10.4122/1.1000001476 Willems, P. Relative comparison of different types of uncertainties in sewer water quality modelling DTU Library, Technical University of Denmark (DTU) 2005 Modelling sewer emissions uncertainty water quality Katholieke Universiteit Leuven, Hydraulics Laboratory en Conference full text 10.4122/1.1000001475 application/pdf 1 Quantifiable sources of uncertainty have been identified for a case-study of integrated modelling of a sewer system with a more downstream wastewater treatment plant and storage sedimentation tank. The different sources were classified in model input and model-structure uncertainties. They were quantified and propagated towards the uncertainty in the prediction of sewer emissions (flow, and physico-chemical water quality concentrations and loads). Based on variance decomposition, the total prediction uncertainty was splitted into the contributions of the various uncertainty sources and the different submodels. Although the results strongly depend on the water quality variable considered, it could be concluded in most general terms that the uncertainty by the water quality submodels is an order of magnitude higher than for the flow submodels. Future model improvement should therefore mainly focus on water quality data collection.