the Bandung basin (Indonesia) as determined by hydrogeochemistry and modeling

    Science.gov (United States)

    Taufiq, Ahmad; Hosono, Takahiro; Ide, Kiyoshi; Kagabu, Makoto; Iskandar, Irwan; Effendi, Agus J.; Hutasoit, Lambok M.; Shimada, Jun

    2017-12-01

    In the Bandung basin, Indonesia, excessive groundwater pumping caused by rapid increases in industrialization and population growth has caused subsurface environmental problems, such as excessive groundwater drawdown and land subsidence. In this study, multiple hydrogeochemical techniques and numerical modeling have been applied to evaluate the recharge processes and groundwater age (rejuvenation). Although all the groundwater in the Bandung basin is recharged at the same elevation at the periphery of the basin, the water type and residence time of the shallow and deep groundwater could be clearly differentiated. However, there was significant groundwater drawdown in all the depression areas and there is evidence of groundwater mixing between the shallow and deep groundwater. The groundwater mixing was traced from the high dichlorodifluoromethane (CFC-12) concentrations in some deep groundwater samples and by estimating the rejuvenation ratio (R) in some representative observation wells. The magnitude of CFC-12 concentration, as an indicator of young groundwater, showed a good correlation with R, determined using 14C activity in samples taken between 2008 and 2012. These correlations were confirmed with the estimation of vertical downward flux from shallower to deeper aquifers using numerical modeling. Furthermore, the change in vertical flux is affected by the change in groundwater pumping. Since the 1970s, the vertical flux increased significantly and reached approximately 15% of the total pumping amount during the 2000s, as it compensated the groundwater pumping. This study clearly revealed the processes of groundwater impact caused by excessive groundwater pumping using a combination of hydrogeochemical methods and modeling.

  20. Groundwater availability of the Mississippi embayment

    Science.gov (United States)

    Clark, Brian R.; Hart, Rheannon M.; Gurdak, Jason J.

    2011-01-01

    River Valley alluvial aquifer in Arkansas, Louisiana, Mississippi, and Missouri, and to a lesser extent in Illinois, Kentucky, and Tennessee. Predevelopment groundwater flow is represented in the MERAS model as a steady-state stress period, assumed to be prior to 1870. The simulated groundwater-flow budget indicates the largest predevelopment inflow to the system is net recharge to the alluvial aquifer. This inflow is balanced by outflow to gaining streams. Overall, water enters as net recharge to the alluvial aquifer or through outcrop areas of the various hydrogeologic units. Away from the outcrop areas, groundwater flow in the deeper formations is primarily upward into overlying units, ultimately discharging to streams through the alluvial aquifer. Total net recharge and discharge (sum of inflows or outflows) for the model ranged from about 0.66 million acre-feet per year during predevelopment to 20.16 million acre-feet per year by the end of the simulation (final simulated irrigation period in summer of 2006). This change in the model budget reflects increases in withdrawals compared to predevelopment conditions. Cumulative storage within aquifers simulated in the MERAS model indicates overall depletion of 140 million acre-feet (equivalent to 2.8 feet of water covering the entire study area). Postdevelopment inflow to the system is still through net recharge to the alluvial aquifer and the outcrop areas of the several hydrogeologic units, however, the flow between each unit is no longer upward to the alluvial aquifer. Groundwater flow during the summer of 2006 was primarily downward to offset demand from pumping. Early in the model simulation (1870-1920s), the primary components of the water budget were simulated as outflow from stream leakage and inflow from net recharge. As pumpage increased through time, water that would otherwise flow to streams reversed, and net stream leakage became an inflow to the system. The largest reversals began in the mid-1980s, but

  1. Wetting of flat gradient surfaces.

    Science.gov (United States)

    Bormashenko, Edward

    2018-04-01

    Gradient, chemically modified, flat surfaces enable directed transport of droplets. Calculation of apparent contact angles inherent for gradient surfaces is challenging even for atomically flat ones. Wetting of gradient, flat solid surfaces is treated within the variational approach, under which the contact line is free to move along the substrate. Transversality conditions of the variational problem give rise to the generalized Young equation valid for gradient solid surfaces. The apparent (equilibrium) contact angle of a droplet, placed on a gradient surface depends on the radius of the contact line and the values of derivatives of interfacial tensions. The linear approximation of the problem is considered. It is demonstrated that the contact angle hysteresis is inevitable on gradient surfaces. Electrowetting of gradient surfaces is discussed. Copyright © 2018 Elsevier Inc. All rights reserved.

  2. Representing vision and blindness.

    Science.gov (United States)

    Ray, Patrick L; Cox, Alexander P; Jensen, Mark; Allen, Travis; Duncan, William; Diehl, Alexander D

    2016-01-01

    There have been relatively few attempts to represent vision or blindness ontologically. This is unsurprising as the related phenomena of sight and blindness are difficult to represent ontologically for a variety of reasons. Blindness has escaped ontological capture at least in part because: blindness or the employment of the term 'blindness' seems to vary from context to context, blindness can present in a myriad of types and degrees, and there is no precedent for representing complex phenomena such as blindness. We explore current attempts to represent vision or blindness, and show how these attempts fail at representing subtypes of blindness (viz., color blindness, flash blindness, and inattentional blindness). We examine the results found through a review of current attempts and identify where they have failed. By analyzing our test cases of different types of blindness along with the strengths and weaknesses of previous attempts, we have identified the general features of blindness and vision. We propose an ontological solution to represent vision and blindness, which capitalizes on resources afforded to one who utilizes the Basic Formal Ontology as an upper-level ontology. The solution we propose here involves specifying the trigger conditions of a disposition as well as the processes that realize that disposition. Once these are specified we can characterize vision as a function that is realized by certain (in this case) biological processes under a range of triggering conditions. When the range of conditions under which the processes can be realized are reduced beyond a certain threshold, we are able to say that blindness is present. We characterize vision as a function that is realized as a seeing process and blindness as a reduction in the conditions under which the sight function is realized. This solution is desirable because it leverages current features of a major upper-level ontology, accurately captures the phenomenon of blindness, and can be

  3. 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

  4. 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

  5. Hydrodynamic analysis application of contaminated groundwater remediation to oil hydrocarbons

    OpenAIRE

    Pajić Predrag R.; Čalenić Aleksandar I.; Polomčić Dušan M.; Bajić Dragoljub I.

    2017-01-01

    In this paper, the application of the hydrodynamic analysis in the selected ‘pumping and treatment’ remediation method of groundwater hydrocarbon pollution in the case of the Pancevo oil refinery is examined. The applied hydrodynamic analysis represents a regular and necessary approach in modern hydrogeology. Previous chemical analysis of soil and groundwater samples at observation objects revealed their pollution by oil products. New researches included the constraction of 12 piezometric bor...

  6. Natural radioactivity in groundwater sources in Ireland

    Energy Technology Data Exchange (ETDEWEB)

    Currivan, L.; Dowdall, A.; Mcginnity, P.; Ciara, M. [Radiological Protection Institute of Ireland (Ireland); Craig, M. [Environmental Protection Agency (Ireland)

    2014-07-01

    The Radiological Protection Institute of Ireland (RPII) in collaboration with the Irish Environmental Protection Agency (EPA) undertook a national survey of radioactivity in groundwater sources for compliance with parameters set out in the European Communities Drinking Water Directive. The Directive outlines the minimum requirements for the quality of drinking water and water intended for human consumption. Over two hundred samples were screened for radioactivity. Where indicated, analysis for individual radionuclide activity was undertaken and the radiation dose arising calculated. Furthermore, samples were analysed for radon concentration. This survey is the first comprehensive national survey of radioactivity in groundwater sources in Ireland. Approximately 18 per cent of drinking water in Ireland originates from groundwater and springs with the remainder from surface water. Between 2007 and 2011, water samples from a representative network of groundwater sources were analysed and assessed for compliance with the radioactivity parameters set out in the Drinking Water Directive. The assessment was carried out using the methodology for screening drinking water set out by the WHO. For practical purposes the WHO recommended screening levels for drinking water below which no further action is required of 100 mBq/l for gross alpha activity and 1000 mBq/l for gross beta activity were applied. Of the 203 groundwater sources screened for gross alpha and gross beta all met the gross beta activity criteria of less than 1000 mBq/l and 175 supplies had gross alpha activity concentrations of less than 100 mBq/l. For these sources no further analysis was required. The remaining 28 sources required further (radionuclide-specific) analysis from an alpha activity perspective. Results on ranges and distributions of radionuclide concentrations in groundwater as well as ingestion doses estimated for consumers of these water supplies will be presented. Document available in abstract

  7. 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

  8. Controlling groundwater pumping online.

    Science.gov (United States)

    Zekri, Slim

    2009-08-01

    Groundwater over-pumping is a major problem in several countries around the globe. Since controlling groundwater pumping through water flow meters is hardly feasible, the surrogate is to control electricity usage. This paper presents a framework to restrict groundwater pumping by implementing an annual individual electricity quota without interfering with the electricity pricing policy. The system could be monitored online through prepaid electricity meters. This provides low transaction costs of individual monitoring of users compared to the prohibitive costs of water flow metering and monitoring. The public groundwater managers' intervention is thus required to determine the water and electricity quota and watch the electricity use online. The proposed framework opens the door to the establishment of formal groundwater markets among users at very low transaction costs. A cost-benefit analysis over a 25-year period is used to evaluate the cost of non-action and compare it to the prepaid electricity quota framework in the Batinah coastal area of Oman. Results show that the damage cost to the community, if no active policy is implemented, amounts to (-$288) million. On the other hand, the implementation of a prepaid electricity quota with an online management system would result in a net present benefit of $199 million.

  9. 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

  10. Gamma radiolysis effects on basalt groundwater

    International Nuclear Information System (INIS)

    Gray, W.J.

    1983-10-01

    Gamma radiolysis of basalt groundwater containing 700 ppM methane produces a milky liquid that is a suspension of fine particles of a high molecular weight hydrocarbon somewhat like polyethylene. The ability of these polymers to chelate with, or otherwise sorb, metal ions from aqueous solution was measured using Cu +2 as a representative cation. Values in the range 0.3 to 0.8 millimoles of Cu per liter of solution were found. 5 references, 2 figures, 2 tables

  11. 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

  12. 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

  13. Belgrade waterworks groundwater source

    International Nuclear Information System (INIS)

    Sotic, A.; Dasic, M.; Vukcevic, G.; Vasiljevic, Lj.; Nikolic, S.

    2002-01-01

    Paper deals with Belgrade Waterworks groundwater source, its characteristics, conception of protection programme, contaminations on source and with parameters of groundwater quality degradation. Groundwaters present natural heritage with their strategic and slow renewable natural resources attributes, and as such they require priority in protection. It is of greatest need that existing source is to be protected and used optimally for producing quality drinkable water. The concept of source protection programme should be based on regular water quality monitoring, identification of contaminators, defining areas of their influences on the source and their permanent control. However, in the last 10 years, but drastically in the last 3, because of the overall situation in the country, it is very characteristic downfall in volume of business, organisation and the level of supply of the technical equipment

  14. Basin F Subregional Groundwater Model

    National Research Council Canada - National Science Library

    Mazion, Edward

    2001-01-01

    The groundwater flow system at Rocky Mountain Arsenal (RMA) is complex. To evaluate proposed remedial alternatives, interaction of the local groundwater flow system with the present contamination control systems must be understood...

  15. Groundwater characterisation and modelling: problems, facts and possibilities

    Energy Technology Data Exchange (ETDEWEB)

    Laaksoharju, Marcus [INTERA KB, Sollentuna (Sweden)

    1999-12-01

    For the last 10 years, the Aespoe Hard Rock Laboratory (HRL) in Sweden has been the main test site for the development of suitable methods for the final disposal of spent nuclear fuel. Major achievements have been made in the development of new groundwater sampling and modelling techniques. The natural condition of the groundwater is easily disturbed by drilling and sampling. The effects from borehole activities which may bias the real character of the groundwater have been identified. The development of new sampling techniques has improved the representativeness of the groundwater samples. In addition, methods to judge the representativeness better have been developed. For modelling of the Aespoe site, standard groundwater modelling codes based on thermodynamic laws have been applied. The many limitations of existing geochemical models used at the Aespoe site and the need to decode the complex groundwater information in terms of origin, mixing and reactions at site scale necessitated the development of a new modelling tool. This new modelling concept was named M3. In M3 modelling the assumption is that the groundwater chemistry is a result of mixing as well as water/rock reactions. The M3 model compares the groundwater compositions from a site. The similarities and differences of the groundwater compositions are used to quantify the contribution from mixing and reactions on the measured data. In order to construct a reliable model the major components, stable isotopes and tritium are used. Initially, the method quantifies the contribution from the flow system. Subsequently, contributions from reactions are calculated. The model differs from many other standard models which primarily use reactions rather than mixing to determine the groundwater evolution. The M3 code has been used for the following type of modelling: calculate the mixing portions at Aespoe, quantify the contribution from inorganic and organic reactions such as biogenic decomposition and sulphate

  16. Representing Color Ensembles.

    Science.gov (United States)

    Chetverikov, Andrey; Campana, Gianluca; Kristjánsson, Árni

    2017-10-01

    Colors are rarely uniform, yet little is known about how people represent color distributions. We introduce a new method for studying color ensembles based on intertrial learning in visual search. Participants looked for an oddly colored diamond among diamonds with colors taken from either uniform or Gaussian color distributions. On test trials, the targets had various distances in feature space from the mean of the preceding distractor color distribution. Targets on test trials therefore served as probes into probabilistic representations of distractor colors. Test-trial response times revealed a striking similarity between the physical distribution of colors and their internal representations. The results demonstrate that the visual system represents color ensembles in a more detailed way than previously thought, coding not only mean and variance but, most surprisingly, the actual shape (uniform or Gaussian) of the distribution of colors in the environment.

  17. Technical framework for groundwater restoration

    International Nuclear Information System (INIS)

    1991-04-01

    This document provides the technical framework for groundwater restoration under Phase II of the Uranium Mill Tailings Remedial Action (UMTRA) Project. A preliminary management plan for Phase II has been set forth in a companion document titled ''Preplanning Guidance Document for Groundwater Restoration''. General principles of site characterization for groundwater restoration, restoration methods, and treatment are discussed in this document to provide an overview of standard technical approaches to groundwater restoration

  18. In situ groundwater bioremediation

    Energy Technology Data Exchange (ETDEWEB)

    Hazen, Terry C.

    2009-02-01

    In situ groundwater bioremediation of hydrocarbons has been used for more than 40 years. Most strategies involve biostimulation; however, recently bioaugmentation have been used for dehalorespiration. Aquifer and contaminant profiles are critical to determining the feasibility and strategy for in situ groundwater bioremediation. Hydraulic conductivity and redox conditions, including concentrations of terminal electron acceptors are critical to determine the feasibility and strategy for potential bioremediation applications. Conceptual models followed by characterization and subsequent numerical models are critical for efficient and cost effective bioremediation. Critical research needs in this area include better modeling and integration of remediation strategies with natural attenuation.

  19. Mimicking natural cell environments: design, fabrication and application of bio-chemical gradients on polymeric biomaterial substrates

    NARCIS (Netherlands)

    Benetti, Edmondo Maria; Klein Gunnewiek, Michel; van Blitterswijk, Clemens; Vancso, Gyula J.; Moroni, Lorenzo

    2016-01-01

    Gradients of biomolecules on synthetic, solid substrates can efficiently mimic the natural, graded variation of properties of the extracellular matrix (ECM). Such gradients represent accessible study platforms for the understanding of cellular activities, and they also provide functional supports

  20. Fully integrated physically-based numerical modelling of impacts of groundwater extraction on surface and irrigation-induced groundwater interactions: case study Lower River Murray, Australia

    Science.gov (United States)

    Alaghmand, S.; Beecham, S.; Hassanli, A.

    2013-07-01

    Combination of reduction in the frequency, duration and magnitude of natural floods, rising saline water-table in floodplains and excessive evapotranspiration have led to an irrigation-induced groundwater mound forced the naturally saline groundwater onto the floodplain in the Lower River Murray. It is during the attenuation phase of floods that these large salt accumulations are likely to be mobilised and will discharge into the river. The Independent Audit Group for Salinity highlighted this as the most significant risk in the Murray-Darling Basin. South Australian government and catchment management authorities have developed salt interception schemes (SIS). This is to pump the highly saline groundwater from the floodplain aquifer to evaporation basins in order to reduce the hydraulic gradient that drives the regional saline groundwater towards the River Murray. This paper investigates the interactions between a river (River Murray in South Australia) and a saline semi-arid floodplain (Clarks Floodplain) significantly influenced by groundwater lowering (Bookpurnong SIS). Results confirm that groundwater extraction maintain a lower water-table and more fresh river water flux to the saline floodplain aquifer. In term of salinity, this may lead to less amount of solute stored in the floodplain aquifer. This occurs through two mechanisms; extracting some of the solute mass from the system and changing the floodplain groundwater regime from a losing to gaining one. Finally, it is shown that groundwater extraction is able to remove some amount of solute stored in the unsaturated zone and mitigate the floodplain salinity risk.

  1. Resolving terrestrial ecosystem processes along a subgrid topographic gradient for an earth-system model

    Science.gov (United States)

    Subin, Z M; Milly, Paul C.D.; Sulman, B N; Malyshev, Sergey; Shevliakova, E

    2014-01-01

    Soil moisture is a crucial control on surface water and energy fluxes, vegetation, and soil carbon cycling. Earth-system models (ESMs) generally represent an areal-average soil-moisture state in gridcells at scales of 50–200 km and as a result are not able to capture the nonlinear effects of topographically-controlled subgrid heterogeneity in soil moisture, in particular where wetlands are present. We addressed this deficiency by building a subgrid representation of hillslope-scale topographic gradients, TiHy (Tiled-hillslope Hydrology), into the Geophysical Fluid Dynamics Laboratory (GFDL) land model (LM3). LM3-TiHy models one or more representative hillslope geometries for each gridcell by discretizing them into land model tiles hydrologically coupled along an upland-to-lowland gradient. Each tile has its own surface fluxes, vegetation, and vertically-resolved state variables for soil physics and biogeochemistry. LM3-TiHy simulates a gradient in soil moisture and water-table depth between uplands and lowlands in each gridcell. Three hillslope hydrological regimes appear in non-permafrost regions in the model: wet and poorly-drained, wet and well-drained, and dry; with large, small, and zero wetland area predicted, respectively. Compared to the untiled LM3 in stand-alone experiments, LM3-TiHy simulates similar surface energy and water fluxes in the gridcell-mean. However, in marginally wet regions around the globe, LM3-TiHy simulates shallow groundwater in lowlands, leading to higher evapotranspiration, lower surface temperature, and higher leaf area compared to uplands in the same gridcells. Moreover, more than four-fold larger soil carbon concentrations are simulated globally in lowlands as compared with uplands. We compared water-table depths to those simulated by a recent global model-observational synthesis, and we compared wetland and inundated areas diagnosed from the model to observational datasets. The comparisons demonstrate that LM3-TiHy has the

  2. Comparative studies of groundwater vulnerability assessment

    Science.gov (United States)

    Maria, Rizka

    2018-02-01

    Pollution of groundwater is a primary issue because aquifers are susceptible to contamination from land use and anthropogenic impacts. Groundwater susceptibility is intrinsic and specific. Intrinsic vulnerability refers to an aquifer that is susceptible to pollution and to the geological and hydrogeological features. Vulnerability assessment is an essential step in assessing groundwater contamination. This approach provides a visual analysis for helping planners and decision makers to achieve the sustainable management of water resources. Comparative studies are applying different methodologies to result in the basic evaluation of the groundwater vulnerability. Based on the comparison of methods, there are several advantages and disadvantages. SI can be overlaid on DRASTIC and Pesticide DRASTIC to extract the divergence in sensitivity. DRASTIC identifies low susceptibility and underestimates the pollution risk while Pesticide DRASTIC and SI represents better risk and is recommended for the future. SINTACS method generates very high vulnerability zones with surface waters and aquifer interactions. GOD method could be adequate for vulnerability mapping in karstified carbonate aquifers at small-moderate scales, and EPIK method can be used for large scale. GOD method is suitable for designing large area such as land management while DRASTIC has good accuracy and more real use in geoenvironmental detailed studies.

  3. Gradient Boosting Machines, A Tutorial

    Directory of Open Access Journals (Sweden)

    Alexey eNatekin

    2013-12-01

    Full Text Available Gradient boosting machines are a family of powerful machine-learning techniques that have shown considerable success in a wide range of practical applications. They are highly customizable to the particular needs of the application, like being learned with respect to different loss functions. This article gives a tutorial introduction into the methodology of gradient boosting methods. A theoretical information is complemented with many descriptive examples and illustrations which cover all the stages of the gradient boosting model design. Considerations on handling the model complexity are discussed. A set of practical examples of gradient boosting applications are presented and comprehensively analyzed.

  4. An extended discrete gradient formula for oscillatory Hamiltonian systems

    International Nuclear Information System (INIS)

    Liu Kai; Shi Wei; Wu Xinyuan

    2013-01-01

    In this paper, incorporating the idea of the discrete gradient method into the extended Runge–Kutta–Nyström integrator, we derive and analyze an extended discrete gradient formula for the oscillatory Hamiltonian system with the Hamiltonian H(p,q)= 1/2 p T p+ 1/2 q T Mq+U(q), where q:R→R d represents generalized positions, p:R→R d represents generalized momenta and M is an element of R dxd is a symmetric and positive semi-definite matrix. The solution of this system is a nonlinear oscillator. Basically, many nonlinear oscillatory mechanical systems with a partitioned Hamiltonian function lend themselves to this approach. The extended discrete gradient formula presented in this paper exactly preserves the energy H(p, q). We derive some properties of the new formula. The convergence is analyzed for the implicit schemes based on the discrete gradient formula, and it turns out that the convergence of the implicit schemes based on the extended discrete gradient formula is independent of ‖M‖, which is a significant property for the oscillatory Hamiltonian system. Thus, it transpires that a larger step size can be chosen for the new energy-preserving schemes than that for the traditional discrete gradient methods when applied to the oscillatory Hamiltonian system. Illustrative examples show the competence and efficiency of the new schemes in comparison with the traditional discrete gradient methods in the scientific literature. (paper)

  5. OSMOSE experiment representativity studies.

    Energy Technology Data Exchange (ETDEWEB)

    Aliberti, G.; Klann, R.; Nuclear Engineering Division

    2007-10-10

    The OSMOSE program aims at improving the neutronic predictions of advanced nuclear fuels through measurements in the MINERVE facility at the CEA-Cadarache (France) on samples containing the following separated actinides: Th-232, U-233, U-234, U-235, U-236, U-238, Np-237, Pu-238, Pu-239, Pu-240, Pu-241, Pu-242, Am-241, Am-243, Cm-244 and Cm-245. The goal of the experimental measurements is to produce a database of reactivity-worth measurements in different neutron spectra for the separated heavy nuclides. This database can then be used as a benchmark for integral reactivity-worth measurements to verify and validate reactor analysis codes and integral cross-section values for the isotopes tested. In particular, the OSMOSE experimental program will produce very accurate sample reactivity-worth measurements for a series of actinides in various spectra, from very thermalized to very fast. The objective of the analytical program is to make use of the experimental data to establish deficiencies in the basic nuclear data libraries, identify their origins, and provide guidelines for nuclear data improvements in coordination with international programs. To achieve the proposed goals, seven different neutron spectra can be created in the MINERVE facility: UO2 dissolved in water (representative of over-moderated LWR systems), UO2 matrix in water (representative of LWRs), a mixed oxide fuel matrix, two thermal spectra containing large epithermal components (representative of under-moderated reactors), a moderated fast spectrum (representative of fast reactors which have some slowing down in moderators such as lead-bismuth or sodium), and a very hard spectrum (representative of fast reactors with little moderation from reactor coolant). The different spectra are achieved by changing the experimental lattice within the MINERVE reactor. The experimental lattice is the replaceable central part of MINERVE, which establishes the spectrum at the sample location. This configuration

  6. Representing distance, consuming distance

    DEFF Research Database (Denmark)

    Larsen, Gunvor Riber

    Title: Representing Distance, Consuming Distance Abstract: Distance is a condition for corporeal and virtual mobilities, for desired and actual travel, but yet it has received relatively little attention as a theoretical entity in its own right. Understandings of and assumptions about distance...... are being consumed in the contemporary society, in the same way as places, media, cultures and status are being consumed (Urry 1995, Featherstone 2007). An exploration of distance and its representations through contemporary consumption theory could expose what role distance plays in forming...

  7. Gradient waveform synthesis for magnetic propulsion using MRI gradient coils

    International Nuclear Information System (INIS)

    Han, B H; Lee, S Y; Park, S

    2008-01-01

    Navigating an untethered micro device in a living subject is of great interest for both diagnostic and therapeutic applications. Magnetic propulsion of an untethered device carrying a magnetic core in it is one of the promising methods to navigate the device. MRI gradients coils are thought to be suitable for navigating the device since they are capable of magnetic propulsion in any direction while providing magnetic resonance images. For precise navigation of the device, especially in the peripheral region of the gradient coils, the concomitant gradient fields, as well as the linear gradient fields in the main magnetic field direction, should be considered in driving the gradient coils. For simple gradient coil configurations, the Maxwell coil in the z-direction and the Golay coil in the x- and y-directions, we have calculated the magnetic force fields, which are not necessarily the same as the conventional linear gradient fields of MRI. Using the calculated magnetic force fields, we have synthesized gradient waveforms to navigate the device along a desired path

  8. Groundwater-surface water interaction

    International Nuclear Information System (INIS)

    White, P.A.; Clausen, B.; Hunt, B.; Cameron, S.; Weir, J.J.

    2001-01-01

    This chapter discusses natural and modified interactions between groundwater and surface water. Theory on recharge to groundwater from rivers is introduced, and the relative importance of groundwater recharge from rivers is illustrated with an example from the Ngaruroro River, Hawke's Bay. Some of the techniques used to identify and measure recharge to groundwater from gravel-bed rivers will be outlined, with examples from the Ngaruroro River, where the recharge reach is relatively well defined, and from the Rakaia River, where it is poorly defined. Groundwater recharged from rivers can have characteristic chemical and isotopic signatures, as shown by Waimakariri River water in the Christchurch-West Melton groundwater system. The incorporation of groundwater-river interaction in a regional groundwater flow model is outlined for the Waimea Plains, and relationships between river scour and groundwater recharge are examined for the Waimakariri River. Springs are the result of natural discharge from groundwater systems and are important water sources. The interactions between groundwater systems, springs, and river flow for the Avon River in New Zealand will be outlined. The theory of depletion of stream flow by groundwater pumpage will be introduced with a case study from Canterbury, and salt-water intrusion into groundwater systems with examples from Nelson and Christchurch. The theory of artificial recharge to groundwater systems is introduced with a case study from Hawke's Bay. Wetlands are important to flora, and the relationship of the wetland environment to groundwater hydrology will be discussed, with an example from the South Taupo wetland. (author). 56 refs., 25 figs., 3 tabs

  9. Optimizing sampling approaches along ecological gradients

    DEFF Research Database (Denmark)

    Schweiger, Andreas; Irl, Severin D. H.; Steinbauer, Manuel

    2016-01-01

    1. Natural scientists and especially ecologists use manipulative experiments or field observations along gradients to differentiate patterns driven by processes from those caused by random noise. A well-conceived sampling design is essential for identifying, analysing and reporting underlying...... patterns in a statistically solid and reproducible manner, given the normal restrictions in labour, time and money. However, a technical guideline about an adequate sampling design to maximize prediction success under restricted resources is lacking. This study aims at developing such a solid...... and reproducible guideline for sampling along gradients in all fields of ecology and science in general. 2. We conducted simulations with artificial data for five common response types known in ecology, each represented by a simple function (no response, linear, exponential, symmetric unimodal and asymmetric...

  10. Scattering-angle based filtering of the waveform inversion gradients

    KAUST Repository

    Alkhalifah, Tariq Ali

    2014-01-01

    Full waveform inversion (FWI) requires a hierarchical approach to maneuver the complex non-linearity associated with the problem of velocity update. In anisotropic media, the non-linearity becomes far more complex with the potential trade-off between the multiparameter description of the model. A gradient filter helps us in accessing the parts of the gradient that are suitable to combat the potential non-linearity and parameter trade-off. The filter is based on representing the gradient in the time-lag normalized domain, in which the low scattering angle of the gradient update is initially muted out in the FWI implementation, in what we may refer to as a scattering angle continuation process. The result is a low wavelength update dominated by the transmission part of the update gradient. In this case, even 10 Hz data can produce vertically near-zero wavenumber updates suitable for a background correction of the model. Relaxing the filtering at a later stage in the FWI implementation allows for smaller scattering angles to contribute higher-resolution information to the model. The benefits of the extended domain based filtering of the gradient is not only it's ability in providing low wavenumber gradients guided by the scattering angle, but also in its potential to provide gradients free of unphysical energy that may correspond to unrealistic scattering angles.

  11. Scattering-angle based filtering of the waveform inversion gradients

    KAUST Repository

    Alkhalifah, Tariq Ali

    2014-11-22

    Full waveform inversion (FWI) requires a hierarchical approach to maneuver the complex non-linearity associated with the problem of velocity update. In anisotropic media, the non-linearity becomes far more complex with the potential trade-off between the multiparameter description of the model. A gradient filter helps us in accessing the parts of the gradient that are suitable to combat the potential non-linearity and parameter trade-off. The filter is based on representing the gradient in the time-lag normalized domain, in which the low scattering angle of the gradient update is initially muted out in the FWI implementation, in what we may refer to as a scattering angle continuation process. The result is a low wavelength update dominated by the transmission part of the update gradient. In this case, even 10 Hz data can produce vertically near-zero wavenumber updates suitable for a background correction of the model. Relaxing the filtering at a later stage in the FWI implementation allows for smaller scattering angles to contribute higher-resolution information to the model. The benefits of the extended domain based filtering of the gradient is not only it\\'s ability in providing low wavenumber gradients guided by the scattering angle, but also in its potential to provide gradients free of unphysical energy that may correspond to unrealistic scattering angles.

  12. PATHS groundwater hydrologic model

    Energy Technology Data Exchange (ETDEWEB)

    Nelson, R.W.; Schur, J.A.

    1980-04-01

    A preliminary evaluation capability for two-dimensional groundwater pollution problems was developed as part of the Transport Modeling Task for the Waste Isolation Safety Assessment Program (WISAP). Our approach was to use the data limitations as a guide in setting the level of modeling detail. PATHS Groundwater Hydrologic Model is the first level (simplest) idealized hybrid analytical/numerical model for two-dimensional, saturated groundwater flow and single component transport; homogeneous geology. This document consists of the description of the PATHS groundwater hydrologic model. The preliminary evaluation capability prepared for WISAP, including the enhancements that were made because of the authors' experience using the earlier capability is described. Appendixes A through D supplement the report as follows: complete derivations of the background equations are provided in Appendix A. Appendix B is a comprehensive set of instructions for users of PATHS. It is written for users who have little or no experience with computers. Appendix C is for the programmer. It contains information on how input parameters are passed between programs in the system. It also contains program listings and test case listing. Appendix D is a definition of terms.

  13. Automated Groundwater Screening

    International Nuclear Information System (INIS)

    Taylor, Glenn A.; Collard, Leonard B.

    2005-01-01

    The Automated Intruder Analysis has been extended to include an Automated Ground Water Screening option. This option screens 825 radionuclides while rigorously applying the National Council on Radiation Protection (NCRP) methodology. An extension to that methodology is presented to give a more realistic screening factor for those radionuclides which have significant daughters. The extension has the promise of reducing the number of radionuclides which must be tracked by the customer. By combining the Automated Intruder Analysis with the Automated Groundwater Screening a consistent set of assumptions and databases is used. A method is proposed to eliminate trigger values by performing rigorous calculation of the screening factor thereby reducing the number of radionuclides sent to further analysis. Using the same problem definitions as in previous groundwater screenings, the automated groundwater screening found one additional nuclide, Ge-68, which failed the screening. It also found that 18 of the 57 radionuclides contained in NCRP Table 3.1 failed the screening. This report describes the automated groundwater screening computer application

  14. Controlling groundwater over abstraction

    NARCIS (Netherlands)

    Naber, Al Majd; Molle, Francois

    2017-01-01

    The control of groundwater over abstraction is a vexing problem worldwide. Jordan is one of the countries facing severe water scarcity which has implemented a wide range of measures and policies over the past 20 years. While the gap between formal legal and policy frameworks and local practices on

  15. 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

  16. Groundwater quota versus tiered groundwater pricing : two cases of groundwater management in north-west China

    NARCIS (Netherlands)

    Aarnoudse, Eefje; Qu, Wei; Bluemling, B.; Herzfeld, Thomas

    2017-01-01

    Difficulties in monitoring groundwater extraction cause groundwater regulations to fail worldwide. In two counties in north-west China local water authorities have installed smart card machines to monitor and regulate farmers’ groundwater use. Data from a household survey and in-depth interviews are

  17. Simulation by a mathematical model of the groundwater flow between the Alps and the Black Forest; Part A: regional model; Part B: local model (Northern Switzerland)

    International Nuclear Information System (INIS)

    Kimmeier, F.; Perrochet, P.; Kiraly, L.

    1985-01-01

    The purpose of this report is to present the development of two hydrogeologic models of the groundwater flow regime in the crystalline of northern Switzerland. These models are constructed at two scales. The regional model (23000 km 2 ) accounts for all recharge to and discharge from the crystalline within the model boundaries. The local model (900 km 2 ) allows for greater structural, stratigraphic and topographic complexity in a more restricted area including some of the areas of interest to CEDRA. The regional model provides the hydrologic boundary conditions for the local model. All steps followed in constructing and testing the models are presented. This includes defining the areal and vertical geometry of the principal aquifers and aquitards. In addition, the hydrogeologic properties of these layers are defined; including their permeability, homogeneity, anisotropy and continuity. Discontinuities (e.g. faults) are modeled as discrete features. Hydrologic boundary conditions are specified based on observed or inferred potentiometric or flow (infiltration/exfiltration) data. The developed conceptual models are tested with program FEM 301. The results of this application consist of heads at every noidal point and recharge/discharge rates at every constant head node. These results are utilized to define the general groundwater flow regimes in the crystalline. In addition, the results are compared to observed heads and discharges in an attempt to validate the conceptual models. Representative hydraulic gradients at potential areas of interest to CEDRA are presented. Sensitivity analyses have been conducted to define the groundwater flow systems response to uncertain parameters and boundary conditions

  18. HANFORD GROUNDWATER REMEDIATION

    Energy Technology Data Exchange (ETDEWEB)

    CHARBONEAU, B; THOMPSON, M; WILDE, R.; FORD, B.; GERBER, M.S.

    2006-02-01

    By 1990 nearly 50 years of producing plutonium put approximately 1.70E + 12 liters (450 billion gallons) of liquid wastes into the soil of the 1,518-square kilometer (586-square mile) Hanford Site in southeast Washington State. The liquid releases consisted of chemicals used in laboratory experiments, manufacturing and rinsing uranium fuel, dissolving that fuel after irradiation in Hanford's nuclear reactors, and in liquefying plutonium scraps needed to feed other plutonium-processing operations. Chemicals were also added to the water used to cool Hanford's reactors to prevent corrosion in the reactor tubes. In addition, water and acid rinses were used to clean plutonium deposits from piping in Hanford's large radiochemical facilities. All of these chemicals became contaminated with radionuclides. As Hanford raced to help win World War II, and then raced to produce materials for the Cold War, these radioactive liquid wastes were released to the Site's sandy soils. Early scientific experiments seemed to show that the most highly radioactive components of these liquids would bind to the soil just below the surface of the land, thus posing no threat to groundwater. Other experiments predicted that the water containing most radionuclides would take hundreds of years to seep into groundwater, decaying (or losing) most of its radioactivity before reaching the groundwater or subsequently flowing into the Columbia River, although it was known that some contaminants like tritium would move quickly. Evidence today, however, shows that many contaminants have reached the Site's groundwater and the Columbia River, with more on its way. Over 259 square kilometers (100 square miles) of groundwater at Hanford have contaminant levels above drinking-water standards. Also key to successfully cleaning up the Site is providing information resources and public-involvement opportunities to Hanford's stakeholders. This large, passionate, diverse, and

  19. Radon as a groundwater tracer in Forsmark and Laxemar

    International Nuclear Information System (INIS)

    Grolander, Sara

    2009-10-01

    caused by the homogenous radon concentrations measured in the Laxemar area. The radon concentrations in near surface water measured in Forsmark showed large variability with both low and high radon concentrations. This large variability in radon concentration could not be explained by the flow pattern of the groundwater since no clear correlation between radon concentration and recharge/discharge classification was found. The radon concentration was also measured at different depths in the soil profile at three locations in the Forsmark area. The results showed large differences with increasing radon concentration with increasing depth. This gradient of radon concentration can be explained largely by the radon emanation potential of the local soil type at different depths. High radon concentrations were found in wells with higher radon emanation potential like till and bedrock. These observations showed the importance of the radon emanation potential of the local soil for the radon concentration in groundwater. The main purpose of this study has been to evaluate the use of radon as a tracer for groundwater flow patterns. The method is based on the ingrowth of radon from its progenitor radium according to the law of radioactive decay. According to this law the radon concentration in groundwater will reach equilibrium conditions after approximately 30 days in contact with the surrounding soil. The equilibrium radon concentration of the near surface groundwater was measured at several location in the Forsmark area and a range of the steady state radon concentration was calculated. The measured steady state radon concentration was then used to evaluate the radon concentrations measured in near surface groundwater in the area. A recharge/discharge classification of the wells was done based on the range of steady state radon concentration and the measured radon concentrations in groundwater. All wells with radon concentration below the steady state radon concentration were

  20. Black Swans and the Effectiveness of Remediating Groundwater Contamination

    Science.gov (United States)

    Siegel, D. I.; Otz, M. H.; Otz, I.

    2013-12-01

    Black swans, outliers, dominate science far more than do predictable outcomes. Predictable success constitutes the Black Swan in groundwater remediation. Even the National Research Council concluded that remediating groundwater to drinking water standards has failed in typically complex hydrogeologic settings where heterogeneities and preferential flow paths deflect flow paths obliquely to hydraulic gradients. Natural systems, be they biological or physical, build upon a combination of large-scale regularity coupled to chaos at smaller scales. We show through a review of over 25 case studies that groundwater remediation efforts are best served by coupling parsimonious site characterization to natural and induced geochemical tracer tests to at least know where contamination advects with groundwater in the subsurface. In the majority of our case studies, actual flow paths diverge tens of degrees from anticipated flow paths because of unrecognized heterogeneities in the horizontal direction of transport, let alone the vertical direction. Consequently, regulatory agencies would better serve both the public and the environment by recognizing that long-term groundwater cleanup probably is futile in most hydrogeologic settings except to relaxed standards similar to brownfielding. A Black Swan

  1. Denaturing gradient gel electrophoresis

    International Nuclear Information System (INIS)

    Kocherginskaya, S.A.; Cann, I.K.O.; Mackie, R.I.

    2005-01-01

    It is worthwhile considering that only some 30 species make up the bulk of the bacterial population in human faeces at any one time based on the classical cultivation-based approach. The situation in the rumen is similar. Thus, it is practical to focus on specific groups of interest within the complex community. These may be the predominant or the most active species, specific physiological groups or readily identifiable (genetic) clusters of phylogenetically related organisms. Several 16S rDNA fingerprinting techniques can be invaluable for selecting and monitoring sequences or phylogenetic groups of interest and are described below. Over the past few decades, considerable attention was focussed on the identification of pure cultures of microbes on the basis of genetic polymorphisms of DNA encoding rRNA such as ribotyping, amplified fragment length polymorphism and randomly amplified polymorphic DNA. However, many of these methods require prior cultivation and are less suitable for use in analysis of complex mixed populations although important in describing cultivated microbial diversity in molecular terms. Much less attention was given to molecular characterization of complex communities. In particular, research into diversity and community structure over time has been revolutionized by the advent of molecular fingerprinting techniques for complex communities. Denaturing or temperature gradient gel electrophoresis (DGGE/TGGE) methods have been successfully applied to the analysis of human, pig, cattle, dog and rodent intestinal populations

  2. Ion temperature gradient instability

    International Nuclear Information System (INIS)

    1989-01-01

    Anomalous ion thermal conductivity remains an open physics issue for the present generation of high temperature Tokamaks. It is generally believed to be due to Ion Temperature Gradient Instability (η i mode). However, it has been difficult, if not impossible to identify this instability and study the anomalous transport due to it, directly. Therefore the production and identification of the mode is pursued in the simpler and experimentally convenient configuration of the Columbia Linear Machine (CLM). CLM is a steady state machine which already has all the appropriate parameters, except η i . This parameter is being increased to the appropriate value of the order of 1 by 'feathering' a tungsten screen located between the plasma source and the experimental cell to flatten the density profile and appropriate redesign of heating antennas to steepen the ion temperature profile. Once the instability is produced and identified, a thorough study of the characteristics of the mode can be done via a wide range of variation of all the critical parameters: η i , parallel wavelength, etc

  3. Assessment of agricultural groundwater users in Iran: a cultural environmental bias

    Science.gov (United States)

    Salehi, Saeid; Chizari, Mohammad; Sadighi, Hassan; Bijani, Masoud

    2018-02-01

    Many environmental problems are rooted in human behavior. This study aimed to explore the causal effect of cultural environmental bias on `sustainable behavior' among agricultural groundwater users in Fars province, Iran, according to Klockner's comprehensive model. A survey-based research project was conducted to gathering data on the paradigm of environmental psychology. The sample included agricultural groundwater users ( n = 296) who were selected at random within a structured sampling regime involving study areas that represent three (higher, medium and lower) bounds of the agricultural-groundwater-vulnerability spectrum. Results showed that the "environment as ductile (EnAD)" variable was a strong determinant of sustainable behavior as it related to groundwater use, and that EnAE had the highest causal effect on the behavior of agricultural groundwater users. The adjusted model explained 41% variance of "groundwater sustainable behavior". Based on the results, the groundwater sustainable behaviors of agricultural groundwater users were found to be affected by personal and subjective norm variables and that they are influenced by casual effects of the "environment as ductile (EnAD)" variable. The conclusions reflect the Fars agricultural groundwater users' attitude or worldview on groundwater as an unrecoverable resource; thus, it is necessary that scientific disciplines like hydrogeology and psycho-sociology be considered together in a comprehensive approach for every groundwater study.

  4. 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.

  5. Biogeochemical gradients above a coal tar DNAPL

    Energy Technology Data Exchange (ETDEWEB)

    Scherr, Kerstin E., E-mail: kerstin.brandstaetter-scherr@boku.ac.at [University of Natural Resources and Life Sciences Vienna (BOKU), Department IFA-Tulln, Institute for Environmental Biotechnology, Konrad Lorenz Strasse 20, 3430 Tulln (Austria); Backes, Diana [University of Natural Resources and Life Sciences Vienna (BOKU), Department IFA-Tulln, Institute for Environmental Biotechnology, Konrad Lorenz Strasse 20, 3430 Tulln (Austria); Scarlett, Alan G. [University of Plymouth, Petroleum and Environmental Geochemistry Group, Biogeochemistry Research Centre, Drake Circus, Plymouth, Devon PL4 8AA (United Kingdom); Lantschbauer, Wolfgang [Government of Upper Austria, Directorate for Environment and Water Management, Division for Environmental Protection, Kärntner Strasse 10-12, 4021 Linz (Austria); Nahold, Manfred [GUT Gruppe Umwelt und Technik GmbH, Ingenieurbüro für Technischen Umweltschutz, Plesching 15, 4040 Linz (Austria)

    2016-09-01

    Naturally occurring distribution and attenuation processes can keep hydrocarbon emissions from dense non aqueous phase liquids (DNAPL) into the adjacent groundwater at a minimum. In a historically coal tar DNAPL-impacted site, the de facto absence of a plume sparked investigations regarding the character of natural attenuation and DNAPL resolubilization processes at the site. Steep vertical gradients of polycyclic aromatic hydrocarbons, microbial community composition, secondary water quality and redox-parameters were found to occur between the DNAPL-proximal and shallow waters. While methanogenic and mixed-electron acceptor conditions prevailed close to the DNAPL, aerobic conditions and very low dissolved contaminant concentrations were identified in three meters vertical distance from the phase. Comprehensive two-dimensional gas chromatography–mass spectrometry (GC × GC–MS) proved to be an efficient tool to characterize the behavior of the present complex contaminant mixture. Medium to low bioavailability of ferric iron and manganese oxides of aquifer samples was detected via incubation with Shewanella alga and evidence for iron and manganese reduction was collected. In contrast, 16S rDNA phylogenetic analysis revealed the absence of common iron reducing bacteria. Aerobic hydrocarbon degraders were abundant in shallow horizons, while nitrate reducers were dominating in deeper aquifer regions, in addition to a low relative abundance of methanogenic archaea. Partial Least Squares – Canonical Correspondence Analysis (PLS-CCA) suggested that nitrate and oxygen concentrations had the greatest impact on aquifer community structure in on- and offsite wells, which had a similarly high biodiversity (H’ and Chao1). Overall, slow hydrocarbon dissolution from the DNAPL appears to dominate natural attenuation processes. This site may serve as a model for developing legal and technical strategies for the treatment of DNAPL-impacted sites where contaminant plumes are

  6. Representing AIDS in Comics.

    Science.gov (United States)

    Czerwiec, M K

    2018-02-01

    Matthew P. McAllister wrote: "Comic books can and have contributed positively to the discourse about AIDS: images that encourage true education, understanding and compassion can help cope with a biomedical condition which has more than a biomedical relevance" [1]. With this in mind, I combined a 23-narrator oral history and my personal memoir about an inpatient Chicago AIDS hospital unit in my book, Taking Turns: Stories from HIV/AIDS Care Unit 371. In doing so, I built upon the existing rich history of HIV/AIDS in comics, which this article will briefly describe. Although not a comprehensive review of the intersection of AIDS and comics, the book is a tour through influences that proved useful to me. In addition, in making my book, I faced a distinct ethical issue with regard to representing patient experiences with HIV/AIDS, and I describe here how I addressed it. © 2018 American Medical Association. All Rights Reserved.

  7. Representative of the municipality

    International Nuclear Information System (INIS)

    Castellnou Barcelo, J.

    2007-01-01

    Full text of publication follows. The decommissioning of the Vandellos-I nuclear power plant was a big challenge for the host community of Vandellos i l'Hospitalet de l'Infant and the close-by region. Closing down of the facility resulted in a rise of unemployment and a decrease of municipal income. The public was concerned with three issues: safety, transparency and information about the decommissioning, and economic future. Therefore, from the very beginning, municipal governments entered into negotiations with ENRESA on socio-economic benefits, including local employment in dismantling activities, and other types of financial and non-financial compensation. The ADE business association, i.e. a network of business organisations was created that guided the allotment of work to local firms. To satisfy public demand, local municipalities focused on the triad of safety, dialogue and local development, considered the three 'pillars of trust'. A Municipal Monitoring Commission was created, made up of representatives of affected municipalities, the regional government, the ADE business association, trade unions, the local university, the NPP management and ENRESA to monitor the dismantling process and regularly inform the local public. Items that were handled by this Commission included: - Work process monitoring. - Workers. - Materials Control. - Conventional and radioactive or contaminated waste management. - Emanation waste management (liquid and gas) - Safety (training and accidents). - Surveillance (radiological and environmental: dust, noise). - Effects. - Fulfillment of agreed conditions. A number of communication tools and channels were used, e.g., public information meetings, an information centre, the municipal magazine, the municipal radio station, and meetings with representatives of the local press. Particularly innovative was the idea to ask academics from the University of Tarragona to help with 'translating' technical information into language that could

  8. Characterization of gradient control systems

    NARCIS (Netherlands)

    Cortés, Jorge; van der Schaft, Arjan; Crouch, Peter E.

    2005-01-01

    Given a general nonlinear affine control system with outputs and a torsion-free affine connection defined on its state space, we investigate the gradient realization problem: we give necessary and sufficient conditions under which the control system can be written as a gradient control system

  9. Characterization of Gradient Control Systems

    NARCIS (Netherlands)

    Cortés, Jorge; Schaft, Arjan van der; Crouch, Peter E.

    2005-01-01

    Given a general nonlinear affine control system with outputs and a torsion-free affine connection defined on its state space, we investigate the gradient realization problem: we give necessary and sufficient conditions under which the control system can be written as a gradient control system

  10. Sobolev gradients and differential equations

    CERN Document Server

    Neuberger, J W

    2010-01-01

    A Sobolev gradient of a real-valued functional on a Hilbert space is a gradient of that functional taken relative to an underlying Sobolev norm. This book shows how descent methods using such gradients allow a unified treatment of a wide variety of problems in differential equations. For discrete versions of partial differential equations, corresponding Sobolev gradients are seen to be vastly more efficient than ordinary gradients. In fact, descent methods with these gradients generally scale linearly with the number of grid points, in sharp contrast with the use of ordinary gradients. Aside from the first edition of this work, this is the only known account of Sobolev gradients in book form. Most of the applications in this book have emerged since the first edition was published some twelve years ago. What remains of the first edition has been extensively revised. There are a number of plots of results from calculations and a sample MatLab code is included for a simple problem. Those working through a fair p...

  11. Electric field gradients in metals

    International Nuclear Information System (INIS)

    Schatz, G.

    1979-01-01

    A review of the recent works on electric field gradient in metals is given. The main emphasis is put on the temperature dependence of the electric field gradient in nonmagnetic metals. Some methods of investigation of this effect using nuclear probes are described. One of them is nuclear accoustic resonance method. (S.B.)

  12. 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

  13. Impacts of swine manure pits on groundwater quality

    International Nuclear Information System (INIS)

    Krapac, I.G.; Dey, W.S.; Roy, W.R.; Smyth, C.A.; Storment, E.; Sargent, S.L.; Steele, J.D.

    2002-01-01

    New information is presented on impacts on groundwater by manure storage in deep ground pits. - Manure deep-pits are commonly used to store manure at confined animal feeding operations. However, previous to this study little information had been collected on the impacts of deep-pits on groundwater quality to provide science-based guidance in formulating regulations and waste management strategies that address risks to human health and the environment. Groundwater quality has been monitored since January 1999 at two hog finishing facilities in Illinois that use deep-pit systems for manure storage. Groundwater samples were collected on a monthly basis and analyzed for inorganic and bacteriological constituent concentrations. The two sites are located in areas with geologic environments representing different vulnerabilities for local groundwater contamination. One site is underlain by more than 6 m of clayey silt, and 7-36 m of shale. Concentrations of chloride, ammonium, phosphate, and potassium indicated that local groundwater quality had not been significantly impacted by pit leakage from this facility. Nitrate concentrations were elevated near the pit, often exceeding the 10 mg N/l drinking water standard. Isotopic nitrate signatures suggested that the nitrate was likely derived from soil organic matter and fertilizer applied to adjacent crop fields. At the other site, sandstone is located 4.6-6.1 m below land surface. Chloride concentrations and δ 15 N and δ 18 O values of dissolved nitrate indicated that this facility may have limited and localized impacts on groundwater. Other constituents, including ammonia, potassium, phosphate, and sodium were generally at or less than background concentrations. Trace- and heavy-metal concentrations in groundwater samples collected from both facilities were at concentrations less than drinking water standards. The concentration of inorganic constituents in the groundwater would not likely impact human health. Fecal

  14. Impacts of swine manure pits on groundwater quality

    Energy Technology Data Exchange (ETDEWEB)

    Krapac, I.G.; Dey, W.S.; Roy, W.R.; Smyth, C.A.; Storment, E.; Sargent, S.L.; Steele, J.D

    2002-12-01

    New information is presented on impacts on groundwater by manure storage in deep ground pits. - Manure deep-pits are commonly used to store manure at confined animal feeding operations. However, previous to this study little information had been collected on the impacts of deep-pits on groundwater quality to provide science-based guidance in formulating regulations and waste management strategies that address risks to human health and the environment. Groundwater quality has been monitored since January 1999 at two hog finishing facilities in Illinois that use deep-pit systems for manure storage. Groundwater samples were collected on a monthly basis and analyzed for inorganic and bacteriological constituent concentrations. The two sites are located in areas with geologic environments representing different vulnerabilities for local groundwater contamination. One site is underlain by more than 6 m of clayey silt, and 7-36 m of shale. Concentrations of chloride, ammonium, phosphate, and potassium indicated that local groundwater quality had not been significantly impacted by pit leakage from this facility. Nitrate concentrations were elevated near the pit, often exceeding the 10 mg N/l drinking water standard. Isotopic nitrate signatures suggested that the nitrate was likely derived from soil organic matter and fertilizer applied to adjacent crop fields. At the other site, sandstone is located 4.6-6.1 m below land surface. Chloride concentrations and {delta}{sup 15}N and {delta}{sup 18}O values of dissolved nitrate indicated that this facility may have limited and localized impacts on groundwater. Other constituents, including ammonia, potassium, phosphate, and sodium were generally at or less than background concentrations. Trace- and heavy-metal concentrations in groundwater samples collected from both facilities were at concentrations less than drinking water standards. The concentration of inorganic constituents in the groundwater would not likely impact human

  15. The geomagnetic field gradient tensor

    DEFF Research Database (Denmark)

    Kotsiaros, Stavros; Olsen, Nils

    2012-01-01

    We develop the general mathematical basis for space magnetic gradiometry in spherical coordinates. The magnetic gradient tensor is a second rank tensor consisting of 3 × 3 = 9 spatial derivatives. Since the geomagnetic field vector B is always solenoidal (∇ · B = 0) there are only eight independent...... tensor elements. Furthermore, in current free regions the magnetic gradient tensor becomes symmetric, further reducing the number of independent elements to five. In that case B is a Laplacian potential field and the gradient tensor can be expressed in series of spherical harmonics. We present properties...... of the magnetic gradient tensor and provide explicit expressions of its elements in terms of spherical harmonics. Finally we discuss the benefit of using gradient measurements for exploring the Earth’s magnetic field from space, in particular the advantage of the various tensor elements for a better determination...

  16. Opportunity for peri-urban Perth groundwater trade

    Science.gov (United States)

    Gao, Lei; Connor, Jeff; Doble, Rebecca; Ali, Riasat; McFarlane, Don

    2013-07-01

    Groundwater trade is widely advocated for reallocating scarce groundwater resources between competing users, and managing over-allocated and declining aquifers. However, groundwater markets are still in their infancy, and the potential benefits and opportunities need investigation, particularly where there is a need to reduce the extraction from declining aquifers. This article evaluates economic impacts of reducing groundwater extraction for irrigation use in peri-urban Perth, Australia, where irrigation, a lake-based ecosystem, and public water supply are highly dependent on a declining groundwater resource. We present an assessment of market-based water trading approaches to reduce groundwater extraction with an economic model representing diversity in returns to groundwater use across a population of irrigators. The results indicate that potential economic costs of a proportional reduction in available groundwater for irrigation are 18-21% less if groundwater trade is possible. We also evaluate a water buyback from irrigation to provide public water supply as an alternative to new infrastructure. We find that buying back up to around 50% of current irrigation allocations could create new public water supply only at the cost of 0.32-0.39 million per GL, which is less than one fifth of the costs of new desalinisation or recycled water supply options (2-3 million per GL). We conclude that, with rapid development of computer and internet based trading platforms that allows fast, efficient and low cost multiple party trading, it is increasingly feasible to realise the economic potentials of market-based trade approaches for managing overexploited aquifers.

  17. Headcut erosive regimes influenced by groundwater on disturbed agricultural soils.

    Science.gov (United States)

    Rockwell, D L

    2011-02-01

    A series of simulated rainfall experiments, testing several soils and slope gradients in a 10 m x 0.8m laboratory flume, displayed close correlations between initial development of a water table at a 10 cm depth and highly erosive headcut formation. On some soils and gradients, highly erosive headcuts formed consistently and predictably within minutes or seconds of initial water table rise. However, headcuts alone were not good indicators of increased erosion. In most experiments some headcuts formed early, often when surface hydraulic parameter values reached established rill initiation thresholds, but resulted in little or no erosion increase. Later, at initial water table rise, other headcuts formed coincident with major erosion increase, often with surface hydraulic values then less than rill initiation thresholds. On the four soils tested, highly erosive headcuts never formed without groundwater development, except on steep 9 ° slopes. Common visual indicators such as headcut morphology and headcut advance rates were not effective means of determining either erosion or the existence of groundwater. Only local monitoring of subsurface moisture conditions with micro-standpipes and TDR aided in determining headcut processes and erosive regimes. Groundwater-influenced headcut formation was likely caused by increased soil pore-water pressures and decreased soil shear strengths in surface rainflow, not by sapping or seepage from the soil matrix. Highly erosive headcuts can thus form under common agricultural conditions where reductions in permeability, such as plow pans, exist near the surface--without the need for saturated soils. Headcut erosive regimes were also significantly influenced by soil type and slope gradient, with the greatest effects of groundwater on moderate slopes and fairly permeable soils. Copyright © 2010. Published by Elsevier Ltd.

  18. Determinants of Shallow Groundwater As Variability in Bangladesh

    Science.gov (United States)

    Radloff, K. A.; Zheng, Y.; Stute, M.; Rahman, M.; Mihajlov, I.; Siu, H.; Huq, M.; Choudhury, I.; Ahmed, K.; van Geen, A.

    2010-12-01

    Manually operated tube wells that tap into shallow aquifers remain a critical source of untreated drinking water in south Asia and an estimated 37 million people are still exposed to elevated levels of As in Bangladesh(1). This field effort sought to address two questions. What mechanisms control the partitioning of As between groundwater and sediment? How does groundwater transport affect the spatial variability of dissolved As? Understanding the source of groundwater variability is essential for understanding how [As] will change with time, especially as Bangladesh and its water demands develop. Arsenic mobility and transport within the shallow aquifer was investigated at a 0.5 km2 site where [As] increases from conditions measured by spiking freshly collected sediment was remarkably uniform: Kd = 1.5 ± 0.5 L/kg, at 14 of 15 locations. Push- pull tests were used to alter groundwater [As] surrounding a well, without disturbing the sediment. The aquifer responded to the imposed dis-equilibrium by either adsorbing or desorbing As within a few days. These results provide further evidence that groundwater [As] is controlled by As sorption reactions with the sediment that reach equilibrium rapidly compared to the time scale of groundwater flow. A simple reactive-transport model for the site based on the measured partitioning coefficient, Kd, however, supports the notion that the [As] gradient observed reflects the gradual removal of As by groundwater flow over hundreds to thousands of years. The onset of irrigation and industrial pumping at this site has induced a reversal in flow, consequently groundwater now moves from high [As] into low [As] areas. This change could result in rising [As] to levels >50 μg/L in the village within the next few decades. The rapid economic development of Bangladesh could induce similar changes in groundwater flow, and thus As concentrations, elsewhere. This suggests that periodic monitoring of shallow wells low in As within regions of

  19. Hydrogeologic framework, arsenic distribution, and groundwater geochemistry of the glacial-sediment aquifer at the Auburn Road landfill superfund site, Londonderry, New Hampshire

    Science.gov (United States)

    Degnan, James R.; Harte, Philip T.

    2013-01-01

    been observed in the wetland, streams, and pond downgradient of the landfills. Piezometers were installed in some of these locations to confirm groundwater discharge, measure vertical-flow gradients, and to provide a way to sample the discharging groundwater. Understanding the movement of leachate in groundwater is complicated by the presence of preferential flow paths through aquifer materials with differing hydraulic properties; these preferential flow paths can affect rates of recharge, geochemical conditions, and contaminant fluxes. In areas adjacent to the three capped landfills, infiltration of precipitation containing oxygenated water through permeable deltaic sediments in the former gravel pit area causes increases in dissolved oxygen concentrations and decreases in arsenic concentrations. Layered deltaic sediments produce anisotropic hydraulic characteristics and zones of high hydraulic conductivity. The glacial-sediment aquifer also includes glaciolacustrine sediments that have low permeability and limit infiltration at the surface Discharge of leachate-affected groundwater may be limited in areas of organic muck on the bottom of Whispering Pines Pond because the muck may act as a semiconfining layer. Geophysical survey results were used to identify several areas with continuous beds of muck and an underlying highresistivity layer on top of a layer of low resistivity that may represent leachate-affected groundwater. The high-resistivity layer is likely groundwater associated with oxygenated recharge, which would cause arsenic to adsorb onto aquifer sediments and reduce concentrations of dissolved arsenic in groundwater. Surface and borehole geophysical data collected in 2011 were used to identify potentially high-permeability or contaminated zones in the aquifer (preferential flowpaths) as well as low-permeability zones that may promote contamination through back diffusion. Some groundwater in parts of the glacial-sediment aquifer where the leachate plumes

  20. Effects of temperature changes on groundwater ecosystems

    Science.gov (United States)

    Griebler, Christian; Kellermann, Claudia; Schreglmann, Kathrin; Lueders, Tillmann; Brielmann, Heike; Schmidt, Susanne; Kuntz, David; Walker-Hertkorn, Simone

    2014-05-01

    The use of groundwater as a carrier of thermal energy is becoming more and more important as a sustainable source of heating and cooling. At the same time, the present understanding of the effects of aquifer thermal usage on geochemical and biological aquifer ecosystem functions is extremely limited. Recently we started to assess the effects of temperature changes in groundwater on the ecological integrity of aquifers. In a field study, we have monitored hydrogeochemical, microbial, and faunal parameters in groundwater of an oligotrophic aquifer in the vicinity of an active thermal discharge facility. The observed seasonal variability of abiotic and biotic parameters between wells was considerable. Yet, due to the energy-limited conditions no significant temperature impacts on bacterial or faunal abundances and on bacterial productivity were observed. In contrast, the diversity of aquifer bacterial communities and invertebrate fauna was either positively or negatively affected by temperature, respectively. In follow-up laboratory experiments temperature effects were systematically evaluated with respect to energy limitation (e.g. establishment of unlimited growth conditions), geochemistry (e.g. dynamics of DOC and nutrients), microbiology (e.g. survival of pathogens), and fauna (temperature preference and tolerance). First, with increased nutrient and organic carbon concentrations even small temperature changes revealed microbiological dynamics. Second, considerable amounts of adsorbed DOC were mobilized from sediments of different origin with an increase in temperatures. No evidence was obtained for growth of pathogenic bacteria and extended survival of viruses at elevated temperatures. Invertebrates clearly preferred natural thermal conditions (10-12°C), where their highest frequency of appearance was measured in a temperature gradient. Short-term incubations (48h) of invertebrates in temperature dose-response tests resulted in LT50 (lethal temperature) values

  1. Investigating the spatio-temporal variability in groundwater and surface water interactions: a multi-technique approach

    Science.gov (United States)

    Unland, N. P.; Cartwright, I.; Andersen, M. S.; Rau, G. C.; Reed, J.; Gilfedder, B. S.; Atkinson, A. P.; Hofmann, H.

    2013-09-01

    The interaction between groundwater and surface water along the Tambo and Nicholson rivers, southeast Australia, was investigated using 222Rn, Cl, differential flow gauging, head gradients, electrical conductivity (EC) and temperature profiles. Head gradients, temperature profiles, Cl concentrations and 222Rn activities all indicate higher groundwater fluxes to the Tambo River in areas of increased topographic variation where the potential to form large groundwater-surface water gradients is greater. Groundwater discharge to the Tambo River calculated by Cl mass balance was significantly lower (1.48 × 104 to 1.41 × 103 m3 day-1) than discharge estimated by 222Rn mass balance (5.35 × 105 to 9.56 × 103 m3 day-1) and differential flow gauging (5.41 × 105 to 6.30 × 103 m3 day-1) due to bank return waters. While groundwater sampling from the bank of the Tambo River was intended to account for changes in groundwater chemistry associated with bank infiltration, variations in bank infiltration between sample sites remain unaccounted for, limiting the use of Cl as an effective tracer. Groundwater discharge to both the Tambo and Nicholson rivers was the highest under high-flow conditions in the days to weeks following significant rainfall, indicating that the rivers are well connected to a groundwater system that is responsive to rainfall. Groundwater constituted the lowest proportion of river discharge during times of increased rainfall that followed dry periods, while groundwater constituted the highest proportion of river discharge under baseflow conditions (21.4% of the Tambo in April 2010 and 18.9% of the Nicholson in September 2010).

  2. Investigating the spatio-temporal variability in groundwater and surface water interactions: a multi-technical approach

    Science.gov (United States)

    Unland, N. P.; Cartwright, I.; Andersen, M. S.; Rau, G. C.; Reed, J.; Gilfedder, B. S.; Atkinson, A. P.; Hofmann, H.

    2013-03-01

    The interaction between groundwater and surface water along the Tambo and Nicholson Rivers, southeast Australia, was investigated using 222Rn, Cl, differential flow gauging, head gradients, electrical conductivity (EC) and temperature profiling. Head gradients, temperature profiles, Cl concentrations and 222Rn activities all indicate higher groundwater fluxes to the Tambo River in areas of increased topographic variation where the potential to form large groundwater-surface water gradients is greater. Groundwater discharge to the Tambo River calculated by Cl mass balance was significantly lower (1.48 × 104 to 1.41 × 103 m3 day-1) than discharge estimated by 222Rn mass balance (5.35 × 105 to 9.56 × 103 m3 day-1) and differential flow gauging (5.41 × 105 to 6.30 × 103 m3 day-1). While groundwater sampling from the bank of the Tambo River was intended to account for the variability in groundwater chemistry associated with river-bank interaction, the spatial variability under which these interactions occurs remained unaccounted for, limiting the use of Cl as an effective tracer. Groundwater discharge to both the Tambo and Nicholson Rivers was the highest under high flow conditions in the days to weeks following significant rainfall, indicating that the rivers are well connected to a groundwater system that is responsive to rainfall. Groundwater constituted the lowest proportion of river discharge during times of increased rainfall that followed dry periods, while groundwater constituted the highest proportion of river discharge under baseflow conditions (21.4% of the Tambo in April 2010 and 18.9% of the Nicholson in September 2010).

  3. 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

  4. 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

  5. A report on isotope hydrology of groundwater in Bangladesh: implications for characterization and mitigation of arsenic in groundwater

    Energy Technology Data Exchange (ETDEWEB)

    Aggarwal, P K; Froehlich, K [International Atomic Energy Agency, Isotope Hydrology Section, Vienna (Austria); Basu, A R; Poreda, R J [Department of Earth Sciences, University of Rochester Rochester, New York (United States); Kulkarni, K M [Bhabha Atomic Research Centre, Isotope Hydrology Section, Trombay, Mumbai (India); Tarafdar, S A; Ali, Mohamed; Ahmed, Nasir [Bangladesh Atomic Energy Commission, Dhaka (Bangladesh); Hussain, Alamgir; Rahman, Mizanur; Ahmed, Syed Reazuddin [Bangladesh Water Development Board, Dhaka (Bangladesh)

    2000-12-01

    An investigation of the source and dynamics of groundwater in Bangladesh has been conducted with environmental isotope tracers. The primary objective of this study was to provide a scientific basis for developing mitigation strategies by characterizing the mechanism of arsenic mobilization in groundwater and the present and future status of arsenic contamination in deeper aquifers. About 55 shallow and deep groundwater samples ranging in depth from 10 to 335 m were collected and analyzed for their chemical and isotopic compositions. Distinct patterns of isotope compositions are found in shallow and deep groundwaters. Arsenic contamination is found to be present mostly in shallow groundwater to depths of less than 70 m. Groundwater samples from deep wells containing elevated arsenic concentrations are found to contain water mostly from shallow aquifers and do not indicate arsenic contamination of deeper aquifers. However, depth in itself is not a criterion that can be reliably or easily used to find arsenic-free, safe drinking water. Water with high arsenic concentrations sampled from 'deep' wells may not be representative of deep aquifers, and presently uncontaminated water from somewhat deeper wells ({approx}100 m) may not remain so over a long period of time. Increased exploitation of deep groundwater ({approx}300 m) such as in the Barisal area appears to be possible without fear of arsenic contamination from shallow aquifers. However, the potential for groundwater mining is clearly evident and the sustainability of this resource needs to be evaluated. The exponential increase in groundwater exploitation between 1979 and 1999 does not appear to have affected the overall hydrodynamics of shallow and deep aquifers and, by implication, the arsenic mobilization processes. Currently favored mechanisms of arsenic mobilization are found to be inconsistent with isotope data. The most likely process of arsenic mobilization may involve desorption from the sediments as a

  6. A report on isotope hydrology of groundwater in Bangladesh: implications for characterization and mitigation of arsenic in groundwater

    International Nuclear Information System (INIS)

    Aggarwal, P.K.; Froehlich, K.; Basu, A.R.; Poreda, R.J.; Kulkarni, K.M.; Tarafdar, S.A.; Mohamed Ali; Nasir Ahmed; Alamgir Hussain; Mizanur Rahman; Syed Reazuddin Ahmed

    2000-12-01

    An investigation of the source and dynamics of groundwater in Bangladesh has been conducted with environmental isotope tracers. The primary objective of this study was to provide a scientific basis for developing mitigation strategies by characterizing the mechanism of arsenic mobilization in groundwater and the present and future status of arsenic contamination in deeper aquifers. About 55 shallow and deep groundwater samples ranging in depth from 10 to 335 m were collected and analyzed for their chemical and isotopic compositions. Distinct patterns of isotope compositions are found in shallow and deep groundwaters. Arsenic contamination is found to be present mostly in shallow groundwater to depths of less than 70 m. Groundwater samples from deep wells containing elevated arsenic concentrations are found to contain water mostly from shallow aquifers and do not indicate arsenic contamination of deeper aquifers. However, depth in itself is not a criterion that can be reliably or easily used to find arsenic-free, safe drinking water. Water with high arsenic concentrations sampled from 'deep' wells may not be representative of deep aquifers, and presently uncontaminated water from somewhat deeper wells (∼100 m) may not remain so over a long period of time. Increased exploitation of deep groundwater (∼300 m) such as in the Barisal area appears to be possible without fear of arsenic contamination from shallow aquifers. However, the potential for groundwater mining is clearly evident and the sustainability of this resource needs to be evaluated. The exponential increase in groundwater exploitation between 1979 and 1999 does not appear to have affected the overall hydrodynamics of shallow and deep aquifers and, by implication, the arsenic mobilization processes. Currently favored mechanisms of arsenic mobilization are found to be inconsistent with isotope data. The most likely process of arsenic mobilization may involve desorption from the sediments as a result of

  7. Response of groundwater level and surface-water/groundwater interaction to climate variability: Clarence-Moreton Basin, Australia

    Science.gov (United States)

    Cui, Tao; Raiber, Matthias; Pagendam, Dan; Gilfedder, Mat; Rassam, David

    2018-03-01

    Understanding the response of groundwater levels in alluvial and sedimentary basin aquifers to climatic variability and human water-resource developments is a key step in many hydrogeological investigations. This study presents an analysis of groundwater response to climate variability from 2000 to 2012 in the Queensland part of the sedimentary Clarence-Moreton Basin, Australia. It contributes to the baseline hydrogeological understanding by identifying the primary groundwater flow pattern, water-level response to climate extremes, and the resulting dynamics of surface-water/groundwater interaction. Groundwater-level measurements from thousands of bores over several decades were analysed using Kriging and nonparametric trend analysis, together with a newly developed three-dimensional geological model. Groundwater-level contours suggest that groundwater flow in the shallow aquifers shows local variations in the close vicinity of streams, notwithstanding general conformance with topographic relief. The trend analysis reveals that climate variability can be quickly reflected in the shallow aquifers of the Clarence-Moreton Basin although the alluvial aquifers have a quicker rainfall response than the sedimentary bedrock formations. The Lockyer Valley alluvium represents the most sensitively responding alluvium in the area, with the highest declining (-0.7 m/year) and ascending (2.1 m/year) Sen's slope rates during and after the drought period, respectively. Different surface-water/groundwater interaction characteristics were observed in different catchments by studying groundwater-level fluctuations along hydrogeologic cross-sections. The findings of this study lay a foundation for future water-resource management in the study area.

  8. Underground structures increasing the intrinsic vulnerability of urban groundwater: Sensitivity analysis and development of an empirical law based on a groundwater age modelling approach

    Science.gov (United States)

    Attard, Guillaume; Rossier, Yvan; Eisenlohr, Laurent

    2017-09-01

    In a previous paper published in Journal of Hydrology, it was shown that underground structures are responsible for a mixing process between shallow and deep groundwater that can favour the spreading of urban contamination. In this paper, the impact of underground structures on the intrinsic vulnerability of urban aquifers was investigated. A sensitivity analysis was performed using a 2D deterministic modelling approach based on the reservoir theory generalized to hydrodispersive systems to better understand this mixing phenomenon and the mixing affected zone (MAZ) caused by underground structures. It was shown that the maximal extent of the MAZ caused by an underground structure is reached approximately 20 years after construction. Consequently, underground structures represent a long-term threat for deep aquifer reservoirs. Regarding the construction process, draining operations have a major impact and favour large-scale mixing between shallow and deep groundwater. Consequently, dewatering should be reduced and enclosed as much as possible. The role played by underground structures' dimensions was assessed. The obstruction of the first aquifer layer caused by construction has the greatest influence on the MAZ. The cumulative impact of several underground structures was assessed. It was shown that the total MAZ area increases linearly with underground structures' density. The role played by materials' properties and hydraulic gradient were assessed. Hydraulic conductivity, anisotropy and porosity have the strongest influence on the development of MAZ. Finally, an empirical law was derived to estimate the MAZ caused by an underground structure in a bi-layered aquifer under unconfined conditions. This empirical law, based on the results of the sensitivity analysis developed in this paper, allows for the estimation of MAZ dimensions under known material properties and underground structure dimensions. This empirical law can help urban planners assess the area of

  9. Combining Step Gradients and Linear Gradients in Density.

    Science.gov (United States)

    Kumar, Ashok A; Walz, Jenna A; Gonidec, Mathieu; Mace, Charles R; Whitesides, George M

    2015-06-16

    Combining aqueous multiphase systems (AMPS) and magnetic levitation (MagLev) provides a method to produce hybrid gradients in apparent density. AMPS—solutions of different polymers, salts, or surfactants that spontaneously separate into immiscible but predominantly aqueous phases—offer thermodynamically stable steps in density that can be tuned by the concentration of solutes. MagLev—the levitation of diamagnetic objects in a paramagnetic fluid within a magnetic field gradient—can be arranged to provide a near-linear gradient in effective density where the height of a levitating object above the surface of the magnet corresponds to its density; the strength of the gradient in effective density can be tuned by the choice of paramagnetic salt and its concentrations and by the strength and gradient in the magnetic field. Including paramagnetic salts (e.g., MnSO4 or MnCl2) in AMPS, and placing them in a magnetic field gradient, enables their use as media for MagLev. The potential to create large steps in density with AMPS allows separations of objects across a range of densities. The gradients produced by MagLev provide resolution over a continuous range of densities. By combining these approaches, mixtures of objects with large differences in density can be separated and analyzed simultaneously. Using MagLev to add an effective gradient in density also enables tuning the range of densities captured at an interface of an AMPS by simply changing the position of the container in the magnetic field. Further, by creating AMPS in which phases have different concentrations of paramagnetic ions, the phases can provide different resolutions in density. These results suggest that combining steps in density with gradients in density can enable new classes of separations based on density.

  10. Groundwater contaminant plume ranking

    International Nuclear Information System (INIS)

    1988-08-01

    Containment plumes at Uranium Mill Tailings Remedial Action (UMTRA) Project sites were ranked to assist in Subpart B (i.e., restoration requirements of 40 CFR Part 192) compliance strategies for each site, to prioritize aquifer restoration, and to budget future requests and allocations. The rankings roughly estimate hazards to the environment and human health, and thus assist in determining for which sites cleanup, if appropriate, will provide the greatest benefits for funds available. The rankings are based on the scores that were obtained using the US Department of Energy's (DOE) Modified Hazard Ranking System (MHRS). The MHRS and HRS consider and score three hazard modes for a site: migration, fire and explosion, and direct contact. The migration hazard mode score reflects the potential for harm to humans or the environment from migration of a hazardous substance off a site by groundwater, surface water, and air; it is a composite of separate scores for each of these routes. For ranking the containment plumes at UMTRA Project sites, it was assumed that each site had been remediated in compliance with the EPA standards and that relict contaminant plumes were present. Therefore, only the groundwater route was scored, and the surface water and air routes were not considered. Section 2.0 of this document describes the assumptions and procedures used to score the groundwater route, and Section 3.0 provides the resulting scores for each site. 40 tabs

  11. Block-conjugate-gradient method

    International Nuclear Information System (INIS)

    McCarthy, J.F.

    1989-01-01

    It is shown that by using the block-conjugate-gradient method several, say s, columns of the inverse Kogut-Susskind fermion matrix can be found simultaneously, in less time than it would take to run the standard conjugate-gradient algorithm s times. The method improves in efficiency relative to the standard conjugate-gradient algorithm as the fermion mass is decreased and as the value of the coupling is pushed to its limit before the finite-size effects become important. Thus it is potentially useful for measuring propagators in large lattice-gauge-theory calculations of the particle spectrum

  12. 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.

  13. A flexoelectric theory with rotation gradient effects for elastic dielectrics

    International Nuclear Information System (INIS)

    Anqing, Li; Shenjie, Zhou; Lu, Qi; Xi, Chen

    2016-01-01

    In this paper, a general flexoelectric theory in the framework of couple stress theory is proposed for isotropic dielectrics, in which the rotation gradient and the polarization gradient are involved to represent the nonlocal mechanical and electrical effects, respectively. The present flexoelectric theory shows only the anti-symmetric part of rotation gradient can induce polarization, while the symmetric part of rotation gradient cannot induce polarization in isotropic dielectrics. The electrostatic stress is obtained naturally in the governing equations and boundary conditions in terms of the variational principle, which is composed of two parts: the Maxwell stress corresponding to the polarization and the remainder relating to the polarization gradient. The current theory is able to account for the effects of size, direct and inverse flexoelectricities, and electrostatic force. To illustrate this theory, a simple application of Bernoulli–Euler cantilever beam is discussed. The numerical results demonstrate neither the higher-order constant l 1 nor the higher-order constant l 2 associated with the symmetric and anti-symmetric parts of rotation gradient, respectively, can be ignored in the flexoelectric theory. In addition, the induced deflection increases as the increase of the flexoelectric coefficient. The polarization is no longer constant and the potential is no longer linear along the thickness direction of beam because of the influence of polarization gradient. (paper)

  14. Simulating groundwater-peatland interactions in depression and slope peatlands in southern Quebec (Canada)

    Science.gov (United States)

    Larocque, M.; Quillet, A.; Paniconi, C.

    2013-12-01

    four peatland transects considered representative of the overall variability observed at the field sites. The models are first calibrated to reproduce measured heads, head gradients and temporal variations. In order to assess typical flow patterns and exchanges, a global sensitivity analysis of the model are performed to identify which parameters and processes control the exchanged fluxes. Results show that for depression peatlands, exchanged aquifer-peatland fluxes occur on short distances near the peatland border. For slope peatlands, exchanged fluxes are distributed further inside the peatland. Local hydrostratigraphy as well as peat and mineral deposits hydraulic properties control aquifer-peatland exchanges. Peat recharge is a challenge to represent, but appears to have a similar effect on the four simulated peatlands. Based on the influence of each parameter on the flow, a graphical tool is proposed to help estimate the exchanges between groundwater and peatlands when limited data is available.

  15. Application of new point measurement device to quantify groundwater-surface water interactions

    DEFF Research Database (Denmark)

    Cremeans, Mackenzie; Devlin, J.F.; McKnight, Ursula S.

    2018-01-01

    The Streambed Point Velocity Probe (SBPVP) measures in situ groundwater velocities at the groundwater-surface water interface without reliance on hydraulic conductivity, porosity, or hydraulic gradient information. The tool operates on the basis of a mini-tracer test that occurs on the probe...... hydraulic head and temperature gradient data collected at similar scales. Spatial relationships of water flow through the streambed were found to be similar by all three methods, and indicated a heterogeneous pattern of groundwater-surface water exchange. The magnitudes of estimated flow varied to a greater...... degree. It was found that pollutants enter the stream in localized regions of high flow which do not always correspond to the locations of highest pollutant concentration. The results show the combined influence of flow and concentration on contaminant discharge and illustrate the advantages of adopting...

  16. Groundwater Waves in a Coastal Fractured Aquifer of the Third Phase Qinshan Nuclear Power Engineering Field

    Institute of Scientific and Technical Information of China (English)

    ZHOU Nian-qing; TANG Yi-qun; TANG He-ping

    2005-01-01

    Tidal fluctuations of Hangzhou Bay produce progressive pressure waves in adjacent field fractured aquifers, as the pressure waves propagate, groundwater levels and hydraulic gradients continuously fluctuate. The effect of tidal fluctuations on groundwater flow can be determined using the mean hydraulic gradient that can be calculated by comparing mean ground and surface water elevations. Tidal fluctuation is shown to affect the piezometer readings taken in a nearshore fractured aquifer around the nuclear power engineering field. Continuous monitoring of a network of seven piezometers provided relations between the tidal cycle and the piezometer readings. The relations can be expressed in times of a time and amplitude scaling factor. The time lag and the tidal effi ciency factor and wavelength are calculated using these parameters. It provides significant scientific basis to prevent tide and groundwater for the nuclear power engineering construction and safety run of nuclear power station in the future.

  17. Approaches to groundwater travel time

    International Nuclear Information System (INIS)

    Kaplan, P.; Klavetter, E.; Peters, R.

    1989-01-01

    One of the objectives of performance assessment for the Yucca Mountain Project is to estimate the groundwater travel time at Yucca Mountain, Nevada, to determine whether the site complies with the criteria specified in the Code of Federal Regulations, Title 10 CFR 60.113 (a). The numerical standard for performance in these criteria is based on the groundwater travel time along the fastest path of likely radionuclide transport from the disturbed zone to the accessible environment. The concept of groundwater travel time as proposed in the regulations, does not have a unique mathematical statement. The purpose of this paper is to discuss the ambiguities associated with the regulatory specification of groundwater travel time, two different interpretations of groundwater travel time, and the effect of the two interpretations on estimates of the groundwater travel time

  18. Approaches to groundwater travel time

    International Nuclear Information System (INIS)

    Kaplan, P.; Klavetter, E.; Peters, R.

    1989-01-01

    One of the objectives of performance assessment for the Yucca Mountain Project is to estimate the groundwater travel time at Yucca Mountain, Nevada, to determine whether the site complies with the criteria specified in the Code of Federal Regulations. The numerical standard for performance in these criteria is based on the groundwater travel time along the fastest path of likely radionuclide transport from the disturbed zone to the accessible environment. The concept of groundwater travel time, as proposed in the regulations, does not have a unique mathematical statement. The purpose of this paper is to discuss (1) the ambiguities associated with the regulatory specification of groundwater travel time, (2) two different interpretations of groundwater travel time, and (3) the effect of the two interpretations on estimates of the groundwater travel time. 3 refs., 2 figs., 2 tabs

  19. Scattering angle base filtering of the inversion gradients

    KAUST Repository

    Alkhalifah, Tariq Ali

    2014-01-01

    Full waveform inversion (FWI) requires a hierarchical approach based on the availability of low frequencies to maneuver the complex nonlinearity associated with the problem of velocity inversion. I develop a model gradient filter to help us access the parts of the gradient more suitable to combat this potential nonlinearity. The filter is based on representing the gradient in the time-lag normalized domain, in which low scattering angles of the gradient update are initially muted. The result are long-wavelength updates controlled by the ray component of the wavefield. In this case, even 10 Hz data can produce near zero wavelength updates suitable for a background correction of the model. Allowing smaller scattering angle to contribute provides higher resolution information to the model.

  20. Conditioning the full waveform inversion gradient to welcome anisotropy

    KAUST Repository

    Alkhalifah, Tariq Ali

    2014-01-01

    Multi-parameter full waveform inversion (FWI) suffers from the complex nonlinearity in the objective function, compounded by the eventual tradeoff between the model parameters. A hierarchical approach based on frequency and arrival time data decimation to maneuver the complex nonlinearity associated with this problem usually falls short in anisotropic media. In place of data decimation, I use a model gradient filter approach to access the parts of the gradient more suitable to combat the potential nonlinearity and parameter trade off. The filter is based on representing the gradient in the time-lag normalized domain in which the small scattering angles of the gradient update is initially muted out. A model update hierarchical filtering strategy includes applying varying degree of filtering to the different parameter updates. A feature not easily accessible to simple data decimation. Using both FWI and reection based FWI (RFWI), two strategies to combat the tradeoff between anisotropic parameters are outlined.

  1. Conditioning the full waveform inversion gradient to welcome anisotropy

    KAUST Repository

    Alkhalifah, Tariq Ali

    2014-08-05

    Multi-parameter full waveform inversion (FWI) suffers from the complex nonlinearity in the objective function, compounded by the eventual tradeoff between the model parameters. A hierarchical approach based on frequency and arrival time data decimation to maneuver the complex nonlinearity associated with this problem usually falls short in anisotropic media. In place of data decimation, I use a model gradient filter approach to access the parts of the gradient more suitable to combat the potential nonlinearity and parameter trade off. The filter is based on representing the gradient in the time-lag normalized domain in which the small scattering angles of the gradient update is initially muted out. A model update hierarchical filtering strategy includes applying varying degree of filtering to the different parameter updates. A feature not easily accessible to simple data decimation. Using both FWI and reection based FWI (RFWI), two strategies to combat the tradeoff between anisotropic parameters are outlined.

  2. Report and analysis of the BULLION forced-gradient experiment

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-08-01

    The BULLION Forced-Gradient Experiment (FGE) was conducted in the summer of 1997, starting June 2 and ending August 28. The site of the experiment was the ER-20-6 well field adjacent to the BULLION test. Figure 1-1 shows the location of this site on Pahute Mesa in Area 20 of the Nevada Test Site. Figure 1-2 shows the ER-20-6 site within the Pahute Mesa hydrogeologic framework, and Figure 1-3 shows the site layout with respect to the BULLION test. The purpose of the BULLION FGE was to provide information relevant to the transport of radionuclides in groundwater. Transport of radionuclides from Pahute Mesa is of special concern due to the potential for rapid movement of groundwater in the fractured volcanic rocks comprising the Mesa and formations along the anticipated downgradient path of groundwater. The objective was specifically to observe the transport process and characterize transport parameters (e.g., effective porosity, dispersivity and matrix diffusion) for use in predictive modeling of contaminant transport. Additional objectives were to characterize the hydrologic source term and the relative mobility of mobile radionuclides.

  3. Imaging the Buried Chicxulub Crater with Gravity Gradients and Cenotes

    Science.gov (United States)

    Hildebrand, A. R.; Pilkington, M.; Halpenny, J. F.; Ortiz-Aleman, C.; Chavez, R. E.; Urrutia-Fucugauchi, J.; Connors, M.; Graniel-Castro, E.; Camara-Zi, A.; Vasquez, J.

    1995-09-01

    Differing interpretations of the Bouguer gravity anomaly over the Chicxulub crater, Yucatan Peninsula, Mexico, have yielded diameter estimates of 170 to 320 km. Knowing the crater's size is necessary to quantify the lethal perturbations to the Cretaceous environment associated with its formation. The crater's size (and internal structure) is revealed by the horizontal gradient of the Bouguer gravity anomaly over the structure, and by mapping the karst features of the Yucatan region. To improve our resolution of the crater's gravity signature we collected additional gravity measurements primarily along radial profiles, but also to fill in previously unsurveyed areas. Horizontal gradient analysis of Bouguer gravity data objectively highlights the lateral density contrasts of the impact lithologies and suppresses regional anomalies which may obscure the gravity signature of the Chicxulub crater lithologies. This gradient technique yields a striking circular structure with at least 6 concentric gradient features between 25 and 85 km radius. These features are most distinct in the southwest probably because of denser sampling of the gravity field. Our detailed profiles detected an additional feature and steeper gradients (up to 5 mGal/km) than the original survey. We interpret the outer four gradient maxima to represent concentric faults in the crater's zone of slumping as is also revealed by seismic reflection data. The inner two probably represent the margin of the central uplift and the peak ring and or collapsed transient cavity. Radial gradients in the SW quadrant over the inferred ~40 km-diameter central uplift (4) may represent structural "puckering" as revealed at eroded terrestrial craters. Gradient features related to regional gravity highs and lows are visible outside the crater, but no concentric gradient features are apparent at distances > 90 km radius. The marginal gradient features may be modelled by slump faults as observed in large complex craters on

  4. Ground-water travel time

    International Nuclear Information System (INIS)

    Bentley, H.; Grisak, G.

    1985-01-01

    The Containment and Isolation Working Group considered issues related to the postclosure behavior of repositories in crystalline rock. This working group was further divided into subgroups to consider the progress since the 1978 GAIN Symposium and identify research needs in the individual areas of regional ground-water flow, ground-water travel time, fractional release, and cumulative release. The analysis and findings of the Ground-Water Travel Time Subgroup are presented

  5. Regional ground-water system

    International Nuclear Information System (INIS)

    Long, J.

    1985-01-01

    The Containment and Isolation Working Group considered issues related to the postclosure behavior of repositories in crystalline rock. This working group was further divided into subgroups to consider the progress since the 1978 GAIN Symposium and identify research needs in the individual areas of regional ground-water flow, ground-water travel time, fractional release, and cumulative release. The analysis and findings of the Ground-Water Regime Subgroup are presented

  6. Adsorptive Iron Removal from Groundwater

    OpenAIRE

    Sharma, S.K.

    2001-01-01

    Iron is commonly present in groundwater worldwide. The presence of iron in the water supply is not harmful to human health, however it is undesirable. Bad taste, discoloration, staining, deposition in the distribution system leading to aftergrowth, and incidences of high turbidity are some of the aesthetic and operational problems associated with iron in water supplies. Iron removal from groundwater is, therefore, a major concern for water supply companies using groundwater sources....

  7. GROUNDWATER PROTECTION MANAGEMENT PROGRAM DESCRIPTION.

    Energy Technology Data Exchange (ETDEWEB)

    PAQUETTE,D.E.; BENNETT,D.B.; DORSCH,W.R.; GOODE,G.A.; LEE,R.J.; KLAUS,K.; HOWE,R.F.; GEIGER,K.

    2002-05-31

    THE DEPARTMENT OF ENERGY ORDER 5400.1, GENERAL ENVIRONMENTAL PROTECTION PROGRAM, REQUIRES THE DEVELOPMENT AND IMPLEMENTATION OF A GROUNDWATER PROTECTION PROGRAM. THE BNL GROUNDWATER PROTECTION MANAGEMENT PROGRAM DESCRIPTION PROVIDES AN OVERVIEW OF HOW THE LABORATORY ENSURES THAT PLANS FOR GROUNDWATER PROTECTION, MONITORING, AND RESTORATION ARE FULLY DEFINED, INTEGRATED, AND MANAGED IN A COST EFFECTIVE MANNER THAT IS CONSISTENT WITH FEDERAL, STATE, AND LOCAL REGULATIONS.

  8. Spatial gradient tuning in metamaterials

    Science.gov (United States)

    Driscoll, Tom; Goldflam, Michael; Jokerst, Nan; Basov, Dimitri; Smith, David

    2011-03-01

    Gradient Index (GRIN) metamaterials have been used to create devices inspired by, but often surpassing the potential of, conventional GRIN optics. The unit-cell nature of metamaterials presents the opportunity to exert much greater control over spatial gradients than is possible in natural materials. This is true not only during the design phase but also offers the potential for real-time reconfiguration of the metamaterial gradient. This ability fits nicely into the picture of transformation-optics, in which spatial gradients can enable an impressive suite of innovative devices. We discuss methods to exert control over metamaterial response, focusing on our recent demonstrations using Vanadium Dioxide. We give special attention to role of memristance and mem-capacitance observed in Vanadium Dioxide, which simplify the demands of stimuli and addressing, as well as intersecting metamaterials with the field of memory-materials.

  9. Effects of Population Growth and Climate Variability on Sustainable Groundwater in Mali, West Africa

    Directory of Open Access Journals (Sweden)

    Alexandra Lutz

    2010-12-01

    Full Text Available Groundwater is increasingly relied on as a source of potable water in developing countries, but factors such as population growth, development, and climate variability, pose potential challenges for ongoing sustainable supply. The effect of these factors on the groundwater system was considered in four scenarios using a numerical model to represent the Bani area of Mali, West Africa. By 2040, population growth, climate variability, and development as urbanization, agriculture, and industry creates scenarios in which groundwater extraction is an increasingly larger percentage of the groundwater system. Consumption from agriculture and industry increases extraction rates from less than 1 to 3.8% of mean annual precipitation, which will likely affect the groundwater system. For instance, concentrated pumping in local areas may result in water level declines. The results of this study contribute to an ongoing evaluation of sustainable groundwater resources in West Africa.

  10. The origin of high hydrocarbon groundwater in shallow Triassic aquifer in Northwest Guizhou, China.

    Science.gov (United States)

    Liu, Shan; Qi, Shihua; Luo, Zhaohui; Liu, Fangzhi; Ding, Yang; Huang, Huanfang; Chen, Zhihua; Cheng, Shenggao

    2018-02-01

    Original high hydrocarbon groundwater represents a kind of groundwater in which hydrocarbon concentration exceeds 0.05 mg/L. The original high hydrocarbon will significantly reduce the environment capacity of hydrocarbon and lead environmental problems. For the past 5 years, we have carried out for a long-term monitoring of groundwater in shallow Triassic aquifer in Northwest Guizhou, China. We found the concentration of petroleum hydrocarbon was always above 0.05 mg/L. The low-level anthropogenic contamination cannot produce high hydrocarbon groundwater in the area. By using hydrocarbon potential, geochemistry and biomarker characteristic in rocks and shallow groundwater, we carried out a comprehensive study in Dalongjing (DLJ) groundwater system to determine the hydrocarbon source. We found a simplex hydrogeology setting, high-level water-rock-hydrocarbon interaction and obviously original hydrocarbon groundwater in DLJ system. The concentration of petroleum hydrocarbon in shallow aquifer was found to increase with the strong water-rock interaction. Higher hydrocarbon potential was found in the upper of Guanling formation (T 2 g 3 ) and upper of Yongningzhen formation (T 1 yn 4 ). Heavily saturated carbon was observed from shallow groundwater, which presented similar distribution to those from rocks, especially from the deeper groundwater. These results indicated that the high concentrations of original hydrocarbon in groundwater could be due to the hydrocarbon release from corrosion and extraction out of strata over time.

  11. Low-gradient aortic stenosis.

    Science.gov (United States)

    Clavel, Marie-Annick; Magne, Julien; Pibarot, Philippe

    2016-09-07

    An important proportion of patients with aortic stenosis (AS) have a 'low-gradient' AS, i.e. a small aortic valve area (AVA gradient (gradient discrepancy raises uncertainty about the actual stenosis severity and thus about the indication for aortic valve replacement (AVR) if the patient has symptoms and/or left ventricular (LV) systolic dysfunction. The most frequent cause of low-gradient (LG) AS is the presence of a low LV outflow state, which may occur with reduced left ventricular ejection fraction (LVEF), i.e. classical low-flow, low-gradient (LF-LG), or preserved LVEF, i.e. paradoxical LF-LG. Furthermore, a substantial proportion of patients with AS may have a normal-flow, low-gradient (NF-LG) AS: i.e. a small AVA-low-gradient combination but with a normal flow. One of the most important clinical challenges in these three categories of patients with LG AS (classical LF-LG, paradoxical LF-LG, and NF-LG) is to differentiate a true-severe AS that generally benefits from AVR vs. a pseudo-severe AS that should be managed conservatively. A low-dose dobutamine stress echocardiography may be used for this purpose in patients with classical LF-LG AS, whereas aortic valve calcium scoring by multi-detector computed tomography is the preferred modality in those with paradoxical LF-LG or NF-LG AS. Although patients with LF-LG severe AS have worse outcomes than those with high-gradient AS following AVR, they nonetheless display an important survival benefit with this intervention. Some studies suggest that transcatheter AVR may be superior to surgical AVR in patients with LF-LG AS. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2016. For permissions please email: journals.permissions@oup.com.

  12. Arsenic levels in groundwater aquifer

    African Journals Online (AJOL)

    Miodrag Jelic

    resistance (ρ); dielectric constant (ε); magnetic permeability (η); electrochemical activity ..... comprises grey sands of different particle size distribution ..... groundwater: testing pollution mechanisms for sedimentary aquifers in. Bangladesh.

  13. Graded/Gradient Porous Biomaterials

    Directory of Open Access Journals (Sweden)

    Xigeng Miao

    2009-12-01

    Full Text Available Biomaterials include bioceramics, biometals, biopolymers and biocomposites and they play important roles in the replacement and regeneration of human tissues. However, dense bioceramics and dense biometals pose the problem of stress shielding due to their high Young’s moduli compared to those of bones. On the other hand, porous biomaterials exhibit the potential of bone ingrowth, which will depend on porous parameters such as pore size, pore interconnectivity, and porosity. Unfortunately, a highly porous biomaterial results in poor mechanical properties. To optimise the mechanical and the biological properties, porous biomaterials with graded/gradient porosity, pores size, and/or composition have been developed. Graded/gradient porous biomaterials have many advantages over graded/gradient dense biomaterials and uniform or homogenous porous biomaterials. The internal pore surfaces of graded/gradient porous biomaterials can be modified with organic, inorganic, or biological coatings and the internal pores themselves can also be filled with biocompatible and biodegradable materials or living cells. However, graded/gradient porous biomaterials are generally more difficult to fabricate than uniform or homogenous porous biomaterials. With the development of cost-effective processing techniques, graded/gradient porous biomaterials can find wide applications in bone defect filling, implant fixation, bone replacement, drug delivery, and tissue engineering.

  14. Recharge sources and hydrogeochemical evolution of groundwater in semiarid and karstic environments: A field study in the Granada Basin (Southern Spain)

    International Nuclear Information System (INIS)

    Kohfahl, Claus; Sprenger, Christoph; Herrera, Jose Benavente; Meyer, Hanno; Chacon, Franzisca Fernandez; Pekdeger, Asaf

    2008-01-01

    The objective of this study is to refine the understanding of recharge processes in watersheds representative for karstic semiarid areas by means of stable isotope analysis and hydrogeochemistry. The study focuses on the Granada aquifer system which is located in an intramontane basin bounded by high mountain ranges providing elevation differences of almost 2900 m. These altitude gradients lead to important temperature and precipitation gradients and provide excellent conditions for the application of stable isotopes of water whose composition depends mainly on temperature. Samples of rain, snow, surface water and groundwater were collected at 154 locations for stable isotope studies (δ 18 O, D) and, in the case of ground- and surface waters, also for major and minor ion analysis. Thirty-seven springs were sampled between 2 and 5 times from October 2004 to March 2005 along an altitudinal gradient from 552 masl in the Granada basin to 2156 masl in Sierra Nevada. Nine groundwater samples were taken from the discharge of operating wells in the Granada basin which are all located between 540 and 728 masl. The two main rivers were monitored every 2-3 weeks at three different altitudes. Rainfall being scarce during the sampling period, precipitation could only be sampled during four rainfall events. Calculated recharge altitudes of springs showed that source areas of mainly snowmelt recharge are generally located between 1600 and 2000 masl. The isotope compositions of spring water indicate water sources from the western Mediterranean as well as from the Atlantic without indicating a seasonal trend. The isotope pattern of the Quaternary aquifer reflects the spatial separation of different sources of recharge which occur mainly by bankfiltration of the main rivers. Isotopic signatures in the southeastern part of the aquifer indicate a considerable recharge contribution by subsurface flow discharged from the adjacent carbonate aquifer. No evaporation effects due to

  15. Recharge sources and hydrogeochemical evolution of groundwater in semiarid and karstic environments: A field study in the Granada Basin (Southern Spain)

    Energy Technology Data Exchange (ETDEWEB)

    Kohfahl, Claus [Freie Universitaet Berlin, Institute of Geological Sciences, Malteserstr. 74-100, D-12249 Berlin (Germany)], E-mail: kohfahl@zedat.fu-berlin.de; Sprenger, Christoph [Freie Universitaet Berlin, Institute of Geological Sciences, Malteserstr. 74-100, D-12249 Berlin (Germany); Herrera, Jose Benavente [Instituto del Agua de la Universidad de Granada, Ramon y Cajal, 4, 18071 Granada (Spain); Meyer, Hanno [Isotope Laboratory of the Alfred Wegener Institute for Polar and Marine Research, Research Unit Potsdam, Telegrafenberg A 43, 14473 Potsdam (Germany); Chacon, Franzisca Fernandez [Dpto. Hidrogeologia y Aguas Subterraneas, Instituto Geologico y Minero de Espana, Oficina de Proyectos, Urb. Alcazar del Genil 4, Edificio Zulema bajo, 18006 Granada (Spain); Pekdeger, Asaf [Freie Universitaet Berlin, Institute of Geological Sciences, Malteserstr. 74-100, D-12249 Berlin (Germany)

    2008-04-15

    The objective of this study is to refine the understanding of recharge processes in watersheds representative for karstic semiarid areas by means of stable isotope analysis and hydrogeochemistry. The study focuses on the Granada aquifer system which is located in an intramontane basin bounded by high mountain ranges providing elevation differences of almost 2900 m. These altitude gradients lead to important temperature and precipitation gradients and provide excellent conditions for the application of stable isotopes of water whose composition depends mainly on temperature. Samples of rain, snow, surface water and groundwater were collected at 154 locations for stable isotope studies ({delta}{sup 18}O, D) and, in the case of ground- and surface waters, also for major and minor ion analysis. Thirty-seven springs were sampled between 2 and 5 times from October 2004 to March 2005 along an altitudinal gradient from 552 masl in the Granada basin to 2156 masl in Sierra Nevada. Nine groundwater samples were taken from the discharge of operating wells in the Granada basin which are all located between 540 and 728 masl. The two main rivers were monitored every 2-3 weeks at three different altitudes. Rainfall being scarce during the sampling period, precipitation could only be sampled during four rainfall events. Calculated recharge altitudes of springs showed that source areas of mainly snowmelt recharge are generally located between 1600 and 2000 masl. The isotope compositions of spring water indicate water sources from the western Mediterranean as well as from the Atlantic without indicating a seasonal trend. The isotope pattern of the Quaternary aquifer reflects the spatial separation of different sources of recharge which occur mainly by bankfiltration of the main rivers. Isotopic signatures in the southeastern part of the aquifer indicate a considerable recharge contribution by subsurface flow discharged from the adjacent carbonate aquifer. No evaporation effects due

  16. Simulation of Groundwater Mounding Beneath Hypothetical Stormwater Infiltration Basins

    Science.gov (United States)

    Carleton, Glen B.

    2010-01-01

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

  17. Radioactivity in groundwater along the borders of Oman and UAE

    International Nuclear Information System (INIS)

    Murad, A.; Alshamsi, D.; Al Shidi, F.; Al Kendi, R.; Aldahan, A.; Uppsala University, Uppsala

    2014-01-01

    Characterizing the quality and radioactivity of groundwater is vital as it represents valuable resource in arid regions. Here we present radioactivity level in groundwater collected from wells in a region along the border between Sultanate of Oman and United Arab Emirates (UAE). The aquifers are alluvium deposits (silt, sand and gravel) and the measured groundwater radioactivity (including 232 Th, 238 U, 235 U, 226 Ra, 222 Rn, gross-α and gross-β) indicates values below the WHO permissible limits for drinking water. The results also show large difference in radioactivity fingerprints, in particular for 226 Ra and 222 Rn within the investigated aquifers. The data further indicate lower radioactivity in groundwater of the alluviums compared to the carbonate aquifers in the region. This feature makes the alluvium aquifers valuable reservoirs that should be carefully exploited as a source of groundwater. As this is the first investigation on the radioactivity of groundwater in alluvial aquifers in the region, it suggests that other alluvial deposits, particularly those inland and far from the marine water intrusion or seepage from carbonate rocks would have low radioactivity fingerprints. (author)

  18. Groundwater flux estimation in streams: A thermal equilibrium approach

    Science.gov (United States)

    Zhou, Yan; Fox, Garey A.; Miller, Ron B.; Mollenhauer, Robert; Brewer, Shannon

    2018-06-01

    Stream and groundwater interactions play an essential role in regulating flow, temperature, and water quality for stream ecosystems. Temperature gradients have been used to quantify vertical water movement in the streambed since the 1960s, but advancements in thermal methods are still possible. Seepage runs are a method commonly used to quantify exchange rates through a series of streamflow measurements but can be labor and time intensive. The objective of this study was to develop and evaluate a thermal equilibrium method as a technique for quantifying groundwater flux using monitored stream water temperature at a single point and readily available hydrological and atmospheric data. Our primary assumption was that stream water temperature at the monitored point was at thermal equilibrium with the combination of all heat transfer processes, including mixing with groundwater. By expanding the monitored stream point into a hypothetical, horizontal one-dimensional thermal modeling domain, we were able to simulate the thermal equilibrium achieved with known atmospheric variables at the point and quantify unknown groundwater flux by calibrating the model to the resulting temperature signature. Stream water temperatures were monitored at single points at nine streams in the Ozark Highland ecoregion and five reaches of the Kiamichi River to estimate groundwater fluxes using the thermal equilibrium method. When validated by comparison with seepage runs performed at the same time and reach, estimates from the two methods agreed with each other with an R2 of 0.94, a root mean squared error (RMSE) of 0.08 (m/d) and a Nash-Sutcliffe efficiency (NSE) of 0.93. In conclusion, the thermal equilibrium method was a suitable technique for quantifying groundwater flux with minimal cost and simple field installation given that suitable atmospheric and hydrological data were readily available.

  19. Groundwater discharge mapping by thermal infra-red imagery

    International Nuclear Information System (INIS)

    Brereton, N.R.

    1984-02-01

    An area around Altnabreac in northern Scotland has been studied as part of the UK programme of research into the feasibility of disposal of radioactive waste into geological formations. An essential prerequisite to being able to predict the behaviour, migratory pathways and travel times of radionuclides emanating from a waste repository is an understanding of the regional and near surface groundwater flow systems and groundwater geochemical evolution. The groundwater system at depth has been studied by means of boreholes but an understanding of the shallow groundwater flow, and its interaction with groundwater upwelling from depth, can be gained from studies of the spatial distribution and geochemistry of surface springs and discharges. A survey was carried out using the thermal infra-red linescan technique with the objective of locating all significant spring discharges over the study area. The terrain around Altnabreac is largely covered by superficial deposits which overlie weathered granite. The survey was carried out from a height of 275m at a spatial resolution of about 0.5m. About 280 line Km were covered but allowing for overlap between adjacent flight lines and some repeat coverage, the actual area surveyed was 68 sq Km. The most striking aspect of the results is the wide distribution of groundwater discharges in the Altnabreac area. An analysis of the data identified three general categories of spring and many of these springs were subsequently visited for verification and to allow samples to be collected for chemical analysis. The results from this survey indicates that the groundwater table is strongly influenced by local topography and that the majority of the spring discharges represent near surface recent groundwaters circulating within the superficial deposits and weathered granite

  20. Global simulation of interactions between groundwater and terrestrial ecosystems

    Science.gov (United States)

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

    2016-12-01

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

  1. Factor analytical approaches for evaluating groundwater trace element chemistry data

    International Nuclear Information System (INIS)

    Farnham, I.M.; Johannesson, K.H.; Singh, A.K.; Hodge, V.F.; Stetzenbach, K.J.

    2003-01-01

    The multivariate statistical techniques principal component analysis (PCA), Q-mode factor analysis (QFA), and correspondence analysis (CA) were applied to a dataset containing trace element concentrations in groundwater samples collected from a number of wells located downgradient from the potential nuclear waste repository at Yucca Mountain, Nevada. PCA results reflect the similarities in the concentrations of trace elements in the water samples resulting from different geochemical processes. QFA results reflect similarities in the trace element compositions, whereas CA reflects similarities in the trace elements that are dominant in the waters relative to all other groundwater samples included in the dataset. These differences are mainly due to the ways in which data are preprocessed by each of the three methods. The highly concentrated, and thus possibly more mature (i.e. older), groundwaters are separated from the more dilute waters using principal component 1 (PC 1). PC 2, as well as dimension 1 of the CA results, describe differences in the trace element chemistry of the groundwaters resulting from the different aquifer materials through which they have flowed. Groundwaters thought to be representative of those flowing through an aquifer composed dominantly of volcanic rocks are characterized by elevated concentrations of Li, Be, Ge, Rb, Cs, and Ba, whereas those associated with an aquifer dominated by carbonate rocks exhibit greater concentrations of Ti, Ni, Sr, Rh, and Bi. PC 3, and to a lesser extent dimension 2 of the CA results, show a strong monotonic relationship with the percentage of As(III) in the groundwater suggesting that these multivariate statistical results reflect, in a qualitative sense, the oxidizing/reducing conditions within the groundwater. Groundwaters that are relatively more reducing exhibit greater concentrations of Mn, Cs, Co, Ba, Rb, and Be, and those that are more oxidizing are characterized by greater concentrations of V, Cr, Ga

  2. 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 ...

  3. Tracer attenuation in groundwater

    Science.gov (United States)

    Cvetkovic, Vladimir

    2011-12-01

    The self-purifying capacity of aquifers strongly depends on the attenuation of waterborne contaminants, i.e., irreversible loss of contaminant mass on a given scale as a result of coupled transport and transformation processes. A general formulation of tracer attenuation in groundwater is presented. Basic sensitivities of attenuation to macrodispersion and retention are illustrated for a few typical retention mechanisms. Tracer recovery is suggested as an experimental proxy for attenuation. Unique experimental data of tracer recovery in crystalline rock compare favorably with the theoretical model that is based on diffusion-controlled retention. Non-Fickian hydrodynamic transport has potentially a large impact on field-scale attenuation of dissolved contaminants.

  4. Nitrate pollution of groundwater

    International Nuclear Information System (INIS)

    Heaton, T.H.E.

    1986-01-01

    Concern about the possible health risks associated with the consumption of nitrate has led many countries, including South Africa, to propose that 10mg of nitrogen (as nitrate or nitrite) per liter should be the maximum allowable limit for domestic water supplies. Groundwater in certain parts of South Africa and Namibia contains nitrate in concentrations which exceed this limit. The CSIR's Natural Isotope Division has been studying the nitrogen isotope composition of the nitrate as an aid to investigation into the sources of this nitrate contamination

  5. Shallow and Deep Groundwater Contributions to Ephemeral Streamflow Generation

    Science.gov (United States)

    Zimmer, M. A.; McGlynn, B. L.

    2016-12-01

    Our understanding of streamflow generation processes in low relief, humid landscapes is limited. To address this, we utilized an ephemeral-to-intermittent drainage network in the Piedmont region of the United States to gain new understanding about the drivers of ephemeral streamflow generation, stream-groundwater interactions, and longitudinal expansion and contraction of the stream network. We used hydrometric and chemical data collected within zero through second order catchments to characterize streamflow and overland, shallow soil, and deep subsurface flow across landscape positions. Results showed bi-directionality in stream-groundwater gradients that were dependent on catchment storage state. This led to annual groundwater recharge magnitudes that were similar to annual streamflow. Perched shallow and deep water table contributions shifted dominance with changes in catchment storage state, producing distinct stream hydrograph recession constants. Active channel length versus runoff followed a consistent relationship independent of storage state, but exhibited varying discharge-solute hysteresis directions. Together, our results suggest that temporary streams can act as both important groundwater recharge and discharge locations across the landscape, especially in this region where ephemeral drainage densities are among the highest recorded. Our results also highlight that the internal catchment dynamics that generate temporary streams play an important role in dictating biogeochemical fluxes at the landscape scale.

  6. Induced groundwater flux by increases in the aquifer's total stress.

    Science.gov (United States)

    Chang, Ching-Min; Yeh, Hund-Der

    2015-01-01

    Fluid-filled granular soils experience changes in total stress because of earth and oceanic tides, earthquakes, erosion, sedimentation, and changes in atmospheric pressure. The pore volume may deform in response to the changes in stress and this may lead to changes in pore fluid pressure. The transient fluid flow can therefore be induced by the gradient in excess pressure in a fluid-saturated porous medium. This work demonstrates the use of stochastic methodology in prediction of induced one-dimensional field-scale groundwater flow through a heterogeneous aquifer. A closed-form of mean groundwater flux is developed to quantify the induced field-scale mean behavior of groundwater flow and analyze the impacts of the spatial correlation length scale of log hydraulic conductivity and the pore compressibility. The findings provided here could be useful for the rational planning and management of groundwater resources in aquifers that contain lenses with large vertical aquifer matrix compressibility values. © 2014, National Ground Water Association.

  7. 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.

  8. Comparison of Coral Reef Ecosystems along a Fishing Pressure Gradient

    NARCIS (Netherlands)

    Weijerman, M.W.; Fulton, E.A.; Parrish, F.A.

    2013-01-01

    Three trophic mass-balance models representing coral reef ecosystems along a fishery gradient were compared to evaluate ecosystem effects of fishing. The majority of the biomass estimates came directly from a large-scale visual survey program; therefore, data were collected in the same way for all

  9. SR-Site - sulphide content in the groundwater at Forsmark

    Energy Technology Data Exchange (ETDEWEB)

    Tullborg, E-L (Terralogica (Sweden)); Smellie, J (Conterra (Sweden)); Nilsson, A-Ch (Geosigma (Sweden)); Gimeno, M J; Auque, LF (Univ. of Zaragoza (Spain)); Bruchert, V (Stockholms Universitet (Sweden)); Molinero, J (Amphos21 (Spain))

    2010-12-15

    Sulphide concentrations in groundwater play a key role in the long-term reliability of the metal canisters containing the radioactive waste within a disposal facility for nuclear waste. This is because sulphide in the groundwaters circulating in the vicinity of the deposition tunnels can react with copper in the canisters causing corrosion and therefore reducing their expected lifetime; in a worst case scenario erosion of the bentonite buffer material will expose the canister more rapidly to the fracture groundwater.Sulphide in the groundwater is predominantly microbially produced and thereby controlled by the content of oxidised sulphur sources, organics (carbon sources), reductants (mainly Fe(II), DOC, H{sub 2} and CH{sub 4}), and also flow and mixing of different groundwater types. In addition, achieved saturation in respect to amorphous Fe-monosulphide will control the possible maximum values and will also limit the Fe2+ and S2- values in the groundwater. The aim of this report is to assess realistic, representative and reliable sulphide groundwater concentrations at present conditions in Forsmark and also to evaluate possible changes during different climatic conditions covering the repository operation period (some tens to hundreds of years), post closure conditions (some thousand of years) and the proceeding temperate period (some tens of thousands of years) which may be extended due to enhanced greenhouse effects etc. It is expected that this period will be followed by the onset of the next glaciation during which periglacial (permafrost), glacial and postglacial conditions may succeed each other. To achieve these aims, an evaluation is performed of all the sulphide-related data reported from the Forsmark site investigations /Laaksoharju et al. 2008/ and later monitoring campaigns, all of which are stored in the Sicada database. This evaluation shows that values from the Complete Chemical Characterisation (CCC) sampling are usually lower than those measured

  10. SR-Site - sulphide content in the groundwater at Forsmark

    International Nuclear Information System (INIS)

    Tullborg, E-L; Smellie, J; Nilsson, A-Ch; Gimeno, M J; Auque, LF; Bruchert, V; Molinero, J

    2010-12-01

    Sulphide concentrations in groundwater play a key role in the long-term reliability of the metal canisters containing the radioactive waste within a disposal facility for nuclear waste. This is because sulphide in the groundwaters circulating in the vicinity of the deposition tunnels can react with copper in the canisters causing corrosion and therefore reducing their expected lifetime; in a worst case scenario erosion of the bentonite buffer material will expose the canister more rapidly to the fracture groundwater.Sulphide in the groundwater is predominantly microbially produced and thereby controlled by the content of oxidised sulphur sources, organics (carbon sources), reductants (mainly Fe(II), DOC, H 2 and CH 4 ), and also flow and mixing of different groundwater types. In addition, achieved saturation in respect to amorphous Fe-monosulphide will control the possible maximum values and will also limit the Fe 2+ and S 2- values in the groundwater. The aim of this report is to assess realistic, representative and reliable sulphide groundwater concentrations at present conditions in Forsmark and also to evaluate possible changes during different climatic conditions covering the repository operation period (some tens to hundreds of years), post closure conditions (some thousand of years) and the proceeding temperate period (some tens of thousands of years) which may be extended due to enhanced greenhouse effects etc. It is expected that this period will be followed by the onset of the next glaciation during which periglacial (permafrost), glacial and postglacial conditions may succeed each other. To achieve these aims, an evaluation is performed of all the sulphide-related data reported from the Forsmark site investigations /Laaksoharju et al. 2008/ and later monitoring campaigns, all of which are stored in the Sicada database. This evaluation shows that values from the Complete Chemical Characterisation (CCC) sampling are usually lower than those measured during

  11. Sustainable groundwater management in California

    Science.gov (United States)

    Phillips, Steven P.; Rogers, Laurel Lynn; Faunt, Claudia

    2015-12-01

    The U.S. Geological Survey (USGS) uses data collection, modeling tools, and scientific analysis to help water managers plan for, and assess, hydrologic issues that can cause “undesirable results” associated with groundwater use. This information helps managers understand trends and investigate and predict effects of different groundwater-management strategies.

  12. Groundwater protection management program plan

    International Nuclear Information System (INIS)

    1992-06-01

    US Department of Energy (DOE) Order 5400.1 requires the establishment of a groundwater protection management program to ensure compliance with DOE requirements and applicable Federal, state, and local laws and regulations. The Uranium Mill Tailings Remedial Action (UMTRA) Project Office has prepared a ''Groundwater Protection Management Program Plan'' (groundwater protection plan) of sufficient scope and detail to reflect the program's significance and address the seven activities required in DOE Order 5400.1, Chapter 3, for special program planning. The groundwater protection plan highlights the methods designed to preserve, protect, and monitor groundwater resources at UMTRA Project processing and disposal sites. The plan includes an overview of the remedial action status at the 24 designated processing sites and identifies project technical guidance documents and site-specific documents for the UMTRA groundwater protection management program. In addition, the groundwater protection plan addresses the general information required to develop a water resources protection strategy at the permanent disposal sites. Finally, the plan describes ongoing activities that are in various stages of development at UMTRA sites (long-term care at disposal sites and groundwater restoration at processing sites). This plan will be reviewed annually and updated every 3 years in accordance with DOE Order 5400.1

  13. Hanford Sitewide Groundwater Remediation Strategy

    International Nuclear Information System (INIS)

    Knepp, A.J.; Isaacs, J.D.

    1997-09-01

    This document fulfills the requirements of the Hanford Federal Facility Agreement and Consent Order, Milestone M-13-81, to develop a concise statement of strategy that describe show the Hanford Site groundwater remediation will be accomplished. The strategy addresses objectives and goals, prioritization of activities, and technical approaches for groundwater cleanup. The strategy establishes that the overall goal of groundwater remediation on the Hanford Site is to restore groundwater to its beneficial uses in terms of protecting human health and the environment, and its use as a natural resource. The Hanford Future Site Uses Working Group established two categories for groundwater commensurate with various proposed landuses: (1) restricted use or access to groundwater in the Central Plateau and in a buffer zone surrounding it and (2) unrestricted use or access to groundwater for all other areas. In recognition of the Hanford Future Site Uses Working Group and public values, the strategy establishes that the sitewide approach to groundwater cleanup is to remediate the major plumes found in the reactor areas that enter the Columbia River and to contain the spread and reduce the mass of the major plumes found in the Central Plateau

  14. Isotope hydrology: Investigating groundwater contamination

    International Nuclear Information System (INIS)

    Dubinchuk, V.; Froehlich, K.; Gonfiantini, R.

    1989-01-01

    Groundwater quality has worsened in many regions, with sometimes serious consequences. Decontaminating groundwater is an extremely slow process, and sometimes impossible, because of the generally long residence time of the water in most geological formations. Major causes of contamination are poor groundwater management (often dictated by immediate social needs) and the lack of regulations and control over the use and disposal of contaminants. These types of problems have prompted an increasing demand for investigations directed at gaining insight into the behaviour of contaminants in the hydrological cycle. Major objectives are to prevent pollution and degradation of groundwater resources, or, if contamination already has occurred, to identify its origin so that remedies can be proposed. Environmental isotopes have proved to be a powerful tool for groundwater pollution studies. The IAEA has had a co-ordinated research programme since 1987 on the application of nuclear techniques to determine the transport of contaminants in groundwater. An isotope hydrology project is being launched within the framework of the IAEA's regional co-operative programme in Latin America (known as ARCAL). Main objectives are the application of environmental isotopes to problems of groundwater assessment and contamination in Latin America. In 1989, another co-ordinated research programme is planned under which isotopic and other tracers will be used for the validation of mathematical models in groundwater transport studies

  15. Technical approach to groundwater restoration

    International Nuclear Information System (INIS)

    1993-01-01

    The Technical Approach to Groundwater Restoration (TAGR) provides general technical guidance to implement the groundwater restoration phase of the Uranium Mill Tailings Remedial Action (UMTRA) Project. The TAGR includes a brief overview of the surface remediation and groundwater restoration phases of the UMTRA Project and describes the regulatory requirements, the National Environmental Policy Act (NEPA) process, and regulatory compliance. A section on program strategy discusses program optimization, the role of risk assessment, the observational approach, strategies for meeting groundwater cleanup standards, and remedial action decision-making. A section on data requirements for groundwater restoration evaluates the data quality objectives (DQO) and minimum data required to implement the options and comply with the standards. A section on sits implementation explores the development of a conceptual site model, approaches to site characterization, development of remedial action alternatives, selection of the groundwater restoration method, and remedial design and implementation in the context of site-specific documentation in the site observational work plan (SOWP) and the remedial action plan (RAP). Finally, the TAGR elaborates on groundwater monitoring necessary to evaluate compliance with the groundwater cleanup standards and protection of human health and the environment, and outlines licensing procedures

  16. 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

  17. Rapid Gradient-Echo Imaging

    Science.gov (United States)

    Hargreaves, Brian

    2012-01-01

    Gradient echo sequences are widely used in magnetic resonance imaging (MRI) for numerous applications ranging from angiography to perfusion to functional MRI. Compared with spin-echo techniques, the very short repetition times of gradient-echo methods enable very rapid 2D and 3D imaging, but also lead to complicated “steady states.” Signal and contrast behavior can be described graphically and mathematically, and depends strongly on the type of spoiling: fully balanced (no spoiling), gradient spoiling, or RF-spoiling. These spoiling options trade off between high signal and pure T1 contrast while the flip angle also affects image contrast in all cases, both of which can be demonstrated theoretically and in image examples. As with spin-echo sequences, magnetization preparation can be added to gradient-echo sequences to alter image contrast. Gradient echo sequences are widely used for numerous applications such as 3D perfusion imaging, functional MRI, cardiac imaging and MR angiography. PMID:23097185

  18. The influence of ALN-Al gradient material gradient index on ballistic performance

    International Nuclear Information System (INIS)

    Wang Youcong; Liu Qiwen; Li Yao; Shen Qiang

    2013-01-01

    Ballistic performance of the gradient material is superior to laminated material, and gradient materials have different gradient types. Using ls-dyna to simulate the ballistic performance of ALN-AL gradient target plates which contain three gradient index (b = 1, b = 0.5, b = 2). Through Hopkinson bar numerical simulation to the target plate materials, we obtained the reflection stress wave and transmission stress wave state of gradient material to get the best gradient index. The internal stress state of gradient material is simulated by amplification processing of the target plate model. When the gradient index b is equal to 1, the gradient target plate is best of all.

  19. 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.

  20. Budgets and chemical characterization of groundwater for the Diamond Valley flow system, central Nevada, 2011–12

    Science.gov (United States)

    Berger, David L.; Mayers, C. Justin; Garcia, C. Amanda; Buto, Susan G.; Huntington, Jena M.

    2016-07-29

    The Diamond Valley flow system consists of six hydraulically connected hydrographic areas in central Nevada. The general down-gradient order of the areas are southern and northern Monitor Valleys, Antelope Valley, Kobeh Valley, Stevens Basin, and Diamond Valley. Groundwater flow in the Diamond Valley flow system terminates at a large playa in the northern part of Diamond Valley. Concerns relating to continued water-resources development of the flow system resulted in a phased hydrologic investigation that began in 2005 by the U.S. Geological Survey in cooperation with Eureka County. This report presents the culmination of the phased investigation to increase understanding of the groundwater resources of the basin-fill aquifers in the Diamond Valley flow system through evaluations of groundwater chemistry and budgets. Groundwater chemistry was characterized using major ions and stable isotopes from groundwater and precipitation samples. Groundwater budgets accounted for all inflows, outflows, and changes in storage, and were developed for pre-development (pre-1950) and recent (average annual 2011–12) conditions. Major budget components include groundwater discharge by evapotranspiration and groundwater withdrawals; groundwater recharge by precipitation, and interbasin flow; and storage change.

  1. The thermal consequences of river-level variations in an urban groundwater body highly affected by groundwater heat pumps.

    Science.gov (United States)

    García-Gil, Alejandro; Vázquez-Suñe, Enric; Schneider, Eduardo Garrido; Sánchez-Navarro, José Ángel; Mateo-Lázaro, Jesús

    2014-07-01

    The extensive implementation of ground source heat pumps in urban aquifers is an important issue related to groundwater quality and the future economic feasibility of existent geothermal installations. Although many cities are in the immediate vicinity of large rivers, little is known about the thermal river-groundwater interaction at a kilometric-scale. The aim of this work is to evaluate the thermal impact of river water recharges induced by flood events into an urban alluvial aquifer anthropogenically influenced by geothermal exploitations. The present thermal state of an urban aquifer at a regional scale, including 27 groundwater heat pump installations, has been evaluated. The thermal impacts of these installations in the aquifer together with the thermal impacts from "cold" winter floods have also been spatially and temporally evaluated to ensure better geothermal management of the aquifer. The results showed a variable direct thermal impact from 0 to 6 °C depending on the groundwater-surface water interaction along the river trajectory. The thermal plumes far away from the riverbed also present minor indirect thermal impacts due to hydraulic gradient variations. Copyright © 2014 Elsevier B.V. All rights reserved.

  2. Tritium as tracer of groundwater pollution extension: case study of Andralanitra landfill site, Antananarivo-Madagascar

    Science.gov (United States)

    Ramaroson, Voahirana; Rakotomalala, Christian Ulrich; Rajaobelison, Joel; Fareze, Lahimamy Paul; Razafitsalama, Falintsoa A.; Rasolofonirina, Mamiseheno

    2018-05-01

    This study aims to understand the extension of groundwater pollution downstream of a landfill, Andralanitra-Antananarivo-Madagascar. Twenty-one samples, composed of dug well waters, spring waters, river, and lake, were measured in stable isotopes ( δ 2H, δ 18O) and tritium. Results showed that only two dug well waters, collected at the immediate vicinity of the landfill, have high tritium activities (22.82 TU and 10.43 TU), probably of artificial origin. Both upstream and further downstream of the landfill, tritium activities represent natural source, with values varying from 0.17 TU to 1.46 TU upstream and from 0.88 TU to 1.88 TU further downstream. Stable isotope data suggest that recharge occurs through infiltration of slightly evaporated rainfall. Using the radioactive decay equation, the calculated tracer ages related to two recent ground water samples collected down gradient of the landfill lay between [8-15] years and [4-7] years, taking into account the uncertainty of tritium measurements. For the calculation, a value of 2.36 TU was taken as A o. The latter was estimated based on similarity between stable isotope compositions of nearby spring and dug well waters as well as tritium activities of the local precipitation. Calculation of the tritium activities from the contaminated water point having 22.82 TU to further downstream using the calculated tracer ages showed values of one order of magnitude higher than the measured values. The absence of hydrological connection from the contaminated water point to further downstream the landfill would explain the lower tritium activities measured. Groundwater pollution seems to be limited to the closest proximity of the landfill.

  3. Preliminary uncertainty analysis of pre-waste-emplacement groundwater travel times for a proposed repository in basalt

    International Nuclear Information System (INIS)

    Clifton, P.M.; Arnett, R.C.

    1984-01-01

    Preliminary uncertainty analyses of pre-waste-emplacement groundwater travel times are presented for a potential high-level nuclear waste repository in the deep basalts beneath the Hanford Site, Washington State. The uncertainty analyses are carried out by means of a Monte Carlo technique, which requires the uncertain inputs to be described as either random variables or spatial stochastic processes. Pre-waste-emplacement groundwater travel times are modeled in a continuous, flat-lying basalt flow top that is assumed to overlie the repository horizon. Two-dimensional, steady state groundwater flow is assumed, and transmissivity, effective thickness, and regional hydraulic gradient are considered as uncertain inputs. Groundwater travel time distributions corresponding to three groundwater models are presented and compared. Limitations of these preliminary simulation results are discussed in detail

  4. 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.

  5. Radon as an indicator of submarine groundwater discharge in coastal regions

    International Nuclear Information System (INIS)

    Jacob, Noble; Shivanna, K.; Suresh Babu, D.S.

    2009-01-01

    This article reviews the various available methodologies to estimate submarine groundwater discharge (SGD) and demonstrates the utility of radon with a case study. An attempt has been made to identify the existence of submarine groundwater discharge (SGD) and semi-quantitatively estimate its rate in the coastal area of Vizhinjam, Thiruvananthapuram, Kerala. Natural 222 Rn (half-life = 3.8 days) was used as a tracer of SGD because of its conservative nature, short half-life, easiness in measurement and high abundance in groundwater. As in situ radon ( 222 Rn) monitoring study conducted in this region indicated comparatively higher 222 Rn activities (average 14.1±1.7 Bq/m 3 ) in the coastal waters revealing significant submarine groundwater discharge. The SGD may be a combination of fresh groundwater and recirculated seawater that is controlled by the hydraulic gradient in the adjacent aquifer and varying tidal conditions in the coastal waters. Using a transient 222 Rn mass balance model for the coastal waters, SGD rates were computed and the average value was found to be 10.9±6.1 cm/day. These estimates are comparable with those reported in the literature. In general, identification and estimation of submarine groundwater discharge is important in the Indian context because of the possibility of large amounts of groundwater loss through its long coastline, that can be judiciously exploited to cater to the present water requirements for drinking and irrigation purposes. (author)

  6. 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

  7. Gradient-based model calibration with proxy-model assistance

    Science.gov (United States)

    Burrows, Wesley; Doherty, John

    2016-02-01

    Use of a proxy model in gradient-based calibration and uncertainty analysis of a complex groundwater model with large run times and problematic numerical behaviour is described. The methodology is general, and can be used with models of all types. The proxy model is based on a series of analytical functions that link all model outputs used in the calibration process to all parameters requiring estimation. In enforcing history-matching constraints during the calibration and post-calibration uncertainty analysis processes, the proxy model is run for the purposes of populating the Jacobian matrix, while the original model is run when testing parameter upgrades; the latter process is readily parallelized. Use of a proxy model in this fashion dramatically reduces the computational burden of complex model calibration and uncertainty analysis. At the same time, the effect of model numerical misbehaviour on calculation of local gradients is mitigated, this allowing access to the benefits of gradient-based analysis where lack of integrity in finite-difference derivatives calculation would otherwise have impeded such access. Construction of a proxy model, and its subsequent use in calibration of a complex model, and in analysing the uncertainties of predictions made by that model, is implemented in the PEST suite.

  8. Numerical modeling of solute transport in a sand tank physical model under varying hydraulic gradient and hydrological stresses

    Science.gov (United States)

    Atlabachew, Abunu; Shu, Longcang; Wu, Peipeng; Zhang, Yongjie; Xu, Yang

    2018-03-01

    This laboratory study improves the understanding of the impacts of horizontal hydraulic gradient, artificial recharge, and groundwater pumping on solute transport through aquifers. Nine experiments and numerical simulations were carried out using a sand tank. The variable-density groundwater flow and sodium chloride transport were simulated using the three-dimensional numerical model SEAWAT. Numerical modelling results successfully reproduced heads and concentrations observed in the sand tank. A higher horizontal hydraulic gradient enhanced the migration of sodium chloride, particularly in the groundwater flow direction. The application of constant artificial recharge increased the spread of the sodium chloride plume in both the longitudinal and lateral directions. In addition, groundwater pumping accelerated spreading of the sodium chloride plume towards the pumping well. Both higher hydraulic gradient and pumping rate generated oval-shaped plumes in the horizontal plane. However, the artificial recharge process produced stretched plumes. These effects of artificial recharge and groundwater pumping were greater under higher hydraulic gradient. The concentration breakthrough curves indicated that emerging solutions never attained the concentration of the originally injected solution. This is probably because of sorption of sodium chloride onto the silica sand and/or the exchange of sodium chloride between the mobile and immobile liquid domains. The fingering and protruding plume shapes in the numerical models constitute instability zones produced by buoyancy-driven flow. Overall, the results have substantiated the influences of hydraulic gradient, boundary condition, artificial recharge, pumping rate and density differences on solute transport through a homogeneous unconfined aquifer. The implications of these findings are important for managing liquid wastes.

  9. Groundwater: from mystery to management

    International Nuclear Information System (INIS)

    Narasimhan, T N

    2009-01-01

    Groundwater has been used for domestic and irrigation needs from time immemorial. Yet its nature and occurrence have always possessed a certain mystery because water below the land surface is invisible and relatively inaccessible. The influence of this mystery lingers in some tenets that govern groundwater law. With the birth of modern geology during the late nineteenth century, groundwater science became recognized in its own right. Over the past two centuries, groundwater has lost its shroud of mystery, and its scientific understanding has gradually grown hand-in-hand with its development for human use. Groundwater is a component of the hydrological cycle, vital for human sustenance. Its annual renewability from precipitation is limited, and its chemical quality is vulnerable to degradation by human action. In many parts of the world, groundwater extraction is known to greatly exceed its renewability. Consequently, its rational management to benefit present and future generations is a matter of deep concern for many nations. Groundwater management is a challenging venture, requiring an integration of scientific knowledge with communal will to adapt to constraints of a finite common resource. As scientists and policy makers grapple with the tasks of groundwater management, it is instructive to reflect on the evolution of groundwater knowledge from its initial phase of demystification at the beginning of the nineteenth century, through successive phases of technological conquest, scientific integration, discovery of unintended consequences and the present recognition of an imperative for judicious management. The following retrospective provides a broad context for unifying the technical contributions that make up this focus issue on groundwater resources, climate and vulnerability.

  10. 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.)

  11. Radon as a groundwater tracer in Forsmark and Laxemar

    Energy Technology Data Exchange (ETDEWEB)

    Grolander, Sara

    2009-10-15

    caused by the homogenous radon concentrations measured in the Laxemar area. The radon concentrations in near surface water measured in Forsmark showed large variability with both low and high radon concentrations. This large variability in radon concentration could not be explained by the flow pattern of the groundwater since no clear correlation between radon concentration and recharge/discharge classification was found. The radon concentration was also measured at different depths in the soil profile at three locations in the Forsmark area. The results showed large differences with increasing radon concentration with increasing depth. This gradient of radon concentration can be explained largely by the radon emanation potential of the local soil type at different depths. High radon concentrations were found in wells with higher radon emanation potential like till and bedrock. These observations showed the importance of the radon emanation potential of the local soil for the radon concentration in groundwater. The main purpose of this study has been to evaluate the use of radon as a tracer for groundwater flow patterns. The method is based on the ingrowth of radon from its progenitor radium according to the law of radioactive decay. According to this law the radon concentration in groundwater will reach equilibrium conditions after approximately 30 days in contact with the surrounding soil. The equilibrium radon concentration of the near surface groundwater was measured at several location in the Forsmark area and a range of the steady state radon concentration was calculated. The measured steady state radon concentration was then used to evaluate the radon concentrations measured in near surface groundwater in the area. A recharge/discharge classification of the wells was done based on the range of steady state radon concentration and the measured radon concentrations in groundwater. All wells with radon concentration below the steady state radon concentration were

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

    Science.gov (United States)

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

    2014-03-01

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

  13. What Controls Submarine Groundwater Discharge?

    Science.gov (United States)

    Martin, J. B.; Cable, J. E.; Cherrier, J.; Roy, M.; Smith, C. G.; Dorsett, A.

    2008-05-01

    Numerous processes have been implicated in controlling submarine groundwater discharge (SGD) to coastal zones since Ghyben, Herzberg and Dupuit developed models of fresh water discharge from coastal aquifers at the turn of the 19th century. Multiple empirical and modeling techniques have also been applied to these environments to measure the flow. By the mid-1950's, Cooper had demonstrated that dispersion across the fresh water-salt water boundary required salt water entrained into fresh water flow be balanced by recharge of salt water across the sediment-water interface seaward of the outflow face. Percolation of water into the beach face from wind and tidal wave run up and changes in pressure at the sediment-water interface with fluctuating tides have now been recognized, and observed, as processes driving seawater into the sediments. Within the past few years, variations in water table levels and the 1:40 amplification from density difference in fresh water and seawater have been implicated to pump salt water seasonally across the sediment- water interface. Salt water driven by waves, tides and seasonal water table fluctuations is now recognized as a component of SGD when it flows back to overlying surface waters. None of these processes are sufficiently large to provide measured volumes of SGD in Indian River Lagoon, Florida, however, because minimal tides and waves exist, flat topography and transmissive aquifers minimize fluctuations of the water table, and little water is entrained across the salt water-fresh water boundary. Nonetheless, the saline fraction of SGD represents more than 99% of the volume of total SGD in the Indian River Lagoon. This volume of saline SGD can be driven by the abundance of burrowing organisms in the lagoon, which pump sufficient amounts of water through the sediment- water interface. These bioirrigating organisms are ubiquitous at all water depths in sandy sediment and thus may provide one of the major sources of SGD world wide

  14. Assessing potential effects of changes in water use with a numerical groundwater-flow model of Carson Valley, Douglas County, Nevada, and Alpine County, California

    Science.gov (United States)

    Yager, Richard M.; Maurer, Douglas K.; Mayers, C.J.

    2012-01-01

    Rapid growth and development within Carson Valley in Douglas County, Nevada, and Alpine County, California, has caused concern over the continued availability of groundwater, and whether the increased municipal demand could either impact the availability of water or result in decreased flow in the Carson River. Annual pumpage of groundwater has increased from less than 10,000 acre feet per year (acre-ft/yr) in the 1970s to about 31,000 acre-ft/yr in 2004, with most of the water used in agriculture. Municipal use of groundwater totaled about 10,000 acre-feet in 2000. In comparison, average streamflow entering the valley from 1940 to 2006 was 344,100 acre-ft/yr, while average flow exiting the valley was 297,400 acre-ft/yr. Carson Valley is underlain by semi-consolidated Tertiary sediments that are exposed on the eastern side and dip westward. Quaternary fluvial and alluvial deposits overlie the Tertiary sediments in the center and western side of the valley. The hydrology of Carson Valley is dominated by the Carson River, which supplies irrigation water for about 39,000 acres of farmland and maintains the water table less than 5 feet (ft) beneath much of the valley floor. Perennial and ephemeral watersheds drain the Carson Range and the Pine Nut Mountains, and mountain-front recharge to the groundwater system from these watersheds is estimated to average 36,000 acre-ft/yr. Groundwater in Carson Valley flows toward the Carson River and north toward the outlet of the Carson Valley. An upward hydraulic gradient exists over much of the valley, and artesian wells flow at land surface in some areas. Water levels declined as much as 15 ft since 1980 in some areas on the eastern side of the valley. Median estimated transmissivities of Quaternary alluvial-fan and fluvial sediments, and Tertiary sediments are 316; 3,120; and 110 feet squared per day (ft2/d), respectively, with larger transmissivity values in the central part of the valley and smaller values near the valley

  15. ZVI-Clay remediation of a chlorinated solvent source zone, Skuldelev, Denmark: 2. Groundwater contaminant mass discharge reduction

    DEFF Research Database (Denmark)

    Fjordbøge, Annika Sidelmann; Lange, Ida Vedel; Bjerg, Poul Løgstrup

    2012-01-01

    The impact of source mass depletion on the down-gradient contaminant mass discharge was monitored for a 19-month period as a part of a field demonstration of the ZVI-Clay soil mixing remediation technology. Groundwater samples were collected from conventional monitoring wells (120 samples) and a ...... down-gradient contaminant mass discharge reduction (76%) for the parent compound (PCE), while the overall reduction of chlorinated ethenes was smaller (21%)....

  16. Climate change impact on shallow groundwater conditions in Hungary: Conclusions from a regional modelling study

    Science.gov (United States)

    Kovács, Attila; Marton, Annamária; Tóth, György; Szöcs, Teodóra

    2016-04-01

    A quantitative methodology has been developed for the calculation of groundwater table based on measured and simulated climate parameters. The aim of the study was to develop a toolset which can be used for the calculation of shallow groundwater conditions for various climate scenarios. This was done with the goal of facilitating the assessment of climate impact and vulnerability of shallow groundwater resources. The simulated groundwater table distributions are representative of groundwater conditions at the regional scale. The introduced methodology is valid for modelling purposes at various scales and thus represents a versatile tool for the assessment of climate vulnerability of shallow groundwater bodies. The calculation modules include the following: 1. A toolset to calculate climate zonation from climate parameter grids, 2. Delineation of recharge zones (Hydrological Response Units, HRUs) based on geology, landuse and slope conditions, 3. Calculation of percolation (recharge) rates using 1D analytical hydrological models, 4. Simulation of the groundwater table using numerical groundwater flow models. The applied methodology provides a quantitative link between climate conditions and shallow groundwater conditions, and thus can be used for assessing climate impacts. The climate data source applied in our calculation comprised interpolated daily climate data of the Central European CARPATCLIM database. Climate zones were determined making use of the Thorntwaite climate zonation scheme. Recharge zones (HRUs) were determined based on surface geology, landuse and slope conditions. The HELP hydrological model was used for the calculation of 1D water balance for hydrological response units. The MODFLOW numerical groundwater modelling code was used for the calculation of the water table. The developed methodology was demonstrated through the simulation of regional groundwater table using spatially averaged climate data and hydrogeological properties for various time

  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. Bateman gradients in hermaphrodites: An extended approach to quantify sexual selection.

    NARCIS (Netherlands)

    Anthes, N.; David, P.; Auld, J.R.; Hoffer, J.N.A.; Jarne, P.; Koene, J.M.; Kokko, H.; Lorenzi, M.C.; Pélissié, B.; Sprenger, D.; Staikou, A.; Schärer, L.

    2011-01-01

    Sexual selection is often quantified using Bateman gradients, which represent sex-specific regression slopes of reproductive success on mating success and thus describe the expected fitness returns from mating more often. Although the analytical framework for Bateman gradients aimed at covering all

  19. Socioeconomic Gradients and Child Development in a Very Low Income Population: Evidence from Madagascar

    Science.gov (United States)

    Fernald, Lia C. H.; Weber, Ann; Galasso, Emanuela; Ratsifandrihamanana, Lisy

    2011-01-01

    Our objectives were to document and examine socioeconomic gradients across a comprehensive set of child development measures in a population living in extreme poverty, and to interpret these gradients in light of findings from the neuroscience literature. We assessed a nationally representative sample of 3-6-year-old children (n = 1332) from 150…

  20. New and noteworthy bird records from the Mt. Wilhelm elevational gradient, Papua New Guinea

    DEFF Research Database (Denmark)

    Marki, Petter Zahl; Sam, Katerina; Koane, Bonny

    2016-01-01

    The elevational gradient of Mt. Wilhelm, the highest peak in Papua New Guinea, represents one of the best-surveyed elevational gradients in the Indo-Pacific region. Based on field work undertaken in 2013 and 2015, we report range extensions, new elevational records and add 24 species to the list...

  1. A study of gradient strengthening based on a finite-deformation gradient crystal-plasticity model

    Science.gov (United States)

    Pouriayevali, Habib; Xu, Bai-Xiang

    2017-11-01

    A comprehensive study on a finite-deformation gradient crystal-plasticity model which has been derived based on Gurtin's framework (Int J Plast 24:702-725, 2008) is carried out here. This systematic investigation on the different roles of governing components of the model represents the strength of this framework in the prediction of a wide range of hardening behaviors as well as rate-dependent and scale-variation responses in a single crystal. The model is represented in the reference configuration for the purpose of numerical implementation and then implemented in the FEM software ABAQUS via a user-defined subroutine (UEL). Furthermore, a function of accumulation rates of dislocations is employed and viewed as a measure of formation of short-range interactions. Our simulation results reveal that the dissipative gradient strengthening can be identified as a source of isotropic-hardening behavior, which may represent the effect of irrecoverable work introduced by Gurtin and Ohno (J Mech Phys Solids 59:320-343, 2011). Here, the variation of size dependency at different magnitude of a rate-sensitivity parameter is also discussed. Moreover, an observation of effect of a distinctive feature in the model which explains the effect of distortion of crystal lattice in the reference configuration is reported in this study for the first time. In addition, plastic flows in predefined slip systems and expansion of accumulation of GNDs are distinctly observed in varying scales and under different loading conditions.

  2. Mapping groundwater renewability using age data in the Baiyang alluvial fan, NW China

    Science.gov (United States)

    Huang, Tianming; Pang, Zhonghe; Li, Jie; Xiang, Yong; Zhao, Zhijiang

    2017-05-01

    Groundwater age has been used to map renewability of water resources within four groups: strong, partial, and rare renewability, and non-renewable. The Baiyang alluvial fan in NW China is a representative area for examining groundwater recharge from river infiltration and for mapping groundwater renewability, and it has been investigated using multiple isotopes and water chemistry. Systematic sampling included 52 samples for 2H and 18O analysis and 32 samples for 3H, 13C and 14C analysis. The δ13C compositions remain nearly constant throughout the basin (median -12.7‰) and indicate that carbonate dissolution does not alter 14C age. The initial 14C activity of 80 pmC, obtained by plotting 3H and 14C activity, was used to correct groundwater 14C age. The results show that areas closer to the river consist of younger groundwater ages; this suggests that river infiltration is the main recharge source to the shallow groundwater system. However, at distances far away from the river, groundwater ages become older, i.e., from modern water (less than 60 year) to pre-modern water (from 60 to 1,000 years) and paleowater (more than 1,000 yeas). The four classifications of groundwater renewability have been associated with different age ranges. The area of shallow groundwater with strong renewability accounts for 74% of the total study area. Because recharge condition (river infiltration) controls overall renewability, a groundwater renewability map is of significant importance to the management of groundwater exploitation of this area as well as other arid groundwater basins.

  3. Water use and groundwater contamination

    International Nuclear Information System (INIS)

    Elton, J.J.; Livingstone, B.

    1998-01-01

    A general review of the groundwater resources in Saskatchewan and their vulnerability to contamination was provided. In particular, the use of water and the effects on water by the oil and gas industry in Saskatchewan were discussed. It was suggested that public concerns over scarcity and contamination of water are gradually changing perceptions about Canada's abundance of water. Saskatchewan's surface water covers 12 per cent of the province. About 90 per cent of the rural populations and 80 per cent of municipalities depend on groundwater supplies. Regulations affecting oil and gas operations that could affect water resources have become more stringent. Techniques used in the detection and monitoring of groundwater affected by salt and petroleum hydrocarbons were described. Electromagnetic surveys are used in detecting salt-affected soils and groundwater. Laboratory analysis of chloride concentrations are needed to define actual chloride concentrations in groundwater. Wells and barriers can be installed to control and recover chloride plumes. Deep well injection and reverse osmosis are other methods, but there is no cheap or simple treatment or disposal method for salt-impacted groundwater. Spills or leaks of petroleum hydrocarbons from various sources can also lead to contamination of groundwater. Various assessment and remediation methods are described. Although there is no scarcity of techniques, all of them are difficult, costly, and may take several years to complete. 11 refs., 1 tab

  4. Characterization of colloids in groundwater

    International Nuclear Information System (INIS)

    Kim, J.I.; Buckau, G.; Klenze, R.

    1987-07-01

    Natural colloids in the Gorleben aquifer systems have been investigated as for their chemical composition, quantification and size distribution. Humic substances appear to be the major organic materials in these groundwaters, generating humic colloids which are analysed to be humic acid (and fulvic acid) loaded with a large number of trace heavy metal ions. These metal ions include natural homologues of actinides and some fission products in trivalent, tetravalent and hexavalent state. Concentrations of trivalent and tetravalent heavy metal ions are linearly correlated with the dissolved organic carbon (DDC) concentration in different groundwaters. The DOC is found to be present as humic colloids. The Am 3+ ions introduced in such a groundwater readily undergo the generation of its pseudocolloids through sorption or ion exchange reactions with humic colloids. The chemical behaviour of Am(III), being similar to the trivalent metal ions, e.g. Fe 3+ , REE etc. found in natural colloids, has been investigated by laser induced photoacoustic spectroscopy (LPAS). Groundwaters from Ispra, Markham Clinton and Felslabor Grimsel. Bidistilled water and one of Gorleben groundwaters, Gohy 1011, are taken for the purpose of comparison. This groundwater contains the least amount of natural colloids of all Gorleben groundwaters hitherto investigated. An indirect quantification is made by comparison of the LPAS results with experiment from Latex solution. (orig./IRB)

  5. Calculation of groundwater travel time

    International Nuclear Information System (INIS)

    Arnett, R.C.; Sagar, B.; Baca, R.G.

    1984-12-01

    Pre-waste-emplacement groundwater travel time is one indicator of the isolation capability of the geologic system surrounding a repository. Two distinct modeling approaches exist for prediction of groundwater flow paths and travel times from the repository location to the designated accessible environment boundary. These two approaches are: (1) the deterministic approach which calculates a single value prediction of groundwater travel time based on average values for input parameters and (2) the stochastic approach which yields a distribution of possible groundwater travel times as a function of the nature and magnitude of uncertainties in the model inputs. The purposes of this report are to (1) document the theoretical (i.e., mathematical) basis used to calculate groundwater pathlines and travel times in a basalt system, (2) outline limitations and ranges of applicability of the deterministic modeling approach, and (3) explain the motivation for the use of the stochastic modeling approach currently being used to predict groundwater pathlines and travel times for the Hanford Site. Example calculations of groundwater travel times are presented to highlight and compare the differences between the deterministic and stochastic modeling approaches. 28 refs

  6. 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

  7. 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

  8. Geochemical modelling of grout-groundwater-rock interactions at the seal-rock interface

    International Nuclear Information System (INIS)

    Alcorn, S.; Christian-Frear, T.

    1992-02-01

    Theoretical investigations into the longevity of repository seals have dealt primarily with the development of a methodology to evaluate interactions between portland cement-based grout and groundwater. Evaluation of chemical thermodynamic equilibria among grout, groundwater, and granitic host rock phases using the geochemical codes EQ3NR/EQ6 suggests that a fracture filled with grout and saturated with groundwater will tend to fill and 'tighten' with time. These calculations predict that some grout and rock phases will dissolve, and that there will be precipitation of secondary phases which collectively have a larger overall volume than that of the material dissolved. Model assumptions include sealing of the fracture in a sluggish hydrologic regime (low gradient) characterized by a saline groundwater environment. The results of the calculations suggest that buffering of the fracture seals chemical system by the granitic rock may be important in determining the long-term fate of grout seals and the resulting phase assemblage in the fracture. The similarity of the predicted reaction product phases to those observed in naturally filled fractures suggests that with time equilibrium will be approached and grouted fractures subject to low hydrologic gradients will continue to seal. If grout injected into fractures materially reduces groundwater flux, the approach to chemical equilibrium will likely be accelerated. In light of this, even very thin or imperfectly grouted fractures would tighten in suitable hydrogeologic environments. In order to determine the period of time necessary to approach equilibrium, data on reaction rates are required. (au)

  9. Sources of groundwater contamination

    International Nuclear Information System (INIS)

    Assaf, H.; Al-Masri, M. S.

    2007-09-01

    In spite of the importance of water for life, either for drinking, irrigation, industry or other wide uses in many fields, human beings seem to contaminate it and make it unsuitable for human uses. This is due to disposal of wastes in the environment without treatment. In addition to population increase and building expanding higher living costs, industrial and economical in growth that causes an increase in water consumption. All of these factors have made an increase pressure on our water environment quantitatively and qualitatively. In addition, there is an increase of potential risks to the water environmental due to disposal of domestic and industrial wastewater in areas near the water sources. Moreover, the use of unacceptable irrigation systems may increase soil salinity and evaporation rates. The present report discusses the some groundwater sources and problem, hot and mineral waters that become very important in our life and to our health due to its chemical and radioactivity characteristics.(authors)

  10. 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.

  11. Groundwater pollution: Are we monitoring appropriate parameters ...

    African Journals Online (AJOL)

    Groundwater pollution is a worldwide phenomenon with potentially disastrous consequences. Prevention of pollution is the ideal approach. However, in practice groundwater quality monitoring is the main tool for timely detection of pollutants and protection of groundwater resources. Monitoring groundwater quality is a ...

  12. A theory of gradient analysis

    NARCIS (Netherlands)

    Braak, ter C.J.F.

    1988-01-01

    The theory of gradient analysis is presented in this chapter, in which the heuristic techniques are integrated with regression, calibration, ordination and constrained ordination as distinct, well-defined statistical problems. The various techniques used for each type of problem are classified into

  13. Compositional gradients in Gramineae genes

    DEFF Research Database (Denmark)

    Wong, Gane Ka-Shu; Wang, Jun; Tao, Lin

    2002-01-01

    In this study, we describe a property of Gramineae genes, and perhaps all monocot genes, that is not observed in eudicot genes. Along the direction of transcription, beginning at the junction of the 5'-UTR and the coding region, there are gradients in GC content, codon usage, and amino-acid usage...

  14. Orderings for conjugate gradient preconditionings

    Science.gov (United States)

    Ortega, James M.

    1991-01-01

    The effect of orderings on the rate of convergence of the conjugate gradient method with SSOR or incomplete Cholesky preconditioning is examined. Some results also are presented that help to explain why red/black ordering gives an inferior rate of convergence.

  15. Color gradients in elliptical galaxies

    International Nuclear Information System (INIS)

    Franx, M.; Illingworth, G.

    1990-01-01

    The relationship of the color gradients within ellipticals and the color differences between them are studied. It is found that the local color appears to be strongly related to the escape velocity. This suggests that the local escape velocity is the primary factor that determines the metallicity of the stellar population. Models with and without dark halos give comparable results. 27 refs

  16. Groundwater sustainability in Central Australia studied using chlorine-36

    International Nuclear Information System (INIS)

    Cresswell, R.G.; Fifield, L.K.; Jacobson, G.

    1998-01-01

    The sustainability of Aboriginal community water supplies in arid Central Australia has been evaluated using the radioisotope chlorine-36 as a tracer within groundwaters to indicate the age of waters being tapped by local bores. Shallow regional groundwaters from fractured sandstones of the Ngalia Basin, fractured metamorphic rocks and Cainozoic sands and gravels show a bimodal distribution of 36 Cl ratios. The higher ratio probably represents modern (Holocene) recharge diluted with windblown salts from local playa lakes and is seen in bores around the margin. The lower ratio corresponds to a 36 Cl age of 80-100ka, implying that the last major recharge occurred during the last interglacial. These values are mainly observed in the interior of the basin, and are believed to be minimum ages for most of the shallow groundwaters in this region. Substantial recharge only appears to occur during favourable interglacial climatic regimes. Most community water supplies depend on these waters. (authors)

  17. Obtaining Samples Representative of Contaminant Distribution in an Aquifer

    International Nuclear Information System (INIS)

    Schalla, Ronald; Spane, Frank A.; Narbutovskih, Susan M.; Conley, Scott F.; Webber, William D.

    2002-01-01

    Historically, groundwater samples collected from monitoring wells have been assumed to provide average indications of contaminant concentrations within the aquifer over the well-screen interval. In-well flow circulation, heterogeneity in the surrounding aquifer, and the sampling method utilized, however, can significantly impact the representativeness of samples as contaminant indicators of actual conditions within the surrounding aquifer. This paper identifies the need and approaches essential for providing cost-effective and technically meaningful groundwater-monitoring results. Proper design of the well screen interval is critical. An accurate understanding of ambient (non-pumping) flow conditions within the monitoring well is essential for determining the contaminant distribution within the aquifer. The ambient in-well flow velocity, flow direction and volumetric flux rate are key to this understanding. Not only do the ambient flow conditions need to be identified for preferential flow zones, but also the probable changes that will be imposed under dynamic conditions that occur during groundwater sampling. Once the in-well flow conditions are understood, effective sampling can be conducted to obtain representative samples for specific depth zones or zones of interest. The question of sample representativeness has become an important issue as waste minimization techniques such as low flow purging and sampling are implemented to combat the increasing cost of well purging and sampling at many hazardous waste sites. Several technical approaches (e.g., well tracer techniques and flowmeter surveys) can be used to determine in-well flow conditions, and these are discussed with respect to both their usefulness and limitations. Proper fluid extraction methods using minimal, (low) volume and no purge sampling methods that are used to obtain representative samples of aquifer conditions are presented

  18. Actinide colloid generation in groundwater

    International Nuclear Information System (INIS)

    Kim, J.I.

    1990-05-01

    The progress made in the investigation of actinide colloid generation in groundwaters is summarized and discussed with particular examples relevant to an understanding of the migration behaviour of actinides in natural aquifer systems. The first part deals with the characterization of colloids: groundwater colloids, actinide real-colloids and actinide pseudocolloids. The second part concentrates on the generation processes and migration behaviour of actinide pseudocolloids, which are discussed with some notable experimental examples. Importance is stressed more on the chemical aspects of the actinide colloid generation in groundwater. This work is a contribution to the CEC project MIRAGE II, particularly, to research area: complexation and colloids. (orig.)

  19. Modeling chemical gradients in sediments under losing and gaining flow conditions: The GRADIENT code

    Science.gov (United States)

    Boano, Fulvio; De Falco, Natalie; Arnon, Shai

    2018-02-01

    Interfaces between sediments and water bodies often represent biochemical hotspots for nutrient reactions and are characterized by steep concentration gradients of different reactive solutes. Vertical profiles of these concentrations are routinely collected to obtain information on nutrient dynamics, and simple codes have been developed to analyze these profiles and determine the magnitude and distribution of reaction rates within sediments. However, existing publicly available codes do not consider the potential contribution of water flow in the sediments to nutrient transport, and their applications to field sites with significant water-borne nutrient fluxes may lead to large errors in the estimated reaction rates. To fill this gap, the present work presents GRADIENT, a novel algorithm to evaluate distributions of reaction rates from observed concentration profiles. GRADIENT is a Matlab code that extends a previously published framework to include the role of nutrient advection, and provides robust estimates of reaction rates in sediments with significant water flow. This work discusses the theoretical basis of the method and shows its performance by comparing the results to a series of synthetic data and to laboratory experiments. The results clearly show that in systems with losing or gaining fluxes, the inclusion of such fluxes is critical for estimating local and overall reaction rates in sediments.

  20. Microbial Functional Gene Diversity Predicts Groundwater Contamination and Ecosystem Functioning.

    Science.gov (United States)

    He, Zhili; Zhang, Ping; Wu, Linwei; Rocha, Andrea M; Tu, Qichao; Shi, Zhou; Wu, Bo; Qin, Yujia; Wang, Jianjun; Yan, Qingyun; Curtis, Daniel; Ning, Daliang; Van Nostrand, Joy D; Wu, Liyou; Yang, Yunfeng; Elias, Dwayne A; Watson, David B; Adams, Michael W W; Fields, Matthew W; Alm, Eric J; Hazen, Terry C; Adams, Paul D; Arkin, Adam P; Zhou, Jizhong

    2018-02-20

    Contamination from anthropogenic activities has significantly impacted Earth's biosphere. However, knowledge about how environmental contamination affects the biodiversity of groundwater microbiomes and ecosystem functioning remains very limited. Here, we used a comprehensive functional gene array to analyze groundwater microbiomes from 69 wells at the Oak Ridge Field Research Center (Oak Ridge, TN), representing a wide pH range and uranium, nitrate, and other contaminants. We hypothesized that the functional diversity of groundwater microbiomes would decrease as environmental contamination (e.g., uranium or nitrate) increased or at low or high pH, while some specific populations capable of utilizing or resistant to those contaminants would increase, and thus, such key microbial functional genes and/or populations could be used to predict groundwater contamination and ecosystem functioning. Our results indicated that functional richness/diversity decreased as uranium (but not nitrate) increased in groundwater. In addition, about 5.9% of specific key functional populations targeted by a comprehensive functional gene array (GeoChip 5) increased significantly ( P contamination and ecosystem functioning. This study indicates great potential for using microbial functional genes to predict environmental contamination and ecosystem functioning. IMPORTANCE Disentangling the relationships between biodiversity and ecosystem functioning is an important but poorly understood topic in ecology. Predicting ecosystem functioning on the basis of biodiversity is even more difficult, particularly with microbial biomarkers. As an exploratory effort, this study used key microbial functional genes as biomarkers to provide predictive understanding of environmental contamination and ecosystem functioning. The results indicated that the overall functional gene richness/diversity decreased as uranium increased in groundwater, while specific key microbial guilds increased significantly as

  1. Investigation of Submarine Groundwater Discharge along the Tidal Reach of the Caloosahatchee River, Southwest Florida

    Science.gov (United States)

    Reich, Christopher D.

    2010-01-01

    marine water or various mixed ratios of fresh and marine water (Martin and others, 2007). In coastal areas where water-table elevations (hydraulic gradients) are steep, such as in Hood Canal, Washington (Swarzenski and others, 2007; Simonds and others, 2008), groundwater entering the coastal marine waters can be fresh (~1-4 parts per thousand, ppt). SGD in coastal locations that have low relief (low hydraulic gradients) such as the study area or other locations in Florida are typically driven by tidal pumping (Reich and others, 2002; 2008; Swarzenski and others, 2008), and water advecting into surface water is composed of recirculated marine water mixed with either fresh or brackish groundwaters. The importance of SGD in the delivery of nutrients and trace elements to coastal environments has been shown to be both beneficial and deleterious to ecosystem health (Valiela and others, 1990). The logical step in studying SGD is to map areas where SGD occurs. Methods such as continuous surface-water radon-222 (222Rn) mapping and electrical resistivity (continuous resistivity profiles, CRP) have been developed and used to identify potential SGD sites (Dulaiova and others, 2005; Swarzenski and others 2004; 2006; 2007; 2008; Reich and others, 2008). CRP data record subsurface, bulk-resistivity measurements to depths up to 25 meters (m). The bulk resistivity can be representative of changes in porewater salinity or in lithology (Reich and others, 2008; Swarzenski and others, 2008). Radon-222 (half-life = 3.28 days) is a natural tracer of groundwater, because sediments and rocks, containing uranium-bearing materials such as limestone and phosphatic material, continually produce 222Rn. Rn-222 (also referred to simply as radon) is an ideal tracer, because there is a constant source. Since radon is a gas, 222Rn does not build up in the surface water but rather evades directly to the atmosphere (Burnett and Dulaiova, 2003; Burnett and others, 2003; Dulaiova and Burnett, 2006).

  2. Tidal pumping as a driver of groundwater discharge to a back barrier salt marsh ecosystem

    Science.gov (United States)

    Carter, M. L.; Viso, R. F.; Peterson, R. N.; Hill, J. C.

    2013-12-01

    Submarine groundwater discharge (SGD) typically consists of both terrestrial groundwater and recirculated seawater and has been shown to be a significant pathway of dissolved substances to the coastal zone. The fresh and saline water mixture in the subsurface creates a salinity gradient that can impact biogeochemical processes. Located along the South Atlantic Bight, Georgia's coastline is an approximately 100-mile stretch of complex primary and secondary barrier islands resulting from geologic interactions driven by long-term sea level rise and retreat, accretion, seasonal tidal events, storm overwash, and wave driven erosion. Our study site is located in the Duplin River near Sapelo Island, GA and is part of the Georgia Coastal Ecosystems Long Term Ecosystem Research (GCE-LTER) program. This area is considered mesotidal (2-4m) and tidal pumping may be a dominating process in controlling SGD rates. The Duplin River is connected to the Atlantic Ocean through Doboy Sound to the south. To the north, the river terminates in extensive salt marsh and therefore has no overland freshwater input. Previous studies show a salinity gradient within the Duplin River indicating that SGD must be present as a source of brackish water. To place constraints on SGD processes, we employ a combination of geochemical and geophysical techniques to determine the magnitude of SGD in the Duplin River. Together these techniques permit a more complete understanding of the groundwater system. Three time series stations at the upper, mid and lower reaches of the Duplin River were deployed in June of 2013 to measure groundwater influences during daily and fortnightly tidal cycles. At each station, continuous radon-222 measurements were conducted at 30 minute intervals along with measurements of water level, temperature and conductivity using standard hydrological data loggers. During this period, eight time series resistivity profiles using a 56 electrode (110m long) cable were recorded to

  3. Microbial Functional Gene Diversity Predicts Groundwater Contamination and Ecosystem Functioning

    Science.gov (United States)

    Zhang, Ping; Wu, Linwei; Rocha, Andrea M.; Shi, Zhou; Wu, Bo; Qin, Yujia; Wang, Jianjun; Yan, Qingyun; Curtis, Daniel; Ning, Daliang; Van Nostrand, Joy D.; Wu, Liyou; Watson, David B.; Adams, Michael W. W.; Alm, Eric J.; Adams, Paul D.; Arkin, Adam P.

    2018-01-01

    ABSTRACT Contamination from anthropogenic activities has significantly impacted Earth’s biosphere. However, knowledge about how environmental contamination affects the biodiversity of groundwater microbiomes and ecosystem functioning remains very limited. Here, we used a comprehensive functional gene array to analyze groundwater microbiomes from 69 wells at the Oak Ridge Field Research Center (Oak Ridge, TN), representing a wide pH range and uranium, nitrate, and other contaminants. We hypothesized that the functional diversity of groundwater microbiomes would decrease as environmental contamination (e.g., uranium or nitrate) increased or at low or high pH, while some specific populations capable of utilizing or resistant to those contaminants would increase, and thus, such key microbial functional genes and/or populations could be used to predict groundwater contamination and ecosystem functioning. Our results indicated that functional richness/diversity decreased as uranium (but not nitrate) increased in groundwater. In addition, about 5.9% of specific key functional populations targeted by a comprehensive functional gene array (GeoChip 5) increased significantly (P contamination and ecosystem functioning. This study indicates great potential for using microbial functional genes to predict environmental contamination and ecosystem functioning. PMID:29463661

  4. Microbial Functional Gene Diversity Predicts Groundwater Contamination and Ecosystem Functioning

    Directory of Open Access Journals (Sweden)

    Zhili He

    2018-02-01

    Full Text Available Contamination from anthropogenic activities has significantly impacted Earth’s biosphere. However, knowledge about how environmental contamination affects the biodiversity of groundwater microbiomes and ecosystem functioning remains very limited. Here, we used a comprehensive functional gene array to analyze groundwater microbiomes from 69 wells at the Oak Ridge Field Research Center (Oak Ridge, TN, representing a wide pH range and uranium, nitrate, and other contaminants. We hypothesized that the functional diversity of groundwater microbiomes would decrease as environmental contamination (e.g., uranium or nitrate increased or at low or high pH, while some specific populations capable of utilizing or resistant to those contaminants would increase, and thus, such key microbial functional genes and/or populations could be used to predict groundwater contamination and ecosystem functioning. Our results indicated that functional richness/diversity decreased as uranium (but not nitrate increased in groundwater. In addition, about 5.9% of specific key functional populations targeted by a comprehensive functional gene array (GeoChip 5 increased significantly (P < 0.05 as uranium or nitrate increased, and their changes could be used to successfully predict uranium and nitrate contamination and ecosystem functioning. This study indicates great potential for using microbial functional genes to predict environmental contamination and ecosystem functioning.

  5. Application of ozone micro-nano-bubbles to groundwater remediation.

    Science.gov (United States)

    Hu, Liming; Xia, Zhiran

    2018-01-15

    Ozone is widely used for water treatment because of its strong oxidation ability. However, the efficiency of ozone in groundwater remediation is limited because of its relatively low solubility and rapid decomposition in the aqueous phase. Methods for increasing the stability of ozone within the subsurface are drawing increasing attention. Micro-nano-bubbles (MNBs), with diameters ranging from tens of nanometres to tens of micrometres, present rapid mass transfer rates, persist for a relatively long time in water, and transport with groundwater flow, which significantly improve gas concentration and provide a continuous gas supply. Therefore, MNBs show a considerable potential for application in groundwater remediation. In this study, the characteristics of ozone MNBs were examined, including their size distribution, bubble quantity, and zeta potential. The mass transfer rate of ozone MNBs was experimentally investigated. Ozone MNBs were then used to treat organics-contaminated water, and they showed remarkable cleanup efficiency. Column tests were also conducted to study the efficiency of ozone MNBs for organics-contaminated groundwater remediation. Based on the laboratory tests, field monitoring was conducted on a trichloroethylene (TCE)-contaminated site. The results showed that ozone MNBs can greatly improve remediation efficiency and represent an innovative technology for in situ remediation of organics-contaminated groundwater. Copyright © 2017 The Author(s). Published by Elsevier B.V. All rights reserved.

  6. Elemental gradients in macrophytes from a reactor effluent gradient

    International Nuclear Information System (INIS)

    Grace, J.B.; Tilly, L.J.

    1978-01-01

    The tissues of submersed macrophtes from along the thermal gradient were analyzed for phosphorus to determine whether any pattern correspondent to standing crop distributions could be detected. Although water concentrations of phosphorus showed no detectable relationship to the thermal effluent, tissue concentrations of this element in submersed macrophytes declined with distance from the effluent entry point. The occurrence of this concentration pattern suggests that phosphorus availability is greater near the discharge. Because phosphorus is the element most often determined to limit aquatic productivity, its greater availability may partially account for the apparent enhancement of macrophte growth near the thermal discharge. A patter of macrophyte abundance which indicated enchancement related to the discharge gradient in the reactor-cooling reservoir, Par Pond is reported. Correlative data tended to implicate light and temperature as important in influencing the differential abundance pattern

  7. Evaporative concentration of arsenic in groundwater: health and environmental implications, La Laguna Region, Mexico.

    Science.gov (United States)

    Ortega-Guerrero, Adrián

    2017-10-01

    High arsenic concentrations in groundwater have been documented in La Laguna Region (LLR) in arid northern Mexico, where arsenic poisoning is both chronic and endemic. A heated debate has continued for decades on its origin. LLR consisted of a series of ancient connected lakes that developed at the end of a topographic depression under closed basin conditions. This study addresses the isotopic, chemical composition of the groundwater and geochemical modeling in the southeasternmost part of the LLR to determine the origin of arsenic. Groundwater samples were obtained from a carbonate and granular aquifers and from a clayey aquitard at terminal Viesca Lake. Results show that groundwater originated as meteoric water that reached the lakes mainly via abundant springs in the carbonate aquifer and perennial flooding of the Nazas-Aguanaval Rivers. Paleo-lake water underwent progressive evaporation as demonstrated by the enrichment of δ 18 O, δ 2 H and characteristic geochemical patterns in the granular aquifer and aquitard that resulted in highly saline (>90,000 mS/cm), arsenic-rich (up to 5000 μg/L) paleo-groundwater (>30,000 years BP). However, adsorption or co-precipitation on iron oxides, clay-mineral surfaces and organic carbon limited arsenic concentration in the groundwater. Arsenic-rich groundwater and other solutes are advancing progressively from the lacustrine margins toward the main granular aquifer, due to reversal of hydraulic gradients caused by intensive groundwater exploitation and the reduction in freshwater runoff provoked by dam construction on the main rivers. Desorption of arsenic will incorporate additional concentrations of arsenic into the groundwater and continue to have significant negative effects on human health and the environment.

  8. Prediction of Groundwater Quality Trends Resulting from Anthropogenic Changes in Southeast Florida.

    Science.gov (United States)

    Yi, Quanghee; Stewart, Mark

    2018-01-01

    The effects of surface water flow system changes caused by constructing water-conservation areas and canals in southeast Florida on groundwater quality under the Atlantic Coastal Ridge was investigated with numerical modeling. Water quality data were used to delineate a zone of groundwater with low total dissolved solids (TDS) within the Biscayne aquifer under the ridge. The delineated zone has the following characteristics. Its location generally coincides with an area where the Biscayne aquifer has high transmissivities, corresponds to a high recharge area of the ridge, and underlies a part of the groundwater mound formed under the ridge prior to completion of the canals. This low TDS groundwater appears to be the result of pre-development conditions rather than seepage from the canals constructed after the 1950s. Numerical simulation results indicate that the time for low TDS groundwater under the ridge to reach equilibrium with high TDS surface water in the water-conservation areas and Everglades National Park are approximately 70 and 60 years, respectively. The high TDS groundwater would be restricted to the water-conservation areas and the park due to its slow eastward movement caused by small hydraulic gradients in Rocky Glades and its mixing with the low TDS groundwater under the high-recharge area of the ridge. The flow or physical boundary conditions such as high recharge rates or low hydraulic conductivity layers may affect how the spatial distribution of groundwater quality in an aquifer will change when a groundwater flow system reaches equilibrium with an associated surface water flow system. © 2017, National Ground Water Association.

  9. Current Status of Groundwater Monitoring Networks in Korea

    OpenAIRE

    Jin-Yong Lee; Kideok D. Kwon

    2016-01-01

    Korea has been operating groundwater monitoring systems since 1996 as the Groundwater Act enacted in 1994 enforces nationwide monitoring. Currently, there are six main groundwater monitoring networks operated by different government ministries with different purposes: National Groundwater Monitoring Network (NGMN), Groundwater Quality Monitoring Network (GQMN), Seawater Intrusion Monitoring Network (SIMN), Rural Groundwater Monitoring Network (RGMN), Subsidiary Groundwater Monitoring Network ...

  10. Human impact gradient on mammalian biodiversity

    Directory of Open Access Journals (Sweden)

    Mariana Munguía

    2016-04-01

    Full Text Available Drastic changes have been caused by human influence in natural landscapes, which may exert an intensive effect on species loss. However, species loss from human pressure is not random but depends on a series of environmentally associated factors. Linking species traits to environmental attributes may allow us to detect the ecological impacts of habitat so that meaningful habitat degradation gradients can be identified. The relationships between environmental factors and species traits provide the basis for identifying those biological traits that make species more sensitive to disturbance. These relationships are also helpful to detect the geographic distribution of latent risk to reveal areas where biodiversity is threatened. Here, we identify a “Human Impact Gradient for Biodiversity (HIGB” based on a three-table ordination method (RLQ analysis and fourth-corner analysis to identify key species traits that are associated with environmental gradient. Species distribution and environmental geographic data were gathered nationwide to analyze 68 localities, which represent 27% of Mexico’s surface, including 211 species of mammals. Nine environmental variables (including biophysical, geophysical and land-use impacts were analyzed by using the Geographic Information System. Three types of species’ traits were evaluated: locomotion, trophic habit and body size. We identified a human impact gradient, which was mainly determined by the percentage of the area that was covered by seedlings, the plant richness, the understory coverage percentage and the human settlement index. The most important species traits that are associated with non-human-impacted sites were carnivores, frugivores–herbivores and a body size that was greater than 17.8 kg; 25 species were selected by the decision criteria framework for species that were sensitive to degradation based on ecological function information. Conversely, granivores, fossorial and semifossorial

  11. Migration of inclusions in solids in stress gradients

    International Nuclear Information System (INIS)

    Olander, D.R.

    1980-01-01

    A theoretical method of assessing the influence of stress and temperature gradients on the motion of inclusions in solids is developed. In nonuniform stress fields, the stress distribution on the surface of the cavity must be calculated and transformed to a potential gradient for driving a surface atom flux. The bubble migration velocity is the first Legendre coefficient of the surface flux. Higher order components represent distortion. The stress gradient effect appears only in small-magnitude terms in the surface chemical potential, specifically in the stress effect on the solid atomic volume and in the elastic energy density. The migration velocities of spherical and faceted bubbles in solids are computed and the extent of distortion of a spherical bubble is estimated. The role of vacancy exchange with the bulk solid on the migration velocity is assessed. (author)

  12. Decadal variations in groundwater quality

    DEFF Research Database (Denmark)

    Jessen, Søren; Postma, Dieke; Thorling, Lærke

    2017-01-01

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

  13. Groundwater-dependent ecosystems: recent insights from satellite and field-based studies

    Science.gov (United States)

    Eamus, D.; Zolfaghar, S.; Villalobos-Vega, R.; Cleverly, J.; Huete, A.

    2015-10-01

    review of two case studies of the impacts of GW extraction and then provide an ecosystem-scale, multiple trait, integrated metric of the impact of differences in groundwater depth on the structure and function of eucalypt forests growing along a natural gradient in depth-to-groundwater. We conclude with a discussion of a depth-to-groundwater threshold in this mesic GDE. Beyond this threshold, significant changes occur in ecosystem structure and function.

  14. Speciation, Mobility and Fate of Actinides in the Groundwater at the Hanford Site

    International Nuclear Information System (INIS)

    Buesseler, K.O.; Dai, M.; Repeta, D.; Wacker, J.F.; Kelley, J.M.

    2003-01-01

    Plutonium and other actinides represent important contaminants in the groundwater and vadose zone at Hanford and other DOE sites. The distribution and migration of these actinides in groundwater must be understood so that these sites can be carefully monitored and effectively cleaned up, thereby minimizing risks to the public. The objective of this project was to obtain field data on the chemical and physical forms of plutonium in groundwater at the Hanford site. We focused on the 100-k and 100-n areas near the Columbia River, where prior reactor operations and waste storage was in close proximity to the river. In particular, a unique set of technical approaches were combined to look at the details of Pu speciation in groundwater, as thus its chemical affinity for soil surfaces and solubility in groundwater, as these impact directly the migration rates off site and possible mitigation possibilities one might undertake to control, or at least better monitor these releases

  15. Gradients of microhabitat and crappie (Pomoxis spp.) distributions in reservoir coves

    Science.gov (United States)

    Kaczka, Levi J.; Miranda, Leandro E.

    2013-01-01

    Embayments are among the most widespread littoral habitats found in Mississippi flood-control reservoirs. These macrohabitats represent commonly used nursery zones for age-0 crappies, Pomoxis spp., despite barren and eroded shorelines formed over 60–70 years of annual water level fluctuations. We tested if embayments displayed microhabitat gradients linked to the effect of water level fluctuations on riparian vegetation and if these gradients were paralleled by gradients in age-0 crappie distribution. Habitat composition changed longitudinally along the embayments with the most pronounced gradient representing a shift from nonvegetated mudflats near the mouth of embayments to herbaceous material upstream. The degree of habitat change depended on the water level. Similarly, catch rates of crappies increased upstream toward the rear of embayments, differing among water levels and reservoirs, but the longitudinal pattern persisted. Our results indicate that habitat composition gradients occur in embayments of northwest Mississippi flood-control reservoirs and that these gradients may influence a similar gradient in age-0 crappie distribution. While the biotic interactions behind the gradients may be less clear, we speculate that water level is the main factor influencing the observed gradients in habitat composition and fish. Management to benefit age-0 crappies may involve habitat improvement along embayment shorelines and water level regimes that foster growth of herbaceous plants.

  16. Assessment of emerging groundwater contaminants

    OpenAIRE

    Stuart, Marianne; Lapworth, Dan; Manamsa, Katya; Crane, Emily; White, Debbie

    2016-01-01

    Emerging contaminants in groundwater are important. These have been studied at a range of scales. An increasing range of compounds is being detected Urban areas show impact of sewage and industrial wastewater. Some ECs are probably no threat to drinking water at such µg/L concentrations, e.g. caffeine Others may prove to be in the future. There is little information on their impact on other groundwater receptors in the environment. We are still far from understanding which of these comp...

  17. Groundwater sampling in uranium reconnaissance

    International Nuclear Information System (INIS)

    Butz, T.R.

    1977-03-01

    The groundwater sampling program is based on the premise that ground water geochemistry reflects the chemical composition of, and geochemical processes active in the strata from which the sample is obtained. Pilot surveys have shown that wells are the best source of groundwater, although springs are sampled on occasion. The procedures followed in selecting a sampling site, the sampling itself, and the field measurements, as well as the site records made, are described

  18. Assessment of ground-water contamination from a leaking underground storage tank at a defense supply center near Richmond, Virginia

    International Nuclear Information System (INIS)

    Powell, J.D.; Wright, W.G.

    1990-01-01

    During 1988-89, 24 wells were installed in the vicinity of the post-exchange gasoline station on the Defense General Supply Center, near Richmond, Virginia, to collect and analyze groundwater samples for the presence of gasoline contamination from a leaking underground storage tank. Concentrations of total petroleum hydrocarbons and benzene were as high as 8.2 mg/L and 9,000 microg/L, respectively, in water from wells in the immediate vicinity of the former leaking tank, and benzene concentrations were as high as 2,300 microg/L in a well 600 ft down gradient from the gasoline station. Groundwater flow rate are estimated to be about 60 to 80 ft/yr; on the basis of these flow rates, the contaminants may have been introduced into the groundwater as long as 7-10 yrs ago. Groundwater might infiltrate a subsurface storm sewer, where the sewer is below the water table, and discharge into a nearby stream. Preliminary risk assessment for the site identified no potential human receptors to the groundwater contamination because there were no groundwater users identified in the area. Remediation might be appropriate if exposure of future potential users is concern. Alternatives discussed for remediation of groundwater contamination in the upper aquifer at the PX Service Station include no-action, soil vapor extraction, and groundwater pumping and treatment alternatives

  19. Hoe Creek groundwater restoration, 1989

    Energy Technology Data Exchange (ETDEWEB)

    Renk, R.R.; Crader, S.E.; Lindblom, S.R.; Covell, J.R.

    1990-01-01

    During the summer of 1989, approximately 6.5 million gallons of contaminated groundwater were pumped from 23 wells at the Hoe Creek underground coal gasification site, near Gillette, Wyoming. The organic contaminants were removed using activated carbon before the water was sprayed on 15.4 acres at the sites. Approximately 2647 g (5.8 lb) of phenols and 10,714 g (23.6 lb) of benzene were removed from the site aquifers. Phenols, benzene, toluene, ethylbenzene, and naphthalene concentrations were measured in 43 wells. Benzene is the only contaminant at the site exceeds the federal standard for drinking water (5 {mu}g/L). Benzene leaches into the groundwater and is slow to biologically degrade; therefore, the benzene concentration has remained high in the groundwater at the site. The pumping operation affected groundwater elevations across the entire 80-acre site. The water levels rebounded quickly when the pumping operation was stopped on October 1, 1989. Removing contaminated groundwater by pumping is not an effective way to clean up the site because the continuous release of benzene from coal tars is slow. Benzene will continue to leach of the tars for a long time unless its source is removed or the leaching rate retarded through mitigation techniques. The application of the treated groundwater to the surface stimulated plant growth. No adverse effects were noted or recorded from some 60 soil samples taken from twenty locations in the spray field area. 20 refs., 52 figs., 8 tabs.

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

    Science.gov (United States)

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

    2018-02-01

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

  1. 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.

  2. Pre/post-closure assessment of groundwater pharmaceutical fate in a wastewater‑facility-impacted stream reach

    Science.gov (United States)

    Bradley, Paul M.; Barber, Larry B.; Clark, Jimmy M.; Duris, Joseph W.; Foreman, William T.; Furlong, Edward T.; Givens, Carrie E.; Hubbard, Laura E.; Hutchinson, Kasey J.; Journey, Celeste A.; Keefe, Steffanie H.; Kolpin, Dana W.

    2016-01-01

    Pharmaceutical contamination of contiguous groundwater is a substantial concern in wastewater-impacted streams, due to ubiquity in effluent, high aqueous mobility, designed bioactivity, and to effluent-driven hydraulic gradients. Wastewater treatment facility (WWTF) closures are rare environmental remediation events; offering unique insights into contaminant persistence, long-term wastewater impacts, and ecosystem recovery processes. The USGS conducted a combined pre/post-closure groundwater assessment adjacent to an effluent-impacted reach of Fourmile Creek, Ankeny, Iowa, USA. Higher surface-water concentrations, consistent surface-water to groundwater concentration gradients, and sustained groundwater detections tens of meters from the stream bank demonstrated the importance of WWTF effluent as the source of groundwater pharmaceuticals as well as the persistence of these contaminants under effluent-driven, pre-closure conditions. The number of analytes (110 total) detected in surface water decreased from 69 prior to closure down to 8 in the first post-closure sampling event approximately 30 d later, with a corresponding 2 order of magnitude decrease in the cumulative concentration of detected analytes. Post-closure cumulative concentrations of detected analytes were approximately 5 times higher in proximal groundwater than in surface water. About 40% of the 21 contaminants detected in a downstream groundwater transect immediately before WWTF closure exhibited rapid attenuation with estimated half-lives on the order of a few days; however, a comparable number exhibited no consistent attenuation during the year-long post-closure assessment. The results demonstrate the potential for effluent-impacted shallow groundwater systems to accumulate pharmaceutical contaminants and serve as long-term residual sources, further increasing the risk of adverse ecological effects in groundwater and the near-stream ecosystem.

  3. Ground-water flow and water quality in the Upper Floridan aquifer, southwestern Albany area, Georgia, 1998-2001

    Science.gov (United States)

    Warner, Debbie; Lawrence, Stephen J.

    2005-01-01

    During 1997, the Dougherty County Health Department sampled more than 700 wells completed in the Upper Floridan aquifer in Dougherty County, Georgia, and determined that nitrate as nitrogen (hereinafter called nitrate) concentrations were above 10 milligrams per liter (mg/L) in 12 percent of the wells. Ten mg/L is the Georgia primary drinking-water standard. The ground-water flow system is complex and poorly understood in this predominantly agricultural area. Therefore, the U.S. Geological Survey (USGS) - in cooperation with Albany Water, Gas and Light Commission - conducted a study to better define ground-water flow and water quality in the Upper Florida aquifer in the southwestern Albany area, Georgia. Ground-water levels were measured in the southwestern Albany area, Georgia, during May 1998 and March 1999 (spring), and October 1998 and September 1999 (fall). Groundwater levels measured in 75 wells open only to the Upper Floridan aquifer were used to construct potentiometric-surface maps for those four time periods. These maps show that ground water generally flows from northwest to southeast at gradients ranging from about 2 to greater than 10 feet per mile. During spring and fall 1998, ground-water levels were high and mounding of the potentiometric surface occurred in the central part of the study area, indicating a local recharge area. Water levels declined from December through February, and by March 1999 the mound in the potentiometric surface had dissipated. Of the 75 wells in the potentiometric network, 24 were selected for a water-quality network. These 24 wells and 1 spring were sampled during fall 1998 and spring 1999. Samples were analyzed for major chemical constituents, selected minor constituents, selected nutrients, and chlorofluorocarbons (CFC). Water-quality field measurements - such as water temperature, pH, specific conductance (SC), and dissolved oxygen (DO) - were taken at each well. During August 2000, a ground-water sample was collected

  4. Computational Strain Gradient Crystal Plasticity

    DEFF Research Database (Denmark)

    Niordson, Christian Frithiof; Kysar, Jeffrey W.

    2011-01-01

    A model for strain gradient crystal visco-plasticity is formulated along the lines proposed by Fleck andWillis (2009) for isotropic plasticity. Size-effects are included in the model due to the addition of gradient terms in both the free energy as well as through a dissipation potential. A finite...... element solution method is presented, which delivers the slip-rate field and the velocity-field based on two minimum principles. Some plane deformation problems relevant for certain specific orientations of a face centered cubic crystal under plane loading conditions are studied, and effective in......-plane parameters are developed based on the crystallographic properties of the material. The problem of cyclic shear of a single crystal between rigid platens is studied as well as void growth of a cylindrical void....

  5. Computational strain gradient crystal plasticity

    DEFF Research Database (Denmark)

    Niordson, Christian Frithiof; Kysar, Jeffrey W.

    2014-01-01

    A numerical method for viscous strain gradient crystal plasticity theory is presented, which incorporates both energetic and dissipative gradient effects. The underlying minimum principles are discussed as well as convergence properties of the proposed finite element procedure. Three problems...... of plane crystal plasticity are studied: pure shear of a single crystal between rigid platens as well as plastic deformation around cylindrical voids in hexagonal close packed and face centered cubic crystals. Effective in-plane constitutive slip parameters for plane strain deformation of specifically...... oriented face centered cubic crystals are developed in terms of the crystallographic slip parameters. The effect on geometrically necessary dislocation structures introduced by plastic deformation is investigated as a function of the ratio of void radius to plasticity length scale....

  6. Vertebrate pressure-gradient receivers

    DEFF Research Database (Denmark)

    Christensen-Dalsgaard, Jakob

    2011-01-01

    The eardrums of all terrestrial vertebrates (tetrapods) are connected through Eustachian tubes or interaural canals. In some of the animals, these connections create pressure-gradient directionality, an enhanced directionality by interaction of sound arriving at both sides of the eardrum and stro......The eardrums of all terrestrial vertebrates (tetrapods) are connected through Eustachian tubes or interaural canals. In some of the animals, these connections create pressure-gradient directionality, an enhanced directionality by interaction of sound arriving at both sides of the eardrum....... Recent vertebrates form a continuum from perfect interaural transmission (0 dB in a certain frequency band) and pronounced eardrum directionality (30-40 dB) in the lizards, over somewhat attenuated transmission and limited directionality in birds and frogs, to the strongly attenuated interaural...

  7. A Commune-Level Groundwater Potential Map for the Republic of Mali

    Directory of Open Access Journals (Sweden)

    Silvia Díaz-Alcaide

    2017-10-01

    Full Text Available Groundwater represents an essential resource in sub-Saharan Africa, where several hundred million people rely on aquifers for domestic supply. This paper presents a method to map groundwater potential in the Republic of Mali based on a spatially-distributed database of 26,040 boreholes. The database includes exhaustive information on key parameters such as borehole location, success rate of borehole production, depth, yield, static groundwater level or water quality. Representative variables were classified and interpreted jointly to develop a groundwater potential index for each of the 703 communes in Mali. This provides a methodological novelty because groundwater potential studies typically rely on indirect indicators such as lineaments, slope, soil moisture and landforms. Also, such large borehole databases have seldom been used to estimate groundwater potential. The highest indexes were obtained for the areas in and around the River Niger’s Inner Delta, including southern Tombouctou and the central parts of the Ségou and Mopti Regions. The lower Precambrian formations, which include the country’s thoroughly populated southern plateau, had moderate scores. The lowest groundwater potential was found in the northern part of the Kayes and Koulikoro Regions, as well as in the entire region of Kidal. By providing results at the commune scale, these outcomes show that groundwater potential across the country’s geological and hydrogeological units can be highly variable, and that local and regional-scale information may be useful for groundwater management purposes. These results are policy-relevant in a context of rapid change and population growth, where groundwater resources can be expected to be increasingly relied upon in the coming years.

  8. Source and Processes of Dissolved Organic Matter in a Bangladesh Groundwater

    Science.gov (United States)

    McKnight, D. M.; Simone, B. E.; Mladenov, N.; Zheng, Y.; Legg, T. M.; Nemergut, D.

    2010-12-01

    Arsenic contamination of groundwater is a global health crisis, especially in Bangladesh where an estimated 40 million people are at risk. The release of geogenic arsenic bound to sediments into groundwater is thought to be influenced by dissolved organic matter (DOM) through several biogeochemical processes. Abiotically, DOM can promote the release of sediment bound As through the formation of DOM-As complexes and competitive interactions between As and DOM for sorption sites on the sediment. Additionally, the labile portion of groundwater DOM can serve as an electron donor to support microbial growth and the more recalcitrant humic DOM may serve as an electron shuttle, facilitating the eventual reduction of ferric iron present as iron oxides in sediments and consequently the mobilization of sorbed As and organic material. The goal of this study is to understand the source of DOM in representative Bangladesh groundwaters and the DOM sorption processes that occur at depth. We report chemical characteristics of representative DOM from a surface water, a shallow low-As groundwater, mid-depth high-As groundwater from the Araihazar region of Bangladesh. The humic DOM from groundwater displayed a more terrestrial chemical signature, indicative of being derived from plant and soil precursor materials, while the surface water humic DOM had a more microbial signature, suggesting an anthropogenic influence. In terms of biogeochemical processes occurring in the groundwater system, there is evidence from a diverse set of chemical characteristics, ranging from 13C-NMR spectroscopy to the analysis of lignin phenols, for preferential sorption onto iron oxides influencing the chemistry and reactivity of humic DOM in high As groundwater in Bangladesh. Taken together, these results provide chemical evidence for anthropogenic influence and the importance of sorption reactions at depth controlling the water quality of high As groundwater in Bangladesh.

  9. Mathematical modelling of digit specification by a sonic hedgehog gradient

    KAUST Repository

    Woolley, Thomas E.; Baker, Ruth E.; Tickle, Cheryll; Maini, Philip K.; Towers, Matthew

    2013-01-01

    Background: The three chick wing digits represent a classical example of a pattern specified by a morphogen gradient. Here we have investigated whether a mathematical model of a Shh gradient can describe the specification of the identities of the three chick wing digits and if it can be applied to limbs with more digits. Results: We have produced a mathematical model for specification of chick wing digit identities by a Shh gradient that can be extended to the four digits of the chick leg with Shh-producing cells forming a digit. This model cannot be extended to specify the five digits of the mouse limb. Conclusions: Our data suggest that the parameters of a classical-type morphogen gradient are sufficient to specify the identities of three different digits. However, to specify more digit identities, this core mechanism has to be coupled to alternative processes, one being that in the chick leg and mouse limb, Shh-producing cells give rise to digits; another that in the mouse limb, the cellular response to the Shh gradient adapts over time so that digit specification does not depend simply on Shh concentration. Developmental Dynamics 243:290-298, 2014. © 2013 Wiley Periodicals, Inc.

  10. Spheroidal Integral Equations for Geodetic Inversion of Geopotential Gradients

    Science.gov (United States)

    Novák, Pavel; Šprlák, Michal

    2018-03-01

    The static Earth's gravitational field has traditionally been described in geodesy and geophysics by the gravitational potential (geopotential for short), a scalar function of 3-D position. Although not directly observable, geopotential functionals such as its first- and second-order gradients are routinely measured by ground, airborne and/or satellite sensors. In geodesy, these observables are often used for recovery of the static geopotential at some simple reference surface approximating the actual Earth's surface. A generalized mathematical model is represented by a surface integral equation which originates in solving Dirichlet's boundary-value problem of the potential theory defined for the harmonic geopotential, spheroidal boundary and globally distributed gradient data. The mathematical model can be used for combining various geopotential gradients without necessity of their re-sampling or prior continuation in space. The model extends the apparatus of integral equations which results from solving boundary-value problems of the potential theory to all geopotential gradients observed by current ground, airborne and satellite sensors. Differences between spherical and spheroidal formulations of integral kernel functions of Green's kind are investigated. Estimated differences reach relative values at the level of 3% which demonstrates the significance of spheroidal approximation for flattened bodies such as the Earth. The observation model can be used for combined inversion of currently available geopotential gradients while exploring their spectral and stochastic characteristics. The model would be even more relevant to gravitational field modelling of other bodies in space with more pronounced spheroidal geometry than that of the Earth.

  11. Mathematical modelling of digit specification by a sonic hedgehog gradient

    KAUST Repository

    Woolley, Thomas E.

    2013-11-26

    Background: The three chick wing digits represent a classical example of a pattern specified by a morphogen gradient. Here we have investigated whether a mathematical model of a Shh gradient can describe the specification of the identities of the three chick wing digits and if it can be applied to limbs with more digits. Results: We have produced a mathematical model for specification of chick wing digit identities by a Shh gradient that can be extended to the four digits of the chick leg with Shh-producing cells forming a digit. This model cannot be extended to specify the five digits of the mouse limb. Conclusions: Our data suggest that the parameters of a classical-type morphogen gradient are sufficient to specify the identities of three different digits. However, to specify more digit identities, this core mechanism has to be coupled to alternative processes, one being that in the chick leg and mouse limb, Shh-producing cells give rise to digits; another that in the mouse limb, the cellular response to the Shh gradient adapts over time so that digit specification does not depend simply on Shh concentration. Developmental Dynamics 243:290-298, 2014. © 2013 Wiley Periodicals, Inc.

  12. Conditioning the full-waveform inversion gradient to welcome anisotropy

    KAUST Repository

    Alkhalifah, Tariq Ali

    2015-04-23

    Multiparameter full-waveform inversion (FWI) suffers from complex nonlinearity in the objective function, compounded by the eventual trade-off between the model parameters. A hierarchical approach based on frequency and arrival time data decimation to maneuver the complex nonlinearity associated with this problem usually falls short in anisotropic media. In place of data decimation, I use a model gradient filter approach to access the parts of the gradient more suitable to combat the potential nonlinearity and parameter trade-off. The filter is based on representing the gradient in the time-lag normalized domain, in which small scattering-angles of the gradient update are initially muted out. The model update hierarchical filtering strategy include applying varying degrees of filtering to the different anisotropic parameter updates, a feature not easily accessible to simple data decimation. Using FWI and reflection-based FWI, when the modeled data are obtained with the single-scattering theory, allows access to additional low model wavenumber components. Combining such access to wavenumbers with scattering-angle filters applied to the individual parameter gradients allows for multiple strategies to avoid complex FWI nonlinearity as well as the parameter trade-off.

  13. Primordial vorticity and gradient expansion

    CERN Document Server

    Giovannini, Massimo

    2012-01-01

    The evolution equations of the vorticities of the electrons, ions and photons in a pre-decoupling plasma are derived, in a fully inhomogeneous geometry, by combining the general relativistic gradient expansion and the drift approximation within the Adler-Misner-Deser decomposition. The vorticity transfer between the different species is discussed in this novel framework and a set of general conservation laws, connecting the vorticities of the three-component plasma with the magnetic field intensity, is derived. After demonstrating that a source of large-scale vorticity resides in the spatial gradients of the geometry and of the electromagnetic sources, the total vorticity is estimated to lowest order in the spatial gradients and by enforcing the validity of the momentum constraint. By acknowledging the current bounds on the tensor to scalar ratio in the (minimal) tensor extension of the $\\Lambda$CDM paradigm the maximal comoving magnetic field induced by the total vorticity turns out to be, at most, of the or...

  14. A quantitative assessment of groundwater resources in the Middle East and North Africa region

    Science.gov (United States)

    Lezzaik, Khalil; Milewski, Adam

    2018-02-01

    The Middle East and North Africa (MENA) region is the world's most water-stressed region, with its countries constituting 12 of the 15 most water-stressed countries globally. Because of data paucity, comprehensive regional-scale assessments of groundwater resources in the MENA region have been lacking. The presented study addresses this issue by using a distributed ArcGIS model, parametrized with gridded data sets, to estimate groundwater storage reserves in the region based on generated aquifer saturated thickness and effective porosity estimates. Furthermore, monthly gravimetric datasets (GRACE) and land surface parameters (GLDAS) were used to quantify changes in groundwater storage between 2003 and 2014. Total groundwater reserves in the region were estimated at 1.28 × 106 cubic kilometers (km3) with an uncertainty range between 816,000 and 1.93 × 106 km3. Most of the reserves are located within large sedimentary basins in North Africa and the Arabian Peninsula, with Algeria, Libya, Egypt, and Saudi Arabia accounting for approximately 75% of the region's total freshwater reserves. Alternatively, small groundwater reserves were found in fractured Precambrian basement exposures. As for groundwater changes between 2003 and 2014, all MENA countries except for Morocco exhibited declines in groundwater storage. However, given the region's large groundwater reserves, groundwater changes between 2003 and 2014 are minimal and represent no immediate short-term threat to the MENA region, with some exceptions. Notwithstanding this, the study recommends the development of sustainable and efficient groundwater management policies to optimally utilize the region's groundwater resources, especially in the face of climate change, demographic expansion, and socio-economic development.

  15. Impacts of Continuous Electron Beam Accelerator Facility operations on groundwater and surface water: Appendix 9

    International Nuclear Information System (INIS)

    Lee, D.W.

    1986-04-01

    The operation of the proposed Continuous Electron Beam Accelerator Facility (CEBAF) at Newport News, Virginia, is expected to result in the activation and subsequent contamination of water resources in the vicinity of the accelerator. Since the proposed site is located in the headwaters of the watershed supplying Big Bethel Reservoir, concern has been expressed about possible contamination of water resources used for consumption. Data characterizing the surface water and groundwater regime in the site area are limited. A preliminary geotechnical investigation of the site has been completed (LAW 1985). This investigation concluded that groundwater flow is generally towards the southeast at an estimated velocity of 2.5 m/y. This conclusion is based on groundwater and soil boring data and is very preliminary in nature. This analysis makes use of the data and conclusions developed during the preliminary geotechnical investigation to provide an upper-bound assessment of radioactive contamination from CEBAF operations. A site water balance was prepared to describe the behavior of the hydrologic environment that is in close agreement with the observed data. The transport of contamination in the groundwater regime is assessed using a one-dimensional model. The groundwater model includes the mechanisms of groundwater flow, groundwater recharge, radioactive decay, and groundwater activation. The model formulation results in a closed-form, exact, analytic solution of the concentration of contamination in the groundwater. The groundwater solution is used to provide a source term for a surface-water analysis. The surface-water and groundwater models are prepared for steady state conditions such that they represent conservative evaluations of CEBAF operations

  16. Seasonal and Spatial Variability of Anthropogenic and Natural Factors Influencing Groundwater Quality Based on Source Apportionment

    Directory of Open Access Journals (Sweden)

    Xueru Guo

    2018-02-01

    Full Text Available Globally, groundwater resources are being deteriorated by rapid social development. Thus, there is an urgent need to assess the combined impacts of natural and enhanced anthropogenic sources on groundwater chemistry. The aim of this study was to identify seasonal characteristics and spatial variations in anthropogenic and natural effects, to improve the understanding of major hydrogeochemical processes based on source apportionment. 34 groundwater points located in a riverside groundwater resource area in northeast China were sampled during the wet and dry seasons in 2015. Using principal component analysis and factor analysis, 4 principal components (PCs were extracted from 16 groundwater parameters. Three of the PCs were water-rock interaction (PC1, geogenic Fe and Mn (PC2, and agricultural pollution (PC3. A remarkable difference (PC4 was organic pollution originating from negative anthropogenic effects during the wet season, and geogenic F enrichment during the dry season. Groundwater exploitation resulted in dramatic depression cone with higher hydraulic gradient around the water source area. It not only intensified dissolution of calcite, dolomite, gypsum, Fe, Mn and fluorine minerals, but also induced more surface water recharge for the water source area. The spatial distribution of the PCs also suggested the center of the study area was extremely vulnerable to contamination by Fe, Mn, COD, and F−.

  17. 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.

  18. Bikini Atoll groundwater development

    International Nuclear Information System (INIS)

    Peterson, F.L.

    1985-01-01

    Nuclear weapons testing during the 1950's has left the soil and ground water on Bikini Atoll contaminated with cesium-137, and to a lesser extent, strontium-90. Plans currently are underway for the clean-up and resettlement of the atoll by removal of approximately the upper 30 cm of soil. Any large-scale resettlement program must include provisions for water supply. This will be achieved principally by catchment and storage of rain water, however, since rainfall in Bikini is highly seasonal and droughts occur frequently, ground water development must also be considered. The quantity of potable ground water that can be developed is limited by its salinity and radiological quality. The few ground water samples available from Bikini, which have been collected from only about the top meter of the groundwater body, indicate that small bodies of potable ground water exist on Bikini and Eneu, the two principal living islands, but that cesium and strontium in the Bikioni ground water exceed drinking water standards. In order to make a reasonable estimate of the ground water development potential for the atoll, some 40 test boreholes will be drilled during July/August 1985, and a program of water quality monitoring initiated. This paper will describe preliminary results of the drilling and monitoring work

  19. The Role of Frozen Soil in Groundwater Discharge Predictions for Warming Alpine Watersheds

    Science.gov (United States)

    Evans, Sarah G.; Ge, Shemin; Voss, Clifford I.; Molotch, Noah P.

    2018-03-01

    Climate warming may alter the quantity and timing of groundwater discharge to streams in high alpine watersheds due to changes in the timing of the duration of seasonal freezing in the subsurface and snowmelt recharge. It is imperative to understand the effects of seasonal freezing and recharge on groundwater discharge to streams in warming alpine watersheds as streamflow originating from these watersheds is a critical water resource for downstream users. This study evaluates how climate warming may alter groundwater discharge due to changes in seasonally frozen ground and snowmelt using a 2-D coupled flow and heat transport model with freeze and thaw capabilities for variably saturated media. The model is applied to a representative snowmelt-dominated watershed in the Rocky Mountains of central Colorado, USA, with snowmelt time series reconstructed from a 12 year data set of hydrometeorological records and satellite-derived snow covered area. Model analyses indicate that the duration of seasonal freezing in the subsurface controls groundwater discharge to streams, while snowmelt timing controls groundwater discharge to hillslope faces. Climate warming causes changes to subsurface ice content and duration, rerouting groundwater flow paths but not altering the total magnitude of future groundwater discharge outside of the bounds of hydrologic parameter uncertainties. These findings suggest that frozen soil routines play an important role for predicting the future location of groundwater discharge in watersheds underlain by seasonally frozen ground.

  20. The role of frozen soil in groundwater discharge predictions for warming alpine watersheds

    Science.gov (United States)

    Evans, Sarah G.; Ge, Shemin; Voss, Clifford I.; Molotch, Noah P.

    2018-01-01

    Climate warming may alter the quantity and timing of groundwater discharge to streams in high alpine watersheds due to changes in the timing of the duration of seasonal freezing in the subsurface and snowmelt recharge. It is imperative to understand the effects of seasonal freezing and recharge on groundwater discharge to streams in warming alpine watersheds as streamflow originating from these watersheds is a critical water resource for downstream users. This study evaluates how climate warming may alter groundwater discharge due to changes in seasonally frozen ground and snowmelt using a 2‐D coupled flow and heat transport model with freeze and thaw capabilities for variably saturated media. The model is applied to a representative snowmelt‐dominated watershed in the Rocky Mountains of central Colorado, USA, with snowmelt time series reconstructed from a 12 year data set of hydrometeorological records and satellite‐derived snow covered area. Model analyses indicate that the duration of seasonal freezing in the subsurface controls groundwater discharge to streams, while snowmelt timing controls groundwater discharge to hillslope faces. Climate warming causes changes to subsurface ice content and duration, rerouting groundwater flow paths but not altering the total magnitude of future groundwater discharge outside of the bounds of hydrologic parameter uncertainties. These findings suggest that frozen soil routines play an important role for predicting the future location of groundwater discharge in watersheds underlain by seasonally frozen ground.

  1. Gradient computation for VTI acoustic wavefield tomography

    KAUST Repository

    Li, Vladimir; Wang, Hui; Tsvankin, Ilya; Diaz, Esteban; Alkhalifah, Tariq Ali

    2016-01-01

    -power objective functions. We also obtain the gradient expressions for the data-domain objective function, which can incorporate borehole information necessary for stable VTI velocity analysis. These gradients are compared to the ones obtained with a space

  2. Hydrogeochemical processes influencing groundwater quality within the Lower Pra Basin

    International Nuclear Information System (INIS)

    Tay, Collins

    2015-12-01

    evaporation playing an insignificant role on the infiltrating water. However, with reference to the Local Meteoric Water Line (LMWL) for the Accra Plains by Akiti (1986), the results suggest evidence of isotopic enrichment by evaporation on the surface or in the unsaturated zone before recharge into the groundwater system. Hydrochemical facies delineated two main water types, the Ca-Mg-HCO 3 and Na-HCO 3 water types, with Ca-Mg-Cl and Na-Cl as minor water types. Using Q-mode Hierarchical Cluster Analyses (HCA), surface and groundwater within the basin have been characterized into four (4) water groups and five (5) subgroups. Water quality data for subgroups show that, Groups 1 and 2 waters both represent a transition zone between Ca-Mg-HCO 3 /Na-HCO 3 and Na-Cl/ Ca-Mg-Cl /Na-SO 4 water types and therefore, can be regarded as transition zones between groundwaters which evolved from Ca-Mg-HCO 3 water type into Na-HCO 3 , Ca-Mg-Cl, and Na-Cl water types along its flow-path. Hydrochemical data also suggest that, groundwater within the basin is primarily undergoing recharge processes involving freshwater mixing with geochemically different ionic signatures than processes involving saline-freshwater mixing. PCA using Varimax with Kaiser Normalization for component matrix has delineated three main processes; i.e. natural geochemical and biochemical processes (water-soil-rock interactions), incongruent dissolution of silicates/aluminosilicates, and pollution of the water resources principally from agricultural inputs. The trace metal results show that, groundwater in some communities within the basin is contaminated, due to natural and anthropogenic sources with Al (19.2 % of boreholes), Se (18.4 % of boreholes), Cd (18.0 % of boreholes), As (11.6 % of boreholes), Pb (39.6 % of boreholes), Mn (5.6 % of boreholes), Hg (42.0 % of boreholes) and Fe (21.6 % of boreholes) concentrations exceeding the WHO (2004) guideline limits for drinking water. Results from the social impact survey

  3. Enhanced biotransformation of TCE using plant terpenoids in contaminated groundwater.

    Science.gov (United States)

    Brown, J R-M; Thompson, I P; Paton, G I; Singer, A C

    2009-12-01

    To examine plant terpenoids as inducers of TCE (trichloroethylene) biotransformation by an indigenous microbial community originating from a plume of TCE-contaminated groundwater. One-litre microcosms of groundwater were spiked with 100 micromol 1(-1) of TCE and amended weekly for 16 weeks with 20 microl 1(-1) of the following plant monoterpenes: linalool, pulegone, R-(+) carvone, S-(-) carvone, farnesol, cumene. Yeast extract-amended and unamended control treatments were also prepared. The addition of R-carvone and S-carvone, linalool and cumene resulted in the biotransformation of upwards of 88% of the TCE, significantly more than the unamendment control (61%). The aforementioned group of terpenes also significantly (P TCE to be degraded than the remaining two terpenes (farnesol and pulegone), and the yeast extract treatment which biotransformed 74-75% of the TCE. The microbial community profile was monitored by denaturing gradient gel electrophoresis and demonstrated much greater similarities between the microbial communities in terpene-amended treatments than in the yeast extract or unamended controls. TCE biotransformation can be significantly enhanced through the addition of selected plant terpenoids. Plant terpenoid and nutrient supplementation to groundwater might provide an environmentally benign means of enhancing the rate of in situ TCE bioremediation.

  4. Status and understanding of groundwater quality in the Sierra Nevada Regional study unit, 2008: California GAMA Priority Basin Project

    Science.gov (United States)

    Fram, Miranda S.; Belitz, Kenneth

    2014-01-01

    Groundwater quality in the Sierra Nevada Regional (SNR) study unit was investigated as part of the California State Water Resources Control Board’s Groundwater Ambient Monitoring and Assessment Program Priority Basin Project. The study was designed to provide statistically unbiased assessments of the quality of untreated groundwater within the primary aquifer system of the Sierra Nevada. The primary aquifer system for the SNR study unit was delineated by the depth intervals over which wells in the State of California’s database of public drinking-water supply wells are open or screened. Two types of assessments were made: (1) a status assessment that described the current quality of the groundwater resource, and (2) an evaluation of relations between groundwater quality and potential explanatory factors that represent characteristics of the primary aquifer system. The assessments characterize untreated groundwater quality, rather than the quality of treated drinking water delivered to consumers by water distributors.

  5. A simplified model of soakaway infiltration interaction with a shallow groundwater table

    DEFF Research Database (Denmark)

    Roldin, Maria; Locatelli, Luca; Mark, Ole

    2013-01-01

    This paper presents a new and simplified modeling concept for soakaway infiltration in the presence of a shallow groundwater table, including representation of the local groundwater mound and its effects on the infiltration rate. The soil moisture retention curve is used to represent the influence......, and its effects on the infiltration rate, can be represented even if the spatial resolution of the groundwater flow model is coarser than the extent of the mound. The new model has been run for a number of scenarios and soil parameters, and the results compared to the output from a two...... of the mound on infiltration rates. The model is intended to be used in situations when distributed urban drainage models with soakaways or similar infiltration devices are coupled to distributed groundwater flow models. With this new modeling concept, the local mounding from small-scale infiltration systems...

  6. Integrating geochemical investigations and geospatial assessment to understand the evolutionary process of hydrochemistry and groundwater quality in arid areas.

    Science.gov (United States)

    El Alfy, Mohamed; Alharbi, Talal; Mansour, Basma

    2018-04-12

    Groundwater is the key for life in arid areas. Aquifer overexploitation and climatic conditions can significantly deteriorate groundwater quality. The Al-Qassim area in central Saudi Arabia is characterized by dense agricultural use and is irrigated mainly by fossil groundwater from the Saq Aquifer. Understanding the area's hydrochemistry, major factors governing groundwater quality, and alternative uses of the groundwater are the main goals of this study. Groundwater samples were collected and examined for major, minor, and trace elements. Ionic relationships, hydrochemical facies, geospatial distributions, and multivariate analyses were conducted to assess the hydrochemical processes at play. The salinity and nitrate concentrations of the Saq Aquifer's groundwater were found to increase in the outcrop areas more than the confined areas. The spatial distributions were fragmented by three main factors: (i) modern recharge by relatively brackish water, (ii) irrigation return flow in intensive farming areas, and (iii) overexploitation and draining of deep and relatively saline zones of the aquifer. Seven water types were found representing the alkaline water with a predominance of sulfate-chloride ions and earth alkaline water with a predominance of sulfate and chloride. Mixing between fresh and brackish water, dissolution of mineral phases, silicate weathering, and reverse ion exchange were recognized as the evolutionary processes, while evaporation played a minor role. Cluster analyses characterized the fresh groundwater zone, modern groundwater recharge zone, and anthropogenic influence zone. In the confined areas, nearly all the groundwater was appropriate for domestic use and irrigation. In the outcrop areas, some limitations were found due to unsuitable conditions.

  7. Evolutionary analysis of groundwater flow: Application of multivariate statistical analysis to hydrochemical data in the Densu Basin, Ghana

    Science.gov (United States)

    Yidana, Sandow Mark; Bawoyobie, Patrick; Sakyi, Patrick; Fynn, Obed Fiifi

    2018-02-01

    An evolutionary trend has been postulated through the analysis of hydrochemical data of a crystalline rock aquifer system in the Densu Basin, Southern Ghana. Hydrochemcial data from 63 groundwater samples, taken from two main groundwater outlets (Boreholes and hand dug wells) were used to postulate an evolutionary theory for the basin. Sequential factor and hierarchical cluster analysis were used to disintegrate the data into three factors and five clusters (spatial associations). These were used to characterize the controls on groundwater hydrochemistry and its evolution in the terrain. The dissolution of soluble salts and cation exchange processes are the dominant processes controlling groundwater hydrochemistry in the terrain. The trend of evolution of this set of processes follows the pattern of groundwater flow predicted by a calibrated transient groundwater model in the area. The data suggest that anthropogenic activities represent the second most important process in the hydrochemistry. Silicate mineral weathering is the third most important set of processes. Groundwater associations resulting from Q-mode hierarchical cluster analysis indicate an evolutionary pattern consistent with the general groundwater flow pattern in the basin. These key findings are at variance with results of previous investigations and indicate that when carefully done, groundwater hydrochemical data can be very useful for conceptualizing groundwater flow in basins.

  8. Hydrochemical and multivariate analysis of groundwater quality in the northwest of Sinai, Egypt.

    Science.gov (United States)

    El-Shahat, M F; Sadek, M A; Salem, W M; Embaby, A A; Mohamed, F A

    2017-08-01

    The northwestern coast of Sinai is home to many economic activities and development programs, thus evaluation of the potentiality and vulnerability of water resources is important. The present work has been conducted on the groundwater resources of this area for describing the major features of groundwater quality and the principal factors that control salinity evolution. The major ionic content of 39 groundwater samples collected from the Quaternary aquifer shows high coefficients of variation reflecting asymmetry of aquifer recharge. The groundwater samples have been classified into four clusters (using hierarchical cluster analysis), these match the variety of total dissolvable solids, water types and ionic orders. The principal component analysis combined the ionic parameters of the studied groundwater samples into two principal components. The first represents about 56% of the whole sample variance reflecting a salinization due to evaporation, leaching, dissolution of marine salts and/or seawater intrusion. The second represents about 15.8% reflecting dilution with rain water and the El-Salam Canal. Most groundwater samples were not suitable for human consumption and about 41% are suitable for irrigation. However, all groundwater samples are suitable for cattle, about 69% and 15% are suitable for horses and poultry, respectively.

  9. Instabilities in power law gradient hardening materials

    DEFF Research Database (Denmark)

    Niordson, Christian Frithiof; Tvergaard, Viggo

    2005-01-01

    Tension and compression instabilities are investigated for specimens with dimensions in the micron range. A finite strain generalization of a higher order strain gradient plasticity theory is implemented in a finite element scheme capable of modeling power law hardening materials. Effects...... of gradient hardening are found to delay the onset of localization under plane strain tension, and significantly reduce strain gradients in the localized zone. For plane strain compression gradient hardening is found to increase the load-carrying capacity significantly....

  10. Status of remedial investigation activities in the Hanford Site 300 Area groundwater operable unit

    International Nuclear Information System (INIS)

    Hulstrom, L.C.; Innis, B.E.; Frank, M.A.

    1993-09-01

    The Phase 1 remedial investigation (RI) and Phase 1 and 2 feasibility studies (FS) for the 300-FF-5 groundwater operable unit underlying the 300 Area on the Hanford Site have been completed. Analysis and evaluation of soil, sediment, and surface water, and biotic sampling data, groundwater chemistry, and radiological data gathered over the past 3 years has been completed. Risk assessment calculations have been performed. Use of the data gathered, coupled with information from an automated water level data collection system, has enabled engineers to track three plumes that represent the most significant contamination of the groundwater

  11. Determination of radon and uranium in the groundwater of Bangalore city

    International Nuclear Information System (INIS)

    Somashekar, R.K.; Davis, Deljo; Jeban Singh, M.; Prakash, K.L.; Shivanna, K.

    2010-01-01

    Groundwater is a precious source of drinking water. Radon and uranium are the naturally occurring radioactive elements in water. The present study attempts to identify the nature of groundwater with respect to the radon and uranium in and around Bangalore city. The radon in groundwater is measured by the integrated instrumental field screening techniques using a radon in air monitor (RAD-7) with attached bubbler. The water after the radon measurement, analysed for the total uranium using ICP- AES. The Radon in water represented in Bq/L and total uranium in μg/L

  12. Effect of land use and urbanization on hydrochemistry and contamination of groundwater from Taejon area, Korea

    Science.gov (United States)

    Jeong, Chan Ho

    2001-11-01

    Taejon Metropolitan City located in the central part of South Korea has grown and urbanized rapidly. The city depends heavily on groundwater as a water resource. Because of ubiquitous pollution sources, the quality and contamination have become important issues for the urban groundwater supply. This study has investigated the chemical characteristics and the contamination of groundwater in relation to land use. An attempt was made to distinguish anthrophogenic inputs from the influence of natural chemical weathering on the chemical composition of groundwater at Taejon. Groundwater samples collected at 170 locations in the Taejon area show very variable chemical composition of groundwater, e.g. electrical conductance ranges from 65 to 1,290 μS/cm. Most groundwater is weakly acidic and the groundwater chemistry is more influenced by land use and urbanization than by aquifer rock type. Most groundwater from green areas and new town residential districts has low electrical conductance, and is of Ca-HCO3 type, whereas the chemical composition of groundwater from the old downtown and industrial district is shifted towards a Ca-Cl (NO3+SO4) type with high electrical conductance. A number of groundwater samples in the urbanized area are contaminated by high nitrate and chlorine, and exhibit high hardness. The EpCO2, that is the CO2 content of a water sample relative to pure water, was computed to obtain more insight into the origin of CO2 and bicarbonate in the groundwater. The CO2 concentration of groundwater in the urbanized area shows a rough positive relationship with the concentration of major inorganic components. The sources of nitrate, chlorine and excess CO2 in the groundwater are likely to be municipal wastes of unlined landfill sites, leaky latrines and sewage lines. Chemical data of commercial mineral water from other Jurassic granite areas were compared to the chemical composition of the groundwater in the Taejon area. Factor analysis of the chemical data

  13. Environmental isotope studies on groundwater problems in the Thar Desert, India

    International Nuclear Information System (INIS)

    Nair, A.R.; Navada, S.V.; Rao, S.M.

    1997-01-01

    One of the groundwater problems encountered in arid areas like the Thar Desert in Rajasthan is to know whether the shallow groundwater is being actively recharged. Environmental isotopes particularly tritium are very useful in providing evidence of recent recharge. In the Barmer area, the shallow groundwaters have tritium levels generally in the range 3-6 TU showing modern recharge. Most of the recharge possibly occurs by direct infiltration of precipitation. Indirect recharge through wadis (river channels) could sometimes be an important mechanism of groundwater recharge. Environmental isotope study in Jalore area showed that the shallow groundwaters near the Sukri river course had δ 2 H and δ 18 O are depleted compared to present day precipitation but not as depleted as the present day Himalayan rivers. Carbon-24 values of some of these groundwaters are in the range of 54-58 pMC showing that they possibly represent old river with headwater connection outside the desert. In the Thar, the deep groundwaters which sometimes form the bulk of water supply are generally paleowaters as sown by environmental δ 2 H, δ 18 O, 3 H and 14 C. For example in the Barmer area, deep groundwaters (depth > 150m) have depleted δ 2 H and δ 18 O compared to the shallow groundwaters and present day precipitation. They have negligible 3 H and 14 C model ages ranging from 4000 to 9500 BP. Hence the isotope data of the deep groundwaters indicate they are paleowaters recharged during humid periods in the Holocene. Over-exploitation of deep groundwaters could lead to mixing of shallow and deep groundwaters or influx of waters from adjoining aquifers. In the Bikaner area similar δ 2 H and δ 18 O of the shallow and deep wells and young waters encountered in some of the deep wells indicated mixing between the two aquifers due to heavy exploitation of groundwaters in the area. In a limestone belt of Jodhpur-Nagaur district heavy exploitation of groundwaters is taking place in the southern

  14. An education gradient in health, a health gradient in education, or a confounded gradient in both?

    Science.gov (United States)

    Lynch, Jamie L; von Hippel, Paul T

    2016-04-01

    There is a positive gradient associating educational attainment with health, yet the explanation for this gradient is not clear. Does higher education improve health (causation)? Do the healthy become highly educated (selection)? Or do good health and high educational attainment both result from advantages established early in the life course (confounding)? This study evaluates these competing explanations by tracking changes in educational attainment and Self-rated Health (SRH) from age 15 to age 31 in the National Longitudinal Study of Youth, 1997 cohort. Ordinal logistic regression confirms that high-SRH adolescents are more likely to become highly educated. This is partly because adolescent SRH is associated with early advantages including adolescents' academic performance, college plans, and family background (confounding); however, net of these confounders adolescent SRH still predicts adult educational attainment (selection). Fixed-effects longitudinal regression shows that educational attainment has little causal effect on SRH at age 31. Completion of a high school diploma or associate's degree has no effect on SRH, while completion of a bachelor's or graduate degree have effects that, though significant, are quite small (less than 0.1 points on a 5-point scale). While it is possible that educational attainment would have greater effect on health at older ages, at age 31 what we see is a health gradient in education, shaped primarily by selection and confounding rather than by a causal effect of education on health. Copyright © 2016 Elsevier Ltd. All rights reserved.

  15. Strain gradient effects in surface roughening

    DEFF Research Database (Denmark)

    Borg, Ulrik; Fleck, N.A.

    2007-01-01

    evidence for strain gradient effects. Numerical analyses of a bicrystal undergoing in-plane tensile deformation are also studied using a strain gradient crystal plasticity theory and also by using a strain gradient plasticity theory for an isotropic solid. Both theories include an internal material length...

  16. Gradient remediability in linear distributed parabolic systems ...

    African Journals Online (AJOL)

    The aim of this paper is the introduction of a new concept that concerned the analysis of a large class of distributed parabolic systems. It is the general concept of gradient remediability. More precisely, we study with respect to the gradient observation, the existence of an input operator (gradient efficient actuators) ensuring ...

  17. Evaluation of a multiport groundwater monitoring system

    International Nuclear Information System (INIS)

    Gilmore, T.J.; Hall, S.H.; Olsen, K.B.; Spane, F.A. Jr.

    1991-03-01

    In 1988 and 1989, Pacific Northwest Laboratory installed a multiport groundwater monitoring system in two wells on the Hanford Site: one near the 216-B-3 Pond in the center of the Hanford Site and one just north of the 300 Area near the Columbia River. The system was installed to provide the US Department of Energy with needed three-dimensional data on the vertical distribution of contaminants and hydraulic heads on the Hanford Site. This study evaluates the ability of the multiport system to obtain hydrogeologic data at multiple points vertically in a single borehole, and addresses the representativeness of the data. Data collected from the two wells indicate that the multiport system is well suited for groundwater monitoring networks requiring three-dimensional characterization of the hydrogeologic system. A network of these systems could provide valuable information on the hydrogeologic environment. However, the advantages of the multiport system diminish when the system is applied to long-term monitoring networks (30+ years) and to deeper wells (<300 ft). For shallow wells, the multiport system provides data in a cost-effective manner that would not be reasonably obtainable with the conventional methods currently in use at the Hanford Site. 17 refs., 28 figs., 6 tabs

  18. SR-Site - sulphide content in the groundwater at Laxemar

    Energy Technology Data Exchange (ETDEWEB)

    Tullborg, E-L (Terralogica, Graabo (Sweden)); Smellie, J. (Conterra, Uppsala (Sweden)); Nilsson, A-Ch (Geosigma, Uppsala (Sweden)); Gimeno, M.J.; Auque, L.F. (Univ. of Zaragoza (Spain)); Wallin, B. (Geokema, Lidingoe (Sweden)); Bruechert, V. (Stockholm Univ. (Sweden)); Molinero, J. (Amphos21, Barcelona (Spain))

    2010-12-15

    Sulphide concentrations in groundwater play a key role in the long term reliability of the metal canisters containing the radioactive waste within a disposal facility for nuclear waste. This is because sulphide in the groundwaters circulating in the vicinity of the deposition tunnels can react with copper in the canisters causing corrosion and therefore reducing their expected lifetime; in a worst case scenario erosion of the bentonite buffer material will expose the canister more rapidly to the fracture groundwater. Sulphide in the groundwater is predominantly microbially produced and thereby controlled by the content of oxidised sulphur sources, organics (carbon sources), reductants (mainly Fe(II), DOC, H{sub 2} and CH{sub 4}), and also flow. In addition, achieved saturation in respect to amorphous Fe-monosulphide will control the possible maximum values and thus limit the Fe2+ and S2- values in the groundwater. The aim of this report is to assess realistic, representative and reliable sulphide groundwater concentrations at present conditions in Laxemar to be considered for use in (future) safety assessments. To achieve this, an evaluation is performed of all the sulphide related data reported from the Laxemar site investigations /Laaksoharju et al. 2009/ and later monitoring campaigns, all of which are stored in the Sicada database. This evaluation shows that values from the Complete Chemical Characterisation (CCC) (i.e. in situ sampling from one or more borehole sections using mobile equipment) are usually lower than those measured during the monitoring phase (i.e. in situ sampling from one borehole section using permanently installed equipment). An exception is borehole KLX01, where values generally lie within the same range as the monitoring samples. For most of the CCC and monitoring sections the last sample in the time series is suggested as representing the 'best possible' sulphide value. When both initial values from CCC (or samples taken with

  19. SR-Site - sulphide content in the groundwater at Laxemar

    International Nuclear Information System (INIS)

    Tullborg, E-L; Smellie, J.; Nilsson, A-Ch; Gimeno, M.J.; Auque, L.F.; Wallin, B.; Bruechert, V.; Molinero, J.

    2010-12-01

    Sulphide concentrations in groundwater play a key role in the long term reliability of the metal canisters containing the radioactive waste within a disposal facility for nuclear waste. This is because sulphide in the groundwaters circulating in the vicinity of the deposition tunnels can react with copper in the canisters causing corrosion and therefore reducing their expected lifetime; in a worst case scenario erosion of the bentonite buffer material will expose the canister more rapidly to the fracture groundwater. Sulphide in the groundwater is predominantly microbially produced and thereby controlled by the content of oxidised sulphur sources, organics (carbon sources), reductants (mainly Fe(II), DOC, H 2 and CH 4 ), and also flow. In addition, achieved saturation in respect to amorphous Fe-monosulphide will control the possible maximum values and thus limit the Fe 2+ and S 2- values in the groundwater. The aim of this report is to assess realistic, representative and reliable sulphide groundwater concentrations at present conditions in Laxemar to be considered for use in (future) safety assessments. To achieve this, an evaluation is performed of all the sulphide related data reported from the Laxemar site investigations /Laaksoharju et al. 2009/ and later monitoring campaigns, all of which are stored in the Sicada database. This evaluation shows that values from the Complete Chemical Characterisation (CCC) (i.e. in situ sampling from one or more borehole sections using mobile equipment) are usually lower than those measured during the monitoring phase (i.e. in situ sampling from one borehole section using permanently installed equipment). An exception is borehole KLX01, where values generally lie within the same range as the monitoring samples. For most of the CCC and monitoring sections the last sample in the time series is suggested as representing the 'best possible' sulphide value. When both initial values from CCC (or samples taken with the hydrotest

  20. Hydrodynamic analysis application of contaminated groundwater remediation to oil hydrocarbons

    Directory of Open Access Journals (Sweden)

    Pajić Predrag R.

    2017-01-01

    Full Text Available In this paper, the application of the hydrodynamic analysis in the selected ‘pumping and treatment’ remediation method of groundwater hydrocarbon pollution in the case of the Pancevo oil refinery is examined. The applied hydrodynamic analysis represents a regular and necessary approach in modern hydrogeology. Previous chemical analysis of soil and groundwater samples at observation objects revealed their pollution by oil products. New researches included the constraction of 12 piezometric boreholes of varying depths, geoelectric soil sounding, ‘in situ’ measurement of the present contaminant, detected as a hydrophobic phase of LNAPL, chemical analysis of soil and groundwater samples with emphasis on total petroleum hydrocarbons (TPH content, total fats and mineral oils, mercury cations and other characteristic compounds, etc. These researches define the volume of contamination issued by the ‘light’ (LNAPL contamination phase. The selected remediation method for this type of pollution is the ‘Pump and Treat’ method, which implies the pumping of contaminated groundwater from aquifer and their subsequent treatment. A hydrodynamic method was used to select the optimal hydrotechnical solution for LNAPL extraction. On the mathematical model, the prediction calculations for two variant solutions were carried out (‘hydraulic isolation’ and complex for the application of groundwater contamination remediation characterized as front pollution substance (by extraction and injection wells or infiltration pool. By extraction wells performing, it would be possible to remove the LNAPL from the surface of the water with special pumps-skimmers. The importance of the hydrodynamic method application is, in addition to the hydrotechnical solution selection for the LNAPL drainage, the provision of quality basis for the dimensioning of these objects based on the results of the groundwater balance.

  1. Redox control of arsenic mobilization in Bangladesh groundwater

    International Nuclear Information System (INIS)

    Zheng, Y.; Stute, M.; Geen, A. van; Gavrieli, I.; Dhar, R.; Simpson, H.J.; Schlosser, P.; Ahmed, K.M.

    2004-01-01

    Detailed hydrochemical measurements, δ 34 S SO4 and 3 H analyses were performed on 37 groundwater samples collected during February 1999, January and March 2000 from 6 locations in eastern and southeastern Bangladesh to examine redox processes that lead to As mobilization in groundwater. The study sites were chosen based on available nation-wide As surveys to span the entire spectrum of As concentrations in Bangladesh groundwater, and to represent 3 of 5 major geological units of the Ganges-Brahmaputra Delta: uplifted Pleistocene terrace, fluvial flood plain and delta plain. Arsenic was found to be mobilized under Fe-reducing conditions in shallow aquifers ( 4 -reducing conditions, suggesting that authigenic sulfide precipitation does not constitute a significant sink for As in these groundwaters. The redox state of the water was characterized by a variety of parameters including dissolved O 2 , NO 3 - , Mn 2+ , Fe 2+ concentrations, and SO 4 2- /Cl - ratios. High dissolved [As] (> 50 μg/l; or > 0.7 μM ) were always accompanied by high dissolved [HCO 3 - ] (> 4 mM), and were close to saturation with respect to calcite. Groundwater enriched in As (200-800 μg/l; or 2.7-10.7 μM) and phosphate (30-100 μM) but relatively low in dissolved Fe (5-40 μM) probably resulted from re-oxidation of reducing, As and Fe enriched water. This history was deduced from isotopic signatures of δ 34 S SO4 and 3 H 2 O ( 3 H) to delineate the nature of redox changes for some of the reducing groundwaters. In contrast, As is not mobilized in presumed Pleistocene aquifers, both shallow (30-60 m) and deep (150-270 m), because conditions were not reducing enough due to lack of sufficient O 2 demand

  2. Groundwater dynamics in mountain peatlands with contrasting climate, vegetation, and hydrogeological setting

    Science.gov (United States)

    Millar, David J.; Cooper, David J.; Ronayne, Michael J.

    2018-06-01

    Hydrological dynamics act as a primary control on ecosystem function in mountain peatlands, serving as an important regulator of carbon fluxes. In western North America, mountain peatlands exist in different hydrogeological settings, across a range climatic conditions, and vary in floristic composition. The sustainability of these ecosystems, particularly those at the low end of their known elevation range, is susceptible to a changing climate via changes in the water cycle. We conducted a hydrological investigation of two mountain peatlands, with differing vegetation, hydrogeological setting (sloping vs basin), and climate (strong vs weak monsoon influence). Growing season saturated zone water budgets were modeled on a daily basis, and subsurface flow characterizations were performed during multiple field campaigns at each site. The sloping peatland expectedly showed a strong lateral groundwater potential gradient throughout the growing season. Alternatively, the basin peatland had low lateral gradients but more pronounced vertical gradients. A zero-flux plane was apparent at a depth of approximately 50 cm below the peat surface at the basin peatland; shallow groundwater above this depth moved upward towards the surface via evapotranspiration. The differences in groundwater flow dynamics between the two sites also influenced water budgets. Higher groundwater inflow at the sloping peatland offset higher rates of evapotranspiration losses from the saturated zone, which were apparently driven by differences in vegetative cover. This research revealed that although sloping peatlands cover relatively small portions of mountain watersheds, they provide unique settings where vegetation directly utilizes groundwater for transpiration, which were several-fold higher than typically reported for surrounding uplands.

  3. 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

  4. 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

  5. Ecosystem-groundwater interactions under changing land uses: Linking water, salts, and carbon across central Argentina

    Science.gov (United States)

    Jobbagy, E. G.; Nosetto, M. D.; Santoni, C. S.; Jackson, R. B.

    2007-05-01

    Although most ecosystems display a one-way connection with groundwater based on the regulation of deep water drainage (recharge), this link can become reciprocal when the saturated zone is shallow and plants take up groundwater (discharge). In what context is the reciprocal link most likely? How is it affected by land use changes? Has it consequences on salt and carbon cycling? We examine these questions across a precipitation gradient in the Pampas and Espinal of Argentina focusing on three vegetation change situations (mean annual rainfall): afforestation of humid (900-1300 mm) and subhumid grassland (700-900 mm/yr of rainfall), annual cultivation of subhumid grasslands (700-800 mm/yr), and annual cultivation of semiarid forests (500-700 mm). Humid and subhumid grasslands have shallow (measurements. Groundwater contributions enhance carbon uptake in plantations compared to grasslands as suggested by aboveground biomass measurements and satellite vegetation indexes from sites with and without access to groundwater. Where rainfall is 15 m deep) and recharge under natural conditions is null. The establishment of crops, however, triggers the onset of recharge, as evidenced by vadose zones getting wetter and leached of atmospheric chloride. Cropping may cause water table raises leading to a two-way coupling of ecosystems and groundwater in the future, as it has been documented for similar settings in Australia and the Sahel. In the Pampas land use change interacts with groundwater consumption leading to higher carbon uptake (humid and subhumid grasslands) and salt accumulation (subhumid grasslands). In the Espinal (semiarid forest) land use change currently involves a one-way effect on groundwater recharge that may switch to a reciprocal connection if regional water table raises occur. Neglecting the role of groundwater in flat sedimentary plains can obscure our understanding of carbon and salt cycling and curtail our attempts to sustain soil and water resources under

  6. Septic Systems Contribution to Phosphorus in Shallow Groundwater: Field-Scale Studies Using Conventional Drainfield Designs

    Science.gov (United States)

    Mechtensimer, Sara

    2017-01-01

    Septic systems can be a potential source of phosphorus (P) in groundwater and contribute to eutrophication in aquatic systems. Our objective was to investigate P transport from two conventional septic systems (drip dispersal and gravel trench) to shallow groundwater. Two new in-situ drainfields (6.1 m long by 0.61 m wide) with a 3.72 m2 infiltrative surface were constructed. The drip dispersal drainfield was constructed by placing 30.5 cm commercial sand on top of natural soil and the gravel trench drainfield was constructed by placing 30.5 cm of gravel on top of 30.5 cm commercial sand and natural soil. Suction cup lysimeters were installed in the drainfields (at 30.5, 61, 106.7 cm below infiltrative surface) and piezometers were installed in the groundwater (>300 cm below infiltrative surface) to capture P dynamics from the continuum of unsaturated to saturated zones in the septic systems. Septic tank effluent (STE), soil-water, and groundwater samples were collected for 64 events (May 2012–Dec 2013) at 2 to 3 days (n = 13), weekly (n = 29), biweekly (n = 17), and monthly (n = 5) intervals. One piezometer was installed up-gradient of the drainfields to monitor background groundwater (n = 15). Samples were analyzed for total P (TP), orthophosphate-P (PO4–P), and other–P (TP—PO4-P). The gravel trench drainfield removed significantly (p300 cm in the groundwater, both systems had similar TP reductions of >97%. After 18 months of STE application, there was no significant increase in groundwater TP concentrations in both systems. We conclude that both drainfield designs are effective at reducing P transport to shallow groundwater. PMID:28107505

  7. Septic Systems Contribution to Phosphorus in Shallow Groundwater: Field-Scale Studies Using Conventional Drainfield Designs.

    Directory of Open Access Journals (Sweden)

    Sara Mechtensimer

    Full Text Available Septic systems can be a potential source of phosphorus (P in groundwater and contribute to eutrophication in aquatic systems. Our objective was to investigate P transport from two conventional septic systems (drip dispersal and gravel trench to shallow groundwater. Two new in-situ drainfields (6.1 m long by 0.61 m wide with a 3.72 m2 infiltrative surface were constructed. The drip dispersal drainfield was constructed by placing 30.5 cm commercial sand on top of natural soil and the gravel trench drainfield was constructed by placing 30.5 cm of gravel on top of 30.5 cm commercial sand and natural soil. Suction cup lysimeters were installed in the drainfields (at 30.5, 61, 106.7 cm below infiltrative surface and piezometers were installed in the groundwater (>300 cm below infiltrative surface to capture P dynamics from the continuum of unsaturated to saturated zones in the septic systems. Septic tank effluent (STE, soil-water, and groundwater samples were collected for 64 events (May 2012-Dec 2013 at 2 to 3 days (n = 13, weekly (n = 29, biweekly (n = 17, and monthly (n = 5 intervals. One piezometer was installed up-gradient of the drainfields to monitor background groundwater (n = 15. Samples were analyzed for total P (TP, orthophosphate-P (PO4-P, and other-P (TP-PO4-P. The gravel trench drainfield removed significantly (p300 cm in the groundwater, both systems had similar TP reductions of >97%. After 18 months of STE application, there was no significant increase in groundwater TP concentrations in both systems. We conclude that both drainfield designs are effective at reducing P transport to shallow groundwater.

  8. Groundwater response to heavy precipitation

    International Nuclear Information System (INIS)

    Waring, C.; Bradd, J.; Hankin, S.

    2003-05-01

    An investigation of the groundwater response to heavy rainfall at Lucas Heights Science and Technology Centre (LHSTC) is required under the conditions of Facility Licence F0001 for the ANSTO's Replacement Research Reactor. Groundwater continuous hydrograph monitoring has been used for this purpose. Hydrograph data from four boreholes are presented showing the rainfall recorded during the same period for comparison. The drought conditions have provided only limited cases where groundwater responded to a rainfall event. The characteristic response was local, caused by saturated soil contributing water directly to the borehole and the falling head as the water was redistributed into he aquifer in a few hours. Hydrograph data from borehole near the head of a gully showed that groundwater flow from the plateau to the gully produced a peak a fe days after the rainfall event and that the water level returned to its original level after about 10 days. The hydrograph data are consistent with an imperfect multi-layer groundwater flow regime, developed from earlier seismic and geophysical data, with decreasing rate of flow in each layer due to decreasing hydraulic conductivity with depth. The contrast in hydraulic conductivity between the thin permeable soil layer and the low permeable sandstone forms an effective barrier to vertical flow

  9. Bank storage buffers rivers from saline regional groundwater: an example from the Avon River Australia

    Science.gov (United States)

    Gilfedder, Benjamin; Hofmann, Harald; Cartwrighta, Ian

    2014-05-01

    Groundwater-surface water interactions are often conceptually and numerically modeled as a two component system: a groundwater system connected to a stream, river or lake. However, transient storage zones such as hyporheic exchange, bank storage, parafluvial flow and flood plain storage complicate the two component model by delaying the release of flood water from the catchment. Bank storage occurs when high river levels associated with flood water reverses the hydraulic gradient between surface water and groundwater. River water flows into the riparian zone, where it is stored until the flood water recede. The water held in the banks then drains back into the river over time scales ranging from days to months as the hydraulic gradient returns to pre-flood levels. If the frequency and amplitude of flood events is high enough, water held in bank storage can potentially perpetually remain between the regional groundwater system and the river. In this work we focus on the role of bank storage in buffering river salinity levels against saline regional groundwater on lowland sections of the Avon River, Victoria, Australia. We hypothesize that the frequency and magnitude of floods will strongly influence the salinity of the stream water as banks fill and drain. A bore transect (5 bores) was installed perpendicular to the river and were instrumented with head and electrical conductivity loggers measuring for two years. We also installed a continuous 222Rn system in one bore. This data was augmented with long-term monthly EC from the river. During high rainfall events very fresh flood waters from the headwaters infiltrated into the gravel river banks leading to a dilution in EC and 222Rn in the bores. Following the events the fresh water drained back into the river as head gradients reversed. However the bank water salinities remained ~10x lower than regional groundwater levels during most of the time series, and only slightly above river water. During 2012 SE Australia

  10. Temperature Gradient in Hall Thrusters

    International Nuclear Information System (INIS)

    Staack, D.; Raitses, Y.; Fisch, N.J.

    2003-01-01

    Plasma potentials and electron temperatures were deduced from emissive and cold floating probe measurements in a 2 kW Hall thruster, operated in the discharge voltage range of 200-400 V. An almost linear dependence of the electron temperature on the plasma potential was observed in the acceleration region of the thruster both inside and outside the thruster. This result calls into question whether secondary electron emission from the ceramic channel walls plays a significant role in electron energy balance. The proportionality factor between the axial electron temperature gradient and the electric field is significantly smaller than might be expected by models employing Ohmic heating of electrons

  11. Generalized Gradient Approximation Made Simple

    International Nuclear Information System (INIS)

    Perdew, J.P.; Burke, K.; Ernzerhof, M.

    1996-01-01

    Generalized gradient approximations (GGA close-quote s) for the exchange-correlation energy improve upon the local spin density (LSD) description of atoms, molecules, and solids. We present a simple derivation of a simple GGA, in which all parameters (other than those in LSD) are fundamental constants. Only general features of the detailed construction underlying the Perdew-Wang 1991 (PW91) GGA are invoked. Improvements over PW91 include an accurate description of the linear response of the uniform electron gas, correct behavior under uniform scaling, and a smoother potential. copyright 1996 The American Physical Society

  12. Concentrations and speciation of arsenic along a groundwater flow-path in the Upper Floridan aquifer, Florida, USA

    Science.gov (United States)

    Haque, S. E.; Johannesson, K. H.

    2006-05-01

    Arsenic (As) concentrations and speciation were determined in groundwaters along a flow-path in the Upper Floridan aquifer (UFA) to investigate the biogeochemical “evolution“ of As in this relatively pristine aquifer. Dissolved inorganic As species were separated in the field using anion-exchange chromatography and subsequently analyzed by inductively coupled plasma mass spectrometry. Total As concentrations are higher in the recharge area groundwaters compared to down-gradient portions of UFA. Redox conditions vary from relatively oxic to anoxic along the flow-path. Mobilization of As species in UFA groundwaters is influenced by ferric iron reduction and subsequent dissolution, sulfate reduction, and probable pyrite precipitation that are inferred from the data to occur along distinct regions of the flow-path. In general, the distribution of As species are consistent with equilibrium thermodynamics, such that arsenate dominates in more oxidizing waters near the recharge area, and arsenite predominates in the progressively reducing groundwaters beyond the recharge area.

  13. Estimation of groundwater recharge in sedimentary rock aquifer systems in the Oti basin of Gushiegu District, Northern Ghana

    Science.gov (United States)

    Afrifa, George Yamoah; Sakyi, Patrick Asamoah; Chegbeleh, Larry Pax

    2017-07-01

    Sustainable development and the management of groundwater resources for optimal socio-economic development constitutes one of the most effective strategies for mitigating the effects of climate change in rural areas where poverty is a critical cause of environmental damage. This research assessed groundwater recharge and its spatial and temporal variations in Gushiegu District in the Northern Region of Ghana, where groundwater is the main source of water supply for most uses. Isotopic data of precipitation and groundwater were used to infer the origin of groundwater and the possible relationship between groundwater and surface water in the partially metamorphosed sedimentary aquifer system in the study area. Though the data do not significantly establish strong relation between groundwater and surface water, the study suggests that groundwater in the area is of meteoric origin. However, the data also indicate significant enrichment of the heavy isotopes (18O and 2H) in groundwater relative to rainwater in the area. The Chloride Mass Balance (CMB) and Water Table Fluctuations (WTF) techniques were used to quantitatively estimate the groundwater recharge in the area. The results suggest groundwater recharge in a range of 13.9 mm/y - 218 mm/y, with an average of 89 mm/yr, representing about 1.4%-21.8% (average 8.9%) of the annual precipitation in the area. There is no clearly defined trend in the temporal variations of groundwater recharge in the area, but the spatial variations are discussed in relation to the underlying lithologies. The results suggest that the fraction of precipitation that reaches the saturated zone as groundwater recharge is largely controlled by the vertical hydraulic conductivities of the material of the unsaturated zone. The vertical hydraulic conductivity coupled with humidity variations in the area modulates the vertical infiltration and percolation of precipitation.

  14. Dai-Kou type conjugate gradient methods with a line search only using gradient.

    Science.gov (United States)

    Huang, Yuanyuan; Liu, Changhe

    2017-01-01

    In this paper, the Dai-Kou type conjugate gradient methods are developed to solve the optimality condition of an unconstrained optimization, they only utilize gradient information and have broader application scope. Under suitable conditions, the developed methods are globally convergent. Numerical tests and comparisons with the PRP+ conjugate gradient method only using gradient show that the methods are efficient.

  15. Geospatial Data Management Platform for Urban Groundwater

    Science.gov (United States)

    Gaitanaru, D.; Priceputu, A.; Gogu, C. R.

    2012-04-01

    Due to the large amount of civil work projects and research studies, large quantities of geo-data are produced for the urban environments. These data are usually redundant as well as they are spread in different institutions or private companies. Time consuming operations like data processing and information harmonisation represents the main reason to systematically avoid the re-use of data. The urban groundwater data shows the same complex situation. The underground structures (subway lines, deep foundations, underground parkings, and others), the urban facility networks (sewer systems, water supply networks, heating conduits, etc), the drainage systems, the surface water works and many others modify continuously. As consequence, their influence on groundwater changes systematically. However, these activities provide a large quantity of data, aquifers modelling and then behaviour prediction can be done using monitored quantitative and qualitative parameters. Due to the rapid evolution of technology in the past few years, transferring large amounts of information through internet has now become a feasible solution for sharing geoscience data. Furthermore, standard platform-independent means to do this have been developed (specific mark-up languages like: GML, GeoSciML, WaterML, GWML, CityML). They allow easily large geospatial databases updating and sharing through internet, even between different companies or between research centres that do not necessarily use the same database structures. For Bucharest City (Romania) an integrated platform for groundwater geospatial data management is developed under the framework of a national research project - "Sedimentary media modeling platform for groundwater management in urban areas" (SIMPA) financed by the National Authority for Scientific Research of Romania. The platform architecture is based on three components: a geospatial database, a desktop application (a complex set of hydrogeological and geological analysis

  16. Technetium and neptunium reactions in basalt/groundwater systems

    International Nuclear Information System (INIS)

    Meyer, R.E.; Arnold, W.D.; Kelmers, A.D.; Kessler, J.H.; Clark, R.J.; Johnson, J.S. Jr.; Young, G.C.; Case, F.I.; Westmoreland, C.G.

    1985-01-01

    Sorption isotherms and apparent concentration limits for Tc(VII) and Np(V) for a variety of groundwater/basalt systems were determined using Grande Ronde basalt samples representative of the Hanford Site candidate high-level waste repository. Under oxic redox conditions (air present), little or no sorption of technetium was observed; neptunium exhibited low to moderate sorption ratios. Under anoxic redox conditions (oxygen-free), low to moderate sorption of technetium was often observed, but the extent of sorption was highly dependent upon the groundwater composition and the method of pretreatment (if any) of the basalt. Sorption isotherms for technetium under reducing redox conditions (hydrazine added) indicate an apparent concentration limit of approximately 10 -6 mol/l Tc. No apparent concentration limit was found for neptunium for concentrations in groundwater up to 10 -6 mol/l and 8 x 10 -7 mol/l under oxic and reducing (hydrazine added) redox conditions, respectively. Valence control and valence analysis experiments suggest that the sorption or precipitation of Tc and Np from groundwater in the presence of basalt may result from a heterogeneous reaction occurring on the surface of the basalt. One of the critical factors of this reduction reaction appears to be the accessibility of the reactive ferrous iron component of the basalt. The laboratory simulation of groundwater redox conditions representative of the repository environment through the use of solution phase redox reagents is of questionable validity, and information obtained by such experimental methods may not be defensible for site performance assessment calculations. Anoxic experiments conducted in an argon-filled glove box appear better suited for the laboratory simulation of in situ redox conditions. 15 references, 6 figures

  17. Technetium and neptunium reactions in basalt/groundwater systems

    International Nuclear Information System (INIS)

    Meyer, R.E.; Arnold, W.D.; Kelmers, A.D.; Kessler, J.H.; Clark, R.J.; Johnson, J.S. Jr.; Young, G.C.; Case, F.I.; Westmoreland, C.G.; Florida State Univ., Tallahassee)

    1984-01-01

    Sorption isotherms and apparent concentration limits for Tc(VII) and Np(V) for a variety of groundwater/basalt systems were determined using Grande Ronde basalt samples representative of the Hanford Site candidate high-level waste repository. Under oxic redox conditions (air present), little or no sorption of technetium was observed; neptunium exhibited low to moderate sorption ratios. Under anoxic redox conditions (oxygen-free), low to moderate sorption of technetium was often observed, but the extent of sorption was highly dependent upon the groundwater composition and the method of pretreatment (if any) of the basalt. Sorption isotherms for technetium under reducing redox conditions (hydrazine added) indicate an apparent concentration limit of approximately 10 -6 mol/L Tc. No apparent concentration limit was found for neptunium for concentrations in groundwater up to approx. 10 -6 mol/L and 8 x 10 -7 mol/L under oxic and reducing (hydrazine added) redox conditions, respectively. Valence control and valence analysis experiments suggest that the sorption or precipitation of Tc and Np from groundwater in the presence of basalt may result from a heterogeneous reaction occurring on the surface of the basalt. One of the critical factors of this reduction reaction appears to be the accessibility of the reactive ferrous iron component of the basalt. The laboratory simulation of groundwater redox conditions representative of the repository environment through the use of solution phase redox reagents is of questionable validity, and information obtained by such experimental methods may not be defensible for site performance assessment calculations. Anoxic experiments conducted in an argon-filled glove box appear better suited for the laboratory simulation of in situ redox conditions. 15 refs., 6 tabs

  18. Ternary gradient metal-organic frameworks.

    Science.gov (United States)

    Liu, Chong; Rosi, Nathaniel L

    2017-09-08

    Gradient MOFs contain directional gradients of either structure or functionality. We have successfully prepared two ternary gradient MOFs based on bMOF-100 analogues, namely bMOF-100/102/106 and bMOF-110/100/102, via cascade ligand exchange reactions. The cubic unit cell parameter discrepancy within an individual ternary gradient MOF crystal is as large as ∼1 nm, demonstrating the impressive compatibility and flexibility of the component MOF materials. Because of the presence of a continuum of unit cells, the pore diameters within individual crystals also change in a gradient fashion from ∼2.5 nm to ∼3.0 nm for bMOF-100/102/106, and from ∼2.2 nm to ∼2.7 nm for bMOF-110/100/102, indicating significant porosity gradients. Like previously reported binary gradient MOFs, the composition of the ternary gradient MOFs can be easily controlled by adjusting the reaction conditions. Finally, X-ray diffraction and microspectrophotometry were used to analyse fractured gradient MOF crystals by comparing unit cell parameters and absorbance spectra at different locations, thus revealing the profile of heterogeneity (i.e. gradient distribution of properties) and further confirming the formation of ternary gradient MOFs.

  19. 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

  20. Investigation of Arsenotrophic Microbiome in Arsenic-Affected Bangladesh Groundwater.

    Science.gov (United States)

    Sultana, Munawar; Mou, Taslin Jahan; Sanyal, Santonu Kumar; Diba, Farzana; Mahmud, Zahid Hayat; Parvez, Anowar Khasru; Hossain, M Anwar

    2017-09-01

    Arsenotrophic bacteria contribute to the nutrient cycling in arsenic (As) affected groundwater. This study employed a culture-independent and -dependent investigation of arsenotrophic microbiomes in As affected groundwater samples collected from Madhabpur, Sonatengra, and Union Porishod in Singair Upazila, Manikganj, Bangladesh. Total As contents, detected by Atomic Absorption Spectrophotometry (AAS) of the samples, were 47 µg/L (Madhabpur, SNGW-1), 53 µg/L (Sonatengra, SNGW-2), and 12 µg/L (Union porishod, SNGW-3), whereas the control well (SNGW-4; depths >150 m) showed As content of 6 µg/L. Denaturing Gradient Gel Electrophoresis (DGGE) analysis of the amplified 16S rRNA gene from As-affected groundwater samples revealed the dominance of aerobic bacteria Pseudomonas within heterogeneous bacterial populations. DGGE of heterotrophic enrichments supplemented with arsenite [As (III)] for 4 weeks showed the dominance of Chryseobacterium, Flavobacterium, and Aquabacterium, whereas the dominant genera in that of autotrophic enrichments were Aeromonas, Acinetobacter, and Pseudomonas. Cultured bacteria retrieved from both autotrophic and heterotrophic enrichments were distinguished into nine genotypes belonging to Chryseobacterium, Acinetobacter, Escherichia, Pseudomonas, Stenotrophomonas, Janibacter, Staphylococcus, and Bacillus. They exhibited varying range of As(III) tolerance from 4 to 27 mM. As(III) transformation potential was confirmed within the isolates with oxidation rate as high as 0.143 mM/h for Pseudomonas sp. Sn 28. The arsenotrophic microbiome specifies their potential role in groundwater As-cycling and their genetic information provide the scientific basis for As-bioremediation. © 2017, National Ground Water Association.

  1. REMEDIATION OF NITRATE-CONTAMINATED GROUNDWATER USING A BIOBARRIER

    International Nuclear Information System (INIS)

    STrietelmeir, B.

    2000-01-01

    A biobarrier system has been developed for use in remediating shallow alluvial groundwater. This barrier is made from highly porous materials that are relatively long-lasting, carbon-based (to supply a limiting nutrient in nitrate destruction, in most cases), and extremely inexpensive and easy to emplace. In a series of laboratory studies, we have determined the effectiveness of this barrier at destroying nitrate and perchlorate in groundwater from Mortandad Canyon at Los Alamos National Laboratory (LANL). This groundwater was obtained from a monitoring well, MCO-5, which is located in the flowpath of the discharge waters from the LANL Radioactive Liquid Waste Treatment Facility (RLWTF). Water with elevated nitrate levels has been discharged from this plant for many years, until recently when the nitrate levels have been brought under the discharge limits. However, the historical discharge has resulted in a nitrate plume in the alluvial groundwater in this canyon. The LANL Multi-Barrier project was initiated this past year to develop a system of barriers that would prevent the transport of radionuclides, metals, colloids and other contaminants, including nitrate and perchlorate, further down the canyon in order to protect populations down-gradient. The biobarrier. will be part of this Multi-Barrier system. We have demonstrated the destruction of nitrate at levels up to 6.5-9.7 mhl nitrate (400-600 mg/L), and that of perchlorate at levels of about 4.3 microM perchlorate (350 ppb). We have quantified the populations of microorganisms present in the biofilm that develops on the biobarrier. The results of this research will be discussed along with other potential applications of this system

  2. Groundwater recharge patterns in the Yobe river Fadama: evidence from hydrochemistry

    International Nuclear Information System (INIS)

    Agbo, J.U.; Alkali, S.C.; Nwaiwu, M. O.

    1998-01-01

    Twenty Groundwater monitor Piezometers installed linearly away from the channel of River Yobe, on opposing banks were monitored across the rainy and dry seasons of 1993. Results indicate that water levels rose rapidly in July attaining levels above ground surface in September, and by October the water level was at the decline. These coincided with the advance and the retreat of the Yobe River flood, suggestive of the Yobe River having a significant influence on the recharge to the alluvial aquifers of the Fadama. Results of chemical analyses of water samples collected from the piezometers, river water, and flood water, suggest that groundwater of the shallow alluvial aquifers do not seem to have a common immediate source with the surface water sources of the Fadama. Hydrochemical concentration trend show concentration gradient towards the river channel, implying that the river might not be the source of the groundwater recharge to the Yobe River Fadama aquifers. Groundwater flow characteristics, also seem to support this view, since there is flow gradient towards the river for the greater part of the year except during peak flood when there are indications of flow (by way of higher potentiometric surface) away from the river. These and other evidences discussed in the paper suggest that the Fadama alluvial aquifer gets most of its recharge directly from rainfall infiltration in regions devoid of clay cover

  3. Evaluation of Groundwater Pollution with Heavy Metals at the Oblogo No.1 Dumpsite in Accra, Ghana

    Directory of Open Access Journals (Sweden)

    Kodwo Beedu Keelson

    2014-07-01

    Full Text Available The aim of this research study was to evaluate the groundwater pollution risks from heavy metal contaminants near the de-commissioned Oblogo No.1 dumpsite using a combination of USEPA leachate estimation and migration models. The Hydraulic Evaluation of Landfill Performance (HELP model was used to determine leachate volumes from the base of the dumpsite whereas the Industrial Waste Evaluation Model (IWEM was used to determine contaminant concentrations at groundwater wells located at various distances from the dumpsite. It was observed that there is a wide variation in the concentration of the contaminants measured at different sampling periods between 2004 and 2011. Pollution risks from chromium, lead, manganese, cobalt and zinc were determined to be very low since the simulated contaminant concentrations in the wells were less than the reference ground water concentrations. However, the concentrations of cadmium, copper and arsenic were determined to be high enough to constitute a potential risk to groundwater wells which are down-gradient of the dumpsite. It was also determined that the minimum buffer distance of 360 m specified in the Ghana Landfill Guidelines may not ensure adequate protection for groundwater wells located down-gradient of the Oblogo No.1 dumpsite.

  4. Impact of hydrogeological factors on groundwater salinization due to ocean-surge inundation

    Science.gov (United States)

    Yang, Jie; Zhang, Huichen; Yu, Xuan; Graf, Thomas; Michael, Holly A.

    2018-01-01

    Ocean surges cause seawater inundation of coastal inland areas. Subsequently, seawater infiltrates into coastal aquifers and threatens the fresh groundwater resource. The severity of resulting salinization can be affected by hydrogeological factors including aquifer properties and hydrologic conditions, however, little research has been done to assess these effects. To understand the impacts of hydrogeological factors on groundwater salinization, we numerically simulated an ocean-surge inundation event on a two-dimensional conceptual coastal aquifer using a coupled surface-subsurface approach. We varied model permeability (including anisotropy), inland hydraulic gradient, and recharge rate. Three salinization-assessment indicators were developed, based on flushing time, depth of salt penetration, and a combination of the two, weighted flushing time, with which the impact of hydrogeological factors on groundwater vulnerability to salinization were quantitatively assessed. The vulnerability of coastal aquifers increases with increasing isotropic permeability. Low horizontal permeability (kx) and high vertical permeability (kz) lead to high aquifer vulnerability, and high kx and low kz lead to low aquifer vulnerability. Vulnerability decreases with increasing groundwater hydraulic gradient and increasing recharge rate. Additionally, coastal aquifers with a low recharge rate (R ≤ 300 mm yr-1) may be highly vulnerable to ocean-surge inundation. This study shows how the newly introduced indicators can be used to quantitatively assess coastal aquifer vulnerability. The results are important for global vulnerability assessment of coastal aquifers to ocean-surge inundation.

  5. 85Kr dating of groundwater

    International Nuclear Information System (INIS)

    Rozanski, K.; Florkowski, T.

    1978-01-01

    The possibility of 85 Kr dating of groundwater is being investigated. The method of gas extraction from 200 to 300 litres of water sample has been developed. The Argon and Krypton mixture, separated from the gas extracted from water, was counted in a 1.5 ml volume proportional counter. The amount of krypton gas in the counter was determined by mass spectrometry. A number of surface and groundwater samples were analyzed indicating an 85 Kr concentration ranging from present atmospheric content (river water) to zero values. 85 Kr 'blank value' was determined to be about 5 per cent of present 85 Kr atmospheric content. For groundwater samples, the mean residence time in the system was calculated assuming the exponential model and known 85 Kr input function. Further improvement of the method should bring higher yield of krypton separation and lower volume of water necessary for analysis. (orig.) [de

  6. Groundwater arsenic contamination throughout China.

    Science.gov (United States)

    Rodríguez-Lado, Luis; Sun, Guifan; Berg, Michael; Zhang, Qiang; Xue, Hanbin; Zheng, Quanmei; Johnson, C Annette

    2013-08-23

    Arsenic-contaminated groundwater used for drinking in China is a health threat that was first recognized in the 1960s. However, because of the sheer size of the country, millions of groundwater wells remain to be tested in order to determine the magnitude of the problem. We developed a statistical risk model that classifies safe and unsafe areas with respect to geogenic arsenic contamination in China, using the threshold of 10 micrograms per liter, the World Health Organization guideline and current Chinese standard for drinking water. We estimate that 19.6 million people are at risk of being affected by the consumption of arsenic-contaminated groundwater. Although the results must be confirmed with additional field measurements, our risk model identifies numerous arsenic-affected areas and highlights the potential magnitude of this health threat in China.

  7. Geoelectrical mapping and groundwater contamination

    Science.gov (United States)

    Blum, Rainer

    Specific electrical resistivity of near-surface materials is mainly controlled by the groundwater content and thus reacts extremely sensitive to any change in the ion content. Geoelectric mapping is a well-established, simple, and inexpensive technique for observing areal distributions of apparent specific electrical resistivities. These are a composite result of the true resistivities in the underground, and with some additional information the mapping of apparent resistivities can help to delineate low-resistivity groundwater contaminations, typically observed downstream from sanitary landfills and other waste sites. The presence of other good conductors close to the surface, mainly clays, is a serious noise source and has to be sorted out by supporting observations of conductivities in wells and geoelectric depth soundings. The method may be used to monitor the extent of groundwater contamination at a specific time as well as the change of a contamination plume with time, by carrying out repeated measurements. Examples for both are presented.

  8. Strain gradient effects on cyclic plasticity

    DEFF Research Database (Denmark)

    Niordson, Christian Frithiof; Legarth, Brian Nyvang

    2010-01-01

    Size effects on the cyclic shear response are studied numerically using a recent higher order strain gradient visco-plasticity theory accounting for both dissipative and energetic gradient hardening. Numerical investigations of the response under cyclic pure shear and shear of a finite slab between...... rigid platens have been carried out, using the finite element method. It is shown for elastic–perfectly plastic solids how dissipative gradient effects lead to increased yield strength, whereas energetic gradient contributions lead to increased hardening as well as a Bauschinger effect. For linearly...... hardening materials it is quantified how dissipative and energetic gradient effects promote hardening above that of conventional predictions. Usually, increased hardening is attributed to energetic gradient effects, but here it is found that also dissipative gradient effects lead to additional hardening...

  9. Hydrogeochemical analysis and quality evaluation of groundwater ...

    African Journals Online (AJOL)

    GREG

    2013-05-08

    May 8, 2013 ... Department of Geology and Exploration Geophysics, Ebonyi State University, P.M.B. 053, Abakaliki,. Ebonyi State .... classify the chemistry of groundwater in hard rock, ... Occurrence, movement and storage of groundwater.

  10. A proposed groundwater management framework for municipalities ...

    African Journals Online (AJOL)

    A proposed groundwater management framework for municipalities in South Africa. ... Hence, the Water Research Commission (WRC) has commissioned a project ... and available tools to achieve sustainable groundwater management reflect ...

  11. Hydrogeological characterization and assessment of groundwater ...

    Indian Academy of Sciences (India)

    In this perspective, assessment of groundwater quality in shallow aquifers in vicinity of the ... contributes about 60% of the total wastewater that gets discharged from ...... tern and effective groundwater management; Proc. Indian. Nat. Sci. Acad.

  12. Deciphering groundwater quality for irrigation and domestic

    Indian Academy of Sciences (India)

    Groundwater quality; irrigation and domestic suitability; ionic balance, Suri I and II ... is important for groundwater planning and management in the study area. ... total hardness (TH), Piper's trilinear diagram and water quality index study.

  13. Planning for groundwater in South Africa

    CSIR Research Space (South Africa)

    Maherry, A

    2010-09-01

    Full Text Available Ecosystems that rely on groundwater as a water source have a natural and inherent resilience to climate change. Under natural conditions aquifers are stable water sources – in fact, ecosystems reliant on groundwater are literally the refuge...

  14. Spatial control of groundwater contamination, using principal

    Indian Academy of Sciences (India)

    Spatial control of groundwater contamination, using principal component analysis ... anthropogenic (agricultural activities and domestic wastewaters), and marine ... The PC scores reflect the change of groundwater quality of geogenic origin ...

  15. Groundwater pollution: are we monitoring appropriate parameters?

    CSIR Research Space (South Africa)

    Tredoux, G

    2004-01-01

    Full Text Available Groundwater pollution is a worldwide phenomenon with potentially disastrous consequences. Prevention of pollution is the ideal approach. However, in practice groundwater quality monitoring is the main tool for timely detection of pollutants...

  16. Study on uncertainty evaluation methodology related to hydrological parameter of regional groundwater flow analysis model

    International Nuclear Information System (INIS)

    Sakai, Ryutaro; Munakata, Masahiro; Ohoka, Masao; Kameya, Hiroshi

    2009-11-01

    In the safety assessment for a geological disposal of radioactive waste, it is important to develop a methodology for long-term estimation of regional groundwater flow from data acquisition to numerical analyses. In the uncertainties associated with estimation of regional groundwater flow, there are the one that concerns parameters and the one that concerns the hydrologeological evolution. The uncertainties of parameters include measurement errors and their heterogeneity. The authors discussed the uncertainties of hydraulic conductivity as a significant parameter for regional groundwater flow analysis. This study suggests that hydraulic conductivities of rock mass are controlled by rock characteristics such as fractures, porosity and test conditions such as hydraulic gradient, water quality, water temperature and that there exists variations more than ten times in hydraulic conductivity by difference due to test conditions such as hydraulic gradient or due to rock type variations such as rock fractures, porosity. In addition this study demonstrated that confining pressure change caused by uplift and subsidence and change of hydraulic gradient under the long-term evolution of hydrogeological environment could possibly produce variations more than ten times of magnitude in hydraulic conductivity. It was also shown that the effect of water quality change on hydraulic conductivity was not negligible and that the replacement of fresh water and saline water caused by sea level change could induce 0.6 times in current hydraulic conductivities in case of Horonobe site. (author)

  17. Food supply reliance on groundwater

    Science.gov (United States)

    Dalin, Carole; Puma, Michael; Wada, Yoshihide; Kastner, Thomas

    2016-04-01

    Water resources, essential to sustain human life, livelihoods and ecosystems, are under increasing pressure from population growth, socio-economic development and global climate change. As the largest freshwater resource on Earth, groundwater is key for human development and food security. Yet, excessive abstraction of groundwater for irrigation, driven by an increasing demand for food in recent decades, is leading to fast exhaustion of groundwater reserves in major agricultural areas of the world. Some of the highest depletion rates are observed in Pakistan, India, California Central Valley and the North China Plain aquifers. In addition, the growing economy and population of several countries, such as India and China, makes prospects of future available water and food worrisome. In this context, it is becoming particularly challenging to sustainably feed the world population, without exhausting our water resources. Besides, food production and consumption across the globe have become increasingly interconnected, with many areas' agricultural production destined to remote consumers. In this globalisation era, trade is crucial to the world's food system. As a transfer of water-intensive goods, across regions with varying levels of water productivity, food trade can save significant volumes of water resources globally. This situation makes it essential to address the issue of groundwater overuse for global food supply, accounting for international food trade. To do so, we quantify the current, global use of non-renewable groundwater for major crops, accounting for various water productivity and trade flows. This will highlight areas requiring quickest attention, exposing major exporters and importers of non-renewable groundwater, and thus help explore solutions to improve the sustainability of global food supply.

  18. High gradient RF breakdown study

    International Nuclear Information System (INIS)

    Laurent, L.; Luhmann, N.C. Jr.; Scheitrum, G.; Hanna, S.; Pearson, C.; Phillips, R.

    1998-01-01

    Stanford Linear Accelerator Center and UC Davis have been investigating high gradient RF breakdown and its effects on pulse shortening in high energy microwave devices. RF breakdown is a critical issue in the development of high power microwave sources and next generation linear accelerators since it limits the output power of microwave sources and the accelerating gradient of linacs. The motivation of this research is to find methods to increase the breakdown threshold level in X-band structures by reducing dark current. Emphasis is focused on improved materials, surface finish, and cleanliness. The test platform for this research is a traveling wave resonant ring. A 30 MW klystron is employed to provide up to 300 MW of traveling wave power in the ring to trigger breakdown in the cavity. Five TM 01 cavities have previously been tested, each with a different combination of surface polish and/or coating. The onset of breakdown was extended up to 250 MV/m with a TiN surface finish, as compared to 210 MV/m for uncoated OFE copper. Although the TiN coating was helpful in depressing the field emission, the lowest dark current was obtained with a 1 microinch surface finish, single-point diamond-turned cavity

  19. NIF optics phase gradient specfication

    International Nuclear Information System (INIS)

    Williams, W.; Auerbach, J.; Hunt, J.; Lawson, L.; Manes, K.; Orth, C.; Sacks, R.; Trenholme, J.; Wegner, P.

    1997-01-01

    A root-mean-square (rms) phase gradient specification seems to allow a good connection between the NIP optics quality and focal spot requirements. Measurements on Beamlet optics individually, and as a chain, indicate they meet the assumptions necessary to use this specification, and that they have a typical rms phase gradient of ∼80 angstrom/cm. This may be sufficient for NIP to meet the proposed Stockpile Stewardship Management Program (SSMP) requirements of 80% of a high- power beam within a 200-250 micron diameter spot. Uncertainties include, especially, the scale length of the optics phase noise, the ability of the adaptive optic to correct against pump-induced distortions and optics noise, and the possibility of finding mitigation techniques against whole-beam self-focusing (e.g. a pre- correction optic). Further work is needed in these areas to better determine the NIF specifications. This memo is a written summary of a presentation on this topic given by W. Williams 24 April 1997 to NIP and LS ampersand T personnel

  20. Characterizing the Sensitivity of Groundwater Storage to Climate variation in the Indus Basin

    Science.gov (United States)

    Huang, L.; Sabo, J. L.

    2017-12-01

    Indus Basin represents an extensive groundwater aquifer facing the challenge of effective management of limited water resources. Groundwater storage is one of the most important variables of water balance, yet its sensitivity to climate change has rarely been explored. To better estimate present and future groundwater storage and its sensitivity to climate change in the Indus Basin, we analyzed groundwater recharge/discharge and their historical evolution in this basin. Several methods are applied to specify the aquifer system including: water level change and storativity estimates, gravity estimates (GRACE), flow model (MODFLOW), water budget analysis and extrapolation. In addition, all of the socioeconomic and engineering aspects are represented in the hydrological system through the change of temporal and spatial distributions of recharge and discharge (e.g., land use, crop structure, water allocation, etc.). Our results demonstrate that the direct impacts of climate change will result in unevenly distributed but increasing groundwater storage in the short term through groundwater recharge. In contrast, long term groundwater storage will decrease as a result of combined indirect and direct impacts of climate change (e.g. recharge/discharge and human activities). The sensitivity of groundwater storage to climate variation is characterized by topography, aquifer specifics and land use. Furthermore, by comparing possible outcomes of different human interventions scenarios, our study reveals human activities play an important role in affecting the sensitivity of groundwater storage to climate variation. Over all, this study presents the feasibility and value of using integrated hydrological methods to support sustainable water resource management under climate change.

  1. The spatial geochemical characteristics of groundwater and surface in the Tuul River basin, Ulaanbatar, Mongolia

    Science.gov (United States)

    Batdelger, Odsuren; Tsujimura, Maki; Zorigt, Byambasuren; Togtokh, Enkhjargal

    2017-04-01

    The capital city, Ulaanbaatar, is located along the Tuul River and its water supply totally dependent on the groundwater, which comes from the aquifer of the Tuul River. Due to the rapid growth of the population and the increasing human pressures in this basin, water quality has been deteriorating and has become a crucial issue for sustainable environmental and socio-economic development. Hydro-chemical and stable isotope tracing approaches were applied into the groundwater and surface water in order to study geochemical characteristics and groundwater and surface water interaction. The Tuul River water was mostly characterized by the Ca-HCO3 type, spatially variable and it changed into Ca-Na-HCO3 type in the downstream of the city after wastewater (WW) meets the river. Also, electrical conductivity (EC) values of Tuul River are increasing gradually with distance and it increased more than 2 times after WW meets the stream, therefore anthropogenic activities influence to the downstream of the river. The dominant hydro-chemical facies of groundwater were the Ca-HCO3 type, which represents 83% of the total analyzed samples, while Ca- HCO3-Cl-NO3, Na-HCO3, Ca-HCO3-SO4 each represent 4%, and Ca-mixed and Ca-Mg-HCO3 each represent 2% of the total samples. This suggests that groundwater chemistry is controlled by rock-water interaction and anthropogenic pollution. The floodplain groundwater chemical characteristics were similar to Tuul River water and showing lowest EC values. Groundwater far from floodplain showed higher EC (mean value of 498 μs/cm) values than river waters and floodplain groundwater. Also, different kinds of hydro-chemical facies were observed. The stable isotopic compositions revealed less evaporation effect on the groundwater and surface water, as well as an altitude effect in the river water. The similarity of stable isotopes and chemical characteristics of floodplain groundwater and river water suggests that alluvial groundwater is recharged by

  2. Groundwater vulnerability assessment: from overlay methods to statistical methods in the Lombardy Plain area

    Directory of Open Access Journals (Sweden)

    Stefania Stevenazzi

    2017-06-01

    Full Text Available Groundwater is among the most important freshwater resources. Worldwide, aquifers are experiencing an increasing threat of pollution from urbanization, industrial development, agricultural activities and mining enterprise. Thus, practical actions, strategies and solutions to protect groundwater from these anthropogenic sources are widely required. The most efficient tool, which helps supporting land use planning, while protecting groundwater from contamination, is represented by groundwater vulnerability assessment. Over the years, several methods assessing groundwater vulnerability have been developed: overlay and index methods, statistical and process-based methods. All methods are means to synthesize complex hydrogeological information into a unique document, which is a groundwater vulnerability map, useable by planners, decision and policy makers, geoscientists and the public. Although it is not possible to identify an approach which could be the best one for all situations, the final product should always be scientific defensible, meaningful and reliable. Nevertheless, various methods may produce very different results at any given site. Thus, reasons for similarities and differences need to be deeply investigated. This study demonstrates the reliability and flexibility of a spatial statistical method to assess groundwater vulnerability to contamination at a regional scale. The Lombardy Plain case study is particularly interesting for its long history of groundwater monitoring (quality and quantity, availability of hydrogeological data, and combined presence of various anthropogenic sources of contamination. Recent updates of the regional water protection plan have raised the necessity of realizing more flexible, reliable and accurate groundwater vulnerability maps. A comparison of groundwater vulnerability maps obtained through different approaches and developed in a time span of several years has demonstrated the relevance of the

  3. Quality-assurance plan for groundwater activities, U.S. Geological Survey, Washington Water Science Center

    Science.gov (United States)

    Kozar, Mark D.; Kahle, Sue C.

    2013-01-01

    This report documents the standard procedures, policies, and field methods used by the U.S. Geological Survey’s (USGS) Washington Water Science Center staff for activities related to the collection, processing, analysis, storage, and publication of groundwater data. This groundwater quality-assurance plan changes through time to accommodate new methods and requirements developed by the Washington Water Science Center and the USGS Office of Groundwater. The plan is based largely on requirements and guidelines provided by the USGS Office of Groundwater, or the USGS Water Mission Area. Regular updates to this plan represent an integral part of the quality-assurance process. Because numerous policy memoranda have been issued by the Office of Groundwater since the previous groundwater quality assurance plan was written, this report is a substantial revision of the previous report, supplants it, and contains significant additional policies not covered in the previous report. This updated plan includes information related to the organization and responsibilities of USGS Washington Water Science Center staff, training, safety, project proposal development, project review procedures, data collection activities, data processing activities, report review procedures, and archiving of field data and interpretative information pertaining to groundwater flow models, borehole aquifer tests, and aquifer tests. Important updates from the previous groundwater quality assurance plan include: (1) procedures for documenting and archiving of groundwater flow models; (2) revisions to procedures and policies for the creation of sites in the Groundwater Site Inventory database; (3) adoption of new water-level forms to be used within the USGS Washington Water Science Center; (4) procedures for future creation of borehole geophysics, surface geophysics, and aquifer-test archives; and (5) use of the USGS Multi Optional Network Key Entry System software for entry of routine water-level data

  4. Groundwater quality in the Sierra Nevada, California

    Science.gov (United States)

    Fram, Miranda S.; Belitz, Kenneth

    2014-01-01

    Groundwater provides more than 40 percent of California’s drinking water. To protect this vital resource, the State of California created the Groundwater Ambient Monitoring and Assessment (GAMA) Program. The Priority Basin Project (PBP) of the GAMA Program provides a comprehensive assessment of the State’s groundwater quality and increases public access to groundwater-quality information. The Sierra Nevada Regional study unit constitutes one of the study units being evaluated.

  5. Groundwater quality in the Klamath Mountains, California

    Science.gov (United States)

    Bennett, George L.; Fram, Miranda S.

    2014-01-01

    Groundwater provides more than 40 percent of California’s drinking water. To protect this vital resource, the State of California created the Groundwater Ambient Monitoring and Assessment (GAMA) Program. The Priority Basin Project of the GAMA Program provides a comprehensive assessment of the State’s groundwater quality and increases public access to groundwater-quality information. The Klamath Mountains constitute one of the study units being evaluated.

  6. Complexed iron removal from groundwater

    Energy Technology Data Exchange (ETDEWEB)

    Munter, R.; Ojaste, H.; Sutt, J. [Tallinn Technical University, Tallinn (Estonia). Dept. of Environmental & Chemical Technology

    2005-07-01

    The paper demonstrates an intensive work carried out and results obtained on the pilot plant of the City of Kogalym Water Treatment Station (Tjumen, Siberia, Russian Federation) to elaborate on a contemporary nonreagent treatment technology for the local iron-rich groundwater. Several filter materials (Birm, Pyrolox, hydroanthracite, Everzit, granulated activated carbon) and chemical oxidants (ozone, chlorine, hydrogen peroxide, oxygen, and potassium permanganate) were tested to solve the problem with complexed iron removal from groundwater. The final elaborated technology consists of raw water intensive aeration in the gas-degas treatment unit followed by sequential filtration through hydroanthracite and the special anthracite Everzit.

  7. Groundwater and Terrestrial Water Storage

    Science.gov (United States)

    Rodell, Matthew; Chambers, Don P.; Famiglietti, James S.

    2014-01-01

    Terrestrial water storage (TWS) comprises groundwater, soil moisture, surface water, snow,and ice. Groundwater typically varies more slowly than the other TWS components because itis not in direct contact with the atmosphere, but often it has a larger range of variability onmultiannual timescales (Rodell and Famiglietti, 2001; Alley et al., 2002). In situ groundwaterdata are only archived and made available by a few countries. However, monthly TWSvariations observed by the Gravity Recovery and Climate Experiment (GRACE; Tapley et al.,2004) satellite mission, which launched in 2002, are a reasonable proxy for unconfinedgroundwater at climatic scales.

  8. Features of groundwater pollution and its relation to overexploitation of groundwater in Shijiazhuang city

    International Nuclear Information System (INIS)

    Guo Yonghai; Wang Zhiming; Liu Shufen; Li Ping

    2005-01-01

    The groundwater pollution in Shijiazhuang city is characterized by an excess of some components and parameters over permitted values. The main pollutants are originated from the city sewage which is quite typical for groundwater pollution in many cities of China. On the basis of agonizingly features of groundwater pollution, the relationship between the groundwater pollution and the groundwater overexploitation is discussed in this paper, and the mechanism of intensifying the pollution by overexploitation has been revealed. Finally, it is proposed that the overexploitation of groundwater is an important inducing factor leading to the groundwater pollution in cities. (authors)

  9. Hydrogeologic framework and selected components of the groundwater budget for the upper Umatilla River Basin, Oregon

    Science.gov (United States)

    Herrera, Nora B.; Ely, Kate; Mehta, Smita; Stonewall, Adam J.; Risley, John C.; Hinkle, Stephen R.; Conlon, Terrence D.

    2017-05-31

    Umatilla River Basin during 1951–2010 is about 9.6 inches per year (in/yr). Annual recharge from precipitation for water year 2010 ranged from 3 in. in the lowland area to about 30 in. in the Blue Mountains. Using Kahle and others (2011) data and methods from the Columbia Plateau regional model, average annual recharge from irrigation is estimated to be about 2.2 in/yr for the 13 square miles of irrigated land in the upper Umatilla River Basin.Groundwater discharges to streams throughout the year and is a large component of annual streamflow in the upper Umatilla River Basin. Upward vertical hydraulic gradients near the Umatilla River indicate the potential for groundwater discharge. Groundwater discharge to the Umatilla River generally occurs in the upper part of the basin, upstream from the main stem.Groundwater development in the upper Umatilla River Basin began sometime after 1950 (Davies-Smith and others, 1988; Gonthier and Bolke, 1991). By water year 2010, groundwater use in the upper Umatilla River Basin was approximately 11,214 acre-feet (acre-ft). Total groundwater withdrawals for the study area were estimated at 7,575 acre-ft for irrigation, 3,173 acre-ft for municipal use, and 466 acre-ft for domestic use.Total groundwater flow into or from the study area depends locally on geology and hydraulic head distribution. Estimates of subsurface flow were calculated using the U.S. Geological Survey Columbia Plateau regional groundwater flow model. Net flux values range from 25,000 to 27,700 acre-ft per year and indicate that groundwater is moving out of the upper Umatilla River Basin into the lower Umatilla River Basin.Water level changes depend on storage changes within an aquifer, and storage changes depend on the storage properties of the aquifer, as well as recharge to or discharge from the aquifer. Groundwater level data in the upper Umatilla River Basin are mostly available from wells in Columbia River basalt units, which indicate areas of long-term water level

  10. Representative process sampling - in practice

    DEFF Research Database (Denmark)

    Esbensen, Kim; Friis-Pedersen, Hans Henrik; Julius, Lars Petersen

    2007-01-01

    Didactic data sets representing a range of real-world processes are used to illustrate "how to do" representative process sampling and process characterisation. The selected process data lead to diverse variogram expressions with different systematics (no range vs. important ranges; trends and....../or periodicity; different nugget effects and process variations ranging from less than one lag to full variogram lag). Variogram data analysis leads to a fundamental decomposition into 0-D sampling vs. 1-D process variances, based on the three principal variogram parameters: range, sill and nugget effect...

  11. State space modeling of groundwater fluctuations

    NARCIS (Netherlands)

    Berendrecht, W.L.

    2004-01-01

    Groundwater plays an important role in both urban and rural areas. It is therefore essential to monitor groundwater fluctuations. However, data that becomes available need to be analyzed further in order to extract specific information on the groundwater system. Until recently, simple linear time

  12. Quantification of Seepage in Groundwater Dependent Wetlands

    DEFF Research Database (Denmark)

    Johansen, Ole; Beven, Keith; Jensen, Jacob Birk

    2018-01-01

    Restoration and management of groundwater dependent wetlands require tools for quantifying the groundwater seepage process. A method for determining point estimates of the groundwater seepage based on water level observations is tested. The study is based on field data from a Danish rich fen...

  13. Simulation–optimization model for groundwater contamination ...

    Indian Academy of Sciences (India)

    used techniques for groundwater remediation in which the contaminated groundwater is pumped ... ing the affected groundwater aquifer down to some drinking water standard. Several .... For simplicity, rectangular support domain is used in this study. Figure 1 ..... For PAT remediation system, decision variables include the.

  14. Mapping groundwater quality in the Netherlands

    NARCIS (Netherlands)

    Pebesma, Edzer Jan

    1996-01-01

    Groundwater quality is the suitability of groundwater for a certain purpose (e.g. for human consumption), and is mostly determined by its chemical composition. Pollution from agricultural and industrial origin threatens the groundwater quality in the Netherlands. Locally, this pollution is

  15. A proposed groundwater management framework for municipalities ...

    African Journals Online (AJOL)

    Groundwater is not being perceived as an important water resource and therefore has been given limited attention in South. Africa. This is reflected in general ... Research Commission (WRC) has commissioned a project to develop a Groundwater Management Framework that incorpo- rates all aspects of groundwater ...

  16. NORTH CAROLINA GROUNDWATER RECHARGE RATES 1994

    Science.gov (United States)

    North Carolina Groundwater Recharge Rates, from Heath, R.C., 1994, Ground-water recharge in North Carolina: North Carolina State University, as prepared for the NC Department of Environment, Health and Natural Resources (NC DEHNR) Division of Enviromental Management Groundwater S...

  17. Design Of Bioremediation Systems For Groundwater (Aerobic and Anaerobic Plus Representative Case Studies)

    Science.gov (United States)

    The attached presentation discusses the fundamentals of bioremediation in the subsurface. The basics of aerobic, cometabolic, and anaerobic bioremediation are presented. Case studies from the Delaware Sand & Gravel Superfund Site, Dover Cometabolic Research Project and the SABR...

  18. Geophysical logging of bedrock wells for geothermal gradient characterization in New Hampshire, 2013

    Science.gov (United States)

    Degnan, James R.; Barker, Gregory; Olson, Neil; Wilder, Leland

    2014-01-01

    The U.S. Geological Survey, in cooperation with the New Hampshire Geological Survey, measured the fluid temperature of groundwater and other geophysical properties in 10 bedrock wells in the State of New Hampshire in order to characterize geothermal gradients in bedrock. The wells selected for the study were deep (five ranging from 375 to 900 feet and five deeper than 900 feet) and 6 had low water yields, which correspond to low groundwater flow from fractures. This combination of depth and low water yield reduced the potential for flow-induced temperature changes that would mask the natural geothermal gradient in the bedrock. All the wells included in this study are privately owned, and permission to use the wells was obtained from landowners before geophysical logs were acquired for this study. National Institute of Standards and Technology thermistor readings were used to adjust the factory calibrated geophysical log data. A geometric correction to the gradient measurements was also necessary due to borehole deviation from vertical.

  19. NEON, Establishing a Standardized Network for Groundwater Observations

    Science.gov (United States)

    Fitzgerald, M.; Schroeter, N.; Goodman, K. J.; Roehm, C. L.

    2013-12-01

    The National Ecological Observatory Network (NEON) is establishing a standardized set of data collection systems comprised of in-situ sensors and observational sampling to obtain data fundamental to the analysis of environmental change at a continental scale. NEON will be collecting aquatic, terrestrial, and atmospheric data using Observatory-wide standardized designs and methods via a systems engineering approach. This approach ensures a wealth of high quality data, data algorithms, and models that will be freely accessible to all communities such as academic researchers, policy makers, and the general public. The project is established to provide 30 years of data which will enable prediction and forecasting of drivers and responses of ecological change at scales ranging from localized responses through regional gradients and up to the continental scale. The Observatory is a distributed system of sites spread across the United States, including Alaska, Hawaii, and Puerto Rico, which is subdivided into 20 statistically unique domains, based on a set of 18 ecologically important parameters. Each domain contains at least one core aquatic and terrestrial site which are located in unmanaged lands, and up to 2 additional sites selected to study domain specific questions such as nitrogen deposition gradients and responses of land use change activities on the ecosystem. Here, we present the development of NEON's groundwater observation well network design and the timing strategy for sampling groundwater chemistry. Shallow well networks, up to 100 feet in depth, will be installed at NEON aquatic sites and will allow for observation of localized ecohydrologic site conditions, by providing basic spatio-temporal near-real time data on groundwater parameters (level, temperature, conductivity) collected from in situ high-resolution instrumentation positioned in each well; and biannual sampling of geochemical and nutrient (N and P) concentrations in a subset of wells for each

  20. Marc Treib: Representing Landscape Architecture

    DEFF Research Database (Denmark)

    Braae, Ellen Marie

    2008-01-01

    The editor of Representing Landscape Architecture, Marc Treib, argues that there is good reason to evaluate the standard practices of representation that landscape architects have been using for so long. In the rush to the promised land of computer design these practices are now in danger of being...

  1. Does representative wind information exist?

    NARCIS (Netherlands)

    Wieringa, J.

    1996-01-01

    Representativity requirements are discussed for various wind data users. It is shown that most applications can be dealt with by using data from wind stations when these are made to conform with WMO specifications. Methods to achieve this WMO normalization are reviewed, giving minimum specifications

  2. OAS :: Member States : Permanent Representatives

    Science.gov (United States)

    Rights Actions against Corruption C Children Civil Registry Civil Society Contact Us Culture Cyber Barbados Belize Bolivia Brazil Canada Chile Colombia Costa Rica Cuba 1 Dominica (Commonwealth of) Dominican Gutierez Ambassador, Permanent Representative of Belize Diego Pary Rodríguez Bolivia Diego Pary Rodríguez

  3. Judgments of and by Representativeness

    Science.gov (United States)

    1981-05-15

    p. 4i). This hy- pothesis was studied in several contexts, including intuitive statisti- cal judgments and the prediction of professional choice (Kahneman... professional choice . Here, X is representative of M either because it is frequently associated with M (e.g., high fever commonly accompanies pneumonia

  4. WIPP facility representative program plan

    International Nuclear Information System (INIS)

    1994-01-01

    This plan describes the Department of Energy (DOE), Carlsbad Area Office (CAO) facility representative (FR) program at the Waste Isolation Pilot Plant (WIPP). It provides the following information: (1) FR and support organization authorities and responsibilities; (2) FR program requirements; and (3) FR training and qualification requirements

  5. Strength gradient enhances fatigue resistance of steels

    Science.gov (United States)

    Ma, Zhiwei; Liu, Jiabin; Wang, Gang; Wang, Hongtao; Wei, Yujie; Gao, Huajian

    2016-02-01

    Steels are heavily used in infrastructure and the transportation industry, and enhancing their fatigue resistance is a major challenge in materials engineering. In this study, by introducing a gradient microstructure into 304 austenitic steel, which is one of the most widely used types of stainless steel, we show that a strength gradient substantially enhances the fatigue life of the material. Pre-notched samples with negative strength gradients in front of the notch’s tip endure many more fatigue cycles than do samples with positive strength gradients during the crack initiation stage, and samples with either type of gradient perform better than do gradient-free samples with the same average yield strength. However, as a crack grows, samples with positive strength gradients exhibit better resistance to fatigue crack propagation than do samples with negative gradients or no gradient. This study demonstrates a simple and promising strategy for using gradient structures to enhance the fatigue resistance of materials and complements related studies of strength and ductility.

  6. Adsorptive Iron Removal from Groundwater

    NARCIS (Netherlands)

    Sharma, S.K.

    2001-01-01

    Iron is commonly present in groundwater worldwide. The presence of iron in drinking water is not harmful to human health, however it is undesirable because of the associated aesthetic and operational problems, namely: bad taste, colour, stains on laundry and plumbing fixtures, and aftergrowth in the

  7. Adsorptive iron removal from groundwater

    NARCIS (Netherlands)

    Sharma, S.K.

    2001-01-01

    Iron is commonly present in groundwater worldwide. The presence of iron in the water supply is not harmful to human health, however it is undesirable. Bad taste, discoloration, staining, deposition in the distribution system leading to aftergrowth, and incidences of high turbidity are some

  8. COVARIANCE CORRECTION FOR ESTIMATING GROUNDWATER ...

    African Journals Online (AJOL)

    2015-01-15

    Jan 15, 2015 ... between zero and one, depending on location of the observation ..... [1] Alley W.M., Reilly T.E., Franke O.L., Sustainability of ground-water resources, U.S. ... Data assimilation: the ensemble Kalman filter, Springer, New York, ...

  9. Groundwater regulation and integrated planning

    Science.gov (United States)

    Quevauviller, Philippe; Batelaan, Okke; Hunt, Randall J.

    2016-01-01

    The complex nature of groundwater and the diversity of uses and environmental interactions call for emerging groundwater problems to be addressed through integrated management and planning approaches. Planning requires different levels of integration dealing with: the hydrologic cycle (the physical process) including the temporal dimension; river basins and aquifers (spatial integration); socioeconomic considerations at regional, national and international levels; and scientific knowledge. The great natural variation in groundwater conditions obviously affects planning needs and options as well as perceptions from highly localised to regionally-based approaches. The scale at which planning is done therefore needs to be carefully evaluated against available policy choices and options in each particular setting. A solid planning approach is based on River Basin Management Planning (RBMP), which covers: (1) objectives that management planning are designed to address; (2) the way various types of measures fit into the overall management planning; and (3) the criteria against which the success or failure of specific strategies or interventions can be evaluated (e.g. compliance with environmental quality standards). A management planning framework is to be conceived as a “living” or iterated document that can be updated, refined and if necessary changed as information and experience are gained. This chapter discusses these aspects, providing an insight into European Union (EU), United States and Australia groundwater planning practices.

  10. HYDROGEOPHYSICAL EVALUATION OF THE GROUNDWATER ...

    African Journals Online (AJOL)

    Timothy Ademakinwa

    Vertical Electrical Soundings (VES) and hydrogeological data were used to delineate the subsurface sequence and map the aquifer units with a view to evaluating the groundwater prospect of the central part of Ogun State,. Southwestern Nigeria. Thirty Schlumberger VES with maximum current electrode spacing (AB) of ...

  11. Hydrogeological Investigation and Groundwater Potential ...

    African Journals Online (AJOL)

    The paper assesses groundwater quality and productivity in Haromaya watershed, eastern. Ethiopia. ... zones, quantity and quality of plant and animal life (Tamire H., 1981). Steep to very ... Present research work was proposed to conduct hydrogeological investigation and assess ...... Water Balance of Haromaya basin,.

  12. 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

  13. Effects of Submarine Groundwater Discharge (SGD) on the Growth of the Lobe Coral Porites lobata in Maunalua Bay, Hawaii.

    Science.gov (United States)

    Lubarsky, K.

    2016-02-01

    Submarine groundwater discharge (SGD) constitutes a large percentage of the freshwater inputs onto coastal coral reefs on high islands such as the Hawaiian Islands, although the impact of SGD on coral reef health is currently understudied. In Maunalua Bay, on Oahu, Hawaii, SGD is discharged onto shallow reef flats from discrete seeps, creating natural gradients of water chemistry across the reef flat. We used this system to investigate rates of growth of the lobe coral Porites lobata across a gradient of SGD influence at two study sites within the bay, and to characterize the variation in water chemistry gradient over space and time due to SGD. SGD input at these sites is tidally modulated, and the groundwater itself is brackish and extremely nutrient-rich (mean=190 μM NO3- at the Black Point study site, mean=40 μM NO3- at Wailupe Beach Park), with distinct carbonate signatures at both study sites. Coral nubbins were placed across the gradient for 6 months, and growth was measured using three metrics: surface area (photo analysis), buoyant weight, and linear extension. Various chemical parameters, including pH, salinity, total alkalinity, nutrients, and chlorphyll were sampled at the same locations across the gradient over 24 hour periods in the spring and fall in order to capture spatial and temporal variation in water chemistry due to the SGD plume. Spatial patterns and temporal variation in water chemistry were correlated with the observed spatial patterns in coral growth across the SGD gradient.

  14. Radionuclide inventories for the F- and H-area seepage basin groundwater plumes

    Energy Technology Data Exchange (ETDEWEB)

    Hiergesell, Robert A [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Kubilius, Walter P. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2016-05-01

    Within the General Separations Areas (GSA) at the Savannah River Site (SRS), significant inventories of radionuclides exist within two major groundwater contamination plumes that are emanating from the F- and H-Area seepage basins. These radionuclides are moving slowly with groundwater migration, albeit more slowly due to interaction with the soil and aquifer matrix material. The purpose of this investigation is to quantify the activity of radionuclides associated with the pore water component of the groundwater plumes. The scope of this effort included evaluation of all groundwater sample analyses obtained from the wells that have been established by the Environmental Compliance & Area Completion Projects (EC&ACP) Department at SRS to monitor groundwater contamination emanating from the F- and H-Area Seepage Basins. Using this data, generalized groundwater plume maps for the radionuclides that occur in elevated concentrations (Am-241, Cm-243/244, Cs-137, I-129, Ni-63, Ra-226/228, Sr-90, Tc-99, U-233/234, U-235 and U-238) were generated and utilized to calculate both the volume of contaminated groundwater and the representative concentration of each radionuclide associated with different plume concentration zones.

  15. Archaeal Diversity and CO2 Fixers in Carbonate-/Siliciclastic-Rock Groundwater Ecosystems

    Directory of Open Access Journals (Sweden)

    Cassandre Sara Lazar

    2017-01-01

    Full Text Available Groundwater environments provide habitats for diverse microbial communities, and although Archaea usually represent a minor fraction of communities, they are involved in key biogeochemical cycles. We analysed the archaeal diversity within a mixed carbonate-rock/siliciclastic-rock aquifer system, vertically from surface soils to subsurface groundwater including aquifer and aquitard rocks. Archaeal diversity was also characterized along a monitoring well transect that spanned surface land uses from forest/woodland to grassland and cropland. Sequencing of 16S rRNA genes showed that only a few surface soil-inhabiting Archaea were present in the groundwater suggesting a restricted input from the surface. Dominant groups in the groundwater belonged to the marine group I (MG-I Thaumarchaeota and the Woesearchaeota. Most of the groups detected in the aquitard and aquifer rock samples belonged to either cultured or predicted lithoautotrophs (e.g., Thaumarchaeota or Hadesarchaea. Furthermore, to target autotrophs, a series of 13CO2 stable isotope-probing experiments were conducted using filter pieces obtained after filtration of 10,000 L of groundwater to concentrate cells. These incubations identified the SAGMCG Thaumarchaeota and Bathyarchaeota as groundwater autotrophs. Overall, the results suggest that the majority of Archaea on rocks are fixing CO2, while archaeal autotrophy seems to be limited in the groundwater.

  16. Anthropization of groundwater resources in the Mediterranean region: processes and challenges

    Science.gov (United States)

    Leduc, Christian; Pulido-Bosch, Antonio; Remini, Boualem

    2017-09-01

    A comprehensive overview is provided of processes and challenges related to Mediterranean groundwater resources and associated changes in recent decades. While most studies are focused thematically and/or geographically, this paper addresses different stages of groundwater exploitation in the region and their consequences. Examples emphasize the complex interactions between the physical and social dimensions of uses and evolution of groundwater. In natural conditions, Mediterranean groundwater resources represent a wide range of hydrogeological contexts, recharge conditions and rates of exploitation. They have been actively exploited for millennia but their pseudo-natural regimes have been considerably modified in the last 50 years, especially to satisfy agricultural demand (80% of total water consumption in North Africa), as well as for tourism and coastal cities. Climate variability affects groundwater dynamics but the various forms of anthropization are more important drivers of hydrological change, including changes in land use and vegetation, hydraulic works, and intense pumpings. These changes affect both the quantity and quality of groundwater at different scales, and modify the nature of hydrogeological processes, their location, timing, and intensity. The frequent cases of drastic overexploitation illustrate the fragility of Mediterranean groundwater resources and the limits of present forms of management. There is no easy way to maintain or recover sustainability, which is often threatened by short-term interests. To achieve this goal, a significant improvement in hydrogeological knowledge and closer collaboration between the various disciplines of water sciences are indispensable.

  17. Results of RCRA groundwater quality assessment at the 216-B-3 Pond Facility

    International Nuclear Information System (INIS)

    Barnett, D.B.; Teel, S.S.

    1997-06-01

    This document describes a groundwater quality assessment of the 216-B-3 pond system, a Resources Conservation and Recovery act of 1976 (RCRA) waste facility. In 1990, sampling and chemical analysis of groundwater underlying the facility indicated that the contamination indicator parameters, total organic halogens (TOX), and total organic carbon (TOC) had exceeded established limits in two wells. This discovery placed the facility into RCRA groundwater assessment status and subsequently led to a more detailed hydrochemical analysis of groundwater underlying the facility. Comprehensive chemical analyses of groundwater samples from 1994 through 1996 revealed one compound, tris (2-chloroethyl) phosphate (TRIS2CH), that may have contributed to elevated TOX concentrations. No compound was identified as a contributor to TOC. Detailed evaluations of TOX, TOC, and TRIS2CH and comparison of occurrences of these parameters led to conclusions that (1) with few exceptions, these constituents occur at low concentrations below or near limits of quantitation; (2) it is problematic whether the low concentrations of TRIS2CH represent a contaminant originating from the facility or if it is a product of well construction; and (3) given the low and diminishing concentration of TOX, TOC, and TRIS2CH, no further investigation into the occurrent of these constituents is justified. Continued groundwater monitoring should include an immediate recalculation of background critical means of upgradient/downgradient comparisons and a return to seminannual groundwater monitoring under a RCRA indicator parameter evaluation program

  18. Validation Analysis of the Shoal Groundwater Flow and Transport Model

    Energy Technology Data Exchange (ETDEWEB)

    A. Hassan; J. Chapman

    2008-11-01

    groundwater withdrawal activities in the area. The conceptual and numerical models were developed based upon regional hydrogeologic investigations conducted in the 1960s, site characterization investigations (including ten wells and various geophysical and geologic studies) at Shoal itself prior to and immediately after the test, and two site characterization campaigns in the 1990s for environmental restoration purposes (including eight wells and a year-long tracer test). The new wells are denoted MV-1, MV-2, and MV-3, and are located to the northnortheast of the nuclear test. The groundwater model was generally lacking data in the north-northeastern area; only HC-1 and the abandoned PM-2 wells existed in this area. The wells provide data on fracture orientation and frequency, water levels, hydraulic conductivity, and water chemistry for comparison with the groundwater model. A total of 12 real-number validation targets were available for the validation analysis, including five values of hydraulic head, three hydraulic conductivity measurements, three hydraulic gradient values, and one angle value for the lateral gradient in radians. In addition, the fracture dip and orientation data provide comparisons to the distributions used in the model and radiochemistry is available for comparison to model output. Goodness-of-fit analysis indicates that some of the model realizations correspond well with the newly acquired conductivity, head, and gradient data, while others do not. Other tests indicated that additional model realizations may be needed to test if the model input distributions need refinement to improve model performance. This approach (generating additional realizations) was not followed because it was realized that there was a temporal component to the data disconnect: the new head measurements are on the high side of the model distributions, but the heads at the original calibration locations themselves have also increased over time. This indicates that the steady

  19. Tracing submarine groundwater discharge in the NE Gulf of Mexico by 222Rn

    International Nuclear Information System (INIS)

    Young, J.E.; B