Supply-demand risk assessment and multi-scenario simulation of regional water-energy-food nexus: A case study of the Beijing-Tianjin-Hebei region

The risks associated with water-energy-food (WEF) nexus can be determined by analyzing the three resources as a system and subsequently measuring the probability of resource shortages in this system under the influences of external factors such as climate, economy, and society. In this study, a Bayesian network (BN) model was used to construct the supply-demand risk assessment framework, identify the risk factors during different periods in the Beijing-Tianjin-Hebei (BTH) region, and simulate the probability of supply-demand risk under different scenarios. The results showed that (1) the WEF supply-demand risk in the BTH region originated from not only core system factors, but also from external system factors. (2) The factors affecting the WEF supply-demand risk varied significantly over time. In the tortuous development stage (1989–1998), industrial and agricultural water use intensity were highly important. In the rapid development stage (1999–2008), the population growth rate became the main factor. In the coordinated development stage (2009–2018), the water and food supply-demand risks became increasingly important. (3) In scenarios where representative climate-economy-society factors (rainfall, gross domestic product, and population) were in high-high-high, medium-high-high, low-medium-high, and low-high-high, respectively, the probability of WEF supply-demand risk increased significantly. This probability was effectively reduced in medium-low-low, medium-medium-low, and medium-high-low scenarios. Using BN to study the WEF supply-demand risk allows for an intuitive understanding of the interaction mechanisms among variables in the WEF nexus. This approach also enables the design of more realistic scenarios, thus providing a reference for the formulation of early risk warning mechanisms.