Terminal pans are the endpoints of rivers that no longer make it all the way to the sea - or do they?
Image below of Sossusvlei and the (much larger) Tsondap vlei in the midst of the Namib Dune sea
Namibia has several striking examples of terminal pans - Sossusvlei being the most well known. Deadvlei is undoubtedly the most photographed with its ghostly trees dotting the pan. The word ‘vlei’ is Afrikaans for pan which is a shallow, natural body of water - although in Namibia, water is seldom found at ground level, however the massive Camelthorn trees found at Sossusvlei speak of underground sources of water. Because of the large surface area, even when there is water present, evaporation is fast, leaving a rich mineral deposit often starkly white.
Image right, closer view of the terminal pans at Sossusvlei
Sossusvlei was formed when the great sleeping giants of the Namib dune sea cut the ephemeral Tsauchab river off from the sea. Fed by infrequent but often high rain discharge on the inland escarpment, the vlei is now some 60 km from the coast. Ancient offshore canyons on the Namibian continental shelf however indicate that this river did once reach the sea south of Meob Bay and fresh water springs can still be found on the edge of the dunes at Fishersbrunn.
When pans are cut off from the river’s course - as in the case of the picturesque Deadvlei, closed off by a change in the course of the Tsauchab river some 600 years ago, the river no longer reaches the vlei at all, leaving the eerie skeletal remains of dead trees on a stark white surface. The grey-whiteness is the result of calcareous silts derived from weathering of limestones and dolomites from the escarpment.
Image left - several pans around Sossusvlei, now all cut off from the original course of the Tsauchab river.
The 4 800 square km Etosha pan - the name is thought to mean ‘great white place’ - is the end point of the huge Cuvelei drainage system which originates in the highlands of Angola. Unlike the Okavango Delta which has fixed water courses, the Oshona/Cuvelei is a flood-plain system which shifts its course every year, terminating in the Etosha pan.
Image below of Etosha showing the extent of the Cuvelei drainage system above it.
In the rainy season, the ‘new beginnings’ of these pans is that they are host to migratory birds feeding and breeding during Namibia’s long hot summers. In good rainy years, massive flotillas of fuchsia Flamingoes brighten up the stark white pans - a sight to behold!
Naye Naye pan, featured in our 2022 Bushmanland Exploratory Safari, had water so long it even attracted hippo from the distant (perennial) Okavango river.
Image right of a small flotilla of Greater Flamingoes on Naye Naye pan still with water.
With evaporation of open water in these arid areas at 3000 - 4000 mm/year, many pans - including Etosha seldom kept their water long and were traditionally a rich source for salt harvesting. Now commercial salt industries along the Namibian coast have taken over and the pans are left to the birds and wildlife….as it should be.