Coupling Coordination as a System Condition: Industrial Structure Optimisation, Land-Use Efficiency, and Urban Economic Resilience in China’s Urban Agglomerations

Urban agglomerations are complex systems in which industrial, land, and economic subsystems coevolve. Using panel data from 48 cities in the Beijing–Tianjin–Hebei, Yangtze River Delta, and Pearl River Delta agglomerations from 2013 to 2023, this study examines how industrial structure optimisation (ISO) relates to urban economic resilience and how industrial land-use efficiency (ILUE) conditions this relationship. The coupling coordination degree (CCD) between ISO and ILUE is used to describe subsystem coordination states. The results show that ISO is positively associated with resilience in the full sample and in both Beijing–Tianjin–Hebei and the Yangtze River Delta, while the coefficient is positive but not significant in the Pearl River Delta. ILUE significantly strengthens the ISO–resilience relationship. CCD-based subgroup analysis further suggests a state-dependent pattern: in low-CCD systems, ISO and ILUE exhibit significant independent effects, whereas in high-CCD systems, these direct effects weaken and resilience gains are concentrated in their joint configuration. The moderating effect is significant across all three agglomerations and is particularly pronounced in the Pearl River Delta. These findings indicate that the resilience effects of industrial upgrading depend not only on land-use efficiency, but also on the coordination state of the industrial–land system.