'Flood risk reduction and climate change in large cities south of the Sahara'

In the region south of the Sahara, flooding is the most common natural hazard. Large cities are increasingly affected: 7 in the 1980s, 27 in the 1990s, 37 in the 2000s, and 7 more since 2010. Although many studies link this trend to climate change, our understanding of natural events is still too fragmentary to allow us to appreciate the correlation between precipitation and floods. When attempting to bridge this gap, we should also consider how rainfall affects a city’s entire watershed (which can be quite extensive). By contrast, the impact of flooding on places, goods, and people is much better understood. Such effects can be so extreme as to bring the economies of large cities to their knees. Over time, the concept of risk as a product of hazard and vulnerability has expanded to include exposure and climate change adaptation. Mapping flood risk is the first step towards identifying adaptation measures, yet only one of the 11 large cities most affected by floods has a detailed flood risk map. Three of the 11 have adopted climate change adaptation strategies and plans. The remaining eight cities use an array of tools whose impact on flood risk reduction is not yet detectable.