Temporal changes in rainfall intensity–duration thresholds for post-wildfire flash floods in southern California

Abstract. Rainfall 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 generate floods as landscapes recover from fire, but there little guidance on how change a function time since fire. Here, we force hydrological model with radar-derived precipitation estimate ID for post-fire in 41.5 km2 watershed southern California, USA. Prior work this study area constrains temporal changes parameters, allowing us thresholds. The results indicate that increase by more than factor 2 year 1 5. Thresholds based averaging intensity over durations 15–60 min perform better those average shorter intervals. Moreover, the 75th percentile 25th or 50th intensity. Results demonstrate models can be following disturbance and provide metrics best suited predicting floods.