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%).
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
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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
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
