Flood Susceptibility Mapping in Densely Populated Urban Areas Using Mcdm and Fuzzy Techniques

Flood, as the most destructive natural phenomenon in Iran, causes a multitude of deaths and financial losses every year in different parts of the country. This study sought to determine flood-prone areas in one of the Ajay River sub-basins (Lighvan River basin), Iran using Analysis Hierarchy Procedure (AHP) for ranking, fuzzy logic (FZ) for integrating with AHP in order to rank and Weighted Linear Combination (WLC) for the combination of maps. For this purpose, the geomorphologic and hydrologic factors affecting the occurrence of floods such as slope, distance from the river, Hydrological Soil Group (HSG), Curve Number (CN), runoff, lithology, land use, drainage density, Gravilius coefficient in each of the 23 sub-basins were considered based on the literature. The desired criteria and sub-criteria were weighted by the AHP and FZ, respectively. Then, WLC aggregation method was applied to generate the flood susceptibility map in five classes. The results earned by the combination of Multi-Criteria Decision Analysis (AHP and WLC)-FZ (MCDM-FZ) show that 28% of the area is in high and very high hazard classes that these areas are located almost at the entrance of Tabriz city, which is a densely populated urban area. Basic measured need to be taken in the upstream of the basin especially in areas with the high flood zone.