A new morphological schematization of the Western Scheldt estuary, The Netherlands

The present paper describes an analysis of the morphological integrityof the multiple channel system (MCS) of the Western Scheldt estuary. The tidal flats and surrounding ebb and flood channels form morphological cells, and the entire MCS can be schematized as a chain of such cells. The major ebb and flood channels have lost their one time...

Stratification effects by fine suspended sediment at low, medium, and very high concentrations

This paper describes results of the second part of a study on stratification effects by cohesive and noncohesive sediment. Winterwerp (2001) applied classical stratified flow theory implemented in a one-dimensional vertical numerical model (the 1DV POINT MODEL), showing that sediment-induced stratification effects may occur at already fairly...

Influence of shear rate, organic matter content pH and salinity on mud flocculation

A stochastic formulation for erosion of cohesive sediments

The linear formulation for erosion E = M(?b??c), often applied in engineering applications, has two properties, which do not always comply with field and laboratory observations, they are as follows: (1) The erosion rate is zero below the critical bed shear stress ?c and increases linearly with bed shear stress ?b, when exceeding the critical...

Fine sediment dynamics in a shallow lake and implication for design of hydraulic works

Lake Markermeer is a large (680 km2), shallow body of water in the middle of the Netherlands, with a mean water depth of 3.6 m. One of the major problems in the lake is its decreasing ecological value which is, among other reasons, caused by a gradual increase of suspended sediment concentration and associated increase of light attenuation in...

Fine sediment transport by tidal asymmetry in the high-concentrated Ems River: Indications for a regime shift in response to channel deepening

This paper describes an analysis of the observed up-river transport of fine sediments in the Ems River, Germany/Netherlands, using a 1DV POINT MODEL, accounting for turbulence-induced flocculation and sediment-induced buoyancy destruction. From this analysis, it is inferred that the net up-river transport is mainly due to an asymmetry in...

The effects of the internal flow structure on SPM entrapment in the Rotterdam Waterway

Field measurements are presented, which are the first to quantify the processes influencing the entrapment of suspended particulate matter (SPM) at the limit of saltwater intrusion in the Rotterdam Waterway. The estuarine turbidity maximum (ETM) is shown to be maintained by the trapping of fluvial SPM at the head of the salt wedge. The trapping...

Advection of the salt wedge and evolution of the internal flow structure in the Rotterdam Waterway

An analysis of field measurements recorded over a tidal cycle in the Rotterdam Waterway is presented. These measurements are the first to elucidate the processes influencing the along-channel current structure and the excursion of the salt wedge in this estuary. The salt wedge structure remained stable throughout the measuring period. The...

Regime shifts in muddy open water systems

Sediment dynamics in Lagos Harbour reconnaissance on effects of dredging

Due to economic growth, Lagos Harbour is expanding. Capital dredging is needed to allow larger vessels to call the port. As harbour siltation is already a problem, increase of maintenance dredging is a worry. In the past no data was available to understand the hydraulics and sediment transport to estimate maintenance dredging volumes. This paper...

On the hindered settling of silt-water mixtures

The sedimentation behavior of silt particles in the hindered settling regime has been considered. Therefore, laboratory experiments are carried in especially designed settling columns. Silt-water mixtures are prepared and allowed to settle at various initial concentrations. During the settling process, a continuous vertical concentration profile...

A conceptual framework for shear flow–induced erosion of soft cohesive sediment beds

This paper proposes a conceptual framework for erosion of cohesive sediment beds. We focus on cohesive beds, distinguishing between floc erosion, surface erosion, and mass erosion. By (our) definition, surface erosion is a drained soil mechanical process, whereas mass erosion occurs under undrained conditions. The eroding shear stress is modeled...

Fine sediment transport into the hyperturbid lower Ems River: The role of channel deepening and sediment-induced drag reduction

Deepening of estuarine tidal channels often leads to tidal amplification and increasing fine sediment import. Increasing fine sediment import, in turn, may lower the hydraulic drag (due to a smoother muddy bed and/or sediment-induced damping of turbulence), and therefore, further strengthen tidal amplification, setting in motion a process in...

Effect of algae on flocculation of suspended bed sediments in a large shallow lake. Consequences for ecology and sediment transport processes

Lake Markermeer, a large shallow lake in The Netherlands, suffers from turbidity and ecology problems. As part of a study aiming to mitigate these problems, we study flocculation processes in the lake; in particular, the possible mutual flocculation between algae and re-suspended bed sediments. We show that sediment re-suspended from the bed of...

Efficiency of hanging silt curtains in cross-flow

When dredging in sensitive environments, efforts have to be made to limit the free dispersal of suspended fine sediment from the dredging spill. Especially the use of hanging silt curtains as an environmental mitigation measure is widespread. Despite frequent application, their ability to reduce turbidity levels through vertical diversion of...

How human activities affect the fine sediment distribution in the Dutch Coastal Zone seabed

The fine sediment distribution in the seabed is an important indicator for the ecological functioning of shallow coastal seas. In this paper, we investigate the processes and conditions that determine the fine sediment distribution in the Dutch coastal zone surficial seabed, while also assessing the response of the system to human...

An explanatory model for the burial of fines in the sandy seabed of the southern North Sea

The amount of suspended fines in the southern North Sea strongly depends on their exchange with the sandy seabed. This exchange is governed by resuspension of fines during storms, followed by burial in the week thereafter. Despite its importance for fine sediment dynamics, the burial of fines into a sandy seabed is currently not well...