90
ERDC/CRREL TR-02-14
1904
Oct-98
Jan-99
1902
Feb-99
1900
1898
1896
1894
1892
1890
Location: Downstream cross section approximately
in the middle (RM1632.55, Station 2+00)
1888
0
0.5
1
1.5
2
2.5
3
3.5
4
Water Velocity (ft/s)
Figure 65. Velocity distributions about mid-channel downstream at cross
section RM 1632.55 at approximately 200 ft from the right bank.
Mattelin site, RM 16451646
The morphologic complexities of this site, in which the river flows through
potentially three subchannels, appear to make the site especially sensitive to ice
cover formation. The complexities also complicate interpretation of river ice
influences because they make the site's response to ice formation dynamic and
thereby difficult to monitor.
Observations
The main influences of river ice at this site are essentially the same as those
observed at the Culbertson site; i.e., the way that an ice cover progresses
upstream through the site substantially determines which of the site's several
subchannels enlarges during winter and becomes the main thalweg. The Mattelin
site, though, seems to be more dynamic than the Culbertson site, in that changes
in subchannel size, bed elevation, and main thalweg alignment evidently hap-
pened quicker at the Mattelin site.
Figure 66 shows the Mattelin site before ice cover formation, following
freeze-up, during ice cover formation, and shortly after breakup. It also shows
how ice cover formation raised the flow stage through the site. Although cover
progression through the site was not viewed directly (there was no video camera
at this site), views of the site before, during, and after it became ice covered help