In the Parameter Estimation Process, parameters defined in the Groundwater Flow process and selected in the Sensitivity process are varied so as to minimize an objective function defined in the Observation process and with Prior Information equations defined in the Parameter-Estimation process input file.  Thus parameter estimation is used for model calibration.

Parameter-Estimation process input file

The Parameter Estimation Process is not included in MODFLOW-2005 or MODFLOW-LGR.  External programs such as UCODE must be used instead.