POSTFIRE DEBRIS FLOW MODELING FROM A PRE-FIRE PLANNING PERSPECTIVE, SOUTHERN CALIFORNIA
The California Geological Survey (CGS), working with the California Department of Water Resources and the California Office of Emergency Services, is using the empirical models developed by the USGS (Cannon et al., 2009; Gartner et al., 2008) as well as southern California debris yield models (Gatwood et al., 2001; Gartner et al., 2009), to assess postfire debris yields from a pre-fire planning perspective. Modeling is being conducted on fifteen representative watersheds within five southern California counties. A range of burn percentage and rainfall scenarios are being modeled in each watershed to provide information on the potential for debris laden flows and debris flows to occur, should a watershed burn. The results from the three different models are compared with debris basin cleanout records, where available, and are provided in order to present a range of possible postfire debris yields at debris basin locations situated above populated areas. The modeling results are intended to be used by planners and floodplain managers in the development of emergency response and hazard mitigation plans.