Attribute:

OBER [meters above reference datum] (element wise) (horizontal models only)

The upper boundaries of the aquifer can only be used if the lower boundaries of the aquifer are defined for the same elements at the same time. This eliminates the need to enter thicknesses for these elements. Upper aquifer boundaries are used together with the lower aquifer boundaries to determine the current and maximum thicknesses.

The attributes thickness, lower- and upper aquifer boundaries data types can be used simultaneously in a model. However, for each element only one thickness can be specified. The value is assigned using the unit [meters above reference datum] to each element. For 3D models, an upper limit can be defined by creating an additional layer with very low hydraulic conductivity.