The influence of clay on the threshold of movement of fine sandy beds

Panagiotopoulos, Ioannis; Voulgaris, George; Collins, Michael B.

doi:10.1016/s0378-3839(97)00013-6

Cited by 148 publications

(88 citation statements)

References 21 publications

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“…By combining this τ e,mud value with the minimum erodibility parameter E 0,mud recommended by e.g., Winterwerp [54], i.e., 10 −5 kg·m −2 ·s −1 , the application of the mud erosion law from the model (Section 3.3) led to good agreement between modelled erosion fluxes and those obtained in erodimetry experiments for comparable applied shear stresses ( Figure 5). Such a lower critical stress for erosion when the mixture is muddier is opposite to trends most often published, characterized by an increase of the resistance to erosion when mud is added to sand (e.g., [6,7,[14][15][16][17]). Other simulations were performed with higher τ e,mud values, 0.15, 0.2, and 0.4 N·m −2 .…”

Section: Mud Erosion Lawmentioning

confidence: 70%

“…For instance, Mitchener and Torfs [14] proposed a transition between 3% and 15% mud content, and suggested using cohesive-type sediment transport equations above this transition value and sand transport theories below it. Other authors suggested that the transition occurs at much higher mud content, i.e., between 20% and 30% (e.g., [7,15]). More generally, previous investigations emphasized that only 2% to 10% of clay minerals (dry weight) added in a non-cohesive sediment matrix were sufficient to control the soil properties and increase the resistance of the bed to erosion (e.g., [17,24,45,56]).…”

Section: Setting Describing Erosion Of a Sand/mud Mixturementioning

confidence: 99%

“…Panagiotopoulos et al [15] proposed a conceptual model showing the mechanism for the initiation of sediment motion for sand-mud mixtures, based on the forces acting on an individual grain and the associated angle of internal friction. When the mud content increases, clay minerals progressively fill the spaces between the sand particles, which slightly alters the pivoting characteristics and consequently the internal friction angle, and thus a slight change in erosion resistance.…”

Section: Setting Describing Erosion Of a Sand/mud Mixturementioning

confidence: 99%

“…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]. Experiments have provided evidence that the resistance to erosion (i.e., critical shear stress τ e ) increases when mud is added to sand, either because of electrochemical bonds which take effect in binding the sand grains or because a cohesive matrix takes place between and around sand grains (e.g., [6,7,[14][15][16][17]). Literature on erosion rate for mixed sediments is much less abundant, but a significant decrease (several orders of magnitude) in the erosion rate with mud content is most often reported (e.g., [14,17,18]).…”

Section: Introductionmentioning

confidence: 99%

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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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Section: Mud Erosion Lawmentioning

confidence: 70%

Section: Setting Describing Erosion Of a Sand/mud Mixturementioning

confidence: 99%

Section: Setting Describing Erosion Of a Sand/mud Mixturementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

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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“…However, the effects of these clays at such small quantities may be different than at larger concentrations. Very small quantities of clay material (<11 to 14%) can increase critical shear stress by affecting the bed roughness or internal friction angles (Panagiotopoulos et al 1997, Dong 2007. As the percent of fine material increases (>11-14% clay), fine sediment separates all the sand particles, greatly increasing the critical shear stress due to cohesion of the fine particles (Panagiotopoulos et al 1997).…”

Section: Site Differencesmentioning

confidence: 99%

Physical and Biological Controls on Sediment and Nutrient Fluxes in a Temperate Lagoon

Lawson¹

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The lack of riverine inflow and shallow depths in coastal lagoons make the fluxes of nutrients and sediment across the sediment-water interface important controls on primary productivity in these systems. However, the physical-biological coupling that controls these fluxes is not fully understood. Experiments using a Gust microcosm were conducted on samples from Hog Island Bay, a shallow lagoon on the Delmarva Peninsula to determine the physical and biological controls on sediment and nutrient fluxes. Two of the dominant benthic primary producers, seagrass and macroalgae, have traditionally been considered sediment stabilizers. However, at low densities, these primary producers can increase sediment suspension by as much as 97% through flow diversion around isolated shoots or abrasion of the bed by saltating macroalgae. This increased sediment suspension during forcing events may make developing seagrass beds particularly susceptible to light limitation. These primary producers also affect erodibility of the sediment bed, with increased measured erodibility in the summer months attributed to trapping of fine material by dense macroalgal mats, as well as bioturbation by benthic fauna. While these benthic primary producers affect the physical process of sediment suspension, their growth and productivity may be affected by the interaction of physical forcing and nutrient flux. During forcing events, two mechanisms, desorption and porewater advection balanced by biological uptake, create ammonium fluxes an order of magnitude greater than those measured under low-flow conditions. However, these fluxes are likely not sustained and decrease quickly (on the order of hours). This pulsed increase in nutrient availability may create a competitive advantage for fast-growing ii species capable of surge uptake of nutrients, such as macroalgae and phytoplankton. In this sense, the timing of nutrient fluxes may be as important as the cumulative magnitude.iii

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A vector-based method for bank-material tracking in coupled models of meandering and landscape evolution

Limaye

Lamb

2013

J. Geophys. Res. Earth Surf.

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[1] Sinuous channels commonly migrate laterally and interact with banks of different strengths-an interplay that links geomorphology and life and shapes diverse landscapes from the seafloor to planetary surfaces. To investigate feedbacks between meandering rivers and landscapes over geomorphic timescales, numerical models typically represent bank properties using grids; however, this approach produces results inherently dependent on grid resolution. Herein we assess existing techniques for tracking landscape and bank-strength evolution in numerical models of meandering channels and show that grid-based models implicitly include unintended thresholds for bank migration that can control simulated landscape evolution. Building on stratigraphic modeling techniques, we develop a vector-based method for land surface-and subsurface-material tracking that overcomes the resolution-dependence inherent in grid-based techniques by allowing high-fidelity representation of bank-material properties for curvilinear banks and low channel lateral migration rates. We illustrate four specific applications of the new technique: (1) the effect of resistant mud-rich deposits in abandoned meander cutoff loops on meander belt evolution; (2) the stratigraphic architecture of aggrading, alluvial meandering channels that interact with cohesive-bank and floodplain material; (3) the evolution of an incising, meandering river with mixed bedrock and alluvial banks within a confined bedrock valley; and (4) the effect of a bank-height dependent lateral-erosion rate for a meandering river in an aggrading floodplain. In all cases the vector-based approach overcomes numerical artifacts with the grid-based model. Because of its geometric flexibility, the vector-based material tracking approach provides new opportunities for exploring the coevolution of meandering rivers and surrounding landscapes over geologic timescales.Citation: Limaye, A. B. S., and M. P. Lamb (2013), A vector-based method for bank-material tracking in coupled models of meandering and landscape evolution,

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The influence of clay on the threshold of movement of fine sandy beds

Cited by 148 publications

References 21 publications

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

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

Physical and Biological Controls on Sediment and Nutrient Fluxes in a Temperate Lagoon

A vector-based method for bank-material tracking in coupled models of meandering and landscape evolution

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