INVESTIGATION ON FLOOD DISASTER OF THE RIVER IGA IN AUGUST 2008

Abstract

Flood disaster occurred along the River Iga, Okazaki, Japan, in August 29, 2008. Two people died by this disaster; one is by overflow into resident area and another is by destroying a house in river area between banks. Precipitation data and flood phenomena are investigated and analyzed by data collection and field survey after the event. Results shows; (1) maximum average hourly rainfall intensity is 108.8mm/hr and more than a half of quantile removed from river by overflow due to lack of cross-section area in upstream river channel. (2) A part longitudinal part has narrow cross-section, which has more than 60 houses in river area between river banks, rose up water levels upstream side, and heavy overflow disaster occurred due to water level propagation up to 400m upstream.