Hazard assessment for post-wildfire debris flows, which are common in the steep terrain of the western United States, has focused on the susceptibility of upstream basins to generate debris flows. However, reducing public exposure to this hazard also requires an assessment of hazards in downstream areas that might be inundated during debris flow runout. Debris flow runout models are widely available, but their application to hazard assessment for post-wildfire debris flows has not been extensively tested. I will discuss a study in which we apply three candidate debris flow runout models in the context of the 9 January 2018 Montecito event. We evaluate the relative importance of flow volume and flow material properties in successfully simulating the event. Additionally, I will describe an in-progress user needs assessment designed to understand how professional decision makers (e.g., county emergency managers, floodplain manager, and Burned Area Emergency Response team members) might use post-fire debris flow inundation hazard assessment information.
Katy Barnhart is a Research Civil Engineer at the U.S. Geological Survey’s Geologic Hazards Science Center. She received her B.S.E. (2008) in Civil and Environmental Engineering from Princeton University and her M.S. (2010) and Ph.D. (2015) in Geological Sciences from the University of Colorado at Boulder. Her research uses numerical modeling to understand past and forecast future geomorphic change on a variety of timescales.