In our country, many peoples are killed and many houses and fields are destroyed by Debris flow every year.
So they request to do the countermeasure for Debris flow, but dangerous torrents are too much (more than 62000 torrents), so that it can not execute the countermeasure with civilengineering works for each torrent soon. Then it is need for the social countermeasure such as establishment of refuge system and control of land use.
Especially for such countermeasure, it is important to know the hazard area of Debris flow.
Usually Debris flow hazard area is studied with empirical and theoritical way, but it is difficult to generalize the hazard area by only such studies. Then author studied on the Debris flow hazerd area experimentally.
In this paper, author made clear the followings ;
(1) Experimental method is favorable as regards evaluating the effect of geomorphological condition in Debris flow deposit zone.
(2) Side step phenomena causes in some geomorphological condition and deposit length of Debris flow changes by that phenomena.
(3) Sediment volume of Debris flow has an upper limit and that value is able to be estimated.
(4) Debris flow has a harmful effect on the human life compared with Sediment flow.