A peninsula in coastal erosion ? Dakar, the Senegalese capital city facing the sea level rise in the context of climate change

Abstract

This study focuses on the shoreline evolution that occurred along the Senegalese capital city during a sixty-one year period by photo-interpretation. Shoreline data from 1954, 1980, 1997, 2006 and 2015 were incorporated in Geographic Information System (GIS) using Digital Shoreline Analysis System (DSAS) for analysis. The average rate of erosion in beach surface has been estimated to -2.33 m / year ± 0.04 m / year between 1954 and 2015. The average rate of accretion has been limited to some localized zones towards Thiaroye Guédj (+ 0.80 m / year ± 0.04 m / year), Rufique (zone situated upstream of the channel of the thermal power station) with (+ 0.90 m / year ± 0.04 m / year) and Yene (+ 0.5 m / year ± 0.04 m / year). The average rate of erosion in beach surface has been increaed gradually until 2006 over the periods (-1.86 m / year ± 0.13 m / year between 1954 and 1980, - 3.86 m / year ± 0.17 m / year between 1980 and 1997, - 5.20 m / year). ± 0.41 m / year between 1997 and 2006 and - 4.79 m / year ± 0.31 m / year between 2006 and 2015). The causes are many and very diverse, they usually involve the conjunction of natural factors (swell, drift currents, tide, wind, sea level rise, soil erosion and sediment supply) and humans activities (urbanization, sand extraction and construction of inappropriate protection structures). The regression of the coastline, and consequently the surface losses along the coast, were seventeen times greater in the North (from Yoff to Den Gedj) than in the South (from Hann to Toubab Dialaw); however erosion is more felt by the people on the south coast. Despite this context of widespread erosion and intense urbanization, the government of Senegal has so far not adopted a law on the coastline.