Water Supply and Environmental Engineering

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Browsing Water Supply and Environmental Engineering by Subject "Akaki Phase II"

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    Assessment of reasons for Yield Decrease of Water Wells in Akaki Well Field based of Design, Construction and Operation
    (Addis Ababa University, 2022-03) Bethelhem, Kena; Mebruk, Mohammed (PhD)
    Groundwater is of paramount importance for the city of Addis Ababa and the majority of the groundwater supplied to the city comes from drilled wells in and around Akaki-Kality sub city. Even though numerous water wells are built over the years, the majority of the wells fell to provide anticipated design yield. The study mapped 70 wells found in Akaki Phase I, Akaki Phase II, Akaki Phase IIIA & Akaki Phase IIIB on ARCMAP to see the spatial distribution of wells and their performance over the years. From the map, some wells were observed to perform better than their neighboring wells and some wells were found to perform worse than the neighboring wells. Therefore the research engrossed in understanding the reason behind this phenomenon mainly by focusing on the design, construction, and operation of selected wells from all phases of Akaki well field. The selected 35 wells were grouped in accordance with their performance. Data from the well-completion report was organized and analyzed to identify the possible reason for the decrease in yield. Parameters used to compare the grouped wells were depth, elevation, screen arrangement, geologic medium, filter material used, construction process, year of construction, and the drilling contractor. The result showed bottom elevation of some better performing wells is deeper than those in a worse condition which means they are tapping water from a deeper aquifer. Another finding was 60% of the study wells have 30-50% of their casing screened. Some wells perform worse than their surrounding wells because their screened section is lower. For these wells, it can be suggested to increase the screen section in accordance with the water-bearing formation. From the analysis done using the Cooper Jacob method, it was found that the majority of the wells are developed within the radius of influence of one another meaning pumping water from one well is affecting the neighboring wells. Another finding of the research is the drawdown result from single and multiple well tests which showed 100% of the wells are being affected by the surrounding wells which supports the result obtained on the radius of influence of those same wells.
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    Groundwater Management Practice: The Case of Akaki Phase II Well Field
    (Addis Ababa University, 2020-01) Lidiya, Bekele; Mebruk, Mohammed (PhD)
    Water is a precious natural resource vital for life, national development and the environment. Groundwater resource supports many urban and rural area of Ethiopia. In Addis Ababa city the shortage of portable water has not yet been solved even if Addis Ababa Water and Sewerage Authority have implemented different mechanism to solve the city‘s problem. This research is conducted in Addis Ababa city at Akaki Phase II groundwater well field located in the south East of Addis. The well field is currently one of the main sources of water supply to Addis Ababa City. The objective of this study is to assess the groundwater management practices of the Akaki Phase II well field and the effect of abstraction of water without proper groundwater monitoring system in place. According to the analysis of the pump test through different methods, the transmissivity and storativity values obtained in this research have great variation from the study report of WWDSE. Among the 15 wells analyzed 10 have underestimated transmissivity whereas the 5 wells are expected to have overestimated transmissivity. The groundwater sources of the Akaki Phase II has wrong assumptions in the design phase since there is not given a major stress to the well drawdown loss by considering either the well efficiency or the effect of partial penetration to the well. From the questionnaire response gathered; the result clearly showed in Akaki Phase II well field that the groundwater monitoring practice is not regular, inconsistent, and focused only on limited visible parameters. If the current monitoring practices continues it will lead to the failure of the wells and unable to meet the objectives of the project.