This metric describes the characteristics of areas with the slowest and fastest currents.
Pools and glides are areas of slow current. Both are typically bowl-shaped features in the stream bed, and they are often the areas of greatest stream width. Pools do not show much, if any current at the surface; glides show slow steady movement.
Riffles and runs are areas of rapid and turbulent movement. Riffles are typically fairly shallow and show the most turbulent movement in the stream, where the water moves over rocks or uneven bedrock bottom. Runs may be deeper and show turbulent flow over an uneven bottom.
This measure describes the degree that the cobble, gravel, and boulder substrates are surrounded by fine material (sand and silt), so that they cannot easily be dislodged.