POTENTIAL OF IRRIGATION RESERVOIRS FOR FLOOD PREVENTION AND EVALUATION OF THE REDUCTION RATE OF FLOOD DAMAGE COST FOR EACH PREFECTURE

Abstract

 In order to grasp the potential flood prevention of the irrigation reservoir, the flood inundation model was performed for the whole of Japan assuming that the maximum reservoir capacity can work. In addition, the expected annual damage cost was calculated. As a result, the reservoirs has the potential to reduce the amount of the expected annual damage cost caused by floods throughout Japan by about 1.0 - 3.0%. The prefectures with the highest reduction effect for the expected annual damage cost were Kagawa, Hyogo, Nara, Hiroshima and Shiga prefecture, in that order. On the other hand, it was found that the Kanto districts have lower reduction effect. In some prefectures, the damage reduction rate varied as the return period of the flood.