The Richards’ Equation Model node defines the storage and retention models in variably saturated porous media. See the Unsaturated Porous Medium described for The Richards’ Equation Interface.

Note that for the Layered Darcy’s Law interface, the Fluid Properties and the Matrix Properties are defined on the boundary instead of the domain.

In the Shell Properties section you determine on which layer the Richard’s Equation Model is active. If you clear the Use all layers checkbox, you can select individual layers within one layered material. To specify different settings for different layered materials or for different layers, you have to add one boundary node for each layered material or for each layer, respectively. See also the Shell Properties section of the parent interface for more information.