56
C.T. Koulibaly, J.O. Ayoade
1. Introduction
Sea level rise is one of the major consequences of global warming. It is mainly
due to the thermal expansion of oceans, the melting of mountain glaciers as well as
margins of Greenland’ ice caps and Antarctica [1]. “However, as the rate of sea-level
rise accelerates, it may increasingly become the driving force in coastal changes” [2].
Accelerated rates of sea level could cause the flooding of low-lying land, saltwa‑
ter intrusion into groundwater and streams, increased extent and severity of storm
flooding, and coastal erosion.
With over 700 km of coastline, Senegal is located at the western point of the
African continent. In addition to the huge biodiversity characterizing this coastline,
it provides important goods and services to the local economy. These 700 km of
coastal zones are widely open to the Atlantic Ocean and can be described as fol‑
lows; 300 km of sandy coast; 234 km of mangroves and estuary zones and 174 km
of rocky coast. This situation makes it susceptible to phenomena such as inundation
and coastal erosion. “Observed shoreline erosion rates vary with location, but are on
average between one and two meters per year for sandy beaches, and 0.1 m to 0.7 m
for rocky coasts in Senegal” [3: pp. 7–8]. In addition to this, “More than 50 percent
of the coastline is at high risk while 25 percent of Senegal’s coast is at high risk of
coastal erosion from rising sea levels” [4]. In less than (50) years, an average decline
of 1 to 1.30 m/year has been observed causing loss of settlements and infrastructures
particularly in the “Cape Verde peninsula”, the “Grande Côte” and “Petite Côte”.
The locality of Rufisque is particularly sensitive to coastal erosion. Between 1933
and 1988, coastline retreat was estimated at 1.30 m [5: pp. 53–82]. However, the pro‑
tective walls have intensified the recession rates of Rufisque shoreline especially at
the extremities of these structures, causing rapid erosion at the seafront of the local
graveyard and threatening houses and other economic infrastructures. According to
Niang et al. [6], a 1 m sea level rise would result in the disappearance of 46–63% of
beaches by coastal erosion and 3.5–25% of the area by inundation. In some areas like
Bargny, fishing communities are experiencing serious losses of amenities due to fre‑
quent storm surges. About 300 buildings housing almost 2250 dwellers are estimat‑
ed to be impacted by 2080 [3]. According to Drammeh [7: pp. 43–46], recent studies
conducted by International Union for Conservation of Nature through a comparison
between the positions of the high water mark limit on aerial photographs and satel‑
lite images between 1954 and 2006, shows a significant regression of Rufisque’ beach
from 0.4 to 1.5 m/year.
Studies on coastal erosion have indeed gained particular attention from re‑
searchers using different approaches. Through a simple comparison of the posi‑
tion of shorelines from different dates, the European Commission [8] concluded
that erosion affects 40% of the beaches of the European Union and more than 50%
of sandy coasts in France. In the United States, the comparison of historical shore‑
lines of (1800s, 1930s, 1970s) with the operational mean high-water shoreline has
C.T. Koulibaly, J.O. Ayoade
1. Introduction
Sea level rise is one of the major consequences of global warming. It is mainly
due to the thermal expansion of oceans, the melting of mountain glaciers as well as
margins of Greenland’ ice caps and Antarctica [1]. “However, as the rate of sea-level
rise accelerates, it may increasingly become the driving force in coastal changes” [2].
Accelerated rates of sea level could cause the flooding of low-lying land, saltwa‑
ter intrusion into groundwater and streams, increased extent and severity of storm
flooding, and coastal erosion.
With over 700 km of coastline, Senegal is located at the western point of the
African continent. In addition to the huge biodiversity characterizing this coastline,
it provides important goods and services to the local economy. These 700 km of
coastal zones are widely open to the Atlantic Ocean and can be described as fol‑
lows; 300 km of sandy coast; 234 km of mangroves and estuary zones and 174 km
of rocky coast. This situation makes it susceptible to phenomena such as inundation
and coastal erosion. “Observed shoreline erosion rates vary with location, but are on
average between one and two meters per year for sandy beaches, and 0.1 m to 0.7 m
for rocky coasts in Senegal” [3: pp. 7–8]. In addition to this, “More than 50 percent
of the coastline is at high risk while 25 percent of Senegal’s coast is at high risk of
coastal erosion from rising sea levels” [4]. In less than (50) years, an average decline
of 1 to 1.30 m/year has been observed causing loss of settlements and infrastructures
particularly in the “Cape Verde peninsula”, the “Grande Côte” and “Petite Côte”.
The locality of Rufisque is particularly sensitive to coastal erosion. Between 1933
and 1988, coastline retreat was estimated at 1.30 m [5: pp. 53–82]. However, the pro‑
tective walls have intensified the recession rates of Rufisque shoreline especially at
the extremities of these structures, causing rapid erosion at the seafront of the local
graveyard and threatening houses and other economic infrastructures. According to
Niang et al. [6], a 1 m sea level rise would result in the disappearance of 46–63% of
beaches by coastal erosion and 3.5–25% of the area by inundation. In some areas like
Bargny, fishing communities are experiencing serious losses of amenities due to fre‑
quent storm surges. About 300 buildings housing almost 2250 dwellers are estimat‑
ed to be impacted by 2080 [3]. According to Drammeh [7: pp. 43–46], recent studies
conducted by International Union for Conservation of Nature through a comparison
between the positions of the high water mark limit on aerial photographs and satel‑
lite images between 1954 and 2006, shows a significant regression of Rufisque’ beach
from 0.4 to 1.5 m/year.
Studies on coastal erosion have indeed gained particular attention from re‑
searchers using different approaches. Through a simple comparison of the posi‑
tion of shorelines from different dates, the European Commission [8] concluded
that erosion affects 40% of the beaches of the European Union and more than 50%
of sandy coasts in France. In the United States, the comparison of historical shore‑
lines of (1800s, 1930s, 1970s) with the operational mean high-water shoreline has