Nile River Basin

The Nile River is the longest river in the world. From its major source, Lake Victoria in east central Africa, the White Nile flows generally north through Uganda and into Sudan where it meets the Blue Nile at Khartoum, which rises in the Ethiopian highlands. From the confluence of the White and Blue Nile, the river continues to flow northwards into Egypt and on to the Mediterranean Sea. From Lake Victoria to the Mediterranean Sea the length of the Nile is 5584 km (3470 mi). From its remotest headstream, the Ruvyironza River in Burundi, the river is 6671 km (4145 mi) long. The river basin has an area of more than 3,349,000 sq km (1,293,049 sq mi).

Physiography
The Nile has a number of sources. The Lake Plateau region of East Africa has several headstreams that contribute to the White Nile. In Burundi, the Kagera River is considered the furthest headstream. It rises in the highlands near the northern edge of Lake Tanganyika and then flows into Lake Victoria. The Nile River then rises from Lake Victoria (26,800 sq. miles, world's second largest freshwater lake) and flows northward near Jinja, Uganda. The Victoria Nile continues its flow into Lake Kyoga, where it passes through its swamp vegetation. Now it changes its flow and continues towards the west where it descends into the East African Rift System going over the Murchison (Kabalega) Falls. From here it flows into Lake Albert, which is deep and narrow. It now becomes the Albert Nile and continues northward through a wider section of the river.

The White Nile & The Blue Nile
The White Nile begins near Malakal, where the Sobat River (Baro in Ethiopia) enters the Nile's mainstream. It continues for about 500 miles with very little water being added from other sources along the way. This section of the Nile is wide and the water flows slowly along its course. Narrow swamps occur frequently along the edges. These conditions contribute to the massive amounts of water lost through evaporation and seepage.

The water of the Blue Nile drains from the Ethiopian Plateau, where it descends from 6,000 feet above sea level. It continues in a north-northwesterly direction through The Sudan till it reaches the White Nile at Khartoum. The White Nile has a relatively constant flow, the Blue Nile in contrast is affected by the tremendous runoff resulting from the late July to October rains on the Ethiopian Plateau. The annual floods in Egypt are a direct result of this increase in the river's water volume.

The Atbara River flows into the Nile 200 miles north of Khartoum. The Atbara is fed by the Angereb and Tekezo. These tributaries bring tremendous amounts of water from the Ethiopian highlands between July and October and contribute to the flooding downstream.

The United Nile is north of Khartoum and has two distinct parts. One part is 830 miles long and flows through a desert region. Irrigation takes place along this stretch. The second part involves Lake Nasser (2,600 sq. miles, the world's second largest man-made lake). Here the water is held back by Egypt's Aswan Dam. It is about 500 miles from the dam to Cairo. As the river runs its course through this area it averages 10 to 14 miles in width, with scarps that rise to heights of 1,500 feet above the river's level. About 200 miles from Cairo the river flows and hugs the eastern edge of the valley's floor. This has resulted in more cultivated land along the left bank of the Nile.

The Nile Delta
Another stretch of the Nile flows northward below Khartoum. A series of cataracts occur leading towards Lake Nasser. For the 800 miles that the river flows through this portion it changes from gentle sections to a series of rapids. It is the crystalline rocks that have caused five of the famous cataracts in the river making portions of it unnavigable.

Finally, the Nile delta was formed. It is composed of the silt carried by the river from the Ethiopian Plateau. This silt is 50 to 75 feet deep and has created Africa's most fertile soil. A 100 mile plain was formed and extends north and south along the Nile delta. As the land reaches the Mediterranean Sea in the north, lakes and salt marshes occur.

Burundi	Democratic Republic of Congo
Egypt	Eritrea
Ethiopia	Kenya
Rwanda	Sudan
Tanzania	Uganda

Climate
The Nile basin has two types of climates. In the northern part, the part where the Sudan and Egypt lie, has virtually no rainfall in the summer. In contrast the southern portion, which encompasses the Ethiopian Plateau, has heavy rains during the summer months. During the season between October and May both regions are relatively dry due to the presence of the northeast trade winds.

There are parts of the East African lakes region and southwestern Ethiopia that have more tropical climates. Rainfall occurs throughout these regions. However, the rainy season is considered to occur from April to October. Temperatures vary between 60 to 80 degrees F., with relative humidity averaging around 80 percent. The southernmost part of The Sudan has a similar climate, with as much as 50 inches of rain during the rainy season.

North of this tropical region there is a shorter rainy season occurring from July to August. There is less rainfall. In the central region of Sudan, the seasons start with a cool, dry winter (December to February). This changes in March to hot, dry weather with temperatures averaging 105 degrees F. Finally in July the rains come and the conditions are hot and rainy. Rainfall in this region varies from 10 to 21 inches annually. As one continues north of Khartoum the annual rainfall is 5 inches.

The remaining area in the north is characterized as having a desert climate. This area includes northern Sudan and the Egyptian desert. It is considered to be arid and extremely hot. In June the average temperature is 117 degrees F. In Egypt's desert there is a winter season with cooler temperatures and rainfall varies from one inch in the south and increases up to 8 inches as it reaches the coastal area. In these desert areas sandstorms can occur during the spring months. These sandstorms can last for three or four days and end with a "blue sun", a desert phenomenon.