Terminal Pans, the endpoints of rivers that no longer make it all the way to the sea - Namibia has several striking examples: Sossusvlei is possibly the most well know, while Deadvlei is undoubtedly the most photographed, and then the largest, Etosha at 4 800 square km. A vlei or pan is a shallow, natural pool of water - with or without the water. Pan’s are often associated with the accumulation of salt and other minerals.
Image right: Etosha with the massive Cuvelei drainage system coming out of Angola
In the rainy season countless temporary pans host migratory birds feeding and breeding in our long, hot summers. In good years, massive flotillas of fuchsia Flamingos brighten up the stark white pans - Etosha in Namibia and Makadikadi and Sua in Botswana come alive with birds.
Etosha, meaning ‘great white place’, is the endpoint of the huge Cuvelei drainage system (image) originating in the Angolan highlands. Unlike the Okavango Delta which has a fixed water course, the Oshona/Cuvelei is a flood-plain system which shifts every year. The water either evaporates or eventually infiltrates the sand layer below.
Sossusvlei (image right) formed when several arms of the sleeping giants of the Namib dune sea - the star huge dunes, cut the ephemeral Tsauchab River off from the sea. Now some 60 km from the coast, ancient offshore canyons on the Namibian continental shelf indicate that these rivers did once reach the sea.
When pans are cut off from the river’s course - as is the case of the picturesque Deadvlei (image right) - closed off some 600 years ago - the river no longer reaches the vlei at all, leaving the eerie skeletal remains of trees and a stark white surface.
With evaporation off open water in these arid area at 3000 - 4000 mm/year, many pans - including Etosha - were traditionally harvested for their salt. But now commercial salt industries in Walvis, Swakopmund and Cape Cross have taken over and the pans are left to the birds and wildlife.
As it should be.