Xylem SonTek FlowTracker2, User Manual

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SonTek – a Xylem brand
FlowTracker2 User’s Manual (January 2019)
69
Data Collection Modes Section 5.
The FlowTracker2 provides two data collection modes that the user can apply in the
collection of velocity data. The Discharge and General modes available in FlowTracker2
has different field applications and the method of each mode is described in this section.
5.1. Discharge Mode
Discharge Mode is for applications where the primary goal is to measure river/stream
discharge. The technique involves taking a series of velocity measurements at different
locations throughout the cross section. These measurements are combined with location
and water depth information to compute the total discharge.
Measurement Technique 5.1.1
The basic Measurement Technique used for performing discharge measurement using
the Discharge Mode is briefly discussed under the following points and this
measurement process should be read in conjunction with
Site Selection Requirements .
a) A measurement site is selected based on criteria stipulated in Site Selection
Requirements . The site selection process is a crucial part of collecting discharge
measurement data.
i). Ideal measurement site, the flow should be perpendicular to the tag line at all
points with no flow reversals or obstructions.
ii). The measurement site should encompass the minimum measurement site and
hydraulic requirements discussed in Site Selection Requirements .
iii). Flow conditions at the measurement site are the most important factor in
determining overall accuracy of the measurement.
b) A graduated tag line is strung across the river.
c) The operator starts at one edge, recording the starting-edge location and water
depth.
d) The river cross section is split into several stations. At each station, the operator
records the station location and water depth, and then performs velocity
measurements at one or more depths to determine the mean velocity at that
station.
e) During velocity measurements, the probe’s X-axis is maintained perpendicular to
the tag line ( Figure 5:1 ); the red band (receiver arm #1) should face downstream.
Only the X-component of velocity (
Vx
) is used to in the discharge calculation,
regardless of the flow direction (flow direction is also measured and recorded).