RIVER STOPPAGES IN THE MIMI RIVER BY EARTH AND SAND, DRIFTWOOD AT THE TYPHOON 0514 AND PREVENTIVE MEASURES

Abstract

The typhoon 0514 hit the Kyushu area on Sep., 2005 and brought quantities of rainfall to the Miyazaki prefecture, in particular, the Mimi River Basin, where the most cumulative rainfall during 3 days was more than 1900mm. Consequently the serious damage resulted from floods and landslides. In addition, much driftwood increased the flood damage. The mountainside collapse built the natural dam which stopped the flood and impounded water upstream. In this paper, we suggest to promote the research on driftwood and propose to build dams with holes, which can control floods to avoid the serious flood damage occurred by the collapse of natural dam.