# High Discharge Value in SWAT modelling

At first run I’ve encountered the problem since the values of modeled and observed discharge are significantly different. The correlation between them is nearly 0,2 as the modeled discharge gives much higher values.
I have already checked the precipitation file (it has some missing values which I substituted with zeros) and also did the correlation between the discharge and precipitation which showed the result nearly 0,35; while the cross correlation with three-day lag is 0,6.
In addition, the model predicts the precipitation values very accurately, though the discharge is very high.
How can I identify what is the conceptual logic behind the algorithm of inflow-outflow calculations in SWAT (or maybe refer me to the literature on the matter) so I could go through the output again and identify the potential problem?