Review of the multiple hydrological functions of watershed ecosystems and their impacts on agricultural water security

Watershed ecosystems are complex ecosystems where human and natural systems are highly intertwined; playing critical roles in agricultural water security through their multi-hydrological functions. This study firstly dissected the concepts of multi-hydrological functions within watershed ecosystems and agricultural water security. Multi-hydrological functions include water source conservation, freshwater supply, runoff regulation, and water quality purification, whereas agricultural water security refers to the controllability of water quantity, quality, supply reliability, and water-related disaster losses in agricultural production. Subsequently, the impact of each hydrological function on agricultural water supply safety, water quality safety, and water disaster prevention was explored. Ecosystems such as forests, grasslands, and wetlands play significant roles in water source conservation, freshwater supply, runoff regulation, and water quality purification, which can increase the amount of water available for agriculture, thus reducing the risks of floods, droughts, soil erosion, and mitigate agricultural pollution, thereby enhancing the level of water security for agriculture within the watershed. There is a trade-off and synergy between the multi-hydrological functions of watershed ecosystems and safeguarding agricultural water security. Engaging in ecosystem protection, restoration, and enhancement of multi-hydrological functions is crucial to ensure the safety of agricultural water use. Considering the existing research gaps, further research was proposed in the areas of mechanistic studies, model development, and practical applications. This includes exploring the interrelationship and coupling mechanisms between hydrological multifunctionality and agricultural water security; developing coupled hydrological models; and conducting ecosystem protection, restoration practices, and landscape optimization to improve ecosystem hydrological multifunctionality. The aim of this study was to provide scientific support for safeguarding agricultural water security and sustainable development from the perspective of ecological barrier functions.