EEMS provides the user with a number of options for continuing a model run that has stopped prematurely for some reason, or if it has crashed. These include Continuation runs for carrying on from where the model ended, and Restart, for carrying on the run from another time earlier in the run. The EFDC Restart Options are contained in Timing / Linkage in the Model Control form. After a right-mouse click on the Restart Options, the EFDC Model Restart Options form is displayed as shown in 240222401Figure 1. An explanation of the terms used, as well as how to use each option, is provided below in detail. Users of these features should be aware that they cannot change the model BC locations and type from the original model to the model using the restart file. Doing so may result in flows going to the locations in the model that no longer have a valid BC.
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A Cold Start is the default option for a model run. In this case, EFDC+ generates new output files or overwrites the existing output files (240222401Figure 2).
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Figure 2. EFDC Model Restart Options: Cold Start
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Restart is applicable when a model has stopped prematurely and has finished the run. The user can use it to restart from the point at which it terminated or some other point by selecting the appropriate restart file. In this case, there is a hard restart from the time selected. EFDC will create a whole new set of output files which the user will then need to merge later. 240222401 Figure 3 shows the Restart option.
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The Continuation feature allows the model to begin writing from the exact time where it stopped or from the time selected for restart in case of using date stamp. The settings for this option are shown in 240222401Figure 4.
The Continuation is the same as the Restart option except that the output will be appended to an existing run and so is only applicable when there is already model output in the current model directory. If there is no output and a restart file then this option is not enabled. If no date stamp is used EE will display only one restart file without a date label which is the last restart file before EFDC terminated. To create the restart file the Restart Output should be set to continuous (i.e. N=1). EE displays the date range available for the continuation from the most recent binary file output in the Last Datebox.
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- Before running the model ensureOutput Options for Restart Files is set/checked to Use. If Date Stamp is selected the user may continue from any snapshot as all snapshots are saved, not just the final snapshot. However, this is more memory intensive.
- Reload the model to update Last Date box. In this case the model stopped at T = 218 (Figure 4).
- Select the Continuation radial button (this is not enabled if the model is not reloaded). A warning message will be displayed as shown in 240222401 Figure 5.
- Do not change the time of the start. Save the model in the same folder. If the user wants to save in another folder then they will need to manually copy the output to the new folder.
- Run the model and select overwrite.
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Once the Restart Options is selected, it will be updated to the Model Restart Options report as shown in 240222401 Figure 6.
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Figure 6. Model Restart Options Report
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The Output Options for Restart Files frame (240222401Figure 7) provides options for the creation of restart files. If the Use option has been selected then EFDC+ will create a RESTART.OUT file automatically. If Date Stamp is not checked then one file called RESTART.OUT will be created at the user-defined Output Frequency, overwriting the previous file each time. If Date Stamp is checked then a file called RESTART_YYYYMMDD_HH.MM.OUT is created at the Output Frequency for each EFDC+ sub-module utilized.
It is standard practice to always select Use and then set Output Frequency to 1 to be the same as the duration of the reference periods. The user must have this option turned on in order to use restart as this creates the files required for the restart. The Date Stamp can be left unchecked so that the file is written over each time it outputs.
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Figure 7. Output Options for Restart Files
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