DEVELOPMENT OF A PROPAGATION MODEL TO DETERMINE THE SPREAD OF ACCIDENTAL POLLUTION IN RIVERS

Pollutant spread in rivers is affected by numerous complicated phenomena, and only through modelling such spread is it possible to predict the concentration of solutes at strategic points along the river in case of accidental water pollution and to set up appropriate procedures to limit undesirable effects. The BRGM (Bureau de Recherches Geologiques et Minieres) has developed such a model to simulate the behaviour of any pollutant spilled into the surface water network and has integrated it in the ''SeauS' (SOS Water) software package designed by the BRGM to help reach a decision in matters of water protection. The model is based on the ''mixing cells'' method which has a high execution speed and is suitable for simulating the various flow mechanisms occurring in rivers; i.e. advection, diffusion, connected networks, interactions between the main flow and areas of stagnant water or groundwater, etc. Once its numerical performance had been proved, the model was tested in schematic cases and its results compared with analytical solutions. In each case the model showed its ability to represent the natural phenomena very well.