Mathematical model of San Juan Valley ground-water basin, San Benito County, California
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Abstract
A mathematical model study of the San Juan Valley ground-water basin in San Benito County, Calif., has quantitatively described the ground-water hydrology of the basin under past, present, and future conditions of development. An analysis of conditions in the basin prior to large-scale ground-water development indicates that net recharge equaled 9.23 cubic feet per second and occurred as subsurface flow to the eastern part of the basin and infiltration of rain, direct runoff, and minor streamflows. Net predevelopment discharge equaled 9.23 cubic feet per second and occurred as aquifer discharge to the San Benito River. The 9.23 cubic feet per second of predevelopment recharge is considered to be perennial recharge to the basin.
Large-scale ground-water development occurred in the area during the period 1945-68 and caused water levels to decline throughout most of the basin. Progressive depletion of aquifer storage during this period changed the San Benito River from a gaining (perennial) stream to a losing stream along most of its reach in the basin area. Net discharge from the basin during the period 1945-68 averaged 18.10 cubic feet per second. Of this amount 17.82 cubic feet per second occurred as pumpage from wells, and
0.28 cubic foot per second occurred as basin discharge to the San Benito River. Net recharge to the basin during the same period averaged 13.57 cubic feet per second. Of this amount 4.34 cubic feet per second occurred as infiltration from the San Benito River and 9.23 cubic feet per second occurred as perennial recharge.
Use of the calibrated mathematical model to simulate quantities of imported water entering the basin from the San Benito River indicates that water levels in San Juan Valley will stabilize or recover when additional recharge equals or exceeds 3,000 acre-feet per year.
Study Area
| Publication type | Report |
|---|---|
| Publication Subtype | USGS Numbered Series |
| Title | Mathematical model of San Juan Valley ground-water basin, San Benito County, California |
| Series title | Water-Resources Investigations Report |
| Series number | 73-58 |
| DOI | 10.3133/wri7358 |
| Year Published | 1974 |
| Language | English |
| Publisher | U.S. Geological Survey |
| Description | iv, 39 p. |
| Country | United States |
| State | California |
| County | San Benito County |
| Other Geospatial | San Juan Valley |
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