Footprint fluxes and network characteristics in the agricultural water-land-energy-carbon nexus system of the North China Plain

The North China Plain (NCP) is the second-largest plain in the grain-producing region of China. However, the resource-environment conflicts are intensified in the water-land-energy-carbon (WLEC) nexus system. It is often required to clarify the linkages among these four elements, particularly for national food security, resource allocation, and carbon neutrality. In this study, an environmentally extended multi-regional input-output (EE-MRIO) model was employed to quantify the direct consumption and embodied flows of agricultural water, land, energy, and carbon in the NCP. Ecological network analysis (ENA) and a coupling coordination degree model were applied to examine the network and interrelationships in the WLEC system. The results revealed that: 1) The direct resource consumption and embodied flows exhibited upward trends with significant spatial heterogeneity from 2012 to 2017. The trade-embodied agricultural water use, cropland utilization, energy consumption, and carbon emissions between the NCP and the rest provinces of China increased by 5.295×10⁹m³ (16.5%),1.918×10⁵hm² (3.1%),1.186×10⁶t (17.2%), and 3.942×10⁶t (20.9%), respectively, indicating the primary grain-producing region. 2) In general, virtual agricultural resources shifted from the underdeveloped to the developed regions, and gradually concentrated in the areas with high population density, large economic scale, and active markets. 3) The WLEC network exhibited low cycling ratios with substantial inter-regional disparities and resource mobility constraints. Inter-provincial ecological relationships were dominated by competition and predation, with limited mutualism. The network demonstrated low efficiency, high redundancy, and loose structure. It is often required for the sustainability of the coupling coordination degree of the WLEC system. Three recommendations were proposed to advance high-quality agriculture with resource scarcity in the NCP. Firstly, the resource linkages can be optimized to consider the synergistic effects among water, land, energy, and carbon. Secondly, the resource flow pathways can also be improved using infrastructure and market-based instruments. Thirdly, the resource constraints and emission reduction can be simultaneously promoted in modern agriculture.