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The input file ISTAT.INP file is the same as early versions of EFDC for the ICECOVER.INP, with a timestamp and a status of ice cover. The convention is quite similar to that of other time series. The header contains the number of data lines, and time conversion coefficients. The remaining block includes two columns: Julian time and the status of ice cover, either 0 or 1, off or on. The ice temperature and the ice thickness are stored in EFDC.INP file in C46A and only used for display purposes.
Appendix B shows the format for this file. EFDC reads the file and applies it in the same way as ICECOVER.INP. All the other computations are the same as those for ISICE=1, except the initialization is the whole model on or off rather than based on the ICEMAP.INP file. EFDC can also handle multiple ice series and weights based on different series like NISER.
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When calculating ice formation in a river, if the air temperature is less than freezing temperature (a value that may be lower than zero in saltwater), generation of ice crystals takes place in the water. These crystals are called frazil flakes. As the frazil flakes are lighter than water, they float and cause "ice pans" which may then become "ice floes". As the frazil ice rises, it is necessary to input a rising velocity into EE to account for this.
In addition to the modification to the EFDC subroutines outlined for ISICE =3, a new routine, CALTRANICE, is created to simulate frazil ice as a concentration.
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