hydraulic head vs ground surface

Hi all,
I-m a beginner and I have some problems.
My real aquifer is unconfined but I'm working with feflow with the confined option (because is easyer for me and the numerical effort for my pc is lower), saturated condition, and steady state flow.
I have a question for you. After I run feflow, the obtained hydraulic heads distribution, in some areas of my domain, are higher than the ground surface.
It is not possible in the real hydrogeologic setting because my aquifer is unconfined and the water table has to be below the ground surface.
How I can constrain my final numerical solution (hydraulic head distribution) to be below the ground surface?

thank you very much

The hydraulic head distribution is a result of all the input parameters you have put. There is no possibility to constrain this - FEFLOW will show exactly what it calculates. You will probably have to calibrate your model, adapting your input parameters so that the model calculates realistic hydraulic heads.

I have a question about a similar topic.

I'm modeling a shallow aquifer in Venice lagoon, that is characterized by tidal oscillations of about 1m of amplitude. I treated the region occupied by sea as an aquifer with very high hydraulic conductivity (10 m/s), storativity = 1.
In the first slice I set a 0 m a.s.l. elevation for the part of the mesh occupied by sea, and obviously ground elevation for the part occupied by land.
Does this abrupt discontinuity in z elevation bring any computational problem for FEFLOW?
Another question: is it a problem, if levels are higher than z elevation in the first slice (e.g. during high tides)?

Kind regards,
Alessandro Casasso
PhD student - Politecnico di Torino