It has been reported that tsunamis, which have arrived at river mouths, sometimes run up in rivers and that the wave flows cause serious damage in structures. In order to evaluate the related local phenomena, such as the transportation of floating materials, fluid forces caused by wave flows and flows over river banks, a 3D computational method, MICS (Multiphase Incompressible flow solver with Collocated grid System) is thought to be effective, since it enables us to deal with the front of free surface flows and evaluate fluid forces without empirical formulations. Some basic hydraulic experiments were carried out and the measured wave flows and their flooded flows were compared with the predictions.