Integrating ecosystem services supply and demand for extreme precipitation events: optimising gully watershed strategies

Extreme precipitation events pose grave threats to human security and sustainable development in gully watersheds. Ecosystem services such as flood mitigation and soil conservation are effective ways to alleviate disasters triggered by severe precipitation. However, current research on the linkage between ecosystem services and damage to Sustainable Development Goals (SDGs) progress during extreme precipitation events remains limited. This study evaluates the discrepancy between the supply and demand of flood mitigation and soil conservation. This information was integrated with expert knowledge to assess SDG progress damage in gully watersheds. We validated SDG progress damage assessment using field investigations and observational data, analysed spatial clustering of damage scores, and simulated damage changes under different soil and water conservation measures. Results showed that: (1) Soil conservation and flood mitigation supply was significantly lower than demand, with minimum supply–demand ratios of −1.11 (Wayao Gully and Xiaolongmen Gully) and −1.28 (Zhaitang Reservoir), respectively. (2) SDG progress damage exhibited spatial heterogeneity, with the most severely damaged zone having an SDG damage score below −0.92 across all goals, comprising 34% of the total gully watersheds. (3) Higher SDG progress damage correlated with weaker soil and water conservation measures in mitigating this damage. Soil and water conservation measures of slopes greater than 15° and within 210 m of the river bank were identified as optimal for coping with extreme precipitation events. This study proposed a novel approach to assess SDG progress damage based on ecosystem services supply and demand under extreme weather events, providing a valuable reference for climate change adaptation measures in gully watershed.