Abstract: The identification of crucial areas of ecosystem service is of great significance for accurate implementation of sustainable development measures and the improvement of regional ecosystem service. Taking Shiyang River Basin as a research unit, we analyzed the spatio-temporal variations of the provision and consumption of water supply services in 2005, 2010, 2015, and 2020. The water supply service flow model was used to quantitatively simulate water supply service flow. The ZONATION model was selected to identify the crucial areas in the Shiyang River Basin in 2020. The results showed that the provision of water supply services in the Shiyang River Basin showed a spatial pattern being high in the south and low in the north from 2005 to 2020, which declined gradually with time. The consumption showed a spatial pattern dominated by cultivated land and industrial land and temporal change with a downward trend in fluctuation. Each year, about 10.8% of water demand gap could be made up by replenishing upstream water resource. In 2020, the crucial areas of water supply service in Shiyang River Basin were 14455 km². We proposed management strategies to repair and improve the capacity of water conservation, flow promotion, and water conservation in crucial areas from the perspective of provision, transmission, and consumption.

Key words: water supply service flow, crucial area, ZONATION model, water resources management, Shiyang River Basin