The Parameters tab is on the MODFLOW Hydrogeologic Units dialog box.
All the parameters for the Hydrogeologic Unit Flow (HUF2) package that are associated with hydrogeologic units are listed on the Parameters tab along with the parameter type. To use a particular parameter with a particular hydrogeologic unit, check its check box in the Parameters column of the table. To use a Zone or Multiplier array with a parameter check the corresponding check box in the table.
If Use Zone is checked in the MODFLOW Packages and Programs or Manage Parameters dialog boxes, a boolean data set will be created that can be used to determine where the parameter applies. The parameter will apply everywhere where the data set is true. The name of the data set will be the name of the parameter followed by "_Zone.." If Use Zone is not checked, the parameter will apply everywhere.
If Use Multiplier is checked in the MODFLOW Packages and Programs or Manage Parameters dialog boxes, a real-number data set will be created that can be used to determine how the parameter Value is related to the input. The name of the data set will be the name of the parameter followed by "_Multiplier." The parameter value will be multiplied by the values in the multiplier data set for each cell to determine the input value for MODFLOW at that cell.
If more than one parameter of the same type applies to the same cell, the input value for MODFLOW will be the sum of the input values determined for that cell for all the parameters that apply to the cell. For example, suppose that there are two HK parameters defined: HK1 and HK2. They have Values of 10 and 20 respectively. If they both apply to the cell in column 1, row 1, layer 1 and neither has multiplier data sets, the hydraulic conductivity for that cell would be 10 + 20 = 30. Now suppose that the multiplier for HK1 was 5 at that cell. The hydraulic conductivity for that cell would be 10*5 + 20 = 70.
Additive parameters are not allowed for VANI parameters.