Physiographic Drainage-Inundation Model Based Flooding Vulnerability Assessment

Flooding vulnerability assessment is an important issue in Taiwan since Taiwan lies within the most active tropical cyclone formation zone of the Western Pacific. Huge economic damages and losses of human lives are occurred almost every year. This study aims to evaluate flooding vulnerability of a given area subject to large-scale land developments. A scoring-based approach associated with a physiographic drainage-inundation model is developed to quantitatively evaluate vulnerability for flooding. The flooding vulnerability index defined as the product of an exposure score and a hazard score. The exposure score assesses relative losses exposed to flooding, which is determined by land-uses classification. The hazard score measures flooding severity, which is simultaneously determined by inundation depth and duration that are obtained from the inundation model for a design storm. The Yenshui River basin located in southwestern Taiwan is used an example to illustrate the proposed method. The results show that the projected urbanization plan within the Yenshui River basin would increase flooding vulnerability from 0.371 to 0.472. However, this value is reduced to 0.388 when the mitigation measure has been implemented. The obtained spatial distribution of flooding vulnerability for a design storm provides decision-makers useful information to identify hotspots of the study area and evaluate effects of flood-mitigation measure on flooding risk-reduction. Copyright Springer Science+Business Media B.V. 2012