Simulation of Spatial and Temporal Variations in the Water Yield Function in the Source Area of the Yellow River and an Analysis of Influencing Factors

The Yellow River source area is an important eco-fragile and sensitive zone in the northeast of the Tibetan Plateau, where anthropogenic disturbances, climate change, and environmental problems have negatively affected the amount of water in the basin, which directly impacts the ecological security and high-quality sustainable development of the Yellow River Basin. Therefore, this study takes the Yellow River source area as its research area. Based on eight periods of land use from 1985 to 2020, topographic, soil, and meteorological data are combined, and a locally modified InVEST model and geological detector method are used to simulate watershed water production, evaluate the spatial differentiation characteristics of watershed water production, and analyze its spatial heterogeneity attribution. The results revealed that water production from 1985 to 2020 varied within the interval of 152.08–302.44 billion m3, with alternating decreases and increases and an overall upward trend. In the spatial distribution, the depth of water production is high in the east and low in the west, and the high-water-production area is concentrated in the counties of Maqin and Gande. In the vertical gradient, the water production capacity is strengthened with increasing altitudes. The spatial differentiation of the water production service and degree of influence is jointly determined by multiple factors. In this work, the parameter Z of the InVEST model was locally corrected to increase the applicability of the Z value to the Yellow River Basin to improve the accuracy of the simulation results, and the spatiotemporal differences in water yield from multiple perspectives were analyzed to provide a scientific basis for the ecological protection and high-quality sustainable development of the Yellow River Basin.