July-August 2025

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Sedimentological and Paleoenvironmental Assessment of Anthropogenic Impacts on Urban Lakes In Yamoussoukro (Côte D'ivoire), West Africa

Atto Yapi Désiré Sosthène Ronald, Kouadio Yao Peter Konan Guy Serge

ABSTRACT:The urban lakes of Yamoussoukro, situated in central Côte d’Ivoire, play a crucial ecological and hydrological role by regulating stormwater, mitigating floods, and enriching the urban landscape. However, rapid urban expansion and intense human activities on their watersheds have increased erosion and sediment deposition, threatening their long-term sustainability. This study aims to characterize sedimentation processes in Lakes 5 and 9 in order to assess the origin and dynamics of recent deposits. Twenty sediment samples were collected using a Van Veen grab and subjected to granulometric, morphoscopic, and mineralogical analyses. Three main lithological facies were identified: sands, muds, and mixed
sediments. The sands are predominantly coarse to medium (mean size: 630 μm) and poorly sorted, reflecting variable hydrodynamic conditions. Quartz grains, ranging from sub-angular to sub-rounded, indicate short-distance transport. Analysis of transport modes reveals a predominance of saltation (60% in Lake 5 and 51% in Lake 9), accompanied by bedload for coarser fractions. The mineralogical composition, dominated by quartz (74%), feldspar (20%), garnet (4%), and muscovite (1%), points to derivation from the local Paleoproterozoic basement. Overall, the results suggest that current sedimentation is mainly controlled by urban soil erosion and anthropogenic inputs. These findings highlight the urgent need
for integrated watershed management and erosion control strategies to maintain the ecological functionality and sustainability of Yamoussoukro’s urban lakes.

[ FULL TEXT PDF 1-14 ] DOI: 10.22587/ajbas.2025.19.4.1

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Origin Of Bitumen Seeps InThe Sedimentary Basin Of Côte D’ivoire – The Onshore Case

Assa Maxime ABBEY; Assoué Kouakou Sylvestre KOUADIO; Blandine Akissi EGORAN; Loukou Nicolas KOUAME

ABSTRACT:The Ivorian onshore sedimentary basin, which has several areas of bitumen seepage in Samo, Kodjoboué, and Eboinda, has yet to yield any discoveries of liquid or gaseous petroleum The study aims to understand the sources of bitumen observed on the surface or deep within the sediments. Scientific work by various authors, based on bitumen discoveries and technical studies by oil companies, has led to the discovery and production of oil in Cretaceous formations in the offshore part of the Ivorian Basin. The study reveals that mapping these seepages shows bitumen outcrops in Adiaké, Kodjoboué, Samo, and Eboinda within the sandy-clayey complex, as well as bitumen traces in oil wells at Port-Bouet-1, Bérou-1, and Eboinda-1. The satellite faults of the Lagunes fault are believed to be the migratory sources of oil from the reservoir depocenters of wells D1-1X and IVCO-3 offshore, toward the onshore sediments. These observations strengthen the geological and petroleum interest of the onshore area of the Ivorian basin and pave the way for further studies of its active petroleum system.

[ FULL TEXT PDF 15-25 ] DOI: 10.22587/ajbas.2025.19.4.2

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