POTENTIAL ASSESSMENT OF MICRO HYDROPOWER FOR RURAL ELECTRIFICATION IN SOME SELECTED SITES OF GENALE-DAWA BASIN, ETHIOPIA

Abstract

Genale-Dawa Basin is the third largest basin in Ethiopia in its area coverage. It has a basin area of 172681 square kilometres. The study area is mainly limited to the northern part of the basin in which the highlands of Sidamo and Bale are included. This area gets relatively ample amount of annual rainfall as compared to other areas of the same basin. In the study 21 micro hydropower sites were identified. All of them are found in the aforementioned northern part because of the dependable annual flow as a result of adequate rainfall in the southeast. All of the identified sites except one are unguaged. Therefore the discharges of these sites were transferred from the nearby gauged rivers by area-ratio method. There are about 30 gauging stations· in the basin. However, only four of them have full data for the duration under consideration. In order to come up with reasonable result for water-related studies, a data of at least 15 to 20 years is needed. Stream flow data of 19 years were analysed during the study. Prior to transfer of discharges to the identified river sites, filling and extension of the missing data was carried out. The catchment areas of the identified sites were determined from topographic map of scale 1 :50,000. The gauged rivers which have comparable catchment area and which are found in similar natural features were used for the transfer of stream flow. Having finished the process of transfer of stream flow, the potential hydropower and energy of the identified river sites were estimated. Two methods were used for this computation. These were the flow duration curve and the monthly flow. The total annual power and energy output of all sites as estimated by FDC were found to be 49,248.86kW and 44.633GWh/year respectively. The computation carried out by using the monthly flow shows that the total potential power and energy output from all sites were 81,927.58kW and 59.807GWh/year