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Management of Coarse Sediment in Regulated Rivers of California
G. Mathias Kondolf, University of California, Berkeley
W.V. Graham Matthews, University of California, Berkeley
UC Water Resources Center Technical Completion Report W-748
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ABSTRACT: There are significant problems in the management of coarse
sediment (sand and gravels) in regulated rivers of California.
Unfortunately, these have been generally treated (or ignored) on
a case-by-case basis, however, the effects are pervasive and
profound, with substantial costs and severe environmental impacts.
Problems arise due to the human manipulation of coarse sediment
through reservoir construction, which blocks the movement of coarse
sediment down the river, and through instream gravel mining, which
removes this material from the river system for use primarily in
construction-related projects. Impacts identified include: bed
material coarsening, channel incision, channel geometry changes,
hydrologic regime alterations, and changes in transport of
sediment. Many of these impacts result in damage to or destruction
of anadromous fisheries habitat, and are partly responsible for the
dramatic declines in anadromous fisheries resources in the last 50
years. other types of impacts include damage to instream
structures, loss of riparian habitat, and increased risk of
damaging channel changes.
We documented these types of impacts on a set of major river
drainages on the western slope of the Sierra Nevada, along with
several rivers in the Coast Ranges. We have reviewed the
institutional and regulatory framework for both reservoir operation
and instream mining, finding inconsistencies and lack of standard
requirements for monitoring and mitigation of environmental
impacts. various techniques that comprise the existing piecemeal
approach to restoration and enhancement of coarse sediment
resources were inventoried. We propose alternative strategies for
management of coarse sediment that
SUGGESTED CITATION:
G. Mathias Kondolf and W.V. Graham Matthews,
"Management of Coarse Sediment in Regulated Rivers of California"
(December 1, 1991).
University of California Water Resources Center.
Technical Completion Reports.
Paper 748.
http://repositories.cdlib.org/wrc/tcr/748
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