A two-dimensional model for the analysis of sloshing phenomena in shallow-water conditions has been defined using Boussinesq-type depth-averaged equations. Thanks to a modal decomposition of the spatial field, the present model allows a straightforward and simple treatment of the exciting forces and can describe a generic motion. Comparisons with the experimental data available in the literature and with a smoothed particle hydrodynamics (SPH) scheme proved the proposed shallow-water model to be accurate, fast and robust.