Have We Overestimated Saline Aquifer CO2 Storage Capacities?

International Nuclear Information System (INIS)

Thibeau, S.; Mucha, V.

2011-01-01

During future, large scale CO 2 geological storage in saline aquifers, fluid pressure is expected to rise as a consequence of CO 2 injection, but the pressure build up will have to stay below specified values to ensure a safe and long term containment of the CO 2 in the storage site. The pressure build up is the result of two different effects. The first effect is a local overpressure around the injectors, which is due to the high CO 2 velocities around the injectors, and which can be mitigated by adding CO 2 injectors. The second effect is a regional scale pressure build up that will take place if the storage aquifer is closed or if the formation water that flows away from the pressurised area is not large enough to compensate volumetrically the CO 2 injection. This second effect cannot be mitigated by adding additional injectors. In the first section of this paper, we review some major global and regional assessments of CO 2 storage capacities in deep saline aquifers, in term of mass and storage efficiency. These storage capacities are primarily based on a volumetric approach: storage capacity is the volumetric sum of the CO 2 that can be stored through various trapping mechanisms. We then discuss in Section 2 storage efficiencies derived from a pressure build up approach, as stated in the CO2STORE final report (Chadwick A. et al. (eds) (2008) Best Practice for the Storage of CO 2 in Saline Aquifers, Observations and Guidelines from the SACS and CO2STORE Projects, Keyworth, Nottingham, BGS Occasional Publication No. 14) and detailed by Van der Meer and Egberts (van der Meer L.G.H., Egberts P.J.P. (2008) A General Method for Calculating Subsurface CO 2 Storage Capacity, OTC Paper 19309, presented at the OTC Conference held in Houston, Texas, USA, 5-8 May). A quantitative range of such storage efficiency is presented, based on a review of orders of magnitudes of pore and water compressibilities and allowable pressure increase. To illustrate the relevance of this

Environmental isotope studies related to groundwater flow and saline encroachment in the chalk aquifer of Lincolnshire, England

International Nuclear Information System (INIS)

Lloyd, J.W.; Howard, K.W.F.

1978-01-01

The isotopes of tritium and carbon are used to study part of the North Lincolnshire Chalk aquifer in England. The tritium data support the view that the aquifer is a thin fissure system and indicate that some changes in flow direction have occurred due to recent abstraction. The data are also consistent with other chemical data in elucidating groundwater entering the Chalk from deeper aquifers. Carbon isotopes are used to distinguish between saline water bodies and suggest that saline water was entrapped within the aquifer in the Eemian and Flandrian stages of the Pleistocene. (orig.) [de

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.

What Drives Saline Circulation Cells in Coastal Aquifers? An Energy Balance for Density-Driven Groundwater Systems

Science.gov (United States)

Harvey, C. F.; Michael, H. A.

2017-12-01

We formulate the energy balance for coastal groundwater systems and apply it to: (1) Explain the energy driving offshore saline circulation cells, and; (2) Assess the accuracy of numerical simulations of coastal groundwater systems. The flow of fresh groundwater to the ocean is driven by the loss of potential energy as groundwater drops from the elevation of the inland watertable, where recharge occurs, to discharge at sea level. This freshwater flow creates an underlying circulation cell of seawater, drawn into coastal aquifers offshore and discharging near shore, that adds to total submarine groundwater discharge. The saline water in the circulation cell enters and exits the aquifer through the sea floor at the same hydraulic potential. Existing theory explains that the saline circulation cell is driven by mixing of fresh and saline without any additional source of potential or mechanical power. This explanation raises a basic thermodynamic question: what is the source of energy that drives the saline circulation cell? Here, we resolve this question by building upon Hubbert's conception of hydraulic potential to formulate an energy balance for density-dependent flow and salt transport through an aquifer. We show that, because local energy dissipation within the aquifer is proportional to the square of the groundwater velocity, more groundwater flow may be driven through an aquifer for a given energy input if local variations in velocity are smoothed. Our numerical simulations of coastal groundwater systems show that dispersion of salt across the fresh-saline interface spreads flow over larger volumes of the aquifer, smoothing the velocity field, and increasing total flow and submarine groundwater discharge without consuming more power. The energy balance also provides a criterion, in addition to conventional mass balances, for judging the accuracy of numerical solutions of non-linear density-dependent flow problems. Our results show that some numerical

Carbon dioxide (CO2) sequestration in deep saline aquifers and formations: Chapter 3

Science.gov (United States)

Rosenbauer, Robert J.; Thomas, Burt

2010-01-01

Carbon dioxide (CO2) capture and sequestration in geologic media is one among many emerging strategies to reduce atmospheric emissions of anthropogenic CO2. This chapter looks at the potential of deep saline aquifers – based on their capacity and close proximity to large point sources of CO2 – as repositories for the geologic sequestration of CO2. The petrochemical characteristics which impact on the suitability of saline aquifers for CO2 sequestration and the role of coupled geochemical transport models and numerical tools in evaluating site feasibility are also examined. The full-scale commercial CO2 sequestration project at Sleipner is described together with ongoing pilot and demonstration projects.

Origins and processes of groundwater salinization in the urban coastal aquifers of Recife (Pernambuco, Brazil): A multi-isotope approach

International Nuclear Information System (INIS)

Cary, Lise; Petelet-Giraud, Emmanuelle; Bertrand, Guillaume; Kloppmann, Wolfram; Aquilina, Luc; Martins, Veridiana; Hirata, Ricardo; Montenegro, Suzana; Pauwels, Hélène; Chatton, Eliot; Franzen, Melissa; Aurouet, Axel; Lasseur, Eric; Picot, Géraldine; Guerrot, Catherine; Fléhoc, Christine

2015-01-01

In the coastal multilayer aquifer system of a highly urbanized southern city (Recife, Brazil), where groundwaters are affected by salinization, a multi-isotope approach (Sr, B, O, H) was used to investigate the sources and processes of salinization. The high diversity of the geological bodies, built since the Atlantic opening during the Cretaceous, highly constrains the heterogeneity of the groundwater chemistry, e.g. Sr isotope ratios, and needs to be integrated to explain the salinization processes and groundwater pathways. A paleoseawater intrusion, most probably the 120 ky B.P. Pleistocene marine transgression, and cationic exchange are clearly evidenced in the most salinized parts of the Cabo and Beberibe aquifers. All 87 Sr/ 86 Sr values are above the past and present-day seawater signatures, meaning that the Sr isotopic signature is altered due to additional Sr inputs from dilution with different freshwaters, and water–rock interactions. Only the Cabo aquifer presents a well-delimitated area of Na-HCO 3 water typical of a freshening process. The two deep aquifers also display a broad range of B concentrations and B isotope ratios with values among the highest known to date (63–68.5‰). This suggests multiple sources and processes affecting B behavior, among which mixing with saline water, B sorption on clays and mixing with wastewater. The highly fractionated B isotopic values were explained by infiltration of relatively salty water with B interacting with clays, pointing out the major role played by (palaeo)-channels for the deep Beberibe aquifer recharge. Based on an increase of salinity at the end of the dry season, a present-day seawater intrusion is identified in the surficial Boa Viagem aquifer. Our conceptual model presents a comprehensive understanding of the major groundwater salinization pathways and processes, and should be of benefit for other southern Atlantic coastal aquifers to better address groundwater management issues. - Highlights: �

Ground-water flow and saline water in the shallow aquifer system of the southern watersheds of Virginia Beach, Virginia

Science.gov (United States)

Smith, Barry S.

2003-01-01

Population and tourism continues to grow in Virginia Beach, Virginia, but the supply of freshwater is limited. A pipeline from Lake Gaston supplies water for northern Virginia Beach, but ground water is widely used to water lawns in the north, and most southern areas of the city rely solely on ground water. Water from depths greater than 60 meters generally is too saline to drink. Concentrations of chloride, iron, and manganese exceed drinking-water standards in some areas. The U.S. Geological Survey, in cooperation with the city of Virginia Beach, Department of Public Utilities, investigated the shallow aquifer system of the southern watersheds to determine the distribution of fresh ground water, its potential uses, and its susceptibility to contamination. Aquifers and confining units of the southern watersheds were delineated and chloride concentrations in the aquifers and confining units were contoured. A ground-water-flow and solute-transport model of the shallow aquifer system reached steady state with regard to measured chloride concentrations after 31,550 years of freshwater recharge. Model simulations indicate that if freshwater is found in permeable sediments of the Yorktown-Eastover aquifer, such a well field could supply freshwater, possibly for decades, but eventually the water would become more saline. The rate of saline-water intrusion toward the well field would depend on the rate of pumping, aquifer properties, and on the proximity of the well field to saline water sources. The steady-state, ground-water-flow model also was used to simulate drawdowns around two hypothetical well fields and drawdowns around two hypothetical open-pit mines. The chloride concentrations simulated in the model did not approximate the measured concentrations for some wells, indicating sites where local hydrogeologic units or unit properties do not conform to the simple hydrogeology of the model. The Columbia aquifer, the Yorktown confining unit, and the Yorktown

A geochemical approach to determine sources and movement of saline groundwater in a coastal aquifer.

Science.gov (United States)

Anders, Robert; Mendez, Gregory O; Futa, Kiyoto; Danskin, Wesley R

2014-01-01

Geochemical evaluation of the sources and movement of saline groundwater in coastal aquifers can aid in the initial mapping of the subsurface when geological information is unavailable. Chloride concentrations of groundwater in a coastal aquifer near San Diego, California, range from about 57 to 39,400 mg/L. On the basis of relative proportions of major-ions, the chemical composition is classified as Na-Ca-Cl-SO4, Na-Cl, or Na-Ca-Cl type water. δ(2)H and δ(18)O values range from -47.7‰ to -12.8‰ and from -7.0‰ to -1.2‰, respectively. The isotopically depleted groundwater occurs in the deeper part of the coastal aquifer, and the isotopically enriched groundwater occurs in zones of sea water intrusion. (87)Sr/(86)Sr ratios range from about 0.7050 to 0.7090, and differ between shallower and deeper flow paths in the coastal aquifer. (3)H and (14)C analyses indicate that most of the groundwater was recharged many thousands of years ago. The analysis of multiple chemical and isotopic tracers indicates that the sources and movement of saline groundwater in the San Diego coastal aquifer are dominated by: (1) recharge of local precipitation in relatively shallow parts of the flow system; (2) regional flow of recharge of higher-elevation precipitation along deep flow paths that freshen a previously saline aquifer; and (3) intrusion of sea water that entered the aquifer primarily during premodern times. Two northwest-to-southeast trending sections show the spatial distribution of the different geochemical groups and suggest the subsurface in the coastal aquifer can be separated into two predominant hydrostratigraphic layers. © 2013, National Ground Water Association.

Origin and distribution of saline groundwaters in the upper Miocene aquifer system, coastal Rhodope area, northeastern Greece

Science.gov (United States)

Petalas, C. P.; Diamantis, I. B.

1999-06-01

This paper describes the origins and distribution of saline groundwaters in the coastal area of Rhodope, Greece. The aquifer system includes two aquifers within coarse-grained alluvial sediments in the coastal part of the study area. Two major water-quality groups occur in the study area, namely Ca2+-rich saline groundwater and Ca2+-poor, almost fresh groundwater. The main process controlling the groundwater chemistry is the exchange of calcium and sodium between the aquifer matrix and intruding seawater. The natural salt water in the study area is probably residual water that infiltrated the aquifer system during repeated marine transgressions in late Pleistocene time. Seawater intrusion into the coastal aquifer system occurs as a result of overpumping in two seawater wedges separated vertically by a low-permeability layer. The rate of intrusion averages 0.8 m/d and is less than expected due to a decline of the aquifer's permeability at the interface with the seawater. The application of several hydrochemical techniques (Piper and Durov diagrams; Na+/Cl-, Ca2+/Cl-, Mg2+/Cl-, and Br-/Cl- molar ratios; Ca2+/Mg2+ weight ratio; and chloride concentrations), combined with field observations, may lead to a better explanation of the origin of the saline groundwater.

Hurricane Ingrid and Tropical Storm Hanna's effects on the salinity of the coastal aquifer, Quintana Roo, Mexico

Science.gov (United States)

Kovacs, Shawn E.; Reinhardt, Eduard G.; Stastna, Marek; Coutino, Aaron; Werner, Christopher; Collins, Shawn V.; Devos, Fred; Le Maillot, Christophe

2017-08-01

There is a lack of information on aquifer dynamics in anchialine systems, especially in the Yucatán Peninsula of Mexico. Most of our knowledge is based on ;spot; measurements of the aquifer with no long-term temporal monitoring. In this study spanning four years (2012-2016), sensors (water depth and conductivity (salinity)) were deployed and positioned (-9 and -10 m) in the meteoric Water Mass (WM) close to the transition with the marine WM (halocline) in 2 monitoring sites within the Yax Chen cave system to investigate precipitation effects on the salinity of the coastal aquifer. The results show variation in salinity (95 mm) such as Hurricane Ingrid (2013) and Tropical Storm Hanna (2014) shows meteoric water mass salinity rapidly increasing (approx. 6.39 to >8.6 ppt), but these perturbations have a shorter duration (weeks and days). Wavelet analysis of the salinity record indicates seasonal mixing effects in agreement with the wet and dry periods, but also seasonal effects of tidal mixing (meteoric and marine water masses) occurring on shorter time scales (diurnal and semi-diurnal). These results demonstrate that the salinity of the freshwater lens is influenced by precipitation and turbulent mixing with the marine WM. The salinity response is scaled with precipitation; larger more intense rainfall events (>95 mm) create a larger response in terms of the magnitude and duration of the salinity perturbation (>1 ppt). The balance of precipitation and its intensity controls the temporal and spatial patterning of meteoric WM salinity.

Origins and processes of groundwater salinization in the urban coastal aquifers of Recife (Pernambuco, Brazil): A multi-isotope approach

Energy Technology Data Exchange (ETDEWEB)

Cary, Lise, E-mail: l.cary@brgm.fr [BRGM French Geological Survey, 3 Avenue Claude Guillemin, 45060 Orléans Cedex 2 (France); Petelet-Giraud, Emmanuelle [BRGM French Geological Survey, 3 Avenue Claude Guillemin, 45060 Orléans Cedex 2 (France); Bertrand, Guillaume [Institute of Geosciences, University of São Paulo, Rua do Lago, 562 Butantã, 05508-080 Sao Paulo (Brazil); Kloppmann, Wolfram [BRGM French Geological Survey, 3 Avenue Claude Guillemin, 45060 Orléans Cedex 2 (France); Aquilina, Luc [OSUR-Géosciences Rennes, Université Rennes 1 — CNRS, 35000 Rennes (France); Martins, Veridiana; Hirata, Ricardo [Institute of Geosciences, University of São Paulo, Rua do Lago, 562 Butantã, 05508-080 Sao Paulo (Brazil); Montenegro, Suzana [Civil Engineering Department, Federal University of Pernambuco, 50740 Recife, PE Brazil (Brazil); Pauwels, Hélène [BRGM French Geological Survey, 3 Avenue Claude Guillemin, 45060 Orléans Cedex 2 (France); Chatton, Eliot [OSUR-Géosciences Rennes, Université Rennes 1 — CNRS, 35000 Rennes (France); Franzen, Melissa [CPRM, Brazilian Geologic Survey, Avenida Sul 2291, Recife PE (Brazil); Aurouet, Axel [Géo-Hyd, 101 rue Jacques Charles, 45160 Olivet (France); Lasseur, Eric; Picot, Géraldine; Guerrot, Catherine; Fléhoc, Christine [BRGM French Geological Survey, 3 Avenue Claude Guillemin, 45060 Orléans Cedex 2 (France); and others

2015-10-15

In the coastal multilayer aquifer system of a highly urbanized southern city (Recife, Brazil), where groundwaters are affected by salinization, a multi-isotope approach (Sr, B, O, H) was used to investigate the sources and processes of salinization. The high diversity of the geological bodies, built since the Atlantic opening during the Cretaceous, highly constrains the heterogeneity of the groundwater chemistry, e.g. Sr isotope ratios, and needs to be integrated to explain the salinization processes and groundwater pathways. A paleoseawater intrusion, most probably the 120 ky B.P. Pleistocene marine transgression, and cationic exchange are clearly evidenced in the most salinized parts of the Cabo and Beberibe aquifers. All {sup 87}Sr/{sup 86}Sr values are above the past and present-day seawater signatures, meaning that the Sr isotopic signature is altered due to additional Sr inputs from dilution with different freshwaters, and water–rock interactions. Only the Cabo aquifer presents a well-delimitated area of Na-HCO{sub 3} water typical of a freshening process. The two deep aquifers also display a broad range of B concentrations and B isotope ratios with values among the highest known to date (63–68.5‰). This suggests multiple sources and processes affecting B behavior, among which mixing with saline water, B sorption on clays and mixing with wastewater. The highly fractionated B isotopic values were explained by infiltration of relatively salty water with B interacting with clays, pointing out the major role played by (palaeo)-channels for the deep Beberibe aquifer recharge. Based on an increase of salinity at the end of the dry season, a present-day seawater intrusion is identified in the surficial Boa Viagem aquifer. Our conceptual model presents a comprehensive understanding of the major groundwater salinization pathways and processes, and should be of benefit for other southern Atlantic coastal aquifers to better address groundwater management issues

Susceptibility to saline contamination of coastal confined aquifer of the Uraba banana axis with hydrogeochemical and isotopic techniques

International Nuclear Information System (INIS)

Paredes Zuniga, Vanessa

2010-01-01

The project has covered an area of study of 8916 km 2 is located in the Northwestern part of the Department of Antioquia, Colombia. Interest area is geologically constituted by tertiary sedimentary rocks (T1 and T2) and alluvial deposits (Quaternary). Hydrogeological units, potentially better use of groundwater, have been established for the unit T2 (confined aquifer) and quaternary deposits.) The area has been of 2600 mm/year to 3600 mm/year of average rainfall. The susceptibility to saline contamination has been determined of coastal aquifer of the Uraba banana axis. Hydrochemical and geological information, geophysics, hydraulic and hydrochemical is used improving existing conceptual hydrogeological model. A hydrochemical characterization has been performed to evaluate the processes of salinity in the confined aquifer. The integration of geological information, geophysical and hydrogeological has been methodology used to validate the hydraulic characteristics of the aquifer, its geometry and operation, updating the conceptual hydrogeological model. The use of complementary tools been able to determine and identify processes that may affect natural physico-chemical characteristics of groundwater. The results have showed that salinization processes present in the coastal aquifer of Uraba Banana Axis could be linked to water-rock interaction, to mixtures with water have become saline as a result of transgression - regression processes in the former study. The hydrogeochemical techniques have become a complementary tool to the hydrogeology allowing respond the questions were presented in complex systems, such as the case of coastal aquifers, where sanitation is usually associated with saline intrusion processes and can also be obeying the conjunction with other hydroclimatological and hydrodynamic aspects. (author) [es

Hydrogeologic setting and ground water flow beneath a section of Indian River Bay, Delaware

Science.gov (United States)

Krantz, David E.; Manheim, Frank T.; Bratton, John F.; Phelan, Daniel J.

2004-01-01

The small bays along the Atlantic coast of the Delmarva Peninsula (Delaware, Maryland, and Virginia) are a valuable natural resource, and an asset for commerce and recreation. These coastal bays also are vulnerable to eutrophication from the input of excess nutrients derived from agriculture and other human activities in the watersheds. Ground water discharge may be an appreciable source of fresh water and a transport pathway for nutrients entering the bays. This paper presents results from an investigation of the physical properties of the surficial aquifer and the processes associated with ground water flow beneath Indian River Bay, Delaware. A key aspect of the project was the deployment of a new technology, streaming horizontal resistivity, to map the subsurface distribution of fresh and saline ground water beneath the bay. The resistivity profiles showed complex patterns of ground water flow, modes of mixing, and submarine ground water discharge. Cores, gamma and electromagnetic-induction logs, and in situ ground water samples collected during a coring operation in Indian River Bay verified the interpretation of the resistivity profiles. The shore-parallel resistivity lines show subsurface zones of fresh ground water alternating with zones dominated by the flow of salt water from the estuary down into the aquifer. Advective flow produces plumes of fresh ground water 400 to 600 m wide and 20 m thick that may extend more than 1 km beneath the estuary. Zones of dispersive mixing between fresh and saline ground water develop on the upper, lower, and lateral boundaries of the the plume. the plumes generally underlie small incised valleys that can be traced landward to stream draining the upland. The incised valleys are filled with 1 to 2 m of silt and peat that act as a semiconfining layer to restrict the downward flow of salt water from the estuary. Active circulation of both the fresh and saline ground water masses beneath the bay is inferred from the geophysical

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

Science.gov (United States)

Li, Q.; Zhan, Y., , Dr; Chen, W. Ms; Yu, S., , Dr

2017-12-01

Salinization in coastal aquifers usually is the results of contamination related to both seawater intrusion and water-rock interaction. The chemical and isotopic methods were combined to identify the origin and processes of groundwater salinization in Daguansha area of Beihai. The concentrations of the major ions that dominate in sea water (Cl-, Na+, Ca2+, Mg2+ and SO2- 4), as well as the isotopic ratios (2H, 18O, 87Sr/86Sr and 13C) suggest that the salinization occurring in the aquifer water of the coastal plain is related to seawater and the prevailing hydrochemical processes are evaporation, mixing, dissolution and ion exchange. For the unconfined aquifer, groundwater salinization occurred in parts of the area, which is significantly influenced by the land-based sea farming. The integrated impacts of seawater intrusion from the Beibuwan Gulf and infiltration of seawater from the culture ponds is identified in the confined aquifer I at site BBW2. In consequence, the leakage from this polluted aquifer causes the salinization of groundwater in the confined aquifer II. At site BBW3, the confined aquifer I and lower confined aquifer II are remarkably contaminated by seawater intrusion. The weak connectivity with upper aquifers and seaward movement of freshwater prevents saltwater from encroaching the confined aquifer III. Above all, understanding of the origin and processes of groundwater salinization will provide essential information for sustainable planning and management of groundwater resources in this region.

Impact of Variable-Density Flow on the Value-of-Information from Pressure and Concentration Data for Saline Aquifer Characterization

Science.gov (United States)

Yoon, S.; Williams, J. R.; Juanes, R.; Kang, P. K.

2017-12-01

Managed aquifer recharge (MAR) is becoming an important solution for ensuring sustainable water resources and mitigating saline water intrusion in coastal aquifers. Accurate estimates of hydrogeological parameters in subsurface flow and solute transport models are critical for making predictions and managing aquifer systems. In the presence of a density difference between the injected freshwater and ambient saline groundwater, the pressure field is coupled to the spatial distribution of salinity distribution, and therefore experiences transient changes. The variable-density effects can be quantified by a mixed convection ratio between two characteristic types of convection: free convection due to density contrast, and forced convection due to a hydraulic gradient. We analyze the variable-density effects on the value-of-information of pressure and concentration data for saline aquifer characterization. An ensemble Kalman filter is used to estimate permeability fields by assimilating the data, and the performance of the estimation is analyzed in terms of the accuracy and the uncertainty of estimated permeability fields and the predictability of arrival times of breakthrough curves in a realistic push-pull setting. This study demonstrates that: 1. Injecting fluids with the velocity that balances the two characteristic convections maximizes the value of data for saline aquifer characterization; 2. The variable-density effects on the value of data for the inverse estimation decrease as the permeability heterogeneity increases; 3. The advantage of joint inversion of pressure and concentration data decreases as the coupling effects between flow and transport increase.

Origin of water salinity in the coastal Sarafand aquifer (South-Lebanon)

International Nuclear Information System (INIS)

Hashash, Adnan; Aranyossy, J.F.

1996-01-01

Author.The geochemical and isotopic study, based on the analysis of twenty water samples from well in the coastal plain of Sarafand (South-Lebanon), permit to eliminate the hypothesis of marine intrusion in this aquifer. The increase of salinity observed in certain wells is due to the contamination of cretaceous aquifer water by the quaternary formations. The two poles of mixing are respectively characterized: by weak tritium contents (between 2 and 3 UT) and a value of stable isotopes (-5,9<0,18<-5,5) corresponding to the appearance of cretaceous formation area; by the high tritium contents and enrichment relative to heavy isotope in the mineralized water of superficial formations. On the other hand, the isotope contents permit the set a rapid renewal of the cretaceous aquifer water due to quick circulation in the Karstic system

A New Method to Infer Advancement of Saline Front in Coastal Groundwater Systems by 3D: The Case of Bari (Southern Italy Fractured Aquifer

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Costantino Masciopinto

2016-02-01

Full Text Available A new method to study 3D saline front advancement in coastal fractured aquifers has been presented. Field groundwater salinity was measured in boreholes of the Bari (Southern Italy coastal aquifer with depth below water table. Then, the Ghyben-Herzberg freshwater/saltwater (50% sharp interface and saline front position were determined by model simulations of the freshwater flow in groundwater. Afterward, the best-fit procedure between groundwater salinity measurements, at assigned water depth of 1.0 m in boreholes, and distances of each borehole from the modelled freshwater/saltwater saline front was used to convert each position (x, y in groundwater to the water salinity concentration at depth of 1.0 m. Moreover, a second best-fit procedure was applied to the salinity measurements in boreholes with depth z. These results provided a grid file (x, y, z, salinity suitable for plotting the actual Bari aquifer salinity by 3D maps. Subsequently, in order to assess effects of pumping on the saltwater-freshwater transition zone in the coastal aquifer, the Navier-Stokes (N-S equations were applied to study transient density-driven flow and salt mass transport into freshwater of a single fracture. The rate of seawater/freshwater interface advancement given by the N-S solution was used to define the progression of saline front in Bari groundwater, starting from the actual salinity 3D map. The impact of pumping of 335 L·s−1 during the transition period of 112.8 days was easily highlighted on 3D salinity maps of Bari aquifer.

Salinity sources of Kefar Uriya wells in the Judea Group aquifer of Israel. Part 1—conceptual hydrogeological model

Science.gov (United States)

Avisar, D.; Rosenthal, E.; Flexer, A.; Shulman, H.; Ben-Avraham, Z.; Guttman, J.

2003-01-01

In the Yarkon-Taninim groundwater basin, the karstic Judea Group aquifer contains groundwater of high quality. However, in the western wells of the Kefar Uriya area located in the foothills of the Judea Mountains, brackish groundwater was locally encountered. The salinity of this water is caused presumably by two end members designated as the 'Hazerim' and 'Lakhish' water types. The Hazerim type represents surface water percolating through a highly fractured thin chalky limestone formation overlying the Judea Group aquifer. The salinity of the water derives conjointly from several sources such as leachates from rendzina and grumosols, dissolution of caliche crusts which contain evaporites and of rock debris from the surrounding formations. This surface water percolates downwards into the aquifer through a funnel- or chimney-like mechanism. This local salinization mechanism supercedes another regional process caused by the Lakhish waters. These are essentially diluted brines originating from deep formations in the western parts of the Coastal Plain. The study results show that salinization is not caused by the thick chalky beds of the Senonian Mt Scopus Group overlying the Judea Group aquifer, as traditionally considered but prevalently by aqueous leachates from soils and rock debris. The conceptual qualitative hydrogeological model of the salinization as demonstrated in this study, is supported by a quantitative hydrological model presented in another paper in this volume.

Salting it away : Saskatchewan's Petroleum Technology Research Centre is leading the study of storing CO{sub 2} in saline aquifers

Energy Technology Data Exchange (ETDEWEB)

Collison, M.

2008-10-15

This paper discussed the 5-year Aquistore project that is being conducted to assess the feasibility of continuously injecting carbon dioxide (CO{sub 2}) into saline aquifers. Conducted by the Petroleum Technology Research Centre (PTRC), the aim of the project is to develop the monitoring technologies needed to prove that the CO{sub 2} can be safely and permanently stored. The $100 million dollar project will also develop technologies needed to build the necessary infrastructure for transporting the CO{sub 2} to the aquifers. Saline aquifers contain more than 10 times the capacity of depleted oil reservoirs. It is estimated that saline aquifers in the Western Canadian Sedimentary Basin (WCSB) contain enough capacity to absorb all reported emissions in Alberta and Saskatchewan every year for the next 1000 years. CO{sub 2} injected into the aquifers will become a supercritical fluid as a result of pressure and temperature forces within the aquifer and will subsequently mineralize and remain there permanently. A dedicated pipeline will transport CO{sub 2} from a refinery in Regina to the aquifer. The project is being funded by Sustainable Development Technology Canada (SDTC), an agency whose mandate is to accelerate the entry of promising energy conservation technologies into the Canadian marketplace. It is hoped that the project will develop saline storage technologies that can be used to promote carbon sequestration in Canada. 5 figs.

Characterization of saline groundwater across the coastal aquifer of Israel as resource for desalination

Science.gov (United States)

Stein, Shaked; Russak, Amos; Sivan, Orit; Yechieli, Yospeh; Oren, Yoram; Kasher, Roni

2015-04-01

In arid countries with access to marine water seawater desalination is becoming an important water source in order to deal with the water scarcity and population growth. Seawater reverse osmosis (RO) facilities use open seawater intake, which requires pretreatment processes to remove particles in order to avoid fouling of the RO membrane. In small and medium size desalination facilities, an alternative water source can be saline groundwater in coastal aquifers. Using saline groundwater from boreholes near the shore as feed water may have the advantage of natural filtration and low organic content. It will also reduce operation costs of pretreatment. Another advantage of using groundwater is its availability in highly populated areas, where planning of large RO desalination plants is difficult and expensive due to real-estate prices. Pumping saline groundwater underneath the freshwater-seawater interface (FSI) might shift the interface towards the sea, thus rehabilitating the fresh water reservoirs in the aquifer. In this research, we tested the potential use of saline groundwater in the coastal aquifer of Israel as feed water for desalination using field work and desalination experiments. Specifically, we sampled the groundwater from a pumping well 100 m from the shore of Tel-Aviv and sea water from the desalination plant in Ashqelon, Israel. We used an RO cross flow system in a pilot plant in order to compare between the two water types in terms of permeate flux, permeate flux decline, salt rejection of the membrane and the fouling on the membrane. The feed, brine and fresh desalinated water from the outlet of the desalination system were chemically analyzed and compared. Field measurements of dissolved oxygen, temperature, pH and salinity were also conducted in situ. Additionally, SDI (silt density index), which is an important index for desalination, and total organic carbon that has a key role in organic fouling and development of biofouling, were measured and

Core drilling provides information about Santa Fe Group aquifer system beneath Albuquerque's West Mesa

Science.gov (United States)

Allen, B.D.; Connell, S.D.; Hawley, J.W.; Stone, B.D.

1998-01-01

Core samples from the upper ???1500 ft of the Santa Fe Group in the Albuquerque West Mesa area provide a first-hand look at the sediments and at subsurface stratigraphic relationships in this important part of the basin-fill aquifer system. Two major hydrostratigraphic subunits consisting of a lower coarse-grained, sandy interval and an overlying fine-grained, interbedded silty sand and clay interval lie beneath the water table at the 98th St core hole. Borehole electrical conductivity measurements reproduce major textural changes observed in the recovered cores and support subsurface correlations of hydrostratigraphic units in the Santa Fe Group aquifer system based on geophysical logs. Comparison of electrical logs from the core hole and from nearby city wells reveals laterally consistent lithostratigraphic patterns over much of the metropolitan area west of the Rio Grande that may be used to delineate structural and related stratigraphic features that have a direct bearing on the availability of ground water.

Fluid Dynamics of Carbon Dioxide Disposal into Saline Aquifers

Energy Technology Data Exchange (ETDEWEB)

Garcia, Julio Enrique [Univ. of California, Berkeley, CA (United States)

2003-01-01

Injection of carbon dioxide (CO₂) into saline aquifers has been proposed as a means to reduce greenhouse gas emissions (geological carbon sequestration). Large-scale injection of CO₂ will induce a variety of coupled physical and chemical processes, including multiphase fluid flow, fluid pressurization and changes in effective stress, solute transport, and chemical reactions between fluids and formation minerals. This work addresses some of these issues with special emphasis given to the physics of fluid flow in brine formations. An investigation of the thermophysical properties of pure carbon dioxide, water and aqueous solutions of CO₂ and NaCl has been conducted. As a result, accurate representations and models for predicting the overall thermophysical behavior of the system CO₂-H₂O-NaCl are proposed and incorporated into the numerical simulator TOUGH2/ECO2. The basic problem of CO₂ injection into a radially symmetric brine aquifer is used to validate the results of TOUGH2/ECO2. The numerical simulator has been applied to more complex flow problem including the CO₂ injection project at the Sleipner Vest Field in the Norwegian sector of the North Sea and the evaluation of fluid flow dynamics effects of CO₂ injection into aquifers. Numerical simulation results show that the transport at Sleipner is dominated by buoyancy effects and that shale layers control vertical migration of CO₂. These results are in good qualitative agreement with time lapse surveys performed at the site. High-resolution numerical simulation experiments have been conducted to study the onset of instabilities (viscous fingering) during injection of CO₂ into saline aquifers. The injection process can be classified as immiscible displacement of an aqueous phase by a less dense and less viscous gas phase. Under disposal conditions (supercritical CO₂) the viscosity of carbon

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

LASTRIG -A Multiple Parametric Method of Assessment of Salinization Vulnerability of a Coastal Aquifer in Pennar Delta, India

Science.gov (United States)

Kesireddy, K.; Mareddy, A.

2007-05-01

Coastal populations are critically dependent upon the coastal aquifers for their freshwater requirements. Excessive withdrawal of groundwater leads to saline incursion and the consequent degradation of quality and quantity of freshwater. The paper describes a multiple parametric method of assessment of vulnerability of the coastal aquifer in Pennar delta, south India, in the context of the hydrogeological, biophysical, geochemical and socioeconomic environments of the delta. Seven parameters, forming the acronym LASTRIG viz. landuse, aquifer type, soil depth, groundwater table, rainfall, soil infiltration and geomorphology are made use in the assessment, and involve the use of remote sensing, GIS and modeling tools. The parameters are weighted, and a suitable ranking system has been designed to quantify the degree of vulnerability of the aquifer for salinization. It has been found that zones with high vulnerability index correlate well with zones of high TDS and chloride contents of groundwater. This observation thus validates the geochemical basis of the proposed LASTRIG system. The new system has been found useful in the management of the groundwater resources of the delta region. It has been made use of identify the aquifer segments which are in danger of being degraded, to enable the decision- makers to design counter measures to avoid further deterioration in water quality. Where the groundwater has already been rendered non-potable because of saline incursion, the LASTRIG index could be made use to identify possible use of that water for drinking by cattle, and for growing of salt-tolerant vegetables (e.g. beetroot and lettuce), and trees (e.g. casuarinas obese, Prosopis juliflora)

The Impacts of Soil Fertility and Salinity on Soil Nitrogen Dynamics Mediated by the Soil Microbial Community Beneath the Halophytic Shrub Tamarisk.

Science.gov (United States)

Iwaoka, Chikae; Imada, Shogo; Taniguchi, Takeshi; Du, Sheng; Yamanaka, Norikazu; Tateno, Ryunosuke

2018-05-01

Nitrogen (N) is one of the most common limiting nutrients for primary production in terrestrial ecosystems. Soil microbes transform organic N into inorganic N, which is available to plants, but soil microbe activity in drylands is sometimes critically suppressed by environmental factors, such as low soil substrate availability or high salinity. Tamarisk (Tamarix spp.) is a halophytic shrub species that is widely distributed in the drylands of China; it produces litter enriched in nutrients and salts that are thought to increase soil fertility and salinity under its crown. To elucidate the effects of tamarisks on the soil microbial community, and thus N dynamics, by creating "islands of fertility" and "islands of salinity," we collected soil samples from under tamarisk crowns and adjacent barren areas at three habitats in the summer and fall. We analyzed soil physicochemical properties, inorganic N dynamics, and prokaryotic community abundance and composition. In soils sampled beneath tamarisks, the N mineralization rate was significantly higher, and the prokaryotic community structure was significantly different, from soils sampled in barren areas, irrespective of site and season. Tamarisks provided suitable nutrient conditions for one of the important decomposers in the area, Verrucomicrobia, by creating "islands of fertility," but provided unsuitable salinity conditions for other important decomposers, Flavobacteria, Gammaproteobacteria, and Deltaproteobacteria, by mitigating salt accumulation. However, the quantity of these decomposers tended to be higher beneath tamarisks, because they were relatively unaffected by the small salinity gradient created by the tamarisks, which may explain the higher N mineralization rate beneath tamarisks.

CO2 storage in saline aquifers: In the Southern North Sea and Northern Germany

NARCIS (Netherlands)

Weijer, V. van de; Meer, B. van der; Kramers, L.; Neele, F.; Maurand, N.; Gallo, Y. le; Bossie-Codré, D.; Schäfer, F.; Evans, D.; Kirk, K.; Bernstone, C.; Stiff, S.; Hull, W.

2009-01-01

CO2 storage in depleted gas fields is attractive but gas fields are unequally distributed geographically and can be utilized only within a restricted window of opportunity. Therefore, CO2 storage in saline aquifers can be expected to become an important element of CO2 capture and storage (CCS)

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

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.

Mapping deep aquifer salinity trends in the southern San Joaquin Valley using borehole geophysical data constrained by chemical analyses

Science.gov (United States)

Gillespie, J.; Shimabukuro, D.; Stephens, M.; Chang, W. H.; Ball, L. B.; Everett, R.; Metzger, L.; Landon, M. K.

2016-12-01

The California State Water Resources Control Board and the California Division of Oil, Gas and Geothermal Resources are collaborating with the U.S. Geological Survey to map groundwater resources near oil fields and to assess potential interactions between oil and gas development and groundwater resources. Groundwater resources having salinity less than 10,000 mg/L total dissolved solids may be classified as Underground Sources of Drinking Water (USDW) and subject to protection under the federal Safe Drinking Water Act. In this study, we use information from oil well borehole geophysical logs, oilfield produced water and groundwater chemistry data, and three-dimensional geologic surfaces to map the spatial distribution of salinity in aquifers near oil fields. Salinity in the southern San Joaquin Valley is controlled primarily by depth and location. The base of protected waters occurs at very shallow depths, often 1,500 meters, in the eastern part of the San Joaquin Valley where higher runoff from the western slopes of the Sierra Nevada provide relatively abundant aquifer recharge. Stratigraphy acts as a secondary control on salinity within these broader areas. Formations deposited in non-marine environments are generally fresher than marine deposits. Layers isolated vertically between confining beds and cut off from recharge sources may be more saline than underlying aquifers that outcrop in upland areas on the edge of the valley with more direct connection to regional recharge areas. The role of faulting is more ambiguous. In some areas, abrupt changes in salinity may be fault controlled but, more commonly, the faults serve as traps separating oil-bearing strata that are exempt from USDW regulations, from water-bearing strata that are not exempt.

Fate of effluent-borne contaminants beneath septic tank drainfields overlying a Karst aquifer.

Science.gov (United States)

Katz, Brian G; Griffin, Dale W; McMahon, Peter B; Harden, Harmon S; Wade, Edgar; Hicks, Richard W; Chanton, Jeffrey P

2010-01-01

Groundwater quality effects from septic tanks were investigated in the Woodville Karst Plain, an area that contains numerous sinkholes and a thin veneer of sands and clays overlying the Upper Floridan aquifer (UFA). Concerns have emerged about elevated nitrate concentrations in the UFA, which is the source of water supply in this area of northern Florida. At three sites during dry and wet periods in 2007-2008, water samples were collected from the septic tank, shallow and deep lysimeters, and drainfield and background wells in the UFA and analyzed for multiple chemical indicators including nutrients, nitrate isotopes, organic wastewater compounds (OWCs), pharmaceutical compounds, and microbiological indicators (bacteria and viruses). Median NO3-N concentration in groundwater beneath the septic tank drainfields was 20 mg L(-1) (8.0-26 mg L(-1)). After adjusting for dilution, about 25 to 40% N loss (from denitrification, ammonium sorption, and ammonia volatilization) occurs as septic tank effluent moves through the unsaturated zone to the water table. Nitrogen loading rates to groundwater were highly variable at each site (3.9-12 kg N yr(-1)), as were N and chloride depth profiles in the unsaturated zone. Most OWCs and pharmaceutical compounds were highly attenuated beneath the drainfields; however, five Cs (caffeine, 1,7-dimethylxanthine, phenol, galaxolide, and tris(dichloroisotopropyl)phosphate) and two pharmaceutical compounds (acetaminophen and sulfamethoxazole) were detected in groundwater samples. Indicator bacteria and human enteric viruses were detected in septic tank effluent samples but only intermittently in soil water and groundwater. Contaminant movement to groundwater beneath each septic tank system also was related to water use and differences in lithology at each site.

Potential effects of alterations to the hydrologic system on the distribution of salinity in the Biscayne aquifer in Broward County, Florida

Science.gov (United States)

Hughes, Joseph D.; Sifuentes, Dorothy F.; White, Jeremy T.

2016-03-15

To address concerns about the effects of water-resource management practices and rising sea level on saltwater intrusion, the U.S. Geological Survey in cooperation with the Broward County Environmental Planning and Community Resilience Division, initiated a study to examine causes of saltwater intrusion and predict the effects of future alterations to the hydrologic system on salinity distribution in eastern Broward County, Florida. A three-dimensional, variable-density solute-transport model was calibrated to conditions from 1970 to 2012, the period for which data are most complete and reliable, and was used to simulate historical conditions from 1950 to 2012. These types of models are typically difficult to calibrate by matching to observed groundwater salinities because of spatial variability in aquifer properties that are unknown, and natural and anthropogenic processes that are complex and unknown; therefore, the primary goal was to reproduce major trends and locally generalized distributions of salinity in the Biscayne aquifer. The methods used in this study are relatively new, and results will provide transferable techniques for protecting groundwater resources and maximizing groundwater availability in coastal areas. The model was used to (1) evaluate the sensitivity of the salinity distribution in groundwater to sea-level rise and groundwater pumping, and (2) simulate the potential effects of increases in pumping, variable rates of sea-level rise, movement of a salinity control structure, and use of drainage recharge wells on the future distribution of salinity in the aquifer.

Coastal groundwater salinization: Focus on the vertical variability in a multi-layered aquifer through a multi-isotope fingerprinting (Roussillon Basin, France)

Energy Technology Data Exchange (ETDEWEB)

Petelet-Giraud, Emmanuelle, E-mail: e.petelet@brgm.fr [BRGM, Avenue C. Guillemin, BP 36009, 45060 Orléans Cedex 02 (France); Négrel, Philippe [BRGM, Avenue C. Guillemin, BP 36009, 45060 Orléans Cedex 02 (France); Aunay, Bertrand [BRGM, Réunion Agency, 5, rue Sainte-Anne, CS 51016, 97404 Saint Denis Cedex (France); Ladouche, Bernard; Bailly-Comte, Vincent [BRGM Montpellier Agency, 1039, rue de Pinville, 34000 Montpellier (France); Guerrot, Catherine; Flehoc, Christine [BRGM, Avenue C. Guillemin, BP 36009, 45060 Orléans Cedex 02 (France); Pezard, Philippe; Lofi, Johanna [Géosciences Montpellier, UMR 5243, Université de Montpellier, cc069, Place Eugène Bataillon, 34095 Montpellier Cedex 05 (France); Dörfliger, Nathalie [BRGM, Avenue C. Guillemin, BP 36009, 45060 Orléans Cedex 02 (France)

2016-10-01

The Roussillon sedimentary Basin (South France) is a complex multi-layered aquifer, close to the Mediterranean Sea facing seasonally increases of water abstraction and salinization issues. We report geochemical and isotopic vertical variability in this aquifer using groundwater sampled with a Westbay System® at two coastal monitoring sites: Barcarès and Canet. The Westbay sampling allows pointing out and explaining the variation of water quality along vertical profiles, both in productive layers and in the less permeable ones where most of the chemical processes are susceptible to take place. The aquifer layers are not equally impacted by salinization, with electrical conductivity ranging from 460 to 43,000 μS·cm{sup −1}. The δ{sup 2}H–δ{sup 18}O signatures show mixing between seawater and freshwater components with long water residence time as evidenced by the lack of contribution from modern water using {sup 3}H, {sup 14}C and CFCs/SF6. S(SO{sub 4}) isotopes also evidence seawater contribution but some signatures can be related to oxidation of pyrite and/or organically bounded S. In the upper layers {sup 87}Sr/{sup 86}Sr ratios are close to that of seawater and then increase with depth, reflecting water–rock interaction with argillaceous formations while punctual low values reflect interaction with carbonate. Boron isotopes highlight secondary processes such as adsorption/desorption onto clays in addition to mixings. At the Barcarès site (120 m deep), the high salinity in some layers appear to be related neither to present day seawater intrusion, nor to Salses-Leucate lagoonwater intrusion. Groundwater chemical composition thus highlights binary mixing between fresh groundwater and inherited salty water together with cation exchange processes, water–rock interactions and, locally, sedimentary organic matter mineralisation probably enhanced by pyrite oxidation. Finally, combining the results of this study and those of Caballero and Ladouche (2015

Tackling the salinity-pollution nexus in coastal aquifers from arid regions using nitrate and boron isotopes.

Science.gov (United States)

Re, V; Sacchi, E

2017-05-01

Salinization and nitrate pollution are generally ascertained as the main issues affecting coastal aquifers worldwide. In arid zones, where agricultural activities also result in soil salinization, both phenomena tend to co-exist and synergically contribute to alter groundwater quality, with severe negative impacts on human populations and natural ecosystems' wellbeing. It becomes therefore necessary to understand if and to what extent integrated hydrogeochemical tools can help in distinguishing among possible different salinization and nitrate contamination origins, in order to provide adequate science-based support to local development and environmental protection. The alluvial plain of Bou-Areg (North Morocco) extends over about 190 km 2 and is separated from the Mediterranean Sea by the coastal Lagoon of Nador. Its surface is covered for more than 60% by agricultural activities, although the region has been recently concerned by urban population increase and tourism expansion. All these activities mainly rely on groundwater exploitation and at the same time are the main causes of both aquifer and lagoon water quality degradation. For this reason, it was chosen as a case study representative of the typical situation of coastal aquifers in arid zones worldwide, where a clear identification of salinization and pollution sources is fundamental for the implementation of locally oriented remedies and long-term management strategies. Results of a hydrogeochemical investigation performed between 2009 and 2011 show that the Bou-Areg aquifer presents high salinity (often exceeding 100 mg/L in TDS) due to both natural and anthropogenic processes. The area is also impacted by nitrate contamination, with concentrations generally exceeding the WHO statutory limits for drinking water (50 mg/L) and reaching up to about 300 mg/L, in both the rural and urban/peri-urban areas. The isotopic composition of dissolved nitrates (δ 15 N NO3 and δ 18 O NO ) was used to constrain

Fingerprinting groundwater salinity sources in the Gulf Coast Aquifer System, USA

Science.gov (United States)

Chowdhury, Ali H.; Scanlon, Bridget R.; Reedy, Robert C.; Young, Steve

2018-02-01

Understanding groundwater salinity sources in the Gulf Coast Aquifer System (GCAS) is a critical issue due to depletion of fresh groundwater and concerns for potential seawater intrusion. The study objective was to assess sources of groundwater salinity in the GCAS using ˜1,400 chemical analyses and ˜90 isotopic analyses along nine well transects in the Texas Gulf Coast, USA. Salinity increases from northeast (median total dissolved solids (TDS) 340 mg/L) to southwest (median TDS 1,160 mg/L), which inversely correlates with the precipitation distribution pattern (1,370- 600 mm/yr, respectively). Molar Cl/Br ratios (median 540-600), depleted δ2H and δ18O (-24.7‰, -4.5‰) relative to seawater (Cl/Br ˜655 and δ2H, δ18O 0‰, 0‰, respectively), and elevated 36Cl/Cl ratios (˜100), suggest precipitation enriched with marine aerosols as the dominant salinity source. Mass balance estimates suggest that marine aerosols could adequately explain salt loading over the large expanse of the GCAS. Evapotranspiration enrichment to the southwest is supported by elevated chloride concentrations in soil profiles and higher δ18O. Secondary salinity sources include dissolution of salt domes or upwelling brines from geopressured zones along growth faults, mainly near the coast in the northeast. The regional extent and large quantities of brackish water have the potential to support moderate-sized desalination plants in this location. These results have important implications for groundwater management, suggesting a current lack of regional seawater intrusion and a suitable source of relatively low TDS water for desalination.

Baseline mapping study of the Steed Pond aquifer and vadose zone beneath A/M Area, Savannah River Site, Aiken, South Carolina

International Nuclear Information System (INIS)

Jackson, D.G. Jr.

2000-01-01

This report presents the second phase of a baseline mapping project conducted for the Environmental Restoration Department (ERD) at Savannah River Site. The purpose of this second phase is to map the structure and distribution of mud (clay and silt-sized sediment) within the vadose zone beneath A/M Area. The results presented in this report will assist future characterization and remediation activities in the vadose zone and upper aquifer zones in A/M Area

Summary of northern Atlantic coastal plain hydrology and its relation to disposal of high-level radioactive waste in buried crystalline rock; a preliminary appraisal

Science.gov (United States)

Lloyd, O.B.; Larson, J.D.; Davis, R.W.

1985-01-01

Interpretation of available hydrologic data suggests that some areas beneath the Coastal Plain in the States of Delaware, Maryland, New Jersey, North Carolina, and Virginia might have some potential for the disposal of nuclear waste in crystalline rock that is buried beneath the Coastal Plain sediments. The areas of major interest occur where the top of the basement rock lies between 1,000 and 4,000 feet below sea level, the aquifer(s) immediately above the basement rock are saturated with saline water, confining material overlies the saline water bearing aquifer(s), and groundwater flow in the saline water aquifer(s) can be established. Preliminary data on (1) the distribution and thickness of the lowermost aquifers and confining beds, (2) the distribution of hydraulic conductivity in the lowermost aquifers, (3) estimated hydraulic heads and inferred direction of lateral groundwater flow for 1980, and (4) the distribution of saline water and brine, indicate eastern parts of the study area relatively best meet most of the criteria proposed for sediments that would overlie any potential buried crystalline-rock disposal site.

Potential effects of deepening the St. Johns River navigation channel on saltwater intrusion in the surficial aquifer system, Jacksonville, Florida

Science.gov (United States)

Bellino, Jason C.; Spechler, Rick M.

2013-01-01

section near River Mile 8. Salinity increases of up to 4.0 parts per thousand (ppt) were indicated by the model incorporating hydrogeologic conceptualizations with both a semiconfining bed over the limestone unit and a preferential flow layer within the limestone along the cross section near River Mile 8. Simulated increases in salinity greater than 0.2 ppt in this area were generally limited to portions of the limestone unit within about 75 feet of the channel on the north side of the river. The potential for saltwater to move from the river channel to the surficial aquifer system is limited, but may be present in areas where the head gradient from the aquifer to the river is small or negative and the salinity of the river is sufficient to induce density-driven advective flow into the aquifer. In some areas, simulated increases in salinity were exacerbated by the presence of laterally extensive semiconfining beds in combination with a high-conductivity preferential flow zone in the limestone unit of the surficial aquifer system and an upgradient source of saline water, such as beneath the salt marshes near Fanning Island. The volume of groundwater pumped in these areas is estimated to be low; therefore, saltwater intrusion will not substantially affect regional water supply, although users of the surficial aquifer system east of Dames Point along the northern shore of the river could be affected. Proposed dredging operations pose no risk to salinization of the Floridan aquifer system; in the study area, the intermediate confining unit ranges in thickness from more than 300 to about 500 feet and provides sufficient hydraulic separation between the surficial and Floridan aquifer systems.

Geologic CO2 Sequestration: Predicting and Confirming Performance in Oil Reservoirs and Saline Aquifers

Science.gov (United States)

Johnson, J. W.; Nitao, J. J.; Newmark, R. L.; Kirkendall, B. A.; Nimz, G. J.; Knauss, K. G.; Ziagos, J. P.

2002-05-01

Reducing anthropogenic CO2 emissions ranks high among the grand scientific challenges of this century. In the near-term, significant reductions can only be achieved through innovative sequestration strategies that prevent atmospheric release of large-scale CO2 waste streams. Among such strategies, injection into confined geologic formations represents arguably the most promising alternative; and among potential geologic storage sites, oil reservoirs and saline aquifers represent the most attractive targets. Oil reservoirs offer a unique "win-win" approach because CO2 flooding is an effective technique of enhanced oil recovery (EOR), while saline aquifers offer immense storage capacity and widespread distribution. Although CO2-flood EOR has been widely used in the Permian Basin and elsewhere since the 1980s, the oil industry has just recently become concerned with the significant fraction of injected CO2 that eludes recycling and is therefore sequestered. This "lost" CO2 now has potential economic value in the growing emissions credit market; hence, the industry's emerging interest in recasting CO2 floods as co-optimized EOR/sequestration projects. The world's first saline aquifer storage project was also catalyzed in part by economics: Norway's newly imposed atmospheric emissions tax, which spurred development of Statoil's unique North Sea Sleipner facility in 1996. Successful implementation of geologic sequestration projects hinges on development of advanced predictive models and a diverse set of remote sensing, in situ sampling, and experimental techniques. The models are needed to design and forecast long-term sequestration performance; the monitoring techniques are required to confirm and refine model predictions and to ensure compliance with environmental regulations. We have developed a unique reactive transport modeling capability for predicting sequestration performance in saline aquifers, and used it to simulate CO2 injection at Sleipner; we are now

Integrating an artificial intelligence approach with k-means clustering to model groundwater salinity: the case of Gaza coastal aquifer (Palestine)

Science.gov (United States)

Alagha, Jawad S.; Seyam, Mohammed; Md Said, Md Azlin; Mogheir, Yunes

2017-12-01

Artificial intelligence (AI) techniques have increasingly become efficient alternative modeling tools in the water resources field, particularly when the modeled process is influenced by complex and interrelated variables. In this study, two AI techniques—artificial neural networks (ANNs) and support vector machine (SVM)—were employed to achieve deeper understanding of the salinization process (represented by chloride concentration) in complex coastal aquifers influenced by various salinity sources. Both models were trained using 11 years of groundwater quality data from 22 municipal wells in Khan Younis Governorate, Gaza, Palestine. Both techniques showed satisfactory prediction performance, where the mean absolute percentage error (MAPE) and correlation coefficient ( R) for the test data set were, respectively, about 4.5 and 99.8% for the ANNs model, and 4.6 and 99.7% for SVM model. The performances of the developed models were further noticeably improved through preprocessing the wells data set using a k-means clustering method, then conducting AI techniques separately for each cluster. The developed models with clustered data were associated with higher performance, easiness and simplicity. They can be employed as an analytical tool to investigate the influence of input variables on coastal aquifer salinity, which is of great importance for understanding salinization processes, leading to more effective water-resources-related planning and decision making.

Tracing groundwater salinization processes in coastal aquifers: a hydrogeochemical and isotopic approach in the Na-Cl brackish waters of northwestern Sardinia, Italy

Directory of Open Access Journals (Sweden)

G. Mongelli

2013-07-01

Full Text Available Throughout the Mediterranean, salinization threatens water quality, especially in coastal areas. This salinization is the result of concomitant processes related to both seawater intrusion and water–rock interaction, which in some cases are virtually indistinguishable. In the Nurra region of northwestern Sardinia, recent salinization related to marine water intrusion has been caused by aquifer exploitation. However, the geology of this region records a long history from the Palaeozoic to the Quaternary, and is structurally complex and comprises a wide variety of lithologies, including Triassic evaporites. Determining the origin of the saline component of the Jurassic and Triassic aquifers in the Nurra region may provide a useful and more general model for salinization processes in the Mediterranean area, where the occurrence of evaporitic rocks in coastal aquifers is a common feature. In addition, due to intensive human activity and recent climatic change, the Nurra has become vulnerable to desertification and, in common with other Mediterranean islands, surface water resources periodically suffer from severe shortages. With this in mind, we report new data regarding brackish and surface waters (outcrop and lake samples of the Na-Cl type from the Nurra region, including major ions and selected trace elements (B, Br, I, and Sr, in addition to isotopic data including δ18O, δD in water, and δ34S and δ18O in dissolved SO4. To identify the origin of the salinity more precisely, we also analysed the mineralogical and isotopic composition of Triassic evaporites. The brackish waters have Cl contents of up to 2025 mg L−1 , and the ratios between dissolved ions and Cl, with the exception of the Br / Cl ratio, are not those expected on the basis of simple mixing between rainwater and seawater. The δ18O and δD data indicate that most of the waters fall between the regional meteoric water line and the global meteoric water line, supporting the

Tracing groundwater salinization processes in coastal aquifers: a hydrogeochemical and isotopic approach in the Na-Cl brackish waters of northwestern Sardinia, Italy

Science.gov (United States)

Mongelli, G.; Monni, S.; Oggiano, G.; Paternoster, M.; Sinisi, R.

2013-07-01

Throughout the Mediterranean, salinization threatens water quality, especially in coastal areas. This salinization is the result of concomitant processes related to both seawater intrusion and water-rock interaction, which in some cases are virtually indistinguishable. In the Nurra region of northwestern Sardinia, recent salinization related to marine water intrusion has been caused by aquifer exploitation. However, the geology of this region records a long history from the Palaeozoic to the Quaternary, and is structurally complex and comprises a wide variety of lithologies, including Triassic evaporites. Determining the origin of the saline component of the Jurassic and Triassic aquifers in the Nurra region may provide a useful and more general model for salinization processes in the Mediterranean area, where the occurrence of evaporitic rocks in coastal aquifers is a common feature. In addition, due to intensive human activity and recent climatic change, the Nurra has become vulnerable to desertification and, in common with other Mediterranean islands, surface water resources periodically suffer from severe shortages. With this in mind, we report new data regarding brackish and surface waters (outcrop and lake samples) of the Na-Cl type from the Nurra region, including major ions and selected trace elements (B, Br, I, and Sr), in addition to isotopic data including δ18O, δD in water, and δ34S and δ18O in dissolved SO4. To identify the origin of the salinity more precisely, we also analysed the mineralogical and isotopic composition of Triassic evaporites. The brackish waters have Cl contents of up to 2025 mg L-1 , and the ratios between dissolved ions and Cl, with the exception of the Br / Cl ratio, are not those expected on the basis of simple mixing between rainwater and seawater. The δ18O and δD data indicate that most of the waters fall between the regional meteoric water line and the global meteoric water line, supporting the conclusion that they are

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.

Global Sensitivity Analysis to Assess Salt Precipitation for CO2 Geological Storage in Deep Saline Aquifers

Directory of Open Access Journals (Sweden)

Yuan Wang

2017-01-01

Full Text Available Salt precipitation is generated near the injection well when dry supercritical carbon dioxide (scCO2 is injected into saline aquifers, and it can seriously impair the CO2 injectivity of the well. We used solid saturation (Ss to map CO2 injectivity. Ss was used as the response variable for the sensitivity analysis, and the input variables included the CO2 injection rate (QCO2, salinity of the aquifer (XNaCl, empirical parameter m, air entry pressure (P0, maximum capillary pressure (Pmax, and liquid residual saturation (Splr and Sclr. Global sensitivity analysis methods, namely, the Morris method and Sobol method, were used. A significant increase in Ss was observed near the injection well, and the results of the two methods were similar: XNaCl had the greatest effect on Ss; the effect of P0 and Pmax on Ss was negligible. On the other hand, with these two methods, QCO2 had various effects on Ss: QCO2 had a large effect on Ss in the Morris method, but it had little effect on Ss in the Sobol method. We also found that a low QCO2 had a profound effect on Ss but that a high QCO2 had almost no effect on the Ss value.

Electrical Conductivity in the Vadose Zone beneath a Tamarisk Grove along the Virgin River in Nevada

Science.gov (United States)

Shillito, R.; Sueki, S.; Berli, M.; Healey, J. M.; Acharya, K.

2013-12-01

Thick tamarisk groves along river corridors of the Southwest can transpire vast quantities of water and, as an invasive species, compete with native plants for space and resources. It is hypothesized that tamarisk can outcompete other species by not only tolerating high soil salinity, but by increasing soil salinity due to transpiration of salt-rich near-surface groundwater. The goal of this study was to garner experimental evidence for salt accumulation around tamarisk trees in comparison with other species (mesquite) along the Virgin River near Riverside, NV. At the experimental site, electrical conductivity (EC), temperature (T), and volumetric water content (VWC) within the vadose zone were monitored using sensors at 20, 40, 60, 80 and 100 cm depth on 30-minute intervals within the tamarisk thicket where several mesquite trees are found. Nearby groundwater levels were monitored every 40 days. The 2012 - 2013 data reveal an unexpected EC profile between the surface and the groundwater table (average depth 100 cm). A crust was found within depressions on the surface with EC values as high as 18.8 mS/cm. In the vadose zone (0 to 80 cm depth), average EC values of 4.4 mS/cm were recorded. Most interestingly, in the capillary fringe immediately above the water table (80 to 100 cm depth) average EC values of only 1.25 mS/cm were found whereas the groundwater (>100 cm depth) showed considerably higher EC values averaging 8.8 mS/cm. Additionally, the surface beneath the tamarisk had double the EC as that beneath the mesquite. The contrast in the EC indicates an increase in the aquifer salinity, which may be due to leachate infiltration through the vadose zone concentrated by plant transpiration and direct deposition of saline tamarisk leaf litter and secretions onto the understory. Evapotranspiration and shedding of litter by the tamarisk accelerated the salinity concentrations in the uppermost part of the vadose zone. Ultimately, understanding the salinity regime as

Investigating the salinization and freshening processes of coastal groundwater resources in Urmia aquifer, NW Iran.

Science.gov (United States)

Amiri, Vahab; Nakhaei, Mohammad; Lak, Razyeh; Kholghi, Majid

2016-04-01

This paper presents the results of an assessment about interaction between Urmia Lake (UL) and coastal groundwater in the Urmia aquifer (UA). This aquifer is the most significant contributor to the freshwater supply of the coastal areas. The use of hydrochemical facies can be very useful to identify the saltwater encroachment or freshening phases in the coastal aquifers. In this study, the analysis of salinization/freshening processes was carried out through the saturation index (SI), ionic deltas (Δ), binary diagrams, and hydrochemical facies evolution (HFE) diagram. Based on the Gibbs plot, the behavior of the major ions showed that the changes in the chemical composition of the groundwater are mainly controlled by the water-soil/rock interaction zone and few samples are relatively controlled by evaporation. A possible explanation for this phenomenon is that the deposited chloride and sulfate particles can form the minor salinity source in some coastal areas when washed down by precipitation. The SI calculations showed that all groundwater samples, collected in these periods, show negative saturation indices, which indicate undersaturation with respect to anhydrite, gypsum, and halite. In addition, except in a few cases, all other samples showed the undersaturation with respect to the carbonate minerals such as aragonite, calcite, and dolomite. Therefore, these minerals are susceptible to dissolution. In the dry season, the SI calculations showed more positive values with respect to dolomite, especially in the northern part of UA, which indicated a higher potential for precipitation and deposition of dolomite. The percentage of saltwater in the groundwater samples of Urmia plain was very low, ranging between 0.001 and 0.79 % in the wet season and 0.0004 and 0.81 % in the dry season. The results of HFE diagram, which was taken to find whether the aquifer was in the saltwater encroachment phase or in the freshening phase, indicated that except for a few wells

Numerical Simulation of Borehole Flow in Deep Monitor Wells, Pearl Harbor Aquifer, Oahu, Hawaii

Science.gov (United States)

Rotzoll, K.; Oki, D. S.; El-Kadi, A. I.

2010-12-01

Salinity profiles collected from uncased deep monitor wells are commonly used to monitor freshwater-lens thickness in coastal aquifers. However, vertical flow in these wells can cause the measured salinity to differ from salinity in the adjacent aquifer. Substantial borehole flow has been observed in uncased wells in the Pearl Harbor aquifer, Oahu, Hawaii. A numerical modeling approach, incorporating aquifer hydraulic characteristics and recharge rates representative of the Pearl Harbor aquifer, was used to evaluate the effects of borehole flow on measured salinity profiles from deep monitor wells. Borehole flow caused by vertical hydraulic gradients associated with the natural regional groundwater-flow system and local groundwater withdrawals was simulated. Model results were used to estimate differences between vertical salinity profiles in deep monitor wells and the adjacent aquifer in areas of downward, horizontal, and upward flow within the regional flow system—for cases with and without nearby pumped wells. Aquifer heterogeneity, represented in the model as layers of contrasting permeability, was incorporated in model scenarios. Results from this study provide insight into the magnitude of the differences between vertical salinity profiles from deep monitor wells and the salinity distributions in the aquifers. These insights are relevant and are critically needed for management and predictive modeling purposes.

Use of a time-domain electromagnetic method with geochemical tracers to explore the salinity anomalies in a small coastal aquifer in north-eastern Tunisia

Science.gov (United States)

Chekirbane, Anis; Tsujimura, Maki; Kawachi, Atsushi; Lachaal, Fethi; Isoda, Hiroko; Tarhouni, Jamila

2014-12-01

The study area is a small coastal plain in north-eastern Tunisia. It is drained by an ephemeral stream network and is subject to several pollutant discharges such as oilfield brine coming from a neighboring oil company and wastewater from Somâa city, located in the upstream of the plain. Furthermore, a hydraulic head near the coastal part of the aquifer is below sea level, suggesting that seawater intrusion may occur. A time-domain electromagnetic (TDEM) survey, based on 28 soundings, was conducted in Wadi Al Ayn and Daroufa plains to delineate the saline groundwater. Based on longitudinal and transversal resistivity two-dimensional pseudosections calibrated with boring data, the extent of saline water was identified. Geochemical tracers were combined with the resistivity dataset to differentiate the origin of groundwater salinization. In the upstream part of the plain, the infiltration of oilfield brine through the sandy bed of Wadi Al Ayn seems to have a considerable effect on groundwater salinization. However, in the coastal part of the aquifer, groundwater salinization is due to seawater intrusion and the saltwater is reaching an inland extent around 1.3 km from the shoreline. The contribution ratios of saline water bodies derived from the inverted chloride data vary for the oilfield brine from 1 to 13 % and for the seawater from 2 to 21 %.

The use of salinity contrast for density difference compensation to improve the thermal recovery efficiency in high-temperature aquifer thermal energy storage systems

Science.gov (United States)

van Lopik, Jan H.; Hartog, Niels; Zaadnoordijk, Willem Jan

2016-08-01

The efficiency of heat recovery in high-temperature (>60 °C) aquifer thermal energy storage (HT-ATES) systems is limited due to the buoyancy of the injected hot water. This study investigates the potential to improve the efficiency through compensation of the density difference by increased salinity of the injected hot water for a single injection-recovery well scheme. The proposed method was tested through numerical modeling with SEAWATv4, considering seasonal HT-ATES with four consecutive injection-storage-recovery cycles. Recovery efficiencies for the consecutive cycles were investigated for six cases with three simulated scenarios: (a) regular HT-ATES, (b) HT-ATES with density difference compensation using saline water, and (c) theoretical regular HT-ATES without free thermal convection. For the reference case, in which 80 °C water was injected into a high-permeability aquifer, regular HT-ATES had an efficiency of 0.40 after four consecutive recovery cycles. The density difference compensation method resulted in an efficiency of 0.69, approximating the theoretical case (0.76). Sensitivity analysis showed that the net efficiency increase by using the density difference compensation method instead of regular HT-ATES is greater for higher aquifer hydraulic conductivity, larger temperature difference between injection water and ambient groundwater, smaller injection volume, and larger aquifer thickness. This means that density difference compensation allows the application of HT-ATES in thicker, more permeable aquifers and with larger temperatures than would be considered for regular HT-ATES systems.

Numerical simulation of CO2 geological storage in saline aquifers – case study of Utsira formation

Energy Technology Data Exchange (ETDEWEB)

Zhang, Zheming; Agarwal, Ramesh K. [Department of Mechanical Engineering and Materials Science, Washington University, St. Louis, MO 63130 (United States)

2013-07-01

CO2 geological storage (CGS) is one of the most promising technologies to address the issue of excessive anthropogenic CO2 emissions in the atmosphere due to fossil fuel combustion for electricity generation. In order to fully exploit the storage potential, numerical simulations can help in determining injection strategies before the deployment of full scale sequestration in saline aquifers. This paper presents the numerical simulations of CO2 geological storage in Utsira saline formation where the sequestration is currently underway. The effects of various hydrogeological and numerical factors on the CO2 distribution in the topmost hydrogeological layer of Utsira are discussed. The existence of multiple pathways for upward mobility of CO2 into the topmost layer of Utsira as well as the performance of the top seal are also investigated.

The influence of fish ponds and salinization on groundwater quality in the multi-layer coastal aquifer system in Israel

Science.gov (United States)

Tal, A.; Weinstein, Y.; Yechieli, Y.; Borisover, M.

2017-08-01

This study focuses on the impact of surface reservoirs (fish ponds) on a multi aquifer coastal system, and the relation between the aquifer and the sea. The study was conducted in an Israeli Mediterranean coastal aquifer, which includes a sandy phreatic unit and two confined calcareous sandstone units. The geological description is based on 52 wells, from which 33 samples were collected for stable isotope analysis and 25 samples for organic and inorganic parameters. Hydraulic head and chemical measurements suggest that there is an hydraulic connection between the fish ponds above the aquifer and the phreatic unit, whereas the connection with the confined units is very limited. The phreatic unit is characterized by a low concentration of oxygen and high concentrations of ammonium and phosphate, while the confined units are characterized by higher oxygen and much lower ammonium and phosphate concentrations. Organic matter fluorescence was found to be a tool to distinguish the contribution of the pond waters, whereby a pond water signature (characterized by proteinaceous (tryptophan-like) and typical humic-matter fluorescence) was found in the phreatic aquifer. The phreatic unit is also isotopically enriched, similar to pond waters, with δ18O of -1‰ and δD of -4.6‰, indicating enhanced evaporation of the pond water before infiltration, whereas there is a depleted isotopic composition in the confined units (δ18O = -4.3‰, δD = -20.4‰), which are also OM-poor. The Phreeqc model was used for quantitative calculation of the effect of pond losses on the different units. The Dissolved Inorganic Nitrogen (DIN) in the upper unit increases downstream from the ponds toward the sea, probably due to organic matter degradation, suggesting contribution of DIN from shallow groundwater flow to the sea. 87Sr/86Sr and Mg/Ca in the brackish and saline groundwater of the lower confined units increase toward seawater value, suggesting that the salinization process in the region

Salinization of porewater in a multiple aquitard-aquifer system in Jiangsu coastal plain, China

Science.gov (United States)

Li, Jing; Liang, Xing; Zhang, Yanian; Liu, Yan; Chen, Naijia; Abubakari, Alhassan; Jin, Menggui

2017-12-01

Chemical and isotopic compositions were analyzed in porewater squeezed from a clayey aquitard in Jiangsu coastal plain, eastern China, to interpret the salinity origin, chemical evolution and water-mass mixing process. A strong geochemical fingerprint was obtained with an aligned Cl/Br ratio of 154 in the salinized aquitard porewater over a wide Cl- concentration range (396-9,720 mg/L), indicating that porewater salinity is likely derived from a mixing with old brine with a proportion of less than 20%. Very small contributions of brine exerted limited effects on water stable isotopes. The relationships between porewater δ18O and δD indicate that shallow and intermediate porewaters could be original seawater and were subsequently diluted with modern meteoric water, whereas deep porewaters with depleted stable isotopic values were probably recharged during a cooler period and modified by evaporation and seawater infiltration. The cation-Cl relationship and mineralogy of associated strata indicate that porewater has been chemically modified by silicate weathering and ion-exchange reactions. 87Sr/86Sr ratios of 0.7094-0.7112 further confirm the input source of silicate minerals. Numerical simulations were used to evaluate the long-term salinity evolution of the deep porewater. The alternations of boundary conditions (i.e., the third aquifer mixed with brine at approximately 70 ka BP, followed by recharge of glacial meltwater at 20-25 ka BP, and then mixing with Holocene seawater at 7-10 ka BP) are responsible for the shift in porewater salinity. These timeframes correspond with the results of previous studies on ancient marine transgression-regression in Jiangsu coastal plain.

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

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.

Identification of the mechanisms and origin of salinization of groundwaters in coastal aquifers by means of isotopic techniques

International Nuclear Information System (INIS)

Araguas, L. J.; Quejido, A. J.

2007-01-01

To study the origin of salinity and the mechanisms operating in coastal aquifers, a set of tools is available to determine the essential aspects of the hydrogeological behaviour of the system. these tools are based on the integrated use of hydrochemical parameters (major constituents and trace elements) and isotopic parameters (oxygen, hydrogen, sulfur, carbon, strontium and boron). In addition to the active intrusion of seawater, salinization in coastal areas may be influenced by various human activities that accelerate the degradation of water quality, such as concentrated pumping, intensive farming techniques with return of irrigation water, or reuse of urban and industrial waste water. Characterization of the dominant processes and mechanisms is required for suitable management of the resource and implementation of corrective measures. (Author)

Isotopic and geochemical evidence of recharge sources and water quality in the Quaternary aquifer beneath Jinchang city, NW China

International Nuclear Information System (INIS)

Ma Jinzhu; Pan Feng; Chen Lihua; Edmunds, W. Mike; Ding Zhenyu; He Jianhua; Zhou Kunpeng; Huang Tianming

2010-01-01

Multiple isotopic and hydrogeochemical tracers were utilized to understand the recharge sources and geochemical evolution of groundwater in the Quaternary aquifer beneath Jinchang city and the adjacent Gobi desert area. The groundwater shows markedly depleted stable isotopic composition compared to modern rainfall. The signature of groundwaters from Jinchang and the northern Gobi desert area differ clearly from that of the alluvial fan in the south Yongchang basin and modern rainfall, and has lower or non-detectable 3 H activity, implying that the aquifer is likely maintained by palaeowater. This groundwater in the Gobi desert has a 14 C age older than 12 ka, indicating that the groundwater resources are non-renewable. The build-up of dissolved solids through evaporation is a major control on groundwater composition, and the dominant anion species change systematically from HCO 3 - , SO 4 2- to Cl - , but cations from weathering of albite, calcite, dolomite and gypsum also make a significant contribution. The scientific results have important implications for groundwater management in Jinchang city and as well as in the Shiyang River basin under China's West Development Strategy. It is recommended that the water allocation program of diverting water from the Dongda river to the Minqin basin be reconsidered.

Rapid estimation of aquifer salinity structure from oil and gas geophysical logs

Science.gov (United States)

Shimabukuro, D.; Stephens, M.; Ducart, A.; Skinner, S. M.

2016-12-01

We describe a workflow for creating aquifer salinity maps using Archie's equation for areas that have geophysical data from oil and gas wells. We apply this method in California, where geophysical logs are available in raster format from the Division of Oil, Gas, and Geothermal Resource (DOGGR) online archive. This method should be applicable to any region where geophysical logs are readily available. Much of the work is controlled by computer code, allowing salinity estimates for new areas to be rapidly generated. For a region of interest, the DOGGR online database is scraped for wells that were logged with multi-tool suites, such as the Platform Express or Triple Combination Logging Tools. Then, well construction metadata, such as measured depth, spud date, and well orientation, is attached. The resultant local database allows a weighted criteria selection of wells that are most likely to have the shallow resistivity, deep resistivity, and density porosity measurements necessary to calculate salinity over the longest depth interval. The algorithm can be adjusted for geophysical log availability for older well fields and density of sampling. Once priority wells are identified, a student researcher team uses Neuralog software to digitize the raster geophysical logs. Total dissolved solid (TDS) concentration is then calculated in clean, wet sand intervals using the resistivity-porosity method, a modified form of Archie's equation. These sand intervals are automatically selected using a combination of spontaneous potential and the difference in shallow resistivity and deep resistivity measurements. Gamma ray logs are not used because arkosic sands common in California make it difficult to distinguish sand and shale. Computer calculation allows easy adjustment of Archie's parameters. The result is a semi-continuous TDS profile for the wells of interest. These profiles are combined and contoured using standard 3-d visualization software to yield preliminary salinity

Experimental investigation of geochemical and mineralogical effects of CO2 sequestration on flow characteristics of reservoir rock in deep saline aquifers

Science.gov (United States)

Rathnaweera, T. D.; Ranjith, P. G.; Perera, M. S. A.

2016-01-01

Interactions between injected CO2, brine, and rock during CO2 sequestration in deep saline aquifers alter their natural hydro-mechanical properties, affecting the safety, and efficiency of the sequestration process. This study aims to identify such interaction-induced mineralogical changes in aquifers, and in particular their impact on the reservoir rock’s flow characteristics. Sandstone samples were first exposed for 1.5 years to a mixture of brine and super-critical CO2 (scCO2), then tested to determine their altered geochemical and mineralogical properties. Changes caused uniquely by CO2 were identified by comparison with samples exposed over a similar period to either plain brine or brine saturated with N2. The results show that long-term reaction with CO2 causes a significant pH drop in the saline pore fluid, clearly due to carbonic acid (as dissolved CO2) in the brine. Free H+ ions released into the pore fluid alter the mineralogical structure of the rock formation, through the dissolution of minerals such as calcite, siderite, barite, and quartz. Long-term CO2 injection also creates a significant CO2 drying-out effect and crystals of salt (NaCl) precipitate in the system, further changing the pore structure. Such mineralogical alterations significantly affect the saline aquifer’s permeability, with important practical consequences for the sequestration process. PMID:26785912

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

Science.gov (United States)

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

2018-01-01

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

Tracing groundwater salinization processes in coastal aquifers: a hydrogeochemical and isotopic approach in Na-Cl brackish waters of north-western Sardinia, Italy

Science.gov (United States)

Mongelli, G.; Monni, S.; Oggiano, G.; Paternoster, M.; Sinisi, R.

2013-01-01

In the Mediterranean area the demand of good quality water is often threatened by salinization, especially in coastal areas. The salinization is the result of concomitant processes due to both marine water intrusion and rock-water interaction, which in some cases are hardly distinguishable. In northwestern Sardinia, in the Nurra area, salinization due to marine water intrusion has been recently evidenced as consequence of bore hole exploitation. However, the geology of the Nurra records a long history from Paleozoic to Quaternary, resulting in relative structural complexity and in a wide variety of lithologies, including Triassic evaporites. To elucidate the origin of the saline component in the Nurra aquifer, may furnish a useful and more general model for the salinization processes in the Mediterranean area, where the occurrence of evaporitic rocks in coastal aquifers is a common feature. In addition, due to intensive human activities and recent climatic changes, the Nurra has become vulnerable to desertification and, similarly to other Mediterranean islands, surface-water resources can periodically suffer from drastic shortage. With this in mind we report new data, regarding brackish waters of Na-Cl type of the Nurra, including major ions and selected trace elements (B, Br, I and Sr) and isotopic data, including δ18O, δD in water, and δ34S and δ18O in dissolved sulphate. To better depict the origin of the salinity we also analyzed a set of Nurra Triassic evaporites for mineralogical and isotopic composition. The brackish waters have Cl contents up to 2025 mg L-1 and the ratios between dissolved ions and chlorine, with the exception of the Br/Cl ratio, are not those expected on the basis of a simple mixing between rain water and seawater. The δ18O and δD data indicate that most of the waters are within the Regional Meteoric Water Line and the Global Meteoric Water Line supporting the idea that they are meteoric in origin. A relevant consequence of the

The use of salinity contrast for density difference compensation to improve the thermal recovery efficiency in high-temperature aquifer thermal energy storage systems

NARCIS (Netherlands)

van Lopik, J.H.; Hartog, N.; Zaadnoordijk, Willem Jan

The efficiency of heat recovery in high-temperature (>60 °C) aquifer thermal energy storage (HT-ATES) systems is limited due to the buoyancy of the injected hot water. This study investigates the potential to improve the efficiency through compensation of the density difference by increased salinity

Analysis of pumping-induced unsaturated regions beneath aperennial river

Energy Technology Data Exchange (ETDEWEB)

Su, G.W.; Jasperse, J.; Seymour, D.; Constantz, J.; Zhou, Q.

2007-05-15

The presence of an unsaturated region beneath a streambedduring groundwater pumping near streams reduces the pumping capacity whenit reaches the well screens, changes flow paths, and alters the types ofbiological transformations in the streambed sediments. Athree-dimensional, multi-phase flow model of two horizontal collectorwells along the Russian River near Forestville, California was developedto investigate the impact of varying the ratio of the aquifer tostreambed permeability on (1) the formation of an unsaturated regionbeneath the stream, (2) the pumping capacity, (3) stream-water fluxesthrough the streambed, and (4) stream-water travel times to the collectorwells. The aquifer to streambed permeability ratio at which theunsaturated region was initially observed ranged from 10 to 100. The sizeof the unsaturated region beneath the streambed increased as the aquiferto streambed permeability ratio increased. The simulations also indicatedthat for a particular aquifer permeability, decreasing the streambedpermeability by only a factor of 2-3 from the permeability wheredesaturation initially occurred resulted in reducing the pumpingcapacity. In some cases, the stream-water fluxes increased as thestreambed permeability decreased. However, the stream water residencetimes increased and the fraction of stream water that reached that thewells decreased as the streambed permeability decreased, indicating thata higher streambed flux does not necessarily correlate to greaterrecharge of stream water around the wells.

Natural Tracers and Isotope Techniques to Define Groundwater Recharge and Salinization in the Bou Areg Coastal Aquifer (North Morocco)

Energy Technology Data Exchange (ETDEWEB)

Re, V. [Department of Molecular Sciences and Nanosystems, University Ca' Foscari, Venice (Italy); Allais, E. [ISO4 s.n.c., Torino (Italy); El Hamouti, N. [Multidisciplinary Faculty of Nador, University of Oujda, Nador (Morocco); Bouchnan, R. [Laboratory of Physical Phenomena and Natural Risk Modelling, University of Tangier, Tangier (Morocco); Sacchi, E. [Department of Earth Sciences, University of Pavia, Pavia (Italy); Rizzo, F. [UNESCO International Hydrological Programme, Paris (France); Zuppi, G. M. [Department of Molecular Sciences and Nanosystems, University Ca' Foscari, Venice and Institute of Environmental Geology and Geoengineering, National Research Council, Monterotondo (Italy)

2013-07-15

The geochemical and isotopic ({delta}{sup 2}H, {delta}{sup 18}O, {delta}{sup 13}C, {delta}{sup 15}N{sub NO3},{delta} {sup 18}O{sub NO3}) characterization of the Bou Areg aquifer (North Morocco) based on samples collected during two surveys in November 2009 and June 2010 allowed the identification of run-off from the mountain regions and agricultural return flows as the main sources of aquifer recharge. The high salinization of the aquifer is not only due to the intensive agricultural activities but it is also associated with the natural quality of the catchment. The isotopic signal of dissolved nitrates allowed for the identification of two main sources of nitrogen in the system: (i) fertilizers and (ii) manure and septic effluents. The study, framed within the UNESCO-IHP sub component of the Strategic Partnership for the Mediterranean Large Marine Ecosystem, represents the first isotopic investigation of the area and will serve as a basis for the promotion of robust science based management practices in the region. (author)

Groundwater salinity study in the Mekong Delta using isotope techniques

International Nuclear Information System (INIS)

Le Van Khoi, Nguyen Kien Chinh; Do Tien Hung

2002-01-01

Environmental isotopes D, 18 O and chemical composition were used for study of recharge and salinization of groundwater in the are located between Bassac and Mekong Rivers. The results showed that: (a) Pleistocene aquifers are recharged through flood plains and outcrops located at the same altitude. The sanility of groundwater in these aquifers is mostly due to dissolution of the aquifer material, (b) Pliocene and Miocene aquifers receive recharge through outcrops located at the higher altitude on the northeast extension of the Delta and Cambodia. The salinity of groundwater in the coastal region of the aquifer is attributable to sea water intrusion. There appears to be significant retention of sea water in the coastal sediment during intrusion. (Author)

State of the art and risk analysis for CO2 storage in a saline aquifer. Investigation report

International Nuclear Information System (INIS)

Farret, R.; Gombert, P.; Hulot, C.; BOUR, Olivier; Thoraval, Alain

2010-01-01

This study deals with the impact of supercritical CO 2 injection in deep saline aquifer, but also addresses the case of depleted hydrocarbons fields. After a general presentation of the carbon capture and storage (CCS) technique, this report presents the main principles of risk analysis and defines an analysis method applicable to the whole CCS sector. It is based on practices coming from the field of industrial risk analysis, on the knowledge of underground processes, and on the state of the art of health risk analysis in the case of chemical species. The main considered risks are hydraulic risks (fluid pressurization), mechanical risks (cracking, soil rising and induced seismicity), CO 2 migration or leakages towards aquifers and surface, and migration of other species than CO 2 . The report addresses the characterisation of fluids and of possible geochemical evolutions, the characterisation of scenarios of fluid migration, and the hierarchy of health impacts related to fluid leakages

A Geology-Based Estimate of Connate Water Salinity Distribution

Science.gov (United States)

2014-09-01

poses serious environmental concerns if connate water is mobilized into shallow aquifers or surface water systems. Estimating the distribution of...groundwater flow and salinity transport near the Herbert Hoover Dike (HHD) surrounding Lake Okeechobee in Florida . The simulations were conducted using the...on the geologic configuration at equilibrium, and the horizontal salinity distribution is strongly linked to aquifer connectivity because

A Search for Freshwater in the Saline Aquifers of Coastal Bangladesh

Science.gov (United States)

Peters, C.; Hornberger, G. M.

2017-12-01

Can we locate pockets of freshwater amidst brackish groundwater in remote villages in Bangladesh? This study explores what we can infer about local groundwater-surface water (GW-SW) interactions in the polders of coastal Bangladesh. In this underdeveloped region, the shallow groundwater is primarily brackish with unpredictable apportioning of freshwater pockets. We use transects of piezometers, cores, electromagnetic induction, and water chemistry surveys to explore two sources of potential fresh groundwater: (1) tidal channel-aquifer exchange and (2) meteoric recharge. Freshwater is difficult to find due to disparate subsurface lithology, asymmetrical tidal dynamics, extreme seasonal fluctuations in rainfall, and limited field data. Observations suggest substantial lateral variability in shallow subsurface conductivity profiles as well as tidal pressure signals in piezometers. Nevertheless, active exchange of freshwater may be limited due to low permeability of banks and surface sediments limits. Small scale heterogeneity in delta formation likely caused much of the groundwater salinity variation. Without adequate ground truthing of groundwater quality, the ability to deduce the exact location of freshwater pockets may be restricted.

Biogeochemical cycling of arsenic in coastal salinized aquifers: Evidence from sulfur isotope study

International Nuclear Information System (INIS)

Kao, Yu-Hsuan; Wang, Sheng-Wei; Liu, Chen-Wuing; Wang, Pei-Ling; Wang, Chung-Ho; Maji, Sanjoy Kumar

2011-01-01

Arsenic (As) contamination of groundwater, accompanied by critical salinization, occurs in the southwestern coastal area of Taiwan. Statistical analyses and geochemical calculations indicate that a possible source of aqueous arsenic is the reductive dissolution of As-bearing iron oxyhydroxides. There are few reports of the influence of sulfate-sulfide redox cycling on arsenic mobility in brackish groundwater. We evaluated the contribution of sulfate reduction and sulfide re-oxidation on As enrichment using δ 34 S [SO 4 ] and δ 18 O [SO 4 ] sulfur isotopic analyses of groundwater. Fifty-three groundwater samples were divided into groups of high-As content and salinized (Type A), low-As and non-salinized (Type B), and high-As and non-salinized (Type C) groundwaters, based on hydro-geochemical analysis. The relatively high enrichment of 34 S [SO 4 ] and 18 O [SO 4 ] present in Type A, caused by microbial-mediated reduction of sulfate, and high 18 O enrichment factor (ε [SO 4 -H 2 O] ), suggests that sulfur disproportionation is an important process during the reductive dissolution of As-containing iron oxyhydroxides. Limited co-precipitation of ion-sulfide increased the rate of As liberation under anaerobic conditions. In contrast to this, Type B and Type C groundwater samples showed high δ 18 O [SO 4 ] and low δ 34 S [SO 4 ] values under mildly reducing conditions. Base on 18 O mass balance calculations, the oxide sources of sulfate are from infiltrated atmospheric O 2 , caused by additional recharge of dissolved oxygen and sulfide re-oxidation. The anthropogenic influence of extensive pumping also promotes atmospheric oxygen entry into aquifers, altering redox conditions, and increasing the rate of As release into groundwater. - Highlights: → Seawater intrusion and elevated As are the main issues of groundwater in Taiwan. → Sulfur and oxygen isotopes of sulfate were analyzed to evaluate the As mobility. → Reductive dissolution of Fe minerals and

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

KAUST Repository

Allen, Rebecca

2011-05-01

An increase in the earth’s surface temperature has been directly linked to the rise of carbon dioxide (CO2) levels In the atmosphere and an enhanced greenhouse effect. CO2 sequestration is one of the proposed mitigation Strategies in the effort to reduce atmospheric CO2 concentrations. Globally speaking, saline aquifers provide an adequate storage capacity for the world’s carbon emissions, and CO2 sequestration projects are currently underway in countries such as Norway, Germany, Japan, USA, and others. Numerical simulators serve as predictive tools for CO2 storage, yet must model fluid transport behavior while coupling different transport processes together accurately. With regards to CO2 sequestration, an extensive amount of research has been 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 storage capacity in saline aquifers, due to the density increase between pure fluid and CO2‐saturated fluid. This work presents the transport modeling equations that are used for diffusive- convective modeling. A cell-centered finite difference method is used, and simulations are run using MATLAB. Two cases are explored in order to compare the results from this work’s self-generated code with the results published in literature. Simulation results match relatively well, and the discrepancy for a delayed onset time of convective transport observed in this work is attributed to numerical artifacts. In fact, onset time in this work is directly attributed to the instability of the physical system: this instability arises from non-linear coupling of fluid flow, transport, and convection, but is triggered by numerical errors in these simulations. Results from this work enable the computation of a value for the numerical constant that appears in the onset time equation that

Numerical simulation of flow in deep open boreholes in a coastal freshwater lens, Pearl Harbor Aquifer, O‘ahu, Hawai‘i

Science.gov (United States)

Rotzoll, Kolja

2012-01-01

The Pearl Harbor aquifer in southern O‘ahu is one of the most important sources of freshwater in Hawai‘i. A thick freshwater lens overlays brackish and saltwater in this coastal aquifer. Salinity profiles collected from uncased deep monitor wells (DMWs) commonly are used to monitor freshwater-lens thickness. However, vertical flow in DMWs can cause the measured salinity to differ from salinity in the adjacent aquifer or in an aquifer without a DWM. Substantial borehole flow and displacement of salinity in DMWs over several hundred feet have been observed in the Pearl Harbor aquifer. The objective of this study was to evaluate the effects of borehole flow on measured salinity profiles from DMWs. A numerical modeling approach incorporated aquifer hydraulic characteristics and recharge and withdrawal rates representative of the Pearl Harbor aquifer. Borehole flow caused by vertical hydraulic gradients associated with both the natural regional flow system and groundwater withdrawals was simulated. Model results indicate that, with all other factors being equal, greater withdrawal rates, closer withdrawal locations, or higher hydraulic conductivities of the well cause greater borehole flow and displacement of salinity in the well. Borehole flow caused by the natural groundwater-flow system is five orders of magnitude greater than vertical flow in a homogeneous aquifer, and borehole-flow directions are consistent with the regional flow system: downward flow in inland recharge areas and upward flow in coastal discharge areas. Displacement of salinity inside the DMWs associated with the regional groundwater-flow system ranges from less than 1 to 220 ft, depending on the location and assumed hydraulic conductivity of the well. For example, upward displacements of the 2 percent and 50 percent salinity depths in a well in the coastal discharge part of the flow system are 17 and 4.4 ft, respectively, and the average salinity difference between aquifer and borehole is 0

Hydrodynamic framework of Saharan Triassic aquifers in South Tunisia and Algeria

Science.gov (United States)

Dhia, H. Ben; Chiarelli, A.

The main characteristics of the lower Triassic in the Saharan part of Tunisia are presented. This first study of the aquifer is made possible because of data available from numerous petroleum wells that exist in the region. The results show that the reservoir is of importance for either geothermal energy recovering or human water needs; especially since its salinity lies in the range 2 g/l to 60 g/l. Along the Tunisian-Llibyan frontier, because of its pressure and salinity (<3 g/l), the aquifer can be used for regional needs. The study also shows that the salinity gradient (SE-NW) increases orthogonally to the runoff direction (SW-NE). This phenomenon was unexpected and it is necessary to consider the aquifer in its regional North African framework and to include its Algerian part to understand it; when the salinity and potentiometric maps include both countries, a regional pattern is evident. Furthermore, a correspondence is noted between the salinity variations and the percentage of detritic elements in the reservoir. Salinity increases toward the NW, while the detritic elements decrease in that direction. Zones with salt content lower than 5 g/l seem to be related to good reservoirs and shales, that are rich in sands, and carbonates. The aquifer water supply is primarily linked to gravity flow and secondarily to compaction flow.

Isotopic and chemical investigations of quaternary aquifer in sinai peninsula

International Nuclear Information System (INIS)

Sadek, M.A.; Ahmed, M.A.; Awad, M.A.

2001-01-01

The present study has been conducted to investigate the renewal activity and mineralization potential of the quaternary aquifer in Sinai peninsula using environmental isotopes and hydrochemistry. The quaternary aquifer is vital for development processes as it has a wide extension and shallow water table. The total dissolved salts vary greatly from one location to another and range widely between 510-7060 mg/1, reflecting all categories from fresh to saline water. The change in salinity all over Sinai can be attributed to variations in the rate of evaporation. Leaching and dissolution of terrestrial salts during floods as well as the effects of sea spray and saline water intrusion. The main sources of groundwater recharge are the infiltration of Local precipitation and surface runoff as well as lateral flow through hydraulic connection with fractured aquifers. Snow melt also contributes to aquifer recharge in some areas in the central part of southern Sinai. The environmental stable isotopic contents of the ground water in the quaternary aquifer in Sinai reflect the isotopic composition of rain water from continental and east Mediterranean precipitation and monsonal air mass which comes from Indian ocean as well as the seepage of partly evaporated floodwater. The southern samples are more suitable for drinking and irrigation purposes due to its lower salinity and sodium hazard

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

Sulfur isotopic study of sulfate in the aquifer of Costa de Hermosillo (Sonora, Mexico) in relation to upward intrusion of saline groundwater, irrigation pumping and land cultivation

International Nuclear Information System (INIS)

Szynkiewicz, Anna; Medina, Miguel Rangel; Modelska, Magdalena; Monreal, Rogelio; Pratt, Lisa M.

2008-01-01

Groundwater from the Costa de Hermosillo aquifer has been used extensively for irrigation over the past 60 a in the Sonora region of northwestern Mexico resulting in salinization of fresh groundwater resources. Salinization of groundwater is most pronounced on the western/coastal side of the aquifer, with an aerial extent of 26.7 km 2 , where maximum values are reported for conductivity (31 mS/cm) and Cl - concentrations (16,271 mg/L). Salinization is likely to increase if groundwater pumping continues at levels comparable to the present time. Upward incursion of marine water into the aquifer is inferred from δ 2 H (-7.2 per mille ) and δ 18 O (+1.6 per mille ) compositions of groundwater samples with the highest conductivity. Compared to modern seawater in the Gulf of California, ratios of SO 4 /Cl and Cl/Br are small (0.01 and 33, respectively) and the S isotopic composition of SO 4 2- is high (+32.7%) in the most saline portions of the Costa de Hermosillo. This saline groundwater is inferred to result from an earlier phase of dissimilatory bacterial SO 4 2- reduction coupled to decomposition of organic matter in marine blue clays deposited during the Miocene/Pliocene transgression. The isotopic composition of present-day surface discharge from agricultural fields is substantially enriched in 32 S due to widespread application of (NH 4 ) 2 SO 4 fertilizers and potential mobilization of S from mineral resources. Surface water discharging from irrigated fields has δ 34 S values ranging from -2.1 to 3.3 per mille which are distinctly different from groundwater and surface water in adjacent non-agricultural areas with δ 34 S values ranging from 5.2 to 13.5 per mille . Prolonged irrigation pumping that promotes the incursion of air to the subsurface could enhance the weathering of S-bearing minerals such as magmatic sulfides, producing 32 S-enriched SO 4 2-

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.

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

Monitoring of the microbial community composition of the saline aquifers during CO2 storage by fluorescence in situ hybridisation

OpenAIRE

Daria Morozova; M. Wandrey; Mashal Alawi; Martin Zimmer; Andrea Vieth-Hillebrand [Vieth; M. Zettlitzer; Hilke Würdemann

2010-01-01

This study reveals the first analyses of the composition and activity of the microbial community of a saline CO2 storage aquifer. Microbial monitoring during CO2 injection has been reported. By using fluorescence in situ hybridisation (FISH), we have shown that the microbial community was strongly influenced by the CO2 injection. Before CO2 arrival, up to 6 × 106 cells ml−1 were detected by DAPI staining at a depth of 647 m below the surface. The microbial community was dominated by the dom...

Numerical Study of Groundwater Flow and Salinity Distribution Cycling Controlled by Seawater/Freshwater Interaction in Karst Aquifer Using SEAWAT

Science.gov (United States)

Xu, Z.; Hu, B.

2017-12-01

The interest to predict seawater intrusion and salinity distribution in Woodville Karst Plain (WKP) has increased due to the huge challenge on quality of drinkable water and serious environmental problems. Seawater intrudes into the conduit system from submarine karst caves at Spring Creek Spring due to density difference and sea level rising, nowadays the low salinity has been detected at Wakulla Spring which is 18 km from coastal line. The groundwater discharge at two major springs and salinity distribution in this area is controlled by the seawater/freshwater interaction under different rainfall conditions: during low rainfall periods, seawater flow into the submarine spring through karst windows, then the salinity rising at the submarine spring leads to seawater further intrudes into conduit system; during high rainfall periods, seawater is pushed out by fresh water discharge at submarine spring. The previous numerical studies of WKP mainly focused on the density independent transport modeling and seawater/freshwater discharge at major karst springs, in this study, a SEAWAT model has been developed to fully investigate the salinity distribution in the WKP under repeating phases of low rainfall and high rainfall periods, the conduit system was simulated as porous media with high conductivity and porosity. The precipitation, salinity and discharge at springs were used to calibrate the model. The results showed that the salinity distribution in porous media and conduit system is controlled by the rainfall change, in general, the salinity distribution inland under low rainfall conditions is much higher and wider than the high rainfall conditions. The results propose a prediction on the environmental problem caused by seawater intrusion in karst coastal aquifer, in addition, provide a visual and scientific basis for future groundwater remediation.

Aquifer composition and the tendency toward scale-deposit formation during reverse osmosis desalination - Examples from saline ground water in New Mexico, USA

Science.gov (United States)

Huff, G.F.

2006-01-01

Desalination is expected to make a substantial contribution to water supply in the United States by 2020. Currently, reverse osmosis is one of the most cost effective and widely used desalination technologies. The tendency to form scale deposits during reverse osmosis is an important factor in determining the suitability of input waters for use in desalination. The tendency toward scale formation of samples of saline ground water from selected geologic units in New Mexico was assessed using simulated evaporation. All saline water samples showed a strong tendency to form CaCO3 scale deposits. Saline ground water samples from the Yeso Formation and the San Andres Limestone showed relatively stronger tendencies to form CaSO4 2H2O scale deposits and relatively weaker tendencies to form SiO2(a) scale deposits than saline ground water samples from the Rio Grande alluvium. Tendencies toward scale formation in saline ground water samples from the Dockum Group were highly variable. The tendencies toward scale formation of saline waters from the Yeso Formation, San Andres Limestone, and Rio Grande alluvium appear to correlate with the mineralogical composition of the geologic units, suggesting that scale-forming tendencies are governed by aquifer composition and water-rock interaction. ?? 2006 Elsevier B.V. All rights reserved.

Combined use of heat and saline tracer to estimate aquifer properties in a forced gradient test

Science.gov (United States)

Colombani, N.; Giambastiani, B. M. S.; Mastrocicco, M.

2015-06-01

Usually electrolytic tracers are employed for subsurface characterization, but the interpretation of tracer test data collected by low cost techniques, such as electrical conductivity logging, can be biased by cation exchange reactions. To characterize the aquifer transport properties a saline and heat forced gradient test was employed. The field site, located near Ferrara (Northern Italy), is a well characterized site, which covers an area of 200 m2 and is equipped with a grid of 13 monitoring wells. A two-well (injection and pumping) system was employed to perform the forced gradient test and a straddle packer was installed in the injection well to avoid in-well artificial mixing. The contemporary continuous monitor of hydraulic head, electrical conductivity and temperature within the wells permitted to obtain a robust dataset, which was then used to accurately simulate injection conditions, to calibrate a 3D transient flow and transport model and to obtain aquifer properties at small scale. The transient groundwater flow and solute-heat transport model was built using SEAWAT. The result significance was further investigated by comparing the results with already published column experiments and a natural gradient tracer test performed in the same field. The test procedure shown here can provide a fast and low cost technique to characterize coarse grain aquifer properties, although some limitations can be highlighted, such as the small value of the dispersion coefficient compared to values obtained by natural gradient tracer test, or the fast depletion of heat signal due to high thermal diffusivity.

Potential for saltwater intrusion into the lower Tamiami aquifer near Bonita Springs, southwestern Florida

Science.gov (United States)

Shoemaker, W. Barclay; Edwards, K. Michelle

2003-01-01

A study was conducted to examine the potential for saltwater intrusion into the lower Tamiami aquifer beneath Bonita Springs in southwestern Florida. Field data were collected, and constant- and variable-density ground-water flow simulations were performed that: (1) spatially quantified modern and seasonal stresses, (2) identified potential mechanisms of saltwater intrusion, and (3) estimated the potential extent of saltwater intrusion for the area of concern. MODFLOW and the inverse modeling routine UCODE were used to spatially quantify modern and seasonal stresses by calibrating a constant-density ground-water flow model to field data collected in 1996. The model was calibrated by assuming hydraulic conductivity parameters were accurate and by estimating unmonitored ground-water pumpage and potential evapotranspiration with UCODE. Uncertainty in these estimated parameters was quantified with 95-percent confidence intervals. These confidence intervals indicate more uncertainty (or less reliability) in the estimates of unmonitored ground-water pumpage than estimates of pan-evaporation multipliers, because of the nature and distribution of observations used during calibration. Comparison of simulated water levels, streamflows, and net recharge with field data suggests the model is a good representation of field conditions. Potential mechanisms of saltwater intrusion into the lower Tamiami aquifer include: (1) lateral inland movement of the freshwater-saltwater interface from the southwestern coast of Florida; (2) upward leakage from deeper saline water-bearing zones through natural upwelling and upconing, both of which could occur as diffuse upward flow through semiconfining layers, conduit flow through karst features, or pipe flow through leaky artesian wells; (3) downward leakage of saltwater from surface-water channels; and (4) movement of unflushed pockets of relict seawater. Of the many potential mechanisms of saltwater intrusion, field data and variable

Biogeochemical cycling of arsenic in coastal salinized aquifers: Evidence from sulfur isotope study

Energy Technology Data Exchange (ETDEWEB)

Kao, Yu-Hsuan [Department of Bioenvironmental Systems Engineering, National Taiwan University, Taipei 106, Taiwan, ROC (China); Wang, Sheng-Wei [Agricultural Engineering Research Center, Chungli 320, Taiwan, ROC (China); Liu, Chen-Wuing, E-mail: lcw@gwater.agec.ntu.edu.tw [Department of Bioenvironmental Systems Engineering, National Taiwan University, Taipei 106, Taiwan, ROC (China); Wang, Pei-Ling [Institute of Oceanography, National Taiwan University, Taipei 106, Taiwan, ROC (China); Wang, Chung-Ho [Institute of Earth Sciences, Academia Sinica, Taipei 115, Taiwan, ROC (China); Maji, Sanjoy Kumar [Department of Bioenvironmental Systems Engineering, National Taiwan University, Taipei 106, Taiwan, ROC (China)

2011-10-15

Arsenic (As) contamination of groundwater, accompanied by critical salinization, occurs in the southwestern coastal area of Taiwan. Statistical analyses and geochemical calculations indicate that a possible source of aqueous arsenic is the reductive dissolution of As-bearing iron oxyhydroxides. There are few reports of the influence of sulfate-sulfide redox cycling on arsenic mobility in brackish groundwater. We evaluated the contribution of sulfate reduction and sulfide re-oxidation on As enrichment using {delta}{sup 34}S{sub [SO{sub 4]}} and {delta}{sup 18}O{sub [SO{sub 4]}} sulfur isotopic analyses of groundwater. Fifty-three groundwater samples were divided into groups of high-As content and salinized (Type A), low-As and non-salinized (Type B), and high-As and non-salinized (Type C) groundwaters, based on hydro-geochemical analysis. The relatively high enrichment of {sup 34}S{sub [SO{sub 4]}} and {sup 18}O{sub [SO{sub 4]}} present in Type A, caused by microbial-mediated reduction of sulfate, and high {sup 18}O enrichment factor ({epsilon}{sub [SO{sub 4-H{sub 2O]}}}), suggests that sulfur disproportionation is an important process during the reductive dissolution of As-containing iron oxyhydroxides. Limited co-precipitation of ion-sulfide increased the rate of As liberation under anaerobic conditions. In contrast to this, Type B and Type C groundwater samples showed high {delta}{sup 18}O{sub [SO{sub 4]}} and low {delta}{sup 34}S{sub [SO{sub 4]}} values under mildly reducing conditions. Base on {sup 18}O mass balance calculations, the oxide sources of sulfate are from infiltrated atmospheric O{sub 2}, caused by additional recharge of dissolved oxygen and sulfide re-oxidation. The anthropogenic influence of extensive pumping also promotes atmospheric oxygen entry into aquifers, altering redox conditions, and increasing the rate of As release into groundwater. - Highlights: {yields} Seawater intrusion and elevated As are the main issues of groundwater in Taiwan

Simplified models of transport and reactions in conditions of CO2 storage in saline aquifers

Science.gov (United States)

Suchodolska, Katarzyna; Labus, Krzysztof

2016-04-01

and pore fluid migration within the analyzed aquifers were characterized based on the two-dimensional model. Their mechanism is controlled by, changing with time, density contrasts between supercritical CO2, the initial brine, and the brine with CO2 dissolved. When modeling the impact of CO2 storage on the aquifer and cap-rock interface we noted, that decrease in porosity, resulting from a positive balance of secondary minerals volume, was visible mainly in aquifer rocks. Porosity remained almost constant in cap-rocks, to the advantage of sealing of the repository. We also observed, that mineralogical changes at the interface zone, differ from those which occur in central parts of aquifer and cap-rock. This can be explained by high gas saturation in the aquifer roof, and by formation of a front of pore fluids migrating outwards from the interface zone. Due to these mechanisms, at the base of cap-rock, the phenomenon of CO2 desequestration may temporarily occur, associated with the dissolution of carbonate minerals. The simplified models described, may be applicable in assessment of carbon dioxide trapped by dissolution and in mineral phases, and also evaluation of petrostructural consequences of CO2 injection into saline aquifers. This allows estimation of suitability of given formations for CO2 sequestration. The project was funded by the National Science Centre (Poland) granted on the basis of the decision DEC-2012/05/B/ST10/00416.

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

Direct Evidence of Meltwater Flow Within a Firn Aquifer in Southeast Greenland

Science.gov (United States)

Miller, Olivia; Solomon, D. Kip; Miège, Clément; Koenig, Lora; Forster, Richard; Schmerr, Nicholas; Ligtenberg, Stefan R. M.; Montgomery, Lynn

2018-01-01

Within the lower percolation zone of the southeastern Greenland ice sheet, meltwater has accumulated within the firn pore space, forming extensive firn aquifers. Previously, it was unclear if these aquifers stored or facilitated meltwater runoff. Following mixing of a saline solution into boreholes within the aquifer, we observe that specific conductance measurements decreased over time as flowing freshwater diluted the saline mixture in the borehole. These tests indicate that water flows through the aquifer with an average specific discharge of 4.3 × 10-6 m/s (σ = 2.5 × 10-6 m/s). The specific discharge decreases dramatically to 0 m/s, defining the bottom of the aquifer between 30 to 50 m depth. The observed flow indicates that the firn pore space is a short-term (ocean.

Saline-water intrusion related to well construction in Lee County, Florida

Science.gov (United States)

Boggess, Durward Hoye; Missimer, T.M.; O'Donnell, T. H.

1977-01-01

Ground water is the principle source of water supply in Lee County, Florida where an estimated 30,000 wells have been drilled since 1990. These wells ranges in depth from about 10 to 1,240 feet and tap the water table aquifer or one or more of the artesian water-bearing units or zones in the Tamiami Formation, the upper part of the Hawthorn Formation, the lower part of the Hawthorn Formation and the Tampa Limestone and the Suwannee Limestone. Before 1968, nearly all wells were constructed with galvanized or black iron pipe. Many of these wells are sources of saline-water intrusion into freshwater-bearing zones. The water-bearing zones in the lower part of the Hawthorn Formation, Tampa Limestone, and Suwannee Limestone are artesian-they have higher water levels and usually contain water with a higher concentration of dissolved solids than do the aquifers occurring at shallower depths. The water from these deeper aquifers generally range in dissolved solids concentration from about 1,500 to 2,400 mg/L, and in chloride from about 500 to 1,00 mg/L. A maximum chloride concentration of 15,200 mg/L has been determined. Few of the 3,00 wells estimated to have been drilled to these zones contain sufficient casing to prevent upward flow into overlaying water-bearing zones. Because of water-level differentials, upward movement and lateral intrusion of saline water occurs principally into the upper part of the Hawthorn Formation where the chloride concentrations in water unaffected by saline-water intrusion ranges from about 80 to 150 mg/L. Where intrusion from deep artesian zones has occurred, the chloride concentration in water from the upper part of the Hawthorn Formation ranges from about 300 to more than 2,100 mg/L Surface discharges of the saline water from wells tapping the lower part of the Hawthorn Formation and the Suwannee Limestone also had affected the water-table aquifer which normally contains water with 10 to 50 mg/L of chloride. In one area, the chloride

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.

Geochemical modelling of worst-case leakage scenarios at potential CO2-storage sites - CO2 and saline water contamination of drinking water aquifers

Science.gov (United States)

Szabó, Zsuzsanna; Edit Gál, Nóra; Kun, Éva; Szőcs, Teodóra; Falus, György

2017-04-01

Carbon Capture and Storage is a transitional technology to reduce greenhouse gas emissions and to mitigate climate change. Following the implementation and enforcement of the 2009/31/EC Directive in the Hungarian legislation, the Geological and Geophysical Institute of Hungary is required to evaluate the potential CO2 geological storage structures of the country. Basic assessment of these saline water formations has been already performed and the present goal is to extend the studies to the whole of the storage complex and consider the protection of fresh water aquifers of the neighbouring area even in unlikely scenarios when CO2 injection has a much more regional effect than planned. In this work, worst-case scenarios are modelled to understand the effects of CO2 or saline water leaks into drinking water aquifers. The dissolution of CO2 may significantly change the pH of fresh water which induces mineral dissolution and precipitation in the aquifer and therefore, changes in solution composition and even rock porosity. Mobilization of heavy metals may also be of concern. Brine migration from CO2 reservoir and replacement of fresh water in the shallower aquifer may happen due to pressure increase as a consequence of CO2 injection. The saline water causes changes in solution composition which may also induce mineral reactions. The modelling of the above scenarios has happened at several methodological levels such as equilibrium batch, kinetic batch and kinetic reactive transport simulations. All of these have been performed by PHREEQC using the PHREEQC.DAT thermodynamic database. Kinetic models use equations and kinetic rate parameters from the USGS report of Palandri and Kharaka (2004). Reactive transport modelling also considers estimated fluid flow and dispersivity of the studied formation. Further input parameters are the rock and the original ground water compositions of the aquifers and a range of gas-phase CO2 or brine replacement ratios. Worst-case scenarios

Simulation of Groundwater Mounding Beneath Hypothetical Stormwater Infiltration Basins

Science.gov (United States)

Carleton, Glen B.

2010-01-01

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

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

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

Characterization of the lowland coastal aquifer of Comacchio (Ferrara, Italy): Hydrology, hydrochemistry and evolution of the system

Science.gov (United States)

Giambastiani, B. M. S.; Colombani, N.; Mastrocicco, M.; Fidelibus, M. D.

2013-09-01

This study delineates the actual hydrogeochemistry and the geological evolution of an unconfined coastal aquifer located in a lowland setting in order to understand the drivers of the groundwater salinization. Physical aquifer parameterization highlights a vertical hydraulic gradient due to the presence of a heavy drainage system, which controls the hydrodynamics of this coastal area, forcing groundwater to flow from the bottom toward the top of the aquifer. As a consequence, relict seawater in stable density stratification, preserved within low permeability sediments in the deepest portion of the aquifer, has been drawn upward. The hydrogeochemical investigations allow identifying the role of seepage and water-sediment interactions in the aquifer salinization process and in the modification of groundwater chemistry. Mixing between freshwater and saltwater occurs; however, it is neither the only nor the dominant process driving groundwater hydrochemistry. In the aquifer several concurring and competing water-sediment interactions - as NaCl solution, ion-exchange, calcite and dolomite dissolution/precipitation, oxidation of organic matter, and sulfate bacterial reduction - are triggered by or overlap freshwater-saltwater mixing The hyper-salinity found in the deepest portion of the aquifer cannot be associated with present seawater intrusion, but suggests the presence of salt water of marine origin, which was trapped in the inter-basin during the Holocene transgression. The results of this study contribute to a better understanding of groundwater dynamics and salinization processes in this lowland coastal aquifer.

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

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

Isotopes to Study the coastal aquifer plain, Cap Bon, Tunisia

International Nuclear Information System (INIS)

Ben Hamouda, M. F.; Zouari, Kamel; Tarhouni, J.; Gaye, C.B.; Oueslati, M.N.

2005-01-01

The study area is located in the northeastern part of Tunisia about 60 km south of the Tunis city. It is bounded by the Gulf of Haematite in the East, Djebel Sidi Aberahmane in the West, The town of Nabeul in the south and the area of the town Kelibia in the north. The landscape is a coastal plain slightly sloping (3%) towards the sea. The groundwater of the Oriental coast aquifer system occurs mainly at two levels, a shallow aquifer up to depths of about 50 m whose reservoir is consisted by sediments of the Plio quaternary and a deep aquifer between about 150 and 400 m located in the sand stone formations of Miocene of the anticline of Djebel Sidi Abderrahmene. The climate of the region is semi-arid to sub-humid and of Mediterranean type. There are no perennial rivers in this region; but intense storms occasionally cause surface runoff, which is discharged by the oueds. The study is related to a technical cooperation project with the International Atomic Energy Agency, Vienna, Austria, aimed at the use of isotope techniques to study the seawater intrusion into the coastal aquifers of Cap Bon in Tunisia. In this regard, a better understanding of the recharge and flow regime as well as the origin or salinity of the groundwater was required. To reach this goal, isotope and geochemical investigations were carried out. Water samples were taken from wells, boreholes from deep and shallow aquifer of the Oriental coastal aquifer located between Beni Khiar in the south and Kelibia in the north. The samples were analysed for their chemical and isotopic compositions (18O, 2H, 3H, 13C, 14C, 34S). In the following, the results of these analyses are presented and discussed in terms of the recharge and flow regime of the groundwater and the origin and evolution of its salinity. The results of geochemical and isotopic studies have shown that the groundwater is very eterogeneous and suggest the aquifer is replenished by recent water coming from direct infiltration from rain. At

The origin of increased salinity in the Cambrian-Vendian aquifer system on the Kopli Peninsula, northern Estonia

Science.gov (United States)

Karro, Enn; Marandi, Andres; Vaikmäe, Rein

Monitoring of the confined Cambrian-Vendian aquifer system utilised for industrial water supply at Kopli Peninsula in Tallinn over 24 years reveals remarkable changes in chemical composition of groundwater. A relatively fast 1.5 to 3.0-fold increase in TDS and in concentrations of major ions in ed groundwater is the consequence of heavy pumping. The main sources of dissolved load in Cambrian-Vendian groundwater are the leaching of host rock and the other geochemical processes that occur in the saturated zone. Underlying crystalline basement, which comprises saline groundwater in its upper weathered and fissured portion, and which is hydraulically connected with the overlying Cambrian-Vendian aquifer system, is the second important source of ions. The fractured basement and its clayey weathering crust host the Ca-Cl type groundwater, which is characterised by high TDS values (2-20 g/L). Intensive water ion accelerates the exchange of groundwaters and increases the area of influence of pumping. Chemical and isotopic studies of groundwater indicate an increasing contribution of old brackish water from the crystalline basement and rule out the potential implication of an intrusion of seawater into aquifer. L'origine de la salinité croissante dans le système aquifère du Cambrien-Vendien dans la péninsule de Kopli, nord de l'Estonie Le suivi à long terme du système aquifère captif du Cambrien-Vendien utilisé pour l'approvisionnement d'eaux industrielles dans la Péninsule de Kopli, nord de l'Estonie, révèle de remarquables changements dans la composition chimique des eaux souterraines. Une augmentation de facteur 1.5 à 3 de la TDS et des concentrations en ions majeurs dans l'eau souterraine est la conséquence de pompages intensifs. Les sources principales des charges dissoutes dans les eaux de l'aquifère du Cambrien-Vendien sont le lessivage des roches et d'autres phénomènes géochimiques ayant lieu dans la zone saturée. Le soubassement rocheux cristallin

A Comprehensive evaluation of groundwater vulnerability to saltwater up-coning and sea water intrusion in a coastal aquifer (case study: Ghaemshahr-juybar aquifer)

Science.gov (United States)

Motevalli, Alireza; Moradi, Hamid Reza; Javadi, Saman

2018-02-01

Aquifer salinization has recently increased significantly due to human activity and has caused irreparable environmental and economic effects. In this research, a new method is proposed for modeling the vulnerability to salinity for the Ghaemshahr-juybar aquifer. Specifically, the GALDIT (Sea water intrusion) and TAWLBIC (Saltwater up-coning) indices were combined to produce a map of vulnerability (Comprehensive Salinity Index or CSI) to seawater intrusion of a region near the coast and saltwater up-coning away from the coast, respectively. Single parameter and removal layer sensitivity analysis were performed in order to identify the sensitive parameters and achieve optimal weights (through the single-parameter method) of contributing factors in all three methods. The three optimized methods produced were GALDIT-Opt, TAWLBIC-Opt and CSI-Opt. To assess the accuracy of the original maps and optimal ones, the Pearson correlation was used. Results indicated that the Pearson correlation of the optimized GALDIT, TAWLBIC and CSI model was better than GALDIT, TAWLBIC and CSI. The results show that the increase in correlation between EC (Electrical Conductivity), TDS (Total Dissolved Solids) and SAR (Sodium Adsorption Ratio) from the GALDIT model to the CSI-Opt model from values of 0.64, 0.56 and 0.68 has improved to values of 0.81, 0.88 and 0.91, respectively. The highest concentration of EC, with a value of 7050 μs/cm, is sampled in the areas of the east and northwest of the Ghaemshahr-juybar aquifer, which are classified in the CSI-Opt model as high and very high vulnerability levels. The highest concentration of TDS and SAR has been found in the east, northwest and northeast of the Ghaemshahr-juybar aquifer with a value of 4724 ppm for TDS and 14 mg/l for SAR that have been modeled in the CSI-Opt index as highly vulnerable areas. Eventually, CSI mapping can be used as an efficient tool in prioritizing in terms of the vulnerability to aquifer salinity, carrying out

Isotope and Hydrochemical Study of Seawater Intrusion into the Aquifers of a Coastal Zone in Cuba

Energy Technology Data Exchange (ETDEWEB)

Dapena, C.; Panarello, H. O.; Ducos, E. I.; Marban, L. [Instituto de Geocronologia y Geologia Isotopica (INGEIS, CONICET -UBA), Buenos Aires (Argentina); Peralta Vital, J. L.; Gil Castillo, R.; Leyva Bombuse, D. [Centro de Proteccion e Higiene de las Radiaciones (CPHR), La Habana (Cuba); Valdez, L. [Empresa de Investigaciones y Proyectos Hidraulicos Habana, La Habana (Cuba); Olivera Acosta, J. [Instituto de Geofisica y Astronomia. La Habana (Cuba)

2013-07-15

The Artemisa-Quivican Basin is located in the southern sector of the province of Havana, Cuba. This basin contains the most important aquifer of Havana province. It has a length of nearly 120 km and is 25 km in width. Recharge depends on the precipitation regime and rain infiltrates in a considerable proportion due to the intense development of karstic features. This aquifer is used for water supply to population, industry, and irrigation and is affected by over-exploitation and risk of contamination by saline sea intrusion. The main objective of this study is the isotope and chemical characterization of the aquifer and the delimitation of the area influenced by saline intrusion. Groundwater and river water are of the calcium bicarbonate type except those with evidence of mixture with saline water. Groundwater exhibits a variable proportion of mixture with seawater, indicating the presence of the saline intrusion. (author)

Effluent salinity of pipe drains and tube-wells : a case study from the Indus plain

NARCIS (Netherlands)

Kelleners, T.J.

2001-01-01

Keywords: anisotropy, aquifer, desalinization, effluent salinity, groundwater, irrigation, salt-water upconing, soil salinity, stream-function, subsurface drainage

Irrigated agriculture in arid and semi-arid zones often suffers from waterlogging and salinity problems.

Profitability Evaluation of a Hybrid Geothermal and CO2 Sequestration Project for a Coastal Hot Saline Aquifer.

Science.gov (United States)

Plaksina, Tatyana; Kanfar, Mohammed

2017-11-01

With growing interest in commercial projects involving industrial volume CO2 sequestration, a concern about proper containment and control over the gas plume becomes particularly prominent. In this study, we explore the potential of using a typical coastal geopressured hot saline aquifer for two commercial purposes. The first purpose is to harvest geothermal heat of the aquifer for electricity generation and/or direct use and the second one is to utilize the same rock volume for safe and controlled CO2 sequestration without interruption of heat production. To achieve these goals, we devised and economically evaluated a scheme that recovers operational and capital costs within first 4 years and yields positive internal rate of return of about 15% at the end of the operations. Using our strategic design of well placement and operational scheduling, we were able to achieve in our numerical simulation study the following results. First, the hot water production rates allowed to run a 30 MW organic Rankine cycle plant for 20 years. Second, during the last 10 years of operation we managed to inject into the same reservoir (volume of 0.8 x 109 m3) approximately 10 million ton of the supercritical gas. Third, decades of numerical monitoring the plume after the end of the operations showed that this large volume of CO2 is securely sequestrated inside the reservoir without compromising the caprock integrity.

Numerical Simulation of Multiphase Hydromechanical Processes Induced by CO2 Injection into Deep Saline Aquifers Simulation numérique des processus hydromécaniques polyphasiques provoqués par l’injection de CO2 dans des aquifères salins profonds

Directory of Open Access Journals (Sweden)

Goerke U.-J.

2011-02-01

Full Text Available In this paper, the conceptual modeling and the numerical simulation of two-phase flow during CO2 injection into deep saline aquifers is presented. The work focuses on isothermal short-term processes in the vicinity of the injection well. Governing differential equations are based on balance laws for mass and momentum, and completed by constitutive relations for the fluid and solid phases as well as their mutual interactions. Constraint conditions for the partial saturations and the pressure fractions of CO2 and brine are defined. To characterize the stress state in the solid matrix, the effective stress principle is applied. The coupled problem is solved using the inhouse scientific code OpenGeoSys (an open source finite element code and verified with benchmarks. Cet article présente le concept de la modélisation ainsi que la simulation numérique d’écoulement biphasé lors de l’injection de CO2 dans des aquifères salins profonds. L’étude se concentre sur des processus à court terme dans la proximité de puits d’injection dans les conditions isothermes. Les équations différentielles principales sont dérivées des équations de bilan de masse et de la quantité de mouvement, et elles sont complétées par des relations constitutives pour des phases solides et fluides ainsi que leur interaction. Les conditions de contrainte sont définies pour la saturation partielle, les fractions de pression de CO2 et l’eau salée. Pour caractériser l’état de contrainte dans la matrice solide, le principe de contrainte effective est appliqué. Le problème couplé considéré est résolu en utilisant le logiciel scientifique interne OpenGeoSys (un logiciel d’éléments finis libre d’accès et vérifié avec des exemples pour les processus concernés.

A correction for Dupuit-Forchheimer interface flow models of seawater intrusion in unconfined coastal aquifers

Science.gov (United States)

Koussis, Antonis D.; Mazi, Katerina; Riou, Fabien; Destouni, Georgia

2015-06-01

Interface flow models that use the Dupuit-Forchheimer (DF) approximation for assessing the freshwater lens and the seawater intrusion in coastal aquifers lack representation of the gap through which fresh groundwater discharges to the sea. In these models, the interface outcrops unrealistically at the same point as the free surface, is too shallow and intersects the aquifer base too far inland, thus overestimating an intruding seawater front. To correct this shortcoming of DF-type interface solutions for unconfined aquifers, we here adapt the outflow gap estimate of an analytical 2-D interface solution for infinitely thick aquifers to fit the 50%-salinity contour of variable-density solutions for finite-depth aquifers. We further improve the accuracy of the interface toe location predicted with depth-integrated DF interface solutions by ∼20% (relative to the 50%-salinity contour of variable-density solutions) by combining the outflow-gap adjusted aquifer depth at the sea with a transverse-dispersion adjusted density ratio (Pool and Carrera, 2011), appropriately modified for unconfined flow. The effectiveness of the combined correction is exemplified for two regional Mediterranean aquifers, the Israel Coastal and Nile Delta aquifers.

Sequestration of carbon in saline aquifers - mathematical and numerical analysis

Energy Technology Data Exchange (ETDEWEB)

Nordbotten, Jan Martin

2004-01-01

The work in this thesis focuses equally on two main topics. The set of these subjects deals with development of criteria for monotonicity of control volume methods. These methods are important and frequently used for solving the pressure equation arising in porous media flow. First we consider homogeneous parallelogram grids, and subsequently general logical Cartesian grids in heterogeneous media. This subject is concluded by the development of a new class of Multi Point Flux Approximation methods, motivated by the monotonicity results obtained. The second topic of this thesis is the development of analytical and semi- analytical solutions to the problem of leakage through abandoned wells. More specially, we look at a set of aquifers, separated by impermeable layers (aquicludes), where injection of water or CO{sub 2} takes place in some or all the aquifers. The aquifers and aquicludes are frequently penetrated by abandoned wells from oil exploration, and our problem consists of finding solutions to flow and leakage through these wells. The goal is to obtain expressions for leakage rates that may be evaluated quickly enough such that Monte Carlo realizations over statistical distributions of properties for abandoned wells can be performed. (author)

Map showing minimum depth to water in shallow aquifers (1963-72) in the Sugar House quadrangle, Salt Lake County, Utah

Science.gov (United States)

Mower, R.W.; Van Horn, Richard

1973-01-01

The depth to ground water in shallow aquifers in the Sugar Horse quadrangle ranges from zero in areas of springs and seeps to more than 10 feet beneath most of the area shown on the map. The depth to water differs from place to place because of irregular topography, and the varying capability of different rock materials to transmit water. Ground water also occurs under unconfined and confined conditions in deep aquifers beneath the Sugar Horse quadrangle, as shown by the block diagram and as described by Hely, Mower, and Harr (1971a, p. 17-111).

Insights from the salinity origins and interconnections of aquifers in a regional scale sedimentary aquifer system (Adour-Garonne district, SW France): Contributions of δ34S and δ18O from dissolved sulfates and the 87Sr/86Sr ratio

International Nuclear Information System (INIS)

Brenot, Agnès; Négrel, Philippe; Petelet-Giraud, Emmanuelle; Millot, Romain; Malcuit, Eline

2015-01-01

dissolved sulfates and the 87 Sr/ 86 Sr ratio, suggest that evaporite dissolution (both sulfate and halite) is the main process controlling the high salinity levels observed in the groundwater, explaining the spatial variations observed at the aquifer system scale. Isotopic tools also provide new information regarding the interconnections between aquifer layers, supporting the hypothesis that the Eocene aquifer system integrates groundwater from the Oligocene–Miocene aquifer through leakage effects. These new insights will likely help decision-makers adjust their choices when managing quality problems, in particular in the “mineralized area of the Entre-Deux-Mers,” where targeted groundwater wells used for drinking water display anomalous levels of critical substances

Hydrologic assessment of the shallow groundwater flow system beneath the Shinnecock Nation tribal lands, Suffolk County, New York

Science.gov (United States)

Noll, Michael L.; Rivera, Simonette L.; Busciolano, Ronald J.

2016-12-02

Defining the distribution and flow of shallow groundwater beneath the Shinnecock Nation tribal lands in Suffolk County, New York, is a crucial first step in identifying sources of potential contamination to the surficial aquifer and coastal ecosystems. The surficial or water table aquifer beneath the tribal lands is the primary source of potable water supply for at least 6 percent of the households on the tribal lands. Oyster fisheries and other marine ecosystems are critical to the livelihood of many residents living on the tribal lands, but are susceptible to contamination from groundwater entering the embayment from the surficial aquifer. Contamination of the surficial aquifer from flooding during intense coastal storms, nutrient loading from fertilizers, and septic effluent have been identified as potential sources of human and ecological health concerns on tribal lands.The U.S. Geological Survey (USGS) facilitated the installation of 17 water table wells on and adjacent to the tribal lands during March 2014. These wells were combined with other existing wells to create a 32-well water table monitoring network that was used to assess local hydrologic conditions. Survey-grade, global-navigation-satellite systems provided centimeter-level accuracy for positioning wellhead surveys. Water levels were measured by the USGS during May (spring) and November (fall) 2014 to evaluate seasonal effects on the water table. Water level measurements were made at high and low tide during May 2014 to identify potential effects on the water table caused by changes in tidal stage (tidal flux) in Shinnecock Bay. Water level contour maps indicate that the surficial aquifer is recharged by precipitation and upgradient groundwater flow that moves from the recharge zone located generally beneath Sunrise Highway, to the discharge zone beneath the tribal lands, and eventually discharges into the embayment, tidal creeks, and estuaries that bound the tribal lands to the east, south, and

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.

Profitability Evaluation of a Hybrid Geothermal and CO2 Sequestration Project for a Coastal Hot Saline Aquifer.

Directory of Open Access Journals (Sweden)

Plaksina Tatyana

2017-01-01

Full Text Available With growing interest in commercial projects involving industrial volume CO2 sequestration, a concern about proper containment and control over the gas plume becomes particularly prominent. In this study, we explore the potential of using a typical coastal geopressured hot saline aquifer for two commercial purposes. The first purpose is to harvest geothermal heat of the aquifer for electricity generation and/or direct use and the second one is to utilize the same rock volume for safe and controlled CO2 sequestration without interruption of heat production. To achieve these goals, we devised and economically evaluated a scheme that recovers operational and capital costs within first 4 years and yields positive internal rate of return of about 15% at the end of the operations. Using our strategic design of well placement and operational scheduling, we were able to achieve in our numerical simulation study the following results. First, the hot water production rates allowed to run a 30 MW organic Rankine cycle plant for 20 years. Second, during the last 10 years of operation we managed to inject into the same reservoir (volume of 0.8 x 109 m3 approximately 10 million ton of the supercritical gas. Third, decades of numerical monitoring the plume after the end of the operations showed that this large volume of CO2 is securely sequestrated inside the reservoir without compromising the caprock integrity.

Contribution of Isotopic Tools to the Numerical Simulation of the Mar del Plata Coastal Aquifer, Argentina

Energy Technology Data Exchange (ETDEWEB)

Bocanegra, E.; Martinez, D. E. [Instituto de Geologia de Costas y del Cuaternario, UNMDP (Argentina); Pool, M.; Carrera, J. [Instituto de Diagnostico Ambiental y Estudios del Agua, CSIC (Spain)

2013-07-15

Over-exploitation in the coastal aquifer in Mar del Plata, Argentina, led to a seawater intrusion process affecting groundwater by salinization. The aim of this paper is to show the contribution of isotopic techniques to generate the numerical flow and transport model of the Mar del Plata aquifer. On the basis of the hydrogeological conceptual model, a numerical model was constructed. It consists of a multilayer aquifer in the urban area with 2 layers separated by an aquitard and a monolayer aquifer in the rest of the basin. The isotopic difference recorded in groundwaters allow the identification of the origin of the recharge and the confirmation of the presence of the hydrogeological environments incorporated in the numerical model. Flow simulation reflects the evolution of piezometric heads. Chloride transport simulation represents the salinization process due to seawater intrusion and the subsequent backward movement of the interface due to the abandonment of salinized wells. The results of numerical simulation confirm the conceptual model and reproduce the impact of the adopted management strategies. (author)

Plume Migration of Different Carbon Dioxide Phases During Geological Storage in Deep Saline Aquifers

Directory of Open Access Journals (Sweden)

Chien-Hao Shen

2015-01-01

Full Text Available This study estimates the plume migration of mobile supercritical phase (flowing, aqueous phase (dissolved, and ionic phase CO2 (bicarbonate, and evaluates the spatial distribution of immobile supercritical phase (residual and mineral phase CO2 (carbonates when CO2 was sequestered. This utilized a simulation, in an anticline structure of a deep saline aquifer in the Tiechenshan (TCS field, Taiwan. All of the trapping mechanisms and different CO2 phases were studied using the fully coupled geochemical equation-of-state GEM compositional simulator. The mobile supercritical phase CO2 moved upward and then accumulated in the up-dip of the structure because of buoyancy. A large amount of immobile supercritical phase CO2 was formed at the rear of the moving plume where the imbibition process prevailed. Both the aqueous and ionic phase CO2 finally accumulated in the down-dip of the structure because of convection. The plume volume of aqueous phase CO2 was larger than that of the supercritical phase CO2, because the convection process increased vertical sweep efficiency. The up-dip of the structure was not the major location for mineralization, which is different from mobile supercritical phase CO2 accumulation.

Relationship of regional water quality to aquifer thermal energy storage

International Nuclear Information System (INIS)

Allen, R.D.; Raymond, J.R.

1990-01-01

Aquifer thermal energy storage (ATES) involves injection and withdrawal of temperature-conditioned water into and from a permeable water-bearing formation. The groundwater quality and associated geological characteristics were assessed as they may affect the feasibility of ATES system development in any hydrologic region. Seven physical and chemical mechanisms may decrease system efficiency: particulate plugging, chemical precipitation, clay mineral dispersion, piping corrosion, aquifer disaggregation, mineral oxidation, and the proliferation of biota. Factors affecting groundwater quality are pressure, temperature, pH, ion exchange, evaporation/transpiration, and commingling with diverse waters. Modeling with the MINTEQ code showed three potential reactions: precipitation of calcium carbonate at raised temperatures; solution of silica at raised temperature followed by precipitation at reduced temperatures; and oxidation/precipitation of iron compounds. Low concentrations of solutes are generally favorable for ATES. Near-surface waters in high precipitation regions are low in salinity. Groundwater recharged from fresh surface waters also has reduced salinity. Rocks least likely to react with groundwater are siliceous sandstones, regoliths, and metamorphic rocks. On the basis of known aquifer hydrology, ten US water resource regions are candidates for selected exploration and development, all characterized by extensive silica-rich aquifers

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

Efficient parallel simulation of CO2 geologic sequestration in saline aquifers

International Nuclear Information System (INIS)

Zhang, Keni; Doughty, Christine; Wu, Yu-Shu; Pruess, Karsten

2007-01-01

An efficient parallel simulator for large-scale, long-term CO2 geologic sequestration in saline aquifers has been developed. The parallel simulator is a three-dimensional, fully implicit model that solves large, sparse linear systems arising from discretization of the partial differential equations for mass and energy balance in porous and fractured media. The simulator is based on the ECO2N module of the TOUGH2code and inherits all the process capabilities of the single-CPU TOUGH2code, including a comprehensive description of the thermodynamics and thermophysical properties of H2O-NaCl- CO2 mixtures, modeling single and/or two-phase isothermal or non-isothermal flow processes, two-phase mixtures, fluid phases appearing or disappearing, as well as salt precipitation or dissolution. The new parallel simulator uses MPI for parallel implementation, the METIS software package for simulation domain partitioning, and the iterative parallel linear solver package Aztec for solving linear equations by multiple processors. In addition, the parallel simulator has been implemented with an efficient communication scheme. Test examples show that a linear or super-linear speedup can be obtained on Linux clusters as well as on supercomputers. Because of the significant improvement in both simulation time and memory requirement, the new simulator provides a powerful tool for tackling larger scale and more complex problems than can be solved by single-CPU codes. A high-resolution simulation example is presented that models buoyant convection, induced by a small increase in brine density caused by dissolution of CO2

Characterization of mechanisms and processes of groundwater salinization in irrigated coastal area using statistics, GIS, and hydrogeochemical investigations.

Science.gov (United States)

Bouzourra, Hazar; Bouhlila, Rachida; Elango, L; Slama, Fairouz; Ouslati, Naceur

2015-02-01

Coastal aquifers are at threat of salinization in most parts of the world. This study was carried out in coastal shallow aquifers of Aousja-Ghar El Melh and Kalâat el Andalous, northeastern of Tunisia with an objective to identify sources and processes of groundwater salinization. Groundwater samples were collected from 42 shallow dug wells during July and September 2007. Chemical parameters such as Na(+), Ca(2+), Mg(2+), K(+), Cl(-), SO4 (2-), HCO3 (-), NO3 (-), Br(-), and F(-) were analyzed. The combination of hydrogeochemical, statistical, and GIS approaches was used to understand and to identify the main sources of salinization and contamination of these shallow coastal aquifers as follows: (i) water-rock interaction, (ii) evapotranspiration, (iii) saltwater is started to intrude before 1972 and it is still intruding continuously, (iv) irrigation return flow, (v) sea aerosol spray, and finally, (vi) agricultural fertilizers. During 2005/2006, the overexploitation of the renewable water resources of aquifers caused saline water intrusion. In 2007, the freshening of a brackish-saline groundwater occurred under natural recharge conditions by Ca-HCO3 meteoric freshwater. The cationic exchange processes are occurred at fresh-saline interfaces of mixtures along the hydraulic gradient. The sulfate reduction process and the neo-formation of clays minerals characterize the hypersaline coastal Sebkha environments. Evaporation tends to increase the concentrations of solutes in groundwater from the recharge areas to the discharge areas and leads to precipitate carbonate and sulfate minerals.

Experimental investigation of CO2-brine-rock interactions at elevated temperature and pressure: Implications for CO2 sequestration in deep-saline aquifers

Science.gov (United States)

Rosenbauer, R.J.; Koksalan, T.; Palandri, J.L.

2005-01-01

Deep-saline aquifers are potential repositories for excess CO2, currently being emitted to the atmosphere from anthropogenic activities, but the reactivity of supercritical CO2 with host aquifer fluids and formation minerals needs to be understood. Experiments reacting supercritical CO2 with natural and synthetic brines in the presence and absence of limestone and plagioclase-rich arkosic sandstone showed that the reaction of CO2-saturated brine with limestone results in compositional, mineralogical, and porosity changes in the aquifer fluid and rock that are dependent on initial brine composition, especially dissolved calcium and sulfate. Experiments reacting CO2-saturated, low-sulfate brine with limestone dissolved 10% of the original calcite and increased rock porosity by 2.6%. Experiments reacting high-sulfate brine with limestone, both in the presence and absence of supercritical CO2, were characterized by the precipitation of anhydrite, dolomitization of the limestone, and a final decrease in porosity of 4.5%. However, based on favorable initial porosity changes of about 15% due to the dissolution of calcite, the combination of CO2 co-injection with other mitigation strategies might help alleviate some of the well-bore scale and formation-plugging problems near the injection zone of a brine disposal well in Paradox Valley, Colorado, as well as provide a repository for CO2. Experiments showed that the solubility of CO2 is enhanced in brine in the presence of limestone by 9% at 25 ??C and 6% at 120 ??C and 200 bar relative to the brine itself. The solubility of CO2 is enhanced also in brine in the presence of arkosic sandstone by 5% at 120 ??C and 300 bar. The storage of CO 2 in limestone aquifers is limited to only ionic and hydraulic trapping. However, brine reacted with supercritical CO2 and arkose yielded fixation and sequestration of CO2 in carbonate mineral phases. Brine desiccation was observed in all experiments containing a discrete CO2 phase

Ground-water quality and geochemistry, Carson Desert, western Nevada

Science.gov (United States)

Lico, Michael S.; Seiler, R.L.

1994-01-01

Aquifers in the Carson Desert are the primary source of drinking water, which is highly variable in chemical composition. In the shallow basin-fill aquifers, water chemistyr varies from a dilute calcium bicarbonate-dominated water beneath the irrigated areas to a saline sodium chloride- dominated water beneath unirrigated areas. Water samples from the shallow aquifers commonly have dissolved solids, chloride, magnesium, sulfate, arsenic, and manganese concentrations that exceed State of Nevada drinking-water standards. Water in the intermediante basin-fill aquifers is a dilute sodium bicarbonate type in the Fallon area and a distinctly more saline sodium chloride type in the Soda Lake-Upsal Hogback area. Dissolved solids, chloride, arsenic, fluoride, and manganese concen- trations commonly exceed drinking-water standards. The basalt aquifer contains a dilute sodium bicarbonate chloride water. Arsenic concentrations exceed standards in all sampled wells. The concen- trations of major constituents in ground water beneath the southern Carson Desert are the result of evapotranspiration and natural geochemical reactions with minerals derived mostly from igneous rocks. Water with higher concentrations of iron and manganese is near thermodynamic equilibrium with siderite and rhodochrosite and indicates that these elements may be limited by the solubility of their respective carbonate minerals. Naturally occurring radionuclides (uranium and radon-222) are present in ground water from the Carson Desert in concen- tratons higher than proposed drinking-water standards. High uranium concentrations in the shallow aquifers may be caused by evaporative concentration and the release of uranium during dissolution of iron and manganese oxides or the oxidation of sedimentary organic matter that typically has elevated uranium concentrations. Ground water in the Carson Desert does not appear to have be contaminated by synthetic organic chemicals.

Identification of palaeo-seawater intrusion in groundwater using minor ions in a semi-confined aquifer of the Río de la Plata littoral (Argentina)

Energy Technology Data Exchange (ETDEWEB)

Santucci, L., E-mail: eleocarol@fcnym.unlp.edu.ar [Centro de Investigaciones Geológicas (CIG), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) - Universidad Nacional de La Plata - UNLP, Calle 64 y Diag. 113, 1900 La Plata, Buenos Aires (Argentina); Carol, E. [Centro de Investigaciones Geológicas (CIG), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) - Universidad Nacional de La Plata - UNLP, Calle 64 y Diag. 113, 1900 La Plata, Buenos Aires (Argentina); Kruse, E. [Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Cátedra de Hidrología General de la Facultad de Ciencias Naturales y Museo, Universidad Nacional de La Plata (UNLP), Calle 64 #3, 1900 La Plata, Buenos Aires (Argentina)

2016-10-01

The hydrochemistry of minor elements and traces such as bromide, lithium, strontium, uranium and selenium, together with the chemical analysis of major ions, has been used in the study of salinization process. This process occurs in a semi-confined aquifer that corresponds to a Pliocene–Pleistocene fluvial environment. The semi-confined aquifer is located in the littoral of the cities of Ensenada and Berisso, in the region of the middle Río de la Plata estuary, Argentina. Groundwater salinization was detected in the semi-confined aquifer in the coastal plain area, with salt contents that increase from the loess plain towards the river. The content of major ions that predominate in sea water (Cl{sup −}, Na{sup +} and Mg{sup 2+}), as well as the Cl{sup −}/Br{sup −} and U vs. Cl{sup −} ratios, demonstrates that such salinization is related to sea water, which shows no correspondence with estuary water. In the salinized area, Li, Sr and Se enrichments occur, and are used as tracers of the average time that a substance remains in solution in sea water in the aquifer. The study of such minor ions together with the geological evolution of the area made it possible to recognize that the salt water in the semi-confined aquifer corresponds to a palaeo-intrusion of sea water associated with the Pleistocene–Holocene ingressions caused by the climate changes occurring during the Quaternary. - Highlights: • The semi-confined aquifer in a sector of the Río de la Plata estuary is salinized. • Saline content is higher in the aquifer than in the estuary. • Minor elements indicate the occurrence of palaeo-seawater intrusion. • Palaeo-seawater intrusion may be associated with interglacial fluctuations.

Identification of palaeo-seawater intrusion in groundwater using minor ions in a semi-confined aquifer of the Río de la Plata littoral (Argentina)

International Nuclear Information System (INIS)

Santucci, L.; Carol, E.; Kruse, E.

2016-01-01

The hydrochemistry of minor elements and traces such as bromide, lithium, strontium, uranium and selenium, together with the chemical analysis of major ions, has been used in the study of salinization process. This process occurs in a semi-confined aquifer that corresponds to a Pliocene–Pleistocene fluvial environment. The semi-confined aquifer is located in the littoral of the cities of Ensenada and Berisso, in the region of the middle Río de la Plata estuary, Argentina. Groundwater salinization was detected in the semi-confined aquifer in the coastal plain area, with salt contents that increase from the loess plain towards the river. The content of major ions that predominate in sea water (Cl"−, Na"+ and Mg"2"+), as well as the Cl"−/Br"− and U vs. Cl"− ratios, demonstrates that such salinization is related to sea water, which shows no correspondence with estuary water. In the salinized area, Li, Sr and Se enrichments occur, and are used as tracers of the average time that a substance remains in solution in sea water in the aquifer. The study of such minor ions together with the geological evolution of the area made it possible to recognize that the salt water in the semi-confined aquifer corresponds to a palaeo-intrusion of sea water associated with the Pleistocene–Holocene ingressions caused by the climate changes occurring during the Quaternary. - Highlights: • The semi-confined aquifer in a sector of the Río de la Plata estuary is salinized. • Saline content is higher in the aquifer than in the estuary. • Minor elements indicate the occurrence of palaeo-seawater intrusion. • Palaeo-seawater intrusion may be associated with interglacial fluctuations.

Saltwater intrusion in the surficial aquifer system of the Big Cypress Basin, southwest Florida, and a proposed plan for improved salinity monitoring

Science.gov (United States)

Prinos, Scott T.

2013-01-01

The installation of drainage canals, poorly cased wells, and water-supply withdrawals have led to saltwater intrusion in the primary water-use aquifers in southwest Florida. Increasing population and water use have exacerbated this problem. Installation of water-control structures, well-plugging projects, and regulation of water use have slowed saltwater intrusion, but the chloride concentration of samples from some of the monitoring wells in this area indicates that saltwater intrusion continues to occur. In addition, rising sea level could increase the rate and extent of saltwater intrusion. The existing saltwater intrusion monitoring network was examined and found to lack the necessary organization, spatial distribution, and design to properly evaluate saltwater intrusion. The most recent hydrogeologic framework of southwest Florida indicates that some wells may be open to multiple aquifers or have an incorrect aquifer designation. Some of the sampling methods being used could result in poor-quality data. Some older wells are badly corroded, obstructed, or damaged and may not yield useable samples. Saltwater in some of the canals is in close proximity to coastal well fields. In some instances, saltwater occasionally occurs upstream from coastal salinity control structures. These factors lead to an incomplete understanding of the extent and threat of saltwater intrusion in southwest Florida. A proposed plan to improve the saltwater intrusion monitoring network in the South Florida Water Management District’s Big Cypress Basin describes improvements in (1) network management, (2) quality assurance, (3) documentation, (4) training, and (5) data accessibility. The plan describes improvements to hydrostratigraphic and geospatial network coverage that can be accomplished using additional monitoring, surface geophysical surveys, and borehole geophysical logging. Sampling methods and improvements to monitoring well design are described in detail. Geochemical analyses

Water quality considerations on the rise as the use of managed aquifer recharge systems widens

NARCIS (Netherlands)

Hartog, Niels; Stuyfzand, Pieter J.

2017-01-01

Managed Aquifer Recharge (MAR) is a promising method of increasing water availability in water stressed areas by subsurface infiltration and storage, to overcome periods of drought, and to stabilize or even reverse salinization of coastal aquifers. Moreover, MAR could be a key technique in making

Phreatophytes under stress: transpiration and stomatal conductance of saltcedar (Tamarix spp.) in a high-salinity environment

Science.gov (United States)

Glenn, Edward P.; Nagler, Pamela L.; Morino, Kiyomi; Hultine, Kevin

2013-01-01

Background and aims: We sought to understand the environmental constraints on an arid-zone riparian phreatophtye, saltcedar (Tamarix ramosissima and related species and hybrids), growing over a brackish aquifer along the Colorado River in the western U.S. Depth to groundwater, meteorological factors, salinity and soil hydraulic properties were compared at stress and non-stressed sites that differed in salinity of the aquifer, soil properties and water use characteristics, to identify the factors depressing water use at the stress site.

Water quality considerations on the rise as the use of managed aquifer recharge systems widens

NARCIS (Netherlands)

Hartog, Niels; Stuijfzand, Pieter

2017-01-01

Managed Aquifer Recharge (MAR) is a promising method of increasing water availability in water stressed areas by subsurface infiltration and storage, to overcome periods of drought, and to stabilize or even reverse salinization of coastal aquifers. Moreover, MAR could be a key technique in making

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

Reactions and reaction rates in the regional aquifer beneath the Pajarito Plateau, north-central New Mexico, USA

Science.gov (United States)

Hereford, Anne G.; Keating, Elizabeth H.; Guthrie, George D.; Zhu, Chen

2007-05-01

Reactions and reaction rates within aquifers are fundamental components of critical hydrological processes. However, reactions simulated in laboratory experiments typically demonstrate rates that are much faster than those observed in the field. Therefore, it is necessary to conduct more reaction rate analyses in natural settings. This study of geochemical reactions in the regional aquifer in the Pajarito Plateau near Los Alamos, New Mexico combines modeling with petrographic assessment to further knowledge and understanding of complex natural hydrologic systems. Groundwater geochemistry shows marked evolution along assumed flow paths. The flow path chosen for this study was evaluated using inverse mass balance modeling to calculate the mass transfer. X-ray diffraction and field emission gun scanning electron microscopy were used to identify possible reactants and products. Considering the mineralogy of the aquifer and saturation indices for the regional water refined initial interpretations. Calculations yielded dissolution rates for plagioclase on the order of 10-15 mol s-1 m-2 and for K-feldspar on the order of 10-17 mol s-1 m-2, orders of magnitude slower than laboratory rates. While these rates agree with other aquifer studies, they must be considered in the light of the uncertainty associated with geometric surface area estimates, 14C ages, and aquifer properties.

Numerical simulation methods applied to injection and storage of CO{sub 2} in saline aquifers; Metodos de simulacion numerica aplicados a la inyeccion y almacenamiento de CO{sub 2} en formaciones salinas

Energy Technology Data Exchange (ETDEWEB)

Arjona Garcia-Borreguero, J.; Rodriguez Pons-Esparver, R.; Iglesias Lopez, A.

2015-07-01

One of the Climate Change mitigation proposals suggested by the IPCC (Intergovernmental Panel on Climate Change) in its Synthesis Report 2007 involves the launch of applications for capturing and storing carbon dioxide, existing three different geological structures suitable for gas storage: oil and gas depleted reservoirs, useless coal layers and deep saline structures. In case of deep saline structures, the main problem to prepare a study of CO{sub 2} storage is the difficulty of obtaining geological data for some selected structure with characteristics that could be suitable for injection and gas storage. According to this situation, the solution to analyze the feasibility of a storage project in a geological structure will need numerical simulation from a 3D terrain model. Numerical methods allow the simulation of the carbon dioxide filling in saline structures from a well, used to inject gas with a particular flow. This paper presents a methodology to address the modeling and simulation process of CO{sub 2} injection into deep saline aquifers. (Author)

Improved aquifer characterization and the optimization of the design of brackish groundwater desalination systems

KAUST Repository

Malivaa, Robert G.

2011-07-01

Many water scarce regions possess brackish-water resources that can be desalted to provide alternative water supplies. Brackish groundwater desalination by reverse osmosis (RO) is less expensive than seawater systems because of reduced energy and pretreatment requirements and lesser volumes of concentrate that require disposal. Development of brackish groundwater wellfields include the same hydraulic issues that affect conventional freshwater wellfields. Managing well interference and prevention of adverse impacts such as land subsidence are important concerns. RO systems are designed to treat water whose composition falls within a system-specific envelope of salinities and ion concentrations. A fundamental requirement for the design of brackish groundwater RO systems is prediction of the produced water chemistry at both the start of pumping and after 10-20 years of operation. Density-dependent solute-transport modeling is thus an integral component of the design of brackish groundwater RO systems. The accuracy of groundwater models is dependent upon the quality of the hydrogeological data upon which they are based. Key elements of the aquifer characterization are the determination of the three-dimensional distribution of salinity within the aquifer and the evaluation of aquifer heterogeneity with respect to hydraulic conductivity. It is necessary to know from where in a pumped aquifer (or aquifer zone) water is being produced and the contribution of vertical flow to the produced water. Unexpected, excessive vertical migration (up-coning) of waters that are more saline has adversely impacted some RO systems because the salinity of the water delivered to the system exceeded the system design parameters. Improved aquifer characterization is possible using advanced geophysical techniques, which can, in turn, lead to more accurate solute-transport models. Advanced borehole geophysical logs, such as nuclear magnetic resonance, were run as part of the exploratory test

Application of the top specified boundary layer (TSBL) approximation to initial characterization of an inland aquifer mineralization: 2. Seepage of saltwater through semi-confining layers

Science.gov (United States)

Rubin, H.; Buddemeier, R.W.

1998-01-01

This paper presents a generalized basic study that addresses practical needs for an understanding of the major mechanisms involved in the mineralization of groundwater in the Great Bend Prairie aquifer in south- central Kansas. This Quaternary alluvial aquifer and associated surface waters are subject to contamination by saltwater, which in some areas seeps from the deeper Permian bedrock formation into the overlying freshwater aquifer through semiconfining layers. A simplified conceptual model is adopted. It incorporates the freshwater aquifer whose bottom is comprised of a semiconfining layer through which a hydrologically minor but geochemically important saline water discharge seeps into the aquifer. A hierarchy of approximate approaches is considered to analyze the mineralization processes taking place in the aquifer. The recently developed top specified boundary layer (TSBL) approach is very convenient to use for the initial characterization of these processes, and is further adapted to characterization of head-driven seepage through semi-confining layers. TSBL calculations indicate that the seeping saline water may create two distinct new zones in the aquifer: (1) a completely saline zone (CSZ) adjacent to the semiconfining bottom of the aquifer, and (2) a transition zone (TZ) which develops between the CSZ and the freshwater zone. Some possible scenarios associated with the various mineralization patterns are analyzed and discussed.

Brine/CO2 Interfacial Properties and Effects on CO2 Storage in Deep Saline Aquifers Propriétés interfaciales saumure/CO2 et effets sur le stockage du CO2 dans des aquifères salins profonds

Directory of Open Access Journals (Sweden)

Chalbaud C.

2010-05-01

Full Text Available It has been long recognized that interfacial interactions (interfacial tension, wettability, capillarity and interfacial mass transfer govern fluid distribution and behaviour in porous media. Therefore the interfacial interactions between CO2, brine and reservoir oil and/or gas have an important influence on the effectiveness of any CO2 storage operation. There is a lack of experimental data related to interfacial properties for all the geological storage options (oil & gas reservoirs, coalbeds, deep saline aquifers. In the case of deep saline aquifers, there is a gap in data and knowledge of brine-CO2 interfacial properties at storage conditions. More specifically, experimental interfacial tension values and experimental tests in porous media are necessary to better understand the wettability evolution as a function of thermodynamic conditions and it’s effects on fluid flow in the porous media. In this paper, a complete set of experimental values of brine-CO2 Interfaciale Tension (IFT at pressure, temperature and salt concentration conditions representative of those of a CO2 storage operation. A correlation is derived from experimental data published in a companion paper [Chalbaud C., Robin M., Lombard J.-M., Egermann P., Bertin H. (2009 Interfacial Tension Measurements and Wettability Evaluation for Geological CO2 Storage, Adv. Water Resour. 32, 1, 1-109] to model IFT values. This paper pays particular attention to coreflooding experiments showing that the CO2 partially wets the surface in a Intermediate-Wet (IW or Oil-Wet (OW limestone rock. This wetting behavior of CO2 is coherent with observations at the pore scale in glass micromodels and presents a negative impact on the storage capacity of a given site. Il est admis depuis longtemps que les propriétés interfaciales (tension interfaciale, mouillabilité, capillarité et transfert de masse régissent la distribution et le comportement des fluides au sein des milieux poreux. Par cons

Relationships of stable isotopes, water-rock interaction and salinization in fractured aquifers, Petrolina region, Pernambuco State, Brazil

Energy Technology Data Exchange (ETDEWEB)

Silva, Priscila Sousa, E-mail: priscila.silva@cprm.gov.br [Serviço Geológico do Brasil (CPRM), Manaus, AM (Brazil); Campos, José Eloi Guimarães; Cunha, Luciano Soares; Mancini, Luís Henrique, E-mail: eloi@unb.br, E-mail: lucianosc@unb.br, E-mail: lmancini@unb.br [Universidade de Brasília (UnB), Brasília, DF (Brazil)

2018-01-15

The Petrolina County, Pernambuco State, Brazil, presents specificities that make it unique from a hydrogeological point of view. Water resource scarcity is both a quantitative and qualitative issue. The climate is classified as semiarid, having low precipitation, along with high temperatures and evapotranspiration rates. Aquifer zones are related to low connected fractures resulting in a restricted water flow in the aquifer. The recharge is limited and the groundwater salinity is high. Stable isotope analyses of H and O were developed in groundwater samples (with different electrical conductivity) and surface water collected in a bypass channel flowing from the São Francisco River. The results were plotted in a δD ‰ versus δ{sup 18}O ‰ graph along with the curves of the global and local meteoric water line. Groundwater samples showed unexpected results showing a lighter sign pattern when compared to the meteoric waters. More negative δD and δ{sup 18}O values indicate an enrichment in light isotopes, which show that this process is not influenced by surface processes, where the enrichment occurs in heavy isotopes due to evaporation. The isotopic signature observed is interpreted either as resulting from the water-rock interaction, or as resulting from recharge from paleo rains. The waters are old and show restricted flow. So the water-rock contact time is extended. In the rock weathering processes, through the hydration of feldspars, there is preferential assimilation of heavy isotopes at the expense of the lighter ones that remain in the water. Analyses of the {sup 87}Sr/{sup 86}Sr ratio and isotopic groundwater dating assist in the interpretations. (author)

Modeling the Effects of Storm Surge from Hurricane Jeanne on Saltwater Intrusion into the Surficial Aquifer, East-Central Florida (USA)

Science.gov (United States)

Xiao, H.; Wang, D.; Hagen, S. C.; Medeiros, S. C.; Hall, C. R.

2017-12-01

Saltwater intrusion (SWI) that has been widely recognized as a detrimental issue causing the deterioration of coastal aquifer water quality and degradation of coastal ecosystems. While it is widely recognized that SWI is exacerbated worldwide due to global sea-level rise, we show that increased SWI from tropical cyclones under climate change is also a concern. In the Cape Canaveral Barrier Island Complex (CCBIC) located in east-central Florida, the salinity level of the surficial aquifer is of great importance to maintain a bio-diverse ecosystem and to support the survival of various vegetation species. Climate change induced SWI into the surficial aquifer can lead to reduction of freshwater storage and alteration of the distribution and productivity of vegetation communities. In this study, a three-dimensional variable-density SEAWAT model is developed and calibrated to investigate the spatial and temporal variation of salinity level in the surficial aquifer of CCBIC. We link the SEAWAT model to surge model data to examine the effects of storm surge from Hurricane Jeanne. Simulation results indicate that the surficial aquifer salinity level increases significantly right after the occurrence of storm surge because of high aquifer permeability and rapid infiltration and diffusion of the overtopping saltwater, while the surficial aquifer salinity level begins to decrease after the fresh groundwater recharge from the storm's rainfall. The tropical storm precipitation generates an effective hydraulic barrier further impeding SWI and providing seaward freshwater discharge for saltwater dilution and flushing. To counteract the catastrophic effects of storm surge, this natural remediation process may take at least 15-20 years or even several decades. These simulation results contribute to ongoing research focusing on forecasting regional vegetation community responses to climate change, and are expected to provide a useful reference for climate change adaptation planning

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

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.

Hydrogeochemical effects of groundwater mining of the Sierra de Crevillente Aquifer (Alicante, Spain)

Science.gov (United States)

Pulido-Bosch, A.; Morell, I.; Andreu, J. M.

1995-12-01

The groundwater mining of the Crevillente aquifer (southeastern Spain) has resulted in the progressive deterioration of water quality, with particularly significant increases in chloride, sulfate, and sodium. The possibility of a vertical hydrochemical zoning is deduced that would require examining the importance of the geometry and lithology (evaporitic materials) in the salinization process. The time of water-rock contact (residence time) and dilution by infiltration of rainwater also influences the hydrogeochemistry of the aquifer. The hydrochemical data are useful in defining the conceptual model of the aquifer, completely karstified with relative homogeneity.

Microbial diversity and impact on carbonate geochemistry across a changing geochemical gradient in a karst aquifer.

Science.gov (United States)

Gray, Cassie J; Engel, Annette S

2013-02-01

Although microbes are known to influence karst (carbonate) aquifer ecosystem-level processes, comparatively little information is available regarding the diversity of microbial activities that could influence water quality and geological modification. To assess microbial diversity in the context of aquifer geochemistry, we coupled 16S rRNA Sanger sequencing and 454 tag pyrosequencing to in situ microcosm experiments from wells that cross the transition from fresh to saline and sulfidic water in the Edwards Aquifer of central Texas, one of the largest karst aquifers in the United States. The distribution of microbial groups across the transition zone correlated with dissolved oxygen and sulfide concentration, and significant variations in community composition were explained by local carbonate geochemistry, specifically calcium concentration and alkalinity. The waters were supersaturated with respect to prevalent aquifer minerals, calcite and dolomite, but in situ microcosm experiments containing these minerals revealed significant mass loss from dissolution when colonized by microbes. Despite differences in cell density on the experimental surfaces, carbonate loss was greater from freshwater wells than saline, sulfidic wells. However, as cell density increased, which was correlated to and controlled by local geochemistry, dissolution rates decreased. Surface colonization by metabolically active cells promotes dissolution by creating local disequilibria between bulk aquifer fluids and mineral surfaces, but this also controls rates of karst aquifer modification. These results expand our understanding of microbial diversity in karst aquifers and emphasize the importance of evaluating active microbial processes that could affect carbonate weathering in the subsurface.

Brine migration resulting from CO2 injection into saline aquifers – An approach to risk estimation including various levels of uncertainty

DEFF Research Database (Denmark)

Walter, Lena; Binning, Philip John; Oladyshkin, Sergey

2012-01-01

resulting from displaced brine. Quantifying risk on the basis of numerical simulations requires consideration of different kinds of uncertainties and this study considers both, scenario uncertainty and statistical uncertainty. Addressing scenario uncertainty involves expert opinion on relevant geological......Comprehensive risk assessment is a major task for large-scale projects such as geological storage of CO2. Basic hazards are damage to the integrity of caprocks, leakage of CO2, or reduction of groundwater quality due to intrusion of fluids. This study focuses on salinization of freshwater aquifers...... for large-scale 3D models including complex physics. Therefore, we apply a model reduction based on arbitrary polynomial chaos expansion combined with probabilistic collocation method. It is shown that, dependent on data availability, both types of uncertainty can be equally significant. The presented study...

Simulation of Coupled Processes of Flow, Transport, and Storage of CO₂ in Saline Aquifers

Energy Technology Data Exchange (ETDEWEB)

Wu, Yu-Shu [Colorado School of Mines, Golden, CO (United States); Chen, Zizhong [Univ. of California, Riverside, CA (United States); Kazemi, Hossein [Colorado School of Mines, Golden, CO (United States); Yin, Xiaolong [Colorado School of Mines, Golden, CO (United States); Pruess, Karsten [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Oldenburg, Curt [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Winterfeld, Philip [Colorado School of Mines, Golden, CO (United States); Zhang, Ronglei [Colorado School of Mines, Golden, CO (United States)

2014-09-30

This report is the final scientific one for the award DE- FE0000988 entitled “Simulation of Coupled Processes of Flow, Transport, and Storage of CO₂ in Saline Aquifers.” The work has been divided into six tasks. In task, “Development of a Three-Phase Non-Isothermal CO₂ Flow Module,” we developed a fluid property module for brine-CO₂ mixtures designed to handle all possible phase combinations of aqueous phase, sub-critical liquid and gaseous CO₂, supercritical CO₂, and solid salt. The thermodynamic and thermophysical properties of brine-CO₂ mixtures (density, viscosity, and specific enthalpy of fluid phases; partitioning of mass components among the different phases) use the same correlations as an earlier fluid property module that does not distinguish between gaseous and liquid CO₂-rich phases. We verified the fluid property module using two leakage scenarios, one that involves CO₂ migration up a blind fault and subsequent accumulation in a secondary “parasitic” reservoir at shallower depth, and another investigating leakage of CO₂ from a deep storage reservoir along a vertical fault zone. In task, “Development of a Rock Mechanical Module,” we developed a massively parallel reservoir simulator for modeling THM processes in porous media brine aquifers. We derived, from the fundamental equations describing deformation of porous elastic media, a momentum conservation equation relating mean stress, pressure, and temperature, and incorporated it alongside the mass and energy conservation equations from the TOUGH2 formulation, the starting point for the simulator. In addition, rock properties, namely permeability and porosity, are functions of effective stress and other variables that are obtained from the literature. We verified the simulator formulation and numerical implementation using analytical solutions and example problems from the literature. For

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.

Hydrogeological study of the aquifer system of the northern Sahara in the Algero-Tunisian border: A case study of Oued Souf region

Science.gov (United States)

Halassa, Younes; Zeddouri, Aziez; Mouhamadou, Ould Babasy; Kechiched, Rabah; Benhamida, Abdeldjebbar Slimane

2018-05-01

The aquifer system in The Algero-Tunisian border and Chotts region is mainly composed of two aquifers: The first is the Complex Terminal (CT) and the second is the Intercalary aquifer (CI). This study aims the identification and spatial evolution of factors that controlling the water quality in the Complex Terminal aquifer (CT) in the Chotts region (Oued Souf region - Southeastern of Algeria). The concentration of major elements, temperature, pH and salinity were monitored during 2015 in 34 wells from the CT aquifer. The geological, geophysical, hydrogeological and hydrochemical methods were applied in order to carried out a model for the investigated aquifer system and to characterize the hydrogeological and the geochemical behavior, as well as the geometrical and the lithological configuration. Multivariate statistical analyses such as Principal Component Analysis (PCA) were also used for the treatment of several data. Results show that the salinity follows the same regional distribution of Chloride, Sodium, Magnesium, Sulfate and Calcium. Note that the salinity shows low contents in the upstream part of investigated region suggesting restricted dissolution of salts. Hydro-chemical study and saturation indexes highlight the dominance of the dissolution and the precipitation of calcite, dolomite, anhydrite, gypsum and halite. The PCA analysis indicates that Na+, Cl-, Ca2+, Mg2+, SO42- and K+ variables that influence the water mineralization.

Stressed aquifers in the Lower Segura basin and the Vinalopó basin in Easter Spain

Directory of Open Access Journals (Sweden)

Andrés Sahuquillo

2016-01-01

Full Text Available The carbonate aquifers of the Lower Segura Basin and the Vinalopó basin, along with some other granular aquifers are being exploited well above its average recharge for almost half a century. That causes a continuous decline of groundwater levels in most of the region, up to 5m/year in some cases and more than 300m from their initial situation in some areas, thus increasing the cost of groundwater pumping. The drop in levels produced the drying of springs and wetlands and increased salinity in some areas caused by the presence of saline formations. Against these problems is the increase in wealth created by the availability of water since the beginning of the intense exploitation of aquifers. The Water Framework Directive requires that aquifers being by 2015 in good quantitative and qualitative conditions, which is not possible, and neither would be delaying this date several decades. Simple analyses indicate that even eliminating pumping; groundwater would take between 100 and 1000years to recover. Several methods have been used for determining groundwater recharge and mathematical models that reproduce aquifer’s behaviour and could be used as valid tools for its management. The role that aquifers can play in the water resource management is discussed.

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

. Although the part of the lower Great Miami River Buried Valley Aquifer System where the Hamilton North Well Field is located is semiconfined, unconfined, or locally confined and not directly connected to the Great Miami River, the discontinuity of the clay/till layers beneath the river indicates that other, deeper parts of the aquifer system may be directly connected to the Great Miami River.

The study of coastal groundwater depth and salinity variation using time-series analysis

International Nuclear Information System (INIS)

Tularam, G.A.; Keeler, H.P.

2006-01-01

A time-series approach is applied to study and model tidal intrusion into coastal aquifers. The authors examine the effect of tidal behaviour on groundwater level and salinity intrusion for the coastal Brisbane region using auto-correlation and spectral analyses. The results show a close relationship between tidal behaviour, groundwater depth and salinity levels for the Brisbane coast. The known effect can be quantified and incorporated into new models in order to more accurately map salinity intrusion into coastal groundwater table

Isotopic discontinuities in ground water beneath Yucca Mountain, Nevada

International Nuclear Information System (INIS)

Stuckless, J.S.; Whelan, J.F.; Steinkampf, W.C.

1991-01-01

Analytical data for stable isotopes in ground water from beneath Yucca Mountain, when examined in map view, show areal patterns of heterogeneity that can be interpreted in terms of mixing of at least three end members. One end member must be isotopically heavy in terms of hydrogen and oxygen and have a young apparent 14 C age such as water found at the north end of Yucca Mountain beneath Fortymile Wash. A second end member must contain isotopically heavy carbon and have an old apparent 14 C age such as water from the Paleozoic aquifer. The third end member cannot be tightly defined. It must be isotopically lighter than the first with respect of hydrogen and oxygen and be intermediate to the first and second end members with respect to both apparent 14 C age and δ 13 C. The variable isotopic compositions of hydrogen and oxygen indicate that two of the end members are waters, but the variable carbon isotopic composition could represent either a third water end member or reaction of water with a carbon-bearing solids such as calcite. 15 refs., 4 figs., 1 tab

Thermo-hydro-chemical performance assessment of CO2 storage in saline aquifer

International Nuclear Information System (INIS)

Le Gallo, Y.; Trenty, L.; Michel, A.

2007-01-01

Research and development methodologies for the storage of CO 2 in geological formation are in developing over the last 10 years. In this context, numerical simulators are the practical tools to understand the physical processes involved by acid gas injection and evaluate the long term stability of the storage. CO 2 storage models can be seen as a mix between two types of models: a reservoir model coupling multiphase flow in porous media with local phase equilibrium and a hydrogeochemical model coupling transport in aqueous phase with local chemical equilibrium and kinetic reaction laws. A 3D-multiphase model, COORES, was built to assess the influence of different driving forces both hydrodynamic and geomechanics as well as geochemical on the CO 2 plume behavior during injection and storage (1000 years). Different coupling strategies were used to model these phenomena: - pressure, temperature and diffusion are solved implicitly for better numerical stability; - geochemical reactions involve heterogeneous kinetically-controlled reactions between the host rock and the CO 2 -rich aqueous phase which imply an implicit coupling with fluid flow; From the assumed initial mineral composition (6 minerals), aqueous species (10 chemical elements and 37 aqueous species), the geochemical alteration of the host rocks (sand and shale) is directly linked with the CO 2 plume evolution. A performance assessment using an experimental design approach is used to quantify the different driving forces and parameter influences. In the case of CO 2 injection in a saline quartz rich aquifer used to illustrate the model capabilities, the geochemical changes of the host rock have a small influence on the CO 2 distribution at the end of storage life (here 1000 years) compared to the other hydrodynamic mechanisms: free CO 2 (gas or supercritical), or trapped (capillary and in-solution). (authors)

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

Salinization and Saline Environments

Science.gov (United States)

Vengosh, A.

2003-12-01

One of the most conspicuous phenomena of water-quality degradation, particularly in arid and semi-arid zones, is salinization of water and soil resources. Salinization is a long-term phenomenon, and during the last century many aquifers and river basins have become unsuitable for human consumption owing to high levels of salinity. Future exploitation of thousands of wells in the Middle East and in many other water-scarce regions in the world depends, to a large extent, on the degree and rate of salinization. Moreover, every year a large fraction of agricultural land is salinized and becomes unusable.Salinization is a global environmental phenomenon that affects many different aspects of our life (Williams, 2001a, b): changing the chemical composition of natural water resources (lakes, rivers, and groundwater), degrading the quality of water supply to the domestic and agriculture sectors, contribution to loss of biodiversity, taxonomic replacement by halotolerant species ( Williams, 2001a, b), loss of fertile soil, collapse of agricultural and fishery industries, changing of local climatic conditions, and creating severe health problems (e.g., the Aral Basin). The damage due to salinity in the Colorado River Basin alone, for example, ranges between 500 and 750 million per year and could exceed 1 billion per year if the salinity in the Imperial Dam increases from 700 mg L-1 to 900 mg L-1 (Bureau of Reclamation, 2003, USA). In Australia, accelerating soil salinization has become a massive environmental and economic disaster. Western Australia is "losing an area equal to one football oval an hour" due to spreading salinity ( Murphy, 1999). The annual cost for dryland salinity in Australia is estimated as AU700 million for lost land and AU$130 million for lost production ( Williams et al., 2002). In short, the salinization process has become pervasive.Salinity in water is usually defined by the chloride content (mg L-1) or total dissolved solids content (TDS, mg L-1or g

Impact of climate change on freshwater resources in a heterogeneous coastal aquifer of Bremerhaven, Germany: A three-dimensional modeling study.

Science.gov (United States)

Yang, Jie; Graf, Thomas; Ptak, Thomas

2015-01-01

Climate change is expected to induce sea level rise in the German Bight, which is part of the North Sea, Germany. Climate change may also modify river discharge of the river Weser flowing into the German Bight, which will alter both pressure and salinity distributions in the river Weser estuary. To study the long-term interaction between sea level rise, discharge variations, a storm surge and coastal aquifer flow dynamics, a 3D seawater intrusion model was designed using the fully coupled surface-subsurface numerical model HydroGeoSphere. The model simulates the coastal aquifer as an integral system considering complexities such as variable-density flow, variably saturated flow, irregular boundary conditions, irregular land surface and anthropogenic structures (e.g., dyke, drainage canals, water gates). The simulated steady-state groundwater flow of the year 2009 is calibrated using PEST. In addition, four climate change scenarios are simulated based on the calibrated model: (i) sea level rise of 1m, (ii) the salinity of the seaside boundary increases by 4 PSU (Practical Salinity Units), (iii) the salinity of the seaside boundary decreases by 12 PSU, and (iv) a storm surge with partial dyke failure. Under scenarios (i) and (iv), the salinized area expands several kilometers further inland during several years. Natural remediation can take up to 20 years. However, sudden short-term salinity changes in the river Weser estuary do not influence the salinized area in the coastal aquifer. The obtained results are useful for coastal engineering practices and drinking water resource management. Copyright © 2015 Elsevier B.V. All rights reserved.

Calcite raft geochemistry as a hydrological proxy for Holocene aquifer conditions in Hoyo Negro and Ich Balam (Sac Actun Cave System), Quintana Roo, Mexico

Science.gov (United States)

Kovacs, Shawn E.; Reinhardt, Eduard G.; Chatters, James C.; Rissolo, Dominique; Schwarcz, Henry P.; Collins, Shawn V.; Kim, Sang-Tae; Nava Blank, Alberto; Luna Erreguerena, Pilar

2017-11-01

Two cores from calcite rafts deposits located in Cenote Ich Balam and Hoyo Negro were dated and analyzed for 87Sr/86Sr, δ18O, δ13C, Sr/Ca and Cl/Ca. The geochemical records show changing aquifer salinity spanning the last ∼ 8.5 cal kyrs BP and interrelationships with Holocene climate trends (wet and dry periods). During the wet mid-Holocene, the salinity of the meteoric Water Mass (WM; at 7.8-8.3 cal kyrs BP) was relatively high at 1.5-2.7 ppt and then became less saline (1.0-1.5 ppt) during the last ∼ 7000 yrs as climate became progressively drier. High salinity of the meteoric WM during the wet mid-Holocene is attributed to increased turbulent mixing between the meteoric and underlying marine WM. Increased precipitation, in terms of amount, frequency, and intensity (e.g. hurricanes) causes higher flow of meteoric water towards the coast and mixing at the halocline, a phenomenon recorded with recent instrumental monitoring of the aquifer. Conversely, during dry periods reduced precipitation and flow in the meteoric WM would result in lower salinity. Karst properties and Holocene sea-level rise also seem to have an effect on the aquifer. When the regionally extensive network of shallow cave passages (∼ 10-12 m water depth) are flooded at ∼ 8000 cal yrs BP, there is a rapid shift in salinity. This study demonstrates that calcite raft deposits can be used as paleo-environmental recorders documenting the effects of sea level and climate change on aquifer condition.

Influence of seasonal variations in sea level on the salinity regime of a coastal groundwater-fed wetland.

Science.gov (United States)

Wood, Cameron; Harrington, Glenn A

2015-01-01

Seasonal variations in sea level are often neglected in studies of coastal aquifers; however, they may have important controls on processes such as submarine groundwater discharge, sea water intrusion, and groundwater discharge to coastal springs and wetlands. We investigated seasonal variations in salinity in a groundwater-fed coastal wetland (the RAMSAR listed Piccaninnie Ponds in South Australia) and found that salinity peaked during winter, coincident with seasonal sea level peaks. Closer examination of salinity variations revealed a relationship between changes in sea level and changes in salinity, indicating that sea level-driven movement of the fresh water-sea water interface influences the salinity of discharging groundwater in the wetland. Moreover, the seasonal control of sea level on wetland salinity seems to override the influence of seasonal recharge. A two-dimensional variable density model helped validate this conceptual model of coastal groundwater discharge by showing that fluctuations in groundwater salinity in a coastal aquifer can be driven by a seasonal coastal boundary condition in spite of seasonal recharge/discharge dynamics. Because seasonal variations in sea level and coastal wetlands are ubiquitous throughout the world, these findings have important implications for monitoring and management of coastal groundwater-dependent ecosystems. © 2014, National Ground Water Association.

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.

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.

Alluvial aquifers in the Mzingwane catchment: Their distribution, properties, current usage and potential expansion

Science.gov (United States)

Moyce, William; Mangeya, Pride; Owen, Richard; Love, David

The Mzingwane River is a sand filled channel, with extensive alluvial aquifers distributed along its banks and bed in the lower catchment. LandSat TM imagery was used to identify alluvial deposits for potential groundwater resources for irrigation development. On the false colour composite band 3, band 4 and band 5 (FCC 345) the alluvial deposits stand out as white and dense actively growing vegetation stands out as green making it possible to mark out the lateral extent of the saturated alluvial plain deposits using the riverine fringe and vegetation . The alluvial aquifers form ribbon shaped aquifers extending along the channel and reaching over 20 km in length in some localities and are enhanced at lithological boundaries. These alluvial aquifers extend laterally outside the active channel, and individual alluvial aquifers have been measured with area ranging from 45 ha to 723 ha in the channels and 75 ha to 2196 ha on the plains. The alluvial aquifers are more pronounced in the Lower Mzingwane, where the slopes are gentler and allow for more sediment accumulation. Estimated water resources potential ranges between 175,000 m 3 and 5,430,000 m 3 in the channels and between 80,000 m 3 and 6,920,000 m 3 in the plains. Such a water resource potential can support irrigation ranging from 18 ha to 543 ha for channels alluvial aquifers and 8 ha to 692 ha for plain alluvial aquifers. Currently, some of these aquifers are being used to provide water for domestic use, livestock watering and dip tanks, commercial irrigation and market gardening. The water quality of the aquifers in general is fairly good due to regular recharge and flushing out of the aquifers by annual river flows and floodwater. Water salinity was found to increase significantly in the end of the dry season, and this effect was more pronounced in water abstracted from wells on the alluvial plains. During drought years, recharge is expected to be less and if the drought is extended water levels in the

Stepped-wedge cluster-randomised controlled trial to assess the cardiovascular health effects of a managed aquifer recharge initiative to reduce drinking water salinity in southwest coastal Bangladesh: study design and rationale.

Science.gov (United States)

Naser, Abu Mohd; Unicomb, Leanne; Doza, Solaiman; Ahmed, Kazi Matin; Rahman, Mahbubur; Uddin, Mohammad Nasir; Quraishi, Shamshad B; Selim, Shahjada; Shamsudduha, Mohammad; Burgess, William; Chang, Howard H; Gribble, Matthew O; Clasen, Thomas F; Luby, Stephen P

2017-09-01

Saltwater intrusion and salinisation have contributed to drinking water scarcity in many coastal regions globally, leading to dependence on alternative sources for water supply. In southwest coastal Bangladesh, communities have few options but to drink brackish groundwater which has been associated with high blood pressure among the adult population, and pre-eclampsia and gestational hypertension among pregnant women. Managed aquifer recharge (MAR), the purposeful recharge of surface water or rainwater to aquifers to bring hydrological equilibrium, is a potential solution for salinity problem in southwest coastal Bangladesh by creating a freshwater lens within the brackish aquifer. Our study aims to evaluate whether consumption of MAR water improves human health, particularly by reducing blood pressure among communities in coastal Bangladesh. The study employs a stepped-wedge cluster-randomised controlled community trial design in 16 communities over five monthly visits. During each visit, we will collect data on participants' source of drinking and cooking water and measure the salinity level and electrical conductivity of household stored water. At each visit, we will also measure the blood pressure of participants ≥20 years of age and pregnant women and collect urine samples for urinary sodium and protein measurements. We will use generalised linear mixed models to determine the association of access to MAR water on blood pressure of the participants. The study protocol has been reviewed and approved by the Institutional Review Boards of the International Centre for Diarrheal Disease Research, Bangladesh (icddr,b). Informed written consent will be taken from all the participants. This study is funded by Wellcome Trust, UK. The study findings will be disseminated to the government partners, at research conferences and in peer-reviewed journals. NCT02746003; Pre-results. © Article author(s) (or their employer(s) unless otherwise stated in the text of the

Coupled flow and salinity transport modelling in semi-arid environments

DEFF Research Database (Denmark)

Bauer-Gottwein, Peter; Held, R.J.; Zimmermann, S.

2006-01-01

Numerical groundwater modelling is used as the base for sound aquifer system analysis and water resources assessment. In many cases, particularly in semi-arid and arid regions, groundwater flow is intricately linked to salinity transport. A case in point is the Shashe River Valley in Botswana. A ...

Isotopic, hydrochemical, and hydrogeological study of deep aquifer of Sfax: First results

International Nuclear Information System (INIS)

Maliki, M. A.; Zouari, K.; Amouri, M.

1996-01-01

The water of the chlorinated sodic with chemical facies deep aquifer of Sfax presents a difference on the level of mineralization between the northern sector with a relatively weak salin charge (average of 3,5 g/l) and the southern sector with an important mineralization (about 10g/l). The mineralization of water in linked to dissolution phenomena. Based on the first isotopic results, it seems that the present refill of the deep aquifer of Sfax is very weak (author)

Hydrogeological Investigations of the Quaternary Aquifeer in the Northern Part of El-Sharkia Governorate, Egypt

International Nuclear Information System (INIS)

El-Sayed, S.A.; Ezz El Din, M.R.; Deyab, M.E.

2011-01-01

The hydraulic characteristics of surficial soils and materials of the Quaternary aquifer in the northern part of El-Sharkia Governorate were investigated. The surficial soil zone represents an aquitard for the aquifer and mainly composed of fine textured materials having vertical hydraulic conductivity ranged from 1.4 x10 -6 cm/sec to 2.15x10 -2 cm/sec. The semi-confined Quaternary aquifer is formed of sand and gravel with occasional clay lenses. The groundwater levels ranged from 9 m (MSL) to 5 m (MSL). The major trend of groundwater flow was from south to north and northwest directions. Another minor flow trend was observed to be from southwest to northeast direction. The aquifer is essentially recharged from Ismaillia Canal. The hydraulic gradient through the flow path was 1.9 x10 -4 , averagely. The hydraulic conductivity values differ vertically and laterally indicating the heterogeneity and anisotropy of the aquifer materials. They ranged from 40.1 to 222 m/day with an average value of about 95.8 m/day. The chemical compositions of groundwater and surface water bodies (canals and drains) were investigated. The chemistry of all water bodies was characterized by a basic nature (ph =7.2-7.9) and showed different salinities values and various hydrochemical facies. The average salinities values were 318.1 mg/l for canal water, 1013.4 mg/l for groundwater and 1260 mg/l for drain water. Canal water was fresh while groundwater and drain were fresh to brackish. The reasons causing the changes in salinity and hydrochemical facies were investigated using the relationships among water dissolved constituents and trends of ionic ratios. Subsurface flow, infiltration, evaporation, ion exchange, leaching, and dissolution were the hydrochemical processes leading to the groundwater modification. The suitability of groundwater and surface water for different uses are discussed and evaluated according to the international standards.

Hydro geochemistry and isotopic approach of coastal aquifer systems of Cap Bon : The case of tablecloths and the eastern coast of El Haourai - Tunisia

International Nuclear Information System (INIS)

Ben Hammouda, Fethi

2008-01-01

As many other semi-arid regions, the Cap Bon peninsula (N.E. Tunisia) shows a parallel increase in overexploitation and mineralization of groundwater resources. In the eastern coast and El Haouaria aquifers, the groundwater quality is threatened. Surveys including level measurements, water sampling, chemical analysis (ions Na+, Cl., Ca2+, Mg2+, Br.) and sotopes (18O, 2H, 3H, 13C, 14C) were performed in 2001, 2002 and 2003. Several analysis types were conducted and results are compared with the hydrodynamic information for identifying the main processes involved in the mineralization increase. Particularly, the isotopes were permitting the understanding of the hydrogeological of the concerned aquifers and the localization of the recharge zones. Because the regional situation along the seashore, the seawater intrusion in the unconfined Plio-quaternary aquifer, resulting from the groundwater overexploitation, and obvious explanation for the rising salinity is identified but is not the only cause of the qualitative degradation: the irrigation development that induces the soil leaching and the fertilizers transfer to groundwater over the whole aquifer extent is another major reason of the mineralization increase. Piezometric and salinity maps of the Plio-quaternary aquifer were established. The continuous increase in pumping has created several depressions in the water table, up to 12 m below msl and induced a deterioration of the water quality. The temporal changes in water-table level and salinity are often similar which suggests a strong link between them. Several geochemical approaches were performed to identify the importance of the marine intrusion in the increase in mineralization. The salinity of the groundwater appears to originate from dissolution of minerals in the aquifer system

Application and evaluation of electromagnetic methods for imaging saltwater intrusion in coastal aquifers: Seaside Groundwater Basin, California

Science.gov (United States)

Nenna, Vanessa; Herckenrather, Daan; Knight, Rosemary; Odlum, Nick; McPhee, Darcy

2013-01-01

Developing effective resource management strategies to limit or prevent saltwater intrusion as a result of increasing demands on coastal groundwater resources requires reliable information about the geologic structure and hydrologic state of an aquifer system. A common strategy for acquiring such information is to drill sentinel wells near the coast to monitor changes in water salinity with time. However, installation and operation of sentinel wells is costly and provides limited spatial coverage. We studied the use of noninvasive electromagnetic (EM) geophysical methods as an alternative to installation of monitoring wells for characterizing coastal aquifers. We tested the feasibility of using EM methods at a field site in northern California to identify the potential for and/or presence of hydraulic communication between an unconfined saline aquifer and a confined freshwater aquifer. One-dimensional soundings were acquired using the time-domain electromagnetic (TDEM) and audiomagnetotelluric (AMT) methods. We compared inverted resistivity models of TDEM and AMT data obtained from several inversion algorithms. We found that multiple interpretations of inverted models can be supported by the same data set, but that there were consistencies between all data sets and inversion algorithms. Results from all collected data sets suggested that EM methods are capable of reliably identifying a saltwater-saturated zone in the unconfined aquifer. Geophysical data indicated that the impermeable clay between aquifers may be more continuous than is supported by current models.

The long-term impacts of anthropogenic and natural processes on groundwater deterioration in a multilayered aquifer.

Science.gov (United States)

Sheikhy Narany, Tahoora; Sefie, Anuar; Aris, Ahmad Zaharin

2018-07-15

In many regions around the world, there are issues associated with groundwater resources due to human and natural factors. However, the relation between these factors is difficult to determine due to the large number of parameters and complex processes required. In order to understand the relation between land use allocations, the intrinsic factors of the aquifer, climate change data and groundwater chemistry in the multilayered aquifer system in Malaysia's Northern Kelantan Basin, twenty-two years hydrogeochemical data set was used in this research. The groundwater salinisation in the intermediate aquifer, which mainly extends along the coastal line, was revealed through the hydrogeochemical investigation. Even so, there had been no significant trend detected on groundwater salinity from 1989 to 2011. In contrast to salinity, as seen from the nitrate contaminations there had been significantly increasing trends in the shallow aquifer, particularly in the central part of the study area. Additionally, a strong association between high nitrate values and the areas covered with palm oil cultivations and mixed agricultural have been detected by a multiple correspondence analysis (MCA), which implies that the increasing nitrate concentrations are associated with nitrate loading from the application of N-fertilisers. From the process of groundwater salinisation in the intermediate aquifer, could be seen that it has a strong correlation the aquifer lithology, specifically marine sediments which are influenced by the ancient seawater trapped within the sediments. Copyright © 2018 Elsevier B.V. All rights reserved.

Formation of magmatic brine lenses via focussed fluid-flow beneath volcanoes

Science.gov (United States)

Afanasyev, Andrey; Blundy, Jon; Melnik, Oleg; Sparks, Steve

2018-03-01

Many active or dormant volcanoes show regions of high electrical conductivity at depths of a few kilometres beneath the edifice. We explore the possibility that these regions represent lenses of high-salinity brine separated from a single-phase magmatic fluid containing H2O and NaCl. Since chloride-bearing fluids are highly conductive and have an exceptional capacity to transport metals, these regions can be an indication of an active hydrothermal ore-formation beneath volcanoes. To investigate this possibility we have performed hydrodynamic simulations of magma degassing into permeable rock. In our models the magma source is located at 7 km depth and the fluid salinity approximates that expected for fluids released from typical arc magmas. Our model differs from previous models of a similar process because it is (a) axisymmetric and (b) includes a static high-permeability pathway that links the magma source to the surface. This pathway simulates the presence of a volcanic conduit and/or plexus of feeder dykes that are typical of most volcanic systems. The presence of the conduit leads to a number of important hydrodynamic consequences, not observed in previous models. Importantly, we show that an annular brine lens capped by crystallised halite is likely to form above an actively degassing sub-volcanic magma body and can persist for more than 250 kyr after degassing ceases. Parametric analysis shows that brine lenses are more prevalent when the fluid is released at temperatures above the wet granite solidus, when magmatic fluid salinity is high, and when the high-permeability pathway is narrow. The calculated depth, form and electrical conductivity of our modelled system shares many features with published magnetotelluric images of volcano subsurfaces. The formation and persistence of sub-volcanic brine lenses has implications for geothermal systems and hydrothermal ore formation, although these features are not explored in the presented model.

Effects of a Reservoir Water on the GW Quality in a Coastal Aquifer of Semi-arid Region, North-east of Tunisia

Science.gov (United States)

Uchida, C.; Kawachi, A.; Tsujimura, M.; Tarhouni, J.

2015-12-01

This study investigated effects of a reservoir water in a salinized shallow aquifer based on spatial distribution of geochemical properties in groundwater (GW). In many coastal shallow aquifers of arid and semi-arid regions, groundwater table (GWT) depression and salinization have occurred due to GW overexploitation. In Korba aquifer, north-east of Tunisia, after a dam reservoir has been constructed in order to assure a water resource for irrigation, improvement of GW level and quality have been observed in the downstream area of the dam (area-A), while the GW in the other area (area-B) still has high salinity. This study, therefore, aimed to investigate the effects of the reservoir water on the GW quality. In June 2013, water quality survey and sampling were carried out at 60 wells (GW), a dam reservoir, river and the sea. Major ions, boron, bromide, and oxygen-18 and deuterium in collected samples were analyzed. From the results, in the area-B, the GWT was lower than the sea level and the high salinity were observed. The Br- concentration of the GW was correlated with the Cl- concentration, and the values of B/Cl- and Br-/Cl- of the GW were similar to the seawater. Since the GWT depression allowed the seawater to intrude into the aquifer, the GW salinization occurred in this area. On the other hand, in the area-A, GWT was higher than the seawater level, and the Na+ and Cl- concentrations were lower than the area-B. Especially, in the irrigated areas by using the reservoir water, the isotopic values, B/Cl- and Br-/Cl- of the GW were relatively higher than the others. The reservoir water has high isotopic values due to evaporation effect, and the B/Cl- and Br-/Cl- values become higher due to organic matters in sediment of the reservoir or soil in the filtration process. Thus, in addition to the direct infiltration from the reservoir into the aquifer, irrigation using a reservoir water probably has a positive impact on the GW quality in this area.

Glacial recharge, salinisation and anthropogenic contamination in the coastal aquifers of Recife (Brazil)

Energy Technology Data Exchange (ETDEWEB)

Chatton, E., E-mail: eliot.chatton@gmail.com [Géosciences Rennes, Université Rennes 1-CNRS, UMR 6118, adress: 263 av du général Leclerc, Campus de Beaulieu, bat 15, 35042 Rennes Cedex (France); Aquilina, L., E-mail: luc.aquilina@univ-rennes1.fr [Géosciences Rennes, Université Rennes 1-CNRS, UMR 6118, adress: 263 av du général Leclerc, Campus de Beaulieu, bat 15, 35042 Rennes Cedex (France); Pételet-Giraud, E., E-mail: e.petelet@brgm.fr [Bureau de Recherches Géologiques et Minières (BRGM), adress: 3 avenue Claude-Guillemin, BP 36009, 45060 Orléans Cedex 2 (France); Cary, L., E-mail: l.cary@brgm.fr [Bureau de Recherches Géologiques et Minières (BRGM), adress: 3 avenue Claude-Guillemin, BP 36009, 45060 Orléans Cedex 2 (France); Bertrand, G., E-mail: guillaume353@gmail.com [Instituto de Geociências, CEPAS (Groundwater Research Center), University of São Paulo, adress: Rua do lago 562, 05508-080 Sao Paulo (Brazil); Labasque, T., E-mail: thierry.labasque@univ-rennes1.fr [Géosciences Rennes, Université Rennes 1-CNRS, UMR 6118, adress: 263 av du général Leclerc, Campus de Beaulieu, bat 15, 35042 Rennes Cedex (France); and others

2016-11-01

Implying large residence times and complex water origins deep coastal aquifers are of particular interest as they are remarkable markers of climate, water use and land use changes. Over the last decades, the Metropolitan Region of Recife (Brazil) went through extensive environmental changes increasing the pressure on water resources and giving rise to numerous environmental consequences on the coastal groundwater systems. We analysed the groundwater of the deep aquifers Cabo and Beberibe that are increasingly exploited. The processes potentially affecting groundwater residence times and flow paths have been studied using a multi-tracer approach (CFCs, SF6, noble gases, 14C, 2H and 18O). The main findings of these investigations show that: (1) Groundwaters of the Cabo and Beberibe aquifers have long residence times and were recharged about 20,000 years ago. (2) Within these old groundwaters we can find palaeo-climate evidences from the last glacial period at the tropics with lower temperatures and dryer conditions than the present climate. (3) Recently, the natural slow dynamic of these groundwater systems was significantly affected by mixing processes with contaminated modern groundwater coming from the shallow unconfined Boa Viagem aquifer. (4) The large exploitation of these aquifers leads to a modification of the flow directions and causes the intrusion through palaeo-channels of saline water probably coming from the Capibaribe River and from the last transgression episodes. These observations indicate that the current exploitation of the Cabo and Beberibe aquifers is unsustainable regarding the long renewal times of these groundwater systems as well as their ongoing contamination and salinisation. The groundwater cycle being much slower than the human development rhythm, it is essential to integrate the magnitude and rapidity of anthropogenic impacts on this extremely slow cycle to the water management concepts. - Highlights: • Study of anthropogenic impacts

Glacial recharge, salinisation and anthropogenic contamination in the coastal aquifers of Recife (Brazil)

International Nuclear Information System (INIS)

Chatton, E.; Aquilina, L.; Pételet-Giraud, E.; Cary, L.; Bertrand, G.; Labasque, T.

2016-01-01

Implying large residence times and complex water origins deep coastal aquifers are of particular interest as they are remarkable markers of climate, water use and land use changes. Over the last decades, the Metropolitan Region of Recife (Brazil) went through extensive environmental changes increasing the pressure on water resources and giving rise to numerous environmental consequences on the coastal groundwater systems. We analysed the groundwater of the deep aquifers Cabo and Beberibe that are increasingly exploited. The processes potentially affecting groundwater residence times and flow paths have been studied using a multi-tracer approach (CFCs, SF6, noble gases, 14C, 2H and 18O). The main findings of these investigations show that: (1) Groundwaters of the Cabo and Beberibe aquifers have long residence times and were recharged about 20,000 years ago. (2) Within these old groundwaters we can find palaeo-climate evidences from the last glacial period at the tropics with lower temperatures and dryer conditions than the present climate. (3) Recently, the natural slow dynamic of these groundwater systems was significantly affected by mixing processes with contaminated modern groundwater coming from the shallow unconfined Boa Viagem aquifer. (4) The large exploitation of these aquifers leads to a modification of the flow directions and causes the intrusion through palaeo-channels of saline water probably coming from the Capibaribe River and from the last transgression episodes. These observations indicate that the current exploitation of the Cabo and Beberibe aquifers is unsustainable regarding the long renewal times of these groundwater systems as well as their ongoing contamination and salinisation. The groundwater cycle being much slower than the human development rhythm, it is essential to integrate the magnitude and rapidity of anthropogenic impacts on this extremely slow cycle to the water management concepts. - Highlights: • Study of anthropogenic impacts

Impact of saline aquifer water on surface and shallow pit corrosion of martensitic stainless steels during exposure to CO2 environment (CCS)

Science.gov (United States)

Pfennig, Anja; Kranzmann, Axel

2018-05-01

Pipe steels suitable for carbon capture and storage technology (CCS) require resistance against the corrosive environment of a potential CCS-site, e.g. heat, pressure, salinity of the aquifer, CO2-partial pressure. Samples of different mild and high alloyed stainless injection-pipe steels partially heat treated: 42CrMo4, X20Cr13, X46Cr13, X35CrMo4 as well as X5CrNiCuNb16-4 were kept at T=60 °C and ambient pressure as well as p=100 bar for 700 h - 8000 h in a CO2-saturated synthetic aquifer environment similar to possible geological on-shore CCS-sites in the northern German Basin. Main corrosion products are FeCO3 and FeOOH. Corrosion rates obtained at 100 bar are generally much lower than those measured at ambient pressure. Highest surface corrosion rates are 0.8 mm/year for 42CrMo4 and lowest 0.01 mm/year for X5CrNiCuNb16-4 in the vapour phase at ambient pressure. At 100 bar the highest corrosion rates are 0.01 mm/year for 42CrMo4, X20Cr13 (liquid phase), X46Cr13 and less than 0.01 mm/year for X35CrMo4 and X5CrNiCuNb16-4 after 8000 h of exposure with no regard to atmosphere. Martensitic microstructure offers good corrosion resistance.

Synergy of climate change and local pressures on saltwater intrusion in heterogeneous coastal aquifers

Science.gov (United States)

Abou Najm, M.; Safi, A.; El-Fadel, M.; Doummar, J.; Alameddine, I.

2016-12-01

The relative importance of climate change induced sea level rise on the salinization of a highly urbanized karstified coastal aquifers were compared with non-sustainable pumping. A 3D variable-density groundwater flow and solute transport model was used to predict the displacement of the saltwater-freshwater interface in a pilot aquifer located along the Eastern Mediterranean. The results showed that the influence of sea level rise was marginal when compared with the encroachment of salinity associated with anthropogenic abstraction. Model predictions of salinity mass and volumetric displacement of the interface corresponding to a long-term monthly transient model showed that the saltwater intrusion dynamic is highly sensitive to change in the abstraction rates which were estimated based on combinations of water consumption rates and population growth rates. Salinity encroachment, however, appeared to be more sensitive to water consumption rates in comparison to population growth rates, where a 50% increase in the rate of former led to four times more intrusion as compared to an equivalent increase in population growth rate over 20 years. Coupling both increase in population growth and increased consumption rates had a synergistic effect that aggravated the intrusion beyond the sum of the individual impacts. Adaptation strategies targeting a decrease in groundwater exploitation proved to be effective in retarding the intrusion.

Water hydrochemical of the Punta Espinillo fissured aquifer, Montevideo-Uruguay

International Nuclear Information System (INIS)

Montano, J.; Peel, E.; Sienra, M.; Gianotti, V.; Lacues, X. . E mail: montanox@movinet.com.uy

2004-01-01

In the westernmost part of the Department of Montevideo an intensive agronomic activity is developed based on irrigation systems. There, the majority of the vegetables and fruits consumed in Montevideo city are produced. The studied area consists in approximately 1500 ha. divided into orchards of 5 ha or less. Former studies show that salinization risk is due to the proximity of de La Plata river and / or the draw - downs in static levels because of over exploitation. The aquifer type is fractured and shows flows from 2 m3/h to 20 m3/h. The aim of this work is to perform a preliminary hydrochemical characterization of the Punta Espinillo fractured aquifer system and to determine human use and irrigation aptitudes. The results show that the groundwater is sodi c bi carbonated and it varies from hard to very hard. Moreover, from the correlation studies between hydrochemical parameters it is observed that Cl- and SO42- ions are responsible for the high salinity. It is also observed that exist important restrictions for human and irrigation use [es

Water quality considerations on the rise as the use of managed aquifer recharge systems widens

OpenAIRE

Hartog, Niels; Stuyfzand, Pieter J.

2017-01-01

Managed Aquifer Recharge (MAR) is a promising method of increasing water availability in water stressed areas by subsurface infiltration and storage, to overcome periods of drought, and to stabilize or even reverse salinization of coastal aquifers. Moreover, MAR could be a key technique in making alternative water resources available, such as reuse of communal effluents for agriculture, industry and even indirect potable reuse. As exemplified by the papers in this Special Issue, consideration...

Isotopic evidence for induced river recharge to the Dupi Tila aquifer in the Dhaka urban area, Bangladesh

International Nuclear Information System (INIS)

Darling, W.G.; Burgess, W.G.; Hasan, M.K.

2002-01-01

The population of the greater Dhaka metropolitan area is over 8 million and growing at a rate of six percent per year. Much of the water supply for the area is obtained from the underlying Dupi Tila sand aquifer. Intensive exploitation of the aquifer has led to a progressive decline in water levels beneath the parts of the city. The resulting cone of depression is thought likely to be causing the infiltration of surface water, largely from the polluted Buriganga waterway. The use of oxygen and hydrogen stable isotopes in unravelling the subsurface hydrology of the Dhaka area is hindered by the lack of data regarding 'baseline' conditions. Nevertheless it is clear from the evidence obtained from tubewells across the city that there is leakage from the Buriganga river extending several kilometres beneath parts of the urban area, possibly as far as the centre of the city. Carbon stable isotopes and major ion chemistry confirm this general picture; though appear to indicate that polluted river water has not penetrated quite so far towards the city centre. The Dupi Tila is regarded as a multi-layer aquifer on the basis of its hydrogeology and water quality variations with depth. Since there is little stable isotopic evidence for stratification, future investigations should include sensitive recent age indicators to investigate this, and the rates of groundwater movement in general. (author)

Localized sulfate-reducing zones in a coastal plain aquifer

Science.gov (United States)

Brown, C.J.; Coates, J.D.; Schoonen, M.A.A.

1999-01-01

High concentrations of dissolved iron in ground water of coastal plain or alluvial aquifers contribute to the biofouling of public supply wells for which treatment and remediation is costly. Many of these aquifers, however, contain zones in which microbial sulfate reduction and the associated precipitation of iron-sulfide minerals decreases iron mobility. The principal water-bearing aquifer (Magothy Aquifer of Cretaceous age) in Suffolk County, New York, contains localized sulfate-reducing zones in and near lignite deposits, which generally are associated with clay lenses. Microbial analyses of core samples amended with [14C]-acetate indicate that microbial sulfate reduction is the predominant terminal-electron-accepting process (TEAP) in poorly permeable, lignite-rich sediments at shallow depths and near the ground water divide. The sulfate-reducing zones are characterized by abundant lignite and iron-sulfide minerals, low concentrations of Fe(III) oxyhydroxides, and by proximity to clay lenses that contain pore water with relatively high concentrations of sulfate and dissolved organic carbon. The low permeability of these zones and, hence, the long residence time of ground water within them, permit the preservation and (or) allow the formation of iron-sulfide minerals, including pyrite and marcasite. Both sulfate-reducing bacteria (SRB) and iron-reducing bacteria (IRB) are present beneath and beyond the shallow sulfate-reducing zones. A unique Fe(III)-reducing organism, MD-612, was found in core sediments from a depth of 187 m near the southern shore of Long Island. The distribution of poorly permeable, lignite-rich, sulfate-reducing zones with decreased iron concentration is varied within the principal aquifer and accounts for the observed distribution of dissolved sulfate, iron, and iron sulfides in the aquifer. Locating such zones for the placement of production wells would be difficult, however, because these zones are of limited aerial extent.

Groundwater-level and storage-volume changes in the Equus Beds aquifer near Wichita, Kansas, predevelopment through January 2015

Science.gov (United States)

Whisnant, Joshua A.; Hansen, Cristi V.; Eslick, Patrick J.

2015-10-01

Development of the Wichita well field began in the 1940s in the Equus Beds aquifer to provide the city of Wichita, Kansas, a new water-supply source. After development of the Wichita well field began, groundwater levels began to decline. Extensive development of irrigation wells that began in the 1970s also contributed to substantial groundwater-level declines. Groundwater-level declines likely enhance movement of brine from past oil and gas production near Burrton, Kansas, and natural saline water from the Arkansas River into the Wichita well field. Groundwater levels reached a historical minimum in 1993 because of drought conditions, irrigation, and the city of Wichita’s withdrawals from the aquifer. In 1993, the city of Wichita adopted the Integrated Local Water Supply Program to ensure that Wichita’s water needs would be met through the year 2050 and beyond as part of its efforts to manage the part of the Equus Beds aquifer Wichita uses. A key component of the Integrated Local Water Supply Program was the Equus Beds Aquifer Storage and Recovery project. The Aquifer Storage and Recovery project’s goal is to store and eventually recover groundwater and help protect the Equus Beds aquifer from oil-field brine water near Burrton, Kansas, and saline water from the Arkansas River. Since 1940, the U.S. Geological Survey has monitored groundwater levels and storage-volume changes in the Equus Beds aquifer to provide data to the city of Wichita in order to better manage its water supply.

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

Radionuclides, Heavy Metals and Fluoride Contamination in Al Bahira Aquifer, Youssoufia Area, Morocco

Energy Technology Data Exchange (ETDEWEB)

Agma, T. T; Bouchaou, L.; Ettayfi, N.; Lgourna, Z.; Boutaleb, S. [Ibn Zohr University, Applied Geology and Geo-Environment Laboratory, Cite Dakhla, Agadir 80060 (Morocco); Warner, N.; Vengosh, A. [Duke University, Division of Earth and Ocean Sciences, Durham, NC 27708 (United States)

2013-07-15

This study investigates the geochemistry and quantity of trace metals and naturally occurring radionuclides (Ra, U) in the shallow groundwater in the western part of the Al Bahira aquifer (Phosphate Plateau) located in west central Morocco. Groundwater is characterized by a wide salinity range (TDS of 540 to 9286 mg/l) and shows systematic linear relationships between the major dissolved constituents. These relationships suggest that the mixing of a single saline source and fresh water controls the quality of groundwater. Fluoride, uranium, selenium, and arsenic concentrations are also correlated with salinity. The activity concentrations of Radium-226 exceed the US-EPA drinking water standard. Radium-226 activity in the groundwater is not directly related to salinity and might be affected by other factors such as water temperature. The low ratios of the short lived Ra-224 to Ra-223 ({approx}2) indicate that Ra was derived from a uranium rich source with a low Th/U ratio in the rock source, which is consistent with the Urich lithology of the aquifer (e.g., phosphate rocks). The high levels of contaminants found in the shallow groundwater samples have important health implications for the local population, as shallow groundwater is used for drinking water in the rural communities northwest of Marrakech and these contaminants pose potential serious health problems (e.g., dental fluorosis, kidney disease, and bone cancer). (author)

Salinization mechanisms in semi-arid regions

International Nuclear Information System (INIS)

Santiago, M.M.F.

1984-01-01

During a period of three years the basins of the Pereira de Miranda and Caxitore dams, located in the crystalline rock area of Ceara, Brazil, were studied in order to determine the mechanisms of salinization of their waters. Isotope methods ( 18 O/ 16 O) and hidrochemistry (determination of the of the maior ions) were applied to surface, underground and rain water in this study. An isotope model was designed and applied to the determination of evaporation and percolation of dams in semi-arid zones during the dry season. The results are compared to those from a conventional chemical model. As causes of salinization of the water in the dams, the contributions of the rain itself and the lixiviation of the soil are quantified. An interaction between the dams and the underground water is imperceptible. The salinization of the underground water is attributed to recharge of the aquifer with rain water from the surface runoff followed by evaporation of the water rising, due to capilarity, in a one-directional flow to the surface. (Author) [pt

Geochemistry and environmental isotope of groundwater from the upper Cretaceous aquifer of Orontes basin (Syria)

International Nuclear Information System (INIS)

Al-Charideh, A.

2010-03-01

Chemical and environmental isotopes have been used for studying the Upper Cretaceous aquifer systems in the Middle Orontes basin. The results indicate that the salinity of groundwater (0.2 to 2 g/l) reveals the dissolution of evaporate rocks is the main factor of high salinity especially in the Homes depression. The degree of salinity and its spaces distribution are basically related to the pattern of groundwater movement in the Upper cretaceous aquifer. The stable isotopes composition of groundwater in the Homes depression are more depleted by -2.5% and -17.0% for δ 18 O and δ 2 H respectively, than the groundwater from Hama elevation, suggested different origin and recharge time between this two groundwater groups. Estimates of their mean subsurface residence times have been constrained on the basis of 14 C D IC. The corrected ages of groundwater are recent and less to 10 thousand years in Hama uplift. However, the corrected age of groundwater in the Homs depression range between 10 to 25 thousand years indicate late Pleistocene recharge period. (author)

Integral Analysis of Field Work and Laboratory Electrical Resistivity Imaging for Saline Water Intrusion Prediction in Groundwater

Science.gov (United States)

Zawawi, M. H.; Zahar, M. F.; Hashim, M. M. M.; Hazreek, Z. A. M.; Zahari, N. M.; Kamaruddin, M. A.

2018-04-01

Saline water intrusion is a serious threat to the groundwater as many part of the world utilize groundwater as their main source of fresh water supply. The usage of high salinity level of water as drinking water can lead to a very serious health hazard towards human. Saline water intrusion is a process by which induced flow of seawater into freshwater aquifer along the coastal area. It might happen due to human action and/or by natural event. The climate change and rise up of sea level may speed up the saline water intrusion process. The conventional method for distinguishing and checking saltwater interference to groundwater along the coast aquifers is to gather and test the groundwater from series of observation wells (borehole) with an end goal to give the important information about the hydrochemistry data to conclude whether the water in the well are safe to consume or not. An integrated approach of field and laboratory electrical resistivity investigation is proposed for indicating the contact region between saline and fresh groundwater. It was found that correlation for both soilbox produced almost identical curvilinear trends for 2% increment of seawater tested using sand sample. This project contributes towards predicting the saline water intrusion to the groundwater by non-destructive test that can replaced the conventional method of groundwater monitoring using series of boreholes in the coastal area

Hydrogeology of the Ramapo River-Woodbury Creek valley-fill aquifer system and adjacent areas in eastern Orange County, New York

Science.gov (United States)

Heisig, Paul M.

2015-01-01

The hydrogeology of the valley-fill aquifer system and surrounding watershed areas was investigated within a 23-mile long, fault-controlled valley in eastern Orange County, New York. Glacial deposits form a divide within the valley that is drained to the north by Woodbury Creek and is drained to the south by the Ramapo River. Surficial geology, extent and saturated thickness of sand and gravel aquifers, extent of confining units, bedrock-surface elevation beneath valleys, major lineaments, and the locations of wells for which records are available were delineated on an interactive map.

Effect of Groundwater Pumping on Seawater Intrusion in Coastal Aquifers

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M.M. Sherif

2002-06-01

Full Text Available Many aquifers around the globe are located in coastal areas and are thus subjected to the seawater intrusion phenomenon. The growth of population in coastal areas and the conjugate increase in human, agricultural, and industrial activities have imposed an increasing demand for freshwater. This increase in water demand is often covered by extensive pumping of fresh groundwater, causing subsequent lowering of the water table (or piezometric head and upsetting the dynamic balance between freshwater and saline water bodies. The classical result of such a development is seawater intrusion. This paper presents a review for the seawater intrusion phenomenon in coastal aquifers. The effect of pumping activities on the seawater intrusion in the Nile Delta aquifer of Egypt is investigated. It was concluded that any additional pumping should be located in the middle Delta and avoided in the eastern and western sides of the Delta.

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

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.

Microbiological monitoring of carbon dioxide storage in a subsurface saline aquifer in Ketzin/Germany within the scope of CO2SINK

Science.gov (United States)

Wandrey, M.; Morozova, D.; Zemke, K.; Lerm, S.; Scherf, A.-K.; Vieth, A.; Würdemann, H.; Co2SINK Group

2009-04-01

Within the scope of the EU project CO2SINK (www.co2sink.org) a research facility in Ketzin (Germany, west of Berlin) is operated to store CO2 in a saline subsurface aquifer (Würdemann et al., EGU General Assembly 2009). In order to examine the influence of CO2 storage on the environment a comprehensive monitoring program is applied at this site including molecular and microbiological investigations. With the injection of CO2 into the geological formation chemical and physical reservoir characteristics are changed. This may influence the composition and activities of the deep biosphere at the storage horizon. Mineral precipitation, dissolution and corrosion of reservoir casing may be consequences, influencing permeability and long-term stability of the reservoir. The objective of the microbial monitoring program is the characterisation of the microbial community (biocenosis) in fluid samples, as well as in samples from reservoir and cap rock before and during CO2storage using molecular biological methods. 16S rRNA taxonomic studies, Fluorescence in situ hybridisation (FISH), and RealTime PCR are used to examine the composition of the biocenosis. First results of fluid sampling revealed that the microbial community of the saline aquifer is dominated by haloalkaliphilic fermentative bacteria and extremophilic organisms, coinciding with reduced conditions, high salinity and pressure. RealTime RT-PCR of selected genes and the creation and analysis of cDNA libraries will allow the prediction of microbial metabolic activities. In addition, the analysis of organic and inorganic components of the samples will add to the knowledge of possible metabolic shifts during CO2 storage. In order to simulate the storage conditions in situ, long term laboratory experiments in high pressure incubators have been set up using original rock cores from Ketzin. Since DNA and RNA analysis techniques are very sensitive, contamination entries from the adjacent environment have to be excluded

Using geochemical investigations for determining the interaction between groundwater and saline water in arid areas: case of the Wadi Ouazzi basin (Morocco

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R. El Moukhayar

2015-04-01

Full Text Available The characteristics of the Essaouira basin water resources are a semi-arid climate, which is severely impacted by the climate (quantity and quality. Considering the importance of the Essaouira aquifer in the groundwater supply of the region, a study was conducted in order to understand groundwater evolution in this aquifer. The Essaouira aquifer is a coastal aquifer located on the Atlantic coastline of southern Morocco, corresponding to a sedimentary basin with an area of nearly 200 km2. The control of the fluid exchange and the influence of mixing zones between the groundwater and saline water was investigated by sampling from 20 wells, drillings and sources belonging to the Plio-Quaternary and Turonian aquifers. It is hypothesized that groundwater major ions chemistry can be employed to determine the interaction between the groundwater and saline water (coastal aquifers. Groundwater samples examined for electric conductivity and temperature showed that waters belonging to the Plio-Quaternary and Turonian aquifers present very variable electric conductivities, from 900 μs/cm to 3880 μs/cm. Despite this variability, they are from the same family and are characterized by sodium-chloride facies. However, a good correlation exists between the electrical conductivity and chloride and sodium contents. The lower electrical conductivities are situated in the North quarter immediately to the south of the Wadi Ouazzi.

Fresh Water Generation from Aquifer-Pressured Carbon Storage: Annual Report FY09

Energy Technology Data Exchange (ETDEWEB)

Wolery, T; Aines, R; Hao, Y; Bourcier, W; Wolfe, T; Haussman, C

2009-11-25

This project is establishing the potential for using brine pressurized by Carbon Capture and Storage (CCS) operations in saline formations as the feedstock for desalination and water treatment technologies including reverse osmosis (RO) and nanofiltration (NF). The aquifer pressure resulting from the energy required to inject the carbon dioxide provides all or part of the inlet pressure for the desalination system. Residual brine is reinjected into the formation at net volume reduction, such that the volume of fresh water extracted balances the volume of CO{sub 2} injected into the formation. This process provides additional CO{sub 2} storage capacity in the aquifer, reduces operational risks (cap-rock fracturing, contamination of neighboring fresh water aquifers, and seismicity) by relieving overpressure in the formation, and provides a source of low-cost fresh water to offset costs or operational water needs. This multi-faceted project combines elements of geochemistry, reservoir engineering, and water treatment engineering. The range of saline formation waters is being identified and analyzed. Computer modeling and laboratory-scale experimentation are being used to examine mineral scaling and osmotic pressure limitations. Computer modeling is being used to evaluate processes in the storage aquifer, including the evolution of the pressure field. Water treatment costs are being evaluated by comparing the necessary process facilities to those in common use for seawater RO. There are presently limited brine composition data available for actual CCS sites by the site operators including in the U.S. the seven regional Carbon Sequestration Partnerships (CSPs). To work around this, we are building a 'catalog' of compositions representative of 'produced' waters (waters produced in the course of seeking or producing oil and gas), to which we are adding data from actual CCS sites as they become available. Produced waters comprise the most common

Origins and delineation of saltwater intrusion in the Biscayne aquifer and changes in the distribution of saltwater in Miami-Dade County, Florida

Science.gov (United States)

Prinos, Scott T.; Wacker, Michael A.; Cunningham, Kevin J.; Fitterman, David V.

2014-01-01

Intrusion of saltwater into parts of the shallow karst Biscayne aquifer is a major concern for the 2.5 million residents of Miami-Dade County that rely on this aquifer as their primary drinking water supply. Saltwater intrusion of this aquifer began when the Everglades were drained to provide dry land for urban development and agriculture. The reduction in water levels caused by this drainage, combined with periodic droughts, allowed saltwater to flow inland along the base of the aquifer and to seep directly into the aquifer from the canals. The approximate inland extent of saltwater was last mapped in 1995. An examination of the inland extent of saltwater and the sources of saltwater in the aquifer was completed during 2008–2011 by using (1) all available salinity information, (2) time-series electromagnetic induction log datasets from 35 wells, (3) time-domain electromagnetic soundings collected at 79 locations, (4) a helicopter electromagnetic survey done during 2001 that was processed, calibrated, and published during the study, (5) cores and geophysical logs collected from 8 sites for stratigraphic analysis, (6) 8 new water-quality monitoring wells, and (7) analyses of 69 geochemical samples. The results of the study indicate that as of 2011 approximately 1,200 square kilometers (km2) of the mainland part of the Biscayne aquifer were intruded by saltwater. The saltwater front was mapped farther inland than it was in 1995 in eight areas totaling about 24.1 km2. In many of these areas, analyses indicated that saltwater had encroached along the base of the aquifer. The saltwater front was mapped closer to the coast than it was in 1995 in four areas totaling approximately 6.2 km2. The changes in the mapped extent of saltwater resulted from improved spatial information, actual movement of the saltwater front, or a combination of both. Salinity monitoring in some of the canals in Miami-Dade County between 1988 and 2010 indicated influxes of saltwater, with maximum

Paleohydrology of the southern Great Basin, with special reference to water table fluctuations beneath the Nevada Test Site during the late(?) Pleistocene

Science.gov (United States)

Winograd, Isaac Judah; Doty, Gene C.

1980-01-01

Knowledge of the magnitude of water-table rise during Pleistocene pluvial climates, and of the resultant shortening of groundwater flow path and reduction in unsaturated zone thickness, is mandatory for a technical evaluation of the Nevada Test Site (NTS) or other arid zone sites as repositories for high-level or transuranic radioactive wastes. The distribution of calcitic veins filling fractures in alluvium, and of tufa deposits between the Ash Meadows spring discharge area and the Nevada Test Site indicates that discharge from the regional Paleozoic carbonate aquifer during the Late( ) Pleistocene pluvial periods may have occurred at an altitude about 50 meters higher than at present and 14 kilometers northeast of Ash Meadows. Use of the underflow equation (relating discharge to transmissivity, aquifer width, and hydraulic gradient), and various assumptions regarding pluvial recharge, transmissivity, and altitude of groundwater base level, suggest possible rises in potentiometric level in the carbonate aquifer of about -90 meters beneath central Frenchman Flat. During Wisconsin time the rise probably did not exceed 30 meters. Water-level rises beneath Frenchman Flat during future pluvials are unlikely to exceed 30 meters and might even be 10 meters lower than modern levels. Neither the cited rise in potentiometric level in the regional carbonate aquifer, nor the shortened flow path during the Late( ) Pleistocene preclude utilization of the NTS as a repository for high-level or transuranic-element radioactive wastes provided other requisite conditions are met as this site. Deep water tables, attendant thick (up to several hundred meter) unsaturated zones, and long groundwater flow paths characterized the region during the Wisconsin Stage and probably throughout the Pleistocene Epoch and are likely to so characterize it during future glacial periods. (USGS)

The Dammam aquifer in Bahrain - Hydrochemical characterization and alternatives for management of groundwater quality

Science.gov (United States)

Zubari, Waleed K.

Over-ion of the Dammam aquifer, the principal aquifer in Bahrain, by the agricultural and domestic sectors, has led to its salinization by adjacent brackish and saline water bodies. A hydrochemical study identified the locations of the sources of aquifer salinization and delineated their areas of influence. The investigation indicates that the aquifer water quality is significantly modified as groundwater flows from the northwestern parts of Bahrain, where the aquifer receives its water by lateral underflow from eastern Saudi Arabia, to the southern and southeastern parts. Four types of salinization of the aquifer are identified: brackish-water up-flow from the underlying brackish-water zones in north-central, western, and eastern regions; seawater intrusion in the eastern region; intrusion of sabkha water in the southwestern region; and irrigation return flow in a local area in the western region. Four alternatives for the management of groundwater quality that are available to the water authorities in Bahrain are discussed and their priority areas are proposed, based on the type and extent of each salinization source, in addition to groundwater use in that area. The effectiveness of the proposed management options in controlling the degradation of water quality in the Dammam aquifer should be evaluated using simulation modeling. Résumé La surexploitation de l'aquifère de Damman, principal aquifère de Bahreïn, du fait des besoins agricoles et domestiques, a conduit à sa salinisation à partir d'eaux voisines saumâtres et salées. Une étude hydrochimique a identifié les origines de la salinisation de l'aquifère et a délimité leurs zones d'influence. Les recherches montrent que la qualité de l'eau souterraine est modifiée de façon significative pour les écoulements souterrains dirigés vers les secteurs sud et sud-est et provenant de la région nord-ouest de Bahreïn, là où l'aquifère est alimenté latéralement à partir de l'Arabie Saoudite

Karst Aquifer Recharge: A Case History of over Simplification from the Uley South Basin, South Australia

Directory of Open Access Journals (Sweden)

Nara Somaratne

2015-02-01

Full Text Available The article “Karst aquifer recharge: Comments on ‘Characteristics of Point Recharge in Karst Aquifers’, by Adrian D. Werner, 2014, Water 6, doi:10.3390/w6123727” provides misrepresentation in some parts of Somaratne [1]. The description of Uley South Quaternary Limestone (QL as unconsolidated or poorly consolidated aeolianite sediments with the presence of well-mixed groundwater in Uley South [2] appears unsubstantiated. Examination of 98 lithological descriptions with corresponding drillers’ logs show only two wells containing bands of unconsolidated sediments. In Uley South basin, about 70% of salinity profiles obtained by electrical conductivity (EC logging from monitoring wells show stratification. The central and north central areas of the basin receive leakage from the Tertiary Sand (TS aquifer thereby influencing QL groundwater characteristics, such as chemistry, age and isotope composition. The presence of conduit pathways is evident in salinity profiles taken away from TS water affected areas. Pumping tests derived aquifer parameters show strong heterogeneity, a typical characteristic of karst aquifers. Uley South QL aquifer recharge is derived from three sources; diffuse recharge, point recharge from sinkholes and continuous leakage of TS water. This limits application of recharge estimation methods, such as the conventional chloride mass balance (CMB as the basic premise of the CMB is violated. The conventional CMB is not suitable for accounting chloride mass balance in groundwater systems displaying extreme range of chloride concentrations and complex mixing [3]. Over simplification of karst aquifer systems to suit application of the conventional CMB or 1-D unsaturated modelling as described in Werner [2], is not suitable use of these recharge estimation methods.

Using Novel Laboratory Incubations and Field Experiments to Identify the Source and Fate of Reactive Organic Carbon in an Arsenic-contaminated Aquifer System

Science.gov (United States)

Stahl, M.; Tarek, M. H.; Badruzzaman, B.; Harvey, C. F.

2017-12-01

Characterizing the sources and fate of organic matter (OM) within aquifer systems is key to our understanding of both the broader global carbon cycle as well as the quality of our groundwater resources. The linkage between the subsurface carbon cycle and groundwater quality is perhaps nowhere more apparent than in the aquifer systems of South and Southeast Asia, where the contamination of groundwater with geogenic arsenic (As) is widespread and threatens the health of millions of individuals. OM fuels the biogeochemical processes driving As mobilization within these aquifers, however the source (i.e., modern surface-derived or aged sedimentary OM) of the reactive OM is widely debated. To characterize the sources of OM driving aquifer redox processes we tracked DIC and DOC concentrations and isotopes (stable and radiocarbon) along groundwater flow-paths and beneath an instrumented study pond at a field site in Bangladesh. We also conducted a set of novel groundwater incubation experiments, where we carbon-dated the DOC at the start and end of a experiment in order to determine the age of the OM that was mineralized. Our carbon/isotope balance reveals that aquifer recharge introduces a large quantity of young (i.e. near modern) OM that is efficiently mineralized within the upper few meters of the aquifer, effectively limiting this pool of reactive surface-sourced OM from being transported deeper into the aquifer where significant As mobilization takes place. The OM mineralized past the upper few meters is an aged, sedimentary source. Consistent with our field data, our incubation experiments show that past the upper few meters of the aquifer the reactive DOC is significantly older than the bulk DOC and has an age consistent with sedimentary OM. Combining our novel set of incubation experiments and a carbon/isotope balance along groundwater flow-paths and beneath our study pond we have identified the sources of reactive OM across different aquifer depths in a

Controls on Nitrous Oxide Production in, and Fluxes from a Coastal Aquifer in Long Island, NY, USA

Directory of Open Access Journals (Sweden)

Caitlin Young

2016-11-01

Full Text Available Nitrous oxide (N2O has 265 times greater greenhouse potential than carbon dioxide and its atmospheric concentration has increased by about 20% since industrialization; however, N2O production and emissions from aquatic systems are poorly constrained. To evaluate N2O fluxes associated with meteoric groundwater discharge to coastal zones, we measured N2O concentrations in May and October 2011 from two discharge points of the Upper Glacial aquifer on Long Island, NY, USA. One coastal zone contains only fresh water and the other contains an upper saline zone. N2O concentrations decreased by around 40% for the fresh water and a factor of two for the salt water from May to October, 2011. Fluxes were around 100 to 200 times greater from the freshwater (246 to 448 µmol/m shoreline/day than saltwater aquifer (26.1 to 26.5 µmol/m shoreline/day. N2O concentrations correlate positively with NO3− and dissolved oxygen concentrations and negatively with salinity, dissolved organic carbon (DOC and N2 denitrification concentrations. The smaller saltwater N2O export resulted from DOC enrichment in the upper saline zone, which appears to have driven denitrification to completion, removed N2O, and increased N2 denitrification. DOC concentrations should be considered in global N2O flux estimates for coastal aquifers.

Reactive Multiphase behavior of CO2 in Saline Aquifers beneath the Colorado Plateau

International Nuclear Information System (INIS)

R. G. Allis; J. Moore; S. White

2002-01-01

Gas reservoirs developed within the Colorado Plateau and Southern Rocky Mountains region are natural laboratories for studying the factors that promote long-term storage of CO 2 . They also provide sites for storing additional CO 2 if it can be separated from the flue gases of coal-fired power plants in this part of the U.S.A. These natural reservoirs are developed primarily in sandstones and dolomites; shales, mudstones and anhydrite form seals. In many fields, stacked reservoirs are present, indicating that the gas has migrated up through the section. There are also geologically young travertine deposits at the surface, and CO 2 -charged groundwater and springs in the vicinity of known CO 2 occurrences. These near-surface geological and hydrological features also provide examples of the environmental effects of leakage of CO 2 from reservoirs, and justify further study. During reporting period covered here (the second quarter of Year 2 of the project, i.e. January 1-March 31, 2002), the main achievements were: (1) Field trips to the central Utah and eastern Arizona travertine areas to collect data and water samples to support study of surface CO 2 -rich fluid leakage in these two areas. (2) Partial completion of a manuscript on natural analogues CO 2 leakage from subsurface reservoirs. The remaining section on the chemistry of the fluids is in progress. (3) Improvements to CHEMTOUGH code to incorporate kinetic effects on reaction progress. (4) Submission of two abstracts (based on the above work) to the topical session at the upcoming GSA meeting in Denver titled ''Experimental, Field, and Modeling Studies of Geological Carbon Sequestration''. (5) Submission of paper to upcoming GGHT-6 conference in Kyoto. Co-PI S. White will attend this conference, and will also be involved in three other papers

Strategies for safe exploitation of fresh water through multi-strainer skimming wells in saline groundwater areas

International Nuclear Information System (INIS)

Alam, M.M.; Jaffery, H.M.; Hanif, M.

2005-01-01

Due to growing population of Pakistan, there is a tremendous pressure on our agriculture sector to increase its production to meet the food and fiber requirement. Water is a basic need to increase the agriculture production and to bring more areas under cultivation. The exploitation of groundwater resources is increasing because of limited surface water availability. Statistics indicated that number of public and private tube-wells have increased to more than 5 lacs. Over exploitations of groundwater caused a number of environmental problems including salt water intrusion and increase in the soil and groundwater salinity. A large number of fresh water tube-wells have started pumping saline groundwater in various parts of Pakistan indicating up-coning of saline groundwater in the relatively fresh water aquifers. Use of poor quality groundwater for irrigation is considered as one of the major causes of salinity in the areas of irrigated agriculture. Indiscriminate pumping of the groundwater of marginal quality through skimming fresh water overlain by saline groundwater can not be helpful in the long run. It can add to the root zone salinity and ultimately reduction of crops yield. Mona Reclamation Experimental Project (MREP) is conducting a collaborative research study on 'Root Zone Salinity Management using Fractional Skimming Wells with Pressurized Irrigation' under a research and studies portfolio of the country wide National Drainage Programme (NDP) MREP, IWMI Pakistan and Water Resources Research Institute of PARC are collaborators in this joint research effort. MREP is responsible to specifically address the objective of the study to identify and test a limited number of promising skimming well techniques in the shallow fresh water aquifers which could control the saline water up-coning phenomenon as a consequence of groundwater pumping. Detailed investigations have been done at various locations in the north-central part of Chaj Doab (Sargodha Region) in the

Electrical Resistivity Imaging and the Saline Water Interface in High-Quality Coastal Aquifers

Science.gov (United States)

Costall, A.; Harris, B.; Pigois, J. P.

2018-07-01

Population growth and changing climate continue to impact on the availability of natural resources. Urbanization of vulnerable coastal margins can place serious demands on shallow groundwater. Here, groundwater management requires definition of coastal hydrogeology, particularly the seawater interface. Electrical resistivity imaging (ERI) appears to be ideally suited for this purpose. We investigate challenges and drivers for successful electrical resistivity imaging with field and synthetic experiments. Two decades of seawater intrusion monitoring provide a basis for creating a geo-electrical model suitable for demonstrating the significance of acquisition and inversion parameters on resistivity imaging outcomes. A key observation is that resistivity imaging with combinations of electrode arrays that include dipole-dipole quadrupoles can be configured to illuminate consequential elements of coastal hydrogeology. We extend our analysis of ERI to include a diverse set of hydrogeological settings along more than 100 km of the coastal margin passing the city of Perth, Western Australia. Of particular importance are settings with: (1) a classic seawater wedge in an unconfined aquifer, (2) a shallow unconfined aquifer over an impermeable substrate, and (3) a shallow multi-tiered aquifer system over a conductive impermeable substrate. We also demonstrate a systematic increase in the landward extent of the seawater wedge at sites located progressively closer to the highly urbanized center of Perth. Based on field and synthetic ERI experiments from a broad range of hydrogeological settings, we tabulate current challenges and future directions for this technology. Our research contributes to resolving the globally significant challenge of managing seawater intrusion at vulnerable coastal margins.

Electrical Resistivity Imaging and the Saline Water Interface in High-Quality Coastal Aquifers

Science.gov (United States)

Costall, A.; Harris, B.; Pigois, J. P.

2018-05-01

Population growth and changing climate continue to impact on the availability of natural resources. Urbanization of vulnerable coastal margins can place serious demands on shallow groundwater. Here, groundwater management requires definition of coastal hydrogeology, particularly the seawater interface. Electrical resistivity imaging (ERI) appears to be ideally suited for this purpose. We investigate challenges and drivers for successful electrical resistivity imaging with field and synthetic experiments. Two decades of seawater intrusion monitoring provide a basis for creating a geo-electrical model suitable for demonstrating the significance of acquisition and inversion parameters on resistivity imaging outcomes. A key observation is that resistivity imaging with combinations of electrode arrays that include dipole-dipole quadrupoles can be configured to illuminate consequential elements of coastal hydrogeology. We extend our analysis of ERI to include a diverse set of hydrogeological settings along more than 100 km of the coastal margin passing the city of Perth, Western Australia. Of particular importance are settings with: (1) a classic seawater wedge in an unconfined aquifer, (2) a shallow unconfined aquifer over an impermeable substrate, and (3) a shallow multi-tiered aquifer system over a conductive impermeable substrate. We also demonstrate a systematic increase in the landward extent of the seawater wedge at sites located progressively closer to the highly urbanized center of Perth. Based on field and synthetic ERI experiments from a broad range of hydrogeological settings, we tabulate current challenges and future directions for this technology. Our research contributes to resolving the globally significant challenge of managing seawater intrusion at vulnerable coastal margins.

Identification of the mechanisms and origin of salinization of groundwaters in coastal aquifers by means of isotopic techniques; Identificacion de los mecanismos y del orgien de la salinizacion del agua subterranea en acuiferos costeros mdiante tecnicas isotopicas

Energy Technology Data Exchange (ETDEWEB)

Araguas, L. J.; Quejido, A. J.

2007-07-01

To study the origin of salinity and the mechanisms operating in coastal aquifers, a set of tools is available to determine the essential aspects of the hydrogeological behaviour of the system. these tools are based on the integrated use of hydrochemical parameters (major constituents and trace elements) and isotopic parameters (oxygen, hydrogen, sulfur, carbon, strontium and boron). In addition to the active intrusion of seawater, salinization in coastal areas may be influenced by various human activities that accelerate the degradation of water quality, such as concentrated pumping, intensive farming techniques with return of irrigation water, or reuse of urban and industrial waste water. Characterization of the dominant processes and mechanisms is required for suitable management of the resource and implementation of corrective measures. (Author)

Analysis and Remediation of the Salinized, Damour Coastal (Dolomitic) Limestone Aquifer in Lebanon

NARCIS (Netherlands)

Khadra, W.M.

2017-01-01

Coastal aquifer management has recently emerged as a main scope in groundwater hydrology, especially in arid and semi-arid zones. About two thirds of the human population are currently gathered close to shorelines relying on coastal groundwater resources. Worldwide, these systems are subject to

Constraints of costal aquifer functioning in a deeply antropized area through a multi-isotope fingerprinting (Recife, Brazil)

Science.gov (United States)

Petelet-Giraud, Emmanuelle; Cary, Lise; Bertrand, Guillaume; Hirata, Ricardo; Martins, Veridiana; Montenegro, Suzana; Pauwels, Hélène; Kloppmann, Wolfram; Aquilina, Luc

2014-05-01

The Metropolitan Region of Recife (RMR) went through large changes of water and land uses over the last decades due to an increasing demographic pressure (1.5 M of inhabitants). These evolutions gave rise to numerous environmental consequences, such as a dramatic decline of the water levels, groundwater salinization and contamination. This degradation of natural resources is linked to the increase of water demand that is also punctually amplified by drought periods, inducing the construction of thousands of private wells. Recife city was built on an estuarine area, at the geological limits of the two sedimentary basins of Pernambuco (north of the city) and Paraíba (south of the city) separated by a famous shear zone (the Pernambuco lineament). Tectonic and sedimentary events involved in the genesis and evolution of these basins were mainly controlled by the opening of the Atlantic Ocean leading to the deposition of cretaceous sediments which now constitute the two main exploited aquifers, the Beberibe and Cabo aquifers. These two deep aquiferous formations are topped by the unconfined Boa Viagem aquifer of quaternary sediments. It is the most directly exposed to contamination, since it is connected to mangroves, rivers, estuaries and highly urbanized areas. Both the Beberibe and Cabo aquifers contain large clay levels and are separated by a rather continuous clayed formation which seems to play a consistent role of screen and to interfere in the hydraulic connections between the three aquifers. Previous isotopic studies have shown that recharge processes are similar in the aquifers, suggesting that exchanges may occur and may be modified or amplified by overexploitation. This very complex aquifer system is studied through more than 60 water samples, including some surface water samples from the main rivers. A methodology based on multi-isotopes fingerprinting is applied, including stable isotopes of the water molecule, strontium isotopes, boron isotopes, sulfur

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

Bioremediation of RDX in the vadose zone beneath the Pantex Plant

Energy Technology Data Exchange (ETDEWEB)

Shull, T.L.; Speitel, G.E. Jr.; McKinney, D.C. [Univ. of Texas, Austin, TX (United States). Dept. of Civil Engineering

1999-01-01

The presence of dissolved high explosives (HE), in particular RDX and HMX, is well documented in the perched aquifer beneath the Pantex Plant, but the distribution of HE in the vadose zone has not yet been well defined. Although current remediation activities focus on the contamination in the perched aquifer, eventually regulatory concern is likely to turn to the residual contamination in the vadose zone. Sources of HE include the infiltration of past wastewater discharges from several HE-processing facilities through the ditch drainage system and leachate from former Landfill 3. With limited existing data on the HE distribution in the vadose zone and without preventive action, it must be assumed that residual HE could be leached into infiltrating water, providing a continuing supply of contamination to the perched aquifer. The purpose of this project was to more closely examine the fate and transport of HE in the vadose zone through mathematical modeling and laboratory experimentation. In particular, this report focuses on biodegradation as one possible fate of HE. Biodegradation of RDX in the vadose zone was studied because it is both present in highest concentration and is likely to be of the greatest regulatory concern. This study had several objectives: determine if indigenous soil organisms are capable of RDX biodegradation; determine the impact of electron acceptor availability and nutrient addition on RDX biodegradation; determine the extent of RDX mineralization (i.e., conversion to inorganic carbon) during biodegradation; and estimate the kinetics of RDX biodegradation to provide information for mathematical modeling of fate and transport.

Quality of groundwater in the Denver Basin aquifer system, Colorado, 2003-5

Science.gov (United States)

Musgrove, MaryLynn; Beck, Jennifer A.; Paschke, Suzanne; Bauch, Nancy J.; Mashburn, Shana L.

2014-01-01

Groundwater resources from alluvial and bedrock aquifers of the Denver Basin are critical for municipal, domestic, and agricultural uses in Colorado along the eastern front of the Rocky Mountains. Rapid and widespread urban development, primarily along the western boundary of the Denver Basin, has approximately doubled the population since about 1970, and much of the population depends on groundwater for water supply. As part of the National Water-Quality Assessment Program, the U.S. Geological Survey conducted groundwater-quality studies during 2003–5 in the Denver Basin aquifer system to characterize water quality of shallow groundwater at the water table and of the bedrock aquifers, which are important drinking-water resources. For the Denver Basin, water-quality constituents of concern for human health or because they might otherwise limit use of water include total dissolved solids, fluoride, sulfate, nitrate, iron, manganese, selenium, radon, uranium, arsenic, pesticides, and volatile organic compounds. For the water-table studies, two monitoring-well networks were installed and sampled beneath agricultural (31 wells) and urban (29 wells) land uses at or just below the water table in either alluvial material or near-surface bedrock. For the bedrock-aquifer studies, domestic- and municipal-supply wells completed in the bedrock aquifers were sampled. The bedrock aquifers, stratigraphically from youngest (shallowest) to oldest (deepest), are the Dawson, Denver, Arapahoe, and Laramie-Fox Hills aquifers. The extensive dataset collected from wells completed in the bedrock aquifers (79 samples) provides the opportunity to evaluate factors and processes affecting water quality and to establish a baseline that can be used to characterize future changes in groundwater quality. Groundwater samples were analyzed for inorganic, organic, isotopic, and age-dating constituents and tracers. This report discusses spatial and statistical distributions of chemical constituents

Tidal Pumping-Induced Nutrients Dynamics and Biogeochemical Implications in an Intertidal Aquifer

Science.gov (United States)

Liu, Yi; Jiao, Jiu Jimmy; Liang, Wenzhao; Luo, Xin

2017-12-01

Tidal pumping is a major driving force affecting water exchange between land and sea, biogeochemical reactions in the intertidal aquifer, and nutrient loading to the sea. At a sandy beach of Tolo Harbour, Hong Kong, the nutrient (NH4+, NO2-, NO3-, and PO43-) dynamic in coastal groundwater mixing zone (CGMZ) is found to be fluctuated with tidal oscillation. Nutrient dynamic is mainly controlled by tidal pumping-induced organic matter that serves as a reagent of remineralization in the aquifer. NH4+, NO2-, and PO43- are positively correlated with salinity. Both NH4+ and PO43- have negative correlations with oxidation/reduction potential. NH4+ is the major dissolved inorganic nitrogen species in CGMZ. The adsorption of PO43- onto iron oxides occurs at the deep transition zone with a salinity of 5-10 practical salinity unit (psu), and intensive N-loss occurs in near-surface area with a salinity of 10-25 psu. The biogeochemical reactions, producing PO43- and consuming NH4+, are synergistic effect of remineralization-nitrification-denitrification. In CGMZ, the annual NH4+ loss is estimated to be 4.32 × 105 mol, while the minimum annual PO43- production is estimated to be 2.55 × 104 mol. Applying these rates to the entire Tolo Harbour, the annual NH4+ input to the harbor through the remineralization of organic matters is estimated to be 1.02 × 107 mol. The annual NH4+ loss via nitrification is 1.32 × 107 mol, and the annual PO43- production is 7.76 × 105 mol.

Changes of freshwater-lens thickness in basaltic island aquifers overlain by thick coastal sediments

Science.gov (United States)

Rotzoll, Kolja; Oki, Delwyn S.; El-Kadi, Aly I.

2010-01-01

Freshwater-lens thickness and long-term changes in freshwater volume in coastal aquifers are commonly assessed through repeated measurement of salinity profiles from monitor wells that penetrate into underlying salt water. In Hawaii, the thickest measured freshwater lens is currently 262 m in dike-free, volcanic-rock aquifers that are overlain by thick coastal sediments. The midpoint depth (depth where salinity is 50% salt water) between freshwater and salt water can serve as an indicator for freshwater thickness. Most measured midpoints have risen over the past 40 years, indicating a shrinking lens. The mean rate of rise of the midpoint from 1999–2009 varied locally, with faster rates in highly developed areas (1.0 m/year) and slower rates in less developed areas (0.5 m/year). The thinning of the freshwater lenses is the result of long-term groundwater withdrawal and reduced recharge. Freshwater/salt-water interface locations predicted from measured water levels and the Ghyben-Herzberg principle may be deeper than measured midpoints during some periods and shallower during other periods, although depths may differ up to 100 m in some cases. Moreover, changes in the midpoint are slower than changes in water level. Thus, water levels may not be a reliable indicator of the amount of freshwater in a coastal aquifer.

Mechanism for migration of light nonaqueous phase liquids beneath the water table

International Nuclear Information System (INIS)

Krueger, J.P.; Portman, M.E.

1991-01-01

This paper reports on an interesting transport mechanism may account for the presence of light nonaqueous phase liquid (LNAPL) found beneath the water table in fine-grained aquifers. During the course of two separate site investigations related to suspected releases from underground petroleum storage tanks, LNAPL was found 7 to 10 feet below the regional water table. In both cases, the petroleum was present within a sand seam which was encompassed within a deposit of finer-grained sediments. The presence of LNAPL below the water table is uncommon; typically, LNAPL is found floating on the water table or on the capillary fringe. The occurrence of LNAPL below the water table could have resulted from fluctuating regional water levels which allowed the petroleum to enter the sand when the water table was a lower stage or, alternately, could have occurred as a result of the petroleum depressing the water table beneath the level of the sand. In fine-grained soils where the lateral migration rate is low, the infiltrating LNAPL may depress the water table to significant depth. The LNAPL may float on the phreatic surface with the bulk of its volume beneath the phreatic surface. Once present in the sand and surrounded by water-saturated fine-grained sediments, capillary forces prevent the free movement of the petroleum back across the boundary from the coarse-grained sediments to the fine-grained sediments. Tapping these deposits with a coarser grained filter packed monitoring well releases the LNAPL, which may accumulate to considerable thickness in the monitoring well

Hydrogeochemical characterization and groundwater quality assessment in intruded coastal brine aquifers (Laizhou Bay, China).

Science.gov (United States)

Zhang, Xiaoying; Miao, Jinjie; Hu, Bill X; Liu, Hongwei; Zhang, Hanxiong; Ma, Zhen

2017-09-01

The aquifer in the coastal area of the Laizhou Bay is affected by salinization processes related to intense groundwater exploitation for brine resource and for agriculture irrigation during the last three decades. As a result, the dynamic balances among freshwater, brine, and seawater have been disturbed and the quality of groundwater has deteriorated. To fully understand the groundwater chemical distribution and evolution in the regional aquifers, hydrogeochemical and isotopic studies have been conducted based on the water samples from 102 observation wells. Groundwater levels and salinities in four monitoring wells are as well measured to inspect the general groundwater flow and chemical patterns and seasonal variations. Chemical components such as Na + , K + , Ca 2+ , Mg 2+ , Sr 2+ , Cl - , SO 4 2- , HCO 3 - , NO 3 - , F - , and TDS during the same period are analyzed to explore geochemical evolution, water-rock interactions, sources of salt, nitrate, and fluoride pollution in fresh, brackish, saline, and brine waters. The decreased water levels without typical seasonal variation in the southeast of the study area confirm an over-exploitation of groundwater. The hydrogeochemical characteristics indicate fresh-saline-brine-saline transition pattern from inland to coast where evaporation is a vital factor to control the chemical evolution. The cation exchange processes are occurred at fresh-saline interfaces of mixtures along the hydraulic gradient. Meanwhile, isotopic data indicate that the brine in aquifers was either originated from older meteoric water with mineral dissolution and evaporation or repeatedly evaporation of retained seawater with fresher water recharge and mixing in geological time. Groundwater suitability for drinking is further evaluated according to water quality standard of China. Results reveal high risks of nitrate and fluoride contamination. The elevated nitrate concentration of 560 mg/L, which as high as 28 times of the standard content

Chlorine isotope investigation of natural attenuation of trichloroethene in an aerobic aquifer

International Nuclear Information System (INIS)

Sturchio, N.C.; Heraty, L.J.; Huang, L.; Holt, B.D.; Abrajano, T.A. Jr.; Clausen, J.L.

1998-01-01

Natural attenuation of chlorinated aliphatic hydrocarbons (CAHs) can be an important mechanism for groundwater remediation. It is difficult to determine the effectiveness of natural CAH attenuation from chemical analyses of groundwater samples because mixing, dispersion, and secondary reactions can mask the chemical evidence of attenuation. In this paper, the authors explore the application of stable chlorine isotope ratio measurements as a new tool for evaluating natural attenuation of CAHs. They report stable isotope ratios of chlorine in both trichloroethene (TCE) and inorganic chloride in groundwater from an aerobic aquifer beneath an extensively contaminated industrial site, the Paducah Gaseous Diffusion Plant in western Kentucky. Variations in the concentrations and chlorine isotope ratios of TCE and chloride in the groundwater are consistent with those expected from natural attenuation. These data support a model in which partial TCE degradation occurred in relatively impermeable, clay-rich sediments above the aquifer, and little or no further degradation of TCE occurred within the aquifer. A record of changing conditions within the TCE source area can be inferred from the spatial variation of chlorine isotope ratios for TCE and chloride within the plume

Simulation of saltwater intrusion in a poorly karstified coastal aquifer in Lebanon (Eastern Mediterranean)

Science.gov (United States)

Khadra, Wisam M.; Stuyfzand, Pieter J.

2018-03-01

To date, there has been no agreement on the best way to simulate saltwater intrusion (SWI) in karst aquifers. An equivalent porous medium (EPM) is usually assumed without justification of its applicability. In this paper, SWI in a poorly karstified aquifer in Lebanon is simulated in various ways and compared to measurements. Time series analysis of rainfall and aquifer response is recommended to decide whether quickflow through conduits can be safely ignored. This aids in justifying the selection of the exemplified EPM model. To examine the improvement of SWI representation when discrete features (DFs) are embedded in the model domain, the results of a coupled discrete-continuum (CDC) approach (a hybrid EPM-DF approach) are compared to the EPM model. The two approaches yielded reasonable patterns of hydraulic head and groundwater salinity, which seem trustworthy enough for management purposes. The CDC model also reproduced some local anomalous chloride patterns, being more adaptable with respect to the measurements. It improved the overall accuracy of salinity predictions at wells and better represented the fresh-brackish water interface. Therefore, the CDC approach can be beneficial in modeling SWI in poorly karstified aquifers, and should be compared with the results of the EPM method to decide whether the differences in the outcome at local scale warrant its (more complicated) application. The simulation utilized the SEAWAT code since it is density dependent and public domain, and it enjoys widespread application. Including DFs necessitated manual handling because the selected code has no built-in option for such features.

High resolution numerical investigation on the effect of convective instability on long term CO2 storage in saline aquifers

International Nuclear Information System (INIS)

Lu, C; Lichtner, P C

2007-01-01

CO 2 sequestration (capture, separation, and long term storage) in various geologic media including depleted oil reservoirs, saline aquifers, and oceanic sediments is being considered as a possible solution to reduce green house gas emissions. Dissolution of supercritical CO 2 in formation brines is considered an important storage mechanism to prevent possible leakage. Accurate prediction of the plume dissolution rate and migration is essential. Analytical analysis and numerical experiments have demonstrated that convective instability (Rayleigh instability) has a crucial effect on the dissolution behavior and subsequent mineralization reactions. Global stability analysis indicates that a certain grid resolution is needed to capture the features of density-driven fingering phenomena. For 3-D field scale simulations, high resolution leads to large numbers of grid nodes, unfeasible for a single workstation. In this study, we investigate the effects of convective instability on geologic sequestration of CO 2 by taking advantage of parallel computing using the code PFLOTRAN, a massively parallel 3-D reservoir simulator for modeling subsurface multiphase, multicomponent reactive flow and transport based on continuum scale mass and energy conservation equations. The onset, development and long-term fate of a supercritical CO 2 plume will be resolved with high resolution numerical simulations to investigate the rate of plume dissolution caused by fingering phenomena

Hydrogeological geochemical and isotopic study of the coastal aquifer of Sousse Eastern, Tunisia

International Nuclear Information System (INIS)

Ben-Hamouda, M. F.; Carreira, P.; Marques, J. M.; Eggenkamp, H.

2012-12-01

At Sahel, near one of the seaside resort available in Tunisia, the water quantity and quality is a major problem ever at southern center of Tunisia. The Oued Laya coastal system is no exception. The levels, a shallow aquifer up to depths of about 60 m whose reservoir is mainly formed by Mio-Pliocnesediments (with some gypsum lenses dispersed within the geological formations) and deep aquifer, situated between 100 and 250 m depth, located in the Miocene sandstone formations. The results of geochemical and isotopic studies have shown that groundwater salinity seems not be linked with the increasing water well's abstraction. In contrast, water mineralization seems to acquired by dissolution of minerals in the aquifer system especially halie and gypsum. Besides ion exchange processes play also an important role in the groundwater mineralization. Therefore, it clearly appears that several sources might contribute with different mineralization to the selenization of the aquifer through the natural recharge and also through the return of water irrigation. The contamination of the Mio-Pliocene shallow aquifer by a mixture with seawater is confirmed, and stable isotopes data do not support the hypothesis of mixing with seawater. (Author)

Geophysical investigation of seepage beneath an earthen dam.

Science.gov (United States)

Ikard, S J; Rittgers, J; Revil, A; Mooney, M A

2015-01-01

A hydrogeophysical survey is performed at small earthen dam that overlies a confined aquifer. The structure of the dam has not shown evidence of anomalous seepage internally or through the foundation prior to the survey. However, the surface topography is mounded in a localized zone 150 m downstream, and groundwater discharges from this zone periodically when the reservoir storage is maximum. We use self-potential and electrical resistivity tomography surveys with seismic refraction tomography to (1) determine what underlying hydrogeologic factors, if any, have contributed to the successful long-term operation of the dam without apparent indicators of anomalous seepage through its core and foundation; and (2) investigate the hydraulic connection between the reservoir and the seepage zone to determine whether there exists a potential for this success to be undermined. Geophysical data are informed by hydraulic and geotechnical borehole data. Seismic refraction tomography is performed to determine the geometry of the phreatic surface. The hydro-stratigraphy is mapped with the resistivity data and groundwater flow patterns are determined with self-potential data. A self-potential model is constructed to represent a perpendicular profile extending out from the maximum cross-section of the dam, and self-potential data are inverted to recover the groundwater velocity field. The groundwater flow pattern through the aquifer is controlled by the bedrock topography and a preferential flow pathway exists beneath the dam. It corresponds to a sandy-gravel layer connecting the reservoir to the downstream seepage zone. © 2014, National Ground Water Association.

Contributions of groundwater conditions to soil and water salinization

Science.gov (United States)

Salama, Ramsis B.; Otto, Claus J.; Fitzpatrick, Robert W.

Salinization is the process whereby the concentration of dissolved salts in water and soil is increased due to natural or human-induced processes. Water is lost through one or any combination of four main mechanisms: evaporation, evapotranspiration, hydrolysis, and leakage between aquifers. Salinity increases from catchment divides to the valley floors and in the direction of groundwater flow. Salinization is explained by two main chemical models developed by the authors: weathering and deposition. These models are in agreement with the weathering and depositional geological processes that have formed soils and overburden in the catchments. Five soil-change processes in arid and semi-arid climates are associated with waterlogging and water. In all represented cases, groundwater is the main geological agent for transmitting, accumulating, and discharging salt. At a small catchment scale in South and Western Australia, water is lost through evapotranspiration and hydrolysis. Saline groundwater flows along the beds of the streams and is accumulated in paleochannels, which act as a salt repository, and finally discharges in lakes, where most of the saline groundwater is concentrated. In the hummocky terrains of the Northern Great Plains Region, Canada and USA, the localized recharge and discharge scenarios cause salinization to occur mainly in depressions, in conjunction with the formation of saline soils and seepages. On a regional scale within closed basins, this process can create playas or saline lakes. In the continental aquifers of the rift basins of Sudan, salinity increases along the groundwater flow path and forms a saline zone at the distal end. The saline zone in each rift forms a closed ridge, which coincides with the closed trough of the groundwater-level map. The saline body or bodies were formed by evaporation coupled with alkaline-earth carbonate precipitation and dissolution of capillary salts. Résumé La salinisation est le processus par lequel la

Simulation of the interaction of karstic lakes Magnolia and Brooklyn with the upper Floridan Aquifer, southwestern Clay County, Florida

Science.gov (United States)

Merritt, M.L.

2001-01-01

first of two calibrated models, recharge to the water table, specified as a monthly rate, was set equal to 40 percent of the monthly rainfall rate. The specified rate of inflow to the uppermost stream segment was set equal to outflows from Lake Lowry estimated from lake stage and the 1994-97 rating table. Leakage to the intermediate and Upper Floridan aquifers was assumed to occur from the surficial aquifer system through the confining layers directly beneath deeper parts of the lake bottom. A leakance coefficient value of 0.001 feet per day per foot of thickness was used beneath Lake Magnolia, and a value of 0.005 feet per day per foot of thickness was used beneath most of Lake Brooklyn. With these values, the conductance through the confining layers beneath Lake Brooklyn was about 19 times that beneath Lake Magnolia. The simulated stages of Lake Brooklyn matched the measured stages reasonably well in the early (1957-72) and later (1990-98) parts of the simulation time period, but the match was unsatisfactory in an intermediate time period (1973-89). To resolve this discrepancy, the hypothesis was proposed that undocumented losses of water from Alligator Creek upstream from Lake Brooklyn or from the lake itself occurred between 1973 and 1989 when there was sufficient streamflow. The resulting simulation of lake stages matched the measured lake stages accurately during the entire simulation time period. The model was then revised to incorporate the assumption that only 20 percent of precipitation recharged the water table (the second calibrated model). Recalibration of the model required that leakance values for the confining units under deeper parts of the lakes also be reduced by nearly 50 percent. The stages simulated with the new parameter assumptions, but retaining the assumption of surface-water losses, were an excellent match of the measured values. The stage of Lake Magnolia was also simulated accurately. The results of sensitivity analyses show that simulated s

Different effects of temperature and salinity on permeability reduction by fines migration in Berea sandstone

DEFF Research Database (Denmark)

Rosenbrand, Esther; Kjøller, Claus; Riis, Jacob Fabricius

2015-01-01

Hot water injection into geothermal aquifers is considered in order to store energy seasonally. Berea sandstone is often used as a reference formation to study mechanisms that affect permeability in reservoir sandstones. Both heating of the pore fluid and reduction of the pore fluid salinity can...

Functioning of the Primary Aquifer Relating to the Maider Basin, Morocco: Case of the Ordovician aquifer.

Science.gov (United States)

Ben-said, E.; Boukdir, A.; Mahboub, A.; Younsi, A.; Zitouni, A.; Alili, L.; Ikhmerdi, H.

2018-05-01

The basin of Maider is limited northly by the vast ensemble Oriental Saghro-Ougnate, from the east by the Tafilalet plain, from the west by the oriental Jbel Bani, finally from the south and south-east by the Cretaceous Hamada of Kern-Kem. During last decades, groundwater in the basin of Maider, is confronting degradation in both cases: Quantitative and qualitative, as a result of the drought, the overexploitation and the salinization. The aim of this action research is to understand the current state of water resources in the area of stady. At the end of this work, we can get the following conclusions: the general flow of the ordovician aquifer is always directed from the north to the south-east of the basin by following the principal axes of the wadis:Taghbalt, Hssiya and Fezzou. The recharge of the aquifer is primarily done, either by the underground flow, or by the surface runoff of torrential waters from the upstream of Jbel Saghro. The piezometric anomaly noticed at the level of Ait Saàdane, explained by overexploitation linked to the needs of irrigation water. The physicochemical approach for the Maider basin identifies two essential factors of the salinisation of groundwater: the dissolution of the aquifer which is rich in minerals with high temperature on the one hand, and the decrease of the piezometric surface due to the overexploitation and drought on the other hand.

Assessing Sea Level Rise Impacts on the Surficial Aquifer in the Kennedy Space Center Region

Science.gov (United States)

Xiao, H.; Wang, D.; Hagen, S. C.; Medeiros, S. C.; Warnock, A. M.; Hall, C. R.

2014-12-01

Global sea level rise in the past century due to climate change has been seen at an average rate of approximately 1.7-2.2 mm per year, with an increasing rate over the next century. The increasing SLR rate poses a severe threat to the low-lying land surface and the shallow groundwater system in the Kennedy Space Center in Florida, resulting in saltwater intrusion and groundwater induced flooding. A three-dimensional groundwater flow and salinity transport model is implemented to investigate and evaluate the extent of floods due to rising water table as well as saltwater intrusion. The SEAWAT model is chosen to solve the variable-density groundwater flow and salinity transport governing equations and simulate the regional-scale spatial and temporal evolution of groundwater level and chloride concentration. The horizontal resolution of the model is 50 m, and the vertical domain includes both the Surficial Aquifer and the Floridan Aquifer. The numerical model is calibrated based on the observed hydraulic head and chloride concentration. The potential impacts of sea level rise on saltwater intrusion and groundwater induced flooding are assessed under various sea level rise scenarios. Based on the simulation results, the potential landward movement of saltwater and freshwater fringe is projected. The existing water supply wells are examined overlaid with the projected salinity distribution map. The projected Surficial Aquifer water tables are overlaid with data of high resolution land surface elevation, land use and land cover, and infrastructure to assess the potential impacts of sea level rise. This study provides useful tools for decision making on ecosystem management, water supply planning, and facility management.

Geochemical tracing and hydrogeochemical modelling of water-rock interactions during salinization of alluvial groundwater (Upper Rhine Valley, France)

Energy Technology Data Exchange (ETDEWEB)

Lucas, Y., E-mail: yann.lucas@eost.u-strasbg.fr [Universite de Strasbourg et CNRS, Laboratoire d' Hydrologie et de Geochimie de Strasbourg, Ecole et Observatoire des Sciences de la Terre, 1, rue Blessig, 67084 Strasbourg Cedex (France); Schmitt, A.D., E-mail: anne-desiree.schmitt@univ-fcomte.fr [Universite de Strasbourg et CNRS, Laboratoire d' Hydrologie et de Geochimie de Strasbourg, Ecole et Observatoire des Sciences de la Terre, 1, rue Blessig, 67084 Strasbourg Cedex (France)] [Universite de Franche-Comte et CNRS-UMR 6249, Chrono-Environnement, 16, Route de Gray, 25030 Besancon Cedex (France); Chabaux, F., E-mail: francois.chabaux@eost.u-strasbg.fr [Universite de Strasbourg et CNRS, Laboratoire d' Hydrologie et de Geochimie de Strasbourg, Ecole et Observatoire des Sciences de la Terre, 1, rue Blessig, 67084 Strasbourg Cedex (France); Clement, A.; Fritz, B. [Universite de Strasbourg et CNRS, Laboratoire d' Hydrologie et de Geochimie de Strasbourg, Ecole et Observatoire des Sciences de la Terre, 1, rue Blessig, 67084 Strasbourg Cedex (France); Elsass, Ph. [BRGM, GEODERIS, 1, rue Claude Chappe, 57070 Metz (France); Durand, S. [Universite de Strasbourg et CNRS, Laboratoire d' Hydrologie et de Geochimie de Strasbourg, Ecole et Observatoire des Sciences de la Terre, 1, rue Blessig, 67084 Strasbourg Cedex (France)

2010-11-15

Research highlights: {yields} Major and trace elements along with strontium and uranium isotopic ratios show that groundwater geochemical characteristics along the saline plumes cannot reflect a conservative mixing. {yields} A coupled hydrogeochemical model demonstrates that cationic exchange between alkalis from polluted waters and alkaline-earth elements from montmorillonite present in the host rock of the aquifer is the primary process. {yields} The model requires only a small amount of montmorillonite. {yields} It is necessary to consider the pollution history to explain the important chloride, sodium and calcium concentration modifications. {yields} The model shows that the rapidity of the cationic exchange reactions insures a reversibility of the cation fixation on clays in the aquifer. - Abstract: In the southern Upper Rhine Valley, groundwater has undergone intensive saline pollution caused by the infiltration of mining brines, a consequence of potash extraction carried out during the 20th century. Major and trace elements along with Sr and U isotopic ratios show that groundwater geochemical characteristics along the saline plumes cannot reflect conservative mixing between saline waters resulting from the dissolution of waste heaps and one or more unpolluted end-members. The results imply the occurrence of interactions between host rocks and polluted waters, and they suggest that cationic exchange mechanisms are the primary controlling process. A coupled hydrogeochemical model has been developed with the numerical code KIRMAT, which demonstrates that cationic exchange between alkalis from polluted waters and alkaline-earth elements from montmorillonite present in the host rock of the aquifer is the primary process controlling the geochemical evolution of the groundwater. The model requires only a small amount of montmorillonite (between 0.75% and 2.25%), which is in agreement with the observed mineralogical composition of the aquifer. The model also proves

Distribution of sulphur isotopes of sulphates in groundwaters from the principal artesian aquifer of Florida and the Edwards aquifer of Texas, United States of America

International Nuclear Information System (INIS)

Rightmire, C.T.; Pearson, F.J. Jr.; Back, W.; Rye, R.O.; Hanshaw, B.B.

1974-01-01

New information on the sources of sulphate dissolved in groundwater is obtainable from the measurement of the sulphur isotope composition of sulphates. Field studies in the Floridan aquifer, Florida, and the Edwards aquifer, Texas, show that the use of sulphur isotope data in conjunction with hydrologic and geochemical techniques permits refinements of interpretation. In the Floridan the interpretation of the chemical data, particularly the SO 4 2- concentration and the SO 4 2- /Cl - ratio, leads to the conclusion that recharging maritime rainfall, solution of intraformational gypsum, and mixing with ocean-like saline waters are the sources of sulphate in the groundwater. Sulphur isotope data substantiate this interpretation. The Edwards in the area studied can be separated into two hydrologie units on the basis of water chemistry and aquifer characteristics. The sulphide-free waters in the part of the aquifer upgradient from a distinct sulphide boundary are low in sulphate (less than 100 mg/1) and contain no sulphide. The waters downgradient from that boundary contain greater than 150 mg/1 sulphate and all contain measurable quantities of sulphide. Interpretation of the SO 4 2- concentration and SO 4 2- /Cl ratio on the basis of the Florida study leads to the erroneous conclusion that the solution of intraformational gypsum is again a major source of sulphate in the sulphide-free part of the aquifer. Isotope analyses, however, show that the gypsum is likely to be Permian in age and introduced into the aquifer by the recharge water. The absence of evidence for enrichment in 34 S in the sulphate in the sulphide-bearing portion of the aquifer leads to the possibility of H 2 S migration upgradient from downdip oil fields. (author)

Geothermal characterization of the coastal aquifer near Ravenna (Italy

Directory of Open Access Journals (Sweden)

M. Antonellini

2012-12-01

Full Text Available The coastal aquifer near Ravenna (Italy contains a large volume of groundwater (2,5x109 m3 whose quality has been compromised by sea-water intrusion. Today, the phreatic groundwater is mostly brackish with some lenses of freshwater floating on top of more saline water. This water, although impossible to use as drink-water or for irrigation, is still important to guarantee the health of wetland habitats and especially of the roman historical and coastal pine forests of Ravenna. With the objective of defining the flow pattern within the aquifer and the exchange between surface and ground water, we characterized the temperature distribution in the shallow subsurface by means of a dense network of piezometers. At the same time we had the opportunity to characterize the phreatic aquifer from the geothermal point of view, so that it could eventually be considered for use as a “low enthalpy” heat source. Heat pumps are able to extract heat during the winter and dissipate it during the summer. The temperature of the groundwater in the top layer of the aquifer (surficial zone is sensitive to the changes in atmospheric temperature throughout the year whereas the temperature of the deeper groundwater follows the geothermal gradient (geothermal zone. One of the scopes of the project is to discover at what depth is located the geothermal zone, so that the aquifer has a constant temperature throughout the year. A constant temperature is needed for storage of heat at low enthalpy. The thickness of the surficial zone and the temperature at the top of the geothermal zone are essentially related to land use, distance from the sea, sediment type, and amount of interaction between surface and groundwater. A knowledge of these factors allows to better exploit the geothermal potential of the aquifer when choosing the optimal placement of the heat pumps.

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.

Management of saline soils in Israel

International Nuclear Information System (INIS)

Rawitz, E.

1983-01-01

The main soil salinity problem in Israel is the danger of gradual salinization as a result of excessively efficient water management. Aquifer management is aimed at preventing flow of groundwater into the ocean, causing a creeping salinization at a rate of about 2 ppm per year. Successful efforts to improve irrigation efficiency brought with them the danger of salt accumulation in the soil. A ten-year monitoring programme carried out by the Irrigation Extension Service at 250 sampling sites showed that appreciable salt accumulation indeed occurred during the rainless irrigation season. However, where annual rainfall is more than about 350 mm this salt accumulation is adequately leached out of the root zone by the winter rains. Soil salinity in the autumn is typically two to three times that in the spring, a level which does not affect yields adversely. In the drier regions of the country long-term increasing soil salinity has been observed, and leaching is required. This is generally accomplished during the pre-irrigation given in the spring, whose size is determined by the rainfall amount of the preceding winter. The increasing need to utilize brackish groundwater and recycled sewage effluent requires special measures, which have so far been successful. In particular, drip irrigation with its high average soil-water potential regime and partial wetting of the soil volume has achieved high yields under adverse conditions. However, the long-term trend of water-quality deterioration is unavoidable under present conditions, and will eventually necessitate either major changes in agricultural patterns or the provision of desalinated water for dilution of the irrigation water. (author)

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

Potentiometric surface of the Upper Floridan aquifer in Florida and parts of Georgia, South Carolina, and Alabama, May – June 2010

Science.gov (United States)

Kinnaman, Sandra L.; Dixon, Joann F.

2011-01-01

The Floridan aquifer system covers nearly 100,000 square miles in the southeastern United States throughout Florida and in parts of Georgia, South Carolina, and Alabama, and is one of the most productive aquifers in the world (Miller, 1990). This sequence of carbonate rocks is hydraulically connected and is over 300 feet thick in south Florida and thins toward the north. Typically, this sequence is subdivided into the Upper Floridan aquifer, the middle confining unit, and the Lower Floridan aquifer. The majority of freshwater is contained in the Upper Floridan aquifer and is used for water supply (Miller, 1986). The Lower Floridan aquifer contains fresh to brackish water in northeastern Florida and Georgia, while in south Florida it is saline. The potentiometric surface of the Upper Floridan aquifer in May–June 2010 shown on this map was constructed as part of the U.S. Geological Survey Floridan Aquifer System Groundwater Availability Study (U.S. Geological Survey database, 2011). Previous synoptic measurements and regional potentiometric maps of the Upper Floridan aquifer were prepared for May 1980 (Johnston and others, 1981) and May 1985 (Bush and others, 1986) as part of the Floridan Regional Aquifer System Analysis.

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

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

Restoration of Wadi Aquifers by Artificial Recharge with Treated Waste Water

KAUST Repository

Missimer, Thomas M.

2012-04-26

Fresh water resources within the Kingdom of Saudi Arabia are a rare and precious commodity that must be managed within a context of integrated water management. Wadi aquifers contain a high percentage of the naturally occurring fresh groundwater in the Kingdom. This resource is currently overused and has become depleted or contaminated at many locations. One resource that could be used to restore or enhance the fresh water resources within wadi aquifers is treated municipal waste water (reclaimed water). Each year about 80 percent of the country\\'s treated municipal waste water is discharged to waste without any beneficial use. These discharges not only represent a lost water resource, but also create a number of adverse environmental impacts, 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 and recovery (ARR) systems that will be able to treat the impaired-quality water, store it until needed, and allow recovery of the water for transmittal to areas in demand. Full-engineered ARR systems can be designed at high capacities within wadi aquifer systems that can operate in concert with the natural role of wadis, while providing the required functions of additional treatment, storage and recovery of reclaimed water, while reducing the need to develop additional, energy-intensive desalination to meet new water supply demands. © 2012, The Author(s). Ground Water © 2012, National Ground Water Association.

Restoration of wadi aquifers by artificial recharge with treated waste water.

Science.gov (United States)

Missimer, Thomas M; Drewes, Jörg E; Amy, Gary; Maliva, Robert G; Keller, Stephanie

2012-01-01

Fresh water resources within the Kingdom of Saudi Arabia are a rare and precious commodity that must be managed within a context of integrated water management. Wadi aquifers contain a high percentage of the naturally occurring fresh groundwater in the Kingdom. This resource is currently overused and has become depleted or contaminated at many locations. One resource that could be used to restore or enhance the fresh water resources within wadi aquifers is treated municipal waste water (reclaimed water). Each year about 80 percent of the country's treated municipal waste water is discharged to waste without any beneficial use. These discharges not only represent a lost water resource, but also create a number of adverse environmental impacts, 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 and recovery (ARR) systems that will be able to treat the impaired-quality water, store it until needed, and allow recovery of the water for transmittal to areas in demand. Full-engineered ARR systems can be designed at high capacities within wadi aquifer systems that can operate in concert with the natural role of wadis, while providing the required functions of additional treatment, storage and recovery of reclaimed water, while reducing the need to develop additional, energy-intensive desalination to meet new water supply demands. © 2012, The Author(s). Ground Water © 2012, National Ground Water Association.

Soil Fertility, Salinity and Nematode Diversity Influenced by Tamarix ramosissima in Different Habitats in an Arid Desert Oasis

Science.gov (United States)

Yong-zhong, Su; Xue-fen, Wang; Rong, Yang; Xiao, Yang; Wen-jie, Liu

2012-08-01

The aim of this paper was to assess the influence of tamarisk shrubs on soil fertility, salinity and nematode communities in various habitats located in an arid desert-oasis region in northwest China. Three habitats were studied: sand dune, riparian zone and saline meadow, where tamarisk shrubs have been established in recent decades in order to vegetation restoration used as desertification control and saline land rehabilitation projects and become the dominant plant community. The parameters measured include soil organic carbon (SOC), total nitrogen, available phosphorus (P) and potassium (K), pH, salt component, and nematode community characteristics. Enrichment ratios (a comparison of the soil measurements between soils under canopy and in the open interspaces) for soil nutrients and salinity were used to evaluate fertility and salinity islands underneath the tamarisk shrubs. The soil nematode community was used as a biological indicator of soil condition. SOC and available P and K were higher beneath the plant canopy than in the open interspaces outside that canopy. The enrichment ratios for SOC and nutrients were highest for the sand dune habitat and tamarisk shrubs clearly created islands of greater salinity under the canopies. Nematode abundance per 100 g dry soil varied considerably between the locations and habitats, with the highest abundance found in sand dune and the lowest in saline meadow. A significantly higher nematode abundance and a lower trophic diversity were found in soils under the canopy compared to the soils in the open interspaces. With the exception of saline meadow, the abundance of bacterivores increased and fungivores decreased under the canopy relative to the open interspaces, and bacterivores dominated under the canopies in the sand dune and riparian habitats. The enrichment ratios for salinity were higher than for fertility, suggesting that improved soil fertility can not limit the impact of salinization beneath tamarisk shrubs. The

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).

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

Combined use of frequency‐domain electromagnetic and electrical resistivity surveys to delineate the freshwater/saltwater interface near saline lakes in the Nebraska Sand Hills, Nebraska, USA

Science.gov (United States)

Ong, John T.; White, Eric A.; Lane, John W.; Halihan, Todd; Zlotnik, Vitaly A; Butler, Dwain K.

2009-01-01

We investigate the use of frequency‐domain electromagnetic (FDEM) and electrical resistivity (ER) surveys for rapid and detailed characterization of the direction of lake‐aquifer fluxes and the configuration of salt plumes generated from saline lakes. This methodology was developed and applied at several lakes in the Nebraska Sand Hills, Nebraska, in an area with both freshwater and saline lakes hydraulically connected to the freshwater surficial aquifer. The FDEM survey was conducted by mounting the instrument on a fiberglass cart towed by an all‐terrain vehicle. The towed FDEM surveys covered about 25 km per day and served as a reconnaissance method for choosing locations for the more quantitative and detailed ER surveys. Around the saline lakes, areas with high electrical conductivity are consistent with the regional direction of ground‐water flow. Lower electrical conductivity was measured around the freshwater lakes with anomalies correlating to a paleovalley axis inferred from previous studies. The efficacy of this geophysical approach is attributed to: (1) significant contrast in electrical conductivity between freshwater and saltwater, (2) near‐surface location of the freshwater/saltwater interface, (3) minimal cultural interference, and (4) relative homogeneity of the aquifer materials.

Resistivity method contribution in determining of fault zone and hydro-geophysical characteristics of carbonate aquifer, eastern desert, Egypt

Science.gov (United States)

Ammar, A. I.; Kamal, K. A.

2018-03-01

Determination of fault zone and hydro-geophysical characteristics of the fractured aquifers are complicated, because their fractures are controlled by different factors. Therefore, 60 VESs were carried out as well as 17 productive wells for determining the locations of the fault zones and the characteristics of the carbonate aquifer at the eastern desert, Egypt. The general curve type of the recorded rock units was QKH. These curves were used in delineating the zones of faults according to the application of the new assumptions. The main aquifer was included at end of the K-curve type and front of the H-curve type. The subsurface layers classified into seven different geoelectric layers. The fractured shaly limestone and fractured limestone layers were the main aquifer and their resistivity changed from low to medium (11-93 Ω m). The hydro-geophysical properties of this aquifer such as the areas of very high, high, and intermediate fracture densities of high groundwater accumulations, salinity, shale content, porosity distribution, and recharging and flowing of groundwater were determined. The statistical analysis appeared that depending of aquifer resistivity on the water salinities (T.D.S.) and water resistivities add to the fracture density and shale content. The T.D.S. increasing were controlled by Na+, Cl-, Ca2+, Mg2+, and then (SO4)2-, respectively. The porosity was calculated and its average value was 19%. The hydrochemical analysis of groundwater appeared that its type was brackish and the arrangements of cation concentrations were Na+ > Ca2+ > Mg2+ > K+ and anion concentrations were Cl- > (SO4)2- > HCO3 - > CO3 -. The groundwater was characterized by sodium-bicarbonate and sodium-sulfate genetic water types and meteoric in origin. Hence, it can use the DC-resistivity method in delineating the fault zone and determining the hydro-geophysical characteristics of the fractured aquifer with taking into account the quality of measurements and interpretation.

Empirical tools for simulating salinity in the estuaries in Everglades National Park, Florida

Science.gov (United States)

Marshall, F. E.; Smith, D. T.; Nickerson, D. M.

2011-12-01

Salinity in a shallow estuary is affected by upland freshwater inputs (surface runoff, stream/canal flows, groundwater), atmospheric processes (precipitation, evaporation), marine connectivity, and wind patterns. In Everglades National Park (ENP) in South Florida, the unique Everglades ecosystem exists as an interconnected system of fresh, brackish, and salt water marshes, mangroves, and open water. For this effort a coastal aquifer conceptual model of the Everglades hydrologic system was used with traditional correlation and regression hydrologic techniques to create a series of multiple linear regression (MLR) salinity models from observed hydrologic, marine, and weather data. The 37 ENP MLR salinity models cover most of the estuarine areas of ENP and produce daily salinity simulations that are capable of estimating 65-80% of the daily variability in salinity depending upon the model. The Root Mean Squared Error is typically about 2-4 salinity units, and there is little bias in the predictions. However, the absolute error of a model prediction in the nearshore embayments and the mangrove zone of Florida Bay may be relatively large for a particular daily simulation during the seasonal transitions. Comparisons show that the models group regionally by similar independent variables and salinity regimes. The MLR salinity models have approximately the same expected range of simulation accuracy and error as higher spatial resolution salinity models.

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.

Hydrochemical Characteristics and Formation of the Saline or Salty Springs in Eastern Sichuan Basin of China

Science.gov (United States)

Zhou, X.

2017-12-01

Saline or salty springs provide important information on the hydrogeochemical processes and hydrology within subsurface aquifers. More than 20 saline and salty springs occur in the core of anticlines in the eastern Sichuan Basin in southwestern China where the Lower and Middle Triassic carbonates outcrop. Water samples of 8 saline and salty springs (including one saline hot spring) were collected for analyses of the major and minor constituents, trace elements and stable oxygen and hydrogen isotopes. The TDS of the springs range from 4 to 83 g/L, and they are mainly of Cl-Na type. Sr, Ba and Li are the predominant trace elements. The δ2H and δ18O of the water samples indicate that they are of meteoric origin. The source of salinity of the springs originates from dissolution of minerals in the carbonates, including halite, gypsum, calcite and dolomite. The formation mechanism of the springs is that groundwater receives recharge from infiltration of precipitation, undergoes shallow or deep circulation in the core of the anticline and incongruent dissolution of the salt-bearing carbonates occurs, and emerges in the river valley in the form of springs with relatively high TDS. The 8 springs can be classified into 4 springs of shallow groundwater circulation and 4 springs of deep groundwater circulation according to the depth of groundwater circulation, 7 springs of normal temperature and 1 hot spring according to temperature. There are also 2 up-flow springs: the carbonate aquifers are overlain by relatively impervious sandstone and shale, groundwater may flows up to the ground surface through the local portion of the overlying aquiclude where fractures were relatively well developed, and emerges as an up-flow spring. Knowledge of the hydrochemical characteristics and the geneses of the saline and salty springs are of important significance for the utilization and preservation of the springs.

Using radon-222 to study coastal groundwater/surface-water interaction in the Crau coastal aquifer (southeastern France)

Science.gov (United States)

Mayer, Adriano; Nguyen, Bach Thao; Banton, Olivier

2016-11-01

Radon has been used to determine groundwater velocity and groundwater discharge into wetlands at the southern downstream boundary of the Crau aquifer, southeastern France. This aquifer constitutes an important high-quality freshwater resource exploited for agriculture, industry and human consumption. An increase in salinity occurs close to the sea, highlighting the need to investigate the water balance and groundwater behavior. Darcy velocity was estimated using radon activities in well waters according to the Hamada "single-well method" (involving comparison with radon in groundwater in the aquifer itself). Measurements done at three depths (7, 15 and 21 m) provided velocity ranging from a few mm/day to more than 20 cm/day, with highest velocities observed at the 15-m depth. Resulting hydraulic conductivities agree with the known geology. Waters showing high radon activity and high salinity were found near the presumed shoreline at 3,000 years BP, highlighting the presence of ancient saltwater. Radon activity has also been measured in canals, rivers and ponds, to trace groundwater discharges and evaluate water balance. A model of the radon spatial evolution explains the observed radon activities. Groundwater discharge to surface water is low in pond waters (4 % of total inputs) but significant in canals (55 l/m2/day).

Separation and capture of CO2 from large stationary sources and sequestration in geological formations--coalbeds and deep saline aquifers.

Science.gov (United States)

White, Curt M; Strazisar, Brian R; Granite, Evan J; Hoffman, James S; Pennline, Henry W

2003-06-01

commercial CO2 capture facilities at electric power-generating stations based on the use of monoethanolamine are described, as is the Rectisol process used by Dakota Gasification to separate and capture CO2 from a coal gasifier. Two technologies for storage of the captured CO2 are reviewed--sequestration in deep unmineable coalbeds with concomitant recovery of CH4 and sequestration in deep saline aquifers. Key issues for both of these techniques include estimating the potential storage capacity, the storage integrity, and the physical and chemical processes that are initiated by injecting CO2 underground. Recent studies using computer modeling as well as laboratory and field experimentation are presented here. In addition, several projects have been initiated in which CO2 is injected into a deep coal seam or saline aquifer. The current status of several such projects is discussed. Included is a commercial-scale project in which a million tons of CO2 are injected annually into an aquifer under the North Sea in Norway. The review makes the case that this can all be accomplished safely with off-the-shelf technologies. However, substantial research and development must be performed to reduce the cost, decrease the risks, and increase the safety of sequestration technologies. This review also includes discussion of possible problems related to deep injection of CO2. There are safety concerns that need to be addressed because of the possibilities of leakage to the surface and induced seismic activity. These issues are presented along with a case study of a similar incident in the past. It is clear that monitoring and verification of storage will be a crucial part of all geological sequestration practices so that such problems may be avoided. Available techniques include direct measurement of CO2 and CH4 surface soil fluxes, the use of chemical tracers, and underground 4-D seismic monitoring. Ten new hypotheses were formulated to describe what happens when CO2 is pumped into a coal

Considerations in the extraction of uranium from a fresh-water aquifer - Miocene Oakville Sandstone, south Texas

International Nuclear Information System (INIS)

Henry, C.D.; Galloway, W.E.; Smith, G.E.

1982-01-01

The Miocene Oakville Sandstone is a major aquifer and uranium host beneath the Texas Coastal Plain. Present and future uranium mining by either surface or in situ methods could affect the availability and quality of Oakville ground water unless the mining is designed properly. Possible effects of mining, potential natural mitigation of these effects, and approaches to minimizing the impact of mining on the aquifer system are discussed. Both solution and surface mining may affect the availability of ground water by altering recharge characteristics and permeability. Because the volume of the aquifer affected by mining is small compared with its total volume, availability of Oakville ground water will probably not be reduced significantly, except in wells immediately adjacent to a mine. Mining may affect the quality of ground water by introducing chemicals that are not indigenous to the aquifer or by inducing chemical reactions that do not occur naturally or that occur at much slower rates. Most mining companies no longer use concentrated, ammonium-based leaches because of known problems in restoring water to its original chemistry. Natural and induced release of trace elements such as molybdenum is known to occur, but the geochemical controls on mobility and potential mitigating reactions in the aquifer are poorly understood. Because the affected aquifer volume is small, any deterioration of water quality will probably be localized. Observations and recommendations are presented on: regional and local baseline studies, determination of aquifer sensitivity, methods and goals of monitoring during and after mining, and need for research on poorly understood aspects of mining impact. Such impacts include chemical reactions and processes that affect the long-term release of trace elements

Planning report for the Gulf Coast Regional Aquifer-System Analysis in the Gulf of Mexico coastal plain, United States

Science.gov (United States)

Grubb, Hayes F.

1984-01-01

Large quantities of water for municipal, industrial and agriculture use are supplied from the aquifers in Tertiary and younger sediments over an area of about 225,000 square miles in the Coastal Plain of Alabama, Arkansas, Florida, Illinois, Kentucky, Louisiana, Mississippi, Missouri, Tennessee, and Texas. Three regional aquifer systems, the Mississippi Embayment aquifer system, the Coastal Lowlands aquifer system, and the Texas Coastal Uplands aquifer system have been developed to varying degrees throughout the area. A variety of problems has resulted from development such as movement of the saline-freshwater interface into parts of aquifers that were previously fresh, lowering of the potentiometric surface with resulting increases in pumping lift, and land-surface subsidence due to the compaction of clays within the aquifer. Increased demand for ground water is anticipated to meet the needs of urban growth, expanded energy development, and growth of irrigated agriculture. The U. S. Geological Survey initiated an eightyear study in 1981 to define the geohydrologic framework, describe the chemistry of the ground water, and to analyze the regional ground-water flow patterns. The objectives, plan, and organization of the study are described in this report and the major tasks to be undertaken are outlined.

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

Aquifer Characteristics Data Report for the Weldon Spring Site chemical plant/raffinate pits and vicinity properties for the Weldon Spring Site Remedial Action Project, Weldon Spring, Missouri

International Nuclear Information System (INIS)

1990-11-01

This report describes the procedures and methods used, and presents the results of physical testing performed, to characterize the hydraulic properties of the shallow Mississippian-Devonian aquifer beneath the Weldon Spring chemical plant, raffinate pits, and vicinity properties. The aquifer of concern is composed of saturated rocks of the Burlington-Keokuk Limestone which constitutes the upper portion of the Mississippian-Devonian aquifer. This aquifer is a heterogeneous anisotropic medium which can be described in terms of diffuse Darcian flow overlain by high porosity discrete flow zones and conduits. Average hydraulic conductivity for all wells tested is 9.6E-02 meters/day (3.1E-01 feet/day). High hydraulic conductivity values are representative of discrete flow in the fractured and weathered zones in the upper Burlington-Keokuk Limestone. They indicate heterogeneities within the Mississippian-Devonian aquifer. Aquifer heterogeneity in the horizontal plane is believed to be randomly distributed and is a function of fracture spacing, solution voids, and preglacial weathering phenomena. Relatively high hydraulic conductivities in deeper portions of the aquifer are though to be due to the presence of widely spaced fractures. 44 refs., 27 figs., 9 tabs

Geophysical characterization of saltwater intrusion in a coastal aquifer: The case of Martil-Alila plain (North Morocco)

Science.gov (United States)

Himi, Mahjoub; Tapias, Josefiina; Benabdelouahab, Sara; Salhi, Adil; Rivero, Luis; Elgettafi, Mohamed; El Mandour, Abdenabi; Stitou, Jamal; Casas, Albert

2017-02-01

Several factors can affect the quantity and the quality of groundwater resources, but in coastal aquifers seawater intrusion is often the most significant issue regarding freshwater supply. Further, saltwater intrusion is a worldwide issue because about seventy percent of the world's population lives in coastal regions. Generally, fresh groundwater not affected by saltwater intrusion is characterized by low salinity and therefore low electrical conductivity (EC) values. Consequently, high values of EC in groundwater along the coastline are usually associated to seawater intrusion. This effect is amplified if the coastal aquifer is overexploited with a subsequent gradual displacement of the freshwater-saltwater interface towards the continent. Delineation of marine intrusion in coastal aquifers has traditionally relied upon observation wells and collection of water samples. This approach may miss important hydrologic features related to saltwater intrusion in areas where access is difficult and where wells are widely spaced. Consequently, the scarcity of sampling points and sometimes their total absence makes the number of data available limited and most of the time not representative for mapping the spatial and temporal variability of groundwater salinity. In this study, we use a series of geophysical methods for characterizing the aquifer geometry and the extension of saltwater intrusion in the Martil-Alila coastal region (Morocco) as a complement to geological and hydrogeochemical data. For this reason, we carried out three geophysical surveys: Gravity, Electrical Resistivity and Frequency Domain Electromagnetic. The geometry of the basin has been determined from the interpretation of a detailed gravity survey. Electrical resistivity models derived from vertical electrical soundings allowed to characterize the vertical and the lateral extensions of aquifer formations. Finally, frequency domain electromagnetic methods allowed delineating the extension of the

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

Hydrogeologic and Hydraulic Characterization of the Surficial Aquifer System, and Origin of High Salinity Groundwater, Palm Beach County, Florida

Science.gov (United States)

Reese, Ronald S.; Wacker, Michael A.

2009-01-01

Previous studies of the hydrogeology of the surficial aquifer system in Palm Beach County, Florida, have focused mostly on the eastern one-half to one-third of the county in the more densely populated coastal areas. These studies have not placed the hydrogeology in a framework in which stratigraphic units in this complex aquifer system are defined and correlated between wells. Interest in the surficial aquifer system has increased because of population growth, westward expansion of urbanized areas, and increased utilization of surface-water resources in the central and western areas of the county. In 2004, the U.S. Geological Survey, in cooperation with the South Florida Water Management District, initiated an investigation to delineate the hydrogeologic framework of the surficial aquifer system in Palm Beach County, based on a lithostratigraphic framework, and to evaluate hydraulic properties and characteristics of units and permeable zones within this framework. A lithostratigraphic framework was delineated by correlating markers between all wells with data available based primarily on borehole natural gamma-ray geophysical log signatures and secondarily, lithologic characteristics. These correlation markers approximately correspond to important lithostratigraphic unit boundaries. Using the markers as guides to their boundaries, the surficial aquifer system was divided into three main permeable zones or subaquifers, which are designated, from shallowest to deepest, zones 1, 2, and 3. Zone 1 is above the Tamiami Formation in the Anastasia and Fort Thompson Formations. Zone 2 primarily is in the upper part or Pinecrest Sand Member of the Tamiami Formation, and zone 3 is in the Ochopee Limestone Member of the Tamiami Formation or its correlative equivalent. Differences in the lithologic character exist between these three zones, and these differences commonly include differences in the nature of the pore space. Zone 1 attains its greatest thickness (50 feet or more

Soil salinization in the agricultural lands of Rhodope District, northeastern Greece.

Science.gov (United States)

Pisinaras, V; Tsihrintzis, V A; Petalas, C; Ouzounis, K

2010-07-01

The objective of this study was to identify seasonal and spatial trends and soil salinization patterns in a part of Rhodope District irrigated land, northeastern Greece, located east of Vistonis Lagoon. The study area is irrigated from a coastal aquifer, where salt water intrusion occurs because of extensive groundwater withdrawals. Fourteen monitoring sites were established in harvest fields in the study area, where soil samples were collected. Electrical conductivity (ECe), pH, and ion concentrations were determined in the saturated paste extract of the soil samples in the laboratory using standard methods. A clear tendency was observed for ECe to increase from April to September, i.e., within the irrigation period, indicating the effect of saline groundwater to soil. In the last years, the change from moderately sensitive (e.g., corn) to moderately tolerant crops (e.g., cotton) in the south part of the study area indicates the impacts of soil salinity. The study proposes management methods to alleviate this problem.

Regional-scale airborne electromagnetic surveying of the Yucatan karst aquifer (Mexico): geological and hydrogeological interpretation

DEFF Research Database (Denmark)

Gondwe, Bibi Ruth Neuman; Ottowitz, David; Supper, Robert

2012-01-01

-spectral remote sensing imagery, shuttle radar topography data and frequency-domain airborne electromagnetic (AEM) survey data were used to map karst-aquifer structure on the Yucatan Peninsula, Mexico. Anomalous AEM responses correlated with topographic features and anomalous spectral reflectance of the terrain...... as ejecta from the Chicxulub impact (Cretaceous/Paleogene boundary), based on similar resistivity signatures found in borehole logs. Due to limited sensitivity of the AEM survey, the subsurface configuration beneath the low-resistivity layer could not be unambiguously determined. AEM measurements combined...

Transition from confined to phreatic conditions as the factor controlling salinization and change in redox state, Upper subaquifer of the Judea Group, Israel

Science.gov (United States)

Gavrieli, Ittai; Burg, Avi; Guttman, Joseph

2002-08-01

An increase in salinity and change from oxic to anoxic conditions are observed in the Upper subaquifer of the Judea Group in the Kefar Uriyya pumping field at the western foothills of the Judea Mountains, Israel. Hydrogeological data indicate that the change, which occurs over a distance of only a few kilometers, coincides with a transition from confined to phreatic conditions in the aquifer. The deterioration in the water quality is explained as a result of seepage of more saline, organic-rich water from above, into the phreatic "roofed" part of the aquifer. The latter is derived from the bituminous chalky rocks of the Mount Scopus Group, which confine the aquifer in its southeastern part. In this confined part, water in perched horizons within the Mount Scopus Group cannot leak down and flow westward while leaching organic matter and accumulating salts. However, upon reaching the transition area from confined to phreatic conditions, seepage to the Judea Upper subaquifer is possible, thereby allowing it to be defined as a leaky aquifer. The incoming organic matter consumes the dissolved oxygen and allows bacterial sulfate reduction. The latter accounts for the H2S in the aquifer, as indicated by sulfur isotopic analyses of coexisting sulfate and sulfide. Thus, from an aquifer management point of view, in order to maintain the high quality of the water in the confined southeastern part of the Kefar Uriyya field, care should be taken not to draw the confined-roofed transition area further east by over pumping.

Interaction of Aquifer and River-Canal Network near Well Field.

Science.gov (United States)

Ghosh, Narayan C; Mishra, Govinda C; Sandhu, Cornelius S S; Grischek, Thomas; Singh, Vikrant V

2015-01-01

The article presents semi-analytical mathematical models to asses (1) enhancements of seepage from a canal and (2) induced flow from a partially penetrating river in an unconfined aquifer consequent to groundwater withdrawal in a well field in the vicinity of the river and canal. The nonlinear exponential relation between seepage from a canal reach and hydraulic head in the aquifer beneath the canal reach is used for quantifying seepage from the canal reach. Hantush's (1967) basic solution for water table rise due to recharge from a rectangular spreading basin in absence of pumping well is used for generating unit pulse response function coefficients for water table rise in the aquifer. Duhamel's convolution theory and method of superposition are applied to obtain water table position due to pumping and recharge from different canal reaches. Hunt's (1999) basic solution for river depletion due to constant pumping from a well in the vicinity of a partially penetrating river is used to generate unit pulse response function coefficients. Applying convolution technique and superposition, treating the recharge from canal reaches as recharge through conceptual injection wells, river depletion consequent to variable pumping and recharge is quantified. The integrated model is applied to a case study in Haridwar (India). The well field consists of 22 pumping wells located in the vicinity of a perennial river and a canal network. The river bank filtrate portion consequent to pumping is quantified. © 2014, National GroundWater Association.

Ground-water quality beneath an urban residential and commercial area, Montgomery, Alabama, 1999-2000

Science.gov (United States)

Robinson, James L.

2002-01-01

The Black Warrior River aquifer, which is composed of the Coker, Gordo, and Eutaw Formations, supplies more than 50 percent of the ground water used for public water supply in the Mobile River Basin. The city of Montgomery, Alabama, is partially built upon a recharge area for the Black Warrior River aquifer, and is one of many major population centers that depend on the Black Warrior River aquifer for public water supply. To represent the baseline ground-water quality in the Black Warrior River aquifer, water samples were collected from 30 wells located in a low-density residential or rural setting; 9 wells were completed in the Coker Formation, 9 wells in the Gordo Formation, and 12 wells in the Eutaw Formation. To describe the ground-water quality beneath Montgomery, Alabama, water samples also were collected from 30 wells located in residential and commercial areas of Montgomery, Alabama; 16 wells were completed in the Eutaw Formation, 8 wells in alluvial deposits, and 6 wells in terrace deposits. The alluvial and terrace deposits directly overlie the Eutaw Formation with little or no hydraulic separation. Ground-water samples collected from both the rural and urban wells were analyzed for physical properties, major ions, nutrients, metals, volatile organic compounds, and pesticides. Samples from the urban wells also were analyzed for bacteria, chlorofluorocarbons, dissolved gases, and sulfur hexafluoride. Ground-water quality beneath the urban area was compared to baseline water quality in the Black Warrior River aquifer.Compared to the rural wells, ground-water samples from urban wells contained greater concentrations or more frequent detections of chloride and nitrate, and the trace metals aluminium, chromium, cobalt, copper, nickel, and zinc. Pesticides and volatile organic compounds were detected more frequently and in greater concentrations in ground-water samples collected from urban wells than in ground-water samples from rural wells.The Spearman rho

Geochemical effects of CO2 sequestration in sandstones under simulated in situ conditions of deep saline aquifers

International Nuclear Information System (INIS)

Wigand, M.; Carey, J.W.; Schuett, H.; Spangenberg, E.; Erzinger, J.

2008-01-01

The geochemical effects of brine and supercritical CO 2 (SCCO 2 ) on reservoir rocks from deep (1500-2000 m) saline aquifers were examined via experimental simulation at in situ conditions. Dry sandstone samples were mounted in a triaxial cell and autoclave system, evacuated, and saturated with 1 M NaCl solution. The brine-rock system was allowed to react at 30 MPa confining pressure, 15 MPa pore fluid pressure, and 60 deg. C while SCCO 2 was injected at a pressure gradient of 1-2 MPa. The experiment was conducted for a period of 1496 h, during which fluids were periodically sampled and analyzed. The pH measured in partially degassed fluid samples at 25 deg. C decreased from a starting value of 7.0-4.3 (9 days) and finally 5.1 after saturation with SCCO 2 . Fluid analyses indicate that most of the major (e.g. Ca, Mg, Fe, Mn) and trace elements (e.g. Sr, Ba, Pb) of the sandstone increase in concentration during the reaction with brine and SCCO 2 . These results are supported by scanning electron microscopy which indicates dissolution of dolomite cement, K-feldspar, and albite. In addition to dissolution reactions the formation of montmorillonite was observed. By adjusting surface area and reaction rates of dissolution and precipitation, geochemical modeling of the experiments could reproduce long-term trends in solution chemistry and indicated limited rates of dissolution as the system remained strongly undersaturated with most minerals, including carbonates. The geochemical models could not account for decreases in concentration of some elements, changes in solution composition resulting from changes in imposed pressure gradient, and the observed Ca/Mg and Si/Al ratios in solution

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

Directory of Open Access Journals (Sweden)

Saad Younes Ghoubachi

2017-01-01

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

Transboundary geophysical mapping of geological elements and salinity distribution critical for the assessment of future sea water intrusion in response to sea level rise

DEFF Research Database (Denmark)

Joergensen, F.; Scheer, W.; Thomsen, S.

2012-01-01

Geophysical techniques are increasingly being used as tools for characterising the subsurface, and they are generally required to develop subsurface models that properly delineate the distribution of aquifers and aquitards, salt/freshwater interfaces, and geological structures that affect......, and sand aquifers are all examples of geological structures mapped by the geophysical data that control groundwater flow and to some extent hydrochemistry. Additionally, the data provide an excellent picture of the salinity distribution in the area and thus provide important information on the salt...... revealed. The mapped salinity distribution indicates preferential flow paths through and along specific geological structures within the area. The effects of a future sea level rise on the groundwater system and groundwater chemistry are discussed with special emphasis on the importance of knowing...

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

What lies beneath: Rural landholder interpretation of the risks of aquifer exploitation in Australia

Science.gov (United States)

Mendham, Emily; Curtis, Allan

2014-04-01

Risks associated with the management of groundwater in farming landscapes are at the forefront of public discourse in Australia and North America. There has been very little social research examining rural landholder attitudes to groundwater use and management. This is an important gap given the critical role social acceptability plays in resource access decisions, the important role groundwater plays in sustaining livelihoods, and the vital role it plays in maintaining groundwater dependent ecosystems. This paper attempts to address that gap by exploring how rural landholders interpret risks associated with groundwater use for irrigated agriculture. We do that by using a case study from south eastern Australia where farmers' livelihoods are increasingly dependent on groundwater. We draw upon spatially referenced survey data to investigate the general extent and nature of concern about risk associated with pumping groundwater. We also explore the factors influencing risk interpretation, including occupational identity and proximity to the aquifer. Survey results suggest that while there is concern about pumping groundwater for irrigated agriculture in the Wimmera region, there is also considerable confidence that negative outcomes can be avoided. The dimension of risk of most concern to respondents was the possibility that the benefits of pumping groundwater would not be shared equitably. Those reporting lower concern about the risks of groundwater pumping were more likely to own properties located above the aquifer, to exhibit a strong business orientation including prioritising economic values compared to environmental values, and to express attitudes indicating they thought private property rights should be protected. A substantial proportion of survey respondents indicated they were 'Unsure' on all the risk items in the survey. It seems the future social acceptability of groundwater exploitation in the Wimmera region will depend on the extent that those 'Unsure

Changes in hydrology and salinity accompanying a century of agricultural conversion in Argentina.

Science.gov (United States)

Jayawickreme, Dushmantha H; Santoni, Celina S; Kim, John H; Jobbágy, Esteban G; Jackson, Robert B

2011-10-01

Conversions of natural woodlands to agriculture can alter the hydrologic balance, aquifer recharge, and salinity of soils and groundwater in ways that influence productivity and sustainable land use. Using a land-use change chronosequence in semiarid woodlands of Argentina's Espinal province, we examined the distribution of moisture and solutes and estimated recharge rates on adjacent plots of native woodlands and rain-fed agriculture converted 6-90 years previously. Soil coring and geoelectrical profiling confirmed the presence of spatially extensive salt accumulations in dry woodlands and pervasive salt losses in areas converted to agriculture. A 1.1-km-long electrical resistivity transect traversing woodland, 70-year-old agriculture, and woodland, for instance, revealed a low-resistivity (high-salinity) horizon between approximately 3 m and 13 m depth in the woodlands that was virtually absent in the agricultural site because of leaching. Nine-meter-deep soil profiles indicated a 53% increase in soil water storage after 30 or more years of cultivation. Conservative groundwater-recharge estimates based on chloride tracer methods in agricultural plots ranged from approximately 12 to 45 mm/yr, a substantial increase from the led to >95% loss of sulfate and chloride ions from the shallow vadose zone in most agriculture plots. These losses correspond to over 100 Mg of sulfate and chloride salts potentially released to the region's groundwater aquifers through time with each hectare of deforestation, including a capacity to increase groundwater salinity to >4000 mg/L from these ions alone. Similarities between our findings and those of the dryland salinity problems of deforested woodlands in Australia suggest an important warning about the potential ecohydrological risks brought by the current wave of deforestation in the Espinal and other regions of South America and the world.

The Slow Moving Threat of Groundwater Salinization: Mechanisms, Costs, and Adaptation Strategies

Science.gov (United States)

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

2016-12-01

Population growth, the Green Revolution, and climate uncertainties have accelerated overdraft in groundwater basins worldwide, which in some regions is converting these basins into closed hydrologic systems, where the dominant exits for water are evapotranspiration and pumping. Irrigated agricultural basins are particularly at risk to groundwater salinization, as naturally occurring (i.e., sodium, potassium, chloride) and anthropogenic (i.e., nitrate fertilizers) salts leach back into the water table through the root zone, while a large portion of pumped groundwater leaves the system as it is evapotranspired by crops. Decreasing water quality associated with increases in Total Dissolved Solids (TDS) has been documented in aquifers across the United States in the past half century. This study suggests that the increase in TDS in aquifers can be partially explained by closed basin hydrogeology and rock-water interactions leading to groundwater salinization. This study will present: (1) a report on historical water quality in the Tulare basin, (2) a forward simulation of salt balance in Tulare Basin based on the Department of Water Resources numerical model C2VSim, and a simple mixing model, (3) an economic analysis forecasting the cost of desalination under varying degrees of managed groundwater recharge where the basin is gradually filled, avoiding hydraulic closure.

Potential environmental issues of CO2 storage in deep saline aquifers: Geochemical results from the Frio-I Brine Pilot test, Texas, USA

Science.gov (United States)

Kharaka, Yousif K.; Thordsen, James J.; Hovorka, Susan D.; Nance, H. Seay; Cole, David R.; Phelps, Tommy J.; Knauss, Kevin G.

2009-01-01

Sedimentary basins in general, and deep saline aquifers in particular, are being investigated as possible repositories for large volumes of anthropogenic CO2 that must be sequestered to mitigate global warming and related climate changes. To investigate the potential for the long-term storage of CO2 in such aquifers, 1600 t of CO2 were injected at 1500 m depth into a 24-m-thick "C" sandstone unit of the Frio Formation, a regional aquifer in the US Gulf Coast. Fluid samples obtained before CO2 injection from the injection well and an observation well 30 m updip showed a Na–Ca–Cl type brine with ∼93,000 mg/L TDS at saturation with CH4 at reservoir conditions; gas analyses showed that CH4 comprised ∼95% of dissolved gas, but CO2 was low at 0.3%. Following CO2 breakthrough, 51 h after injection, samples showed sharp drops in pH (6.5–5.7), pronounced increases in alkalinity (100–3000 mg/L as HCO3) and in Fe (30–1100 mg/L), a slug of very high DOC values, and significant shifts in the isotopic compositions of H2O, DIC, and CH4. These data, coupled with geochemical modeling, indicate corrosion of pipe and well casing as well as rapid dissolution of minerals, especially calcite and iron oxyhydroxides, both caused by lowered pH (initially ∼3.0 at subsurface conditions) of the brine in contact with supercritical CO2.These geochemical parameters, together with perfluorocarbon tracer gases (PFTs), were used to monitor migration of the injected CO2 into the overlying Frio “B”, composed of a 4-m-thick sandstone and separated from the “C” by ∼15 m of shale and siltstone beds. Results obtained from the Frio “B” 6 months after injection gave chemical and isotopic markers that show significant CO2 (2.9% compared with 0.3% CO2 in dissolved gas) migration into the “B” sandstone. Results of samples collected 15 months after injection, however, are ambiguous, and can be interpreted to show no additional injected CO2 in the “B” sandstone

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.

Effects of Land-Use Change and Managed Aquifer Recharge on Geochemical Reactions with Implications for Groundwater Quantity and Quality in Atoll Island Aquifers, Roi-Namur, Republic of the Marshall Islands

Science.gov (United States)

Hejazian, M.; Swarzenski, P. W.; Gurdak, J. J.; Odigie, K. O.; Storlazzi, C. D.

2015-12-01

This study compares the hydrogeochemistry of two contrasting atoll groundwater systems in Roi-Namur, Republic of the Marshall Islands. Roi-Namur houses a U.S. Department of Defense military installation and presents an ideal study location where a human impacted aquifer is co-located next to a natural aquifer as part of two artificially conjoined atoll islands. The hydrogeology and geochemistry of carbonate atoll aquifers has been well studied, particularly because of its small, well-defined hydrologic system that allows for relatively precise modeling. However, it is unknown how changes in land-use/land cover and managed aquifer recharge (MAR) alters natural geochemical processes in atoll aquifers. A better understanding of this has implications on groundwater quantity and quality, carbonate dissolution, and best aquifer management practices in the context of rising sea level and saltwater intrusion. Roi has been heavily modified to house military and civilian operations; here, lack of vegetation and managed recharge has increased the volume of potable groundwater and affected the geochemical processes in the freshwater lens and saltwater transition zone. Namur is heavily vegetated and the hydrogeology is indicative of a natural atoll island. A suite of monitoring wells were sampled across both island settings for major ions, nutrients, trace elements, DOC/DIC, δ13C and δ18O/2H isotopes. By modeling geochemical reactions using a conservative mixing approach, we measure deviations from expected reactions and compare the two contrasting settings using derived geochemical profiles through a wide salinity spectrum. Results indicate that groundwater on Namur is more heavily depleted in δ13C and has greater dissolved inorganic carbon, suggesting higher microbial oxidation and greater dissolution within the carbonate aquifer. This suggests MAR and reduction of vegetation makes the groundwater supply on atoll islands more resilient to sea level rise.

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

Optical tool for salinity detection by remote sensing spectroscopy: application on Oran watershed, Algeria

Science.gov (United States)

Abdellatif, Dehni; Mourad, Lounis

2017-07-01

Soil salinity is a complex problem that affects groundwater aquifers and agricultural lands in the semiarid regions. Remote sensing and spectroscopy database systems provide accuracy for salinity autodetection and dynamical delineation. Salinity detection techniques using polychromatic wavebands by field geocomputation and experimental data are time consuming and expensive. This paper presents an automated spectral detection and identification of salt minerals using a monochromatic waveband concept from multispectral bands-Landsat 8 Operational Land Imager (OLI) and Thermal InfraRed Sensor (TIRS) and spectroscopy United States Geological Survey database. For detecting mineral salts related to electrolytes, such as electronical and vibrational transitions, an integrated approach of salinity detection related to the optical monochromatic concept has been addressed. The purpose of this paper is to discriminate waveband intrinsic spectral similarity using the Beer-Lambert and Van 't Hoff laws for spectral curve extraction such as transmittance, reflectance, absorbance, land surface temperature, molar concentration, and osmotic pressure. These parameters are primordial for hydrodynamic salinity modeling and continuity identification using chemical and physical approaches. The established regression fitted models have been addressed for salt spectroscopy validation for suitable calibration and validation. Furthermore, our analytical tool is conducted for better decision interface using spectral salinity detection and identification in the Oran watershed, Algeria.

Saltwater Upconing and Decay Beneath a Well Pumping Above an Interface Zone

Energy Technology Data Exchange (ETDEWEB)

Zhou, Quanlin; Bear, Jacob; Bensabat, Jacob

2004-04-20

Saltwater, or brine, underlies fresh water in many aquifers, with a transition zone separating them. Pumping fresh water by wells located above the transition zone produces upconing of the latter, eventually salinizing the pumped water, forcing shut-off. The salinity of the pumped water depends on the pumping rate, on the location of the well's screen, on the fresh water flow regime, and on the difference in density between fresh and salt water, expressed as a dimensionless factor called density difference factor (DDF). Following the well's shut-off, the upconed saltwater mound undergoes decay, tending to return to the pre-pumping regime. In this paper, the upconing-decay processes in an axially symmetrical system are investigated to discover how they are affected by the DDF and by the dispersivities. The code FEAS-Brine, developed for the simulation of coupled density-dependent flow and salt transport, is used. In this code, the flow equation is solved by the Galer:wqkin finite element method (FEM), while the advective-dispersive salt transport equation is solved in the Eulerian-Lagrangian framework. This code does not suffer from the instability constraint on the Peclet number in the vicinity of the pumping well, where advection dominates the salt transport. Simulation results show that upconing is very sensitive to the DDF, which, in our work, is in the range from 0 (for ideal tracer) to 0.2 (for brine). It is shown that for the DDF of 0.025 (for seawater), local upconing occurs only for low iso-salinity surfaces, while those of high salt concentration, practically, do not shift toward the pumping well. For an ideal tracer, all iso-salinity surfaces rise toward the pumping well. For brine, however, only iso-salinity surfaces of very low salinity upcone towards the pumping well. The decay process is lengthy; it takes a long time for the upconed saltwater to migrate back to the original horizontal transition zone prior to pumping. However, the wider

Geochemistry and origins of mineralized waters in the Floridan aquifer system, northeastern Florida

Science.gov (United States)

Phelps, G.G.

2001-01-01

Increases in chloride concentration have been observed in water from numerous wells tapping the Floridan aquifer system in northeastern Florida. Although most increases have been in the eastern part of Duval County, Florida, no spatial pattern in elevated chloride concentrations is discernible. Possible sources of the mineralized water include modern seawater intrusion; unflushed Miocene-to-Pleistocene-age seawater or connate water in aquifer sediments; or mineralized water from deeper zones of the aquifer system or from formations beneath the Floridan aquifer system. The purpose of this study was to document the chemical and isotopic characteristics of water samples from various aquifer zones, and from geochemical and hydrogeologic data, to infer the source of the increased mineralization. Water samples were collected from 53 wells in northeastern Florida during 1997-1999. Wells tapped various zones of the aquifer including: the Fernandina permeable zone (FPZ), the upper zone of the Lower Floridan aquifer (UZLF), the Upper Floridan aquifer (UFA), and both the UFA and the UZLF. Water samples were analyzed for major ions and trace constituents and for isotopes of carbon, oxygen, hydrogen, sulfur, strontium, chlorine, and boron. Samples of rock from the aquifer were analyzed for isotopes of oxygen, carbon, and strontium. In general, water from various aquifer zones cannot be differentiated based on chemistry, except for water from FPZ wells. Major-ion concentrations vary as much within the upper zone of the Lower Floridan aquifer and the Upper Floridan aquifer as between these two zones. Simple models of mixing between fresh ground water and either modern seawater or water from the FPZ as a mineralized end member show that many water samples from the UZLF aquifer and the UFA are enriched in bicarbonate, calcium, magnesium, sulfate, fluoride, and silica and are depleted in sodium and potassium (as compared to concentrations predicted by simple mixing). Chemical mass

Geochemical and isotopic determination of deep groundwater contributions and salinity to the shallow groundwater and surface water systems, Mesilla Basin, New Mexico, Texas, and Mexico

Science.gov (United States)

Robertson, A.; Carroll, K. C.; Kubicki, C.; Purtshert, R.

2017-12-01

The Mesilla Basin/Conejos-Médanos aquifer system, extending from southern New Mexico to Chihuahua, Mexico, is a priority transboundary aquifer under the 2006 United States­-Mexico Transboundary Aquifer Assessment Act. Declining water levels, deteriorating water quality, and increasing groundwater use by municipal, industrial, and agricultural users on both sides of the international border raise concerns about long-term aquifer sustainability. Relative contributions of present-day and "paleo" recharge to sustainable fresh groundwater yields has not been determined and evidence suggests that a large source of salinity at the distal end of the Mesilla Basin is saline discharge from deep groundwater flow. The magnitude and distribution of those deep saline flow paths are not determined. The contribution of deep groundwater to discharge and salinity in the shallow groundwater and surface water of the Mesilla Basin will be determined by collecting discrete groundwater samples and analyzing for aqueous geochemical and isotopic tracers, as well as the radioisotopes of argon and krypton. Analytes include major ions, trace elements, the stable isotopes of water, strontium and boron isotopes, uranium isotopes, the carbon isotopes of dissolved inorganic carbon, noble gas concentrations and helium isotope ratios. Dissolved gases are extracted and captured from groundwater wells using membrane contactors in a process known as ultra-trace sampling. Gas samples are analyzed for radioisotope ratios of krypton by the ATTA method and argon by low-level counting. Effectiveness of the ultra-trace sampling device and method was evaluated by comparing results of tritium concentrations to the krypton-85 content. Good agreement between the analyses, especially in samples with undetectable tritium, indicates that the ultra-trace procedure is effective and confirms that introduction of atmospheric air has not occurred. The geochemistry data indicate a complex system of geochemical

Integrated assessment of future potential global change scenarios and their hydrological impacts in coastal aquifers – a new tool to analyse management alternatives in the Plana Oropesa-Torreblanca aquifer

Directory of Open Access Journals (Sweden)

D. Pulido-Velazquez

2018-05-01

improving our knowledge about the aquifer, and so comprises a tool to design sustainable adaptation management strategies taking into account the uncertainty in future GC conditions and their impacts. The results show that GC scenarios produce significant increases in the variability of flow budget components and in the salinity.

Analysis of data from test-well sites along the downdip limit of freshwater in the Edwards Aquifer, San Antonio, Texas, 1985-87

Science.gov (United States)

Groschen, G.E.

1994-01-01

Many researchers have studied the downdip limit of freshwater in the Edwards aquifer or various aspects of the saline-water zone and its relation to the freshwater zone. These studies were summarized and used to synthesize a consistent hydrologic and geochemical framework from which to interpret data from field studies. The concept derived from the previous work on the downdip limit of the freshwater zone is that fresh recharge water entered the aquifer and developed a vast flow system controlled by barrier faults. Some recharge water flows into the saline-water zone rather than toward major freshwater discharge points. The water that enters the salinewater zone continues to dissolve gypsum and dolomite, and calcite precipitates out of the water. This process of dedolomitization has helped to develop the large secondary porosity of the freshwater zone as the downdip limit of the freshwater zone progressively moved downdip in recent geologic time.

Identification of saline water intrusion in part of Cauvery deltaic region, Tamil Nadu, Southern India: using GIS and VES methods

Science.gov (United States)

Gnanachandrasamy, G.; Ramkumar, T.; Venkatramanan, S.; Chung, S. Y.; Vasudevan, S.

2016-06-01

We use electrical resistivity data arrayed in a 2715 km2 region with 30 locations to identify the saline water intrusion zone in part of Cauvery deltaic region, offshore Eastern India. From this dataset we are able to derive information on groundwater quality, thickness of aquifer zone, structural and stratigraphic conditions relevant to groundwater conditions, and permeability of aquifer systems. A total of 30 vertical electrode soundings (VES) were carried out by Schlumberger electrode arrangement to indicate complete lithology of this region using curve matching techniques. The electrical soundings exhibited that H and HK type curves were suitable for 16 shallow locations, and QH, KQ, K, KH, QQ, and HA curves were fit for other location. Low resistivity values suggested that saline water intrusion occurred in this region. According to final GIS map, most of the region was severely affected by seawater intrusion due to the use of over-exploitation of groundwater.The deteriorated groundwater resources in this coastal region should raise environmental and health concerns.

Digital surfaces and thicknesses of selected hydrogeologic units of the Floridan aquifer system in Florida and parts of Georgia, Alabama, and South Carolina

Science.gov (United States)

Williams, Lester J.; Dixon, Joann F.

2015-01-01

Digital surfaces and thicknesses of selected hydrogeologic units of the Floridan aquifer system were developed to define an updated hydrogeologic framework as part of the U.S. Geological Survey Groundwater Resources Program. The dataset contains structural surfaces depicting the top and base of the aquifer system, its major and minor hydrogeologic units and zones, geophysical marker horizons, and the altitude of the 10,000-milligram-per-liter total dissolved solids boundary that defines the approximate fresh and saline parts of the aquifer system. The thicknesses of selected major and minor units or zones were determined by interpolating points of known thickness or from raster surface subtraction of the structural surfaces. Additional data contained include clipping polygons; regional polygon features that represent geologic or hydrogeologic aspects of the aquifers and the minor units or zones; data points used in the interpolation; and polygon and line features that represent faults, boundaries, and other features in the aquifer system.

Challenge of urban sewage disposal in a karst region: Mérida, Yucátan, Mexico

Science.gov (United States)

Perry, E. C.; Villasuso, M.

2013-05-01

Four hydrogeologic factors influence urban sewage management on the northern Yucátan (Mexico) Peninsula: 1) lack of rivers capable of transporting and/or oxidizing sewage, 2) near-surface flat-lying, porous, permeable limestone and dolomite with shallow layers of variable permeability but without major subsurface aquitards, 3) rapid groundwater transmission, penetration of seawater inland beneath a fresh water lens, and a flat water table only a few meters below land surface and controlled by sea level, 4) near absence of soil cover. Mérida, Yucátan (population approaching one million, approximately the world's 450th most populous city) has no central sewage system. The water table beneath the city is consistently only 7-9 m below land surface, and the 40 m-thick fresh water lens, which is the sole source of municipal, industrial, and agricultural water, directly overlies a marine intrusion of modified seawater composition. The old city has an estimated 130,000 drains feeding untreated household waste directly into the permeable karst aquifer. Numerous storm drains send street runoff directly to the aquifer. In addition, industries, hotels, and some subdivisions have unmonitored injection wells that pump untreated wastewater into the underlying saline intrusion. Some injection wells have flow problems possibly because of low aquifer permeability within the saline intrusion. Deep injection is also problematic because density contrast with saline intrusion water can produce a gravity imbalance, and high sulfate water can react with organic waste to produce H2S. Some city water supply wells are reportedly affected by inflation of the water table beneath the city, by local upconing of saline water, and by nitrate contamination. Paradoxically, Mérida with an abundant, easily contaminated source of fresh water, lacks streams to transport sewage off-site, and thus shares some water supply/sewage treatment problems with cities in arid regions. Recently, compact

Evaluation of effects of changes in canal management and precipitation patterns on salinity in Biscayne Bay, Florida, using an integrated surface-water/groundwater model

Science.gov (United States)

Lohmann, Melinda A.; Swain, Eric D.; Wang, John D.; Dixon, Joann

2012-01-01

Biscayne National Park, located in Biscayne Bay in southeast Florida, is one of the largest marine parks in the country and sustains a large natural marine fishery where numerous threatened and endangered species reproduce. In recent years, the bay has experienced hypersaline conditions (salinity greater than 35 practical salinity units) of increasing magnitude and duration. Hypersalinity events were particularly pronounced during April to August 2004 in nearshore areas along the southern and middle parts of the bay. Prolonged hypersaline conditions can cause degradation of water quality and permanent damage to, or loss of, brackish nursery habitats for multiple species of fish and crustaceans as well as damage to certain types of seagrasses that are not tolerant of extreme changes in salinity. To evaluate the factors that contribute to hypersalinity events and to test the effects of possible changes in precipitation patterns and canal flows into Biscayne Bay on salinity in the bay, the U.S. Geological Survey constructed a coupled surface-water/groundwater numerical flow model. The model is designed to account for freshwater flows into Biscayne Bay through the canal system, leakage of salty bay water into the underlying Biscayne aquifer, discharge of fresh and salty groundwater from the Biscayne aquifer into the bay, direct effects of precipitation on bay salinity, indirect effects of precipitation on recharge to the Biscayne aquifer, direct effects of evapotranspiration (ET) on bay salinity, indirect effects of ET on recharge to the Biscayne aquifer, and maintenance of mass balance of both water and solute. The model was constructed using the Flow and Transport in a Linked Overland/Aquifer Density Dependent System (FTLOADDS) simulator, version 3.3, which couples the two-dimensional, surface-water flow and solute-transport simulator SWIFT2D with the density-dependent, groundwater flow an solute-transport simulator SEAWAT. The model was calibrated by a trial

Aquifer Characterization from Surface Geo-electrical Method, western coast of Maharashtra, India

Science.gov (United States)

DAS, A.; Maiti, D. S.

2017-12-01

Knowledge of aquifer parameters are necessary for managing groundwater amenity. These parameters are evaluated through pumping tests bring off from bore wells. But it is quite expensive as well as time consuming to carry out pumping tests at various sites and sometimes it is difficult to find bore hole at every required site. Therefore, an alternate method is put forward in which the aquifer parameters are evaluated from surface geophysical method. In this method, vertical electrical sounding (VES) with Schlumberger configuration were accomplished in 85 stations over Sindhudurg district. Sindhudurg district is located in the Konkan region of Maharashtra state, India. The district is located between north latitude 15°37' and 16° 40' and east longitude 73° 19' and 74° 13'. The area is having hard rock and acute groundwater problem. In this configuration, we have taken the maximum current electrode spacing of 200 m for every vertical electrical sounding (VES). Geo-electrical sounding data (true resistivity and thickness) is interpreted through resistivity inversion approach. The required parameters are achieved through resistivity inversion technique from which the aquifer variables (D-Z parameters, mean resistivity, hydraulic conductivity, transmissivity, and coefficient of anisotropy) are calculated by using some empirical formulae. Cross-correlation investigation has been done between these parameters, which eventually used to characterize the aquifer over the study area. At the end, the contour plot for these aquifer parameters has been raised which reveals the detailed distribution of aquifer parameters throughout the study area. From contour plot, high values of longitudinal conductance, hydraulic conductivity and transmissivity are demarcate over Kelus, Vengurle, Mochemar and Shiroda villages. This may be due to intrusion of saline water from Arabian sea. From contour trends, the aquifers are characterized from which the groundwater resources could be

Fingerprinting TCE in a bedrock aquifer using compound-specific isotope analysis.

Science.gov (United States)

Lojkasek-Lima, Paulo; Aravena, Ramon; Parker, Beth L; Cherry, John A

2012-01-01

A dual isotope approach based on compound-specific isotope analysis (CSIA) of carbon (C) and chlorine (Cl) was used to identify sources of persistent trichloroethylene (TCE) that caused the shut-down in 1994 of a municipal well in an extensive fractured dolostone aquifer beneath Guelph, Ontario. Several nearby industrial properties have known subsurface TCE contamination; however, only one has created a comprehensive monitoring network in the bedrock. The impacted municipal well and many monitoring wells were sampled for volatile organic compounds (VOCs), inorganic parameters, and CSIA. A wide range in isotope values was observed at the study site. The TCE varies between -35.6‰ and -21.8‰ and from 1.6‰ to 3.2‰ for δ(13) C and δ(37) Cl, respectively. In case of cis-1,2-dichloroethene, the isotope values range between -36.3‰ and -18.9‰ and from 2.4‰ to 4.7‰ for δ(13) C and δ(37) Cl, respectively. The dual isotope approach represented by a plot of δ(13) C vs. δ(37) Cl shows the municipal well samples grouped in a domain clearly separate from all other samples from the property with the comprehensive well network. The CSIA results collected under non-pumping and short-term pumping conditions thus indicate that this particular property, which has been studied intensively for several years, is not a substantial contributor of the TCE presently in the municipal well under non-pumping conditions. This case study demonstrates that CSIA signatures would have been useful much earlier in the quest to examine sources of the TCE in the municipal well if bedrock monitoring wells had been located at several depths beneath each of the potential TCE-contributing properties. Moreover, the CSIA results show that microbial reductive dechlorination of TCE occurs in some parts of the bedrock aquifer. At this site, the use of CSIA for C and Cl in combination with analyses of VOC and redox parameters proved to be important due to the complexity introduced by

Monitoring of heavy metal pollution of groundwater in a phreatic aquifer in Mersin-Turkey.

Science.gov (United States)

Demirel, Z

2007-09-01

In this study, heavy metal contents of groundwater from the Mersin aquifer were determined with photometric methods and used to determine the main factors controlling the pollution of groundwater in the area. Using MapInfo GIS software, spatial analysis and integration were carried out for mapping drinking water quality in the basin. From the photometric heavy metal analysis, it is inferred that the excess concentration of Fe, Ni, Mn, Mo and Cu at some locations is the cause of undesirable quality for drinking purposes. Similarly, the EC thematic map shows that considerable areas in the basin are having high salinity hazards. The reason for excess concentration of various heavy metals is the industrial activities and petroleum pipelines and salinity levels show the sea water intrusion.

Recharge beneath low-impact design rain gardens and the influence of El Niño Southern Oscillation on urban, coastal groundwater resources

Science.gov (United States)

Newcomer, M. E.; Gurdak, J. J.

2011-12-01

Groundwater resources in urban, coastal environments are highly vulnerable to increased human pressures and climate variability. Impervious surfaces, such as buildings, roads, and parking lots prevent infiltration, reduce recharge to underlying aquifers, and increase contaminants in surface runoff that often overflow sewage systems. To mitigate these effects, cities worldwide are adopting low impact design (LID) approaches that direct runoff into natural vegetated systems, such as rain gardens that reduce, filter, and slow stormwater runoff, and are hypothesized to increase infiltration and recharge rates to aquifers. The effects of LID on recharge rates and quality is unknown, particularly during intense precipitation events for cities along the Pacific coast in response to interannual variability of the El Niño Southern Oscillation (ENSO). Using vadose zone monitoring sensors and instruments, I collected and monitored soil, hydraulic, and geochemical data to quantify the rates and quality of infiltration and recharge to the California Coastal aquifer system beneath a LID rain garden and traditional turf-lawn setting in San Francisco, CA. The data were used to calibrate a HYDRUS-3D model to simulate recharge rates under historical and future variability of ENSO. Understanding these processes has important implications for managing groundwater resources in urban, coastal environments.

Salinity of deep groundwater in California: Water quantity, quality, and protection

Science.gov (United States)

Kang, Mary; Jackson, Robert B.

2016-01-01

Deep groundwater aquifers are poorly characterized but could yield important sources of water in California and elsewhere. Deep aquifers have been developed for oil and gas extraction, and this activity has created both valuable data and risks to groundwater quality. Assessing groundwater quantity and quality requires baseline data and a monitoring framework for evaluating impacts. We analyze 938 chemical, geological, and depth data points from 360 oil/gas fields across eight counties in California and depth data from 34,392 oil and gas wells. By expanding previous groundwater volume estimates from depths of 305 m to 3,000 m in California’s Central Valley, an important agricultural region with growing groundwater demands, fresh [groundwater volume is almost tripled to 2,700 km3, most of it found shallower than 1,000 m. The 3,000-m depth zone also provides 3,900 km3 of fresh and saline water, not previously estimated, that can be categorized as underground sources of drinking water (USDWs; freshwater zones and USDWs, respectively, in the eight counties. Deeper activities, such as wastewater injection, may also pose a potential threat to groundwater, especially USDWs. Our findings indicate that California’s Central Valley alone has close to three times the volume of fresh groundwater and four times the volume of USDWs than previous estimates suggest. Therefore, efforts to monitor and protect deeper, saline groundwater resources are needed in California and beyond. PMID:27354527

Modeling of CO2 storage in aquifers

International Nuclear Information System (INIS)

Savioli, Gabriela B; Santos, Juan E

2011-01-01

Storage of CO 2 in geological formations is a means of mitigating the greenhouse effect. Saline aquifers are a good alternative as storage sites due to their large volume and their common occurrence in nature. The first commercial CO 2 injection project is that of the Sleipner field in the Utsira Sand aquifer (North Sea). Nevertheless, very little was known about the effectiveness of CO 2 sequestration over very long periods of time. In this way, numerical modeling of CO 2 injection and seismic monitoring is an important tool to understand the behavior of CO 2 after injection and to make long term predictions in order to prevent CO 2 leaks from the storage into the atmosphere. The description of CO 2 injection into subsurface formations requires an accurate fluid-flow model. To simulate the simultaneous flow of brine and CO 2 we apply the Black-Oil formulation for two phase flow in porous media, which uses the PVT data as a simplified thermodynamic model. Seismic monitoring is modeled using Biot's equations of motion describing wave propagation in fluid-saturated poroviscoelastic solids. Numerical examples of CO 2 injection and time-lapse seismics using data of the Utsira formation show the capability of this methodology to monitor the migration and dispersal of CO 2 after injection.

Coastal Aquifer Contamination and Geochemical Processes Evaluation in Tugela Catchment, South Africa—Geochemical and Statistical Approaches

Directory of Open Access Journals (Sweden)

Badana Ntanganedzeni

2018-05-01

Full Text Available Assessment of groundwater quality, contamination sources and geochemical processes in the coastal aquifer of Tugela Catchment, South Africa were carried out by the geochemical and statistical approach using major ion chemistry of 36 groundwater samples. Results suggest that the spatial distribution pattern of EC, TDS, Na, Mg, Cl and SO4 are homogenous and elevated concentrations are observed in the wells in the coastal region and few wells near the Tugela River. Wells located far from the coast are enriched by Ca, HCO3 and CO3. Durov diagrams, Gibbs plots, ionic ratios, chloro alkaline indices (CAI1 and CAI2 and correlation analysis imply that groundwater chemistry in the coastal aquifer of Tugela Catchment is regulated by the ion exchange, mineral dissolution, saline sources, and wastewater infiltration from domestic sewage; septic tank leakage and irrigation return flow. Principle component analysis also ensured the role of saline and anthropogenic sources and carbonates dissolution on water chemistry. Spatial distributions of factor score also justify the above predictions. Groundwater suitability assessment indicates that around 80% and 90% of wells exceeded the drinking water standards recommended by the WHO and South African drinking water standards (SAWQG, respectively. Based on SAR, RSC, PI, and MH classifications, most of the wells are suitable for irrigation in the study region. USSL classification suggests that groundwater is suitable for coarse-textured soils and salt-tolerant crops. The study recommends that a proper management plan is required to protect this coastal aquifer efficiently.

What's Cooler Than Being Cool? Icefin: Robotic Exploration Beneath Antarctic Ice Shelves

Science.gov (United States)

Lawrence, J.; Schmidt, B. E.; Meister, M. R.; Glass, J. B.; Bowman, J. S.; Stockton, A. M.; Dichek, D.; Hurwitz, B.; Ramey, C.; Spears, A.; Walker, C. C.

2017-12-01

The 2017-18 Antarctic field season marks the first of three under the RISEUP project (Ross Ice Shelf & Europa Underwater Probe, NASA PSTAR program grant NNX16AL07G, PI B. E. Schmidt). RISEUP expands our efforts to understand the physical processes governing ice-ocean interactions from beneath the McMurdo Ice Shelf (MIS) to the Ross Ice Shelf (RIS), utilizing the modular autonomous or remotely operable submersible vehicle (AUV/ROV) Icefin. The remote, aphotic regions below Antarctic shelves present a unique opportunity- they are both poorly understood terrestrial environments and analogs for similar systems hypothesized to be present on other bodies in our solar system, such as Europa and Enceladus. By developing new robotic technologies to access and explore ice shelf cavities we are advancing our understanding of how temperature, pressure, and salinity influence the ice-ocean interface, the limits of habitable environments on Earth, and what biological processes and adaptations enable the life discovered by the RISP and WISSARD programs during initial exploration beneath the RIS. These investigations further our understanding of ocean world habitability and support planned and proposed planetary missions (e.g. Europa Clipper, Europa Lander) via improved constraint of marine ice accretion processes, organic entrainment, and interface habitability. Custom built at Georgia Tech and first deployed during the 2014/15 Antarctic season, Icefin is 3.5 m, 125 kg modular vehicle that now carries a full suite of oceanographic sensors (including conductivity, temperature, depth, dissolved O2, dissolved organic matter, turbidity, pH, eH, and sonar) that can be deployed through boreholes as small as 25 cm in diameter. Here we present continued analysis of basal ice and oceanographic observations in the McMurdo Sound region from 2012-2015 with, pending anticipated field work, comparisons to preliminary data from the 2017/18 field season beneath both the McMurdo and Ross Ice

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

CO2 point sources and subsurface storage capacities for CO2 in aquifers in Norway

International Nuclear Information System (INIS)

Boee, Reidulv; Magnus, Christian; Osmundsen, Per Terje; Rindstad, Bjoern Ivar

2002-01-01

The GESTCO project comprises a study of the distribution and coincidence of thermal CO 2 emission sources and location/quality of geological storage capacity in Europe. Four of the most promising types of geological storage are being studied. 1. Onshore/offshore saline aquifers with or without lateral seal. 2. Low entalpy geothermal reservoirs. 3. Deep methane-bearing coal beds and abandoned coal and salt mines. 4. Exhausted or near exhausted hydrocarbon structures. In this report we present an inventory of CO 2 point sources in Norway (1999) and the results of the work within Study Area C: Deep saline aquifers offshore/near shore Northern and Central Norway. Also offshore/near shore Southern Norway has been included while the Barents Sea is not described in any detail. The most detailed studies are on the Tilje and Aare Formations on the Troendelag Platform off Mid-Norway and on the Sognefjord, Fensfjord and Krossfjord Formations, southeast of the Troll Field off Western Norway. The Tilje Formation has been chosen as one of the cases to be studied in greater detail (numerical modelling) in the project. This report shows that offshore Norway, there are concentrations of large CO 2 point sources in the Haltenbanken, the Viking Graben/Tampen Spur area, the Southern Viking Graben and the central Trough, while onshore Norway there are concentrations of point sources in the Oslofjord/Porsgrund area, along the coast of western Norway and in the Troendelag. A number of aquifers with large theoretical CO 2 storage potential are pointed out in the North Sea, the Norwegian Sea and in the Southern Barents Sea. The storage capacity in the depth interval 0.8 - 4 km below sea level is estimated to be ca. 13 Gt (13000000000 tonnes) CO 2 in geological traps (outside hydrocarbon fields), while the storage capacity in aquifers not confined to traps is estimated to be at least 280 Gt CO 2 . (Author)

Adaptive surrogate model based multiobjective optimization for coastal aquifer management

Science.gov (United States)

Song, Jian; Yang, Yun; Wu, Jianfeng; Wu, Jichun; Sun, Xiaomin; Lin, Jin

2018-06-01

In this study, a novel surrogate model assisted multiobjective memetic algorithm (SMOMA) is developed for optimal pumping strategies of large-scale coastal groundwater problems. The proposed SMOMA integrates an efficient data-driven surrogate model with an improved non-dominated sorted genetic algorithm-II (NSGAII) that employs a local search operator to accelerate its convergence in optimization. The surrogate model based on Kernel Extreme Learning Machine (KELM) is developed and evaluated as an approximate simulator to generate the patterns of regional groundwater flow and salinity levels in coastal aquifers for reducing huge computational burden. The KELM model is adaptively trained during evolutionary search to satisfy desired fidelity level of surrogate so that it inhibits error accumulation of forecasting and results in correctly converging to true Pareto-optimal front. The proposed methodology is then applied to a large-scale coastal aquifer management in Baldwin County, Alabama. Objectives of minimizing the saltwater mass increase and maximizing the total pumping rate in the coastal aquifers are considered. The optimal solutions achieved by the proposed adaptive surrogate model are compared against those solutions obtained from one-shot surrogate model and original simulation model. The adaptive surrogate model does not only improve the prediction accuracy of Pareto-optimal solutions compared with those by the one-shot surrogate model, but also maintains the equivalent quality of Pareto-optimal solutions compared with those by NSGAII coupled with original simulation model, while retaining the advantage of surrogate models in reducing computational burden up to 94% of time-saving. This study shows that the proposed methodology is a computationally efficient and promising tool for multiobjective optimizations of coastal aquifer managements.

Long-Term Managed Aquifer Recharge in a Saline-Water Aquifer as a Critical Component of an Integrated Water Scheme in Southwestern Florida, USA

OpenAIRE

Thomas M. Missimer; Weixing Guo; John Woolschlager; Robert G. Maliva

2017-01-01

Managed Aquifer Recharge (MAR) systems can be used within the context of integrated water management to create solutions to multiple objectives. Southwestern Florida is faced with severe environmental problems associated with the wet season discharge of excessive quantities of surface water containing high concentrations of nutrients into the Caloosahatchee River Estuary and a future water supply shortage. A 150,000 m3/day MAR system is proposed as an economic solution to solve part of the en...

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.

Evaluation of potential gas clogging associated with managed aquifer recharge from a spreading basin, southwestern Utah, U.S.A.

Science.gov (United States)

Heilweil, Victor M.; Marston, Thomas

2013-01-01

Sand Hollow Reservoir in southwestern Utah, USA, is operated for both surface-water storage and managed aquifer recharge via infiltration from surface basin spreading to the underlying Navajo Sandstone. The total volume of estimated recharge from 2002 through 2011 was 131 Mm3., resulting in groundwater levels rising as much as 40 m. Hydraulic and hydrochemical data from the reservoir and various monitoring wells in Sand Hollow were used to evaluate the timing and location or reservoir recharge moving through the aquifer, along either potential clogging from trapped gases in pore throats, siltation, or algal mats. Several hyrdochemical tracers indicated this recharge had arrived at four monitoring wells located within about 300 m of the reservoir by 2012. At these wells, peak total dissolved-gas pressures exceeded two atmospheres (>1,500 mm mercury) and dissolved oxygen approached three times atmospherically equilibrated concentrations (>25 mg/L). these field parameters indicate that large amounts of gas trapped in pore spaces beneath the water table have dissolved. Lesser but notable increases in these dissolved-gas parameters (without increases in other indicators such as chloride-to-bromide ratios) at monitoring wells farther away (>300 m) indicate moderate amounts of in-situ sir entrapment and dissolution caused by the rise in regional groundwater levels. This is confirmed by hydrochemical difference between these sites and wells closer to the reservoir where recharge had already arrived. As the reservoir was being filled by 2002, managed aquifer recharge rates were initially very high (1.5 x 10-4 cm/s) with the vadose zone becoming saturated beneath and surrounding the reservoir. These rates declined to less than 3.5 x 10-6 cm/s during 2008. The 2002-08 decrease was likely associated with a declining regional hydraulic gradient and clogging. Increasing recharge rates during mid-2009 through 2010 may have been partly caused by dissolution of air bubbles

Development of a three-dimensional ground-water model of the Hanford Site unconfined aquifer system: FY 1995 status report

International Nuclear Information System (INIS)

Wurstner, S.K.; Thorne, P.D.; Chamness, M.A.; Freshley, M.D.; Williams, M.D.

1995-12-01

A three-dimensional numerical model of ground-water flow was developed for the uppermost unconfined aquifer at the Hanford Site in south-central Washington. Development of the model is supported by the Hanford Site Ground-Water Surveillance Project, managed by the Pacific Northwest National Laboratory, which is responsible for monitoring the sitewide movement of contaminants in ground water beneath the Hanford Site. Two objectives of the Ground-Water Surveillance Project are to (1) identify and quantify existing, emerging, or potential ground-water quality problems, and (2) assess the potential for contaminants to migrate from the Hanford Site through the ground-water pathway. Numerical models of the ground-water flow system are important tools for estimating future aquifer conditions and predicting the movement of contaminants through ground water. The Ground-Water Surveillance Project has supported development and maintenance of a two-dimensional model of the unconfined aquifer. This report describes upgrade of the two-dimensional model to a three-dimensional model. The numerical model is based on a three-dimensional conceptual model that will be continually refined and updated as additional information becomes available. This report presents a description of the three-dimensional conceptual model of ground-water flow in the unconfined aquifer system and then discusses the cur-rent state of the three-dimensional numerical model

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...

Final Report (BMWi Project No.: 02 E 10971): Joint project: Retention of radionuclides relevant for final disposal in natural clay rock and saline systems - Subproject 2: Geochemical behavior and transport of radionuclides in saline systems in the prese

Energy Technology Data Exchange (ETDEWEB)

Schmeide, Katja [Helmholtz-Zentrum Dresden, (Germany). Inst. of Resource Ecology; Fritsch, Katharina [Helmholtz-Zentrum Dresden, (Germany). Inst. of Resource Ecology; Lippold, Holger [Helmholtz-Zentrum Dresden, (Germany). Inst. of Resource Ecology; Poetsch, Maria [Helmholtz-Zentrum Dresden, (Germany). Inst. of Resource Ecology; Kulenkampff, Johannes [Helmholtz-Zentrum Dresden, (Germany). Inst. of Resource Ecology; Lippmann-Pipke, Johanna [Helmholtz-Zentrum Dresden, (Germany). Inst. of Resource Ecology; Jordan, Norbert [Helmholtz-Zentrum Dresden, (Germany). Inst. of Resource Ecology; Joseph, Claudia [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Helmholtz-Zentrum Dresden, (Germany). Inst. of Resource Ecology; Moll, Henry [Helmholtz-Zentrum Dresden, (Germany). Inst. of Resource Ecology; Cherkouk, Andrea [Helmholtz-Zentrum Dresden, (Germany). Inst. of Resource Ecology; Bader, Miriam [Helmholtz-Zentrum Dresden, (Germany). Inst. of Resource Ecology

2016-02-29

The objective of this project was to study the influence of increased salinities on interaction processes in the system radionuclide – organics – clay – aquifer. For this, complexation, redox, sorption, and diffusion studies were performed under variation of the ionic strength (up to 4 mol kg^-1) and the background electrolyte (NaCl, CaCl₂, MgCl₂).

Groundwater evolution beneath Hat Yai, a rapidly developing city in Thailand

Science.gov (United States)

Lawrence, A. R.; Gooddy, D. C.; Kanatharana, P.; Meesilp, W.; Ramnarong, V.

2000-09-01

Many cities and towns in South and Southeast Asia are unsewered, and urban wastewaters are often discharged either directly to the ground or to surface-water canals and channels. This practice can result in widespread contamination of the shallow groundwater. In Hat Yai, southern Thailand, seepage of urban wastewaters has produced substantial deterioration in the quality of the shallow groundwater directly beneath the city. For this reason, the majority of the potable water supply is obtained from groundwater in deeper semi-confined aquifers 30-50 m below the surface. However, downward leakage of shallow groundwater from beneath the city is a significant component of recharge to the deeper aquifer, which has long-term implications for water quality. Results from cored boreholes and shallow nested piezometers are presented. The combination of high organic content of the urban recharge and the shallow depth to the water table has produced strongly reducing conditions in the upper layer and the mobilisation of arsenic. A simple analytical model shows that time scales for downward leakage, from the surface through the upper aquitard to the semi-confined aquifer, are of the order of several decades. Résumé. De nombreuses villes du sud et du sud-est de l'Asie ne possèdent pas de réseaux d'égouts et les eaux usées domestiques s'écoulent souvent directement sur le sol ou dans des canaux et des cours d'eau de surface. Ces pratiques peuvent provoquer une contamination dispersée de la nappe phréatique. A Hat Yai (sud de la Thaïlande), les infiltrations d'eaux usées domestiques sont responsables d'une détérioration notable de la qualité de la nappe phréatique directement sous la ville. Pour cette raison, la majorité de l'eau potable est prélevée dans des aquifères semi-captifs plus profonds, situés entre 30 et 50 m sous la surface. Cependant, une drainance à partir de la nappe phréatique sous la ville constitue une composante significative de la recharge

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

Science.gov (United States)

Weyer, K. U.

2017-12-01

Coastal groundwater flow investigations at the Biscayne Bay, south of Miami, Florida, gave rise to the concept of density-driven flow of seawater into coastal aquifers creating a saltwater wedge. Within that wedge, convection-driven return flow of seawater and a dispersion zone were assumed by Cooper et al. (1964) to be the cause of the Biscayne aquifer `sea water wedge'. This conclusion was based on the chloride distribution within the aquifer and on an analytical model concept assuming convection flow within a confined aquifer without taking non-chemical field data into consideration. This concept was later labelled the `Henry Problem', which any numerical variable density flow program must be able to simulate to be considered acceptable. Both, `density-driven flow' and Tothian `groundwater flow systems' (with or without variable density conditions) are driven by gravitation. The difference between the two are the boundary conditions. 'Density-driven flow' occurs under hydrostatic boundary conditions while Tothian `groundwater flow systems' occur under hydrodynamic boundary conditions. Revisiting the Cooper et al. (1964) publication with its record of piezometric field data (heads) showed that the so-called sea water wedge has been caused by discharging deep saline groundwater driven by gravitational flow and not by denser sea water. Density driven flow of seawater into the aquifer was not found reflected in the head measurements for low and high tide conditions which had been taken contemporaneously with the chloride measurements. These head measurements had not been included in the flow interpretation. The very same head measurements indicated a clear dividing line between shallow local fresh groundwater flow and saline deep groundwater flow without the existence of a dispersion zone or a convection cell. The Biscayne situation emphasizes the need for any chemical interpretation of flow pattern to be supported by head data as energy indicators of flow fields

Marine water from mid-Holocene sea level highstand trapped in a coastal aquifer: Evidence from groundwater isotopes, and environmental significance

Energy Technology Data Exchange (ETDEWEB)

Lee, Stephen [School of Civil, Environmental and Chemical Engineering, RMIT University, Melbourne (Australia); Currell, Matthew, E-mail: Matthew.currell@rmit.edu.au [School of Civil, Environmental and Chemical Engineering, RMIT University, Melbourne (Australia); Cendón, Dioni I. [Australian Nuclear Science and Technology Organisation, Kirrawee (Australia); Connected Water Initiative, School of Biological, Earth and Environmental Sciences, University of New South Wales (UNSW), Sydney (Australia)

2016-02-15

A multi-layered coastal aquifer in southeast Australia was assessed using environmental isotopes, to identify the origins of salinity and its links to palaeo-environmental setting. Spatial distribution of groundwater salinity (electrical conductivity values ranging from 0.395 to 56.1 mS/cm) was examined along the coastline along with geological, isotopic and chemical data. This allowed assessment of different salinity sources and emplacement mechanisms. Molar chloride/bromide ratios range from 619 to 1070 (621 to 705 in samples with EC > 15 mS/cm), indicating salts are predominantly marine. Two distinct vertical salinity profiles were observed, one with increasing salinity with depth and another with saline shallow water overlying fresh groundwater. The saline shallow groundwater (EC = 45.4 to 55.7 mS/cm) has somewhat marine-like stable isotope ratios (δ{sup 18}O = − 2.4 to − 1.9 ‰) and radiocarbon activities indicative of middle Holocene emplacement (47.4 to 60.4 pMC). This overlies fresher groundwater with late Pleistocene radiocarbon ages and meteoric stable isotopes (δ{sup 18}O = − 5.5 to − 4.6‰). The configuration suggests surface inundation of the upper sediments by marine water during the mid-Holocene (c. 2–8 kyr BP), when sea level was 1–2 m above today's level. Profiles of chloride, stable isotopes, and radiocarbon indicate mixing between this pre-modern marine water and fresh meteoric groundwater to varying degrees around the coastline. Mixing calculations using chloride and stable isotopes show that in addition to fresh-marine water mixing, some salinity is derived from transpiration by halophytic vegetation (e.g. mangroves). The δ{sup 13}C ratios in saline water (− 17.6 to − 18.4‰) also have vegetation/organic matter signatures, consistent with emplacement by surface inundation and extensive interaction between vegetation and recharging groundwater. Saline shallow groundwater is preserved only in areas where low

Projections of on-farm salinity in coastal Bangladesh.

Science.gov (United States)

Clarke, D; Williams, S; Jahiruddin, M; Parks, K; Salehin, M

2015-06-01

This paper quantifies the expected impacts of climate change, climate variability and salinity accumulation on food production in coastal Bangladesh during the dry season. This forms part of a concerted series of actions on agriculture and salinity in Bangladesh under the UK funded Ecosystems for Poverty Alleviation programme and the British Council INSPIRE scheme. The work was undertaken by developing simulation models for soil water balances, dry season irrigation requirements and the effectiveness of the monsoon season rainfall at leaching accumulated salts. Simulations were run from 1981 to 2098 using historical climate data and a daily climate data set based on the Met Office Hadley Centre HadRM3P regional climate model. Results show that inter-seasonal and inter-annual variability are key factors that affect the viability of dry season vegetable crop growing. By the end of the 21(st) century the dry season is expected to be 2-3 weeks longer than now (2014). Monsoon rainfall amounts will remain the same or possibly slightly increase but it will occur over a slightly shorter wet season. Expectations of sea level rise and additional saline intrusion into groundwater aquifers mean that dry season irrigation water is likely to become more saline by the end of the 21(st) century. A study carried out at Barisal indicates that irrigating with water at up to 4 ppt can be sustainable. Once the dry season irrigation water quality goes above 5 ppt, the monsoon rainfall is no longer able to leach the dry season salt deposits so salt accumulation becomes significant and farm productivity will reduce by as a much as 50%, threatening the livelihoods of farmers in this region.

[Effect of shifting sand burial on evaporation reduction and salt restraint under saline water irrigation in extremely arid region].

Science.gov (United States)

Zhang, Jian-Guo; Zhao, Ying; Xu, Xin-Wen; Lei, Jia-Qiang; Li, Sheng-Yu; Wang, Yong-Dong

2014-05-01

The Taklimakan Desert Highway Shelterbelt is drip-irrigated with high saline groundwater (2.58-29.70 g x L(-1)), and shifting sand burial and water-salt stress are most common and serious problems in this region. So it is of great importance to study the effect of shifting sand burial on soil moisture evaporation, salt accumulation and their distribution for water saving, salinity restraint, and suitable utilization of local land and water resources. In this study, Micro-Lysimeters (MLS) were used to investigate dynamics of soil moisture and salt under different thicknesses of sand burial (1, 2, 3, 4, and 5 cm), and field control experiments of drip-irrigation were also carried out to investigate soil moisture and salt distribution under different thicknesses of shifting sand burial (5, 10, 15, 20, 25, 30, 35, and 40 cm). The soil daily and cumulative evaporation decreased with the increase of sand burial thickness in MLS, cumulative evaporation decreased by 2.5%-13.7% compared with control. And evaporative inhibiting efficiency increased with sand burial thickness, evaporative inhibiting efficiency of 1-5 cm sand burial was 16.7%-79.0%. Final soil moisture content beneath the interface of sand burial increased with sand burial thickness, and it increased by 2.5%-13.7% than control. The topsoil EC of shifting sand in MLS decreased by 1.19-6.00 mS x cm(-1) with the increasing sand burial thickness, whereas soil salt content beneath the interface in MLS increased and amplitude of the topsoil salt content was higher than that of the subsoil. Under drip-irrigation with saline groundwater, average soil moisture beneath the interface of shifting sand burial increased by 0.4% -2.0% compare with control, and the highest value of EC was 7.77 mS x cm(-1) when the sand burial thickness was 10 cm. The trend of salt accumulation content at shifting sand surface increased firstly, and then decreased with the increasing sand burial thickness. Soil salt contents beneath the

Unsafe Practice of Extracting Potable Water From Aquifers in the Southwestern Coastal Region of Bangladesh

Science.gov (United States)

Chowdhury, S. H.; Ahmed, A. U.; Iqbal, M. Z.

2009-05-01

The groundwater resource is of paramount importance to the lives and livelihoods of the millions of people in Bangladesh. Unfortunately, high levels of arsenic have been found in groundwater in many parts of Bangladesh. Besides, the salinity in water systems in the coastal areas has increased as a consequence of the flow diversion from the upper reaches of Ganges River by the neighboring country India. Since hand- pumped groundwater (tube) wells are the only viable sources of drinking water, maintaining drinking water security for over 6 million people in the south-west (SW) region has been a major challenge for the Bangladesh Government. Due to rapid exploitation of groundwater resources in excess of recharge capacity, non-saline water sources in the SW region have already been depleted and the hand tube wells have mostly been abandoned. Meanwhile, shrimp farming has resulted in saline water infiltration into the perched aquifer system in many areas. A recent survey covering123 wells out of 184, extending to a depth of 330 m, showed high salinity in water. Combined factors of rapid exploitation of shallow groundwater, depletion of the deep aquifers and the subsequent saline water intrusion into these aquifers have put long-term sustainability of the remaining fresh groundwater resource into jeopardy. Very high concentrations of nitrite are found in this study in many tube wells in the area where samples have been drawn from aquifer systems up to 244 m deep. Nitrite concentrations in 35 wells randomly sampled in this study range from 16.98 to 43.11 mg/L, averaging 27.55 mg/L. This is much higher than the Maximum Contaminant Level (MCL) of 1 mg/L set by the U.S. EPA for human consumption. Simultaneously, dissolved oxygen (DO) is found to be very low (0.1 to 2 mg/L). There are numerous reports and anecdotal evidences of "Blue Baby Syndrome" (methemoglobinemia) in the region, which is generally due to gradual suffocation caused by poor transport of oxygen from the

Using 81Kr-age of groundwater in the Guarani Aquifer, Brazil, to constrain estimates of continental degassing flux of 4He

Science.gov (United States)

Aggarwal, P. K.; Matsumoto, T.; Sturchio, N. C.; Chang, H. K.; Gastmans, D.; Lu, Z.; Jiang, W.; Müller, P.; Yokochi, R.; Han, L.; Klaus, P.; Torgersen, T.

2013-12-01

Continental degassing flux of helium is the dominant component of dissolved helium in deep groundwater together with that produced in-situ in the aquifer. A reliable estimate of the degassing flux is critical to the use of 4He as a dating tool in groundwater studies. The degassing flux is also important for understanding fluid and heat transport in the mantle and the rust. An independent tracer of groundwater age is required in order to deconvolute the two signals of the external, degassing flux and in situ production. Estimates of degassing flux mostly have relied upon shorter-lived radionuclides such as 14C and tritium and the resulting flux estimates have a significant variability (Torgersen, 2010). In the Guarani Aquifer in Brazil, an effective crustal 4He degassing flux into the aquifer was estimated from 81Kr ages ranging from about 70 Ka to 570 Ka. We then used the model framework of Toregesen and Ivey (1985), modified to include a diffusive reduction of originally uniform crustal helium flux from basement rocks through a thick sedimentary layer beneath the aquifer, to calculate a distribution of radiogenic 4He within the aquifer. With this framework, we obtain 4He ages that are consistent with ages based on 81Kr and 14C, and with a crustal degassing flux equivalent to that estimated from U and Th contents in the crust. The model framework for the Guarani Aquifer is also applied to data from other deep aquifers in Africa and Australia and our results suggest that the continental flux of 4He may be uniform, at least in stable continental areas. Additionally, a reliable estimate of the 4He degassing flux also helps to constrain the surficial discharge of deep groundwater.

Where is the hot rock and where is the ground water – Using CSAMT to map beneath and around Mount St. Helens

Science.gov (United States)

Wynn, Jeff; Mosbrucker, Adam; Pierce, Herbert; Spicer, Kurt R.

2016-01-01

We have observed several new features in recent controlled-source audio-frequency magnetotelluric (CSAMT) soundings on and around Mount St. Helens, Washington State, USA. We have identified the approximate location of a strong electrical conductor at the edges of and beneath the 2004–08 dome. We interpret this conductor to be hot brine at the hot-intrusive-cold-rock interface. This contact can be found within 50 meters of the receiver station on Spine 5, which extruded between April and July of 2005. We have also mapped separate regional and glacier-dome aquifers, which lie one atop the other, out to considerable distances from the volcano.

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

Vertically-Integrated Dual-Continuum Models for CO2 Injection in Fractured Aquifers

Science.gov (United States)

Tao, Y.; Guo, B.; Bandilla, K.; Celia, M. A.

2017-12-01

Injection of CO2 into a saline aquifer leads to a two-phase flow system, with supercritical CO2 and brine being the two fluid phases. Various modeling approaches, including fully three-dimensional (3D) models and vertical-equilibrium (VE) models, have been used to study the system. Almost all of that work has focused on unfractured formations. 3D models solve the governing equations in three dimensions and are applicable to generic geological formations. VE models assume rapid and complete buoyant segregation of the two fluid phases, resulting in vertical pressure equilibrium and allowing integration of the governing equations in the vertical dimension. This reduction in dimensionality makes VE models computationally more efficient, but the associated assumptions restrict the applicability of VE model to formations with moderate to high permeability. In this presentation, we extend the VE and 3D models for CO2 injection in fractured aquifers. This is done in the context of dual-continuum modeling, where the fractured formation is modeled as an overlap of two continuous domains, one representing the fractures and the other representing the rock matrix. Both domains are treated as porous media continua and can be modeled by either a VE or a 3D formulation. The transfer of fluid mass between rock matrix and fractures is represented by a mass transfer function connecting the two domains. We have developed a computational model that combines the VE and 3D models, where we use the VE model in the fractures, which typically have high permeability, and the 3D model in the less permeable rock matrix. A new mass transfer function is derived, which couples the VE and 3D models. The coupled VE-3D model can simulate CO2 injection and migration in fractured aquifers. Results from this model compare well with a full-3D model in which both the fractures and rock matrix are modeled with 3D models, with the hybrid VE-3D model having significantly reduced computational cost. In

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

Identifying and quantifying geochemical and mixing processes in the Matanza-Riachuelo Aquifer System, Argentina.

Science.gov (United States)

Armengol, S; Manzano, M; Bea, S A; Martínez, S

2017-12-01

The Matanza-Riachuelo River Basin, in the Northeast of the Buenos Aires Province, is one of the most industrialized and populated region in Argentina and it is worldwide known for its alarming environmental degradation. In order to prevent further damages, the aquifer system, which consists of two overlaid aquifers, is being monitored from 2008 by the river basin authority, Autoridad de la Cuenca Matanza-Riachuelo. The groundwater chemical baseline has been established in a previous paper (Zabala et al., 2016), and this one is devoted to the identification of the main physical and hydrogeochemical processes that control groundwater chemistry and its areal distribution. Thirty five representative groundwater samples from the Upper Aquifer and thirty four from the deep Puelche Aquifer have been studied with a multi-tool approach to understand the origin of their chemical and isotopic values. The resulting conceptual model has been validated though hydrogeochemical modeling. Most of the aquifer system has fresh groundwater, but some areas have brackish and salt groundwater. Water recharging the Upper Aquifer is of the Ca-HCO 3 type as a result of soil CO 2 and carbonate dissolution. Evapotranspiration plays a great role concentrating recharge water. After recharge, groundwater becomes Na-HCO 3 , mostly due to cation exchange with Na release and Ca uptake, which induces calcite dissolution. Saline groundwaters exist in the lower and upper sectors of the basin as a result of Na-HCO 3 water mixing with marine water of different origins. In the upper reaches, besides mixing with connate sea water other sources of SO 4 exist, most probably gypsum and/or sulfides. This work highlights the relevance of performing detailed studies to understand the processes controlling groundwater chemistry at regional scale. Moreover, it is a step forward in the knowledge of the aquifer system, and provides a sound scientific basis to design effective management programs and recovery plans

Preliminary survey of the vulnerability to the contamination of the aquifers of Morondava river catchments

International Nuclear Information System (INIS)

Randrianasolo, A.F.

2004-01-01

The objective of this work is to make a preliminary survey of the vulnerability to the contamination of the aquifers of Morondava river catchments. The methods used are the geological and hydrogeological surveys, the hydrochemistry and isotopic techniques. This survey allows us to have an overview of the chemical features of groundwaters, conditions of recharge, and especially to determine the potential and active zone of nitrate pollution. Two field works have been carried out within the frame of MAG/8/003 project. The first one is focused on groundwater sampling and surface water sampling, and the second one is based on the geological and hydrogeological surveys. The samples were sent for isotope ( 18 O, 2 H, 15 N, 87 Sr, 3 H) and chemical analysis to the I.A.E.A laboratories. The survey gave the following conclusions: the groundwaters are affected by evaporation before or during infiltration and saline intrusion. The region of Morondava is submitted to a regime of simple oceanic precipitation (excess in deuterium). The boreholes waters is of sodic-bicarbonate chemical type, whereas well waters belong to the calcic-bicarbonate. The superficial aquifers (subsurface water) trapped by the wells are more vulnerable than deep aquifers (homogeneous aquifers) trapped by boreholes. These hypotheses are proven by geological and hydrogeological investigations, by the groundwaters nitrate analyses results, and are confirmed by radioactive isotope. [fr

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.

Radium Adsorption to Iron Bearing Minerals in Variable Salinity Waters

Science.gov (United States)

Chen, M.; Kocar, B. D.

2014-12-01

Radium is a common, naturally occurring radioactive metal found in many subsurface environments. Radium isotopes are a product of natural uranium and thorium decay, and are particularly abundant within groundwaters where minimal flux leads to accumulation within porewaters. Radium has been used as a natural tracer to estimate submarine groundwater discharge (SGD) [1], where the ratios of various radium isotopes are used to estimate total groundwater flux to and from the ocean [2]. Further, it represents a substantial hazard in waste water produced after hydraulic fracturing for natural gas extraction [3], resulting in a significant risk of environmental release and increased cost for water treatment or disposal. Adsorption to mineral surfaces represents a primary pathway of radium retention within subsurface environments. For SGD studies, it is important to understand adsorption processes to correctly estimate GW fluxes, while in hydraulic fracturing, radium adsorption to aquifer solids will mediate the activities of radium within produced water. While some studies of radium adsorption to various minerals have been performed [4], there is a limited understanding of the surface chemistry of radium adsorption, particularly to iron-bearing minerals such as pyrite, goethite and ferrihydrite. Accordingly, we present the results of sorption experiments of radium to a suite of iron-bearing minerals representative of those found within deep saline and near-surface (freshwater) aquifers, and evaluate impacts of varying salinity solutions through the use of artificial groundwater, seawater, and shale formation brine. Further, we explore the impacts of pyrite oxidation and ferrihydrite transformation to other iron-bearing secondary minerals on the retention of radium. This work lays the groundwork for further study of radium use as a tracer for SGD, as well as understanding mechanisms of radium retention and release from deep aquifer materials following hydraulic fracturing

Electrical resistivity characterization of anisotropy in the Biscayne Aquifer.

Science.gov (United States)

Yeboah-Forson, Albert; Whitman, Dean

2014-01-01

Electrical anisotropy occurs when electric current flow varies with azimuth. In porous media, this may correspond to anisotropy in the hydraulic conductivity resulting from sedimentary fabric, fractures, or dissolution. In this study, a 28-electrode resistivity imaging system was used to investigate electrical anisotropy at 13 sites in the Biscayne Aquifer of SE Florida using the rotated square array method. The measured coefficient of electrical anisotropy generally ranged from 1.01 to 1.12 with values as high as 1.36 found at one site. The observed electrical anisotropy was used to estimate hydraulic anisotropy (ratio of maximum to minimum hydraulic conductivity) which ranged from 1.18 to 2.83. The largest values generally were located on the Atlantic Coastal Ridge while the lowest values were in low elevation areas on the margin of the Everglades to the west. The higher values of anisotropy found on the ridge may be due to increased dissolution rates of the oolitic facies of the Miami formation limestone compared with the bryozoan facies to the west. The predominate trend of minimum resistivity and maximum hydraulic conductivity was E-W/SE-NW beneath the ridge and E-W/SW-NE farther west. The anisotropy directions are similar to the predevelopment groundwater flow direction as indicated in published studies. This suggests that the observed anisotropy is related to the paleo-groundwater flow in the Biscayne Aquifer. © 2013, National Ground Water Association.

Application of a Density-Dependent Numerical Model (MODHMS) to Assess Salinity Intrusion in the Biscayne Aquifer, North Miami-Dade County, Florida

Science.gov (United States)

Guha, H.; Panday, S.

2005-05-01

Miami-Dade County is located at the Southeastern part of the State of Florida adjoining the Atlantic coast. The sole drinking water source is the Biscayne Aquifer, which is an unconfined freshwater aquifer, composed of marine limestone with intermediate sand lenses. The aquifer is highly conductive with hydraulic conductivity values ranging from 1,000 ft/day to over 100,000 ft/day in some areas. Saltwater intrusion from the coast is an immediate threat to the freshwater resources of the County. Therefore, a multilayer density-dependent transient groundwater model was developed to evaluate the saltwater intrusion characteristics of the system. The model was developed using MODHMS, a finite difference, fully coupled groundwater and surface water flow and transport model. The buoyancy term is included in the equation for unconfined flow and the flow and transport equations are coupled using an iterative scheme. The transport equation was solved using an adaptive implicit total variation diminishing (TVD) scheme and anisotropy of dispersivity was included for longitudinal, transverse, vertical transverse, and vertical longitudinal directions. The model eastern boundaries extended approximately 3.5 miles into the Atlantic Ocean while the western boundary extended approximately 27 miles inland from the coast. The northern and southern boundaries extend 6 miles into Broward County and up to the C-100 canal in Miami-Dade County respectively. Close to 2 million active nodes were simulated, with horizontal discretization of 500 feet. A total of nine different statistical analyses were conducted with observed and simulated hydraulic heads. The analysis indicates that the model simulated hydraulic heads matched closely with the observed heads across the model domain. In general, the model reasonably simulated the inland extent of saltwater intrusion within the aquifer, and matched relatively well with limited observed chloride data from monitoring wells along the coast

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.

Quantifying an aquifer nitrate budget and future nitrate discharge using field data from streambeds and well nests

Science.gov (United States)

Gilmore, Troy E.; Genereux, David P.; Solomon, D. Kip; Farrell, Kathleen M.; Mitasova, Helena

2016-11-01

Novel groundwater sampling (age, flux, and nitrate) carried out beneath a streambed and in wells was used to estimate (1) the current rate of change of nitrate storage, dSNO3/dt, in a contaminated unconfined aquifer, and (2) future [NO3-]FWM (the flow-weighted mean nitrate concentration in groundwater discharge) and fNO3 (the nitrate flux from aquifer to stream). Estimates of dSNO3/dt suggested that at the time of sampling (2013) the nitrate storage in the aquifer was decreasing at an annual rate (mean = -9 mmol/m2yr) equal to about one-tenth the rate of nitrate input by recharge. This is consistent with data showing a slow decrease in the [NO3-] of groundwater recharge in recent years. Regarding future [NO3-]FWM and fNO3, predictions based on well data show an immediate decrease that becomes more rapid after ˜5 years before leveling out in the early 2040s. Predictions based on streambed data generally show an increase in future [NO3-]FWM and fNO3 until the late 2020s, followed by a decrease before leveling out in the 2040s. Differences show the potential value of using information directly from the groundwater—surface water interface to quantify the future impact of groundwater nitrate on surface water quality. The choice of denitrification kinetics was similarly important; compared to zero-order kinetics, a first-order rate law levels out estimates of future [NO3-]FWM and fNO3 (lower peak, higher minimum) as legacy nitrate is flushed from the aquifer. Major fundamental questions about nonpoint-source aquifer contamination can be answered without a complex numerical model or long-term monitoring program.

Geochemical evidence for groundwater behavior in an unconfined aquifer, south Florida

Science.gov (United States)

Meyers, Jayson B.; Swart, Peter K.; Meyers', Janet L.

1993-07-01

Five well sites have been investigated along an east-west transect across the surfical aquifer system (SAS) of south Florida. Differences between rainfall during wet seasons (June-October) and evaporation during dry seasons (November-May) give surface waters of this region isotopically light ( δ 18O -22‰ and δ D -7.6‰ ) and heavy ( δ 18O +4.2‰ ) compositions, respectively. Surface waters and shallow groundwaters are enriched in 18O and D to the west, which is consistent with westward decrease in equal excess of rainfall. In the shallow portion of the SAS (less than 20 m, Biscayne sub-aquifer) heterogeneous stable isotopic compositions occur over short spans of time (less than 90 days), reflecting seasonal changes in the isotopic composition of recharge and rapid flushing. Homogeneous stable isotopic compositions occur below the Biscayne sub-aquifer, marking the zone of delayed circulation. Surface evaporation calculated from a stable isotope evaporation model agrees with previously published estimates of 75-95% by physical evaporation measurements and water budget calculations. This model contains many parameters that are assumed to be mean values, but short-term variability in some of these parameters may make this model unsuitable for the application of yearly mean values. For the Everglades, changes in the isotopic composition of atmospheric vapor during the dry season may cause the model to yield anomalous results when annual mean values are used. Chloride-enriched waters (more than 280 mg 1 -1) form a plume emanating from the bottom central portion of the transect. Elevated chloride concentration and light stable isotopic composition ( δ 18O ≈ -2‰ , δ D ≈ -8‰ ) suggest this plume is probably caused not by salinity of residual seawater in the aquifer, but by leakage from the minor artesian water-bearing zone of the Floridan aquifer system. Stable isotope values from Floridan aquifer groundwater plot close to the meteoric water line, in the

Microbial composition in a deep saline aquifer in the North German Basin -microbiologically induced corrosion and mineral precipitation affecting geothermal plant operation and the effects of plant downtime

Science.gov (United States)

Lerm, Stephanie; Westphal, Anke; Miethling-Graff, Rona; Alawi, Mashal; Seibt, Andrea; Wolfgramm, Markus; Würdemann, Hilke

2013-04-01

The microbial composition in fluids of a deep saline geothermal used aquifer in the North German Basin was characterized over a period of five years. The genetic fingerprinting techniques PCR-SSCP and PCR-DGGE revealed distinct microbial communities in fluids produced from the cold and warm side of the aquifer. Direct cell counting and quantification of 16S rRNA genes and dissimilatory sulfite reductase (dsrA) genes by real-time PCR proved different population sizes in fluids, showing higher abundance of Bacteria and sulfate reducing bacteria (SRB) in cold fluids compared to warm fluids. Predominating SRB in the cold well probably accounted for corrosion damage to the submersible well pump, and iron sulfide precipitates in the near wellbore area and topside facility filters. This corresponded to a lower sulfate content in fluids produced from the cold well as well as higher content of hydrogen gas that was probably released from corrosion, and maybe favoured growth of hydrogenotrophic SRB. Plant downtime significantly influenced the microbial biocenosis in fluids. Samples taken after plant restart gave indications about the processes occurring downhole during those phases. High DNA concentrations in fluids at the beginning of the restart process with a decreasing trend over time indicated a higher abundance of microbes during plant downtime compared to regular plant operation. It is likely that a gradual drop in temperature as well as stagnant conditions favoured the growth of microbes and maturation of biofilms at the casing and in pores of the reservoir rock in the near wellbore area. Furthermore, it became obvious that the microorganisms were more associated to particles then free-living. This study reflects the high influence of microbial populations for geothermal plant operation, because microbiologically induced precipitative and corrosive processes adversely affect plant reliability. Those processes may favourably occur during plant downtime due to enhanced

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

Geochemical detection of carbon dioxide in dilute aquifers

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Aines Roger

2009-03-01

Full Text Available Abstract Background Carbon storage in deep saline reservoirs has the potential to lower the amount of CO2 emitted to the atmosphere and to mitigate global warming. Leakage back to the atmosphere through abandoned wells and along faults would reduce the efficiency of carbon storage, possibly leading to health and ecological hazards at the ground surface, and possibly impacting water quality of near-surface dilute aquifers. We use static equilibrium and reactive transport simulations to test the hypothesis that perturbations in water chemistry associated with a CO2 gas leak into dilute groundwater are important measures for the potential release of CO2 to the atmosphere. Simulation parameters are constrained by groundwater chemistry, flow, and lithology from the High Plains aquifer. The High Plains aquifer is used to represent a typical sedimentary aquifer overlying a deep CO2 storage reservoir. Specifically, we address the relationships between CO2 flux, groundwater flow, detection time and distance. The CO2 flux ranges from 103 to 2 × 106 t/yr (0.63 to 1250 t/m2/yr to assess chemical perturbations resulting from relatively small leaks that may compromise long-term storage, water quality, and surface ecology, and larger leaks characteristic of short-term well failure. Results For the scenarios we studied, our simulations show pH and carbonate chemistry are good indicators for leakage of stored CO2 into an overlying aquifer because elevated CO2 yields a more acid pH than the ambient groundwater. CO2 leakage into a dilute groundwater creates a slightly acid plume that can be detected at some distance from the leak source due to groundwater flow and CO2 buoyancy. pH breakthrough curves demonstrate that CO2 leaks can be easily detected for CO2 flux ≥ 104 t/yr within a 15-month time period at a monitoring well screened within a permeable layer 500 m downstream from the vertical gas trace. At lower flux rates, the CO2 dissolves in the aqueous phase

Geochemical detection of carbon dioxide in dilute aquifers.

Science.gov (United States)

Carroll, Susan; Hao, Yue; Aines, Roger

2009-03-26

Carbon storage in deep saline reservoirs has the potential to lower the amount of CO2 emitted to the atmosphere and to mitigate global warming. Leakage back to the atmosphere through abandoned wells and along faults would reduce the efficiency of carbon storage, possibly leading to health and ecological hazards at the ground surface, and possibly impacting water quality of near-surface dilute aquifers. We use static equilibrium and reactive transport simulations to test the hypothesis that perturbations in water chemistry associated with a CO2 gas leak into dilute groundwater are important measures for the potential release of CO2 to the atmosphere. Simulation parameters are constrained by groundwater chemistry, flow, and lithology from the High Plains aquifer. The High Plains aquifer is used to represent a typical sedimentary aquifer overlying a deep CO2 storage reservoir. Specifically, we address the relationships between CO2 flux, groundwater flow, detection time and distance. The CO2 flux ranges from 10(3) to 2 x 10(6) t/yr (0.63 to 1250 t/m2/yr) to assess chemical perturbations resulting from relatively small leaks that may compromise long-term storage, water quality, and surface ecology, and larger leaks characteristic of short-term well failure. For the scenarios we studied, our simulations show pH and carbonate chemistry are good indicators for leakage of stored CO2 into an overlying aquifer because elevated CO2 yields a more acid pH than the ambient groundwater. CO2 leakage into a dilute groundwater creates a slightly acid plume that can be detected at some distance from the leak source due to groundwater flow and CO2 buoyancy. pH breakthrough curves demonstrate that CO2 leaks can be easily detected for CO2 flux >or= 10(4) t/yr within a 15-month time period at a monitoring well screened within a permeable layer 500 m downstream from the vertical gas trace. At lower flux rates, the CO2 dissolves in the aqueous phase in the lower most permeable unit and does

The fault pattern in the northern Negev and southern Coastal Plain of Israel and its hydrogeological implications for groundwater flow in the Judea Group aquifer

Science.gov (United States)

Weinberger, G.; Rosenthal, E.

1994-03-01

On the basis of a broadly expanding data base, the hydrogeological properties of the Judea Group sequence in the northern Negev and southern Coastal Plain of Israel have been reassessed. The updated subsurface model is based on data derived from water- and oil-wells and on recent large-scale geophysical investigations. A new regional pattern of the reassessed geological through the subsurface of the study area has been revealed. In view of the reassessed geological and hydrological subsurface setting, it appears that the Judea Group aquifer should not be regarded as one continuous and undisturbed hydrological unit; owing to the occurrence of regional faults, its subaquifers are locally interconnected. These subaquifers, which contain mainly high-quality water, are juxtaposed, as a result of faulting, against Kurnub Group sandstones containing brackish paleowater. The latter Group is faulted against late Jurassic formations containing highly saline groundwater. In the Beer Sheva area, the Judea Group aquifer is vertically displaced against the Senonian and Eocene Mt. Scopus and Avdat Groups, which also contain brackish and saline water. In the southern Coastal Plain, major faults locally dissect also the Pleistocene Kurkar Group, facilitating inflow of Mg-rich groundwater deriving from Judea Group dolomites. The new geological evidence and its hydrogeological implications provide new solutions for previously unexplained salinization phenomena.

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.

Hydrochemistry of the Guarani Aquifer System and implications for its management; Hidroquimica del Sistema Acuifero Guarani e implicaciones para la gestion

Energy Technology Data Exchange (ETDEWEB)

Manzano, M.; Guimaraens, M.

2012-11-01

Within the framework of the Project for the Sustainable Management of the Guarani aquifer system (GAS) we have studied the chemical baseline of its distribution and origin in order to build up a sound scientific understanding of the aquifer and thus be able to support its correct management. We have used chemical data obtained within this project and also in former studies. The baseline chemical facies, their distribution and the possible hydrogeochemical reactions involved were studied with the support of classical graphic tools. The hydrochemical conceptual model was checked with mass balances and inverse modeling, and the relative contribution to the balances of every thermodynamically feasible reaction was assessed. The GAS chemical baseline is quite homogeneous. Three chemical facies were found throughout the aquifer as a whole, appearing in the same order downstream from the outcropping recharge areas towards the confined sectors in the centre of the basin: facies A (Ca-HCO{sub 3} and Mg-HCO{sub 3} water), produced mainly by rainwater infiltration dissolving CO{sub 2} and carbonate minerals; facies B (Na-HCO{sub 3} water), caused mostly by facies A water undergoing cationic exchange and carbonate dissolution; and facies C (Na-HCO{sub 3}-SO{sub 4}-Cl to Na-Cl or Na-SO{sub 4} water), resulting from the mixing of facies B with a more saline groundwater from geological formations underlying those formally designed as being part of the SAG. Fluorine seems to be associated with this deep, saline groundwater. Under natural conditions the magnitude of the upward flows seems scarcely relevant, but uncontrolled groundwater exploitation may lead to increased flow rates and to the pollution of large aquifer areas that at the moment contain good-quality water. (Author)

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.

Assessment of managed aquifer recharge at Sand Hollow Reservoir, Washington County, Utah, updated to conditions through 2014

Science.gov (United States)

Marston, Thomas M.; Heilweil, Victor M.

2016-09-08

Sand Hollow Reservoir in Washington County, Utah, was completed in March 2002 and is operated primarily for managed aquifer recharge by the Washington County Water Conservancy District. From 2002 through 2014, diversions of about 216,000 acre-feet from the Virgin River to Sand Hollow Reservoir have allowed the reservoir to remain nearly full since 2006. Groundwater levels in monitoring wells near the reservoir rose through 2006 and have fluctuated more recently because of variations in reservoir stage and nearby pumping from production wells. Between 2004 and 2014, about 29,000 acre-feet of groundwater was withdrawn by these wells for municipal supply. In addition, about 31,000 acre-feet of shallow seepage was captured by French drains adjacent to the North and West Dams and used for municipal supply, irrigation, or returned to the reservoir. From 2002 through 2014, about 127,000 acre-feet of water seeped beneath the reservoir to recharge the underlying Navajo Sandstone aquifer.Water quality continued to be monitored at various wells in Sand Hollow during 2013–14 to evaluate the timing and location of reservoir recharge as it moved through the aquifer. Changing geochemical conditions at monitoring wells WD 4 and WD 12 indicate rising groundwater levels and mobilization of vadose-zone salts, which could be a precursor to the arrival of reservoir recharge.

Assessment of managed aquifer recharge from Sand Hollow Reservoir, Washington County, Utah, updated to conditions in 2010

Science.gov (United States)

Heilweil, Victor M.; Marston, Thomas M.

2011-01-01

Sand Hollow Reservoir in Washington County, Utah, was completed in March 2002 and is operated primarily for managed aquifer recharge by the Washington County Water Conservancy District. From 2002 through 2009, total surface-water diversions of about 154,000 acre-feet to Sand Hollow Reservoir have allowed it to remain nearly full since 2006. Groundwater levels in monitoring wells near the reservoir rose through 2006 and have fluctuated more recently because of variations in reservoir water-level altitude and nearby pumping from production wells. Between 2004 and 2009, a total of about 13,000 acre-feet of groundwater has been withdrawn by these wells for municipal supply. In addition, a total of about 14,000 acre-feet of shallow seepage was captured by French drains adjacent to the North and West Dams and used for municipal supply, irrigation, or returned to the reservoir.From 2002 through 2009, about 86,000 acre-feet of water seeped beneath the reservoir to recharge the underlying Navajo Sandstone aquifer. Water-quality sampling was conducted at various monitoring wells in Sand Hollow to evaluate the timing and location of reservoir recharge moving through the aquifer. Tracers of reservoir recharge include major and minor dissolved inorganic ions, tritium, dissolved organic carbon, chlorofluorocarbons, sulfur hexafluoride, and noble gases. By 2010, this recharge arrived at monitoring wells within about 1,000 feet of the reservoir.

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.

Hydrogeologic characteristics and water quality of a confined sand unit in the surficial aquifer system, Hunter Army Airfield, Chatham County, Georgia

Science.gov (United States)

Gonthier, Gerard

2012-01-01

An 80-foot-deep well (36Q397, U.S. Geological Survey site identification 320146081073701) was constructed at Hunter Army Airfield to assess the potential of using the surficial aquifer system as a water source to irrigate a ballfield complex. A 300-foot-deep test hole was drilled beneath the ballfield complex to characterize the lithology and water-bearing characteristics of sediments above the Upper Floridan aquifer. The test hole was then completed as well 36Q397 open to a 19-foot-thick shallow, confined sand unit contained within the surficial aquifer system. A single-well, 24-hour aquifer test was performed by pumping well 36Q397 at a rate of 50 gallons per minute during July 13-14, 2011, to characterize the hydrologic properties of the shallow, confined sand unit. Two pumping events prior to the aquifer test affected water levels. Drawdown during all three pumping events and residual drawdown during recovery periods were simulated using the Theis formula on multiple changes in discharge rate. Simulated drawdown and residual drawdown match well with measured drawdown and residual drawdown using values of horizontal hydraulic conductivity and specific storage, which are typical for a confined sand aquifer. Based on the hydrologic parameters used to match simulated drawdown and residual drawdown to measured drawdown and residual drawdown, the transmissivity of the sand was determined to be about 400 feet squared per day. The horizontal hydraulic conductivity of the sand was determined to be about 20 feet per day. Analysis of a water-quality sample indicated that the water is suitable for irrigation. Sample analysis indicated a calcium-carbonate type water having a total dissolved solids concentration of 39 milligrams per liter. Specific conductance and concentrations of all analyzed constituents were below those that would be a concern for irrigation, and were below primary and secondary water-quality criteria levels.

Transport of barium through dolomite rocks under the presence of guar gum and brine salinities of hydraulic fracturing wastewater

Science.gov (United States)

Ebrahimi, P.; Vilcaez, J.

2017-12-01

Hydraulic fracturing wastewater (HFW) containing high concentrations of Ba, is commonly disposed into the deep saline aquifers. We investigate the effect of brine salinity, competing cations (Ca and Mg), and guar gum (most common fracturing viscosifier) on the sorption and transport of Ba through dolomite rocks. To this aim, we have conducted batch sorption and core-flooding experiments at both ambient (22°C) and deep subsurface (60°C) temperature conditions. The effect of mineral composition is assessed by comparing batch and core-flooding experimental results obtained with sandstone and dolomite rocks. Batch sorption experiments conducted using powdered dolomite rocks (500-600 µm particle size) revealed that Ba sorption on dolomite greatly decreases with increasing brine salinity (0 - 180,000 mg-NaCl/L), and that at brine salinities of HFW, chloro-complexation reactions between Ba and Cl ions and changes in pH (that results from dolomite dissolution) are the controlling factors of Ba sorption on dolomite. Organo-complexation reactions between Ba and guar gum, and competition of Ba with common cations (Ca and Mg) for hydration sites of dolomite, play a secondary role. This finding is in accordance with core-flooding experimental results, showing that the transport of Ba through synthetic dolomite rocks of high flow properties (25-29.6% porosity, 9.6-13.7 mD permeability), increases with increasing brine salinity (0-180,000 mg-NaCl/L), while the presence of guar gum (50-500 mg/L) does not affect the transport of Ba. On the other hand, core-flooding experiments conducted using natural dolomite core plugs (6.5-8.6% porosity, 0.06-0.3 mD permeability), indicates that guar gum can clog the pore throats of tight dolomite rocks retarding the transport of Ba. Results of our numerical simulation studies indicate that the mechanism of Ba sorption on dolomite can be represented by a sorption model that accounts for both surface complexation reactions on three distinct

The in-situ decontamination of sand and gravel aquifers by chemically enhanced solubilization of multiple-compound DNAPLs with surfactant solutions. Phase 1: Laboratory and pilot field-scale testing. Phase 2: Solubilization test and partitioning interwell tracer tests. Final report

International Nuclear Information System (INIS)

1997-01-01

Laboratory, numerical simulation, and field studies have been conducted to assess the potential use of micellar-surfactant solutions to solubilize chlorinated solvents contaminating sand and gravel aquifers. Ninety-nine surfactants were screened for their ability to solubilize trichloroethene (TCE), perchloroethylene (PCE), and carbon tetrachloride (CTET). The field test was conducted in the alluvial aquifer which is located 20 to 30 meters beneath a vapor degreasing operation at Paducah Gaseous Diffusion Plant. This aquifer has become contaminated with TCE due to leakage of perhaps 40,000 liters of TCE, which has generated a plume of dissolved TCE extending throughout an area of approximately 3 km 2 in the aquifer. Most of the TCE is believed to be present in the overlying lacustrine deposits and in the aquifer itself as a dense, non-aqueous phase liquid, or DNAPL. The objective of the field test was to assess the efficacy of the surfactant for in situ TCE solubilization. Although the test demonstrated that sorbitan monooleate was unsuitable as a solubilizer in this aquifer, the single-well test was demonstrated to be a viable method for the in situ testing of surfactants or cosolvents prior to proceeding to full-scale remediation

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.

Reactive transport at the pore-scale: Geological Labs on Chip studies (GLoCs) for CO2 storage in saline aquifers

Science.gov (United States)

Azaroual, M. M.; Lassin, A., Sr.; André, L., Sr.; Devau, N., Sr.; Leroy, P., Sr.

2017-12-01

The near well bore of CO2 injection in saline aquifer is the main sensitive part of the targeted carbone storage reservoirs. The recent development of microfluidics tools mimicking porous media of geological reservoirs allowed studying physical, physico-chemical and thermodynamic mechanisms. We used the GLoCs "Geological Labs on Chip" to study dynamic and reactive transport processes at the pore scale induced by the CO2 geological storage. The present work is a first attempt to reproduce, by reactive transport modeling, an experiment of calcium carbonate precipitation during the co-injection of two aqueous solutions in a GLoC device. For that purpose, a new kinetics model, based on the transition-state-theory and on surface complexation modeling, was developed to describe the co-precipitation of amorphous calcium carbonate (ACC) and calcite. ACC precipitates and creates surface complexation sites from which calcite can nucleate and create new surface complexation sites. When the kinetics of calcite precipitation are fast enough, the consumption of matter leads to the dissolution of ACC. The modeling results were first compared to batch experiments (from the literature) and then applied with success to dynamic experiment observations carried out on a GLoC device (from the literature). On the other hand, we evaluated the solubility of CO2 in capillary waters that increases between 5 to 10 folds for reservoir conditions (200 bar and 100°C) compared to the bulk water. The GLoCs tools started to address an excellent and much finer degree of processes control (reactive transport processes, mixing effects, minerals precipitation and dissolution kinetics, etc.) thanks to in situ analysis and characterization techniques, allowing access in real time to relevant properties. Current investigations focus on key parameters influencing the flowing dynamics and trapping mechanisms (relative permeability, capillary conditions, kinetics of dissolution and precipitation of minerals).

Analysis of the potential formation of a Breccia chimney beneath the WIPP repository

International Nuclear Information System (INIS)

Spiegler, P.

1982-05-01

This report evaluates the potential formation of a Breccia pipe beginning at the Bell Canyon aquifer beneath the WIPP repository and the resulting release of radioactivity to the surface. Rock mechanics considerations indicate that the formation of a Breccia pipe by collapse of a cavern is not reasonable. Even if rock mechanics is ignored, the overlying strata act as a barrier and would prevent the release of radioactivity to the biosphere. Gradual formation of a Breccia pipe is so slow that the plutonium-239 in the waste (one of the most important long-lived components) would decay during formation. If Bell Lake and San Simon Sinks are the surface manifestation of a regional deep dissolution wedge, such a wedge is too far removed to represent pipe forming activity near the WIPP site. The formation of a Breccia pipe under the WIPP repository is highly unlikely. If it did occur, the concentration of plutonium-239 in brine reaching the surface would be less than the maximum permissible concentration in water specified in the Code of Federal Regulation Title 10, part 20

The in-situ decontamination of sand and gravel aquifers by chemically enhanced solubilization of multiple-compound DNAPLs with surfactant solutions: Phase 1 -- Laboratory and pilot field-scale testing and Phase 2 -- Solubilization test and partitioning and interwell tracer tests. Final report

Energy Technology Data Exchange (ETDEWEB)

NONE

1997-10-24

Laboratory, numerical simulation, and field studies have been conducted to assess the potential use of micellar-surfactant solutions to solubilize chlorinated solvents contaminating sand and gravel aquifers. Ninety-nine surfactants were screened for their ability to solubilize trichloroethene (TCE), perchloroethylene (PCE), and carbon tetrachloride (CTET). The field test was conducted in the alluvial aquifer which is located 20 to 30 meters beneath a vapor degreasing operation at Paducah Gaseous Diffusion Plant. This aquifer has become contaminated with TCE due to leakage of perhaps 40,000 liters of TCE, which has generated a plume of dissolved TCE extending throughout an area of approximately 3 km{sup 2} in the aquifer. Most of the TCE is believed to be present in the overlying lacustrine deposits and in the aquifer itself as a dense, non-aqueous phase liquid, or DNAPL. The objective of the field test was to assess the efficacy of the surfactant for in situ TCE solubilization. Although the test demonstrated that sorbitan monooleate was unsuitable as a solubilizer in this aquifer, the single-well test was demonstrated to be a viable method for the in situ testing of surfactants or cosolvents prior to proceeding to full-scale remediation.

P-wave velocity structure beneath the northern Antarctic Peninsula

Science.gov (United States)

Park, Y.; Kim, K.; Jin, Y.

2010-12-01

We have imaged tomographically the tree-dimensional velocity structure of the upper mantle beneath the northern Antarctic Peninsula using teleseismic P waves. The data came from the seven land stations of the Seismic Experiment in Patagonia and Antarctica (SEPA) campaigned during 1997-1999, a permanent IRIS/GSN station (PMSA), and 3 seismic stations installed at scientific bases, Esperanza (ESPZ), Jubany (JUBA), and King Sejong (KSJ), in South Shetland Islands. All of the seismic stations are located in coast area, and the signal to noise ratios (SNR) are very low. The P-wave model was inverted from 95 earthquakes resulting in 347 ray paths with P- and PKP-wave arrivals. The inverted model shows a strong low velocity anmaly beneath the Bransfield Strait, and a fast anomaly beneath the South Shetland Islands. The low velocity anomaly beneath the Bransfield might be due to a back arc extension, and the fast velocity anomaly beneath the South Shetland Islands could indicates the cold subducted slab.

Stable groundwater quality in deep aquifers of Southern Bangladesh: The case against sustainable abstraction

International Nuclear Information System (INIS)

Ravenscroft, P.; McArthur, J.M.; Hoque, M.A.

2013-01-01

In forty six wells > 150 m deep, from across the arsenic-polluted area of south-central Bangladesh, groundwater composition remained unchanged between 1998 and 2011. No evidence of deteriorating water quality was found in terms of arsenic, iron, manganese, boron, barium or salinity over this period of 13 years. These deep tubewells have achieved operating lives of more than 20 years with minimal institutional support. These findings confirm that tubewells tapping the deep aquifers in the Bengal Basin provide a safe, popular, and economic, means of arsenic mitigation and are likely to do so for decades to come. Nevertheless, concerns remain about the sustainability of a resource that could serve as a source of As-safe water to mitigate As-pollution in shallower aquifers in an area where tens of millions of people are exposed to dangerous levels of arsenic in well water. The conjunction of the stable composition in deep groundwater and the severe adverse health effects of arsenic in shallow groundwater lead us to challenge the notion that strong sustainability principles should be applied to the management of deep aquifer abstraction in Bangladesh is, the notion that the deep groundwater resource should be preserved for future generations by protecting it from adverse impacts, probably of a minor nature, that could occur after a long time and might not happen at all. Instead, we advocate an ethical approach to development of the deep aquifer, based on adaptive abstraction management, which allows possibly unsustainable exploitation now in order to alleviate crippling disease and death from arsenic today while also benefiting future generations by improving the health, education and economy of living children. - Highlights: • Tens of millions of people in Bangladesh are affected by arsenic pollution of groundwater. • Deep wells in potentially non-renewable aquifers are the dominant form of mitigation. • Water quality in these aquifers has remained stable for 13

Stable groundwater quality in deep aquifers of Southern Bangladesh: The case against sustainable abstraction

Energy Technology Data Exchange (ETDEWEB)

Ravenscroft, P., E-mail: pravenscroft@unicef.org [UNICEF, BSL Office Complex, Minto Road, Dhaka 1000 (Bangladesh); McArthur, J.M.; Hoque, M.A. [Earth Sciences, University College London, Gower Street, London WC1E 6BT (United Kingdom)

2013-06-01

In forty six wells > 150 m deep, from across the arsenic-polluted area of south-central Bangladesh, groundwater composition remained unchanged between 1998 and 2011. No evidence of deteriorating water quality was found in terms of arsenic, iron, manganese, boron, barium or salinity over this period of 13 years. These deep tubewells have achieved operating lives of more than 20 years with minimal institutional support. These findings confirm that tubewells tapping the deep aquifers in the Bengal Basin provide a safe, popular, and economic, means of arsenic mitigation and are likely to do so for decades to come. Nevertheless, concerns remain about the sustainability of a resource that could serve as a source of As-safe water to mitigate As-pollution in shallower aquifers in an area where tens of millions of people are exposed to dangerous levels of arsenic in well water. The conjunction of the stable composition in deep groundwater and the severe adverse health effects of arsenic in shallow groundwater lead us to challenge the notion that strong sustainability principles should be applied to the management of deep aquifer abstraction in Bangladesh is, the notion that the deep groundwater resource should be preserved for future generations by protecting it from adverse impacts, probably of a minor nature, that could occur after a long time and might not happen at all. Instead, we advocate an ethical approach to development of the deep aquifer, based on adaptive abstraction management, which allows possibly unsustainable exploitation now in order to alleviate crippling disease and death from arsenic today while also benefiting future generations by improving the health, education and economy of living children. - Highlights: • Tens of millions of people in Bangladesh are affected by arsenic pollution of groundwater. • Deep wells in potentially non-renewable aquifers are the dominant form of mitigation. • Water quality in these aquifers has remained stable for 13

Alternative Options for Safe Drinking Water in Arsenic and Salinity Affected Bornal-Iliasabad Union of Kalia Upazila, Narail District, Bangladesh

Science.gov (United States)

Rahman, M. M.; Hasan, M. A.; Ahmed, K. M.; Nawrin, N.

2016-12-01

The study area, Bornal-Ilisabad union, Kalia, Narail is one of the most vulnerable areas of Bangladesh in terms of access to safe drinking water. Shallow groundwater of this area is highly arsenic contaminated (mostly >500 μg/L) and deep groundwater is saline (EC ranges 1 to 8 mS/cm). Local communities rely on rainwater for drinking and cooking purposes during the monsoon and rest of the year they use surface water from pond which are mostly polluted. In areas where surface water is not available people are compelled to use arsenic contaminated groundwater and thus exposing themselves to serious health hazard. Principal objective of the research is to evaluate the effectiveness of managed aquifer recharge (MAR) and subsurface arsenic removal (SAR) technology in mitigating groundwater salinity and arsenic, to provide alternative sources of safe water. Surface water (pond water) and rainwater collected from roof top are used as source water to be recharged into the target aquifer for the MAR system. Source water is filtered through a sand filtration unit to remove turbidity and microorganisms before recharging through infiltration wells. For SAR system, on the other hand, a certain volume (2000L) of groundwater is abstracted from the target aquifer and then aerated for about half an hour to saturate with oxygen. The oxygenated water is injected into the aquifer and kept there for 6-8 hours and then abstracted for use. The MAR system constructed in the study area is found very effective in reducing groundwater salinity. The electrical conductivity (EC) of the groundwater of MAR system has been reduced 72-81% from the initial EC value of 3.4 mS/cm. A significant improvement in groundwater arsenic and iron concentration is also observed. The system is yielding groundwater with arsenic within permissible limit of Bangladesh drinking water standard (50 μg/L) which was 100 μg/L before introduction of MAR system. The SAR system is also found effective in reducing

Groundwater-Quality Survey of the South Coast Aquifer of Puerto Rico, April 2 through May 30, 2007

Science.gov (United States)

Rodriguez, Jose M.; Gómez-Gómez, Fernando

2009-01-01

The increased potential for variability of groundwater quality in the South Coast aquifer of Puerto Rico due to saline water encroachment from the Caribbean Sea and from deep parts of the aquifer has become a major concern of water planners and managers. In an effort to determine the extent and sources of this encroachment, the U.S. Geological Survey (USGS) and the Puerto Rico Department of Natural and Environmental Resources conducted a synoptic groundwater-quality survey from April 2 through May 30, 2007, for the South Coast aquifer between Ponce and Arroyo (fig. 1). Groundwater resources in this aquifer extend 150 square miles in south-central Puerto Rico and provide an estimated 44.2 million gallons per day (Mgal/d) or about 61 percent of the total water needs. This amount includes: 15.3 Mgal/d for irrigation, 27.4 Mgal/d for public supply, and 1.5 Mgal/d for industrial and other uses (W.L. Molina-Rivera, U.S. Geological Survey, written commun., 2007). Since 1980 when most of the south coastal plain was intensively cultivated for sugarcane, total groundwater withdrawals have declined about 32 Mgal/d with the greatest decline occurring in irrigation (37.2 Mgal/d) and the greatest increase occurring in public supply (5.5 Mgal/d). Although withdrawals have declined substantially, a major concern is that aquifer recharge provided by irrigation return flow from surface-water irrigation canals has essentially dropped to zero because of the large-scale implementation of groundwater drip irrigation systems.

Using electrical resistivity tomography to assess the effectiveness of managed aquifer recharge in a salinized coastal aquifer.

Science.gov (United States)

García-Menéndez, Olga; Ballesteros, Bruno J; Renau-Pruñonosa, Arianna; Morell, Ignacio; Mochales, Tania; Ibarra, Pedro I; Rubio, Félix M

2018-01-27

Over 40 years, the detrital aquifer of the Plana de Castellón (Spanish Mediterranean coast) has been subjected to seawater intrusion because of long dry periods combined with intensive groundwater exploitation. Against this backdrop, a managed artificial recharge (MAR) scheme was implemented to improve the groundwater quality. The large difference between the electrical conductivity (EC) of the ambient groundwater (brackish water due to marine intrusion) and the recharge water (freshwater) meant that there was a strong contrast between the resistivities of the brackish water saturated zone and the freshwater saturated zone. Electrical resistivity tomography (ERT) can be used for surveying similar settings to evaluate the effectiveness of artificial recharge schemes. By integrating geophysical data with lithological information, EC logs from boreholes, and hydrochemical data, we can interpret electrical resistivity (ER) with groundwater EC values and so identify freshwater saturated zones. Using this approach, ERT images provided a high-resolution spatial characterization and an accurate picture of the shape and extent of the recharge plume of the MAR site. After 5 months of injection, a freshwater plume with an EC of 400-600 μS/cm had formed that extended 400 m in the W-E direction, 250 m in the N-S direction, and to a depth of 40 m below piezometric level. This study also provides correlations between ER values with different lithologies and groundwater EC values that can be used to support other studies.

Sub-crustal seismic activity beneath Klyuchevskoy Volcano

Science.gov (United States)

Carr, M. J.; Droznina, S.; Levin, V. L.; Senyukov, S.

2013-12-01

Seismic activity is extremely vigorous beneath the Klyuchevskoy Volcanic Group (KVG). The unique aspect is the distribution in depth. In addition to upper-crustal seismicity, earthquakes take place at depths in excess of 20 km. Similar observations are known in other volcanic regions, however the KVG is unique in both the number of earthquakes and that they occur continuously. Most other instances of deep seismicity beneath volcanoes appear to be episodic or transient. Digital recording of seismic signals started at the KVG in early 2000s.The dense local network reliably locates earthquakes as small as ML~1. We selected records of 20 earthquakes located at depths over 20 km. Selection was based on the quality of the routine locations and the visual clarity of the records. Arrivals of P and S waves were re-picked, and hypocentral parameters re-established. Newl locations fell within the ranges outlined by historical seismicity, confirming the existence of two distinct seismically active regions. A shallower zone is at ~20 km depth, and all hypocenters are to the northeast of KVG, in a region between KVG and Shiveluch volcano. A deeper zone is at ~30 km, and all hypocenters cluster directly beneath the edifice of the Kyuchevskoy volcano. Examination of individual records shows that earthquakes in both zones are tectonic, with well-defined P and S waves - another distinction of the deep seismicity beneath KVG. While the upper seismic zone is unquestionably within the crust, the provenance of the deeper earthquakes is enigmatic. The crustal structure beneath KVG is highly complex, with no agreed-upon definition of the crust-mantle boundary. Rather, a range of values, from under 30 to over 40 km, exists in the literature. Similarly, a range of velocity structures has been reported. Teleseismic receiver functions (RFs) provide a way to position the earthquakes with respect to the crust-mantle boundary. We compare the differential travel times of S and P waves from deep

Hydrogeological characterization of the Nador Plio-Quaternary aquifer, Tipaza (Algeria); Caracterizacion hidrogeologica del acuifero pliocuaternario de Nador, Tipaza (Argelia)

Energy Technology Data Exchange (ETDEWEB)

Bouderbala, A.; Remini, B.; Pulido-Bosch, A.

2014-06-01

This paper focuses on the hydrogeological and hydrochemical knowledge of the Nador Plio-Quaternary aquifer in Tipaza, situated along the Algerian coastline. It includes the identification of the hydrodynamic aquifer, hydrogeological and piezometric characteristics and, finally, an overview of the hydro-geochemistry of the area. We carried out this study between 2008 and 2013, with piezometric and hydrochemical monitoring of 24 wells in the study area. The physicochemical analysis of water shows that 25 % of the wells in the coastal zone have values of electrical conductivity greater than 3000 μS/cm The Mg{sup 2}+/Ca{sup 2}+ ratio is also higher than one and there are sodium chloride facies due to the mix of freshwater with seawater exceeding 10 % in some places. However, the comparison of the salinity of the groundwater during the period 2008-2013 with 1988-2004 indicates that there is a low dilution due to the reduction of pumping in the aquifer after the construction of the Boukourdane dam. There has also been a more rainy period and a possible return flow from irrigation in the area. (Author)

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

Science.gov (United States)

Freethey, Geoffrey W.; Stolp, Bernard J.

2010-01-01

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

Denitrification and dilution along fracture flowpaths influence the recovery of a bedrock aquifer from nitrate contamination

Energy Technology Data Exchange (ETDEWEB)

Kim, Jonathan J., E-mail: jon.kim@vermont.gov [Vermont Geological Survey, 1 National Life Drive, Main 2, Montpelier, VT 05620 (United States); Comstock, Jeff [Vermont Agency of Agriculture, 116 State Street, Montpelier, VT 05620 (United States); Ryan, Peter [Dept. of Geology, Middlebury College, Middlebury, VT 05753 (United States); Heindel, Craig [Waite-Heindel Environmental Management, 7 Kilburn Street, Suite 301, Burlington, VT 05401 (United States); Koenigsberger, Stephan [Dept. of Geology, Middlebury College, Middlebury, VT 05753 (United States)

2016-11-01

In 2000, elevated nitrate concentrations ranging from 12 to 34 mg/L NO{sub 3}−N were discovered in groundwater from numerous domestic bedrock wells adjacent to a large dairy farm in central Vermont. Long-term plots and contours of nitrate vs. time for bedrock wells showed “little/no”, “moderate”, and “large” change patterns that were spatially separable. The metasedimentary bedrock aquifer is strongly anisotropic and groundwater flow is controlled by fractures, bedding/foliation, and basins and ridges in the bedrock surface. Integration of the nitrate concentration vs. time data and the physical and chemical aquifer characterization suggest two nitrate sources: a point source emanating from a waste ravine and a non-point source that encompasses the surrounding fields. Once removed, the point source of NO{sub 3} (manure deposited in a ravine) was exhausted and NO{sub 3} dropped from 34 mg/L to < 10 mg/L after ~ 10 years; however, persistence of NO{sub 3} in the 3 to 8 mg/L range (background) reflects the long term flux of nitrates from nutrients applied to the farm fields surrounding the ravine over the years predating and including this study. Inferred groundwater flow rates from the waste ravine to either moderate change wells in basin 2 or to the shallow bedrock zone beneath the large change wells are 0.05 m/day, well within published bedrock aquifer flow rates. Enrichment of {sup 15}N and {sup 18}O in nitrate is consistent with lithotrophic denitrification of NO{sub 3} in the presence of dissolved Mn and Fe. Once the ravine point-source was removed, denitrification and dilution collectively were responsible for the down-gradient decrease of nitrate in this bedrock aquifer. Denitrification was most influential when NO{sub 3}−N was > 10 mg/L. Our multidisciplinary methods of aquifer characterization are applicable to groundwater contamination in any complexly-deformed and metamorphosed bedrock aquifer. - Highlights: • Bedrock wells contaminated

Using Oil and Gas Well Log Records to Understand Possible Connections Between Wastewater Injection Zones and Usable Groundwater Aquifers in California

Science.gov (United States)

Shimabukuro, D.; Haugen, E. A.; Battistella, C.; Treguboff, E. W.; Kale, J. M.

2015-12-01

Although the disposal of produced water in wastewater injection wells has been occurring in California for decades, it is not clear whether injected fluids may be migrating into usable groundwater aquifers. One problem is the poor characterization of federally-protected (oil and gas well records collected by the California Division of Oil, Gas, and Geothermal Resources (DOGGR). These scanned records contain two useful sources of information. First, geophysical well logs, such those measuring resistivity and porosity, can be used to determine aquifer salinity. This allows a three-dimensional understanding of the distribution of protected groundwater. Second, driller's logs contain lithological descriptions at depth. These lithologies can be used to construct a three-dimensional texture model, which can then be used in a groundwater flow model. A large number of undergraduate researchers at CSU Sacramento and CSU Long Beach have been collecting information on well records in the Ventura Basin and the Southern San Joaquin Valley. Each well record is examined with basic metadata entered into an online database in an effort to identify appropriate geophysical well logs and driller's logs. High-quality driller's logs are coded and used to create three-dimensional framework models for each well field. The geophysical logs are digitized and will be used to determine aquifer salinity. In addition, we are using information from the DOGGR well records to investigate wellbore integrity, waste disposal and waterflood injection volumes, and the possibility of induced seismicity. This project is part of the broader effort of the California State Water Resources Control Board to implement Senate Bill 4.

Rainwater lens dynamics and mixing between infiltrating rainwater and upward saline groundwater seepage beneath a tile-drained agricultural field

NARCIS (Netherlands)

Louw, de P.G.B.; Eeman, S.; Oude Essink, G.H.P.; Vermue, E.; Post, V.E.A.

2013-01-01

Thin rainwater lenses (RW-lenses) near the land surface are often the only source of freshwater in agricultural areas with regionally-extensive brackish to saline groundwater. The seasonal and inter-annual dynamics of these lenses are poorly known. Here this knowledge gap is addressed by

Water-rock interaction and geochemistry of groundwater from the Ain Azel aquifer, Algeria.

Science.gov (United States)

Belkhiri, Lazhar; Mouni, Lotfi; Tiri, Ammar

2012-02-01

Hydrochemical, multivariate statistical, and inverse geochemical modeling techniques were used to investigate the hydrochemical evolution within the Ain Azel aquifer, Algeria. Cluster analysis based on major ion contents defined 3 main chemical water types, reflecting different hydrochemical processes. The first group water, group 1, has low salinity (mean EC = 735 μS/cm). The second group waters are classified as Cl-HCO(3)-alkaline earth type. The third group is made up of water samples, the cation composition of which is dominated by Ca and Mg with anion composition varying from dominantly Cl to dominantly HCO(3) plus SO(4). The varifactors obtained from R-mode FA indicate that the parameters responsible for groundwater quality variations are mainly related to the presence and dissolution of some carbonate, silicate, and evaporite minerals in the aquifer. Inverse geochemical modeling along groundwater flow paths indicates the dominant processes are the consumption of CO(2), the dissolution of dolomite, gypsum, and halite, along with the precipitation of calcite, Ca-montmorillonite, illite, kaolinite, and quartz. © Springer Science+Business Media B.V. 2011

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

Epigenetic zonation and fluid flow history of uranium-bearing fluvial aquifer systems, south Texas uranium province. Report of Investigations No. 119

International Nuclear Information System (INIS)

Galloway, W.E.

1982-01-01

The Oligocene-Miocene fluvial uranium host aquifers of the South Texas uranium province were deposited principally as syndepositionally oxidized sands and muds. Early intrusion of reactive sulfide-enriched waters produced large intrastratal islands of epigenetic sulfidic alteration, which contain isotopically heavy pyrite exhibiting unique replacement textures. The only known reservoir containing such sulfidic waters is the deeply buried Mesozoic carbonate section beneath the thick, geopressured Tertiary basin fill. Thermobaric waters were expulsed upward along major fault zones into shallow aquifers in response to a pressure head generated by compaction and dehydration in the abyssal ground-water regime. Vertical migration of gaseous hydrogen sulfide was less important. Repeated flushing of the shallow aquifers by oxidizing meteoric waters containing anomalous amounts of uranium, selenium, and molybdenum alternating with sulfidic thermobaric waters caused cyclic precipitation and oxidation of iron disulfide. Uranium deposits formed along hydrologically active oxidation interfaces separating epigenetic sulfidic and epigenetic oxidation zones. Multiple epigenetic events are recorded in imperfectly superimposed, multiple mineralization fronts, in regional and local geometric relations between different alteration zones, and in the bulk matrix geochemistry and mineralogy of alteration zones. The dynamic mineralization model described in this report may reflect processes active in many large, depositionally active basins

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

Revised shallow and deep water-level and storage-volume changes in the Equus Beds Aquifer near Wichita, Kansas, predevelopment to 1993

Science.gov (United States)

Hansen, Cristi V.; Lanning-Rush, Jennifer L.; Ziegler, Andrew C.

2013-01-01

Beginning in the 1940s, the Wichita well field was developed in the Equus Beds aquifer in southwestern Harvey County and northwestern Sedgwick County to supply water to the city of Wichita. The decline of water levels in the aquifer was noted soon after the development of the Wichita well field began. Development of irrigation wells began in the 1960s. City and agricultural withdrawals led to substantial water-level declines. Water-level declines enhanced movement of brines from past oil and gas activities near Burrton, Kansas and enhanced movement of natural saline water from the Arkansas River into the well field area. Large chloride concentrations may limit use or require the treatment of water from the well field for irrigation or public supply. In 1993, the city of Wichita adopted the Integrated Local Water Supply Program (ILWSP) to ensure an adequate water supply for the city through 2050 and as part of its effort to effectively manage the part of the Equus Beds aquifer it uses. ILWSP uses several strategies to do this including the Equus Beds Aquifer Storage and Recovery (ASR) project. The purpose of the ASR project is to store water in the aquifer for later recovery and to help protect the aquifer from encroachment of a known oilfield brine plume near Burrton and saline water from the Arkansas River. As part of Wichita’s ASR permits, Wichita is prohibited from artificially recharging water into the aquifer in a Basin Storage area (BSA) grid cell if water levels in that cell are above the January 1940 water levels or are less than 10 feet below land surface. The map previously used for this purpose did not provide an accurate representation of the shallow water table. The revised predevelopment water-level altitude map of the shallow part of the aquifer is presented in this report. The city of Wichita’s ASR permits specify that the January 1993 water-level altitudes will be used as a lower baseline for regulating the withdrawal of artificial rechage

Overview--Development of a geodatabase and conceptual model of the hydrogeologic units beneath Air Force Plant 4 and Naval Air Station-Joint Reserve Base Carswell Field, Fort Worth, Texas

Science.gov (United States)

Shah, Sachin D.

2004-01-01

Air Force Plant 4 (AFP4) and adjacent Naval Air Station-Joint Reserve Base Carswell Field (NAS–JRB) at Fort Worth, Tex., constitute a contractor-owned, government-operated facility that has been in operation since 1942. Contaminants from the 3,600-acre facility, primarily volatile organic compounds (VOCs) and metals, have entered the ground-water-flow system through leakage from waste-disposal sites and from manufacturing processes. Environmental data collected at AFP4 and NAS–JRB during 1993–2002 created the need for consolidation of the data into a comprehensive temporal and spatial geodatabase. The U.S. Geological Survey (USGS), in cooperation with the U.S. Air Force Aeronautical Systems Center Environmental Management Directorate, developed a comprehensive geodatabase of temporal and spatial environmental data associated with the hydrogeologic units beneath the facility. A three-dimensional conceptual model of the hydrogeologic units integrally linked to the geodatabase was designed concurrently. Three hydrogeologic units—from land surface downward, the alluvial aquifer, the GoodlandWalnut confining unit, and the Paluxy aquifer—compose the subsurface of interest at AFP4 and NAS–JRB. The alluvial aquifer consists primarily of clay and silt with sand and gravel channel deposits that might be interconnected or interfingered. The Goodland-Walnut confining unit directly underlies the alluvial aquifer and consists of limestone, marl, shale, and clay. The Paluxy aquifer is composed of dense mudstone and fine- to coarse-grained sandstone

Application of isotope study of the hydrogeological aquifers of the Yarmouk basin

International Nuclear Information System (INIS)

Sharida, A.R.; Jubeili, Y.

2001-05-01

Environmental isotopic variations have been used to investigate the source of recharge and age in the basaltic and deep limestone aquifers system in the Yarmouk basin, SW of Syria. Isotopic results show that recharge of basaltic aquifer is directly related to infiltration of rainwater from high and transitional zones. However, the homogeneity noted of stable and radioactive isotopes values (δ 18 O= -5.58± 0.25%, 14 C=46.2± 4.45 % pmc) in Laja plateau and central zone, confirm the mechanism of common recharge and critical role of this plateau in absorbing great amount of precipitation. In addition these values indicate, to a high rate mixing taking place in this plateau and the central zone. In the Kahiel area, the groundwater is of recent age as shown from the high values of 14 C activity ( 14 C= 66.3 ± 5.3 % pcm) accompanied by enriched 18 O (δ 18 O=-4.7±0.22 %). The recharge of groundwater is related to the leakage of water from dams and drainage network. The tectonic setting in this area constitutes an additional factor in increasing this recharge. Netpath model was used to determine the age of groundwater. the age of groundwater in the basaltic aquifer is generally modern and reaches 2000 y BP in discharge area. Preliminary conclusion of deep limestone aquifer, indicate that its groundwater occur under high piezometric pressure. The salinity is less than 1g/L and the temperature water varied between 35 to 45 degreed centigrade. The low 14 C activities in deep groundwater suggest pleistocene and holocene recharge, although their stable isotopes values indicate recharge by modern meteoric precipitation. The corrected age of this groundwater determined by Netpath model indicate that this age fall between recent water in recharge area and 20 Ky BP. (author)

DNAPL migration in a coastal plain aquifer

International Nuclear Information System (INIS)

DiGuiseppi, W.H.; Jung, A.D.

1995-01-01

Soil and ground water at the Dover Gas Light Superfund Site, a former manufactured gas plant (1859 to 1948), are contaminated with polynuclear aromatic hydrocarbons and volatile organic compounds. Contaminants of concern include light aromatics, such as benzene, toluene, ethylbenzene, and xylenes (BTEX), and heavy aromatics, including naphthalene, acenaphthylene, phenanthrene, and benzo(a)pyrene. Although ground-water contaminant levels are elevated near the site, only naphthalene and acenaphthylene are present within an order of magnitude of their solubility limits, indicating the possibility of dense non-aqueous phase liquids (DNAPL) in the subsurface. The unconfined Columbia Aquifer, which is characterized by interfingering and discontinuous sand, silt, and clay Coastal Plain deposits, overlies a clay aquitard at a depth of 60 feet. The ground water beneath the intermediate clay horizon exhibited little or no contamination, even immediately downgradient from the site. The relationship between the more permeable granular sand horizons and the less permeable interfingering clay zones controls the migration of both the aqueous-phase contamination and the DNAPL. A detailed horizontal and vertical characterization of the subsurface stratigraphy was critical to the accurate interpretation of the extent and magnitude of contamination and the identification and delineation of DNAPL zones

Study the mechanisms of recharge of the phreatic aquifers, south east egypt, using environmental isotopes and hydro geochemistry

International Nuclear Information System (INIS)

Hassan, T.M.; Awad, M.A.; Hamza, M.S.

1994-01-01

The recharge rate is the most critical factor to groundwater resources management especially in semi-arid and arid areas. This paper presents a study on the feasibility of a groundwater development plan for south east egypt area. Environmental stable isotopes (oxygen-18 and deuterium), and hydro geochemistry techniques were used to investigate the recharge sources of groundwater. The examined groundwater wells tap the quaternary, basement and Nubian sandstone aquifers. The isotopic compositions of these groundwater samples indicate that there is a mixing among three different sources of recharge, local precipitation, palaeo water and sea water intrusion along the coastal plain, from the hydrochemical point of view, the predominant water types reflect meteoric, as well as marine waters genesis. The changes in salinity depend upon the dissolution of terrestrial salts, distance from the catchment area and seepage from deep aquifers. 7 figs., 2 tabs

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.

Managing water and salinity with desalination, conveyance, conservation, waste-water treatment and reuse to counteract climate variability in Gaza

Science.gov (United States)

Rosenberg, D. E.; Aljuaidi, A. E.; Kaluarachchi, J. J.

2009-12-01

We include demands for water of different salinity concentrations as input parameters and decision variables in a regional hydro-economic optimization model. This specification includes separate demand functions for saline water. We then use stochastic non-linear programming to jointly identify the benefit maximizing set of infrastructure expansions, operational allocations, and use of different water quality types under climate variability. We present a detailed application for the Gaza Strip. The application considers building desalination and waste-water treatment plants and conveyance pipelines, initiating water conservation and leak reduction programs, plus allocating and transferring water of different qualities among agricultural, industrial, and urban sectors and among districts. Results show how to integrate a mix of supply enhancement, conservation, water quality improvement, and water quality management actions into a portfolio that can economically and efficiently respond to changes and uncertainties in surface and groundwater availability due to climate variability. We also show how to put drawn-down and saline Gaza aquifer water to more sustainable and economical use.

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

Geoelectric imaging for saline water intrusion in Geopark zone of Ciletuh Bay, Indonesia

Science.gov (United States)

Ardi, N. D.; Iryanti, M.; Asmoro, C. P.; Yusuf, A.; Sundana, A. N. A.; Safura, H. Y.; Fitri, M.; Anggraeni, M.; Kurniawan, R.; Afrianti, R.; Sumarni

2018-05-01

Saline water intrusion in estuary is an urgent ecological encounter across the world. The Ciletuh Bay, located in the southern Sukabumi district, is an area with high cultivated potential becoming one of the most important geology tourism zones in Indonesia. However, salt water intrusion along the creek is a natural spectacle that disturbs the economic growth of the whole region. This research was intended at plotting the subsurface level of saltwater interventions into aquifers at the northern part of Ciletuh creek, Indonesia. The study implemented geoelectric imaging methods. 37 imaging datum were acquired using Wenner array configuration. The saline water were identified across the study area. The result of two dimensional cross-sectional resistivity shows that there is an indication of sea content in our measured soil, i.e. the smallest resistivity value is 0.579 Ωm found at a depth of 12.4 m to 19.8 m at a track length of 35 m to 60 m is categorized in the clayey which shows low groundwater quality. However, when compared with the results of direct observation of groundwater from the wells of residents, the water obtained is brackish water. A water chemistry test is conducted to ascertain the initial results of this method so that a potential sea intrusion potential map can be interpreted more clearly. This can consequently help as an extrapolative model to define depth to saline water at any site within the saline water zone in the study area.

Water sources accessed by arid zone riparian trees in highly saline environments, Australia.

Science.gov (United States)

Costelloe, Justin F; Payne, Emily; Woodrow, Ian E; Irvine, Elizabeth C; Western, Andrew W; Leaney, Fred W

2008-05-01

The flow regimes of arid zone rivers are often highly variable, and shallow groundwater in the alluvial aquifers can be very saline, thus constraining the availability and quality of the major water sources available to riparian trees-soil water, shallow groundwater and stream water. We have identified water sources and strategies used by riparian trees in more highly saline and arid conditions than previously studied for riparian trees of arid zone rivers. Our research focused on the riparian species Eucalyptus coolabah, one of the major riparian trees of ephemeral arid zone rivers in Australia. The water sources available to this riparian tree were examined using delta(18)O isotope data from xylem, soil water, groundwater and surface water. Additionally, soil chloride and matric potential data were used to infer zones of water availability for root uptake. Despite the saline conditions, the trees used a mixture of soil water and groundwater sources, but they did not use surface water directly. The study identified three strategies used to cope with typically high groundwater and soil water salinities. Firstly, the trees preferentially grow in zones of most frequent flushing by infiltrating streamflow, such as the bank-tops of channels. Secondly, the trees limit water use by having low transpiration rates. Thirdly, the trees are able to extract water at very low osmotic potentials, with water uptake continuing at chloride concentrations of at least 20,000-30,000 mg L(-1).

Nonstationary porosity evolution in mixing zone in coastal carbonate aquifer using an alternative modeling approach.

Science.gov (United States)

Laabidi, Ezzeddine; Bouhlila, Rachida

2015-07-01

In the last few decades, hydrogeochemical problems have benefited from the strong interest in numerical modeling. One of the most recognized hydrogeochemical problems is the dissolution of the calcite in the mixing zone below limestone coastal aquifer. In many works, this problem has been modeled using a coupling algorithm between a density-dependent flow model and a geochemical model. A related difficulty is that, because of the high nonlinearity of the coupled set of equations, high computational effort is needed. During calcite dissolution, an increase in permeability can be identified, which can induce an increase in the penetration of the seawater into the aquifer. The majority of the previous studies used a fully coupled reactive transport model in order to model such problem. Romanov and Dreybrodt (J Hydrol 329:661-673, 2006) have used an alternative approach to quantify the porosity evolution in mixing zone below coastal carbonate aquifer at steady state. This approach is based on the analytic solution presented by Phillips (1991) in his book Flow and Reactions in Permeable Rock, which shows that it is possible to decouple the complex set of equation. This equation is proportional to the square of the salinity gradient, which can be calculated using a density driven flow code and to the reaction rate that can be calculated using a geochemical code. In this work, this equation is used in nonstationary step-by-step regime. At each time step, the quantity of the dissolved calcite is quantified, the change of porosity is calculated, and the permeability is updated. The reaction rate, which is the second derivate of the calcium equilibrium concentration in the equation, is calculated using the PHREEQC code (Parkhurst and Apello 1999). This result is used in GEODENS (Bouhlila 1999; Bouhlila and Laabidi 2008) to calculate change of the porosity after calculating the salinity gradient. For the next time step, the same protocol is used but using the updated porosity

Hydrogeology in the area of a freshwater lens in the Floridan aquifer system, northeast Seminole County, Florida

Science.gov (United States)

Phelps, G.G.; Rohrer, K.P.

1987-01-01

Northeast Seminole County, Florida, contains an isolated recharge area of the Floridan aquifer system that forms a freshwater lens completely surrounded by saline water. The freshwater lens covers an area of about 22 sq mi surrounding the town of Geneva, and generally is enclosed by the 25 ft land surface altitude contour. Thickness of the lens is about 350 ft in the center of the recharge area. The geohydrologic units in descending order consist of the post-Miocene sand and shell of the surficial aquifer; Miocene clay, sand, clay, and shell that form a leaky confining bed; and permeable Eocene limestones of the Floridan aquifer system. The freshwater lens is the result of local rainfall flushing ancient seawater from the Floridan aquifer system. Sufficient quantities of water for domestic and small public supply systems are available from the Floridan aquifer system in the Geneva area. The limiting factor for water supply in the area is the chemical quality of the water. Chloride concentrations range from recharge area to about 5,100 mg/L near the St. Johns River southeast of Geneva. Constituents analyzed included sulfate (range 1 to 800 mg/L), hardness (range 89 to 2,076 mg/L), and iron (range 34 to 6,600 mg/L). Because the freshwater lens results entirely from local recharge, the long-term sustained freshwater yield of the aquifer in the Geneva area depends on the local recharge rate. In 1982, recharge was about 13 inches (13.8 million gal/day). Average recharge for 1941 through 1970 was estimated to be about 11 inches (11.3 million gal/day). Freshwater that recharges the aquifer in the Geneva area is either pumped out or flows north and northeast to discharge near or in the St. Johns River. Average annual outflow from the lens is about 10 in/yr. No measurable change in the size or location of the freshwater lens has occurred since studies in the early 1950's. (Lantz-PTT)

Optimization of Design of Aquifer Storage and Recovery System (ASTR) for Enhanced Infiltration Rate with Reduced Cost at the Coastal Aquifers of South-Western Bangladesh

Science.gov (United States)

Nawrin, N.; Ahmed, K. M.; Rahman, M. M.

2016-12-01

Increasing salinity of natural drinking water sources has been reported as one of the many problems that affect low-income countries. Safe potable water sources in coastal Bangladesh have become contaminated by varying degrees of salinity due to saltwater intrusion, cyclone and storm surges and increased shrimp and crab farming along the coastal areas. This crisis is also exacerbated owing to climate change. The problem of salinity can have serious implications to public health. Here Managed Aquifer Recharge (MAR) has been ascertained as a better solution to overcome the fresh water shortage in the coastal belt of Bangladesh in terms of groundwater quality improvement and supply fresh water even during the dry period. 19 MAR systems have been built and tested in the area for providing community water supply by way of creating freshwater buffer zone in the brackish aquifers through artificial recharge of pond or rooftop rainwater. These existing ASTR schemes consist of sand filtration tank with 4 to 6 large diameter infiltration wells filled with sorted gravel. These larger diameter recharge wells make the construction and maintenance expensive and little difficult for the rural communities. Therefore, modification of design is required for enhancing infiltration rates with reduced costs. As the design of the existing MAR system have confronted some problems, the details of design, construction and performance have been studied from previous investigations and a new modified ASTR scheme has been demonstrated to amplify the infiltration rate along with monitoring scheme. Smaller 4 inch diameter empty recharge wells and PVC screen have been used in the newly developed design. Daily infiltration rate has been increased to 8 to 10 m3/d compared to 4 to 6 m3/d in the old design. Three layered sand filtration tank has been prepared by modification of an abandoned PSF. Time needed for lowering EC to acceptable limits has been found to be significantly lower than the pre

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.

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

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.

Groundwater Remediation in a Floodplain Aquifer at Shiprock, New Mexico

Energy Technology Data Exchange (ETDEWEB)

Peterson, Dave [Navarro Research and Engineering; Miller, David [Navarro Research and Engineering; Kautsky, Mark [U. S. Department of Energy, Office of Legacy Management; Dander, David [Navarro Research and Engineering; Nofchissey, Joni [Navajo Nation Division of Natural Resources

2016-03-06

A uranium- and vanadium-ore-processing mill operated from 1954 to 1968 within the Navajo Nation near Shiprock, New Mexico. By September 1986, all tailings and structures on the former mill property were encapsulated in a disposal cell built on top of two existing tailings piles on the Shiprock site (the site) [1]. Local groundwater was contaminated by multiple inorganic constituents as a result of the milling operations. The U.S. Department of Energy (DOE) took over management of the site in 1978 as part of the Uranium Mill Tailings Remedial Action (UMTRA) Project. The DOE Office of Legacy Management currently manages ongoing activities at the former mill facility, including groundwater remediation. Remediation activities are designed primarily to reduce the concentrations and total plume mass of the mill-related contaminants sulfate, uranium, and nitrate. In addition to contaminating groundwater in alluvial and bedrock sediments directly below the mill site, ore processing led to contamination of a nearby floodplain bordering the San Juan River. Groundwater in a shallow alluvial aquifer beneath the floodplain is strongly influenced by the morphology of the river channel as well as changing flows in the river, which provides drainage for regional runoff from the San Juan Mountains of Colorado. As part of a recent study of the floodplain hydrology, a revised conceptual model was developed for the alluvial aquifer along with an updated status of contaminant plumes that have been impacted by more than 10 years of groundwater pumping for site remediation purposes. Several findings from the recent study will be discussed here.

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

International Nuclear Information System (INIS)

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

2015-01-01

complex carbonate aquifer matrix and the successive inputs of nitrogen from various sources. - Highlights: • Examine high nitrate contents in the coastal carbonate aquifer of northeast China • Estimate renewal rates and mean residence times of groundwater in coastal aquifers • Evaluate the relation between groundwater age distribution and nitrate transport • Propose potential pollution patterns of nitrate distribution in the coastal aquifer • Identify anthropogenic input mainly responsible for increasing groundwater salinity

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

Energy Technology Data Exchange (ETDEWEB)

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

2015-12-15

transported for tens of years, through the complex carbonate aquifer matrix and the successive inputs of nitrogen from various sources. - Highlights: • Examine high nitrate contents in the coastal carbonate aquifer of northeast China • Estimate renewal rates and mean residence times of groundwater in coastal aquifers • Evaluate the relation between groundwater age distribution and nitrate transport • Propose potential pollution patterns of nitrate distribution in the coastal aquifer • Identify anthropogenic input mainly responsible for increasing groundwater salinity.

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.)

Isotope studies on mechanisms of groundwater recharge to an alluvial aquifer in Gatton, Queensland, Australia

International Nuclear Information System (INIS)

Dharmasiri, J.K.; Morawska, L.

1997-01-01

Gatton is an important agricultural area for Queensland where about 40% of its vegetables needs are produced using groundwater as the main source. An alluvial Aquifer is located about 30m beneath the layers of alluvial sediments ranging from black soils of volcanic origin on top, layers of alluvial sands, clays and beds of sand and gravel. The leakage of creek flows has been considered to be the main source of recharge to this aquifer. A number of weirs have been built across the Lockyer and Laidley creeks to allow surface water to infiltrate through the beds when the creeks flow. Water levels in bores in a section located in the middle of the alluvial plain (Crowley Vale) have been declining for the last 20 years with little or no success in recharging from the creeks. Acute water shortages have been experienced in the Gatton area during the droughts of 1980-81, 1986-87 and 1994-97. Naturally occurring stable isotopes, 2 H, 18 0 and 13 C as well as radioisotopes 3 H and 14 C have been used to delineate sources of recharge and active recharge areas. Tritium tracing of soil moisture in the unsaturated soil was also used to determine direct infiltration rates

Hydrogeology, water quality, and saltwater intrusion in the Upper Floridan Aquifer in the offshore area near Hilton Head Island, South Carolina, and Tybee Island, Georgia, 1999-2002

Science.gov (United States)

Falls, W. Fred; Ransom, Camille; Landmeyer, James E.; Reuber, Eric J.; Edwards, Lucy E.

2005-01-01

-mile site, the chloride concentration in the Upper Floridan borehole-water sample and the pore-water samples from the Oligocene and Eocene strata support the conclusion of no noticeable modern saltwater intrusion in the Upper Floridan aquifer. The chloride concentration of 370 milligrams per liter in the borehole-water sample at the 7-mile site from the Upper Floridan aquifer at 78 to 135 feet below North American Vertical Datum of 1988 is considerably higher than the chloride concentration of 25 milligrams per liter measured at the 10-mile site. The higher concentration probably is the result of downward leakage of saltwater through the confining unit at the 7-mile site or could reflect downward leakage of saltwater through an even thinner layer of the upper confining unit beneath the paleochannel to the northeast and lateral movement (encroachment) from the paleochannel to the 7-mile site. Carbon-14 concentrations at both sites, however, are low and indicate that most of the water is relict fresh ground water. The hydrogeology at the 15-mile site includes 17 feet of the upper confining unit. The chloride concentration in the Upper Floridan aquifer is 6,800 milligrams per liter. The setting for the Upper Floridan aquifer beneath the 15-mile site is interpreted as a transitional mixing zone between relict freshwater and relict saltwater. At the Calibogue site, 35 feet of fine-grained paleochannel-fill sediments overlies the Oligocene strata of the Upper Floridan aquifer. The vertical hydraulic conductivity of the paleochannel fill at this site is similar to the upper confining unit and effectively replaces the missing upper confining unit. Chloride concentrations and low carbon-14 and tritium concentrations in borehole water from the Upper Floridan aquifer, and low chloride concentrations in pore water from the upper confining unit indicate relict freshwater confined in the Upper Floridan aquifer at the Calibogue site. The coarse-grained paleochannel-f

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

Integrated approach for demarcating subsurface pollution and saline water intrusion zones in SIPCOT area: a case study from Cuddalore in Southern India.

Science.gov (United States)

Sankaran, S; Sonkamble, S; Krishnakumar, K; Mondal, N C

2012-08-01

This paper deals with a systematic hydrogeological, geophysical, and hydrochemical investigations carried out in SIPCOT area in Southern India to demarcate groundwater pollution and saline intrusion through Uppanar River, which flows parallel to sea coast with high salinity (average TDS 28, 870 mg/l) due to back waters as well as discharge of industrial and domestic effluents. Hydrogeological and geophysical investigations comprising topographic survey, self-potential, multi-electrode resistivity imaging, and water quality monitoring were found the extent of saline water intrusion in the south and pockets of subsurface pollution in the north of the study area. Since the area is beset with highly permeable unconfined quaternary alluvium forming potential aquifer at shallow depth, long-term excessive pumping and influence of the River have led to lowering of the water table and degradation of water quality through increased salinity there by generating reversal of hydraulic gradient in the south. The improper management of industrial wastes and left over chemicals by closed industries has led surface and subsurface pollution in the north of the study area.

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)

Geochemical evolution processes and water-quality observations based on results of the National Water-Quality Assessment Program in the San Antonio segment of the Edwards aquifer, 1996-2006

Science.gov (United States)

Musgrove, MaryLynn; Fahlquist, Lynne; Houston, Natalie A.; Lindgren, Richard J.; Ging, Patricia B.

2010-01-01

increase along flow paths; results for samples of Edwards aquifer groundwater show an increase from shallow/urban unconfined, to unconfined, to confined groundwater categories. These differences are consistent with longer residence times and greater extents of water-rock interaction controlling fluid compositions as groundwater evolves from shallow unconfined groundwater to deeper confined groundwater. Results for stable isotopes of hydrogen and oxygen indicate specific geochemical processes affect some groundwater samples, including mixing with downdip saline water, mixing with recent recharge associated with tropical cyclonic storms, or mixing with recharge water than has undergone evaporation. The composition of surface water recharging the aquifer, as well as mixing with downdip water from the Trinity aquifer or the saline zone, also might affect water quality. A time-series record (1938-2006) of discharge at Comal Springs, one of the major aquifer discharge points, indicates an upward trend for nitrate and chloride concentrations, which likely reflects anthropogenic activities. A small number of organic contaminants were routinely or frequently detected in Edwards aquifer groundwater samples. These were the pesticides atrazine, its degradate deethylatrazine, and simazine; the drinking-water disinfection byproduct chloroform; and the solvent tetrachloroethene. Detection of these contaminants was most frequent in samples of the shallow/urban unconfined groundwater category and least frequent in samples of the unconfined groundwater category. Results indicate that the shallow/urban unconfined part of the aquifer is most affected by anthropogenic contaminants and the unconfined part of the aquifer is the least affected. The high frequency of detection for these anthropogenic contaminants aquifer-wide and in samples of deep, confined groundwater indicates that the entire aquifer is susceptible to water-quality changes as a result of anthropogenic activities. L

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...

Development of a sharp interface model that simulates coastal aquifer flow with the coupled use of GIS

Science.gov (United States)

Gemitzi, Alexandra; Tolikas, Demetrios

A simulation program, which works seamlessly with GIS and simulates flows in coastal aquifers, is presented in the present paper. The model is based on the Galerkin finite element discretization scheme and it simulates both steady and transient freshwater and saltwater flow, assuming that the two fluids are separated by a sharp interface. The model has been verified in simple cases where analytical solutions exist. The simulation program works as a tool of the GIS program, which is the main database that stores and manages all the necessary data. The combined use of the simulation and the GIS program forms an integrated management tool offering a simpler way of simulating and studying saline intrusion in coastal aquifers. Application of the model to the Yermasogia aquifer illustrates the coupled use of modeling and GIS techniques for the examination of regional coastal aquifer systems. Pour étudier un système aquifère côtier, nous avons développé un modèle aux éléments finis en quasi 3-D qui simule les écoulements d'eau douce et d'eau salée en régime aussi bien permanent que transitoire. Les équations qui les régissent sont discrétisées par un schéma de discrétisation de Garlekin aux éléments finis. Le modèle a été vérifié dans des cas simples où il existe des solutions analytiques. Toutes les données nécessaires sont introduites et gérées grâce à un logiciel de gestion de SIG. Le programme de simulation est utilisé comme un outil du logiciel de SIG, constituant ainsi un outil de gestion intégrée dont le but est de simuler et d'étudier l'intrusion saline dans les aquifères côtiers. L'application du modèle à l'aquifère de Yermasogia illustre l'utilisation couplée de la modélisation et des techniques de SIG pour l'étude des systèmes aquifères côtiers régionaux. Se ha desarrollado un modelo casi tridimensional de elementos finitos para simular el flujo de agua dulce y salada, tanto en régimen estacionario como en

Satellite data analysis for identification of groundwater salinization effects on coastal forest for monitoring purposes

Directory of Open Access Journals (Sweden)

M. Barbarella

2015-05-01

Full Text Available In the phreatic aquifer below the San Vitale pinewood (Ravenna, Italy, natural and anthropogenic land subsidence, the low topography and the artificial drainage system have led to widespread saltwater intrusion. Since changes in the groundwater concentration induce variations in the vegetation properties, recognizable by different spectral bands, a comparison between satellite images, ASTER and Worldview-2, was made using the NDVI. The aim was to identify the portions of pinewood affected by salinization through a procedure that could reduce the expensive and time consuming ground monitoring campaigns. Moreover, the Worldview-2 high resolutions were used to investigate the Thermophilic Deciduous Forest (TDF spectral behaviour without the influence of the allochthonous Pinus pinea species that is scattered throughout the pinewood. The NDVI, calculated with traditional bands, identified the same stressed areas using both satellite data. Instead, the new Red-Edge band of the Worldview-2 image allowed a greater correlation between NDVI and groundwater salinity.

Occurrence and geochemical behavior of arsenic in a coastal aquifer-aquitard system of the Pearl River Delta, China

Energy Technology Data Exchange (ETDEWEB)

Wang, Ya [Department of Earth Sciences, The University of Hong Kong, Hong Kong (China); Jiao, Jiu Jimmy, E-mail: jjiao@hku.hk [Department of Earth Sciences, The University of Hong Kong, Hong Kong (China); Cherry, John A. [School of Engineering, University of Guelph, Guelph, ON, Canada N1G 2W1 (Canada)

2012-06-15

Elevated concentrations of arsenic, up to 161 {mu}g/L, have been identified in groundwater samples from the confined basal aquifer underlying the aquitard of the Pearl River Delta (PRD). Both aquatic arsenic in pore water and solid arsenic in the sediments in the basal aquifer and aquitard were identified. Arsenic speciation of groundwater in the basal aquifer was elucidated on a pH-Eh diagram. In the PRD, arsenic is enriched in groundwater having both low and high salinity, and arsenic enriched groundwater is devoid of dissolved oxygen, has negative Eh values, is slightly alkaline, and has abnormally high concentrations of ammonium and dissolved organic carbon, but low concentrations of nitrate and nitrite. Results of geochemical and hydrochemical analyses and sequential extraction analysis suggest that reductive dissolution of iron oxyhydroxide could be one of the important processes that mobilized solid arsenic. We speculate that mineralization of sedimentary organic matter could also contribute to aquatic arsenic. Scanning electron microscope analysis confirms that abundant authigenic pyrite is present in the sediments. Sulphate derived from paleo-seawater served as the important sulfur source for authigenic pyrite formation. Co-precipitation of arsenic with authigenic pyrite significantly controlled concentrations of aquatic arsenic in the coastal aquifer-aquitard system. - Highlights: Black-Right-Pointing-Pointer Coastal aquifer and aquitard are treated as an integrate system. Black-Right-Pointing-Pointer Both aquatic arsenic and solid arsenic are observed. Black-Right-Pointing-Pointer Aquatic arsenic is derived from reductive dissolution of iron oxyhydroxide. Black-Right-Pointing-Pointer Aquatic arsenic can also derived from mineralization of sedimentary organic matter. Black-Right-Pointing-Pointer Co-precipitation of arsenic with authigenic pyrite is significant in such a system.

InSAR detection of aquifer recovery: Case studies of Koehn Lake (central California) and Lone Tree Gold Mine (Basin and Range)

Science.gov (United States)

Wdowinski, S.; Greene, F.; Amelung, F.

2013-12-01

Anthropogenic intervention in groundwater flow and aquifer storage often results in vertical movements of Earth's surface, which are well detected by InSAR observations. Most anthropogenic intervention occurs due to groundwater extraction for both agriculture and human consumption and results in land subsidence. However in some cases, ending anthropogenic intervention can lead to aquifer recovery and, consequently, surface uplift. In this study we present two such cases of aquifer recovery. The first case is the aquifer beneath Koehn Lake in Central California, which was overused to meet agricultural demands until the 1990's. The second case is the Lone Tree Gold Mine in Nevada that during active mining in the 1991-2006 groundwater pumping disrupted the aquifer and cause subsidence. But after mining ceased, groundwater flow was recovered and resulted in uplift. In both cases we studied the surface uplift using InSAR time series observations. We conduct an ERS and Envisat InSAR survey over Koehn Lake in California and Lone Tree Gold Mine in Nevada between 1992 and 2010. We followed the SBAS algorithm to generate a time-series of ground displacements and average velocities of pixels, which remain coherent through time in the SAR dataset. A total of 100 and 80 combined ERS and Envisat SAR dates are inverted for Koehn Lake and Lone Tree Gold Mine respectively. Results for the Koehn Lake area indicate a rapid uplift of about 3.5 mm/yr between 1992-2000 and a slower uplift rate of 1.6 mm/yr between 2000-2004, suggesting a decrease in the recovery process. The observed uplift correlates well with groundwater level increase in the Koehn Lake area. Results for the Lone Tree Gold Mine show a constant subsidence (~ 1 cm/yr) due to groundwater extraction between 1992-2006, but uplift of ~1 cm/yr since the beginning of 2007. In both case studies, InSAR observations reveal that the aquifer recovery is accompanied by surface uplift. We plan to use the InSAR observations and the

Hidrogeoquímica en el acuífero costero del eje bananero de Urabá Hydrogeochemistry in the coastal aquifer of the Uraba region

Directory of Open Access Journals (Sweden)

Vanesa Paredes Zúñiga

2010-07-01

Full Text Available Las técnicas hidrogeoquímicas constituyen una herramienta complementaria a la hidrogeología dado que permiten responder los interrogantes que se presentan en sistemas complejos, como es el caso de los acuíferos costeros, donde la salinidad normalmente asociada a procesos de intrusión salina puede obedecer también a la conjunción con otros aspectos hidroclimatológicos e hidrodinámicos. Con la aplicación de la hidrogeoquímica y las relaciones iónicasse evidencia que los procesos de salinización presentes en el acuífero costero del Eje Bananero de Urabá podrían estar ligados a la interacción agua-roca, a mezclas con aguas que se salinizaron como resultado de procesos de transgresión-regresión antiguos en la zona de estudio. Este artículo resume los resultados del proyecto de investigación y la aplicación de la hidrogeoquímica y relaciones iónicas como metodología válida para determinar los diferentes procesos de salinización de las aguas de las zonas litorales.Hydrogeochemical techniques provide a complementary tool to hydrogeology as they provide certainty as to the questions related to complex systems, as is the case of coastal aquifers, in which salinity, usually associated to saline intrusion processes, may result from the fusion with other hydroclimatologic and hydrodynamic aspects. With the application of hydrogeochemistry and ionic relations, it has been evidenced that salinization processes in the coastal aquifer of Urabá Banana Axis could be linked to water-rock interaction, to mixtures with waters which salinized as a result of old transgression-regression processes in the zone under study. This article summarizes the results of the research project, the application of hydrogeochemistry, and ionic relations as a valid methodology to determine the different salinization processes of coastal areas.

Geophysical, geochemical and hydrological analyses of water-resource vulnerability to salinization: case of the Uburu-Okposi salt lakes and environs, southeast Nigeria

Science.gov (United States)

Ukpai, S. N.; Okogbue, C. O.

2017-11-01

Until this study, the location and depth of the saline units in Uburu-Okposi salt lake areas and environs have been unknown. This study aimed at delineating the saline lithofacies and dispersal configurations to water bodies, using electrical geophysical methods such as constant separation traversing (CST) and vertical electrical sounding (VES). Results showed weathered zones that represent aquifers mostly at the fourth geoelectric layer: between upper layered aquitards and underlying aquitards at depths 30-140 m. Lateral distribution of resistivity variance was defined by the CST, whereas the VES tool, targeted at low-resistivity zones, detected isolated saline units with less than 10 ohm-m at depths generally >78 m. The saline lithofacies were suspected to link freshwater zones via shear zones, which steer saline water towards the salt lakes and influence the vulnerability of groundwater to salinization. The level of salinization was verified by water sampling and analysis, and results showed general alkaline water type with a mean pH of 7.66. Water pollution was indicated: mean total dissolved solids (TDS) 550 mg/l, electrical conductivity (EC) 510 μS/cm, salinity 1.1‰, Cl- 200 mg/l, N03 -35.5 mg/l, Na+ 19.6 mg/l and Ca2+ 79.3 mg/l. The salinity is controlled by NaCl salt, as deduced from correlation analysis using the software package Statistical Product for Service Solutions (SPSS). Generally, concentrations of dissolved ions in the water of the area are enhanced via mechanisms such as evaporation, dissociation of salts, precipitation run off and leaching of dissolved rock minerals.

Monitoring and Modelling of Salinity Behaviour in Drinking Water Ponds in Southern Bangladesh

Science.gov (United States)

Hoque, M. A.; Williams, A.; Mathewson, E.; Rahman, A. K. M. M.; Ahmed, K. M.; Scheelbeek, P. F. D.; Vineis, P.; Butler, A. P.

2015-12-01

Drinking water in southern Bangladesh is provided by a variety of sources including constructed storage ponds, seasonal rainwater and, ubiquitously saline, shallow groundwater. The ponds, the communal reservoirs for harvested rainwater, also tend to be saline, some as high as 2 g/l. Drinking water salinity has several health impacts including high blood pressure associated major risk factor for several cardio-vascular diseases. Two representative drinking water ponds in Dacope Upazila of Khulna District in southwest Bangladesh were monitored over two years for rainfall, evaporation, pond and groundwater level, abstraction, and solute concentration, to better understand the controls on drinking water salinity. Water level monitoring at both ponds shows groundwater levels predominantly below the pond level throughout the year implying a downward gradient. The grain size analysis of the underlying sediments gives an estimated hydraulic conductivity of 3E-8 m/s allowing limited seepage loss. Water balance modelling indicates that the seepage has a relatively minor effect on the pond level and that the bulk of the losses come from the combination of evaporation and abstraction particularly in dry season when precipitation, the only inflow to the pond, is close to zero. Seasonal variation in salinity (electrical conductivities, EC, ranged between 1500 to 3000 μS/cm) has been observed, and are primarily due to dilution from rainfall and concentration from evaporation, except on one occasion when EC reached 16,000 μS/cm due to a breach in the pond levee. This event was analogous to the episodic inundation that occurs from tropical cyclone storm surges and appears to indicate that such events are important for explaining the widespread salinisation of surface water and shallow groundwater bodies in coastal areas. A variety of adaptations (either from practical protection measures) or novel alternative drinking sources (such as aquifer storage and recovery) can be applied

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...

Depth variations of P-wave azimuthal anisotropy beneath East Asia

Science.gov (United States)

Wei, W.; Zhao, D.; Xu, J.

2017-12-01

We present a new P-wave anisotropic tomographic model beneath East Asia by inverting a total of 1,488,531 P wave arrival-time data recorded by the regional seismic networks in East Asia and temporary seismic arrays deployed on the Tibetan Plateau. Our results provide important new insights into the subducting Indian, Pacific and Philippine Sea plates and mantle dynamics in East Asia. Our tomographic images show that the northern limit of the subducting Indian plate has reached the Jinsha River suture in eastern Tibet. A striking variation of P-wave azimuthal anisotropy is revealed in the Indian lithosphere: the fast velocity direction (FVD) is NE-SW beneath the Indian continent, whereas the FVD is arc parallel beneath the Himalaya and Tibetan Plateau, which may reflect re-orientation of minerals due to lithospheric extension, in response to the India-Eurasia collision. The FVD in the subducting Philippine Sea plate beneath the Ryukyu arc is NE-SW(trench parallel), which is consistent with the spreading direction of the West Philippine Basin during its initial opening stage, suggesting that it may reflect the fossil anisotropy. A circular pattern of FVDs is revealed around the Philippine Sea slab beneath SE China. We suggest that it reflects asthenospheric strain caused by toroidal mantle flow around the edge of the subducting slab. We find a striking variation of the FVD with depth in the subducting Pacific slab beneath the Northeast Japan arc. It may be caused by slab dehydration that changed elastic properties of the slab with depth. The FVD in the mantle wedge beneath the Northeast Japan and Ryukyu arcs is trench normal, which reflects subduction-induced convection. Beneath the Kuril and Izu-Bonin arcs where oblique subduction occurs, the FVD in the mantle wedge is nearly normal to the moving direction of the downgoing Pacific plate, suggesting that the oblique subduction together with the complex slab morphology have disturbed the mantle flow.

Modelling the effects of tides and storm surges on coastal aquifers using a coupled surface-subsurface approach.

Science.gov (United States)

Yang, Jie; Graf, Thomas; Herold, Maria; Ptak, Thomas

2013-06-01

Coastal aquifers are complex hydrologic systems because many physical processes interact: (i) variably saturated flow, (ii) spatial-temporal fluid density variations, (iii) tidal fluctuations, (iv) storm surges overtopping dykes, and (v) surface runoff of storm water. The HydroGeoSphere model is used to numerically simulate coastal flow dynamics, assuming a fully coupled surface-subsurface approach, accounting for all processes listed above. The diffusive wave approximation of the St. Venant equation is used to describe surface flow. Surface flow and salt transport are fully coupled with subsurficial variably saturated, variable-density flow and salt transport through mathematical terms that represent exchange of fluid mass and solute mass, respectively. Tides and storm surges induce a time-variant head that is applied to nodes of the surface domain. The approach is applied to real cases of tide and storm surge events. Tide simulation results confirm the existence of a recirculating zone, forming beneath the upper part of the intertidal zone. By monitoring the exchange fluid flux rates through the beach, it was found that the major inflow to the aquifer takes place at the upper part of the intertidal zone, which explains the formation of the recirculating zone. The recirculating zone is forming particularly during rising tide. Results from a storm surge simulation show that plume fingers develop below the flooded land surface. Natural remediation by seaward flowing freshwater is relatively slow, such that reducing the salt concentration in the aquifer down to drinking water standards takes up to 10 years. Copyright © 2013 Elsevier B.V. All rights reserved.

Assessment of managed aquifer recharge at Sand Hollow Reservoir, Washington County, Utah, updated to conditions in 2012

Science.gov (United States)

Marston, Thomas M.; Heilweil, Victor M.

2013-01-01

Sand Hollow Reservoir in Washington County, Utah, was completed in March 2002 and is operated primarily for managed aquifer recharge by the Washington County Water Conservancy District. From 2002 through 2011, surface-water diversions of about 199,000 acre-feet to Sand Hollow Reservoir have allowed the reservoir to remain nearly full since 2006. Groundwater levels in monitoring wells near the reservoir rose through 2006 and have fluctuated more recently because of variations in reservoir altitude and nearby pumping from production wells. Between 2004 and 2011, a total of about 19,000 acre-feet of groundwater was withdrawn by these wells for municipal supply. In addition, a total of about 21,000 acre-feet of shallow seepage was captured by French drains adjacent to the North and West Dams and used for municipal supply, irrigation, or returned to the reservoir. From 2002 through 2011, about 106,000 acre-feet of water seeped beneath the reservoir to recharge the underlying Navajo Sandstone aquifer. Water quality was sampled at various monitoring wells in Sand Hollow to evaluate the timing and location of reservoir recharge as it moved through the aquifer. Tracers of reservoir recharge include major and minor dissolved inorganic ions, tritium, dissolved organic carbon, chlorofluorocarbons, sulfur hexafluoride, and noble gases. By 2012, this recharge arrived at four monitoring wells located within about 1,000 feet of the reservoir. Changing geochemical conditions at five other monitoring wells could indicate other processes, such as changing groundwater levels and mobilization of vadose-zone salts, rather than arrival of reservoir recharge.

Hydrogeologic framework and hydrologic conditions of the Piney Point aquifer in Virginia

Science.gov (United States)

McFarland, E. Randolph

2017-06-07

The Piney Point aquifer in Virginia is newly described and delineated as being composed of six geologic units, in a study conducted by the U.S. Geological Survey in cooperation with the Virginia Department of Environmental Quality (VA DEQ). The eastward-dipping geologic units include, in stratigraphically ascending order, thesand of the Nanjemoy Formation Woodstock Member,interbedded limestone and sand of the Piney Point Formation,silty and clayey sand of the Gosport Formation equivalent sediments,silty sand of the Oligocene-age sediments,silty fine-grained sand of the Old Church Formation, andsilty sand of the Calvert Formation, Newport News unit and basal Plum Point Member.Identification of geologic units is based on typical sediment lithologies of geologic formations. Fine-grained sediments that compose confining units positioned immediately above and below the Piney Point aquifer are also described.The Piney Point aquifer is one of several confined aquifers within the Virginia Coastal Plain and includes a highly porous and solution-channeled indurated limestone within the Piney Point Formation from which withdrawals are made. The limestone is relatively continuous laterally across central parts of the Northern Neck, Middle Peninsula, and York-James Peninsula. Other geologic units are of variable extent. The configurations of most of the geologic units are further affected by newly identified faults that are aligned radially from the Chesapeake Bay impact crater and create constrictions or barriers to groundwater flow. Some geologic units are also truncated beneath the lower Rappahannock River by a resurge channel associated with the impact crater.Groundwater withdrawals from the Piney Point aquifer increased from approximately 1 million gallons per day (Mgal/d) during 1900 to 7.35 Mgal/d during 2004. As a result, a water-level cone of depression in James City and northern York Counties was estimated to be as low as 70 feet (ft) below the National Geodetic

Estimation of the recharge area contributing water to a pumped well in a glacial-drift, river-valley aquifer

Science.gov (United States)

Morrissey, Daniel J.

1989-01-01

degree of well penetration. Analytical methods proved easiest to apply but gave results that are considered to be less accurate than those obtainable by means of numerical-model analysis. Numerical models have the capability to more closely reflect the variable geohydrologic conditions typical of glacial-drift valley aquifers. For average conditions in the hypothetical aquifer, the analytical method predicts a contributing area limited to the well side of the river because a constant-head boundary simulated by image wells is used in the analytical model. For typical glacial-drift, river-valley aquifers, this simulation is unrealistic because drawdowns, caused by a pumping well, and the contributing area of the well can extend beneath and beyond a river or stream. A wide range of hydrologic conditions was simulated by using the two-dimensional numerical model. The resulting contributing area for a well pumped at 1.0 million gallons per day--a common pumping rate--ranged from about 0.9 to 1.8 square miles. Model analyses also show that the contributing area of pumped wells may be expected to extend to the opposite side of the river and to include significant areas of till uplands adjacent to the aquifer on both sides of the valley. Simulations done with the three-dimensional model allow a full three-dimensional delineation of the zone of contribution for a pumped well. For the relatively thin (100 feet or less) unconfined aquifers considered in this analysis, the three-dimensional model showed that the zone of contribution extended throughout the entire saturated thickness of aquifer; therefore, the two-dimensional simulations were considered adequate for delineating contributing areas in this particular hydrologic setting. For thicker aquifers, especially those having partially penetrating wells, three-dimensional models are preferable. Values for several of the factors that affect the size and shape of contributing recharge areas cannot be det

Stable groundwater quality in deep aquifers of Southern Bangladesh: the case against sustainable abstraction.

Science.gov (United States)

Ravenscroft, P; McArthur, J M; Hoque, M A

2013-06-01

In forty six wells >150 m deep, from across the arsenic-polluted area of south-central Bangladesh, groundwater composition remained unchanged between 1998 and 2011. No evidence of deteriorating water quality was found in terms of arsenic, iron, manganese, boron, barium or salinity over this period of 13 years. These deep tubewells have achieved operating lives of more than 20 years with minimal institutional support. These findings confirm that tubewells tapping the deep aquifers in the Bengal Basin provide a safe, popular, and economic, means of arsenic mitigation and are likely to do so for decades to come. Nevertheless, concerns remain about the sustainability of a resource that could serve as a source of As-safe water to mitigate As-pollution in shallower aquifers in an area where tens of millions of people are exposed to dangerous levels of arsenic in well water. The conjunction of the stable composition in deep groundwater and the severe adverse health effects of arsenic in shallow groundwater lead us to challenge the notion that strong sustainability principles should be applied to the management of deep aquifer abstraction in Bangladesh is, the notion that the deep groundwater resource should be preserved for future generations by protecting it from adverse impacts, probably of a minor nature, that could occur after a long time and might not happen at all. Instead, we advocate an ethical approach to development of the deep aquifer, based on adaptive abstraction management, which allows possibly unsustainable exploitation now in order to alleviate crippling disease and death from arsenic today while also benefiting future generations by improving the health, education and economy of living children. Copyright © 2013 Elsevier B.V. All rights reserved.

Environmental isotope application to investigate the hydrogeological aquifers of Yarmouk basin SW of Syria

International Nuclear Information System (INIS)

Al-Charideh, A.

2002-01-01

Environmental isotopic variations have been used to investigate the source of recharge and age in the basaltic and deep limestone aquifers system in the Yarmouk basin, SW of Syria. Isotopic results show that recharge of basaltic aquifer is directly related to infiltration of rainwater from high and transitional zones. However, the homogeneity noted of stable and radioactive isotopes values (δ 18 O= -5.58± 0.25%, 14 C=46.2± 4.45 % pmc) in Laja plateau and central zone, confirm the mechanism of common recharge and critical role of this plateau in absorbing great amount of precipitation. In addition these values indicate, to a high rate mixing taking place in this plateau and the central zone. In the Kahiel area, the groundwater is of recent age as shown from the high values of 14 C activity ( 14 C= 66.3 ± 5.3 % pcm) accompanied by enriched 18 O (δ 18 O=-4.7±0.22 %). The recharge of groundwater is related to the leakage of water from dams and drainage network. The tectonic setting in this area constitutes an additional factor in increasing this recharge. Netpath model was used to determine the age of groundwater. the age of groundwater in the basaltic aquifer is generally modern and reaches 2000 y BP in discharge area. Preliminary conclusion of deep limestone aquifer, indicate that its groundwater occur under high piezometric pressure. The salinity is less than 1g/L and the temperature water varied between 35 to 45 degreed centigrade. The low 14 C activities in deep groundwater suggest pleistocene and holocene recharge, although their stable isotopes values indicate recharge by modern meteoric precipitation. The corrected age of this groundwater determined by Netpath model indicate that this age fall between recent water in recharge area and 20 Ky BP. (author)

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).

Transboundary geophysical mapping of geological elements and salinity distribution critical for the assessment of future sea water intrusion in response to sea level rise

Directory of Open Access Journals (Sweden)

F. Jørgensen

2012-07-01

Full Text Available Geophysical techniques are increasingly being used as tools for characterising the subsurface, and they are generally required to develop subsurface models that properly delineate the distribution of aquifers and aquitards, salt/freshwater interfaces, and geological structures that affect groundwater flow. In a study area covering 730 km² across the border between Germany and Denmark, a combination of an airborne electromagnetic survey (performed with the SkyTEM system, a high-resolution seismic survey and borehole logging has been used in an integrated mapping of important geological, physical and chemical features of the subsurface. The spacing between flight lines is 200–250 m which gives a total of about 3200 line km. About 38 km of seismic lines have been collected. Faults bordering a graben structure, buried tunnel valleys, glaciotectonic thrust complexes, marine clay units, and sand aquifers are all examples of geological structures mapped by the geophysical data that control groundwater flow and to some extent hydrochemistry. Additionally, the data provide an excellent picture of the salinity distribution in the area and thus provide important information on the salt/freshwater boundary and the chemical status of groundwater. Although the westernmost part of the study area along the North Sea coast is saturated with saline water and the TEM data therefore are strongly influenced by the increased electrical conductivity there, buried valleys and other geological elements are still revealed. The mapped salinity distribution indicates preferential flow paths through and along specific geological structures within the area. The effects of a future sea level rise on the groundwater system and groundwater chemistry are discussed with special emphasis on the importance of knowing the existence, distribution and geometry of the mapped geological elements, and their control on the groundwater salinity distribution is assessed.

Impact of groundwater levels on evaporation and water-vapor fluxes in highly saline soils

Science.gov (United States)

Munoz, J. F.; Hernández, M. F.; Braud, I.; Gironas, J. A.; Suarez, F. I.

2012-12-01

In aquifers of arid and hyper-arid zones, such as those occurring in the Chilean Andes high plateau, it is important to determine both the quantity and location of water discharges at the temporal scales of interest to close the basin's water budget and thus, to manage the water resource properly. In zones where shallow aquifers are the main source of water, overexploitation of the water resource changes the dynamics of water, heat and solute transport in the vadose zone. As aquifers are exploited, fluctuations in depth to groundwater are exacerbated. These fluctuations modify both soil structure and evaporation from the ground, which is typically the most important discharge from the water budget and is very difficult to estimate. Therefore, a correct quantification of evaporation from these soils is essential to improve the accuracy of the water balance estimation. The objective of this study was to investigate the evaporation processes and water-vapor fluxes in a soil column filled with a saline soil from the Salar del Huasco basin, Chile. Water content, electrical conductivity and temperature at different depths in the soil profile were monitored to determine the liquid and vapor fluxes within the soil column. The results showed that evaporation is negligible when the groundwater table is deeper than 1 m. For shallower groundwater levels, evaporation increases in an exponential fashion reaching a value of 3 mm/day when the groundwater table is near the surface of the ground. These evaporation rates are on the same order of magnitude than the field measurements, but slightly lower due to the controlled conditions maintained in the laboratory. Isothermal fluid fluxes were predominant over the non-isothermal fluid and water vapor fluxes. The net flux for all the phreatic levels tested in the laboratory showed different behaviors, with ascending or descending flows as a consequence of changes in water content and temperature distribution within the soil. It was

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

Deficit irrigation of a landscape halophyte for reuse of saline waste water in a desert city

Science.gov (United States)

Glenn, E.P.; Mckeon, C.; Gerhart, V.; Nagler, P.L.; Jordan, F.; Artiola, J.

2009-01-01

Saline waste waters from industrial and water treatment processes are an under-utilized resource in desert urban environments. Management practices to safely use these water sources are still in development. We used a deeprooted native halophyte, Atriplex lentiformis (quailbush), to absorb mildly saline effluent (1800 mg l-1 total dissolved solids, mainly sodium sulfate) from a water treatment plant in the desert community of Twentynine Palms, California. We developed a deficit irrigation strategy to avoid discharging water past the root zone to the aquifer. The plants were irrigated at about one-third the rate of reference evapotranspiration (ETo) calculated from meteorological data over five years and soil moisture levels were monitored to a soil depth of 4.7 m at monthly intervals with a neutron hydroprobe. The deficit irrigation schedule maintained the soil below field capacity throughout the study. Water was presented on a more or less constant schedule, so that the application rates were less than ETo in summer and equal to or slightly greater than ETo in winter, but the plants were able to consume water stored in the profile in winter to support summer ET. Sodium salts gradually increased in the soil profile over the study but sulfate levels remained low, due to formation of gypsum in the calcic soil. The high salt tolerance, deep roots, and drought tolerance of desert halophytes such as A. lentiformis lend these plants to use as deficit-irrigated landscape plants for disposal of effluents in urban setting when protection of the aquifer is important. ?? 2008 Elsevier B.V.

Groundwater-level trends and forecasts, and salinity trends, in the Azraq, Dead Sea, Hammad, Jordan Side Valleys, Yarmouk, and Zarqa groundwater basins, Jordan

Science.gov (United States)

Goode, Daniel J.; Senior, Lisa A.; Subah, Ali; Jaber, Ayman

2013-01-01

Changes in groundwater levels and salinity in six groundwater basins in Jordan were characterized by using linear trends fit to well-monitoring data collected from 1960 to early 2011. On the basis of data for 117 wells, groundwater levels in the six basins were declining, on average about -1 meter per year (m/yr), in 2010. The highest average rate of decline, -1.9 m/yr, occurred in the Jordan Side Valleys basin, and on average no decline occurred in the Hammad basin. The highest rate of decline for an individual well was -9 m/yr. Aquifer saturated thickness, a measure of water storage, was forecast for year 2030 by using linear extrapolation of the groundwater-level trend in 2010. From 30 to 40 percent of the saturated thickness, on average, was forecast to be depleted by 2030. Five percent of the wells evaluated were forecast to have zero saturated thickness by 2030. Electrical conductivity was used as a surrogate for salinity (total dissolved solids). Salinity trends in groundwater were much more variable and less linear than groundwater-level trends. The long-term linear salinity trend at most of the 205 wells evaluated was not increasing, although salinity trends are increasing in some areas. The salinity in about 58 percent of the wells in the Amman-Zarqa basin was substantially increasing, and the salinity in Hammad basin showed a long-term increasing trend. Salinity increases were not always observed in areas with groundwater-level declines. The highest rates of salinity increase were observed in regional discharge areas near groundwater pumping centers.

Geochemical evolution of groundwater salinity at basin scale: a case study from Datong basin, Northern China.

Science.gov (United States)

Wu, Ya; Wang, Yanxin

2014-05-01

A hydrogeochemical investigation using integrated methods of stable isotopes ((18)O, (2)H), (87)Sr/(86)Sr ratios, Cl/Br ratios, chloride-mass balance, mass balance and hydrogeochemical modeling was conducted to interpret the geochemical evolution of groundwater salinity in Datong basin, northern China. The δ(2)H, δ(18)O ratios in precipitation exhibited a local meteoric water line of δ(2)H = 6.4 δ(18)O -5 (R(2) = 0.94), while those in groundwater suggested their meteoric origin in a historically colder climatic regime with a speculated recharge rate of less than 20.5 mm overall per year, in addition to recharge from a component of deep residual ancient lake water enriched with Br. According to the Sr isotope binary mixing model, the mixing of recharges from the Shentou karst springs (24%), the western margins (11%) and the eastern margins (65%) accounts for the groundwater from the deep aquifers of the down-gradient parts in the central basin is a possible mixing mechanism. In Datong, hydrolysis of silicate minerals is the most important hydrogeochemical process responsible for groundwater chemistry, in addition to dissolution of carbonate and evaporites. In the recharge areas, silicate chemical weathering is typically at the bisiallitization stage, while that in the central basin is mostly at the monosiallitization stage with limited evidence of being in equilibrium with gibbsite. Na exchange with bound Ca, Mg prevails at basin scale, and intensifies with groundwater salinity, while Ca, Mg exchange with bound Na locally occurs in the east pluvial and alluvial plains. Although groundwater salinity increases with the progress of water-rock/sediment interactions along the flow path, as a result of carbonate solubility control and continuous evapotranspiration, Na-HCO3 and Na-Cl-SO4 types of water are usually characterized respectively in the deep and the shallow aquifers of an inland basin with a silicate terrain in an arid climatic regime.

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.

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.

A multi-method approach for groundwater resource assessment in coastal carbonate (karst) aquifers: the case study of Sierra Almijara (southern Spain)

Science.gov (United States)

Andreo, B.; Barberá, J. A.; Mudarra, M.; Marín, A. I.; García-Orellana, J.; Rodellas, V.; Pérez, I.

2018-02-01

Understanding the transference of water resources within hydrogeological systems, particularly in coastal aquifers, in which groundwater discharge may occur through multiple pathways (through springs, into rivers and streams, towards the sea, etc.), is crucial for sustainable groundwater use. This research aims to demonstrate the usefulness of the application of conventional recharge assessment methods coupled to isotopic techniques for accurately quantifying the hydrogeological balance and submarine groundwater discharge (SGD) from coastal carbonate aquifers. Sierra Almijara (Southern Spain), a carbonate aquifer formed of Triassic marbles, is considered as representative of Mediterranean coastal karst formations. The use of a multi-method approach has permitted the computation of a wide range of groundwater infiltration rates (17-60%) by means of direct application of hydrometeorological methods (Thornthwaite and Kessler) and spatially distributed information (modified APLIS method). A spatially weighted recharge rate of 42% results from the most coherent information on physiographic and hydrogeological characteristics of the studied system. Natural aquifer discharge and groundwater abstraction have been volumetrically quantified, based on flow and water-level data, while the relevance of SGD was estimated from the spatial analysis of salinity, 222Rn and the short-lived radium isotope 224Ra in coastal seawater. The total mean aquifer discharge (44.9-45.9 hm3 year-1) is in agreement with the average recharged groundwater (44.7 hm3 year-1), given that the system is volumetrically equilibrated during the study period. Besides the groundwater resources assessment, the methodological aspects of this research may be interesting for groundwater management and protection strategies in coastal areas, particularly karst environments.

Deformation in D″ Beneath North America From Anisotropy

Science.gov (United States)

Nowacki, A. J.; Wookey, J.; Kendall, J. M.

2009-12-01

The lowermost few hundred kilometres of the Earth's mantle—known as D″—form the boundary between it and the core below, control the Earth's convective system, and are the site of probable large thermochemical heterogeneity. Seismic observations of D″ show a strong heterogeneity in seismic wave velocity and significant seismic anisotropy (the variation of wave speed with direction) are present in many parts of the region. On the basis of continuous regions of fast shear velocity (VS) anomalies in global models, it is also proposed as the resting place of subducted slabs, notably the Farallon beneath North America. A phase change of MgSiO3-perovskite (pv) to a post-perovskite (ppv) structure at near-core-mantle boundary (CMB) conditions is a compelling mechanism to explain the seismic features of D″. An outstanding question is how this and other mineral phases may deform to produce anisotropy, with different mechanisms possible. With knowledge either of mantle flow or which slip system is responsible for causing deformation, we can potentially determine the other with observations of the resulting seismic anisotropy. We investigate the dynamics at the CMB beneath North America using differential shear wave splitting in S and ScS phases from earthquakes of magnitude MW>5.5 in South and Central America, Hawaii the Mid-Atlantic Ridge and East Pacific Rise. They are detected on ~500 stations in North America, giving ~700 measurements of anisotropy in D″. We achieve this by correcting for anisotropy in the upper mantle (UM) beneath both the source and receiver. The measurements cover three regions beneath western USA, the Yucatan peninsula and Florida. In each case, two different, crossing ray paths are used, so that the style of anisotropy can be constrained—a single azimuth cannot distinguish differing cases. Our results showing ~1% anisotropy dependent on azimuth are not consistent with transverse isotropy with a vertical symmetry axis (VTI) anywhere. The

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

Science.gov (United States)

Janardhanan, S.; Datta, B.

2011-12-01

saltwater intrusion are considered. The salinity levels resulting at strategic locations due to these pumping are predicted using the ensemble surrogates and are constrained to be within pre-specified levels. Different realizations of the concentration values are obtained from the ensemble predictions corresponding to each candidate solution of pumping. Reliability concept is incorporated as the percent of the total number of surrogate models which satisfy the imposed constraints. The methodology was applied to a realistic coastal aquifer system in Burdekin delta area in Australia. It was found that all optimal solutions corresponding to a reliability level of 0.99 satisfy all the constraints and as reducing reliability level decreases the constraint violation increases. Thus ensemble surrogate model based simulation-optimization was found to be useful in deriving multi-objective optimal pumping strategies for coastal aquifers under parameter uncertainty.

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....

Salinization and arsenic contamination of surface water in southwest Bangladesh.

Science.gov (United States)

Ayers, John C; George, Gregory; Fry, David; Benneyworth, Laura; Wilson, Carol; Auerbach, Leslie; Roy, Kushal; Karim, Md Rezaul; Akter, Farjana; Goodbred, Steven

2017-09-11

To identify the causes of salinization and arsenic contamination of surface water on an embanked island (i.e., polder) in the tidal delta plain of SW Bangladesh we collected and analyzed water samples in the dry (May) and wet (October) seasons in 2012-2013. Samples were collected from rice paddies (wet season), saltwater ponds used for brine shrimp aquaculture (dry season), freshwater ponds and tidal channels (both wet and dry season), and rainwater collectors. Continuous measurements of salinity from March 2012 to February 2013 show that tidal channel water increases from ~0.15 ppt in the wet season up to ~20 ppt in the dry season. On the polder, surface water exceeds the World Health Organization drinking water guideline of 10 μg As/L in 78% of shrimp ponds and 27% of rice paddies, raising concerns that produced shrimp and rice could have unsafe levels of As. Drinking water sources also often have unsafe As levels, with 83% of tubewell and 43% of freshwater pond samples having >10 μg As/L. Water compositions and field observations are consistent with shrimp pond water being sourced from tidal channels during the dry season, rather than the locally saline groundwater from tubewells. Irrigation water for rice paddies is also obtained from the tidal channels, but during the wet season when surface waters are fresh. Salts become concentrated in irrigation water through evaporation, with average salinity increasing from 0.43 ppt in the tidal channel source to 0.91 ppt in the rice paddies. Our observations suggest that the practice of seasonally alternating rice and shrimp farming in a field has a negligible effect on rice paddy water salinity. Also, shrimp ponds do not significantly affect the salinity of adjacent surface water bodies or subjacent groundwater because impermeable shallow surface deposits of silt and clay mostly isolate surface water bodies from each other and from the shallow groundwater aquifer. Bivariate plots of conservative element

Hydrogeology and water quality of the stratified-drift aquifer in the Pony Hollow Creek Valley, Tompkins County, New York

Science.gov (United States)

Bugliosi, Edward F.; Miller, Todd S.; Reynolds, Richard J.

2014-01-01

away from groundwater mounds that have formed beneath upland tributaries that lose water where they flow on alluvial fans on the margins of the valley. In some places, groundwater that would normally flow toward streams is intercepted by pumping wells. Surface-water samples were collected in 2001 at four sites including Carter, Pony Hollow (two sites), and Chafee Creeks, and from six wells throughout the aquifer. Calcium dominates the cation composition and bicarbonate dominates the anion composition in groundwater and surface-water samples and none of the common inorganic constituents collected exceeded any Federal or State water-quality standards. Groundwater samples were collected from six wells all completed in the unconfined sand and gravel aquifer. Concentrations of calcium and magnesium dominated the ionic composition of the groundwater in all wells sampled. Nitrate, orthophosphate, and trace metals were detected in all groundwater samples, but none were more than U.S. Environmental Protection Agency or New York State Department of Health regulatory limits.

On the Sources of Salinity in Groundwater under Plain Areas. Insights from {delta}{sup 18}O, {delta}{sup 2}H and Hydrochemistry in the Azul River Basin, Argentina

Energy Technology Data Exchange (ETDEWEB)

Zabala, M. E.; Varni, M.; Weinzettel, P. [Instituto de Hidrologia de llanuras, Azul (Argentina); Manzano, M. [Technical University of Cartagena (Spain)

2013-07-15

The Azul River basin, with some 6200 km{sup 2}, is located in the plains of Buenos Aires Province, Argentina. The Azul River flows along 160 km from the Tandilia Range, in the SW, to the Channel 11, in the NE. Average annual precipitation is 1005 mm (1988-2000); mean reference evapotranspiration is 1090 mm. The geology consists of Miocene to recent sediments, mostly sands and silts with some clay and calcrete layers, overlying crystalline rocks and marine sediments. The water table is shallow and groundwater in the aquifer upper 30 m displays an increasing salinity from SW to NE. The previous hypothesis to explain the salinity was infiltration of evapo-concentrated surface water, as the small soil slope in the northern basin (< 0.2%) induces rainfall accumulation in lowlands, where water evaporates prior to infiltration. But recent chemical and isotopic data reveal two salinity sources: evaporation of recent recharge water, and mixing with old saline groundwater of yet unknown origin. (author)

Soil property control of biogeochemical processes beneath two subtropical stormwater infiltration basins.

Science.gov (United States)

O'Reilly, Andrew M; Wanielista, Martin P; Chang, Ni-Bin; Harris, Willie G; Xuan, Zhemin

2012-01-01

Substantially different biogeochemical processes affecting nitrogen fate and transport were observed beneath two stormwater infiltration basins in north-central Florida. Differences are related to soil textural properties that deeply link hydroclimatic conditions with soil moisture variations in a humid, subtropical climate. During 2008, shallow groundwater beneath the basin with predominantly clayey soils (median, 41% silt+clay) exhibited decreases in dissolved oxygen from 3.8 to 0.1 mg L and decreases in nitrate nitrogen (NO-N) from 2.7 mg L to soils (median, 2% silt+clay), aerobic conditions persisted from 2007 through 2009 (dissolved oxygen, 5.0-7.8 mg L), resulting in NO-N of 1.3 to 3.3 mg L in shallow groundwater. Enrichment of δN and δO of NO combined with water chemistry data indicates denitrification beneath the clayey basin and relatively conservative NO transport beneath the sandy basin. Soil-extractable NO-N was significantly lower and the copper-containing nitrite reductase gene density was significantly higher beneath the clayey basin. Differences in moisture retention capacity between fine- and coarse-textured soils resulted in median volumetric gas-phase contents of 0.04 beneath the clayey basin and 0.19 beneath the sandy basin, inhibiting surface/subsurface oxygen exchange beneath the clayey basin. Results can inform development of soil amendments to maintain elevated moisture content in shallow soils of stormwater infiltration basins, which can be incorporated in improved best management practices to mitigate NO impacts. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

Elastic and Anelastic Structure Beneath Eurasia

National Research Council Canada - National Science Library

Ekstrom, Goran

1997-01-01

The primary objective of this work has been to map the variations of elastic mantle properties beneath Eurasia over horizontal length scales of approximately 1000-1500 kilometers and vertial length...

Electrical Resistivity Imaging and Hydrodynamic Modeling of Convective Fingering in a Sabkha Aquifer

Science.gov (United States)

Van Dam, Remke; Eustice, Brian; Hyndman, David; Wood, Warren; Simmons, Craig

2014-05-01

Free convection, or fluid motion driven by density differences, is an important groundwater flow mechanism that can enhance transport and mixing of heat and solutes in the subsurface. Various issues of environmental and societal relevance are exacerbated convective mixing; it has been studied in the context of dense contaminant plumes, nuclear waste disposal, greenhouse gas sequestration, the impacts of sea level rise and saline intrusion on drinking water resources. The basic theory behind convective flow in porous media is well understood, but important questions regarding this process in natural systems remain unanswered. Most previous research on this topic has focused on theory and modeling, with only limited attention to experimental studies and field measurements. The few published studies present single snapshots, making it difficult to quantify transient changes in these systems. Non-invasive electrical methods have the potential to exploit the relation between solute concentrations and electrical conductance of a fluid, and thereby estimate fluid salinity differences in time and space. We present the results of a two-year experimental study at a shallow sabkha aquifer in the United Arab Emirates, about 50 km southwest of the city of Abu Dhabi along the coast of the Arabian Gulf, that was designed to explore the transient nature of free convection. Electrical resistivity tomography (ERT) data documented the presence of convective fingers following a significant rainfall event. One year later, the complex fingering pattern had completely disappeared. This observation is supported by analysis of the aquifer solute budget as well as hydrodynamic modeling of the system. The transient dynamics of the gravitational instabilities in the modeling results are in agreement with the timing observed in the time-lapse ERT data. Our experimental observations and modeling are consistent with the hypothesis that the instabilities arose from a dense brine that infiltrated

Assessing hydraulic connections across a complex sequence of volcanic rocks - Analysis of U-20 WW multiple-well aquifer test, Pahute Mesa, Nevada National Security Site, Nevada

Science.gov (United States)

Garcia, C. Amanda; Fenelon, Joseph M.; Halford, Keith J.; Reiner, Steven R.; Laczniak, Randell J.

2011-01-01

Groundwater beneath Pahute Mesa flows through a complexly layered sequence of volcanic rock aquifers and confining units that have been faulted into distinct structural blocks. Hydraulic property estimates of rocks and structures in this flow system are necessary to assess radionuclide migration near underground nuclear testing areas. The U.S. Geological Survey (USGS) used a 12 month (October 1, 2008— October 1, 2009) intermittent pumping schedule of well U-20 WW and continuously monitored water levels in observation wells ER-20-6 #3, UE-20bh 1, and U-20bg as a multi-well aquifer test to evaluate hydraulic connections across structural blocks, bulk hydraulic properties of volcanic rocks, and the hydraulic significance of a major fault. Measured water levels were approximated using synthetic water levels generated from an analytical model. Synthetic water levels are a summation of environmental water-level fluctuations and a Theis (1935) transform of the pumping signal from flow rate to water-level change. Drawdown was estimated by summing residual differences between measured and synthetic water levels and the Theis-transformed pumping signal from April to September 2009. Drawdown estimates were used in a three‑dimensional numerical model to estimate hydraulic properties of distinct aquifers, confining units, and a major fault.