Publications

In 1989, the U.S. Geological Survey, in cooperation with the Harris-Galveston Coastal Subsidence District, began a field study to determine the depth to the water table and to estimate the rate of recharge in outcrops of the Chicot and Evangeline aquifers near Houston, Texas. The study area comprises about 2,000 square miles of outcrops of the Chicot and Evangeline aquifers in northwest...

Data collected from May 1991 through September 1993 to determine seasonal fluctuations in ground-water levels and to estimate directions of ground-water flow in the saturated zone at selected study sites at the Iowa Management Systems Evaluation Area in the Walnut Creek Watershed are presented. The Walnut Creek Watershed is located on glacial deposits of Wisconsinan age in central Iowa...

Agriculture is a major land use in the coastal prairie area located in the southern part of the Trinity River Basin. Crops grown in the area include rice, sorghum, and soybeans. Pesticide- use estimates for the area show that compounds with the highest use are the herbicides: molinate, propanil, thiobencarb, metolachlor, acifluorfen, bentazon, and atrazine and the insecticides: carbaryl...

No abstract available.

The Georgia-Florida Coastal Plain study unit covers nearly 62,600 square miles along the southeastern United States coast in Georgia and Florida. In 1990, the estimated population of the study unit was 9.3 million, and included all or part of the cities of Atlanta, Jacksonville, Orlando, Tampa, and St. Petersburg. Estimated freshwater withdrawn in the study unit in 1990 was nearly 5,075...

In parts of the upper reaches of the Red River Basin in Texas, streamflow is characterized by levels of salinity that limit its usefulness for most purposes. Large dissolved solids and dissolved chloride concentrations are caused primarily by flow from natural salt springs in tributaries to the Red River. To reduce downstream salinity in the Wichita River, a dam in the South Wichita...

The U.S. Geological Survey is conducting an assessment of water quality in the Georgia-Florida Coastal Plain study unit as part of the National Water-Quality Assessment Program. An initial activity of the program is to compile and analyze existing water-quality data for nutrients in each study unit. Ground-water quality data were compiled from three data sources, the U.S. Geological...

A number of potentially hazardous chemicals were used at an asphalt plant on the Fort Bragg U.S. Army Reservation near Fayetteville, North Carolina. This plant was demolished in the late 1960's. Samples collected from soil, ground water, surface water, and streambed sediment were tested for the presence of contaminants. The sediment immediately underlying the demolished asphalt plant...

The Georgia-Florida Coastal Plain study unit covers an area of nearly 62,000 square miles in the southeastern United States, mostly in the Coastal Plain physiographic province. Land resource provinces have been designated based on generalized soil classifications. Land resource provinces in the study area include: the Coastal Flatwoods, the Southern Coastal Plain, the Central Florida...

During the early phase of the Georgia-Florida National Water Quality Assessment study, existing information on nutrients was compiled and analyzed in order to evaluate the nutrient concentrations within the 61,545 square mile study unit. Evaluation of the nutrient concentrations collected at surface-water sites between October 1, 1970, and September 30, 1991, utilized the environmental

No abstract available.

The recent expansion of Typha domingensis (Typha) into areas of the Everglades previously dominated by Cladium jamaicense (Cladium) communities has led to competing hypotheses about the importance of nutrient concentration vs. hydroperiod in controlling the distribution of these species. In this study, experimental mixtures of Typha domingensis, Cladium jamaicense, and Eleocharis...