On the redistribution and sorting of sand at nourishments: Field evidence and modelling of transport processes and bed composition change

Increasingly large sand nourishments are used for the maintenance of sandy coasts around the world. There is, however, still very limited understanding of their behaviour (i.e. redistribution) and effects on the marine environment. This PhD thesis explores the morphological reshaping of shoreface nourishments (i.e. long bunds of sand placed at...

Observations and modelling of shoreface nourishment behaviour

Shoreface nourishments are commonly applied for coastal maintenance, but their behaviour is not well understood. Bathymetric data of 19 shoreface nourishments located at alongshore uniform sections of the Dutch coast were therefore analyzed and used to validate an efficient method for predicting the erosion of shoreface nourishments. Data shows...

Behaviour of subtidal sandbars in response to nourishments

The behaviour of subtidal sandbars can be strongly influenced by the introduction of sand nourishments in the coastal system. This study focuses on the impact of nourishments on subtidal bar behaviour at spatio-temporal scales beyond a single nourishment project. It aims to determine the long-term behaviour of subtidal sandbars along an entire...

Modelling of bed sediment composition changes at the lower shoreface of the Sand Motor

Large perturbations in the coastline, such as the 'Sand Motor' nourishment (∼21 million m³) at the Holland coast, can initiate considerable spatial and temporal changes in the median grain size (D₅₀) of the sea bed on the lower shoreface. The relevance of hydrodynamic conditions for the development of the heterogeneity...

Numerical modelling of erosion rates, life span and maintenance volumes of mega nourishments

Mega-nourishments, aiming at providing long-term coastal safety, nature qualities and recreational space, have been applied recently at the Holland coast and are considered at various other places in the world. Methods to quickly evaluate the potential and lifetime of these coastal mega nourishments are therefore very much desired, which is...

Evolution of alongshore bathymetric variability around a mega-scale beach nourishment

The presence of complex nearshore sand bar patterns (i.e. alongshore bathymetric variability) has an impact on local currents, affecting recreational safety and nearshore mixing processes. This study assesses the evolution of alongshore bathymetric variability along the Delfland coast in The Netherlands, over the first 5 years after construction...

Sediment sorting at the Sand Motor at storm and annual time scales

Bed sediment composition, with a focus on the median grain size D₅₀, was investigated at a large-scale nourishment (The ‘Sand Motor’) at the Dutch coast (∼21.5 million m³ sand). Considerable alongshore heterogeneity of the bed composition (D₅₀) was observed as the Sand Motor evolved over time with (1)...

Advection and diffusion of shore-attached sand nourishments

Understanding of the behaviour of coastline perturbations at soft-coastlines is essential for modelling coastal evolution at decadal time scales. Many coastline models do, for example, implicitly assume dominant diffusive behaviour of coastline features. The validity of this assumption is investigated for the Dutch coast on the basis of data on...