STUDY ON RISK DISTRIBUTION OF DEBRIS FLOW IN THE SEDIMENT DISASTER HAZARDS RESIDENTIAL AREA

Abstract

 In Hiroshima Prefeture, many houses exist in alluvial fan area near mountain side, and many of them are designated as debris flow dangerous area. In the mountainous housing area, evacuation routs are limited so when heavy rainfall occurs, it might be difficult to move outside of the designated area. Therefore, it is important to understand the dangerous risk distribution inside the designated area to consider safe evacuation planning. In this study, we conducted debris flow simulations and focued on alluvial fan housing area’ s dangerous risk distribution. In simulations, sediment volume, discharge, and lanform conditions influence the debris flow flooding and deposition. And when debris flow occurs, many houses are destroyed and landform seems to change. Therefore, we applied DEM and DSM data to consider both conditions with houses and without houses. We considered a number of scenarios for sediment volume and discharges considering from Sabo Master plan’ s method, and overlay the scenarios results and consider the disaster risk’s distribution inside the designated area.