Pacific Southwest Research Station

Publication Information

Title: Estimating risk of debris slides after timber harvest in northwestern California

Author: Neely, M. K.; Rice, R. M.

Date: 1990

Source: Bull. Assoc. Engineering Geologists XXVII(3): 281-289.

Description: Abstract - The risk of debris slides resulting from logging must often be appraised by foresters planning timber harvests. The Board of Forestry of the State of California commissioned the development of a Mass Movement Checklist to guide foresters making such appraisals. The classification accuracy of the Checklist, tested using 50 logging-related debris slides and 50 logged sites that had not produced debris slides, was correct at 60 sites in northwestern California. Its low accuracy is attributed to low variability of several constituent variables. Although the Checklist may be useful in distinguishing between generally stable and unstable areas, it is of little help in making site-specific decisions within a timber harvest area. The data collected to test the Checklist were used in a linear discriminant analysis to develop a three-variable equation to predict post-logging debris slide risk. It correctly classified 77 percent of the sites. Both analyses suggest that the relative debris slide risk associated with logging is best estimated using geomorphic variables which can change markedly over short distances and which are good surrogates for the forces affecting slope stability.

Key Words: PSW4351, debris slides, timber harvest, California, slope stability, landscape, California, erosion

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Neely, M. K.; Rice, R. M.  1990.  Estimating risk of debris slides after timber harvest in northwestern California  Bull. Assoc. Engineering Geologists XXVII(3): 281-289..