Measuring Flow Velocity with Acoustic Doppler Current Profiler in the Commodore Channel Lagos, Nigeria: Implication for Understanding Channel Dynamics

Abstract

This study is conducted to investigate the flow characteristics in the Commodore channel. The Commodore channel is situated along the barrier bar complex of the Nigerian coastal zone. The dimension of the channel is 0.5 to 1 km wide and 10 km long. Numerous lagoons within the barrier bar complex connects the Atlantic Ocean through the Commodore channel. The construction of stone moles and dredging operation have significant impact on the stability and flow velocity and this has induced siltation and erosion problems at different sections of the channel and its adjacent beaches. In this study, we deployed the Teledyne RD instrument (1996 - 2010), Work-horse Sentinel Acoustic Doppler Current Profiler to measure water flow pattern along the Commodore channel. The equipment comprises of four beams transducer with transmitting frequency of 300 kHz. The ADCP was mounted on a boat and deployed with its transducer facing down to collect current velocity datasets along twenty transect lines covering the channel section. We processed and analysed the raw field data with Win-River and Matlab softwares to produce streamwise current velocities and depth average (DAV) profiles of selected transect lines representing the channel entrance, mid-stream and up-stream respectively. Our results shows variations in flow velocities within the different channel area. The streamwise flow velocities along the channel mouth was slightly higher than the velocities along the middle and upper reaches. Maximum flow velocity of 1.00 m/s were recorded within the channel centre while minimum flow velocity of 0.11 m/s usually occurred along the boundaries of each transect. This implied that the channel centre are areas of high energy associated with strong current while the channel banks are areas of low energy associated with weak current.

Publication Info:

Author: Rabiu, A.1 , Maigari, A.S.2, Adegbie, A.T.1 and Imhansoelevam, T.M.

Volume: 57

Issue: September

Published By: Journal of Mining and Geology, 2024-09-01