Introduction

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

doi:10.1016/s0070-4571(04)80002-5

Cited by 26 publications

(17 citation statements)

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“…Fluid mud can reach densities of up to ca 1250 kg m −3 (e.g. Winterwerp & van Kesteren, ; Mehta, ), which is equivalent to a volumetric kaolinite concentration of ca 15·5% and a yield stress of 4·8 N m −2 (Eq. ; Wan, ).…”

Section: Discussionmentioning

confidence: 99%

“…Widespread evidence exists for the presence of fluid mud, formed by rapid sedimentation of mud or liquefaction of mud deposits, in natural environments (e.g. Whitehouse et al ., ; Winterwerp & van Kesteren, ). Fluid mud has been found mostly in harbours and navigation channels (e.g.…”

Section: Discussionmentioning

confidence: 99%

“…Deposition may take place en masse in clay‐rich flows, if the clay forms a gel, i.e. a pervasive network of clay particle bonds (Winterwerp & van Kesteren, ; Baas et al ., , ). The textural and structural properties of sediment gravity flow deposits are controlled by spatio‐temporal changes in flow dynamics and sediment properties.…”

Section: Introductionmentioning

confidence: 99%

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Thresholds of intrabed flow and other interactions of turbidity currents with soft muddy substrates

et al. 2016

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Controlled laboratory experiments reveal that the lower part of turbidity currents has the ability to enter fluid mud substrates, if the bed shear stress is higher than the yield stress of the fluid mud and the density of the turbidity current is higher than the density of the substrate. Upon entering the sub-strate, the turbidity current either induces mixing between flow-derived sediment and substrate sediment, or it forms a stable horizontal flow front inside the fluid mud. Such 'intrabed' flow is surrounded by plastically deformed mud; otherwise it resembles the front of a 'bottom-hugging' turbidity current. The 'suprabed' portion of the turbidity current, i.e. the upper part of the flow that does not enter the substrate, is typically separated from the intrabed flow by a long horizontal layer of mud which originates from the mud that is swept over the top of the intrabed flow and then incorporated into the flow. The intrabed flow and the mixing mechanism are specific types of interaction between turbidity currents and muddy substrates that are part of a larger group of interactions, which also include bypass, deposition, erosion and soft sediment deformation. A classification scheme for these types of interactions is proposed, based on an excess bed shear stress parameter, which includes the difference in the bed shear stress imposed by the flow and the yield stress of the substrate and an excess density parameter, which relies on the density difference between the flow and the substrate. Based on this classification scheme, as well as on the sedimentological properties of the laboratory deposits, an existing facies model for intrabed turbidites is extended to the other types of interaction involving soft muddy substrates. The physical threshold of flow-substrate mixing versus stable intrabed flow is defined using the gradient Richardson number, and this method is validated successfully with the laboratory data. The gradient Richardson number is also used to verify that stable intrabed flow is possible in natural turbidity currents, and to determine under which conditions intrabed flow is likely to be unstable. It appears that intrabed flow is likely only in natural turbidity currents with flow velocities well below ca 3Á5 m s À1 , although a wider range of flows is capable of entering fluid muds. Below this threshold velocity , intrabed flow is stable only at high-density gradients and low-velocity gradients across the upper boundary of the turbidity current. Finally, the gradient Richardson number is used as a scaling parameter to set the flow velocity limits of a natural turbidity current that formed an inferred intrabed 2002

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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Thresholds of intrabed flow and other interactions of turbidity currents with soft muddy substrates

et al. 2016

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“…Type I erosion occurs in cohesive sediments that are homogeneous in density and thus the critical erosional strength and other erodibility parameters do not change with depth [ Vermeyen , 1995]. On the contrary, in fluvial erosion type II, the erodibility parameters are function of depth and time [ Winterwerp and van Kesteren , 2004].…”

Section: Methodsmentioning

confidence: 99%

Secondary current effects on cohesive river bank erosion

Papanicolaou

Elhakeem

Hilldale

2007

Water Resources Research

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[1] The emphasis of this research was placed on the development of a methodology that allows (1) an adequate representation of the distribution of the near-bank shear stress t s when secondary currents are present and (2) estimation of the critical erosional strength t cr and other sediment erodibility parameters for fluvial erosion. These two factors combine to form the overarching objective of this investigation, which was carried out in Union Flat Creek, a stream with pronounced cross-sectional irregularities located within the loess region of the Palouse basin of Washington State, United States. The study has shown that the presence of the secondary currents increases the magnitude of the depth-averaged sidewall shear stress at least by a factor of 2.0. It was also found that the ratio of the maximum to the depth-averaged sidewall shear stress t s is greater than 5. These findings suggest therefore that use of the t s may be a good approximation of the fluid shear stress magnitude for simple channel geometries but not for natural channels characterized by complex geometries. The measured critical erosional strength (t cr = 4.16 Pa) was comparable with the findings of other laboratory and field studies that also focused on Palouse sediments.

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“…This gives a flocculation time T f % 80 min. From an estimate of k a ¼ 14 m 2 =kg found for mud [25,26], we can evaluate T f ¼ 25 min from Eq. (3) using the shear rate and sediment concentration of our experiments.…”

Section: Time Evolutionmentioning

confidence: 99%