Flooding Incidence and Drainage Network Analysis in Bonny Island, Nigeria | Chapter 09 | Emerging Issues in Science and Technology Vol. 2
The incidence of occasional flooding of
an estate, a tank farm in Bonny Island, Niger Delta was investigated. The study
was carried out to identify the remote causes of flooding and in turn proffer a
solution. Detail field investigation involved identification of thirty one road
side drains of rectangular cross-section; measurement of drains inverts (spot
heights) at selected locations yielded estimates of longitudinal slopes
(0.000416 – 0.0074 m/m), a case of very mild slopes. The invert profiles of 15
road side drains indicated a case of inconsistent slopes, a mix of positive and
negative slopes over short intervals, the observation accounts for siltation
and ponding in the drains. The redesigns of the existing drains were actualized
via the use of MODRAIN code, based on the principle of best hydraulic section
with input data options for rectangular or trapezoidal channels; constant or
variable bottom slopes and runoff coefficient(s). A comparison of the existing
and newly designed drains with respect to cross-sectional areas confirmed that
80% of the existing drains are oversized, in what is captioned “Bigger existing
drains”. Apparently, the issue of occasional flooding of the Estate cannot be
all blamed on inadequate drain size but on existing bottom slopes (very mild
slopes) of the drains.
Author(s) Details
Ify L. Nwaogazie
Department of Civil and
Environmental Engineering, University of Port Harcourt, Nigeria.
Levi O. Uba
Chattel Associates (Nig)
Limited, 14 Old Aba Road by Woji Junction, Port Harcourt, Nigeria.
Charles C. Dike
Department of Civil and
Environmental Engineering, University of Port Harcourt, Nigeria.
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