Temporal changes in rainfall intensity-duration thresholds for post-wildfire flash floods in southern California
AffiliationDepartment of Geosciences, University of Arizona
Department of Hydrology and Atmospheric Sciences, University of Arizona
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CitationLiu, T., McGuire, L. A., Oakley, N., & Cannon, F. (2022). Temporal changes in rainfall intensity-duration thresholds for post-wildfire flash floods in southern California. Natural Hazards and Earth System Sciences.
RightsCopyright © Author(s) 2022. This work is distributed under the Creative Commons Attribution 4.0 License.
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AbstractRainfall intensity-duration (ID) thresholds are commonly used to assess flash flood potential downstream of burned watersheds. High-intensity and/or long-duration rainfall is required to generate flash floods as landscapes recover from fire, but there is little guidance on how thresholds change as a function of time since fire. Here, we force a hydrological model with radar-derived precipitation to estimate ID thresholds for post-fire flash floods in a 41.5ĝkm2 watershed in southern California, USA. Prior work in this study area constrains temporal changes in hydrological model parameters, allowing us to estimate temporal changes in ID thresholds. The results indicate that ID thresholds increase by more than a factor of 2 from post-fire year 1 to post-fire year 5. Thresholds based on averaging rainfall intensity over durations of 15-60ĝmin perform better than those that average rainfall intensity over shorter time intervals. Moreover, thresholds based on the 75th percentile of radar-derived rainfall intensity over the watershed perform better than thresholds based on the 25th or 50th percentile of rainfall intensity. Results demonstrate how hydrological models can be used to estimate changes in ID thresholds following disturbance and provide guidance on the rainfall metrics that are best suited for predicting post-fire flash floods. © Copyright:
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Except where otherwise noted, this item's license is described as Copyright © Author(s) 2022. This work is distributed under the Creative Commons Attribution 4.0 License.