Environmental Engineering Reference
In-Depth Information
mainly formed by the Cross River, but also receives waters
from the Calabar and other streams. The Rio del Rey creek
at the eastern end of the estuary marks the boundary
between Nigeria and Cameroon. The estuary is 10-12 m
broad at its mouth and maintains the same breadth for
about 30 km. The upper facies of the Calabar River has a
thickness of 8 m, while the lower facies is 10 m thick. The
grain size distribution reflects that the facies has medium
sands and negatively skewed sediments. Also, coarse
sands, poorly to moderately sorted, and leptokurtic sedi-
ments characterize the upper facies.
Qua Iboe River Estuary
Plate 1
Overview of an estuary in Nigeria's coast
The Qua Iboe River estuary is a meso-tidal estuary with a
N-S-trending estuary which opens into the Atlantic
Ocean. The deepest part of the channel lies within the
central portion and is 10 m deep (Plate
6
).
Although sandy beaches are known to develop in some
portions of the estuary, most of them are fringed with tidal
mudflats and oligotrophic mangrove swamp (Essien et al.
2003
). In the Qua Iboe River estuary, the upper facies has a
thickness of 5 m, while the lower facies is 10 m thick. Both
its upper and lower facies are characterized by moderately
sorted, negatively skewed sediments. Very fine-grained,
leptokurtic to very leptokurtic sediments typify its upper
Facies, and medium sands and mesokurtic sediments typify
its lower facies. Table
1
, provides the details of tidal current
velocities for the Qua Iboe River estuary and Calabar River.
Tidal current velocity for other estuaries is not readily
available.
the largest in the West African subregion and is approxi-
mately 25 km wide at the mouth and more than 440 km
long, with a tidal flushing of 1.83 billion cm
3
per day (E-
nyenihi
1991
) and tidal amplitude of 3 m (Asuquo et al.
1998
). It is the largest estuary along the Gulf of Guinea
(Enyenihi
1991
) covering an estimated area of 54,000 km
2
with about 74 % lying in Nigeria with the remaining 26 %
in Cameroon (Enyenihi
1991
). The estuary has a long
coastline with fringing mangrove and a characteristic
muddy bottom. Also, the estuary has no sandbar blockage
but only a moderate tidal range of 3 m at Calabar. The
beaches around the estuary are a potential attraction for
tourists and perform numerous functions ranging from
species abundance, research, and educational purposes to
the protection and stabilization of the coastline.
Calabar Estuary
Imo River Estuary
The Calabar River is a NE-SW-trending tidal river and a
major tributary of the Cross River which has the largest
estuary in West Africa (Plate
5
). The Calabar estuary is
The Imo River is located in southeastern Nigeria and flows
150 miles into the Atlantic Ocean. The estuaries of the Imo
Plate 2
Niger Delta landscape
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