Integrated assessment of the sustainable water-energy-food nexus in China: Case studies on multi-regional sustainability and multi-sectoral synergy

Water, energy, and food (WEF) are pivotal resources for the sustainable development of human society. Integrated assessment of the sustainable WEF nexus is essential to enhance resource efficiency and security, but there is a crucial gap to be filled in assessing the coupling relationship among sustainable WEF subsystems and improving multi-sectoral synergy. In this paper, a comprehensive indicator system for sustainable WEF nexus assessment was constructed based on theme-based frameworks and nexus thinking, and the combination weighting method based on game theory (GT-CW), the improved TOPSIS method based on gray relation degree (GRD-ITOPSIS), and the coupling coordination model were proposed for integrated assessment. The sustainability of WEF nexus in 30 regions of China from 2010 to 2019 was assessed and the spatiotemporal differences of the coupling coordination degree of sustainable WEF nexus were analyzed. The results revealed that the sustainability of WEF subsystems evidently affected the overall sustainability of regional WEF nexus. The change range of sustainable WEF nexus in different years was slightly lower than that of a single subsystem. The sustainability of WEF subsystems were highly coupled, and the WEF nexus in each region was within the coordinated development range. However, most eastern regions were at the intermediate coordinated development stage, and some western regions maintained at primary coordinated development stage for a long time. According to the results analysis, specific policy recommendations were proposed. The findings of this study can provide a useful reference for developing countries to improve resource management and promote sustainable development. (1) Sustainable water-energy-food nexus in 30 regions of China was assessed. (2) Combination weighting method was optimized by game theory. (3) TOPSIS method was optimized by gray relation degree. (4) The synergy among WEF nexus were analyzed by coupling coordination degree. (5) The WEF nexus in each region was within the coordinated development range.