Study on effect of high-altitude hydropower development on ecological environment quality and its driving forces

Abstract

[Objective] Accurately assessing the ecological and environmental effects of hydropower development in high-altitude, ecologically sensitive regions is essential for maintaining the ecological security barriers of these areas. Therefore, an improved Remote Sensing Ecological Index(IRSEI) model is proposed to study the effect of hydropower construction on regional ecological environment quality in a specific area of the Qinghai-Xizang Plateau. [Methods] Taking a hydropower station in the Qinghai-Xizang Plateau as the study object, and considering the fragile soil and complex topography of high-altitude regions, a normalized difference mountain vegetation index(NDMVI) was established. At the same time, soil erosion modulus was introduced as a soil erosion indicator. An improved remote sensing ecological index(IRSEI) for high-altitude hydropower development areas was proposed. The spatiotemporal dynamics of the IRSEI and its driving factors were analyzed using method such as Theil-Sen slope estimation, Mann-Kendall trend analysis, and Hurst exponent. [Results] By replacing NDVI with NDMVI and incorporating the soil erosion indicator, IRSEI was more suitable for ecological quality monitoring in areas with complex topography. The results showed that hydropower development significantly affected the landscape structure of the basin, particularly grasslands and forests, leading to a reduction in their area. The average IRSEI value decreased from 0.53 before hydropower construction to 0.42 after construction, with the most significant ecological degradation occurring in the second year of construction. During the operational period, the value increased to 0.57. The IRSEI grades of forests and grasslands in the basin were mainly excellent and good, while construction and cultivated land areas were mainly poor and very poor. The future development trend of IRSEI was expected to stabilize, with more than 60% of the basin area remaining unchanged. The main controlling factors for the spatial differentiation of IRSEI in the study area were annual precipitation, average annual temperature, NDVI, and land use changes. [Conclusion] During the construction phase, hydropower development significantly affects the landscape pattern and IRSEI of the study area. During the operation of the hydropower station, the ecological environment of the study area shows an overall positive change, with ecological deterioration mainly concentrated in urban areas. In the future, it is essential to enhance ecological restoration in this basin, taking into account human activities and climate change, and ecological protection and restoration efforts should be carried out. The research findings provide theoretical and data support for implementing targeted ecological protection and promoting high-quality development in the basin.

Keywords

hydroelectric development / Qinghai-Xizang Plateau / Google Earth Engine(GEE) / improved remote sensing ecological index / geodetector / Hurst exponent / influencing factors