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Nile

2007 Schools Wikipedia Selection. Related subjects: African Geography

                                  Nile
   The River Nile in Egypt

                           The River Nile in Egypt

   Origin           Africa
   Mouth            Mediterranean Sea
   Basin countries  Sudan, Burundi, Rwanda, DR Congo, Tanzania, Kenya,
                    Uganda, Ethiopia, Egypt
   Length           6,695 km (4,160 mi)
   Source elevation 1,134 m (3,721 ft)
   Avg. discharge   2,830 m³/s (99,956 ft³/s)
   Basin area       3,400,000 km² (1,312,740 mi²)

   The Nile (Arabic: النيل‎, translit: an-nīl, Ancient Egyptian iteru) is
   a major north-flowing river in Africa, generally regarded as the
   longest river on Earth, though some sources claim the Amazon in South
   America is longer. The Nile has two major tributaries, the White Nile
   and Blue Nile, the latter being the source of most of the Nile's water
   and fertile soil, but the former being the longer of the two. The White
   Nile rises in the Great Lakes region of central Africa, with the most
   distant source in southern Rwanda 2°16′55.92″S, 29°19′52.32″E, and
   flows north from there through Tanzania, Lake Victoria, Uganda and
   southern Sudan, while the Blue Nile starts at Lake Tana in Ethiopia,
   flowing into Sudan from the southeast. The two rivers meet near the
   Sudanese capital Khartoum.

   The northern section of the river flows almost entirely through desert,
   from Sudan into Egypt, a country whose civilization has depended on the
   river since ancient times. Most of the population of Egypt and all of
   its cities, with the exception of those near the coast, lie along those
   parts of the Nile valley north of Aswan; and nearly all the cultural
   and historical sites of Ancient Egypt are found along the banks of the
   river.

   The Nile ends in a large delta that empties into the Mediterranean Sea.

Etymology of the word Nile

   Enlarge

   The word "Nile" (Arab. 'nīl) comes from the Greek word Neilos (Νειλος),
   meaning river valley. The ancient Egyptians called the Nile iteru,
   meaning "big river", represented by the hieroglyphs shown on the right
   (literally itrw).

Tributaries

   East Africa, showing the course of the River Nile, with the "Blue" and
   "White" Niles marked in those colours
   Enlarge
   East Africa, showing the course of the River Nile, with the "Blue" and
   "White" Niles marked in those colours

   The drainage basin of the Nile covers 3,254,555 km², about 10% of the
   area of Africa .

   There are two great Tributaries of the Nile: the White Nile, beginning
   in equatorial East Africa, and the Blue Nile, beginning in Ethiopia.
   Both branches are on the western flanks of the East African Rift, the
   southern part of the Great Rift Valley. Another less important one is
   Atbara which flows only while there is rain in Ethiopia and dries very
   fast.

White Nile

   The source of the Nile is sometimes considered to be Lake Victoria, but
   the lake itself has feeder rivers of considerable size. The most
   distant stream emerges from Nyungwe Forest in Rwanda, via the Rukarara,
   Mwogo, Nyabarongo and Kagera rivers, before flowing into Lake Victoria
   in Tanzania near the town of Bukoba.

   The Nile leaves Lake Victoria at Ripon Falls, near Jinga, Uganda, as
   the Victoria Nile. It flows for approximately 500 km (300 miles)
   farther, through Lake Kyoga, until it reaches Lake Albert. After
   leaving Lake Albert, the river is known as the Albert Nile. It then
   flows into Sudan, where it becomes known as the Bahr al Jabal ("River
   of the Mountain"). At the confluence of the Bahr al Jabal with the Bahr
   al Ghazal, itself 720 km (445 miles) long, the river becomes known as
   the Bahr al Abyad, or the White Nile, from the white-ish clay suspended
   in its waters. From there, the river flows to Khartoum.

Blue Nile

   The Blue Nile ( Ge'ez ጥቁር ዓባይ Ṭiqūr ʿĀbbāy (Black Abay) to Ethiopians;
   Bahr al Azraq to Sudanese) springs from Lake Tana in the Ethiopian
   Highlands. The Blue Nile flows about 1,400 km (850 miles) to Khartoum,
   where the Blue Nile and White Nile join to form the "Nile proper". 90%
   of the water and 96% of the transported sediment carried by the Nile
   originates in Ethiopia, but this runoff happens only in summer, when
   the great rains fall on the Ethiopian Plateau; the rest of the year,
   the great rivers draining Ethiopia into the Nile (Sobat, Blue Nile, and
   Atbarah) flow weakly.
   Composite satellite image of the White Nile (see also the Nile delta)
   Enlarge
   Composite satellite image of the White Nile (see also the Nile delta)

Hydrology

   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% 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.

Distributaries or branches

   After the Blue and White Niles merge, the only remaining major
   tributary is the Atbara River, which originates in Ethiopia north of
   Lake Tana, and is approximately 800 km (500 miles) long. It joins the
   Nile approximately 300 km (200 miles) past Khartoum. The Nile is also
   unusual in that its last tributary (the Atbara) joins it approximately
   halfway to the sea. From that point north, the Nile diminishes because
   of evaporation.

   The Nile in Sudan is distinctive for two reasons: 1) it flows over 6
   groups of cataracts, from the first at Aswan to the sixth at Sabaloka
   (just north of Khartoum); and 2) it reverses direction for much of its
   course, flowing back toward the southwest before returning to flow
   north again to the sea. This is called the `"Great Bend of the Nile."'

   The Nile splits into two branches (or distributaries), the Rosetta
   Branch to the west and the Damietta to the east, North of Cairo,
   forming the Nile Delta

History

   The confluence of the Kagera and Ruvubu rivers near Rusumo Falls, part
   of the Nile's upper reaches.
   Enlarge
   The confluence of the Kagera and Ruvubu rivers near Rusumo Falls, part
   of the Nile's upper reaches.

   The Nile (iteru in Ancient Egyptian) was the lifeline of the ancient
   Egyptian civilization, with most of the population and all of the
   cities of Egypt resting along those parts of the Nile valley lying
   north of Aswan. The Nile has been the lifeline for Egyptian culture
   since the Stone Age. Climate change, or perhaps overgrazing, desiccated
   the pastoral lands of Egypt to form the Sahara desert, possibly as long
   ago as 8000 BC, and the inhabitants then presumably migrated to the
   river, where they developed a settled agricultural economy and a more
   centralized society.

Role in the founding of Egyptian civilization

   Sustenance played a crucial role in the founding of Egyptian
   civilization. The Nile was an unending source of sustenance. The Nile
   made the land surrounding it extremely fertile when it flooded or was
   inundated annually. The Egyptians were able to cultivate wheat and
   crops around the Nile, providing food for the general population. Also,
   the Nile’s water attracted game such as water buffalo; and after the
   Persians introduced them in the 7th century BC, camels. These animals
   could be killed for meat, or could be captured, tamed and used for
   ploughing — or in the camels' case, travelling. Water was vital to both
   people and livestock. The Nile was also a convenient and efficient way
   of transportation for people and goods.

   Egypt’s stability was one of the best structured in history. In fact,
   it might easily have surpassed many modern societies. This stability
   was an immediate result of the Nile’s fertility. The Nile also provided
   flax for trade. Wheat was also traded, a crucial crop in the Middle
   East where famine was very common. This trading system secured the
   diplomatic relationship Egypt had with other countries, and often
   contributed to Egypt's economic stability. Also, the Nile provided the
   resources such as food or money, to quickly and efficiently raise an
   army. Whether the army was to take on a defensive or offensive role is
   unknown.

   The Nile played a major role in politics and social life. The Pharaoh
   would supposedly flood the Nile, and in return for the life-giving
   water and crops, the peasants would cultivate the fertile soil and send
   a portion of the resources they had reaped to the Pharaoh. He or she
   would in turn use it for the wellbeing of Egyptian society.

   The Nile was a source of spiritual dimension. The Nile was so
   significant to the lifestyle of the Egyptians, that they created a god
   dedicated to the welfare of the Nile’s annual inundation. The god’s
   name was Hapi, and both he and the Pharaoh were thought to control the
   flooding of the Nile River. Also, the Nile was considered as a causeway
   from life to death and afterlife. The east was thought of as a place of
   birth and growth, and the west was considered the place of death, as
   the god Ra, the sun, underwent birth, death, and resurrection each time
   he crossed the sky. Thus, all tombs were located west of the Nile,
   because the Egyptians believed that in order to enter the afterlife,
   they must be buried on the side that symbolized death.

   The Greek historian, Herodotus, wrote that ‘Egypt was the gift of the
   Nile’, and in a sense that is correct. Without the waters of the Nile
   River for irrigation, Egyptian civilization would probably have been
   short-lived. The Nile provided the elements that make a vigorous
   civilization, and contributed much to its lasting three thousand years.

   That far-reaching trade has been carried on along the Nile since
   ancient times can be seen from the Ishango bone, possibly the earliest
   known indication of Ancient Egyptian multiplication, which was
   discovered along the headwaters of the Nile River (near Lake Edward, in
   northeastern Congo) and was carbon-dated to 20,000 BC.

The river today

   View of the Nile from a cruiseboat, between Luxor and Aswan in Egypt
   Enlarge
   View of the Nile from a cruiseboat, between Luxor and Aswan in Egypt
   The Eternal Nile
   Enlarge
   The Eternal Nile

   The Nile still supports much of the population living along its banks,
   with the Egyptians living in otherwise inhospitable regions of the
   Sahara. The river flooded every summer, depositing fertile soil on the
   fields. The flow of the river is disturbed at several points by
   cataracts, which are sections of faster-flowing water with many small
   islands, shallow water, and rocks, forming an obstacle to navigation by
   boats. The sudd in the Sudan also forms a formidable obstacle for
   navigation and flow of water, to the extent that Egypt had once
   attempted to dig a canal (the Jongeli Canal) to improve the flow of
   this stagnant mass of water (also known as Lake No).

   The Nile was, and still is, used to transport goods to different places
   along its long path; especially since winter winds in this area blow up
   river, the ships could travel up with no work by using the sail, and
   down using the flow of the river. While most Egyptians still live in
   the Nile valley, the construction of the Aswan High Dam (finished in
   1970) to provide hydroelectricity ended the summer floods and their
   renewal of the fertile soil.

   Cities on the Nile include Khartoum, Aswan, Luxor ( Thebes), and the
   Giza–Cairo conurbation. The first cataract, the closest to the mouth of
   the river, is at Aswan to the north of the Aswan Dams. The Nile north
   of Aswan is a regular tourist route, with cruise ships and traditional
   wooden sailing boats known as feluccas. In addition, many "floating
   hotel" cruise boats ply the route between Luxor and Aswan, stopping in
   at Edfu and Kom Ombo along the way. It used to be possible to sail on
   these boats all the way from Cairo to Aswan, but security concerns have
   shut down the northernmost portion for many years.

Flooding of the Nile

   The annual cycles of the Nile were very important to the lives of
   ancient Egyptians. Egypt’s stability was one of the best structured in
   history. In fact, it might easily have surpassed many modern societies.
   This stability was an immediate result of the Nile’s fertility. The
   Nile also provided flax for trade. Wheat was also traded, a crucial
   crop in the Middle East where famine was very common. This trading
   system secured the diplomatic relationship Egypt had with other
   countries, and often contributed to Egypt's economic stability. Also,
   the Nile provided the resources such as food or money, to quickly and
   efficiently raise an army, whether the army was to take on a defensive
   or offensive role.

   The Nile played a major role in politics and social life. The Pharaoh
   would supposedly flood the Nile, and in return for the life-giving
   water and crops, the peasants would cultivate the fertile soil and send
   a portion of the resources they had reaped to the Pharaoh. He or she
   would in turn use it for the wellbeing of Egyptian society.

   The Nile was a source of spiritual dimension. The Nile was so
   significant to the icial means, the water of the Nile to the meadows on
   its banks—if this be the inundation that is meant, it is true; any
   other is false; it is not an inundating river."

   More recently, drought during the 1980s led to widespread starvation in
   Ethiopia and Sudan but Egypt was protected from drought by water
   impounded in Lake Nasser. Beginning in the 1980s techniques of analysis
   using hydrology transport models have been used in the Nile to analyze
   water quality.

The Eonile

   The present Nile is at least the fifth river that has flowed north from
   the Ethiopian Highlands. Satellite imagery was used to identify dry
   watercourses in the desert to the west of the Nile. An Eonile canyon,
   now filled by surface drift, represents an ancestral Nile called the
   Eonile that flowed during the later Miocene (23-5.3 million years
   before the present). The Eonile transported clastic sediments to the
   Mediterranean, where several gas fields have been discovered within
   these sediments. South of Cairo, the sand-filled canyon can reach a
   depth of up to 1400 meters.

   During the late-Miocene Messinian Salinity Crisis, when the
   Mediterranean Sea was a closed basin and sealevel in the sea dropped
   approximately 1500 m, the Nile cut its course down to the new base
   level until it was several hundred feet below world ocean level at
   Aswan. This huge canyon is now full of later sediment.

   Formerly, Lake Tanganyika drained northwards into the Nile, until the
   Virunga Volcanoes blocked its course in Rwanda. That would have made
   the Nile much longer, with its longest headwaters in northern Zambia.

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