Editing Sudd

{{short description|Swamp in South Sudan}}
{{Use dmy dates|date=January 2020}}
{{Infobox ecoregion
| name = Sudd
| image = Sudd swamp.jpg
| image_size = 
| image_alt = 
| image_caption = Sudd Swamp from space, May 1993. This photograph was taken during the driest time of the year.
| map = Sudd location map.svg
| map_size = 
| map_alt = 
| map_caption = Location of the Sudd in South Sudan
| biogeographic_realm = [[Afrotropical realm|Afrotropical]]
| biome = [[flooded grasslands and savannas]]
| border = [[East Sudanian savanna]]
| border1 = [[Northern Congolian forest–savanna mosaic]]
| border2 = [[Sahelian Acacia savanna]]
| area = 57000
| country = South Sudan
| habitat_loss = 
| habitat_loss_ref = 
| protected = 
| protected_ref =
| global200 = 
| climate =
| coordinates = {{WikidataCoord|display=it}}
| embedded = {{Infobox mapframe|wikidata=yes|zoom=6|marker=natural|coord={{WikidataCoord|display=i}}}}
{{Designation list
 | embed = yes
 | designation1 = Ramsar
 | designation1_date = 5 June 2006
 | designation1_number = 1622<ref>{{cite web |title=Sudd |website=[[Ramsar Convention|Ramsar]] Sites Information Service |url=https://rsis.ramsar.org/ris/1622 |access-date=25 April 2018}}</ref>}}
}}

[[File:Pantanal_Sudd,_Sudão_do_Sul.jpg|thumb|300px|right|Satellite image of the swamp around the time of the wet season]]

The '''Sudd''' ({{langx|ar|السد|as-Sudd}}, [[Nuer language|Nuer]]: Baki̱ec, [[Dinka language|Dinka]]: Toc) is a vast [[swamp]] in [[South Sudan]], formed by the [[White Nile]]'s ''[[Mountain Nile|Baḥr al-Jabal]]'' section. The [[Arabic language|Arabic]] word ''{{Transliteration|ar|sudd}}'' is derived from ''{{Transliteration|ar|sadd}}'' ({{lang|ar|[[wikt:سد|سد]]}}), meaning "barrier"<ref>{{cite book |last1=Gaudet |first1=John J. |last2=Falconer |first2=A. |title=Remote sensing for tropical freshwater bodies. The problem of floating islands on Lake Naivasha |publisher=Regional Remote Sensing Facility |location=Nairobi, Kenya |year=1983}}</ref> or "obstruction".<ref>The ''[[New Oxford American Dictionary]]'' (''NOAD''), 3rd edition.</ref> The term "the sudd" has come to refer to any large solid floating vegetation island or mat. The area which the swamp covers is one of the world's largest [[wetland]]s and the largest freshwater wetland in the [[Nile Basin]].

For many centuries the swamp, and especially its thicket of vegetation, proved an impenetrable barrier to navigation along the Nile. The [[ancient Egypt]]ians failed to penetrate the Sudd and reach the areas south of it.<ref name="Dumont2009">{{cite book |title=The Nile Origin, Environments, Limnology and Human Use |publisher=Springer Science + Business Media B.V |year=2009 |isbn=978-1-4020-9725-6 |editor=Dumont |editor-first=Henri J. |series=Monographiae Biologicae |volume=89 |pages=1–21 |chapter=A Description of the Nile Basin, and a Synopsis of Its History, Ecology, Biogeography, Hydrology, and Natural Resources}}</ref> In AD 61, [[Nero's exploration of the Nile|a party of Roman soldiers]] sent by the Emperor [[Nero]] proceeded up the White Nile but were not able to get beyond the Sudd, which marked the limit of Roman penetration into [[equatorial Africa]].<ref>{{cite journal |last=Kirwan |first=L.P. |author-link=L. P. Kirwan |title=Rome beyond The Southern Egyptian Frontier |url=https://www.jstor.org/stable/1790717 |journal=[[Geographical Journal]] |volume=123 |issue=1 |pages=13–19 |year=1957 |bibcode=1957GeogJ.123...13K |jstor=1790717 |doi=10.2307/1790717|url-access=subscription }}</ref> For the same reasons in later times, the [[Nile#European search for the source|search for the source of the Nile]] was particularly difficult; it eventually involved overland expeditions from the central African coast, so as to avoid having to travel through the Sudd.

In 2019, a study suggested that increased water flows into the Sudd may be partly causing up to a third of the whole [[West Africa]]n rise in [[atmospheric methane]] levels over the previous decade.<ref>{{cite journal |last1=Lunt |first1=Mark F. |last2=Palmer |first2=Paul I. |last3=Feng |first3=Liang |last4=Taylor |first4=Christopher M. |last5=Boesch |first5=Hartmut |last6=Parker |first6=Robert J. |title=An increase in methane emissions from tropical Africa between 2010 and 2016 inferred from satellite data |journal=[[Atmospheric Chemistry and Physics]] |volume=19 |pages=14721–14740 |issue=23 |year=2019 |display-authors=3 |s2cid=198448426 |bibcode=2019ACP....1914721L |hdl=20.500.11820/013be268-2ebf-478a-a9d0-1e80f8c4b888 |hdl-access=free |doi=10.5194/acp-19-14721-2019 |doi-access=free}}</ref><ref>{{cite web |title=Climate change: Methane pulse detected from South Sudan wetlands |url=https://www.bbc.co.uk/news/science-environment-50708544 |publisher=BBC News |date=2019}}</ref>

==Location==
The Sudd stretches from [[Mongalla, South Sudan|Mongalla]] to just outside the [[Sobat River]] [[confluence]] with the White Nile just upstream of [[Malakal]] as well as westwards along the [[Bahr el Ghazal River|Bahr el Ghazal]]. The shallow and flat [[River delta|inland delta]] lies between 5.5 and 9.5 degrees latitude north and covers an area of {{convert|500|km|mi}} south to north and {{convert|200|km|mi}} east to west between Mongalla in the south and Malakal in the north.

Its size is highly variable, averaging over {{convert|30000|km2|sqmi}}. During the [[wet season]] it may extend to over {{convert|130000|km2|sqmi}} comprising 21% of the country, depending on the inflowing waters, with the discharge from [[Lake Victoria]] being the main control factor of flood levels and area inundation. Since the Sudd area consists of various [[meander]]ing channels, [[lagoon]]s, reed and [[papyrus]] fields and loses half of its inflowing water through [[evapotranspiration]] in the permanent and seasonal floodplains, the complex hydrology has many primary and secondary effects.<ref>{{cite book |last=Sutcliffe |first=J.V. |author2=Parks, Y.P. |year=1999 |location=Wallingford, UK |title=IAHS Special Publication No. 5}}</ref> A major feature of the area is the incomplete [[Jonglei Canal]], which was planned to bypass waters from the Sudd to avoid evaporation losses and increase the amount of water discharged at the outlet of the Sudd.

From 1961 to 1963, a great increase in the flooded area occurred when the level of [[Lake Victoria]] rose, and the outflow increased. The total area of the Sudd is related to the amount of water reaching [[Bor, South Sudan|Bor]] from the [[White Nile#Albert Nile|Albert Nile]] and from torrents or seasonal watercourses that can add substantial amounts to the flow in the upstream end of the Sudd. During the 1960s increase in Lake Victoria discharge, where flows at Mongalla roughly doubled, the flows at Malakal at the northern end of the swamps increased by 1.5 times the previous average flow. As a consequence of these high flows, the areas of permanent swamp and seasonal floodplains have, taken together, increased to 2.5 times their former size. The swamps have increased the most, and the seasonal floodplain is 1.5 times its previous size.<ref name="mefit">{{cite book | last=Mefit-Babtie Srl |title=Development Studies of the Jonglei Canal Area, Range Ecology Survey, Final Report, Volume 2, Background |year=1983 | publisher=USAID PCE-I-00-96-00002-00 |location=Khartoum, Sudan}}</ref>

[[File:Судд.jpg|thumb|Settlement on Sudd flooded grassland]]

From the southern inflow of the [[White Nile#In South Sudan|Bahr al Jabal]] ("Sea of the Mountain") at Mongalla, the defined riverbed successively widens into a floodplain, where the waters flow in meandering river stretches and various channels and lagoons throughout the dry season. With rising water levels it expands over the semi-flooded grasslands during the flood season.

Slightly downstream of Bor, the [[Bahr el Zeraf]] ("Sea of the [[Giraffe]]s") river branches off the Bahr al Jabal to the east, diverting part of the flow, and again joins the Bahr al Jabal just before reaching Malakal. During the course of its flow, the Bahr al Jabal passes [[Lake No]], where the [[Bahr el Ghazal River|Bahr el Ghazal]] ("Sea of the [[Gazelle]]s") connects to the Bahr al Jabal, contributing an inflow with seasonal variation. At Malakal, the Sobat River joins into the system. The combined flows then stream to the north as the White Nile in a defined bed, joining with the Blue Nile waters at Khartoum to form the main Nile.

Sudd was designated as a [[Ramsar Convention|Ramsar Wetland of International Importance]] in 2006. An area of {{convert|57000|km2|sqmi}} was designated.

==Climate==
Hydrologically the Sudd plays an important role in storing floodwaters and trapping [[sediment]]s from the Bahr al Jabal. Roughly 55% of water entering the area is lost to evaporation.<ref name="baecher">{{cite book |last=Baecher |first=G. |title=The Nile Basin – Environmental transboundary opportunities and constraint analysis |year=2000 |publisher=USAID PCE-I-00-96-00002-00}}</ref> Water levels fluctuate by up to 1.5 metres, depending on the intensity of seasonal flooding.<ref name="mefit"/> The region receives less rainfall (typically between 55 and 65 centimetres per year) than neighbouring areas at the same latitude. [[Orographic lift]]ing on the eastern and western sides of the Sudd contribute to that condition.<ref>Zahran, A.B. 1986. Sudan Rainfall Variability – Towards a Drought Assessment Model. Interna. Confer. on water Resources Needs & Planning in Drought Prone Areas, 85–106</ref>

==Geomorphology==
The morphology of the area is defined by the channel and lagoon system of the permanent Sudd swamps, the adjacent flood plains, and the surrounding flat terrain. The Bahr al Jabal runs to the north-northwest and therefore in an angle to the gradient of the [[floodplain]], which slopes down to the north, while north of [[Juba]] the river flows in an incised trough. The banks of this trough decrease in height from south to north with the Bahr al Jabal approaching Bor and ending in the Sudd flood plain just north of Bor on the eastern bank and towards Shambe on the western bank. In the southern part, the river meanders from side to side in the restraining trough in one or more channels, but further north the swamp is not limited by higher ground and the system of river channels becomes increasingly complex. The characteristics of the river with its network of channels and lagoons are distinguishable in satellite imagery and digital elevation models.

The geology of the area is defined by heavy clay soils, highly [[Permeability (Earth sciences)|impermeable]] with a top layer of "black cotton" [[vertisol]] of approximately 500&nbsp;mm on average. Sandy soils are found only at depths of approximately {{convert|30|m|ft}} and below, as determined by well drilling profiles.<ref>Peterson, 2008</ref> This indicates a very limited groundwater influence on the area's hydrology.

==Population==
[[Nuer people|Nuer]] and [[Dinka people|Dinka]] pastoralists use the Sudd and the surrounding areas extensively. Livestock and rain-fed agriculture are the dominant means of support for the largely rural population for which the seasonal flooded grasslands along the Sudd provides valuable grazing lands.<ref name="baecher" />

==Vegetation and ecosystem==
Vegetation cover of the area can generally be classified in five categories which depend on the elevation of the area above river flood level: the lakes and rivers, the floating plant life of the swamp, river-flooded grasslands (Toic), rain-flooded grasslands, and wooded grasslands on the fringes. Grassland and woodland areas have been cultivated by local populations.

The density of the grasslands along the Sudd changes with the season, with tall grass in the rainy season and short dry grass in the dry season, when frequent fires also occur. The fluvial area is mostly overgrown with vegetation, with some main and side channels as well as lagoons of open water. The vegetation distribution is described in further detail in Sutcliffe (1974) and Petersen (2007). The main species are:

* ''[[Phragmites communis]]'' (shallow flooded, buried roots)
* ''[[Echinochloa pyramidalis]]'' (shallow flooded, buried roots)
* ''[[Oryza barthii]]'' (shallow flooded, buried roots)
* ''[[Echinochloa stagnina]]'' (deep flooded, superficial/floating roots)
* ''[[Vossia cuspidata]]'' (deep flooded, superficial/floating roots)
* ''[[Cyperus papyrus]]'' (deep flooded, superficial/floating roots)
* ''[[Typha domingensis]]''

The first three species are anchored so their distribution is limited to the depth of flooding. For the last species their root system needs to be permanently in water or saturated soil, which is a good indicator of flood patterns. ''P. communis'', ''E. pyramidalis'' and ''O. barthii'' for example dominate only in areas where the depth of flooding does not exceed 130&nbsp;cm over a period of ten years or 118&nbsp;cm for one month in the year.

Floating vegetation of ''C. papyrus'' had caused blockages in the Sudd swamps on a number of occasions between 1879 and 1900, when the plants were torn out by increased flooding. ''C. papyrus'' needs saturated conditions and can tolerate flooding that is not more than 150&nbsp;cm deep.<ref>{{cite journal |last=Sutcliffe |first=J.V. |title=A Hydrological Study of the Southern Sudd Region of the Upper Nile |journal=Hydrological Science Bulletin |volume=19 |issue=2 |year=1974 |pages=237–255 |doi=10.1080/02626667409493903}}</ref>

When the matted vegetation breaks free of its moorings, it forms floating islands of vegetation up to 30&nbsp;km in length. Such islands, in varying stages of decomposition, eventually break up.

Historically, the fully floating [[Pistia|Nile cabbage]] (''Pistia stratiotes'') was an important plant in the Sudd, but it has largely been replaced by the invasive [[Pontederia crassipes|water hyacinth]] (''Eichhornia crassipes'').<ref name=Green2009>{{cite book |author1=Green, J. |author2=A.I. El-Moghraby |chapter=Swamps of the Upper White Nile |pages=193–204 |editor=H.J. Dumont |title=The Nile |series=Monographiae Biologicae |publisher=Springer Science + Business Media B.V. |volume=89 |year=2009 |isbn=978-1-4020-9725-6}}</ref> The sluggish waters are host to a large population of [[mosquito]]es and [[parasite]]s that cause [[waterborne diseases]].

===Fauna===
Including several diverse aquatic habitats like swamps, lakes, channels and floodplains, the Sudd is rich in fish. Some 70 species have been recorded, and this mostly involves fish that are found in much of the Nile system such as [[marbled lungfish]], [[Polypterus senegalus|Senegal bichir]], [[African arowana]], ''[[Mormyrus caschive]]'', [[Nile carp]], [[Nile tilapia]], [[mango tilapia]], [[redbelly tilapia]], [[Nile perch]], ''[[Distichodus]] rostratus'', [[Hydrocynus forskahlii|elongate tigerfish]], [[Alestidae|African tetras]], [[Clarias gariepinus|African sharptooth catfish]], ''[[Synodontis frontosus]]'', ''[[Synodontis schall|S. schall]]'' and others.<ref name=Green2009/> Among the few [[Endemism|endemics]] of the Sudd system are ''[[Clarias]] engelseni'', ''[[Enteromius yeiensis]]'', ''[[Nothobranchius]] nubaensis'', ''N. virgatus'' and two apparently [[Undescribed taxon|undescribed species]] of ''[[Enteromius]]'', and the fish fauna in significant sections still has not been properly studied.<ref name=Neumann2016>{{cite journal |author1=Neumann, D. | author2=H. Obermaier |author3=T. Moritz |year=2016 |title=Annotated checklist for fishes of the Main Nile Basin in the Sudan and Egypt based on recent specimen records (2006–2015) |journal=Cybium |volume=40 |issue=4 |pages=287–317 |doi=10.26028/cybium/2016-404-004}}</ref>

Over 400 species of bird are found in the Sudd, including [[shoebill]]s (a stronghold for the species with several thousand individuals), [[great white pelican]]s, and [[black crowned crane]]s. The Sudd provides food and water to large populations of [[Bird migration|migrating birds]]. As the surrounding landscape is a large swath of dry [[Sahel]] across Africa, the swamp is also a haven for [[Animal migration|migrating]] mammals, especially [[antelope]]s, such as the [[bohor reedbuck]], [[sitatunga]] (the most aquatic antelope of the Sudd, mostly inhabiting permanent swampland), the endangered [[Nile lechwe]] (not in permanent swampland, but generally near the water's edge and often walking in shallow water), and the [[Kob|white-eared kob]] (further away from the permanent swampland).<ref name=Green2009/> White-eared kob, [[Tiang (antelope)|tiang]] and [[Mongalla gazelle]] take part in one of the largest mammal migrations on Earth, numbering about 1.2 million individuals in total.<ref>{{cite web |title=Massive Animal Herds Flourishing Despite Sudan War, Survey Reveals |publisher=[[National Geographic (magazine)|National Geographic]] |url=http://news.nationalgeographic.com/news/2007/06/070611-sudan-animals.html |archive-url=https://web.archive.org/web/20070614213924/http://news.nationalgeographic.com/news/2007/06/070611-sudan-animals.html |url-status=dead |archive-date =14 June 2007}} January 2007</ref><ref name=Furniss2010>Furniss, C. (2010) {{cite news |url=http://findarticles.com/p/articles/mi_hb3120/is_4_82/ai_n54800827/?tag=content;col1 |title=Draining Africa's Eden. |work=Geographical |year=2010}} Geographical, April 2010.</ref> The shallow water is frequented by [[Nile crocodile]]s and [[hippopotamus]]es. In more upland areas the Sudd was known as an historic habitat for the endangered [[African wild dog|painted hunting dog]], which however may have been exterminated in the region.<ref>C. Michael Hogan. 2009. [http://globaltwitcher.auderis.se/artspec_information.asp?thingid=35993 ''Painted Hunting Dog: Lycaon pictus'', GlobalTwitcher.com, ed. N. Stromberg] {{webarchive |url=https://web.archive.org/web/20101209234758/http://globaltwitcher.auderis.se/artspec_information.asp?thingid=35993 |date=9 December 2010}}</ref>

==Threats and preservation==
The long-running [[Second Sudanese Civil War|civil war in Southern Sudan]] seriously disrupted conservation efforts in the Sudd, especially as the widespread availability of weapons has encouraged wildlife poaching, including of elephants. There are three game reserves: [[Zeraf Island]] between the [[Zeraf River]] and the Nile, [[Shambe]] Reserve, and [[Mongalla Game Reserve]].

==Jonglei diversion canal==
{{main|Jonglei Canal}}
The early explorers searching for the [[Nile#European search for the source|source of the Nile]] experienced considerable difficulties, sometimes taking months to get through the Sudd.  In his 1972 book ''The White Nile'', [[Alan Moorehead]] says of the Sudd, "there is no more formidable swamp in the world".<ref>{{cite book |last=Moorehead |first=Alan |title=The White Nile |publisher=Book Club Associates |location=London |year=1972 |page=85}}</ref> The Sudd swamp is sustained by the water from the southwestern tributaries (the Bahr el Ghazal system) and consumes a proportion of the main river through evaporation and transpiration.

Sir William Garstin, Undersecretary of State of Public Works of Egypt, created the first detailed proposal for digging a canal east of the Sudd in 1907.<ref>{{cite web |title=The Egyptian Sudan, its history and monuments |url=https://archive.org/stream/egyptiansudanits02budg#page/484/mode/2up |work=archive.org |year=1907}}</ref> By bypassing the swamps, evaporation of the Nile's water would vastly decrease, allowing an increase in the area of cultivatable land in Egypt by {{convert|2000000|acres|km2|abbr=on|order=flip|comma=}}. The Egyptian government in the 1930s proposed digging a [[canal]] east of the Sudd to divert water from the Bahr al Jabal above the Sudd to a point farther down the White Nile, bypassing the swamps and carrying the White Nile's water directly to the main channel of the river.<ref>[https://books.google.com/books?id=6CcDAAAAMBAJ&dq=motor+gun+boat&pg=PA34 "Big Canal To Change Course of Nile River"], October 1933, ''[[Popular Science]]'', short article on top-right of page with map</ref>

The Jonglei Canal scheme was studied by the government of Egypt in 1946, and plans were developed between 1954 and 1959. Construction work on the canal began in 1978, but the outbreak of political instability in Sudan has held up work for many years. By 1984 when the [[Sudan People's Liberation Movement-North|Sudan People's Liberation Army]] brought the works to a halt, 240&nbsp;km of the canal of a total of 360&nbsp;km had been excavated. The rusting remains of the giant German-built excavation machine—variously nicknamed either "Sarah" or "Lucy"<ref>{{cite magazine |url=http://www.time.com/time/magazine/article/0,9171,923276-1,00.html |archive-url=https://web.archive.org/web/20121104133215/http://www.time.com/time/magazine/article/0,9171,923276-1,00.html |url-status=dead |archive-date=4 November 2012 |magazine=Time |title=Environment: Sarah Digs a Great Canal |date=10 January 1983 |access-date=24 May 2010}}</ref>—are visible on a [[Google Earth]] image at the south end of the canal, where it has been located since it was disabled by a missile.<ref>[https://www.google.com/maps?q=jonglei+canal&hl=en&ll=6.932647,31.52824&spn=0.009841,0.016512&sll=9.294596,30.168457&sspn=2.504328,4.22699&t=h&hnear=Jonglei+Canal&z=17 Google Earth image]</ref> When peace was restored in 2000, speculation grew about a restart of the project. However, on 21 February 2008, the Sudanese government said the revival of the project was not a priority. Nevertheless, in 2008, Sudan and Egypt agreed to restart the project and finish the canal in 24 years.<ref name="ahmad">Ahmad, A.M. (2008) [http://eau.sagepub.com/cgi/content/abstract/20/2/575?rss=1 Post-Jonglei planning in southern Sudan: combining environment with development] {{webarchive |url=https://archive.today/20130202055818/http://eau.sagepub.com/cgi/content/abstract/20/2/575?rss=1 |date=2 February 2013}} ''[[Environment and Urbanization]]'', October 2008</ref> South Sudan gained independence in 2011.

It is estimated that the Jonglei canal project would produce 3.5–4.8 x 10<sup>9</sup> m<sup>3</sup> of water per year (equal to a mean annual discharge of 110–152 m<sup>3</sup>/s (3 883–5 368&nbsp;ft<sup>3</sup>/s), an increase of around 5–7% of Egypt's current water supply.<ref name="Furniss2010" /> The canal's benefits would be shared by Egypt and Sudan, with the expected damage falling on South Sudan.<ref name="ahmad" /> The complex environmental and social issues involved, including the collapse of fisheries, drying of grazing lands,<ref>{{cite news |url=http://www.gurtong.net/ECM/Editorial/tabid/124/ctl/ArticleView/mid/519/articleId/2718/Jonglei-Canal-Project-is-a-Looming-Catastrophe.aspx |work=Gurtong |title=Jonglei Canal Project Is A Looming Catastrophe |author=Koang Tut Jing |date=8 September 2006 |access-date=22 October 2010 |archive-date=18 July 2011 |archive-url=https://web.archive.org/web/20110718104443/http://www.gurtong.net/ECM/Editorial/tabid/124/ctl/ArticleView/mid/519/articleId/2718/Jonglei-Canal-Project-is-a-Looming-Catastrophe.aspx |url-status=dead}}</ref> a drop of groundwater levels, and a reduction of rainfall in the region,<ref>[[De Villiers, Marq]], 2001. ''Water: The Fate of Our Most Precious Resource''. Mariner Books. {{ISBN|978-0-618-12744-3}}</ref> limits the practicality of the project. The draining of the Sudd is likely to have environmental effects comparable to the drying of [[Lake Chad]] or the draining of the [[Aral Sea]].

==See also==
*[[Okavango Delta]]
*[[Draining of the Mesopotamian Marshes]]

==References==
{{reflist|30em}}

;Bibliography
*Petersen, G., Abya, J. A., Fohrer, N. (2007) [http://www.adv-geosci.net/11/113/2007/adgeo-11-113-2007.pdf Spatio-temporal water body and vegetation changes in the Nile swamps of southern Sudan] ''Advanced Geoscience 11'', 113–116
*Petersen, G., Sutcliffe, J. V., Fohrer, N. (2008) [https://archive.today/20130105072332/http://www3.interscience.wiley.com/journal/119139558/abstract Morphological analysis of the Sudd region using land survey and remote sensing data] ''[[Earth Surface Processes and Landforms]]'', 33
*Petersen, G. (2008) [http://eldiss.uni-kiel.de/macau/receive/dissertation_diss_00003028 ''The Hydrology of the Sudd – Hydrologic Investigation and Evaluation of Water Balances in the Sudd Swamps of Southern Sudan''] University of Kiel, Germany
*Sutcliffe, J.V., Parks, Y.P. (1999) ''The Hydrology of the Nile'', IAHS Special Publication No 5. Wallingford. UK

==Further reading==
*{{cite journal |first=E.A. |last=Stanton |jstor=715130 |title=The Great Marshes of the White Nile |journal=Journal of the Royal African Society |volume=2 |year=1903 |issue=8 |pages=375–379}}
*{{cite journal |last1=Mohamed |first1=Y.A. |last2=van den Hurk |first2=B.J.J.M. |last3=Savenije |first3=H.H.G. |last4=Bastiaanssen |first4=W.G.M. |title=Impact of the Sudd wetland on the Nile hydroclimatology |journal=Water Resources Research |volume=41 |issue=8 |pages=W08420 |year=2005 |bibcode=2005WRR....41.8420M |s2cid=128724157 |doi=10.1029/2004WR003792}}
*{{cite journal |last1=Mohamed |first1=Y.A. |last2=Savenije |first2=H.H.G. |last3=Bastiaanssen |first3=W.G.M. |last4=van den Hurk |first4=B.J.J.M. |title=New lessons on the Sudd hydrology learned from remote sensing and climate modeling |journal=Hydrology and Earth System Sciences |volume=10 |issue=4 |pages=507–518 |year=2006 |bibcode=2006HESS...10..507M |s2cid=2958658 |doi=10.5194/hess-10-507-2006 |doi-access=free}}

==External links==
{{Portal bar|Wetlands}}
{{Commons category|Sudd}}
* {{WWF ecoregion|name=Saharan flooded grasslands|id=at0905}}
* [https://www.reuters.com/article/scienceNews/idUSL2827708220070528 Elephant herds found on isolated south Sudan island]
* [https://web.archive.org/web/20110419212058/http://www.hydroc.de/index-Dateien/p3ewhite.htm Current hydrological and ecological research program on the Sudd swamps]
* [https://maps.google.com/?ll=9.400291,30.500793&spn=1.287076,1.873169&t=k Sudd – on Google Maps]

{{Protected Areas of South Sudan}}
{{Wetlands}}

{{Authority control}}

[[Category:Afrotropical ecoregions]]
[[Category:Ecoregions of South Sudan]]
[[Category:Flooded grasslands and savannas]]
[[Category:Grasslands of South Sudan]]
[[Category:Nile]]
[[Category:Swamps of Africa]]
[[Category:Wetlands of South Sudan]]
[[Category:Ramsar sites in South Sudan]]
[[Category:Important Bird Areas of South Sudan]]