The rainfall intensity-duration control of debris flows after wildfire

Geophysical Research Letters
By: , and 



Increased wildfire activity in the western United States has exposed regional gaps in our understanding of postfire debris-flow generation. To address this problem, we characterized flows in an unstudied area to test the rainfall intensity-duration control of the hazard. Our rainfall measurements and field observations from the northern Sierra Nevada (California, USA) show that debris flows resulted from a short burst rainfall during a low-accumulation storm. In contrast, a much higher accumulation storm (∼10 times more rainfall) with lower short-duration rainfall rates only produced low-hazard flooding. We conclude that total storm rainfall is not an ideal metric for identifying the rainfall conditions that initiate runoff-generated debris flows in the first year after wildfire. Rather, a focus on short-duration (<1 hr), high-intensity rainfall that can occur during localized thunderstorms, or bands of intense rainfall during prolonged rainstorms, is more beneficial for the purposes of hazard assessment and warning.

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Publication type Article
Publication Subtype Journal Article
Title The rainfall intensity-duration control of debris flows after wildfire
Series title Geophysical Research Letters
DOI 10.1029/2023GL103645
Volume 50
Issue 10
Year Published 2023
Language English
Publisher American Geophysical Union
Contributing office(s) Geologic Hazards Science Center
Description e2023GL103645, 10 p., Data Release
Country United States
State California
Other Geospatial North Fork Feather River Canyon
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