Morphological Characteristics of the Bonny and Cross River (Calabar) Estuaries in Nigeria: Implications for Navigation and Environmental Hazards - The Land/Ocean Interactions in the Coastal Zone of West and Central Africa - page 93

Fig. 8 Navigational chart of Calabar estuary showing several sandbars, sandbanks and other underwater obstructions (from British Admiralty
Nautical Chart 3433 2013 )

in the Calabar estuary (Fig. 8 ), the main navigable channel
is almost midstream just east of the Tom Shot bank. Depths
within the navigable channel are between 6 and 7 m. Even
within this channel, there are several sandbars (Fig. 8 ).
Apart from the underwater ridges and shoals, several ship
wrecks (some underwater), pose navigational hazards in the
Bonny and Cross River estuaries.

bank erosion therefore pose navigational and environmental
hazards to ships and vessels as well as berthing facilities.
In many cases, jetties have been washed away as result of
erosion,

leaving the landing jetties isolated from the

estuary.

Conclusion

Shoreline and Bank Erosion

The Bonny and Cross River estuaries are of huge economic
importance to the economy of Nigeria. The morphology and
accompanying oceanographic and fluvial interactions pose
hazards for navigation and hence have adverse impacts on
the socio-economic activities in Nigeria. Regular dredging
of the navigable channels involves high cost and negatively
impacts the health of the estuary. Continuous monitoring

Shoreline and bank erosion is very prevalent along the
banks of the estuaries. Erosion is due to high currents and
the construction of several jetties which are perpendicular
to the shoreline. These features, coupled with the high
currents, cause massive shoreline erosion. Shoreline and