SonTek – a Xylem brand
FlowTracker2 User’s Manual (January 2019)
70
Figure 5:1 – FlowTracker2 Probe Orientation Relative to Stream Flow
f) When all station measurements are completed, the operator records the ending-
edge location and water depth.
g) The total discharge is the sum of all station discharge values.
Discharge Calculation Methods 5.1.2
The discharge calculation methods implemented in FlowTracker2 are based on
established methods that are documented in international standards and are widely used
by government agencies, hydrologists and hydrographers. The discharge calculation
methods were originally developed for current meter instruments. The FlowTracker2
makes use of the same measuring technique and for this reason the same calculation
methods can be used to determine the total discharge.
The methods implemented for calculation of discharge 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 FlowTracker2 supports several discharge calculating methods for calculating
discharge following the basic measuring technique outlined above.
• Mid-Section equation (see 5.1.2.1),
• Mean-Section equation (see 5.1.2.2),
• The Japanese equation (see 5.1.2.3).
Mid-Section Equation 5.1.2.1
The Mid-Section method is based on a measurement section that is divided into a
number of stations with panels created for each station across the section. The average
velocity of a panel is assumed to be equal to the average velocity in the vertical
calculated from the point velocity measurements made. The equation of the Mid-Section
method is given in Equation 5:1.
Sampling
Volume
Y
X
Probe
Coordinate System
Graduated Tag Line
Primary Flow
Direction
Mounting
Pin
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