Two-dimensional river pollution model with particle simulation

A horizontally 2D transport model is described. The model is based upon the computation of particle displacements. The longitudinal displacements are derived from the transverse velocity profile. Transverse exchange is simulated by rand displacements. Common geometric and hydraulic characteristics of the river and discharge of the river and its tributaries are supposed to be given. For the river Rhine, for example, fair estimates of velocity profiles and transverse exchange coefficients can be derived from existing data and from the literature on mixing in rivers. The accuracy of the results will gradually increase by adjustments on the basis of fields data such as obtained from natural and artificial tracers. The use of discrete particles as a technique to solve the diffusion- advection equation simplifies the programme and prevents numerical problems. Because of the very short computing times, the model can also be used as a calamity model.