The major part of North-West Africa consists of deserts where dominant dryness and high solar radiation prohibits any vegetation from growing. This makes human presence with economic activities related to traditional agriculture or grazing hardly sustainable.
High daily temperature differences and a lengthy erosion process significantly altered the region's geomorphology. Soil structures have been eroded for thousands of years. Over 90 % of the Sahara desert is made out today of large flat rocky surfaces or plateaus called Hammada’s. Made of small broken bare rocks, the Hammada’s are actually characterized by a very small surface roughness to wind..
The sand dunes common to our imagination represent actually only about 5 % of the entire surface of the Sahara desert.
The Atlantic Ocean’s junction with the Sahara desert creates a zone of global energy exchange dominated by steady winds spreading inland over a long distance. The Atlantic desert coastline stretching from Morocco to Senegal is about 2000 kilometers long. It represents one of the largest and windiest areas on earth.
Because of harsh climatic conditions, population densities in these areas are very low, concentrated around water supply sources. These constitute main attraction poles, for local communities living in a few cities over a vast territory.