Chaigneau Alexis auteur aut IRD Okpeitcha O. V. auteur aut IRD Morel Y. auteur aut IRD Stieglitz Thomas auteur aut IRD Assogba A. auteur aut IRD Benoist Morgane auteur aut IRD Allamel Pierre auteur aut IRD Honfo J. auteur aut IRD Sakpak T. D. A. auteur aut IRD Retif F. auteur aut IRD Duhaut T. auteur aut IRD Peugeot Christophe auteur aut IRD Sohou Z. auteur aut IRD text journalArticle eng text/pdf born digital access This study investigated the main water-level (WL) variability modes of Nokoué Lagoon in Benin (West-Africa). The average WL ranges between 1.3 and 2.3 m between the low-and high-water seasons. Seasonal as well as weak interannual variations between 2018 and 2019 are driven by rainfall regime over the catchment and associated river inflow. At sub-monthly scales, the lagoon is tidally choked: ocean tides can reach 90 cm, whereas in the lagoon semi-diurnal and diurnal tides hardly reach few centimeters. Choking conditions vary with river inflow and ocean tide amplitude, correctly represented by a simple tidal choking model. Diurnal modulation and asymmetry of the tide are stronger (weaker) during high (low) water period. We also observed WL variations of +/- 5-10 cm at a fortnightly frequency, stronger during wet (high-water) season. Superimposed on the seasonal, fortnightly and tidal WL variations, we further observed short-term high-frequency seiche events. Mostly observed during dry (low-water) conditions, they are characterized by typical standing-wave oscillations of 5-10 cm amplitudes and 3 h periods. They are forced by the passage of fast-moving squall-lines that induce strong wind variations, heavy rainfalls and rapid drop-off of the air temperature. Results obtained in this study provide useful metrics for the validation of flood forecasting models to be implemented in Benin, and elsewhere on the West African coastline. specialized Water -levels Lagoons Tides Seiches Nokoué Wavelet analysis BENIN GOLFE DE GUINEE ZONE TROPICALE NOKOUE LAC 032 062 021 267 107767 [12 p.] 2022 0272-7714 https://www.documentation.ird.fr/hor/fdi:010087433 10.1016/j.ecss.2022.107767 0272-7714 [F B010087433] https://www.documentation.ird.fr/hor/fdi:010087433 https://www.documentation.ird.fr/intranet/publi/2023-04/010087433.pdf Accès réservé (Intranet de l'IRD) IRD - Base Horizon / Pleins textes 2023-04-14 2025-02-24 fdi:010087433 fre