Nile

African Great Lakes

The African Great Lakes region contains the source of the Nile river as well as several large lakes that are part of the Nile river system: Lake Victoria, Lake Albert, Lake George, and Lake Edward.^[29] The source of the Nile is the Rukarara River within Rwanda's Nyungwe National Park,^[2] and it leads to the Kagera River,^[l] which drains into Lake Victoria.^[5] Although it is a large lake – the second-largest freshwater lake in the world^[m] – Lake Victoria is relatively shallow. The Nile river first assumes the name "Nile" where Lake Victoria empties on its north side: the course from there to Lake Albert is called the Victoria Nile.^[5] A pair of waterfalls – Ripon Falls and Owen Falls – were located where the Nile exits Lake Victoria, but have both been submerged by the construction of the Nalubaale dam. After Bujagali Falls and Bujagali Power Station, the Victoria Nile empties into Lake Kyoga. After exiting Lake Kyoga, the river is joined by the River Kafu tributary, then passes over Murchison Falls and flows into Lake Albert. Unlike Lake Victoria, Lake Albert is a deep lake surrounded by mountains. The river exits Lake Albert on its north shore, where it is called the Albert Nile; this stretch of the river is relatively flat and broad, and suitable for navigation by steamboats.^[30]

Mountain Nile

The second region of the Nile Basin, proceeding downstream, is the Mountain Nile (Arabic: Bahr al Jabal).^[31] This region begins near the town of Nimule and extends to Lake No, and is entirely within South Sudan. After passing through Nimule, the river goes through the Fula Rapids and on to Juba – the capital city of South Sudan. After Juba, the Nile passes through the town of Bor, then enters the Sudd, a large swamp located in a flat plain. The slope of the ground in the Sudd is only 1:13,000, so the river slows down and widens. Lush vegetation, including sedges, papyrus, and common water hyacinth (an invasive species) clog the waterways and make navigation difficult. At the downstream edge of the Sudd swamp, the Nile is joined by the Bahr el Ghazal River (Arabic: "gazelle river") a tributary flowing from the west. This confluence happens in Lake No.^[30]

White Nile region

Continuing downstream, the third region of the Nile Basin is the White Nile region.^[n] About 140 km after Lake No, the swamps diminish near the city of Malakal, and the river enters a long, placid stretch extending to Khartoum, where it is joined by the Blue Nile near Khartoum, the capital of Sudan.^[5]

Main Nile

The fourth region of the Nile Basin – the main Nile^[o] – extends from Khartoum to Cairo, the capital of Egypt. Soon after leaving Khartoum, the river goes enters the Sabaloka Game Reserve and goes through the sixth (and furthest upstream) of the renowned six cataracts of the Nile. The Atbarah River – a major tributary – joins the Nile, which then follows a large S-shape curve to the west. Four more cataracts are encountered in this large S-curve, which render the river unnavigable, although ships may travel between the cataracts. The river then enters a large reservoir, Lake Nasser.^[p] This lake – the world's second largest man-made lake – was formed when the Aswan High Dam was built in Egypt, and inundates more than 480 km of the Nile river. The Aswan Low Dam – older and smaller than the High Dam – lies beneath the Aswan High Dam, near the location of the first Nile cataract (now submerged). From these dams, the Nile flows about 800 km through a limestone plateau, bordered by large amounts of irrigated farmland, until it reaches Cairo.^[30]

Nile Delta

The fifth, and final, region encompassing the Nile river is the Nile Delta, a large triangular river delta (about 22,000 km^2[35]) that extends from Cairo to the Mediterranean Sea.^[5] The river splits into two major distributaries (channels) within the delta: the Rosetta branch and the Damietta branch. The width of the underwater portion of the Nile delta is 320 km, and it reaches into the Mediterranean Sea to a depth of 1,800 m. The total volume of the delta (including the submerged portions) is about 150,000 km³. The delta was created over several million years, built-up from sediment carried down the river from upstream.^[36] Since the Aswan High Dam was completed in 1970, the delta has begun to shrink due erosion caused by currents in the Mediterranean Sea. In the past, erosion was balanced by new soils arriving in the form of sediment carried by the river; but the dam traps sediment in its reservoir, preventing new soil from reaching the delta.^[37][q]

The final two regions of the Nile Basin are the Blue Nile basin and the Atbarah River basin,^[5] both discussed in the section on Tributaries.

Tributaries

The longest course of the Nile, which includes the White Nile tributary, has several other tributaries that feed into it.

Blue Nile

Main article: Blue Nile

The Blue Nile springs from hills in Ethiopia^[25] where it originates as a stream named Abay near the town of Gish Abay: Gish in an Amharic word meaning 'source', and Abay is the name of the stream.^[25][38] Gish Abay flows into Lake Tana, a large, shallow lake, which has a single outflow where it adopts the 'Blue Nile' name. The Blue Nile travels south, then north passing through South Sudan into Sudan, where it joins with the White Nile at Khartoum to form the main Nile.^[38] Along its course, the Blue Nile generates electricity at several hydro power plants, including the Tis Abay hydropower project at the Blue Nile Falls, the Grand Ethiopian Renaissance Dam near the border between Ethiopia and South Sudan, the Roseires Dam near town of Ad Damazin, and the Sennar Dam.^[39] The size of the Blue Nile's drainage basin is over 306,000 square km.^[40]

Flow and floods

Although the Nile is the longest river in the world, it is far from having the largest discharge. Its flow – about 87 km³ per year^[b] – is small compared to other major rivers. The Nile's discharge is only about 1% of the Amazon, 6% of the Congo, and 12% of the Yangtze.^[49][s]

The annual contributions to the main Nile from the three primary tributaries are: 54% from the Blue Nile, 32% from the White Nile (including contributions from the Bahr el Ghazal and Sobat tributaries), and 14% from the Atabarah.^[50] Thus, the proportion of water from the Ethiopian Highlands is about 68% (the Blue Nile and Atbarah arise in Ethiopia), and the proportion from the African Great Lakes region (source of most of the White Nile) is about 32%.^[50][t]

The highlands of the White Nile and Blue Nile both experience seasonal rain, but the White Nile's flow into the main Nile is much more constant than the Blue Nile.^[5] This is due to the many lakes and wetlands on the White Nile, which moderate the cyclic effects of seasonal rainfall.^[53] The White Nile passes through the Sudd swamps before it reaches the Blue Nile; about half the water flowing into the Sudd is lost to evaporation before it flows out.^[54]

In contrast, the Blue Nile has tremendous variability in its flow: it floods between July and October, due to summer monsoon rains.^[5] The waters of the Blue Nile are so substantial during the summer and autumn, that the White Nile backs-up during this time at the confluence.^[55] During the summer floods, the contributions to the main Nile are about 70% from the Blue Nile, about 20% from the Atbarah, and about 10% from the White Nile.^[5] At the peak of the flood, the daily flow into Lake Nasser is about 0.71 km³, about three times the annual daily average of 0.23 km³ per day.^[56]

As the Blue Nile flow diminishes in the winter, the pent-up waters of the White Nile increase their flow past Khartoum.^[57] In April and May, the White Nile supplies about 80% of the main Nile's water. Thus, the areas downstream of Khartoum receive a steady (not to say constant) flow that made irrigation possible year-round.^[57]

Prior to the construction of dams on the Nile, the variability of flow in Egypt was significant: higher in the summer/fall; lower in the winter/spring. However, following the construction of the Aswan High Dam – which created a reservoir that can hold about two years of river flow – the flow downstream from that dam is now more constant year-round.^[58][u]

Sediment transport

The Nile carries sediment downstream. The movement of sediment is classified as suspended sediment (particles suspended in the water) or bedload (sediment on the river bottom that rolls or tumbles downstream).^[60]

Ninety-seven percent of the transported sediment carried by the Nile comes from the Atbarah and Blue Nile, both of which originate in Ethiopia.^[61] The erosion and transportation of silt only occurs during the Ethiopian rainy season when rainfall is especially high in the Ethiopian Highlands; the rest of the year, the major rivers draining Ethiopia into the Nile have a weaker flow.^[5] The cumulative amount of rock eroded in the past 30 million years from the Ethiopia headwaters of the Nile is about 102,000 km³, which is roughly comparable to the volume of the soil in the Nile Delta (including the underwater portion) which is about 150,000 km³.^[62]

Sediment carried by the Nile, or its tributaries, into a reservoir has the potential to settle in the reservoir and reduce the storage capacity of the reservoir. Sediment accumulated behind the Sennar Dam, Roseires Dam (on the Blue Nile), and Khashm el Girba Dam (on the Atbarah) has significantly reduced the storage capacity of their reservoirs since they were built.^[63]

Annual sediment transport measured at several locations are listed below.^[64] These measurements conducted at various dates, ranging from 1997 to 2019. The bedload percentages are the ratio of bedload sediment to total (bedload and suspended) sediment. These data were collected before the construction of the Grand Ethiopian Renaissance Dam, which has a significant impact on sediment loads downstream of the dam.^[64]

• Gilgel Abay, Ethiopia : 7.6 million tonnes of suspended, and an additional 0.7% of bedload
• El Deim (at the border of Ethiopia and Sudan): 140 million tonnes^[63]
• Aswan, Egypt: 0.14 million tonnes of suspended, and an additional 28% of bedload
• Beni Sweif, Egypt: 0.5 million tonnes of suspended, and an additional 20% of bedload
• Qena, Egypt: 0.27 million tonnes of suspended, and an additional 27% of bedload
• Sohag, Egypt: 1.5 million tonnes of suspended, and an additional 13% of bedload

Water sources and sinks

Some regions in the Nile Basin contribute to the river's flow, and other regions take from the river. A region is a 'source' if the region is contributing water to the rivers passing through; conversely, a region is a 'sink' if the region is removing water from the rivers passing through.^[65][v] Identifying sources and sinks is important to scientists that study water movement (hydrology), as well as policy makers that negotiate water sharing issues.^[66]

The regions of the Nile basin that are water sources are the upstream areas including the Ethiopian Highlands and the African Great Lakes region. The water sink areas are generally found in the downstream regions, including South Sudan, Sudan, and Egypt.^[67][w]

The water balance methodology is employed to determine which regions are sources and which are sinks. Water balance is a hydrological principle that states that the water entering a region is balanced by the water leaving a region.^[68][x] The water balance of a region can be represented by the following equation:^[68][y]

${\displaystyle P=ET+\Delta S+D+Q}$

In this formula, the precipitation (P) received is equal to the sum of the water losses: evaporation and transpiration (ET), groundwater recharge (${\displaystyle \Delta S}$), lake-filling (D), and net streamflow (Q). Evaluating this formula will indicate if a region is a source or a sink. Generally, a region is a source if the net streamflow is positive; conversely, a region is a sink if the net streamflow is negative.^[65]

Nilometers

Measurements of the Nile's flow has always been essential to help Egyptians manage their safety and irrigation. Simple gauges, called nilometers, have been used to measure the level of the Nile for thousands of years.^[74] An important nilometer has been in use on Roda Island since at least 622 AD; Egyptians kept records of maximum and minimum river levels from that gauge until 1921.^[73] Modern gauges to measure the river level began to be installed in the 1860s, and gauges that measured the river's current – which provide more accurate flow information – were installed beginning in 1900.^[73]

Animals

The Hippopotamus amphibius is a mammal that lives in Nile Basin and spends a large amount of time in the water. This specimen is near Lake Edward, one of the lakes that feed the Nile.

Fish are abundant in the Nile Basin: the total number of species is estimated at over 800. In the river alone, 128 species are found, belonging to 27 families.^[75] The majority of species belong to the four families: Cichlidae (cichlids), Cyprinidae (carp), Mormyridae (elephantfish), and Mochokidae (catfish).^[76] A large number of Cichlid species are found in the African Great Lakes.^[75]

In addition to fish, animals that sometimes reside in the Nile's waters include hippos, crocodiles, and African buffalo. Other water dwellers include molluscs, crabs, and shrimp.^[77] Many animals live in the ecosystems along the river banks, including elephants, antelope, and giraffes.^[77] Snails found in Nile lakes carry parasitic flatforms – known as blood flukes – which are responsible for the schistosomiasis disease that afflicts livestock and humans.^[78]

Birds that live on or near the Nile include herons, kingfishers, ospreys, and various kinds of storks – such as shoebills.^[77] Some of the bird species are endemic to the Nile basin (such as blue-winged goose), while other species have a cosmopolitan distribution (such as moorhen and osprey).^[79] Several species of heron, ducks, geese, and egrets live in the basin year-round, and 14 species of ducks and geese arrive only for winter residence.^[79] Of the gulls and terns in the basin, the vast majority are migratory. During the past thousand years, the ranges of some species have been reduced, probably due to human encroachment on habitat.^[79]

Plants

The Great Lakes region of the Nile Basin includes plants such as the water lily, papyrus, and water hyacinth. The water hyacinth in an invasive species, and has adversely impacted the populations of native species in Lake Kyoga.^[81] Plants common in the Sudd swamp include species that thrive in deep flooding such as Vossia, hippo grass, reed mace, ambatch, and papyrus. The Sudd also hosts species that thrive in shallow flooding such as Oryza, antelope grass, and Phragmites.^[82]

Pollution

Historically, the water of the Nile was noted for being drinkable, but in the late 20th century, it became less healthy in certain areas.^[83] Lake Tana is polluted with industrial pollution; portions of the river near population centers (such as Khartoum and Cairo) are polluted with industrial pollutants and sewage; ships contribute pollutants to the waters; and industrial plants in Egypt dump waste into the river.^[84]

Sources of pollution in the Nile include agricultural, industrial, and household waste. There are 36 industries that discharge their pollution sources directly into the Nile, and 41 into irrigation canals. These types of industries are: chemical, electrical, engineering, fertilizers, food, metal, mining, oil and soap, pulp and paper, refractory, textile and wood. There are over 90 agricultural drains that discharge into the Nile that also include industrial wastewater.^[85]

River pollution is most pronounced between Aswan and the Mediterranean Sea. The pollution there comes from human activities, agricultural runoff, and industrial waste. The river delta contains Egypt's primary oil and gas production facilities, and the chemical industry in the delta is the single largest contributor of toxic waste to the Nile. Concentrations of pollutants increase as the river flows downstream, due to the cumulative effects of pollution sources.^[86] The Nile delta has relatively high levels of heavy metal concentrations. The delta is susceptible to accumulated concentrations because of poor flushing actions, exacerbated by a flat topography and heavy silting in the riverbed.^[87] The northeast region of the delta is the most polluted part of the river in Egypt, and has a high incidence of pancreatic cancer, which may be related to high levels of heavy metals and organchlorine pesticides found in the soil and water.^[88]

In the late 20th century, Lake Victoria experienced increased eutrophication resulting in excessive plant growth, which depletes oxygen levels in the water. The eutrophication is due to human activity, deforestation, and poor agricultural practices, and has caused algal blooms and a rapid proliferation of water hyacinth, which have disrupted the ecosystem.^[89]

Conservation and human impact

The Nile Basin was relatively wet and humid from 15 KYA (thousand years ago) to 5 KYA, which enabled the start of large-scale agriculture in the Nile Basin around 5 KYA. The growth of agriculture has had an increasing impact on the environment since then, leading to widespread deforestation and soil erosion.^[90] The impacts were worsened by drier conditions in Africa that started about 4 KYA. These arid conditions led to famines and social disruption, and also to increased environmental degradation.^[90]

Several species of animals have become extinct in the Nile Basin due to human activity. The sacred ibis was important in the ancient Egyptian relgion, and millions of the ibis were ritually sacrificed, leading to the eventual extinction of the species in Egypt. The bird remains common in central and southern Africa.^[91]

The Nile perch was native to several places in Africa, including the Congo, but was not present in the Nile river or its lakes until it was surreptitiously introduced to Lake Victoria in the 1950s to create a fishing stock.^[92][al] The Nile Perch caused the extinction of over 500 species of cichlids in Lake Victoria, which scientist Les Kaufman described as the first mass extinction of vertebrates that scientists have had the opportunity to observe.^[92][am] The Nile Perch also led to increased deforestation, because firewood was required to process the fish.^[94]

The satellite lakes of Lake Kyoga are potentially important for future conservation efforts, because they contain at least 60 species of haplochromines, and have not yet been invaded by the Nile Perch.^[78]

Climate and climate change

This map shows the Köppen climate classification zones in the Nile Basin. The northern part of the basin is a hot, dry desert (Bwh) while the south is cooler and wetter (C and A zones).^[95]

The climate of the Nile Basin is defined by a pronounced gradient: very dry in the north, becoming progressively wetter to the south.^[96] The basin can be divided into nine distinct rainfall regions: the northern regions (Egypt and Sudan) are very dry all year; the middle regions (including Ethiopia) have strong peaks of rainfall in the summer; and the southern regions (around Lake Victoria) have two rainfall peaks – in spring and fall.^[97] The majority of the rainfall in the Nile Basin is associated with the summer monsoon.^[98]

The Nile Basin is experiencing climate changes related to the increasing prevalence of greenhouse gasses in the atmosphere.^[99] Projections for the 21st century include a 2 to 4 °C increase.^[99] The Blue Nile basin in Ethiopia has been experiencing significant changes in temperature and precipitation since the 1970s. In a review published in 2024, scientists predicted that temperatures would continue to rise. Rainfall is fluctuating and impacting crop production, but future trends are uncertain.^[100]

Models of the future climate in the North Africa and Middle East region predict increasing dryness and drought, and increasing variability of precipitation.^[101] The Nile Delta is particularly vulnerable, and the combined action of sea level rise and lack of sediment replenishment (due to dams on the Nile) may cause one third of the Nile Delta to disappear within the next century.^[102]

Pre-Egyptian Nile

The first stage of the Nile's geological history is the Pre-Egyptian Nile, which occupies the period before 6 million years ago (MYA). In that era, rivers in Egypt generally flowed from the region near the Red Sea towards the west, rather than to the north (as the modern Nile does).^[105]

Ancestral Egyptian Nile

The second stage of the Nile's geological history is the Ancestral Egyptian Nile, which spanned the era from 6 MYA to 12 thousand years ago (KYA)). In this period a major river in Egypt formed and began to flow north to the Mediterranean Sea, establishing the ancestor of the modern Nile.^[106] A critical event of this era was the Messinian salinity crisis, which lasted from roughly 6 MYA to 5 MYA. During this crisis, the Strait of Gibraltar was closed, and the Atlantic ocean could no longer fill the Mediterranean Sea, so the Sea evaporated. The empty Mediterranean caused the ancestor Nile to cut a deep gorge: eroding a canyon several hundred meters below world ocean level at Aswan, and 2,400 meters below at Cairo. This very long and very deep canyon later became filled with sediment after the Mediterranean was refilled.^[107]

Modern Nile

The third geological stage of the Nile is the modern Nile, which started around 12 KYA, when the Nile began to approximately follow its current course. This was the result of tectonic shifts (starting around 30 KYA) in the African Great Lakes region, which caused that region began to tilt northward and drain into Egypt. Around 12 KYA, the lakes Tana, Albert, and Victoria started to flow southward approximately into the current course of the Nile.^[108] At roughly the same time – about 15 KYA – the summer monsoon shifted and substantially increased rainfall in the area of Lake Victoria and Lake Albert.^[109] The flood levels of both the Blue Nile and White Nile have fluctuated over the past 12,000 years, with unusually high flood levels occurring every few thousand years.^[110]

Ancient Egyptian civilization

The Nile was central to every facet of ancient Egyptian civilization: it provided life through the crops it watered, and it caused death, when droughts caused crop failures and famine. The Nile encouraged the growth of science and government: irrigation, flood predictions and taxation all required new mathematical and administrative skills. Weather prediction and astronomy also developed as a consequence of the Egyptian's need to understand the river and its floods.^[112] The Nile led the Egyptians to build the world's first major dam – the Sadd el-Kafara ('dam of the infidels') – circa 2600 BC in an attempt to control flooding.^[113][ao] Some peoples migrated from the Sahara and southerly African regions into the early Nile Valley.^[114]

Ancient Egypt's southern boundary was – informally – at the river's first cataract (near Elephantine Island) because transportation beyond those rapids was difficult.^[115] The Egyptians were familiar with the course of the Nile upstream to the sixth cataract (present day Khartoum), but apparently were not familiar with the river course (nor its source) beyond that.^[116][ap]

The ancient Egyptian calendar was based on the flood cycle of the Nile. The year was divided into three seasons, each consisting of four months of thirty days each. The seasons were Akhet (literally, 'innundation'), Peret ('growing'), and Shemu ('harvest'). Akhet was the time of the year when the Nile flooded, leaving a new layer of fertile soil behind; Peret was the growing season; and Shemu was the harvest season when there were no rains.^[117]

Search for the source of the Nile

Since the times of the ancient Greeks, Europeans have been intensely curious about the source of the Nile and the origin of its floods, yet concrete knowledge about the source of the Nile was not discovered until the late Middle Ages.^[120] Herodotus was a Greek historian who visited Egypt in 457 BC, and traveled up the Nile to Aswan.^[ar] In the second century BC, the Greek scientist Eratosthenes drew a map of the Nile from the Mediterranean to Khartoum, and speculated that the source was a collection of lakes.^[121] Other Europeans that inquired or speculated about the source of the Nile included Ptolemy, Alexander the Great, Julius Caesar, Emperor Nero, and Pedro Tafur.^[122] In the 12th century, the Arabian geographer Muhammad al-Idrisi published a book Tabula Rogeriana which showed the Nile flowing from a large lake in Africa’s interior.^[122]

The source of the Blue Nile was established as a result of Portuguese interest in Ethiopia: the Jesuit missionary Pedro Páez visited the source – Gish Abay – in early 17th century, and wrote História da Ethiópia describing his time in Ethiopia. His accounts were not published until 1905, but other authors (including Jerónimo Lobo, James Bruce, and Athanasius Kircher) gave various estimates of the date of Páez's visit to Gish Abay – ranging from 1613 to 1618.^[123]

The source of the White Nile proved to be more difficult to establish than that of the Blue Nile – Lake Victoria was not definitively established as the major source of the White Nile until 260 years after Gish Abay was identified as the Blue Nile's source.^[124] In 1857, John Hanning Speke and Richard Francis Burton started a search for the Nile's source by departing from Zanzibar on the east coast of Africa – rather than traveling upriver from Egypt – and headed westward to the interior of Africa. They reached Lake Tanganyika and determined it was not the source.^[119][as] Speke returned to Africa in 1860 and traveled to Lake Victoria where he found a river flowing out from the north side of the lake, which he concluded was the Nile. However, he did not follow that river from Lake Victoria to Sudan, leading some to doubt his conclusion that the lake's outflow was the Nile.^[119][at]

In 1864, Samuel Baker became the first European to follow the Nile upstream from the Mediterranean Sea to Lake Albert.^[126][au] In 1874, Henry Morton Stanley circumnavigated Lake Victoria, and determined that the outflowing river that Speke had identified was the only river leaving the lake. That fact – in conjunction with the research from Baker and others – confirmed that Lake Victoria was the source of the Nile.^[127]

Efforts to pinpoint the furthermost source of the White Nile began in early 20th century when Richard Kandt suggested that the source was a tributary of the Kagera River in the Nyungwe Forest – the Kagera feeds into Lake Victoria.^[20] The source location was refined in 1969 when a group of researchers from Waseda University identified a specific tributary of the Kagera.^[20] In 2006, a group of adventurers rediscovered the 1969 location, and placed a large marker on a nearby tree.^[20] In 2009, academics used satellite imagery to further refine the location of the source, placing it at a spring several km from the 1969/2006 source.^[2][a]

Modern era and water politics

Post-colonial era

Egypt and Sudan became completely independent from Britain in 1956.^[136][aw] In 1959 Egypt and Sudan updated the 1929 water sharing agreement. The new agreement allocated the water be shared between Egypt and Sudan and at 55.5 and 18.5 billion cubic meters respectively.^[138] Upstream countries within the Nile Basin were excluded from the 1959 agreement – including Ethiopia, which is the source of over two thirds of the Nile's water.^[15]

The 1959 agreement included terms permitting Egypt and Sudan to build dams, which they did: Egypt built the Aswan High Dam (completed 1970); Sudan built the Khashm el-Girba Dam (1964), Roseires Dam (1966), Merowe Dam (2009), and Upper Atbara and Setit Dam Complex complex (2017).^[15][az]

In 1960, Egypt started building the Aswan High Dam (completed in 1970) which stores roughly two years flow of the Nile river.^[140] The dam effectively turned the downstream stretch of the Nile (from the dam to the sea) into a large irrigation canal.^[141] The dam had positive impacts (irrigation, electricity, and manufacturing) and negative impacts (water quality, siltation, schistosomiasis, and displacement of Nubians).^[142]

The Aswan High Dam flooded a large area of the Nile valley, and would have submerged several important historical monuments. An international campaign to save some monuments from becoming submerged by the new reservoir successfully saved some monuments, including the Abu Simbel temples.^[143] The Aswan High Dam also forced the relocation of many Nubians that lived in the valley innundated by the new reservoir. The Nubians were removed from their ancestral homelands, and many forced to immigrate to cities in Egypt and Sudan.^[144]

Late 20th century disagreements and negotiations

The gradient of the Nile is generally steeper in the upstream regions (left, in this graph), providing more opportunities for hydropower generation.^[145]

Throughout the 20th century, there was a marked imbalance in political power within the Nile Basin: Egypt and Sudan in the north wielded more power than other ten nations to the south.^[146] After Egypt and Sudan created the 1959 agreement, several of the upstream nations (including Kenya, Tanzania, Uganda, and Ethiopia) began to voice objections to the terms of the agreement, and argued that they were not bound by the agreement because they were not parties to it.^[147] The arguments of the upstream nations were that the dams built by Egypt and Sudan protected those two countries from drought, famine, and floods, yet upstream countries such as Ethiopia and were still subject to droughts and famine.^[148][ba] For example, the Aswan High Dam generated about 10 billion kilowatt hours per year; and enabled Egyptian farmers to cultivate three harvests per year, compared to a single harvest before the dam.^[150] Egyptian leaders often stated that they were willing to employ military force to protect their rights under the 1959 agreement.^[151]

In the late 20th century, African nations participated in several efforts to establish water-sharing policies – including the Undugu Commission (active from 1983 to 1993) and TECCONILE (active 1993 to 1998) – but were not successful in creating long-term agreements.^[152] In 1999, nine of the ten^[bb] Nile Basin countries – Burundi, Democratic Republic of the Congo, Egypt, Ethiopia, Kenya, Rwanda, Sudan, Tanzania and Uganda – established the Nile Basin Initiative to promote peaceful dialog regarding issues related to the Nile Basin.^[154]

Power shift to upstream nations

Further information: Grand Ethiopian Renaissance Dam

Since the colonial era, two downstream nations – Egypt and Sudan – exerted control over the Nile's waters from a position of dominance; but at the start of the 21st century, power shifted to the upstream nations.^[146] In 2008, Ethiopia built the Tekezé Dam without seeking permission of Egypt or Sudan.^[156] In 2010, five upstream countries – Uganda, Ethiopia, Rwanda, Tanzania, and Kenya^[bc] – signed a new agreement – the Cooperative Framework Agreement – which moved towards allocating Nile waters in a manner that benefited upstream countries. Kenya was motivated to sign the agreement because it had plans to pump water out of Lake Victoria for irrigation. The 2010 agreement was opposed by Egypt and Sudan.^[158] In 2011, South Sudan Became independent from Sudan, becoming the eleventh country in the Nile Basin. In subsequent water disputes, South Sudan allied with the upstream nations rather than with Sudan.^[27]

In 2011, Ethiopia announced plans to build a large dam on the Blue Nile near the border with Sudan. The dam was later named the Grand Ethiopian Renaissance Dam (GERD).^[159] Ethiopia viewed the GERD as essential to the nation's future, because the electrical power generated by the dam would enable them to significantly increase the quality of life of their populace. Egypt was concerned that the dam will imperil the irrigation of their crops because Egypt already uses far more water than enters the country, and they are concerned that the dam would exacerbate that shortfall. Sudan was concerned about safety and water supply.^[160] After the dam was announced, Egyptian president Mohamed Morsi hinted that military strikes on Ethiopia were an option,^[159] and Sudan and Egypt conducted several joint military exercises.^[161]

Numerous negotiations and mediations were conducted between Ethiopia, Sudan, and Egypt while the dam was constructed and the reservoir was filled.^[162] In 2015 the countries signed the "Declaration of Principles" which contained high-level agreements regarding water usage and reservoir filling procesures.^[163][bd] In 2019, the United States hosted talks between the involved nations.^[163] In 2020, the African Union started facilitating talks.^[164] In 2020, Egypt asked the United Nations Security Council to intervene, but it declined to do so.^[165] In 2021 and 2022, the UAE hosted talks.^[166] Construction of the GERD dam was completed in 2020, and in 2025 the reservoir was full and most of the dam's generators were producing electricity.^[167]

Agriculture

There is a significant difference in agricultural practices between the northern nations of the Nile Basin (Egypt, Sudan, and South Sudan) and the southern nations (Uganda, Ethiopia, etc).^[169] The north is primarily a desert, yet the south receives significant rainfall; crops in the north rely primarily on irrigation, whereas the south relies on rainfall retained in the soil; crop yields are higher in the north (due to intensive use of fertilizers and pesticides) than in the south; and the north has extensive irrigation infrastructure (dams, canals, etc) supported by governmental polices and international funding sources.^[169]

Crop yields in the south are adversely influenced by longer distances to market; in contrast to the north, where nearly all farms are concentrated along a narrow strip along river banks with ample transportation opportunities.^[170] The southern nations have few irrigation canals, instead relying on extensive rainfall: the amount of soil water used annually for crops in the south is 229 km³, which is more than twice the total annual water flow of the Nile River (about 100 km³).^[171]

The lack of rainfall and groundwater leads Egypt to rely on the Nile for virtually all its water needs.^[172] Principal crops grown in Egypt include cotton, wheat, corn, rice, sorghum, and fava beans.^[172] There are generally two growing seasons in Egypt: summer (cotton) and winter (grains and vegetables).^[173] Since the 1950s, Egypt has increasingly used industrial farming techniques (including extensive use of fertilizers and pesticides) to improve crop yield.^[174] Egypt's land is 94% desert and 3% arable land.^[173] The vast majority of Egypt's farmland is located in the Nile delta, with the remainder along the banks of the Nile.^[175]

The primary crops in Sudan are peanuts, cotton, sesame, sugarcane, and sorghum. Other crops include millet, wheat, corn, and barley.^[176] Sudan's crops draw upon water from both the Blue Nile and White Nile, supported by several dams including the Sennar dam and Khashm Al-Qirbah Dam.^[176] Much of the irrigated land is within the Gezira Scheme, an extensive irrigation project initiated in the 1920s.^[177]

Fisheries

The Nile river and its associated lakes have been an important food source for peoples living near the waters since prehistoric times.^[178] The Nile Basin supports several important fisheries and accounts for the majority of inland (fresh water) fish caught in the African continent. Data collected around the year 2000 shows that the Nile Basin produced about 1.4 million tonnes of fish per year, which is more than half of the total fresh water yield from the entire African continent (2.2 million tonnes).^[179] Lake Victoria alone – Africa's largest lake – provided 1 million tonnes.^[180] The yield of the lakes of the Nile Basin lake far exceed the amount of fish caught its rivers.^[178]

In the 1950s, Nile Perch and Nile Tilapia were introduced into Lake Victoria in an effort to reverse the shrinking yields of native fishes in the lake; the effort was successful, but led to a decline in number of native fish species in the lake.^[181] Currently, the vast majority of fish caught in Lake Victoria are Nile Perch and Silver cyprinid (Lake Victoria sardine).^[178] Some fisheries – particularly the Nile Perch – are primarily exported to Europe, rather than consumed locally.^[133] Fish farming is performed at some places in the basin.^[133][182]

All waters of the Nile basin – with the exception of the Sudd – show evidence of overfishing.^[183]

Hydropower

The Nile river and its tributaries power dozens of hydropower stations, which collectively have a capacity to generate over 10 gigawatts (GW) of electrical power.^[be] Prior to the year 2000, there were few dams on the Nile river, but thereafter governments accelerated the pace of dam construction.^[184][bf] Hydropower stations with capacities over 100 MW are listed in the table below.^[185][bg]

Transportation

In Ancient Egypt, the river was the primary route for transportation, and a wide variety of boats were built – both utilitarian and ceremonial.^[111] During the modern era, the river is still used for transportation, particularly in Egypt, which has four navigable waterways suitable for large ships: two in the delta, one between the delta and the Aswan High Dam, and one in Lake Nasser. Egypt moves 500 million tonnes of cargo on the river per year, which is only about 0.8% of Egypt's total cargo movement (the vast majority of cargo moves by road and railroad).^[bi] Cargo transported on the river includes cement, rock, coal, petroleum products, and phosphates.^[197]

Upstream from Lake Nasser, the Nile and its tributaries contain a large number of waterfalls, cataracts, rapids, and dams that make long-distance navigation difficult.^[198] Another obstacle to navigation is the Sudd, a large swampy wetland on the White Nile in South Sudan. Plans to build a canal through the swamp – called the Jonglei Canal – were initiated in the early 20th century; and construction was briefly started in 1978, but the endeavor was soon halted.^[199]

The Nile has a flatter gradient in the north relative to the mountainous southern region – so the northern countries (Egypt, Sudan, and South Sudan) have more navigable stretches of water.^[145] In Egypt, the river has no major obstacles between the delta and the first cataract at Aswan, and that stretch has historically been used for extensively for transportation.^[200] That stretch could be used even before the arrival of steamships, because currents could carry boats downstream, and winds from the north often helped sailboats travel upstream.^[200] The Blue Nile is generally not navigable in most places. Instead of the river, Ethiopians and Italian colonizers used an overland route – the Strada Imperiale – for north-south transportation in Ethiopia.^[201] As recently as 1903, explorers were still researching the Blue Nile to see if it could be used for transportation between Ethiopia and Sudan, but were not successful.^[202]

Tourism and recreation

The Nile river – in particular, the stretch in Egypt – has been one of the worlds most popular tourist destinations for millennia, and has been the source of vast amounts of travel literature.^[203][bj] Perhaps the most visited tourist destination along the Nile is the Giza pyramid complex – about 9 km from the modern course of the Nile in Cairo – which has been a tourist destination since the time of the Greeks.^[204]

The stretch of the Nile between Cairo and Aswan has long been a popular destination for tourists: during celebrations surrounding the opening of the Suez Canal in 1870, a large group of tourists took a boat ride on that stretch of the river and visited Luxor, Dendera, Saqqara, Edfu, and Philae.^[203] One of the worlds first travel agencies, Thomas Cook & Son, started offering tours of the river in 1870 when the Suez Canal opened, and started regular steamboat cruises on the Nile in 1875.^[205] Since the construction of the Aswan High Dam in 1970, the dam itself has become tourist attraction, along with the nearby temples that were moved during construction to avoid becoming submerged.^[206] The Aswan High Dam also benefited the cruise industry because the river from Aswan to the delta became safely navigable all year.^[207]

The Nile Basin is home to several parks and nature reserves, including Uganda's Murchison Falls National Park, Ziwa Rhino Sanctuary, Rwenzori Mountains National Park, and Queen Elizabeth National Park. South Sudan has the Boma National Park, Bandingilo National Park, Shambe National Park, and Zeraf Game Reserve. Sudan contains the Sabaloka Game Reserve. The Bandingilo National Park, near the White Nile, is in South Sudan. Egypt has Wadi al Hitan, Lake Burullus Protected Area, Wadi Allaqi biosphere, and Salouga and Ghazal Protected Area.

The river has several major cities on or near its banks including Cairo, Khartoum, Juba, and Kampala. These cities have hotels and facilities for tourists, such as the Speke Resort and Conference Center, opened in Kampala in 2007.^[208] The Bujagali Falls were once one of Africa's most notable rafting sites, but have become submerged due to construction of the Bujagali Power Station.^[209]

Art and literature

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.^[212]

Landscape artwork featuring the Nile river – either directly or allegorically – are called Nilotic landscapes. The term primarily designates artwork from ancient Greek or ancient Rome, though it is occasionally used to refer to scenes of hunting and fishing in Egyptian art. Nilotic landscapes are characterized by a river scene with rich and abundant plant and animal life, much of which is native to Egypt. Common iconographic elements include papyrus, palm trees, fish and water birds, and in some cases felines, monkeys, and/or crocodile. Imperial Roman scenes have a larger emphasis on fierce animals, usually including crocodiles and hippopotamus.^[210]

A notable representation of the Nile in art is the Personification of the River Nile, a colossal marble sculpture from c. 2nd century AD Rome – now in the Vatican Museum.^[bk] The Nile is represented as a reclining man holding sheaves of wheat in his hand. At his side are a sphinx – representing Egypt – and sixteen children which allude to sixteen cubits (the ideal height of the annual flood). At the base are crocodiles, pygmies, and hippopotamus.^[211]

The Nile is seen in artworks that feature four major rivers of the world: Nile (Africa), Danube (Europe), Ganges (Asia), and Río de la Plata (Americas). Examples include the painting The Four Rivers of Paradise by Peter Paul Rubens (1615),^[214] and the fountain in Rome Fontana dei Quattro Fiumi designed by Gian Lorenzo Bernini (1651).^[215] In Bernini's fountain, the Nile is depicted as a man with his head coverd in a cloth, symbolizing the mystery of the unknown source of the Nile.^[216]

Shakespeare has the character Marc Antony describe the Nile floods in the play Antony and Cleopatra: "Thus do they, sir: they take the flow o’ the Nile By certain scales i’ the pyramid; they know, By the height, the lowness, or the mean, if dearth Or foison follow: the higher Nilus swells, The more it promises: as it ebbs, the seedsman Upon the slime and ooze scatters his grain, And shortly comes to harvest."^[217]

Myth and religion

The cosmology of the ancient Egyptians was cyclic in nature: rather than viewing life as having a start and end, it was viewed as a perpetual cycle. This cyclic life-view was rooted in nature that surrounded the Egyptians, the daily passage of the sun and the annual floods of the Nile.^[220] The Nile river served as an important dividing line between the living world and the netherworld: the east side was for the living, and the west side was for the dead.^[221][bl] The Nile was such a dominant source of water for the Egyptians, that they sometimes referred to rain as 'Nile in the sky'.^[222]

In the ancient Egyptian religion, no single god personified the Nile in the same way that the god Ra personified the sun.^[223] Gods associated with the river included Hapy (god of the annual floods) and Khnum (god of the first cataract), who were jointly responsible for producing the annual Nile flood that fertilized the country's farmland.^[218] The Egyptian religion placed the source of the Nile's annual flood at Elephantine Island (at the first cataract) where the floodwaters were believed to flow up out of the netherworld.^[224]

Isis was a major diety in the Egyptian religion who was strongly associated with the Nile river. Cults based on Isis spread from Egypt into Europe in the second century BC.^[225] An example of the influence of the cult of Isis in Europe is the Nile mosaic of Palestrina, located in Rome and dated to first century BC: the 4 by 3 meter mosaic depicts a detailed Nilotic landscape.^[120]

In Greek mythology, Nilus is the god of the Nile river, one of thousands of river-god children of Titans Oceanus and his sister-wife Tethys. Nilus was father of the naiad Memphis, mythical founder of the city of Memphis.^[226]

The Nile river is mentioned in the Bible dozens of times, including a story in the Book of Exodus about the infant Moses being placed in a basket in the river.^[219] Some authorities identify the river Gihon – which is mentioned in the Book of Genesis as one of the four Rivers of Paradise  – as the Nile river.^[219] A story particularly important to the Coptic peoples of Egypt is found in the Book of Matthew: it recounts how Joseph and Mary fled to Egypt and lived near the Nile for several years, thus avoiding Herod.^[219]

Footnotes

Citations