抄録
A total rainfall of 600 mm or more fell from September 4th to 6th, 2005 during typhoon Nabi, resulting in many slope failures and debris flows in Kagoshima prefecture on the Osumi peninsula. This sediment-related disaster killed five people and caused considerable damage. In this paper, to clarify the conditions of slope failures, we conducted a field investigation of the volume of trees felled by slope failures and the movement of the driftwood carried by debris flows due to typhoon Nabi in the Kawasaki river basin of the city of Tarumizu in Kagoshima prefecture. Five slope failures in the basin at an altitude below 250 m were identified as being due to typhoon Nabi. All were shallow landslides. Slope failures occurred on steep slopes consisting of a sedimentary rock base covered with volcanic ash and pumice. The area of slope failure ranged from 150 m2 to 4800 m2. Of the 379.4 m3 total volume of trees felled by slope failures, 288.1 m3 was conifer and 91.3 m3 was broadleaf trees. The driftwood budget shows that of the 379.4 m3 total driftwood, 219.8 m3 was caught by check dams, 128.0 m3 was caught in the channel and 31.6 m3 was caught in the slope failure scars.
https://ror.org/03ss88z23 
