Figure 3. Structure of the ICETHK model. Square-cornered boxes indicate programs and
subprograms. ICETHK subprograms lie within the large dashed-line box. External files
(both input and output) are indicated by round-cornered boxes.
The subprogram RUFCALC calculates the ice
accumulation are calculated.
roughness as a function of accumulation thick-
If water-current velocity is greater than the
ness. If floodplain flow depth is greater than
threshold velocity for thinning (VEROS), ICETHN
a user-defined threshold value, the process
calculates thinning of the ice accumulation, as
described in the previous paragraph is repeated
previously described. After checking if juxtapo-
to calculate ice thickness in the overbank areas.
sition is possible, thickening due to juxtaposition
Finally, the subprogram NEWDAT inserts the
is found in the JUXT1 and JUXT2 subprograms.
resulting ice data into the appropriate IC lines
The SHOVE subprogram then calculates the shov-
of the original HEC-2 input file, creating a new
ing thickness of the accumulation and the subpro-
gram JAMSEL selects the greater of the shoving
ICETHK contains the additional subprograms
and juxtaposition thicknesses. ICETHK uses the
DATCHK, WDSMOOTH, ICEVOL, ICESMTH,
thickness of the initial (parent) ice cover as a mini-
ITDAT, QP, FINAL, and PROFILE. ICETHK also
mum. This means that the cover cannot thin be-
creates and uses a number of external files for data
yond the parent ice thickness. It also means that,
output and for data storage between iteration
if a solution is not possible by juxtaposition or
cycles. The purpose of these additional subpro-
shoving, the parent ice thickness will be used.
grams and the external files will become clearer