Subaqueous barchans and plane beds from deposition of quartz silt
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The suspension flow of quartz silt (geometric mean grain size of 4.15 µm), in unfavorable conditions for deposition, is the motivation for the development of different bed morphologies. Particles deposit over a plane nonerodible surface and develop well-defined barchan ripples, barchanoids, and plane beds in flume experiments. Bedload transport of quartz silt by bedform migration is several orders of magnitude smaller than the suspended transport. The final bed morphology is controlled by the suspended sediment concentration and running time of the experiment. The average dimensions of the bedforms after 1-day experiments are 4.93 cm wide, 10.33 cm long, and 0.45 cm high. Cohesive plane beds appear after 2-day and 3-day experiments with very high sediment concentrations (= 22.5 kg=m3). Viscous effects are deemed relevant for the formation of the beds.
CitationCapape, S., Martín-Vide, J.P., Colombo, F. Subaqueous barchans and plane beds from deposition of quartz silt. "Journal of Hydraulic Engineering", 1 Desembre 2016, vol. 142, núm. 12, p. 06016020-1-06016020-7.