Contribution of Granulometric Analyses to the Understanding of Wind Dynamics in the Figuig-Bouarfa Region (Eastern Morocco)

Morocco, like many arid countries, is facing desertification, particularly in its southern and southeastern regions. A clear indication of this process is the movement of sand dunes in the southern part of the country. Studying wind dynamics in this area provides insights into the conditions and processes driving desertification, including sand erosion, transport, and deposition. This study focuses on the dune sands in eastern Morocco, analyzing their granulometric properties to better understand transport mechanisms and wind dynamics in the region. Granulometric analysis was performed on various sand deposits to investigate aeolian transformations in the area. The results show that the sand deposits in the eastern region consist primarily of a well-sorted dominant granulometric fraction, along with a minor fraction. The sand grains range in size from very fine to medium (150 to 218.8 µm) and are classified as having good to fairly good sorting (36 to 114.2 µm). The grain size symmetry varies from weak to strong, with a range of –0.34 to 0, indicating a tendency toward either finer or coarser grains. The grain size distribution varies, ranging from platykurtic to very leptokurtic (0.7 to 2.15). The deposits display a unimodal distribution with a minor tail on both sides of the dominant mode, suggesting significant wind deflation. Five particle size classes were identified, reflecting the sands’ evolution under wind dynamics.