A. Nnafie1*, H.E. de Swart1, A. Falqués2, T. Verwaest3
1 Institute for Marine and Atmospheric research Utrecht (IMAU), Utrecht University; 2 Universitat Politècnica de Catalunya (UPC), Barcelona, Spain; 3 Flanders Hydraulics Research, Antwerp, Belgium
A substantial portion of the world's shorelines are being threatened by erosion, a situation that might accelerate by rising sea levels and changes in storm and wave climate. In order to mitigate risks of shoreline erosion, it is crucial to increase our knowledge of the processes that affect shoreline evolution on yearly and decadal time scales. Many studies [1,2] have focused on the evolution of shorelines on decadal time scales, but little is known about the role of tides in this evolution. As tides affect sediment transport in the nearshore, they might significantly impact the evolution of shorelines in macro-tidal coastal environments, such as the Belgium coast (Fig. 1a). This study, which is part of a new research project of the Flemish government (called MOZES), aims to quantify the relative effects of tides on the decadal evolution of shorelines.
Simulations are carried out with an existing idealized 2DH shoreline evolution model (called Q2D-morfo, ), but extended such that tides are included. The macro-tidal Belgium coastal zone (Fig. 1a) is selected as a study area, which features the presence of large-scale ridges on the shelf. The model is forced with waves and tides. Different scenarios of tidal amplitudes are explored.
Results indicate that the inclusion of tides suppresses the growth of shoreline undulations (Fig.1b). Results for different tidal scenarios will be presented during the conference.
Figure 1: a) Bathymetric map of the Belgian shelf, which shows a field of the so-called shoreface-connected sand ridges (sfcr) and tidal sand ridges (tsr). b) Rms amplitude of shoreline undulations (with respect to the initially straight shoreline profile) versus time.
 Montaño, et al. (2020). Blind testing of shoreline evolution models. Sci Rep 10, 2137. https://doi.org/10.1038/s41598-020-59018-y.
 Mutagi et al. (2022). Shoreline Change Model: A Review. Sustainability Trends and Challenges in Civil Engineering. Lecture Notes in Civil Engineering, vol 162. Springer, Singapore. https://doi.org/10.1007/978-981-16-2826-9_64.
 Safak et al. (2017). Persistent shoreline shape induced from offshore geologic framework: Effects of shoreface connected ridges. Journal of Geophysical Research: Oceans, 122(11), 8721–8738. https://doi.org/10.1002/2017JC012808.