The Nile
Arabic: 'an-nīl
River flowing through Egypt and Sudan, which has its sources in Ethiopia, Uganda, Kenya, Tanzania, and Burundi. The Nile, as defined starting with the Kyaka river in Burundi, is 6,671 km long, and has a surface area of a total of 3,350,000 km² (5 times the area of France). The discharge is around 3,1 million litres per second.
The ancient name of the Nile, was Iteru. The annual flood was personified by the god Hapy, who was associated with fertility and regeneration.
GEOGRAPHY
The Nile can be divided into three zones, starting in the south: The first consists of tributaries to the two streams of the White Nile and the Blue Nile which join near Khartoum in Sudan. The second zone is the stretch between Khartoum and Cairo. The third and last zone is the Nile Delta, where the Nile divides into several branches and artificial canals. The main rivers are 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.
The width of the Nile north from Aswan in Egypt — 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.
Modern times have added more division lines, like the two dams at Aswan. 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. Lake Tana floods 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 across the Sudan border is called Mountain Nile. Mountain Nile joins other rivers of Sudan to form the White Nile.
The third notable contributor is the Atbara River, which joins the main course of the Nile 300 km north of Khartoum. Atbara River contributes with less than 1%, and runs dry at times of the year.
The Nile carries water all through the year, but the amount of water it carries, varies depending on the season. With the construction of Aswan High Dam, this is now controlled for Egypt's part. In ancient times, when agriculture depended much upon the water and the silt from the annual flood, the ideal flooding height was 7-8 metres. Less than that, and the produce was in danger. More than that, and the flood could cause major damage.
There are more dams than the one at Aswan, in Sudan the Blue Nile is dammed by Sennar Dam. The White Nile is dammed just before Khartoum. Both are important for local agriculture.
CULTURE
Around 105 million people live along the Nile, most of these in Egypt. The Nile has been the source of civilization for more than 5,000 years. The greatest of these civilizations belongs to Ancient Egypt. More recent, and less impressive, but still important was Nubia, belonging to the region of modern Sudan. This period lasted until about 0 CE.
Following that period, important cultures arose in Egypt. First was the Roman and Coptic periods, followed by a number of strong Muslim states. These include the Fatimids, the Ayyubids and finally the Mamluks. Since the 16th century, the cultures around the Nile have been weak and poor. Modern Egypt and Sudan are the poorest countries in North Africa and the Middle East, with enormous problems. Uncontrolled population growth of these two countries provide for bleak future prospect, even if the Egyptian economy has shown growth in the late 1990's.
HISTORY
6 million BCE: The earliest we know of a river through Egypt; scientists name it Eonile. This river ran through a canyon with walls that could be up to 3,000 metres high. There are indications that the Mediterranean Sea did not exist in this period. The source of Eonile is not known.
5 million: The waters of the Mediterranean Sea rises, filling up a basin reaching as far as modern Aswan. This brings an end to Eonile.
4 million: A second river starts flowing through Egypt, by modern scholars referred to as Paleonile. Its sources are believed to have been in equatorial Africa.
1.8 million: Dramatic climatic changes, causing the end of a water stream flowing north. Desertification in North Africa casues the emoty river canal to be filled with sand.
1.5 million: The third river, the Protonile, starts flowing through Egypt, creating many interwoven channels. The Protonile ran to the west of the modern Nile, through the region known today as Western Desert.
500,000: The Prenile replaces the Protonile, running further to the east, and starts carving out the river valley existing today. Its discharge was the largest ever for any of the Niles, before and since.
150,000 The Prenile starts to dry out.
30,000: The Neonile starts flowing through Egypt, basically following the same course as the modern Nile, but with a higher elevation.
8,000: The Neonile has carved itself down to the present elevation, and we can start talking about the Nile as we know it today.
1902: The Aswan Dam opens, allowing better control with the flow and flooding of the Nile through Egypt.
1960: The Aswan High Dam opens, allowing Egypt even better control with the flow all through the year, but removing the valuable silt which normally enriched the soil. A very important hydroelectric power plant is constructed here.
Hope this helps.
2006-11-07 05:05:57
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answer #1
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answered by RIDLEY 6
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The flow rate of the Albert Nile at Mongalla is almost constant throughout the year and averages 1048 cubic meters per second. After Mongalla the Nile is known as the Bahr El Jebel which enters the enormous swamps of the Sud region of the Sudan. More than half of the Nile’s water is lost in this swamp to evaporation and transpiration. The average flow rate in the Bahr El Jebel at the tails of the swamps is about 510 cubic meters per second. From here it soon meets with the Sobat River and forms the White Nile.
The average flow of the White Nile at Malakal is 924 cubic meters per second, the peak flow is approximately 1218 cubic meters per seconds in early March and minimum flow is about 609 cubic meters per seconds in late August. The fluctuation here is due the substantial variation in the flow of the Sobat which has a minimum flow of about 99 cubic meters per seconds in august and a peak flow of over 680 cubic meters per seconds in early March.
From here the White Nile flows to Khartoum where it merges with the Blue Nile to form the Nile River. Further up stream the Atbara River, the last significant Nile tributary, merges with the Nile.
The White Nile contributes approximately 31%[citation needed] of the yearly Nile discharge. However during the dry season (January to June) the White Nile contributes between 70% and 90% of the total discharge from the Nile. During this period of time the natural discharge of the Blue Nile can be as low as 113 cubic meters per seconds, although upstream dams regulate the flow of the river. During the dry period the flow of the Atbara River will typically be zero.
The Blue Nile contributes approximately 80-90% of the Nile River discharge. The flow of the Blue Nile varies considerably over its yearly cycle and is the main contribution to the large natural variation of the Nile flow. During the wet season the peak flow of the Blue Nile will often exceed 5663 cubic meters per seconds in latter August (variation by a factor of 50).
Before the placement of dams on the river the yearly discharge varied by a factor of 15 at Aswan. Peak flows of over 8212 cubic meters per seconds would occur during the later portions of August and early September and minimum flows of about 552 cubic meters per seconds would occur during later April and early May.
The Nile basin is complex and because of this the discharge at any given point along the river depends on many factors including weather, diversions, evaporation/evapotranspiration, and ground water flow.
In 1958 radioisotope tracking led to the discovery of a subterranean river, also called a crypto-river, which flows beneath the Nile. The flow of this river is very large; estimates place the annual discharge in the range of 566 cubic km. This is equivalent to an average flow rate of almost 18,000 cubic metres per second. The discharge of this crypto-river is approximately six times the annual discharge of the Nile.
2006-11-07 05:03:56
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answer #2
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answered by MЯ BAIT™ 6
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