Point and diffuse loads of selected pollutants in the River Rhine and its main tributaries

This report describes a method for estimating the amount and fractions of pollutant loads from point and non-point sources. The method presented relies on the analysis of concentration-discharge and load-discharge relationships respectively, using the extensive monitoring data on the Rhine River and its tributaries given in water quality monitoring reports by the International Commission for Protection of the Rhine and the national Deutsche Kommission zum Schutz des Rheins vor Verunreinigung. The results are suitable for calibrating the runoff/chemical mobilization model, because they are obtained independently of the above-mentioned method. The method is relatively simple to apply. The quality of the results depends mainly on the scattering of the concentration-discharge/load-discharge relationship, and on the detection limits for some pollutants, e.g., cadmium. The spatial resolution depends on the density of monitoring stations within the catchment area, and the temporal resolution depends on the frequency of single measurements and the scattering of the relationship. The method used is described in detail and a summarized overview of the results regarding the estimation of point and non-point net loads of zinc, lead, cadmium, phosphorus, and nitrogen for different monitoring stations of the catchment area of the River Rhine and its main tributaries is given.