洪水による被害推定手法の高度化に関する研究

Abstract

本研究では洪水による直接被害(家屋被害，作物被害)の推定手法について述べる．基本的な考え方としては洪水氾濫シミュレーションを構造格子型で実施し，グリッドセルで出力された浸水深情報を詳細なベクトル型データに属性化することにより，家屋一棟一棟、農地一区画一区画毎の経済被害リスクの推定を可能とする．本稿では，まず，滋賀県竜王町により整備されたベクトル型データを用いた家屋・農作物被害推定手続きを紹介する．その後，佐用川流域全体を対象に構造格子で統合型の降雨流出・洪水氾濫同時解析を実施し，これによる浸水深に基づいた経済被害推定を行い，実態の経済被害と推定経済被害を比較する．本稿の経済被害推定手法の汎用性は高く，かつ構造格子型で広域の降雨流出・洪水氾濫解析の有効性を示すものである．

This paper describes a framework to estimate the direct economic damages (e.g. house and crop damages) due to floodings. The basic idea is that: (1) the flood inundation simulations are carried out with a structured grid, (2) the inundation depths output in grid cells from the structured grid are transferred to the house and crop filed vector data as attributes and (3) the economic risk of each house and crop field is estimated using the attributes. In this paper first the example of the economic damage estimation using the vector data prepared by the Ryuou Town is introduced. Then, an integrated rainfall-runoff/flood inundation simulation model with a structured grid is developed and applied to the Sayogawa river catchment which recently experienced severe flood damages due to extreme rainfall. Based on the inundation depths observed and simulated with this model as well as the actual economic loss and estimated, the accuracy of the flood and economic estimation models are investigated. This paper shows the usefulness of the economic risk framework and large-scale integrated rainfall-runoff/flood inundation model.