Evaluation of the Coupled Coordination of the Water–Energy–Food System Based on Resource Flow: A Case of Hubei, China

External environmental changes, such as climate, industrial expansion, and population growth, threaten the sustainable development of the water–energy–food (WEF) system. Clarifying the intricate nonlinear relationships within this system and revealing the degree of coupling coordination and evolutionary trends within the WEF system can provide feasible pathways for regional sustainable development. Taking Hubei Province as the study area, this research quantified resource flows between dual systems from a resource consumption perspective. It then analyzed the temporal evolution characteristics of resource interactions within the WEF system from 2003 to 2023. In addition, this WEF system was evaluated by an evaluation index system according to the resource utilization level of the single system and the resource flow level of the dual system, and the CRITIC method was employed to assess the coordinated development of the WEF system in Hubei Province from 2003 to 2023. Finally, the coupling coordination degree for 2025 to 2040 was predicted through the grey GM (1,1) model. The results show that the comprehensive development evaluation index exhibited a trend of initial decline followed by an increase from 2003 to 2023. Among these, the water resources system demonstrated the relatively optimal comprehensive development status, while the energy system performed the worst. The WEF system remained in a high-level coupling stage, with its degree of coupling coordination showing a pattern of initial decline followed by an increase, reaching its peak in 2023 and entering a moderately coordinated stage. Within the dual-coupling systems, the water–food (WF) system achieved the highest level of coordinated development, reaching the good coordination stage. The GM (1,1) model indicates that Hubei Province’s WEF system can gradually achieve a good coordinated stage between 2024 and 2040.