A depth-averaged two dimensional model TIFS was developed from simplified basic flow equations. The model was applied to tidal computations for the Biin Bay area near the Gunsan port. Vertical tides and tidal velocities for the tested was simulated for neap and spring tides. The simulation results were in good agreement with the obserbed data. This paper also attempts to evaluate model sensitivity from different initial conditions, roughness coefficient, time increments, and water depths. Among the selected input parameters, water depth and roughness coefficient were found to significantly affect vertical and horizontal tides.