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 m${}^2$, 914.15 to 1364.00 GJ, and 184 to 256, respectively. The equal-weight compromise schedule yielded 42.65 m${}^2$, 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.