The various observation packages in MODFLOW-2005 and related programs are used to compare observed values with simulated values. Such comparisons are useful in model calibration.
Head observations are compared with simulated heads interpolated to the location of the head observations. If the observed head represents more than one layer, a weighted average of the heads in the various layers is calculated.
Specified-head flow observations are compared with simulated flows at a group of specified head cells.
Drain observations are compared with simulated flows at a group of drain cells.
General-head boundary observations are compared with simulated flows at a group of general-head boundary cells.
River observations are compared with simulated flows at a group of river cells.
Stream observations are compared with simulated flows at a group of stream cells in the Stream (STR) package.
The Observation Utility in MODFLOW 6 is used to specify locations where heads, flows or other simulated properties are simulated. MODFLOW 6 will generate a file or files in which the simulated values of these properties are reported for every time step.
