Landslide Hazard Zoning using Gamma Fuzzy Operator, with a Case Study of Haraz Watershed

Research aimed at showing element weight used fuzzy sets because of the limitation on the use of numbers. The benefit of this theory includes the range of numbers with an accompanying possibility of the degree of landslide that can be used instead of one number. Thus, when the fuzzy collections theory is used for presenting weight factor, certainly a number is cannot determined for weight, but the only possible correct numbers provided more than other numbers may be close to correct its intended. The aim of this study was to supply landslide hazard zoning using gamma fuzzy operator in Haraz watershed. To achieve this objective, each factor having an impact on landslide occurrence - such as slope, aspect, elevation, lithology, land use, distance of road, distance of drainage, distance of fault and precipitation – were digitally mapped in a GIS environment. Landslide points were recognized using air photography and extensive field study and the level of correlation between each effective parameter in landslide occurrence with landslide points was determined using the frequency ratio model; fuzzy values were then determined using scientific ideas and a fuzzy membership function was obtained for each effective parameter in an Idrisi software environment. In this research for analysis we used different values of gamma. The results showed a gamma fuzzy operator with value l = 0.975 had best accuracy in making a landslide hazard susceptibility map in study area.