7617号台風による日下川波介川流域の水害とその考察

Abstract

The Kusaka and the Hage basins located in Shikoku District, west Japan, sufferedagain severe disasters from flood caused by record heavy rainfall accompanied with 7617typhoon, following to 7505 typhoon in August, 1975. The rain falled continuously duringthe period of September 8～13 and the areal depths in both basins amounted to 1, 019mmand 881mm, respectively.This paper discusses the flooding processes and factors relating to the disasters. Theflooding processes are analyzed to simulate hydrographs of water level observed at somepoints in both basins by the method of trial and error of computation based on themathematical models of kinematic wave for non-inundated watersheds and dynamic wavefor inundated areas. Hydrographs of flooded water level are also estimated under somehypothetical drainage facilities to suggest some means for preventing or mitigating suchthe disasters from flood.