The optimum design of flood control system using multivariate decision making methods (case study: Kan River catchment basin, Iran)

To counter the risks of flooding and reduce its harmful effects, there are different instruments, structural and non-structural methods. These methods’ results depend on different conditions, such as technical, economic, social–political and environmental ones. Among the different structural methods of flood control in a particular river, the simultaneous use of several methods will increase the safety and performance of the plan. So in order to provide an effective flood control design, predicting the hydraulic behavior of river toward potential floods is as important as determining the most economical and efficient method or the methods for flood control. The purpose of this study is to find a combination of detention dams in the upstream catchment area and downstream of coastal residential area; so for that combination, structures’ composition cost will be minimum and the reduction of output peak discharge will be maximum. To determine the best combination, multiple decision making concept and Topsis method are used. The results showed that a combination of detention dams (combination number 43; dams 1, 2 and 8), can be introduced as a superior combination of flood control. For the hydraulic issues, the superior design (combination number 43), will lead to 31% reduction in peak discharge of output rather than non-combination dams. In addition, diffusion well-managed flood control and superior design control the flooding very well.