Publications

Ground-water conditions during 1993 and recent ground-water level and quality trends in Georgia were evaluated using data from precipitation, ground-water, and ground-water quality monitoring networks. Data for 1993 included in this report are from precipitation records from 10 National Weather Service stations, continuous water-level records from 72 wells, and chloride analyses from 13...

The effects of different agricultural land-management practices on sediment, nutrients, and selected pesticides in surface water, and on nutrients and pesticides in ground water were studied in four small basins in the Piedmont of North Carolina. The basins included two adjacent basins in row-crop fields, a mixed land-use basin, and a forested basin. One of the row-crop fields was farmed...

The Hueco bolson aquifer is being pumped at increasing rates to supply water for El Paso, Texas, and Ciudad Juarez, Mexico. Water-use projections for 1984-2000 indicate that the upward trend in pumping rates probably will continue, which will put an increasing burden on the limited freshwater resources of the aquifer. Near El Paso, saline water in the Rio Grande alluvium overlies...

Hydrologic data were collected in the Big Spring Basin located in Clayton County, Iowa, during the 1991 water year. The data were collected by the U.S. Geological Survey in cooperation with the Iowa Department of Natural Resources, Geological Survey Bureau, to provide information on variation and movement of agricultural chemicals in the hydrologic cycle in the basin. Precipitation...

No abstract available.

No abstract available

Production and decomposition rates were calculated for Spartina patens in a mesohaline coastal marsh in Louisiana. Production was estimated to be 800 g m2 yr-1 during 1991 and 1,696 g m-1 yr-1 during 1992. The relative decomposition rate of S. patens stems was -0.001152 g g-1 d-1 which may be restated as a half life of 395 days. Both production and decomposition rates for this area are...

Habitat management decisions for diving ducks in winter are limited by the lack of information concerning their use of nearshore and offshore zones. Therefore, we compared diets of redheads (Aythya americana) collected from nearshore (n = 206) and offshore (n = 72) zones during winters at the Chandeleur Islands, Louisiana, 1987-89. A greater (P 0.05) proportion of redheads from nearshore...

No abstract available.

Although the Belding’s Savannah sparrow (Passerculus sandwichensis beldingl) is listed as endangered in California, little is known about the factors that affect its abundance and distribution. Numbers of breeding pairs, nesting territory sizes, and vegetation characteristics were measured at fourteen study plots in two southern California coastal wetlands, Tijuana Estuary and Los...

No abstract available.

Field measurements of canopy structure and species composition are related to spectral reflectance measurements taken with a radiometer over a number of marsh sites. Marsh vegetation types are discussed in terms of their characteristic canopy structure and phenology; the influence of these characteristics on spectral reflectance will be examined. Vegetation types that are discussed...