Imod coupler crashes when using init_svat.inp computed from a run of a previous year:

[sebmeng]

Hello Community!
I have a question regarding the use of the iMOD Coupler. I want to run a coupled model with MODFLOW 6 and MetaSWAP, using a transfer function based on a previous long-term run (I don't need to create the transfer function). Additionally, I would like to run batch simulations per year, using the results of the previous year as initial conditions for the next year's run.
First. a one-year run was performed, and the information of the last time step was stored as initial conditions for the following run:

The problem if I use this as initial conditions for my next run, the Imod coupler crashes at time step 2:

but if I use as initial condition the original INIT_SVAT.imp for this new year:

The coupler runs without problem:

I would really like to use the output of the previous year run as initial conditions for my metaSWAP part of the second year.
Do you know if this is possible? Maybe I have a mistake somewhere, any guidance is appreciated 😄

[Huite]

Hi @sebmeng,

I'm pinging @HendrikKok, who currently knows MetaSWAP best in our team.

[sebmeng]

Thanks @Huite
Looking forward to check what could be the issue

[HendrikKok]

Hi @sebmeng

I had the same kind of issue reported by someone else. It seems to be an issue in the MetaSWAP-kernal. You should be able to start with initial conditions generated by a previous run.

What you could check yourself is that you start the new MODFLOW run, with initial heads that match the timestep that produced the init_svat-file for MetaSWAP. This MetaSWAP init_svat-file contains the combination groundwater level - pressure head. In the first timestep, first iteration, the MODLFOW initial groundwater levels are exchanged. This could lead to an error if these differ strongly from the ones read from the init_svat-file.

If this is ok, you model should run. If this is not the case: could you send me your model via hendrik.kok@deltares.nl. I don’t need the MetaSWAP-database and meteofiles.

[sebmeng]

Thanks for the reply @HendrikKok !
To compare the modflow initial heads with the groundwater level-pressure head in the init_svat.inp, which column shall I use to compare?

column 1 contains the node number and the second column is GWL-pressure head)?

[HendrikKok]

I think it’s enough if you check that you use the heads output of the previous run as initial conditions for the new one. In that case the init_svat-file and init MF-conditions should be aligned.