Seaward coastal defence: limitations and possibilities

In The Netherlands shoreline retreat is actively counteracted, mostly by means of beach nourishment in which some allowance is made for natural fluctuations. For some parts of the coast, however, a more active socalled ‘seaward coastal defence strategy’ might be more profitable. This applies to coasts with a small dune ridge subject to severe erosion. According to this strategy the morphological system is influenced in such a way that erosion is prevented, which will result in a stable or even an accretion coastline. The effectiveness of the seaward coastal defence strategy has to be compared with maintenance by beach nourishment. The effects on the morphological system, the environment and other interests must also be analysed. Several seaward solutions are possible. In order to gain more insight into the behaviour of these solutions, comparative pilot studies have been executed for the most vulnerable locations. This paper gives an overview of the main conclusions of the pilot studies in comparison with sand nourishment, the main coastal defence measure.