Assessment Of Drainage Structures From Babalola Junction Down To Ayegun River Of Irare Estate, Oye Ekiti, Ekiti State, Nigeria

ABSTRACT

Globally, natural disasters are becoming places lately, and they are the results of

climate change due to natural forces. Some of these disasters like floods, earthquakes,

landslides and draught happen, resulting in loss of human lives and properties. Flood occurs

when two or more acres of dry land or two or more properties are inundated by water or

mudflow. In this study, the reconnaissance survey of the study area was carried out. The

topographical map of the area contributing runoff to the drainage structures of the study

area was identified through desktop analysis. Appropriate formula was used to estimate the

discharge and thus, calculate the required cross-section areas of drainage structure and

compared to the existing cross-section areas to find out whether they were adequate or not.

The structural designs of the new drains was carried out based on the results from the

hydraulic analysis using BS 8110 and BS 5400. The hydraulic analysis revealed that the

average existing cross-sectional area of the drains is 0.21111 2 as opposed to the required

cross-sectional area of 1.44m2

• This indicates that the line drains are not adequate to contain

surface runoff. Therefore, it is recommended that the existing drains and culverts be

demolished and reconstructed. The average cross-sectional areas at sections 1, 2 and 3 of

the drains should be redesigned to 2.25m2 . Concrete grade of25N/mm 2 should be used for

both culverts and drains. Also, high yield reinforcements ofY16@200mmC/c should be

used as main bar and Yl2@300mm C/c as distribution bar for culverts. High yield

reinforcements ofYl6@200mmC/c should be used as main bar and Yl0@300mmC/c as distribution bar for line drains.