Numerical simulation has become an important research area thanks to the development of (super)computers. It has been applied to many areas such as medicine, aerodynamics, manufacturing, natural hazards, etc. Namely, its application to environmental systems has been widely studied. In this framework, the shallow water hypothesis is a powerful tool in order to develop mathematical models. Under this assumption the vertical variations of the fluid are neglected. Recently, multilayer models appeared as a solution to this lack of vertical structure. In this talk, our objective is to briefly present these kind of models. We will also show some of its applications to different geophysical problems as granular flows and polydisperse sedimentation.