We are interested in simulating overland flow on agricultural fields during rainfall events. In this context, we definitely have to cope with dry/wet interfaces and water inflow on dry soil. The model considered is the Shallow Water system (or Saint-Venant equations) without infiltration. Moreover, the model has to be completed with friction terms. It is numerically solved by a finite volume method. The topography and friction terms are treated by a well-balanced strategy with specific additional features to deal with dry/wet transitions. The method as well as the choice of the friction term are validated on both analytical solutions and experimental dataset produced by INRA-Orl´eans.