Velocity
It is unlikely one will encounter a stream or river modeling equation without any knowledge
of it's velocity. Velocity plays a major role in the modeling of rivers or streams. Some ways
to obtain values for velocity are:
- USGS DATA
- State Agencies
- Universities
- Direct measurement
- Empirical formulas
The first three of the above are relatively easy to use as long as the river under study
has been monitored by others in the past. If these options are not viable, and a direct
measurment cannot be taken in time, an equation can be used to derive the velocity
according to other aspects of the river. Manning has developed a fairly good empirical
formula to estimate stream velocity.
where:
U = Average velocity in fps
n = Roughness Coefficient
Rh = Hydraulic Radius in ft = A/P
A = Cross-sectional area in ft2
P = Wetted Perimeter
So = Slope of the channel bed