The state of the art in most urban dispersion models is to use turbulence and surface exchanges parameterizations, which are designed for non-urban terrain. In this thesis, we use the urban module of Martilli. This scheme computes the impact of three urban surface types (Roof, Road, Wall) on the momentum, heat, and turbulent kinetic energy equation. It also considers the shadowing and radiation trapping effect. In the first part, a new version of the urban module of Martilli has been developed in which improvements are made in 3 ways: ( ) introduction of the vegetation effect, ( )...