Kalahari Desert

Kalahari
Desert
A satellite image of the Kalahari by NASA World Wind
Country  Botswana  Namibia  South Africa
Landmarks Botswana's Gemsbok National Park, Central Kalahari Game Reserve, Chobe National Park, Kalahari Basin, Kalahari Gemsbok National Park, Kgalagadi Transfrontier Park, Makgadikgadi Pans
River Orange River
Highest point Brandberg Mountain 8,550 ft (2,610 m)
 - coordinates 21°07′S 14°33′E / 21.117°S 14.550°E / -21.117; 14.550
Length 4,000 km (2,485 mi), E/W
Area 930,000 km2 (359,075 sq mi)
Biome Semi-arid desert
The Kalahari Desert (shown in maroon) & Kalahari Basin (orange)
Kalahari in Namibia

The Kalahari Desert is a large semi-arid sandy savanna in southern Africa extending 900,000 square kilometres (350,000 sq mi), covering much of Botswana, parts of Namibia (known as South-West Africa from 1894 to 1990), and regions of South Africa. A semi-desert, with huge tracts of excellent grazing after good rains, the Kalahari supports more animals and plants than a true desert, such as the Namib Desert to the west. There are small amounts of rainfall and the summer temperature is very high. The driest areas usually receive 110–200 millimetres (4.3–7.9 in) of rain per year,[1] and the wettest just a little over 500 millimetres (20 in). The surrounding Kalahari Basin covers over 2,500,000 square kilometres (970,000 sq mi) extending further into Botswana, Namibia and South Africa, and encroaching into parts of Angola, Zambia and Zimbabwe. The Kalahari is home to many migratory birds and animals. Previously havens for wild animals from elephants to giraffes, and for predators such as lions and cheetahs, the riverbeds are now mostly grazing spots, though leopards and cheetahs can still be found. The area is now heavily grazed and cattle fences restrict the movement of wildlife. Among deserts of the Southern Hemisphere, the Kalahari most closely resembles some Australian deserts in its latitude and its mode of formation. The Kalahari Desert came into existence approximately sixty million years ago along with the formation of the African continent.

Description

Derived from the Tswana word Kgala, meaning "the great thirst", or Kgalagadi, meaning "a waterless place",[1] the Kalahari has vast areas covered by red sand without any permanent surface water. Drainage is by dry valleys, seasonally inundated pans, and the large salt pans of the Makgadikgadi Pan in Botswana and Etosha Pan in Namibia. The only permanent river, the Okavango, flows into a delta in the northwest, forming marshes that are rich in wildlife. Ancient dry riverbeds—called omuramba—traverse the central northern reaches of the Kalahari and provide standing pools of water during the rainy season.

Vegetation and flora

Despite its aridity, the Kalahari supports a variety of flora. The native flora includes acacia trees and many other herbs and grasses.[2] The kiwano fruit, also known as the horned melon, melano, African horned cucumber, jelly melon, or hedged gourd, is endemic to a region in the Kalahari Desert (specific region unknown).[3]

Even where the Kalahari "desert" is dry enough to qualify as a desert in the sense of having low precipitation, it is not strictly speaking a desert because it has too dense a ground cover. The main region that lacks ground cover is in the southwest Kalahari (southeast of Namibia, northwest of South Africa and southwest of Botswana) in the south of the Kgalagadi Transfrontier Park. For instance in the ZF Mgcawu District Municipality of South Africa, total vegetation cover may be as low as 30.72% on non-protected (from cattle grazing) farmlands south of Twee Rivieren Rest Camp and 37.74% in the protected (from cattle grazing) South African side of the Kgalagadi Transfrontier Park:[4] these southernmost Kalahari xeric savanna areas are truly semi-deserts. However, in all the remaining Kalahari, except on salt pans during the dry season, the vegetation cover can be clearly denser, up to almost 100% in some limited areas.

In an area of about 600,000 km2 in the south and west of the Kalahari, the vegetation is mainly xeric savanna. This area is the ecoregion identified by World Wide Fund for Nature as Kalahari xeric savanna AT1309. Typical savanna grasses include (Schmidtia, Stipagrostis, Aristida, and Eragrostis) interspersed with trees such as camelthorn (Acacia erioloba), grey camelthorn (Acacia haematoxylon), shepherd’s tree (Boscia albitrunca), blackthorn (Acacia mellifera), and silver cluster-leaf (Terminalia sericea).

In certain areas where the climate is drier, it becomes a true semi-desert with ground not entirely covered by vegetation: "open" as opposed to "closed" vegetation. Examples include the north of the Siyanda District, itself in the north of South Africa, and the Keetmanshoop Rural in the southeast of Namibia. In the north and east, there are dry forests covering an area of over 300,000 km2 in which Rhodesian teak and several species of acacia are prominent. These regions are termed Kalahari Acacia-Baikiaea woodlands AT0709.[5]

Outside the Kalahari "desert", but in the Kalahari basin, a halophytic vegetation to the north is adapted to pans, lakes that are completely dry during the dry season, and maybe for years during droughts, such as in Etosha (Etosha Pan halophytics AT0902) and Makgadikgadi (Zambezian halophytics AT0908).[5]

A totally different vegetation is adapted to the perennial fresh water of the Okavango Delta, an ecoregion termed (Zambezian flooded grasslands AT0907).[5]

Climate

North and east, approximately where the dry forests, savannahs and salt lakes prevail, the climate is sub-humid rather than semi-arid. South and west, where the vegetation is predominantly xeric savanna or even a semi-desert, the climate is "Kalaharian" semi-arid. The Kalaharian climate is subtropical (average annual temperature greater than or equal to 18 °C, with mean monthly temperature of the coldest month strictly below 18 °C), and is semi-arid with the dry season during the "cold" season, the coldest six months of the year. It is the southern tropical equivalent of the Sahelian climate. The altitude has been adduced as the explanation why the Kalaharian climate is not tropical; its altitude ranges from 600 to 1600 meters (and generally from 800 to 1200 meters), resulting in a cooler climate than that of the Sahel or Sahara. For example, winter frost is common from June to August, something rarely seen in the warmer Sahelian regions.[6] For the same reason, summer temperatures certainly can be very hot, but not in comparison to regions of low altitude in the Sahel or Sahara, where some stations record average temperatures of the warmest month around 38 °C, whereas the average temperature of the warmest month in any region in the Kalahari never exceeds 29 °C, though daily temperatures occasionally reach up to close to 45 °C (113 °F) (44.8 °C at Twee Rivieren Rest Camp in 2012).[7]

As in the Sahel, the wet season in the Kalahari is during the six coldest months of the year.

The dry season lasts eight months or more, and the wet season typically from less than one month to four months, depending on location. The southwestern Kalahari is the driest area, in particular a small region located towards the west-southwest of Tsaraxaibis (Southeast of Namibia). The average annual rainfall ranging from around 110 mm (close to aridity) to more than 500 mm in some areas of the north and east. In the driest and sunniest parts of the Kalahari, over 4,000 hours of sunshine are recorded annually on average.

In the Kalahari, there are two main mechanisms of atmospheric circulation, dominated by the Kalahari High anticyclone:[8]

There are huge subterranean water reserves beneath parts of the Kalahari; the Dragon's Breath Cave for example is the largest documented non-subglacial underground lake on the planet. Such reserves may be in part the residues of ancient lakes; the Kalahari Desert was once a much wetter place. The ancient Lake Makgadikgadi dominated the area, covering the Makgadikgadi Pan and surrounding areas, but it drained or dried out some 10,000 years ago. It may have once covered as much as 275,000 square kilometres (106,000 sq mi).

Fauna

Although there are few endemic species, a wide variety of animals are found in the Kalahari including large predators such as the Katanga lion (Panthera leo bleyenberghi), the Transvaal lion (Panthera leo krugeri), South African cheetah (Acinonyx jubatus jubatus), African leopard (Panthera pardus pardus), spotted hyena (Crocuta crocuta), brown hyena (Hyaena brunnea), and Cape wild dog (Lycaon pictus pictus). Birds of prey include the secretary bird (Sagittarius serpentarius), martial eagle (Polemaetus bellicosus) and other eagles, the giant eagle owl (Bubo lacteus) and other owls, falcons, goshawks, kestrels, and kites. Other animals include wildebeest, springbok and other antelopes, porcupines (Hystrix africaeaustralis) and ostriches.[9]

Some of the areas within the Kalahari are seasonal wetlands, such as the Makgadikgadi Pans of Botswana. This area, for example, supports numerous halophilic species, and in the rainy season, tens of thousands of flamingos visit these pans.[10]

Threats and preservation

A meerkat in the Kalahari
The endangered African wild dog in CKGR

The Kalahari has a number of game reserves—Tswalu Kalahari, Southern Africa's largest private game reserve, the Central Kalahari Game Reserve (the world's second largest wildlife park), Khutse Game Reserve and the Kgalagadi Transfrontier Park. Animals that live in the region include brown hyenas, the Kalahari lion, meerkats, giraffes, common warthogs, jackals, chacma baboons, and several species of antelope (including the eland, gemsbok, springbok, hartebeest, steenbok, kudu, and duiker), and many species of birds and reptiles. Camel rides flourish when it rains.

The biggest threat to wildlife are the fences erected to manage herds of grazing cattle, a practice which also removes the plant cover of the savanna itself. Cattle ranchers will also poison or hunt down predators from the rangeland, particularly targeting jackals and wild dogs.

Population

The San people have lived in the Kalahari for 20,000 years as hunter-gatherers.[11] They hunt wild game with bows and poison arrows and gather edible plants, such as berries, melons and nuts, as well as insects. The San get most of their water requirements from plant roots and desert melons found on or under the desert floor. They often store water in the blown-out shells of ostrich eggs. The San live in huts built from local materials—the frame is made of branches, and the roof is thatched with long grass. The Bantu-speaking Tswana, Kgalagadi, and Herero and a small number of European settlers also live in the Kalahari desert. The city Windhoek is situated in the Kalahari Basin.

Kalahari, San and diamonds

In 1996, De Beers evaluated the potential of diamond mining at Gope. In 1997, the eviction of the San and Bakgalagadi tribes in the Central Kalahari Game Reserve from their land began.[12] In 2006, a Botswana High Court ruled in favor of the San and Bakgalagadi tribes in the Central Kalahari Game Reserve, claiming their eviction from the reserve was unlawful. The Government of Botswana granted a permit to De Beers' Gem Diamonds/Gope Exploration Company (Pty) Ltd. to conduct mining activities within the reserve.[13]

Settlements within the Kalahari

Botswana

Namibia

South Africa

In popular culture

References

  1. 1 2 "The Kalahari-Basin". 15 July 2010. Archived from the original on 25 July 2015.
  2. ↑ Martin Leipold, Plants of the Kalahari
  3. ↑ WikiHow, ' Kiwano Fruit
  4. ↑ Wasiolka, Bernd; Blaum, Niels (2011). "Comparing biodiversity between protected savanna and adjacent non-protected farmland in the southern Kalahari". Journal of Arid Environments 75 (9): 836–841 [Table 2 on p. 838]. doi:10.1016/j.jaridenv.2011.04.011.
  5. 1 2 3
  6. ↑ (French) Les milieux désertiques, Jean Demangeot, Edmond Bernus, 2001. Editor: Armand Colin. ISBN 9782200251970, page 20 in particular.
  7. ↑ http://www.mherrera.org/records.htm
  8. ↑ (French) Tropicalité Jean Demangeot Géographie physique intertropicale, pages 44–45, Figure 19, source: Leroux 1989
  9. ↑ http://worldwildlife.org/ecoregions/at1309
  10. ↑ C. Michael Hogan (2008) Makgadikgadi, Megalithic Portal, ed. A.Burnham
  11. ↑ Marshall, Leon (16 April 2003), "Bushmen Driven From Ancestral Lands in Botswana", National Geographic News (Johannesburg), retrieved 2009-04-22
  12. ↑ Workman, James (2009). Heart of Dryness. Walker Publishing. p. 323.
  13. ↑ "UN report condemns Botswana's treatment of Bushmen". Survival for Tribal Peoples. 3 March 2010. Retrieved 31 March 2013.
  14. ↑ ""The Lost World of the Kalahari" (1956)". IMDb. Retrieved 8 January 2013.

Further reading

External links

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Coordinates: 23°S 22°E / 23°S 22°E / -23; 22

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