Short term morphological wave impact on the Zandmotor; a conceptual model

The Zandmotor is world’s first project on mega nourishments at the Delfland coast, the Netherlands. This hook shape nourishment consists of 18,5 million m3 of sand and has been implemented in July 2011 at one location. During the design most researches on the morphological behavior of the Zandmotor was focused on the long term development, based on model calculations with an average wave climate for the next 20 years. However, aerial photos up to January 2012 show significant morphological changes within months due to a more extreme wave climate. The focus of this research is to understand the short term (i.e. monthly) morphological behavior of the Zandmotor due to the wave climate of July 2011 to January 2012. Hindcasts have been performed with the morphodynamic Delft3D model with updated bathymetries based on monthly measurements. Based on these hindcasts, bathymetric measurements and aerial photos, the hydrodynamic and morphodynamic processes around the Zandmotor have been analyzed. This analysis has resulted in a conceptual model, which presents the morphological change of the Zandmotor due to waves from different directions. With this model, the morphological development over the period July 2011 to January 2012 may be explained.