Unraveling the Spatial Heterogeneity of WEFE Nexus: The Vulnerable Ecological Hub and Policy Implications in the Yangtze River Delta

The intertwined challenges of water, energy, food, and ecosystem security (WEFE) critically constrain sustainable development, demanding a holistic nexus framework. Though extensively studied, existing WEFE models lack a systemic network perspective, obscuring complex interrelations and hindering targeted governance. Building on a comprehensive evaluation of WEFE dimensions, this study applied network analysis to examine the WEFE nexus across 26 cities in the Yangtze River Delta (YRD) from 2000 to 2023, utilizing network metrics to characterize network structures. The results revealed concerning WEFE trajectories, as energy security (EnS) collapsed across all cities, food security (FS) exhibited increasing polarization between northern and southern cities, ecological security (EcoS) significantly degraded in over 76% of cities (notably in Shanghai, Suzhou, and Wuxi), while water security (WS) remained stagnant. Spatial heterogeneity emerged in the WEFE nexus networks, with a pronounced EnS‐EcoS synergy in the 18 northern cities, whereas southern and western areas showed complex interrelationships. Synerg sub‐network density varied considerably among cities, ranging from 0.077 to 0.294, while trade‐off sub‐network density remained low and sporadic, suggesting that synergistic interactions predominated over trade‐off ones in most regional subsystems. EcoS was the key node in 21 cities, but its pervasive degradation signals a profound systemic vulnerability, wherein its deterioration risks triggering cascading failures throughout the entire nexus. Finally, a spatially explicit governance framework was proposed to safeguard key nodes, amplify synergies and alleviate trade‐offs. By pinpointing the WEFE's spatial heterogeneity and complex interrelationships, this study provides a scientific foundation for fostering coordinated regional security in the YRD.