Exploring interactions in the local water-energy-food nexus (WEF-Nexus) using a simultaneous equations model

Exploring interactions between factors is a critical step to understand, quantify and govern the WEF-Nexus. However, current research mainly focuses on mapping causal loops and the hierarchy structure; equations in interaction exploration have been largely ignored. Using the panel data of China's 30 provinces from 2005 to 2016, this paper adopts a simultaneous equations model (SEM) to evaluate intensities between related factors in the local WEF-Nexus. We define a local WEF-Nexus as containing core, peripheral and interactive sub-nexuses, and decouple the core sub-nexus from the supply, consumption and waste disposal processes. Results show that effective irrigated area, secondary industry rate and crop sown area are key positive influencing factors in the WEF subsystem, with positive impact coefficients of 1.0426, 0.6986 and 1.149, respectively. Food production (-0.303) and chemical fertilizer used per sown area unit (-0.3129) are key negative factors in the WEF subsystem. Additionally, urban green land (0.4436) and total population (0.5815) exert specific influences on the water and energy subsystems, with a 1% increase in urban green land resulting in a 0.4436% increase in water consumption. The system boundary, two positive feedback loops and seven nexus points are identified, with total groundwater pumping being the only nexus point exerting an holistic impact across the WEF equations. The results in this paper complement recent nexus modeling work, and give a better understand of interaction mechanism in China's local WEF nexus, with useful implications for future policy development.