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2 Journal of Ecological Engineering

2 2016

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Formulating an Optimal Drainage Model for the Calabar Area Using Cartographic Techniques

Ugbong I. A., Budagov I. V.

Journal of Ecological Engineering

2016

Vol. 17, nr 1

1--9

In order to achieve the task of formulating an optimal drainage model for the Calabar area, the Calabar drainage system was studied using some cartographic techniques to analyze its surface run-off and channel characteristics so as to determine how floods are generated. A morphological analysis was done, using detailed contour maps prepared for the study area. The “Blue line” and “contour crenulations” methods were used to recreate the expected run-off channels or drainage networks under natural non-urbanized conditions. A drainage structure with 6 major basins and 73 sub-basins was discovered. Existing storm drains were constructed without regards to this natural structure and so floods were generated.

A Hydrophysical Analysis of Urban Surface Runoff, Channel Characteristics, and the Incidence of Flood and Erosion Over the Calabar Drainage Area, Nigeria.

Ugbong I. A., Budagov I. V.

Journal of Ecological Engineering

2016

Vol. 17, nr 3

30--40

Hydro-physical processes operating in the Calabar drainage area were analyzed by estimating the volume of surface runoff carried in each basin and sub-basin, using field measurements of flow velocities in conjunction with the “Rational Method” mathematical model proposed by civil and environmental engineers. It was found that run-off flow is affected by at least three factors which either produce floods or erosion conditions. The factors include size of catchment areas, gradient and lengths of flow channels. The Multiple Regression statistic was used to test these relationships. The results showed a strong statistical correlation among these variables, as well as between these variables and flow characteristics. It was found that for all the basins, runoff volume increased with increasing surface area of the catchment; just as areas with lower elevations register higher flow volume accompanied by flooding; with a reversed condition in higher ground where higher velocities are found with resultant erosion conditions. Also channels with considerable lengths receive higher flows along their courses downstream, and thus produce floods. It was therefore, recommended that in addition to the six major drainage channels recommended for the area, each channel and each segment of a channel should be determined by its gradient, drainage area, length of flow channel.