Editing Nile (section)

== History ==
{{further|Sahara#Climate history}}

[[File:Herodotus world map-en.svg|thumb|Reconstruction of the [[Oikoumene]] (inhabited world), an ancient map based on [[Herodotus]]' description of the world, {{circa|450 BC}}]]
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]].<ref>{{Cite journal |last1=Carmignani, Luigi |last2=Salvini, Riccardo |last3=Bonciani, Filippo |year=2009 |title=Did the Nile River flow to the Gulf of Sirt during the late Miocene? |url=https://www.researchgate.net/publication/256483636 |journal=Bollettino della Societa Geologica Italiana (Italian Journal of Geoscience) |volume=128 |issue=2 |pages=403–408 |doi=10.3301/IJG.2009.128.2.403 |doi-broken-date=1 November 2024 }}</ref> As the sea level rose at the end of the [[Last Glacial Period|most recent ice age]], the stream which is now the northern Nile [[Stream capture|captured]] the ancestral Nile near [[Asyut]].<ref>{{Cite journal |last1=Salvini, Riccardo |last2=Carmignani, Luigi |last3=Francionib, Mirko |last4=Casazzaa, Paolo |year=2015 |title=Elevation modelling and palaeo-environmental interpretation in the Siwa area (Egypt): Application of SAR interferometry and radargrammetry to COSMO-SkyMed imagery |journal=Catena |volume=129 |pages=46–62 |doi=10.1016/j.catena.2015.02.017 |bibcode=2015Caten.129...46S |hdl-access=free |hdl=10871/20327 }}</ref> This change in climate also led to the current extents of the [[Sahara]] desert, around 3400 BCE.<ref>Although the ancestral Sahara Desert initially developed at least 7 million years ago, it grew during interglacial periods and shrank during glacial ones. The growth of the current Sahara began about 6,000 [[Before Present|years ago]]. {{Cite journal |last=Schuster, Mathieu |display-authors=etal |year=2006 |title=The age of the Sahara desert |url=https://www.researchgate.net/publication/51372753 |journal=Science |volume=311 |issue=5762 |pages=821 |doi=10.1126/science.1120161 |pmid=16469920 |s2cid=206508108 }}</ref>

=== Khufu branch ===

The [[Giza pyramid complex]] originally overlooked a branch of the Nile that no longer exists. This branch was highest during the [[African Humid Period]].<ref>{{Cite journal |last=Sheisha, Hader |year=2022 |title=Nile waterscapes facilitated the construction of the Giza pyramids during the 3rd millennium BCE |journal=PNAS |volume=119 |issue=37 |pages=e2202530119 |doi=10.1073/pnas.2202530119 |doi-access=free |pmid=36037388 |pmc=9477388 |bibcode=2022PNAS..11902530S }}</ref><ref name="Solis-Moreira 2022">{{cite web |last=Solis-Moreira |first=Jocelyn |title=A dried-up arm of the Nile provides another clue to how Egyptians built the pyramids |website=Popular Science |date=31 August 2022 |url=https://www.popsci.com/environment/ancient-egypt-pyramids-construction-khufu-branch/ |access-date=2 September 2022 }}</ref>

=== Ancient Niles ===
The existing Nile has five earlier phases:
*i) the Upper Miocenian Eonile, of about 6 million years [[Before Present|BP]];<ref name="Rushdi Said">{{Cite book |last=Said |first=Rushdi |url=https://books.google.com/books?id=ekjgBAAAQBAJ&q=Nile |title=The River Nile Geology, Hydrology and Utilization |date=22 October 2013 |publisher=Elsevier Science |isbn=9781483287683 |edition=22 October 2013 |publication-date=1993 |page=1 |format=Ebook |author-link=Rushdi Said |access-date=23 May 2021 |archive-date=30 May 2023 |archive-url=https://web.archive.org/web/20230530130718/https://books.google.com/books?id=ekjgBAAAQBAJ&q=Nile |url-status=live }}</ref><ref name="Said 3 x 3" />
*ii) the Upper Pliocenian Paleonile, commencing about 3.32 million years BP, and during the [[Pleistocene]];
*iii) The Nile phases, including the Proto-Nile, commencing about 600,000 years BP;
*iv) Pre-Nile;<ref name="Said/chapter/10.1007"/>
*v) transitioning at about 400,000 years BP to the Neo-Nile.<ref name="Rushdi Said" /><ref name="Said/chapter/10.1007">{{Cite book |last=Said |first=R |title=The Nile, Biology of an Ancient River |publisher=Springer |year=1976 |isbn=978-94-010-1563-9 |editor-last=Rzóska |editor-first=J. |series=Monographiae Biologicae |volume=29 |location=Dordrecht |publication-date=1976 |page=2 |chapter=The Geological Evolution of the River Nile in Egypt |doi=10.1007/978-94-010-1563-9_1 |access-date=23 May 2021 |chapter-url=https://link.springer.com/chapter/10.1007%2F978-94-010-1563-9_1 |archive-url=https://archive.today/20210523173149/https://link.springer.com/chapter/10.1007/978-94-010-1563-9_1%23citeas |archive-date=23 May 2021 |via=[[Microsoft Academic]] }}</ref>
Flowing north from 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&nbsp;million years before present. The Eonile transported [[Clastic rock|clastic sediments]] to the Mediterranean; several natural gas fields have been discovered within these sediments.

During the late-[[Miocene]] [[Messinian salinity crisis]], when the Mediterranean Sea was a [[Endorheic basin|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 {{cvt|2400|m|sp=us|sigfig=2}} below Cairo.<ref name="Warren2006">{{Cite book |last=Warren |first=John |url=https://archive.org/details/evaporitessedime0000warr |title=Evaporites: Sediments, Resources and Hydrocarbons |publisher=Springer |year=2006 |isbn=3-540-26011-0 |location=Berlin |page=[https://archive.org/details/evaporitessedime0000warr/page/352 352] |url-access=registration }}</ref><ref name="Mahmoudi2008">{{Cite journal |last1=El Mahmoudi |first1=A. |last2=Gabr |first2=A. |year=2008 |title=Geophysical surveys to investigate the relation between the Quaternary Nile channels and the Messinian Nile canyon at East Nile Delta, Egypt |journal=Arabian Journal of Geosciences |volume=2 |issue=1 |pages=53–67 |doi=10.1007/s12517-008-0018-9 |issn=1866-7511 |s2cid=128432827 }}</ref> This created a very long and deep canyon which was filled with sediment after the Mediterranean was recreated.<ref name="Embabi2018">{{Cite book |last=Embabi |first=N.S. |title=Landscapes and Landforms of Egypt |year=2018 |isbn=978-3-319-65659-5 |series=World Geomorphological Landscapes |pages=39–45 |chapter=Remarkable Events in the Life of the River Nile |doi=10.1007/978-3-319-65661-8_4 |issn=1866-7538 |chapter-url=https://link.springer.com/book/10.1007/978-3-319-65661-8 |access-date=4 February 2020 |archive-date=4 February 2020 |archive-url=https://web.archive.org/web/20200204215026/https://link.springer.com/book/10.1007/978-3-319-65661-8 |url-status=live }}</ref> At some point the sediments raised 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 Mountains|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.<ref name="Said 3 x 3" />

[[Affad 23]] 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.<ref name="Osypiński">{{cite journal |last1=Osypiński |first1=Piotr |last2=Osypińska |first2=Marta |last3=Gautier |first3=Achilles |title=Affad 23, a Late Middle Palaeolithic Site With Refitted Lithics and Animal Remains in the Southern Dongola Reach, Sudan |journal=Journal of African Archaeology |date=2011 |volume=9 |issue=2 |pages=177–188 |doi=10.3213/2191-5784-10186 |url=https://www.jstor.org/stable/43135549 |issn=1612-1651 |oclc=7787802958 |jstor=43135549 |s2cid=161078189 |access-date=12 September 2023 |archive-date=1 August 2023 |archive-url=https://web.archive.org/web/20230801080857/https://www.jstor.org/stable/43135549 |url-status=live |url-access=subscription }}</ref>

=== Integrated Nile ===
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 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.<ref name="Said1981">Said, R. (1981). ''The geological evolution of the River Nile''. [[Springer Verlag]].</ref>

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.<ref name="WW1980">Williams, M.A.J.; Williams, F. (1980). ''Evolution of Nile Basin''. In M.A.J. Williams and H. Faure (eds). ''The Sahara and the Nile''. Balkema, Rotterdam, pp. 207–224.</ref>

R. B. Salama suggests that a series of separate closed continental basins each occupied one of the major parts of the Sudanese Rift System that during the [[Paleogene]] and [[Neogene]] periods (66&nbsp;million to 2.588&nbsp;million years ago): [[Melut Basin|Mellut rift]], [[White Nile rift]], [[Blue Nile rift]], [[Atbara rift]] and [[Sag El Naam rift]].<ref name="Salama1987">{{Cite journal |last=Salama, R.B. |year=1987 |title=The evolution of the River Nile, The buried saline rift lakes in Sudan |journal=Journal of African Earth Sciences |volume=6 |issue=6 |pages=899–913 |doi=10.1016/0899-5362(87)90049-2 }}</ref>
The Mellut Basin is nearly {{convert|12|km|mi|sp=us|sigfig=2}} deep at its central part. This rift could possibly be still active, with reported [[Tectonics|tectonic]] activity in its northern and southern boundaries. The [[Sudd]] swamp which forms 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 {{convert|9|km|mi|sp=us|sigfig=2}} deep. Geophysical exploration of the Blue Nile Rift System estimated the depth of the sediments to be {{convert|5|–|9|km|sp=us|sigfig=2}}. These basins were not interconnected until their subsidence ceased, and the rate of sediment deposition 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.<ref name="Salama1997">Salama, R.B. (1997). ''Rift Basins of Sudan. African Basins, Sedimentary Basins of the World. 3.'' Edited by R.C. Selley (Series Editor K.J. Hsu) pp. 105–149. ElSevier, Amsterdam.</ref> 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 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]].

=== Role in the founding of Egyptian civilization ===
{{See also|Ancient Egyptian agriculture}}
[[File:Vallee fertile du Nil a Louxor.jpg|thumb|An aerial view of [[irrigation]] from the Nile River supporting agriculture in [[Luxor|Luxor, Egypt]]]]
[[File:Dhows on the Nile.jpg|thumb|upright|right|A [[felucca]] traversing the Nile near Aswan]]
The Greek historian [[Herodotus]] wrote that "Egypt was the gift of the Nile". An unending source of sustenance, it played a crucial role in 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 Egypt]]ians 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 the Nile since ancient times.{{Citation needed|date=October 2022}} 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.<ref name=":3">{{Cite web |last=Halsall |first=Paul |date=May 1998 |title=Hymn To The Nile |url=http://sourcebooks.fordham.edu/ancient/hymn-nile.asp |access-date=20 November 2016 |website= |publisher=Fordham University }}</ref>

[[Water buffalo]] were introduced from Asia, and the [[Assyrian people|Assyrians]] introduced camels in the 7th century BCE. These animals were raised for meat and were domesticated and used for ploughing—or in 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 (Nile god)|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 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.{{citation needed|date=April 2022}}

As the Nile was such an important factor in Egyptian life, 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 [[Season of the Inundation|Akhet]], [[Season of the Emergence|Peret]], and [[Season of the Harvest|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.<ref name="SpringerMorris2010">{{Cite book |last1=Springer |first1=Lisa |title=Art and Culture of Ancient Egypt |last2=Neil Morris |publisher=The Rosen Publishing Group |year=2010 |isbn=978-1-4358-3589-4 |page=8 }}</ref> Peret was the growing season, and Shemu, the last season, was the harvest season when there were no rains.<ref name="SpringerMorris2010" />

=== European search for the source ===
[[File:JH Speke.jpg|thumb|upright|left|[[John Hanning Speke|John&nbsp;Hanning&nbsp;Speke]]&nbsp;{{circa|lk=no|1863}}. Speke was the [[Victorian Age|Victorian]] explorer who first reached [[Lake Victoria]] in 1858, returning to establish it as the source of the Nile by 1862.{{sfn|Garstin|Cana|1911|p=698}}]]

To the ancient Greeks and Romans, the upper reaches of the White Nile remained largely unknown, as they failed to penetrate the ''[[Sudd]]'' wetlands of South Sudan. [[Vitruvius]] thought that source of the Nile was in Mauritania, on the "other" (south) side of the [[Atlas Mountains]].<ref>Vitruvius, ''de Architectura'', VII.2.7.</ref> 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 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, the Middle East and Africa, and described being told of the source of the Nile in Abyssinia (Ethiopia).<ref name="THE TRAVELS OF JOHN DE MARIGNOLLI">{{Cite book |last=Yule |first=Henry |url=https://depts.washington.edu/silkroad/texts/marignolli.html |title=Sir Henry Yule, Cathay and the way thither: being a collection of medieval notices of China Vol. II (1913–16) |publisher=Hakluyt Society |location=London |pages=209–269 |access-date=18 December 2018 |archive-url=https://web.archive.org/web/20190122140845/http://depts.washington.edu/silkroad/texts/marignolli.html |archive-date=22 January 2019 |url-status=live }}</ref> 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 ({{circa|1452}}–1483), a Venetian traveller in Ethiopia, wrote a journal of his travels to the ''origin of the Nile'' that has since been lost.<ref>[https://books.google.com/books?id=hg5BAQAAMAAJ Dizionario biografico universale], Volume 5, by Felice Scifoni, Publisher Davide Passagli, Florence (1849); page 411.</ref><ref>[https://books.google.com/books?id=l3cvAQAAMAAJ Ten Centuries of European Progress] {{Webarchive|url=https://web.archive.org/web/20230530130716/https://books.google.com/books?id=l3cvAQAAMAAJ |date=30 May 2023 }} by Lowis D'Aguilar Jalkson (1893) pages 126–127.</ref>
[[James Bruce]] claimed to be the first European to have visited the headwaters.<ref>[[Travels to Discover the Source of the Nile]]</ref>
Modern writers give the credit to the [[Society of Jesus|Jesuit]] [[Pedro Páez]]. Páez's account of the source of the Nile<ref>''History of Ethiopia'', circa 1622</ref> is a long and vivid account of Ethiopia. It was published in full only in the early 20th century, but was featured in works of Páez's contemporaries, like Baltazar Téllez,<ref>''Historia geral da Ethiopia a Alta'', 1660</ref> [[Athanasius Kircher]]<ref>''Mundus Subterraneus'', 1664</ref> and [[Johann Michael Vansleb]].<ref>''The Present State of Egypt'', 1678.</ref>

Europeans had been resident in Ethiopia since 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 [[Blue Nile Falls|Tis Issat]] Falls in his 1565 memoirs, compared them to the Nile Falls alluded to in [[Cicero]]'s ''De Republica''.<ref>S. Whiteway, editor and translator, ''The Portuguese Expedition to Abyssinia in 1441–1543'', 1902. (Nendeln, Liechtenstein: Kraus Reprint, 1967), p. 241. Referring to [[Cicero]], ''De Republica'', [http://www.attalus.org/translate/republic6.html#19 6.19] {{Webarchive|url=https://web.archive.org/web/20210602214358/http://attalus.org/translate/republic6.html#19 |date=2 June 2021 }}.</ref> [[Jerónimo Lobo]] describes the source of the Blue Nile, visiting shortly after Pedro Páez. Telles also uses his account.

The White Nile 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 a distance of 20 days' journey till it reaches the nearest Ethiopians."<ref>''[[Natural History (Pliny)|Natural History]]'', [http://www.attalus.org/translate/pliny_hn5a.html#51 5.(10).51]</ref>

[[File:EB1911 Nile v2.png|left|thumb|upright|A map of the Nile {{circa|lk=no|1911}}, when its entire primary course ran through British occupations, condominiums, colonies, and protectorates{{sfn|Garstin|Cana|1911|p=693}}]]

Modern exploration of the Nile basin began with the [[Turco-Egyptian conquest of Sudan (1820–1824)|conquest of the northern and central Sudan]] by the [[Ottoman Empire|Ottoman]] viceroy of Egypt, [[Muhammad Ali 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 a Turkish officer, Selim Bimbashi, were made between 1839 and 1842, and two got to the point about {{convert|30|km|mi|-1|abbr=off}} 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 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 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 the lake's northern shore.

=== Since 1950 ===
[[File:KageraRuvubu.jpg|thumb|right|The confluence of the [[Kagera river|Kagera]] and [[Ruvubu river|Ruvubu]] rivers near [[Rusumo Falls]], part of the Nile's upper reaches]]
[[File:Nile03(js).jpg|thumb|[[Dhows]] on the Nile]] [[File:View from Cairo Tower 31march2007.jpg|thumb|The Nile passes through Cairo, Egypt's capital city.]]
The Nile has long been used to transport goods along its length. Winter winds blow south, up river, so ships could sail up river using sails and down river using the flow of the river. While most Egyptians still live in the Nile valley, the 1970 completion of the Aswan Dam ended the summer floods and their renewal of the fertile soil, fundamentally changing farming practices. The Nile supports much of the population living along its banks, enabling Egyptians to live in otherwise inhospitable regions of the Sahara. The river's flow is disturbed at several points by the Cataracts of the Nile which form an obstacle to navigation by boats. The Sudd also forms a formidable navigation obstacle and impedes water flow, to the extent that Sudan had once attempted to build the [[Jonglei Canal]] to bypass the swamp.<ref>{{Cite book |last=Shahin |first=Mamdouh |url=https://books.google.com/books?id=ZmdYFTlcSgEC |title=Hydrology and Water Resources of Africa |publisher=Springer |year=2002 |isbn=1-4020-0866-X |pages=286–287 |access-date=25 July 2015 |archive-url=https://web.archive.org/web/20150905222900/https://books.google.com/books?id=ZmdYFTlcSgEC |archive-date=5 September 2015 |url-status=live }}</ref><ref>[https://books.google.com/books?id=6CcDAAAAMBAJ&pg=PA34 "Big Canal To Change Course of Nile River"] {{Webarchive |url=https://web.archive.org/web/20150905230928/https://books.google.com/books?id=6CcDAAAAMBAJ&pg=PA34 |date=5 September 2015 }}. October 1933. ''[[Popular Science]]'' (short article on top-right of page with map).</ref>

Nile cities include Khartoum, Aswan, [[Luxor]] (Thebes), and the [[Giza]]{{spaced ndash}}Cairo [[conurbation]]. The first cataract, the closest to the mouth of the river, is at Aswan, north of the Aswan Dam. This part of the river is a regular tourist route, with cruise ships and traditional wooden sailing boats known as [[felucca]]s. Many cruise ships ply the route between Luxor and Aswan, stopping at [[Edfu]] and [[Kom Ombo]] along the way. Security concerns have limited cruising on the northernmost portion for many years.

A computer simulation study to plan the economic development of the Nile was directed by H.A.W. Morrice and W.N. Allan, for the Ministry of Hydro-power of Sudan, during 1955–57<ref>{{Cite journal |last1=Morrice |first1=H.A.W. |last2=Allan |first2=W N. |year=1959 |title=Planning for the ultimate hydraulic development of the Nile Valley |journal=Proceedings of the Institution of Civil Engineers |volume=14 |issue=2 |pages=101–156 |doi=10.1680/iicep.1959.11963 }}</ref><ref>{{Cite journal |last=Barnett |first=M.P. |year=1957 |title=Comment on the Nile Valley Calculations |journal=Journal of the Royal Statistical Society, Series B |volume=19 |page=223 |jstor=2983815 }}</ref><ref>D.F. Manzer and M.P. Barnett, ''Analysis by Simulation: Programming Techniques for a High-Speed Digital Computer'', in Arthur Maas ''et al.'', ''Design of Water Resource Systems'', pp. 324–390, [[Harvard University Press]], Cambridge, Massachusetts, 1962.</ref> Morrice was their hydrological adviser, and Allan his predecessor. The calculations were enabled by accurate monthly inflow data collected for 50 years. The underlying principle was the use of over-year storage, to conserve water from rainy years for use in dry years. Irrigation, navigation and other needs were considered. Each computer run postulated a set of reservoirs and operating equations for the release of water as a function of the month and the levels upstream. The behavior that would have resulted given the inflow data was modeled. Over 600 models were run. Recommendations were made to the Sudanese authorities. The calculations were run on an [[IBM 650]] computer. Simulation studies to design water resources are discussed further in the article on [[hydrology transport model]]s, which have been used since the 1980s to analyze water quality.

Despite the development of many reservoirs, drought during the 1980s led to widespread starvation in Ethiopia and Sudan, but Egypt was nourished by water impounded in Lake Nasser. Drought has proven to be a major cause of fatality in the Nile river basin. According to a report by the [[Strategic Foresight Group]], droughts in the last century have affected around 170 million people and killed half a million people.<ref name="Blue Peace for the Nile, 2009">[http://www.strategicforesight.com/publication_pdf/11374Nile%20concise.pdf Blue Peace for the Nile, 2009] {{webarchive |url=https://web.archive.org/web/20130908163426/http://www.strategicforesight.com/publication_pdf/11374Nile%20concise.pdf |date=8 September 2013 }}; Report by Strategic Foresight Group</ref> From the 70 incidents of drought which took place between 1900 and 2012, 55 incidents took place in Ethiopia, Sudan, South Sudan, Kenya and Tanzania.<ref name="Blue Peace for the Nile, 2009" />