Search USGS⌕ Search

Geology topics

L. E. Dunlap

Publications and source records attributed to L. E. Dunlap.

7 recordsLinked to original sources
USGS1985

Geohydrology and model analysis of stream-aquifer system along the Arkansas River in Kearny and Finney Counties, southwestern Kansas

A study was made, in cooperation with the Division of Water Resources, Kansas State Board of Agriculture, to determine geohydrologic conditions in an area comprising nearly 850,000 acres along the Arkansas River valley in Kearny and Finney Counties, southwestern Kansas. The Arkansas River meanders atop and interacts hydraulically with the area's multilayered, unconsolidated aquifer system. Declines in static water levels in wells in the heavily pumped lower aquifer ranged from 20 to 80 feet during 1974-80. The river is dry in much of the area. A digital computer model was calibrated to simulate the trends of historic water levels. Simulated 1974-80 conditions depicted an average annual recharge to the unconsolidated aquifer system of 66,900 acre-feet from precipitation and 36,200 acre-feet from river and canal seepage and boundary inflow. Simulated average annual discharge consisted of 634,800 acre-feet from pumpage and boundary outflow. Simulated average annual recharge to the unconsolidated aquifer system was 531,700 acre-feet less than average annual discharge, indicating the ground-water resource is currently (1982) being mined in the study area. Simulation also indicated that there would be sufficient saturated thickness in 2005 for irrigation if 1980 hydrologic conditions continued. Seepage losses from the Arkansas River and irrigation canals are a major source of recharge to the unconsolidated aquifer system. Therefore, the amount of flow in the Arkansas River would be important in determining the rate of future water-level declines in the study area. Streamflow seepage losses could be decreased by (1) decreasing the number of wells pumping in the study area in order to reduce downward leakage from the valley aquifer, or (2) increasing streamflow discharge in order to recharge the valley aquifer. The rate and direction of flow between the river and the valley aquifer depend on the hydraulic conductivity of the streambed and the hydraulic gradient between the river stage and the water table. As long as river stage remains high, the water table in the valley aquifer continues to rise. Seepage from the river to the valley aquifer decreases as the altitude difference between the river stage and the valley aquifer decreases, becoming insignificant when the water level in the valley aquifer nearly equals river stage. However, a rise in the water table in the valley aquifer because of recharge from the river will correspond to increased downward leakage to the lower aquifer, impeding recharge to the valley aquifer.

Kansas↗
USGS1984

Projected effects of ground-water withdrawals in the Arkansas River Valley, 1980-99, Hamilton and Kearny Counties, southwestern Kansas

A study was made, in cooperation with the Kansas State Board of Agriculture, to determine the effects that additional ground-water development would have on streamflow and water levels on an area along the Arkansas River in Hamilton and Kearny Counties, southwestern Kansas. A computer model was used to simulate the changes in streamflow and water levels from 1980 through 1999. Six pumpage options were tested using variations in pumpage rate and number of wells pumping in the model area. If the full amount appropriated by water rights were pumped rather than actual 1979 conditions of pumpage, annual pumpage would be reduced 24 percent, but net annual river loss would be reduced only 1 percent. A pumpage increase of approximately 19 percent over 1979 pumpage conditions would cause an increase of net annual river loss from 5 to 9 percent. Increased pumpage, in the form of additional wells in the model area, would cause additional ground water to be removed from storage in the aquifer and an increase in net annual river loss.

Kansas↗
USGS1984

Interpolating water-table altitudes in west-central Kansas using kriging techniques

Kriging is a regionalization technique that incorporates the autocorrelation between known data values in its estimation of values at unmeasured sites. This technique is reproducible, accepts irregularly spaced data, uses only measured values closely surrounding points at which values are estimated, is an exact interpolator at measured data points, and calculates an error of estimate. Kriging was used to interpolate water-table altitudes for 1978 and an average 1978-80 for the Ogallala aquifer in the Western Kansas Groundwater Management District No. 1. An altitude and an error of estimate were provided at the center of each one-mile section of the district. The data were related to altitudes of the bedrock and the 1950 water table. A digital-contouring procedure was used to construct maps of the water table for 1978 and for the average 1978-80, the errors of estimate, the saturated thickness of the aquifer for 1978 and for the average 1978-80, and the percentage changes in saturated thickness since 1950. Maps made by kriging compared favorably with maps contoured manually by the point-intersection method.

Water Supply Paper↗
USGS1983

Geohydrology and model analysis of the stream-aquifer system along the Arkansas River in Kearny and Finney counties, southwestern Kansas

A study was made, in cooperation with the Division of Water Resources, Kansas State Board of Agriculture, to determine geohydrologic conditions in an area comprising nearly 850,000 acres along the Arkansas River valley in Kearny and Finney Counties, southwestern Kansas. The Arkansas River meanders atop and interacts hydraulically with the area's multilayered, unconsolidated aquifer system. Declines in static water levels in wells in the heavily pumped lower aquifer ranged from 20 to 80 feet during 1974-80. The river is dry in much of the area. A digital computer model was calibrated to simulate the trends of historic water levels. Simulated 1974-80 conditions depicted an average annual recharge to the unconsolidated aquifer system of 66,900 acre-feet from precipitation and 36,200 acre-feet from river and canal seepage and boundary inflow. Simulated average annual discharge consisted of 634,800 acre-feet from pumpage and boundary outflow. Simulated average annual recharge to the unconsolidated aquifer system was 531,700 acre-feet less than average annual discharge, indicating the ground-water resource is currently (1982) being mined in the study area. Simulation also indicated that there would be sufficient saturated thickness in 2005 for irrigation if 1980 hydrologic conditions continued. Seepage losses from the Arkansas River and irrigation canals are a major source of recharge to the unconsolidated aquifer system. Therefore, the amount of flow in the Arkansas River would be important in determining the rate of future water-level declines in the study area. Streamflow seepage losses could be decreased by (1) decreasing the number of wells pumping in the study area in order to reduce downward leakage from the valley aquifer, or (2) increasing streamflow discharge in order to recharge the valley aquifer. The rate and direction of flow between the river and the valley aquifer depend on the hydraulic conductivity of the streambed and the hydraulic gradient between the river stage and the water table. As long as river stage remains high, the water table in the valley aquifer continues to rise. Seepage from the river to the valley aquifer decreases as the altitude difference between the river stage and the valley aquifer decreases, becoming insignificant when the water level in the valley aquifer nearly equals river stage. However, a rise in the water table in the valley aquifer because of recharge from the river will correspond to increased downward leakage to the lower aquifer, impeding recharge to the valley aquifer.

Kansas↗
USGS1983

Analysis and computer simulation of stream-aquifer hydrology, Arkansas River Valley, southwestern Kansas

A study was made, in cooperation with the Division of Water Resources, Kansas State Board of Agriculture, to determine geohydrologic conditions underlying nearly 110,000 acres of the Arkansas River Valley between the Colorado-Kansas State line and the Bear Creek Fault zone in southwestern Kansas. The Arkansas River meanders atop and interacts hydraulically with the area's unconfined sand and gravel aquifer. Owing to decreasing recharge and increasing discharge during the 1970's, water levels declined an average of 4 feet during 1970-79. Average annual streamflow at Syracuse, Kansas, also decreased from 232 cubic feet per second during 1951-69 to 85 cubic feet per second during 1970-79. A digital-computer model was calibrated to simulate the trends of historic water levels and streamflow during 1970-79. Simulated 1975-79 conditions depict an annual recharge to the aquifer of 15,000 acre-ft (acre-feet) from river leakage, 9,000 acre-ft from boundary inflow, and 50,000 acre-ft from deep percolation. Simulated annual discharge consists of 12,000 acre-ft to boundary outflow across the Bear Creek Fault zone, 1,000 acre-ft as leakage to the Arkansas River, 11,000 acre-ft to groundwater evaporation, and 57,000 acre-ft to pumpage. Simulated annual recharge was 7,000 acre-ft less than simulated annual discharge of 81,000 acre-ft. Simulation indicates that: (1) The long-term effects of less recharge from smaller than average amounts of annual precipitation during the 1970's were offset by more recharge during brief, timely periods of much greater than the mean monthly amounts of precipitation, and (2) the effects of the increased pumpage were partly offset by increased recharge resulting from increased irrigation. Model results indicate that the water-level decline and streamflow shortage during 1970-79 were affected more directly by departures from historic (1951-69) rates of incoming streamflow than by either the smaller than average amounts of precipitation or the increased pumpage during the 1970's. Results also indicate that waterlevel declines and streamflow reduction would stabilize or reverse during 1980-82 if one of the following conditions prevailed: (1) Monthly precipitation increased to 25 percent greater than the normal for 3 years. (2) pumpage decreased to 50 percent of the 1979 rate or, (3) incoming streamflow increased to the 1951-69 rate.

Water Supply Paper↗
USGS1982

Geohydrology of principal aquifers in the Republican River basin, Kansas

Principal aquifers in the Republican River basin in Kansas are unconsolidated alluvial deposits. One such aquifer is formed by the Ogallala Formation of Miocene age which covers most of the western part of the area. Because saturated thickness of the aquifer decrease northeastward, maximum yields to irrigation wells decrease in that direction from 2,000 to 500 gallons per minute. The Grand Island Formation of Pleistocene age occurs in an ancestral channel of the Republican River in northeast Jewell and northwest Republic counties. The maximum yield to wells from this aquifer was estimated to be 2,000 gallons per minute. Quaternary alluvium of Pleistocene and Holocene age occurs in most major stream valleys. The aquifer in the Republican River valley yields as much as 2,000 gallons per minute to irrigation wells. Water levels in the Ogallala Formation commonly declined from 5 to 40 feet during 1950-77 as a result of irrigation withdrawals. Recharge from irrigation by stream diversions have raised water levels as much as 25 feet in the Grand Island Formation and as much as 15 feet in the Quaternary alluvium of the Prairie Dog Creek valley. (USGS)

Open-File Report↗
USGS1979

Hydrologic and related data for water-supply planning in an intensive-study area, northeastern Wichita County, Kansas

Data are presented that result from an intensive geohydrologic study for water-supply planning in a 12-square-mile area in northeastern Wichita County, Kansas. These data include records of wells, test drilling, chemical analyses, ground-water levels, rainfall, soilmoisture, well yield, solar radiation, crop yield, and crop acreage. Data indicate that water levels in the unconsolidated aquifer are declining at an average annual rate of about 1 to 2 feet per year (1950-78). This decline is the aquifer's response to pumping by irrigation wells for watering corn, wheat, grain sorghum, and other crops.

Kansas↗