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Resistance to overland flow due to bed‐load transport on plane mobile beds
Author(s) -
Hu Shixiong,
Abrahams Athol D.
Publication year - 2004
Publication title -
earth surface processes and landforms
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.294
H-Index - 127
eISSN - 1096-9837
pISSN - 0197-9337
DOI - 10.1002/esp.1123
Subject(s) - froude number , bed load , sediment , sediment transport , dimensionless quantity , geology , surface runoff , hydrology (agriculture) , resistance (ecology) , geotechnical engineering , flow (mathematics) , geomorphology , geometry , soil science , mathematics , mechanics , physics , ecology , biology
Abstract During bed‐load transport by overland ow, momentum is transferred from the ow to the bed via grain collisions, resulting in a decrease in ow velocity and an increase in ow resistance, herein termed bed‐load transport resistance. In overland ow on mobile plane beds, total ow resistance f consists of grain resistance f g and bed‐load transport resistance f bt . In order to identify and evaluate the relative importance of the factors controlling f bt , 38 ume experiments were performed on slopes of 2·7 and 5·5° using sediment with median diameters of 0·74 and 1·16 mm. All ows were supercritical and turbulent. This study is an extension of a recent study by Gao and Abrahams ( Earth Surface Processes and Landforms 2004, vol. 29, pp. 423–435). These authors found that f bt is controlled by three factors: sediment concentration C , dimensionless sediment diameter D * , and relative submergence h/D , where h is ow depth, D is median sediment diameter. However, a new dimensional analysis identies two additional factors: Froude number F and slope S . Multiple regression analyses reveal (1) that these ve factors together explain 97 per cent of the variance of f bt , and (2) that S controls f bt entirely through C . The variable C is therefore redundant, and a new functional equation relating f bt to D * , h/D , S and F is developed. This equation may be used to predict f bt . An advantage of this equation is that it may be used to predict f bt without measuring bed‐load transport rate. Copyright © 2004 John Wiley & Sons, Ltd.