RIPOST: A River Pollution Simulation Tool To Anticipate The Consequence Of Accidental Spills

Accidental pollutant spills are frequent and their impact on water uses downstream difficult to assess precisely in the framework of a crisis management. Therefore, a specific tool, named RIPOST, dedicated to drinking water treatment plant operators was developed to anticipate the consequence of a spill upstream the plant intake. As a decision support tool, RIPOST had to fulfil operational needs: ease of use for operators, quick calculation and providing key information for decision making. A new numerical pollutant spill and transport model has been developed by using integrated Eulerian method under the Telemac 2D software instead of the 1D model usually used. This model enables to simulate the main processes that act on the spilled pollution; in particular it can calculate the transfer time and the transverse concentration gradient evolution along the river whereas 1D model provide also the transfer time but only the mean concentration. That permits to have more relevant results on the transfer time of the pollution, on its maximal concentration, and on alert information based on thresholds at the water intake. In order to be used by non-modellers, the numerical pollutant spill simulation is controlled using a friendly Graphical User Interface (GUI). Using only few parameters (location, duration, volume, concentration of the pollution), and thanks to a simulation time compatible with crisis management, the tool will provide transfer time and pollutant concentration so that the stakeholder can make its decision. The GUI also allows easy integration of new river models by modellers, by facilitating, for example, the definition of points of interest (like dam, or water intake) and also the calculation of the river curvilinear abscissa (called PK: mileage points). In order to validate the simulation system and the GUI, some tracer experiments in real condition were simulated for five rivers in France