Defining pore water pressure boundary conditions

[yingying]

I am trying to model the pore water pressure in a dam with the upstream face submerged by the reservoir.

I know I can set the pore water pressure fixities, however so far I have only found this useful if I have a level water table - however in my situation, since there is a body of water on a side of the dam, how can I define them with a specific value of pore water pressure e.g. depth x 9.81?

I am trying to define the hydrostatic conditions so that I can model the pore water pressures at equilibrium within the dam.