The commonly used approach for modelling unsteady river morphological processes considers Saint Venant-Exner equations, with local equilibrium condition for the solid discharge evaluation. Despite its widespread application, some physical behaviors related to sediment dynamics are not represented by the above model. Recently, some different morphodynamical models have been proposed, in order to overcome these limitations. In this paper a two-phase morphodynamical model is presented. The model eigentructure is analysed and its hyperbolic nature is shown. Simulations of laboratory documented test-cases are finally carried out, enlightening the potentialities of the proposed model.