COMPARISON OF WIDTH AND FRICTION FACTOR PREDICTORS AND IMPLICATIONS

摘要

Bank-full stage data of sand-bed alluvial rivers, mostly of Indian origin were used to evolve the Lacey divergence relation between W, D, S, Q, and d_(50). Application of this relation to predict W in case of the same data for Indian rivers (Chitale 1977) as well as for U.S. rivers (Schumm 1969), and friction factor f in case of data of U.S. rivers (Schumm 1969), showed its marked superiority in respect of accuracy, which led to the following conclusions. The Lacey divergence formula in (24) is found to yield more accurate W and f predictions for alluvial rivers than several other available predictors, as shown in Figs. 1-3. The parameter τ_r is shown to be a measure of strength of bank material for stability, since τ_r = τ_(cr), where 觃(cr) is the critical shear ratio (τ_c actual/τ_c Lacey) for the bank material. The value of velocity V or discharge intensity q at the full bank stage estimated for a given set of D, S, and d_(50), using any of the friction factor predictors is also associated with a specific value of Q.