Sediment Dynamics and Shoreline Change Processes at the Niger Delta Barrier Island Coast

The barrier island coast of the Niger Delta is one of the most dynamically active and ecologically sensitive shorelines in Africa, experiencing accelerating erosion driven by wave energy, reduced fluvial sediment supply, and relative sea level rise. This study investigated sediment dynamics and shoreline change processes at four barrier island transects in Bayelsa and Delta States using a combination of field measurements and multi-temporal satellite imagery analysis. Shoreline change rates were computed from Landsat and Sentinel-2 imagery for the 2010 to 2024 period using digital shoreline analysis. Sediment transport rates were estimated from direct in-situ current-sediment flux measurements during spring tidal conditions. Sediment core analysis documented the stratigraphy and depositional history. Wave climate data from ERA5 reanalysis were used to compute longshore drift potential. All four study transects exhibited net erosion, with rates ranging from 2.1 to 9.8 metres per year. The highest erosion rates were associated with inlets where tidal scour prevented sediment recovery. Computed longshore drift demonstrated predominantly eastward sediment transport driven by south-southwesterly wave approach. Sediment budget analysis confirmed a deficit driven by reductions in fluvial sediment supply attributed to upstream reservoir trapping (Kainji and Shiroro dams) and subsidence from subsurface oil extraction. Sediment core analysis revealed a shallowing and coarsening-upward sequence indicative of progradational phases now replaced by retrogradational dynamics. The study presents the first integrated sediment budget analysis for this coastline and recommends engineered sediment bypass solutions and managed retreat planning. Keywords: sediment dynamics, barrier island, Niger Delta, shoreline change, sediment budget.