This document provides an overview of dams in Ethiopia, including: 1) Ethiopia has significant water resources potential but development has been low, with less than 10% of irrigation and hydropower potential developed. 2) There are over 50 large dams existing in Ethiopia, which were built mainly for hydropower, irrigation, and water supply. However, many microdams experience problems like seepage, sedimentation, and structural failures. 3) Several large dams are under construction, including Gibe III, the largest, which will provide 1870 MW of hydropower once completed. 4) While dams provide benefits, they can also negatively impact the environment through issues like reservoir sedimentation reducing storage

1. Solomon B. Gebre
Project Manger
Design of (four) dams in Lake Tana Sub-
basin Project
Potential & Experience of Dams
in Ethiopia

2. Outline of the Presentation
• Country Background
• Water Resources
• Potential & Status of Development
– Irrigation
– Hydropower
– Water Supply
• Existing dams
– Lessons To be Learnt (Two Case Studies)
• Dams under construction
• Future for dams
– Local Context
– Regional Context

3. Country Background
• One of the 10 Nile Riparian Countries
• Population - 72.4 Million in 2004
• Growth rate - 2.3 % per annum
• Population by 2016 – 96 Million
• Total Land Area - 1.104 x 10^6 Km2
• Socio-economy
– Agriculture is the dominant sector
– Largest Livestock population in Africa
– Per Capita income 90 -100 USD
– Water Supply coverage ca.35 %
– Electricity coverage ca.

4. Water Resources
• 12 River Basins
• Total Surface water
Potential of 122 BCM
• Renewable ground water
Potential of 2.6 BCM
• About 97% of the surface
water drains to
neighbouring countries
• Water Tower
• Contribution to Nile Water
ca. 86 %
ABBA Y
AW AS H
WABI S HEBELE
GENA LE DAW A
TEK EZE
OGADEN
OMO GIBE
DE NAKIL
BARO AK OB O
RIFT VALLY
AYSHA
MEREB GASH
Sudan
Djibouti
Eritrea
Somalia
Kenya
Sudan
Somalia

5. Primary x-ics of Water Resources
• Extreme interannual &
Intra-annual variability
– Droughts
– 19 periods of widespread &
severe food shortages in the
past 100 yrs alone
• Spatial variability of rain
flow
– Rainfall mainly in the
highlands
– Lowlands are arid to semi-
arid
• International nature of its
most significant water
resources

6. Potential & Status of WR Development
• Hydropower
– Pot. Economical - 160 GWh or
30,000 MW
– Developed: ca. 800 MW
– < 3 %
• Irrigation
– Pot. Economical – 2.7 Million ha
– Developed: ca. 290,000 ha
– ~ 10.8 %
• Water Supply coverage
(Recent estimate by the MoWR)
– Overall – 47 %
– Urban – 80 %
– Rural - 41 %

7. Justification for Dams
• Low level of development
– Food security of its peoples
– Access to Safe drinking water supply
– Access to affordable electricity supplies
• Resources of the country (Land, Water, Labour)
• Water resources are highly variable (spatially and
temporally)
• Dams are required to safeguard its people against
the ill-effects of recurrent drought and bring about
development
• Regional development – specially by tapping the
country’s huge Hydropower Resources for the
regional market

8. Existing dams
FAO - Aquastat Database 2006
10 Large dams
Author’s compilation from
various sources
> 50 Large dams ( According to
ICOLD Classification (2003))
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ORO M IA
Afar
Som ali R egion
AMH AR A
TIGR AY
SOU TH ERN R EGION
BENISH AN GU L-G UM
GAM BELLA
DIR E D AW A
HAR AR I
AD D IS A BE BA
Sudan
Djibouti
Eritrea
Somalia
Kenya
Sudan
Somalia
400 0 400 800 Kilometers
#
S Under construction dams
%
U Existing Dams
N
greater than 15 m in height from base to crest, or
storage capacity exceeding 3 million cubic
meters for heights between 5 and 15 m

9. N° Name of dam Major basin
Yr.
Completed
Height
(m)
Initial
Capacity
(x10^3
CM)
Purpose
1 Abasamuel* Awash 1939 22.00 65 000 HP
2 Alwero** Baro Akobo 1995 16.00 74 600 IRR
3 Angereb Tekeze 1991 34.00 5 300 WS
4 Dire Awash 1999 46.00 19 000 WS
5 Finchaa Blue Nile 1973 25.00 650 000 HP,IRR
6 Gafarsa Awash 1955 17.00 7 000 WS
7 Gilgel Gibe Omo-Gibe 2004 41.00 839 000 HP
8 Koka Awash 1960 42.00 1 860 000 HP,IRR,FP
9 Legadadi (Main) Awash 1979 40.00 38 000 WS
10 Legadadi (Subsidiary) Awash 1979 22.00 4 000 WS
11 Melka Wakena Wabeshebele 1988 40.00 750 000 HP
12 Midimar Tekeze 1996 33.00 10 000 WS
Important Large Dams in Ethiopia
* Inoperative since 1970
** Only the dam construction has been completed
CM: Cubic Meters
HP-Hydropower, IRR-Irrigation
WS-Water Supply, FP-Flood Protection
13 Chara Chara Blue Nile 1996 9 9,100,000 Regulation

10. Microdams
• Small dams (micro-dams)
constructed for irrigation
supply are concentrated in
the Northern Amhara and
Tigray regional states.
• Construction took place
b/n 1995 – 2000
• 64 Dams in Tigrai Region
– 28 are large dams according
to ICOLD classification
• 14 dams in Amhara Region
– 12 are large dams according
to ICOLD
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ORO M IA
Afar
Som ali R egion
AMH AR A
TIGR AY
SOU TH ERN R EGION
BENISH AN GU L-G UM
GAM BELLA
DIR E D AW A
HAR AR I
AD D IS A BE BA
Sudan
Djibouti
Eritrea
Somalia
Kenya
Sudan
Somalia
400 0 400 800 Kilometers
#
S Under construction dam
%
U Existing Dams
N

11. Performance of the Microdams
• According to a study in
2003 (VLIR), out of the
64 microdams in Tigrai
– Only 18 dams had no
problems
– 24 dams have seepage
problem
– Nine dams have
sedimentation problems
– 13 dams have both
sedimentation &
seepage problems
• According to a study in 2006
(Tefera B.), out of the 14
microdams in Amhara
– Only one of the 14 dams is
functioning according to the plan
of implementation
– hydraulic problems (16.7%),
– hydrological problems (41.7%),
– sedimentation problems (33.3%),
– seepage failures (58.3%), and
– structural failures (8.3%).

12. • Damaged spillway
(Hydraulic failure)
• Syphon used to offtake
water b/c of clogging of
the intake

16. Common Problems encountered in Microdams
Common problems identified include:
• Overtopping due to inadequate spillway capacity – flood
estimation problem
• Seepage through foundation, abutments and reservoir area –
site selection problem
• Cracking or structural failure – geotechnical problem
• Less inflow in the reservoir – hydrological analysis problem
• Sedimentation- design problem and lack of watershed Mgt.
• Lack of proper maintenance and rehabilitation work
• The rush in implementation without adequate investigation in
all aspects
Problems identified should give a good lesson for future building
of similar dams.

17. Dams under construction
N° Name of dam River basin
Expected
year of
completion
Dam
Ht.
(m) Purpose
1 Tendaho Awash 2008 40
Irrigation of ca.
60,000ha
2 Kesem Awash 2008 90
Irrigation of ca.
20,000 ha
3 Koga Abbay 2007 21
Irrigation of ca.
7000 ha
4 Tekeze Tekeze 2011 185
Hydropower of
300 MW,
irrigation d/s of
60,000 ha
5 Gilgel Gibe II Omo-Gibe 2008 21
Hydropower of
420 MW
6 Gibe III* 2011 240
Omo-Gibe
Hydropower of
1870 MW
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ORO M IA
Afar
Som ali R egion
AMH AR A
TIGR AY
SOU TH ERN R EGION
BENISH AN GU L-G UM
GAM BELLA
DIR E D AW A
HAR AR I
AD D IS A BE BA
Sudan
Djibouti
Eritrea
Somalia
Kenya
Sudan
Somalia
400 0 400 800 Kilometers
#
S Under construction dam
%
U Existing Dams
N
* Construction to begin soon

18. Dams Under Construction
Koga Dam
• Basin : Blue Nile
• Purpose: Irrigation Ca. 7000ha
• Project includes integrated WSM
on 22,000ha
• Dam height 21m
• Embankment Dam
• Reservoir storage ~
• Reservoir area ~ 1400 ha
• Financed by AfDB

19. Dams under construction cont’d
• Basin : Awash
• Multipurpose dam
• Dam ht. 90m
• Embankment Dam
• Irrigation 20 – 30,000 ha of
sugar cane
• Hydropower – under study
• Problems due to faults and
artesian hot spring at dam
foundation
• Financed by ETH. Gov’t
Kesem Dam

20. Dams under construction Cont’d
• Basin : Awash
• Irrigation dam
• Dam ht. 40m
• Embankment Dam
• Reservoir storage 1.86 BCM
• Irrigation 60,000 ha of sugar
cane
• Financed by Eth. Gov’t
• When Kesem & Tendaho
Projects start operation –
sugar production will
increase fivefold
Tendaho Dam

21. Dams versus the Environment
Impact of Environment on Dams
• Reservoir sedimentation
due to land degradation
• Nutrient accumulation
Impact of dams on the Environment
• Physical, biological and
socio-economic impacts of
dams

22. Koka Dam – Reservoir Sedimentation & Its
Impacts (Eyasu E. 2003)
• Sediment deposited in the reservoir
(over the past 40 years) = 494 Mm3
• Average annual sedimentation rate = 12 Mm3
or 2115 t/km2
• Loss of storage volume from designed storage
capacity:
a) Designed storage capacity = 1,667 Mm3
b) Current storage volume = 1,186 Mm3
c) Loss of storage volume = 481 Mm3
•

23. • Loss of power generation capacity:
c) Energy equivalent of per m3 of water = 0.266 KWh
d) Energy equivalent of 481 Mm3 of lost volume =
128 Million KWh
e) Price per KWh = 0.473 Eth. Birr
f) Total money value of lost power generation
capacity:
128 X 106 KWh X 0.473 Eth. Birr/KWh = 60.5 Million
Birr or 7.5 Million USD
Other secondary but important impacts are:
• loss of Reservoir capacity to regulate water supply
for irrigation and flood control services downstream.

24. Experience from Gilgel Gibe Dam
• found on the Gibe River in the Omo-
Gibe River basin
• built for the purpose of hydropower.
• Rock fill dam with bituminous
upstream facing
• Maximum height of 41m with a total
storage capacity of 91 MCM
• The generation capacity of the plant
is 184 MW (three 61.3MW units);
• Firm capacity 640GWH
• started in 1997
• commissioned in 2004.
• financed by the World Bank & the
Government of Ethiopia.
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ORO M IA
Afar
Som ali R egion
AMH AR A
TIGR AY
SOU TH ERN R EGION
BENISH AN GU L-G UM
GAM BELLA
DIR E D AW A
HAR AR I
AD D IS A BE BA
Sudan
Djibouti
Eritrea
Somalia
Kenya
Sudan
Somalia
400 0 400 800 Kilometers
#
S Under construction dam
%
U Existing Dams
N

25. • Category "A" Environmental Impact Classification due to
some major environmental and social issues
• the involuntary resettlement of 706 households (ca. 5,000
people);
• loss of 300 ha of riparian forest for wildlife
• altered downstream flow of 16 km of the Gilgel Gibe river,
• and increased habitat for water-borne disease vectors
• resettlement was completed two years ahead of
impounding, 4 years ahead of completion of civil works.
• resettlement cost was estimated at US$4,600 per
household

26. post-resettlement assessments carried out in Dec. 2005
• the resettlement program was indeed carried out according to
the RAP in line with World Bank Guidelines
• Positive Indicators:
– the quality of the new houses is superior to the old houses
– walking distance to health centers as well as schools has
been considerably reduced
• Underperformance indicators:
– the average yield level for all types of crops has been
reduced by 54%,
– the number of livestock owned by the resettled household
has been reduce by 72%
– social infrastructure such as schools, health clinics, and water
points are in poor condition and in need of immediate
maintenance

27. • In spite of some underperformance, all indications
point to the fact that the PAPs are better off now
than prior to the resettlement effort
• This has shown that with proper planning and
implementation, it is possible to develop strong
resettlement efforts
• In resettlement matters, this project was the first one
in the history of Ethiopia to carry a constitutional
resettlement under the New Constitution
• The Bank has also acknowledged (June 2001) the
project as good practice.
Conclusions Drawn from The Post-Resettlement
Assessment

28. Planned dams
• At present, the feasibility study and detail design of at least
12 large dams for irrigation development in four river
basins is underway
• When implemented, these dams will have a potential to
irrigate well over 150,000 ha
• MoWR has planned at least 20 power projects involving
large dams with an aggregated power generation capacity
of over 10000 MW which are at various levels of study
• Four of these projects involve the construction of large
dams on the main Blue Nile River.
• When implemented, these projects will enable Ethiopia to
export environmentally friendly power to its neighbors and
Nile Basin riparian countries.

29. Regional projects under NBI
• Projects accepted by the NBI Council of
Ministers consist of 4 hydropower and 4
irrigation projects
Total 176,000 ha Total 2481 MW
Involves 6 large dams Involves 7 large dams

30. Dams in Lake Tana Sub-basin

31. IN CONCLUSION
• Ethiopia’s Path to Survival & Development
Depends to a large extent on
• Developing available resources (Land, Water &
Labour)
Which requires
• Investing in Water Infrastructure
where
• Dams are at the heart of this investment
However
• Good governance of dams is a pre-requisite for
sustainable development