Groundwater Evaluationof the Wukro-Genfel Sub-Basin Tigray, Northern Ethiopia
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Date
2007-07
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Addis Ababa Universty
Abstract
The Wukro-genfel-sub-basin is found in Tigray Region at distance of 829 Km from
Addis Ababa. Geographically, it is located in 130 55’’ 00’N_130 42’’ 50’N and 390 31’’
00’E _390 40’’ 34’ E. The climate is classified as temperate (weinadega) with an altitude
of 1900-2700m m.a.s.l. and annual mean weighted rain fall and temperature of 584mm
and 18.8 c0 respectively. The annual Actual and potential evapotranspiration are also 546
mm and 1392mm respectively. The average annual recharge of the area is estimated
33.25 mm.
The area is dominated by Mekelle outlier sediments in the central and south and low
grade metamorphic rock in the north and east which are highly affected by faults and
lineaments. The characteristic aquifer of the area is fractured confined aquifer and
multilayered semi-confined aquifers. The hydraulic conductivity are variable with in very
short distances that indicates there is very weak hydraulic relation among the formations
laterally. The hydraulic conductivity of the area is higher in the central and southern part
that ranges from 3.14 m/d and 11.87m/d respectively.
The hydrochemical analysis showed that the dominant water type are both Mg-Ca- HCO3
and Ca-Mg-HCO3 that varies from site to site that indicates the formation is dominated
by Ca and Mg-carbonate rich minerals or rocks /such as limestone and dolomite rich
slates .But far to the southern part of the area where shale is dominating and also in Deep
well in the limestone areas Ca-Mg-SO4-Cl type water is observed. Therefore, the
hydrochemical is controlled more by geological formation than groundwater flow
interaction with rocks.
The water from wells in the limestone is very hard to bad class (2214 mg/l ) TDS and
also the salinity ranges from medium to very hazardous range for plant growth .
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Keywords
Wukro-Genfel-Sub-basin