Dune growth on natural and nourished beaches : ‘ A new perspective ’

This thesis describes dune development on natural and nourished beaches on an engineering timescale. Using a study of both literature and data gathered from the Dutch coast, a new hypothesis regarding the causes of variability in dune evolution is proposed. Following this hypothesis assumptions are made on the basis of which a conceptual model is developed that includes both the accretive and erosive processes that govern dune evolution. I would like to thank my supervising committee for guiding me through the process of writing this thesis. Special thanks are due to Stefan for offering me the opportunity to do this work for Boskalis, to Mark for guarding the process, and to Sierd for being a great sparring partner during the writing process. Thanks are rendered to Bert, for his geological know-how and for helping me find literature. More special thanks are due to Mark, Gerben and Kees for sharing their MATLAB knowledge, and especially for the effort they put in the development of the UCIT, McTools and OpenEarth projects; without these projects it would not have been possible to access, process and study the vast amounts of data that have been gathered from the Dutch coast. Finally, I would like to thank my family for their support, my (ex-)housemates for the wonderful years at the OIP, and my fellow students at Deltares for all the lunches and lunch walks: Summary 5 Summary To be prepared for the expected changes in our climate, the Delta Committee recommends to significantly strengthen the dunes along the Holland coast. It is possible to nourish the dunes directly, but this is an expensive and intrusive operation. Foreshore nourishments are cheaper, and less intrusive to both the natural and human environment. It is expected that large-scale foreshore nourishments can also positively affect dune development. As the Zuid-Holland coast must be extensively nourished anyway, the idea has risen to do a single, concentrated (in time and space) nourishment, instead of repeating many smaller ones. This will reduce both the costs and the impact. Also, this large nourishment is expected to locally stimulate dune development. As a pilot project a 20 million m 3 nourishment is currently being prepared, named " the sand engine ". As potential dune development is one of the design criteria, it is desired to know in advance what influence on dune development can be expected from such a nourishment. As current understanding of …