Model Parameter Adjustment

Is there an operator I can use to determine the position where the average value of a dependent variable (of a 2D geometry) will reach a particular value? To be clearer;

I have a three PDE that I am solving simultaneously, one of the dependent variables is porosity. My target is to determine the position along the length of the domain where the average porosity along the vertical axis of the domain reaches 1. I know that looking at the GUI I can see it after the study is computed. But I need this information to adjust one of the parameters of the model, if possible, before computing; as the adjustment is inherently coupled with the variation of the porosity distribution.

Thanks.

Femi Oyedokun