Impacts of cascade hydropower dam construction on riparian vegetation in the Yalong River Basin

The Yalong River Basin serves as a critical ecological barrier in the upper reaches of the Yangtze River, with its hydropower development playing a key role in China's "West-to-East Power Transmission" strategy. Utilizing multi-source remote sensing and meteorological data from 2000 to 2022, this study integrates partial correlation analysis, structural equation modeling (SEM), and generalized linear models (GLM) to quantify the impacts of cascade hydropower dam (CHD) construction on riparian vegetation (RV) dynamics and its relationship with key climatic factors, including precipitation, soil moisture (SM), temperature, and vapor pressure deficit (VPD). The results indicate a significant increasing trend in riparian vegetation following hydropower dam construction, with the average NDVI increasing from 0.0016 to 0.0023 year⁻¹. The microclimatic effects induced by dam operation have led to increased precipitation, elevated SM around upstream reservoirs, and a decline in both temperature and VPD, thereby enhancing vegetation growth conditions. The construction of CHD has further modified the response patterns of RV to climatic factors, exhibiting predominantly positive trends. SEM analysis reveals that hydropower development is the primary driver of vegetation changes, while climatic factors, particularly precipitation and temperature, exert significant indirect influences. This study underscores the necessity of grasping the multifaceted ecological impacts of cascade hydropower development and strengthening long-term ecological monitoring to support the sustainable management of riparian ecosystems within the basin. Long-term ecological monitoring and adaptive management are critical to mitigate potential negative impacts on riparian vegetation and support the sustainable health of the Yalong River Basin's ecosystems.