Ephemeral Rivers - lifelines of desert adaptation

Updated: Jan 25, 2020

ephemeral |ɪˈfɛm(ə)r(ə)l, -ˈfiːm-|

adjective - lasting for a very short time

Among Namibia’s greatest assets are its dramatic landforms that both delight and enchant giving a new dimension of wonder for the processes that formed this ancient land.

Ephemeral rivers as landforms are a feature of all our riding safaris, although the Fish is arguably a perennial river since it almost always has some water, even if a mere trickle at times.

Right: Kuiseb pools

While many of Namibia’s westward flowing rivers might appear to be inactive – and some even almost invisible, they have played a role in forming the desert landscapes we ride across.

The Kuiseb – which we cross on our Namib Desert Safari (image below) – has been known to reach a flood level of 3 metres and to flow for as long as 103 days, giving it enough power to form a dramatic end to the over 400 km dune sea that has its origins south of Luderitz. The high canyon walls of the Kuiseb mean there is almost always some water throughout the year sustaining surprisingly large herds of Zebra, Oryx, Ostrich and birds.

Ephemeral river systems are also linear oasis, lifelines of riparian woodland made up of enormous Camelthorn, Anna trees the pods from which are rich in protein and are available for most of the year. Large shrubs such as the Salvadora and extensive reed beds give shelter and food to smaller animals. Occasional springs occur in many of the seemingly dry rivers, sometimes supplying enough water for large herds of Elephant to venture far into the western deserts.

These westward flowing ephemeral rivers have their origin in the interior highlands some having catchment areas of over 21 000 square km. They flow westward across the Namib Desert occasionally reaching the sea like the Swakop and Huanib Rivers.

Left, desert adapted lions reluctantly crossing the flooding Huab river

Image right of the Swakop River reaching the sea in 2010

Others, like the Tsauchab (left) whose passage is blocked by massive dunes, form terminal pans of which Sossusvlei is a dramatic example.

Image left of the Tsauchab flowing strongly into Sesriem Canyon

By the time the rains come in summer, the sun-baked soil has low permeability so the rushing head-waters often surprising unwary campers even carrying their cars down-stream. It may not even have rained nearby but nevertheless these dry riverbeds can change into raging torrents in under an hour – an awesome sight to behold. To see these seemingly benign rivers in flood is an unforgettable experience.

Image below of a flooded road - best not to cross these seemingly benign rivers - they have carried many a vehicle downstream!

In thinking about rivers we are perhaps reminded that a ‘river’ flows through all of us too, a river seeking the ocean. A profound passage from a most unlikely source - Winnie the Pooh. Hopefully we too will give up running and jumping and come to know there is no hurry…

By the time it came to the edge of the Forest the stream had grown up, so that it was almost a river, and, being grown-up, it did not run and jump and sparkle along as it used to do when it was younger, but moved more slowly. For it knew now where it was going, and it said to itself, “There is no hurry. We shall get there some day”. But all the little streams higher up in the Forest went this way and that, quickly, eagerly, having so much to find out before it was too late”. A.A. Milne

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