Philipp Huttner

If I understand you correctly, you don't want to focus on the processes of the vadose zone, you have a high depth to phreatic surface (long distance between topography and groundwater table) and therefore want to reduce the computational effort for the UZ module:
1. option: apply the Gravity Flow for UZ (doesn't consider capillary rise) and make big numerical parameters for the solver, then it will run quickly
2. option: even faster, use the very simple 2-Layer UZ approach

Since the strength of MIKE SHE is the focus on surface-near hydrological processes, there is no simpler approach, like a gradient boundary condition.

I cannot directly give you the reason, but it seems to me that the tool grd2mike is having problems with longer file paths. If I copy the asc file to C:temp/file.asc, I don't get the error anymore.