The Water Framework Directive asks all EU member states to monitor and identify long-term trends in pollutant concentrations in order to improve water body states and secure water quality. For instance, Germany implemented threshold values of average total nitrogen concentrations for rivers flowing into North and Baltic Sea in its national law. Thereby, nitrogen and phosphorus being the most prevalent monitored water quality parameters.
The aim of the thesis is to perform statistical analyses on a nationwide dataset of N and P concentrations from water quality and discharge measurement stations. Major interest lies on the question if decreasing concentrations of N and P could be observed in the watersheds over time during the observation period (2006-2018). Analyses will involve also seasonal and discharge-related patterns as well as the relation of observed concentrations to the prescribed threshold values.