Sand nourishments are defined as the artificial supply of sand near or on the beach to counteract coastal erosion. They are considered a successful adaptation strategy, and they have become more large-scale over time especially in the Netherlands. Furthermore, the ecological ranking classification—introduced by van der Nat et al. (2016)— classifies them as soft solutions, which are preferred to hard structures. The 2024-2030 Sand nOURishment strategies for sustainable Coastal Ecosystems (SOURCE) research project focuses on understanding, utilizing, and protecting coasts through the implementation of nourishments, see . www.source-research.nl.
One type of nourishment is shoreface nourishment; this nourishment is usually placed against the outer breaker bar, or in the trough of the natural bar system in the breaker zone (see Figure‑1). Sand used in shoreface nourishments is neither uniform in size nor has the same size distribution as its surrounding environment. However, how grain sizes influence cross-shore transport rates and directions of size fractions is not clear. How bed levels, sorting processes and bed compositions in the cross-shore profile are related is not well understood.
Figure‑1 Shoreface nourishment located at the outer breaker bar
Six shoreface nourishment cases with different grain sizes will be tested in the laboratory flume of the Technical University of Denmark (DTU) in Copenhagen. Three sand mixtures will be used to nourish the shoreface in these experiments: a fine uniform sand, a coarse uniform sand, and a mixture of them (fine and coarse). Moreover, the effect of placement of the nourishment on the bar and the trough will be investigated (see Figure‑2). All experiments will be exposed to the same wave conditions and a wide range of hydro- and morphodynamic data will be collected.
Figure‑2 Schematic representation of the flume at DTU with a nourished bar adapted from Larsen et al. (2022)
Firstly, bed levels will be compared between the experiments to reveal grain size effects on the morphology. Secondly, temporal and spatial changes in sediment size composition and transport rates within each of the experiments will be analyzed. The objective of this project is to observe, understand, and quantify grain size effects on the shoreface nourishment morphodynamics, and to identify underlying transport and sorting processes. The expectations from the prospective candidate are as follows:
- Assisting in conducting experiments at the DTU laboratory in Copenhagen for 2-3 months (this might be extended one month using a capita selecta)
- Processing and analyzing part of the extracted experimental data
We are seeking a student who is enthusiastic about performing experiments, analyzing data, and interpreting the results. The student will directly collaborate with a PhD student and will gain great laboratory experience in Denmark.
Ideally, the project duration will be extended with 3-4 weeks through a capita selecta of 5 EC. There is budget available to cover (part of) the travel and subsistence costs.
References
- Biegel, E. J. (1994, November). Morphological development of a shoreface nourishment, Terschelling, The Netherlands (NOURTEC project report). RWS.
- Brand, E., Ramaekers, G., & Lodder, Q. (2022). Dutch experience with sand nourishments for dynamic coastline conservation – An operational overview. Ocean and Coastal Management, 217. https://doi.org/10.1016/j.ocecoaman.2021.106008
- Guillén, J., & Hoekstra, P. (1996). The “equilibrium” distribution of grain size fractions and its implications for cross-shore sediment transport: a conceptual model. In Marine Geology (Vol. 135).
- Guillén, J., & Hoekstra, P. (1997). Sediment Distribution in the Nearshore Zone: Grain Size Evolution in Response to Shoreface Nourishment (Island of Terschelling, The Netherlands). In Estuarine, Coastal and Shelf Science (Vol. 45).
- Huisman, B. J. A., de Schipper, M. A., & Ruessink, B. G. (2016). Sediment sorting at the Sand Motor at storm and annual time scales. Marine Geology, 381, 209–226. https://doi.org/10.1016/j.margeo.2016.09.005
- Huisman, B. J. A., Walstra, D. J. R., Radermacher, M., de Schipper, M. A., & Ruessink, B. G. (2019). Observations and modelling of shoreface nourishment behaviour. Journal of Marine Science and Engineering, 7(3). https://doi.org/10.3390/jmse7030059
- Larsen, B. E., Van Der A B, D. A., Carstensen, R., Carstensen, S., & Fuhrman, D. R. (2022). Experimental investigation on the effects of shoreface nourishment placement and timing on long-term cross-shore profile development. https://doi.org/10.11583/DTU.16739449
- Medina, R., Losada, M. A., Losada, I. J., & Vidal, C. (1994). MARINE GEOLOGY Temporal and spatial relationship between sediment grain size and beach profile. In Marine Geology (Vol. 118). ELSEVIER.
- van der Nat, A., Vellinga, P., Leemans, R., & van Slobbe, E. (2016). Ranking coastal flood protection designs from engineered to nature-based. Ecological Engineering, 87, 80–90. https://doi.org/10.1016/J.ECOLENG.2015.11.007
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