Question about groundwater boundary condition

Dear EFDC users,

Good day!
I know that EFDC provides the groundwater boundary condition, but I was wondering when we should consider that condition.
Typically for river modeling, I used to set boundary conditions at the inlet/outlet and the simulated results were okay. I would like to know the reason or background on how we can simulate the river flow without the groundwater boundary condition, though groundwater discharge exists along the river in reality.

Thanks for your help.


I think the groundwater BC will be used if there is a significant groundwater recharge in your model domain.