Coupling Coordination and Projection of the Urban-Ecological Composite System Along the Beijing-Hangzhou Grand Canal

Taking cities along the Beijing-Hangzhou Grand Canal as the research subject, this study constructs urbanization and ecological environment indices to examine changes in urbanization and ecological environment in these cities from 2008 to 2024. First, an urbanization index and an ecological environment index were constructed for cities along the Beijing-Hangzhou Grand Canal. The spatiotemporal trends of these indices were analyzed. Subsequently, a coupling coordination model was developed to examine how coupling coordination levels evolve. Finally, a GM(GM (1,1) model was used to forecast future trends in coupling coordination levels. The conclusions are as follows: (1) Urbanization along the canal advanced rapidly and consistently. In contrast, the ecological environment followed a slow recovery and eventual steady improvement. Although the coupling coordination status historically improved from “barely coordinated imbalance” to “primary coordination,” the ecological subsystem consistently lagged behind. (2) Spatially, coordination levels show clear “core-periphery” and “south-high, north-low” disparities. High-coordination clusters are centered in the Yangtze River Delta urban agglomeration, while low-coordination zones are concentrated in western Shandong and southeastern Hebei, with these spatial clustering effects growing stronger over time. (3) Projections from the GM (1,1) model suggest that, under a natural evolution scenario, the entire canal region will reach an “intermediate coordination” phase by 2030. However, significant internal disparities are expected to persist.