RANSITIONAL GOVERNMENT OF ETHIOPIA
I
WATER RESOURCES DEVELOPMENT AUTHORITY
MEDIUM SCALE HYDROPOWER PLANTS
•7    PROJECT
I
BESHILO HYDROELECTRIC
RECONNAISSANCE STUDY
ADDIS ABABA
ETHIOPIA
AUGUST 1995In submitting this report, it is recognised that little success would have been possible without the valuable assistance received from members  of the Ministry  of Natural Resources Development and Environmental Protection, Ministry of Mines and Energy, Water Resources Development Authority and Ethiopian Electric Light and Power Authority.
** . • «*?
The Medium Scale Hydropower Project Office likes to express its heartfelt gratitude to the citizens  of Wegel Ten a, the administrator, the Municipality  and the clinic  staff for their invalueble assistance throughout the field investigations periods.
The Project Office wishes also to acknowledge the excellent cooporation of the secretarial and subordinate staff who greatly facilitated the preparation of this report
The project Office is also grateful for the assistance and cooperation received from members of various  other government agencies  and private organizations  from whom important information was gathered.
The survey work was difficult and at times dangerous, and the Office would like to extend its appreciation for the manner in which the surveyors applied themselves to the task.
i
I
i
/FOREWORD
i
The Ethiopian Government has  for long recognized that economic  progress  will depend principally an the development of the hydropower potential resources of the country. Presently the Government has  embarked upon the development of these resources  through proper planning so as  to provide urgently  needed electric  energy  for small - scale industry, to facilitate rural development as well as to raise the standards of living of (he whole population in al! of the regions of the country,
Ethiopia is endowed with abundant water resources distributed in many part of the country, However, it has  not made significant progress  tn the field of water resources  development during the past four decades, tn particular, the exploitation of hydropower potentials was not noticeably  successful even if it was  given top priority  as  a major field of national development- Leaving aside the causes of underdevelopment, it is now strongly believed that this can be achieved through the implementation of a large number of hydro projects in the most divers  and varied terrains  of the country. Further, Ethiopia does  not yet posses indegenous  hydrocarbon resources, the hydro-energy  potential on the country  will continue to be a cheap source of power, renewable and pullution free energy  up to the forescable future.
In Ethiopia, as  in many  other developing countries, development of any  activity  have been concentrated primarily  in ihe central urban or more accessible areas, where the greatest number of people were seen to be served wuh minimum efforts  and economic  costs. However, by  far the largest percentage of the population in Ethiopia lives  in rural areas. Because these peoples are more spread, and mostly reside and work in areas that are more difficult to reach, they are less vocal than their urban counterparts. As the rural people have less disposable incomes, they have therefore been, for a long time, deprived of the relatively improved benefits available to those in the urban areas.In 1993. the population of Ethiopia was  plated at 52 million with in estimated high annual growlh rate of about 3%. This  is  another major point of nmocm that needs  to be looked into seriously  and immediately  in terms  of energy  supply  Ttquircmcnls  for service and broad productive activities.
The major electric  power planning and market survey  study  conducted so far bad forecasted paws  and energy  demand and supply  to the year 2040. A 1993 forecast predicted the possibility of both power and energy shortages being very acute starting, from 1995.
The existing power generation in Ethiopia and the projected energy  requirements  from the year 1990 ihruugh 2040 indicate and prove that the power generation needs to be increased by 4 timet by the year 2000, tnire than 14 times by 2020 and about 25 times by 2040.
The above hard facts, therefore, evidently  lead to an energy  development program fix accelerating the development process, notably  in foe undertaking of studies  and preparations of detailed engineering designs  of hydropower projects  that could be implemented within foe Shortest passible times.
To overcome (he deficiency in clothe power supply, in Ethiopia, special attention has therefore been given by  the Government to Medium Scale Hydropower Development (MSHD) in foe range Of 40 MW to 60 MW tapacites  rather than large Scale Hydropower Development Schemes  (LSI IDS). Experience has  shown that the liner require huge invesinjents, lengthy processes  for securing finances  as  well as  longer construction periods  which might consequently  not meet and fulfill foc targeted demands  for electricity  in the different regions at foe country  within foe shortest possible rime. With this  set goal for surmounting foe atcute shortage in hydroelectric  energy  in Ethiopia, foe Government has  gjvoi top priority  to foe development of a number of favourably  Ind fairly  distributed hydropower resources  at this critical stage of time
iiThe  rapid  development  of  these  schemes  will  definitely  promote  and  speed  up  regional  and national developments at different and strategic river basins which is one of the Government's program  for  harnessing  the  immense  water  resources  potential  of  the  major  river  basins  of Ethiopia.
Necessarily, the implementation of the Medium Scale Hydropower Development (MSHD) program will have to proceed from reconnaissance investigations of a number of selected river basins. These will then need to be followed by  pre'feasibility  and feasibility  studies  that will lead to complete engineering designs for direct use in construction works.
Henceforth, the required reconnaissance report has been prepared for one potentially rich river basin in the north of Ethiopia, namely the Blue Nile River. The Blue Nile River starts at t -aVr Tana and flows  initially  in an easterly  direction and gradually  turns  in a westerly  direction towards Sudan The Beshilo River Joins the Blue Nik river from a south west direction. This river has  a number of tributaries  of its  own. all of which flows  in deep gorge below the plateau area. The Beshilo river sub-basin is  within Region 3. In partially  alleviating the existing and impending electric  energy  shortages  in the national grid the totally  untapped hydropower resources in the Beshilo River are definitely seen to have huge potentials within the specific area of the MSHD program
The  report  finally  concludes  with  findings  and  recommendations  for  all  the  potential  sites namely Abbay 20 (AB 20). Abbay 21 (AB21) and Abbay 22 (AB 22).
ivTable of Contents
List of figures
List of photos
1.         ItfHmjCTION
I -1     Genera I
1.2     Background
I.           J           Purpose and scope of the Study 
2.         DESCRIPTION    OF PROJECT AREA
2-1     Location
2.2       Access 
2.3       Topography 
2.4       Climatic condition
2,4*1   Areal rainfall
2.4.2    Temperature
2.4.3    Evaporation A Evapotranspiration 2.4.4    Humidity 
2.5       Geology 
2.5.1    Background
2.5.2    Methodology 
2.5.3    Regional geo Logy 
2.5.4    Surface geology 
2.5\4. l             Geomorphology 2.5*4.2             Tectonics 
2.5.4.3             Slop Analysis 2.5.4.4             Soil Studies 
2.5.5    Seismology 
2.5.6    Ground water studies 2.$.7 Geology of dam sites 
2.5.7.1             Deffer village           dam  site    Abbay-20 2.5.7.2         Gulya village, dam site Abbay-2t
2.5.7.3             Day* village,       dam  sit* Abbay-22 2-6      Hydrology"
2.6.1    Genera]
2.6.2    Availability of river flow data
2.6.3    tong term river flow series
generation
2h6.4      Availability      and      dependability      of
me
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g S & 9
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It [1
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annual flow series 
20
2.6.5
Results of Analysis 
21
2.6.6
Flood estimation
23
2.6.7
Daily flow duration
curve
24
2.6.8
Sediment estimation
25
iDESCRIPTION OF DEVELOPMENT A ALTERNATIVE LAYOUT
3.1       Study execution
3>2*   Deve J opaen t concept
3,3 Extent of development
3-4 Alternative layout
3.4 d Scheoe one site Abbay-20
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28
32
33
33
3.4.1.1
Dam cite
33
3-4.1.2
Headrace
34
3.4.1.3
Penstock
35
3,4.|.4
Powerhouse
35
3.4.1.3
Reservoir
35
3.4.1.6
Construction materiat
36
3-4.1,7
Estimated power potential
36
3.4.2Sche«w two  Site Abbay-2|
3.4,2.1             Dam site
3.4.2.2             Headrace
3.4.2.3             Penstock
3,4.2.4             Powerhouse
3.4.2.5             Reservoir
3.4.2.6             Construction material
3.4.2.7            Estimated power potential 3.4.3 SchemG three site Abbay-22
3.4.3. 1            Dart site
3.4.3.2             Headrace
3.4.3.3             Penstock
3.4.3.■*          E’owerhousc
3.4.3.5          Reservoir
3.4.3.fi          Construction material
3.4.3.7          Estimated power potential POWER SYSTEM STUDIES
4.1       Background
4.1.1 EELPA s interconnected system
B
4,1.2 Supply dcoand balance in the ICS
4.2 Power & Energy Capability of the project
4.3 Mechanical equipments and services
4.3.1 General
4.3.2 Mechanical       equipments
4.3.2.J           Turbines
4.3.2.2          Turbine Inlet Valves 4.3.2.3          Discharge pit gate 4.3.2,4          Powerhouse crane 4.3.2.5          Mechanical services
4.4 Electric equipneni
4.4.1 Generator
4,4.2 Main power Transformer
4.4.3 Station service power
4.4.4 Transmission line
4,4,5 DC control         power supply
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SO
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ii4.4.6   Grounding system
4.4.7   Lighting
4.4.8    Control panel
4.5     Transmission system analysis 
4.5.1   Transnission system planning principles 
4.5.1.1            Genera! principles 4.5.1.2            Criteria
4.5.1.3            Approach
4.5.2    Result of the load   flow analysis 
5. INITIAL ENVIRONMENTAL ASSESSMENT
5.1       Background
5.1.1    Purpose and objectives of the study 5.1.2    scope
5.1.3   Contents   of report
5.2       Description of       the proposed          project 5.2.1   Abbay-20
5.2.2    Abbay-21
5.2.3    Abbay-22
5.3       Description of       existing environment 5.3.1    forest resources 
5.3.2   wildlife
$.3.3 Aquatic resources 
5.3.4    Archaeological, religious and historical sites 
5.3.5    Public health
«
5.4 Assessment of potential environmental impacts 
5.4.1    Positive Environmental Impacts 
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5.4.1.1
Electricity generation
76
5.4.1.2
Flood protection
76
$.4.1.3
Employment
77
5.4.1.4
Wildlife and birds 
77
5.4.1.5
Other benefits 
77
5.4.2 Potential negative environmental
impacts
5.4.2.1
Social impacts 
7$
5.4.2.2
Loss of    agricultural
land
79
5.4.2.3
Loss of    gazing land
79
5.4.2.4
Effects     on forests 
79
5.4.2.5
Effects     on vegetation and
wildlife
SO
5.4.2.6
Effects on aquatic resources 
30
5.4.2.7
Impact on public health
8l
5.5       Evaluation of project
82
5.5.1     Comparative
evaluation matrix 
82
5.5.3    Conclusions 
86
ill6. SOCIO - ECONOMIC ASSESSMENT
6.1 Background
6-2 Methodology
6.3       Administrative Division
6.4       Land Holding System in We. lie
6.5       Demographic Data
6.6      Women Deve lopmen t
6.7       Social nnd Economic Aspect of the
proposed Dm sites
6.7.1 Abbay - 20
6.7.1.1            Location and Descript ion 6.7.1.2            Economic Activity
6.7.1.3            Health
6-7.1.4            Education
6.7.1.5            Comaunicat ion
6.7.1.6            Ethnic group language and religions
6,7.2 Abbey - 21
6,7.2.1            Location and Description 6-7.2.2            Economic Activity
6-7.2*3           Health
6.7,2.4            Educt ion
6.7.2.S            Communication
6.7,2.6            Ethnic group language and
re Ligions 6.7.3 Abbay - 22
87 87 80
88
89 97 99
99 100
LOO LOO
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101 sot 102
102
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103
103
103
103
6.7.3.1
Location and Description
6,7.3-2
Economic Activity
6.7,3.3
Health
6.7.3.4
Eduction
6.7.3.5
Conaunicat ion
104
IQ4
104
105
105
6.7-3-6            Ethnic group IsngUAge and
religions
6.6 Impacts and Effects of the Proposed Projets
6.8.1    Short term, impacts
6.8.2    Long term impacts
7. COST ESTIMATES
7.1       Basis of cost estivate
IOS
105
106
106
109
109
7.2       Cost Estiaate
no
SITE RATING A C50NSTKUCT1W SCHEDULE
113
8,1 Project Evaluation
113
S.1.1 Geotechnica L
113
8.1.2 Environmental
114
8.2 Dcvelopment Comparison Based
on Capacity and Energy
114
8,3 Development Comparison Rased
on Generation and Project cost
115
3.4 Overall Site Rating
8.5 Construction Schedule
113
116
iv9. CONCLUSION AND RECOIWNDATI ON
9-1     Conclusion
9.2      Recommendation
9-2-1 Topographic Items 
9.2. ^Geological and Gcothencical Items 9.2.3    Hydrological Items 9.2.4    Environmental (EIA) iteas 
mores FIGURES ANNEXES
jj? n? jjg
119
120
122
12J
Annex-1         EVaLS output for Abbay-20
An jinx-2          EVALS output for Abbay-21
Anncx-J           Evals output for Abbay-22
Annex-4            Load flow analysis sumery ANNEX-5        Hydrological dale.
ANNEX-6        Composition of the Study Ted* ANMDt-7         Project Ter*s of Rcference(TOR)
vintroduction
1.1      General
Ethiopia iliilWl made significant progress m tflC field of water resources developmcnt during the past four decides. In particular, the exploitation of hydro power potential was not noticeably Successful.
Undei the Government's Eniergcncy Pro^ranzme, in alleviate the current shortage in poweF demand, priority uts have been identified in Abbay River Basin nan&sly AR- 20 AfJ-21 and AB-22 for subsequent studies  inorder to exploit their hydropower potential.
The sites were selected as priority implementable project emanated from desk review of previous studies by Water and Power Consultancy Services (India) Ltd- (WAPCO) experts  during the preparation of the preliminary  Waient Resources  Master Plan of Elhicpia in l$M.
For the objective of (he Reconnainanw Study sec TOR. ( Annex 7 )
1.2       Background
Inipite of its immense hydropower resources, Ethiopia has one of the lowest levels of per capita electrical Consumption m the world. Out qf hydropower petemill of about
15,000 - 30,000 MW, only about 370 MW (i.c less than 1%) has been exploited by 1995. Presently. marc than 90% of energy consumed in (he country is derived from biomass  fuels,  and  is  almost  entirely  used  for  cooking.  The  use  of  these  fuels  has resulted  in  massive  dcfoteslatiQ<n  and  subsequently  soil  erosion.  About  10%  of  the electric energy consumed in the entire country is generated by diesel fitel engines thus draining the meagre foreign exchange of Ethiopia-The special service agreement made (between the International Cooperation Administration - predecessor agency of LfSAlD ■ and the Bureau of Reclamation, U.S Department of Interior) for the provision of technical assistance to Ethiopia for conducting studies  of the natural resources  had resulted Ln identifying B number of irrigation and hydropower projects for various sub-basins in the Blue NO* River Basin as shown in Fig. 2, The report submined on this indicates that detailed sujvcy work could not then be carried out in this  basin due to the vastness, rugged terrain and inaccessibility of the area. The Bcshilo River Sub-basin was also reported to be one of the sub-basins  where the required level of investigation and study  had no: been carried out due to the above bard facts. Nevertheless, two hydropower potential sites (other than WAPCOS) were identified and was  reported that 25% of the potential could be economically dcveloped.
Freliminary site investigation Conduct by WAPCO have confirmed that there are 132 potential hydropower projects  within the Abbay  River Basin, The developable potential of these proposed projects is 112,220 GWWyr whilst the technical potential is 73,820 GWh/yr,
The promising plant sites for Medium Scale Hydropower Development Scheme within the same Basin, in the range of 40MW - 60MW, are 18 in number. From these
potential sites three sites have been selected and further investigated within the Medium Scale Hydroppowtr Plants Development (MSHPD) programme to select and recommend one or two hydropower plants for immediate implementation.
The candidate sites  for the development of Medium Scale Hydropower Development schemes  in the Abbay  Basin are three in number. These throe potential sites  were inspected and investigated to lhe level refined for reconnaissance study. Based on the outcome of the studies, the sites were put in priority order for subsequent detailed pre feasibility and feasibility studies and design that could eventually clear ways for one of these sites for immediate implementation.
2The site conditions  and other relevant detailed information together with the full results of the reccmnaissince study are described and presented tn the subsequent chapters of this report
IJ Purpose and Scope of the reconnaissauce Study
The purpose of theis  study  has  been to provide in general terms  a review and observation on the suitability and adequacy of lhe potentially attrativc medium scale hydropower schemes  on the basis  of previous  studies, data collected frinn field investigation, on actual site conditions and investigations.
This  reconnaissance report describes, asscscscs  and analyses  the three available hydropower potential sites and prioritises after testing all possible apparent alternative solutions. The report also indicates whether the potential projects appear technically, economically and environmental feasible. The report discusses on whether to proceed with further studies and investigations on lhe basis of collected data.
The economic, social and environmental issues expected io receive serious attention in Later studies are also identified but firm solutions are not developed in detail in this phase.
The findings of the reconnaissance study and firm recommendation for further derailed investigation; are presented after all conditions  and relevant informations  pertaining to hydropower development have been fully covered.
32.          DESCRIPTION OF PROJECT AREA
2,1      Localion
A
The Beshib project anta u bated ™  the plateau of w«lcm highlands, The plateau is  at a relatively  high elevation. The Blue Nile river starts  at Lake Tana and flows initially  ui an easterly  direction and gradually  turns  in a westerly  dimtioD toward Sudan. The Beslifa river joins the Blue Nile river ffean a south west direction. This nver has a number of tributaries of its nun, all of which flow in deep gorge below the plateau (See photo no. I).
The Beshilft river sub-basin comprises different alternative dam sites that are proposed by  the W AT COS studio. The sub'basin lies  between Longitude 38D 30'E and 39’IOT, and 11” !5' N and !1“ 30' N latitude. Lt is  bounded approximately  by D«sie into South Eastern, Wegcl Tetia to North East and biefas  Mcwdu (0 Nffrttl West (see figure No. i J.
The proposed potential sites have the fallowing locations.-
DAM SITES
LATITUDE (N) LO
NGITUDE (E)
Abbay-20
Abbay-21
Abbay-22
11’2423"
tilnr
ll°25’35"
39*O2‘1S"
38D 5337*
3Sfl 42'3«"
2,2 Access
The Bwhilo subbasin !; more w lew accessible upto to Wegwl Tena. The sub-basin hw over 4G! km all weather roads 1o Dessie town and a 98 km dry weather roads that leads tn Wegd
4Tcna. AU the trails and can track access ends before they reach the proposed dam sites. Part of the project sites  could be reached by  four wheel drive vehicles. The existing access between Dcssie to Wegel Tens needs to be looked and rehabilitated to an acceptable standard (Sec photo 2).
Site Abbay-20 u located between Tcnta and Defer villages. The nearest vitLagc far site Abbay-2i is  Gulya. The access  to this  site is  out of soviet (see photo No. 3), Site Abbay-22 is also located very near to the Jiw Btshilo junction. The road to Daya, the nearest village to the darn, is also out of function at the moment (sec Photo No, 4).
There  is  no  any  access  to  the  potential  ppwcibouse  location  in  the  Ucshilo  Gorge. Figure 3 shows the possible access profile to each dam site based on the IzlSO.OOT
23 Topography
The prominent feature of the project area are the high plateau which will impound the reservoirs, Following information on the regional topography  have been abstracted from the National Adas  of Ethiopia, published by  Ethiopian Mapping Authority  in 1988.
Ethiopia is a country of great geographical diversity with high and nigged mountains, fial topped plateaus, deep gorges, incised river valleys  and rolling plains. Over the ages, erosion, volcanic eruptions, tectonic movements and subsidence have occurred ar.d continued through mclania to accentuate the unevenness of the surface. Since th c country is located within the tropics, the physical conditions and variations in altitude have resulted in a grcaL diversity of climate, soil and vegetation.
3The Wcgel Tcna village is  in the western highlands  which are massive with an average height of 2,000 to 2,500m. The highlands  include many  sub-divisions  or blocks  separated by  the deep, steep-sided valleys  of the major rivers. The North Central Massifs including Gonder, Gojam and part of Wclo generally have a rugged surface with high elevation.
2.4      Climatic Conditions
The climate of Ethiopia is determined by the movements of the equatorial rain bells and the northern subtropical high pressure zone. Following the sun, the rain belts moves north and south in annual cycle across the equator, with a lag behind the suns position of 4 to 6 weeks. In July the axis of the rain belts lies directly over Ethiopia between 5* and 10°.
2.4.1     Aerial Rainfall
The area is characterized by one rainfall regime with unrmodal rainfall patient. The rainy months extend from May to September having very high concentration of rainfall in the months of July to August
The  mean  annual  rainfall  of  the  catchments  is  expected  to  be  about 900mm. The basin is moist sub-humid.
The  major  rainfall  period  July  to  August  experiences  high  flow  and then followed by periods of lean flow prevailing quite long period of2,4.2   Xempcralurt
The  temperatures  of  warmcsl  month  and  coldest  month  in  the  study area could be in the range of 20-24*c and 16-20*0 respectively.
i
2.43 Evaporation and Potential Evapotranspiration
It has been attempted co estimate pan evaporation using an approximate relationship of altitude and pan evaporations  which were recorded at the different mdeorologicai stations.
The   pan   evaporation   obtained   by   the   above   relationship   is   then converted  to  open  water  evaporation  which  could  be  indicative  value for considering evaporation losses from reservoirs and the surroundings. The rate of open water evaporation can be considered, at this level of the     study,     to     it     approximately     approaches     the     potential evapotranspiration and the estimated value of open water evaporation from  (he  reservoirs.  The  potential  evapotranspiration  is  taken  to  be about  ItilOmm.  This  should  be  dealt  in  detail  and  comprehensively studied in rhe subsequent phase of the study.
2.4.4   Humidity
f
The relative humidity of (he project area on the average condition can be taken to be about 65% transposed from the Komboicha station.
72.5 gEOLOGY
2.5.1    Background
The objective of this  studies  is  to discuss  the potential problems  that would be taken into consideration during the design and construction stages and to recommend further essential g<x> technical investigations few the next phases of study.
:i
During the field work  a brief survey  was  made on rhe general occurrence of the geology and surface expressions of the rock units, as observed on aerial photographs. Rock samples were obtained from dam sites and reservoir area.
2.5.2    Methodology
The present work  is  based on die WAPCOS report which was submitted to Ethiopian Valleys  Development Studies  Authority  on Waler resources Development Master Plan for Ethiopia.
In the present study possible access, major rock units, linear features (faults), and stream channels  were traced from aerial photograph interpretation using stereoscopes.
The basalt which usually lying in between and above the tuff and ash is  un-nuppablc  at the scale of the available topographic  maps. However, they  arc  indicated in the geological maps  using the help of ordinary camera pictures and aerial photographs.
8During the reconnaissance site investigation, the geological features were investigated and the reservoir area was mapped using I'50. 000 wale topographic  maps, which were enlarged tram l;Z5D,0<HJ  scale topo sheets.
1
The data synthesized from the collected rock samples and other gco- technical information collected from the site, is  being organized into this final report.
if
2.5J Regional Geology
The Beshilo river sub-basin is uniformly covered by basic tuff, ash and numerous  intercalated basaltic  layers, This  fact, which was  described in Meria (1973), is  confirmed by  field reconnaissance investigation in this  study. According to Meria (1973), these basic  tuff and basalt arc middle to lace Oligoccne age.
2.5,4   Surface Geology
2.5.4,1             (Geomorphology
Beshilo is a meandering river found in a deep gorge, surrounded with sharp cliffs  and escarpments. This  topography  is  formed mainly because of the presence of the basalt as a belt within the ash and tuff (Pltoto 5 shows belts of basalt layers within the ash and tufi), Had the basalt been absent the topography could be characterized by low relief or flat plains.The tip of (he reservoir of the dim (dam Abbay-20) exlcnd upstream uplo the Wtgel Tcni'Dcssic  road, within sharply  dissected hilts  in the north centra] massifs  of Wello. Photo 6 shows  the Bnhtlo river gorge within dissected hills. The mean slope of the Bcshilo river between Abbay-20 and Abbay-22 is about Smts'km
2.5.42 Tectonic*
The Beshilo river sub-basin is  some 100 kms  from the main Ethiopian Rift. No regional faults  art indicated within the basin in lhe geological map of Ethiopia, except the N-S trending faults al the rift boundary.
2.5,43              Slope Analysis
The genera) stope in lhe reservoir areas  of the dams  vary between 25* (the most gende) io 45* (sec  Photo qo.7). This very  steep slope with jointed and friable rock  mass  is potentially unstable, especially if water waves arc generated by either wind blowing across  the reservoir, or by  some exceprional incidents like earthquakes.
First of all, weathered basalt, ash and tuff arc all unstable when saturated, and the presence of the ash and raff on the lower slopes all over the reservoir basins cause* loss of support to the upper mass ( see Photo no. 8). Hence, the expected degree of hazard and risk  for land slide is  very  high as  the volume of material involved is tremendous.
1025,4.4                goUSjudlea
As mentioned  above,  the slope of the surface in  all the reservoir area is quite steep,  which  enhances erosion.  The rate of erosion,  tn  ific area,  is much  faster than  the rale of rock  decay. Because of this fact the material from the weathered  basalt and tuff is easily washed for no trace of soil is developed.
A thin  Layer of alluvial soil recently  deposited  above the sand and  gravel at some places along  the river bed  is being  used  to grow oops and vegetables by the local people.
2.5.5    Seismology
All the dam sites and  their reservoir areas are encornpassed  within  zone 2  in the seismic risk  map  of Ethiopia (see Fig.  4).  This zone is considered  as having a moderate risk of damaging earthquakes.
2.5,6    Ground Water Studies
Almost  all  streams  are  dry  most  of  the  time  in  the  year,  A  serious  shortage  of surface and subsurface water cause? drought in the region.
Although  no  bore holes am drilled  at this stage of the study,  it is clear that the ground  water table and  the piezometric levels are at a much lower level than  the expected  water level of the reservoirs.  This can cause a serious loss of water from the reservoir basins at the initial
stage. 
1
112.5.7    Geology of Dam Site*
2-5-7J     Defer VHuge (Dam Sitr ABBAY-20]
A- Lithology
The dam site (Abbay-20) and  the reservoir area are covered  by  a thick succession  of basalt,  basic tuff and  ash  (see Fig.  5),  The geological cross section  across the dam axis shows that the outcropping  lithologist arc repealing themselves as the valley gets deeper (see Fig. Q
AJ Basalt
The basalt,  which  stands as a competent layer within  the ash  and  tuff, is quite weathered  itself and  can  never be used  for concrete aggregates. Photo  No.  9  shows an  example of strongly  weathered  basalt.  Numerous fractures and columnar joints are common in this unit
A2 Ash and Tun
The ash  occurs irregularly  between  the tuff and  basaltie layers ( see Photo  No.  10).  The tuff occurring  inseparably  with  the ash  is very 
friable and  covers most of the reservoir area (see Photo  no,  11). Although  the tuff looks pumiceons al places,  it ls impervious enough to  be used  as a fill for an  earth  dam Photo  No.  10.  shows intercalated basalt, ash and tuff.
128. Structure
Two  major  faults  are  encountered  very  near  to  the  dam  site,  These fault* are designated a* fauk-A and fault’B (see Fig No. 5),
HI Faults
As is shown  in  the geological map  and  on  the photograph  this fault runs across the reservoir,  t.e.  parallel to  the dam axis (see Fig.  5  and Photo  No.  12).  The fault can  be very  deep  and  may  consist of a wide alteration zone.
BJ Fault-B
Fauh-B is situated  at a much  higher elevation  than  fault-A (see Figure No,  5).  It is not as deep  as fauIt-A.  however it can  be a cause of possible reservoir leakage Ln course of time.
BJ Joints
Whenever the basaltic layers are outcropping,  columnar joints art common.  The associated  penucabLlity  is a problem for the water tightness of the reservoir basin.
13
1
I
IC Cpn>trp<ftlDn Mi ttrill*
CJ RockQuirrici
There is a fairly  good  reserve of basalt (Photo.  14,15,  and  16) for quarry  development al about 6  kms irom dam site Abb*y-20.  This basalt which  is slightly  weathered  surfacially  extendi for about 14  kms upstream.
Cl River Ikd Deposit!
There is a tremendous amount of bauldcn,  cobbles,  pebbles,  and  gravel (sec Photo  No.  17) for concrete works (after crushing) and  fix  rolled fill darns.
Similarly a huge reserve of sand (see Photo No. 18) is available all aver the stream channel ( sec Fig No.5).
2.S.71 Gulya Village (Dam Site ABBAY11)
A,        Lithology
The dam site Abbay-2l and  its reservoir basin  are covered  with identical rock  types (sec Fig  No.7) that is weathered  basalt,  ash  and tuff like Abbay  ■ 20.  The geological cross section  ($w Fig  No.  8) at the dam site shows that the intercalated  basalt with  the ash  and  tuff is repeating itself.
148. Structure
A major fault runs parallel to  the clam axis down  stream of the dam (see Fie No.  7)- This fault is only  500  mu  far from the dam and  it can cause piping imjcr the foundation.
C. Construction Materials
C.l Rock Quarries
No  possible  site  for  a  met  quarry  ts  found  in  the  vicinity  of  the  dam site and reservoir area,
C.l River bed Deposits
Boulders,  Cobbles,  pebbles,  gravel,  and  sand  arc  in  abundant  quantity in the reservoir area of the Abbay - 21 site ,
2.5.73 Day Village (Dam Site Abbay - 12)
A. Litho lagy
Except that the ash  and  the tuff proportion  is increasing  downstream, the reservoir area is essentially  covered  by  similar rock  types (see Fig no,  9) as the other reservoir areas and  dam sites.  The geological cross sectian across the dam axis Abbay-22 is shown in figure 10,
15AJ BjmH
The basal! is much  thinner in  this reservoir area than  the other upstream areas and  dam situ.  Around  the dam site the bisaJi is vesicular with  prismatic feldspar phenocryst and  secondary  silica fillings.
A. l Tuff and Ash
I-
As observed  in  the field,  the tuff is louse and  much  weaker in  this reservoir and  dam site chan  the other two  sites.  In  some places a matrix  of scoria and  other pyroclastic materia] is found  exposed  along die river valley. However the ash comprises the major proportion.
B.         Structure
No major faults are found in the vicinity of the Hatti
C.          Cunscruction Miteriih
C! Rack Quarries
It  is  absolutely  impossible  to  open  a  quarry  site  within  the  vicinity  of the dam becauso
1) - the basalt is strongly weathered.
2) .  the basalt  occurs  as a  thin  layer  within  a  thick  succession of tuff and ash.
16C.2 Rher Bed Depoviu
The   sand,   gravel,   cobble,   pebble,   and   boulder   deposits   can   even   be thicker for this reservoir basin than the dims Abbay -20 and Abbay -
21. The approximate thickness of these materials can reach as much as
15  meters  (the  exact  evaluation  needs  pitting  Ln  the  river  channel  and valley sides).
2.6 HYDROLOGY 1,6,1 General
I
lite Bcshilo  river is one of the tributaries of the Abbay  (Blue Nile) river situated  in  the upper Blue Nile basin.  The river drains from the highland  areas of Wollo and its large pan of the catchment lies in Wadcla Dclanta Awraja.
The  headwaters  of  the  Bcshilo  river  catchment  are  highly  dominated  by  steep moun tai no us parts with rugged topography and dissected features.
The basin is highly degraded with only some patches of vegetation cover along 
the river banks. Large portion of the catchment area is prone to high erosion 
hazard and hence the sediment generation rate is extremely of higher
magniiudc-
Thc  Btthilo  river  is  ungauged  and  as  a  result  of  this  no  record  of  flow  and scdimcnl load data are available for the present study of the proposed sites.
The major stumbling  block  is conducting  (he studies was the problem of accessibility.  All potential sites could  only  be accessible by  air,  This was the problem which hampers the deployment of study team by land transport.
17I
HydmmdHMlogical stations are not yd  established  within  the sub-basin.  The sub-basin  requires dense network  of chose stations due to  the rugged  and mountainous features of the area.  This makes the assessment of water resources potential difficult and crude at the current phase of the study.
The headwaters part along  the water divide line of the basin  receive annual rain  fall amounting  to  1000-120thnm and  gradually  decreasing  to  890mm al the southern end.
I
2.6J Availability of River Flow Dita
There  are  no  flow  data  of  the  Beshila  river  that  can  be  resorted  to  the assessment of the water resources potential of the basin.
In 198 3 an attempt was made in establishing staff gauge and automatic water level recorder at about 50  meters downstream of the bridge that connects the road from Dessie to Wegelctcna but this was to no avail.
It  has  been  noted  that  during  the  short  period  of  observation,  only  two discharge measurements were taken on the 27* of April and 1“ of July
1983  After  a  link  while  the  operation  of  the  station  was  interrupted  by first  flush  flood  which  resulted  in  completely  washing  away  of  the installed  gauging  station;  todare  no  rehabilitation  works  is  carried  out on this station.
The only  option  dial can  be made use of is the transposition  of gauged caichment data to  the Beshilo  catchment and  to  some degree rhe application of region I ization approach.
18For  transposition  of  flow  data.  Abbay  river  flow  records  at  Bahir  Bar and near Kcwie for a period of concurrent observation from 1971 -
1984  has  been  adapted.  To  avoid  the  regulation  effect  of  Lake  Tana, the  sub-basin  enclosed  by  the  station  al  Bahir  Dar  has  been  excluded by   deducting   the   flow   contribution   to   Abbay   near   Kessic.   These hydrological data is found in Annex-5,
Further more,  it has been  attempted  to  apply  regionalisation  approach, For this purpose flow records of 19  gauging  stations situated  tn  the upper Blue Nile basin  with  varying  length  of records are used  for regression analysis.
The result of regression  analysis (linear one ) of mean  annual flows and  mean  floods in  relation  to  drainage area are found  to  be satisfactory  with  coefficients of correlation  which  is highly  acceptable for hydrological phenomena These relations can  be used  for determining  the above parameters in  the absence of nearby  gauged catchments or analogues.
2-6J Long term river flow series generation
Monthly  and  annual series generation  has been  conducted  using  the monthly and annual flow patterns of Abbay river flow near Resale after deduction  of the contribution  from the sub-basin  enclosed  by  Abbay  at Bahir Dar.
The  annual  series  are  generated  based  on  area-ratio  proportionality  and the monthly series are obtained by taking into account the monthly
19percentage flows of Abbay  river near Kewie excluding  the flow contribulion  of Abbay  st Bahir Dar.  Accordingly  synthetic flow data of Btihiio river at the selected sites for a period of 14 years starting from
1971 up to 1984 has been gcncraicd.
2,6,4    Availability and dependability of annual flow series
According  to  (he analysis conducted  the mean  annual flow and  95% dependable annual flow for the selected  sites are found  to  be of the following magnitude.
Site
Catchment ira (km )
5
Mean annual flow(m /s.)
3
95% dependable Annual flowftnVs)
Abbay-20
Abbay-21
Abbay-22
3548
4728
5136
22.75
30.56
33.16
9,03
1120
1324
1
The    catchment    area    of    Abbay    river    near    Kcssic    excluding    the catchment area of Abbay at Bahir Dar is 50463 km ,
Based  on  this  result  the  95%  dependable  annual  flows  are  found  to  be about 40 pecten! of die mean annual flow,
Abcul 90% of the annual flow is concentrated  in  the months of July  to October and  considerable amount of the flow occurs in  the months of July to September which is about 85% of the annual flow.
202.6.5    Results of Amlyib
The results obtained in the course of the analysis are toore of indmamc emes which  would  subsequently  enable Id further assess the water resources situation  of the totally  mgaugod  caTChmetn  of the Beshilo river.
It hu  been  learnt that for quite short period  of time staff gauge and automatic water level recorder were opentiorul upstream of dam site Abbay-2Q (catchment area 3  598  Knr) which  gave the foliowings TESultS>
Station
Date
Discharge (m’A)
Beshilo river Mar Wegeletcna
April 27“ 1983
July 1' 1983
3J9
122
According  to  the analysis of the synthetic data obtained  for dam site Abbay-20,  the mean  monthly  flow of April is about 2,l6m‘j's and  the mean monthly flow of July is found to be about SJ.Otn'/t, But the How- recorded  on  the I*  of July,  1983  seems unrealistic,  incorrect and  gives a different picture when  this is competed  against the potential catchment area and  period  of the rainy  season.  The flow magnitude should  have been  of higher order,  the cause of this could  be the lack of frequent inspection  of the gauging  station  after its establishment.  It is therefore felt that the two  flow records could  not practically  used for comparison  purpose^ gross errors has been  nude in  the July  r, 1983 measurement.
21The tranipOiition  of Flow dara of Abbay  river nor Kessje >jj been conducted  after deduction  of the flow comributiOO of Abbay  H Bihir Du  which  w-ould  otherwise have ID »mt extent the regulating  impact of Lake Tana as is contained  in  the sub-basin.  The regulating  effect of the Jake is highly  pronounced  in  high  and  low flow co&ditiaBs which Will result in  reducing  the flood  peaks and  augmenting  the Jan  period flows.
Statistical analyses of the synthetic annual flows goemed  far the proposed  sites arc conducted  and  the nonmJ dinribuuotu  is selected for fitting the empirical points of the flow scries.
At this level of the study,  correction  factors fix  spatial variation  of rainfall,  orographic effects and  physiographic conditions are tM< taken into  Account while generating  the flow series due to  the absence of Urge scale maps (1:50,000),  Meteorological and  hydrological data An atteoipt has been  ^mnic to  establish  cexroctioc factor for spatial variation  of rainfall with  respect to  Abbay  basin  near Kessk  without including  the tub-basin  i.o  Abbay  at Bahir Dar and  the factor is approximately  found  to  be 0.8.  This requires further refinement and taking  account of other factors before applying  to  the present level of the study.
Considering  the average conditions of the uichmcfit^ the annual runoff volume that could  be generated  from them L  about 20% of the mean annual rainfall.
121.6.6    Flood Estimation
Flood   analysis   his   been   conducted   after   transposition   of   (he   flood records of the Abbay river near Kesiie io the specific sires
In  order to  attach  return  period  concept to  the flood  magnitudes, statistical analysis of probabilistic approach  has been  applied  and  the results are available in separate computer outputs.
Regional analysis of floods has also been earned out to establish 
relationships between mean maximum Hoods and drainage areas. The
results arc found to be satisfactory fur estimating mean flcods of
ungauged catchments in (he absence of nearby analogue gauged 
catchment
For estimating momentary peak flood from mean maximum daily 
floods, peak factor of 1,5 can be considered in transforming mean flood magnitude with different return periods tp instantaneous peaks.
The Gamble type I distribution  has been  selected  for fitting  (he mean flood  series of the proposed  sites and  the magnitudes of the 1000  year and IOOQQ year return period floods arc is follows;-
23Site
Magnitudes of flood using mean values
(tufa)
Magnitudes of floods applying peak factor of 1.5 (ft?/s)
Based on
regional
analysis
cv=0.4
Ofn for 1000 yr=2.6 
Qmear.
OTT] for 10000yr-3 
Qmean
AB-20
AB-21
AB-22
Qjnx * 760
Qua = MO
Qw = 1020
Q  - 1270
im
Qt„ = 1100
Q  = 1370
iaw
1140
1410
1530
1905
1650
2055
1170
1360
1500
1730
1600
1850
16.7                  Daih flow Duration Carvc
In  the  current  analysis  of  flow  regulation  work  average  year approach of flow duration curve construction has been adopted.
This method  takes- into  account the absolute minimum and maximum flows for the recorded  period  and  the average year conditions,  Based  on  this approach,  flow duration  curves of the proposed  sites has been  produced,  (refer to  figure 24,25,26  for Abbay-20,21,22 respectively]
Flow duration  curve reflects the flow regime and  its natural regulation  which  is determined  by  geographical zonal distribution  of flow and  factors of the surrounding  (catchment area,  its altitude,  Sakes,  marsh,  forest,  soil,  hydrological condition and tic).
24Sediment Eatimatton
The absence of measured  data regarding  sediment load  in  the study  area has left the present level of the study  to  rely  on world  wide experience of reservoir sedimentatinn  which  can  be provided  tn  the range of LO-25% of the gruss storage as dead storage provision.  The rate of sediment generation  from the watershed  is expected  to  be extremely  high  and  difficult to  get reliable means of predicting  the inflow sediment rate into  the reservoirs in  the form of suspended  sediment and  bed  loads. This is mainly  due to  the steep  slopes of the topography,  the exposed  nature of the soil to  erosion  hazard,  land  cover condition  and  degraded  nature of the environment as A whole which  will contribute a great deal in  the production  of extremely high sediment inflow rate from the catchments^TiM« Ml 11
1^4
rtnni rf the uppQ Blue Kite tall
in-fn ■**?>'“ 
™* «—d
™*
-*km
Ng
Nw </ n*w
Uk*4xm
DfWffo tn*
lira')
Type of HydndmCTJ
SUkki
Rmjufri
M.
*UL
ELOC
t
!2
1
4
5
6
T
*
9
10
II
12
IJ
' 14
IS
IS
11
JI
19
limb®
AWW
□aate
<MMi
Xdtu
Chib
Bnp
I4o4l«u
A*im*
Mup
M«Mli
Omtwr
T«m
S4*
AMv
ET= f~fa ■ iw krt
■Ti CbMCtaH
■r CUocAd
■ ClWMbfr
M.A14S
■T. Muntin v. C"k«Aa u. MiLuwt
■f. AMii Abn
■'. HoU*
M Ruiniw
■r l'Mu
If. Lkspa
if Mui
«r Kite
v Ln
■ Nfcu
■ . Emlra.
■
JM
419
29
U
B44
MT
<11
742
2fl
119
CTJ
111
JT5
2W
1749
«?
J MJ
I»
5OMJ
X
X
x
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
OHC
□«w AwiM
Upa A™*
________ 3.
Hu Dprwhmti
hn.1^
Ow bead cbta*vy
NjL-
S.G-       Sun jA-tL*
W.LK’       Mp'a&g fcvd rofcoriae Il-.Jj.C-     Hajftli Lyniisl fr.A|jj O.HX’       CXn-  btM ubkiMy
26DESCRIPTION OF DEVELOPMENT & ALTERNATIVE layout
1 study elocution
The reconnaissance studies were parried  ou1  through  a coordinated  program of office studies and  field  investigations,  The work  program started  a; the beginning  of March  1995,  however the Desk  Identification  studies were not performed  initially  before the field  work  program.  Preliminary  project layouts of project structures were not established  using  existing  topographic maps and aerial photographs.  More of the office studies wen; performed  in  the field  and initial data and information were fully adopted from the WAPCOS Study ,
Based  on  the 1:250,000  map  and  aerial photograph,  different field  activities for the study  were arranged  and  an  mitral site investigation  program were made during  Majch  17,  upto  April 22,1995.  This field  execution  were initially arranged  by  vehicles,  unfortunately  the accessibility,  the remoteness and  their particular terrain  characteristics made the visual survey  impossible to  be conducted  on  foot or using  vehicles.  To  cover the extensive area of the project and  to  minimize the time frame,  helicopter flights were arranged  into  th? gorge for the main  dam sites.  However,  the field  work  was executed  in  a one day scheduled  by  helicopter on  April 21,  1995  (afternoon) and  April 22,  1995 (morning).
In  the course of the study  topographic and  geologic assessments,  present runoff condition,  accessibility  of the site in  respect to  the proposed  darn  sites, collection of some information on sociology and environment were made to
27identify  in  particular,  the major geological units in  the gorge &.  the potential of the river for Hydropower tn  respect to  its effect on  the social A environmental impact No  specific investigation  for foundation  conditions and waterways alignments were carried out
During  the site verification  works,  the cross sections of the dam sites and longitudinal profiles of the river for 58  km length  were established  using  the GPS (Global Positioning  system ) equipment provided  in  the helicopter.  This covered  the areas between  dam site Abbay-22  to  reservoir end  of Abbay-20. Figure 11 shows the longitudinal river profile along the river resulting from the Survey  made by  the GPS,  adjustment of the data with  1150,000  soak  were done and  this topographical profile needs to  be reassessed  oe re-survey  in  the future studies.
3.2 Devdopmrjjt Concept
In  most of the high  head  and  medium head  Hydroelectric projects,  a dam- across a river is an  important component.  Very  often,  the cost of this single component may  be as much  as 20  to  25% of the total financial outlay  of a hydro-electric project.
The selection  of a site for a dam depends upon  the function  of the dam From cost consideration,  smaller the length  of the dam,  less are the costs.  Hence the site should  be selected  in  a narrow valley  for storing  maximum water with minimum construction  Besides the function,  aesthetic beauty,  availability  of labourers and construction materials, the major serious concern is the
28accessibility   of   the   project   area   from   the   view   point   of   transportation   of materials  throughout  the  year  The  roads  will  be  required  to  facilitate  the  pre feasibility   and   feasibility   studies   and   transport   materials   during   consmtetion periods  and  to  economically  connect  the  sites.  Along  this  line  (he  other  point of  concern  which  needs  special  attention  in  the  value  of  land,,  property  and township  Io  be  submerged  by  the  proposed  dam  which  has  to  be  as  low  as possible.
A hydropower generation  scheme which  is considered  as mofl suitable and favourably  in  the Ethiopian  conditions is the Ivlultisiagc Hydroelectric System'.  In  this system,  the river is divided  into  several successive reaches with  a dam at the downstream end  of each  reach,  Various types of storage dams for hydropower as dictated by the topography art listed below:-
i.           A dam with power-house built at the toe of the dam
(dam - powerhouse),
ii.         A dam with isolated powerhouse located other on the surface
or underground.
iii.        An open flow diversion system.
iv.        A pressure tunnel or water conduit system
D*rn Vrilh Powerhouse al Toe (dam ■ powerhouse)
In  such  type of plant arrangements (dam-powerhousej.  the intake and other water conveyance structure arc usually  provided  in  rhe body  of the dam.  The penstock  are embedded in the dam and feed water to the powerhouse at the toe of the dam.
29Dam With [touted Powerhouse
Wherever conditions permit,  an  earth  or rockfill dam tan  be built with a powerhouse located  away  from the dam.  The powerhouse is fed  by an  tndependenl pressure tunnel with  an  intake structure on  the upstream and  a gate shaft and  control room on  the down-stream end  of the ridge. The tunnel continues and  feeds the powerhouse located  at a convenient site downsueam.
An Open flow Diversion System
The distinguishing  feature of the diversion  canal plants is that the waters of the river are diverted  away  from the main  channel through a diversion  canal refereed  as a power canal.  Diversion  canal plants are, generally  speaking  low head  or medium head  plants,  like run-of-river plants.  They  do  not have any  storage reservoir,  The powertousc requirements of poundage are met through a pool called a "fortoay".
A_Prgssure Tunnel or Water Conduh System
Water enters the conveyance system through  the intake structure located  at the dam depending  upon  the general topography  of the terrain,  this conveyance system may  lake the shape of tunnels,  canals, flumes or pipes The other important factor is the geological fomiation of the ground  which  ii a decisive factor for the construction  of canals and tunnels.i
The major features (hat create the Beshifo  project are a combination  of Trservoir (river valleys) located  upstream from the Jila valleys and  the formation  of head  developed  by  the construction  of dams.  From a study  of the topographic maps,  aerial photographs and  field  investigation,  the potential of Hie over is only  favourable for Dam-Powerhouse type of arrangement.  This is due to the following features of the river valley such as
1.         The river slope is moderate and no falls throughout its length.
2.         The topography of the banks i.e dissected by gullies and streamlets -
3.           No  possible  penstock  route  arrangement  found  from  the  topography (generation of head from the topography is low).
4.           No  possibility  of  gening  sufiitient  space  for  an  open-air  powerhouse with natural head from the topography.
5.         Pushy nature of the river which needs storage for the dry period
6.         Spatial distribution of the rainfall over the area is limited.
The spillway  is an  important part of the dam complex  and  is located  either as > part of the main  dam or separately  at a suitable place near the dam This structure is highly  dependent of the topographic condition  of the valley.  The Bcshilo  river valley  is typically  of a channel type that have a high crust width a1  the proposed  dam sections.  In  a narrow valley,  where the required  crest length  of the overflow spillway  is not available side spillway  is convenient. Due to  topographic reason  and  less space occupation  the Saddle Siphon  type spillway is recommended for the Brshjlo valley.
The Btshilo river Geological condition is uniformly distributed over the valley. This uniformity is due to the formation of the trap scries volcanic rocks of highly weathered and jointed basalt, basic tuff and ash. The formation of a
31deep  gullies and  absence of good  head  from die topography  with  an  open  air powerhouse might lead  id select a storage dam of concrete type or rockfill with  spillway  incorporated  in  the dam or located  on  the roof of the powerhouse (dam - powerhouse).  This consideration  has an  impact on  the design  of Hydropower plants and  arrangement of water ways.  Thus the Bcshito  valley  is preferably  adopted  for a Dam-Powerhouse schcnse with siphon type spillway.
3 J      F.i lent of Developmcni
As per the WAPCOS Studies had  identified  different hydropower potential sites on  the Abbay  basin  located  near Wegel Tena town..  The radium scaJe hydropower potential sites (Abbay  20,21  & 22) along  the Bcshilo  river were investigated  under this study,  These potential sites and  their particular drainage area are shown on figure 12,13 & 14.
All the above mentioned  alternative sites are Located  doser lo  each  other.  The sites were found  extremely  wide at the bottom compared  to  the crest of the dam at a heighi of 100m from the bed.  Following  is a brief remarks and comments on  the physical conditions likely  to  be encountered  for each proposed site.AItcrnative    Layout
14J Site Abbiy-2O - Scheme One
3.4,1.1              Dim Site
The river form*  generally  a wide U-shaped  valley  with  steep  slopes of about 40-45  degrees.  This potential site was inspected  with  the following  co-ordinate readings of 11°24'  15” N,  3Q°02'  21“ E  al left hand  embarkment and  1r 24'31" N,  39“ 02'  10" E  at right hand  embankment with  a barometric altitude of 1545 m on the bed of ifur river (see Photo No. 19).
During  the first inspection  of the site from the air,  it became immediately evident that the site and  its tributaries have a low hydroelectric potential which could  not be economically  developed.  The geology,  head  generation  possibility and  arrangements of dams and  associated  structure*  were nol attractive at the outset The valley  is relatively  wide,  though  the bank*  slopes are steep.  The bottom width  i*  about 260  meters whitest the crest width  is 610  totters at 130 meter elevation from the bed (sec figure no. 15).
The topographic (river diversion) and  the available foundation  condition indicate that a concrete dam would  be preferable.  However taking  the length, height and  treatment of the dam foundation  required  into  consideration,  the proposed  site would  not be economically  developed  with  respect to  Medium Scale Hydropower development.
Moreover,  Looking  at the availability  of construction  materials and  the natural topography  of the site,  a rockfill dam is a feasible option  which  need  to  be considered seriously. However, the requirements of foundation treatment alongwith  the  effect  of  vibration  due  to  the  turbine  (dam-powerhouse)  should  be looked into in detail.
Si ikc sufficient quantities of core material arc nol readilly  available in  the vicinity  of the proposed  site,  a concrete face rock  fill dam with  extensive treatnJtrti or excavation  of the tuff and  ash  is recommended.  Due to  non availability  of suitable earth  fill material, earthfill type of dam is automatically rejected at the outsit
Spillway  construction  would  constitute a major cost component in  this valley. Considering  the high  fhashy  type flood  and  relatively  small reservoir volume compare to the dam height, the volume of spill is high.
From a perspective layout and due to topography (no saddle along the banks)
the spillway construction would be in a rock and excavation cost is high. So 
their location should be incorporated in the dam or oo the roof of the
powerhouse. Protection of powerttouse is a major problem in this type of
design. However Siphon type spillway is a major solution for this type of
topography.
3.4.1,1              Headrace
The left and  right side banks of the valley  are extremely  steep,  frequently foiming  near vertical rock  faces and  additionally  the valley  is dissected  by numerous deep  gullies and  tributaries.  On  such  steep  stopes excavation  of a canal is technically  infeasible and  construction  of tunnel would  require a number of conduits. Thus both banks of the valley appears not suitable for the alignment of the headrace canal or tunnel (see photo No, 20 & 21).
343.4,13                Penstock
The possibility  of Penstock  arrangement due to  the topography  ia not feasible in  the Bcshilo  valley.  Generation  of good  head  from the topography  is low. The gtotogy  of the valley  is almost the same.  The area is covered  by  highly weathered  basalt,  tuff and  ash  this may  create problems for the foundation  of the anchor blocks As mentioned  above the weathered  basalt,  tuff and  ash  are highly  friable and  erodibk  during  saturation  which  may  have the potential for major slope instability.  Therefore,  the possible arrangements of the penstock would  be embedded  in  the dam body  and  feed  the water to  the powerhouse at the toe of the dam
3.4.1.4               Pawerhouu
The river throughout its length  is highly  dissected  and  generation  of head  from the topography  is low.  The possibility  of getting  sufficient space for an  open- air powerhouse with  the natural alignment of penstock  route is infeasible.  The dam-powerhouse option  is expected  to  be feasible solution.  Geological observation  made on  the proposed  powerhouse location  proves that the dun site foundation dominated by tuff with ash and weathered basalt
3.4.1,5 Reservoir
Depending  on  the size of the dam and  hydrology  a reservoir would  be created which  could  provide storage volume probably  even  for a full regulation  of the river flow.  However the reservoir created  by  the dam ai Abbay  20  is a channel type storage and  would  be too  small to  sufficiently  effect river regulation (sec figure No. 18 ).
35From the observation  made in  die field  (he Abbay-20  dam site is just below the faull line that occurs parallel to  the dam axis (rec figure no.  7).  The extension  and  the depth  of this fauh  is not known.  Therefore do cvidcn«  was detected  to  predict the leakage through  the tiam or along  (he fault into  a neighbouring  catchment.  This embankment slopes are generally  very  sleep. Rock  fall and  landslides due to  saturation  of the weathered basalt, tuff and ash have been  observed.  This would  indicate instability  of the reservoir rims that needs special attention.
5.4J 6               Construction Materials
Massive  basalt  would  provide  abundant  quantities  and  good  quality  of  rockfdl Earth  fill  and  core  material  is  not  available  in  the  area,  Also,  natural  alluvial material  appears  to  be  not  good  quality.  Basalt  would  have  to  be  crushed  and processed  to  obtain  the  required  quantities  for  filter  and  aggregate  material During   site   investigation,   construction   materials   have   been   located,   which includes  sand  and  gravel  cobbles  and  pebbles.  The  possible  quarry  site  is situaicd  al  about  6  kms  from  the  dam  site,  These  proposed  quarry  material extends for about 14 kms upstream of the river.
34,1,7 Estimated power potential
rhe site command® a drainage area of around 3548 km1 for which the average long-term annual run-off is estimated  m be 23.07  mVs.  The flows for probability  cxcedenct of 50%,  90% and  95% are considered  3.5  m'/s 0,56  m’/s and 0.29 mVs respectively, indicating the large variability in flows over theDue ID the [smiled  topography  Available At thia study  level an  actual elevation-
area-sioragc relationship  for the selected  Medium Scale Hydropower sites has
not yet been  established.  To  overcome this limiiadons,  elevation-area-storage
curve were developed  for all sites,  from formula adopted  for Gilgel Gibe
Hydropower pre-fcasibility study (i.e V = 1/3 X {F  + (F, X
(
+FK|} X
I 1
I I ] I I 1
] ] J
1
(h,.,-hj  +  V|  i  whcre  Fi  A  *  *  *  *  &   are  area  al  h<  &  hw   .  V,  is  volume  ).  Figure No. 18 shows the elevation-storage curve of this result.
The power estimation  was done using  the EVALS.'EMINl program of Lahmeyer International which  is used  io  evaluate hydropower projects based on  costing  ,  dimensioning  and  evaluation  of this information.  During  this optimization  a rockfill faced  concrete and  a concrete gravity  dam alternatives were analyzed.  This alternatives were inspected  with  different ICF (Installed Capacity  Factor,  i,e ratio  of total turbine discharge capacity  over the mean annual flow) and  these results arc summarized  in  Annex-1  of the EVALS summary.  From this result a minimum cost for a larger energy  with  a better guarantee of this energy  for a minimum generation  cost were selected.  Thus the Rocktill faced  concrete dam seems feisihlc compare to  the Concrete gravity dam,
As a result, a rated head of 73.0 m, and a total design discharge of 46.1 mVs of the two turbine (Francis) at a plant factor of 30.5% were analyzed. The potential of this lite is approximately 46.0 MW. The mean Installed Capacity that could be economically exploited for this site is 29,5 MW . The guaranteed capacity is 22.21 MW. The energy corresponding to the mean capacity is 86 GWh at a 50% guarantee (see Annexe of EVALS summary),
37Preliminary  analysis indicated  a storage of some 511  MCM volume could  be realistically  developed.  Results of this Rockfitl dam alternative has a 32*/* degree of regulation  with  a corresponding  longterm spill over total inflow of 34.1% {see Annes-1 of alternative F).
All  die  above  assumptions  and  analysis  should  bch   refined  because  the  field investigation programm was not enough for detail work.
38MAIN DATA
SCHEME ONE (AfiBAY-20) 1. DriLnigt Basins
- Drainage areafkm*)
- Mean Annual 2. Reservoir
Eievatka
Abbay-20
3548 23.10
-Mm. reservoir kvel(MSL)
1626.00
-Mean reservoir ]cvcl(MSL)
1621.20
-Min. reservoir IcvclfMSL)
1606.00
-Dead storage tevelfMSL)
1560.00
Area
-At max. reservoir ievel(W)
8.50
-At Dead storage levelfion )
1
5.42
Storage
■Ai max, reservoir leveHMCM)
550.64
■At min, reservoir IcvdfMCM)
385.0E
■Active storage volumcfMCM)
165.60
-Degree of regulation
32.2%
1 Daras
Type
Max. Heighten!)
Refill Faced Concrete
92
Crest length(m)
509
394. PeniCflck
Type
Lcnglh(m)
Steel, embedded in the dam
170
5. PowtrhauM
Type
Surface
Number of Unit
2
Generated Capadty(MW)
-Maximum
32.26
-Mein
29J1
■^Minimum
22.21
■99% Guaranteed
22.21
Energy (out put in GWyr)
-Maximum
104.0
-Mean
86.3
-Driest YorfFirm energy)
472
Turbine
Type
Installed Capacity(MW)
Francis
2 X 14 .9
Total design dischargefmVs}
46.1
Rated hcad(rri)
73
6, Transformer] Number
Type
2
Oil immersed 
Self Cooling
407. Truism Istluo
Number
Voliage(KV)
Length (km)
3,4,2 Site Abbav-21 - Scheme Two
3,4X1 Dam Site
1
132
120
While flying  along  the river valley  downstream the river course from Abbay-20  site,  it was found  that the actual gradient of the river i* relatively  low.  ThiB situation  has,  therefore,  called  for for the creation of artificial head with the provision of a dam.
The river forms a wide, u - shaped valley more or less same as Abbay-
20  dam  site.  This  potential  site  was  inspected  at  the  following  co ordinate  readings:*  H  •  22  ’  31"  N,  38  *  53’  28"E  of  the  left  hand embankment    and    11°    22'44"    N,    38’S3‘46"E    of    the    right    hand embarkmem  with  ■  barometric  altitude  of  1440  m  on  the  bed  of  the river.  At  the  proposed  dam  site  the  valley  is  relatively  wide  and  the banks  slopes  are  steeply  inclined  al  angles  of  about  40  -  45  degrees (see  photo  No,  22).  The  width  of  the  river  bed  is  about  340m  and  the west width, at a 130 m height above the bed of the river, is 690ra {see figure  no.  16),  All  the  readings  are  taken  using  the  helicopter  GPS (Global positioning systan) equipment-
A dam of considerable volume and height would have io be constructed in order to create the required hydraulic h^d. This is because the
41topography  does not allow the possibility  of constructing  headrace canal or tunnel with  natural penstock  layout At the selected  site,  the river channel is almost similar with  Abbay-20  and  highly  entrenched by  deep  tributary  streamlets.  The construction  of canal or tunnel into such  valley  would  be very  difficult since this arrangements call for additional structures (conduit}. See photo no,23 & 24.
Cost of such  structures including  river diversion,  apputtenant structures, vol ume of excavation and/bf foundation treatment that would be needed in  view of the thick  river sand  may  certainly  exceed  the usual estimate allowed for MHPP within the engineering norms.
The valley  of the proposed  site is filled  with  sand  which  may  exceed IQ - 20  meters in  thickness.  Tuff and  unconsolidated  volcanic ashes and  little pyroclastic with  intercalated  basalt am also  observed.  The over burden  cover is generally  very  thin  w completely  absent.  Alt dam sites have similar foundation  condition,  only  differing  slightly  in valley shapes.
All the above investigation  and  the topographic condition  (river diversion},  indicate that a concrete faced  rockfill dam or a concrete gravity  dam would  be preferable,  However,  cockfill dam construction would  not be economical due to  the un-availability  of the rock  quarry in  the vicinity  (sec annex  2}.  As previously  explained  for the other sites,  similarly  the quantity  ind  the quality  of eanhfill materials are not found Ln the vicinity, so the construction of eanhfiU dam is also not feasible.
4214.2,1               Headrace
As explained  above for dam site Abbay  20,  the geology  of the valley is almost the same.  The left and  the right side banks of the valleys at the proposed  site forms frequently  near vertical rock  faces and  the valley  is highly  dissected  compared  to  the UZS side of the rims (sec photo  No.  24).  Both  banks of the valley  appears not suitable for the alignment of water ways.
S.4JJ                  Penstock
Possible penstock  arrangement u  also  not possible and  feasible due to the topography  in  the Bcshilo  gorge.  Since the surface geology  in  the valley  is covered  by  highly  weathered  basalt,  tuff and  ash  there may create problems fur foundation  of the anchor blocks and  slope instability.  Thus penstock  arrangements should  be at the dam toe which would be embedded in the dam body.
14.2.4 Powerhouse
The valley  around  this proposed  site is less dissected  compared  to Abbay-20.  The possibility  of getting  sufficient space for an  open  air powerhouse with  the natural location  of penstock  route is infeasible. Dam-powerhouse option  is the only  feasible solution  for this site also The foundation  condition  is dominantly  covered  by  the intercalated  tuff and ash.
!
i
»14.2.5                 ftrtervoir
Going  upstream from the face of the proposed  dam Site,  the width  of lhe Bcshilo  valley  gradually  widens and  at ±e tttd  narrow?.  This site has relatively  a better reservoir storage capacity  than  Abbay  20  (wc figure No. 18).
The right hand  side of the reservoir rims arc less in  height compared w the left hand  aide.  Any  further increase in  dam height would SUbsequendy increase the dam Crosl which could entail additional CoSt.
The reservoir slopes are generally  similar to  that of Ab  bay-20  which have very  strep  slopes.  Rockfalls and  landslides due to  saturation  of the weathered basalt, luff and ash would he expected.
14.2,6 CnnsimctioB Material
During   site   investigations,   the   available   construction   materials   such   as sand and gravel, cobbles and pebbles have been located in abundance.
However,   the   quarry   site   for   the   rockfiU   is   not   located   within   the allowable and economic hauling distance.
.14,2.7                Estimated power potential
For  this  scheme  the  main  pararoeters  used  determine  the  proper  types of dams are die availability of construction maLsri aJs, geological
44conditions of the foundation  and  minimum project cost with  minimum generation  costs at 50  or more percentage of guaranteed  energy.  Based on  the above parameters a concrete gravity  dam and  a rockfill dam faced  with  concrete were analyzed.  However due to  the long  hauling distance involved  in  developing  the quarry  site for such  volume of work.'the rockfill dam and  corresponding  generation  costs have proved to  be very  high.  This option  is,  therefore,  rejected  at the outset Instead,  a concrete gravity  dam has proved  to  be feasible and recommended  for this site.  But geological condition  of the dam site is doubtful to resist this much volume of concrete.
Abbay-21  commands a drainage area of around 4728 km2 for which the average long  term run  ofT  is estimated  to  be 31.0  mVs.  The flows for the probability  of cxcedence of 50%,  90% and  95% are estimated to be 4.70  m’/s 0.76  m*/s and  039  m’/s respectively.  This figures shows the variability of the flows,
All possible alternatives were assessed  and  analyzed  with  different ICF and  the out put of this optimization  are summarized  in  Annex*2.  From the outputs a rated  head  of 70.5m and  a total discharge of 61.9m‘/s from the two  Francis units at a plant factor of 31.4% were analyzed. The potential of this hydro  scheme is approximately  633  MW.  The mean  installed  capacity  for this site is 38.9  MW while the guaranteed capacity  is 30.7  MW.  The energy  corresponding  to  the mean  capacity is 118 GWh with a 57% guarantee (sec Annex-2 of EVALS summery).
Preliminary  analysis indicated  a storage of some 982  MCM volume could  be realistically  developed.  This concrete gravity  dam alternative has a 38% degree of regulation  with  30.7% corresponding  longterm spill over the inflow (see Anncx-2 of page 5).
45MAIM DATA
1
SCHEME TOW (ABBAY-21)
I, Drainage Bum*
- Drainage areafkm )
- Mean Annua] flowftnVs)
L Reservoir
Ekvatkin
-Max.  reservoir IcvelfMSL) -Mean  reservoir levelfMSL) -Min. reservoir level(MSL)
-Dead storage tevel(M$L)
Ana
-At   max.   reservoir   teveltkm1) -At Dead storage levelfkn?) Storage
Abbaj-2I
472® 31.00
1520.00
1514,80
1496.00
1450.00
16.23
10.77
-At max.  reservoir level(MCM) -At min.  reservoir lcvcl(MCM) -Active storage volumc(MCM) -Degree of regulation
3. Dams
Type
Max. HeighHuj) Crest lcngth(m)
1057.97 703.47
354.50 38.0%
Concrete Gravity
92
582
464, Penstock
Type
Length(m)
Steel embedded in the dam
150
5.    Powerhouse
Type
Number of Unit
Generated Capacity (MW)
-Maximum
-Mean
Surface
2
-Minimum
-99% Guaranteed
Energy (out pul in GWh/yr)
-Maximum
-Mean 
■Driest Year^Firm energy)
Turbine
Type
Installed CapacityfMW)
Total design discharge(mVj)
Rated hcad(m)
42.89
38.94
30.69
30.69
143.9
118.1
68.8
Francis
2 X 19.2
61.9
70.5
6.  Transformers.
Number
Type
2
Oil Immersed self cooling
477,  TraasmBsion
Number VqliagefKV) Lcng(h(km)
1
132
150
3.43 Site Abhay-22 Scheme Three
14At                Dam She
Site Abbay-22  is located  about 15km downstream of Abbay-21.  'Ihc river at this site flows th  through  a relatively  narrow valley  compared  to  the other potential sites (Abbay  20  & 21).  The physical topography  Jong  this stretch (between  Abbay-2) and  Abbay-22) allows for rockfill type of dam in comparison  to  others.  As previously  indicated,  the height of (ht dam is also limited  by  the available height of the right bank  topography.  The EnaxnnuiQ height that could be exploited for the intended purpose at this specific site is
130  meters,  Any  additional  increase  in  height  beyond  this  would  substantially increases the crest length of dam. as well as the cost (sec photo No. 25 ).
Hie Valley  is generally  forms u-shaped  with  steep  slope of about 30-40 degree.  The barometric altitude of this site is 1350m at the bed  of the river. This potential site was has the following  co-ordinates readings of lla25'56"N, 
38 42’54'E 
n
of    left    hand    embankment    and    ir2S'15,rN,    38’42I9’,E    of    right
hand embankment.
This  site  is  located  just  before  the  confluence  of  Jita  river  to  Beshilo  river. The visual inspection made on site had proved this site seems attractive from
48the point of view of the valley.  The geological condition  and  provision  of acccis to  the powerhouse have been  observed  as the major point of concern on  this site.  The river bed  width  and  crest length,  at 130  meters height above the bed,  have been  recorded  to  be 210  meters and  620  meters respectively  (see figure No. 17).
The prevailing  foundation  conditions and  the absence of sufficient quantity  of tarthftLl material call for a rockfitt dam or a concrete gravity  type of dams. The later option  would  be very  expensive due to  unavailability  of the mck quarry  site in  the vicinity.  A considerable arrxsunt of excavation  and?'  or foundation  treatment would  be expected  in  view of the thick  sand,  gravel deposit and weathered basalL
One more additional site has been  identified  about 2  kin  downstream of site Ahbay-22  (see photo  no.  26).  This site,  alternative dam site for Abbay-22, could  also  be developed  for the intended  purpose bul the geological and topographical nature are similar to  Abbay-22,  Detailed  investigation  were not carried  on  this site except some cross sectional survey  and  observation  of surface geology were done.
3-4J.2 Headrace
rhe level of this studies didn't allow for detailed  geological investigation  to come up  and  recommend  under ground  structures for the headrace. Nevertheless,  the left and  right hand  banks were investigated  but sound  rock foundation  was not encountered  in  which  to  establish  a portal and  tunnel structures,  Due to  a number of gullies dissecting  the river embankment,  and steep  side slopes,  the construction  of canals have been  proved  to  be not feasible. Phoio 27 and 28 clearly show this situation.3433                Penstock
The main  dictating  factora for the penstock  arrangement (surface or underground} is the topography  (for the required  head) and  the geology  far the firm anchorage of the penstock.  The site has a very  friable and  weak material io  place the Anchor blocks.  As previously  explained,  the topography limits the layout for the penstock to be embedded in the darn.
3.434               Powerhouse
The available topo  maps and  the aerial photographs have proved  that the river gradient down  stream from site Abbay-21  is gentle and  flat.  There is no  any potontra] head  that could  be exploitable from the stretch  of the river course. These property  of rhe Valley  therefore leads the arrangement of the powerhouse location al the toe of the dam site.
3435                Reserve tr
Because of the topography and the uniformity of the geology along the river, a similar assessment wu carried out. Thus problems of land slide and rockfall would also be expected on this site. Concerning the reservoir regulation capability, this rile is relatively more effective to regulate the flows compared to the other potential sites..
343.6 Construction materials
As it was observed in the field, the availability of construction materials is scarce in the vicinity. This is due to the occurrence of the basalt as a thin
50!
J
layen within * thick succession of the tuff and uh. Should this site is selected for implrmenlation, construction material could only tfiide available from areas anwind dam site Abbay-20 (i.e 36 km far from the dam site Abbay-22).
3.43,7               Estimated pqwer potential
This site has relatively a tarter drainage area of about 5136 km for which mean annual run off is estimated to  be 33.16  mV;.  The flows for the probability of exccdenceof 50%, 90% and 95% are considered 5.10 m7s 0.82 m’/s and 0.42 m /$ respectively, indicating larger variability tn flows over 1he year.
Due io the limited topography available at this study level, an clcvatiQivarca- storage curve were developed similar to Abbay-20, The power estimation is also done with the same method applied for the others,
This analysis resulted in a rated head of 73.9 m and a total discharge of 67.2 m'/s for the three Francis units at a plant factor of 30.8%. The potential of
this site is approximately 68.5 MW. The mean installed capacity for this site
is 44.56 MW whilst the guaranteed capacity is 31,0 MW. The energy corresponding to die mean capacity is 130 GWh with a 49% guarantee (see Anncx-3 of EVALS summary)
Preliminary analysis indicated a storage capacity of some 562 MCM volume could be realistically developed. This concrete gravity dam alternative has 32% degree of regulation wiih 33.7% corresponding longterm spill over the inflow (see AniH3t-3 of page 5).
51I
MAIN DATA SCHEME TH REE (ABRAY-22) 1. Drainage Bastes
■ Drainage area(km )
- Mean Annual ilowfmVa)
1 Reservoir
Elevation
Abbay-22
5136 33.60
-Ma*, reservoir lcve1(MSL)
■Mean reservoir levcl(M$L)
■Min. reservoir Lcvel(MSL)
-Dead storage lcvelfMSL)
1430.00
1425.00
1406.00
1360.00
Are*
■At ma*, reservoir Icvelflan*)
-At Dead storage leveifkm )
1
10.33
5.45
Storage
-Al max reservoir IcvelfMCM)
-Ai  min.  reservoir  IevcI(MCM)
-Active  storage  volumc(MCM)
-Degree of regulation
600.87
364.05
241,30
32.0%
3.   Dam
Type
Mi*.  Heigtit(m)
Concrete gravity danj
92
Crest length(m)
493
524,   Penstock
Type
Length(m)
5.   Powerhouse
Type
Number of Unit Generated Capacity^MW)
-Maximum
-Mean
-Minimum
■99% Guaranteed Energy (out pul in GWh/yr)
-Maximum
■Mean
-Brie st YcarfFirm energy) Turbine
Type
Installed Capacity(MW) Total    design    dischargeTj) Raied head(m)
6. Transformers
Number
Type
7. Transmission
Sleet, embedded in the dam 170
Surface
3
48.53
44.56
30.96
30.96
159.0
130.9
71.0
Francis
3 X 14.6
67.2
73.9
2
Oil immersed seif cooling
Number
VoltagcfKV)
Lcngthfkm)
I
132 165
534. POWER SYSTEM STUDIES
44 Background
I.
V’          ■
4.1.1  EELPA'a Interconnected System
'fc.t
.,■1■
Electric Power Supply  in Ethiopia  ia  provided by  hvo  separate systems namely  the Self - Contained Systems (SCS) and the Interconnected system (ICS).  The SCS mainly  comprises local diesel generating systems which are gradually  being  replaced by  connecting  the systems to  the ICS.  Some of the SCS station*  in the Bahar Dar /Gender area has been interconnected to develop a regional ICS. Very soon this
Regional ICS shall be connected to the main ICS.
Generation in the SCS consists of small diesel units of which 16.94 MW of installed capacity is operational and 8.77 MW is standby. Three small Hydro plants also contribute 5.71 MW of installed capacity to the
SCS.
Major portion of power generation,  tran-smisrion and distribution facilities in the country  »  undertaken by  the ICS,  The annual load
f,
’ ” ’
■
.1 ' T1’ ■ 1 ' a.;   ■ j
factor in the main ICS is presently 60% which is indicative of a modest industrial load,  in addition to  the commercial,  lighting  and domestic demand.  There is no  distinct seasonal variations in either monthly energy  generation or peak power requirement.  ICS generation for 1994/95 was 1319 Gwh with a peak load of 280 MW.
The main ICS capability at present (1995) and for comnuttcd future plants is summarized in table 4.1. The total firm energy capability of the main ICS is presently 1607.5 Gwh/yr with a dependable capacity
of 351.5 MW.
L
This capability u provided from five hydroelectric
r. :
I
-a
* *7
54
fa
■V, -
!■■■power plain namely  Keil,  Awash 11,  Awash til Fmcha  aid Mdka Wakens In (he ongoing dcveiopnwnl of (he ICS, three committed (or planned) projects are:
ihcmial pSanl project, 60 MW capacity to bo insulted in three phases starting  from year 1997.  The thermal units shall be installed at different hnad control of the main JOS.
Geothermal project, 35 MW instilied capacity of which 5 MW is to be installed in 1997, 15 MW in 2000 and another 15 MW fn 2001.
. " j- - ■ >■ 'r f ' 
■.
■                '■
“-a-L " ■:
", ■ .           ■ ■
'.
-■     :■ .■:-
. ■■ ;.t:
GilgclGEbfl Hydroelectric project, 1&0 MW installed capacity of which
.
90 MW is scheduled for completion in 2000 during the first stage of
development and the remaining 90 MW tn 2002.
' ■”       ■
5^“"
■      _-r . F 
l-
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S-fTable 4.1 ICS CAPACITY AND ENERGY CAPABILITY
CapacityfMW) Energy
(GWh\yr)
Year
Station
Installs
d
Depend*
ble
Average            Firm
A         PRESENT ICS FLANT CAPABILITY
1995
Koka
Awashll
Awishlll
Finchai
Melka Wakena
43.2
32.0
32.0
!00.0
153.0
34.5
32.0
32.0
100.0
153.0
134.6
136 6
1363
6253
5813
Sub total (1995)
M02
351.5
1614.1
16075
l"
u.
r
. !-
B          DEVELOPMENT OF ICS CAPABILITY TO 2002
'' _ i- s
19%
3.84              73.7
1997
Tia Abay
Thermal 1" stage
Geothermal
Char -Chara
115
27,0
5 JO
27.0
5.0
7.66
142.0 323 100.74
1998
1999
2000
2001
2002
Thermal 2  stage
-
12,0                63.0
Thermal 3  stage
-
Geothermal G.Gibe 1st Geothermal G.Gibe 2nd.
12.0 21 JO
15.0
90.0
15.0
90.0
21.0
15.0
90.0
15.0
110,0
973
397.6
973
Total 2002
UM
90.0               397,6
638.0 308624 3051.44
564.1.2 Supply Demand Baliace tn lhe IC£
At present the peak demand of die ICS is 230  MW  while the
dependable capacity of the system is 351.5 MW, By 1998 this capacity
will grow to 4015 MW after the addition of Tis Abay (+ chara chan
development) and 39 MW diesel generators to the system. But in this
year there shall be a deficit of 262 MW in the system (we table 42),
Similar problem exists in 1999  with the addition of'2j MW  to  the
system while the power demand grows un-proportionally. The deficit
here is 46.1 MW. The power shortage prohlem will not occur in 2000
■ " ■
= C_,= "           ’
, 
.. -in. .   ■
with the coming of G.Uibc I * Stage (90 MW) and geolharnHl (15 MW) to  the syitcm but still a  deficit of 5,4  MW  will occur in 2001.  The addition of O.Gibc 2nd stage (90 MW) will Etop the power shortage problem fw a couple of years (2002 A 2003).
Unless a new power plant comes to the system the shortage of power
will sun again in 2004. This year may be considered as the right time
to bring the medium hydro plants to the ICS since nine years time is
so sufficient ip bring a medium hydro plant to service.
The Abbay project i s considered for generation supply to the main ICS. Among  the three sites selected for this project Abbky20 should first be developed then Abbay-21  coma  next followed by  Abbay.22  (the development is considered to be cascaded). This is true only if all the proposed *ila  are promising  with respect to  geology  and civil, otherwise the development sequence may change.Table 42            Main ICS Power - Generation Supply Demand Balance (1995 - 2005)
Analysis on Dependable Capacity Basis
Yttr
AdcUtioatl HPP
....... -
Generation
Capacity (MU')
Installed
Depend
Load
Demand (MU')
StlrplurM
W)
1995
360.2
351J
288.6
62.9
1996
■-■ jb'r ■
Tii Abay
371.7
35534
319,6
35.74
1997
Chara - Chara. + A.Langano +
therm. 1“
5.
-l--r ,
r
403.7
395.0
382.4
12.6
1998
Them 2“
415.7
407.0
433.2
-261
1999
Therm 3rd
436.7
428
474.1
-46.1
2000
G.Gibc I  +
-
Geothermal
541.7
533
515.8
17,2
2001
Geothermal
556.7
548
553.4
-5.4
2002
G.Gtbe 2nd
645.7
638
5921
45.8
2003
646,7
638
629.9
8,6
2004
647,7
638
670.4
-32.4
2005
646.7
638
714.0
-76,0Since the coraniisiotiing dates of the above mentkxwd power plants may not be so precise, the supply-demand relationship may probably change. And the negative surplus figures indicated io table 4-2 {years 1998,1999 & 2001) may not occur if the power plants in service year happens to come earlier than predicted. Instead the shortage which starts in 2004 may shift to 2002.
r -./
4 J      Power and Enemy CapablBty of Ahbay ProJe^S
The ultimate Firm energy development of the throe sites m the abbay basin is 187 GWh/yr and instilled capacity of 109.0 MW. Table 43 shows the power and energy capabilities of each site. The potential development may probably
* m
change,  as other possible uses of water in the basins arc considered.  To minimize initial costs and thereby facilitate financing, the development may take place in stages.
Table 43 Powes and Energy Capabilities of the Abbey Development
Development
Finn
Energy
(GWltyr)
capacity
(MW)
Firm
Power
(MW)
Abbay-20
472
29.8
222
Abbay-21
68.8
36
30.7
Abtay-22
+
71.0
432
31.0
594-3 Mechanical Equipment and Servicer
0,1 CenrraJ
F<x all the plants a trash rack, a sliding guard gate and a wheel mounted service gate is envisaged al the Intake.  A sliding  and wheel mounted gates would be installed at the bottom outlet for desilting the reservoir. The gales will he capable of closing  under maximum flow conditions and will be designal for the maximum heads.  The operating  mechanisms of these gates and trash racks could be housed in the same structure if a combined bottom outlet and intake structure is adopted. If a separate bottom outlet and intake is chosen,  independent operating  structures will be used.  In both cases,  the operating structures will be located al the crest of the dam.
For all the plants, the penstock conveying the water will be a steel welded eoostructiun which will be embedded in die dun body. The penstock will be designed such that it would be able to resist the water Bimmer effects since surge chamber could not be racotpuraled in this type of power plant
The power house will be an indoor, The machine hall will be provided with ample space, for erection and service bay, which will become handy during the time of servicing and maintauui.ee.
The generator! and electrical control equipment are set above the estimated maximum tail water levels and arc not subject to  flooding,  AD control, ntetaing  and protection panels are to  be located inside a  control room at generator floor elevation or higher, depending on the final power house layout
■
A
■*
604J 2 
r
Eqntoinegt
4 J J-1             Turbina
1■
Fnncu type of turbines with vertical siutl ta  found to  be the most appropriaie for the three power plants. Rated ocndidOd of (he lurbina fw AB-20,  AB-21  and AB-22  power plsnts are respectively  the follow ihg:-
Rjled heads 73.0, 70.5 Sc 73 9 a Rated flow 46,1, 619 4 672 nflS Rated output 29338.9 & 44.56 MW
unit  floc  maintenance  purposes.  The  valves  will  be  designed  for  the maximum heads.
434 J                P^harae pit Cite
A single gale will he provided for the closure of the turbine d pit, A monorail hoiit wiU be .suitable for htndlLnjj fh? gate*.
.- ■
61Power bouse crane
A power house crane will be provided to handle the major equipment in the power house, including generator rotor, inlet valve and turbine runner. It will be an electric, overhead travelling crane,
dJJ.4 Mechankjl Services
■1
.   ■ ' » II ■ '
r ;    '
■ ■ ■ ■ '
-1
The different mechanical services that has to be included in the power
houses of the three plants could be,
a)          Unit drainage and piezometer  piping
i '       ■          ■
.
■     1 " 
b)         Cooling water pumps
c)         valve pit drainage pump
d) Ventilation system, comprising exhaust fans and intake
louviw
c) Venting and air conditioning equipment
fj Compressed air system for generator brakes, turbine
grease pump and service ouileta.
.       HV '  - . t't* >iB
g)
Oil purification and handling for oil Tor transformer,
generator, turbine bearings and governor,
h)
Service water and potable water system
i)
Sanitary sewers treatment arxl disposal system
j)
Standby power supply for station service
k)
Fire protection equipment etc.
62
<4.4 Electrical Equipment and Senjgg
j '«'* '
„ 
?          »■ ' .< r
a-
4.4J Gencralor
The generator selected is a amvenMttai vertical. 3 phase synchronous with a brushless excitation or a thyristor excitation system. It will be equipped with enclosed type cubicles composed of a circuit breaker, a surge absorber for protection igainst surges from the Line inside; the station service transformer and instrument transformer for metering and protection.  The insulation duaificatioo  will be class F  with temperature rise of I00*c on doc stator and rotor.
Cooling method for the generator will be air to vater heat exchangers incorporated within the generator enclosure.
The main characteristics of the units will bet
Development
Site
Abbay-20
Abbay'2!
Abbay-22
Power output, MVA
160
20.0
16.0
Power factor
0.9
0.9
0.9
Out pul voltage, KV
10.5
10 J
10.5
No. Of units
20
2.0
10
Speed .RPM
300.0
300.0
300.0
No. Of poles
20.0
20.0
20.0
The generators shall directly be coupled to the turbine. For ease of assembly and disassembly during maintenance the rotor u provided u one piece.
63] ] }
1
] ] 1
I
I
I
4A2 Mato power trtnifonner
Each generator unit is provided with a  1- phase 3  winding  outdoor power transformer, oil iramcrad self-cooling type conservator. The transformer shall b* equipped with ■. circuit breaker. * line switch, a lighting arrester and an instrument uansformcr
Trafisfotzncr characteristics are:
... . ■
“■ ■          »    ' ■" 7             ■      ’ ■’ r.r- J .       ..->’7 - - -
■
Abbiy 20 Ab bay-21                 Abbay-22 Capaoity.MVA            16/16/6 20/20/6              16/16/6 Voltage, Kv             103/132/15 103/132/15         103/132/15
<"    ■       r
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4.43 Station       Service Power
.
I
During unit operation, power to the station auxiliary equipment will be
supplied frail the unit station service transformers, For unit start - up and shut
down. unit stand by or emergency operation, power will be available from a
diesel generator (or through the supply from the 66 KV transmissioc line and
the  tertiary  winding  of  the  auto-transfwwcr  in  case  of  Abbay  20).  Power
supply to the intakes and nearby town sites or housing areas, could be from the tertiary winding of the main transformer ( or Autotransformer in ease of
Abbay 20).
4A4 Trmmibtkm lint
44.4.1 Abba? 20
The 132 KV transmission line, coming off the twitch yard, shall terminate at Combofcha I32s66 KV substation. The length
64
ji_J.
f*
f-
■ I ■ I J 
,
p
involved is [20 km. To provide pawn for construction t 66
KV line may be constructed early during the construct™ phase from lhe power house location ICf interewiDect with (he 66 KV lint; al Laiibtla (see fig. 19).
4JAJ Abbeys I-and Abb*)^
:Y
;■/ I wk"
i
-
r.
The 132 kv Iran Emission line corning du i of Abbay-2i and
Abbay’22 substations shall terminate at Abbay-20 and Abbay-
21, 132 kv bus bars respectively. power during construction
may  be provided from dtwe line*  if early  constriction is
possible, otherwise diesel generators can be used.
4.4.5    &C_Cojin-pl Power Supply
, .. *>
V ■*
i
£V ■
. J-' i
For reliable control apd equipment protect™ Ind cr nickel cadmium batteries shall be used- Voltage required will be 110  v.  For the opcrjlitHi of wrnnmnicatkras equipment a 48 v de supply system shall be used.  DC power supply  will be charged boro  the auxiliary transformer and from the d5e$ri gemeratw (or the tertiary winding of the aute-traASfornier in Case uf Abbay-20  ) during  cnvrgcncy ertiutiflttL
4.4,6 Grauudlne Syiiem
For personnel safety and to ensure the survival of equipment during fault ocomtejice,  the generating  slatioo  shall have a  low resistance connection to the ground min, Frames and eackwct of marhin^y
:J '. .. ' ■' *1 i
«■I .
■ ■.
■ <¥ ■ .r*
and electrical equipment shall be connected to  the station ground through secure network of tow - resistance conductor (bare stranded copper and coppcr-platcd strtl ground, rods).
Ibe neutral pcinLs of lie step ■ up power transformers of the station shall be connected solidly to the station ground.
4.4.7 [Jghtjni
illumination while the vicinity of the rotating machinery, gauge panels
4.4JJ Control Pane*
1 1 1.1.
In order to  increase reliability,  rationalize maintenance reduce cable length between control equipment,  minimize installation space and shorten the installation period and integrated digital control panel shall be used.  Speed regulation and excitation control u well u automatic synchronization are built into a tingle processor. To increase reliability further the circuitry for protection devices is built independent of that of control devices,
r
’ 66i
■
■ ■ /.
43 Tranmlssipa Syitta AA*hjh
431      TrinimBsfon Sytltm Planning Principle*
p  » ..-tX'C fc
4AL1
General Principles
I
In general the new system has been planned in such away;
fe-
& ..
fc
<
1.
Thai  there  ia  suffident  transmission  capacity  at  each  voltage
level to transmit power from the power plants to the distribution
network
•** '
A..
■■_.
1
3.
--
■ Jj
That suitable voltage levcla are selected fw power transmission and acceptable voltage profile is maintained in the whole
system.
&
a ■
4.
That the generation can be dispatched m an optimal w»yr
5.
That u optimum economic result £a reached taking into account
investment^ operational cost, coat of lone* and reliability,
6,
Ttul short circuit level docs not exceed the equipment ratings.
7+
Thai faults result in only  small oscillations with sufficient
damping.
J
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-
4
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67
1 I
4 * 4 >
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At  this  reconnaissance  the  first  five  principles  bivc  been  applied properly.
■  ■      ■     .           c■
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*
4.5.12 Technical Criteria
The  main  points  of  the  technical  criteria  considered  are  u folio WK
- Ths voltage at any point in the transmission system
■ 1 ■" •• 
■ ■ ';
shall not exceed the highest operational voltage allowed for the voltage level of concern (105% tn thia case), the voltage shall not be fowff than 95%  of the nominal voltage of the voltage level.
A    15%    overloading    capability    is    allowed    for transmission lines and transformers during peak houn.
4-54 J              Approach
l' 1 U
I" •
■?
,
The  situation  selected  fat  study  is  year  20M,  when  the  fait medium hydro-plant assumes to appear in the system.
The Peak - Load was taken as 90% of substation peak demand and low load wu considered as 40% of peak had,
4-52 Result of the l jsd Flow Analysis
The power flow analysis carried out to  envestigate foe effect of mtrodiKting Abbay to the existing system of EELPA has revealed the following facts;
<58The voltage profile of foe long  cabbie - wmbokha  lineh which frequently  encountrei under vnltagr problem,  has been improved (see annex 4).
As the location of Abbay  is near to  foe northern area  where power is to be delivered from a long 130 tv transmission line, the presence of Abbay has improved the system perfarman« of that area.
No  reinforcement is required st comboich*  substation as the
'
I  - ’... 
. jZi ■ ■ ’ J ■ i.,. '.-it ■’ f ”■     ■■■' 1.
existing equipment can lately carry foe additional. power
coming from Abbiy. What is required will be the incoming line bay for foe 132 tv line wmlng off foe abbay twtidi yard.
- Ji -      '
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69
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5, IMTIAL ENVIRONMENTAL ASSESSMENT
5.1 Background
11.1 Purpose and ObjtctivH of Stndy
The primary purpose of this study is to select a medruin hydro project that might be considered as alternative hydro  electric development schemes on the Bcsbiki River. The Reconnaissance will determine, in
a preliminary manner, the tnvirunmcntaJ and conditions of the study area  and  die  possible  effects  of  die  hydropower  projects  oo  the environment. This will help ensure adequate and timely consideration of  environmental  issues  in planning and development of hydropower projects on the Beshilo River.
The  primary  objectives  of  the  Environmental  Reconnaissance  are  as
follows:
a)         To obtain information on and describe the existing natural and human resources of the study areas
b)         To indicate potential environmental effects
c)         Tp stale genera] requirements for further environmental studies
5.12 Scope
The reconnaissance study serves u a "scoping mechanisin'’, that is, the work help* to determine which environmental effects art most
70pronounced and require foriher study.  Il highlight potential constraints of proposed devebpo^b,  and mridoi the nsrita  of alternative dam sites.
The rswnaissancc level study  rdiw primarily  on existing  information and data  sources.  A Limited field survey  program™  and interview! with experts and local resident*  supplement these existing  sources of date.  Work waa  conducted at an overview level in order to  make best use of existing  infonnation and permit appropriate planning  to  be carried out for subsequent phases of study,
5.1 J Content! .gfJteMrt
.A
■
.■.■r ■ ”' ■>! * Jl_TL ■
following  the
introduct
ory  text, 
secti
on
5.2  of  this
report  provides  a
summary   des
cription, 
dwelling 
cm
det
ails   of   the
design   which   has
implications ro the potential .environmental impact of the Ekshilo
MHPP,   The   existing   environment   is   discussed   fn   section   jj   and section 5.4 desk with the predicted inipicti of the project Evaluation
Of projects is presented in sect™ 5.5.
54 Description of the prupoiwl Project
Medium Hydropower projects at three locations on Lesh ib river were studied and comparative evaluation prepared of the main features of the various dam Locatifln and ma  of development The environmental npconruLsSince WOak it under taken m this studies «o  that the findings can later be applied to  a comparative CviiuatbMi of fhc Virion* dam locations and sires of dcvcLopmetiL The following  three alternative baied cu WAPCOS recommendations were studied.
715J.I Abbay-20
Alternative Abbay-20  is located in Delanta  andTcnta  wcreda  of Region 3,  north of Addis Ababa,  The altitude of the proposed project area  is between 1545  and 1626  msl.  The project site can,  be reached by proceeding on Addis - Dcssic road and turning to the left about before reaching Dessie town. The general cbiractenstiM of the dam are
indicated in Table 5.1.
1 
J-.--"-'
> '           ■
+”
■
u-~TL “
>
-
c
Table 5.1           General Characteristics of Abba.y-20
A
Dam Type
■j- .        ■ Concrete faced Rockfi11
Dam Height (m)
85
Full supply Level (ra)
1626
Minimum Supply Level (m)
1606
Approximate Reservoir Area at FSL (Km )
1
83
Total Rcscrvoir/Volmne (10* mJ)
511
Effective Reservoir Volume (10* m )
1
165.6
Annual Electric output(Gwh/yr)
863] 1
] ] )
SJJ Att.v-21
Thil alternative is also situated on Beshilo River and is located in Masha and Dawnt Wcroda, of Region 3. The altitude of the proposal projet! area is between 1444) and 1520 msl. The Table below depictj the general characteristics of (he dam.
Table 53 General Characteristics of Abbay-21
Dam Type
Concrete Gravity
Dim Hctp.hl (m)
80
Full Supply Level (m)
1520
Minimum Supply Level (nt)
1406
Approximate Reservoir area al FSL
(km )
1633
1
Total Reservoir Volume (I0W)
982
Effective Reservoir Volume (LO* ini’)
354
Annual Electric output (GWH)
118
533 AbblY-12
Abbay-22 is an alternative to Abbay-20 and Abbay-21 is located in Masha and Tech Gain Wereda, of Region 3. The altitude of the proposed project area is between B50  and 1430  mri.  Table 53  below shows the general diaractcrij&M of the proposed project
73■
J.
.‘r y'     1 ‘ •
Title 53 General character! str ca of Abbay-22
Dun Type
Concrete Gravity
Dam Highl (mJ
85
Full Supply Level (m)
1430
Minimum Supply Level (mJ
1406
Approximate Reservoir tnt at FSL
fl™ )
»■-
1
1033
Total Reservoir Volume (IQ  n?)
4
562
Effective Reservoir Volume (I0W)
1          ' -l’            ■ AT i " ■'K,             — Tfc' ' ■
4
241
-
Annual Electric output (GWH)
130
■*■
■J J, 'J
■. •*
■r
/
I
S3 Dwriptfcu or the Eibling Enyirommeat
53.1      For_eX Resources
L-i
!, * ...
1
'i I
The proposed reservoir areas will not inundate i dense evagreen W primary  forest lands but tn isolated trees arc found on the left and ri^ht bank of lhe river.  Much of the secondary  forest within foil reservoir area  has been altered by  human activities such M agriculture firewood and forest foes.
53,2 Wildlife
A relatively  small [Lumbcf of wildlife species still exists fo  the proposed reservoir rites.  Many  of these animaU make demand on natural habits: and the river wafer.
J - " t • ■ ■ ■ / ’
B
■ .7::"- ■
74533       Aquatic ReiourgM
There is no  available background information regarding  the aquatic ecology  and fisheries potential of the sludy  aren.  However,  based uh lhe field visit and information obtained from the local residents,  the project areas do  not support economically  viable aquatic life like fish and none of these reservoir sites are fishing areas fee local residents,
534       Archaeological. Religious and Historical rite*
J ■.
/. . ■/ ■■■
■            ..
"Ja
■
'
‘i'
"'
No   major   archaeological   or   historical   sites   of   may   significance   are known io exist within the proposed, areas.
None of the relig>pui places and/or burial grounds visited by the people oirraiily rt-SHimg in the area surrounding, the proposed rewvoir sites
. ■''■■■ - ■ ■ ■
arc located in areas that would be inundated by the proposed project.
533 Public Htaitfe Statu*
The reconnaissance work enabled the collection of information concerning  public health conditions within the study  area.  The public health survey  indicates that the general health status of the population currently  residing  in the ana  surrounding  the proposed reservoirs is very  pew.  Review of available information and visit to  the project area revealed that the major health problems relate to  infection*  diseases propagated due to  Lack of ufc water supply,  lack of buic unitati™ and personal hygiene a» well as poverty.
755J 
of Potential Environment*! Im cacti
The proposed medium hydropower projects on the Beshiio  River wilJ  hive positive and negative effect*. Environmental impacts can occur during both the consiruction and operational phases of the project The main souruea of effects for both phases of the proposed project are identified and major findings of the assessment are summarized as fbttowt'
54.1 Positive Environmental Impacts
The  specific  positive  impacts  of  the  Rcshife  MHP  Project  common  to each of the reservoir projects are briefly described below,
5.4.1 J             Fkctrfctty Generation
The main benefit of the project will be its ability  to  generate electricity.  The planned project will be a  medium Hydropower stations The generating  capacity  of the proposed project*  arc indicated in Table 5.1,  52,  and 53  above. With such electricity generating  capacity,  the project will be highly  useful to  the Nation in curbing the growing power shortage. In addition, the project will tremendously  benefit by  cutting  the expensive imported hydrocarbon fuel,
54,12                 Flood Protection
The   implementation   of   the   project   will   contribute   for   the reduction of frequency and extent of downstream flooding.M.IJ                   Employment
The project will generate both short and tong  term employment opportunities during  the construction and operation phase of the project
5AM                   Wildlife and Birds
.' f ■ ■ t I-1-' ■
\
r  ',' ■ . -
A  positive  impacts  by  attracting  wildlife  and  birds  is  expected as the result of the creation of the reservoir.
■                            V                  ii + 4             ■
■ 'fc
M.U                   Other Benefits
.1
_»■
i
It is true that construction of the proposed reservoirs will inundate productive land.  But it is equally  true that the proposed hydropower project will boost economic; development in the region as well as the Nat™.  Over the years,  due to  many reason*,  both the urban and rural economy  tn the Region has developed very slowly, The local standard of Living is still quite
low.  The area's economic infrastructure ia  poor.  If the project is tamed out,  investment will increase and this will promote agricultural,  and industrial,  as well «*  urban construction.  The reservoir system i*  expected to  provide ideal conditions for fish to grow and breed.
J
-lb
.     ,      ■
77S.<2 Potential Negative Environmental lap*d*
The major environmental impacts of the proposed BahOo mcdhitn Hydropower project are discussed below.
5.42 J                 ■Social Impsct*
Vosges and a town in and around the proposed reservoir arena were  surveyed.  According  to  the  study  which  set
... 3 -
the  Abbay-
' ' ,T“ ’’■'fir' '
20,21 and Abbay-22 resexvpin water level at 1626,1520 and
1430    hm!     respectively,    no    village*    will    be    affected    by construction, of the dun and emtioo of the reservoir. However,
the project will have effect* on tuc population rending along
the BeshHo river.
The number of households and population that would be affected by the construction of these reservoir*, at different levels of inundation is not known. Major anticipated effects of the proposed project* include the displacement of residents from their agricultural land. A dominant proportion of the population belong to a single ethnic group called Amhara Farming and agriculture related activities are the primary occupation of the residents. The displacement of these people from their fertile river side agricultural land is the important environmental and socio-economic issues of the proposed hydropowa' project* at Abbay.20^1 and 22.
785,42.2
5h42J 
S 41  4
'-
of AgrkpJflnre_hnd
The main means of livelihood of (he population in and amuod the project area  arc farming  and cattle raising.  The creatwn of k reservoir Al all sites,  will entail loss of Agricultural land, farmers comprise the majority  of the waiting  population who spend much of their lives cultivating  agricultural land located within the proposed reservoir area.  As the result of the loss of agriculture land,  the primary  occupation of the residents will be affected.  The lifestyle of the people will also  be affected by altering  economic activities and socio- demographic conditions in the area.  If relocated,  inhabitants will be subject to  a  period of social readjustment
Loti of Grazing Land
The project areas are also subject to grazing during all season. Undoubtedly, the inundation of grazing land will affect all
farmers in the nearby Peasant Associations who are using this
grazing land- The proposed project would therefore, result
directly or indirectly in substantial changes to the arviromnaital conditions of the dry and wet season grazing lands.
Effects on famti
Although there are no  primary  and evcrgreoi forest areas in the project areas,  because much of the trees has already  been
extensively   disturbed   by   human   activities.   Abbay-20,21   md   22
reservoirs  will  inundate  isolated  trees  and  result  in  very  little forgone opportunity.
79$A1£                Effects on ycgetitfon and wildlife
The   project   will   not   have   significant   effects   on   (he   wildHfe, wildlife habitat and vegetation of the study area-
SAI.6                Effects on Aquatic Resources
Experience gained from other hydropower projects indicates that dam construction and reservoir operauon will have significant effect oo  aquatic resources.  The complexity  of aquatic systems and lack of suitable data  of resources in the study  area  make it difficult io  predict (he aquatic impacts associated with the proposed projects.  Some general observations,  however,  can be made regarding  (he potential consequences of the proposed hydropower projects.  Anticipated aquatic impacts would likely include the following:
Spread of aquatic weeds.
Alteration of the hydrologic region of the rivers,  i.e. replacement of riverine environment with a  alowcr moving  body  of water upstream of the dam This will, in turn,  offset water quality  and the composition and abundance of plankton.
Changes in chemistry  of mater due to  lower dissolved oxygen or raised nutrient levels which would destroy aquatic biota  and place additional stress on surviving
specie*,
80Release of toxic substances (e g  methane,  hydrogen sulphide,  ammonia,  organic and metals) stored m sediments,  which originates from disturbed and newly flood Wil.
Anaerobic     decomposition     of     submerged     vegetation within the reservoir arras.
Creation  of  an  impoundufcrit,  which  would  provide  the opportunity for establishment of a reservoir fishery.
5.4,2.7               Impact on Public Heatlh
Development of water resources in tropical countries potentially means a  change in the incidence of water *  borne diseases.  The construction of a  dam and the creation of an impoundment can alter ecological conditions which can result in beneficial or harmful effects on public health.
A   review   of   the   health   situation   in   the   area   indicates   that malaria  is  the  primary  health  threat  The  change  in  breeding habitat   as   a   result   of   creation   of   a   reservoir   may   increase significantly  the  abundance,  population  density  and  distribution or  mosquito  vectors  which  in  turn  would  increase  the  likelihood of malaria cases.
8154 ^valuation. of Projgtt
54.1 Coin punitive Evaluation Matrix
The previous sections of this report provided * review of the finding* Qfgajiizcd by disciplines (such as land use. forest resources, aquatic resources, etc.} in accordance with the methods of investigator, adopted for the reconnaissance study. In additions, under each study Subject, the findings have been reported for each of the hydropower projects examined.
In this section,  the study  results are presented by  project and environmental subject in the form of comparative evaluation matrix (Table 5.1) The factors that are evaluated in the matrix  represent significant environmental considerations, impacts associated with the proposed hydropower projects. On the horizontal axis, the matrix cell values compare qualitative interpretations of effects.  18  factors are evaluated and reported in this way,
The matrix  suranurwes the study  findings in a  format that allows ranking of projects in terms of their environmental effects. The ranking is presented along  the bottom row of the evaluation ma  trit This ranking figures are comparative, that is to say, it is a relative ranking of the three options which have been examined. A ranking value of one is assigned io  the 'most preferred1 project option from an environmental view point, while « value of three is assigned to the
82least prufenett' option Options were ranked against each other,  and not against other projects ouUidc the scope of this study.  This matrix identifies resources that tray  be significantly  affected so  that subsequent assessment may  be more finely  focused and made more efficient.Table 5.1 Comparative Evaluation matrix
Hydropower Proi*^
AJbbay-20
AWxy-:i
Abbay 22
Opm®*
FSL (m nuJ)
Dun lUgbl fm)
Mean wuwaU nwr Flaw {■ M)
1 we
90
2X1
IS20
15
SI
HM
S3
m
R-cwovir Vohnn*
Tcul ruervuiT wCume ILS^in'j
Actn« HCAjt 410^ n> >
h
I3t*3 EinrayF C10^* 5n l
¥
Sil
165
M*
554
618
562
24IJ
320.7
Ro^rvotf «■
1
A1 FSL (Ka )
1
A1 D**J Borage kwl [Ka )
xs
542
1423
M.77
1033
5.43
InAallcd capuUty (W|
29JJ1
M.9
44, %
Abem4 <I*Ak output (GwWyr)
«U
11*
i»
CSeeefMbt^ ura - art (US ohmaIWH)
r
M3
31.4
17.67
Total C-ltu
nu
ITJ.9
275
Acnu- Road
Length ;Wi
IIS
| IB
170
L-ttd ltt*
ToUl lud li'ailiii flta)
Apiculture Lud inuikluod
f&resL liijtS umndhlfd
CrfraA±g Land miindtfwi
850
high
HEjJI
Kxull
1623
high
IuIaI!
nnmll
1033
W«-
KnaO
miUCorfd Tibta 5.1
HydmpowCT PT7>J«n
Abh*y-i}
Abhay-21
Abb*y 22
Ftora iod bnju
Utt WHl ipowH.
Wildlife i*hlM RJbOM*
tetarrtka ra PWofiiil
■
■
FWTTWi
am
□one
DCM
KCC
A 4u*i k rmwu»
FjbascJ ^pcua
Fw&zKa hibftH
Aqubc Mdi
NA
NA
ya
KA
NA
yu
KA
KA
Viltaen
N-jnhn «T AJbcled VtUija
mfruEUd&rv                     efJwa
elm
z
Pc^ulaix*
Alro-ind PvpulahQti
AfTeoad Hiwtjckk
Phml4 of ahrik miDoriiit*
-
KM
PuhU IWlh
Health hifrisniXj^ Effect*
hftn Heaftt Klaki
torwR
OodcUa
Arc2jn.:kTO
JLd*x«u| um
M(jd* tilt!
□WK
□OQfi
OctiJ Kuiuofl
AS  be   rwwirtHTi arwnnjHiiri p
1 to ta «p*lly
MM trf MWW
decftblfl fnxn
853.5,2 Congluifoni bawd on [be evaluation jnitrir
The remits of the evaluation show that within the framework of the three project optical or cases,  ill are considered Co  tx  equally desirablG from environmental point of view.6. SOCIO-ECONOMIC ASSESSMENT
6.1 Background
The developmeni of a  river basin for any  economic or social use entails a  lot of social and environmental problems.  These problems which crop up during the development stage and operation period,  should be assessed well in advance when the different project Studies Lc.  reconnaissance prefeasibility,  feasibility and design arc carried out by  the responsible development agency.  The identification and assessment of these issues will solve the problems that may arise at a later stage and will enable to design mitigating measures.
Some of the problems that may  arise arc the inundatkru of farm land, grazing area,  residential houses,  destruction of archacological remains,  historical places, social relationships etc.  and the resultant impacts and effects oo  the communities which arc in most cases not the direct beneficiaries of tile project.
6J Methodology
Td identify the social impacts and consequences of the projects, the
sociological survey aimed at collecting data from primary and secondary
sources. The primary sources of information are the people who are directly
or indirectly affected positively or negatively by the project The information
were collected through discussions with the residents and local officials at
different levels. The secondary source of information ire written reports both published and unpublished by different government and other institutions.
For this specific survey, rite visits, though for some of them for a short period of time,  were made at the different proposed dam rites and discussions were held with residents and focal Government
S7officials.  From the site visits it was possible to  acquire first hand information on die social setting  of the population and the likely  impacts and consequences of the project
Admtoblrative Division
The Administrative structure of the country  is based on Proclamation No.  7  of 1992  that provided for the establishment of National ly/Regkmal Self - Governments.  The country  is divided into  14  Regions and Abbay-20,  21  and 22 proposed dam sites fall in Region 3 (Amara Region).
The wareda  is the basic administrative hierarchy  of any  National/ Regional self Governments keeping  the Administrative hierarchy  of Kcbte in rural areas as well as kcbeles and Highers in urban centres as they are:
The Warsis Administration has the following organs.
1.           Wonsda Council
2.           Worcda Executive Comminee
3.       Woreda Judical Organ
4.           Woreda Public Prosecution office
5                Worcde Audit and Control Office
ti. 
Woreda Security and Police Force Office Woreda Services and Development Office
I snd Holding System In WqUq
The  rural  land  holding  policy  in  the  country  is  the  same  alt  over  the  country. Rural land belongs to the people and the Government This hu been assuredby proclamation No.3 of 1975 which altered the feudal agrarian relations in Elhiopia. The proclamation prohibits private ownership of land by individual! cr organ rations aa well a! the transfer of land by wl^* Lease* mortgage , <* any  other means.  However*  the Economic Policy  of the Transitional Government of Ethiopia has provided the opportunity foe private enterprise to rent land from Regional Governments for any  kind of development.  The present situation in the rural areas is that the Kfibdc peasant Association distributes land to the fanners and any dispute is settled by the kebele council. State forests,  reserve area! and farms are owned and adminuleitd by Government Institutions.
Demogaphk Data
The available population figures by the Central Statistical Authority (CSA) follow! the old Administrative Division of the country since rhe outcome of the recent census figures are not released. The population data according, to the new Administrative Division could be obtained when the 1994  Census tesult! are ready and available for distribution, For the purpose of this report the recent available information is taken from CSA documents.
The total population of Wako  Administrative Region according  to  1995 estimate is 4*339,200 out of which 464300 is urban and the rest 3*®74*9M is rural ■ The demographic data  on major town population,  ethnic group, religion, language, health facilities,school attendance, and economically active population by major occupational groups of both turd and urban are presented in the following tables.Tabic 43.1 MijorTowm Hud Petition, 1992’
r
Awr*J*
WuL^
Hath
Sduli
EkiLiki*
Auyu Dute
Mdk
Mtkue 5ctau
Seyv Wqpd*
K4d»
Ajibv Kuuh*r
De^ KjJdx^h
Bid
Bara KrJTljM:
Andhra
Hirbu Kambokhi
LAth
tno
T31J
ms
1544
W?
1628
10115
6»l
IM90
455
ion
im
134
ITS
4490
MM
1W
2M*
WH
WM
2698
1M5
TO
14S4S
875
6*53
<W
1481
mu
MMpLtinut-s
i
IT* W1Tabic 6.51 Perccnta®e Distributor. of the population by Major Ethinic Groups, Wrllo, 1984 *
Ni
Mifw Uimk (jvUJ
1
3
3
4
5
4
I7
1
9
Aajn
*JHr
Afar
Anphi
Olw
Tipr*^
Tipv
CXim
N«1 SlM*d
?Ml
71.6
43
4.7
CL4
f.7
IJ
01
di
XI
1004
rod Houjttg CflMm, ]$m
91Table 4.5.3 Percentage Diftributwn of the Population by Religious Group*, Wdkii IW
OjuUm
Omhedt*
PnMaUdt
i
Ottm
Tradtimtf RrUpa
Hm 5JM*d
Tout
4Ji
417
1.1
-
55.7
9LI
DJ
LI
tCKI.C
hr-au., ifcMta, c™
93Table   6.5.4   Percentage   Distribution   of   the   Population   by   Major Languages usually spoken at Hofne  Wello 1984.
h
Ml^tr La4p*v
Ai&kHBU
13.4
AfUngnii
4.4
Ajjwjpw
u
ArjFti^M
OJ
()roqup»
w
r.KPHB.
11
Qtan
0.4 
1
Nft SUiad
0.1
Total
lOOlO                                             I
PopuJitoc * J-louang Cawni, 1984
94Table 6,5,5
Medical and Health Ficfliue* of Wctio Region (excluding Police and Armed Force*) 1W/91 ‘
FbcIUt
Nunlw
Hopiial
4
B«h
431
i
ktiaJih £uuau
141
!
Hulifa Con™
11
Suifbai Ahdnc^ 1992
Table 63.6 Population Aged Five Years and over by status of school Attendance and Sex, Wello , 1984,
F
Malc%
Finite %
Tmi X
Atkudinj now
21.7
1U
i93                    :
Aruodod in iht
M
4.S
73
Ancndcd
W.»
7*4
714
Tad
IWA
hjpuiibuo k Hrxaing C««M, IPSA
95J
Tabic 6.5.7
Distribution of Ewnpmwdly Active Population by
Major occupational Groups and Sex., Wcllo, I9B4-*
tknip-U^                                                  Mih %
Fanafe %
TpLd %
ftrafcwMiaJ «d Tcduuckl
u
M
0.6
Aiiiuuuklrxliw &
Oil
'■ 1
■
Ckral & RrlMpi
03
0.1
02
S*ki Wot*
l.l
10
14
Service WorW
0.6
13
1.0
Aumai
riuibisiiy * Fcrrwtry
■M-0
w.v
04.1
ProdurttaMi
wurtwx, Tnfo^cct Opener b=J Libera
2.1
1.0
1.7 
t
Not SUtad
M
T
04
Tcui
iog.ro
HtJpuUteK 4ul                   4>n,..K j yH46.6 Women Development
The statistic*  of th*  country  shown that the women constitute about fifty percent of the tote! population.  This being  the fad.  women stituJ  in all »«*1 and economic spheres lag behind dial of men.
They  lag  behind in education employment,  income etc.  and are involved in dironarablc jobs like prostitution,  house maids etc.  The legal and the religious Lows of both Christians and Muslims favour men and give inferior position to women in general in the daily affairs of society.
In the rural areas they are charged more than men in that part from their home management responsibility they also involve in all activities of farming. 11 is the women who arc responsible for all types of cooking, collecting fire woods, fetching water, milking cows, taking care of children, shopping of house hold needs etc. These activities are time consuming and make, women to work more hours, than men,
It was only after 197 S Resolution that women issues were surfaced than ever before due to the policy of the socialist Government. Women Associations were established at all levels of the administrative structure i,c from Kcbcle to the National although they had their own problems
After the change of Government in 1991 the transitional Government of Ethiopia (TGE) has given due emphasis to women problems and as a result an office has been established in the Prime Minister's office that wilt deal with this specific issue, In addition to this, women Affairs Departments have been established in all Ministries Commission and other National Government Institutions and at the Regional level* with a Bureau Status like other sectors.
97The  biggest  achievement  by  the  TGE  to  deal  with  (his  issue  it  (he  issuance  of National policy on Ethiopian Women. The objectives of the policy are:
1.           Facilitating  conditions  conducive  to  the  speeding  of  equality  between men  and  women  SO  that  women  can  participate  in  the  political  social and   economic   life   of   their   country   on   equal   terms   with   men   and ensuring  Lhat  their  right  to  own  property  ae  well  as  their  other  huntin rights  are  respected  and  that  they  are  not  excluded  from  the  enjoyment of  their  fruits  of  their  labour  or  from  performing  public  function*  and being decision maker*.
2.            Facilitating  the  necessary  condition  where  by  rural  women  can  have access  to  basic  social  services  and  to  ways  and  means  of  lightening their work - toad; and
3.           Eliminating,  step  by  step,  prejudices  a*  well  as  customary  and  other practices  that  are  based  on  the  idea  of  meal  supremacy  and  enabling women   to   hold   public   office   and   to   participate   in   decision   making process at all level*.•
The policy  has strategies for implementation and has also  outlined the responsibilities of the different women Affairs offices from the highest to  the lowest levels.  Theses structures are believed to  enable to  meet the objectives of the policy.
htoocri poUcy M ElfawjM! Womaj, KjUwubo: IWJAJt, ff U , M,
98The bcncfiLi of this hydropower project to women if very significant. Electrical energy  can be used for lighting  Lhe house,  cotiking  food which takes niuch of women's time tn collecting fire wood etc.
The infraslrucmre that will be built as part of the project activities will enable women to  get temporary  and permeant employmenis.  Roads Clinics,  schools etc.  could also  be built which are non - existent now,  These services will benefit women in many aspects.
Social and Economic Aspects of the proposed Dam Site*
6.7.1    Abbey 10
4.7.1.1                Location and Desrripdan
H   is   specifically   located  in  Jita  Michael  and  Wotct  Mariam Kcbeles of Delanu and Tenia woredas respectively.
The river banks are eroded and no  farm lands or settlements near the river which will be endangered if a dam is constructed. The only  farm land that will be flooded is that unlike many rivers the Beshilo  river has a  very  wide sand bed which the people are using  it to  plant bananas,  maize,  onions etc.  by irrigation during the dry season since lhe river flows to one end of lhe banks.  The river course seen to  change every  year due to  silt deposits on the bed of lhe river.  These the so  called irrigated farm lands are flooded every  year during  the rainy
season.6.7.12                 Economic Activity
The economic activities are that of typtCll rural subsistence agriculture like many  areas of Wollo.  The main activities art farming  and catlie raring  which are complementary  to  the survival of rural people.  The main crops grown tn the area  are sorghum,  maize,  tetf,  and other cereals.  The are*  has been hit by drought for many years and seems very severe this year also due to the insufficient rainfall during the last cropping season,
6-7.13                Health
There is no  any  health facility  in the vicinity  of the proposed dam site.  The main health hazard is malaria  since the area  is quite a lowland where malaria attack is very common.
6.7.1,4 Education
The nearest Government schools io  the dam site are located at Yederck Abo  On the Worehimennos side and at Angorgaba Aba Libanos on the Deianta side. There are no people who are sending  their children to  these schools since the consciousness to  sending  children to  Government schools it low and children join their parents trade starting from the early childhood,
IOC6.7.1J                 Communk*tLQD
The proposed dam site is not accessible by  vehicle- The only means of reaching  the site is by  a  helicopter.  Western WoUo is very  mountainous cut by  deep gorges and it is very  difficult to construct access roads.
d.7Jji Ethlnk group lantoaee and reMafra
The dominant ethnic group is Aruhara  and the language spoken is Amarigna.  The main religions are Orthodox  Christian and
Islam.
6-7J Abbay-21
6.7.2.1               Location and Dtscription
It IS specifically located between Diskck Abo and Ycjene
Gorada Rebel® of Mcsha and Dawnt Woredas respectively.
There arc no  human settlements and farm lands near the river banks which could be affected by  any  development on the river. The settlements and farm lands are located on the upper slopes of the valley.  The land near the river banks are used for grazing  though it is very  steep in some places and not suitable for grazing.
The sand bed of the river is used for irrigation plots and are planted bananas,  maize,  onion etc.  These plots are flooded during  the rainy  season since it is on the main river course. The irrigation is done by digging trenches and using buckets.
101652J                 Economic Activity
The  economic  activity  it  similar  to  that  of  Abbay-20.  It  it what people do foe survival that one can see as an economic activity.   There   is   no   any   Gcvenimcnt   assisted   economic activity ihaL is observable in the area. The main crops grown tn the area are, sorghum, maize, tefF, and other cereals. Bananas and cotton arc also grown akmg the nvet banks,
4JJJ
The main health hazard is malaria followed by gastrointestinal infections, In the absence of sanitation and safe water supply these infectious are common in many parts of the country. There is no any health service m the nearby areas, and the only available service is the Usdidonal prac-tioners which is very common all over the country.
6.7,2,4             Education
Then is no  any  Government school in the vicinity  of the proposed dam site. It ii not surprising not to seen any school from the point of view of the physical feature of the area The she ii located in die valley and it it very remote from other settlements.
1026,72^                  ComraujalcJtion
Abbay-21  dam site is not accessible by  vehicle,  The only means of reaching  (he area  is by  a  helicopter.  The physical feature of the area is very mouDtarnoiLS cut by deep gorges and valleys.  It would be very  difficult and testy  to  build access road even if (here is a plan to do so.
6.7J.6                Ethnic gronp, language and Religion
The people who live around die dam site area are Amhanas and their language is Amarigna.  The main religions are Orthodox Christian and Islam.
6.73 Abbiy 11
6.734                  Locatlon and Description
It is specifically located between key Asatta Kola and Indwa
Kebeles of Masha  and Tech Garni woredas respectively,  Since the Beshilo  River is the boundary  between Wollo  and Gender Region, Masha is in Wollo Tach Gaint is in Gender Region.
The dam site area  is very  remote and there are no  settlements and farmlands near the river like the other dam sites.  The residential houses are on the upper slopes of the gorge and will not be affect by  the dam The river bed is very  wide and people plant maize,  bananas,  onions etc.  on (he sand bed by irrigation.  These plants are flooded during  the rainy  season since they are on the main river course.
1036.732
Economic Ai   ■du li
The dam site area  b very  remote and there is no  any Government initiated economic activity,  the only  economic activity  seen is what people do  foe survival,  The main activities art faming  of subsistence level and cattle raring- The crops grown in the area  are Teff,  maize,  sorghum etc.  Cotton is also grown to  some extent The drought b very  serious this year since the rainfall was insufficient during  the previous planting season.  People are seen with their cattle by  the rivet banks who  have come there for grazing  and insearch of waler since there are no  other animal watering  points especially  during  the dry season.
6.7J3 Health
The main health hazard is malaria. There ii no any health
service in the vicinity of the dam site. The nearest health
service is u Nefas Mewcha which is two days walk from the
dam site. Arb Gebeya is the administrative centre for Tech
Gaint Woreda but people mention Nefas mewcha as die nearest town.
6-73.4 Eduction
There is no  any  Government school in the vicinity  of the dam site.  The nearest schools are located at Artigebeya  and Kone which are quite far.  The people do  not seem to  send their children to  schools.  The poverty  of the people b seen from their faces and clothing. Some still dress goats and sheep skin.
IM6.7JJ                 Co ni munkatlon
The dam site area  ts twl accessible by  vehicle.  The only  means of reaching  the site is by  *  helicopter from discussions with the residents a  road has been constructed near the dam site for relief activities some limes ago.  They  remember that trucks come Io  the area  loading  grains to  be distributed to  those who were affected by the drought
6.7Jj6 Ethnk croup, language and Religion
The main ethnic group who  live in the area  art Amaras and. their language is Amarigna,  Regarding  religion,  those who  art on the Gonder side follow Orthodox  Christian and those who live rm the wollo  side follow both Orthodox  Christian and
Islam.
68 Imparls and Effects of the Proposed Projects
The reason behind assessing  the potential social impacts of any  proposed project is that any development effort that changes the ecosystem which human beings are a  pan,  will have a  short term and a  long  term effect on the social selling  and the Socio  - Cultural system of the area.  The social impact assessment attempts id identify  what specific effects can be expected and to recommend means fw mitigating  potentially  adverse changes that may  occur in time.
1056.8,1    Short Term Jmpictl
The impacts of a  river basin development could be positive and negative,  tn ease of Abbay-20.  21  and 22  proposed dam rites one of the moat visible negative impact is that there are crossing  points on she Bwhiki river for the people to  go  to  market places,  churches,  mosques, and other social relations ship flutters.
But if there is any  development an the river the reservoir flf the dams go  for many  kilometres backwards and will be difficult for the people 10  cross from different points a*  they  used to  du fur generations.  The farms which are on the sand bed of the main river course will also  be flooded due lo the back water,
The other Likely  negative impact on the community  could be krti of grazing  area  and animal watering  points if the reservoir area  is fenced or protected as sanitary zone and reserve area for silt protection.
The positive aspect of these dam sites u that there will not be any displacement of people from their residences since they  will Mt be affected by  the reservoir.  It is obvious that resettlement of rural people and the associated componatiotu for the different losses of property, farm lands etc,  are the most complicated to  implement in many  similar type of water development projects.
The projects have many  positive impacts on the development of the arex  Access roads will be constructed lo  the area  which is Ban - existent at present and due to  this them will be opportunities to  gel temporary and permanent employment which will subsidize the
IOCsubsistence agriculture.  There will be new markets created as a  result of the project Which wall enable tbc surrounding  farmer to  sell their agricultural products where they can get good prices.
6.8.1    Ix>rtg term effects
One of the most pronounced negative effect of a  water development project which has a  reservoir is (he spread of Schtstosomiasis since the reservoir becomes a  breeding  ground of the snail which is a  host for the disease if proper protection and prevention methods are not instituted.
The creation of reservoirs.,  though they  have their own negative sides as mentioned above,  it could be used for fishery  development to  serve as a  source of food and income to  the population of the area.  It could be also used for recreation if proper management is instituted.
The positive effects to the locality and the region as whole arc very significant Due to the presence of these dams social services like schools, clinics and other services that are non - existent now could be developed as a result of the whole activity in the area,
Wollo region is one of the most affected areas of the country by the recurrent drought which is caused by many factors like the erosion of the lop soil, depletion forests and other vegetation etc. The availability of electrical energy can share the burden of trees and bushes which are cut ruthlessly for many years without any replacement
107The presence of electrical energy  is a  must for the development of small and big  factories which can help to  alleviate the present unemployment problem and to increase the production of goods and services,
The urban population estimate of Wollo is over 460.000 out of which only those towns which are on the main roads are getting from the grid system The others arc getting  from diesel engine and some do  not have any electrical supply.
The benefits of these hydrapower projects to  wollo  and the neighbouring  regions are very  many  which will be difficult to enumerate. They will definitely have a multiplier effect oa the socio -
economic  development  of  the  region.  There  is  already  a  power shortage in the country which would limit the activities of investors interested in many development ventures. From regional development aspect   these   project   will   have   a   lot   of   contributions   to   other developments of the are*.
1087. COST ESTIMATE
The cost of the Beshilo  Hydropower scheme has been es*™'*’ based on the Kope of work and description of the development plan as stipulated in the alternatives layout.  This section presents the cost estimate and describe the basis of the estimate. The principal objectives of the reconnaissance phase of study are to determine whether a  pre-feasihility  study  should be followed by  looking  into  and comparing  different alternative schawl- This estimate,  therefore,  does not establish capital cost estimate for any  particular development.  Common cost estimates such as camp construction, construction of cofferdam with its appurtenant structure and potential cosLs which are estimated to  be a  certain percentage of the total construction cost were excluded from the analysis.
7,1       Batts of cost estimate
The reconnaissance study  cost estimate is made based on January  1992  price and is in United Slates dollars.  Generally,  unit costs for civil works are derived from costs obtained from recently  executed Neri Hydropower project by  Lahmcycs- International In addition,  cost estimating  experience and information obtained from studies recently  carried out in Ethiopia  were adopted. Price escalation is excluded from the basic project cost,
The cost of major mechanical and electrical equipment items and penstock steel were estimated based on the budget pricing  obtained from international manufacturer registered in January  1992.  Those were used for Neri Hydropower project Ethiopian taxes and duties on imported equipment have not been included.  As previously  discussed that all the potential sites with the recommended type of dams arrangements were analyzed and detailed cost estimates are presented under Annex  1,  2  and 3  accordingly.  Contingency for unforeseen works and incidental expenses of miscellaneous character which can not be reasonably predicted have been taken in to account in estimating
109rhe project cost The figures for these are 10% for the electromechanical equipments and 26% for civil works that arc adopted lor EFl-PAs standard.
Approximately  $%  has been ?dded to  the total cost for mgmrenng  and supervision by the consultant and 0.5% of total cost for client Own cost Annex E up EC 3 shows the detail cost estimate of Ute selected alternatives based on direct and indirect crw.
7-2 Cyt.Eitimite
The Present Value of Total Project cost at 10.0% discount rate for a life time of 50 years is used to evaluate all the sites. Thus the cost estimate for Abbay- 20. Abbay-2l and Abbay-22 are 171.1 Million USD, 273.9 Million USD and 2293 Million USD rapecrivrly.
The EVALS/EMINI cost eaurnate summery of the these sites are contained in Annex ] upto 3. The cost per megury and clcmcjtLs are as followst-
1. Cost Enin ate for Abbay-20
Civil works
Mechanical     equipment
and Hydraulic structure
Electrical Equtpmenl
Transmission feeder Total Direct & Indirect cost Engineering and
Administration
Clients own cost
89.812 Mil. USD
7.613 Mil. USD
11.990 Mil. USD
9,790 Mil.USD 119,21 Mil, USD
9.54 Mil. USD
0,59 Mil USD
110BASIC PROJECT COST 12934 MIL. OSD
PV TOTAL PROJECT COST
tai LQ.0% Diac nit} 171.10 MU- USD
(Fw detail information see Arm*x-1 of alternative F) 2, Cost Estimate for Abhay-21
Civil Works
Mechanical equipment and Hydraulic structure Electrical Equipment Transmission feeder
Total Direct &
Indirect cost
Engineering and
Administration
Clients own cost
BASIC PROJECT COST
15336 Mil. LSD
9.54 Mil. USD
15.77 Mil. USD
12.85 Mil.USD
I9L73 MIL USD
1534 MIL USD
0.96 Ml. USD
208.03 MIL. USD
PV TOTAL PROJECT COST
[al 10 0% Pte, rate) 273,90 Mil USD
(For detail information see Armex-2 of Alternative F) 3' Com Estimate for Abbay-22
Civil Works Mechanical equipment
and Hydraulic structure
Electrical Equipment
Transmission feeder
117.60 Mil. USD
1036 Mil. USD 16.69 Mil. USD 15.03 Mil.USD
Total Direct 4
Indirect cost
159.69 MIL USD
111Engineering and
Administration
Clients own cost
16.10  Mil. USD
1.00  Mil. USD
BASIC PROJECT COST 17326 MIL USD
PV TOTAL PROJECT COST
(at U3.p% D1k. rite) 2J92P MIL USD
(For detail information see Anncx-3 of alternative F}8. SITE RATING AND CONSTRUCTION SCHEDULE
84 Project Evfclujtioii
84-1 Gcotechnkil
Site Abbay-21  & Abbay-22  da  not have attractive topographical & geotechnical condition*  for the construction of a  concrete gravity  dam.  Moreover,  wkfill dam type construction is also not feasible due to the aon-availability of sound rocks in the vicinity  of the site as well w within a  reasonable and allowable hauling  distance. Again,  furthermore,  the cross-sectional area  of the sites are excessively  wide; no narrow openings eocitt- This situation affects the project cost serioualy. The provision of water conveyance system (a headrace canal or tunnel) is also not a feasible solution for all the sites due io the dissected valley, poor geological and structural features of the river embankment Due to the weathered basalt and tuff, water tightness of the reservoir basin and river banks are serious point of concern. Accessibility to the dam sites is also another point of major concern; the length involved for this is quite high.
The possibility of providing sufficient space for an open air power house along with
the natural location of a penstock route is also not feasible due to the geological and structural features of the area.
Due to  tire gentle slope of the river bed.the generation of heed for the required hydropower potential is almost nil. The required head his co be artificially created for the intruded purpose.
Site Abbay - 20 has proved to be, mote or Less, tire better possible alternative Horn the point of view of accessibility, geology, and location of quarry sites, for materials required for the dam construction and quantities available from them.  Suitability foundation for the rockfill dam has also  proved feasible.  Nevertheless,  it is unfortunate the reservoir site has been crossed by  faults which would likely  be a danger of serious leakage when it is under pressure during the full reservoir operation.
1138,12 Environment*!
The natural environment in the project area is impacted by the present land use activities (cropping,  livestock grazing) associated with the subsistence level farming  activities practised by  the local residents.  The impact of the project on ecology,  aquatic and terrestrial resources seems less.  Farming  and agriculture related activities are primary  occupation of the residents.  The displacement of these people from their fertile river side agricultural land is the important environmental issue for the proposed sites.  At this stage the need to  resettle and reestablish a  viable livelihood for those residents is no*  known so, environmental impact assessment (EIA) comparison for ail the sites are equally desirable.
82 Development Comparison Based on Capacity and Energy
in  section,  estimated  power  potential,  the  energy  and  the  capacity  of  each  site is estimated. These specific energy and capacity for all the sites are fbilows;-
SITES
INSTALLED CAPACITY (MW)
MEAN ENERG
Y
Gwh/yr
PLANT FACTOR
%
Abbay-20
29.5
86
30.5
Abbay-2l
38.9
118
31.4
Abbay-22
44.56
130
30.8%
The above table shows the resulu of the EVALS/EMIN1  out put,  derived from the 14  yean hydrological data  base.  The energy  and capacity  for Abbay-22 is large compared to  others.  This is due to  large drainage area  with the corresponding  (tow,  However geological condition would not permits the construction of concrete gravity dam on this site.
114a J      Development comparing
o^gengratipn tod Prof^Lcest
As  discussed  earlier,  (he  principal  emphasis  of  the  reconnaissance  phase  if  (0
compare the alternative schemes and not to  establish capital cost estimate of each tile.  Based on this consideration,  the cost of each scheme is specified and their particular type of dam is as follows;’
TYPE OF
DAM
alternatives
PROJECT COST  IN  (Million USD)
AVERAGE UNIT COST OF ENERGY DM U.S
Ct/Kwh
Abbay - 20
Rockfill
171.10
30.5
Abbay-21
Concrete
Gravity
273.90
31,4
Abbay-22
Concrete
Gravity
275.40
17.67
The  above  table  indicates  the  cost  and  the  corresponding  generation  cost  for Abbay’20, Abbay-21 and Abbay-22. Considering the generation cost Abbay-
22  seems  attractive  than  Abbay-20.  However,  taking  into  the  project  cost  that would  be  involved  for  the  treatment  of  foundation  for  concrete  gravity  dam at Abbay-22 would be expensive,
H.4 Over ■!] site ratine
The Abbay  ’ 20  scheme development seems more or less economical than the others at this stage of time.  This ii based on the preliminary  findjngs,  and development comparison of generation and project cost.  The findings prove less project cost but more or less similar generation cost with Abbay-22.
115The most economical phase of development,  al thia  sUgc of time,  would be the development of Abb*y-26  followed by  Abbay-22  at a  later date.  However, both sices needs a  detail assessment of the engineering  and geological aspects prior lo  any  measure of development plan.  In tine with this,toe availability  of construction materials and accessibility  to  site have to  be tooled into  and investigated in detail.
Should any  site in the BcshiJo  sub-basin is to  be implemented,  Abbay-20 should come as first potential priority  site.  However,  the accessibility  to  the site,  and condition of the faults is the major concent that needs to  be tooled into seriously and in details.
8J       Construction schedule
Engineering  and Construction schedule for the Beshilo  scheme (Abbay-20) has bon estimated to  be four years.  The time frame for the construction period is estimated based on the assumption nude on standard requirement for Medium Scale Hydropower construction periud which,  tales into  consider additional pre- engineering  designs,  site investigation and field survey  works during the period of construction.
The facts that the project components require specialized contractors,  toe construction schedule is preferred to  tie with those requirements.  The early commencement of the construction of the access road followed by conjunction of camp inorder to  facilitate the smooth progress of the project The access road and location site of the camp are the greater percentage of the construction work is active in this area.  The construction schedule for the potential hydroelectric project (Abbay-20) it shown on Figure 20.
1169,
CONCLUSION AND RECOMMENDATION
The   reconnaissance   studies   described   in   this   report   have   defined   the   ultimate dev elopment potential of the Beshilo project
9.1 Conclusion
Basal on the reconnaissance level of study,  an optimum concept of the ultimate project was established by  formulating  less project cost with optimum energy  production at a  reasonable guarantee of this energy.  Thus Dam powerhouse development is a typical solution for the Beshilu valley,
The theoretical potential of the Beshilo  project area  for Medium scale Hydropower generation is about 863  GWh/yr.  118,1  GWh/yr and 130.0 GWh/yr for Abbay-20, Abbay-2l and Abbay-22 respectively.
The inclusion of hydropower potential of Abbay  to  the existing  system would substantially  improve the voltage profile of the long  Kombolcha  -lcotobte line which is frequently  subject to  voltage drop.  Voltage drop in Addis Ababa, D.Zert and Nazareth area  is mainly  due to  transmission lines or transformer over loadings.  Rehabilitation of some of these lines and transformers will alleviate the problem.
The overall performance of the power system was analysed laying
rehabilitation requirement into consideration. The outcome obtained was good.
In general the development potential of the Beshilo  sub-basin is dominantly dictated by  the geology.  Hydrology,  and the natural topography  .  The availability  of construction materials for Abbay-21  and Abbay-22  do  not exist around the vicinity of the sites. Though the geological structures at Abbay 21
117t nd Abbay  22  »  fakly  good,  unfortunately  Abbay  21  a  fault near the aite- Though this will require former mveatigation.it would entail additional cost for lhe treatment of foundation depending  on the extent and seriousness of the situation. This is a serious matter that needs special attention.
Looking  al  the  outcome  of  the  generation  cost  and  the  basic  project  cost,  the cost  of  energy  per  KWh  has  proved  to  be  far  beyond  the  acceptable  norms  of standard.  The  energy  cost  is  the  decisive  parameters  for  final  recommendation in any hydropower development schemes unless the social factors dictate so.
However,  if the social factors dictate to  the contrary  and if there is no  any alternative potential site within the vicinity  of the region,  the development of Abbay-20  vid Abbay-22  combined could be taken in to  consideration for further studies and subsequent implementation since most of sites are located not far from each Other.there is an understanding that a commoc infrastructures could be implemented which could give more rooms for reducing  the cost substantially.  Along  this line,  the generation if electric revenue with lhe combined arrangements could also  be feasible but this needs to  be looked into the detail.
Thus in conclusion,  the studies carried out at this reconnaissance level if the Bcshilo  Riva  sub-basin could only  be justified in view of the proximity  of the she*  to  the long  Kotobei - Kombolcha  line which needs to  be upgraded urgently.  Further the need for socio  - economic development in the area dictate the development of the hydropower planu,  particularly  AB *  20, However,  from the results of the cost analysis,  the envisaged power project seems to be not economical due to the cost of the civil works and accessibility of the site compared to other projects relatively having the energy and capacity potentials.  It it thcreforc.suggcsied that the economic aspects of the project will needs io be looked into in details in future studies.
118Should th= Bahik, R™ bu
for »■«« 
<*“ “ AWMS,-2°
scheme), the following recommendations are as follows:-
9.2 Recotinnendallon
The  recommended  studies  would  include,  but  not  be  limited  to  the  following technical tasks.
9 J, I Topographical Ikms
Obtain L50,0M scale mapping of the entire project area.
-    Carry    out    an    open    traverse    survey    starting    from    the    BeshiloJita junction   up   to   the   end   of   reservoir   Abbay-20   (Le   longitudinal   river profile)  and  confirm  with  the  present  longitudinal  river  profile  made  by the Helicopter GPS (Global
positioning system).
Locate and survey alternative access road and tran^miferinn line tout
Proper  diversion  studio?  should  be  made  for  a  recommended  type  of diversion tunnel or canal.
Review adequacy of rock cut spillway.
Determine   optimum   Location   of   dam-powerhouse   arrangement   with minimum construetiCKi cost
119922 Geological and
A. Slope SlibHity
_[Rg>
The slope is unstable because of the following reasons-
1}, presence of ash and tuff below the basaltic
mass.
2) .       slopes are steep and the rocks are either weathered
and friable or soft and weak.
3) ,       the ash and the tuff, and even the basalt are easily
soften when wet, and have a potential to fall.
Therefore slopes (reservoir sides) must be protected by  either a concrete pavement or a  layer of rip rap,  however this is extremely expensive.  The most practical method would be a  large scale slope protection by  planting  fast growing  vegetation and installing  surface and drainage control systems.
B. Reservoir Sedimentation
The geology  of the catchment area  of the reservoirs is covered by similar rock types fix.  weathered basalt,  ash and tuff) as the reservoirs themselves.  These rock types are easily  credible.  especially  during intensive rainfall,  and runoff prevailing  in lhe area.  So  the expected sedimentation in lhe reservoir will be very high.
The   possible   control   measures   should   include   plantation   and   proper formation of stilling basin.
120c. Ptnnw Witty of the Reservoirs and Abutment
DcpcjiU of ash and jointed basalt are known for their highest permeability,  that makes the water tightness of the reservoir questionable.
Seepage beneath the dams is expected because of the permeability  of the rocks.  Hence,  grouting,  a  cutoff trench or installation of a  pressure relief system must be considered during  future exploration and design stages.  InesitU t«l5  Mi necessary  to  provide data  on permeabilities and to  evaluate the potential seepage loss through abutments and foundations..
D. Structure
The major fault in Abbay - 20 (foult-A) and the fault in Abbay-21 need a  more detail investigation using  drilling  and geophysical exploration (electrical sounding) to evaluate the extent of alteration and depth.
t. Access Road
Access road,  for the use of large vehicles carrying  heavy  duty exploration equipment,  need to  be constructed and rehabilitated.  This road will also be needed for the pre-foasibitity and feasibility studies.
Generally the following items are recommended for further detail studies.
investigate the general ground water conditions (install piezometers) in the reservoir basins and around dam axis.
121make   an   assessment   of   possible   ground   water   control   mtaiura   aod water tightness in ihc reservoir.
obtain  rwk  sample*  for  laboratory  lest*,  for  further  design  and  choice of material
conduct geophysical investigation (Seismic and Electrical }.
perform intensive site specific geological mapping along the proposed
sites.
perform field investigation in the form of test pitting, test trenching and mapping to verity the nature and activity of faults tn the dam site*,
conduct further investigation in the areas closer to the dam site* for tockfill quarry material.
carry out a rite specific study of the seismicity dam rite and other project structure.
9.U Hydrological Items
to die major
In  order  to  come  up  with  tangible  results  in  the  subsequent  phase  of  the  study it is advisable to conduct the following hydrological works.
Sediment  sampling  works  should  be  carried  out  at  the  bridge  upstream of the abandoned hydrological station of Beshilo river near Wegcletena.
Discharge  measurements  should  be  taken  using  different  techniques  of flow measurement such as float measurement and others
122Since the flow during  the rainy  season u very  flushy,  the rehabilitation of hydrological station should be considered in such *  w»Y ,K continuous operation is guaranteed
In addition to  installing  staff gauge in particular for high flow records it would be more practical to  use pillar marks for stage recording,  so dial it will be safe in case the staff gauge is washed ouL
To  accomplish the above works it would be more ideal to  organize an isolated camp near by  the gauging  station with complete camping facilities,  appropriate personnel and well organized logistic support (vehicles, supplies elc).
lt should be borne in mii-di that the coming  rainy  season's high flow measurements and sediment sampling  may  require time and resources in formulating  and implementing  the programme unless abrupt measures are taken.
fLiin   gauge   station   should   be   installed   at   representative   places   in consultation with NMSA.
92-4 Env iron mental (ElAl items
Thu     Study     comprised     a     preliminary     investigation     of     environmental Lonsidcrations with data collection and analysis at the reconnaissance level.
Examination of the comparative evaluation matrix  fTable 5.1) indicate a number of important environmental impacts and these should be carefully studied during pit-feasibility and feasibility studies.
123Further Hudi« are required to elaborate and confirm the recoruwssance
findings. The most critical issues for future study include;
]) Social issue*
Social and ecological effects of reservoir inundation.
- loss of agricultural land
Joss of forest and grazing land
population resettlement (if there are any at the time of studies)
U) Aquatic Resource,
Which include problems of aquatic weeds, investigatian of water quality and
fisheries resources.
Ill) Public Health concern*
Thia  should include study  of public health conditions,  future project effects for increased incidence of water home and water-related and'or ryportimifirs to improve the health condition of the people currently  residing  in the area Surrounding the proposed reservoirs.
k) Vegetation sod wildlife issue*
Much of the existing  information concerning  forests,  vegetation and wildlife of the study  area  is very  limited.  Consequently,  detailed investigations will be required for inventory  of vegetation and wildlife resources in the reservoir area. Particular attention should be paid to endangered and threatened species.
124v) Terratriil and aqutk Ron ifld fauna
Investigate the Impact of creation of reservoirs on local population ahd
floodplain ecology.
vi) Waienbed
EfTeCls of existing and predicted land use in the w Hershod on thc fimeboning and longevity of the dam and reservoir need to be studied.
135REFERENCES
1,            Sratisteical   Absract   1992.   Central   Statistical   Authority,   June   1994,   Addis Ababa.
2.           Population  Estimates  of  Regions,  Awn]as,  Woredas  and  Towns.  1992,  Central Statistical Authority Statistical Bulletin: 101, September 1992, Addis Ababa.
J, Nenarit Gazeta of th ^Transition al Government of Ethiopia. Proclamation No.
7 /I992, 51" year NoJ 14* January, 1992, Addis Ababa.
4. National Policy and Ethiopian Women, The Transitional Government of
Ethiopia, Office of the Prime Minister, September 1993, Addis Ababa.
5    Population    and    llousinn    Census.    1984    .Analytical    Report    on    Kefla    Region. Office  of  the  population  and  Housing  Census  Commission,  July  1990,  Addis Ababa.
6- E3GS, 1992. the Geology of Ethiopia. Unpublished report.
7.           Meria.  G.CLal.  1973.  Geological  Map  of  ethiopia  And  Somalia,  ai  1:2,000,000 scale,
8.           Ministry  of  Mine*,  1995.  The  Geology  of  cbida  Area.  Hydrocarbon  Devision. Unpublished Report.
9.          Mohr. PA.. 1969. the geology of Ethiopia. Unpublished Report.
10.        Sovthere Ethiopia Planning Office, 1988 Master Plan of Western Ethiopia
11.        Alcltu     Reconnaissance       and Pre-feasibility Study, EELPA/ACRES INTERNATIONAL, 1984.
12.       Master Plan For The Electricity of Sri Lanka-GTZ, LAHMEYER INTERNATIONAL, 1986.
13.      Aid hi Hydroelectric Power system study, EELPA/ ACRES INTERNATIONAL 1993.
126ANNEX-6
Composition of the Study
TeamThe Bcshilo  river Medium scale Hydropower Plante Development reconnaissance Study  wai carried out under the Government's emergency  Programme as the first phase of studies tn exploit the hydropower potential of the priority sites idcnlifed in the Blue Nile river Basin.
Ato Tejfaye H/Giorgis|Tcam leader)
Ato Wadi Abdurehun
Ain Tesfaye Wolde
Ata Begosew Abate
Ata Assefa Salih
Ata Abebayehu AJemu
Ato Dagne H/Michale
Ato Temesgen Tesema
Aid H/Mariam Beyene
Ato Tcshomc YihualAShet
Ato Dejene W/mariam
Ato Alenafe Beyene
Ato Luelstged Tadessc
Ato Lculseged Tesfaye
Ato Leulseged Bekelc
Ato Til&hun Asmara
Ato Daniel Sime
Ato Hailu Tekchb
Ato Amare Negash
W/n Meserct Teklu
W/ro Mcnbcre Seyoum
W/ro Hinn Alemayhu
W/rt Rahil Gimm
Civil FJigincer,EELPA
Elcc.Enginecr^EELPA
Sanitary Engineer, MNRDEP
GeologisuEIGS
Surveyor, EELPA
Surveyor, EELPA
Surveyor, EELPA
Driver, WRDA
Driver, WRDA
Driver,EELPA
Environmentalist, WRDA
Sociologist, MNRDEP
Hydrologist, WRDA Mechanical  Engineer,  F-F.l  PA Mechanical   Engineer,   WRDA
Hydrologist, WRDA
Hydrologist, WRDA
Drafts Man, WRDA
Drafts Man, WRDA
Drafts Man, W RDA
Secretary, WRDA
Secretary, WRDA
Secretary. MNRDEP
r
EELPA;-
WARft-
EIGS;- MNHD£P>
hJhKjtUffl LkuTnc
Aulhcnry
Rtniuvc And Domkjfmaj Atihriiy fcJh»pun Ir^rje eftwfcjflka] Sumy
Mining   of   NaturaJ   ReiLrjn.^   DtvdofaoA
•cd EnvjiximdutaJ Prt*»cli«ANNEX-7
Project Terms of Reference
(TOR)PHOTOStopography of eeshilo area
PHOTO wo. 2 ACCESS TO WBGEL’TENAPHOTO NO.3
ACCESS CUT GP SERVICE, LEADS TO GULYAI--------------------------------- 1 1PROTO NO.7
STEEP SLOPE OF BESHILO IM THE RIGHT RANK
PHOTO NO. 8
TUFF AND ASH IN THE LOWER SLOPES BENETH BASALT™ 
IHTSRC^ED BASALT ASH AND TUFFJ
I
)
I
]
1
I I
1PHOTO NO. 13             PART OF FAULT - B IN XEBAY - 20
PHOTO NO,14 PROPOSED flUARRY SITE S KHS FROM AEBAYv 30
■■
1
rPHOTO NO, 15 PROPOSED QUARRY SITE 10 KMS FROM DAM SITE ABEAY - 20.] ] ] ] ] 1
I I I I I
PHOTO NO.17               RIVER BED      deposits near dah site abbay-zq.
iPHOra NO.19                SAM SITE ABBAY-20 LOOKINK U/8'tV
PHOTO afloat RIGHT BAiJK VIEW OF ABEAY - 2 0
PHOTO NO.22 DAM SITE ABBAY-21 LOOKING  /
aSPI5QT0 NO.23 LEFT BANK VIEW OF DAM SITE ABBAY-21PHOTO NO.25 DAM SITE ABBAY-22 LOOKING U/S
PHOTO NO.26 DAM SITS ABBAY-22 ALTERNATIVEPHOTO NO.20
RIGHT BANK VIEW OF UAH SITE
ABBAY-22FIGURESiOCATON AMP QF TH PROJECT AREArJ-
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Seismic risk map 100 ytors intensity
seismic zone: of Ethiopia -bed rock acceleration
RATIO CH o
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------ LITH&lCGICAL contact
>. ■'
-______ FAW.T
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SfC .OG/Ul MAP OF OAMANT
Figure -5
> SQOQo^□OGICAL    CROSS-SECT'iON    AT    AXIS W                                     ON BESHLO RiVEPJ
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. .DAM siTg
'_____ litj*olo<;<al contact
___ FAULT
*■_____STREAM
0____ viu«£
G£t LOGICAL MAP OF DAM SITE AND RESERVOIR arfa FOR AB-2!
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GEOLOGICAL CROSS’SECrON A? DAM AXIS A0-?i
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ProjecJ AR-JO, A«-?l AM
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AR M. AR-21
AB-22
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HYDROELECTRIC PROJECT ■ POWER STATiCN S!HGL£ LiNE DIAGRAM (A3-2?)
Figure 2J
Not to »calo
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AwPJ-OyFlow Duration Curve of Abbay-20
Figure:- 24Daily flow in m * 3/s
Flow Duration Curve of Abbay-21
Figure:- 25Daily flow in m 3/s
Flow Duration Curve of Abbay-22
Figure:- 26££fi£g& __CROSS SECT/ON OF THE PLANT
%
PObuco
tower house arrangement and general cross-section
AB_2°
TOWER HOUSE CROSS. : SECTION
> I
POWER PLANT
Fig >27
Not to acetoGENERAL CROSS - SECTION OF THE POWER PLANT
AB-21 H.E. POWER PLANT
] Fig:-28
POWER HOUSE ARRANGEMENT ANO GENERAL CROSS-SECTION
Mot BO scalePOWER HOUSE^ .PLAN
GENERAL CROSS - SECTION OF THE PLANT
POWER
IOUSE CROSS
I
AB-22 HE. POWER PLANT
POWER HOUSE ARRANGEMENT AND GENERAL CRO
SS-SECTION
fo wo*ANNEX-1
EVALS output for
Abbay-20mw
0 0 0
0 0           0 V          0        0        00WW0  0 *
f n         0* 00       00 0 0 0 0
0 0
r              0          0 0 0 0     < 0 0 < m** f                 <00          <0 0
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iT»»»            rPFF« ■
Concrete Faced Rock ft II
t>*r<
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- table or dWTEins for project ivaluauon slatiary
E*WJM LtJTiHG 09 juti
Page i
Projact Alttm
I rue Cap F»cl
Ruh data AlWTOVl
M5HD1G *<... A.......................... 1.00         -     1.50    ..    09    Am   1995 --
daicrlptlon
LAYOUT 4
-6O>-Roekf1l(  laced     cancret
Png*
1
t................. 1.D0        -    2.JO    ..    09   Jun   1995    ..  WFEkfHCE    LAYOUT 4                    1W*«wl *-56)~RKkf1U     (Kri concret ............ .........................................  1
C................ 1.00         -     1.50    ..    09    Am   1995   ...      WfltFiCE    LAYOUT 4
RockflU  laced    concrvt............... ...................................  1
C................2-«            -     2.50    ..    09   Am   1995    ..        WttfiKE
LAYOUT 4 16A4-*ar1-46)-Jtockf1U *Krt crew........................................................................ ,,, 2
0 ...... 1-00
E ...... 1.00 • 2,30 .. 09
- 2.50 .. 09 Jlh 1995 .. AtFtaf*Cf
1995 .. REFEREKt
F ..... I.W - 2.50 .. 09 Jim. 1995 r. REfEHEKt
LAYOUT ( 1444‘wl
CAiOUf C
LAlCLO (
faced cwrd ,.............................................. ,,,,, 2
1134-«rt-WB®0ClflU  faced   cone ret...................................................  2
1i2A-aad-A4)-R«*HL1  faced    concret ... ................................................ 1Rnj’i'rr.
Hydfopswtr PUnt* *Pfrj«cli 'Vltf - Analyalt ni IEE* ProJ« E
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- project evawmiw  swn
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tier of Tant
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---------
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!*■■■*■■■■■■*■■■■« IM--V9EBRW ■ ■■»■■■»&
SprcLYLi; GmTV 1i «i. c»E<
Capacity --.............................................
Cwt
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pppppp.............*
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A        2.-M
31.1 23-07 T648.0 1548.0 0,5
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233     Ql
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27.62 19.27
104
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172
226    0.7
10881              25.87              5O.35 7585             23. U0               28. to
S 5942 21.47 26.31
5046             20. B5               78.J6
11269              23.76                26.53
7861              21.82                25.88
1      2.00
31.fi 23.07 1644.0 1546.0 0.5
661
M
30.5
36.70 28,13
112
57
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26,46
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120
52
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C      1-00
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641
44
40.3
18.35 10.55
96
82
167
219    Q.6
5239              20.43                26.7D 11688              22-91                25.12Concrete Faced Rocklin Dam
Alrj-rrwHma i
HraroDowfr HiamTB Project (vp-lf - AruLyili *F «*"
PrfljKt USHCU
• TA®LE OF COHTERT1 Project Alternative F
EVALi LI III MG
JiJW 1WS P*pr T
Initll led CRpM^Ey Fftflgr |(F a 2.Ki
Gcntenti
Pipe
- $VWAT P£R COST CAlEWBT AMP ELfrfEMT ................................................. ___
- GVERAL flHMAPY OF PROJECT COST ........................ ................. ........................
, .^................. ... ..................... ..rr.34 . ........ ............................ ...........
i4
............. ................ ................... .. ................ ... ................................................. ..
2
L
-
FILE WERWItlf „„„........................................................... .............................- SUwtT HR TOT CA1EMWY AMD ELFKNT
Project AUtrnitlv* f
EVMS LISTING 0? JUM lW
IfttCtLIed Opacity Full* ICE -
?
2.00
COS1 ESTIMATE (DEiftT) FDA 11V11 JTRIjCTUMS
■.■>■ ■IHKBIililiBiBBAA ■ >i»■■ ■■ ■■«.■■ *■> ■ ■ ■ ■ ■ ■ ■■ aa■*■■■■■■■■■
■■ ■■■>■'■ ■ ■ ■ ■ ■ ■ !■■■■ ■ ■■■• ■ ■■■naaai.i.ua
PERCENTAGE OF   TOTAL C«F
Coll Level' J tn 1«2
TOTAL DOST      tlKMO USS)
ElEMEWI
Itt          For          Im    Trill        Lk                     For                   Tm
Irial
niiginiistrun ■■BaHBVianiiBHiBnamninatiEKEirnwM
Pfl
10.7        04.1           0.0          94.0               6126,              4W7J,                        0.             16300.
SpiLLwy                                                                                                                                 13          13           0.0            2.0                   MT.
Powerhami, Including tMUchyird
ACCOM rod*
sm total                 cm/d tixn)
1,1          13           0.0            23
TOO.
ora. 0.
?w. 0.
0.0          0.1          0.0            0.1                       5.                    34.                     0.
155?.
150Sr
39.
113         M.7           03         1003                 7927,              51472.                     0.              593 W.
COS? fSTJHATE (OIAECT * IlttltfCI) FOR «OWE CAL «WJM«MT ANO HTDRAMLCC tTLEL STRUCTURES
■ifliilaalHHniBdiliiaad
flFNFNT
rrBB*iii!laaa*aMV»Ha>MailH9MM"'",i'l't»V ■■■■■iTiiimiWTrrrfWMWri IITF rrrrf mt ■■■EIIKIIli.Ill 0 JUtii.fa . utiitl
ntCEMTACE 0? TOTAL COST
Loc far Tin Total
CW Iml; Jin 1W2
TOTAL COST {1000 USS)
Lw
For
Th                  TctSl
Power Inflict
Pwtocfc
0.2
0.2
10.3
7.9
0.0
0.0
10.5
0.1
Ik
15*
714+
540,
0.
Q.
7Z5.
563.
PoverrwMM*, including ftlf^hytrd
03
01.0
0.0
fil3
20.
$60$.
0.
5633.
SUBTOTAL
(m/d ttH0
03         993       0.0   100.0              54.
6067.
0,            6921.MIQ-X
frrgjw;! fcFSKOU
FatJl.LR S-Cllt HyffrQpndtr
Ptejtei EVALS - Awlvilft P< ■<» PfojatL
- W*AIT HI GOH CATEGORY W (LIRE Hl
►ra,|*ei Alierratlwt f
EVALS      LISTING      00      JUN      1W      Px^t      3
trucil ltd L*(s*dty flexor [Cf ■
2.0G
COST ESTIMATE (PlttCI * 1IOJRECT> FDR ELfCTMCM EOJ1PHFHT
Cort ltwL = J*l IW?
MtCflHAa or  TOTAL CO«
TOTAL CO5I      [fcOOO urt>
ELEMENT
PMf«fhcMf*r includlfif taftchyard
roe          f»k   IctaL
KO 99,0 0.0 100.0
IK
FW                    Tu
local!
■05 r              ID79K                       0.                WWD.
M10TAL
(w/Q T4BM>
KO         w.o           0.0       100.0                    105.              1D795.                      0.              10900.
OKI fSTIMTf (C1MCT ♦ INDIRECT) ft* JJtMWriSIM ««D« LIKE
Cost Level: Jen 199?
PERCENTAGE OF TOTAL COST
ICTAL C«1      £1000 UCT}
ElEMEm
Lac          Far          Tu Total
l«
For
Ur             Total
Ttadrr Ifrw
9.6         9<M            0.0 100.0
057,                 8044.                         0.
4900..
$WFQTAL
rnE»riirl *■■■ mmn irmw^s
TWW)
ji ■■«■■■■ ■
KA 90.4
■■■■if MitlliHPUfniiiiiiwFMiMfl
0.0 100.0                           057.
0W.
0r
flMG.
b EiatziiiEErrtxiifTf^i ill ■■■iiixeij 'Li 3 j j j.
poOIma Wak« taydropo-^r tier"* Project 1**11 -
4,4 attt Project
Project 9t$w014
- OVERALL iUWMJIT OF PRCUECT ttltl
I**l5 LUI |»£ 09 JJW 1V05
P**, b
Project ALlkfMtEww F
Iftitviird Cepeel'y Pictor LCf ■ 2.00
BtEAUJAM Of COSt 1TEHS
Colt Level- 1992
iMiiiatki.i.imii
PfRCfRTAW 01 TOTAL COTT
TOTAL COTF
ELEMENT
LW           Far
lax Total
Itt
For
< low Utt}
Ten
lacel
CIVIL UGWCS
- Direct coat
• Indirect caec (
6,6         43.2           0.0        49.0
7927-
iu?z.                      0.
26,C x direct coat )
5.1            7.0          0.0        13.0                  6009.                 9355.                      0.
ww.
1$4U.
• CentLremclea <               20.0 x direct * indirect cwt )
2.4          10.2          0.0        12.6                   ?M3,              12165.                      0.               14969.
- Tatal for civil
works
U.1         61.2           0.0        75.3                 16019.
nw.                       0.              B9S12.
WCHAMCAL EQUflFMfeMr Mfl> MTORAUUC STE£L STRUCTUtFS
■                        Orrecl
end
indirect
cwt
0.0         5.B      0.0           5.B                    54.
* ContlnsencFre ( 10.0 1 direct * indirect CWI ) 9.0
- Forel for ■*ch*nfcc>( equipment 0-0
0.6            0.0           0.6                       5.
6WT, 0.
«T.                         0.
6.3           0.0           6-4                     60.                 7554.                        0.
6921..
692.
761L
EifcnrcAL
-   bi reel and Indirect tott
■ Cent I r-jenc I e* ( 10.0 X direct * indirect coal >
-   Total for electrical equipment
0.1
0-0
0,1
9.1            0.0            9.1                   105.               1079$,                        0.                10900.
0.9            0,0            0-9                     10.                 1080.
0,
10.0             0.0         10.1
iik
1107$.                        0.
1090.
1199th
THAVWISSIIX FFEDft L LNf
-   Direct end indirect rtHt
-   Cant Irvenci’ee ( 10.0 X direct * indirect coat J
- foul for rrer-Milfilon deader line
0.7             6.7            0.0            7.5                   057,
3X4,                         0.
0.1             0.7            0.0            0.7                     06.                   004.                        0.
o.e            7.4       0.0            0.2                   942.                  M40,
0.
6900.
NO.
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Cite fCfler«l«d .... r 09 AW BW5- 1AOLE OF CONTENTS Fqb MOJCCT IWU1MTI0N feOHUH
M*d|iaa Scat* Hydrapowr Plant* Prajttt EYALS - Aftalyal* *F IE5H PrO;tCT
FvilM LI$TW « JlW !M P*?* i
Project Ahum Jnat Cap Fact Run data
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■ PRWEGT E.VALU4T1M SUMMARY
LI5TTMG W JOH 1995 rw 3
AHUmXiwr F
- REFEHBU lATWt C 1424--wi-<43-Cwicret Grrrlty d»
liiiiinai
flit Irnt
Cep.
Fk<
Rrri     L oofl Km           Keen w»in
Flint Ter* Dp»r Tell Need
Feet FL<m Level Voter L»
Ave.
ft*r
Wei.
fief
of
let.
Cepechy Erwrgv Cwt In oil 1 li wi Spechlkc
Ctpeel'y
Cenereelfin mil
Tern
■pl u    Neon Guer    Neer Over    'reject       Mfi!    W           Cwt        flverept  Weighted
{-)         (J) («3/») (■>
(■) <W          <KCK>       W     (X>         (W> <*)        {G*> <X»      C«»J      OrttJ    Cl)         (IAMJ      Ic/kMhl      [E/krii)
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23.07 IA24.4 15X2.A 0.5       511     32   <9.7     15.21 11-59         47     49          IM         210    0.9       13657         32.49          M-55
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- TABLE Crf QQWTIHTS
Project A L t ohm 11 v* J
(VJ4S ■ toilrtls or BFSH Preset
EVALS LISTIWG OJ JUN 1995 Prqt
EnstiLLed fepwity r«ior tt» ■
Cornel
-   wJ*Ujfr PEN CDS| UIECOT JUTO ELEHEIR............................
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Projtci *€5H022
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PLrni Projwt IVALS - AruL/*f« nH «sh >rrj«ct - SUMMIT nt CTt CAffM** A® ELEBCM!
Prgjftt AlTtmatlv* f
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iiTf.Baxt .iittl I ■■■■■■> I ElIlIICrTril II I HflfVtri I ITfUI J | B I |
PfKtlW Of I OP AL COST
L«           far            lu
Cost Itrt-l t 1992
WM Gear {iWfiirtij
Loe
Pm
lu           T-b?*L
Om
4t.r
41,0
0.0
71.6
W32.
3W6.
0.
71254.
Spi L ttt»y
0.2
0.2
0.0
0.4
160.
W.
0.
255.
foM-rhwAt., 1nclvdJi*>9 swiccKy*rd
13
1.2
0.0
2.4
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972.
0,
IBM.
fcCIU r ords
0,7
5.0
0-0
5.7
543.
MB.
0-
4306.
subtotal
•*•«•**■
51-7      45.3       0.0      100.0                40201.
0,
77700,
COST ESTTKATE tPRECT * TWHREClJ FC* rtfCNUlCAl CaulPw£«r AM> H TDiALn.lt SlMl STRUCTWES
C4il Irwl; Jin 199?
■ ni|.4f IpIkllBIEIEECI IITI If if a**i ii J4J JIHf iff
i« JiHIinTITII I ■ ■■ ■-■ al J JXZEDEIIIIB EI El FBBt iH'lfc.iliEliaiBllISElllI mi&U-U
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CENTAGE OF
TOTAL
COS!
TQIAL COST <1000 U5
»)
fLEMFM
l*C
For
Tbk
IflIAl
Lee
Far
fu
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Power foffttv
03
W.J
0.0
10.5
15.
974+
0-
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0.2
7.2
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7*4
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0.4
IT.7
0.0
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0-
7752.
SUBTOTAL           [w/c (UH)
0.7    W.3         0-0    100.0                M.           9352.
0.
9420.WbA
Frajaet ttSHQH
MriiuB $Eita
PL*r.fci Pr*iME EtfACI > RMlyaH •f IE5H ?T<-j«E suwAt      Hi     CW     G4Tt«av     AM!     ElEWEHT
PreJ«< c AL terr**: 1*+ F
EVALS       Lliltmi       Oi       jiA       w      |rw            j liMtaUH Cjpjcliy Ficljpr |fF ■ Z.OO
PERGEHTAa Qf TOTAL GMT
IOMl con (IflM U5i)
tLLMtMT
LW
Ed*
Tu
Total
Lm
Ftf
lai
laiaL
PoMfhGMft-, including
awlfchyard
1-0
W.fi
0.0
100.0
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1503k
n.
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M ■ ■■ —
WtfQFAl
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1.D
W-0
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0-
1517?.
C«T ESTIMATE (DiHEO * IMMftKO FW TAWS* 15? TO* EEEDit LIME
a ■ iirakiKiiiu ■ ra ti BBBBBaaBianit<t*■««<< ■ ■ u*i«Bij:::iriiira riaarra ■ ■ ■ ■ b b ■ b«■■ *aaaiaaiiaaaHUipnaiaiiiPPxbi»lta.ba llm ■ ■ ■ •■ iIbbbbbbbbb
Irrtl ; Jw 1992
,,
HRCEHTAAI Of TOTAL CMT
TfllAL W$l (l®0 WD
FL EM»T
l«       For
Ittit
LfrC                    For
Trani«i'i-J ioi Faeder lllW
00.1           0,0      1W.fi          1354,              12311,
3»
0,
Ig'aL
13647.
SLSFOTAl
(rt/fli Ellinj
0.0
«.l
0.0
100.0
f3M.
1311.
IL
13667.1.
L—J             L—i               t—4
i b—
u-i L_j
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PraJftEl IESH022
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EMALS LJ&llHK 03 jyy IWl Paqe 4 |T>M«11«f ttpKlfv Fule ar IcF ■
?,M rvBii»aB.a
H[i4KMi QF COST lU"f
Ca»r Iwelr Jan mi
PEtCWAGE OF
TOTAL COST
tofal con (icoo ut*j
ILCMtH
Lac
For
Tea Tota
l
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for
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■ ■■■ ■■■ »a ■ ■ ■ ■ ■*■»*■*!.■■■
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■ ■ ■ ■miirrn ■■
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Civil LtjijS
ftittCt cw!
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23.5
0.0
41.7
40201.
37579,
0,
77700
Indirect cwt < 26.0 i dir<eE                                     >
5.0
7-7
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12=7
7973.
12250.
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KECNMICAJL £gujntf#3 JW RTOUliLlC STCEL iltUdWl
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935?.                       0.
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0.0
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0.0
6.5
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0J
M
0.0
9,5
146.
13033.
0.
15179,
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0,0
0,9
0.0
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1503.
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0.9
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9.4
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13542.
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_________
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3
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Project UVN022
Kediuv 5-ciie HydrppoiMr Flint! *rojtn (VAlI - Jir^ I I ■ aF gt iH Project RESULTS Of RESEtVOJt WI10“ K4 EC0NMIC FFJU.U6TIOI
Project Alraragtlv* f
fm? L3FHHG DI JLK IW p4^(
Distilled tefuHty racr&r IC* -
5
?.<»
-Plant fictor
•Win »trra*rf|p- Cim-TWJ, 1« «ncM- of Ptati
Allege / W*L InFLeta
■Rvivr.^ir 4p»r«f1ftg l*v*ll:
M**fl
Mfrdiu
30.E X
JJ.6 -J/s
M.7 X
1430.0 -tL
1425.0 -I
I toe.. 0 «1
-Nirjln.il 4«t of 1 lw af &u*r*nxeetf rapacity
-Hwilnii («t Dt 1 XLti 01 frail mirad rrwrgy
-
■■rarginiL sect ol 1 kWh of secondary energy
(Vied for
-litle prfrjwMte ««T
'Jmitl m; ««
irrangnvnt d* power ccnpenenekS
45O.0 1
4.Q
cmis
173.3 nig * a.9 Mi* t
HIM *[ Mlnlu                                                0
-C*ih dl KtwriiwnT (t) ftwF 4 ywi gF gpns^uctinn
16.2/ 33.0/ 33.az 16-2
Level W. X rAC-rrM
14OT.1 Ml
a 10.0 X discount rate
229.3 Mio t
■1*1 Ln* rtf «E fwiT IW                             Mirim
PHnfrut
-3i0t.il dPciigri dJithirpr
lja.t mi
F347 * Ml
r
lUfl.D us I
PV foul project cwt
(IIfitfee 50 yeira)
-Cost per kW rapgclty
a B.Q X dltCfflrfl rate
3   ID.D    X    dlsrarst    rate a 1?.D X dlUME rat*
479B. S
5030. 1
5271. i
# Z ■$/*
P
-Hr mJ I me* / riled ftrE fcffcd
0.5/ 7
5,g*
•Cost per kl* average
d 0.0 X dluwvc
rtEt
15.01 cents
a io.o x
ran
17.67 cnl*
-t-rcereoir storage yfrlLM;
MiKiNui
Mfin
619.2/ MOI
a !2,p i dtacwm;
hc«
21.9% emu
562^25 MW
377.95 KN
Cost   per   HA   wei
ghted
8    8.0    X    d^SCOufit
rice
IB. 49 gernEi
Guaranteed - 100 t
3 ID.D X dlscoi^E rate
23.66 cents
Secondary ■ 50
X
3 12,0 X diggpunt rate
29.38 cent*
Twelve storage voluw
24 U MOM
Regret of rrpufeEion
32/B X
-Energy production per H
CN of in
tlo*
125.7 PMh
-T^rbrrwi
Ergncis
3*
U.6 MU
G#rar*crf eapclty:
MmJm
4|>» •*
Keen
44.56 H
NlnlMJH
3D.96 smrANNEX-4
Out put for
Load flow AnalysisANNEX 4-L
PTi   Interactive    power   SYSTEM
»lKVLATtiX--PSS/'E
HOW, JVM 11
c8f01
POWER SYSTEMS 5-TVdT (ABBAT
PEU LOAD 20Qfl r BASE CASE
ETOROELECTEIC PROJECT)
BUSES WETH VOLTAGE GREATER THAW 1,0506:
- BUS ■   -------- 1   AREA   V(PU)       V(KV)
5   AWAStt2   GIO.5       1   1.0500        11.025
150
OLTDEJl
M3
if 2
GH.MBI
132
I l.Q«0 140-70
1 I.0467 143.46
1 1.0521 69.439
I------------ KVR ----- -------X
IBS        OKEDO        1«
1«1  nEKEKFTE  113
50* AMY O 10.5
AREA V(PU)
1 l.Ottl
1 1.0S09
1 1.0500
V<KV)
1*0.71
11-015
701
ABtlAt
£6-0
BUSES  WITH VOLTAGE   LESS TEAM 0.5500)
I
.—I      AREA V(?LT}      V(KV)           S ---- --------
AREA VfPUl             V(KV>
17 ALEMAYA 45-0 1 0.6503 40.062
If HARER 45-0 1 0-S5B5 40.431
it   CHELEMKO45 .□          1   0-4424            J*.107 20 ElARILB      45.0        1  0.1904           40-067
21 JIJIGA 45-0 1 0,4727 35.271 25 XOKA 45.0 1 0,9079 40.B5S
26 HOD-JO 450 1 0,5659 34.547 27 naxarfth«5.0 I 0.4654 34.959
2S   TIRGALEH45,0              1 0.5407    43.332
29   DTLXJL            45.0         I   0.9096            40.924
33 KAL1TI1 45-0 1 0.461* 39.444 34 AAAKI5P 45.0 1 0.4767 35-450
35 ADDI5SCHJ45-0 1 0,4540 34.521 36 AJtAJtl 43.0 1 0,654? 34.440
37 DUE EM 45.0 1 0-7133 35.201 34 D-IKIT 145,0 1 0.7636 34.352
42 EALLTI3 45-6 1 0-506? 40.100 43 HBFASSIL45-Q 1 0.4774 39-443
44 S-EBETA 45.0 1 Q-1349 33.141 45 GEDJA 45.0 1 0.7193 32.369
46 A. WEST 4S.0 1 0.7053 31-736 47 COTOB1B 45,0 1 0.7319 32.935
CB  A.EAST     45.0              1 0.7171    33-249
so    A UZM
r
45-0              1 0.4546    40.444
42   RARAR     «4<0             1 0.5312    61.592
45 QEFERSA 45.0 1 0-934^ 42.039
51 AMBO 45.0 1 O.R7I0 39.411
67 □ESSIE 44,0 1 Q-9439 62-230
44  WOLD 1A   44.0             1 0-533&    41.431                    73   GHIOH             64.0        1   0.5405          62.073
75   OEFERSA 66.0             1 Q.43S2    61.721                   74     FICU               66.0        1   0.5063            59.414
• 4   5HAKISO    64.0           1 4>9395   61.743                   110   ADI GRAT     44.0        1   0.9449            62.626
140      ADDIS CE 131           1 D.939S    124-05                 143   SOLS              132        1   0.9479          135-13
147  HUGER         132            1 0.9333    11J-L9                 14?    COTOB1E       133        1   0>9497           125.36
334   HARER       15-D            1 0.5015    13.523FT I INTERACTIVE POWER STSTZX SIHVLATOB— F$*/E POWER SYSTEMS STUDY [ASSAY EYDROELECTRl C PROJECT]
PEAR LOAD 2004, BASE CASE
TRAN SHI SSI OX LINE LOADINGS ABOVE 11S.0 1 OF RATING SET
I’"-----FROM BUS- — 1 I—-------------------------------- -TO BUS---------- — -I
BUS        NAME    BSRV  ah ha        BUS         MAKE     BSKV   AREA   CAT KALITI1   45-0            1             J4’   AEU1            45,0          1     1
42        KALITI3   45.0            1            4J<   ME PASSEL45.0            1      1
NOH,. JVM 12 1995 OtiOJ
A-
CVRRENT { NVA }
LOADING RATIMO PERCENT 12.0            190.0
21-9             12.0           740.9ASNE-V
PT1   INTERACTIVE   POWER
POWER SYSTEMS STUDY (AB BAY
PEAK LOAD 2004. RASE CASE
SYSTEM        SIMULATOR--PSS/E HYDROELECTRIC PROJECT)
HOW„ JUN 12 19 95              0 8 s 0 2
TRANSFORMER LOADINGS ABOVE     115,0 * OF RATING SET At
I—’ — FROM RUS------------— -I
BUS-— ——-X
BUS         NAME     ESKV AREA              BUS            NAME      BERV AREA CAT LOADIMG
HV*
RATIHQ PERCENT
25     KORA           <1.0          i            113*   KOKA            132           1      1               17 .9              32.0            149.2
2fi     YIRGALEM45.0
33
RALITI1
45.0
l 171- TlhGALZM J31 1 1 7 rO 8-0 114 .9 138* JLALtTt 132 1 L 27 -2 22 .0 123.6 138* KALITI 132 1 3 31 .4 25.0 121.8
l
33
KALlIII
41.0
l
44
5EBETA
41.0
l
41
COTOBI E
41.0
1
144* fiASLATTA 132 1 1
141* COTOBIE 132 1 1
39.9              12-0            332 6
36.7 12.0 305,9
42*
HARAR
tfc.O
l
334      barer            11.0           1      1                  9.0              fc.O            150.4
138
KALITI
132
l
243*   KALITI         230          1      1
82.4              43.0            130.7
144
SABAT7A
132
i
2J5»   SABATAl        230          1      1            69 - S'
43 .0              148.7
146
GAFARSA
132
i
160
AWASH T
132
i
IS 7
MEKELE
132
i
333*   GAFARSA      230           1      1
24**   AWASH T       230          1      1
241*   MEJCELE      230          1      1
81-0 40.0 201.4
13,8 11.0 125 -7
29.7 20-0 168,3PT I INTERACTIVE POWER SYSTEM EIWULATOR--PSS/ E POWER SYSTEMS STUDY 4 ABBAY BYDROEUECTRIC PROJECT) PEAK LOAD 300 4, BASE CASE
GENERATOR SUMMARY I
HON, JUN 12
ANNEX 4-1 09:01
BUS          HAKE ESWLT fHAC TTP           NN
1   KOKA O 10.5             1       2           34.0
2   AWASR2 010.5          1       2           22.0
)   AMAS33 010.5           1       2           32.0
S   F1NCBA 013.B          1       3           74.9
4  T ABAY G«.OD          1       3             4.0
8   MAKAHA Olli             1       2         153.0
9   INDSEL 6.00              1       4              0.0
10  NEREgNU 6.00       1       4              0.0
11   AMASA G 4.00          1       4              0.0
12   C0MB0L 06.00           1       4             0.0
11   GHIKBl G6.0Q           1       4              0.0
14  ADWA O 4.00             1       4             0.0
IS  ADICRAT 4.00           1       4              0.0
SGI   LANCAM O1D.5        1       2            35.0
502   G-CIBE GlS.B             i       2         iao.0
503   MEKELE G4.00          1       4              0.0
MVAR OKAl QMI* VSCBED VKCTUKL
4.0              31-0        -30.0 10-815 10-ill
-7.4               34.0        -34,0 11.035 11.055
-7.4               36.0        -24.0 11.035 11.035
-IS.2               33.0        -J3.G I*.318 1* JI4
-0-4               7 rO           -4.0         6.180         6.1B0 0-4              10.0        -40,0 14-4*0 18
REN
0,0
0.0             0,0       4.000         4.000
0.0                o.o             0.0        4.000         6.COO 0.0                0.0             0.0 f .000                4.300 o.o                0.0             0.0        6.000         6.3QO
o.o               o+o
0.0        4-000         4.300
0,0
0.0             0.0 4.000 4-000
0,0                o.o             O.o 4-000               4,000
43
t
30-0        -30.0 10,816 10.415
-10-4              40 -0        -9O.0 14,114 14.214
SO4 ABAY G 10.5
SUBSYSTEM TOTALS
1 2 2t.O
Sil.4
0-0
1-•
0-0             0-0       6.000         4.0Q0 35.0        -20,0 11.035 11.025
-23.3            34B-0     -3 37.0           MVAJlASE^
704-7PTl IHTEflACTIVE POWER St STEM <IHVLArOR—P5S/E POWER SYSTEMS STUDY (ABHAT HYDROELECTRIC PROJECT) PEAK LOAD 2004, BASE CASE
HOM, JUM 12
ANNEX 4-5
00:03
SVHHAFtT EOft CQHPLETE ST STEW
SYSTEM SWTHQ B
US SUMMARY
BUS X—-NAME—-X
X—- AREA
—I 1- —
ZONE ---X
NW                MV AR        MVABASE
5 riHClA 013.0
11
)1
(1
19.9
-15.2
105.0
143 BUSES
9 PLANTS
145 BRANCHES               <9 TRANS FORME ftS
9 MACHINES
o ek: lines
I-”- — ACTUAL  ——u""A. a.-----------
NW
502.3
0,0
0,0
NV AR
-23.3
0.0
0.0
MW                   MVAR
FROM GENERATE ON
TO CONSTANT POWER LOAD TO CONSTANT CURRUTT TO CONSTANT ADMITTANCE
TO BUS SHUNT
TO LIMB SJTUTfT
FROM LIMB CHARGING
542.9
-23.3
0.0                         O.0
552.0                     143.1
0.0
0.0
25.3
79.4
<3.0
5»4-f
0.0
0.0
0.0
220.4
25.0
7S.0
0.0                    540.4
VOLTAOB
X---- — LOSSES
----- —I
I— LIME SHUNTS —I
0.0 510.fl
CHARGING
LEVEL BRANCHES
NW
MVAR
MW
NV AR
MV AR
230.0
31
9.27
83.47
0.0
79.4
231-4
132.0
««
12.31
74.10
0.0
0.0
141-4
44.0
39
1.74
7,14
0,0
0.0
17+9
4.3,0
32
7.12
54,>0
Q.Q
0.0
2,4
13,0
3
0.04
1,04
0.0
0-0
0.0
13, fi
1
0.00
O-OS
□ .□
0,0
0.0
19,5
3
0,2#
7-31
0.0
0,0
0.0
TlxTAL
165
30, a*
224.47
0-0
79.1
540-4annex 4^
PTE INTERACTIVE POWER SYSTEM 61KULATOR--PSS/E POWER SYSTEMS STUDY < AB BAY HYDROELECTRIC PROJECT) PtM LOAD 2004, BASE CASE
HON, JUN 12 1995                08:03 SHUNT
SUMMARY
1---------- - BUS ——     — I
NOH           INAL
KW MV AH VOLTAGE
156
KCMBOLCH
112
0.0
0-0
l,gaoo
SWITCHED
161
□ PAW* 1
132
0.0
0-0
1.03O&
SWITCHED
162
D DANA 3
132
0.0
0-0
SWITCHED
169
SHASUMB
132
0.0
0-0
1,011b
SWITCHED
172
HAKISO
132
0.0
0-0
G.IW
SWITCHED
ISO
AKAA MIW
132
OuO
0,0
0, JSSt
SWITCHED
164
AGO ARC
132
0.0
-5-0
1,015?
SWITCHED
its
MUNOBEDL
132
o.o
-5,0
1,006J
SWITCHED
196
ALAKATA
132
0.0
-15.0
i, cm
SWITCHESANNEX 4-7
PTI   INTERACTIVE    POWER   SYSTEM SIMULATOR —PS S/E
MON. JUN 12 19** orio*
POWER SYSTEMS STUDY (ASSAY
LOW LOAD 2004. BASE CASE
HYDROELECTRIC PRO JECT J.
BUSES WITH VOLTAGE GREATER TRAM 1.0500:
I...... pus —------------------- 1
191 NElCEKPTE 132
AREA V<PUJ V(IV}
1 1.0546 139.24
X —— AUS----------------- 1 AREA V(PU) 192 GET I ME I     133         1 1-0*14
V(MV)
140.11
BUSES WITH VOLTAGE     LESS TRAN 0.9500: — BUS —                 AREA V(PV>      VfKIf]
x------
.« BUS -
AREA V(PU)        V[KV)
25 KOKA 45.0 1 0.9331 41.539 26 HOMO 45-0 1 0.9932 40.419
27 NATUREEE45.0 1 0-19*0 40.412 39 DILXA ,5.0 L 0.9453 42-519-
33 KALITT1 <3.0 1 O.?i»3 41.323 34 AKAKISF <5.0 1 Q.9153 41-1*7
IS  ADDESSOU45.0            1 0.H3S1    40.620
36   JUJLKl              45.0              1 0.9040       40.679
37 DUKZM 45,0 1 0-1547 31,507 3» D.EBIT 1*S.O 1 0.H4J7 3?,96B
42  KAL.III2      45.0             1 0-930*   41,491                    43   WEFASSIL45 -0                  1 0.9134      41.1O4
44   5EBETA     45.0             1 0.4347    37.563                    45   GEDJA          45-0              1 0.0333       37.047
45  A.WEST     45.0              I 0,1131    36.619                   47   COTOB1E        45,0                1 0*306       37-329
4B   A.EAST      45,0             1 D.tlOS    34.940
50  R.ALEH          45.0              1 0.9351       42.030
51   AMBO        45,0             1 0.9235    41.557                    66   COMBOLCH66.0                 1 09345        61.67*
47   DESSIE        46.0           1 0.9365    61.14*
6*   WOLD IA       66.0              1 0,9333       60.934
76   FI CEE       66.0             1 0.9453    62.3*9                  140   ADDIS CE 132                    1 0.9491      12$-.29PTI INTERACTIVE POWER SYSTEM S t HULA TOR--PS 5/E POWER SYSTEMS STUDY < AB BAY RYOROELZCTRIC PROJECT) LOW LOAD 2004, BASE CASE
MON, JUN 12 I”*
annex
OB'05
GENERATOR SUMHARTl
BUS       NAME BSVL.T  /MAC  TYP         MW
Ji   KORA 0      10.5         1       2           24-0
2     ANASH2 QliD.5       1       2              lt.0
3       AMASS! 010.5       1       2           20.0
5       FIMCtfA 013-4       1       3           22.9
4        T AAAY 04,00        1       2              9.0
B    MAKANA 013-B       1       2         100.0
9          IND.SIX 4.00       1       4              0.0
10   WEREGWU 4.00       1       4              0.0
11       AMASA 0 6,00       1       4              0.0
12      C0MBCL Gt,00       1       4              0.0
13      G&3MB1 Gt.00       1       4              0.0
14   ADWA       4.00         1       4              0.0
15   AJ5IGRAT 4, DO       1       4              0,0
501     LANGAN 010-5       1       2           35-0
502        G.G1BE Gll.fi       1       2         100.0
503     MEKEUE 06.00        I        4              0.0
MV AR         QHAI              QMIH     viched   YACTUAL
RF.M
-20.4             31-0
-13.7             24-0
-20.5             26-0
-24.0             33.0
-2.4               7-0
-44,3
*0-0
-300         9-975       9.975 -24-0       IO .500   10,500 -24-0       1D.29D   10.290 -33,0       13-662   13.462
-6-0         6.000        t .000 -40-0        13-110   13.110
0.0               0.0                 0,0          4,000       6.000
0.0               0-0                 0,0        4 -000       6.000
0.0              o.o                 o.o          6.000       6-300
0,0              o.o
0.0        4 ,ooa       6,300
0.0
.0                 0.0      6 .DOE)       4.300
0.0               0-0                 0,0         6.00O       6 .000
0.0               0.0                 0.0          6.000        6.000
5.4              30.0               -30.0        10.500     10.500
-40.4              90.0
-90.0        13.110     13.110
0.0               0.0                 0.0         6.000       6.000
504 ABAY 0        10.5
SUBSYSTEM TOTALS
1 2 20.0
350,9
-11.1             25,0
-20.0         9.975        9.975
-207.4           344-0           -337 .0          XVABASE-
7 04-7ANXEX -t-9
Ml INTERACTIVE POWER SYSTEW «IMULAVOR--PSS/E POWER SYSTEH3 STUDY (ABBA? HYDROELECTRIC PROJECT> LOW LOAD JOO 4, EASE CASE
NON   INAL
MON, JUN 12 19»5 OEtOS SHUNT
SUMMA*Y
KVA*      VOLTACE
146
KOMBOLCH
132
0.0
<3.0
0,4540
SWITCHED
Ul
□ DAW A 1
132
0-0
0-0
1.0242
switched
163
D DAWA 3
132
0-0
0.0
1.0731
SWITCHED
16 9
5 R AS « AKE
132
0.0
0.0
0.4966
SWITCHED
172
SHAK.ISO
132
0.0
0.0
0.HM
SWITCHED
ISO
AKDA KIN
133
0.0
0.0
1.0004
SWITCHED
IE4
AGGABO
132
0.0
□ .0
1.0131
SWITCHED
165
BUWOBEDL
132
0.0
0.0
1.0143
SWITCHED
19 6-
AUUHATA
132
0.0
0.0
1.0274
SWITCHEDPT I INTERACTIVE POWER SYSTEM SIMULATOR--PSS/E POWER SYSTEMS SIUDr (ABBAY HYDROELECTRIC PROJECT) LOW LOAD 3004„ BASE CASE
*** ■ '■< «««> « m*i*ii*i r. . NUMMARY FOR COMPLETE SYSTEM
MON. JUN U I”5
00:04
BUS
5
X —-HAKE- — I
FINCHA G13-4
SYSTEM
I------ AREA--------- 1
IS               !
9 PLANTS
SWING BUS
X —- SOME
1I
SUMMARY
-r—J
I
MW
72.9
MV AR     NV ABASE
-24,0
105,0
143 BUSES
145 BRANCHES
<9 TRANSFORMERS
$ MACHINES
0 DC LINES
I--------- — ACTUAL    —--------- X X  ---------- NOMINAL      ------—-X
MW                MV AR
MW                  MV AR
FROM GENERATION
to constant foher load
TO CONSTANT CURRENT
TO CONSTANT ADMITTANCE
TO BCJS  SHUNT
TO LINE      SHUNT
FROM LINE CHARGING
350.9
0-0
0.0
-307.4
0,0
0.0
334.1                     111.5
0.0
0.0
0.0
95,2
0.0                    523,0
3S0.9
0-0
0.0
301*0
0-0
0.0
0.0
-207 - 4
t>.o 0,0
124.4
0.0
90.0
520.4
tlflf 'TTJll.i 3i»
r
i¥
1-- LIME        SHUNTS --X         CHARGING
LEVEL
BRANCHES
MW
MV AR
MW
MV AR
NV AR
230.0
21
4,09
30.55
0,0
95.2
324.4
132.0
44
4-15
37 + 27
0.0
0.0
177-5
44,0
35
0-9*
3*05
U-0
0.0
IB. 1
45-0
32
3-31
22-47
0,0
0.0
3-0
15-0
3
0.02
0-35
0.0
0.0
0.Q
13-ft
1
0.00
0.03
0,0
0.0
0.0
10.5
J
0.34
5.00
□ .0
0.0
0.0
TOTAL
145
H.75
IOS-45
0.0
95-2
523.0ANNEX-5
Hydrological data■I
Hydrological Flow Data
for
Kessie-Bahirdar (MCM)
mr
1171        116-01 1972          77*10
1173           <»'*a 1174            46.10
1175            14-40
J176         174.40
1177          117-04 1174         104,2© 1170            00.50 1040            43.00 1103          134.44 1112          106*10 1103            17.30 1144              34.22
96.74
■ -J/B            14.13
A*SO46J 44- *>•
F«b               M#C 54.71            44.41 41.51            55-44 36,00             16.10 26-54             44.30 12.10             53.10 11-50          110-74 93.44           100.46 54.00            34,5©
40,30             42,46
41.21             47.47
241-50            433-75
53-04             74.53
21.40             44.10
20,70             35.34
44.45            01.40
24.46             34.50
Apr
57,54             02.30 103.50             71.60
11.45             74.14
41-00           161.41
44-4©             43.64
>35*10 151,40 41.15 44*11 13.34 44.60 44.lt 106.51 12.40 41.13
272.57            211.64 15,13           102.53
125-13 217.44
20.30 76.41 44*11 101.42
30,*l
37.47
J0l
340-33         1744.00
107.10         1377,30
114,17         1110.41
176*55        1401.41
214*64         2750.10
110,40         1714.30
■ 4.54        2641.30
02.00         2414.00
101.00         1074.00
147-11         1444.30
274*45         3773.04
17.73           473.14
171.41           613.52
272.42          1416.73
147.10         2024.44 64*74           754.67
Au-}
3"P
5740.50 1*)2.9© 2457.00 474.50
6552.40 1224.20
5953-99 1140.00
7521.10 5©77*1©
4153.20 2212*54
5114.10          2774*44
4)42.30        1714,54
6154.30 1223.50
5030,05 3410.7©
4001,54 2214.2©
210*5© 1331*4©
4047*06 1731*39
1741.11 454.4)
4674.61 2435.71
1745-2) 741*55
Oct              Ba* 4*4.20           217.20
104.10            44.00
411.10          217.10
304-40          215,50
714.30 124.40
4*5.60            35*.*0
744.JO         471.14
771.70          757,30
127.10          141.46
131.10 440.22 421.10 224.42 704.45 134.24 704.10 307,52 120.04 41,35 530.42 344.57 194.42 103.04
0M 140.44
52.Q0
121.44
152.49
247.40 21.10
104.44 166,JO 117*21
244.05 140.DD
40.00
134,17
33-17
134.40
50-01
ToEbI 10051.52 5191.01
11340-51 12412.14-
17257,34 11011.10 12911.44 10154,40
0405.72
12201.04
13271.11
3451.12
♦317.21
472 1.31
10250.77
325.05Hydrological Flow Data for
Abbay-20 (MCM)
*-354* lq
Pt*.
Mir
Jin
J«1
••P
Oat
■or
D*e
AA 20
■3/i
Jin
Fib
M«r
M>r
1.24
3.13
>♦«
4.03
5.74
17,31
125+1*
404,44
121.30
31*93
20.10
13-2*
759.41
24.09
1973
7.25
5-01
7.51
94.41
172-03
47.14
7-41
5.44
3.44
163.34
11.52
1972
9+41
2-11
2.41
1.12
5.25
1.14
132.99
459.47
124.49
34.52
15.20
1.47
791.67
15-10
1972
3-47
2*12
1.13
5,34
1.45
3.24
7+43
10.40
12.34
214.49
414.71
91.20
27.20
15.09
11.47
B6B-.B5
27.55
im
i»ts
4.42
5.90
3+75
3.25
3.15
20.41
192.34
124.41
153.40
10.14
23.00
17.15
1204,01
39.31
1.31
9.11
94.40
1.59
120.00
444.16
154.BB
31.19
25.03
1.47
435.71
24.44
ifi*
12.31
4.*7
4-34
7.44
3 + 43
3-09
4-04
115.47
577.92
194.49
52.24
47.54
13.01
905.74
21.72
1177
1.24
2.33
7.24
4.44
174.12
304.74
120.14
34.02
11.00
11.44
710.54
33.53
1191
7.2*
1-92
2.54
3.14
7.12
11*29
131.11
291.01
15.51
22.95
11-43
B.21
311.40
11.44
im
4-97
4-22
5.01
3.35
3.02
7.50
102-71
352.14
354+35
45-47
31.12
17.29
•54,17
27.01
lioo
4.47
2-01
14+11
19.52
244.11
142.41
155.27
30.05
15.14
9.40
929.01
39-44
1941
9-55
10.47
29.44
19.01
14.74
93.77
49.44
9.55
4 -B9
254*15
0,12
1992
7,47
1.71
5 + 5*
4.44
7.11
4.14
47.12
49.44
21.13
1.03
445.91
20,49
2.44
4.49
1.77
15+35
12.01
41.44
347.49
122.40
im
4.11
2.19
2-32
330.43
10.41
2.4B
3-09
1.73
1.43 -
5.71
19.10
99.17
124.70
40.09
9.02
6*77
4.12
5+73
9.41
7.10
11.73
141-17
327.11
141,10
34.44
19.46
9.19
122*17
54.71
13+74
7.20
1,50
717.55
22.75
ri/B
2.57
1*99
2.14
2.14
3+45
4.53
52.97Hydrological Flow Data
for
Abbay-2I
(MCM)
AB-21
A-4731 «<l
jj-
Jvb
Jal
*■*
••P
Oat
lav
AA-2 1
Yaur
Jli
r*b
J»E
Apr
M*y
141.47
543.37
112.4*
42.44
27**4
17.01
3010-04
32.33
1*71
11.4*
5.14
4.37
3.41
7.74
21.31
43.55
10,43
7.*4
4.0*
407.94
35.47
*.73
4.73
14.0*
121.47
231.44
1»72
7.23
l.*l
1.33
1.51
1.54
7.44
10.13
174.34
415.53
142.0?
40.3*
24.41
11.44
1043.09
33,71
1*13
4.44
2.44
4.41
1J.*7
14.44
130.12
535.44
127.04
34.55
24.24
14.33
1144.74
37.04
1*74
7.**
2.4*
4.35
230.54
704.*4
477.25
47.33
30.0*
1*22*10
51.44
3.44
4.34
4.10
27.4*
im
O.*9
7.7*
f.SS
11.14
11.41
14.21
11-24
141*14
3*7.3*
247.55
42. *3
33.41
23.2*
2,15
1119.44
35-50
1*7*
14.12
n.54
1214.31
30.57
1*77
11-4*
*.?*
10.2*
4.44
4,1*
1.13
24*.43
447.4*
241.17
70.15
43.04
4.5*
4.45
233.41
411.94
141.54
73.54
24.20
15*43
954.14
30.24
1*70
5.79
5.24
3.43
J.13
3*0.14
114.52
30.12
15.30
41.43
794.14
25.OS
4*22
*.W
17.45
174.14
1*7*
*.33
3.47
4.0*
10.47
13*.42
473**4
344.*3
11.11
41.30
23,21
1144.*0
34.37
1*00
4.4*
3.17
4.34
7.74
4.04
204.51
40.35
21.30
13.14
1247.31
3*.54
23.43
15.4*
14.21
334.44
455.40
1*51
12.13
23.31
39.03
7.3*
* *4
*.44
4.25
43.37
1* .7*
325.53
44.44
12.12
4.57
143.90
10.91
1*02
*.*7
4.M
r
43.10
444.50
144.43
44.43
27.03
11.44
447.34
27*54
31*77
70.41
14.13
1903
1.31
2.77
6 .4J
2.7*
2.3*
1**2
7.23
35.43
135.1?
147.45
10.45
12U1
3.09
3.12
443.**
14.4*
1**4
3.5*
4.41
7.4*
7.51
1.53
15-77
1*0.11
419.35
1*0*42
4*.5*
25.04
12.44
*45.57
Main
M»
5.47
4.70
30.55
3.51
4.09
71.13
L44.03
73.47
14.4*
■ -J/B
3.4D
2.4*
2.27
1**1Hydrological Flow Data
for
Abbay-22
(MOM)
AB-2 2
A-5134 SO
r««r
r*b
Ka,
H»r
*P'
«■¥
Jul
*■9
4*P
Oct
Bov
KB 22
ion
32.04
s.io
4.74
5,07
1.39
23*31
101.30
309.41
174-70
44.5)
30.31
19.32
1104.84
35.10
1971
7.*4
4.24
3.41
10.34
7,JO
10.94
140,40
250.71
49.00
10.90
0.57
5-30
51*.49
14.79
19),70
440-34
175.17
59,33
22-13
12.43
3153.57
34.54
1IM
3,06
2.4$
1.44
1.43
7,44
11.04
1974
0.44
2.70
4.72
5.0 0
13.14
11.01
319.40
407,31
139,72
39,44
21,00
13.54
1144.04
40.13
1*75
9.45
1.44
3.4?
4,73
4.45
30,03
2ID.50
747.15
317,84
71.04
11,32
23.20
1)40.24
33.ij
1974
10.IJJ
10.15
12.11
12.04
13.44
12.22
174.04
640.23
215.40
44.47
34.4?
2,44
1114.91
14.33
1977
12.0)
t.S)
11-14
4.H
4.30
0.11
370.23
530.41
211,40
74*12
00.17
19.01
13l9.il
11.05
1IM
ID.43
3.71
3.72
3r4O
4.73
9,38
251.37
444.99
175.29
70.71
14.21
18.94
1011.34
32.91
1979
10.1$
6.IS
4,)9
4.30
10,47
19.37
191.13
824-13
124x70
33.45
14.49
11.94
057.30
13.15
IlflD
6.3i
4.20
8,00
0.4$
4-40
10.9)
149,77
511.15
374.43
93.49
44.90
23.19
1244.31
39.44
1901
11.12
27.49
41-22
27.40
21-39
24,44
304.03
490-93
224.24
4).79
23x12
14.20
1353.40
42.92
1912
10,92
3.41
8.01
9,74
10.44
1,95
40-44
21-47
134.44
72.10
11.91
7.11
373.23
11.84
1901
■ -9D
1,01
4.33
12-77
22.22
17.30
70.64
504.44
170.44
7?.1O
29.33
12.87
941.18
29.14
1*04
3-90
1.03
2.31
2-0»
7.04
27.8)
144,53
101.70
07.54
13.14
4.22
3.34
481.78
13.28
K««n
9-07
7.02
0.34
4.1?
10-34
17.12
2Q6.72
474.79
204,6)
5).12
27.19
13.47
1043.38
Wo
1.6 8
2.90
).I2
3-13
1.16
4.40
77,10
178.01
79x72
10-04
10.49
3.10
11.14ANNEX-6
Composition of the Study
TeamThe Beshilo riv^r Medium scale Hydropower P^a-nts  Development reconr.ausance Study  ws carried out 'under die Government's  emergency  Programme. as  die first phase of studios  to exploit the hydropower potential of die priority siles identified in the Biuc Nile river Basin.
The Project Team consisted of:
Aio Solomon Seyoum
Ato Tcsfayc H/Giorgis(Tcam leader) Ato Wadi AWuiehim
Ato Tcsfoye Wolde
Ato Bcgoscw Abate
Ato Assefa Salih
Ato Abebayehu Alemu Ato Dagne H/Michalc Ato Temesgen Tesema A io H/Mariam Beycnc Ato Teshome Yihuabshet Ato Dejene W/mnriam
A io Alennfc Beycne Ato Luclscged Tadessc Ato Leulscged Tesfaye Ato Lculseged Bekdc Ato Tilahun Asmare Ato Daniel Sime
Ato Hailu Tekelab
A io A marc Negash W/n Meseret Teklu
W/ro Menbere Seyoum W/ro llimt Alemayhu W/rt Rahel Girum
Project Manager, WRDA
Civil Engineer, EELPA
Elec. Engi ncer.EELP A Sanitary Engineer, MNRDEP Geologist, ErGS
Surveyor,, EELPA
Surveyor. EELPA
Surveyor, EELPA
Driver, WRDA
Driver, WRDA
Driver. EEL PA Environmentalist, WRDA Sociologist. MNIWEP Hydrologist, WRDA
Mechanical   Engineer,   EELPA Mechanical Engineer. WRDA Hydrologist, WRDA
Hydrologist. WRDA Drafts Man. WRDA Drafts Man, WRDA Drafts Man, WRDA Secretary. WRDA Secretary, WRDA Secretary, MNRDEP
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ind DivirorrncBfcal I'rcitciuc^ANNEX 7
PROJECT TERMS OF REFERENCEIKEM3 QF.REFERENCE
■ FOR
A g.gCONNAISSANCE STUPI
Q.E
yVLXIPURPOSE MEDIUM HVDROPOWEB SITES (MHPF1
1 Background
Under the Government‘3  Emergency  Program,  to  alleviate the current shortage in power demand,  priority  sites have been identified in the Abbay,  Tekeze,  and Omo  River Basins for subsequent Studies to exploit their hydropower potential.
The sites selected as priority  implementable project,  emanated from desk review of previous studies by  WAPCOs experts during the preparation of the Preliminary  water resources Hester Plan of the country  Except for the sites in the Abbay  River Basin, which are studisd to  reconnaissance level details,  the studies on the Tekeze and Omo  River Basin sites were preliminary  in scope and are thus the subject of a  reconnaissance study though the sites in the Abbay  River basin will be visited to update data and information contained in the previous study.
The proposed studies on th* selected sites will start by
appraisal, verification and upgrading of the previous work by
WAPCOS and the USBR, as appropriate,
2.1 Summary
A        comprehensive        reconnaissance        study        in        the        context        of multipurpose        water        resource        development        project        is        to        be carried     out     to     provide     the     government     with     an     outline     of     short term      potential      developments      and      general      plan      for      the      rivers under       reference,       recommending       priorities       for       development.       Th* reconnaissance study shall, as much as possible be detailed
1and comprehensive and shall be designed to reduce to th*
minimum the chance of subsequent unfavorable prefeasibility
findings. The general scope of work shall include all those
tasks required to perform the preliminary economic assessment
and those that should and in identifying critical issues that
are likely to be important at the pre-feasibi1ity stage.
Collection and review of all available data  pertaining  to  the
sites,             including             topographic,             hydrometeor
logical
,
geotechnical,  environmental,  agricultural,  socio  economic and infrastructural information shall be made.  The study,  in particular, is to include the following fields of activities:*-
General        topographic        surveys        sufficient        to        enable        planning,, layout and reconnaissance level desiqn of project work.
Review and analysis Df water resource and climatic data.
Assessment       of       optimum       utilization       of       rhe       rivers       for       hydro power development and irrigation.
Reconnaissance      level      soil      surveys      and      the      preparation      of      soil and land capability classification maps.
Agro-socio-econotnic surveys to  determine the existing  and future conditions of both the indigenous rural population and to identify possible beneficiaries.
Transportation aurvey  inoluding  inspection of existing  road end connections,  determination of preliminary  layout end internal route..  study  of integrated national programs and recommendations for improvement.
2Potential sites to  be delineated on aerial photographs and maps.  Potential dam sites are to  be located for a  more detailed examination.
Determination     of     the     present     and     future     roles     of     each     of     the resources of the area,
A     general     study     of     the     ecology     of     the     area,     including     plants and animals,
Evaluate       on       general       terms       benefits       and       returns       of       project development.
The     study     will     generally     include,     but     not     necessarily     be     limited     to the following itemsl-
3,3      TQPOflTMrtiiG. Studies
Field survey  of cross sections at possible sites of hydraulic Structures resulting  in mapping  at i;5000  with 5  or 10m contours.
Identify the need for additional topographic mapping.
2.3      Hydrometeorfilpfly
Eeview and synthesis of existing hydrometeor logical data.
Assess      requirements      of      additional      weather      recording      and      stream flow measurement stations at selected sites on the rivers.
Assess sediment load and quality of water
3Assessment     of     the     present     water     use     in     the     basin     both     upstream and downstream of the proposed sites.
Estimate        of        ultimate        water        potential        for        hydropower        and irrigation.
Delineation     of     potential     dam     and     power     plant     sites     on     maps     and aerial photographs and estimation of potential capacities,.
2.4       Geoloqy and Geotechnics
Make surface reconnaissance to  enable inferences to  be made on depth of alluviums,  tectonic features,  availability  of construction materials,  pervious formation and slope stability at dam site and reservoir area, water ways and power houses.
Preliminary           geological           and           geotechnical           investigation           of
dameites and other major structures. w -
2 5 Kngineerinq studies
--
Prepare preliminary  engineering  plans with consideration of several project layouts,  including  variation of dam axis location,  waterway  alignment and off take structures for integration of project plans into  long  term development perspectives of the country.
Conduct         general         investigation         on         reservoir         sites         and         on construction material of dams.
Draw up general plans for land development proposals.
Assess availability of ground
water resources,identify  all potential hydropower sites.  Preliminary  design, analysis and utilization proposals o£  this energy  within and outside the Eegion have to be presented-
Identify transmission line routes 0P appropriate maps.
Carryout         electrical         systems         studies         in         the         context         of interconnected system.
identify      competing      interests      between      power      and      irrigation      and thereby establish optional water utilisation*
propose       layout       plans       for       access       requirements       both       to       and within the project areas.
All plans for identified projects will have to  be presented ID sufficient details to  enable indicative cost estimates to  be prepared.
«
Utilization
A         reconnaissance         level         soil         and         land         classification         of potential irrigable areas.
Presentation of results Shall be toy  means Of standard narrative soil surv&y  and land classification report which will include soil maps and land classification maps tc denote their capability  and production potentials under sustained agricultural u&e and their suitability  for crops and livestock production,  Pertinent data  from field observation and laboratory tests will have to be included in th* report.Review existing  Land use pattern and recommend a  general land utilization,  system,  including  forests,  wild life*  crop cultivation and livestock production with the area-
2.7      Agricultural Development Studies
Potential irrigable lands in the area  will have to  be inventoried,  examined and agricultural development plans to  be drawn up accordingly<
A     broad     consumptive     use     and     irrigation     system     efficiency     is     to be investigated and methods of irrigation to bo recommended.
Types     of     cash     crops     and     food     crops     suitable     for     the     project areas are to be selected.
Proposals           on           recommended           agricultural           practices,           land preparation and cultural practices is to ba made.
Types and methods of livestock production suitable fot the project areas is to  be surveyed and investigations made for marketing of the produce.
Expected       yield,       agricultural       development       costs       as       related       tc values of crops and crop production are to be made.
Requirement for necessary  agricultural experiment station at suitable locations and extension services within the area  is to be examined and recommendations made accordingly.
Studies of market outlet and proposals far establishment of agro-industrial processing  plants at suitable locations will be made.
6Proposals      to      be      made      on      the      organizational      and      management practices to be adopted for each development project.
2.8      E n v i ronmental _.S tudy
A      general     ecological     study     shall     be     carried     out     to     determine the       possible       impact       of       the       project       development       on       the environment,     including     the     fauna     and     flora,     of     the     area.     The scope       of       the       study       shall       include,       but       not       necessarily       be limited to:-
A        general        survey        and        qualitative        evaluation        of        potential problems due to erosion in upstream river basin, and a general
survey  of alterations tD aquatic biotar dangers to  health,  to be expected in the project area  as a  result of projects development impact and recommendation for control.
Collect sufficient agronomic and demographic information to permit quantification of area  of agricultural land inundated and number of families or persons to  be resettled,  where appropriate.
2.9      Accessibility to Sitp
Accessibility  to  the project and construction site and transportation of electromechanical equipment as well as construction materials shall be reviewed- Any  limitations shall be identified.  Remedies and improvements required shall be suggested.
72.10    Socio-Economic_studiec
Review       all       pertinent       economic       factors       and       perform       economic analysis.
With the indicative cost estimates for the identified projects; using  input/output data,  estimate the approximate benefit/ cost ratio for each project.
The impact of project development on the people within and in the vicinity  of the area  and a  general proposal for integration or resettlement of any displaced persons.
3, Human Power
Human      Power      requirement      to      execute      the      studies      stipulated      in the above Terms of Reference is as followsl-
Project Manager
2. 1
3. I
5.  3
Administrative & Finance Officer
Accountant
Auditor
Senior Geologist
Senior Hydrologist
7. 
3
8. 
3
9. 
3
10. 
3
11. 
3
12, 3 13. 
3
14. 
3
15. 
3
16. 
3
Civil Engineer
Senior Electrical Engineer Senior Mechanical Engineer Senior Sociologist
Senior Soils Expert Senior Agronomist Senior Environmentalist Senior Economist Senior Surveyor
Junior Surveyor3          Draftsmen
J           Senior     SOILS Technician
3          Junior     soils Technician
3           Senior Hydrology Technician
3         Junior     Hydrologist
3         Senior        Secretary
3         Secretary
9         Drivers
miscellaneous (Guirds  Errands, Cleaners etc.)
r
9I
I
I
I
1
I
1
1
1
1
1
i 1
J
1
1
I

Summery

Beshilo Hydroelectric Project Summary

Beshilo Hydroelectric Reconnaissance Study Report Summary

Prepared by: Water Resources Development Authority, Ethiopia

Date: August 1995

1. Project Overview

The Beshilo Hydroelectric Project is part of Ethiopia's Medium Scale Hydropower Development (MSHD) program, focusing on sites with capacities of 40-60 MW. Three potential sites were investigated along the Beshilo River, a tributary of the Blue Nile:

Site	Location (Coordinates)	Drainage Area (km²)	Mean Annual Flow (m³/s)
Abbay-20	11°24'23"N, 39°02'15"E	3,548	22.75
Abbay-21	11°22'37"N, 38°53'37"E	4,728	30.56
Abbay-22	11°25'35"N, 38°42'36"E	5,136	33.16

The study was conducted to address Ethiopia's acute power shortage, with only about 370 MW (less than 1%) of the estimated 15,000-30,000 MW hydropower potential being exploited by 1995.

2. Key Findings by Site

Abbay-20

Dam Type: Concrete-faced rockfill
Height: 92m
Installed Capacity: 29.5 MW (2 Francis turbines)
Annual Energy: 86.3 GWh
Reservoir: 550.64 MCM at max level
Key Challenge: Fault lines near dam site (Fault-A and Fault-B)
Construction Materials: Basalt quarry available 6km upstream

Abbay-21

Dam Type: Concrete gravity
Height: 92m
Installed Capacity: 38.9 MW (2 Francis turbines)
Annual Energy: 118 GWh
Reservoir: 1,057.97 MCM at max level
Key Challenge: Fault 500m downstream of dam
Construction Materials: No nearby quarry site

Abbay-22

Dam Type: Concrete gravity
Height: 92m
Installed Capacity: 44.56 MW (3 Francis turbines)
Annual Energy: 130 GWh
Reservoir: 600.87 MCM at max level
Key Challenge: Thin basalt layers within thick tuff/ash
Construction Materials: Would require hauling from 36km away

3. Comparative Evaluation

Criteria	Abbay-20	Abbay-21	Abbay-22
Project Cost (million USD)	171.1	273.9	229.3
Unit Energy Cost (US cents/kWh)	30.5	31.4	17.67
Access Road Length (km)	118	123	170
Land Inundated (ha)	850	1,623	1,033
Environmental Impact	Moderate	Moderate	Moderate

Overall Recommendation: Abbay-20 is considered the most feasible option for immediate implementation due to better accessibility and available construction materials, despite geological challenges with fault lines.

4. Key Challenges

Geological: Highly weathered basalt, tuff and ash formations; fault lines at Abbay-20; potential reservoir leakage
Hydrological: Ungauged river with high sediment load expected (10-25% of storage as dead storage provision)
Access: Extremely difficult terrain requiring helicopter access during survey
Environmental: Loss of agricultural land along river banks, potential malaria increase
Social: Displacement of farmers using river banks for seasonal cultivation

5. Recommendations

Immediate Next Steps:

Conduct detailed topographic surveys with 1:50,000 scale mapping
Perform comprehensive geological investigations including:
- Slope stability analysis
- Reservoir sedimentation studies
- Permeability tests for water tightness
- Fault zone investigations
Establish hydrological monitoring stations on Beshilo River
Conduct detailed Environmental Impact Assessment
Improve access roads for further studies

Long-Term Development Strategy:

Consider cascaded development of Abbay-20 followed by Abbay-22 to optimize infrastructure use, pending results of further studies.

6. Project Benefits

Address Ethiopia's acute power shortage (forecasted to begin in 1995)
Provide renewable energy to support regional development
Potential flood protection benefits downstream
Employment opportunities during construction and operation
Infrastructure development (roads, possibly schools and clinics) in remote area

The project aligns with Ethiopia's national priority to develop its hydropower potential to support economic growth and reduce reliance on biomass fuels (90% of energy consumption) and imported diesel (10% of electric generation).