Abstract:Quantitative assessment and spatial mapping of supply and demand of water provision service are frontier issues of current research. However, the spatial-temporal connections of supply and demand and the space flow of water provision service still need to be further strengthened. In this study, the Yanhe watershed was selected as the study area. Based on GIS technology and SWAT model, the supply-demand balance and spatial flow models of the water provision service were proposed by integrating multi-source data. According to the proposed methods, the spatial matching characteristics and flow laws of the water provision service in Yanhe watershed were explored at the sub-basin scale. Moreover, the spatial scope of the provisioning and benefitting areas of the basin were determined. The results showed that, from 2005 to 2015, the water supply first increased and then decreased, while the water demand increased year by year. The supply-demand balance of the water provision service deteriorated year by year, and the freshwater security index (FSI) was reported to be 0.095 in 2015. Significant mismatch in the spatial distribution was observed in terms of the supply and demand of the water provision service in Yanhe watershed. This was particularly evident in urban area and surrounding areas of Yan'an city, which is located in the middle reaches of Yanhe watershed, where the contradiction between supply and demand of the water resources was prominent. Under the framework of the water provision service flow, the study defined the spatial scope of the four main benefiting areas within the water basin and the service flow provided by the corresponding upstream sub-basins (provisioning areas), which included the urban areas of Ansai county and Yan'an city, Qinghuabian town, and Yanchang county. The framework and results presented in the study not only provide a scientific basis for realizing the rational allocation of water resources and ensuring water security in the Yanhe River basin, but also provide a reference for the management of water resources in other basins.