Material property dependent on solution variable

Hi,

I'm trying to solve a 1D flow problem with Darcy's Law. The permeability of my material is supposed to be dependent on the pressure gradient in the medium. So I would first have to create a study to solve for the pressure gradient in the medium and then use the solution from the first study as an input to the second study, which calculates Darcy's law right? How would I go about setting up a study that only solves for the pressure gradient in the medium?

Thank you!
Alexandra