Comparisons of different models for landslide susceptibility mapping in Zangvan watershed, Ilam province

Distinguishing the susceptible areas to landslide using different landslide susceptibility mapping (LSM) models is one of the primitive and basic works to reduce probable damages and reduce risk. The main purpose of this research is the efficiency evaluation of four methods including Information value (WINF)، Valuing area accumulation (Wa)، Analytical Hierarchy Process (AHP)، Kopta-Joshi proposed method (LNRF) for LSM in Zangvan watershed، Ilam province. At first، all the effective factors in landslide occurrence were inspected. By analyzing the parameters، nine factors including slope، aspect، elevation، precipitation، distance from road، distance from fault، distance from drainage، land use and lithology were distinguished as the effective factors in landslides occurrence in the studied area. After preparing the information of these nine factors in GIS environment، the location of landslides were determined using areal photographs and satellite images and LSM performed by the above four methods. Finally، the landslide index was used for evaluation the ability of appropriate LSM model. Based on this Index، the information value method classified more 52 percent of occurred landslides in very high danger class. Therefore، this method is more efficient and proposed as the best LSM method in the Zangvan watershed because of compatibility of landslides with high danger classes and ability of differentiation of danger classes.