Abstract: The Yangtze River, known as the mother river of the Chinese nation, plays a crucial role in establishing a trans-provincial ecological compensation mechanism in the Yangtze River Basin. This mechanism holds great significance in harmonizing the interests between the ecological protection areas and the beneficiary regions, thereby fostering high-level ecological conservation and promoting sustainable development within the basin. Focusing on the mainstream of the Yangtze River, we propose a conceptual framework for trans-provincial ecological compensation based on water quality and quantity. We delve into the essential components, compensation standards, fund allocation, monitoring and assessment indicators, as well as the safeguarding system of trans-provincial ecological compensation. Furthermore, we conduct a case study to illustrate the application of trans-provincial ecological compensation in the main stream of the Yangtze River using the 2018 data. The findings reveal that the primary contributing provinces (autonomous regions, municipalities) to the trans-provincial ecological compensation in the main stream of the Yangtze River are Jiangsu, Shanghai, and Anhui, while the provinces (autonomous regions, municipalities) receiving the compensation include Sichuan, Qinghai, Yunnan, Tibet, and Jiangxi. These results demonstrate the compensation relationship between downstream provinces, benefiting from the protective measures taken by upstream provinces in the Yangtze River main stream. We suggest that a comprehensive trans-provincial ecological compensation mechanism should be established at the basin-wide level, involving the simultaneous participation of multiple provinces (autonomous regions, municipalities). Initially, water quality and quantity can be considered as fundamental compensation factors, and over time, the range of compensation factors can be gradually expanded, alongside the enhancement of compensation evaluation standards and the refinement of the ecological compensation safeguarding system.

Key words: horizontal ecological compensation, compensation standard, river basin, water quality and quantity, Mainstream of Yangtze River