Urban Design

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Browsing Urban Design by Author "Assefa, Alazar (PhD)"

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    Green Infrastructure Retro-fitting to Protect Urban Streams from Non-point Source Pollutions
    (Addis Ababa University, 2020-11) Tsegaye, Emebet; Assefa, Alazar (PhD)
    Uncontrolled urbanization causes serious quality degradation of surface waters through covering natural land by impervious surfaces that greatly increases the volume and velocity of stormwater runoff as well as transportation of pollutants from point and non point sources. Therefore, sustainable water management is essential. This study focuses on non-point source pollutants having an objective of identifying Green Infrastructure retro fitting options to protect the stream water from these pollutants in the localized sub watershed around Egziabherab church in Bole sub city of Addis Ababa. Both primary and secondary data were consumed for this study. The secondary data include contour map and base map collected from Addis Ababa plan commission, rain fall data from National Meteorological Agency and other related literatures. The primary data were the land use/cover, street surfacing and stormwater sample directly collected from selected sites. Software such as GIS, spread sheet, ArchiCAD, AutoCAD, Scketchup and laboratory taste were used for analysis and designing purpose. The result indicates that Total Suspended Solids exceed the limit of the recommended standard. Applying permeable pavers on private plots, 21–33.3% of the stormwater runoff and 68–86% of Total Suspended Solids generated from the entire development can be reduced. Rainwater Harvesting from roofs of institutional plots can reduce 6.4–9% of the total runoff. 100% of Total Suspended Solids can be reduced by vegetated swale, rain garden and riparian buffer. Generally, green infrastructure retro-fitting should be an integral part of urban plan and design at all scale to reduce runoff volume and improve stream water quality.