50
ERDC/CRREL TR-02-14
Contour plots were generated by entering a file with XYZ survey coordinates
into Surface-Water Modeling System (SMS) software package and creating a
finite element mesh. The mesh geometry was incorporated into the coordinate
file, with the resulting file used as an input file to Techplot (Amtec Engineering)
visualization software. The vectors representing the average velocity vectors
were overlain on the elevation contour plots.
Velocity profiles were generated using open water velocity measurements
that were as close as possible to a station used in the ice survey. The coordinates
for the open water measurements were calculated by linear interpolation along
the cross section alignment using the reported offset from shore. If the boat used
to obtain the velocity measurement or the bottom elevation were out of align-
ment, an error could be introduced. Without repeatability in location, comparison
between the open water and the ice cover velocity profiles is difficult. Given
these limitations the comparisons are helpful in showing the shift in the velocity
profile.
In the plots the velocity was set to 0 at the waterice and watersediment
interfaces. To represent the open water depth, the surface velocity was set was
equal to the velocity measured at 0.2 of the flow depth .
Web cameras
Visual documentation of the ice conditions was important for identifying
changes in ice conditions that may have contributed to local changes in the river
channel, as well as for monitoring interactions between ice floes and channel
banks during ice cover breakup. Digital video cameras linked to a web site, or
web cameras, proved to be invaluable for these purposes.
The digital cameras and environmental housings were installed under the
bridge at the Culbertson site and attached to power poles at the Tveit-Johnson
and upstream and downstream areas at the Pipal sites (Fig. 32). Digitized images
were uploaded to CRREL via phone modems using a hardwired phone line at all
the sites, except at the remote Tveit-Johnson site, where a cellular phone had to
be used. The cameras and associated hardware were connected to 120-VAC.
power. Images were automatically displayed on the web site (www.crrel.usace.
army.mil/ierd/scour).
A further benefit of the web cameras was that the images could be assembled
to form a movie that animated the processes being monitored. A movie sequence
was developed for the Tveit-Johnson camera immediately following ice cover
breakup, showing the unstable bank collapsing into the river.
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