Evaluation and diagnosis of water resource carrying capacity in the middle reaches of the Heihe River under SEEA-W perspective

Water scarcity poses a significant challenge to sustainable development in arid regions, necessitating the adoption of advanced and interpretable methodologies for assessing water resource carrying capacity (WRCC). This study constructs a dynamic ‘Production-Supply-Use-Consumption-Emission’ (PSUCE) system based on the System of Environmental-Economic Accounting for Water (SEEA-W). It proposes the TOPSIS-XGBoost-SHAP-PDP (TOPSIS-XSP) integrated approach to evaluate WRCC in the middle reaches of the Heihe River (MRHR) from 2003 to 2023. The TOPSIS model reveals a ‘fluctuating increase-peak decline’ trend: carrying capacity reached Level IV (basic capacity) in 2019 before declining due to drought and structural constraints. Key obstacles include agricultural water use efficiency (C10), domestic sewage discharge (C20), and Sewage Reuse Rate (C23). SHAP analysis further elucidated the positive contributions of C10 and C23 alongside the significant negative impact of C22 (total emissions). PDP analysis revealed non-linear relationships and critical thresholds: agricultural water conservation exhibits diminishing marginal returns beyond a specific efficiency level. At the same time, WRCC declines sharply when pollutant emissions exceed 84 million m 3 . These findings demonstrate that the mixed methods approach effectively combines macro-level trend diagnostics with explanatory insights into mechanism drivers, providing a robust foundation for addressing water management challenges through adaptive efficiency improvements, pollution control, and structural water allocation strategies. • Evaluated WRCC in the study area at the basin scale. • A new system of evaluation indicators has been constructed through SEEA-W. • A novel research framework has been constructed: TOPSIS-XGBoost-SHAP-PDP. • Detailed analysis of key issues in conjunction with data from water accounting.