Landslide Susceptibility Mapping in the Reservoir of Alborz Dam Using Analytical Hierarchy Process and Bivariate Statistics

Landslides cause damage to property and pose a threat even to human lives. Suitable landslide susceptibility, hazard and risk models could help mitigate or even avoid the unwanted consequences resulted from such hill slope mass movements. For the purpose of landslide susceptibility assessment, a spatial database, which included 18 landslides prepared and analyzed using LISS-IV satellite imagery and geographical information system (GIS) technology. Analytical hierarchy process (AHP), the statistical index (Wi) and weighting factor (Wf) methods were applied to determine the significance of event-controlling parameters in triggering the landslides. The parameters included lithology, slope gradient, slope aspect, elevation, distance from faults, distance from stream and drainage density. These factors are different in geomorphic and geologic setting. The result showed that lithology, slope gradient and distance to stream play most important roles in landslide susceptibility. To confirm the practicality of the three susceptibility maps, there were compared with landslides activity map containing 12 active landslides. The results showed that the Wi method gave a more realistic picture of the actual distribution of landslide susceptibility, than the Wf method in the reservoir of Alborz dam.