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measurement depts. The method used to calculate the mean velocity in a vertical
depends on the number of point velocity measurements made within a vertical.
Methods implemented for determining mean station velocity in a vertical are based on
the following literature,
• ISO 748 – 2007, Hydrometry - Measurement of liquid flow in open channels using
current meters or floats,
• WMO-No. 1044, Volume I – Fieldwork, 2010.
The methods implemented in FlowTracker2 for determining the Mean Station Velocity
are defined in
Table
Method
Measurement Depth
0.6
0.6 * depth
0.2/0.8
0.2 * depth
0.8/0.2
0.8 * depth
0.2 * depth
.2/.6/.8
0.6 * depth
.8/.6/.2
0.8 * depth
Ice 0.6
0.6 * effective depth
Ice 0.5
0.5 * effective depth
Ice 2/8
0.2 * effective depth
0.8 * effective depth
Ice 8/2
Kreps 2-
0.0 (near surface)
Kreps 2+
0.62 * depth
0.0 (near surface)
0.2 * depth
5 Point+
0.6 * depth
5 Point-
0.8 * depth
1.0 (near bottom)
0.0 (near surface)
0.2 * depth
6 Point+
0.4 * depth
6 Point-
0.6 * depth
0.8 * depth
1.0 (near bottom)
Vertical
Any number of points at
Velocity
user-specified depths
Curve
FlowTracker2 User's Manual (January 2019)
5:2.
Table 5-2 - Determining Mean Station Velocity
V
mean
V
mean
V
mean
V
mean
(Correction Factor 0.92 can be changed by user)
V
mean
(Correction Factor 0.88 can be changed by user)
V
mean
V
mean
V
mean
V
mean
V
mean
Measurements can be made in any order; they are sorted
by depth to calculate the integrated mean velocity. Repeat
measurements at the same depth are averaged prior to
calculating the integrated velocity.
Mean Velocity Equation
= CF * V
0.6
= CF * ((V
+ V
) / 2)
0.2
0.8
= CF * ( (V
+ 2*V
+ V
0.2
0.6
= 0.92*V
0.6
= 0.88*V
0.5
= CF * ((V
+ V
) / 2)
0.2
0.8
= CF * ( 0.31*V
+ 0.634*V
0.0
= CF * ((V
+ 3*V
+ 3*V
0.0
0.2
= CF * ((V
+ 2*V
+ 2*V
0.0
0.2
= CF * Integrated velocity
76
SonTek – a Xylem brand
) / 4)
0.8
)
0.62
+ 2*V
+ V
) / 10)
0.6
0.8
1.0
+ 2*V
+ 2*V
+ V
0.4
0.6
0.8
1.0
) / 10)
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