Intelligent Pump Operation and River Diversion Systems for Urban Storm Management

Large-scale networks of sewer pipes, control gates, and pump stations are the primary facilities of urban drainage systems for mitigating flood risks. During flooding periods, cooperation of pumps and control gates plays a major role in efficiently reducing flood inundation. In this study, a real-time optimization approach is developed to find optimal policies for collaborative operation of drainage facilities, including detention storage and control gates, and multiple pump stations. The online approach is a predictive control scheme based on a harmony search algorithm that provides actively optimal operational policies according to real-time rainfall information. Operational models are applied to a prototype network in a portion of the Seoul urban drainage system, and results are compared with those of traditional operating rules. A high efficiency for the operational model of both the river diversion system and pump stations in terms of flood mitigation is demonstrated. For the river diversion system, considering several rainfall events, active control of the gates provides in average 48% peak discharge reduction in target points against 26% reduction obtained by a passive one. The active control can provide mostly 47% improvement compared with the passive policy just by delaying and controlling the release of storm water into detention storages. In parallel, the optimal online pump station operation decreases the collected storm water peaks by an average of 33 and 21% in two studied pump stations compared with the conventional approach even when a smaller number of pump switches (15% in average) is used, an advantage related to maintenance costs. More specifically, for the six separate rainfall events considered, the optimal policies mostly eliminate the storm water depth violations in pump stations, whereas there is a considerable violation for all events when the traditional operating rules are used. These results show that optimizing pumping operations is a practical and highly effective way to reduce flood volumes and urban inundation without making changes to the existing system infrastructure.