Development of a Framework for the Flood Economic Risk Assessment Using Vector GIS Data

This paper proposes a flood economic risk assessment framework using vector GIS data, expressing individual house and paddyfield, prepared by a municipal Japanese government. Flood inundation is first simulated with a structured grid, then the simulated flood inundation depth, expressed in grid cells, is assigned to vector data house and paddyfield polygons as attributes. Flood-damage ratios of houses and paddy-fields are then calculated using relationships of the flood depth, duration, and damage ratio opened by the Japanese Ministry of Land, Infrastructure, Transport, and Tourisms (MLIT). Economic loss involving building and paddyfield damages due to flooding is then calculated by multiplying the damage ratio, evaluation price per area, and the asset area. The advantage of using such vector data is that it yields the area of each house and paddyfield precisely, which also realizes, on average, the precise economic loss estimation. As the results, the spatial distribution of economic loss on an individual house/paddyfield scale is also identified. Since vector data shows area characteristics, the framework proposed here is useful in community-based flood management. A workshop presenting the framework showed that the system potentially induces workshop participants to consider community-based flood hazard management.