From center to outlying areas: Navigating built-up land dynamics along urban-rural gradients in Global South megaregions

Understanding the dynamics of built-up land amidst the urban-rural transformation process is crucial for balancing the benefits of urbanization against the challenges of uncontrolled expansion. Yet, how built-up land develops across different types of human settlements, particularly within emerging Global South megaregions (GSMs), is not well documented. Employing an urban-rural gradient (URG) approach, we investigate built-up land dynamics across six representative emerging GSMs spanning 1985–2020, contextualizing our findings within urbanization theory and sustainable development discourse. Our analysis reveals that urban center growth and peri-urbanization drive a substantial proportion of built-up land expansion (36.47% and 27.39%, respectively), in contrast to the minimal increases observed in rural clusters and semi-dense areas (2.48% and 2.44%, respectively). The predominant expansion mode is sprawling growth, notably evident in peripheral areas, while densifying growth is mainly confined to urban centers and mostly uninhabited areas. Sprawling shrinkage is observed in dense and semi-dense urban areas, as well as rural clusters. These nuanced dynamics illustrate the varied ways in which regional territories engage with and are shaped by the urbanization process. Through the lens of the URG analysis, our study enhances understanding of spatial transformations in the GSMs, offering informative insights for fostering sustainable cities and human settlements.