Castelle B., Almar Rafaël, Dorel Matthieu, Lefebvre Jean-Pierre, Senechal N., Anthony E. J., Laibi R., Chuchla Rémy, Penhoat Yves du. (2014). Rip currents and circulation on a high-energy low-tide-terraced beach (Grand Popo, Benin, West Africa). Journal of Coastal Research, (no spécial 70), p. 633-638. ICS 2014 : International Coastal Symposium, Durban (ZFA), 2014/04/13-18. ISSN 0749-0208.
Titre du document
Rip currents and circulation on a high-energy low-tide-terraced beach (Grand Popo, Benin, West Africa)
Année de publication
2014
Auteurs
Castelle B., Almar Rafaël, Dorel Matthieu, Lefebvre Jean-Pierre, Senechal N., Anthony E. J., Laibi R., Chuchla Rémy, Penhoat Yves du
Source
Journal of Coastal Research, 2014,
(no spécial 70), p. 633-638 ISSN 0749-0208
Colloque
ICS 2014 : International Coastal Symposium, Durban (ZFA), 2014/04/13-18
Rip currents are wave-driven intense seaward-flowing jets of water that are important to both beach morphodynamics and the overall ecosystem. Rip currents are also the leading deadly hazard to recreational beach users worldwide. More specifically, the African region is reported to have the highest rates of drowning in the world, yet both the occurrence and the type of rips developing along the African beaches are unknown. In February 2013, a 12-day field experiment was performed at the high-energy low-tide-terraced sandy beach of Grand Popo beach (Benin, West Africa). Human drifter data and video imagery are combined to address wave-driven circulation and rip current activity. Results show two prevailing rip current types. (1) Low-energy (similar to 0.2-0.4 m/s) swash rips, with short life-spans of about 1 minute, extend about 5-10 m offshore and occur preferably at mid to high tide at fixed locations in the center of beach cusps. (2) Higher-energy (0.2-.8 m/s) surfzone flash rips become active with the onset of intense wave breaking across the low-tide terrace. They tend to migrate downdrift with a longer time-span of about 2-5 minutes. The relatively weak longshore current (0.2 - 0.55 m's) measured during the experiment suggests that flash rips were driven by vortices generated by wave breaking rather than shear instabilities of the longshore current. Swash rips and flash rips are common at Grand Popo and often co-exist We propose a conceptual model of both flash and swash rip activity on this stretch of the West African coast
Plan de classement
Limnologie physique / Océanographie physique [032]
Description Géographique
BENIN
Localisation
Fonds IRD [F B010063185]
Identifiant IRD
fdi:010063185
