How long do runoff-generated debris-flow hazards persist after wildfire?

Geophysical Research Letters
By: , and 



Runoff-generated debris flows are a potentially destructive and deadly response to wildfire until sufficient vegetation and soil-hydraulic recovery have reduced susceptibility to the hazard. Elevated debris-flow susceptibility may persist for several years, but the controls on the timespan of the susceptible period are poorly understood. To evaluate the connection between vegetation recovery and debris-flow occurrence, we calculated recovery for 25 fires in the western United States using satellite-derived leaf area index (LAI) and compared recovery estimates to the timing of 536 debris flows from the same fires. We found that the majority (>98%) of flows occurred when LAI was less than 2/3 of typical prefire values. Our results show that total vegetation recovery is not necessary to inhibit runoff-generated flows in a wide variety of regions in the western United States. Satellite-derived vegetation data show promise for estimating the timespan of debris-flow susceptibility.

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Publication type Article
Publication Subtype Journal Article
Title How long do runoff-generated debris-flow hazards persist after wildfire?
Series title Geophysical Research Letters
DOI 10.1029/2023GL105101
Volume 50
Issue 19
Year Published 2023
Language English
Publisher American Geophysical Union
Contributing office(s) Geologic Hazards Science Center - Landslides / Earthquake Geology
Description e2023GL105101, 10 p.
Country United States
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