Deciphering Litho-Facies Heterogeneity and Sedimentological Variability in Tropical Tidal Flats of the Calabar and Great Kwa Rivers, Nigeria: Implications for Coastal Sediment Dynamics

Abstract

This research investigates litho-facies heterogeneity and sedimentological variability in the tidal flats of the Calabar and Great Kwa Rivers located in southeastern Nigeria. Systematic collection of seasonal sediment profiles was conducted across four tidal flats: Adiabo, Marina, Atu, and Idundu, followed by analysis through grain size statistics, sedimentary structure descriptions, and facies correlation techniques. Five primary lithofacies were identified: coarse sand, fine sand, silty sand, mud, and mixed facies. This classification indicates a complex depositional mosaic influenced by hydrodynamic energy gradients and variations in sediment supply. The sediment grain size ranged from medium to coarse sand at Adiabo (Calabar River) to very fine and silty sediments at Marina (Calabar River). Muddy sands characterized the Great Kwa River's Idundu flat, whereas Atu flat displayed medium to coarse sands. Litho-facies correlations indicated limited intra-river continuity while revealing significant inter-river similarities, particularly between Atu and Adiabo, and between Idundu and Marina tidal flats. Vertical fining-upward trends and lateral facies variability indicate dynamic depositional environments shaped by tidal currents, river discharge, and human activities, including dredging. This research addresses significant knowledge deficiencies in the sedimentology of West African tidal flats and highlights the necessity of integrating both natural and anthropogenic influences in the management of sedimentary environments. This highlights the importance of enhancing temporal monitoring, sediment transport modeling, and interdisciplinary methods to comprehend the ecological and geomorphological processes in tropical tidal flats, which face growing pressures from natural and human activities. These efforts are essential for the sustainable management of coastal systems in tropical regions.