Browsing by Author "Mohammed, Abdulshikur"

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    Environmental Analysis of a Hydrologic System the Case of Tinishu Akaki River, Western Addis Ababa, Ethiopia
    (Addis Ababa Universty, 2007-06) Mohammed, Abdulshikur; Asrat, Asfawossen (PhD)
    Water Quality analysis of the Tinishu Akaki River System has been carried out with the objective of identifying where and when the river’s pollution and its consequences are more pronounced. And to determine what factors and / or processes prevail and control the situation spatially and temporally. To do so primary data on conventional water quality parameters; dissolved oxygen (DO), ammonia (NH3), Nitrate (NO3), Nitrite (NO2), PH, temperature(To) and total dissolved solids (TDS) was generated. In this study, five water samples were collected and analysed to represent the 2007 moderate flow period, the three spatial domains of the river (i.e. up, mid, and down streams) and the date when industrial effluents discharge is minimal. Besides, secondary data on the same and other physiochemical parameters for the years 1997, 1999, 2000, 2002/03, 2003/04, 2005/06, were collected from EPA monitoring unit and available literatures. After that, the available primary and secondary data were segregated between the three spatial domains, Low, Moderate, and High flow seasons, and Peak and little or No Industrial effluents discharge patterns. Then, by taking dissolved oxygen (DO) depletion as important water quality indicator pollution along the river course and its consequences have been analysed using spread sheet program. Moreover the physicochemical factors such as altitude, atmospheric pressure, temperature, Stream flow velocity, Salinity (TDS), BOD5, NH3, PO4, …etc. were used to justify the variation in DO level in the River water column. The results of the analyses depict that the extent of pollution is more severe when industrial effluents load is high and the river’s flow is low. Moreover, the midstream spatial domain is found to exhibit the worest situation in terms of pollution and or DO depletion. Above all, the increase in the concentrations of potentially harmful substances; heavy metals (Fe, Mn and Cr), ammonia, hydrogen sulphide, sulphates and phosphates is found to be associated with the generally declining DO level in the down stream direction. So as to abate this problem of water pollution, TMDLs (Total Maximum Daily Loads) and WLAs (Waste Load Allocations) for oxygen demanding wastes of industrial point sources is suggested to be the most cost effective and applicable mechanism of abatement that can assure the attainment of in stream water quality standards. Key Words: Dissolved Oxygen depletion, Tinishu Akaki River, Conventional Water Quality parameters, Ethiopia