Publications

A digital model of two-dimensional groundwater flow was used to estimate the hydraulic properties of the Edwards Aquifer in a 151 sq mi area near Austin, Texas. The transmissivity, hydraulic conductivity, and specific yield were estimated for the part of the aquifer that discharges at Barton Springs in Austin. The aquifer is composed of the Edwards and overlying Georgetown Limestones of Cretaceous

Statistical summaries of available water-quality data collected from 90 wells and 3 springs in the Edwards aquifer near San Antonio, Texas, are presented. The statistical summaries provide information on the range in values for each water-quality constituent as well as the mean value, the standard deviation about the mean; and for those constituents with five or more analyses, the percentage of ob

Significant amounts of SO42−, Na+, and OH− are incorporated in marine biogenic calcites. Biogenic high Mg-calcites average about 1 mole percent SO42−. Aragonites and most biogenic low Mg-calcites contain significant amounts of Na+, but very low concentrations of SO42−. The SO42− content of non-biogenic calcites and aragonites investigated was below 100 ppm. The presence of Na+ and SO42− increases

A model for the optimal allocation of water resources was developed for a multiaquifer groundwater and surface water system near Livermore, California. The complex groundwater system was analyzed using a transient, quasi-three-dimensional model that considers the nonlinear behavior of the unconfined aquifer. The surface water system consists of a reservoir that discharges water to three streams wh

A simple two-dimensional dam-break model is developed for flood plain study purposes. Both a finite difference grid and an irregular triangle element integrated finite difference formulation are presented. The governing flow equations are approximately solved as a diffusion model coupled to the equation of continuity. Application of the model to a hypothetical dam-break study indicates that the ap

Conceptual models for tidal period and low-frequency variations in sea level, currents, and mixing processes in the northern and southern reaches of San Francisco Bay describe the contrasting characteristics and dissimilar processes and rates in these embayments: The northern reach is a partially mixed estuary whereas the southern reach (South Bay) is a tidally oscillating lagoon with density-driv

The characteristics of the Coastal Plain aquifers of South Carolina are being studied as a part of the Regional Aquifer System Analysis program of the United States Geological Survey. Potentiometric maps were constructed for the Middendorf aquifer of Cretaceous age and for the Floridan aquifer system and its sand facies equivalent, Tertiary sand aquifer, prior to development. Also constructed was

This review of the preceding papers suggests that temporal variability in San Francisco Bay can be characterized by four time scales (hours, days-weeks, months, years) and associated with at least four mechanisms (variations in freshwater inflow, tides, wind, and exchange with coastal waters). The best understood component of temporal variability is the annual cycle, which is most obviously influe

The complex variable boundary element method (CVBEM) is used to approximate several potential problems where analytical solutions are known: A modelling result produced from the CVBEM is a measure of relative error in matching the known boundary condition values of the problem. A CVBEM error-reduction algorithm is used to reduce the relative error of the approximation by adding nodal points in bou

San Francisco Bay, the largest bay on the California coast, is a broad, shallow, turbid estuary comprising two geographically and hydrologically distinct subestuaries: the northern reach lying between the connection to the Pacific Ocean at the Golden Gate and the confluence of the Sacramento-San Joaquin River system, and the southern reach (herein called South Bay) between the Golden Gate and the

The Great Salt Lake rose 5.0 feet from September 25,1983, to July 1, 1984, the second largest seasonal rise on record since 1847. The maximum seasonal rise was observed the previous year when the lake rose 5.1 feet from September 18,1982, to June 30,1983. The lake declined only 0.5 foot during summer 1983; thus, the net rise from September 18,1982, to July 1,1984, was 9.6 feet. By comparison, the

This is the twenty-second in a series of annual reports that describe ground-water conditions in Utah. Reports in this series, published cooperatively by the U.S. Geological Survey and the Utah Division of Water Resources, provide data to enable interested parties to keep abreast of changing ground-water conditions.This report, like the others in the series, contains information on well constructi