Spanning approximately 4,258 miles, the Nile is the world's longest river and has two major tributaries, the White Nile which begins in Burundi, and the Blue Nile which starts in Ethiopia. The two rivers merge to form the Nile in Khartoum, Sudan. It flows northwards, passing through 11 countries: Rwanda, Burundi, Tanzania, Kenya, Uganda, The DRC, South Sudan, Sudan, Ethiopia, Eritrea, and Egypt. The river pours into the Mediterranean Sea at the Nile Delta located near Cairo, Egypt, which is approximately 99.4 miles long and 149 miles wide, making it one of the world’s biggest deltas.
The White Nile
The White Nile refers to the section of the Nile between Khartoum, Sudan and Malakal, South Sudan. The river gets its name from its light grey color that comes from the light colored clay sediments in the water. It is formed at the confluence of the Sobat River and the Mountain Nile (Bahr al-Jabal) and flows 500 miles north to join the Blue Nile, thereby forming the Nile. The White Nile has a total length of 1295 miles, which includes its main tributary, the Mountain Nile. During the floods that generally occur in June-September period, the total amount of water contributed by the White Nile to the main Nile is less than 30% because the flooding water of Blue Nile holds back the water from the White Nile, converting it into a lake. During the low water season, which occurs between April and May, the flow of White Nile is uninterrupted and contributes about 80% of the Nile's total volume.
The Blue Nile
The Blue Nile is locally known as the Abbay and is a major tributary of the Nile. The Blue Nile is about 900 miles long and flows from Lake Tana, Ethiopia to Khartoum, Sudan. After leaving Lake Tana, the Blue Nile flows 19 miles and enters a canyon that is 250 miles long. The canyon separates the northern and southern halves of Ethiopia and is a significant obstacle for transport and communication. The river then plunges about 6,560 feet while on its 497-mile flow from the Ethiopian Highlands to the Sudanese plains. The river contributes approximately 80% of River Nile’s proper waters during the rainy season. The Blue Nile’s principal tributaries are the Rahad and Dinder rivers, which source their waters from the Ethiopian Highlands. The Blue Nile is known for the Tis-Isat Falls (which locally translates to ‘Smoke of Fire’) which is 148 feet high. The Blue Nile is also known to be a source of the Nile's fertile soils.
Economic Significance of the Nile's Tributaries
The Blue and White Nile Rivers have enormous amounts of untapped potential. For example, the Blue Nile contributes immensely to Sudan’s and Ethiopia’s economies, because it is the primary source of hydroelectric power and contributes 80% of Sudan’s electric power produced at the Sennar and Roseires dams. Dams constructed along the Blue Nile in Sudan assist in irrigation of the Gezira Plain, which produces crops such as wheat and cotton. The Blue Nile is tapped to form the Grand Ethiopian Renaissance Dam, which is expected to produce 6000 megawatts of electricity. Upon completion of the project, Ethiopia expects to export the surplus electricity to neighboring countries including Sudan, Kenya, and Djibouti. The White Nile supports agriculture, which is Sudan’s most important economic activity. From early historical times, the White Nile's banks have been cultivated. Numerous irrigation schemes have been established for the mass production of food crops.