We are interested in simulating overland flow on agricultural fields during rain-fall events. The model considered is the shallow water system (or Saint-Venant equations) without infiltration, complemented with a friction term. In this context, we definitely have to cope with dry/wet interfaces and water inflow on dry soil. We present a simplified one-dimensional model, discretized with a well-balanced finite volume method, and we describe the specific additional features needed to deal with dry/wet transitions and steady-state solutions due to topography and friction. The method as well as the choice of the friction term are tested and discussed both on analytical solutions and experimental results.