Coastal aeolian sediment transport in an active bed surface layer: Tracer study and conceptual model

Coastal aeolian sediment transport is influenced by supply-limiting factors caused by sediment sorting by grain size. Sorting processes can lead to coarsening of the bed surface and influence the formation of aeolian ripples. However, the influence sorting processes and bedforms might have on the magnitude of the transport is not fully...

Coastal Aeolian Sediment Transport in an Active Bed Surface Layer: Tracer Study and Conceptual Model

Coastal aeolian sediment transport is influenced by supply-limiting factors such as sediment sorting by grain size. Sorting processes can cause a coarsening of the bed surface and influence the formation of aeolian ripples. However, it is not fully understood what influence sorting processes have on the magnitude of this transport. In this study...

On the redistribution and sorting of sand at nourishments: Field evidence and modelling of transport processes and bed composition change

Increasingly large sand nourishments are used for the maintenance of sandy coasts around the world. There is, however, still very limited understanding of their behaviour (i.e. redistribution) and effects on the marine environment. This PhD thesis explores the morphological reshaping of shoreface nourishments (i.e. long bunds of sand placed at...

Numerical Study of Alternate Bars in Alluvial Channels With Nonuniform Sediment

Rivers typically present heterogeneous bed material, but the effects of sediment nonuniformity on river bar characteristics are still unclear. This work investigates the impact of sediment size heterogeneity on alternate bars with a morphodynamic numerical model. The model is first used to reproduce a laboratory experiment showing alternate...

Modelling of Grain Sorting Mechanisms in the Nearshore Area for Natural and Nourished Beaches

In this study a modelling approach was investigated that takes into account the effect of short wave grouping on long wave motions, calculating sediment transport and morphology with multiple fractions and a layered bed stratigraphy. After extensive testing and validating this model using data collected in a wave flume in Hannover this model was...

Development of sediment sorting near the large scale nourishment 'The Sand Motor'

The sediment composition of the sea bed is of relevance for various coastal properties such as bed forms, beach slopes and marine ecology. Furthermore it may significantly influence the morphological evolution of the coast. The sediment sorting processes at natural beaches are, however, difficult to distinguish since there can be a both a large...

Modelling sediment sorting near the large scale nourishment 'The Sand Motor': Understanding cause and impact of sediment sorting processes

The sediment composition of the sea bed is of relevance for various coastal properties such as bed forms, beach slopes and marine ecology. Furthermore it may significantly influence the morphological evolution of the coast. Knowledge about the processes forcing the spatial distribution of a certain grain size is therefore of great importance....

Sediment sorting at a large scale nourishment

A new approach in coastal maintenance is the application of a large scale nourishment as natural feeder of the coast. The Sand Motor constructed near Kijkduin on the Holland Coast is a pilot project of this new nourishment strategy. The objective of this research is to contribute to a better understanding of the sediment transport processes at...

Monitoring of beach surface properties with remote sensing

Existing aeolian transport formulae tend to overestimate the sediment transport volumes in coastal environments. Supply limiting factors like moisture content, shell patches, sediment sorting, vegetation and morphological features are believed to explain these overestimations. These supply limitations act on a variety of spatio-temporal scales...

Different approaches to handling vertical and streamwise sorting in modeling river morphodynamics

This paper presents an assessment of the strengths and weaknesses of four sediment continuity models for nonuniform sediment by applying these models to an aggradational flume experiment that is dominated by nonuniform sediment and dunes. The author makes simulations of the flume experiment using four numerical morphodynamic model systems to...

Low-mobility transport of coarse-grained material: Inventory

Experiments with graded sediments in a straight flume: Report on experimental investigations