Impact of water overexploitation on highland lakes of eastern Ethiopia |
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| Authors: | Tamiru Alemayehu Wagari Furi Dagnachew Legesse |
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| Institution: | (1) Department of Earth Sciences, Addis Ababa University, P.O. Box 1176, Addis Ababa, Ethiopia;(2) Oromiya Water Well Drilling Enterprise, Addis Ababa, Ethiopia |
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| Abstract: | The eastern Ethiopian highland is endowed with large potential of water resources in terms of rainfall, groundwater and surface
water. Yet, due to overpumping of lake water and groundwater and environmental degradation, Lakes Haromaya and Adele have
completely dried up. The environmental degradation, due to deforestation and clearing of land for farming, has increased the
rate of siltation in the lakes that dramatically decreases the lakes’ volume and surface albedo, which increased the rate
of evaporation. The impact of these factors is aggravated due to decreasing net recharge to the lake and the alluvial aquifer.
Over the last 35 years, pumping of lake water for irrigation, mainly for subsistence farming, domestic and industrial use
shows an increasing trend. Hence, the available water for drinking and industrial purposes decreased drastically. In this
research, classical Penman aerodynamic combined energy budget, Penman nomogram methods, conventional soil moisture water balance
method and Penman–Monteith model were adopted to estimate free evaporation, actual and potential evapotranspirations. The
results indicate that evaporation is the dominant factor for the loss of water and water abstraction is 316% higher than the
effective precipitation, which is 110 mm/year. Therefore, overexploitation of the available resources has played an aggravating
role for the loss of the lakes in the area. The main cause for such resource depletion is the lack of integrated water resources
management strategies. The current water shortage in the area has mainly affected urban residents of Harar, Awoday and Alemaya
towns and the surrounding villages, which depend heavily on the two lakes. To alleviate the current crises interbasin water
transfer and rainwater harvesting would be possible alternatives besides ameliorating environmental situation of the basin. |
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| Keywords: | Groundwater Evaporation Surface water Water resources |
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