Comparative prioritization of sub-watersheds based on Flood Generation potential using physical, hydrological and co-managerial approaches

One of the important tools for watershed management and optimal decision making is the prioritization of sub-watersheds which can be effective in soil and water conservation and flood management. Hence, the purpose of this study is to investigate different methods of prioritization of sub-watersheds based on flood generation potential using physical, hydrological and co-managerial approaches in the Cheshmeh-Kileh Watershed, Mazandaran province, Iran. To do this, three approaches including physical criteria (i.e., application of game theory based algorithms), hydrological modeling (i.e., using HEC-HMS model) and co-managerial approach (i.e., employing the opinions of local residents, technical experts and policy makers) were used to prioritize sub-watersheds. Finally, the sub-watersheds were classified into three categories based on flood generation potential. The results showed that there is a difference between the results of co-managerial approach with physical and hydrological modeling approaches. According to the research findings, in physical and hydrological modeling approaches, prioritization of sub-watersheds depends on physical factors such as greater slope, area and less time of concentration. But in Integrated Watershed Management (IWM), in addition to the physical and technical aspects, economic, social, political and legal issues must be considered in decision making, which indicates the necessity of the application of co-managerial approach. Based on field observations, sub-watersheds that have been given first priority by co-managerial approach have a significant annual contribution in flood generation due to low vegetation density. In general, it can be said that physical and hydrological approaches consider only physical and geo-environmental parameters and cannot prioritize important issues such as economic, social and political factors that require the views of local stakeholders.