PRE-FIRE ASSESSMENT OF POST-FIRE DEBRIS FLOW SUSCEPTIBILITY THROUGH LONG-TERM FIRE SEVERITY FORECASTING IN THE CARMEL RIVER WATERSHED, CALIFORNIA, USA

Wildfire is a powerful hydrologic and geomorphic disturbance in steep mountainous areas such as the Central Coast Region of California. The increased intensity of wet and dry seasons brought on by climate change creates an environment which is more prone to extreme wildfire and post-fire hazards such as debris flows generated by rainfall-runoff events. In the Carmel River Watershed located in California, USA, post-fire debris flows exacerbated by such weather events could have deleterious effects on in-stream conditions, public safety, and infrastructure. Much of the Carmel River falls within a wildland-urban interface (WUI) containing aquatic endangered species such as steelhead trout and the red-legged frog. More studies are needed to document future debris flow risks in order to understand hazards prior to wildfire. To better prepare for post-fire debris flow events, we develop a predictive framework for spatially-distributed indices of how ongoing and future fire regimes and post-fire erosion may impact watershed health and WUI hazards in the Carmel River Watershed. Our work aids in understanding how fuel loading and climatic gradients control fire and post-fire hazards. While the Carmel River Watershed’s upper basin has experienced burns dating back to 1985, the lower basin remains unburned and heavily vegetated due to infrequent fire weather conditions and urbanization. With no historical fire data present for the lower Carmel basin, our work could inform predictions for how this region may burn in the future. By creating a predictive fire severity indicator and identifying potential hazard zones, we both inform the public of hazards in their area and aid management decisions for preventative planning.