The Blue Nile (; ) is a river originating at Lake Tana in Ethiopia. It travels for approximately through Ethiopia and Sudan. Along with the White Nile, it is one of the two major tributaries of the Nile and supplies about 85.6% of the water to the Nile during the rainy season.
Course
The distance of the river from its source to its confluence has been variously reported as being between and . This uncertainty might result from the fact that the river flows through a series of virtually impenetrable gorges cut in the Ethiopian Highlands to a depth of some . According to materials published by the Central Statistical Agency, the Blue Nile has a total length of , of which are inside Ethiopia.
In Ethiopia
The Blue Nile originates at Lake Tana in Ethiopia (where it is called the Abay River). The river flows generally south before entering a canyon about long, about from Lake Tana, which is a tremendous obstacle for travel and communication between north and south Ethiopia. The canyon was first referred to as the "Grand Canyon" in 1968 by a British team that accomplished the first descent of the river from Lake Tana to the end of the canyon; subsequent river rafting parties called it the "Grand Canyon of the Nile". The Blue Nile Falls (Amharic: Tis Abay, literally "great smoke"), one of Ethiopia's biggest tourist attractions, is located at the start of the canyon.
The river loops across northwest Ethiopia before being fed by numerous tributaries between Lake Tana and the Ethiopia–Sudan border. Those on its left bank, in downstream order, include the Wanqa River, the Bashilo River, the Walaqa River, the Wanchet River, the Jamma River, the Muger River, the Guder River, the Agwel River, the Nedi River, the Didessa River and the Dabus River. Those on the right side, also in downstream order, include the Handassa, Tul, Abaya, Sade, Tammi, Cha, Shita, Suha, Muga, Gulla, Temcha, Bachat, Katlan, Jiba, Chamoga, Weter and the Beles.
In Sudan
The Blue Nile then heads northwest into Sudan. It travels for approximately , flowing past Er Roseires and receiving the Dinder River on its right bank at Dinder. At Khartoum, the Blue Nile joins the White Nile and, as the Nile, flows through Egypt to the Mediterranean Sea at Alexandria.
Water flow
The flow of the Blue Nile reaches maximum volume in the rainy season from June to September, when it supplies 8086% of the water of the Nile proper. The river was a major source of the flooding of the Nile in Egypt that contributed to the fertility of the Nile Valley and the consequent rise of Ancient Egypt and Egyptian mythology. With the completion of the Aswan Dam in 1970, these floods stopped occurring in lower Egypt. During the summer monsoon season, the Blue Nile floods erode a vast amount of fertile soil from the Ethiopian Highlands and carry it downstream as silt, turning the water dark brown or almost black.
The Blue Nile is vital to the livelihood of Egypt: as the most significant tributary of the Nile, it contributes over 85% of the Nile's streamflow. Though shorter than the White Nile, 59% of the water that reaches Egypt originates from the Ethiopian highlands via the Blue Nile. The river is also an important resource for Sudan, where the Roseires Dam and Sennar Dam contribute to the 80% of the country's electricity generation from hydropower. These dams also help irrigate the Gezira Scheme, which is most famous for its high-quality cotton, as well as wheat and animal feed crop production in the area.
In November 2012, Ethiopia began construction of the Grand Ethiopian Renaissance Dam, a 6000-megawatt hydroelectric dam on the river. The dam is expected to be a boost for the Ethiopian economy. Sudan and Egypt, however, voiced their concerns over a potential reduction in water available. Electricity generation began in February 2022.
History
Early European exploration
The first European known to have seen the Blue Nile in Ethiopia and the river's source was Pedro Páez, a Spanish Jesuit who reached the river's source on 21 April 1618. However, the Portuguese João Bermudes, the self-described "Patriarch of Ethiopia," provided the first description of the Tis Abay River Falls in his memoirs published in 1565, and any number of Europeans who lived in Ethiopia in the late 15th century such as Pêro da Covilhã could have seen the river long before Páez, but not reached its source. The source of the Nile proper was also reached in 1629 by the Portuguese Jesuit missionary Jerónimo Lobo and in 1770 by the Scottish explorer James Bruce.