Boundary Layers, Flow Microenvironments and Stream Benthos

Abstract

Water movement is the dominant physical feature of rivers and streams, yet, despite the very large amount of effort that has been devoted to research in lotic ecosystems, few studies have attempted to describe lotic flow regimes in more than the most general terms. Sing mean velocity inadequate. Need velocity profiles, and heights of roughness elements (substrate micoprofiles) - shear velocities, roughness reynolds numbers, boundary layer thikness. Important features is the horseshoe vortex system. These influence the distribution of macroinvertebrates and the ecology of suspension-feeding organisms.