Meandering Effect for Evaluation of Roughness Coefficients in Open Channel Flow

Abstract

During uniform flow in an open channel the resistance is dependent on a number of flow and geometrical parameters. The usual practice in one dimensional flow analysis is to select an appropriate value of roughness coefficient for evaluating the carrying capacity of natural channel. This value of roughness is taken as uniform for the entire surface and for all depths of flow. The resistance coefficients for meandering channels are found to vary with flow depths, aspect ratio, slope and sinuosity and are all linked to the stage-discharge relationships. Although much research has been done on Manning's n for straight channels,a last word has not been spoken on the roughness values for meandering channels. An investigation concerning the variation of roughness coefficients for meandering channels with slope, sinuosity and geometry are presented. The loss of energy in terms of Darcy-Weisbach coefficient f are evaluated. A simple equation for roughness coefficient based on dimensional analysis is modeled and tested with the recent experimental data. The method gives discharge results that are quite comparable to that of the observed values as well as with other published data.