Optimal Joint Operation of Multiple Gates and Pumping Stations in a Tidal River Network

Coastal plain river networks require coordinated gate-pump operation when typhoon rainfall coincides with tidal backwater. This study implemented a SWMM–NSGA-II simulation–optimization framework for the northern drainage river network of Yuyao City, China, using Typhoon In-Fa as a representative event. The framework links distributed rainfall-runoff simulation, river-network hydrodynamics, tide-affected outfall pumping, and coordinated operation of coastal and internal hydraulic structures. Water-level bounds at Linshan, Dongpu, and Mazhu were imposed as full-process hard constraints, and three objectives were minimized within the feasible domain: water-level penalty, pumping energy consumption, and gate-pump switching count. The final Pareto set contained 36 feasible non-dominated schedules, all with zero constraint violation (CV=0). The discrete quadratic water-level exceedance penalty index at the three control stations, the total energy consumption of the three controlled pumping stations over the 72 h horizon, and the cumulative number of binary state changes of the controlled sluice stations and individual pump units ranged from 39.29 to 51.59 m2, 914.15 to 1364.00 GJ, and 184 to 256, respectively. The equal-weight compromise schedule yielded 42.65 m2, 967.82 GJ, and 215 state changes. Compared with the historical baseline operation without the newly commissioned Taojialu and Leanhu pumping stations, this schedule reduced the 72 h accumulated exceedance above the target levels at the three control stations from 25.43 to 8.11 m·h , corresponding to a reduction of 68.1%. The results indicate distinct hydraulic roles for coastal and internal structures: coastal outfalls mainly control tide-window drainage and forced-discharge capacity, whereas internal gates and pumping stations regulate water redistribution and the transmission of water-level reductions.