Document Type : Research Article
Author
Assistant Professor in Geomorphology (Wind Erosion), University of Tehran, Tehra, Iran
Abstract
The study of dunes morphology provides a valuable tool for investigating wind systems and the identification of sand sources (removal region). The wind direction is the primary factor controlling the dune shape and elongation. In deserts jubject to wind from different directions and with comparable magnitude, dunes are formed having different morphologies. The sand dunes are either perpendicular or parallel to the wind direction. The purpose of this study was to analyze the morphology of sand dunes under bimodal winds using conventional models. Observations showed that the linear (seif) dunes formation are due to the elongation of a barchan horn. These dunes are created by a bimodal wind regime with a strong peak from the result of northwest and west winds and a weaker peak from the east winds with a divergence angle of 135°. Sinuous crest lines of seif dune grow directly by west and east winds. The study showed that the evolution trend of the sand dunes of the region, under the strong northwest wind, first shield dune transforms into a dihedral barchans. At this stage, wind erosion on the back of the sand pile (shield dune) leads to the formation of a crest perpendicular to the wind direction and then to the formation of a slip face downwind. According to the effect of the magnitude and change of direction in the Westerly and Easterly winds, the western wing of barchan begins to extend and turns into a dentate seif dune.
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©2024 The author(s). This is an open access article distributed under Creative Commons Attribution 4.0 International License (CC BY 4.0)
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