Multi-objective optimization scheduling and inter-objective correlation analysis of large-scale inter-basin water transfer projects under a bidirectional lake operation model

Study region The Jiangsu section of the Eastern Route of the South-to-North Water Diversion Project (JS-SNWDP) in China is a large-scale inter-basin water transfer project that plays a critical role in regional water resource regulation. Study focus This study develops an integrated multi-objective scheduling framework for the JS-SNWDP. First, a bidirectional operation strategy between Hongze Lake and Luoma Lake is proposed based on the system topology and hydrological characteristics, enabling more flexible lake regulation. Second, this strategy is embedded into a simulation-based multi-objective optimization model that jointly considers water-supply performance and lake ecological requirements under relevant operational constraints. Finally, the feedback relationships among key operational objectives are quantitatively examined, and a multi-attribute decision method is applied to identify preferred scheduling schemes by balancing trade-offs among competing objectives, thereby supporting the balanced and sustainable operation of the JS-SNWDP. New hydrological insights for the region Developing an efficient multi-objective scheduling strategy for large-scale IBWTPs such as the JS-SNWDP is essential for improving operational performance under variable hydrological conditions. The proposed bidirectional lake operation strategy provides the following insights: (1) Under representative wet, normal, and dry conditions, the bidirectional operation mechanism (Scenario S2) outperforms the unidirectional scheme (Scenario S1), reducing energy consumption by 13.7%, 11.5%, and 13.2%, total water deficit by 9.9%, 4.1%, and 3.5%, and lake spillage during flood periods by 1.8%, 4.7%, and 6.9%, respectively. (2) The structural equation modeling results reveal that the interactions among water supply, lake ecology, and flood control vary across hydrological conditions: flood-control and water-supply benefits remain positively related but weaken from wet to dry years, while the relationship between lake ecological benefits and flood control shifts from negative in wet years to positive in normal and dry years, with an opposite tendency observed between lake ecology and water supply. Overall, this study provides a practical methodological framework for optimizing water resource utilization and quantitatively interpreting multi-objective interactions in IBWTPs, offering insights for balancing competing demands under different hydrological scenarios.