Deactivate elements in lower layers

[siminhydrus]

Hello,

I have a 3D model developed using HYDRUS 5.04.0230. The model consists of 30 layers, representing about 30 meters of the unsaturated zone and 6 meters of the saturated zone at the bottom. Is there any way to deactivate the lowest three layers, which correspond to the saturated zone, and apply a zero-head boundary condition at the fourth layer from the bottom without remeshing? For a particular scenario, I want to place my boundary within the capillary fringe and reduce simulation time by excluding the saturated zone.

I also have another question regarding the same model. A portion of the top layers in the middle of the domain consists of playa lakes, which act as recharge areas with increased infiltration during hydroperiods (inundation periods). As I understand it, defining a surface layer (ponding) is not possible in 3D models (I am currently using an atmospheric boundary condition at the top). I also tried to manually modify hCritS in the input file, but I noticed that it resets to zero every time I run the model. The inundation period can sometimes last for more than a month, with ponding depths reaching approximately 3 feet. During this time, the top soil should remain saturated. What would be the best alternative approach to simulate the inundation period in playas? Any suggestions would be greatly appreciated.

Best,
Simin

[Jirka]

We have in HYDRUS a command “Edit->FE Mesh->Remove Selected Elements” (also on the Edit Bar when FE mesh is displayed). You can use this command to remove selected elements (or layers, etc).

You may try the Boundary Conditions Options command: Atmospheric BC when the specified nodal pressure head is negative. This should allow you to assign ponding in some parts of the boundary (with positive pressure heads), while atmospheric BC is applied on the rest of the boundary (with negative pressure heads). The boundary pressure heads are adjusted based on the z-coordinate. h=h_bot+z.
J.