Large parts of The Netherlands are protected from flooding by a narrow strip of sandy beaches and dunes. The aim of this thesis is to extend the existing knowledge of dune erosion during storm surges as it occurs along the Dutch coast. The thesis discusses: • A large scale dune erosion experiment to obtain better insight in near dune hydrodynamics, sediment transport and the interaction between dune face and swash zone; • Detailed models to study dune erosion physics, which are validated against measurements; • A morphodynamic dune erosion model that includes the longshore direction and new physical insights. The model is applied in a variety of dune erosion conditions.