flopy MF6, how to use saverecord as "STEP" or "FREQUENCY" in with fp.mf6.ModflowGwfoc()

[valDallalba]

Describe the bug

I encounter an issue when trying to save head or budget outputs for a defined time_step array or at a defined frequency when using the flopy.mf6.ModflowGwfoc() method. I'm using the flopy version : '3.3.6'.

I tried for a simple simulation, composed of two periods as follow :

tds = flopy.mf6.ModflowTdis(sim,  pname="tdis",   nper=2,   perioddata=[(1,1, 1.0), (100.0, 100, 1.0)])

The idea is to not record at each time step of the second period but only on some defined time step.

I did not find any tutorial or example using this method to save the output at a defined time step or at a define frequency. This seems to previously work with the method flopy.modflow.ModflowOc() where a dictionary of stress_period_data could be provided. However, when using the flopy.mf6.ModflowGwfoc() and defining my saverecord as "STEP" or "FREQUENCY" it seems that it is missing an argument or a keyword to specify the list of time steps or the frequency integer for which to save the head output.

My code looks like this :

oc = flopy.mf6.ModflowGwfoc(gwf, head_filerecord=head_path,  budget_filerecord=budget_path,  saverecord=[['head','step']])

And this is the returned error message :

KeyError: 'steprecord'

I would like to know if the help file of the method is missing an argument description or if I miss-understand the way to create the saverecord argument.

I have tried to add different arguments to the function or to create the saverecord argument in different ways, with for example an array instead of the keyword, but nothing seems to work for now. If anybody has some idea for how to specify the list of the time step for which to record the output that would be really helpful.

Cheers!

Val

Desktop (please complete the following information):

• OS: Ubuntu 18.04.5 LTS
• Browser : Firefox
• Version : Firefox -> 105.0 (64 bits), flopy-> 3.3.6

[langevin-usgs]

Here is an example of a valid saverecord, which you can pass to ModflowGwfoc. In this case you pass a dictionary where the key is the stress period number.

saverecord={0: [("HEAD", "FREQUENCY", 5), ("BUDGET", "FREQUENCY", 5)]}

It might also take:

saverecord=[("HEAD", "FREQUENCY", 5), ("BUDGET", "FREQUENCY", 5)]

I think STEP should work similarly.

[valDallalba]

Thank you it works perfectly.

Maybe just for other people that might encounter the problem, the syntax to get multiple time steps outputs is the following (which, at first I found a bit strange) :

saverecord=[("HEAD", "STEPS", 1, 5, 6, 7, 10)]

Thanks!

[langevin-usgs]

I believe you can pass multiple time step values when using step. I think the syntax is something like this:

saverecord=[("HEAD", "STEPS", 1, 3, 4, 9), ("BUDGET", "FREQUENCY", 5)]