Sediment Dynamics and Sedimentation Patterns as Veritable Tools for Assessment of Shoreline Erosion on Sandy Beaches
Article No : sgrj-v1-1001
Saviour P Udo-Akuaibit
Studies on sediment transport on tropical sandy beaches of the South-East coast of Nigeria were carried out to understand the dynamics and pattern of sedimentation at beaches adjoining Qua-Iboe River Estuary, Ibeno, Akwa Ibom State. The beaches are genetically characterised by very fine grained, well to very well sorted sediments. Results of shoreline mapping and beach profile surveys showed no significant relationship and correlation with the alongshore variations in grain size parameters and the erosion arcs/ areas on the beaches. Moreover, the backshore sedimentary facies were morphologically stable at the beaches due to less tidal inundation and the presence of scanty vegetation. Updrift beach revealed a stable upper foreshore and a trough-like mid-foreshore, starved in sediment and sheltered from direct and intense wave impacts by an elevated lower foreshore which morphologically developed into offshore sand bar. On the other hand, down drift beach depicted erosion at the backshore and upper foreshore while mid- and lower foreshore revealed accretion. However, eastward directed longshore sediment transports energized by oblique incident waves were evident at the updrift beach whereas cross-shore sediment transport systems controlled by shore parallel waves were prevalent at down drift beach. The beach morpho-dynamics correlated strongly with increase in tidal influence during the accelerated phase of neap-spring tidal cycle.
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