Abstract: Accurate quantification of the value of water conservation function is crucial for assessing the effectiveness of ecological restoration and promoting the realization of ecological product value. Shanxi Province, characteri-zed by fragile ecosystems, has been a key implementation area for national ecological projects. However, precise economic valuation of the ecological restoration outcomes in Shanxi Province remains limited. To address this, we integrated the InVEST model, Monte Carlo model, and a shadow project approach incorporating geomorphic zoning-based differential pricing to analyze the spatiotemporal variations of water conservation capacity and its economic value in Shanxi Province from 2005 to 2023. The driving mechanisms were further investigated using Geodetector and principal component analysis. The results showed that the total water conservation capacity in the province showed an overall increasing trend from 2005 to 2023, with the increase in its economic value (66.8%) being much higher than the increase in water conservation capacity (8.7%). Water conservation capacity exhibited a spatial pattern of higher in the south and lower in the north, whereas the growth rate of water conservation value pre-sented characteristics of higher in the north and lower in the south, rising in the west and slow in the east. The Lyuliang mountainous area in western Shanxi and the northern region showed particularly significant growth, with the strongly eroded loess ridge-hill area recording the highest value increase of 91.9%. The dominant factors and interactive mechanisms driving spatial variations of water conservation value demonstrated clear geomorphic dependence. In transitional geomorphic zones with intensive human activities, the synergistic effect between normalized difference vegetation index, and construction land played a dominant role. In ecologically vulnerable loess zones and the arid areas of northern Shanxi, the climate-vegetation synergy served as the key regulatory mechanism. Artificial ecological projects had generated significant marginal value returns in ecologically fragile zones. Future ecological management should shift towards a “zonal governance, precision enhancement” strategy. The high-value-return areas such as western and northern Shanxi should focus on improving vegetation cover and grassland quality. The high-capacity areas such as southeastern Shanxi should strengthen ecological space protection and structural optimization. At the provincial scale, the ecological space baseline must be strictly maintained to systematically enhance water conservation value.

Key words: water conservation value, InVEST model, shadow project method, geodetector