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Abstract Understanding when gravel moves in river beds is essential for a range of different applications but is still surprisingly hard to predict. Here we consider how our ability to predict critical shear stress (τc) is being improved by recent advances in two areas: (1) identifying the onset of bedload transport; and (2) quantifying grain‐scale gravel bed structure. This paper addresses these areas through both an in‐depth review and a comparison of new datasets of gravel structure collected using three different methods. We focus on advances in these two areas because of the need to understand how the conditions for sediment entrainment vary spatially and temporally, and because spatial and temporal changes in grain‐scale structure are likely to be a major driver of changes inτc. We use data collected from a small gravel‐bed stream using direct field‐based measurements, terrestrial laser scanning (TLS) and computed tomography (CT) scanning, which is the first time that these methods have been directly compared. Using each method, we measure structure‐relevant metrics including grain size distribution, grain protrusion and fine matrix content. We find that all three methods produce consistent measures of grain size, but that there is less agreement between measurements of grain protrusion and fine matrix content.
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This content will become publicly available on March 1, 2026
Hydrologic pathways and baseflow contributions, and not the proximity of sediment sources, determine the shape of sediment hysteresis curves: Theory development and application in a karst basin in Kentucky USA
- Award ID(s):
- 1933779
- PAR ID:
- 10588816
- Publisher / Repository:
- Elsevier
- Date Published:
- Journal Name:
- Journal of Hydrology
- Volume:
- 649
- Issue:
- C
- ISSN:
- 0022-1694
- Page Range / eLocation ID:
- 132300
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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