| Summary: | One of the most important steps in the mechanism of sediment transport is the initial motion of bed load transport. The initial motion of bed load transport at clear-water flow have been studied extensively and known quitely well in the litarature, while for non-clear water flow i.e., suspended sediment flow, the knowledge about initial motion is still insufficent and incomplete. One of the subjects related with the initial motion of sediment transport are velocity and sediment suspension distributions which will be studied intensively here.
To achieve this objective, laboratory experiments on velocity and sediment suspension distributions were conducted, using the sediment-recirculating flume. Electromagnetic currentmeter and foslim-probe were used, respectively, to measure 40 velocities and 40 sediment concentrations distributions. Flow variations were conducted by combining two types of bed materials with five slope variations for each bed material, and five-discharge variations for each slope variations, in which one discharge is without sediment transport and the others four are with sediment transport.
The results of the laboratory experiment show that, inflow with sediment suspension, the constant value of the log law velocity distribution, Br, is 8.5 ± 15%, and the von Kcirmcin's universal constant, x, is 0.4 ± 10%. These values are still in the range of x and Br-values in clear water flow, which means that the sediment suspension used in this study do not influence the x and Br-value. For flows with initial bed material sediment motion, either the velocity and sediment suspension distributions, show specific difference trends compared with the ones without sediment transport and the ones with sediment transport. Rouse equation as well as Tanaka-Sugimoto equation can predict sediment suspension distributions satisfactory.
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