The call comes as Africa’s urban population is expected to triple to almost[i] 1.5 billion by 20501. Meanwhile, nearly half (44%) of all “disaster events” globally have been flood-related, with 676 floods across Africa between 2001 and 2018, which have caused $6.3 billion worth of damage.[ii] In many African cities, more than half of the population live in informal settlements, which brings unique planning and design challenges and a significant population whose homes are especially vulnerable to floods.[iii]
To create the calculations, Arup’s team used an advanced digital tool, Terrain, which applies machine learning and artificial intelligence techniques to accurately quantify the amount of green infrastructure (e.g., grass, trees) and blue (e.g., ponds, lakes), versus the amount of grey (e.g., buildings and hard surfaces). The snapshot was based on detailed satellite imagery covering an area of approximately 150 square kilometres of the city’s main urban centre. Authors supplemented this analysis with insight on soil types and vegetation, enabling them to estimate how much rainwater would be absorbed in a defined heavy rainfall event.
