FLOOD HAZARD ASSESSMENT USING FUZZY ANALYTIC HIERARCHY PROCESS: A CASE STUDY OF BANG RAKAM MODEL IN THAILAND

摘要

Flood is a natural hazard with the highest frequency and the widest geographic distribution across the globe that generally affects people's lives and the ecosystem, causing catastrophic disasters. Flood is the most fatal and frequent in Thailand, where people are affected annually. In 2011, Thailand has experienced the worst flood, which makes the floods one of the top five significant natural disaster events in modern history. Therefore, the flood hazard assessment is a fundamental pre-requisite for flood risk assessment. In this study, the combination of Fuzzy Analytic Hierarchy Process (Fuzzy AHP) based on Chang's extent analysis (Chang, 1996) and Geographical Infonnation Systems (GIS) were used to assess flood hazard by comparison the elevation effects between from Shuttle Radar Topography Mission Digital Elevation Model (SRTM DEM) and Light Detection and Ranging (LiDAR). The study area is "Bang Rakam Model 60" project. Designed as a retention area for the Yom river, this project was launched by the Royal Irrigation Department (RID) as a guideline model to solve flood problems for the central region and Bangkok. Eight factors were considered for flood hazard assessment including 1) distance from drainage network 2) drainage density 3) elevation 4) flow accumulation 5) land use 6) slope 7) soil water infiltration 8) average annual rainfall. Each factor was weighted to obtain the final flood hazard map. The accuracy of the method has been validated with the repeated floods area data, which is the product from the Geo-Informatics and Space Technology Development Agency (GISTDA). The very high flood hazard areas were found near the drainage network. Important supporting factors to flood hazard are flow accumulation, elevation, and soil water infiltration (same weights), distance from drainage network, average annual rainfall, drainage density, land use, and slope, respectively.