Relations between wind data and geomorphology in aeolian sand geodynamics

Aeolian sand migrations were studied in two areas of the north-western Sahara Desert: the 'Sand River' of Cape Juby, on the Atlantic shore of the Sahara and the Southern piedmont of the Sahara Atlas. The research was conducted on several years of wind data, as well as by the field study, photo-interpretation and remote sensing of dune fields. Aerological data were processed with B. Choppy's software, SABLES, which converts wind data into potential displacement coefficients of the aeolian sands. These coefficients are themselves transposed into volume and mass of displaced sand. The similarity between the field data and the results obtained by calculations is remarkable for both areas under study. A new scale for the study of dune forms is proposed: when the sources of sand have a precise topographical limit, the downwind edges of the dune fields indicate the sand migration directions, even in areas where these directions are not pronounced. They can thus be used in the study of the current and past displacements of sand and in the palaeoclimatic reconstructions.