Abstract
　The West San'in district suffered severe disasters from flood and slope failure caused by record heavy rainfall such as 93 mm (Masuda) and 91 mm (Hamada) in 1 hour, 462 mm in 11 houres and 742 mm in 3.5days (Misumi), in July 20-30, l983. This district has frequently suffered flood disasters, and this suggests to us that this area would be vulnerable to flooding.
　In order to clarify the flood characteristics in Hamada and Masuda cities, the flood runoff and inundation analysis is carried out applying the kinematic runoff model for non-inundated watersheds, and the dynamic runoff model for inundated areas with extended side sections (Hamada) or with storage tanks (Masuda), in this paper. The results explain well the flood behavior on this occasion, and suggest the existence of the weak points of the area to be improved against flood in future.

*京都大学防災研究所
Disaster Prevention Research Institute, Kyoto University