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Jack T. Dugan

Publications and source records attributed to Jack T. Dugan.

5 recordsLinked to original sources
USGS2000

Simulation and analysis of soil-water conditions in the Great Plains and adjacent areas, central United States, 1951-80

Ground-water recharge and consumptive-irrigation requirements in the Great Plains and adjacent areas largely depend upon an environment extrinsic to the ground-water system. This extrinsic environment, which includes climate, soils, and vegetation, determines the water demands of evapotranspiration, the availability of soil water to meet these demands, and the quantity of soil water remaining for potential ground-water recharge after these demands are met. The geographic extent of the Great Plains contributes to large regional differences among all elements composing the extrinsic environment, particularly the climatic factors. A soil-water simulation program, SWASP, which synthesizes selected climatic, soil, and vegetation factors, was used to simulate the regional soil-water conditions during 1951-80. The output from SWASP consists of several soil-water characteristics, including surface runoff, infiltration, consumptive water requirements, actual evapotranspiration, potential recharge or deep percolation under various conditions, consumptive irrigation requirements, and net fluxes from the ground-water system under irrigated conditions. Simulation results indicate that regional patterns of potential recharge, consumptive irrigation requirements, and net fluxes from the ground-water system under irrigated conditions are largely determined by evapotranspiration and precipitation. The local effects of soils and vegetation on potential recharge cause potential recharge to vary by more than 50 percent in some areas having similar climatic conditions.

Water Supply Paper↗
USGS1986

Hydrologic characteristics of soils in parts of Arkansas, Colorado, Kansas, Missouri, Nebraska, New Mexico, Oklahoma, South Dakota, and Texas

Certain physical characteristics of soils, including permeability, available water capacity, thickness, and topographic position, have a definite effect on the hydrology of an area. They control the rate at which precipitation infiltrates or is transmitted through the soil, and thus they have a significant role in determining the rates both of ground-water recharge and surface runoff. In studies of ground-water hydrology, it commonly is useful to differentiate soils areally according to their physical characteristics and to assign values indicating the hydrologic responses of soils in the different areas. In 1980 the U.S. Geologic Surey began a study termed the “Central Midwest Region Aquifer System Analysis,” Jorgensen and Signor, 1981). The regional aquifer system is defined as including all aquifers of Cretaceous age or older in all or parts of nine States included in this report. For part of this analysis, use of a soil-moisture model is planned to obtain estimates of actual evapotranspiraion and recharge to the regional aquifer system. Data for the hydrologic characteristics of the soils in the study area are required as input to this soil-moisture model.

Arkansas, Colorado, Kansas, Missouri, Nebraska, Ne↗
USGS1984

Hydrologic characteristics of Nebraska soils

The influence of the physical characteristics of soil on hydrology is frequently neglected. In this report, the effects of five characteristics on the hydrologic responses of soils in Nebraska are evaluated quantitatively, soils are grouped through use of a simplified coding system according to similarities in hydrologic responses, and are mapped according to these responses. General soils maps of the U.S. Department of Agriculture Soil Conservation Service and data for the physical properties of the soils proved well-suited to hydrologic interpretation. This interpretation of the maps and data led to the selection of three characteristics as classification variables: Average permeability of the 60-inch soil profile, average maximum soil slope, and depth to the seasonal high water table. Permeability of the least permeable horizon and available water capacity, although not needed as classification variables, are useful in explaining some of the hydrologic responses of soils. The primary soil units used in groupings and interpretation of the soils for this study are the soil associations. A computer program is presented that sorts the soils into groups and calculates statistics for each group. The 147 soil associations in Nebraska were thus sorted into 29 hydrologic soil groups. The location and extent of these hydrologic soil groups are shown on maps at scales of 1:750,000 and 1:250,000 for the State.

Water Supply Paper↗
USGS1978

Predictive analyses of ground-water discharges in the Willow Creek Watershed, northeast Nebraska

Ground-water discharge to Willow Creek, which drains a 204 mi 2 watershed in northeast Nebraska was predicted for six combinations of conditions of climate and ground-water development. A digital model of the ground water/surface-water system was stressed with recharge and withdrawal functions determined from a linear reservoir model of the soil zone. The geohydrologic system includes a regional aquifer which containssand and gravel ranging in age from Pliocene through Pleistocene. The regional aquifer is unconfined in the western part of the watershed and confined in the eastern part. The confining layer, or blue clay, in the east is of Pleistocene age and comprises principally saturated eolian silts with very fine sand interbeds overlying a basal lacustrine clay. Where unconfined conditions exist in the regional aquifer, perennial flow of Willow Creek is sustained principally by ground-water discharge. Where confined conditions exist, the low hydraulic conductivity of the blue clay effectively isolates the regional aquifer from Willow Creek. The stream-aquifer models were tested by comparing simulated against measured water levels and streamflow during 1975 and 1976. Agreement between simulated and observed values was obtained by modifying initial estimates of aquifer hydraulic conductivity and specific storage. Future ground-water discharge to Willow Creek (base flow) was simulated by super-imposing different patterns of ground-water withdrawals upon variations from average recharge for a monthly climatic sequence identical with the period 1931 to 1954. Frequency analyses of the simulated monthly base flows showed that they would be less than 12 feet 3 per second at least 50 percent of the time under all but completely undeveloped conditions. Simulated water-level declines in the regional aquifer at the end of the pumping season after a drought period similar to that of the 1930's were less than 5 feet where unconfined conditions exist and were more than 80 feet where confined conditions exist.

Nebraska↗