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E.G. Lappala

Publications and source records attributed to E.G. Lappala.

4 recordsLinked to original sources
USGS1979

Simulated changes in ground-water levels and streamflow resulting from future development (1970 to 2020) in the Platte River basin, Nebraska

Future changes in ground-water levels and streamflow caused by a limited set of water-resources development conditions were simulated with digital models of stream-aquifer systems within the Platte River Basin, Nebraska. Simulated water-resources use in the basin included private development of ground water for irrigation, Federal development of surface-water systems for irrigation, and development of ground water to supply municipal demands of Lincoln and Omaha. Simulated future conditions indicate that significant permanent declines in ground-water levels and streamflows may occur as a result of private development of ground water for irrigation. The largest simulated declines in ground-water levels were more than 80 feet by the year 2020 in upland areas in the Elkhorn and Middle Platte subbasins under conditions of rapid development of all irrigable lands. Simulated depletion of perennial streamflows by ground-water withdrawals indicated that future surface-water supplies may be limited in parts of the basin. Simulated depletions to major streams exceeded 60 percent of average perennial flow in the Elkhorn subbasin under conditions of rapid private development of ground water for irrigation. Simulations that evaluated the effects of combined private groundwater development with proposed Federal development of surface water for irrigation showed that in the project areas, ground-water level declines were reduced compared to "without project" conditions. In some project areas, simulated ground-water levels rose with the application of surface water in excess of consumptive-use requirements and soil-moisture storage capacities. The ground-water level rises would lead to waterlogged conditions in parts of the Middle Platte subbasin. The accuracy of the models developed in this study would be improved most by collection of additional data on ground-water withdrawals and storage properties at the aquifer.

Nebraska↗
USGS1978

Ground-water availability in the Hayes-Red Willow, Frenchman, and Meeker-Driftwood irrigation districts, southwest Nebraska

Surface-water supplies are diminishing in the Hitchcock-Red Willow and Frenchman Valley Irrigation Districts in southwest Nebraska. Stream depletions due to ground-water withdrawals upstream from Enders Reservoir (northwest of the study area) have resulted in a shortage of about 8,700 acre-feet per year. The availability of ground water to supply part of this deficit was examined. Two surficial aquifers that are currently economical to develop were investigated. The Ogallala aquifer of late Tertiary age which underlies all the area except the major stream valleys has a hydraulic conductivity averaging less than 200 gallons per day per square foot. Hydraulic conductivities and saturated thicknesses are greater north of and parallel to the Republican River from McCook to Culbertson. The most productive aquifer comprises alluvial deposits of Pleistocene and Holocene age which occupy the valleys of the Republican River and Frenchman Creek. Saturated thickness of this aquifer averages 5O feet, and hydraulic conductivity averages 1,000 gallons per day per square foot. The two aquifers are hydraulically connected except where the bedrock surface on both sides of the Republican River valley is higher than the water levels in the aquifers. Canal seepage and deep percolation have caused water levels to rise as much as 20 feet in the Hitchcock-Red Willow and Frenchman Valley Irrigation Districts north of the Republican River and as much as 40 feet in the Meeker-Driftwood Irrigation District south of the River. Streamflow accretions from ground water have not increased significantly on Frenchman, Blackwood, or Driftwood Creeks. Ground-water inflow to the Republican River has increased about 6 cubic feet per second between Trenton and McCook. A digital model of the stream aquifer system was used to simulate the pre-1976 hydrology and assess future conditions for two supply-well configurations as well as for existing private irrigation wells. The first supply-well configuration could sustain less than 37 percent of the well-field capacity of 5,970 acre-feet per year. Projected maximum stream depletions were 12 cubic feet per second on Frenchman Creek and 4 cubic feet per second on Blackwood Creek. The second supply-well configuration could sustain 79 percent of the well-field capacity of 2,780 acre-feet per year. Simulated stream depletions were less than 5 percent of mean annual flow at the end of 19 years. Model simulation indicated that existing wells could supply consumptive-irrigation requirements to district lands for at least 19 years, with well failures limited to areas in the Meeker-Driftwood District where the aquifer is thin.

Nebraska↗
USGS1976

Changes in the water supply in the Upper Republican Natural Resources District, Southwest Nebraska, from 1952-75

Use of ground water for irrigation has increased rapidly in the Upper Republican Natural Resources District in southwestern Nebraska in recent years. The principal aquifer being developed is composed of saturated and gravel of the Ogallala Formation of Tertiary age. Water-level declines of as much as 16 feet (4.9 meters) have occurred. Base flow of major streams draining the aquifer was reduced by as much as 19 percent between 1967 and 1975. Recoverable ground water in storage was reduced by about 1 percent. New withdrawal of ground water in 1975 was about 250 ,000 acre-feet (308 million cubic meters), compared with estimated recharge from precipitation of 176,000 acre-feet (217 million cubic meters). Water levels and streamflow will continue to decline if ground-water withdrawals continue at or greater than the 1975. (Woodard-USGS)

Open-File Report↗