Settling and consolidation of mud/sand mixtures

Torfs, Hilde; Mitchener, Helen; Huysentruyt, Heidi; Toorman, Erik

doi:10.1016/s0378-3839(96)00013-0

Cited by 81 publications

(56 citation statements)

References 4 publications

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“…Within the settling column arrangement employed in the current study, the typical sedimentation and bed formation processes displayed by different sand-clay mixtures are essentially one-dimensional, with the downward movement of sediments and the upward displacement of pore fluid (Torfs et al 1996). With differential settling effects between the sand and clay fractions in the mixtures, it would be expected that larger, denser sand particles should settle faster than smaller, less-dense clay flocs, leading to a segregated bed deposit [i.e.…”

Section: Qualitative Observations On Sand-clay Segregationmentioning

confidence: 99%

“…Winterwerp 2002;Cuthbertson et al 2008; Van and Pham Van Bang 2013) and consolidation (e.g. Toorman and Berlamont 1993;Torfs et al 1996;Grasso et al 2014) processes that can lead to the formation of segregated, layered structures within the resulting bed deposits. These mixed sediment processes, and their role in defining the nature of the developing bed structure, are therefore also crucial for determining its subsequent resistance to erosion (e.g.…”

Section: Previous Work On Sand-mud Sedimentationmentioning

confidence: 99%

“…These mixed sediment processes, and their role in defining the nature of the developing bed structure, are therefore also crucial for determining its subsequent resistance to erosion (e.g. Torfs et al 1996;te Slaa et al 2013).…”

Section: Previous Work On Sand-mud Sedimentationmentioning

confidence: 99%

“…segregation) (e.g. Torfs et al 1996). In this context, sedimentation poses significant economic, environmental and societal impacts on these sensitive aquatic environments through, for example, siltation of navigation channels, harbours and ports, increased coastal flood risk, loss of intertidal habitat and ecosystems and reduction in water quality (e.g.…”

Section: Introductionmentioning

confidence: 99%

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Monitoring and characterisation of sand-mud sedimentation processes

et al. 2016

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Estuaries and tidal inlets are often characterised by the presence of both cohesive and non-cohesive sediments. Knowledge of the sedimentation behaviour of sand-mud mixtures is therefore crucial to the understanding and prediction of the time-dependent structure (i.e. mixed or segregated), composition and erodibility of sediment bed deposits developing within these environments. In the current study, a series of settling column tests are conducted to investigate the hindered settling and initial bed consolidation phases of a range of sandclay mixtures to determine the parametric conditions under which bed segregation occurs. A new, non-invasive, electrical resistivity measurement technique is employed to capture both temporal and spatial changes in the density, porosity and composition of the evolving sand-clay bed deposits, complimented by time-lapsed images of the sedimentation process within the column. The results show that the formation of segregated (sand-clay) bed layers with bed deposits is largely controlled by the initial fractional composition (i.e. relative sand and clay concentrations). Specifically, mixtures with low clay contents are shown to form well-defined (sandclay) layer segregation within the resulting deposits, while higher clay contents result in more transitional segregation patterns or no layer segregation (for very high clay concentrations). The physical mechanisms under which these different segregation types can be generated are illustrated through predictions from an existing polydisperse hindered settling model. This model indicates that the degree of bed segregation, and time scale over which this occurs, correlates well with the difference in predicted hindered settling characteristics and upward displacements associated with the sand and clay fractions, respectively. In this regard, the new experimental dataset provides validation for the polydisperse model (for the first time), with the combined data and model predictions providing new insight into mixed (sand-clay) sedimentation processes.

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Section: Qualitative Observations On Sand-clay Segregationmentioning

confidence: 99%

Section: Previous Work On Sand-mud Sedimentationmentioning

confidence: 99%

Section: Previous Work On Sand-mud Sedimentationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Monitoring and characterisation of sand-mud sedimentation processes

et al. 2016

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“…The bottom sediments distribution of the Ria de Aveiro lagoon bed has a cohesive behaviour. Following Torfs (Torfs, 1995;Mitchener & Torfs, 1996) the cohesiveness behaviour of a sediment bed depends depend on the ratio of non-cohesive and cohesive particles. Above a critical mud content of 4%, and a critical clay (Kaolinite) content of 3%, as the ripples and dunes are increasingly suppressed and the bed behaved cohesively.…”

mentioning

confidence: 99%

On the Influence of the Nearbed Sediments in the Oxygen Budget of a Lagunar System: The Ria de Aveiro - Portugal

Lopes¹

2011

Sediment Transport - Flow and Morphological Processes

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Effects of estuarine mudflat formation on tidal prism and large‐scale morphology in experiments

Braat

Leuven

Lokhorst

et al. 2018

Earth Surf Processes Landf

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Human interference in estuaries has led to increasing problems of mud, such as hyper‐turbidity with adverse ecological effects and siltation of navigation channels and harbours. To deal with this mud sustainably, it is important to understand its long‐term effects on the morphology and dynamics of estuaries. The aim of this study is to understand how mud affects the morphological evolution of estuaries. We focus on the effects of fluvial mud supply on the spatial distribution of mudflats and on how this influences estuary width, depth, surface area and dynamics over time. Three physical experiments with self‐forming channels and shoals were conducted in a new flume type suitable for tidal experiments: the Metronome. In two of the experiments, we added nutshell grains as mud simulant, which is transported in suspension. Time‐lapse images of every tidal cycle and digital elevation models for every 500 cycles were analysed for the three experiments. Mud settles in distinct locations, forming mudflats on bars and sides of the estuary, where the bed elevation is higher. Two important effects of mud were observed: the first is the slight cohesiveness of mud that causes stability on bars limiting vertical erosion, although the bank erosion rate by migrating channels is unaffected. Secondly, mud fills inactive areas and deposits at higher elevations up to the high‐water level and therefore decreases the tidal prism. These combined effects cause a decrease in dynamics in the estuary and lead to near‐equilibrium planforms that are smaller in volume and especially narrower upstream, with increased bar heights and no channel deepening. This trend is in contrast to channel deepening in rivers by muddier floodplain formation. These results imply large consequences for long‐term morphodynamics in estuaries that become muddier due to management practices, which deteriorate ecological quality of intertidal habitats but may create potential area for marshes. © 2018 The Authors. Earth Surface Processes and Landforms Published by John Wiley & Sons Ltd.

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Settling and consolidation of mud/sand mixtures

Cited by 81 publications

References 4 publications

Monitoring and characterisation of sand-mud sedimentation processes

Monitoring and characterisation of sand-mud sedimentation processes

On the Influence of the Nearbed Sediments in the Oxygen Budget of a Lagunar System: The Ria de Aveiro - Portugal

Effects of estuarine mudflat formation on tidal prism and large‐scale morphology in experiments

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