University of Roorkee, Roorkee (U.P.).
The varied flow equation given by Chow has been used to obtain dimensionless plots for the lengths of surface profiles in a few typical cases. A wide rectangular channel has been considered and relationships obtained for the lengths of M1, M2, C1, C3 and S2 profiles. The objects of this investigation were firstly to provide plots from which the length of the varied flow profile can be read directly and also to interpret these plots to study the effect of variation of Manning’s ‘n’ on tho lengths of these profiles. It is seen that the lengths of M2, G1, C3 and S2 profiles are strongly influenced by variation in ‘n’ other parameters remaining constant. But the length of the M1 profile is seen to be practically independent of the channel roughness. Thus one could perform computations with any, but realistic value of ‘n’ and get satisfactory results for the lengths of the M1 curve The extremely simple form of Equation (9) gives the length of M1 curve in the oommonly encountered range of Froudo number from 0.10 to 0.40.
