Topographical criteria for the occurrence of landslides causing debris flows in the 2017 torrential rain in northern Kyushu, Japan

Abstract

In the volcanic rock fields around Hita City, 19 landslides occurred in the 2017 torrential rains in northern Kyushu, 11 of which triggered debris flows. In order to mitigate debris flows disasters caused by landslides, it is important to assess the points where landslides are most likely to occur. Therefore, topographic profiles of landslide and non-landslide slopes were calculated from digital elevation models obtained before the disaster. The results indicate that there is a topographic criterion for landslide occurrence in the relationship between the topographic position index (TPI) and the tangent Laplacian.