Short description and objective of the project:
The lower shoreface forms the transition between the nearshore zone and the offshore seabed and plays a key role in sediment exchange between these areas. Understanding the governing sediment dynamics in this region is therefore essential for predicting coastal evolution and supporting sustainable coastal management. The Dutch lower shoreface is a sandy environment lying between approximately -8 m NAP and -20 m NAP contours. Previous studies have shown that annual sediment transport rates here are sensitive to grain size (Grasmeijer et al., 2022). In addition, field observations along the Noordwijk shoreface show distinct spatial differences in sediment characteristics, with moderately to poorly sorted sands in the nearshore zone and coarser, well-sorted sands offshore (van der Spek et al., 2022). These patterns are thought to result from the supply of river-sourced deposits and their selective transport and sorting further offshore. However, the processes governing the redistribution of sediment across the lower shoreface, and the role of grain-size-dependent transport in shaping these patterns, remain unclear.
Fig. 1: Overview of the Dutch coastal zone (van der Spek et al., 2022).
In this study, the student will investigate how spatial variations in sediment grain size influence sediment transport rates and the resulting redistribution along the lower shoreface near Noordwijk. A Delft3D model will be used to simulate hydrodynamics and size-dependent sediment transport. A calibrated hydrodynamic model is available, and the focus will be on implementing and analysing multi-fraction sediment transport. Model results will be evaluated against sediment observations from Coastal Genesis 2.0. The project will provide new insights into the role of grain-size-dependent transport in shaping sediment distribution on the Dutch lower shoreface, contributing to improved process understanding and model representation of lower shoreface sediment dynamics.
References (optional):
Grasmeijer, B., Huisman, B., Luijendijk, A., Schrijvershof, R., Van Der Werf, J., Zijl, F., ... & De Vries, W. (2022). Modelling of annual sand transports at the Dutch lower shoreface. Ocean & Coastal Management, 217, 105984. https://doi.org/10.1016/j.ocecoaman.2021.105984
van der Spek, A., van der Werf, J., Oost, A., Vermaas, T., Grasmeijer, B., & Schrijvershof, R. (2022).
The lower shoreface of the Dutch coast–An overview. Ocean & Coastal Management, 230, 106367. https://doi.org/10.1016/j.ocecoaman.2022.106367
