Evolution of Beninese Coastline from 1963 to 2005: Causes and Consequences

The coastal zone of Benin is the interface between the marine environment and the straightforward continental environment. It is constituted of sandy cords, lagoon system, lakes and flood plains. This zone shelters a population of about 3 million inhabitants that is more than 30% of the Beninese population. As all coastal regions of the world, this zone remains very sensitive to climatic changes (global elevation of the sea level, perpetual variations of the weather marines conditions) and to human activities (large inland dams, harbour infrastructures, urbanization) that drive to the rupture of the equilibrium in this coastal environment with enhanced risks of beach erosion as the main consequences. This study monitors the evolution of the Beninese shorelines around Cotonou and underlines the causes mainly human that negatively affect this naturally fragile environment. Natural factors (tempests and erosive processes) and human actions (building of the port of Cotonou (1962) then Lome (1967) and hydroelectric dams on Volta (1966) and on Mono (1987) rivers) aim the coastal evolution of the Benin. They procreate, on the sandy cords at East of ports and rivers mouths, an erosion about 10 m linked to the reduction of provisions in sand and the fragilisation of cords by farms, steps and of anarchic occupations.