Measurements were taken in 3- and 1-ft rectangular flumes at USU to determine the surface velocity coefficients (SVC) for the float method used for open-channel flow measurement, and to obtain detailed cross-sectional velocity profiles under steady-state, uniform flow conditions. The calculated SVC were mostly for depths below one foot. Calculated SVC values were compared with previously published values, where applicable, and the cross-sectional velocity profiles were used to help calibrate a 3-D mathematical model for open-channel flow.; Results showed that the SVC did not change significantly with bed slope for a particular channel cross-section size. The calculated SVC values increased monotonically with increasing depth in one flume, while in the other flume the values increased to up to a certain depth, and then decreased with increasing depth. SVC varied as a function of channel base width, even with the same depth of water. Also, for depths less than 0.30-m, the previously published SVC values show the same behavior as the calculated SVC for depths equal to or greater than 0.30 m. Velocity profiles were plotted and compared with those generated by a 3-D mathematical model. The average and maximum velocities of the lab data and the model were significantly similar even though the profiles generated by the measured data and the model were distinctively different.
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