Delineating urban growth boundaries under multi-objective and constraints

Urban growth boundaries (UGBs) have viewed as an efficient tool to control disorderly urban expansion and promote urban sustainable development. The existing methods related to UGBs delineation have also focused mainly on improving the efficiency and applicability of the methods. However, it is not enough to emphasize simply the superiority of the methods, especially in China. UGBs delineation not only considers regional heterogeneous resource endowments but also further coordinates pre-existing land-use plans and the conflicts with one another. The study presents a novel framework for delineating UGBs from carrying-capacity-oriented perspective whose contributions are twofold. Firstly, the level of carrying capacity on resource and environment for each sub-region was evaluated by carrying capacity analysis. A modified mechanism was used to coordinate the inter-regional trade-off between urban growth and carrying capacity on resource and environment and quantify as the constraints of the algorithm. The suitability evaluations of multiple land-use type, including urban lands, agricultural lands, and ecological lands, are viewed as the optimization objectives of the algorithm together with urban landscape compactness. Second, we develop a comprehensive method coupling carrying capacity analysis, land-use suitability evaluation, and modified ant colony optimization algorithm. It can not only coordinate the conflicts with the land-use plans but also ensure the sustainable development for each sub-region. The dilation and erosion algorithm generates optimal UGBs. The proposed framework was applied to UGBs delineation in Wuhan, a rapidly urbanizing city in China. Multi-scenarios UGBs were delineated by the proposed framework. The results demonstrated carrying-capacity-oriented UGBs delineation perspective is more practical and closer to reality than the results of traditional methods. The conceptual and methodological advancement of this study is applicable to other cities to assist UGBs delineation.