A conceptual framework for the erosion behaviour of sand–mud mixtures

Ledden, Mathijs van; Kesteren, W.G.M. van; Winterwerp, Johan C.

doi:10.1016/j.csr.2003.09.002

Cited by 248 publications

(169 citation statements)

References 10 publications

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“…In the broadest terms, non-cohesive sediments have mean grain sizes > 63 µm, and cohesive sediments or 'muds' are dominated by fine-grained particles that are < 63 µm. More recently, attention has also been given to erosion of sand-mud mixtures that show complex behaviours strongly influenced by the fraction of mud in the mixture (van Ledden et al 2004, Law et al 2008, Wiberg et al 2013. Little research has focused on the erosion of aquaculture waste solids.…”

Section: Introductionmentioning

confidence: 99%

Erodibility of aquaculture waste from different bottom substrates

Law¹,

Hill²,

Milligan³

et al. 2016

Aquacult. Environ. Interact.

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A laboratory study was carried out to examine the effect of bed sediment texture on the erodibility of salmon aquaculture waste fecal material and salmon feed pellets. Erodibility measurements of this material were made using a Gust microcosm erosion chamber and artificially composed substrates of mud, sand, sand and gravel, sand and cobble, and cobble. Results show that cumulative mass eroded (CME) and erodibility constant (M) can vary by up to an order of magnitude depending on substrate composition, with a mud substrate having higher CME and M values than those of substrates composed of sand, gravel and cobble. Findings from this study suggest that bottom sediment texture plays a major role in aquaculture waste resuspension and subsequent transport and that predictive models of the transport of aquaculture waste should include the erosion dynamics of bottom texture.

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Section: Introductionmentioning

confidence: 99%

Erodibility of aquaculture waste from different bottom substrates

Law¹,

Hill²,

Milligan³

et al. 2016

Aquacult. Environ. Interact.

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“…However, sand and mud interact, which affects the erodibility (see Van Ledden et al, 2004a, for review). Such interactions include dominant mud with some sand that behaves as mud, but for lower mud fractions there is mixed behaviour (Van Ledden et al, 2004a). In particular, mixed sediments increase erosion resistance and decrease erosion rates when the critical shear stress is exceeded compared to pure sand (e.g.…”

Section: Past and Novel Modelling Approaches For Sand-mud Mixturesmentioning

confidence: 99%

“…Mitchener and Torfs, 1996). Over the past decade, mixed sediments have been implemented in several modelling software packages (Van Ledden et al, 2004a;Waeles et al, 2007;Van Kessel et al, 2011;Le Hir et al, 2011;Dam et al, 2016). Long-term morphologic calculations are rare due to computer limitations and lack of spatially and temporally dense data of mud in the bed.…”

Section: Past and Novel Modelling Approaches For Sand-mud Mixturesmentioning

confidence: 99%

“…Below this critical mud content, friction and gravity oppose sediment transport for sand. The critical mud content was chosen to be at a mass fraction of 0.4, which depends on site-specific silt-clay ratios because only the clay fraction is cohesive (McAnally and Mehta, 2001;Van Ledden et al, 2004a). This value is higher than found in flume experiments (0.1-0.2, Torfs 1995;0.05-0.15, Torfs 1996;0.02-0.15, Mitchener and Torfs 1996) but was based on the silt-clay ratios of Dutch tidal systems (0.25-0.5; Van Ledden et al, 2004b).…”

Section: Numerical Model Descriptionmentioning

confidence: 99%

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Effects of mud supply on large-scale estuary morphology and development over centuries to millennia

et al. 2017

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Abstract. Alluvial river estuaries consist largely of sand but are typically flanked by mudflats and salt marshes. The analogy with meandering rivers that are kept narrower than braided rivers by cohesive floodplain formation raises the question of how large-scale estuarine morphology and the late Holocene development of estuaries are affected by cohesive sediment. In this study we combine sand and mud transport processes and study their interaction effects on morphologically modelled estuaries on centennial to millennial timescales. The numerical modelling package Delft3D was applied in 2-DH starting from an idealised convergent estuary. The mixed sediment was modelled with an active layer and storage module with fluxes predicted by the Partheniades-Krone relations for mud and Engelund-Hansen for sand. The model was subjected to a range of idealised boundary conditions of tidal range, river discharge, waves and mud input. The model results show that mud is predominantly stored in mudflats on the side of the estuary. Marine mud supply only influences the mouth of the estuary, whereas fluvial mud is distributed along the whole estuary. Coastal waves stir up mud and remove the tendency to form muddy coastlines and the formation of mudflats in the downstream part of the estuary. Widening continues in estuaries with only sand, while mud supply leads to a narrower constant width and reduced channel and bar dynamics. This self-confinement eventually leads to a dynamic equilibrium in which lateral channel migration and mudflat expansion are balanced on average. However, for higher mud concentrations, higher discharge and low tidal amplitude, the estuary narrows and fills to become a tidal delta.

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“…Assuming a similar erosion law for the whole range of mixed sediments, the problem becomes the assessment of the critical shear stress for erosion on the one hand, and the erosion factor E 0 on the other hand, in the full transition range between cohesive and non-cohesive materials. Following Van Ledden et al [12], the proxy for such a transition could be clay content. An alternative proxy could be mud content (hereafter referred to as f m ), considering that the clay to silt ratio is often uniform in a given study area [13].…”

Section: Introductionmentioning

confidence: 99%

Modelling Fine Sediment Dynamics: Towards a Common Erosion Law for Fine Sand, Mud and Mixtures

Mengual

Hir

Cayocca

et al. 2017

Water

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This study describes the building of a common erosion law for fine sand and mud, mixed or not, in the case of a typical continental shelf environment, the Bay of Biscay shelf, characterized by slightly energetic conditions and a seabed mainly composed of fine sand and muddy sediments. A 3D realistic hydro-sedimentary model was used to assess the influence of the erosion law setting on sediment dynamics (turbidity, seabed evolution). A pure sand erosion law was applied when the mud fraction in the surficial sediment was lower than a first critical value, and a pure mud erosion law above a second critical value. Both sand and mud erosion laws are formulated similarly, with different parameters (erodibility parameter, critical shear stress and power of the excess shear stress). Several transition trends (linear or exponential) describing variations in these erosion-related parameters between the two critical mud fractions were tested. Suspended sediment concentrations obtained from simulations were compared to measurements taken on the Bay of Biscay shelf with an acoustic profiler over the entire water column. On the one hand, results show that defining an abrupt exponential transition improves model results regarding measurements. On the other hand, they underline the need to define a first critical mud fraction of 10 to 20%, corresponding to a critical clay content of 3-6%, below which pure sand erosion should be prescribed. Both conclusions agree with results of experimental studies reported in the literature mentioning a drastic change in erosion mode above a critical clay content of 2-10% in the mixture. Results also provide evidence for the importance of considering advection in this kind of validation with in situ observations, which is likely to considerably influence both water column and seabed sediment dynamics.

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A conceptual framework for the erosion behaviour of sand–mud mixtures

Cited by 248 publications

References 10 publications

Erodibility of aquaculture waste from different bottom substrates

Erodibility of aquaculture waste from different bottom substrates

Effects of mud supply on large-scale estuary morphology and development over centuries to millennia

Modelling Fine Sediment Dynamics: Towards a Common Erosion Law for Fine Sand, Mud and Mixtures

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