Comparison of hydraulic geometry between sand- and gravel-bed rivers in relation to channel pattern discrimination

A comparison has been made between the hydraulic geometry of sand- and gravel-bed rivers, based on data from alluvial rivers around the world. The results indicate a significant difference in hydraulic geometry among sand- and gravel-bed rivers with different channel patterns. On this basis, some diagrams for discrimination of meandering and braided channel patterns have been established. The relationships between channel width and water discharge, between channel depth and water discharge, between width-depth ratio and water discharge and between channel slope and water discharge can all be used for channel pattern discrimination. The relationship between channel width and channel depth can also be used for channel pattern discrimination. However, the accuracy of these relationships for channel pattern discrimination varies, and the depth-discharge relationship is a better discriminator of pattern type than the classic slope-discharge function. The cause for this difference has been explained qualitatively. To predict the development of channel patterns under different natural conditions, the pattern discriminator should be searched on the basis of independent or at least semi-independent variables. The relationship between stream power and bed material grain size can be used to discriminate channel patterns, which shows a better result than the discriminator using the slope-discharge relationship. Copyright (C) 2004 John Wiley Sons, Ltd