Impacts of water diversion tunnel construction on vegetation coverage: A case study of large-scale water diversion project in Southwest China

Water diversion projects in Central Yunnan adopt tunnel structures. Tunnel construction alters local groundwater levels, thereby affecting surface vegetation growth. However, the spatiotemporal impacts of tunnel construction on along-route vegetation remain poorly understood. In this study, six monitoring points were selected along the route of the water diversion projects in central Yunnan based on fractional vegetation cover (FVC) and meteorological data, combined with buffer analysis, ordinary least squares (OLS) univariate linear regression, and partial correlation analysis, and the spatiotemporal effects of tunnel construction on FVC were evaluated. The results show that regional vegetation still maintained good growth after tunnel construction, climate may have masked negative impacts, while construction impacts presented obvious spatiotemporal differentiation. In the dry season, tunnel construction adversely affected vegetation in low-elevation areas, with the impact gradually strengthening away from monitoring centers. In the rainy season, construction exerted limited influence, and vegetation growth was mainly controlled by climate change. This study clarifies the independent mechanism of tunnel construction affecting regional vegetation coverage and provides a scientific reference for coordinating engineering construction and ecological protection.