Quantifying Watershed Protection Potential and Determining Impact Mechanisms in the Shiyang River System Using Hybrid Land Use-Hydrology Modeling

[Objective] The spatial distribution of overall water conservation capacity follows a general pattern of ‘higher in the west, lower in the east’ and ‘higher in the south, lower in the north’. [Method] The InVEST and FLUS models were coupled to calculate Capacity for water source preservation in the Shiyang River Basin in 2020 and predict water retention capacity under three land use alteration scenarios in 2035: ecological protection, natural development, and cropland protection. Correlation analysis techniques were employed to determine the key factors driving the spatial variability of water source conservation potential. [Results] (1) In 2020, the water source preservation ability of the Shiyang River Basin was 4.32 ×10^8 m³. Under the ecological protection scenario, The water source retention capacity increased to 5.25×10^8 m³, under the cropland protection scenario it was 5.33×10^8 m³, and under the natural development scenario, it was 5.28×10^8 m³. The average water source conservation capacity under the three scenarios increased by 22.38% compared to 2020. Overall, The water resource conservation capacity exhibited a general spatial distribution of ‘greater in the west, lesser in the east,’ and ‘stronger in the south, weaker in the north..” (2) The water source conservation capacity was highest in Sunan County (58.31 mm) and Tianzhu County (54.33 mm), indicating their critical importance in water source conservation. Minqin County, with the lowest water source conservation capacity (0.51 mm), had a generally moderate importance for water source conservation. (3) NDVI (r = 8.819, P < 0.05) was a key factor that had a significant impact on water resource sustainability capacity. [Conclusion] It is anticipated that the water retention capacity of the Shiyang River Basin will rise under future scenarios. Water source conservation capacity is positively correlated with NDVI, precipitation, and forest land proportion, and negatively correlated with population density and average temperature. This research provides a visual tool for evaluating the efficient use and conservation of water resources and for enhancing water source preservation functions