Assessment of topographic and drainage network controls on debris-flow travel distance along the west coast of the United States

Italian Journal of Engineering Geology and Environment; 5th International Conference on Debris-Flow Hazards "Mitigation, Mechanics, Prediction and Assessment"
By: , and 

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Abstract

To better understand controls on debris-flow entrainment and travel distance, we examined topographic and drainage network characteristics of initiation locations in two separate debris-flow prone areas located 700 km apart along the west coast of the U.S. One area was located in northern California, the other in southern Oregon. In both areas, debris flows mobilized from slides during large storms, but, when stratified by number of contributing initiation locations, median debris-flow travel distances in Oregon were 5 to 8 times longer than median distances in California. Debris flows in Oregon readily entrained channel material; entrainment in California was minimal. To elucidate this difference, we registered initiation locations to high-resolution airborne LiDAR, and then examined travel distances with respect to values of slope, upslope contributing area, planform curvature, distance from initiation locations to the drainage network, and number of initiation areas that contributed to flows. Results show distinct differences in the topographic and drainage network characteristics of debris-flow initiation locations between the two study areas. Slope and planform curvature of initiation locations (landslide headscarps), commonly used to predict landslide-prone areas, were not useful for predicting debris-flow travel distances. However, a positive, power-law relation exists between median debris-flow travel distance and the number of contributing debris-flow initiation locations. Moreover, contributing area and the proximity of the initiation locations to the drainage network both influenced travel distances, but proximity to the drainage network was the better predictor of travel distance. In both study areas, flows that interacted with the drainage network flowed significantly farther than those that did not. In California, initiation sites within 60 m of the network were likely to reach the network and generate longtraveled flows; in Oregon, the threshold was 80 m.

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Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Assessment of topographic and drainage network controls on debris-flow travel distance along the west coast of the United States
Series title Italian Journal of Engineering Geology and Environment; 5th International Conference on Debris-Flow Hazards "Mitigation, Mechanics, Prediction and Assessment"
DOI 10.4408/IJEGE.2011-03.B-024
Year Published 2011
Language English
Publisher Research Center CERI
Publisher location Rome, Italy
Contributing office(s) Geologic Hazards Science Center
Description 11 p.
Larger Work Type Article
Larger Work Subtype Journal Article
Larger Work Title Italian Journal of Engineering Geology and Environment; 5th International Conference on Debris-Flow Hazards "Mitigation, Mechanics, Prediction and Assessment"
First page 199
Last page 209
Country United States
State California;Oregon;Washington