Accounting for uncertainties in forecasting tropical-cyclone-induced compound flooding

Tropical-cyclone impacts can have devastating effects on the population, infrastructure, and natural habitats. However, predicting these impacts is difficult due to the inherent uncertainties in the storm track and intensity. In addition, due to computational constraints, both the relevant ocean physics and the uncertainties in meteorological...

Modelling wave group-scale hydrodynamics on orthogonal unstructured meshes

An unstructured hydrodynamic model is presented that is able to simulate 2D nearshore hydrodynamics on the wave group scale. A non-stationary wave driver with directional spreading, with physics similar to XBeach (Roelvink et al., 2009) is linked to an improved and extended version of the existing unstructured flow solver Delft3D–FM (Kernkamp...

Wave-Driven Hydrodynamic Processes Over Fringing Reefs With Varying Slopes, Depths, and Roughness: Implications for Coastal Protection

Wave breaking on the steep fore-reef slopes of shallow fringing reefs can be effective at dissipating incident sea-swell waves prior to reaching reef shorelines. However, wave setup and free infragravity waves generated during the sea-swell breaking process are often the largest contributors to wave-driven water levels (wave runup) at the...

Coral Reef Restorations Can Be Optimized to Reduce Coastal Flooding Hazards

Coral reefs are effective natural coastal flood barriers that protect adjacent communities. Coral degradation compromises the coastal protection value of reefs while also reducing their other ecosystem services, making them a target for restoration. Here we provide a physics-based evaluation of how coral restoration can reduce coastal flooding...

Efficient two-layer non-hydrostatic wave model with accurate dispersive behaviour

A 2-layer non-hydrostatic model with improved dispersive behaviour is presented. Due to the assumption of a constant non-hydrostatic pressure distribution in the lower layer, the dispersive behaviour is improved without much additional computational time. A comparison with linear wave theory showed that this 2-layer model gives a better...

The application of a radar-based depth inversion method to monitor near-shore nourishments on an open sandy coast and an ebb-tidal delta

Coastal management in the Netherlands has the aim to defend coastal zones by preventing flooding and mitigating erosion. To that end, large-scale nourishments are placed in the nearshore, which are supposed to dynamically preserve the coastal zone over a timescale of years. To assess their effectiveness, these nourishments are monitored over...

Towards A Flood Risk Assessment On A Reef-lined Coastline

The assessment of coastal flood risk on a reef-lined coastline presents several challenges. From the probabilistic side, we need to consider all possible events that could occur in the system, taking into account the different contributions of waves, storm surges, and tides that contribute to the total water level. To estimate reliable flood...

Impact of Coral Reef Mining Pits on Nearshore Hydrodynamics and Wave Runup During Extreme Wave Events

Small island developing states are among the most vulnerable areas to the impact of natural hazards and climate change. Flooding due to storm surges and extreme waves, coastal erosion, and salinization of freshwater lenses are already a serious threat and could lead to irreversible consequences in the coming decades. Reef flat mining is one...

HyCReWW: A Hybrid Coral Reef Wave and Water level metamodel

Wave-induced flooding is a major coastal hazard on tropical islands fronted by coral reefs. The variability of shape, size, and physical characteristics of the reefs across the globe make it difficult to obtain a parameterization of wave run-up, which is needed for risk assessments. Therefore, we developed the HyCReWW metamodel to predict wave...

Undular bore development over a laboratory fringing reef

Several studies have reported the development of undular bores over fringing coral reefs (e.g, Gallagher, 1976; Nwogu and Demirbilek, 2010) but the importance of this phenomenon for reef hydrodynamics has never been studied. Yet, the transformation of a long wave (e.g., swell or infragravity wave) into an undular bore leads to significant...

A Bayesian-Based System to Assess Wave-Driven Flooding Hazards on Coral Reef-Lined Coasts

Many low-elevation, coral reef-lined, tropical coasts are vulnerable to the effects of climate change, sea level rise, and wave-induced flooding. The considerable morphological diversity of these coasts and the variability of the hydrodynamic forcing that they are exposed to make predicting wave-induced flooding a challenge. A process-based...

Identification and classification of very low frequency waves on a coral reef flat

Very low frequency (VLF, 0.001–0.005 Hz) waves are important drivers of flooding of low-lying coral reef-islands. In particular, VLF wave resonance is known to drive large wave runup and subsequent overwash. Using a 5 month data set of water levels and waves collected along a cross-reef transect on Roi-Namur Island in the Republic of the...

Modeling the effect of wave-vegetation interaction on wave setup

Aquatic vegetation in the coastal zone attenuates wave energy and reduces the risk of coastal hazards, e.g., flooding. Besides the attenuation of sea-swell waves, vegetation may also affect infragravity-band (IG) waves and wave setup. To date, knowledge on the effect of vegetation on IG waves and wave setup is lacking, while they are potentially...

Low frequency wave resonance in fringing reef environments

Low frequency wave resonance has been postulated to enhance damage to coral reef protected coastlines during storm events. This paper uses the numerical model XBeach to examine the dynamics that contribute to resonance that have been previously observed on a fringing reef on Guam during tropical storm Man-Yi (Péquignet et al., 2009). The methods...

A field numerical study into rip currents in wind-sea dominated environments

Rip currents are wave-induced and off-shore directed flows which occur frequently in the surf zone and can pose a serious threat to swimmers. While the behaviour of rip currents has been studied in swell-dominated environments, less is known about their characteristics in wind-sea dominated environments. This study aims to improve the knowledge...

Coastal inlets and tidal basins

Coastal inlets and Tidal basins