The size and shape characteristics of the surface bed sediments in a sequence of four pools and four riffles were investigated in a small cobble-bed stream. The riffle sediments are both coarser and better sorted than the pool sediments. These differences are explained in terms of reversal of the bottom velocity/shear stress hierarchy between pools and riffles at high flow. Riffle sediments are also less spherical than pool sediments, but the differences in shape are entirely size-dependent. Thus it appears that sorting occurs by size, but not by shape, as sediments are deposited in pools and riffles.

First Page Preview

First page PDF preview
You do not currently have access to this article.