TITLE:
Hydro-Sedimentary Dynamics of the Grand-Popo Lagoon Located Upstream of the Mobile Embouchure “Bouche du Roy” in South-Western Benin
AUTHORS:
Honorin Gbinibou Andemi, Gérard A. F. d’Almeida, Moussa Bio Djara, Léandre Accalogoun, Rodrigue A. Adechina, Christophe Kaki
KEYWORDS:
Grand-Popo Lagoon, Hydro-Sedimentary Functioning, Lagoon Bottoms, Sediments
JOURNAL NAME:
Journal of Geoscience and Environment Protection,
Vol.9 No.11,
November
29,
2021
ABSTRACT: The problems of flooding, bank erosion and even the
breaching of the barrier beach by the Grand-Popo lagoon are a concern in the
south-western Beninese river-lagoon complex. The present study aims to improve
the knowledge of the factors controlling the hydro-sedimentary functioning of
this lagoon of Grand-Popo. It was based on bathymetric and sedimentological
studies and the analysis of physical-chemical parameters of the water and
allowed to know the morphology of the lagoon bottom and the distribution of
sedimentary facies according to the intensity of the water current. The
salinity of the lagoon waters shows a west-east gradient passing thus from 0‰
to 0.78‰ in the main direction of flow. Over the whole lagoon system, the
average liquid flows vary from -38.499 to 159.13 m3/s. The
bathymetry indicates depths varying from 0.4 to 6.5 m, revealing type V and
type U lagoon bottoms which reflect acute bottom concavities marked by
hollowing under the effect of strong currents or by sandy terraces resulting
from the continuous input of sediments carried by the Mono River. These
sediments are heterogeneously distributed in the lagoon bottom and vary from
free sand to mud. Given the complexity of the factors that control the
hydro-sedimentary functioning of the Grand-Popo lagoon, it is recommended that
periodic hydrological and bathymetric monitoring be carried out to locate
exceptional variations in water levels to prevent not only the risks of
overflowing lagoon waters and the flooding that follows but also spectacular
erosion of the lagoon banks.