Journal of the Japan Society of Erosion Control Engineering, Vol.58,No.6,2006
A study based statistical method on the relationship between occurring sediment‐related
disasters on June 29 1999 at the west part of Hiroshima prefecture and rainfall,
geographical and geological factors
Hiroyuki OHISHI Toshio YAGI Hiroaki TAKEMOTO Yoshinori ARAKI Hiroyuki SAKAKIBARA Kohei FURUKAWA Makoto URA
Abstract
The western part of Hiroshima Prefecture suffered from a large scale disaster with heavy rainfall on June 29, 1999. This area suffered from a heavy damage in this disaster in which 24 lives were lost and 64 houses completely destroyed. In this area, there is something in common between the geographical and geological features. And if the same condition is met, it is assumed to suffer the same disaster. However, in this kind of disaster, the situations at Hiroshima City and Kure City are very different though both cities are in the same western part of Hiroshima Prefecture. Against the 155 debris flows which occurred at the western part of Hiroshima City; Saeki, Asakita, Asaminami Ward, only few debris flow occurred at Kure City, regardless of being a neighboring city to Hiroshima City. On the other hand, more slope failures occurred mainly at Kure City while only few occurred at the western part of Hiroshima City. These differences of occurring disaster are considered to be caused by the difference of rainfall or geographical and geological features between the western part of Hiroshima City and Kure City. In this study, we analyzed the differences of these factors between the 2 cities through the statistical method, Willcoxon test, in which we tried to make clear relationship between occurring disaster (debris flow and slope failure) and rainfall as well as the geographical and geological features.
Key words: deblis flow, slope failure, Willcoxon test, statistical method
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