Floc'h F., Aziayibor K., Almar Rafaël, Penhoat du Yves, Lefebvre Jean-Pierre, Dorel M., Delacourt C. (2018). Origin of sediment fluxes in inner shelf zone via acoustic measurements, Grand-Popo, Benin. Journal of Coastal Research, (81 No spécial), p. 107-113. ISSN 0749-0208.
Titre du document
Origin of sediment fluxes in inner shelf zone via acoustic measurements, Grand-Popo, Benin
Floc'h F., Aziayibor K., Almar Rafaël, Penhoat du Yves, Lefebvre Jean-Pierre, Dorel M., Delacourt C.
Source
Journal of Coastal Research, 2018,
(81 No spécial), p. 107-113 ISSN 0749-0208
In the Gulf of Guinea, energetic swells generated in South Atlantic are responsible for one of the most important littoral drifts in the world, directed Eastward. The construction of harbour dams along this littoral disturbs the natural balance of the system and causes extreme erosion up to 10 m/year. Within the framework of this study, a serie of intensive measurements was conducted at Grand Popo from March, the 10th to the 19th, 2014. A large number of hydrodynamic, sedimentary and morphological parameters were measured. The backscatter signal from an Acoustic Doppler Current Profiler (ADCP) colocalised with a turbidity meter is inverted emprirically. Three main events of suspension over the whole water column are observed, during intense wind (>5m/s) lasting more than 8 hours. Actually, the water surface entrains after about 3-4 hours of intense wind, then the momentum is advected to the bottom in 2 or 3 hours depending on the intensity of the wind. The turbidity is then directly linked to the bottom stress derived from the mean current. The longshore flux is thus due to wind and always Eastward. The cross-shore flux is alternatively directed onshore or offshore. During spring tide, the offshore flux is in phase with the beginning of the tide flow. The exact origin of the current was not identified. Longshore flux were found to be 20 times higher than cross-shore flux.
