Comparison of Friction Velocity with other Roughness Parameters

Abstract

Channel slope is dominant parameter as
compared to hydraulic radius for friction
velocity. Friction velocity increases in steep
slope of channel as compared to hydraulic
radius. Whereas we get more value of
Manning’s roughness coefficient with respect to
hydraulic radius as compared to channel slope.
Also Chezy’s resistance factor is more with
respect to channel slope as compared to
hydraulic radius. We get more value of mean
depth of flow against friction velocity as
compared to Manning’s roughness coefficient.
Since friction velocity is more effective in high
velocity of flow and roughness is more effective
in high velocity of flow to reduce velocity of flow
and hence increase in depth of flow. We get
more value of mean depth of flow against
Chezy’s resistance factor as compared to
friction velocity and Manning’s roughness
coefficient. We get more velocity of flow against
Chezy’s resistance factor as compared to
friction velocity hence there is more mean depth
of flow for Chezy’s resistance factor as
compared to friction velocity & Manning’s
roughness coefficient. Hence friction velocity is
beneficial for lesser velocity of flow whereas
Chezy’s resistance factor is useful for more
depth of flow from roughness point of view. Also
Mannung’s roughness coefficient is useful for
preventing erosion because we get lesser value of
maximum permissible velocity with respect to
Manning’s roughness coefficient as compared to
friction velocity and Chezy’s resistance factor.