Abstract:

[Objective] Taking the Shiyang River Basin, a typical arid inland river basin, as the study area, this study aims to explore the spatial distribution and matching patterns of agricultural water and soil resources under different scenarios of future land use change, identify the supply-demand imbalance and its causes in the river basin, and provide support for the planning and decision-making of sustainable agricultural development at the river basin scale. [Methods] Using the FLUS model, this study simulated the spatial patterns of land use of the Shiyang River Basin in 2035 under three scenarios: cropland protection, natural development, and ecological conservation. By introducing the agricultural water and soil resource equivalent coefficient, this study established a matching assessment model for future agricultural water and soil resources in the Shiyang River Basin. Combined with the water yield module of the InVEST model, this study predicted spatiotemporal variations in water yield under three scenarios in 2035 and evaluated the spatiotemporal matching relationships of agricultural water and soil resources in the Shiyang River Basin. [Results] (1) All seven county-level administrative regions in the Shiyang River Basin showed varying degrees of severe water shortage, indicating an overall imbalance in agricultural water and soil resources, with water supply unable to meet the demand of cropland-based agricultural production. (2) The spatial pattern of water and soil resource matching in the Shiyang River Basin was generally better in the west than in the east of the basin. The Gini coefficient ranged from 0.2 to 0.3, showing a slightly increasing trend but still indicating a relatively balanced condition. The average water and soil resource matching coefficient was projected to be 797 m³/hm² in 2035 under different scenarios, compared to 640 m³/hm² in 2020, showing an overall improvement. (3) Although water yield increased to some extent within each county-level region under different scenarios in 2035, the imbalance in actual water utilization and distribution continued to deepen over time. The continuous expansion of cropland under the natural development and cropland protection scenarios made it more difficult to balance the supply and demand of agricultural water and soil resources in Gulang County, Minqin County, and Liangzhou District. [Conclusion] For regions with poor balance between precipitation and evaporation, such as Liangzhou District, a typical resource-based water-scarce region, it is recommended to alleviate water shortage through interregional water transfer and the introduction of external water sources. In regions where agricultural development is dominant, it is advisable to accelerate agricultural modernization, reduce water consumption per hectare, and adjust crop structures. For regions with poor matching between water and soil resources, such as Minqin County, where both resource-based and engineering-related water scarcity coexist, it is proposed to address the imbalance through interregional water diversion and transfer, systematically improving the efficiency of water resource development and utilization.

Key words: water and soil resource matching, FLUS model, InVEST model, Gini coefficient, Shiyang River Basin