K-values (horizontal and vertical), storage coefficients in the horizontal model or porosities for calculating the storage coefficient in the vertical or 3D model are data that must be defined for all elements. However, it is not possible to optimise a separate parameter for each element or node due to the computational effort involved. This data is therefore zoned.

The following model data types are provided for zoning these parameters:

• Z-KW parameter for zoning K values (KWER, KWE)

• Z-SP parameter for zoning storage coefficients (KSPE)

The zones are defined in the model data file. The zone numbers must be integers larger than zero. If some elements/nodes do not lie in a zone defined with Z-KW or Z-SP, an additional zone with the zone number 0 is automatically created during the model check, in which all elements or nodes not recorded lie.

There are three options within a zone:

• If a corresponding start parameter is defined in the parameter file for only one element/node of the zone, all elements/nodes of this zone receive this constant parameter value. In this case, it does not matter for which element/node of the zone this parameter was defined.

Only one parameter is optimized within this zone.

• If start parameters are defined in the parameter file for several elements/nodes in a zone, values are interpolated from these parameters (according to an interpolation algorithm to be selected) for all elements/nodes in this zone. Parameter values from other zones are not included in the interpolation.

Several parameters, namely those used for interpolation, are optimised within this zone.

• If a start parameter is not defined in the parameter file for any element/node of the zone, the corresponding data from the model file is used for the calculation.

No parameters are optimised within this zone. The fixed values for K values or storage coefficients from the model file are always used for the calculation (data types KWER, KWEV or KSPE).

If the values from the model file are to be saved for elements or nodes in a zone, no start parameter may be entered in the parameter file for this zone.

Conversely, if one or more start parameters are defined in the parameter file for certain zones, the data entered in the model file is irrelevant for the elements/nodes in these zones, as it is replaced by the calculated value during the optimisation run. If all elements/nodes are zoned and start parameters are defined for all zones in the parameter file, it is not necessary to enter K values or storage coefficients in the model files.

Zoning of leakage coefficients