Slide 4 of 20
Notes:
Although there are competing hypotheses, the most compelling explanation for the basic instability in coupled fluid flow and sediment transport that leads to braiding is that braiding results when multiple bars are formed within the channel. The number of bars (or bar mode) that develop as a result of topographic steering of flow and sediment transport is a function of the width/depth ratio of the stream channel. The greater this ratio the more bars. A recent review of the theory is given by Nelson (Nelson, J.M., 1990, The initial stabillty and finite-amplitude stability of alternate flow in straight stream channels, Earth Sci. Rev., 29, 97-115). Several important papers on the theory of both braided and meandering streams are published in River Meandering, (S. Ikeda and G. Parker, eds.) Water Resources Mon. 12, Am. Geophys. Union, 1989.
The above flume experiment in a laboratory sand-bed channel shows the evolution of the channel bed from a pattern of fairly regular, linguoid submerged bars to irregular bars with some emergent portions, forming a braided channel.
