A novel integrated model for quantifying agricultural water resource utilization efficiency under carbon neutrality: Regional assessment, spatiotemporal heterogeneity and influencing factors analysis

Effectively quantifying agricultural water utilization efficiency (AWUE) under carbon neutrality is critical for sustainable resource management. However, existing assessment models often overlook the integrated impacts of agricultural carbon emissions and sequestration on AWUE. To address this gap, this study develops a novel integrated assessment model that incorporates agricultural carbon emissions and sequestration into a comprehensive input-output index system. This model not only quantifies AWUE but also comprehensively analyzes its spatiotemporal patterns and driving factors. Applying this model to the Beijing-Tianjin-Hebei region from 2013 to 2022 reveals several key findings: (1) AWUE demonstrated significant spatial heterogeneity with an overall increase of 82.2% (from 0.56 to 1.02 on average), showing a south-to-north progression. (2) Significant positive spatial agglomeration was identified (Moran’s I: 0.32–0.48), with high-high clusters predominantly located in the southwest. (3) The impact of water-saving irrigation coverage (the q value rose from 0.64 in 2013–0.791 in 2021) and agricultural economic share (from 0.58 to 0.66) increased over time, while the impact of agricultural carbon emissions (from 0.87 to 0.46) decreased significantly. (4) Carbon-incorporated approach effectively optimizes agricultural resource allocation, reducing redundancies in inputs like fertilizer (e.g., by 83.7% in Cangzhou) and enhancing AWUE compared to scenarios without carbon considerations. The proposed model advances conventional assessments not only by integrating carbon emissions and sequestration to fill a critical gap in the literature, but also by providing a scientifically grounded tool for policymakers. This enables the formulation of targeted water-carbon synergy policies to support sustainable agricultural water management.