Urban expansion and form changes across African cities with a global outlook: Spatiotemporal analysis of urban land densities

Abstract

Africa has been experiencing rapid urbanization, yet limited studies have systematically investigated urban growth dynamics across African cities. Using 25 cities as cases, we quantified urban growth and form changes in Africa via spatiotemporal analysis of urban land densities in concentric rings over three time points (1990, 2000, and 2014). The results show that African cities have rapidly grown both in population and built-up areas, which increased by about 4% and more than 5% per annum, respectively. Urban land density (defined as the proportion of the built-up area to the buildable area) in each concentric ring decreases from the city center to the urban periphery with diverse patterns..