The Object of this paper is to advance the reproduction of simulation results by improving the ordinary boundary conditions. It is to be introduced the moving boundary at the closed boundary and the non-reflective boundary at open boundary in numerical model. The simulation target is the North Bay in Ariake Sea. The reproduction in the present state on tidal currents in this bay had been examined by applying the simulation program based on the numerical model. The effects were considered in case of adding each moving boundary and non-reflective boundary condition, and then considered in case of combing these boundary conditions simultaneously. The reproduction on the tidal currents by this simulation was improved, especially by the simulation combined with the moving and non-reflective boundary conditions.
