A STUDY OF THE METHOD OF FLOOD INFORMATION PRESENTATION FOR EARLY PRE-DISASTER PREVENTION ACTION -FOCUSING ON THE DOWNSTREAM BASIN OF ARAKAWA RIVER-

Abstract

 Pre-disaster prevention actions such as wide-area evacuation is being considered in the downstream basin of Arakawa River, and it is necessary to forecast flooding for several days ahead in order to achieve steady implementation. However, uncertainly in flood forecasting is not clear, and it is difficult to determine the implementation of pre-disaster prevention actions based only on specific prediction values. Therefore, this paper focuses on observed rainfall pattern as indicators for evaluating uncertainty and presents the method of flood information presentation which indicates the occurrence frequency of the water level for arbitrary rainfall by flood forecasting using rainfall amount extended to arbitrary rainfall. In addition, it is confirmed that this method can be applied even when the actual rainfall is exceeded by comparing it with the occurrence frequency of the water level by flood forecasting using large-ensemble information of the rainfall by d4PDF.