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Tana
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Tis Issat Falls on the Blue Nile River below Lake Tana, November 2003
Photo credit: L. Borre |
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General Information
| Description |
Lake Tana is the largest lake in Ethiopia and is the source of the Blue Nile, which flows to Khartoum, Sudan and beyond. There are 37 islands in the lake, upon which some 20 monasteries from the 16th and 17th century exist.
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| Country |
Ethiopia
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| Latitude |
12° 10' 0"
(12.1667) |
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| Longitude |
37° 20'
0" (37.3333) |
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| State |
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| River Basin |
Nile
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Maps
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Tana global index map (LakeNet Explorer)
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Tana locator map |
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Lakes of Ethiopia |
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Africa Lake Biodiversity Conservation Priorities 2003 |
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USAID-supported Lake Basin Management and Biodiversity Conservation Technical Assistance 2003-2004 (LakeNet Explorer)
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Physical Characteristics
| Description |
Although it is relatively small in comparison with the three “great lakes” of East Africa--Lake Victoria is approximately 20 times larger--Lake Tana is very important to Ethiopia as a permanent source of both water and hydroelectricity in the drought-prone region. The lake is situated in the northern highlands at an altitude of approximately 1800 meters. Four perennial rivers and numerous seasonal streams feed the lake, depends heavily on the local climate. Rainfall averages 1315 mm/year, but evaporation is higher, about 1800 mm/year. With a mean depth of 8 only meters, the alternating dry and rainy seasons result in an average difference of 1.5 to 2 meters between the lowest (May-June) and highest (October-November) lake levels.
Lake Tana was formed by a volcanic blockage that reversed the previously north-flowing Blue Nile and created one of Africa’s greatest waterfalls, known as Tis Abay or Tis Isat. The falls isolated the lake, in which 18 species of barbus fish evolved, the only extended cyprinid species flock in Africa and the only intact flock in the world. The only other known flock, in Lake Lanao, in the Philippines, has been decimated by introduced species. |
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| Volume |
28.00 km3 |
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| Surface Area |
3,600.00 km2 |
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| Depth |
Mean depth: 9.0 m
Maximum depth: 14.0 m
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| Residence Time |
1.5 years |
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| Origin |
Volcanic
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| Trophic State |
Mesotrophic |
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| Type |
Fresh
Permanent
Natural
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| Catchment |
Catchment size: 16,500.00
km2
Catchment/surface area ratio: 5:1 |
Socio-Political
| Economic Value |
The Lake Tana Basin significantly contributes to the livelihoods of tens of millions of people in the lower Nile River basin. The fish resource potential of the Lake Tana itself is over 10,000 metric tons per year. The lake is also a natural reservoir for the eighty-megawatt runoff power station at Tis Abay.
The largest city on the lake shore, Bahir Dar, has a population of over 200,000, and at least 15,000 people are said to live on the islands in the lake. Bahir Dar is the capital of the Amhara Province and is home to Bahir Dar University (BDU), which was established in the 1990s by the Ministry of Education, by amalgamating agricultural and teacher training institutions. |
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| Major Cities |
Bahir Dar |
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| Population |
806,545 (1980) |
Watershed Management
| Description |
A Lake Tana Resource Management Research Center has been established at Bahir Dar University which plans to investigate water quality, land use, and biodiversity in the lake basin. They are currently planning a National Lake Symposium (2003). |
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| Issues |
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| Other Issues |
Erosion
Floods
Hydropower
Biodiversity Conservation
Lake Levels (water quantity)
Fisheries
Nutrient pollution
Point source pollution
Polluted runoff
Cultural Heritage
Sand mining
Watershed habitat alteration
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| Specific Contaminants |
Pesticides
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| Monitoring |
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Biodiversity Conservation
| Description |
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| Designations |
LakeNet Biodiversity Priority
WWF Global 200
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| Species of Concern |
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Organizations
LakeNet Programs
Documents
Resources
News
Additional Data Sources
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Birkett, C., and I. Mason. 1995. A new global lakes database for remote sensing programme studying climatically sensitive large lakes. Journal of Great Lakes Research, 21 (3) 307-318. |
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Duker, L. and L. Borre. 2001. Biodiversity conservation of the world's lakes: a preliminary framework for identifying priorities. LakeNet Report Series Number 2. Annapolis, Maryland USA. |
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International Lake Environment Committee, the United Nations Environment Program and Environment Agency, Government of Japan. 1997. World Lakes Database. |
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