The water-food-energy nexus evaluation and optimization of cropping system in the North China Plain: A case of county scale

Water, energy, and food, which are closely related to human beings, have been proposed by the Sustainable Development Goals, and there are closely related but contradictory relationships among the three. As one of China's main grain-producing regions, the North China Plain (NCP) with dominant grain-oriented cropping system is faced with severe challenges for agricultural sustainable development, such as water and energy shortages, as well as grain safeguard. In this study, a "TKL-WEFN" model combining Tapio decoupling, Kaya, and LMDI was used to evaluate the synergistic relationship from the water-energy-food (WEF) and determine the key drivers taking Wuqiao County in the NCP as a case. The results showed as follows: the synergistic relationship between water-food, as well as energy-food, showed a "M" shaped fluctuation trend from 2009 to 2018 in Wuqiao County. The best performance was achieved in 2011 and 2016, with the state of high yield and low resource consumption. Food increased by 9.43% and 3.52%, while water resources decreased by 5.95% and 8.91%, and energy decreased by 5.36% and 2.15% in 2011 and 2016, respectively. The changes in water consumption for irrigation and fossil energy consumption per unit area of maize and cotton, as well as the adjustment of planting structure, are the main factors affecting the sustainability of crop systems from 2009 to 2018. Water-saving irrigation, no-tillage, and cropping system transformation can improve resources supply and demand, saving 4.61%-50.27% (with an average of 19.47%) of water consumption and 1.91%-13.08% (with an average of 6.45%) of energy consumption by scenarios analysis. Therefore, changing grain-oriented cropping system while maintaining food security and developing water-saving irrigation technology can accelerate the realization of green agriculture.