Motion of Water and Sediment under Standing Waves in the Swash Zone

A long wave run-up model is applied to calculations of wave-induced flow velocities, sediment transport rates and bottom changes in a swash zone. First, properties of the water tongue motion and resulting lithodynamic response are analysed theoretically. Next, an attempt is made to run the model for the natural conditions encountered on the south Baltic Sea coast. The Lagrangian wave-induced velocities are used to determine the Eulerian phase-resolved bed shear stresses with a momentum integral method, after which the motion of sand is described by use of a two-layer model, comprising bedload and nearbed suspended load. Seabed evolution is then found from spatial variability of the net sediment transport rates.