Xylem SonTek FlowTracker2 - Table 5:2 - Determining Mean Station Velocity

SonTek – a Xylem brand
FlowTracker2 User’s Manual (January 2019)
76
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 5:2.
Table 5-2 - Determining Mean Station Velocity
Method
Measurement Depth
Mean Velocity Equation
0.6 0.6 * depth
V
mean
= CF * V
0.6
0.2/0.8
0.8/0.2
0.2 * depth
0.8 * depth
V
mean
=
CF *
((V
0.2
+ V
0.8
) / 2)
.2/.6/.8
.8/.6/.2
0.2 * depth
0.6 * depth
0.8 * depth
V
mean
= CF *
(
(V
0.2
+ 2*V
0.6
+ V
0.8
) / 4)
Ice 0.6
0.6 * effective depth
V
mean
= 0.92*V
0.6
(Correction Factor 0.92 can be changed by user)
Ice 0.5
0.5 * effective depth
V
mean
= 0.88*V
0.5
(Correction Factor 0.88 can be changed by user)
Ice 2/8
Ice 8/2
0.2 * effective depth
0.8 * effective depth
V
mean
=
CF *
((V
0.2
+ V
0.8
) / 2)
Kreps 2-
Kreps 2+
0.0 (near surface)
0.62 * depth
V
mean
= CF *
(
0.31*V
0.0
+ 0.634*V
0.62
)
5 Point+
5 Point-
0.0 (near surface)
0.2 * depth
0.6 * depth
0.8 * depth
1.0 (near bottom)
V
mean
= CF * ((V
0.0
+ 3*V
0.2
+ 3*V
0.6
+ 2*V
0.8
+ V
1.0
) / 10)
6 Point+
6 Point-
0.0 (near surface)
0.2 * depth
0.4 * depth
0.6 * depth
0.8 * depth
1.0 (near bottom)
V
mean
= CF * ((V
0.0
+ 2*V
0.2
+ 2*V
0.4
+ 2*V
0.6
+ 2*V
0.8
+ V
1.0
) / 10)
Vertical
Velocity
Curve
Any number of points at
user-specified depths
V
mean
= CF * Integrated velocity
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.