Analysis of Water Conservation Mechanisms in the River Source Area of Northwest Sichuan from the Perspective of Vegetation Cover Zoning

This paper utilizes a localized Integrated Valuation of Ecosystem Services and Tradeoffs (InVEST) model to calculate the spatio-temporal distribution of water conservation in the river source area of northwestern Sichuan over the past 15 years. It explores the influence of climatic and topographic factors on water conservation under different vegetation cover systems (forest, alpine grassland, and plateau marsh) through trend analysis and correlation analysis. The study reveals an upward trend in total water conservation over the 15-year period, following a low–middle–high–low spatial pattern from east to west. Analyzing the correlation between precipitation, evapotranspiration (ET), elevation, and slope with water conservation under three vegetation cover systems, the study found ET negatively correlated with water conservation depth, with correlation coefficients (Rs) of −0.69, −0.71, and −0.70, respectively. Precipitation and elevation are positively correlated with water conservation depth, with R values of 0.21, 0.24, and 0.14 and 0.23, 0.05, and 0.21, respectively. Slope is negatively correlated in forests (R = −0.19), but positively correlated in alpine grassland and swamp systems (R = 0.02 and 0.29, respectively). These findings highlight the significant influence of climate, topography, and subsurface factors on water conservation, offering valuable insights for precise water resource management and ecological protection in the study area.