Trans-Boundary Surface Water Resources of Ethiopia

Water resources of Ethiopia Ethiopia is one of those countries who is blessed with Water resources. Ethiopia covers a land area of 1.13 million km2, of which 99.3 percent is a land area and the remaining 0.7 percent is covered with water bodies of lakes (MOWR 2002). There are 12 river basins with an annual runoff volume of 122 billion m3 of water and an estimated 2.6 - 6.5 billion m3 of ground water potential, which makes an average of 1575 m3 of physically available water per person per year

Climatology of Ethiopia Based on Global Precipitation Climatology Centre (GPCC http://gpcc.dwd.de) data, the mean annual rainfall is 812.4 mm, minimum of 91 mm maximum of 2,122 mm; highest rainfall ranging from 1,600–2,122 mm lowest rainfall ranging from 91-600 mm The mean annual temperature is 22.2 0C The lowest temperature ranges from 4-15 0C highest mean temperature is 31 0C in the lowlands at the Denakil Depresion. highest rainfall ranging from 1,600–2,122 in the highlands of the western part of the country, and a lowest rainfall from 91-600 mm in the eastern lowlands of the country The lowest temperature ranges from 4-15 degrees celcius in the highlands, and the highest mean temperature is 31 degree celcuis in the lowlands at the Denakil Depresion.

Annual rainfall distribution in Ethiopia.

Annual temperature distribution in Ethiopia

Surface Water Resources: Lakes and Reservoirs Ethiopia has 11 fresh and 9 saline lakes, 4 crater lakes and over 12 major swamps or wetlands(surface area is about 7,500 km2). Majority of the lakes are found in the Rift Valley Basin and are rich in fish. Most of the lakes except Ziway, Tana, Langano, Abbaya and Chamo have no surface water outlets(endhoric). Lakes Shala and Abiyata have high concentrations of chemicals and Abiyatais currently exploited for production of soda ash.

A map showing the major river basins in Ethiopia. ABBAY AWASH AYISHA BARO AKOBO DENAKIL GENALE DAWA OGADEN OMO GIBE MEREB GASH RIFT VALLEY TEKEZE WABI SHEBELE Out of these twelve five are the main trans-boundary rivers.

Irrigation and hydropower potential of river basins.

The Nile Basin The Nile system drains a watershed area of 3,030,300 square kilometres, constituting approximately 10% of all of Africa. It is also the longest river in the world, running for 6,650km. Up to 70% of of the Nile's 84 billion cubic meters (at Aswan) comes from the Blue Nile system during its flood season

The Nile Basin Countries Challenges Opportunities Burundi D.R. Congo Egypt Eritrea Ethiopia Kenya Rwanda Sudan Tanzania Uganda (water) stressed system Drought Flood risk Environmental degradation Poor coverage of water supply and sanitation Food insecurity Power shortage Opportunities Untapped potential for energy and food production Political will for cooperation International support

The two main river systems that feed the Nile are The Nile Basin The two main river systems that feed the Nile are White Nile, with its sources on the Equatorial Lake Plateau (Burundi, Rwanda, Tanzania, Kenya, Democratic Republic of the Congo and Uganda) The Baro-Akobo-Sobat system that originates in the foothills of southwest Ethiopia, and the Blue Nile, with its sources in the Ethiopian highlands.

Eastern Nile Riparian countries include Ethiopia, Sudan South Sudan , Egypt, and a small portion of Eritrea  (about 3,500 km2)   constitutes over 60% of  the area of the Nile River Basin but contributes about 86% of the average annual flow  of the main Nile River, about 84 Bm3 at the Aswan High Dam in southern Egypt.  

Blue Nile Sub basin The Blue Nile (or Abbay as it is known in Ethiopia), with an area of over 310,000 km2 originates in the highlands of the Ethiopian plateau. It begins its long journey to the Main Nile from Laka Tana that is fed by the Gilgil Abbay (the little Abbay, believed to be the start of the Blue Nile system), Megech, Ribb and Gumera rivers. The Blue Nile River flows out of Lake Tana and through a deep gorge dropping from about 4000 masl to 400 masl on its journey to Khartoum.

The Abbay River Basin The Abbay River basin lies in the west of Ethiopia It drains towards Sudan on its western border and shares common boundaries with the Tekeze basin to the north, Awash basin to the east & southeast, Omo-Ghibe basin to the south Baro-Akobo basin to the west. Abbay river basin has a catchment area of 199,812 km2, covering parts of Amhara, Oromia and Benishangul-Gumuz regional states.

Abbay basin and its mouth in sudan It has the major sub-basins of Anger, Beles, Dabus, Debre-Markos, Didesa, Dindir/Rahid, Fincha, Guder, Jemma, Lake Tana, Mota, and Muger

Ctd.. The Tis Abbay falls and Lake Tana are located in the routes of this river. Lake Tana The Tis Abbay Falls

Existing and potential developments that indicate the need for collaboration between the countries

Tekeze-Setit-Atbara sub-basin The Tekeze-Setit-Atbara sub-basin (covering about 230,000 km2) consists of the Tekeze river (known as the Setit in Sudan), and its tributaries, the Goang (Atbara in Sudan) and Angereb, all of which originate in the north central highland plateau of Ethiopia. As the river makes its 1325 km journey, it falls from a height of about 3000 masl near its origin to about 500 masl when it joins the main Nile in Sudan, about 285 km downstream of Khartoum.

Tekeze-Setit-Atbara sub-basin The Khasham-el-Girba Dam, a 1.3 Bm³ reservoir built in 1964 in Sudan. It has an installed power capacity of 12.5 MW and feeds the 150,000 ha New Halfa Scheme and a 22,500 ha New Halfa sugar scheme. Recently, another hydropower dam (the 400 MW Tekeze or TK5) has been commissioned in Ethiopia on the main stem of the Tekeze River. There are also a number of small dams in the basin, primarily built for watershed management purposes. Tekeze Dam.

Tekeze River Basin Has an area of 82,350 Km2, covering parts of the Amhara and Tigray regional states. There are two main tributaries (Angereb and Goang) It rises in the central highlands of Ethiopia, and joins the Atbarah River, the lower course of which is a tributary of the Nile. The river basin has a lowest elevation of 536 m and a highest elevation of 4517 m.

Tekeze River Basin The total mean annual flow from the river basins is estimated to be 8.2 BMC. The amount of rainfall varies considerably ranging from 1300 mm in the Seimen Mountain to 600 mm in the lowland areas. The quality of surface water is suitable for irrigation. Tekeze basin has a potential for three large-scale irrigation sites with an estimated potential irrigable area of 83,368 hectares.

Tekeze in Ethiopia flowing in to Sudan

The Baro-Akobo-Sobat Covering about 180,000 km2, consists of the Baro river (and its tributaries such as the Birbir) and the Akobo river (with its main tributary, the Pibor). After the confluence of the Baro and Akobo, the river is called Sobat in Sudan. The river makes its way from an altitude of over 3000 masl in the Ethiopian hills to about 400 masl when the Sobat crosses into Sudan on the way to its junction with the outflow from the Sudd wetlands that buffer the outflows from the Nile Equatorial Region.

The Baro-Akobo-Sobat Alewero reservoir in the upper course of the Baro watershed in Ethiopia, and the Jebel Aulia reservoir at the mouth of the WN in the Sudan are the two dams/reservoirs existing in the sub basin. The Alewero reservoir was initially built for irrigation purposes with initially planned command area of 10400 ha Upstream of the Jebel Aulia reservoir, pump abstractions for irrigation is currently under operation. Development is both at large and small scale levels including public/government and private holdings. Assalaya & Kenana sugar schemes with a total command area of 80,144 ha (16613 ha & 63531 ha respectively).

Baro Akobo The Baro-Akobo Basin lies in the southwest of Ethiopia The basin area is about 76,000 km2 and is bordered by the Sudan in the west, northwest and southwest, Abbay and Omo-Ghibe Basins in the east. About 31% of the basin falls in Oromiya, 9.8% in Benshangul-Gumuz, 24.6% in SNNRP and 34.3% in Gambela. The lower basin accounts for about 42% of the basin area.

Baro-Akobo flowing in to sudan

Wabi shebele The Wabi Shebele river basin, is a transboundary river basin shared between Ethiopia and Somalia. It springs from the Bale mountain ranges of the Galama and the Ahmar about 4000 m above mean sea level and drains into Indian ocean crossing Somalia About 72% of the catchment(202,220 square kilometres) is lying in Ethiopia.

The Wabi shebele in Ethiopia flowing in to Somalia

Omo Ghibe River Basin The Omo-Ghibe river basin has an area of 79,000 Km2, covering parts of the SNNPR and Oromia. The total mean annual flow from the river basin is estimated at about 16.6 BMC In terms of hydropower development potential it is the second largest, and it is a basin in which most of the current hydropower development is taking place.

Omo Ghibe River Basin Large-scale and medium-scale irrigation potential are identified in the basin, with an estimated irrigable area of 57,900 and 10,028 hectares respectively, and a total irrigable area of 67,928 hectares (MoWR data). The basin is also endowed with a variety of wildlife; with Omo and Mago parks being located in the basin, its tourism potential will be further exploited as infrastructure develops in the area.

Omo-Ghibe in Ethiopia flowing in to Keniya and sudan

Genale Dawa River Basin Genale Dawa river basin has an area of 171,042 Km2, covering parts of Oromia, SSNRP, and Somali regions. It is the third largest river basin, after Wabi Shebelle and Abbay river basins. The river basin has a lowest elevation of 171 m and a highest elevation of 4385 m. The total mean annual flow from the river basins is estimated at about 5.8 BMC. The basin falls mainly in the arid and semi-arid zone and is generally drought-prone with erratic rainfall.

Genale Dawa in Ethiopia flowing in to Keniya and somalia

Rift Valley Basin The Rift Valley basin has an area of 52,739 Km2, covering parts of the Oromia, SNNPR regions. The total mean annual flow from the river basins is estimated at about 5.6 BMC.

Rift Valley Basin Large-scale irrigation potential is estimated at 45,700 hectares with an estimated total irrigable area of 139,300 hectares. The basin is endowed with a number of lakes of varying size with high environmental significance. An integrated development master plan preparation for the basin is currently in progress and more reliable data could emerge in the near future.

Rift Valley Basin

Reference Eastern Nile State of the basin report and Eatern Nile Atlas, ENTRO(Eastern Nile Technical Regional Office) 2012 Water Resources and Irrigation Development in Ethiopia (Seleshi Bekele Awulachew , Aster Denekew Yilma ,Makonnen Loulseged, Willibald Loiskandl,Mekonnen Ayana, Tena Alamirew) International Water Management Institute 2007. GPCC (Global Precipitation Climatology Center). http://gpcc.dwd.de (accessed Jan 2007). MoWR (Ministry of Water Resources).1998a. Integrated Development of Abbay River Basin Master Plan Study, Vol.III:part 2, Vol. VI: Part 1, Vol. VI: part 3, Addis Ababa: Ethiopia. MoWR (Ministry of Water Resources). 1998b. Integrated Development of Tekeze River Basin Master Plan Study,Vol. VIII: WR3, Vol. X: WR5, Vol. X: WR4, Addis Ababa: Ethiopia. MoWR (Ministry of Water Resources). 1997. Integrated Development of Baro Akobo River Basin Master Plan Study,Vol. II , Annex 1B, Annex 1H , Annex 1J, Addis Ababa: Ethiopia. MoWR (Ministry of Water Resources). 1996. Integrated Development of Omo-ghibe River Basin Master Plan Study,Vol. XI F1, F2, F3, Addis Ababa: Ethiopia. MoWR (Ministry of Water Resources). 1999. Water Resource Management Policy (WRMP), Addis Ababa: Ethiopia. MoWR (Ministry of Water Resources). 2002. Water Sector Development Program (WSDP), Addis Ababa: Ethiopia.

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