Study of Waves and Currents During Monsoon Season in Bonny Estuary, Rivers State

The Bonny Estuary in Rivers State, South South Nigeria, represents one of the most strategically important maritime corridors in Nigeria, accommodating heavy tanker traffic from the Bonny LNG Terminal and extensive artisanal fishing activities. Monsoon-season wave and current conditions create significant navigation hazards and complicate offshore operational safety. This study characterises waves and currents in the Bonny Estuary during the June to September monsoon season of 2024 using a combination of moored instruments and field surveys. A bottom-mounted acoustic Doppler current profiler deployed at the estuary mouth records current speed, direction, and shear profiles throughout the study period. A directional waverider buoy measures significant wave height, peak period, and spectral wave energy at an offshore position. Tidal constituent analysis is conducted using T-TIDE harmonic analysis software, and residual currents are computed by subtracting the tidal component from the observed current records. Wave transformation between the offshore buoy and the shallow inner estuary is modelled using SWAN spectral wave model with locally digitised bathymetry. Ship draught records and pilot reports are consulted to contextualise the hydrodynamic conditions with navigation risk. Results are expected to document maximum spring tidal currents of 2.5 metres per second and episodic wave heights exceeding two metres near the estuary entrance during peak monsoon events. Findings support revision of vessel traffic management procedures by the Bonny Port Authority. Keywords: monsoon waves, Bonny Estuary, tidal currents, ADCP, navigation safety