Analysis of the spatio-temporal characteristics of the water retention function of the Wulie River Basin in Chengde City

The Wulie River Basin in Chengde City is an important part of the Jing-Jin-Ji water conservation functional area, and research on its water conservation function is of great significance. Based on the InVEST model, this study analyzes the temporal and spatial characteristics of water conservation from 1990 to 2018. The main conclusions are as follows: 1) The simulation results in the study area were best when the InVEST model Zhang value was 3.7. The average annual water conservation depth and total water conservation of the Wulie River Basin were 83.85 mm and 2.18 × 10⁸ m³, respectively, and showed a slightly downward trend from 1990 to 2018. 2) The water conservation depth of the Wulie River Basin had a significant positive correlation with rainfall (P < 0.05), a significant negative correlation with potential evapotranspiration (P < 0.05), and a negative (though non-significant) correlation with temperature (P > 0.05). 3) The effect of unit area change by land use type on water conservation was, from greatest to least: forest land, grassland, farmland, and construction land. 4) Climate was the leading factor for changes in water conservation in the Wulie River Basin, and the damaging effect of land use change on water conservation is gradually increasing.