ASSESSMENT OF GROUNDWATER HYDRAULICS, HYDRODYNAMICS AND SUSTAINABLE UTILIZATION THE CASE OF ADDIS ABABA CITY
Creators: name: DEBEBE MULETA WERDOFA
Publisher: name: National Academic Digital Repository of Ethiopia
Year: 2020
Subjects: Groundwater Dynamics, Hydraulic exploitable, sustainable utilization, depletion

description: Addis Ababa is a big city that demands large volume of water supply for domestic, commercial, industrial<br> and institutional use. In the past two decades, the city has been under continuous demand of<br> additional water supply source improvement due to critical shortage of supply particularly a serious<br> problem at the outskirts at topographically high places. In order to overcome the existing problem,<br> groundwater development optioned as emergency water supply project. However, the development<br> continued without giving attention to its sustainability and now takes about 63% of the share. Over the<br> last decade, many well-fields have been drilled; Akaki, Legedadi-Legetafo-Ayat, South-Ayat-North-Fanta,<br> and Addis Ababa pocket areas in the same watershed that have an area about 1490 square kilometer. The<br> main objective is to assess the groundwater hydraulic, hydrodynamics and sustainable utilization of the<br> sources. Hydraulic conductivity and transmissivity in the watershed vary from 0.02 to 256m/day and<br> 5.4x101 to 2.16x104m2/day respectively. The major aquifers are fractured &amp; scoriaceous basalt, scoria,<br> fractured ignimbrite or a combination of these materials. The estimated exploitable groundwater potential<br> and annual recharge are estimated to be 382.3MCM and 103MCM/year respectively. However, the annual<br> planned and current groundwater withdrawals from the well-fields by AAWSA are about 151 &amp;<br> 103MCM/year respectively but overall together with other users the planned and current production<br> increase to about 251 &amp; 153MCM/year respectively. The current estimated gap between withdrawal and<br> recharge is about 50MCM/year. The figure may increase to 134 MCM/year when ongoing projects of<br> AAWSA are completed. In general, the current utilization itself significantly deteriorated the annual<br> production volume of AAWSA from the planned/design 151 to 103MCM/year. Analysis of water level<br> contour for Akaki well-field indicated that 84.50 % of the current pumping water levels were below the<br> dynamic water level. The arithmetic mean analysis of measured pumping water levels of individual wells'<br> indicated that 81.4 % of water levels are below the dynamic water level. In particular, old Akaki wellfield has been severely depleted in which out of 24 drilled wells 13 of them are abandoned because water<br> level significantly declines. The production deteriorated from 40,000 to current 9,667meter cube per day<br> within the last 18 years. Despite huge importance of groundwater, it has been understood poorly and<br> undervalued. It is a finite resource and the aquifers can become depleted at this extraction rates which<br> exceed recharge rates. Therefore, groundwater management should be practiced through reliable aquifer<br> characterization, sustainable development, planning of conjunctive use of surface water and artificial recharge