Flood Assessment on Addis Ababa Light Rail Transit System (LRT) (Meshualekiya – Gotera)
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Date
2015-10
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Addis Ababa University
Abstract
Addis Ababa has a pronounced rainfall peak during the summer (July to August).Flooding is a major problem for Addis Ababa city roads. Therefore, the study was carried out to assess the flood risk on Meshualekiya-Gotera corridor due to rainfall intensities of for different years of return periods.
This research paper assesses flooding condition due to the integration of Roads and Light Rail Transit drainage Systems of Addis Ababa with the help of ArcGIS and EPA SWMM modeling software.
The urban rainfall-runoff modeling was done for 15 minutes of intensity from IDF curves of Addis Ababa observatory for return periods of 2, 5, 10, 25, 50 and 100 years. The peak discharge values from Modeling software EPA SWMM for inlet manholes compared with rational method (rational formula) and nearly the same result were found.
The result showed that some of the left side (From Meshualekiya to Gotera) of road drainage manholes encountered flooding. The flooding time ranges from 10 minutes to the maximum of 20 minutes. For 2, 5, 10, 25 and 50 years of return period, no any flooding encountered in the railway line. But when it checked extremely within 100 years of return period, flooding occured on the railway track system for durations of 10.2 minutes only in one manhole location. So, the drainage system networks of the road previously designed and implemented have sizing problems.
As a recommendation by making simulation, pipe diameters of 1.06meter and 1.22 meter were recommended to link each other for flooded manhole areas. For Manholes (MH-L-433, MH-L-439, MH-L-440, MH-L-440’) section double piping (2 pipes with diameter of 0.75 meter) is best applicable solution to avoid the flooding near that area.
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Keywords
Rational method, ARCGIS, EPA SWMM, Flood risk locations