Ground Water Atlas of the United States -
Segment 1 California Nevada
Introduction
The California coastal region has been subjected to intense tectonic forces for
millions of years. Folding, faulting of marine sediments, and associated
volcanism resulted in the formation of the Klamath and the Salmon Mountains in
northern California and the Coast Ranges that extend along most of the
California coast. Terrestrial, marine, and volcanic rocks deposited in
intermontane valleys compose the aquifers herein called the Coastal Basins
aquifers (fig. 102). The California Department of Water Resources considers more
than 100 coastal basins to be "significant" because of the amount of ground
water potentially obtainable or the scarcity of surface-water sources in a
basin. Nearly all of the large population cen-ters in California are located in
the coastal basins.
The climate along the coast of California is moderated by the Pacific Ocean and
is essentially Mediterranean, characterized by cool winters and warm summers.
Precipitation is seasonal and usually in the form of rain. The greatest amounts
of precipitation fall during late autumn, winter, and early spring.
Precipitation amounts are greatest in northern California and progressively
decrease southward. Altitude also influences precipitation patterns; the
greatest amounts of precipitation fall in the mountains. Potential annual
evaporation in the valleys exceeds annual precipitation from San Francisco Bay
southward. As a result, most unregulated rivers in southern California are dry
in their lower reaches during the summer months.
Back to "GROUND-WATER QUALITY" - Forward
to "GEOLOGIC SETTING"
Back to Coastal Basins aquifers "Contents"
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