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 meaure refers to how fast the current is moving within pools and riffles.
Small to moderate areas of circular current motion, usually formed in pools immediately downstream from riffle/run areas or in areas characterized by large boulders below the surface of the stream.
Mostly non-turbulent flow with small standing waves in riffle/run areas. The water surface may be partially broken, but there is a visibly connected surface.
Non-turbulent flow that is detectable and visible (i.e. floating objects are readily transported downstream). The water surface is visibly connected.
Water flow is perceptible, but very sluggish.
Extremely turbulent and fast flow with large standing waves. The water surface is very broken, and it does not have a clearly definable, connected surface. This flow is usually found only in gorges and dam spillway tailwaters.
Water flow that is perceptible only in the interstitial spaces between substrate particles in riffle/run areas. The water flows through the substrate rather than over it.
No flow is evident anywhere, leaving standing pools that are separated by dry areas. There may be discernable flow during wet seasons, but there is essentially no flow for at least some of the time.