Multi-Objective Simulation-Optimization Coupling Model of the Water Transfer Level in the East Route of the South-to-North Water Diversion Project

To address the water-use conflicts between the original water-receiving areas of the lower Hongze, Luoma, and Nansihu lakes and the receiving areas of the East Route of the South-to-North Water Diversion (ESNWD) project, a multi-objective simulation-optimization coupling model was developed. To ensure that the operating costs of the system are reduced while safeguarding water in the original receiving area of the lakes, the model had two objectives: minimizing the water shortage in the original receiving areas of the lakes and minimizing the total system cost of the ESNWD project. The water allocation scheme was optimized by adjusting the northward water transfer levels of the lakes. The Nondominated Sorting Genetic Algorithm II was used to solve the model and generate a set of non-inferior solutions for the northward water transfer levels of the lakes. The optimal solution for the northward water transfer level in the ESNWD project was obtained using the entropy weight technique for order preference by similarity to an ideal solution method. The results showed that, compared with the current northward water transfer levels, the optimally obtained northward water transfer level solution could reduce the water shortage in the original receiving area by 7.86% at a cost increase of 0.45%, which balanced the water demand of the original lake receiving area with the economic requirements of the water-receiving area of the ESNWD system, respectively. Thus, the proposed solution effectively improves the system benefits.