EGU21-7022, updated on 04 Mar 2021
https://doi.org/10.5194/egusphere-egu21-7022
EGU General Assembly 2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Unified model of sediment transport threshold and rate across subaqueous bedload, windblown sand, and windblown snow

Thomas Pähtz1, Yonghui Liu1, Yuezhang Xia1, Peng Hu1, Zhiguo He1, and Katharina Tholen2
Thomas Pähtz et al.
  • 1Zhejiang University, Institute of Port, Coastal and Offshore Engineering, Ocean College, Hangzhou, China
  • 2Institute for Theoretical Physics, Leipzig University, Leipzig, Germany

Nonsuspended sediment transport (NST) refers to the sediment transport regime in which the flow turbulence is unable to support the weight of transported grains. It occurs in fluvial environments (i.e., driven by a stream of liquid) and in aeolian environments (i.e., wind-blown) and plays a key role in shaping sedimentary landscapes of planetary bodies. NST is a highly fluctuating physical process because of turbulence, surface inhomogeneities, and variations of grain size and shape and packing geometry. Furthermore, the energy of transported grains varies strongly due to variations of their flow exposure duration since their entrainment from the bed. In spite of such variability, we here propose a deterministic model that represents the entire grain motion, including grains that roll and/or slide along the bed, by a periodic saltation motion with rebound laws that describe an average rebound of a grain after colliding with the bed. The model simultaneously captures laboratory and field measurements and discrete element method (DEM)-based numerical simulations of the threshold and rate of equilibrium NST within a factor of about 2, unifying weak and intense transport conditions in oil, water, and air (oil only for threshold). The model parameters have not been adjusted to these measurements but determined from independent data sets. Recent DEM-based numerical simulations (Comola, Gaume, et al., 2019, https://doi.org/10.1029/2019GL082195) suggest that equilibrium aeolian NST on Earth is insensitive to the strength of cohesive bonds between bed grains. Consistently, the model captures cohesive windblown sand and windblown snow conditions despite not explicitly accounting for cohesion.

How to cite: Pähtz, T., Liu, Y., Xia, Y., Hu, P., He, Z., and Tholen, K.: Unified model of sediment transport threshold and rate across subaqueous bedload, windblown sand, and windblown snow, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-7022, https://doi.org/10.5194/egusphere-egu21-7022, 2021.

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