Empirical Studies in Alluvial Streams

Abstract

Meander flow takes place in one single channel which oscillates more or less regularly with amplitudes that tend to increase with time. Meanders are found in beds of fine sediments with gentle slopes. In this study, effort will be made to investigate meanders’ turbulent boundary layer and to improve the present knowledge about the river meandering phenomena. It is assumed that the development of the perturbations which develop into meanders or braids, is longer than the width of the channel. Interaction be tween the flow and mobile boundaries produces channel patterns which are classified as meandering or braided. It is therefore long compared with the ripples or dunes which cover the bed of such a channel and whose wave length is shorter than the width of the channel. The variation of resistance to flow and rate of transport of bed material with velocity are discussed briefly and taken into account. Meander flow and meander shear stress distribu tion of the channel are described. The basis is a steady, two-dimensional model of flow in an alluvial channel with variable curvature. The meander development is described by forcing a travelling, small-amplitude channel alignment wave on the system, and determining the growth characteristics of the wave. Laboratory data are used to verify the formulas.