ASSESSMENT OF FLOOD HAZARD ZONATION IN A MOUNTAINOUS AREA BASED ON GIS AND ANALYTICAL HIERARCHY PROCES

In this study, flood hazard areas were evaluated in the Lighvan catchment as a mountainous area. So after preparing seven criteria such as slope, flow accumulation, distance from drainage network, lithology, runoff depth, land use and vegetation cover, the relative importance of criteria and sub-criteria for occurrence of the flood were weighted using the Analytic Hierarchy Process (AHP) method and then flood hazard map was extracted by Flood Hazard Index in GIS. The results of weights showed that flow accumulation, distance from drainage network and slope are the most and vegetation cover and Ethology are the less importance factors in flood risk of the Lighvan catchment. Flood hazard zonation map divided to five classes; very low, low, moderate, high and very high. According to this, 3.35% of the catchment area in the range of very high risk and 5.97% in the range of high risk. Also weak pasture, rainfed farming, barren land, garden and dense pasture have high distribution in high and very high flood hazard classes. Finally regarding to priority for management and mitigation of flood hazard, the sub-catchment 4, 13 and 19 of the study area is facing serious problem of flood hazard, spatially Lighvan village is located in sub-catchment 4 and Beyragh villages is located in sub-catchment 3. So flood hazard mitigation and flood control in these sub-catchments should be implemented immediately. The results of this study act as guidelines for managers and planners to determine rational management of catchment for mitigation of flood hazard.