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At least 415 records · Page 23Linked to original sources
USGS1975

Summary appraisals of the nation's ground-water resources – Upper Mississippi region

The Upper Mississippi Region in general is rich in water-surface water is plentiful, and ground water is a large, important, and manageable resource. Total potable water in storage in the outwash and alluvial aquifers of the Mississippi River valley and the subbasins is about 45,000 billion gallons. This is about 10 percent of the water in storage in Lake Ontario. Water in storage in other aquifers of the region is probably at least several times that in the outwash and alluvial aquifers. Estimated ground-water recharge in the subbasins is 23,000 million gallons per day. A comparison of ground-water withdrawals with estimated ground-water recharge suggests that the large ground-water resource of the region is not being fully utilized. Ground-water use by domestic, commercial, and rural interests is only 4 percent of recharge. Ground-water use (1965) by industry is only 3 percent of recharge. Water in the outwash and alluvial aquifers of much of the valley of the Mississippi River in and south of St. Paul, Minn. of the Illinois River, the Lower Minnesota River, the Wisconsin River, the Lower Black River, the Wapsipinicon River, the Lower Rock River, and the Upper Des Moines River can be considered a regional resource. In these areas the ground-water resources are of sufficient magnitude to satisfy more than just local needs. For example, under certain specified conditions, ground water in the above areas can supply approximately 20 million additional people. Factors other than water supply, of course, will be constraints on development in the region. Advances in techniques in ground-water hydrology during recent years have provided methods that the hydrologist and planner can use for planning and design of ground-water developments. Therefore, the planner can now resolve some of the development and management questions that historically have bred uncertainty when this part of the water resource was considered for development.

Illinois, Indiana, Iowa, Missouri, Minnesota, Sout↗
USGS1976

Summary appraisals of the nation's ground-water resources–Texas-Gulf region

Ground water in the Texas-Gulf Region is a large and important resource that can provide a more significant percentage of the total water supply of the region. Total water requirements within the region are projected to rise sharply from 14 million acre-feet (17 cubic kilometres) in 1970 to nearly 26 million acre-feet (32 cubic kilometres) in 2020. About half of the water used in 1970 was ground water. An estimated total of 1.04 billion acre-feet (1,280 cubic kilometres) of recoverable water containing less than 3,000 milligrams per litre dissolved solids is stored above a depth of 400 feet (122 metres) in the aquifers of the region. In addition, part of an estimated 3.28 billion acre-feet (4,040 cubic kilometres) of water in storage below 400 feet (122 metres) is recoverable. Although not all of the ground water in storage is recoverable, a significant amount is available for development; and an enormous quantity is accessible should occasions prompt its use on a time-limited basis. The total steady-state yield (amount of water that approximates the maximum perennial replenishment from precipitation) of the region's aquifers is about 4.6 million acre-feet (5.7 cubic kilometres) annually, or about 2.3 times the ground-water usage in 1970 if the large mining draft on the High Plains is not considered as part of the total steady-state yield. Because of the large quantity of recoverable groundwater in storage, the steady-state yield can be augmented for a very long time on a "deferred" basis, whereby the economic use of the water that is withdrawn from storage in excess of the steady-state yield may result in a strengthened economy. An important goal in programs for meeting future water needs should be to identify the full potential of the available ground-water resources. The subsurface reservoirs may be utilized not only as sources of fresh and treatable water, but as storage facilities for other freshwater supplies and as possible sources of geothermal energy. Some saline-water reservoirs may be suitable for liquid-waste storage or disposal. Large-scale and unregulated ground-water pumping may result in hydrologic problems such as declining water levels, streamflow depletion, and land-surface subsidence; but studies on proper development of the ground-water reservoirs could provide solutions to many of the problems. Water rights and other legal concepts should be based on sound hydrologic principles to assist development of water resources in an orderly and efficient manner. Because significant amounts of ground water are available, the opportunities for expanded and conjunctive use of ground water and surface water should be considered in regional plans for water development and conservation. The complexities of water management and the difficulties of achieving an integrated system of total-water management will require additional technical information.

Louisiana, New Mexico, Texas↗
USGS1960

Ground-water hydrology and glacial geology of the Kalamazoo area, Michigan

The Kalamazoo report area includes about 150 square miles of Kalamazoo County, Mich. The area is principally one of industry and commerce, although agriculture also is of considerable importance. It has a moderate and humid climate and lies within the Lake Michigan “snow belt”. Precipitation averages about 35 inches per year. Snowfall averages about 55 inches. The surface features of the area were formed during and since the glacial epoch and are classified as outwash plain, morainal highlands, and glaciated channels or drainageways. The area is formed largely on the remnants of an extensive outwash plain, which is breached by the Kalamazoo River in the northeastern part and is dissected elsewhere by several small tributaries to the river. Most of the land drained by these tributaries lies within the report area. A small portion of the southern part drains to the St. Joseph River. The Coldwater shale, which underlies the glacial deposits throughout the area, and the deeper bedrock formations are not tapped for water by wells and they have little or no potential for future development. Deposits of glacial drift, which are the source of water to all the wells in the area, have considerable potential for future development. These deposits range in thickness from about 40 feet along the Kalamazoo River to 350 feet where valleys were eroded in the bedrock surface. Permeable outwash and channel deposits are the sources of water for wells of large capacity. The moraines are formed dominantly by till of lower permeability which generally yields small supplies of water, but included sand and gravel beds of higher permeability yield larger supplies locally. The aquifers of the Kalamazoo area are recharged by infiltration of rainfall and snowmelt and by infiltration of surface waters induced by pumping of wells near the surface sources. Water pumped from most of the municipal well fields is replenished in part by such induced infiltration. Many of the industrial wells along the Kalamazoo River and Portage Creek are recharged in part from these streams. Locally, however, recharge from the streams is impeded, as their bottoms have become partly sealed by silt and solid waste matter. Water levels fluctuate with seasonal and annual changes in precipitation and in response to pumping. Pumpage by the city of Kalamazoo increased from about 300 million gallons in 1880 to 4.6 billion gallons in 1957. Despite the fact that billions of gallons are pumped annually from well fields in the Axtell Creek area, water levels in this vicinity have declined only a few feet, as the discharge from the fields is approximately compensated by recharge from precipitation and surface water. Pumpage of ground water by industry in 1948 was estimated at about 14 billion gallons, but the use of ground water for industrial purposes has since declined. Aquifer tests indicate that the coefficient of transmissibility of aquifers in the area ranges from as little as 18,000 to as high as 300,000 gpd (gallons per day) per foot, and that ground water occurs under watertable and artesian conditions. The ground water is of the calcium magnesium bicarbonate type. It is generally hard to very hard and commonly contains objectionable amounts of iron. Locally, the water contains appreciable amounts of sulfate. Study of the chemical analyses of waters from the area show that all of the tributaries to the Kalamazoo River are fed primarily by ground-water discharge.

Michigan↗
USGS2004

Regional water table (2002) and water-level changes in the Mojave River and Morongo ground-water basins, southwestern Mojave Desert, California

The Mojave River and Morongo ground-water basins are in the southwestern part of the Mojave Desert in southern California. Ground water from these basins supplies a major part of the water requirements for the region. The continuous population growth in this area has resulted in ever-increasing demands on local ground-water resources. The collection and interpretation of ground-water data helps local water districts, military bases, and private citizens gain a better understanding of the ground-water flow systems, and consequently, water availability. During 2002, the U.S. Geological Survey and other agencies made approximately 2,500 water-level measurements in the Mojave River and Morongo ground-water basins. These data document recent conditions and, when compared with previous data, changes in ground-water levels. A water-level contour map was drawn using data from about 600 wells, providing coverage for most of the basins. Twenty-eight hydrographs show long-term (up to 70 years) water-level conditions throughout the basins, and 9 short-term (1997 to 2002) hydrographs show the effects of recharge and discharge along the Mojave River. In addition, a water-level-change map was compiled to compare 2000 and 2002 water levels throughout the basins. In the Mojave River ground-water basin, about 66 percent of the wells had water-level declines of 0.5 ft or more since 2000 and about 27 percent of the wells had water-level declines greater than 5 ft. The only area that had water-level increases greater than 5 ft that were not attributed to fluctuations in nearby pumpage was in the Harper Lake (dry) area where there has been a significant reduction in pumpage during the last decade. In the Morongo ground-water basin, about 36 percent of the wells had water-level declines of 0.5 ft or more and about 10 percent of the wells had water-level declines greater than 5 ft. Water-level increases greater than 5 ft were measured only in the Warren subbasin, where artificial-recharge operations have caused water levels to rise almost 60 ft since 2000.

Scientific Investigations Report↗
USGS1986

Water resources data, Florida, water year 1984. Volume 2B. South Florida ground water

Water resources data for the 1984 water year in Florida consists of continuous or daily discharge for 251 streams, periodic discharge for 32 streams, miscellaneous discharge for 43 stream, continuous or daily stage for 92 streams, periodic stage for 31 streams, peak discharge for 60 streams, and peak stage for 37 streams; continuous or daily elevations for 73 lakes, periodic elevations for 82 lakes; continuous ground water levels for 467 wells, and periodic ground water levels for 539 wells; and miscellaneous water level measurement for 2,039 wells; quality of water data for 200 surface water sites and 596 wells. The data for south Florida includes continuous or daily discharge for 74 streams, periodic discharge for 2 streams, peak discharge for 2 streams, continuous or daily stage for 76 streams, and periodic stage for 29 streams; continuous elevation for 18 lakes and periodic elevations for 5 lakes; continuous ground water levels for 180 wells, periodic ground water levels for 130 wells, and miscellaneous water level measurements for 360 wells; quality of water for 40 surface water sites and for 310 wells. These data represent the National Water Data System records collected by the U.S. Geological Survey and cooperating local, state, and federal agencies in Florida.

Florida↗
USGS2003

Water Resources Data, Florida, Water Year 2002, Volume 2B. South Florida Ground Water

Water resources data for 2002 water year in Florida consists of continuous or daily discharge for 392 streams, periodic discharge for 15 streams, continuous or daily stage for 191 streams, periodic stage for 13 stream, peak discharge for 33 streams, and peak stage for 33 streams, continuous or daily elevations for 14 lakes, periodic elevations for 49 lakes, continuous ground-water levels for 418 wells, periodic ground-water levels for 1287 wells, quality of water data for 116 surface-water sites, and 291 wells. The data for South Florida included continuous or daily discharge for 71 streams, continuous or daily stage for 49 streams, no peak stage discharge for streams, 1 continuous elevation for lake, continuous ground-water levels for 238 wells, periodic ground-water levels for 260 wells, water quality for 24 surface-water sites, and 159 wells. These data represent the National Water Data System records collected by the U.S. Geological Survey and cooperating local, State, and Federal agencies in Florida.

Water Data Report↗
USGS2006

Water resources data, Florida, water year 2005. Volume 1B: Northeast Florida ground water

Water resources data for the 2005 water year in Florida consist of continuous or daily discharge for 429 streams, periodic discharge for 9 streams, continuous or daily stage for 218 streams, periodic stage for 5 streams, peak stage and discharge for 28 streams; continuous or daily elevations for 15 lakes, periodic elevations for 23 lakes; continuous ground-water levels for 401 wells, periodic ground-water levels for 1,098 wells; quality-of-water data for 211 surface-water sites and 208 wells.The data for northeast Florida include continuous or daily discharge for 140 streams, periodic discharge for 4 streams, continuous or daily stage for 58 streams, periodic stage for 3 streams; peak stage and discharge for 0 streams; continuous or daily elevations for 10 lakes, periodic elevations for 20 lakes; continuous ground water levels for 45 wells, periodic ground-water levels for 520 wells; quality-of-water data for 40 surface-water sites and 65 wells.These data represent the National Water Data System records collected by the U.S. Geological Survey and cooperating local, State and Federal agencies in Florida.

Water Data Report↗
USGS2003

Water Resources Data, Florida, Water Year 2002, Volume 1B. Northeast Florida Ground Water

Water resources data for the 2002 water year in Florida consist of continuous or daily discharge for 392 streams, periodic discharge for 17 streams, continuous or daily stage for 191 streams, periodic stage for 13 streams, peak stage and discharge for 33 streams; continuous or daily elevations for 14 lakes, periodic elevations for 49 lakes; continuous ground-water levels for 418 wells, periodic ground-water levels for 1,287 wells; quality-of-water data for 116 surface-water sites and 291 wells. The data for northeast Florida include continuous or daily discharge for 155 streams, periodic discharge for 7 streams, continuous or daily stage for 61 streams, periodic stage for 0 streams; peak stage and discharge for 0 streams; continuous or daily elevations for 10 lakes, periodic elevations for 20 lakes; continuous ground water levels for 53 wells, periodic ground-water levels for 589 wells; quality-of-water data for 44 surface-water sites and 86 wells. These data represent the National Water Data System records collected by the U.S. Geological Survey and cooperating local, State and Federal agencies in Florida.

Water Data Report↗
USGS2005

Water resources data, Florida, water year 2004, Volume 1B: northeast Florida ground water

Water resources data for the 2004 water year in Florida consist of continuous or daily discharge for 405 streams, periodic discharge for 12 streams, continuous or daily stage for 159 streams, periodic stage for 19 streams, peak stage and discharge for 30 streams; continuous or daily elevations for 14 lakes, periodic elevations for 23 lakes; continuous ground-water levels for 408 wells, periodic ground-water levels for 1,157 wells; quality-of-water data for 140 surface-water sites and 239 wells. The data for northeast Florida include continuous or daily discharge for 140 streams, periodic discharge for 4 streams, continuous or daily stage for 58 streams, periodic stage for 3 streams; peak stage and discharge for 0 streams; continuous or daily elevations for 10 lakes, periodic elevations for 20 lakes; continuous ground water levels for 50 wells, periodic ground-water levels for 522 wells; quality-of-water data for 40 surface-water sites and 66 wells. These data represent the National Water Data System records collected by the U.S. Geological Survey and cooperating local, State and Federal agencies in Florida.

Water Data Report↗
USGS1986

Water resources data, Florida, water year 1985. Volume 3B: Southwest Florida ground water

Water resources data for the 1985 water year in Florida consist of continuous or daily discharge for 285 streams, periodic discharge for 38 streams, miscellaneous discharge 1 for 110 streams, continuous or daily stage for 124 streams, periodic stage for 32 streams, peak discharge for 98 streams and peak stage for 87 streams; continuous or daily elevations for 89 lakes, periodic elevations for 82 lakes; continuous ground-water levels for 473 wells, periodic ground-water levels for 550 wells, and miscellaneous water-level measurements for 2,588 wells; quality-of-water data for 239 surface-water sites and 699 wells. The data for southwest Florida include continuous or daily discharge for 91 streams, periodic discharge for 23 streams, miscellaneous discharge for 57 streams, peak discharge for 20 streams, continuous or daily stage for 30 streams; continuous elevations for 50 lakes and periodic elevations for 39 lakes; continuous ground-water levels for 223 wells, periodic ground-water levels for 146 wells, and miscellaneous water-level measurements for 1,477 wells; quality of water for 146 surface-water sites and 287 wells. These data represent the National Water Data System records collected by the U. S. Geological Survey and cooperating local, state and federal agencies in Florida

Florida↗
USGS1988

Water resources data for Florida, water year 1987. Volume 2B. South Florida ground water

Water resources data for the 1987 water year in Florida consists of continuous or daily discharge for 320 streams, periodic discharge for 38 streams, miscellaneous discharge for 29 streams, continuous or daily stage for 94 streams, periodic stage for 48 streams, peak discharge for 76 streams and peak stage for 69 streams; continuous or daily elevations for 80 lakes, periodic elevations for 74 lakes; continuous ground-water levels for 477 wells, periodic ground-water levels for 562 wells, and miscellaneous water level measurements for 2,886 wells; quality of water data for 223 surface-water sites and 900 wells. The data for South Florida include continuous or daily discharge for 47 streams, periodic discharge for 2 streams, peak discharge for 4 streams, continuous or daily stage for 63 streams, periodic stage for 16,streams, peak discharge for 3 streams, and peak stage for 12 streams; continuous elevations for 1 lake, and periodic elevations for 5 lakes; continuous ground-water levels for 169 wells, periodic ground-water levels for 213 wells, and miscellaneous water-level measurements for 388 wells; quality-of-water for 10 surface-water sites and 521 wells. This data represent the National Water Data System records collected by the U.S. Geological Survey and cooperation local, state and federal agencies in Florida.

Florida↗
USGS1989

Water resources data, Florida, water year 1988. Volume 2B: South Florida - ground water

Water resources data for the 1988 water year in Florida consists of continuous or daily discharge for 338 streams, periodic discharge for 34 streams, miscellaneous discharge for 28 streams, continuous or daily stage for 152 streams, periodic stage for 29 streams, peak discharge for 71 streams, continuous daily tide stage for 8 streams, and peak stage for 84 streams; continuous or daily elevations for 73 lakes, periodic elevations for 72 lakes; continuous ground-water levels for 490 wells, periodic ground-water levels for 1620 wells, and miscellaneous water level measurements for 2678 wells; quality of water data for 158 surface-water sites and 884 wells. The data for South Florida include continuous or daily discharge for 65 streams, periodic discharge for 2 streams, peak discharge for 4 streams, continuous or daily stage for 82 streams, periodic stage for 16 streams, peak discharge for 2 streams, and peak stage for 12 streams; continuous elevations for 1 lake, and periodic elevations for 5 lakes; continuous ground-water levels for 179 wells, period ground-water levels for 298 wells, and miscellaneous water-level measurements for 250 wells; quality-of-water for 6 surface-water sites and 558 wells. This data represent the National Water Data System ·records collected by the U.S. Geological Survey and cooperation local, state and federal agencies in Florida.

Florida↗
USGS2001

Simulated ground-water flow and water quality of the Mississippi River alluvium near Burlington, Iowa, 1999

The City of Burlington, Iowa, obtains some of its public water supply by withdrawing ground water from the Mississippi River alluvium, an alluvial aquifer adjacent to the Mississippi River. The U.S. Geological Survey, in cooperation with the City of Burlington, conducted a hydrologic study of the Mississippi River alluvium near Burlington in 1999 to improve understanding of the flow system, evaluate the effects of hypothetical pumping scenarios on the flow system, and evaluate selected water-quality constituents in parts of the alluvium. A steady-state, ground-water flow model was constructed for a 7-square-mile area of the alluvium using October 1999 hydrologic conditions to help conceptualize the flow system, identify sources of water to the alluvium, and assess potential effects from additional hypothetical ground-water withdrawals from the lower alluvium. The model was discretized into a 70-row by 68-column grid using cells measuring 200 feet by 200 feet. Three model layers were used to represent flow in the upper part of the alluvium, lower part of the alluvium, and bedrock. The primary sources of ground water to the alluvium were subsurface flow from areas of the alluvium adjacent to the modeled area, recharge from precipitation, subsurface flow from Flint River streamchannel deposits adjacent to the alluvium, and river leakage. The primary components of outflow from the flow system were river leakage, municipal ground-water withdrawals (pumpage), and leakage to drainage ditches. Three hypothetical pumping scenarios were used to assess the potential effects of increased ground-water withdrawals from the lower part of the alluvium: (1) pumping a second existing municipal well at a rate of 0.5 million gallons per day, (2) pumping a hypothetical well completed in an area between the city water-treatment facility and Flint River at a rate of 1.0 million gallons per day, and (3) pumping a hypothetical well completed in an area south of the Flint River at a rate of 1.0 million gallons per day. Maximum additional simulated drawdown in the upper alluvium ranged from less than 3 feet (for scenario 1) to about 9 feet (for scenario 3). Maximum additional simulated drawdown in the lower alluvium ranged from about 12 feet (for scenario 1) to about 34 feet (for scenario 3). Water budgets for each scenario indicated future additional withdrawals from the flow system near Burlington’s existing municipal wells would significantly increase the amount of river leakage into the flow system. Water samples collected from the alluvium indicated ground water can be classified as a calcium-magnesium-bicarbonate type. Reducing conditions likely occur in some localized areas of the alluvium, as suggested by relatively large concentrations of dissolved iron (4,390 micrograms per liter) and manganese (2, 430 micrograms per liter) in some ground-water samples. Nitrite plus nitrate was detected at concentrations greater than or equal to 8 milligrams per liter in three samples collected from observation wells completed in close proximity to cropland; the nitrite plus nitrate concentration in one groundwater sample exceeded the U.S. Environmental Protection Agency Maximum Contaminant Level for nitrate in drinking water (10 milligrams per liter as N). Triazine herbicides (atrazine, cyanazine, propazine, simazine, and selected degradation products) and chloroacetanilide herbicides (acetochlor, alachlor, and metolachlor) were detected in some water samples. A greater number of herbicide compounds were detected in surface-water samples than in ground-water samples. Herbicide concentrations typically were at least an order of magnitude greater in surfacewater samples than in ground-water samples. The Maximum Contaminant Level for alachlor (2 micrograms per liter) was exceeded in a sample from Dry Branch Creek at Tama Road and for atrazine (3 micrograms per liter) was exceeded in samples collected from Dry Branch Creek at Tama Road and the county drainage ditch at Tama Road.

Iowa↗
USGS2005

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

During 1997, the Dougherty County Health Department sampled more than 700 wells completed in the Upper Floridan aquifer in Dougherty County, Georgia, and determined that nitrate as nitrogen (hereinafter called nitrate) concentrations were above 10 milligrams per liter (mg/L) in 12 percent of the wells. Ten mg/L is the Georgia primary drinking-water standard. The ground-water flow system is complex and poorly understood in this predominantly agricultural area. Therefore, the U.S. Geological Survey (USGS) - in cooperation with Albany Water, Gas and Light Commission - conducted a study to better define ground-water flow and water quality in the Upper Florida aquifer in the southwestern Albany area, Georgia. Ground-water levels were measured in the southwestern Albany area, Georgia, during May 1998 and March 1999 (spring), and October 1998 and September 1999 (fall). Groundwater levels measured in 75 wells open only to the Upper Floridan aquifer were used to construct potentiometric-surface maps for those four time periods. These maps show that ground water generally flows from northwest to southeast at gradients ranging from about 2 to greater than 10 feet per mile. During spring and fall 1998, ground-water levels were high and mounding of the potentiometric surface occurred in the central part of the study area, indicating a local recharge area. Water levels declined from December through February, and by March 1999 the mound in the potentiometric surface had dissipated. Of the 75 wells in the potentiometric network, 24 were selected for a water-quality network. These 24 wells and 1 spring were sampled during fall 1998 and spring 1999. Samples were analyzed for major chemical constituents, selected minor constituents, selected nutrients, and chlorofluorocarbons (CFC). Water-quality field measurements - such as water temperature, pH, specific conductance (SC), and dissolved oxygen (DO) - were taken at each well. During August 2000, a ground-water sample was collected and analyzed for selected sewage tracers. During March 2001, water samples from selected wells were analyzed for nitrogen and oxygen isotopes. Age-dating analysis using CFCs yield apparent groundwater ages that range from modern to greater than 50 years. The chemistry of ground water in the Upper Floridan aquifer varies widely throughout the southwestern Albany area, Georgia, and in general represents the chemistry commonly found in recharge areas. From fall 1998 through spring 1999, median values of pH, SC, and DO concentration were 7.6 standard units, 266 microsiemens per centimeter at 25 degrees Celsius (uS/cm), and 5.6 mg/L, respectively. The SC is highest (350 - 400 uS/cm) where mounding of the potentiometric surface exists. Specific DO concentrations indicate an area of anoxic ground water in the north-central part of the study area. Water samples indicate that ground water in the study area is dominated by calcium and bicarbonate ions, which is consistent with the limestone lithology of the aquifer. About 25 percent of the samples contained sodium and chloride at ratios similar to those in rainfall, indicating a close proximity to recharge areas. The remaining water samples, however, had sodiumchloride ratios less than 0.90, the ratio in Tift County, Georgia, rainfall samples. These low sodium-chloride ratios are consistent with chloride enrichment. Minor constituent and nutrient concentrations typically are below laboratory reporting limits; however, the maximum nitrate concentration measured during the study period was 12.2 mg/L, and the median concentration for the study period was 3.0 mg/L. Samples collected during 1999 had a higher median nitrate concentration than the 1998 samples. Regression analysis indicated that nitrate concentrations are related exponentially to chloride concentrations. Four distinct groups of ground-water-quality samples, plus four unique samples, were identified using cluster analysis. Water-quality groups I and

Georgia↗
USGS2014

Suggestions as to future research in ground‐water hydrology

Determination of the ground‐water supply available from any aquifer or in any specified area requires not merely the application of specific quantitative methods but also a broad and accurate knowledge of the geologic, hydrologlc, and geochemical factors that are involved, and consideration of the economic and legal limitations. Further research is needed as to geologic texture and structure in relation to the occurrence and movement of the water; the precise nature of specific yield, which determines the effective storage capacities of the aquifers; the molecular physics involved in the downward and upward movement of water in the zone of aeration, and quantitative evaluation of ground‐water recharge and discharge; the hydraulics of ground water, as studied by pumping test methods, with special reference to boundary conditions; studies of perennial yield of aquifers of low permeability; the genesis of the mineral contents of ground water as determined through appropriate geologic, hydrologlc, and chemical studies; and methods of geophysical exploration and well logging for determining the occurrence of ground water. Serious study is also needed as to practicable methods of implementing the recently developed principles and methods of ground‐water hydrology in the production of water supplies and the economic and legal problems involved.

Eos, Transactions, American Geophysical Union↗
USGS2005

Simulating reservoir leakage in ground-water models

Leakage to ground water resulting from the expansion and contraction of reservoirs cannot be easily simulated by most ground-water flow models. An algorithm, entitled the Reservoir Package, was developed for the United States Geological Survey (USGS) three-dimensional finite-difference modular ground-water flow model MODFLOW. The Reservoir Package automates the process of specifying head-dependent boundary cells, eliminating the need to divide a simulation into many stress periods while improving accuracy in simulating changes in ground-water levels resulting from transient reservoir stage. Leakage between the reservoir and the underlying aquifer is simulated for each model cell corrresponding to the inundated area by multiplying the head difference between the reservoir and the aquifer with the hydraulic conductance of the reservoir-bed sediments.

Groundwater↗