YSI SonTek RiverSurveyor, System Manual

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SonTek/YSI Inc
RiverSurveyor System Manual (May 1, 2007)
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have to cross in a straight line and can easily change direction and speed (gradually) without in-
fluencing the accuracy of the discharge data. This is a major advantage of a RiverSurveyor ADP,
particularly in strong currents.
The software computes the boat position using either bottom-track (§
3.3
) or GPS (§
3.4
) and cal-
culates the river discharge as the boat transects the river. In addition, because the ADP is rapidly
collecting three-dimensional data, it can easily account for complex flow patterns commonly en-
countered when making a discharge measurement (e.g., bi-directional flow, steep velocity gradi-
ents, reverse flow along the banks).
The surveying operation is very simple, and it typically takes only a few minutes to transect the
cross-section of a river. A similar operation carried out using present methods requires larger
crews, working long hours in potentially unsafe conditions, to obtain data at only a few profiles,
which then requires post-processing to determine discharge. This means that by using smaller
crews operating with a boat-mounted ADP, a much larger coverage of the river network can be
obtained while minimizing the exposure of personnel to unnecessary risks and hours of post-
processing.
In summary, using a RiverSurveyor for real-time river gauging has the following advantages:
•
Reduced crew sizes.
•
Reduced time to measure discharge in a river cross-section (from hours to minutes). This al-
lows for reduced variability between measurement runs.
•
Faster gauging means more measurements, thereby allowing larger areas to be surveyed
during a flood event.
•
Significant reduction in cost for any real-time operation (both in the field and for post-
processing).
•
Improved crew safety.
•
Instantaneous discharge calculations.
•
Improved data accuracy through continuous measurement of velocity profiles across the en-
tire river width.
•
Improved discharge ratings for a stream gauging station.
•
Correctly takes into account eddy flow on the calculation of discharge.
•
Simplified river gauging by removing the requirement for the vessel to be steered along a
fixed line.
•
Bottom track and/or GPS position input to correct data for boat velocity.