the longest river in africa and, arguably, the world.
The Nile (Bahr al-Nil) dominates the landscape of eastern and northern Africa as well as the lives and livelihood of its people. The Nile traverses 35 degrees of latitude and 4,200 miles in its flow from Burundi in the East African rift valleys through ten riparian countries to Egypt on the Mediterranean. Within this 1.25-million-square-mile drainage area, the Nile Basin encompasses unique wildlife habitats and broad biodiversity. At the same time, Nile Basin countries are home to 300 million people, a number projected to double by 2025.
The Nile Basin is environmentally sensitive. Stretching from the equator to the Mediterranean, the Nile is a principal flyway for migrating birds that nest along its many marshes, lakes, and tributaries. Its wetlands, forests, and open lands are home to a broad array of flora and fauna. Its natural beauty has attracted tourists for centuries. But increasing population and limited water supply have put stress on the people of the basin as well as on the environment. Total water and water availability per capita in the Nile Basin remain low.
Compared to other major river basins, the Nile's disparity in water availability differs sharply among sub-basins. Arid portions (perhaps one-third of the basin) yield negligible flows; in contrast, the highlands of Ethiopia, comprising 10 to 20 percent of the land area of the overall basin, and draining through the Blue Nile and Atbara, yield approximately 120 billion cubic yards, or 60 to 80 percent of the annual flow at Aswan. Flows from the White Nile originating in the region of Lake Victoria are buffered by the great Sudd swamps of southern Sudan, and thus are approximately constant through the year. Flows from the Blue Nile are concentrated in a three-month period of late summer, creating the famous annual inundation of Egypt.
Twelve miles south of Cairo, the Nile divides into the Rosetta and Damietta branches and enters the delta. For Egypt and Sudan, the river is almost the sole source of water, and their inhabitants have always been intensely concerned with the utilization of its waters. The valley of the lower Nile and delta has among the most fertile soils in the world, created by millennia of sediment deposition during the annual inundation. Since the building of the High Dam at Aswan in the 1960s, this felicitous natural process has been much curtailed. As population and industrialization grow along its banks, the quality of Nile waters has become degraded by pollution.
see also aswan high dam; egypt.
Howell, P. P., and Allan, J. A. The Nile: Resource Evaluation, Resource Management, Hydropolitics, and Legal Issues. London: SOAS/RGS, 1990.
Hurst, H. E. The Nile A General Account of the River and the Utilization of Its Waters. London: Constable, 1952.
Said, R. The River Nile: Geology, Hydrology, and Utilization. Oxford, U.K.; Pergamon, 1993.
Waterbury, John. Hydropolitics of the Nile Valley. Syracuse, NY: Syracuse University Press, 1979.
updated by gregory b. baecher
The White Nile.
Bahr al-Abyad rises in Lake No, from which it flows 625 miles (1,000 km) to Khartoum and its confluence with the Blue Nile. Flowing east, it receives significant water from its major tributary, the Sobat, which originates in Ethiopia, then swings north to contribute one-third of the total mean annual flow of the Nile. Along the reach of the White Nile the land becomes increasingly arid, and the river is dotted with clusters of water hyacinth and papyrus that become islands. It forms the reservoir behind the Jabal Awliya Dam 29 miles (47 km) south of Khartoum.
Robert O. Collins
Tributary of the Nile.
Bahr al-Jabal (Mountain River) begins at the outlet of Lake Albert (Lake Mobutu Sese Seko); from there to the river port of Nimule, it is frequently called the Albert Nile. At Nimule, the river turns north-west and plunges through a narrow gorge 100 miles (160 km) long. At Bor the Bahr al-Jabal enters the Sudd, the world's largest swamp. It then flows 231 miles (370 km) to Lake No where it joins the Bahr al-Ghazal to form the Bahr al-Abyad.
see also bahr al-abyad; bahr al-ghazal; sudd.
Robert O. Collins