Estimation of Average Stream Velocity

Michael G. Waldon, M.ASCE

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**Abstract:** Stream tracer studies
provide information supporting diverse applications in environmental research
and management. Average stream velocity through a reach is often estimated from
tracer temporal profiles. This Technical Note addresses the calculation of
average reach velocity. It is shown here that, under steady flow, average reach
velocity over a fixed distance equals the spatial harmonic mean velocity.
Similarly, the average reach velocity from the point of tracer injection to a
fixed downstream measurement site is equal to downstream distance divided by
the harmonic mean tracer time-of-travel, rather than the commonly used temporal
centroid.

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**Waldon, M.G., 2004. Estimation of Average Stream
Velocity. ASCE Journal of Hydraulic
Engineering 130(11), 1119-1122.**