Delineating urban growth boundaries by coupling urban interactions and ecological conservation

Urban growth boundaries (UGBs) are efficient tools for controlling disorderly urban expansion/sprawl and ensuring sustainable urban development. Previous studies have delineated UGBs from the perspective of ecological conservation or efficiency improvement and have widely applied them to spatial planning. However, few studies have investigated the role of urban interactions and connections in delineating UGBs, especially in rapidly developing urban agglomerations. Our study proposed a novel framework for UGBs delineation in urban agglomerations by coupling urban interactions and ecological conservation, with two innovative points. First, interurban interactions and connections were quantified to elucidate the transition rules of cellular automata (CA), and ecological conservation was configured as a constraint of the CA model. Second, the hierarchical generalized linear model (HGLM)-CA model was used to simulate the urban land pattern in 2035, and the dilation-erosion algorithm realized the final UGBs. The proposed framework was applied to UGBs delineation in the Changsha-Zhuzhou-Xiangtan (CZX) urban agglomeration, a rapidly developing urban agglomeration in China. Furthermore, a comparison among multi-scenario UGBs shows that urban interactions and connections can accelerate the clustering of urban development, and the delineated UGBs are more practical. Our study highlighted the importance of urban interactions for UGBs delineation in urban agglomerations and evaluated a case of UGBs delineation to validate our appeal.