User's guide of Proceessing Modflow 5.0

140 Processing Modflow
Note that for layers of type 0:confined and 2:confined/unconfined (transmissivity=const.),
MODFLOW reads transmissvity (instead of hydraulic conductivity) from the model data file.
Consequently, you are actually calibrating the transmissivity value as an estimated parameter
defined within horizontal hydraulic conductivity. For multi-layers model, MODFLOW requires
vertical leakance (instead of vertical hydraulic conductivity, which is used by PMWIN to
calculate the vertical leakance for MODFLOW). Due to this fact, automatic fit of vertical
hydraulic conductivity cannot be done without modifying the inverse model or MODFLOW. So,
if you assign an estimated paramter within vertical hydraulic conductivity, you should keep in
mind that you are actually calibrating the vertical leakance between two layers (the layer with the
estimated parameter and the underlying layer).
Table 3.7 Adjustable parameters through an automatic calibration within PMWIN
Parameter or excitations
3.6.5 PEST (Inverse Modeling)
Layer types 0 1 2 3
Transmissivity yes no yes no
Horizontal hydraulic conductivity no yes no yes
Vertical leakance yes yes yes yes
Specific yield (only if the simulation is transient) no yes yes yes
Confined storage coefficient (only if the simulation is transient) yes no yes yes
Pumping or injection rates of wells yes yes yes yes
Conductance of drain, general-head boundary, river or stream yes yes yes yes
cells
Recharge flux yes yes yes yes
Maximum evapotranspiration rate yes yes yes yes
Inelastic storage factor (only if the simulation is transient and the yes yes yes yes
Interbed Storage package is used)
PEST (Inverse Modeling) < Parameter List...
The required inputs and options for the PMWIN/MODFLOW/PEST interface are specified in
the List of Calibration Parameters (PEST) dialog box (Fig. 3.53). The avaliable settings are
grouped under five tabs described below. Using the Save... or Load... button, you can save or
load the settings.
< Parameters: The table gives an overview of the initial values and properties of each
estimated parameter. The meaning of each column of the table is describen below.
- Number: While editing a certain aquifer property or excitation, you have the option to