Temporal and spatial distribution of landslides in the Redwood Creek Basin, Northern California

By:
Edited by: C. Nicholas MedleyGlenn Patterson, and Melanie J. Parker

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Abstract

Mass movement processes are a dominant means of supplying sediment to mountainous rivers of north coastal California, but the episodic nature of landslides represents a challenge to interpreting patterns of slope instability. This study compares two major landslide events occurring in 1964-1975 and in 1997 in the Redwood Creek basin in north coastal California. In 1997, a moderate-intensity, long-duration storm with high antecedent precipitation triggered 317 landslides with areas greater than 400 m2 in the 720-km2 Redwood Creek basin. The intensity-duration threshold for landslide initiation in 1997 was consistent with previously published values. Aerial photographs (1:6,000 scale) taken a few months after the 1997 storm facilitated the mapping of shallow debris slides, debris flows, and bank failures. The magnitude and location of the 1997 landslides were compared to the distributions of landslides generated by larger floods in 1964, 1972, and 1975. The volume of landslide material produced by the 1997 storm was an order of magnitude less than that generated in the earlier period. During both periods, inner gorge hillslopes produced many landslides, but the relative contribution of tributary basins to overall landslide production differed. Slope stability models can help identify areas susceptible to failure. The 22 percent of the watershed area classified as moderately to highly unstable by the SHALSTAB slope stability model included locations that generated almost 90 percent of the landslide volume during the 1997 storm.

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Additional publication details

Publication type Conference Paper
Publication Subtype Conference Paper
Title Temporal and spatial distribution of landslides in the Redwood Creek Basin, Northern California
Year Published 2011
Language English
Publisher U.S. Geological Survey
Publisher location Reston, VA
Contributing office(s) Western Ecological Research Center
Description 6 p.
Larger Work Type Report
Larger Work Subtype Federal Government Series
Larger Work Title Observing, studying, and managing for change: Proceedings of the Fourth Interagency Conference on Research in the Watersheds (SIR 2011-5169)
First page 149
Last page 154
Conference Title Fourth Interagency Conference on Research in the Watersheds
Conference Location Fairbanks, AK
Conference Date September 26-30, 2011
Country United States
State California
Other Geospatial Redwood Creek Basin
Online Only (Y/N) N
Additional Online Files (Y/N) N