Central Valley Aquifer, Chapters A and B - MAE Class Websites

compaction and land subsidence in some areas (
and
). In some areas,
2004) (
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-
-
” subsection
of the “” section.
Surface Water and the Environment
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When water levels recover,
compaction and land subsidence can abate.
DEPTH-TO-WATER,
IN FEET BELOW LAND SURFACE
COMPACTION,
IN INCHES
200
400
600
12
0
Deep well
No data
1960 1970 1980
YEAR
Drought Drought
No data
1990
Development and Changes to the Hydrologic Budget 101
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nation
of and
-
().
-
During the droughts of 1976-77 and
1987-91, deliveries of imported water
to the west side of the San Joaquin
Valley were cut back. More groundwater
was pumped to meet the demand, resulting
in a drop in the water table and
consequent compaction.
Some elastic expansion of the aquifer
system has occured but the compacted
materials can never return to their
pre-compacted thickness.
Figure B16. Measured compaction in relation to head decline in the San Joaquin Valley. The effects of drought on groundwater levels
and associated subsidence also are evident. (Modified from Galloway and others, 1999; and Swanson, 1998.)