This paper is the result of ecological geological survey engineering.

Objective As the core water source area for the Middle Route of the South-to-North Water Diversion Project, exploring the spatiotemporal evolution patterns and driving mechanisms of the water conservation function in the upstream basin of the Danjiangkou Reservoir is of great significance for safeguarding the sustainable operation of the project.

Methods Based on the InVEST model, this study analyzed the spatiotemporal evolution pattern of water conservation in the upper basin of the Danjiangkou Reservoir from 2010 to 2023, and examined its response to land use types and elevation. The optimal parameter geographical detector model was applied to quantify the interactive driving effects of multiple factors including land use, elevation, NDVI, and nighttime light index under different precipitation conditions.

Results The interannual fluctuation of water conservation in the upstream area of the Danjiangkou Reservoir exhibits a strong coupling with precipitation processes and an overall slight increasing trend. Spatially, it presents a distribution pattern of "higher in the south and lower in the north."; Among different land use types, the water conservation capacity follows the order: shrubland > forestland > grassland > cropland > construction land. Along the elevation gradient, the water conservation capacity generally tends to decrease as altitude declines. the results of geographical detector show that precipitation is the main driving factor in dry years, land use type and precipitation jointly dominate in wet years, and land use type is the main driving factor in normal years.

Conclusions The overall water conservation function of the upper basin of the Danjiangkou Reservoir is relatively strong. Basins and hilly areas surrounding the reservoir are low-value areas of water conservation, and precipitation and land use type are the main driving factors.