POOL/GLIDE AND RIFFLE/RUN QUALITY METRIC:

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.

RIFFLE/ RUN SUBSTRATE

This measure refers to the nature of the material comprising the substrate of riffles and runs and the degree to which it contributes to the stability of the bottom.

• The following Riffle/Run Substrates are considered in the QHEI Pool/Glide And Riffle/Run Quality metric:



• Stable
• Moderate to Stable
• Unstable

STABLE [2] The bottom is made up of cobbles and boulders, so that there is little or no contribution of the bottom to the stream's bed load. Riffle/Run Substrate QHEI Metrics NORP Main Menu

MODERATE TO STABLE [1] The bottom is made up of coarse gravel, larger than pea size. It may thus contribute some materials to the bed load, but only during flood conditions. At most times, the bottom is quite stable and does not move. Riffle/Run Substrate QHEI Metrics NORP Main Menu

UNSTABLE [0] The bottom is made up of pea-size gravel or sand, so that it can contribute materials routinely to the bed load, and so that there is considerable mobility to the riffle itself. Riffle/Run Substrate QHEI Metrics NORP Main Menu