Mass movements zonation and its occurrence effective factors in Ilam dam watershed

According to abundant damages and the extension of mass sliding in the country، its zonation mapping and investigating effective factors on its occurrence is necessary for preventing and control. Therefore، a research has been conducted in the Ilam dam watershed to create geologic، physiographic، Land use، vegetation cover، soil erosion، climatologic، pedologic and geomorphologic maps، using earth data layers، topographic maps، Geographic Information Systems (GIS) and field surveys. The methodology of this research has been accomplished base on distinction of geomorphologic units while using aerial photos and crossing basis maps. Then، the effective factors on mass movement occurrence were investigated using logistic regression equations. So that، the factors such as slope، geological formation، pedologic، climatic، etc. were considered as independent variables and the frequency of mass movement occurrence was considered as dependent variable. Results demonstrated that factors such as slope، geological formation، the kind and the amount of soil minerals، and land use are the most effective factors on frequency of land sliding in the watershed.