Detailed simulation of morphodynamics: 3. Ripples and dunes

We present a 3-D physics-based high-resolution modeling approach to the dynamics of underwater ripples and dunes. The flow is modeled by large eddy simulation on a Cartesian grid with local refinements. The sediment transport is modeled by computing pickup, transport over the bed, transport in the water column, and deposition of rigid spherical...

Physics of Blown Sand and Coastal Dunes

Detailed simulation of morphodynamics: 1. Hydrodynamic model

We present a three-dimensional high-resolution hydrodynamic model for unsteady incompressible flow over an evolving bed topography. This is achieved by using a multilevel Cartesian grid technique that allows the grid to be refined in high-gradient regions and in the vicinity of the river bed. The grid can be locally refined and adapted to the...

The interaction between bed-load transport and dune orientation

Bedforms play an important role in the sediment transport of a river. Because of their importance many experiments have been carried out to better understand bedforms. Most experiments concern transverse bedforms (with crests aligned perpendicular to the flow direction). However, bathymetry measurements show many instances of oblique dunes....

Process-based modeling of coastal dune development

In this paper, the aeolian transport model DUNE (Sauermann et al., 2001, Kroy et al., 2002) that describes important features and dynamics of typical desert dunes, is extended such that it can be applied in sandy coastal areas. Initial tests explore the limitations of the model in coastal areas after which adaptations are proposed and...

Process-based Modeling of Coastal Dune Development

This thesis presents the application of an aeolian transport model used in desert environments [Sauermann et al., 2001, Kroy et al., 2002] as a tool for the evolution of coastal nourishments. This study will try to investigate the driving processes in the model and adapt or extend the model application to the coastal system. If we want to apply...

Modelling the 1775 storm surge deposits at the Heemskerk dunes

After a storm surge in November 2007, older storm surge deposits were discovered in the eroded dunes near Heemskerk, the Netherlands. These deposits undulate in height with a maximum elevation of over 6 m above mean sea level. Luminescence dating suggests that the layers were deposited by either the 1775 or the 1776 storm surge. The aim of this...

Numerical modeling of wave overwash on low-crested sand barriers

For management of coastal breaching hazards it is critical to be able to assess the potential of coastal barrier breaching as a result of wave actions during storm surges (wave overwash). This phenomenon is known as the breach initiation phase; the mechanisms behind this are not very well understood. In the present study, laboratory experiments...

A model for breach growth in a sand-dike and its prediction for the Zwin 94 experiment

A mathematical model for breach growth in sand-dikes and dunes is described. The model is based on the five-step breach erosion process as observed in several laboratory experiments and the Zwin 89 field experiment. A simplified Galappatti (1983) pick up mechanism for sand from the bed is combined with Bagnold's (1963) modified (Visser, 1988)...

Coastal Protection and Dune Management in the Netherlands

Because dunes protect a large part of The Netherlands against coastal flooding and inundation, it is vital to guarantee the strength of these natural sea defenses. Besides sea defense, dunes have other functions. Sandy shorelines and dunes are frequently eroded. A legal framework has been developed that guarantees the required safety-level of...

Sea defence and flood protection in the Netherlands anticipating increased sea-level rise

The 1400 km Dutch coastline is affected by sea-level rise. At this moment a legal framework is made to guarantee safety of the dikes also in future. Also a national policy is developed for compensation of all coastal erosion. Both measures should make it possible for the Netherlands to survive an increased sea-level rise.

Water movement over a horizontal bed and solitary sand dunes

In order to predict waterlevel changes in rivers due to floodwaves and local bedshapes for navigation, the local behaviour of the riverbed should be known . In many cases the bed of 3 river consists of dunes, which propagate downstream due to the sediment transport along the dunes . In this report mainly the watermovement but also the sediment...