Kalahari is derived from theTswana wordKgala, meaning "the great thirst", orKgalagadi, meaning "a waterless place";[1] the Kalahari has vast areas covered by red sand without any permanent surface water.
This sectionneeds expansion. You can help byadding to it.(April 2021)
The Kalahari Desert was not always an arid environment. Geological and paleoclimatic evidence suggests that during parts of the late Pleistocene, the region experienced significantly wetter and cooler conditions. Fossil flora and fauna fromGcwihaba Cave in northwestern Botswana indicate that the area supported more abundant vegetation and permanent water sources between roughly30,000 and 11,000 Before Present (BP), with the most humid period occurring after17,500 BP.[2] Sediment cores, pollen records, and fossilized animal remains from other parts of the Kalahari, including theMakgadikgadi Pans andOkavango Basin, corroborate these findings, showing evidence of large paleolakes and river systems that once covered much of what is now desert.[3]
During these wetter phases, the Kalahari likely supported populations of large mammals such as antelopes, elephants, and even hippopotamuses, alongside diverse plant species typical of savanna and woodland biomes. As the global climate shifted toward theHolocene around 11,000 BP, rainfall decreased and evaporation rates rose, leading to the gradual desiccation of the region and the establishment of the semi-arid ecosystem characteristic of the modern Kalahari Desert.[4]
Drainage of the desert is by dry black valleys, seasonally inundated pans, and the largesalt pans of theMakgadikgadi Pan in Botswana andEtosha Pan in Namibia. The only permanent river, theOkavango, flows into adelta in the northwest, forming marshes that are rich in wildlife. Ancient dry riverbeds—calledOuramba—traverse the central northern reaches of the Kalahari and provide standing pools of water during the rainy season.
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 theNamib Desert to the west. There is little rainfall, and the summer temperature is very high. The driest areas usually receive 110–200 mm (4.3–7.9 in) of rain per year,[1] and the wettest just a little over 500 mm (20 in). The surroundingKalahari Basin covers over 2,500,000 km2 (970,000 sq mi) extending farther into Botswana, Namibia, and South Africa, encroaching into parts ofAngola,Zambia andZimbabwe.
The climate is sub-humid rather than semi-arid in the north and east, where the dry forests, savannahs, and salt lakes prevail. South and west, where the vegetation is predominantlyxeric 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 (64 °F), at peaks reaching 40 °C (104 °F) and above, with mean monthly temperature of the coldest month strictly below 18 °C (64 °F), and is semi-arid with the dry season from April to September, the coldest six months of the year. It is the southern tropical equivalent of theSahelian climate with the wet season during summer. 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 theSahel orSahara. For example, winter frost is common from June to August, rarely seen in the warmer Sahelian regions.[2] 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 (100 °F), whereas the average temperature of the warmest month in any region in the Kalahari never exceeds 29 °C (84 °F), though daily temperatures occasionally reach up to close to 45 °C (113 °F) (44.8 °C (112.6 °F) at Twee Rivieren Rest Camp in 2012).[5]
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, particularly a small region toward the west-southwest of Tsaraxaibis (Southeast of Namibia). The average annual rainfall ranges from around 110 mm (close to aridity) to more than 500 mm in some north and east areas. During summertime in all regions, rainfall may go with heavy thunderstorms. 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 three main mechanisms of atmospheric circulation, dominated by theKalahari Highanticyclone[6] in winter, and by the Kalahari Heat Low in summer:[7]
The North and Northwest of the Kalahari are subject to the alternation "Intertropical Convergence Zone (ITCZ)/"ContinentalTrade winds". The ITCZ is the meeting area of the boreal trade winds with their austral counterparts what meteorologists call "Meteorological equator" and the sailors "Doldrum" or "Pot-au-noir" : the ITCZ generates rains in the wet season, whereas the continental trade winds cause the dry season;
The rest of the Kalahari is subject to the maritime trade winds that largely shed their moisture as they cross up and over theSouthern African Great Escarpment before arriving over the Kalahari.
In the southern hemisphere summer (from December to February), a low-pressure system develops over the Kalahari, which is driven by strong surface heating (known as aThermal Low). The low-pressure system helps to control the moisture-bearing easterly wind emanating from theIndian Ocean,[8] thus influencing rainfall across southern Africa.[9]
There are hugesubterranean water reserves beneath parts of the Kalahari; theDragon's Breath Cave, for example, is the largest documented non-subglacial underground lake. Such reserves may partly be the residues of ancient lakes; the Kalahari Desert was once a much wetter place. The ancientLake 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 120,000 square kilometres (46,000 sq mi).[10] In ancient times, there was sufficient moisture for farming, with dikes and dams collecting the water. These are now filled with sediment, breached, or no longer in use, though they can be readily seen via Google Earth.[11]
The Kalahari has had a complex climatic history over the past million or so years, in line with major global changes. Changes in the last 250,000 years have been reconstructed from various data sources, providing evidence of former extensive lakes and drier periods. During the latter, the area of the Kalahari has expanded to include parts of westernZimbabwe,Zambia, andAngola.[12]
Devil's thorn flower (Tribulus zeyheri) growing in the Kalahari DesertCamel thorn scattered ondunes in the Kalahari Desert
Due to its low aridity, the Kalahari supports a variety of flora. The native flora includesacacia trees and many other herbs and grasses.[13] Thekiwano fruit, also known as the horned melon, melano, African horned cucumber, jelly melon, or hedged gourd, isendemic to a region in the Kalahari Desert (specific region unknown).[14]
Even where the Kalahari "desert" is dry enough to qualify as adesert in the sense of having lowprecipitation, 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 theKgalagadi Transfrontier Park. For instance, in theZF Mgcawu District Municipality ofSouth 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:[15] 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 denser, up to almost 100%, in some limited areas.
In certain areas where the climate is drier, it becomes a truesemi-desert with ground not entirely covered by vegetation: "open" as opposed to "closed" vegetation. Examples include the north of theZF Mgcawu District Municipality, itself in the north of South Africa, and theKeetmanshoop Rural in the southeast of Namibia. In the north and east, dry forests cover an area of over 300,000 km2 in whichRhodesian teak and several species ofacacia are prominent. These regions are termedKalahari Acacia-Baikiaea woodlands AT0709.[16]
Outside the Kalahari "desert", but in the Kalahari basin, 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).[16]
Some of the areas within the Kalahari are seasonalwetlands, such as theMakgadikgadi Pans ofBotswana. This area, for example, supports numeroushalophilic species, and in the rainy season, tens of thousands offlamingos visit these pans.[18]
TheSan people have lived in the Kalahari for 20,000 years ashunter-gatherers.[19] They hunt wild game with bows and poisoned arrows and gather edible plants, such as berries, melons and nuts, as well asinsects. 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. Most of their hunting and gathering techniques replicate pre-historic tribes.Bantu-speakingTswana,Kgalagadi, andHerero and a small number ofEuropean settlers also live in the Kalahari desert. The city ofWindhoek is situated in theKalahari Basin.[citation needed]
^ P. D. Tyson FRSSAf & S. J. Crimp (1998) THE CLIMATE OF THE KALAHARI TRANSECT, Transactions of the Royal Society of South Africa, 53:2, 93–112, DOI: 10.1080/00359199809520380
^ P. D. Tyson FRSSAf & S. J. Crimp (1998) THE CLIMATE OF THE KALAHARI TRANSECT, Transactions of the Royal Society of South Africa, 53:2, 93–112, DOI: 10.1080/00359199809520380
![[icon]](/mt/?noimg=&dark=on&url=https%3a%2f%2fen.wikipedia.org%2fwiki%2fFile%3aWiki_letter_w_cropped.svg)
%2c_Kalahari.jpg)
.jpg)
.jpg)
