Comparing the Morphological Behaviour of Dutch–Danish Shoreface Nourishments

In the Netherlands and Denmark, gradual structural coastal erosion is occurring due to sea level rise, natural redistribution of sand and human intervention. On longer time scales, this gradual erosion increases the risk of coastal flooding, threatens buildings on the dune, fresh water extraction, dune habitats and beach recreation.

Both countries have a coastal erosion policy aiming at compensating the sediment losses by means of sand nourishments. The nourished sand is being placed either at the beach (typically between +3 and -1 m MSL) or in deeper water on the shoreface (at depth around -4 to -5 m MSL). The effectiveness of beach nourishments in relation to coastal erosion is quite well known. However the effectiveness and morphological behaviour of shoreface nourishments is not fully understood (Spanhoff and van de Graaff, 2006). A better understanding of effective shoreface nourishment techniques/placement/management is necessary in order to be able to maintain our eroding sandy coastlines in an efficient way.