Robust Urban Drainage System: Development of a Novel Multiscenario-Based Design Approach

A traditional single-scenario design approach considers the most probable future scenario, which is very risky and may result in high supplementary cost or overpayment (i.e., regret cost). An alternative involves simultaneously considering multiple scenarios. This study proposes a novel two-phase multiscenario-based design approach to optimize the layout and hydraulic design (determining pipe sizes and manhole depths) of an urban sewer system. In the first phase, multiple individual scenarios are adopted to independently identify the optimal layout for each scenario and the requisite hydraulic design. The aim of the second phase is to determine robust solutions for the sewer layout and hydraulic design to minimize construction cost with a constraint on acceptable regret costs over multiple scenarios. The proposed two-phase optimization method was demonstrated with a hypothetical example of an urban drainage system. The results indicate that the proposed multiscenario optimization approach produces a robust sewer network solution that performs well and is cost-effective for different scenarios.