Modified InVEST model for spatiotemporal variations of water conservation and its driving factors in the southwestern alpine Canyon region of China from 1990 to 2020

Accurately quantifying water conservation and its drivers is essential for maintaining ecosystem stability and protecting water resources. Vegetation plays a pivotal role by modulating water retention, infiltration, and evapotranspiration. However, previous assessments using the InVEST model have overlooked vegetation dynamics. To address this gap, this study employed a modified InVEST model incorporating vegetation changes to assess the spatiotemporal variation in water conservation and influencing factors in the Southwestern Alpine Canyon Region (SACR) of China from 1990 to 2020. Owing to the unique topographic heterogeneity of the SACR, particular attention was given to the elevation dependence of water conservation. Results indicated that: (1) Precipitation declined, while temperature, evapotranspiration, and vegetation cover increased over the past three decades. (2) Water conservation shifted from a non-significant decline in the original model (−1.37 mm/a, p = 0.071) to a non-significant increase in the modified model (1.06 mm/a, p = 0.067). After 2000, the original model indicated continued decline, while the modified model showed a slight upward trend. (3) Spatially, the original model detected significant decreases across 36.91 % of the region, mainly in central and southwestern SACR. In contrast, the modified model showed positive trends in 64.87 %, with 30.33 % exhibiting statistically significant increases, primarily in the east. (4) Annual precipitation (q = 0.80), elevation (q = 0.58), and vegetation cover (q = 0.53) were the dominant drivers affecting the spatial patterns of water conservation capacity. This study enhances the InVEST model by incorporating vegetation dynamics, offering scientific insights for ecological restoration and water resource management in high-altitude regions.