Wadi

Wadis are located on gently sloping, nearly flat parts of deserts; commonly they begin on the distal portions of alluvial fans and extend to inland sabkhas or dry lakes.

Water percolates down into the stream bed, causing an abrupt loss of energy and resulting in vast deposition.

Wadi sediments may contain a range of material, from gravel to mud, and the sedimentary structures vary widely.

Wind activity also generates sedimentary structures, including large-scale cross-stratification and wedge-shaped cross-sets.

The desert environment is characterized by sudden but infrequent heavy rainfall, often resulting in flash floods.

Nomadic and pastoral desert peoples will rely on seasonal vegetation found in wadis, even in regions as dry as the Sahara, as they travel in complex transhumance routes.

[4] Deposition in a wadi is rapid because of the sudden loss of stream velocity and seepage of water into the porous sediment.