Evolution Patterns and Impact Mechanisms of Water–Energy–Food Nexus Evaluation in Arid Regions from a Water Footprint Perspective

The water–energy–food nexus (WEF nexus) is central to sustainable development in arid regions. However, research on nexus evolution based on water consumed during food and energy production remains limited. In this study, the evolutionary patterns and influencing mechanisms of the WEF nexus in an arid region are investigated from a water footprint perspective, taking the middle reaches of the Yellow River Basin in China as a case study. The results show that from 2010 to 2021, the crop water footprint in the study area exhibited distinct varietal differences, with the highest values for legumes and the lowest for tubers, and a spatial pattern characterized by higher values in the north and lower values in the south. The energy–water footprint underwent a structural shift from grey water dominance to blue water dominance in 2015. The coupling coordination degree of the WEF nexus gradually improved from moderate imbalance to mild imbalance. The core obstacle in the water subsystem shifted from water quantity shortage to an imbalance in water use structure, while that in the energy subsystem moved from supply-side constraints to consumption-side constraints. The food subsystem was constrained by rigid factors related to arable land and ecological conditions. Consequently, the core constraint of the WEF nexus has transitioned from independent bottlenecks within individual subsystems to cross-system coupling constraints. Regulating the water footprint on both the production and consumption sides is conducive to the sustainability of the WEF nexus. The findings of this study enrich the regional empirical evidence of the nexus theory and provide a reference for research and practice concerning the optimal allocation of regional resources.