The course of the Nile.
The Nile flows generally northward throughout its course. Its southernmost source is the Ruvironza River in Burundi. Lake Victoria ranks as the Nile's largest source. The Nile flows through the Sudd, a vast swamp in southern Sudan, where high temperatures cause about half of the water to evaporate. The Nile is called the White Nile between the Sudd and Khartoum, Sudan. At Khartoum, the Blue Nile from Ethiopia joins the White Nile. North of Khartoum, the river is called simply the Nile. The Atbara River, which is another chief source of the Nile, drains into it in Sudan, about 175 miles (282 kilometers) north of Khartoum. About 70 percent of the Nile's water comes from the Blue Nile.
The flow of water in the Blue Nile and the Atbara varies greatly. Flooding by these rivers caused the annual floods of the Nile in Egypt. North of Cairo, Egypt, the Nile divides into separate channels in the Nile Delta. The delta has some swampy land and salty lakes, as well as highly fertile soil.
