It is assumed that the storage capacity and storage coefficient of the upper ground water storage are lower than the lower one. This is so due to the fact that the storage in the lower zone represents the saturated groundwater aquifer with longer residential times. These values are difficult to acquire as they cannot be directly measured.
Schwarze (1999) provides recession constants and volumes of the lower ground water storage for different types of hydrogeological formations (Figure below). The information provided on this publication could be very instrumental in deriving the parameters values of a catchment for users.
A sample parameter file for different geological formations of Thuringian catchment is provided as a example.
After setting up the model file, you may wish to change the values (storage and recession coefficient) and observe their influence on hydrographs. This might provide ideas about the sensitivity of these values in model results.