The aim of this work is to characterize the sedimentary hydrodynamics responsable for the morphological evolution of the beaches adjacent to the Assinie Passe. We opted a posteriori for a sedimentological approach based on granulometric analysis, for which fifty-four sand samples were taken from the three levels of the beach foreshores at varying depths, following four profiles of the two squares. These samples, subjected to physical and numerical processing, yielded graphs whose analysis reveals three granulometric stocks transported by rolling, graded suspension and saltation from coastal dunes and rivers. These predominanttly fine sandy facies are « well classified«, with acuity indices in the mesocurtic, platycurtic and rarely leptocurtic intervals. This approach shows that the beaches adjacent to the Passe of Assinie are governed by a relative sedimentary hydrodynamics, dominaded by the combination of marine currents (tide and swell) and the contribution of fluvial currents. Knowledge of the sedimentary hydrodynamics of beaches adjacent to river mouth is fundamental to the monitoring of coastal erosion and the sustainable management of the evoluting coastal environment.
The study is a contribution to the characterization of electro-facies and lithologic facies of fluvial systems in Ivorian Continental Terminal by analyzing gamma ray recordings and lithologic percentage data. The lithostratigraphy of the well was reconstructed using Strater software by a combined analysis of GR recordings and litho-granulometric data. The analyzes reveal nine litho-granulometric facies in this well and are mainly composed of coarse sands. These are medium clayey slity sands, coarse clayey slity sands, medium sands, coarse sands, medium gravelly sands, coarse gravelly sands, very coarse gravelly sands, gravels with coarse sands and kaolins. About the electro-facies, the analysis of log GR revealed 21 diagraphic facies (electro-facies) including 4 baselines, 5 lines of positive turns and 8 negative turns and 4 egg shapes. They have been identified in the lithologic facies. The deposit environment of BNC1 well formations is characterized by log shapes such as: cylindrical, funnel, bell and Serrated. These forms reflect fluvial environments such as braided channels and meandering channels (floodplain).
The objective of this study is to present the morphology of the bottom and to characterise the filling dynamics in the downstream sector of Buyo lake. A bathymetric survey carried out in March 2021 and the use of an old topographic map of the Buyo hydroelectric development dated 1980, allowed to apprehend the impact of the hydrosedimentary processes on the morphological evolution of the Buyo lake bottom. The analysis of the topo-bathymetric maps revealed that the downstream sector of Buyo Lake presents a rather irregular relief with depths ranging from 0 to 26 m. The greatest depths are located at the level of the flood spillway and the shallowest depths in the vicinity of the water intake. The 3D map of the lake shows the presence of depressions and shallows. The maximum depth was 24 m in 1982 and will be 26 m in 2021. In some places, the depressions of 4 and 22 m that were recorded in 1982 are 6 and 16 m respectively in 2021. The volume of deposition over the last 39 years (1982 to 2021) is estimated to be about 6,130,297.08 m³ of sediment with a filling rate of 68 cm/year. The analysis of the main channels revealed bathymetric profiles of intermediate and « V » morphology.
According to local nomenclature, there are four sub lagoons that represent the lagoon system of Grand-Lahou. The Tagba lagoon is the most important one because it is in contact with the sea through the mouth of Bandama river. The Morphology and the bathymetry constitute a challenge for local residents whose main activity is fishing. The present study aimed to update the bathymetry of the lagoon. The depths obtained are low, 3 m on average with maximum of 6 meters. The action of river currents and tidal current is responsible of the morphology of channels.