Figure 3. Structure of the ICETHK model

Original

HEC-2

T95 file

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.

thickness and roughness of the equilibrium ice

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-

input file.

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

5