Supply and Demand Patterns Investigations of Water Supply Services Based on Ecosystem Service Flows in a Mountainous Area: Taihang Mountains Case Study

The study of water service supply, demand, and flow in the Taihang Mountains in China can elucidate its supply and demand patterns, which are important for the sustainable utilization of water resources. We chose Gangnan Reservoir Basin in the Taihang Mountains as the research area. First, we evaluated the supply and demand of water supply services using the InVEST model and statistical methods. Then, ecosystem service flows were calculated based on river networks and altitude. Finally, the supply and demand pattern of water supply services based on ecosystem service flows was analyzed. The results showed the following. (1) The total supply and demand of water supply services in Gangnan Reservoir Basin were 8.18 x 108 m3 and 3.52 x 108 m3, respectively. (2) At the sub-basin scale, the minimum flow of both static and dynamic water supply services was the same, and the mean was significantly different. The maximum flow was also significantly different. Static water supply service flows were not significantly correlated with altitude, whereas dynamic water supply service flows were significantly correlated with altitude. (3) The demand area in the supply and demand pattern of water supply services based on dynamic ecosystem service flows was notably less than that based on static ecosystem service flows. The supply and demand patterns of water supply services defined the actual water shortage area, the area that pays for ecosystem services, and the areas of ecosystem service ecological compensation, providing a scientific basis for the safe and rational utilization of water resources in mountainous areas.