Exploring optimal joint operating rules for large-scale inter-basin water transfer projects with multiple water sources, diversion routes, and water demand areas

Study region: The Jiangsu Province section of the South-to-North Water Diversion Project (JSSNWDP) is an essential section of the SNWDP, which includes multiple water sources, diversion routes, and water demand areas. Study focus: Exploring effective operating rules for the JSSNWDP is critical to improving its long-term operational performance. However, deriving the operating rule for the JS-SNWDP remains a pressing challenge due to the complexity of its water allocation, which requires trade-offs between multiple water sources and diversion routes when supplying and transferring water. Here, we design a new form of the joint operating rules for the JS-SNWDP that includes water-supply rules and water-transfer rules, and establish a multiobjective optimization operation model by simulation-optimization approach to identify the optimal joint operating rules that contribute to the improvement of water supply reliability and the reduction of operation cost. New hydrological insights for the region: The proposed joint operating rule shows obvious advantages over the regular operating rule, with an increase in the water supply rate (2.0%) while the strongly reduced pumping water (24.7%). Meanwhile, compared with the regular operating rule, the joint operating rule enables a more rational use of the runoff regulation capacity of the lakes, which obviously reducing the pumping water from the Yangtze River and the surplus water in the two lakes obviously. The findings of this study are applicable to improve the operational performance of the JS-SNWDP, and provide a reference for exploring the joint operating rules for other IBWTPs with similar structures.