2002 Volume 55 Issue 1 Pages 15-25
On June 29 th, 1999, Hiroshima City had localized torrential downpour and many simultaneous debris flows. After surveying the hazardous debris flows, Hiroshima Prefecture government used Guide A which was based on a conventional method to change the rainfall warning and evacuation levels. This study aims to establish more accurate method to give the warning and the information of the timing of the evacuation. As a result, we obtained that fallowing procesure is necessary to do it. First, we need to determine the spatial distribution of rainfall intensity. Second, by applying this result to statistical analysis of occurrence / nonoccurrence condition of debris flow in consideration of mountain-stream topography proposed by us previously. And this method gives much more accurate information about warning and evacuating than present method.
