For several years now, urban stormwaters have been identified as a major cause of pollution, along with wastewater. Before listing the technical solutions, it is important to assess the quantity of the effluent and spills with sufficient precision.
These are the goals set for the FLUPOL model, developed jointly by Agence de l'Eau Seine-Normandie, Syndicat des Eaux d'lle-de-France and Compagnie Générale des Eaux. This model calculates the flow rates and discharges of Suspended Solids, BOD5, COD, and Kjeldahl Nitrogen downstream from an urban catchment and its drainage system after a given rainfall, without needing too complex and expensive data. The phenomena simulated range from accumulation of polluting matter on urban surfaces during dry weather to the transit of flow and pollution in the sewer, including possible deposition or resuspension processes.
The FLUPOL model was adjusted and subsequently validated using several series of measurements carried out in France, and has been used in several sewerage studies taking into account the polluting discharges during wet weather.
Considering flow rates and pollutant discharges, the difference between the calculated results and the measurements has always been less than 20 %. The model can then be applied in other drainage systems than those used for calibration and validation.