Effects of Large Wildfire Burned Scars on Downstream Flood Discharge in California Watersheds: A Hydrological Modeling Study

This study investigates the impact of wildfires on extreme floods in the Upper Cosumnes watershed of California, affected by the Caldor Fire of 2021. Using a novel approach that incorporates curve number (CN) increments to reflect post-fire conditions, we compare probable maximum flood (PMF) estimates with and without wildfire effects. Results demonstrate that the PMF considering wildfire impacts is 5.23% greater than the traditional PMF estimate. This significant increase highlights the critical need to incorporate wildfire effects in extreme flood estimations, especially given the increasing likelihood of compound disasters in a changing climate. Our findings underscore the importance of adapting flood risk assessment methodologies to account for the cascading impacts of wildfires on hydrologic responses in fire-prone regions.