Lake Chad: general facts

Lake Chad (in French Lac Tchad) is a historically large, shallow lake in Africa, whose size has varied over the centuries. According to the UN it shrank as much as by 95 percent from about 1963 to 1998^[5] yet they also state that "The 2007 (satellite) image shows significant improvement over previous years". Lake Chad is economically important, providing water to more than 20 million people living in the four countries that surround it (Chad, Cameroon, Niger, and Nigeria) on the edge of the Sahara Desert.

Location and description

Lake Chad is located mainly in the far west of Chad, bordering on northeastern Nigeria. TheChari River, fed by its tributary the Logone provides over 90 percent of Lake Chad's water, with a small amount coming from the Yobe River in Nigeria/Niger. Despite high levels of evaporation the lake is still freshwater. Over half of the lake's area is taken up by its many small islands, reedbeds and mudbanks, and a belt of swampland across the middle divides the northern and southern halves while the shorelines are largely composed of marshes.

Because Lake Chad is very shallow—only 10.5 metres (34 ft) at its deepest—its area is particularly sensitive to small changes in average depth, and consequently it also shows seasonal fluctuations in size of about 1m every year. Lake Chad has no apparent outlet, but its waters percolate into the Soro and Bodélé depressions. The climate is dry most of the year round with occasional rains from June to October.

[edit]History

Lake Chad in a 2001 satellite image, with the actual lake in blue, and vegetation on top of the old lake bed in green. Above that, the changes from 1973 to 1997 are shown.

Lake Chad gave its name to the country of Chad. The name Chad is a local word meaning "large expanse of water," in other words, a "lake."^[6]

Lake Chad is believed to be a remnant of a former inland sea which has grown and shrunk with changes in climate over the past 13,000 years. At its largest, around 4000 BC, this lake is estimated to have covered an area of 400,000 km², (approx. 154,000 sq miles). Lake sediments appear to indicate dry periods, when the lake nearly dried up, around 8500 BC, 5500 BC, 2000 BC, and 100 BC."^[7]

It was considered to be one of the largest lakes in the world when first surveyed. It was first surveyed by Europeans in 1823.^[8] Lake Chad has shrunk considerably since the 1960s when it had an area of more than 26,000 km², 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.^[9]

The size of Lake Chad greatly varies seasonally with the flooding of the wetlands areas. In 1983, Lake Chad was reported to have covered 10,000 km²-25,000 km² (3,861 mi²-9652 mi²) ^[2][3], had a maximum depth of 36 feet^[2][3], and a volume of 72 km³ (17.27 mi³)^[2][3].

By 2000 its extent had fallen to less than 1,500 km². 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.^[10] According to CNN senior producer, A. Chris Gajilan, "the United Nations Environment Programme says that about half of the lake's decrease is attributable to human water use such as inefficient damming and irrigation methods. The other half of the shrinkage is due to shifting climate patterns. Anada Tiega of the Lake Chad Basin Commissionblames climate change for 50 to 75 percent of the water's disappearance."^[11] Some consider it likely that the lake will shrink further and perhaps even disappear in the course of the 21st century.

Many areas of Lake Chad are wetlands^[12]. 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. A wetland is an area of land whose soil is saturated with moisture either permanently or seasonally. Such areas may also be covered partially or completely by shallow pools of water.^[13] Wetlands include swamps, marshes, and bogs, among others.

Lake Chad, volume of 72 km³^[2][3], is very small relative to Lake Tanganyika (18,900 km³) and Lake Victoria (2,750 km³) which are African lakes with similar surface areas.

Photography taken by Apollo 7, October 1968.

Map of the lake in 1973

Lake Chad in 1930. Aerial photograph by Walter Mittelholzer.

The lake presently has an average depth of only 1.5 metres (4.9 ft).^{[citation needed]} It nearly dried out in 1908^{[citation needed]} and again in 1984. As it retreats every summer, recessional agriculture is practised, while the Buduma people fish from canoes.

[edit]Flora

The lake is home to more than 44 species of algae and has large areas of swamp and reedbeds. The floodplains on the southern lakeshore are covered in Yaéré grassland of Echinochloa pyramidalis, Vetiveria nigritana, Oryza longistaminata, and Hyparrhenia rufa.

[edit]Fauna

There are many floating islands in the lake. It is home to a wide variety of wildlife, including hippopotamus,crocodile (both in decline here), and large communities of migrating birds including wintering ducks, Ruff(Philomachus pugnax) and other waterfowl, and shore birds. There are two near-endemic birds River Prinia(Prinia fluviatilis) and the Rusty Lark (Mirafra rufa). The shrinking of the lake is threatening nesting sites of the Black Crowned Crane (Balearica pavonina pavonina). During the wet season fish move into the mineral rich lake to breed and find food.

[edit]Threats and preservation

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.^[14] Due to human population expansion and unsustainable human water extraction from Lake Chad, a number of natural species are stressed and threatened from declining Lake levels. For example decline or disappearance of theendangered Painted Hunting Dog, Lycaon pictus has been noted in the Lake Chad area.^[15]

The shrinking of the lake has also caused several different conflicts to emerge as to which country that borders Lake Chad has the rights to the remaining water. Along with the conflicts that involve the countries, violence is increasing between the lake's dwellers. Farmers and herders want the water for their crops and livestock and are constantly diverting the water. The fishermen however want the remaining water in the lake to stay so they can continue to fish and not have to worry about the lake shrinking more and decreasing their already strained supply of fish. Furthermore the birds and animals in the area are threatened as they are important sources of food for the local human population.

The only protected area is 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 site of international importance.

[edit]Diversion proposal

In the 1960s, a plan was proposed to divert the Ubangi River into Lake Chad. 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 Sahelians. Inter-basin water transfer schemes were proposed in the 1980s and 1990s by Nigerian engineer J. Umolu (ZCN Scheme) and Italian firm Bonifica (Transaqua Scheme).^{[16][17][18][19][20]} 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.^[21] In April, 2008, the LCBC advertised a request for proposals for a World Bank-funded feasibility study.