Characterization of sources of microbiological contamination in the Seine River during the Paris Olympics 2024 using inverse modeling

Rivers provide many ecosystem services. However, in densely populated urban areas, they are polluted by multiple sources including combined sewer overflows (CSOs). By studying the behavior of the combined sewer system, whose capacity can be saturated during heavy rainfall episodes, it is possible to anticipate these contamination periods. In addition, by using an inverse method (quantifying causes from effects), it would be possible to determine the quantity of contaminants released by the CSO. In this paper, we present the design of the method on the study site of the Seine River, in Paris. The spatial extension of the combined sewer network is described by a directed graph. Temporal consistency is achieved through event definition. The use of these data for CSO assessment would make it possible to anticipate contamination and guide decisions to contain it.