58
C.T. Koulibaly, J.O. Ayoade
showed that the coastline from Bel Air to Rufisque was subject to annual erosion
of 0.6 m/year by using rectified aerial photographs of 1968–1997. The same process
was used by Guerin [22] to detect a coastline retreat of 0.77 per year. However, nowa‑
days, the availability of satellites imageries as well as the various automatic methods
of geospatial analysis has positively contributed to the monitoring of coastal disas‑
ters such as coastal erosion. This study thus proposes a newer approach of coast‑
line change assessment using Satellite imageries and the Digital Shoreline Analysis
System (DSAS). It analyzes the spatiotemporal dynamics of coastline retreat in the
locality of Rufisque from 1978 to 2018 at ten year intervals, while determining the
adaptation measures of local communities.
2. Materials and Methods
2.1. Study Area
Originally, Rufisque was a Lebou fishing village called Tenguedj (Wolof:
Tëngéej) and became important in the 16th century as the principal port of the king‑
dom of Cayor, being frequented by colonial masters. Its population was estimated
at 179,797 in 2002 and 490,694 in 2013 and the ethnic groups of Wolofs, principally
Lebous fishermen, are mostly represented [23: pp. 20–22].
Rufisque belongs to the geological area of the Cape Verde peninsula. It is locat‑
ed 25 km from Dakar and spans about 42 km². According to Dubresson [24], the area
of Rufisque results from tectonics (Paleocene horts of Ndiass and Dakar, exposure
of the Lutetian marl-limestone substratum in the Miocene) as well as volcanic erup‑
tions accompanying recent breaks. Its attachment to the main body of the Senega‑
lese basin probably emanates from sea level’ pulsations and climatic oscillations of
the Quaternary. The evolution of the basin was indeed subject to different phases
of marine transgressions and regressions responsible of a diversity of sedimentary
formations: from the Cretaceous to the Paleocene, essentially sandstone-clay marine
formations. From Paleocene to Eocene a general regression giving a biochemical sed‑
imentation (clayey-marly) which gradually becomes continental, containing inher‑
ited lateritic alterations [25]. Its geographical position, oceanic frame and influence
of North-North-East marine trade winds is favoring the maintenance of Guinean
affinities flora with specific environment including cool temperatures from January
to February [25].
Figure 1 shows a global presentation of the department of Rufisque with its
main coastal localities and boundaries.
Fishing still remains one of the major activities and the town also offers oppor‑
tunities of tourism because it conserves significant core of buildings in the French co‑
lonial style. Figure 2 illustrates the conserved colonial constructions of the main city
of Rufisque with their characteristic wrought-iron balconies and arcades, pitched
roofs of imported clay tiles.
C.T. Koulibaly, J.O. Ayoade
showed that the coastline from Bel Air to Rufisque was subject to annual erosion
of 0.6 m/year by using rectified aerial photographs of 1968–1997. The same process
was used by Guerin [22] to detect a coastline retreat of 0.77 per year. However, nowa‑
days, the availability of satellites imageries as well as the various automatic methods
of geospatial analysis has positively contributed to the monitoring of coastal disas‑
ters such as coastal erosion. This study thus proposes a newer approach of coast‑
line change assessment using Satellite imageries and the Digital Shoreline Analysis
System (DSAS). It analyzes the spatiotemporal dynamics of coastline retreat in the
locality of Rufisque from 1978 to 2018 at ten year intervals, while determining the
adaptation measures of local communities.
2. Materials and Methods
2.1. Study Area
Originally, Rufisque was a Lebou fishing village called Tenguedj (Wolof:
Tëngéej) and became important in the 16th century as the principal port of the king‑
dom of Cayor, being frequented by colonial masters. Its population was estimated
at 179,797 in 2002 and 490,694 in 2013 and the ethnic groups of Wolofs, principally
Lebous fishermen, are mostly represented [23: pp. 20–22].
Rufisque belongs to the geological area of the Cape Verde peninsula. It is locat‑
ed 25 km from Dakar and spans about 42 km². According to Dubresson [24], the area
of Rufisque results from tectonics (Paleocene horts of Ndiass and Dakar, exposure
of the Lutetian marl-limestone substratum in the Miocene) as well as volcanic erup‑
tions accompanying recent breaks. Its attachment to the main body of the Senega‑
lese basin probably emanates from sea level’ pulsations and climatic oscillations of
the Quaternary. The evolution of the basin was indeed subject to different phases
of marine transgressions and regressions responsible of a diversity of sedimentary
formations: from the Cretaceous to the Paleocene, essentially sandstone-clay marine
formations. From Paleocene to Eocene a general regression giving a biochemical sed‑
imentation (clayey-marly) which gradually becomes continental, containing inher‑
ited lateritic alterations [25]. Its geographical position, oceanic frame and influence
of North-North-East marine trade winds is favoring the maintenance of Guinean
affinities flora with specific environment including cool temperatures from January
to February [25].
Figure 1 shows a global presentation of the department of Rufisque with its
main coastal localities and boundaries.
Fishing still remains one of the major activities and the town also offers oppor‑
tunities of tourism because it conserves significant core of buildings in the French co‑
lonial style. Figure 2 illustrates the conserved colonial constructions of the main city
of Rufisque with their characteristic wrought-iron balconies and arcades, pitched
roofs of imported clay tiles.