Assessing crop production sustainability through a water–energy–food–ecology nexus framework: Evidence from the Huang–Huai–Hai Plain, China

In the Huang–Huai–Hai (HHH) Plain, a major agricultural region in North China, the pursuit of food security has increasingly intensified pressure on water resources, energy consumption, and ecological systems, posing substantial sustainability challenges. However, integrated assessment and optimization of crop production sustainability under the water–energy–food–ecology (WEFE) nexus remain limited at fine spatial scales, constraining the development of targeted management strategies. To address this gap, we developed a composite index framework integrating the information substitutability method and entropy weight method (ISM–EWM–CIF) to assess sustainability status, trade-offs, driving factors, and optimization pathways at the county level. Using this framework, we evaluated crop production sustainability across 479 counties from 2000 to 2020. Results showed that the composite sustainability index declined from 0.34 to 0.31, with water, energy, and ecological sustainability generally lower in the northern counties and higher in the southern counties. Synergistic relationships were identified among water, energy, and ecology subsystems, whereas food production exhibited trade-offs with water (−0.46), energy (−0.41), and ecology (−0.46), highlighting the environmental costs of agricultural intensification. The coupling coordination degree declined in 67.18% of counties, with water scarcity identified as the dominant limiting factor. In addition, a higher proportion of grain crops in total sown area was consistently associated with lower composite sustainability, suggesting unintended ecological costs of grain-oriented production policies. Scenario analysis showed that energy-focused (E n ) and water–energy combined (WE n ) measures were the most effective strategies under single- and dual-factor optimization scenarios, accounting for 67.40% and 46.17% of counties, respectively, mainly in the central HHH Plain. By explicitly quantifying cross-sectoral trade-offs and spatial heterogeneity, this study provides a transferable framework for diagnosing WEFE nexus challenges and supporting region-specific strategies for sustainable agricultural intensification.