Multi-temporal Quantification of Sand Flux Using BSNE and Leatherman Traps in the Middle Drâa Watershed, Morocco

Abstract

Aeolian processes represent a dominant geomorphological force in arid and semi-arid regions, where wind-driven sediments’ transport strongly influences landscape evolution and sediment redistribution, particularly in oasis systems such as those in the Middle Drâa Valley. This study aims to quantify bimonthly and instantaneous aeolian dynamics in the downstream area of Ternata, southeastern Morocco, to better understand the relationships between wind conditions, sediment flux, and measurement height. Bimonthly measurements were conducted using the Big Spring Number Eight (BSNE) sampler, while instantaneous measurements employed Leatherman’s device, with sand traps strategically placed in minimally disturbed areas and on dune crests. Results demonstrate a clear cause–effect relationship: wind speeds exceeding a critical threshold significantly increase sediment transport, with the highest mobilization observed at lower altitudes. Saltation was identified as the predominant transport mode, while suspension contributed to a lesser extent. Total sediment fluxes measured over bimonthly periods reached substantial values, highlighting the intensity of aeolian activity in this region, whereas instantaneous measurements captured short-term variability associated with gusts and directional shifts. These observations confirm that local topography and wind dynamics jointly control sediment flux patterns. The study provides new insights into the mechanisms driving sand movement in arid landscapes and emphasizes the importance of considering both temporal scales of measurement. These findings offer a scientific basis for developing dune management and stabilization strategies and underscore the need for proactive measures to mitigate sand encroachment and protect vulnerable oasis ecosystems.