Each calculation requires at least the following data: The mesh must be defined; a transmissivity must be assigned to each element and a fixed potential head or a leakage boundary condition must be defined for least at one node so that the system of equations does not become singular. Margins without explicit specification of a boundary condition imply an inflow/outflow rate = 0.0.

There are several input options for defining the transmissivity of horizontal and vertical models, which can vary from element to element. The various options can be combined as desired, but only one input can be considered per element. Hydraulic conductivity, transmissivities and thicknesses with the value 0.0 are not permitted. The first two options are suitable for isotropic material:

1. K-values and thicknesses

K-values, the thickness is automatically calculated from the lower- and upper-boundaries (for a horizontal model).

2. Transmissivities with/without thicknesses or K-values

If no thicknesses are defined, these are set to a constant = 1.0 m to calculate the velocities.

3. Material data, zone numbers, thicknesses.

4. Material data, zone numbers, lower- and upper-boundaries (for a horizontal model

The combination of 4. and 5. Is suitable for anisotropic material. Each element is assigned a zone code. The material data (k_fx, k_fy, angle) is then assigned to the corresponding zone codes

5. K-values, lower boundaries and initial potential heads (horizontal model).

6. K-values, lower boundaries and ground level (horizontal model)