多分汊河道枢纽工程群适应性生态调控研究OA

In this study,the multi-branch channel system in the tailwater area of Ganjiang River was se-lected for study.We investigated the regulation of flow discharge and the diversion ratios among four branches under dynamic inflow conditions and established ecological regulation targets for the tailwater area on a stratified basis.We aimed to provide support for the coordinated development and protection of aquatic ecosystems with the operation of a hub project.The study was based on long-term flow data from the Waizhou hydrological station(1974－2020)and operational data from the hydraulic engineering com-plexes in the Ganjiang River system,and August to March of the following year was selected as the sce-nario design period.An empirical frequency analysis,was conducted on the monthly discharge data from the Waizhou station and discharge values corresponding to 20%,50%and 90%of guaranteed levels were selected for each of the 8 months to represent low-flow,normal-flow and high-flow conditions,resulting in 24 discharge scenarios.On this basis,according to the ecological demands of the braided river channel in different periods and at different levels,a multi-objective system was quantified to minimize the devia-tion from the natural flow diversion ratio,maximize the degree of water environment compliance,and minimize the risk of algal blooms.By considering the comprehensive economic and social benefits of the hub project,such as water supply and navigation,a multi-objective ecological regulation model adapted to the spatiotemporal differentiated ecological demands of the multi-braided river channel was constructed.A third-generation non-dominated sorting genetic algorithm(NSGA-Ⅲ)was used to solve the model and the Nash bargaining method was combined for multi-objective decision-making to identify the optimal equilibrium solutions for ecological scheduling under each scenario.Regulation of ecological diversion across the four branches of the Ganjiang River tailwater exhibited significant monthly variations and different inflow conditions,and a single fixed diversion ratio was insufficient to meet the multiple ecologi-cal demands during the regulation period.There was a trade-off between the objective of maintaining the natural diversion ratio and the objectives of water quality improvement and algal bloom control,while water quality improvement and algal bloom control were compatible.The equilibrium solutions optimized with the Nash bargaining method effectively coordinated the different ecological objectives,suggesting to increase the diversion ratio for the Central and Southern branches from August to October and to prior-itize the coordination between maintaining the natural diversion ratio and ensuring water quality in the Southern branch from November to March of the following year.When upstream inflow is substantial,the ecological and water environmental needs of each branch are more easily met,and the optimized plan re-duces the need for additional water allocation to the Middle and South Branches,and the water diversion pattern across the four branches gradually returns to its natural state.However,under low-flow conditions,even if the diversion ratio for the South Branch is increased,the pressure to improve water quality in the South Branch remained due to the limited total inflow.