Effects of land use changes on the nutrient balance in mesoscale catchments

Regional land use changes influence a great number of landscape functions. Simulation models can be used to evaluate the effects on water and nutrient balance. In this study the hydrological model SWAT-G was applied to quantify these effects. After a modification a calibration and validation was carried out. Based on the reasonably good reproduction of the measured values by the simulation, the model was applied to different scenarios with a sequence of land use change and thus, due to compensating effects in a complex structure of a real catchment, the effects of the land use change on the sediment yield were rather small. No trend could be depicted that it was altered by land use change, as neither forest nor grassland lead to higher erosion rates. Both forms of land use differ very little in this aspect. In contrast, a clear trend could be depicted for nitrate. With increasing deforestation and land use intensity the nitrate output increases, too.