Stream Flow
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Stream flow is the volume of water that moves past a fixed point during a specific interval of time. The usual unit in which flow is measured is cubic feet per second (cfs) - the number of cubic feet of water moving down the stream channel in one second. Think of it as the width of the stream at some point, times its average depth times its average velocity: width in feet times depth in feet times velocity in feet per second equals flow in cubic feet per second (width ´ depth ´ velocity). Knowing the flow is critical in calculating the amount of a contaminant in a stream. When we test for bacteria or nutrients or total dissolved solids, we only determine the concentration in the water. Not until we measure flow can we quantify the actual amount being carried through the system (the amount is equal to the flow multiplied by concentration).

Among the various ways in which stream flow affects water quality:

 

· Flow influences the ability of a stream to dilute pollution; large, swift rivers have a greater ability to dilute pollution than smaller streams.

· Flow and velocity affect the available oxygen level in water: higher velocities and flows generate higher levels of turbulence which in turn, cause more air to be mixed within the flow. Streams with higher flows generally have more oxygen available for aquatic organisms.

· Flow controls the amount of sediment that is transported in a stream. Streams with higher velocities and larger flows can transport greater amounts of sediment

Observations made on Stream Team about stream flow: