The meteorological model RAMS and the Lagrangian particle model SPRAY are coupled to simulate the transport and diffusion of tracer released during the project TRACT, realized in the Rhine valley, Central Europe. The simulation results generated by the model system are evaluated against observational data measured in the TRACT experiments. Analysis of the results and the application of statistical indices show that the considered models reproduce well the general behaviour of the contaminant plume, the temporal and spatial distribution of the concentration and the location of the concentration maxima.