How Do Human Activities Impact Soil Erosion? A Long‐Term (1985–2020) Study in the Three Gorges Reservoir Area

Construction of the Three Gorges Dam (TGD), the world's largest hydropower project, has triggered profound ecological changes in the Three Gorges Reservoir (TGR) area. Although most previous studies have examined land use/cover (LUC) changes or soil erosion separately, a critical research gap remains in systematically investigating the spatiotemporal characteristics of long‐term LUC changes, soil erosion dynamics, and water quality responses associated with dam construction. This study addresses this gap by integrating multi‐source data from 1985 to 2020. We employed the Revised Universal Soil Loss Equation (RUSLE) to quantify soil erosion dynamics and applied a geographic detector to identify key driving factors and their interactions. Our results indicate that continuous improvements in vegetation significantly mitigated soil erosion from 1985 to 2020, although variations in LUC and soil erosion exhibited pronounced periodic characteristics. During the preparation stage, rural migration and LUC adjustments degraded vegetation in 83.42% of the study area, leading to increased soil erosion; however, subsequent afforestation improved vegetation. However, the interaction between LUC and terrain slope makes sloping farmlands the primary source of soil erosion, accounting for 48.86%–72.19% of the total, which poses a potential threat to water quality in the TGR, particularly in its tributaries. Post‐impoundment, water quality in the reservoir area significantly improved ( p < 0.01). Factor analysis revealed that the relationship between soil erosion and changes in water quality was not statistically significant, whereas terrain slope was the most important contributor to water quality. It is hoped that these insights will provide a reference for developing eco‐environmental protection strategies in similar areas with intensive human activity.