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Impacts of the storm surges on sandy beaches: example of northern coast of Dakar (Senegal).

Beach, Beach profile, Dunes, Erosion, Morphological. Coastal spaces offer many development opportunities to human societies. However, their management is faced with major challenges such as coastal erosion among others which constitute a great constraint for their development. In Senegal, the methods of studying the dynamics of these spaces are often based on a diachronic analysis of satellite images or aerial photographs over several decades. These methods, which allow to get an idea of the evolution rates of shorelines, often do not take into account the impact of instantaneous events such as storm surges which can cause sudden and irreversible changes in coastlines. The cumulative impact can affect the long-term evolution of the shore. In order to assess the morphological impacts of the exceptional swells of November 2018 on the northern part of the Dakar coast, beach profiles were collected before and just after their passage at the beaches of Malibu, Gadaye and Malika. This allows to know the induced morphological variations as well as the volumes of mobilized sediments. The results of this monitoring show that these swells have a significant erosive impact with a higher amplitude in Malibu where the entire beach profile has been affected. At the beaches of Gadaye and Malika, erosion has only affected their aerial part. This erosion has led to the erection of micro cliffs at the bottom of the dunes, the disappearance of the upper beach and a change in the shape of the beach profile, causing the slopes to variation. This strong erosion associated with temporary flooding of a good part of the back beach can be linked, in addition to the scale of the swell, the low topography of the environment, the small widths of the beaches and their open nature due to no obstacle for swells

Auteur(s) : Papa SAGNE, Boubacar FALL, Kader BA, Gayane Faye, El Hadji SOW, Isabelle NIANG
Pages : 325–335
Année de publication : 2020
Revue : EWASH & TI Journal
N° de volume : 4 (1)
Type : Article
Mise en ligne par : SOW El Hadji