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Landslide susceptibility mapping using the fuzzy gamma operation in a GIS, Kakan catchment area, Iran
Majid H. Tangestani
Dept. of Earth Sciences, Faculty of Sciences, Shiraz University, 71454 Shiraz, Iran
Tel: +98 711 2284572, Fax: +98 711 2280926, E-mail: tangestani@geology.susc.ac.ir
Abstract
Northwestern Fars province, Iran, is prone to landslides. In order to help the planners for selecting suitable locations to implement development projects a landslide susceptibility map was produced for the Kakan catchment area using the gamma operation of the fuzzy approach. Lithology, slope angle, slope aspect, land cover, weathering depth, proximity to roads, topographical elevation, and soil depth were considered as landslide causal factors for the study area. The factor maps were input into GIS and landslide hazard evaluation factor (LHEF) rating and fuzzy membership functions were assessed for each class of the factor maps. A weighting factor was then considered for each factor map and multiplied to fuzzy membership functions to justify the affect of each data layer on the output fuzzy membership functions due to the expert’s opinion. Three values for gamma were examined and output maps were evaluated using the known landslides. A gamma value of 0.94 yielded the most reliable susceptibility for landslides. Comparing the known landslides of the area with the output susceptibility map showed that the identified landslides were located in the high susceptibility zones.
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