Simulated future changes of extreme nutrient loads in a mesoscale agricultural watershed in Bavaria / Simulierte zukünftige Änderungen der Extremwerte für Nährstofffrachten in einem mesoskaligen landwirtschaftlichen Einzugsgebiet in Bayern

The hydrological model SWAT was applied to the upper Altmühl watershed to examine the simulated 10^th and 90^th percentiles of streamflow, nitrate nitrogen (NO₃^--N), and total phosphorus loads (TP), using an ensemble of reference climate (1975–2000) and future climate (2046–2070) simulations. A comparison between the two periods showed that in the future, the 90^th percentiles of the NO₃^--N loads increase in all seasons which indicates a trend to increasing diffuse pollution in the mid-term future. Conversely, the 90^th percentile TP loads diminished in winter and otherwise remained similar to the reference period. The 10^th and 90^th percentile changes in the future streamflow followed changes in precipitation, and did not have any apparent influence on extreme nutrient transport events.