How to simulate suction applied at bottom of column experiment

[waterislife]

Hello,

We ran column experiments were fresh water was applied to the top of a column filled with impacted soil. To induce drainage at the bottom of the column, variable suction was applied. The amount of suction over time was measured as inches of mercury. We also know the amount of water that drained over time and the concentration of drainage water at discrete intervals. Where in hydrus 1D would I put the time-variable suction? I have the lower BC set to Variable Pressure Head. Would I put the time variable suction in the GWL column of the time variable boundary conditions? Also, how would you advise I convert a pressure unit (inches of mercury) to something usable in Hydrus?

Thank you in advance for guidance you can provide.

[Jirka]

Yes, the GWL column.
Conversion: I would hope that you will figure this out yourself.
J.