Assessment and Zoning of Landslide Hazard Using AHP Model and Fuzzy Logic Operators in Posht Tang Watershed of Sar Pole Zahab (Kermanshah Province)

Due to the hazardous nature of landslides in mountainous areas, often causes sudden damages to the morphology and also major damage to residential areas, roads, agricultural lands and other things. In this study we used AHP model in Expert Choice software also used fuzzy logic with IDRISI software for prepared landslide zoning map for “Posht Tang” catchment that located at the north eastern of district of Sar Pole Zahab in Kermanshah province. 9 parameters were selected which is related to the occurrence of landslide that comprise land use, soil, Surface deposits, precipitation, land cover, slope, geology, geomorphology and elevation. From all variables, only six variables including geology, slope, precipitation, vegetation cover, land use and height were recognized as significant layers. Frequency ratio method was used for weighting the variable class that was determined based on the landslide percent between 0 to 1. Landslide susceptibility map were prepared with J-shape membership function and Gama fuzzy operation. From this point of view, the region was divided into very low, low, moderate, high and very high classes. Also accuracy of map was accessed by QS (Quality sum). The final weight of each factor in the AHP model showed that 36% of the catchment area is located in high and very high risk. While the operator of Gama fuzzy indicated 67% of area located in high and very high landslide Zoning. Model evaluating shows Gama fuzzy 0.7 model is more accurate than AHP model in the study area.