Urban expansion-flood damage nexus: Evidence from the Dosso Region, Niger

Maurizio Tiepolo, Andrea Galligari, DIST-Politecnico and University of Turin, Italy
Published in: Land Use Policy, 108 (2021), Elsevier
Date: May 25, 2021

The current literature links flood exposure and the consequent damage in the sub-Saharan Africa to urban expansion. The main implication of this pertains to the fact that cities are the target of flood risk reduction. However, our knowledge of the built-up area expansion–flood damage nexus is still too scarce to support any risk reduction policy at the local scale. The objective of this study is to reconsider the link between urban expansion and flood damage widening the observation to rural settlements with open access information alternative to global datasets on flood damages and moderate resolution satellite images. Using very high-resolution satellite images accessible via Google Earth Pro, the expansion of 122 flooded settlements in the Dosso region (Niger) during the past 20 years is evaluated. Spatial dynamics is then compared with the rate of collapsed houses due to flooding. Finally, house collapses and retrofitting are compared. We discovered that cities expand at faster rates and with an opposite trend to that reported by the global datasets. However, hamlets and villages expand even more rapidly and suffer more house collapses than rural towns and cities. House consolidation is quicker than the settlement expansion but this is not sufficient to reduce damage from pluvial flooding. The proportion of the Poor to the total number of inhabitants in rural settlements is three times higher than that in urban settlements. Environmental justice is, therefore, not just an urban issue but a rural urgency.