Debris flows occurred in August ‚Q‚O‚P‚U in Sounkyo, Kamikawa Town, Hokkaido

Nobutomo OSANAI, Shin]ichiro HAYASHI, Takahisa FURUICHI, Takeshi FUJINAMI, Takaaki ABE, Tadahiko TANAKA, Keitaro YOSHIKAWA, Takamitsu IPPOSHI, Keiko IWAKURA, Tomoya HAYAKAWA, Akira MATSUOKA, Norihiro NAGANO, Atsushi SAITO, Chiharu OSHIMA

Three typhoons (T7, 11, 9) struck Hokkaido within one week in August 2016. Heavy rain brought by the typhoons induced debris flows and sediment transport along the Kurodakesawa river and Shogakkonosawa in Sounkyo, Kamikawa Town, Hokkaido. Monitoring cameras for debris flows recorded the events, which provided an opportunity to describe some features of the debris flows and sediment transport. We also conducted ground and air (UAV) survey right after the series of events to supplement the monitored data. This article documents the rainfall record, geologic and geomorphic settings of the area and the monitored and surveyed data of the debris flows and sediment transport. We also report a rapid analysis of the monitored and surveyed data on sediment sources and sinks, sediment materials (type of rocks, sizes and distribution), depositional features, flow velocity and discharge. It was clear that check dams and training channel protected residential area and hotels located in Sounkyo hot spring area.

Key wordsFHokkaido, Debris flow, Check dams, Early warning