Grass buffers for playas in agricultural landscapes: A literature synthesis

Science.gov (United States)

Melcher, Cynthia P.; Skagen, Susan K.

2005-01-01

We summarize current knowledge about grass buffers for protecting small, isolated wetlands in agricultural contexts, including information relevant to protecting playas from runoff containing sediments, nutrients, pesticides, and other contaminants, and information on how buffers may affect densities and productivity of grassland birds. Land-uses surrounding the approximately 60,000 playas within the Playa Lakes Region (PLR), including intensive agriculture, feedlots, and oil extraction, can contribute to severe degradation of playas. Farming and grazing can lead to significant sedimentation in nearby playas, eliminating their ability to hold water, support the region’s biodiversity, or adequately recharge aquifers. Contaminants further degrade habitats and threaten the water quality of underlying aquifers, including the Ogallala Aquifer.

Characterizing fate and transport properties in karst aquifers under different hydrologic conditions

Science.gov (United States)

Rodriguez, E.; Padilla, I. Y.

2017-12-01

Karst landscapes contain very productive aquifers. The hydraulic and hydrogeological characteristics of karst aquifers make these systems capable of storing and transporting large amount of water, but also highly vulnerable to contamination. Their extremely heterogeneous nature prevents accurate prediction in contaminant fate and transport. Even more challenging is to understand the impact of hydrologic conditions changes on fate and transport processes. This studies aims at characterizing fate and transport processes in the karst groundwater system of northern Puerto Rico under different hydrologic conditions. The study involves injecting rhodamine and uranine dyes into a sinkhole, and monitoring concentrations at a spring. Results show incomplete recovery of tracers, but breaking curves can be used to estimate advective, dispersive and mass transfer characteristic of the karst system. Preliminary results suggest significant differences in fate and transport characteristics under different hydrologic conditions.

Differentiated spring behavior under changing hydrological conditions in an alpine karst aquifer

Science.gov (United States)

Filippini, Maria; Squarzoni, Gabriela; De Waele, Jo; Fiorucci, Adriano; Vigna, Bartolomeo; Grillo, Barbara; Riva, Alberto; Rossetti, Stefano; Zini, Luca; Casagrande, Giacomo; Stumpp, Christine; Gargini, Alessandro

2018-01-01

Limestone massifs with a high density of dolines form important karst aquifers in most of the Alps, often with groundwater circulating through deep karst conduits and water coming out of closely spaced springs with flow rates of over some cubic meters per second. Although several hydrogeological studies and tracing experiments were carried out in many of these carbonate mountains in the past, the hydrogeology of most of these karst aquifers is still poorly known. Geological, hydrodynamic and hydrochemical investigations have been carried out in one of the most representative of these areas (Cansiglio-Monte Cavallo, NE Italy) since spring 2015, in order to enhance the knowledge on this important type of aquifer system. Additionally, a cave-to-spring multitracer test was carried out in late spring 2016 by using three different fluorescent tracers. This hydrogeological study allowed: 1) gathering new detailed information on the geological and tectonic structure of such alpine karst plateau; 2) defining discharge rates of the three main springs (Gorgazzo, Santissima, and Molinetto) by constructing rating curves; 3) understanding the discharging behavior of the system with respect to different recharge conditions; 4) better defining the recharge areas of the three springs. The three nearby springs (the spring front stretches over 5 km), that drain the investigated karst aquifer system, show different behaviors with respect to changing discharge conditions, demonstrating this aquifer to be divided in partially independent drainage systems under low-flow conditions, when their chemistry is clearly differentiated. Under high-flow conditions, waters discharging at all springs show more similar geochemical characteristics. The combination of geochemistry, hydrodynamic monitoring and dye tracing tests has shown that the three springs have different recharge areas. The study points out that even closely spaced karst springs, that apparently drain the same karst mountain, can

Regional Management of an Aquifer for Mining Under Fuzzy Environmental Objectives

Science.gov (United States)

BogáRdi, IstváN.; BáRdossy, AndráS.; Duckstein, Lucien

1983-12-01

A methodology is developed for the dynamic multiobjective management of a multipurpose regional aquifer. In a case study of bauxite mining in Western Hungary, ore deposits are often under the piezometric level of a karstic aquifer, while this same aquifer also provides recharge flows for thermal springs. N + 1 objectives are to be minimized, the first one being total discounted cost of control by dewatering or grouting; the other N objectives consist of the flow of thermal springs at N control points. However, there is no agreement among experts as to a set of numerical values that would constitute a "sound environment"; for this reason a fuzzy set analysis is used, and the N environmental objectives are combined into a single fuzzy membership function. The constraints include ore availability, various capacities, and the state transition function that describes the behavior of both piezometric head and underground flow. The model is linearized and solved as a biobjective dynamic program by using multiobjective compromise programming. A numerical example with N = 2 appears to lead to realistic control policies. Extension of the model to the nonlinear case is discussed.

Potentiometric surfaces, summer 2013 and winter 2015, and select hydrographs for the Southern High Plains aquifer, Cannon Air Force Base, Curry County, New Mexico

Science.gov (United States)

Collison, Jake

2016-04-07

Cannon Air Force Base (Cannon AFB) is located in the High Plains physiographic region of east-central New Mexico, about 5 miles west of Clovis, New Mexico. The area surrounding Cannon AFB is primarily used for agriculture, including irrigated cropland and dairies. The Southern High Plains aquifer is the principal source of water for Cannon AFB, for the nearby town of Clovis, and for local agriculture and dairies. The Southern High Plains aquifer in the vicinity of Cannon AFB consists of three subsurface geological formations: the Chinle Formation of Triassic age, the Ogallala Formation of Tertiary age, and the Blackwater Draw Formation of Quaternary age. The Ogallala Formation is the main water-yielding formation of the Southern High Plains aquifer. Groundwater-supplied, center-pivot irrigation dominates pumping from the Southern High Plains aquifer in the area surrounding Cannon AFB, where the irrigation season typically extends from early March through October. The U.S. Geological Survey has been monitoring groundwater levels in the vicinity of Cannon AFB since 1954 and has developed general potentiometric-surface maps that show groundwater flow from northwest to southeast in the study area. While previous potentiometric-surface maps show the general direction of groundwater flow, a denser well network is needed to show details of groundwater flow at a local scale. Groundwater levels were measured in 93 wells during summer 2013 and 100 wells during winter 2015.The summer and winter potentiometric-surface maps display the presence of what is interpreted to be a groundwater trough trending from the northwest to the southeast through the study area. This groundwater trough may be the hydraulic expression of a Tertiary-age paleochannel. Groundwater north of the trough flows in a southerly direction into the trough, and groundwater south of the trough flows in an easterly direction into the trough.During the 18-month period between summer 2013 and winter 2015, changes

Preliminary analysis of some waters from the confined aquifers underlying the Hanford site

International Nuclear Information System (INIS)

Deju, R.A.

1978-09-01

This report presents results of analyses available at this time from waters from some wells sampled in or near the Hanford Site. The analyses of these wells were done for various purposes and are consolidated to help define the nature of the waters found within the Columbia Plateau basaltic sequence. Results of the analyses show the waters from the unconfined aquifers underlying the Hanford Site are characterized by a high calcium--magnesium content. These waters can be described as calcium--magnesium--bicarbonate-type. Waters from deeper basaltic confined aquifers are primarily of the sodium bicarbonate type. Two waters sampled from the Grande Ronde Formation from Rattlesnake Hills Exploratory Well Number 1 are slightly different and can be described as sodium--calcium--bicarbonate--sulfate--chloride-type. Age-dating results for these water samples lead to the conclusions that waters from the confined aquifers were entrapped 15,000 to 23,000 years ago

Inference of Stream Network Fragmentation Patterns from Ground Water - Surface Water Interactions on the High Plains Aquifer

Science.gov (United States)

Chandler, D. G.; Yang, X.; Steward, D. R.; Gido, K.

2007-12-01

Stream networks in the Great Plains integrate fluxes from precipitation as surface runoff in discrete events and groundwater as base flow. Changes in land cover and agronomic practices and development of ground water resources to support irrigated agriculture have resulted in profound changes in the occurrence and magnitude of stream flows, especially near the Ogallala aquifer, where precipitation is low. These changes have demonstrably altered the aquatic habitat of western Kansas, with documented changes in fish populations, riparian communities and groundwater quality due to stream transmission losses. Forecasting future changes in aquatic and riparian ecology and groundwater quality requires a large scale spatially explicit model of groundwater- surface water interaction. In this study, we combine historical data on land use, stream flow, production well development and groundwater level observations with groundwater elevation modeling to support a geospatial framework for assessing changes in refugia for aquatic species in four rivers in western Kansas between 1965 and 2005. Decreased frequency and duration of streamflow occurred in all rivers, but the extent of change depended on the geomorphology of the river basin and the extent of groundwater development. In the absence of streamflow, refugia for aquatic species were defined as the stream reaches below the phreatic surface of the regional aquifer. Changes in extent, location and degree of fragmentation of gaining reaches was found to be a strong predictor of surface water occurrence during drought and a robust hydrological template for the analysis of changes in recharge to alluvial and regional aquifers and riparian and aquatic habitat.

Technology transfer: Promoting irrigation progress and best management practices

Science.gov (United States)

Educational efforts promoting irrigation best management practices are designed to increase adoption of these practices and increase public understanding of the importance of irrigation. They increase visibility and the impact of the Ogallala Aquifer Program and promote affiliated research and exten...

Coastal aquifer management under parameter uncertainty: Ensemble surrogate modeling based simulation-optimization

Science.gov (United States)

Janardhanan, S.; Datta, B.

2011-12-01

Surrogate models are widely used to develop computationally efficient simulation-optimization models to solve complex groundwater management problems. Artificial intelligence based models are most often used for this purpose where they are trained using predictor-predictand data obtained from a numerical simulation model. Most often this is implemented with the assumption that the parameters and boundary conditions used in the numerical simulation model are perfectly known. However, in most practical situations these values are uncertain. Under these circumstances the application of such approximation surrogates becomes limited. In our study we develop a surrogate model based coupled simulation optimization methodology for determining optimal pumping strategies for coastal aquifers considering parameter uncertainty. An ensemble surrogate modeling approach is used along with multiple realization optimization. The methodology is used to solve a multi-objective coastal aquifer management problem considering two conflicting objectives. Hydraulic conductivity and the aquifer recharge are considered as uncertain values. Three dimensional coupled flow and transport simulation model FEMWATER is used to simulate the aquifer responses for a number of scenarios corresponding to Latin hypercube samples of pumping and uncertain parameters to generate input-output patterns for training the surrogate models. Non-parametric bootstrap sampling of this original data set is used to generate multiple data sets which belong to different regions in the multi-dimensional decision and parameter space. These data sets are used to train and test multiple surrogate models based on genetic programming. The ensemble of surrogate models is then linked to a multi-objective genetic algorithm to solve the pumping optimization problem. Two conflicting objectives, viz, maximizing total pumping from beneficial wells and minimizing the total pumping from barrier wells for hydraulic control of

Climate variability and Great Plains agriculture

International Nuclear Information System (INIS)

Rosenberg, N.J.; Katz, L.A.

1991-01-01

The ways in which inhabitants of the Great Plains, including Indians, early settlers, and 20th century farmers, have adapted to climate changes on the Great Plains are explored. The climate of the Great Plains, because of its variability and extremes, can be very stressful to plants, animals and people. It is suggested that agriculture and society on the Great Plains have, during the last century, become less vulnerable to the stresses imposed by climate. Opinions as to the sustainability of agriculture on the Great Plains vary substantially. Lockeretz (1981) suggests that large scale, high cost technologies have stressed farmers by creating surpluses and by requiring large investments. Opie (1989) sees irrigation as a climate substitute, however he stresses that the Ogallala aquifer must inevitably become depleted. Deborah and Frank Popper (1987) believe that farming on the Plains is unsustainable, and destruction of shelterbelts, out-migration of the rural population and environmental problems will lead to total collapse. With global warming, water in the Great Plains is expected to become scarcer, and although improvements in irrigation efficiency may slow depletion of the Ogallala aquifer, ultimately the acreage under irrigation must decrease to levels that can be sustained by natural recharge and reliable surface flows. 23 refs., 2 figs

Water use, canopy temperature, lint yield, and fiber quality response of six upland cotton cultivars to water stress

Science.gov (United States)

The declining saturated thickness of the Ogallala Aquifer combined with the unpredictability of precipitation during the growing season in the Southern High Plains has resulted in elevated production risks associated with short-term crop water deficits. Cotton (Gossypium spp.) cultivars that can use...

Circles of live buffer strips in a center pivot to improve multiple ecosystem services and sustainability of irrigated agriculture in the southern great plains

Science.gov (United States)

Declining Ogallala Aquifer has threatened sustainability of highly productive irrigated agriculture in the region. The region, known for the dust bowl of thirties, is scared of its return. Lower well outputs and increasing pumping costs have compelled farmers to adapt alternative conservation strate...

Bioavailability and biodegradation of weathered diesel fuel in aquifer material under denitrifying conditions

International Nuclear Information System (INIS)

Bregnard, T.P.A.; Hoehener, P.; Zeyer, J.

1998-01-01

During the in situ bioremediation of a diesel fuel-contaminated aquifer in Menziken, Switzerland, aquifer material containing weathered diesel fuel (WDF) and indigenous microorganisms was excavated. This material was used to identify factors limiting WDF biodegradation under denitrifying conditions. Incubations of this material for 360 to 390 d under denitrifying conditions resulted in degradation of 23% of the WDF with concomitant consumption of NO 3 - and production of inorganic carbon. The biodegradation of WDF and the rate of NO 3 - consumption was stimulated by agitation of the microcosms. Biodegradation was not stimulated by the addition of a biosurfactant (rhamnolipids) or a synthetic surfactant (Triton X-100) at concentrations above their critical micelle concentrations. The rhamnolipids were biodegraded preferentially to WDF, whereas Triton X-100 was not degraded. Both surfactants reduced the surface tension of the growth medium from 72 to <35 dynes/cm and enhanced the apparent aqueous solubility of the model hydrocarbon n-hexadecane by four orders of magnitude. Solvent-extracted WDF, added at a concentration equal to that already present in the aquifer material, was also biodegraded by the microcosms, but not at a higher rate than the WDF already present in the material. The results show that the denitrifying biodegradation of WDF is not necessarily limited by bioavailability but rather by the inherent recalcitrance of WDF

Effects of regional groundwater flow on the performance of an aquifer thermal energy storage system under continuous operation

Science.gov (United States)

Lee, Kun Sang

2014-01-01

Numerical investigations and a thermohydraulic evaluation are presented for two-well models of an aquifer thermal energy storage (ATES) system operating under a continuous flow regime. A three-dimensional numerical model for groundwater flow and heat transport is used to analyze the thermal energy storage in the aquifer. This study emphasizes the influence of regional groundwater flow on the heat transfer and storage of the system under various operation scenarios. For different parameters of the system, performances were compared in terms of the temperature of recovered water and the temperature field in the aquifer. The calculated temperature at the producing well varies within a certain range throughout the year, reflecting the seasonal (quarterly) temperature variation of the injected water. The pressure gradient across the system, which determines the direction and velocity of regional groundwater flow, has a substantial influence on the convective heat transport and performance of aquifer thermal storage. Injection/production rate and geometrical size of the aquifer used in the model also impact the predicted temperature distribution at each stage and the recovery water temperature. The hydrogeological-thermal simulation is shown to play an integral part in the prediction of performance of processes as complicated as those in ATES systems.

Distribution of moisture, tritium, and plutonium in the alluvium, aquifer, and underlying tuff in Mortandad Canyon

International Nuclear Information System (INIS)

Purtymun, W.D.; Maes, M.N.; Peters, R.

1985-01-01

A study of the distribution of moisture, tritium, and plutonium in the Mortandad Canyon aquifer indicates some infiltration of water into the underlying tuff. This infiltration was accompanied by similar movement of tritium. The concentrations of plutonium on the sediments in the aquifer were low when compared with the high concentrations in solution in an ionic complex that does not readily exchange or is adsorbed by clay minerals in the alluvium. 2 references, 4 figures, 2 tables

Compilation of the Dakota Aquifer Project isotope data and publications: The Isotope Hydrology Program of the Isotope Sciences Division

International Nuclear Information System (INIS)

Davisson, M.L.; Smith, D.K.; Hudson, G.B.; Niemeyer, S.; Macfarlane, P.A.; Whittemore, D.O.

1995-01-01

In FY92 the then Nuclear Chemistry Division embarked on a scientific collaboration with the Kansas Geological Survey (KGS) to characterize with isotope techniques groundwater of the Dakota Formation of Kansas. The Dakota Formation is a Cretaceous-aged marine sandstone hosting potable groundwater in most regions of Kansas whose use will serve to partially offset the severe overdraft problems in the overlying Ogallala Formation. The isotope characterization of the Dakota groundwater has generated data that delineates sources, ages, and subsurface controls on the water quality. Initial interpretations of the data have been published in abstract volumes of (1) the 1993 Geological Society of America National Meeting, (2) the 8th International Conference on Geochronology, Cosmochronology and Isotope Geology, and (3) the 1994 Dakota Aquifer Workshop and Clinic. Copies of all abstracts are included in this brief review. One report will focus on the sources and ages of the groundwater, and the other will focus on the subsurface controls on the natural water quality

Kansas trends and changes in temperature, precipitation, drought, and frost-free days from the 1890s to 2015

Science.gov (United States)

Kansas extends 660 km from the moderate elevations and semi-humid conditions of the Lower Missouri Basin to the High Plains lying above the Ogallala aquifer and along the Rockies’ eastern slope. Such characteristics result in significant climate variability across the state, making timely and accura...

Agribusiness: Industry Study Final Report, AY 2003-2004, Seminar 1

Science.gov (United States)

2004-01-01

of the World Trade Organization (WTO) met in Doha, Qatar , and agreed to negotiate the liberalization of agricultural trade. The use of subsidies is...Marsh, Thomas L., Jeffrey M. Peterson and Jeffrey R. Williams, “Conserving the Ogallala Aquifer : Efficiency, Equity, and Moral Motives,” Choices

Residue management increases fallow water conservation and yield deficit irrigated crops grown in rotation with wheat

Science.gov (United States)

No-tillage (NT) residue management provides cover to increase precipitation capture compared with disk tillage (DT) or in the absence of a cover crop. Therefore, NT has the potential to reduce irrigation withdrawals from the declining Ogallala Aquifer. In a 4-year study, we quantified DT and NT effe...

Multiple isotopes (O, C, Li, Sr) as tracers of CO2 and brine leakage from CO2-enhanced oil recovery activities in Permian Basin, Texas, USA

Science.gov (United States)

Phan, T. T.; Sharma, S.; Gardiner, J. B.; Thomas, R. B.; Stuckman, M.; Spaulding, R.; Lopano, C. L.; Hakala, A.

2017-12-01

Potential CO2 and brine migration or leakage into shallow groundwater is a critical issue associated with CO2 injection at both enhanced oil recovery (EOR) and carbon sequestration sites. The effectiveness of multiple isotope systems (δ18OH2O, δ13C, δ7Li, 87Sr/86Sr) in monitoring CO2 and brine leakage at a CO2-EOR site located within the Permian basin (Seminole, Texas, USA) was studied. Water samples collected from an oil producing formation (San Andres), a deep groundwater formation (Santa Rosa), and a shallow groundwater aquifer (Ogallala) over a four-year period were analyzed for elemental and isotopic compositions. The absence of any change in δ18OH2O or δ13CDIC values of water in the overlying Ogallala aquifer after CO2 injection indicates that injected CO2 did not leak into this aquifer. The range of Ogallala water δ7Li (13-17‰) overlaps the San Andres water δ7Li (13-15‰) whereas 87Sr/86Sr of Ogallala (0.70792±0.00005) significantly differs from San Andres water (0.70865±0.00003). This observation demonstrates that Sr isotopes are much more sensitive than Li isotopes in tracking brine leakage into shallow groundwater at the studied site. In contrast, deep groundwater δ7Li (21-25‰) is isotopically distinct from San Andres produced water; thus, monitoring this intermitted formation water can provide an early indication of CO2 injection-induced brine migration from the underlying oil producing formation. During water alternating with gas (WAG) operations, a significant shift towards more positive δ13CDIC values was observed in the produced water from several of the San Andres formation wells. The carbon isotope trend suggests that the 13C enriched injected CO2 and formation carbonates became the primary sources of dissolved inorganic carbon in the area surrounding the injection wells. Moreover, one-way ANOVA statistical analysis shows that the differences in δ7Li (F(1,16) = 2.09, p = 0.17) and 87Sr/86Sr (F(1,18) = 4.47, p = 0.05) values of

Reaction of subsurface coastal aquifers to climate and land use changes in Greece: modelling of groundwater refreshening patterns under natural recharge conditions

Science.gov (United States)

Lambrakis, N.; Kallergis, G.

2001-05-01

This paper studies the multicomponent ion exchange process and freshening time under natural recharge conditions for three coastal aquifers in Greece. Due to over-pumping and the dry years of 1980-1990 decline in groundwater quality has been observed in most of the Greek coastal aquifers. This decline is caused by a lack of reliable water resource management, water abstraction from great depths, and seawater intrusion resulting in a rise of the fresh/salt water interface (salinisation process) due to a negative water balance. The reverse phenomenon, which should lead to groundwater freshening, is a long process. The freshening process shows chromatographic patterns that are due to chemical reactions such as calcite dissolution and cation exchange, and simultaneously occurring transport and dispersion processes. Using the geochemical simulation codes PHREEQE and PHREEQM (Parkhurst et al., US Geol. Surv. Water Resour. Invest., 80-96 (1980) 210; Appelo and Postma, Geochemistry, Groundwater and Pollution (1994)), these patterns were analysed and the above-mentioned processes were simulated for carefully selected aquifers in Peloponnesus and Crete (Greece). Aquifers of the Quaternary basin of Glafkos in Peloponnesus, the Neogene formations in Gouves, Crete, and the carbonate aquifer of Malia, Crete, were examined as representative examples of Greek coastal aquifer salinisation. The results show that when pumping was discontinued, the time required for freshening under natural conditions of the former two aquifers is long and varies between 8000 and 10,000 years. The Malia aquifer on the other hand, has a freshening time of 15 years. Freshening time was shown to depend mainly on cation exchange capacities and the recharge rate of the aquifers.

MICROBIAL DEGRADATION OF NITROGEN, OXYGEN AND SULFUR HETEROCYCLIC COMPOUNDS UNDER ANAEROBIC CONDITIONS: STUDIES WITH AQUIFER SAMPLES

Science.gov (United States)

The potential for anaerobic biodegradation of 12 heterocyclic model compounds was studied. Nine of the model compounds were biotransformed in aquifer slurries under sulfate-reducing or methanogenic conditions. The nitrogen and oxygen heterocyclic compounds were more susceptible t...

Hydrogeology and geochemistry of aquifers underlying the San Lorenzo and San Leandro areas of the East Bay Plain, Alameda County, California

Science.gov (United States)

Izbicki, John A.; Borchers, James W.; Leighton, David A.; Kulongoski, Justin T.; Fields, Latoya; Galloway, Devin L.; Michel, Robert L.

2003-01-01

The East Bay Plain, on the densely populated eastern shore of San Francisco Bay, contains an upper aquifer system to depths of 250 feet below land surface and an underlying lower aquifer system to depths of more than 650 feet. Injection and recovery of imported water has been proposed for deep aquifers at two sites within the lower aquifer system. Successful operation requires that the injected water be isolated from surface sources of poor-quality water during storage and recovery. Hydraulic, geochemical, and isotopic data were used to evaluate the isolation of deeper aquifers. Ground-water responses to tidal changes in the Bay suggest that thick clay layers present within these deposits effectively isolate the deeper aquifers in the northern part of the study area from overlying surficial deposits. These data also suggest that the areal extent of the shallow and deep aquifers beneath the Bay may be limited in the northern part of the study area. Despite its apparent hydraulic isolation, the lower aquifer system may be connected to the overlying upper aquifer system through the corroded and failed casings of abandoned wells. Water-level measurements in observation wells and downward flow measured in selected wells during nonpumped conditions suggest that water may flow through wells from the upper aquifer system into the lower aquifer system during nonpumped conditions. The chemistry of water from wells in the East Bay Plain ranges from fresh to saline; salinity is greater than seawater in shallow estuarine deposits near the Bay. Water from wells completed in the lower aquifer system has higher pH, higher sodium, chloride, and manganese concentrations, and lower calcium concentrations and alkalinity than does water from wells completed in the overlying upper aquifer system. Ground-water recharge temperatures derived from noble-gas data indicate that highly focused recharge processes from infiltration of winter streamflow and more diffuse recharge processes from

Hydrology of the Claiborne aquifer and interconnection with the Upper Floridan aquifer in southwest Georgia

Science.gov (United States)

Gordon, Debbie W.; Gonthier, Gerard

2017-04-24

The U.S. Geological Survey conducted a study, in cooperation with the Georgia Environmental Protection Division, to define the hydrologic properties of the Claiborne aquifer and evaluate its connection with the Upper Floridan aquifer in southwest Georgia. The effort involved collecting and compiling hydrologic data from the aquifer in subarea 4 of southwestern Georgia. Data collected for this study include borehole geophysical logs in 7 wells, and two 72-hour aquifer tests to determine aquifer properties.The top of the Claiborne aquifer extends from an altitude of about 200 feet above the North American Vertical Datum of 1988 (NAVD 88) in Terrell County to 402 feet below NAVD 88 in Decatur County, Georgia. The base of the aquifer extends from an altitude of about 60 feet above NAVD 88 in eastern Sumter County to about 750 feet below NAVD 88 in Decatur County. Aquifer thickness ranges from about 70 feet in eastern Early County to 400 feet in Decatur County.The transmissivity of the Claiborne aquifer, determined from two 72-hour aquifer tests, was estimated to be 1,500 and 700 feet squared per day in Mitchell and Early Counties, respectively. The storage coefficient was estimated to be 0.0006 and 0.0004 for the same sites, respectively. Aquifer test data from Mitchell County indicate a small amount of leakage occurred during the test. Groundwater-flow models suggest that the source of the leakage was the underlying Clayton aquifer, which produced about 2.5 feet of drawdown in response to pumping in the Claiborne aquifer. The vertical hydraulic conductivity of the confining unit between the Claiborne and Clayton aquifers was simulated to be about 0.02 foot per day.Results from the 72-hour aquifer tests run for this study indicated no interconnection between the Claiborne and overlying Upper Floridan aquifers at the two test sites. Additional data are needed to monitor the effects that increased withdrawals from the Claiborne aquifer may have on future water resources.

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.)

Site study plan for Upper Aquifer Hydrology Clusters, Deaf Smith County Site, Texas: Surface-based geotechnical field program: Preliminary draft

International Nuclear Information System (INIS)

1988-01-01

As part of site characterization studies, at the Deaf Smith County site, Texas, 15 wells at 5 locations will be completed in the Ogallala Formation and Dockum Group. The purposes of the wells, which are called Upper Aquifer (2) establish background hydrologic and water quality conditions, (3) provide analysis, (4) monitor responses of the shallow hydrologic system to site activities and nearby pumpage for irrigation, (5) collect water samples from both saturated and unsaturated materials to help define recharge rates and ground-water flow patterns, (6) monitor variations on water quality, and (7) define ground-water resources near the site. The test wells will be installed during a 14-month period starting about 1-1/2 years after site characterization activities begin. The Technical Field Services Contractor is responsible for conducting the field program of drilling and testing. Samples and data will be handled and reported in accordance with established Salt Repository Project procedures. A quality assurance program will assure that activities affecting quality are performed correctly and that the appropriate documentation is maintained. 44 refs., 19 figs., 5 tabs

Behaviour and fate of nine recycled water trace organics during managed aquifer recharge in an aerobic aquifer

Science.gov (United States)

Patterson, B. M.; Shackleton, M.; Furness, A. J.; Bekele, E.; Pearce, J.; Linge, K. L.; Busetti, F.; Spadek, T.; Toze, S.

2011-03-01

The fate of nine trace organic compounds was evaluated during a 12 month large-scale laboratory column experiment. The columns were packed with aquifer sediment and evaluated under natural aerobic and artificial anaerobic geochemical conditions, to assess the potential for natural attenuation of these compounds during aquifer passage associated with managed aquifer recharge (MAR). The nine trace organic compounds were bisphenol A (BPA), 17β-estradiol (E2), 17α-ethynylestradiol (EE2), N-nitrosodimethylamine (NDMA), N-nitrosomorpholine (NMOR), carbamazepine, oxazepam, iohexol and iodipamide. In the low organic carbon content Spearwood sediment, all trace organics were non-retarded with retardation coefficients between 1.0 and 1.2, indicating that these compounds would travel at near groundwater velocities within the aquifer. The natural aerobic geochemical conditions provided a suitable environment for the rapid degradation for BPA, E2, iohexol (half life NDMA and NMOR) did not degrade under either aerobic or anaerobic aquifer geochemical conditions (half life > 50 days). Field-based validation experiments with carbamazepine and oxazepam also showed no degradation. If persistent trace organics are present in recycled waters at concentrations in excess of their intended use, natural attenuation during aquifer passage alone may not result in extracted water meeting regulatory requirements. Additional pre treatment of the recycled water would therefore be required.

Aquifers in coastal reclaimed lands - real world assessments

Science.gov (United States)

Saha, A.; Bironne, A.; Vonhögen-Peeters, L.; Lee, W. K.; Babovic, V. M.; Vermeulen, P.; van Baaren, E.; Karaoulis, M.; Blanchais, F.; Nguyen, M.; Pauw, P.; Doornenbal, P.

2017-12-01

Climate change and population growth are significant concerns in coastal regions around the world, where more than 30% of the world's population reside. The numbers continue to rise as coastal areas are increasingly urbanized. Urbanization creates land shortages along the coasts, which has spurred coastal reclamation activities as a viable solution. In this study, we focus on these reclamation areas; reclaimed areas in Singapore, and in the Netherlands, and investigate the potential of these reclaimed bodies as artificial aquifers that could attenuate water shortage problems in addition to their original purpose. We compare how the reclamation methods determine the hydrogeological characteristics of these manmade aquifers. We highlight similarities in freshwater lens development in the artificial shallow aquifers under natural recharge under diverse conditions, i.e. tropical and temperate zones, using numerical models. The characteristics and responses of these aquifers with dynamic freshwater-saltwater interface are contrasted against naturally occurring coastal aquifers where equilibrium was disturbed by anthropogenic activities. Finally, we assess the risks associated with subsidence and saltwater intrusion, combining measurements and numerical models, in case these aquifers are planned for Aquifer Storage and Recovery (ASR) or Managed Aquifer Recharge (MAR) strategies. Relative performances of some ASR schemes are simulated and compared in the reclaimed lands.

A two-dimensional analytical model for groundwater flow in a leaky aquifer extending finite distance under the estuary

Science.gov (United States)

Chuang, Mo-Hsiung; Hung, Chi-Tung; -Yen Lin, Wen; Ma, Kuo-chen

2017-04-01

In recent years, cities and industries in the vicinity of the estuarine region have developed rapidly, resulting in a sharp increase in the population concerned. The increasing demand for human activities, agriculture irrigation, and aquaculture relies on massive pumping of water in estuarine area. Since the 1950s, numerous studies have focused on the effects of tidal fluctuations on groundwater flow in the estuarine area. Tide-induced head fluctuation in a two-dimensional estuarine aquifer system is complicated and rather important in dealing with many groundwater management or remediation problems. The conceptual model of the aquifer system considered is multi-layered with estuarine bank and the leaky aquifer extend finite distance under the estuary. The solution of the model describing the groundwater head distribution in such an estuarine aquifer system and subject to the tidal fluctuation effects from estuarine river is developed based on the method of separation of variables along with river boundary. The solutions by Sun (Sun H. A two-dimensional analytical solution of groundwater response to tidal loading in an estuary, Water Resour. Res. 1997; 33:1429-35) as well as Tang and Jiao (Tang Z. and J. J. Jiao, A two-dimensional analytical solution for groundwater flow in a leaky confined aquifer system near open tidal water, Hydrological Processes, 2001; 15: 573-585) can be shown to be special cases of the present solution. On the basis of the analytical solution, the groundwater head distribution in response to estuarine boundary is examined and the influences of leakage, hydraulic parameters, and loading effect on the groundwater head fluctuation due to tide are investigated and discussed. KEYWORDS: analytical model, estuarine river, groundwater fluctuation, leaky aquifer.

Two-dimensional finite element solution for the simultaneous transport of water and solutes through a nonhomogeneous aquifer under transient saturated unsaturated flow conditions

International Nuclear Information System (INIS)

Gureghian, A.B.

1979-01-01

A mathematical model of ground water transport through an aquifer is presented. The solute of interest is a metal tracer or radioactive material which may undergo decay through a sorbing unconfined aquifer. The subject is developed under the following headings: flow equation, solute equation, boundary conditions, finite element formulation, element formulation, solution scheme (flow equation, solute equation), results and discussions, water movement in a ditch drained aquifer under transient state, water and solute movement in a homogeneous and unsaturated soil, transport of 226 Ra in nonhomogeneous aquifer, tailings pond lined, and tailings pond unlined. It is concluded that this mathematical model may have a wide variety of applications. The uranium milling industry may find it useful to evaluate the hydrogeological suitability of their disposal sites. It may prove suited for the design of clay disposal ponds destined to hold hazardous liquids. It may also provide a means of estimating the long-term impact of radionuclides or other pollutants on the quality of ground water. 31 references, 9 figures, 3 tables

Geohydrology of the Cerro Prieto geothermal aquifer

Energy Technology Data Exchange (ETDEWEB)

Sanchez R, J.; de la Pena L, A.

1981-01-01

The most recent information on the Cerro Prieto geothermal aquifer is summarized, with special emphasis on the initial production zone where the wells completed in the Alpha aquifer are located. These wells produce steam for power plant units 1 and 2. Brief comments also are made on the Beta aquifer, which underlies the Alpha aquifer in the Cerro Prieto I area and which extends to the east to what is known as the Cerro Prieto II and Cerro Prieto III areas. The location of the area studied is shown. The Alpha and Beta aquifers differ in their mineralogy and cementing mineral composition, temperatures, and piezometric levels. The difference in piezometric levels indicates that there is no local communication between the two aquifers. This situation has been verified by a well interference test, using well E-1 as a producer in the Beta aquifer and well M-46 as the observation well in the Alpha aquifer. No interference between them was observed. Information on the geology, geohydrology, and geochemistry of Cerro Prieto is presented.

Recharge and Aquifer Response: Manukan Island’s Aquifer, Sabah, Malaysia

Directory of Open Access Journals (Sweden)

Sarva Mangala Praveena

2010-01-01

Full Text Available Manukan Island is a small island located in North-West of Sabah, Malaysia was used as a case study area for numerical modeling of an aquifer response to recharge and pumping rates. The results in this study present the variations of recharge into the aquifer under the prediction simulations. The recharge rate increases the water level as indicated by hydraulic heads. This shows that it can alter groundwater of Manukan Island which has been suffering from an overexploration in its unconfined the aquifer. The increase in recharge rate (from 600 mm/year to 750 mm/year increases the water level indicated by hydraulic heads. A reduction in pumping rate (from 0.072 m3/day to 0.058 m3/day not only increases the amount of water levels in aquifer but also reduces the supply hence a deficit in supply. The increase in hydraulic heads depends on the percentage reduction of pumping and recharges rates. The well water has 1978.3 mg/L chloride with current pumping (0.072 m3/day and recharge rates (600 mm/year. However, with an increased of recharge rate and current pumping rate it has decreased about 1.13%. In addition, reduction in pumping rate made the chloride concentration decreased about 2.8%. In general, a reduction in pumping with an increase in recharge rate leads to a decreased in chloride concentrations within the vicinity of cone of depression. Next, to further develop the numerical model, the model should focus on climate change variables such as consequences of climate change are increase in air temperature, increase in sea surface temperature, and more extreme weather conditions. These parameters are considered critical parameters for climate change impact modeling in aquifers. The behavior of the aquifer and its sustainable pumping rate can be done by applying a computer modeling component.

Vertical gradients in water chemistry and age in the Northern High Plains Aquifer, Nebraska, 2003

Science.gov (United States)

McMahon, P.B.; Böhlke, J.K.; Carney, C.P.

2007-01-01

and clay-mineral precipitation; organic-carbon and pyrite oxidation; oxygen reduction and denitrification; and cation exchange. Mixing with surface water affected the chemistry of ground water in alluvial sediments of the Platte River Valley. Radiocarbon ages in the aquifer, adjusted for carbon mass transfers, ranged from 1,800 to 15,600 14C years before present. These results have important implications with respect to development of ground-water resources in the Sand Hills. Most of the water in the aquifer predates modern anthropogenic activity so excessive removal of water by pumping is not likely to be replenished by natural recharge in a meaningful timeframe. Vertical gradients in ground-water age were used to estimate long-term average recharge rates in the aquifer. In most areas, the recharge rates ranged from 0.02 to 0.05 foot per year. The recharge rate was 0.2 foot per year in one part of the aquifer characterized by large downward hydraulic gradients.Nitrite plus nitrate concentrations at the water table were 0.13 to 3.13 milligrams per liter as nitrogen, and concentrations substantially decreased with depth in the aquifer. Dissolved-gas and nitrogen-isotope data indicate that denitrification in the aquifer removed 0 to 97 percent (average = 50 percent) of the nitrate originally present in recharge. The average amount of nitrate removed by denitrification in the aquifer north of the Platte River (Sand Hills) was substantially greater than the amount removed south of the river (66 as opposed to 0 percent), and the extent of nitrate removal appears to be related to the presence of thick deposits of sediment on top of the Ogallala Group in the Sand Hills that contained electron donors, such as organic carbon and pyrite, to support denitrification.Apparent rates of dissolved-oxygen reduction and denitrification were estimated on the basis of decreases in dissolved-oxygen concentrations and increases in concentrations of excess nitrogen gas and ground-water ages

Soil aquifer treatment of artificial wastewater under saturated conditions

KAUST Repository

Essandoh, H. M K

2011-05-01

A 2000 mm long saturated laboratory soil column was used to simulate soil aquifer treatment under saturated conditions to assess the removal of chemical and biochemical oxygen demand (COD and BOD), dissolved organic carbon (DOC), nitrogen and phosphate, using high strength artificial wastewater. The removal rates were determined under a combination of constant hydraulic loading rates (HLR) and variable COD concentrations as well as variable HLR under a constant COD. Within the range of COD concentrations considered (42 mg L-1-135 mg L-1) it was found that at fixed hydraulic loading rate, a decrease in the influent concentrations of dissolved organic carbon (DOC), biochemical oxygen demand (BOD), total nitrogen and phosphate improved their removal efficiencies. At the high COD concentrations applied residence times influenced the redox conditions in the soil column. Long residence times were detrimental to the removal process for COD, BOD and DOC as anoxic processes and sulphate reduction played an important role as electron acceptors. It was found that total COD mass loading within the range of 911 mg d-1-1780 mg d-1 applied as low COD wastewater infiltrated coupled with short residence times would provide better effluent quality than the same mass applied as a COD with higher concentration at long residence times. The opposite was true for organic nitrogen where relatively high concentrations coupled with long residence time gave better removal efficiency. © 2011.

Straddle-packer aquifer test analyses of the Snake River Plain aquifer at the Idaho National Engineering Laboratory

International Nuclear Information System (INIS)

Johnson, G.S.; Frederick, D.B.

1997-01-01

The State of Idaho INEL Oversight Program, with the University of Idaho, Idaho State University, Boise State University, and the Idaho Geologic Survey, used a straddle-packer system to investigate vertical variations in characteristics of the Snake River Plain aquifer at the Idaho National Engineering Laboratory in southeast Idaho. Sixteen single-well aquifer tests were conducted on.isolated intervals in three observation wells. Each of these wells has approximately 200 feet of open borehole below the water table, penetrating the E through G and I basalt flow groups and interbedded sediments of the Snake River Plain aquifer. The success of the aquifer tests was limited by the inability to induce measurable drawdown in several zones. Time-drawdown data from aquifer tests were matched to type curves for 8 of the 16 zones tested. A single aquifer test at the water table exhibited greater curvature than those at depth. The increased degree of curvature suggests an unconfined response and resulted in an estimate of specific yield of 0.03. Aquifer tests below the water table generally yielded time-drawdown graphs with a rapid initial response followed by constant drawdown throughout the duration of the tests; up to several hours in length. The rapid initial response implies that the aquifer responds as a confined system during brief pumping periods. The nearly constant drawdown suggests a secondary source of water, probably vertical flow from overlying and underlying aquifer layers. Three analytical models were applied for comparison to the conceptual model and to provide estimates of aquifer properties. This, Hantush-Jacob leaky aquifer, and the Moench double-porosity fractured rock models were fit to time-drawdown data. The leaky aquifer type curves of Hantush and Jacob generally provided the best match to observed drawdown. A specific capacity regression equation was also used to estimate hydraulic conductivity

Development of a stream–aquifer numerical flow model to assess river water management under water scarcity in a Mediterranean basin

International Nuclear Information System (INIS)

Mas-Pla, Josep; Font, Eva; Astui, Oihane; Menció, Anna; Rodríguez-Florit, Agustí; Folch, Albert; Brusi, David; Pérez-Paricio, Alfredo

2012-01-01

Stream flow, as a part of a basin hydrological cycle, will be sensible to water scarcity as a result of climate change. Stream vulnerability should then be evaluated as a key component of the basin water budget. Numerical flow modeling has been applied to an alluvial formation in a small mountain basin to evaluate the stream–aquifer relationship under these future scenarios. The Arbúcies River basin (116 km 2 ) is located in the Catalan Inner Basins (NE Spain) and its lower reach, which is related to an alluvial aquifer, usually becomes dry during the summer period. This study seeks to determine the origin of such discharge losses whether from natural stream leakage and/or induced capture due to groundwater withdrawal. Our goal is also investigating how discharge variations from the basin headwaters, representing potential effects of climate change, may affect stream flow, aquifer recharge, and finally environmental preservation and human supply. A numerical flow model of the alluvial aquifer, based on MODFLOW and especially in the STREAM routine, reproduced the flow system after the usual calibration. Results indicate that, in the average, stream flow provides more than 50% of the water inputs to the alluvial aquifer, being responsible for the amount of stored water resources and for satisfying groundwater exploitation for human needs. Detailed simulations using daily time-steps permit setting threshold values for the stream flow entering at the beginning of the studied area so surface discharge is maintained along the whole watercourse and ecological flow requirements are satisfied as well. The effects of predicted rainfall and temperature variations on the Arbúcies River alluvial aquifer water balance are also discussed from the outcomes of the simulations. Finally, model results indicate the relevance of headwater discharge management under future climate scenarios to preserve downstream hydrological processes. They also point out that small mountain basins

Apparent directional mass-transfer capacity coefficients in three-dimensional anisotropic heterogeneous aquifers under radial convergent transport

Science.gov (United States)

Pedretti, D.; Fernàndez-Garcia, D.; Sanchez-Vila, X.; Bolster, D.; Benson, D. A.

2014-02-01

Aquifer hydraulic properties such as hydraulic conductivity (K) are ubiquitously heterogeneous and typically only a statistical characterization can be sought. Additionally, statistical anisotropy at typical characterization scales is the rule. Thus, regardless of the processes governing solute transport at the local (pore) scale, transport becomes non-Fickian. Mass-transfer models provide an efficient tool that reproduces observed anomalous transport; in some cases though, these models lack predictability as model parameters cannot readily be connected to the physical properties of aquifers. In this study, we focus on a multirate mass-transfer model (MRMT), and in particular the apparent capacity coefficient (β), which is a strong indicator of the potential of immobile zones to capture moving solute. We aim to find if the choice of an apparent β can be phenomenologically related to measures of statistical anisotropy. We analyzed an ensemble of random simulations of three-dimensional log-transformed multi-Gaussian permeability fields with stationary anisotropic correlation under convergent flow conditions. It was found that apparent β also displays an anisotropic behavior, physically controlled by the aquifer directional connectivity, which in turn is controlled by the anisotropic correlation model. A high hydraulic connectivity results in large β values. These results provide new insights into the practical use of mass-transfer models for predictive purposes.

EPA Sole Source Aquifers

Data.gov (United States)

U.S. Environmental Protection Agency — Information on sole source aquifers (SSAs) is widely used in assessments under the National Environmental Policy Act and at the state and local level. A national...

Development of a stream-aquifer numerical flow model to assess river water management under water scarcity in a Mediterranean basin.

Science.gov (United States)

Mas-Pla, Josep; Font, Eva; Astui, Oihane; Menció, Anna; Rodríguez-Florit, Agustí; Folch, Albert; Brusi, David; Pérez-Paricio, Alfredo

2012-12-01

Stream flow, as a part of a basin hydrological cycle, will be sensible to water scarcity as a result of climate change. Stream vulnerability should then be evaluated as a key component of the basin water budget. Numerical flow modeling has been applied to an alluvial formation in a small mountain basin to evaluate the stream-aquifer relationship under these future scenarios. The Arbúcies River basin (116 km(2)) is located in the Catalan Inner Basins (NE Spain) and its lower reach, which is related to an alluvial aquifer, usually becomes dry during the summer period. This study seeks to determine the origin of such discharge losses whether from natural stream leakage and/or induced capture due to groundwater withdrawal. Our goal is also investigating how discharge variations from the basin headwaters, representing potential effects of climate change, may affect stream flow, aquifer recharge, and finally environmental preservation and human supply. A numerical flow model of the alluvial aquifer, based on MODFLOW and especially in the STREAM routine, reproduced the flow system after the usual calibration. Results indicate that, in the average, stream flow provides more than 50% of the water inputs to the alluvial aquifer, being responsible for the amount of stored water resources and for satisfying groundwater exploitation for human needs. Detailed simulations using daily time-steps permit setting threshold values for the stream flow entering at the beginning of the studied area so surface discharge is maintained along the whole watercourse and ecological flow requirements are satisfied as well. The effects of predicted rainfall and temperature variations on the Arbúcies River alluvial aquifer water balance are also discussed from the outcomes of the simulations. Finally, model results indicate the relevance of headwater discharge management under future climate scenarios to preserve downstream hydrological processes. They also point out that small mountain basins

Arsenic release during managed aquifer recharge (MAR)

Science.gov (United States)

Pichler, T.; Lazareva, O.; Druschel, G.

2013-12-01

The mobilization and addition of geogenic trace metals to groundwater is typically caused by anthropogenic perturbations of the physicochemical conditions in the aquifer. This can add dangerously high levels of toxins to groundwater, thus compromising its use as a source of drinking water. In several regions world-wide, aquifer storage and recovery (ASR), a form of managed aquifer recharge (MAR), faces the problem of arsenic release due to the injection of oxygenated storage water. To better understand this process we coupled geochemical reactive transport modeling to bench-scale leaching experiments to investigate and verify the mobilization of geogenic arsenic (As) under a range of redox conditions from an arsenic-rich pyrite bearing limestone aquifer in Central Florida. Modeling and experimental observations showed similar results and confirmed the following: (1) native groundwater and aquifer matrix, including pyrite, were in chemical equilibrium, thus preventing the release of As due to pyrite dissolution under ambient conditions; (2) mixing of oxygen-rich surface water with oxygen-depleted native groundwater changed the redox conditions and promoted the dissolution of pyrite, and (3) the behavior of As along a flow path was controlled by a complex series of interconnected reactions. This included the oxidative dissolution of pyrite and simultaneous sorption of As onto neo-formed hydrous ferric oxides (HFO), followed by the reductive dissolution of HFO and secondary release of adsorbed As under reducing conditions. Arsenic contamination of drinking water in these systems is thus controlled by the re-equilibration of the system to more reducing conditions rather than a purely oxidative process.

Intensively exploited Mediterranean aquifers: resilience and proximity to critical points of seawater intrusion

Science.gov (United States)

Mazi, K.; Koussis, A. D.; Destouni, G.

2013-11-01

We investigate here seawater intrusion in three prominent Mediterranean aquifers that are subject to intensive exploitation and modified hydrologic regimes by human activities: the Nile Delta Aquifer, the Israel Coastal Aquifer and the Cyprus Akrotiri Aquifer. Using a generalized analytical sharp-interface model, we review the salinization history and current status of these aquifers, and quantify their resilience/vulnerability to current and future sea intrusion forcings. We identify two different critical limits of sea intrusion under groundwater exploitation and/or climatic stress: a limit of well intrusion, at which intruded seawater reaches key locations of groundwater pumping, and a tipping point of complete sea intrusion upto the prevailing groundwater divide of a coastal aquifer. Either limit can be reached, and ultimately crossed, under intensive aquifer exploitation and/or climate-driven change. We show that sea intrusion vulnerability for different aquifer cases can be directly compared in terms of normalized intrusion performance curves. The site-specific assessments show that the advance of seawater currently seriously threatens the Nile Delta Aquifer and the Israel Coastal Aquifer. The Cyprus Akrotiri Aquifer is currently somewhat less threatened by increased seawater intrusion.

Semi-analytical solutions for flow to a well in an unconfined-fractured aquifer system

Science.gov (United States)

Sedghi, Mohammad M.; Samani, Nozar

2015-09-01

Semi-analytical solutions of flow to a well in an unconfined single porosity aquifer underlain by a fractured double porosity aquifer, both of infinite radial extent, are obtained. The upper aquifer is pumped at a constant rate from a pumping well of infinitesimal radius. The solutions are obtained via Laplace and Hankel transforms and are then numerically inverted to time domain solutions using the de Hoog et al. algorithm and Gaussian quadrature. The results are presented in the form of dimensionless type curves. The solution takes into account the effects of pumping well partial penetration, water table with instantaneous drainage, leakage with storage in the lower aquifer into the upper aquifer, and storativity and hydraulic conductivity of both fractures and matrix blocks. Both spheres and slab-shaped matrix blocks are considered. The effects of the underlying fractured aquifer hydraulic parameters on the dimensionless drawdown produced by the pumping well in the overlying unconfined aquifer are examined. The presented solution can be used to estimate hydraulic parameters of the unconfined and the underlying fractured aquifer by type curve matching techniques or with automated optimization algorithms. Errors arising from ignoring the underlying fractured aquifer in the drawdown distribution in the unconfined aquifer are also investigated.

Assessing Climate Change Impacts on Water Resources and Colorado Agriculture Using an Equilibrium Displacement Mathematical Programming Model

OpenAIRE

Fathelrahman, Eihab; Davies, Amalia; Davies, Stephen; Pritchett, James

2014-01-01

This research models selected impacts of climate change on Colorado agriculture several decades in the future, using an Economic Displacement Mathematical Programming model. The agricultural economy in Colorado is dominated by livestock, which accounts for 67% of total receipts. Crops, including feed grains and forages, account for the remainder. Most agriculture is based on irrigated production, which depends on both groundwater, especially from the Ogallala aquifer, and surface water that c...

Behaviour and fate of nine recycled water trace organics during managed aquifer recharge in an aerobic aquifer.

Science.gov (United States)

Patterson, B M; Shackleton, M; Furness, A J; Bekele, E; Pearce, J; Linge, K L; Busetti, F; Spadek, T; Toze, S

2011-03-25

The fate of nine trace organic compounds was evaluated during a 12month large-scale laboratory column experiment. The columns were packed with aquifer sediment and evaluated under natural aerobic and artificial anaerobic geochemical conditions, to assess the potential for natural attenuation of these compounds during aquifer passage associated with managed aquifer recharge (MAR). The nine trace organic compounds were bisphenol A (BPA), 17β-estradiol (E2), 17α-ethynylestradiol (EE2), N-nitrosodimethylamine (NDMA), N-nitrosomorpholine (NMOR), carbamazepine, oxazepam, iohexol and iodipamide. In the low organic carbon content Spearwood sediment, all trace organics were non-retarded with retardation coefficients between 1.0 and 1.2, indicating that these compounds would travel at near groundwater velocities within the aquifer. The natural aerobic geochemical conditions provided a suitable environment for the rapid degradation for BPA, E2, iohexol (half life aquifer geochemical conditions (half life >50days). Field-based validation experiments with carbamazepine and oxazepam also showed no degradation. If persistent trace organics are present in recycled waters at concentrations in excess of their intended use, natural attenuation during aquifer passage alone may not result in extracted water meeting regulatory requirements. Additional pre treatment of the recycled water would therefore be required. Crown Copyright © 2010. Published by Elsevier B.V. All rights reserved.

CO2/Brine transport into shallow aquifers along fault zones.

Science.gov (United States)

Keating, Elizabeth H; Newell, Dennis L; Viswanathan, Hari; Carey, J W; Zyvoloski, G; Pawar, Rajesh

2013-01-02

Unintended release of CO(2) from carbon sequestration reservoirs poses a well-recognized risk to groundwater quality. Research has largely focused on in situ CO(2)-induced pH depression and subsequent trace metal mobilization. In this paper we focus on a second mechanism: upward intrusion of displaced brine or brackish-water into a shallow aquifer as a result of CO(2) injection. Studies of two natural analog sites provide insights into physical and chemical mechanisms controlling both brackish water and CO(2) intrusion into shallow aquifers along fault zones. At the Chimayó, New Mexico site, shallow groundwater near the fault is enriched in CO(2) and, in some places, salinity is significantly elevated. In contrast, at the Springerville, Arizona site CO(2) is leaking upward through brine aquifers but does not appear to be increasing salinity in the shallow aquifer. Using multiphase transport simulations we show conditions under which significant CO(2) can be transported through deep brine aquifers into shallow layers. Only a subset of these conditions favor entrainment of salinity into the shallow aquifer: high aspect-ratio leakage pathways and viscous coupling between the fluid phases. Recognition of the conditions under which salinity is favored to be cotransported with CO(2) into shallow aquifers will be important in environmental risk assessments.

Carbonate aquifers

Science.gov (United States)

Cunningham, Kevin J.; Sukop, Michael; Curran, H. Allen

2012-01-01

Only limited hydrogeological research has been conducted using ichnology in carbonate aquifer characterization. Regardless, important applications of ichnology to carbonate aquifer characterization include its use to distinguish and delineate depositional cycles, correlate mappable biogenically altered surfaces, identify zones of preferential groundwater flow and paleogroundwater flow, and better understand the origin of ichnofabric-related karst features. Three case studies, which include Pleistocene carbonate rocks of the Biscayne aquifer in southern Florida and Cretaceous carbonate strata of the Edwards–Trinity aquifer system in central Texas, demonstrate that (1) there can be a strong relation between ichnofabrics and groundwater flow in carbonate aquifers and (2) ichnology can offer a useful methodology for carbonate aquifer characterization. In these examples, zones of extremely permeable, ichnofabric-related macroporosity are mappable stratiform geobodies and as such can be represented in groundwater flow and transport simulations.

Principal aquifers can contribute radium to sources of drinking water under certain geochemical conditions

Science.gov (United States)

Szabo, Zoltan; Fischer, Jeffrey M.; Hancock, Tracy Connell

2012-01-01

What are the most important factors affecting dissolved radium concentrations in principal aquifers used for drinking water in the United States? Study results reveal where radium was detected and how rock type and chemical processes control radium occurrence. Knowledge of the geochemical conditions may help water-resource managers anticipate where radium may be elevated in groundwater and minimize exposure to radium, which contributes to cancer risk. Summary of Major Findings: * Concentrations of radium in principal aquifers used for drinking water throughout the United States generally were below 5 picocuries per liter (pCi/L), the U.S. Environmental Protection Agency (USEPA) maximum contaminant level (MCL) for combined radium - radium-226 (Ra-226) plus radium-228 (Ra-228) - in public water supplies. About 3 percent of sampled wells had combined radium concentrations greater than the MCL. * Elevated concentrations of combined radium were more common in groundwater in the eastern and central United States than in other regions of the Nation. About 98 percent of the wells that contained combined radium at concentrations greater than the MCL were east of the High Plains. * The highest concentrations of combined radium were in the Mid-Continent and Ozark Plateau Cambro-Ordovician aquifer system and the Northern Atlantic Coastal Plain aquifer system. More than 20 percent of sampled wells in these aquifers had combined radium concentrations that were greater than or equal to the MCL. * Concentrations of Ra-226 correlated with those of Ra-228. Radium-226 and Ra-228 occur most frequently together in unconsolidated sand aquifers, and their presence is strongly linked to groundwater chemistry. * Three common geochemical factors are associated with the highest radium concentrations in groundwater: (1) oxygen-poor water, (2) acidic conditions (low pH), and (3) high concentrations of dissolved solids.

Intensively exploited Mediterranean aquifers: resilience to seawater intrusion and proximity to critical thresholds

Science.gov (United States)

Mazi, K.; Koussis, A. D.; Destouni, G.

2014-05-01

We investigate seawater intrusion in three prominent Mediterranean aquifers that are subject to intensive exploitation and modified hydrologic regimes by human activities: the Nile Delta, Israel Coastal and Cyprus Akrotiri aquifers. Using a generalized analytical sharp interface model, we review the salinization history and current status of these aquifers, and quantify their resilience/vulnerability to current and future seawater intrusion forcings. We identify two different critical limits of seawater intrusion under groundwater exploitation and/or climatic stress: a limit of well intrusion, at which intruded seawater reaches key locations of groundwater pumping, and a tipping point of complete seawater intrusion up to the prevailing groundwater divide of a coastal aquifer. Either limit can be reached, and ultimately crossed, under intensive aquifer exploitation and/or climate-driven change. We show that seawater intrusion vulnerability for different aquifer cases can be directly compared in terms of normalized intrusion performance curves. The site-specific assessments show that (a) the intruding seawater currently seriously threatens the Nile Delta aquifer, (b) in the Israel Coastal aquifer the sharp interface toe approaches the well location and (c) the Cyprus Akrotiri aquifer is currently somewhat less threatened by increased seawater intrusion.

Hydrogeology and ground-water flow of the drift and Platteville aquifer system, St Louis Park, Minnesota

Science.gov (United States)

Lindgren, R.J.

1995-01-01

Three aquifers and two confining units have been delineated within the drift underlying the area near the site of a former coal-tar distillation and wood-preserving plant in St. Louis Park, Minnesota. The hydrogeologic units of the drift, in descending order, are the upper drift aquifer, the upper drift confining unit, the middle drift aquifer, the lower drift confining unit. and the lower drift aquifer. A contamination plume consisting of coal-tar derivatives exists in the drift aquifers and in the Platteville aquifer underlying the southern part of the plant site and areas to the south and east of the plant site.

Isotopic study of the Continental Intercalaire aquifer and its relationship with other aquifers of the northern Sahara

International Nuclear Information System (INIS)

Gonfiantini, R.; Sauzay, G.; Payne, B.R.; Conrad, G.; Fontes, J.Ch.

1974-01-01

The Northern Sahara contains several aquifers, the largest of which is that of the Continental Intercalaire formations. In its eastern part the aquifer is confined and presents a very homogeneous isotopic composition. The 14 C activity is low or zero except in the outcrop zones of the north (Saharan Atlas), the east (Dahar) and the south (Tinrhert), all of which are recharge zones. In these areas the isotopic composition does not differ appreciably from that of the old water in the confined part of the aquifer. In the western part, where the reservoir outcrops widely, the 14 C activities show the extent of the local recharge. The heavy isotope content indicates the overflow of the surface aquifer of the western Grand Erg into the Continental Intercalaire over the whole Gourara front. The mixtures thus formed pass under the Tademait and drain towards the Touat. In the resurgence zone of the Gulf of G abes in Tunisia the heavy-isotope content confirms the recharging of the aquifer of the Complex terminal by drainage of water from the Continental Intercalaire through the El-Hamma fault system. The water then runs eastwards, mixing with local contributions. The marine Miocene confined aquifer of Zarzis-Djerba in the Gulf of Gabes receives no contribution from the Continental Intercalaire. The water in the aquifer of the western Grand Erg indicates an evaporation mechanism, probably peculiar to the dune systems, which gives rise to heavy-isotope enrichment compared with the recharge of other types of formations. (author) [fr

A summary of the occurrence and development of ground water in the southern High Plains of Texas

Science.gov (United States)

Cronin, J.G.; Myers, B.N.

1964-01-01

quantities of water in many parts of the Southern High Pl'ains; however, in practically all places the water is rather saline and prOgallala formation, moderate quantitie of water are obtained, particularly from the limestones. Locally the Cretaceous rocks may be important aquifers where other water is not available, but they generally do not constitute a large source of water for irrigation or municipal use. The Ogallala formation of Pliocene age is the principal aquifer in the Southern High Plains of Texas; it supplies practically all the water used for all purposes. The formation is continuous throughout most of the Texas part of the Southern High Plains and extends into New Mexico. The .formation consists chiefly of sediments deposited by streams that had their headwaters in the mountainous regions to the west and northwest. The Ogallala formation rests unconformably upon an erosional surface of the underlying Triassic and Cretaceous rocks. The Ogallala consists of beds and lenses of clay, silt, sand, and gravel; caliche occurs as a secondary deposit ,in many places in the formation. In general the Ogallala is thicker in the northern part of the area; the thickness ranges from 400 to 500 feet in central Parmer, west-central Castro, and southwestern Floyd Counties to a knife edge where the formation wedges out against outcrops of the older rocks. The Ogallala formation probably originally formed a continuous blanket of sedimen

An Assessment of Regional Water Resources and Agricultural Sustainability in the Mississippi River Alluvial Aquifer System of Mississippi and Arkansas Under Current and Future Climate

Science.gov (United States)

Rigby, J.; Reba, M.

2011-12-01

The Lower Mississippi River Alluvial Plain is a highly productive agricultural region for rice, soy beans, and cotton that depends heavily on irrigation. Development of the Mississippi River Alluvial Aquifer (MRAA), one of the more prolific agricultural aquifers in the country, has traditionally been the primary source for irrigation in the region yielding over 1,100 Mgal/day to irrigation wells. Increasingly, the realities of changing climate and rapidly declining water tables have highlighted the necessity for new water management practices. Tail-water recovery and reuse is a rapidly expanding practice due in part to the efforts and cost-sharing of the NRCS, but regional studies of the potential for such practices to alleviate groundwater mining under current and future climate are lacking. While regional studies of aquifer geology have long been available, including assessments of regional groundwater flow, much about the aquifer is still not well understood including controls on recharge rates, a crucial component of water management design. We review the trends in regional availability of surface and groundwater resources, their current status, and the effects of recent changes in management practices on groundwater decline in Mississippi and Arkansas. Global and regional climate projections are used to assess scenarios of sustainable aquifer use under current land use and management along with the potential for more widely practiced surface water capture and reuse to alleviate groundwater decline. Finally, we highlight crucial knowledge gaps and challenges associated with the development of water management practices for sustainable agricultural use in the region.

Integrated Decision Tools for Sustainable Watershed/Ground Water and Crop Health using Predictive Weather, Remote Sensing, and Irrigation Decision Tools

Science.gov (United States)

Jones, A. S.; Andales, A.; McGovern, C.; Smith, G. E. B.; David, O.; Fletcher, S. J.

2017-12-01

US agricultural and Govt. lands have a unique co-dependent relationship, particularly in the Western US. More than 30% of all irrigated US agricultural output comes from lands sustained by the Ogallala Aquifer in the western Great Plains. Six US Forest Service National Grasslands reside within the aquifer region, consisting of over 375,000 ha (3,759 km2) of USFS managed lands. Likewise, National Forest lands are the headwaters to many intensive agricultural regions. Our Ogallala Aquifer team is enhancing crop irrigation decision tools with predictive weather and remote sensing data to better manage water for irrigated crops within these regions. An integrated multi-model software framework is used to link irrigation decision tools, resulting in positive management benefits on natural water resources. Teams and teams-of-teams can build upon these multi-disciplinary multi-faceted modeling capabilities. For example, the CSU Catalyst for Innovative Partnerships program has formed a new multidisciplinary team that will address "Rural Wealth Creation" focusing on the many integrated links between economic, agricultural production and management, natural resource availabilities, and key social aspects of govt. policy recommendations. By enhancing tools like these with predictive weather and other related data (like in situ measurements, hydrologic models, remotely sensed data sets, and (in the near future) linking to agro-economic and life cycle assessment models) this work demonstrates an integrated data-driven future vision of inter-meshed dynamic systems that can address challenging multi-system problems. We will present the present state of the work and opportunities for future involvement.

Karst connections between unconfined aquifers and the Upper Floridan aquifer in south Georgia: geophysical evidence and hydrogeological models

Science.gov (United States)

Thieme, D. M.; Denizman, C.

2011-12-01

Buried karst features in sedimentary rocks of the south Georgia Coastal Plain present a challenge for hydrogeological models of recharge and confined flow within the underlying Upper Floridan aquifer. The Withlacoochee River, the trunk stream for the area, frequently disappears into subsurface caverns as it makes its way south to join the Suwannee River in northern Florida. The Withlacoochee also receives inputs from small ponds and bays which in turn receive spring and seep groundwater inputs. We have mapped karst topography at the "top of rock" using ground-penetrating radar (GPR). Up to seven meters of relief is indicated for the paleotopography on Miocene to Pliocene rocks, contrasting with the more subdued relief of the modern landscape. Current stratigraphic and hydrogeological reconstructions do not incorporate this amount of relief or lateral variation in the confining beds. One "pipe" which is approximately four meters in diameter is being mapped in detail. We have field evidence at this location for rapid movement of surficial pond and river water with a meteoric signature through several separate strata of sedimentary rock into an aquifer in the Hawthorn formation. We use our geophysical and hydrological field evidence to constrain quantitative hydrogeological models for the flow rates into and out of both this upper aquifer and the underlying Upper Floridan aquifer, which is generally considered to be confined by the clays of the Hawthorn.

Unravelling aquifer-wetland interaction using CSAMT and gravity methods: the Mollina-Camorra aquifer and the Fuente de Piedra playa-lake, southern Spain

Science.gov (United States)

Pedrera, A.; Martos-Rosillo, S.; Galindo-Zaldívar, J.; Rodríguez-Rodríguez, M.; Benavente, J.; Martín-Rodríguez, J. F.; Zúñiga-López, M. I.

2016-06-01

The hydrological regime of Fuente de Piedra playa-lake (Málaga, southern Spain) has been significantly affected by the intensive exploitation of groundwater in the area. The playa-lake is situated above clays, marls, and gypsum, and under unaltered conditions received surface-subsurface runoff within the watershed as well as groundwater discharge from two carbonate aquifers. We have analyzed the structure of the main one, the Mollina-Camorra carbonate aquifer, by combining controlled source audio magnetotellurics (CSAMT), gravity prospecting, and time-domain electromagnetic (TDEM) soundings. This geophysical information, together with new structural and hydrogeological data, was gathered to develop a new conceptual hydrogeological model. This model allows the hydrological linkage of the carbonate aquifer with the playa-lake system to be established. Moreover, the intensive exploitation in the carbonate aquifer, even outside the watershed of the playa-lake, has affected the hydrological regime of the system. This multidisciplinary work demonstrates the potential of geophysical methods for understanding wetland-aquifer interaction, having important groundwater management implications.

Estimation of Hydraulic Parameters and Aquifer Properties for a Managed Aquifer Recharge Pilot Study in The Lower Mississippi River Basin

Science.gov (United States)

Ozeren, Y.; Rigby, J.; Holt, R. M.

2017-12-01

Mississippi River Valley Alluvial Aquifer (MRVAA) is the major irrigation water resource in the in the lower Mississippi River basin. MRVAA has been significantly depleted in the last two decades due to excessive pumping. A wide range of measures to ensure sustainable groundwater supply in the region is currently under investigation. One of the possible solution under consideration is to use Managed Aquifer Recharge (MAR) by artificial recharge. The proposed artificial recharge technique in this study is to collect water through bank filtration, transfer water via pipeline to the critically low groundwater areas by a set of injection wells. A pilot study in the area is underway to investigate the possibility of artificial recharge in the area. As part of this study, a pumping test was carried out on an existing irrigation well along banks of Tallahatchie River near Money, MS. Geophysical surveys were also carried out in the pilot study area. Hydraulic response of the observation wells was used to determine stream bed conductance and aquifer parameters. The collected hydraulic parameters and aquifer properties will provide inputs for small-scale, high-resolution engineering model for abstraction-injection hydraulics along river. Here, preliminary results of the pilot study is presented.

Ground-water quality of the surficial aquifer system and the upper Floridan Aquifer, Ocala National Forest and Lake County, Florida, 1990-99

Science.gov (United States)

Adamski, J.C.; Knowles, Leel

2001-01-01

Data from 217 ground-water samples were statistically analyzed to assess the water quality of the surficial aquifer system and Upper Floridan aquifer in the Ocala National Forest and Lake County, Florida. Samples were collected from 49 wells tapping the surficial aquifer system, 141 wells tapping the Upper Floridan aquifer, and from 27 springs that discharge water from the Upper Floridan aquifer. A total of 136 samples was collected by the U.S. Geological Survey from 1995 through 1999. These data were supplemented with 81 samples collected by the St. Johns River Water Management District and Lake County Water Resources Management from 1990 through 1998. In general, the surficial aquifer system has low concentrations of total dissolved solids (median was 41 milligrams per liter) and major ions. Water quality of the surficial aquifer system, however, is not homogeneous throughout the study area. Concentrations of total dissolved solids, many major ions, and nutrients are greater in samples from Lake County outside the Ocala National Forest than in samples from within the Forest. These results indicate that the surficial aquifer system in Lake County outside the Ocala National Forest probably is being affected by agricultural and (or) urban land-use practices. High concentrations of dissolved oxygen (less than 0.1 to 8.2 milligrams per liter) in the surficial aquifer system underlying the Ocala National Forest indicate that the aquifer is readily recharged by precipitation and is susceptible to surface contamination. Concentrations of total dissolved solids were significantly greater in the Upper Floridan aquifer (median was 182 milligrams per liter) than in the surficial aquifer system. In general, water quality of the Upper Floridan aquifer was homogeneous, primarily being a calcium or calciummagnesium- bicarbonate water type. Near the St. Johns River, the water type of the Upper Floridan aquifer is sodium-chloride, corresponding to an increase in total dissolved

Characterising aquifer treatment for pathogens in managed aquifer recharge.

Science.gov (United States)

Page, D; Dillon, P; Toze, S; Sidhu, J P S

2010-01-01

In this study the value of subsurface treatment of urban stormwater during Aquifer Storage Transfer Recovery (ASTR) is characterised using quantitative microbial risk assessment (QMRA) methodology. The ASTR project utilizes a multi-barrier treatment train to treat urban stormwater but to date the role of the aquifer has not been quantified. In this study it was estimated that the aquifer barrier provided 1.4, 2.6, >6.0 log(10) removals for rotavirus, Cryptosporidium and Campylobacter respectively based on pathogen diffusion chamber results. The aquifer treatment barrier was found to vary in importance vis-à-vis the pre-treatment via a constructed wetland and potential post-treatment options of UV-disinfection and chlorination for the reference pathogens. The risk assessment demonstrated that the human health risk associated with potable reuse of stormwater can be mitigated (disability adjusted life years, DALYs aquifer is integrated with suitable post treatment options into a treatment train to attenuate pathogens and protect human health.

Modeling the potential impact of seasonal and inactive multi-aquifer wells on contaminant movement to public water-supply wells

Science.gov (United States)

Johnson, R.L.; Clark, B.R.; Landon, M.K.; Kauffman, L.J.; Eberts, S.M.

2011-01-01

Wells screened across multiple aquifers can provide pathways for the movement of surprisingly large volumes of groundwater to confined aquifers used for public water supply (PWS). Using a simple numerical model, we examine the impact of several pumping scenarios on leakage from an unconfined aquifer to a confined aquifer and conclude that a single inactive multi-aquifer well can contribute nearly 10% of total PWS well flow over a wide range of pumping rates. This leakage can occur even when the multi-aquifer well is more than a kilometer from the PWS well. The contribution from multi-aquifer wells may be greater under conditions where seasonal pumping (e.g., irrigation) creates large, widespread downward hydraulic gradients between aquifers. Under those conditions, water can continue to leak down a multi-aquifer well from an unconfined aquifer to a confined aquifer even when those multi-aquifer wells are actively pumped. An important implication is that, if an unconfined aquifer is contaminated, multi-aquifer wells can increase the vulnerability of a confined-aquifer PWS well.

Alluvial Aquifer

Data.gov (United States)

Kansas Data Access and Support Center — This coverage shows the extents of the alluvial aquifers in Kansas. The alluvial aquifers consist of unconsolidated Quaternary alluvium and contiguous terrace...

Laboratory evidence of MTBE biodegradation in Borden aquifer material

Science.gov (United States)

Schirmer, Mario; Butler, Barbara J.; Church, Clinton D.; Barker, James F.; Nadarajah, Nalina

2003-02-01

Mainly due to intrinsic biodegradation, monitored natural attenuation can be an effective and inexpensive remediation strategy at petroleum release sites. However, gasoline additives such as methyl tert-butyl ether (MTBE) can jeopardize this strategy because these compounds often degrade, if at all, at a slower rate than the collectively benzene, toluene, ethylbenzene and the xylene (BTEX) compounds. Investigation of whether a compound degrades under certain conditions, and at what rate, is therefore important to the assessment of the intrinsic remediation potential of aquifers. A natural gradient experiment with dissolved MTBE-containing gasoline in the shallow, aerobic sand aquifer at Canadian Forces Base (CFB) Borden (Ontario, Canada) from 1988 to 1996 suggested that biodegradation was the main cause of attenuation for MTBE within the aquifer. This laboratory study demonstrates biologically catalyzed MTBE degradation in Borden aquifer-like environments, and so supports the idea that attenuation due to biodegradation may have occurred in the natural gradient experiment. In an experiment with batch microcosms of aquifer material, three of the microcosms ultimately degraded MTBE to below detection, although this required more than 189 days (or >300 days in one case). Failure to detect the daughter product tert-butyl alcohol (TBA) in the field and the batch experiments could be because TBA was more readily degradable than MTBE under Borden conditions.

Bedrock aquifers of eastern San Juan County, Utah

Science.gov (United States)

Avery, Charles

1986-01-01

This study is one of a series of studies appraising the waterbearing properties of the Navajo Sandstone and associated formations in southern Utah.  The study area is about 4,600 square miles, extending from the Utah-Arizona State line northward to the San Juan-Grand County line and westward from the Utah-Colorado State line to the longitude of about 109°50'.Some of the water-yielding formations are grouped into aquifer systems. The C aquifer is comprised of the DeChelly Sandstone Member of the Cutler Formation.  The P aquifer is comprised of the Cedar Mesa Member of the Cutler Formation and the undifferentiated Cutler Formation. The N aquifer is comprised of the sedimentary section that includes the Wingate Sandstone, Kayenta Formation, Navajo Sandstone, Carmel Formation, and Entrada sandstone.  The M aquifer is comprised of the Bluff Sandstone Member and other sandstone units of the Morrison Formation.  The D aquifer is comprised of the Burro Canyon Formation and Dakota Sandstone.  Discharge from the ground-water reservoir to the San Juan River between gaging stations at Four Corners and Mexican Hat is about 66 cubic feet per second.The N aquifer is the main aquifer in the study area. Recharge by infiltration of precipitation is estimated to be 25,000 acre-feet per year.  A major ground-water divide exists under the broad area east of Monticello.  The thickness of the N aquifer, where the sedimentary section is fully preserved and saturated, generally is 750 to 1,250 feet.   Hydraulic conductivity values obtained from aquifer tests range from 0.02 to 0.34 foot per day.  The total volume of water in transient storage is about 11 million acre-feet. Well discharge somewhat exceeded 2,340 acre-feet during 1981.  Discharge to the San Juan River from the N aquifer is estimated to be 6.9 cubic feet per second. Water quality ranges from a calcium bicarbonate to sodium chloride type water

Hydrochemical processes in a shallow coal seam gas aquifer and its overlying stream–alluvial system: implications for recharge and inter-aquifer connectivity

International Nuclear Information System (INIS)

Duvert, Clément; Raiber, Matthias; Owen, Daniel D.R.; Cendón, Dioni I.; Batiot-Guilhe, Christelle; Cox, Malcolm E.

2015-01-01

Highlights: • Major ions and isotopes used to study inter-aquifer mixing in a shallow CSG setting. • Considerable heterogeneity in the water composition of the coal-bearing aquifer. • Rapid recharge of the coal-bearing aquifer through highly fractured igneous rocks. • Potential mixing between the coal-bearing aquifer and downstream alluvial aquifer. • Need to consider the seasonal influences on inter-aquifer mixing in CSG settings. - Abstract: In areas of potential coal seam gas (CSG) development, understanding interactions between coal-bearing strata and adjacent aquifers and streams is of highest importance, particularly where CSG formations occur at shallow depth. This study tests a combination of hydrochemical and isotopic tracers to investigate the transient nature of hydrochemical processes, inter-aquifer mixing and recharge in a catchment where the coal-bearing aquifer is in direct contact with the alluvial aquifer and surface drainage network. A strong connection was observed between the main stream and underlying alluvium, marked by a similar evolution from fresh Ca–Mg–HCO 3 waters in the headwaters towards brackish Ca–Na–Cl composition near the outlet of the catchment, driven by evaporation and transpiration. In the coal-bearing aquifer, by contrast, considerable site-to-site variations were observed, although waters generally had a Na–HCO 3 –Cl facies and high residual alkalinity values. Increased salinity was controlled by several coexisting processes, including transpiration by plants, mineral weathering and possibly degradation of coal organic matter. Longer residence times and relatively enriched carbon isotopic signatures of the downstream alluvial waters were suggestive of potential interactions with the shallow coal-bearing aquifer. The examination of temporal variations in deuterium excess enabled detection of rapid recharge of the coal-bearing aquifer through highly fractured igneous rocks, particularly at the catchment

Vertical variability of arsenic concentrations under the control of iron-sulfur-arsenic interactions in reducing aquifer systems

Science.gov (United States)

Pi, Kunfu; Wang, Yanxin; Postma, Dieke; Ma, Teng; Su, Chunli; Xie, Xianjun

2018-06-01

High spatial variability of arsenic (As) concentration in geogenic As-contaminated groundwater has been commonly observed worldwide, but the underlying reasons remain not well understood. Selecting a sulfate-containing, As-affected aquifer at the Datong Basin, northern China as the study area and combining hydrogeochemical investigation and sediment extraction with reactive transport modeling, this work elucidated the roles of Fe-S-As interactions in regulating the vertical variation of As concentration in the groundwater. Dissolved As concentration varied between 0.05 and 18 μmol/L, but generally increased in the depth of 20-25 m and then decreased in 25-30 m. The high-As groundwater contained low Fe(II) (groundwater devoid of sulfate reduction. The reductive dissolution of As-bearing Fe(III) oxides coupled to the degradation of organic matter with an estimated maximum rate of 0.22 mmol C/L/yr, mainly accounted for the depth-dependent increase of As concentration in the upper part of the shallow aquifer (groundwater but also probably co-precipitated As to prompt As decrease in the depth of 25-30 m. Arsenite adsorbed on remaining Fe(III) oxides and newly-formed Fe(II) sulfides is another important pool of As in the aquifer, which varies in response to the extents of Fe(III)-oxide and sulfate reduction and consequently alters As distribution coefficient between the solid and the aqueous phases. This study highlights the importance of coupled geochemical cycling of Fe, S and As for As mobilization and reveals how it regulates As partitioning between groundwater and sediments.

Discourse characteristics of ore-bearing aquifer of Chaidenghao in Husiliang area

International Nuclear Information System (INIS)

Zhou Bowen

2012-01-01

Call Sri Lanka article focuses primarily on wood board beam region trench features lots of ore-bearing aquifer, located in the ore-bearing aquifer under Zhiluo lower sub-section; A brief introduction to the work area's geology and stratigraphic structure, and a brief description of the main ore purpose of the lower layer Zhiluo under sub-section lithology; Shows aquifer top, bottom and described its characteristics, the two formed a 'watertight-water-impermeable' good hydrogeological structure of the ancient interlayer oxidation zone formation to create a favorable space. Based on the above description and analysis of the location of uranium mineralization in good condition, have a good vision of the mineralization. (author)

Quantification of the impacts of coalmine water irrigation on the underlying aquifers

Energy Technology Data Exchange (ETDEWEB)

Vermeulen, D.; Usher, B.; van Tonder, G. [University of Free State, Bloemfontein (South Africa). Institute of Groundwater Studies

2009-07-15

It is predicted that vast volumes of affected mine water will be produced by mining activities in the Mpumalanga coalfields of South Africa, The potential environmental impact of this excess water is of great concern in a water-scarce country like South Africa. Research over a period of more than 10 years has shown that this water can be used successfully for the irrigation of a range of crops. There is, however, continuing concern from the local regulators regarding the long-term impact that large-scale mine water irrigation may have on groundwater quality and quantity. Detailed research has been undertaken over the last three years to supplement the groundwater monitoring programme at five different pilot sites, on both virgin soils (greenfields) and in coalmining spoils. These sites range from sandy soils to very clayey soils. The research has included soil moisture measurements, collection of in situ soil moisture over time, long-term laboratory studies of the leaching and attenuation properties of different soils and the impact of irrigation on acid rock drainage processes, and in depth determination of the hydraulic properties of the subsurface at each of these sites, including falling head tests, pumping tests and point dilution tests. This has been supported by geochemical modelling of these processes to quantify the impacts. The results indicate that many of the soils have considerable attenuation capacities and that in the period of irrigation, a large proportion of the salts have been contained in the upper portions of the unsaturated zones below each irrigation pivot. The volumes and quality of water leaching through to the aquifers have been quantified at each site. From this mixing ratios have been calculated in order to determine the effect of the irrigation water on the underlying aquifers.

Nitrate Leaching under Vegetable Fields above a Shallow Aquifer in Slovenia

International Nuclear Information System (INIS)

Zupanc, V.; Sturm, M.; Lojen, S.; Marsic-Kacjana, N.; Pintar, M.; Adu-Gyamfi, J.; Bracic-Zeleznik, B.; Urbanc, J.

2012-01-01

Shallow aquifers can be prone to nitrate pollution, especially in rural, high rainfall zones under intensive vegetable production, as well as in areas with urban and industrial pollution. Due to its mobility in the soil, nitrate is the most problematic pollutant in intensive agricultural production areas. The risk of nitrate leaching is closely related to the excessive application of organic and inorganic nitrogen (N) fertilizers and can occur at and after harvest, as well as during the crop cycle, because of excessive irrigation or heavy precipitation. The impact of agriculture on groundwater quality can be minimized through improved nitrogen and water management (irrigation) practices, which should be evaluated with regard to their production, polluting effects and cost effectiveness. Most of the Slovenian highly fertile arable lands occur on plains in the shallow groundwater recharge zones, and are used for intensive fresh vegetable production, an important source of income generation for the farmers. These shallow alluvial aquifers are, however, one of the country's most important sources of drinking water. This leads to a conflict of interest between drinking water resource protection and agricultural production. The common farming practice in Slovenia is to broadcast fertilizer applications which often results in extensive nitrate leaching. Thus nitrate management in agriculture is a contentious issue, as adequate nitrogen fertilization is required to ensure reasonable crop yields, yet excessive N fertilization can lead to groundwater pollution. Through an IAEA technical cooperation project SLO 5002 Protecting Groundwater and Soil Pollutants using Nuclear echniques, various irrigation, nitrogen and cropping system management strategies for the production of vegetables with a shorter growing period were assessed at a benchmark site in Slovenia during the years 2006 and 2007. Four irrigation and fertilization treatments were applied: (1) 50% drip irrigation of

Comparison of aquifer characteristics derived from local and regional aquifer tests.

Science.gov (United States)

Randolph, R.B.; Krause, R.E.; Maslia, M.L.

1985-01-01

A comparison of the aquifer parameter values obtained through the analysis of a local and a regional aquifer test involving the same area in southeast Georgia is made in order to evaluate the validity of extrapolating local aquifer-test results for use in large-scale flow simulations. Time-drawdown and time-recovery data were analyzed by using both graphical and least-squares fitting of the data to the Theis curve. Additionally, directional transmissivity, transmissivity tensor, and angle of anisotropy were computed for both tests. -from Authors Georgia drawdown transmissivity regional aquifer tests

Aquifer Storage Recovery (ASR) of chlorinated municipal drinking water in a confined aquifer

Science.gov (United States)

Izbicki, John A.; Petersen, Christen E.; Glotzbach, Kenneth J.; Metzger, Loren F.; Christensen, Allen H.; Smith, Gregory A.; O'Leary, David R.; Fram, Miranda S.; Joseph, Trevor; Shannon, Heather

2010-01-01

About 1.02 x 106 m3 of chlorinated municipal drinking water was injected into a confined aquifer, 94-137 m below Roseville, California, between December 2005 and April 2006. The water was stored in the aquifer for 438 days, and 2.64 x 106 m3 of water were extracted between July 2007 and February 2008. On the basis of Cl data, 35% of the injected water was recovered and 65% of the injected water and associated disinfection by-products (DBPs) remained in the aquifer at the end of extraction. About 46.3 kg of total trihalomethanes (TTHM) entered the aquifer with the injected water and 37.6 kg of TTHM were extracted. As much as 44 kg of TTHMs remained in the aquifer at the end of extraction because of incomplete recovery of injected water and formation of THMs within the aquifer by reactions with freechlorine in the injected water. Well-bore velocity log data collected from the Aquifer Storage Recovery (ASR) well show as much as 60% of the injected water entered the aquifer through a 9 m thick, high-permeability layer within the confined aquifer near the top of the screened interval. Model simulations of ground-water flow near the ASR well indicate that (1) aquifer heterogeneity allowed injected water to move rapidly through the aquifer to nearby monitoring wells, (2) aquifer heterogeneity caused injected water to move further than expected assuming uniform aquifer properties, and (3) physical clogging of high-permeability layers is the probable cause for the observed change in the distribution of borehole flow. Aquifer heterogeneity also enhanced mixing of native anoxic ground water with oxic injected water, promoting removal of THMs primarily through sorption. A 3 to 4-fold reduction in TTHM concentrations was observed in the furthest monitoring well 427 m downgradient from the ASR well, and similar magnitude reductions were observed in depth-dependent water samples collected from the upper part of the screened interval in the ASR well near the end of the extraction

National Uranium Resource Evaluation: Lamar quadrangle, Colorado and Kansas

International Nuclear Information System (INIS)

Maarouf, A.M.; Johnson, V.C.

1982-01-01

Uranium resources of the Lamar Quadrangle, Colorado and Kansas, were evaluated using National Uranium Resource Evaluation criteria. The environment favorable for uranium is the Lower Cretaceous Dakota Sandstone in the area east of John Martin Reservoir for south Texas roll-type sandstone deposits. Carbonaceous trash and sulfides are abundant in the Dakota Sandstone. The unit underlies a thick Upper Cretaceous section that contains bentonitic beds and uraniferous marine black shale. Water samples from the Dakota Sandstone aquifer contain as much as 122 ppB U 3 O 8 . Geologic units considered unfavorable include most of the Paleozoic rocks, except in the Brandon Fault area; the Upper Cretaceous rocks; and the Ogallala Formation. The Dockum Group, Morrison Formation, and Lytle Member of the Purgatoire Formation are unevaluated because of lack of data

Neogene and Quaternary foraminifera and paleoenvironments of a corehole from Horn Island, Mississippi

Science.gov (United States)

Gibson, Thomas G.

1994-01-01

The only semipermanent surface water available on the Southern High Plains plateau of Texas and New Mexico is contained in saline lakes and in the playa lakes that form in shallow depressions, called playa basins, following heavy rainfall. The playas generally are accepted as the main source of recharge to the underlying High Plains (Ogallala) aquifer of the region, and they constitute the major wildlife habitat on the Southern High Plains. Their use as water sources, holding ponds, and waste-disposal sites by agricultural and industrial operations may potentially lead to ground-water contamination and habitat degradation. Therefore, playa lakes will play an essential role in the collection of surface-water quality and ecological data for the Southern High Plains study unit of the National Water-Quality Assessment program of the U.S. Geological Survey.

Semianalytical solutions for contaminant transport under variable velocity field in a coastal aquifer

Science.gov (United States)

Koohbor, Behshad; Fahs, Marwan; Ataie-Ashtiani, Behzad; Simmons, Craig T.; Younes, Anis

2018-05-01

Existing closed-form solutions of contaminant transport problems are limited by the mathematically convenient assumption of uniform flow. These solutions cannot be used to investigate contaminant transport in coastal aquifers where seawater intrusion induces a variable velocity field. An adaptation of the Fourier-Galerkin method is introduced to obtain semi-analytical solutions for contaminant transport in a confined coastal aquifer in which the saltwater wedge is in equilibrium with a freshwater discharge flow. Two scenarios dealing with contaminant leakage from the aquifer top surface and contaminant migration from a source at the landward boundary are considered. Robust implementation of the Fourier-Galerkin method is developed to efficiently solve the coupled flow, salt and contaminant transport equations. Various illustrative examples are generated and the semi-analytical solutions are compared against an in-house numerical code. The Fourier series are used to evaluate relevant metrics characterizing contaminant transport such as the discharge flux to the sea, amount of contaminant persisting in the groundwater and solute flux from the source. These metrics represent quantitative data for numerical code validation and are relevant to understand the effect of seawater intrusion on contaminant transport. It is observed that, for the surface contamination scenario, seawater intrusion limits the spread of the contaminant but intensifies the contaminant discharge to the sea. For the landward contamination scenario, moderate seawater intrusion affects only the spatial distribution of the contaminant plume while extreme seawater intrusion can increase the contaminant discharge to the sea. The developed semi-analytical solution presents an efficient tool for the verification of numerical models. It provides a clear interpretation of the contaminant transport processes in coastal aquifers subject to seawater intrusion. For practical usage in further studies, the full

An analytical solution for modeling thermal energy transfer in a confined aquifer system

Science.gov (United States)

Shaw-Yang, Yang; Hund-der, Yeh

2008-12-01

A mathematical model is developed for simulating the thermal energy transfer in a confined aquifer with different geological properties in the underlying and overlying rocks. The solutions for temperature distributions in the aquifer, underlying rock, and overlying rock are derived by the Laplace transforms and their corresponding time-domain solutions are evaluated by the modified Crump method. Field data adopted from the literature are used as examples to demonstrate the applicability of the solutions in modeling the heat transfer in an aquifer thermal energy storage (ATES) system. The results show that the aquifer temperature increases with time, injection flow rate, and water temperature. However, the temperature decreases with increasing radial and vertical distances. The heat transfer in the rocks is slow and has an effect on the aquifer temperature only after a long period of injection time. The influence distance depends on the aquifer physical and thermal properties, injection flow rate, and injected water temperature. A larger value of thermal diffusivity or injection flow rate will result in a longer influence distance. The present solution can be used as a tool for designing the heat injection facilities for an ATES system.

Estimated hydrologic budgets of kettle-hole ponds in coastal aquifers of southeastern Massachusetts

Science.gov (United States)

Walter, Donald A.; Masterson, John P.

2011-01-01

Kettle-hole ponds in southeastern Massachusetts are in good hydraulic connection to an extensive coastal aquifer system that includes the Plymouth-Carver aquifer system on the mainland and aquifers underlying Cape Cod. The ponds receive water from, and contribute water to, the underlying glacial aquifer; ponds also receive water from precipitation and lose water to evaporation from the pond surface. Some ponds are connected to surface-water drainage systems and receive water from or contribute water to streams or adjacent wetlands. The Massachusetts Department of Environmental Protection currently (2011) is developing Total Maximum Daily Loads of phosphorus for the freshwater ponds in the region to maintain the health of pond ecosystems; the amounts and sources of water fluxes into and out of the ponds are important factors in determining the amount of phosphorus that can be assimilated into a pond. To assist in this effort, the U.S. Geological Survey used groundwater-flow models of the coastal aquifer system to estimate hydrologic budgets-including inflows and outflows from the aquifer system and adjacent streams and wetlands, and recharge from precipitation-for 425 ponds in southeastern Massachusetts.

An evaluation of aquifer intercommunication between the unconfined and Rattlesnake Ridge aquifers on the Hanford Site

International Nuclear Information System (INIS)

Jensen, E.J.

1987-10-01

During 1986, Pacific Northwest Laboratory conducted a study of a portion of the Rattlesnake Ridge aquifer (confined aquifer) that lies beneath the B Pond - Gable Mountain Pond area of the Hanford Site. The purpose was to determine the extent of intercommunication between the unconfined aquifer and the uppermost regionally extensive confined aquifer, referred to as the Rattlesnake Ridge aquifer. Hydraulic head data and chemical data were collected from the ground water in the study area during December 1986. The hydraulic head data were used to determine the effects caused by water discharged to the ground from B Pond on both the water table of the unconfined aquifer and the potentiometric surface of the confined aquifer. The chemical data were collected to determine the extent of chemical constituents migrating from the unconfined aquifer to the confined aquifer. Analysis of chemical constituents in the Rattlesnake Ridge aquifer demonstrated that communication between the unconfined and confined aquifers had occurred. However, the levels of contaminants found in the Rattlesnake Ridge aquifer during this study were below the DOE Derived Concentration Guides

Diagnosis of the Ghiss Nekor aquifer in order to elaborate the aquifer contract

Science.gov (United States)

Baite, Wissal; Boukdir, A.; Zitouni, A.; Dahbi, S. D.; Mesmoudi, H.; Elissami, A.; Sabri, E.; Ikhmerdi, H.

2018-05-01

The Ghiss-Nekor aquifer, located in the north-east of the action area of the ABHL, plays a strategic role in the drinkable water supply of the city of Al Hoceima and of the neighboring urban areas. It also participates in the irrigation of PMH. However, this aquifer has problems such as over-exploitation and pollution. In the face of these problems, the only Solution is the establishment of a new mode of governance, which privileges the participation, the involvement and the responsibility of the actors concerned in a negotiated contractual framework, namely the aquifer contract. The purpose of this study is to diagnose the current state of the Ghiss Nekor aquifer, the hydrogeological characterization of the aquifer, the use of the waters of the aquifer, the Problem identification and the introduction of the aquifer contract, which aims at the participatory and sustainable management of underground water resources in the Ghiss- Nekor plain, to ensure sustainable development.

Aquifer thermal energy storage. International symposium: Proceedings

Energy Technology Data Exchange (ETDEWEB)

NONE

1995-05-01

Aquifers have been used to store large quantities of thermal energy to supply process cooling, space cooling, space heating, and ventilation air preheating, and can be used with or without heat pumps. Aquifers are used as energy sinks and sources when supply and demand for energy do not coincide. Aquifer thermal energy storage may be used on a short-term or long-term basis; as the sole source of energy or as a partial storage; at a temperature useful for direct application or needing upgrade. The sources of energy used for aquifer storage are ambient air, usually cold winter air; waste or by-product energy; and renewable energy such as solar. The present technical, financial and environmental status of ATES is promising. Numerous projects are operating and under development in several countries. These projects are listed and results from Canada and elsewhere are used to illustrate the present status of ATES. Technical obstacles have been addressed and have largely been overcome. Cold storage in aquifers can be seen as a standard design option in the near future as it presently is in some countries. The cost-effectiveness of aquifer thermal energy storage is based on the capital cost avoidance of conventional chilling equipment and energy savings. ATES is one of many developments in energy efficient building technology and its success depends on relating it to important building market and environmental trends. This paper attempts to provide guidance for the future implementation of ATES. Individual projects have been processed separately for entry onto the Department of Energy databases.

Distribution of aquifers, liquid-waste impoundments, and municipal water-supply sources, Massachusetts

Science.gov (United States)

Delaney, David F.; Maevsky, Anthony

1980-01-01

Impoundments of liquid waste are potential sources of ground-water contamination in Massachusetts. The map report, at a scale of 1 inch equals 4 miles, shows the idstribution of aquifers and the locations of municipal water-supply sources and known liquid-waste impoundments. Ground water, an important source of municipal water supply, is produced from shallow sand and gravel aquifers that are generally unconfined, less than 200 feet thick, and yield less than 2,000 gallons per minute to individual wells. These aquifers commonly occupy lowlands and stream valleys and are most extensive in eastern Massachusetts. Surface impoundments of liquid waste are commonly located over these aquifers. These impoundments may leak and allow waste to infiltrate underlying aquifers and alter their water quality. (USGS)

Identification of the microbes mediating Fe reduction in a deep saline aquifer and their influence during managed aquifer recharge.

Science.gov (United States)

Ko, Myoung-Soo; Cho, Kyungjin; Jeong, Dawoon; Lee, Seunghak

2016-03-01

In this study, indigenous microbes enabling Fe reduction under saline groundwater conditions were identified, and their potential contribution to Fe release from aquifer sediments during managed aquifer recharge (MAR) was evaluated. Sediment and groundwater samples were collected from a MAR feasibility test site in Korea, where adjacent river water will be injected into the confined aquifer. The residual groundwater had a high salinity over 26.0 psu, as well as strong reducing conditions (dissolved oxygen, DOaquifer were found to be Citrobacter sp. However, column experiments to simulate field operation scenarios indicated that additional Fe release would be limited during MAR, as the dominant microbial community in the sediment would shift from Citrobacter sp. to Pseudomonas sp. and Limnohabitans sp. as river water injection alters the pore water chemistry. Copyright © 2015 Elsevier B.V. All rights reserved.

Solute geochemistry of the Snake River Plain regional aquifer system, Idaho and eastern Oregon

International Nuclear Information System (INIS)

Wood, W.W.; Low, W.H.

1987-01-01

Three geochemical methods were used to determine chemical reactions that control solute concentrations in the Snake River Plain regional aquifer system: (1) calculation of a regional solute balance within the aquifer and of mineralogy in the aquifer framework to identify solute reactions, (2) comparison of thermodynamic mineral saturation indices with plausible solute reactions, and (3) comparison of stable isotope ratios of the groundwater with those in the aquifer framework. The geothermal groundwater system underlying the main aquifer system was examined by calculating thermodynamic mineral saturation indices, stable isotope ratios of geothermal water, geothermometry, and radiocarbon dating. Water budgets, hydrologic arguments, and isotopic analyses for the eastern Snake River Plain aquifer system demonstrate that most, if not all, water is of local meteoric and not juvenile or formation origin. Solute balance, isotopic, mineralogic, and thermodynamic arguments suggest that about 20% of the solutes are derived from reactions with rocks forming the aquifer framework. Reactions controlling solutes in the western Snake river basin are believed to be similar to those in the eastern basin but the regional geothermal system that underlies the Snake river Plain contains total dissolved solids similar to those in the overlying Snake River Plain aquifer system but contains higher concentrations of sodium, bicarbonate, silica, fluoride, sulfate, chloride, arsenic, boron, and lithium, and lower concentrations of calcium, magnesium, and hydrogen. 132 refs., 30 figs., 27 tabs

The origin of groundwater composition in the Pampeano Aquifer underlying the Del Azul Creek basin, Argentina

International Nuclear Information System (INIS)

Zabala, M.E.; Manzano, M.; Vives, L.

2015-01-01

The Pampean plain is the most productive region in Argentina. The Pampeano Aquifer beneath the Pampean plain is used mostly for drinking water. The study area is the sector of the Pampeano Aquifer underlying the Del Azul Creek basin, in Buenos Aires province. The main objective is to characterize the chemical and isotopic compositions of groundwater and their origin on a regional scale. The methodology used involved the identification and characterization of potential sources of solutes, the study of rain water and groundwater chemical and isotopic characteristics to deduce processes, the development of a hydrogeochemical conceptual model, and its validation by hydrogeochemical modelling with PHREEQC. Groundwater samples come mostly from a two-depth monitoring network of the “Dr. Eduardo J. Usunoff” Large Plains Hydrology Institute (IHLLA). Groundwater salinity increases from SW to NE, where groundwater is saline. In the upper basin groundwater is of the HCO 3 -Ca type, in the middle basin it is HCO 3 -Na, and in the lower basin it is ClSO 4 –NaCa and Cl–Na. The main processes incorporating solutes to groundwater during recharge in the upper basin are rain water evaporation, dissolution of CO 2 , calcite, dolomite, silica, and anorthite; cationic exchange with Na release and Ca and Mg uptake, and clay precipitation. The main processes modifying groundwater chemistry along horizontal flow at 30 m depth from the upper to the lower basin are cationic exchange, dissolution of silica and anorthite, and clay precipitation. The origin of salinity in the middle and lower basin is secular evaporation in a naturally endorheic area. In the upper and middle basins there is agricultural pollution. In the lower basin the main pollution source is human liquid and solid wastes. Vertical infiltration through the boreholes annular space during the yearly flooding stages is probably the pollution mechanism of the samples at 30 m depth. - Highlights: • The work studies the

The origin of groundwater composition in the Pampeano Aquifer underlying the Del Azul Creek basin, Argentina

Energy Technology Data Exchange (ETDEWEB)

Zabala, M.E., E-mail: mzabala@faa.unicen.edu.ar [Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Av. Rivadavia 1917, C1033AAJ Ciudad Autónoma de Buenos Aires (Argentina); Instituto de Hidrología de Llanuras “Dr. Eduardo J. Usunoff”, Av. República Italia 780, 7300 Azul, Provincia Buenos Aires (Argentina); Manzano, M., E-mail: marisol.manzano@upct.es [Escuela de Ingeniería de Caminos, Canales y Puertos y de Ingeniería de Minas, Universidad Politécnica de Cartagena, P° de Alfonso XIII 52, E-30203 Cartagena (Spain); Vives, L., E-mail: lvives@faa.unicen.edu.ar [Instituto de Hidrología de Llanuras “Dr. Eduardo J. Usunoff”, Av. República Italia 780, 7300 Azul, Provincia Buenos Aires (Argentina)

2015-06-15

The Pampean plain is the most productive region in Argentina. The Pampeano Aquifer beneath the Pampean plain is used mostly for drinking water. The study area is the sector of the Pampeano Aquifer underlying the Del Azul Creek basin, in Buenos Aires province. The main objective is to characterize the chemical and isotopic compositions of groundwater and their origin on a regional scale. The methodology used involved the identification and characterization of potential sources of solutes, the study of rain water and groundwater chemical and isotopic characteristics to deduce processes, the development of a hydrogeochemical conceptual model, and its validation by hydrogeochemical modelling with PHREEQC. Groundwater samples come mostly from a two-depth monitoring network of the “Dr. Eduardo J. Usunoff” Large Plains Hydrology Institute (IHLLA). Groundwater salinity increases from SW to NE, where groundwater is saline. In the upper basin groundwater is of the HCO{sub 3}-Ca type, in the middle basin it is HCO{sub 3}-Na, and in the lower basin it is ClSO{sub 4}–NaCa and Cl–Na. The main processes incorporating solutes to groundwater during recharge in the upper basin are rain water evaporation, dissolution of CO{sub 2}, calcite, dolomite, silica, and anorthite; cationic exchange with Na release and Ca and Mg uptake, and clay precipitation. The main processes modifying groundwater chemistry along horizontal flow at 30 m depth from the upper to the lower basin are cationic exchange, dissolution of silica and anorthite, and clay precipitation. The origin of salinity in the middle and lower basin is secular evaporation in a naturally endorheic area. In the upper and middle basins there is agricultural pollution. In the lower basin the main pollution source is human liquid and solid wastes. Vertical infiltration through the boreholes annular space during the yearly flooding stages is probably the pollution mechanism of the samples at 30 m depth. - Highlights: • The

Establishing and testing a catchment water footprint framework to inform sustainable irrigation water use for an aquifer under stress.

Science.gov (United States)

le Roux, Betsie; van der Laan, Michael; Vahrmeijer, Teunis; Bristow, Keith L; Annandale, John G

2017-12-01

Future water scarcities in the face of an increasing population, climate change and the unsustainable use of aquifers will present major challenges to global food production. The ability of water footprints (WFs) to inform water resource management at catchment-scale was investigated on the Steenkoppies Aquifer, South Africa. Yields based on cropping areas were multiplied with season-specific WFs for each crop to determine blue and green water consumption by agriculture. Precipitation and evapotranspiration of natural vegetation and other uses of blue water were included with the agricultural WFs to compare water availability and consumption in a catchment sustainability assessment. This information was used to derive a water balance and develop a catchment WF framework that gave important insights into the hydrology of the aquifer through a simplified method. This method, which requires the monitoring of only a few key variables, including rainfall, agricultural production, WFs of natural vegetation and other blue water flows, can be applied to inform the sustainability of catchment scale water use (as opposed to more complex hydrological studies). Results indicate that current irrigation on the Steenkoppies Aquifer is unsustainable. This is confirmed by declining groundwater levels, and suggests that there should be no further expansion of irrigated agriculture on the Steenkoppies Aquifer. Discrepancies between in- and outflows of water in the catchment indicated that further development of the WF approach is required to improve understanding of the geohydrology of the aquifer and to set and meet sustainability targets for the aquifer. It is envisaged that this 'working' framework can be applied to other water-stressed aquifers around the world. Crown Copyright © 2017. Published by Elsevier B.V. All rights reserved.

EPA Region 1 Sole Source Aquifers

Science.gov (United States)

This coverage contains boundaries of EPA-approved sole source aquifers. Sole source aquifers are defined as an aquifer designated as the sole or principal source of drinking water for a given aquifer service area; that is, an aquifer which is needed to supply 50% or more of the drinking water for the area and for which there are no reasonable alternative sources should the aquifer become contaminated.The aquifers were defined by a EPA hydrogeologist. Aquifer boundaries were then drafted by EPA onto 1:24000 USGS quadrangles. For the coastal sole source aquifers the shoreline as it appeared on the quadrangle was used as a boundary. Delineated boundaries were then digitized into ARC/INFO.

Hydrological connectivity of perched aquifers and regional aquifers in semi-arid environments: a case study from Namibia

Science.gov (United States)

Hamutoko, J. T.; Wanke, H.

2017-12-01

Integrated isotopic and hydrological tracers along with standard hydrological data are used to understand complex dry land hydrological processes on different spatial and temporal scales. The objective of this study is to analyse the relationship between the perched aquifers and the regional aquifer using hydrochemical data and isotopic composition in the Cuvelai-Etosha Basin in Namibia. This relation between the aquifers will aid in understanding groundwater recharge processes and flow dynamics. Perched aquifers are discontinuous shallow aquifers with water level ranging from 0 to 30 meters below ground level. The regional aquifer occurs in semi-consolidated sandstone at depths between about 60 and 160 meters below ground level. Water samples were collected from both aquifers in 10 villages and were analysed for major ions and stable isotopes. The results show overlapping hydrochemistry and isotopic compositions of both aquifers in 8 villages which suggest the possibility of perched aquifer water infiltrating into the regional aquifer. In two villages the hydrochemistry and isotopic composition of the aquifers are totally different and this suggests that there is no interaction between this aquifers. Areas where perched aquifers are connected to regional aquifers maybe recharge zones. These finding have important implications for groundwater resource management.

hydrogeological caracterization and modeling of the aquifer of oued ...

African Journals Online (AJOL)

K. Baba-Hamed

1 janv. 2018 ... Journal of Fundamental and Applied Sciences is licensed under a Creative Commons Attribution-NonCommercial 4.0. International License. Libraries Resource Directory. We are listed under Research Associations category. HYDROGEOLOGICAL CARACTERIZATION AND MODELING OF THE AQUIFER.

Determination of aquifer roof extending under the sea from variable-density flow modelling of groundwater response to tidal loading: case study of the Jahe River Basin, Shandong Province, China

Science.gov (United States)

Cheng, Jianmei; Chen, Chongxi; Ji, Menrui

The main task of studies on salt-water intrusion into coastal confined aquifers is to predict the position of the fresh- salt-water interface, which can be determined from the length of the aquifer roof extending under the sea. Records of groundwater level affected by tides can be used to infer hydrological conditions and determine hydraulic parameters of an aquifer extending under the sea. In this paper, a three-dimensional, variable-density groundwater flow model has been developed to determine the equivalent roof length of an aquifer extending under the sea from the tidal-effected data of groundwater level in the Jahe River Basin, Shandong Province, China. The seaward boundary is obtained by converging hydraulic head fluctuations observed in drill holes with calculated values, and the aquifer parameters in the extending zone are estimated. The impacts of aquifer roof length and aquifer parameters on the fluctuation of tidal groundwater are studied. It is concluded that the length of the aquifer roof extending under the sea should correspond with certain aquifer parameters in the extrapolation zone. Therefore, the seaward boundary determined from tidal-effect information is the equivalent boundary in hydrodynamic characteristics rather than the true boundary of the confined aquifer Les sujets principaux des études d'instrusion saline dans les aquifères confinés en zone côtière sont la prédiction de la position de l'interface entre l'eau salée et l'eau fraîche, qui peut être déterminée à partir de l'extention du toit de l'aquifère sous la mer. Les enregistrements des niveaux des eaux souterraines influencés par les marées peuvent être utilisés pour préciser les conditions hydrologiques et déterminer les paramètres hydrauliques d'un aquifère possédant une extension sous la mer. Dans cet article, un modèle tridimensionnel comprenant des eaux souterraines de densité variable a été développé pour déterminer la longueur équivalente du toit

A Black Hills-Madison Aquifer origin for Dakota Aquifer groundwater in northeastern Nebraska.

Science.gov (United States)

Stotler, Randy; Harvey, F Edwin; Gosselin, David C

2010-01-01

Previous studies of the Dakota Aquifer in South Dakota attributed elevated groundwater sulfate concentrations to Madison Aquifer recharge in the Black Hills with subsequent chemical evolution prior to upward migration into the Dakota Aquifer. This study examines the plausibility of a Madison Aquifer origin for groundwater in northeastern Nebraska. Dakota Aquifer water samples were collected for major ion chemistry and isotopic analysis ((18)O, (2)H, (3)H, (14)C, (13)C, (34)S, (18)O-SO(4), (87)Sr, (37)Cl). Results show that groundwater beneath the eastern, unconfined portion of the study area is distinctly different from groundwater sampled beneath the western, confined portion. In the east, groundwater is calcium-bicarbonate type, with delta(18)O values (-9.6 per thousand to -12.4 per thousand) similar to local, modern precipitation (-7.4 per thousand to -10 per thousand), and tritium values reflecting modern recharge. In the west, groundwater is calcium-sulfate type, having depleted delta(18)O values (-16 per thousand to -18 per thousand) relative to local, modern precipitation, and (14)C ages 32,000 to more than 47,000 years before present. Sulfate, delta(18)O, delta(2)H, delta(34)S, and delta(18)O-SO(4) concentrations are similar to those found in Madison Aquifer groundwater in South Dakota. Thus, it is proposed that Madison Aquifer source water is also present within the Dakota Aquifer beneath northeastern Nebraska. A simple Darcy equation estimate of groundwater velocities and travel times using reported physical parameters from the Madison and Dakota Aquifers suggests such a migration is plausible. However, discrepancies between (14)C and Darcy age estimates indicate that (14)C ages may not accurately reflect aquifer residence time, due to mixtures of varying aged water.

Assessing the Feasibility of Managed Aquifer Recharge for Irrigation under Uncertainty

Directory of Open Access Journals (Sweden)

Muhammad Arshad

2014-09-01

Full Text Available Additional storage of water is a potential option to meet future water supply goals. Financial comparisons are needed to improve decision making about whether to store water in surface reservoirs or below ground, using managed aquifer recharge (MAR. In some places, the results of cost-benefit analysis show that MAR is financially superior to surface storage. However, uncertainty often exists as to whether MAR systems will remain operationally effective and profitable in the future, because the profitability of MAR is dependent on many uncertain technical and financial variables. This paper introduces a method to assess the financial feasibility of MAR under uncertainty. We assess such uncertainties by identification of cross-over points in break-even analysis. Cross-over points are the thresholds where MAR and surface storage have equal financial returns. Such thresholds can be interpreted as a set of minimum requirements beyond which an investment in MAR may no longer be worthwhile. Checking that these thresholds are satisfied can improve confidence in decision making. Our suggested approach can also be used to identify areas that may not be suitable for MAR, thereby avoiding expensive hydrogeological and geophysical investigations.

Estimating Groundwater Mounding in Sloping Aquifers for Managed Aquifer Recharge.

Science.gov (United States)

Zlotnik, Vitaly A; Kacimov, Anvar; Al-Maktoumi, Ali

2017-11-01

Design of managed aquifer recharge (MAR) for augmentation of groundwater resources often lacks detailed data, and simple diagnostic tools for evaluation of the water table in a broad range of parameters are needed. In many large-scale MAR projects, the effect of a regional aquifer base dip cannot be ignored due to the scale of recharge sources (e.g., wadis, streams, reservoirs). However, Hantush's (1967) solution for a horizontal aquifer base is commonly used. To address sloping aquifers, a new closed-form analytical solution for water table mound accounts for the geometry and orientation of recharge sources at the land surface with respect to the aquifer base dip. The solution, based on the Dupiuit-Forchheimer approximation, Green's function method, and coordinate transformations is convenient for computing. This solution reveals important MAR traits in variance with Hantush's solution: mounding is limited in time and space; elevation of the mound is strongly affected by the dip angle; and the peak of the mound moves over time. These findings have important practical implications for assessment of various MAR scenarios, including waterlogging potential and determining proper rates of recharge. Computations are illustrated for several characteristic MAR settings. © 2017, National Ground Water Association.

Transport of Silica Colloid through Saturated Porous Media under Different Hydrogeochemical and Hydrodynamic Conditions Considering Managed Aquifer Recharge

Directory of Open Access Journals (Sweden)

Zhuo Wang

2016-11-01

Full Text Available Colloids may have an important role in regulating the structure and function of groundwater ecosystems, and may influence the migration of low solubility contaminants in groundwater. There is, however, a degree of uncertainty about how colloids behave under the variable hydrogeochemical and hydrodynamic conditions that occur during managed aquifer recharge. We used an online monitoring system to monitor the transport of silica colloid in saturated porous media under different hydrogeochemical conditions, including a range of pH values (5, 7, and 9, ionic strengths (<0.0005, 0.02, and 0.05 M, cation valences (Na+, Ca2+, flow rates (0.1, 0.2, and 0.4 mL/min. The results showed that silica colloid was more likely to deposit on the surface of porous media in acidic conditions (pH = 5 than in alkaline conditions (pH = 9, indicating that the risks of pollution from colloidal interactions would be higher when the pH of the recharge water was higher. Colloid deposition occurred when the ionic strength of the colloidal suspension increased, and bivalent cations had a greater effect than monovalent cations. This suggests that bivalent cation-rich recharge water might affect the porosity of the porous medium because of colloid deposition during the managed aquifer recharge process. As the flow rate increased, the migration ability of silica colloid increased. We simulated the migration of silica colloid in porous media with the COMSOL Multiphysics model.

Biodegradation of phenols in a sandstone aquifer under aerobic conditions and mixed nitrate and iron reducing conditions

DEFF Research Database (Denmark)

Broholm, Mette; Arvin, Erik

2000-01-01

in the groundwater. The potential for biodegradation of the phenols in the sandstone aquifer at the site has been investigated in laboratory microcosms under aerobic (oxygen amended) and mixed nitrate and iron reducing (nitrate enriched and unamended) anaerobic conditions, at a range of concentrations (low: similar...... to 5 mg 1(-1): high: similar to 60 mg 1(-1), and very high: similar to 600 mg 1(-1)) and in the presence of other organic coal-tar compounds (mono- and polyaromatic hydrocarbons (BTEXs and PAHs) and heterocyclic compounds (NSOs)) and ammonia liquor. Sandstone cores and groundwater for the microcosms...

Semi-analytical solution of flow to a well in an unconfined-fractured aquifer system separated by an aquitard

Science.gov (United States)

Sedghi, Mohammad M.; Samani, Nozar; Barry, D. A.

2018-04-01

Semi-analytical solutions are presented for flow to a well in an extensive homogeneous and anisotropic unconfined-fractured aquifer system separated by an aquitard. The pumping well is of infinitesimal radius and screened in either the overlying unconfined aquifer or the underlying fractured aquifer. An existing linearization method was used to determine the watertable drainage. The solution was obtained via Laplace and Hankel transforms, with results calculated by numerical inversion. The main findings are presented in the form of non-dimensional drawdown-time curves, as well as scaled sensitivity-dimensionless time curves. The new solution permits determination of the influence of fractures, matrix blocks and watertable drainage parameters on the aquifer drawdown. The effect of the aquitard on the drawdown response of the overlying unconfined aquifer and the underlying fractured aquifer was also explored. The results permit estimation of the unconfined and fractured aquifer hydraulic parameters via type-curve matching or coupling of the solution with a parameter estimation code. The solution can also be used to determine aquifer hydraulic properties from an optimal pumping test set up and duration.

Aquifer thermal-energy-storage modeling

Science.gov (United States)

Schaetzle, W. J.; Lecroy, J. E.

1982-09-01

A model aquifer was constructed to simulate the operation of a full size aquifer. Instrumentation to evaluate the water flow and thermal energy storage was installed in the system. Numerous runs injecting warm water into a preconditioned uniform aquifer were made. Energy recoveries were evaluated and agree with comparisons of other limited available data. The model aquifer is simulated in a swimming pool, 18 ft by 4 ft, which was filled with sand. Temperature probes were installed in the system. A 2 ft thick aquifer is confined by two layers of polyethylene. Both the aquifer and overburden are sand. Four well configurations are available. The system description and original tests, including energy recovery, are described.

On the migration of uranium isotopes in sandstone aquifers

International Nuclear Information System (INIS)

Froehlich, K.; Gellermann, R.

1982-01-01

Measurements of natural 238 U and 234 U activity in groundwater of sandstone aquifers have been used to study the migration of these uranium isotopes. Regarding the uranium exchange between liquid phase and rock surface during migration, two different models were applied for evaluating the experimental results. Values of corresponding parameters (retardation factor K, removal rate R) reflecting different behaviour concerning this exchange were determined. For example, the values obtained for 238 U in a Triassic sandstone aquifer of the GDR are K = 8.6 x 10 6 and R = 1.3 x 10 -3 a -1 , respectively. It was found that, under the conditions of the sandstone aquifer concerned, the removal rate model is better suited for calculating uranium-isotope migration in groundwater. (author)

A new approach for assessing the future of aquifers supporting irrigated agriculture

Science.gov (United States)

Butler, James J.; Whittemore, Donald O.; Wilson, Blake B.; Bohling, Geoffrey C.

2016-03-01

Aquifers supporting irrigated agriculture are under stress worldwide as a result of large pumping-induced water deficits. To aid in the formulation of more sustainable management plans for such systems, we have developed a water balance approach for assessing the impact of proposed management actions and the prospects for aquifer sustainability. Application to the High Plains aquifer (HPA) in the state of Kansas in the United States reveals that practically achievable reductions in annual pumping (determining the net inflow (capture) component of the water balance. The HPA is similar to many aquifers supporting critically needed agricultural production, so the presented approach should prove of value far beyond the area of this initial application.

Managed Aquifer Recharge Using Treated Wastewater: An Option to Manage a Coastal Aquifer In Oman For Better Domestic Water Supply

Science.gov (United States)

Al-Maktoumi, Ali; Zekri, Slim; ElRawy, Mustafa

2016-04-01

Arid countries, such as the Sultanate of Oman, are facing challenges of water shortages threatening economic development and social stability. Most of those countries are vulnerable to the potential adverse impacts of climate change, the most significant of which are increased average temperatures, less and more erratic precipitation, sea level rise, and desertification. The combined effect of existing adverse conditions and likely impacts of future climate change will make water management even more difficult than what it is today. Tremendous efforts have been devoted to augment the water resources. Managed Aquifer Recharge (MAR) is practiced widely to store water during periods of surpluses and withdraw during deficits from an aquifer. In Muscat, there will be a surplus of >100,000 m3/day of TWW during winter months in the coming few years. The aquifer along the northern coast of Oman (Al-Khawd Aquifer) is conducive for MAR. Data show that TWW volumes will increase from 7.6 Mm3 in 2003 to 70.9 Mm3 in 2035 in Muscat city only. This study assesses, using MODFLOW 2005 numerical code, the impact of MAR using TWW on better management of the Al-Khawd unconfined coastal aquifer for better urban water supply. Specifically, aiming to maximize withdrawals from the domestic wells with minimize adverse effect of seawater intrusion. The model operates under a number of constrains that minimize the loss to the sea and the injected TWW must not migrates upstream (due to developed mound) and reach the wellfields used for domestic supply. The hypothetical injection wells are located downstream the domestic wellfield zone. The results of different managerial scenarios show that MAR produces a hydraulic barrier that decelerates the seawater intrusion which allows higher abstraction of pristine water from the upstream part of the aquifer. MAR along with redistribution/relocation of public wells allows abstraction of 2 times the current abstraction rate (around 6 Mm3/year to 12 Mm3

Estimating energy fluxes within the stream-aquifer interface of the Avenelles basin

Science.gov (United States)

Berrhouma, Asma; Rivière, Agnès; Goblet, Patrick; Cucchi, Karina; Rubin, Yoram; Baudin, Aurélien; Ansart, Patrick; Flipo, Nicolas

2017-04-01

The understanding of water temperature evolution and its associated energy fluxes is important to follow the aquatic habitats evolution and to predict future modifications induced by climate change. The spatio-temporal energy balance dynamics within the stream-aquifer interface is complex because of the multitude of physical, morphological and meteorological parameters on which it depends. This critical interface is involving numerous physical and bio-geochemical processes which are taking place at different time and spatial scales. The energy balance estimation at this interface depends mainly on the direction, magnitude and variability of water exchanges and the temporal variation of river and aquifer temperatures as well as the thermal porous media properties. In this work, a combined numerical and experimental approach is used to study the temporal and spatial evolution of the energy budget along 6 km of the stream network of the Avenelles watershed. With an area of 46 km2, the Avenelles watershed is located 70 km east from Paris. The Avenelles river presents different types of connectivity with the underlying aquifers. Five Local Monitoring Stations (LOMOS) have been deployed along the hydraulic corridor to monitor the water and thermal exchanges between the stream and aquifer over years, based on continuous pressure and temperature measurements in the river, the hyporheic zone (HZ) and the underlying aquifer. A 2D finite element thermo-hydrogeological model (METIS) coupled with a parameters screening script is used to determine the hydrogeological and thermal properties of the HZ and of the underlying aquifers by inversion at five LOMOS. Once the local models are calibrated, water and heat fluxes through the stream - aquifer interface are assessed over years (2012-2015) along the stream network. This work offers a new understanding of the stream-aquifer interface functioning, shifting from a pure hydrological characterizing toward a more subtle view that

Propagation of seasonal temperature signals into an aquifer upon bank infiltration.

Science.gov (United States)

Molina-Giraldo, Nelson; Bayer, Peter; Blum, Philipp; Cirpka, Olaf A

2011-01-01

Infiltrating river water carries the temperature signal of the river into the adjacent aquifer. While the diurnal temperature fluctuations are strongly dampened, the seasonal fluctuations are much less attenuated and can be followed into the aquifer over longer distances. In one-dimensional model with uniform properties, this signal is propagated with a retarded velocity, and its amplitude decreases exponentially with distance. Therefore, time shifts in seasonal temperature signals between rivers and groundwater observation points may be used to estimate infiltration rates and near-river groundwater velocities. As demonstrated in this study, however, the interpretation is nonunique under realistic conditions. We analyze a synthetic test case of a two-dimensional cross section perpendicular to a losing stream, accounting for multi-dimensional flow due to a partially penetrating channel, convective-conductive heat transport within the aquifer, and heat exchange with the underlying aquitard and the land surface. We compare different conceptual simplifications of the domain in order to elaborate on the importance of different system elements. We find that temperature propagation within the shallow aquifer can be highly influenced by conduction through the unsaturated zone and into the underlying aquitard. In contrast, regional groundwater recharge has no major effect on the simulated results. In our setup, multi-dimensionality of the flow field is important only close to the river. We conclude that over-simplistic analytical models can introduce substantial errors if vertical heat exchange at the aquifer boundaries is not accounted for. This has to be considered when using seasonal temperature fluctuations as a natural tracer for bank infiltration. Copyright © 2010 The Author(s). Journal compilation © 2010 National Ground Water Association.

Managed aquifer recharge in weathered crystalline basement aquifers in India: Monitoring of the effect of tank infiltration on water quality over several monsoon events

Science.gov (United States)

Alazard, Marina; Boisson, Alexandre; Maréchal, Jean-Christophe; Dewandel, Benoît; Perrin, Jérôme; Pettenati, Marie; Picot-Colbeaux, Géraldine; Ahmed, Shakeel; Thiéry, Dominique; Kloppmann, Wolfram

2015-04-01

Managed aquifer recharge (MAR) structures like percolation tanks are considered by the Indian national and regional governments as major option for tackling declining groundwater levels due to overexploitation for irrigation purposes (Boisson et al., 2014). Their main purpose is to restore groundwater availability under strong climatic and anthropogenic pressure. Furthermore, MAR-induced dilution with fresh surface water is generally expected to improve groundwater quality with respect to both anthropogenic and geogenic contaminants (total mineralisation, nitrates, chlorides, sulphates and fluoride contents). The impact of a percolation tank on groundwater quality was investigated in a context that is typical for hydro-climatic and geological settings in southern and eastern India: fractured crystalline basement aquifers overlain by a weathering zone under semi-arid climate. Water level data and geochemical indicators (stable isotopes and major ions) were monitored for both groundwater and surface water, over several successive monsoon events. In case of high to very high water levels, the groundwater quality is globally improved. However, in a few cases, the quality of the groundwater can be negatively impacted due to leaching of salts under the tank, particularly during the first rain events of the monsoon. Geogenic fluoride contents in groundwater, induced by water-rock interaction and enhanced by recycling of agricultural return flow under paddy fields, is found to be relatively stable over the year. This finding points out that the underlying processes, mainly dissolution of F-bearing phases like fluorapatites combined with Ca/Na cation exchange and calcite precipitation, both limiting the possibility of F-removal via fluorite precipitation (Pettenati et al., 2013, 2014), are not impacted by the hydrological conditions. This work highlights the complexity of the recharge processes in crystalline aquifers, enhanced by the variability of hydrological conditions

Aquifer test to determine hydraulic properties of the Elm aquifer near Aberdeen, South Dakota

Science.gov (United States)

Schaap, Bryan D.

2000-01-01

The Elm aquifer, which consists of sandy and gravelly glacial-outwash deposits, is present in several counties in northeastern South Dakota. An aquifer test was conducted northeast of Aberdeen during the fall of 1999 to determine the hydraulic properties of the Elm aquifer in that area. An improved understanding of the properties of the aquifer will be useful in the possible development of the aquifer as a water resource. Historical water-level data indicate that the saturated thickness of the Elm aquifer can change considerably over time. From September 1977 through November 1985, water levels at three wells completed in the Elm aquifer near the aquifer test site varied by 5.1 ft, 9.50 ft, and 11.1 ft. From June 1982 through October 1999, water levels at five wells completed in the Elm aquifer near the aquifer test site varied by 8.7 ft, 11.4 ft, 13.2 ft, 13.8 ft, and 19.7 ft. The water levels during the fall of 1999 were among the highest on record, so the aquifer test was affected by portions of the aquifer being saturated that might not be saturated during drier times. The aquifer test was conducted using five existing wells that had been installed prior to this study. Well A, the pumped well, has an operating irrigation pump and is centrally located among the wells. Wells B, C, D, and E are about 70 ft, 1,390 ft, 2,200 ft, and 3,100 ft, respectively, in different directions from Well A. Using vented pressure transducers and programmable data loggers, water-level data were collected at the five wells prior to, during, and after the pumping, which started on November 19, 1999, and continued a little over 72 hours. Based on available drilling logs, the Elm aquifer near the test area was assumed to be unconfined. The Neuman (1974) method theoretical response curves that most closely match the observed water-level changes at Wells A and B were calculated using software (AQTESOLV for Windows Version 2.13-Professional) developed by Glenn M. Duffield of Hydro

Long-term nitrogen behavior under treated wastewater infiltration basins in a soil-aquifer treatment (SAT) system.

Science.gov (United States)

Mienis, Omer; Arye, Gilboa

2018-05-01

The long term behavior of total nitrogen and its components was investigated in a soil aquifer treatment system of the Dan Region Reclamation Project (Shafdan), Tel-Aviv, Israel. Use is made of the previous 40 years' secondary data for the main nitrogen components (ammonium, nitrate and organic nitrogen) in recharged effluent and observation wells located inside an infiltration basin. The wells were drilled to 106 and 67 m, both in a similar position within the basin. The transport characteristics of each nitrogen component were evaluated based on chloride travel-time, calculated by a cross-correlation between its concentration in the recharge effluent and the observation wells. Changes in the source of recharge effluent, wastewater treatment technology and recharge regime were found to be the main factors affecting turnover in total nitrogen and its components. During aerobic operation of the infiltration basins, most organic nitrogen and ammonium will be converted to nitrate. Total nitrogen removal in the upper part of the aquifer was found to be 47-63% by denitrification and absorption, and overall removal, including the lower part of the aquifer, was 49-83%. To maintain the aerobic operation of the infiltration fields, the total nitrogen load should remain below 10 mg/L. Above this limit, ammonium and organic nitrogen will be displaced into the aquifer. Copyright © 2018 Elsevier Ltd. All rights reserved.

Hydrogeological Conditions of a Crystalline Aquifer: Simulation of Optimal Abstraction Rates under Scenarios of Reduced Recharge

Science.gov (United States)

Fynn, Obed Fiifi; Chegbeleh, Larry Pax; Nude, Prosper M.; Asiedu, Daniel K.

2013-01-01

A steady state numerical groundwater flow model has been calibrated to characterize the spatial distribution of a key hydraulic parameter in a crystalline aquifer in southwestern Ghana. This was to provide an initial basis for characterizing the hydrogeology of the terrain with a view to assisting in the large scale development of groundwater resources for various uses. The results suggest that the structural entities that control groundwater occurrence in the area are quite heterogeneous in their nature and orientation, ascribing hydraulic conductivity values in the range of 4.5 m/d to over 70 m/d to the simulated aquifer. Aquifer heterogeneities, coupled possibly with topographical trends, have led to the development of five prominent groundwater flowpaths in the area. Estimated groundwater recharge at calibration ranges between 0.25% and 9.13% of the total annual rainfall and appears to hold significant promise for large-scale groundwater development to support irrigation schemes. However, the model suggests that with reduced recharge by up to 30% of the current rates, the system can only sustain increased groundwater abstraction by up to 150% of the current abstraction rates. Prudent management of the resource will require a much more detailed hydrogeological study that identifies all the aquifers in the basin for the assessment of sustainable basin yield. PMID:24453882

Hydrogeology and water quality of the Floridan aquifer system and effect of Lower Floridan aquifer withdrawals on the Upper Floridan aquifer at Barbour Pointe Community, Chatham County, Georgia, 2013

Science.gov (United States)

Gonthier, Gerard; Clarke, John S.

2016-06-02

Two test wells were completed at the Barbour Pointe community in western Chatham County, near Savannah, Georgia, in 2013 to investigate the potential of using the Lower Floridan aquifer as a source of municipal water supply. One well was completed in the Lower Floridan aquifer at a depth of 1,080 feet (ft) below land surface; the other well was completed in the Upper Floridan aquifer at a depth of 440 ft below land surface. At the Barbour Pointe test site, the U.S. Geological Survey completed electromagnetic (EM) flowmeter surveys, collected and analyzed water samples from discrete depths, and completed a 72-hour aquifer test of the Floridan aquifer system withdrawing from the Lower Floridan aquifer.Based on drill cuttings, geophysical logs, and borehole EM flowmeter surveys collected at the Barbour Pointe test site, the Upper Floridan aquifer extends 369 to 567 ft below land surface, the middle semiconfining unit, separating the two aquifers, extends 567 to 714 ft below land surface, and the Lower Floridan aquifer extends 714 to 1,056 ft below land surface.A borehole EM flowmeter survey indicates that the Upper Floridan and Lower Floridan aquifers each contain four water-bearing zones. The EM flowmeter logs of the test hole open to the entire Floridan aquifer system indicated that the Upper Floridan aquifer contributed 91 percent of the total flow rate of 1,000 gallons per minute; the Lower Floridan aquifer contributed about 8 percent. Based on the transmissivity of the middle semiconfining unit and the Floridan aquifer system, the middle semiconfining unit probably contributed on the order of 1 percent of the total flow.Hydraulic properties of the Upper Floridan and Lower Floridan aquifers were estimated based on results of the EM flowmeter survey and a 72-hour aquifer test completed in Lower Floridan aquifer well 36Q398. The EM flowmeter data were analyzed using an AnalyzeHOLE-generated model to simulate upward borehole flow and determine the transmissivity of

Guarani aquifer hydrogeological synthesis of the Guarani aquifer system. Edicion bilingue

International Nuclear Information System (INIS)

2009-01-01

This work represents the synthesis of current knowledge of the Guarani Aquifer System, based on technical products made by different companies and consultants who participated in the framework of the Project for Environmental Protection and Sustainable Development of the Guarani Aquifer.

Monitoring Aquifer Depletion from Space: Case Studies from the Saharan and Arabian Aquifers

Science.gov (United States)

Ahmed, M.; Sultan, M.; Wahr, J. M.; Yan, E.

2013-12-01

Access to potable fresh water resources is a human right and a basic requirement for economic development in any society. In arid and semi-arid areas, the characterization and understanding of the geologic and hydrologic settings of, and the controlling factors affecting, these resources is gaining increasing importance due to the challenges posed by increasing population. In these areas, there is immense natural fossil fresh water resources stored in large extensive aquifers, the transboundary aquifers. Yet, natural phenomena (e.g., rainfall patterns and climate change) together with human-related factors (e.g., population growth, unsustainable over-exploitation, and pollution) are threatening the sustainability of these resources. In this study, we are developing and applying an integrated cost-effective approach to investigate the nature (i.e., natural and anthropogenic) and the controlling factors affecting the hydrologic settings of the Saharan (i.e., Nubian Sandstone Aquifer System [NSAS], Northwest Sahara Aquifer System [NWSA]) and Arabian (i.e., Arabian Peninsula Aquifer System [APAS]) aquifer systems. Analysis of the Gravity Recovery and Climate Experiment (GRACE)-derived Terrestrial Water Storage (TWS) inter-annual trends over the NSAS and the APAS revealed two areas of significant TWS depletions; the first correlated with the Dakhla Aquifer System (DAS) in the NSAS and second with the Saq Aquifer System (SAS) in the APAS. Annual depletion rates were estimated at 1.3 × 0.66 × 109 m3/yr and 6.95 × 0.68 × 109 m3/yr for DAS and SAS, respectively. Findings include (1) excessive groundwater extraction, not climatic changes, is responsible for the observed TWS depletions ;(2) the DAS could be consumed in 350 years if extraction rates continue to double every 50 years and the APAS available reserves could be consumed within 60-140 years at present extraction (7.08 × 109 m3/yr) and depletion rates; and (3) observed depletions over DAS and SAS and their

Enhancement of wadi recharge using dams coupled with aquifer storage and recovery wells

KAUST Repository

Missimer, Thomas M. M.

2014-06-25

Wadi channel recharge to the underlying alluvial aquifer is naturally limited by the flashy nature of flood events, evapotranspiration losses of water from the vadose zone, and aquifer heterogeneity, particularly low vertical hydraulic conductivity. Anthropogenic lowering of the water table in many wadi aquifers has also reduced the potential recharge by increasing the thickness of the vadose zone, causing interflow water loss from surface emergence and evaporation. A method to enhance recharge is to slow the flow within wadi channels by placement of dam structures, thereby ponding water and increasing the vertical head gradient to create a more rapid rate of infiltration and percolation. Effectiveness of wadi dams to enhance aquifer recharge reduces over time due to mud deposition within the reservoir caused by storm events. Up to 80 % of the water in old wadi reservoirs is lost to free-surface evaporation before infiltration and recharge can occur. One method to maintain or increase the rate of recharge is to convey clean water by gravity flow from the reservoir down-gradient to artificially recharge the aquifer using existing wells. This type of system is a low-cost and low-energy recharge method which could greatly enhance groundwater storage in wadi aquifers. Modeling results show that existing wells could store up to 1,000 m3/day under gravity-feed conditions and up to 3,900 m3/day with the shut-in of the well to produce a pressurized system. © 2014 Springer-Verlag Berlin Heidelberg.

Aquifer thermal energy storage in Finland

Energy Technology Data Exchange (ETDEWEB)

Iihola, H; Ala-Peijari, T; Seppaenen, H

1988-01-01

The rapid changes and crises in the field of energy during the 1970s and 1980s have forced us to examine the use of energy more critically and to look for new ideas. Seasonal aquifer thermal energy storage (T < 100/sup 0/C) on a large scale is one of the grey areas which have not yet been extensively explored. However, projects are currently underway in a dozen countries. In Finland there have been three demonstration projects from 1974 to 1987. International co-operation under the auspices of the International Energy Agency, Annex VI, 'Environmental and Chemical Aspects of Thermal Energy Storage in Aquifers and Research and Development of Water Treatment Methods' started in 1987. The research being undertaken in 8 countries includes several elements fundamental to hydrochemistry and biochemistry.

A General Solution for Groundwater Flow in Estuarine Leaky Aquifer System with Considering Aquifer Anisotropy

Science.gov (United States)

Chen, Po-Chia; Chuang, Mo-Hsiung; Tan, Yih-Chi

2014-05-01

In recent years the urban and industrial developments near the coastal area are rapid and therefore the associated population grows dramatically. More and more water demand for human activities, agriculture irrigation, and aquaculture relies on heavy pumping in coastal area. The decline of groundwater table may result in the problems of seawater intrusion and/or land subsidence. Since the 1950s, numerous studies focused on the effect of tidal fluctuation on the groundwater flow in the coastal area. Many studies concentrated on the developments of one-dimensional (1D) and two-dimensional (2D) analytical solutions describing the tide-induced head fluctuations. For example, Jacob (1950) derived an analytical solution of 1D groundwater flow in a confined aquifer with a boundary condition subject to sinusoidal oscillation. Jiao and Tang (1999) derived a 1D analytical solution of a leaky confined aquifer by considered a constant groundwater head in the overlying unconfined aquifer. Jeng et al. (2002) studied the tidal propagation in a coupled unconfined and confined costal aquifer system. Sun (1997) presented a 2D solution for groundwater response to tidal loading in an estuary. Tang and Jiao (2001) derived a 2D analytical solution in a leaky confined aquifer system near open tidal water. This study aims at developing a general analytical solution describing the head fluctuations in a 2D estuarine aquifer system consisted of an unconfined aquifer, a confined aquifer, and an aquitard between them. Both the confined and unconfined aquifers are considered to be anisotropic. The predicted head fluctuations from this solution will compare with the simulation results from the MODFLOW program. In addition, the solutions mentioned above will be shown to be special cases of the present solution. Some hypothetical cases regarding the head fluctuation in costal aquifers will be made to investigate the dynamic effects of water table fluctuation, hydrogeological conditions, and

Benzene dynamics and biodegradation in alluvial aquifers affected by river fluctuations.

Science.gov (United States)

Batlle-Aguilar, J; Morasch, B; Hunkeler, D; Brouyère, S

2014-01-01

The spatial distribution and temporal dynamics of a benzene plume in an alluvial aquifer strongly affected by river fluctuations was studied. Benzene concentrations, aquifer geochemistry datasets, past river morphology, and benzene degradation rates estimated in situ using stable carbon isotope enrichment were analyzed in concert with aquifer heterogeneity and river fluctuations. Geochemistry data demonstrated that benzene biodegradation was on-going under sulfate reducing conditions. Long-term monitoring of hydraulic heads and characterization of the alluvial aquifer formed the basis of a detailed modeled image of aquifer heterogeneity. Hydraulic conductivity was found to strongly correlate with benzene degradation, indicating that low hydraulic conductivity areas are capable of sustaining benzene anaerobic biodegradation provided the electron acceptor (SO4 (2-) ) does not become rate limiting. Modeling results demonstrated that the groundwater flux direction is reversed on annual basis when the river level rises up to 2 m, thereby forcing the infiltration of oxygenated surface water into the aquifer. The mobilization state of metal trace elements such as Zn, Cd, and As present in the aquifer predominantly depended on the strong potential gradient within the plume. However, infiltration of oxygenated water was found to trigger a change from strongly reducing to oxic conditions near the river, causing mobilization of previously immobile metal species and vice versa. MNA appears to be an appropriate remediation strategy in this type of dynamic environment provided that aquifer characterization and targeted monitoring of redox conditions are adequate and electron acceptors remain available until concentrations of toxic compounds reduce to acceptable levels. © 2013, National Ground Water Association.

Sustainable yield of the Colle Quartara carbonate aquifer in the Southern Lepini Mountains (Central Italy

Directory of Open Access Journals (Sweden)

Giovanni Conte

2016-10-01

Full Text Available The present research is aimed to contribute to the groundwater resource sustainable management of a carbonate aquifer in a test area of the Lepini Mountains (Central Italy. This aquifer constitutes a major exploited groundwater body of central Apennines. At regional scale, the hydrogeological features of the Lepini hydrostructure are well known. The present study focuses on a portion of the Lepini Mountains where important tapping-works for drinking water supply are in activity (about 1.2 m3/s. New investigations were carried out including: meteo-climatic analysis, spring discharge and hydrometric time series processing, pumping test result interpretation. In addition, a detailed lithostratigraphical and structural survey of a portion of the Lepini hydrostructure at 1:10,000 scale was performed also examining the dense network of discontinuities affecting the carbonate aquifer. Extensional Plio-Pleistocene tectonic activity displaced the carbonate rock sequence under the Pontina Plain, where the carbonate aquifer is confined. The investigation results have allowed the reconstruction of the hydrogeological conceptual model of the studied portion of carbonate massif. Given the scale of the study and the results of the investigation, the carbonate aquifer can be treated as an equivalent porous medium, and the simplified numerical model of the aquifer was constructed with the code MODFLOW-2005. The numerical model, still now under continuous implementation, produced first results on the current withdrawal sustainability, allowing evaluation of possible alternative exploitation scenarios of the carbonate aquifer also considering the probably not significant flow exchanges with the Pontina Plain aquifer.

Nutrient Removal during Stormwater Aquifer Storage and Recovery in an Anoxic Carbonate Aquifer.

Science.gov (United States)

Vanderzalm, Joanne L; Page, Declan W; Dillon, Peter J; Barry, Karen E; Gonzalez, Dennis

2018-03-01

Stormwater harvesting coupled to managed aquifer recharge (MAR) provides a means to use the often wasted stormwater resource while also providing protection of the natural and built environment. Aquifers can act as a treatment barrier within a multiple-barrier approach to harvest and use urban stormwater. However, it remains challenging to assess the treatment performance of a MAR scheme due to the heterogeneity of aquifers and MAR operations, which in turn influences water treatment processes. This study uses a probabilistic method to evaluate aquifer treatment performance based on the removal of total organic C (TOC), N, and P during MAR with urban stormwater in an anoxic carbonate aquifer. Total organic C, N, and P are represented as stochastic variables and described by probability density functions (PDFs) for the "injectant" and "recovery"; these injectant and recovery PDFs are used to derive a theoretical MAR removal efficiency PDF. Four long-term MAR sites targeting one of two tertiary carbonate aquifers (T1 and T2) were used to describe the nutrient removal efficiencies. Removal of TOC and total N (TN) was dominated by redox processes, with median removal of TOC between 50 and 60% at all sites and TN from 40 to 50% at three sites with no change at the fourth. Total P removal due to filtration and sorption accounted for median removal of 29 to 53%. Thus, the statistical method was able to characterize the capacity of the anoxic carbonate aquifer treatment barrier for nutrient removal, which highlights that aquifers can be an effective long-term natural treatment option for management of water quality, as well as storage of urban stormwater. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

Onset of density-driven instabilities in fractured aquifers

Science.gov (United States)

Jafari Raad, Seyed Mostafa; Hassanzadeh, Hassan

2018-04-01

Linear stability analysis is conducted to study the onset of density-driven convection involved in solubility trapping of C O2 in fractured aquifers. The effect of physical properties of a fracture network on the stability of a diffusive boundary layer in a saturated fractured porous media is investigated using the dual porosity concept. Linear stability analysis results show that both fracture interporosity flow and fracture storativity play an important role in the stability behavior of the system. It is shown that a diffusive boundary layer under the gravity field in fractured porous media with lower fracture storativity and/or higher fracture interporosity flow coefficient is more stable. We present scaling relations for the onset of convective instability in fractured aquifers with single and variable matrix block size distribution. These findings improve our understanding of density-driven flow in fractured aquifers and are important in the estimation of potential storage capacity, risk assessment, and storage site characterization and screening.

The usefulness of multi-well aquifer tests in heterogeneous aquifers

International Nuclear Information System (INIS)

Young, S.C.; Benton, D.J.; Herweijer, J.C.; Sims, P.

1990-01-01

Three large-scale (100 m) and seven small-scale (3-7 m) multi-well aquifer tests were conducted in a heterogeneous aquifer to determine the transmissivity distribution across a one-hectare test site. Two of the large-scale tests had constant but different rates of discharge; the remaining large-scale test had a discharge that was pulsed at regulated intervals. The small-scale tests were conducted at two well clusters 20 m apart. The program WELTEST was written to analyze the data. By using the methods of non-linear least squares regression analysis and Broyden's method to solve for non-linear extrema, WELTEST automatically determines the best values of transmissivity and the storage coefficient. The test results show that order of magnitude differences in the calculated transmissivities at a well location can be realized by varying the discharge rate at the pumping well, the duration of the aquifer test, and/or the location of the pumping well. The calculated storage coefficients for the tests cover a five-order magnitude range. The data show a definite trend for the storage coefficient to increase with the distance between the pumping and the observation wells. This trend is shown to be related to the orientation of high hydraulic conductivity zones between the pumping and the observation wells. A comparison among single-well aquifer tests, geological investigations and multi-well aquifer tests indicate that the multi-well tests are poorly suited for characterizing a transmissivity field. (Author) (11 refs., 14 figs.)

The Marlborough Deep Wairau Aquifer sustainability review 2008 : isotopic indicators

International Nuclear Information System (INIS)

Morgenstern, U.; van der Raaij, R.W.; Trompetter, V.; McBeth, K.

2008-01-01

The Deep Wairau Aquifer (DWA) consists of several relatively thin water bearing layers at depths generally greater than 150 m separated by thick confining layers and was therefore thought to be relatively isolated from surface hydrological processes, with little pumping induced effects on spring flows and shallow aquifers. However, because the DWA partially underlies fully allocated shallower Southern Valleys Aquifers it is critical to understand the dynamics (recharge, flow) of the DWA. Recent aquifer testing revealed that the DWA is hydraulically linked to the Southern Valley Benmorven Aquifer and that most wells penetrating the DWA are hydraulically linked. The aquifers of the Wairau Plain are formed by a series of glacial and alluvial outwash deposits laid down by the Wairau River. Bore logs indicate that the aquifer contains thin water-bearing layers within the mixed strata. These layers come under artesian pressure towards the east. The Wairau Gravels are overlain by a sequence of glacial outwash and fluvial gravels interspersed with marine deposits. Immediately above the Wairau Gravels lies the Speargrass Formation consisting of poorly sorted glacial outwash gravels, sand and clay deposits. This formation has greater permeability than the Wairau Gravels. Above the Speargrass Formation lie highly permeable postglacial fluvial gravels, sand and silt deposits from the Wairau and tributary rivers known as the Rapaura Formation. Towards the coast, the alluvial gravels are overlain by marine and estuarine deposits of sand, silt and clay known as the Dillons Point Formation. Chemistry and isotope samples were analysed over time from various DWA wells to obtain information on changes in source and age of water with continued abstraction. All DWA water samples are tritium-free indicating that there is no young water influx yet intercepted by any of the sampled wells. Radiocarbon repeat measurements indicate that the water source is changing towards older water with

REDUCTIVE DEHALOGENATION OF A NITROGEN HETEROCYCLIC HERBICIDE IN ANOXIC AQUIFER SLURRIES

Science.gov (United States)

We studied the metabolic fate of bromacil in anaerobic aquifer slurries held under denitrifying, sulfate-reducing, or methanogenic conditions. Liquid chromatograhy-mass spectrometry of the slurries confirmed that bromacil was debrominated under methanogenic conditions but was not...

Closed-form analytical solutions incorporating pumping and tidal effects in various coastal aquifer systems

Science.gov (United States)

Wang, Chaoyue; Li, Hailong; Wan, Li; Wang, Xusheng; Jiang, Xiaowei

2014-07-01

Pumping wells are common in coastal aquifers affected by tides. Here we present analytical solutions of groundwater table or head variations during a constant rate pumping from a single, fully-penetrating well in coastal aquifer systems comprising an unconfined aquifer, a confined aquifer and semi-permeable layer between them. The unconfined aquifer terminates at the coastline (or river bank) and the other two layers extend under tidal water (sea or tidal river) for a certain distance L. Analytical solutions are derived for 11 reasonable combinations of different situations of the L-value (zero, finite, and infinite), of the middle layer's permeability (semi-permeable and impermeable), of the boundary condition at the aquifer's submarine terminal (Dirichlet describing direct connection with seawater and no-flow describing the existence of an impermeable capping), and of the tidal water body (sea and tidal river). Solutions are discussed with application examples in fitting field observations and parameter estimations.

Geochemical Triggers of Arsenic Mobilization during Managed Aquifer Recharge.

Science.gov (United States)

Fakhreddine, Sarah; Dittmar, Jessica; Phipps, Don; Dadakis, Jason; Fendorf, Scott

2015-07-07

Mobilization of arsenic and other trace metal contaminants during managed aquifer recharge (MAR) poses a challenge to maintaining local groundwater quality and to ensuring the viability of aquifer storage and recovery techniques. Arsenic release from sediments into solution has occurred during purified recycled water recharge of shallow aquifers within Orange County, CA. Accordingly, we examine the geochemical processes controlling As desorption and mobilization from shallow, aerated sediments underlying MAR infiltration basins. Further, we conducted a series of batch and column experiments to evaluate recharge water chemistries that minimize the propensity of As desorption from the aquifer sediments. Within the shallow Orange County Groundwater Basin sediments, the divalent cations Ca(2+) and Mg(2+) are critical for limiting arsenic desorption; they promote As (as arsenate) adsorption to the phyllosilicate clay minerals of the aquifer. While native groundwater contains adequate concentrations of dissolved Ca(2+) and Mg(2+), these cations are not present at sufficient concentrations during recharge of highly purified recycled water. Subsequently, the absence of dissolved Ca(2+) and Mg(2+) displaces As from the sediments into solution. Increasing the dosages of common water treatment amendments including quicklime (Ca(OH)2) and dolomitic lime (CaO·MgO) provides recharge water with higher concentrations of Ca(2+) and Mg(2+) ions and subsequently decreases the release of As during infiltration.

Groundwater level responses to precipitation variability in Mediterranean insular aquifers

Science.gov (United States)

Lorenzo-Lacruz, Jorge; Garcia, Celso; Morán-Tejeda, Enrique

2017-09-01

Groundwater is one of the largest and most important sources of fresh water on many regions under Mediterranean climate conditions, which are exposed to large precipitation variability that includes frequent meteorological drought episodes, and present high evapotranspiration rates and water demand during the dry season. The dependence on groundwater increases in those areas with predominant permeable lithologies, contributing to aquifer recharge and the abundance of ephemeral streams. The increasing pressure of tourism on water resources in many Mediterranean coastal areas, and uncertainty related to future precipitation and water availability, make it urgent to understand the spatio-temporal response of groundwater bodies to precipitation variability, if sustainable use of the resource is to be achieved. We present an assessment of the response of aquifers to precipitation variability based on correlations between the Standardized Precipitation Index (SPI) at various time scales and the Standardized Groundwater Index (SGI) across a Mediterranean island. We detected three main responses of aquifers to accumulated precipitation anomalies: (i) at short time scales of the SPI (24 months). The differing responses were mainly explained by differences in lithology and the percentage of highly permeable rock strata in the aquifer recharge areas. We also identified differences in the months and seasons when aquifer storages are more dependent on precipitation; these were related to climate seasonality and the degree of aquifer exploitation or underground water extraction. The recharge of some aquifers, especially in mountainous areas, is related to precipitation variability within a limited spatial extent, whereas for aquifers located in the plains, precipitation variability influence much larger areas; the topography and geological structure of the island explain these differences. Results indicate large spatial variability in the response of aquifers to precipitation in

Toward an Economic Definition of Sustainable Yield for Coastal Aquifers

Science.gov (United States)

Jenson, J. W.; Habana, N. C.; Lander, M.

2016-12-01

The concept of aquifer sustainable yield has long been criticized, debated, and even disparaged among groundwater hydrologists, but policy-makers and professional water resource managers inevitably ask them for unequivocal answers to such questions as "What is the absolute maximum volume of water that could be sustainably withdrawn from this aquifer?" We submit that it is therefore incumbent upon hydrologists to develop and offer valid practical definitions of sustainable yield that can be usefully applied to given conditions and types of aquifers. In coastal aquifers, water quality—in terms of salinity—is affected by changes in the natural water budget and the volume rate of artificial extraction. In principle, one can identify a family of assay curves for a given aquifer, showing the specific relationships between the quantity and quality of the water extracted under given conditions of recharge. The concept of the assay curve, borrowed from the literature of natural-resource extraction economics, has to our knowledge not yet found its way into the literature of applied hydrology. The relationships between recharge, extraction, and water quality that define the assay curve can be determined empirically from sufficient observations of groundwater response to recharge and extraction and can be estimated from models that have been reliably history-matched ("calibrated") to such data. We thus propose a working definition of sustainable yield for coastal aquifers in terms of the capacity that ultimately could be achieved by an ideal production system, given what is known or can be assumed about the natural limiting conditions. Accordingly, we also offer an approach for defining an ideal production system for a given aquifer, and demonstrate how observational data and/or modeling results can be used to develop assay curves of quality vs. quantity extracted, which can serve as reliable predictive tools for engineers, managers, regulators, and policy

Hydraulic properties of the Midville Aquifer at the Savannah River Site, South Carolina

International Nuclear Information System (INIS)

Hodges, R.A.; Snipes, D.S.; Benson, S.M.; Daggett, J.S.; Temples, T.; Harrelson, L.

1994-01-01

Aquifer performance tests of the Midville Aquifer System were conducted at the Savannah River Site (SRS) in South Carolina. The stratigraphic section of interest consists of Late Cretaceous Coastal Plain sediments. Within the study area, the Midville Aquifer System is composed of sand aquifers separated by discontinuous clay lenses. The Midville is underlain by the Appleton Confining Unit which is separated from underlying Triassic sediments and Paleozoic crystallines by a regional unconformity. This unconformable surface has a dip of 10 m/km to the southeast. The Midville is overlain by the Allendale Confining Unit which separates the Midville from the Dublin Aquifer System. The tests were performed at B and P Areas within the SRS using production wells screened in the Midville Aquifer and monitor well clusters screened in the Midville, Dublin, and Gordon (Eocene) Aquifers. The B Area is located 13 km updip from P Area. The Midville is about 50 meters thick at B Area and 80 meters thick at P Area. The transmissivity of the Midville is 0.0095 m 2 /s at B Area and 0.017 m 2 /s at P Area. The storativity at both areas is about 10 -4 . Vertical leakance of the Midville is greater updip as the stratigraphic section thins. During the B Area test, pumping induced water level changes were detected in aquifers above the Midville. At P Area, no pumping induced water level changes were detected above the Midville Aquifer System

Aquifer thermal energy stores in Germany

International Nuclear Information System (INIS)

Kabus, F.; Seibt, P.; Poppei, J.

2000-01-01

This paper describes the state of essential demonstration projects of heat and cold storage in aquifers in Germany. Into the energy supply system of the buildings of the German Parliament in Berlin, there are integrated both a deep brine-bearing aquifer for the seasonal storage of waste heat from power and heat cogeneration and a shallow-freshwater bearing aquifer for cold storage. In Neubrandenburg, a geothermal heating plant which uses a 1.200 m deep aquifer is being retrofitted into an aquifer heat storage system which can be charged with the waste heat from a gas and steam cogeneration plant. The first centralised solar heating plant including an aquifer thermal energy store in Germany was constructed in Rostock. Solar collectors with a total area of 1000m 2 serve for the heating of a complex of buildings with 108 flats. A shallow freshwater-bearing aquifer is used for thermal energy storage. (Authors)

EPA Region 1 Sole Source Aquifers

Data.gov (United States)

U.S. Environmental Protection Agency — This coverage contains boundaries of EPA-approved sole source aquifers. Sole source aquifers are defined as an aquifer designated as the sole or principal source of...

Development and Modelling of a High-Resolution Aquifer Analog in the Guarani Aquifer (Brazil)

OpenAIRE

Höyng, Dominik

2014-01-01

A comprehensive and detailed knowledge about the spatial distribution of physical and chemical properties in heterogeneous porous aquifers plays a decisive role for a realistic representation of governing parameters in mathematical models. Models allow the simulation, prediction and reproduction of subsurface flow and transport characteristics. This work explains the identification, characterization and effects of small-scale aquifer heterogeneities in the Guarani Aquifer System (GAS) in S...

Hydrogeologic framework and salinity distribution of the Floridan aquifer system of Broward County, Florida

Science.gov (United States)

Reese, Ronald S.; Cunningham, Kevin J.

2014-01-01

Concerns about water-level decline and seawater intrusion in the surficial Biscayne aquifer, currently the principal source of water supply to Broward County, prompted a study to refine the hydrogeologic framework of the underlying Floridan aquifer system to evaluate its potential as an alternative source of supply. This report presents cross sections that illustrate the stratigraphy and hydrogeology in eastern Broward County; maps of the upper surfaces and thicknesses of several geologic formations or units within the Floridan aquifer system; and maps of two of the potentially productive water-bearing zones within the system, the Upper Floridan aquifer and the Avon Park permeable zone. An analysis of data on rock depositional textures, associated pore networks, and flow zones in the Floridan aquifer system shows that groundwater moves through the system in two ways. These data support a conceptual, dual-porosity model of the system wherein groundwater moves either as concentrated flow in discrete, thin bedding-plane vugs or zones of vuggy megaporosity, or as diffuse flow through rocks with primarily interparticle and moldic-particle porosity. Because considerable exchange of groundwater may occur between the zones of vuggy and matrix-dominated porosity, understanding the distribution of that porosity and flow zone types is important to evaluating the suitability of the several units within the Floridan aquifer system for managing the water through practices such as aquifer storage and recovery (ASR). The salinity of the water in the Floridan aquifer system is highest in the central part of the study area, and lower toward the north and south. Although salinity generally increases with depth, in the western part of the study area a zone of relatively high saline water is perched above water of lower salinity in the underlying Avon Park permeable zone. Overall, the areas of highest salinity in the aquifer system coincide with those with the lowest estimated

Groundwater vulnerability mapping in Guadalajara aquifers system (Western Mexico)

Science.gov (United States)

Rizo-Decelis, L. David; Marín, Ana I.; Andreo, Bartolomé

2016-04-01

Groundwater vulnerability mapping is a practical tool to implement strategies for land-use planning and sustainable socioeconomic development coherent with groundwater protection. The objective of vulnerability mapping is to identify the most vulnerable zones of catchment areas and to provide criteria for protecting the groundwater used for drinking water supply. The delineation of protection zones in fractured aquifers is a challenging task due to the heterogeneity and anisotropy of hydraulic conductivities, which makes difficult prediction of groundwater flow organization and flow velocities. Different methods of intrinsic groundwater vulnerability mapping were applied in the Atemajac-Toluquilla groundwater body, an aquifers system that covers around 1300 km2. The aquifer supplies the 30% of urban water resources of the metropolitan area of Guadalajara (Mexico), where over 4.6 million people reside. Study area is located in a complex neotectonic active volcanic region in the Santiago River Basin (Western Mexico), which influences the aquifer system underneath the city. Previous works have defined the flow dynamics and identified the origin of recharge. In addition, the mixture of fresh groundwater with hydrothermal and polluted waters have been estimated. Two main aquifers compose the multilayer system. The upper aquifer is unconfined and consists of sediments and pyroclastic materials. Recharge of this aquifer comes from rainwater and ascending vertical fluids from the lower aquifer. The lower aquifer consists of fractured basalts of Pliocene age. Formerly, the main water source has been the upper unit, which is a porous and unconsolidated unit, which acts as a semi-isotropic aquifer. Intense groundwater usage has resulted in lowering the water table in the upper aquifer. Therefore, the current groundwater extraction is carried out from the deeper aquifer and underlying bedrock units, where fracture flow predominates. Pollution indicators have been reported in

Water withdrawals and trends from the Floridan aquifer system in the southeastern United States, 1950-2000

Science.gov (United States)

Marella, Richard L.; Berndt, Marian P.

2005-01-01

The Floridan aquifer system in the southeastern United States is one of the most productive aquifers in the world (Miller, 1990). This aquifer system underlies an area of about 100,000 square miles in southern Alabama, eastern and southern Georgia, southeastern Mississippi, southern South Carolina, and all of Florida. The Floridan aquifer system is the primary source of water for nearly 10 million people and supports agriculture, industry, and tourism throughout most of the region. In most areas, water from this aquifer is potable and needs very little treatment before use. However, in southern Florida (south of Lake Okeechobee), northwestern Florida and southern Alabama and Mississippi (Pensacola and westward), and eastern South Carolina, water in the aquifer system generally is not potable. The purpose of this report is to: Provide a general description of the Floridan aquifer system; Discuss water withdrawals by category for 2000; Highlight trends in water withdrawals between 1950 and 2000; and Provide a brief summary on the effects that human impacts have on the Floridan aquifer system.

Investigating river–aquifer relations using water temperature in an anthropized environment (Motril-Salobreña aquifer)

DEFF Research Database (Denmark)

Duque, Carlos; Calvache, Marie; Engesgaard, Peter Knudegaard

2010-01-01

Heat was applied as a tracer for determining river–aquifer relations in the Motril-Salobreña aquifer (S Spain). The aquifer has typically been recharged by River Guadalfeo infiltration, nevertheless from 2005 a dam was constructed changing the traditional dynamic river flow and recharge events...

Review of Aquifer Storage and Recovery Performance in the Upper Floridan Aquifer in Southern Florida

Science.gov (United States)

Reese, Ronald S.

2006-01-01

Introduction: Interest and activity in aquifer storage and recovery (ASR) in southern Florida has increased greatly during the past 10 to 15 years. ASR wells have been drilled to the carbonate Floridan aquifer system at 30 sites in southern Florida, mostly by local municipalities or counties located in coastal areas. The primary storage zone at these sites is contained within the brackish to saline Upper Floridan aquifer of the Floridan aquifer system. The strategy for use of ASR in southern Florida is to store excess freshwater available during the wet season in an aquifer and recover it during the dry season when needed for supplemental water supply. Each ASR cycle is defined by three periods: recharge, storage, and recovery. This fact sheet summarizes some of the findings of a second phase retrospective assessment of existing ASR facilities and sites.

Geohydrologic units and water-level conditions in the Terrace alluvial aquifer and Paluxy Aquifer, May 1993 and February 1994, near Air Force Plant 4, Fort Worth area, Texas

Science.gov (United States)

Rivers, Glen A.; Baker, Ernest T.; Coplin, L.S.

1996-01-01

The terrace alluvial aquifer underlying Air Force Plant 4 and the adjacent Naval Air Station (formerly Carswell Air Force Base) in the Fort Worth area, Texas, is contaminated locally with organic and metal compounds. Residents south and west of Air Force Plant 4 and the Naval Air Station are concerned that contaminants might enter the underlying Paluxy aquifer, which provides water to the city of White Settlement, south of Air Force Plant 4, and to residents west of Air Force Plant 4. The U.S. Environmental Protection Agency has qualified Air Force Plant 4 for Superfund cleanup. The pertinent geologic units include -A~rom oldest to youngest the Glen Rose, Paluxy, and Walnut Formations, Goodland Limestone, and terrace alluvial deposits. Except for the Glen Rose Formation, all units crop out at or near Air Force Plant 4 and the Naval Air Station. The terrace alluvial deposits, which nearly everywhere form the land surface, range from 0 to about 60 feet thick. These deposits comprise a mostly unconsolidated mixture of gravel, sand, silt, and clay. Mudstone and sandstone of the Paluxy Formation crop out north, west, and southwest of Lake Worth and total between about 130 and about 175 feet thick. The terrace alluvial deposits and the Paluxy Formation comprise the terrace alluvial aquifer and the Paluxy aquifer, respectively. These aquifers are separated by the Goodland-Walnut confining unit, composed of the Goodland Limestone and (or) Walnut Formation. Below the Paluxy aquifer, the Glen Rose Formation forms the Glen Rose confining unit. Water-level measurements during May 1993 and February 1994 from wells in the terrace alluvial aquifer indicate that, regionally, ground water flows toward the east-southeast beneath Air Force Plant 4 and the Naval Air Station. Locally, water appears to flow outward from ground-water mounds maintained by the localized infiltration of precipitation and reportedly by leaking water pipes and sanitary and (or) storm sewer lines beneath the

Intrinsic bioremediation of petroleum hydrocarbons in a gas condensate-contaminated aquifer

International Nuclear Information System (INIS)

Gieg, L.M.; McInerney; Tanner, R.S.; Harris, S.H. Jr.; Sublette, K.L.; Suflita, J.M.; Kolhatkar, R.V.

1999-01-01

A study was designed to determine if the intrinsic bioremediation of gas condensate hydrocarbons represented an important fate process in a shallow aquifer underlying a natural gas production site. For over 4 yr, changes in the groundwater, sediment, and vadose zone chemistry in the contaminated portion of the aquifer were interpreted relative to a background zone. Changes included decreased dissolved oxygen and sulfate levels and increased alkalinity, Fe(II), and methane concentrations in the contaminated groundwater, suggesting that aerobic heterotrophic respiration depleted oxygen reserves leaving anaerobic conditions in the hydrocarbon-impacted subsurface. Dissolved hydrogen levels in the contaminated groundwater indicated that sulfate reduction and methanogenesis were predominant biological processes, corroborating the geochemical findings. Furthermore, 10--1000-fold higher numbers of sulfate reducers and methanogens were enumerated in the contaminated sediment relative to background. Putative metabolites were also detected in the contaminated groundwater, including methylbenzylsuccinic acid, a signature intermediate of anaerobic xylene decay. Laboratory incubations showed that benzene, toluene, ethylbenzene, and each of the xylene isomers were biodegraded under sulfate-reducing conditions as was toluene under methanogenic conditions. These results coupled with a decrease in hydrocarbon concentrations in contaminated sediment confirm that intrinsic bioremediation contributes to the attenuation of hydrocarbons in this aquifer

Geospatial compilation of historical water-level changes in the Chicot and Evangeline aquifers 1977-2013 and Jasper aquifer 2000-13, Gulf Coast aquifer system, Houston-Galveston region, Texas

Science.gov (United States)

Johnson, Michaela R.; Linard, Joshua I.

2014-01-01

The U.S. Geological Survey (USGS) in cooperation with the Harris-Galveston Subsidence District, City of Houston, Fort Bend Subsidence District, Lone Star Groundwater Conservation District, and Brazoria County Groundwater Conservation District has produced an annual series of reports that depict water-level changes in the Chicot, Evangeline, and Jasper aquifers of the Gulf Coast aquifer system in the Houston-Galveston region, Texas, from 1977 to 2013. Changes are determined from water-level measurements between December and March of each year from groundwater wells screened in one of the three aquifers. Existing published maps and unpublished geographic information system (GIS) datasets were compiled into a comprehensive geodatabase of all water-level-change maps produced as part of this multiagency effort. Annual water-level-change maps were georeferenced and digitized where existing GIS data were unavailable (1979–99). Existing GIS data available for 2000–13 were included in the geodatabase. The compilation contains 121 datasets showing water-level changes for each primary aquifer of the Gulf Coast aquifer system: 56 for the Chicot aquifer (1977; 1979–2013 and 1990; 1993–2013), 56 for the Evangeline aquifer (1977; 1979–2013 and 1990; 1993–2013), and 9 for the Jasper aquifer (2000; 2005–13).

Guarani aquifer

International Nuclear Information System (INIS)

2007-01-01

The environmental protection and sustain ability develop project of Guarani Aquifer System is a join work from Argentina, Brazil, Paraguay and Uruguay with a purpose to increase the knowledge resource and propose technical legal and organizational framework for sustainable management between countries.The Universities funds were created as regional universities support in promotion, training and academic research activities related to environmental al social aspects of the Guarani Aquifer System.The aim of the project is the management and protection of the underground waters resources taking advantage and assesment for nowadays and future generations

Fate of benzotriazole and 5-methylbenzotriazole in recycled water recharged into an anaerobic aquifer: column studies.

Science.gov (United States)

Alotaibi, M D; Patterson, B M; McKinley, A J; Reeder, A Y; Furness, A J; Donn, M J

2015-03-01

The fate of benzotriazole (BTri) and 5-methylbenzotriazole (5-MeBT) was investigated under anaerobic conditions at nano gram per litre concentrations in large-scale laboratory columns to mimic a managed aquifer recharge replenishment strategy in Western Australia. Investigations of BTri and 5-MeBT sorption behaviour demonstrated mobility of the compounds with retardation coefficients of 2.0 and 2.2, respectively. Degradation processes over a period of 220 days indicated first order biodegradation of the BTri and 5-MeBT under anaerobic aquifer conditions after a biological lag-time of approximately 30-60 days. Biodegradation half-lives of 29 ± 2 and 26 ± 1 days for BTri and 5-MeBT were respectively observed, with no threshold effect to biodegradation observed at the 200 ng L(-1). The detection of degradation products provided further evidence of BTri and 5-MeBT biodegradation. These results suggested that if BTri and 5-MeBT were present in recycled water recharged to the Leederville aquifer, biodegradation during aquifer passage is likely given sufficient aquifer residence times or travel distances between recycled water injection and groundwater extraction. Crown Copyright © 2014. Published by Elsevier Ltd. All rights reserved.

Recovery of energetically overexploited urban aquifers using surface water

Science.gov (United States)

García-Gil, Alejandro; Vázquez-Suñé, Enric; Sánchez-Navarro, José Ángel; Mateo Lázaro, Jesús

2015-12-01

Shallow aquifers have an important role in reducing greenhouse gases through helping manage the temperature of urban environments. Nevertheless, the uncontrolled rapid use of shallow groundwater resources to heat or cool urban environments can cause thermal pollution that will limit the long term sustainability of the resource. Therefore, there is a need for appropriate mitigation/remediation strategies capable of recovering energetically overexploited aquifers. In this work, a novel remediation strategy based on surface water recharge into aquifers is presented. To evaluate the capabilities of such measures for effective remediation, this strategy is optimized for a management problem raised in the overheated "Urban Alluvial Aquifer of Zaragoza" (Spain). The application of a transient groundwater flow and heat transport model under 512 different mitigation scenarios has enabled to quantify and discuss the magnitude of the remediation effect as a respond to injection rates of surface water, seasonal schedule of the injection and location of injection. The quantification of the relationship between these variables together with the evaluation of the amount of surface water injected per year in each scenario proposed have provided a better understanding of the system processes and an optimal management alternative. This work also makes awareness of the magnitude of the remediation procedure which is in an order of magnitude of tenths of years.

Contribution to the hydrogeological, geochemical and isotopic study of Ain El Beidha and Merguellil (Kairouan plain) aquifers: Implication for the dam-aquifer relationship

International Nuclear Information System (INIS)

Ben Ammar, Safouan

2007-01-01

In the semiarid central part of Tunisia the water resources are becoming increasingly rare because of the scarcity and irregularity of the precipitation and a steadily growing need for fresh water. This study addresses the use of geochemical and isotopic data to analyze the relationship between the El Haouareb dam and the Ain El Beidha and the Kairouan alluvial plain aquifers systems for durable groundwater management. In the Ain El Beidha basin the hydrogeological and geochemical investigations showed that: - The general direction of the groundwater flow is mainly from the SW to the NE, i.e. towards the hydraulic sill of El Haouareb which allows the connection between the Ain El Beidha basin and the Kairouan plain, - The salinity distribution displays a zonation in apparent relationship with the lithological variation of the aquifer formation, - Mineral exchange between groundwater and the aquifer matrix is the dominant process in determining groundwater salinity. The isotopic data confirm the flow directions of groundwater and shows that the recharge of Ain El Beidha aquifers takes place from the floods of the Khechem and Ben Zitoun wadies and also by preferential infiltration of runoff at the front of hill slopes area. Close to preferential recharge areas, groundwater 3H contents reflect a recent input of surface water, whereas the radiocarbon data indicate a longer residence time downstream. The isotopic characteristics of Ain El Beidha groundwater (small space and temporal changes) authorize the use of averaged values for the dam-aquifer water exchange. Under natural conditions, groundwater recharge of the alluvial aquifer of Kairouan plain occurs by infiltration of the Merguellil floods and from the Ain el Beidha groundwater flow close the karstic hydraulic sills. Since the construction of the El Haouareb dam, these natural mechanisms have been strongly modified: the dam waters infiltrate into the karst, mix with the Ain el Beidha groundwater, and feed the

Development of A Mississippi River Alluvial Aquifer Groundwater Model

Science.gov (United States)

Karakullukcu, R. E.; Tsai, F. T. C.; Bhatta, D.; Paudel, K.; Kao, S. C.

2017-12-01

The Mississippi River Alluvial Aquifer (MRAA) underlies the Mississippi River Valley of the northeastern Louisiana, extending from the north border of Louisiana and Arkansas to south central of Louisiana. The MRAA has direct contact with the Mississippi River. However, the interaction between the Mississippi River and the alluvial aquifer is largely unknown. The MRAA is the second most used groundwater source in Louisiana's aquifers with about 390 million gallons per day, which is about 25% of all groundwater withdrawals in Louisiana. MRAA is the major water source to agriculture in the northeastern Louisiana. The groundwater withdrawals from the MRAA increases annually for irrigation. High groundwater pumping has caused significant groundwater level decline and elevated salinity in the aquifer. Therefore, dealing with agricultural irrigation is the primary purpose for managing the MRAA. The main objective of this study is to develop a groundwater model as a tool for the MRAA groundwater management. To do so, a hydrostratigraphy model of the MRAA was constructed by using nearly 8,000 drillers' logs and electric logs collected from Louisiana Department of Natural Resources. The hydrostratigraphy model clearly shows that the Mississippi River cuts into the alluvial aquifer. A grid generation technique was developed to convert the hydrostratigraphy model into a MODFLOW model with 12 layers. A GIS-based method was used to estimate groundwater withdrawals for irrigation wells based on the crop location and acreage from the USDACropScape - Cropland Data Layer. Results from the Variable Infiltration Capacity (VIC) model were used to determine potential recharge. NHDPlusV2 data was used to determine water level for major streams for the MODFLOW River Package. The groundwater model was calibrated using groundwater data between 2004 and 2015 to estimate aquifer hydraulic conductivity, specific yield, specific storage, river conductance, and surficial recharge.

Impact of lateral flow on the transition from connected to disconnected stream-aquifer systems

Science.gov (United States)

Xian, Yang; Jin, Menggui; Liu, Yanfeng; Si, Aonan

2017-05-01

Understanding the mechanisms by which stream water infiltrates through streambeds to recharge groundwater systems is essential to sustainable management of scarce water resources in arid and semi-arid areas. An inverted water table (IWT) can develop under a stream in response to the desaturation between the stream and underlying aquifer as the system changes from a connected to disconnected status. However, previous studies have suggested that the IWT can only occur at the bottom of a low permeability streambed in which only the vertical flow between the stream and groundwater during disconnection was assumed. In the present study, numerical simulations revealed that the lateral flow induced by capillarity or heterogeneity also plays an essential role on interactions between streams and aquifers. Three pathways were identified for the transition from connection to disconnection in homogenous systems; notably, the lowest point of an IWT can develop not only at the bottom of the streambed but also within the streambed or the aquifer in response to the initial desaturation at, above, or below the interface between the streambed and aquifer (IBSA), respectively. A sensitivity analysis indicated that in wide streams, the lowest point of an IWT only occurs at the bottom of the streambed; however, for a stream half width of 1 m above a 6 m thick sandy loam streambed, the lowest point occurs in the streambed as stream depth is less than 0.5 m. This critical stream depth increases with streambed thickness and decreases with stream width. Thus, in narrow streams the lowest point can also develop in a thick streambed under a shallow stream. In narrow streams, the lowest point also forms in the aquifer if the ratio of the hydraulic conductivity of the streambed to that of the aquifer is greater than the ratio of the streambed thickness to the sum of the stream depth and the streambed thickness; correspondingly, the streambed is thin but relatively permeable and the stream is

Effect of climate change on sea water intrusion in coastal aquifers

Science.gov (United States)

Sherif, Mohsen M.; Singh, Vijay P.

1999-06-01

There is increasing debate these days on climate change and its possible consequences. Much of this debate has focused in the context of surface water systems. In many arid areas of the world, rainfall is scarce and so is surface runoff. These areas rely heavily on groundwater. The consequences of climate change on groundwater are long term and can be far reaching. One of the more apparent consequences is the increased migration of salt water inland in coastal aquifers. Using two coastal aquifers, one in Egypt and the other in India, this study investigates the effect of likely climate change on sea water intrusion. Three realistic scenarios mimicking climate change are considered. Under these scenarios, the Nile Delta aquifer is found to be more vulnerable to climate change and sea level rise.

New methodology for aquifer influx status classification for single wells in a gas reservoir with aquifer support

Directory of Open Access Journals (Sweden)

Yong Li

2016-10-01

Full Text Available For gas reservoirs with strong bottom or edge aquifer support, the most important thing is avoiding aquifer breakthrough in a gas well. Water production in gas wells does not only result in processing problems in surface facilities, but it also explicitly reduces well productivity and reservoir recovery. There are a lot of studies on the prediction of water breakthrough time, but they are not completely practicable due to reservoir heterogeneity. This paper provides a new method together with three diagnostic curves to identify aquifer influx status for single gas wells; the aforementioned curves are based on well production and pressure data. The whole production period of a gas well can be classified into three periods based on the diagnostic curves: no aquifer influx period, early aquifer influx period, and middle-late aquifer influx period. This new method has been used for actual gas well analysis to accurately identify gas well aquifer influx status and the water breakthrough sequence of all wells in the same gas field. Additionally, the evaluation results are significantly beneficial for well production rate optimization and development of an effective gas field.

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

Increasing freshwater recovery upon aquifer storage : A field and modelling study of dedicated aquifer storage and recovery configurations in brackish-saline aquifers

NARCIS (Netherlands)

Zuurbier, Koen

2016-01-01

The subsurface may provide opportunities for robust, effective, sustainable, and cost-efficient freshwater management solutions. For instance, via aquifer storage and recovery (ASR; Pyne, 2005): “the storage of water in a suitable aquifer through a well during times when water is available, and the

Groundwater Quality and Quantity in a Coastal Aquifer Under High Human Pressure: Understand the Aquifer Functioning and the Social Perception of Water Use for a Better Water Management. Example of Recife (PE, Brazil)

Science.gov (United States)

Petelet-Giraud, E.; Cary, L.; Bertrand, G.; Alves, L. M.; Cary, P.; Giglio-Jacquemot, A.; Aquilina, L.; Hirata, R.; Montenegro, S.; Aurouet, A.; Franzen, M.; Chatton, E.

2015-12-01

The Recife Metropolitan Region is a typical "hot spot" illustrating the problems of southern countries on water issues inducing high pressures on water resources both on quantity and quality in the context of global social and environmental changes. This study is based on an interdisciplinary approach, coupling "hard" geosciences together with "soft" social sciences with the aim to study the human impact on coastal aquifers in a context of overexploitation to improve the existing water management tools. By revisiting the geological and hydrogeological conceptual models, field campaigns of groundwater and surface water sampling and analysis, and of interviews of different actors on the theme of water supply and management in Recife Metropolitan Region, the main results can be summarized as follows: (1) The recharge of the deep strategic confined aquifers is very limited resulting in water level decrease (up to -90m in 25y) due to overexploitation. (2) Groundwater residence time in these deep aquifers is over 10,000 years. (3) The natural upward flux of these confined aquifers is observed inland, but is reversed in the heavily populated areas along the coast leading to mixing with modern groundwater coming from the shallow aquifers. (4) Groundwater salinization is inherited from the Pleistocene marine transgression, only partly diluted by the recharge through the mangroves during the subsequent regression phase. Today, leakage from surficial aquifers induces local salinization. (5) Local climatic scenarios predict a reduction of rainfall volume of 20% together with an increase of sea level (18-59cm by 2100). (5) The Public authorities tend to deny the difficulties that people, especially those in precarious situation, are confronted with regarding water, especially in times of drought. The COQUEIRAL research project is financially supported by ANR (ANR-11-CEPL-012); FACEPE (APQ-0077-3.07/11); FAPESP (2011/50553-0

Three-dimensional geologic model of the Arbuckle-Simpson aquifer, south-central Oklahoma

Science.gov (United States)

Faith, Jason R.; Blome, Charles D.; Pantea, Michael P.; Puckette, James O.; Halihan, Todd; Osborn, Noel; Christenson, Scott; Pack, Skip

2010-01-01

The Arbuckle-Simpson aquifer of south-central Oklahoma encompasses more than 850 square kilometers and is the principal water resource for south-central Oklahoma. Rock units comprising the aquifer are characterized by limestone, dolomite, and sandstones assigned to two lower Paleozoic units: the Arbuckle and Simpson Groups. Also considered to be part of the aquifer is the underlying Cambrian-age Timbered Hills Group that contains limestone and sandstone. The highly faulted and fractured nature of the Arbuckle-Simpson units and the variable thickness (600 to 2,750 meters) increases the complexity in determining the subsurface geologic framework of this aquifer. A three-dimensional EarthVision (Trademark) geologic framework model was constructed to quantify the geometric relationships of the rock units of the Arbuckle-Simpson aquifer in the Hunton anticline area. This 3-D EarthVision (Trademark) geologic framework model incorporates 54 faults and four modeled units: basement, Arbuckle-Timbered Hills Group, Simpson Group, and post-Simpson. Primary data used to define the model's 54 faults and four modeled surfaces were obtained from geophysical logs, cores, and cuttings from 126 water and petroleum wells. The 3-D framework model both depicts the volumetric extent of the aquifer and provides the stratigraphic layer thickness and elevation data used to construct a MODFLOW version 2000 regional groundwater-flow model.

Potentiometric surfaces of the intermediate aquifer system, west-central Florida, May, 1993

Science.gov (United States)

Mularoni, R.A.

1994-01-01

The intermediate aquifer system underlies a 5000-sq-mi area including De Soto, Sarasota, Hardee, Manatee, and parts of Charlotte, Hillsborough, Highlands, and Polk Counties, Florida. It is overlain by the surf@cial aquifer system and underlain by the Floridan aquifer system. The potentiometric surface of the intermediate aquifer system was mapped by determining the altitude of water levels in a network of wells and represented on a map by contours that connect points of equal altitude. This map represents water-level conditions near the end of the spring dry season when ground- water withdrawals for agricultural use were high. The cumulative rainfall for the study area was 4.84 inches above normal for the period from June 1992 to May 1993. Hydrographs for selected wells indicated that the annual and seasonal fluctuations of the water levels were generally large (greater than 15 feet) in the central interior region where water demand for irrigation is high during the fall and spring. Seasonal fluctuations were smaller in the northern recharge area where water use is predominantly for public supply. Water levels measured in May 1993 for the composite intermediate aquifer potentiometric surface were lower than those measured in May or September 1992. A cone of depression exists in the potentiometric surface for the composite aquifer system at Warm Mineral Springs, which is a natural discharge point from this system.

Aquifers

Data.gov (United States)

Earth Data Analysis Center, University of New Mexico — This map layer contains the shallowest principal aquifers of the conterminous United States, Hawaii, Puerto Rico, and the U.S. Virgin Islands, portrayed as polygons....

Subsurface imaging reveals a confined aquifer beneath an ice-sealed Antarctic lake

DEFF Research Database (Denmark)

Dugan, H. A.; Doran, P. T.; Tulaczyk, S.

2015-01-01

Liquid water oases are rare under extreme cold desert conditions found in the Antarctic McMurdo Dry Valleys. Here we report geophysical results that indicate that Lake Vida, one of the largest lakes in the region, is nearly frozen and underlain by widespread cryoconcentrated brine. A ground...... this zone to be a confined aquifer situated in sediments with a porosity of 23-42%. Discovery of this aquifer suggests that subsurface liquid water may be more pervasive in regions of continuous permafrost than previously thought and may represent an extensive habitat for microbial populations. Key Points...... Geophysical survey finds low resistivities beneath a lake in Antarctic Dry Valleys Liquid brine abundant beneath Antarctic lake Aquifer provides microbial refugium in cold desert environment...

Variations of uranium concentrations in a multi-aquifer system under the impact of surface water-groundwater interaction

Science.gov (United States)

Wu, Ya; Li, Junxia; Wang, Yanxin; Xie, Xianjun

2018-04-01

Understanding uranium (U) mobility is vital to minimizing its concentrations in potential drinking water sources. In this study, we report spatial-seasonal variations in U speciation and concentrations in a multi-aquifer system under the impact of Sanggan River in Datong basin, northern China. Hydrochemical and H, O, Sr isotopic data, thermodynamic calculations, and geochemical modeling are used to investigate the mechanisms of surface water-groundwater mixing-induced mobilization and natural attenuation of U. In the study site, groundwater U concentrations are up to 30.2 μg/L, and exhibit strong spatial-seasonal variations that are related to pH and Eh values, as well as dissolved Ca2+, HCO3-, and Fe(III) concentrations. For the alkaline aquifers of this site (pH 7.02-8.44), U mobilization is due to the formation and desorption of Ca2UO2(CO3)30 and CaUO2(CO3)32- caused by groundwater Ca2+ elevation via mineral weathering and Na-Ca exchange, incorporated U(VI) release from calcite, and U(IV) oxidation by Fe(OH)3. U immobilization is linked to the adsorption of CaUO2(CO3)32- and UO2(CO3)34- shifted from Ca2UO2(CO3)30 because of HCO3- elevation and Ca2+ depletion, U(VI) co-precipitation with calcite, and U(VI) reduction by adsorbed Fe2+ and FeS. Those results are of great significance for the groundwater resource management of this and similar other surface water-groundwater interaction zones.

Cenomanian-Turonian aquifer of central Israel, its development and possible use as a storage reservoir

Science.gov (United States)

Schneider, Robert

1964-01-01

The Cenomanian-Turonian formations constitute a highly permeable dolomite and limestone aquifer in central Israel. The aquifer is on the west limb of an anticlinorium that trends north-northeast. In places it may be as much as 800 meters thick, but in the report area, largely the foothills of the Judean-Ephraim Mountains where the water development is most intensive, its thickness is generally considerably less. In some places the aquifer occurs at or near the land surface, or it is covered by sandy and gravelly coastal-plain deposits. However, in a large part of the area, it is overlain by as much as 400 meters of relatively impermeable strata, and it is probably underlain by less permeable Lower Cretaceous strata. In general the aquifer water is under artesian pressure. The porosity of the aquifer is characterized mainly by solution channels and cavities produced by jointing and faulting. In addition to the generally high permeability of the aquifer, some regions, which probably coincide with ancient drainage patterns and (or) fault zones, have exceptionally high permeabilities. The source of most of the water in the aquifer is believed to be rain that falls on the foothills area. The westward movement of ground water from the mountainous outcrop areas appears to be impeded by a zone of low permeability which is related to structural and stratigraphic conditions along the western side of the mountains. Gradients of the piezometric surface are small, and the net direction of water movement is westward and northwestward under natural conditions. Locally, however, the flow pattern may be in other directions owing to spatial variations in permeability in the aquifer, the location of natural discharge outlets, and the relation of the aquifer to adjacent geologic formations. There probably is also a large vertical component of flow. Pumping has modified the flow pattern by producing several irregularly shaped shallow depressions in the piezometric surface although, to

Drought risk and climate change impacts on Querença-Silves aquifer and Odelouca watershed (Algarve)

OpenAIRE

Novo, M. E.; Oliveira, L. G. S.

2014-01-01

The evolution aquifer recharge and runoff in Querença-Silves aquifer and Odelouca watershed under three emissions scenarios (IS92a, SRES A2 e SRES B2), for year 2100, was calculated using BALSEQ daily water balance and a methodology developed by Oliveira et al. (2012) to generate the hydrological data required by this model. The results hint at a future drier climate regimes, with significant runoff reductions of 11 to 12% in Odelouca watershed and Querença-Silves aquifer while...

Geospatial compilation of historical water-level altitudes in the Chicot and Evangeline aquifers 1977-2013 and Jasper aquifer 2000-13 in the Gulf Coast aquifer system, Houston-Galveston Region, Texas

Science.gov (United States)

Johnson, Michaela R.; Ellis, Robert H.H.

2013-01-01

The U.S. Geological Survey (USGS) in cooperation with the Harris-Galveston Subsidence District, City of Houston, Fort Bend Subsidence District, Lone Star Groundwater Conservation District, and Brazoria County Groundwater Conservation District has produced a series of annual reports depicting groundwater-level altitudes in the Chicot, Evangeline, and Jasper aquifers of the Gulf Coast aquifer system in the Houston-Galveston region, Texas. To produce these annual reports, contours of equal water-level altitudes are created from water levels measured between December and March of each year from groundwater wells screened completely within one of these three aquifers. Information obtained from maps published in the annual series of USGS reports and geospatial datasets of water-level altitude contours used to create the annual series of USGS reports were compiled into a comprehensive geodatabase. The geospatial compilation contains 88 datasets from previously published contour maps showing water-level altitudes for each primary aquifer of the Gulf Coast aquifer system, 37 for the Chicot (1977–2013), 37 for the Evangeline aquifer (1977–2013), and 14 for the Jasper aquifer (2000–13).

Volcanic aquifers of Hawai‘i—Hydrogeology, water budgets, and conceptual models

Science.gov (United States)

Izuka, Scot K.; Engott, John A.; Rotzoll, Kolja; Bassiouni, Maoya; Johnson, Adam G.; Miller, Lisa D.; Mair, Alan

2016-06-13

Hawai‘i’s aquifers have limited capacity to store fresh groundwater because each island is small and surrounded by saltwater. Saltwater also underlies much of the fresh groundwater. Fresh groundwater resources are, therefore, particularly vulnerable to human activity, short-term climate cycles, and long-term climate change. Availability of fresh groundwater for human use is constrained by the degree to which the impacts of withdrawal—such as lowering of the water table, saltwater intrusion, and reduction in the natural discharge to springs, streams, wetlands, and submarine seeps—are deemed acceptable. This report describes the hydrogeologic framework, groundwater budgets (inflows and outflows), conceptual models of groundwater occurrence and movement, and the factors limiting groundwater availability for the largest and most populated of the Hawaiian Islands—Kaua‘i, O‘ahu, Maui, and Hawai‘i Island.The bulk of each of Hawai‘i’s islands is built of many thin lava flows erupted from shield volcanoes; the great piles of lava flows form highly permeable aquifers. In some areas, low-permeability dikes cutting across the lava flows, or low-permeability ash and soil horizons interlayered with the lava flows, can substantially alter groundwater flow. On some islands, sedimentary rocks form thick semiconfining coastal-plain deposits, locally known as caprock, that impede natural groundwater discharge to the ocean. In some regions, thick lava flows that ponded in preexisting depressions form aquifers that are much less permeable than aquifers formed by thin lava flows.Fresh groundwater inflow to Hawai‘i’s aquifers comes from recharge. For predevelopment conditions (1870), estimates of groundwater recharge from this study are 871, 675, 1,279, and 5,291 million gallons per day (Mgal/d) for Kaua‘i, O‘ahu, Maui, and Hawai‘i Island, respectively. Estimates of recharge for recent conditions (2010 land cover and 1978–2007 rainfall for Kaua‘i, O�

Modeling of drainage and hay production over the Crau aquifer for analyzing the impact of global change on aquifer recharge

Science.gov (United States)

Olioso, Albert; Lecerf, Rémi; Baillieux, Antoine; Chanzy, André; Ruget, Françoise; Banton, Olivier; Lecharpentier, Patrice; Alkassem Alosman, Mohamed; Ruy, Stéphane; Gallego Elvira, Belen

2013-04-01

The recharge of the aquifer in the Crau plain (550 km2, Southern Rhone Valley, France) depends on the irrigation of 15000 ha of meadow using water withdrawn from the River Durance through a dense network of channels. Traditional irrigation practice, since the XVIth century, has consisted in flooding the grassland fields with a large amount of water, the excess being infiltrated toward the water table. Today, the Crau aquifer holds the main resource in water in the area (300 000 inhabitants) but changes in the agricultural practices and progressive replacement of the irrigated meadows by urbanized area threaten the sustainability of groundwater. The distributed modeling of irrigated meadows together with the modeling of groundwater has been undertaken for quantifying the contribution of the irrigation to the recharge of the aquifer and to investigate possible evolution of hay production, water drainage, evapotranspiration and water table under scenarios of climate and land-use changes. The model combines a crop model (STICS) that simulates hay production, evapotranspiration and water drainage, a multisimulation tool (MultiSimLib) that allows to run STICS over each agricultural field in the aquifer perimeter, a groundwater model MODFLOW to simulate the water table from recharge data (simulated drainage). Specific models were developed for simulating the spatial distribution of climate, including scenario of changes for the 2025 - 2035 time period, soil properties (influenced by irrigation), and agricultural practices (calendar and amount), in particular irrigation and hay cutting. This step was crucial for correctly simulating hay production level and amount of water used for irrigation. Model results were evaluated thanks to plot experiments and information from farmers (biomass production, downward water flow, quantity of irrigated water, cutting calendar...), a network of piezometers and remote sensing maps of evapotranspiration. Main results included: - the

Sorption of benzothiazoles onto sandy aquifer material under equilibrium and nonequlibrium conditions

Directory of Open Access Journals (Sweden)

Kragulj Marijana M.

2014-01-01

Full Text Available In this study, the sorption behaviour of 1,3-benzothiazole (BT and 2-(methylthiobenzothiazole (MTBT was investigated on Danube geosorbent under equilibrium and nonequilibrium conditions. All sorption isotherms fitted well with the Freundlich model (R2=0.932-0.993. The results showed that organic matter of the Danube geosorbent has a higher sorption affinity for the more hydrophobic MTBT compared to BT. However, sorption-desorption experiments showed that MTBT was more easily desorbed than BT molecules, which indicates the importance of absorption relative to adsorption in the overall sorption mechanism of MTBT. In general, molecules of BT and MTBT were more easily desorbed in the lower concentration range, which resulted in an increase in the hysteresis indices with increasing concentrations. Column experiments revealed that retention of the investigated compounds on the aquifer material followed the compound’s hydrophobicity. BT showed a lower retention, in accordance with its lower sorption affinity obtained in the static experiments, while MTBT showed a greater sorption affinity, and thus had a longer retention time on the column. Thus during transport BT represent greater risk for groundwaters than MTBT. These results have increased our understanding of benzothiazoles sorption and desorption process which represent one of the most important factors which influence the behaviour of organic compounds in the environment.

Can Remote Sensing Detect Aquifer Characteristics?: A Case Study in the Guarani Aquifer System

Science.gov (United States)

Richey, A. S.; Thomas, B.; Famiglietti, J. S.

2013-12-01

Global water supply resiliency depends on groundwater, especially regions threatened by population growth and climate change. Aquifer characteristics, even as basic as confined versus unconfined, are necessary to prescribe regulations to sustainably manage groundwater supplies. A significant barrier to sustainable groundwater management exists in the difficulties associated with mapping groundwater resources and characteristics at a large spatial scale. This study addresses this challenge by investigating if remote sensing, including with NASA's Gravity Recovery and Climate Experiment (GRACE), can detect and quantify key aquifer parameters and characteristics. We explore this through a case study in the Guarani Aquifer System (GAS) of South America, validating our remote sensing-based findings against the best available regional estimates. The use of remote sensing to advance the understanding of large aquifers is beneficial to sustainable groundwater management, especially in a trans-boundary system, where consistent information exchange can occur within hydrologic boundaries instead of political boundaries.

Geologic history and hydrogeologic setting of the Edwards-Trinity aquifer system, west-central Texas

Science.gov (United States)

Barker, R.A.; Bush, P.W.; Baker, E.T.

1994-01-01

The Edwards-Trinity aquifer system underlies about 42,000 square miles of west-central Texas. Nearly flat-lying, mostly Comanche (Lower Cretaceous) strata of the aquifer system thin northwestward atop massive pre-Cretaceous rocks that are comparatively impermeable and structurally complex. From predominately terrigenous clastic sediments in the east and fluvialdeltaic (terrestrial) deposits in the west, the rocks of early Trinitian age grade upward into supratidal evaporitic and dolomitic strata, intertidal limestone and dolostone, and shallow-marine, openshelf, and reefal strata of late Trinitian, Fredericksburgian, and Washitan age. A thick, downfaulted remnant of mostly open-marine strata of Eaglefordian through Navarroan age composes a small, southeastern part of the aquifer system.

Estimating Aquifer Properties Using Sinusoidal Pumping Tests

Science.gov (United States)

Rasmussen, T. C.; Haborak, K. G.; Young, M. H.

2001-12-01

We develop the theoretical and applied framework for using sinusoidal pumping tests to estimate aquifer properties for confined, leaky, and partially penetrating conditions. The framework 1) derives analytical solutions for three boundary conditions suitable for many practical applications, 2) validates the analytical solutions against a finite element model, 3) establishes a protocol for conducting sinusoidal pumping tests, and 4) estimates aquifer hydraulic parameters based on the analytical solutions. The analytical solutions to sinusoidal stimuli in radial coordinates are derived for boundary value problems that are analogous to the Theis (1935) confined aquifer solution, the Hantush and Jacob (1955) leaky aquifer solution, and the Hantush (1964) partially penetrated confined aquifer solution. The analytical solutions compare favorably to a finite-element solution of a simulated flow domain, except in the region immediately adjacent to the pumping well where the implicit assumption of zero borehole radius is violated. The procedure is demonstrated in one unconfined and two confined aquifer units near the General Separations Area at the Savannah River Site, a federal nuclear facility located in South Carolina. Aquifer hydraulic parameters estimated using this framework provide independent confirmation of parameters obtained from conventional aquifer tests. The sinusoidal approach also resulted in the elimination of investigation-derived wastes.

Hydrogeological and quantitative groundwater assessment of the Basaltic Aquifer, Northern Harrat Rahat, Saudi Arabia

International Nuclear Information System (INIS)

Al-Shaibani, A.; Abokhodair, Abdulwahab A.; Lloyd, J.W.; Al-Ahmari, A.

2007-01-01

The Northern Harrat Rahat consists of 300m basalt lavas covering some 2000 km2 to the south-east of Al-Madinah in western Saudi Arabia. Like many basalt sequences, the Rahat basalts form an important aquifer and groundwater resource. The aquifer has a saturated thickness of up to 60m and made up of the weathered upper part of underlying basement, pre-basalt sands and gravels and the fractured basalts. Since 1992, groundwater has been abstracted from the aquifer as part of the Al-Madinah water supply. To assess the potential of the aquifer an assessment has been made based on pumping tests of 70 wells. The hydraulic parameters have been shown to be highly variable typical of the fractured domain. The aquifer contains good-quality water in storage, but receives limited recharge. Groundwater temperature anomalies indicate remnant volcanic activity locally. A numerical groundwater model has been constructed, which has been calibrated using limited groundwater head measurements, but with good abstraction records. Prediction of groundwater heads and the examination of several abstraction scenarios indicate that the aquifer can continue to support part of the Al-Madinah demand for the next several years, if certain well distributions are adopted. The predictions also show that the aquifer can only support the total demand of the city for a few days as a contingency resource. (author)

Water-quality characteristics of quaternary unconsolidated-deposit aquifers and lower tertiary aquifers of the Bighorn Basin, Wyoming and Montana, 1999-2001

Science.gov (United States)

Bartos, Timothy T.; Eddy-Miller, Cheryl A.; Norris, Jody R.; Gamper, Merry E.; Hallberg, Laura L.

2004-01-01

As part of the Yellowstone River Basin National Water Quality Assessment study, ground-water samples were collected from Quaternary unconsolidated-deposit and lower Tertiary aquifers in the Bighorn Basin of Wyoming and Montana from 1999 to 2001. Samples from 54 wells were analyzed for physical characteristics, major ions, trace elements, nutrients, dissolved organic carbon, radionuclides, pesticide compounds, and volatile organic compounds (VOCs) to evaluate current water-quality conditions in both aquifers. Water-quality samples indicated that waters generally were suitable for most uses, and that natural conditions, rather than the effects of human activities, were more likely to limit uses of the waters. Waters in both types of aquifers generally were highly mineralized, and total dissolved-solids concentrations frequently exceeded the U.S. Environmental Protection Agency (USEPA) Secondary Maximum Contaminant Level (SMCL) of 500 milligrams per liter (mg/L). Because of generally high mineralization, waters from nearly one-half of the samples from Quaternary aquifers and more than one-half of the samples from lower Tertiary aquifers were not classified as fresh (dissolved-solids concentration were not less than 1,000 mg/L). The anions sulfate, fluoride, and chloride were measured in some ground-water samples at concentrations greater than SMCLs. Most waters from the Quaternary aquifers were classified as very hard (hardness greater than 180 mg/L), but hardness varied much more in waters from the lower Tertiary aquifers and ranged from soft (less than 60 mg/L) to very hard (greater than 180 mg/L). Major-ion chemistry varied with dissolved-solids concentrations. In both types of aquifers, the predominant anion changes from bicarbonate to sulfate with increasing dissolved-solids concentrations. Samples from Quaternary aquifers with fresh waters generally were calcium-bicarbonate, calcium-sodium-bicarbonate, and calcium-sodium-sulfate-bicarbonate type waters, whereas

Effects of Barometric Fluctuations on Well Water-Level Measurements and Aquifer Test Data

Energy Technology Data Exchange (ETDEWEB)

FA Spane, Jr.

1999-12-16

The Pacific Northwest National Laboratory, as part of the Hanford Groundwater Monitoring Project, examines the potential for offsite migration of contamination within underlying aquifer systems. Well water-level elevation measurements from selected wells within these aquifer systems commonly form the basis for delineating groundwater-flow patterns (i.e., flow direction and hydraulic gradient). In addition, the analysis of water-level responses obtained in wells during hydrologic tests provides estimates of hydraulic properties that are important for evaluating groundwater-flow velocity and transport characteristics. Barometric pressure fluctuations, however, can have a discernible impact on well water-level measurements. These barometric effects may lead to erroneous indications of hydraulic head within the aquifer. Total hydraulic head (i.e., sum of the water-table elevation and the atmospheric pressure at the water-table surface) within the aquifer, not well water-level elevation, is the hydrologic parameter for determining groundwater-flow direction and hydraulic gradient conditions. Temporal variations in barometric pressure may also adversely affect well water-level responses obtained during hydrologic tests. If significant, adjustments or removal of these barometric effects from the test-response record may be required for quantitative hydraulic property determination. This report examines the effects of barometric fluctuations on well water-level measurements and evaluates adjustment and removal methods for determining areal aquifer head conditions and aquifer test analysis. Two examples of Hanford Site unconfined aquifer tests are examined that demonstrate barometric response analysis and illustrate the predictive/removal capabilities of various methods for well water-level and aquifer total head values. Good predictive/removal characteristics were demonstrated with best corrective results provided by multiple-regression deconvolution methods.

WTAQ - A computer program for aquifer-test analysis of confined and unconfined aquifers

Science.gov (United States)

Barlow, P.M.; Moench, A.F.

2004-01-01

Computer program WTAQ was developed to implement a Laplace-transform analytical solution for axial-symmetric flow to a partially penetrating, finite-diameter well in a homogeneous and anisotropic unconfined (water-table) aquifer. The solution accounts for wellbore storage and skin effects at the pumped well, delayed response at an observation well, and delayed or instantaneous drainage from the unsaturated zone. For the particular case of zero drainage from the unsaturated zone, the solution simplifies to that of axial-symmetric flow in a confined aquifer. WTAQ calculates theoretical time-drawdown curves for the pumped well and observation wells and piezometers. The theoretical curves are used with measured time-drawdown data to estimate hydraulic parameters of confined or unconfined aquifers by graphical type-curve methods or by automatic parameter-estimation methods. Parameters that can be estimated are horizontal and vertical hydraulic conductivity, specific storage, and specific yield. A sample application illustrates use of WTAQ for estimating hydraulic parameters of a hypothetical, unconfined aquifer by type-curve methods. Copyright ASCE 2004.

An overview of nitrate sources and operating processes in arid and semiarid aquifer systems.

Science.gov (United States)

Gutiérrez, Mélida; Biagioni, Richard N; Alarcón-Herrera, Maria Teresa; Rivas-Lucero, Bertha A

2018-05-15

Nitrate concentration in most aquifers in arid and semi-arid areas has increased in the past several decades as a result of human activities. Under the predominantly oxic conditions of these aquifers, denitrification is inhibited, allowing nitrate, a soluble and stable form of nitrogen (N), to accumulate. Because of its close association with municipal and agricultural wastes, nitrate is commonly used as an indicator of anthropogenic contamination. Aquifers affected by agricultural waste may contain salts from irrigation returns and herbicides in addition to nitrates. Preventing leakage from soil to deeper parts of the aquifer is thus a priority in the sustainable management of aquifers in arid and semiarid areas. Studies report a wide range of nitrate concentrations distributed non-uniformly within the aquifer, with roughly 40% and 20% of sampled wells exceeding 50mg/L nitrate in shallow and deep parts of the aquifer respectively. In aquifers at risk of becoming contaminated, nitrate isotopes (δ 15 N, δ 18 O, Δ 17 O) can be used to identify the source of nitrogen as mineral or organic fertilizer, sewage, or atmospheric deposition. A variety of mathematical models (crop, hydrological, geochemical, or a combination of them) have been successful in identifying best practices that minimize N leakage without negatively affecting crop yield. In addition, field research in crop management, e.g., conservation agriculture, has yielded promising results in determining the adequate dosage and time of application of fertilizers to reduce N losses. Examples of key dryland aquifers impacted by nitrate are discussed, and some of the most pressing challenges to achieve sustainability are presented. Copyright © 2017 Elsevier B.V. All rights reserved.

Geochemistry of the Arbuckle-Simpson Aquifer

Science.gov (United States)

Christenson, Scott; Hunt, Andrew G.; Parkhurst, David L.; Osborn, Noel I.

2009-01-01

The Arbuckle-Simpson aquifer in south-central Oklahoma provides water for public supply, farms, mining, wildlife conservation, recreation, and the scenic beauty of springs, streams, and waterfalls. A new understanding of the aquifer flow system was developed as part of the Arbuckle-Simpson Hydrology Study, done in 2003 through 2008 as a collaborative research project between the State of Oklahoma and the Federal government. The U.S. Geological Survey collected 36 water samples from 32 wells and springs in the Arbuckle-Simpson aquifer in 2004 through 2006 for geochemical analyses of major ions, trace elements, isotopes of oxygen and hydrogen, dissolved gases, and dating tracers. The geochemical analyses were used to characterize the water quality in the aquifer, to describe the origin and movement of ground water from recharge areas to discharge at wells and springs, and to determine the age of water in the aquifer.

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

Source, variability, and transformation of nitrate in a regional karst aquifer: Edwards aquifer, central Texas

Energy Technology Data Exchange (ETDEWEB)

Musgrove, M., E-mail: mmusgrov@usgs.gov [U.S. Geological Survey, 1505 Ferguson Lane, Austin, TX 78754 (United States); Opsahl, S.P. [U.S. Geological Survey, 5563 DeZavala, Ste. 290, San Antonio, TX 78249 (United States); Mahler, B.J. [U.S. Geological Survey, 1505 Ferguson Lane, Austin, TX 78754 (United States); Herrington, C. [City of Austin Watershed Protection Department, Austin, TX 78704 (United States); Sample, T.L. [U.S. Geological Survey, 19241 David Memorial Dr., Ste. 180, Conroe, TX 77385 (United States); Banta, J.R. [U.S. Geological Survey, 5563 DeZavala, Ste. 290, San Antonio, TX 78249 (United States)

2016-10-15

Many karst regions are undergoing rapid population growth and expansion of urban land accompanied by increases in wastewater generation and changing patterns of nitrate (NO{sub 3}{sup −}) loading to surface and groundwater. We investigate variability and sources of NO{sub 3}{sup −} in a regional karst aquifer system, the Edwards aquifer of central Texas. Samples from streams recharging the aquifer, groundwater wells, and springs were collected during 2008–12 from the Barton Springs and San Antonio segments of the Edwards aquifer and analyzed for nitrogen (N) species concentrations and NO{sub 3}{sup −} stable isotopes (δ{sup 15}N and δ{sup 18}O). These data were augmented by historical data collected from 1937 to 2007. NO{sub 3}{sup −} concentrations and discharge data indicate that short-term variability (days to months) in groundwater NO{sub 3}{sup −} concentrations in the Barton Springs segment is controlled by occurrence of individual storms and multi-annual wet-dry cycles, whereas the lack of short-term variability in groundwater in the San Antonio segment indicates the dominance of transport along regional flow paths. In both segments, longer-term increases (years to decades) in NO{sub 3}{sup −} concentrations cannot be attributed to hydrologic conditions; rather, isotopic ratios and land-use change indicate that septic systems and land application of treated wastewater might be the source of increased loading of NO{sub 3}{sup −}. These results highlight the vulnerability of karst aquifers to NO{sub 3}{sup −} contamination from urban wastewater. An analysis of N-species loading in recharge and discharge for the Barton Springs segment during 2008–10 indicates an overall mass balance in total N, but recharge contains higher concentrations of organic N and lower concentrations of NO{sub 3}{sup −} than does discharge, consistent with nitrification of organic N within the aquifer and consumption of dissolved oxygen. This study demonstrates

Source, variability, and transformation of nitrate in a regional karst aquifer: Edwards aquifer, central Texas

International Nuclear Information System (INIS)

Musgrove, M.; Opsahl, S.P.; Mahler, B.J.; Herrington, C.; Sample, T.L.; Banta, J.R.

2016-01-01

Many karst regions are undergoing rapid population growth and expansion of urban land accompanied by increases in wastewater generation and changing patterns of nitrate (NO 3 − ) loading to surface and groundwater. We investigate variability and sources of NO 3 − in a regional karst aquifer system, the Edwards aquifer of central Texas. Samples from streams recharging the aquifer, groundwater wells, and springs were collected during 2008–12 from the Barton Springs and San Antonio segments of the Edwards aquifer and analyzed for nitrogen (N) species concentrations and NO 3 − stable isotopes (δ 15 N and δ 18 O). These data were augmented by historical data collected from 1937 to 2007. NO 3 − concentrations and discharge data indicate that short-term variability (days to months) in groundwater NO 3 − concentrations in the Barton Springs segment is controlled by occurrence of individual storms and multi-annual wet-dry cycles, whereas the lack of short-term variability in groundwater in the San Antonio segment indicates the dominance of transport along regional flow paths. In both segments, longer-term increases (years to decades) in NO 3 − concentrations cannot be attributed to hydrologic conditions; rather, isotopic ratios and land-use change indicate that septic systems and land application of treated wastewater might be the source of increased loading of NO 3 − . These results highlight the vulnerability of karst aquifers to NO 3 − contamination from urban wastewater. An analysis of N-species loading in recharge and discharge for the Barton Springs segment during 2008–10 indicates an overall mass balance in total N, but recharge contains higher concentrations of organic N and lower concentrations of NO 3 − than does discharge, consistent with nitrification of organic N within the aquifer and consumption of dissolved oxygen. This study demonstrates that subaqueous nitrification of organic N in the aquifer, as opposed to in soils, might be a

Arsenic pollution of groundwater in Vietnam exacerbated by deep aquifer exploitation for more than a century

Science.gov (United States)

Winkel, Lenny H. E.; Trang, Pham Thi Kim; Lan, Vi Mai; Stengel, Caroline; Amini, Manouchehr; Ha, Nguyen Thi; Viet, Pham Hung; Berg, Michael

2011-01-01

Arsenic contamination of shallow groundwater is among the biggest health threats in the developing world. Targeting uncontaminated deep aquifers is a popular mitigation option although its long-term impact remains unknown. Here we present the alarming results of a large-scale groundwater survey covering the entire Red River Delta and a unique probability model based on three-dimensional Quaternary geology. Our unprecedented dataset reveals that ∼7 million delta inhabitants use groundwater contaminated with toxic elements, including manganese, selenium, and barium. Depth-resolved probabilities and arsenic concentrations indicate drawdown of arsenic-enriched waters from Holocene aquifers to naturally uncontaminated Pleistocene aquifers as a result of > 100 years of groundwater abstraction. Vertical arsenic migration induced by large-scale pumping from deep aquifers has been discussed to occur elsewhere, but has never been shown to occur at the scale seen here. The present situation in the Red River Delta is a warning for other As-affected regions where groundwater is extensively pumped from uncontaminated aquifers underlying high arsenic aquifers or zones. PMID:21245347

Fate of Arsenic during Red River Water Infiltration into Aquifers beneath Hanoi, Vietnam.

Science.gov (United States)

Postma, Dieke; Mai, Nguyen Thi Hoa; Lan, Vi Mai; Trang, Pham Thi Kim; Sø, Helle Ugilt; Nhan, Pham Quy; Larsen, Flemming; Viet, Pham Hung; Jakobsen, Rasmus

2017-01-17

Recharge of Red River water into arsenic-contaminated aquifers below Hanoi was investigated. The groundwater age at 40 m depth in the aquifer underlying the river was 1.3 ± 0.8 years, determined by tritium-helium dating. This corresponds to a vertical flow rate into the aquifer of 19 m/year. Electrical conductivity and partial pressure of CO 2 (P CO 2 ) indicate that water recharged from the river is present in both the sandy Holocene and gravelly Pleistocene aquifers and is also abstracted by the pumping station. Infiltrating river water becomes anoxic in the uppermost aquifer due to the oxidation of dissolved organic carbon. Further downward, sedimentary carbon oxidation causes the reduction of As-containing Fe-oxides. Because the release of arsenic by reduction of Fe-oxides is controlled by the reaction rate, arsenic entering the solution becomes highly diluted in the high water flux and contributes little to the groundwater arsenic concentration. Instead, the As concentration in the groundwater of up to 1 μM is due to equilibrium-controlled desorption of arsenic, adsorbed to the sediment before river water started to infiltrate due to municipal pumping. Calculations indicate that it will take several decades of river water infiltration to leach arsenic from the Holocene aquifer to below the World Health Organization limit of 10 μg/L.

Fate of Arsenic during Red River Water Infiltration into Aquifers beneath Hanoi, Vietnam

Science.gov (United States)

2016-01-01

Recharge of Red River water into arsenic-contaminated aquifers below Hanoi was investigated. The groundwater age at 40 m depth in the aquifer underlying the river was 1.3 ± 0.8 years, determined by tritium–helium dating. This corresponds to a vertical flow rate into the aquifer of 19 m/year. Electrical conductivity and partial pressure of CO2 (PCO2) indicate that water recharged from the river is present in both the sandy Holocene and gravelly Pleistocene aquifers and is also abstracted by the pumping station. Infiltrating river water becomes anoxic in the uppermost aquifer due to the oxidation of dissolved organic carbon. Further downward, sedimentary carbon oxidation causes the reduction of As-containing Fe-oxides. Because the release of arsenic by reduction of Fe-oxides is controlled by the reaction rate, arsenic entering the solution becomes highly diluted in the high water flux and contributes little to the groundwater arsenic concentration. Instead, the As concentration in the groundwater of up to 1 μM is due to equilibrium-controlled desorption of arsenic, adsorbed to the sediment before river water started to infiltrate due to municipal pumping. Calculations indicate that it will take several decades of river water infiltration to leach arsenic from the Holocene aquifer to below the World Health Organization limit of 10 μg/L. PMID:27958705

Adaptations of indigenous bacteria to fuel contamination in karst aquifers in south-central Kentucky

Science.gov (United States)

Byl, Thomas D.; Metge, David W.; Agymang, Daniel T.; Bradley, Michael W.; Hileman, Gregg; Harvey, Ronald W.

2014-01-01

The karst aquifer systems in southern Kentucky can be dynamic and quick to change. Microorganisms that live in these unpredictable aquifers are constantly faced with environmental changes. Their survival depends upon adaptations to changes in water chemistry, taking advantage of positive stimuli and avoiding negative environmental conditions. The U.S. Geological Survey conducted a study in 2001 to determine the capability of bacteria to adapt in two distinct regions of water quality in a karst aquifer, an area of clean, oxygenated groundwater and an area where the groundwater was oxygen depleted and contaminated by jet fuel. Water samples containing bacteria were collected from one clean well and two jet fuel contaminated wells in a conduit-dominated karst aquifer. Bacterial concentrations, enumerated through direct count, ranged from 500,000 to 2.7 million bacteria per mL in the clean portion of the aquifer, and 200,000 to 3.2 million bacteria per mL in the contaminated portion of the aquifer over a twelve month period. Bacteria from the clean well ranged in size from 0.2 to 2.5 mm, whereas bacteria from one fuel-contaminated well were generally larger, ranging in size from 0.2 to 3.9 mm. Also, bacteria collected from the clean well had a higher density and, consequently, were more inclined to sink than bacteria collected from contaminated wells. Bacteria collected from the clean portion of the karst aquifer were predominantly (,95%) Gram-negative and more likely to have flagella present than bacteria collected from the contaminated wells, which included a substantial fraction (,30%) of Gram-positive varieties. The ability of the bacteria from the clean portion of the karst aquifer to biodegrade benzene and toluene was studied under aerobic and anaerobic conditions in laboratory microcosms. The rate of fuel biodegradation in laboratory studies was approximately 50 times faster under aerobic conditions as compared to anaerobic, sulfur-reducing conditions. The

Hydrogeology of the Cambrian-Ordovician aquifer system in the northern Midwest: B in Regional aquifer-system analysis

Science.gov (United States)

Young, H.L.; Siegel, D.I.

1992-01-01

The Cambrian-Ordovician aquifer system contains the most extensive and continuous aquifers in the northern Midwest of the United States. It is the source of water for many municipalities, industries, and rural water users. Since the beginning of ground-water development from the aquifer system in the late 1800's, hydraulic heads have declined hundreds of feet in the heavily pumped Chicago-Milwaukee area and somewhat less in other metropolitan areas. The U.S. Geological Survey has completed a regional assessment of this aquifer system within a 161,000-square-mile area encompassing northern Illinois, northwestern Indiana, Iowa, southeastern Minnesota, northern Missouri, and Wisconsin.

Groundwater movement, recharge, and perchlorate occurrence in a faulted alluvial aquifer in California (USA)

Science.gov (United States)

Izbicki, John A.; Teague, Nicholas F.; Hatzinger, Paul B.; Böhlke, John Karl; Sturchio, Neil C.

2015-01-01

Perchlorate from military, industrial, and legacy agricultural sources is present within an alluvial aquifer in the Rialto-Colton groundwater subbasin, 80 km east of Los Angeles, California (USA). The area is extensively faulted, with water-level differences exceeding 60 m across parts of the Rialto-Colton Fault separating the Rialto-Colton and Chino groundwater subbasins. Coupled well-bore flow and depth-dependent water-quality data show decreases in well yield and changes in water chemistry and isotopic composition, reflecting changing aquifer properties and groundwater recharge sources with depth. Perchlorate movement through some wells under unpumped conditions from shallower to deeper layers underlying mapped plumes was as high as 13 kg/year. Water-level maps suggest potential groundwater movement across the Rialto-Colton Fault through an overlying perched aquifer. Upward flow through a well in the Chino subbasin near the Rialto-Colton Fault suggests potential groundwater movement across the fault through permeable layers within partly consolidated deposits at depth. Although potentially important locally, movement of groundwater from the Rialto-Colton subbasin has not resulted in widespread occurrence of perchlorate within the Chino subbasin. Nitrate and perchlorate concentrations at the water table, associated with legacy agricultural fertilizer use, may be underestimated by data from long-screened wells that mix water from different depths within the aquifer.

Contamination in fractured-rock aquifers: Research at the former Naval Air Warfare Center, West Trenton, New Jersey

Science.gov (United States)

Goode, Daniel J.; Tiedeman, Claire; Lacombe, Pierre J.; Imbrigiotta, Thomas E.; Shapiro, Allen M.; Chapelle, Francis H.

2007-01-01

The U.S. Geological Survey and cooperators are studying chlorinated solvents in a fractured sedimentary rock aquifer underlying the former Naval Air Warfare Center (NAWC), West Trenton, New Jersey. Fractured-rock aquifers are common in many parts of the United States and are highly susceptible to contamination, particularly at industrial sites. Compared to 'unconsolidated' aquifers, there can be much more uncertainty about the direction and rate of contaminant migration and about the processes and factors that control chemical and microbial transformations of contaminants. Research at the NAWC is improving understanding of the transport and fate of chlorinated solvents in fractured-rock aquifers and will compare the effectiveness of different strategies for contaminant remediation.

Aquifer geochemistry at potential aquifer storage and recovery sites in coastal plain aquifers in the New York city area, USA

Science.gov (United States)

Brown, C.J.; Misut, P.E.

2010-01-01

The effects of injecting oxic water from the New York city (NYC) drinking-water supply and distribution system into a nearby anoxic coastal plain aquifer for later recovery during periods of water shortage (aquifer storage and recovery, or ASR) were simulated by a 3-dimensional, reactive-solute transport model. The Cretaceous aquifer system in the NYC area of New York and New Jersey, USA contains pyrite, goethite, locally occurring siderite, lignite, and locally varying amounts of dissolved Fe and salinity. Sediment from cores drilled on Staten Island and western Long Island had high extractable concentrations of Fe, Mn, and acid volatile sulfides (AVS) plus chromium-reducible sulfides (CRS) and low concentrations of As, Pb, Cd, Cr, Cu and U. Similarly, water samples from the Lloyd aquifer (Cretaceous) in western Long Island generally contained high concentrations of Fe and Mn and low concentrations of other trace elements such as As, Pb, Cd, Cr, Cu and U, all of which were below US Environmental Protection Agency (USEPA) and NY maximum contaminant levels (MCLs). In such aquifer settings, ASR operations can be complicated by the oxidative dissolution of pyrite, low pH, and high concentrations of dissolved Fe in extracted water.The simulated injection of buffered, oxic city water into a hypothetical ASR well increased the hydraulic head at the well, displaced the ambient groundwater, and formed a spheroid of injected water with lower concentrations of Fe, Mn and major ions in water surrounding the ASR well, than in ambient water. Both the dissolved O2 concentrations and the pH of water near the well generally increased in magnitude during the simulated 5-a injection phase. The resultant oxidation of Fe2+ and attendant precipitation of goethite during injection provided a substrate for sorption of dissolved Fe during the 8-a extraction phase. The baseline scenario with a low (0.001M) concentration of pyrite in aquifer sediments, indicated that nearly 190% more water

Hydrochemistry of New Zealand's aquifers

International Nuclear Information System (INIS)

Rosen, M.R.

2001-01-01

taken from regional authority 'State of the Environment' reports and from detailed reports on central Canterbury. The chapter summarises the major element chemistry and relates this to aquifer geology and land use. Nutrient chemistry and an analysis of some heavy metals are also included and this information is related to land use. Pesticides and nitrate are discussed in Chapter 8 and nitrate is only briefly mentioned here under nutrients. A brief discussion of hydrocarbons and other organic chemicals is included for areas that have available data, but a discussion of microbial contamination of groundwater is reserved for Chapter 9. (author). 53 refs., 18 figs., 4 tabs

Piezometric level and electrical conductivity spatiotemporal monitoring as an instrument to design further managed aquifer recharge strategies in a complex estuarial system under anthropogenic pressure.

Science.gov (United States)

Coelho, Victor Hugo R; Bertrand, Guillaume F; Montenegro, Suzana M G L; Paiva, Anderson L R; Almeida, Cristiano N; Galvão, Carlos O; Barbosa, Luís Romero; Batista, Larissa F D R; Ferreira, Eduardo L G A

2018-03-01

Recife Metropolitan Region (RMR, NE Brazil) lies over a multi-layered aquifer system located in an estuarial area. The region has experienced fast population growth and repeated droughts in the last three decades, which led to unprecedented anthropogenic pressure on groundwater resources because of intense water pumping. Accordingly, scientific and stakeholder communities have been challenged to ensure the maintenance of sustainable groundwater resource by managing all water cycle. Because controlling pumping rates is difficult due to the large number of illegal wells, the Managed Aquifer Recharge (MAR) strategies are now under consideration. The RMR presents a tropical climate and an annual average rainfall rate of approximately 2450 mm year -1 , providing great potential volumes of water to be used for piezometric level recovery. However, MAR implementation requires a detailed and in-depth knowledge of the human-impact on the hydrogeological behavior of the resource over the long-term, in order to find out the most appropriate recharge strategy. Therefore, the present study illustrates how routine data monitoring, i.e., piezometric level and electrical conductivity (EC), in combination with the geological knowledge, may allow proposing further MAR strategies. Two contrasted behaviors were observed in RMR: (i) groundwater level decrease and stable EC in the North and Southernmost areas of Recife; and (ii) stable groundwater level and high/varying EC values next to the estuarial zone. Although aquifers are undergoing over-abstraction, this spatiotemporal heterogeneity suggests that a recharge is possibly locally favored next to the estuarial area of the RMR thanks to hydraulic connections between surface and deep aquifers throughout extended paleo-channels. Thus, based on this typology, MAR implementation through controlled infiltration close to the estuarial area seems to be more appropriated, whereas the direct deep injection appears to be more relevant in more

Hydrology of the shallow aquifer and uppermost semiconfined aquifer near El Paso, Texas

Science.gov (United States)

White, D.E.; Baker, E.T.; Sperka, Roger

1997-01-01

The availability of fresh ground water in El Paso and adjacent areas that is needed to meet increased demand for water supply concerns local, State, and Federal agencies. The Hueco bolson is the principal aquifer in the El Paso area. Starting in the early 1900s and continuing to the 1950s, most of the municipal and industrial water supply in El Paso was pumped from the Hueco bolson aquifer from wells in and near the Rio Grande Valley and the international border. The Rio Grande is the principal surface-water feature in the El Paso area, and a major source of recharge to the shallow aquifer (Rio Grande alluvium) within the study area is leakage of flow from the Rio Grande.

Sustainability of natural attenuation of nitrate in agricultural aquifers

Science.gov (United States)

Green, Christopher T.; Bekins, Barbara A.

2010-01-01

Increased concentrations of nitrate in groundwater in agricultural areas, coinciding with increased use of chemical and organic fertilizers, have raised concern because of risks to environmental and human health. At some sites, these problems are mitigated by natural attenuation of nitrate as a result of microbially mediated reactions. Results from U.S. Geological Survey (USGS) research under the National Water-Quality Assessment (NAWQA) program show that reactions of dissolved nitrate with solid aquifer minerals and organic carbon help lower nitrate concentrations in groundwater beneath agricultural fields. However, increased fluxes of nitrate cause ongoing depletion of the finite pool of solid reactants. Consumption of the solid reactants diminishes the capacity of the aquifer to remove nitrate, calling into question the long-term sustainability of these natural attenuation processes.

Salinization in a stratified aquifer induced by heat transfer from well casings

Science.gov (United States)

van Lopik, Jan H.; Hartog, Niels; Zaadnoordijk, Willem Jan; Cirkel, D. Gijsbert; Raoof, Amir

2015-12-01

The temperature inside wells used for gas, oil and geothermal energy production, as well as steam injection, is in general significantly higher than the groundwater temperature at shallower depths. While heat loss from these hot wells is known to occur, the extent to which this heat loss may result in density-driven flow and in mixing of surrounding groundwater has not been assessed so far. However, based on the heat and solute effects on density of this arrangement, the induced temperature contrasts in the aquifer due to heat transfer are expected to destabilize the system and result in convection, while existing salt concentration contrasts in an aquifer would act to stabilize the system. To evaluate the degree of impact that may occur under field conditions, free convection in a 50-m-thick aquifer driven by the heat loss from penetrating hot wells was simulated using a 2D axisymmetric SEAWAT model. In particular, the salinization potential of fresh groundwater due to the upward movement of brackish or saline water in a stratified aquifer is studied. To account for a large variety of well applications and configurations, as well as different penetrated aquifer systems, a wide range of well temperatures, from 40 to 100 °C, together with a range of salt concentration (1-35 kg/m3) contrasts were considered. This large temperature difference with the native groundwater (15 °C) required implementation of a non-linear density equation of state in SEAWAT. We show that density-driven groundwater flow results in a considerable salt mass transport (up to 166,000 kg) to the top of the aquifer in the vicinity of the well (radial distance up to 91 m) over a period of 30 years. Sensitivity analysis showed that density-driven groundwater flow and the upward salt transport was particularly enhanced by the increased heat transport from the well into the aquifer by thermal conduction due to increased well casing temperature, thermal conductivity of the soil, as well as decreased

Methyl tert-butyl ether biodegradation by indigenous aquifer microorganisms under natural and artificial oxic conditions

Science.gov (United States)

Landmeyer, J.E.; Chapelle, F.H.; Herlong, H.H.; Bradley, P.M.

2001-01-01

Microbial communities indigenous to a shallow groundwater system near Beaufort, SC, degraded milligram per liter concentrations of methyl tert-butyl ether (MTBE) under natural and artificial oxic conditions. Significant MTBE biodegradation was observed where anoxic, MTBE-contaminated groundwater discharged to a concrete-lined ditch. In the anoxic groundwater adjacent to the ditch, concentrations of MTBE were > 1 mg/L. Where groundwater discharge occurs, dissolved oxygen (DO) concentrations beneath the ditch exceeded 1.0 mg/L to a depth of 1.5 m, and MTBE concentrations decreased to CO2 in laboratory liquid culture studies, with no accumulation of intermediate compounds. Upgradient of the ditch in the anoxic, MTBE and BTEX-contaminated aquifer, addition of a soluble oxygen release compound resulted in oxic conditions and rapid MTBE biodegradation by indigenous microorganisms. In an observation well located closest to the oxygen addition area, DO concentrations increased from 0.4 to 12 mg/L in <60 days and MTBE concentrations decreased from 20 to 3 mg/L. In the same time period at a downgradient observation well, DO increased from <0.2 to 2 mg/L and MTBE concentrations decreased from 30 to <5 mg/L. These results indicate that microorganisms indigenous to the groundwater system at this site can degrade milligram per liter concentrations of MTBE under natural and artificial oxic conditions.

Comparison of dissolved and particulate arsenic distributions in shallow aquifers of Chakdaha, India, and Araihazar, Bangladesh

Directory of Open Access Journals (Sweden)

Ahmed Kazi M

2008-01-01

Full Text Available Abstract Background The origin of the spatial variability of dissolved As concentrations in shallow aquifers of the Bengal Basin remains poorly understood. To address this, we compare here transects of simultaneously-collected groundwater and aquifer solids perpendicular to the banks of the Hooghly River in Chakdaha, India, and the Old Brahmaputra River in Araihazar, Bangladesh. Results Variations in surface geomorphology mapped by electromagnetic conductivity indicate that permeable sandy soils are associated with underlying aquifers that are moderately reducing to a depth of 10–30 m, as indicated by acid-leachable Fe(II/Fe ratios 5 mg L-1. More reducing aquifers are typically capped with finer-grained soils. The patterns suggest that vertical recharge through permeable soils is associated with a flux of oxidants on the banks of the Hooghly River and, further inland, in both Chakdaha and Araihazar. Moderately reducing conditions maintained by local recharge are generally associated with low As concentrations in Araihazar, but not systematically so in Chakdaha. Unlike Araihazar, there is also little correspondence in Chakdaha between dissolved As concentrations in groundwater and the P-extractable As content of aquifer particles, averaging 191 ± 122 ug As/L, 1.1 ± 1.5 mg As kg-1 (n = 43 and 108 ± 31 ug As/L, 3.1 ± 6.5 mg As kg-1 (n = 60, respectively. We tentatively attribute these differences to a combination of younger floodplain sediments, and therefore possibly more than one mechanism of As release, as well as less reducing conditions in Chakdaha compared to Araihazar. Conclusion Systematic dating of groundwater and sediment, combined with detailed mapping of the composition of aquifer solids and groundwater, will be needed to identify the various mechanisms underlying the complex distribution of As in aquifers of the Bengal Basin.

Cotton Water Use Efficiency under Two Different Deficit Irrigation Scheduling Methods

Directory of Open Access Journals (Sweden)

Jeffrey T. Baker

2015-08-01

Full Text Available Declines in Ogallala aquifer levels used for irrigation has prompted research to identify methods for optimizing water use efficiency (WUE of cotton (Gossypium hirsutum L. In this experiment, conducted at Lubbock, TX, USA in 2014, our objective was to test two canopy temperature based stress indices, each at two different irrigation trigger set points: the Stress Time (ST method with irrigation triggers set at 5.5 (ST_5.5 and 8.5 h (ST_8.5 and the Crop Water Stress Index (CWSI method with irrigation triggers set at 0.3 (CWSI_0.3 and 0.6 (CWSI_0.6. When these irrigation triggers were exceeded on a given day, the crop was deficit irrigated with 5 mm of water via subsurface drip tape. Also included in the experimental design were a well-watered (WW control irrigated at 110% of potential evapotranspiration and a dry land (DL treatment that relied on rainfall only. Seasonal crop water use ranged from 353 to 625 mm across these six treatments. As expected, cotton lint yield increased with increasing crop water use but lint yield WUE displayed asignificant (p ≤ 0.05 peak near 3.6 to 3.7 kg ha−1 mm−1 for the ST_5.5 and CWSI_0.3 treatments, respectively. Our results suggest that WUE may be optimized in cotton with less water than that needed for maximum lint yield.

Water Decisions for Sustainability of the Arbuckle-Simpson Aquifer

Science.gov (United States)

Lazrus, H.; Mcpherson, R. A.; Morss, R. E.; PaiMazumder, D.; Silvis, V.; Towler, E.

2012-12-01

The Arbuckle-Simpson Aquifer in south-central Oklahoma, situated in the heart of the Chickasaw Nation, is the state's only sole-source groundwater basin and sustains the Blue River, the state's only freeflowing river. The recent comprehensive hydrological studies of the aquifer indicate the need for sustainable management of the amount of water extracted. However, the question of how to deal with that management in the face of increasing drought vulnerability, diverse demands, and climate variability and change remains. Water management carries a further imperative to be inclusive of tribal and non-tribal interests. To address these issues, this interdisciplinary project takes an integrated approach to understanding risk perceptions and water decisions for sustainability of the Arbuckle-Simpson Aquifer. Our interdisciplinary research asks: How do stakeholders in the Arbuckle-Simpson Aquifer perceive drought risks across weather and climate scales, and how do these perceptions guide water management decisions given (i) diverse cultural beliefs, (ii) valued hydrologic services, (iii) past drought experience, and (iv) uncertainties in future projection of precipitation and drought? We will use ethnographic methods to diagnose how cultural values and beliefs inform risk perceptions, and how this in turn guides decision making or ignites conflict across different sectors and stakeholder groups. Further, the characterization of drought risk will be examined in the context of historic meteorological and hydrologic events, as well as climate variability and change. This will identify which risks are prioritized, and under what conditions, in regional decision making or water-related conflicts.

Estimating the Spatial Extent of Unsaturated Zones in Heterogeneous River-Aquifer Systems

Science.gov (United States)

Schilling, Oliver S.; Irvine, Dylan J.; Hendricks Franssen, Harrie-Jan; Brunner, Philip

2017-12-01

The presence of unsaturated zones at the river-aquifer interface has large implications on numerous hydraulic and chemical processes. However, the hydrological and geological controls that influence the development of unsaturated zones have so far only been analyzed with simplified conceptualizations of flow processes, or homogeneous conceptualizations of the hydraulic conductivity in either the aquifer or the riverbed. We systematically investigated the influence of heterogeneous structures in both the riverbed and the aquifer on the development of unsaturated zones. A stochastic 1-D criterion that takes both riverbed and aquifer heterogeneity into account was developed using a Monte Carlo sampling technique. The approach allows the reliable estimation of the upper bound of the spatial extent of unsaturated areas underneath a riverbed. Through systematic numerical modeling experiments, we furthermore show that horizontal capillary forces can reduce the spatial extent of unsaturated zones under clogged areas. This analysis shows how the spatial structure of clogging layers and aquifers influence the propensity for unsaturated zones to develop: In riverbeds where clogged areas are made up of many small, spatially disconnected patches with a diameter in the order of 1 m, unsaturated areas are less likely to develop compared to riverbeds where large clogged areas exist adjacent to unclogged areas. A combination of the stochastic 1-D criterion with an analysis of the spatial structure of the clogging layers and the potential for resaturation can help develop an appropriate conceptual model and inform the choice of a suitable numerical simulator for river-aquifer systems.

AQUIFER IN AJAOKUTA, SOUTHWESTERN NIGERIA

African Journals Online (AJOL)

2005-03-08

Mar 8, 2005 ... To establish the feasibility of water supply in a basement complex area ofAjaokuta, Southwestern Nigeria, pumping test results were used to investigate the storage properties and groundwater potential of the aquifer. The aquifer system consists of weathered and weathered/fractured zone of decomposed ...

Hydrological controls on transient aquifer storage in a karst watershed

Science.gov (United States)

Spellman, P.; Martin, J.; Gulley, J. D.

2017-12-01

While surface storage of floodwaters is well-known to attenuate flood peaks, transient storage of floodwaters in aquifers is a less recognized mechanism of flood peak attenuation. The hydraulic gradient from aquifer to river controls the magnitude of transient aquifer storage and is ultimately a function of aquifer hydraulic conductivity, and effective porosity. Because bedrock and granular aquifers tend to have lower hydraulic conductivities and porosities, their ability to attenuate flood peaks is generally small. In karst aquifers, however, extensive cave systems create high hydraulic conductivities and porosities that create low antecedent hydraulic gradients between aquifers and rivers. Cave springs can reverse flow during high discharges in rivers, temporarily storing floodwaters in the aquifer thus reducing the magnitude of flood discharge downstream. To date however, very few studies have quantified the magnitude or controls of transient aquifer storage in karst watersheds. We therefore investigate controls on transient aquifer storage by using 10 years of river and groundwater data from the Suwannee River Basin, which flows over the karstic upper Floridan aquifer in north-central Florida. We use multiple linear regression to compare the effects of three hydrological controls on the magnitude of transient aquifer storage: antecedent stage, recharge and slope of hydrograph rise. We show the dominant control on transient aquifer storage is antecedent stage, whereby lower stages result in greater magnitudes of transient aquifer storage. Our results suggest that measures of groundwater levels prior to an event can be useful in determining whether transient aquifer storage will occur and may provide a useful metric for improving predictions of flood magnitudes.

Potential impacts of leakage from deep CO2 geosequestration on overlying freshwater aquifers.

Science.gov (United States)

Little, Mark G; Jackson, Robert B

2010-12-01

Carbon Capture and Storage may use deep saline aquifers for CO(2) sequestration, but small CO(2) leakage could pose a risk to overlying fresh groundwater. We performed laboratory incubations of CO(2) infiltration under oxidizing conditions for >300 days on samples from four freshwater aquifers to 1) understand how CO(2) leakage affects freshwater quality; 2) develop selection criteria for deep sequestration sites based on inorganic metal contamination caused by CO(2) leaks to shallow aquifers; and 3) identify geochemical signatures for early detection criteria. After exposure to CO(2), water pH declines of 1-2 units were apparent in all aquifer samples. CO(2) caused concentrations of the alkali and alkaline earths and manganese, cobalt, nickel, and iron to increase by more than 2 orders of magnitude. Potentially dangerous uranium and barium increased throughout the entire experiment in some samples. Solid-phase metal mobility, carbonate buffering capacity, and redox state in the shallow overlying aquifers influence the impact of CO(2) leakage and should be considered when selecting deep geosequestration sites. Manganese, iron, calcium, and pH could be used as geochemical markers of a CO(2) leak, as their concentrations increase within 2 weeks of exposure to CO(2).

Aquifer depletion in the Lower Mississippi River Basin: challenges and solutions

Science.gov (United States)

The Lower Mississippi River Basin (LMRB) is a nationally- and internationally-important region of intensive agricultural production that relies heavily on the underlying Mississippi River Valley Alluvial Aquifer (MRVAA) for row crop irrigation. Extensive irrigation coupled with the region’s geology ...

Hydrogeology - AQUIFER_SYSTEMS_BEDROCK_IDNR_IN: Bedrock Aquifer Systems of Indiana (Indiana Department of Natural Resources, 1:500,000, Polygon Shapefile)

Data.gov (United States)

NSGIC State | GIS Inventory — AQUIFER_SYSTEMS_BEDROCK_IDNR_IN is a polygon shapefile that shows bedrock aquifer systems of the State of Indiana. The source scale of the map depicting the aquifers...

Groundwater recharge and chemical evolution in the southern High Plains of Texas, USA

Science.gov (United States)

Fryar, Alan; Mullican, William; Macko, Stephen

2001-11-01

The unconfined High Plains (Ogallala) aquifer is the largest aquifer in the USA and the primary water supply for the semiarid southern High Plains of Texas and New Mexico. Analyses of water and soils northeast of Amarillo, Texas, together with data from other regional studies, indicate that processes during recharge control the composition of unconfined groundwater in the northern half of the southern High Plains. Solute and isotopic data are consistent with a sequence of episodic precipitation, concentration of solutes in upland soils by evapotranspiration, runoff, and infiltration beneath playas and ditches (modified locally by return flow of wastewater and irrigation tailwater). Plausible reactions during recharge include oxidation of organic matter, dissolution and exsolution of CO2, dissolution of CaCO3, silicate weathering, and cation exchange. Si and 14C data suggest leakage from perched aquifers to the High Plains aquifer. Plausible mass-balance models for the High Plains aquifer include scenarios of flow with leakage but not reactions, flow with reactions but not leakage, and flow with neither reactions nor leakage. Mechanisms of recharge and chemical evolution delineated in this study agree with those noted for other aquifers in the south-central and southwestern USA. Résumé. L'aquifère libre des Hautes Plaines (Ogallala) est le plus vaste aquifère des états-Unis et la ressource de base pour l'eau potable de la région semi-aride du sud des Hautes Plaines du Texas et du Nouveau-Mexique. Des analyses de l'eau et des sols prélevés au nord-est d'Amarillo (Texas), associées à des données provenant d'autres études dans cette région, indiquent que des processus intervenant au cours de l'infiltration contrôlent la composition de l'eau de la nappe libre dans la moitié septentrionale du sud des Hautes Plaines. Les données chimiques et isotopiques sont compatibles avec une séquence de précipitation épisodique, avec la reconcentration en solut

Source, variability, and transformation of nitrate in a regional karst aquifer: Edwards aquifer, central Texas.

Science.gov (United States)

Musgrove, MaryLynn; Opsahl, Stephen P.; Mahler, Barbara J.; Herrington, Chris; Sample, Thomas; Banta, John

2016-01-01

Many karst regions are undergoing rapid population growth and expansion of urban land accompanied by increases in wastewater generation and changing patterns of nitrate (NO3−) loading to surface and groundwater. We investigate variability and sources of NO3− in a regional karst aquifer system, the Edwards aquifer of central Texas. Samples from streams recharging the aquifer, groundwater wells, and springs were collected during 2008–12 from the Barton Springs and San Antonio segments of the Edwards aquifer and analyzed for nitrogen (N) species concentrations and NO3− stable isotopes (δ15N and δ18O). These data were augmented by historical data collected from 1937 to 2007. NO3− concentrations and discharge data indicate that short-term variability (days to months) in groundwater NO3− concentrations in the Barton Springs segment is controlled by occurrence of individual storms and multi-annual wet-dry cycles, whereas the lack of short-term variability in groundwater in the San Antonio segment indicates the dominance of transport along regional flow paths. In both segments, longer-term increases (years to decades) in NO3− concentrations cannot be attributed to hydrologic conditions; rather, isotopic ratios and land-use change indicate that septic systems and land application of treated wastewater might be the source of increased loading of NO3−. These results highlight the vulnerability of karst aquifers to NO3− contamination from urban wastewater. An analysis of N-species loading in recharge and discharge for the Barton Springs segment during 2008–10 indicates an overall mass balance in total N, but recharge contains higher concentrations of organic N and lower concentrations of NO3−than does discharge, consistent with nitrification of organic N within the aquifer and consumption of dissolved oxygen. This study demonstrates that subaqueous nitrification of organic N in the aquifer, as opposed to in soils, might be a previously

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

Energy Technology Data Exchange (ETDEWEB)

Klukas, M H; Moltyaner, G L

1995-05-01

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

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

International Nuclear Information System (INIS)

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

1995-05-01

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

Simulated effects of projected pumping on the availability of freshwater in the Evangeline Aquifer in an area southwest of Corpus Christi, Texas

Science.gov (United States)

Groschen, George E.

1985-01-01

This study is an investigation of the continued availability of freshwater in the Evangeline aquifer along the Texas Gulf Coast and the potential for degradation of the water quality by salinewater intrusion. Recharge to the aquifer occurs by the infiltration of precipitation in the outcrop area and by cross-formational flow from deeper aquifers. The predevelopment recharge rate is about 6 to 8 cubic feet per second. The predevelopment flow is toward the coast. The flow is semiconfined in the outcrop area and confined underneath the Chicot aquifer in the eastern two-thirds of the study area. Discharge, under natural conditions, is upward into the Chicot aquifer and to the Nueces River or Gulf of Mexico. Intensive pumping by irrigators, industries, and municipalities over the last 80 years has created a cone of depression as deep as 219 feet below sea level under the city of Kingsville in Kleberg County. The total rate of pumpage in 1982 was 29.6 cubic feet per second.

Semi-analytical solution for flow in a leaky unconfined aquifer toward a partially penetrating pumping well

Science.gov (United States)

Malama, Bwalya; Kuhlman, Kristopher L.; Barrash, Warren

2008-07-01

SummaryA semi-analytical solution is presented for the problem of flow in a system consisting of unconfined and confined aquifers, separated by an aquitard. The unconfined aquifer is pumped continuously at a constant rate from a well of infinitesimal radius that partially penetrates its saturated thickness. The solution is termed semi-analytical because the exact solution obtained in double Laplace-Hankel transform space is inverted numerically. The solution presented here is more general than similar solutions obtained for confined aquifer flow as we do not adopt the assumption of unidirectional flow in the confined aquifer (typically assumed to be horizontal) and the aquitard (typically assumed to be vertical). Model predicted results show significant departure from the solution that does not take into account the effect of leakage even for cases where aquitard hydraulic conductivities are two orders of magnitude smaller than those of the aquifers. The results show low sensitivity to changes in radial hydraulic conductivities for aquitards that are two or more orders of magnitude smaller than those of the aquifers, in conformity to findings of earlier workers that radial flow in aquitards may be neglected under such conditions. Hence, for cases were aquitard hydraulic conductivities are two or more orders of magnitude smaller than aquifer conductivities, the simpler models that restrict flow to the radial direction in aquifers and to the vertical direction in aquitards may be sufficient. However, the model developed here can be used to model flow in aquifer-aquitard systems where radial flow is significant in aquitards.

Hydrogeologic framework of the uppermost principal aquifer systems in the Williston and Powder River structural basins, United States and Canada

Science.gov (United States)

Thamke, Joanna N.; LeCain, Gary D.; Ryter, Derek W.; Sando, Roy; Long, Andrew J.

2014-01-01

The glacial, lower Tertiary, and Upper Cretaceous aquifer systems in the Williston and Powder River structural basins within the United States and Canada are the uppermost principal aquifer systems and most accessible sources of groundwater for these energy-producing basins. The glacial aquifer system covers the northeastern part of the Williston structural basin. The lower Tertiary and Upper Cretaceous aquifer systems are present in about 91,300 square miles (mi2) of the Williston structural basin and about 25,500 mi2 of the Powder River structural basin. Directly under these aquifer systems are 800 to more than 3,000 feet (ft) of relatively impermeable marine shale that serves as a basal confining unit. The aquifer systems in the Williston structural basin have a shallow (less than 2,900 ft deep), wide, and generally symmetrical bowl shape. The aquifer systems in the Powder River structural basin have a very deep (as much as 8,500 ft deep), narrow, and asymmetrical shape.

Ground-water flow directions and estimation of aquifer hydraulic properties in the lower Great Miami River Buried Valley aquifer system, Hamilton Area, Ohio

Science.gov (United States)

Sheets, Rodney A.; Bossenbroek, Karen E.

2005-01-01

The Great Miami River Buried Valley Aquifer System is one of the most productive sources of potable water in the Midwest, yielding as much as 3,000 gallons per minute to wells. Many water-supply wells tapping this aquifer system are purposely placed near rivers to take advantage of induced infiltration from the rivers. The City of Hamilton's North Well Field consists of 10 wells near the Great Miami River, all completed in the lower Great Miami River Buried Valley Aquifer System. A well-drilling program and a multiple-well aquifer test were done to investigate ground-water flow directions and to estimate aquifer hydraulic properties in the lower part of the Great Miami River Buried Valley Aquifer System. Descriptions of lithology from 10 well borings indicate varying amounts and thickness of clay or till, and therefore, varying levels of potential aquifer confinement. Borings also indicate that the aquifer properties can change dramatically over relatively short distances. Grain-size analyses indicate an average bulk hydraulic conductivity value of aquifer materials of 240 feet per day; the geometric mean of hydraulic conductivity values of aquifer material was 89 feet per day. Median grain sizes of aquifer material and clay units were 1.3 millimeters and 0.1 millimeters, respectively. Water levels in the Hamilton North Well Field are affected by stream stage in the Great Miami River and barometric pressure. Bank storage in response to stream stage is evident. Results from a multiple-well aquifer test at the well field indicate, as do the lithologic descriptions, that the aquifer is semiconfined in some areas and unconfined in others. Transmissivity and storage coefficient of the semiconfined part of the aquifer were 50,000 feet squared per day and 5x10-4, respectively. The average hydraulic conductivity (450 feet per day) based on the aquifer test is reasonable for glacial outwash but is higher than calculated from grain-size analyses, implying a scale effect

Descriptions and characterizations of water-level data and groundwater flow for the Brewster Boulevard and Castle Hayne Aquifer Systems and the Tarawa Terrace Aquifer

Science.gov (United States)

Faye, Robert E.; Jones, L. Elliott; Suárez-Soto, René J.

2013-01-01

This supplement of Chapter A (Supplement 3) summarizes results of analyses of groundwater-level data and describes corresponding elements of groundwater flow such as vertical hydraulic gradients useful for groundwater-flow model calibration. Field data as well as theoretical concepts indicate that potentiometric surfaces within the study area are shown to resemble to a large degree a subdued replica of surface topography. Consequently, precipitation that infiltrates to the water table flows laterally from highland to lowland areas and eventually discharges to streams such as Northeast and Wallace Creeks and New River. Vertically downward hydraulic gradients occur in highland areas resulting in the transfer of groundwater from shallow relatively unconfined aquifers to underlying confined or semi-confined aquifers. Conversely, in the vicinity of large streams such as Wallace and Frenchs Creeks, diffuse upward leakage occurs from underlying confined or semi-confined aquifers. Point water-level data indicating water-table altitudes, water-table altitudes estimated using a regression equation, and estimates of stream levels determined from a digital elevation model (DEM) and topographic maps were used to estimate a predevelopment water-table surface in the study area. Approximate flow lines along hydraulic gradients are shown on a predevelopment potentiometric surface map and extend from highland areas where potentiometric levels are greatest toward streams such as Wallace Creek and Northeast Creek. The distribution of potentiometric levels and corresponding groundwater-flow directions conform closely to related descriptions of the conceptual model.

Hydrogeology and Aquifer Storage and Recovery Performance in the Upper Floridan Aquifer, Southern Florida

Science.gov (United States)

Reese, Ronald S.; Alvarez-Zarikian, Carlos A.

2007-01-01

Well construction, hydraulic well test, ambient water-quality, and cycle test data were inventoried and compiled for 30 aquifer storage and recovery facilities constructed in the Floridan aquifer system in southern Florida. Most of the facilities are operated by local municipalities or counties in coastal areas, but five sites are currently being evaluated as part of the Comprehensive Everglades Restoration Plan. The relative performance of all sites with adequate cycle test data was determined, and compared with four hydrogeologic and design factors that may affect recovery efficiency. Testing or operational cycles include recharge, storage, and recovery periods that each last days or months. Cycle test data calculations were made including the potable water (chloride concentration of less than 250 milligrams per liter) recovery efficiency per cycle, total recovery efficiency per cycle, and cumulative potable water recovery efficiencies for all of the cycles at each site. The potable water recovery efficiency is the percentage of the total amount of potable water recharged for each cycle that is recovered; potable water recovery efficiency calculations (per cycle and cumulative) were the primary measures used to evaluate site performance in this study. Total recovery efficiency, which is the percent recovery at the end of each cycle, however, can be substantially higher and is the performance measure normally used in the operation of water-treatment plants. The Upper Floridan aquifer of the Floridan aquifer system currently is being used, or planned for use, at 29 of the aquifer storage and recovery sites. The Upper Floridan aquifer is continuous throughout southern Florida, and its overlying confinement is generally good; however, the aquifer contains brackish to saline ground water that can greatly affect freshwater storage and recovery due to dispersive mixing within the aquifer. The hydrogeology of the Upper Floridan varies in southern Florida; confinement

Factors affecting public-supply well vulnerability in two karst aquifers.

Science.gov (United States)

Musgrove, MaryLynn; Katz, Brian G; Fahlquist, Lynne S; Crandall, Christy A; Lindgren, Richard J

2014-09-01

Karst aquifers occur in a range of climatic and geologic settings. Nonetheless, they are commonly characterized by their vulnerability to water-quality impairment. Two karst aquifers, the Edwards aquifer in south-central Texas and the Upper Floridan aquifer in western Florida, were investigated to assess factors that control the movement of contaminants to public-supply wells (PSWs). The geochemistry of samples from a selected PSW or wellfield in each aquifer was compared with that from nearby monitoring wells and regional PSWs. Geochemistry results were integrated with age tracers, flow modeling, and depth-dependent data to refine aquifer conceptual models and to identify factors that affect contaminant movement to PSWs. The oxic Edwards aquifer is vertically well mixed at the selected PSW/wellfield, although regionally the aquifer is geochemically variable downdip. The mostly anoxic Upper Floridan aquifer is affected by denitrification and also is geochemically variable with depth. In spite of considerable differences in geology and hydrogeology, the two aquifers are similarly vulnerable to anthropogenic contamination. Vulnerability in studied PSWs in both aquifers is strongly influenced by rapid karst flowpaths and the dominance of young (aquifers (nitrate, atrazine, deethylatrazine, tetrachloroethene, and chloroform). Specific consideration of water-quality protection efforts, well construction and placement, and aquifer response times to land-use changes and contaminant loading are discussed, with implications for karst groundwater management. © 2014 The Authors. Groundwater published by Wiley Periodicals, Inc. on behalf of National Ground Water Association.

Ozark Aquifer

Data.gov (United States)

Kansas Data Access and Support Center — These digital maps contain information on the altitude of the base and top, the extent, and the potentiometric surface of the Ozark aquifer in Kansas. The Ozark...

Characterization of Predominant Reductants in an Anaerobic Leachate-Contaminated Aquifer by Nitroaromatic Probe Compounds

DEFF Research Database (Denmark)

Rügge, Kirsten; Hofstetter, Thomas B.; Haderlein, Stefan B.

1998-01-01

The biogeochemical processes controlling the reductive transformation of contaminants in an anaerobic aquifer were inferred from the relative reactivity patterns of redox-sensitive probe compounds. The fate of five nitroaromatic compounds (NACs) was monitored under different redox conditions in a...... results suggest that Fe(ll) associated with ferric iron minerals is a highly reactive reductant in anaerobic aquifers, which may also determine the fate of other classes of reducible contaminants such as halogenated solvents, azo compounds, sulfoxides, chromate, or arsenate....

Geomorphic Controls on Aquifer Geometry in Northwestern India

Science.gov (United States)

van Dijk, W. M.; Densmore, A. L.; Sinha, R.; Gupta, S.; Mason, P. J.; Singh, A.; Joshi, S. K.; Nayak, N.; Kumar, M.; Shekhar, S.

2014-12-01

The Indo-Gangetic foreland basin suffers from one of the highest rates of groundwater extraction in the world, especially in the Indian states of Punjab, Haryana and Rajasthan. To understand the effects of this extraction on ground water levels, we must first understand the geometry and sedimentary architecture of the aquifer system, which in turn depend upon its geomorphic setting. We use satellite images and digital elevation models to map the geomorphology of the Sutlej and Yamuna river systems, while aquifer geometry is assessed using ~250 wells that extend to ~300 m depth in Punjab and Haryana. The Sutlej and Yamuna rivers have deposited large sedimentary fans at their outlets. Elongate downslope ridges on the fan surfaces form distributary networks that radiate from the Sutlej and Yamuna fan apices, and we interpret these ridges as paleochannel deposits associated with discrete fan lobes. Paleochannels picked out by soil moisture variations illustrate a complex late Quaternary history of channel avulsion and incision, probably associated with variations in monsoon intensity. Aquifer bodies on the Sutlej and Yamuna fans have a median thickness of 7 and 6 m, respectively, and follow a heavy-tailed distribution, probably because of stacked sand bodies. The percentage of aquifer material in individual lithologs decreases downstream, although the exponent on the thickness distribution remains the same, indicating that aquifer bodies decrease in number down fan but do not thin appreciably. Critically, the interfan area between the Sutlej and Yamuna fans has thinner aquifers and a lower proportion of aquifer material, despite its proximal location. Our data show that the Sutlej and Yamuna fan systems form the major aquifer systems in this area, and that their geomorphic setting therefore provides a first-order control on aquifer distribution and geometry. The large spatial heterogeneity of the system must be considered in any future aquifer management scheme.

Regional modelling of the confined aquifers below the Boom clay in NE-Belgium

International Nuclear Information System (INIS)

Vandersteen, K.; Gedeon, M.; Marivoet, J.; Wouters, L.

2012-01-01

Document available in extended abstract form only. In the framework of the Belgian research program on the long term management of high-level and/or long-lived radioactive waste coordinated by ONDRAF/NIRAS, the Boom Clay is considered as a reference host rock for the geological disposal of high-level radioactive waste in NE-Belgium (Campine area). The hydrogeological program at SCK.CEN supports the long-term performance assessments of the geological disposal of radioactive waste by performing a phenomenological research of the aquifer systems surrounding the studied disposal system. One of the important components of this programme is the regional hydrogeological modelling. The regional hydrogeology is studied using two main models - the steady state Neogene aquifer model (NAM) and the transient deep aquifer pumping model (DAP), developed to characterize and quantify the regional groundwater flow in, respectively, the aquifers lying above the Boom Clay in the Nete catchment area (NAM), and the aquifers lying below the Boom Clay in the Campine area (DAP). This paper describes the most recent update of the DAP model. The DAP model represents the confined part of the groundwater system located stratigraphically below the Boom Clay. This includes the parts of the Oligocene aquifer, the Bartoon aquitard system and the Ledo-Paniselian-Brusselian aquifer buried under the Boom Clay. Due to the considerable pumping from these aquifers in combination with a limited recharge, a gradual decrease in groundwater levels has been observed in more than 30-year piezometric records. In the DAP model, the shallow aquifer system overlying the Boom Clay is replaced by fixed head boundaries: this aquifer system is dominated by close-to-surface hydrological processes and the heads fluctuate seasonally without any apparent long-term trend. In the horizontal direction, the model extends to the south as far as the outcrops of the major aquitards: the Maldegem Formation confining the Ledo

Relationship between tectonic structures and hydrogeochemical compartmentalization in aquifers: Example of the “Jeffara de Medenine” system, south–east Tunisia

Directory of Open Access Journals (Sweden)

Hayet Chihi

2015-09-01

The kriged maps of major-ion concentrations and of total dissolved solids in the aquifers were then analyzed and compared with the reservoir facies distribution for each compartment, the geometric characteristics of the aquifer, and the piezometric level trends. This allowed to characterize the hydraulic behavior of the Medenine fault and to understand the underlying physical and chemical processes having led to the spatial distribution of the geochemical properties, and thus, the hydrogeochemical functioning of the aquifers.

Quantifying Modern Recharge and Depletion Rates of the Nubian Aquifer in Egypt

Science.gov (United States)

Ahmed, Mohamed; Abdelmohsen, Karem

2018-02-01

Egypt is currently seeking additional freshwater resources to support national reclamation projects based mainly on the Nubian aquifer groundwater resources. In this study, temporal (April 2002 to June 2016) Gravity Recovery and Climate Experiment (GRACE)-derived terrestrial water storage (TWSGRACE) along with other relevant datasets was used to monitor and quantify modern recharge and depletion rates of the Nubian aquifer in Egypt (NAE) and investigate the interaction of the NAE with artificial lakes. Results indicate: (1) the NAE is receiving a total recharge of 20.27 ± 1.95 km3 during 4/2002-2/2006 and 4/2008-6/2016 periods, (2) recharge events occur only under excessive precipitation conditions over the Nubian recharge domains and/or under a significant rise in Lake Nasser levels, (3) the NAE is witnessing a groundwater depletion of - 13.45 ± 0.82 km3/year during 3/2006-3/2008 period, (4) the observed groundwater depletion is largely related to exceptional drought conditions and/or normal baseflow recession, and (5) a conjunctive surface water and groundwater management plan needs to be adapted to develop sustainable water resources management in the NAE. Findings demonstrate the use of global monthly TWSGRACE solutions as a practical, informative, and cost-effective approach for monitoring aquifer systems across the globe.

A practical assessment of aquifer discharge for regional groundwater demand by characterizing leaky confined aquifer overlain on a Mesozoic granitic gneiss basement

Science.gov (United States)

Shih, David Ching-Fang

2018-04-01

Due to increasing population worldwide, there is an urgent need to manage these important but diminishing groundwater resources efficiently to ensure their continued availability. The major innovative design of this study is to provide a practical assessment process for groundwater discharge under a regional demand by characterizing the nature of leaky confined aquifers overlain on a Mesozoic granitic gneiss basement which involves the important groundwater system in the Kinmen region (Taiwan, ROC) and the assessment of adoptable groundwater discharge in aquifer is needed. The storage coefficient presents an order of one in a thousand and hydraulic conductivity is approximately at the order of 1-8 m/d and 0.4-0.9 m/d for aquifer and aquitard respectively. Groundwater discharge and admissible number of pumping well is suggested considering scheduled maximum groundwater volume and head decline change for eastern and western studied area respectively. The safety subjected to the conservative issue is then addressed by the use of scheduled maximum groundwater volume. It reveals that the safety can be ensured using the indicator as scheduled maximum groundwater volume with predefined scenarios. The result can be utilized practically for developing management strategy of groundwater resources due to the applicability and novel of method.

Water-quality observations of the San Antonio segment of the Edwards aquifer, Texas, with an emphasis on processes influencing nutrient and pesticide geochemistry and factors affecting aquifer vulnerability, 2010–16

Science.gov (United States)

Opsahl, Stephen P.; Musgrove, MaryLynn; Mahler, Barbara J.; Lambert, Rebecca B.

2018-06-07

As questions regarding the influence of increasing urbanization on water quality in the Edwards aquifer are raised, a better understanding of the sources, fate, and transport of compounds of concern in the aquifer—in particular, nutrients and pesticides—is needed to improve water management decision-making capabilities. The U.S. Geological Survey, in cooperation with the San Antonio Water System, performed a study from 2010 to 2016 to better understand how water quality changes under a range of hydrologic conditions and in contrasting land-cover settings (rural and urban) in the Edwards aquifer. The study design included continuous hydrologic monitoring, continuous water-quality monitoring, and discrete sample collection for a detailed characterization of water quality at a network of sites throughout the aquifer system. The sites were selected to encompass a “source-to-sink” (that is, from aquifer recharge to aquifer discharge) approach. Network sites were selected to characterize rainfall, recharging surface water, and groundwater; groundwater sites included wells in the unconfined part of the aquifer (unconfined wells) and in the confined part of the aquifer (confined wells) and a major discharging spring. Storm-related samples—including rainfall samples, stormwater-runoff (surface-water) samples, and groundwater samples—were collected to characterize the aquifer response to recharge.Elevated nitrate concentrations relative to national background values and the widespread detection of pesticides indicate that the Edwards aquifer is vulnerable to contamination and that vulnerability is affected by factors such as land cover, aquifer hydrogeology, and changes in hydrologic conditions. Greater vulnerability of groundwater in urban areas relative to rural areas was evident from results for urban groundwater sites, which generally had higher nitrate concentrations, elevated δ15N-nitrate values, a greater diversity of pesticides, and higher pesticide

The role of alluvial aquifer sediments in attenuating a dissolved arsenic plume.

Science.gov (United States)

Ziegler, Brady A; Schreiber, Madeline E; Cozzarelli, Isabelle M

2017-09-01

In a crude-oil-contaminated sandy aquifer at the Bemidji site in northern Minnesota, biodegradation of petroleum hydrocarbons has resulted in release of naturally occurring As to groundwater under Fe-reducing conditions. This study used chemical extractions of aquifer sediments collected in 1993 and 2011-2014 to evaluate the relationship between Fe and As in different redox zones (oxic, methanogenic, Fe-reducing, anoxic-suboxic transition) of the contaminated aquifer over a twenty-year period. Results show that 1) the aquifer has the capacity to naturally attenuate the plume of dissolved As, primarily through sorption; 2) Fe and As are linearly correlated in sediment across all redox zones, and a regression analysis between Fe and As reasonably predicted As concentrations in sediment from 1993 using only Fe concentrations; 3) an As-rich "iron curtain," associated with the anoxic-suboxic transition zone, migrated 30m downgradient between 1993 and 2013 as a result of the hydrocarbon plume evolution; and 4) silt lenses in the aquifer preferentially sequester dissolved As, though As is remobilized into groundwater from sediment after reducing conditions are established. Using results of this study coupled with historical data, we develop a conceptual model which summarizes the natural attenuation of As and Fe over time and space that can be applied to other sites that experience As mobilization due to an influx of bioavailable organic matter. Copyright © 2017 Elsevier B.V. All rights reserved.

The role of alluvial aquifer sediments in attenuating a dissolved arsenic plume

Science.gov (United States)

Ziegler, Brady A.; Schreiber, Madeline E.; Cozzarelli, Isabelle M.

2017-01-01

In a crude-oil-contaminated sandy aquifer at the Bemidji site in northern Minnesota, biodegradation of petroleum hydrocarbons has resulted in release of naturally occurring As to groundwater under Fe-reducing conditions. This study used chemical extractions of aquifer sediments collected in 1993 and 2011–2014 to evaluate the relationship between Fe and As in different redox zones (oxic, methanogenic, Fe-reducing, anoxic-suboxic transition) of the contaminated aquifer over a twenty-year period. Results show that 1) the aquifer has the capacity to naturally attenuate the plume of dissolved As, primarily through sorption; 2) Fe and As are linearly correlated in sediment across all redox zones, and a regression analysis between Fe and As reasonably predicted As concentrations in sediment from 1993 using only Fe concentrations; 3) an As-rich “iron curtain,” associated with the anoxic-suboxic transition zone, migrated 30 m downgradient between 1993 and 2013 as a result of the hydrocarbon plume evolution; and 4) silt lenses in the aquifer preferentially sequester dissolved As, though As is remobilized into groundwater from sediment after reducing conditions are established. Using results of this study coupled with historical data, we develop a conceptual model which summarizes the natural attenuation of As and Fe over time and space that can be applied to other sites that experience As mobilization due to an influx of bioavailable organic matter.

The origin of groundwater composition in the Pampeano Aquifer underlying the Del Azul Creek basin, Argentina.

Science.gov (United States)

Zabala, M E; Manzano, M; Vives, L

2015-06-15

The Pampean plain is the most productive region in Argentina. The Pampeano Aquifer beneath the Pampean plain is used mostly for drinking water. The study area is the sector of the Pampeano Aquifer underlying the Del Azul Creek basin, in Buenos Aires province. The main objective is to characterize the chemical and isotopic compositions of groundwater and their origin on a regional scale. The methodology used involved the identification and characterization of potential sources of solutes, the study of rain water and groundwater chemical and isotopic characteristics to deduce processes, the development of a hydrogeochemical conceptual model, and its validation by hydrogeochemical modelling with PHREEQC. Groundwater samples come mostly from a two-depth monitoring network of the "Dr. Eduardo J. Usunoff" Large Plains Hydrology Institute (IHLLA). Groundwater salinity increases from SW to NE, where groundwater is saline. In the upper basin groundwater is of the HCO3-Ca type, in the middle basin it is HCO3-Na, and in the lower basin it is ClSO4-NaCa and Cl-Na. The main processes incorporating solutes to groundwater during recharge in the upper basin are rain water evaporation, dissolution of CO2, calcite, dolomite, silica, and anorthite; cationic exchange with Na release and Ca and Mg uptake, and clay precipitation. The main processes modifying groundwater chemistry along horizontal flow at 30 m depth from the upper to the lower basin are cationic exchange, dissolution of silica and anorthite, and clay precipitation. The origin of salinity in the middle and lower basin is secular evaporation in a naturally endorheic area. In the upper and middle basins there is agricultural pollution. In the lower basin the main pollution source is human liquid and solid wastes. Vertical infiltration through the boreholes annular space during the yearly flooding stages is probably the pollution mechanism of the samples at 30 m depth. Copyright © 2015 Elsevier B.V. All rights reserved.

A New Approach for Assessing Aquifer Sustainability and the Impact of Proposed Management Actions

Science.gov (United States)

Butler, J. J., Jr.; Whittemore, D. O.; Wilson, B. B.

2015-12-01

Aquifers are under stress worldwide as a result of large imbalances between inflows and outflows. These imbalances are particularly severe in aquifers in semi-arid regions that are heavily pumped for irrigation, such as the High Plains aquifer (HPA) in the United States. The water resources community has responded by placing an increasing emphasis on more sustainable management plans. To aid in the formulation of such plans, we have developed a simple, water-balance-based approach for rapid assessment of the impact of proposed management actions and the prospects for aquifer sustainability. This theoretically sound approach is particularly well suited for assessing the short- to medium-term (years to a few decades) response to management actions in seasonably pumped aquifers. The net inflow (capture) term of the aquifer water balance can also be directly calculated from water-level and water-use data with this approach. Application to the data-rich portion of the HPA in the state of Kansas reveals that practically achievable reductions in annual pumping would have a large impact. For example, a 22% reduction in average annual water use would have stabilized areally averaged water levels across northwest Kansas from 1996 to 2013 because of larger-than-expected and near-constant net inflows. Whether this is a short-term phenomenon or a path to long-term sustainability, however, has yet to be determined. Water resources managers are often in a quandary about the most effective use of scarce funds for data collection in support of aquifer assessment and management activities. This work demonstrates that a strong emphasis should be placed on collection of reliable water-use data; greater resources devoted to direct measurement of pumping will yield deeper insights into an aquifer's future. The Kansas HPA is similar to many other regional aquifers supporting critically needed agricultural production, so this approach should prove of value far beyond the borders of Kansas.

Sea-level rise impacts on seawater intrusion in coastal aquifers: Review and integration

Science.gov (United States)

Ketabchi, Hamed; Mahmoodzadeh, Davood; Ataie-Ashtiani, Behzad; Simmons, Craig T.

2016-04-01

Sea-level rise (SLR) influences groundwater hydraulics and in particular seawater intrusion (SWI) in many coastal aquifers. The quantification of the combined and relative impacts of influential factors on SWI has not previously been considered in coastal aquifers. In the present study, a systematic review of the available literature on this topic is first provided. Then, the potential remaining challenges are scrutinized. Open questions on the effects of more realistic complexities such as gradual SLR, parameter uncertainties, and the associated influences in decision-making models are issues requiring further investigation. We assess and quantify the seawater toe location under the impacts of SLR in combination with recharge rate variations, land-surface inundation (LSI) due to SLR, aquifer bed slope variation, and changing landward boundary conditions (LWBCs). This is the first study to include all of these factors in a single analysis framework. Both analytical and numerical models are used for these sensitivity assessments. It is demonstrated that (1) LSI caused by SLR has a significant incremental impact on the seawater toe location, especially in the flatter coasts and the flux-controlled (FC) LWBCs, however this impact is less than the reported orders of magnitude differences which were estimated using only analytical solutions; (2) LWBCs significantly influence the SLR impacts under almost all conditions considered in this study; (3) The main controlling factors of seawater toe location are the magnitudes of fresh groundwater discharge to sea and recharge rate. Regional freshwater flux entering from the landward boundary and the groundwater hydraulic gradient are the major contributors of fresh groundwater discharge to sea for both FC and head-controlled (HC) systems, respectively; (4) A larger response of the aquifer and larger seawater toe location changes are demonstrable for a larger ratio of the aquifer thickness to the aquifer length particularly in

Hydrogeology and water quality of the Shell Valley Aquifer, Rolette County, North Dakota

Science.gov (United States)

Strobel, M.L.

1997-01-01

The Shell Valley aquifer is the sole source of water for the city of Belcourt and the primary source of water for most of the Turtle Mountain Indian Reservation. The Turtle Mountain Band of Chippewa Indians is concerned about the quantity and quality of water in the Shell Valley aquifer, which underlies about 56 square miles in central Rolette County and has an average saturated thickness of about 35 feet. Water levels across most of the Shell Valley aquifer fluctuate with variations in precipitation but generally are stable. Withdrawals from the north well field decreased slightly during 1976-95, but withdrawals from the south well field increased during 1983-95. Water levels in the south well field declined as withdrawals increased. The average decline during the last 8 years was about 1.75 feet per year. The water level has reached the well screen in at least one of the production wells. Most of the water in the aquifer is a bicarbonate type and has dissolved-solids concentrations ranging from 479 to 1,510 milligrams per liter. None of the samples analyzed had detectable concentrations of pesticides, but hydrocarbons were detected in both ground- and surfacewater samples. Polycyclic aromatic hydrocarbons (PAH) were the most frequently detected hydrocarbons. Benzene, toluene, ethylbenzene, and xylene (BTEX), polychlorinated biphenyls (PCB), and pentachlorophenol (PCP) also were detected.Generally, the Shell Valley aquifer is an adequate source of water for current needs, but evaluation of withdrawals in relation to a knowledge of aquifer hydrology would be important in quantifying sustainable water supplies. Water quality in the aquifer generally is good; the Turtle Mountain Band of Chippewa Indians filters the water to reduce concentrations of dissolved constituents. Hydrocarbons, although present in the aquifer, have not been quantified and may not pose a general health risk. Further analysis of the quantity and distribution of the hydrocarbons would be useful

Map Showing Geology and Hydrostratigraphy of the Edwards Aquifer Catchment Area, Northern Bexar County, South-Central Texas

Science.gov (United States)

Clark, Amy R.; Blome, Charles D.; Faith, Jason R.

2009-01-01

Rock units forming the Edwards and Trinity aquifers in northern Bexar County, Texas, are exposed within all or parts of seven 7.5-minute quadrangles: Bulverde, Camp Bullis, Castle Hills, Helotes, Jack Mountain, San Geronimo, and Van Raub. The Edwards aquifer is the most prolific ground-water source in Bexar County, whereas the Trinity aquifer supplies water for residential, commercial, and industrial uses for areas north of the San Antonio. The geologic map of northern Bexar County shows the distribution of informal hydrostratigraphic members of the Edwards Group and the underlying upper member of the Glen Rose Limestone. Exposures of the Glen Rose Limestone, which forms the Trinity aquifer alone, cover approximately 467 km2 in the county. This study also describes and names five informal hydrostratigraphic members that constitute the upper member of the Glen Rose Limestone; these include, in descending order, the Caverness, Camp Bullis, Upper evaporite, Fossiliferous, and Lower evaporite members. This study improves our understanding of the hydrogeologic connection between the two aquifers as it describes the geology that controls the infiltration of surface water and subsurface flow of ground water from the catchment area (outcropping Trinity aquifer rocks) to the Edwards water-bearing exposures.

Spatial and temporal changes in sulphate-reducing groundwater bacterial community structure in response to Managed Aquifer Recharge.

Science.gov (United States)

Reed, D A; Toze, S; Chang, B

2008-01-01

The population dynamics of bacterial able to be cultured under sulphate reducing condition was studied in conjunction with changes in aquifer geochemistry using multivariate statistics for two contrasting Managed Aquifer Recharge (MAR) techniques at two different geographical locations (Perth, Western Australia and Adelaide, South Australia). Principal component analysis (PCA) was used to investigate spatial and temporal changes in the overall chemical signature of the aquifers using an array of chemical analytes which demonstrated a migrating geochemical plume. Denaturing Gradient Gel Electrophoresis (DGGE) using DNA from sulphate-reducing bacteria cultures was used to detect spatial and temporal changes in population dynamics. Bacterial and geochemical evidence suggested that groundwater at greatest distance from the nutrient source was least affected by treated effluent recharge. The results suggested that bacterial populations that were able to be cultured in sulphate reducing media responded to the migrating chemical gradient and to the changes in aquifer geochemistry. Most noticeably, sulphate-reducing bacterial populations associated with the infiltration galleries were stable in community structure over time. Additionally, the biodiversity of these culturable bacteria was restored when aquifer geochemistry returned to ambient conditions during the recovery phase at the Adelaide Aquifer Storage and Recovery site. Copyright CSIRO 2008.

Processes Governing Alkaline Groundwater Chemistry within a Fractured Rock (Ophiolitic Mélange Aquifer Underlying a Seasonally Inhabited Headwater Area in the Aladağlar Range (Adana, Turkey

Directory of Open Access Journals (Sweden)

Cüneyt Güler

2017-01-01

Full Text Available The aim of this study was to investigate natural and anthropogenic processes governing the chemical composition of alkaline groundwater within a fractured rock (ophiolitic mélange aquifer underlying a seasonally inhabited headwater area in the Aladağlar Range (Adana, Turkey. In this aquifer, spatiotemporal patterns of groundwater flow and chemistry were investigated during dry (October 2011 and wet (May 2012 seasons utilizing 25 shallow hand-dug wells. In addition, representative samples of snow, rock, and soil were collected and analyzed to constrain the PHREEQC inverse geochemical models used for simulating water-rock interaction (WRI processes. Hydrochemistry of the aquifer shows a strong interseasonal variability where Mg–HCO3 and Mg–Ca–HCO3 water types are prevalent, reflecting the influence of ophiolitic and carbonate rocks on local groundwater chemistry. R-mode factor analysis of hydrochemical data hints at geochemical processes taking place in the groundwater system, that is, WRI involving Ca- and Si-bearing phases; WRI involving amorphous oxyhydroxides and clay minerals; WRI involving Mg-bearing phases; and atmospheric/anthropogenic inputs. Results from the PHREEQC modeling suggested that hydrogeochemical evolution is governed by weathering of primary minerals (calcite, chrysotile, forsterite, and chromite, precipitation of secondary minerals (dolomite, quartz, clinochlore, and Fe/Cr oxides, atmospheric/anthropogenic inputs (halite, and seasonal dilution from recharge.

A multi-tracer approach to assess fingerprints of nitrate in an aquifer under agriculturally used land

Science.gov (United States)

Pasten-Zapata, Ernesto; Ledesma-Ruiz, Rogelio; Ramirez, Aldo; Harter, Thomas; Mahlknecht, Jürgen

2014-05-01

To effectively manage groundwater quality it is essential to understand sources of contamination and underground processes. The objective of the study was to identify sources and fate of nitrate pollution occurring in an aquifer underneath a sub-humid to humid region in NE Mexico which provides 10% of national citrus production. Nitrate isotopes and halide ratios were applied to understand nitrate sources and transformations in relation to land use/land cover. It was found that the study area is subject to diverse nitrate sources including organic waste and wastewater, synthetic fertilizers and soil processes. Animal manure and sewage from septic tanks were the causes of groundwater nitrate pollution within orchards and vegetable agriculture. Dairy activities within a radius of 1,000m from a sampling point increased nitrate pollution. Leachates from septic tanks incited nitrate pollution in residential areas. Soil nitrogen and animal waste were the sources of nitrate in groundwater under shrubland and grassland. Partial denitrification processes were evidenced. The denitrification process helped to attenuate nitrate concentration in the agricultural lands and grassland particularly during summer months.

Field trials of aquifer protection in longwall mining of shallow coal seams in China

Energy Technology Data Exchange (ETDEWEB)

Zhang, D.S.; Fan, G.W.; Liu, Y.D.; Ma, L.Q. [State Key Laboratory of Coal Resource & Mine Safety, Xuzhou (China)

2010-09-15

The large-scale mining of shallow coal seams has a significant impact on the overlying aquifers and surface ecological environment. To protect the aquifers and maximize the coal resource recovery, field trials were undertaken during the operation of the LW32201 in Bulianta coal mine, Shendong, China. With a severely weathered rock (SWR) layer and two key strata (KS) in the overlying strata, aquifer protection in longwall mining (APLM) relies mainly on the rapid advance. In some localized zones, special measures should be taken to achieve the APLM, including lowering mining height, backfill and slurry injection. To further understand the mechanism and applicable conditions of the APLM and validate the effectiveness of the APLM, variation of the water table in the aquifer was observed as the longwall face passed through the zone. This paper also discusses the mechanism and basic requirements of the APLM and the relationship between the fall of the water table and the surface subsidence. The results of the field trials indicated that APLM in shallow coal seams could be successful under suitable conditions.

Aquifer Testing And Rebound Study In Support Of The 100-H Deep Chromium Investigation

International Nuclear Information System (INIS)

Smoot, J.L.

2010-01-01

The 100-HR-3 Groundwater Operable Unit (OU) second Comprehensive Environmental Response, Compensation, and Liability Act of 1980 (CERCLA) 5-year review (DOEIRL-2006-20, The Second CERCLA Five-Year Review Report for the Hanford Site) set a milestone to conduct an investigation of deep hexavalent chromium contamination in the sediments of the Ringold upper mud (RUM) unit, which underlies the unconfined aquifer in the 100-H Area. The 5-year review noted that groundwater samples from one deep well extending below the aquitard (i.e., RUM) exceeded both the groundwater standard of 48 parts per billion (ppb) (Ecology Publication 94-06, Model Toxics Control Act Cleanup Statute and Regulation) and the federal drinking water standard of 100 μg/L for hexavalent chromium. The extent of hexavalent chromium contamination in this zone is not well understood. Action 12-1 from the 5-year review is to perform additional characterization of the aquifer below the initial aquitard. Field characterization and aquifer testing were performed in the Hanford Site's 100-H Area to address this milestone. The aquifer tests were conducted to gather data to answer several fundamental questions regarding the presence of the hexavalent chromium in the deep sediments of the RUM and to determine the extent and magnitude of deeper contamination. The pumping tests were performed in accordance with the Description of Work for Aquifer Testing in Support of the 100-H Deep Chromium Investigation (SGW-41302). The specific objectives for the series of tests were as follows: (1) Evaluate the sustainable production of the subject wells using step-drawdown and constant-rate pumping tests. (2) Collect water-level data to evaluate the degree of hydraulic connection between the RUM and the unconfined (upper) aquifer (natural or induced along the well casing). (3) Evaluate the hydraulic properties of a confined permeable layer within the RUM.; (4) Collect time-series groundwater samples during testing to evaluate

Microbiological risks of recycling urban stormwater via aquifers.

Science.gov (United States)

Page, D; Gonzalez, D; Dillon, P

2012-01-01

With the release of the Australian Guidelines for Water Recycling: Managed Aquifer Recharge (MAR), aquifers are now being included as a treatment barrier when assessing risk of recycled water systems. A MAR research site recharging urban stormwater in a confined aquifer was used in conjunction with a Quantitative Microbial Risk Assessment to assess the microbial pathogen risk in the recovered water for different end uses. The assessment involved undertaking a detailed assessment of the treatment steps and exposure controls, including the aquifer, to achieve the microbial health-based targets.

Numerical studies of CO2 and brine leakage into a shallow aquifer through an open wellbore

Science.gov (United States)

Wang, Jingrui; Hu, Litang; Pan, Lehua; Zhang, Keni

2018-03-01

Industrial-scale geological storage of CO2 in saline aquifers may cause CO2 and brine leakage from abandoned wells into shallow fresh aquifers. This leakage problem involves the flow dynamics in both the wellbore and the storage reservoir. T2Well/ECO2N, a coupled wellbore-reservoir flow simulator, was used to analyze CO2 and brine leakage under different conditions with a hypothetical simulation model in water-CO2-brine systems. Parametric studies on CO2 and brine leakage, including the salinity, excess pore pressure (EPP) and initially dissolved CO2 mass fraction, are conducted to understand the mechanism of CO2 migration. The results show that brine leakage rates increase proportionally with EPP and inversely with the salinity when EPP varies from 0.5 to 1.5 MPa; however, there is no CO2 leakage into the shallow freshwater aquifer if EPP is less than 0.5 MPa. The dissolved CO2 mass fraction shows an important influence on the CO2 plume, as part of the dissolved CO2 becomes a free phase. Scenario simulation shows that the gas lifting effect will significantly increase the brine leakage rate into the shallow freshwater aquifer under the scenario of 3.89% dissolved CO2 mass fraction. The equivalent porous media (EPM) approach used to model the wellbore flow has been evaluated and results show that the EPM approach could either under- or over-estimate brine leakage rates under most scenarios. The discrepancies become more significant if a free CO2 phase evolves. Therefore, a model that can correctly describe the complex flow dynamics in the wellbore is necessary for investigating the leakage problems.

Risk assessment and management of an oil contaminated aquifer

International Nuclear Information System (INIS)

Braxein, A.; Daniels, H.; Rouve, G.; Rubin, H.

1991-01-01

This paper concerns the provision of the basic information needed for the decision making process regarding the remedial measures leading to reutilization of an oil contaminated aquifer. The study refers to the case history of jet fuel contamination of an aquifer comprising part of the coastal aquifer of Israel. Due to that contamination two major water supply wells were abandoned. This study examines the use of numerical simulations in order to restore the contamination history of the aquifer. Such simulations also provide quantitative information needed for the decision making process regarding the future management of the contaminated aquifer

Ground-water quality assessment of the central Oklahoma Aquifer, Oklahoma; project description

Science.gov (United States)

Christenson, S.C.; Parkhurst, D.L.

1987-01-01

In April 1986, the U.S. Geological Survey began a pilot program to assess the quality of the Nation's surface-water and ground-water resources. The program, known as the National Water-Quality Assessment (NAWQA) program, is designed to acquire and interpret information about a variety of water-quality issues. The Central Oklahoma aquifer project is one of three ground-water pilot projects that have been started. The NAWQA program also incudes four surface-water pilot projects. The Central Oklahoma aquifer project, as part of the pilot NAWQA program, will develop and test methods for performing assessments of ground-water quality. The objectives of the Central Oklahoma aquifer assessment are: (1) To investigate regional ground-water quality throughout the aquifer in the manner consistent with the other pilot ground-water projects, emphasizing the occurrence and distribution of potentially toxic substances in ground water, including trace elements, organic compounds, and radioactive constituents; (2) to describe relations between ground-water quality, land use, hydrogeology, and other pertinent factors; and (3) to provide a general description of the location, nature, and possible causes of selected prevalent water-quality problems within the study unit; and (4) to describe the potential for water-quality degradation of ground-water zones within the study unit. The Central Oklahoma aquifer, which includes in descending order the Garber Sandstone and Wellington Formation, the Chase Group, the Council Grove Group, the Admire Group, and overlying alluvium and terrace deposits, underlies about 3,000 square miles of central Oklahoma and is used extensively for municipal, industrial, commercial, and domestic water supplies. The aquifer was selected for study by the NAWQA program because it is a major source for water supplies in central Oklahoma and because it has several known or suspected water-quality problems. Known problems include concentrations of arsenic, chromium

Groundwater vulnerability mapping of Qatar aquifers

Science.gov (United States)

Baalousha, Husam Musa

2016-12-01

Qatar is one of the most arid countries in the world with limited water resources. With little rainfall and no surface water, groundwater is the only natural source of fresh water in the country. Whilst the country relies mainly on desalination of seawater to secure water supply, groundwater has extensively been used for irrigation over the last three decades, which caused adverse environmental impact. Vulnerability assessment is a widely used tool for groundwater protection and land-use management. Aquifers in Qatar are carbonate with lots of fractures, depressions and cavities. Karst aquifers are generally more vulnerable to contamination than other aquifers as any anthropogenic-sourced contaminant, especially above a highly fractured zone, can infiltrate quickly into the aquifer and spread over a wide area. The vulnerability assessment method presented in this study is based on two approaches: DRASTIC and EPIK, within the framework of Geographical Information System (GIS). Results of this study show that DRASTIC vulnerability method suits Qatar hydrogeological settings more than EPIK. The produced vulnerability map using DRASTIC shows coastal and karst areas have the highest vulnerability class. The southern part of the country is located in the low vulnerability class due to occurrence of shale formation within aquifer media, which averts downward movement of contaminants.

The Guarani Aquifer System: estimation of recharge along the Uruguay-Brazil border

Science.gov (United States)

Gómez, Andrea A.; Rodríguez, Leticia B.; Vives, Luis S.

2010-11-01

The cities of Rivera and Santana do Livramento are located on the outcropping area of the sandstone Guarani Aquifer on the Brazil-Uruguay border, where the aquifer is being increasingly exploited. Therefore, recharge estimates are needed to address sustainability. First, a conceptual model of the area was developed. A multilayer, heterogeneous and anisotropic groundwater-flow model was built to validate the conceptual model and to estimate recharge. A field campaign was conducted to collect water samples and monitor water levels used for model calibration. Field data revealed that there exists vertical gradients between confining basalts and underlying sandstones, suggesting basalts could indirectly recharge sandstone in fractured areas. Simulated downward flow between them was a small amount within the global water budget. Calibrated recharge rates over basalts and over outcropping sandstones were 1.3 and 8.1% of mean annual precipitation, respectively. A big portion of sandstone recharge would be drained by streams. The application of a water balance yielded a recharge of 8.5% of average annual precipitation. The numerical model and the water balance yielded similar recharge values consistent with determinations from previous authors in the area and other regions of the aquifer, providing an upper bound for recharge in this transboundary aquifer.

Aquifers Characterization and Productivity in Ellala Catchment ...

African Journals Online (AJOL)

user

Aquifers Characterization and Productivity in Ellala Catchment, Tigray, ... using geological and hydrogeological methods in Ellala catchment (296.5km. 2. ) ... Current estimates put the available groundwater ... Aquifer characterization takes into.

Transient well flow in leaky multiple-aquifer systems

Science.gov (United States)

Hemker, C. J.

1985-10-01

A previously developed eigenvalue analysis approach to groundwater flow in leaky multiple aquifers is used to derive exact solutions for transient well flow problems in leaky and confined systems comprising any number of aquifers. Equations are presented for the drawdown distribution in systems of infinite extent, caused by wells penetrating one or more of the aquifers completely and discharging each layer at a constant rate. Since the solution obtained may be regarded as a combined analytical-numerical technique, a type of one-dimensional modelling can be applied to find approximate solutions for several complicating conditions. Numerical evaluations are presented as time-drawdown curves and include effects of storage in the aquitard, unconfined conditions, partially penetrating wells and stratified aquifers. The outcome of calculations for relatively simple systems compares very well with published corresponding results. The proposed multilayer solution can be a valuable tool in aquifer test evaluation, as it provides the analytical expression required to enable the application of existing computer methods to the determination of aquifer characteristics.

A Review on Concepts, Applications, and Models of Aquifer Thermal Energy Storage Systems

Directory of Open Access Journals (Sweden)

Kun Sang Lee

2010-06-01

Full Text Available Being a heat source or sink, aquifers have been used to store large quantities of thermal energy to match cooling and heating supply and demand on both a short-term and long-term basis. The current technical, economic, and environmental status of aquifer thermal energy storage (ATES is promising. General information on the basic operation principles, design, and construction of ATES systems is discussed in this paper. Numerous projects in operation around the world are summarized to illustrate the present status of ATES. Hydrogeological-thermal simulation has become an integral part of predicting ATES system performance. Numerical models which are available to simulate an ATES system by modeling mass and heat transport in the aquifer have been summarized. This paper also presents an example of numerical simulation and thermohydraulic evaluation of a two-well, ATES system operating under a continuous flow regime.

Site-specific variability in BTEX biodegradation under denitrifying conditions

International Nuclear Information System (INIS)

Kao, C.M.; Borden, R.C.

1997-01-01

Laboratory microcosm experiments were conducted to evaluate the feasibility of benzene, toluene, ethylbenzene, m-xylene, and o-xylene (BTEX) biodegradation under denitrifying conditions. Nine different sources of inocula, including contaminated and uncontaminated soil cores from four different sites and activated sludge, were used to establish microcosms. BTEX was not degraded under denitrifying conditions in microcosms inoculated with aquifer material from Rocky Point and Traverse City. However, rapid depletion of glucose under denitrifying conditions was observed in microcosms containing Rocky Point aquifer material. TEX degradation was observed in microcosms containing Rocky Point aquifer material. TEX degradation was observed in microcosms containing aquifer material from Fort Bragg and Sleeping Bear Dunes and sewage sludge. Benzene was recalcitrant in all microcosms tested. The degradation of o-xylene ceased after toluene, ethylbenzene, and m-xylene were depleted in the Fort Bragg and sludge microcosms, but o-xylene continued to degrade in microcosms with contaminated Sleeping Bear Dunes soil. The most probable number (MPN) of denitrifiers in these nine different inocula were measured using a microtiter technique. There was no correlation between the MPN of denitrifiers and the TEX degradation rate under denitrifying conditions. Experimental results indicate that the degradation sequence and TEX degradation rate under denitrifying conditions may differ among sites. Results also indicate that denitrification alone may not be a suitable bioremediation technology for gasoline-contaminated aquifers because of the inability of denitrifiers to degrade benzene

Managed Aquifer Recharge: from Local Research and Experiences to Regional Aquifer Storage and Recovery

Science.gov (United States)

Hendriks, D.; Faneca, M.; Oude Essink, G.; van Baaren, E.; Stuurman, R.; Delsman, J. R.; van Kempen, C.; de Louw, P.

2016-12-01

Many areas in the world experience periodic water shortages due to meteorological drought, salt water intrusion or over-exploitation of the water resources. Recently, it was established that the depletion of aquifers in many areas of the world is in an advanced state (Gleeson et al, 2012). This poses enormous challenges as 2.5 billion people and many companies depend on groundwater now and in the future (UN, 2015; ESG, 2016). A solution to increase robustness of water systems and prevent water shortage is subsurface storage of water during wet periods using Managed Aquifer Research (MAR). In addition to mitigation of water shortage, MAR can also reduce the occurrence and degree of flooding. Here, we present an overview of Deltares MAR expertise and available tools for up-scaling MAR. Deltares has experience with both research and implementation of MAR in different parts of the world under various hydro(geo)logical, climatic and socio-economic conditions. Various MAR techniques were assessed/tested in coastal areas of the Netherlands, Spain, New York, New Orleans and in Bangladesh. In some of these areas specific groundwater shortage related issues occur, such as salt water intrusion or subsidence. In Singapore, monitoring campaigns and modeling were done to design MAR by infiltration of water in over-exploited aquifers. In Abu Dhabi, geophysical methods were used to detect the optimal conditions for MAR systems. To effectively increase the robustness of groundwater systems up-scaling of MAR is required. For this purpose, Deltares developed tools that provide insight in the potential demand, possibilities and effectiveness of MAR at larger scales. The Quick scan tool for Fresh Groundwater Buffering provides insight on regional to national scale and is based on GIS-information of water demand, water resources, and subsurface properties. This quick scan tool has been applied for Mozambique, Kenya, India and Bangladesh. The Fresh Water Optimizer assesses the

Fate of seven pesticides in an aerobic aquifer studied in column experiments

DEFF Research Database (Denmark)

Tuxen, Nina; Tuchsen, Peter Lysholm; Rügge, K.

2000-01-01

The fate of selected pesticides (bentazone, isoproturon, DNOC, MCPP, dichlorprop and 2,4-D) and a metabolite (2,6-dichlorobenzamide (BAM)) was investigated under aerobic conditions in column experiments using aquifer material and low concentrations of pesticides (approximately 25 lg/l). A solute...

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

Science.gov (United States)

Melo, D. D.; Wendland, E.

2013-12-01

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

Factors Affecting Public-Supply Well Vulnerability in Two Karst Aquifers

OpenAIRE

Musgrove, MaryLynn; Katz, Brian G; Fahlquist, Lynne S; Crandall, Christy A; Lindgren, Richard J

2014-01-01

Karst aquifers occur in a range of climatic and geologic settings. Nonetheless, they are commonly characterized by their vulnerability to water-quality impairment. Two karst aquifers, the Edwards aquifer in south-central Texas and the Upper Floridan aquifer in western Florida, were investigated to assess factors that control the movement of contaminants to public-supply wells (PSWs). The geochemistry of samples from a selected PSW or wellfield in each aquifer was compared with that from nearb...

Remediation of a contaminated thin aquifer by horizontal wells

Energy Technology Data Exchange (ETDEWEB)

Breh, W.; Suttheimer, J.; Hoetzl, H. [Univ. of Karlsruhe (Germany); Frank, K. [GEO-Service GmbH, Rheinmuenster (Germany)

1997-12-31

At an industrial site in Bruchsal (Germany) a huge trichloroethene contamination was found. After common remedial actions proved to be widely ineffective, new investigations led to a highly contaminated thin aquifer above the main aquifer. The investigation and the beginning of the remediation of the thin aquifer by two horizontal wells is described in this paper. Special attention was given to the dependence between precipitation and the flow direction in the thin aquifer and to hydraulic connections between the thin and the main aquifer. Also a short introduction into a new remedial technique by horizontal wells and first results of the test phase of the horizontal wells are given.

Consequences and mitigation of saltwater intrusion induced by short-circuiting during aquifer storage and recovery in a coastal subsurface

Science.gov (United States)

Gerardus Zuurbier, Koen; Stuyfzand, Pieter Jan

2017-02-01

Coastal aquifers and the deeper subsurface are increasingly exploited. The accompanying perforation of the subsurface for those purposes has increased the risk of short-circuiting of originally separated aquifers. This study shows how this short-circuiting negatively impacts the freshwater recovery efficiency (RE) during aquifer storage and recovery (ASR) in coastal aquifers. ASR was applied in a shallow saltwater aquifer overlying a deeper, confined saltwater aquifer, which was targeted for seasonal aquifer thermal energy storage (ATES). Although both aquifers were considered properly separated (i.e., a continuous clay layer prevented rapid groundwater flow between both aquifers), intrusion of deeper saltwater into the shallower aquifer quickly terminated the freshwater recovery. The presumable pathway was a nearby ATES borehole. This finding was supported by field measurements, hydrochemical analyses, and variable-density solute transport modeling (SEAWAT version 4; Langevin et al., 2007). The potentially rapid short-circuiting during storage and recovery can reduce the RE of ASR to null. When limited mixing with ambient groundwater is allowed, a linear RE decrease by short-circuiting with increasing distance from the ASR well within the radius of the injected ASR bubble was observed. Interception of deep short-circuiting water can mitigate the observed RE decrease, although complete compensation of the RE decrease will generally be unattainable. Brackish water upconing from the underlying aquitard towards the shallow recovery wells of the ASR system with multiple partially penetrating wells (MPPW-ASR) was observed. This leakage may lead to a lower recovery efficiency than based on current ASR performance estimations.

Modelling studies for influence factors of gas bubble in compressed air energy storage in aquifers

International Nuclear Information System (INIS)

Guo, Chaobin; Zhang, Keni; Li, Cai; Wang, Xiaoyu

2016-01-01

CAES (Compressed air energy storage) is credited with its potential ability for large-scale energy storage. Generally, it is more convenient using deep aquifers than employing underground caverns for energy storage, because of extensive presence of aquifers. During the first stage in a typical process of CAESA (compressed air energy storage in aquifers), a large amount of compressed air is injected into the target aquifer to develop an initial space (a gas bubble) for energy storage. In this study, numerical simulations were conducted to investigate the influence of aquifer's permeability, geological structure and operation parameters on the formation of gas bubble and the sustainability for the later cycling operation. The SCT (system cycle times) was designed as a parameter to evaluate the reservoir performance and the effect of operation parameters. Simulation results for pressure and gas saturation results of basic model confirm the feasibility of compressed air energy storage in aquifers. The results of different permeability cases show that, for a certain scale of CAESA system, there is an optimum permeability range for a candidate aquifer. An aquifer within this permeability range will not only satisfy the injectivity requirement but also have the best energy efficiency. Structural impact analysis indicates that the anticline structure has the best performance to hold the bubble under the same daily cycling schedule with the same initial injected air mass. In addition, our results indicate that the SCT shows a logarithmic growth as the injected air mass increase. During the formation of gas bubble, compressed air should be injected into aquifers with moderate rate and the injection can be done in several stages with different injection rate to avoid onset pressure. - Highlights: • Impact of permeability, geological structure, operation parameters was investigated. • With certain air production rate, an optimum permeability exists for performance. �

40 CFR 147.502 - Aquifer exemptions. [Reserved

Science.gov (United States)

2010-07-01

... 40 Protection of Environment 22 2010-07-01 2010-07-01 false Aquifer exemptions. [Reserved] 147.502... (CONTINUED) STATE, TRIBAL, AND EPA-ADMINISTERED UNDERGROUND INJECTION CONTROL PROGRAMS Florida § 147.502 Aquifer exemptions. [Reserved] ...

Uranium series geochemistry in aquifers: quantification of transport mechanisms of uranium and daughter products: the chalk aquifer (Champagne, France)

International Nuclear Information System (INIS)

Hubert, A.

2005-09-01

With the increase of contaminant flux of radionuclides in surface environment (soil, river, aquifer...), there is a need to understand and model the processes that control the distribution of uranium and its daughter products during transport within aquifers. We have used U-series disequilibria as an analogue for the transport of uranium and its daughter products in aquifer to understand such mechanisms. The measurements of uranium ( 234 U et 238 U), thorium ( 230 Th et 232 Th), 226 Ra and 222 Rn isotopes in the solid and liquid phases of the chalk aquifer in Champagne (East of France) allows us to understand the processes responsible for fractionation within the uranium decay chain. Fractionations are induced by physical and chemical properties of the elements (leaching, adsorption) but also by radioactive properties (recoil effect during α-decay). For the first time a comprehensive sampling of the solid phase has been performed, allowing quantifying mechanisms responsible for the long term evolution of the aquifer. A non steady state 1D model has been developed which takes into account leaching, adsorption processes as well as radioactive filiation and α-recoil effect. Retardation coefficients have been calculated for uranium, thorium and radium. The aquifer is characterised by a double porosity, and the contribution of fracture and matrix porosity on the water/rock interaction processes has been estimated. (author)

Hydrologic connections and dynamics of water movement in the classical Karst (Kras) Aquifer: evidence from frequent chemical and stable isotope sampling

Science.gov (United States)

Doctor, Daniel H.

2008-01-01

A review of past research on the hydrogeology of the Classical Karst (Kras) region and new information obtained from a two- year study using environmental tracers are presented in this paper. The main problems addressed are 1) the sources of water to the Kras aquifer resurgence zone-including the famous Timavo springs-under changing flow regimes; 2) a quantification of the storage volumes of the karst massif corresponding to flow regimes defined by hydrograph recessions of the Timavo springs; and 3) changing dynamics between deep phreatic conduit flow and shallow phreatic and epiphreatic storage within the aquifer resurgence zone as determined through changes in chemical and isotopic composition at springs and wells. Particular focus was placed on addressing the long-standing question of the influence of the Soca River on the ground waters of the aquifer resurgence zone. The results indicate that the alluvial aquifer supplied by the sinking of the Soca River on the northwestern edge of the massif contributes approximately 75% of the mean annual outflow to the smaller springs of the aquifer resurgence zone, and as much as 53% to the mean annual outflow of the Timavo springs. As a whole, the Soca River is estimated to contribute 56% of the average outflow of the Kras aquifer resurgence. The proportions of Soca River water increase under drier conditions, and decrease under wetter conditions. Time series analysis of oxygen stable isotope records indicate that the transit time of Soca River water to the Timavo springs, Sardos spring, and well B-4 is on the order of 1-2 months, depending on hydrological conditions. The total baseflow storage of the Timavo springs is estimated to be 518 million m3, and represents 88.5% of the storage capacity estimated for all flow regimes of the springs. The ratio of baseflow storage volume to the average annual volume discharged at the Timavo springs is 0.54. The Reka River sinking in Slovenia supplies substantial allogenic recharge to

Seismic velocities to characterize the soil-aquifer continuum on the Orgeval experimental basin (France)

Science.gov (United States)

Pasquet, S.; Ludovic, B.; Dhemaied, A.; Flipo, N.; Guérin, R.; Mouhri, A.; Faycal, R.; Vitale, Q.

2013-12-01

Among geophysical methods applied to hydrogeology, seismic prospecting is frequently confined to the characterization of aquifers geometry. The combined study of pressure- (P) and shear- (SH) wave velocities (respectively Vp and Vs) can however provide information about the aquifer parameters, as it is commonly done for most fluids in hydrocarbon exploration. This approach has recently been proposed in sandy aquifers with the estimation of Vp/Vs ratio. In order to address such issues in more complex aquifer systems (e.g. unconsolidated, heterogeneous or low-permeability media) we carried out P- and SH-wave seismic surveys on the Orgeval experimental basin (70 km east from Paris, France). This basin drains a multi-layer aquifer system monitored by a network of piezometers. The upper part of the aquifer system is characterized by tabular layers well delineated all over the basin thanks to Electrical Resistivity Tomography (ERT), Time Domain ElectroMagnetic (TDEM) soundings and wells. But the lateral variability of the intrinsic properties in each layer raises questions regarding the hydrodynamics of the upper aquifer and the validity of interpolations between piezometers. A simple interpretation of P- and SH-wave first arrivals for tabular models provides 1D velocity structures in very good agreement with the stratification anticipated from ERT and nearby geological logs. Vp/Vs ratios show a strong contrast at a depth consistent with the observed water table level, reinforcing the assumption of a free upper aquifer in the area. Similar experiments have to be conducted under different hydrological conditions to validate these observations. Anticipating the need to propose lateral applications of the method, we additionally performed tomographic inversions of the recorded data to retrieve 2D Vp and Vs models. If interpreted independently, both models fail to depict the stratification of the medium and the water table level cannot be straightforwardly identified

Assessment of hydraulic properties of sedimentary and volcanic aquifer systems under arid conditions in the Republic of Djibouti (Horn of Africa)

Science.gov (United States)

Jalludin, Mohamed; Razack, Moumtaz

The Republic of Djibouti (23,000 km2 500,000 inhabitants), located within the Horn of Africa, undergoes an arid climate with an average annual rainfall less than 150 mm. Water resources are provided up to 98% by groundwater. Two types of aquifers are encountered: volcanic and sedimentary aquifers. This paper focuses on the assessment of their hydraulic properties, which is necessary for future tasks regarding the management of these aquifers. To this end, a data base consisting of all available pumping test data obtained since the 1960s was compiled. Pumping tests have been interpreted to determine transmissivity. Solely for volcanic aquifers, transmissivity also has been estimated through an empirical relationship using specific capacity corrected for turbulent well losses. The transmissivity of each type of aquifer can span up to four orders of magnitude, pointing out their strong heterogeneity. For the various volcanic rocks, the younger the rock, the higher the transmissivity. The transmissivity of volcanic rocks has therefore decreased in the course of geological time. At present, a much better understanding of the hydraulic properties of these complex aquifers has been obtained, which should enable optimal management of their groundwater resources through the use of numerical modeling. La République de Djibouti (23,000 km2 500,000 habitants), située dans la Corne de l'Afrique, subit un climat aride avec une pluviométrie moyenne annuelle inférieure à 150 mm. Les ressources en eau sont fournies à plus de 98% par les eaux souterraines contenues dans des aquifères sédimentaires ou volcaniques. Cet article a pour objectif l'évaluation des propriétés hydrauliques de ces aquifères, étape indispensable pour entreprendre par la suite des études en vue de la gestion de ces aquifères. Une base rassemblant les données d'essais par pompage disponibles depuis les années Soixante a d'abord été établie. Les essais par pompage ont été interprétés pour

Soil Aquifer Treatment : Assessment and Applicability of Primary Effluent Reuse in Developing Countries

NARCIS (Netherlands)

Abel, C.D.T.

2014-01-01

This thesis showed that soil aquifer treatment (SAT) is an effective polishing technology for reuse of primary effluent. The study experimentally revealed relatively high removal of suspended solids, bulk organic matter, nutrients, pharmaceutically active compounds and pathogens indicators under

Soil Aquifer Treatment: Assessment and Applicability of Primary Effluent Reuse in Developing Countries

NARCIS (Netherlands)

Abel, C.D.T.

2014-01-01

This thesis showed that soil aquifer treatment (SAT) is an effective polishing technology for reuse of primary effluent. The study experimentally revealed relatively high removal of suspended solids, bulk organic matter, nutrients, pharmaceutically active compounds and pathogens indicators under

Bioremediation of a diesel fuel contaminated aquifer: simulation studies in laboratory aquifer columns

Science.gov (United States)

Hess, A.; Höhener, P.; Hunkeler, D.; Zeyer, J.

1996-08-01

The in situ bioremediation of aquifers contaminated with petroleum hydrocarbons is commonly based on the infiltration of groundwater supplemented with oxidants (e.g., O 2, NO 3-) and nutrients (e.g., NH 4+, PO 43-). These additions stimulate the microbial activity in the aquifer and several field studies describing the resulting processes have been published. However, due to the heterogeneity of the subsurface and due to the limited number of observation wells usually available, these field data do not offer a sufficient spatial and temporal resolution. In this study, flow-through columns of 47-cm length equipped with 17 sampling ports were filled with homogeneously contaminated aquifer material from a diesel fuel contaminated in situ bioremediation site. The columns were operated over 96 days at 12°C with artificial groundwater supplemented with O 2, NO 3- and PO 43-. Concentration profiles of O 2, NO 3-, NO 2-, dissolved inorganic and organic carbon (DIC and DOC, respectively), protein, microbial cells and total residual hydrocarbons were measured. Within the first 12 cm, corresponding to a mean groundwater residence time of < 3.6 h, a steep O 2 decrease from 4.6 to < 0.3 mg l -1, denitrification, a production of DIC and DOC, high microbial cell numbers and a high removal of hydrocarbons were observed. Within a distance of 24 to 40.5 cm from the infiltration, O 2 was below 0.1 mg l -1 and a denitrifying activity was found. In the presence and in the absence of O 2, n-alkanes were preferentially degraded compared to branched alkanes. The results demonstrate that: (1) infiltration of aerobic groundwater into columns filled with aquifer material contaminated with hydrocarbons leads to a rapid depletion of O 2; (2) O 2 and NO 3- can serve as oxidants for the mineralization of hydrocarbons; and (3) the modelling of redox processes in aquifers has to consider denitrifying activity in presence of O 2.

Aquifer recharging in South Carolina: radiocarbon in environmental hydrogeology

International Nuclear Information System (INIS)

Stone, P.A.; Knox, R.L.; Mathews, T.D.

1985-01-01

Radiocarbon activities of dissolved inorganic carbon (and tritium activities where infiltration rates are rapid and aquifers shallow) provide relatively unambiguous and inexpensive evidence for identification of significant recharge areas. Such evidence is for the actual occurrence of modern recharge in the aquifer and thus is less inferential than stratigraphic or potentiometric evidence. These underutilized isotopic techniques are neither arcane nor complex and have been more-or-less standardized by earlier researchers. In South Carolina, isotopic evidence has been used from both calcareous and siliceous sedimentary aquifers and fractured crystalline rock aquifers. The Tertiary limestone aquifer is shown not to be principally recharged in its subcrop area, unlike conditions assumed for many other sedimentary aquifers in southeastern United States, and instead receives considerable lateral recharge from interfingering updip Tertiary sand aquifers in the middle coastal plain. Induced recharging at Hilton Head Island is mixing ancient relict water and modern recharge water. Recharging to deeper portions of the Cretaceous Middendorf basal sand aquifer occurs at least as far coastward as the middle coastal plain, near sampling sites that stratigraphically appear to be confined. Pronounced mineralization of water in fractured rocks cannot be considered as evidence of ancient or relict ground water that is isolated from modern contaminants, some of these waters contain considerable radiocarbon and hydrogen-bomb tritium

Conjunctive use Management under Uncertainty in Aquifer Parameters

Directory of Open Access Journals (Sweden)

Mahmoud Mohammad Rezapour Tabari

2010-01-01

Full Text Available Conjunctive use operation policies play a vital role in the sustainability of water resources and their optimal allocation. To be realistic conditions of real water resource system should be considered in simulation and derivation of operating rules of real-world water resource system. In this research, the combined fuzzy logic and direct search optimization technique is used to account for the uncertainty associated with parameters affecting groundwater table level fluctuations. These parameters include specific yields and inflow recharge and outflow discharge from the aquifer, which are typically uncertain. A membership function is determined for each parameter using hydrogeologic and piezometric data. For each membership value ( level cut, the corresponding intervals are determined. These intervals are considered as constraints on the membership value of the groundwater table level fluctuations in the optimization model. The process is repeated for other  level cuts to obtain the fuzzy number. For the uncertainty influencing the water demands, a conjunctive use model with water resources constraints is developed. Using this model, the priorities for the different zones and their optimal allocations are determined. The results show that the better the real conditions are reflected in the conjunctive use model, the better will the system be reliably capable of handling the water demands. The results of the proposed model also indicate that it present reliable allocations compared to the static conventional models and that it performs more desirably and practically in allocating supplies to water demands as it duly includes the opinions of the decision-makers involved.

Conceptual understanding and groundwater quality of selected basin-fill aquifers in the Southwestern United States

Science.gov (United States)

Thiros, Susan A.; Bexfield, Laura M.; Anning, David W.; Huntington, Jena M.

2010-01-01

the arid to semiarid climate, cultural and economic activities in the Southwest are particularly dependent on supplies of good-quality groundwater. Irrigation and public-supply withdrawals from basin-fill aquifers in the study area account for about one quarter of the total withdrawals from all aquifers in the United States.Many factors influence the quality of groundwater in the 15 case-study basins, but some common factors emerge from the basin summaries presented in this report. These factors include the chemical composition of the recharge water, consolidated rock geology and composition of aquifer materials derived from consolidated rock, and land and water use. The major water-quality issues in many of the developed case-study basins are increased concentrations of dissolved solids, nitrate, and VOCs in groundwater as a result of human activities.The information presented and the citations listed in this report serve as a resource for those interested in the groundwater-flow systems in the NAWQA case-study basins. The summaries of water-development history, hydrogeology, conceptual understanding of the groundwater system under both predevelopment and modern conditions, and effects of natural and human-related factors on groundwater quality presented in the sections on each basin also serve as a foundation for the synthesis and modeling phases of the SWPA regional study.

Groundwater salinity in coastal aquifer of Karachi, Pakistan

International Nuclear Information System (INIS)

Mashiatullah, A.; Qureshi, R.M.; Ahmad, E.; Tasneem, M.A.; Sajjad, M.I.; Khan, H.A.

2002-01-01

Potable groundwater salinity has become a problem of great concern in the Karachi Metropolis, which is not only the most populous and biggest industrial base but also the largest coastal dwelling of Pakistan. Stable isotope techniques [O/sup 18/ content of Oxygen in the water molecular and C/sup 13/ content of the Total Dissolved Inorganic Carbon (TDIC)] have been used, in conjunction with physiochemical tools (temperature, dissolved oxygen, pH, redox electrical conductivity, salinity), to examine the quality of potable water and the source of salinity. Surface water samples (12 No.) were collected from polluted streams, namely: Layeri River, Malir River; Hub River/Hub Lake and the Indus River. Shallow groundwater samples (7 No. ) were collected from operating dug wells. Relatively deep groundwater samples (12 No.) were collected from operating dug wells, relatively deep groundwater samples (12 No.) were collected from pumping wells/tube-wells. Physicochemical analysis of water samples was completed in the field. In the laboratory, water samples were analyzed for O/sup 18/ content of oxygen in the water molecule and C/sup 13/ content of the TDIC, using specific gas extraction systems and a modified GD-150 gas source mass spectrometer. It is concluded from this preliminary investigation that the potable aquifer system in coastal Karachi hosts a mixture of precipitation (rainwater only) from hinterlands, trapped seawater in relatively deep aquifer system, as well as intruded seawater under natural infiltration conditions and/or induced recharge conditions (in shallow aquifers). (author)

Carbon Sequestration in Saline Aquifers: Modeling Diffusive and Convective Transport Of a Carbon-­Dioxide Cap

KAUST Repository

Allen, Rebecca

2011-01-01

done on the diffusive-convective transport that occurs under a cap of CO2-saturated fluid, which results after CO2 is injected into an aquifer and spreads laterally under an area of low permeability. The diffusive-convective modeling reveals an enhanced

Accounting for the Decreasing Reaction Potential of Heterogeneous Aquifers in a Stochastic Framework of Aquifer-Scale Reactive Transport

Science.gov (United States)

Loschko, Matthias; Wöhling, Thomas; Rudolph, David L.; Cirpka, Olaf A.

2018-01-01

Many groundwater contaminants react with components of the aquifer matrix, causing a depletion of the aquifer's reactivity with time. We discuss conceptual simplifications of reactive transport that allow the implementation of a decreasing reaction potential in reactive-transport simulations in chemically and hydraulically heterogeneous aquifers without relying on a fully explicit description. We replace spatial coordinates by travel-times and use the concept of relative reactivity, which represents the reaction-partner supply from the matrix relative to a reference. Microorganisms facilitating the reactions are not explicitly modeled. Solute mixing is neglected. Streamlines, obtained by particle tracking, are discretized in travel-time increments with variable content of reaction partners in the matrix. As exemplary reactive system, we consider aerobic respiration and denitrification with simplified reaction equations: Dissolved oxygen undergoes conditional zero-order decay, nitrate follows first-order decay, which is inhibited in the presence of dissolved oxygen. Both reactions deplete the bioavailable organic carbon of the matrix, which in turn determines the relative reactivity. These simplifications reduce the computational effort, facilitating stochastic simulations of reactive transport on the aquifer scale. In a one-dimensional test case with a more detailed description of the reactions, we derive a potential relationship between the bioavailable organic-carbon content and the relative reactivity. In a three-dimensional steady-state test case, we use the simplified model to calculate the decreasing denitrification potential of an artificial aquifer over 200 years in an ensemble of 200 members. We demonstrate that the uncertainty in predicting the nitrate breakthrough in a heterogeneous aquifer decreases with increasing scale of observation.

Evidence for Upward Flow of Saline Water from Depth into the Mississippi River Valley Alluvial Aquifer in Southeastern Arkansas

Science.gov (United States)

Larsen, D.; Paul, J.

2017-12-01

Groundwater salinization is occurring in the Mississippi River Valley Alluvial (MRVA) aquifer in southeastern Arkansas (SE AR). Water samples from the MRVA aquifer in Chicot and Desha counties have yielded elevated Cl-concentrations with some as high as 1,639 mg/L. Considering that the MRVA aquifer is the principle source of irrigation water for the agricultural economy of SE AR, salinization needs to be addressed to ensure the sustainability of crop, groundwater, and soil resources in the area. The origin of elevated salinity in MRVA aquifer was investigated using spatial and factor analysis of historical water quality data, and sampling and tracer analysis of groundwater from irrigation, municipal, and flowing industrial wells in SE AR. Spatial analysis of Cl- data in relation to soil type, geomorphic features and sand-blow density indicate that the Cl- anomalies are more closely related to the sand-blow density than soil data, suggesting an underlying tectonic control for the distribution of salinity. Factor analysis of historical geochemical data from the MRVA and underlying Sparta aquifer shows dilute and saline groups, with saline groups weighted positively with Cl- or Na+ and Cl-. Tracer data suggest a component of evaporatively evolved crustal water of pre-modern age has mixed with younger, fresher meteoric sources in SE AR to create the saline conditions in the MRVA aquifer. Stable hydrogen and oxygen values of waters sampled from the Tertiary Sparta and MRVA aquifers deviate from the global and local meteoric water lines along an evaporative trend (slope=4.4) and mixing line with Eocene Wilcox Group groundwaters. Ca2+ and Cl- contents vary with Br- along mixing trends between dilute MRVA water and Jurassic Smackover Formation pore fluids in southern AR. Increasing Cl- content with C-14 age in MRVA aquifer groundwater suggests that the older waters are more saline. Helium isotope ratios decrease with He gas content for more saline water, consistent with

Geohydrology of the valley-fill aquifer in the Corning area, Steuben County, New York

Science.gov (United States)

Miller, Todd S.; Belli, J.L.; Allen, R.V.

1982-01-01

This report is the seventh in a series of 11 map sets depicting geohydrologic conditions in selected aquifers in upstate New York. Geohydrologic data are compiled on six maps at 1:24,000 scale. Together, the maps provide a comprehensive overview of a major valley-fill aquifer in southeastern Steuben County. The maps include surficial geology, geologic sections, water-infiltration potential of soil zone, aquifer thickness, potentiometric-surface elevations, and land use. The valley-fill deposits consist of alluvial silt, sand, and gravel, glacial-outwash (sand and gravel), till, and lacustrine silt and clay. The sand and gravel beds have relatively high permeabilities, whereas the till and silt deposits have relatively low permeabilities. Water-table conditions prevail in unconfined sand and gravel along the valley margin. Artesian conditions are found locally in sand and gravel confined under silt and clay in the middle of the valley. Recharge occurs nearly everywhere on the valley floor, but principally along the margin of the valley, where highly permeable land surface conditions exist, and runoff from the hillsides is concentrated. The use of land overlying the aquifer is a mixture of residential, commercial, agricultural, and industrial uses. (USGS)

Geohydrology of the valley-fill aquifer in the Jamestown area, Chautauqua County, New York

Science.gov (United States)

Anderson, H.R.; Stelz, W.G.; Belli, J.L.; Allen, R.V.

1982-01-01

This report is the sixth in a series of 11 map sets depicting geohydrologic conditions in selected aquifers in upstate New York. Geohydrologic data are compiled on six maps at 1:24,000 scale. Together, the maps provide a comprehensive overview of a major valley-fill aquifer in southeastern Chautauqua County. The maps include surficial geology, geologic sections, water-infiltration potential of soil zone, aquifer thickness, potentiometric-surface elevations and land use. The valley-fill deposits consist of alluvial silt and sand, glacial-outwash (sand and gravel), ice-contact sand and gravel, till, and lacustrine silt and clay. The sand and gravel beds have relatively high permeabilities whereas the till, silt and clay deposits have relatively low permeabilities. Water-table conditions prevail in u nconfined sand and gravel beds along the valley margin. Artesian conditions prevail in confined sand and gravel buried under silt and clay in the middle of the valley. Recharge occurs mainly along the margin of the valley, where the land surface is highly permeable and runoff from the hillsides is concentrated. The use of land overlying the aquifer is predominantly agricultural and residential with lesser amounts of commercial and industrial uses. (USGS)

Simulating the 2012 High Plains Drought Using Three Single Column Model Versions of the Community Earth System Model (SCM-CESM)

Science.gov (United States)

Medina, I. D.; Denning, S.

2014-12-01

The impact of changes in the frequency and severity of drought on fresh water sustainability is a great concern for many regions of the world. One such location is the High Plains, where the local economy is primarily driven by fresh water withdrawals from the Ogallala Aquifer, which accounts for approximately 30% of total irrigation withdrawals from all U.S. aquifers combined. Modeling studies that focus on the feedback mechanisms that control the climate and eco-hydrology during times of drought are limited in the sense that they use conventional General Circulation Models (GCMs) with grid length scales ranging from one hundred to several hundred kilometers. Additionally, these models utilize crude statistical parameterizations of cloud processes for estimating sub-grid fluxes of heat and moisture and have a poor representation of land surface heterogeneity. For this research, we focus on the 2012 High Plains drought, and will perform numerical simulations using three single column model versions of the Community Earth System Model (SCM-CESM) at multiple sites overlying the Ogallala Aquifer for the 2010-2012 period. In the first version of SCM-CESM, CESM will be used in standard mode (Community Atmospheric Model (CAM) coupled to a single instance of the Community Land Model (CLM)), secondly, CESM will be used in Super-Parameterized mode (SP-CESM), where a cloud resolving model (CRM consists of 32 atmospheric columns) replaces the standard CAM atmospheric parameterization and is coupled to a single instance of CLM, and thirdly, CESM is used in "Multi Instance" SP-CESM mode, where an instance of CLM is coupled to each CRM column of SP-CESM (32 CRM columns coupled to 32 instances of CLM). To assess the physical realism of the land-atmosphere feedbacks simulated at each site by all versions of SCM-CESM, differences in simulated energy and moisture fluxes will be computed between years for the 2010-2012 period, and will be compared to differences calculated using

A novel analytical solution for estimating aquifer properties within a horizontally anisotropic aquifer bounded by a stream

Science.gov (United States)

Huang, Yibin; Zhan, Hongbin; Knappett, Peter S. K.

2018-04-01

Past studies modeling stream-aquifer interaction commonly account for vertical anisotropy in hydraulic conductivity, but rarely address horizontal anisotropy, which may exist in certain sedimentary environments. If present, horizontal anisotropy will greatly impact stream depletion and the amount of recharge a pumped aquifer captures from the river. This scenario requires a different and somewhat more sophisticated mathematical approach to model and interpret pumping test results than previous models used to describe captured recharge from rivers. In this study, a new mathematical model is developed to describe the spatiotemporal distribution of drawdown from stream-bank pumping with a well screened across a horizontally anisotropic, confined aquifer, laterally bounded by a river. This new model is used to estimate four aquifer parameters including the magnitude and directions of major and minor principal transmissivities and storativity based on the observed drawdown-time curves within a minimum of three non-collinear observation wells. In order to approve the efficacy of the new model, a MATLAB script file is programmed to conduct a four-parameter inversion to estimate the four parameters of concern. By comparing the results of analytical and numerical inversions, the accuracy of estimated results from both inversions is acceptable, but the MATLAB program sometimes becomes problematic because of the difficulty of separating the local minima from the global minima. It appears that the new analytical model of this study is applicable and robust in estimating parameter values for a horizontally anisotropic aquifer laterally bounded by a stream. Besides that, the new model calculates stream depletion rate as a function of stream-bank pumping. Unique to horizontally anisotropic and homogeneous aquifers, the stream depletion rate at any given pumping rate depends closely on the horizontal anisotropy ratio and the direction of the principle transmissivities relative to

The integrated impacts of natural processes and human activities on groundwater salinization in the coastal aquifers of Beihai, southern China

Science.gov (United States)

Li, Qinghua; Zhang, Yanpeng; Chen, Wen; Yu, Shaowen

2018-03-01

Salinization in coastal aquifers is usually related to both seawater intrusion and water-rock interaction. The results of chemical and isotopic methods were combined to identify the origin and processes of groundwater salinization in Daguansha area of Beihai, southern China. The concentrations of the major ions that dominate in seawater (Cl-, Na+, Ca2+, Mg2+ and SO4 2- ), as well as the isotopic content and ratios (2H, 18O, 87Sr/86Sr and 13C), suggest that the salinization occurring in the aquifer of the coastal plain is related to seawater and that the prevailing hydrochemical processes are evaporation, mixing, dissolution and ion exchange. For the unconfined aquifer, groundwater salinization has occurred in an area that is significantly influenced by land-based sea farming. The integrated impacts of seawater intrusion from the Beibuwan Gulf and infiltration of seawater from the culture ponds are identified in the shallowest confined aquifer (I) in the middle of the area (site BBW2). Leakage from this polluted confined aquifer causes the salinization of groundwater in the underlying confined aquifer (II). At the coastal monitoring site (BBW3), confined aquifer I and lower confined aquifer II are heavily contaminated by seawater intrusion. The weak connectivity between the upper aquifers, and the seaward movement of freshwater, prevents saltwater from encroaching the deepest confined aquifer (III). A conceptual model is presented. Above all, understanding of the origin and processes of groundwater salinization will provide essential information for the planning and sustainable management of groundwater resources in this region.

Radionuclide transport in the Neogene aquifer system located in the environment of the Boom clay

International Nuclear Information System (INIS)

Gedeon, M.; Marivoet, J.; Vandersteen, K.

2012-01-01

Document available in extended abstract form only. In the framework the Belgian research program on the long term management of high-level and/or long-lived radioactive waste coordinated by ONDRAF/NIRAS, the Boom Clay is considered as a reference host rock for the geological disposal of high-level radioactive waste in NE-Belgium (Campine area). In the frame of the performance assessments of a disposal system located in the Boom Clay Formation, the transport of radionuclides diffusing through the clay barrier into the aquifers located above is modelled. The transport model for the Neogene aquifer is based on a series of groundwater flow models simulating the aquifer systems in the surroundings of the Boom Clay. This series of groundwater models include the regional north-eastern Belgium model simulating flow both above and below the Boom Clay, the recently updated deep-aquifer pumping model, simulating transient flow in the over-exploited aquifers below the Boom Clay and finally the catchment-scale Neogene aquifer model, simulating flow in the aquifer system above the Boom Clay. The Neogene aquifer system consists of two main aquifers. The Pliocene aquifer is located at the top, separated from the underlying Miocene aquifer by the Kasterlee Clay aquitard. The Miocene aquifer consists of three hydrostratigraphic units: the Diest, Berchem and Voort Formations; with the last two having a lower hydraulic conductivity than the Diest unit. The transport model for the Neogene aquifer represents a fraction of the catchment-scale Neogene aquifer model. It stretches from the local divide between the Grote and Kleine Nete Rivers up to the Kleine Nete River, representing the main model sink. The boundary conditions and the sources/sinks in the Pliocene aquifer are defined mostly by the surface water features, such as the rivers, brooks, lakes and canals. In the partially confined Miocene aquifer, the effect of the surface water features is dampened and the heads at the model

A Novel Analytical Solution for Estimating Aquifer Properties and Predicting Stream Depletion Rates by Pumping from a Horizontally Anisotropic Aquifer

Science.gov (United States)

Huang, Y.; Zhan, H.; Knappett, P.

2017-12-01

Past studies modeling stream-aquifer interactions commonly account for vertical anisotropy, but rarely address horizontal anisotropy, which does exist in certain geological settings. Horizontal anisotropy is impacted by sediment deposition rates, orientation of sediment particles and orientations of fractures etc. We hypothesize that horizontal anisotropy controls the volume of recharge a pumped aquifer captures from the river. To test this hypothesis, a new mathematical model was developed to describe the distribution of drawdown from stream-bank pumping with a well screened across a horizontally anisotropic, confined aquifer, laterally bounded by a river. This new model was used to determine four aquifer parameters including the magnitude and directions of major and minor principal transmissivities and storativity based on the observed drawdown-time curves within a minimum of three non-collinear observation wells. By comparing the aquifer parameters values estimated from drawdown data generated known values, the discrepancies of the major and minor transmissivities, horizontal anisotropy ratio, storativity and the direction of major transmissivity were 13.1, 8.8, 4, 0 and managers to exploit groundwater resource reasonably while protecting stream ecosystem.

Aquifer test interpretation using derivative analysis and diagnostic plots

Science.gov (United States)

Hernández-Espriú, Antonio; Real-Rangel, Roberto; Cortés-Salazar, Iván; Castro-Herrera, Israel; Luna-Izazaga, Gabriela; Sánchez-León, Emilio

2017-04-01

Pumping tests remain a method of choice to deduce fundamental aquifer properties and to assess well condition. In the oil and gas (O&G) industry, well testing has been the core technique in examining reservoir behavior over the last 50 years. The pressure derivative by Bourdet, it is perhaps, the most significant single development in the history of well test analysis. Recently, the so-called diagnostics plots (e.g. drawdown and drawdown derivative in a log-log plot) have been successfully tested in aquifers. However, this procedure is still underutilized by groundwater professionals. This research illustrates the applicability range, advantages and drawbacks (e.g. smoothing procedures) of diagnostic plots using field examples from a wide spectrum of tests (short/long tests, constant/variable flow rates, drawdown/buildup stages, pumping well/observation well) in dissimilar geological conditions. We analyze new and pre-existent aquifer tests in Mexico, USA, Canada, Germany, France and Saudi Arabia. In constant flow rate tests, our results show that derivative analysis is an easy, robust and powerful tool to assess near-borehole damage effects, formation heterogeneity, boundaries, flow regimes, infinite-acting radial stages, i.e., valid Theisian framework, and fracture-driven flow. In step tests, the effectiveness relies on high-frequency drawdown measurements. Moreover, we adapt O&G analytical solutions to cater for the conditions in groundwater systems. In this context, further parameters can be computed analytically from the plots, such as skin factor, head losses, wellbore storage, distance to the boundary, channel-aquifer and/or fracture zone width, among others. Therefore, diagnostic plots should be considered a mandatory tool for pumping tests analysis among hydrogeologists. This project has been supported by DGAPA (UNAM) under the research project PAPIIT IN-112815.

Anaerobic Transformation of Chlorinated Aliphatic Hydrocarbons in a Sand Aquifer Based on Spatial Chemical Distributions

Science.gov (United States)

Semprini, Lewis; Kitanidis, Peter K.; Kampbell, Don H.; Wilson, John T.

1995-04-01

We estimated the distribution of chlorinated aliphatic hydrocarbons (CAHs) from groundwater samples collected along three transects in a sand aquifer. Trichloroethylene (TCE) leaked and contaminated the aquifer probably more than a decade before we collected the measurements. The data show significant concentrations of TCE, cis-l,2-dichloroethylene (c-DCE), vinyl chloride (VC), and ethene. We attributed DCE, VC, and ethene to the reductive dehalogenation of TCE. The CAH concentrations varied significantly with depth and correlate with sulfate and methane concentrations. Anoxic aquifer conditions exist with methane present at relatively high concentrations at depth. High concentrations of TCE correspond with the absence of methane or low methane concentrations, whereas products of TCE dehalogenation are associated with higher methane concentrations and low sulfate concentrations. Indications are that the dechlorination of TCE and DCE to VC and ethene is associated with sulfate reduction and active methanogenesis. TCE dechlorination to DCE is likely occurring under the less reducing conditions of sulfate reduction, with further reductions to VC and ethene occurring under methanogenic conditions. We estimated that about 20% of TCE has dechlorinated to ethene. The analysis of the data enhanced our knowledge of natural in situ transformation and transport processes of CAHs.

Evaluation of conceptual and numerical models for arsenic mobilization and attenuation during managed aquifer recharge.

Science.gov (United States)

Wallis, Ilka; Prommer, Henning; Simmons, Craig T; Post, Vincent; Stuyfzand, Pieter J

2010-07-01

Managed Aquifer Recharge (MAR) is promoted as an attractive technique to meet growing water demands. An impediment to MAR applications, where oxygenated water is recharged into anoxic aquifers, is the potential mobilization of trace metals (e.g., arsenic). While conceptual models for arsenic transport under such circumstances exist, they are generally not rigorously evaluated through numerical modeling, especially at field-scale. In this work, geochemical data from an injection experiment in The Netherlands, where the introduction of oxygenated water into an anoxic aquifer mobilized arsenic, was used to develop and evaluate conceptual and numerical models of arsenic release and attenuation under field-scale conditions. Initially, a groundwater flow and nonreactive transport model was developed. Subsequent reactive transport simulations focused on the description of the temporal and spatial evolution of the redox zonation. The calibrated model was then used to study and quantify the transport of arsenic. In the model that best reproduced field observations, the fate of arsenic was simulated by (i) release via codissolution of arsenopyrite, stoichiometrically linked to pyrite oxidation, (ii) kinetically controlled oxidation of dissolved As(III) to As(V), and (iii) As adsorption via surface complexation on neo-precipitated iron oxides.

Sustainable Capture: Concepts for Managing Stream-Aquifer Systems.

Science.gov (United States)

Davids, Jeffrey C; Mehl, Steffen W

2015-01-01

Most surface water bodies (i.e., streams, lakes, etc.) are connected to the groundwater system to some degree so that changes to surface water bodies (either diversions or importations) can change flows in aquifer systems, and pumping from an aquifer can reduce discharge to, or induce additional recharge from streams, springs, and lakes. The timescales of these interactions are often very long (decades), making sustainable management of these systems difficult if relying only on observations of system responses. Instead, management scenarios are often analyzed based on numerical modeling. In this paper we propose a framework and metrics that can be used to relate the Theis concepts of capture to sustainable measures of stream-aquifer systems. We introduce four concepts: Sustainable Capture Fractions, Sustainable Capture Thresholds, Capture Efficiency, and Sustainable Groundwater Storage that can be used as the basis for developing metrics for sustainable management of stream-aquifer systems. We demonstrate their utility on a hypothetical stream-aquifer system where pumping captures both streamflow and discharge to phreatophytes at different amounts based on pumping location. In particular, Capture Efficiency (CE) can be easily understood by both scientists and non-scientist alike, and readily identifies vulnerabilities to sustainable stream-aquifer management when its value exceeds 100%. © 2014, National Ground Water Association.

Induced recharge of an artesian glacial-drift aquifer at Kalamazoo, Michigan

Science.gov (United States)

Reed, J.E.; Deutsch, Morris; Wiitala, S.W.

1966-01-01

As part of a program for managing its ground-water supply, the city of Kalamazoo has constructed induced-recharge facilities at the sites of several of its well fields. To determine the benefits of induced recharge in a water-management program, the U.S. Geological Survey, in cooperation with the city, conducted a series of field experiments at a city well field (Station 9). The 12 production wells at the test site penetrate about 160 feet of glacial drift, which can be separated into three general units a lower aquifer, an intervening confining layer, and an upper aquifer. Although the upper aquifer is not tapped by any of the municipal supply wells, it serves as a storage and transmission medium for water from the West Fork Portage Creek. The testing program consisted of four aquifer and three recharge tests. The aquifer tests show that the transmissibility of the upper and lower aquifers ranges from 50,000 to 100,000 gallons per day per foot and indicate that nearly 200 gpm (gallons per minute) leaks through the intervening aquiclude under nonpumping conditions. The object of the three recharge tests (tests 5, 6, and 7) was to observe the effects of induced recharge by varying conditions in the recharge channel. During the three recharge tests, 7 wells were pumped at a total rate averaging about 2,500 gpm. During test 5, inflow to the channel was shut off, and the water level in the channel was allowed to decline. Drawdowns measured during this test were used as a standard for comparison with drawdowns in tests 6 and 7. During test 6, the head in the recharge channel was maintained as constant as possible, and the inflow to the channel was measured. The rate of induced recharge, as indicated by the measured inflow, averaged about 300 gpm. Between tests 6 and 7, the area of the channel was increased from 27,000 to 143,000 square feet. During test 7, the head in the channel was again maintained as constant as possible, but the inflow to the larger channel

Sensitivity of the Gravity Recovery and Climate Experiment (GRACE) to the complexity of aquifer systems for monitoring of groundwater

Science.gov (United States)

Katpatal, Yashwant B.; Rishma, C.; Singh, Chandan K.

2018-05-01

The Gravity Recovery and Climate Experiment (GRACE) satellite mission is aimed at assessment of groundwater storage under different terrestrial conditions. The main objective of the presented study is to highlight the significance of aquifer complexity to improve the performance of GRACE in monitoring groundwater. Vidarbha region of Maharashtra, central India, was selected as the study area for analysis, since the region comprises a simple aquifer system in the western region and a complex aquifer system in the eastern region. Groundwater-level-trend analyses of the different aquifer systems and spatial and temporal variation of the terrestrial water storage anomaly were studied to understand the groundwater scenario. GRACE and its field application involve selecting four pixels from the GRACE output with different aquifer systems, where each GRACE pixel encompasses 50-90 monitoring wells. Groundwater storage anomalies (GWSA) are derived for each pixel for the period 2002 to 2015 using the Release 05 (RL05) monthly GRACE gravity models and the Global Land Data Assimilation System (GLDAS) land-surface models (GWSAGRACE) as well as the actual field data (GWSAActual). Correlation analysis between GWSAGRACE and GWSAActual was performed using linear regression. The Pearson and Spearman methods show that the performance of GRACE is good in the region with simple aquifers; however, performance is poorer in the region with multiple aquifer systems. The study highlights the importance of incorporating the sensitivity of GRACE in estimation of groundwater storage in complex aquifer systems in future studies.

Mapping groundwater level and aquifer storage variations from InSAR measurements in the Madrid aquifer, Central Spain

Science.gov (United States)

Béjar-Pizarro, Marta; Ezquerro, Pablo; Herrera, Gerardo; Tomás, Roberto; Guardiola-Albert, Carolina; Ruiz Hernández, José M.; Fernández Merodo, José A.; Marchamalo, Miguel; Martínez, Rubén

2017-04-01

Groundwater resources are under stress in many regions of the world and the future water supply for many populations, particularly in the driest places on Earth, is threatened. Future climatic conditions and population growth are expected to intensify the problem. Understanding the factors that control groundwater storage variation is crucial to mitigate its adverse consequences. In this work, we apply satellite-based measurements of ground deformation over the Tertiary detritic aquifer of Madrid (TDAM), Central Spain, to infer the spatio-temporal evolution of water levels and estimate groundwater storage variations. Specifically, we use Persistent Scatterer Interferometry (PSI) data during the period 1992-2010 and piezometric time series on 19 well sites covering the period 1997-2010 to build groundwater level maps and quantify groundwater storage variations. Our results reveal that groundwater storage loss occurred in two different periods, 1992-1999 and 2005-2010 and was mainly concentrated in a region of ∼200 km2. The presence of more compressible materials in that region combined with a long continuous water extraction can explain this volumetric deficit. This study illustrates how the combination of PSI and piezometric data can be used to detect small aquifers affected by groundwater storage loss helping to improve their sustainable management.

Effects of climate change and population growth on the transboundary Santa Cruz aquifer

Science.gov (United States)

Scott, Christopher A.; Megdal, Sharon; Oroz, Lucas Antonio; Callegary, James; Vandervoet, Prescott

2012-01-01

The USA and Mexico have initiated comprehensive assessment of 4 of the 18 aquifers underlying their 3000 km border. Binational management of groundwater is not currently proposed. University and agency researchers plus USA and Mexican federal, state, and local agency staff have collaboratively identified key challenges facing the Santa Cruz River Valley Aquifer located between the states of Arizona and Sonora. The aquifer is subject to recharge variability, which is compounded by climate change, and is experiencing growing urban demand for groundwater. In this paper, we briefly review past, current, and projected pressures on Santa Cruz groundwater. We undertake first-order approximation of the relative magnitude of climate change and human demand drivers on the Santa Cruz water balance. Global circulation model output for emissions scenarios A1B, B1, and A2 present mixed trends, with annual precipitation projected to vary by ±20% over the 21st century. Results of our analysis indicate that urban water use will experience greater percentage change than climate-induced recharge (which remains the largest single component of the water balance). In the Mexican portion of the Santa Cruz, up to half of future total water demand will need to be met from non-aquifer sources. In the absence of water importation and with agricultural water use and rights increasingly appropriated for urban demand, wastewater is increasingly seen as a resource to meet urban demand. We consider decision making on both sides of the border and conclude by identifying short- and longer-term opportunities for further binational collaboration on transboundary aquifer assessment.

Inventory and review of aquifer storage and recovery in southern Florida

Science.gov (United States)

Reese, Ronald S.

2002-01-01

publications > water resources investigations > report 02-4036 US Department of the Interior US Geological Survey WRI 02-4036Inventory and Review of Aquifer Storage and Recovery in Southern Florida By Ronald S. ReeseTallahassee, Florida 2002 prepared as part of the U.S. Geological Survey Place-Based Studies Program ABSTRACT Abstract Introduction Inventory of Data Case Studies Summary References Tables Aquifer storage and recovery in southern Florida has been proposed on an unprecedented scale as part of the Comprehensive Everglades Restoration Plan. Aquifer storage and recovery wells were constructed or are under construction at 27 sites in southern Florida, mostly by local municipalities or counties located in coastal areas. The Upper Floridan aquifer, the principal storage zone of interest to the restoration plan, is the aquifer being used at 22 of the sites. The aquifer is brackish to saline in southern Florida, which can greatly affect the recovery of the freshwater recharged and stored.Well data were inventoried and compiled for all wells at most of the 27 sites. Construction and testing data were compiled into four main categories: (1) well identification, location, and construction data; (2) hydraulic test data; (3) ambient formation water-quality data; and (4) cycle testing data. Each cycle during testing or operation includes periods of recharge of freshwater, storage, and recovery that each last days or months. Cycle testing data include calculations of recovery efficiency, which is the percentage of the total amount of potable water recharged for each cycle that is recovered.Calculated cycle test data include potable water recovery efficiencies for 16 of the 27 sites. However, the number of cycles at most sites was limited; except for two sites, the highest number of cycles was five. Only nine sites had a recovery efficiency above 10 percent for the first cycle, and 10 sites achieved a recovery efficiency above 30 percent during at least one cycle. The

Tritium-helium 3 dating under complex conditions in hydraulically stressed areas of a buried-valley aquifer

Science.gov (United States)

Shapiro, Stephanie Dunkle; Rowe, Gary L.; Schlosser, Peter; Ludin, Andrea; Stute, Martin

1998-01-01

The 3H-3He dating method is applied in a buried-valley aquifer near Dayton, Ohio. The study area is large, not all sampling locations lie along well-defined flow paths, and existing wells with variable screen lengths and diameters are used. Reliable use of the method at this site requires addressing several complications: (1) The flow system is disturbed because of high pumping rates and induced infiltration; (2) tritium contamination is present in several areas of the aquifer; and (3) radiogenic helium concentrations are elevated in a significant number of the wells. The 3H-3He ages are examined for self-consistency by comparing the reconstructed tritium evolution to the annual weighted tritium measured in precipitation; deviations result from dispersion, tritium contamination, and mixing. 3H-3He ages are next examined for consistency with chlorofluorocarbon ages; the agreement is poor because of degradation of CFCs. Finally, the 3H-3He ages are examined for consistency with the current understanding of local hydrologic processes; the ages are generally supported by hydrogeologic data and the results of groundwater flow modeling coupled with particle-tracking analyses.

Global assessment of coastal aquifer state and its vulnerability respect to Sea Water Intrusion. Application to several Mediterranean Coastal Aquifers.

Science.gov (United States)

Baena, Leticia; Pulido-Velazquez, David; Renau-Pruñonosa, Arianna; Morell, Ignacio

2017-04-01

In this research we propose a method for a global assessment of coastal aquifer state and its vulnerability to Sea Water Intrusion (SWI). It is based on two indices, the MART index, which summarize the global significance of the SWI phenomenon, and the L_GALDIT for a lumped assessment of the vulnerability to SWI. Both of them can be useful as a tool to assess coastal groundwater bodies in risk of not achieving good status in accordance with the Water Framework Directive (WFD, 2000) and to identify possible management alternative to reduce existing impacts. They can be obtained even from a reduced number of data (in the MART case only depend on the geometry and available aquifer state data) with simple calculations, which have been implemented in a general GIS tool that can be easily applied to other case studies. The MART index in an aquifer is related with the total mass of chloride in the aquifer due to sea water intrusion and can be obtained by simple linear operations of volume and concentrations that can be deduced from a schematic conceptual cross-section approach (orthogonal to the shore line) defined to summarize the intrusion volume in the aquifer. At a certain historical time, this representative aquifer cross-section can be defined in a systhematic way from the aquifer geometry, the specific yield, and the hydraulic head and chloride concentration fields that can be deduced from the available information by using appropriate interpolation methods. Following the proposed procedure we will finally obtain a summary of the historical significance of the SWI in an aquifer at different spatial resolution: 3D salinity concentration maps, 2D representative conceptual cross-section of intrusion and the MART lumped significance index. The historical evolution of the MART can be employed to perform a global assessment of the resilience and trends of global significance of the SWI in an aquifer. It can be useful to compare the significance of intrusion problems in

Numerical modeling and sensitivity analysis of seawater intrusion in a dual-permeability coastal karst aquifer with conduit networks

Directory of Open Access Journals (Sweden)

Z. Xu

2018-01-01

Full Text Available Long-distance seawater intrusion has been widely observed through the subsurface conduit system in coastal karst aquifers as a source of groundwater contaminant. In this study, seawater intrusion in a dual-permeability karst aquifer with conduit networks is studied by the two-dimensional density-dependent flow and transport SEAWAT model. Local and global sensitivity analyses are used to evaluate the impacts of boundary conditions and hydrological characteristics on modeling seawater intrusion in a karst aquifer, including hydraulic conductivity, effective porosity, specific storage, and dispersivity of the conduit network and of the porous medium. The local sensitivity analysis evaluates the parameters' sensitivities for modeling seawater intrusion, specifically in the Woodville Karst Plain (WKP. A more comprehensive interpretation of parameter sensitivities, including the nonlinear relationship between simulations and parameters, and/or parameter interactions, is addressed in the global sensitivity analysis. The conduit parameters and boundary conditions are important to the simulations in the porous medium because of the dynamical exchanges between the two systems. The sensitivity study indicates that salinity and head simulations in the karst features, such as the conduit system and submarine springs, are critical for understanding seawater intrusion in a coastal karst aquifer. The evaluation of hydraulic conductivity sensitivity in the continuum SEAWAT model may be biased since the conduit flow velocity is not accurately calculated by Darcy's equation as a function of head difference and hydraulic conductivity. In addition, dispersivity is no longer an important parameter in an advection-dominated karst aquifer with a conduit system, compared to the sensitivity results in a porous medium aquifer. In the end, the extents of seawater intrusion are quantitatively evaluated and measured under different scenarios with the variabilities of

Kinetics and Efficiency of H2O2 Activation by Iron-Containing Minerals and Aquifer Materials

Science.gov (United States)

Pham, Anh Le-Tuan; Doyle, Fiona M.; Sedlak, David L.

2014-01-01

To gain insight into factors that control H2O2 persistence and ˙OH yield in H2O2-based in situ chemical oxidation systems, the decomposition of H2O2 and transformation of phenol were investigated in the presence of iron-containing minerals and aquifer materials. Under conditions expected during remediation of soil and groundwater, the stoichiometric efficiency, defined as the amount of phenol transformed per mole of H2O2 decomposed, varied from 0.005 to 0.28%. Among the iron-containing minerals, iron oxides were 2 to 10 times less efficient in transforming phenol than iron-containing clays and synthetic iron-containing catalysts. In both iron-containing mineral and aquifer materials systems, the stoichiometric efficiency was inversely correlated with the rate of H2O2 decomposition. In aquifer materials systems, the stoichiometric efficiency was also inversely correlated with the Mn content, consistent with the fact that the decomposition of H2O2 on manganese oxides does not produce ˙OH. Removal of iron and manganese oxide coatings from the surface of aquifer materials by extraction with citrate-bicarbonate-dithionite slowed the rate of H2O2 decomposition on aquifer materials and increased the stoichiometric efficiency. In addition, the presence of 2 mM of dissolved SiO2 slowed the rate of H2O2 decomposition on aquifer materials by over 80% without affecting the stoichiometric efficiency. PMID:23047055

Sorption of activation products on London clay and Dungeness aquifer gravel

International Nuclear Information System (INIS)

Baston, G.M.N.; Berry, J.A.; Littleboy, A.K.; Pilkington, N.J.

1992-01-01

The sortpion of a series of activation-product radionuclides onto London clay and Dungeness aquifer gravel from the nuclear reactor sites at Bradwell and Dungeness, has been examined. Batch sorption and through-diffusion experiments with clay determined chlorine as the chloride ion to be effectively non-sorbing; calcium to be weakly sorbing, whereas cobalt, nickel, niobium and samarium were moderately to strongly sorbing and silver was strongly sorbing. Distribution ratios (R D values) for Nb, Sm and Ag were found to have a strong dependence on the liquid-solid separation technique employed. The presence of high concentrations of calcium hydroxide led to lower values of R D for radioactive Ca but higher R D values for Sm and Ag. The sorption of Ni showed no apparent dependence on groundwater composition at low levels of dissolved organic carbon (DOC). The values of R D for Co decreased as the DOC content was increased by addition of humic materials. Batch sorption studies with aquifer gravel demonstrated that Ca is weakly sorbing whereas Nb, Ag and Eu are moderately to strongly sorbing. R D values for Ca and for Ag under neutral pH conditions show little sensitivity to the liquid/solid separation technique used. However, R D values for Nb and Eu under neutral pH conditions and for Ag in alkaline solution (pH = 11 - 12) show a marked effect. The aquifer gravel was found to be highly inhomogeneous unlike the clay and sorption was greatest on samples with a high proportion of sand, reflecting the clay mineral content. (orig.)

Testing water pollution in a two layer aquifer

OpenAIRE

García León, Manuel; Lin Ye, Jue

2011-01-01

Water bodies around urban areas may be polluted with chemical elements from urban or industrial activities. We study the case of underground water pollution. This is a serious problem, since under- ground water is high qualified drinkable water in a world where this natural resource is increasingly reduced. This study is focused on a two-layer aquifer. If the superficial layer is contaminated, the deeper layer could be spoiled as well. This contribution checks the equality of the mean or c...

Comparison of groundwater flow in Southern California coastal aquifers

Science.gov (United States)

Hanson, Randall T.; Izbicki, John A.; Reichard, Eric G.; Edwards, Brian D.; Land, Michael; Martin, Peter

2009-01-01

Development of the coastal aquifer systems of Southern California has resulted in overdraft, changes in streamflow, seawater intrusion, land subsidence, increased vertical flow between aquifers, and a redirection of regional flow toward pumping centers. These water-management challenges can be more effectively addressed by incorporating new understanding of the geologic, hydrologic, and geochemical setting of these aquifers.

Aquifer test at well SMW-1 near Moenkopi, Arizona

Science.gov (United States)

Carruth, Rob; Bills, Donald J.

2012-01-01

The Hopi villages of Lower Moencopi and Upper Moenkopi are on the Hopi Indian Reservation south of Tuba City in northern Arizona. These adjacent Hopi villages, located west and north of the confluence of Pasture Canyon Wash and Moenkopi Wash, are dependent on groundwater withdrawals from three wells that penetrate the N aquifer and from two springs that discharge from the N aquifer. The N aquifer is the principal aquifer in this region of northern Arizona and is composed of thick beds of sandstone between less permeable layers of siltstone and mudstone. The fine-grained character of the N aquifer inhibits rapid movement of water and large yields to wells; however, the aquifer is moderately productive at yields generally less than 25 gallons per minute in the study area. In recent years, the water level has declined in the three public-supply wells and the flow from the springs has decreased, causing concern that the current water supply will not be able to accommodate peak demand and allow for residential and economic growth. In addition to the challenge imposed by declining groundwater levels, the water-supply wells and springs are located about 2 miles downgradient from the Tuba City Landfill site where studies are ongoing to determine if uranium and other metals in groundwater beneath the landfill are higher than regional concentrations in the N aquifer. In August 2008, the U.S. Geological Survey, in cooperation with the Hopi Tribe, conducted an aquifer test on well SMW-1, designed to help the Hopi Tribe determine the potential yield and water quality of the N aquifer south of Moenkopi Wash as a possible source of additional water supply. Well SMW-1 was drilled south of Moenkopi Wash to a depth of 760 feet below land surface before being backfilled and cased to about 300 feet. The well penetrates, in descending order, the Navajo Sandstone and the Kayenta Formation, both units of the N aquifer. The pre-test water level in the well was 99.15 feet below land

Uranium partitioning under acidic conditions in a sandy soil aquifer

International Nuclear Information System (INIS)

Johnson, W.H.; Serkiz, S.M.; Johnson, L.M.

1995-01-01

The partitioning of uranium in an aquifer down gradient of two large mixed waste sites was examined with respect to the solution and soil chemistry (e.g., pH redox potential and contaminant concentration) and aqueous-phase chemical speciation. This involved generation of field-derived, batch sorption, and reactive mineral surface sorption data. Field-derived distribution coefficients for uranium at these waste sites were found to vary between 0.40 and 15,000. Based on thermodynamic speciation modeling and a comparison of field and laboratory data, gibbsite is a potential reactive mineral surface present in modified soils at the sites. Uranium partitioning data are presented from field samples and laboratory studies of background soil and the mineral surface gibbsite. Mechanistic and empirical sorption models fit to the field-derived uranium partitioning data show an improvement of over two orders of magnitude, as measured by the normalized sum of errors squared, when compared with the single K d model used in previous risk work. Models fit to batch sorption data provided a better fit of sorbed uranium than do models fit to the field-derived data

Regeneration of a confined aquifer after redevelopment and decommission of artesian wells, example from Grafendorf aquifer (Styria, Austria)

Science.gov (United States)

Mehmedovski, Nudzejma; Winkler, Gerfried

2016-04-01

Water is essential for life and it is therefore necessary to protect drinking water sustainably. Compared to shallow groundwater, deeper groundwater is especially important due to its characteristic tendency to remain extensively unaffected by environmental impacts. Thus, the uncontrolled waste of this valuable resource has to be avoided. A lot of artesian wells have been established in Grafendorf bei Hartberg (Styria, Austria). Almost all wells were not state-of-the art. As a result the different aquifer horizons began to intermix. Additionally some of the artesian wells had a permanent free overflow and the water was not even used. Consequently, since 1950, where the mean discharge of 37 wells was 0,334 l/s per well, the discharge has decreased to 0,090 l/s until 2013, which means a decline of about 75 %. As a reaction to these declines a decommissioning campaign was conducted where 69 artesian wells have been closed by injecting a cement-bentonite suspension (ratio 3:1). The Grafendorf aquifer is situated in the Styrian Basin and consists of 5 separated artesian horizons in Neogene sediments. These artesian horizons range from 42 m (1st horizon) to 176 m (5th horizon) and mostly consist of sand, partly of fine/medium/coarse gravel and partially with minor clay content. In order to analyse the reaction of the Grafendorf aquifer to these redevelopments, 5 monitoring wells could be used for the analysis. Some monitoring wells include different aquifer horizons and hydraulically short cut them. Thus, in this work the analysis focus on the general trend of the whole aquifer system neglecting the individual interactions between the different aquifers. In a first investigation step the hydraulic properties of the aquifer system has been determined using pumping tests which were analysed with different analytical solutions with the software AQTESOLV. Overall the pumping test solutions hardly differ in the transmissivity and hydraulic conductivity. On the contrary the

Transient well flow in vertically heterogeneous aquifers

Science.gov (United States)

Hemker, C. J.

1999-11-01

A solution for the general problem of computing well flow in vertically heterogeneous aquifers is found by an integration of both analytical and numerical techniques. The radial component of flow is treated analytically; the drawdown is a continuous function of the distance to the well. The finite-difference technique is used for the vertical flow component only. The aquifer is discretized in the vertical dimension and the heterogeneous aquifer is considered to be a layered (stratified) formation with a finite number of homogeneous sublayers, where each sublayer may have different properties. The transient part of the differential equation is solved with Stehfest's algorithm, a numerical inversion technique of the Laplace transform. The well is of constant discharge and penetrates one or more of the sublayers. The effect of wellbore storage on early drawdown data is taken into account. In this way drawdowns are found for a finite number of sublayers as a continuous function of radial distance to the well and of time since the pumping started. The model is verified by comparing results with published analytical and numerical solutions for well flow in homogeneous and heterogeneous, confined and unconfined aquifers. Instantaneous and delayed drainage of water from above the water table are considered, combined with the effects of partially penetrating and finite-diameter wells. The model is applied to demonstrate that the transient effects of wellbore storage in unconfined aquifers are less pronounced than previous numerical experiments suggest. Other applications of the presented solution technique are given for partially penetrating wells in heterogeneous formations, including a demonstration of the effect of decreasing specific storage values with depth in an otherwise homogeneous aquifer. The presented solution can be a powerful tool for the analysis of drawdown from pumping tests, because hydraulic properties of layered heterogeneous aquifer systems with

Managed Aquifer Recharge in Italy: present and prospects.

Science.gov (United States)

Rossetto, Rudy

2015-04-01

On October the 3rd 2014, a one-day Workshop on Managed Aquifer Recharge (MAR) experiences in Italy took place at the GEOFLUID fair in Piacenza. It was organized within the framework of the EIP AG 128 - MAR Solutions - Managed Aquifer Recharge Strategies and Actions and the EU FPVII MARSOL. The event aimed at showcasing present experiences on MAR in Italy while at the same time starting a network among all the Institutions involved. In this contribution, we discuss the state of MAR application in Italy and summarize the outcomes of that event. In Italy aquifer recharge is traditionally applied unintentionally, by increasing riverbank filtration or because of excess irrigation. A certain interest for artificial recharge of aquifers arose at the end of the '70s and the beginning of the '80s and tests have been carried out in Tuscany, Veneto and Friuli Venezia Giulia. During the last years some projects on aquifer recharge were co-financed by the European Commission mainly through the LIFE program. Nearly all of them use the terminology of artificial recharge instead of MAR. They are: - TRUST (Tool for regional - scale assessment of groundwater storage improvement in adaptation to climate change, LIFE07 ENV/IT/000475; Marsala 2014); - AQUOR (Implementation of a water saving and artificial recharging participated strategy for the quantitative groundwater layer rebalance of the upper Vicenza's plain - LIFE 2010 ENV/IT/380; Mezzalira et al. 2014); - WARBO (Water re-born - artificial recharge: innovative technologies for the sustainable management of water resources, LIFE10 ENV/IT/000394; 2014). While the TRUST project dealt in general with aquifer recharge, AQUOR and WARBO focused essentially on small scale demonstration plants. Within the EU FPVII-ENV-2013 MARSOL project (Demonstrating Managed Aquifer Recharge as a Solution to Water Scarcity and Drought; 2014), a dedicated monitoring and decision support system is under development to manage recharge at a large scale

On the origins of hypersaline groundwater in the Nile Delta Aquifer

Science.gov (United States)

van Engelen, Joeri; Oude Essink, Gualbert H. P.; Kooi, Henk; Bierkens, Marc F. P.

2017-04-01

The fresh groundwater resources in the Nile Delta, Egypt, are of eminent socio-economic importance. These resources are under major stress due to population growth, the anticipated sea level rise and increased groundwater extraction rates, making fresh water availability the most challenging issue in this area. Up till now, numerous groundwater studies mainly focused on sea water intrusion on the top 100m of the groundwater system and assumed salinities not exceeding that of Mediterranean sea water, as there was no knowledge on groundwater in the deeper coastal parts of the Quaternary Nile Delta aquifer (that ranges up to 1000m depth). Recently, however, the Egyptian Research Institute for Groundwater (RIGW) collected salinity measurements and found a widespread occurrence of "hypersaline" groundwater: groundwater with salinities largely exceeding that of sea water at 600m depth (Nofal et al., 2015). This hypersaline groundwater greatly influences flow patterns and the fresh water potential of the aquifer. This research focuses on the origins of the hypersaline groundwater and the possible processes causing its transport. We consider all relevant salinization processes in the Nile Delta aquifer, over a time domain of up to 2.5 million years, which is the time span in which the aquifer got deposited. The following hypotheses were investigated with a combination of analytical solutions and numerical modelling: upward salt transport due to a) molecular diffusion, b) thermal buoyancy, c) consolidation-induced advection and dispersion, or downward transport due to d) composition buoyancy (salt inversion). We conclude that hypotheses a) and b) can be rejected, but c) and d) are both possible with the available information. An enhanced chemical analysis is suggested for further research, to determine the origins of this hypersaline water. This information in combination with the conclusions drawn in this research will give more insight in the potential amount of non

Elevated naturally occurring arsenic in a semiarid oxidizing system, Southern High Plains aquifer, Texas, USA

International Nuclear Information System (INIS)

Scanlon, B.R.; Nicot, J.P.; Reedy, R.C.; Kurtzman, D.; Mukherjee, A.; Nordstrom, D.K.

2009-01-01

High groundwater As concentrations in oxidizing systems are generally associated with As adsorption onto hydrous metal (Al, Fe or Mn) oxides and mobilization with increased pH. The objective of this study was to evaluate the distribution, sources and mobilization mechanisms of As in the Southern High Plains (SHP) aquifer, Texas, relative to those in other semiarid, oxidizing systems. Elevated groundwater As levels are widespread in the southern part of the SHP (SHP-S) aquifer, with 47% of wells exceeding the current EPA maximum contaminant level (MCL) of 10 μg/L (range 0.3-164 μg/L), whereas As levels are much lower in the north (SHP-N: 9% ≥ As MCL of 10 μg/L; range 0.2-43 μg/L). The sharp contrast in As levels between the north and south coincides with a change in total dissolved solids (TDS) from 395 mg/L (median north) to 885 mg/L (median south). Arsenic is present as arsenate (As V) in this oxidizing system and is correlated with groundwater TDS (Spearman's ρ = 0.57). The most likely current source of As is sorbed As onto hydrous metal oxides based on correlations between As and other oxyanion-forming elements (V, ρ = 0.88; Se, ρ = 0.54; B, ρ = 0.51 and Mo, ρ = 0.46). This source is similar to that in other oxidizing systems and constitutes a secondary source; the most likely primary source being volcanic ashes in the SHP aquifer or original source rocks in the Rockies, based on co-occurrence of As and F (ρ = 0.56), oxyanion-forming elements and SiO 2 (ρ = 0.41), which are found in volcanic ashes. High groundwater As concentrations in some semiarid oxidizing systems are related to high evaporation. Although correlation of As with TDS in the SHP aquifer may suggest evaporative concentration, unenriched stable isotopes (δ 2 H: -65 to -27; δ 18 O: -9.1 to -4.2) in the SHP aquifer do not support evaporation. High TDS in the SHP aquifer is most likely related to upward movement of saline water from the underlying Triassic Dockum aquifer. Mobilization

Simulation of saltwater movement in the Floridan aquifer system, Hilton Head Island, South Carolina

Science.gov (United States)

Bush, Peter W.

1988-01-01

Freshwater to supply Hilton Head Island, S.C., is obtained from the upper permeable zone of the Upper Floridan aquifer. Long-term pumping at Savannah, Ga., and the steadily increasing pumping on Hilton Head Island, have lowered Upper Floridan heads near the center of the island from about 10 feet above sea level to about 6 to 7 feet below sea level. The seaward hydraulic gradient that existed before pumping began has been reversed, thus increasing the potential for saltwater intrusion. Simulations of predevelopment, recent, and future ground-water flow in the Floridan aquifer system beneath the north end of Hilton Head Island and Port Royal Sound are presented. A finite-element model for fluid-density-dependent ground-water flow and solute transport was used in cross section. The general configuration of the simulated predevelopment flowfield is typical of a coastal aquifer having a seaward gradient in the freshwater. The freshwater flows toward Port Royal Sound over an intruding wedge of saltwater. The simulated flowfield at the end of 1983 shows that ground water in the Floridan aquifer system beneath most of Hilton Head Island has reversed its predevelopment direction and is moving toward Savannah. The distribution of chloride concentrations, based on simulation at the end of 1983, is about the same as the predevelopment distribution of chloride concentrations obtained from simulation. Results of two 50-year simulations from 1983 to 2034 suggest that there will be no significant threat of saltwater intrusion into the upper permeable zone of the Upper Floridan aquifer if heads on Hilton Head Island remain at current levels for the next 45 to 50 years. However, if head decline continues at the historical rate, any flow that presently occurs from the north end of the island toward Port Royal Sound will cease, allowing lateral intrusion of saltwater to proceed. Even under these conditions, chloride concentrations in the upper permeable zone of the Upper Floridan

Determination of Background Uranium Concentration in the Snake River Plain Aquifer under the Idaho National Engineering and Environmental Laboratory's Radioactive Waste Management Complex

International Nuclear Information System (INIS)

Molly K. Leecaster; L. Don Koeppen; Gail L. Olson

2003-01-01

Uranium occurs naturally in the environment and is also a contaminant that is disposed of at the Radioactive Waste Management Complex (RWMC) at the Idaho National Engineering and Environmental Laboratory. To determine whether uranium concentrations in the Snake River Plain Aquifer, which underlies the laboratory, are elevated as a result of migration of anthropogenic uranium from the Subsurface Disposal Area in the RWMC, uranium background concentrations are necessary. Guideline values are calculated for total uranium, 234U, 235U, and 238U from analytical results from up to five datasets. Three of the datasets include results of samples analyzed using isotope dilution thermal ionization mass spectrometry (ID-TIMS) and two of the datasets include results obtained using alpha spectrometry. All samples included in the statistical testing were collected from aquifer monitoring wells located within 10 miles of the RWMC. Results from ID-TIMS and alpha spectrometry are combined when the data are not statistically different. Guideline values for total uranium were calculated using four of the datasets, while guideline values for 234U were calculated using only the alpha spectrometry results (2 datasets). Data from all five datasets were used to calculate 238U guideline values. No limit is calculated for 235U because the ID-TIMS results are not useful for comparison with routine monitoring data, and the alpha spectrometry results are too close to the detection limit to be deemed accurate or reliable for calculating a 235U guideline value. All guideline values presented represent the upper 95% coverage 95% confidence tolerance limits for background concentration. If a future monitoring result is above this guideline, then the exceedance will be noted in the quarterly monitoring report and assessed with respect to other aquifer information. The guidelines (tolerance limits) for total U, 234U, and 238U are 2.75 pCi/L, 1.92 pCi/L, and 0.90 pCi/L, respectively

Geochemical approach of the salinization mechanisms of coastal aquifers - 14C - 226Ra chronologies

International Nuclear Information System (INIS)

Barbecot, F.

1999-11-01

Through time, coastal aquifers which constitute a great part of available fresh water resources from sedimentary basins in France, were submitted to changes in hydraulic gradients and hydrodynamic properties mainly due to discharge/recharge phases in response to sea level variations and/or anthropic forcing. Performed in the framework of the European program PALAEAUX ('Management of coastal aquifers in Europe, paleo-waters and natural controls'), this work aimed to understand the salinization process originating from the recharge/discharge conditions and recognized in three study aquifers: the calcareous Dogger aquifers along the Channel (Caen area), and the Atlantic coast (Marais Poitevin), and the Astian sandy aquifer (Cap d'Agde). Besides the conventional hydrogeological and hydrochemical methods, the main tools used are those of isotope geochemistry. For the three sites, the modern, fresh groundwaters are marked by the anthropisation of the recharge area. The evolution of isotopic signatures along a flow path depending on the mineralogy of the aquifer matrix, is linked to water-rock interactions such as cation exchange, and equilibrium with aluminosilicates. For the three study sites, the modern fresh groundwaters are marked by the anthropisation of the recharge area. The evolution of isotopic signatures along a flow path depending on the mineralogy of the aquifer matrix, is linked to water-rock interactions such as cation exchange, and equilibrium with aluminosilicates. Residence times of these fresh groundwater are from Present (Atlantic site) up to the 14 C detection limit (Channel site). Groundwater of the Astian aquifer belongs to Holocene, as determined by both 14 C and 226 Ra. From Present to 3 ka, 14 C and 226 Ra ages are coherent. Beyond, the discrepancy observed can be associated to the under-estimation of in- situ 226 Ra production, but more likely, to the 'buffer' effect of the matrix with respect to the 14 C isotopic equilibration. The salty waters

Response strategies for the Great Plains: Canadian and U.S. perspectives

International Nuclear Information System (INIS)

Jackson, C.I.

1991-01-01

From a policy point of view, the sharpest contrast between the five Great Plains states and the three Canadian provinces is the much greater significance of the Prairie provinces in Canadian life and national policymaking. The population of the Prairie provinces is substantial, and continues to grow steadily, with most growth concentrated in urban areas. A significant climate change issue in the boreal forest will be the impact of fire, as the forest is fire and insect dominated. The American solution to low precipitation, irrigation, is currently of relatively small importance on the Canadian Prairies. The main indication of general circulation models is that summer evapotranspiration will be more substantial than modest increases in precipitation, and while irrigation development is possible, there is no Canadian equivalent to the Ogallala aquifer. Adjustment or adaptation is as likely to mean adaptation to social and economic stress as much as to climate stress. Nebraska may provide a model for changes required to deal with climate warming, with a substantial problem area, substantial urban centers, and an aquifer recharge rate comparable with extraction rates. 13 refs

Hydro-geological properties of the Savian aquifer in the county Obrenovac

Directory of Open Access Journals (Sweden)

Stojadinović Dušan D.

2005-01-01

Full Text Available The paper presents a description of hydrogeological researches of alluvial layers of the Sava River in the area of the source "Vić Bare" near Obrenovac. This source supplies groundwater to that town. The depth of these layers amounts to 25 m. With regard to collecting capacity, the most significant are gravel-sand sediments of high filtration properties. Their average depth amounts to about 13 m with the underlying layer made of Pleistocene clays. Compact aquifer is formed within these sediments and it refills partly from the Sava River at places where river cuts its channel into the gravel-sand layer. The analysis of the groundwater regime in the riparian area points out that groundwater levels follow stages of the Sava River. Such an influence lessens with the distance. Established hydraulic connection between the river and the aquifer enables its permanent replenishment. On the other hand, due to certain pollutions this river flow might bring along, it represents a potential danger. Those pollutions could enter water-bearing layer of the aquifer as well as the exploitation well of the source. Such presumptions have been confirmed in the experiment of pollution transport carried out in the water-bearing layer. Unabsorbable chloride was used as a tracer whose movement velocity through exploitation well proved that there were real possibilities of intrusion of aggressive pollutants into the water-bearing layer and into the aquifer as well. Therefore, the protection of the source must be in the function of the protection of surface waters.

Assessing the recharge of a coastal aquifer using physical observations, tritium, groundwater chemistry and modelling.

Science.gov (United States)

Santos, Isaac R; Zhang, Chenming; Maher, Damien T; Atkins, Marnie L; Holland, Rodney; Morgenstern, Uwe; Li, Ling

2017-02-15

Assessing recharge is critical to understanding groundwater and preventing pollution. Here, we investigate recharge in an Australian coastal aquifer using a combination of physical, modelling and geochemical techniques. We assess whether recharge may occur through a pervasive layer of floodplain muds that was initially hypothesized to be impermeable. At least 59% of the precipitation volume could be accounted for in the shallow aquifer using the water table fluctuation method during four significant recharge events. Precipitation events rates were estimated in the area underneath the floodplain clay layer rather than in the sandy area. A steady-state chloride method implied recharge rates of at least 200mm/year (>14% of annual precipitation). Tritium dating revealed long term net vertical recharge rates ranging from 27 to 114mm/year (average 58mm/year) which were interpreted as minimum net long term recharge. Borehole experiments revealed more permeable conditions and heterogeneous infiltration rates when the floodplain soils were dry. Wet conditions apparently expand floodplain clays, closing macropores and cracks that act as conduits for groundwater recharge. Modelled groundwater flow paths were consistent with tritium dating and provided independent evidence that the clay layer does not prevent local recharge. Overall, all lines of evidence demonstrated that the coastal floodplain muds do not prevent the infiltration of rainwater into the underlying sand aquifer, and that local recharge across the muds was widespread. Therefore, assuming fine-grained floodplain soils prevent recharge and protect underlying aquifers from pollution may not be reasonable. Copyright © 2016 Elsevier B.V. All rights reserved.

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

Science.gov (United States)

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

2017-01-01

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

Ground-Water Flow Model for the Spokane Valley-Rathdrum Prairie Aquifer, Spokane County, Washington, and Bonner and Kootenai Counties, Idaho

Science.gov (United States)

Hsieh, Paul A.; Barber, Michael E.; Contor, Bryce A.; Hossain, Md. Akram; Johnson, Gary S.; Jones, Joseph L.; Wylie, Allan H.

2007-01-01

This report presents a computer model of ground-water flow in the Spokane Valley-Rathdrum Prairie (SVRP) aquifer in Spokane County, Washington, and Bonner and Kootenai Counties, Idaho. The aquifer is the sole source of drinking water for more than 500,000 residents in the area. In response to the concerns about the impacts of increased ground-water withdrawals resulting from recent and projected urban growth, a comprehensive study was initiated by the Idaho Department of Water Resources, the Washington Department of Ecology, and the U.S. Geological Survey to improve the understanding of ground-water flow in the aquifer and of the interaction between ground water and surface water. The ground-water flow model presented in this report is one component of this comprehensive study. The primary purpose of the model is to serve as a tool for analyzing aquifer inflows and outflows, simulating the effects of future changes in ground-water withdrawals from the aquifer, and evaluating aquifer management strategies. The scale of the model and the level of detail are intended for analysis of aquifer-wide water-supply issues. The SVRP aquifer model was developed by the Modeling Team formed within the comprehensive study. The Modeling Team consisted of staff and personnel working under contract with the Idaho Department of Water Resources, personnel working under contract with the Washington Department of Ecology, and staff of the U.S. Geological Survey. To arrive at a final model that has the endorsement of all team members, decisions on modeling approach, methodology, assumptions, and interpretations were reached by consensus. The ground-water flow model MODFLOW-2000 was used to simulate ground-water flow in the SVPR aquifer. The finite-difference model grid consists of 172 rows, 256 columns, and 3 layers. Ground-water flow was simulated from September 1990 through September 2005 using 181 stress periods of 1 month each. The areal extent of the model encompasses an area of

Study of the leakage between two aquifers in Hermosillo, Mexico, using environmental isotopes

International Nuclear Information System (INIS)

Payne, B.R.; Quijano, L.; Latorre, D.C.

1980-01-01

The Coast of Hermosillo is located in the Gulf of California, Mexico. It is a Quaternary alluvial plain of continental origin. Underlying these deposits is a layer of blue clay about 100m thick which imposes confinement to a deep aquifer in basaltic and pyroclastic rocks. Oxygen-18 and deuterium data support the occurrence of an upwardsleakage. The amount of the leakage was evaluated, on the basis of 14 C data, to a maximum of 20% of the water pumped by the irrigation wells in the upper aquifer. The stable isotope data also support the occurrence of sea-water intrusion by preferential channels in the south and in the area of Kino Bay. (author)

Hydrogeology - AQUIFER_SYSTEMS_UNCONSOLIDATED_IDNR_IN: Unconsolidated Aquifer Systems of Indiana (Indiana Department of Natural Resources, 1:48,000, Polygon Shapefile)

Data.gov (United States)

NSGIC State | GIS Inventory — AQUIFER_SYSTEMS_UNCONSOLIDATED_IDNR_IN is a polygon shapefile that shows unconsolidated aquifer systems of the state of Indiana at a scale of 1:48,000. The following...

Hydrogeology of the Umm Er Radhuma Aquifer (Arabian peninsula)

Science.gov (United States)

Dirks, Heiko; Al Ajmi, Hussain; Kienast, Peter; Rausch, Randolf

2018-03-01

The aim of this article is to enhance the understanding of the Umm Er Radhuma aquifer's genesis, and its hydraulic and hydrochemical development over time. This is a prerequisite for wise use of the fossil groundwater resources contained within. The Umm Er Radhuma is a karstified limestone aquifer, extending over 1.6 Mio. km2 in the eastern part of the Arabian Peninsula. Both epigene and hypogene karstification contributed to the genesis of what is today the most prolific aquifer in the region. Besides man-made abstractions, even the natural outflows are higher than the small recharge (natural storage depletion). The Umm Er Radhuma shows that large aquifers in arid regions are never in "steady state" (where inflows equal outflows), considering Quaternary climate history. The aquifer's adaption to climate changes (precipitation, sea level) can be traced even after thousands of years, and is slower than the climate changes themselves.

Simple method for quick estimation of aquifer hydrogeological parameters

Science.gov (United States)

Ma, C.; Li, Y. Y.

2017-08-01

Development of simple and accurate methods to determine the aquifer hydrogeological parameters was of importance for groundwater resources assessment and management. Aiming at the present issue of estimating aquifer parameters based on some data of the unsteady pumping test, a fitting function of Theis well function was proposed using fitting optimization method and then a unitary linear regression equation was established. The aquifer parameters could be obtained by solving coefficients of the regression equation. The application of the proposed method was illustrated, using two published data sets. By the error statistics and analysis on the pumping drawdown, it showed that the method proposed in this paper yielded quick and accurate estimates of the aquifer parameters. The proposed method could reliably identify the aquifer parameters from long distance observed drawdowns and early drawdowns. It was hoped that the proposed method in this paper would be helpful for practicing hydrogeologists and hydrologists.

Environmental effects of aquifer overexploitation: a case study in the highlands of Mexico.

Science.gov (United States)

Esteller, Maria Vicenta; Diaz-Delgado, Carlos

2002-02-01

There are several environmental processes occurring under aquifer overexploitation conditions. These processes include groundwater table decline, subsidence, attenuation and drying of springs, decrease of river flow, and increased pollution vulnerability, among others processes. Some of these effects have been observed on the Upper Basin of the Lerma River. The Lerma River begins in the SE of the Valley of Toluca at 2,600 m asl, in the wetland known as Lagoons of Almoloya del Río. This wetland is made up of a group of lagoons, which are an important aquatic system from an environmental point of view. The water inflow of this wetland is a discharge of springs, which occur between the fractured volcanic material of the mountain range and granular volcanic-continental deposits of the Valley of Toluca aquifer. The intensive exploitation of the Valley of Toluca aquifer to supply urban and industrial water to Mexico City and Toluca began in 1950 and is responsible for a steady decline of piezometric levels of 1-3.5 m/yr. Other effects of this exploitation--the drying of the wetland, the decrease of river flow and the land subsidence--caused serious ecological and social impacts. The authorities declared this aquifer as overexploited in order to reduce the exploitation and preserve the availability of water resources in this important region.

In situ treatment of arsenic contaminated groundwater by aquifer iron coating: Experimental study

Energy Technology Data Exchange (ETDEWEB)

Xie, Xianjun, E-mail: xjxie@cug.edu.cn [State Key Laboratory of Biogeology and Environmental Geology, School of Environmental Studies, China University of Geosciences, 430074 Wuhan (China); Wang, Yanxin, E-mail: yx.wang@cug.edu.cn [State Key Laboratory of Biogeology and Environmental Geology, School of Environmental Studies, China University of Geosciences, 430074 Wuhan (China); Pi, Kunfu [State Key Laboratory of Biogeology and Environmental Geology, School of Environmental Studies, China University of Geosciences, 430074 Wuhan (China); Liu, Chongxuan [State Key Laboratory of Biogeology and Environmental Geology, School of Environmental Studies, China University of Geosciences, 430074 Wuhan (China); Pacific Northwest National Laboratory, Richland, WA 99354 (United States); Li, Junxia; Liu, Yaqing; Wang, Zhiqiang; Duan, Mengyu [State Key Laboratory of Biogeology and Environmental Geology, School of Environmental Studies, China University of Geosciences, 430074 Wuhan (China)

2015-09-15

In situ arsenic removal from groundwater by an aquifer iron coating method has great potential to be a cost effective and simple groundwater remediation technology, especially in rural and remote areas where groundwater is used as the main water source for drinking. The in situ arsenic removal technology was first optimized by simulating arsenic removal in various quartz sand columns under anoxic conditions. The effectiveness was then evaluated in an actual high-arsenic groundwater environment. The arsenic removal mechanism by the coated iron oxide/hydroxide was investigated under different conditions using scanning electron microscopy (SEM)/X-ray absorption spectroscopy, electron probe microanalysis, and Fourier transformation infrared spectroscopy. Aquifer iron coating method was developed via a 4-step alternating injection of oxidant, iron salt and oxygen-free water. A continuous injection of 5.0 mmol/L FeSO{sub 4} and 2.5 mmol/L NaClO for 96 h can form a uniform goethite coating on the surface of quartz sand without causing clogging. At a flow rate of 7.2 mL/min of the injection reagents, arsenic (as Na{sub 2}HAsO{sub 4}) and tracer fluorescein sodium to pass through the iron-coated quartz sand column were approximately at 126 and 7 column pore volumes, respectively. The retardation factor of arsenic was 23.0, and the adsorption capacity was 0.11 mol As per mol Fe. In situ arsenic removal from groundwater in an aquifer was achieved by simultaneous injections of As(V) and Fe(II) reagents. Arsenic fixation resulted from a process of adsorption/co-precipitation with fine goethite particles by way of bidentate binuclear complexes. Therefore, the study results indicate that the high arsenic removal efficiency of the in situ aquifer iron coating technology likely resulted from the expanded specific surface area of the small goethite particles, which enhanced arsenic sorption capability and/or from co-precipitation of arsenic on the surface of goethite particles

In situ treatment of arsenic contaminated groundwater by aquifer iron coating: Experimental study

International Nuclear Information System (INIS)

Xie, Xianjun; Wang, Yanxin; Pi, Kunfu; Liu, Chongxuan; Li, Junxia; Liu, Yaqing; Wang, Zhiqiang; Duan, Mengyu

2015-01-01

In situ arsenic removal from groundwater by an aquifer iron coating method has great potential to be a cost effective and simple groundwater remediation technology, especially in rural and remote areas where groundwater is used as the main water source for drinking. The in situ arsenic removal technology was first optimized by simulating arsenic removal in various quartz sand columns under anoxic conditions. The effectiveness was then evaluated in an actual high-arsenic groundwater environment. The arsenic removal mechanism by the coated iron oxide/hydroxide was investigated under different conditions using scanning electron microscopy (SEM)/X-ray absorption spectroscopy, electron probe microanalysis, and Fourier transformation infrared spectroscopy. Aquifer iron coating method was developed via a 4-step alternating injection of oxidant, iron salt and oxygen-free water. A continuous injection of 5.0 mmol/L FeSO 4 and 2.5 mmol/L NaClO for 96 h can form a uniform goethite coating on the surface of quartz sand without causing clogging. At a flow rate of 7.2 mL/min of the injection reagents, arsenic (as Na 2 HAsO 4 ) and tracer fluorescein sodium to pass through the iron-coated quartz sand column were approximately at 126 and 7 column pore volumes, respectively. The retardation factor of arsenic was 23.0, and the adsorption capacity was 0.11 mol As per mol Fe. In situ arsenic removal from groundwater in an aquifer was achieved by simultaneous injections of As(V) and Fe(II) reagents. Arsenic fixation resulted from a process of adsorption/co-precipitation with fine goethite particles by way of bidentate binuclear complexes. Therefore, the study results indicate that the high arsenic removal efficiency of the in situ aquifer iron coating technology likely resulted from the expanded specific surface area of the small goethite particles, which enhanced arsenic sorption capability and/or from co-precipitation of arsenic on the surface of goethite particles. - Highlights: �

Testing alternative conceptual models of seawater intrusion in a coastal aquifer using computer simulation, southern California, USA

Science.gov (United States)

Nishikawa, Tracy

1997-01-01

Two alternative conceptual models of the physical processes controlling seawater intrusion in a coastal basin in California, USA, were tested to identify a likely principal pathway for seawater intrusion. The conceptual models were tested by using a two-dimensional, finite-element groundwater flow and transport model. This pathway was identified by the conceptual model that best replicated the historical data. The numerical model was applied in cross section to a submarine canyon that is a main avenue for seawater to enter the aquifer system underlying the study area. Both models are characterized by a heterogeneous, layered, water-bearing aquifer. However, the first model is characterized by flat-lying aquifer layers and by a high value of hydraulic conductivity in the basal aquifer layer, which is thought to be a principal conduit for seawater intrusion. The second model is characterized by offshore folding, which was modeled as a very nearshore outcrop, thereby providing a shorter path for seawater to intrude. General conclusions are that: 1) the aquifer system is best modeled as a flat, heterogeneous, layered system; 2) relatively thin basal layers with relatively high values of hydraulic conductivity are the principal pathways for seawater intrusion; and 3) continuous clay layers of low hydraulic conductivity play an important role in controlling the movement of seawater.

Geohydrology of the valley-fill aquifer in the Ramapo and Mahwah rivers area, Rockland County, New York

Science.gov (United States)

Moore, Richard Bridge; Cadwell, D.H.; Stelz, W.G.; Belli, J.L.

1982-01-01

This report is the eighth in a series of 11 map sets depicting geohydrologic conditions in selected aquifers in upstate New York. Geohydrologic data are compiled on six maps at 1:24,000 scale. Together, the maps provide a comprehensive overview of a major valley-fill aquifer in southeastern Rockland County. The maps include surficial geology, geologic sections, water-infiltration potential of soil zone, aquifer thickness, water-table elevations, well yields, and land use. The valley-fill deposits consists of alluvial silt and sand, glacial outwash (sand and gravel), ice-contact sand and gravel, till, and lacustrine silt and clay. The sand and gravel beds have relatively high permeabilities, whereas the till, silt, and clay deposits have relatively low permeabilities. Water-table conditions prevail in unconfined sand and gravel along the Ramapo River valley and much of the Mahwah River valley. Artesian conditions prevail in confined sand and gravel buried under silt and clay and till in parts of the Mahway valley. The aquifer is recharged throughout, where the land surface is most permeable and is greatest along the margin of the valley, where runoff from the hillsides is concentrated. The use of land overlying the aquifer is predominantly commercial, agricultural and residential, with lesser industrial uses. (USGS)

isotopic characteristics of aquifers in sinai

International Nuclear Information System (INIS)

Al-Gamal, S.A.

2004-01-01

the environmental isotopes data (expressed as δ 2 d and δ 18 O) of different aquifers in sinai were treated using correlation and regression techniques. whereas, rain water isotopic data were treated using empirical orthogonal functions (EOF) techniques. environmental isotopes for different aquifers expressed in terms of O-18 and H-2, were taken to represent the isotopic characteristics. regression equations using the highly correlated variables of δ 2 d and δ 18 O were constructed for each aquifer. the latitudinal variations (of rainwater in sinai and selected climatic stations east mediterranean ) versus rainwater isotopic compositions were analyzed using the normalized variables. it was found that the latitudinal variations of the rainwater isotopic compositions ( δ 2 D, δ 18 O), vapor pressure, and surface temperature occurred in parallel and decreased with latitude. in the east mediterranean, empirical linear relationship between altitude and δ 2 D has indicted that the rate of change of δ 2 D with height is comparable with the dry lapse rate in the atmosphere.The obtained regression equations of environmental isotopes data have impacted on different slopes and different constants expressing the non-homogeneity in the isotopic composition of rainwater recharging the aquifers of sinai , due to the presence of different air masses

Groundwater Flow Model of Göksu Delta Coastal Aquifer System

Science.gov (United States)

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

2016-04-01

the conceptual hydrogeological model of Göksu Delta coastal aquifer system, Göksu Delta is restricted by limestones from north and northwest and reaches up to 250 m in thickness in the southern part. Moreover, a combined aquifer system of confined and unconfined layers has been developed within the delta. The groundwater flow direction is towards south and southeast to the Mediterranean Sea. Data from this study were used to calibrate the flow model under steady-state and transient conditions by using MOFLOW. According to the calibrated model, alluvium aquifer is primarily recharged by limestone aquifer and partially by Göksu River. Discharge from the aquifer is generally towards the Mediterranean Sea and in part to Göksu River in the southern part of the delta. Transient calibration of the model for the year 2012 indicates that Göksu Delta groundwater system is extremely sensitive for groundwater exploitation for agricultural purposes.

Drought-sensitive aquifer settings in southeastern Pennsylvania

Science.gov (United States)

Zimmerman, Tammy M.; Risser, Dennis W.

2005-01-01

This report describes the results of a study conducted by the U.S. Geological Survey, in cooperation with the Pennsylvania Department of Conservation and Natural Resources, Bureau of Topographic and Geologic Survey, to determine drought-sensitive aquifer settings in southeastern Pennsylvania. Because all or parts of southeastern Pennsylvania have been in drought-warning or drought-emergency status during 6 of the past 10 years from 1994 through 2004, this information should aid well owners, drillers, and water-resource managers in guiding appropriate well construction and sustainable use of Pennsylvania's water resources. 'Drought-sensitive' aquifer settings are defined for this study as areas unable to supply adequate quantities of water to wells during drought. Using information from previous investigations and a knowledge of the hydrogeology and topography of the study area, drought-sensitive aquifer settings in southeastern Pennsylvania were hypothesized as being associated with two factors - a water-table decline (WTD) index and topographic setting. The WTD index is an estimate of the theoretical water-table decline at the ground-water divide for a hypothetical aquifer with idealized geometry. The index shows the magnitude of ground-water decline after cessation of recharge is a function of (1) distance from stream to divide, (2) ground-water recharge rate, (3) transmissivity, (4) specific yield, and (5) duration of the drought. WTD indices were developed for 39 aquifers that were subsequently grouped into categories of high, moderate, and low WTD index. Drought-sensitive settings determined from the hypothesized factors were compared to locations of wells known to have been affected (gone dry, replaced, or deepened) during recent droughts. Information collected from well owners, drillers, and public agencies identified 2,016 wells affected by drought during 1998-2002. Most of the available data on the location of drought-affected wells in the study area were

Hydrogeological impact of fault zones on a fractured carbonate aquifer, Semmering (Austria)

Science.gov (United States)

Mayaud, Cyril; Winkler, Gerfried; Reichl, Peter

2015-04-01

simulations were done under laminar flow conditions, an attempt allowing nonlinear flow with a new released package was implemented later. Preliminary results show that the implementation of the three faults zones with a much lower hydraulic conductivity compared to the aquifer is essential to reproduce properly both situations with and without pumping. This approves the high impact of fault zones on groundwater flow in fractured aquifer systems. Finally, this example shows that numerical modelling can help to reduce the uncertainties of conceptual models.

Optimal Aquifer Pumping Policy to Reduce Contaminant Concentration

Directory of Open Access Journals (Sweden)

Ali Abaei

2012-01-01

Full Text Available Different sources of ground water contamination lead to non-uniform distribution of contaminant concentration in the aquifer. If elimination or containment of pollution sources was not possible, the distribution of contaminant concentrations could be modified in order to eliminate peak concentrations using optimal water pumping discharge plan. In the present investigation Visual MODFLOW model was used to simulate the flow and transport in a hypothetic aquifer. Genetic Algorithm (GA also was applied to optimize the location and pumping flow rate of wells in order to reduce contaminants peak concentrations in aquifer.

Chemical and microbiological monitoring of a sole-source aquifer intended for artificial recharge, Nassau County, New York

Science.gov (United States)

Katz, Brian G.; Mallard, Gail E.

1980-01-01

In late 1980, approximately 4 million gallons per day of highly treated wastewater will be used to recharge the groundwater reservoir in central Nassau County through a system of 10 recharge basins and 5 shallow injection wells. To evaluate the impact of large-scale recharge with reclaimed water on groundwater quality, the U.S. Geological Survey has collected hydrologic and water-quality data from a 1-square-mile area around the recharge site to provide a basis for future comparison. Extensive chemical and microbiological analyses are being made on samples from 48 wells screened in the upper glacial (water-table) aquifer and the upper part of the underlying Magothy (public-supply) aquifer. Preliminary results indicate that water from the upper glacial aquifer contains significant concentrations of nitrate and low-molecular-weight chlorinated hydrocarbons and detectable concentrations of organochlorine insecticides and polychlorinated biphenyls. At present, no fecal contamination is evident in either aquifer in the area studied. In the few samples containing fecal indicator bacteria, the numbers were low. Nonpoint sources provide significant loads of organic and inorganic compounds; major sources include cesspool and septic-tank effluent, cesspool and septic-tank cleaners and other over-the-counter domestic organic solvents, fertilizers, insecticides for termite and other pest control, and stormwater runoff to recharge basins. The water-table aquifer is composed mainly of stratified, well-sorted sand and gravel and, as a result, is highly permeable. In the 1-square-mile area studied, some contaminants seem to have traveled 200 feet downward to the bottom of the water-table aquifer and into the upper part of the public-supply aquifer. (USGS)

Sedimentological analysis of a contaminated groundwater aquifer

International Nuclear Information System (INIS)

Towse, D.

1991-01-01

The use of sedimentological reservoir analysis techniques adapted from standard oilfield practice can improve the efficiency and reduce the costs of the evaluation of groundwater aquifers and the design of restoration programs. An evaluation/restoration program at a site in California drilled over 200 test wells in about 750 ac. All wells were logged lithologically and with wireline. The shallow aquifer is a complex braided alluvial floodplain deposit of Late Quaternary age. Analysis demonstrates depositional and erosional responses to periodic hinterland uplifts and to changing climatic conditions. Channel, overbank, lacustrine, and minor deltaic deposits can be recognized. The aquifer architecture has been interpreted to explain the movement of fuel and halogenated hydrocarbon solvents in the sediments and water. Routine engineering geology techniques and hydrologic tests were used to evaluate contamination and to design experimental restoration processes. As demonstrated here, sedimentological techniques show promise in reducing the costs and time required for this type of study. The abundant detailed data will be used in an attempt to develop a microcomputer-based expert system for rapid preliminary analyses of similar aquifers or reservoirs

Application of groundwater sustainability indicators to the Upper Pliocene aquifer in Ho Chi Minh city, Viet Nam

Science.gov (United States)

Ngo, T. M.; Lee, J.; Lee, H.; Woo, N. C.

2013-12-01

Groundwater plays an importance role for domestic, industrial, and agricultural uses in Ho Chi Minh city, Viet Nam. This study is objected to evaluate the sustainability of groundwater by using groundwater sustainability indicators (GWSIs) defined by UNESCO/IAEA/IAH Working Group on Groundwater Indicators at aquifer scale (the Upper Pliocene aquifer). There are four main indicators selected and one new indicator designed for the particular characteristic of Ho Chi Minh city which is under influence of by saline-water intrusion. The results indicated groundwater of the Upper Pliocene aquifer, the main groundwater supply source, is generally in the unsustainable state. The abstraction of groundwater, which was much greater than its capability, is probably causing the serious state of annual groundwater depletion and saline-water intrusion. The GWSIs, which expressed in such a simple way but scientifically-based and policy-relevant, proved its usefulness in evaluating the sustainability of groundwater at the aquifer scale in Ho Chi Minh city, and subsequently should be incorporated in water resource management practices.

Visualization of residual organic liquid trapped in aquifers

International Nuclear Information System (INIS)

Conrad, S.H.; Wilson, J.L.; Mason, W.R.; Peplinski, W.J.

1992-01-01

Organic liquids that are essentially immiscible with water migrate through the subsurface under the influence of capillary, viscous, and buoyancy forces. These liquids originate from the improper disposal of hazardous wastes, and the spills and leaks of petroleum hydrocarbons and solvents. The flow visualization experiments described in this study examined the migration of organic liquids through the saturated zone of aquifers, with a primary focus on the behavior of the residual organic liquid saturation, referring to that portion of the organic liquid that is trapped by capillary forces. Etched glass micromodels were used to visually observe dynamic multiphase displacement processes in pore networks. The resulting fluid distributions were photographed. Pore and blob casts were produced by a technique in which an organic liquid was solidified in place within a sand column at the conclusion of a displacement. The columns were sectioned and examined under optical and scanning electron microscopes. Photomicrographs of these sections show the morphology of the organic phase and its location within the sand matrix. The photographs from both experimental techniques reveal that in the saturated zone large amounts of residual organic liquid are trapped as isolated blobs of microscopic size. The size, shape, and spatial distribution of these blobs of residual organic liquid affect the dissolution of organic liquid into the water phase and the biotransformation of organic components. These processes are of concern for the prediction of pollution migration and the design of aquifer remediation schemes

Disposal of carbon dioxide in aquifers in the U.S.

Energy Technology Data Exchange (ETDEWEB)

Winter, E.M.; Bergman, P.D.

1995-11-01

Deep saline aquifers were investigated as potential disposal sites for CO{sub 2}. The capacity of deep aquifers for CO{sub 2} disposal in the U.S. is highly uncertain. A rough estimate, derived from global estimates, is 5,500 Gt of CO{sub 2}. Saline aquifers underlie the regions in the U.S. where most utility power plants are situated. Therefore, approximately 65 percent of CO{sub 2} from power plants could possibly be injected directly into deep saline aquifers below these plants, without the need for long pipelines.

The Tunisian Jurassic aquifer in the North African Sahara aquifer system: information derived from two-dimensional seismic reflection and well logs

Science.gov (United States)

Ben Lasmar, Rafika; Guellala, Rihab; Garrach, Mohamed; Mahroug, Ali; Sarsar Naouali, Benen; Inoubli, Mohamed Hédi

2017-12-01

Southern Tunisia is an arid area where socio-economic activities are dependent on groundwater resources. The presented study aims to better characterize the Jurassic aquifer based on geological and geophysical data, with a view to develop a rational exploitation program. Well logs are used to precisely determine the position and composition of the known Jurassic aquifer layers and to identify others able to produce good quality water. The logs show that limestones, sandstones and dolomites of the Krachoua, Techout and Foum Tataouine formations are the main Jurassic aquifers. Sixty-eight seismic-reflection sections are integrated within this study. The interpolation between the interpreted sections leads to the construction of isochronous isopach maps and geoseismic sections, and their analysis finds that compressive and extensive tectonic deformations have influenced the Jurassic aquifer geometry. The Hercynian orogeny phase manifestation is remarkable in that there are several stratigraphic gaps in the Jurassic sequence. The E-W, NW-SE, and NNW-SSE accidents, reactivated in normal faults since the Permian to Lower Cretaceous epochs, have generated the structures found in the Jurassic series, such as subsided and raised blocks. Their syn-sedimentary activity has controlled the thickness and facies of these series. The Cretaceous, Tortonian and Post-Villafranchian compressions are responsible for the Jurassic-deposits folding in some localities. The highlighted tectonic and sedimentary events have an important impact on the Jurassic aquifer function by favoring the Jurassic aquifer interconnections and their connections with the Triassic and Cretaceous permeable series.

Implementation of a 3d numerical model of a folded multilayer carbonate aquifer

Science.gov (United States)

Di Salvo, Cristina; Guyennon, Nicolas; Romano, Emanuele; Bruna Petrangeli, Anna; Preziosi, Elisabetta

2016-04-01

fully-3D (with aquitards simulated explicitly and transient flow represented by 3D governing equations). At first, steady state simulation were run under average seasonal recharge. To overcome dry-cell problems in the FULL-3D model, the Newton-Raphson formulation for MODFLOW-2005 was invoked. Steady state calibration was achieved mainly using annual average flow along four streambed's Nera River springs and average water level data available only in two observation wells. Results show that a FULL-3D zoned model was required to match the observed distribution of river base flow. The FULL-3D model was then run in transient conditions (1990-2013) by using monthly spatially distributed recharge estimated using the Thornthwaite-Mather method based on 60 years of climate data. The monitored flow of one spring, used for public water supply, was used as proxy data for reconstruct Nera River hydrogram; proxy-based hydrogram was used for calibration of storage coefficients and further model's parameters adjustment. Once calibrated, the model was run under different aquifer management scenario (i.e., pumping wells planned to be active for water supply); the related risk of depletion of spring discharge and groundwater-surface water interaction was evaluated.

Groundwater Withdrawals under Drought: Reconciling GRACE and Models in the United States High Plains Aquifer

Science.gov (United States)

Nie, W.; Zaitchik, B. F.; Kumar, S.; Rodell, M.

2017-12-01

Advanced Land Surface Models (LSM) offer a powerful tool for studying and monitoring hydrological variability. Highly managed systems, however, present a challenge for these models, which typically have simplified or incomplete representations of human water use, if the process is represented at all. GRACE, meanwhile, detects the total change in water storage, including change due to human activities, but does not resolve the source of these changes. Here we examine recent groundwater declines in the US High Plains Aquifer (HPA), a region that is heavily utilized for irrigation and that is also affected by episodic drought. To understand observed decline in groundwater (well observation) and terrestrial water storage (GRACE) during a recent multi-year drought, we modify the Noah-MP LSM to include a groundwater pumping irrigation scheme. To account for seasonal and interannual variability in active irrigated area we apply a monthly time-varying greenness vegetation fraction (GVF) dataset to the model. A set of five experiments were performed to study the impact of irrigation with groundwater withdrawal on the simulated hydrological cycle of the HPA and to assess the importance of time-varying GVF when simulating drought conditions. The results show that including the groundwater pumping irrigation scheme in Noah-MP improves model agreement with GRACE mascon solutions for TWS and well observations of groundwater anomaly in the southern HPA, including Texas and Kansas, and that accounting for time-varying GVF is important for model realism under drought. Results for the HPA in Nebraska are mixed, likely due to misrepresentation of the recharge process. This presentation will highlight the value of the GRACE constraint for model development, present estimates of the relative contribution of climate variability and irrigation to declining TWS in the HPA under drought, and identify opportunities to integrate GRACE-FO with models for water resource monitoring in heavily

Upper Basalt-Confined Aquifer System in the Southern Hanford Site

International Nuclear Information System (INIS)

Thorne, P.

1999-01-01

The 1990 DOE Tiger Team Finding GW/CF-202 found that the hydrogeologic regime at the Hanford Site was inadequately characterized. This finding also identified the need for completing a study of the confined aquifer in the central and southern portions of the Hanford Site. The southern portion of the site is of particular interest because hydraulic-head patterns in the upper basalt-confined aquifer system indicate that groundwater from the Hanford central plateau area, where contaminants have been found in the aquifer, flows southeast toward the southern site boundary. This results in a potential for offsite migration of contaminants through the upper basalt-confined aquifer system. Based on the review presented in this report, available hydrogeologic characterization information for the upper basalt-confined aquifer system in this area is considered adequate to close the action item. Recently drilled offsite wells have provided additional information on the structure of the aquifer system in and near the southern part of the Hanford Site. Information on hydraulic properties, hydrochemistry, hydraulic heads and flow directions for the upper basalt-confined aquifer system has been re-examined and compiled in recent reports including Spane and Raymond (1993), Spane and Vermeul ( 1994), and Spane and Webber (1995)

Sorption of activation products on London clay and Dungeness aquifer gravel

Energy Technology Data Exchange (ETDEWEB)

Baston, G.M.N.; Berry, J.A.; Littleboy, A.K.; Pilkington, N.J. (AEA Decommissioning and Radwaste, Harwell Lab. (United Kingdom))

1992-01-01

The sortpion of a series of activation-product radionuclides onto London clay and Dungeness aquifer gravel from the nuclear reactor sites at Bradwell and Dungeness, has been examined. Batch sorption and through-diffusion experiments with clay determined chlorine as the chloride ion to be effectively non-sorbing; calcium to be weakly sorbing, whereas cobalt, nickel, niobium and samarium were moderately to strongly sorbing and silver was strongly sorbing. Distribution ratios (R[sub D] values) for Nb, Sm and Ag were found to have a strong dependence on the liquid-solid separation technique employed. The presence of high concentrations of calcium hydroxide led to lower values of R[sub D] for radioactive Ca but higher R[sub D] values for Sm and Ag. The sorption of Ni showed no apparent dependence on groundwater composition at low levels of dissolved organic carbon (DOC). The values of R[sub D] for Co decreased as the DOC content was increased by addition of humic materials. Batch sorption studies with aquifer gravel demonstrated that Ca is weakly sorbing whereas Nb, Ag and Eu are moderately to strongly sorbing. R[sub D] values for Ca and for Ag under neutral pH conditions show little sensitivity to the liquid/solid separation technique used. However, R[sub D] values for Nb and Eu under neutral pH conditions and for Ag in alkaline solution (pH = 11 - 12) show a marked effect. The aquifer gravel was found to be highly inhomogeneous unlike the clay and sorption was greatest on samples with a high proportion of sand, reflecting the clay mineral content. (orig.).

Ground-water levels in aquifers used for residential supply, Campton Township, Kane County, Illinois

Science.gov (United States)

Kay, Robert T.; Kraske, Kurt A.

1996-01-01

The U.S. Geological Survey, in cooperation with the Campton Township Board of Trustees, measured water levels in the aquifers used for residential supply in Campton Township, Kane County, Illinois. Aquifers used for residential supply are the shallow and deep aquifers in the glacial drift, composed of unconsolidated sand and gravels; the Alexandrian-Maquoketa aquifer, composed of dolomite and shale of the Alexandrian Series and the Maquoketa Group; the Galena-Platteville aquifer, composed of dolomite of the Platteville and Galena Groups; and the Ancell aquifer, composed of sandstones of the Glenwood Formation and the St. Peter Sanstone. Water-level altitudes in the shallow drift aquifers generally follow surface topography. Analysis of water-level data does not clearly indicate overutilization of these aquifers. Water-level altitudes in the deep drift aquifers decrease from west to east. Comparison of historical depth to water measurements with current (1995) measurements indicates large decreases in water levels in some areas. The deep drift aquifers may be overutilized at these locations. Water-level altitudes in the Alexandrian-Maquoketa aquifer generally decrease from west to east. The potentiometric surface of the aquifer follows the bedrock-surface topography in some locations. Localized low water-level altitudes and large decreases in water levels indicate the Alexandrian-Maquoketa aquifer is overutilized in several areas. Water-level altitudes in the wells finished in the Galena- Platteville aquifer vary by more than 300 feet. Large decreases in water levels in wells finished in the Galena-Platteville aquifer indicate the Galena-Platteville and Alexandrian-Maquoketa aquifers are overutilized in the northern part of the township. Water-level altitudes in the wells finished in the Ancell aquifer are also highly variable. There is no indication that the Ancell aquifer is overutilized.

San Pedro River Aquifer Binational Report

Science.gov (United States)

Callegary, James B.; Minjárez Sosa, Ismael; Tapia Villaseñor, Elia María; dos Santos, Placido; Monreal Saavedra, Rogelio; Grijalva Noriega, Franciso Javier; Huth, A. K.; Gray, Floyd; Scott, C. A.; Megdal, Sharon; Oroz Ramos, L. A.; Rangel Medina, Miguel; Leenhouts, James M.

2016-01-01

The United States and Mexico share waters in a number of hydrological basins and aquifers that cross the international boundary. Both countries recognize that, in a region of scarce water resources and expanding populations, a greater scientific understanding of these aquifer systems would be beneficial. In light of this, the Mexican and U.S. Principal Engineers of the International Boundary and Water Commission (IBWC) signed the “Joint Report of the Principal Engineers Regarding the Joint Cooperative Process United States-Mexico for the Transboundary Aquifer Assessment Program" on August 19, 2009 (IBWC-CILA, 2009). This IBWC “Joint Report” serves as the framework for U.S.-Mexico coordination and dialogue to implement transboundary aquifer studies. The document clarifies several details about the program such as background, roles, responsibilities, funding, relevance of the international water treaties, and the use of information collected or compiled as part of the program. In the document, it was agreed by the parties involved, which included the IBWC, the Mexican National Water Commission (CONAGUA), the U.S. Geological Survey (USGS), and the Universities of Arizona and Sonora, to study two priority binational aquifers, one in the San Pedro River basin and the other in the Santa Cruz River basin. This report focuses on the Binational San Pedro Basin (BSPB). Reasons for the focus on and interest in this aquifer include the fact that it is shared by the two countries, that the San Pedro River has an elevated ecological value because of the riparian ecosystem that it sustains, and that water resources are needed to sustain the river, existing communities, and continued development. This study describes the aquifer’s characteristics in its binational context; however, most of the scientific work has been undertaken for many years by each country without full knowledge of the conditions on the other side of the border. The general objective of this study is to

Insights on surface-water/groundwater exchange in the upper Floridan aquifer, north-central Florida (USA), from streamflow data and numerical modeling

Science.gov (United States)

Sutton, James E.; Screaton, Elizabeth J.; Martin, Jonathan B.

2015-03-01

Surface-water/groundwater exchange impacts water quality and budgets. In karst aquifers, these exchanges also play an important role in dissolution. Five years of river discharge data were analyzed and a transient groundwater flow model was developed to evaluate large-scale temporal and spatial variations of exchange between an 80-km stretch of the Suwannee River in north-central Florida (USA) and the karstic upper Floridan aquifer. The one-layer transient groundwater flow model was calibrated using groundwater levels from 59 monitoring wells, and fluxes were compared to the exchange calculated from discharge data. Both the numerical modeling and the discharge analysis suggest that the Suwannee River loses water under both low- and high-stage conditions. River losses appear greatest at the inside of a large meander, and the former river water may continue across the meander within the aquifer rather than return to the river. In addition, the numerical model calibration reveals that aquifer transmissivity is elevated within this large meander, which is consistent with enhanced dissolution due to river losses. The results show the importance of temporal and spatial variations in head gradients to exchange between streams and karst aquifers and dissolution of the aquifers.

Identifying Stream/Aquifer Exchange by Temperature Gradient in a Guarani Aquifer System Outcrop Zone

Science.gov (United States)

Wendland, E.; Rosa, D. M. S.; Anache, J. A. A.; Lowry, C.; Lin, Y. F. F.

2017-12-01

Recharge of the Guarani Aquifer System (GAS) in South America is supposed to occur mainly in the outcrop zones, where the GAS appears as an unconfined aquifer (10% of the 1.2 Million km2 aquifer extension). Previous evaluations of recharge are based essentially on water balance estimates for the whole aquifer area or water table fluctuations in monitoring wells. To gain a more detailed understanding of the recharge mechanisms the present work aimed to study the stream aquifer interaction in a watershed (Ribeirão da Onça) at an outcrop zone. Two Parshall flumes were installed 1.3 km apart for discharge measurement in the stream. Along this distance an optic fiber cable was deployed to identify stretches with gaining and losing behavior. In order to estimate groundwater discharge in specific locations, 8 temperature sticks were set up along the stream reach to measure continuously the vertical temperature gradient. A temperature probe with 4 thermistors was also used to map the shallow streambed temperature gradient manually along the whole distance. The obtained results show a discharge difference of 250 m3/h between both flumes. Since the last significant rainfall (15 mm) in the watershed occurred 3 months ago, this value can be interpreted as the base flow contribution to the stream during the dry season. Given the temperature difference between groundwater ( 24oC) and surface water ( 17oC) the fiber-optic distributed temperature sensing (FO-DTS) allowed the identification of stretches with gaining behavior. Temperature gradients observed at the streambed varied between 0.67 and 14.33 oC/m. The study demonstrated that heat may be used as natural tracer even in tropical conditions, where the groundwater temperature is higher than the surface water temperature during the winter. The obtained results show that the discharge difference between both flumes can not be extrapolated without detailed analysis. Gaining and loosing stretches have to be identified on order

Estimating aquifer transmissivity from geo-electrical sounding ...

African Journals Online (AJOL)

Aquifer resistivity range from 4.26 ohm-m to 755.3 ohm-m with maximum thickness of 52.25m. A maximum 55.52m depth- tobasement was obtained in the study area. Based on the model obtained, aquifer Transmissivity was calculated and was used to delineate the study area into prospective low and high groundwater ...

Contribution to isotopic and chemical study of the aquifers in the area of Frecheirinha, State of Ceara, Brazil

International Nuclear Information System (INIS)

Siqueira, H.B. de; Santiago, M.M.F.

1982-01-01

The isotopic and chemical characteristics of the aquifers in the area of Frecheirinha (State of Ceara) have been analyzed. In a area of 3,000 scquare Kilometers three aquifers has been identified. Oxygen-18 measurements show that during the rainy season the piezometric level rises until reaching the surface. Thus the flow-water is a mixture of rainwater with stored under-groundwater. Chemical analysis shows all waters (except for samples 1, 2 and 3) are potable. (L.H.L.L.) [pt

Managed aquifer recharge: rediscovering nature as a leading edge technology.

Science.gov (United States)

Dillon, P; Toze, S; Page, D; Vanderzalm, J; Bekele, E; Sidhu, J; Rinck-Pfeiffer, S

2010-01-01

Use of Managed Aquifer Recharge (MAR) has rapidly increased in Australia, USA, and Europe in recent years as an efficient means of recycling stormwater or treated sewage effluent for non-potable and indirect potable reuse in urban and rural areas. Yet aquifers have been relied on knowingly for water storage and unwittingly for water treatment for millennia. Hence if 'leading edge' is defined as 'the foremost part of a trend; a vanguard', it would be misleading to claim managed aquifer recharge as a leading edge technology. However it has taken a significant investment in scientific research in recent years to demonstrate the effectiveness of aquifers as sustainable treatment systems to enable managed aquifer recharge to be recognised along side engineered treatment systems in water recycling. It is a 'cross-over' technology that is applicable to water and wastewater treatment and makes use of passive low energy processes to spectacularly reduce the energy requirements for water supply. It is robust within limits, has low cost, is suitable from village to city scale supplies, and offers as yet almost untapped opportunities for producing safe drinking water supplies where they do not yet exist. It will have an increasingly valued role in securing water supplies to sustain cities affected by climate change and population growth. However it is not a universal panacea and relies on the presence of suitable aquifers and sources of water together with effective governance to ensure human health and environment protection and water resources planning and management. This paper describes managed aquifer recharge, illustrates its use in Australia, outlining economics, guidelines and policies, and presents some of the knowledge about aquifer treatment processes that are revealing the latent value of aquifers as urban water infrastructure and provide a driver to improving our understanding of urban hydrogeology.

Decision Support System for Aquifer Recharge (AR) and Aquifer Storage and Recovery (ASR) Planning, Design, and Evaluation - Principles and Technical Basis

Science.gov (United States)

Aquifer recharge (AR) is a technical method being utilized to enhance groundwater resources through man-made replenishment means, such as infiltration basins and injections wells. Aquifer storage and recovery (ASR) furthers the AR techniques by withdrawal of stored groundwater at...

Seawater intrusion in karstic, coastal aquifers: Current challenges and future scenarios in the Taranto area (southern Italy).

Science.gov (United States)

De Filippis, Giovanna; Foglia, Laura; Giudici, Mauro; Mehl, Steffen; Margiotta, Stefano; Negri, Sergio Luigi

2016-12-15

Mediterranean areas are characterized by complex hydrogeological systems, where management of freshwater resources, mostly stored in karstic, coastal aquifers, is necessary and requires the application of numerical tools to detect and prevent deterioration of groundwater, mostly caused by overexploitation. In the Taranto area (southern Italy), the deep, karstic aquifer is the only source of freshwater and satisfies the main human activities. Preserving quantity and quality of this system through management policies is so necessary and such task can be addressed through modeling tools which take into account human impacts and the effects of climate changes. A variable-density flow model was developed with SEAWAT to depict the "current" status of the saltwater intrusion, namely the status simulated over an average hydrogeological year. Considering the goals of this analysis and the scale at which the model was built, the equivalent porous medium approach was adopted to represent the deep aquifer. The effects that different flow boundary conditions along the coast have on the transport model were assessed. Furthermore, salinity stratification occurs within a strip spreading between 4km and 7km from the coast in the deep aquifer. The model predicts a similar phenomenon for some submarine freshwater springs and modeling outcomes were positively compared with measurements found in the literature. Two scenarios were simulated to assess the effects of decreased rainfall and increased pumping on saline intrusion. Major differences in the concentration field with respect to the "current" status were found where the hydraulic conductivity of the deep aquifer is higher and such differences are higher when Dirichlet flow boundary conditions are assigned. Furthermore, the Dirichlet boundary condition along the coast for transport modeling influences the concentration field in different scenarios at shallow depths; as such, concentration values simulated under stressed conditions

Radial flow towards well in leaky unconfined aquifer

Science.gov (United States)

Mishra, P. K.; Kuhlman, K. L.

2012-12-01

An analytical solution is developed for three-dimensional flow towards a partially penetrating large- diameter well in an unconfined aquifer bounded below by a leaky aquitard of finite or semi-infinite extent. The analytical solution is derived using Laplace and Hankel transforms, then inverted numerically. Existing solutions for flow in leaky unconfined aquifers neglect the unsaturated zone following an assumption of instantaneous drainage due to Neuman. We extend the theory of leakage in unconfined aquifers by (1) including water flow and storage in the unsaturated zone above the water table, and (2) allowing the finite-diameter pumping well to partially penetrate the aquifer. The investigation of model-predicted results shows that aquitard leakage leads to significant departure from the unconfined solution without leakage. The investigation of dimensionless time-drawdown relationships shows that the aquitard drawdown also depends on unsaturated zone properties and the pumping-well wellbore storage effects.

Restoration of Wadi Aquifers by Artificial Recharge with Treated Waste Water

KAUST Repository

Missimer, Thomas M.; Drewes, Jö rg E.; Amy, Gary L.; Maliva,, Robert G.; Keller, Stephanie

2012-01-01

, such as damage to sensitive nearshore marine environments and creation of high-salinity interior surface water areas. An investigation of the hydrogeology of wadi aquifers in Saudi Arabia revealed that these aquifers can be used to develop aquifer recharge

Pollutant sources in an arsenic-affected multilayer aquifer in the Po Plain of Italy: Implications for drinking-water supply.

Science.gov (United States)

Rotiroti, Marco; McArthur, John; Fumagalli, Letizia; Stefania, Gennaro A; Sacchi, Elisa; Bonomi, Tullia

2017-02-01

In aquifers 160 to 260m deep that used for public water-supply in an area ~150km 2 around the town of Cremona, in the Po Plain of Northern Italy, concentrations of arsenic (As) are increasing with time in some wells. The increase is due to drawdown of As-polluted groundwater (As ≤144μg/L) from overlying aquifers at depths 65 to 150m deep in response to large-scale abstraction for public supply. The increase in As threatens drinking-water quality locally, and by inference does so across the entire Po Plain, where natural As-pollution of groundwater (As >10μg/L) is a basin-wide problem. Using new and legacy data for Cl/Br, δ 18 O/δ 2 H and other hydrochemical parameters with groundwater from 32 wells, 9 surface waters, a sewage outfall and rainwater, we show that the deep aquifer (160-260m below ground level), which is tapped widely for public water-supply, is partly recharged by seepage from overlying aquifers (65-150m below ground level). Groundwater quality in deep aquifers appears free of anthropogenic influences and typically water in some, not all, areas are affected by anthropogenic contamination and natural As-pollution (As >10μg/L). Outfalls from sewage-treatment plants and black water from septic tanks firstly affect surface waters, which then locally infiltrate shallow aquifers under high channel-stages. Wastewater permeating shallow aquifers carries with it NO 3 and SO 4 which suppress reduction of iron oxyhydroxides in the aquifer sediments and so suppress the natural release of As to groundwater. Copyright © 2016 Elsevier B.V. All rights reserved.

Hydraulic barrier against seawater intrusion in the main aquifer of Delta del Llobregat

International Nuclear Information System (INIS)

Ortuno Gobern, F.; Ninerola Pla, J. M.; Fraile, J.; Juarez, I.; Molinero Huguet, J.; Arcos, D.; Pitarch, J. L.

2009-01-01

The main aquifer of Delta del Llobregat (Barcelona, Spain) is affected by seawater intrusion from 1970. For stopping its advance, the Catalan Water Agency is carrying out the construction of a positive hydraulic barrier through the injection of water in 14 wells. This is the first project of these characteristic that it is carried out in Spain and pioneer in Europe. The barrier elevates the groundwater level of the aquifer near the coast and avoids that the seawater penetrates inland, using reclaimed water of Baix Llobregat WWTP with several treatments. The first phase brings already more than 2 years of functioning, with highly positive results since a substantial improvement of the quality of the groundwater has been observed. The second phase is at present under construction. (Author)

The hydrogeochemical and isotopic investigations of the two-layered Shiraz aquifer in the northwest of Maharlou saline lake, south of Iran

Science.gov (United States)

Tajabadi, Mehdi; Zare, Mohammad; Chitsazan, Manouchehr

2018-03-01

Maharlou saline lake is the outlet of Shiraz closed basin in southern Iran, surrounded by several disconnected alluvial fresh water aquifers. These aquifers in the west and northwest of the lake are recharged by karstic anticlines such as Kaftarak in the north and Barmshour in the south. Here groundwater salinity varies along the depth so that better quality water is located below brackish or saline waters. The aim of this study is to investigate the reason for the salinity anomaly and the origin of the fresher groundwater in lower depth. Hence, the change in groundwater salinity along depth has been investigated by means of a set of geoelectrical, hydrogeological, hydrogeochemical, and environmental isotopes data. The interpretation of geoelectrical profiles and hydrogeological data indicates that the aquifer in the southeast of Shiraz plain is a two-layer aquifer separated by a fine-grained (silt and clay) layer with an approximate thickness of 40 m at the depth of about 100-120 m. Hydrgeochemistry showed that the shallow aquifer is recharged by Kaftarak karstic anticline and is affected by the saline lake water. The lake water fraction varies in different parts from zero for shallow aquifer close to the karstic anticlines to ∼70 percent in the margin of the lake. The deep aquifer is protected from the intrusion of saline lake water due to the presence of the above-mentioned confining layer with lake water fraction of zero. The stable isotopes signatures also indicate that the 'fresh' groundwater belonging to the deep aquifer is not subject to severe evaporation or mixing which is typical of the karstic water of the area. It is concluded that the characteristics of the deep aquifer are similar to those of the karstic carbonate aquifer. This karstic aquifer is most probably the Barmshour carbonated anticline buried under the shallow aquifer in the southern part. It may also be the extension of the Kaftarak anticline in the northern part.

Predicting the denitrification capacity of sandy aquifers from shorter-term incubation experiments and sediment properties

Directory of Open Access Journals (Sweden)

W. Eschenbach

2013-02-01

Full Text Available Knowledge about the spatial variability of denitrification rates and the lifetime of denitrification in nitrate-contaminated aquifers is crucial to predict the development of groundwater quality. Therefore, regression models were derived to estimate the measured cumulative denitrification of aquifer sediments after one year of incubation from initial denitrification rates and several sediment parameters, namely total sulphur, total organic carbon, extractable sulphate, extractable dissolved organic carbon, hot water soluble organic carbon and potassium permanganate labile organic carbon.

For this purpose, we incubated aquifer material from two sandy Pleistocene aquifers in Northern Germany under anaerobic conditions in the laboratory using the ¹⁵N tracer technique. The measured amount of denitrification ranged from 0.19 to 56.2 mg N kg⁻¹ yr⁻¹. The laboratory incubations exhibited high differences between non-sulphidic and sulphidic aquifer material in both aquifers with respect to all investigated sediment parameters. Denitrification rates and the estimated lifetime of denitrification were higher in the sulphidic samples. For these samples, the cumulative denitrification measured during one year of incubation (D_cum(365 exhibited distinct linear regressions with the stock of reduced compounds in the investigated aquifer samples. D_cum(365 was predictable from sediment variables within a range of uncertainty of 0.5 to 2 (calculated D_cum(365/measured D_cum(365 for aquifer material with a D_cum(365 > 20 mg N kg⁻¹ yr⁻¹. Predictions were poor for samples with lower D_cum(365, such as samples from the NO₃⁻ bearing groundwater zone, which includes the non-sulphidic samples, from the upper part of both aquifers where denitrification is not sufficient to

Nitrate Contamination of Deep Aquifers in the Salinas Valley, California

Science.gov (United States)

Moran, J. E.; Esser, B. K.; Hillegonds, D. J.; Holtz, M.; Roberts, S. K.; Singleton, M. J.; Visser, A.; Kulongoski, J. T.; Belitz, K.

2011-12-01

The Salinas Valley, known as 'the salad bowl of the world', has been an agricultural center for more than 100 years. Irrigated row crops such as lettuce and strawberries dominate both land use and water use. Groundwater is the exclusive supply for both irrigation and drinking water. Some irrigation wells and most public water supply wells in the Salinas Valley are constructed to draw water from deep portions of the aquifer system, where contamination by nitrate is less likely than in the shallow portions of the aquifer system. However, a number of wells with top perforations greater than 75 m deep, screened below confining or semi-confining units, have nitrate concentrations greater than the Maximum Contaminant Limit (MCL) of 45 mg/L as NO3-. This study uses nitrate concentrations from several hundred irrigation, drinking water, and monitoring wells (Monterey County Water Resources Agency, 1997), along with tritium-helium groundwater ages acquired at Lawrence Livermore National Laboratory through the State of California Groundwater Monitoring and Assessment (GAMA) program (reported in Kulongoski et al., 2007 and in Moran et al., in press), to identify nitrate 'hot spots' in the deep aquifer and to examine possible modes of nitrate transport to the deep aquifer. In addition, observed apparent groundwater ages are compared with the results of transport simulations that use particle tracking and a stochastic-geostatistical framework to incorporate aquifer heterogeneity to determine the distribution of travel times from the water table to each well (Fogg et al., 1999). The combined evidence from nitrate, tritium, tritiogenic 3He, and radiogenic 4He concentrations, reveals complex recharge and flow to the capture zone of the deep drinking water wells. Widespread groundwater pumping for irrigation accelerates vertical groundwater flow such that high nitrate groundwater reaches some deep drinking water wells. Deeper portions of the wells often draw in water that recharged

Potential water supply of a small reservoir and alluvial aquifer system in southern Zimbabwe

NARCIS (Netherlands)

de Hamer, W.; Love, D.; Owen, R.; Booij, Martijn J.; Hoekstra, Arjen Ysbert

2008-01-01

Groundwater use by accessing alluvial aquifers of non-perennial rivers can be an important additional water resource in the semi-arid region of southern Zimbabwe. The research objective of the study was to calculate the potential water supply for the upper-Mnyabezi catchment under current conditions

Potential water supply of a small reservoir and alluvial aquifer system in southern Zimbabwe

NARCIS (Netherlands)

de Hamer, W.; Love, D.; Owen, R.; Booij, Martijn J.; Hoekstra, Arjen Ysbert

2007-01-01

Groundwater use by accessing alluvial aquifers of non‐perennial rivers can be an important additional water resource in the semi‐arid region of southern Zimbabwe. The research objective of the study was to calculate the potential water supply for the upper‐Mnyabezi catchment under current conditions

Managing A Lake/Aquifer System-Science, Policy, and the Public Interest

Science.gov (United States)

Shaver, R. B.

2009-12-01

Lake Isabel is a small (312 ha) natural lake located in central North Dakota in the glaciated Missouri Coteau. The average lake depth is about 1.8 m with a maximum depth of about 3.6 to 4.6 m. The lake overlies the Central Dakota aquifer complex which is comprised of three sand and gravel aquifer units that are either directly or indirectly (through leakage) hydraulically connected to the lake. The aquifer is a major water source for center pivot irrigation. During the 2001-2008 drought, lower lake levels reduced lake recreation, including leaving many boat docks unusable. Lake homeowners attribute lake level decline to irrigation pumping and believe that irrigation should be curtailed. There is no water right associated with Lake Isabel because there are no constructed works associated with the lake. Therefore, under North Dakota statute the lake cannot be protected as a prior (senior) appropriator. The lake does have standing under the public interest as defined by North Dakota statute. Evaluation of the public interest involves the integration of both science and policy. Is it in the best interest of the people of the state to prohibit ground water withdrawals for irrigation to protect the lake? This is a policy decision, not a scientific decision. The basis of the policy decision should include an economic analysis of the irrigated crops, fish, wildlife, recreation, and lake property. In addition, priority of use and lake level history should be considered. The issue can likely be resolved without scientific controversy arising from hydrologic system uncertainty. If the decision is to protect the lake at some level, the issue becomes “scientized” and the following questions need to be answered: 1) Does irrigation pumping effect changes in lake levels? 2) Is our level of scientific understanding sufficient to determine what volume of irrigation pumping will cause what amount of lake level change? 3) Given aquifer lag time response to changes in pumping and

Application of groundwater residence time tracers and broad screening for micro-organic contaminants in the Indo-Gangetic aquifer system

Science.gov (United States)

Lapworth, Dan; Das, Prerona; Mukherjee, Abhijit; Petersen, Jade; Gooddy, Daren; Krishan, Gopal

2017-04-01

Groundwater abstracted from aquifers underlying urban centres across India provide a vital source of domestic water. Abstraction from municipal and private supplies is considerable and growing rapidly with ever increasing demand for water from expanding urban populations. This trend is set to continue. The vulnerability of deeper aquifers (typically >100 m below ground) used for domestic water to contamination migration from often heavily contaminated shallow aquifer systems has not been studies in detail in India. This paper focusses on the occurrence of micro-organic contaminants within sedimentary aquifers beneath urban centres which are intensively pumped for drinking water and domestic use. New preliminary results from a detailed case study undertaken across Varanasi, a city with an estimated population of ca. 1.5 million in Uttar Pradesh. Micro -organic groundwater quality status and evolution with depth is investigated through selection of paired shallow and deep sites across the city. These results are considered within the context of paired groundwater residence time tracers within the top 150m within the sedimentary aquifer system. Groundwater emerging contaminant results are compared with surface water quality from the Ganges which is also used for drinking water supply. Broad screening for >800 micro-organic compounds was undertaken. Age dating tools were employed to constrain and inform a conceptual model of groundwater recharge and contaminant evolution within the sedimentary aquifer system.

Hydrologic analysis of data for the Lost Lake Aquifer Zone of the Steel Pond Aquifer at recovery well RWM-16

International Nuclear Information System (INIS)

Wells, D.G.; Cook, J.W.; Hiergesell, R.A.

1993-04-01

This report presents the results of an analysis of data obtained from a large-scale, multiple-well aquifer test of the sandy unit referred to as the Lost Lake Aquifer Zone of the Steed Pond Aquifer in an area just south of the A and M Areas. Pumping was conducted at recovery well RWM-16, which is located near the MSB-40 well cluster, approximately 4000 feet south of the M-Area Basin. RWM-16 is located in the lower left portion of Figure 1, which also illustrates the general relationship of the testing site to the A and M Areas and other monitor wells. The data generated from testing RWM-16 was used to calculate estimates of transmissivity and storage for the aquifer system within which RWM-16 is screened. These parameters are related to hydraulic conductivity and storativity of the aquifer system by the vertical thickness of the unit. The leakage coefficient for the overlying confining unit is also estimated. This information is needed to refine conceptual understanding of the groundwater flow system beneath the A and M Areas. The refined conceptual model will more adequately describe the pattern of groundwater flow, and will contribute to updating the open-quotes Zone of Captureclose quotes model that has been used in the initial phases of designing a groundwater remediation system in the A and M Areas

Characterising Bedrock Aquifer Systems in Korea Using Paired Water-Level Monitoring Data

Directory of Open Access Journals (Sweden)

Jae Min Lee

2017-06-01

Full Text Available This study focused on characterising aquifer systems based on water-level changes observed systematically at 159 paired groundwater monitoring wells throughout Korea. Using spectral analysis, principal component analysis (PCA, and cross-correlation analysis with linear regression, aquifer conditions were identified from the comparison of water-level changes in shallow alluvial and deep bedrock monitoring wells. The spectral analysis could identify the aquifer conditions (i.e., unconfined, semi-confined and confined of 58.5% of bedrock wells and 42.8% of alluvial wells: 93 and 68 wells out of 159 wells, respectively. Even among the bedrock wells, 50 wells (53.7% exhibited characteristics of the unconfined condition, implying significant vulnerability of the aquifer to contaminants from the land surface and shallow depths. It appears to be better approach for deep bedrock aquifers than shallow alluvial aquifers. However, significant portions of the water-level changes remained unclear for categorising aquifer conditions due to disturbances in data continuity. For different aquifer conditions, PCA could show typical pattern and factor scores of principal components. Principal component 1 due to wet-and-dry seasonal changes and water-level response time was dominant covering about 55% of total variances of each aquifer conditions, implying the usefulness of supplementary method of aquifer characterisation. Cross-correlation and time-lag analysis in the water-level responses to precipitations clearly show how the water levels in shallow and deep wells correspond in time scale. No significant differences in time-lags was found between shallow and deep wells. However, clear time-lags were found to be increasing from unconfined to confined conditions: from 1.47 to 2.75 days and from 1.78 to 2.75 days for both shallow alluvial and deep bedrock wells, respectively. In combination of various statistical methods, three types of water-level fluctuation

Quantitative groundwater modelling for a sustainable water resource exploitation in a Mediterranean alluvial aquifer

Science.gov (United States)

Laïssaoui, Mounir; Mesbah, Mohamed; Madani, Khodir; Kiniouar, Hocine

2018-05-01

To analyze the water budget under human influences in the Isser wadi alluvial aquifer in the northeast of Algeria, we built a mathematical model which can be used for better managing groundwater exploitation. A modular three-dimensional finite-difference groundwater flow model (MODFLOW) was used. The modelling system is largely based on physical laws and employs a numerical method of the finite difference to simulate water movement and fluxes in a horizontally discretized field. After calibration in steady-state, the model could reproduce the initial heads with a rather good precision. It enabled us to quantify the aquifer water balance terms and to obtain a conductivity zones distribution. The model also highlighted the relevant role of the Isser wadi which constitutes a drain of great importance for the aquifer, ensuring alone almost all outflows. The scenarios suggested in transient simulations showed that an increase in the pumping would only increase the lowering of the groundwater levels and disrupting natural balance of aquifer. However, it is clear that this situation depends primarily on the position of pumping wells in the plain as well as on the extracted volumes of water. As proven by the promising results of model, this physically based and distributed-parameter model is a valuable contribution to the ever-advancing technology of hydrological modelling and water resources assessment.

Migration rates of volatile organic compounds in an unconsolidated sand and gravel aquifer system

International Nuclear Information System (INIS)

Naidu, J.R.; Paquette, D.E.; Porcelli, D.R.

1993-01-01

The movement of volatile organic compounds (VOCs) in an aquifer is dictated by its solubility, attenuation characteristics, recharge volume, and ground-water movement (velocity and direction). At Brookhaven National Laboratory, past handling and disposal practices at the Hazardous Waste Management Facility and current landfill have resulted in the release of VOCs and the radioisotope tritium to the underlying upper glacial aquifer which characterized by unconsolidated sands and gravel. The rate of VOC migration from these source areas was examined using the following parameters: (1) distribution of VOCs and tritium; (2) tritium/helium ratios, which provide an estimate of the age of the water, and hence the rate of ground-water movement; (3) ground-water flow velocities within the upper glacial aquifer utilizing conductivity, porosity, and gradient data. Preliminary results indicate that whereas the comparison of the calculated ground-water flow gradient to tritium/helium age determinations are fairly consistent, application to VOC movement is inconclusive, and will require additional monitoring which would also focus on the vertical component as well

Determining shallow aquifer vulnerability by the DRASTIC model ...

Indian Academy of Sciences (India)

Shallow aquifer vulnerability has been assessed using GIS-based DRASTIC model by incorporating the major geological and hydrogeological factors that affect and control the groundwater contamination in a granitic terrain. It provides a relative indication of aquifer vulnerability to the contamination. Further, it has been ...

Tracers Detect Aquifer Contamination

National Research Council Canada - National Science Library

Enfield, Carl

1995-01-01

The EPA's National Laboratory (NRMRL) at Ada, OK, along with the University of Florida and the University of Texas, have developed a tracer procedure to detect the amount of contamination in aquifer formations...

VULNERABILITY AND RISK OF CONTAMINATION KARSTIC AQUIFERS

Directory of Open Access Journals (Sweden)

Yameli Aguilar

2013-08-01

Full Text Available Karstic systems occupy nearly 20% of the surface of the earth and are inhabited by numerous human communities. Karstic aquifers are the most exposed to pollution from human activities. Pollution of karstic aquifers is a severe environmental problem worldwide.  In order to face the vulnerability of karstic aquifers to pollution, researchers have created a diversity of study approaches and models, each one having their own strengths and weaknesses depending on the discipline from which they were originated, thus requiring a thorough discussion within the required multidisciplinary character. The objective of this article was to analyze the theoretical and methodological approaches applied to the pollution of karstic aquifers. The European hydrogeological, land evaluation, hydropedological and a geographic approach were analyzed. The relevance of a geomorphological analysis as a cartographic basis for the analysis of vulnerability and risks were emphasized. From the analysis of models, approaches and methodologies discussed the following recommendation is made: to form an interdisciplinary work team, to elaborate a conceptual model according to the site and the working scale and to e, apply and validate the model.

Geohydrology of the stratified-drift aquifer system in the lower Sixmile Creek and Willseyville Creek trough, Tompkins County, New York

Science.gov (United States)

Miller, Todd S.; Karig, Daniel E.

2010-01-01

retreats of the ice in the study area resulted in several sequences of various types of glacial deposits. A large moraine (Valley Heads Moraine) dominates the southern part of the study area, a large delta dominates the central part, and ground moraine (mostly till) dominates the northern part. Glacial sediments in the center of the lower Sixmile Creek and Willseyville Creek trough typically range from 150 to 200 ft but can be greater than 300 ft in some places. Where the sediments are composed of sand and gravel they form aquifers. In most parts of the lower Sixmile Creek and Willseyville Creek trough, there is an upper and a basal confined aquifer. However, underlying the central parts of the Brooktondale delta, there are as many as four confined aquifers, whereas in the northern part of the study area, only one extensive confined aquifer is present. The major sources of recharge to these confined aquifers are (1) direct infiltration of precipitation where confined aquifers crop out at land surface (mostly along the western trough wall in the southern and central parts of the study area and, to a lesser degree, along the eastern trough wall); (2) unchanneled surface and subsurface runoff from adjacent upland areas that seeps into the aquifer along the western trough walls; (3) subsurface flow from underlying till or bedrock at the lateral contacts at trough walls; (4) adjacent fine-grained stratified drift, especially when the aquifer is pumped; and (5) discharge from bedrock at the bottom and sides of the trough. In the central part of the study area, the surficial coarse-grained sediments (sand and gravel) comprise a delta near Brooktondale and form a small unconfined aquifer (0.3 square mile). Although much of the upper part of the delta has been removed by several aggregate mining operations, sufficient amounts of sand and gravel remain in most places to form a thin unconfined aquifer. The major sources of recharge to the unconfined aquifer are (1)

Study of variation in groundwater quality in a coastal aquifer in north-eastern Tunisia using multivariate factor analysis

KAUST Repository

Charfi, Sihem; Zouari, Kamel; Feki, Saber; Mami, Ezeddine

2013-01-01

This work focuses on the Grombalia aquifer which constitutes the main water resource in Northeast Tunisia, Cap Bon Peninsula. The recharge of this aquifer is ensured mainly by direct infiltration of rainwater through permeable layers. Under semi-arid climatic conditions and increasing water demand for irrigation, about 80% of the Grombalia aquifer system shows different vulnerabilities to anthropogenic activities. The total dissolved solids values range from 0.75 to 5.6g/l.Isotopic characterization with stable isotopes (δ2H and δ18O) of Grombalia aquifer system identified geochemistry processes that control water chemistry. In addition, the multivariate statistical technique (Principal Component Analysis) was used to identify the origin, the recharge mode and geochemical processes controlling groundwater quality. The principal reactions responsible for the hydrochemical evolution in the Grombalia groundwater fall into three categories: (1) denitrification process; (2) dissolution of salts; and (3) irrigation return flow process. Tritium data in groundwater from the study area suggest the existence of pre1950 and post1960 recharge. © 2012 Elsevier Ltd and INQUA.

Study of variation in groundwater quality in a coastal aquifer in north-eastern Tunisia using multivariate factor analysis

KAUST Repository

Charfi, Sihem

2013-07-01

This work focuses on the Grombalia aquifer which constitutes the main water resource in Northeast Tunisia, Cap Bon Peninsula. The recharge of this aquifer is ensured mainly by direct infiltration of rainwater through permeable layers. Under semi-arid climatic conditions and increasing water demand for irrigation, about 80% of the Grombalia aquifer system shows different vulnerabilities to anthropogenic activities. The total dissolved solids values range from 0.75 to 5.6g/l.Isotopic characterization with stable isotopes (δ2H and δ18O) of Grombalia aquifer system identified geochemistry processes that control water chemistry. In addition, the multivariate statistical technique (Principal Component Analysis) was used to identify the origin, the recharge mode and geochemical processes controlling groundwater quality. The principal reactions responsible for the hydrochemical evolution in the Grombalia groundwater fall into three categories: (1) denitrification process; (2) dissolution of salts; and (3) irrigation return flow process. Tritium data in groundwater from the study area suggest the existence of pre1950 and post1960 recharge. © 2012 Elsevier Ltd and INQUA.

FEWA: a Finite Element model of Water flow through Aquifers

International Nuclear Information System (INIS)

Yeh, G.T.; Huff, D.D.

1983-11-01

This report documents the implementation and demonstration of a Finite Element model of Water flow through Aquifers (FEWA). The particular features of FEWA are its versatility and flexibility to deal with as many real-world problems as possible. Point as well as distributed sources/sinks are included to represent recharges/pumpings and rainfall infiltrations. All sources/sinks can be transient or steady state. Prescribed hydraulic head on the Dirichlet boundaries and fluxes on Neumann or Cauchy boundaries can be time-dependent or constant. Source/sink strength over each element and node, hydraulic head at each Dirichlet boundary node, and flux at each boundary segment can vary independently of each other. Either completely confined or completely unconfined aquifers, or partially confined and partially unconfined aquifers can be dealt with effectively. Discretization of a compound region with very irregular curved boundaries is made easy by including both quadrilateral and triangular elements in the formulation. Large-field problems can be solved efficiently by including a pointwise iterative solution strategy as an optional alternative to the direct elimination solution method for the matrix equation approximating the partial differential equation of groundwater flow. FEWA also includes transient flow through confining leaky aquifers lying above and/or below the aquifer of interest. The model is verified against three simple cases to which analytical solutions are available. It is then demonstrated by two examples of how the model can be applied to heterogeneous and anisotropic aquifers with transient boundary conditions, time-dependent sources/sinks, and confining aquitards for a confined aquifer of variable thickness and for a free surface problem in an unconfined aquifer, respectively. 20 references, 25 figures, 8 tables

FEWA: a Finite Element model of Water flow through Aquifers

Energy Technology Data Exchange (ETDEWEB)

Yeh, G.T.; Huff, D.D.

1983-11-01

This report documents the implementation and demonstration of a Finite Element model of Water flow through Aquifers (FEWA). The particular features of FEWA are its versatility and flexibility to deal with as many real-world problems as possible. Point as well as distributed sources/sinks are included to represent recharges/pumpings and rainfall infiltrations. All sources/sinks can be transient or steady state. Prescribed hydraulic head on the Dirichlet boundaries and fluxes on Neumann or Cauchy boundaries can be time-dependent or constant. Source/sink strength over each element and node, hydraulic head at each Dirichlet boundary node, and flux at each boundary segment can vary independently of each other. Either completely confined or completely unconfined aquifers, or partially confined and partially unconfined aquifers can be dealt with effectively. Discretization of a compound region with very irregular curved boundaries is made easy by including both quadrilateral and triangular elements in the formulation. Large-field problems can be solved efficiently by including a pointwise iterative solution strategy as an optional alternative to the direct elimination solution method for the matrix equation approximating the partial differential equation of groundwater flow. FEWA also includes transient flow through confining leaky aquifers lying above and/or below the aquifer of interest. The model is verified against three simple cases to which analytical solutions are available. It is then demonstrated by two examples of how the model can be applied to heterogeneous and anisotropic aquifers with transient boundary conditions, time-dependent sources/sinks, and confining aquitards for a confined aquifer of variable thickness and for a free surface problem in an unconfined aquifer, respectively. 20 references, 25 figures, 8 tables.

The quality of our Nation's waters: water quality in the Upper Floridan aquifer and overlying surficial aquifers, southeastern United States, 1993-2010

Science.gov (United States)

Berndt, Marian P.; Katz, Brian G.; Kingsbury, James A.; Crandall, Christy A.

2015-01-01

About 10 million people rely on groundwater from the Upper Floridan and surficial aquifers for drinking water. The Upper Floridan aquifer also is of primary importance to the region as a source of water for irrigation and as a source of crystal clear water that discharges to springs and streams providing recreational and tourist destinations and unique aquatic habitats. The reliance of the region on the Upper Floridan aquifer for drinking water and for the tourism and agricultural economies highlights the importance of long-term management to sustain the availability and quality of these resources.

The contribution of environmental isotopes to studies of large aquifers in Morocco

International Nuclear Information System (INIS)

Kabbaj, A.; Zeryouhi, I.; Carlier, Ph.

1979-01-01

The geochemistry of environmental isotopes has been used for the study of various aquifers in Morocco, some of which are large, such as the Charf el Akab in the Tangiers area, the Oum er Rbia basin and the Turonian aquifer of the Tadla, the free groundwater of the Quaternary lacustrine limestones of the Sais Plain and the Lias limestone aquifer. These isotope studies take hydrogeochemical data into account and have made it possible to determine the conditions of recharge of the aquifers, to distinguish waters of different origin from the Atlas Mountains or from the Phosphate Plateau in the Tadla Basin and the Sais plain, to estimate the recharge of one aquifer by another - for example groundwater of the Lias limestones passing via the folds of the Sais Plain into the lacustrine limestone aquifer - and to test the homogeneity or heterogeneity of these aquifers and their tightness (e.g. the Turonian aquifer of the Tadla and the special case of the Charf el Akab in relation to the marine environment). Altogether, these results made it possible to test the value of the techniques used and to specify the general conditions in which they can profitably be used. (author)

Both Phosphorus Fertilizers and Indigenous Bacteria Enhance Arsenic Release into Groundwater in Arsenic-Contaminated Aquifers.

Science.gov (United States)

Lin, Tzu-Yu; Wei, Chia-Cheng; Huang, Chi-Wei; Chang, Chun-Han; Hsu, Fu-Lan; Liao, Vivian Hsiu-Chuan

2016-03-23

Arsenic (As) is a human carcinogen, and arsenic contamination in groundwater is a worldwide public health concern. Arsenic-affected areas are found in many places but are reported mostly in agricultural farmlands, yet the interaction of fertilizers, microorganisms, and arsenic mobilization in arsenic-contaminated aquifers remains uncharacterized. This study investigates the effects of fertilizers and bacteria on the mobilization of arsenic in two arsenic-contaminated aquifers. We performed microcosm experiments using arsenic-contaminated sediments and amended with inorganic nitrogenous or phosphorus fertilizers for 1 and 4 months under aerobic and anaerobic conditions. The results show that microcosms amended with 100 mg/L phosphorus fertilizers (dipotassium phosphate), but not nitrogenous fertilizers (ammonium sulfate), significantly increase aqueous As(III) release in arsenic-contaminated sediments under anaerobic condition. We also show that concentrations of iron, manganese, potassium, sodium, calcium, and magnesium are increased in the aqueous phase and that the addition of dipotassium phosphate causes a further increase in aqueous iron, potassium, and sodium, suggesting that multiple metal elements may take part in the arsenic release process. Furthermore, microbial analysis indicates that the dominant microbial phylum is shifted from α-proteobacteria to β- and γ-proteobacteria when the As(III) is increased and phosphate is added in the aquifer. Our results provide evidence that both phosphorus fertilizers and microorganisms can mediate the release of arsenic to groundwater in arsenic-contaminated sediments under anaerobic condition. Our study suggests that agricultural activity such as the use of fertilizers and monitoring phosphate concentration in groundwater should be taken into consideration for the management of arsenic in groundwater.

Managing a Common Pool Resource: Real Time Decision-Making in a Groundwater Aquifer

Science.gov (United States)

Sahu, R.; McLaughlin, D.

2017-12-01

In a Common Pool Resource (CPR) such as a groundwater aquifer, multiple landowners (agents) are competing for a limited resource of water. Landowners pump out the water to grow their own crops. Such problems can be posed as differential games, with agents all trying to control the behavior of the shared dynamic system. Each agent aims to maximize his/her own personal objective like agriculture yield, being aware that the action of every other agent collectively influences the behavior of the shared aquifer. The agents therefore choose a subgame perfect Nash equilibrium strategy that derives an optimal action for each agent based on the current state of the aquifer and assumes perfect information of every other agents' objective function. Furthermore, using an Iterated Best Response approach and interpolating techniques, an optimal pumping strategy can be computed for a more-realistic description of the groundwater model under certain assumptions. The numerical implementation of dynamic optimization techniques for a relevant description of the physical system yields results qualitatively different from the previous solutions obtained from simple abstractions.This work aims to bridge the gap between extensive modeling approaches in hydrology and competitive solution strategies in differential game theory.

The University of Minnesota aquifer thermal energy storage (ATES) field test facility -- system description, aquifer characterization, and results of short-term test cycles

Energy Technology Data Exchange (ETDEWEB)

Walton, M.; Hoyer, M.C.; Eisenreich, S.J.; Holm, N.L.; Holm, T.R.; Kanivetsky, R.; Jirsa, M.A.; Lee, H.C.; Lauer, J.L.; Miller, R.T.; Norton, J.L.; Runke, H. (Minnesota Geological Survey, St. Paul, MN (United States))

1991-06-01

Phase 1 of the Aquifer Thermal Energy Storage (ATES) Project at the University of Minnesota was to test the feasibility, and model, the ATES concept at temperatures above 100{degrees}C using a confined aquifer for the storage and recovery of hot water. Phase 1 included design, construction, and operation of a 5-MW thermal input/output field test facility (FTF) for four short-term ATES cycles (8 days each of heat injection, storage, and heat recover). Phase 1 was conducted from May 1980 to December 1983. This report describes the FTF, the Franconia-Ironton-Galesville (FIG) aquifer used for the test, and the four short-term ATES cycles. Heat recovery; operational experience; and thermal, chemical, hydrologic, and geologic effects are all included. The FTF consists of monitoring wells and the source and storage well doublet completed in the FIG aquifer with heat exchangers and a fixed-bed precipitator between the wells of the doublet. The FIG aquifer is highly layered and a really anisotropic. The upper Franconia and Ironton-Galesville parts of the aquifer, those parts screened, have hydraulic conductivities of {approximately}0.6 and {approximately}1.0 m/d, respectively. Primary ions in the ambient ground water are calcium and magnesium bicarbonate. Ambient temperature FIG ground water is saturated with respect to calcium/magnesium bicarbonate. Heating the ground water caused most of the dissolved calcium to precipitate out as calcium carbonate in the heat exchanger and precipitator. Silica, calcium, and magnesium were significantly higher in recovered water than in injected water, suggesting dissolution of some constituents of the aquifer during the cycles. Further work on the ground water chemistry is required to understand water-rock interactions.

Integrated subsurface water solutions for coastal environments through integrated pump&treat and aquifer storage and recovery (ASR) schemes

Science.gov (United States)

Perdikaki, Martha; Kallioras, Andreas; Christoforidis, Christophoros; Iossifidis, Dimitris; Zafeiropoulos, Anastasios; Dimitriadis, Klisthenis; Makropoulos, Christos; Raat, Klaasjan; van den Berg, Gerard

2016-04-01

Coastal wetlands in semi-arid regions, as in Circum-Mediterranean, are considered important ecosystems that provide valuable services to human population and the environment, such as: flood protection, erosion control, wildlife habitat, water quality, recreation and carbon sequestration. Un-managed surface and groundwater exploitation in these areas usually leads to deterioration of such sensitive ecosystems by means of water resources degradation and/or increased salinity. Groundwater usually plays a vital role for the sustainability of these hydrological systems, as the underlying aquifers operate as regulators for both quantity and quality of their waters. Multi-layer and multi-objective Managed Aquifer Recharge (MAR) systems can be proved effective groundwater engineered solutions for the restoration of deteriorated coastal wetlands in semi- and arid regions. The plain of Marathon is a typical Mediterranean environment that hosts a naturally occurring -and today degraded- coastal wetland with the characteristics of a distinct ecosystem linked to a typical coastal hydrogeological system of a semi-arid region; and therefore can serve as a model for similar systems world-wide. The geo-hydrological setting of the area involves a multi-layer aquifer system consisting of (i) an upper un-consolidated formation of depositional unit dominated mostly by fluvial sediments and (ii) the surrounding and underlying karstified marbles; both being linked to the investigated wetland and also subjected to seawater encroachment. A smart engineered MAR system via an optimised Pump & Treat system integrated with an Aquifer Storage and Recovery (ASR) scheme in this area would include the abstraction of brackish groundwater from the deeper karst aquifer at a location close to the shoreline and direct treatment with Reverse Osmosis (RO). for desalination. Two-fold re-use scheme of the purified effluent can then be engineered for (i) the restoration of the coastal wetland; and (ii

Unconsolidated Aquifers in Tompkins County, New York

Science.gov (United States)

Miller, Todd S.

2000-01-01

Unconsolidated aquifers consisting of saturated sand and gravel are capable of supplying large quantities of good-quality water to wells in Tompkins County, but little published geohydrologic inform ation on such aquifers is available. In 1986, the U.S.Geological Survey (USGS) began collecting geohydrologic information and well data to construct an aquifer map showing the extent of unconsolidated aquifers in Tompkins county. Data sources included (1) water-well drillers. logs; (2) highway and other construction test-boring logs; (3) well data gathered by the Tompkins County Department of Health, (4) test-well logs from geohydrologic consultants that conducted projects for site-specific studies, and (5) well data that had been collected during past investigations by the USGS and entered into the National Water Information System (NWIS) database. In 1999, the USGS, in cooperation with the Tompkins County Department of Planning, compiled these data to construct this map. More than 600 well records were entered into the NWIS database in 1999 to supplement the 350 well records already in the database; this provided a total of 950 well records. The data were digitized and imported into a geographic information system (GIS) coverage so that well locations could be plotted on a map, and well data could be tabulated in a digital data base through ARC/INFO software. Data on the surficial geology were used with geohydrologic data from well records and previous studies to delineate the extent of aquifers on this map. This map depicts (1) the extent of unconsolidated aquifers in Tompkins County, and (2) locations of wells whose records were entered into the USGS NWIS database and made into a GIS digital coverage. The hydrologic information presented here is generalized and is not intended for detailed site evaluations. Precise locations of geohydrologic-unit boundaries, and a description of the hydrologic conditions within the units, would require additional detailed, site

Effect of Short-Circuit Pathways on Water Quality in Selected Confined Aquifers (Invited)

Science.gov (United States)

McMahon, P. B.

2010-12-01

Confined aquifers in the United States generally contain fewer anthropogenic contaminants than unconfined aquifers because confined aquifers often contain water recharged prior to substantial human development and redox conditions are more reducing, which favors degradation of common contaminants like nitrate and chlorinated solvents. Groundwater in a confined part of the High Plains aquifer near York, Nebraska had an adjusted radiocarbon age of about 2,000 years, and groundwater in a confined part of the Floridan aquifer near Tampa, Florida had apparent ages greater than 60 years on the basis of tritium measurements. Yet compounds introduced more recently into the environment (anthropogenic nitrate and volatile organic compounds) were detected in selected public-supply wells completed in both aquifers. Depth-dependent measurements of flow and chemistry in the pumping supply wells, groundwater age dating, numerical modeling of groundwater flow, and other monitoring data indicated that the confined aquifers sampled by the supply wells were connected to contaminated unconfined aquifers by short-circuit pathways. In the High Plains aquifer, the primary pathways appeared to be inactive irrigation wells screened in both the unconfined and confined aquifers. In the Floridan aquifer, the primary pathways were karst sinkholes and conduits. Heavy pumping in both confined systems exacerbated the problem by reducing the potentiometric surface and increasing groundwater velocities, thus enhancing downward gradients and reducing reaction times for processes like denitrification. From a broader perspective, several confined aquifers in the U.S. have experienced large declines in their potentiometric surfaces because of groundwater pumping and this could increase the potential for contamination in those aquifers, particularly where short-circuit pathways connect them to shallower, contaminated sources of water, such as was observed in York and Tampa.

Simulation of seawater intrusion in coastal aquifers: Some typical ...

Indian Academy of Sciences (India)

Springer Verlag Heidelberg #4 2048 1996 Dec 15 10:16:45

Seawater intrusion; coastal aquifers; density-dependent flow and ... The seawater intrusion mechanism in coastal aquifers generally causes the occurrence of ... (4) The dynamic viscosity of the fluid does not change with respect to salinity and.

Solute concentration at a well in non-Gaussian aquifers under constant and time-varying pumping schedule

Science.gov (United States)

Libera, Arianna; de Barros, Felipe P. J.; Riva, Monica; Guadagnini, Alberto

2017-10-01

Our study is keyed to the analysis of the interplay between engineering factors (i.e., transient pumping rates versus less realistic but commonly analyzed uniform extraction rates) and the heterogeneous structure of the aquifer (as expressed by the probability distribution characterizing transmissivity) on contaminant transport. We explore the joint influence of diverse (a) groundwater pumping schedules (constant and variable in time) and (b) representations of the stochastic heterogeneous transmissivity (T) field on temporal histories of solute concentrations observed at an extraction well. The stochastic nature of T is rendered by modeling its natural logarithm, Y = ln T, through a typical Gaussian representation and the recently introduced Generalized sub-Gaussian (GSG) model. The latter has the unique property to embed scale-dependent non-Gaussian features of the main statistics of Y and its (spatial) increments, which have been documented in a variety of studies. We rely on numerical Monte Carlo simulations and compute the temporal evolution at the well of low order moments of the solute concentration (C), as well as statistics of the peak concentration (Cp), identified as the environmental performance metric of interest in this study. We show that the pumping schedule strongly affects the pattern of the temporal evolution of the first two statistical moments of C, regardless the nature (Gaussian or non-Gaussian) of the underlying Y field, whereas the latter quantitatively influences their magnitude. Our results show that uncertainty associated with C and Cp estimates is larger when operating under a transient extraction scheme than under the action of a uniform withdrawal schedule. The probability density function (PDF) of Cp displays a long positive tail in the presence of time-varying pumping schedule. All these aspects are magnified in the presence of non-Gaussian Y fields. Additionally, the PDF of Cp displays a bimodal shape for all types of pumping

Microcosm studies on iron and arsenic mobilization from aquifer sediments under different conditions of microbial activity and carbon source

Science.gov (United States)

Duan, Mengyu; Xie, Zuoming; Wang, Yanxin; Xie, Xianjun

2009-05-01

Microcosm experiments were conducted to understand the mechanism of microbially mediated mobilization of Fe and As from high arsenic aquifer sediments. Arsenic-resistant strains isolated from aquifer sediments of a borehole specifically drilled for this study at Datong basin were used as inoculated strains, and glucose and sodium acetate as carbon sources for the experiments. In abiotic control experiments, the maximum concentrations of Fe and As were only 0.47 mg/L and 0.9 μg/L, respectively. By contrast, the maximum contents of Fe and As in anaerobic microcosm experiments were much higher (up to 1.82 mg/L and 12.91 μg/L, respectively), indicating the crucial roles of microbial activities in Fe and As mobilization. The observed difference in Fe and As release with different carbon sources may be related to the difference in growth pattern and composition of microbial communities that develop in response to the type of carbon sources.

Simulated effects of groundwater withdrawals from the Kirkwood-Cohansey aquifer system and Piney Point aquifer, Maurice and Cohansey River Basins, Cumberland County and vicinity, New Jersey

Science.gov (United States)

Gordon, Alison D.; Buxton, Debra E.

2018-05-10

The U.S. Geological Survey, in cooperation with the New Jersey Department of Environmental Protection, conducted a study to simulate the effects of withdrawals from the Kirkwood-Cohansey aquifer system on streamflow and groundwater flow and from the Piney Point aquifer on water levels in the Cohansey and Maurice River Basins in Cumberland County and surrounding areas. The aquifer system consists of gravel, sand, silt, and clay sediments of the Cohansey Sand and Kirkwood Formation that dip and thicken to the southeast. The aquifer system is generally an unconfined aquifer, but semi-confined and confined conditions exist within the Cumberland County study area. The Kirkwood-Cohansey aquifer system is present throughout Cumberland County and is the principal source of groundwater for public, domestic, agricultural-irrigation, industrial, and commercial water uses. In 2008, reported groundwater withdrawals from the Kirkwood-Cohansey aquifer system in the study area totaled about 21,700 million gallons—about 36 percent for public supply; about 49 percent for agricultural irrigation; and about 15 percent for industrial, commercial, mining by sand and gravel companies, and non-agricultural irrigation uses. A transient numerical groundwater-flow model of the Kirkwood-Cohansey aquifer system was developed and calibrated by incorporating monthly recharge, base-flow estimates, water-level data, surface-water diversions and discharges, and groundwater withdrawals from 1998 to 2008.The groundwater-flow model was used to simulate five withdrawal scenarios to observe the effects of additional groundwater withdrawals on the Kirkwood-Cohansey aquifer system and streams. These scenarios include (1) average 1998 to 2008 monthly groundwater withdrawals (baseline scenario); (2) monthly full-allocation groundwater withdrawals, but agricultural-irrigation withdrawals were decreased for October through March; (3) monthly full-allocation groundwater withdrawals; (4) estimated monthly

Conceptual and numerical modeling approach of the Guarani Aquifer System

Science.gov (United States)

Rodríguez, L.; Vives, L.; Gomez, A.

2013-01-01

In large aquifers, relevant for their considerable size, regional groundwater modeling remains challenging given geologic complexity and data scarcity in space and time. Yet, it may be conjectured that regional scale groundwater flow models can help in understanding the flow system functioning and the relative magnitude of water budget components, which are important for aquifer management. The Guaraní Aquifer System is the largest transboundary aquifer in South America. It contains an enormous volume of water; however, it is not well known, being difficult to assess the impact of exploitation currently used to supply over 25 million inhabitants. This is a sensitive issue because the aquifer is shared by four countries. Moreover, an integrated groundwater model, and therefore a global water balance, were not available. In this work, a transient regional scale model for the entire aquifer based upon five simplified, equally plausible conceptual models represented by different hydraulic conductivity parametrizations is used to analyze the flow system and water balance components. Combining an increasing number of hydraulic conductivity zones and an appropriate set of boundary conditions, the hypothesis of a continuous sedimentary unit yielded errors within the calibration target in a regional sense. The magnitude of the water budget terms resulted very similar for all parametrizations. Recharge and stream/aquifer fluxes were the dominant components representing, on average, 84.2% of total inflows and 61.4% of total outflows, respectively. However, leakage was small compared to stream discharges of main rivers. For instance, the simulated average leakage for the Uruguay River was 8 m3 s-1 while the observed absolute minimum discharge was 382 m3 s-1. Streams located in heavily pumped regions switched from a gaining condition in early years to a losing condition over time. Water is discharged through the aquifer boundaries, except at the eastern boundary. On average

Elevated naturally occurring arsenic in a semiarid oxidizing system, Southern High Plains aquifer, Texas, USA

Science.gov (United States)

Scanlon, Bridget R.; Nicot, J.-P.; Reedy, R.C.; Kurtzman, D.; Mukherjee, A.; Nordstrom, D. Kirk

2009-01-01

High groundwater As concentrations in oxidizing systems are generally associated with As adsorption onto hydrous metal (Al, Fe or Mn) oxides and mobilization with increased pH. The objective of this study was to evaluate the distribution, sources and mobilization mechanisms of As in the Southern High Plains (SHP) aquifer, Texas, relative to those in other semiarid, oxidizing systems. Elevated groundwater As levels are widespread in the southern part of the SHP (SHP-S) aquifer, with 47% of wells exceeding the current EPA maximum contaminant level (MCL) of 10 μg/L (range 0.3–164 μg/L), whereas As levels are much lower in the north (SHP-N: 9% ⩾ As MCL of 10 μg/L; range 0.2–43 μg/L). The sharp contrast in As levels between the north and south coincides with a change in total dissolved solids (TDS) from 395 mg/L (median north) to 885 mg/L (median south). Arsenic is present as arsenate (As V) in this oxidizing system and is correlated with groundwater TDS (Spearman’s ρ = 0.57). The most likely current source of As is sorbed As onto hydrous metal oxides based on correlations between As and other oxyanion-forming elements (V, ρ = 0.88; Se, ρ = 0.54; B, ρ = 0.51 and Mo, ρ = 0.46). This source is similar to that in other oxidizing systems and constitutes a secondary source; the most likely primary source being volcanic ashes in the SHP aquifer or original source rocks in the Rockies, based on co-occurrence of As and F (ρ = 0.56), oxyanion-forming elements and SiO2 (ρ = 0.41), which are found in volcanic ashes. High groundwater As concentrations in some semiarid oxidizing systems are related to high evaporation. Although correlation of As with TDS in the SHP aquifer may suggest evaporative concentration, unenriched stable isotopes (δ2H: −65 to −27; δ18O: −9.1 to −4.2) in the SHP aquifer do not support evaporation. High TDS in the SHP aquifer is most likely related to upward movement of saline water from the underlying

Estimation of transit times in a Karst Aquifer system using environmental tracers: Application on the Jeita Aquifer system-Lebanon.

Science.gov (United States)

Doummar, Joanna; Hamdan, Ahmad

2016-04-01

the remaining 3 samples have Delta-Ne in the expected range between (10-35%). Moreover Tritium-Helium analysis has showed some radiogenic Helium (4He) in one sample along with lower tritium concentrations signifying a mixture of new groundwater with old groundwater (older than 50 yrs). Furthermore, this study is complemented with published analysis of a series of 26 artificial tracer experiments performed in the Jeita karst system (Doummar, 2012). Transit times calculated from tracer experiments ranged between 3 and 300 hours (12 days). The shortest ones were recorded in the Jeita subsurface conduit. While injections in sinkholes yielded moderate transit times, fissured matrix and unsaturated zone resulted in relatively long ones. In Lebanon this type of spatial groundwater age dating using environmental tracers was not applied to date, to the exception of grab sample analysis. A second round of sampling for Tritium-Helium, CFCs and SF6 analysis will be undertaken under different flow periods in February 2016 to validate the obtained results. References Geyer, T. 2008: Process-based characterization of flow and transport in karst aquifers at catchment scale. Dissertation, Georg-August-Universität Göttingen, 103 S. Geyer, T., and Doummar, J. 2013. Protection of the Jeita Spring: Bestimmung der mittleren Verweilzeit des Grundwassers im Einzugsgebiet der Jeita Quelle-Libanon. Special report. Protection of the Jeita Spring. Applied Geosciences. Georg August University, Göttingen.

In situ treatment of arsenic contaminated groundwater by aquifer iron coating: Experimental study.

Science.gov (United States)

Xie, Xianjun; Wang, Yanxin; Pi, Kunfu; Liu, Chongxuan; Li, Junxia; Liu, Yaqing; Wang, Zhiqiang; Duan, Mengyu

2015-09-15

In situ arsenic removal from groundwater by an aquifer iron coating method has great potential to be a cost effective and simple groundwater remediation technology, especially in rural and remote areas where groundwater is used as the main water source for drinking. The in situ arsenic removal technology was first optimized by simulating arsenic removal in various quartz sand columns under anoxic conditions. The effectiveness was then evaluated in an actual high-arsenic groundwater environment. The arsenic removal mechanism by the coated iron oxide/hydroxide was investigated under different conditions using scanning electron microscopy (SEM)/X-ray absorption spectroscopy, electron probe microanalysis, and Fourier transformation infrared spectroscopy. Aquifer iron coating method was developed via a 4-step alternating injection of oxidant, iron salt and oxygen-free water. A continuous injection of 5.0 mmol/L FeSO4 and 2.5 mmol/L NaClO for 96 h can form a uniform goethite coating on the surface of quartz sand without causing clogging. At a flow rate of 7.2 mL/min of the injection reagents, arsenic (as Na2HAsO4) and tracer fluorescein sodium to pass through the iron-coated quartz sand column were approximately at 126 and 7 column pore volumes, respectively. The retardation factor of arsenic was 23.0, and the adsorption capacity was 0.11 mol As per mol Fe. In situ arsenic removal from groundwater in an aquifer was achieved by simultaneous injections of As(V) and Fe(II) reagents. Arsenic fixation resulted from a process of adsorption/co-precipitation with fine goethite particles by way of bidentate binuclear complexes. Therefore, the study results indicate that the high arsenic removal efficiency of the in situ aquifer iron coating technology likely resulted from the expanded specific surface area of the small goethite particles, which enhanced arsenic sorption capability and/or from co-precipitation of arsenic on the surface of goethite particles. Copyright © 2015

Modelling stream aquifer seepage in an alluvial aquifer: an improved loosing-stream package for MODFLOW

Science.gov (United States)

Osman, Yassin Z.; Bruen, Michael P.

2002-07-01

Seepage from a stream, which partially penetrates an unconfined alluvial aquifer, is studied for the case when the water table falls below the streambed level. Inadequacies are identified in current modelling approaches to this situation. A simple and improved method of incorporating such seepage into groundwater models is presented. This considers the effect on seepage flow of suction in the unsaturated part of the aquifer below a disconnected stream and allows for the variation of seepage with water table fluctuations. The suggested technique is incorporated into the saturated code MODFLOW and is tested by comparing its predictions with those of a widely used variably saturated model, SWMS_2D simulating water flow and solute transport in two-dimensional variably saturated media. Comparisons are made of both seepage flows and local mounding of the water table. The suggested technique compares very well with the results of variably saturated model simulations. Most currently used approaches are shown to underestimate the seepage and associated local water table mounding, sometimes substantially. The proposed method is simple, easy to implement and requires only a small amount of additional data about the aquifer hydraulic properties.

Water-level altitudes 2013 and water-level changes in the Chicot, Evangeline, and Jasper aquifers and compaction 1973--2012 in the Chicot and Evangeline aquifers, Houston-Galveston region, Texas

Science.gov (United States)

Kasmarek, Mark C.; Johnson, Michaela R.; Ramage, Jason K.

2013-01-01

Most of the subsidence in the Houston-Galveston region, Texas, has occurred as a direct result of groundwater withdrawals for municipal supply, commercial and industrial use, and irrigation that depressured and dewatered the Chicot and Evangeline aquifers, thereby causing compaction mostly in the clay and silt layers of the aquifer sediments. This report, prepared by the U.S. Geological Survey in cooperation with the Harris-Galveston Subsidence District, City of Houston, Fort Bend Subsidence District, Lone Star Groundwater Conservation District, and Brazoria County Groundwater Conservation District, is one in an annual series of reports depicting water-level altitudes and water-level changes in the Chicot, Evangeline, and Jasper aquifers and measured compaction of subsurface sediments in the Chicot and Evangeline aquifers in the Houston-Galveston region. The report contains maps depicting approximate water-level altitudes for 2013 (represented by measurements made during December 2012-February 2013) for the Chicot, Evangeline, and Jasper aquifers; maps depicting 1-year (2012-13) water-level changes for each aquifer; maps depicting 5-year (2008--13) water-level changes for each aquifer; maps depicting long-term (1990-2013 and 1977-2013) water-level changes for the Chicot and Evangeline aquifers; a map depicting long-term (2000-13) water-level changes for the Jasper aquifer; a map depicting locations of borehole-extensometer sites; and graphs depicting measured compaction of subsurface sediments at the extensometers during 1973-2012. Tables listing the data used to construct each water-level map for each aquifer and the compaction graphs are included.

Searching for an Acidic Aquifer in the Rio Tinto Basin: First Geobiology Results of MARTE Project

Science.gov (United States)

Fernandez-Remolar, D. C.; Prieto-Ballesteros, O.; Stoker, C.

2004-01-01

Among the conceivable modern habitats to be explored for searching life on Mars are those potentially developed underground. Subsurface habitats are currently environments that, under certain physicochemical circumstances, have high thermal and hydrochemical stability [1, 2]. In planets like Mars lacking an atmospheric shield, such systems are obviously protected against radiation, which strongly alters the structure of biological macromolecules. Low porosity but fractured aquifers currently emplaced inside ancient volcano/sedimentary and hydrothermal systems act as excellent habitats [3] due to its thermal and geochemical properties. In these aquifers the temperature is controlled by a thermal balance between conduction and advection processes, which are driven by the rock composition, geological structure, water turnover of aquifers and heat generation from geothermal processes or chemical reactions [4]. Moreover, microbial communities based on chemolithotrophy can obtain energy by the oxidation of metallic ores that are currently associated to these environments. Such a community core may sustain a trophic web composed of non-autotrophic forms like heterotrophic bacteria, fungi and protozoa.

Geodatabase compilation of hydrogeologic, remote sensing, and water-budget-component data for the High Plains aquifer, 2011

Science.gov (United States)

Houston, Natalie A.; Gonzales-Bradford, Sophia L.; Flynn, Amanda T.; Qi, Sharon L.; Peterson, Steven M.; Stanton, Jennifer S.; Ryter, Derek W.; Sohl, Terry L.; Senay, Gabriel B.

2013-01-01

The High Plains aquifer underlies almost 112 million acres in the central United States. It is one of the largest aquifers in the Nation in terms of annual groundwater withdrawals and provides drinking water for 2.3 million people. The High Plains aquifer has gained national and international attention as a highly stressed groundwater supply primarily because it has been appreciably depleted in some areas. The U.S. Geological Survey has an active program to monitor the changes in groundwater levels for the High Plains aquifer and has documented substantial water-level changes since predevelopment: the High Plains Groundwater Availability Study is part of a series of regional groundwater availability studies conducted to evaluate the availability and sustainability of major aquifers across the Nation. The goals of the regional groundwater studies are to quantify current groundwater resources in an aquifer system, evaluate how these resources have changed over time, and provide tools to better understand a systems response to future demands and environmental stresses. The purpose of this report is to present selected data developed and synthesized for the High Plains aquifer as part of the High Plains Groundwater Availability Study. The High Plains Groundwater Availability Study includes the development of a water-budget-component analysis for the High Plains completed in 2011 and development of a groundwater-flow model for the northern High Plains aquifer. Both of these tasks require large amounts of data about the High Plains aquifer. Data pertaining to the High Plains aquifer were collected, synthesized, and then organized into digital data containers called geodatabases. There are 8 geodatabases, 1 file geodatabase and 7 personal geodatabases, that have been grouped in three categories: hydrogeologic data, remote sensing data, and water-budget-component data. The hydrogeologic data pertaining to the northern High Plains aquifer is included in three separate

Apports des analyses chimiques et isotopiques à la connaissance du fonctionnement des aquifères plio-quaternaire et turonien de la zone synclinale d'Essaouira, Maroc occidentalGeochemistry of Plio-Quaternary and Turonian aquifers in the Essaouira Basin, western Moroco

Science.gov (United States)

Mennani, A.; Blavoux, B.; Bahir, M.; Bellion, Y.; Jalal, M.; Daniel, M.

2001-05-01

The Essaouira synclinal zone is one of the Moroccan semi-arid zones with annual rainfalls not exceeding 300 mm yr -1 and very high potential evapo-transpiration of about 920 mm yr -1. This syncline with a Senonian axial zone is bordered by two diapiric structures of Triassic deposits: the Tidzi Diapir that outcrops in the east and south, and the hidden Essaouira diapir in the west, which was found by geophysics. This syncline contains two main superimposed aquifers. (i) The Plio-Quaternary aquifer consists of sands, sandstone and conglomerates and provides the main part of the water supply. This free-water table flows out towards the northwest and its surface is affected by significant piezometric variations. (ii) The calcareous dolomitic Turonian is a confined aquifer under the Senonian marls in the and in direct contact with the Plio-Quaternary. For a few years, the drinking water supply to the town of Essaouira has come from deep drillings. These two aquifers were sampled in June 1995 and in Januray 1996 after exceptional rainfalls. All waters have the same geochemical profile. The interpretation of the total dissolved solids and chloride content of Plio-Quaternary aquifers makes it possible to specify their origins. It emphasises, in particular, the source from the Ksob Wadi in the northeast and the role of the hidden Essaouira diapir. Nitrate levels were raised excessively, increasing at the same time as chloride concentrations during the rains of the winter of 1996, and underline the wells vulnerability to pastoral and domestic activities. The interpretation of O- and H-isotopes distinguishes two contrasting Plio-Quaternary and Turonian aquifers with an Atlantic origin for the rain recharge. A specific campaign was varried out in November 1996 to date water from the Turonian aquifer by 14C. Two boreholes draw water of several thousands years old.

Sources of high-chloride water and managed aquifer recharge in an alluvial aquifer in California, USA

Science.gov (United States)

O'Leary, David R.; Izbicki, John A.; Metzger, Loren F.

2015-11-01

As a result of pumping in excess of recharge, water levels in alluvial aquifers within the Eastern San Joaquin Groundwater Subbasin, 130 km east of San Francisco (California, USA), declined below sea level in the early 1950s and have remained so to the present. Chloride concentrations in some wells increased during that time and exceeded the US Environmental Protection Agency's secondary maximum contaminant level of 250 mg/L, resulting in removal of some wells from service. Sources of high-chloride water include irrigation return in 16 % of sampled wells and water from delta sediments and deeper groundwater in 50 % of sampled wells. Chloride concentrations resulting from irrigation return commonly did not exceed 100 mg/L, although nitrate concentrations were as high as 25 mg/L as nitrogen. Chloride concentrations ranged from less than 100-2,050 mg/L in wells affected by water from delta sediments and deeper groundwater. Sequential electromagnetic logs show movement of high-chloride water from delta sediments to pumping wells through permeable interconnected aquifer layers. δD and δ18O data show most groundwater originated as recharge along the front of the Sierra Nevada, but tritium and carbon-14 data suggest recharge rates in this area are low and have decreased over recent geologic time. Managed aquifer recharge at two sites show differences in water-level responses to recharge and in the physical movement of recharged water with depth related to subsurface geology. Well-bore flow logs also show rapid movement of water from recharge sites through permeable interconnected aquifer layers to pumping wells.

Sources of high-chloride water and managed aquifer recharge in an alluvial aquifer in California, USA

Science.gov (United States)

O'Leary, David; Izbicki, John A.; Metzger, Loren F.

2015-01-01

As a result of pumping in excess of recharge, water levels in alluvial aquifers within the Eastern San Joaquin Groundwater Subbasin, 130 km east of San Francisco (California, USA), declined below sea level in the early 1950s and have remained so to the present. Chloride concentrations in some wells increased during that time and exceeded the US Environmental Protection Agency’s secondary maximum contaminant level of 250 mg/L, resulting in removal of some wells from service. Sources of high-chloride water include irrigation return in 16 % of sampled wells and water from delta sediments and deeper groundwater in 50 % of sampled wells. Chloride concentrations resulting from irrigation return commonly did not exceed 100 mg/L, although nitrate concentrations were as high as 25 mg/L as nitrogen. Chloride concentrations ranged from less than 100–2,050 mg/L in wells affected by water from delta sediments and deeper groundwater. Sequential electromagnetic logs show movement of high-chloride water from delta sediments to pumping wells through permeable interconnected aquifer layers. δD and δ18O data show most groundwater originated as recharge along the front of the Sierra Nevada, but tritium and carbon-14 data suggest recharge rates in this area are low and have decreased over recent geologic time. Managed aquifer recharge at two sites show differences in water-level responses to recharge and in the physical movement of recharged water with depth related to subsurface geology. Well-bore flow logs also show rapid movement of water from recharge sites through permeable interconnected aquifer layers to pumping wells.

Contribution of environmental isotopes to the study of large aquifers in Morocco

International Nuclear Information System (INIS)

Kabbaj, A.; Zeryouhi, I.; Carlier, P.

1978-01-01

The geochemistry of environmental isotopes has been applied to several aquifers in Maroc, some of them quite large: Charf el Akab in the Tanger region, the Oum er Rbia basin and the Tadla aquifer, the free nappe of limnic limes tone in the Sais plane, and the lias limestone aquifer. The isotopic investigations on the basis of hydrogeochemical data have given more precise information on the supply conditions of these aquifers. The types of water of different origin from the Atlas or the phosphate plateau in the Sais plane and the Tadla basin have been distinguished, the supply from one aquifer to another Lias nappe which, via the flexures of the Sais plane, supplies the nappe of limic limestone has been assessed, the homogeneity or heterogeneity of these aquifers has been investigated as well as their impermeability, the Tadla aquifer and the special case of Charf el Akab compared with the marine region. The findings have proved the usefulness of these techniques and permitted a specification of the general conditions for their application. (orig.) [de

Biogeochemistry at a wetland sediment-alluvial aquifer interface in a landfill leachate plume

Science.gov (United States)

Lorah, M.M.; Cozzarelli, I.M.; Böhlke, J.K.

2009-01-01

The biogeochemistry at the interface between sediments in a seasonally ponded wetland (slough) and an alluvial aquifer contaminated with landfill leachate was investigated to evaluate factors that can effect natural attenuation of landfill leachate contaminants in areas of groundwater/surface-water interaction. The biogeochemistry at the wetland-alluvial aquifer interface differed greatly between dry and wet conditions. During dry conditions (low water table), vertically upward discharge was focused at the center of the slough from the fringe of a landfill-derived ammonium plume in the underlying aquifer, resulting in transport of relatively low concentrations of ammonium to the slough sediments with dilution and dispersion as the primary attenuation mechanism. In contrast, during wet conditions (high water table), leachate-contaminated groundwater discharged upward near the upgradient slough bank, where ammonium concentrations in the aquifer where high. Relatively high concentrations of ammonium and other leachate constituents also were transported laterally through the slough porewater to the downgradient bank in wet conditions. Concentrations of the leachate-associated constituents chloride, ammonium, non-volatile dissolved organic carbon, alkalinity, and ferrous iron more than doubled in the slough porewater on the upgradient bank during wet conditions. Chloride, non-volatile dissolved organic carbon (DOC), and bicarbonate acted conservatively during lateral transport in the aquifer and slough porewater, whereas ammonium and potassium were strongly attenuated. Nitrogen isotope variations in ammonium and the distribution of ammonium compared to other cations indicated that sorption was the primary attenuation mechanism for ammonium during lateral transport in the aquifer and the slough porewater. Ammonium attenuation was less efficient, however, in the slough porewater than in the aquifer and possibly occurred by a different sorption mechanism. A

Hydrology of aquifer systems in the Memphis area, Tennessee

Science.gov (United States)

Criner, James H.; Sun, P-C. P.; Nyman, Dale J.

1964-01-01

The Memphis area as described in .this report comprises about 1,300 square miles of the Mississippi embayment part of the Gulf Coastal Plain. The area is underlain by as much as 3,000 feet of sediments ranging in age from Cretaceous through Quaternary. In 1960, 150 mgd (million gallons per day) of water was pumped from the principal aquifers. Municipal pumpage accounted for almost half of this amount, and industrial pumpage a little more than half. About 90 percent of the water used in the area is derived from the '500-foot' sand, and most of the remainder is from the ?400-foot' sand; both sands are of Eocene age. A small amount of water for domestic use is pumped from the terrace deposits of Pliocene and Pleistocene age. Both the '500-foot' and the '1,400-foot' sands are artesian aquifers except in the southeastern part of the area; there the water level in wells in the '500-foot' sand is now below the overlying confining clay. Water levels in both aquifers have declined almost continuously since pumping began, but the rate of decline has increased rapidly since 1940. Water-level decline in the '1,400-foot' sand has been less pronounced since 1956. The cones of depression in both aquifers have expanded and deepened as a result of the annual increases in pumping, and an increase in hydraulic gradients has induced a greater flow of water into the area. Approximately 135 mgd entered the Memphis area through the '500-foot' sand aquifer in 1960, and, of this amount, 60 mgd originated as inflow from the east and about 75 mgd was derived from leakage from the terrace deposits, from the north, south, and west and from other sources. Of the water entering the '1,400-foot' sand, about 5 mgd was inflow from the east, and about half that amount was from each of the north, south, and west directions. The average rate of movement of water outside the area of heavy withdrawals is about 70 feet per year in the '500-foot' sand and about 40 feet per year in the '1,400-foot' sand

Water-level altitudes 2014 and water-level changes in the Chicot, Evangeline, and Jasper aquifers and compaction 1973-2013 in the Chicot and Evangeline aquifers, Houston-Galveston region, Texas

Science.gov (United States)

Kasmarek, Mark C.; Johnson, Michaela R.; Ramage, Jason K.

2014-01-01

Most of the land-surface subsidence in the Houston-Galveston region, Texas, has occurred as a direct result of groundwater withdrawals for municipal supply, commercial and industrial use, and irrigation that depressured and dewatered the Chicot and Evangeline aquifers, thereby causing compaction of the aquifer sediments, mostly in the fine-grained clay and silt layers. This report, prepared by the U.S. Geological Survey in cooperation with the Harris-Galveston Subsidence District, City of Houston, Fort Bend Subsidence District, Lone Star Groundwater Conservation District, and Brazoria County Groundwater Conservation District, is one in an annual series of reports depicting water-level altitudes and water-level changes in the Chicot, Evangeline, and Jasper aquifers and measured compaction of subsurface sediments in the Chicot and Evangeline aquifers in the Houston-Galveston region. The report contains maps depicting approximate 2014 water-level altitudes (represented by measurements made during December 2013–March 2014) for the Chicot, Evangeline, and Jasper aquifers; maps depicting 1-year (2013–14) water-level changes for each aquifer; maps depicting contoured 5-year (2009–14) water-level changes for each aquifer; maps depicting contoured long-term (1990–2014 and 1977–2014) water-level changes for the Chicot and Evangeline aquifers; a map depicting contoured long-term (2000–14) water-level changes for the Jasper aquifer; a map depicting locations of borehole-extensometer sites; and graphs depicting measured cumulative compaction of subsurface sediments at the borehole extensometers during 1973–2013. Tables listing the data used to construct each water-level map for each aquifer and the compaction graphs are included.

Water-level altitudes 2012 and water-level changes in the Chicot, Evangeline, and Jasper aquifers and compaction 1973-2011 in the Chicot and Evangeline aquifers, Houston-Galveston region, Texas

Science.gov (United States)

Kasmarek, Mark C.; Johnson, Michaela R.; Ramage, Jason K.

2012-01-01

Most of the subsidence in the Houston–Galveston region, Texas, has occurred as a direct result of groundwater withdrawals for municipal supply, commercial and industrial use, and irrigation that depressured and dewatered the Chicot and Evangeline aquifers and caused compaction of the clay layers of the aquifer sediments. This report—prepared by the U.S. Geological Survey in cooperation with the Harris– Galveston Subsidence District, City of Houston, Fort Bend Subsidence District, Lone Star Groundwater Conservation District, and Brazoria County Groundwater Conservation District—is one in an annual series of reports depicting water-level altitudes and water-level changes in the Chicot, Evangeline, and Jasper aquifers and compaction in the Chicot and Evangeline aquifers in the Houston–Galveston region. The report contains maps showing approximate water-level altitudes for 2012 (calculated from measurements of water levels in wells made during December 2011–February 2012) for the Chicot, Evangeline, and Jasper aquifers; maps showing 1-year (2011–12) water-level-altitude changes for each aquifer; maps showing 5-year (2007–12) water-levelaltitude changes for each aquifer; maps showing long-term (1990–2012 and 1977–2012) water-level-altitude changes for the Chicot and Evangeline aquifers; a map showing long-term (2000–12) water-level-altitude change for the Jasper aquifer; a map showing locations of borehole extensometer sites; and graphs showing measured compaction of subsurface sediments at the extensometers from 1973 (or later) through 2011. Tables listing the data that were used to construct each water-level map for each aquifer and the cumulative compaction graphs are included.

Lithological and hydrological influences on ground-water composition in a heterogeneous carbonate-clay aquifer system

Science.gov (United States)

Kauffman, S.J.; Herman, J.S.; Jones, B.F.

1998-01-01

The influence of clay units on ground-water composition was investigated in a heterogeneous carbonate aquifer system of Miocene age in southwest Florida, known as the Intermediate aquifer system. Regionally, the ground water is recharged inland, flows laterally and to greater depths in the aquifer systems, and is discharged vertically upward at the saltwater interface along the coast. A depth profile of water composition was obtained by sampling ground water from discrete intervals within the permeable carbonate units during coring and by squeezing pore water from a core of the less-permeable clay layers. A normative salt analysis of solute compositions in the water indicated a marine origin for both types of water and an evolutionary pathway for the clay water that involves clay diagenesis. The chemical composition of the ground water in the carbonate bedrock is significantly different from that of the pore water in the clay layers. Dissolution of clays and opaline silica results in high silica concentrations relative to water in other parts of the Intermediate aquifer system. Water enriched in chloride relative to the overlying and underlying ground water recharges the aquifer inland where the confining clay layer is absent, and it dissolves carbonate and silicate minerals and reacts with clays along its flow path, eventually reaching this coastal site and resulting in the high chloride and silica concentrations observed in the middle part of the Intermediate aquifer system. Reaction-path modeling suggests that the recharging surficial water mixes with sulfate-rich water upwelling from the Upper Floridan aquifer, and carbonate mineral dissolution and precipitation, weathering and exchange reactions, clay mineral diagenesis, clay and silica dissolution, organic carbon oxidation, and iron and sulfate reduction result in the observed water compositions.A study was conducted to clarify the influence of clay units on ground-water composition in a heterogeneous

Ground Water movement in crystalline rock aquifers

International Nuclear Information System (INIS)

Serejo, A.N.C.; Freire, C.; Siqueira, H.B. de; Frischkorn, H.; Torquato, J.R.F.; Santiago, M.M.F.; Barbosa, P.C.

1984-01-01

Ground water movement studies were performed in crystalline rock aquifers from the upper Acarau River hydrographic basin, state of Ceara, Brazil. The studies included carbon-14, 18 O/ 16 O and tritium measurements as well as chemical analysis. A total of 35 wells were surveyed during drought seasons. Carbon-14 values displayed little variation which implied that the water use was adequate despite of the slower recharge conditions. Fairly constant isotopic 18 O/ 16 O ratio values in the wells and their similarity with rainwater values indicated that the recharge is done exclusively by pluvial waters. A decreasing tendency within the tritium concentration values were interpreted as a periodic rainwater renewal for these aquifers. The chemical analysis demonstrated that there is in fact no correlation between salinity and the time the water remains in the aquifer itself. (D.J.M.) [pt

Water-level altitudes 2009 and water-level changes in the Chicot, Evangeline, and Jasper Aquifers and compaction 1973-2008 in the Chicot and Evangeline Aquifers, Houston-Galveston Region, Texas

Science.gov (United States)

Kasmarek, Mark C.; Houston, Natalie A.; Ramage, Jason K.

2009-01-01

This report, done in cooperation with the Harris-Galveston Subsidence District, the City of Houston, the Fort Bend Subsidence District, and the Lone Star Groundwater Conservation District, is one in an annual series of reports that depicts water-level altitudes and water-level changes in the Chicot, Evangeline, and Jasper aquifers, and compaction in the Chicot and Evangeline aquifers in the Houston-Galveston region, Texas. The report (excluding appendixes) contains 16 sheets and 15 tables: 3 sheets are maps showing current-year (2009) water-level altitudes for each aquifer, respectively; 3 sheets are maps showing 1-year (2008-09) water-level changes for each aquifer, respectively; 3 sheets are maps showing 5-year (2004-09) water-level changes for each aquifer, respectively; 4 sheets are maps showing long-term (1990-2009 and 1977-2009) water-level changes for the Chicot and Evangeline aquifers, respectively; 1 sheet is a map showing long-term (2000-2009) water-level change for the Jasper aquifer; 1 sheet is a map showing site locations of borehole extensometers; and 1 sheet comprises graphs showing measured compaction of subsurface material at the sites from 1973 or later through 2008, respectively. Tables listing the data used to construct the aquifer-data maps and the compaction graphs are included.

Water-level and recoverable water in storage changes, High Plains aquifer, predevelopment to 2015 and 2013–15

Science.gov (United States)

McGuire, Virginia L.

2017-06-01

The High Plains aquifer underlies 111.8 million acres (about 175,000 square miles) in parts of eight States—Colorado, Kansas, Nebraska, New Mexico, Oklahoma, South Dakota, Texas, and Wyoming. Water-level declines began in parts of the High Plains aquifer soon after the beginning of substantial irrigation with groundwater in the aquifer area (about 1950). This report presents water-level changes and change in recoverable water in storage in the High Plains aquifer from predevelopment (about 1950) to 2015 and from 2013 to 2015.The methods to calculate area-weighted, average water-level changes; change in recoverable water in storage; and total recoverable water in storage used geospatial data layers organized as rasters with a cell size of 500 meters by 500 meters, which is an area of about 62 acres. Raster datasets of water-level changes are provided for other uses.Water-level changes from predevelopment to 2015, by well, ranged from a rise of 84 feet to a decline of 234 feet. Water-level changes from 2013 to 2015, by well, ranged from a rise of 24 feet to a decline of 33 feet. The area-weighted, average water-level changes in the aquifer were an overall decline of 15.8 feet from predevelopment to 2015 and a decline of 0.6 feet from 2013 to 2015. Total recoverable water in storage in the aquifer in 2015 was about 2.91 billion acre-feet, which was a decline of about 273.2 million acre-feet since predevelopment and a decline of 10.7 million acre-feet from 2013 to 2015.

Hydrogeologic framework and hydrologic conditions of the Piney Point aquifer in Virginia

Science.gov (United States)

McFarland, E. Randolph

2017-06-07

Formation, the VA DEQ has considered regarding the limestone and sand singly as a regulated aquifer apart from the other geologic units. Under current policy in Virginia, if only the limestone and sand were regarded as a regulated aquifer, a greater amount of drawdown would be allowed than is allowed for the Piney Point aquifer consisting of six geologic units. Some production wells intercept multiple geologic units, and the units can undergo water-level decline and vertical leakage induced by pumping from the limestone and sand. Whether the other geologic units are to be regarded as regulated aquifers is an additional consideration for the VA DEQ.

Attachment and Detachment Behavior of Human Adenovirus and Surrogates in Fine Granular Limestone Aquifer Material.

Science.gov (United States)

Stevenson, Margaret E; Sommer, Regina; Lindner, Gerhard; Farnleitner, Andreas H; Toze, Simon; Kirschner, Alexander K T; Blaschke, Alfred P; Sidhu, Jatinder P S

2015-09-01

The transport of human adenovirus, nanoparticles, and PRD1 and MS2 bacteriophages was tested in fine granular limestone aquifer material taken from a borehole at a managed aquifer recharge site in Adelaide, South Australia. Comparison of transport and removal of virus surrogates with the pathogenic virus is necessary to understand the differences between the virus and surrogate. Because experiments using pathogenic viruses cannot be done in the field, laboratory tests using flow-through soil columns were used. Results show that PRD1 is the most appropriate surrogate for adenovirus in an aquifer dominated by calcite material but not under high ionic strength or high pH conditions. It was also found that straining due to size and the charge of the colloid were not dominant removal mechanisms in this system. Implications of this study indicate that a certain surrogate may not represent a specific pathogen solely based on similar size, morphology, and/or surface charge. Moreover, if a particular surrogate is representative of a pathogen in one aquifer system, it may not be the most appropriate surrogate in another porous media system. This was apparent in the inferior performance of MS2 as a surrogate, which is commonly used in virus transport studies. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

Continental hydrosystem modelling: the concept of nested stream-aquifer interfaces

Science.gov (United States)

Flipo, N.; Mouhri, A.; Labarthe, B.; Biancamaria, S.; Rivière, A.; Weill, P.

2014-08-01

Coupled hydrological-hydrogeological models, emphasising the importance of the stream-aquifer interface, are more and more used in hydrological sciences for pluri-disciplinary studies aiming at investigating environmental issues. Based on an extensive literature review, stream-aquifer interfaces are described at five different scales: local [10 cm-~10 m], intermediate [~10 m-~1 km], watershed [10 km2-~1000 km2], regional [10 000 km2-~1 M km2] and continental scales [>10 M km2]. This led us to develop the concept of nested stream-aquifer interfaces, which extends the well-known vision of nested groundwater pathways towards the surface, where the mixing of low frequency processes and high frequency processes coupled with the complexity of geomorphological features and heterogeneities creates hydrological spiralling. This conceptual framework allows the identification of a hierarchical order of the multi-scale control factors of stream-aquifer hydrological exchanges, from the larger scale to the finer scale. The hyporheic corridor, which couples the river to its 3-D hyporheic zone, is then identified as the key component for scaling hydrological processes occurring at the interface. The identification of the hyporheic corridor as the support of the hydrological processes scaling is an important step for the development of regional studies, which is one of the main concerns for water practitioners and resources managers. In a second part, the modelling of the stream-aquifer interface at various scales is investigated with the help of the conductance model. Although the usage of the temperature as a tracer of the flow is a robust method for the assessment of stream-aquifer exchanges at the local scale, there is a crucial need to develop innovative methodologies for assessing stream-aquifer exchanges at the regional scale. After formulating the conductance model at the regional and intermediate scales, we address this challenging issue with the development of an

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.

Landfill leachate effects on sorption of organic micropollutants onto aquifer materials

DEFF Research Database (Denmark)

Larsen, Thomas; Christensen, Thomas Højlund; Pfeffer, Fred M.

1992-01-01

The effect of dissolved organic carbon as present in landfill leachate, on the sorption of organic micropollutants in aquifer materials was studied by laboratory batch and column experiments involving 15 non-polar organic chemicals, 5 landfill leachates and 4 aquifer materials of low organic carbon......, the effect of landfill leachate on retardation of organic micropollutants in aquifer material seems limited....... content. The experiments showed that hydrophobic organic micropollutants do partition into dissolved organic carbon found in landfill leachate potentially increasing their mobility. However, landfill leachate interacted with aquifer materials apparently increases the sorbent affinity for the hydrophobic...

An Integrated Hydrogeologic and Geophysical Investigation to Characterize the Hydrostratigraphy of the Edwards Aquifer in an Area of Northeastern Bexar County, Texas

Science.gov (United States)

Shah, Sachin D.; Smith, Bruce D.; Clark, Allan K.; Payne, Jason

2008-01-01

In August 2007, the U.S. Geological Survey, in cooperation with the San Antonio Water System, did a hydrogeologic and geophysical investigation to characterize the hydrostratigraphy (hydrostratigraphic zones) and also the hydrogeologic features (karst features such as sinkholes and caves) of the Edwards aquifer in a 16-square-kilometer area of northeastern Bexar County, Texas, undergoing urban development. Existing hydrostratigraphic information, enhanced by local-scale geologic mapping in the area, and surface geophysics were used to associate ranges of electrical resistivities obtained from capacitively coupled (CC) resistivity surveys, frequency-domain electromagnetic (FDEM) surveys, time-domain electromagnetic (TDEM) soundings, and two-dimensional direct-current (2D-DC) resistivity surveys with each of seven hydrostratigraphic zones (equivalent to members of the Kainer and Person Formations) of the Edwards aquifer. The principal finding of this investigation is the relation between electrical resistivity and the contacts between the hydrostratigraphic zones of the Edwards aquifer and the underlying Trinity aquifer in the area. In general, the TDEM data indicate a two-layer model in which an electrical conductor underlies an electrical resistor, which is consistent with the Trinity aquifer (conductor) underlying the Edwards aquifer (resistor). TDEM data also show the plane of Bat Cave fault, a well-known fault in the area, to be associated with a local, nearly vertical zone of low resistivity that provides evidence, although not definitive, for Bat Cave fault functioning as a flow barrier, at least locally. In general, the CC resistivity, FDEM survey, and 2D-DC resistivity survey data show a sharp electrical contrast from north to south, changing from high resistivity to low resistivity across Bat Cave fault as well as possible karst features in the study area. Interpreted karst features that show relatively low resistivity within a relatively high

Saturated-unsaturated flow in a compressible leaky-unconfined aquifer

Science.gov (United States)

Mishra, Phoolendra K.; Vesselinov, Velimir V.; Kuhlman, Kristopher L.

2012-06-01

An analytical solution is developed for three-dimensional flow towards a partially penetrating large-diameter well in an unconfined aquifer bounded below by a leaky aquitard of finite or semi-infinite extent. The analytical solution is derived using Laplace and Hankel transforms, then inverted numerically. Existing solutions for flow in leaky unconfined aquifers neglect the unsaturated zone following an assumption of instantaneous drainage due to Neuman. We extend the theory of leakage in unconfined aquifers by (1) including water flow and storage in the unsaturated zone above the water table, and (2) allowing the finite-diameter pumping well to partially penetrate the aquifer. The investigation of model-predicted results shows that aquitard leakage leads to significant departure from the unconfined solution without leakage. The investigation of dimensionless time-drawdown relationships shows that the aquitard drawdown also depends on unsaturated zone properties and the pumping-well wellbore storage effects.

Hydrogeochemical study of water in some aquifers of the Estado de Mexico

International Nuclear Information System (INIS)

Pena, P.; Lopez, A.; Balcazar, M.; Flores, J.H.; Cardenas, S.; Schubert, M.

2005-01-01

The National Institute of Nuclear Research of Mexico (ININ), has developed a technique that allows to study the association of recharge mechanisms, residence times of the water in the aquifers, as well as the local lithology and the geochemical parameters. The viability of this technique was proven on November 2004 in the aquifers (La Perita, El Tunel y El Pedregal) located in the Asuncion Tepexoyuca, Estado de Mexico. It was observed that so much the aquifer El Tunel like La Perita are used for the human consumption, the aquifer of El Pedregal is used for the fish cultivation. The studies were carried out during March 2003 to November 2004. In the aquifer La Perita the maximum values of the radon concentration (0.76 Bq L -1 ) they were observed in the summertime time (December). In the spring El Tunel the maximum values of the radon concentration (4.08 Bq L -1 ) they were observed in the rainy season (September) this increment can be due to the contributions of the recharge of aquifers that it allows the haulage of the radon of other alternating roads of infiltration of the rain water. Of the physicochemical and radiochemical analyses carried out in the water samples of the studied aquifers, it is deduced that they are waters of good quality since for the human consumption since that they are inside on the maximum permissible limits as for their potability according to national and international standards. Likewise it was observed that the water of the aquifers is a single aquifer, since that its differences they due to the time of permanency of the water inside the aquifer. The classification of the underground water deduced that it is calcic and/or magnesic bi carbonated water belonging to the type of meteoric waters of recent infiltration. (Author)

Three-Dimensional Flow Generated by a Partially Penetrating Well in a Two-Aquifer System

Science.gov (United States)

Sepulveda, N.

2007-12-01

An analytical solution is presented for three-dimensional (3D) flow in a confined aquifer and the overlying storative semiconfining layer and unconfined aquifer. The equation describing flow caused by a partially penetrating production well is solved analytically to provide a method to accurately determine the hydraulic parameters in the confined aquifer, semiconfining layer, and unconfined aquifer from aquifer-test data. Previous solutions for a partially penetrating well did not account for 3D flow or storativity in the semiconfining unit. The 3D and two- dimensional (2D) flow solutions in the semiconfining layer are compared for various hydraulic conductivity ratios between the aquifer and the semiconfining layer. Analysis of the drawdown data from an aquifer test in central Florida showed that the 3D solution in the semiconfining layer provides a more unique identification of the hydraulic parameters than the 2D solution. The analytical solution could be used to analyze, with higher accuracy, the effect that pumping water from the lower aquifer in a two-aquifer system has on wetlands.

Aquifer restoration at uranium in situ leach sites

International Nuclear Information System (INIS)

Anastasi, F.S.; Williams, R.E.

1985-01-01

In situ mining of uranium involves injection of a leaching solution (lixiviant) into an ore-bearing aquifer. Frequently, the ground water in the mined aquifer is a domestic or livestock water supply. As the lixiviant migrates through the ore body, uranium and various associated elements such as arsenic, selenium, molybdenum, vanadium and radium-226 are mobilized in the ground water. Aquifer restoration after in situ mining is not fully understood. Several methods have been developed to restore mined aquifers to pre-mining (baseline) quality. Commonly used methods include ground water sweeping, clean water injection, and treatment by ion exchange and reverse osmosis technologies. Ammonium carbonate lixiviant was used at one RandD in situ mine. Attempts were made to restore the aquifer using a variety of methods. Efforts were successful in reducing concentrations of the majority of contaminants to baseline levels. Concentrations of certain parameters, however, remained at levels above baseline six months after restoration ceased. Relatively large quantities of ground water were processed in the restoration attempt considering the small size of the project (1.25 acre). More thorough characterization of the hydrogeology of the site may have enhanced the effectiveness of restoration and reduced potential environmental impacts associated with the project. This paper presents some of the findings of a research project conducted by the Mineral Resources Waste Management Team at the University of Idaho in Moscow, Idaho. Views contained herein do not reflect U.S. Nuclear Regulatory Commission policy

Water levels of the Ozark aquifer in northern Arkansas, 2013

Science.gov (United States)

Schrader, Tony P.

2015-07-13

The Ozark aquifer is the largest aquifer, both in area of outcrop and thickness, and the most important source of freshwater in the Ozark Plateaus physiographic province, supplying water to northern Arkansas, southeastern Kansas, southern Missouri, and northeastern Oklahoma. The study area includes 16 Arkansas counties lying completely or partially within the Ozark Plateaus of the Interior Highlands major physiographic division. The U.S. Geological Survey, in cooperation with the Arkansas Natural Resources Commission and the Arkansas Geological Survey, conducted a study of water levels in the Ozark aquifer within Arkansas. This report presents a potentiometric-surface map of the Ozark aquifer within the Ozark Plateaus of northern Arkansas, representing water-level conditions for the early spring of 2013 and selected water-level hydrographs.

ZVI (Fe0) desalination: catalytic partial desalination of saline aquifers

Science.gov (United States)

Antia, David D. J.

2018-05-01

Globally, salinization affects between 100 and 1000 billion m3 a-1 of irrigation water. The discovery that zero valent iron (ZVI, Fe0) could be used to desalinate water (using intra-particle catalysis in a diffusion environment) raises the possibility that large-scale in situ desalination of aquifers could be undertaken to support agriculture. ZVI desalination removes NaCl by an adsorption-desorption process in a multi-stage cross-coupled catalytic process. This study considers the potential application of two ZVI desalination catalyst types for in situ aquifer desalination. The feasibility of using ZVI catalysts when placed in situ within an aquifer to produce 100 m3 d-1 of partially desalinated water from a saline aquifer is considered.

Conceptual and numerical modeling approach of the Guarani Aquifer System

Directory of Open Access Journals (Sweden)

L. Rodríguez

2013-01-01

Full Text Available In large aquifers, relevant for their considerable size, regional groundwater modeling remains challenging given geologic complexity and data scarcity in space and time. Yet, it may be conjectured that regional scale groundwater flow models can help in understanding the flow system functioning and the relative magnitude of water budget components, which are important for aquifer management. The Guaraní Aquifer System is the largest transboundary aquifer in South America. It contains an enormous volume of water; however, it is not well known, being difficult to assess the impact of exploitation currently used to supply over 25 million inhabitants. This is a sensitive issue because the aquifer is shared by four countries. Moreover, an integrated groundwater model, and therefore a global water balance, were not available. In this work, a transient regional scale model for the entire aquifer based upon five simplified, equally plausible conceptual models represented by different hydraulic conductivity parametrizations is used to analyze the flow system and water balance components. Combining an increasing number of hydraulic conductivity zones and an appropriate set of boundary conditions, the hypothesis of a continuous sedimentary unit yielded errors within the calibration target in a regional sense. The magnitude of the water budget terms resulted very similar for all parametrizations. Recharge and stream/aquifer fluxes were the dominant components representing, on average, 84.2% of total inflows and 61.4% of total outflows, respectively. However, leakage was small compared to stream discharges of main rivers. For instance, the simulated average leakage for the Uruguay River was 8 m³ s⁻¹ while the observed absolute minimum discharge was 382 m³ s⁻¹. Streams located in heavily pumped regions switched from a gaining condition in early years to a losing condition over time. Water is discharged through

Summary of hydrologic testing of the Floridan aquifer system at Fort Stewart, coastal Georgia, 2009-2010

Science.gov (United States)

Gonthier, Gerald J.

2011-01-01

Two test wells were completed at Fort Stewart, coastal Georgia, to investigate the potential for using the Lower Floridan aquifer as a source of water to satisfy anticipated, increased water needs. The U.S. Geological Survey, in cooperation with the U.S. Department of the Army, completed hydrologic testing of the Floridan aquifer system at the study site, including flowmeter surveys, slug tests, and 24- and 72-hour aquifer tests by mid-March 2010. Analytical approaches and model simulation were applied to aquifer-test results to provide estimates of transmissivity and hydraulic conductivity of the multilayered Floridan aquifer system. Data from a 24-hour aquifer test of the Upper Floridan aquifer were evaluated by using the straight-line Cooper-Jacob analytical method. Data from a 72-hour aquifer test of the Lower Floridan aquifer were simulated by using axisymmetric model simulations. Results of aquifer testing indicated that the Upper Floridan aquifer has a transmissivity of 100,000 feet-squared per day, and the Lower Floridan aquifer has a transmissivity of 7,000 feet-squared per day. A specific storage for the Floridan aquifer system as a result of model calibration was 3E-06 ft–1. Additionally, during a 72-hour aquifer test of the Lower Floridan aquifer, a drawdown response was observed in two Upper Floridan aquifer wells, one of which was more than 1 mile away from the pumped well.

Groundwater reorganization in the Floridan aquifer following Holocene sea-level rise

Science.gov (United States)

Morrissey, Sheila K.; Clark, Jordan F.; Bennett, Michael; Richardson, Emily; Stute, Martin

2010-10-01

Sea-level fluctuations, particularly those associated with glacial-interglacial cycles, can have profound impacts on the flow and circulation of coastal groundwater: the water found at present in many coastal aquifers may have been recharged during the last glacial period, when sea level was over 100m lower than present, and thus is not in equilibrium with present recharge conditions. Here we show that the geochemistry of the groundwater found in the Floridan Aquifer System in south Florida is best explained by a reorganization of groundwater flow following the sea-level rise at the end of the Last Glacial Maximum approximately 18,000 years ago. We find that the geochemistry of the fresh water found in the upper aquifers at present is consistent with recharge from meteoric water during the last glacial period. The lower aquifer, however, consists of post-sea-level-rise salt water that is most similar to that of the Straits of Florida, though with some dilution from the residual fresh water from the last glacial period circulation. We therefore suggest that during the last glacial period, the entire Floridan Aquifer System was recharged with meteoric waters. After sea level rose, the increased hydraulic head reduced the velocity of the groundwater flow. This velocity reduction trapped the fresh water in the upper aquifers and initiated saltwater circulation in the lower aquifer.

Simulating the 2012 High Plains drought using three single column versions (SCM) of BUGS5

Science.gov (United States)

Medina, I. D.; Denning, S.

2013-12-01

The impact of changes in the frequency and severity of drought on fresh water sustainability is a great concern for many regions of the world. One such location is the High Plains, where the local economy is primarily driven by fresh water withdrawals from the Ogallala Aquifer, which accounts for approximately 30% of total irrigation withdrawals from all U.S. aquifers combined. Modeling studies that focus on the feedback mechanisms that control the climate and eco-hydrology during times of drought are limited, and have used conventional General Circulation Models (GCMs) with grid length scales ranging from one hundred to several hundred kilometers. Additionally, these models utilize crude statistical parameterizations of cloud processes for estimating sub-grid fluxes of heat and moisture and have a poor representation of land surface heterogeneity. For this research, we will focus on the 2012 High Plains drought and will perform numerical simulations using three single column versions (SCM) of BUGS5 (Colorado State University (CSU) GCM coupled to the Simple Biosphere Model (SiB3)) at multiple sites overlying the Ogallala Aquifer for the 2011-2012 periods. In the first version of BUGS5, the model will be used in its standard bulk setting (single atmospheric column coupled to a single instance of SiB3), secondly, the Super-Parameterized Community Atmospheric Model (SP-CAM), a cloud resolving model (CRM consists of 64 atmospheric columns), will replace the single CSU GCM atmospheric parameterization and will be coupled to a single instance of SiB3, and for the third version of BUGS5, an instance of SiB3 will be coupled to each CRM column of the SP-CAM (64 CRM columns coupled to 64 instances of SiB3). To assess the physical realism of the land-atmosphere feedbacks simulated at each site by all versions of BUGS5, differences in simulated energy and moisture fluxes will be computed between the 2011 and 2012 period and will be compared to differences calculated using

Water-level altitudes 2015 and water-level changes in the Chicot, Evangeline, and Jasper aquifers and compaction 1973-2014 in the Chicot and Evangeline aquifers, Houston-Galveston region, Texas

Science.gov (United States)

Kasmarek, Mark C.; Ramage, Jason K.; Houston, Natalie A.; Johnson, Michaela R.; Schmidt, Tiffany S.

2015-01-01

Most of the land-surface subsidence in the Houston-Galveston region, Texas, has occurred as a direct result of groundwater withdrawals for municipal supply, commercial and industrial use, and irrigation that depressured and dewatered the Chicot and Evangeline aquifers, thereby causing compaction of the aquifer sediments, mostly in the fine-grained silt and clay layers. This report, prepared by the U.S. Geological Survey in cooperation with the Harris-Galveston Subsidence District, City of Houston, Fort Bend Subsidence District, Lone Star Groundwater Conservation District, and Brazoria County Groundwater Conservation District, is one in an annual series of reports depicting water-level altitudes and water-level changes in the Chicot, Evangeline, and Jasper aquifers and measured cumulative compaction of subsurface sediments in the Chicot and Evangeline aquifers in the Houston-Galveston region. The report contains regional-scale maps depicting approximate 2015 water-level altitudes (represented by measurements made during December 2014–March 2015) for the Chicot, Evangeline, and Jasper aquifers; maps depicting 1-year (2014–15) water-level changes for each aquifer; maps depicting approximate contoured 5-year (2010–15) water-level changes for each aquifer; maps depicting approximate contoured long-term (1990–2015 and 1977–2015) water-level changes for the Chicot and Evangeline aquifers; a map depicting approximate contoured long-term (2000–15) water-level changes for the Jasper aquifer; a map depicting locations of borehole-extensometer sites; and graphs depicting measured cumulative compaction of subsurface sediments at the borehole extensometers during 1973–2014. Three tables listing the water-level data used to construct each water-level map for each aquifer and a table listing the measured cumulative compaction data for each extensometer site and graphs are included.

Assessing aquifer storage and recovery feasibility in the Gulf Coastal Plains of Texas

Directory of Open Access Journals (Sweden)

W. Benjamin Smith

2017-12-01

Full Text Available Study region: The Gulf Coast and Carrizo-Wilcox aquifer systems in the Gulf Coastal Plains of Texas. Study focus: Aquifer storage and recovery is a water storage alternative that is underutilized in Texas, a state with both long periods of drought and high intensity storms. Future water storage plans in Texas almost exclusively rely on surface reservoirs, subject to high evaporative losses. This study seeks to identify sites where aquifer storage and recovery (ASR may be successful, especially in recovery of injected waters, by analyzing publicly-available hydrogeologic data. Transmissivity, hydraulic gradient, well density, depth to aquifer, and depth to groundwater are used in a GIS-based index to determine feasibility of implementing an ASR system in the Gulf Coast and Carrizo-Wilcox aquifer systems. New hydrological insights for the region: Large regions of the central and northern Gulf Coast and the central and southern Carrizo-Wilcox aquifer systems are expected to be hydrologically feasible regions for ASR. Corpus Christi, Victoria, San Antonio, Bryan, and College Station are identified as possible cities where ASR would be a useful water storage strategy. Keywords: Aquifer storage and recovery (ASR, GIS, Gulf coast, Carrizo-Wilcox, Managed aquifer recharge (MAR

Fate of N-nitrosomorpholine in an anaerobic aquifer used for managed aquifer recharge: a column study.

Science.gov (United States)

Pitoi, M M; Patterson, B M; Furness, A J; Bastow, T P; McKinley, A J

2011-04-01

The fate of N-nitrosomorpholine (NMOR) was evaluated at microgram and nanogram per litre concentrations. Experiments were undertaken to simulate the passage of groundwater contaminants through a deep anaerobic pyritic aquifer system, as part of a managed aquifer recharge (MAR) strategy. Sorption studies demonstrated the high mobility of NMOR in the Leederville aquifer system, with retardation coefficients between 1.2 and 1.6. Degradation studies from a 351 day column experiment and a 506 day stop-flow column experiment showed an anaerobic biologically induced reductive degradation process which followed first order kinetics. A biological lag-time of less than 3 months and a transient accumulation of morpholine (MOR) were also noted during the degradation. Comparable half-life degradation rates of 40-45 days were observed over three orders of magnitude in concentration (200 ng L(-1) to 650 μg L(-1)). An inhibitory effect on microorganism responsible to the biodegradation of NMOR at 650 μg L(-1) or a threshold effect at 200 ng L(-1) was not observed during these experiments. Crown Copyright © 2011. Published by Elsevier Ltd. All rights reserved.

Hydrologic and isotopic study of the Quito aquifer

International Nuclear Information System (INIS)

Villalba, Fabio; Benalcazar, Julio; Garcia, Marco; Altamirano, Cesar; Altamirano, Homero; Sarasti, Santiago; Mancero, Maria; Leiva, Eduardo; Pino, Jose; Alulema, Rafael; Cedeno, Alberto; Burbano, Napoleon; Paquel, Efren; Becerra, Simon; Andrade, Graciela

2000-10-01

The dynamics of the Quito basin and surrounding area aquifers were determined through the use of stable and radioactive isotopes, and the monitoring of the freatic levels and of the bacteriological and physico-chemical quality of the water. A conceptual hydrodynamic model of the Quito aquifer was also proposed in order to establish in the future a sustainable management system

Hydrogeology and water-quality characteristics of the Lower Floridan aquifer in east-central Florida

Science.gov (United States)

O'Reilly, Andrew M.; Spechler, Rick M.; McGurk, Brian E.

2002-01-01

The hydrogeology and water-quality characteristics of the Lower Floridan aquifer and the relation of the Lower Floridan aquifer to the framework of the Floridan aquifer system were evaluated during a 6-year (1995-2001) study. The study area, a 7,500 square-mile area of east-central Florida, is underlain by three principal hydrogeologic units: the surficial aquifer system, the intermediate confining unit, and the Floridan aquifer system. The Floridan aquifer system, a carbonate-rock aquifer system composed of the Upper Floridan aquifer, a middle semiconfining unit, a middle confining unit, and the Lower Floridan aquifer, is the major source of water supply to east-central Florida. The Upper Floridan aquifer provides much of the water required to meet the current (2002) demand; however, the Lower Floridan aquifer is being used increasingly as a source of freshwater, particularly for municipal needs. For this reason, a better understanding of the aquifer is needed. The Lower Floridan aquifer is present throughout east-central Florida. The aquifer is composed of alternating beds of limestone and dolomite, and is characterized by abundant fractured dolomite zones and solution cavities. The altitude of the top of the Lower Floridan aquifer ranges from less than 600 feet below sea level in the northern part of the study area to more than 1,600 feet below sea level in the southwestern part. Thickness of the unit ranges from about 910 to 1,180 feet. The top of the Lower Floridan aquifer generally is marked by an increase in formation resistivity and by an increase in the occurrence of fractures and solution cavities within the carbonates. Also, a noticeable increase in borehole flow often marks the top of the unit. The bottom of the Lower Floridan aquifer is based on the first occurrence of evaporites. Ground-water in the Lower Floridan aquifer generally moves in a southwest-to-northeast direction across the study area. In September 1998, the altitude of the potentiometric

Confined aquifer vulnerability induced by a pumping well in a leakage area

Directory of Open Access Journals (Sweden)

X. Meng

2015-05-01

Full Text Available Due to the pollution of shallow groundwater and the rapid development of society and economy which consume more freshwater, the exploitation of confined groundwater is steadily increasing in north China. Therefore, the rapid decline of the confined groundwater head increases the risk of confined aquifer pollution by leaky recharge from shallow aquifers. In this paper, a quantitative method for assessing confined aquifer vulnerability to contamination due to pumping has been developed. This method is based on the shallow and confined groundwater flow model and the advection and dispersion in the aquitard, including sorption. The cumulative time for the pollutant concentration at the top boundary of confined aquifer exceeding the maximum allowable level is defined as the confined aquifer vulnerability index, which can be obtained by numerically solving the solute transport equation. A hypothetical example is chosen as a case study to illustrate the whole process. The results indicate that the proposed method is a practical and reasonable assessment method of confined aquifer vulnerability.

Transport and fate of engineered silver nanoparticles in aquifer media

Science.gov (United States)

Adrian, Y.; Schneidewind, U.; Azzam, R.

2016-12-01

Engineered silver nanoparticles (AgNPs) are used in various consumer and medical products due to their antimicrobial properties. Their transport behavior in the environment is still under investigation. Previous studies have been focusing on the transport of AgNPs in test systems with pure quartz sand or top soil materials, but studies investigating aquifer material are rare. However, the protection of groundwater resources is an important part in the protection of human health and the assurance of future economic activities. Therefore, expert knowledge regarding the transport, behavior and fate of engineered nanoparticles as potential contaminants in aquifers is essential. The transport and retention behavior of two commercially available engineered AgNPs (one stabilized with a polymere and one with a surfactant) in natural silicate-dominated aquifer material was investigated in saturated laboratory columns. For the experiments a mean grain size diameter of 0.7 mm was chosen with varying silt and clay contents to investigate their effect on the transport behavior of the AgNPs. Typical flow velocities were chosen to represent natural conditions. Particle concentration in the effluent was measured using ICP-MS and the finite element code HYDRUS-1D was used to model the transport and retention processes. The size of the silver nanoparticles in the effluent was analyzed using Flow Field-Flow Fractionation. The obtained results show that silt and clay contents as well as the stabilization of the AgNPs control the transport and retention of AgNPs. Increasing breakthrough was observed with decreasing clay and silt content.

Analysis of vertical flow during ambient and pumped conditions in four monitoring wells at the Pantex Plant, Carson County, Texas, July-September 2008

Science.gov (United States)

Stanton, Gregory P.; Thomas, Jonathan V.; Stoval, Jeffery

2009-01-01

The Pantex Plant is a U.S. Department of Energy/National Nuclear Security Administration (USDOE/NNSA)-owned, contractor-operated facility managed by Babcock & Wilcox Technical Services Pantex, LLC (B&W Pantex) in Carson County, Texas, approximately 17 miles northeast of Amarillo. The U.S. Geological Survey, in cooperation with B&W Pantex through the USDOE/NNSA, made a series of flowmeter measurements and collected other borehole geophysical logs during July–September 2008 to analyze vertical flow in screened intervals of four selected monitoring wells (PTX01–1012, PTX06–1044, PTX06–1056, and PTX06–1068) at the Pantex Plant. Hydraulic properties (transmissivity values) of the section of High Plains (Ogallala) aquifer penetrated by the wells also were computed. Geophysical data were collected under ambient and pumped flow conditions in the four monitoring wells. Unusually large drawdowns occurred at two monitoring wells (PTX06–1044 and PTX06–1056) while the wells were pumped at relatively low rates. A decision was made to redevelop those wells, and logs were run again after redevelopment in the two monitoring wells.

Unconfined aquifer response to infiltration basins and shallow pump tests

Science.gov (United States)

Ostendorf, David W.; DeGroot, Don J.; Hinlein, Erich S.

2007-05-01

SummaryWe measure and model the unsteady, axisymmetric response of an unconfined aquifer to delayed, arbitrary recharge. Water table drainage follows the initial elastic aquifer response, as modeled for uniform, instantaneous recharge by Zlotnik and Ledder [Zlotnik, V., Ledder, G., 1992. Groundwater flow in a compressible unconfined aquifer with uniform circular recharge. Water Resources Research 28(6), 1619-1630] and delayed drainage by Moench [Moench, A.F., 1995. Combining the Neuman and Boulton models for flow to a well in an unconfined aquifer. Ground Water 33(3), 378-384]. We extend their analyses with a convolution integral that models the delayed response of an aquifer to infiltration from a circular infiltration basin. The basin routes the hydrograph to the water table with a decay constant dependent on a Brooks and Corey [Brooks, R.H., Corey, A.T., 1966. Properties of porous media affecting fluid flow. Journal of the Irrigation and Drainage Division ASCE 92(2), 61-88] unsaturated permeability exponent. The resulting closed form model approaches Neuman's [Neuman, S.P., 1972. Theory of flow in unconfined aquifers considering delayed response of the water table. Water Resources Research 8(4), 1031-1045] partially penetrating pump test equation for a small source radius, instantaneous, uniform drainage and a shallow screen section. Irrigation pump data at a well characterized part of the Plymouth-Carver Aquifer in southeastern Massachusetts calibrate the small source model, while infiltration data from the closed drainage system of State Route 25 calibrate the infiltration basin model. The calibrated permeability, elasticity, specific yield, and permeability exponent are plausible and consistent for the pump and infiltration data sets.

Integrated and sustainable management of the shared aquifer systems in the Sahel region

International Nuclear Information System (INIS)

Edwerd, Mickel

2012-01-01

It highlights the project Justification, the long term objective, the specific objectives and the project implementation strategy. The countries which participate to this project are the following: Algeria, Benin, Burkina Faso, Cameroon, central African Republic, Chad, Gambia, Guinea-Bissau, Mali, Mauritania, Niger, Nigeria and Senegal. Regarding Aquifer System we have: Chad Basin, Liptako-Gourma Aquifer, Iullemeden Aquifer, Senegalo-Mauritanian Aquifer and Taoudeni/Tanezrouft Basin.

ALOPEX stochastic optimization for pumping management in fresh water coastal aquifers

International Nuclear Information System (INIS)

Stratis, P N; Saridakis, Y G; Zakynthinaki, M S; Papadopoulou, E P

2014-01-01

Saltwater intrusion in freshwater aquifers is a problem of increasing significance in areas nearby the coastline. Apart from natural disastrous phenomena, such as earthquakes or floods, intense pumping human activities over the aquifer areas may change the chemical composition of the freshwater aquifer. Working towards the direction of real time management of freshwater pumping from coastal aquifers, we have considered the deployment of the stochastic optimization Algorithm of Pattern Extraction (ALOPEX), coupled with several penalty strategies that produce convenient management policies. The present study, which further extents recently derived results, considers the analytical solution of a classical model for underground flow and the ALOPEX stochastic optimization technique to produce an efficient approach for pumping management over coastal aquifers. Numerical experimentation also includes a case study at Vathi area on the Greek island of Kalymnos, to compare with known results in the literature as well as to demonstrate different management strategies

Natural and EDTA-complexed lanthanides used as a geochemical probe for aquifers: a case study of Orleans valley's alluvial and karstic aquifers

International Nuclear Information System (INIS)

Le Borgne, F.; Treuil, M.; Joron, J.L.; Lepiller, M.

2005-01-01

The transit of chemical elements within the different parts of Orleans valley's aquifer is studied by two complementary methods. Those methods rely on the fractionation of lanthanides (Ln) during their migration in natural waters. The first method consists in studying natural lanthanides patterns within the watershed, at its entries and exits. second one lies on multi-tracer experiments with Ln-EDTA complexes. This work is completed through an observation network consisting of 52 piezometers set on a sand and gravel quarry, and the natural entries and exits of the aquifer. Orleans valley's aquifer, which is made of an alluvial watershed lying on a karstic aquifer, is mainly fed by Loire river via a large karstic network. At the entries of the aquifer (Loire river at Jargeau), the Ln concentrations in the dissolved fraction ( heavy Ln. On the other hand, the filtration of alluvial groundwater with high colloids content induces no significant Ln fractionation when the solution contains no strong chelating agent. Hence, the transit of natural and artificial Ln in Orleans valley aquifer can be explained by two complementary processes. (I) Decanting/filtering or, on the opposite, stirring of colloids. Those processes induce no important Ln fractionation. (2) Exchanges of Ln between solute complexes, colloids and sediments due to the presence of strong chelating agents. Those exchanges fractionate the Ln in the order of their stability constants. Considering the natural Ln fractionation that occurs in the Loire river and in the studied aquifer, the carbonates, the stability constants of which follow the order light Ln < heavy Ln, are the best candidates as natural strong chelating agents. From the hydrodynamic point of view, both tracer experiments and natural Ln concentrations show that the transfer of elements within the alluvial watershed is pulsed by the Loire river movements. During an ascent phase, the elements migrate away from and perpendicularly to the karstic

Environmental isotopic study of the Korama aquifers, south of Zinder (Niger)

International Nuclear Information System (INIS)

Zakara, Z.; Karbo, A.; Aranyossy, J.F.

1993-01-01

A first environmental isotope study has been carried out on the ''Korama'' aquifers located in the southern part of the city of Zinder (Niger). Preliminary interpretation confirms that most of the aquifers are presently recharged by direct infiltration of rainwater. Structural fractures seem to play an important role in the water circulation allowing vertical drainage of oldest water coming from deeper aquifers and facilitating the recharge by surface water in the prheatic zone. It does not appear any difference between the so-called ''superficial Korama'' and the ''Deep Korama'' aquifers on the basis of the isotopic compositions. (author). 11 refs, 7 figs, 2 tabs

Mapping Greenland's Firn Aquifer using L-band Microwave Radiometry

Science.gov (United States)

Miller, J.; Bringer, A.; Jezek, K. C.; Johnson, J. T.; Scambos, T. A.; Long, D. G.

2016-12-01

Greenland's recently discovered firn aquifer is one of the most interesting, yet still mysterious, components of the ice sheet system. Many open questions remain regarding timescales of refreezing and/or englacial drainage of liquid meltwater, and the connections of firn aquifers to the subglacial hydrological system. If liquid meltwater production at the surface of the Greenland ice sheet continues to increase, subsequent increases in the volume of mobile liquid meltwater retained within Greenland's firn aquifer may increase the possibility of crevasse-deepening via hydrofracture. Hydrofracture is an important component of supraglacial lake drainage leading to at least temporary accelerated flow velocities and ice sheet mass balance changes. Firn aquifers may also support hydrofracture-induced drainage and thus are potentially capable of significantly influencing ice sheet mass balance and sea level rise. Spaceborne L-band microwave radiometers provide an innovative tool for ice-sheet wide mapping of the spatiotemporal variability of Greenland's firn aquifer. Both refreezing and englacial drainage may be observable given the sensitivity of the microwave response to the upper surface of liquid meltwater retained within snow and firn pore space as well as the ability of L band instruments to probe the ice sheet from the surface to the firn-ice transition at pore close-off depth. Here we combine L-band (1.4 GHz) brightness temperature observations from multiple sources to demonstrate the potential of mapping firn aquifers on ice sheets using L-band microwave radiometry. Data sources include the interferometric MIRAS instrument aboard ESA's Soil Moisture and Ocean Salinity (SMOS) satellite mission and the radiometer aboard NASA's Soil Moisture Active Passive (SMAP) satellite mission. We will also present mulit-frequency L-band brightness temperature data (0.5-2 GHz) that will be collected over several firn aquifer areas on the Greenland ice sheet by the Ohio State

Integrated Assessment to Evaluate the Artificial Recharge in a Small Portion of the Aquifer of Puebla, Mexico

Science.gov (United States)

Arango-Galván, C.; Flores-Marquez, L. E.; Martínez-Serrano, R.

2009-12-01

New policies on the use of water resources in Mexico have led to implement some alternative measures to optimize water management. In particular, water regulation entities have recommended some tools to preserve and protect the groundwater supplies. One of these tools is the artificial recharge by injecting water directly into the aquifer. The main goal of this study is to assess if it is suitable to inject rainwater and surface water in a small portion of the aquifer of the city of Puebla, in central Mexico. Artificial aquifer recharging was evaluated using a numeric model, which simulated the physical properties of the system. The model setup was inferred from an integrated study taking into account hydraulic, geological and geophysical data. The geoelectrical model was computed using electric resistivity tomography (ERT) and time domain electromagnetic data (TDEM). The aquifer geological structure inferred from geophysics depicts the presence of a shallower layer composed of sand and clay deposits with low saturation and permeability. This layer contains silt lenses that can be controlling the persistence of small water bodies on surface. Some water surficial bodies seem to be isolated from the main aquifer system. The intermediate layer shows lower electrical resistivity and higher permeability. Underlying this horizon, it is a deeper layer that reaches 200 m depth, according to information obtained from borehole in the zone. This layer shows an electrical resistivity even lower than intermediate layer but low permeability, caused by the higher content of silts. Both of these layers are the shallower aquifer exploited in the area. Once the numeric model was built we proceeded to simulate scenarios that include the continued extraction and recharge of water in wells located in strategic areas of the study zone. The results suggest that the effect of infiltration is beneficial on aquifer recharge and reduces the cone of depression caused by the extraction

The thermal impact of aquifer thermal energy storage (ATES) systems: a case study in the Netherlands, combining monitoring and modeling

Science.gov (United States)

Visser, Philip W.; Kooi, Henk; Stuyfzand, Pieter J.

2015-05-01

Results are presented of a comprehensive thermal impact study on an aquifer thermal energy storage (ATES) system in Bilthoven, the Netherlands. The study involved monitoring of the thermal impact and modeling of the three-dimensional temperature evolution of the storage aquifer and over- and underlying units. Special attention was paid to non-uniformity of the background temperature, which varies laterally and vertically in the aquifer. Two models were applied with different levels of detail regarding initial conditions and heterogeneity of hydraulic and thermal properties: a fine-scale heterogeneity model which construed the lateral and vertical temperature distribution more realistically, and a simplified model which represented the aquifer system with only a limited number of homogeneous layers. Fine-scale heterogeneity was shown to be important to accurately model the ATES-impacted vertical temperature distribution and the maximum and minimum temperatures in the storage aquifer, and the spatial extent of the thermal plumes. The fine-scale heterogeneity model resulted in larger thermally impacted areas and larger temperature anomalies than the simplified model. The models showed that scattered and scarce monitoring data of ATES-induced temperatures can be interpreted in a useful way by groundwater and heat transport modeling, resulting in a realistic assessment of the thermal impact.

Arsenic control during aquifer storage recovery cycle tests in the Floridan Aquifer.

Science.gov (United States)

Mirecki, June E; Bennett, Michael W; López-Baláez, Marie C

2013-01-01