<p> Assessment of Sedimentation Hazards in Advance of Wildfire for Hazard Mitigation Planning in Southern California</p><p>Jeremy T. Lancaster CEG, Solomon McCrea, CFM, and William R. Short CEG California Geological Survey, 801 K Street MS 12-32, Sacramento, CA 95814</p><p>ABSTRACT Assessment of post-fire runoff in areas recently burned by wildfire is an essential element of hazard recognition and mitigation. Methods range from regional scale studies to site-specific investigation, where ideally assessments are completed prior to seasonal rainfall. Regional assessments provide valuable information for local and state officials developing hazard mitigation strategies and preparing emergency response and recovery plans. Site-specific investigations identify local conditions with the intent of addressing potential impacts to specific values at risk. Significant research developments have occurred in the past decade that address regional scale post-fire runoff hazards with the intent of providing information to agencies responsible for floodplain management and public safety decisions. </p><p>In this study, the California Geological Survey (CGS) utilizes existing regional scale predictive models to assess the effects of post-fire runoff from a pre-fire planning perspective. CGS identified twenty southern California watersheds in Santa Barbara, Ventura, Los Angeles, San Bernardino, and Riverside counties situated near populated areas with residential and commercial infrastructure values at risk to the fire-flood sequence. A multiple model approach is used to assess watershed response under a range of possible rainfall and burn conditions and provides data that may be used to inform floodplain managers and emergency response personnel, should a watershed be subject to the fire-flood sequence. The results of the multiple model approach are discussed in the context of watershed physiography, geology, and historic fire and flood history. This study is conducted through the Federal Emergency Management Agency’s Hazard Mitigation Grant Program (5% initiative), administered through the State of California, Governors Office of Emergency Services in collaboration with California Department of Water Resources.</p>