Editing Lake Victoria (section)

==Hydrology and limnology==
Lake Victoria receives 80 percent of its water from direct rainfall.<ref name="Hickling61"/>{{page needed|date = December 2024}} Average evaporation on the lake is between {{convert|2.0| and |2.2|m}} per year, almost double the precipitation of [[riparian]] areas.<ref>{{cite book|author=Ominde, Simeon H. |year=1971|chapter=Rural Economy in West Kenya| chapter-url=https://books.google.com/books?id=WgamvCA98usC&pg=PA220 |title=Studies in East African Geography and Development| pages=207–29| editor=S.H. Ominde|location=London|publisher=Heinemann Educational |isbn=9780520020733}}</ref> Lake Victoria receives its water additionally from rivers, and thousands of small [[stream]]s. The [[Kagera River]] is the largest river flowing into this lake, with its [[river delta|mouth]] on the lake's western shore. Lake Victoria is drained solely by the [[Nile|Nile River]] near [[Jinja, Uganda|Jinja]], Uganda on the lake's northern shore.<ref name="Fishery">{{cite book|url=https://books.google.com/books?id=WLZRxM9vfXoC&pg=PA291|title=Source Book for the Inland Fishery Resources of Africa, Issue 18, Volume 1|last1=vanden Bossche|first1=J.-P.|last2=Bernacsek|first2=G.M.|publisher=[[Food and Agriculture Organization]], [[United Nations]]|year=1990|isbn=9789251029831|page=291|access-date=4 January 2016}}</ref>
[[File:Rift en.svg|thumb|right|Lake Victoria and the [[Great Rift Valley]]]]
{{More citations needed|paragraph|date=June 2017}}
In the Kenya sector, the main influent rivers are the [[Sio River|Sio]], [[Nzoia]], [[Yala River|Yala]], [[Nyando River|Nyando]], [[Sondu Miriu]], [[Mogusi]], and [[Migori]]. The only outflow from Lake Victoria is the Nile River, which exits the lake near Jinja, Uganda. In terms of contributed water, this makes Lake Victoria the principal source of the longest branch of the Nile. However, the most distal source of the Nile Basin, and therefore the ultimate [[Nile#Sources|source of the Nile]], is more often considered to be one of the tributary rivers of the Kagera River (the exact tributary remains undetermined), and which originates in either [[Rwanda]] or [[Burundi]]. The uppermost section of the Nile is generally known as the Victoria Nile until it reaches [[Lake Albert (Africa)|Lake Albert]]. Although it is a part of the same river system known as the [[White Nile]] and is occasionally referred to as such, strictly speaking this name does not apply until after the river crosses the Uganda border into South Sudan to the north.

The lake exhibits [[Eutrophication|eutrophic conditions]]. In 1990–1991, oxygen concentrations in the mixed layer were higher than in 1960–1961, with nearly continuous oxygen supersaturation in surface waters. Oxygen concentrations in [[Hypolimnion|hypolimnetic waters]] (i.e., the layer of water that lies below the [[thermocline]], is noncirculating, and remains perpetually cold) were lower in 1990–1991 for a longer period than in 1960–1961, with values of less than 1&nbsp;mg per litre (< 0.4&nbsp;[[Grain (mass)|gr]]/cu&nbsp;ft) occurring in water as shallow as {{convert|40|m|ft}} compared with a shallowest occurrence of greater than {{convert|50|m|ft}} in 1961. The changes in oxygenation are considered consistent with measurements of higher algal biomass and productivity.<ref>{{cite journal | url=https://www.researchgate.net/publication/240845630  | author1=R.E. Hecky | author2=F.W.B. Bugenyi | author3=P. Ochumba | author4=J.F. Talling | author5=R. Mugidde | author6=M. Gophen | author7=L. Kaufman | year=1994 | title=Deoxygenation of the deep water of Lake Victoria, East Africa | journal=[[Limnology and Oceanography]] | volume=39 | issue=6  |pages=1476–81 | jstor=2838147 | doi=10.4319/lo.1994.39.6.1476| bibcode=1994LimOc..39.1476H | doi-access=free }}</ref> These changes have arisen for multiple reasons: successive burning within its basin,<ref>{{Cite journal | author=R.E. Hecky | year=1993 | title=The eutrophication of Lake Victoria | journal=[[Verhandlungen der Internationale Vereinigung für Limnologie]] | volume=25 | issue=1 | pages=39–48 | doi=10.1080/03680770.1992.11900057| bibcode=1993SILP...25...39H }}</ref> soot and ash from which has been deposited over the lake's wide area; from increased nutrient inflows via rivers,<ref name="OchumbaKibaara">{{cite journal | author1=Peter B. O. Ochumba | author2=David I. Kibaara | year=1989 | title=Observations on blue-green algal blooms in the open waters of Lake Victoria, Kenya | journal=[[African Journal of Ecology]] | volume=27 | issue=1 | pages=23–34  | doi=10.1111/j.1365-2028.1989.tb00925.x| bibcode=1989AfJEc..27...23O }}</ref> and from increased pollution associated with settlement along its shores.<ref>{{Cite news|date=March 2018|title=Environmental and Social Management Framework-ESMF|work=World Bank Document - Early Warning System|url=https://ewsdata.rightsindevelopment.org/files/documents/82/WB-P163782_3UJvON4.pdf|access-date=26 May 2020}}</ref>

Between 2010 and 2022 the surface area of Lake Victoria increased by 15%<ref>{{Cite web |last=Keriako |first=Tobiko |date=2021 |title=Rising Water Levels in Kenya's Rift Valley Lakes, Turkwel Gorge Dam and Lake Victoria |url=http://www.environment.go.ke/wp-content/uploads/2021/10/MENR_Scoping_Report_Latest-5-07-21.pdf |access-date=2022-03-16 |website=Government of Kenya and UNDP |archive-date=28 April 2022 |archive-url=https://web.archive.org/web/20220428030814/http://www.environment.go.ke/wp-content/uploads/2021/10/MENR_Scoping_Report_Latest-5-07-21.pdf |url-status=dead }}</ref> flooding lakeside communities.<ref>{{Cite web |last=Baraka |first=Carey |date=2022-03-17 |title=A drowning world: Kenya's quiet slide underwater |url=https://www.theguardian.com/world/2022/mar/17/kenya-quiet-slide-underwater-great-rift-valley-lakes-east-africa-flooding |access-date=2022-03-17 |website=The Guardian |language=en}}</ref>