Zoning the Risk of Landslides in Badranlou Basin Using the Analytic Network Process (ANP)

The present study is to identify the potentiality of the landslide occurrence in Badranlou Basin with the area 300.37 Km2. To prepare the risk map of landside, firstly using conducted studies, a total number of 69 landslides were identified in this basin which covers about 243900 m2. Then, factors affecting landsides in the basin were investigated and eight factors including features of lithology, land use, the steep slope degree, the steep slope orientation, average annual rainfall, distance from waterways, distance to faults, and distance from residential centers were selected as effective factors. These factors were prioritized using expert ideas and the ANP, and then the maps related to factors affecting landside occurrence were prepared. By merging the maps related to the factors to which the coefficients calculated based on priority and valuing were applied in the ANP, at last the map of the landslide risk in Badranlou Basin was prepared and the studied region was classified into three classes in terms of landside occurrence accordingly, %30.43 of the region is faced with moderate-level risk, %37.68 of them with high-level risk, and %31.89 of it is faced with very high-level risk. After that, to evaluate the conducted zoning, the comparison of the final zoning map with the map of dispersion of landslides was conducted and the results indicated that 21 landsides occurred in area 75600 m2 in the landside points with moderate-level risk, 26 landsides occurred in area 91800 m2 in landside points with high-level risk, and 22 landsides occurred in area 76500 m2 in landside points with very high-level risk. Furthermore, the results indicated that the most important factors affecting the occurrence of landsides in the basin includes the degree of steep slope, lithological features, distance from waterways, and average annual rainfall.