A hydrological model to estimate pollution from combined sewer overflows at the regional scale: Application to Europe

Combined Sewer Overflows (CSO) of 671 Functional Urban Areas (FUAs) throughout the European Union + UK (EU28), representing almost half EU28 population. CSO loads can be quantified at local scale through measurements, or with calibrated hydrological models. However, they are difficult to quantify a large (e.g. regional national), due lack data, and models used cannot applied in absence knowledge combined sewer (CS) network. This paper presents 6-parameter lumped model simulate CS network its overflows, using population rainfall data FUAs. When properly calibrated, predict hydrographs as well aggregated descriptors catchment known impervious surface area connected reasonable reliability. calibration is not possible, default values parameters enables first approximation estimate CSOs, accurate within one order magnitude, which support scenario analysis for continental management. At scale, estimated total volume 5.7·103 Mm3/y, dry weather flow content CSOs 460 Mm3/y (assuming 200 l/population equivalent (PE)/day including sanitary discharges, industrial discharge infiltration). A collection case studies on also provided.