Development of a decision framework for river health and water yield ecosystem service in watershed

Maintaining river health in a changing environment is an important way to improve the service value of the river basin ecosystem. An ecological flow threshold process with multiple ecological constraints was proposed using the Range of Variability Approach method and the Improved Intra-annual Spreading method. When combined with the multi-source dataset and the InVEST model, a 'ecology-function pattern-driven and decision' service framework was proposed. The study found that the important ecological constraints of the ecological flow in the Xiangjiang River basin changed after the hydrological change (1991-2019). High pulse occurrence times were delayed by 3 d, while low pulse occurrence times and durations were advanced by 8 d and delayed by 10 d, respectively. Temperature, precipitation, and evapotranspiration are all important factors influencing the dynamic characteristics of the basin's water yield services. Human activities and climate change have contributed nearly 19% more to the temporal and spatial differentiation characteristics of water yield in the basin than in the natural period. Additionally, it was discovered that excessive rainfall can inhibit the impact of other variables on water yield within the basin. Furthermore, the pivotal levels of significant meteorological factors that affect the water yield value of the basin were elucidated. This research leads to a better knowledge of watershed hydrological health in changing environments and a scientific basis for local water resource management decisions and optimal utilization of ecosystem service values.