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The use of physics-based wave propagation predictions requires a considerable time commitment, a high level of expertise and extensive climate and reef data that are not always available when undertaking planning for management of coasts and coral reef ecosystems. Bayesian belief networks (BBNs) have at least three attributes that make them an excellent choice to communicate physics-based wave model predictions. First, BBNs subsume thousands of predictions to provide probabilistic outcomes. Second, by using prior probabilities, a practitioner can still obtain predictions of wave outcomes even when their knowledge of input parameters is incomplete. Third, BBNs can propagate evidence from outputs to inputs, which can be used to identify input conditions that are most likely to deliver a chosen outcome. These three attributes are tested and found to hold for a BBN developed for this purpose. [ABSTRACT FROM AUTHOR]

Measurements of coral structural strength are coupled with a fluid dynamics-structural analysis to investigate the resilience of coral to wave loading under sea level rise and a typical Great Barrier Reef lagoon wave climate. The measured structural properties were used to determine the wave conditions and flow velocities that lead to structural failure. Hydrodynamic modelling was subsequently used to investigate the type of the bathymetry where coral is most vulnerable to breakage under cyclonic wave conditions, and how sea level rise (SLR) changes this vulnerability. Massive corals are determined not to be vulnerable to wave induced structural damage, whereas branching corals are susceptible at wave induced orbital velocities exceeding 0.5 m/s. Model results from a large suite of idealised bathymetry suggest that SLR of 1 m or a loss of skeleton strength of order 25% significantly increases the area of reef flat where branching corals are exposed to damaging wave induced flows. [ABSTRACT FROM AUTHOR]

The hydrodynamic performance of an integrated oscillating water column (OWC) combined with a cylindrical caisson type breakwater was investigated. A three-dimensional numerical wave tank was established to simulate the overall energy conversion performance and hydrodynamics of the integrated system with the software Star-CCM+. The developed Computational Fluid Dynamics (CFD) model was initially verified with the published physical results and numerical results derived from an analytical solution. The effects of the structural geometry and the pneumatic damping of the PTO system on the wave absorption and power conversion efficiency of the proposed device were investigated using this developed model. Based on this proposed numerical model, the velocity of the air flow, the corresponding air pressure characteristics in the air turbine nozzle and chamber zone were discussed. The results indicate that this proposed half-open land based OWC is adapted to absorb shorter nearshore waves, characterized by dimensionless wave number kd approaching 1.49. Furthermore, a larger opening inlet zone for this proposed OWC would shift the resonant corresponding kd to higher wave frequencies, while lowering the opening inlet could help to increase the power extraction efficiency for long waves. The peak hydrodynamic efficiency is observed at a ratio of OWC inlet width to diameter B / D of 0.97, which is approximately six times larger than that at B / D = 0.5. The inclusion of an impulse turbine yields a more uniform pressure distribution within the central chamber and effectively mitigates wave reflection for smaller incident waves, with maximum efficiency achieved using 37 blades. The property of the efficiency mitigation with insufficient certain intake depth of the wave chamber should be avoided for system design. • A novel dual cylindrical OWC incorporated into a fixed caisson type breakwater was numerically investigated. • The effects of the chamber geometry and the PTO damping on the primary-stage power conversion efficiency are studied. • The flow field of the hybrid system in and around the OWC chamber is investigated. • The effect of impulse turbine on the secondary-stage performance as well as efficiency is considered. [ABSTRACT FROM AUTHOR]

In this paper we synthesise a large data set gathered from a wide variety of field deployments and integrate it with previously published results to identify the spectral signatures of swash from contrasting beach types. The field data set includes the full range of micro-tidal beach types (reflective, intermediate and dissipative), with beach gradients ranging from approximately 1:6 to 1:60 exposed to offshore significant wave heights of 0.5-3.0 m. The ratio of swash energy in the short-wave (f > 0.05 Hz) to long-wave (f < 0.05 Hz) frequency bands is found to be significantly different between the three beach types. Swash energy at short-wave frequencies is dominant on reflective and intermediate beaches and swash at long-wave frequencies is dominant on dissipative beaches; consistent with previously reported spectral signatures for the surf zone on these beach types. The available swash spectra were classified using an automated algorithm (CLARA) into five different classes. The ordered classes represent an evolution in the spectrum shape, described by a frequency downshifting of the energy peak from the short-wave into the long-wave frequency band and an increase in the long-wave swash energy level compared to a relatively minor variation in the short-wave swash energy level. A universally common feature of spectra from all beach-states was an f- 4energy roll-off in the short-wave frequency band. In contrast to the broadly uniform appearance of the short-wave frequency band, the appearance of the long wave frequency band was highly variable across the beach-states. We incorporate the results presented here and previously published observations into the morphodynamic beach-state model, and propose an ordered sequence of swash spectra under increasing and decreasing incident wave energy level. This extension of the beach-state model to include the swash zone leads to the following propositions for morphodynamic controls on the nature of the swash spectrum. (1) The short-wave part of the swash spectrum is relatively constant in form across all beach-states (f- 4 energy roll-off) and the energy density per unit frequency is controlled by the beach face gradient alone. (2) The spectral bandwidth of the energy roll-off varies directly with offshore wave energy level and inversely with beach face gradient (or beach-state), in a manner consistent with the non-linear wave breaking criterion. (3) The infragravity part of the swash spectrum is highly variable in form across all beach-states and the energy level is related to the offshore wave energy level and surf zone morphology. [ABSTRACT FROM AUTHOR]

Abstract: This study documents two different modes of berm development: (1) vertical growth at spring tides or following significant beach cut due to substantial swash overtopping, and (2) horizontal progradation at neap tides through the formation of a proto-berm located lower and further seaward of the principal berm. Concurrent high-frequency measurements of bed elevation and the associated wave runup distribution reveal the details of each of these berm growth modes. In mode 1 sediment is eroded from the inner surf and lower swash zone where swash interactions are prevalent. The net transport of this sediment is landward only, resulting in accretion onto the upper beach face and over the berm crest. The final outcome is a steepening of the beach face gradient, a change in the profile shape towards concave and rapid vertical and horizontal growth of the berm. In mode 2 sediment is eroded from the lower two-thirds of the active swash zone during the rising tide and is transported both landward and seaward. On the falling tide sediment is eroded from the inner surf and transported landward to backfill the zone eroded on the rising tide. The net result is relatively slow steepening of the beach face, a change of the profile shape towards convex, and horizontal progradation through the formation of a neap berm. The primary factor determining which mode of berm growth occurs is the presence or absence of swash overtopping at the time of sediment accumulation on the beach face. This depends on the current phase of the spring-neap tide cycle, the wave runup height (and indirectly offshore wave conditions) and the height of the pre-existing berm. A conceptual model for berm morphodynamics is presented, based on sediment transport shape functions measured during the two modes of berm growth. [Copyright &y& Elsevier]

Submerged nearshore structure designs are commonly tested and optimised in scale model wave basins prior to construction in the field. Depending on the purpose of the structure, different measurement methods are used. In this paper, a camera-based measurement method called Wave Peel Tracking (WPT) was adapted and evaluated for quantifying wave breaking over submerged structures purposed for surf amenity. The WPT algorithm was successfully applied to the wave basin through controlled artificial lighting at night, precise image rectification, and modification to a classifier model. The WPT results were verified using overhead footage and had similar accuracy to the WPT algorithm previously applied in the field (Thompson et al., 2021a). Results from wave basin testing of two rock reef structures and three sand mound structures are presented for both regular and irregular waves and were analysed to show the effectiveness of the WPT algorithm in quantifying surf amenity for informing design optimisation. The algorithm applied to the wave basin is open-source, enabling further use and adoption by other laboratories. • Open-source software tracks surfable rides in a wave basin. • 2 rock reef and 3 sand mound physical models were assessed for surf amenity. • WPT results revealed how surf amenity was created in different ways. [ABSTRACT FROM AUTHOR]

This is the first study to undertake a comprehensive parametric study of wave-induced scour around a large bluff body structure, and also presents experimental data to validate a CFD model for wave-induced scour around the structure. A parametric study is undertaken using the REEF3D CFD model for varying incident wave condition (depth, wave amplitude, frequency, and direction), structure geometry (width, length, and corner curvature), and sediment size. The numerical model is validated against experimental datasets, demonstrating that the model can accurately replicate scour around large bluff body structures. Two new equations are proposed for prediction of non-dimensional equilibrium scour depths at the front and back corners of a large bluff body structure using the Keulegan-Carpenter (KC) number based on 18 and 24 datapoints respectively. The equations are valid within the following limits: 0.37 ≤ KC ≤ 1.75, 0.10 ≤ B/λ p and 0.14 ≤ L/λ p , where B and L are the structure width and streamwise length, and λ p is the peak wave length. It is further demonstrated that the non-dimensional scour depth does not vary significantly with the sediment size (for 0.075 ≤ θ ≤ 0.117 where θ is the Shields parameter), or the structure width/length for the limits stated above. • Parametric study of wave-induced scour around a large bluff body structure. • Numerical model validated against original and existing experimental datasets. • Two new equations proposed for scour prediction at corners of a large bluff body. • Equilibrium scour depth for live-bed regime shown not to vary with sediment size. [ABSTRACT FROM AUTHOR]

• Scour patterns measured experimentally around a scaled Oscillating Water Column. • Scour shown to undermine the structure, comparable with the tunnel erosion effect. • Undermining scour leads to settlement of the gravity-based structure. • Increasing the corner curvature shown to reduce scour depths by 23%. • Comparison with field observations reveals similar scour patterns. Experimental measurements of wave scour are reported for a 1:20 scaled model of an operating 200 kW Oscillating Water Column (OWC) Wave Energy Converter (WEC) in King Island, Tasmania, Australia. Test cases include different wave conditions (Keulegan-Carpenter (KC) number range of 0.45-1.02) and multiple geometric changes to the device, which are compared to scour measurements taken in the field around the King Island OWC WEC device. The measurements therefore provide the first ever comparison of field data with a scaled laboratory model of scour around an OWC WEC. Results highlight that scour forms at the back corners of the device before undermining the structure with depths up to 64 mm (scour depth to structure width ratio, S / B , of 0.094), although the magnitude of this scour is shown to be reduced by 23% by curving the back corners. Scour at the front of the device is highly sensitive to the configuration of the front chamber door, with very different scour scenarios depending on whether the chamber door is open, closed, or removed entirely. Comparison with field data shows that undermining scour at the back of the device is reproduced in both settings, and this leads to settlement of the structure in both the laboratory and field. This suggests that the physical modelling forms an accurate representation of a real-world site, and therefore demonstrates scour processes with applicability to OWC WECs and other gravity-based bluff body structures such as caissons or gravity-based foundations. [ABSTRACT FROM AUTHOR]