Flood control operation of cascade reservoirs based on complex spillway gate-opening configurations

Conventional flood-control operation of cascade reservoirs typically treats discharge as the decision variable and then derives spillway gate operation decisions, which can lead to spatiotemporal accumulation of scheduling bias and produce operation plans that are difficult to implement. This study proposes a flood-control optimization approach that treats gate opening as the primary decision variable. To overcome the challenges of complex gate-operation constraints, highly nonlinear discharge relationships, and the heavy computational burden of discrete optimization, we analyze the rules governing spillway gate opening configurations, develop a cascade-reservoir flood-control operation model that explicitly accounts for complex opening combinations, and propose an optimization method for gate-opening configurations based on dynamic simulation and progressive searching. Using the Maotiao river cascade as a case study, the maximum water levels at the two control reservoirs are reduced by 0.57 m and 0.92 m, respectively, while water-level fluctuations at three daily-regulated reservoirs decrease by 11.67%, 19.15%, and 16.85%, thereby enhancing operational safety. In addition, the number of spillway-gate actuations drops from 74 to 54 (−29.9%), and the frequency of gate-opening adjustments is markedly reduced, achieving precise water-level control while improving the rationality and implementability of gate operations.