NEBKHA DUNES AS INDICATORS OF WIND EROSION AND LAND DEGRADATION IN THE SAHEL ZONE OF BURKINA-FASO

Nebkha dunes, which develop by the trapping of sand within the body of a plant, were investigated in the Sahelian zone of Burkina Faso. The characteristics, location and age of nebkhas were analysed in order to assess their significance as indicators of wind erosion and land degr adation. Extensive held work was conducted during the dry seasons of 1 991 and 1993. The positions in the terrain of the field observations w ere determined by satellite-aided ground navigation technology (GPS). Multi-temporal studies of changes in vegetation cover at the different nebkha sites were carried out by comparing aerial photographs and a S POT image from different years. It was established that the nebkhas we re formed by basically aeolian processes. Their occurrence was associa ted with areas having degraded vegetation and with human activities. N ebkhas were thus found to be good indicators of wind erosion and land degradation.