Analysis of Dune Erosion on the Coast of South Baltic Sea Taking into Account Dune Landslide Processes

Abstract An analysis was carried out to determine the influence of landslide process at a few meters depth under the dune surface on the rebuilding of the dune. In the first step, calculations were done using the XBEACH model to determine seabed rebuilding as well as shore and dune undercutting for the assumed hydrologic and hydrodynamic conditions. Next, the obtained tachymetric profile of the dune and beach was fed into the FLAC2D program, and calculations of stress distribution, displacements and stability conditions were made. In this way, landslide movement was identified. The theoretical investigations clearly prove that waves attacking the dune not only cause surface erosion, but also trigger a landslide within the dune mass to a maximum depth of about 5 m. It results in a lowering of the dune crown by about 0:6 ÷ 0:7 m. Numerical models such as XBEACH, SBEACH or CSHORE do not take into account landslide occurrence, and thus underestimate dune erosion.