Coastal erosion dynamics of Dakar, Senegal

Abstract

The advancing sea resulting from sea level rise, combined with the effects of climate change and hydrodynamic agents, is affecting the coastal morphology of the Dakar region. As a result, a reduction of coastal areas is observed in some coastal zones, causing human displacement inland and disrupting economic activities such as fishing and tourism. Coastal erosion makes the coasts of the Dakar region physically and socio-economically vulnerable. This study analyses the dynamics of the coastline from 1990 to 2040 using Geographic Information System techniques and shows that the region records average retreats of about -0.44 m/year, 0.21 m/year and -0.11 m/year respectively on the northern, western and southern coasts. These dynamic rates are expected to be about -4.4 m/year (for the north coast), 2.1 m/year (for the west coast) and -1.1 m/year by 2030 (south coast). By 2040, they are estimated to be around -8.8 m/year (north coast), 4.2 m/year (west coast) and -2.2 m/year (south coast). These predicted dynamic rates will result in a loss of coastal areas, estimated at 861273 m2 in 2030 and 1256493 m2 in 2040. These forecasts depend on the behavior of hydrodynamic agents and coastal characteristics. They also provide information on the level of vulnerability to coastline dynamics. The physical and socio-economic vulnerability of the Dakar region to coastal erosion was also studied using the Coastal Vulnerability Index method. It is shown that different vulnerability indexes are noted on the northern (94), western (10) and southern (23) coasts. Although the Dakar region is physically vulnerable to coastal erosion, it is essential to note that this vulnerability is accentuated by human activities which make it socio-economically vulnerable. This physical and socio-economic vulnerability also will negatively affect the economic land value of the coast in 2030 and 2040. Thus, the estimate of economic loss by the use of an econometric model shows that the Dakar coastline will record an estimated loss of 38,507,856,000 FCFA in 2030 and 57,822,698,000 FCFA in 2040. These forecasts would make it possible to prevent the impact of coastal erosion by installing protective infrastructure in the most exposed areas. Whether the Dakar region coastline is economically confronted with coastal erosion, abnormal settlements, pollution, sand exploitation aggravate economic losses. Several adaptation measures have been implemented. However, despite the efforts of the Senegalese government to combat coastal erosion, the coastline continues to retreat.