Spatially-explicit quantitative relationship for a potential PES mechanism: Cascade hydropower development in Yarlung Zangbo River Basin, China

Payment for ecosystem services (PES) is of great importance for the sustainable development of mountain areas, key hotspot regions for the provisioning of ecosystem services. At present, PES researches mainly focus on forest protection, carbon sink trading, and water protection. As an important industry in mountainous areas, cascade hydropower development has generated substantial economic benefits accompanied by social and ecological impacts. However, efficient PES mechanisms to deal with hydropower generation in mountain areas are still unavailable. Therefore, the lacking of PES in mountain systems limits the development of those areas, and compromise the sustainability of hydropower development. The critical reason lies in the lack of a scientific method that can quantitatively analyze the relationship of hydropower stations with a geographical scope at county level (i.e., quantifying the water yield service provided by each county within the cascade hydropower development basin), and with different hydropower enterprises. We use the Yarlung Zangbo River Basin of China as case study area, one of the major hydropower development basins in China. First, we used Integrated Valuation of Ecosystem Services and Tradeoffs (InVEST) model to map water yield service. Then, we calculated the value of water yield service by relating the water yield to the gross output value of hydropower stations. We revealed the relationship (e.g., hydropower stations and identified counties) between the payers and the payees of ecosystem services through mapping and quantifying the provisioning regions in the supply of water yield service and the users (hydropower enterprises). Finally, we discussed the current situation of benefit distribution in cascade hydropower development basin based on the supply and use of the water yield service. The results showed that 1) the spatial distribution of the value of water yield service is uneven: the upper reaches are high-value areas; the eastern region is higher than the western region; and the maximum value (USD 119.2 $/km(2)) is 34 times higher than the minimum value (USD 3.5 $/km(2)). 2) We found that four state-owned enterprises are the direct beneficiaries of water yield service, and 37 counties are suppliers, among which Gongbogyamda, Lhari and Damxung are the first level of supply. 3) Each hydropower station is provided with water yield service by several counties, and the value of water yield service varies greatly in each county, showing spatial differences. 4) Most counties are only partially involved in the process of water yield service being used by hydropower stations (i.e., the boundary of water yield service is inconsistent with the administrative boundary). 5) Huaneng Tibet Yarlung Zangbo River Hydropower Development and Investment Co., Ltd. gets the greatest value (USD 1.8 million $) from the use of water yield service, while China Energy Tibet Electric Power Co., Ltd. gets the smallest (USD 389.1 thousand $). 6) Counties near the lower reaches have gained more economic benefits, while the water yield service they provide have the lowest contribution to hydropower production. Our approach linked water yield ecosystem service and hydropower development effectively, and revealed their complex eco-economic relationship between producers and beneficiaries of ecosystem services, which provides key insights for the designing of a potential PES mechanism.

Automated summary

Payment for ecosystem services (PES) is crucial for the sustainable development of mountain areas. This study focuses on the lack of efficient PES mechanisms for hydropower generation in mountain areas. By using the InVEST model, the researchers mapped the water yield service and calculated its value. The study revealed the relationship between the payers and the payees of ecosystem services and identified spatial variations in the value of water yield service. The findings provide valuable insights for designing a potential PES mechanism in hydropower development.