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Sample records for aquifer system california

  1. Characteristics of Southern California coastal aquifer systems

    USGS Publications Warehouse

    Edwards, B.D.; Hanson, R.T.; Reichard, E.G.; Johnson, T.A.

    2009-01-01

    Most groundwater produced within coastal Southern California occurs within three main types of siliciclastic basins: (1) deep (>600 m), elongate basins of the Transverse Ranges Physiographic Province, where basin axes and related fluvial systems strike parallel to tectonic structure, (2) deep (>6000 m), broad basins of the Los Angeles and Orange County coastal plains in the northern part of the Peninsular Ranges Physiographic Province, where fluvial systems cut across tectonic structure at high angles, and (3) shallow (75-350 m), relatively narrow fluvial valleys of the generally mountainous southern part of the Peninsular Ranges Physiographic Province in San Diego County. Groundwater pumped for agricultural, industrial, municipal, and private use from coastal aquifers within these basins increased with population growth since the mid-1850s. Despite a significant influx of imported water into the region in recent times, groundwater, although reduced as a component of total consumption, still constitutes a significant component of water supply. Historically, overdraft from the aquifers has caused land surface subsidence, flow between water basins with related migration of groundwater contaminants, as well as seawater intrusion into many shallow coastal aquifers. Although these effects have impacted water quality, most basins, particularly those with deeper aquifer systems, meet or exceed state and national primary and secondary drinking water standards. Municipalities, academicians, and local water and governmental agencies have studied the stratigraphy of these basins intensely since the early 1900s with the goals of understanding and better managing the important groundwater resource. Lack of a coordinated effort, due in part to jurisdictional issues, combined with the application of lithostratigraphic correlation techniques (based primarily on well cuttings coupled with limited borehole geophysics) have produced an often confusing, and occasionally conflicting

  2. Geohydrology and mathematical simulation of the Pajaro Valley aquifer system, Santa Cruz and Monterey counties, California

    USGS Publications Warehouse

    Johnson, M.J.; Londquist, C.J.; Laudon, Julie; Mitten, H.T.

    1988-01-01

    Groundwater development has resulted in lowered water levels and seawater intrusion in the Pajaro Valley, California. An investigation was undertaken to describe the geohydrology of the groundwater flow system and to evaluate the response of the system to pumping stresses by using a mathematical model. The aquifer system consists of three aquifers. The lower aquifer is in fluvial sequences of Quaternary Aromas Sand below interbedded clay layers. The middle aquifer is in upper fluvial and lower eolian sequence of Aromas Sand, and in overlying basal gravels in terrace deposits and alluvium. Weathered soil zones in the Aromas Sand, and clay layers in the terrace deposits and alluvium overlie the middle aquifer. The upper aquifer is actually many discontinuous water bearing zones in the Aromas Sand, terrace deposits, alluvium, and dune sand. The three aquifers are represented in the mathematical model by three model layers separated by two confining layers. Model-generated water budgets for the 11-year simulation period show that storage decreased by 23,000 acre-ft, mostly during the 1976-77 drought. The calibrated model can simulate, with acceptable accuracy, both semiannual and long-term trends of potentiometric heads in parts of the lower and middle layers. (USGS)

  3. Chemical and isotopic prediction of aquifer temperatures in the geothermal system at Long Valley, California

    USGS Publications Warehouse

    Fournier, R.O.; Sorey, M.L.; Mariner, R.H.; Truesdell, A.H.

    1979-01-01

    Temperatures of aquifers feeding thermal springs and wells in Long Valley, California, estimated using silica and Na-K-Ca geothermometers and warm spring mixing models, range from 160/dg to about 220??C. This information was used to construct a diagram showing enthalpy-chloride relations for the various thermal waters in the Long Valley region. The enthalpy-chloride information suggests that a 282 ?? 10??C aquifer with water containing about 375 mg chloride per kilogram of water is present somewhere deep in the system. That deep water would be related to ??? 220??C Casa Diablo water by mixing with cold water, and to Hot Creek water by first boiling with steam loss and then mixing with cold water. Oxygen and deuterium isotopic data are consistent with that interpretation. An aquifer at 282??C with 375 mg/kg chloride implies a convective heat flow in Long Valley of 6.6 ?? 107 cal/s. ?? 1979.

  4. Southern California Alluvial Basins Regional Aquifer-Systems analysis; a bibliography

    USGS Publications Warehouse

    Moyle, W.R.; Martin, Peter; Schluter, R.C.; Woolfenden, L.R.; Downing, Karen; Elliott, A.L.; Maltby, D.E.

    1986-01-01

    A bibliography for the Southern California Alluvial Basins Regional Aquifer-Systems Analysis includes references for about 3,500 publications related to the geohydrology of the 75,000 sq-mi region, which encompasses all of southern California except the Central Valley, the Channel Islands and the Pacific Ocean floor off southern California, and parts of adjacent states and Mexico. The report indexes the publications in six geographic categories and induces a list of sources of publications. Because of the large number of references in the bibliography, a system was developed for computer storage and retrieval. References can be retrieved by geographic location, author, or geohydrologic discipline and subject. The computer system allows for updating and addition of references. (USGS)

  5. Near-conservative behavior of 129Iodine in the Orange County Aquifer System, California

    SciTech Connect

    Schwer, K A; Santschi, P H; Moran, J E; Elmore, D

    2005-01-21

    Iodine is a biophilic element, with one stable isotope, {sup 127}I, and one long-lived radioisotope, {sup 129}I, which originates in the surface environment almost entirely from anthropogenic activities such as nuclear fuel reprocessing. Very few studies have evaluated the geochemical behavior of iodine isotopes in the subsurface. The concentrations of {sup 129}I and {sup 127}I were measured in wells fed by a series of artificial recharge ponds in the Forebay Area of the Orange County groundwater basin (California, USA) to evaluate their potential use as hydrological tracers. To substantiate interpretation of {sup 129}I and {sup 127}I concentration data, the aquifer system was evaluated using literature values of aquifer water mass age based on {sup 3}H/{sup 3}He, Xenon and {delta}{sup 18}O tracer data, as well as time-series data of Santa Ana River flow rates over the past decade. The aquifer data demonstrate the nearly conservative behavior of {sup 129}I, with {sup 129}I/{sup 127}I ratios likely reflecting variations in source functions as well as climatic conditions, and with inferred particle-water partition coefficients (K{sub d}) of 0.1 cm{sup 3} g{sup -1} or less.

  6. Geohydrology of deep-aquifer system monitoring-well site at Marina, Monterey County, California

    USGS Publications Warehouse

    Hanson, Randall T.; Everett, Rhett; Newhouse, Mark W.; Crawford, Steven M.; Pimentel, M. Isabel; Smith, Gregory A.

    2002-01-01

    In 2000, a deep-aquifer system monitoring-well site (DMW1) was completed at Marina, California to provide basic geologic and hydrologic information about the deep-aquifer system in the coastal region of the Salinas Valley. The monitoring-well site contains four wells in a single borehole; one completed from 930 to 950 feet below land surface (bls) in the Paso Robles Formation (DMW1-4); one 1,040 to 1,060 feet below land surface in the upper Purisima Formation (DMW1-3); one from 1,410 to 1,430 feet below land surface in the middle Purisima Formation (DMW1-2); and one from 1,820 to 1,860 feet below land surface in the lower Purisima Formation (DMW1-1). The monitoring site is installed between the coast and several deep-aquifer system supply wells in the Marina Coast Water District, and the completion depths are within the zones screened in those supply wells. Sediments below a depth of 955 feet at DMW1 are Pliocene age, whereas the sediments encountered at the water-supply wells are Pleistocene age at an equivalent depth. Water levels are below sea level in DMW1 and the Marina Water District deep-aquifer system supply wells, which indicate that the potential for seawater intrusion exists in the deep-aquifer system. If the aquifers at DMW1 are hydraulically connected with the submarine outcrops in Monterey Bay, then the water levels at the DMW1 site are 8 to 27 feet below the level necessary to prevent seawater intrusion. Numerous thick fine-grained interbeds and confining units in the aquifer systems retard the vertical movement of fresh and saline ground water between aquifers and restrict the movement of seawater to narrow water-bearing zones in the upper-aquifer system.Hydraulic testing of the DMW1 and the Marina Water District supply wells indicates that the tested zones within the deep-aquifer system are transmissive water-bearing units with hydraulic conductivities ranging from 2 to 14.5 feet per day. The hydraulic properties of the supply wells and monitoring

  7. Hydraulic and mechanical properties affecting ground-water flow and aquifer-system compaction, San Joaquin Valley, California

    USGS Publications Warehouse

    Sneed, Michelle

    2001-01-01

    This report summarizes hydraulic and mechanical properties affecting ground-water flow and aquifer-system compaction in the San Joaquin Valley, a broad alluviated intermontane structural trough that constitutes the southern two-thirds of the Central Valley of California. These values will be used to constrain a coupled ground-water flow and aquifer-system compaction model of the western San Joaquin Valley called WESTSIM. A main objective of the WESTSIM model is to evaluate potential future land subsidence that might occur under conditions in which deliveries of imported surface water for agricultural use are reduced and ground-water pumping is increased. Storage values generally are components of the total aquifer-system storage and include inelastic and elastic skeletal storage values of the aquifers and the aquitards that primarily govern the potential amount of land subsidence. Vertical hydraulic conductivity values generally are for discrete thicknesses of sediments, usually aquitards, that primarily govern the rate of land subsidence. The data were compiled from published sources and include results of aquifer tests, stress-strain analyses of borehole extensometer observations, laboratory consolidation tests, and calibrated models of aquifer-system compaction.

  8. A plan to study the aquifer system of the Central Valley of California

    USGS Publications Warehouse

    Bertoldi, Gilbert L.

    1979-01-01

    Unconsolidated Quaternary alluvial deposits comprise a large complex aquifer system in the Central Valley of California. Millions of acre-feet of water is pumped from the system annually to support a large and expanding agribusiness industry. Since the 1950's, water levels have been steadily declining in many areas of the valley and concern has been expressed about the ability of the entire ground-water system to support agribusiness at current levels, not to mention its ability to function at projected expansion levels. At current levels of ground-water use, an estimated 1.5 to 2 million acre-feet is withdrawn from storage each year; that is, 1.5 to 2 million acre-feet of water is pumped annually in excess of annual replenishment. The U.S. Geological Survey has initiated a 4-year study to develop geologic, hydrologic, and hydraulic information and to establish a valleywide ground-water data base that will be used to build computer models of the ground-water flow system. Subsequently, these models may be used to evaluate the system response to various ground-water management alternatives. This report describes current problems, objectives of the study, and outlines the general work to be accomplished in the study area. A bibliography of about 600 references is included. (Kosco-USGS)

  9. Aquifer-System Characterization by Integrating Data from the Subsurface and from Space, San Joaquin Valley, California, USA

    NASA Astrophysics Data System (ADS)

    Sneed, M.; Brandt, J. T.

    2014-12-01

    Extensive groundwater pumping from the aquifer system in the San Joaquin Valley, California, between 1926 and 1970 caused widespread aquifer-system compaction and resultant land subsidence that locally exceeded 8 m. The importation of surface water in the early 1970s resulted in decreased pumping, recovery of water levels, and a reduced rate of subsidence in some areas. Recently, land-use changes and reductions in surface-water availability have caused pumping to increase, water levels to decline, and subsidence to recur. Reduced freeboard and flow capacity of several Federal, State, and local canals have resulted from this subsidence. Vertical land-surface changes during 2005-14 in the San Joaquin Valley were determined by using space-based [Interferometric Synthetic Aperture Radar (InSAR) and Global Positioning System (GPS)] and subsurface (extensometer) data; groundwater-level and lithologic data were used to understand and estimate properties that partly control the stress/strain response of the aquifer system. Results of the InSAR analysis indicate that two areas covering about 7,200 km2 subsided 20-540 mm during 2008-10; GPS data indicate that these rates continued through 2014. Groundwater levels (stress) and vertical land-surface changes (strain) were used to estimate preconsolidation head and aquifer system storage coefficients. Integrating lithology into the analysis indicates that in some parts of the valley, the compaction occurred primarily within quickly-equilibrating fine-grained deposits in deeper parts of the aquifer system. In other parts of the valley, anomalously fine-grained alluvial-fan deposits underlie one of the most rapidly subsiding areas, indicating the shallow sediments may also contribute to total subsidence. This information helps improve hydrologic and aquifer-system compaction models, which in turn can be used to consider land subsidence as a constraint in evaluating water-resource management options.

  10. A combined radio- and stable-isotopic study of a California coastal aquifer system

    USGS Publications Warehouse

    Swarzenski, Peter W.; Baskaran, Mark; Rosenbauer, Robert J.; Edwards, Brian D.; Land, Michael

    2013-01-01

    Stable and radioactive tracers were utilized in concert to characterize geochemical processes in a complex coastal groundwater system and to provide constraints on the kinetics of rock/water interactions. Groundwater samples from wells within the Dominguez Gap region of Los Angeles County, California were analyzed for a suite of major cations (Na+, K+, Mg2+, Ca2+) and anions (Cl−, SO42−), silica, alkalinity, select trace elements (Ba, B, Sr), dissolved oxygen, stable isotopes of hydrogen (δD), oxygen (δ18O), dissolved inorganic carbon (δ13CDIC), and radioactive isotopes (3H, 222Rn and 223,224,226,228Ra). In the study area, groundwater may consist of a complex mixture of native groundwater, intruded seawater, non-native injected water, and oil-field brine water. In some wells, Cl− concentrations attained seawater-like values and in conjunction with isotopically heavier δ18O values, these tracers provide information on the extent of seawater intrusion and/or mixing with oil-field brines. Groundwater 3H above 1 tritium unit (TU) was observed only in a few select wells close to the Dominguez Gap area and most other well groundwater was aged pre-1952. Based on an initial 14C value for the study site of 90 percent modern carbon (pmc), groundwater age estimates likely extend beyond 20 kyr before present and confirm deep circulation of some native groundwater through multiple aquifers. Enriched values of groundwater δ13CDIC in the absence of SO42− imply enhanced anaerobic microbial methanogenesis. While secular equilibrium was observed for 234U/238U (activity ratios ~1) in host matrices, strong isotopic fractionation in these groundwater samples can be used to obtain information of adsorption/desorption kinetics. Calculated Ra residence times are short, and the associated desorption rate constant is about three orders of magnitude slower than that of the adsorption rate constant. Combined stable- and radio-isotopic results provide unique insights into aquifer

  11. Detection of aquifer system compaction and land subsidence using interferometric synthetic aperture radar, Antelope Valley, Mojave Desert, California

    USGS Publications Warehouse

    Galloway, D.L.; Hudnut, K.W.; Ingebritsen, S.E.; Phillips, S.P.; Peltzer, G.; Rogez, F.; Rosen, P.A.

    1998-01-01

    Interferometric synthetic aperture radar (InSAR) has great potential to detect and quantify land subsidence caused by aquifer system compaction. InSAR maps with high spatial detail and resolution of range displacement (??10 mm in change of land surface elevation) were developed for a groundwater basin (~103 km2) in Antelope Valley, California, using radar data collected from the ERS-1 satellite. These data allow comprehensive comparison between recent (1993-1995) subsidence patterns and those detected historically (1926-1992) by more traditional methods. The changed subsidence patterns are generally compatible with recent shifts in land and water use. The InSAR-detected patterns are generally consistent with predictions based on a coupled model of groundwater flow and aquifer system compaction. The minor inconsistencies may reflect our imperfect knowledge of the distribution and properties of compressible sediments. When used in conjunction with coincident measurements of groundwater levels and other geologic information, InSAR data may be useful for constraining parameter estimates in simulations of aquifer system compaction.

  12. A 10-year plan to study the aquifer system of Indian Wells Valley, California

    USGS Publications Warehouse

    Lipinski, Paul; Knochenmus, Darwin D.

    1981-01-01

    Water needs of the population of Indian Wells Valley, Calif., must be met through further development of ground-water resources. Studies show that annual ground-water pumpage there has increased since 1945 and has exceeded mean annual recharge since 1966. Continued and increased stress on the aquifer system of the valley is expected because population in the valley is predicted to double by 1998 and triple by 2020, based on 1977 population figures. The U.S. Geological Survey proposes a 10-year program to develop a data base to aid in evaluation of future water-management alternatives. A study plan has been developed that describes present and potential problems and objectives of the program, and outlines work items to be undertaken in the study area. (USGS)

  13. Time-series ground-water-level and aquifer-system compaction data, Edwards Air Force Base, Antelope Valley, California, January 1991 through September 1993

    USGS Publications Warehouse

    Freeman, L.A.

    1996-01-01

    As part of a study by the U.S. Geological Survey, a monitoring program was implemented to collect time-series ground-water-level and aquifer-system compaction data at Edwards Air Force Base, California. The data presented in this report were collected from 18 piezometers, 3 extensometers, 1 barometer, and 1 rain gage from January 1991 through September 1993. The piezometers and extensometers are at eight sites in the study area. This report discusses the ground-water-level and aquifer-system compaction monitoring networks, and presents the recorded data in graphs. The data reported are available in the data base of the U.S. Geological Survey.

  14. Digital model of the unconsolidated aquifer system in the Modesto area, Stanislaus and San Joaquin Counties, California

    USGS Publications Warehouse

    Londquist, Clark J.

    1981-01-01

    A digital mathematical model of the unconsolidated alluvial aquifer system in the Modesto area, Calif., has been developed which can be used to determine the effects of increased pumping and water use of future water levels in the aquifer system. The model is divided into two units. The lower unit is confined in the western part of the study area by a confining clay bed; elsewhere in this unit the aquifer is unconfined. The upper unit represents an unconfined aquifer and lies above the clay bed or its extension. Where the clay bed is absent the upper and lower units are considered as a single aquifer. The model, as calibrated, can evaluate with reasonable accuracy the effects on water levels of changing stresses and stress patterns only within the area of primary interest for the upper unit. In other areas of the upper unit and for the lower unit, predicted changes should be looked upon as, at best, representing only general trends. (USGS)

  15. Assessing the Vulnerability of Public-Supply Wells to Contamination: Central Valley Aquifer System near Modesto, California

    USGS Publications Warehouse

    Jagucki, Martha L.; Jurgens, Bryant C.; Burow, Karen R.; Eberts, Sandra M.

    2009-01-01

    This fact sheet highlights findings from the vulnerability study of a public-supply well in Modesto, California. The well selected for study pumps on average about 1,600 gallons per minute from the Central Valley aquifer system during peak summer demand. Water samples were collected at the public-supply well and at monitoring wells installed in the Modesto vicinity. Samples from the public-supply wellhead contained the undesirable constituents uranium, nitrate, arsenic, volatile organic compounds (VOCs), and pesticides, although none were present at concentrations exceeding drinking-water standards. Of these contaminants, uranium and nitrate pose the most significant water-quality risk to the public-supply well because human activities have caused concentrations in groundwater to increase over time. Overall, study findings point to four primary factors that affect the movement and (or) fate of contaminants and the vulnerability of the public-supply well in Modesto: (1) groundwater age (how long ago water entered, or recharged, the aquifer); (2) irrigation and agricultural and municipal pumping that drives contaminants downward into the primary production zone of the aquifer; (3) short-circuiting of contaminated water down the public-supply well during the low-pumping season; and (4) natural geochemical conditions of the aquifer. A local-scale computer model of groundwater flow and transport to the public-supply well was constructed to simulate long-term nitrate and uranium concentrations reaching the well. With regard to nitrate, two conflicting processes influence concentrations in the area contributing recharge to the well: (1) Beneath land that is being farmed or has recently been farmed (within the last 10 to 20 years), downward-moving irrigation waters contain elevated nitrate concentrations; yet (2) the proportion of agricultural land has decreased and the proportion of urban land has increased since 1960. Urban land use is associated with low nitrate

  16. Simulation of Ground-Water Flow in the Irwin Basin Aquifer System, Fort Irwin National Training Center, California

    USGS Publications Warehouse

    Densmore, Jill N.

    2003-01-01

    Ground-water pumping in the Irwin Basin at Fort Irwin National Training Center, California resulted in water-level declines of about 30 feet from 1941 to 1996. Since 1992, artificial recharge from wastewater-effluent infiltration and irrigation-return flow has stabilized water levels, but there is concern that future water demands associated with expansion of the base may cause a resumption of water-level declines. To address these concerns, a ground-water flow model of the Irwin Basin was developed to help better understand the aquifer system, assess the long-term availability and quality of ground water, and evaluate ground-water conditions owing to current pumping and to plan for future water needs at the base. Historical data show that ground-water-level declines in the Irwin Basin between 1941 and 1996, caused the formation of a pumping depression near the pumped wells, and that recharge from the wastewater-treatment facility and disposal area caused the formation of a recharge mound. There have been two periods of water-level recovery in the Irwin Basin since the development of ground water in this basin; these periods coincide with a period of decreased pumpage from the basin and a period of increased recharge of water imported from the Bicycle Basin beginning in 1967 and from the Langford Basin beginning in 1992. Since 1992, artificial recharge has exceeded pumpage in the Irwin Basin and has stabilized water-level declines. A two-layer ground-water flow model was developed to help better understand the aquifer system, assess the long-term availability and quality of ground water, and evaluate ground-water conditions owing to current pumping and to plan for future water needs at the base. Boundary conditions, hydraulic conductivity, altitude of the bottom of the layers, vertical conductance, storage coefficient, recharge, and discharge were determined using existing geohydrologic data. Rates and distribution of recharge and discharge were determined from

  17. Ground-water-level monitoring, basin boundaries, and potentiometric surfaces of the aquifer system at Edwards Air Force Base, California, 1992

    USGS Publications Warehouse

    Rewis, D.L.

    1995-01-01

    A ground-water-level monitoring program was implemented at Edwards Air Force Base, California, from January through December 1992 to monitor spatial and temporal changes in poten-tiometric surfaces that largely are affected by ground-water pumping. Potentiometric-surface maps are needed to determine the correlation between declining ground- water levels and the distribution of land subsidence. The monitoring program focused on areas of the base where pumping has occurred, especially near Rogers Lake, and involved three phases of data collection: (1) well canvassing and selection, (2) geodetic surveys, and (3) monthly ground-water-level measurements. Construction and historical water- level data were compiled for 118 wells and pi-ezometers on or near the base, and monthly ground-water-level measurements were made in 82 wells and piezometers on the base. The compiled water-level data were used in conjunction with previously collected geologic data to identify three types of no-flow boundaries in the aquifer system: structural boundaries, a principal-aquifer boundary, and ground-water divides. Heads were computed from ground-water-level measurements and land-surface altitudes and then were used to map seasonal potentiometric surfaces for the principal and deep aquifers underlying the base. Pumping has created a regional depression in the potentiometric surface of the deep aquifer in the South Track, South Base, and Branch Park well-field area. A 15-foot decline in the potentiometric surface from April to September 1992 and 20- to 30-foot drawdowns in the three production wells in the South Track well field caused locally unconfined conditions in the deep aquifer.

  18. Aquifer-System Compaction and Land Subsidence: Measurements, Analyses, and Simulations-the Holly Site, Edwards Air Force Base, Antelope Valley, California

    USGS Publications Warehouse

    Sneed, Michelle; Galloway, Devin L.

    2000-01-01

    Land subsidence resulting from ground-water-level declines has long been recognized as a problem in Antelope Valley, California. At Edwards Air Force Base (EAFB), ground-water extractions have caused more than 150 feet of water-level decline, resulting in nearly 4 feet of subsidence. Differential land subsidence has caused sinklike depressions and earth fissures and has accelerated erosion of the playa lakebed surface of Rogers Lake at EAFB, adversely affecting the runways on the lakebed which are used for landing aircraft such as the space shuttles. Since 1990, about 0.4 foot of aquifer-system compaction has been measured at a deep (840 feet) borehole extensometer (Holly site) at EAFB. More than 7 years of paired ground-water-level and aquifer-system compaction measurements made at the Holly site were analyzed for this study. Annually, seasonal water-level fluctuations correspond to steplike variations in aquifer-system compaction; summer water-level drawdowns are associated with larger rates of compaction, and winter water-level recoveries are associated with smaller rates of compaction. The absence of aquifer-system expansion during recovery is consistent with the delayed drainage and resultant delayed, or residual, compaction of thick aquitards. A numerical one-dimensional MODFLOW model of aquitard drainage was used to refine estimates of aquifer-system hydraulic parameters that control compaction and to predict potential future compaction at the Holly site. The analyses and simulations of aquifer-system compaction are based on established theories of aquitard drainage. Historical ground-water-level and land-subsidence data collected near the Holly site were used to constrain simulations of aquifer-system compaction and land subsidence at the site for the period 1908?90, and ground-water-level and aquifer- system compaction measurements collected at the Holly site were used to constrain the model for the period 1990?97. Model results indicate that two thick

  19. Groundwater Availability of the Central Valley Aquifer, California

    USGS Publications Warehouse

    Faunt, Claudia C.

    2009-01-01

    California's Central Valley covers about 20,000 square miles and is one of the most productive agricultural regions in the world. More than 250 different crops are grown in the Central Valley with an estimated value of $17 billion per year. This irrigated agriculture relies heavily on surface-water diversions and groundwater pumpage. Approximately one-sixth of the Nation's irrigated land is in the Central Valley, and about one-fifth of the Nation's groundwater demand is supplied from its aquifers. The Central Valley also is rapidly becoming an important area for California's expanding urban population. Since 1980, the population of the Central Valley has nearly doubled from 2 million to 3.8 million people. The Census Bureau projects that the Central Valley's population will increase to 6 million people by 2020. This surge in population has increased the competition for water resources within the Central Valley and statewide, which likely will be exacerbated by anticipated reductions in deliveries of Colorado River water to southern California. In response to this competition for water, a number of water-related issues have gained prominence: conservation of agricultural land, conjunctive use, artificial recharge, hydrologic implications of land-use change, and effects of climate variability. To provide information to stakeholders addressing these issues, the USGS Groundwater Resources Program made a detailed assessment of groundwater availability of the Central Valley aquifer system, that includes: (1) the present status of groundwater resources; (2) how these resources have changed over time; and (3) tools to assess system responses to stresses from future human uses and climate variability and change. This effort builds on previous investigations, such as the USGS Central Valley Regional Aquifer System and Analysis (CV-RASA) project and several other groundwater studies in the Valley completed by Federal, State and local agencies at differing scales. The

  20. Ground-water quality of coastal aquifer systems in the West Coast Basin, Los Angeles County, California, 1999-2002

    USGS Publications Warehouse

    Land, Michael; Reichard, Eric G.; Crawford, Steven M.; Everett, Rhett; Newhouse, Mark W.; Williams, Colin F.

    2004-01-01

    The extensive use of ground water throughout the Central and West Coast Basins of Los Angeles County during the first half of the 20th century resulted in declining water levels, widespread seawater intrusion, and deterioration of water quality along most reaches of the coast. In order to control seawater intrusion in the West Coast Basin, freshwater is injected into a series of wells at two seawater barrier projects. In order to better understand the processes of seawater intrusion and the efficiency of current barrier operation, data were collected from multiple-well monitoring sites installed by the U.S. Geological Survey, from local observation wells, and from production wells. The occurrence and areal extent of native, saline, and recently injected ground water near the coast were defined through the collection and analysis of inorganic and isotopic water-quality data and geophysical logs. Most water in the West Coast Basin with a dissolved-solids concentration less than 500 milligrams per liter generally has a sodium-bicarbonate to sodium/calcium-bicarbonate character. Water with a dissolved-solids concentration greater than 1,000 milligrams per liter also contains variable amounts of calcium and sodium, but chloride is predominant. Most of these high-dissolved-solids wells are perforated in the Upper aquifer systems; several have dissolved-chloride values near that of seawater. Elevated chloride concentrations were measured at many wells in both the Upper and Lower aquifer systems inland from the barrier projects. Although water levels have increased in many wells over the last 30 years, some of the wells do not show a corresponding decrease in dissolved chloride. A detailed assessment of saline ground water was provided by examining the ratios of chloride to bromide, iodide, and boron. Seawater-freshwater mixing lines were constructed using all three ratios. These ion ratios also identify water affected by mixing with injected imported water and oil

  1. Refurbished extensometer sites improve the quality and frequency of aquifer-system compaction and groundwater-level measurements, San Joaquin Valley, California, USA

    NASA Astrophysics Data System (ADS)

    Sneed, M.; Brandt, J.; Solt, M.

    2012-12-01

    Extensive groundwater withdrawal from unconsolidated deposits in the San Joaquin Valley caused widespread aquifer-system compaction and land subsidence locally exceeding 8 meters (m) between 1926 and 1970. To identify the extent of subsidence, a network of 31 extensometers was installed in the 1960s. Importation of surface water in the early 1970s resulted in decreased groundwater pumping, a steady water-level recovery, and a reduced rate of compaction; consequently, data collection was sharply reduced. However, reduced surface-water availability during 1976-77, 1987-92, and 2007-09 caused increased groundwater pumping, lowered water levels, and renewed compaction. The resulting land subsidence has reduced freeboard and flow capacity of the Delta-Mendota Canal (DMC), the California Aqueduct (AQ), and other canals. Four deep (>300-m) cable-type extensometers from the old network, located along the DMC and AQ, were refurbished to identify existing and future subsidence, and to improve the quality and frequency of compaction measurements. Measurement quality was improved at three of these sites by replacing the existing reference tables, which sit atop concrete pads, with new reference tables cemented in 5.5-m boreholes and decoupled from the concrete pads to minimize the measurement of near-surface deformation. A new reference table could not be constructed at the fourth site due to restrictive drill-rig access. Insulated metal shelters were constructed to protect the equipment against environmental exposure at all sites. The frequencies of compaction and water-level measurements at the extensometer sites were improved by instrumenting each with a linear potentiometer and one or more submersible pressure transducers, respectively. An analog dial gauge was installed on each extensometer to provide data continuity in cases of electronic data interruption and to provide verification of potentiometer data. Aquifer-system compaction data from all four sites show

  2. Space geodetic observation of expansion of the San Gabriel Valley, California, aquifer system, during heavy rainfall in winter 2004-2005

    USGS Publications Warehouse

    King, N.E.; Argus, D.; Langbein, J.; Agnew, D.C.; Bawden, G.; Dollar, R.S.; Liu, Z.; Galloway, D.; Reichard, E.; Yong, A.; Webb, F.H.; Bock, Y.; Stark, K.; Barseghian, D.

    2007-01-01

    Starting early in 2005, the positions of GPS stations in the San Gabriel valley region of southern California showed statistically significant departures from their previous behavior. Station LONG moved up by about 47 mm, and nearby stations moved away from LONG by about 10 mm. These changes began during an extremely rainy season in southern California and coincided with a 16-m increase in water level at a nearby well in Baldwin Park and a regional uplift detected by interferometric synthetic aperture radar. No equivalent signals were seen in GPS station position time series elsewhere in southern California. Our preferred explanation, supported by the timing and by a hydrologic simulation, is deformation due to recharging of aquifers after near-record rainfall in 2004-2005. We cannot rule out an aseismic slip event, but we consider such an event unlikely because it requires slip on multiple faults and predicts other signals that are not observed. Copyright 2007 by the American Geophysical Union.

  3. Nitrate Contamination of Deep Aquifers in the Salinas Valley, California

    NASA Astrophysics Data System (ADS)

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

    2011-12-01

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

  4. Using dye tracing to establish groundwater flow paths in a limestone marble aquifer, University of California, Santa Cruz, California

    SciTech Connect

    Hayes, J.; Bertschinger, V. ); Aley, T. )

    1993-04-01

    Areas underlain by karst aquifers are characterized by soluble rock with sinkholes, caves, and a complex underground drainage network. Groundwater issues such as flow direction, well pumping impacts, spring recharge areas, and potential contamination transport routes are greatly complicated by the unique structure of karst aquifers. Standard aquifer analysis techniques cannot be applied unless the structure of the karst aquifer is understood. Water soluble fluorescent dyes are a powerful tool for mapping the irregular subsurface connections and flow paths in karst aquifers. Mapping the subsurface connections allows reasonable estimates of the hydrologic behavior of the aquifer. Two different fluorescent dyes were injected at two points in a limestone karst aquifer system beneath the University of California, Santa Cruz campus. Flow paths in the marble were thought to be closely tied to easily recognized geomorphic alignments of sinkholes associated with fault and fracture zones. The dye tests revealed unexpected and highly complex interconnections. These complex flow paths only partially corresponded to previous surface mapping and aerial photo analysis of fracture systems. Several interfingering but hydrologically unconnected flow paths evidently exist within the cavernous aquifer. For example, dye did not appear at some discharge springs close to the dye injection points, but did appear at more distant springs. This study shows how a dye tracing study in a small, well-defined limestone body can shed light on a variety of environmental and hydrological issues, including potential well pumping impact areas, wellhead protection and recharge areas, parking lot runoff injection to aquifers, and drainage routes from hazardous materials storage areas.

  5. Comparison of groundwater flow in Southern California coastal aquifers

    USGS Publications Warehouse

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

    2009-01-01

    Maintaining the sustainability of Southern California coastal aquifers requires joint management of surface water and groundwater (conjunctive use). This requires new data collection and analyses (including research drilling, modern geohydrologic investigations, and development of detailed computer groundwater models that simulate the supply and demand components separately), implementation of new facilities (including spreading and injection facilities for artificial recharge), and establishment of new institutions and policies that help to sustain the water resources and better manage regional development.

  6. Denitrification in a Shallow Aquifer Underlying a Dairy Farm in the Central Valley of California

    NASA Astrophysics Data System (ADS)

    Esser, B. K.; Beller, H. R.; Carle, S. F.; Hudson, G. B.; Kane, S. R.; McNab, W. W.; Moran, J. E.; Tompson, A. F.

    2004-12-01

    Nitrate loading to shallow aquifers from dairy farm operations presents a serious threat to critical groundwater resources in California. Less well known is the extent to which saturated zone denitrification may mitigate the problem by converting nitrate to the benign end-product nitrogen, before nitrate is transported to deeper aquifers used for drinking water. We are carrying out a multi-disciplinary study of saturated zone denitrification, in a dense network of monitoring points at a 1500-cow dairy in Kings County, California. Detailed vertical profiles of anion and cation concentrations, along with dissolved excess nitrogen were obtained at five-foot intervals using temporary direct-push wells. Results show nitrate concentrations in excess of 100 mg/L over the top few meters of the water column, abruptly falling to less than 5 mg/L below a depth of approximately 10m. Over the same interval, dissolved excess nitrogen concentrations sharply increase, indicating that denitrification is responsible for a significant fraction of the nitrate decrease. This pattern is in effect across the entire dairy site. A key aspect of the project is a concurrent focus on understanding the hydrogeology of the site. Regionally, overdraft over the past several decades has resulted in the development of separate shallow (10 m) and deeper (≥ 40 m) aquifer systems. Recharge to the shallow aquifer is derived from low TDS, isotopically depleted Kings River water from a nearby unlined irrigation canal. Local agricultural pumping from the shallow aquifer and infiltration from irrigation water are significant factors in the shallow system. The deeper aquifer is characterized by intensive regional pumping, rapidly decreasing water levels, and the apparent disposition of the shallow aquifer as a perched system for a 1-km2 or more area surrounding the farm. The air gap separating the aquifers is low in oxygen and undergoes pressure changes as water levels fluctuate below. Age dating and

  7. Assessing the susceptibility to contamination of two aquifer systems used for public water supply in the Modesto and Fresno metropolitan areas, California, 2001 and 2002

    USGS Publications Warehouse

    Wright, Michael T.; Belitz, Kenneth; Johnson, Tyler D.

    2004-01-01

    Ground-water samples were collected from 90 active public supply wells in the Fresno and Modesto metropolitan areas as part of the California Aquifer Susceptibility (CAS) program. The CAS program was formed to examine the susceptibility to contamination of aquifers that are tapped by public supply wells to serve the citizens of California. The objectives of the program are twofold: (1) to evaluate the quality of ground water used for public supply using volatile organic compound (VOC) concentrations in ground-water samples and (2) to determine if the occurrence and distribution of low level VOCs in ground water and characteristics, such as land use, can be used to predict aquifer susceptibility to contamination from anthropogenic activities occurring at, or near, land surface. An evaluation was made of the relation between VOC occurrence and the explanatory variables: depth to the top of the uppermost well perforation, land use, relative ground-water age, high nitrate concentrations, density of leaking underground fuel tanks (LUFT), and source of recharge water. VOCs were detected in 92 percent of the wells sampled in Modesto and in 72 percent of the wells sampled in Fresno. Trihalomethanes (THM) and solvents were frequently detected in both study areas. Conversely, the gasoline components?benzene, toluene ethylbenzene, and xylenes (BTEX)?were rarely, if at all, detected, even though LUFTs were scattered throughout both study areas. The rare occurrence of BTEX compounds may be the result of their low solubility and labile nature in the subsurface environment. Samples were analyzed for 85 VOCs; 25 were detected in at least one sample. The concentrations of nearly all VOCs detected were at least an order of magnitude below action levels set by drinking water standards. Concentrations of four VOCs exceeded federal and state maximum contaminant levels (MCL): the solvent trichloroethylene (TCE) and the fumigant 1, 2-dibromo-3-chloropropane (DBCP) in Fresno, and the

  8. California Groundwater Ambient Monitoring and Assessment (GAMA) Program Priority Basin Project--shallow aquifer assessment

    USGS Publications Warehouse

    ,

    2013-01-01

    The California State Water Resources Control Board’s (SWRCB) GAMA Program is a comprehensive assessment of statewide groundwater quality in California. From 2004 to 2012, the GAMA Program’s Priority Basin Project focused on assessing groundwater resources used for public drinking-water supplies. More than 2,000 public-supply wells were sampled by U.S. Geological Survey (USGS) for this effort. Starting in 2012, the GAMA Priority Basin Project began an assessment of water resources in shallow aquifers in California. These shallow aquifers provide water for domestic and small community-supply wells, which are often drilled to shallower depths in the groundwater system than public-supply wells. Shallow aquifers are of interest because shallow groundwater may respond more quickly and be more susceptible to contamination from human activities at the land surface, than the deeper aquifers. The SWRCB’s GAMA Program was developed in response to the Groundwater Quality Monitoring Act of 2001 (Water Code sections 10780-10782.3): a public mandate to assess and monitor the quality of groundwater resources used for drinking-water supplies, and to increase the availability of information about groundwater quality to the public. The U.S. Geological Survey is the technical lead of the Priority Basin Project. Stewardship of California’s groundwater resources is a responsibility shared between well owners, communities, and the State. Participants and collaborators in the GAMA Program include Regional Water Quality Control Boards, Department of Water Resources, Department of Public Health, local and regional groundwater management entities, county and local water agencies, community groups, and private citizens. Well-owner participation in the GAMA Program is entirely voluntary.

  9. The Sparta aquifer system in Mississippi

    USGS Publications Warehouse

    Newcome, Roy

    1976-01-01

    A large amount of information is available on the aquifers of Mississippi.  Reports resulting from various areal studies have described the ground-water resources of the areas concerned, but no reports dealing specifically with the entire Mississippi occurrence of individual aquifer systems have previously been prepared.  A series of "aquifer atlases" was deemed the most effective way to describe the character, the potential, and the extent of development of the aquifers and thereby provide water managers with data needed for efficient utilization of available resources.  This report on the Sparta aquifer system is the third in the series.  Information on the aquifers was obtained in the cooperative programs of the U.S. Geological Survey with the Mississippi Board of Water Commissioners and other State and Federal agencies.

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

    NASA Astrophysics Data System (ADS)

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

    2006-12-01

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

  11. Data for ground-water test hole near Butte City, Central Valley aquifer project, California

    USGS Publications Warehouse

    French, James J.; Page, R.W.; Bertoldi, G.L.

    1983-01-01

    This report provides preliminary data for the third of seven test holes drilled as part of the Central Valley Aquifer Project which is part of the National Regional Aquifer Systems Analysis Program. The test hole was drilled in the SW 1/4 NE 1/4 sec. 32, T. 19 N., R. 1 W., Glenn County, California, about one-half mile south of the town of Butte City. Drilled to a depth of 1,432 feet below land surface, the hole is cased to a depth of 82 feet and equipped with three piezometer tubes to depths of 592 feet, 968 feet, and 1,330 feet. A 5-foot well screen is at the bottom of each piezometer. Each screened interval has a cement plug above and below it to isolate it from other parts of the aquifer , and the well bore is filled between the plugs with sediment. Nine cores and 49 sidewall cores were recovered. Laboratory tests were made for mineralogy, hydraulic conductivity, porosity , consolidation, grain-size distribution, Atterberg limits, X-ray diffraction, and chemical quality of water. Geophysical and thermal gradient logs were made. The hole is sampled periodically for chemical analysis and measured for water level in the three tapped zones. This report presents methods used to obtain field samples, laboratory procedures, and the data obtained. (USGS)

  12. Data for ground-water test hole near Nicolaus, Central Valley aquifer project, California

    USGS Publications Warehouse

    French, James J.; Page, R.W.; Bertoldi, Gilbert L.

    1983-01-01

    Preliminary data are provided for the third of seven test holes drilled as a part of the Central Valley Aquifer Project which is part of the National Regional Aquifer Systems Analysis Program. The test hole was drilled in the SW 1/4 NE 1/4 sec. 2, T.12N., R.3E., Sutter County, California, about 1 1/2 miles northwest of the town of Nicolaus. Drilled to a depth of 1,150 feet below land surface, the hole is cased to a depth of 100 feet and equipped with three piezometer tubes to depths of 311, 711, and 1,071 feet. A 5-foot well screen is set in sand at the bottom of each piezometer. Each screened interval has a cement plug above and below it to isolate it from other parts of the aquifer, and the well bore is filled between the plugs with sediment. Thirty-one cores and 34 sidewall cores were recovered. Laboratory tests were made for minerology, consolidation, grain-size distribution, Atterberg limits, X-ray diffraction, thermal conductivity, and chemical analysis of water. Geophysical and thermal gradient logs were made. The hole is sampled periodically for chemical analysis of the three tapped zones and measured for water level. This report presents methods used to obtain field samples, laboratory procedures, and the data obtained. (USGS)

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

    USGS Publications Warehouse

    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.

  14. Hydrogeologic framework of the North Carolina Coastal Plain aquifer system

    USGS Publications Warehouse

    Winner, M.D.; Coble, R.W.

    1989-01-01

    The hydrogeologic framework of the North Carolina Coastal Plain aquifer system consists of ten aquifers separated by nine confining units. From top to bottom the aquifers are: the surficial aquifer, Yorktown aquifer, Pungo River aquifer, Castle Hayne aquifer, Beaufort aquifer, Peedee aquifer, Black Creek aquifer, upper Cape Fear aquifer, lower Cape Fear aquifer, and the Lower Cretaceous aquifer. The uppermost aquifer (the surficial aquifer in most places) is a water-table aquifer and the bottom of the system is underlain by crystalline bedrock. The sedimentary deposits forming the aquifers are of Holocene to Cretaceous age and are composed mostly of sand with lesser amounts of gravel and limestone. Confining units between aquifers are composed primarily of clay and silt. The thickness of the aquifers ranges from zero along the Fall Line to more than 10,000 feet at Cape Hatteras. Prominent structural features are the increasing easterly homoclinal dip of the sediments and the Cape Fear arch, the axis of which trends in a southeast direction. The stratigraphic continuity is determined from correlations of 161 geophysical logs along with data from drillers' and geologists' logs. Aquifers were defined by means of these logs plus water-level and water-quality data and evidence of the continuity of pumping effects. Eighteen hydrogeologic sections depict the correlation of these aquifers throughout the Coastal Plain.

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

    USGS Publications Warehouse

    Nishikawa, T.

    1997-01-01

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

  16. Origins of seawater intrusion in a coastal aquifer - A case study of the Pajaro Valley, California

    USGS Publications Warehouse

    Bond, L.D.; Bredehoeft, J.D.

    1987-01-01

    Seawater may enter and contaminate stratified coastal aquifers through a number of different pathways. These pathways and their relative contribution are examined in the Pajaro Valley, California, a coastal area with extensive groundwater development. This study considers three pathways of possible intrusion of the primary confined aquifer: (1) onshore leakage from brackish sources, the estuary and sloughs, through the confining layer; (2) near-shore leakage from the ocean through the confining layer; and (3) offshore flow from the ocean through the submarine canyon outcrop of the aquifer. Groundwater flow and seawater intrusion are simulated using an areal, two-dimensional solute-transport computer model. This analysis indicates that leakage through confining layers is the principal mechanism of recharge to the aquifer. Although lateral flow through the offshore outcrop contaminates the aquifer, as a whole, at a higher rate, vertical leakage through the sea floor initially is the main pathway of seawater intrusion to the onshore portion of the aquifer. It is likely that leakage generally is the dominant mechanism of recharge and initial cause of seawater intrusion for poorly-confined, stratified coastal aquifers. This analysis suggests that a significant time interval follows the initial observation of seawater intrusion, during which remedial action can be taken to control lateral flow through the offshore outcrop, which ultimately will be the largest component of future intrusion in these aquifers. ?? 1987.

  17. Data for ground-water test hole near Zamora, Central Valley Aquifer Project, California

    USGS Publications Warehouse

    French, J.J.; Page, R.W.; Bertoldi, G.L.

    1982-01-01

    Preliminary data are presented for the first of seven test holes drilled as a part of the Central Valley Aquifer Project which is part of the National Regional Aquifer Systems Analysis Program. The test hole was drilled in the SW 1/4 SE 1/4 sec. 34, T. 12 N. , R. 1 E., Yolo County, California, about 3 miles northeast of the town of Zamora. Drilled to a depth of 2,500 feet below land surface, the hole is cased to a depth of 190 feet and equipped with three piezometer tubes to depths of 947, 1,401, and 2,125 feet. A 5-foot well screen is at the bottom of each piezometer. Eighteen cores and 68 sidewall cores were recovered. Laboratory tests were made for mineralogy, hydraulic conductivity, porosity , consolidation, grain-size distribution, Atterberg limits, X-ray diffraction, diatom identification, thermal conductivity, and chemical analysis of water. Geophysical and thermal gradient logs were made. The hole is sampled periodically for chemical analysis and measured for water level in the three tapped zones. This report presents methods used to obtain field samples, laboratory procedures, and the data obtained. (USGS)

  18. Hydrochemistry of the surficial and intermediate aquifer systems in Florida

    USGS Publications Warehouse

    Berndt, M.P.; Katz, B.G.

    1992-01-01

    Hydrochemistry of the surficial and intermediate aquifer systems in Florida reflects the lithology and mineralogy of units within each aquifer and sources of water to each aquifer. The surficial aquifer system consists of sand, sandstone, clay, limestone, and shell units that are recharged primarily by precipitation. Calcium bicarbonate was the major-ion water type for 53 percent of the surficial aquifer determinations; a mixed water type (no dominant ions) accounted for 37 percent of the determinations. The median dissolved-solids concentration for the surficial aquifer system was 341 milligrams per liter. The intermediate aquifer system consists of limestone, dolomite, sand, and sandstone, and sources of water include downward leakage from the surficial aquifer system and, in some areas, upward leakage from the Upper Floridan aquifer. In northeastern and panhandle areas of Florida, water from the intermediate aquifer system had major-ion and dissolved-solids concentrations similar to water from the surficial aquifer system. In southwestern Florida, the water type in 67 percent of analyses was mixed, and the median dissolved-solids concentration was 642 milligrams per liter. In a northern area of southwestern Florida, hydrochemistry in the limestone aquifer of the intermediate aquifer system is similar to downward leakage from the surficial aquifer system. In a southern area, downward leakage from the surficial aquifer system has calcium and bicarbonate concentrations five times higher than in the northern area, and upward leakage from the Upper Floridan aquifer contains sodium chloride type water from mixing with seawater. In southern southwest Florida, both the limestone aquifer and the overlying sandstone aquifer within the intermediate aquifer system had higher calcium, sodium, chloride, and bicarbonate concentrations than the limestone aquifer in northern southwest Florida.

  19. Can We Mitigate Climate Extremes using Managed Aquifer Recharge: Case Studies California Central Valley and South-Central Arizona, USA

    NASA Astrophysics Data System (ADS)

    Scanlon, B. R.; Reedy, R. C.; Faunt, C. C.; Pool, D. R.; Uhlman, K.

    2015-12-01

    Frequent long-term droughts interspersed with intense floods in the southwestern U.S. underscore the need to store more water to manage these climate extremes. Here we show how managed aquifer recharge can enhance drought resilience in the southwestern U.S. with ~ 70% of California under extreme drought and 75% of Arizona under moderate drought. Data on water sources, transportation, and users were compiled for managed aquifer recharge systems in the Central Valley and south-central Arizona. Groundwater depletion of 115 to 145 km3 in the 1900s created large subsurface reservoirs in thick alluvial basins in these regions. Large canals and aqueducts up to several 100 km long allow water to be imported from reservoirs, mostly in more humid regions. Imported water is either used instead of groundwater or is applied in surface spreading basins primarily during wet periods (≤1.3 km3/yr Central Valley, ≤0.7 km3/yr Arizona) and is extracted during droughts. The dominant water users include irrigators and municipalities both within and outside the managed aquifer recharge systems. Groundwater modeling indicates that recharge basins significantly increase groundwater storage in the Central Valley. Managed aquifer recharge systems significantly enhance drought resilience and increase sustainability of water resources in semiarid regions, complementing surface water reservoirs and conjunctive surface water/groundwater use by providing longer term storage.

  20. A study of deep aquifers underlying coastal Orange County, California

    USGS Publications Warehouse

    Moreland, Joe A.; Singer, John A.

    1969-01-01

    zone, the depth to the base of aquifers containing fresh water ranges from 1,000 to 2,500 feet below mean sea level. The aquifers are composed of fine to medium sand with locally occurring beds of coarse sand and gravel. Permeability generally ranges from less than 50 gallons per day per square foot to 300 gallons per day per square foot. Pressure head increases with depth of the aquifer to as much as 40 feet above land surface near the base of fresh water. The water is of the sodium bicarbonate type, increasing in salinity with depth. Organic material imparts an amber color to the water, which becomes more distinct with depth. A test well, drilled to 926 feet and perforated from 784 to 884 feet, yielded 1,950 gallons per minute with about 90 feet of drawdown. The water is of the sodium bicarbonate type with dissolved solids of 225 mg/1. Additional studies are needed to evaluate the possibilities of subsidence due to pumping from the deep aquifers, to determine the vertical and horizontal permeabilities of confining beds, and to monitor the changes in water quality and water level.

  1. Estimating Aquifer Properties in the San Joaquin Basin, California, through the Analysis of InSAR Data

    NASA Astrophysics Data System (ADS)

    Smith, R. G.; Knight, R. J.; Zebker, H. A.; Farr, T. G.; Liu, Z.; Chen, J.; Crews, J.; Reeves, J.

    2015-12-01

    Increased groundwater withdrawal in the San Joaquin Valley, California, due to recent droughts has over-stressed many parts of the aquifer system, resulting in widespread aquifer compaction and land subsidence. Using Interferometric Synthetic Aperture Radar, or InSAR, we measure the magnitude of land subsidence to be as much as 20 cm/year for the period from 2007-2011. By comparing the observed subsidence with current and historic groundwater levels, we estimate that 90% of the observed subsidence is inelastic, or not recoverable. Due to delayed drainage in thick aquitards, we find that the majority (>95%) of compaction is caused by thin clay lenses within the upper and lower aquifers, which agrees with previous studies in the area. We use representative skeletal storage coefficients from previous studies in conjunction with observed subsidence and groundwater levels in a 1-dimensional vertical diffusion model to estimate the effective vertical hydraulic conductivity of the aquifer, and determine it is on the order of 1×10-6 cm/second.

  2. Sources of high-chloride water and managed aquifer recharge in an alluvial aquifer in California, USA

    NASA Astrophysics Data System (ADS)

    O'Leary, David R.; Izbicki, John A.; Metzger, Loren F.

    2015-11-01

    As a result of pumping in excess of recharge, water levels in alluvial aquifers within the Eastern San Joaquin Groundwater Subbasin, 130 km east of San Francisco (California, USA), declined below sea level in the early 1950s and have remained so to the present. Chloride concentrations in some wells increased during that time and exceeded the US Environmental Protection Agency's secondary maximum contaminant level of 250 mg/L, resulting in removal of some wells from service. Sources of high-chloride water include irrigation return in 16 % of sampled wells and water from delta sediments and deeper groundwater in 50 % of sampled wells. Chloride concentrations resulting from irrigation return commonly did not exceed 100 mg/L, although nitrate concentrations were as high as 25 mg/L as nitrogen. Chloride concentrations ranged from less than 100-2,050 mg/L in wells affected by water from delta sediments and deeper groundwater. Sequential electromagnetic logs show movement of high-chloride water from delta sediments to pumping wells through permeable interconnected aquifer layers. δD and δ18O data show most groundwater originated as recharge along the front of the Sierra Nevada, but tritium and carbon-14 data suggest recharge rates in this area are low and have decreased over recent geologic time. Managed aquifer recharge at two sites show differences in water-level responses to recharge and in the physical movement of recharged water with depth related to subsurface geology. Well-bore flow logs also show rapid movement of water from recharge sites through permeable interconnected aquifer layers to pumping wells.

  3. Sources of high-chloride water and managed aquifer recharge in an alluvial aquifer in California, USA

    USGS Publications Warehouse

    O'Leary, David; Izbicki, John A.; Metzger, Loren F.

    2015-01-01

    As a result of pumping in excess of recharge, water levels in alluvial aquifers within the Eastern San Joaquin Groundwater Subbasin, 130 km east of San Francisco (California, USA), declined below sea level in the early 1950s and have remained so to the present. Chloride concentrations in some wells increased during that time and exceeded the US Environmental Protection Agency’s secondary maximum contaminant level of 250 mg/L, resulting in removal of some wells from service. Sources of high-chloride water include irrigation return in 16 % of sampled wells and water from delta sediments and deeper groundwater in 50 % of sampled wells. Chloride concentrations resulting from irrigation return commonly did not exceed 100 mg/L, although nitrate concentrations were as high as 25 mg/L as nitrogen. Chloride concentrations ranged from less than 100–2,050 mg/L in wells affected by water from delta sediments and deeper groundwater. Sequential electromagnetic logs show movement of high-chloride water from delta sediments to pumping wells through permeable interconnected aquifer layers. δD and δ18O data show most groundwater originated as recharge along the front of the Sierra Nevada, but tritium and carbon-14 data suggest recharge rates in this area are low and have decreased over recent geologic time. Managed aquifer recharge at two sites show differences in water-level responses to recharge and in the physical movement of recharged water with depth related to subsurface geology. Well-bore flow logs also show rapid movement of water from recharge sites through permeable interconnected aquifer layers to pumping wells.

  4. Tying California's Water System Together

    NASA Astrophysics Data System (ADS)

    Dogan, M. S.; Singh, K.; Medellin-Azuara, J.; Lund, J. R.

    2015-12-01

    This paper presents updates to a relatively integrated hydro-economic model of California's water supply system (CALVIN), showing how future sustainable groundwater management and climate change are likely to affect the operation of California's statewide water supply system, and particularly the Sacramento-San Joaquin Delta. California's water system connects most parts of the state, so that water policy changes in one part of the state can affect water management and deliveries in distant parts of California. This provides a high level of robustness in this system, and geographically disperses the impacts of local actions.

  5. Delineation and description of the regional aquifer systems of Tennessee; Cumberland Plateau aquifer system

    USGS Publications Warehouse

    Brahana, J.V.; Macy, J.A.; Mulderink, Dolores; Zemo, Dawn

    1986-01-01

    The Cumberland Plateau aquifer system consists of Pennsylvanian sandstones, conglomerates, shales, and coals which underlie the Cumberland Plateau in Tennessee. Major water-bearing zones occur within the sandstones and conglomerates in interconnected fractures. The water-bearing formations are separated by shale and siltstone that retard the vertical circulation of ground water, The Pennington Formation serves as the base of this aquifer system and is an effective confining unit, The Cumberland Plateau aquifer system is an important water source for the Cumberland Plateau, wells and springs from the aquifer system supply most of the rural domestic and public drinking-water supplies, water from wells drilled into the Cumberland Plateau aquifer system is generally of good to excellent quality. Of the 32 water-quality analyses on file from this aquifer. only 2 had dissolved-solids concentrations greater than 500 milligrams per liter, and about three-fourths had less than 200 milligrams per liter dissolved solids, However, no samples from depths greater than 300 feet below land surface have been recorded. Ground water from locations where the sandstones are buried deeply, such as the Wartburg basin, may contain dissolved-solids concentrations greater than 1,000 milligrams per liter.

  6. Nitrate in aquifers beneath agricultural systems

    USGS Publications Warehouse

    Burkart, M.R.; Stoner, J.D.; ,

    2007-01-01

    Research from several regions of the world provides spatially anecdotal evidence to hypothesize which hydrologic and agricultural factors contribute to groundwater vulnerability to nitrate contamination. Analysis of nationally consistent measurements from the U.S. Geological Survey's NAWQA program confirms these hypotheses for a substantial range of agricultural systems. Shallow unconfined aquifers are most susceptible to nitrate contamination associated with agricultural systems. Alluvial and other unconsolidated aquifers are the most vulnerable and also shallow carbonate aquifers that provide a substantial but smaller contamination risk. Where any of these aquifers are overlain by permeable soils the risk of contamination is larger. Irrigated systems can compound this vulnerability by increasing leaching facilitated by additional recharge and additional nutrient applications. The system of corn, soybean, and hogs produced significantly larger concentrations of groundwater nitrate than all other agricultural systems because this system imports the largest amount of N-fertilizer per unit production area. Mean nitrate under dairy, poultry, horticulture, and cattle and grains systems were similar. If trends in the relation between increased fertilizer use and groundwater nitrate in the United States are repeated in other regions of the world, Asia may experience increasing problems because of recent increases in fertilizer use. Groundwater monitoring in Western and Eastern Europe as well as Russia over the next decade may provide data to determine if the trend in increased nitrate contamination can be reversed. If the concentrated livestock trend in the United States is global, it may be accompanied by increasing nitrogen contamination in groundwater. Concentrated livestock provide both point sources in the confinement area and intense non-point sources as fields close to facilities are used for manure disposal. Regions where irrigated cropland is expanding, such as

  7. Nitrate in aquifers beneath agricultural systems.

    PubMed

    Burkart, M R; Stoner, J D

    2007-01-01

    Research from several regions of the world provides spatially anecdotal evidence to hypothesize which hydrologic and agricultural factors contribute to groundwater vulnerability to nitrate contamination. Analysis of nationally consistent measurements from the U.S. Geological Survey's NAWQA program confirms these hypotheses for a substantial range of agricultural systems. Shallow unconfined aquifers are most susceptible to nitrate contamination associated with agricultural systems. Alluvial and other unconsolidated aquifers are the most vulnerable and also shallow carbonate aquifers that provide a substantial but smaller contamination risk. Where any of these aquifers are overlain by permeable soils the risk of contamination is larger. Irrigated systems can compound this vulnerability by increasing leaching facilitated by additional recharge and additional nutrient applications. The system of corn, soybean, and hogs produced significantly larger concentrations of groundwater nitrate than all other agricultural systems because this system imports the largest amount of N-fertilizer per unit production area. Mean nitrate under dairy, poultry, horticulture, and cattle and grains systems were similar. If trends in the relation between increased fertilizer use and groundwater nitrate in the United States are repeated in other regions of the world, Asia may experience increasing problems because of recent increases in fertilizer use. Groundwater monitoring in Western and Eastern Europe as well as Russia over the next decade may provide data to determine if the trend in increased nitrate contamination can be reversed. If the concentrated livestock trend in the United States is global, it may be accompanied by increasing nitrogen contamination in groundwater. Concentrated livestock provide both point sources in the confinement area and intense non-point sources as fields close to facilities are used for manure disposal. Regions where irrigated cropland is expanding, such as

  8. Nitrate in aquifers beneath agricultural systems

    USGS Publications Warehouse

    Burkart, M.R.; Stoner, J.D.

    2002-01-01

    Research from several regions of the world provides spatially anecdotal evidence to hypothesize which hydrologic and agricultural factors contribute to groundwater vulnerability to nitrate contamination. Analysis of nationally consistent measurements from the U.S. Geological Survey's NAWOA program confirms these hypotheses for a substantial range of agricultural systems. Shallow unconfined aquifers are most susceptible to nitrate contamination associated with agricultural systems. Alluvial and other unconsolidated aquifers are the most vulnerable and shallow carbonate aquifers provide a substantial but smaller contamination risk. Where any of these aquifers are overlain by permeable soils the risk of contamination is larger. Irrigated systems can compound this vulnerability by increasing leaching facilitated by additional recharge and additional nutrient applications. The agricultural system of corn, soybeans, and hogs produced significantly larger concentrations of groundwater nitrate than all other agricultural systems, although mean nitrate concentrations in counties with dairy, poultry, cattle and grains, and horticulture systems were similar. If trends in the relation between increased fertilizer use and groundwater nitrate in the United States are repeated in other regions of the world, Asia may experience increasing problems because of recent increases in fertilizer use. Groundwater monitoring in Western and Eastern Europe as well as Russia over the next decade may provide data to determine if the trend in increased nitrate contamination can be reversed. If the concentrated livestock trend in the United States is global, it may be accompanied by increasing nitrogen contamination in groundwater. Concentrated livestock provide both point sources in the confinement area and intense non-point sources as fields close to facilities are used for manure disposal. Regions where irrigated cropland is expanding, such as in Asia, may experience the greatest impact of

  9. Distribution of carbonate-rock aquifers and the potential for their development, southern Nevada and adjacent parts of California, Arizona, and Utah

    USGS Publications Warehouse

    Dettinger, M.D.; Harrill, J.R.; Schmidt, D.L.; Hess, J.W.

    1995-01-01

    In 1985, the State of Nevada entered into a cooperative effort with the U.S. Department of the Interior to study and test the State's carbonate- rock aquifers. The studies were focused on southern Nevada and were intended to address the following concerns: Where is water potentially available in the aquifers?; How much water potentially can bewithdrawn from aquifers?; and What effects might result from development of the aquifers? The studies included basic-data collection, geologic mapping, geophysical and geochemical analyses, well drilling, and aquifer testing. The studies showed that the carbonate rocks are continuous and extensive enough to form regional aquifer systems only beneath thecentral third of the region. About 130,000 acre-feet per year of ground water flows through all the aquifers in this corridor (carbonate and noncarbonate), and about 77,000 acre-feet per year discharges directly from the carbonate-rock aquifers at regional springs in southern Nevada or at discharge areas in Death Valley, California. A larger volume of water -as much as 6 million acre-feet in the upper 100 feet alone-is stored in the rocks. Once depleted, however, that resource would be replenished by natural processes only very slowly. Ultimately, long-term development of the carbonate-rock aquifers would result in depletion of stored water, or in the capture of water that otherwise would discharge from the aquifers of southern Nevada and vicinity, or both. In manyplaces, development might extract water from both carbonate-rock and basin-fill aquifers. Possible effects of developing the carbonate-rock aquifers include declining water levels, decreasing springflow rates, drying up of some streams, playas, and meadows, and changing water quality. Specific impacts would depend upon the magnitude and length of development and site-specific conditions around the areas where the water is withdrawn. Confidence in predictions of the potential effects ofdevelopment of the carbonate

  10. Aquifer Heterogeneity and Solute-Transport Modeling in the Floridan Aquifer System

    NASA Astrophysics Data System (ADS)

    Guo, W.; Maliva, R. G.; Missimer, T. M.

    2008-05-01

    The Floridan Aquifer System (FAS) is one of the most prolific aquifers in the world and is widely used for public and irrigation water supply. The FAS is also increasingly being used as a storage zone for aquifer storage and recovery (ASR) systems, including a 333-well system that is planned as part of the Comprehensive Everglades Restoration Plan (CERP). The FAS is highly heterogeneous with respect to hydraulic conductivity, with meter- scale inter-bed variation exceeding seven orders of magnitude in some cases, even in South Florida where mega-karst is not well developed. Aquifer heterogeneity can have a major impact on ASR system performance because of its affects on the movement and mixing of stored water. Aquifer heterogeneity poses challenges for accurate modeling of the FAS, including solute transport modeling of ASR systems and variable density flow modeling of the freshwater/saltwater interface along coastal areas. Dispersivity is an important parameter in solute transport modeling, which is associated with aquifer heterogeneity. Commonly the values of dispersivity used in solute-transport modeling are derived from literature review and adjusted during model calibration process. Artificially large dispersivity values are often used in solute-transport models of ASR systems as a "fudge factor" to simulate the apparent greater mixing caused by inter-bed heterogeneity. This approach is problematic because the use of artificial hydraulic parameters for calibration opens the results of predictive simulations to question. The use of large dispersivity values to simulate aquifer heterogeneity also does not incorporate other impacts of aquifer heterogeneity, such as differential flow rates and migration distances between beds. The technical challenge is to incorporate aquifer heterogeneity into groundwater models at a scale that is sufficient to adequately simulate its effect on ASR system performance and coastal groundwater flow, while maintaining acceptable

  11. Nitrate in aquifers beneath agricultural systems.

    PubMed

    Burkart, M R; Stoner, J D

    2002-01-01

    Research from several regions of the world provides spatially anecdotal evidence to hypothesize which hydrologic and agricultural factors contribute to groundwater vulnerability to nitrate contamination. Analysis of nationally consistent measurements from the U.S. Geological Survey's NAWOA program confirms these hypotheses for a substantial range of agricultural systems. Shallow unconfined aquifers are most susceptible to nitrate contamination associated with agricultural systems. Alluvial and other unconsolidated aquifers are the most vulnerable and shallow carbonate aquifers provide a substantial but smaller contamination risk. Where any of these aquifers are overlain by permeable soils the risk of contamination is larger. Irrigated systems can compound this vulnerability by increasing leaching facilitated by additional recharge and additional concentrations of groundwater nitrate than all other agricultural systems, although mean nitrate concentrations in counties with dairy, poultry, cattle and grains, and horticulture systems were similar. If trends in the relation between increased fertilizer use and groundwater nitrate in the United States are repeated in other regions of the world, Asia may experience increasing problems because of recent increases in fertilizer use. Groundwater monitoring in Western and Eastern Europe as well as Russia over the next decade may provide data to determine if the trend in increased nitrate contamination can be reversed. If the concentrated livestock trend in the United States is global, it may be accompanied by increasing nitrogen contamination in groundwater. Concentrated livestock provide both point sources in the confinement area and intense non-point sources as fields close to facilities are used for manure disposal. Regions where irrigated cropland is expanding, such as in Asia, may experience the greatest impact of this practice.

  12. Groundwater recharge assessment in an upland sandstone aquifer of southern California

    NASA Astrophysics Data System (ADS)

    Manna, F.; Cherry, J. A.; McWhorter, D. B.; Parker, B. L.

    2016-10-01

    The Chloride Mass Balance (CMB) method was used to obtain long-term recharge values for the Santa Susana Field Laboratory (SSFL) site, which features a groundwater flow system beneath an upland ridge formed of sandstone and shale beds in the Simi Hills, Ventura County, southern California. This application relied on the availability of on-site measurements of bulk atmospheric chloride deposition comprised of dry fallout and wet concentration, a large number of groundwater samples (∼1490) collected over three decades from 206 wells spanning a depth range from 10 to 360 m, and measurements of chloride in surface runoff during rain events. The use of the CMB method is suited to the assessment of recharge for the study area because the mean chloride values in groundwater show minimal spatial trends, indicating no sources other than atmospheric. In addition, the Cl/Br ratio was used to exclude wells with possible anthropogenic chloride. The site-wide average recharge ranges between 1.8 and 9.5% of the mean annual precipitation (455 mm) with a mean value of 4.2%. The measured surface runoff varies from 2.3 to 10.2% with mean value of 6.1% (28 mm) and, therefore, the volume of water lost to evapotranspiration is between 95.9 and 80.3% with a mean value of 89.6% (408 mm). The long-term recharge calculated using the CMB method is consistent with tritium distribution based on a subset of groundwater monitoring wells and with an analysis of steady flow in the groundwater mound beneath the SSFL. Furthermore, the recharge value matches those in the literature for sandstone aquifers in arid and semi-arid climates. This recharge estimate has important relevance for site characterization in terms of constraining the volumetric groundwater flow rates and water balance and understanding the mechanisms of transport towards the water table. Moreover, this is the first application of the CMB in an upland area of California. Hence, the method is demonstrated to be robust and

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

    USGS Publications Warehouse

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

    2015-01-01

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

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

    NASA Astrophysics Data System (ADS)

    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

  15. Enhancing drought resilience with conjunctive use and managed aquifer recharge in California and Arizona

    USGS Publications Warehouse

    Scanlon, Bridget R.; Reedy, Robert C.; Faunt, Claudia; Pool, Donald R.; Uhlman, Kristine;

    2016-01-01

    Projected longer‐term droughts and intense floods underscore the need to store more water to manage climate extremes. Here we show how depleted aquifers have been used to store water by substituting surface water use for groundwater pumpage (conjunctive use, CU) or recharging groundwater with surface water (Managed Aquifer Recharge, MAR). Unique multi‐decadal monitoring from thousands of wells and regional modeling datasets for the California Central Valley and central Arizona were used to assess CU and MAR. In addition to natural reservoir capacity related to deep water tables, historical groundwater depletion further expanded aquifer storage by ~44 km3 in the Central Valley and by ~100 km3 in Arizona, similar to or exceeding current surface reservoir capacity by up to three times. Local river water and imported surface water, transported through 100s of km of canals, is substituted for groundwater (≤15 km3/yr, CU) or is used to recharge groundwater (MAR, ≤1.5 km3/yr) during wet years shifting to mostly groundwater pumpage during droughts. In the Central Valley, CU and MAR locally reversed historically declining water‐level trends, which contrasts with simulated net regional groundwater depletion. In Arizona, CU and MAR also reversed historically declining groundwater level trends in Active Management Areas. These rising trends contrast with current declining trends in irrigated areas that lack access to surface water to support CU or MAR. Use of depleted aquifers as reservoirs could expand with winter flood irrigation or capturing flood discharges to the Pacific (0 – 1.6 km3/yr, 2000–2014) with additional infrastructure in California. Because flexibility and expanded portfolio options translate to resilience, CU and MAR enhance drought resilience through multi‐year storage, complementing shorter term surface reservoir storage, and facilitating water markets.

  16. Enhancing drought resilience with conjunctive use and managed aquifer recharge in California and Arizona

    NASA Astrophysics Data System (ADS)

    Scanlon, Bridget R.; Reedy, Robert C.; Faunt, Claudia C.; Pool, Donald; Uhlman, Kristine

    2016-03-01

    Projected longer-term droughts and intense floods underscore the need to store more water to manage climate extremes. Here we show how depleted aquifers have been used to store water by substituting surface water use for groundwater pumpage (conjunctive use, CU) or recharging groundwater with surface water (managed aquifer recharge, MAR). Unique multi-decadal monitoring from thousands of wells and regional modeling datasets for the California Central Valley and central Arizona were used to assess CU and MAR. In addition to natural reservoir capacity related to deep water tables, historical groundwater depletion further expanded aquifer storage by ˜44 km3 in the Central Valley and by ˜100 km3 in Arizona, similar to or exceeding current surface reservoir capacity by up to three times. Local river water and imported surface water, transported through 100s of km of canals, is substituted for groundwater (≤15 km3 yr-1, CU) or is used to recharge groundwater (MAR, ≤1.5 km3 yr-1) during wet years shifting to mostly groundwater pumpage during droughts. In the Central Valley, CU and MAR locally reversed historically declining water-level trends, which contrasts with simulated net regional groundwater depletion. In Arizona, CU and MAR also reversed historically declining groundwater level trends in active management areas. These rising trends contrast with current declining trends in irrigated areas that lack access to surface water to support CU or MAR. Use of depleted aquifers as reservoirs could expand with winter flood irrigation or capturing flood discharges to the Pacific (0-1.6 km3 yr-1, 2000-2014) with additional infrastructure in California. Because flexibility and expanded portfolio options translate to resilience, CU and MAR enhance drought resilience through multi-year storage, complementing shorter term surface reservoir storage, and facilitating water markets.

  17. Statistical evaluation of variables affecting occurrence of hydrocarbons in aquifers used for public supply, California

    USGS Publications Warehouse

    Landon, Matthew K.; Burton, Carmen A.; Davis, Tracy A.; Belitz, Kenneth; Johnson, Tyler D.

    2014-01-01

    The variables affecting the occurrence of hydrocarbons in aquifers used for public supply in California were assessed based on statistical evaluation of three large statewide datasets; gasoline oxygenates also were analyzed for comparison with hydrocarbons. Benzene is the most frequently detected (1.7%) compound among 17 hydrocarbons analyzed at generally low concentrations (median detected concentration 0.024 μg/l) in groundwater used for public supply in California; methyl tert-butyl ether (MTBE) is the most frequently detected (5.8%) compound among seven oxygenates analyzed (median detected concentration 0.1 μg/l). At aquifer depths used for public supply, hydrocarbons and MTBE rarely co-occur and are generally related to different variables; in shallower groundwater, co-occurrence is more frequent and there are similar relations to the density or proximity of potential sources. Benzene concentrations are most strongly correlated with reducing conditions, regardless of groundwater age and depth. Multiple lines of evidence indicate that benzene and other hydrocarbons detected in old, deep, and/or brackish groundwater result from geogenic sources of oil and gas. However, in recently recharged (since ~1950), generally shallower groundwater, higher concentrations and detection frequencies of benzene and hydrocarbons were associated with a greater proportion of commercial land use surrounding the well, likely reflecting effects of anthropogenic sources, particularly in combination with reducing conditions.

  18. Use of InSAR to identify land-surface displacements caused by aquifer-system compaction in the Paso Robles area, San Luis Obispo County, California, March to August 1997

    USGS Publications Warehouse

    Valentine, D.W.; Densmore, J.N.; Galloway, D.L.; Amelung, Falk

    2000-01-01

    The population in San Luis Obispo County has grown steadily during the 1990s, and some land use has been converted from dry farming to grazing to irrigated vineyards and urban areas. Because insufficient surface-water supplies are available to meet the growing demand, ground-water pumpage has increased and the resulting water-level declines have raised concern that this water resource may become overstressed. One particular concern is whether the larger ground-water basins within the county function as large individual basins or whether subsurface structures divide these large basins into smaller subbasins, as differences in ground-water-level data suggest. Interferometric Synthetic Aperture Radar (InSAR) is used in locating land-surface displacement, which may indicate subsurface structures in ground-water basins by determining seasonal and historical land-surface changes. Owing to the high spatial detail of InSAR imagery, the InSAR-derived displacement maps can be used with ground-water-level data to reveal differential aquifer-system compaction related to the presence of geological structures or the distribution of compressible sediments that may define subbasin boundaries. This report describes InSAR displacement maps of the Paso Robles area of San Luis Obispo County and compares them to maps of seasonal changes in ground-water levels to detect the presence of aquifer-system compaction.

  19. Use of InSAR to identify land-surface displacements caused by aquifer-system compaction in the Paso Robles area, San Luis Obispo County, California, March to August 1997

    USGS Publications Warehouse

    Valentine, David W.; Densmore, Jill N.; Galloway, Devin L.; Amelung, Falk

    2001-01-01

    The population in San Luis Obispo County has grown steadily during the 1990s, and some land use has been converted from dry farming to grazing to irrigated vineyards and urban areas. Because insufficient surface-water supplies are available to meet the growing demand, ground-water pumpage has increased and the resulting water-level declines have raised concern that this water resource may become overstressed. One particular concern is whether the larger ground-water basins within the county function as large individual basins or whether subsurface structures divide these large basins into smaller subbasins, as differences in ground-water-level data suggest. Interferometric Synthetic Aperture Radar (InSAR) is used in locating land-surface displacement, which may indicate subsurface structures in ground-water basins by determining seasonal and historical land-surface changes. Owing to the high spatial detail of InSAR imagery, the InSAR-derived displacement maps can be used with ground-water-level data to reveal differential aquifer-system compaction related to the presence of geological structures or the distribution of compressible sediments that may define subbasin boundaries. This report describes InSAR displacement maps of the Paso Robles area of San Luis Obispo County and compares them to maps of seasonal changes in ground-water levels to detect the presence of aquifer-system compaction.

  20. An evaluation of the bedrock aquifer system in northeastern Wisconsin

    USGS Publications Warehouse

    Emmons, P.J.

    1987-01-01

    Model simulations indicate that, by 1914, ground-water withdrawals from the aquifer system had already impacted the study area. Pumping in the Green Bay metropolitan area had lowered the potentiometric heads in aquifer 1 by 69 feet and in aquifer 2 by 55 feet. Model simulations indicate that, by 1981, ground-water withdrawals have caused a cone of depression centered in the city of De Pere area. The influence of the cone affects almost the entire study area and has significantly altered the horizontal and vertical flow regimes in the aquifer system. In 1981, computed drawdowns below the prepumping potentiometric surface of aquifer 1 range from 0 feet on the western side of the study area to 330 feet in the center of the cone of depression. In aquifer 2, the computed drawdown ranges from 0 feet on the western side of the study area to 253 feet in the center of the cone.

  1. Preliminary delineation and description of the regional aquifers of Tennessee : Cumberland Plateau aquifer system

    USGS Publications Warehouse

    Brahana, J.V.; Macy, Jo Ann; Mulderink, Dolores; Zemo, Dawn

    1986-01-01

    The Cumberland Plateau aquifer system consists of Pennsylvanian sandstones, conglomerates, shales, and coals which underlie the Cumberland Plateau in Tennessee. Major water-bearing zones occur within the sandstones and conglomerates in interconnected fractures. The water-bearing formations are separated by shale and siltstone that retard the vertical circulation of ground water. The Pennington Formation serves as the base of this aquifer system and is an effective confining unit. The Cumberland Plateau aquifer system is an important water source for the Cumberland Plateau. Wells and springs from the aquifer system supply most of the rural domestic and public drinking-water supplies. Water from wells drilled into the Cumberland Plateau aquifer system is generally of good to excellent quality. Of the 32 water-quality analyses on file from this aquifer, only 2 had dissolved-solids concentrations greater than 500 milligrams per liter, and about three-fourths had less than 200 milligrams per liter dissolved solids. However, no samples from depths greater than 300 feet below land surface have been recorded. Ground water from locations where the sandstones are buried deeply, such as the Wartburg basin, may contain dissolved-solids concentrations greater than 1,000 milligrams per liter.

  2. Analysis of potential water-supply management options, 2010-60, and documentation of revisions to the model of the Irwin Basin Aquifer System, Fort Irwin National Training Center, California

    USGS Publications Warehouse

    Voronin, Lois M.; Densmore, Jill N.; Martin, Peter

    2014-01-01

    The Fort Irwin National Training Center is considering several alternatives to manage their limited water-supply sources in the Irwin Basin. An existing three-dimensional, finite-difference groundwater-flow model—the U.S. Geological Survey’s MODFLOW—of the aquifer system in the basin was updated and the initial input dataset was supplemented with groundwater withdrawal data for the period 2000–10. The updated model was then used to simulate four combinations, or scenarios, of groundwater withdrawal and recharge over the next 50 years (January 2011 through December 2060). The scenarios included combinations of continuing withdrawals from currently active production wells, supplementing any increases in demand with withdrawals from an inactive production well, reducing withdrawal amounts and rates, and reducing the discharge of treated wastewater to infiltration ponds that provide a recharge source to the underlying aquifer. Results of the simulations indicated that, depending on the scenario implemented, groundwater levels would rise (over the next 50 years) from 40 feet to as much as 65 feet in the northwestern part of the Irwin Basin, and from 5 feet to 10 feet in the southeastern part.

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

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

  4. Assessing Coastal Aquifer Response to Projected Sea Level Rise in California

    NASA Astrophysics Data System (ADS)

    Odigie, K. O.; Hoover, D. J.; Barnard, P.; Swarzenski, P. W.

    2015-12-01

    The rate of global sea-level rise (SLR) has been increasing over the past century, primarily due to global warming and associated melting of polar icecaps. Recent projections indicate that sea level could rise globally by more than 1 m by 2100. Potential impacts of SLR in coastal regions are a concern, especially in California which has a ~1,800 km long coastline and where >70% of the population live in coastal counties. However, information on potential impacts of SLR-driven groundwater inundation in California is limited. In this study, we examined potential impacts of SLR-driven groundwater inundation in select low-lying areas of California, including Arcata, Stinson Beach, and Malibu Lagoon, under +1 m and +2 m SLR scenarios. The results indicate that Arcata, Stinson Beach, and Malibu Lagoon will be impacted by SLR-driven inundation to different extents. For example, ~15% of present-day dry land in Malibu Lagoon will be inundated with groundwater and the lagoon will be expanded by >100% relative to present-day area under the +2 m SLR scenario. In addition, the area with shallow water table ≤2 m from the ground surface will increase substantially with SLR at Malibu Lagoon. SLR-driven groundwater inundation could be problematic in some low-lying coastal regions. Therefore, improved understanding of potential response of coastal aquifers to SLR could help in preparing for mitigation and adaptation.

  5. Effects of unsaturated zone on aquifer test analysis in a shallow-aquifer system

    USGS Publications Warehouse

    Halford, K.J.

    1997-01-01

    A comparison between two hypothetical flow models of an unconfined aquifer, one saturated and the other variably saturated, indicates that the variably saturated model which explicitly models drainage from the unsaturated zone provides a better conceptual framework for analyzing unconfined aquifer test data and better estimates of the lateral and vertical hydraulic conductivity in fine-grained sands. Explicitly accounting for multiple aquifers, well-bore storage, and the effects of delayed drainage from the unsaturated zone increases confidence in aquifer property estimates by removing some assumptions and allowing for the inclusion of early time data and water-table observations in an aquifer test analysis. The inclusion of the unsaturated zone expands the number of parameters to be estimated, but reasonable estimates of lateral and vertical hydraulic conductivity and specific storage of the unconfined aquifer can be obtained. For the cases examined, only the van Genuchten parameter ?? needed to be determined by the test, because the parameters n and ??(r) had a minimal effect on the estimates of hydraulic conductivities, and literature values could be used for these parameters. Estimates of lateral and vertical hydraulic conductivity using MODFLOW were not as good as the VS2DT based estimates and differed from the known values by as much as 30 percent. The hydraulic properties of a surficial aquifer system were estimated through a series of aquifer tests conducted at Cecil Field Naval Air Station in Jacksonville, Florida. Aquifer test results were analyzed by calibrating a variably saturated, radial flow model to the measured drawdowns. Parameter estimation was performed by minimizing the difference between simulated and measured drawdowns with an optimization routine coupled to VS2DT and was constrained by assuming that the hydraulic properties of each aquifer or confining unit were homogeneous. Given the hydrogeologic conditions at the field site, estimating

  6. Hydrogeologic framework of the Michigan Basin regional aquifer system

    USGS Publications Warehouse

    Westjohn, David B.; Weaver, T.L.

    1998-01-01

    Mississippian and younger geologic units form a regional system of aquifers and confining units in the central Lower Peninsula of Michigan. The area of the regional aquifer system is about 22,000 square miles. The aquifer system consists of three bedrock aquifers, which are separated by confining units. Bedrock aquifers and confining units are overlain by surficial glaciofluvial aquifers, which are complexly intercalated with confining beds composed of glacial till and fine-grained lacustrine deposits.Geophysical and geologic logs were used to characterize the hydrogeologic framework of this regional aquifer system and to delineate and map boundaries of aquifers and confining units. Geophysical logs and water-quality data were used to delineate the base of freshwater within the aquifer system and to determine geologic controls on the distribution of freshwater in the aquifer-system units.Pleistocene glaciofluvial deposits are the largest reservoir of fresh ground water in the mapped region, and the thickness of this aquifer unit exceeds 900 feet in some areas. The Saginaw aquifer, the composite of sandstones of Pennsylvanian age, typically ranges in thickness from 100 to 350 feet in areas where this unit is used for water supply. In the western part of the aquifer system, the Saginaw aquifer is separated from glacial deposits by 100 to 150 feet of Jurassic "red beds." "Red beds" are a confining unit, and the Saginaw aquifer contains saline water where it is overlain by these deposits. The Saginaw confining unit, which is principally shale, separates the Saginaw aquifer from the underlying Parma-Bayport aquifer. Thickness of the Saginaw confining unit is about 50 feet in the eastern and the southern parts of the aquifer system, about 100 feet in the north, and 100 to 250 feet in the west. The Parma-Bayport aquifer, which consists mostly of permeable sandstones and carbonates, is 100 to 150 feet thick in most areas. The ParmaBayport aquifer contains freshwater only

  7. Groundwater-quality data in the Monterey–Salinas shallow aquifer study unit, 2013: Results from the California GAMA Program

    USGS Publications Warehouse

    Goldrath, Dara A.; Kulongoski, Justin T.; Davis, Tracy A.

    2016-09-01

    Groundwater quality in the 3,016-square-mile Monterey–Salinas Shallow Aquifer study unit was investigated by the U.S. Geological Survey (USGS) from October 2012 to May 2013 as part of the California State Water Resources Control Board Groundwater Ambient Monitoring and Assessment (GAMA) Program’s Priority Basin Project. The GAMA Monterey–Salinas Shallow Aquifer study was designed to provide a spatially unbiased assessment of untreated-groundwater quality in the shallow-aquifer systems in parts of Monterey and San Luis Obispo Counties and to facilitate statistically consistent comparisons of untreated-groundwater quality throughout California. The shallow-aquifer system in the Monterey–Salinas Shallow Aquifer study unit was defined as those parts of the aquifer system shallower than the perforated depth intervals of public-supply wells, which generally corresponds to the part of the aquifer system used by domestic wells. Groundwater quality in the shallow aquifers can differ from the quality in the deeper water-bearing zones; shallow groundwater can be more vulnerable to surficial contamination.Samples were collected from 170 sites that were selected by using a spatially distributed, randomized grid-based method. The study unit was divided into 4 study areas, each study area was divided into grid cells, and 1 well was sampled in each of the 100 grid cells (grid wells). The grid wells were domestic wells or wells with screen depths similar to those in nearby domestic wells. A greater spatial density of data was achieved in 2 of the study areas by dividing grid cells in those study areas into subcells, and in 70 subcells, samples were collected from exterior faucets at sites where there were domestic wells or wells with screen depths similar to those in nearby domestic wells (shallow-well tap sites).Field water-quality indicators (dissolved oxygen, water temperature, pH, and specific conductance) were measured, and samples for analysis of inorganic

  8. Hydrogeology of the surficial aquifer system, Dade County, Florida

    USGS Publications Warehouse

    Fish, J.E.; Stewart, M.T.

    1991-01-01

    An investigation of the surficial aquifer system in Dade County, begun in 1983, is part of a regional study of the aquifer system in southeastern Florida. Test drilling for lithologic samples, flow measurements during drilling, aquifer testing, and analyses of earlier data permitted delineation of the hydraulic conductivity distribution (on hydrogeologic sections), the aquifers in the system, the generalized transmissivity distribution, and interpretation of the ground-water flow system. The surficial aquifer system, in which an unconfined ground-water flow system exists, is composed of the sediments from land surface downward to the top of a regionally extensive zone of sediments of low permeability called the intermediate confining unit. The aquifer system units, which vary in composition from clay-size sediments to cavernous limestone, are hydro stratigraphically divided into the Biscayne aquifer at the top; an intervening semiconfining unit that consists principally of clayey sand; a predominantly gray limestone aquifer in the Tamiami Formation in western and west-central Dade County; and sand or clayey sand near the base of the surficial aquifer system. The base of the surficial aquifer system ranges from a depth of about 175 to 210 feet below land surface in westernmost Dade County to greater than 270 feet in northeastern Dade County. Test drilling and aquifer-test data indicate a complex hydraulic conductivity distribution. Hydraulic conductivities of the very highly permeable zone of the Biscayne aquifer commonly exceed 10,000 feet per day; in the gray limestone aquifer, they range from 210 to 780 feet per day. Transmissivities of the surficial aquifer system vary locally but have a recognizable areal trend. Estimated values generally are about 300,000 feet squared per day or greater in nearly all of central and eastern Dade County. Transmissivity is lower to the west, decreasing to less than 75,000 feet squared per day in western Dade County. High

  9. Revamping California's Education Finance System.

    ERIC Educational Resources Information Center

    McFadden, Brett

    2003-01-01

    Describes reasons for California's budget deficits and their impact on school finance. Offers five possible solutions to the school funding crises: Restructure the state's tax and revenue system, restore school district revenue-sharing abilities, initiate a top-to-bottom mandate review, provide greater fiscal and program flexibility, and revamp…

  10. Optimized System to Improve Pumping Rate Stability During Aquifer Tests

    NASA Astrophysics Data System (ADS)

    Young, M. H.; Rasmussen, T. C.; Lyons, C.; Pennell, K. D.

    2001-12-01

    Aquifer hydraulic properties are commonly estimated using aquifer tests, which are based on an assumption of a uniform and constant pumping rate. Uncertainties in the flow rate across the borehole-formation interface can be caused by rapid changes in borehole water levels early in an aquifer test, increasing the dynamic head losses. A system is presented that substantially reduces these sources of uncertainty by explicitly accounting for dynamic head losses. The system optimizes the flow rate at the borehole-formation interface, lending it suitable for any type of aquifer test, including constant, step, or ramped withdrawal and injection, as well as sinusoidal. The system was demonstrated for both withdrawal and injection tests in three aquifers at the Savannah River Site. It employs commonly available components (e.g., datalogger, pressure transducers, a variable-speed pump motor, a flow controller, and flow meters), and is inexpensive, highly mobile, and easily set up. No modifications to the control system were required, though a small number of characteristics of the pumping and monitoring system were added to the operating program. The pumping system provided a statistically-significant, constant flow rate with time. The range in pumping variability (95 percent CI) was from +/-0.0041 gpm to +/-0.0144 gpm, across a wide range in field conditions. Additional analyses show that errors in early time pumping rates cause errors in aquifer property estimates, and that optimizing the pumping rates would provide a more error-free data set for estimating aquifer hydraulic properties.

  11. Geohydrologic systems in Kansas, geohydrology of the upper aquifer unit in the western interior plains aquifer system

    USGS Publications Warehouse

    Kenny, J.F.; Wolf, R.J.; Hansen, Cristi V.

    1993-01-01

    The purpose of the investigation is to provide a description of the principal geohydrologic systems in Upper Cambrian through Lower Cretaceous rocks in Kansas. This investigation was made as part of the Central Midwest Regional Aquifer-System Analysis (CMRASA). The CMRASA is one of several major investigations by the U.S. Geological Survey of regional aquifer systems in the United States. These regional investigations are designed to increase knowledge of the flow regime and hydrologic properties of major aquifer systems and to provide quantitative information for the assessment, development, and management of water supplies. The CMRASA study area includes all or parts of 10 Central Midwestern States (Jorgensen and Signor, 1981), as shown of the envelope cover,This Hydrologic Investigations Atlas, which consists of a series of chapters, presents a description of the physical framework and geohydrology of principal aquifers and confining systems in Kansas. Chapter H presents the geohydrology of the upper aquifer unit in the Western Interior Plains aquifer system. The physical framework of the aquifer system in relation to other systems is described by maps and sections showing areal extent and the thickness of rocks that compose the unit. The physical framework of the upper aquifer unit is described in detail in chapter D of the atlas (Hansen and others, in press). The hydrology of the system in relation to that of other systems is described in this chapter by maps showing the altitude of fluid levels and the direction of water movement within the unit. The chemical composition of water in the system is described by maps that show the distribution of dissolved-solids concentrations and the differences in water types on the basis of principal chemical constituents. Chapter A of this atlas series (Wolf and others, 1990) describes the relation of principal geohydrologic systems in Kansas and presents a more detailed discussion of the methods and data used to prepare

  12. Sustainable Capture: Concepts for Managing Stream-Aquifer Systems.

    PubMed

    Davids, Jeffrey C; Mehl, Steffen W

    2015-01-01

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

  13. Facies distributions, recharge-discharge relations, and aquifer sensitivity in a glacial aquifer system, northeastern Indiana

    SciTech Connect

    Fleming, A.H. ); Yarling, M. )

    1994-04-01

    The Huntertown aquifer system underlies about 650 km[sup 2] in the interlobate region of northeastern Indiana and corresponds to a sequence of Saginaw Lobe deposits sandwiched between two Erie Lobe till sheets. The northern part of the system typically consists of a 3 to 10 m thick basal outwash apron composed chiefly of sand and capped by a discontinuous sheet of sandy till. Several small to medium-sized (5 to 30km[sup 2]) ice-contact fans are superposed on this sequence and result in thick (15 to 30 m), transmissive sections of sand and gravel. To the southeast, these sediments grade into finer-grained fan-delta and slackwater facies associated with ancestral Lake Erie. Facies distributions, and thus aquifer connectivity, are related to topographic characteristics of the underlying till sheet, which controlled Saginaw Lobe meltwater drainage. The aquifer system is variably confined by a younger sequence of clayey tills and lacustrine mud. The degree of confinement is related to terrain characteristics, with the thickest till (15 to 25 m) being associated with ridged and moraines in the southern and central parts of the system. These features are characteristic of a regional discharge area and suggest a relatively longer residence time. Sensitivity of aquifers in this part of the system may thus be correspondingly less. The distribution of geochemical facies is much less predictable, however, and may be affected by several independent variables.

  14. Sources and Movement of Saline Groundwater in a Coastal Aquifer, Southern California, USA

    NASA Astrophysics Data System (ADS)

    Anders, R.; Stolp, B. J.; Danskin, W. R.

    2014-12-01

    Development of local groundwater resources in coastal areas is limited by the presence of saline groundwater. For a study in the San Diego area, a geochemical approach was used to investigate the sources and movement of saline groundwater in the coastal aquifer. Chemical and isotopic data were collected from multiple-depth monitoring-well sites near the San Diego coastline at discrete intervals to depths of more than 650 meters. The groundwater samples were analyzed for major and minor ions, the stable isotopes of hydrogen, oxygen, and strontium, and radioactive isotopes of tritium and carbon-14. Each chemical and isotopic tracer preserves some aspect of the hydrologic history of the groundwater ranging from the chemical characteristics (major and minor ions), to the source of water (stable isotopes of oxygen and hydrogen), to the types of rock encountered in the groundwater flow system (strontium isotopes), to time-since-recharge (tritium and carbon-14). By using sodium-to-calcium mass ratios, in combination with the isotopic data, the occurrence of saline groundwater as a result of seawater intrusion was distinguishable from groundwater in a previously-saline aquifer that has been "flushed" by fresher continental recharge. The systematic analysis of these tracers indicate that the sources and movement of saline groundwater in the coastal San Diego area are dominated by: 1) regional flow of higher-elevation precipitation that recharged many thousands of years ago along deep flowpaths; 2) recharge of local precipitation in relatively shallower portions of the flow system; and 3) intrusion of seawater that primarily entered the aquifer during pre-modern times. Use of multiple chemical and isotopic tracers provides unique insight regarding the processes affecting groundwater quality, enabling local water agencies to assess the groundwater resources in the coastal aquifer and begin to reduce the area's reliance on imported water.

  15. Groundwater availability of the Denver Basin aquifer system, Colorado

    USGS Publications Warehouse

    Paschke, Suzanne S.

    2011-01-01

    The Denver Basin aquifer system is a critical water resource for growing municipal, industrial, and domestic uses along the semiarid Front Range urban corridor of Colorado. The confined bedrock aquifer system is located along the eastern edge of the Rocky Mountain Front Range where the mountains meet the Great Plains physiographic province. Continued population growth and the resulting need for additional water supplies in the Denver Basin and throughout the western United States emphasize the need to continually monitor and reassess the availability of groundwater resources. In 2004, the U.S. Geological Survey initiated large-scale regional studies to provide updated groundwater-availability assessments of important principal aquifers across the United States, including the Denver Basin. This study of the Denver Basin aquifer system evaluates the hydrologic effects of continued pumping and documents an updated groundwater flow model useful for appraisal of hydrologic conditions.

  16. Optimized system to improve pumping rate stability during aquifer tests.

    PubMed

    Young, Michael H; Rasmussen, Todd C; Lyons, F Comer; Pennell, Kurt D

    2002-01-01

    Aquifer hydraulic properties are commonly estimated using aquifer tests, which are based on an assumption of a uniform and constant pumping rate. Substantial uncertainties in the flow rate across the borehole-formation interface can be induced by dynamic head losses, caused by rapid changes in borehole water levels early in an aquifer test. A system is presented that substantially reduces these sources of uncertainty by explicitly accounting for dynamic head losses. The system which employs commonly available components (including a datalogger, pressure transducers, a variable-speed pump motor, a flow controller, and flowmeters), is inexpensive, highly mobile, and easily set up. It optimizes the flow rate at the borehole-formation interface, making it suitable for any type of aquifer test, including constant, step, or ramped withdrawal and injection, as well as sinusoidal. The system was demonstrated for both withdrawal and injection tests in three aquifers at the Savannah River Site. No modifications to the control system were required, although a small number of characteristics of the pumping and monitoring system were added to the operating program. The pumping system provided a statistically significant, constant flow rate with time. The range in pumping variability (95% confidence interval) was from +/- 2.58 x 10(-4) L/sec to +/- 9.07 x 10(-4) L/sec, across a wide range in field and aquifer conditions.

  17. Ground-water quality in the southeastern Sacramento Valley aquifer, California, 1996

    USGS Publications Warehouse

    Milby Dawson, Barbara J.

    2001-01-01

    In 1996, the U.S. Geological Survey sampled 29 domestic wells and 2 monitoring wells in the southeastern Sacramento Valley as part of the U.S. Geological Survey's National Water-Quality Assessment (NAWQA) Program. This area, designated as the NAWQA Sacramento subunit study area, was chosen because it had the largest amount of ground-water use in the Sacramento River Basin. The Sacramento subunit study area is about 4,400 square kilometers and includes intense agricultural and urban development. The wells sampled ranged from 14.9 to 79.2 meters deep. Ground-water samples from 31 wells were analyzed for 6 field measurements, 14 inorganic constituents, 6 nutrient constituents, organic carbon, 86 pesticides, 87 volatile organic compounds, tritium (hydrogen-3), radon-222, deuterium (hydrogen-2), and oxygen-18. Nitrate levels were lower than the 2000 drinking-water standards in all but one well, but many detections were in the range that indicated an effect by human activities on ground-water quality. Radon was detected in all wells, and was measured at levels above the proposed Federal 2000 maximum contaminant level in 90 percent of the wells. Five pesticides and one pesticide degradation product were detected in ground-water samples and concentrations were below 2000 drinking-water standards. All pesticides detected during this study have been used in the Sacramento Valley. Thirteen volatile organic compounds were detected in ground water. One detection of trichloroethene was above Federal 2000 drinking-water standards, and another, tetrachloromethane, was above California 1997 drinking-water standards; both occurred in a well that had eight volatile organic compound detections and is near a known source of ground-water contamination. Pesticides and volatile organic compounds were detected in agricultural and urban areas; both pesticides and volatile organic compounds were detected at a higher frequency in urban wells. Ground-water chemistry indicates that natural

  18. Hydrologeology and water quality of the Floridan aquifer system and effect of Lower Floridan aquifer pumping on the Upper Floridan aquifer, Pooler, Chatham County, Georgia, 2011–2012

    USGS Publications Warehouse

    Gonthier, Gerard J.

    2012-01-01

    Two test wells were completed in Pooler, Georgia, in 2011 to investigate the potential of using the Lower Floridan aquifer as a source of water for municipal use. One well was completed in the Lower Floridan aquifer at a depth of 1,120 feet (ft) below land surface; the other well was completed in the Upper Floridan aquifer at a depth of 486 ft below land surface. At the Pooler test site, the U.S. Geological Survey performed flowmeter surveys, packer-isolated slug tests within the Lower Floridan confining unit, slug tests of the entire Floridan aquifer system, and aquifer tests of the Upper and Lower Floridan aquifers. Drill cuttings, geophysical logs, and borehole flowmeter surveys indicate that the Upper Floridan aquifer extends 333 –515 ft below land surface, the Lower Floridan confining unit extends 515–702 ft below land surface, and the Lower Floridan aquifer extends 702–1,040 ft below land surface. Flowmeter surveys indicate that the Upper Floridan aquifer contains two water-bearing zones at depth intervals of 339 –350 and 375–515 ft; the Lower Floridan confining unit contains one zone at a depth interval of 550–620 ft; and the Lower Floridan aquifer contains five zones at depth intervals of 702–745, 745–925, 925–984, 984–1,015, and 1,015–1,040 ft. Flowmeter testing of the test borehole open to the entire Floridan aquifer system indicated that the Upper Floridan aquifer contributed 92.4 percent of the total flow rate of 708 gallons per minute; the Lower Floridan confining unit contributed 3.0 percent; and the Lower Floridan aquifer contributed 4.6 percent. Horizontal hydraulic conductivity of the Lower Floridan confining unit derived from slug tests within three packer-isolated intervals ranged from 0.5 to 10 feet per day (ft/d). Aquifer-test analyses yielded values of transmissivity for the Upper Floridan aquifer, Lower Floridan confining unit, and the Lower Floridan aquifer of 46,000, 700, and 4,000 feet squared per day (ft2/d

  19. Stochastic modeling of a lava-flow aquifer system

    USGS Publications Warehouse

    Cronkite-Ratcliff, Collin; Phelps, Geoffrey A.

    2014-01-01

    This report describes preliminary three-dimensional geostatistical modeling of a lava-flow aquifer system using a multiple-point geostatistical model. The purpose of this study is to provide a proof-of-concept for this modeling approach. An example of the method is demonstrated using a subset of borehole geologic data and aquifer test data from a portion of the Calico Hills Formation, a lava-flow aquifer system that partially underlies Pahute Mesa, Nevada. Groundwater movement in this aquifer system is assumed to be controlled by the spatial distribution of two geologic units—rhyolite lava flows and zeolitized tuffs. The configuration of subsurface lava flows and tuffs is largely unknown because of limited data. The spatial configuration of the lava flows and tuffs is modeled by using a multiple-point geostatistical simulation algorithm that generates a large number of alternative realizations, each honoring the available geologic data and drawn from a geologic conceptual model of the lava-flow aquifer system as represented by a training image. In order to demonstrate how results from the geostatistical model could be analyzed in terms of available hydrologic data, a numerical simulation of part of an aquifer test was applied to the realizations of the geostatistical model.

  20. Alpha-emitting isotopes and chromium in a coastal California aquifer

    USGS Publications Warehouse

    Densmore, Jill N.; Izbicki, John A.; Murtaugh, Joseph M.; Swarzenski, Peter W.; Bullen, Thomas D.

    2014-01-01

    The unadjusted 72-h gross alpha activities in water from two wells completed in marine and alluvial deposits in a coastal southern California aquifer 40 km north of San Diego were 15 and 25 picoCuries per liter (pCi/L). Although activities were below the Maximum Contaminant Level (MCL) of 15 pCi/L, when adjusted for uranium activity; there is concern that new wells in the area may exceed MCLs, or that future regulations may limit water use from the wells. Coupled well-bore flow and depth-dependent water-quality data collected from the wells in 2011 (with analyses for isotopes within the uranium, actinium, and thorium decay-chains) show gross alpha activity in marine deposits is associated with decay of naturally-occurring 238U and its daughter 234U. Radon activities in marine deposits were as high as 2230 pCi/L. In contrast, gross alpha activities in overlying alluvium within the Piedra de Lumbre watershed, eroded from the nearby San Onofre Hills, were associated with decay of 232Th, including its daughter 224Ra. Radon activities in alluvium from Piedra de Lumbre of 450 pCi/L were lower than in marine deposits. Chromium VI concentrations in marine deposits were less than the California MCL of 10 μg/L (effective July 1, 2014) but δ53Cr compositions were near zero and within reported ranges for anthropogenic chromium. Alluvial deposits from the nearby Las Flores watershed, which drains a larger area having diverse geology, has low alpha activities and chromium as a result of geologic and geochemical conditions and may be more promising for future water-supply development.

  1. Aquifer storage and recovery: recent hydrogeological advances and system performance.

    PubMed

    Maliva, Robert G; Guo, Weixing; Missimer, Thomas M

    2006-12-01

    Aquifer storage and recovery (ASR) is part of the solution to the global problem of managing water resources to meet existing and future freshwater demands. However, the metaphoric "ASR bubble" has been burst with the realization that ASR systems are more physically and chemically complex than the general conceptualization. Aquifer heterogeneity and fluid-rock interactions can greatly affect ASR system performance. The results of modeling studies and field experiences indicate that more sophisticated data collection and solute-transport modeling are required to predict how stored water will migrate in heterogeneous aquifers and how fluid-rock interactions will affect the quality of stored water. It has been well-demonstrated, by historic experience, that ASR systems can provide very large volumes of storage at a lesser cost than other options. The challenges moving forward are to improve the success rate of ASR systems, optimize system performance, and set expectations appropriately.

  2. Hydrogeologic framework of the Boise Aquifer system, southwestern Idaho

    SciTech Connect

    Squires, E.; Wood, S.H. ); Osiensky, J.L. )

    1993-04-01

    The City of Boise relies upon the underlying groundwater resource (38,000 acre-feet/year) for 90% of its public water-supply. Basin-fill sediments which comprise this system of aquifers are divisible into five distinct hydrogeologic settings which differ on the basis of sediment type, geophysical log character, and hydraulic properties. A large buried alluvial-fan/fan-delta complex (the Boise Fan) occupies the eastern head of the basin. Down-valley gradations in sediment type show a general increase in unit thickness and sediment color more typically gray; reflecting transition to the lake environment of deposition. Basinward (northwestward), the ancient fan materials grade into lake/fan transitional sediments which grade to predominantly lake sediment which grade to gray mudstones and fine sand layers of the deep lake environment. The depth to which drinking-water aquifers extend is limited by an underlying sequence of relatively impermeable volcanic rocks. Specific capacities of efficient wells, 400--1,200 feet deep and open to 80--100 feet of sand are highest in the lake/fan transition and the lacustrine aquifers of central Boise, lowest for the Boise Fan and intermediate for the deep artesian sand aquifers of west Boise. As a result of screen and filter-pack design based upon attention to sampling drill cuttings, sieve analysis of sands, and geophysical log location of aquifers, efficiency and productivity of new wells has been greatly increased. Groundwater recharge to the deeper aquifers is via permeable surface gravels. Increased groundwater withdrawals have possibly accelerated recharge by increasing vertical hydraulic gradients. Overbored wells with continuous surface-to-depth gravel packs, wells open to multiple aquifers, and improperly abandoned wells with deteriorating casing are also conduits for polluted shallow groundwater to enter the deeper aquifers.

  3. Hydrogeology of the surficial and intermediate aquifer systems in Sarasota and adjacent counties, Florida

    USGS Publications Warehouse

    Barr, G.L.

    1996-01-01

    From 1991 to 1995, the hydrogeology of the surficial aquifer system and the major permeable zones and confining units of the intermediate aquifer system in southwest Florida was studied. The study area is a 1,400-square-mile area that includes Sarasota County and parts of Manatee, De Soto, Charlotte, and Lee Counties. Lithologic, geophysical, hydraulic property, and water-level data were used to correlate the hydrogeology and map the extent of the aquifer systems. Water chemistry was evaluated in southwest Sarasota County to determine salinity of the surficial and intermediate aquifer systems. The surficial aquifer is an unconfined aquifer system that overlies the intermediate aquifer system and ranges from a few feet to over 60 feet in thickness in the study area. Hydraulic properties of the surficial aquifer system determined from aquifer and laboratory tests, and model simulations vary considerably across the study area. The intermediate aquifer system, a confined aquifer system that lies between the surficial and the Upper Floridan aquifers, is composed of alternating confining units and permeable zones. The intermediate aquifer system has three major permeable zones that exhibit a wide range of hydraulic properties. Horizontal flow in the intermediate aquifer system is northeast to southwest. Most of the study area is in a discharge area of the intermediate aquifer system. Water ranges naturally from fresh in the surficial aquifer system and upper permeable zones of the intermediate aquifer system to moderately saline in the lower permeable zone. Water-quality data collected in coastal southwest Sarasota County indicate that ground-water withdrawals from major pumping centers have resulted in lateral seawater intrusion and upconing into the surficial and intermediate aquifer systems.

  4. Monitoring technologies for the evaluation of a Soil-Aquifer-Treatment system in coastal aquifer environments.

    NASA Astrophysics Data System (ADS)

    Kallioras, Andreas; Tsertou, Athanasia; Foglia, Laura; Bumberger, Jan; Vienken, Thomas; Dietrich, Peter; Schüth, Christoph

    2014-05-01

    Artificial recharge of groundwater has an important role to play in water reuse. Treated sewage effluent can be infiltrated into the ground for recharge of aquifers. As the effluent water moves through the soil and the aquifer, it undergoes significant quality improvements through physical, chemical, and biological processes in the underground environment. Collectively, these processes and the water quality improvement obtained are called soil-aquifer-treatment (SAT) or geopurification. Recharge systems for SAT can be designed as infiltration-recovery systems, where all effluent water is recovered as such from the aquifer, or after blending with native groundwater. SAT typically removes essentially all suspended solids, biochemical oxygen demand (BOD), and pathogens (viruses, bacteria, protozoa, and helminthic eggs). Concentrations of synthetic organic carbon, phosphorous, and heavy metals are greatly reduced. The pilot site of LTCP will involve the employment of infiltration basins, which will be using waters of impaired quality as a recharge source, and hence acting as a Soil-Aquifer-Treatment, SAT, system. T he LTCP site will be employed as a pilot SAT system complemented by new technological developments, which will be providing continuous monitoring of the quantitative and qualitative characteristics of infiltrating groundwater through all hydrologic zones (i.e. surface, unsaturated and saturated zone). This will be achieved through the development and installation of an integrated system of prototype sensors, installed on-site, and offering a continuous evaluation of the performance of the SAT system. An integrated approach of the performance evaluation of any operating SAT system should aim at parallel monitoring of all hydrologic zones, proving the sustainability of all involved water quality treatment processes within unsaturated and saturated zone. Hence a prototype system of Time Domain Reflectometry (TDR) sensors will be developed, in order to achieve

  5. Groundwater Recharge Assessment in a Fractured Sandstone Aquifer in Southern California

    NASA Astrophysics Data System (ADS)

    Manna, F.; Parker, B. L.; Cherry, J. A.; McWhorter, D.

    2015-12-01

    This abstract summarizes the preliminary results from groundwater recharge estimates at an inactive industrial research facility located in southern California: the Santa Susana Field Laboratory. The research activities, carried out at this site from 1949 to 2006, caused chemical contamination of the aquifer. For this reason, the correct assessment of groundwater recharge and fluxes is a key topic in order to better understand the mechanism controlling the rate of contaminant transport and fate toward offsite receptors. The study area is about 11.5 km2 and is formed by fractured sandstone with interbedded shale and siltstone on a topographic ridge approximately 300 m above adjacent valleys. The bedrock is mostly exposed at surface with irregularly covered by thin alluvial deposits and vegetation, mostly chaparral. The Chloride Mass Balance method was used to estimate the long term average annual site-wide recharge considering the hydrogeological features of the area, the availability of chloride concentration data and the inherent assumptions of the method. Daily data of precipitation and runoff from 2008 to 2011, chloride concentration data in precipitation, dry deposition, surface water and in hundreds of monitoring wells across the site were available. The average spatial and temporal recharge estimated for the site is 4.7% of the average annual precipitation (452 mm) with a range of variation between 2% and 7%. This result matches other values of recharge at the site and reported in the literature for arid and semi-arid environments in different areas of the world (Scanlon et alii, 2006; Sharda et alii, 2006). Furthermore, the annual average runoff constitutes a small percentage (8%) of total inflow volume and therefore, the main "loss" of water is represented by the evapotranspiration. This result is consistent with the climatic characteristics of California where annual evapotranspiration is reported to be greater than annual precipitation volume (Hidalgo et

  6. Groundwater vulnerability mapping in Guadalajara aquifers system (Western Mexico)

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

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

  7. Supporting Continuous Improvement in California's Education System

    ERIC Educational Resources Information Center

    Darling-Hammond, Linda; Plank, David N.

    2015-01-01

    California's new accountability system originated in the radical decentralization of power and authority from Sacramento to local schools and their communities brought about by the Legislature's adoption of the Local Control Funding Formula (LCFF) in 2013. Under California's previous accountability policies and the federal "No Child Left…

  8. Hydrogeology of the Western Amazon Aquifer System (WAAS)

    NASA Astrophysics Data System (ADS)

    Rosário, Fátima Ferreira do; Custodio, Emilio; Silva, Gerson Cardoso da, Jr.

    2016-12-01

    The Western Amazon Aquifer System (WAAS), as defined and proposed in the present work, encompasses an area of about 2.0·106 km2 located in the northwestern portion of South America. Published and unpublished data were used to define WAAS boundaries and main hydrogeologic characteristics. Petroleum industry data, environmental data, and other diverse thematic data were compiled for this study according to the data's origin. The analysis, treatment and integration of available data allowed us to define the WAAS as a multilayered aquifer system comprised of the Tertiary Solimões Aquifer System (SAS) and the Cretaceous Tikuna Aquifer System (TAS). The thick clay-rich basal strata of the SAS appear to confine the TAS. The SAS is widely used for both domestic and industrial purposes, providing good quality freshwater. The TAS has varying water quality: it contains freshwater near its recharge areas in the Sub-Andean fault belt zone, brackish to brine water in the Sub-Andean basins, and salty water in the Solimões Basin (Brazil). The interpretation and conclusions provided by an increasing understanding of the area's hydrogeology resulting from this work made it possible to propose an improved and new WAAS regional hydrogeologic conceptual model with data and descriptions not previously available. Some surprising results have been later confirmed as true by looking at unpublished reports, logs and field notes. Therefore, this work resulted in new findings and settled the basis for future works, especially for the poorly understood TAS.

  9. Isotopic characterization of three groundwater recharge sources and inferences for selected aquifers in the upper Klamath Basin of Oregon and California, USA

    USGS Publications Warehouse

    Palmer, P.C.; Gannett, M.W.; Hinkle, S.R.

    2007-01-01

    Stable isotope (??D and ??18O) signatures of three principal groundwater recharge areas in the 21,000-km2 upper Klamath Basin are used to infer recharge sources for aquifers in the interior parts of the basin. Two of the principal recharge areas, the Cascade Range on the western and southern margin of the basin and uplands along the eastern margin, are defined by mean annual precipitation that exceeds approximately 60 cm. A third recharge area coincides with the extensive irrigation canal system in the south central part of the basin. The stable isotope signature for Cascade Range groundwater falls near the global meteoric water line (GMWL). The stable isotope signature for the groundwater of the eastern basin uplands also falls near the GMWL, but is depleted in heavy isotopes relative to the Cascade Range groundwater. The stable isotope signature for water from the irrigation canal system deviates from the GMWL in a manner indicative of fractionation by evaporation. Groundwater provenance was previously unknown for two aquifers of interest: that supplying deep (225-792 m), large-capacity irrigation wells along the Oregon-California border, and that of the geothermal system near Klamath Falls. Groundwater produced by the deep irrigation wells along the Oregon-California border appears to be a mixture of eastern-basin groundwater and water with an evaporative isotopic signature. The component with an evaporative isotopic signature appears in some places to consist of infiltrated irrigation water. Chloride data suggest that much of the component with the evaporative isotopic signature may be coming from an adjacent subbasin. After accounting for the 18O shift common in geothermal waters, isotope data suggest that the geothermal groundwater in the upper Klamath Basin may emanate from the eastern basin uplands. Findings demonstrate that stable isotope and chloride data can illuminate certain details of a regional groundwater flow system in a complex geologic setting

  10. Quality assessment of reclaimed water for its possible use for crop irrigation and aquifer recharge in Ensenada, Baja California, Mexico.

    PubMed

    Mendoza-Espinosa, L; Orozco-Borbón, M Victoria; Silva-Nava, Patricia

    2004-01-01

    The city of Ensenada, Baja California, has three wastewater treatment plants and is one of the few cities in Mexico that treats all the wastewater that it generates. The largest wastewater treatment plant, called El Naranjo, treats on average 316 liters per second and complies with even the most stringent Mexican standards although a stricter control has to be achieved in order to avoid environmental and health problems At the moment, only 2% of the treated wastewater is used for the irrigation of sports fields and public landscape. The reclaimed water could be reused for the irrigation of crops for non-human consumption or ornamental products and/or for aquifer recharge. For reuse practices, two facts must be considered: a) an important part of the valley's production is exported to the USA and b) 30% of the city of Ensenada's water supply is obtained from the Maneadero aquifer. There is currently no Mexican legislation to stipulate adequate standards for aquifer recharge and decisions should be based on legislation from other places. Therefore, at the moment there is still a lack of technical and scientific elements to be able to make the best decision about the reuse of the wastewater.

  11. Investigation of sustainable development potential for Ulubey Aquifer System, Turkey

    NASA Astrophysics Data System (ADS)

    Burcu, U.; Hasan, Y.

    2014-09-01

    This study investigates sustainable development potential for Ulubey aquifer system which serves as an important water supply for Usak province (Turkey). In recent years, growing population, accelerating industrial activities and decreasing rainfall, as well as contamination of the surface water resources, made groundwater indispensable to meet the freshwater demands of Usak province. Therefore, a sustainable groundwater development plan has to be set up by determining the sustainable yield of the system, which is the aim of this study. To achieve this goal, a mathematical groundwater flow model is constructed in order to test the alternative development scenarios. Results show that the system preserves equilibrium conditions under present stresses. The future effects of possible increases in stresses are also simulated and based on the dynamic responses of the system to changing stresses; sustainable yield and sustainable pumping rate of the aquifer are determined and compared with the safe yield of the system.

  12. The quality of our Nation's waters: Water quality in basin-fill aquifers of the southwestern United States: Arizona, California, Colorado, Nevada, New Mexico, and Utah, 1993-2009

    USGS Publications Warehouse

    Thiros, Susan A.; Paul, Angela P.; Bexfield, Laura M.; Anning, David W.

    2015-01-01

    The Southwest Principal Aquifers consist of many basin-fill aquifers in California, Nevada, Utah, Arizona, New Mexico, and Colorado. Demands for irrigation and drinking water have substantially increased groundwater withdrawals and irrigation return flow to some of these aquifers. These changes have increased the movement of contaminants from geologic and human sources to depths used to supply drinking water in several basin-fill aquifers in the Southwest.

  13. Hydrology of the Texas Gulf Coast aquifer systems

    USGS Publications Warehouse

    Ryder, P.D.; Ardis, A.F.

    1991-01-01

    A complex, multilayered ground-water flow system exists in the Coastal Plain sediments of Texas. The Tertiary and Quaternary clastic deposits have an areal extent of 114,000 square miles onshore and in the Gulf of Mexico. Two distinct aquifer systems are recognized within the sediments, which range in thickness from a few feet to more than 12,000 feet The older system--the Texas coastal uplands aquifer system-consists of four aquifers and two confining units in the Claiborne and Wilcox Groups. It is underlain by the practically impermeable Midway confining unit or by the top of the geopressured zone. It is overlain by the nearly impermeable Vicksburg-Jackson confining unit, which separates it from the younger coastal lowlands aquifer system. The coastal lowlands aquifer system consists of five permeable zones and two confining units that range in age from Oligocene to Holocene. The hydrogeologic units of both systems are exposed in bands that parallel the coastline. The units dip and thicken toward the Gulf. Quality of water in the aquifer systems is highly variable, with dissolved solids ranging from less than 500 to 150,000 milligrams per liter. Substantial withdrawal from the aquifer systems began in the early 1900's and increased nearly continuously into the 1970's. The increase in withdrawal was relatively rapid from about 1940 to 1970. Adverse hydrologic effects, such as saltwater encroachment in coastal areas, land-surface subsidence in the HoustonGalveston area, and long-term dewatering in the Whiter Garden area, were among some of the factors that caused pumping increases to slow or to cease in the 1970's and 1980's. Ground-water withdrawals in the study area in 1980 were about 1.7 billion gallons per day. Nearly all of the withdrawal was from four units: Permeable zones A, B, and C of Miocene age and younger, and the lower Claiborae-upper Wilcox aquifer. Ground-water levels have declined hundreds of feet in the intensively pumped areas of Houston

  14. Groundwater-quality data for the Madera/Chowchilla–Kings shallow aquifer study unit, 2013–14: Results from the California GAMA Program

    USGS Publications Warehouse

    Shelton, Jennifer L.; Fram, Miranda S.

    2017-02-03

    Groundwater quality in the 2,390-square-mile Madera/Chowchilla–Kings Shallow Aquifer study unit was investigated by the U.S. Geological Survey from August 2013 to April 2014 as part of the California State Water Resources Control Board Groundwater Ambient Monitoring and Assessment Program’s Priority Basin Project. The study was designed to provide a statistically unbiased, spatially distributed assessment of untreated groundwater quality in the shallow aquifer systems of the Madera, Chowchilla, and Kings subbasins of the San Joaquin Valley groundwater basin. The shallow aquifer system corresponds to the part of the aquifer system generally used by domestic wells and is shallower than the part of the aquifer system generally used by public-supply wells. This report presents the data collected for the study and a brief preliminary description of the results.Groundwater samples were collected from 77 wells and were analyzed for organic constituents, inorganic constituents, selected isotopic and age-dating tracers, and microbial indicators. Most of the wells sampled for this study were private domestic wells. Unlike groundwater from public-supply wells, the groundwater from private domestic wells is not regulated for quality in California and is rarely analyzed for water-quality constituents. To provide context for the sampling results, however, concentrations of constituents measured in the untreated groundwater were compared with regulatory and non-regulatory benchmarks established for drinking-water quality by the U.S. Environmental Protection Agency, the State of California, and the U.S. Geological Survey.Of the 319 organic constituents assessed in this study (90 volatile organic compounds and 229 pesticides and pesticide degradates), 17 volatile organic compounds and 23 pesticides and pesticide degradates were detected in groundwater samples; concentrations of all but 2 were less than the respective benchmarks. The fumigants 1,2-dibromo-3-chloropropane (DBCP

  15. 78 FR 77447 - California Wind Energy Association, First Solar, Inc. v. California Independent System Operator...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-12-23

    ... Energy Regulatory Commission California Wind Energy Association, First Solar, Inc. v. California Independent System Operator Corporation, Southern California Edison Company; Notice of Complaint Take notice... Practice and Procedure, 18 CFR 385.206 (2013), California Wind Energy Association and First Solar,...

  16. Ground-water flow analysis of the Mississippi Embayment aquifer system, South-Central United States

    USGS Publications Warehouse

    Arthur, J.K.; Taylor, R.E.

    1998-01-01

    The Mississippi Embayment aquifer system is composed of six regional aquifers covering about 160,000 square miles in parts of Alabama, Arkansas, Illinois, Kentucky, Louisiana, Mississippi, Missouri, and Tennessee. The flow analysis presented in this report as part of the Gulf Coast Regional Aquifer-System Analysis study pertains to five aquifers in sediments of the Wilcox and Claiborne groups of Tertiary age. In descending order, the aquifers are (1) the upper Claiborne, (2) the middle Claiborne, (3) the lower Claiborne-upper Wilcox, (4) the middle Wilcox, and (5) the lower Wilcox. The flow analysis of the sixth aquifer in the aquifer system, the Mississippi River valley alluvial aquifer in sediments of Holocene and Pleistocene age, is presented in chapter D of this Professional Paper.

  17. Potentiometric surface of the intermediate aquifer system, west- central Florida, May 1987

    USGS Publications Warehouse

    Lewelling, B.R.

    1988-01-01

    The intermediate aquifer system within the Southwest Florida Water Management District underlies a 5,000 sq mi area of De Soto, Sarasota, Hardee, Manatee, and parts of Charlotte, Hillsborough, Highlands, and Polk Counties. The intermediate aquifer system occurs between the overlying surficial aquifer system and the underlying Floridan aquifer system, and consists of layers of sand, shell, clay, marl, limestone, and dolom of the Tamiami, Hawthorn, and Tampa Formations of late Tertiary age. The intermediate aquifer system contains one or more water-bearing units separated by discontinuous confining units. This aquifer system is the principal source of potable water in the southwestern part of the study area and is widely used as a source of water in other parts where wells are open to the intermediate aquifer system or to both the intermediate and Floridan aquifer systems. Yields of individual wells open to the intermediate aquifer system range from a few gallons to several hundred gallons per minute. The volume of water withdrawn from the intermediate aquifer system is considerably less than that withdrawn from the Floridan aquifer system in the study area. The surface was mapped by determining the altitude of water levels in a network of wells and is represented on maps by contours that connect points of equal altitude. The compos potentiometric surface of all water-bearing units within the intermediate aquifer system is shown. In areas where multiple aquifers exist, wells open to all aquifers were selected for water level measurements whenever possible. In the southwestern and lower coastal region of the study area, two aquifers and confining units are described for the intermediate aquifer system: the Tamiami-upper Hawthorn aquifer and the underlying lower Hawthorn-upper Tampa aquifer. The potentiometric surface of the Tamiami-upper Hawthorn aquifer is also shown. Water levels are from wells drilled and open exclusively to that aquifer. The exact boundary for the

  18. Hydrogeology of the Cambrian-Ordovician aquifer system at a test well in northeastern Illinois

    USGS Publications Warehouse

    Nicholas, J.R.; Sherrill, M.G.; Young, H.L.

    1987-01-01

    A 3,475-ft-deep test well was drilled in northeastern Illinois near Lake Michigan and the Illinois-Wisconsin State line as part of a regional hydrologic study of the Cambrian-Ordovician aquifer. The well penetrates the Cambrian-Ordovician aquifer system and 40 ft of Precambrian granite. From oldest to youngest the aquifer system consists of the lower Mount Simon aquifer, Mount Simon confining unit, Elmhurst-Mount Simon aquifer, Eau Claire confining unit, Ironton-Galesville aquifer, Franconia confining unit, St. Peter aquifer, and an upper confining unit composed of the Glenwood Formation, Galena Dolomite and Platteville Limestone, and Maquoketa Shale. Aquifer tests were performed on hydrogeologic units that were isolated with inflatable packers. Results indicate that the Ironton-Galesville aquifer has the highest hydraulic conductivity - 10 ft/day. The St. Peter and Elmhurst-Mount Simon aquifers have hydraulic conductivities of 1.8 and 1.5 ft/day, respectively. The Mount Simon confining bed has a hydraulic conductivity of 1.3 ft/day. The Mount Simon confining unit confines saline water present in the lower Mount Simon aquifer. The dissolved solids concentration in water from this aquifer is > than 55,000 mg/L, and the head is at least 50 ft higher than heads in any of the overlying Cambrian and Ordovician aquifers. (USGS)

  19. Surface area and travel time relationships in aquifer treatment systems.

    PubMed

    Fox, Peter; Makam, Roshan

    2009-11-01

    Soil aquifer treatment (SAT) and bank filtration use natural attenuation processes to purify water for subsequent use. Soil aquifer treatment may constitute both unsaturated and saturated flow conditions, while bank filtration systems are primarily saturated flow. This analysis focuses on the saturated zone, where the majority of residence time occurs, in both SAT and bank filtration systems. Sustainable removal mechanisms during subsurface flow are primarily surface-mediated and therefore depend on surface area. By analyzing saturated subsurface flow hydraulics in granular media, a relationship between surface area and travel time was developed. For saturated subsurface flow, the ratio of surface area-to-travel time varied by approximately a factor of 3, for common aquifer materials subject to identical hydraulic gradients. Because travel time criteria often are used to regulate SAT and bank filtration systems, these criteria also may determine the surface area and associated surface-mediated reactions for water purification. The ratio of surface area-to-travel time increases with increasing hydraulic gradient, implying that surface area is relatively constant for specific travel times, even if the hydraulic gradient changes; however, the increasing hydraulic gradient will increase the distance from the recharge zone to the recovery well. Therefore, travel time assessments based on maximum possible hydraulic gradients increase surface area and could provide a conservative limit for surface-mediated reactions. This analysis demonstrates that travel time criteria for SAT and bank filtration systems indirectly provide a minimum surface area that may support sustainable removal mechanisms.

  20. Distribution and origin of salinity in the surficial and intermediate aquifer systems, southwestern Florida

    USGS Publications Warehouse

    Schmerge, David L.

    2001-01-01

    Chloride concentrations in the surficial and intermediate aquifer systems in southwestern Florida indicate a general trend of increasing salinity coastward and with depth. There are some notable exceptions to this trend. Brackish water is present in the sandstone and mid-Hawthorn aquifers in several inland areas in Lee County. In an area near the coast in Collier County, the lower Tamiami aquifer contains freshwater, with brackish water present farther inland. Saline water is present in the lower Tamiami aquifer along the coast in Collier County, but water is brackish in the underlying mid-Hawthorn and Upper Floridan aquifers. The analyses of major ions, hydrogen and oxygen isotopes, and strontium isotopes indicate the primary sources of salinity are underlying aquifers and the Gulf of Mexico. Based on these data, much of the salinity is from upward leakage of brackish water from underlying aquifers. Discharge as diffuse upward leakage and artesian wells are two possible pathways of saltwater intrusion from underlying aquifers. Artesian wells open to multiple aquifers have been pathways of saltwater intrusion in the sandstone and mid-Hawthorn aquifers in much of Lee County. The source of brackish water in the lower Tamiami and mid-Hawthorn aquifers in Collier County may be natural diffuse leakage from underlying aquifers. The source of the saline water in the lower Tamiami aquifer in Collier County is apparently the Gulf of Mexico; it is unclear however, whether this saline water is residual water from former Pleistocene sea invasions or recent saltwater intrusion.

  1. The hydrogeologic framework for the southeastern Coastal Plain aquifer system of the United States

    USGS Publications Warehouse

    Renken, R.A.

    1984-01-01

    Tertiary and Cretaceous age sand aquifers of the southeastern United States Coastal Plain constitute a distinct multistate hydrogeologic regime informally defined as the southeastern sand aquifer. Seven regional hydrogeologic units are defined; four regional aquifer units and three regional confining beds. Sand aquifers of this system consist of quartzose, feldspathic, and coarse to fine sand and sandstone and minor limestone; confining beds are composed of clay, shale, chalk, and marl. Three hydrogeologic units of Cretaceous to Holocene age overlie the sand system: the surficial aquifer, upper confining unit, and Floridan aquifer system. These three units are not part of the southeastern sand aquifer, but are an integral element of the total hydrogeologic system, and some act as a source of recharge to, or discharge from the underlying clastic sediments. Low-permeability strata of Paleozoic to early Mesozoic age form the base off the total system. (USGS)

  2. FPI Cohort Reports: California State University System

    ERIC Educational Resources Information Center

    Quirk, Robert J.

    2013-01-01

    The California State University (CSU) system is the largest higher educational system in the United States. The system has physical assets valued at more than $20 billion (current replacement value) on the "State" side of the house alone. With over 1,200 buildings, and 50 million square foot of mixed-use space, the CSU facility managers…

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

    USGS Publications Warehouse

    Adamski, J.C.; Knowles, Leel

    2001-01-01

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

  4. Summary of the Oahu, Hawaii, Regional Aquifer-System Analysis

    USGS Publications Warehouse

    Nichols, William D.; Shade, Patricia J.; Hunt, Charles D.

    1996-01-01

    island. A regional aquifer system composed of the Waianae aquifer in the Waianae Volcanics and the Koolau aquifer in the Koolau Basalt is subdivided into well-defined areas by geohydrologic barriers. The aquifers are separated by the Waianae confining unit formed by weathering along the Waianae-Koolau unconformity. In some coastal areas, a caprock of sedimentary deposits overlies and confines the aquifers. The island of Oahu has been divided into seven major ground-water areas delineated by deep-seated structural geohydrologic barriers; these areas are further subdivided by shallower internal barriers to ground-water flow. The Koolau rift zone along the eastern (windward) side of the island and the Waianae rift zone to the west (Waianae area) constitute two of the major ground-water areas. North-central Oahu is divided into three smaller ground-water areas, Mokuleia, Waialua, and Kawailoa. The Schofield ground-water area encompasses much of the Schofield Plateau of central Oahu. Southern Oahu is divided into six areas, Ewa, Pearl Harbor, Moanalua, Kalihi, Beretania, and Kaimuki. Southeastern Oahu is divided into the Waialae and Wailupe-Hawaii Kai areas. Along the northeast coast of windward Oahu is the Kahuku ground-water area. The aquifers of Oahu contain shallow freshwater and deeper saltwater flow systems. There are five fresh ground-water flow systems: meteoric freshwater flow diverges from ground-water divides that lie somewhere within the Waianae and Koolau rift zones, forming an interior flow system in central Oahu (which is divided into the northern and southern Oahu flow systems) and exterior flow systems in western (Waianae area) Oahu, eastern (windward) Oahu, and southeastern Oahu. Development of the ground-water resources on Oahu began when the first well was drilled near Honouliuli in the summer of 1879. By 1890, 86 wells had been drilled on the island. From about 1891 to about 1910, development increased rapidly with the drilling of a

  5. Hydrogeophysical methods for analyzing aquifer storage and recovery systems

    SciTech Connect

    Minsley, B.J.; Ajo-Franklin, J.; Mukhopadhyay, A.; Morgan, F.D.

    2009-12-01

    Hydrogeophysical methods are presented that support the siting and monitoring of aquifer storage and recovery (ASR) systems. These methods are presented as numerical simulations in the context of a proposed ASR experiment in Kuwait, although the techniques are applicable to numerous ASR projects. Bulk geophysical properties are calculated directly from ASR flow and solute transport simulations using standard petrophysical relationships and are used to simulate the dynamic geophysical response to ASR. This strategy provides a quantitative framework for determining site-specific geophysical methods and data acquisition geometries that can provide the most useful information about the ASR implementation. An axisymmetric, coupled fluid flow and solute transport model simulates injection, storage, and withdrawal of fresh water (salinity {approx}500 ppm) into the Dammam aquifer, a tertiary carbonate formation with native salinity approximately 6000 ppm. Sensitivity of the flow simulations to the correlation length of aquifer heterogeneity, aquifer dispersivity, and hydraulic permeability of the confining layer are investigated. The geophysical response using electrical resistivity, time-domain electromagnetic (TEM), and seismic methods is computed at regular intervals during the ASR simulation to investigate the sensitivity of these different techniques to changes in subsurface properties. For the electrical and electromagnetic methods, fluid electric conductivity is derived from the modeled salinity and is combined with an assumed porosity model to compute a bulk electrical resistivity structure. The seismic response is computed from the porosity model and changes in effective stress due to fluid pressure variations during injection/recovery, while changes in fluid properties are introduced through Gassmann fluid substitution.

  6. Hydrogeophysical methods for analyzing aquifer storage and recovery systems.

    PubMed

    Minsley, Burke J; Ajo-Franklin, Jonathan; Mukhopadhyay, Amitabha; Morgan, Frank Dale

    2011-01-01

    Hydrogeophysical methods are presented that support the siting and monitoring of aquifer storage and recovery (ASR) systems. These methods are presented as numerical simulations in the context of a proposed ASR experiment in Kuwait, although the techniques are applicable to numerous ASR projects. Bulk geophysical properties are calculated directly from ASR flow and solute transport simulations using standard petrophysical relationships and are used to simulate the dynamic geophysical response to ASR. This strategy provides a quantitative framework for determining site-specific geophysical methods and data acquisition geometries that can provide the most useful information about the ASR implementation. An axisymmetric, coupled fluid flow and solute transport model simulates injection, storage, and withdrawal of fresh water (salinity ∼500 ppm) into the Dammam aquifer, a tertiary carbonate formation with native salinity approximately 6000 ppm. Sensitivity of the flow simulations to the correlation length of aquifer heterogeneity, aquifer dispersivity, and hydraulic permeability of the confining layer are investigated. The geophysical response using electrical resistivity, time-domain electromagnetic (TEM), and seismic methods is computed at regular intervals during the ASR simulation to investigate the sensitivity of these different techniques to changes in subsurface properties. For the electrical and electromagnetic methods, fluid electric conductivity is derived from the modeled salinity and is combined with an assumed porosity model to compute a bulk electrical resistivity structure. The seismic response is computed from the porosity model and changes in effective stress due to fluid pressure variations during injection/recovery, while changes in fluid properties are introduced through Gassmann fluid substitution.

  7. 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

    USGS Publications Warehouse

    Gonthier, Gerard J.; 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

  8. Monitoring induced denitrification in an artificial aquifer recharge system.

    NASA Astrophysics Data System (ADS)

    Grau-Martinez, Alba; Torrentó, Clara; Folch, Albert; Domènech, Cristina; Otero, Neus; Soler, Albert

    2014-05-01

    literature ɛN values of -4o and -22o respectively (Aravena and Robertson, 1998; Pauwels et al., 2000). Ongoing denitrification batch experiments will allow us to determine the specific nitrogen and oxygen isotopic fractionation induced by the organic reactive layer, in order to estimate more precisely the extent of denitrification during artificial aquifer recharge. These results confirmed that the reactive layer induces denitrification in the recharge ponds area, proving the usefulness of an isotopic approach to characterize water quality improvement occurring during artificial aquifer recharge. References 1. Aravena, R., Robertson, W.D., 1998. Use of multiple isotope tracers to evaluate denitrification in ground water: Study of nitrate from a large-flux septic system plume. Ground Water, 36(6): 975-982. 2. Pauwels, H., J.C., Kloppmann, W., 2000. Denitrification and mixing in a schist aquifer: Influence on water chemistry and isotopes. Chemical Geology, 168(3-4): 307-324. Acknowledgment This study was supported by the projects CGL2011-29975-C04-01 from the Spanish Government, 2009SGR-00103 from the Catalan Government and ENPI/2011/280-008 from the European Commission. Please fill in your abstract text.

  9. Review: Groundwater flow and transport modeling of karst aquifers, with particular reference to the North Coast Limestone aquifer system of Puerto Rico

    PubMed Central

    Ghasemizadeh, Reza; Hellweger, Ferdinand; Butscher, Christoph; Padilla, Ingrid; Vesper, Dorothy; Field, Malcolm; Alshawabkeh, Akram

    2013-01-01

    Karst systems have a high degree of heterogeneity and anisotropy, which makes them behave very differently from other aquifers. Slow seepage through the rock matrix and fast flow through conduits and fractures result in a high variation in spring response to precipitation events. Contaminant storage occurs in the rock matrix and epikarst, but contaminant transport occurs mostly along preferential pathways that are typically inaccessible locations, which makes modeling of karst systems challenging. Computer models for understanding and predicting hydraulics and contaminant transport in aquifers make assumptions about the distribution and hydraulic properties of geologic features that may not always apply to karst aquifers. This paper reviews the basic concepts, mathematical descriptions, and modeling approaches for karst systems. The North Coast Limestone aquifer system of Puerto Rico (USA) is introduced as a case study to illustrate and discuss the application of groundwater models in karst aquifer systems to evaluate aquifer contamination. PMID:23645996

  10. Review: Groundwater flow and transport modeling of karst aquifers, with particular reference to the North Coast Limestone aquifer system of Puerto Rico.

    PubMed

    Ghasemizadeh, Reza; Hellweger, Ferdinand; Butscher, Christoph; Padilla, Ingrid; Vesper, Dorothy; Field, Malcolm; Alshawabkeh, Akram

    2012-12-01

    Karst systems have a high degree of heterogeneity and anisotropy, which makes them behave very differently from other aquifers. Slow seepage through the rock matrix and fast flow through conduits and fractures result in a high variation in spring response to precipitation events. Contaminant storage occurs in the rock matrix and epikarst, but contaminant transport occurs mostly along preferential pathways that are typically inaccessible locations, which makes modeling of karst systems challenging. Computer models for understanding and predicting hydraulics and contaminant transport in aquifers make assumptions about the distribution and hydraulic properties of geologic features that may not always apply to karst aquifers. This paper reviews the basic concepts, mathematical descriptions, and modeling approaches for karst systems. The North Coast Limestone aquifer system of Puerto Rico (USA) is introduced as a case study to illustrate and discuss the application of groundwater models in karst aquifer systems to evaluate aquifer contamination.

  11. Preliminary evaluation of the hydrogeologic system in Owens Valley, California

    USGS Publications Warehouse

    Danskin, W.R.

    1988-01-01

    A preliminary, two-layer, steady-state, groundwater flow model was used to evaluate present data and hydrologic concepts of Owens Valley, California. Simulations of the groundwater system indicate that areas where water levels are most affected by changes in recharge and discharge are near toes of alluvial fans and along the edge of permeable volcanic deposits. Sensitivity analysis for each model parameter shows that steady state simulations are most sensitive to uncertainties in evapotranspiration rates. Tungsten Hills, Poverty Hills, and Alabama Hills were found to act as virtually impermeable barriers to groundwater flow. Accurate simulation of the groundwater system between Bishop and Lone Pine appears to be possible without simulating the groundwater system in Round Valley, near Owens Lake, or in aquifer materials more than 1,000 ft below land surface. Although vast amounts of geologic and hydrologic data have been collected for Owens Valley, many parts of the hydrogeologic system have not been defined with sufficient detail to answer present water management questions. Location and extent of geologic materials that impede the vertical movement of water are poorly documented. The likely range of aquifer characteristics, except vertical hydraulic conductivity, is well known, but spatial distribution of these characteristics is not well documented. A set of consistent water budgets is needed, including one for surface water, groundwater, and the entire valley. The largest component of previous water budgets (evapotranspiration) is largely unverified. More definitive estimates of local gains and losses for Owens River are needed. Although groundwater pumpage from each well is measured, the quantity of withdrawal from different zones of permeable material has not been defined. (USGS)

  12. Decision Support System for Aquifer Recharge (AR) and ...

    EPA Pesticide Factsheets

    Aquifer recharge (AR) is a technical method being utilized to enhance groundwater resources through man-made replenishment means, such as infiltration basins and injections wells. Aquifer storage and recovery (ASR) furthers the AR techniques by withdrawal of stored groundwater at a later time for beneficial use. It is a viable adaptation technique for water availability problems. Variants of the water storage practices include recharge through urban green infrastructure and the subsurface injection of reclaimed water, i.e., wastewater, which has been treated to remove solids and impurities. In addition to a general overview of ASR variations, this report focuses on the principles and technical basis for an ASR decision support system (DSS), with the necessary technical references provided. The DSS consists of three levels of tools and methods for ASR system planning and assessment, design, and evaluation. Level 1 of the system is focused on ASR feasibility, for which four types of data and technical information are organized around: 1) ASR regulations and permitting needs, 2) Water demand projections, 3) Climate change and water availability, and 4) ASR sites and technical information. These technical resources are integrated to quantify water availability gaps and the feasibility of using ASR to meet the volume and timing of the water resource shortages. A systemic analysis of water resources was conducted for sustainable water supplies in Las Vegas, Nevada f

  13. Funding California Schools: The Revenue Limit System

    ERIC Educational Resources Information Center

    Weston, Margaret

    2010-01-01

    Tax revenue flows to California's nearly 1,000 school districts through many different channels. According to the Governor's Committee on Education Excellence (2007), this system is so complex that the state cannot determine how revenues are distributed among school districts, and after reviewing a large number of academic studies in the Getting…

  14. Hydrogeology of the Southeastern Coastal Plain aquifer system in Mississippi, Alabama, Georgia, and South Carolina

    USGS Publications Warehouse

    Renken, Robert A.

    1996-01-01

    The Southeastern Coastal Plain aquifer system consists of a thick sequence of unconsolidated to poorly consolidated Cretaceous and Tertiary rocks that extend from Mississippi to South Carolina. Four regional sand and gravel aquifers are separated by three regional confining units of clay, shale, and chalk that do not conform everywhere to stratigraphic boundaries. The change in geologic facies is the most important factor controlling the distribution of transmissivity within the aquifer system.

  15. Geochemical and isotopic composition of ground water with emphasis on sources of sulfate in the upper Floridan Aquifer and intermediate aquifer system in southwest Florida

    USGS Publications Warehouse

    Sacks, Laura A.; Tihansky, Ann B.

    1996-01-01

    In southwest Florida, sulfate concentrations in water from the Upper Floridan aquifer and overlying intermediate aquifer system are commonly above 250 milligrams per liter (the drinking water standard), particularly in coastal areas. Possible sources of sulfate include dissolution of gypsum from the deeper part of the Upper Floridan aquifer or the middle confining unit, saltwater in the aquifer, and saline waters from the middle confining unit and Lower Floridan aquifer. The sources of sulfate and geochemical processes controlling ground-water composition were evaluated for the Peace and Myakka River Basins and adjacent coastal areas of southwest Florida. Samples were collected from 63 wells and a saline spring, including wells finished at different depth intervals of the Upper Floridan aquifer and intermediate aquifer system at about 25 locations. Sampling focused along three ground-water flow paths (selected based on a predevelopment potentiometric-surface map). Ground water was analyzed for major ions, selected trace constituents, dissolved organic carbon, and stable isotopes (delta deuterium, oxygen-18, carbon-13 of inorganic carbon, and sulfur-34 of sulfate and sulfide); the ratio of strontium-87 to strontium-86 was analyzed for waters along one of the flow paths. Chemical and isotopic data indicate that dedolomitization reactions (gypsum and dolomite dissolution and calcite precipitation) control the chemical composition of water in the Upper Floridan aquifer in inland areas. This is confirmed by mass-balance modeling between wells in the shallowest interval in the aquifer along the flow paths. However, gypsum occurs deeper in the aquifer than these wells. Upwelling of sulfate-rich water that previously dissolved gypsum in deeper parts of the aquifer is a more likely source of sulfate than gypsum dissolution in shallow parts of the aquifer. This deep ground water moves to shallower zones in the aquifer discharge area. Saltwater from the Upper Floridan aquifer

  16. Hydrogeology, ground-water movement, and subsurface storage in the Floridan aquifer system in southern Florida

    USGS Publications Warehouse

    Meyer, Frederick W.

    1989-01-01

    The Floridan aquifer system of southern Florida is composed chiefly of carbonate rocks that range in age from early Miocene to Paleocene. The top of the aquifer system in southern Florida generally is at depths ranging from 500 to 1,000 feet, and the average thickness is about 3,000 feet. It is divided into three general hydrogeologic units: (1) the Upper Floridan aquifer, (2) the middle confining unit, and (3) the Lower Floridan aquifer. The Upper Floridan aquifer contains brackish ground water, and the Lower Floridan aquifer contains salty ground water that compares chemically to modern seawater. Zones of high permeability are present in the Upper and Lower Floridan aquifers. A thick, cavernous dolostone in the Lower Floridan aquifer, called the Boulder Zone, is one of the most permeable carbonate units in the world (transmissivity of about 2.5 x 107 feet squared per day). Ground-water movement in the Upper Floridan aquifer is generally southward from the area of highest head in central Florida, eastward to the Straits of Florida, and westward to the Gulf of Mexico. Distributions of natural isotopes of carbon and uranium generally confirm hydraulic gradients in the Lower Floridan aquifer. Groundwater movement in the Lower Floridan aquifer is inland from the Straits of Florida. The concentration gradients of the carbon and uranium isotopes indicate that the source of cold saltwater in the Lower Floridan aquifer is seawater that has entered through the karat features on the submarine Miami Terrace near Fort Lauderdale. The relative ages of the saltwater suggest that the rate of inland movement is related in part to rising sea level during the Holocene transgression. Isotope, temperature, and salinity anomalies in waters from the Upper Floridan aquifer of southern Florida suggest upwelling of saltwater from the Lower Floridan aquifer. The results of the study support the hypothesis of circulating relatively modern seawater and cast doubt on the theory that the

  17. [Dissolved organic matter (DOM) dynamics in karst aquifer systems].

    PubMed

    Yao, Xin; Zou, Sheng-Zhang; Xia, Ri-Yuan; Xu, Dan-Dan; Yao, Min

    2014-05-01

    Dissolved organic matter (DOM) and nutrients have a unique way of producing, decomposing and storing in southwest karst water systems. To understand the biogeochemical cycle of DOM in karst aquifer systems, we investigated the behavioral changes of DOM fluorescence components in Zhaidi karst river system. Two humic-like components (C1 and C2), and one autochthonous tyrosine-like component (C4) were identified using the parallel factor analysis (PARAFAC) model. Compared with the traditional physical and chemical indicators, spatial heterogeneity of DOM was more obvious, which can reflect the subtle changes in groundwater system. Traditional indicators mainly reflect the regional characteristics of karst river system, while DOM fluorescence components reflect the attribute gaps of sampling types.

  18. Summary of hydrologic testing of the Floridan aquifer system at Fort Stewart, coastal Georgia, 2009-2010

    USGS Publications Warehouse

    Gonthier, Gerald J.

    2011-01-01

    Two test wells were completed at Fort Stewart, coastal Georgia, to investigate the potential for using the Lower Floridan aquifer as a source of water to satisfy anticipated, increased water needs. The U.S. Geological Survey, in cooperation with the U.S. Department of the Army, completed hydrologic testing of the Floridan aquifer system at the study site, including flowmeter surveys, slug tests, and 24- and 72-hour aquifer tests by mid-March 2010. Analytical approaches and model simulation were applied to aquifer-test results to provide estimates of transmissivity and hydraulic conductivity of the multilayered Floridan aquifer system. Data from a 24-hour aquifer test of the Upper Floridan aquifer were evaluated by using the straight-line Cooper-Jacob analytical method. Data from a 72-hour aquifer test of the Lower Floridan aquifer were simulated by using axisymmetric model simulations. Results of aquifer testing indicated that the Upper Floridan aquifer has a transmissivity of 100,000 feet-squared per day, and the Lower Floridan aquifer has a transmissivity of 7,000 feet-squared per day. A specific storage for the Floridan aquifer system as a result of model calibration was 3E-06 ft–1. Additionally, during a 72-hour aquifer test of the Lower Floridan aquifer, a drawdown response was observed in two Upper Floridan aquifer wells, one of which was more than 1 mile away from the pumped well.

  19. Numerical Simulation of Groundwater Conditions in a Coastal Aquifer, Southern California, USA

    NASA Astrophysics Data System (ADS)

    Stolp, B. J.; Anders, R.; Danskin, W. R.

    2014-12-01

    Development of local groundwater resources in coastal areas is influenced by freshwater recharge and discharge, topography, geologic structure, and changes in sea level. For the coastal San Diego area, a density-dependent cross-sectional groundwater flow model was constructed to examine the aquifer and flow characteristics. The model domain represents generalized conditions along an east-west transect that is described by data from two multiple-depth monitoring-well sites; the domain extends into the Pacific Ocean to the 120 meter (m) bathymetric contour. Vertically, the model was discretized into four zones that represent geologic formations; each zone was assigned a horizontal permeability based on aquifer testing. Temporally, the model was divided into two stress periods. The first stress period simulates pre-development conditions, with an instantaneous sea-level rise of 120 m starting 6,000 years ago. This is a simplified representation of transient conditions since the last glacial maximum. The second stress period simulates 60 years of groundwater development, which is represented in terms of net fresh water flow through the domain. Near the coast, observed water-quality data indicate (1) brackish-to-hypersaline groundwater at shallow depths, (2) fresh continental recharge at intermediate depths, and (3) seawater intrusion at depths greater than 300 m. In order to simulate these general groundwater conditions, vertical anisotropy of the upper permeability zone was increased, freshwater discharge was constrained to the seafloor (no discharge along the coast), and groundwater development was simulated as exceeding freshwater recharge (additional water is provided by depletion of freshwater reserves). This numerical testing identifies specific factors that influence current conditions and provides an initial assessment of resource management alternatives for the San Diego coastal aquifer.

  20. Aquifer-test analysis of the upper aquifer of the Potomac-Raritan- Magothy aquifer system, Union Beach Borough, Monmouth County, New Jersey

    USGS Publications Warehouse

    Pucci, A.A.; Pope, D.A.; Ivahnenko, Tamara

    1989-01-01

    The hydraulic properties of the upper aquifer of the Potomac-Raritan-Magothy aquifer system and of the overlying and underlying confining units were determined from and aquifer test in the vicinity of Union Beach Borough, New Jersey, near Raritan Bay. The April 1986 test included the pumping of 2 test wells for 72 hours at a combined discharge rate of 1,375 gal/min, and the measurement of water levels in 10 observation wells. No lateral recharge boundary in Raritan Bay affected the observed water-level changes. Assuming leaky artesian conditions, the average transmissivity and storage coefficient of the upper aquifer are 7,754 sq ft/day and 0.00044 respectively. The leakance of the combined confining units ranges from 0.000030 to 0.000076/day/ft. On the basis of lithologic samples from a nearby well, the overlying and underlying confining units were assumed to have similar hydraulic properties. By using this assumption, the vertical hydraulic conductivity of the confining units ranges from 0.010 to 0.027 ft/day. (USGS)

  1. Lithology and base of the surficial aquifer system, Palm Beach County, Florida

    USGS Publications Warehouse

    Miller, Wesley L.

    1987-01-01

    The surficial aquifer system is a major source of freshwater in Palm Beach County. In 1982, public supply withdrawals from the aquifer system totaled 33,543 million gallons, 77.5% of total public supply withdrawals. To evaluate the aquifer system and its geologic framework, a cooperative study with Palm Beach County was begun in 1982 by the U.S. Geological Survey. The surficial aquifer system in Palm Beach County is composed primarily of sand, sandstone, shell, silt, calcareous clay (marl), and limestone deposited during the Pleistocene and Pliocene epochs. In the western two-thirds of Palm Beach County, sediments in the aquifer system are poorly consolidated sand, shell, and sandy limestone. Owing to interspersed calcareous clays and silt and very poorly sorted materials, permeabilities in this zone of the aquifer system are relatively low. Two other zones of the aquifer system are found in the eastern one-third of the county where the sediments are appreciably more permeable than in the west due to better sorting and less silt and clay content. The location of more detailed lithologic logs for wells in these sections, along with data from nearby wells, allowed enhanced interpretation and depiction of the lithology which had previously been generalized. The most permeable zone of the aquifer system in this area is characterized by highly developed secondary porosity where infiltrating rainwater and solution by groundwater have removed calcitic-cementing materials from the sediments to produce interconnected cavities. Increased permeability in the aquifer system is generally coincident with the eastern boundary of the overlying organic soils and Lake Flirt Marl. Lithologic logs of wells in Palm Beach County indicate that sediments forming the aquifer system were deposited directly on the erosional surface of the Hawthorn Formation in some areas. In other locations in the county, lithologic logs indicate that the base of the aquifer system was formed by fluvial

  2. Boron and strontium isotope compositions of groundwater from the La Paz arid coastal aquifer, Baja California Sur, Mexico

    NASA Astrophysics Data System (ADS)

    Mahlknecht, Jürgen; Rosner, Martin; Meixner, Anette

    2016-04-01

    In groundwater studies boron and strontium isotopic compositions can be used to identify natural and anthropogenic sources as well as processes related to groundwater recharge, flow and mixing. The La Paz arid costal aquifer in Baja California Sur, Mexico, is the most important source of drinking and irrigation water for La Paz area and suffers from anthropogenic contamination and intensive exploitation of the aquifer causing seawater intrusion and general groundwater abatement. The relatively un-radiogenic 87Sr/86Sr isotope ratios of the La Paz groundwater range in a narrow field between 0.7054 and 0.7062. In contrast to strontium the boron isotope composition displays a large variability between +27 and +55 permil d11B. The relatively low 87Sr/86Sr ratios of the La Paz groundwater highlight a significant contribution of strontium derived from local terrestrial sediments and igneous rocks with known 87Sr/86Sr ratios between 0.705 and 0.7035. The large variability of d11B values indicate that multiple sources and processes determine the boron isotope composition of La Paz groundwater. Rainwater (high d11B), seawater (~+40 permil) due to seawater intrusions, wastewater (low to medium d11B) and boron derived from the local geology (low to medium d11B) explain most of the observed groundwater d11B variability. However, d11B values higher than modern seawater point to significant boron isotope fractionation by preferential absorption of 10B onto clay minerals during the evolution of some groundwater samples. Due to low boron concentrations in rainwater a significant contribution of 11B-rich rainwater (>+40 permil) on the La Paz groundwater is unlikely.

  3. Preliminary evaluation of the Highland Rim aquifer system in Tennessee for receiving injected wastes

    USGS Publications Warehouse

    Bradley, M.W.

    1986-01-01

    The EPA has authority under the Safe Drinking Water Act to protect underground sources of drinking water from contamination by deep well injection. An aquifer, however, may be exempted from protection and used for injected wastes where the aquifer meets criteria established in the Agency 's Underground Injection Control program. The Highland Rim aquifer system in Tennessee consists of Mississippian age carbonate rocks and occurs from the Valley and Ridge of East Tennessee to west of the Tennessee River. This aquifer contains potable water and is an important source of drinking water for municipal and domestic supplies on the Highland Rim. The Highland Rim aquifer system under parts of the Cumberland Plateau is not currently used as a source of drinking water and is not expected to be used in the future. These areas meet parts of the EPA 's Underground Injection Control criteria for exempting aquifers to receive injected waste. (Author 's abstract)

  4. A groundwater extraction system to control VOCs in a bedrock aquifer

    SciTech Connect

    Wessley, D.J.; Weber, R.H.; Otzelberger, D.G.

    1995-12-31

    Groundwater quality in the bedrock aquifer at a solid waste landfill has been evaluated since 1984. Since that time, several volatile organic compounds (VOCs) have been detected in various bedrock monitoring wells at the site. Continued detection of VOCs in the bedrock aquifer led to an investigation and design of a remediation system to address the contaminated aquifer. This paper discusses the site background, geology, hydrogeology, and landfill characteristics; the methods and results of the landfill monitoring and investigations performed; and the groundwater extraction system which was designed and constructed to control further off-site migration of contaminants in the bedrock aquifer.

  5. Preliminary potentiometric map and flow dynamic characteristics for the upper-basalt confined aquifer system

    SciTech Connect

    Spane, F.A. Jr.; Raymond, R.G.

    1993-09-01

    This report presents the first comprehensive Hanford Site-wide potentiometric map for the upper-basalt confined aquifer system (i.e., the upper Saddle Mountains Basalt). In constructing the potentiometric map, over forty on-site and off-site monitoring wells and boreholes were used. The potentiometric map developed for the upper-basalt confined aquifer is consistent with the areal head pattern indicated for the Mabton interbed, which is a deeper and more areally extensive confined aquifer underlying the Hanford Site. Salient features for the upper-basalt confined aquifer system potentiometric map are described.

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

    USGS Publications Warehouse

    Sheets, Rodney A.; Bossenbroek, Karen E.

    2005-01-01

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

  7. Groundwater-quality data in the Tulare Shallow Aquifer Study Unit, 2014-2015: Results from the California GAMA Priority Basin Project

    USGS Publications Warehouse

    Bennett, George L.; Fram, Miranda S.; Johnson, Tyler

    2017-01-01

    The U.S. Geological Survey collected groundwater samples from 95 domestic wells in Tulare and Kings Counties, California in 2014-2015. The wells were sampled for the Tulare Shallow Aquifer Study Unit of the California State Water Resources Control Board Groundwater Ambient Monitoring and Assessment (GAMA) Program Priority Basin Project’s assessment of the quality of groundwater resources used for domestic drinking water supply. Domestic wells commonly are screened at shallower depths than are public-supply wells. The Tulare Shallow Aquifer Study Unit includes the Kaweah, Tule, and Tulare Lake subbasins of the San Joaquin Valley groundwater basin and adjacent areas of the Sierra Nevada. The study unit was divided into equal area grid cells and one domestic well was sampled in each cell. Groundwater samples were analyzed for field water-quality parameters, volatile organic compounds, pesticides and pesticide degradates, nutrients, major ions and trace elements, gross alpha and gross beta particle activities, noble gases, tritium, carbon-14 in dissolved inorganic carbon, stable isotopic ratios of water and dissolved nitrate, and microbial indicators.These data support the following publication:Fram, M.S., 2017, Groundwater Quality in the Shallow Aquifers of the Tulare, Kaweah, and Tule Groundwater Basins and Adjacent Highlands areas, Southern San Joaquin Valley, California: U.S. Geological Survey Fact Sheet 2017–3001, 4 p., http://dx.doi.org/10.3133/fs20173001.

  8. Groundwater residence time and aquifer recharge in multilayered, semi-confined and faulted aquifer systems using environmental tracers

    NASA Astrophysics Data System (ADS)

    Batlle-Aguilar, Jordi; Banks, Eddie W.; Batelaan, Okke; Kipfer, Rolf; Brennwald, Matthias S.; Cook, Peter G.

    2017-03-01

    The potential of environmental tracers (δ18O, δ2H, δ13C, 14C, 4He, 20Ne, 40Ar, N2) to assist our understanding of recharge processes, groundwater flow velocities and residence times in semi-confined, multilayered and faulted aquifer systems was tested in a coastal system with Quaternary sediments overlying Tertiary aquifers and fractured bedrock. Carbon-14 groundwater ages were found to increase with depth and distance (<1000 y near the recharge area to >30,000 y near the coast), confirming that the system is semi-confined and the palaeometeoric origin of groundwater as suggested by water stable isotopes. The presence of old groundwater near the top of deep semi-confined aquifers suggests that recharge mainly occurs in the ranges east of the basin. This is also supported by Cl concentrations, which are higher in the overlying Quaternary aquifers. Groundwater flow velocities between 0.3 and 1.8 m y-1 were estimated using 14C ages, resulting in basin recharge estimates between 0.3 × 107 and 2 × 107 m3 y-1. Radiocarbon and 4He-estimated flow velocities were generally in good agreement, although 4He accumulation rates ranging between 8 × 10-12 and 1 × 10-10 cm3 STP g-1 y-1 and 1.7-7.1 × 10-7 cm3 STP g-1 km-1 confirmed slower flow velocities in some areas. These areas could not be captured using 14C. Faults were found to play a paramount role on mixing old fluids rich in salts and 4He, although it was not possible to demonstrate the role of faults in changing flow velocities, this requiring a higher density of sampling points. Our study shows that environmental tracers have potential to study flow processes in semi-confined, faulted, multilayered aquifer systems, provided a high density of sampling points is available.

  9. Subsurface storage of liquids in the Floridan aquifer system in south Florida

    USGS Publications Warehouse

    Meyer, Frederick W.

    1989-01-01

    The Floridan aquifer system in south Florida is composed chiefly of carbonate rocks that range in age from early Miocene to Paleocene. The top of the Floridian aquifer system generally occurs at depths ranging from 500 to 1,000 ft, and the average thickness is about 3,000 ft. It is divided into three general hydrogeologic units that include Upper Floridan aquifer, the middle confining unit, and the Lower Floridan aquifer. Groundwater movement in the Upper Floridan aquifer is generally from the area of highest head in central Florida, eastward to the Straits of Florida, westward to the Gulf of Mexico, and, to a much lesser extent, southward. Injection of nontoxic liquid wastes into deep, saline parts of the Floridan aquifer system as a pollution-control measure began in 1943 with injection of oilfield brine in southwest Florida. Since then, the practice has quickly expanded, and many high capacity municipal and industrial injection wells are now in operation in southeast Florida. The principal use of the Floridan aquifer system in south Florida is for subsurface storage of liquid waste. The Boulder Zone of the Lower Floridan aquifer is extensively used as a receptacle for injected treated municipal wastewater, oilfield brine and, to a lesser extent, industrial wastewater. Pilot studies indicate a potential for cyclic storage of freshwater in the Upper Floridan aquifer in south Florida. (USGS)

  10. Geometric Features For Hydrogeologic Modelling The Gabbro of Beja Aquifer System

    NASA Astrophysics Data System (ADS)

    Duque, J.; Almeida, C.

    The Gabbro of Beja Aquifer System is one of the most important hard rock aquifer in the south Portugal. It is implanted in a NW-SE igneous-metamorphic structure with ofiolític affinities. It is a free aquifer (sometimes with some confinement), with pro- ductivities that can reach 30 l/s. It is also a very shallow aquifer, the deepness mean is about 30 m. The median of groundwater productivity is about 5 L/s. In 1997 it was made the first attempt to characterize the regional groundwater flow through a regional model with MODFLOW. At that time hydrogeological data was scarce and the challenge to define the aquifer geometry was very high and risky. In this aquifer the definition of a model for transport of contaminants MT3D, needs a more accu- rately the definition of the aquifer geometry. With this aim new data is now available, namely almost 1000 borehole log data all over the aquifer. This data will allow the best definition of the geometry of the gabbro of Beja aquifer allowing a more robust definition of the aquifer bottom surface as well as some geological limits, which are very important to the redefinition of the flow and transport model.

  11. Hydrogeological framework of the Edwards-Trinity aquifer system, west-central Texas

    USGS Publications Warehouse

    Barker, Rene A.; Ardis, Ann F.

    1996-01-01

    The Edwards-Trinity aquifer system underlies about 42,000 square miles of west-central Texas, where mostly gently dipping Lower Cretaceous strata comprise three regional aquifers and two regional confining units. The aquifers are the Edwards Aquifer of the Balcones fault zone, the Trinity Aquifer of the Balcones fault zone and Hill County, and the Edwards-Trinity Aquifer of the Edwards Plateau and Trans-Pecos. The Navarro-Del Rio confining unit confines the downdip part of the Edwards Aquifer, and the Hammett confining unit confines the updip, basal part of the Trinity Aquifer and a small southeastern fringe of the Edwards-Trinity Aquifer. Transmissivity averages less than 10,000 feet squared per day throughout more than 90 percent of the study area as the result of widespread cementation and secondary mineral growth. However, in fractured and leached rocks in the Balcones fault zone, transmissivity averages about 750,000 feet squared per day in the Edwards aquifer, which occupies less than 10 percent of the area.

  12. Quantifying spatio-temporal stream-aquifer water exchanges along a multi-layer aquifer system using LOMOS and hydro-thermo modelling

    NASA Astrophysics Data System (ADS)

    Mouhri, Amer; flipo, Nicolas; Rejiba, Fayçal; Bodet, Ludovic; Jost, Anne; Goblet, Patrick

    2014-05-01

    The aim of this work is to understand the spatial and temporal variability of stream-aquifer water exchanges along a 6 km-stream network in a multi-layer aquifer system using both LOcal MOnitoring Stations (LOMOSs) coupled with the optimization of a hydro-thermo model per LOMOS. With an area of 45 km2, the Orgeval experimental basin is located 70 km east from Paris. It drains a multi-layer aquifer system, which is composed of two main geological formations: the Oligocene (upper aquifer unit) and the Eocene (lower aquifer unit). These two aquifer units are separated by a clayey aquitard. The connectivity status between streams and aquifer units has been evaluated using near surface geophysical investigations as well as drill cores. Five LOMOSs of the stream-aquifer exchanges have been deployed along the stream-network to monitor stream-aquifer exchanges over years, based on continuous pressure and temperature measurements (15 min-time step). Each LOMOS is composed of one or two shallow piezometers located 2 to 3 m away from the river edge; one surface water monitoring system; two hyporheic zone temperature profiles located close to each river bank. The five LOMOSs are distributed in two upstream, two intermediate, and one downstream site. The two upstream sites are connected to the upper aquifer unit, and the downstream one is connected to the lower aquifer unit. The 2012-April - 2013-december period of hydrological data are hereafter analyzed. We first focus on the spatial distribution of the stream-aquifer exchanges along the multi-layer aquifer system during the low flow period. Results display an upstream-downstream functional gradient, with upstream gaining stream and downstream losing stream. This spatial distribution is due to the multi-layer nature of the aquifer system, whose lower aquifer unit is depleted. Then it appears that the downstream losing streams temporally switch into gaining ones during extreme hydrological events, while the upstream streams

  13. Geogenic sources of benzene in aquifers used for public supply, California

    USGS Publications Warehouse

    Landon, Matthew K.; Belitz, Kenneth

    2012-01-01

    Statistical evaluation of two large statewide data sets from the California State Water Board's Groundwater Ambient Monitoring and Assessment Program (1973 wells) and the California Department of Public Health (12417 wells) reveals that benzene occurs infrequently (1.7%) and at generally low concentrations (median detected concentration of 0.024 μg/L) in groundwater used for public supply in California. When detected, benzene is more often related to geogenic (45% of detections) than anthropogenic sources (27% of detections). Similar relations are evident for the sum of 17 hydrocarbons analyzed. Benzene occurs most frequently and at the highest concentrations in old, brackish, and reducing groundwater; the detection frequency was 13.0% in groundwater with tritium <1 pCi/L, specific conductance >1600 μS/cm, and anoxic conditions. This groundwater is typically deep (>180 m). Benzene occurs somewhat less frequently in recent, shallow, and reducing groundwater; the detection frequency was 2.6% in groundwater with tritium ≥1 pCi/L, depth <30 m, and anoxic conditions. Evidence for geogenic sources of benzene include: higher concentrations and detection frequencies with increasing well depth, groundwater age, and proximity to oil and gas fields; and higher salinity and lower chloride/iodide ratios in old groundwater with detections of benzene, consistent with interactions with oil-field brines.

  14. Geogenic sources of benzene in aquifers used for public supply, California.

    PubMed

    Landon, Matthew K; Belitz, Kenneth

    2012-08-21

    Statistical evaluation of two large statewide data sets from the California State Water Board's Groundwater Ambient Monitoring and Assessment Program (1973 wells) and the California Department of Public Health (12,417 wells) reveals that benzene occurs infrequently (1.7%) and at generally low concentrations (median detected concentration of 0.024 μg/L) in groundwater used for public supply in California. When detected, benzene is more often related to geogenic (45% of detections) than anthropogenic sources (27% of detections). Similar relations are evident for the sum of 17 hydrocarbons analyzed. Benzene occurs most frequently and at the highest concentrations in old, brackish, and reducing groundwater; the detection frequency was 13.0% in groundwater with tritium <1 pCi/L, specific conductance >1600 μS/cm, and anoxic conditions. This groundwater is typically deep (>180 m). Benzene occurs somewhat less frequently in recent, shallow, and reducing groundwater; the detection frequency was 2.6% in groundwater with tritium ≥1 pCi/L, depth <30 m, and anoxic conditions. Evidence for geogenic sources of benzene include: higher concentrations and detection frequencies with increasing well depth, groundwater age, and proximity to oil and gas fields; and higher salinity and lower chloride/iodide ratios in old groundwater with detections of benzene, consistent with interactions with oil-field brines.

  15. Estimation of transit times in a Karst Aquifer system using environmental tracers: Application on the Jeita Aquifer system-Lebanon.

    NASA Astrophysics Data System (ADS)

    Doummar, Joanna; Hamdan, Ahmad

    2016-04-01

    Estimating transit times is essential for the assessment of aquifer vulnerability to contaminants. Groundwater in karst aquifer is assumed to be relatively young due to fast preferential pathways; slow flow components are present in water stored in the fissured matrix. Furthermore, transit times are site specific as they depend on recharge rates, temperatures, elevation, and flow media; saturated and unsaturated zones. These differences create significant variation in the groundwater age in karst systems as the water sampled will be a mix of different water that has been transported through different flow pathways (fissured matrix and conduits). Several methods can be applied to estimate water transit time of an aquifer such as artificial tracers, which provide an estimate for fast flow velocities. In this study, groundwater residence times in the Jeita spring aquifer (Lebanon) were estimated using several environmental tracers such as Chlorofluorocarbons (CFCs), Sulfur Hexafluoride (SF6), Helium-Tritium (3H, 3H- 3He). Additional stable isotope and major ion analysis was performed to characterize water types. Groundwater samples were collected from six different wells in the Jeita catchment area (Jurassic Kesrouane aquifer) as well as from the spring and cave itself. The results are reproducible for the Tritium-Helium method, unlike for the CFC/SF6 methods that yielded poor results due to sampling problems. Tritium concentrations in all groundwater samples show nearly the same concentration (~2.73 TU) except for one sample with relatively lower tritium concentration (~2.26 TU). Ages ranging from 0.07 ± 0.07 years to 23.59 ± 0.00 years were obtained. The youngest age is attributed to the spring/ cave while the oldest ages were obtained in wells tapping the fissured matrix. Neon in these samples showed considerable variations and high delta Ne in some samples indicating high excess air. Four (4) samples showed extreme excess air (Delta-Ne is greater than 70 %) and

  16. Using Genetic Algorithm and MODFLOW to Characterize Aquifer System of Northwest Florida

    EPA Science Inventory

    By integrating Genetic Algorithm and MODFLOW2005, an optimizing tool is developed to characterize the aquifer system of Region II, Northwest Florida. The history and the newest available observation data of the aquifer system is fitted automatically by using the numerical model c...

  17. Using Genetic Algorithm and MODFLOW to Characterize Aquifer System of Northwest Florida (Published Proceedings)

    EPA Science Inventory

    By integrating Genetic Algorithm and MODFLOW2005, an optimizing tool is developed to characterize the aquifer system of Region II, Northwest Florida. The history and the newest available observation data of the aquifer system is fitted automatically by using the numerical model c...

  18. Processes affecting geochemistry and contaminant movement in the middle Claiborne aquifer of the Mississippi embayment aquifer system

    USGS Publications Warehouse

    Katz, Brian G.; Kingsbury, James A.; Welch, Heather L.; Tollett, Roland W.

    2012-01-01

    Groundwater chemistry and tracer-based age data were used to assess contaminant movement and geochemical processes in the middle Claiborne aquifer (MCA) of the Mississippi embayment aquifer system. Water samples were collected from 30 drinking-water wells (mostly domestic and public supply) and analyzed for nutrients, major ions, pesticides, volatile organic compounds (VOCs), and transient age tracers (chlorofluorocarbons, tritium and helium-3, and sulfur hexafluoride). Redox conditions are highly variable throughout the MCA. However, mostly oxic groundwater with low dissolved solids is more vulnerable to nitrate contamination in the outcrop areas east of the Mississippi River in Mississippi and west Tennessee than in mostly anoxic groundwater in downgradient areas in western parts of the study area. Groundwater in the outcrop area was relatively young (apparent age of less than 40 years) with significantly (p 50 m depth) indicated contaminant movement from shallow parts of the aquifer into deeper oxic zones. Given the persistence of nitrate in young oxic groundwater that was recharged several decades ago, and the lack of a confining unit, the downward movement of young contaminated water may result in higher nitrate concentrations over time in deeper parts of the aquifer containing older oxic water.

  19. Solute geochemistry of the Snake River plain regional aquifer system, Idaho and eastern Oregon

    USGS Publications Warehouse

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

    1987-01-01

    Three geochemical methods were used to determine chemical reactions that control solute concentrations in the Snake River Plain regional aquifer system: (1) calculation of a regional solute balance within the aquifer and of mineralogy in the aquifer framework to identify solute reactions, (2) comparison of thermodynamic mineral saturation indices with plausible solute reactions, and (3) comparison of stable isotope ratios of the groundwater with those in the aquifer framework. The geothermal groundwater system underlying the main aquifer system was examined by calculating thermodynamic mineral saturation indices, stable isotope ratios of geothermal water, geothermometry, and radiocarbon dating. Water budgets, hydrologic arguments, and isotopic analyses for the eastern Snake River Plain aquifer system demonstrate that most, if not all, water is of local meteoric and not juvenile or formation origin. Solute balance, isotopic, mineralogic, and thermodynamic arguments suggest that about 20% of the solutes are derived from reactions with rocks forming the aquifer framework. Solute reactions indicate that calcite and silica are precipitated in the aquifer. Large amounts of sodium and chloride, relative to their concentration in the igneous rock, are being removed from the aquifer. Release of fluids from inclusions in the igneous rocks, and initial flushing of grain boundaries and pores of detrital marine sediments in interbeds are believed to be the source of the sodium chloride. Identification and quantification of reactions controlling solute concentrations in groundwater in the eastern plain indicate that the aquifer is not a large mixing vessel that simply stores and transmits water and solutes but is undergoing diagenesis and is both a source and sink for solutes. Reactions controlling solutes in the western Snake River basin are believed to be similar to those in the eastern basin but the regional geothermal system that underlies the Snake River Plain contains

  20. Summary of ground-water hydrology of the Cambrian-Ordovician aquifer system in the northern Midwest, United States: A in Regional aquifer system analysis

    USGS Publications Warehouse

    Young, H.L.

    1992-01-01

    Development of the aquifer system began in various parts of the northern Midwest in the 1860's and 1870's with the drilling of deep, generally flowing artesian wells near Lake Michigan in eastern Wisconsin and northeastern Illinois and along the valleys of the Mississippi River and its tributaries. Initial heads of 186 and 130 feet above Lake Michigan at Milwaukee and Chicago, respectively, have been reported. Large-scale pumping has produced cones of depression in these two areas, with respective head declines of as much as 375 and 900 feet. Other major pumping centers generally have had much smaller declines. The largest withdrawals from the aquifer system were about 180 million gallons per day in each of the major metropolitan areas of Chicago and Minneapolis-St. Paul (Twin Cities). However, the total decline in head in the St. Peter-Prairie du Chien-Jordan aquifer in the Twin Cities by 1980 was only 90 feet because the aquifer is unconfined. Most of the eastern two-thirds of Iowa, where the aquifer system is tightly confined, is characterized by more than 50 feet of head decline, with 200 feet or more at Mason City and the Quad Cities. Pumpage from the Cambrian-Ordovician aquifer system throughout the study area averaged 683 million gallons per day for the period 1976-80. Results of a transient-model simulation show that recharge increased over predevelopment recharge by 447 million gallons per day. Natural discharge decreased by 99 million gallons per day, and 137 million gallons per day was released from aquifer storage. Mineralization of ground water in the aquifer system increases from slightly mineralized calcium magnesium bicarbonate water in the northern recharge areas, through more mineralized, mixed water types with increased sodium and sulfate, to highly mineralized sodium chloride brines in the deeper parts of the structural basins.

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

    USGS Publications Warehouse

    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

  2. Hydraulic properties of the Madison aquifer system in the western Rapid City area, South Dakota

    USGS Publications Warehouse

    Greene, Earl A.

    1993-01-01

    Available information on hydrogeology, data from borehole geophysical logs, and aquifer tests were used to determine the hydraulic properties of the Madison aquifer. From aquifer-test analysis, transmissivity and storage coefficient were determined for the Minnelusa and Madison aquifers, and vertical hydraulic conductivity (Kv') along with specific storage (Ss') for the Minnelusa confining bed. Borehole geophysical well logs were used to determine the thickness and location of the Minnelusa aquifer, the lower Minnelusa confining bed, and the Madison aquifer within the Madison Limestone. Porosity values determined from quantitative analysis of borehole geophysical well logs were used in analyzing the aquifer-test data. The average porosity at the two aquifer-test sites is about 10 percent in the Minnelusa aquifer, 5 percent in the lower Minnelusa confining bed, and 35 percent in the Madison aquifer. The first aquifer test, which was conducted at Rapid City production well #6, produced measured drawdown in the Minnelusa and Madison aquifers. Neuman and Witherspoon's method of determining the hydraulic properties of leaky two-aquifer systems was used to evaluate the aquifer-test data by assuming the fracture and solution-opening network is equivalent to a porous media. Analysis of the aquifer test for the Minnelusa aquifer yielded a transmissivity value of 12,000 feet squared per day and a storage coefficient of 3 x 10-3. The specific storage of the Minnelusa confining bed was 2 x 10-7 per foot, and its vertical hydraulic conductivity was 0.3 foot per day. The transmissivity of the Madison aquifer at this site was 17,000 feet squared per day, and the storage coefficient was 2 x 10-3. The second aquifer test, which was conducted at Rapid City production well #5 (RC-5) produced measured drawdown only in the Madison aquifer. Hantush and Jacob's method of determining the hydraulic properties of leaky confined aquifers with no storage in the confining bed was used to

  3. Properties and chemical constituents in ground water from the lower Wilcox Aquifer, Mississippi Embayment Aquifer System, south-central United States

    USGS Publications Warehouse

    Pettijohn, Robert A.; Busby, John F.; Beckman, Jeffery D.

    1993-01-01

    The Gulf Coast Regional Aquifer-System Analysis is a study of regional aquifers composed of sediments of mostly Cenozoic age that underlie about 230,000 sq mi of the Gulf Coastal Plain. These regional aquifers are part of three aquifer systems: (1) the Mississippi Embayment Aquifer System, (2) the Texas Coastal Uplands Aquifer System, and (3) the Coastal Lowlands Aquifer System. The water chemistry of the Lower Wilcox Aquifer, which is part of the Mississippi Embayment Aquifer System is presented by a series of maps. These maps show the areal distribution of (1) the concentration of dissolved solids and temperature, (2) the primary water types and pH, (3) the concentration of major ions and silica, and (4) the milliequivalent ratios of selected ions. Dissolved constituents, pH, temperature, and ratios are based on the median values of all samples in each 100-sq-mi area. The concentration of dissolved solids in water from the Lower Wilcox Aquifer ranges from 18 mg/L near the outcrop in western Tennessee to 122,000 mg/L in a down-dip area in southern Mississippi. The primary water type is calcium bicarbonate in the outcrop area and sodium bicarbonate in all other areas of the aquifer within the limits of available data. The concentrations of major ions generally increase from the outcrop area to the down-dip limit of the data in the southern part of the aquifer area east of the Mississippi River. The milliequivalent ratio maps of selected ions in water from the Lower Wilcox Aquifer indicate some trends. The milliequivalent ratio of magnesium plus calcium to bicarbonate ranges from less than 0.1 to 40.4 and generally decreases from outcrop to down-dip limit of the data in the southern part of the aquifer area east of the Mississippi River. The milliequivalent ratio of bicarbonate to chloride ranges from 0.01 in southern Mississippi to 52.3 in northwestern Mississippi. This ratio increases from the outcrop toward the Mississippi River and from north to south in the

  4. Analysis of Aquifer Response, Groundwater Flow, and PlumeEvolution at Site OU 1, Former Fort Ord, California

    SciTech Connect

    Jordan, Preston D.; Oldenburg, Curtis M.; Su, Grace W.

    2005-02-24

    This report presents a continuation from Oldenburg et al. (2002) of analysis of the hydrogeology, In-Situ Permeable Flow Sensor (ISPFS) results, aquifer response, and changes in the trichloroethylene (TCE) groundwater plume at Operational Unit 1 (OU 1) adjacent to the former Fritzsche Army Airfield at the former Fort Ord Army Base, located on Monterey Bay in northern Monterey County. Fuels and solvents were burned on a portion of OU 1 called the Fire Drill Area (FDA) during airport fire suppression training between 1962 and 1985. This activity resulted in soil and groundwater contamination in the unconfined A-aquifer. In the late 1980's, soil excavation and bioremediation were successful in remediating soil contamination at the site. Shortly thereafter, a groundwater pump, treat, and recharge system commenced operation. This system has been largely successful at remediating groundwater contamination at the head of the groundwater plume. However, a trichloroethylene (TCE) groundwater plume extends approximately 3000 ft (900 m) to the northwest away from the FDA. In the analyses presented here, we augment our prior work (Oldenburg et al., 2002) with new information including treatment-system totalizer data, recent water-level and chemistry data, and data collected from new wells to discern trends in contaminant migration and groundwater flow that may be useful for ongoing remediation efforts. Some conclusions from the prior study have been modified based on these new analyses, and these are pointed out clearly in this report.

  5. A groundwater extraction system to control VOCs in a bedrock aquifer

    SciTech Connect

    Wessley, D.J.; Weber, R.H.; Otzelberger, D.G.

    1994-12-31

    Groundwater quality in the bedrock aquifer at a solid waste landfill has been evaluated since 1984. Since that time, several volatile organic compounds (VOCs) have been detected in various bedrock monitoring wells at the site. Continued detection of VOCs in the bedrock aquifer led to an investigation and design of a remediation system to address the contaminated aquifer. This paper discusses the site background, geology, hydrogeology, and landfall characteristics; the methods and results of the landfill monitoring and investigations performed; and the groundwater extraction system which was designed and constructed to control further off-site migration of contaminants in the bedrock aquifer. A groundwater extraction system has been designed in a bedrock aquifer at a closed landfill in Southeastern Wisconsin.

  6. Geology of the surficial aquifer system, Broward County, Florida; lithologic logs

    USGS Publications Warehouse

    Causaras, C.R.

    1985-01-01

    The geologic framework of the surficial aquifer system, of which the Biscayne aquifer is the major component in Broward County, Florida, is presented in eight geologic cross sections. The cross sections are based on detailed lithologic logs of 27 test wells that were drilled, in the summer of 1981, through the sediments overlying the relatively impermeable units of the Hawthorn Formation, of Miocene age. The cross sections show the aquifer system as a wedge-shaped sequence of Cenozoic sediments. The aquifer thickness gradually decreases from more than 400 feet along the coast to about 160 feet in the west and southwest parts of Broward County. The sediments that comprise the aquifer system range in age from Pliocene to Pleistocene and are assigned to the following stratigraphic units from bottom to top: Tamiami Formation, Caloosahatchee Marl, Fort Thompson Formation, Key Largo Limestone, Anastasia Formation, Miami Oolite, and Pamlico Sand. (USGS)

  7. Aquifer systems in the Great Basin region of Nevada, Utah, and adjacent states; a study plan

    USGS Publications Warehouse

    Harrill, James R.; Welch, A.H.; Prudic, D.E.; Thomas, J.M.; Carman, R.L.; Plume, R.W.; Gates, J.S.; Mason, J.L.

    1983-01-01

    The Great Basin Regional Aquifer Study includes about 140,000 square miles in parts of Nevada, Utah, California, Idaho, Oregon , and Arizona within which 240 hydrographic areas occupy structural depressions formed primarily by basin-and-range faulting. The principal aquifers are in basin-fill deposits; however, significant carbonate-rock aquifers underlie much of eastern Nevada and western Utah. In October 1980, the U.S. Geological Survey started a 4-year study to: (1) describe the ground-water systems, (2) analyze the changes that have led to the systems ' present conditions, (3) tie the results of this and previous studies together in a regional analysis, and (4) provide means by which effects of future ground-water development can be estimated. A plan of work is presented that describes the general approach to be taken. It defines the major tasks necessary to meet objectives and defines constraints on the scope of work. The approach has been influenced by the diverse nature of ground water flow systems and the large number of basins. A detailed appraisal of 240 individual areas would require more resources than are available. Consequently, the general approach is to study selected ' typical ' areas and key hydrologic processes. Effort during the first three years will be directed toward describing the regional hydrology, conducting detailed studies of ' type ' areas and studying selected hydrologic processes. Effort during the final year will be directed toward developing a regional analysis of results. Special studies will include evaluation of regional geochemistry , regional hydrogeology, recharge, ground-water discharge, and use of remote sensing. Areas to be studied using ground-water flow models include the regional carbonate-rock province in eastern Nevada and western Utah, six valleys--Las Vegas, Carson, Paradise, Dixie, Smith Creek, and Stagecoach--Nevada, plus Jordan Valley, the Millford area, and Tule Valley in Utah. The results will be presented in a

  8. Geohydrologic systems in Kansas, geohydrology of the Great Plains aquifer system

    USGS Publications Warehouse

    McGovern, Harold E.; Wolf, R.J.

    1993-01-01

    Sedimentary rocks of Late Cambrian through Early Cretaceous age in Kansas are part of a regional flow system of hydraulically connected aquifers and confining units. Future demands for water require that these deeply buried rocks be studied to describe hydrologic properties and ground-water-flow conditions and to provide information that will serve as the basis for decisions concerning the protection and the management of the water resources contained therein, Toward this end, the U.S. Geological Survey, as a part of its Central Midwest Regional Aquifer-System Analysis (CMRASA), began a 5-year hydrologic investigation of this regional flow system in Arkansas, Colorado, Kansas, Missouri, Nebraska, New Mexico, Oklahoma, South Dakota, and Texas (Jorgensen and Signor, 1981).This chapter is one of nine contained in Hydrologic Investigations Atlas HA-722, which present a description of the physical framework (Chapters B-F) and the geohydrology (Chapters G-I} of principal aquifers and confining systems in Upper Cambrian through Lower Cretaceous rocks in Kansas; the stratigraphic relations of these geohydrologic systems are discussed in detail in Chapter A (Wolf and others, 1990). This chapter (G) describes the geohydrology of the Great Plains aquifer system; the physical framework of the Great Plains aquifer system is presented in Chapter B (Spinazola and others, 1992).The maps in this chapter are based on existing data from selected geophysical and lithologic logs, drill-stem tests, water-level measurements, water-quality analyses, and published maps of stratigraphically equivalent units. An index to the geohydrologic data compiled for the CMRASA in Kansas is presented in Spinazola and others (1987). For the most part, data used to construct the maps were collected over many years and do not reflect aquifer conditions for any specific time period.

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

    USGS Publications Warehouse

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

    2014-01-01

    Water-quality data were synthesized to evaluate factors that affect spatial and depth variability in water quality and to assess aquifer vulnerability to contaminants from geologic materials and those of human origin. The quality of shallow groundwater in the alluvial aquifer and shallow bedrock aquifer system has been adversely affected by development of agricultural and urban areas. Land use has altered the pattern and composition of recharge. Increased recharge from irrigation water has mobilized dissolved constituents and increased concentrations in the shallow groundwater. Concentrations of most constituents associated with poor or degraded water quality in shallow groundwater decreased with depth; many of these constituents are not geochemically conservative and are affected by geochemical reactions such as oxidation-reduction reactions. Groundwater age tracers provide additional insight into aquifer vulnerability and help determine if young groundwater of potentially poor quality has migrated to deeper parts of the bedrock aquifers used for drinking-water supply. Age-tracer results were used to group samples into categories of young, mixed, and old groundwater. Groundwater ages transitioned from mostly young in the water-table wells to mostly mixed in the shallowest bedrock aquifer, the Dawson aquifer, to mostly old in the deeper bedrock aquifers. Although the bedrock aquifers are mostly old groundwater of good water quality, several lines of evidence indicate that young, contaminant-bearing recharge has reached shallow to moderate depths in some areas of the bedrock aquifers. The Dawson aquifer is the most vulnerable of the bedrock aquifers to contamination, but results indicate that the older (deeper) bedrock aquifers are also vulnerable to groundwater contamination and that mixing with young recharge has occurred in some areas. Heavy pumping has caused water-level declines in the bedrock aquifers in some parts of the Denver Basin, which has the potential

  10. Carbonate aquifers

    USGS Publications Warehouse

    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.

  11. The role of perched aquifers in hydrological connectivity and biogeochemical processes in vernal pool landscapes, Central Valley, California

    NASA Astrophysics Data System (ADS)

    Cable Rains, Mark; Fogg, Graham E.; Harter, Thomas; Dahlgren, Randy A.; Williamson, Robert J.

    2006-03-01

    Relatively little is known about the role of perched aquifers in hydrological, biogeochemical, and biological processes of vernal pool landscapes. The objectives of this study are to introduce a perched aquifer concept for vernal pool formation and maintenance and to examine the resulting hydrological and biogeochemical phenomena in a representative catchment with three vernal pools connected to one another and to a seasonal stream by swales. A combined hydrometric and geochemical approach was used. Annual rainfall infiltrated but perched on a claypan/duripan, and this perched groundwater flowed downgradient toward the seasonal stream. The upper layer of soil above the claypan/duripan is 0.6 m in thickness in the uplands and 0.1 m in thickness in the vernal pools. Some groundwater flowed through the vernal pools when heads in the perched aquifer exceeded 0.1 m above the claypan/duripan. Perched groundwater discharge accounted for 30-60% of the inflow to the vernal pools during and immediately following storm events. However, most perched groundwater flowed under or around the vernal pools or was recharged by annual rainfall downgradient of the vernal pools. Most of the perched groundwater was discharged to the outlet swale immediately upgradient of the seasonal stream, and most water discharging from the outlet swale to the seasonal stream was perched groundwater that had not flowed through the vernal pools. Therefore, nitrate-nitrogen concentrations were lower (e.g. 0.17 to 0.39 mg l-1) and dissolved organic carbon concentrations were higher (e.g. 5.97 to 3.24 mg l-1) in vernal pool water than in outlet swale water discharging to the seasonal stream. Though the uplands, vernal pools, and seasonal stream are part of a single surface-water and perched groundwater system, the vernal pools apparently play a limited role in controlling landscape-scale water quality.

  12. Computational and Experimental Simulations of Cr(VI) Remediation via In Situ Reduction in an Alluvial Aquifer at Hinkley, California

    NASA Astrophysics Data System (ADS)

    Bobb, C.; Miller, L. G.; Kent, D. B.; Maher, K.

    2015-12-01

    The accumulation of hexavalent chromium (Cr(VI)) in groundwater due to natural and human-induced processes poses a significant health threat as Cr(VI) is both a carcinogen and mutagen. Anthropogenic Cr(VI) contamination has compromised drinking water in the alluvial aquifer underlying the town of Hinkley, CA and extensive in-situ remediation (ISR) is underway to mitigate the threat to residents. ISR capitalizes on the redox sensitivity of chromium by using ethanol to reduce soluble, toxic, Cr(VI) to insoluble and non-hazardous Cr(III). However, the sequence of reduction reactions that occurs within the aquifer is not well understood. Therefore, we use computer-modeled and experimental redox titrations to examine how pH, oxygen supply, mineral surface chemistry, agitation, and microbial activity impact the reduction of Cr(VI) by ethanol. We further use experimental titrations to confirm the validity of our modeled results. Aqueous and gaseous phases are monitored throughout the experiment to track changes in pH, dissolved oxygen, CO2, Mn(II), Fe(II), and SO42-. Aqueous Fe(II) is a dominant control on Cr(VI) reduction; thus the cycling of Fe in the system must be considered. Our modeled results show that reductive dissolution of manganese oxides and Fe(III) (oxy)hydroxides increases pH, making sulfate reduction thermodynamically favorable. Simultaneous Fe(III) and sulfate reduction allows precipitation of iron sulfide minerals, limiting the available Fe(II) to reduce Cr(VI). Computational model results indicate that elevated organic buffer (HEPES, MOPS, EPPS) concentrations are required to maintain pH values below 8.8 where simultaneous reduction of Fe(III) and SO42- during ethanol oxidation becomes thermodynamically favorable. Microbial activity within the aquifer may also play a significant role in the transfer of electrons from ethanol to the terminal electron acceptors.

  13. Conceptualization of groundwater flow of a coastal arid aquifer using isotopic and chemical tools: La Paz, Baja California Sur, Mexico

    NASA Astrophysics Data System (ADS)

    Tamez-Melendez, Carol; Hernández-Antonio, Arturo; Mahlknecht, Jürgen

    2016-04-01

    Groundwater from the La Paz coastal aquifer in Baja California Sur, Mexico, is the main source of drinking water for the local population. Due to its proximity to the coast, sea water intrusion is the main factor of salinization of groundwater. Other geochemical processes also affect the quality of the aquifer threating its vulnerability. Forty-seven samples were analyzed for ion chemistry and isotopes. A hierarchical cluster analysis was performed for a better interpretation resulting in three main groups and proved for geographical correspondence. Deuterium and d18O ranged from -82 to -52.1 and from -11.6 to -7 permil, respectively, showing that the main recharge originates in the Sierra el Novillo, flowing toward SE-NW direction and in accordance to deuterium excess (d) high evaporation effects (d>10‰) are mostly in the middle portion of the study area and in El Centenario due to high kinetic isotope fractioning related to elevated temperatures. Hydrogeochemistry analyses demonstrated salinization mainly due to sea water intrusion and in second instance due water-rock interaction, where enrichment of Na+ (ranges from 35.7 to 1089 mg/L-1) was present in some samples probably due to weathering of silicates and/or cation exchange in soils with Ca2+ (27.7 to 658 mg/L-1) at clay-surfaces. High concentrations of NO3-2 (ranges from 1.4 to 48.8 mg/L-1), Cl- (ranges from 54.4 to 2960 mg/L-1) and Na+ show that anthropogenic input is mainly coming from an agricultural area (El Centenario-Chametla) where heavy groundwater extractions are made for irrigational purposes, lowering the groundwater table up to 10 m and consequently promoting upconing and salinity concentrations (NaCl). Carbon-13 and radiocarbon ranged from -12.3 to -9.1‰ and from 29.5 to 100.4 pmC, respectively. Distribution of ages (up to ~5000 years) indicates two flow trends (E-W and SE-NW).

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

    NASA Astrophysics Data System (ADS)

    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

  15. Predictability of the California Current System

    NASA Technical Reports Server (NTRS)

    Miller, Arthur J.; Chereskin, T.; Cornuelle, B. D.; Niiler, P. P.; Moisan, J. R.; Lindstrom, Eric (Technical Monitor)

    2001-01-01

    The physical and biological oceanography of the Southern California Bight (SCB), a highly productive subregion of the California Current System (CCS) that extends from Point Conception, California, south to Ensenada, Mexico, continues to be extensively studied. For example, the California Cooperative Oceanic Fisheries Investigations (CalCOFI) program has sampled this region for over 50 years, providing an unparalleled time series of physical and biological data. However, our understanding of what physical processes control the large-scale and mesoscale variations in these properties is incomplete. In particular, the non-synoptic and relatively coarse spatial sampling (70km) of the hydrographic grid does not completely resolve the mesoscale eddy field (Figure 1a). Moreover, these unresolved physical variations exert a dominant influence on the evolution of the ecosystem. In recent years, additional datasets that partially sample the SCB have become available. Acoustic Doppler Current Profiler (ADCP) measurements, which now sample upper-ocean velocity between stations, and sea level observations along TOPEX tracks give a more complete picture of the mesoscale variability. However, both TOPEX and ADCP are well-sampled only along the cruise or orbit tracks and coarsely sampled in time and between tracks. Surface Lagrangian drifters also sample the region, although irregularly in time and space. SeaWiFS provides estimates of upper-ocean chlorophyll-a (chl-alpha), usually giving nearly complete coverage for week-long intervals, depending on cloud coverage. Historical ocean color data from the Coastal Zone Color Scanner (CZCS) has been used extensively to determine phytoplankton patterns and variability, characterize the primary production across the SCB coastal fronts, and describe the seasonal and interannual variability in pigment concentrations. As in CalCOFI, these studies described much of the observed structures and their variability over relatively large space and

  16. Water-level surface in the Chicot equivalent aquifer system in southeastern Louisiana, 2009

    USGS Publications Warehouse

    Tomaszewski, Dan J.

    2011-01-01

    The Chicot equivalent aquifer system is an important source of freshwater in southeastern Louisiana. In 2005, about 47 million gallons per day (Mgal/d) were withdrawn from the Chicot equivalent aquifer system in East Baton Rouge, East Feliciana, Livingston, Tangipahoa, St. Helena, St. Tammany, Washington, and West Feliciana Parishes. Concentrated withdrawals exceeded 5 Mgal/d in Bogalusa, the city of Baton Rouge, and in northwestern East Baton Rouge Parish. In the study area, about 30,000 wells screened in the Chicot equivalent aquifer system were registered with the Louisiana Department of Transportation and Development (LaDOTD). These wells were constructed for public-supply, industry, irrigation, and domestic uses. Most of the wells were registered as domestic-use wells and are small-diameter, low-yielding wells. Total withdrawal from the Chicot equivalent aquifer system for domestic use was estimated to be 12 Mgal/d in 2005. This report documents the 2009 water-level surface of the Chicot equivalent aquifer system in southeastern Louisiana. The report also shows differences in water-level measurements for the years 1991 and 2009 at selected sites. Understanding changes and trends in water levels is important for continued use, planning, and management of groundwater resources. The U.S. Geological Survey, in cooperation with the Louisiana Department of Transportation and Development, conducted this study of the water-level surface of the Chicot equivalent aquifer system as part of an ongoing effort to monitor groundwater levels in aquifers in Louisiana.

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

    USGS Publications Warehouse

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

    2013-01-01

    Maps were georeferenced and digitized where existing geographic information system (GIS) data were unavailable (1977–89, 1991, 1995–99). Existing GIS data available for 1990, 1992–94, and 2000–13 were included in the geodatabase. The feature classes were organized into three feature datasets by principal aquifer: Chicot, Evangeline, and Jasper aquifers.

  18. Approximate potentiometric surface for the aquifer unit A3, southeastern coastal plain aquifer system of the United States, prior to development

    USGS Publications Warehouse

    Stricker, V.A.

    1985-01-01

    A generalized potentiometric surface map prepared as part of the southeastern United States, Regional Sand Aquifer-System Analysis defines the altitude of water levels under conditions prior to development for aquifer unit A3, the middle group of aquifers in the sand aquifer system. Aquifer unit A3, consisting of Upper Cretaceous and Tertiary sands, is under artesian conditions except locally in the recharge areas. The regional flow direction is to the rivers in the area where the unit outcrops, west toward the Mississippi River in Mississippi, and southward to the Gulf of Mexico in Alabama and West Georgia. In eastern Georgia, the flow is southeast toward the Atlantic Ocean , and in South Carolina, the direction of flow is southeast toward the Pee Dee River. (USGS)

  19. Summary of hydrologic testing of the Floridan aquifer system at Hunter Army Airfield, Chatham County, Georgia

    USGS Publications Warehouse

    Williams, Lester J.

    2010-01-01

    indicated the Upper Floridan aquifer had a transmissivity of 40,000 feet squared per day, and the Lower Floridan aquifer had a transmissivity of 10,000 feet squared per day. An aquifer test conducted on the combined aquifer system, when the test well was open from 333 to 1,112 feet, gave a transmissivity of 50,000 feet squared per day. Additionally, during the 72-hour test of the Lower Floridan aquifer, a drawdown response was observed in the Upper Floridan aquifer wells.

  20. Hydrogeology and hydrologic conditions of the Ozark Plateaus aquifer system

    USGS Publications Warehouse

    Hays, Phillip D.; Knierim, Katherine J.; Breaker, Brian K.; Westerman, Drew A.; Clark, Brian R.

    2016-11-23

    The hydrogeology and hydrologic characteristics of the Ozark Plateaus aquifer system were characterized as part of ongoing U.S. Geological Survey efforts to assess groundwater availability across the Nation. The need for such a study in the Ozark Plateaus physiographic province (Ozark Plateaus) is highlighted by increasing demand on groundwater resources by the 5.3 million people of the Ozark Plateaus, water-level declines in some areas, and potential impacts of climate change on groundwater availability. The subject study integrates knowledge gained through local investigation within a regional perspective to develop a regional conceptual model of groundwater flow in the Ozark Plateaus aquifer system (Ozark system), a key phase of groundwater availability assessment. The Ozark system extends across much of southern Missouri and northwestern and north-central Arkansas and smaller areas of southeastern Kansas and northeastern Oklahoma. The region is one of the major karst landscapes in the United States, and karst aquifers are predominant in the Ozark system. Groundwater flow is ultimately controlled by aquifer and confining unit lithologies and stratigraphic relations, geologic structure, karst development, and the character of surficial lithologies and regolith mantle. The regolith mantle is a defining element of Ozark Plateaus karst, affecting recharge, karst development, and vulnerability to surface-derived contaminants. Karst development is more advanced—as evidenced by larger springs, hydraulic characteristics, and higher well yields—in the Salem Plateau and in the northern part of the Springfield Plateau (generally north of the Arkansas-Missouri border) as compared with the southern part of the Springfield Plateau in Arkansas, largely due to thinner, less extensive regolith and purer carbonate lithology.Precipitation is the ultimate source of all water to the Ozark system, and the hydrologic budget for the Ozark system includes inputs from recharge

  1. Upper Basalt-Confined Aquifer System in the Southern Hanford Site

    SciTech Connect

    Thorne, P.

    1999-01-04

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

  2. Hydrochemistry and hydrogeologic conditions within the Hanford Site upper basalt confined aquifer system

    SciTech Connect

    Spane, F.A. Jr.; Webber, W.D.

    1995-09-01

    As part of the Hanford Site Ground-Water Surveillance Project, Flow System Characterization Task. Pacific Northwest Laboratory examines the potential for offsite migration of contamination within the upper basalt confined aquifer system for the US Department of Energy (DOE). As part of this activity, groundwater samples were collected over the past 2 years from selected wells completed in the upper Saddle Mountains Basalt. The hydrochemical and isotopic information obtained from these groundwater samples provides hydrologic information concerning the aquifer-flow system. Ideally, when combined with other hydrologic property information, hydrochemical and isotopic data can be used to evaluate the origin and source of groundwater, areal groundwater-flow patterns, residence and groundwater travel time, rock/groundwater reactions, and aquifer intercommunication for the upper basalt confined aquifer system. This report presents the first comprehensive Hanford Site-wide summary of hydrochemical properties for the upper basalt confined aquifer system. This report provides the hydrogeologic characteristics (Section 2.0) and hydrochemical properties (Section 3.0) for groundwater within this system. A detailed description of the range of the identified hydrochemical parameter subgroups for groundwater in the upper basalt confined aquifer system is also presented in Section 3.0. Evidence that is indicative of aquifer contamination/aquifer intercommunication and an assessment of the potential for offsite migration of contaminants in groundwater within the upper basalt aquifer is provided in Section 4.0. The references cited throughout the report are given in Section 5.0. Tables that summarize groundwater sample analysis results for individual test interval/well sites are included in the Appendix.

  3. 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

    USGS Publications Warehouse

    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).

  4. Dynamics of the southern California current system

    NASA Astrophysics Data System (ADS)

    di Lorenzo, Emanuele

    The dynamics of seasonal to long-term variability of the Southern California Current System (SCCS) is studied using a four dimensional space-time analysis of the 52 year (1949--2000) California Cooperative Oceanic Fisheries Investigations (CalCOFI) hydrography combined with a sensitivity analysis of an eddy permitting primitive equation ocean model under various forcing scenarios. The dynamics of the seasonal cycle in the SCCS can be summarized as follows. In spring upwelling favorable winds force an upward tilt of the isopycnals along the coast (equatorward flow). Quasi-linear Rossby waves are excited by the ocean adjustment to the isopycnal displacement. In summer as these waves propagate offshore poleward flow develops at the coast and the Southern California Eddy (SCE) reaches its seasonal maxima. Positive wind stress curl in the Southern California Bight is important in maintaining poleward flow and locally reinforcing the SCE with an additional upward displacement of isopycnals through Ekman pumping. At the end of summer and throughout the fall instability processes within the SCE are a generating mechanism for mesoscale eddies, which fully develop in the offshore waters during winter. On decadal timescales a warming trend in temperature (1 C) and a deepening trend in the depth of the mean thermocline (20 m) between 1950 and 1998 are found to be primarily forced by large-scale decadal fluctuations in surface heat fluxes combined with horizontal advection by the mean currents. After 1998 the surface heat fluxes suggest the beginning of a period of cooling, which is consistent with colder observed ocean temperatures. The temporal and spatial distribution of the warming is coherent over the entire northeast Pacific Ocean. Salinity changes are decoupled from temperature and uncorrelated with indices of large-scale oceanic variability. Temporal modulation of southward horizontal advection by the California Current is the primary mechanism controlling local

  5. Hydraulic response of an unconfined-fractured two-aquifer system driven by dual tidal or stream fluctuations

    NASA Astrophysics Data System (ADS)

    Sedghi, Mohammad M.; Zhan, Hongbin

    2016-11-01

    Many islands consist of limestone sedimentary deposits that are better described as a two-aquifer system consisting of an unconfined aquifer (Quaternary sediments) above a fractured aquifer (fractured limestone) in which groundwater heads are closely regulated by tidal fluctuations on both sides of the islands (dual tides). Propagation of tidal signal, reflected in hydraulic head fluctuation in such a two-aquifer system is significantly different from that in a single aquifer system that is often assumed. The Laplace domain solution of the head fluctuation in such a two-aquifer system subjected to dual tides is obtained first and subsequently inverted to yield real-time solution. Unlike previous solutions, Fourier series with complex variables are avoided and Fourier sine transform is used instead. The solution takes into account an instantaneously drainable water table, hydraulic conductivity anisotropy and arbitrary time-dependent tidal fluctuations. The hydraulic connection of the underlying fractured aquifer and the overlying unconfined aquifer is explored in details. The presented solution can be used to evaluate the head fluctuations and the aquifer parameter estimation of the two-aquifer system underneath a strip-shape island subjected to dual tides. The results can be used to determine the optimum piezometer location to estimate hydraulic parameters of the two-aquifer system using groundwater head fluctuation data. Stream-aquifer interaction is similar to the tidal-aquifer interaction if the chemical difference of the salt water and fresh water is not a concern. The developed solution for tidal-aquifer interaction here can also be used to investigate the aquifer response to stream stage variations in river basin aquifers.

  6. Hydrogeologic framework and geochemistry of the intermediate aquifer system in parts of Charlotte, De Soto, and Sarasota counties, Florida

    USGS Publications Warehouse

    Torres, A.E.; Sacks, L.A.; Yobbi, D.K.; Knochenmus, L.A.; Katz, B.G.

    2001-01-01

    The hydrogeologic framework underlying the 600-square-mile study area in Charlotte, De Soto, and Sarasota Counties, Florida, consists of the surficial aquifer system, the intermediate aquifer system, and the Upper Floridan aquifer. The hydrogeologic framework and the geochemical processes controlling ground-water composition were evaluated for the study area. Particular emphasis was given to the analysis of hydrogeologic and geochemical data for the intermediate aquifer system. Flow regimes are not well understood in the intermediate aquifer system; therefore, hydrogeologic and geochemical information were used to evaluate connections between permeable zones within the intermediate aquifer system and between overlying and underlying aquifer systems. Knowledge of these connections will ultimately help to protect ground-water quality in the intermediate aquifer system. The hydrogeology was interpreted from lithologic and geophysical logs, water levels, hydraulic properties, and water quality from six separate well sites. Water-quality samples were collected from wells located along six ground-water flow paths and finished at different depth intervals. The selection of flow paths was based on current potentiometric-surface maps. Ground-water samples were analyzed for major ions; field parameters (temperature, pH, specific conductance, and alkalinity); stable isotopes (deuterium, oxygen-18, and carbon-13); and radioactive isotopes (tritium and carbon-14). The surficial aquifer system is the uppermost aquifer, is unconfined, relatively thin, and consists of unconsolidated sand, shell, and limestone. The intermediate aquifer system underlies the surficial aquifer system and is composed of clastic sediments interbedded with carbonate rocks. The intermediate aquifer system is divided into three permeable zones, the Tamiami/Peace River zone (PZ1), the Upper Arcadia zone (PZ2), and the Lower Arcadia zone (PZ3). The Tamiami/Peace River zone (PZ1) is the uppermost zone and is

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

    NASA Astrophysics Data System (ADS)

    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 (<10,000 ppm TDS) water in the state. Another is the lack of publically-accessible information about the hydrological properties of confining strata adjacent to injection zones. In effort to better understand these two problems, we have begun studying the archived 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.

  8. Large sedimentary aquifer system and sustainable management: investigations of hydrogeological and geochemical variations in Eocene sand aquifer, south western France

    NASA Astrophysics Data System (ADS)

    Malcuit, E.; Negrel, P. J.; Petelet-Giraud, E.; Durst, P.

    2010-12-01

    In the sedimentary Aquitaine Basin, the Eocene Sand Aquifer system, mostly confined, represents strategic resources for drinking water, irrigation, gas storage and geothermal resources. Therefore, its quantity and quality issues are essential for the sustainable management in this large region that extends over 116,000 km2 (i.e. one-fifth of the French territory). The Eocene Sand Aquifer system comprises at least five aquifers: Paleocene, Eocene infra-molassic sands, early Eocene, middle Eocene, and late Eocene. The extension and thickness of Eocene aquifer layers and negative confined layers vary throughout the basin, from several tens of metres to a hundred metres. The deposit sequences characterizing the Eocene Aquifer System are progradational westward from detrital deposits to carbonates. Eocene sands and Eocene limestones are hydraulically connected and covered by an aquiclude of up to several hundred metres thick of molassic sediments. The groundwater recharge is assumed to occur through the Eocene outcrops located in the north and north-east, and in the south east in contact with the Montagne Noire as well as by vertical leakage from the upper and lower aquifers. Another recharge is suspected in the south near the Petites Pyrenees. According to isotopic data, both present-day recharge and old recharge (16-35 ky) can be evidenced. The north and south evolutions of the piezometric surface are different. In the north, because of years of pumping, a trough in the potentiometric surface has been formed. The piezometric decline is roughly one meter per year in the depression centre. In the south, the decline of the water table is roughly half a meter per year. Furthermore, in the south part, around two sites of gas storage, significant fluctuations of the potentiometric surface are superimposed to the variations resulting from water abstraction, due to the injection and abstraction of gas. However, a major difficulty for the sustainable management is the lack of

  9. Hydrostratigraphic modeling of a complex, glacial-drift aquifer system for importation into MODFLOW.

    PubMed

    Herzog, Beverly L; Larson, David R; Abert, Curtis C; Wilson, Steven D; Roadcap, George S

    2003-01-01

    Deposition from at least three episodes of glaciation left a complex glacial-drift aquifer system in central Illinois. The deepest and largest of these aquifers, the Sankoty-Mahomet Aquifer, occupies the lower part of a buried bedrock valley and supplies water to communities throughout central Illinois. Thin, discontinuous aquifers are present within glacial drift overlying the Sankoty-Mahomet Aquifer. This study was commissioned by local governments to identify possible areas where a regional water supply could be obtained from the aquifer with minimal adverse impacts on existing users. Geologic information from more than 2,200 existing water well logs was supplemented with new data from 28 test borings, water level measurements in 430 wells, and 35 km of surface geophysical profiles. A three-dimensional (3-D) hydrostratigraphic model was developed using a contouring software package, a geographic information system (GIS), and the 3-D geologic modeling package, EarthVision. The hydrostratigraphy of the glacial-drift sequence was depicted as seven uneven and discontinuous layers, which could be viewed from an infinite number of horizontal and vertical slices and as solid models of any layer. Several iterations were required before the 3-D model presented a reasonable depiction of the aquifer system. Layers from the resultant hydrostratigraphic model were imported into MODFLOW, where they were modified into continuous layers. This approach of developing a 3-D hydrostratigraphic model can be applied to other areas where complex aquifer systems are to be modeled and is also useful in helping lay audiences visualize aquifer systems.

  10. Hydrostratigraphic modeling of a complex, glacial-drift aquifer system for importation into MODFLOW

    USGS Publications Warehouse

    Herzog, B.L.; Larson, D.R.; Abert, C.C.; Wilson, S.D.; Roadcap, G.S.

    2003-01-01

    Deposition from at least three episodes of glaciation left a complex glacial-drift aquifer system in central Illinois. The deepest and largest of these aquifers, the Sankoty-Mahomet Aquifer, occupies the lower part of a buried bedrock valley and supplies water to communities throughout central Illinois. Thin, discontinuous aquifers are present within glacial drift overlying the Sankoty-Mahomet Aquifer. This study was commissioned by local governments to identify possible areas where a regional water supply could be obtained from the aquifer with minimal adverse impacts on existing users. Geologic information from more than 2200 existing water well logs was supplemented with new data from 28 test borings, water level measurements in 430 wells, and 35 km of surface geophysical profiles. A three-dimensional (3-D) hydrostratigraphic model was developed using a contouring software package, a geographic information system (GIS), and the 3-D geologic modeling package, EarthVision??. The hydrostratigraphy of the glacial-drift sequence was depicted as seven uneven and discontinuous layers, which could be viewed from an infinite number of horizontal and vertical slices and as solid models of any layer. Several iterations were required before the 3-D model presented a reasonable depiction of the aquifer system. Layers from the resultant hydrostratigraphic model were imported into MODFLOW, where they were modified into continuous layers. This approach of developing a 3-D hydrostratigraphic model can be applied to other areas where complex aquifer systems are to be modeled and is also useful in helping lay audiences visualize aquifer systems.

  11. Factors controlling elevated lead concentrations in water samples from aquifer systems in Florida

    SciTech Connect

    Katz, B.G.; Berndt, M.P.; Bullen, T.D.; Hansard, P.

    1999-07-01

    This report presents results of detailed statistical analyses of total and dissolved Pb concentrations in water samples collected from the major aquifer systems in Florida for the FGWQMN [Florida Ground Water Quality Monitoring Network] to determine the influence of anthropogenic factors on elevated Pb concentrations. In addition, Pb isotopic data are presented for water samples collected from a subset of 13 wells in the monitoring network, samples of aquifer material, rainfall, and Pb counterweights. The Pb-isotope data provide a better understanding of the relative contributions of anthropogenic and natural sources of Pb in ground water samples from Florida`s major aquifer systems.

  12. Hydrogeology of the North Coast Limestone aquifer system of Puerto Rico

    USGS Publications Warehouse

    Rodríguez-Martínez, Jesús

    1995-01-01

    The North Coast Limestone aquifer system of Puerto Rico is composed of three regional hydrogeologic units: an upper aquifer that contains an underlying saltwater zone near the coast, a middle confining unit, and a lower aquifer. The upper aquifer is unconfined, except in coastal areas where it is locally confined by fine-grained surficial deposits. The upper aquifer is mostly absent in the Rio Piedras area of northeastern Puerto Rico. The confining unit is composed of calcareous claystone, marl, chalky and silicified limestone, and locally clayey fine-grained sandstone. Test hole data indicate that the confining unit is locally leaky in the San Juan metropolitan area. An artesian zone of limited areal extent exists within the middle confining unit, in the central part of the study area. The lower aquifer mostly contains ground water under confined conditions except in the outcrop areas, where it is unconfined. The lower aquifer is thickest and most transmissive in the north-central part of the study area. Water in the lower aquifer is fresh throughout much of the area, but is brackish in some areas near San Juan and Guaynabo. West of the Rio Grande de Arecibo, the extent of the lower aquifer is uncertain. Data are insufficient to determine whether or not the existing multiple water-bearing units in this area are an extension of the more productive lower aquifer in the Manati to Arecibo area. Zones of moderate permeability exist within small lenses of volcanic conglomerate and sandstone of the San Sebastian Formation, but in general this formation is not a productive aquifer. Transmissivity values for the upper aquifer range from 200 to more than 280,000 feet squared per day. The transmissivity values for the upper aquifer generally are highest in the area between the Rio de la Plata and Rio Grande de Arecibo, where transmissivity values have been reported to exceed 100,000 feet squared per day in six locations. Transmissivity estimates for the lower aquifer are

  13. Groundwater quality in the shallow aquifers of the Tulare, Kaweah, and Tule Groundwater Basins and adjacent highlands areas, Southern San Joaquin Valley, California

    USGS Publications Warehouse

    Fram, Miranda S.

    2017-01-18

    Groundwater provides more than 40 percent of California’s drinking water. To protect this vital resource, the State of California created the Groundwater Ambient Monitoring and Assessment (GAMA) Program. The Priority Basin Project of the GAMA Program provides a comprehensive assessment of the State’s groundwater quality and increases public access to groundwater-quality information. The shallow aquifers of the Tulare, Kaweah, and Tule groundwater basins and adjacent highlands areas of the southern San Joaquin Valley constitute one of the study units being evaluated.

  14. Recovery of injected freshwater from a brackish aquifer with a multiwell system.

    PubMed

    Miotliński, Konrad; Dillon, Peter J; Pavelic, Paul; Barry, Karen; Kremer, Sarah

    2014-01-01

    Herein we propose a multiple injection and recovery well system strategically operated for freshwater storage in a brackish aquifer. With the system we call aquifer storage transfer and recovery (ASTR) by using four injection and two production wells, we are capable of achieving both high recovery efficiency of injected freshwater and attenuation of contaminants through adequately long residence times and travel distances within the aquifer. The usual aquifer storage and recovery (ASR) scheme, in which a single well is used for injection and recovery, does not warrant consistent treatment of injected water due to the shorter minimum residence times and travel distances. We tested the design and operation of the system over 3 years in a layered heterogeneous limestone aquifer in Salisbury, South Australia. We demonstrate how a combination of detailed aquifer characterization and solute transport modeling can be used to maintain acceptable salinity of recovered water for its intended use along with natural treatment of recharge water. ASTR can be used to reduce treatment costs and take advantage of aquifers with impaired water quality that might locally not be otherwise beneficially used.

  15. Geology of the surficial aquifer system, Dade County, Florida; lithologic logs

    USGS Publications Warehouse

    Causaras, C.R.

    1986-01-01

    The geologic framework of the surficial aquifer system in Dade County, Florida, was investigated as part of a longterm study by the USGS in cooperation with the South Florida Water Management District, to describe the geology, hydrologic characteristics, and groundwater quality of the surficial aquifer system. Thirty-three test wells were drilled completely through the surficial aquifer system and into the underlying, relatively impermeable units of the Tamiami and Hawthorn Formations. Detailed lithologic logs were made from microscopic examination of rock cuttings and cores obtained from these wells. The logs were used to prepare geologic sections that show the lithologic variations, thickness of the lithologic units, and different geologic formations that comprise the aquifers system. (Author 's abstract)

  16. California current system - Predators and the preyscape

    NASA Astrophysics Data System (ADS)

    Ainley, David G.; Adams, Peter B.; Jahncke, Jaime

    2015-06-01

    The preyscape of the California Current System (CCS), one of the most productive marine areas on Earth (Glantz and Thompson, 1981), is highly variable, as evidenced by the papers in this issue, and as such presents a challenge to Ecosystem-based fishery management (EBFM), which attempts to integrate ecosystem considerations as part of fishery management and conservation decisions. Approaches to EBFM for the waters off Washington, Oregon, and California, the CCS, have been initiated (PFMC, 2007, 2013), and are continually being developed. To inform this process, a workshop was held in September 2013 to: i) gather together the existing information on forage fish and predator dynamics in the CCS; ii) consider temporal (seasonal, annual, decadal) and spatial availability of prey complexes and why these patterns of availability occur and change; iii) summarize and present that information for discussion to a large range of experts in oceanography, fish and fisheries management, seabirds, marine mammals, and ecosystem management; and, iv) synthesize this information to be useable by fishery agencies. The papers in this special Journal of Marine Systems issue address these four points. While the full results and recommendations can be found here - "http://www.pointblue.org/uploads/assets/calcurrent/REPORT_Forage_Fish_Workshop_FINAL.pdf"

  17. Integrating hydrogeochemical, hydrogeological, and environmental tracer data to understand groundwater flow for a karstified aquifer system.

    PubMed

    Pavlovskiy, Igor; Selle, Benny

    2015-04-01

    For karstified aquifer systems, numerical models of groundwater flow are difficult to setup and parameterize. However, a system understanding useful for groundwater management may be obtained without applying overly complicated models. In this study, we demonstrate for a karstified carbonate aquifer in south-western Germany that a combination of methods with moderate data requirements can be used to infer flowpaths and transit times of groundwater to production wells.

  18. Hydrogeologic framework of the Willamette Lowland aquifer system, Oregon and Washington

    USGS Publications Warehouse

    Woodward, D.G.; Gannett, Marshall W.; Vaccaro, J.J.

    1998-01-01

    This report summarizes the hydraulic characteristics of the materials that make up the Willamette Lowland aquifer system, ground-water movement in the aquifer system, estimates of ground-water recharge, ground-water quality characteristics, construction and use of cross-sectional numerical ground-water flow models, hydrologic controls on ground-water movement, water budgets and flow paths, and a description and application of a conceptual model.

  19. Geochemistry of the Cambrian-Ordovician aquifer system in the northern midwest, United States

    SciTech Connect

    Siegel, D.I.

    1989-01-01

    The geochemistry of the Cambrian-Ordovician aquifer system was modified during the Pleistocene by large-scale emplacement of glacial meltwater, as indicated by large-scale emplacement of glacial meltwater, as indicated by the investigation of stable isotopes of water, and a plume of dilute water that trends perpendicular to the direction of ground-water flow in Iowa and Missouri. Ground water in this part of the aquifer system could be hundreds of thousands of years old.

  20. Characterization of flow dynamics and vulnerability in a coastal aquifer system.

    PubMed

    Murgulet, Dorina; Tick, Geoffrey R

    2013-01-01

    Traditional aquifer vulnerability techniques primarily rely on spatial property data for a region and are limited by their ability to directly or indirectly assess flow and transport processes occurring from the surface to depth within an aquifer system. The main objective of this study was to investigate groundwater vulnerability in terms of aquifer interconnectivity and flow dynamics. A combination of stable isotopes, groundwater age-dating (radiocarbon), and geomorphic/geogenic spatial analyses was applied to a regional, highly developed coastal aquifer to explain the presence of nitrate at depth. The average δ(13) C value (-17.3 ± 2‰ VPDB, n = 27) is characteristic of groundwater originating from locally infiltrated precipitation through extensively cultivated soils. The average δ(18) O and δD values (-4.0 ± 0.1‰ VSMOW, n = 27; δD: -19.3 ± 1‰ VSMOW, n = 27, respectively) are similar to precipitation water derived from maritime sources feeding the region's surface water and groundwater. Stable and radioactive isotopes reveal significant mixing between shallow and deep aquifers due to high velocities, hydraulic connection, and input of local recharge water to depths. Groundwater overdevelopment enhances deeper and faster modern water downward flux, amplifying aquifer vulnerability. Therefore, aquifer vulnerability is a variable, dependent on the type and degree of stress conditions experienced by a groundwater system as well as the geospatial properties at the near surface.

  1. Environmental assessment of the potential effects of aquifer thermal energy storage systems on microorganisms in groundwater

    SciTech Connect

    Hicks, R.J.; Stewart, D.L.

    1988-03-01

    The primary objective of this study was to evaluate the potential environmental effects (both adverse and beneficials) of aquifer thermal energy storage (ATES) technology pertaining to microbial communities indigenous to subsurface environments (i.e., aquifers) and the propagation, movement, and potential release of pathogenic microorganisms (specifically, Legionella) within ATES systems. Seasonal storage of thermal energy in aquifers shows great promise to reduce peak demand; reduce electric utility load problems; contribute to establishing favorable economics for district heating and cooling systems; and reduce pollution from extraction, refining, and combustion of fossil fuels. However, concerns that the widespread implementation of this technology may have adverse effects on biological systems indigeneous to aquifers, as well as help to propagate and release pathogenic organisms that enter thee environments need to be resolved. 101 refs., 2 tabs.

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

    USGS Publications Warehouse

    Mularoni, R.A.

    1994-01-01

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

  3. System Description and Status Report: California Education Information System.

    ERIC Educational Resources Information Center

    California State Dept. of Education, Sacramento.

    The California Education Information System (CEIS) consists of two subsystems of computer programs designed to process business and pupil data for local school districts. Creating and maintaining records concerning the students in the schools, the pupil subsystem provides for a central repository of school district identification information and a…

  4. Analysis of an anisotropic coastal aquifer system using variable-density flow and solute transport simulation

    USGS Publications Warehouse

    Souza, W.R.; Voss, C.I.

    1987-01-01

    The groundwater system in southern Oahu, Hawaii consists of a thick, areally extensive freshwater lens overlying a zone of transition to a thick saltwater body. This system is analyzed in cross section with a variable-density groundwater flow and solute transport model on a regional scale. The simulation is difficult, because the coastal aquifer system has a saltwater transition zone that is broadly dispersed near the discharge area, but is very sharply defined inland. Steady-state simulation analysis of the transition zone in the layered basalt aquifer of southern Oahu indicates that a small transverse dispersivity is characteristic of horizontal regional flow. Further, in this system flow is generally parallel to isochlors and steady-state behavior is insensitive to the longitudinal dispersivity. Parameter analysis identifies that only six parameters control the complex hydraulics of the system: horizontal and vertical hydraulic conductivity of the basalt aquifer; hydraulic conductivity of the confining "caprock" layer; leakance below the caprock; specific yield; and aquifer matrix compressibility. The best-fitting models indicate the horizontal hydraulic conductivity is significantly greater than the vertical hydraulic conductivity. These models give values for specific yield and aquifer compressibility which imply a considerable degree of compressive storage in the water table aquifer. ?? 1987.

  5. A critical evaluation of combined engineered and aquifer treatment systems in water recycling.

    PubMed

    Dillon, P; Page, D; Vanderzalm, J; Pavelic, P; Toze, S; Bekele, E; Sidhu, J; Prommer, H; Higginson, S; Regel, R; Rinck-Pfeiffer, S; Purdie, M; Pitman, C; Wintgens, T

    2008-01-01

    Australian experience at five research sites where stormwater and reclaimed water have been stored in aquifers prior to reuse, have yielded valuable information about water treatment processes in anaerobic and aerobic aquifers. One of these sites is the stormwater to potable water ASTR project at the City of Salisbury, a demonstration project within the broader EC project 'RECLAIM WATER'. A framework for characterising the effectiveness of such treatment for selected organic chemicals, natural organic matter, and pathogens is being developed for inclusion in new Australian Guidelines for Management of Aquifer Recharge. The combination of pre-treatments (including passive systems such as reed beds) and aquifer treatment effectiveness in relation to source waters and intended uses of recovered water will be described. Advantages and disadvantages of various types of pre-treatments in relation to effectiveness and sustainability of managed aquifer recharge will be discussed taking account of aquifer characteristics. These observations will be consolidated into a draft set of principles to assist in selection of engineered treatments compatible with passive treatment in aquifers.

  6. Hydrology of aquifer systems in the Memphis area, Tennessee

    USGS Publications Warehouse

    Criner, James H.; Sun, P-C. P.; Nyman, Dale J.

    1964-01-01

    The Memphis area as described in .this report comprises about 1,300 square miles of the Mississippi embayment part of the Gulf Coastal Plain. The area is underlain by as much as 3,000 feet of sediments ranging in age from Cretaceous through Quaternary. In 1960, 150 mgd (million gallons per day) of water was pumped from the principal aquifers. Municipal pumpage accounted for almost half of this amount, and industrial pumpage a little more than half. About 90 percent of the water used in the area is derived from the '500-foot' sand, and most of the remainder is from the ?400-foot' sand; both sands are of Eocene age. A small amount of water for domestic use is pumped from the terrace deposits of Pliocene and Pleistocene age. Both the '500-foot' and the '1,400-foot' sands are artesian aquifers except in the southeastern part of the area; there the water level in wells in the '500-foot' sand is now below the overlying confining clay. Water levels in both aquifers have declined almost continuously since pumping began, but the rate of decline has increased rapidly since 1940. Water-level decline in the '1,400-foot' sand has been less pronounced since 1956. The cones of depression in both aquifers have expanded and deepened as a result of the annual increases in pumping, and an increase in hydraulic gradients has induced a greater flow of water into the area. Approximately 135 mgd entered the Memphis area through the '500-foot' sand aquifer in 1960, and, of this amount, 60 mgd originated as inflow from the east and about 75 mgd was derived from leakage from the terrace deposits, from the north, south, and west and from other sources. Of the water entering the '1,400-foot' sand, about 5 mgd was inflow from the east, and about half that amount was from each of the north, south, and west directions. The average rate of movement of water outside the area of heavy withdrawals is about 70 feet per year in the '500-foot' sand and about 40 feet per year in the '1,400-foot' sand

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

    USGS Publications Warehouse

    Reese, Ronald S.; Cunningham, Kevin J.

    2014-01-01

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

  8. Bibliography on ground water in glacial-aquifer systems in the Northeastern United States

    USGS Publications Warehouse

    Wiltshire, Denise A.; Lyford, Forest P.; Cohen, A.J.

    1986-01-01

    The U.S. Geological Survey established the Regional Aquifer-System Analysis (RASA) program to evaluate major interconnected aquifers or groups of aquifers that share similar characteristics within a region. One of the objectives of the Northeastern Glacial RASA is to provide information on the occurrence and quality of ground water in glacial deposits in ten States: Maine, New Hampshire, Vermont, Massachusetts, Rhode Island, Connecticut, New York, Ohio, Pennsylvania, and New Jersey. To help meet the objectives of the RASA program, an automated bibliographic data base was developed. The data base contains references to ground-water resources of glacial-aquifer systems in the ten States listed above. This bibliography contains more than 700 ground-water related references that date from 1839 through 1984. The bibliography lists books, journal articles, conference proceedings, government and other technical reports, theses, and maps. Unpublished manuscripts, publications in press, newspaper articles, and book reviews are omitted from the bibliography.

  9. Hydrogeologic Framework of the Yakima River Basin Aquifer System, Washington

    USGS Publications Warehouse

    Vaccaro, J.J.; Jones, M.A.; Ely, D.M.; Keys, M.E.; Olsen, T.D.; Welch, W.B.; Cox, S.E.

    2009-01-01

    The Yakima River basin aquifer system underlies about 6,200 square miles in south-central Washington. The aquifer system consists of basin-fill deposits occurring in six structural-sedimentary basins, the Columbia River Basalt Group (CRBG), and generally older bedrock. The basin-fill deposits were divided into 19 hydrogeologic units, the CRBG was divided into three units separated by two interbed units, and the bedrock was divided into four units (the Paleozoic, the Mesozoic, the Tertiary, and the Quaternary bedrock units). The thickness of the basin-fill units and the depth to the top of each unit and interbed of the CRBG were mapped. Only the surficial extent of the bedrock units was mapped due to insufficient data. Average mapped thickness of the different units ranged from 10 to 600 feet. Lateral hydraulic conductivity (Kh) of the units varies widely indicating the heterogeneity of the aquifer system. Average or effective Kh values of the water-producing zones of the basin-fill units are on the order of 1 to 800 ft/d and are about 1 to 10 ft/d for the CRBG units as a whole. Effective or average Kh values for the different rock types of the Paleozoic, Mesozoic, and Tertiary units appear to be about 0.0001 to 3 ft/d. The more permeable Quaternary bedrock unit may have Kh values that range from 1 to 7,000 ft/d. Vertical hydraulic conductivity (Kv) of the units is largely unknown. Kv values have been estimated to range from about 0.009 to 2 ft/d for the basin-fill units and Kv values for the clay-to-shale parts of the units may be as small as 10-10 to 10-7 ft/d. Reported Kv values for the CRBG units ranged from 4x10-7 to 4 ft/d. Variations in the concentrations of geochemical solutes and the concentrations and ratios of the isotopes of hydrogen, oxygen, and carbon in groundwater provided information on the hydrogeologic framework and groundwater movement. Stable isotope ratios of water (deuterium and oxygen-18) indicated dispersed sources of groundwater recharge to

  10. Glacial aquifer systems in the northeastern United States; a plan for study

    USGS Publications Warehouse

    Lyford, F.P.; Dysart, J.E.; Randall, A.D.; Kontis, A.L.

    1984-01-01

    The U.S. Geological Survey project designed to study the availability and quality of water in glacial aquifers in the States of Maine, New Hampshire, Vermont, Massachusetts, Rhode Island, Connecticut, New York, New Jersey, Pennsylvania, and Ohio is scheduled for completion in 1986. It will focus on general principles that define aquifer geometry, hydraulic properties of sediments, recharge, discharge, physical-chemical properties of water, rock and water-rock interactions, and mechanisms for mixing of water from multiple sources. Planned project activities include compilation and analysis of available data for a regionwide analysis of glacial-aquifer systems, studies of selected system components such as recharge and chemical processes, classification of aquifers with regard to water-supply potential, and construction of generalized ground-water models to predict responses of types of aquifer systems to pumping and climatic stress. This report describes the general characteristics of glacial aquifer systems in the Northeastern United States and of planned work elements of the study. (USGS)

  11. Hydrogeology and water quality of the Floridan aquifer system and effects of Lower Floridan aquifer pumping on the Upper Floridan aquifer at Fort Stewart, Georgia

    USGS Publications Warehouse

    Clarke, John S.; Cherry, Gregory C.; Gonthier, Gerard J.

    2011-01-01

    Test drilling, field investigations, and digital modeling were completed at Fort Stewart, GA, during 2009?2010, to assess the geologic, hydraulic, and water-quality characteristics of the Floridan aquifer system and evaluate the effect of Lower Floridan aquifer (LFA) pumping on the Upper Floridan aquifer (UFA). This work was performed pursuant to the Georgia Environmental Protection Division interim permitting strategy for new wells completed in the LFA that requires simulation to (1) quantify pumping-induced aquifer leakage from the UFA to LFA, and (2) identify the equivalent rate of UFA pumping that would produce the same maximum drawdown in the UFA that anticipated pumping from LFA well would induce. Field investigation activities included (1) constructing a 1,300-foot (ft) test boring and well completed in the LFA (well 33P028), (2) constructing an observation well in the UFA (well 33P029), (3) collecting drill cuttings and borehole geophysical logs, (4) collecting core samples for analysis of vertical hydraulic conductivity and porosity, (5) conducting flowmeter and packer tests in the open borehole within the UFA and LFA, (6) collecting depth-integrated water samples to assess basic ionic chemistry of various water-bearing zones, and (7) conducting aquifer tests in new LFA and UFA wells to determine hydraulic properties and assess interaquifer leakage. Using data collected at the site and in nearby areas, model simulation was used to assess the effects of LFA pumping on the UFA. Borehole-geophysical and flowmeter data indicate the LFA at Fort Stewart consists of limestone and dolomitic limestone between depths of 912 and 1,250 ft. Flowmeter data indicate the presence of three permeable zones at depth intervals of 912-947, 1,090-1,139, and 1,211?1,250 ft. LFA well 33P028 received 50 percent of the pumped volume from the uppermost permeable zone, and about 18 and 32 percent of the pumped volume from the middle and lowest permeable zones, respectively. Chemical

  12. Simulation of ground-water flow in the coastal plain aquifer system of North Carolina

    USGS Publications Warehouse

    Giese, G.L.; Eimers, J.L.; Coble, R.W.

    1991-01-01

    A 3-D finite difference digital model was used to simulate groundwater flow in the 25,000 sq mi aquifer system of the North Carolina Coastal Plain. The model was developed from a geohydrologic framework that is based on an alternating sequence of 10 aquifers and 9 confining units, which comprise a seaward-thickening wedge of sediments that form the Coastal Plain aquifer system in North Carolina. The model was calibrated by comparing observed and simulated water levels. The maximum transmissivity of an individual aquifer in the calibrated model is 200,000 sq ft/d in a part of the Castle Hayne aquifer, which is composed predominately of limestone. The maximum simulated vertical hydraulic conductivity in a confining unit was 2.5 ft/d in a part of the confining unit overlying the upper Cape Fear aquifer. Analysis indicated the model is highly sensitive to changes in transmissivity and leakage near pumping centers; away from pumping centers, the model is only slightly sensitive to changes in transmissivity but is moderately sensitive to changes in leakance. Recharge from precipitation to the surficial aquifer ranges from about 12 in/yr in areas having clay at the surface, to about 20 in/yr in areas having sand at the surface. Most of this recharge moves laterally to streams, with only about 1 in/yr moving down to the confined parts of the aquifer system. Groundwater level declines, which are the result of water taken from storage, are extensive in some area and minimal in others. Water level declines exceeding 100 ft have occurred in the Beaufort County area because of withdrawals for a mining operation and water supplies for a chemical plant. Head declines have been less than 10 ft in the shallow surficial and Yorktown aquifers and in the updip parts of the major confined aquifers distant from areas of major withdrawals. A water-budget analysis using the model simulations indicates that much of the water removed from the groundwater system by pumping ultimately is made

  13. Framework for regional synthesis of water-quality data for the glacial aquifer system in the United States

    USGS Publications Warehouse

    Warner, Kelly L.; Arnold, Terri L.

    2005-01-01

    The glacial aquifer system is the largest principal aquifer in aerial extent and ground-water use for public supply in the United States. A principal aquifer is defined as a regionally extensive aquifer or aquifer system that has the potential to be used as a source of potable water (U.S. Geological Survey, 2003). Multiple aquifers often are grouped into large, extensive aquifer systems such as the glacial aquifer system. The glacial aquifer system is considered here to include all unconsolidated aquifers above bedrock north of the line of continental glaciation throughout the country (fig. 1). Total withdrawals from the glacial aquifer system were 3,560 million gallons per day in 2000, which constitutes almost 5 percent of total withdrawals from all aquifers in the United States (Maupin and Barber, 2005). Approximately 41 million people relied on the glacial aquifer for public supply and domestic use in 2000. The U.S. Geological Survey National Water-Quality Assessment (NAWQA) Program began assessing the glacial aquifer system in 1991. The assessment of water-quality data on a regional scale, such as the glacial aquifer system, is coincident with the regional framework established by the Regional Aquifer-System Analysis Program (RASA) (Sun and others, 1997). From 1978 to 1995, the RASA Program systematically evaluated 25 of the Nation's most important groundwater systems including studies in the glacial aquifer system in the northeast, Midwest, and northern Midwest United States. The NAWQA Program is building on the work of the RASA Program to study the water quality of 16 of the most important ground-water systems (Lapham and others, 2005). Over 1,700 water-quality samples have been collected by the NAWQA Program from 1991 to 2004 to assess the glacial aquifer system. This large data set is unique in that the samples have been collected using a consistent sampling protocol, and multiple nested samples. The nested samples address the recently recharged shallow

  14. Factors controlling elevated lead concentrations in water samples from aquifer systems in Florida

    USGS Publications Warehouse

    Katz, B.G.; Bullen, M.P.; Bullen, T.D.; Hansard, Paul

    1999-01-01

    Concentrations of total lead (Pb) and dissolved Pb exceeded the U.S. Environmental Protection Agency action level of 15 micrograms per liter (mg/L) in approximately 19 percent and 1.3 percent, respectively, of ground-water samples collected during 1991-96 from a statewide network of monitoring wells designed to delineate background water quality of Florida's major aquifer systems. Differences in total Pb concentrations among aquifer systems reflect the combined influence of anthropogenic sources and chemical conditions in each system. A highly significant (p<0.001) difference in median total Pb concentrations was found for water samples from wells with water-level recording devices that contain Pb-counterweights (14 mg/L) compared to non-recorder wells (2 mg/L). Differences between total Pb concentrations for recorder and non-recorder wells are even more pronounced when compared for each aquifer system. The largest differences for recorder status are found for the surficial aquifer system, where median total Pb concentrations are 44 and 2.4 mg/L for recorder wells and non-recorder wells, respectively. Leaching of Pb from metal casing materials is another potential source of Pb in ground water samples. Median total Pb concentrations in water samples from the surficial, intermediate, and Floridan aquifer systems are higher from recorder wells cased with black iron than for recorder wells with steel and PVC casing material. Stable isotopes of Pb were used in this study to distinguish between anthropogenic and natural sources of Pb in ground water, as Pb retains the isotopic signature of the source from which it is derived. Based on similarities between slopes and intercepts of trend lines for various sample types (plots of 206Pb/204Pb versus 208Pb/204Pb and 207Pb/204Pb versus 208Pb/204Pb) the predominant source of total Pb in water samples from the surficial aquifer system is corrosion of Pb counterweights. It is likely that only ground-water samples, not the aquifer

  15. Redox processes and water quality of selected principal aquifer systems

    USGS Publications Warehouse

    McMahon, P.B.; Chapelle, F.H.

    2008-01-01

    Reduction/oxidation (redox) conditions in 15 principal aquifer (PA) systems of the United States, and their impact on several water quality issues, were assessed from a large data base collected by the National Water-Quality Assessment Program of the USGS. The logic of these assessments was based on the observed ecological succession of electron acceptors such as dissolved oxygen, nitrate, and sulfate and threshold concentrations of these substrates needed to support active microbial metabolism. Similarly, the utilization of solid-phase electron acceptors such as Mn(IV) and Fe(III) is indicated by the production of dissolved manganese and iron. An internally consistent set of threshold concentration criteria was developed and applied to a large data set of 1692 water samples from the PAs to assess ambient redox conditions. The indicated redox conditions then were related to the occurrence of selected natural (arsenic) and anthropogenic (nitrate and volatile organic compounds) contaminants in ground water. For the natural and anthropogenic contaminants assessed in this study, considering redox conditions as defined by this framework of redox indicator species and threshold concentrations explained many water quality trends observed at a regional scale. An important finding of this study was that samples indicating mixed redox processes provide information on redox heterogeneity that is useful for assessing common water quality issues. Given the interpretive power of the redox framework and given that it is relatively inexpensive and easy to measure the chemical parameters included in the framework, those parameters should be included in routine water quality monitoring programs whenever possible.

  16. Surficial aquifer system in eastern Lee County, Florida

    USGS Publications Warehouse

    Boggess, D.H.; Watkins, F.A.

    1986-01-01

    The surficial aquifer system in eastern Lee County consists of an upper water bearing unit, which is generally unconfined, and a lower water bearing unit, which is confined and is the major source tapped by most wells. The top of the lower unit, which is of primary interest in this report, ranges in depth from 40 to 60 ft below land surface in the east-central part of the county to more than 120 ft in the southern part. In the extreme southern part of the county, a middle water bearing unit also contains water under artesian pressure. Recharge to the lower unit occurs primarily by leakage from the overlying saturated section through the confining beds. Water levels in the lower unit fluctuate similarly to those in the upper (unconfined) unit. Groundwater in the lower unit moves from areas of highest water level in the south part of Lehigh acres, northward toward the Caloosahatchee River, and toward the coast. The lower unit contains freshwater throughout much of its extent and is the source of public water supply at Lehigh Acres and Green Meadows where an average of about 3 mil gal/day was withdrawn in 1980. In several areas, the concentrations of chlorides and dissolved solids exceed drinking water standards. Yields of wells that tap the lower unit range from 10 to 1,100 gal/min. Transmissivities ranging from about 17,700 to 7,750 sq ft/day were determined for different areas of the unit. Storage coefficients range from 0.0001 to 0.0003. (Author 's abstract)

  17. Summary of hydrologic testing of the Floridan aquifer system at Fort Stewart, Georgia

    USGS Publications Warehouse

    Gonthier, Gerard J.

    2011-01-01

    Flowmeter surveys at the study site indicate several permeable zones within the Floridan aquifer system. The Upper Floridan aquifer is composed of two water-bearing zones-the upper zone and the lower zone. The upper zone extends from 520 to 650 feet below land surface, contributes 96 percent of the total flow, and is more permeable than the lower zone, which extends from 650 to 705 feet below land surface and contributes the remaining 4 percent of the flow. The Lower Floridan aquifer consists of three zones at depths of 912-947, 1,090-1,139, and 1,211-1,250 feet below land surface that are inter-layered with three less-permeable zones. The Lower Floridan confining unit includes a permeable zone that extends from 793 to 822 feet below land surface. Horizontal hydraulic conductivity values of the Lower Floridan confining unit derived from slug tests within four packer-isolated intervals were from 2 to 20 feet per day, with a high value of 70 feet per day obtained for one of the intervals. Aquifer testing, using analytical techniques and model simulation, indicated the Upper Floridan aquifer had a transmissivity of about 100,000 feet squared per day, and the Lower Floridan aquifer had a transmissivity of 7,000 feet squared per day. Flowmeter surveys, slug tests within packer-isolated intervals, and parameter-estimation results indicate that the hydraulic properties of the Lower Floridan confining unit are similar to those of the Lower Floridan aquifer. Water-level data, for each aquifer test, were filtered for external influences such as barometric pressure, earth-tide effects, and long-term trends to enable detection of small water-level responses to aquifer-test pumping of less than 1 foot. During a 72-hour aquifer test of the Lower Floridan aquifer, a drawdown response of 0.3 to 0.4 foot was observed in two Upper Floridan aquifer wells, one of which was more than 1 mile away from the pumped well.

  18. Low velocity non-Darcian flow to a well fully penetrating a confined aquifer in the first kind of leaky aquifer system

    NASA Astrophysics Data System (ADS)

    Meng, Xianmeng; Shao, Junyu; Yin, Maosheng; Liu, Dengfeng; Xue, Xianwu

    2015-11-01

    In this study, we use a finite difference method to solve low velocity non-Darcian flow to a well in the first kind of leaky aquifer system. Flow in the confined aquifer is assumed to be Darcian and horizontal, whereas flow in the aquitard is assumed to be non-Darcian and vertical. The threshold hydraulic gradient existence of non-Darcian flow in low permeability porous media is employed to describe the non-Darcian flow in the aquitard. A numerical solution has been obtained by using a finite difference method. This solution is compared with the previous solution for Darcian flow case in leaky aquifer system. The error has been analyzed. The comparison of this study and Darcian flow case (Hantush and Jacob, 1955) in leaky aquifer system indicates that the error is very small and can be neglected. However, the hydrogeological parameter calculation of leaky aquifer system is remarkably influenced by low velocity non-Darcian flow in aquitard. For the inflection point method (Hantush, 1956), the absolute values of estimated errors for coefficient of transmissibility of confined aquifer and vertical hydraulic conductivity of aquitard show negative relationship with the pumping rate. For the type curve-fitting method (Walton, 1962), the estimated errors for coefficient of transmissibility and elastic drainable porosity of confined aquifer are very small under small pumping rate. In general, the estimated errors for coefficient of transmissibility and elastic drainable porosity of confined aquifer can be controlled under certain level through adjusting pumping rate. The estimated error of vertical hydraulic conductivity of aquitard is quite large no matter which method is used, even up to nearly 300%.

  19. Potentiometric map of the Sparta aquifer system in Mississippi, fall, 1980

    USGS Publications Warehouse

    Wasson, B.E.

    1980-01-01

    This potentiometric map of the Sparta aquifer system is the tenth in a series of maps, prepared by the U.S. Geological Survey in cooperation with the Mississippi Department of Natural Resources, Bureau of Land and Water Resources, delineating the potentiometric surfaces of the major aquifers in Mississippi. In the outcrop area of the Sparta, the potentiometric surface is strongly affected by recharge from precipitation, by topography, and by drainage of the aquifer into streams. The potentiometric surface slopes downward generally to the west away from the area of outcrop and is strongly affected by large ground-water withdrawals in the Jackson, Yazoo City, Cleveland, Clarksdale, and Memphis areas. Historically, water levels in or near the outcrop of the Sparta have shown little or no long-term changes, but during the past 20 years, in much of the confined part of the aquifer, water levels have declined from 1 to 3 feet per year. (USGS)

  20. Three-dimensional conceptual model for the Hanford Site unconfined aquifer system: FY 1994 status report

    SciTech Connect

    Thorne, P.D.; Chamness, M.A.; Vermeul, V.R.; Macdonald, Q.C.; Schubert, S.E.

    1994-11-01

    This report documents work conducted during the fiscal year 1994 to development an improved three-dimensional conceptual model of ground-water flow in the unconfined aquifer system across the Hanford Site Ground-Water Surveillance Project, which is managed by Pacific Northwest Laboratory. The main objective of the ongoing effort to develop an improved conceptual model of ground-water flow is to provide the basis for improved numerical report models that will be capable of accurately predicting the movement of radioactive and chemical contaminant plumes in the aquifer beneath Hanford. More accurate ground-water flow models will also be useful in assessing the impacts of changes in facilities and operations. For example, decreasing volumes of operational waste-water discharge are resulting in a declining water table in parts of the unconfined aquifer. In addition to supporting numerical modeling, the conceptual model also provides a qualitative understanding of the movement of ground water and contaminants in the aquifer.

  1. Descriptive analysis of aquifer thermal energy storage systems

    SciTech Connect

    Reilly, R.W.

    1980-06-01

    The technical and economic feasibility of large-scale aquifer thermal energy storage (ATES) was examined. A key to ATESs attractiveness is its simplicity of design and construction. The storage device consists of two ordinary water wells drilled into an aquifer, connected at the surface by piping and a heat exchanger. During the storage cycle water is pumped out of the aquifer, through the heat exchanger to absorb thermal energy, and then back down into the aquifer through the second well. The thermal storage remains in the aquifer storage bubble until required for use, when it is recovered by reversing the storage operation. For many applications the installation can probably be designed and constructed using existing site-specific information and modern well-drilling techniques. The potential for cost-effective implementation of ATES was investigated in the Twin Cities District Heating-Cogeneration Study in Minnesota. In the study, ATES demonstrated a net energy saving of 32% over the nonstorage scenario, with an annual energy cost saving of $31 million. Discounting these savings over the life of the project, the authors found that the break-even capital cost for ATES construction was $76/kW thermal, far above the estimated ATES development cost of $23 to 50/kW thermal. It appears tht ATES can be highly cost effective as well as achieve substantial fuel savings. ATES would be environmentally beneficial and could be used in many parts of the USA. The existing body of information on ATES indicates that it is a cost-effective, fuel-conserving technique for providing thermal energy for residential, commercial, and industrial users. The negative aspects are minor and highly site-specific, and do not seem to pose a threat to widespread commercialization. With a suitable institutional framework, ATES promises to supply a substantial portion of the nation's future energy needs. (LCL)

  2. Future groundwater extraction scenarios for an aquifer in a semiarid environment: case study of Guadalupe Valley Aquifer, Baja California, Northwest Mexico.

    PubMed

    Campos-Gaytan, Jose Ruben; Kretzschmar, Thomas; Herrera-Oliva, Claudia Soledad

    2014-11-01

    Semiarid northwestern Mexico presents a growing water demand produced by agricultural and domestic requirements during the last two decades. The community of Guadalupe Valley and the city of Ensenada rely on groundwater pumping from the local aquifer as its sole source of water supply. This dependency has resulted in an imbalance between groundwater pumpage and natural recharge. A two-dimensional groundwater flow model was applied to the Guadalupe Valley Aquifer, which was calibrated and validated for the period 1984-2005. The model analysis verified that groundwater levels in the region are subject to steep declines due to decades of intensive groundwater exploitation for agricultural and domestic purposes. The calibrated model was used to assess the effects of different water management scenarios for the period 2007-2025. If the base case (status quo) scenario continues, groundwater levels are in a continuous drawdown trend. Some wells would run dry by August 2017, and water demand may not be met without incurring in an overdraft. The optimistic scenario implies the achievement of the mean groundwater recharge and discharge. Groundwater level depletion could be stopped and restored. The sustainable scenario implies the reduction of current extraction (up to about 50 %), when groundwater level depletion could be stopped. A reduction in current extraction mitigates water stress in the aquifer but cannot solely reverse declining water tables across the region. The combination of reduced current extraction and an implemented alternative solution (such as groundwater artificial recharge), provides the most effective measure to stabilize and reverse declining groundwater levels while meeting water demands in the region.

  3. Q&A: The Basics of California's School Finance System

    ERIC Educational Resources Information Center

    EdSource, 2006

    2006-01-01

    In a state as large and complex as California, education financing can become as complicated as rocket science. This two-page Q&A provides a brief, easy-to-understand explanation of California's school finance system and introduces the issues of its adequacy and equity. A list of resources providing additional information is provided.

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

    USGS Publications Warehouse

    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

  5. Altitudes and thicknesses of hydrogeologic units of the Ozark Plateaus aquifer system in Arkansas, Kansas, Missouri, and Oklahoma

    USGS Publications Warehouse

    Westerman, Drew A.; Gillip, Jonathan A.; Richards, Joseph M.; Hays, Phillip D.; Clark, Brian R.

    2016-01-01

    A hydrogeologic framework of the Ozark Plateaus aquifer system was constructed as the base for a groundwater flow model developed as part of the U.S. Geological Survey Water Availability and Use Science Program to aid in the understanding of groundwater availability in select aquifer systems of the United States.  The Ozark Plateaus aquifer system study area (hereinafter referred to as the “Ozark system”) is nearly 70,000 square miles and includes parts of Arkansas, Kansas, Missouri, and Oklahoma.  A hydrogeologic framework was constructed to represent the altitudes and thicknesses of nine hydrogeologic units within the Ozark Plateaus aquifer system - . the Western Interior Plains confining system, Springfield Plateau aquifer, the Ozark confining unit, Ozark aquifer (divided into the upper, middle, and lower Ozark aquifers to better capture the spatial variation in the hydrologic properties), the St. Francois confining unit, the St. Francois aquifer, and the Basement confining unit. The formations that make up the hydrogeologic units of the Ozark system range from Pennsylvanian to Cambrian age. The scope of effort included the compilation and interpretation of hydrogeologic altitudes from geophysical, lithologic driller description, and well cutting logs. The final compiled dataset included more than 23,000 individual altitude points (excluding synthetic points) representing the nine hydrogeologic units. Shorthand names were used to identify points, extents, and raster surfaces corresponding to each hydrogeologic unit. WIPCS = Western Interior Plains confining system SPA = Springfield Plateau aquifer OCU = Ozark confining unit UOA = upper Ozark aquifer MOA = middle Ozark aquifer LOA = lower Ozark aquifer SFCU = St. Francois confining unit SFA = St. Francois aquifer BCU = Basement confining unit 

  6. Hydrogeology and water quality of the Floridan aquifer system and effect of Lower Floridan aquifer pumping on the Upper Floridan aquifer at Hunter Army Airfield, Chatham County, Georgia

    USGS Publications Warehouse

    Clarke, John S.; Williams, Lester J.; Cherry, Gregory C.

    2010-01-01

    Test drilling and field investigations, conducted at Hunter Army Airfield (HAAF), Chatham County, Georgia, during 2009, were used to determine the geologic, hydraulic, and water-quality characteristics of the Floridan aquifer system and to evaluate the effect of Lower Floridan aquifer (LFA) pumping on the Upper Floridan aquifer (UFA). Field investigation activities included (1) constructing a 1,168-foot (ft) test boring and well completed in the LFA, (2) collecting drill cuttings and borehole geophysical logs, (3) collecting core samples for analysis of vertical hydraulic conductivity and porosity, (4) conducting flowmeter and packer tests in the open borehole within the UFA and LFA, (5) collecting depth-integrated water samples to assess basic ionic chemistry of various water-bearing zones, and (6) conducting aquifer tests in the new LFA well and in an existing UFA well to determine hydraulic properties and assess interaquifer leakage. Using data collected at the site and in nearby areas, model simulation was used to quantify the effects of interaquifer leakage on the UFA and to determine the amount of pumping reduction required in the UFA to offset drawdown resulting from the leakage. Borehole-geophysical and flowmeter data indicate the LFA at HAAF consists of limestone and dolomitic limestone between depths of 703 and 1,080 ft, producing water from six major permeable zones: 723-731; 768-785; 818-837; 917-923; 1,027-1,052; and 1,060-1,080 ft. Data from a flowmeter survey, conducted at a pumping rate of 748 gallons per minute (gal/min), suggest that the two uppermost zones contributed 469 gal/min or 62.6 percent of the total flow during the test. The remaining four zones contributed from 1.7 to 18 percent of the total flow. Grab water samples indicate that with the exception of fluoride, constituent concentrations in the LFA increased with depth; water from the deepest interval (1,075 ft) contained chloride and sulfate concentrations of 480 and 240 milligrams per

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

    USGS Publications Warehouse

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

    1992-01-01

    The underlying Eau Claire Formation and its partial equivalent to the southwest, the Bonneterre Formation, form an important confining unit above the Mount Simon aquifer throughout much of the study area. Siltstone and shale are fairly common in the upper part of the Eau Claire Formation but less so in its northernmost extent in Wiscon

  8. Interdisciplinary modeling of the California Current System

    NASA Astrophysics Data System (ADS)

    Edwards, C. A.; Veneziani, M.; Broquet, G.; Goebel, N.; Moore, A. M.; Zehr, J. P.; Follows, M.

    2008-12-01

    The California Current System (CCS) refers to the collection of poleward and equatorward surface and subsurface currents that extends along the west coast of North America and a thousand kilometers offshore where it merges with the larger Pacific circulation. It exhibits strong seasonal fluctuations and rich mesoscale variability and supports a productive and diverse ecosystem with geographically varying communities. We report on the development and evaluation of an interdisciplinary modeling effort for this region. For the physical model, we use the Regional Ocean Modeling System, driven at the surface by output from the Coupled Ocean Atmosphere Mesoscale Prediction System and coupled at the lateral boundaries to GODAE- derived fields from the project, Estimating the Circulation and Climate of the Ocean. The forward physical model is evaluated using in situ hydrographic measurements and satellite-derived data. An incremental, strong-constraint, 4-dimensional variational approach assimilates this data, with evaluations based on model- data error statistics of both analysis and forecast fields. The ecosystem model, run in the forward model, supports 78 phytoplankton species and demonstrates self-organizing behavior. We focus this talk on the challenges associated with complex model evaluation in the coastal ocean. ~

  9. What explains the sulfur isotope fractionation observed in the aquifer system of Puebla Valley, Mexico?

    NASA Astrophysics Data System (ADS)

    Velazquez-Oliman, G.; Perry, E. C.; Leal-Bautista, R. M.; Lenczewski, M. E.

    2003-12-01

    Puebla Valley, Mexico is located in the central part of the Trans Mexican Volcanic Belt and is surrounded by 3 large volcanoes: Popocatepetl (active since 1994), Iztaccihuatl (extinct), and Malinche (dormant). The aquifer system of the Valley contains at least two productive units: an unconfined aquifer formed mainly of alluvial and volcanic deposits and a second, confined aquifer, which has chemically distinct water that is sulfur-rich, high in CO2, and high in alkalinity. There is a current debate about the origin of the sulfur-rich water, which is being used, after treatment, to lessen the deficit of water supply to the city of Puebla (with a population of approximately 1.5 million). Sulfate and sulfide species in water from the confined aquifer have an average sulfur isotope fractionation difference of 24.6 %. This fractionation is, at least in part, the result of bacterial sulfate reduction as evidenced by testing for bacteria with BART kits. Molecular analysis to identify the specific bacteria is underway. However, analysis of carbon isotopes of dissolved CO2 (with average delta 13C of 4.4%) and 3He/4He with average ratios of 2.1 for specific wells, located in the upper aquifer and characterized by having low sulfate but also rich in CO2 and alkalinity, suggest a possible magmatic component. The carbon and helium isotope analysis of water from the confined aquifer is currently underway.

  10. Hydrogeology and water quality of the Dublin and Midville aquifer systems at Waynesboro, Burke County, Georgia, 2011

    USGS Publications Warehouse

    Gonthier, Gerard J.

    2013-01-01

    The hydrogeology and water quality of the Dublin and Midville aquifer systems were characterized in the City of Waynesboro area in Burke County, Georgia, based on geophysical and drillers’ logs, flowmeter surveys, a 24-houraquifer test, and the collection and chemical analysis of water samples in a newly constructed well. At the test site, the Dublin aquifer system consists of interlayered sands and clays between depths of 396 and 691 feet, and the Midville aquifer system consists of a sandy clay layer overlying a sand and gravel layer between depths of 728 and 936 feet. The new well was constructed with three screened intervals in the Dublin aquifer system and four screened intervals in the Midville aquifer system. Wellbore-flowmeter testing at a pumping rate of 1,000 gallons per minute indicated that 52.2 percent of the total flow was from the shallower Dublin aquifer system with the remaining 47.8 percent from the deeper Midville aquifer system. The lower part of the lower Midville aquifer (900 to 930 feet deep), contributed only 0.1 percent of the total flow. Hydraulic properties of the two aquifer systems were estimated using data from two wellbore-flowmeter surveys and a 24-hour aquifer test. Estimated values of transmissivity for the Dublin and Midville aquifer systems were 2,000 and 1,000 feet squared per day, respectively. The upper and lower Dublin aquifers have a combined thickness of about 150 feet and the horizontal hydraulic conductivity of the Dublin aquifer system averages 10 feet per day. The upper Midville aquifer, lower Midville confining unit, and lower Midville aquifer have a combined thickness of about 210 feet, and the horizontal hydraulic conductivity of the Midville aquifer system averages 6 feet per day. Storage coefficient of the Dublin aquifer system, computed using the Theis method on water-level data from one observation well, was estimated to be 0.0003. With a thickness of about 150 feet, the specific storage of the Dublin aquifer

  11. Managed Aquifer Recharge Systems - Recognition of the Importance of Travel Time Surface Area Relationships (Invited)

    NASA Astrophysics Data System (ADS)

    Fox, P.

    2013-12-01

    In Managed Aquifer Recharge (MAR) systems, sub-surface transport provides an environmental buffer for the removal of many constituents. There are many potential variables that may impact the removal of pathogens, organic carbon, constituents of emerging concern, and nitrogen during sub-surface transport. However, the mechanisms for the removal of these constituents are primarily dependent on surface mediated reactions during sub-surface transport. Microbial reactions with microbes attached to surfaces are associated with the majority of transformations. Microbial transformations are sustainable and have been demonstrated to sustain the removal of organic carbon, various constituents of emerging concern and nitrogen in indirect potable reuse systems. Evaluating all removal mechanisms during sub-surface transport for different classes of contaminants is extremely difficult. When the variables of water quality, redox conditions, aquifer matrix and temperature are all considered, the experimental matrix necessary for evaluation becomes impractical. Many results published in the literature considered to be site specific which limits their practical utility. Nevertheless, strong similarities in the performance of MAR systems with respect to the removal of a broad range of contaminants exist for systems in the United States, Europe and Israel. One hypothesis for the robustness of these systems is that when travel time criteria are applied to their design, the surface area contact during sub-surface transport is similar in most MAR systems. Since removal mechanisms during sub-surface transport are dependent on surface area, systems with similar amounts of surface area can provide similar levels of removal. Makam and Fox (2009) considered the relationship between surface area and travel time in aquifers commonly associated with the environmental buffers of indirect potable reuse systems. For a specific hydraulic gradient and travel time, the surface area in aquifers

  12. Simulation of Groundwater Flow in the Coastal Plain Aquifer System of Virginia

    USGS Publications Warehouse

    Heywood, Charles E.; Pope, Jason P.

    2009-01-01

    The groundwater model documented in this report simulates the transient evolution of water levels in the aquifers and confining units of the Virginia Coastal Plain and adjacent portions of Maryland and North Carolina since 1890. Groundwater withdrawals have lowered water levels in Virginia Coastal Plain aquifers and have resulted in drawdown in the Potomac aquifer exceeding 200 feet in some areas. The discovery of the Chesapeake Bay impact crater and a revised conceptualization of the Potomac aquifer are two major changes to the hydrogeologic framework that have been incorporated into the groundwater model. The spatial scale of the model was selected on the basis of the primary function of the model of assessing the regional water-level responses of the confined aquifers beneath the Coastal Plain. The local horizontal groundwater flow through the surficial aquifer is not intended to be accurately simulated. Representation of recharge, evapotranspiration, and interaction with surface-water features, such as major rivers, lakes, the Chesapeake Bay, and the Atlantic Ocean, enable simulation of shallow flow-system details that influence locations of recharge to and discharge from the deeper confined flow system. The increased density of groundwater associated with the transition from fresh to salty groundwater near the Atlantic Ocean affects regional groundwater flow and was simulated with the Variable Density Flow Process of SEAWAT (a U.S. Geological Survey program for simulation of three-dimensional variable-density groundwater flow and transport). The groundwater density distribution was generated by a separate 108,000-year simulation of Pleistocene freshwater flushing around the Chesapeake Bay impact crater during transient sea-level changes. Specified-flux boundaries simulate increasing groundwater underflow out of the model domain into Maryland and minor underflow from the Piedmont Province into the model domain. Reported withdrawals accounted for approximately

  13. Conceptual hydrogeologic framework of the shallow aquifer system at Virginia Beach, Virginia

    USGS Publications Warehouse

    Smith, Barry S.; Harlow,, George E.

    2002-01-01

    The hydrogeologic framework of the shallow aquifer system at Virginia Beach was revised to provide a better understanding of the distribution of fresh ground water, its potential use, and its susceptibility to contamination. The revised conceptual framework is based primarily on analyses of continuous cores and downhole geophysical logs collected at 7 sites to depths of approximately 200 ft.The shallow aquifer system at Virginia Beach is composed of the Columbia aquifer, the Yorktown confining unit, and the Yorktown-East-over aquifer. The shallow aquifer system is separated from deeper units by the continuous St. Marys confining unit.The Columbia aquifer is defined as the predominantly sandy surficial deposits above the Yorktown confining unit. The Yorktown confining unit is composed of a series of very fine sandy to silty clay units of various colors at or near the top of the Yorktown Formation. The Yorktown confining unit varies in thickness and in composition, but on a regional scale is a leaky confining unit. The Yorktown-Eastover aquifer is defined as the predominantly sandy deposits of the Yorktown Formation and the upper part of the Eastover Formation above the confining clays of the St. Marys Formation. The limited areal extent of highly permeable deposits containing freshwater in the Yorktown-Eastover aquifer precludes the installation of highly productive freshwater wells over most of the city. Some deposits of biofragmental sand or shell hashes in the Yorktown-Eastover aquifer can support high-capacity wells.A water sample was collected from each of 10 wells installed at 5 of the 7 core sites to determine the basic chemistry of the aquifer system. One shallow well and one deep well was installed at each site. Concentrations of chloride were higher in the water from the deeper well at each site. Concentrations of dissolved iron in all of the water samples were higher than the U.S. Environmental Protection Agency Secondary Drinking Water Regulations

  14. The Southern Hills regional aquifer system of southeastern Louisiana and southwestern Mississippi

    USGS Publications Warehouse

    Buono, A.

    1983-01-01

    The Southern Hills regional aquifer system, named in a petition to the Environmental Protection Agency for designation as a sole or principal source of drinking water, is the primary source of public and domestic supplies in the northern 10 parishes of southeastern Louisiana. The gulfward dipping and thickening, complexly interbedded aquifer system extends from the northern limit of the recharge area near Vicksburg, Mississippi, as far as the Baton Rouge area in southeastern Louisiana. As many as 13 interdependent aquifer units compose the system in the southern part of the area and are known to coalesce or pinch out northward (updip) into fewer units. Aquifer water is almost exclusively a soft, sodium bicarbonate type with an average dissolved-solids concentration of about 220 milligrams per liter in southeastern Louisiana. Although several streams are available as alternatives for supply, they have not been accepted by local officials because of the additional water treatment that would be necessary and the extensive distribution system needed to deliver water to areas not near a source stream. Groundwater use in 1980 for public and domestic supply averaged 121 Mgal/d (million gallons per day), serving 744,000 people in southeastern Louisiana. In southwestern Mississippi, where the aquifer system is also the primary source for public and domestic supply, water use for these categories in 1980 totaled 25 Mgal/d, serving about 273,000 people. (USGS)

  15. The Maryland Coastal Plain Aquifer Information System: A GIS-based tool for assessing groundwater resources

    USGS Publications Warehouse

    Andreasen, David C.; Nardi, Mark R.; Staley, Andrew W.; Achmad, Grufron; Grace, John W.

    2016-01-01

    Groundwater is the source of drinking water for ∼1.4 million people in the Coastal Plain Province of Maryland (USA). In addition, groundwater is essential for commercial, industrial, and agricultural uses. Approximately 0.757 × 109 L d–1 (200 million gallons/d) were withdrawn in 2010. As a result of decades of withdrawals from the coastal plain confined aquifers, groundwater levels have declined by as much as 70 m (230 ft) from estimated prepumping levels. Other issues posing challenges to long-term groundwater sustainability include degraded water quality from both man-made and natural sources, reduced stream base flow, land subsidence, and changing recharge patterns (drought) caused by climate change. In Maryland, groundwater supply is managed primarily by the Maryland Department of the Environment, which seeks to balance reasonable use of the resource with long-term sustainability. The chief goal of groundwater management in Maryland is to ensure safe and adequate supplies for all current and future users through the implementation of appropriate usage, planning, and conservation policies. To assist in that effort, the geographic information system (GIS)–based Maryland Coastal Plain Aquifer Information System was developed as a tool to help water managers access and visualize groundwater data for use in the evaluation of groundwater allocation and use permits. The system, contained within an ESRI ArcMap desktop environment, includes both interpreted and basic data for 16 aquifers and 14 confining units. Data map layers include aquifer and ­confining unit layer surfaces, aquifer extents, borehole information, hydraulic properties, time-series groundwater-level data, well records, and geophysical and lithologic logs. The aquifer and confining unit layer surfaces were generated specifically for the GIS system. The system also contains select groundwater-quality data and map layers that quantify groundwater and surface-water withdrawals. The aquifer

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

    EPA Science Inventory

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

  17. Pumping-induced drawdown and stream depletion in a leaky aquifer system

    USGS Publications Warehouse

    Butler, J.J.; Zhan, X.; Zlotnik, V.A.

    2007-01-01

    The impact of ground water pumping on nearby streams is often estimated using analytic models of the interconnected stream-aquifer system. A common assumption of these models is that the pumped aquifer is underlain by an impermeable formation. A new semianalytic solution for drawdown and stream depletion has been developed that does not require this assumption. This solution shows that pumping-induced flow (leakage) through an underlying aquitard can be an important recharge mechanism in many stream-aquifer systems. The relative importance of this source of recharge increases with the distance between the pumping well and the stream. The distance at which leakage becomes the primary component of the pumping-induced recharge depends on the specific properties of the aquifer, aquitard, and streambed. Even when the aquitard is orders of magnitude less transmissive than the aquifer, leakage can be an important recharge mechanism because of the large surface area over which it occurs. Failure to consider aquitard leakage can lead to large overestimations of both the drawdown produced by pumping and the contribution of stream depletion to the pumping-induced recharge. The ramifications for water resources management and water rights adjudication can be significant. A hypothetical example helps illustrate these points and demonstrates that more attention should be given to estimating the properties of aquitards underlying stream-aquifer systems. The solution presented here should serve as a relatively simple but versatile tool for practical assessments of pumping-induced stream-aquifer interactions. However, this solution should not be used for such assessments without site-specific data that indicate pumping has induced leakage through the aquitard. ?? 2006 National Ground Water Association.

  18. Capture zone of a multi-well system in bounded peninsula-shaped aquifers.

    PubMed

    Zarei-Doudeji, Somayeh; Samani, Nozar

    2014-08-01

    In this paper we present the equation of capture zone for multi-well system in peninsula-shaped confined and unconfined aquifers. The aquifer is rectangular in plan view, bounded along three sides, and extends to infinity at the fourth side. The bounding boundaries are either no-flow (impervious) or in-flow (constant head) so that aquifers with six possible boundary configurations are formed. The well system is consisted of any number of extraction or injection wells or combination of both with any flow rates. The complex velocity potential equations for such a well-aquifer system are derived to delineate the capture envelop. Solutions are provided for the aquifers with and without a uniform regional flow of any directions. The presented equations are of general character and have no limitations in terms of well numbers, positions and types, extraction/injection rate, and regional flow rate and direction. These solutions are presented in form of capture type curves which are useful tools in hands of practitioners to design in-situ groundwater remediation systems, to contain contaminant plumes, to evaluate the surface-subsurface water interaction and to verify numerical models.

  19. Revised hydrogeologic framework of the Floridan aquifer system in Florida and parts of Georgia, Alabama, and South Carolina

    USGS Publications Warehouse

    Williams, Lester J.; Kuniansky, Eve L.

    2015-04-08

    The hydrogeologic framework for the Floridan aquifer system has been revised throughout its extent in Florida and parts of Georgia, Alabama, and South Carolina. The updated framework generally conforms to the original framework established by the U.S. Geological Survey in the 1980s, except for adjustments made to the internal boundaries of the Upper and Lower Floridan aquifers and the individual higher and contrasting lower permeability zones within these aquifers. The system behaves as one aquifer over much of its extent; although subdivided vertically into two aquifer units, the Upper and Lower Floridan aquifers. In the previous framework, discontinuous numbered middle confining units (MCUI–VII) were used to subdivide the system. In areas where less-permeable rocks do not occur within the middle part of the system, the system was previously considered one aquifer and named the Upper Floridan aquifer. In intervening years, more detailed data have been collected in local areas, resulting in some of the same lithostratigraphic units in the Floridan aquifer system being assigned to the Upper or Lower Floridan aquifer in different parts of the State of Florida. Additionally, some of the numbered middle confining units are found to have hydraulic properties within the same order of magnitude as the aquifers. A new term “composite unit” is introduced for lithostratigraphic units that cannot be defined as either a confining or aquifer unit over their entire extent. This naming convention is a departure from the previous framework, in that stratigraphy is used to consistently subdivide the aquifer system into upper and lower aquifers across the State of Florida. This lithostratigraphic mapping approach does not change the concept of flow within the system. The revised boundaries of the Floridan aquifer system were mapped by considering results from local studies and regional correlations of lithostratigraphic and hydrogeologic units or zones. Additional zones within

  20. Simulations of flow in the Edwards-Trinity aquifer system and contiguous hydraulically connected units, west-central Texas

    USGS Publications Warehouse

    Kuniansky, E.L.; Holligan, K.Q.

    1994-01-01

    The transmissivity values used in the simulations were within estimated ranges and generally are: 1,000 to 10,000 ft2/d (feet squared per day) for the Edwards-Trinity and Trinity aquifers; 100,000 to greater than 1 million ft2/d for the Edwards aquifer; and less than 500 to 10,000 ft2/d in contiguous hydraulically connected units. Simulated flow through the Edwards-Trinity aquifer system and contiguous hydraulically connected units is about 3 million acre-feet per year. Estimates of areally distributed recharge from the simulations range from 0.1 to 1 inch per year for the Edwards-Trinity aquifer and increase to 4 inches per year for the Trinity aquifer. Recharge to the Edwards aquifer occurs along streambeds that cross outcropped high-permeability rocks of the Edwards Group through joints and faults. Many of the streams are diverted completely underground during periods of no precipitation. The movement of a substantial quantity of water (about 400 cubic feet per second) from the Trinity and Edwards-Trinity aquifers into the Edwards aquifer was simulated. Results of the simulations indicate that anisotropy strongly influences flow in the Edwards aquifer. In the San Antonio and Austin areas, the Edwards aquifer is the most active part of the ground-water flow system with one-third of ground-water discharge occurring in 5 percent of the modeled area for both simulations.

  1. Building Better Buildings: Sustainable Building Activities in California Higher Education Systems.

    ERIC Educational Resources Information Center

    Sowell, Arnold; Eichel, Amanda; Alevantis, Leon; Lovegreen, Maureen

    2003-01-01

    This article outlines the activities and recommendations of California's sustainable building task force, discusses sustainable building activities in California's higher education systems, and highlights key issues that California is grappling with in its implementation of sustainable building practices. (EV)

  2. Plan of study for the Ohio-Indiana carbonate-bedrock and glacial- aquifer system

    USGS Publications Warehouse

    Bugliosi, E.F.

    1990-01-01

    The major aquifers of 35,000 sq mi area in western Ohio and eastern Indiana consist of Silurian and Devonian carbonate bedrock and Quaternary glacial deposits. These bedrock units and glacial deposits have been designated for study as part of the U.S. Geological Survey 's Regional Aquifer System Analysis program, a nationwide program to assess the regional hydrology, geology and water quality of the Nation 's most important aquifers. The purpose of the study is to define the hydrology, geochemistry, and geologic framework of the aquifer system within the Silurian and Devonian rocks and glacial deposits, with emphasis on describing the groundwater flow patterns and characterizing the water quality. The study, which began in 1988 , is expected to be completed in 1993. In 1980, the aquifers in the study area supplied more than 280 million gallons of water/day to industry, agriculture, and a population of more than 6.3 million people. With a projected future population growth to 7.1 million in 1990, and with intensified agricultural and industrial uses, water withdrawals from these bedrock and glacial aquifers are expected to be increased. The most significant groundwater problems in the study area result from the pronounced areal differences in availability and quality of the groundwater. These differences are related to the lateral discontinuity of many of the glacial deposits and to variations in secondary permeability of the bedrock aquifers associated with patterns of fracturing. Planned activities of the study include compilation of available geohydrologic and water quality data, such as groundwater levels, geohydrologic properties of aquifers, chemical analyses, land use and water use data, and ancillary data such as digital satellite images. Additional geohydrologic and water quality data may be collected from existing wells or wells that may be drilled for this study. A computerized, geographic information system will be used as a data base management tool and

  3. Ground-water flow and quality in Wisconsin's shallow aquifer system

    USGS Publications Warehouse

    Kammerer, P.A.

    1995-01-01

    In terms of chemical quality, the water is suitable for potable supply and most other uses, but objectionable hardness in large areas and concen- trations of iron and manganese that exceed State drinking-water standards cause aesthetic problems that may require treatment of the water for some uses. Concentrations of major dissolved constitu- ents (calcium, magnesium, and bicarbonate), hard- ness, alkalinity, and dissolved solids are highest where the bedrock component of the aquifer is dolo- mite and lowest where the shallow aquifer is almost entirely sand and gravel. Concentrations of other minor constituents (sodium, potassium, sulfate, chloride, and fluoride) are less closely related to common minerals that compose the aquifer system. Sulfate and fluoride concentrations exceed State drinking-water standards locally. Extreme variability in concentrations of iron and manganese are common locally. Iron and manganese concentra- tions exceed State drinking-water standards in water from one-third and one-quarter of the wells, respectively. Likely causes of nitrate-nitrogen con- centrations that exceed State drinking-water stan- dards include local contamination from plant fertilizers, animal wastes, waste water disposed of on land, and septic systems. Water quality in the shallow aquifer system has been affected by saline water from underlying aquifers, primarily along the eastern and western boundaries of the State where the thickness of Paleozoic rocks is greatest.

  4. Geochemistry of the Cambrian-Ordovician aquifer system in the northern Midwest, United States

    SciTech Connect

    Siegel, D.I.

    1989-01-01

    Distributions of solutes in aquifers of Cambrian and Ordovician age were studied in Minnesota, Wisconsin, Iowa, Illinois, northwestern Indiana, and northern Missouri to determine the sources of solutes and the probable chemical mechanisms that control regional variations in water quality. The data base used included more than 3,000 ground-water-quality analyses from all major aquifers, but especially from the St. Peter, Jordan, and Mount Simon Sandstones and their equivalents. Regional variations in the water chemistry of glacial drift and other sedimentary units that overlie the Cambrian-Ordovician aquifer system in recharge areas in Minnesota, Iowa, Wisconsin, and Illinois were also studied, but to a lesser degree. The most important chemical variation in the aquifer is the change in water type from calcium-sodium-sulfate-bicarbonate water to sodium-calcium-sulfate-bicarbonate and sodium-chloride waters along the longest regional flow path from northwestern Iowa to the Illinois basin. The most striking aspect of the distribution of dissolved solids and carbon isotopic content of bicarbonate is the increase in concentration and isotopic enrichment from southwestern Wisconsin, southern Minnesota, and northwestern Illinois south toward Missouri. This study indicates that the ground water in the region is thousands of years old. The study also indicates that the major chemical trends in the aquifers probably are related as much to paleohydrogeologic flow systems during Pleistocene time as to the present flow system, which may postdate the retreat of the last ice sheet about 12,000 years ago.

  5. Field testing of a high-temperature aquifer thermal energy storage system

    SciTech Connect

    Sterling, R.L.; Hoyer, M.C.

    1989-03-01

    The University of Minnesota Aquifer Thermal Energy Storage (ATES) System has been operated as a field test facility for the past six years. Four short-term and two long-term cycles have been completed to data providing a greatly increased understanding of the efficiency and geochemical effects of high-temperature aquifer thermal energy storage. A third long-term cycle is currently being planned to operate the ATES system in conjunction with a real heating load and to further study the geochemical impact on the aquifer from heated waste storage cycles. The most critical activities in the preparation for the next cycle have proved to be the applications for the various permits and variances necessary to conduct the third cycle and the matching of the characteristics of the ATES system during heat recovery with a suitable adjacent building thermal load.

  6. Detailed performance and environmental monitoring of aquifer heating and cooling systems

    NASA Astrophysics Data System (ADS)

    Acuna, José; Ahlkrona, Malva; Zandin, Hanna; Singh, Ashutosh

    2016-04-01

    The project intends to quantify the performance and environmental impact of large scale aquifer thermal energy storage, as well as point at recommendations for operating and estimating the environmental footprint of future systems. Field measurements, test of innovative equipment as well as advanced modelling work and analysis will be performed. The following aspects are introduced and covered in the presentation: -Thermal, chemical and microbiological influence of akvifer thermal energy storage systems: measurement and evaluation of real conditions and the influence of one system in operation. -Follow up of energy extraction from aquifer as compared to projected values, recommendations for improvements. -Evaluation of the most used thermal modeling tool for design and calculation of groundwater temperatures, calculations with MODFLOW/MT3DMS -Test and evaluation of optical fiber cables as a way to measure temperatures in aquifer thermal energy storages

  7. Hydrogeology of the Helena Valley-fill aquifer system, west-central Montana. Water resources investigation

    SciTech Connect

    Briar, D.W.; Madison, J.P.

    1992-01-01

    The report, which presents the study results, describes the hydrogeology of the valley-fill aquifer system. Specific objectives were to: describe the geometry and the hydraulic characteristics of the aquifer system; define the potentiometric surface and the direction of ground-water flow; locate and quantify sources of ground-water recharge and discharge including surface- and ground-water interactions; and characterize the water quality in terms of susceptibility of the aquifer system to contamination and in terms of concentrations, distribution, and sources of major ions, trace elements, and organic compounds. The results of the study will be useful to the development of a comprehensive management program for the use and protection of the ground-water resources of the Helena Valley.

  8. Aqueous geochemistry and diagenesis in the eastern Snake River Plain aquifer system, Idaho

    USGS Publications Warehouse

    Wood, Warren W.; Low, Walton H.

    1986-01-01

    Water budget and isotopic analyses of water in the eastern Snake River Plain aquifer system confirm that most, if not all, of the water is local meteoric in origin. Solute mass-balance arguments suggest that ∼5 × 109 moles of calcite and 2.6 × 109 moles of silica are precipitated annually in the aquifer. Isotopic evaluations of calcite and petrographic observation of silica support the low-temperature origin of these deposits. Approximately 2.8 × 109 moles of chloride, 4.5 × 109 moles of sodium, 1.4 × 109 moles of sulfate, and 2 × 109 moles of magnesium are removed annually from the aquifer framework by solution. Proposed weathering reactions are shown to be consistent with mass balance, carbon isotopes, observed mineralogy, and chemical thermodynamics. Large quantities of sodium, chloride, and sulfate are being removed from the system relative to their abundances in the rock. Sedimentary interbeds, which are estimated to compose <10% of the aquifer volume, may yield as much as 20% of the solutes generated within the aquifer. Weathering rate of the aquifer framework of the eastern Snake River Plain is 14 (Mg/km2)/yr or less than half the average of the North American continent. This contrasts with the rate for the eastern Snake River basin, 34 (Mg/km2)/yr, which is almost identical to the average for the North American continent. Identification and quantification of reactions controlling solute concentrations in ground water in the eastern plain indicate that the aquifer is not an “inert bathtub” that simply stores and transmits water and solutes but is undergoing active diagenesis and is both a source and sink for solutes.

  9. Two well storage systems for combined heating and airconditioning by groundwater heatpumps in shallow aquifers

    SciTech Connect

    Pelka, W.

    1980-07-01

    The use of soil and ground water as an energy source and heat storage systems for heat pumps in order to conserve energy in heating and air conditioning buildings is discussed. Information is included on heat pump operation and performance, aquifer characteristics, soil and ground water temperatures, and cooling and heating demands. Mathematical models are used to calculate flow and temperature fields in the aquifer. It is concluded that two well storage systems with ground water heat pumps are desirable, particularly in northern climates. (LCL)

  10. Two well storage systems for combined heating and airconditioning by groundwater heatpumps in shallow aquifers

    NASA Astrophysics Data System (ADS)

    Pelka, W.

    1980-07-01

    The use of soil and ground water as an energy source and heat storage systems for heat pumps in order to conserve energy in heating and air conditioning buildings is discussed. Information is included on heat pump operation and performance, aquifer characteristics, soil and ground water temperatures, and cooling and heating demands. Mathematical models are used to calculate flow and temperature fields in the aquifer. It is concluded that two well storage systems with ground water heat pumps are desirable, particularly in northern climates.

  11. Groundwater artificial recharge solutions for integrated management of watersheds and aquifer systems under extreme drought scenarios

    NASA Astrophysics Data System (ADS)

    Lobo-Ferreira, Joao-Paulo; Oliveira, Luís.; Diamantino, Catarina

    2010-05-01

    The paper addresses groundwater artificial recharge solutions for integrated management of watersheds and aquifer systems under extreme drought scenarios. The conceptual idea of Aquifer Storage and Recovery (ASR) is considered as one of the scientific based solutions towards scientific based mitigation measures to climate variability and change in many parts of the world. In Portugal two European Union sponsored 6th Framework Programme for Research Projects have been addressing this topic, namely GABARDINE Project on "Groundwater artificial recharge based on alternative sources of water: Advanced integrated technologies and management" and the Coordinated Action ASEMWATERNet, a "Multi-Stakeholder Platform for ASEM S&T Cooperation on Sustainable Water Use". An application of Aquifer Storage and Recovery methodologies aiming drought mitigation and Integrated Water Resource Management of the Algarve (Portugal). The technique of artificial recharge of groundwater is used in many parts of the world with several aims, e.g. water storing in appropriate aquifers for the mitigation of future water needs during droughts or as protection against pollution or even for the recovery of groundwater quality. Artificial recharge of the aquifer systems of Campina de Faro and Silves-Querença is addressed in this paper, proposed to be an alternative to decrease the vulnerability of the Algarve to a future drought. Integrated management of water resources in the Algarve is not a clear issue since the last decade, when groundwater resources that supplied almost all water needs, have been drastically replaced by surface water stored in new reservoirs.

  12. The water footprint of California's energy system, 1990-2012.

    PubMed

    Fulton, Julian; Cooley, Heather

    2015-03-17

    California's energy and water systems are interconnected and have evolved in recent decades in response to changing conditions and policy goals. For this analysis, we use a water footprint methodology to examine water requirements of energy products consumed in California between 1990 and 2012. We combine energy production, trade, and consumption data with estimates of the blue and green water footprints of energy products. We find that while California's total annual energy consumption increased by just 2.6% during the analysis period, the amount of water required to produce that energy grew by 260%. Nearly all of the increase in California's energy-related water footprint was associated with water use in locations outside of California, where energy products that the state consumes were, and continue to be, produced. We discuss these trends and the implications for California's future energy system as it relates to climate change and expected water management challenges inside and outside the state. Our analysis shows that while California's energy policies have supported climate mitigation efforts, they have increased vulnerability to climate impacts, especially greater hydrologic uncertainty. More integrated analysis and planning are needed to ensure that climate adaptation and mitigation strategies do not work at cross purposes.

  13. Large sedimentary aquifer systems functioning. Constraints by classical isotopic and chemical tools, and REE in the Eocene sand aquifer, SW France

    NASA Astrophysics Data System (ADS)

    Petelet-Giraud, E.; Negrel, P. J.; Millot, R.; Guerrot, C.; Brenot, A.; Malcuit, E.

    2010-12-01

    Large sedimentary aquifer systems often constitute strategic water resources for drinking water supply, agriculture irrigation and industry, but can also represent an energetic resource for geothermal power. Large water abstractions can induce complete modification of the natural functioning of such aquifer systems, e.g. with seepage between aquifer layers that can lead to water quality degradation. These large aquifer systems thus require rational water management at the sedimentary basin scale in order to preserve both water quantity and quality. In addition to hydrogeological modelling mainly dealing with water quantity, chemical and isotopic methods were applied to evidence the spatial variability of water characteristics and to turn this into better understanding of hydrosystems functioning. The large Eocene Sand aquifer system of the Adour-Garonne sedimentary basin was studied through various hydrological, chemical and isotopic tools. This system extends over 116,000 km2 (one-fifth of the French territory, located in the South west part). The aquifer being artesian in the west of the district and confined with piezometric levels around 250-m depth in the east. The ‘Eocene Sands’, composed of sandy Tertiary sediments alternating with carbonate deposits, is a multi-layer system with high permeability and a thickness of several tens of metres to a hundred metres..The Eocene Sand aquifer system comprises at least five aquifers: Paleocene, Eocene infra-molassic sands (IMS), early Eocene, middle Eocene, and late Eocene. According to δ18O and δ2H values and estimated 14C ages, both present-day recharge (mainly located in the north of the area) and old recharge (16-35 ky) can be evidenced. High spatial variability was evidenced within a same aquifer layer, with temporal variability over one hydrological cycle limited to a few points located in the recharge areas. These results and especially the very old waters recharged under colder climate combined with the

  14. Two-dimensional ground-water flow model of the Cretaceous aquifer system of Lee County and vicinity, Mississippi

    USGS Publications Warehouse

    Kernodle, John Michael

    1981-01-01

    A two-dimensional ground-water flow model of the Eutaw-McShan and Gordo aquifers in the area of Lee County, Miss., was successfully calibrated and verified using data from six long-term observation wells and two intensive studies of areal water levels. The water levels computed by the model were found to be most sensitive to changes in simulated aquifer hydraulic conductivity and to changes in head in the overlying Coffee Sand aquifer. The two-dimensional model performed reasonably well in simulating the aquifer system except possibly in southern Lee County and southward where a clay bed at the top of the Gordo Formation partially isolated the Gordo from the overlying Eutaw-McShan aquifer. The verified model was used to determine theoretical aquifer response to increased ground-water withdrawal to the year 2000. Two estimated rates of increase and five possible well field locations were examined. (USGS)

  15. The groundwater age in the Middle-Upper Devonian aquifer system, Lithuania

    NASA Astrophysics Data System (ADS)

    Mokrik, R.; Mažeika, J.; Baublytė, A.; Martma, T.

    2009-06-01

    3H, δ13C and hydrochemical data were used to estimate the corrected groundwater age derived from conventional 14C age of dissolved inorganic carbon (DIC). The Middle-Upper Devonian aquifer system from the Baltic upland recharge area in eastern Lithuania towards the discharge area on the Baltic Sea coast in the west was considered. The concentration of total dissolved solids (TDS) in groundwater changes from 300 to 24,000 mg/L and increases downgradient towards the coast. The other major constituents have the same trend as the TDS. The hydrochemical facies of groundwater vary from an alkali-earth carbonates facies at the eastern upland area to an alkali-earth carbonate-sulfate and chloride facies at transit and discharge areas. Meteoric water percolating through the Quaternary and Devonian aquifers regulate the initial 14C activities of groundwater involving two main members of DIC: soil CO2 with modern 14C activity uptake and dissolution of 14C-free aquifer carbonates. Other sources of DIC are less common. 14C activity of DIC in the groundwater ranged from 60 to 108 pMC at the shallow depths. With an increase of the aquifers depth the dolomitization of aqueous solution and leakage of the “old” groundwater from lower aquifers take place, traced by lower activities (7-30 pMC).

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

    USGS Publications Warehouse

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

    2014-01-01

    Regionally, water in the lower Tertiary and Upper Cretaceous aquifer systems flows in a northerly or northeasterly direction from the Powder River structural basin to the Williston structural basin. Groundwater flow in the Williston structural basin generally is easterly or northeasterly. Flow in the uppermost hydrogeologic units generally is more local and controlled by topography where unglaciated in the Williston structural basin than is flow in the glaciated part and in underlying aquifers. Groundwater flow in the Powder River structural basin generally is northerly with local variations greatest in the uppermost aquifers. Groundwater is confined, and flow is regional in the underlying aquifers.

  17. Assessing the Vulnerability of Public-Supply Wells to Contamination: Floridan Aquifer System Near Tampa, Florida

    USGS Publications Warehouse

    Jagucki, Martha L.; Katz, Brian G.; Crandall, Christy A.; Eberts, Sandra M.

    2009-01-01

    This fact sheet highlights findings from the vulnerability study of a public-supply well in Temple Terrace, Florida, northeast of Tampa. The well selected for study typically produces water at the rate of 700 gallons per minute from the Upper Floridan aquifer. Water samples were collected at the public-supply well and at monitoring wells installed in or near the simulated zone of contribution to the supply well. Samples of untreated water from the public-supply wellhead contained the undesirable constituents nitrate, arsenic, uranium, radon-222, volatile organic compounds (VOCs), and pesticides, although all were detected at concentrations less than established drinking-water standards, where such standards exist. Overall, study findings point to four primary factors that affect the movement and fate of contaminants and the vulnerability of the public-supply well in Temple Terrace: (1) groundwater age (how long ago water entered, or recharged, the aquifer); (2) short-circuiting of contaminated water through sinkholes; (3) natural geochemical processes within the aquifer; and (4) pumping stress. Although the public-supply well is completed in the Upper Floridan aquifer, it produces water with concentrations of nitrate, VOCs, and the natural contaminant radon that are intermediate between the typical composition of water from the Upper Floridan aquifer and that of the overlying surficial aquifer system. Mixing calculations show that the water produced by the public-supply well could consist of upwards of 50 percent water from the surficial aquifer system mixed with water from the Upper Floridan aquifer. Anthropogenically affected water from the surficial aquifer system travels rapidly to depth through sinkholes that must be directly connected to the cavernous zone intersected by the public-supply well (and several other production wells in the region). Such solution features serve as fast pathways to the well and circumvent the natural attenuation of nitrate and

  18. Ground-water flow in the shallow aquifer system at the Naval Weapons Station Yorktown, Virginia

    USGS Publications Warehouse

    Smith, Barry S.

    2001-01-01

    The Environmental Directorate of the Naval Weapons Station Yorktown, Virginia, is concerned about possible contamination of ground water at the Station. Ground water at the Station flows through a shallow system of layered aquifers and leaky confining units. The units of the shallow aquifer system are the Columbia aquifer, the Cornwallis Cave confining unit, the Cornwallis Cave aquifer, the Yorktown confining unit, and the Yorktown-Eastover aquifer. The Eastover-Calvert confining unit separates the shallow aquifer system from deeper confined aquifers beneath the Station. A three-dimensional, finite-difference, ground-water flow model was used to simulate steady-state ground-water flow of the shallow aquifer system in and around the Station. The model simulated ground-water flow from the peninsular drainage divide that runs across the Lackey Plain near the southern end of the Station north to King Creek and the York River and south to Skiffes Creek and the James River. The model was calibrated by minimizing the root mean square error between 4 7 measured and corresponding simulated water levels. The calibrated model was used to determine the ground-water budget and general directions of ground-water flow. A particle-tracking routine was used with the calibrated model to estimate groundwater flow paths, flow rates, and traveltimes from selected sites at the Station. Simulated ground-water flow velocities of the Station-area model were small beneath the interstream areas of the Lackey Plain and Croaker Flat, but increased outward toward the streams and rivers where the hydraulic gradients are larger. If contaminants from the land surface entered the water table at or near the interstream areas of the Station, where hydraulic gradients are smaller, they would migrate more slowly than if they entered closer to the streams or the shores of the rivers where gradients commonly are larger. The ground-water flow simulations indicate that some ground water leaks downward from

  19. Geochemistry of the Cambrian-Ordovician aquifer system in the northern Midwest, United States: D in Regional aquifer-system analysis

    USGS Publications Warehouse

    Siegel, D.I.

    1989-01-01

    Distributions of dissolved trace constituents in the aquifers probably are related to the proximity to mineralogic sources as well as chemical and hydraulic mechanisms. For example, concentrations of some constituents, such as cadmium and arsenic, are largest in the vicinity of the Dakota Formation in northwestern Iowa. Other constituents, such as beryllium and vanadium, have larger concentrations near the edge of the Forest City basin in southwestern Iowa and northwestern Missouri. Strontium and fluoride concentrations generally increase from north to south, which suggests the input of these trace constituents during the recharge events. However, concentrations of bromide, radium-226, and lithium show distribution patterns similar to the "plume" defined by dissolved solids and isotopes of water, suggesting dilution of concentrations of trace constituents by Pleistocene recharge. Concentrations of other constituents are partly controlled by aquifer temperature, such as silica in south-central Iowa, and solubility controls, such as barium in northeastern Illinois. Additional information on the chemical and mineralogical composition of the aquifer matrix and the isotopically lightest ground water is needed to evaluate the hypothesis of Pleistocene mixing before more quantitative studies can be done to evaluate the different proposed mechanisms that have controlled and modified the water chemistry over time. This study, however, indicates that the ground water in the region is thousands of years old. The study also indicates that the major chemical trends in the aquifers probably are related as much to paleohydrogeologic flow systems during Pleistocene time as to the present flow system, which may postdate the retreat of the last ice sheet about 12,000 years ago.

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

    USGS Publications Warehouse

    Marella, Richard L.; Berndt, Marian P.

    2005-01-01

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

  1. Groundwater quality in the Northern Atlantic Coastal Plain aquifer system, eastern United States

    USGS Publications Warehouse

    Lindsey, Bruce; Belitz, Kenneth

    2017-01-19

    Groundwater provides nearly 50 percent of the Nation’s drinking water. To help protect this vital resource, the U.S. Geological Survey (USGS) National Water-Quality Assessment (NAWQA) Project assesses groundwater quality in aquifers that are important sources of drinking water. The Northern Atlantic Coastal Plain aquifer system constitutes one of the important areas being evaluated. One or more inorganic constituents with human-health benchmarks were detected at high concentrations in about 15 percent of the study area and at moderate concentrations in about 17 percent. Organic constituents were not detected at high concentrations in the study area.

  2. Evaluation of Flow Dynamics in a Karst Aquifer System at Sapanca Lake Basin (turkey) via Hydrochemical and Isotopic Data

    NASA Astrophysics Data System (ADS)

    Gunduz, O. C.; Yolcubal, I.

    2013-12-01

    Sapanca Lake, located 20 km west of Izmit bay, is a fresh water lake with tectonic origin and supplies drinking and municipal water to the region. Groundwater discharges from a karstic aquifer developed in Permo-Triassic and Late Jurassic-Early Cretaceous aged marbles and an alluvial aquifer distributed in east-west direction on the Sapanca plain play an important role in the recharge of the lake. In the Sapanca lake basin, there are numerous springs discharging (1 to 75 lt/s) from different elevations of the karstic aquifer system. Dolines, sinkholes, depression fields, and disappearing rivers developed on the southern heights of the basin are directly connected with the karstic aquifer and allow the aquifer system to show rapid recharge and discharge characteristics. In the scope of the study, 25 karst spring waters as well as 25 wells drilled in the alluvial aquifer were sampled as representatives of dry and rainy periods. Hydrochemical and isotopic (18O/2D/3H) compositions of the samples were evaluated along with the hydrogeology and the fracture analysis of the basin in order to assess the hydraulic relationship between the aquifer systems and the groundwater circulation in the basin. Results show that groundwaters from alluvial and karstic aquifers are modern water and demonstrate similar hydrochemical facies (Ca-HCO3 ve Ca+Mg-HCO3). Although showing seasonal differences, isotopic composition (18O/2D) of the karst springs resembles those of the streams and groundwaters from alluvial aquifer. This suggests that ground and surface waters feed each other periodically and characterize a mixing. Fracture analysis of the basin suggests that faulting has significant control over groundwater discharge and circulation in the karst aquifer and form discontinuities in the system, subdividing it into several aquifer sub-systems.

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

    USGS Publications Warehouse

    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 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

  4. Long-term geochemical evaluation of the coastal Chicot aquifer system, Louisiana, USA

    NASA Astrophysics Data System (ADS)

    Borrok, David M.; Broussard, Whitney P.

    2016-02-01

    Groundwater is increasingly being overdrafted in the Gulf and Atlantic Coastal regions of the United States. Geochemical data associated with groundwater in these aquifers can provide important information on changes in salinity, recharge, and reaction pathways that can be used to improve water management strategies. Here we evaluated long-term geochemical changes associated with the 23,000 km2 Chicot aquifer system in Louisiana, USA. The Chicot aquifer is currently being overdrafted by about 1,320,000 m3 per day. We compiled selected bulk geochemical data from samples collected from 20 wells in the Chicot aquifer from 1993 to 2015. Oxygen and hydrogen isotope measurements were additionally completed for the 2014 samples. We identified three zones of groundwater with distinctive geochemical character; (1) A groundwater recharge zone in the northern part of the study area with low pH, low salinity, and low temperature relative to other groundwater samples, (2) a groundwater recharge zone in the southeastern part of the study area with low temperature, high alkalinity, and higher Ca and Mg concentrations compared to the other groundwater samples, and (3) groundwater in the southwestern part of the aquifer system with high salinity, high temperature, and a ∼1:1 Na/Cl ratio. The geochemistry of these regions has been relatively stable over the last ∼20 years. However, in the drought year of 2011, the estimated extent of zones with elevated salinity increased substantially. Geochemical evidence suggests that there was increased infiltration of deeper, more salt-rich waters into the shallower Chicot aquifer.

  5. Seawater intrusion and potential yield of aquifers in the Soquel-Aptos area, Santa Cruz County, California

    USGS Publications Warehouse

    Muir, K.S.

    1980-01-01

    Seawater has intruded the Purisima Formation in the interval 0-100 feet below sea level in the Soquel-Aptos area. It occurs in the central part of the area and extends inland about half a mile. The potential yields of the two principal aquifers in the Soquel-Aptos area are 4,400 acre-feet per year from the Purisima Formation and 1,500 acre-feet per year from the Aromas Sand. Pumping from the Purisima Formation, averaging about 5,400 acre-feet per year since 1970, has caused water levels along the coast to decline below sea level and has allowed seawater to enter the aquifer. Seawater intrusion and ground-water storage could be monitored in all depth zones by expanding the observation-well network to include a number of shallow wells, one deep well inland from the coast, and three deep wells along the coast. (USGS)

  6. Altitudes and thicknesses of hydrogeologic units of the Ozark Plateaus aquifer system in Arkansas, Kansas, Missouri, and Oklahoma

    USGS Publications Warehouse

    Westerman, Drew A.; Gillip, Jonathan A.; Richards, Joseph M.; Hays, Phillip D.; Clark, Brian R.

    2016-09-29

    A hydrogeologic framework was constructed to represent the altitudes and thicknesses of hydrogeologic units within the Ozark Plateaus aquifer system as part of a regional groundwater-flow model supported by the U.S. Geological Survey Water Availability and Use Science Program. The Ozark Plateaus aquifer system study area is nearly 70,000 square miles and includes parts of Arkansas, Kansas, Missouri, and Oklahoma. Nine hydrogeologic units were selected for delineation within the aquifer system and include the Western Interior Plains confining system, the Springfield Plateau aquifer, the Ozark confining unit, the Ozark aquifer, which was divided into the upper, middle, and lower Ozark aquifers to better capture the spatial variation in the hydrologic properties, the St. Francois confining unit, the St. Francois aquifer, and the basement confining unit. Geophysical and well-cutting logs, along with lithologic descriptions by well drillers, were compiled and interpreted to create hydrologic altitudes for each unit. The final compiled dataset included more than 23,000 individual altitude points (excluding synthetic points) representing the nine hydrogeologic units within the Ozark Plateaus aquifer system.

  7. Hydrogeology and potential for ground-water development, carbonate-rock aquifers in southern Nevada and southeastern California

    USGS Publications Warehouse

    Burbey, T.J.

    1997-01-01

    Seventeen hydrographic areas in southern Nevada were assessed for the ground-water development potential of the underlying carbonate-rock aquifers on the basis of geologic and hydrologic information developed as part of the Nevada Carbonate Aquifers Study and information compiled from previous investigations. All selected areas lie within a miogeoclinal belt where thick accumulations of carbonate rock followed by major episodes of compression and extension have greatly modified the region. Most of the selected hydrographic areas lie within the less extended terranes; however, several areas, or parts of areas, lie within severely extended terranes where carbonate rocks have been greatly thinned, or where deformed blocks of carbonate rock are discontinuous and isolated from surrounding carbonate rock aquifers. Three principal criteria were used to assess the development potential of each selected hydrographic area. These quantitative criteria are: (1) depth to water, (2) depth to and thickness of carbonate rocks, and (3) water quality. Other site-specific factors, such as accessibility and potential effects of ground-water development, are also discussed. Results suggest that sites with high potential for development may be scarce in southern Nevada. Many areas described as favorable on the basis of the three quantitative criteria were deemed unfavorable on the basis of possible short- and long-term effects associated with development and on the amount of available data used to make the assessment. The most favorable sites may be in more severely extended terranes, where development of isolated blocks (of carbonate-rock aquifer material) would be less likely to affect neighboring areas.

  8. Simulation of ground-water flow in the Intermediate and Floridan aquifer systems in Peninsular Florida

    USGS Publications Warehouse

    Sepulveda, Nicasio

    2002-01-01

    A numerical model of the intermediate and Floridan aquifer systems in peninsular Florida was used to (1) test and refine the conceptual understanding of the regional ground-water flow system; (2) develop a data base to support subregional ground-water flow modeling; and (3) evaluate effects of projected 2020 ground-water withdrawals on ground-water levels. The four-layer model was based on the computer code MODFLOW-96, developed by the U.S. Geological Survey. The top layer consists of specified-head cells simulating the surficial aquifer system as a source-sink layer. The second layer simulates the intermediate aquifer system in southwest Florida and the intermediate confining unit where it is present. The third and fourth layers simulate the Upper and Lower Floridan aquifers, respectively. Steady-state ground-water flow conditions were approximated for time-averaged hydrologic conditions from August 1993 through July 1994 (1993-94). This period was selected based on data from Upper Floridan a quifer wells equipped with continuous water-level recorders. The grid used for the ground-water flow model was uniform and composed of square 5,000-foot cells, with 210 columns and 300 rows.

  9. Hydrogeology and the distribution of salinity in the Floridan aquifer system, Palm Beach County, Florida

    USGS Publications Warehouse

    Reese, R.S.; Memberg, S.J.

    2000-01-01

    The virtually untapped Floridan aquifer system is considered to be a supplemental source of water for public use in the highly populated coastal area of Palm Beach County. A recent study was conducted to delineate the distribution of salinity in relation to the local hydrogeology and assess the potential processes that might control (or have affected) the distribution of salinity in the Floridan aquifer system. The Floridan aquifer system in the study area consists of the Upper Floridan aquifer, middle confining unit, and Lower Floridan aquifer and ranges in age from Paleocene to Oligocene. Included at its top is part of a lowermost Hawthorn Group unit referred to as the basal Hawthorn unit. The thickness of this basal unit is variable, ranging from about 30 to 355 feet; areas where this unit is thick were paleotopographic lows during deposition of the unit. The uppermost permeable zones in the Upper Floridan aquifer occur in close association with an unconformity at the base of the Hawthorn Group; however, the highest of these zones can be up in the basal unit. A dolomite unit of Eocene age generally marks the top of the Lower Floridan aquifer, but the top of this dolomite unit has a considerable altitude range: from about 1,200 to 2,300 feet below sea level. Additionally, where the dolomite unit is thick, its top is high and the middle confining unit of the Floridan aquifer system, as normally defined, probably is not present. An upper zone of brackish water and a lower zone of water with salinity similar to that of seawater (saline-water zone) are present in the Floridan aquifer system. The brackish-water and saline-water zones are separated by a transition zone (typically 100 to 200 feet thick) in which salinity rapidly increases with depth. The transition zone was defined by using a salinity of 10,000 mg/L (milligrams per liter) of dissolved-solids concentration (about 5,240 mg/L of chloride concentration) at its top and 35,000 mg/L of dissolved

  10. Conceptual and numerical models of the glacial aquifer system north of Aberdeen, South Dakota

    USGS Publications Warehouse

    Marini, Katrina A.; Hoogestraat, Galen K.; Aurand, Katherine R.; Putnam, Larry D.

    2012-01-01

    This U.S. Geological Survey report documents a conceptual and numerical model of the glacial aquifer system north of Aberdeen, South Dakota, that can be used to evaluate and manage the city of Aberdeen's water resources. The glacial aquifer system in the model area includes the Elm, Middle James, and Deep James aquifers, with intervening confining units composed of glacial till. The Elm aquifer ranged in thickness from less than 1 to about 95 feet (ft), with an average thickness of about 24 ft; the Middle James aquifer ranged in thickness from less than 1 to 91 ft, with an average thickness of 13 ft; and the Deep James aquifer ranged in thickness from less than 1 to 165 ft, with an average thickness of 23 ft. The confining units between the aquifers consisted of glacial till and ranged in thickness from 0 to 280 ft. The general direction of groundwater flow in the Elm aquifer in the model area was from northwest to southeast following the topography. Groundwater flow in the Middle James aquifer was to the southeast. Sparse data indicated a fairly flat potentiometric surface for the Deep James aquifer. Horizontal hydraulic conductivity for the Elm aquifer determined from aquifer tests ranged from 97 to 418 feet per day (ft/d), and a confined storage coefficient was determined to be 2.4x10-5. Estimates of the vertical hydraulic conductivity of the sediments separating the Elm River from the Elm aquifer, determined from the analysis of temperature gradients, ranged from 0.14 to 2.48 ft/d. Average annual precipitation in the model area was 19.6 inches per year (in/yr), and agriculture was the primary land use. Recharge to the Elm aquifer was by infiltration of precipitation through overlying outwash, lake sediments, and glacial till. The annual recharge for the model area, calculated by using a soil-water-balance method for water year (WY) 1975-2009, ranged from 0.028 inch in WY 1980 to 4.52 inches in WY 1986, with a mean of 1.56 inches. The annual potential

  11. Historical potentiometric surface of the Edwards-Trinity aquifer system and contiguous hydraulically connected units, west-central Texas

    USGS Publications Warehouse

    Bush, Peter W.; Ardis, Ann F.; Wynn, Kirby H.

    1993-01-01

    The purpose of this report is to present a potentiometric-surface map of the principal aquifers of the Edwards-Trinity aquifer system based on the earliest available data; to explain in general terms what the potentiometric surface represents relative to rainfall conditions and ground-water withdrawals; and to discuss the major factors that control the configuration of the potentiometric surface.

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

    USGS Publications Warehouse

    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

  13. Geohydrology and model analysis of stream-aquifer system along the Arkansas River in Kearny and Finney Counties, southwestern Kansas

    USGS Publications Warehouse

    Dunlap, L.E.; Lindgren, Richard J.; Sauer, C.G.

    1985-01-01

    A study was made, in cooperation with the Division of Water Resources, Kansas State Board of Agriculture, to determine geohydrologic conditions in an area comprising nearly 850,000 acres along the Arkansas River valley in Kearny and Finney Counties, southwestern Kansas. The Arkansas River meanders atop and interacts hydraulically with the area's multilayered, unconsolidated aquifer system. Declines in static water levels in wells in the heavily pumped lower aquifer ranged from 20 to 80 feet during 1974-80. The river is dry in much of the area. A digital computer model was calibrated to simulate the trends of historic water levels. Simulated 1974-80 conditions depicted an average annual recharge to the unconsolidated aquifer system of 66,900 acre-feet from precipitation and 36,200 acre-feet from river and canal seepage and boundary inflow. Simulated average annual discharge consisted of 634,800 acre-feet from pumpage and boundary outflow. Simulated average annual recharge to the unconsolidated aquifer system was 531,700 acre-feet less than average annual discharge, indicating the ground-water resource is currently (1982) being mined in the study area. Simulation also indicated that there would be sufficient saturated thickness in 2005 for irrigation if 1980 hydrologic conditions continued. Seepage losses from the Arkansas River and irrigation canals are a major source of recharge to the unconsolidated aquifer system. Therefore, the amount of flow in the Arkansas River would be important in determining the rate of future water-level declines in the study area. Streamflow seepage losses could be decreased by (1) decreasing the number of wells pumping in the study area in order to reduce downward leakage from the valley aquifer, or (2) increasing streamflow discharge in order to recharge the valley aquifer. The rate and direction of flow between the river and the valley aquifer depend on the hydraulic conductivity of the streambed and the hydraulic gradient between the

  14. Hydrogeology and hydrologic conditions of the Northern Atlantic Coastal Plain aquifer System from Long Island, New York, to North Carolina

    USGS Publications Warehouse

    Masterson, John P.; Pope, Jason P.; Monti, Jack; Nardi, Mark R.; Finkelstein, Jason S.; McCoy, Kurt J.

    2013-11-14

    Updates to the regional hydrologic budget include revised estimates of aquifer recharge, water use and streamflow data. Inflow to the aquifer system of about 20,000 million gallons per day (Mgal/d) includes 19,600 Mgal/d from recharge from precipitation, 200 Mgal/d of recharge from wastewater via onsite domestic septic systems, and 200 Mgal/d from the release of water from aquifer storage. Outflow from the aquifer system includes groundwater discharge to streams (11,900 Mgal/d), groundwater withdrawals (1,500 Mgal/d), and groundwater discharge to coastal waters (6,600 Mgal/d). A numerical modeling analysis is required to improve this hydrologic budget calculation and to forecast future changes in water levels and aquifer storage caused by groundwater withdrawals, land-use changes, and the effects of climate variability and change.

  15. Groundwater thermal-effective injection systems in shallow aquifers: possible alternatives to vertical water wells

    NASA Astrophysics Data System (ADS)

    Lo Russo, Stefano; Taddia, Glenda; Cerino Abdin, Elena

    2014-05-01

    Urbanized areas have environmental features that may influence the development of low-enthalpy geothermal systems and the choice of the most suitable among the available (roughly earth-coupled closed-loop and groundwater open-loop type). In particular, if compared to less anthropized areas, some characteristic urban elements require particular attention: underground extensive use, contamination of groundwater, interference between the systems, authorization procedures and planning restrictions, the competition with cogeneration systems and the impact on emissions of pollutants. In this general context, the increasing implementation in several areas of the world of the open-loop groundwater heat pumps technology which discharge into the aquifer for cooling and heating buildings, could potentially cause, even in the short term, a significant environmental impact associated with thermal interference with groundwater, particularly in the shallow aquifers. The discharge of water at different temperatures compared to baseline (warmer in summer and colder in winter) poses a number of problems in relation to the potential functionality of many existing situations of use of the groundwater (drinking water wells, agricultural, industrial, etc.). In addition, there may be cases of interference between systems, especially in the more densely urbanized areas. Appropriate hydrogeological investigations should be performed for the characterization of the main hydrogeological parameters of the subsoil at the considered site in order to minimize the environmental impact of discharges into aquifers. The current Italian legislation related to withdrawals and discharges into aquifers designs a framework suitable for the protection of groundwater and induce deciding the best configuration of the plant with a case by case approach. An increased contact area between the dispersant system and the ground makes it possible to affect a greater volume of aquifer and, consequently, reduce the

  16. Conjunctive-management models for sustained yield of stream-aquifer systems

    USGS Publications Warehouse

    Barlow, P.M.; Ahlfeld, D.P.; Dickerman, D.C.

    2003-01-01

    Conjunctive-management models that couple numerical simulation with linear optimization were developed to evaluate trade-offs between groundwater withdrawals and streamflow depletions for alluvial-valley stream-aquifer systems representative of those of the northeastern United States. A conjunctive-management model developed for a hypothetical stream-aquifer system was used to assess the effect of interannual hydrologic variability on minimum monthly streamflow requirements. The conjunctive-management model was applied to the Hunt-Annaquatucket-Pettaquamscutt stream-aquifer system of central Rhode Island. Results show that it is possible to increase the amount of current withdrawal from the aquifer by as much as 50% by modifying current withdrawal schedules, modifying the number and configuration of wells in the supply-well network, or allowing increased streamflow depletion in the Annaquatucket and Pettaquamscutt rivers. Alternatively, it is possible to reduce current rates of streamflow depletion in the Hunt River by as much as 35% during the summer, but such reductions would result increases in groundwater withdrawals.

  17. Geochemical impacts of groundwater heat pump systems in an urban alluvial aquifer with evaporitic bedrock.

    PubMed

    Garrido Schneider, Eduardo A; García-Gil, Alejandro; Vázquez-Suñè, Enric; Sánchez-Navarro, José Á

    2016-02-15

    In the last decade, there has been an extensive use of shallow geothermal exploitations in urban environments. Although the thermal interference between exploitations has been recently studied, there is a lack of knowledge regarding the geochemical impacts of those systems on the aquifers where they are installed. Groundwater flow line scale and well-doublet scale research work has been conducted at city scale to quantify the geochemical interaction of shallow geothermal exploitations with the environment. A comprehensive analysis was conducted on data obtained from a monitoring network specifically designed to control and develop aquifer policies related to thermal management of the aquifer. The geochemical impacts were evaluated from a thermodynamic point of view by means of saturation index (SI) calculations with respect to the different mineral species considered in the system. The results obtained indicate limited geochemical interaction with the urban environment in most of the situations. However, there are some cases where the interaction of the groundwater heat pump installations with the evaporitic bedrock resulted in the total disablement of the exploitation system operation wells. The application of the tool proposed proved to be pragmatic in the evaluation of geochemical impacts. Injection of water into the aquifer can trigger an important bedrock gypsum and halite dissolution process that is partly responsible for scaling in well casing pipes and collapse of the terrain in the vicinity of injection wells.

  18. System Dynamics to Climate-Driven Water Budget Analysis in the Eastern Snake Plains Aquifer

    NASA Astrophysics Data System (ADS)

    Ryu, J.; Contor, B.; Wylie, A.; Johnson, G.; Allen, R. G.

    2010-12-01

    Climate variability, weather extremes and climate change continue to threaten the sustainability of water resources in the western United States. Given current climate change projections, increasing temperature is likely to modify the timing, form, and intensity of precipitation events, which consequently affect regional and local hydrologic cycles. As a result, drought, water shortage, and subsequent water conflicts may become an increasing threat in monotone hydrologic systems in arid lands, such as the Eastern Snake Plain Aquifer (ESPA). The ESPA, in particular, is a critical asset in the state of Idaho. It is known as the economic lifeblood for more than half of Idaho’s population so that water resources availability and aquifer management due to climate change is of great interest, especially over the next few decades. In this study, we apply system dynamics as a methodology with which to address dynamically complex problems in ESPA’s water resources management. Aquifer recharge and discharge dynamics are coded in STELLA modeling system as input and output, respectively to identify long-term behavior of aquifer responses to climate-driven hydrological changes.

  19. Generalized potentiometric surface, estimated depth to water, and estimated saturated thickness of the High Plains aquifer system, March–June 2009, Laramie County, Wyoming

    USGS Publications Warehouse

    Bartos, Timothy T.; Hallberg, Laura L.

    2011-01-01

    The High Plains aquifer system, commonly called the High Plains aquifer in many publications, is a nationally important water resource that underlies a 111-million-acre area (173,000 square miles) in parts of eight States including Wyoming. Through irrigation of crops with groundwater from the High Plains aquifer system, the area that overlies the aquifer system has become one of the major agricultural regions in the world. In addition, the aquifer system also serves as the primary source of drinking water for most residents of the region. The High Plains aquifer system is one of the largest aquifers or aquifer systems in the world. The High Plains aquifer system underlies an area of 8,190 square miles in southeastern Wyoming. Including Laramie County, the High Plains aquifer system is present in parts of five counties in southeastern Wyoming. The High Plains aquifer system underlies 8 percent of Wyoming, and 5 percent of the aquifer system is located within the State. Based on withdrawals for irrigation, public supply, and industrial use in 2000, the High Plains aquifer system is the most utilized source of groundwater in Wyoming. With the exception of the Laramie Mountains in western Laramie County, the High Plains aquifer system is present throughout Laramie County. In Laramie County, the High Plains aquifer system is the predominant groundwater resource for agricultural (irrigation), municipal, industrial, and domestic uses. Withdrawal of groundwater for irrigation (primarily in the eastern part of the county) is the largest use of water from the High Plains aquifer system in Laramie County and southeastern Wyoming. Continued interest in groundwater levels in the High Plains aquifer system in Laramie County prompted a study by the U.S. Geological Survey in cooperation with the Wyoming State Engineer's Office to update the potentiometric-surface map of the aquifer system in Laramie County. Groundwater levels were measured in wells completed in the High Plains

  20. Major geochemical processes in the evolution of carbonate-Aquifer systems

    USGS Publications Warehouse

    Hanshaw, B.B.; Back, W.

    1979-01-01

    -reefs, where reflux dolomites may form, highly alkaline, on-shore and continental lakes, and sabkha flats; these dolomites are typically associated with evaporite minerals. However, these processes cannot account for most of the regionally extensive dolomites in the geologic record. A major environment of regional dolomitization is in the mixing zone (zone of dispersion) where profound changes in mineralogy and redistribution of porosity and permeability occur from the time of early emergence and continuing through the time when the rocks are well-developed aquifers. The reactions and processes, in response to mixing waters of differing chemical composition, include dissolution and precipitation of carbonate minerals in addition to dolomitization. An important control on permeability distribution in a mature aquifer system is the solution of dolomite with concomitant precipitation of calcite in response to gypsum dissolution (dedolomitization). Predictive models developed by mass-transfer calculations demonstrate the controlling reactions in aquifer systems through the constraints of mass balance and chemical equilibrium. An understanding of the origin, chemistry, mineralogy and environments of deposition and accumulation of carbonate minerals together with a comprehension of diagenetic processes that convert the sediments to rocks and geochemical, tectonic and hydrologic phenomena that create voids are important to hydrologists. With this knowledge, hydrologists are better able to predict porosity and permeability distribution in order to manage efficiently a carbonate-aquifer system. ?? 1979.

  1. An Aquifer Storage and Recovery system with reclaimed wastewater to preserve native groundwater resources in El Paso, Texas.

    PubMed

    Sheng, Zhuping

    2005-06-01

    The traditional concept of Aquifer Storage and Recovery (ASR) has been emphasized and extensively applied for water resources conservation in arid and semi-arid regions using groundwater systems as introduced in Pyne's book titled Groundwater Recharge and Wells. This paper extends the ASR concept to an integrated level in which either treated or untreated surface water or reclaimed wastewater is stored in a suitable aquifer through a system of spreading basins, infiltration galleries and recharge wells; and part or all of the stored water is recovered through production wells, dual function recharge wells, or by streams receiving increased discharge from the surrounding recharged aquifer as needed. In this paper, the author uses the El Paso Water Utilities (EPWU) ASR system for injection of reclaimed wastewater into the Hueco Bolson aquifer as an example to address challenges and resolutions faced during the design and operation of an ASR system under a new ASR system definition. This new ASR system concept consists of four subsystems: source water, storage space-aquifer, recharge facilities and recovery facilities. Even though facing challenges, this system has successfully recharged approximately 74.7 million cubic meters (19.7 billion gallons) of reclaimed wastewater into the Hueco Bolson aquifer through 10 recharge wells in the last 18 years. This ASR system has served dual purposes: reuse of reclaimed wastewater to preserve native groundwater, and restoration of groundwater by artificial recharge of reclaimed wastewater into the Hueco Bolson aquifer.

  2. Modeling complex aquifer systems: a case study in Baton Rouge, Louisiana (USA)

    NASA Astrophysics Data System (ADS)

    Pham, Hai V.; Tsai, Frank T.-C.

    2017-01-01

    This study targets two challenges in groundwater model development: grid generation and model calibration for aquifer systems that are fluvial in origin. Realistic hydrostratigraphy can be developed using a large quantity of well log data to capture the complexity of an aquifer system. However, generating valid groundwater model grids to be consistent with the complex hydrostratigraphy is non-trivial. Model calibration can also become intractable for groundwater models that intend to match the complex hydrostratigraphy. This study uses the Baton Rouge aquifer system, Louisiana (USA), to illustrate a technical need to cope with grid generation and model calibration issues. A grid generation technique is introduced based on indicator kriging to interpolate 583 wireline well logs in the Baton Rouge area to derive a hydrostratigraphic architecture with fine vertical discretization. Then, an upscaling procedure is developed to determine a groundwater model structure with 162 layers that captures facies geometry in the hydrostratigraphic architecture. To handle model calibration for such a large model, this study utilizes a derivative-free optimization method in parallel computing to complete parameter estimation in a few months. The constructed hydrostratigraphy indicates the Baton Rouge aquifer system is fluvial in origin. The calibration result indicates hydraulic conductivity for Miocene sands is higher than that for Pliocene to Holocene sands and indicates the Baton Rouge fault and the Denham Springs-Scotlandville fault to be low-permeability leaky aquifers. The modeling result shows significantly low groundwater level in the "2,000-foot" sand due to heavy pumping, indicating potential groundwater upward flow from the "2,400-foot" sand.

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

    PubMed

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

    2015-12-15

    Groundwater within the coastal aquifer systems of the Daweijia area in northeastern China is characterized by a large of variations (33-521mg/L) in NO3(-) concentrations. Elevated nitrate concentrations, in addition to seawater intrusion in the Daweijia well field, both attributable to anthropogenic activities, may impact future water-management practices. Chemical and stable isotopic (δ(18)O, δ(2)H) analysis, (3)H and CFCs methods were applied to provide a better understanding of the relationship between the distribution of groundwater mean residence time (MRT) and nitrate transport, and to identify sources of nitrate concentrations in the complex coastal aquifer systems. There is a relatively narrow range of isotopic composition (ranging from -8.5 to -7.0‰) in most groundwater. Generally higher tritium contents observed in the wet season relative to the dry season may result from rapid groundwater circulation in response to the rainfall through the preferential flow paths. In the well field, the relatively increased nitrate concentrations of groundwater, accompanied by the higher tritium contents in the wet season, indicate the nitrate pollution can be attributed to domestic wastes. The binary exponential and piston-flow mixing model (BEP) yielded feasible age distributions based on the conceptual model. The good inverse relationship between groundwater MRTs (92-467years) and the NO3(-) concentrations in the shallow Quaternary aquifers indicates that elevated nitrate concentrations are attributable to more recent recharge for shallow groundwater. However, there is no significant relationship between the MRTs (8-411years) and the NO3(-) concentrations existing in the carbonate aquifer system, due to the complex hydrogeological conditions, groundwater age distributions and the range of contaminant source areas. Nitrate in the groundwater system without denitrification effects could accumulate and be transported for tens of years, through the complex carbonate

  4. Investigation of aquifer-system compaction in the Hueco basin, El Paso, Texas, USA

    USGS Publications Warehouse

    Heywood, Charles

    1995-01-01

    The Pleistocene geologic history of the Rio Grande valley in the Hueco basin included a cycle of sediment erosion and re-aggradation, resulting in unconformable stratification of sediment of contrasting compressibility and stress history. Since the 1950s large groundwater withdrawals have resulted in significant water-level declines and associated land subsidence. Knowledge of the magnitude and variation of specific storage is needed for developing predictive models of subsidence and groundwater flow simulations. Analyses of piezometric and extensometric data in the form of stress-strain diagrams from a 16 month period yield in situ measurements of aquifer-system compressibility across two discrete aquifer intervals. The linear elastic behaviour of the deeper interval indicates over-consolidation of basin deposits, probably resulting from deeper burial depth before the middle Pleistocene. By contrast, the shallow aquifer system displays an inelastic component, suggesting pre-consolidation stress not significantly greater than current effective stress levels for a sequence of late Pleistocene clay. Harmonic analyses of the piezometric response to earth tides in two water-level piezometers provide an independent estimate of specific storage of aquifer sands.

  5. A quantitative analysis of hydraulic interaction processes in stream-aquifer systems

    PubMed Central

    Wang, Wenke; Dai, Zhenxue; Zhao, Yaqian; Li, Junting; Duan, Lei; Wang, Zhoufeng; Zhu, Lin

    2016-01-01

    The hydraulic relationship between the stream and aquifer can be altered from hydraulic connection to disconnection when the pumping rate exceeds the maximum seepage flux of the streambed. This study proposes to quantitatively analyze the physical processes of stream-aquifer systems from connection to disconnection. A free water table equation is adopted to clarify under what conditions a stream starts to separate hydraulically from an aquifer. Both the theoretical analysis and laboratory tests have demonstrated that the hydraulic connectedness of the stream-aquifer system can reach a critical disconnection state when the horizontal hydraulic gradient at the free water surface is equal to zero and the vertical is equal to 1. A boundary-value problem for movement of the critical point of disconnection is established for an analytical solution of the inverted water table movement beneath the stream. The result indicates that the maximum distance or thickness of the inverted water table is equal to the water depth in the stream, and at a steady state of disconnection, the maximum hydraulic gradient at the streambed center is 2. This study helps us to understand the hydraulic phenomena of water flow near streams and accurately assess surface water and groundwater resources. PMID:26818442

  6. A quantitative analysis of hydraulic interaction processes in stream-aquifer systems.

    PubMed

    Wang, Wenke; Dai, Zhenxue; Zhao, Yaqian; Li, Junting; Duan, Lei; Wang, Zhoufeng; Zhu, Lin

    2016-01-28

    The hydraulic relationship between the stream and aquifer can be altered from hydraulic connection to disconnection when the pumping rate exceeds the maximum seepage flux of the streambed. This study proposes to quantitatively analyze the physical processes of stream-aquifer systems from connection to disconnection. A free water table equation is adopted to clarify under what conditions a stream starts to separate hydraulically from an aquifer. Both the theoretical analysis and laboratory tests have demonstrated that the hydraulic connectedness of the stream-aquifer system can reach a critical disconnection state when the horizontal hydraulic gradient at the free water surface is equal to zero and the vertical is equal to 1. A boundary-value problem for movement of the critical point of disconnection is established for an analytical solution of the inverted water table movement beneath the stream. The result indicates that the maximum distance or thickness of the inverted water table is equal to the water depth in the stream, and at a steady state of disconnection, the maximum hydraulic gradient at the streambed center is 2. This study helps us to understand the hydraulic phenomena of water flow near streams and accurately assess surface water and groundwater resources.

  7. A quantitative analysis of hydraulic interaction processes in stream-aquifer systems

    SciTech Connect

    Wang, Wenke; Dai, Zhenxue; Zhao, Yaqian; Li, Junting; Duan, Lei; Wang, Zhoufeng; Zhu, Lin

    2016-01-28

    The hydraulic relationship between the stream and aquifer can be altered from hydraulic connection to disconnection when the pumping rate exceeds the maximum seepage flux of the streambed. This study proposes to quantitatively analyze the physical processes of stream-aquifer systems from connection to disconnection. A free water table equation is adopted to clarify under what conditions a stream starts to separate hydraulically from an aquifer. Both the theoretical analysis and laboratory tests have demonstrated that the hydraulic connectedness of the stream-aquifer system can reach a critical disconnection state when the horizontal hydraulic gradient at the free water surface is equal to zero and the vertical is equal to 1. A boundary-value problem for movement of the critical point of disconnection is established for an analytical solution of the inverted water table movement beneath the stream. The result indicates that the maximum distance or thickness of the inverted water table is equal to the water depth in the stream, and at a steady state of disconnection, the maximum hydraulic gradient at the streambed center is 2. In conclusion, this study helps us to understand the hydraulic phenomena of water flow near streams and accurately assess surface water and groundwater resources.

  8. A quantitative analysis of hydraulic interaction processes in stream-aquifer systems

    DOE PAGES

    Wang, Wenke; Dai, Zhenxue; Zhao, Yaqian; ...

    2016-01-28

    The hydraulic relationship between the stream and aquifer can be altered from hydraulic connection to disconnection when the pumping rate exceeds the maximum seepage flux of the streambed. This study proposes to quantitatively analyze the physical processes of stream-aquifer systems from connection to disconnection. A free water table equation is adopted to clarify under what conditions a stream starts to separate hydraulically from an aquifer. Both the theoretical analysis and laboratory tests have demonstrated that the hydraulic connectedness of the stream-aquifer system can reach a critical disconnection state when the horizontal hydraulic gradient at the free water surface is equalmore » to zero and the vertical is equal to 1. A boundary-value problem for movement of the critical point of disconnection is established for an analytical solution of the inverted water table movement beneath the stream. The result indicates that the maximum distance or thickness of the inverted water table is equal to the water depth in the stream, and at a steady state of disconnection, the maximum hydraulic gradient at the streambed center is 2. In conclusion, this study helps us to understand the hydraulic phenomena of water flow near streams and accurately assess surface water and groundwater resources.« less

  9. Isotope geochemistry and modelling of the multi-aquifer system in the eastern part of Lithuania

    NASA Astrophysics Data System (ADS)

    Mokrik, Robert; Juodkazis, Vytautas; Štuopis, Anicetas; Mažeika, Jonas

    2014-06-01

    A steady-state groundwater flow model of three Quaternary intertill aquifers in the eastern part of Lithuania has been compiled. The distinction of separate modelled layers is based on hydraulic and isotope-hydrochemistry data criteria. 3H data were used to estimate the corrected groundwater age and were coupled with a groundwater-flow-dynamics model of the Quaternary aquifer system along a cross-section flow pathway from the Baltic Upland recharge area in eastern Lithuania towards the discharge area in the lowlands near the city of Kaunas in central Lithuania. The bicarbonate content in groundwater (214-462 mg/l) increases downgradient towards the lowland area. The other major constituents and total dissolved solids (TDS) have a trend analogous to the bicarbonate. The 14C activity of dissolved inorganic carbon (DIC) in the groundwater ranges from 41.4 to 85.7 pMC. With aquifer-system depth, active precipitation of aqueous solution takes place by dissolving minerals of calcite and dolomite and leakage of "old" groundwater from lower aquifers; the process is also traced by lower 14C and 3H activities and by more positive δ18O values in lowland areas.

  10. Planning report for the southwest alluvial basins (east) regional aquifer-system analysis, parts of Colorado, New Mexico, and Texas

    USGS Publications Warehouse

    Wilkins, D.W.; Scott, W.B.; Kaehler, C.A.

    1980-01-01

    The study of the Southwest alluvial basins (east) will involve an analysis of the regional aquifer system in parts of Colorado, New Mexico, and Texas. This area has been divided into 22 basins. The study of the alluvial aquifer-system will be made in the following stages: (1) project planning, (2) literature searches, (3) compiling existing data, (4) data collection, (5) basin modeling, (6) regional aquifer modeling, and (7) reports. The regional aquifer study will be accomplished through studying each of the 22 basins. Data compilation and limited data collection will be part of each basin study. Digital computer models will be made for those basins where data are sufficient. A regional aquifer model will be developed from the basin models. In addition to this report, there will be basin hydrology reports and the final regional report. Included in the final report will be a description of the regional hydrology and geology. (USGS)

  11. The San Andreas Fault System, California

    USGS Publications Warehouse

    Wallace, Robert E.

    1990-01-01

    Maps of northern and southern California printed on flyleaf inside front cover and on adjacent pages show faults that have had displacement within the past 2 million years. Those that have had displacement within historical time are shown in red. Bands of red tint emphasize zones of historical displacement; bands of orange tint emphasize major faults that have had Quaternary displacement before historical time. Faults are dashed where uncertain, dotted where covered by sedimentary deposits, and queried when doubtful. Arrows indicate direction of relative movement; sawteeth on upper plate of thrust fault. These maps are reproductions, in major part, of selected plates from the "Fault Map of California," published in 1975 by the California Division of Mines and Geology at a scale of 1:750,000; the State map was compiled and data interpreted by Charles W. Jennings. New data about faults, not shown on the 1975 edition, required modest revisions, primarily additions however, most of the map was left unchanged because the California Division of Mines and Geology is currently engaged in a major revision and update of the 1975 edition. Because of the reduced scale here, names of faults and places were redrafted or omitted. Faults added to the reduced map are not as precise as on the original State map, and the editor of this volume selected certain faults and omitted others. Principal regions for which new information was added are the region north of the San Francisco Bay area and the offshore regions.Many people have contributed to the present map, but the editor is solely responsible for any errors and omissions. Among those contributing informally, but extensively, and the regions to which each contributed were G.A. Carver, onland region north of lat 40°N.; S.H. Clarke, offshore region north of Cape Mendocino; R.J. McLaughlin, onland region between lat 40°00' and 40°30' N. and long 123°30' and 124°30' W.; D.S. McCulloch offshore region between lat 35° and 40° N

  12. Salinization processes in a coastal aquifer system (Siracusa, Italy)

    NASA Astrophysics Data System (ADS)

    Rapti Caputo, D.; Vaccaro, C.

    2003-04-01

    The Syracuse area (Southeastern Sicily, Italy) is famous since ancient times for its natural springs, like Aretusa and Ciane, as well as for the hydraulic management handicraft know from 480 B.C. Unfortunately, the recent hyper-exploitation of the underground water resources and the concomitant decrease of the precipitations caused a general lowering of the piezometric level of the aquifers therefore enhancing the intrusion of marine salty waters. In the present work, numerous hydrochemical parameters have been investigated, among which the pH, the total dissolved solid, the electric conductivity, the temperature and the concentration of Ca, Mg, Na, K, HCO3, Cl and SO4. The data have been collected from five well fields located at different distances from the coast. Analyses have been performed in order to understand the relationships between the intense exploitation and the geochemical characteristics of the underground water resources. Our results obtained by applying classical geochemical methodologies integrated with techniques of multivariate statistics emphasise, firstly, the predominance of the Ca-HCO3 hydrochemical facies. Secondly, we could determine the evolution of mixing phenomena between salty and fresh waters approaching the coast line (San Nicola field). This behaviour is mainly associated to the pumping increase. Obviously, this intrusive process characterised by chlorides concentrations larger than 2000 mg/l affects all the coastal natural environment and generates severe problems to the entire aqueduct network.

  13. Assessment of groundwater corrosiveness for unconfined aquifer system at Kalpakkam.

    PubMed

    Sasidhar, P; Vijay Kumar, S B

    2008-10-01

    Groundwater samples from the shallow unconfined aquifer were collected from fifteen borewells in Kalpakkam nuclear plant site and were analysed for various physico-chemical parameters. The pH, temperature, salinity, TDS and EC were measured in the field. The borewell samples were analysed in the laboratory for Ca(2+), Mg(2+), Na(+), Cl(-), CO(2-)(3), HC(O-)(3), N(O-)(3) and SO(2-)(4). The Piper Trilinear diagram showed that majority of the borewell samples fall in Na - Cl +SO(4) type and Na - CO(3)+HCO(3) type. The Cl: HCO3 ratio of some borewell samples are categorized under injuriously contaminated to highly injurious type. The higher salinity levels encountered in some borewells emphasized the need for better understanding of groundwater corrosiveness. Accordingly, the Langeliar saturation Index (SI), Aggressivity index (AI) and Larson ratio (LnR) were evaluated for assessing the corrosive nature of the groundwater. The saline water incursion in the southern part of the study area increased the ionic concentration of Cl(-) and [Formula: see text] that made the groundwater corrosive.

  14. Regional Analysis of Stormwater Runoff for the Placement of Managed Aquifer Recharge Sites in Santa Cruz and Northern Monterey Counties, California

    NASA Astrophysics Data System (ADS)

    Young, K. S.; Beganskas, S.; Fisher, A. T.

    2015-12-01

    We apply a USGS surface hydrology model, Precipitation-Runoff Modeling System (PRMS), to analyze stormwater runoff in Santa Cruz and Northern Monterey Counties, CA with the goal of supplying managed aquifer recharge (MAR) sites. Under the combined threats of multiyear drought and excess drawdown, this region's aquifers face numerous sustainability challenges, including seawater intrusion, chronic overdraft, increased contamination, and subsidence. This study addresses the supply side of this resource issue by increasing our knowledge of the spatial and temporal dynamics of runoff that could provide water for MAR. Ensuring the effectiveness of MAR using stormwater requires a thorough understanding of runoff distribution and site-specific surface and subsurface aquifer conditions. In this study we use a geographic information system (GIS) and a 3-m digital elevation model (DEM) to divide the region's four primary watersheds into Hydrologic Response Units (HRUs), or topographic sub-basins, that serve as discretized input cells for PRMS. We then assign vegetation, soil, land use, slope, aspect, and other characteristics to these HRUs, from a variety of data sources, and analyze runoff spatially using PRMS under varying precipitation conditions. We are exploring methods of linking spatially continuous and high-temporal-resolution precipitation datasets to generate input precipitation catalogs, facilitating analyses of a variety of regimes. To gain an understanding of how surface hydrology has responded to land development, we will also modify our input data to represent pre-development conditions. Coupled with a concurrent MAR suitability analysis, our model results will help screen for locations of future MAR projects and will improve our understanding of how changes in land use and climate impact hydrologic runoff and aquifer recharge.

  15. Integrating Predictive Modeling with Control System Design for Managed Aquifer Recharge and Recovery Applications

    NASA Astrophysics Data System (ADS)

    Drumheller, Z. W.; Regnery, J.; Lee, J. H.; Illangasekare, T. H.; Kitanidis, P. K.; Smits, K. M.

    2014-12-01

    Aquifers around the world show troubling signs of irreversible depletion and seawater intrusion as climate change, population growth, and urbanization led to reduced natural recharge rates and overuse. Scientists and engineers have begun to re-investigate the technology of managed aquifer recharge and recovery (MAR) as a means to increase the reliability of the diminishing and increasingly variable groundwater supply. MAR systems offer the possibility of naturally increasing groundwater storage while improving the quality of impaired water used for recharge. Unfortunately, MAR systems remain wrought with operational challenges related to the quality and quantity of recharged and recovered water stemming from a lack of data-driven, real-time control. Our project seeks to ease the operational challenges of MAR facilities through the implementation of active sensor networks, adaptively calibrated flow and transport models, and simulation-based meta-heuristic control optimization methods. The developed system works by continually collecting hydraulic and water quality data from a sensor network embedded within the aquifer. The data is fed into an inversion algorithm, which calibrates the parameters and initial conditions of a predictive flow and transport model. The calibrated model is passed to a meta-heuristic control optimization algorithm (e.g. genetic algorithm) to execute the simulations and determine the best course of action, i.e., the optimal pumping policy for current aquifer conditions. The optimal pumping policy is manually or autonomously applied. During operation, sensor data are used to assess the accuracy of the optimal prediction and augment the pumping strategy as needed. At laboratory-scale, a small (18"H x 46"L) and an intermediate (6'H x 16'L) two-dimensional synthetic aquifer were constructed and outfitted with sensor networks. Data collection and model inversion components were developed and sensor data were validated by analytical measurements.

  16. Simulation of ground-water flow in the Coastal Plain aquifer system of North Carolina

    USGS Publications Warehouse

    Giese, G.I.; Eimers, J.L.; Coble, R.W.

    1997-01-01

    A three-dimensional finite-difference digital model was used to simulate ground-water flow in the 25,000-square-mile aquifer system of the North Carolina Coastal Plain. The model was developed from a hydrogeologic framework that is based on an alternating sequence of 10 aquifers and 9 confining units, which make up a seaward-thickening wedge of sediments that form the Coastal Plain aquifer system in the State of North Carolina. The model was calibrated by comparing observed and simulated water levels. The model calibration was achieved by adjusting model parameters, primarily leakance of confining units and transmissivity of aquifers, until differences between observed and simulated water levels were within acceptable limits, generally within 15 feet. The maximum transmissivity of an individual aquifer in the calibrated model is 200,000 feet squared per day in a part of the Castle Hayne aquifer, which consists predominantly of limestone. The maximum value for simulated vertical hydraulic conductivity in a confining unit was 2.5 feet per day, in a part of the confining unit overlying the upper Cape Fear aquifer. The minimum value was 4.1x10-6 feet per day, in part of the confining unit overlying the lower Cape Fear aquifer. Analysis indicated the model is highly sensitive to changes in transmissivity and leakance near pumping centers; away from pumping centers, the model is only slightly sensitive to changes in transmissivity but is moderately sensitive to changes in leakance. Recharge from precipitation to the surficial aquifer ranges from about 12 inches per year in areas having clay at the surface to about 20 inches per year in areas having sand at the surface. Most of this recharge moves laterally to streams, and only about 1 inch per year moves downward to the confined parts of the aquifer system. Under predevelopment conditions, the confined aquifers were generally recharged in updip interstream areas and discharged through streambeds and in downdip coastward

  17. Hydrogeology and the Distribution and Origin of Salinity in the Floridan Aquifer System, Southeastern Florida

    USGS Publications Warehouse

    Reese, Ronald S.

    1994-01-01

    The Floridan aquifer system in southeastern Florida consists of the Upper Floridan aquifer, the middle confining unit, and the Lower Floridan aquifer. An upper zone of brackish water and a lower zone of water with a salinity similar to that of seawater are present in the Floridan aquifer system. The brackish-water zone is defined as that in which water has a dissolved-solids concentration of less than 10,000 milligrams per liter (chloride concentration less than about 5,240 milligrams per liter), and water in the the saline-water zone has a dissolved solids concentration of about 35,000 milligrams per liter (about 18,900 milligrams per liter chloride concentration). The brackish-water and saline-water zones are separated by a transitional zone, typically 100 feet thick, in which salinity increases abruptly with depth. The base of the brackish-water zone lies within the Upper Floridan aquifer along the coast but extends into the middle confining unit inland. The brackish- water zone is as much as 1,200 feet thick inland, whereas the Upper Floridart aquifer is typically 500 to 600 feet thick. Changes in lithology or permeability do not usually control the position of the boundary between the brackish-water and saline-water zones. Calculations of the depth of a brackish-water and saline-water interface using the Ghyben-Herzberg relation show good agreement between calculated and actual positions of the interface, indicating equilibrium between the zones. Several areas of high salinity with chloride concentrations greater than 3,000 milligrams per liter are present in the upper interval of the brackish-water zone near the coast, and in one of these areas in northeastern Broward County, salinity decreases with depth from the upper to lower interval. The high salinities could be a result of seawater preferentially encroaching into zones of higher permeability in the Upper Flofidan aquifer during Pleistocene high stands of sea level and incomplete flushing of the seawater

  18. Sandia National Laboratories, California Environmental Management System program manual

    SciTech Connect

    Larsen, Barbara L.

    2014-04-01

    The Sandia National Laboratories, California (SNL/CA) Environmental Management System (EMS) Program Manual documents the elements of the site EMS Program. The SNL/CA EMS Program conforms to the International Standard on Environmental Management Systems, ISO 14001:2004 and Department of Energy (DOE) Order 436.1.

  19. Sandia National Laboratories, California Environmental Management System program manual.

    SciTech Connect

    Larsen, Barbara L.

    2013-04-01

    The Sandia National Laboratories, California (SNL/CA) Environmental Management System (EMS) Program Manual documents the elements of the site EMS Program. The SNL/CA EMS Program conforms to the International Standard on Environmental Management Systems, ISO 14001:2004 and Department of Energy (DOE) Order 436.1.

  20. Hydrogeologic framework of the Floridan aquifer system in Florida and in parts of Georgia, South Carolina, and Alabama

    USGS Publications Warehouse

    Miller, James A.

    1986-01-01

    The Floridan aquifer system of the Southeastern United States is comprised of a thick sequence of carbonate rocks that are mostly of Paleocene to early Miocene age and that are hydraulically connected in varying degrees. The aquifer system consists of a single vertically continuous permeable unit updip and of two major permeable zones (the Upper and Lower Floridan aquifers) separated by one of seven middle confining units downdip. Neither the boundaries of the aquifer system or of its component high- and low-permeability zones necessarily conform to either formation boundaries or time-stratigraphic breaks. The rocks that make up the Floridan aquifer system, its upper and lower confining units, and a surficial aquifer have been separated into several chronostratigraphic units. The external and internal geometry of these stratigraphic units is presented on a series of structure contour and isopach maps and by a series of geohydrologic cross sections and a fence diagram. Paleocene through middle Eocene units consist of an updip clastic facies and a downdip carbonate bank facies, that extends progressively farther north and east in progressively younger units. Upper Eocene and Oligocene strata are predominantly carbonate rocks throughout the study area. Miocene and younger strata are mostly clastic rocks. Subsurface data show that some modifications in current stratigraphic nomenclature are necessary. First, the middle Eocene Lake City Limestone cannot be distinguished lithologically or faunally from the overlying middle Eocene Avon Park 'Limestone.' Accordingly, it is proposed that the term Lake City be abandoned and the term Avon Park Formation be applied to the entire middle Eocene carbonate section of peninsular Florida and southeastern Georgia. A reference well section in Levy County, Fla., is proposed for the expanded Avon Park Formation. The Avon Park is called a 'formation' more properly than a 'limestone' because the unit contains rock types other than

  1. The contribution of cluster and discriminant analysis to the classification of complex aquifer systems.

    PubMed

    Panagopoulos, G P; Angelopoulou, D; Tzirtzilakis, E E; Giannoulopoulos, P

    2016-10-01

    This paper presents an innovated method for the discrimination of groundwater samples in common groups representing the hydrogeological units from where they have been pumped. This method proved very efficient even in areas with complex hydrogeological regimes. The proposed method requires chemical analyses of water samples only for major ions, meaning that it is applicable to most of cases worldwide. Another benefit of the method is that it gives a further insight of the aquifer hydrogeochemistry as it provides the ions that are responsible for the discrimination of the group. The procedure begins with cluster analysis of the dataset in order to classify the samples in the corresponding hydrogeological unit. The feasibility of the method is proven from the fact that the samples of volcanic origin were separated into two different clusters, namely the lava units and the pyroclastic-ignimbritic aquifer. The second step is the discriminant analysis of the data which provides the functions that distinguish the groups from each other and the most significant variables that define the hydrochemical composition of the aquifer. The whole procedure was highly successful as the 94.7 % of the samples were classified to the correct aquifer system. Finally, the resulted functions can be safely used to categorize samples of either unknown or doubtful origin improving thus the quality and the size of existing hydrochemical databases.

  2. Analysis of karst aquifer spring flows with a gray system decomposition model.

    PubMed

    Hao, Yonghong; Yeh, Tian-Chyi J; Wang, Yanrong; Zhao, Ying

    2007-01-01

    There are approximately 470,000 km(2) of karst aquifers that feed many large springs in North China. Turbulent flow often exists in these karst aquifers, which means that the classical ground water model based on Darcy's law cannot be applied here. Ground water data are rare for these aquifers. As a consequence, it is difficult to quantitatively investigate ground water flow in these karst systems. The purpose of this study is to develop a parsimonious model that predicts karst spring discharge using gray system theory. In this theory, a white color denotes a system that is completely characterized and a black color represents a system that is totally unknown. A gray system thus describes a complex system whose characteristics are only partially known or known with uncertainty. Using this theory, we investigated the karst spring discharge time series over different time scales. First, we identified three specific components of spring discharge: the long-term trend, periodic variation, and random fluctuation. We then used the gray system model to simulate the long-term trend and obtain periodic variation and random fluctuation components. Subsequently, we developed a predictive model for karst spring discharge. Application of the model to Liulin Springs, a representative example of karst springs in northern China, shows that the model performs well. The predicted results suggest that the Liulin Springs discharge will likely decrease over time, with small fluctuations.

  3. Modelling Contributions of the Local and Regional Groundwater Flow of Managed Aquifer Recharge Activities at Querença-Silves Aquifer System.

    NASA Astrophysics Data System (ADS)

    Costa, Luís; Monteiro, José Paulo; Oliveira, Manuel; Mota, Rogério; Lobo-Ferreira, João Paulo; Martins de Carvalho, José; Martins de Carvalho, Tiago; Agostinho, Rui; Hugman, Rui

    2015-04-01

    The Querença-Silves (QS) aquifer system is one of the most important natural groundwater reservoirs in the Algarve region of southern Portugal. With a surface area of 324 km2, this karst aquifer system is the main source of supply for irrigation as well as an important source of water for the urban supply. Due to the importance given to QS aquifer system by both governmental actors and end users, ongoing research during the last two decades at the University of Algarve has attempted to provide a better understanding of the hydrogeology and hydraulic behavior, which has resulted in the development of regional scale numerical models. The most recent hydrogeological data has been acquired during the ongoing MARSOL project (MARSOL-GA-2013-619120) which aims to demonstrate that Managed Aquifer Recharge (MAR) is a sound, safe and sustainable strategy that can be applied with great confidence in finding solutions to water scarcity in Southern Europe. Within the scope of the project large diameter well injection tests (with and without tracers) as well as geophysical surveys have been carried out in order to determine the infiltration capacity and aquifer properties. The results of which allowed the use of analytical methods to determine local scale values of hydraulic parameters (e.g. hydraulic conductivity and storage coefficient). These values will be compared with results from pre-existing numerical flow and transport models in order to obtain complementary solutions to the problem at local and regional scales. This analysis will contribute to the selection of the most appropriate methods to interpret, reproduce and model the impacts of MAR activities planned within the scope of the MARSOL project. Subsequent to the planned injection tests and, with the support of modelling efforts, the capacity of infiltration of rejected water from water treatment plants or surface storage dams in the large diameter well will be assessed.

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

    NASA Astrophysics Data System (ADS)

    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.

  5. Rapid progression of ocean acidification in the California Current System.

    PubMed

    Gruber, Nicolas; Hauri, Claudine; Lachkar, Zouhair; Loher, Damian; Frölicher, Thomas L; Plattner, Gian-Kasper

    2012-07-13

    Nearshore waters of the California Current System (California CS) already have a low carbonate saturation state, making them particularly susceptible to ocean acidification. We used eddy-resolving model simulations to study the potential development of ocean acidification in this system up to the year 2050 under the Special Report on Emissions Scenarios A2 and B1 scenarios. In both scenarios, the saturation state of aragonite Ω(arag) is projected to drop rapidly, with much of the nearshore region developing summer-long undersaturation in the top 60 meters within the next 30 years. By 2050, waters with Ω(arag) above 1.5 will have largely disappeared, and more than half of the waters will be undersaturated year-round. Habitats along the sea floor will become exposed to year-round undersaturation within the next 20 to 30 years. These projected events have potentially major implications for the rich and diverse ecosystem that characterizes the California CS.

  6. Shallow Aquifer Connectivity and Early Season Water Supply of Seasonal Wetlands and Drainages Leading to Regional Drainage Systems

    NASA Astrophysics Data System (ADS)

    McCarten, N. F.; Harter, T.

    2009-12-01

    The Sacramento and San Joaquin Rivers in the Central Valley, California are recognized being seasonally supplied by early season direct surface water runoff and later season snow melt runoff from their tributaries. In addition, early season water supply to these rivers is derived from precipitation (PPT) that has infiltrated into soils underlain by a near surface aquitard, typically at less than 2 m depth. These shallow perched groundwater systems contribute a potentially substantial amount of water from more than 500,000 hectares of landforms associated with geomorphic terraces underlain by these aquitards. Early season water input to seasonal and perennial drainages is regulated by the hydraulic conductivity of the (clay-) loamy soils and by surface and aquitard slope of the local catchments associated with these old alluvial landforms. Research on these landforms and shallow aquifers has identified a complex PPT and evapotranspiration (ET) sensitive system that includes shallow depressions that seasonally produce water table derived wetlands (“vernal pools”). These wetlands have been recognized for a very high level of plant and invertebrate species diversity including endangered species. In addition, these seasonal wetlands provide migratory feeding areas of birds. Our work on these seasonal perched systems shows that as much as 80 percent of the soil column above the aquitard is saturated, during average to high rainfall years, for up to 90 to 120 days. Where the water table of this perched system intercepts the land surface, vernal pools develop. The perched groundwater drains into seasonal surface drainages that ultimately supply the Sacramento and San Joaquin rivers. At the end of the rainy season, both the vernal pools and the perched aquifer rapidly and synchronously disappear. Once the soil is unsaturated, water flow is vertically upward due to ET. Variably saturated modeling of this system was conducted using HYDRUS 2D/3D. Climate inputs were from

  7. Results from a workshop on research needs for modeling aquifer thermal energy storage systems

    NASA Astrophysics Data System (ADS)

    Drost, M. K.

    1990-08-01

    A workshop an aquifer thermal energy storage (ATES) system modeling was conducted by Pacific Northwest Laboratory (PNL). The goal of the workshop was to develop a list of high priority research activities that would facilitate the commercial success of ATES. During the workshop, participants reviewed currently available modeling tools for ATES systems and produced a list of significant issues related to modeling ATES systems. Participants assigned a priority to each issue on the list by voting and developed a list of research needs for each of four high-priority research areas; the need for a feasibility study model, the need for engineering design models, the need for aquifer characterization, and the need for an economic model. The workshop participants concluded that ATES commercialization can be accelerated by aggressive development of ATES modeling tools and made specific recommendations for that development.

  8. Geochemistry of the Floridan aquifer system in Florida and in parts of Georgia, South Carolina, and Alabama

    USGS Publications Warehouse

    Sprinkle, Craig L.

    1989-01-01

    The chemical quality of the ground water in the Floridan aquifer system is determined primarily by mineral-water interaction. However, some changes in water quality have been imposed by development, particularly near coastal pumping centers. A total of 601 chemical analyses, all from different wells, most completed in the upper part of the aquifer system, were used to describe the variations in water chemistry and to study the processes responsible for observed changes. The Floridan aquifer system is a vertically continuous sequence of Tertiary carbonate rocks that are of generally high permeability and are hydraulically connected in varying degrees. The rocks are principally limestone and dolomite, but they grade into limy sands and clays near the aquifer system's updip limits. Major minerals in the aquifer system are calcite, dolomite, and, locally, gypsum or quartz; minor minerals include apatite, glauconite, and clay minerals such as kaolinite and montmorillonite. Trace amounts of metallic oxides or sulfides are present in some areas. The aquifer system consists of the Upper and Lower Floridan aquifers, separated in most places by a less permeable confining unit that has highly variable hydraulic properties. Only the Upper Floridan aquifer is present throughout the study area. Freshwater enters the aquifer system in outcrop areas located primarily in central Georgia and north-central Florida. Discharge occurs chiefly to streams and springs and, to a lesser extent, directly into the sea. Most of the flow into and out of the system takes place where it is unconfined or where the upper confining unit is thin. Secondary permeability developed by dissolution of aquifer material is most prominent in these areas of dynamic flow. Dissolved-solids concentrations in water from the Upper Floridan aquifer generally range from less than 25 milligrams per liter near outcrops to more than 25,000 milligrams per liter along the coasts. The dominant cations in the ground water

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

    USGS Publications Warehouse

    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.

  10. A digital simulation of the glacial-aquifer system in the northern three-fourths of Brown County, South Dakota

    USGS Publications Warehouse

    Emmons, P.J.

    1990-01-01

    A digital model was developed to simulate groundwater flow in a complex glacial-aquifer system that includes the Elm, Middle James, and Deep James aquifers in South Dakota. The average thickness of the aquifers ranges from 16 to 32 ft and the average hydraulic conductivity ranges from 240 to 300 ft/day. The maximum steady-state recharge to the aquifer system was estimated to be 7.0 in./yr, and the maximum potential steady- state evapotranspiration was estimated to be 35.4 in/yr. Maximum monthly recharge for 1985 ranged from zero in the winter to 2.5 in in May. The potential monthly evapotranspiration for 1985 ranged from zero in the winter to 7.0 in in July. The average difference between the simulated and observed water levels from steady-state conditions (pre-1983) was 0. 78 ft and the average absolute difference was 4.59 ft for aquifer layer 1 (the Elm aquifer) from 22 observation wells and 3.49 ft and 5.10 ft, respectively, for aquifer layer 2 (the Middle James aquifer) from 13 observation wells. The average difference between the simulated and observed water levels from simulated monthly potentiometric heads for 1985 in aquifer layer 1 ranged from -2.54 ft in July to 0.59 ft in May and in aquifer layer 2 ranged from -1.22 ft in April to 4.98 ft in November. Sensitivity analysis of the steady-state model indicates that it is most sensitive to changes in recharge and least sensitive to changes in hydraulic conductivity. (USGS)

  11. Development of a Unified Hydrostratigraphic Framework for the Floridan Aquifer System in Central and Southern Florida

    NASA Astrophysics Data System (ADS)

    Reese, R. S.

    2008-05-01

    The mostly carbonate Floridan aquifer system (FAS) of central and southern Florida is a widely used resource with a complex hydrostratigraphic framework that is managed primarily in a subregional context according to water management jurisdictional boundaries. As use of the FAS increases, a consistent regional hydrostratigraphic framework is needed for effective management across these boundaries. Stratigraphic marker horizons within and near the top of FAS were delineated and mapped to develop a preliminary, correlative stratigraphic framework. This framework was used to identify and determine aquifers, subaquifers, and confining units and map their spatial distribution. These horizons are based on lithologic changes and geophysical log signatures identified in previous studies, and they were extended throughout the study area primarily by correlation of natural gamma-ray logs. The FAS consists of the Upper Floridan aquifer, middle confining unit, and Lower Floridan aquifer. A regional, productive zone is delineated and informally referred to as the Avon Park permeable zone. This zone is present over most of the study area and is characterized by thick units of dolostone with interbedded limestone and high fracture permeability. The zone has been identified in different regions in previous studies, either as the upper part of the Lower Floridan aquifer or as the lower part of the Upper Floridan aquifer. In this study it is generally considered to be within the middle confining unit. Transmissivity of the Avon Park permeable zone, a major source of water supply, generally ranges from less than 1x104 up to 1.6x106 ft2/day, and is greatest in central Florida where dolomite is developed as a major component of the zone. A large area of low transmissivity (less than 105 ft2/day) in southern Florida coincides with an area where limestone is the predominant lithology within the zone. Major uses of the FAS now include withdrawal for public and agricultural supply

  12. Integrated monitoring technologies for the management of a Soil-Aquifer-Treatment (SAT) system

    NASA Astrophysics Data System (ADS)

    Kallioras, Andreas; Kofakis, Petros; Bumberger, Jan; Athanasiou, Georgios; Schimdt, Felix; Apostolopoulos, Georgios; Uzunoglou, Nikolaos; Dietrich, Peter; Schuth, Christoph

    2015-04-01

    Artificial recharge of groundwater has an important role to play in water reuse as treated wastewater effluent can be infiltrated into the ground for aquifer recharge. As the effluent moves through the soil and the aquifer, it undergoes significant quality improvements through physical, chemical, and biological processes in the underground environment. Collectively, these processes and the water quality improvement obtained are called soil-aquifer-treatment (SAT) or geopurification. The pilot site of Lavrion Technological & Cultural Park (LTCP) of the National Technical University of Athens (NTUA), involves the employment of plot infiltration basins at experimental scale, which will be using waters of impaired quality as a recharge source, and hence acting as a Soil-Aquifer-Treatment, SAT, system. Τhe LTCP site will be employed as a pilot SAT system complemented by new technological developments, which will be providing continuous monitoring of the quantitative and qualitative characteristics of infiltrating groundwater through all hydrologic zones (i.e. surface, unsaturated and saturated zone). This will be achieved by the development and installation of an integrated system of prototype sensing technologies, installed on-site, and offering a continuous evaluation of the performance of the SAT system. An integrated approach of the performance evaluation of any operating SAT system should aim at parallel monitoring of all hydrologic zones, proving the sustainability of all involved water quality treatment processes within unsaturated and saturated zone. Hence a prototype system of Time and Frequency Domain Reflectometry (TDR & FDR) sensors is developed and will be installed, in order to achieve continuous quantitative monitoring of the unsaturated zone through the entire soil column down to significant depths below the SAT basin. Additionally, the system contains two different radar-based sensing systems that will be offering (i) identification of preferential

  13. A Regional Strategy for the Assessment and Management of Transboundary Aquifer Systems in the Americas

    NASA Astrophysics Data System (ADS)

    Hanson, R. T.; Rivera, A.; Tujchneider, O.; Guillén, C.; Campos, M.; Da Franca, N.; May, Z.; Aureli, A.

    2015-12-01

    The UNESCO-IHP ISARM-Americas technical committee has developed a regional strategy for the assessment and management of transboundary aquifer systems in the Americas as part of their ongoing cooperative assistance to help neighboring countries sustain water resources and reduce potential conflict. The fourth book in the series of publications sponsored by UNESCO and OAS documents this strategy. The goal of this strategy is the collective understanding, developing, managing, and protecting of the transboundary aquifers in the Americas This strategy includes technical, social, and governance recommendations for an integrated resource management of groundwater based on flexible arrangements that not only manage but also demand social participation in solving problems, consider changes in land use and water use and promote the increase of water sustainability for all transboundary neighbors. The successful implementation of this strategy starts with sharing information of the status and use of land and water as well as intergovernmental partnerships to link science and policy with existing instruments for managing the water resources. International organizations such as UNESCO and OAS also can help facilitate the development of transboundary agreements and establish cooperation on transboundary aquifers between neighbors. The UNESCO-IHP ISARM-Americas technical committee has been successful in creating a network of partners from 24 countries and in translating existing aquifer knowledge into a meaningful strategy for the American hemisphere. The strategy aims to explain and develop the role of science and the informed-decision approach. Examples from North and South America show how the process has begun to develop for selected transboundary aquifers. These include the Milk River basin between the US and Canada, the Rio Grande and Colorado River basins between the US and Mexico, and the Guarani River basin in South America.

  14. Studying the flow dynamics of a karst aquifer system with an equivalent porous medium model.

    PubMed

    Abusaada, Muath; Sauter, Martin

    2013-01-01

    The modeling of groundwater flow in karst aquifers is a challenge due to the extreme heterogeneity of its hydraulic parameters and the duality in their discharge behavior, that is, rapid response of highly conductive karst conduits and delayed drainage of the low-permeability fractured matrix after recharge events. There are a number of different modeling approaches for the simulation of the karst groundwater dynamics, applicable to different aquifer as well as modeling problem types, ranging from continuum models to double continuum models to discrete and hybrid models. This study presents the application of an equivalent porous model approach (EPM, single continuum model) to construct a steady-state numerical flow model for an important karst aquifer, that is, the Western Mountain Aquifer Basin (WMAB), shared by Israel and the West-Bank, using MODFLOW2000. The WMAB was used as a catchment since it is a well-constrained catchment with well-defined recharge and discharge components and therefore allows a control on the modeling approach, a very rare opportunity for karst aquifer modeling. The model demonstrates the applicability of equivalent porous medium models for the simulation of karst systems, despite their large contrast in hydraulic conductivities. As long as the simulated saturated volume is large enough to average out the local influence of karst conduits and as long as transport velocities are not an issue, EPM models excellently simulate the observed head distribution. The model serves as a starting basis that will be used as a reference for developing a long-term dynamic model for the WMAB, starting from the pre-development period (i.e., 1940s) up to date.

  15. Inorganic, isotopic, and organic composition of high-chloride water from wells in a coastal southern California aquifer

    USGS Publications Warehouse

    Izbicki, J.A.; Christensen, A.H.; Newhouse, M.W.; Aiken, G.R.

    2005-01-01

    Chloride concentrations were as high as 230 mg/L in water from the surface discharge of long-screened production wells in Pleasant Valley, Calif., about 100 km NW of Los Angeles. Wells with the higher Cl- concentrations were near faults that bound the valley. Depending on well construction, high-Cl-water from different sources may enter a well at different depths. For example, Cl- concentration in the upper part of some wells completed in overlying aquifers influenced by irrigation return were as high as 220 mg/L, and Cl- concentrations in water sampled within wells at depths greater than 450 m were as high as 500 mg/L. These high-Cl - waters mix within the well during pumping and produce the water sampled at the surface discharge. Changes in the major ion, minor ion, trace element, and ??34S and ??13C isotopic composition of water in wells with depth were consistent with changes resulting from SO4 reduction, precipitation of calcite, and cation exchange. The chemical and isotopic composition of high-Cl- water from deep wells trends towards the composition of oil-field production water from the study area. Chloride concentrations in oil-field production water present at depths 150 m beneath freshwater aquifers were 2200 mg/L, and Cl- concentrations in underlying marine rock were as high as 4400 mg/L. High-Cl - concentrations in water from deeper parts of wells were associated with dissolved organic C composed primarily of hydrophobic neutral compounds believed to be similar to those associated with petroleum in underlying deposits. These compounds would not be apparent using traditional sampling techniques and would not be detected using analytical methods intended to measure contamination.

  16. Integrated monitoring technologies for the management of a Soil-Aquifer-Treatment (SAT) system.

    NASA Astrophysics Data System (ADS)

    Papadopoulos, Alexandros; Kallioras, Andreas; Kofakis, Petros; Bumberger, Jan; Schmidt, Felix; Athanasiou, Georgios; Uzunoglou, Nikolaos; Amditis, Angelos; Dietrich, Peter

    2016-04-01

    Artificial recharge of groundwater has an important role to play in water reuse as treated wastewater effluent can be infiltrated into the ground for aquifer recharge. As the effluent moves through the soil and the aquifer, it undergoes significant quality improvements through physical, chemical, and biological processes in the underground environment. Collectively, these processes and the water quality improvement obtained are called soil-aquifer-treatment (SAT) or geopurification. The pilot site of Lavrion Technological & Cultural Park (LTCP) of the National Technical University of Athens (NTUA), involves the employment of plot infiltration basins at experimental scale, which will be using waters of impaired quality as a recharge source, and hence acting as a Soil-Aquifer-Treatment, SAT, system. Τhe LTCP site will be employed as a pilot SAT system complemented by new technological developments, which will be providing continuous monitoring of the quantitative and qualitative characteristics of infiltrating groundwater through all hydrologic zones (i.e. surface, unsaturated and saturated zone). This will be achieved by the development and installation of an integrated system of prototype sensing technologies, installed on-site, and offering a continuous evaluation of the performance of the SAT system. An integrated approach of the performance evaluation of any operating SAT system should aim at parallel monitoring of all hydrologic zones, proving the sustainability of all involved water quality treatment processes within unsaturated and saturated zone. Hence a prototype system of Time and Frequency Domain Reflectometry (TDR & FDR) sensors is developed and will be installed, in order to achieve continuous quantitative monitoring of the unsaturated zone through the entire soil column down to significant depths below the SAT basin. Additionally, the system contains two different radar-based sensing systems that will be offering (i) identification of preferential

  17. The quality of our Nation's waters: water quality in the Mississippi embayment-Texas coastal uplands aquifer system and Mississippi River Valley alluvial aquifer, south-central United States, 1994-2008

    USGS Publications Warehouse

    Kingsbury, James A.; Barlow, Jeannie R.; Katz, Brian G.; Welch, Heather L.; Tollett, Roland W.; Fahlquist, Lynne S.

    2015-01-01

    About 8 million people rely on groundwater from the Mississippi embayment—Texas coastal uplands aquifer system for drinking water. The Mississippi River Valley alluvial aquifer also provides drinking water for domestic use in rural areas but is of primary importance to the region as a source of water for irrigation. Irrigation withdrawals from this aquifer are among the largest in the Nation and play a key role in the economy of the area, where annual crop sales total more than $7 billion. The reliance of the region on both aquifers for drinking water and irrigation highlights the importance of long-term management to sustain the availability and quality of these resources.

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

    USGS Publications Warehouse

    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.

  19. Groundwater withdrawal rates from the Ozark Plateaus aquifer system, 1900 to 2010

    USGS Publications Warehouse

    Knierim, Katherine J.; Nottmeier, Anna M.; Worland, Scott C.; Westerman, Drew A.; Clark, Brian R.

    2016-01-01

    Groundwater is an often overlooked freshwater resource compared to surface water, but groundwater is used widely across the United States, especially during periods of drought. If groundwater models can successfully simulate past conditions, they may be used to evaluate potential future pumping scenarios or climate conditions, thus providing a valuable planning tool for water-resource managers. Quantifying the groundwater-use component for a groundwater model is a vital but often challenging endeavor. This dataset includes groundwater withdrawal rates modeled for the Ozark Plateaus aquifer system (Ozark system) from 1900 to 2010 by groundwater model cell (2.6 square kilometers) for five water-use divisions—agriculture (including irrigation and aquaculture), livestock, public supply (including municipal and rural water districts), and non-agriculture (including thermoelectric power generation, mining, commercial, and industrial)—and by country for domestic (self-supplied) use. Two child items are included with the dataset: “Domestic groundwater withdrawal rates from the Ozark Plateaus aquifer system, 1900 to 2010” and “Public supply, non-agriculture, livestock, and agriculture groundwater withdrawal rates from the Ozark Plateaus aquifer system, 1900 to 2010”. The Ozark system is located in the central United States and is composed of interbedded Cambrian to Pennsylvanian clastic and carbonate lithologies. In stratigraphic order, the Ozark system includes the Basement confining unit, St. Francois aquifer, St. Francois confining unit, Ozark aquifer, Ozark confining unit, Springfield Plateau aquifer, and Western Interior Plains confining system. Generally, the lower portion of the Ozark aquifer is the primary source of groundwater across much of Missouri and the Springfield Plateau aquifer is used across northern Arkansas. A full description of the methods used to model groundwater withdrawal rates from the Ozark system are available in Knierim et al., IN

  20. A semi-analytical model for predicting water quality from an aquifer storage and recovery system

    NASA Astrophysics Data System (ADS)

    Sedighi, Ali; Klammler, Harald; Brown, Chris; Hatfield, Kirk

    2006-10-01

    SummaryAquifer storage and recovery (ASR) involves the injection of freshwater in an aquifer through wells for the purpose of creating a subsurface water supply that is recovered at a later time, often using the same wells, to meet seasonal, long-term, emergency, or other demands. In this paper a numerically efficient semi-analytical model is developed for predicting the quality of water recovered by an ASR system given data on the qualities of ambient and injected waters, hydraulic properties of the aquifer, ambient hydraulic gradient, and system operations. It is assumed the ASR well is installed in a stratified aquifer such that the semi-analytical ASR model (SASRM) simulates the fate of water injected under steady-state conditions into each stratum. It is also assumed that a sharp and mobile interface separates injected water from ambient groundwater such that in situ mixing of water within and between strata does not occur. SASRM assigns particles to define the location the interface in all strata and then follows the migration of these particles under ambient and induced flow conditions. During water recovery, the transient location of the interface is simulated in each stratum and this information is used to quantify the fractions of ambient and injected water extracted at the well-head and the quality of water recovered. To mimic the effects of dispersion, a Latin Hypercube sampling strategy is used to assign hydraulic conductivities according to a predefined probability distribution to the layers of a conceptually stratified aquifer. The volumetric fraction of water received or delivered from any given lithologic unit is assumed proportional to the transmissivity of the stratum normalized to the total aquifer transmissivity interrogated by the ASR well. SARSM is numerically verified against MT3DMS and then calibrated and validated using field data from an ASR system located in Boynton Beach, FL. The field demonstration shows SASRM is capable of predicting

  1. Funding California Schools: The Revenue Limit System. Technical Appendices

    ERIC Educational Resources Information Center

    Weston, Margaret

    2010-01-01

    This document presents the technical appendices accompanying the report, "Funding California Schools: The Revenue Limit System." Included are: (1) Revenue Limit Calculation and Decomposition; (2) Data and Methods; and (3) Base Funding Alternative Simulation Results. (Contains 5 tables and 26 footnotes.) [For the main report,…

  2. Identifying functional zones of denitrification in heterogeneous aquifer systems by numerical simulations - a case study

    NASA Astrophysics Data System (ADS)

    Jang, E.; Kalbacher, T.; He, W.; Shao, H.; Schueth, C.; Kolditz, O.

    2014-12-01

    Nitrate contamination in shallow groundwater is still one of the common problems in many countries. Because of its high solubility and anionic nature, nitrate can easily leach through soil and persist in groundwater for decades. High nitrate concentration has been suggested as a major cause of accelerated eutrophication, methemoglobinemia and gastric cancer. There are several factors influencing the fate of nitrate in groundwater system, which is e.g. distribution of N- sources to soil and groundwater, distribution and amount of reactive substances maintaining denitrification, rate of nitrate degradation and its kinetics, and geological characteristics of the aquifer. Nitrate transport and redox transformation processes are closely linked to complex and spatially distributed physical and chemical interaction, therefore it is difficult to predict and quantify in the field and laboratory experiment. Models can play a key role in elucidation of nitrate reduction pathway in groundwater system and in the design and evaluation of field tests to investigate in situ remediation technologies as well. The goal of the current study is to predict groundwater vulnerability to nitrate, to identify functional zones of denitrification in heterogeneous aquifer systems and to describe the uncertainty of the predictions due to scale effects. For this aim, we developed a kinetic model using multi-component mass transport code OpenGeoSys coupling with IPhreeqc module of the geochemical solver PHREEQC. The developed model included sequential aerobic and nitrate-based respiration, multi-Monod kinetics, multi-species biogeochemical reactions, and geological characteristics of the groundwater aquifer. Moreover water-rock interaction such as secondary mineral precipitation was also included in this model. In this presentation, we focused on the general modelling approach and present the simulation results of nitrate transport simulation in a hypothetical aquifer systems based on data from

  3. Hydrogeology and water quality of the shallow aquifer system at the Mainside, Naval Surface Warfare Center, Dahlgren Site, Dahlgren, Virginia

    USGS Publications Warehouse

    Harlow, G.E.; Bell, C.F.

    1996-01-01

    Lithologic and geophysical logs of boreholes at 29 sites show that the hydrogeologic framework of the Mainside of the Naval Surface Warfare Center, Dahlgren Site at Dahlgren, Virginia, consists of un-consolidated sedimentary deposits of gravel, sand, silt, and clay. The upper 220 feet of these sediments are divided into five hydrogeologic units, including the (1) Columbia (water-table) aquifer, (2) upper confining unit, (3) upper confined aquifer, (4) Nanjemoy-Marlboro confining unit, and (5) Aquia aquifer. The Columbia aquifer in the study area is a local system that is not affected by regional pumping. Ground-water recharge occurs at topographic highs in the northern part of the Mainside, and ground-water discharge occurs at topographic lows associated with adjacent surface-water bodies. Regionally, the direction of ground-water flow in the upper confined and Aquia aquifers is toward the southwest and southeast, respectively. A downward hydraulic gradient exists between the aquifers in the shallow system, and stresses on the Aquia aquifer are indicated by heads that range between 2 and 12 feet below sea level. The ratio of median horizontal hydraulic conductivity of the Columbia aquifer to median vertical hydraulic con-ductivity of the upper confining unit, however, is approximately 2,600:1; therefore, under natural- flow conditions, most water in the Columbia aquifer probably discharges to adjacent surface- water bodies. The composition and distribution of major ions vary in the Columbia aquifer. In general, water samples from wells located along the inland perimeter roads of the study area have chloride or a combination of chloride and sulfate as the dominant anions, and water samples from wells located in the interior of the study area have bicarbonate or a combination of bicarbonate and sulfate as the dominant anions. Sodium and calcium were the dominant cations in most samples. Dissolved solids and four inorganic constituents are present in water from the

  4. Conceptual model of the Great Basin carbonate and alluvial aquifer system

    USGS Publications Warehouse

    Heilweil, Victor M.; Brooks, Lynette E.

    2011-01-01

    A conceptual model of the Great Basin carbonate and alluvial aquifer system (GBCAAS) was developed by the U.S. Geological Survey (USGS) for a regional assessment of groundwater availability as part of a national water census. The study area is an expansion of a previous USGS Regional Aquifer Systems Analysis (RASA) study conducted during the 1980s and 1990s of the carbonate-rock province of the Great Basin. The geographic extent of the study area is 110,000 mi2, predominantly in eastern Nevada and western Utah, and includes 165 hydrographic areas (HAs) and 17 regional groundwater flow systems.A three-dimensional hydrogeologic framework was constructed that defines the physical geometry and rock types through which groundwater moves. The diverse sedimentary units of the GBCAAS study area are grouped into hydrogeologic units (HGUs) that are inferred to have reasonably distinct hydrologic properties due to their physical characteristics. These HGUs are commonly disrupted by large-magnitude offset thrust, strike-slip, and normal faults, and locally affected by caldera formation. The most permeable aquifer materials within the study area include Cenozoic unconsolidated sediments and volcanic rocks, along with Mesozoic and Paleozoic carbonate rocks. The framework was built by extracting and combining information from digital elevation models, geologic maps, cross sections, drill hole logs, existing hydrogeologic frameworks, and geophysical data.

  5. Numerical analysis of the hydrogeologic controls in a layered coastal aquifer system, Oahu, Hawaii, USA

    USGS Publications Warehouse

    Oki, D.S.; Souza, W.R.; Bolke, E.L.; Bauer, G.R.

    1998-01-01

    The coastal aquifer system of southern Oahu, Hawaii, USA, consists of highly permeable volcanic aquifers overlain by weathered volcanic rocks and interbedded marine and terrestrial sediments of both high and low permeability. The weathered volcanic rocks and sediments are collectively known as caprock, because they impede the free discharge of groundwater from the underlying volcanic aquifers. A cross-sectional groundwater flow and transport model was used to evaluate the hydrogeologic controls on the regional flow system in southwestern Oahu. Controls considered were: (a) overall caprock hydraulic conductivity; and (b) stratigraphic variations of hydraulic conductivity in the caprock. Within the caprock, variations in hydraulic conductivity, caused by stratigraphy or discontinuities of the stratigraphic units, are a major control on the direction of groundwater flow and the distribution of water levels and salinity. Results of cross-sectional modeling confirm the general groundwater flow pattern that would be expected in a layered coastal system. Ground-water flow is: (a) predominantly upward in the low-permeability sedimentary units; and (b) predominantly horizontal in the high-permeability sedimentary units.

  6. Triennial changes in groundwater quality in aquifers used for public supply in California: Utility as indicators of temporal trends

    USGS Publications Warehouse

    Kent, Robert; Landon, Matthew K.

    2016-01-01

    From 2004 to 2011, the U.S. Geological Survey collected samples from 1686 wells across the State of California as part of the California State Water Resources Control Board’s Groundwater Ambient Monitoring and Assessment (GAMA) Priority Basin Project (PBP). From 2007 to 2013, 224 of these wells were resampled to assess temporal trends in water quality. The samples were analyzed for 216 water-quality constituents, including inorganic and organic compounds as well as isotopic tracers. The resampled wells were grouped into five hydrogeologic zones. A nonparametric hypothesis test was used to test the differences between initial sampling and resampling results to evaluate possible step trends in water-quality, statewide, and within each hydrogeologic zone. The hypothesis tests were performed on the 79 constituents that were detected in more than 5 % of the samples collected during either sampling period in at least one hydrogeologic zone. Step trends were detected for 17 constituents. Increasing trends were detected for alkalinity, aluminum, beryllium, boron, lithium, orthophosphate, perchlorate, sodium, and specific conductance. Decreasing trends were detected for atrazine, cobalt, dissolved oxygen, lead, nickel, pH, simazine, and tritium. Tritium was expected to decrease due to decreasing values in precipitation, and the detection of decreases indicates that the method is capable of resolving temporal trends.

  7. Triennial changes in groundwater quality in aquifers used for public supply in California: utility as indicators of temporal trends.

    PubMed

    Kent, Robert; Landon, Matthew K

    2016-11-01

    From 2004 to 2011, the U.S. Geological Survey collected samples from 1686 wells across the State of California as part of the California State Water Resources Control Board's Groundwater Ambient Monitoring and Assessment (GAMA) Priority Basin Project (PBP). From 2007 to 2013, 224 of these wells were resampled to assess temporal trends in water quality. The samples were analyzed for 216 water-quality constituents, including inorganic and organic compounds as well as isotopic tracers. The resampled wells were grouped into five hydrogeologic zones. A nonparametric hypothesis test was used to test the differences between initial sampling and resampling results to evaluate possible step trends in water-quality, statewide, and within each hydrogeologic zone. The hypothesis tests were performed on the 79 constituents that were detected in more than 5 % of the samples collected during either sampling period in at least one hydrogeologic zone. Step trends were detected for 17 constituents. Increasing trends were detected for alkalinity, aluminum, beryllium, boron, lithium, orthophosphate, perchlorate, sodium, and specific conductance. Decreasing trends were detected for atrazine, cobalt, dissolved oxygen, lead, nickel, pH, simazine, and tritium. Tritium was expected to decrease due to decreasing values in precipitation, and the detection of decreases indicates that the method is capable of resolving temporal trends.

  8. Incentive Pass-through for Residential Solar Systems in California

    SciTech Connect

    Dong, C. G.; Wiser, Ryan; Rai, Varun

    2014-10-01

    The deployment of solar photovoltaic (PV) systems has grown rapidly over the last decade, partly because of various government incentives. In the United States, among the largest and longest-running incentives have been those established in California. Building on past research, this report addresses the still-unanswered question: to what degree have the direct PV incentives in California been passed through from installers to consumers? This report helps address this question by carefully examining the residential PV market in California (excluding a certain class of third-party-owned PV systems) and applying both a structural-modeling approach and a reduced-form regression analysis to estimate the incentive pass-through rate. The results suggest an average pass-through rate of direct incentives of nearly 100%, though with regional differences among California counties. While these results could have multiple explanations, they suggest a relatively competitive market and well-functioning subsidy program. Further analysis is required to determine whether similar results broadly apply to other states, to other customer segments, to all third-party-owned PV systems, or to all forms of financial incentives for solar (considering not only direct state subsidies, but also utility electric bill savings and federal tax incentives).

  9. Simulation of groundwater flow in the shallow aquifer system of the Delmarva Peninsula, Maryland and Delaware

    USGS Publications Warehouse

    Sanford, Ward E.; Pope, Jason P.; Selnick, David L.; Stumvoll, Ryan F.

    2012-01-01

    Estimating future loadings of nitrogen to the Chesapeake Bay requires knowledge about the groundwater flow system and the traveltime of water and chemicals between recharge at the water table and the discharge to streams and directly to the bay. The Delmarva Peninsula has a relatively large proportion of its land devoted to agriculture and a large associated nitrogen load in groundwater that has the potential to enter the bay in discharging groundwater. To better understand the shallow aquifer system with respect to this loading and the traveltime to the bay, the U.S. Geological Survey constructed a steady-state groundwater flow model for the region. The model is based on estimates of recharge calculated using recently developed regression equations for evapotranspiration and surface runoff. The hydrogeologic framework incorporated into the model includes unconfined surficial aquifer sediments, as well as subcropping confined aquifers and confining beds down to 300 feet below land surface. The model was calibrated using 48 water-level measurements and 24 tracer-based ages from wells located across the peninsula. The resulting steady-state flow solution was used to estimate ages of water in the shallow aquifer system through the peninsula and the distribution and magnitude of groundwater traveltime from recharge at the water table to discharge in surface-water bodies (referred to as return time). Return times vary but are typically less than 10 years near local streams and greater than 100 years near the stream divides. The model can be used to calculate nitrate transport parameters in various local watersheds and predict future trends in nitrate loadings to Chesapeake Bay for different future nitrogen application scenarios.

  10. Aquifer and Shallow San Andreas Fault Permeabilities Inferred from Poroelastic Modeling of InSAR Measurements of Land Surface Deformation in Coachella Valley, California. Ravi Appana and Martin O. Saar

    NASA Astrophysics Data System (ADS)

    Appana, R.; Saar, M. O.

    2009-12-01

    Coachella Valley, in southern California, is located in a region where the southern San Andreas Fault system, comprising three main faults, cuts through the valley aquifer dividing it into many sub-basins. Satellite interferometry (InSAR) has revealed differential uplift of the land surface across the Banning Strand - San Andreas Fault (BSF) and the Garnet Hill Fault (GHF) in the upper Coachella Valley. This uplift is suggested to be caused by the elastic response of the aquifer to artificial groundwater recharge and the tectonic stresses acting in this region. However, the differential uplift appears to be mainly caused by the semi-permeable faults which partially restrict pore-fluid pressure diffusion and related groundwater flow. Hence, by employing numerical models of coupled groundwater flow and poroelastic deformation of the aquifer sediments, the land surface uplift can be utilized to constrain a large-scale hydrologic model of the region that includes hydraulic representations of the faults and the sub-basins. Such a regional model can aide in developing better groundwater management strategies that aim at uniform restorations of ground surface elevations and groundwater table levels and would better constrain fault permeabilities with implications for research related to earthquake dynamics and estimates of potential slip along segments of the southern San Andreas Fault system. Studies have suggested that these segments have reached the end of the inter-seismic strain accumulation period posing the biggest risk to seismic hazards in California. InSAR data showing regional land surface uplift and well data of water table elevations, collected in this region, are used to constrain the model yielding hydraulic parameters. Specifically, our results suggest that the horizontal permeability, kxWWB, of the White Water sub-basin (WWB) and its permeability anisotropy, aWWB = (kz/kx)WWB, are on the order of 0.20x10-11 m2 ≤ kxWWB ≤ 1.2x10-11 m2 and 0.04 ≤ a

  11. 3D geological modeling of the Kasserine Aquifer System, Central Tunisia: New insights into aquifer-geometry and interconnections for a better assessment of groundwater resources

    NASA Astrophysics Data System (ADS)

    Hassen, Imen; Gibson, Helen; Hamzaoui-Azaza, Fadoua; Negro, François; Rachid, Khanfir; Bouhlila, Rachida

    2016-08-01

    The challenge of this study was to create a 3D geological and structural model of the Kasserine Aquifer System (KAS) in central Tunisia and its natural extension into north-east Algeria. This was achieved using an implicit 3D method, which honors prior geological data for both formation boundaries and faults. A current model is presented which provides defendable predictions for the spatial distribution of geology and water resources in aquifers throughout the model-domain. This work has allowed validation of regional scale geology and fault networks in the KAS, and has facilitated the first-ever estimations of groundwater resources in this region by a 3D method. The model enables a preliminary assessment of the hydraulic significance of the major faults by evaluating their influence and role on groundwater flow within and between four compartments of the multi-layered, KAS hydrogeological system. Thus a representative hydrogeological model of the study area is constructed. The possible dual nature of faults in the KAS is discussed in the context that some faults appear to be acting both as barriers to horizontal groundwater flow, and simultaneously as conduits for vertical flow. Also discussed is the possibility that two flow directions occur within the KAS, at a small syncline area of near Feriana. In summary, this work evaluates the influence of aquifer connectivity and the role of faults and geology in groundwater flow within the KAS aquifer system. The current KAS geological model can now be used to guide groundwater managers on the best placement for drilling to test and further refine the understanding of the groundwater system, including the faults connectivity. As more geological data become available, the current model can be easily edited and re-computed to provide an updated model ready for the next stage of investigation by numerical flow modeling.

  12. Assessment of hydrochemical processes and groundwater hydrodynamics in a multilayer aquifer system under long-term irrigation condition: A case study of Nefzaoua basin, southern Tunisia.

    PubMed

    Tarki, M; Ben Hammadi, M; El Mejri, H; Dassi, L

    2016-04-01

    The hydrochemical and isotopic investigation of the Nefzaoua aquifer system demonstrates that groundwater mineralization in is controlled by natural and anthropogenic processes including water-rock interaction and irrigation return flow. It identifies all of the water bodies that flow within the aquifer system and their circulation patterns. The isotopically depleted paleowaters, identified within the deep and intermediate aquifers, undergo significant enrichment by evaporation during irrigation and recharged the shallow aquifer by return flow. Subsequently, they infiltrate to the intermediate aquifer which receives also rainfall modern recharge.

  13. Lead and cadmium associated with saltwater intrusion in a New Jersey aquifer system

    USGS Publications Warehouse

    Pucci, Amleto A.; Harriman, Douglas A.; Ervin, Elisabeth M.; Bratton, Lisa; Gordon, Alison

    1989-01-01

    The U.S. Geological Survey collected ground-water samples from the upper and middle aquifers of the Potomac-Raritan-Magothy aquifer system in a 400-square-mile area of New Jersey from 1984 through 1986. Concentrations of lead were greater than the U.S. Environmental Protection Agency maximum contaminant level (MCL) of 50 micrograms per liter in water from 16 to 239 wells. The concentrations of cadmium were greater than the MCL of 10 micrograms per liter in water from 10 to 241 wells. One-half of the wells that exceeded the lead MCL were in known areas of saltwater intrusion, as were all 10 wells that exceeded the cadmium MCL. The association of elevated concentrations of these metals with elevated concentrations of chloride indicates a mechanism related to saltwater intrusion.

  14. Lead and cadmium associated with saltwater intrusion in a New Jersey aquifer system

    SciTech Connect

    Pucci, A.A. Jr.; Gordon, A. ); Harriman, D.A. ); Ervin, E.M. ); Bratton, L. )

    1989-12-01

    The US Geological Survey collected ground-water samples from the upper and middle aquifers of the Potomac-Raritan-Magothy aquifer system in a 400-square-mile are of New Jersey from 1984 through 1986. Concentrations of lead were greater than the US Environmental Protection Agency maximum contaminant level (MCL) of 50 micrograms per liter in water from 16 to 239 wells. The concentrations of cadmium were greater than the MCL of 10 micrograms per liter in water from 10 to 241 wells. One-half of the wells that exceeded the lead MCL were in known areas of saltwater intrusion, as were all 10 wells that exceeded the cadmium MCL. The association of elevated concentrations of these metals with elevated concentrations of chloride indicates a mechanism related to saltwater intrusion.

  15. Geostatistical Simulation of Hydrofacies Heterogeneity of the West Thessaly Aquifer Systems in Greece

    SciTech Connect

    Modis, K. Sideri, D.

    2013-06-15

    Integrating geological properties, such as relative positions and proportions of different hydrofacies, is of highest importance in order to render realistic geological patterns. Sequential indicator simulation (SIS) and Plurigaussian simulation (PS) are alternative methods for conceptual and deterministic modeling for the characterization of hydrofacies distribution. In this work, we studied the spatial differentiation of hydrofacies in the alluvial aquifer system of West Thessaly basin in Greece. For this, we applied both SIS and PS techniques to an extensive set of borehole data from that basin. Histograms of model versus experimental hydrofacies proportions and indicative cross sections were plotted in order to validate the results. The PS technique was shown to be more effective in reproducing the spatial characteristics of the different hydrofacies and their distribution across the study area. In addition, the permeability differentiations reflected in the PS model are in accordance to known heterogeneities of the aquifer capacity.

  16. Groundwater quality in the Southeastern Coastal Plain aquifer system, southeastern United States

    USGS Publications Warehouse

    Barlow, Jeannie; Lindsey, Bruce; Belitz, Kenneth

    2017-01-19

    Groundwater provides nearly 50 percent of the Nation’s drinking water. To help protect this vital resource, the U.S. Geological Survey (USGS) National Water-Quality Assessment (NAWQA) Project assesses groundwater quality in aquifers that are important sources of drinking water. The Southeastern Coastal Plain aquifer system constitutes one of the important areas being evaluated. One or more inorganic constituents with human-health benchmarks were detected at high concentrations in about 6 percent of the study area and at moderate concentrations in about 13 percent. One or more organic constituents with human-health benchmarks were detected at moderate concentrations in about 3 percent of the study area.

  17. Groundwater quality in the Coastal Lowlands aquifer system, south-central United States

    USGS Publications Warehouse

    Barlow, Jeannie R.B.; Belitz, Kenneth

    2017-01-19

    Groundwater provides nearly 50 percent of the Nation’s drinking water. To help protect this vital resource, the U.S. Geological Survey (USGS) National Water-Quality Assessment (NAWQA) Project assesses groundwater quality in aquifers that are important sources of drinking water. The Coastal Lowlands aquifer system constitutes one of the important areas being evaluated. One or more inorganic constituents with human-health benchmarks were detected at high concentrations in about 12 percent of the study area and at moderate concentrations in about 18 percent. Organic constituents were not detected at high or moderate concentrations in the study area.

  18. Hydrogeology and Potentiometric Surface of the Dublin and Midville Aquifer Systems in Richmond County, Georgia, January 2007

    USGS Publications Warehouse

    Williams, Lester J.

    2007-01-01

    INTRODUCTION The Dublin and Midville aquifer systems are part of the Cretaceous aquifer system that underlies most of Richmond County, Georgia (Gorday, 1985; Falls and others, 1997). The Cretaceous aquifer system is the second most productive aquifer in Georgia and is a major source of water in the region. About 220 million gallons per day (Mgal/d) of water was withdrawn from the Cretaceous aquifer system during 2000 in Georgia (Fanning, 2003). The Augusta-Richmond County Water System is the largest public water supplier in the county and withdrew 13 Mgal/d of ground water during 2000; withdrawals decreased from 2001 to 2005. The towns of Hephzibah and Blythe withdrew 0.4 and 0.03 Mgal/d, respectively. Industrial ground-water withdrawals are concentrated along the Savannah River and totaled 2.89 Mgal/d. To monitor seasonal and long-term water-level fluctuations and trends in the aquifers, the U.S. Geological Survey (USGS) - in cooperation with Augusta Utilities - maintains a countywide network of about 100 water-level monitoring wells in various aquifers, including a new continuous monitoring site (well 30AA33) and two existing USGS-Georgia Environmental Protection Division network sites (wells 29AA09 and 30AA04). Data compiled during this study were used to better define the hydrogeologic units and to construct an updated potentiometric-surface map for the area, which is used to better understand ground-water movement in the Cretaceous aquifer system. In addition, the potentiometric surface and related water-level data can be used for water-resource planning and to update ground-water flow models for the region (Clarke and West, 1997; Cherry, 2006).

  19. Hydrology of the Tertiary-Cretaceous aquifer system in the vicinity of Fort Rucker Aviation Center, Alabama

    USGS Publications Warehouse

    Scott, J.C.; Law, L.R.; Cobb, Riley

    1984-01-01

    Fort Rucker Aviation Center, built in 1941-42, uses ground water for its water supply. The demand for water began to exceed the capacity of the well field in 1976. The Tertiary-Cretaceous aquifer system in the Fort Rucker area consists of an upper and lower aquifer. The upper aquifer consists of the basal part of the Tuscahoma Sand, the Nanafalia and Clayton Formations, and the upper part of the Providence Sand. The lower aquifer consists of the lower part of the Providence Sand and the Ripley Formation. Most large capacity (greater than 100 gal/min (gallons per minute)) wells in the Fort Rucker area are developed in one of these aquifers, and produce 500 gal/min or more. An aquifer test made at Fort Rucker during the study indicates that the transmissivity of the upper aquifer is about 7,000 ft sq/d (feet squared per day). This test and a potentiometric map of the area indicate that wells spaced too closely together is a major problem at pumping centers in the study area. (USGS)

  20. Evaluation of the hydrologic system and selected water-management alternatives in the Owens Valley, California

    USGS Publications Warehouse

    Danskin, Wesley R.

    1998-01-01

    The Owens Valley, a long, narrow valley along the east side of the Sierra Nevada in eastcentral California, is the main source of water for the city of Los Angeles. The city diverts most of the surface water in the valley into the Owens River?Los Angeles Aqueduct system, which transports the water more than 200 miles south to areas of distribution and use. Additionally, ground water is pumped or flows from wells to supplement the surface-water diversions to the river? aqueduct system. Pumpage from wells needed to supplement water export has increased since 1970, when a second aqueduct was put into service, and local residents have expressed concerns that the increased pumping may have a detrimental effect on the environment and the native vegetation (indigenous alkaline scrub and meadow plant communities) in the valley. Native vegetation on the valley floor depends on soil moisture derived from precipitation and from the unconfined part of a multilayered ground-water system. This report, which describes the evaluation of the hydrologic system and selected water-management alternatives, is one in a series designed to identify the effects that ground-water pumping has on native vegetation and evaluate alternative strategies to mitigate any adverse effects caused by pumping. The hydrologic system of the Owens Valley can be conceptualized as having three parts: (1) an unsaturated zone affected by precipitation and evapotranspiration; (2) a surface-water system composed of the Owens River, the Los Angeles Aqueduct, tributary streams, canals, ditches, and ponds; and (3) a saturated ground-water system contained in the valley fill. Analysis of the hydrologic system was aided by development of a ground-water flow model of the ?aquifer system,? which is defined as the most active part of the ground-water system and which includes nearly all of the Owens Valley except for the area surrounding the Owens Lake. The model was calibrated and verified for water years 1963?88 and

  1. California air transportation study: A transportation system for the California Corridor of the year 2010

    NASA Technical Reports Server (NTRS)

    1989-01-01

    To define and solve the problems of transportation in the California Corrider in the year 2010, the 1989 California Polytechnic State University Aeronautical Engineering Senior Design class determined future corridor transportation needs and developed a system to meet the requirements. A market study, which included interpreting travel demand and gauging the future of regional and national air travel in and out of the corridor, allowed the goals of the project to be accurately refined. Comprehensive trade-off studies of several proposed transporation systems were conducted to determine which components would form the final proposed system. Preliminary design and further analysis were performed for each resulting component. The proposed system consists of three vehicles and a special hub or mode mixer, the Corridor Access Port (CAP). The vehicles are: (1) an electric powered aircraft to serve secondary airports and the CAP; (2) a high speed magnetic levitation train running through the CAP and the high population density areas of the corridor; and (3) a vertical takeoff and landing tilt rotor aircraft to serve both intercity and intrametropolitan travelers from the CAP and city vertiports. The CAP is a combination and an extension of the hub, mode mixer, and Wayport concepts. The CAP is an integrated part of the system which meets the travel demands in the corridor, and interfaces with interstate and international travel.

  2. Hydrostratigraphy characterization of the Floridan aquifer system using ambient seismic noise

    NASA Astrophysics Data System (ADS)

    James, Stephanie; Screaton, Elizabeth; Russo, Raymond; Panning, Mark; Bremner, Paul; Stanciu, Christian; Torpey, Megan; Hongsresawat, Sutatcha; Farrell, Matthew

    2017-02-01

    We investigated a new technique for aquifer characterization that uses cross-correlation of ambient seismic noise to determine seismic velocity structure of the Floridan aquifer system. Accurate characterization of aquifer systems is vital to hydrogeologic research and groundwater management but is difficult due to limited subsurface data and heterogeneity. Previous research on the carbonate Floridan aquifer system found that confining units and high permeability flow zones have distinct seismic velocities. We deployed an array of 9 short period seismometers from 11/2013 to 3/2014 in Indian Lake State Forest near Ocala, Florida, to image the hydrostratigraphy of the aquifer system using ambient seismic noise. We find that interstation distance strongly influences the upper and lower frequency limits of the dataset. Seismic waves propagating within 1.5 and 7 wavelengths between stations were optimal for reliable group velocity measurements and both an upper and lower wavelength threshold was used. A minimum of 100-250 hours of signal was needed to maximize signal to noise ratio and to allow cross-correlation convergence. We averaged measurements of group velocity between station pairs at each frequency band to create a network average dispersion curve. A family of 1-D shear-wave velocity profiles that best represents the network average dispersion was then generated using a Markov Chain Monte Carlo (MCMC) algorithm. The MCMC algorithm was implemented with either a fixed number of layers, or as transdimensional in which the number of layers was a free parameter. Results from both algorithms require a prominent velocity increase at ∼200 m depth. A shallower velocity increase at ∼60 m depth was also observed, but only in model ensembles created by collecting models with the lowest overall misfit to the observed data. A final round of modeling with additional prior constraints based on initial results and well logs produced a mean shear-wave velocity profile taken

  3. Chemical characteristics of water in the surficial aquifer system, Dade County, Florida

    USGS Publications Warehouse

    Sonntag, W.H.

    1987-01-01

    Geohydrologic test drilling was conducted throughout Dade County to describe the chemical characteristics of water from geohydrologic units in the surficial aquifer system. Water quality analysis of samples collected from the test wells completed in central Dade County indicates that the Biscayne aquifer (unit A), the upper clastic unit of the Tamiami Formation (unit B), and parts of a limestone, sandstone, and sand unit of the Tamiami Formation (unit C) have been effectively flushed of residual seawater, and contain primarily calcium bicarbonate groundwater. The lower parts of unit C and the lower clastic unit of the Tamiami Formation (unit D) primarily contain calcium-sodium bicarbonate or sodium bicarbonate type water. An analysis of variance test indicates that water in units A and B is not significantly (0.05 probability level) different in composition. Mean concentrations of dissolved solids, sodium, and chloride are significantly different between units A and C, whereas mean concentrations of dissolved solids, calcium, sodium, and chloride are significantly different between units A and D. Groundwater in the surficial aquifer system in northwestern Dade County is more mineralized than groundwater that occurs elsewhere in the county (except in coastal areas affected by saltwater). An analysis of variance test indicates that mean concentrations of dissolved solids, sodium, and chloride at sites in northwestern Dade County, developed in units A and C, are significantly different from the mean concentrations of these constituents at sites throughout the rest of the county. Water in this part of the surficial aquifer system is similar to highly mineralized water found in western Broward County. However, in northwestern Dade County, the groundwater has been diluted to a greater extent by less mineralized recharge water. Overall, groundwater in the four major geohydrologic units of the surficial aquifer system of Dade County is suitable for most uses. Maximum

  4. Soil aquifer treatment (SAT) system: a case study.

    PubMed

    Kaur, Samanpreet; Singh, Mandeep

    2002-07-01

    Water scarcity is the major issue in all parts of world. Wastewater reuse is one alternative. SAT proves to efficient, economical and feasible method for wastewater treatment. SAT system achieves an excellent reduction of biochemical oxygen demand, suspended solids, and fecal coliform. About 90% of water applied to SAT site is returned to watershed. A case study has been made by the authors to increase the efficiency of this system.

  5. Post audit of a numerical prediction of wellfield drawdown in a semiconfined aquifer system

    USGS Publications Warehouse

    Stewart, M.; Langevin, C.

    1999-01-01

    A numerical ground water flow model was created in 1978 and revised in 1981 to predict the drawdown effects of a proposed municipal wellfield permitted to withdraw 30 million gallons per day (mgd; 1.1 x 105 m3/day) of water from the semiconfined Floridan Aquifer system. The predictions are based on the assumption that water levels in the semiconfined Floridan Aquifer reach a long-term, steady-state condition within a few days of initiation of pumping. Using this assumption, a 75 day simulation without water table recharge, pumping at the maximum permitted rates, was considered to represent a worst-case condition and the greatest drawdowns that could be experienced during wellfield operation. This method of predicting wellfield effects was accepted by the permitting agency. For this post audit, observed drawdowns were derived by taking the difference between pre-pumping and post-pumping potentiometric surface levels. Comparison of predicted and observed drawdowns suggests that actual drawdown over a 12 year period exceeds predicted drawdown by a factor of two or more. Analysis of the source of error in the 1981 predictions suggests that the values used for transmissivity, storativity, specific yield, and leakance are reasonable at the wellfield scale. Simulation using actual 1980-1992 pumping rates improves the agreement between predicted and observed drawdowns. The principal source of error is the assumption that water levels in a semiconfined aquifer achieve a steady-state condition after a few days or weeks of pumping. Simulations using a version of the 1981 model modified to include recharge and evapotranspiration suggest that it can take hundreds of days or several years for water levels in the linked Surficial and Floridan Aquifers to reach an apparent steady-state condition, and that slow declines in levels continue for years after the initiation of pumping. While the 1981 'impact' model can be used for reasonably predicting short-term, wellfield

  6. Geohydrology and simulation of steady-state flow conditions in regional aquifer systems in Cretaceous and older rocks underlying Kansas, Nebraska, and parts of Arkansas, Colorado, Missouri, New Mexico, Oklahoma, South Dakota, Texas, and Wyoming

    USGS Publications Warehouse

    Signor, D.C.; Helgesen, J.O.; Jorgensen, D.G.; Leonard, R.B.

    1997-01-01

    Three regional aquifers systems are the basis for describing the geohydrology of bedrock aquifers in the central United States. The Great Plains aquifer system, composed of Lower Cretaceous sandstone, generally contains brackish water (1,000 to 10,000 milligrams per liter dissolved solids); the Western Interior Plains aquifer system of lower Paleozoic rocks contains saline water and is laterally adjacent to the freshwater-bearing Ozark Plateaus aquifer system composed of rocks of the same age.

  7. Groundwater Flow Model of Göksu Delta Coastal Aquifer System

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

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

  8. Description of data files compiled for the Central Midwest Regional Aquifer-System Analysis

    USGS Publications Warehouse

    Helgesen, John O.; Hansen, Cristi V.

    1989-01-01

    Several types of geologic and hydrologic data were collected and compiled as part of the Central Midwest Regional Aquifer-System Analysis. The study described the hydrology of Cambrian-age through Cretaceous-age rocks in all of Kansas and Nebraska and parts of eight other states. Information from both water wells and petroleum wells was obtained from numerous State, Federal, and private sources. The completeness, quality, and distribution of the data varies considerably. Most data files contain data selected to represent the regional scope of the study. The log data file contains about 850 lithologic logs and about 750 geophysical logs. The hydraulic-head data file contains about 1 ,400 measured water levels and about 2,600 values of equivalent freshwater head derived from drill-stem-test analyses. The hydrochemical data file contains about 2,900 water quality analyses. The aquifer-property data file contains about 1,050 values. In addition to site-specific data, areal information in the form of model-data arrays is available for initial hydraulic head, transmissivity, and vertical leakance. These data describe the major geohydrologic units studied in terms of a three-dimensional grid, 28 rows x 33 columns x 5 layers. Parts of the hydraulic-head, hydrochemical, and aquifer-property data files are proprietary. The fluid-withdrawal data file was developed for study use only. Most other data described herein are available on magnetic tape from the U.S. Geological Survey in Lawrence, Kansas. (USGS)

  9. Calibrated models as management tools for stream-aquifer systems: the case of central Kansas, USA

    USGS Publications Warehouse

    Sophocleous, M.; Perkins, S.P.

    1993-01-01

    We address the problem of declining streamflows in interconnected stream-aquifer systems and explore possible management options to address the problem for two areas of central Kansas: the Arkansas River valley from Kinsley to Great Bend and the lower Rattlesnake Creek-Quivira National Wildlife Refuge area. The approach we followed implements, calibrates, and partially validates for the study areas a stream-aquifer numerical model combined with a parameter estimation package and sensitivity analysis. Hydrologic budgets for both predevelopment and developed conditions indicate significant differences in the hydrologic components of the study areas resulting from development. The predevelopment water budgets give an estimate of natural ground-water recharge, whereas the budgets for developed conditions give an estimate of induced recharge, indicating that major ground-water development changes the recharge-discharge regime of the model areas with time. Such stream-aquifer models serve to link proposed actions to hydrologic effects, as is clearly demonstrated by the effects of various management alternatives on the streamflows of the Arkansas River and Rattlesnake Creek. Thus we show that a possible means of restoring specified streamflows in the area is to implement protective stream corridors with restricted ground-water extraction. ?? 1993.

  10. Calibrated models as management tools for stream-aquifer systems: the case of central Kansas, USA

    NASA Astrophysics Data System (ADS)

    Sophocleous, Marios; Perkins, Samuel P.

    1993-12-01

    We address the problem of declining streamflows in interconnected stream-aquifer systems and explore possible management options to address the problem for two areas of central Kansas: the Arkansas River valley from Kinsley to Great Bend and the lower Rattlesnake Creek-Quivira National Wildlife Refuge area. The approach we followed implements, calibrates, and partially validates for the study areas a stream-aquifer numerical model combined with a parameter estimation package and sensitivity analysis. Hydrologic budgets for both predevelopment and developed conditions indicate significant differences in the hydrologic components of the study areas resulting from development. The predevelopment water budgets give an estimate of natural ground-water recharge, whereas the budgets for developed conditions give an estimate of induced recharge, indicating that major ground-water development changes the recharge-discharge regime of the model areas with time. Such stream-aquifer models serve to link proposed actions to hydrologic effects, as is clearly demonstrated by the effects of various management alternatives on the streamflows of the Arkansas River and Rattlesnake Creek. Thus we show that a possible means of restoring specified streamflows in the area is to implement protective stream corridors with restricted ground-water extraction.

  11. Flow and Transport in the Hanford 300 Area Vadose Zone-Aquifer-River System

    SciTech Connect

    Waichler, Scott R.; Yabusaki, Steven B.

    2005-07-13

    Contaminant migration in the 300 Area unconfined aquifer is strongly coupled to fluctuations in the Columbia River stage. To better understand the interaction between the river, aquifer, and vadose zone, a 2-D saturated-unsaturated flow and transport model was developed for a vertical cross-section aligned west-east across the Hanford Site 300 Area, nearly perpendicular to the river. The model was used to investigate water flow and tracer transport in the vadose zone-aquifer-river flow system, in support of the ongoing study of the 300 Area uranium plume. The STOMP simulator was used to model 1-year from 3/1/92 to 2/28/93, a period when hourly data were available for both groundwater and river levels. Net water flow to the river (per 1-meter width of shoreline) was 182 m3/y in the base case, but the cumulative exchange or total flow back and forth across the riverbed was 30 times greater. The low river case had approximately double the net water and Groundwater tracer flux into the river as compared to the base case.

  12. Organic molecules as sorbing tracers for the assessment of surface areas in consolidated aquifer systems

    NASA Astrophysics Data System (ADS)

    Schaffer, Mario; Warner, Wiebke; Kutzner, Susann; Börnick, Hilmar; Worch, Eckhard; Licha, Tobias

    2017-03-01

    Based on the assumption that the specific surface area to volume ratio Asurf/V of consolidated rock materials is proportional to the surface area available for sorption, several inorganic cations were recently proposed as sorbing (cation exchanging) tracers for estimating these ratios in aquifers (e.g., for deriving the efficient heat exchange area of geothermal reservoirs). The main disadvantages of inorganic ions, however, are the limited number of suitable ions, their potential geogenic background, and their challenging online detection at trace concentrations. In this work, the spectrum of chemical substances used as sorbing tracers expands by considering fluorescent organic compounds that are cationic. They have the advantage of being highly water soluble and easy to measure online at very low concentrations. Results from systematic lab column experiments with seven selected organic cations under various conditions (different salinities and temperatures) are presented, emphasizing the potential of organic molecules as alternative sorbing tracers especially in consolidated aquifer systems. This work is a first stepping stone in identifying suitable molecular structures that can be selected or even individually adapted to the requirements of the tracer tests and prevailing aquifer conditions.

  13. Saltwater intrusion in the Floridan aquifer system near downtown Brunswick, Georgia, 1957–2015

    USGS Publications Warehouse

    Cherry, Gregory S.; Peck, Michael

    2017-02-16

    IntroductionThe Floridan aquifer system (FAS) consists of the Upper Floridan aquifer (UFA), an intervening confining unit of highly variable properties, and the Lower Floridan aquifer (LFA). The UFA and LFA are primarily composed of Paleocene- to Oligocene-age carbonate rocks that include, locally, Upper Cretaceous rocks. The FAS extends from coastal areas in southeastern South Carolina and continues southward and westward across the coastal plain of Georgia and Alabama, and underlies all of Florida. The thickness of the FAS varies from less than 100 feet (ft) in aquifer outcrop areas of South Carolina to about 1,700 ft near the city of Brunswick, Georgia.Locally, in southeastern Georgia and the Brunswick– Glynn County area, the UFA consists of an upper water-bearing zone (UWBZ) and a lower water-bearing zone (LWBZ), as identified by Wait and Gregg (1973), with aquifer test data indicating the upper zone has higher productivity than the lower zone. Near the city of Brunswick, the LFA is composed of two permeable zones: an early middle Eocene-age upper permeable zone (UPZ) and a highly permeable lower zone of limestone (LPZ) of Paleocene and Late Cretaceous age that includes a deeply buried, cavernous, saline water-bearing unit known as the Fernandina permeable zone. Maslia and Prowell (1990) inferred the presence of major northeast–southwest trending faults through the downtown Brunswick area based on structural analysis of geophysical data, northeastward elongation of the potentiometric surface of the UFA, and breaches in the local confining unit that influence the area of chloride contamination. Pronounced horizontal and vertical hydraulic head gradients, caused by pumping in the UFA, allow saline water from the FPZ to migrate upward into the UFA through this system of faults and conduits.Saltwater was first detected in the FAS in wells completed in the UFA near the southern part of the city of Brunswick in late 1957. By the 1970s, a plume of groundwater

  14. Hydrogeologic framework of the Wood River Valley aquifer system, south-central Idaho

    USGS Publications Warehouse

    Bartolino, James R.; Adkins, Candice B.

    2012-01-01

    The Wood River Valley contains most of the population of Blaine County and the cities of Sun Valley, Ketchum, Hailey, and Bellevue. This mountain valley is underlain by the alluvial Wood River Valley aquifer system, which consists primarily of a single unconfined aquifer that underlies the entire valley, an underlying confined aquifer that is present only in the southernmost valley, and the confining unit that separates them. The entire population of the area depends on groundwater for domestic supply, either from domestic or municipal-supply wells, and rapid population growth since the 1970s has caused concern about the long-term sustainability of the groundwater resource. As part of an ongoing U.S. Geological Survey effort to characterize the groundwater resources of the Wood River Valley, this report describes the hydrogeologic framework of the Wood River Valley aquifer system. Although most of the Wood River Valley aquifer system is composed of Quaternary-age sediments and basalts of the Wood River Valley and its tributaries, older igneous, sedimentary, or metamorphic rocks that underlie these Quaternary deposits also are used for water supply. It is unclear to what extent these rocks are hydraulically connected to the main part of Wood River Valley aquifer system and thus whether they constitute separate aquifers. Paleozoic sedimentary rocks in and near the study area that produce water to wells and springs are the Phi Kappa and Trail Creek Formations (Ordovician and Silurian), the Milligen Formation (Devonian), and the Sun Valley Group including the Wood River Formation (Pennsylvanian-Permian) and the Dollarhide Formation (Permian). These sedimentary rocks are intruded by granitic rocks of the Late Cretaceous Idaho batholith. Eocene Challis Volcanic Group rocks overlie all of the older rocks (except where removed by erosion). Miocene Idavada Volcanics are found in the southern part of the study area. Most of these rocks have been folded, faulted, and

  15. Development of a Control Optimization System for Real Time Monitoring of Managed Aquifer Recharge and Recovery Systems Using Intelligent Sensors

    NASA Astrophysics Data System (ADS)

    Smits, K. M.; Drumheller, Z. W.; Lee, J. H.; Illangasekare, T. H.; Regnery, J.; Kitanidis, P. K.

    2015-12-01

    Aquifers around the world show troubling signs of irreversible depletion and seawater intrusion as climate change, population growth, and urbanization lead to reduced natural recharge rates and overuse. Scientists and engineers have begun to revisit the technology of managed aquifer recharge and recovery (MAR) as a means to increase the reliability of the diminishing and increasingly variable groundwater supply. Unfortunately, MAR systems remain wrought with operational challenges related to the quality and quantity of recharged and recovered water stemming from a lack of data-driven, real-time control. This research seeks to develop and validate a general simulation-based control optimization algorithm that relies on real-time data collected though embedded sensors that can be used to ease the operational challenges of MAR facilities. Experiments to validate the control algorithm were conducted at the laboratory scale in a two-dimensional synthetic aquifer under both homogeneous and heterogeneous packing configurations. The synthetic aquifer used well characterized technical sands and the electrical conductivity signal of an inorganic conservative tracer as a surrogate measure for water quality. The synthetic aquifer was outfitted with an array of sensors and an autonomous pumping system. Experimental results verified the feasibility of the approach and suggested that the system can improve the operation of MAR facilities. The dynamic parameter inversion reduced the average error between the simulated and observed pressures between 12.5 and 71.4%. The control optimization algorithm ran smoothly and generated optimal control decisions. Overall, results suggest that with some improvements to the inversion and interpolation algorithms, which can be further advanced through testing with laboratory experiments using sensors, the concept can successfully improve the operation of MAR facilities.

  16. Application of isotopic tracers as a tool for understanding hydrodynamic behavior of the highly exploited Diass aquifer system (Senegal)

    NASA Astrophysics Data System (ADS)

    Madioune, Diakher Hélène; Faye, Serigne; Orban, Philippe; Brouyère, Serge; Dassargues, Alain; Mudry, Jacques; Stumpp, Christine; Maloszewski, Piotr

    2014-04-01

    The Diass horst aquifer system located 50 km east of Dakar (Senegal) is exploited in two main aquifers covered by a sandy superficial aquifer: the confined/unconfined Palaeocene karstic limestone and the confined Maastrichtian sandstone aquifer underneath. This system has experienced intensive groundwater abstraction during the last 50 years to supply increasing water demand, agricultural and industrial needs. The high abstraction rate from 1989 to 2009 (about 109,000 m3/d) has caused a continuous groundwater level decline (up to 30 m), a modification of the groundwater flow and salinization in parts of the aquifers. The objective of the study is to improve our understanding of the system functioning with regards to high pumping, identify the geochemical reactions that take place in the system, infer origin and timing of recharge by using mainly stable (δ18O, δ2H, 13C) and radioactive (3H and 14C) isotopes. Water types defined in the Piper diagram vary in order of abundance from Ca-HCO3 (65%), Ca/Na-Cl (20%), Na-HCO3 (3%) and Na-Cl (12%). Values of δ18O and δ2H for the superficial aquifer range between -5.8 and -4.2‰ and between -42 and -31‰, respectively. For the Palaeocene aquifer they range from -5.8 to -5.0‰ and from -38 to -31‰, respectively; values in the Maastrichtian aquifer are between -5.9 and -4.3‰ for δ18O and -38 to -26‰ for δ2H. Plotted against the conventional δ18O vs δ2H diagram, data from the upper aquifer exhibit a dispersed distribution with respect to isotopic fractionation while those of the Palaeocene and Maastrichtian aquifers are aligned parallel and slightly below/or on the Global Meteoric Water Line (GMWL) evidencing ancient waters which had evaporated during infiltration. The low tritium (generally <0.7 TU) and 14C (0.7-57.2 pmc) contents indicate predominance of older water being recharged during the Pleistocene and Holocene periods. However, few boreholes which exhibit high tritium (1.2-4.3 TU) and 14C (65.7-70.8 pmc

  17. Delineation of Holocene-Pleistocene aquifer system in parts of Middle Ganga Plain, Bihar, Eastern India through DC resistivity survey

    NASA Astrophysics Data System (ADS)

    Ganguli, Shuva Shankha; Singh, Shashikant

    2016-11-01

    The study area forms a part of the Middle Ganga Plain (MGP) and experiences intensive groundwater draft due to domestic, irrigation and industrial purposes. Geoelectrical surveys were carried out in a geomorphic unit of MGP called South Ganga Plain, along the north-south traverse covering a total 50 km stretch. Interpreted results of the total of 17 vertical electrical soundings, carried out, provided information on aquifer and aquitard geometry and sediment nature in different aquifer systems. Bedrock topography is also demarcated along the north-south transect. The estimated dip of massive bedrock is less than 0.5° and dips toward north. The survey results show that a two-tier aquifer system exists in Newer alluvium parts of the study area and it is replaced by a single aquifer system at Older alluvium that occurs under thick clay/sandy clay bed in the southern part. An exponential decay of the aquifer potential is observed from north to south. Paleo channel Sone River is traced and it forms a potential aquifer.

  18. Application of advanced geophysical logging methods in the characterization of a fractured-sedimentary bedrock aquifer, Ventura County, California

    USGS Publications Warehouse

    Williams, John H.; Lane, Jr., John W.; Singha, Kamini; Haeni, F. Peter

    2002-01-01

    An integrated suite of advanced geophysical logging methods was used to characterize the geology and hydrology of three boreholes completed in fractured-sedimentary bedrock in Ventura County, California. The geophysical methods included caliper, gamma, electromagnetic induction, borehole deviation, optical and acoustic televiewer, borehole radar, fluid resistivity, temperature, and electromagnetic flowmeter. The geophysical logging 1) provided insights useful for the overall geohydrologic characterization of the bedrock and 2) enhanced the value of information collected by other methods from the boreholes including core-sample analysis, multiple-level monitoring, and packer testing.The logged boreholes, which have open intervals of 100 to 200 feet, penetrate a sequence of interbedded sandstone and mudstone with bedding striking 220 to 250 degrees and dipping 15 to 40 degrees to the northwest. Fractures intersected by the boreholes include fractures parallel to bedding and fractures with variable strike that dip moderately to steeply. Two to three flow zones were detected in each borehole. The flow zones consist of bedding-parallel or steeply dipping fractures or a combination of bedding-parallel fractures and moderately to steeply dipping fractures. About 75 to more than 90 percent of the measured flow under pumped conditions was produced by only one of the flow zones in each borehole.

  19. Application of advanced geophysical logging methods in the characterization of a fractured-sedimentary bedrock aquifer, Ventura County, California

    USGS Publications Warehouse

    Williams, John H.; Lane, Jr., John W.; Singha, Kamini; Haeni, F. Peter

    2002-01-01

    An integrated suite of advanced geophysical logging methods was used to characterize the geology and hydrology of three boreholes completed in fractured-sedimentary bedrock in Ventura County, California. The geophysical methods included caliper, gamma, electromagnetic induction, borehole deviation, optical and acoustic televiewer, borehole radar, fluid resistivity, temperature, and electromagnetic flowmeter. The geophysical logging 1) provided insights useful for the overall geohydrologic characterization of the bedrock and 2) enhanced the value of information collected by other methods from the boreholes including core-sample analysis, multiple-level monitoring, and packer testing. The logged boreholes, which have open intervals of 100 to 200 feet, penetrate a sequence of interbedded sandstone and mudstone with bedding striking 220 to 250 degrees and dipping 15 to 40 degrees to the northwest. Fractures intersected by the boreholes include fractures parallel to bedding and fractures with variable strike that dip moderately to steeply. Two to three flow zones were detected in each borehole. The flow zones consist of bedding-parallel or steeply dipping fractures or a combination of bedding-parallel fractures and moderately to steeply dipping fractures. About 75 to more than 90 percent of the measured flow under pumped conditions was produced by only one of the flow zones in each borehole.

  20. Simulation of ground-water flow in the Potomac-Raritan-Magothy aquifer system, Pennsauken Township and vicinity, New Jersey

    USGS Publications Warehouse

    Pope, Daryll A.; Watt, Martha K.

    2004-01-01

    The Potomac-Raritan-Magothy aquifer system is one of the primary sources of potable water in the Coastal Plain of New Jersey, particularly in heavily developed areas along the Delaware River. In Pennsauken Township, Camden County, local drinking-water supplies from this aquifer system have been contaminated by hexavalent chromium at concentrations that exceed the New Jersey maximum contaminant level. In particular, ground water at the Puchack well field has been adversely affected to the point where, since 1984, water is no longer withdrawn from this well field for public supply. The area that contains the Puchack well field was added to the National Priorities List in 1998 as a Superfund site. The U.S. Geological Survey (USGS) conducted a reconnaissance study from 1996 to 1998 during which hydrogeologic and water-quality data were collected and a ground-water-flow model was developed to describe the conditions in the aquifer system in the Pennsauken Township area. The current investigation by the USGS, in cooperation with the U.S. Environmental Protection Agency (USEPA), is an extension of the previous study. Results of the current study can be applied to a Remedial Investigation and Feasibility Study conducted at the Puchack well field Superfund site. The USGS study collected additional data on the hydrogeology and water-quality in the area. These data were incorporated into a refined model of the ground-water-flow system in the Potomac-Raritan-Magothy aquifer system. A finite-difference model was developed to simulate ground-water flow and the advective transport of chromium-contaminated ground water in the aquifers of the Potomac-Raritan-Magothy aquifer system in the Pennsauken Township area. An 11-layer model was used to represent the complex hydrogeologic framework. The model was calibrated using steady-state water-level data from March 1998, April 1998, and April 2001. Water-level recovery during the shutdown of Puchack 1 during March to April 1998 was

  1. Hydrochemical zonation of the western part of Göksu Delta aquifer system, Southern Turkey

    NASA Astrophysics Data System (ADS)

    Dokuz, U. E.; Çelik, M.; Arslan, Ş.; Engin, H.

    2012-04-01

    In general, coastal areas are preferred places for human settlement, especially at places where infrastructure routes benefit from rivers, streets, or harbours. As a result, these areas usually suffer from rising population and endure increasingly high demand on natural resources like water. Göksu Delta, located in southern Turkey, is one of the important wetland areas of Turkey at the Mediterranean coast. It is divided into two parts by Göksu River. The western part of the delta, which is the subject matter of this study, hosts fertile agricultural fields, touristic places and a Special Environmental Protection Area. These properties of the region lead to a water-dependent ecosystem where groundwater has widely been used for agricultural and domestic purposes. When the exploitation of groundwater peaked in the middle of 1990s, the groundwater levels dropped and seawater intruded. General Directorate of State Hydraulic Works tried to stop seawater intrusion by building irrigation channels connected to Göksu River and banned drilling of new wells for groundwater exploitation, although it is hard to control the drilling of wells without official permit. Geological studies show that the delta is composed of terrestrial sediments including clay to coarse sand deposited during Quaternary. The heterogeneous sediments of Göksu Delta cause hydrogeological features of the aquifer systems to be heterogeneous and anisotropic. Hydrogeological investigations, therefore, indicate mainly two different aquifers, shallow and deep, separated by an aquitard. The shallow aquifer is under unconfined to confined conditions from north to south while the deep aquifer is under confined conditions. This study focuses on hydrogeochemical zonation in terms of hydrochemical processes that affect the Göksu Delta aquifer systems. For this purpose, hydrogeochemical and isotopic studies are conducted to understand the salinisation and softening processes of groundwater. The physicochemical

  2. Summary and evaluation of hydraulic property data available for the Hanford Site upper basalt confined aquifer system

    SciTech Connect

    Spane, F.A. Jr.; Vermeul, V.R.

    1994-09-01

    Pacific Northwest Laboratory, as part of the Hanford Site Ground-Water Surveillance Project, examines the potential for offsite migration of contamination within the upper basalt confined aquifer system. For the past 40 years, hydrologic testing of the upper basalt confined aquifer has been conducted by a number of Hanford Site programs. Hydraulic property estimates are important for evaluating aquifer flow characteristics (i.e., ground-water flow patterns, flow velocity, transport travel time). Presented are the first comprehensive Hanford Site-wide summary of hydraulic properties for the upper basalt confined aquifer system (i.e., the upper Saddle Mountains Basalt). Available hydrologic test data were reevaluated using recently developed diagnostic test analysis methods. A comparison of calculated transmissivity estimates indicates that, for most test results, a general correspondence within a factor of two between reanalysis and previously reported test values was obtained. For a majority of the tests, previously reported values are greater than reanalysis estimates. This overestimation is attributed to a number of factors, including, in many cases, a misapplication of nonleaky confined aquifer analysis methods in previous analysis reports to tests that exhibit leaky confined aquifer response behavior. Results of the test analyses indicate a similar range for transmissivity values for the various hydro-geologic units making up the upper basalt confined aquifer. Approximately 90% of the calculated transmissivity values for upper basalt confined aquifer hydrogeologic units occur within the range of 10{sup 0} to 10{sup 2} m{sup 2}/d, with 65% of the calculated estimate values occurring between 10{sup 1} to 10{sup 2} m{sup 2}d. These summary findings are consistent with the general range of values previously reported for basalt interflow contact zones and sedimentary interbeds within the Saddle Mountains Basalt.

  3. Performance evaluation of a reverse-gradient artificial recharge system in basalt aquifers of Maharashtra, India

    NASA Astrophysics Data System (ADS)

    Bhusari, Vijay; Katpatal, Y. B.; Kundal, Pradeep

    2016-12-01

    Drinking water scarcity in rural parts of central India in basaltic terrain is common. Most of the rural population depends on groundwater sources located in the fractured and weathered zone of the basaltic aquifers. Long-term indiscriminate withdrawal has caused an alarming rate of depletion of groundwater levels in both pre- and post-monsoon periods. The aquifer is not replenished through precipitation under natural conditions. To overcome this situation, an innovative artificial recharge system, called the reverse-gradient recharge system (RGRS), was implemented in seven villages of Wardha district of Maharashtra. The study described here presents a comparative analysis of recharge systems constructed in the year 2012 downstream of dug-well locations in these seven villages. The post-project comparative analysis reveals that the area of influence (AOI) of the groundwater recharge system, within which increases in groundwater levels and yield are observed, is directly related to the specific yield, thickness of the weathered and fractured zone, porosity, and transmissivity of the aquifer, showing high correlation coefficients of 0.92, 0.88, 0.85 and 0.83, respectively. The study indicates that the RGRS is most effective in vesicular weathered and fractured basalt, recording a maximum increase in well yield of 65-82 m3/day, while a minimum increase in yield of 15-30 m3/day was observed in weathered vesicular basalt. The comparative analysis thus identifies the controlling factors which facilitate groundwater recharge through the proposed RGRS. After implementation of these projects, the groundwater availability in these villages increased significantly, solving their drinking water problems.

  4. Determination of dominant biogeochemical processes in a contaminated aquifer-wetland system using multivariate statistical analysis

    USGS Publications Warehouse

    Baez-Cazull, S. E.; McGuire, J.T.; Cozzarelli, I.M.; Voytek, M.A.

    2008-01-01

    Determining the processes governing aqueous biogeochemistry in a wetland hydrologically linked to an underlying contaminated aquifer is challenging due to the complex exchange between the systems and their distinct responses to changes in precipitation, recharge, and biological activities. To evaluate temporal and spatial processes in the wetland-aquifer system, water samples were collected using cm-scale multichambered passive diffusion samplers (peepers) to span the wetland-aquifer interface over a period of 3 yr. Samples were analyzed for major cations and anions, methane, and a suite of organic acids resulting in a large dataset of over 8000 points, which was evaluated using multivariate statistics. Principal component analysis (PCA) was chosen with the purpose of exploring the sources of variation in the dataset to expose related variables and provide insight into the biogeochemical processes that control the water chemistry of the system. Factor scores computed from PCA were mapped by date and depth. Patterns observed suggest that (i) fermentation is the process controlling the greatest variability in the dataset and it peaks in May; (ii) iron and sulfate reduction were the dominant terminal electron-accepting processes in the system and were associated with fermentation but had more complex seasonal variability than fermentation; (iii) methanogenesis was also important and associated with bacterial utilization of minerals as a source of electron acceptors (e.g., barite BaSO4); and (iv) seasonal hydrological patterns (wet and dry periods) control the availability of electron acceptors through the reoxidation of reduced iron-sulfur species enhancing iron and sulfate reduction. Copyright ?? 2008 by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America. All rights reserved.

  5. Identifying aquifer type in fractured rock aquifers using harmonic analysis.

    PubMed

    Rahi, Khayyun A; Halihan, Todd

    2013-01-01

    Determining aquifer type, unconfined, semi-confined, or confined, by drilling or performing pumping tests has inherent problems (i.e., cost and complex field issues) while sometimes yielding inconclusive results. An improved method to cost-effectively determine aquifer type would be beneficial for hydraulic mapping of complex aquifer systems like fractured rock aquifers. Earth tides are known to influence water levels in wells penetrating confined aquifers or unconfined thick, low-porosity aquifers. Water-level fluctuations in wells tapping confined and unconfined aquifers are also influenced by changes in barometric pressure. Harmonic analyses of water-level fluctuations of a thick (~1000 m) carbonate aquifer located in south-central Oklahoma (Arbuckle-Simpson aquifer) were utilized in nine wells to identify aquifer type by evaluating the influence of earth tides and barometric-pressure variations using signal identification. On the basis of the results, portions of the aquifer responded hydraulically as each type of aquifer even though there was no significant variation in lithostratigraphy. The aquifer type was depth dependent with confined conditions becoming more prevalent with depth. The results demonstrate that harmonic analysis is an accurate and low-cost method to determine aquifer type.

  6. Recharge to the surficial aquifer system in Lee and Hendry counties, Florida

    USGS Publications Warehouse

    Krulikas, R.K.; Giese, G.L.

    1995-01-01

    Protection of ground-water recharge areas against contamination is of great interest in Florida, a State whose population depends heavily on ground water and that is experiencing rapid growth. The Florida Legislature is considering implementation of a tax incentive program to owners of high-rate recharge lands that remain undeveloped. High-rate recharge was arbitrarily set at 10 or more inches per year. The U.S. Geological Survey, in cooperation with the South Florida Water Management District, conducted a study to investigate the efficacy of several methods for estimating recharge to the surficial aquifer system in southwestern Florida and to map recharge at a scale of 1:100,000. Four maps were constructed at a scale of 1:100,000 for Lee and Hendry Counties, depicting the configuration of the water table of the surficial aquifer system, direction of ground-water flow, general soil characteristics, and recharge rates. Point recharge rates calculated for 25 sites in Lee County from comparisons of chloride concentrations in precipitation and in water from the surficial aquifer system ranged from 0.6 to 9.0 inches per year. Local recharge rates estimated by increases in flow along theoretical flow tubes in the surficial aquifer system were 8.0 inches per year in a part of Lee County and 8.2 inches per year in a part of Hendry County. Information on oxygen isotopes in precipitation and water from the surficial aquifer system was used to verify that the source of chlorides in the aquifer system was from precipitation rather than upward leakage of saline water. Soil maps and general topographic and hydrologic considerations were used with calculated point and local recharge rates to regionalize rates throughout Lee and Hendry Counties. The areas of greatest recharge were found in soils of flatwoods and sloughs, which were assigned estimated recharge rates of 0 to 10 inches per year. Soils of swamps and sloughs were assigned values of 0 to 3.0 inches per year; soils of

  7. The San Andreas Fault System, California, USA

    USGS Publications Warehouse

    Brown, R.D.; Wallace, R.E.; Hill, D.P.

    1992-01-01

    Geologists, seismologists, and geophysicists have intensively studied the San Andreas fault system for the past 20 to 30 years. Their goals were to learn more about damaging earthquakes, the behavior of major stirke-slip faults, and methods of reducing earthquake hazards in populated areas. Field geologic investigations, seismic networks, post-earthquake studies, precision geodetic surveys, and reflection and refraction seismic surveys are among the methods used to decipher the history, geometry, and mechanics of the system. -from Authors

  8. Contamination by Arsenate in Oxidizing Groundwater, Southern Gulf Coast Aquifer System, Texas

    NASA Astrophysics Data System (ADS)

    Gates, J. B.; Nicot, J.; Reedy, R. C.; Scanlon, B. R.

    2009-12-01

    Groundwater arsenic concentrations exceed the U.S. EPA maximum contaminant level for drinking water (10 μg/L) in about one-third of wells in the southern Gulf Coast Aquifer System (GCAS) in Texas, representing a potential public health hazard and an environmental compliance challenge to numerous small public water supply systems. The aim of this study is to better understand the hydrogeochemical mechanisms underpinning the widespread distribution of elevated groundwater arsenic concentrations in the region. Here we focus upon arsenic contamination in unconfined portions of the aquifer system. The investigation is based upon chemical analyses of a field transect of 27 groundwater samples collected from across three units of the GCAS; stratified water quality sampling from one additional well; and relevant water chemistry data from the Texas Water Development Board groundwater database (more than 500 samples). Chemical results from the field study showed that carbonate weathering and active recharge in the unconfined zone result in circum-neutral pH and oxidizing redox conditions, which are typically amenable to arsenic immobilization by adsorption of As(V) onto mineral oxides and clays. However, arsenic concentrations were found up to 129 μg/L (median 12 μg/L), and As(V) represented nearly 100% of total arsenic. Concentrations generally decreased with increasing distance from the Catahoula Formation (which contains abundant volcanic ash presumed to be the original arsenic source), through the overlying Jasper, Evangeline and Chicot Aquifers. Statistically significant pairwise correlations with arsenic were found for vanadium, silica and potassium, all of which were released during weathering of volcanic sediments and their degradation products. Silica that was co-released with arsenic may compete for sorption sites and reduce the capacity for arsenic adsorption. An important role for variable arsenic source availability was suggested by regional spatial

  9. Setback distances between small biological wastewater treatment systems and drinking water wells against virus contamination in alluvial aquifers.

    PubMed

    Blaschke, A P; Derx, J; Zessner, M; Kirnbauer, R; Kavka, G; Strelec, H; Farnleitner, A H; Pang, L

    2016-12-15

    Contamination of groundwater by pathogenic viruses from small biological wastewater treatment system discharges in remote areas is a major concern. To protect drinking water wells against virus contamination, safe setback distances are required between wastewater disposal fields and water supply wells. In this study, setback distances are calculated for alluvial sand and gravel aquifers for different vadose zone and aquifer thicknesses and horizontal groundwater gradients. This study applies to individual households and small settlements (1-20 persons) in decentralized locations without access to receiving surface waters but with the legal obligation of biological wastewater treatment. The calculations are based on Monte Carlo simulations using an analytical model that couples vertical unsaturated and horizontal saturated flow with virus transport. Hydraulic conductivities and water retention curves were selected from reported distribution functions depending on the type of subsurface media. The enteric virus concentration in effluent discharge was calculated based on reported ranges of enteric virus concentration in faeces, virus infectivity, suspension factor, and virus reduction by mechanical-biological wastewater treatment. To meet the risk target of <10(-4)infections/person/year, a 12 log10 reduction was required, using a linear dose-response relationship for the total amount of enteric viruses, at very low exposure concentrations. The results of this study suggest that the horizontal setback distances vary widely ranging 39 to 144m in sand aquifers, 66-289m in gravel aquifers and 1-2.5km in coarse gravel aquifers. It also varies for the same aquifers, depending on the thickness of the vadose zones and the groundwater gradient. For vulnerable fast-flow alluvial aquifers like coarse gravels, the calculated setback distances were too large to achieve practically. Therefore, for this category of aquifer, a high level of treatment is recommended before the

  10. Description and evaluation of the effects of urban and agricultural development on the surficial aquifer system, Palm Beach County, Florida

    USGS Publications Warehouse

    Miller, W.L.

    1988-01-01

    The surficial aquifer system in Palm Beach County was studied during 1982-85 to determine the effects of increased urban and agricultural development on groundwater levels, flow directions, and quality. The surficial aquifer system and its geologic matrix are divisible into three zones on the bases of relative permeabilities and lithologic characteristics. The two greatest water users in the county, public supply utilities and agricultural irrigators, increased total water withdrawals by 123 and 50%, respectively, during 1970-80. By 1980, 76% of public supply withdrawals were from zones I and II of the surficial aquifer system, whereas groundwater pumpage for irrigation decreased to 9% of the total irrigation water used. Increases in groundwater withdrawals for public supply were greatest in the southeast and central coastal parts of the county and served as an indicator for potential changes of flow directions and water quality in the surficial aquifer system. Residual seawater, emplaced in the aquifer system during the Pleistocene Epoch, is still prevalent in the central and western parts of Palm Beach County where low permeabilities in the geologic matrix have retarded its dilution. Chemical analyses of canal-water and groundwater samples collected in April 1984 were used to evaluate the effects of groundwater/surface water exchange on the quality of water during canal conveyance across the area containing residual seawater. (USGS)

  11. Assessing groundwater availability in the Northern Atlantic Coastal Plain aquifer system

    USGS Publications Warehouse

    Masterson, John P.; Pope, Jason P.; Monti, Jack; Nardi, Mark R.

    2011-01-01

    The U.S. Geological Survey's Groundwater Resources Program is conducting an assessment of groundwater availability throughout the United States to gain a better understanding of the status of the Nation's groundwater resources and how changes in land use, water use, and climate may affect those resources. The goal of this National assessment is to improve our ability to forecast water availability for future economic and environmental uses. Assessments will be completed for the Nation's principal aquifer systems to help characterize how much water is currently available, how water availability is changing, and how much water we can expect to have in the future (Reilly and others, 2008). The concept of groundwater availability is more than just how much water can be pumped from any given aquifer. Groundwater availability is a function of many factors, including the quantity and quality of water and the laws, regulations, economics, and environmental factors that control its use. The primary objective of the North Atlantic Coastal Plain groundwater-availability study is to identify spatial and temporal changes in the overall water budget by more fully determining the natural and human processes that control how water enters, moves through, and leaves the groundwater system. Development of tools such as numerical models can help hydrologists gain an understanding of this groundwater system, allowing forecasts to be made about the response of this system to natural and human stresses, and water quality and ecosystem health to be analyzed, throughout the region.

  12. Different spatial discretization methods of fault systems on heat transport processes in hard rock aquifers

    NASA Astrophysics Data System (ADS)

    Kruppa, Lisa; König, Christoph M.; Becker, Martin; Seidel, Torsten

    2016-04-01

    Most hard rock aquifers, which are important for geothermal use, contain fractures of different type and scale. These fault systems are of major significance for heat flow in the groundwater. The hydrogeological characterization of fault systems must therefore be part of any site investigation in hard rock aquifers and hydraulically important fault systems need to be appropriately represented in associated numerical models. This contribution discusses different spatial discretization methods of fault systems in three-dimensional groundwater models and their impact on the simulated groundwater flow field as well as density and viscosity dependent heat transport. The analysis includes a comparison of the convergence behavior and numerical stability of the different discretization methods. To ensure defendable results, the utilized numerical model SPRING was first verified against data from the Hydrocoin Level 1 Case 2 project. After verification, the software was used to evaluate the impact of different discretization strategies on steady-state and transient groundwater flow and transport model results. The results show a significant influence of the spatial discretization strategy on predicted flow rates and subsequent mass fluxes as well as energy balances.

  13. The hydrothermal system of Long Valley Caldera, California

    USGS Publications Warehouse

    Sorey, M.L.; Lewis, Robert Edward; Olmsted, F.H.

    1978-01-01

    Long Valley caldera, an elliptical depression covering 450 km 2 on the eastern front of the Sierra Nevada in east-central California, contains a hot-water convection system with numerous hot springs and measured and estimated aquifer temperatures at depths of 180?C to 280?C. In this study we have synthesized the results of previous geologic, geophysical, geochemical, and hydrologic investigations of the Long Valley area to develop a generalized conceptual and mathematical model which describes the gross features of heat and fluid flow in the hydrothermal system. Cenozoic volcanism in the Long Valley region began about 3.2 m.y. (million years) ago and has continued intermittently until the present time. The major event that resulted in the formation of the Long Valley caldera took place about 0.7 m.y. ago with the eruption of 600 km 3 or more of Bishop Tuff of Pleistocene age, a rhyolitic ash flow, and subsequent collapse of the roof of the magma chamber along one or more steeply inclined ring fractures. Subsequent intracaldera volcanism and uplift of the west-central part of the caldera floor formed a subcircular resurgent dome about 10 km in diameter surrounded by a moat containing rhyolitic, rhyodacitic, and basaltic rocks ranging in age from 0.5 to 0.05 m.y. On the basis of gravity and seismic studies, we estimate an aver- age thickness of fill of 2.4 km above the precaldera granitic and metamorphic basement rocks. A continuous layer of densely welded Bishop Tuff overlies the basement rocks, with an average thickness of 1.4 km; the fill above the welded Bishop Tuff consists of intercalated volcanic flows and tuffs and fluvial and lacustrine deposits. Assuming the average grain density of the fill is between 2.45 and 2.65 g/cm 3 , we calculate the average bulk porosity of the total fill as from 0.11 to 0.21. Comparison of published values of porosity of the welded Bishop Tuff exposed southeast of the caldera with calculated values indicates average bulk porosity

  14. Surface Drift of RAFOS Floats in the California Current System

    NASA Astrophysics Data System (ADS)

    Gates, D. C.; Collins, C. A.; Margolina, T.

    2011-12-01

    The patterns of surface drift of ninety RAFOS floats in the California Current System have been studied. The floats were launched in the California Undercurrent during 1992-2010 and were tracked by the ARGOS system when they surfaced at the end of their subsurface mission. The float hulls were glass cylinders which were 8.6 cm wide by 1.52 m long and floated with the upper 30 cm of the hull above water. The surface drift of these floats was typically equatorward in the California Current. However, some floats would flow poleward, others would drift westward into the North Pacific Gyre, and others with orbital cyclonic and/or anti-cyclonic motions. The duration of surface trajectories varied from as short as a period of days to approximately ten months. Forces on the floats included wind stress on the exposed hull and the drag of ocean currents on the subsurface hull. The latter included the Stokes drift associated with surface wind waves, Ekman flow caused by the stress of the wind on the ocean surface, and the currents associated with the general circulation of the ocean. Surface currents can be explained by calculating current direction and velocity from wind stress data. As a first step, the relationship between observed wind stress and the motion of the float is determined by assuming Ekman balance. Mesoscale effects, including eddies, are also considered in explaining the surface drift of the floats.

  15. Hydrogeology and ground-water availability in the carbonate aquifer system of Frederick County, Virginia

    USGS Publications Warehouse

    Harlow,, George E.; Orndorff, Randall C.; Nelms, David L.; Weary, David J.; Moberg, Roger M.

    2005-01-01

    The carbonate aquifer system of the northern Shenandoah Valley provides an important water supply to local communities, including Frederick County, Va., which depends on ground water as a source of water supply. The county and surrounding area are undergoing increased urbanization, and increased demands on the carbonate aquifer system are expected. A study was conducted between October 2000 and March 2004 by the U.S. Geological Survey (USGS), in cooperation with the County of Frederick, Va., to describe the hydrogeology and ground-water availability in the carbonate aquifer system underlying the county. The study area encompasses about 25 percent (105 square miles) of the county that is underlain by carbonate bedrock. The carbonate aquifer system of Frederick County is in the Shenandoah Valley region of the Valley and Ridge Physiographic Province. Approximately 10,000 feet of folded and fractured Middle Cambrian to Upper Ordovician sedimentary rocks are exposed and are overlain by Pleistocene (?) and Holocene surficial deposits. All geologic units in the study area are considered to be aquifers. The geologic units are generally unconfined, fractured-rock aquifers that are recharged by precipitation and discharge locally to streams and springs, and by evapotranspiration. Stream density in the carbonate study area is less than in the remainder of the county, which is underlain by siliciclastic rock units. Most streams flow normal to strike (from the northwest towards the southeast) across the study area. These streams are characterized by shallow incisement and are usually limited to a single stream channel. In the southern third of the study area, streams flow parallel to strike (from the northeast towards the southwest) towards the deeply intrenched Cedar Creek. Springs are commonly located at the start of flows for all streams in the carbonate study area, and spring discharges are often a large portion of the streamflow (especially during drought conditions). The

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

    USGS Publications Warehouse

    Bellino, Jason C.; Spechler, Rick M.

    2013-01-01

    The U.S. Army Corps of Engineers (USACE) has proposed dredging a 13-mile reach of the St. Johns River navigation channel in Jacksonville, Florida, deepening it to depths between 50 and 54 feet below North American Vertical Datum of 1988. The dredging operation will remove about 10 feet of sediments from the surficial aquifer system, including limestone in some locations. The limestone unit, which is in the lowermost part of the surficial aquifer system, supplies water to domestic wells in the Jacksonville area. Because of density-driven hydrodynamics of the St. Johns River, saline water from the Atlantic Ocean travels upstream as a saltwater “wedge” along the bottom of the channel, where the limestone is most likely to be exposed by the proposed dredging. A study was conducted to determine the potential effects of navigation channel deepening in the St. Johns River on salinity in the adjacent surficial aquifer system. Simulations were performed with each of four cross-sectional, variable-density groundwater-flow models, developed using SEAWAT, to simulate hypothetical changes in salinity in the surficial aquifer system as a result of dredging. The cross-sectional models were designed to incorporate a range of hydrogeologic conceptualizations to estimate the effect of uncertainty in hydrogeologic properties. The cross-sectional models developed in this study do not necessarily simulate actual projected conditions; instead, the models were used to examine the potential effects of deepening the navigation channel on saltwater intrusion in the surficial aquifer system under a range of plausible hypothetical conditions. Simulated results for modeled conditions indicate that dredging will have little to no effect on salinity variations in areas upstream of currently proposed dredging activities. Results also indicate little to no effect in any part of the surficial aquifer system along the cross section near River Mile 11 or in the water-table unit along the cross

  17. Hydrology of the unconfined aquifer system, Mullica River basin, New Jersey, 1991-92

    USGS Publications Warehouse

    Johnson, Melissa L.; Watt, Martha K.

    1996-01-01

    The Kirkwood-Cohansey aquifer system, an unconfined aquifer system, is a major source of water in the Mullica River Basin in southern New Jersey. A water-level map was constructed from water levels measured in 197 wells and at 156 stream sites in the basin. Water levels in six observation wells were evaluated for seasonal fluctuations. The horizontal hydraulic conductivity of the unconfined aquifer ranges from 20 to 130 feet per day. Mean annual discharge at three streamflow-gaging stations in the Mullica River Basin during 1928-91 was 106 cubic feet per second; annual base flow at these three stations during 1928-91 ranged from 34 to 149 cubic feet per second. Mean discharge and base flow at 17 low-flow partial-record sites were determined by means of low-flow-correlation analyses. Mean annual precipitation in the study area, measured at 3 weather stations, was 45 inches during 1927-91. Annual potential evapotranspiration is estimated to be 28 inches. Twenty-five ground- and 14 surface-water-sampling sites were selected for water-quality analysis. The predominant cation in the ground and surface water is sodium; the predominant anion in the surface water is chloride and the predominant anions in the ground water are chloride and sulfate. Total consumptive water use in the study area is estimated to be more than 3,300 million gallons per year: 526 million gallons for public and private domestic water supply, 2,768 million gallons for for irrigation, and 18 million gallons for industry and mining. A water budget calculated for the Mullicat River Basin indicates that ground-water recharge is about 19 inches per year.

  18. Summary of the hydrology of the Floridan aquifer system in Florida and in parts of Georgia, South Carolina, and Alabama

    USGS Publications Warehouse

    Johnston, Richard H.; Bush, Peter W.

    1988-01-01

    The Floridan aquifer system is one of the major sources of ground-water supplies in the United States. This highly productive aquifer system underlies all of Florida, southern Georgia, and small parts of adjoining Alabama and South Carolina, for a total area of about 100,000 square miles. About 3 billion gallons of water per day is withdrawn from the aquifer for all uses, and, in many areas, the Floridan is the sole source of freshwater. The aquifer system is a sequence of hydraulically connected carbonate rocks (principally limestone and some dolomite) that generally range in age from Late Paleocene to Early Miocene. The rocks vary in thickness from a featheredge where they crop out to more than 3,500 ft where the aquifer is deeply buried. The aquifer system generally consists of an upper aquifer and a lower aquifer, separated by a less permeable confining unit of highly variable properties. In parts of north Florida and southwest Georgia, there is little permeability contrast within the aquifer system. Thus in these areas the Floridan is effectively one continuous aquifer. The upper and lower aquifers are defined on the basis of permeability, and their boundaries locally do not coincide with those for either time-stratigraphic or rock-stratigraphic units. Low-permeability clastic rocks overlie much of the Floridan aquifer system. The lithology, thickness, and integrity of these low-permeability rocks have a controlling effect on the development of permeability and ground-water flow in the Floridan locally. The Floridan aquifer system derives its permeability from openings that vary from fossil hashes and networks of many solution-widened joints to large cavernous openings in karst areas. Diffuse flow pre-dominates where the small openings occur, whereas conduit flow may occur where there are large cavernous openings. For the Upper Floridan aquifer, transmissivities are highest (greater than 1,000,000 ft squared per day) in the unconfined karst areas of central

  19. Quality of water recovered from a municipal effluent injection well in the Floridan aquifer system, Pompano Beach, Florida

    USGS Publications Warehouse

    McKenzie, D.J.; Irwin, G.A.

    1984-01-01

    Approximately 69 million gallons of backflow from an injection well used for the disposal of secondary treated municipal effluent in the Floridan aquifer system near Pompano Beach, Florida, was periodically sampled for inorganic quality from March 1975 through March 1977. Analyses of the backflow effluent showed a concomitant increase in dissolved solids and a change in ionic composition as a function of cumulative volume of backflow. Both the increase in dissolved solids and the change in major ionic composition were directly related to an estimated 6 to 7 percent mixing of the moderately saline water in the Florida aquifer system with the injected system with the injected effluent. Although an estimated 3.5 billion gallons of effluent was injected into the aquifer system during the 16-year operation of the Collier Manor treatment plant, only 65 to 70 million gallons was backflowed before the chloride concentration approached 250 milligrams per liter. (USGS)

  20. Assessment of groundwater availability in the Northern Atlantic Coastal Plain aquifer system From Long Island, New York, to North Carolina

    USGS Publications Warehouse

    Masterson, John P.; Pope, Jason P.; Fienen, Michael N.; Monti, Jr., Jack; Nardi, Mark R.; Finkelstein, Jason S.

    2016-08-31

    Executive SummaryThe U.S. Geological Survey began a multiyear regional assessment of groundwater availability in the Northern Atlantic Coastal Plain (NACP) aquifer system in 2010 as part of its ongoing regional assessments of groundwater availability of the principal aquifers of the Nation. The goals of this national assessment are to document effects of human activities on water levels and groundwater storage, explore climate variability effects on the regional water budget, and provide consistent and integrated information that is useful to those who use and manage the groundwater resource. As part of this nationwide assessment, the USGS evaluated available groundwater resources within the NACP aquifer system from Long Island, New York, to northeastern North Carolina.The northern Atlantic Coastal Plain physiographic province depends heavily on groundwater to meet agricultural, industrial, and municipal needs. The groundwater assessment of the NACP aquifer system included an evaluation of how water use has changed over time; this evaluation primarily used groundwater budgets and development of a numerical modeling tool to assess system responses to stresses from future human uses and climate trends.This assessment focused on multiple spatial and temporal scales to examine changes in groundwater pumping, storage, and water levels. The regional scale provides a broad view of the sources and demands on the system with time. The sub-regional scale provides an evaluation of the differing response of the aquifer system across geographic areas allowing for closer examination of the interaction between different aquifers and confining units and the changes in these interactions under pumping and recharge conditions in 2013 and hydrologic stresses as much as 45 years in the future. By focusing on multiple scales, water-resource managers may utilize this study to understand system response to changes as they affect the system as a whole.The NACP aquifer system extends from

  1. A Science Plan for a Comprehensive Regional Assessment of the Atlantic Coastal Plain Aquifer System in Maryland

    USGS Publications Warehouse

    Shedlock, Robert J.; Bolton, David W.; Cleaves, Emery T.; Gerhart, James M.; Nardi, Mark R.

    2007-01-01

    The Maryland Coastal Plain region is, at present, largely dependent upon ground water for its water supply. Decades of increasing pumpage have caused ground-water levels in parts of the Maryland Coastal Plain to decline by as much as 2 feet per year in some areas of southern Maryland. Continued declines at this rate could affect the long-term sustainability of ground-water resources in Maryland's heavily populated Coastal Plain communities and the agricultural industry of the Eastern Shore. In response to a recommendation in 2004 by the Advisory Committee on the Management and Protection of the State's Water Resources, the Maryland Geological Survey and the U.S. Geological Survey have developed a science plan for a comprehensive assessment that will provide new scientific information and new data management and analysis tools for the State to use in allocating ground water in the Coastal Plain. The comprehensive assessment has five goals aimed at improving the current information and tools used to understand the resource potential of the aquifer system: (1) document the geologic and hydrologic characteristics of the aquifer system in the Maryland Coastal Plain and appropriate areas of adjacent states; (2) conduct detailed studies of the regional ground-water-flow system and water budget for the aquifer system; (3) improve documentation of patterns of water quality in all Coastal Plain aquifers, including the distribution of saltwater; (4) enhance ground-water-level, streamflow, and water-quality-monitoring networks in the Maryland Coastal Plain; and (5) develop science-based tools to facilitate sound management of the ground-water resources in the Maryland Coastal Plain. The assessment, as designed, will be conducted in three phases and if fully implemented, is expected to take 7 to 8 years to complete. Phase I, which was initiated in January 2006, is an effort to assemble all the information and investigation tools needed to do a more comprehensive assessment of

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

    USGS Publications Warehouse

    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

  3. Conceptual Model of Hydrologic and Thermal Conditions of the Eastbank Aquifer System near Rocky Reach Dam, Douglas County, Washington

    USGS Publications Warehouse

    van Heeswijk, Marijke; Cox, Stephen E.; Huffman, Raegan L.; Curran, Christopher A.

    2008-01-01

    The Lower and Combined Aquifers of the Eastbank Aquifer system, located in a river-terrace deposit along the Columbia River near Rocky Reach Dam, Washington, are primarily recharged by the Columbia River and provide water to the Eastbank Hatchery and the regional water system servicing the cities of Wenatchee, East Wenatchee, and parts of unincorporated Chelan and Douglas Counties. In 2006, mean annual pumpage from the aquifers by the hatchery and regional water system was about 43 and 16 cubic feet per second, respectively. Reportedly, temperatures of ground water pumped by the hatchery have been increasing, thereby making water potentially too warm for salmonid fish production. An evaluation of hourly ground-water and river temperatures from January 1991 through August 2007 indicates increasing interannual trends in temperatures in most of the Lower and Combined Aquifers from 1999 through 2006 that correspond to increasing trends in the annual mean and annual maximum river temperatures during the same period of 0.07 and 0.17?C per year, respectively. There were no trends in the annual minimum river temperatures from 1999 through 2006, and there were no trends in the annual minimum, mean, and maximum river temperatures from 1991 through 1998 and from 1991 through 2007. Increases in river temperatures from 1999 through 2006 are within the natural variability of the river temperatures. Most of the Lower and Combined Aquifers reached thermal equilibrium?defined by constant time lags between changes in river temperatures and subsequent changes in ground-water temperatures?during 1991?98. The only exceptions are the Combined Aquifer north of the well field of the regional water system, which had not reached thermal equilibrium by 2006, and the Lower Aquifer west of the well fields of the hatchery and the regional water system, which reached thermal equilibrium prior to 1991. Because most of the Lower and Combined Aquifers were in thermal equilibrium from 1999 through

  4. The chemical behavior of the transuranic elements and the barrier function in natural aquifer systems

    SciTech Connect

    Jewett, J.R.

    1997-09-17

    In a geological repository for long-lived radioactive wastes, such as actinides and certain fission products, most of the stored radionuclides remain immobile in the particular geological formation. If any of these could possibly become mobile, only trace concentrations of a few radionuclides would result. Nevertheless, with an inventory in the repository of many tonnes of transuranic elements, the amounts that could disperse cannot be neglected. A critical assessment of the chemical behavior of these nuclides, especially their migration properties in the aquifer system around the repository site, is mandatory for analysis of the long-term safety. The chemistry requited for this includes many geochemical multicomponent reactions that are so far only partially understood and [which] therefore can be quantified only incompletely. A few of these reactions have been discussed in this paper based on present knowledge. If a comprehensive discussion of the subject is impossible because of this [lack of information], then an attempt to emphasize the importance of the predominant geochemical reactions of the transuranic elements in various aquifer systems should be made.

  5. Recharge Regimes of the Saq Aquifer System, Saudi Arabia: Inferences from Geochemical and Isotopic Compositions

    NASA Astrophysics Data System (ADS)

    Abouelmagd, A.; McCabe, M. F.; Castro, M. C.; Sultan, M.; Jana, R. B.; Al-Mashharawi, S.

    2014-12-01

    One of the most valuable groundwater reserves in Saudi Arabia is the Saq aquifer system (SAS), a thick (400-1200 meters) sandstone unit that extends across 300,000 km2 in Saudi Arabia and neighboring Jordan. Due to its high productivity and high water quality, current pumping and overexploitation of the aquifer has significantly lowered the groundwater level over the years. Understanding the recharge regimes of the SAS is critical for the development of sustainable exploitation of water resources in the region and for the establishment of appropriate management practices. In this study, we investigate the hydrologic setting of the SAS and seek to differentiate the degree of paleo versus modern contributions using a range of geochemical approaches. Multiple groundwater samples were collected from deep production wells tapping the SAS at depths between 375-1800 m and across a range of locations. Samples were analyzed for their chemical concentrations, stable isotopic compositions (δ18O and δ2H), and dissolved noble gas concentrations and isotopic ratios. Examining these data identifies unmixed pools of fossil groundwater at deeper depths as well as mixed shallower systems that indicate contributions from modern precipitation. Through isotopic and noble gas analyses, the relative age and timing of these recharge events was examined and show contributions from both glacial and inter-glacial periods, with some modest contributions from modern meteoric sources.

  6. Iron in the aquifer system of Suffolk County, New York, 1990–98

    USGS Publications Warehouse

    Brown, Craig J.; Walter, Donald A.; Colabufo, Steven

    1999-01-01

    High concentrations of dissolved iron in ground water contribute to the biofouling of public-supply wells, and the treatment and remediation of biofouling are costly. Water companies on Long Island, N.Y., spend several million dollars annually to recondition, redevelop, and replace supply wells and distribution lines; treat dissolved iron with sequestering agents or by filtration; and respond to iron-related complaints by customers. This report summarizes the results of studies done by the U.S. Geological Survey, in cooperation with the Suffolk County Water Authority, to characterize the geochemistry and microbiology of iron in the aquifer system of Suffolk County. This information should be helpful for the siting and operation of supply wells.Concentrations of dissolved iron in Long Island's ground water, and the frequency of iron biofouling of wells, are highest in ground-water-discharge zones, particularly near the south shore. Ground water along a deep north-south flowpath of the Magothy aquifer in southwestern Suffolk County becomes anaerobic (oxygen deficient) and Fe(III) reducing at a distance of 8 to 10 kilometers south of the ground-water divide, and this change coincides with the downgradient increase in dissolved iron concentrations. The distribution of organic carbon, and the distribution and local variations in reactivity of Fe(III), in Magothy aquifer sediments have resulted in localized differences in redox microenvironments. For example, Fe(III)-reducing zones are associated with anaerobic conditions, where relatively large amounts of Fe(III) oxyhydroxide grain coatings are present, whereas sulfate-reducing zones are associated with lignite-rich lenses of silt and clay and appear to have developed in response to the depletion of available Fe(III) oxyhydroxides. The sulfate-reducing zones are characterized by relatively low concentrations of dissolved iron (resulting from iron-disulfide precipitation) and may be large enough to warrant water

  7. Iron in the aquifer system of Suffolk County, New York, 1990-98

    USGS Publications Warehouse

    Brown, Craig J.; Walter, Donald A.; Colabufo, Steven

    1999-01-01

    High concentrations of dissolved iron in ground water contribute to the biofouling of public-supply wells, and the treatment and remediation of biofouling are costly. Water companies on Long Island, N.Y., spend several million dollars annually to recondition, redevelop, and replace supply wells and distribution lines; treat dissolved iron with sequestering agents or by filtration; and respond to iron-related complaints by customers. This report summarizes the results of studies done by the U.S. Geological Survey, in cooperation with the Suffolk County Water Authority, to characterize the geochemistry and microbiology of iron in the aquifer system of Suffolk County. This information should be helpful for the siting and operation of supply wells. Concentrations of dissolved iron in Long Island?s ground water, and the frequency of iron biofouling of wells, are highest in ground-water-discharge zones, particularly near the south shore. Ground water along a deep north-south flowpath of the Magothy aquifer in southwestern Suffolk County becomes anaerobic (oxygen deficient) and Fe(III) reducing at a distance of 8 to 10 kilometers south of the ground-water divide, and this change coincides with the downgradient increase in dissolved iron concentrations. The distribution of organic carbon, and the distribution and local variations in reactivity of Fe(III), in Magothy aquifer sediments have resulted in localized differences in redox microenvironments. For example, Fe(III)-reducing zones are associated with anaerobic conditions, where relatively large amounts of Fe(III) oxyhydroxide grain coatings are present, whereas sulfate-reducing zones are associated with lignite-rich lenses of silt and clay and appear to have developed in response to the depletion of available Fe(III) oxyhydroxides. The sulfate-reducing zones are characterized by relatively low concentrations of dissolved iron (resulting from iron-disulfide precipitation) and may be large enough to warrant water

  8. Configuration of the base of the Edwards-Trinity aquifer system and hydrogeology of the underlying pre-Cretaceous rocks, west-central Texas

    USGS Publications Warehouse

    Barker, Rene A.; Ardis, Ann F.

    1992-01-01

    The most permeable pre-Cretaceous rocks are in the eastern half of the study area where they compose the Hickory aquifer (in Upper Cambrian rocks), Ellenburger-San Saba aquifer (Upper Cambrian- Lower Ordovician), and Marble Falls aquifer (Lower Pennsylvanian). These aquifers are hydraulically connected to the northeastern fringe of the Edwards-Trinity aquifer system, as their up-turned margins crop out around the flanks of the breached Llano uplift. The Rustler aquifer in rocks of Late Permian age underlies parts of the Trans-Pecos region, where it yields small amounts of greatly mineralized water for industrial and agricultural purposes. The Dockum aquifer in rocks of Late Triassic age directly underlies the Edwards-Trinity aquifer system in western parts of the study area, and locally increases the saturated thickness of the ground-water-flow system by an average of about 200 feet. Despite these notable exceptions, the collective effect of the pre-Cretaceous rocks is that 01 a barrier to ground-water flow, which limits the exchange of water across the base of the Edwards-Trinity aquifer system.

  9. The Beijing Geothermal System, PR China: Natural state and exploitation modelling study of a low temperature basement aquifer system

    SciTech Connect

    Hochstein, M.P.; Zhongke, Yang

    1988-01-01

    Computer modeling of the Beijing low temperature, basement aquifer system has shown that secular natural convection of meteoric waters down to depths greater than 5 km can produce a temperature field which is similar to that observed in deep wells. Secular convection occurs within a crustal block with the approximate dimensions of 45 km {times} 60 km {times} 10 km; the Beijing system is probably one of the largest secular convecting systems described so far. It is driven entirely by the crustal heatflow which appears to be slightly lower (i.e. 54 mW/m{sup 2}) than the average continental heat flux. Several geophysical implications are described.

  10. Hydrogeophysical Data Fusion and Geostatistical Approach to Characterize Hydrogeological Structure of the Baton Rouge Aquifer System in Louisiana

    NASA Astrophysics Data System (ADS)

    Elshall, A. S.; Tsai, F. T.; Hanor, J. S.

    2012-12-01

    The complex siliciclastic aquifer system underneath the Baton Rouge area, Louisiana is fluvial in origin and is characterized by strongly binary heterogeneity of sandy units and mudstones as pervious and impervious hydrofacies. Two distinct east-west trending geologic faults, the Baton Rouge fault and the Denham Springs-Scotlandville fault, cut across East Baton Rouge Parish. Data from the USGS water wells suggest that the Baton Rouge fault is a low permeable fault that historically separates a sequence of freshwater aquifers north of the fault from brackish aquifers south of the fault. However, the Denham Springs-Scotlandville fault appears to be pervious. In this study we utilize wireline geophysical data and lithologic data to characterize the Baton Rouge aquifer system and delineate flow pathways thought the faults. To avoid non-uniqueness associated with the use of a single geophysical data type particularly with the presence of salinization, we interpret the sand and shale hydrofacies for each well log based on wireline short normal electrical resistivity, single-point resistance, spontaneous-potential and gamma ray. For geological model calibration we use lithologic data from drillers logs representing the actual lithology with depth. Using geophysical data for hydrogeological structure construction and using lithologic data for model calibration, we implement a generalized parameterization indicator scheme. First, we show that this methodology can effectively analyze a binary siliciclastic aquifer by depicting the spatial extent of major water bearing units, their interconnections and preferential flow paths within each unit. Second, mapping of the binary fault stratigraphy assists in the assessment of hydraulic continuity and saltwater intrusion in the siliciclastic aquifer system, which exhibits discontinuous heterogeneity due to fault throw. By juxtaposing sand units from both sides of the fault plane, horizontal flow pathways are identified if sands

  11. Hydrogeology and the distribution of salinity in the Floridan Aquifer system, southwestern Florida

    USGS Publications Warehouse

    Reese, R.S.

    2000-01-01

    In most of the study area, the Floridan aquifer system can be divided into a brackish-water zone, a salinity transition zone, and a saline-water zone. The brackish-water zone contains water with a dissolved-solids concentration of less than 10,000 milligrams per liter. The saline-water zone has a dissolved-solids concentration of at least 35,000 milligrams per liter and a salinity similar to that of seawater. The salinity transition zone that separates these two zones is usually 150 feet or less in thickness. The altitude of the base of the brackish-water zone was mapped primarily using geophysical logs; it ranges from as shallow as 565 feet below sea level along the coast to almost 2,200 feet below sea level inland. This mapping indicated that the boundary represents a salinity interface, the depth of which is controlled by head in the brackish-water zone. Chloride concentrations in the upper part of the brackish-water zone range from 400 to 4,000 milligrams per liter. A large area of relatively low salinity in north-central Collier County and to the northwest, as defined by a 1,200-milligram-per-liter chloride-concentration line, coincides with a high area on the basal contact of the Hawthorn Group. As this contact dips away from this high area to central Hendry and southwestern Collier Counties, chloride concentration increases to 2,000 milligrams per liter or greater. However, the increase in salinity in these areas occurs only in the basal Hawthorn unit or Suwannee Limestone, but not in deeper units. In central Hendry County, the increase occurs only in the basal Hawthorn unit in an area where the unit is well developed and thick. These areas of higher salinity could have resulted from the influx of seawater from southwestern Collier County into zones of higher permeability in the Upper Floridan aquifer during high sea-level stands. The influx may only have occurred in structurally low areas and may have experienced incomplete flushing subsequently by the

  12. Geologic Setting and Hydrogeologic Units of the Columbia Plateau Regional Aquifer System, Washington, Oregon, and Idaho

    USGS Publications Warehouse

    Kahle, Sue C.; Olsen, Theresa D.; Morgan, David S.

    2009-01-01

    The Columbia Plateau Regional Aquifer System (CPRAS) covers approximately 44,000 square miles of northeastern Oregon, southeastern Washington, and western Idaho. The area supports a $6 billion per year agricultural industry, leading the Nation in production of apples and nine other commodities (State of Washington Office of Financial Management, 2007; U.S. Department of Agriculture, 2007). Groundwater availability in the aquifers of the area is a critical water-resource management issue because the water demand for agriculture, economic development, and ecological needs is high. The primary aquifers of the CPRAS are basalts of the Columbia River Basalt Group (CRBG) and overlying basin-fill sediments. Water-resources issues that have implications for future groundwater availability in the region include (1) widespread water-level declines associated with development of groundwater resources for irrigation and other uses, (2) reduction in base flow to rivers and associated effects on temperature and water quality, and (3) current and anticipated effects of global climate change on recharge, base flow, and ultimately, groundwater availability. As part of a National Groundwater Resources Program, the U.S. Geological Survey began a study of the CPRAS in 2007 with the broad goals of (1) characterizing the hydrologic status of the system, (2) identifying trends in groundwater storage and use, and (3) quantifying groundwater availability. The study approach includes documenting changes in the status of the system, quantifying the hydrologic budget for the system, updating the regional hydrogeologic framework, and developing a groundwater-flow simulation model for the system. The simulation model will be used to evaluate and test the conceptual model of the system and later to evaluate groundwater availability under alternative development and climate scenarios. The objectives of this study were to update the hydrogeologic framework for the CPRAS using the available

  13. The effect of artesian-pressure decline on confined aquifer systems and its relation to land subsidence

    USGS Publications Warehouse

    Green, J.H.

    1964-01-01

    Ground water in the Southwestern United States is derived chiefly from unconsolidated to semiconsolidated alluvial deposits. Where these deposits contain confined water, they may be susceptible to compaction and related land- surface subsidence, if artesian pressures are reduced. Compaction of artesian-aquifer systems can be estimated from core tests if the artesian-pressure decline is known. Compaction occurs chiefly in the finer grained deposits ; porosity decrease is greater near the top of the confined aquifer than near the bottom. Because most of the compaction of these aquifer systems is permanent, the storage coefficient during the initial decline of artesian pressure greatly exceeds the storage coefficient during a subsequent pressure decline through the same depth range, after an intervening period of pressure recovery.

  14. Hydrogeologic framework and geologic structure of the Floridan aquifer system and intermediate confining unit in the Lake Okeechobee area, Florida

    USGS Publications Warehouse

    Reese, Ronald S.

    2014-01-01

    The successful implementation of aquifer storage and recovery (ASR) as a water-management tool requires detailed information on the hydrologic and hydraulic properties of the potential water storage zones. This report presents stratigraphic and hydrogeologic sections of the upper part of the Floridan aquifer system and the overlying confining unit or aquifer system in the Lake Okeechobee area, and contour maps of the upper contacts of the Ocala Limestone and the Arcadia Formation, which are represented in the sections. The sections and maps illustrate hydrogeologic factors such as confinement of potential storage zones, the distribution of permeability within the zones, and geologic features that may control the efficiency of injection, storage, and recovery of water, and thus may influence decisions on ASR activities in areas of interest to the Comprehensive Everglades Restoration Plan.

  15. A Laboratory Scale Aquifer-Well System for Analyzing Near-well Processes

    NASA Astrophysics Data System (ADS)

    Kalwa, Fritz; Bonilla, José; Händel, Falk; Binder, Martin; Stefan, Catalin

    2016-04-01

    Managed Aquifer Recharge (MAR) is constantly gaining popularity and one very promising technique in this context is infiltration by vertical wells. However, the near-well surrounding of these wells is still object of many open questions, related to - among others - clogging, screen design and the effects of underground heterogeneities. As a tool for a better understanding of these processes, a physical laboratory-scale aquifer-well model was designed. The physical model was assembled in a cylindrical tank with a height of 1.1 m and a diameter of 1 m. Water can be introduced via a small-diameter well screen (inner diameter: 2.54 cm) in the center of the tank and leaves the system via side outlets. These outlets were connected hydraulically to a single outflow system, allowing the adjustment of the same outflow head for all side outlets. Furthermore, a drainage system was attached to the tank's wall to assure circular flow from the well to the wall. The drainage system was chosen after preliminary tests of different drainage materials to determine the best performing setup. Remaining impoundment heights of up to 30 cm were observed in the tank, due to pressure losses at the outflow system. To include the resulting impoundment into a numerical model using Hydrus 2D/3D, a half-empirical formula was derived, plotting impoundment heights against infiltration rates and considering the pressure losses in the outflow system as well as in the drainage layer. Using the predicted impoundment heights for correction, the numerical model allowed satisfying simulation of the flow pattern in the tank for infiltration rates. The study shows how to develop an approach combining numerical and physical modeling as a base for future investigation of near-well processes under well-defined laboratory conditions.

  16. Sustainable development and management of an aquifer system in western Turkey

    NASA Astrophysics Data System (ADS)

    Sakiyan, Jale; Yazicigil, Hasan

    This study presents the establishment of sustainable development and management policies for the Küçük Menderes River Basin aquifer system in western Turkey. Geological, hydrogeological, and geophysical data are used conjunctively to define various hydrogeological units and their geometry. Distributions of hydraulic-parameter values and recharge are estimated by geostatistical methods and hydrologic simulations, respectively. A finite-difference groundwater flow model is used to represent the unconfined flow in the aquifer system. The model has been calibrated under steady state and transient conditions. The resulting model was used to test seven management scenarios for a planning period of 21 years to determine the so-called safe yield and sustainable yield of the aquifer system and to investigate the potential impacts of four planned surface water reservoirs on groundwater resources in the basin. The results demonstrate that the continuation of the present pumping rates exceeds both the safe yield and the sustainable yield of the aquifer system. Consequently, the growing need for irrigation water should be met by the construction of the planned surface water reservoirs and the implementation of efficient water management policies and plans. Cette étude présente la proposition d'une politique de développement et de gestion durables du système aquifère du bassin du Petit Mendérès dans l'ouest de la Turquie. Des données géologiques, hydrogéologiques et géophysiques ont été utilisées conjointement pour définir les différentes unités hydrogéologiques et leur géométrie. Les distributions des paramètres hydrauliques et de la recharge ont été estimées respectivement par des méthodes géostatistiques et des simulations hydrologiques. Un modèle d'écoulement souterrain aux éléments finis a été utilisé pour représenter l'écoulement non captif dans le système aquifère. Le modèle a été calibré dans des conditions de r

  17. Integrated hydrologic modeling of a transboundary aquifer system —Lower Rio Grande

    USGS Publications Warehouse

    Hanson, Randall T.; Schmid, Wolfgang; Knight, Jacob E.; Maddock, Thomas

    2013-01-01

    For more than 30 years the agreements developed for the aquifer systems of the lower Rio Grande and related river compacts of the Rio Grande River have evolved into a complex setting of transboundary conjunctive use. The conjunctive use now includes many facets of water rights, water use, and emerging demands between the states of New Mexico and Texas, the United States and Mexico, and various water-supply agencies. The analysis of the complex relations between irrigation and streamflow supplyand-demand components and the effects of surface-water and groundwater use requires an integrated hydrologic model to track all of the use and movement of water. MODFLOW with the Farm Process (MFFMP) provides the integrated approach needed to assess the stream-aquifer interactions that are dynamically affected by irrigation demands on streamflow allotments that are supplemented with groundwater pumpage. As a first step to the ongoing full implementation of MF-FMP by the USGS, the existing model (LRG_2007) was modified to include some FMP features, demonstrating the ability to simulate the existing streamflow-diversion relations known as the D2 and D3 curves, departure of downstream deliveries from these curves during low allocation years and with increasing efficiency upstream, and the dynamic relation between surface-water conveyance and estimates of pumpage and recharge. This new MF-FMP modeling framework can now internally analyze complex relations within the Lower Rio Grande Hydrologic Model (LRGHM_2011) that previous techniques had limited ability to assess.

  18. Understanding changes in the hydrological behaviour within a karst aquifer (Lurbach system, Austria).

    PubMed

    Mayaud, Cyril; Wagner, Thomas; Benischke, Ralf; Birk, Steffen

    2016-01-01

    A thorough data analysis combined with groundwater modelling was conducted in an Austrian binary karst aquifer to better understand changes in the hydrological behaviour observed at a karst spring. During a period of 4 years after a major flood event the spring hydrograph appears to be more damped with lower peak flow and higher baseflow than in the years before. The analysis of the hydrograph recession suggests that the observed hydrological change is caused by changes within the karst system rather than by varying hydro-meteorological conditions. The functioning of the aquifer and potential causes of the observed changes are further examined using the groundwater flow model MODFLOW. The simulation results suggest that a modification of hydraulic conductivity and storage within the conduit network, e.g. due to the plugging of the drainage conduits with sediments, may be the cause of the different behaviour. MODFLOW was able to reproduce the observed dynamics of spring flow, although it does not account for turbulent flow within karst conduits. Using a simplified model scenario it is demonstrated that the damping of the hydrograph is much stronger if turbulent conduit flow is taken into account. Thus, a turbulent flow model is needed to assess potential changes in the storage properties quantitatively.

  19. Mercury concentrations in water from an unconfined aquifer system, New Jersey coastal plain

    USGS Publications Warehouse

    Barringer, J.L.; Szabo, Z.; Kauffman, L.J.; Barringer, T.H.; Stackelberg, P.E.; Ivahnenko, T.; Rajagopalan, S.; Krabbenhoft, D.P.

    2005-01-01

    Concentrations of total mercury (Hg) from 2 ??g/L (the USEPA maximum contaminant level) to 72 ??g/L in water from about 600 domestic wells in residential parts of eight counties in southern New Jersey have been reported by State and county agencies. The wells draw water from the areally extensive (7770 km2) unconfined Kirkwood-Cohansey aquifer system, in which background concentrations of Hg are about 0.01 ??g/L or less. Hg is present in most aquifer materials at concentrations 0.1 ??g/L did not correlate significantly with concentrations of the inorganic constituents. Hgf concentrations near or exceeding 2 ??g/L were found only in water from wells in areas with residential land use, but concentrations were at background levels in most water samples from undeveloped land. The spatial distribution of Hg-contaminated ground water appears to be locally and regionally heterogeneous; no extensive plumes of Hg contamination have yet been identified. ?? 2004 Elsevier B.V. All rights reserved.

  20. A Weather Analysis and Forecasting System for Baja California, Mexico

    NASA Astrophysics Data System (ADS)

    Farfan, L. M.

    2006-05-01

    The weather of the Baja California Peninsula, part of northwestern Mexico, is mild and dry most of the year. However, during the summer, humid air masses associated with tropical cyclones move northward in the eastern Pacific Ocean. Added features that create a unique meteorological situation include mountain ranges along the spine of the peninsula, warm water in the Gulf of California, and the cold California Current in the Pacific. These features interact with the environmental flow to induce conditions that play a role in the occurrence of localized, convective systems during the approach of tropical cyclones. Most of these events occur late in the summer, generating heavy precipitation, strong winds, lightning, and are associated with significant property damage to the local populations. Our goal is to provide information on the characteristics of these weather systems by performing an analysis of observations derived from a regional network. This includes imagery from radar and geostationary satellite, and data from surface stations. A set of real-time products are generated in our research center and are made available to a broad audience (researchers, students, and business employees) by using an internet site. Graphical products are updated anywhere from one to 24 hours and includes predictions from numerical models. Forecasts are derived from an operational model (GFS) and locally generated simulations based on a mesoscale model (MM5). Our analysis and forecasting system has been in operation since the summer of 2005 and was used as a reference for a set of discussions during the development of eastern Pacific tropical cyclones. This basin had 15 named storms and none of them made landfall on the west coast of Mexico; however, four systems were within 800 km from the area of interest, resulting in some convective activity. During the whole season, a group of 30 users from our institution, government offices, and local businesses received daily information

  1. California's county hospitals and the University of California graduate medical education system. Current issues and future directions.

    PubMed Central

    Jameson, W J; Pierce, K; Martin, D K

    1998-01-01

    California's county hospitals train 45% of the state's graduate medical residents, including 33% of residents in the University of California system. This paper describes the interrelationships of California's county hospitals and the University of California (UC) graduate medical education (GME) programs, highlighting key challenges facing both systems. The mission of California's county health care systems is to serve all who need health care services regardless of ability to pay. Locating UC GME programs in county hospitals helps serve the public missions of both institutions. Such partnerships enhance the GME experience of UC residents, provide key primary care training opportunities, and ensure continued health care access for indigent and uninsured populations. Only through affiliation with university training programs have county hospitals been able to run the cost-effective, quality programs that constitute an acceptable safety net for the poor. Financial stress, however, has led county hospitals and UC's GME programs to advocate for reform in both GME financing and indigent care funding. County hospitals must participate in constructing strategies for GME reform to assure that GME funding mechanisms provide for equitable compensation of county hospitals' essential role. Joint advocacy will also be essential in achieving significant indigent care policy reform. PMID:9614786

  2. Hydrostratigraphic Framework and Selection and Correlation of Geophysical Log Markers in the Surficial Aquifer System, Palm Beach County, Florida

    USGS Publications Warehouse

    Reese, Ronald S.; Wacker, Michael A.

    2007-01-01

    The surficial aquifer system is the major source of freshwater for public water supply in Palm Beach County, Florida, yet many previous studies of the hydrogeology of this aquifer system have focused only on the eastern one-half to one-third of the county in the more densely populated coastal area (Land and others, 1973; Swayze and others, 1980; Swayze and Miller, 1984; Shine and others, 1989). Population growth in the county has resulted in the westward expansion of urbanized areas into agricultural areas and has created new demands on the water resources of the county. Additionally, interest in surface-water resources of central and western areas of the county has increased. In these areas, plans for additional surface-water storage reservoirs are being made under the Comprehensive Everglades Restoration Plan originally proposed by the U.S. Army Corps of Engineers and the South Florida Water Management District (1999), and stormwater treatment areas have been constructed by the South Florida Water Management District. Surface-water and ground-water interactions in the Everglades are thought to be important to water budgets, water quality, and ecology (Harvey and others, 2002). Most of the previous hydrogeologic and ground-water flow simulation studies of the surficial aquifer system have not utilized a hydrostratigraphic framework, in which stratigraphic or sequence stratigraphic units, such as those proposed in Cunningham and others (2001), are delineated in this stratigraphically complex aquifer system. A thick zone of secondary permeability mapped by Swayze and Miller (1984) was not subdivided and was identified as only being within the Anastasia Formation of Pleistocene age. Miller (1987) published 11 geologic sections of the surficial aquifer system, but did not delineate any named stratigraphic units in these sections. This limited interpretation has resulted, in part, from the complex facies changes within rocks and sediments of the surficial aquifer

  3. Aquifer-nomenclature guidelines

    USGS Publications Warehouse

    Laney, R.L.; Davidson, C.B.

    1986-01-01

    Guidelines and recommendations for naming aquifers are presented to assist authors of geohydrological reports in the United States Geological Survey, Water Resources Division. The hierarchy of terms that is used for water- yielding rocks from largest to smallest is aquifer system, aquifer, and zone. If aquifers are named, the names should be derived from lithologic terms, rock-stratigraphic units, or geographic names. The following items are not recommended as sources of aquifer names: time-stratigraphic names, relative position, alphanumeric designations, depositional environment, depth of occurrence, acronyms, and hydrologic conditions. Confining units should not be named unless doing so clearly promotes understanding of a particular aquifer system. Sources of names for confining units are similar to those for aquifer names, i.e. lithologic terms, rock-stratigraphic units or geographic names. Examples of comparison charts and tables that are used to define the geohydrologic framework are included. Aquifers are defined in 11 hypothetical examples that characterize geohydrologic settings throughout the country. (Author 's abstract)

  4. Detection of Septic System Waste in the Groundwaters of Southern California Using Emerging Contaminants and Isotopic Tracers

    NASA Astrophysics Data System (ADS)

    Huang, W.; Conkle, J.; Sickman, J. O.; Lucero, D.; Pang, F.; Gan, J.

    2011-12-01

    In California, groundwater supplies 30-40% of the State's water and in rapidly growing regions like the Inland Empire, groundwater makes up 80-90% of the municipal water supply. However, anthropogenic contamination could adversely affect groundwater quality and thereby reduce available supplies. Appropriate tracers are needed to identify groundwater contamination and protect human health. Stable isotopes δ15N and δ 18O offer unique information about the importance of nitrate sources and processes affecting nitrate in aquifers. We investigated the influence of septic systems on groundwater quality in and around the city of Beaumont, CA during 2010-11. Groundwater samples were collected from 38 active wells and 10 surface water sites in the region (urban and natural streams, agricultural drainage and groundwater recharge basins supplied by the California State Water Project). Stable isotopes and pharmaceuticals and personal care products (PPCPs) were analyzed for all the water samples. The variations of δ15N and δ 18O of nitrate were 2 - 21 per mil and -4 - 9 per mil respectively. δ15N-NO3 values greater than 10 per mil have been associated with nitrate inputs from sewage and animal waste, but in the Beaumont wells, PPCP concentrations were at or below the detection limit in most wells with high isotope ratios. We also observed a strong linear relationship between δ15N and δ 18O of nitrate (slope of~ 0.5) in the vast majority of our samples including those with high isotope ratios. Our results suggest that denitrification was widespread in the Beaumont aquifer and strongly affected the isotope composition of nitrate. In some wells, PPCPs (carbamazepine, sulfamethoxazole, primidone, meprobamate and diuron) and isotope measurements indicated inputs from human waste, but these sites were affected primarily by local waste-water treatment plant effluent. A mixing model was developed using multiple tracers to determine sources and contributions of groundwater

  5. Numerical analysis of the hydrogeologic controls in a layered coastal aquifer system, Oahu, Hawaii, USA

    NASA Astrophysics Data System (ADS)

    Oki, Delwyn S.; Souza, William R.; Bolke, Edward L.; Bauer, Glenn R.

    The coastal aquifer system of southern Oahu, Hawaii, USA, consists of highly permeable volcanic aquifers overlain by weathered volcanic rocks and interbedded marine and terrestrial sediments of both high and low permeability. The weathered volcanic rocks and sediments are collectively known as caprock, because they impede the free discharge of groundwater from the underlying volcanic aquifers. A cross-sectional groundwater flow and transport model was used to evaluate the hydrogeologic controls on the regional flow system in southwestern Oahu. Controls considered were: (a) overall caprock hydraulic conductivity; and (b) stratigraphic variations of hydraulic conductivity in the caprock. Within the caprock, variations in hydraulic conductivity, caused by stratigraphy or discontinuities of the stratigraphic units, are a major control on the direction of groundwater flow and the distribution of water levels and salinity. Results of cross-sectional modeling confirm the general groundwater flow pattern that would be expected in a layered coastal system. Groundwater flow is: (a) predominantly upward in the low-permeability sedimentary units; and (b) predominantly horizontal in the high-permeability sedimentary units. Résumé Le système aquifère littoral du sud d'Oahu (Hawaii, États-Unis) est constitué par des aquifères de terrains volcaniques très perméables, recouverts par des roches volcaniques altérées, et interstratifiés avec des sédiments marins et continentaux de perméabilité aussi bien forte que faible. Les roches volcaniques altérées et les sédiments sont globalement considérés comme une couverture, parce qu'ils s'opposent à l'écoulement de l'eau souterraine provenant des aquifères volcaniques sous-jacents. Les contrôles hydrogéologiques sur le système aquifère régional du sud-ouest d'Oahu ont étéévaluées au moyen d'un modèle d'écoulement et de transport sur une section transversale. Ces contrôles prennent en compte la conductivit

  6. Regional-Scale Controls on Arsenic Contamination in the Multi-Aquifer System of the Mekong Delta, Vietnam

    NASA Astrophysics Data System (ADS)

    Erban, L.; Gorelick, S.; Fendorf, S. E.

    2014-12-01

    Geogenic groundwater arsenic poses a considerable health threat to a large, largely agrarian population in the Mekong Delta, Vietnam. Demand for groundwater continues to rise despite limited information about where arsenic contamination occurs and how it may be affected by excessive pumping. We investigate arsenic measurements from over >40,000 wells found throughout the Delta's seven major exploited aquifers, relating trends in contamination to ancillary physico-chemical datasets. Logistic regression modeling shows that among wells in the most shallow aquifers, arsenic occurrence above the WHO standard (10 µg/L) is best described by a well's distance to 1) the Mekong River network and 2) delta front, its depth and location within fault-bounded areas of the delta. The shallow model is inadequate to capture contaminant occurrence in deeper aquifers (generally 200-500m) where wells are rarely contaminated except in near-river areas undergoing heavy pumping. Our results are the first to quantify how the probability of arsenic contamination varies in 3D throughout the complex aquifer system in relation to both natural and anthropogenically-mediated factors, and suggest that excessive extraction may be degrading the quality of deep aquifers. Findings may serve as a baseline for managing groundwater use for optimal human welfare and assessing any future changes in arsenic occurrence.

  7. Hybrid energy system cost analysis: San Nicolas Island, California

    SciTech Connect

    Olsen, T.L.; McKenna, E.

    1996-07-01

    This report analyzes the local wind resource and evaluates the costs and benefits of supplementing the current diesel-powered energy system on San Nicolas Island, California (SNI), with wind turbines. In Section 2.0 the SNI site, naval operations, and current energy system are described, as are the data collection and analysis procedures. Section 3.0 summarizes the wind resource data and analyses that were presented in NREL/TP 442-20231. Sections 4.0 and 5.0 present the conceptual design and cost analysis of a hybrid wind and diesel energy system on SNI, with conclusions following in Section 6. Appendix A presents summary pages of the hybrid system spreadsheet model, and Appendix B contains input and output files for the HYBRID2 program.

  8. Water resources of the Southern Hills regional aquifer system, southeastern Louisiana

    USGS Publications Warehouse

    White, Vincent E.

    2017-03-01

    Information concerning the availability, use, and quality of groundwater in the 10 parishes overlying the Southern Hills regional aquifer system of Louisiana (fig. 1) is critical for water-supply management. The purpose of this fact sheet is to present information that can be used by water managers, residents, and others for stewardship of this vital resource. Information on the availability, past and current use, use trends, and water quality from groundwater sources in these parishes is presented. Previously published reports (see References Cited section) and data stored in the U.S. Geological Survey’s National Water Information System (U.S. Geological Survey, 2017) are the primary sources of the information presented here.

  9. Interaction of cold-water aquifers with exploited reservoirs of the Cerro Prieto geothermal system

    USGS Publications Warehouse

    Truesdell, Alfred; Lippmann, Marcelo

    1990-01-01

    Cerro Prieto geothermal reservoirs tend to exhibit good hydraulic communication with adjacent cool groundwater aquifers. Under natural state conditions the hot fluids mix with the surrounding colder waters along the margins of the geothermal system, or discharge to shallow levels by flowing up fault L. In response to exploitation reservoir pressures decrease, leading to changes in the fluid flow pattern in the system and to groundwater influx. The various Cerro Prieto reservoirs have responded differently to production, showing localized near-well or generalized boiling, depending on their access to cool-water recharge. Significant cooling by dilution with groundwater has only been observed in wells located near the edges of the field. In general, entry of cool water at Cerro Prieto is beneficial because it tends to maintain reservoir pressures, restrict boiling, and lengthen the life and productivity of wells.

  10. Geohydrology and simulated effects of withdrawals on the Miocene aquifer system in the Mississippi Gulf Coast area

    USGS Publications Warehouse

    Sumner, D.M.; Wasson, B.E.; Kalkhoff, S.J.

    1987-01-01

    Intense development of the Miocene aquifer system for water supplies along the Mississippi Gulf Coast has resulted in large water level declines that have altered the groundwater flow pattern in the area. Water levels in some Miocene aquifers have declined about 2 ft/year since 1940; declines exceed 100 ft (80 ft sea level) in large areas along the coast. Water levels in the surficial aquifer system, generally less than 20 ft below land surface, have not declined. The Miocene and younger interbedded and lenticular sands and clays crop out in southern Mississippi and dip to the south and southwest. These sediments have large vertical variations in head and locally respond to stresses as separate aquifers. Freshwater recharge to the Miocene aquifer system primarily is from rainfall on the surficial aquifers. The water generally moves to the south and southeast along the bedding planes toward the Mississippi Gulf Coast where the water is either withdrawn by wells, discharges to the ocean, or gradually percolates upward into overlying aquifers. Drawdowns caused by large groundwater withdrawals along the coast probably have resulted in the gradual movement of the saltwater toward the pumping centers. In parts of the Miocene aquifer system commonly used for water supplies, the water generally is a sodium bicarbonate type. Increasing chloride concentrations in a few wells indicate that saline water is migrating into parts of all layers in the Pascagoula area. A quasi three-dimensional numerical model of the groundwater flow system was constructed and calibrated on the basis of the both pre- and post-development conditions. The effects of an expected 1.5% annual increase in groundwater withdrawals during the period 1985-2005 were evaluated by the flow model. Additional water level declines expected by the year 2005 in response to estimated pumpage are as follows: Gulfport, 135 ft in layer 4; Biloxi-Gulfport area, 100 ft in layer 5 and 50 ft in layer 3; Pascagoula area, 40

  11. "Groundwater ages" of the Lake Chad multi-layer aquifers system inferred from 14C and 36Cl data

    NASA Astrophysics Data System (ADS)

    Bouchez, Camille; Deschamps, Pierre; Goncalves, Julio; Hamelin, Bruno; Seidel, Jean-Luc; Doumnang, Jean-Claude

    2014-05-01

    Assessment of recharge, paleo-recharge and groundwater residence time of aquifer systems of the Sahel is pivotal for a sustainable management of this vulnerable resource. Due to its stratified aquifer system, the Lake Chad Basin (LCB) offers the opportunity to assess recharge processes over time and to link climate and hydrology in the Sahel. Located in north-central Africa at the fringe between the Sahel and the Sahara, the lake Chad basin (LCB) is an endorheic basin of 2,5.106 km2. With a monsoon climate, the majority of the rainfall occurs in the southern one third of the basin, the Chari/Logone River system transporting about 90% of the runoff generated within the drainage basin. A complex multi-layer aquifer system is located in the central part of the LCB. The Quaternary unconfined aquifer, covering 500 000 km2, is characterized by the occurrence of poorly understood piezometric depressions. Artesian groundwaters are found in the Plio-Pleistocene lacustrine and deltaic sedimentary aquifers (early Pliocene and Continental Terminal). The present-day lake is in hydraulic contact with the Quaternary Aquifer, but during past megalake phases, most of the Quaternary aquifer was submerged and may experience major recharge events. To identify active recharge area and assess groundwater dynamics, one hundred surface and groundwater samples of all layers have been collected over the southern part of the LCB. Major and trace elements have been analyzed. Measurements of 36Cl have been carried out at CEREGE, on the French 5 MV AMS National Facility ASTER and 14C activities have been analyzed for 17 samples on the French AMS ARTEMIS. Additionally, the stable isotopic composition was measured on the artesian aquifer samples. In the Quaternary aquifer, results show a large scatter with waters having very different isotopic and geochemical signature. In its southern part and in the vicinity of the surface waters, groundwaters are predominantly Ca-Mg-HCO3 type waters with very

  12. The calculation of aquifer chemistry in hot-water geothermal systems

    USGS Publications Warehouse

    Truesdell, Alfred H.; Singers, Wendy

    1974-01-01

    The temperature and chemical conditions (pH, gas pressure, and ion activities) in a geothermal aquifer supplying a producing bore can be calculated from the enthalpy of the total fluid (liquid + vapor) produced and chemical analyses of water and steam separated and collected at known pressures. Alternatively, if a single water phase exists in the aquifer, the complete analysis (including gases) of a sample collected from the aquifer by a downhole sampler is sufficient to determine the aquifer chemistry without a measured value of the enthalpy. The assumptions made are that the fluid is produced from a single aquifer and is homogeneous in enthalpy and chemical composition. These calculations of aquifer chemistry involving large amounts of ancillary information and many iterations require computer methods. A computer program in PL-1 to perform these calculations is available from the National Technical Information Service as document PB-219 376.

  13. Potential Offshore Submarine Groundwater in the Albufeira-Ribeira de Quarteira aquifer system (Algarve, Portugal)

    NASA Astrophysics Data System (ADS)

    Hugman, Rui; Stigter, Tibor; Monteiro, Jose Paulo

    2015-04-01

    The Albufeira-Ribeira de Quarteira aquifer system on the south coast of Portugal is an important source of groundwater for agriculture and tourism, as well as contributing to significant freshwater discharge along the coast in the form of inter- and sub-tidal springs and maintaining groundwater dependent ecosystems along the Quarteira stream. Submarine groundwater discharge (SGD) in the area was investigated within the scope of a multidisciplinary research project FREEZE (PTDC/MAR/102030/2008) which aimed to identify and characterize the effects of the hydrological/hydrogeological conditions on associated ecosystems. As well as near shore submarine springs, signs of SGD were found several kilometres from the shoreline during offshore CTD and geophysical surveys. On-land geophysical and offshore seismic surveys supplied data to update the 3D hydrogeological conceptual model of the aquifer system. Numerical models were applied to test the possibility of an offshore continuation of fresh groundwater over several kilometres under local conditions. Due to the high computational demand of variable density modelling, in an initial phase simplified 2D cross section models were used to test the conceptual model and reduce uncertainty in regards to model parameters. Results confirm the potential for SGD several kilometres from the coast within a range of acceptable values of hydraulic conductivity and recharge of the system. This represents the initial step in developing and calibrating a 3D regional scale model of the system, which aims to supply an estimate of the spatial distribution of SGD as well as serve as a decision support tool for the local water resources management agency.

  14. Drought resilience of the California Central Valley surface-groundwater-conveyance system

    SciTech Connect

    Miller, N.L.; Dale, L.L.; Brush, C.; Vicuna, S.; Kadir, T.N.; Dogrul, E.C.; Chung, F.I.

    2009-05-15

    A series of drought simulations were performed for the California Central Valley using computer applications developed by the California Department of Water Resources and historical datasets representing a range of droughts from mild to severe for time periods lasting up to 60 years. Land use, agricultural cropping patterns, and water demand were held fixed at the 2003 level and water supply was decreased by amounts ranging between 25 and 50%, representing light to severe drought types. Impacts were examined for four hydrologic subbasins, the Sacramento Basin, the San Joaquin Basin, the Tulare Basin, and the Eastside Drainage. Results suggest the greatest impacts are in the San Joaquin and Tulare Basins, regions that are heavily irrigated and are presently overdrafted in most years. Regional surface water diversions decrease by as much as 70%. Stream-to-aquifer flows and aquifer storage declines were proportional to drought severity. Most significant was the decline in ground water head for the severe drought cases, where results suggest that under these scenarios the water table is unlikely to recover within the 30-year model-simulated future. However, the overall response to such droughts is not as severe as anticipated and the Sacramento Basin may act as ground-water insurance to sustain California during extended dry periods.

  15. Guide for data collection to calibrate a predictive digital ground-water model of the unconfined aquifer in and near the city of Modesto, California

    USGS Publications Warehouse

    Page, R.W.

    1977-01-01

    The city of Modesto encompasses about 12 square miles in the northeastern part of the San Joaquin Valley, Calif. The ground-water model encompasses about 542 square miles. In the Modesto area, ground water occurs in an unconfined aquifer a confined aquifer. both of which are composed of unconsolidated materials, and a consolidated-rock aquifer. Only the unconfined aquifer was modeled, using several simplifying assumptions concerning hydrologic conditions in the ground-water basin. A program is used that computes the net rate of recharge and discharge under steady-state conditions. The model was then modified until reasonable values of recharge and discharge were computed. Testing of the model indicated that simulated water levels were especially sensitive to tansmissivity, storage coefficient, irrigation return, and riverbed hydraulic conductivity; amond the parameters that affected water levels least were the vertical hydraulic conductivity and specific storage of the confining bed, the so-called E-clay. (Woodard-USGS)

  16. Hydrogeology and Simulation of Groundwater Flow in the Plymouth-Carver-Kingston-Duxbury Aquifer System, Southeastern Massachusetts

    USGS Publications Warehouse

    Masterson, John P.; Carlson, Carl S.; Walter, Donald A.; Other contributing authors: Bent, Gardner C.; Massey, Andrew J.

    2009-01-01

    The glacial sediments that underlie the Plymouth-Carver-Kingston-Duxbury area of southeastern Massachusetts compose an important aquifer system that is the primary source of water for a region undergoing rapid development. Population increases and land-use changes in this area has led to two primary environmental effects that relate directly to groundwater resources: (1) increases in pumping that can adversely affect environmentally sensitive groundwater-fed surface waters, such as ponds, streams, and wetlands; and (2) adverse effects of land use on the quality of water in the aquifer. In response to these concerns, the U.S. Geological Survey, in cooperation with the Massachusetts Department of Environmental Protection, began an investigation in 2005 to improve the understanding of the hydrogeology in the area and to assess the effects of changing pumping and recharge conditions on groundwater flow in the Plymouth-Carver-Kingston-Duxbury aquifer system. A numerical flow model was developed based on the USGS computer program MODFLOW-2000 to assist in the analysis of groundwater flow. Model simulations were used to determine water budgets, flow directions, and the sources of water to pumping wells, ponds, streams, and coastal areas. Model-calculated water budgets indicate that approximately 298 million gallons per day (Mgal/d) of water recharges the Plymouth-Carver-Kingston-Duxbury aquifer system. Most of this water (about 70 percent) moves through the aquifer, discharges to streams, and then reaches the coast as surface-water discharge. Of the remaining 30 percent of flow, about 25 percent of the water that enters the aquifer as recharge discharges directly to coastal areas and 5 percent discharges to pumping wells. Groundwater withdrawals are anticipated to increase from the current (2005) rate of about 14 Mgal/d to about 21 Mgal/d by 2030. Pumping from large-capacity production wells decreases water levels and increases the potential for effects on surface

  17. The quality of our Nation's waters: water quality in the Denver Basin aquifer system, Colorado, 2003-05

    USGS Publications Warehouse

    Bauch, Nancy J.; Musgrove, Marylynn; Mahler, Barbara J.; Paschke, Suzanne

    2015-01-01

    Availability and sustainability of groundwater in the Denver Basin aquifer system depend on water quantity and water quality. The Denver Basin aquifer system underlies about 7,000 square miles of the Great Plains in eastern Colorado and is the primary or sole source of water for domestic and public supply in many areas of the basin. Use of groundwater from the Denver Basin sandstone aquifers has been instrumental for development of the south Denver metropolitan area and other areas, but has resulted in a decline in water levels in some parts of the system. Human activities in many areas have adversely affected the quality of water in the aquifer system, especially the shallow parts. Groundwater in deeper parts of the system used for drinking water, once considered isolated from the effects of overlying land use, is increasingly vulnerable to contamination from human activities and geologic materials. Availability and sustainability of high-quality groundwater are vital to the economic health of the Denver Basin area.

  18. Modeling CO2 Sequestration in Saline Aquifer and Depleted Oil Reservoirs to Evaluate Regional CO2 Sequestration Potential of Ozark Plateau Aquifer System, South-Central Kansas

    NASA Astrophysics Data System (ADS)

    Watney, W. L.; Rush, J.

    2011-12-01

    The Paleozoic-age Ozark Plateau Aquifer System (OPAS) in southern Kansas consists of a thick (>450 m) and deeply buried (>1 km) succession of Cambro-Ordovician Arbuckle Group strata (dolomite) overlain by Lower Ordovician to Lower Carboniferous-age carbonate, chert, and shale. The Arbuckle Group is a thick widespread saline aquifer in southern Kansas. A 500 meter core of the OPAS interval and immediate overlying Pennsylvanian shale caprock were cored in early 2011 in the BEREXCO Wellington KGS #1-32 well in Wellington Field, a nearly depleted oil field in Sumner County, in south-central Kansas. An exhaustive set of modern logs were run in the KGS #1-32 well including chemical, microresistivity imaging, dipole sonic, nuclear magnetic resonance, and standard porosity and resistivity wireline logs. In addition, routine and special core analyses provide vital means to calibrate these logs. Core also provide vital chemical analyses and rock samples to run flow experiments, including in situ conditions, to establish reaction kinetics of rock and connate brines with CO2. Core and logs also provide the means to calibrate a 26 km2 multicomponent 3D seismic survey that was acquired in Wellington Field in 2010. Studies of four oil fields, also part of this project, are underway in southwestern Kansas to provide additional calibration points for the western part of the regional study that covers 65,000 km2 where CO2 sequestration capacity will be measured. Several hundred deep wells have been identified to serve as type wells in the regional study area. Well logs and sample descriptions are being digitized, correlated, and mapped to define distribution of aquifers, oil reservoirs, and caprocks. Drill stem test data have been analyzed for deep wells to establish that the Arbuckle is an open aquifer connected to surface exposures 100s of km to east in central Missouri. Over 500 km2 of 3D seismic have been donated by industrial partners to aid in understanding fault and fracture

  19. The California corridor transportation system: A design summary

    NASA Technical Reports Server (NTRS)

    1990-01-01

    A design group was assembled to find and research criteria relevent to the design of a California Corridor Transportation System. The efforts of this group included defining the problem, conducting a market analysis, formulation of a demand model, identification and evaluation of design drivers, and the systematic development of a solution. The problems of the current system were analyzed and used to determine design drivers, which were divided into the broad categories of cost, convenience, feasibility, environment, safety, and social impact. The relative importance of individual problems was addressed, resulting in a hierarchy of design drivers. Where possible, methods of evaluating the relative merit of proposed systems with respect to each driver were developed. Short takeoff vertical landing aircraft concepts are also discussed for supersonic fighters.

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

    USGS Publications Warehouse

    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.

  1. Summary of the Snake River plain Regional Aquifer-System Analysis in Idaho and eastern Oregon

    USGS Publications Warehouse

    Lindholm, G.F.

    1996-01-01

    Regional aquifers underlying the 15,600-square-mile Snake River Plain in southern Idaho and eastern Oregon was studied as part of the U.S. Geological Survey's Regional Aquifer-System Analysis program. The largest and most productive aquifers in the Snake River Plain are composed of Quaternary basalt of the Snake River Group, which underlies most of the 10,8000-square-mile eastern plain. Aquifer tests and simulation indicate that transmissivity of the upper 200 feet of the basalt aquifer in the eastern plain commonly ranges from about 100,000 to 1,000,000 feet squared per day. However, transmissivity of the total aquifer thickness may be as much as 10 million feet squared per day. Specific yield of the upper 200 feet of the aquifer ranges from about 0.01 to 0.20. Average horizontal hydraulic conductivity of the upper 200 feet of the basalt aquifer ranges from less than 100 to 9,000 feet per day. Values may be one to several orders of magnitude higher in parts in individual flows, such as flow tops. Vertical hydraulic conductivity is probably several orders of magnitude lower than horizontal hydraulic conductivity and is generally related to the number of joints. Pillow lava in ancestral Snake River channels has the highest hydraulic conductivity of all rock types. Hydraulic conductivity of the basalt decreases with depth because of secondary filling of voids with calcite and silica. An estimated 80 to 120 million acre-feet of water is believed to be stored in the upper 200 feet of the basalt aquifer in the eastern plain. The most productive aquifers in the 4,800-square-mile western plain are alluvial sand and gravel in the Boise River valley. Although aquifer tests indicate that transmissivity of alluvium in the Boise River valley ranges from 5,000 to 160,000 feet squared per day, simulation suggests that average transmissivity of the upper 500 feet is generally less than 20,000 feet squared per day. Vertically averaged horizontal hydraulic conductivity of the upper

  2. Mercury concentrations in water from an unconfined aquifer system, New Jersey coastal plain.

    PubMed

    Barringer, Julia L; Szabo, Zoltan; Kauffman, Leon J; Barringer, Thomas H; Stackelberg, Paul E; Ivahnenko, Tamara; Rajagopalan, Shilpa; Krabbenhoft, David P

    2005-06-15

    Concentrations of total mercury (Hg) from 2 microg/L (the USEPA maximum contaminant level) to 72 microg/L in water from about 600 domestic wells in residential parts of eight counties in southern New Jersey have been reported by State and county agencies. The wells draw water from the areally extensive (7770 km(2)) unconfined Kirkwood-Cohansey aquifer system, in which background concentrations of Hg are about 0.01 microg/L or less. Hg is present in most aquifer materials at concentrations <50 microg/kg, but is at 100--150 microg/kg in undisturbed surficial soils. No point sources of contamination to the affected areas have been conclusively identified. To determine whether high levels of Hg in ground water are related to a particular land use and (or) water chemistry, water samples from 105 wells that tap the aquifer system were collected by the United States Geological Survey. These included randomly selected domestic wells, domestic and observation wells in selected land uses, and sets of clustered observation wells--including two sets that are downgradient from residential areas with Hg-contaminated ground water. Hg concentrations in filtered samples (Hg(f)) were at or near background levels in water from most wells, but ranged from 0.1 to 3.8 microg/L in water from nearly 20% of wells. Hg(f) concentrations from 0.0001 to 0.1 microg/L correlated significantly and positively with concentrations of other constituents associated with anthropogenic inputs (Ca, Cl, Na, and NO(3)) and with dissolved organic carbon. Hg(f) concentrations >0.1 microg/L did not correlate significantly with concentrations of the inorganic constituents. Hg(f) concentrations near or exceeding 2 microg/L were found only in water from wells in areas with residential land use, but concentrations were at background levels in most water samples from undeveloped land. The spatial distribution of Hg-contaminated ground water appears to be locally and regionally heterogeneous; no extensive plumes of

  3. Preliminary delineation of natural geochemical reactions, Snake River Plain aquifer system, Idaho National Engineering Laboratory and vicinity, Idaho

    SciTech Connect

    Knobel, L.L.; Bartholomay, R.C.; Orr, B.R.

    1997-05-01

    The U.S. Geological Survey, in cooperation with the U.S. Department of Energy, is conducting a study to determine the natural geochemistry of the Snake River Plain aquifer system at the Idaho National Engineering Laboratory (INEL), Idaho. As part of this study, a group of geochemical reactions that partially control the natural chemistry of ground water at the INEL were identified. Mineralogy of the aquifer matrix was determined using X-ray diffraction and thin-section analysis and theoretical stabilities of the minerals were used to identify potential solid-phase reactants and products of the reactions. The reactants and products that have an important contribution to the natural geochemistry include labradorite, olivine, pyroxene, smectite, calcite, ferric oxyhydroxide, and several silica phases. To further identify the reactions, analyses of 22 representative water samples from sites tapping the Snake River Plain aquifer system were used to determine the thermodynamic condition of the ground water relative to the minerals in the framework of the aquifer system. Principal reactions modifying the natural geochemical system include congruent dissolution of olivine, diopside, amorphous silica, and anhydrite; incongruent dissolution of labradorite with calcium montmorillonite as a residual product; precipitation of calcite and ferric oxyhydroxide; and oxidation of ferrous iron to ferric iron. Cation exchange reactions retard the downward movement of heavy, multivalent waste constituents where infiltration ponds are used for waste disposal.

  4. Statistical analysis of aquifer-test results for nine regional aquifers in Louisiana

    USGS Publications Warehouse

    Martin, Angel; Early, D.A.

    1987-01-01

    This report, prepared as part of the Gulf Coast Regional Aquifer-System Analysis project, presents a compilation, summarization, and statistical analysis of aquifer-test results for nine regional aquifers in Louisiana. These are from youngest to oldest: The alluvial, Pleistocene, Evangeline, Jasper, Catahoula, Cockfield, Sparta, Carrizo, and Wilcox aquifers. Approximately 1,500 aquifer tests in U.S. Geological Survey files in Louisiana were examined and 1,001 were input to a computer file. Analysis of the aquifer test results and plots that describe aquifer hydraulic characteristics were made for each regional aquifer. Results indicate that, on the average, permeability (hydraulic conductivity) generally tends to decrease from the youngest aquifers to the oldest. The most permeable aquifers in Louisiana are the alluvial and Pleistocene aquifers; whereas, the least permeable are the Carrizo and Wilcox aquifers. (Author 's abstract)

  5. Digital surfaces and thicknesses of selected hydrogeologic units within the Ozark Plateaus aquifer system, northwestern Arkansas

    USGS Publications Warehouse

    Czarnecki, John B.; Bolyard, Susan E.; Hart, Rheannon M.; Clark, Jimmy M.

    2014-01-01

    Digital surfaces and thicknesses of nine hydrogeologic units of the Ozark Plateaus aquifer system from land surface to the top of the Gunter Sandstone in northwestern Arkansas were created using geophysical logs, drillers’ logs, geologist-interpreted formation tops, and previously published maps. The 6,040 square mile study area in the Ozark Plateaus Province includes Benton, Washington, Carroll, Madison, Boone, Newton, Marion, and Searcy Counties. The top of each hydrogeologic unit delineated on geophysical logs was based partly on previously published reports and maps and also from drillers’ logs. These logs were then used as a basis to contour digital surfaces showing the top and thickness of the Fayetteville Shale, the Boone Formation, the Chattanooga Shale, the Everton Formation, the Powell Dolomite, the Cotter Dolomite, the Roubidoux Formation, the Gasconade Dolomite, and the Gunter Sandstone.

  6. A Semi-Analytical Solution for Large-Scale Injection-Induced PressurePerturbation and Leakage in a Laterally Bounded Aquifer-AquitardSystem

    SciTech Connect

    Zhou, Quanlin; Birkholzer, Jens T.; Tsang, Chin-Fu

    2008-07-15

    A number of (semi-)analytical solutions are available to drawdown analysis and leakage estimation of shallow aquifer-aquitard systems. These solutions assume that the systems are laterally infinite. When a large-scale pumping from (or injection into) an aquifer-aquitard system of lower specific storativity occurs, induced pressure perturbation (or hydraulic head drawdown/rise) may reach the lateral boundary of the aquifer. We developed semi-analytical solutions to address the induced pressure perturbation and vertical leakage in a 'laterally bounded' system consisting of an aquifer and an overlying/underlying aquitard. A one-dimensional radial flow equation for the aquifer was coupled with a one-dimensional vertical flow equation for the aquitard, with a no-flow condition imposed on the outer radial boundary. Analytical solutions were obtained for (1) the Laplace-transform hydraulic head drawdown/rise in the aquifer and in the aquitard, (2) the Laplace-transform rate and volume of leakage through the aquifer-aquitard interface integrated up to an arbitrary radial distance, (3) the transformed total leakage rate and volume for the entire interface, and (4) the transformed horizontal flux at any radius. The total leakage rate and volume depend only on the hydrogeologic properties and thicknesses of the aquifer and aquitard, as well as the duration of pumping or injection. It was proven that the total leakage rate and volume are independent of the aquifer's radial extent and wellbore radius. The derived analytical solutions for bounded systems are the generalized solutions of infinite systems. Laplace-transform solutions were numerically inverted to obtain the hydraulic head drawdown/rise, leakage rate, leakage volume, and horizontal flux for given hydrogeologic and geometric conditions of the aquifer-aquitard system, as well as injection/pumping scenarios. Application to a large-scale injection-and-storage problem in a bounded system was demonstrated.

  7. Tabulated Transmissivity and Storage Properties of the Floridan Aquifer System in Florida and Parts of Georgia, South Carolina, and Alabama

    USGS Publications Warehouse

    Kuniansky, Eve L.; Bellino, Jason C.

    2012-04-19

    A goal of the U.S. Geological Survey Groundwater Resources Program is to assess the availability of fresh water within each of the principal aquifers in the United States with the greatest groundwater withdrawals. The Floridan aquifer system (FAS), which covers an area of approximately 100,000 square miles in Florida and parts of Georgia, Alabama, Mississippi, and South Carolina, is one such principal aquifer, having the fifth largest groundwater withdrawals in the Nation, totaling 3.64 billion gallons per day in 2000. Compilation of FAS hydraulic properties is critical to the development and calibration of groundwater flow models that can be used to develop water budgets spatially and temporally, as well as to evaluate resource changes over time. Wells with aquifer test data were identified as Upper Floridan aquifer (UFA), Lower Floridan aquifer (LFA), Floridan aquifer system (FAS, Upper Floridan with some middle and/or Lower Floridan), or middle Floridan confining unit (MCU), based on the identification from the original database or report description, or comparison of the open interval of the well with previously published maps.This report consolidates aquifer hydraulic property data obtained from multiple databases and reports of the U.S. Geological Survey, various State agencies, and the Water Management Districts of Florida, that are compiled into tables to provide a single information source for transmissivity and storage properties of the FAS as of October 2011. Transmissivity calculated from aquifer pumping tests and specific-capacity data are included. Values for transmissivity and storage coefficients are intended for use in regional or sub regional groundwater flow models; thus, any tests (aquifer pumping tests and specific capacity data) that were conducted with packers or for open intervals less than 30 feet in length are excluded from the summary statistics and tables of this report, but are included in the database.The transmissivity distribution

  8. Water quality of a stream-aquifer system, southern Franklin County, Ohio

    USGS Publications Warehouse

    De Roche, J.T.; Razem, A.C.

    1984-01-01

    The chemical quality of the water resources in the Scioto River valley south of Columbus, Ohio, was evaluated on the basis of data collected from 74 wells and 4 surface-water sites. A very hard calcium bicarbonate water that is high in dissolved solids is characteristic of the aquifer. Mean pH of the ground water is 7.3, and bicaerbonate concentrations range from 238 to 530 milligrams per liter. Concentrations of dissolved iron in water samples (0.01 to 3.9 milligrams per liter) frequently exceed the drinking water standard of 0.3 milligrams per liter established by the Ohio Environmental Protection Agency. The chemical quality of local streams closely resembles the ground-water quality, except for higher concentrations of sodium, chloride, and sulfate in the surface water. Microbiological testing of ground water for fecal bacteria indicated concentrations ranging from 1 to 2,400 colonies per 100 milliliters. The higher concentrations were observed in one well on the Scioto River flood plain after a flood event. Mass-balance calculations of the chemical data indicate that pH is buffered primarily by the carbonate system. Data for pH, calculated Eh, and concentrations of ferrous iron and reduced sulfur show that areas of different chemical environments exist within the aquifer. A reaction model of an induced-infiltration radial collector system indicates the amount of mass transfer (chemical reactions that occur as ground water and surface water mix) is small, and that the mixing ratio between ground and surface waters is four to one.

  9. Using a Geographic Information System to Assess Site Suitability for Managed Aquifer Recharge using Stormwater Capture

    NASA Astrophysics Data System (ADS)

    Teo, E. K.; Harmon, R. E.; Beganskas, S.; Young, K. S.; Fisher, A. T.; Weir, W. B.; Lozano, S.

    2015-12-01

    We are completing a regional analysis of Santa Cruz and northern Monterey Counties, CA, to assess the conditions amenable to managed aquifer recharge using stormwater runoff. Communities and water supply agencies across CA are struggling to mitigate the ongoing drought and to develop secure and sustainable water supplies to support long-term municipal, agricultural, environmental and other needs. Enhanced storage of groundwater is an important part of this effort in many basins. This work is especially timely because of the recently enacted "Sustainable Groundwater Management Act" (SGMA), which requires the development of groundwater sustainability agencies and implementation of basin management plans in coming decades. Our analysis focuses specifically on the distributed collection of stormwater runoff, a water source that has typically been treated as a nuisance or waste, from drainages having an area on the order of 40-160 hectares. The first part of this project is a geographic information system (GIS) analysis using surface and subsurface data sets. Developing complete and accurate datasets across the study region required considerable effort to locate, assemble, co-register, patch, and reconcile information from many sources and scales. We have complete spatial coverage for surface data, but subsurface data is more limited in lateral extent. Sites that are most suitable for distributed stormwater capture supporting MAR have high soil infiltration capacity, are well-connected to an underlying aquifer with good transmissive and storage properties, and have space to receive MAR. Additional considerations include method of infiltration, slope, and land use and access. Based on initial consideration of surface data and slope, 7% of the complete study region appears to be "suitable or highly suitable" for MAR (in the top third of the rating system), but there is considerable spatial heterogeneity based on the distribution of shallow soils and bedrock geology.

  10. Hydrochemical Regions of the Glacial Aquifer System, Northern United States, and Their Environmental and Water-Quality Characteristics

    USGS Publications Warehouse

    Arnold, Terri L.; Warner, Kelly L.; Groschen, George E.; Caldwell, James P.; Kalkhoff, Stephen J.

    2008-01-01

    The glacial aquifer system in the United States is a large (953,000 square miles) regional aquifer system of heterogeneous composition. As described in this report, the glacial aquifer system includes all unconsolidated geologic material above bedrock that lies on or north of the line of maximum glacial advance within the United States. Examining ground-water quality on a regional scale indicates that variations in the concentrations of major and minor ions and some trace elements most likely are the result of natural variations in the geologic and physical environment. Study of the glacial aquifer system was designed around a regional framework based on the assumption that two primary characteristics of the aquifer system can affect water quality: intrinsic susceptibility (hydraulic properties) and vulnerability (geochemical properties). The hydrochemical regions described in this report were developed to identify and explain regional spatial variations in ground-water quality in the glacial aquifer system within the hypothetical framework context. Data analyzed for this study were collected from 1991 to 2003 at 1,716 wells open to the glacial aquifer system. Cluster analysis was used to group wells with similar ground-water concentrations of calcium, chloride, fluoride, magnesium, potassium, sodium, sulfate, and bicarbonate into five unique groups. Maximum Likelihood Classification was used to make the extrapolation from clustered groups of wells, defined by points, to areas of similar water quality (hydrochemical regions) defined in a geospatial model. Spatial data that represented average annual precipitation, average annual temperature, land use, land-surface slope, vertical soil permeability, average soil clay content, texture of surficial deposits, type of surficial deposit, and potential for ground-water recharge were used in the Maximum Likelihood Classification to classify the areas so the characteristics of the hydrochemical regions would resemble the

  11. Summary of hydraulic properties of the Floridan Aquifer system in coastal Georgia and adjacent parts of South Carolina and Florida

    USGS Publications Warehouse

    Clarke, John S.; Leeth, David C.; Taylor-Harris, DaVette; Painter, Jaime A.; Labowski, James L.

    2005-01-01

    Hydraulic-property data for the Floridan aquifer system and equivalent clastic sediments in a 67-county area of coastal Georgia and adjacent parts of South Carolina and Florida were evaluated to provide data necessary for development of ground-water flow and solute-transport models. Data include transmissivity at 324 wells, storage coefficient at 115 wells, and vertical hydraulic conductivity of 72 core samples from 27 sites. Hydraulic properties of the Upper Floridan aquifer vary greatly in the study area due to the heterogeneity (and locally to anisotropy) of the aquifer and to variations in the degree of confinement provided by confining units. Prominent structural features in the areathe Southeast Georgia Embayment, the Beaufort Arch, and the Gulf Troughinfluence the thickness and hydraulic properties of the sediments comprising the Floridan aquifer system. Transmissivity of the Upper Floridan aquifer and equivalent updip units was compiled for 239 wells and ranges from 530 feet squared per day (ft2/d) at Beaufort County, South Carolina, to 600,000 ft2/d in Coffee County, Georgia. In carbonate rock settings of the lower Coastal Plain, transmissivity of the Upper Floridan aquifer generally is greater than 20,000 ft2/d, with values exceeding 100,000 ft2/d in the southeastern and southwestern parts of the study area (generally coinciding with the area of greatest aquifer thickness). Transmissivity of the Upper Floridan aquifer generally is less than 10,000 ft2/d in and near the upper Coastal Plain, where the aquifer is thin and consists largely of clastic sediments, and in the vicinity of the Gulf Trough, where the aquifer consists of low permeability rocks and sediments. Large variability in the range of transmissivity in Camden and Glynn Counties, Georgia, and Nassau County, Florida, demonstrates the anisotropic distribution of hydraulic properties that may result from fractures or solution openings in the carbonate rocks. Storage coefficient of the Upper

  12. Effects of natural and human factors on groundwater quality of basin-fill aquifers in the southwestern United States-conceptual models for selected contaminants

    USGS Publications Warehouse

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

    2011-01-01

    As part of the U.S. Geological Survey National Water-Quality Assessment (NAWQA) Program, the Southwest Principal Aquifers (SWPA) study is building a better understanding of the factors that affect water quality in basin-fill aquifers in the Southwestern United States. The SWPA study area includes four principal aquifers of the United States: the Basin and Range basin-fill aquifers in California, Nevada, Utah, and Arizona; the Rio Grande aquifer system in New Mexico and Colorado; and the California Coastal Basin and Central Valley aquifer systems in California. Similarities in the hydrogeology, land- and water-use practices, and water-quality issues for alluvial basins within the study area allow for regional analysis through synthesis of the baseline knowledge of groundwater-quality conditions in basins previously studied by the NAWQA Program. Resulting improvements in the understanding of the sources, movement, and fate of contaminants are assisting in the development of tools used to assess aquifer susceptibility and vulnerability. This report synthesizes previously published information about the groundwater systems and water quality of 15 information-rich basin-fill aquifers (SWPA case-study basins) into conceptual models of the primary natural and human factors commonly affecting groundwater quality with respect to selected contaminants, thereby helping to build a regional understanding of the susceptibility and vulnerability of basin-fill aquifers to those contaminants. Four relatively common contaminants