Quality Assessment: Physical
The S-shaped path of meandering streams prevents water from moving too quickly and flooding downstream ecosystems. The deep, cold pools of water provide ideal habitat for many species of fish even when overall stream-flow is reduced. The riffles help to hold water upstream during times of low stream-flow. Also, turbulence in the riffles mixes oxygen into the water. Natural stream-channel patterns, with their bends, pools, and riffles, are essential to decreasing flooding as well as providing a suitable habitat for certain aquatic plants and animals. For these reasons, it is important to assess the physical attributes of a stream when examining its water quality.
Measurements of a stream's physical attributes are used to describe the structure of a sampling site. This allows for the comparison of the biota and chemistry of similarly-structured streams at different locations. Measurements of a stream's physical attributes can also serve as indicators of some forms of pollution. For example, changes in temperature may indicate the presence of certain effluents, while changes in stream width, depth, and velocity, turbidity, and rock size may indicate dredging in the area.
and Catchment Area / Stream Order /
Forest Canopy / Width,
Depth, and Velocity / Rock Size / Turbidity
/ Total Solids / Temperature
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