Zonation of Debris Cones and Talus Slopes in Aghlaghan Chay Basin (South Western Slope of Sabalan Mountain)

Debris cones are the form of slope materials, especially in mountainous areas that were streak rapid and dangerous. Because of existence more weathered volcanic rocks, mountainous topography; climatic conditions with high temperature fluctuating and large number of frost days and tectonic forces activity, Aghlaghan basin have greater potential for Debris cones and Talus slopes mass movement is very active. Therefore, Debris cones and Talus slopes are considered as the most important factors in enhancing the sedimentation in rivers. The occurrence of these phenomena every year, leads to severe soil erosion and filling Yamchi dam, in the lower part of basin. The purpose of this study is the assessment and zonation of Debris cones and Talus slopes. In this study, at first, we investigated eleven Debris cones and Talus slopes risk factors in the region. These factors are: slope, aspect, lithology, distance from roads, distance from drainage, distance from fault, rainfall, number of frost days, temperature fluctuating, land use and soil. Then data layers were prepared by GIS. Analysis and modeling was performed by using the Vikor model as one of the multi-criteria decision analysis. Eventually zoning map was prepared on 5 classes very high to very low risky. According to zoning map, 2761.72 and 7854.30 hectares of area located in categories of very risky and high risk, respectively. Most risk areas are located in the weathered volcanic formations, between 35 to 30 percent slopes, slopes with low vegetation and overlooking the valley.