'The Hoanib Valley in Namibia is a dry river valley with a wide sandy bed which runs only once or twice a year. This is when there is rain in the hinterland and the river flows as a flash flood lasting a few days at a time. The sandy bed of the river is filled with huge acacia trees against which the floods have piled up tangled masses of debris from upstream. The fact the trees survive illustrates how rare the flash floods are, and how sturdy the acacias are as well, rooted as they are in river sand. This part of the Hoanib is cutting right through the Namib desert so it recieves no rain - the trees survive of the water that flows under the sand year round. So this is a desert region of Namibia that has lots of shade!'

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