Synergistic assessment of water-related ecosystem services: integrating meta-analysis and InVEST in the Huai River Basin, China

Introduction Water-related ecosystem services (WES) underpinned environmental sustainability and water governance, yet their valuation had often remained fragmented and weakly connected to ecological processes. This study aimed to develop an integrated framework for assessing WES in the Huai River Basin (HRB), China. Methods Meta-analysis was combined with the InVEST model to assess WES. Based on 216 global observations, a meta-regression model was developed to estimate the monetary value of WES. The InVEST model was used to simulate the spatiotemporal dynamics of three biophysical functions—water yield, water conservation, and water purification—from 2000 to 2021. A Coupling Coordination Degree Model was then applied to evaluate the synergies and trade-offs between monetary valuation and ecological performance. Results The mean annual monetary value of WES increased by 55.14% over the study period, mainly driven by improvements in water yield and water conservation. In contrast, water purification fluctuated markedly, reflecting increasing nutrient pressures associated with human land use. The coordination between ecological and economic dimensions improved from a non-coordinated state to an excellent level, reaching D = 0.910 in 2020. Discussion The results indicated that ecological improvements in the HRB were increasingly reflected in economic terms. However, the volatility in water purification suggested that aggregated monetary indicators might obscure declines in functions critical to water safety. The integrated meta-analysis—InVEST framework provided a transparent and transferable approach for basin-scale WES assessment and supported ecological restoration investment and basin-scale water-quality management.