YSI SonTek RiverSurveyor, System Manual

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SonTek/YSI Inc
RiverSurveyor System Manual (May 1, 2007)
50
3.11.2. How does Shallow Water Operation work with RiverSurveyor?
The shallow-water cell is displayed as an additional cell at the top of the velocity profile in Riv-
erSurveyor (
Figure 3-24
). Shallow-water cell data are used in the extrapolation of the vertical ve-
locity profile and provide more definition to the unmeasured region of water near the surface.
To enable/disable this feature, go to
User Setup | Advanced Settings
tab (
Figure 3-20
). Set
Shal-
low Water Operation
to
Yes
or
No
. When set to
Yes
, RiverSurveyor automates the use of the shal-
low-water cell in the velocity profile. This greatly reduces the configuration overhead and incor-
porates multiple acoustic Doppler processing methods without increasing the system complexity.
The key criteria for determining the validity of the cell are three or less standard cells and a
maximum relative (to the vessel) water speed of less than 1.0 m/s.
Figure 3-24
shows a portion of the contour graph. In this example, the shallow-water cell was
used when water depth was less than about 1.0 m. The shallow-water cell turned off automati-
cally for the remaining profiles.
3.11.3. Where should I use Shallow Water Operation with RiverSurveyor?
Shallow-water operation has the greatest benefit when used to better define the flow at the edges
of the river or in cross-sections where the maximum water depth is very shallow.
Conversely, in the center of a river where velocities are typically higher, shallow-water operation
is not used, as there is the potential for ambiguous velocities. In the deeper sections of the river,
the velocity profile is typically very well defined using the normal operating setup.
Figure 3-25
shows the shallow-water cell being used near the edges of the river (extreme left and
right areas of display), and automatically disabled in the deeper, higher flow section of the river.
Figure 3-25. Contour Graph shows shallow-water cells at extreme left and right of top row