Effects of Protective Structures in Morpho-Sedimentological Changes： A Case Study of Rufisque＇s Coast, Petite C6te, Senegal

Protective structures, built in the 1980＇s in order to reduce or stop coastal erosion in Rufisque, involved a modification of the coastal morpho-sedimentary landscape and have intensified the coastal dynamics. The diachronic study of beach profiles, before and after the seawalls construction showed that these protective structures accentuated the coastal erosion, with more important sedimentary deficits at the ends of the structures. Today, the Rufisque coast is characterized by a set of sedimentary cells whose morphological evolution and annual sedimentary dynamics are controlled by seasonal forcing： sedimentary deposits in dry season and erosion in wet season. However, this alternation of deposits and erosion phase shows spatiotemporal disparities. These disparities are very marked between a northwestern area characterized by concave profiles and a southeastern area （the bay of Rufisque） characterized by convex profiles and a much more important sedimentary deficit. The results also showed that these methods of shoreline protection are not durable measurements （degradation of the structures） and have exacerbated the vulnerability to coastal erosion as well as those of the coastal populations.