Evaluation of Drainage system in Kebena stream catchment, Addis Ababa
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Date
2013-08
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Addis Ababa University
Abstract
This study has investigated the overall challenges of the urban drainage system in three sample Woredas (Woreda 6, 7 and 8) in Kebena Stream Catchment of Addis Ababa. These Woredas were selected because of the fact that they are the most flood prone areas and representative to address the objectives of this study.
Rapid expansion of built environment and poor urban drainage managements are the major problems in the study area. The objective of this research is to evaluate the existing storm water drainage system of Addis Ababa by selecting sample representative sample area. An exploratory and descriptive type of research methods were used to describe and explore the existing condition of the general urban drainage system and the natural water ways with the help of Ms-excel, AutoCAD and ArcGIS, HEC-GEOHMS, Google earth, Flow Master and the results have been presented with known statistical tools.
The result of this study shows that the major cause of flooding in the drained part of Addis Ababa is a changing flood regime due to mainly the expansion of built environment. Sample design flood calculation based on the guideline for three sample Wereda’s shows, in Woreda 6, of all the drains 17.74% of the drainages are capable of conveying safely the runoff in to the water ways. In woreda 7 out of the total drains only 29.75% of the drains have the capacity to convey the run off in to the stream. And also in woreda 8 out of the total drains only 16.5 % have the required capacity. Apart from significant flood regime change, field visits and survey reveals that there is inadequate integration between road and urban storm water drainage lines, luck of sustainable urban storm management, extraordinary challenge of damping solid and liquid waste water in the drainage system. Before, the urban drainage becomes a permanent socio-economic nuisance and brings irreversible damage to the city, this study strongly recommends immediate implementation of Best Management Practice (BMP) that is supported by strong institutional setup, policy framework, and the public at large.
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Stream catchment