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Abstract

Regional flood risk assessment is the base for a sound and comprehensive risk planning or management. The regional flood loss is the sum of the damages in all the flooded parcels. The data involved in this process are multifarious and difficult to establish and maintain especially in the developing countries that suffer most often from the flood hazard. A grid-based GIS approach to regional flood damage assessment is proposed in this paper. Aggregated census data that are relatively available were used instead of the data at parcel level. An algorithm was proposed to disaggregated these aggregated census data into spatially uniform grid cells as being used in most flood hazard simulation models. Land use or zoning information was used in the disaggregation process for capture of the realistic spatial distribution of the economic activities. The exceedance probability curve of the flood loss was used to integrate the damage assessments of individual flood event for a full probability range presentation of the flood risk. A framework was also developed for coupling the regional flood risk with the risk planning and management through the use of exceedance probability curve and annual average flood loss concepts. Shih-Jr City in northern Taiwan was used as a study area for the demonstration of the proposed algorithm

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