BEHAVIOR OF THE PHENOMENON OF COASTAL EROSION AFTER THE COMPLETION OF PROTECTION WORKS IN THE EAST OF SIAFATO IN COTONOU

In order to curb coastal erosion of the east of the SIAFATO spit in Cotonou, seven dykes were constructed. The study aims to analyze the evolution of the coastline after the construction of the seven dykes located in east of the SIAFATO dyke. To achieve this, several topographic survey phases using dual-frequency GPS were performed. The analysis of the 2012 and 2015 ridge lines indicated a sharp decline in the coastline between the SIAFATO dyke and the dye 7. The study conducted in 2017 reports shoreline stabilization in most cells when comparing the 2015 and 2017 ridge lines. The coastlines of 2017 indicate a sea advance on the continent ranging from 6m to 11m compared to those obtained in 2015. Downstream of the dyke 7, the erosion rate calculated is of the order of 26 m / year contrary to 35 m / year obtained during the 2015 studies. It follows that the advancement of the sea is not linear. Nevertheless, these results mark the vertiginous pursuit of erosion in this unprotected coastline. It is urgent to take bold measures to safeguard the property assets in this part of the coast.