Landslide Hazard Zonation Using AHP Model (A case study: Ayvashan damwatershed, Lorestan)

The landslide is one of the mass movement processes,which occurs in Iran and parts of the world every year. This phenomenonoften causes significant loss of life and financial damages. Therefore, this study has been carried out to identify the factors affectingthe landslide occurrence and to localize the landslide prone areasin order to investigate the landslide hazard zonation of Ayvashan Dam Watershed using the Analytic Hierarchy Process (AHP) method. At the onset of the study, some of the most important factors that influencethe occurrence of this phenomenon such as lithology, slope, precipitation, landuse, elevation, aspect, distance from drainages, and fault,as the independent variables,were prepared and digitized in the GIS software environment. Then thelandslideareas were identified viathe aerial photos and field surveys, and the landslide distribution maps of the watershedwere prepared. In the next step, through the use of the AHP method, the factors examined in the previous step were comparedin pairs,and the weight of each factor that indicates the degree of its influenceon causing the landslides of the region has been calculated. According to the results of the landslide hazard zonation using the AHP, 14.85, 33.89, 23.75, 19.54, and 7.95 percent of the area of the region are located in very low, low, moderate, high, and very high risk classes respectively.