EFDC Restart Options are shown in Restart Options. An explanation of the terms used, as well as how to use each option, is provided below.
Figure 1. Model Restart Options.
Cold Start
Cold start is the normal start of a model run and EFDC will generate the new output files or overwrite the existing output files.
Restart
The Restart is a previously available feature of EFDC and is applicable when a model has stopped prematurely and not finished. The user can use it to restart from the point at which it terminated or some other point by selecting the appropriate restart file.
Continuation Run
A new option is Continuation, whereby when restarting a model, EFDC+ can now move to the correct location in the EE linkage files and begin writing from the time the model stopped or from the time selected for restart in case of using date stamp. The settings for this restart option are shown in Restart Options.
A Continuation Run is the same as the Restart option except that the output will append 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 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 Dates box.
The process for using continuation runs is as follows:
- Before running the model ensure EFDC Restart Options (Output) is set/checked to Use. If Date Stamp is selected the user may continue from any snapshot as all snapshots saved, not just the final snapshot. However, this is more memory intensive.
- Reload the model to update Last Date box.
- Select the Continuation radial button (this is not enabled if the model is not reloaded).
- Do not change the time of 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.
The model will run from the continuation time and automatically merge with the prior output. This removes the necessity of the user having to merge runs as was required in earlier versions of EE. This option is different to the Append feature as it is now possible to restart a model at various user-defined times.
Note: Whenever a new cold start is run the user should save the model in a new folder. This will prevent restart files from prior runs being available, in which case the Last Date may correspond to that prior run.
EFDC Restart Option (Output)
EFDC Restart Options (Output) checkbox provides options for creation of restart files. If the Use option has been selected then EFDC will create a RESTART.OUT file. 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 being utilized. Note that if Use is not checked it is not possible to create restart file should the model stop or crash for some reason.
DSI standard practice is to always select Use and 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. Date stamp can be left unchecked so that the file is written over each time it outputs.