Editing Nile (section)

== Tributaries ==

=== Atbarah River ===
{{main|Atbarah River}}
Below 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 {{convert|800|km|sigfig=1|sp=us}} 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]].

=== Blue Nile ===
{{main|Blue Nile}}
[[File:ET Bahir Dar asv2018-02 img17 Tis Issat.jpg|thumb|left|The [[Blue Nile Falls]] fed by [[Lake Tana]] near the city of [[Bahir Dar]], Ethiopia]]
[[File:ISS036-E-011050.jpg|thumb|Annotated view of the Nile and Red Sea, with a dust storm<ref>{{Cite web |url=https://earthobservatory.nasa.gov/images/81566/egyptian-dust-plume-red-sea |archive-url=https://web.archive.org/web/20140222100350/http://earthobservatory.nasa.gov/IOTD/view.php?id=81566 |url-status=dead |title=Egyptian Dust Plume, Red Sea |date=8 July 2013 |archive-date=22 February 2014 |website=earthobservatory.nasa.gov }}</ref>]]
The Blue Nile ({{langx|am|ዓባይ}}, ''ʿĀbay''<ref>[[United States Board on Geographic Names|BGN]]/[[Permanent Committee on Geographical Names for British Official Use|PCGN]]. "[http://earth-info.nga.mil/gns/html/romanization.html Romanization System for Amharic] {{webarchive |url=https://web.archive.org/web/20130213212545/http://earth-info.nga.mil/gns/html/romanization.html |date=13 February 2013 }}". 1967. Hosted at the [[National Geospatial-Intelligence Agency]], 2013. Accessed 28 February 2014.</ref><ref>See also: [[BGN/PCGN romanization|{{sc|BGN/PCGN}} romanization]].</ref>) springs from Lake Tana in 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.<ref>{{Cite encyclopedia |title=Blue Nile River {{!}} river, Africa |encyclopedia=Encyclopedia Britannica |url=https://www.britannica.com/place/Blue-Nile-River |access-date=31 July 2017 |archive-url=https://web.archive.org/web/20170801185437/https://www.britannica.com/place/Blue-Nile-River |archive-date=1 August 2017 |url-status=live }}</ref> Ninety percent of the water and ninety-six percent of the transported sediment carried by the Nile<ref>Marshall et al.,{{Cite web |title=Late Pleistocene and Holocene environmental and climatic change from Lake Tana, source of the Blue Nile |url=http://www.holivar2006.org/abstracts/pdf/T1-026.pdf |url-status=dead |archive-url=https://web.archive.org/web/20060928124412/http://www.holivar2006.org/abstracts/pdf/T1-026.pdf |archive-date=28 September 2006 |access-date=30 September 2006 }}</ref> come from the Atbarah and Blue Nile,{{fix|text=1,922 out of 2,633 m3/s = 73%, so somewhere our numbers are off}} 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 the Ethiopian [[Wet season|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.<ref>{{Cite web |date=26 April 2013 |title=Two Niles Meet : Image of the Day |url=https://earthobservatory.nasa.gov/IOTD/view.php?id=81186 |url-status=live |archive-url=https://web.archive.org/web/20170415093951/https://earthobservatory.nasa.gov/IOTD/view.php?id=81186 |archive-date=15 April 2017 |access-date=31 July 2017 |website=earthobservatory.nasa.gov }}</ref>

The flow of the Blue Nile varies considerably over its yearly cycle and is the main contribution to the large natural variation of the Nile flow. During the dry season the natural discharge of the Blue Nile can be as low as {{cvt|113|m3/s|sp=us}}, although upstream dams regulate the flow of the river. During the wet season, the peak flow of the Blue Nile often exceeds {{cvt|5663|m3/s|sp=us}} in late August (a difference of a factor of 50).

Before the placement of dams on the river the yearly discharge varied by a factor of 15 at Aswan. Peak flows of over {{cvt|8212|m3/s|sp=us}} occurred during late August and early September, and minimum flows of about {{cvt|552|m3/s|sp=us}} occurred during late April and early May.

=== Bahr el Ghazal and Sobat River ===
The [[Bahr el Ghazal River|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 is the largest of any of the Nile's sub-basins, measuring {{convert|520000|km2|sigfig=2|sp=us}} in size, but it contributes a relatively small amount of water, about {{cvt|2|m3/s|sp=us}} 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, {{cvt|225000|km2|sigfig=3|sp=us}}, but contributes {{convert|412|m3/s|sigfig=3|sp=us}} annually to the Nile.<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=276, 287–288 |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> When in flood the Sobat carries a large amount of sediment, adding greatly to the White Nile's color.<ref>{{Cite encyclopedia |title=Sobat River |encyclopedia=Encyclopædia Britannica Online Library Edition |publisher=[[Encyclopædia Britannica]] |url=http://www.library.eb.com/eb/article-9068426 |access-date=21 January 2008 }}</ref>

=== Yellow Nile ===
[[File:Nile Map Sudan.png|thumb|280px|Map of Nile tributaries in modern Sudan, showing the Yellow Nile]]
[[File:Scena nilotica from casa del fauno.jpg|thumb|280px|The Nile represented in an ancient Roman mosaic found from the ruins of [[Pompeii]].]]

The Yellow Nile is a former tributary that connected the [[Ouaddaï highlands]] of eastern Chad to the Nile River Valley {{circa|8000}} to {{circa|1000 BCE}}.<ref>{{cite book |last=Keding |first=B. |year=2000 |chapter=New data on the Holocene occupation of the Wadi Howar region (Eastern Sahara/Sudan) |title=Recent research into the Stone Age of Northeastern Africa |editor-first=L. |editor-last=Krzyzaniak |editor2-first=K. |editor2-last=Kroeper |editor3-first=M. |editor3-last=Kobusiewicz |series=Studies in African Archaeology |volume=7 |location=Poznań |publisher=Poznań Archaeological Museum |pages=89–104 |isbn=83-907529-6-4 }}</ref> Its remains are known as the [[Wadi Howar]]. The wadi passes through [[Gharb Darfur]] near the northern border with Chad and meets up with the Nile near the southern point of the Great Bend.