Incomplete self-similarity and flow velocity in gravel bed channels

Velocity measurements, previously carried out using both a miniature curren t flowmeter and an acoustic Doppler velocimeter, are used to verify the app licability of the incomplete self-similarity theory to deduce the velocity profile in a gravel bed channel. Then, for the velocity profiles having the maximum value below the free surface and for the S-shaped profiles, the po wer velocity distribution is corrected using a new divergence function. For each value of the depth sediment ratio the nondimensional friction factor parameter is calculated by integration of the measured velocity distributio ns in the different verticals of the cross section. Finally, a semilogarith mic flow resistance equation is empirically deduced.