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The U.S. Geological Survey's National Water-Quality Assessment program includes extensive data- collection efforts to assess the quality of the Nations's streams. These studies require analyses of stream samples for major ions, nutrients, sediments, and organic contaminants. For the information to be comparable among studies in different parts of the Nation,...

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;...

The map area is in the Mangala-Memnonia region (fig. 1), which contains remarkably diverse geologic features and terrain types. Studies of the Mariner...

The geologic units in the vicinity of a hazardous- waste landfill near Pinewood, S.C., were divided into hydrogeologic units on the basis of lithologic and hydrologic characteristics. A quasi-3- dimensional finite-difference ground-water-flow model was constructed to represent the hydrogeologic flamework. The simulation results indicate that if non-reactive constituents were released...

The U.S. Geological Survey computer model to simulate two-dimensional solute transport and dispersion in ground water (Konikow and Bredehoeft, 1978; Goode and Konikow, 1989) has been modified to improve management of input and output data and to provide progressive run-time information. All opening and closing of files are now done...

Undersea transmission lines and shoreline AC-DC conversion stations and near-shore transmission lines are being considered as part of a system for transporting energy between the Hawaiian Islands. These facilities will need to be designed so that they will not be damaged or destroyed by coastal or undersea landslides. Advanced site...

Ground-water capture zone boundaries for individual pumped wells in a confined aquffer were delineated by using groundwater models. Both analytical and numerical (semi-analytical) models that more accurately represent the $round-water-flow system were used. All models delineated 2-dimensional boundaries (capture zones) that represent the areal extent of groundwater contribution to a...

Nutrient and organic compound data from the U.S. Geological Survey and the U.S. Environmental Protection Agency STORET data bases provided information for development of a preliminary conceptual model of spatial and temporal ground-water quality in the upper Snake River Basin. Nitrite plus nitrate (as nitrogen; hereafter referred to as nitrate)...

Rainfall-runoff data from three watersheds were selected for calibration and verification of the U.S. Geological Survey's Distributed Routing Rainfall-Runoff Model. The watersheds chosen are residentially developed. The conceptually based model uses an optimization process that adjusts selected parameters to achieve the best fit between measured and simulated runoff volumes and...

The Precipitation-Runoff Modeling System (PRMS) model of the U.S. Geological Survey was used to simulate the hydrologic effects of timber management in 11 small, upland drainage basins of the Coast Range in Oregon. The coefficients of determination for observed and simulated daily flow during the calibration periods ranged from 0.92...

In the winter of 1811-12, three of the largest historic earthquakes in the United States occurred near New Madrid, Missouri. Seismicity continues to the present day throughout a tightly clustered patter of epicenters centered on the bootheel of Missouri, including parts of northeastern Arkansas, northwestern Tennessee, western Kentucky, and southern...

Ground water is the sole freshwater supply for the Eastern Shore Peninsula in Virginia. The fresh ground-water-flow system consists of a water-table aquifer underlain by three confined aquifers separated by intervening confining units. Results of simulations using a sharp-interface, ground-water-flow model indicate that current levels of withdrawal have not caused...

The flow-routing module of the Hydrologic Simulation Program-Fortran watershed model was calibrated for 31 reaches on the Delaware River and 5 of it principal tributaries. These calibrations primarily involved the development of discharge-storage volume relations for the defined reaches. Daily discharge records for stream-gaging stations located at the upstream ends...

No abstract available....

Rapid population growth in Carson Valley, west- central Nevada, requires a dependable municipal water source. Artificial recharge of aquifers using available flow of the Carson River is one way to increase the amount of water in underground storage and maintain a dependable ground-water supply. Ground water can be artificially recharged...

These maps describe the sediments and sedimentary environment of the southwestern Puerto Rico shelf (index). In addition to presenting new data, the maps summarize earlier geological investigations. There are two morphological zones separated along a line extending southward from Punta Jorobaflo. The Parguera shelf extends from this line to the...

Geohydrologic data and a ground-water flow model were used to calculate a water budget and evaluate the contribution of regional groundwater flow to on-farm drainflow in a part of the western San Joaquin Valley, California. Regional ground-water flow is affected by the distribution of unconsolidated coarse- and fine-grained sediment. Predominantly...

This report presents the results of a study by the U.S. Geological Survey, in cooperation with the Virginia Department of Environmental Quality-- Division of Intergovernmental Coordination to monitor and estimate loads of selected nutrients and suspended solids discharged to Chesapeake Bay from two major tributaries in Virginia. From July 1988...

The Minnesota Management Systems Evaluation Area project is part of a multi-scale, inter-agency initiative to evaluate the effects of agricultural management systems on water quality in the midwest corn belt. The research area is located in the Anoka Sand Plain about 5 kilometers southwest of Princeton, Minnesota. The ground-water-quality monitoring...

The report presents techniques used for estimating 7-day 2-year (7Q2) and 7-day 10-year (7Q10) flows at continuous-record streamflow-gaging stations, partial-record stations, and ungaged sites on streams in Massachusetts. A two-parameter log-normal probability distribution was used to compute low flows at 31 continuous-record stream-flow-gaging stations. Graphical and mathematical techniques were used...

A multiple-regression methodology was used to help answer questions concerning model reliability, and to calibrate a time-dependent variable-density ground-water flow model of the gulf coast aquifer systems in the south-central United States. More than 40 regression models with 2 to 31 regressions parameters are used and detailed results are presented...

A numerical model of the ground-water flow-system in the Portland Basin, Oregon and Washington, was used to test and refine the conceptual understanding of the flow system and estimate the effects of past and future human-caused changes to the ground-water system. Recharge to the basin in 1987-88 consisted primarily of...