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Calculation of a water budget and delineation of contributing sources to drainflows in the western San Joaquin Valley, California

Open-File Report 94-45

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Abstract

Geohydrologic data and a ground-water flow model were used to calculate a water budget and evaluate the contribution of regional ground-water flow to on-farm drainflow in a part of the western San Joaquin Valley, California. Regional ground-water flow is affected by the distribution of unconsoli- dated coarse- and fine- grained sediment. Predomi- nantly coarse-grained sediment in the upslope areas results in a water table more than 3 meters below land surface, but the low-lying areas are underlain by predominantly fine-grained sediments and have a water table within 3 meters of land surface. The vertical component of flow is downward in the upslope areas, but upward at some locations in the low-lying areas. Model simulation results indicate that about 89 percent of the drainflow (18.5 times 10(6) cubic meters per year) originates as recharge within the fields that overlie the drainage systems, and 11 percent of the drainflow (2.3 times 10(6) cubic meters per year) is lateral-flowing ground water and upward deept percolation originating as recharge at fields upslope from the drainage systems. The lateral-flow and upward deep perco- lation can move substantial distances (as great as 3.6 kilometers horizontally and from depths greater than 29 meters below land surface), and require from 10 to more than 90 years to reach the drainage systems. (USGS)

Additional Publication Details

Publication type:
Report
Publication Subtype:
USGS Numbered Series
Title:
Calculation of a water budget and delineation of contributing sources to drainflows in the western San Joaquin Valley, California
Series title:
Open-File Report
Series number:
94-45
Edition:
-
Year Published:
1994
Language:
ENGLISH
Publisher:
U.S. Geological Survey ; USGS Earth Science Information Center, Open-File Reports Section [distributor],
Description:
v, 39 p. :ill., maps ;28 cm.