Multifunctionality evaluation and coupling coordination analysis of the water-energy-food system

Research on the multifunctionality of the water-energy-food system is of great significance for understanding the comprehensive efficiency of resource systems and promoting collaborative governance. Based on China’s provincial panel data from 2002 to 2023, this study constructs an evaluation index system for the multifunctionality of the water-energy-food system, adopts the entropy weight-TOPSIS method and coupling coordination degree model to measure the spatiotemporal differentiation of system multifunctionality, and reveals the evolutionary law of coupling coordination among the four major functions. The results indicate that during the study period, the national average value of the system multifunctionality index rose steadily from 0.387 to 0.486, forming an overall spatial distribution pattern characterized by high and stable index values in the eastern and central regions and locally leading levels across western China. Obvious differences exist in the spatiotemporal patterns of the four major functions. The overall coupling coordination degree among functions presented an evolutionary trend of first declining and then rising. It dropped to around 0.55 in 2003, the lowest value during the study period, and entered a steady growth stage after 2012. Most provincial-level regions achieved synchronous improvements in both multifunctionality levels and coupling coordination degrees, while the pattern of unbalanced regional development remained relatively stable.