Research on optimal allocation of soil and water resources based on water-energy-food-carbon nexus

Current population growth and rapid urbanization in China have intensified the demand for water, energy, and food. This is threatening the intertwined global water, energy, and food security. Therefore, it is necessary to formulate interconnected and interdependent water, energy, food, and carbon policies. In this study, based on the theory of water-energy-food-carbon nexus, a soil and water resource optimization allocation model was developed by establishing an optimization modeling framework to achieve coordination between various sectors of water allocation. The model is an effective decision-making tool that fully considers the close relationship within the nexus system, and multiple uncertainty conditions. It was applied on the Fen River Basin in Shanxi Province as the study area, and a series of optimized allocation schemes were obtained. The results indicated that the current water allocation to each sector is meeting its minimum water demand. The planting structure optimization of two crops, wheat and corn, reduces the regional agricultural water consumption. For example, in dry years, the area of wheat cultivation (which needs more irrigation and has lower net economic benefits) is reduced and that of corn (which needs less irrigation and consumes less water) is increased in each subdistrict. The wheat plantation area in the midstream and downstream is decreased by 2.08% and 26.25%, respectively. The water use structure of crops indicated that precipitation and groundwater resources significantly contribute to the production of both crops throughout the entire growth process. This model can be applied in other regions; the model's economic and ecological benefits are combined so that decision makers can consider the stability of the water-energy-food-carbon system and provide optimal resource allocation under various scenarios, contributing to achieving the goal of sustainable development.