watershedplus:

The Adjder oasis in Algeria uses depressions excavated from the sand to reach shallow aquifers where the water is pumped to irrigate the palms, under which vegetables are grown.
The sharp edges along the rim of the oases are sand fences built to keep the mobile dunes from burying the gardens.

From The New Scientist via Seeing Landscapes
Picture by George Steinmetz

pretelos:

Boots on Flickr.

Boots on Flickr.