Simulation of the soil water balance on the “Intensive Loam Site”

A modified version of the model SWATRE was used to simulate the water balance of the “Intensive Loam Site” within the years 1989, 1990 and 1991. The data set from a north German catchment was used to set up the model and to compare the simulation results with field measurements. Additionally some input parameters necessary for the model had to be estimated. The goodness of the model results was quantitatively analysed by using the relative geometrical mean error and the standard deviation of the mean percentile error. The model was calibrated for the year 1989. The years 1990 and 1991 were taken for model validation. The data set proved not to be sufficient for a validation in a strict sense. The calibrated model showed a reasonable good coincidence with the observed data, although some distinctive differences could not be equalised. In these cases preferential flow or lateral fluxes are assumed to be responsible. However, both factors cannot be handled by the model. Considering the statistical distribution of the input parameter a and n the minimum range of the calculated data is shown.