Geo-referenced Regional Exposure Assessment Tool for European Rivers (great-er): a Case Study for the Rupel Basin

In the GREAT-ER project (Geography-referenced Regional Exposure Assessment Tool for European Rivers), an accurate aquatic exposure prediction tool for chemicals was developed and validated for use within environmental risk assessment schemes. In this paper, the application of the GREAT-ER methodology to the Rupel basin in Belgium is presented. Spatial concentration patterns of the anionic surfactant Linear Alkylbenzene Sulphonate (LAS) were predicted for this basin. Different scenarios were simulated. LAS removal in waste water treatment plants is high (98-99.9%). However, since only 30-40 % of the wastewater in the Rupel basin is treated, predicted environmental concentrations (PECs) are high. For some subbasins, calculated PEC-values were positioned against biological and physico-chemical water quality measurements. This case study showed the feasibility of implementing a new large catchment on a short term and indicated which efforts are required to apply GREAT-ER on a large, ultimately pan-European scale. It was found that it is possible to simplify the river network without considerable loss of accuracy. This allows to gain time and reduce effort.