Eleventh International Conference on Climate Change: Impacts & Responses

Abstract

Publicized during the Bonn COP23, coastal areas have particular ecological potential and are often hubs of natural disasters. Their attractiveness readable in the economy and population coastalisation, especially in the developing world including West Africa. Located on an island in the mouth of the Senegal River, Saint-Louis is an old French colonial settlement, frequently exposed to floods and coastal erosion. After the Sahelian drought, the construction of Diama and Manantali dams hugely impacted on the estuary hydro-sedimentary dynamics. In 2003, a significant flood threatening Saint-Louis, led Senegalese authorities to notch the Langue de Barbarie sandspit to permit water flow and spare it from flooding. Natural barrier protecting the Senegal river estuary, the Langue de Barbarie has become more exposed to coastal erosion and submersion threatening 825 inhabitants/km². Using remote sensing, geographical information system through digital shoreline analysis system, annual erosion rates have been calculated between 2003, 2010 and 2018. Saint-Louis vulnerability to floods have been mapped following the hydrogeomorphological methodology of digital flood areas model. Globally exposed to marine and fluvial erosion, the sandspit shows sectors of distal accretion, erosion that can be linked to an actual dyke construction to protect communities from recurrent floods by marine submersion. The lowest, between 0 and 1.75m (flooding alert in Saint-Louis) are located on Langue de Barbarie, in Saint-Louis peripheral districts. The Saint-Louis case is a grim picture of how anthropogenic footprint amplifies impacts of flooding and erosion in the actual context of sea level rise and climate changes.