QUANTIFYING THE MORPHOLOGY OF AFRICAN CITIES

Rafael Prieto-Curiel (Personal webpage)

Most parts of Africa's infrastructure are yet to be built. Where and howthese new buildings are constructed matters since today's decisions willlast for decades. Satellite imagery enables the construction of urbanform indicators to compare African cities' elongation, sprawl andemptiness. We characterise urban morphology based on the distributionand size of millions of buildings in African cities. Many cities areelongated or sprawled, especially urban areas dominated by smallbuildings or close to physical barriers or international borders.However, as the population increases, distances grow and becomecritical, so cities experience intense competition for space and betteruse it. Larger cities tend to settle more efficiently. For each city, wemeasure the mean inter-building distance, a proxy for energy consumptionrelated to urban mobility. Distances inside a city grow faster than thesquare root of its population, resulting from the combined impact of asublinear growth in the number of buildings and a sublinear increase inbuilding size and urban form indicators. We show that when a citydoubles its population, it roughly triples the energy demand related tocommutes.