Identification and Engineering Geological Studies of Small Hydropower Sites in Muger, Jemma and Waleka Sub-Basins (Central Ethiopia)
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Date
2005-07
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Addis Ababa Universty
Abstract
Electrical energy is becoming an essential conunodit; for the modern life. En:r; sector.
weather industry, technology, transportation, public utilities or the domestic life, is now
dependent on electrical power. The dependence on electrical power is becoming more and
more, which has resulted into increasing demand for it. Therefore, with the increasing demand
for power, the activities on smail hydropower projects is accelerated in recent times. The
small hydropower schemes are the appropriate solution to power demand as these require
small capital investment and can be completed in a very short period of time, with minimum
adverse environmental impacts.
The present study area is located in Abay drainage basin, in the central part of the country.
Muger, lemma, and Waleka drainage Sub-basins of Abay ha\'e been identified for the
present study. The main objective of the present study was to identify potential Small
Hydropower sites in the study area and to carry out ground verification with engineering
geological appraisal, at pre feasibility level, of SHP sites (Selected sites).
In total 36 potential SHP sites has been identified during the present study. Out of these 36
site s observed discharge data was available for only 18 sites. For 9 small hydropower (SHP)
potential sites, flOW-duration curve is prepared from observed daily discharge data. However,
for 9 other potential sites the observed discharge data has been projected from adjacent
gauged stations by percent area ratio method for those which demonstrate similar catchment
characteristic. Initial estimation of the power potential of 18 SHP sites has been computed for
75% dependable discharge and taking turbine efficiency to be 90% and efficiency of the
generator as 95%. Thus, the total power potential, as estinmted for 18 idcntified sitcs comes
out to be 5325 kW.
Thus, these 18 potential SHP sites can be ground verified and be taken up for detailed
Engineering Geological Appraisal. However, for the present study, with the limitation of
resources, time and financial constraints it was not possible to undertake ground verification
and detailed engineering geological appraisal of all 18 SHP sites. Therefore, a sincere effOit
has been made to cover 4 potential SHP site to undertake ground verification and detailed
engineering geological appraisal, at pre feasibility level. These sites were, Beresa, Chacha,(ill/" and R"bi (;,"n('1"O. Tillis. these !~ '.il sites \Vere gHllllld verilied le)r the availability of the
head, discilarg.; and til.; possible la)l'lll, FUriher, engineering ge,)logical appraisal of these
sites has been carried out. In additi"ti to this at all four l'ropos"d SHP site, eng"'ec'nng
geological mapping has been carried out.
For the present study, an attempt has been made to tentatively design the varIOUS SHP
components and select the turbine based on the power potential for the selected site.
Further, in the present study an attempt has been made to develop a GIS data base on small
hydropower. Tllis data base is prepared with an intention to provide all necessary information
on SHP a1 pre-feasibility level for the present study area and may serve the planners and
developers to haw some form of 'first hand information' on small hydropower potential in
the area. The GIS database on SHP may serve as a useful decision making tool for the
planners and developers, intending to develop slllall hydropower schemes in the present study
area.
Finally based on the results and finding of the present study, certain recommendations has
been made.
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Keywords
Muger, Jemma and Waleka Sub-Basins