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Blue Nile,Arab. Bahr el Azraq, river, c.1,000 mi (1,600 km) long, the chief headstream of the NileNile,
longest river in the world, c.4,160 mi (6,695 km) long from its remotest headstream, the Luvironza River in Burundi, central Africa, to its delta on the Mediterranean Sea, NE Egypt. The Nile flows northward and drains c.
..... Click the link for more information. , rising in Lake Tana, NW Ethiopia, at an altitude of c.6,000 ft (1,800 m). It flows generally S from the Lake Tana region, then W across Ethiopia, and finally NW into Sudan. At Khartoum the Blue Nile merges with the White NileWhite Nile,
river, one of the chief tributaries of the Nile, E Africa. The name is sometimes used for the 600 mi (970 km) long section of the river known as the Bahr el Abiad that extends upstream from Khartoum to the junction of the Bahr el Jebel and the Bahr el Ghazal at Lake
..... Click the link for more information. to form the Nile proper. The flow of the Blue Nile reaches maximum volume in the rainy season (from June to September), when it supplies about two thirds of the water of the Nile proper. The Blue Nile used to cause the annual Nile flood before the completion in 1970 of the Aswan High Dam (see under AswanAswan
, city (1986 pop. 190,579), capital of Aswan governorate, S Egypt, on the Nile River at the First Cataract. It is one of the driest cities in the world.
..... Click the link for more information. ) in Egypt. In Ethiopia the Blue Nile, also known there as the Abbai, flows in a deep gorge and receives many tributaries. There are dams on the Blue Nile at Roseires and Sennar in Sudan; the latter is used to irrigate the Al GeziraGezira, Al
, or Al Jazirah
, region, SE Sudan, occupying the tract between the White and Blue Niles south of their convergence at Khartoum. The Arabic word Gezira means "island" or "peninsula." Wad Madani is the region's chief town.
..... Click the link for more information. region.
(Bahr el Azraq; Arabic bahr—river, and azraq—blue), a river in Ethiopia and the Sudan; a right tributary of the Nile and the one providing it with the most water. Length, 1,600 km. The Blue Nile originates as the Little Abbai on the southwestern slopes of the Choke Mountains south of Lake Tana. The Little Abbai flows into Lake Tana and flows out of it under the name of Abbai. The Tis-Asat waterfall (45 m high) is located 20 km farther downstream.
The Blue Nile flows at first between low banks, but then it flows 500 km through a canyon 900–1,200 m deep and 100–200 m wide. When it flows into the territory of the Sudan, it is given the name “Blue Nile,” and it changes strikingly in character. Below Roseires it descends very gradually and meanders a great deal. Its main tributaries are the Rahad and the Dinder. At the city of Khartoum it merges with the White Nile forming the Nile.
The Blue Nile is fed by rainwater. Its discharge varies sharply. (At Khartoum, it ranges from 127 cu m per sec in February to 5,822 cu m per sec in August.) On the average, it carries 52 cu km of water per year (1,650 cu m per sec). At the city of Sennar there is a dam and a 19-megawatt (19,000 kilowatts) hydroelectric power plant. In 1971 a reservoir was under construction 8 km above the city of Roseires. The Blue Nile is navigable to a point 580 km above its mouth. During the flood season ships can travel 250 km up the Rahad and 600 km up the Dinder.