In contrast to the calculation according to Schroeder and Wyrwich or Meßer 2008 after clicking on the menu item "recharge rate calculation":
a further input window opens:
In the input window the name of the file with the transient climate data has to be entered.
When activating the button "Average values, elementwise" the middle ground water recharge (FLAE) is calculated for each element.
When activating the button "hydrographs, averaged over" the transient data for every x days is generated, averaged over the interval groundwater recharge rate for each element.
The transient values are stored internally during the computation process, and can be exported to a transient input file via Special Features 
Transient Export transient input file....
When activating the check box, a file with user-specific soil parameters can be specified. Otherwise, the file "bopa.txt" with the default values is considered in the calculation.