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Evaluation of hydrologic properties of the Long Island ground-water reservoir using cross-sectional electric-analog models

Variables necessary for constructing a quantitative model to predict the response of ground-water reservoirs to hydrologic stresses are in four classes: (a) external and internal geometry of the reservoir, (b) nature of the reservoir boundaries, (c) areal distribution of horizontal and vertical hydraulic conductivities, and (d) areal distribution of storage capability within the reservoir. In this report, the sensitivity of the Long Island ground-water reservoir's reponse to the first three of these variables was evaluated using analog models.

New York↗

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↗

Base-flow characteristics of streams in the Valley and Ridge, Blue Ridge, and Piedmont physiographic provinces of Virginia

Growth within the Valley and Ridge, Blue Ridge, and Piedmont Physiographic Provinces of Virginia has focused concern about allocation of surface-water flow and increased demands on the ground-water resources. The purpose of this report is to (1) describe the base-flow characteristics of streams, (2) identify regional differences in these flow characteristics, and (3) describe, if possible, the potential surface-water and ground-water yields of basins on the basis of the base-flow characteristics. Base-flow characteristics are presented for streams in the Valley and Ridge, Blue Ridge, and Piedmont Physiographic Provinces of Virginia. The provinces are separated into five regions: (1) Valley and Ridge, (2) Blue Ridge, (3) Piedmont/Blue Ridge transition, (4) Piedmont northern, and (5) Piedmont southern. Different flow statistics, which represent streamflows predominantly comprised of base flow, were determined for 217 continuous-record streamflow-gaging stations from historical mean daily discharge and for 192 partial-record streamflow-gaging stations by means of correlation of discharge measurements. Variability of base flow is represented by a duration ratio developed during this investigation. Effective recharge rates were also calculated. Median values for the different flow statistics range from 0.05 cubic foot per second per square mile for the 90-percent discharge on the streamflow-duration curve to 0.61 cubic foot per second per square mile for mean base flow. An excellent estimator of mean base flow for the Piedmont/Blue Ridge transition region and Piedmont southern region is the 50-percent discharge on the streamflow-duration curve, but tends to underestimate mean base flow for the remaining regions. The base-flow variability index ranges from 0.07 to 2.27, with a median value of 0.55. Effective recharge rates range from 0.07 to 33.07 inches per year, with a median value of 8.32 inches per year. Differences in the base-flow characteristics exist between regions. The median discharges for the Valley and Ridge, Blue Ridge, and Piedmont/Blue Ridge transition regions are higher than those for the Piedmont regions. Results from statistical analysis indicate that the regions can be ranked in terms of base-flow characteristics from highest to lowest as follows: (1) Piedmont/Blue Ridge transition, (2) Valley and Ridge and Blue Ridge, (3) Piedmont southern, and (4) Piedmont northern. The flow statistics are consistently higher and the values for base-flow variability are lower for basins within the Piedmont/Blue Ridge transition region relative to those from the other regions, whereas the basins within the Piedmont northern region show the opposite pattern. The group rankings of the base-flow characteristics were used to designate the potential surface-water yield for the regions. In addition, an approach developed for this investigation assigns a rank for potential surface-water yield to a basin according to the quartiles in which the values for the base-flow characteristics are located. Both procedures indicate that the Valley and Ridge, Blue Ridge, and Piedmont/Blue Ridge transition regions have moderate-to-high potential surface-water yield and the Piedmont regions have low-to-moderate potential surface-water yield. In order to indicate potential ground-water yield from base-flow characteristics, aquifer properties for 51 streamflow-gaging stations with continuous record of streamflow data were determined by methods that use streamflow records and basin characteristics. Areal diffusivity ranges from 17,100 to 88,400 feet squared per day, with a median value of 38,400 feet squared per day. Areal transmissivity ranges from 63 to 830 feet squared per day, with a median value of 270 feet squared per day. Storage coefficients, which were estimated by dividing areal transmissivity by areal diffusivity, range from approximately 0.001 to 0.019 (dimensionless), with a median value of 0.007. The median value for areal diffusivity decreases as potential surface-water yield of the basins increases. The ranking of areal diffusivity does not correspond with the ranking of poten tial surface-water yield for either the regions or the basins. Areal transmissivity generally increases as storage coefficient increases; how ever, basins with low potential surface-water yield generally have high values of areal trans missivity associated with low values of storage coefficient over a narrow range relative to those from basins designated as having moderate-to- high potential surface-water yield. Although the basins with high potential surface-water yield tend to have comparatively lower values for areal transmissivity, storage coefficients gener ally are large when compared to those from basins with similar values of areal transmissivity but different potential surface-water yield. Aquifer properties were grouped by potential surface-water yield and were related to hydrogeologic units categorized by large, medium, and small well yields for the Valley and Ridge Physiographic Province and for the Blue Ridge and Piedmont Physiographic Provinces. Generally, no trend is evident between areal diffusivity and the hydrogeologic units. Some of the high val-ues of areal diffusivity are associated with basins predominantly underlain by hydrogeologic units with small well yields, especially basins with a low potential surface-water yield. Areal transmissivity and storage coefficient tend to decrease, which is the expected trend, as more of the basin is underlain by the hydrogeologic unit with small well yields in the Valley and Ridge Physiographic Province. A similar trend is indi-cated for the hydrogeologic unit with medium well yields in the Blue Ridge and Piedmont Physiographic Provinces. Areal transmissivity and storage coefficient tend to increase, which is not the expected trend, as more of the basin is underlain by the hydrogeologic unit with small well yields in the Blue Ridge and Piedmont Physiographic Provinces. The base-flow characteristics of a basin may provide a relative indication of the potential ground-water yield; but other factors need to be considered, such as geologic structure, lithology, precipitation, relief, and the degree of hydraulic interconnection between the regolith and bedrock.

Virginia↗

Water-quality data from a landfill, Pinellas County, Florida, May 1975-October 1977

Ground water in and near a proposed landfill site can become contaminated by leachates from the fill material. Realizing that potential, Pinellas County entered into a cooperative investigation with the U.S. Geological Survey to determine background water-quality conditions, and to evaluate the potential effects of landfill leachate on the quality of ground water at a landfill site in Pinellas County (fig. 1). The investigation started in May 1975 and landfill operation began in November 1975. The purpose of this report is to make available well records, logs of wells, and surface- and ground-water quality data for planning purposes, and to provide basic data for a subsequent interpretive report. From May 1975 to October 1977, surface- and ground-water samples were collected periodically to obtain information on certain background water-quality conditions at the landfill site. Specific conductance and pH were determined in the field. Sodium, potassium, calcium, magnesium, chloride, trace metals, chemical and biochemical oxygen demands, coliform, select herbicides and pesticides, and nitrogen and phosphorus species were determined in the laboratory.

Florida↗

Hydrologic budgets of regional aquifer systems of the United States for predevelopment and development conditions

Ground-water budgets are presented in this report for 14 regionally extensive aquifer systems; pumpage from 11 of these systems provided from 40 to 50 percent of the ground water withdrawn in the United States during the 1970's and 1980's. The budgets are based on simulation results from computer-based models developed as part of the Regional Aquifer-System Analysis Program of the U.S. Geological Survey. Most of the models cover large areas (30,000-300,000 square miles) and generally are constructed with coarse-mesh finite-difference grids designed to simulate regional ground-water flow. The groundwater budgets derived from these models generally do not include local flow that enters and exits regional aquifers after traveling only a few miles or flow in overlying surficial aquifers. Budgets are presented for predevelopment and recent pumping conditions for most of the aquifer systems.

Professional Paper↗

Ground-water conditions in the east shore area, Box Elder, Davis, and Weber Counties, Utah 1960-69

This report is one of a series that is prepared by the U.S. Geological Survey in cooperation with the Utah Department of Natural Resources, Division of Water Rights, which describes water resources in selected areas in Utah. The period of study on which this report was based was from July 1968 to March 1970, but the period of record covered by the report is from 1960 to 1969. The purposes of this study were to determine changes in ground-water development in the East Shore area and to determine the effects of those changes on the ground-water system since the area was last studied (Smith and Gates, 1963). The study was also made to obtain additional information to guide further development of ground water in the area, in order to meet growing needs for municipal, industrial, and agriculture water supplies.

Utah↗

Methods and Indicators for Assessment of Regional Ground-Water Conditions in the Southwestern United States

Monitoring the status and trends in the availability of the Nation's ground-water supplies is important to scientists, planners, water managers, and the general public. This is especially true in the semiarid to arid southwestern United States where rapid population growth and limited surface-water resources have led to increased use of ground-water supplies and water-level declines of several hundred feet in many aquifers. Individual well observations may only represent aquifer conditions in a limited area, and wells may be screened over single or multiple aquifers, further complicating single-well interpretations. Additionally, changes in ground-water conditions may involve time scales ranging from days to many decades, depending on the timing of recharge, soil and aquifer properties, and depth to the water table. The lack of an easily identifiable ground-water property indicative of current conditions, combined with differing time scales of water-level changes, makes the presentation of ground-water conditions a difficult task, particularly on a regional basis. One approach is to spatially present several indicators of ground-water conditions that address different time scales and attributes of the aquifer systems. This report describes several methods and indicators for presenting differing aspects of ground-water conditions using water-level observations in existing data-sets. The indicators of ground-water conditions developed in this study include areas experiencing water-level decline and water-level rise, recent trends in ground-water levels, and current depth to ground water. The computer programs written to create these indicators of ground-water conditions and display them in an interactive geographic information systems (GIS) format are explained and results illustrated through analyses of ground-water conditions for selected alluvial basins in the Lower Colorado River Basin in Arizona.

Scientific Investigations Report↗

MODFLOW-2000, the U.S. Geological Survey Modular Ground-Water Model -Documentation of the Hydrogeologic-Unit Flow (HUF) Package

This report documents the Hydrogeologic-Unit Flow (HUF) Package for the groundwater modeling computer program MODFLOW-2000. The HUF Package is an alternative internal flow package that allows the vertical geometry of the system hydrogeology to be defined explicitly within the model using hydrogeologic units that can be different than the definition of the model layers. The HUF Package works with all the processes of MODFLOW-2000. For the Ground-Water Flow Process, the HUF Package calculates effective hydraulic properties for the model layers based on the hydraulic properties of the hydrogeologic units, which are defined by the user using parameters. The hydraulic properties are used to calculate the conductance coefficients and other terms needed to solve the ground-water flow equation. The sensitivity of the model to the parameters defined within the HUF Package input file can be calculated using the Sensitivity Process, using observations defined with the Observation Process. Optimal values of the parameters can be estimated by using the Parameter-Estimation Process. The HUF Package is nearly identical to the Layer-Property Flow (LPF) Package, the major difference being the definition of the vertical geometry of the system hydrogeology. Use of the HUF Package is illustrated in two test cases, which also serve to verify the performance of the package by showing that the Parameter-Estimation Process produces the true parameter values when exact observations are used.

Open-File Report↗

Application of a Geographic Information System for regridding a ground-water flow model of the Columbia Plateau Regional Aquifer System, Walla Walla River basin, Oregon-Washington

Computerized Geographic Information Systems (GIS) have become viable and valuable tools for managing,analyzing, creating, and displaying data for three-dimensional finite-difference ground-water flow models. Three GIS applications demonstrated in this study are: (1) regridding of data arrays from an existing large-area, low resolution ground-water model to a smaller, high resolution grid; (2) use of GIS techniques for assembly of data-input arrays for a ground-water model; and (3) use of GIS for rapid display of data for verification, for checking of ground-water model output, and for the cre.ation of customized maps for use in reports. The Walla Walla River Basin was selected as the location for the demonstration because (1) data from a low resolution ground-water model (Columbia Plateau Regional Aquifer System Analysis [RASA]) were available and (2) concern for long-term use of water resources for irrigation in the basin. The principal advantage of regridding is that it may provide the ability to more precisely calibrate a model, assuming chat a more detailed coverage of data is available, and to evaluate the numerical errors associated with a particular grid design.Regridding gave about an 8-fold increase in grid-node density.Several FORTRAN programs were developed to load the regridded ground-water data into a finite-difference modular model as model-compatible input files for use in a steady-state model run.To facilitate the checking and validating of the GIS regridding process, maps and tabular reports were produced for each of eight ground-water parameters by model layer. Also, an automated subroutine that was developed to view the model-calculated water levels in cross-section will aid in the synthesis and interpretation of model results.

Water-Resources Investigations Report↗

Regional Aquifer-System Analysis Program of the U.S. Geological Survey, 1978-1992

The major ground-water systems of the United States have been investigated by the U.S. Geological Survey (USGS) through its Regional Aquifer-System Analysis (RASA) Program. During the first 15 years of the program (1978-92), 25 regional aquifer systems, including the most heavily pumped aquifers in the Nation, were intensively studied. As of mid-1992, 18 of the regional aquifer studies are completed or nearly so; 7 of the regional aquifer studies are ongoing, and compilation of a national ground-water atlas is in progress. This report summarizes the status of each RASA study and briefly describes the hydrology of the 25 regional aquifer systems. Important study results and examples of applications of study results are presented for some of the completed RASA investigations. The major contributions of the RASA Program are (1) assembly of data from numerous local studies and long-time data collections into systematic regional data bases; (2) comprehensive descriptions of the geologic, hydrologic, and geochemical characteristics of the regional aquifer systems; and (3) an understanding of how the regional ground-water-flow systems function under natural (predevelopment) and current (developed) conditions. To provide the comprehensive system descriptions, many of the RASA studies present, for the first time, maps depicting the hydrogeologic frameworks, water chemistry, potentiometric surfaces, and other aspects of entire regional aquifer systems. To provide an understanding of how the flow systems function, several of the completed RASA studies provide, for the first time, hydrologic budgets for both predevelopment and developed conditions. The results of the RASA Program are contained in nearly 900 reports published by the USGS, as well as various State and local agencies, and in articles published in scientific journals. A series of U.S. Geological Survey Professional Papers are being published to summarize and synthesize the results of each RASA study.

Circular↗

Quality of ground water in Webb County, Texas, 1997-98

Rapid development and population growth are occurring in Webb County in south Texas (fig. 1). Water managers need information on the ground-water resources of the area to address the increased demand for water caused by the development. To help meet this need, the U.S. Geological Survey (USGS), in cooperation with the City of Laredo, began a study in 1997 to assess the ground-water resources of the county. This report describes the quality of ground water determined from water samples collected during 1997-98.

Fact Sheet↗

Ground-water sampling, analytical results, and water-level measurements at sites FT03, LF13, and WP14/LF15, East Management Unit, Dover Air Force Base, Delaware, January-October 2000

The U.S. Geological Survey, in cooperation with the U.S. Air Force, collected ground-water samples and made water-level measurements from January through October 2000 to monitor natural attenuation at four sites in the East Management Unit of Dover Air Force Base in Kent County, Delaware. The information in this report is based on data from ground-water samples collected during two sampling events, which occurred from January through March 2000 and September through October 2000. Ground-water samples and water-level measurements were collected from 36 monitor wells during the first sampling event. During the second sampling event, groundwater samples were collected from 34 monitor wells and water-level measurements were made in 29 monitor wells. Water-level measurements were also made in 103 wells during a synoptic in March 2000. The analytical results from the groundwater samples, the water-level measurements, and data-collection techniques are presented in this report. Analytical results indicate that the U.S. Environmental Protection Agency's maximum contaminant levels for constituents analyzed were exceeded in 10 samples collected during the first sampling event and 11 samples collected during the second sampling event. An independent quality-assurance data validation indicated that the water-quality data collected during this study were of good quality, reproducible, and unbiased.

Delaware↗

Completion reports, core logs, and hydrogeologic data from wells and piezometers in Prospect Gulch, San Juan County, Colorado

In the late nineteenth century, San Juan County, Colorado, was the center of a metal mining boom in the San Juan Mountains. Although most mining activity ceased by the 1990s, the effects of historical mining continue to contribute metals to ground water and surface water. Previous research by the U.S. Geological Survey identified ground-water discharge as a significant pathway for the loading of metals to surface water from both acid-mine drainage and acid-rock drainage. In an effort to understand the ground-water flow system in the upper Animas River watershed, Prospect Gulch was selected for further study because of the amount of previous data provided in and around that particular watershed. In support of this ground-water research effort, wells and piezometers were installed to allow for coring during installation, subsurface hydrologic testing, and the monitoring of ground-water hydraulic heads and geochemistry. This report summarizes the data that were collected during and after the installation of these wells and piezometers and includes (1) subsurface completion details, (2) locations and elevations, (3) geologic logs and elemental data, (4) slug test data for the estimation of subsurface hydraulic conductives, and (5) hydraulic head data.

Open-File Report↗

Retrospective Review of Watershed Characteristics and a Framework for Future Research in the Sarasota Bay Watershed, Florida

The U.S. Geological Survey, in cooperation with the Sarasota Bay Estuary Program conducted a retrospective review of characteristics of the Sarasota Bay watershed in west-central Florida. This report describes watershed characteristics, surface- and ground-water processes, and the environmental setting of the Sarasota Bay watershed. Population growth during the last 50 years is transforming the Sarasota Bay watershed from rural and agriculture to urban and suburban. The transition has resulted in land-use changes that influence surface- and ground-water processes in the watershed. Increased impervious cover decreases recharge to ground water and increases overland runoff and the pollutants carried in the runoff. Soil compaction resulting from agriculture, construction, and recreation activities also decreases recharge to ground water. Conventional approaches to stormwater runoff have involved conveyances and large storage areas. Low-impact development approaches, designed to provide recharge near the precipitation point-of-contact, are being used increasingly in the watershed. Simple pollutant loading models applied to the Sarasota Bay watershed have focused on large-scale processes and pollutant loads determined from empirical values and mean event concentrations. Complex watershed models and more intensive data-collection programs can provide the level of information needed to quantify (1) the effects of lot-scale land practices on runoff, storage, and ground-water recharge, (2) dry and wet season flux of nutrients through atmospheric deposition, (3) changes in partitioning of water and contaminants as urbanization alters predevelopment rainfall-runoff relations, and (4) linkages between watershed models and lot-scale models to evaluate the effect of small-scale changes over the entire Sarasota Bay watershed. As urbanization in the Sarasota Bay watershed continues, focused research on water-resources issues can provide information needed by water-resources managers to ensure the future health of the watershed.

Open-File Report↗

Chemical Analyses of Ground Water in the Carson Desert near Stillwater, Churchill County, Nevada, 2005

This report presents the chemical analyses of ground-water samples collected in 2005 from domestic wells located in the Stillwater area of the Carson Desert (fig. 1). These data were evaluated for evidence of mixing with nearby geothermal waters (Fosbury, 2007). That study used several methods to identify mixing zones of ground and geothermal waters using trace elements, chemical equilibria, water temperature, geothermometer estimates, and statistical techniques. In some regions, geothermal sources influence the chemical quality of ground water used for drinking water supplies. Typical geothermal contaminants include arsenic, mercury, antimony, selenium, thallium, boron, lithium, and fluoride (Webster and Nordstrom, 2003). The Environmental Protection Agency has established primary drinking water standards for these, with the exception of boron and lithium. Concentrations of some trace metals in geothermal water may exceed drinking water standards by several orders of magnitude. Geothermal influences on water quality are likely to be localized, depending on directions of ground water flow, the relative volumes of geothermal sources and ground water originating from other sources, and depth below the surface from which water is withdrawn. It is important to understand the areal extent of shallow mixing of geothermal water because it may have adverse chemical and aesthetic effects on domestic drinking water. It would be useful to understand the areal extent of these effects.

Open-File Report↗

Resistivity sections, upper Arkansas River basin, Colorado

A reconnaissance investigation of ground-water resources in the upper Arkansas River basin from Pueblo to Leadville is being made by the U.S. Geological Survey in cooperation with the Southeastern Colorado Water Conservancy District, and the Colorado Division of Water Resources, Colorado State Engineer. As part of the investigation, surface geophysical electrical resistivity surveys were made during the summer and fall of 1970 near Buena Vista and Westcliffe, Colo. (p1.1). The resistivity surveys were made to verify a previous gravity survey and to help locate areas where ground-water supplies might be developed. This report presents the results of the surveys in the form of two resistivity sections.

Colorado↗

A compilation of hydrologic data before and during highway construction in parts of Tijeras Canyon, New Mexico, 1972-1978

Tijeras Canyon extends about 15 miles eastward from the eastern edge of Albuquerque, NM. The canyon is the site of a new part of Interstate Highway 40. The purpose of this report is to present surface- and ground-water data collected prior to and during highway construction. Well and spring data from near the construction site are tabulated, and spring inflow in Tijeras Creek is shown. Water levels in selected wells are shown in hydrographs based on monthly measurements and continuous water level measurements. This report includes all of the data in a similar previous report (U.S. Geological Survey Open-file report 78-238), plus approximately one additional year of data. (USGS).

Open-File Report↗

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

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

Open-File Report↗