2d Overtopping and Impact Experiments in Shallow Foreshore Conditions

Gruwez, Vincent; Vandebeek, Ine; Kisacik, Dogan; Streicher, Maximilian; Altomare, Corrado; Suzuki, Tomohiro; Verwaest, T.; Kortenhaus, Andreas; Troch, Peter

doi:10.9753/icce.v36.papers.67

Cited by 3 publications

(3 citation statements)

References 9 publications

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“…The average and maximum depths are 20 m and 45 m, respectively. In the cross-shore direction the seabed is mildly sloping, ranging between 1:20 and 1:90 [31]. However, the bathymetry is also marked by a complex system of large and elongated submerged sandbanks, the Flemish Banks.…”

Section: Dynamics Of the North Seamentioning

confidence: 99%

ROMS Based Hydrodynamic Modelling Focusing on the Belgian Part of the Southern North Sea

Klonaris

Eeden

Verbeurgt

et al. 2021

JMSE

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The North Sea is a shallow sea that forms a complex physical system. The nonlinear interaction of the astronomical tides, varying wind fields and varying pressure systems requires appropriate approaches to be described accurately. An application based on the advanced numerical model Regional Ocean Modeling System (ROMS) was newly developed by the authors, tailored to simulate these hydrodynamic processes in the North Sea and the Belgian Continental Shelf, which is the area of particular interest in the present study. The purpose of this work is to develop and validate a state-of-the-art three-dimensional numerical model to form the basis of a compound operational and forecasting tool for the Belgian coastal zone. The model was validated with respect to water levels and temperature. Validation for astronomical tides was accomplished through the comparison of the principal constituents between the model results and observations at a number of tidal gauges in Belgium and other countries. A statistical analysis of the results showed that the model behaves as expected throughout the North Sea. The model response to the varying meteorological conditions was also validated using hindcast data for 2011 as input. In this case, the comparison between observed and modelled water levels showed a good agreement with average RMSE in Belgium 9.5 cm. Overall, the added value of this work is the development of an independent model for validation and comparison with other models and which can be used as an efficient tool for operational and forecasting purposes.

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Section: Dynamics Of the North Seamentioning

confidence: 99%

ROMS Based Hydrodynamic Modelling Focusing on the Belgian Part of the Southern North Sea

Klonaris

Eeden

Verbeurgt

et al. 2021

JMSE

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“…This paper presents the field setup for observations of IG waves offshore and nearshore at Living Lab Raversijde (LLR) with the Research Dike Raversijde (RDR) (presented by Gruwez et al (2024), also at Coastlab24) measuring the wavestructure interactions (overtopping, impact,…), and presents the results of IG wave influence on wave overtopping, including free IG waves. Finally, a first evaluation of existing empirical formulas with the field measurements is done.…”

Section: Introductionmentioning

confidence: 99%

Field Observations Of The Influence Of Infragravity Waves On Wave Overtopping At A Dike On A Shallow Foreshore

GRUWEZ,

BOONE,

SUZUKI

et al. 2024

CoastLab

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Infragravity (IG) waves are low-frequency waves (0.0033 Hz < f < 0.05 Hz) that exist: (i) being bound to the wave groups of high-frequency sea-swell (SS) waves (0.05 Hz < f < 1 Hz), (ii) generated by the moving breakpoint due to the groupiness of the SS waves (Bertin et al., 2018), and (iii) as free IG waves released from the SS wave groups and reflected from neighbouring coasts (Rijnsdorp et al., 2021). Offshore in deeper water (h/Hm0,o > 4, with h the water depth and Hm0,o the offshore significant wave height), IG waves become most apparent during storm conditions, but are still rather limited in wave height (order of a couple of cm). However, at the toe of coastal structures with a shallow foreshore depth (1 < ht/Hm0,o < 4, with ht the water depth at the toe), the energy of IG waves becomes more significant relative to the SS wave frequency band of the wave spectrum (Hofland et al., 2017), becomes equally important for very shallow foreshores (0.3 < ht/Hm0,o < 1), and even dominates SS wave energy for extremely shallow foreshore depths (ht/Hm0,o < 0.3). IG wave growth on mildly sloped shallow foreshores is a result of IG wave shoaling and SS wave energy transfer to IG waves via nonlinear wave-wave interactions (Bertin et al., 2018), and the relative growth of IG to SS wave energy is further aided by SS wave breaking. Coastal urban areas along the Belgian coast (and in other low-lying countries worldwide) rely on a hybrid beach-dike coastal defense system for protection against flooding. During design storm conditions, the nourished beach erodes to a very to extremely shallow foreshore in front of a low-crested impermeable sea dike. Wave overtopping at this type of structure has been shown to be affected by IG waves, based on physical (Altomare et al., 2016) and numerical modelling (Lashley et al., 2021) for shallow to extremely shallow foreshores. However, field observations of the influence of IG waves on wave overtopping have been scarce (van Gent and Giarusso, 2003) and the influence of free IG waves has not been investigated yet. Indeed, the amount of IG wave energy that is expected to arrive at the coastline, not only depends on IG waves naturally bound to the SS wave groups, but also on free IG waves generated offshore or locally reflected from the coast (edge waves). The Belgian continental shelf is characterized by the prevalence of offshore sandbanks (see Figure 1a), which might be an additional source of free IG waves, due to ss wave breaking on the shallow crest of those banks. These free IG waves are location specific and their existence can only be determined by field observations. Knowledge of the offshore boundary conditions with detailed IG wave information is indispensable for the correct prediction and modelling of surf zone hydrodynamics and beach morphodynamics (Fiedler et al., 2019), and the consequent wave overtopping on the dike. Simultaneous measurements of IG waves, offshore and on the beach-dike system during storm conditions together with wave overtopping has not been done before, as it is complex and needs a specific setup with high precision measurement equipment. In-situ measurements provide an invaluable dataset (i.e., no model nor scale effects) and are essential for validating safety assessment and design methodologies of coastal defense systems.

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“…Therefore, typically experimental modelling is done for this specific case [2]. However, numerical modelling has become a possibility as well by applying computational fluid dynamics (CFD) techniques.…”

Section: Introductionmentioning

confidence: 99%

An Inter-Model Comparison for Wave Interactions with Sea Dikes on Shallow Foreshores

Gruwez

Altomare

Suzuki

et al. 2020

JMSE

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Three open source wave models are applied in 2DV to reproduce a large-scale wave flume experiment of bichromatic wave transformations over a steep-sloped dike with a mildly-sloped and very shallow foreshore: (i) the Reynolds-averaged Navier–Stokes equations solver interFoam of OpenFOAM® (OF), (ii) the weakly compressible smoothed particle hydrodynamics model DualSPHysics (DSPH) and (iii) the non-hydrostatic nonlinear shallow water equations model SWASH. An inter-model comparison is performed to determine the (standalone) applicability of the three models for this specific case, which requires the simulation of many processes simultaneously, including wave transformations over the foreshore and wave-structure interactions with the dike, promenade and vertical wall. A qualitative comparison is done based on the time series of the measured quantities along the wave flume, and snapshots of bore interactions on the promenade and impacts on the vertical wall. In addition, model performance and pattern statistics are employed to quantify the model differences. The results show that overall, OF provides the highest model skill, but has the highest computational cost. DSPH is shown to have a reduced model performance, but still comparable to OF and for a lower computational cost. Even though SWASH is a much more simplified model than both OF and DSPH, it is shown to provide very similar results: SWASH exhibits an equal capability to estimate the maximum quasi-static horizontal impact force with the highest computational efficiency, but does have an important model performance decrease compared to OF and DSPH for the force impulse.

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2d Overtopping and Impact Experiments in Shallow Foreshore Conditions

Cited by 3 publications

References 9 publications

ROMS Based Hydrodynamic Modelling Focusing on the Belgian Part of the Southern North Sea

ROMS Based Hydrodynamic Modelling Focusing on the Belgian Part of the Southern North Sea

Field Observations Of The Influence Of Infragravity Waves On Wave Overtopping At A Dike On A Shallow Foreshore

An Inter-Model Comparison for Wave Interactions with Sea Dikes on Shallow Foreshores

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