Urban Land Use Efficiency and Spatial Dynamics: A Case Study of Nanjing’s Sustainable Development

In recent years, urban sustainable development has been increasingly emphasized by various local governments. In order to investigate the development situation in Nanjing, this study extracted the urban built-up areas for the years 2000, 2005, 2010, 2015, and 2020. The GDP data and built-up area were then used to calculate the sustainable development indicator 11.3.1. The results indicate that the urban areas of Nanjing have expanded significantly, with an increasing trend in expansion speed. The predominant morphology of Nanjing’s urban area involves outward expansion and internal infilling, leading to a continuous decrease in spatial compactness and a stabilization of spatial form. The centroid of Nanjing’s built-up area has expanded towards the northeast and southwest directions. Based on the results of built-up area extraction, further calculations were conducted for SDGs 11.3.1 indicators and an analysis of land use efficiency. The findings indicate that from 2000 to 2005, there was a significant increase in land consumption in Nanjing, while the rate of land expansion slowed down from 2010 to 2020. The rapid population growth in 2010 can be attributed to the strong economic development that attracted external migrant workers and the implementation of policies promoting population openness. In terms of the SDGs 11.3.1 indicator, the built-up area in Nanjing experienced a temporary slowdown in growth, but maintained a stable upward trend, indicating effective government control over land expansion. This study, utilizing built-up area extraction for SDGs 11.3.1 indicator calculation and land use efficiency analysis, assesses the sustainability of urban development. The results suggest that the government has implemented effective measures to control land expansion. The scientific insights derived from this research provide valuable recommendations and assessments for the future development of urban clusters.