Study of the hydrometric signature and implication of spring tide conditions in the wouri-nkam channel of the cameroon estuary

The upper channel of the Wouri-Nkam section of the Cameroon estuary is poorly studied due to the limited finance, difficulties in accessibility, lack of political interests and information about its crucial role in the welfare of the local population. This study assessed short term fluctuations of hydrometric parameters to characterize the hydro-ecological system of this channel. High-frequency sampling of water level, surface currents and water quality parameters (Temperature, Salinity, pH, dissolved oxygen etc) were conducted during two spring tide conditions (May 2019 and 2020). The results obtained after spatial and statistical analysis revealed that salinity displayed a horizontal gradient ranging from the Bridge to Bona’Anja, with the first zero salinity (0 PSU) around Bonalokan (7 km away from the Bridge). The hydro-ecological status revealed a hypoxia situation (Dissolved oxygen concentration less than 2mg/l) in May 2020. Also, the two boundaries of this channel exhibited different current directions with amplitudes of about 1.2 m/s in the Bridge (with bidirectional flow and more important small scale features) and 0.23m/s in Bona’Anja (unidirectional flow). Similarly, the tidal range losses about 74% of its amplitude as it travels from the Bridge to Bona’Anja (May 2020). The correlation coefficients (r=0.71) obtained between water level and water quality parameters (salinity, conductivity and Total Dissolved solutes (TDS) confirmed the synchronized evolution observed between them with a time lag of about 1hour.