{{Short description|Lake in West-Central Africa}} {{About|the lake in Africa|the lake in Antarctica|Lake Chad (Antarctica)}} {{good article}} {{Use dmy dates|date=February 2026}} {{Infobox body of water | name = Lake Chad | native_name = | native_name_lang = | other_name = {{plainlist| *{{native name|Ar|بحيرة تشاد}} *{{native name|kr|Sádǝ}} *{{native name|fr|Lac Tchad}} }} | image = Lake Chad (MODIS 2018-06-07).jpg | caption = Lake Chad in 2018 | location = [[Sahel|Sahelian zone]] at the conjunction of [[Chad]], [[Cameroon]], [[Nigeria]], and [[Niger]] | coordinates = {{coord|13.099|14.533|type:waterbody_globe:earth_region:TD|display=ti}} | inflow = [[Chari River]], [[Yobe River]], [[Ngadda River]] | rivers = | outflow = [[Bahr el-Ghazal (wadi in Chad)|Bahr el-Ghazal]] | catchment = <!-- {{convert|VALUE|UNITS}} must be used --> | basin_countries = [[Chad]], [[Cameroon]], [[Nigeria]], [[Niger]] | pushpin_map = Chad#Cameroon#Niger#Nigeria#Africa | pushpin_label_position = | pushpin_map_alt = Location of Lake Chad in Chad. | designation = | length = <!-- {{convert|VALUE|UNITS}} must be used --> | width = <!-- {{convert|VALUE|UNITS}} must be used --> | area = {{convert|2000 |km2|sqmi|abbr=on}}<ref name=Buma/> | max-depth = {{convert|2|m|ftin|abbr=on}} | volume = <!-- {{convert|VALUE|UNITS}} must be used --> | salinity = | temperature_high = <!-- {{convert|VALUE|UNITS}} must be used --> | temperature_low = <!-- {{convert|VALUE|UNITS}} must be used --> | islands = [[Bogomerom Archipelago]] | sections = | trenches = | benches = | cities = {{Plainlist}} * [[Bol, Chad|Bol]], Chad * [[Abadam]], Nigeria * [[Baga, Borno|Baga]], Nigeria * [[N'guigmi]], Niger * [[Bosso, Niger|Bosso]], Niger * [[Makary, Cameroon|Makary]], Cameroon {{Endplainlist}} | extra = {{Designation list | embed = yes | designation1 = Ramsar | designation1_offname = Lac Tchad | designation1_date = 17 June 2001 | designation1_number = 1072<ref>{{cite web|title=Lac Tchad|website=[[Ramsar Convention|Ramsar]] Sites Information Service|url=https://rsis.ramsar.org/ris/1072|access-date=25 April 2018|archive-date=23 June 2018|archive-url=https://web.archive.org/web/20180623033020/https://rsis.ramsar.org/ris/1072|url-status=live}}</ref> | designation2 = Ramsar | designation2_offname = Partie tchadienne du lac Tchad | designation2_date = 14 August 2001 | designation2_number = 1134<ref>{{cite web|title=Partie tchadienne du lac Tchad|website=[[Ramsar Convention|Ramsar]] Sites Information Service|url=https://rsis.ramsar.org/ris/1134|access-date=25 April 2018|archive-date=23 June 2018|archive-url=https://web.archive.org/web/20180623033008/https://rsis.ramsar.org/ris/1134|url-status=live}}</ref> | designation3 = Ramsar | designation3_offname = Lake Chad Wetlands in Nigeria | designation3_date = 30 April 2008 | designation3_number = 1749<ref>{{cite web|title=Lake Chad Wetlands in Nigeria|website=[[Ramsar Convention|Ramsar]] Sites Information Service|url=https://rsis.ramsar.org/ris/1749|access-date=25 April 2018|archive-date=23 June 2018|archive-url=https://web.archive.org/web/20180623033356/https://rsis.ramsar.org/ris/1749|url-status=live}}</ref> | designation4 = Ramsar | designation4_offname = Partie Camerounaise du Lac Tchad | designation4_date = 2 February 2010 | designation4_number = 1903<ref>{{cite web|title=Partie Camerounaise du Lac Tchad|website=[[Ramsar Convention|Ramsar]] Sites Information Service|url=https://rsis.ramsar.org/ris/1903|access-date=25 April 2018|archive-date=1 February 2020|archive-url=https://web.archive.org/web/20200201104344/https://rsis.ramsar.org/ris/1903|url-status=live}}</ref>}} }} '''Lake Chad''' ({{Langx|ar|بحيرة تشاد}}, [[Kanuri language|Kanuri]]: ''Sádǝ'', {{Langx|fr|Lac Tchad}}) is an [[endorheic]] freshwater lake located at the junction of four countries: [[Nigeria]], [[Niger]], [[Chad]], and [[Cameroon]], in western and central Africa respectively, with a catchment area in excess of {{convert|1000000|km2|sqmi|abbr=on}}. It is an important wetland ecosystem in West-Central Africa. The lakeside is rich in reeds and swamps, and the plain along the lake is fertile, making it an important irrigated agricultural area. The lake is rich in aquatic resources and is one of the important freshwater fish producing areas in Africa.
Lake Chad is divided into deeper southern parts and shallower northern parts. The water source of the lake mainly comes from rivers such as the [[Chari River]] that enter the lake. The water level varies greatly seasonally, and the area of the lake also changes dramatically. During the [[African humid period]], the lake's area reached {{convert|400000|km2|sqmi|abbr=on}}. Due to the increasingly arid climate, the lake surface gradually shrank. In the 19th century, it still had an area of {{convert|28000|km2|sqmi|abbr=on}}. However, due to [[climate change]] and human water diversion, it has shrunk significantly since the mid-1970s, and its area has fluctuated between {{convert|2000|and|5000|km2|sqmi|abbr=on}}.
==Prehistory and history<span class="anchor" id="History"></span>== [[File:Megatschad GIS.PNG|thumb|275px|Lake Chad in [[African humid period]] (blue) and in 20th century (darker green surrounded by blue)|left]] The [[Chad Basin]] was formed by the depression of the [[African Shield]].<ref name=w2/><ref name=hd3/><ref name=r4/> The floor of the basin is made of [[Precambrian]] bedrock covered by more than {{convert|3600|m|abbr=on}} of sedimentary deposits.<ref>{{cite book|last=Obaje|first=Nuhu George|title=Geology and Mineral Resources of Nigeria|url=https://books.google.com/books?id=U1VBp7aItooC&pg=PA69|access-date=2013-05-06|date=2009-08-12|publisher=Springer|isbn=978-3-540-92684-9|page=69}}</ref> For most of the [[Quaternary]], the basin had abundant water sources. Towards the end of this period the climate became drier. Around 20,000–40,000 years ago, [[eolianite]] sand dunes began to form in the north of the basin.<ref>{{cite book|last=Wright|first=J.B.|title=Geology and Mineral Resources of West Africa|url=https://books.google.com/books?id=YBDbdZrHosMC&pg=PA94|access-date=2013-05-06|date=1985-11-30|publisher=Springer|isbn=978-0-04-556001-1|page=95}}</ref> The area of Lake Chad experienced four heydays between 39,000 BC and 300 BC, leaving thick [[diatomaceous earth]] and [[lacustrine deposits]] in the strata. This has been called Mega-Chad. The maximum depth of Mega-Chad exceeded {{convert|180|m|ft|abbr=on}} and it covered an area of approximately {{convert|400000|km2|sqmi|abbr=on}},<ref name=w2/> it flowed into [[Benue River]] through the [[Mayo Kébbi]], which drains into the [[Atlantic Ocean]] through the [[Niger River]].<ref>{{cite journal|last1=Leblanc|first1=M.|last2=Favreau|first2=G.|last3=Maley|first3=J.|last4=Nazoumou|first4=Y.|last5=Leduc|first5=C.|last6=Stagnitti|first6=F.|last7=van Oevelen|first7=P. J.|last8=Delclaux|first8=F.|last9=Lemoalle|first9=J.|year=2006|title=Reconstruction of Megalake Chad using Shuttle Radar Topographic Mission data|journal=Palaeogeography, Palaeoclimatology, Palaeoecology|volume=239|issue=1–2|pages=16–27|doi=10.1016/j.palaeo.2006.01.003|bibcode=2006PPP...239...16L |url=https://www.researchgate.net/publication/222672298|language=en|access-date=2023-06-13|archive-date=2023-06-13|archive-url=https://web.archive.org/web/20230613162944/https://www.researchgate.net/publication/222672298_Reconstruction_of_Megalake_Chad_using_Shuttle_Radar_Topographic_Mission_data}}</ref><ref>{{cite journal |author1=Mathieu Schuster |author2=Claude Roquin |author3=Philippe Duringer |author4=Michel Brunet |author5=Matthieu Caugy |author6=Michel Fontugne |author7=Hassan Taïsso Mackaye |author8=Patrick Vignaud |author9=Jean-François Ghienne |title=Holocene Lake Mega-Chad palaeoshorelines from space |journal=Quaternary Science Reviews |date=2005 |volume=24 |issue=16–17 |pages=1821–1827 |doi=10.1016/j.quascirev.2005.02.001 |bibcode=2005QSRv...24.1821S }}</ref>
The vast waters formed during the [[African humid period]] provided conditions for the emergence of lakeside fishermen's settlements, and the [[Nilo-Saharan]] ethnic group also migrated to Lake Chad during this period. Agriculture also emerged in the [[Sahel]] region at this time.<ref>{{cite book |author= Kevin Shillington |title=History of Africa|date=28 August 2018 |publisher=Macmillan Education UK |url=https://books.google.com/books?id=rxtHEAAAQBAJ|isbn=978-1-137-52481-2 |pages=19–31 }}</ref> By 1800 BC, a [[pottery]] culture known as Gajiganna had emerged, initially as pastoralists, but, starting around 1500 BC, living in settled hamlets at the side of the lake.<ref>{{cite journal |last=Ogundiran |first=Akinwumi |year=2005 |title=Four Millennia of Cultural History in Nigeria (ca. 2000 B.C.–A.D. 1900): Archaeological Perspectives |journal=Journal of World Prehistory |volume=19 |issue=2 |page=138 |doi=10.1007/s10963-006-9003-y}}</ref> The archaeological discovery revealed wild grasses, mostly of the tribe [[Paniceae]], and wild rice together with the earliest domesticated [[Pearl millet]] in the Lake Chad region, dating to 1200–1000 [[Radiocarbon calibration|cal BC]]. One of the oldest domesticated Pearl millet in West Africa was found in the Chad Basin, charred together with wild grasses, and their era can be traced back to 800–1000 cal BC.<ref>{{cite book |author1=Marlies Klee |author2=Barbara Zach |chapter=The Exploitation of Wild and Domesticated Food Plants at Settlement Mounds in North-East Nigeria (1800 cal BC to Today) |title=The Exploitation of Plant Resources in Ancient Africa |date=1999 |pages=81–88 |doi=10.1007/978-1-4757-6730-8_8|isbn=978-1-4419-3316-4 }}</ref>
Permanent villages were established to the south of the lake by 500 BC,<ref name=fzn1>{{cite book|last=Decorse|first=Christopher R.|title=West Africa During the Atlantic Slave Trade: Archaeological Perspectives|url=https://books.google.com/books?id=8Fcr1HSZXNgC&pg=PA103|access-date=2013-05-06|year=2001|publisher=Continuum International Publishing Group|isbn=978-0-7185-0247-8|page=103}}</ref> and major archaeological discoveries include the [[Sao civilization]].<ref name=w2/> According to the records of [[Claudius Ptolemy]] in the mid-2nd century AD, the Romans of the 1st century AD had already [[Romans in sub-Saharan Africa|come into contact]] with Lake Chad through their connections with Tunisia, [[Tripolitania]], and [[Fezzan]].<ref>{{Cite journal|last=Johnston|first=H. H.|date=1910|title=Lake Chad|journal=Nature|language=en|volume=84|issue=2130|pages=244–245|doi=10.1038/084244a0|bibcode=1910Natur..84..244J|s2cid=8682184|issn=1476-4687}}</ref> By the 5th century AD camels were being used for [[trans-Saharan trade]] via the Fezzan, or to the east via [[Darfur]].<ref name=eof1>{{cite book|last1=Appiah|first1=Kwame Anthony|last2=Gates|first2=Henry Louis Jr.|title=Encyclopaedia of Africa|url=https://books.google.com/books?id=A0XNvklcqbwC&pg=PA254|access-date=2013-05-06|year=2010|publisher=Oxford University Press|isbn=978-0-19-533770-9|page=254}}</ref> After the Arabs conquered North Africa during the 7th and 8th centuries, the Chad Basin became increasingly linked to the Muslim countries.<ref name=fzn1/>
Trade and improved agricultural techniques enabled more sophisticated societies.<ref name=eof1/> Around 900 AD, the Kanem people who spoke the [[Kanuri language]] unified numerous nomadic tribes and established the [[Kanem Empire]] in the northeast of Lake Chad. At the beginning of the founding of the country, the Kanem people continued to live a nomadic life until the 11th century, when they were Islamized and settled in [[Njimi]]. Through [[trans-Saharan trade]], the power of the Kanem Empire reached its peak in the 13th century, but as the empire declined in the 14th century, its southwestern vassal state of [[Bornu Empire|Bornu]] began to rise, causing the power center of the empire to shift to Bornu around 1400. In 1574 the [[Ottoman Empire]] had invaded [[Fezzan]] and the Oasis,<ref>{{Cite book |last=Lange |first=Dierk |url=https://books.google.com/books?id=syATJKcx5A0C&pg=PA546 |title=Ancient Kingdoms of West Africa: African-centred and Canaanite-Israelite Perspectives ; a Collection of Published and Unpublished Studies in English and French |date=2004 |publisher=J.H.Röll Verlag |isbn=978-3-89754-115-3 |language=en}}</ref> and even reached into Lake Chad. This was the deepest Ottoman incursion into the interior of Africa before the nineteenth century. The Ottoman Empire extended its influence on central region of the [[Sahel|Central Sahel]] during the reign of [[Murad III]], And Lake Chad becoming a part of Ottoman sphere of influence,<ref>{{Cite journal |last=Flynn |first=Sébastien |date=2016-01-01 |title=THE RELATIONSHIP BETWEEN THE OTTOMAN EMPIRE AND KANEM- BORNU DURING THE REIGN OF SULTAN MURAD III A Master's Thesis |url=https://www.academia.edu/40148198 |journal=Bilkent Master's Thesis}}</ref> and in the second half of the 16th century, the Bornu Empire began importing firearms from the ottoman Empire, consolidating its military hegemony. The Bornu Empire declined in the 18th century, and later lost its western region to the [[Sokoto Caliphate]] during the early 19th century. It was later colonised by European powers in the 20th century.<ref>{{cite book |author= Kevin Shillington |title=History of Africa |date=28 August 2018 |publisher=Macmillan Education UK |url=https://books.google.com/books?id=rxtHEAAAQBAJ|isbn=978-1-137-52481-2 |pages=101–103+188–190+249–256 }}</ref>
Following the growing interest in Africa among European academic and business communities, the Lake Chad area was extensively described by Europeans in the 19th century. Three scientific expeditions were conducted between 1898 and 1909.<ref name=w2/> During the [[Berlin Conference]] in 1884–1885, Africa was divided between the European colonial powers. By the second decade of the 20th century, Lake Chad had been colonized and occupied by [[British Empire|Britain]], [[French colonial empire|France]], and [[German colonial empire|Germany]], defining boundaries that are largely intact with the present [[Decolonisation of Africa|post-colonial states]].<ref>{{cite book|last=Harlow|first=Barbara|title=Colonialism|chapter-url=https://books.google.com/books?id=qFTHBoRvQbsC&pg=PA139|access-date=2013-05-06|year=2003|publisher=ABC-CLIO|isbn=978-1-57607-335-3|chapter=Conference of Berlin (1884–1885)|page=139}}</ref><ref name=hea3>{{cite news |title=乍得湖：从"文明摇篮"到"死亡之心" |trans-title=Lake Chad: From "Cradle of Civilization" to "Heart of Death" |author1=熊正坤 |author2=张瑾 |url=http://www.chinawater.com.cn/newscenter/jlkt/202104/t20210408_763432.html |access-date=2024-01-01 |publisher=China Water Resources News |date=2021-04-08 |archive-date=1 January 2024 |archive-url=https://web.archive.org/web/20240101065102/http://www.chinawater.com.cn/newscenter/jlkt/202104/t20210408_763432.html |url-status=live }}</ref> At the beginning of independence, the countries surrounding Lake Chad not only had a poor economic foundation, but also had more complex ethnic, religious, and political conflicts. [[Nigeria]] and [[Niger]], which had just gained independence, experienced continuous coups, while Chad also experienced ongoing civil war. The inability of countries along the lake to consider the protection of Lake Chad has led to a series of environmental problems.<ref name=hea3/>
==Geography== [[File:Charirivermap.png|thumb|275px|Map showing the Chari River drainage basin|left]] The Chad Basin includes [[Chad]], Nigeria, [[Cameroon]], Niger, [[Sudan]], and the [[Central African Republic]].<ref>{{cite web|url=https://cblt.org/wp-content/uploads/2021/06/about-map.jpg|title=about-map|access-date=2024-03-26|work=Lake Chad Basin Commission}}</ref> It is an extensional fault depression type [[rift basin]], which can be divided into four secondary [[structural unit]]s: southern depression, northern depression, central uplift, and eastern slope. The southern depression of the basin is characterized by an asymmetric fault depression composite rift with steep slopes in the east and gentle slopes in the west on the profile, and is distributed in an NNW direction on the plane. There are two large basin‐bounding normal [[fault (geology)|faults]] developed on both sides of the basin, with a [[graben]] style fault and [[depression (geology)|depression]] in the middle. The east and west sides are outward dipping low angle gentle slope areas. The eastern boundary fault is steep with a dip angle of about 55°, while the western fault has a dip angle of about 45°. The overall thickness of the inner layer in the slope area is relatively thin. In the central area of the basin, the thickness of the sedimentary strata is large, and the thickness of the sedimentary center zone reaches over {{convert|10000|m|ft|abbr=on}}. The northern part of the basin appears steep in the west and gentle in the east on the profile. Five fault structural zones parallel to the basin‐bounding faults have developed from west to east.<ref>{{cite journal |title=乍得湖盆地构造特征与油气成藏规律初探 |trans-title=A preliminary study on the tectonic characteristics and hydrocarbon accumulation law of the Lake Chad Basin |author1=黄先雄|author2=夏斌|author3=万志峰|author4=吕宝凤|author5=蔡周荣|journal=大地构造与成矿学 |date=2008 |issue=3 |pages=326–331 |doi=10.16539/j.ddgzyckx.2008.03.013}}</ref>
Lake Chad is divided into north and south parts by a shallow sill called the Great Barrier, with the bottom of the northern basin at an altitude of {{convert|275.3|m|ft|abbr=on}} and the bottom of the southern basin at {{convert|278.2|m|ft|abbr=on}}. When the water level in the south exceeds {{convert|279|m|ft|abbr=on}} above sea level, it will flow into the north.<ref name=7g/> In the south, there is continuous open water at the mouth of the Chari River, and the western part of the water is covered by reed swamps,<ref name=h8>{{cite journal |author1=Marie-Thérèse Sarch |author2=Charon Birkett |title=Fishing and farming at Lake Chad: Responses to lake-level fluctuations |journal=The Geographical Journal |date=June 2000 |volume=166 |issue=2 |pages=156–172 |doi=10.1111/j.1475-4959.2000.tb00015.x |jstor=823109 |bibcode=2000GeogJ.166..156S }}</ref> and the sand dunes that are not completely submerged in the eastern waters form an archipelago.<ref name=r4/> The average depth of the southern lake basin is between {{convert|.5|and|2|m|ftin|abbr=on}}, that of the northern lake basin is between 0 and {{convert|1.8|m|ftin|abbr=on}}, and that of the eastern archipelago is between 0 and {{convert|2|m|ftin|abbr=on}}.<ref>{{cite journal |author1=Jacques Lemoalle |author2=Jean-Claude Bader |author3=Marc Leblanc |author4=Ahmed Sedick |title=Recent changes in Lake Chad: Observations, simulations and management options (1973–2011) |journal=Global and Planetary Change |date=January 2012 |volume=80–81 |issue=247–254 |pages=247–254 |doi=10.1016/j.gloplacha.2011.07.004|bibcode=2012GPC....80..247L }}</ref>
The climate of the Lake Chad region is strongly influenced by continental and maritime [[air mass]]es. The maritime air mass moves northward during the summer, producing seasonal precipitation. In late summer, continental air mass dominate again.<ref name=w2/> The average annual precipitation in the Lake Chad area is {{convert|330|mm|in|0|abbr=on}}, with an average annual precipitation of {{convert|560|mm|in|1|abbr=on}} on the south bank and about {{convert|250|mm|in|1|abbr=on}} on the north bank. The highest temperature in the rainy season is {{cvt|30|C|F}}, and the highest temperature rises to more than {{convert|32|C|F|abbr=on}} when October and November enter the dry season. The temperature difference between day and night is almost twice that of the rainy season, and the lowest nighttime temperature sometimes drops to {{convert|8|C|F|abbr=on}} in December and January. April is usually the hottest month of the year, with temperatures occasionally reaching {{convert|40|C|F|abbr=on}}, the lowest water levels appear in June to July, and the highest water levels in November to December, with surface water temperatures ranging from {{convert|19|to|32|C|F|abbr=on}}.<ref name=w2>{{cite encyclopedia |last1=Gritzner |first1=J. A. |title=Lake Chad |encyclopedia=Encyclopedia Britannica |location=Chicago |publisher=Encyclopædia Britannica, Inc. |url=https://www.britannica.com/place/Lake-Chad |access-date=2023-06-13 |language=en |archive-date=22 July 2019 |archive-url=https://web.archive.org/web/20190722235543/https://www.britannica.com/place/Lake-Chad |url-status=live }}</ref><ref name=r4/>
==Hydrology== [[File:Megachad en disappearance of lake chad.jpg|thumb|346x346px|Shrinking of Lake Chad over the last 7000 years, with the outline of the [[British Isles]] for size comparison]] [[File:Lake Chad.jpg|thumb|right|275px|Lake Chad 1972–2007]] The Chad Basin covers an area of about {{convert|1|e6km2|sqmi|abbr=on}}, and is injected by the [[Chari River|Chari]], [[Logone River|Logone]], and [[Yobe River]]s.<ref name=r4>{{cite encyclopedia |author=Wen Yunzhao |title=Lake Chad |encyclopedia=Encyclopedia of China |edition=03 |location=Beijing |publisher=Encyclopedia of China Publishing House |url=https://www.zgbk.com/ecph/words?SiteID=1&ID=563293 |access-date=2023-06-11 |language=zh-cn |archive-date=13 June 2023 |archive-url=https://web.archive.org/web/20230613163405/https://www.zgbk.com/ecph/words?SiteID=1&ID=563293 |url-status=live }}</ref><ref name=w2/> The water supply of the lake is seasonal. Most of the precipitation comes from the [[Adamawa Plateau]] in the south of the basin, which is transported to the lake basin through the Chari River and the Logone River. The two contribute 95% of the total inflow of Lake Chad, while the Yobe River only contributes less than 2.5%.<ref name=hd3/> The lake seeps through the underground to the lowest point of the Chad Basin, the [[Bodélé Depression]], approximately {{convert|480|km|mi|abbr=on}} northeast of Lake Chad, with the deepest point reaching an elevation of only {{convert|155|m|ft|abbr=on}} above sea level. This takes away most of the salinity and maintains the low salinity of Lake Chad. The southwestern waters of Lake Chad being freshwater, and the water in the northeast is only slightly salty.<ref name=4d>{{cite journal |author1=袁宣民 |title=乍得湖的环境、安全及其脆弱性 |trans-title=The environment, security and vulnerability of Lake Chad |journal=世界科学 |date=2016 |issue=7 |pages=21–23 |url=https://worldscience.cn/c/2016-07-14/587434.shtml |language=zh-cn |access-date=2023-06-13 |archive-date=2023-03-21 |archive-url=https://web.archive.org/web/20230321201808/https://worldscience.cn/c/2016-07-14/587434.shtml }}</ref><ref name=hd3/>
The water volume of most large lakes in Africa depends on rainfall and evaporation, which means that temperature and precipitation are crucial for regulating the water balance of these bodies of water, and any fluctuations can cause significant changes in their water level and area.<ref>{{cite journal |author1=Richard Ogutu-Ohwayo |author2=Vianny Natugonza |author3=Laban Musinguzi |author4=Mark Olokotum |author5=Shamim Naigaga |title=Implications of climate variability and change for African lake ecosystems, fisheries productivity, and livelihoods |journal=Journal of Great Lakes Research |volume=42 |issue=3 |pages=498–510 |doi=10.1016/j.jglr.2016.03.004 |year=2016|bibcode=2016JGLR...42..498O }}</ref> Lake Chad is a shallow inland lake, and the rainfall in the Chad basin is very sensitive to small changes in atmospheric circulation, so the surface area of Lake Chad is greatly affected by climate change.<ref name=f1/><ref>{{cite journal |last1=Leblanc |first1=M. |last2=Favreau |first2=G.|last3=Tweed |first3=S. |title=Remote sensing for groundwater modelling in large semiarid areas:Lake Chad Basin, Africa |journal=Hydrogeology Journal |year=2007 |volume=15 |issue=1 |pages=97–100 |doi=10.1007/s10040-006-0126-0 |bibcode=2007HydJ...15...97L |url=https://www.researchgate.net/publication/29650900 |language=en }}</ref> Dry climate due to vegetation loss from overgrazing and deforestation and large-scale irrigation projects that diverted water from the rivers that feed the lake are the main reasons for the shrinkage of Lake Chad.<ref name=tr5/> The [[Atlantic multidecadal oscillation]] and the [[El Niño–Southern Oscillation]] have affected precipitation in the [[Sahel]] region. From the early 1960s to the mid-1980s, the lake water level decreased by {{convert|3|m|ft|abbr=on}} compared to the average level from 1900 to 2010.<ref>{{cite journal |title=Combined effect of El Niño southern oscillation and Atlantic multidecadal oscillation on Lake Chad level variability |author1=Churchill Okonkwo |author2=Belay Demoz |author3=Ricardo Sakai |author4=Charles Ichoku |author5=Chigozie Anarado |author6=Jimmy Adegoke |author7=Angelina Amadou |author8=Sanusi Imran Abdullahi |author9=Nir Krakauer |journal=Cogent Geoscience |date=2015-12-15 |volume=1 |issue=1 |doi=10.1080/23312041.2015.1117829 |doi-access=free }}</ref>
In 1870, the area of Lake Chad was about {{convert|28000|km2|sqmi|abbr=on}}. The lake was able to flow out of the [[Bahr el-Ghazal (wadi in Chad)|Bahr el-Ghazal]] during the rainy season. At the turn of the 20th century the area of Lake Chad shrank briefly, and reached a new high in the middle of the 20th century and overflowed from the Bahr el-Ghazal again.<ref name=w2/> A major drought started in the Sahel region in the late 1960s and caused severe damage in 1972 and 1984. It was thought to be related to vegetation loss, global warming, and sea surface temperature anomalies.<ref name=f1>{{cite book|last=Evans|first=T.|chapter=The effects of changes in the world hydrological cycle on availability of water resources|editor-last1=Bazzaz|editor-first1=F.|editor-last2=Sombroek|editor-first2=W.|title=Global climate change and agricultural production|year=1996|publisher=FAO / John Wiley & Sons|isbn=92-5-103987-9|chapter-url=https://www.fao.org/3/W5183E/w5183e04.htm |archive-date=2023-06-18 |archive-url=https://web.archive.org/web/20230618010145/https://www.fao.org/3/W5183E/w5183e04.htm |language=en }}</ref> During this period, Lake Chad shrunk considerably and fluctuated in the range of {{convert|2000|to|5000|km2|sqmi|abbr=on}} thereafter.<ref name=7g/>
From June 1966 to January 1973, the area of Lake Chad shrank from {{convert|22772|to|15400|km2|sqmi|abbr=on}},<ref name=tr5>{{cite web|url=http://www.unep.org/dewa/vitalwater/article116.html|title=Lake Chad: almost gone|publisher=[[United Nations Environment Programme]] (UNEP)|access-date=2015-12-05|archive-url=https://web.archive.org/web/20081216142751/http://www.unep.org/dewa/vitalwater/article116.html|archive-date=2008-12-16}}</ref> further shrunk to {{convert|4398|km2|sqmi|abbr=on}} in 1975,<ref name=7g/> and only {{convert|1756|km2|sqmi|abbr=on}} in February 1994.<ref name=tr5/> Since then, the area of Lake Chad has entered a relatively stable stage with a slight increase.<ref>{{cite journal |author1=Wengbin Zhu |author2=Jiabao Yan|author3=Shaofeng Jia |title=Monitoring Recent Fluctuations of the Southern Pool of Lake Chad Using Multiple Remote Sensing Data: Implications for Water Balance Analysis |journal=Remote Sensing |date=2017 |page=1032 |issue=10|volume=9|doi=10.3390/rs9101032 |doi-access=free |bibcode=2017RemS....9.1032Z }}</ref> From 1995 to 1998, it fluctuated within the range of {{convert|1200|to|4500|km2|sqmi|abbr=on}}. The area once reached {{convert|5075|km2|sqmi}} in 2000,<ref name=7g>{{cite journal |author1=刘甜甜 |author2=刘荣高 |author3=葛全胜 |title=基于多源遥感数据的非洲乍得湖水面变化监测 |trans-title=Monitoring of water surface change in Lake Chad in Africa based on multi-source remote sensing data|journal=地理科学进展 |year=2013 |volume=32 |issue=6 |pages=906–912 |doi=10.11820/dlkxjz.2013.06.007 |doi-access=free |language=zh-cn}}</ref> and the average area of surface water from 2013 to 2016 was about {{convert|1876|km2|sqmi|abbr=on}}, with the largest area being {{convert|2231|km2|sqmi|abbr=on}} in July 2015.<ref name=Buma>{{cite journal |author1=Willibroad Gabila Buma |author2=Sang-Il Lee |author3=Jae Young Seo |title=Recent surface water extent of Lake Chad from multispectral sensors and GRACE |journal=Sensors |date=2018 |doi=10.3390/s18072082|issue=7|volume=18|page=2082 |pmid=29958481 |pmc=6069056 |doi-access=free |bibcode=2018Senso..18.2082B }}</ref>
=== Quaternary aquifer and groundwater resilience === Beneath the lake lies the unconfined Quaternary phreatic aquifer, a massive transboundary water resource spanning approximately 500,000 square kilometers across Chad, Niger, Nigeria, and Cameroon.<ref name="Nour2022">{{cite journal |last1=Mahamat Nour |first1=A. |last2=Huneau |first2=F. |last3=Mahamat Ali |first3=A. |last4=Vystavna |last5=Y. |date=2022 |title=Shallow Quaternary groundwater in the Lake Chad basin is resilient to climate change but requires sustainable management strategy: Results of isotopic investigation |journal=Science of The Total Environment |volume=848 |article-number=158152 |doi=10.1016/j.scitotenv.2022.158152}}</ref> While the lake loses approximately 2,200mm/year of water to potential evapotranspiration, isotopic studies utilizing stable isotopes and tritium show that the underlying groundwater system remains highly resilient to climate change.<ref name="Nour2022" /><ref name="Goni2021">{{cite journal |last1=Goni |first1=I. B. |last2=Sherif |first2=A. M. |last3=Taylor |first3=R. G. |date=2021 |title=Groundwater recharge from heavy rainfall in the southwestern Lake Chad Basin: evidence from isotopic observations |journal=Hydrological Sciences Journal |volume=66 |issue=10 |pages=1521–1534 |doi=10.1080/02626667.2021.1937630}}</ref>
The Quaternary aquifer actively recharges through two primary processes: direct infiltration of intense seasonal rainfall events and lateral seepage from the lake itself and its ephemeral river channels.<ref name="Goni2021" /> Isotopic data demonstrates that heavy rainfall exceeding the 60th percentile of monthly precipitation intensity drives the majority of the diffuse recharge, meaning that the projected intensification of tropical downpours under global warming actually favors groundwater replenishment within the basin.<ref name="Goni2021" /> This extensive subsurface reservoir provides a critical hydrological buffer, ensuring permanent water access for municipal and agricultural pumping despite extreme surface-water variability.<ref name="Nour2022" />
==Ecology== [[File:Kanał doprowadzający do jeziora - Jezioro Czad - 001269s.jpg|thumb|275px|[[Lake Chad flooded savanna]]]] Part of the Chad Basin is located within the [[Chad Basin National Park]] in Nigeria, and the country and Cameroon have established the Lake Chad Ramsar Wetland with a total area of {{convert|8225|km2|sqmi|abbr=on}}.<ref name=tgd1/>
===Plantlife=== The wetland plants in the south mainly include [[cyperus papyrus]], etc. [[Reed (plant)|Reeds]] mainly grow in the north where the salinity is high, and the floating plant [[pistia]] sometimes covers large areas of open water. Plants such as [[hyparrhenia rufa]] grow on the shores of lakes with long floods in the south.<ref name=tgd1/> The area of permanent vegetation has increased from about {{convert|3800|km2|sqmi|abbr=on}} in 2000 to about {{convert|5200|km2|sqmi|abbr=on}} in 2020 as water levels have dropped and temperatures have increased.<ref>{{cite journal |author1=Binh Pham-Duc |author2=Florence Sylvestre |author3=Fabrice Papa |author4=Frédéric Frappart |author5=Camille Bouchez |author6=Jean-Francois Crétaux |title=The Lake Chad hydrology under current climate change |journal=Scientific Reports |date=2020 |volume=10 |issue=5498 |page=5498 |doi=10.1038/s41598-020-62417-w|doi-access=free |pmid=32218517 |pmc=7099084 |bibcode=2020NatSR..10.5498P }}</ref> The surrounding dense woodland has been converted to open forest with [[acacias]], [[baobabs]], [[Arecaceae|palms]] and [[Indian jujube]].<ref name=w2/>
===Birds=== The lake has been designated an [[Important Bird Area]] (IBA) by [[BirdLife International]].<ref name=bli>{{cite web |url= https://datazone.birdlife.org/site/factsheet/lake-chad-iba-chad|title= Lake Chad |author=<!--Not stated--> |date=2024|website= BirdLife Data Zone|publisher= BirdLife International|access-date= 2024-10-30}}</ref> It is permanently or seasonally inhabited by hundreds of species of birds such as [[northern shoveler]], [[Egyptian goose]] and [[marabou stork]].<ref name=w2/> It is an important wintering ground for European [[anatidae]] and wading birds. There are raptors such as [[steppe eagle]] and [[booted eagle]] on the lakeshore,<ref name=tgd1>{{cite web |author1=Emma Martin |author2=Neil Burgess |title=Lake Chad Flooded Savanna |url=https://www.oneearth.org/ecoregions/lake-chad-flooded-savanna/ |website=www.oneearth.org |date=15 December 2021 |access-date=2023-07-15 |archive-date=15 July 2023 |archive-url=https://web.archive.org/web/20230715052429/https://www.oneearth.org/ecoregions/lake-chad-flooded-savanna/ |url-status=live }}</ref> and more than one million [[Ruff (bird)|ruff]] can be observed on the lake at one time.<ref name=4j>{{cite report |last1=Keith |first1=J. O. |last2=Plowes |first2=D. C. H. |title=Considerations of Wildlife Resources and Land Use in Chad |date=March 1997 |page=3 |url=https://pdf.usaid.gov/pdf_docs/PNABZ699.pdf |docket=SD Technical Paper No. 45 |publisher=Office of Sustainable Development, Africa Bureau, USAID |archive-date=2023-06-18 |archive-url=https://web.archive.org/web/20230618010146/https://pdf.usaid.gov/pdf_docs/PNABZ699.pdf |language=en}}</ref>
===Mammals=== The once common large mammals include [[red-fronted gazelle]], [[dama gazelle]], [[patas monkey]], [[striped hyena]], [[cheetah]] and [[caracal]], while [[African elephant]], [[otter]], [[hippopotamus]], [[sitatunga]] and [[kob]] are distributed in the wetlands. At present, most of the large mammals have been hunted to extinction, replaced by a large number of cattle.<ref name=tgd1/>
===Fish=== The entire Chad Basin has 179 species of fish, of which 127 are the same as the Niger River Basin, 85 are the same as the Nile River Basin, 47 are the same as the [[Congo River Basin]], and 84 fish species are distributed in the lake.<ref name=hd3>{{cite book |last1=Hughes |first1=R. H. |last2=Hughes |first2=J. S. |year=1992 |title= A Directory of African Wetlands |publisher=[[IUCN]] / [[UNEP]] / [[World Conservation Monitoring Centre|WCMC]] |isbn=2-88032-949-3 |pages=329–330 |url=https://portals.iucn.org/library/sites/library/files/documents/1992-007.pdf |language=en |url-status=live |access-date=2023-06-14 |archive-date=2012-09-24 |archive-url=https://web.archive.org/web/20120924181446/http://ramsar.wetlands.org/Portals/15/CHAD.pdf }}</ref> This makes it a rich fishing ground for communities across Nigeria, Niger, Chad, and Cameroon. The seasonal influx of floods combined with seasonal increases in air temperature leads to decreased salinity, increased turbidity, and increased trophic levels, which catalyzed a surge in the number of phytoplankton and zooplankton, allowing large fish to migrate seasonally within the watershed to feed and breed in the fertile floodplain when floods arrive.<ref name=h8/>
==Human activities== [[File:ShrinkingLakeChad-1973-1997-EO.jpg|thumb|right|Lake Chad in a 2001 satellite image. The lake has shrunk by 95% since the 1960s.<ref>{{cite web |title=Plan B Updates - 47: Disappearing Lakes, Shrinking Seas - EPI |url=http://www.earth-policy.org/index.php?/plan_b_updates/2005/update47 |work=earth-policy.org}}</ref><ref>{{cite web |title=Shrinking African Lake Offers Lesson on Finite Resources |url=http://news.nationalgeographic.com/news/2001/04/0426_lakechadshrinks.html |archive-url=https://web.archive.org/web/20010430065144/http://news.nationalgeographic.com/news/2001/04/0426_lakechadshrinks.html |archive-date=April 30, 2001 |work=nationalgeographic.com}}</ref>]] [[File:Building a house in lake Chad region.jpg|thumb|right|275px|Building a temporary house in Lake Chad region]] There are more than 30 million residents in the Chad Lake Basin. There are more than 70 ethnic groups around the lake, most of whom are distributed on the south bank, where the population density exceeds {{convert|100|PD/km2|PD/sqmi|abbr=on}}. They rely on the water source of Chad Lake for irrigation, breeding, animal husbandry and drinking.<ref name="4d" /> Local self-sufficient crops include [[sorghum]], [[maize]], [[finger millet]], [[beans]], and [[vegetables]]. Gourd is widely planted for making utensils. The collection of forest products such as [[gum arabic]], [[honey]], [[beeswax]], and [[firewood]] is of great significance in the region. However, the reduction in forest area has had a negative impact on the production of these products, and the explosive growth of [[cattle]] herds has exacerbated this impact. Cattle are the most important livestock raised, as well as [[poultry]], [[goats]], [[sheep]], [[camels]], [[horses]], and [[donkeys]]. The [[animal husbandry]] was severely affected by the droughts of the 1970s and 1980s.<ref name=w2/>
Fishing has traditionally been the most important economic activity for the people of the lake area, which almost ceased during drought periods and only resumed in the mid-1990s. Most fishing products are dried, pickled, or smoked. The [[natron]] produced in the depression on the northeast bank of the lake has long been of economic significance. Traditionally, it has been excavated in blocks and transported across the lake to enter the Nigerian market.<ref name=w2/> Since the drought in the 1970s, the soil that can be planted without irrigation and fertilization has been exposed at the bottom of the lake, and it has been reclaimed as a [[polder]] for planting maize, [[cowpea]], [[rice]], sorghum and other crops.<ref>{{cite journal|last1=Luxereau|first1=A.|last2=Genthon|first2=P.|last3=Ambouta|first3=J.-M. K.|year=2011|title=Fluctuations in the Size of Lake Chad: Consequences on the Livelihoods of the Riverain Peoples in Eastern Niger|journal=Regional Environmental Change|volume=12|issue=3|pages=507–521|doi=10.1007/s10113-011-0267-0|url=https://www.researchgate.net/publication/257480536|language=en|access-date=2023-06-13|archive-date=2023-06-14|archive-url=https://web.archive.org/web/20230614102927/https://www.researchgate.net/publication/257480536_Fluctuations_in_the_Size_of_Lake_Chad_Consequences_on_the_Livelihoods_of_the_Riverain_Peoples_in_Eastern_Niger}}</ref> Farmers have shifted from planting mainly dry crops, such as wheat, to rice with high water demand, resulting in more serious soil salinization and water eutrophication.<ref name="4d" /> The adverse effects of reduced water sources on fishing, farming, and herding outweigh the benefits of new land from the receding waters. The surrounding residents who used to rely on lake water were forced to relocate, causing the economy of the lake area to continuously shrink.<ref>{{Cite web |title=The Effects of Climate Change in the Poorest Countries: Evidence from the Permanent Shrinking of Lake Chad |url=https://openknowledge.worldbank.org/handle/10986/40328 |date=2023-09-05|access-date=2024-04-08 |website=World Bank |language=en|author1=Roman D. Zarate|author2=Remi Jedwab|author3=Federico Haslop|author4=Carlos Rodríguez-Castelán}}</ref>
Since 1970, five countries in the southern part of the basin have constructed numerous water conservancy projects in the upper reaches of the Chari River, Logone River, and Yobe River to intercept river water, resulting in a sharp decrease in the amount of water entering the lake. The average annual inflow of the Chari River and the Logone River from 1970 to 1990 was only 55% of that from 1950 to 1970. Since the 1980s, one-third of the water in the Chari River and the Logone River has been diverted and intercepted by the Central African Republic located upstream for agricultural irrigation and hydroelectric power generation.<ref name=4d/> The dams built on the upper reaches of the rivers entering the lake changed the time and scope of seasonal floods and disrupted the migration of fish, resulting in a sharp reduction in the populations of ''[[Alestes baremoze]]'' and [[Nile perch]], the main catches of Lake Chad, and a significant reduction in the catch.<ref name=4j/><ref name=hd3/> At the same time, the conflicts between countries and ethnic groups competing for water and land are also escalating. The four countries along the lake are all facing the problem of extreme poverty, and due to the difficulty in meeting their livelihoods, some local residents have been involved in drug and arms trade.<ref name=4d/> This has been exacerbated by the activity of [[Boko Haram]], an insurgency that has displaced millions of people and disrupted development through the region.<ref>{{cite journal |last1=Olowoyeye |first1=Oluwatuyi S. |last2=Kanwar |first2=Rameshwar S. |year=2023 |title=Water and Food Sustainability in the Riparian Countries of Lake Chad in Africa |journal=Sustainability |volume=15 |number=13 |page=10009:2 |doi=10.3390/su151310009 |doi-access=free|bibcode=2023Sust...1510009O }}</ref>
Cameroon, Niger, Nigeria, and Chad established the [[Lake Chad Basin Commission]] on 22 May 1964. The Central African Republic joined in 1996, and [[Libya]] joined in 2008. The headquarters of the committee is located in [[N'Djamena]], Chad. The commission's tasks include managing Lake Chad and its water resources, protecting the ecosystem, and promoting regional integration, peace, security, and development in the Lake Chad region.<ref name=abu2>{{cite web |title=About us |url=https://cblt.org/about-us/ |website=Lake Chad Basin Commission |access-date=2023-07-15 |archive-date=15 July 2023 |archive-url=https://web.archive.org/web/20230715161538/https://cblt.org/about-us/ |url-status=live }}</ref> The surrounding countries' water replenishment plan for Lake Chad includes the construction of a {{convert|2400|km|mi|abbr=on}} [[Lake Chad replenishment project|canal]] to transport {{convert|100|e9m3|e9yd3|abbr=on}} of water from the Congo River Basin to the Chari River Basin every year, and use a series of dams along the route to generate electricity.<ref>{{Cite news|url=https://www.bbc.com/news/world-africa-43500314|title=Can the vanishing lake be saved?|last=Ross|first=Will|date=2018-03-31|work=BBC|access-date=2019-01-28|language=en-GB|archive-date=9 August 2019|archive-url=https://web.archive.org/web/20190809092459/https://www.bbc.com/news/world-africa-43500314|url-status=live}}</ref>
==See also== {{Portal|Lakes|Earth sciences|Water}} * [[Inner Niger Delta]], an inland delta in Mali * [[Lake Ptolemy]], former lake in Sudan * [[List of drying lakes]] * [[Sudd]], vast swamp in South Sudan * [[Wildlife of Chad]] * {{Annotated link|Lake Chad replenishment project}}
==References== {{reflist}}
==Further reading== *{{cite book |last1=Hughes |first1=R. H. |last2=Hughes |first2=J. S. |year=1992 |title=A Directory of African Wetlands |publisher=[[IUCN]] |isbn=978-2-88032-949-5 }} *{{cite book |last= Beadle |first=L. C. |year=1974 |title=The Inland Waters of Tropical Africa: An Introduction to Tropical Limnology Hardcover |edition=1th |publisher=Longman Publishing Group |isbn=978-0-582-44852-0 }} *{{cite book |last1=Chapman |first1=Graham |last2=Baker |first2=Kathleen M. |year=1992 |title=The changing geography of Africa and the Middle East |publisher=Routledge |isbn=978-0-203-03450-7}} *{{cite book |author1=Caterina Batello|author2=Marzio Marzot|author3=Adamou Harouna Touré|title=The Future is an Ancient Lake|publisher=FAO Interdepartmental Working Group on Biological Diversity for Food and Agriculture|url=https://www.fao.org/3/y5118e/y5118e00.htm|year=2004|isbn=92-5-105064-3}}
==External links== {{Commons and category|linktext=Lake Chad}} *[http://www.cblt.org/en/ Lake Chad Basin Commission] *[https://en.unesco.org/biopalt BIOsphere and Heritage of Lake Chad (BIOPALT) project] *[https://www.earthobservatory.nasa.gov/images/91291/the-ups-and-downs-of-lake-chad The Ups and Downs of Lake Chad] *{{usurped|1=[https://web.archive.org/web/20030926043012/http://www.worldlakes.org/lakedetails.asp?lakeid=8357 Lake Chad in worldlakes.org]}} *[https://wldb.ilec.or.jp/Lake/AFR-02 Lake Chad in World Lake Database] *[https://news.un.org/en/tags/lake-chad Lake Chad {{!}} UN News]
{{Lakes of Chad}} {{Authority control}}
{{DEFAULTSORT:Chad, Lake}} [[Category:Lake Chad| ]] [[Category:Endorheic lakes of Africa]] [[Category:Shrunken lakes]] [[Category:Lakes of Chad]] [[Category:Lakes of Niger]] [[Category:Lakes of Nigeria]] [[Category:Lakes of Cameroon]] [[Category:Flooded grasslands and savannas]] [[Category:Ecoregions of Africa]] [[Category:Geography of Central Africa|Lake Chad]] [[Category:Border tripoints]] [[Category:Chad–Niger border]] [[Category:Chad–Nigeria border]] [[Category:Niger–Nigeria border]] [[Category:Cameroon–Chad border]] [[Category:Cameroon–Nigeria border]] [[Category:Important Bird Areas of Chad]] [[Category:Ramsar sites in Chad]] [[Category:Ramsar sites in Cameroon]] [[Category:Ramsar sites in Niger]] [[Category:Ramsar sites in Nigeria]] [[Category:International lakes of Africa]] [[Category:Lakes of Africa]]