Stationary-phase analysis of time-shift extended imaging in a constant-velocity model

To estimate the depth errors in a subsurface model obtained from the inversion of seismic data, the stationary-phase approximation in a two-dimensional constant-velocity model with a dipped reflector is applied to migration with a time-shift extension. This produces two asymptotic solutions: one is a straight line, and the other is a curve....

Performance of old and new mass-lumped triangular finite elements for wavefield modelling

Finite elements with mass lumping allow for explicit time stepping when modelling wave propagation and can be more efficient than finite differences in complex geological settings. In two dimensions on quadrilaterals, spectral elements are the obvious choice. Triangles offer more flexibility for meshing, but the construction of polynomial...

Temporal dispersion correction for wave-propagation modelling with a series approach

Temporal dispersion correction of second-order finite-difference time stepping for numerical wave propagation modelling exploits the fact that the discrete operator is exact but for the wrong frequencies. Mapping recorded traces to the correct frequencies removes the numerical error. Most of the implementations employ forward and inverse...

Change of nearshore extreme wind and wave climate in southeast Africa

L'uso eccessivo di combustibili fossili sta causando la riduzione delle riserve di carbone, oltre ad un aumento delle emissioni di gas “effetto serra” esacerbando i cambiamenti climatici. Tali condizioni alterano la circolazione dei venti sugli oceani e, di conseguenza, il clima ondoso, con effetti non solo sui regimi medi, ma anche sugli...

Momentum Balance Across a Barrier Reef

This paper reports on a combined experimental and numerical study dedicated to barrier reefs hydrodynamics. A network of pressure sensors and velocity profilers has been deployed for more than 2 months over the Ouano reef barrier, New Caledonia. The primary aim of the study is to assess the relevance of the classical depth-averaged momentum...

Modelling of Cohesive Sediment Transportation, Deposition and Resuspension in the Haringvliet Mouth.

In the Dutch coastal zone, where the marine environment is characterized by shallow depths and highly energetic hydrodynamic conditions, the cohesive sediments, or mud, play an important role in the local morphology. For instance, mud deposits and high concentrations of suspended particulate matter (SPM) occur frequently, especially during...

Measuring Programme Amelander Zeegat Storm Season 2003-2004: Measurement report on two northwesterly storms

Primary water defences protect the Netherlands against flooding by the North Sea, the major rivers and inland seas Markermeer and IJsselmeer. The Dutch Water Defence Act [Wet op de Waterkering] stipulates that these water defences have to be tested every five years to determine if they guarantee the statutory safety level with respect to the...

The Archimedes Wave Swing

Transfer of ocean modelling capability to two scientists of the National Institute of Oceanography of India

Two scientists from the National Institute of Oceanography of India have been trained to use the storm surge model DUCHESS and the wave model DOLPHIN. The results are published separately in two reports. This is the first of them.

Selection and formulation of a numerical shallow water wave hindcast model

Formulate a numerical wave hindcast model which can be used to obtain realistic estimates of wave conditions in the Oosterschelde as input to a numerical geomorphological model. A directionally decoupled, parametric wave hindeast model is recommended that includes parameterized versions of conventional bottom- and current refraction, some degree...

Waves and their effects on pile-supported structures

Three methods of presenting wave data are discussed: the significant wave (including the "design wave" concept), the wave spectrum, and the directional spectra. Their use in calculating wave forces on pile supported structures is described, with a discussion of the relative usefulness of the linear versus the non-linear approach. The concept of...

A comparison of regular and wind-generated wave action on rubble-mound breakwaters

The general purpose of this research is to study wave action on rubble mound breakwaters with periodic waves on the one hand, and random wind generated Waves on the other hand, and to compare the effects of these two types of waves by use of the storm duration. With the first series of periodic waves experiments, we obtained the destruction of...

Symposium "Research on wave action"

Symposium organised at Delft Hydraulics on the development of research in waves and wave structure interaction.

Wave shock forces: An analysis on deformations and wave forces in the wave and the foundation

At the inauguration of two advanced wind-wave flumes in the Netherlands, three decades after BAGNOLD's pioneer work, and one decade after the Haringvliet sluice investigation and the joint Dutch-Danish investigation of the Hanstholm breakwaters, it seems appropriate to summarize current knowledge on wave shock phenomena. These may be classified...