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Probability Distributions of Particle Hop Distance and Travel Time Over Equilibrium Mobile Bedforms

The joint probability distribution of streamwise particle hop distance, lateral particle hop distance, and travel time constrains the relationships between topographic change and sediment transport at the granular scale. Previous studies have investigated the ensemble characteristics of particle mot...

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Bibliographic Details
Published in:Journal of geophysical research. Earth surface 2020-07, Vol.125 (7), p.n/a
Main Authors: Ashley, Thomas C., Mahon, Robert C., Naqshband, Suleyman, Leary, Kate C. P., McElroy, Brandon
Format: Article
Language:English
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Summary:The joint probability distribution of streamwise particle hop distance, lateral particle hop distance, and travel time constrains the relationships between topographic change and sediment transport at the granular scale. Previous studies have investigated the ensemble characteristics of particle motions over plane bed topography; however, it is unclear whether reported distributions remain valid when bedforms are present. Here, we present measurements of particle motion over bedform topography obtained in a laboratory flume and compare these to particle motions over plane bed topography with otherwise similar conditions. We find substantial differences in particle motion in the presence of bedforms that are relevant to macroscopic models of sediment transport. Most notably, bedforms increase the standard deviation of streamwise and lateral hop distances relative to the mean streamwise hop distance. This implies that bedforms increase the streamwise and lateral diffusion lengths and, equivalently, increase diffusive‐like fluxes. Key Points Particle travel times over bedforms are exponentially distributed as proposed for planar beds Streamwise and lateral hop distances over bedforms are not Weibull distributed as proposed for planar beds Bedforms increase the variance in streamwise and lateral hop distances and increase diffusive‐like transport
ISSN:2169-9003
2169-9011
DOI:10.1029/2020JF005647