Preparation of a flood-risk environmental index: case study of eight townships in Changhua County, Taiwan

To evaluate flood-prone areas, correlation analysis of flooding factors for the quantitative evaluation of hazard degree was determined to assist in further disaster prevention management. This study used flood-prone areas in 35 villages over eight townships (Changhua, Huatan, Yuanlin, Xiushui, Puyan, Hemei, Dacun, and Erlin) in Changhua County as research samples. Linear combination was used to evaluate flood-prone environmental indices, and an expert questionnaire was designed by using the analytic hierarchy process and the Delphi method to determine the weights of factors. These factors were then used to calculate the eigenvector of a pairwise comparison matrix to obtain the weights for the risk assessment criteria. Through collection of disaster cases, with particular focus on specifically protected areas where flooding has occurred or is likely to occur, public adaptation and response capabilities were evaluated by using an interview questionnaire that contains the items of perceived disaster risk, resource acquisition capability, adaptation capability, and environment understanding and disaster prevention education. Overlays in a geographic information system were used to analyze the flood-risk degree in villages and to construct a distribution map that contains flood-prone environment indices. The results can assist local governments in understanding the risk degree of various administrative areas to aid them in developing effective mitigation plans.