Study on debris flows risk distribution with simulations applying different Digital Elevation Model data for evacuation planning

Abstract

Debris flows simulations are useful for evacuation planning but they are not applied widely because the initial setting such as debris flow scale and landform affect the results but setting conditions seems to be complicated. In this study, we focused on DEM (Digital Elevation Model) landform data with 5 m mesh provided from Geospatial Information Authority of Japan (GSI) and DEM data acquired from LiDAR with high resolution, which are widely used in Japan. We conducted simulations on housing area in Hiroshima which have experienced debris flows events in 2014 and in 2018. We also conducted simulation on farming area which has not experienced debris flow recently but designated as hazard area from local government. For disaster cases, results using LiDAR DEM data and also considering the houses can describe the influence area and high risk area around the valley exit, and also can describe locally dangerous area and debris flow moving on roads. For farming area, LiDAR DEM can describe the field area deposition comparing with GSI DEM, but didn't show remarkable difference for considering houses. To consider detailed evacuation planning such as safe evacuation routs and shelters, applying high resolution LiDAR DEM data and considering houses for housing area will be useful.