Delineating rigid and elastic coupled urban growth boundaries to constrain spatial sprawl: A case study in central urban area of Zhengzhou, China

Urban development model is transitioning from disorderly sprawl to compact growth. In this process, urban growth boundary (UGB) is important for preventing excessive spatial expansion and optimizing land use structure. However, few existing studies have focused on delineation strategies that integrate both rigid and elastic UGBs. Taking Zhengzhou as a case study, we developed a framework for delineating rigid and elastic UGBs involving identification of basic farmland and ecological protection zone, evaluation of land suitability, and multi-scenario simulation of urban development. The results showed that urban space increased significantly by 210.56 km 2 from 2000 to 2020, which posed risks of imbalanced land use structure. Identified basic farmland and ecological protection zone covered 41.99 km 2 and 57.68 km 2 , respectively. Their scope was prohibited for urban construction and was used as guidance to delineate rigid UGB, which covered 712.21 km 2 . Sustainable development scenario was considered as dominant paradigm for urban development. Therefore, it was used as guidance to delineate elastic UGB, which covered 595.55 km 2 . These findings confirm the effectiveness of a delineation strategy that combines rigid and elastic UGBs in maintaining ecological security and constraining spatial sprawl. Additionally, technical references for delineating UGB are provided for cities facing compact growth demands.