Study of Slope Stability in Watershed Basin of Eivashan Dam Using GIS

Watershed basin of Eivashan with an area of 12315 hectares is located in Khorramabad sub region of Lorestan province in Iran، between 48° 48´ to 48 50´ longitude and 33° 22´to 33° 29´ latitude. 5 different methods including Nilsen، Revised Nilsen، Bivariate statistical analysis (compaction of level)، expert judgment and mora varson''s initiative methods are used to derive landslide hazard zonation maps in this region sing GIS. The results shows that Nielsen modified and expert judgment wok better than other methods in evaluating landslide phenomena in the study area. Other methods can not accurately due to low land areas، sliding and damping factors is the failure of the geology and rainfall.