2006 年 26 巻 4 号 p. 318-323
Typhoon 200310 (Etau) caused concentrated heavy rain in the Hidaka district of Hokkaido, Japan, in August 2003, and large-scale landslides occurred in the region, especially in the Appetsu River basin (ca. 29, 000 ha). The landslides destroyed large areas of forest on hillsides, and a huge amount of timber was carried downstream, seriously damaging the economy and affecting people's lives along the river. To prevent secondary disasters and institute prompt measures for recovery of the watershed, we applied remote-sensing techniques using aerial photographs and satellite images to estimate the distribution and area of the landslides. The total area of landslides resulting from the typhoon was estimated to be 397 ha in the Appetsu River basin, constituting 1.7% of the total forest area in the basin. The total stem volume of timber destroyed by the landslides was estimated to be 57, 100m3.