Ap van Dongeren

Deltares · Department of Marine and Coastal Systems

Infragravity (IG) waves are important drivers of extreme run‐up, morphological changes, and seiches. While locally forced IG waves have been extensively investigated, recent studies have revealed the significance of free IG waves generated on distant beaches. This study focuses on free IG waves generated at a coast facing southeast in Japan during...

https://storymaps.arcgis.com/stories/7384e6551be54d9393d64d9564ec1c7b The FHICS project, led by DeltaresUSA, Deltares, and IHE Delft, focuses on forecasting the impacts of hurricanes on U.S. coastal regions. The project employs innovative modeling tools, including Delft-FIAT, HurryWave, SFINCS, and Xbeach, to predict coastal flooding, erosion, and...

Accurate flood risk assessments and early warning systems are needed to protect and prepare people in coastal areas from storms. In order to provide this information efficiently and on time, computational costs need to be kept as low as possible. Reduced-complexity models using linear inertial equations and subgrid approaches have been used previou...

More than 10 % of the world's population lives in coastal areas that are less than 10 m above sea level (also known as the low-elevation coastal zone – LECZ). These areas are of major importance for local economy and transport and are home to some of the richest ecosystems. At the same time, they are quite susceptible to extreme storms and sea leve...

Infragravity waves may contribute significantly to coastal flooding, especially during storm conditions. However, in many national and continental to global assessments of coastal flood risk, their contribution is not accounted for, mostly because of the high computational expense of traditional wave-resolving numerical models. In this study, we pr...

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 forci...

Around 10 percent of the world's population live in coastal areas that are less than 10 meters above sea level (also known as the low elevation coastal zone – LECZ). Coastal zones are therefore of major importance for local economy, transport and are home to some of the richest ecosystems. This makes coastal zones quite susceptible to extreme storm...

Tropical cyclone impacts can have devastating effects on the population, infrastructure, and on 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 fo...

Coral reefs are effective natural barriers that protect adjacent coastal communities from hazards such as erosion and storm-induced flooding. However, the degradation of coral reefs compromises their efficacy to protect against these hazards, making degraded reefs a target for restoration. At present, there is little guidance on how and where to re...

Sandy beaches and dune systems have high recreational and ecological value, and they offer protection against flooding during storms. At the same time, these systems are very vulnerable to storm impacts. Process-based numerical models are presently used to assess the morphological changes of dune and beach systems during storms. However, such model...

Sandy beaches and dune systems have high recreational and ecological value, while they offer protection against flooding during storms. At the same time, these systems are very vulnerable to storm impacts. Process-based numerical models are presently used to assess the morphological changes of dune and beach systems during storms. However, such mod...

A new set of empirical formulations has been derived to predict wave run-up at naturally sloping sandy beaches. They are obtained by fitting the results of hundreds of XBeach-NH+ model simulations. The simulations are carried out over a wide range of offshore wave conditions (wave heights ranging from 1 to 12 m and periods from 6 to 16 s), and surf...

Dune erosion driven by extreme marine storms can damage local infrastructure or ecosystems and affect the long-term flood safety of the hinterland. These storms typically affect long stretches (∼100 km) of sandy coastlines with variable topo-bathymetries. The large spatial scale makes it computationally challenging for process-based morphological m...

This review focuses on recent advances in process-based numerical models of the impact of extreme storms on sandy coasts. Driven by larger-scale models of meteorology and hydrodynamics, these models simulate morphodynamics across the Sallenger storm-impact scale, including swash, collision, overwash, and inundation. Models are becoming both wider (...

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 ad...

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 sur...

SFINCS, a new reduced-physics solver to compute compound flooding in coastal systems due to fluvial, pluvial, tidal, wind- and wave-driven processes in a computationally efficient way, is presented and validated for a number of verification and application cases. The model solves simplified equations of mass and momentum, which are driven by storm...

Considering the likely increase in coastal flooding in small island developing states (SIDSs) due to climate change, coastal managers at the local and global levels have been developing initiatives aimed at implementing disaster risk reduction (DRR) and adaptation measures. Developing science-based adaptation policies requires accurate coastal floo...

Sea level rise (SLR) will cause shoreline retreat of sandy coasts in the absence of sand supply mechanisms. These coasts have high touristic and ecological value and provide protection of valuable infrastructures and buildings to storm impacts. So far, large-scale assessments of shoreline retreat use specific datasets or assumptions for the geophys...

Climate change driven sea level rise (SLR) is expected to rise with even higher rates during the second half of the present century. This will exacerbate shoreline retreat of sandy coasts, which comprise one third of the global coastline. Sandy coasts have high touristic and ecological value while they are the first level of defense against storms,...

The importance of explicitly modelling sea-swell waves for runup was examined using a 2D XBeach short wave-averaged (surfbeat, “XB-SB”) and a wave-resolving (non-hydrostatic, “XB-NH”) model of Roi-Namur Island on Kwajalein Atoll in the Republic of Marshall Islands. Field observations on water levels, wave heights, and wave runup were used to drive...

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 large...

Tropical coral reef-lined coasts are exposed to storm wave-driven flooding. In the future, flood events during storms are expected to occur more frequently and to be more severe due to sea-level rise, changes in wind and weather patterns, and the deterioration of coral reefs. Hence, disaster managers and coastal planners are in urgent need of decis...

The open-source program Delft Dashboard (DDB) is a graphical user interface designed to quickly create, edit input parameters and visualize model inputs for a number of hydrodynamic models, using private or publicly available local and global datasets. It includes a number of toolboxes that facilitate the generation of spatially varying inputs. The...

Abstract. Considering the likely increase of coastal flooding in Small Island Developing States (SIDS), coastal managers at the local and global level have been developing initiatives aimed at implementing Disaster Risk Reduction (DRR) measures and adapting to climate change. Developing science-based adaptation policies requires accurate coastal fl...

Nearshore slope, defined as the cross-shore gradient of the subaqueous profile, is an important input parameter which affects hydrodynamic and morphological coastal processes. It is used in both local and large-scale coastal investigations. However, due to unavailability of data, most studies, especially those that focus on continental or global sc...

The accurate prediction of a barrier island response to storms is challenging because of the complex interaction between hydro- and morphodynamic processes that changes at different stages during an event. Assessment of the predictive skill is further complicated because of uncertainty in the hydraulic forcing, initial conditions, and the parameter...

We live on a blue planet, and Earth’s waters benefit many sectors of society. The future of our blue planet is increasingly reliant on the services delivered by marine, coastal and inland waters and on the advancement of effective, evidence-based decisions on sustainable development. ‘Oceans and Society: Blue Planet’ is an initiative of the Group o...

Nearshore slope, defined as the cross-shore gradient of the subaqueous profile, is an important input parameter which affects hydrodynamic and morphological coastal processes. It is used in both local and large-scale coastal investigations. However, due to unavailability of data, most studies, especially those that focus on continental or global sc...

The degradation of coastal habitats, particularly coral reefs, raises risks by increasing the exposure of coastal communities to flooding hazards. The protective services of these natural defenses are not assessed in the same rigorous economic terms as artificial defenses, such as seawalls, and therefore often are not considered in decision making....

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 of the...

An increase of the global mean sea level has already been observed and it is expected to continue with even higher rates during the second half of the present century. This can lead to sandy shoreline retreat and permanent and increased episodic inundation of parts of the coastal zone. In order to protect human lives and assets, adaptation measures...

Wave transformation across reef platforms strongly controls sediment transport processes and coral reef island morphodynamics with infragravity (IG) waves playing an important contributing role. A small‐scale (1:50) laboratory experiment and prototype numerical modeling are used to explore the characteristics of IG wave motion on coral reefs. The s...

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 run-...

In the light of challenges raised by a changing climate and increasing population pressure in coastal regions, it has become clear that theoretical models and scattered experiments do not provide the data we urgently need to understand coastal conditions and processes. We propose a Dutch coastline observatory named ICON.NL, based at the Delfland Co...

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 modificat...

Wave-driven water level variability (and runup at the shoreline) is a significant cause of coastal flooding induced by storms. Wave runup is challenging to predict, particularly along tropical coral reef-fringed coastlines due to the steep bathymetric profiles and large bottom roughness generated by reef organisms, which can violate assumptions in...

Sea levels are rising, with the highest rates in the tropics, where thousands of low-lying coral atoll islands are located. Most studies on the resilience of these islands to sea-level rise have projected that they will experience minimal inundation impacts until at least the end of the 21st century. However, these have not taken into account the a...

Free access on this link until April 25, 2018 https://authors.elsevier.com/a/1WgCn1M2DU~hr3 Coastal zones are under increasing risk as coastal hazards increase due to climate change and the consequences of these also increase due to on-going economic development. To effectively deal with this increased risk requires the development of validated t...

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 wave-re...

Recent and historic low-frequency, high-impact events have demonstrated the flood risks faced by exposed coastal areas in Europe and beyond. These coastal zone risks are likely to increase in the future which requires a re-evaluation of coastal disaster risk reduction (DRR) strategies and a new mix of PMP (prevention, e.g., dike protection; mitigat...

Under natural conditions, barrier islands might grow vertically and migrate onshore under the influence of long-term sea level rise. Sediment is transported onshore during storm-induced overwash and inundation. However, on many Dutch Wadden Islands, dune openings are closed off by artificial sand-drift dikes that prevent the influx of sediment duri...

Rip currents are one of the most dangerous coastal hazards for swimmers. In order to minimize the risk, a coastal operational-process based-model system can be utilized in order to provide forecast of nearshore waves and currents that may endanger beach goers. In this paper, an operational model for rip current prediction by utilizing nearshore bat...

Hurricane Sandy destroyed coastal areas along the Atlantic Coast of the U.S.A. upon making landfall on 29 October 2012. High storm surge and waves caused severe overwash and breaching on both uninhabited and developed barrier islands. In this study, we evaluate the extent to which erosion is affected by infrastructure using the numerical model XBea...

at Virginia Tech for providing computational resources and technical support that have contributed to the results reported within this paper, http://www.arc.vt.edu. 2 Abstract Global sea levels have risen at a rate of 1.7 mm/year over the last century and are projected to rise an additional 0.2 m to 2.0 m by 2100 with some regions experiencing high...

Rocky reef coastlines typically feature highly variable and often abrupt cross-shore and alongshore changes in bathymetry. The effects of this irregular rocky bathymetry on the dynamics of infragravity waves are largely unknown. Most models of infragravity wave dynamics have been developed and validated on smooth alongshore-uniform bathymetries, wh...

Final policy brief from the Resilience Increasing Strategies for Coasts - Toolkit (RISC-KIT) summarizing key recommendations for policy makers from the implementation of the toolkit in 10 European cities.

This chapter discusses the modeling of morphodynamical storm impacts on coasts. It gives an overview of classes of models, the physical processes that each class resolves, and the model class applicability on the different coastal environments such as sandy, gravel and coral/rock coasts, as well as coasts with hard structures and vegetation. With r...

Waves travel from deep water through intermediate depths into shallow regions, where they encounter the coastline, possibly with islands, headlands, estuaries, tidal flats, reefs, and harbors. In the shallow water region, the wave propagation is complex. Horizontal variations in the bathymetry cause shoaling, refraction, wave‐energy redistribution,...

This Synthesis Report provides an overview of the achievements, lessons learned and challenges identified through the RISC-KIT project activities, including the development and application of the tools at ten case study sites in a range of coastal regions across Europe. The lessons learned are then fed into a series of recommendations for improved...

Low frequency, high impact storm events can have large impacts on sandy coasts. The physical processes governing these impacts are complex because of the feedback between the hydrodynamics of surges and waves, sediment transport and morphological change. Predicting these coastal changes using a numerical model requires a large amount of computation...

Coastal canopies formed by aquatic vegetation (e.g. seagrass, mangroves) or corals can be found along many coastlines worldwide and often have a significant effect on the local wave dynamics. Over the past several decades, many studies have greatly increased our understanding on the physical interaction between coastal canopies and waves in the coa...

Implementation of aquatic vegetation effects into XBeach, application to sea-swell waves, infragravity waves and wave setup.

High-impact storm events have demonstrated the vulnerability of coastal zones in Europe and beyond. These impacts are likely to increase due to predicted climate change and ongoing coastal development. In order to reduce impacts, disaster risk reduction (DRR) measures need to be taken, which prevent or mitigate the effects of storm events. To drive...

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 five-month dataset of water levels and waves collected along a cross-reef transect on Roi-Namur Island in the Republic of the Marshall...

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 imp...