Flood Susceptibility Mapping Using a Coupled Fuzzy-AHP MCDM Approach, a Case Study of the Gadarchay River Basin

Floods are one of the most prominent threats to human life. Factors affecting a flood are rainfall, surface run-off, sea level, soil type, and regional topography. This study introduces the application of analytical hierarchy process coupled with fuzzy logic, altogether fuzzy analytical hierarchical process (FAHP), to address flood risk in Gadarchay River basin. The methodology is frequently used when access to exact numerical data, such as river bed boundaries, rainfall data, etc. is restricted or unavailable. To this end, five possible correlators of flood were used as input for the FAHP model. These input data are elevation, distance to river, population, slope and land use. They were fed into the FAHP model, and the model output was evaluated with the history of flood in two particular cities located in the basin. The results indicated that cities Naghdeh and Oshnavieh with 95% and 64% risk of flood are two of the cities with highest chance of flood with a population of 36315 and 15015, respectively.