Publications

A solute-transport model of an irrigated stream-aquifer system was recalibrated because of discrepancies between prior predictions of ground-water salinity trends during 1971-1982 and the observed outcome in February 1982. The original model was calibrated with a 1-year record of data collected during 1971-1972 in an 18-km reach of the Arkansas River Valley in southeastern Colorado. The model is i

A 1978–81 survey of submersed aquatic macrophytes in the tidal Potomac River showed that there were virtually no plants in the freshwater tidal river between Chain Bridge and Quantico, Virginia, decades after the disappearance of plants in the late 1930’s. Plant populations were monitored in subsequent years (1983–85) using qualitative shoreline surveys and quantitative resampling of the original

The Mill Run watershed is a structurally‐controlled synclinal basin on the eastern limb of the Massanutten Mountain complex of northwestern Virginia. Bedrock contacts are obscured by coarse sandstone debris from exposures near basin divides. Colluvium blankets more than half the basin, masking geomorphic surfaces, affecting vegetation patterns, and contributing to the convexity of the alluvial, te

Numerical modeling techniques are used to examine the hydrogeologic, design, and management factors governing the recovery efficiency of subsurface fresh-water storage. The modeling approach permitted many combinations of conditions to be studied. A sensitivity analysis was used that consisted of varying certain parameters while keeping constant as many other parameters or processes as possible. T

The major cations, anions, and detergents in a plume of contaminated groundwater at Otis Air Base on Cape Cod (Mass., U.S.A.) have moved approximately 3.5 km down gradient from the disposal beds. We hypothesize that the detergents form two distinct plumes, which consist of alkyl benzene sulfonates (ABS) detergents and linear alkyl sulfonates (LAS) and sodium dodecyl sulfate (NaLS) detergents. The

Denitrification in aquatic sediments was measured by an N2O reductase assay. Sediments consumed small added quantities of N2O over short periods (a few hours). In experiments with sediment slurries, N2O reductase activity was inhibited by O2, C2H2, heat treatment, and by high levels of nitrate (1 mM) or sulfide (10 mM). However, ambient levels of nitrate (<100 μM) did not influence activity, and m

Chemical data from three different series of diagenetic illite/smectites (I/S), analyzed statistically by two regresion techniques, indicate that the content of fixed-K per illite layer is not constant, but ranges from ∼0.55 per O10(OH)2 for illite layers in randomly interstratified I/S (R=0; > 50% smectite layers) to ∼1.0 per O10(OH)2 for illite layers formed in ordered I/S (R>0; <50% smectite la

No abstract available.

An instantaneous unit hydrograph (iuh) based on the theory of topologically random networks (topological iuh) is evaluated in terms of sets of basin characteristics and hydraulic parameters. Hydrographs were computed using two linear routing methods for each of two drainage basins in the southeastern United States and are the basis of comparison for the topological iuh's. Elements in the sets of b

A field method is proposed for determining the three-dimensional hydraulic conductivity tensor and specific storage of an anisotropic porous or fractured medium. The method, known as cross-hole testing (to distinguish it from conventional single-hole packer tests), consists of injecting fluid into (or withdrawing fluid from) packed-off intervals in a number of boreholes and monitoring the transien

No abstract available.

Thoreau's Bog is an ombrotrophic floating—mat Sphagnum bog developed in a glacial kettlehole and surrounded by a red maple swamp. Concentrations of dissolved organic carbon in the porewater of the bog average 36 mg/L and are greatest near the surface, especially during late summer. This distribution suggest that the upper layer of living and dead Sphagnum and moderately humified peat is the major