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 degradation. Extensive held work was conducted during the dry seasons of 1991 and 1993. The positions in the terrain of the field observations were 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 SPOT image from different years. It was established that the nebkhas were formed by basically aeolian processes. Their occurrence was associated with areas having degraded vegetation and with human activities. Nebkhas were thus found to be good indicators of wind erosion and land degradation.