Construction land allocation in Beijing-Tianjin-Hebei and Yangtze River Delta urban agglomerations

Regional development strategies that align with urban characteristics and the scientific allocation of construction land indicators can effectively guide the high-quality coordinated development of urban agglomerations. However, the issue of whether urbanization matches the development strategy has always lacked an in-depth response in geography.Moreover, along with the urbanization process, the land limitation for agricultural and ecological spaces becomes increasingly strict, and the availability of construction land indicators is increasingly constrained. The construction land allocation is thus critical for the distribution of regional resources and the development goals of urban agglomeration. Based on the principles of development geography and the core-periphery theory, this study comprehensively considered three subsystems of urbanization(population, economy, and land) and the spatial link intensity among cities within a certain region to analyze the impacts of “siphon” and “radiation” effects on regional development, and assessed whether China's two major regional urbanization strategies aligned the comprehensive development characteristics. Furthermore,the quantitative construction land allocation in Beijing-Tianjin-Hebei(BTH) and Yangtze River Delta(YRD) urban agglomerations was completed. The results showed that the urban comprehensive level index(UCL) in core cities(Beijing and Tianjin) and peripheral cities differed significantly in BTH, demonstrating a clear core-periphery structure. Along with urbanization,the “siphon” effect in BTH was weakening. Beijing's urban primacy decreased and the growth rate of UCL decreased from 53.89% in the first five years to 18.37% in the last five years during the study period(2020–2019). In contrast, the “radiation” effect in YRD was more obvious, exhibiting a development pattern driven by multiple growth poles. Temporally, the BTH indicated a coordinated development trend, while the integration level of YRD continued to strengthen. Compared to the top-down construction land allocated by the government, the results of quantitative allocation in this study reduced volatility. This study confirms the scientific basis of the coordinated development for BTH and the integrated regional development strategy for YRD from the perspective of development geography. It also provides a practical reference for the construction land allocation.