Modelling faecal contamination in the Scheldt drainage network

This study developed a model simulating the seasonal and spatial variations of microbiological water quality (expressed in terms of Escherichia coli concentrations) in rivers. The model (SENEQUE-EC) consists of a microbiological module appended to a hydro-ecological model describing the functioning of the entire Scheldt drainage network. The microbiological module describes the sources of E. coli, their transport and the processes responsible for the fate of E. coli once released into the natural environment (mortality, settling and resuspension). This model differentiates the dynamics of three types of E. coli: free-floating E. coli, E. coli attached to suspended solids in the water column and E. coli present in sediments. The model was verified by comparison of its results with temporal and spatial distributions of field data in different stretches of rivers of the Scheldt drainage network. It was then used to test various scenarios involving diverse modifications in wastewater management, which was shown to be the most determining factor of microbiological water quality. Due to its low temporal resolution, the SENEQUE-EC is poorly adapted to describing the microbiological quality in areas under tidal influence. Therefore, the data of the SENEQUE-EC model were used as upstream boundary conditions to run a microbiological model with a high temporal resolution devoted to the tidal Scheldt River and Estuary (the SLIM-EC2 model).

► We modelled microbiological water quality (Escherichia coli concentrations) in rivers.
► The model was applied to the rivers of the Scheldt drainage network.
► The predictions of the model were validated by comparison with field data.
► The model was used to test scenarios of wastewater management on water quality.
► Model data were used as boundary conditions to run a model of the Scheldt estuary.