Ecological and environmental impacts of large-scale interbasin water transfer projects: A case study of the middle route of the south-to-north water diversion project

Interbasin water transfer is a critical engineering strategy for addressing the imbalance between water supply and demand. However, its potential ecological impacts are often overlooked. This study takes the Middle Route of the South-to-North Water Diversion Project (SNWD-MR) as a case study, systematically reviews its ecological impact characteristics in different regions and dual effects, summarizes existing protective measures and implementation achievements, and deeply analyzes current issues and future development directions. The results show that the SNWD-MR has promoted ecological restoration in the water source areas while effectively alleviating water scarcity in the receiving areas, but it also brings challenges such as reduced runoff, increased water environmental risks, and changes in regional ecological patterns. Although some protective and restoration measures have shown initial effectiveness, they still face shortcomings such as inadequate monitoring and evaluation systems, unclear multi-factor coupling effects, and urgent need for improvement in ecological compensation mechanisms. Future development should focus on constructing a comprehensive assessment framework that considers long-term cumulative impacts, coordinating engineering benefits with ecological protection, and maximizing its overall value to provide a replicable experience for similar interbasin water transfer projects worldwide.