Quantifying the role of bed surface topography in controlling sediment stability in water‐worked gravel deposits

Abstract

This study uses measured bed topography scans and fractional bed load transport rate data obtained from previous laboratory studies of gravel transport to examine the influence of the local grain‐scale topography on grain entrainment and fractional transport rates. A simple steady state fluid model is developed to impose fluid forces onto the exposed areas of the bed surface. Image analysis is used to identify the surface grains and simple physically based algorithms are used to include the effects of sheltering. Comparisons of modeled and experimental fractional transport rates show that remote sheltering has a very strong influence on grain entrainment. With the effects of remote sheltering included, the model was found to be able to predict fractional transport rates well for a range of bed topographies and feed conditions. Further studies using a wider range of bed shear stresses would allow the effects of turbulence and bed re‐arrangement to be included in the model.