A sediment transport equation for interrill overland flow on rough surfaces

TitleA sediment transport equation for interrill overland flow on rough surfaces
Publication TypeJournal Article
Year of Publication2001
AuthorsAbrahams AD, Li G, Krishnan C, Atkinson JF
JournalEarth Surface Processes and Landforms
Date Published2001
Accession NumberJRN00317
Call Number00784
Keywordsarticle, articles, hydrology, bedload, hydrology, hillslopes, hydrology, interrill flow, hydrology, overland flow, hydrology, sediment transport, hydrology, soil erosion, journal, journals, model, hydrology, model, interrill overland flow, model, sediment transport

A model for predicting the sediment transport capacity of turbulent interrill flow on rough sur4faces is developed from 1295 flume experiments with flow depths ranging from 3.4 to 43.4 mm, flow velocities from 0.09 to 0.65 m s-1, Reynolds numbers from 5000 to 26949, Froude numbers from 0.23 to 2.93, bed slopes from 2.7° to 10°, sediment diameters from 0.098 to 1.16 mm, volumetric sediment concentrations from 0.002 to 0.304, roughness concentrations from 0 to 0.57, roughness diameters from 1.0 to 91.3 mm, rainfall intensities from 0 to 159 mm h-1, flow densities from 1002 to 1501 kg m-3, and flow kinematic viscosities from 0.913 to 2.556 x 10-6 m2 s-1. Stones, cylinders and miniature ornamental trees are used as roughness elements. Given the diverse shapes, sizes and concentrations of these elements, the transport model is likely to apply to a wide range of ground surface morphologies. Using dimensional analysis, a total-load transpot equation is developed for open-channel flows, and this equation is shown to apply to interrill flows both with and without rainfall. The euation indicates that the dimensionless sediment transport rate Ø is a function of, and therefore can be predicted by, the dimensionless shear stress è, its critical value èc, the resistance coefficient u/u*, the inertial settling velocity of the sediment wi, the roughness concentration Cr, and the roughness diameter Dr. Testing reveals that the model gives good unbiased predictions of Ø in flows with sediment concentrations less than 0.20. FLows with higher concentrations appear to be hyperconcentrated and to have sediment transport rates higher than those predicted by the model. Copyright © 2001 John Wiley & Sons, Ltd.

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