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Emergency assessment of post-fire debris-flow hazards for the 2013 Powerhouse fire, southern California

October 18, 2013

Wildfire dramatically alters the hydrologic response of a watershed such that even modest rainstorms can produce dangerous flash floods and debris flows. Existing empirical models were used to predict the probability and magnitude of debris-flow occurrence in response to a 10-year recurrence interval rainstorm for the 2013 Powerhouse fire near Lancaster, California. Overall, the models predict a relatively low probability for debris-flow occurrence in response to the design storm. However, volumetric predictions suggest that debris flows that occur may entrain a significant volume of material, with 44 of the 73 basins identified as having potential debris-flow volumes between 10,000 and 100,000 cubic meters. These results suggest that even though the likelihood of debris flow is relatively low, the consequences of post-fire debris-flow initiation within the burn area may be significant for downstream populations, infrastructure, and wildlife and water resources. Given these findings, we recommend that residents, emergency managers, and public works departments pay close attention to weather forecasts and National-Weather-Service-issued Debris Flow and Flash Flood Outlooks, Watches, and Warnings and that residents adhere to any evacuation orders.

Citation Information

Publication Year 2013
Title Emergency assessment of post-fire debris-flow hazards for the 2013 Powerhouse fire, southern California
DOI 10.3133/ofr20131248
Authors Dennis M. Staley, Gregory M. Smoczyk, Ryan R. Reeves
Publication Type Report
Publication Subtype USGS Numbered Series
Series Title Open-File Report
Series Number 2013-1248
Index ID ofr20131248
Record Source USGS Publications Warehouse
USGS Organization Geologic Hazards Science Center

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