SWAT-MODFLOW with smaller MODFLOW domain & QSWATMOD problem

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iste G

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Oct 21, 2025, 5:46:15 AMOct 21
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Hi everyone,

 

I've meet some problems while setting my model and using the QSWATMOD2.

 

1.     MODFLOW domain is smaller than the SWAT catchment

My study area requires a detailed groundwater MODFLOW model only for a critical sub-region. This means my MODFLOW grid is inside the overall SWAT catchment area.

What will happen? Will the model produce an incorrect water balance because the regions outside the MODFLOW domain are not properly receiving or exchanging groundwater data calculated by SWAT?

If some data error will happen?Are there any solutions without expanding the MODFLOW domain or reducing the SWAT area?

 

QSWATMOD2 problem

 SM1.PNG

When I select 'No', the simulation fails. When I select 'Yes', the simulation runs successfully. Why does this situation happen?

 

Any advice would be  helpful. I can provide more details if needed.

 

Thanks in advance!

Best regards,

James

Seonggyu Park

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Dec 16, 2025, 10:55:55 PM (22 hours ago) Dec 16
to SWAT-MODFLOW
Hi James,

There will be no groundwater–surface water interaction in areas where they do not overlap. However, in SWAT areas that do not have a MODFLOW grid, the groundwater module in SWAT will still be simulated.
Regarding the activation option, does the model crash without running any simulation? If you would like to run only the SWAT simulation for now, please use the SWAT binary file while I check the code on my end.

Best,
Seonggyu
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