Misplaced Pages

#809190

86-504: The river's drainage basin is 2,160 square kilometres (830 sq mi). 58°17′00″N 121°45′00″W  /  58.28333°N 121.75000°W  / 58.28333; -121.75000 This article related to a river in the Interior of British Columbia , Canada is a stub . You can help Misplaced Pages by expanding it . Drainage basin A drainage basin is an area of land in which all flowing surface water converges to

172-484: A sink , which may be a permanent lake, a dry lake , or a point where surface water is lost underground . Drainage basins are similar but not identical to hydrologic units , which are drainage areas delineated so as to nest into a multi-level hierarchical drainage system . Hydrologic units are defined to allow multiple inlets, outlets, or sinks. In a strict sense, all drainage basins are hydrologic units but not all hydrologic units are drainage basins. About 48.71% of

258-414: A watershed , though in other English-speaking places, "watershed" is used only in its original sense, that of the drainage divide line. A drainage basin's boundaries are determined by watershed delineation , a common task in environmental engineering and science. In a closed drainage basin, or endorheic basin , rather than flowing to the ocean, water converges toward the interior of the basin, known as

344-433: A Turkish officer, Selim Bimbashi, were made between 1839 and 1842, and two got to the point about 30 kilometres (20 miles) beyond the present port of Juba , where the country rises and rapids make navigation very difficult. Lake Victoria was first sighted by Europeans in 1858 when British explorer John Hanning Speke reached its southern shore while traveling with Richard Francis Burton to explore central Africa and locate

430-736: A distance of 20 days' journey till it reaches the nearest Ethiopians." Modern exploration of the Nile basin began with the conquest of the northern and central Sudan by the Ottoman viceroy of Egypt, Muhammad Ali , and his sons from 1821 onward. As a result of this, the Blue Nile was known as far as its exit from the Ethiopian foothills and the White Nile as far as the mouth of the Sobat River. Three expeditions under

516-449: A drainage basin, and there are different ways to interpret that data. In the unlikely event that the gauges are many and evenly distributed over an area of uniform precipitation, using the arithmetic mean method will give good results. In the Thiessen polygon method, the drainage basin is divided into polygons with the rain gauge in the middle of each polygon assumed to be representative for

602-540: A drainage boundary is referred to as watershed delineation . Finding the area and extent of a drainage basin is an important step in many areas of science and engineering. Most of the water that discharges from the basin outlet originated as precipitation falling on the basin. A portion of the water that enters the groundwater system beneath the drainage basin may flow towards the outlet of another drainage basin because groundwater flow directions do not always match those of their overlying drainage network. Measurement of

688-462: A factor of 15 at Aswan. Peak flows of over 8,212 m /s (290,000 cu ft/s) occurred during late August and early September, and minimum flows of about 552 m /s (19,500 cu ft/s) occurred during late April and early May. The Bahr al Ghazal and the Sobat River are the two most important tributaries of the White Nile in terms of discharge. The Bahr al Ghazal's drainage basin

774-673: A limited sense to describe the section between Lake No and Khartoum. At Khartoum, the river is joined by the Blue Nile . The White Nile starts in equatorial East Africa, and the Blue Nile begins in Ethiopia. Both branches are on the western flanks of the East African Rift . The source of the Blue Nile is Lake Tana in the Gish Abay region in the Ethiopian Highlands . The source of

860-587: A peak flow of over 680 m /s (24,000 cu ft/s) in October. During the dry season (January to June) the White Nile contributes between 70% and 90% of the total discharge from the Nile. Below Renk , the White Nile enters Sudan, it flows north to Khartoum and meets the Blue Nile. The course of the Nile in Sudan is distinctive. It flows over six groups of cataracts , from the sixth at Sabaloka just north of Khartoum northward to Abu Hamad . The tectonic uplift of

946-513: A place described as the source of the Rukarara tributary, and by hacking a path up steep jungle-choked mountain slopes in the Nyungwe Forest found (in the dry season ) an appreciable incoming surface flow for many kilometres upstream, and found a new source, giving the Nile a length of 6,758 km (4,199 mi). The White Nile leaves Lake Victoria at Ripon Falls near Jinja, Uganda , as

SECTION 10

#1732873104810

1032-564: A single point, such as a river mouth , or flows into another body of water , such as a lake or ocean . A basin is separated from adjacent basins by a perimeter, the drainage divide , made up of a succession of elevated features, such as ridges and hills . A basin may consist of smaller basins that merge at river confluences , forming a hierarchical pattern . Other terms for a drainage basin are catchment area , catchment basin , drainage area , river basin , water basin , and impluvium . In North America, they are commonly called

1118-461: Is an archaeological site located in alluvial deposits formed by an ancient channel of the Nile in the Affad region of southern Dongola Reach , Sudan. There are two theories about the age of the integrated Nile. One is that the integrated drainage of the Nile is of young age and that the Nile basin was formerly broken into series of separate basins, only the most northerly of which fed a river following

1204-639: Is called an-Nīl . In Biblical Hebrew , it is הַיְאוֹר ‎, Ha-Ye'or or הַשִׁיחוֹר ‎, Ha-Shiḥor . The English name Nile and the Arabic names en-Nîl and an-Nîl both derive from the Latin Nilus and the Ancient Greek Νεῖλος . Beyond that, however, the etymology is disputed. Homer called the river Αἴγυπτος , Aiguptos , but in subsequent periods, Greek authors referred to its lower course as Neilos ; this term became generalized for

1290-674: Is known as the Bahr al Jabal ("Mountain River" ). Just south of the town is the confluence with the Achwa River . The Bahr al Ghazal , 716 kilometers (445 mi) long, joins the Bahr al Jabal at a small lagoon called Lake No , after which the Nile becomes known as the Bahr al Abyad , or the White Nile, from the whitish clay suspended in its waters. When the Nile floods it leaves a rich silty deposit which fertilizes

1376-480: Is referred to as " watershed management ". In Brazil , the National Policy of Water Resources, regulated by Act n° 9.433 of 1997, establishes the drainage basin as the territorial division of Brazilian water management. When a river basin crosses at least one political border, either a border within a nation or an international boundary, it is identified as a transboundary river . Management of such basins becomes

1462-600: Is the Dead Sea . Drainage basins have been historically important for determining territorial boundaries, particularly in regions where trade by water has been important. For example, the English crown gave the Hudson's Bay Company a monopoly on the fur trade in the entire Hudson Bay basin, an area called Rupert's Land . Bioregional political organization today includes agreements of states (e.g., international treaties and, within

1548-568: Is the largest of any of the Nile's sub-basins, measuring 520,000 square kilometers (200,000 sq mi) in size, but it contributes a relatively small amount of water, about 2 m /s (71 cu ft/s) annually, because tremendous volumes of water are lost in the Sudd wetlands. The Sobat River, which joins the Nile a short distance below Lake No, drains about half as much land, 225,000 km (86,900 sq mi), but contributes 412 cubic meters per second (14,500 cu ft/s) annually to

1634-682: The African Great Lakes , the interiors of Australia and the Arabian Peninsula , and parts in Mexico and the Andes . Some of these, such as the Great Basin, are not single drainage basins but collections of separate, adjacent closed basins. In endorheic bodies of water where evaporation is the primary means of water loss, the water is typically more saline than the oceans. An extreme example of this

1720-792: The Continental Divide , northern Alaska and parts of North Dakota , South Dakota , Minnesota , and Montana in the United States, the north shore of the Scandinavian peninsula in Europe, central and northern Russia, and parts of Kazakhstan and Mongolia in Asia , which totals to about 17% of the world's land. Just over 13% of the land in the world drains to the Pacific Ocean . Its basin includes much of China, eastern and southeastern Russia, Japan,

1806-681: The Korean Peninsula , most of Indochina, Indonesia and Malaysia, the Philippines, all of the Pacific Islands , the northeast coast of Australia , and Canada and the United States west of the Continental Divide (including most of Alaska), as well as western Central America and South America west of the Andes. The Indian Ocean 's drainage basin also comprises about 13% of Earth's land. It drains

SECTION 20

#1732873104810

1892-633: The Murchison Falls until it reaches the northern shores of Lake Albert where it forms a significant river delta. Lake Albert is on the border of the Democratic Republic of the Congo, but the Nile is not a border river at this point. After leaving Lake Albert, the river continues north through Uganda and is known as the Albert Nile . The White Nile flows into South Sudan just south of Nimule , where it

1978-647: The Nubian Swell diverts the river south-west for over 300 km, following the structure of the Central African Shear Zone embracing the Bayuda Desert . At Al Dabbah it resumes its northward course towards the first cataract at Aswan forming the S-shaped Great Bend of the Nile mentioned by Eratosthenes . In the north of Sudan, the river enters Lake Nasser (known in Sudan as Lake Nubia),

2064-634: The Paleogene and Neogene Periods (66 million to 2.588 million years ago) a series of separate closed continental basins each occupied one of the major parts of the Sudanese Rift System: Mellut rift , White Nile rift , Blue Nile rift , Atbara rift and Sag El Naam rift . The Mellut Basin is nearly 12 kilometers (7.5 mi) deep at its central part. This rift is possibly still active, with reported tectonic activity in its northern and southern boundaries. The Sudd swamp which forms

2150-503: The Rhône and Po , one of the three Mediterranean rivers with the largest water discharge . The standard English names "White Nile" and "Blue Nile" refer to the river's source, derived from Arabic names formerly applied to only the Sudanese stretches that meet at Khartoum . In the ancient Egyptian language , the Nile is called Ḥꜥpy (Hapy) or Jtrw (Iteru), meaning "river". In Coptic ,

2236-467: The Sudd region. More than half of the Nile's water is lost in this swamp to evaporation and transpiration . The average flow rate of the White Nile at the tails of the swamps is about 510 m /s (18,000 cu ft/s). From here it meets with the Sobat River at Malakal . On an annual basis, the White Nile upstream of Malakal contributes about 15% of the total outflow of the Nile. The average flow of

2322-621: The groundwater . A drainage basin is an area of land where all flowing surface water converges to a single point, such as a river mouth, or flows into another body of water, such as a lake or ocean. Nile River The Nile (also known as the River Nile or Nile River ) is a major north-flowing river in northeastern Africa . It flows into the Mediterranean Sea . The Nile is the longest river in Africa. It has historically been considered

2408-623: The longest river in the world , though this has been contested by research suggesting that the Amazon River is slightly longer. Of the world's major rivers, the Nile is one of the smallest, as measured by annual flow in cubic metres of water. About 6,650 km (4,130 mi) long, its drainage basin covers eleven countries: the Democratic Republic of the Congo , Tanzania , Burundi , Rwanda , Uganda , Kenya , Ethiopia , Eritrea , South Sudan , Sudan , and Egypt . In particular,

2494-428: The "Victoria Nile." It flows north for some 130 kilometers (81 mi) to Lake Kyoga . The last part of the approximately 200 kilometers (120 mi) river section starts from the western shores of the lake and flows at first to the west until just south of Masindi Port , where the river turns north, then makes a great half circle to the east and north to Karuma Falls . For the remaining part, it flows westerly through

2580-414: The Ethiopian rainy season when rainfall is especially high in the Ethiopian Highlands ; the rest of the year, the great rivers draining Ethiopia into the Nile have a weaker flow. In harsh and arid seasons and droughts, the Blue Nile dries out completely. 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

2666-610: The Ethiopian Highlands, satellite imagery was used to identify dry watercourses in the desert to the west of the Nile. A canyon, now filled by surface drift, represents the Eonile that flowed during 23–5.3 million years before present. The Eonile transported clastic sediments to the Mediterranean; several natural gas fields have been discovered within these sediments. During the late- Miocene Messinian salinity crisis , when

Sikanni Chief River - Misplaced Pages Continue

2752-486: The Ethiopian Highlands. The Blue Nile flows about 1,400 kilometres to Khartoum, where the Blue Nile and White Nile join to form the Nile. Ninety percent of the water and ninety-six percent of the transported sediment carried by the Nile come from the Atbarah and Blue Nile, both of which originate in Ethiopia, with fifty-nine percent of the water coming from the Blue Nile. The erosion and transportation of silt only occurs during

2838-474: The Mediterranean Sea was a closed basin and evaporated to the point of being empty or nearly so, the Nile cut its course down to the new base level until it was several hundred metres below world ocean level at Aswan and 2,400 m (7,900 ft) below Cairo. This created a very long and deep canyon which was filled with sediment after the Mediterranean was recreated. At some point the sediments raised

2924-570: The Middle East and Africa, and described being told of the source of the Nile in Abyssinia (Ethiopia). Later in the 15th and 16th centuries, travelers to Ethiopia visited Lake Tana and the source of the Blue Nile in the mountains south of the lake. Supposedly, Paolo Trevisani ( c.  1452 –1483), a Venetian traveller in Ethiopia, wrote a journal of his travels to the origin of the Nile that has since been lost. Although James Bruce claimed to be

3010-510: The Nile carries little water (5% of that of the Congo River , for example). The Nile basin is complex, and because of this, the discharge at any given point along the main stem depends on many factors including weather, diversions, evaporation and evapotranspiration , and groundwater flow. Upstream from Khartoum (to the south), the river is known as the White Nile , a term also used in

3096-399: The Nile is the primary water source of Egypt, Sudan and South Sudan. The Nile is an important economic driver supporting agriculture and fishing. The Nile has two major tributaries : the White Nile and the Blue Nile . The White Nile is traditionally considered to be the headwaters stream. However, the Blue Nile is the source of most of the water of the Nile downstream, containing 80% of

3182-653: The Nile near the southern point of the Great Bend. The Nile has been the lifeline of civilization in Egypt since the Stone Age , with most of the population and all of the cities of Egypt developing along those parts of the Nile valley lying north of Aswan. However, the Nile used to run much more westerly through what is now Wadi Hamim and Wadi al Maqar in Libya and flow into the Gulf of Sidra . As

3268-515: The Nile since ancient times. A tune, Hymn to the Nile , was created and sung by the ancient Egyptian peoples about the flooding of the Nile River and all of the miracles it brought to Ancient Egyptian civilization. Water buffalo were introduced from Asia, and the Assyrians introduced camels in the 7th century BCE. These animals were raised for meat and were domesticated and used for ploughing—or in

3354-625: The Nile. When in flood the Sobat carries a large amount of sediment, adding greatly to the White Nile's color. The Yellow Nile is a former tributary that connected the Ouaddaï highlands of eastern Chad to the Nile River Valley c.  8000 to c.  1000 BCE . Its remains are known as the Wadi Howar . The wadi passes through Gharb Darfur near the northern border with Chad and meets up with

3440-541: The Sudd wetlands of South Sudan, the upper reaches of the White Nile remained largely unknown to the ancient Greeks and Romans. Vitruvius thought that source of the Nile was in Mauritania, on the "other" (south) side of the Atlas Mountains . Various expeditions failed to determine the river's source. Agatharchides records that in the time of Ptolemy II Philadelphus , a military expedition had penetrated far enough along

3526-598: The US, interstate compacts ) or other political entities in a particular drainage basin to manage the body or bodies of water into which it drains. Examples of such interstate compacts are the Great Lakes Commission and the Tahoe Regional Planning Agency . In hydrology , the drainage basin is a logical unit of focus for studying the movement of water within the hydrological cycle . The process of finding

Sikanni Chief River - Misplaced Pages Continue

3612-537: The White Nile at Lake Kawaki Malakal, just below the Sobat River, is 924 m /s (32,600 cu ft/s); the peak flow is approximately 1,218 m /s (43,000 cu ft/s) in October and minimum flow is about 609 m /s (21,500 cu ft/s) in April. This fluctuation is caused by the substantial variation in the flow of the Sobat, which has a minimum flow of about 99 m /s (3,500 cu ft/s) in March and

3698-798: The White Nile, even after centuries of exploration, remains in dispute. The most remote source that is indisputably a source for the White Nile is the Kagera River ; however, the Kagera has tributaries that are in contention for the farthest source of the White Nile. Two start in Burundi: the Ruvyironza River (also known as the Luvironza) and the Rurubu River . In addition, in 2010, an exploration party in Rwanda went to

3784-444: The 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 day as he crossed the sky. Thus, all tombs were west of the Nile, because the Egyptians believed that in order to enter the afterlife, they had to be buried on the side that symbolized death. As the Nile was such an important factor in Egyptian life,

3870-482: The ancient calendar was even based on the three cycles of the Nile. These seasons, each consisting of four months of thirty days each, were called Akhet , Peret , and Shemu . Akhet, which means inundation, was the time of the year when the Nile flooded, leaving several layers of fertile soil behind, aiding in agricultural growth. Peret was the growing season, and Shemu, the last season, was the harvest season when there were no rains. Owing to their failure to penetrate

3956-406: The basin, it can form tributaries that change the structure of the land. There are three different main types, which are affected by the rocks and ground underneath. Rock that is quick to erode forms dendritic patterns, and these are seen most often. The two other types of patterns that form are trellis patterns and rectangular patterns. Rain gauge data is used to measure total precipitation over

4042-411: The camels' case, carriage. Water was vital to both people and livestock. The Nile was also a convenient and efficient means of transportation for people and goods. The Nile was also an important part of ancient Egyptian spiritual life. Hapi was the god of the annual floods, and both he and the pharaoh were thought to control the flooding. The Nile was considered to be a causeway from life to death and

4128-406: The central part of the basin may still be subsiding. The White Nile Rift system, although shallower than the Bahr el Arab rift , is about 9 kilometers (5.6 mi) deep. Geophysical exploration of the Blue Nile Rift System estimated the depth of the sediments to be 5–9 kilometers (3.1–5.6 mi). These basins were not interconnected until their subsidence ceased, and the rate of sediment deposition

4214-471: The confluence with the Blue Nile the only major tributary is the Atbarah River , also known as the Red Nile. Roughly halfway to the sea, it originates in Ethiopia north of Lake Tana , and is around 800 kilometers (500 mi) long. The Atbarah flows only while there is rain in Ethiopia and dries very rapidly. During the dry period of January to June, it typically dries up north of Khartoum . The Blue Nile ( Amharic : ዓባይ , ʿĀbay ) springs from Lake Tana in

4300-412: The course of the Blue Nile to determine that the summer floods were caused by heavy seasonal rainstorms in the Ethiopian Highlands, but no European of antiquity is known to have reached Lake Tana. The Tabula Rogeriana depicted the source as three lakes in 1154. Europeans began to learn about the origins of the Nile in the 14th century when the Pope sent monks as emissaries to Mongolia who passed India,

4386-492: The development of Egyptian civilization. Because the river overflowed its banks annually and deposited new layers of silt, the surrounding land was very fertile. The Ancient Egyptians cultivated and traded wheat, flax , papyrus and other crops around the Nile. Wheat was a crucial crop in the famine-plagued Middle East. This trading system secured Egypt's diplomatic relationships with other countries and contributed to economic stability. Far-reaching trade has been carried on along

SECTION 50

#1732873104810

4472-430: The discharge of water from a basin may be made by a stream gauge located at the basin's outlet. Depending on the conditions of the drainage basin, as rainfall occurs some of it seeps directly into the ground. This water will either remain underground, slowly making its way downhill and eventually reaching the basin, or it will permeate deeper into the soil and consolidate into groundwater aquifers. As water flows through

4558-441: The drainage area is dependent on the soil type. Certain soil types such as sandy soils are very free-draining, and rainfall on sandy soil is likely to be absorbed by the ground. However, soils containing clay can be almost impermeable and therefore rainfall on clay soils will run off and contribute to flood volumes. After prolonged rainfall even free-draining soils can become saturated , meaning that any further rainfall will reach

4644-642: The drainage basin to the mouth, and may accumulate there, disturbing the natural mineral balance. This can cause eutrophication where plant growth is accelerated by the additional material. Because drainage basins are coherent entities in a hydrological sense, it has become common to manage water resources on the basis of individual basins. In the U.S. state of Minnesota , governmental entities that perform this function are called " watershed districts ". In New Zealand, they are called catchment boards. Comparable community groups based in Ontario, Canada, are called conservation authorities . In North America, this function

4730-402: The dry season the natural discharge of the Blue Nile can be as low as 113 m /s (4,000 cu ft/s), although upstream dams regulate the flow of the river. During the wet season, the peak flow of the Blue Nile often exceeds 5,663 m /s (200,000 cu ft/s) in late August (a difference of a factor of 50). Before the placement of dams on the river the yearly discharge varied by

4816-432: The eastern coast of Africa, the coasts of the Red Sea and the Persian Gulf , the Indian subcontinent , Burma, and most parts of Australia . The five largest river basins (by area), from largest to smallest, are those of the Amazon (7 million km ), the Congo (4 million km ), the Nile (3.4 million km ), the Mississippi (3.22 million km ), and the Río de la Plata (3.17 million km ). The three rivers that drain

4902-499: The entire river system. Thus, the name may derive from Ancient Egyptian expression n ꜣ r ꜣ w-ḥ ꜣ w(t) (lit. 'the mouths of the front parts'), which referred specifically to the branches of the Nile transversing the Delta, and would have been pronounced ni-lo-he in the area around Memphis in the 8th century BCE. Hesiod at his Theogony refers to Nilus (Νεῖλος) as one of the Potamoi (river gods), son of Oceanus and Tethys . Another derivation of Nile might be related to

4988-441: The first European to have visited the headwaters, modern writers give the credit to the Jesuit Pedro Páez . Páez's account of the source of the Nile is a long and vivid account of Ethiopia. It was published in full only in the early 20th century, although it was featured in works of Páez's contemporaries, including Baltazar Téllez, Athanasius Kircher and Johann Michael Vansleb . Europeans had been resident in Ethiopia since

5074-459: The great lakes. Believing he had found the source of the Nile on seeing this "vast expanse of open water" for the first time, Speke named the lake after Queen Victoria . Burton, recovering from illness and resting further south on the shores of Lake Tanganyika , was outraged that Speke claimed to have proven his discovery to be the true source of the Nile when Burton regarded this as still unsettled. A quarrel ensued which sparked intense debate within

5160-412: The greatest portion of western Sub-Saharan Africa , as well as Western Sahara and part of Morocco . The two major mediterranean seas of the world also flow to the Atlantic. The Caribbean Sea and Gulf of Mexico basin includes most of the U.S. interior between the Appalachian and Rocky Mountains , a small part of the Canadian provinces of Alberta and Saskatchewan , eastern Central America ,

5246-435: The ground and along rivers it can pick up nutrients , sediment , and pollutants . With the water, they are transported towards the outlet of the basin, and can affect the ecological processes along the way as well as in the receiving water body . Modern use of artificial fertilizers , containing nitrogen (as nitrates ), phosphorus , and potassium , has affected the mouths of drainage basins. The minerals are carried by

SECTION 60

#1732873104810

5332-422: The ground at its terminus, the area can go by several names, such playa, salt flat, dry lake , or alkali sink . The largest endorheic basins are in Central Asia , including the Caspian Sea , the Aral Sea , and numerous smaller lakes. Other endorheic regions include the Great Basin in the United States, much of the Sahara Desert , the drainage basin of the Okavango River ( Kalahari Basin ), highlands near

5418-417: The islands of the Caribbean and the Gulf, and a small part of northern South America. The Mediterranean Sea basin, with the Black Sea , includes much of North Africa , east-central Africa (through the Nile River ), Southern , Central, and Eastern Europe , Turkey , and the coastal areas of Israel , Lebanon , and Syria . The Arctic Ocean drains most of Western Canada and Northern Canada east of

5504-413: The larger part of which is in Egypt. Below the Aswan Dam , at the northern limit of Lake Nasser, the Nile resumes its historic course. North of Cairo , the Nile splits into two branches (or distributaries) that feed the Mediterranean: the Rosetta Branch to the west and the Damietta to the east, forming the Nile Delta . The annual sediment transport by the Nile in Egypt has been quantified. Below

5590-434: The late 15th century, and one of them may have visited the headwaters even earlier without leaving a written trace. The Portuguese João Bermudes published the first description of the Tis Issat Falls in his 1565 memoirs, compared them to the Nile Falls alluded to in Cicero 's De Republica . Jerónimo Lobo describes the source of the Blue Nile, visiting shortly after Pedro Páez. Telles also uses his account. The White Nile

5676-402: The main Nile during the 70,000–80,000 years B.P. wet period. The White Nile system in Bahr El Arab and White Nile Rifts remained a closed lake until the connection of the Victoria Nile to the main system some 12,500 years ago during the African humid period . The Greek historian Herodotus wrote that "Egypt was the gift of the Nile". An unending source of sustenance, it played a crucial role in

5762-409: The most water, from most to least, are the Amazon, Ganges , and Congo rivers. Endorheic basin are inland basins that do not drain to an ocean. Endorheic basins cover around 18% of the Earth's land. Some endorheic basins drain to an Endorheic lake or Inland sea . Many of these lakes are ephemeral or vary dramatically in size depending on climate and inflow. If water evaporates or infiltrates into

5848-404: The present course of the Nile in Egypt and Sudan. Rushdi Said postulates that Egypt supplied most of the waters of the Nile during the early part of its history. The other theory is that the drainage from Ethiopia via rivers equivalent to the Blue Nile, the Atbara and the Takazze flowed to the Mediterranean via the Egyptian Nile since well back into Tertiary times. Salama suggests that during

5934-418: The rainfall on the area of land included in its polygon. These polygons are made by drawing lines between gauges, then making perpendicular bisectors of those lines form the polygons. The isohyetal method involves contours of equal precipitation are drawn over the gauges on a map. Calculating the area between these curves and adding up the volume of water is time-consuming. Isochrone maps can be used to show

6020-572: The responsibility of the countries sharing it. Nile Basin Initiative , OMVS for Senegal River , Mekong River Commission are a few examples of arrangements involving management of shared river basins. Management of shared drainage basins is also seen as a way to build lasting peaceful relationships among countries. The catchment is the most significant factor determining the amount or likelihood of flooding . Catchment factors are: topography , shape, size, soil type, and land use (paved or roofed areas). Catchment topography and shape determine

6106-414: The river flows into the Mediterranean Sea at Alexandria . Egyptian civilization and Sudanese kingdoms have depended on the river and its annual flooding since ancient times. Most of the population and cities of Egypt lie along those parts of the Nile valley north of the Aswan Dam . Nearly all the cultural and historical sites of Ancient Egypt developed and are found along river banks. The Nile is, with

6192-461: The river rather than being absorbed by the ground. If the surface is impermeable the precipitation will create surface run-off which will lead to higher risk of flooding; if the ground is permeable, the precipitation will infiltrate the soil. Land use can contribute to the volume of water reaching the river, in a similar way to clay soils. For example, rainfall on roofs, pavements , and roads will be collected by rivers with almost no absorption into

6278-520: The riverbed sufficiently for the river to overflow westward into a depression to create Lake Moeris . Lake Tanganyika drained northwards into the Nile until the Virunga Volcanoes blocked its course in Rwanda. The Nile was much longer at that time, with its furthest headwaters in northern Zambia. The currently existing Nile first flowed during the former parts of the Würm glaciation period. Affad 23

6364-407: The scientific community and interest by other explorers keen to either confirm or refute Speke's discovery. British explorer and missionary David Livingstone pushed too far west and entered the Congo River system instead. It was ultimately Welsh-American explorer Henry Morton Stanley who confirmed Speke's discovery, circumnavigating Lake Victoria and reporting the great outflow at Ripon Falls on

6450-575: The sea level rose at the end of the most recent ice age , the stream which is now the northern Nile captured the ancestral Nile near Asyut . This change in climate also led to the current extents of the Sahara desert, around 3400 BCE. The Giza pyramid complex originally overlooked a branch of the Nile that no longer exists. This branch was highest during the African Humid Period . The existing Nile has five earlier phases: Flowing north from

6536-528: The soil. The Nile no longer floods in Egypt since the completion of the Aswan Dam in 1970. An anabranch river, the Bahr el Zeraf , flows out of the Nile's Bahr al Jabal section and rejoins the White Nile. The flow rate of the Bahr al Jabal at Mongalla is almost constant throughout the year and averages 1,048 m /s (37,000 cu ft/s). After Mongalla, the Bahr Al Jabal enters the enormous swamps of

6622-418: The speed with which the runoff reaches a river. A long thin catchment will take longer to drain than a circular catchment. Size will help determine the amount of water reaching the river, as the larger the catchment the greater the potential for flooding. It is also determined on the basis of length and width of the drainage basin. Soil type will help determine how much water reaches the river. The runoff from

6708-510: The term Nil ( Sanskrit : नील , romanized :  nila ; Egyptian Arabic : نيلة ), which refers to Indigofera tinctoria , one of the original sources of indigo dye . Another may be Nymphaea caerulea , known as "The Sacred Blue Lily of the Nile", which was found scattered over Tutankhamun 's corpse when it was excavated in 1922. Another possible etymology derives from the Semitic term Nahal , meaning "river". Old Libyan has

6794-422: The term lilu , meaning water (in modern Berber ilel ⵉⵍⴻⵍ means sea ). With a total length of about 6,650 km (4,130 mi) between the region of Lake Victoria and the Mediterranean Sea , the Nile is among the longest rivers on Earth. The drainage basin of the Nile covers 3,254,555 square kilometers (1,256,591 sq mi), about 10% of the area of Africa. Compared to other major rivers, though,

6880-415: The time taken for rain to reach the river, while catchment size, soil type, and development determine the amount of water to reach the river. Generally, topography plays a big part in how fast runoff will reach a river. Rain that falls in steep mountainous areas will reach the primary river in the drainage basin faster than flat or lightly sloping areas (e.g., > 1% gradient). Shape will contribute to

6966-477: The time taken for runoff water within a drainage basin to reach a lake, reservoir or outlet, assuming constant and uniform effective rainfall. Drainage basins are the principal hydrologic unit considered in fluvial geomorphology . A drainage basin is the source for water and sediment that moves from higher elevation through the river system to lower elevations as they reshape the channel forms. Drainage basins are important in ecology . As water flows over

7052-546: The water and silt . The White Nile is longer and rises in the Great Lakes region. It begins at Lake Victoria and flows through Uganda and South Sudan. The Blue Nile begins at Lake Tana in Ethiopia and flows into Sudan from the southeast. The two rivers meet at the Sudanese capital of Khartoum . The northern section of the river flows north almost entirely through the Nubian Desert to Cairo and its large delta , and

7138-473: The word ⲫⲓⲁⲣⲟ , pronounced piaro ( Sahidic ) or phiaro ( Bohairic ), means "the river" (lit. p(h).iar-o "the.canal-great"), and comes from the same ancient name. In Nobiin , the river is called Áman Dawū , meaning "the great water". In Luganda , the river is called Kiira or Kiyira . In Runyoro , it is called Kihiira . In Egyptian Arabic , the Nile is called en-Nīl , while in Standard Arabic it

7224-692: The world's land drains to the Atlantic Ocean . In North America , surface water drains to the Atlantic via the Saint Lawrence River and Great Lakes basins, the Eastern Seaboard of the United States, the Canadian Maritimes , and most of Newfoundland and Labrador . Nearly all of South America east of the Andes also drains to the Atlantic, as does most of Western and Central Europe and

7310-562: Was enough to fill and connect them. The Egyptian Nile connected to the Sudanese Nile, which captures the Ethiopian and Equatorial headwaters during the current stages of tectonic activity in the Eastern, Central and Sudanese Rift systems. The connection of the different Niles occurred during cyclic wet periods. The Atbarah overflowed its closed basin during the wet periods that occurred about 100,000 to 120,000 years ago. The Blue Nile connected to

7396-582: Was even less understood. The ancients mistakenly believed that the Niger River represented the upper reaches of the White Nile. For example, Pliny the Elder writes that the Nile had its origins "in a mountain of lower Mauretania ", flowed above ground for "many days" distance, then went underground, reappeared as a large lake in the territories of the Masaesyli , then sank again below the desert to flow underground "for

#809190