Rainfall intensification amplifies exposure of American Southwest to conditions that trigger postfire debris flows

npj Natural Hazards
By: , and 

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Abstract

Short-duration, high-intensity rainfall can initiate deadly and destructive debris flows after wildfire. Methods to estimate the conditions that can trigger debris flows exist and guidance to determine how often those thresholds will be exceeded under the present climate are available. However, the limited spatiotemporal resolution of climate models has hampered efforts to characterize how rainfall intensification driven by global warming may affect debris-flow hazards. We use novel, dynamically downscaled (3.75-km), convection-permitting simulations of short-duration (15-min) rainfall to evaluate threshold exceedance for late 21st-century climate scenarios in the American Southwest. We observe significant increases in the frequency and magnitude of exceedances for regions dominated by cool- and warm-season rainfall. We also observe an increased frequency of exceedance in regions where postfire debris flows have not been documented, and communities are unaccustomed to the hazard. Our findings can inform planning efforts to increase resiliency to debris flows under a changing climate.

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Publication type Article
Publication Subtype Journal Article
Title Rainfall intensification amplifies exposure of American Southwest to conditions that trigger postfire debris flows
Series title npj Natural Hazards
DOI 10.1038/s44304-024-00017-8
Volume 1
Year Published 2024
Language English
Publisher Nature
Contributing office(s) Geologic Hazards Science Center - Landslides / Earthquake Geology
Description 14, 10 p.
Country United States
State Arizona, California, Nevada, New Mexico, Utah
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