2009 Volume 15 Pages 61-66
In the afternoon of July 28 in 2008, there occurred a flash flood in the Toga River due to localized torrential rain and tragically caused five fatalities including children. The water level allegedly rose about one meter in ten minutes and there seemed to be little time remained to escape from the site. In order to clarify the cause of this disaster, hydrological information such as time variations of local rainfall distribution and river discharge is indispensable. This research pays attention to the flow phenomena within the river channel by estimating the peak flow discharge from video images and performing a two-dimensional flow simulation utilizing laser scanning data for representing complicated river bed topography. It was made clear from the video analysis that the peak discharge is within the range between thirty and forty cubic meters per second. Moreover, the numerical simulation using the appropriate roughness coefficient can reproduce the detailed flow situation, from which it becomes possible to produce CG animations for educating people about the danger of flash flood.
