Anouk de Bakker

Deltares · Unit: Marine and Coastal systems | Department: Applied Morphodynamics

Dunes and beaches protect large stretches of the Dutch coast against flooding from the sea. As prescribed by the Dutch Water Law, the Dutch dune coast is periodically assessed to ensure an acceptable level of flood risk in the hinterland. This safety assessment methodology is currently being renewed within the framework of the BOI program (Assessme...

During the Late Pleistocene, Dansgaard-Oeschger (DO) cycles triggered warming events that were as abrupt as the present-day human-induced warming. However, in absence of a periodic forcing operating on millennial time scales, the main energy sources of DO cycles remain debated. Here, we identify the energy sources of DO cycles by applying a bispect...

The increasingly nonlinear response of the climate–cryosphere system to insolation forcing during the Pliocene and Pleistocene, as recorded in benthic foraminiferal stable oxygen isotope ratios (δ18O), is marked by a distinct evolution in ice-age cycle frequency, amplitude, phase, and geometry. To date, very few studies have thoroughly investigated...

The increasingly nonlinear response of the climate-cryosphere system to insolation forcing during the Pliocene and Pleistocene, as recorded in benthic foraminiferal stable oxygen isotope ratios (δ¹⁸O), is marked by a distinct evolution in ice-age cycle frequency, amplitude, phase, and geometry. To date, very few studies have thoroughly investigated...

Empirical parameterizations of the shortwave sand transport that are used in practical engineering models lack the representation of certain processes to accurately predict morphodynamics in shallow water. Therefore, measurements of near-bed velocity and suspended sand concentration, collected during two field campaigns (at the Sand Engine and Amel...

Significance The Antarctic ice cap waxed and waned on astronomical time scales throughout the Oligo-Miocene time interval. We quantify geometries of Antarctic ice age cycles, as expressed in a new climate record from the South Atlantic Ocean, to track changing dynamics of the unipolar icehouse climate state. We document numerous ∼110-thousand-year-...

Short-wave sand transport in morphodynamic models is often based solely on the near-bed wave-orbital motion, thereby neglecting the effect of ripple-induced and surface-induced turbulence on sand transport processes. Here, sand stirring was studied using measurements of the wave-orbital motion, turbulence, ripple characteristics and sand concentrat...

Two field data sets of near-bed velocity, pressure, and sediment concentration are analyzed to study the influence of infragravity waves on sand suspension and cross-shore transport. On the moderately sloping Sand Motor beach (≈1:35), the local ratio of infragravity wave height to sea-swell wave height is relatively small (HIG∕HSW < 0.4), and sand...

The numerical model SWASH is used to investigate nonlinear energy transfers between waves for a diverse set of beach profiles and wave conditions, with a specific focus on infragravity waves. We use bispectral analysis to study the nonlinear triad interactions, and estimate energy transfers to determine energy flows within the spectra. The energy t...

A high-resolution data set of three irregular wave conditions collected on a gently sloping, laboratory beach is analyzed to study nonlinear energy transfers involving infragravity frequencies. We use bispectral analysis to identify the dominant nonlinear interactions and estimate energy transfers to investigate energy flows within the spectra. Ene...

Extreme storms drive change in coastal areas, including destruction of dune systems that protect coastal populations. Data from four extreme storms impacting four geomorphically-diverse barrier islands are used to quantify dune elevation change. This change is compared to storm characteristics to identify variability in dune response, improve under...

Infragravity waves (0.005–0.05 Hz) have recently been observed to dissipate a large part of their energy in the short-wave (0.05–1 Hz) surf zone, however, the underlying mechanism is not well understood. Here, we analyse two new field data sets of near-bed pressure and velocity at up to 13 cross-shore locations in ≲2.5m depth on a ≈1:80≈1:80 and a...

A good prediction of wave celerity is essential for wave propagation modeling in the nearshore. Previous studies have been focusing on the analysis of wave celerities averaged over several waves, neglecting the intra-wave variability due to long-wave transformation for instance. This paper is devoted to a study of individual wave transformation in...

An extensive new laboratory dataset, obtained on a 1:80 sloping fixed beach, is analyzed to obtain further insight into infragravity-wave propagation and dissipation. In our dataset, infragravity waves originate from the non-linear energy transfer from short waves. The previously reported change in phase lag of the infragravity waves behind the sho...

An equilibrium dune-erosion model is used every six years to assess the capability of the most seaward dune row on the Dutch Wadden islands to withstand a storm with a 1 in 10,000 probability for a given year. The present-day model is the culmination of numerous laboratory experiments with an initial cross-shore profile based on the central Netherl...