Friday, February 15, 2008

Okovango "Delta"

I was recently given a copy of the Planet Earth series (with David Attenborough), which I guess is a fairly recent set of pretty slick nature-type programs with some absolutely incredibly images. Anyway, on one of the episodes (I think the first one, “Pole to Pole”), which sort of dealt with water and how its distribution controls and effects ecosystems, there was a pretty cool segment about the Okovango “delta”, which is a huge terminal splay of the Okovango river that is completely land-locked, and empties into the Kalahari desert.

Sedimentologically, the Okovango system has become a sort of controversial model for a “terminal fan” or “subaerial fan” fluvial facies (see Stanistreet and McCarthy, 1993, Sedimentary Geology, and North and Warwick, 2007 JSR for a pretty sound rebuttal of the whole idea). I suspect that the presence of the distributary network has more to do with the presence of a relict lake basin in the terminal position, as opposed to any intrinsic river process unique to the Okovango. Regardless, it is still an absolutely incredible place, so I thought I’d post some nifty pictures, garnered from NASA World Wind (a Google Earth simulacrum). Click on 'em to make 'em big.
This first image just shows the Okovango Delta in the upper portion of the image, sort of near the center of Africa; its a pretty big feature!

This is a close up composite image of the distributary system of the Okovango.
The drainage basin of the Okovango.


Jeannette said...

I've seen that episode - - it's awesome!

BrianR said...

Nice post ... I love that episode too. I remember the part with the aerial shots showing the animals cutting "channels" through the wetlands. Somebody should do a study on the effects of animal trails on sediment dispersal...if they haven't already.

Andrew Alden, Oakland Geology blog said...

The seismologist Christopher Scholz wrote a wonderful book, "Fieldwork," about his expedition into the Kalahari and the Okavango Delta in 1974. Long out of print and cheap on the Internet, and a great tale with elephant stampedes, odd equipment malfunctions in the sacred Bushman areas, and swamp wrasslin'.

Philippa said...

Thank you for your article, really helpful material.