降雨観測データの土石流発生予測への適用 : 広島県における最近の事例を使って
KJ00000197479.pdf 1.87 MB
Application of the observed rainfall data to the prediction of debris flows : A case study with the recent debris flow disaster in Hiroshima
A large number of debris flows occurred in Hiroshima Prefecture on June 29 and September 15,1999. The rainfall events as the cause of disasters were characterized in the point of extreme localization and intensity. Recently, such type of disasters has been often reported and in most of cases, the relationship between the rainfall situation and the occurrence of the debris flow disaster could not be grasped well with a rainfall observation system. We have considered the validity of this current system with some intense rainfall events and found some problems in it. One of the important points is that the observed rainfall value was not always the value of the site of the disaster. Also, several problems concerning the evaluation method of the past rainfall might be pointed out. As another very important point, we could indicate that the flow of the information transmission system was one way and that it did not function in too many necessary sites. A lot of damaged people could not have imaged a debris flow nor slope failure before the disaster. So we tried to establish an improved system. In our proposed system, the past rainfall is stored in each small district with the interpolation method. As the effect of the past rainfall on the point decreases with time, the sum is computed with a supposed attenuation constant. As the result, the rainfall situation calculated in this system is preferable to the currnet one to evaluate the possibility of debris flow. The calculation in this proposed system is not too heavy for the public to perform it with a personal computer. We can therefore expect that it contributes to increase the number of interested citizens in disaster and its prevention.
広島大学総合科学部紀要. IV, 理系編