Statistical and Simulation Models for Mapping Debris-Flow Hazard

We describe two different GIS-based approaches to the delineation of debris-flow hazard. The first is empirically based, and uses logistic regression to predict sites of rainfall-induced shallow landslides that initiate debris flows in San Mateo County, California. The second is both empirically and process based, and uses multiple physically-based simulations of debris flows to evaluate hazard downslope from initiation sites in Honolulu, Hawaii. The two approaches use fundamentally different data to delineate hazard in fundamentally different ways, and are described here as contrasting examples of approaches to hazard delineation.