STUDY ON AN EVALUATION METHOD OF INITIATION ROBABILITY OF DEBRIS FLOWS DURING HEAVY RAINFALL

Abstract

 In recent years, debris flow due to heavy rainfall has been frequent. In addition, the large amount of sediment is transported by debris flow flows into rivers, causing sediment-flood inundations with increasing damage. In the heavy rainfall in July 2018, it rained for a long time and over a wide area, and debris flows occurred at many places in Hiroshima prefecture. The existing earth and sand disaster alert information has not taken into consideration of rainfall on each slope and topographic and ground information. The spatial grasp of debris flow occurrence and quantitative risk assessment has not been established yet. In order to solve this problem, in this paper, the rainfall data of XRAIN with good spatial resolution and the feature of the slope failure site were examined for each mountain slope during heavy rainfall events. This paper also discussed the reliability of rainfall index R’ to the heavy rainfall with strong long-term precipitation in July 2018, which is different from previous disasters due to the heavy rainfall with strong short-term precipitation, such as August 2014 and June 1999.