Landslide Hazard Zonation by Using AHP (Analytical Hierarchy Process)Model in GIS (Geographic Information System) Environment(Case Study: Kordan Watershed)

摘要

Landslides are one of the critical phenomena that frequently lead to loss of human life and propertyas well as causing severe damage to natural resources. Kordan watershed located in the Alborz Province whichincluding areas that are prone to landslide. The area under investigation is located from 50°45-05°51' Eastlongitude and 35°55'-36°05' North with expansion of about 488 km2 and elevation ranges from 1320-3900 m. Thepurpose of this study is to identify factors in landslides and zonate landslide hazard of Kordan watershed usingAHP (Analytical Hierarchy Process) model in GIS environment. In this study, 4 factors, namely geology,hydrology, human and geomorphology were identified as important factors that could play an important rolein Landslide watershed. In this study, geological mapping, using topographic maps and satellite images of thestudy area and data layers of various factors including lithology, fault, land use, roads, residential areas, slopeaspect, elevation, rainfall, temperature, congestion and drainage system in GIS using ArcGIS Software has beendeveloped and weight and relative importance of each factor in landslide hazard zonation with AnalyticalHierarchy Process (AHP) were determined. Among the effective factors, sub-criteria of lithology, distance fromthe river, distance from fault, landuse and rainfall, respectively with weights 0.314, 0.219, 0.105, 0.086 and 0.054have been identified as the most important factors in the development of landslide in study area that In total,form up >75% of the total weight. The role of other factors reduces according to their weights in landslide. Thefinal cumulative map of study area was categorized into four hazard zones and classified as zone 1-4 (very lowrisk, low risk, medium risk and high risk). According to presented model and final zonation map, about34% (30 km2) of Kordan watershed area have the occurrence of high risk and about 29.16% (142.386 km2) havethe occurrence of moderate risk. As a result of the zonation performed according to the layers, most sensitiveparts of the landslides are locted in the basin quaternary deposits and the banks of rivers. The landslide hazardzonation map is useful for landslide hazard prevention, mitigration and improvement to society and properpalnning for land use and construction in the future.