Evaluation of the symbiosis level of the water-energy-food complex system based on the improved cloud model: a case study in Heilongjiang Province

As the conflict between the supply and demand of resources intensifies, it is critical to deeply study the important relationships and symbiotic evolution mechanisms among water resource development and utilization, energy production, agriculture, and the socioeconomic system to promote multiresource synergy management. This study introduced symbiosis theory to build a regional water-energy-food complex system in which the water-energy-food nexus was the main body and the social-economic-natural system was the external environment. Then, a symbiosis evaluation index system was established from three dimensions, including the symbiotic unit, symbiotic relationship, and symbiotic environment. Using the improved cloud model, we judged the symbiosis level of the water-energy-food complex system in Heilongjiang Province from 2010 to 2019. The results indicated that (1) the symbiosis level of the provincial water-energy-food complex system, symbiotic unit, and symbiotic environment was on the rise from level II in 2010 to level IV in 2019, and the symbiosis level of the symbiotic unit fluctuated between level III and level IV. The system exhibited an overall strong symbiosis state. (2) The weights of the three criteria were ranked as symbiotic environment > symbiotic unit > symbiotic relationship. The state of the social-economic-natural system could be considered a "monitor" of the symbiosis level, the symbiotic unit was an important basis for the evolution of the complex system, and the symbiotic relationship was the shortcoming of the system symbiosis enhancement. (3) The trade-offs between food production and water savings constrained socioeconomic development in the province. The resource demands of the economic and social systems and the emissions to the natural system that occurred during the resource exploitation and utilization processes were important factors affecting the coordinated development of the studied system. Overall, the experimental results were consistent with the research subjects' actual situations, and the government should promote the regional three-way flow of social, natural, and economic resources to allow the targeted management of multiresource security.