Prioritization Flooding of Sub-watershed based on Morphometric Parameters Using GIS Technique

Among natural disasters, flood is the most widespread and large hazard which result in high costs and heavy destruction. Hence prioritization of potential flooding areas has gained importance in natural resources management, especially in the context of watershed management. Therefore the aim of this study is prioritization of flooding in sub-watersheds based on morphometric parameters using GIS technique. For this reason, Pol-Doab Shazand watersheds on the basis of relief ratio, change in drainage density, area of whole watershed and crests was divided into 24 sub-watersheds designated. Then 10 Morphometric parameters namely drainage density, bifurcation ratio, stream frequency, length of overland flow, form factor, shape factor, elongation ratio, circulatory ratio, compactness coefficient and derange texture are obtained for each sub-watershed. In this research various morphometric parameters including linear and shape characteristics have been determined for each sub-watershed and assigned ranks SW1 through SW24 on the basis of value and relationships. Therefore sub-watersheds have been classified into three categories as high, medium and low in terms of priority for soil and water conservation measures. The results show that 14 sub-watersheds (SW5, 7, 8, 10, 11, 12, 14, 15, 16, 17, 19, 20, 22 and 23) out of the 24 qualified for high priority class, 6 sub-watersheds (SW6, 9, 13, 18, 21 and 24) have been categorized as medium priority and 4 sub-watersheds (SW1, 2, 3 and 4) have been categorized as low priority based on the integration of morphometric.