Increasing pressures on coastal environments induced by sea level rise and coastal squeeze has meant that tracking the morphological evolution of sedimentary coasts from the last known survey, pre-empting storm impacts and forecasting potential beach recovery following extreme events is of substantial and increasing societal importance. Equilibrium models for forecasting coastal evolution have figured

The interactions of random waves with a cluster of structures positioned in a gridded array are investigated through a series of experiments and high-fidelity RANS and LES simulations. The performances of two different turbulence models, k−ω SST and LES, are evaluated in terms of the predicted flow field and resulting loading on the structures, both in the time and frequency domains. The comparative

Long-term coastal management of beach/dune systems requires the definition and assessment of storm events. This study presents a framework using statistical analyses and numerical modelling (XBeach) to characterize storm events and investigate their impact on beach/dune erosion. The method is developed using exemplary data from Formby Point on the Sefton coast (UK), which has a complex beach morphology

Single-layer cube (SLC) armoured breakwaters with a regular placement pattern are a relatively recent concept despite the cube being one of the oldest concrete units available. Limited investigation on the performance and hydraulic stability of this armour type is available to date. This work presents a quantitative assessment of the damage evolution for SLC armoured breakwaters with a regular placement

The design load from waves on offshore structures are often estimated by aid of experimental studies in wave flumes and basins. When going from open sea to laboratorial conditions a number of factors are either added or omitted such as wind above waves. The paddle-generated waves are based on a spectrum taking the indirect effect of wind into account, whereas the direct effect of wind is left out.

The measurement of wave forces acting on marine structures is a complicated task, both during physical experiments and, even more so, in the field. Force transducers adopted in laboratory experiments require a minimum level of structural movement, thus violating the main assumption of fully rigid structure and introducing a dynamic response of the system. Sometimes the induced vibrations are so intense

Mapping bathymetric change is a core task for a wide range of navigation, research, monitoring, and design applications. Satellite-derived bathymetry (SDB) can support this activity, particularly when using data from a platform, like the Sentinel-2A/B twin mission of the Copernicus programme, which provides routine and repetitive image acquisition at 10 m spatial resolution. As a result, SDB can expand

The performances of phase-averaged parametric nearshore wave transformation models depend significantly on a reliable estimate of the wave breaker index γ (the breaker height-to-depth ratio), a free model parameter that essentially controls the amount of breaking energy dissipation. While the previous studies have suggested separate relationships between γ and the offshore wave steepness (s0) or the

This study aims at improving the XBeach model in predicting dune erosion in the presence of belowground (land-based) biomass under varying hydrodynamic conditions. In this regard, the XBeach model was extended by a literature-derived root model, which increases the critical velocity for erosion in user-defined areas due to additional root cohesion. The model was validated by using the results of a

Destruction of the structures in coastal areas due to an extreme coastal event like a tsunami necessitates the deeper understanding of flow behaviour to improve the design guidelines. The characteristics of inland propagating tsunami surge or bore consist of an initial aerated surge or bore tip followed by the gradual increase in water depth (quasi-steady flow phase). During the bore interaction, the

The main objective of this research is to present an improved and more accurate formula to estimate the reflection coefficient (KR) for rubble mound breakwaters. Physical model tests were performed for this purpose and existing data was also considered. The evaluation of existing prediction formulas for KR based on the Iribarren number (ξ) shows that the scatter in the experimental results increases

A new methodology is proposed to estimate storm demand and dune recession by clustered and non-clustered events, to determine if the morphological response to storm clusters results in greater beach erosion than that from individual storms that have the same average recurrence interval (ARI) or return period. The method is tested using a numerical morphodynamic model that combines both cross-shore

The flow field around a vertically mounted circular pile exposed to gradually-varied unsteady flow is experimentally investigated. Experiments were conducted in a 30 m-long and 1 m-wide recirculating flume equipped with a variable discharge pump. A circular cylinder with 9 cm diameter was used as the model pile. To understand the influence of accelerating and decelerating flow conditions, three unsteady

Coastal systems are extremely dynamic environments exposed to many hazards, making accurate and regular monitoring a major challenge, particularly in the context of global change and sea level rise. In this frame of reference, high-frequency, high-resolution coastal Video Monitoring Systems (VMS) have been installed on three megatidal (tidal amplitude > 9 m) sites of Normandy (France) including a sandy

Results are presented from a variational data assimilation and nearshore bathymetry inversion scheme based on depth and wave-phase averaged surfzone hydrodynamics for a narrow-banded wave spectrum. 1-D Cross shore bathymetry is inverted based on 17-min-averaged significant wave height and longshore current observations made during the Duck94 field experiment. An inversion scenario is considered in

In this paper the safety of a double-dike system (or twin dikes) is assessed. Such a system consist of two parallel lines of flood defences. During storms the combined strength of the parallel flood defences must prevent flooding of the hinterland. A culvert can be implemented for the tidal exchange of sea water to enable new land-uses in the area between the dikes such as aquaculture, saline agriculture

An equation of y/x for ship wave crests in a uniform current in the entire range of water depths is developed using the characteristics that the velocity potential is stationary in a ship-moving frame and the ship waves propagate in group velocity, and using the linear dispersion relation. For waves with no current, the developed equation is reduced to the equation of Lee and Lee (2019). Further, in

This Short Communication provides a Coastal Engineering perspective on present and emerging capabilities of satellite optical imagery, including real-world applications that can now be realistically implemented from the desktop. Significantly, at the vast majority of locations worldwide, satellite remote sensing is currently the only source of information to complement much more limited in-situ instrumentation

In deep-water, quasi-resonant four-wave interaction gives rise to the occurrence probability of extreme wave height, which leads to freak wave as a natural disaster. As water wave enters shallow water, four-wave interaction becomes weak and wave shoaling makes this effect become complicated. This study conducts a Monte Carlo simulation in modified Nonlinear Schrödinger equation considering bottom topography

The last IPCC report highlights that, along the present century, sea level rise driven by climate change will exacerbate the flooding frequency in coastal areas. Among the others, the Venice lagoon is one of the most vulnerable because of the presence of worldly famous historical urban settlements. To face this, a mobile flap gate system (Mo.S.E.) is nearly completed and has already raised across the

In the present study, we addressed the potential impact of climate change on coastal erosion along the 28 beaches of the Basque Coast (150 km). A shoreline evolution model including cross-shore and alongshore sediment transport formulations, short- and long-term processes and hard structure treatment is developed. The historical analysis of the shoreline evolution is performed by forcing the model

Although mangroves reduce the daily risk of flood for millions of people, it is still difficult to estimate the protection they provide for variable wave conditions and forest characteristics. This aspect is crucial for the promotion of conservation and restoration of mangrove forests and for the estimation of how the coastal protection service they provide will evolve over time. This paper presents

Wave overtopping is typically measured in the field using overtopping tanks. In this paper, an alternative system is developed that uses two laser scanners. The system also measures wave run-up, as well as run-up depths and velocities, both during perpendicular and oblique waves on a dike in the field. The paper considers the first calibration tests with the system in the field, with perpendicular

The dispersive characteristics of unidirectional irregular waves propagating and breaking over a mildly sloping beach are examined using a highly-resolved laboratory dataset. Cross-spectral analyses are used to determine the cross-shore evolution of (single-valued) dominant wavenumber κ and phase velocity c spectra, and lead to the identification of four different regimes of propagation: I - a linear

Along much of the world's coastline, coastal barriers serve as the first line of defense against oceanic and meteorological forces. Extreme storms cause large morphological changes on coastal barriers through high sediment transport rates, which may degrade their defensive capabilities. The understanding of morphological impacts is therefore important for coastal resiliency, but is often challenged

A non-hydrostatic phase-resolving numerical model (SWASH) is used to investigate the wave-driven nearshore hydrodynamics corresponding to new observations from a three-dimensional physical model in a wave basin. In the physical model, waves from a passing storm are simulated by varying the energy and duration of waves generated by a paddle over time and the beach morphology is surveyed in high spatial-resolution

The influence of a building array on tsunami-driven run-up loads is studied through laboratory experiments and Computational Fluid Dynamics (CFD) simulations. Results show that the number of rows of buildings providing shelter is an explanatory variable for the maximum wave run-up load reduction. Load Reduction Factors (LRF) are defined, with values monotonically decreasing as the number of rows providing

The present paper is the first of two companion papers on the investigations of wave overtopping flow striking a cylinder, which is the schematisation of a human body, on the crest of an impermeable sloped seawall with a deep foreshore. This paper presents the physical modeling part. The key measured physical quantities include the overtopping flow depth on the seawall crest and the inline force on

Stepped revetments limit wave overtopping effectively. Small-scale studies provided insights in the design of crest-levels and step geometries of these structures. The validation of these insights at large scale, along with the analysis of individual overtopping volumes, is required to formulate design recommendations. This paper investigates wave overtopping rates and individual overtopping volumes

Approximately 10% of the world's population lives and works in low-lying coastal regions that are less than 10 m above sea level. This percentage is likely to increase during the remainder of the 21st century due to population growth and economic development. This growth brings the potential for increasing damage and economic losses due to tropical cyclones (hurricanes in North America) accompanied

In many places, sandy coastlines and their associated assets are at high risk of erosion and flooding, with this risk increasing under climate change and sea level rise. In this context, dynamic cobble berm revetments represent a potentially sustainable protection technique to armour sandy beaches, reduce wave runup and protect the hinterland against wave attack. However, the behaviour and performance

Machine learning techniques have inspired reduced-order solutions in the fluid mechanics field that show benefits of unprecedented capability and efficiency. Targeting ocean-wave problems, this work has developed a novel data-driven computational approach, named Wave-GAN. This new tool is based upon the conditional Generative Adversarial Network (GAN) principle, and it provides the ability to predict

Non-stationary Extreme Value Analysis (NEVA) allows to determine the probability of exceedance of extreme sea states taking into account trends in the time series of data at hand. In this work, we analyse the reliability of NEVA of significant wave height (Hs) and peak period (Tp) under the assumption of linear trend for time series of annual maxima (AM) Hs in the Mediterranean Sea. A methodology to

The present paper is the second of two companion papers on the investigations of wave overtopping flow striking a cylinder, which is the schematisation of a human body, on the crest of an impermeable sloped seawall with a deep foreshore. This paper numerically examines the detailed characteristics of the overtopping flow and the force on the cylinder in-line with the flow direction by using a volume-of-fluid

This paper presents a method to include damage at the initial stage of coastal flooding events definition and in return periods computation. The methodology is illustrated within a local study carried out in Biarritz Grande Plage, a meso-tidal, wave dominated beach located on the french basque coast in the south west of France. The work is based on two datasets covering the period 1949–2015: a first

Homogeneous low-crested structures (HLCSs) on hard seabed are designed to protect beaches and regenerate coral reefs. The height of a HLCS depends on the placement grid which determines the crest freeboard, wave transmission and concrete consumption. In real seafloor conditions, it is not easy to define feasible placement grids for HLCSs on uneven sea bottoms. In this study, the parameters of the numerical

Accurate calculation of wave overtopping is important for determining the required crest height and geometry of a dike. Berms and roughness elements are widely used to reduce the average overtopping discharge at dikes while the reductive effects of berm and roughness are still not fully understood. Several empirical formulae are available to predict the overtopping rate at coastal structures. However

A man-made dune-beach-spit system at the south-east side of the island of Texel (Prins Hendrik site) has been built in 2018–2019 to strengthen the traditional dike. The core of the dune-beach-spit system consists of medium fine sand with a d50 of 0.25–0.3 mm. The beach is covered with an armour (protection) layer of coarse materials with relatively large gravel and shell fractions to reduce wind erosion

The statistical properties of ocean wave groups are extremely important for the analysis of resonant effects on ships and marine structures. The patterns in combined sea states have attracted increasing attention recently. This study focuses on the probability distributions of the group height and group length as defined by an envelope approach in sea states with bimodal spectra. Wave data from laboratory

Coastal structures play a major role in protecting people and property given the increasing threat of climate-change-induced flooding. Hence, an accurate prediction of wave overtopping for each structure is required to protect both people and properties on the structure's lee side. In this study, a formula set is developed for predicting the mean wave overtopping rate for vertical and slightly battered

Two successive extreme typhoons, Faxai and Hagibis, hit Eastern Japan and left devastating damage along its long coastline due to high waves. During the two typhoons, the characteristics of extreme waves at Seisho Coast, the most affected coast, were investigated. The investigations were based on wave observation data, post-event surveys, and numerical simulations. The observation data confirmed that

Surface wave breaking induces strong turbulence in the two-phase flow region. Detailed turbulence statistics were experimentally obtained using non-intrusive optical techniques in a breaking bore roller, at relatively large scale, with a bore Froude number Fr1 = 2.15 and Reynolds number Re = 2.3×105. These novel velocity data were ensemble-averaged based upon an instantaneous dataset of 24,320 images

Runup of landslide-generated waves is an important natural hazard in coastal regions, and can result in major damage to the natural and built environment. Past work has investigated the runup of non-breaking waves, whereas, in contrast, little data is available on the runup of waves at the point of breaking prior to interaction with the opposing shore. In the present study, impulse waves were generated

A number of models are available for science and engineering purposes that numerically simulate nearshore hydrodynamics and the corresponding morphological evolution. However, the models include adjustable coefficients in parameterizations for physical processes that need to be calibrated, and thus there remains room for improvement by including additional physics. One such model is XBeach, which can

Model tests with unidirectional random wave fields are common for coastal engineering purposes. In this paper, we investigate the finite water depth effect on both the probability of extreme events and the averaged shape of them in such experimental conditions. We simulate some typical model test conditions with a numerical tool, which solves the fully non-linear wave equations. We find the analytical

Wave overtopping is a critical aspect to take into consideration when designing a coastal structure. An adequate crest geometry (a combination of height and width) is required to maintain the required acceptable safety levels for the population and infrastructure behind the structure. This paper presents the wave overtopping results of laboratory experiments for single-layer cube (SLC) armoured breakwaters

The wave time series that forces phase-resolving models is a source of model uncertainty that can propagate into wave runup predictions when the wave phase information is unknown. The effect of beach morphology on the propagation of this intrinsic uncertainty related to wave randomness (Ui) is largely unexplored. Here, we quantify the importance of uncertainty in wave runup at a dissipative (TS), intermediate

A better understanding of how tidal-flat reclamation changes the flood hazard is critical for climate-proofing coastal flood defense design of heavily urbanized areas. Since the 1950s, large-scale reclamation has been performed along the Shanghai coast, China, to fulfill the land demands of city expansion. We now show that the loss of tidal flats may have resulted in harmful impacts of coastal storm

One of the main challenges facing decision-makers, particularly in highly modified transitional systems (i.e., coastal and inland waters, estuaries, river mouths, deltas, and coastal lagoons), is to determine whether current flood defenses will be sufficient throughout the 21st century. In case they are not, address the questions of where and when flood defenses will fail and how much. The methodology

Water-borne disaster debris can exacerbate the damage on the built-environment through debris impact and debris damming loads and by decreasing the functionality of infrastructure systems after these events. Therefore, an understanding of disaster debris transport is essential for disaster management. In this paper, an experimental study of tsunami-driven debris spreading over a flat testbed was conducted

The subgrid technique provides an efficient way to model coastal hydrodynamics using a relatively coarse grid, but incorporating small-scale geometrical details into the coarse grid model. A typical subgrid model based on the nonlinear shallow water equations applies a certain subgrid algorithm, which is based on either deterministic representation of the mass balance, or stochastically simplified

The paper presents a novel wave boundary model, namely Wavy Interface model, abbreviated as WI, for the particle methods by directly modelling the target wave fronts. In practical engineering problems, the information of the design waves as an input boundary is limited to only the wave heights and periods. To accommodate the situations, the proposed Wavy Interface model is designed to omit a usual

Numerical and physical modeling are the two main tools available for predicting the influence of water waves on coastal or offshore structures. Both models have their strengths and weaknesses. An integrated use of numerical and physical modeling which exploits their advantages can provide an optimal description of full-scale, realistic engineering problems. In this series of two papers, we report on

A new semi-empirical storm surge prediction (SESSP) method is presented that computes tropical cyclone induced storm surge levels as a function of space and time for various storm and geometry input parameters. It distinguishes between five components that contribute to the total surge: the normal, parallel, radial, Ekman, and inverse barometer surge. The parallel surge (caused by shore-parallel gradients

The lattice Boltzmann method (LBM) is a numerical method with high parallel computational efficiency. However, currently few 3D numerical wave model based on LBM can be widely applied to water wave simulations in coastal engineering due to several problems related to numerical instability and numerical accuracy. To develop a high-performance 3D LBM solver for water wave simulations with free surface

This paper provides the experimental validation of the generalized second-order three-dimensional (3D) coupling theory outlined by Yang et al. [Z. Yang, S. Liu, X. Ji, and H.B. Bingham, 2020. A generalized second-order 3D theory for coupling multidirectional nonlinear wave propagation from a numerical model to a physical model. Part I: Derivation, implementation and model verification, submitted for

Maintenance of navigation channels in shelf seas with tidal sand waves usually requires repeated dredging operations. Optimizing these interventions is a difficult task, particularly complicated by the nonlinear morphodynamics of sand wave recovery after dredging. Here we present a process-based model study, incorporating different strategies of dredging in an existing nonlinear sand wave model. We

This paper uses a novel approach to investigate the effect of wave-current interactions on the wave loads on a vertical surface piercing cylinder in representative current and wave conditions in the North Sea wind farms. We used an iterative method in the experiments to ensure the same nominal sea states at the location of the installed cylinder in different current conditions for each sea state. While

Accurate knowledge of the sediment budget of a coastal cell is necessary for coastal management and predicting long-term coastal change. An important component in the sediment budget of many wave-dominated embayed coastlines is the amount of sediment that bypasses rocky headlands, which present partial barriers to alongshore transport. As yet, there is no universal method for estimating bypass rates

Landslide-tsunamis are generated by masses, such as landslides or icebergs, impacting into water bodies. Such tsunamis resulted in major catastrophes in the recent past. Generic research into landslide-tsunamis has widely been conducted in idealised water body geometries at uniform water depths. However, varying bathymetries can significantly alter landslide-tsunamis. This article investigates this