High Plains Aquifer Water-Level Monitoring Study
Water-Level Changes in the High Plains Aquifer—Predevelopment to 1991
By Timothy McGrath and Jack T. Dugan
U.S. Geological Survey
Water-Resources Investigations Report 93-4088
Regional variability in water-level change in the High Plains aquifer underlying parts of South Dakota, Wyoming, Nebraska, Colorado, Kansas, New Mexico, Oklahoma, and Texas result from large regional differences in climate, land use, and ground-water withdrawals for irrigation. From the beginning of significant development of the High Plains aquifer for irrigation to 1980, substantial water-level declines have occurred in several areas. The estimated average area-weighted water-level decline from predevelopment to 1980 for the High Plains was 9.9 feet, an average annual decline of about 0.25 foot. These declines exceeded 100 feet in some parts of the Central and Southern High Plains. Declines were much smaller and less extensive in the Northern High Plains as a result of later irrigation development.
Since 1980, water levels in those areas of large declines in the Central and Southern High Plains have continued to decline, but at a much slower annual rate. The estimated average area-weighted water-level decline from 1980 to 1991 for the entire High Plains was 1.41 feet, an average annual decline of about 0.13 foot. The relatively small decline since 1980, in relation to the declines prior to 1980, is associated with a decrease in ground-water application for irrigated agriculture and greater than normal precipitation. Water-conserving practices and technology, in addition to reductions in irrigated acreages, contributed to the decrease in ground-water withdrawals for irrigation.
Water-level declines exceeding 20 feet since 1980, however, are widespread in parts of southwestern Kansas, east-central New Mexico, and the Oklahoma and Texas Panhandles. Widespread declines of 10 to 20 feet and exceeding 20 feet in smaller areas occurred in northeastern Colorado, northwestern Kansas, southwestern Nebraska, and the Nebraska Panhandle from 1980 to 1991. Water-level rises exceeding 20 feet occurred in the extreme Southern High Plains in Texas where precipitation was much greater than normal from 1980 to 1991. Widespread water-level rises from 5 to 20 feet occurred in eastern Nebraska during the same period in association with greater than normal precipitation.
The estimated average area-weighted water-level decline from 1990 to 1991 was 0.42 foot, even though precipitation was slightly greater than normal in 1990 in the High Plains. Water-level declines of 3 to 5 feet were widespread in the intensively irrigated areas of southwestern Kansas and the northern part of the Southern High Plains in Texas. These declines appear to be related to 1990 precipitation patterns in the Southern High Plains in Texas, but not in southwestern Kansas. Declines of 1 to 3 feet were common throughout the intensively irrigated areas of the Northern High Plains and the less intensively irrigated areas of the Central and Southern High Plains. Water levels continued to rise, generally 1 to 3 feet, in the extreme Southern High Plains in Texas. Rises of 1 to 3 feet also occurred in parts of eastern Nebraska where precipitation was as much as 4 to 6 inches greater than normal in 1990.
This report (WRIR 93-4088) is available online.
To obtain a copy of this report, please contact:
USGS Nebraska Water Science Center
5231 South 19th Street
Lincoln, Nebraska 68512-1271
Phone (402) 328-4100
FAX (402) 328-4101
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