INITIAL SAND LOSSES AND LIFE SPAN PREDICTIONS FOR MEGA-NOURISHMENTS ALONG THE DUTCH COAST

In the summer of 2011 about 19 million m3 of sand was dumped near Ter Heijde, The Netherlands to protect the rather small beach-dune system at this location. On the long term this mega-nourishment will be gradually smoothed out along the coast, feeding the adjacent beaches and dunes. The initial sediment losses over the first years of this mega-nourishment have been modelled successfully using both 1D and 2DH coastal models. Based on a series of computations for mega-nourishments with various length-to-width ratios and volumes, design graphs for erosion rate and life span of mega-nourishments have been derived. These design graphs have been applied to estimate erosion volumes and maintenance volumes for mega-nourishments near Katwijk and Noordwijk, The Netherlands.