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Buffington & Montgomery 1997
Buffington, J.M. and Montgomery, D.R. (1997). A systematic analysis of eight decades of incipient motion studies, with special reference to gravel-bedded rivers. Water Resources Research 33: doi: 10.1029/97WR03190. issn: 0043-1397.

Data compiled from eight decades of incipient motion studies were used to calculate dimensionless critical shear stress values of the median grain size, &tgr;c50*. Calculated &tgr;c50* values were stratified by initial motion definition, median grain size type (surface, subsurface, or laboratory mixture), relative roughness, and flow regime. A traditional Shields plot constructed from data that represent initial motion of the bed surface material reveals systematic methodological biases of incipient motion definition; &tgr;c50* values determined from reference bed load transport rates and from visual observation of grain motion define subparallel Shields curves, with the latter generally underlying the former; values derived from competence functions define a separate but poorly developed field, while theoretical values predict a wide range of generally higher stresses that likely represent instantaneous, rather than time-averaged, critical shear stresses. The available data indicate that for high critical boundary Reynolds numbers and low relative roughnesses typical of gravel-bedded rivers, reference-based and visually based studies have &tgr;c50* ranges of 0.052--0.086 and 0.030--0.073, respectively. The apparent lack of a universal &tgr;c50* for gravel-bedded rivers warrants great care in choosing defendable &tgr;c50* values for particular applications.¿ 1997 American Geophysical Union

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Abstract

Keywords
Hydrology, Erosion and sedimentation, Hydrology, Geomorphology
Journal
Water Resources Research
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Publisher
American Geophysical Union
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