# Usage in PCRCalc¶

This chapter describes the usage of the PCRaster Modflow extension. The first step is to create one single extension object in the script’s inital section:

initial
...
# Construct Modflow extension object
object mf = PCRasterModflow::initialise();


This will initialise the data structures used in the extension. All operations described in the package sections will refer to the object mf.

Warning

Operations specifying Modflow input data currently return a boolean map containing false values, this behaviour may change in the future. It is strongly recommended to keep the coding style as shown below (i.e. res = mf::operation();) and advised not to use the result in oncomming operations.

The next step is the grid specification using the operations described in the DIS package. This must be done before any other package is defined. Afterwards packages can be defined in arbitrary order. For a Modflow simulation at least the DIS, BAS and BCF package must be specified.

The DIS, BAS, BCF and a solver package must be set in the initial section of a script. Stress packages (RIV, DRN, RCH and WEL) can be activated and modified in the dynamic section.

The differences of Python operations to the PCRcalc syntax is minimal and therefor only brief explained: The Python extension operations have the same name and take the same arguments as the PCRcalc operations. Setting for example boundary values in Python is done by

mf.setBoundary(boundaryValues, LAYER)


and in PCRcalc by

res = mf::setBoundary(boundaryValues, LAYER);


where boundaryValues is either a string holding a filename to a spatial, scalar PCRaster map or a variable holding an object returned by the readmap operation.

See the PCRcalc example script for further operations.