Evaluation of the coupled coordination of the water–energy–food–ecology system based on the Sustainable Development Goals in the Upper Han River of China 

Water, energy, food, and ecology are crucial to the sustainable development of society, and their security determines the achievement of the Sustainable Development Goals. Based on Goals 2, 6, 7, and 15 of the United Nations’ Sustainable Development Goals (SDGs), this study analyzed the interactions among the water system, food system, energy system, and ecosystem in the Upper Han River in China, and the current level of achievement of the SDGs in the Upper Han River was evaluated. A comprehensive evaluation index system for this water–energy–food–ecology system was established, and the entropy method and CRITIC weighting method were combined to assign weights to its indicators. The level of coupling coordination in the system from 2000 to 2021 was quantitatively evaluated by using a coupling coordination degree model. A differential autoregressive moving average model was established to predict the process of change in each index over the next 20 years, and an analysis of the degree of coupling coordination was carried out. The comprehensive evaluation development index increased by 113% over last 22 years, and the degree of coupling coordination increased from 0.396 to 0.845, demonstrating that there was stable development in general. The fragile support capacity of the water system for the energy system, food system, and ecosystem had a great impact on the overall comprehensive evaluation index. There were more prominent internal conflicts in SDG 2 for food systems, SDG 6 for water systems, SDG 7 for energy systems, and SDG 15 for ecosystems. These bi-directional dynamics tended to converge in the sufficiency development model in both the historical period and the projected period. The coupling analysis showed that the coupling among SDG 2, SDG 6, and SDG 7 remained at a high level, indicating that there were intrinsic linkages and interactions among the three goals. In the process of promoting the achievement of these goals, the coupling degree also tends to be coordinated in 2022–2041. The results provide a reference for the management and sustainable development of the river basin.