Nile

Traditional mud brick houses in Lower Egypt with the local staple crop, maize, in the foreground. Most of the villages of Lower Egypt are built on the Nile delta, where the land is fertile and crops can be irrigated from the river.

Feluccas on the River Nile, Egypt. Propelled by sails and oars, the felucca is a common means of transport on the Nile.

View of the River Nile, with the Cairo Tower and city behind. The city lies about 160 km/100 mi from the Mediterranean, just short of where the Nile delta begins. The Cairo Tower is situated on the island of Gezira Bulak, and the river at this point is 800 m/880 yd wide.

Life on the River Nile Egypt with children playing. This image is of a fresco on painted plaster, created approximately 55-79 BC.

Ferry on the Nile, at the ancient town of Aswan in southern Egypt.

River in Africa, the world's longest, 6,695 km/4,160 mi. The Blue Nile rises in Lake Tana, Ethiopia, the White Nile at Lake Victoria, and they join at Khartoum, Sudan. The huge basin of the river has an area of some 3,350,000 sq km/1,293,000 sq mi. The river enters the Mediterranean Sea through a vast delta between the Rosetta and Damietta distributaries in northern Egypt.

Its remotest headstream is the Kagera River, in Burundi. The Nile proper begins on leaving Lake Victoria above Owen Falls. From Lake Victoria it flows over rocky country, and there are many cataracts and rapids, including the Murchison Falls, until it enters Lake Albert. From here it flows across flat country and in places spreads out to form lakes. At Lake No it is joined by the Bahr al-Ghazal, and from this point to Khartoum it is called the White Nile.

At Khartoum it is joined by the Blue Nile, which rises in the Ethiopian highlands, and 320 km/200 mi below Khartoum it is joined by the Atbara. From Khartoum to Aswan there are six cataracts. The Nile is navigable to the second cataract, a distance of 1,545 km/960 mi. The delta of the Nile is 190 km/120 mi wide. From 1982 Nile water has been piped beneath the Suez Canal to irrigate Sinai. The water level behind the Aswan Dam fell from 170 m/558 ft in 1979 to 150 m/492 ft in 1988, threatening Egypt's hydroelectric power generation.

Southern tributaries The chief tributary is the Kagera, the length of which, from the source to Lake Victoria is 850 km/528 mi. The Nile leaves the lake at its northern extremity, and flows in a northwesterly direction, passing through the Ibrahim and Kioga lakes. The river leaves the central African highlands at Fauvera and turns westward, where it is known as the Somerset Nile. Between Fauvera and Lake Albert the river falls at least 300 m/984 ft, with many cataracts, such as the Murchison Falls (36 m/118 ft). After leaving this lake, and receiving as a tributary the Semlike Nile from Lake Albert, the river winds its northerly course through the plains of the eastern Sudan. Here it is navigable.

Northern tributaries The main river is split up into several channels in the Sudd region; the two main arms are the Bahr al-Jebel and the Bahr al-Seraf, which join again further north. The Bahr al-Ghazal here flows into the main stream, and deflects it for a short distance to the east, but when the Sobat joins it the course once more turns northwards. From Fashoda to Khartoum the river is known as the White Nile (Bahr al Abiad); it becomes the Nile after the junction with the Blue Nile (Bahr Al-Azraq), which joins it at Khartoum, flowing from the Ethiopian tablelands. The Atbara is the last tributary which joins the Nile at a point 320 km/200 mi below Khartoum, and is a large river in the rainy season, though greatly reduced in the dry.

The lower reaches The Libyan and the Red Sea plateaus, which approach the river in succession, are the cause of its sinuous course in Nubia. North of here there are six groups of cataracts, the largest being at Wadi Haifa. From the junction of the Atbara to the sea the Nile does not receive a single tributary, the lower basin being therefore very small in area. This region increases from less than 2 km/1.2 mi in Nubia to as much as 20 km/12 mi in Upper Egypt, and it is the extent of the annual inundation which determines the prosperity of the country.

Nile Delta The Nile Delta begins north of Cairo. It has a width of 190 km/120 mi and an area of 22,000 sq km/8,494 sq mi, with many canals and lakes. The most important branches are the Damietta and the Rosetta, each 235 km/146 mi long.

Irrigation Irrigation was begun by the Egyptian reformer Mehmet Ali; in 1842 he called in Mougel Bey, a Frenchman, who built the Cairo barrage. Water was conducted to the land by irrigation canals, but the control of the water deprived the land of silt, and its productivity decreased. Bey's barrage was used until 1883, when British engineers rebuilt it, increasing the depth of water so that it travelled down the irrigation canals with increased velocity and carried the silt with it.

Dams on the upper Nile The Aswan Dam, which was begun in 1895 and finished in 1902, was raised in height in 1912. From December to March the sluices are closed and the water held up to a maximum capacity of 5,500 million cubic m/7,193.5 million cubic yards. Before March and July the water is drawn off into the irrigation canals. Work on a new dam, the Aswan High Dam, was started in 1960 and completed in 1970. The Nile had been diverted by 1964. Above the Aswan dam is a barrage at Esna, made by placing suitable booms at an angle of 45° to the stream, and there is another barrage at Assiut. The Assiut dam gave new life to an irrigation system which was 3,000 years old. A dam at Sennar, 3 km/1.8 mi long, 275 km/171 mi south of Khartoum, was completed in 1925 to hold up the waters of the Blue Nile. The Aswan reservoir holds 5,500 million cubic m/7,193.5 million cubic yards of water, and the Gebel Aulia reservoir (completed in 1937) 2,000 million cubic m/2,615.8 million cubic yards. The Aswan High Dam stores 44.3 million cubic m/57.9 million cubic yards in Lake Nasser. New barrages have been constructed at the splitting of the Nile below Cairo to replace the existing structures which, having been built in 1861, were unable to meet the conditions following the increase in summer supplies, the reclamation of considerable waste lands, and the earlier watering of food crops.

Navigation The Mahmudick Canal, which connects the Rosetta with the Alexandria Nile, is of great commercial importance. Proir to the construction of the Aswan Dam there was continuous communication between Juba and the sea, a distance of 4,700 km/2,920 mi, but in periods of low water the cataracts impede the navigation. All the year round navigation is possible between Khartoum and Juba (1,750 km/1,087 mi) and also from the sea as far as El Mansûra (95 km/59 mi) on the Damietta, and as far as Kafr el Zayab (110 km/68 mi) on the Rosetta branch.

Water conservation The annual rise of the middle and lower Nile is due to the seasonal rains over its headwaters in Ethiopia and equatorial Africa. The White Nile constitutes a more uniform source of supply, whilst the Blue Nile and Atbara, when swollen by seasonal rain, cause the floods. Until the construction of the Aswan Dam the water level in the lower Nile rose by around 5 m/16 ft in response to flooding, but since the dam construction there has effectively been no flood, allowing perennial irrigation.

In addition to the construction of the Aswan Dam, a series of projects have been undertaken to bring the Nile under control and utilize as much of its water as possible. The principle of the projects is ‘century’ or continuous storage, enabling the maximum supply in abundant years to be conserved for years of low rainfall, and also to avoid flooding and consequent famine. Adequate water storage was, until recently, only possible in the great lakes of central Africa, lakes Victoria, Albert, Kyona and Tana, where evaporation from the lake surface and rainfall inputs are nearly equal. Reservoirs such as Lake Nasser behind the Aswan Dam are not ideal for water storage because of relatively high evaporation rates.

Some of the earliest of these projects were the construction of Owens Falls dam on Lake Victoria (built 1949-54) and the Aswan High Dam which not only control flow but also provide hydroelectric power.

Land reclamation The extension of agricultural land through reclamation has been a long-term aim of the Egyptian government, mainly to counteract losses of land to urban expansion and associated excavation of aggregate and brick-making materials. There are a number of projects for reclaiming land and allowing increased cultivation downstream of the High Aswan Dam.

A further 55 sq km/21 sq mi have been reclaimed at Radesia and Wadi Abbay, 71 sq km/21 sq mi in Kena province, 246 sq km/95 sq mi in El Minya province, and 40 sq km/15 sq mi in the Faiyum depression. The Barari swamp and lagoon area has been drained to provide 500 sq km/193 sq mi.

Ancient records Considering the great importance of the Nile to Egypt, it is not surprising that in ancient times it was deified, and it has always been regarded with the utmost reverence. Each year the Nile floods its banks and the height of the flood has been recorded annually since at least 3600 BC.

European exploration In 1771 the British explorer James Bruce followed the Blue Nile to its confluence with the White Nile, the first European to do so. In 1858 the British explorer John Hanning Speke was the first European to see Lake Victoria, which he believed was the source of the Nile. Henry Morton Stanley, a British American, explored Lake Victoria in 1875, and in 1889 visited the Ruwenzori Mountains and Lake Edward.