User's guide of Proceessing Modflow 5.0

44 Processing Modflow
Three steps are required for an automatic calibration.
1. Assign the zonal structure of each parameter.
Automatic calibration requires a subdivision of the model domain into a small number of
reasonable zones of equal parameter values. The zonal structure is given by assigning to
each zone a parameter number in the Data Editor.
2. Specify the coordinates of the observation boreholes and the measured hydraulic heads.
3. Specify the starting values, upper and lower bounds for each parameter.
< To assign the zonal structure to the horizontal hydraulic conductivity
1. Choose Horizontal Hydraulic Conductivity from the Parameters menu.
2. Move to the third layer by pressing PgDn twice.
3. Choose Reset Matrix... from the Value menu (or press Ctrl+R).
A Reset Matrix dialog box appears.
4. Enter 1 to the Parameter Number edit box, then click OK.
The horizontal hydraulic conductivity of the third layer is set to the parameter #1.
5. Choose Leave Editor from the File menu or click the leave editor button .
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 we are actually calibrating the transmissivity and must use suitable values for the
initial guess and lower and upper bounds. Change the layer type to 3:confined/unconfined
(transmissivity varies), if you want to calibrate the horizontal hydraulic conductivity.
< To specify the coordinates of the observation boreholes and measured values
1. Choose Boreholes and Observations from the Parameters menu and enter the
coordinates of the observation boreholes into the boreholes table.
2. Click the Observations tab and enter the values into the observations table as shown in
Fig. 2.36. Note that the observation time, to which the measurement pertains, is measured
from the beginning of the model simulation. For a steady state simulation with one stress
period (you can run a steady state simulation over several stress periods), the length of the
period (9.46728E+07 seconds) is given as the observation time.
3. Click OK to close the dialog box.
2.3 Automatic Calibration