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{{Short description|Lake in Central Africa}}
{{Short description|Lake in Central Africa}}

{{About|the lake in Africa|the lake in Antarctica|Lake Chad (Antarctica)}}
{{About|the lake in Africa|the lake in Antarctica|Lake Chad (Antarctica)}}
{{Use dmy dates|date=September 2020}}
{{Use dmy dates|date=September 2020}}
{{Infobox body of water
{{Infobox body of water
| name = Lake Chad
| name = Lake Chad
| image = Lake Chad from Apollo 7.jpg
| native_name =
| native_name_lang =
| caption = Photograph taken by [[Apollo 7]], October 1968
| other_name = {{plainlist|
| image_bathymetry = Lakechad map.png
*{{native name|kr|Sádǝ}}
| caption_bathymetry = Lake Chad and surrounding region, 2006 map
*{{native name|fr|Lac Tchad}}
| coords = {{Coord|13|0|N|14|30|E|type:waterbody|display=inline,title}}
}}
| lake_type = [[Endorheic]]
| image = Lake Chad satellite.jpg
| location = [[Sahel|Sahelian zone]] at the conjunction of [[Chad]], [[Cameroon]], [[Nigeria]] and [[Niger]]
| coordinates = <!-- {{coord|DD|MM|SS|N|DD|MM|SS|W|region:ZZ_type:waterbody|display =inline,title}} -->
| inflow = [[Chari River]]
| inflow = [[Chari River]]
| rivers =
| outflow = [[Soro Depression|Soro]] and [[Bodélé Depression|Bodélé]] depressions
| catchment =
| outflow = El-Béid and Yedseram rivers
| catchment = <!-- {{convert|VALUE|UNITS}} must be used -->
| basin_countries = [[Chad]], [[Cameroon]], [[Niger]], [[Nigeria]]
| basin_countries = {{TCD}}、{{CMR}}、{{NGA}}、{{NER}}、{{CAF}}、{{SDN}}
| extra = {{Designation list
| designation =
| embed = yes
| length = <!-- {{convert|VALUE|UNITS}} must be used -->
| designation1 = Ramsar
| width = <!-- {{convert|VALUE|UNITS}} must be used -->
| designation1_offname = Lac Tchad
| area = {{convert|2000 |km2|sqmi|abbr=on}}
| designation1_date = 17 June 2001
| max-depth = {{convert|2|m|ft|abbr=on}}
| 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}}</ref>
| volume = <!-- {{convert|VALUE|UNITS}} must be used -->
| designation2 = Ramsar
| salinity =
| designation2_offname = Partie tchadienne du lac Tchad
| temperature_high = <!-- {{convert|VALUE|UNITS}} must be used -->
| designation2_date = 14 August 2001
| temperature_low = <!-- {{convert|VALUE|UNITS}} must be used -->
| 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}}</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}}</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}}</ref>}}
| length =
| width =
| area = {{convert|1540|km2|mi2|abbr=on}} (2020){{sfn|Odada|Oyebande|Oguntola|2005|p=}}
| depth = {{convert|1.5|m|abbr=on}}{{sfn|WaterNews|2008|p=}}
| max-depth = {{convert|11|m|abbr=on}}{{sfn|World Lakes Database|1983|p=}}
| volume = {{convert|6.3|km3|mi3|abbr=on}}{{sfn|World Lakes Database|1983|p=}}
| shore = {{convert|650|km|abbr=on}}{{Citation needed|date=January 2008}}
| elevation = {{convert|278|to|286|m|ft}}
| islands =
| islands =
| cities = <!-- Map -->
| sections =
| pushpin_map = Chad#Cameroon#Niger#Nigeria#Africa
| trenches =
| benches =
| pushpin_label_position =
| cities = {{Plainlist}}
| pushpin_map_alt = Location of Lake Chad in Chad.
* [[Bol, Chad|Bol]], Chad
| pushpin_map_caption = <!-- Below -->
* [[Abadam]], Nigeria
* [[Baga, Borno|Baga]], Nigeria
* [[N'guigmi]], Niger
* [[Bosso, Niger|Bosso]], Niger
* [[Makary, Cameroon|Makary]], Cameroon
{{Endplainlist}}
<!-- Map -->| pushpin_map = Africa
| pushpin_label_position = <!-- left, right, top or bottom -->
| pushpin_map_alt =
| pushpin_map_caption =
| website =
| website =
| reference = {{sfn|Odada|Oyebande|Oguntola|2005|p=}}
| reference =
}}
}}
'''Lake Chad''' ([[Kanuri language|Kanuri]]: ''Sádǝ'', {{Lang-fr|Lac Tchad}}) is a freshwater lake located at the junction of [[Nigeria]], [[Niger]], [[Chad]] and [[Cameroon]] in central and western Africa. It is also an important wetland ecosystem in West Africa. The catchment area of Lake Chad is 1 million square kilometers. It used to be a large lake with an area of 28,000 square kilometers in the 19th century. However, due to climate change and human water diversion, Lake Chad has been greatly reduced since the mid-1970s, and its area has fluctuated between 2,000 and 5,000 square kilometers.
'''Lake Chad''' ({{lang-fr|Lac Tchad}}) is a historically large, shallow, [[endorheic lake]] in [[Central Africa]], which has varied in size over the centuries. According to the ''Global Resource Information Database'' of the [[United Nations Environment Programme]], it shrank by as much as 95% from about 1963 to 1998.<ref>{{cite web|title=Remnants of Chad Lake, Chad, February 2015 {{!}} GRID-Arendal|url=https://www.grida.no/resources/4832|access-date=2021-06-14|website=www.grida.no}}</ref> The lowest area was in 1986, at {{convert|279|km2|abbr=on}},<ref>Umar, I.A., (2018): ''Modelling of water cycle regime of Lake Chad using GIS and remote sensing for decadal periods.'' Unpublished BSc Project. University of Maiduguri, Borno, Nigeria</ref> but "the 2007 (satellite) image shows significant improvement over previous years."{{sfn|United Nations|2007}} Lake Chad is economically important, providing [[water]] to more than 30 million people living in the four countries surrounding it ([[Chad]], [[Cameroon]], [[Niger]], and [[Nigeria]]) on the central part of the [[Sahel]].{{sfn|AllAfrica|2012}} It is the largest lake in the [[Chad Basin]].

==Geography and hydrology==
The freshwater lake is located in the [[Sahel|Sahelian zone]] of West-central Africa. It is located in the interior basin which used to be occupied by a much larger ancient body of water sometimes called by scientists lake Mega Chad<ref>{{cite web|title=Remnants of an Ancient Lake |url=https://earthobservatory.nasa.gov/images/146304/remnants-of-an-ancient-lake|access-date=2023-09-11|website=earthobservatory.nasa.gov}}</ref>. The lake is historically ranked as one of the largest lakes in Africa. Its surface area varies by season as well as from year to year. Lake Chad is mainly in the far west of Chad, bordering on northeastern Nigeria.

The [[Chari River]], fed by its tributary the [[Logone River|Logone]], flowing from the South along the Cameroon border, provides over 90% of the lake's water, with a small amount coming from the [[Yobe River]] in Nigeria/Niger. Despite high levels of evaporation, the lake is [[fresh water]]. Over half of the lake's area is taken up by its many small [[islands]] (including the [[Bogomerom Archipelago]]), reedbeds and mud [[Bank (geography)|banks]], and a belt of [[swampland]] across the middle divides the northern and southern halves. The shorelines are largely composed of [[marshes]]. The [[Lake Chad flooded savanna]]s surround the lake, including permanently and seasonally-flooded grasslands, savannas, and woodlands.

Lake Chad has the [[Bahr el-Ghazal (wadi in Chad)|Bahr el-Ghazal]] outlet, but its waters [[percolate]] into the [[Soro Depression|Soro]] and [[Bodélé Depression|Bodélé]] depressions. The climate is dry most of the year, with moderate rainfall from June through September.

Because Lake Chad is very shallow—only {{convert|10.5|m|ft|0}} at its deepest—its area is particularly sensitive to small changes in average depth, and consequently it also shows seasonal fluctuations in size.

==Etymology==
Lake Chad gave its name to the country of Chad. The name ''Chad'' is said to be derived from the [[Kanuri language|Kanuri]] word ''sádǝ'', said to mean "large expanse of water",{{sfn|Room|1994|p=}} however, the Kanuri dictionary by Norbert Cyffer <ref>[https://archive.org/details/englishkanuridic00cyff/page/n9/mode/2up English–Kanuri Dictionary, Norbert Cyffer]</ref> implies that this may simply be a phonetic derivation of the name ''Chad'' since no such word exists in the Kanuri language that explicitly means "lake" or "large body of water", as the Kanuri words ''kùlúwù'' (lake, river)<ref>[https://wold.clld.org/word/73101856110439834 Kanuri Wordlist, Kùlúwù]</ref> and ''njîkúra'' (sea, ocean)<ref>[https://wold.clld.org/word/73101856262835774 Kanuri Wordlist, Njîkúrà]</ref> bear no resemblance.


==History==
==History==
[[File:Megatschad GIS.PNG|thumb|right|275px|Lake Chad]]
The lake is the remnant of a former [[Inland sea (geology)|inland sea]], paleolake Mega-Chad, which existed during the [[African humid period]]. At its largest, sometime before 5000 BC, Lake Mega-Chad was the largest of four Saharan paleolakes, and is estimated to have covered an area of {{convert|1000000|km2|sqmi|abbr=on}}, larger than the [[Caspian Sea]] is today, and may have extended as far northeast as within {{convert|100|km|mi|abbr=on}} of [[Faya-Largeau]].{{sfn|Drake|Bristow|2006|pp=901, 910}}{{sfn|Stewart|2009|loc=Chapter: Dead and dying seas}} At its largest extent the river [[Mayo Kébbi]] represented the outlet of the paleolake Mega-Chad, connecting it to the [[Niger River]] and the Atlantic.<ref>Leblanc et al. (2006). "Reconstruction of megalake Chad using shuttle radar topographic mission data". ''Palaeogeography, palaeoclimatology, palaeoecology'' 239, pp. 16–27 {{ISSN|0031-0182}} 1872-616X</ref> This lowest point on the basin's rim now stands at about 320 meters above sea level, meaning that even if Lake Chad were to refill to its largest extent it would still be at the most only about 50 meters deep. The presence of [[African manatee]]s in the inflows of Lake Chad is an evidence of the overflow history, since the manatee is otherwise only in rivers connected to the Atlantic Ocean (i.e. it is not possible that it evolved separately in an enclosed Chad Basin). The grand scale of the Mayo Kébbi river course is also evidence of earlier overflow from Mega-Chad; the upstream catchment of today is far too small to have dug such a large channel.
The [[Chad Basin]] was formed by the depression of the [[African Shield]]. The Chad Lake located in the center of the basin is the remnant of the [[Quaternary]] ancient Chad Sea.<ref name=w2/><ref name=hd3/><ref name=r4/> Its area experienced four heydays between 39,000 BC and 300 BC, leaving thick [[diatomaceous earth]] and [[lacustrine deposits]] in the strata.<ref name=w2/> The largest area in history is about 340,400 square kilometers, the volume is about 13,500 cubic kilometers, the maximum depth is about 160 meters, and the lake is about 325 meters above sea level. It flows into the [[Benue River]] through the [[Mayo Kébbi]], and finally flows 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|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>


The Chad Basin contains the earliest evidence of ancient human habitation found so far in West Africa. The Lake Chad area was settled as early as 500 BC, and major archaeological discoveries include the [[Sao civilization]].<ref name=w2/> According to the records of [[Claudius Ptolemy]], the Roman general Septimius Flaccus led an expedition to the Sahara Desert in 50 AD, crossed the [[Tibesti Mountains]], and reached the north of Lake Chad, known as "Hippo and Rhino Lake". The merchant Julius Maternus led an expedition through the same route around 83 AD and brought a rhino back to Rome from Lake Chad.<ref>{{cite book |author1=Joshua J. Mark |title=Roman Expeditions in Sub-Saharan Africa |url=https://www.worldhistory.org/article/1496/roman-expeditions-in-sub-saharan-africa/ |publisher=Ancient History Encyclopedia|website=worldhistory.org |access-date=2023-07-08 |date=2020-02-07}}</ref><ref>{{cite book |author1=Arienne King |title=The Roman Empire in West Africa |url=https://www.worldhistory.org/article/1199/the-roman-empire-in-west-africa/ |website=worldhistory.org |access-date=2023-07-08 |publisher=Ancient History Encyclopedia|date=2018-03-07}}</ref>
[[Romans in Sub-Saharan Africa|Romans reached the lake]] in the first century of [[Roman empire|their empire]]. During the time of [[Augustus]], Lake Chad was still a huge lake and two Roman expeditions were performed in order to reach it: Septimius Flaccus and Julius Maternus reached the "lake of hippopotamus<ref>{{Cite journal|last=Johnston|first=H. H.|date=1910-08-01|title=Lake Chad 1|journal=Nature|language=en|volume=84|issue=2130|pages=244–245|doi=10.1038/084244a0|bibcode=1910Natur..84..244J|s2cid=8682184|issn=1476-4687|doi-access=free}}</ref> (as the lake was called by [[Claudius Ptolemaeus]]). They moved from coastal Tripolitania and passed near the [[Tibesti mountains]]. Both expeditions passed through the territory of the [[Garamantes]], and were able to leave a small garrison on the "lake of hippopotamus and rhinoceros" after three months of travel in desert lands.


Kingdoms arose around Lake Chad during the Middle Ages, and the Lake District became a refuge for tribes that refused to assimilate into these kingdoms. Lake Chad is recorded in many Arabic writings from the 9th to the 14th centuries due to the expansion of Islam into sub-Saharan Africa and the increased Arab interest in geographical exploration. 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, and three scientific expeditions to Lake Chad were conducted between 1898 and 1909.<ref name=w2/>
Lake Chad was first surveyed from shore by Europeans in 1823, and it was considered to be one of the largest lakes in the world then.{{sfn|Funk & Wagnalls|1973|}} In 1851, a party including the German explorer [[Heinrich Barth]] carried a boat overland from Tripoli across the Sahara Desert by camel and made the first European waterborne survey.<ref name=kemper>{{cite book |title=Labyrinth of Kingdoms: 10,000 Miles Through Islamic Africa |publisher=W. W. Norton |author=Steve Kemper |year=2012 |isbn=978-0393079661 }}</ref> British expedition leader [[James Richardson (explorer of the Sahara)|James Richardson]] died just days before reaching the lake.


==Geography==
In Winston Churchill's book ''The River War: An Account of the Reconquest of the Sudan'', published in 1899, he specifically mentions the shrinking of Lake Chad. He writes:
[[File:Charirivermap.png|thumb|right|275px|Chari river map]]
Lake Chad is divided into north and south parts by a natural dam, with the bottom of the northern basin at an altitude of 275.3 meters and the bottom of the southern basin at 278.2 meters. When the water level in the south exceeds 279 meters 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 Shali 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 |jstor=823109 |url=https://www.jstor.org/stable/823109 |access-date=2023-06-18 |archive-date=2023-06-18 |archive-url=https://web.archive.org/web/20230618010146/https://www.jstor.org/stable/823109 }}</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 0.5 and 2 meters, that of the northern lake basin is between 0 and 1.8 meters, and that of the eastern archipelago is between 0 and 2 meters.<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}}</ref> The very shallow average depth means the lake's surface area can vary dramatically based on annual rainfall.


The Lake Chad basin covers an area of about 1 million square kilometers, and is injected by the Shari River, Engada River, and Yobe River.<ref name=r4>{{cite encyclopedia |author=文云朝 |title=乍得湖 |editor=中国大百科全书编委会 |encyclopedia=中国大百科全书 |edition=第三版网络版 |location=北京 |publisher=中国大百科全书出版社 |url=https://www.zgbk.com/ecph/words?SiteID=1&ID=563293 |accessdate=2023-06-11 |language=zh-cn}}</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 [[Shari 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%. The part 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 |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/>
<blockquote>Altogether France has enough to occupy her in Central Africa for some time to come: and even when the long task is finished, the conquered regions are not likely to be of great value. They include the desert of the Great Sahara and wide expanses of equally profitless scrub or marsh. Only one important river, the [[Chari River|Shari]], flows through them, and never reaches the sea: and even Lake Chad, into which the Shari flows, appears to be leaking through some subterranean exit, and is rapidly changing from a lake into an immense swamp.<ref>{{cite book|url=http://www.gutenberg.org/ebooks/4943 |title=The River War: An Account of the Reconquest of the Sudan |author=Winston Churchill|date=1902 |access-date=31 May 2017|via=www.gutenberg.org}}</ref></blockquote>[[File:Megachad en disappearance of lake chad.jpg|thumb|left|Shrinking of Lake Chad, for size comparison the outline of the British Isles]][[File:Lake Chad map showing receding water area and level 1972-2007.svg|thumb|left|upright=1.2|Shrinking of Lake Chad from 1972 to 2007]]


The average annual precipitation in the Lake Chad area is 330 mm, with an average annual precipitation of 560 mm on the south bank and about 250 mm on the north bank. The highest temperature in the rainy season is 30°C, and the highest temperature rises to more than 32°C 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 8°C in December and January. April is usually the hottest month of the year, with temperatures occasionally reaching 40°C, the lowest water levels appear in June to July, and the highest water levels in November to December, with surface water temperatures ranging from 19°C to 32°C.<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 |accessdate=2023-06-13 |language=en}}</ref><ref name=r4/>
Lake Chad has shrunk considerably since the 1960s, when its shoreline had an elevation of about {{convert|286|m|ft}} above sea level{{sfn|Drake|Bristow|2006|loc=Figures 1, 10}} and it had an area of more than {{convert|26000|km2|mi2}}, making its surface the fourth largest in Africa. An increased demand on the lake's water from the local population has likely accelerated its shrinkage over the past 40 years.{{sfn|WaterNews|2008|p=}}


==Hydrology==
The size of Lake Chad greatly varies seasonally with the flooding of the wetlands areas. In 1983, Lake Chad was reported to have covered {{convert|10000|to|25000|km2|mi2|abbr=on}},{{sfn|World Lakes Database|1983|p=}} had a maximum depth of 11 metres (36&nbsp;ft),{{sfn|World Lakes Database|1983|p=}} and a volume of {{convert|72|km3|mi3|abbr=on}}.{{sfn|World Lakes Database|1983|p=}}
[[File:Lake Chad.jpg|thumb|right|275px|Lake Chad now]]
The Lake Chad Basin is one of the major river basins most affected by climate change in the world. Small changes in atmospheric circulation will have a great impact on the rainfall in the Lake Chad Basin. In addition, Lake Chad is an inward shallow lake basin.<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 |pages=97–100 |doi=10.1007/s10040-006-0126-0 |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/>


In 1870, the area of Lake Chad was about 28,000 square kilometers. The lake was able to flow out of the Ghazal River 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 Ghazal River 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 2,000 to 5,000 km2 thereafter.<ref name=7g/>
By 2000, its extent had fallen to less than {{convert|1500|km2|mi2|abbr=on}}. A 2001 study published in the ''[[Journal of Geophysical Research]]'' blamed the lake's retreat largely on [[overgrazing]] in the area surrounding the lake, causing [[desertification]] and a decline in vegetation.{{sfn|Coe|Foley|2001|p=|}} The [[United Nations Environment Programme]] and the [[Lake Chad Basin Commission]] concur that at least half of the lake's decrease is attributable to shifting climate patterns. UNEP blames human water use, such as inefficient damming and irrigation methods, for the rest of the shrinkage.{{sfn|CNN|2007|p=}} As late as December 2014, Lake Chad was still sufficient in size and volume such that boats could capsize or sink. The European Space Agency has presented data<ref>{{cite web|title=Lake Chad water extent increase|url=https://www.esa.int/ESA_Multimedia/Images/2013/10/Lake_Chad_water_extent_increase|access-date=2021-02-27|website=www.esa.int|language=en}}</ref> in 2013 showing an actual increase in lake extent of Lake Chad between the years of 1985 to 2011.<ref>{{cite web |title=Lake Chad water extent increase |url=https://www.esa.int/var/esa/storage/images/esa_multimedia/images/2013/10/lake_chad_water_extent_increase/13371177-1-eng-GB/Lake_Chad_water_extent_increase.gif |website=esa.int |access-date=1 July 2022}}</ref>


From June 1966 to January 1973, the area of Lake Chad shrank from 22,772 square kilometers to 15,400 square kilometers,<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|archiveurl=https://web.archive.org/web/20081216142751/http://www.unep.org/dewa/vitalwater/article116.html|archivedate=2008-12-16}}</ref> further shrunk to 4,398 square kilometers in 1975,<ref name=7g/> and only 1,756 square kilometers 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 }}</ref> From 1995 to 1998, it fluctuated within the range of 1,200 to 4,500 square kilometers.<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 |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> The area once reached 5,075 square kilometers in 2000,<ref name=7g/> and the average area from 2013 to 2016 was about 1,876 square kilometers, with the largest area being 2,231 square kilometers in July 2015.<ref>{{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 }}</ref>
Referring to the [[floodplain]] as a lake may be misleading, as less than half of Lake Chad is covered by water through an entire year. The remaining sections are considered [[wetlands]].


==Ecology==
Lake Chad's volume of {{convert|72|km3|mi3|abbr=on}}{{sfn|World Lakes Database|1983|p=}} is very small relative to that of [[Lake Tanganyika]] ({{convert|18900|km3|mi3|abbr=on}}), and [[Lake Victoria]] ({{convert|2750|km3|mi3|abbr=on}}), African lakes with similar surface areas.
[[File:Kanał doprowadzający do jeziora - Jezioro Czad - 001269s.jpg|thumb|275px|Wetland of Lake Chad]]
Part of the Lake 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 8,225 km2.<ref name=tgd1/> What was once relatively dense woodland around Lake Chad, including species such as kapok and ebony, has been converted to open forest with acacias, baobabs, palms, and Indian dates.<ref name=w2/> The wetland plants in the south mainly include papyrus, etc. Reeds mainly grow in the north where the salinity is high, and the floating plant scorpion sometimes covers large areas of open water. Plants such as red papyrus grow on the shores of lakes with long floods in the south.<ref name=tgd1/>


Lake Chad 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 anatididae 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 |accessdate=2023-07-15}}</ref> and more than one million 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> 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/>
==Flora==
The lake is home to more than 44 species of [[algae]]. In particular it is one of the world's major producers of wild [[spirulina (dietary supplement)|spirulina]]<!--Bacteria =/= algae-->. The lake also has large areas of swamp and reedbeds. The floodplains on the southern lakeshore are covered in wetland grasses such as ''[[Echinochloa]] pyramidalis'', ''[[Vetiveria nigritana]]'', ''[[Oryza longistaminata]]'', and ''[[Hyparrhenia rufa]]''.


The entire Lake 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> 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/>
==Fauna==
[[File:Łódź rybaków Kanuri - Jezioro Czad - 001264s.jpg|thumb|[[Kanuri people|Kanuri]] tribal fishermen in 1970s]]
The entire Lake Chad [[Drainage basin|basin]] holds 179 [[fish]] species, of which more than half are shared with the [[Niger River|Niger River Basin]], about half are shared with the [[Nile River Basin]], and about a quarter are shared with the [[Congo River Basin]].{{sfn|Hughes|Hughes|1992|p=}} Lake Chad itself holds 85 fish species.{{sfn|Hughes|Hughes|1992|p=}} Of the 25 [[Endemism|endemics]] in the basin, only ''[[Brycinus]] dageti'' is found in the lake itself,{{sfn|Hughes|Hughes|1992|p=}} and it is perhaps better treated as a dwarf [[subspecies]] of ''Brycinus nurse''.<ref name=FishBase>{{FishBase | genus = Brycinus | species = nurse | month = May | year = 2011}}</ref> This relatively low [[species richness]] and virtual lack of endemic fish species contrasts strongly with other large African lakes, such as [[Lake Victoria|Victoria]], [[Lake Tanganyika|Tanganyika]] and [[Lake Malawi|Malawi]].{{sfn|Nelson|2006|p=}}


==Development==
There are many [[floating island]]s in the lake. It is home to a wide variety of wildlife, including [[African elephants|elephants]], [[hippopotamus]], [[Nile crocodile|crocodile]] (all in decline), and large communities of migrating birds including wintering [[duck]]s, [[Ruff (bird)|ruff]] (''Philomachus pugnax'') and other waterfowl and shore birds. There are two near-endemic birds in the region, the [[river prinia]] (''Prinia fluviatilis'') and the [[rusty lark]] (''Mirafra rufa''). The shrinking of the lake is threatening nesting sites of the [[black crowned crane|black-crowned crane]] (''Balearica pavonina pavonina''). During the wet season, fish move into the mineral-rich lake to breed and find food. Carnivores such as the [[Central African cheetah]] (''Acinonyx jubatus soemmeringii''), the [[striped hyena]] (''Hyaena hyaena'') and the [[caracal]] (''Felis caracal'') used to inhabit areas surrounding the lake.<ref>{{cite web|title=Lake Chad flooded savanna|url=https://www.worldwildlife.org/ecoregions/at0904|publisher=WWF World Wildlife.org|access-date=14 July 2015}}</ref>
[[File:Transaqua.svg|thumb|upright=1.15|275px|Lake Chad replenishment project]]
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 100 people per square kilometer. They rely on the water source of Chad Lake for irrigation, breeding, animal husbandry and drinking.<ref name=4d/> 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 corn, 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/>


At the same time, the conflicts between countries and ethnic groups competing for water and land are also escalating, and the four countries along the lake are all facing the problem of extreme poverty.<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/> Due to the difficulty in meeting their livelihoods, some local residents have been involved in drug and arms trade, and even spawned terrorist organizations such as [[Boko Haram]].<ref name=4d/>
==Threats and preservation==
[[File:An evergreen lake chad shore (detilt).jpg|thumb|right|upright=1.4|Shore of Lake Chad]]
There is some debate over the mechanisms causing the lake's disappearance. The leading theory, which is most often cited by the UN, is that the unsustainable usage of the lake by both governments and local communities has caused the lake to be [[Overdrafting|over-used]], not allowing it to replenish.<ref>{{cite web|url=http://www.unep.org/dewa/vitalwater/article116.html|title=Lake Chad: almost gone|publisher=[[United Nations Environment Programme]] (UNEP)|access-date=5 December 2015|archiveurl=https://web.archive.org/web/20081216142751/http://www.unep.org/dewa/vitalwater/article116.html|archivedate=16 December 2008}}</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 Njanna, 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>{{cite web |title=About us |url=https://cblt.org/about-us/ |website=Lake Chad Basin Commission |accessdate=2023-07-15}}</ref> The surrounding countries' water replenishment plan for Lake Chad includes the construction of a 2,400-kilometer canal to transport 100 billion cubic meters 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}}</ref>
A number of other theories exist, including sea surface temperature changes between the hemispheres or in the Indian Ocean leading to oceanic forcing of rainfall patterns in the Sahel region. Others model anthropogenic sulfate emissions in the later 20th century and conclude that these could also be the cause of rainfall patterns shifting farther south, thereby making the region drier and not allowing the lake to replenish. The implementation of new regulations concerning air pollutants may be responsible for the small increase of the lake size in recent years.<ref>{{cite journal|title=Anthropogenic sulfate aerosol and the southward shift of tropical precipitation in the late 20th century|date=24 April 2013|journal= Geophysical Research Letters|doi=10.1002/grl.50502|last1=Hwang|first1=Yen‐Ting|last2=Frierson|first2=Dargan M. W.|last3=Kang|first3=Sarah M.|volume=40|issue=11|pages=2845–2850|bibcode=2013GeoRL..40.2845H|doi-access=free}}</ref>

The only protected area is the Lake Chad Game Reserve, which covers half of the area next to the lake that belongs to Nigeria. The whole lake has been declared a [[Ramsar Convention|Ramsar site]] of international importance.<ref>{{cite web|url=https://rsis.ramsar.org/ris/1749|title=Lake Chad Wetlands in Nigeria {{!}} Ramsar Sites Information Service|website=rsis.ramsar.org|language=en|access-date=2018-02-03}}</ref>

Speaking at the United Nations 73rd General Assembly, the President of Nigeria urged the international community to assist in combatting the root causes of conflict surrounding the Lake Chad [[Endorheic basin]]. Recent violence in the region has been attributed to competition between farmers and herders seeking irrigation for crops and watering of herds respectively.<ref>{{cite web | url=http://webtv.un.org/search/nigeria-%E2%80%93-president-addresses-general-debate-73rd-session/5839967838001/?term=President%20of%20Nigeria,%20General%20Assembly&sort=date&page=17 | title=UN Live United Nations Web TV - Search Results for "President of Nigeria, General Assembly" - Nigeria – President Addresses General Debate, 73rd Session}}</ref>

In September 2020, in order to explore oil and mining opportunities in the region, [[Patalet Geon|Chad's tourism and culture minister]] wrote to [[UNESCO]], the body which awards the [[World Heritage Site|world heritage designation]], asking to "postpone the process of registering Lake Chad on the world heritage list".<ref name=Guardian>{{cite news | last = Gouby | first = Mélanie | date = 24 September 2020 | title = Chad halts lake's world heritage status request over oil exploration | url = https://www.theguardian.com/world/2020/sep/24/chad-halts-lake-world-heritage-status-request-over-oil-exploration-unesco | newspaper = [[The Guardian]] | access-date = 24 September 2020}}</ref>

===Management===
[[File:Transaqua.svg|thumb|upright=1.15|The Transaqua scheme (in red) to replenish the lake]]
{{Main|Lake Chad replenishment project}}

Plans to divert the [[Ubangi River]] into Lake Chad were proposed in 1929 by [[Herman Sörgel]] in his [[Atlantropa]] project and again in the 1960s. The copious amount of water from the Ubangi would revitalize the dying Lake Chad and provide livelihood in fishing and enhanced agriculture to tens of millions of central Africans and [[Sahel]]ians. Interbasin water transfer schemes were proposed in the 1980s and 1990s by Nigerian engineer J. Umolu (ZCN scheme) and Italian firm Bonifica (the Transaqua canal scheme).{{sfn|Pearce|1991|p=}}{{sfn|Umolu|1990|pp=218–262}}{{sfn|Chapman|Baker|1992|}}{{sfn|Umolu|1994|loc=Section X}}

In 1994, the [[Lake Chad Basin Commission]] (LCBC) proposed a similar project, and at a March 2008 summit, the heads of state of the LCBC member countries committed to the diversion project.{{sfn|Voice of America|2008}} In April 2008, the LCBC advertised a request for proposals for a World Bank-funded feasibility study.<ref>{{cite web|title=Encyclopedia Britannica|url=https://www.britannica.com/|website=Encyclopedia Britannica|language=en|access-date=2020-05-28}}</ref> Neighboring countries have agreed to commit resources to restoring the lake, notably Nigeria.<ref>{{cite web|url=https://www.un.org/africarenewal/magazine/april-2012/africa%E2%80%99s-vanishing-lake-chad|title=Africa's vanishing Lake Chad|access-date=5 December 2015}}</ref><ref>{{cite web|url=http://www.thisdaylive.com/articles/nigeria-contributes-5m-to-restore-receding-lake-chad/176595/|title=Nigeria Contributes $5m to Restore Receding Lake Chad, Articles – THISDAY LIVE|access-date=5 December 2015|url-status=dead|archive-url=https://web.archive.org/web/20140911201524/http://www.thisdaylive.com/articles/nigeria-contributes-5m-to-restore-receding-lake-chad/176595/|archive-date=11 September 2014}}</ref>

The CIMA (Canada) proposed project can be used as an inland [[waterway]], as it uses the same water flow (100&nbsp;m<sup>3</sup>/s) as the [[Moscow Canal]].

===Local impact===
[[File:LakeChadCameroonTown.jpg|thumb|A town on the shores of Lake Chad]]
The dwindling of the lake has had devastating impacts on Nigeria.<ref name="D+C">{{cite news |title=The dwindling lake|url=https://www.dandc.eu/en/article/climate-change-lake-chad-region-affects-several-countries-negatively|author=Damilola Oyedele|work=D+C, development and cooperation |date=11 May 2017 |access-date=14 June 2017}}</ref> Because of the way it has shrunk dramatically in recent decades, the lake has been labeled an [[ecological catastrophe]] by the UN [[Food and Agriculture Organization]].{{sfn|Voice of America|2009}} Human population expansion and unsustainable human water extraction from Lake Chad have caused several natural species to be stressed and threatened by declining lake levels. For example, the decline or disappearance of the [[endangered]] [[Lycaon pictus|painted hunting dog]] has been noted in the Lake Chad area.{{sfn|Hogan|2009|p=}}

The shrinking of the lake has also caused several different [[water conflict|conflicts]] to emerge, as the countries bordering Lake Chad argue over the rights to the remaining areas of water. Along with international conflicts, violence between countries is also increasing among the lake's dwellers. Farmers and herders want the water for their crops and livestock and are constantly diverting the water,<ref>{{cite web|url=https://www.sciencedaily.com/releases/2012/02/120228140537.htm|title=Lake Chad: Inhabitants adapt to lower water levels|website=sciencedaily.com|access-date=31 May 2017}}</ref> while the lake's fishermen want water diversion slowed or halted in order to prevent continuing decline in water levels resulting in further strain on the lake's fish.<ref>{{Cite news|url=http://wwf.panda.org/about_our_earth/about_freshwater/rivers/irbm/cases/lake_chad_river_case_study/|title=Case study on river management: Lake Chad|access-date=2018-02-13|language=en}}</ref> Furthermore, populations of birds and other animals in the area are threatened, including those that serve as important sources of food for the local human population.

== See also ==
{{Portal|Lakes|Earth sciences|Water}}
* [[Lake Ptolemy]], former lake
* [[Aral Sea]], lake that has largely dried up
* ''[[Daphnia barbata]],'' water flea found in Lake Chad
* [[List of drying lakes]]
* [[List of lakes]]
* [[Neolithic Subpluvial]], former African climate period
* The [[Sudd]], an immense marshland in neighboring [[South Sudan]] along the [[Nile]] and [[Bahr el Ghazal River|Bahr-el-Ghazal]]
* [[Nikolay Gumilev]], wrote a poem on Lake Chad


==References==
==References==
{{reflist|20em}}
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*{{cite web |last=Stewart |first=Robert |url=http://oceanworld.tamu.edu/resources/environment-book/dyingseas.html |title=Dustiest places on Earth—dead and dying seas |work=Environmental Science in the 21st Century. A New Online Environmental Science Book for College Students |date=28 July 2009 |access-date=18 August 2011 |archive-url=https://web.archive.org/web/20160430005629/http://oceanworld.tamu.edu/resources/environment-book/dyingseas.html |archive-date=30 April 2016 |url-status=dead }}
*{{Cite journal|last=Umolu |first=Jerome C. |year=1990 |title=Macro Perspectives for Nigeria's Water Resources Planning |journal=Proceedings of the First Biennial National Hydrology Symposium, Maiduguri, Nigeria |pages=218–262 }}
*{{cite web |last=Umolu |first=Jerome C. |year=1994 |url=http://dwb.unl.edu/Teacher/NSF/C09/C09Links/www.ccnet.com/~mcumolu/globclim.html |title=Combating Climate Induced Water And Energy Deficiencies in West Central Africa: hydro/energy interconnections |url-status=dead |archive-url=https://web.archive.org/web/20110526135224/http://dwb.unl.edu/Teacher/NSF/C09/C09Links/www.ccnet.com/~mcumolu/globclim.html |archive-date=26 May 2011 }}
*{{cite web |publisher=[[United Nations Environment Programme]] |year=2007 |url=http://na.unep.net/atlas/webatlas.php?id=58 |title=Atlas of Our Changing Environment |ref={{sfnref|United Nations|2007}} }}
*{{cite web |date=2008-03-28 |url=http://www.voanews.com/content/a-13-2008-03-28-voa33/339868.html |title=African Leaders Team Up to Rescue Lake Chad |publisher=[[Voice of America]] |ref={{sfnref|Voice of America|2008}} |access-date=23 June 2012 |archive-url=https://web.archive.org/web/20160305135305/http://www.voanews.com/content/a-13-2008-03-28-voa33/339868.html |archive-date=5 March 2016 |url-status=dead }}
*{{cite web |date=2009-11-11 |url=http://www.voanews.com/content/a-13-2009-10-16-voa22/414740.html |title=Experts Look For Ways to Save Lake Chad |publisher=Voice of America |ref={{sfnref|Voice of America|2009}} |access-date=23 June 2012 |archive-url=https://web.archive.org/web/20160305135618/http://www.voanews.com/content/a-13-2009-10-16-voa22/414740.html |archive-date=5 March 2016 |url-status=dead }}
*{{cite journal |journal=WaterNews |date=24 June 2008 |title=Vanishing Lake Chad—a water crisis in central Africa |url=http://www.circleofblue.org/waternews/world/vanishing-lake-chad-a-water-crisis-in-central-africa/ |ref={{sfnref|WaterNews|2008}} |access-date=26 December 2018 |archive-url=https://web.archive.org/web/20090502034457/http://www.circleofblue.org/waternews/world/vanishing-lake-chad-a-water-crisis-in-central-africa/ |archive-date=2 May 2009 |url-status=dead }}
*{{cite web |work=World Lakes Database |year=1983 |url=http://www.ilec.or.jp/database/afr/afr-02.html |title=Lake Chad |publisher=International Lake Environment Committee (ILEC) |ref={{sfnref|World Lakes Database|1983}} |url-status=dead |archive-url=https://web.archive.org/web/20100206160207/http://www.ilec.or.jp/database/afr/afr-02.html |archive-date=6 February 2010 }}
{{refend}}

==External links==
{{Commons and category|linktext=Lake Chad}}
*[http://www.ppl.nl/index.php?option=com_wrapper&view=wrapper&Itemid=82 Bibliography on Water Resources and International Law] Peace Palace Library
*[http://www.eoearth.org/article/Lake_Chad_flooded_savanna The Encyclopedia of Earth: Lake Chad flooded savanna]
*[https://web.archive.org/web/20040629170830/http://www.earthtrends.wri.org/maps_spatial/maps_detail_static.cfm?map_select=294&theme=2 Information on, and a map of, Chad's watershed].
*[https://web.archive.org/web/20120813015647/http://www.waterandnature.org/en/resources/publications/thematic-collection/facts-figures/watersheds-world Map of the Lake Chad basin] at Water Resources eAtlas.
*[https://www.theguardian.com/international/story/0,,1695804,00.html Article on the disappearing lake] in ''The Guardian''.
*{{cite journal|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|year= 2006|last1= Leblanc|first1= Marc|last2= Favreau|first2= Guillaume|last3= Maley|first3= Jean|last4= Nazoumou|first4= Yahaya|last5= Leduc|first5= Christian|last6= Stagnitti|first6= Frank|last7= Van Oevelen|first7= Peter J.|last8= Delclaux|first8= François|last9= Lemoalle|first9= Jacques|bibcode= 2006PPP...239...16L}}
*[https://www.patriotdirect.org/lakes-become-deserts-the-story-of-lake-chad/ Lakes become deserts: The story of Lake Chad – patriotdirect.org] {{Webarchive|url=https://web.archive.org/web/20200802231221/https://www.patriotdirect.org/lakes-become-deserts-the-story-of-lake-chad/ |date=2 August 2020 }}


{{Lakes of Chad}}
{{Lakes of Chad}}

Revision as of 16:46, 12 September 2023

This article is about the lake in Africa. For the lake in Antarctica, see Lake Chad (Antarctica).

Lake Chad
Lake Chad is located in Africa
Lake Chad
Lake Chad
LocationSahelian zone at the conjunction of Chad, Cameroon, Nigeria and Niger
Primary inflowsChari River
Primary outflowsEl-Béid and Yedseram rivers
Basin countries Chad、 Cameroon、 Nigeria、 Niger、 Central African Republic、 Sudan
Surface area2,000 km2 (770 sq mi)
Max. depth2 m (6.6 ft)
Settlements

Lake Chad (Kanuri: Sádǝ, French: Lac Tchad) is a freshwater lake located at the junction of Nigeria, Niger, Chad and Cameroon in central and western Africa. It is also an important wetland ecosystem in West Africa. The catchment area of Lake Chad is 1 million square kilometers. It used to be a large lake with an area of 28,000 square kilometers in the 19th century. However, due to climate change and human water diversion, Lake Chad has been greatly reduced since the mid-1970s, and its area has fluctuated between 2,000 and 5,000 square kilometers.

History

Lake Chad

The Chad Basin was formed by the depression of the African Shield. The Chad Lake located in the center of the basin is the remnant of the Quaternary ancient Chad Sea.[1][2][3] Its area experienced four heydays between 39,000 BC and 300 BC, leaving thick diatomaceous earth and lacustrine deposits in the strata.[1] The largest area in history is about 340,400 square kilometers, the volume is about 13,500 cubic kilometers, the maximum depth is about 160 meters, and the lake is about 325 meters above sea level. It flows into the Benue River through the Mayo Kébbi, and finally flows into the Atlantic Ocean through the Niger River.[4]

The Chad Basin contains the earliest evidence of ancient human habitation found so far in West Africa. The Lake Chad area was settled as early as 500 BC, and major archaeological discoveries include the Sao civilization.[1] According to the records of Claudius Ptolemy, the Roman general Septimius Flaccus led an expedition to the Sahara Desert in 50 AD, crossed the Tibesti Mountains, and reached the north of Lake Chad, known as "Hippo and Rhino Lake". The merchant Julius Maternus led an expedition through the same route around 83 AD and brought a rhino back to Rome from Lake Chad.[5][6]

Kingdoms arose around Lake Chad during the Middle Ages, and the Lake District became a refuge for tribes that refused to assimilate into these kingdoms. Lake Chad is recorded in many Arabic writings from the 9th to the 14th centuries due to the expansion of Islam into sub-Saharan Africa and the increased Arab interest in geographical exploration. 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, and three scientific expeditions to Lake Chad were conducted between 1898 and 1909.[1]

Geography

Chari river map

Lake Chad is divided into north and south parts by a natural dam, with the bottom of the northern basin at an altitude of 275.3 meters and the bottom of the southern basin at 278.2 meters. When the water level in the south exceeds 279 meters above sea level, it will flow into the north.[7] In the south, there is continuous open water at the mouth of the Shali River, and the western part of the water is covered by reed swamps,[8] and the sand dunes that are not completely submerged in the eastern waters form an archipelago.[3] The average depth of the southern lake basin is between 0.5 and 2 meters, that of the northern lake basin is between 0 and 1.8 meters, and that of the eastern archipelago is between 0 and 2 meters.[9] The very shallow average depth means the lake's surface area can vary dramatically based on annual rainfall.

The Lake Chad basin covers an area of about 1 million square kilometers, and is injected by the Shari River, Engada River, and Yobe River.[3][1] 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 Shari 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%. The part is only slightly salty.[10][2]

The average annual precipitation in the Lake Chad area is 330 mm, with an average annual precipitation of 560 mm on the south bank and about 250 mm on the north bank. The highest temperature in the rainy season is 30°C, and the highest temperature rises to more than 32°C 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 8°C in December and January. April is usually the hottest month of the year, with temperatures occasionally reaching 40°C, the lowest water levels appear in June to July, and the highest water levels in November to December, with surface water temperatures ranging from 19°C to 32°C.[1][3]

Hydrology

Lake Chad now

The Lake Chad Basin is one of the major river basins most affected by climate change in the world. Small changes in atmospheric circulation will have a great impact on the rainfall in the Lake Chad Basin. In addition, Lake Chad is an inward shallow lake basin.[11][12] 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.[13]

In 1870, the area of Lake Chad was about 28,000 square kilometers. The lake was able to flow out of the Ghazal River 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 Ghazal River again.[1] 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.[11] During this period, Lake Chad shrunk considerably and fluctuated in the range of 2,000 to 5,000 km2 thereafter.[7]

From June 1966 to January 1973, the area of Lake Chad shrank from 22,772 square kilometers to 15,400 square kilometers,[13] further shrunk to 4,398 square kilometers in 1975,[7] and only 1,756 square kilometers in February 1994.[13] Since then, the area of Lake Chad has entered a relatively stable stage with a slight increase.[14] From 1995 to 1998, it fluctuated within the range of 1,200 to 4,500 square kilometers.[7] The area once reached 5,075 square kilometers in 2000,[7] and the average area from 2013 to 2016 was about 1,876 square kilometers, with the largest area being 2,231 square kilometers in July 2015.[15]

Ecology

Wetland of Lake Chad

Part of the Lake 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 8,225 km2.[16] What was once relatively dense woodland around Lake Chad, including species such as kapok and ebony, has been converted to open forest with acacias, baobabs, palms, and Indian dates.[1] The wetland plants in the south mainly include papyrus, etc. Reeds mainly grow in the north where the salinity is high, and the floating plant scorpion sometimes covers large areas of open water. Plants such as red papyrus grow on the shores of lakes with long floods in the south.[16]

Lake Chad is permanently or seasonally inhabited by hundreds of species of birds such as Northern shoveler, Egyptian goose and Marabou stork.[1] It is an important wintering ground for European anatididae and wading birds. There are raptors such as steppe eagle and booted eagle on the lakeshore,[16] and more than one million Ruff can be observed on the lake at one time.[17] 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.[16]

The entire Lake 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.[2] 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.[8]

Development

Lake Chad replenishment project

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 100 people per square kilometer. They rely on the water source of Chad Lake for irrigation, breeding, animal husbandry and drinking.[10] 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 corn, cowpea, rice, sorghum and other crops.[18] 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.[10]

At the same time, the conflicts between countries and ethnic groups competing for water and land are also escalating, and the four countries along the lake are all facing the problem of extreme poverty.[10] 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.[17][2] Due to the difficulty in meeting their livelihoods, some local residents have been involved in drug and arms trade, and even spawned terrorist organizations such as Boko Haram.[10]

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 Njanna, 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.[19] The surrounding countries' water replenishment plan for Lake Chad includes the construction of a 2,400-kilometer canal to transport 100 billion cubic meters 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.[20]

References

  1. ^ a b c d e f g h i Gritzner, J. A. "Lake Chad". Encyclopedia Britannica. Chicago: Encyclopædia Britannica, Inc. Retrieved 13 June 2023.
  2. ^ a b c d Hughes, R. H.; Hughes, J. S. (1992). A Directory of African Wetlands (PDF). IUCN / UNEP / WCMC. pp. 329–330. ISBN 2-88032-949-3. Archived (PDF) from the original on 24 September 2012. Retrieved 14 June 2023.
  3. ^ a b c d 文云朝. "乍得湖". In 中国大百科全书编委会 (ed.). 中国大百科全书 (in Chinese (China)) (第三版网络版 ed.). 北京: 中国大百科全书出版社. Retrieved 11 June 2023.
  4. ^ Leblanc, M.; Favreau, G.; Maley, J.; Nazoumou, Y.; Leduc, C.; Stagnitti, F.; van Oevelen, P. J.; Delclaux, F.; Lemoalle, J. (2006). "Reconstruction of Megalake Chad using Shuttle Radar Topographic Mission data". Palaeogeography, Palaeoclimatology, Palaeoecology. 239 (1–2): 16–27. doi:10.1016/j.palaeo.2006.01.003. Archived from the original on 13 June 2023. Retrieved 13 June 2023.
  5. ^ Joshua J. Mark (7 February 2020). Roman Expeditions in Sub-Saharan Africa. Ancient History Encyclopedia. Retrieved 8 July 2023. {{cite book}}: |website= ignored (help)
  6. ^ Arienne King (7 March 2018). The Roman Empire in West Africa. Ancient History Encyclopedia. Retrieved 8 July 2023. {{cite book}}: |website= ignored (help)
  7. ^ a b c d e 刘甜甜; 刘荣高; 葛全胜 (2013). "基于多源遥感数据的非洲乍得湖水面变化监测". 地理科学进展 (in Chinese (China)). 32 (6): 906–912. doi:10.11820/dlkxjz.2013.06.007.
  8. ^ a b Marie-Thérèse Sarch; Charon Birkett (June 2000). "Fishing and farming at Lake Chad: Responses to lake-level fluctuations". The Geographical Journal. 166 (2): 156–172. JSTOR 823109. Archived from the original on 18 June 2023. Retrieved 18 June 2023.
  9. ^ Jacques Lemoalle; Jean-Claude Bader; Marc Leblanc; Ahmed Sedick (January 2012). "Recent changes in Lake Chad: Observations, simulations and management options (1973–2011)". Global and Planetary Change. 80–81 (247–254): 247–254. doi:10.1016/j.gloplacha.2011.07.004.
  10. ^ a b c d e 袁宣民 (2016). "乍得湖的环境、安全及其脆弱性". 世界科学 (in Chinese (China)) (7): 21–23. Archived from the original on 21 March 2023. Retrieved 13 June 2023.
  11. ^ a b Evans, T. (1996). "The effects of changes in the world hydrological cycle on availability of water resources". In Bazzaz, F.; Sombroek, W. (eds.). Global climate change and agricultural production. FAO / John Wiley & Sons. ISBN 92-5-103987-9. Archived from the original on 18 June 2023.
  12. ^ Leblanc, M.; Favreau, G.; Tweed, S. (2007). "Remote sensing for groundwater modelling in large semiarid areas:Lake Chad Basin,Africa". Hydrogeology Journal. 15: 97–100. doi:10.1007/s10040-006-0126-0.
  13. ^ a b c "Lake Chad: almost gone". United Nations Environment Programme (UNEP). Archived from the original on 16 December 2008. Retrieved 5 December 2015.
  14. ^ Wengbin Zhu; Jiabao Yan; Shaofeng Jia (2017). "Monitoring Recent Fluctuations of the Southern Pool of Lake Chad Using Multiple Remote Sensing Data: Implications for Water Balance Analysis". Remote Sensing. 9 (10): 1032. doi:10.3390/rs9101032.
  15. ^ Willibroad Gabila Buma; Sang-Il Lee; Jae Young Seo (2018). "Recent surface water extent of Lake Chad from multispectral sensors and GRACE". Sensors. 18 (7): 2082. doi:10.3390/s18072082. PMC 6069056. PMID 29958481.
  16. ^ a b c d Emma Martin; Neil Burgess. "Lake Chad Flooded Savanna". www.oneearth.org. Retrieved 15 July 2023.
  17. ^ a b Keith, J. O.; Plowes, D. C. H. (March 1997). Considerations of Wildlife Resources and Land Use in Chad (PDF) (Report). Office of Sustainable Development, Africa Bureau, USAID. p. 3. SD Technical Paper No. 45. Archived from the original (PDF) on 18 June 2023.
  18. ^ Luxereau, A.; Genthon, P.; Ambouta, J.-M. K. (2011). "Fluctuations in the Size of Lake Chad: Consequences on the Livelihoods of the Riverain Peoples in Eastern Niger". Regional Environmental Change. 12 (3): 507–521. doi:10.1007/s10113-011-0267-0. Archived from the original on 14 June 2023. Retrieved 13 June 2023.
  19. ^ "About us". Lake Chad Basin Commission. Retrieved 15 July 2023.
  20. ^ Ross, Will (31 March 2018). "Can the vanishing lake be saved?". BBC. Retrieved 28 January 2019.
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