Performance of the model SIMWASER in two contrasting case studies on soil water movement

The performance of the water balance and crop growth model SIMWASER to estimate either the capillary rise from shallow groundwater or the N leaching from a deep soil profile was demonstrated using measurements on the one hand from the Berlin-Dahlem lysimeter station and on the other hand from the Bad Lauchstadt experimental field. In case of the Berlin-Dahlem data, the robustness of the model was evaluated by running it either with measured hydraulic soil parameters or with estimated pedotransfer functions (PTF) derived from texture class, bulk density class, and humus content class. Simulations were performed for the period from March to September 1997. Simulated capillary rise and actual evapotranspiration (AET) deviated by less than 10% for both the measured and the estimated hydraulic soil characteristics, showing somewhat better results for the sandy soil. Nitrogen leaching from the deep Chernozem soil at Bad Lauchstadt is estimated for a bare and a cropped experimental plot from measured Nitrogen concentration of the soil solution and simulated percolation flux at 170 cm depth. Because of low N concentration at both plots, the amount of N leached down to groundwater during the investigated period from the beginning of 1999 to the end of 2002 was limited to 7 kg/ha at the bare plot and to 0.5 kg/ha at the cropped site.