Visual MODFLOW Flex allows you to compare Heads or Drawdown between several model runs. This is useful to determining differences in pre- and post-pumping heads or comparing impacts to heads or drawdown when adjusting property or boundary condition parameters.
Follow the steps below:
•Right-click on the Heads node of any model run, and select the "Compare" option. The following dialog will appear
There are two options available:
•Select a Heads from the Output tree from another model run; in this case, click on the Heads node from another model run, and click on the button to add this to the field
•Select a MODFLOW .HDS file from the hard drive, from another model. Click on the Open folder button and browse to a .HDS file on the hard drive.
•Click OK. A new view will appear. The plot shows the results of subtracting the heads selected specified above from the Heads where you launched the `Compare Heads` option.
The same option is available for Drawdown. Just launch `Compare` from the Drawdown node on the Output model tree, and choose the Drawdown from another model run, or a .DDN file from the hard disk.
The comparison calculation has the following assumptions: Both models must have the same:
•start date (as defined in the Conceptual Model settings),
•spatial coverage (XY extents), and
•angle of rotation