2003 年 56 巻 3 号 p. 36-43
Debris flows occurred in Kyushu region due to localized rainfall which was caused by a seasonal rain front from 18th to 20th July, 2003, causing 20 dead person, 7 injured person and 63 damaged houses. Authors made investigations at Hougawachi-Atsumari district, Minamata city, Kumamoto Pref. and Sanjyou 1-choume, Dazaifu city, Fukuoka Pref., where were damaged by debris flows. In both cases, the debris flows were initiated by landslides. In order to estimate the volume of sediment discharge and velocity, authors surveyed geometry in both site. The volume of sediment discharge plunging into the village of Hougawachi-Atsumari district was estimated from about 98, 000m3 to 107, 000 m3, and the velocity of debris flow was estimated from about 2.9m/s to 23.5m/s. The volume of debris flow plunging into the village of Sanjyou 1 choume district was estimated about 12, 000m3. And the velocity of debris flow was estimated from about 4.2m/s to 14.3m/s.