Mapping Landslide Hazard Zonation in Great Karoon Aquifer Basin by Analytical Hierarchy Process (AHP) model in Geographic Information System (GIS) Environment Print

We have done this research in order to study frequency and transmissivity on big and widespread landslides in Great Karoon aquifer basin due to establish Great Karoon no 1,2,3 dams Purpose of this research is mapping landslide hazard zonation in Conformity with the new area activities and changes after: 1. Dams establishment, 2. land cover changing due to irrigation, drainage, river branches and irrigation canals. 3. Topography change of the zone due to harvest, moving huge amounts of soil and excavation process. In this research after considering previous researches and library studies we have found out 8 effective factors as essential items in occurring landslides: slope, altitude, rainfall, and distance from road, distance from fault, and distance from drainage basin, land cover and petrology. Then we made information layers of these factors by using Arc GIS9.3 softwares in GIS environment. after it we allocated classe's weight of every factor by using Analytical Hierarchy Process (AHP) method. We made ultimate map by compounding the different layers, and then categorized it in 4 classes; extremely hazardous, fully hazardous, middle hazardous and less hazardous. The extremely hazardous zones are affected by area geology conditions and it's known as main factor in the landslide transmissivity, and other effective items are: the slope between 5% to 30%, the drainage more than 1250 mm, the height between 500 to 2000 m and the distance from drainage basin between 0 to 4 km. Most of the extremely hazardous zones are pastures and plains that villagers and immigrant tribes use them and their water for grazing live stocks and especially for water cultivation in the slope zones. Eventually we came to this conclusion that AHP method is more accurate and better than other methods because it contains more variables and principled classifications without any expert's direct ideas.