Geography of Nile Valley

The Nile can be divided into three zones: The tributaries, the many rivers that make up the stream of the Nile. The White and Blue Niles join near Khartoum in Sudan, and other tributaries join the White Nile further south.

The second zone is the stretch between Cairo and Khartoum. The third and last zone is the delta, where the Nile divides into several branches, of which Rosetta (Rashid) and Damietta (Dumyat) are the main ones. The Nile Delta is the widest habitable area of the Nile, and it even includes several lakes, like Manzala, Buruillus and Edku.

Modern times have added more division lines, like the two dams at Aswan. South of this the river valley opens up, allowing rich agriculture and high population density. The width of the Nile below Aswan - it’s most important stretch in terms of inhabitants and economy - is 2.8 km in average. The greatest width is at Edfu, with 7.5 km, the smallest at Silwa Gorge, near Aswan, with 350 metres.
There are also minor dams in Sudan, aiding agriculture and protecting against large floods.

About 83% of the total water of the Nile comes from Lake Tana, 1,800 metres above sea level in the Ethiopian mountains. The lake flows over every summer providing for the flood that today is tamed by the barrages of Sudan and southern Egypt. This water flows through the Blue Nile until it joins the White Nile at Khartoum, Sudan to form the Nile. The other main source is the White Nile originating in Uganda and Burundi.

It contributes with 16%, but this is a more steady flow. Without it, the river Nile would run dry in May. As there are many single contributors to the White Nile, it is a question of definition on where the Nile really starts. The longest stretch of the Nile comes with the start of Kyaka river in Burundi, close to large Lake Tanganyika. This passage goes through Lake Victoria, then Victoria Nile, Lake Albert, Albert Nile, which in Sudan is called Mountain Nile. Mountain Nile joins other rivers of Sudan to form the White Nile.