Increasing the available water diversion volume of water source project through flood resource utilization: A case study of the middle route of the South-to-North water diversion project in China

Water supply operating rules are critical for guaranteeing the safety of the water supply in the source project and receiving areas and overcoming the uneven distribution of water resources among different regions. Previous studies have mainly focused on optimizing the water supply operating rules to balance multiple benefits under the current engineering design parameters. In this study, a framework is proposed in which the water supply operating rules for the resource reservoir are adapted through flood resource utilization. The correlations among seasonal floods are first analyzed by considering the influence of water diversion projects. The seasonal flood-limited water levels (FLWLs) are then re-designed in terms of a flood damage assessment index under the deduced most-probable seasonal floods. Finally, the water supply operating curves of the resource reservoir are optimized by adopting the recommended seasonal FLWLs. The middle route of the South-to-North Water Diversion Project in China is taken as a case study. The results show that the recommended seasonal FLWLs are 160.2 m in summer and 164.2 m in autumn, and that the annual average available water diversion volume can be increased by 0.52 billion m3 without increasing the flood risk. Compared with the current water supply operating rules, the optimal operating curves make the annual distribution of the available water diversion volume more uniform in different typical-year scenarios and reduce the surplus reservoir water. These findings are helpful for exploring the potential of water resource utilization.