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|Title:||Modified Laursen method for estimating bed-material sediment load|
|Authors:||Flood Control Channels Research Program (U.S.)|
Madden, Edward B.
|Publisher:||Hydraulics Laboratory (U.S.)|
Engineer Research and Development Center (U.S.)
|Series/Report no.:||Contract report (U.S. Army Engineer Waterways Experiment Station) ; HL-93-3.|
Abstract: The sediment transport function developed by Emmett M. Laursen was adopted for the Arkansas River navigation project because it expresses transport rate using tern that permit separating the effects of hydraulic and sediment parameters. However, in attempting to reproduce measured data from the lower Arkansas River, the Laursen function gave results that were systematically low. The same trend appeared when the function was applied to Missouri River data. Therefore, Laursen's functional relationship was replotted for the Arkansas River planning studies based on Arkansas River data. Subsequently, another graph of the relationship was developed using data from several other rivers. The work reported in this study is an effort to collapse those functional relationships into a single graph. The approach was to introduce a correction coefficient based on Froude number. The resulting relationship was tested using data from eight field sites and five flume studies. Results, with adjustments for Froude number effects, are satisfactory for sediment sizes ranging from 0.031 mm to 4 mm, flow depths from 0.25 to 54 ft, flow velocities from 0.85 to 7.7 fps, energy gradients from 0.00001 to 0.1 ft/ft, water temperatures from 36 to 90 °F, and Froude numbers from 0.07 to 1.7 except when the grain tractive force is less than about two times the critical tractive force. Sediment transport is very small in this case, and there is probably a hiding effect beyond that included in Laursen's formulation.
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