2004 Volume 56 Issue 6 Pages 20-26
Debris flows recurred on August 8 th 2003 in Fujiwara town, Mie prefecture where debris flows have occurred in 2002 since occurring in 1999. The debris flows occurring at Nishinogaito stream and Kotaki-stream, were trigged by the 10 th typhoon which caused total rainfall 333mm, maximum hourly rainfall 43mm and maximum 10-minute rainfall 19mm. The debris flows may occur when the maximum 10-minute rainfall was recorded because of response of debris flow sensors. By the field survey, it is revealed that sediment deposition at uppermost gravel sediment zone was eroded, and accumulated as results of the behavior of flow at midstream. At Nishinogaito stream, especially, an unstable sediment deposition still remains.