Specific storage vs drain fillable porosity in unconfined

In the case of the unconfined model, we should specify the fillable porosity however specific storage option is not turned off. Does it mean it is still used by the model, maybe for the "fix" layers rather than the porosity ?

Cheers !

FEFLOW uses both storage parameters in unconfined solutions. In unconfined layers, however, drain-/fillable porosity will be way larger than specific storage. Please have a look at the corresponding equations in the Reference Manual (http://www.feflow.info/manuals.html) for details.

Thanks Peter, can you precise which documents / chapters indicates the formulas I should look at ?

See, for example, eq. 3-14.

Thanks Peter but sorry ... does equations doesn't speak a lot to me. Maybe should I reformulate my question: in the case of an unconfined aquifer overlaying a confined aquifer, how do you set up storage and drainable porosity ?

Thanks again for your great support.
Cheers!
Didier

I finally get into equations with the help of colleagues. Maybe the first step is difficult but finally it is very helpful. What we understood is that Feflow takes into account a combination of Sy and Ss, Ss being multiplied by a pressure related term. In my case I estimated that if Ss is under 0.001, it will be negligeable with Sy > 0.1, because the pressure term will be always less than 200 m of water. Is this something that seems reasonnable, without going into details ?

Thanks,
D