Abstract
This paper examines the extraction of sediment disaster hazard area and the precipitation criteria for which evacuation is required. The past sediment disaster cases in Nagano prefecture are analyzed by using precipitation information and regional characteristics data such as topographic features, geology and land use data, and the debris flow hazard areas are extracted. The relationship between the precipitation and the disaster occurrence in the past debris flow disasters is investigated, and then the rainfall criterion for judging the risk of sediment disaster is derived.
