The Kalahari Desert is considered a semi-arid savanna, with a clear wet and dry season. Despite the seasons, much variation in the hydrology of this location can be found when analyzing the different regions of the desert, specifically the outskirts, and the heart of the Kalahari. The groundwater recharge in the Kalahari Desert today is measured at about 5 mm a year towards the edges of this location, and as little as 1 mm a year in the central region of the desert.
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| http://www.photocircle.net/eu/photos/dennis-wehrmann/15361-Kalahari-Desert-Sunrise-Namibia |
The difference in groundwater recharge that is seen
throughout the different areas of the desert correlates to the amount of
rainfall measured at the edges of the Kalahari, compared to the center. Over
400 mm of annual rainfall has been recorded towards the outskirts of the
desert, with a much lower precipitation rate, less than 350mm, at the center.
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| Maps showing the location of the Kalahari Desert in Southern Africa, the heart of the desert towards the lower left side of Botswana https://www.pinterest.com/pin/558376053770450237/ https://www.pinterest.com/pin/380343131003168965/ |
Thus a pattern in the hydrology of the Kalahari Desert emerges,
with consistent high groundwater recharge near the edges, and significantly
lower recharge near the center.
Because of this pattern, we see landscapes closer to the
borders of the desert reflecting that of a high infiltration capacity
environment, with more vegetation, and a very dry, arid landscape of low
infiltration capacity towards the middle.
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| Examples of landscapes on the outskirts of the Kalahari, with more vegetation as a result of more rainfall http://2.bp.blogspot.com/-ZcZ52MoG2eE/VSZLMOXumkI/AAAAAAAADRs/Tr8Io4IM4Ns/s1600/roadsidewater1.jpg http://dave--kelly.blogspot.com/2010/05/amadwala-lodge-khama-rhino-sanctuary.html http://www.xflow.eu/en/2015/08/17/kalahari-desert-botswana/ |
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| Examples of drier more arid landscapes towards the center of the Kalahari http://geograph-sarah.blogspot.com/2010/02/kalahari-desert.html http://www.authorstream.com/Presentation/12dagati-149523-kalahari-desert-marr-entertainment-ppt-powerpoint/ https://www.pinterest.com/wayne1948/namibia-africa/ |
With less rainfall being absorbed by the earth in certain
parts of the desert, one can observe erosion in the form of rills and gullies,
as rainfall runs off quickly into streams.
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| Examples of rills and gullies, in dendritic drainage patterns, in the Kalahari as a result of rainfall in Low Infiltration Capacity areas http://media.gettyimages.com/photos/aerial-view-of-kalahari-desert-northern-cape-province-south-africa-picture-id475155325?s=170667a https://www.pinterest.com/pin/87960998942992427/ http://www.answers.com/Q/What_landforms_are_found_in_the_Kalahari_desert?#slide=1 |
Although some humans, like the San People, live near the
outskirts of the desert, due to the extreme conditions of the Kalahari, the
landscape is not very suitable for humans, as the annual rainfall in each
region struggles to support the vegetation and wildlife alone. An increase in
the groundwater table would provide more suitable conditions for human
accommodation, but such a thing would require an extreme and consistent annual
rainfall increase.
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| Some of the San People of the Kalahari Desert https://en.wikipedia.org/wiki/San_people http://www.dailymail.co.uk/femail/article-2590781/Meet-women-make-Bear-Grylls-look-like-wimp-The-people-Namibias-ancient-San-tribe-REAL-ultimate-survivors.html |
Interesting Video outlining where the Kalahari gets it's little moisture from. One way the groundwater table might increase in the future, providing more rainfall for the Kalahari, would be if the Maloti Mountains in Lesotho were to erode away.
https://www.youtube.com/watch?v=f_96xW6eF1Q
References:
http://www.hydrology.nl/images/docs/dutch/key/De_Vries_Groundwater_Recharge_Kalahari.pdf
https://www.britannica.com/place/Kalahari-Desert
https://ucdenver.instructure.com/courses/342696/files/3965142?module_item_id=898889
