Multi-Objective Optimal Design of Detention Tanks in the Urban Stormwater Drainage System: Framework Development and Case Study

Detention tank plays an important role in the flooding control in the downstream areas of the urban stormwater drainage system (USDS) during the wet weather seasons. For complex watersheds with specific local flooding control policies, the conventional optimization and design methods are found to be not sufficient for effectively and optimally locating and sizing appropriate detention tanks any more. This paper investigates the optimal design of detention tanks under the constraints of local flooding control criteria, with the aim to develop an efficient and robust method and framework for the design of detention tank network. Coupled with the SWMM-based hydraulic simulation, a modified particle swarm optimizer is adopted to find out non-dominated solutions to minimize both the engineering cost and flooding risks by taking the local design criteria into consideration for the more realistic local engineering application. To validate the proposed method, a real-life case in SA city in China is taken for example to obtain optimal layout and sizes of the detention tank network under different construction factors and design conditions. Different rainfall return periods are also tested to guarantee the robustness of the optimal solutions. The results of this study confirm the feasibility and validity of the proposed methodological framework for multi-objective optimal design of detention tanks in the USDS.