Evaluation of the Utilization Efficiency of Water Resources in China Based on ZSG-DEA: A Perspective of Water–Energy–Food Nexus

The main resources needed for human survival are water, energy and food, and the research on the relationship among the three resources has become the research topic. Due to the shortage of natural resources, research on the efficiency of water–energy–food (WEF) nexus has become a hot issue among scholars and governments all over the world. The simple models cannot study the correlation among them; the methods of WEF nexus gradually shift from single to integrated model. The data envelopment analysis (DEA) model is the most simple and effective model, which can measure the efficiency value of each decision-making unit (DMU) and overcomes the shortcoming that the evaluation index system needs to give the weight. The DEA can calculate the efficiency value, but it cannot improve the efficiency value of DMU by changing the input. In this paper, the zero-sum gain (ZSG) DEA model is constructed based on zero-sum game theory. The initial efficiency values of 30 provinces in China are calculated, and each DMU is proportionally allocated according to the proportional subtractive method. After several iterations, the efficiency values of all DMUs reach 1, indicating that global optimization has been achieved. Under the condition of effectiveness, the initial input water resources are reconfigured. Finally, some conclusions are made, and optimization strategies are proposed for 30 provinces in China with low water resource utilization efficiency.