An experimental study on the effects of physical, mechanical, and electrochemical properties of natural cohesive soils on critical shear stress and erosion rate

Kimiaghalam, Navid; Clark, Shawn P.; Ahmari, Habib

doi:10.1016/j.ijsrc.2015.01.001

Cited by 64 publications

(25 citation statements)

References 25 publications

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“…This value permits a reasonable amount of deposition in the domain. The critical shear stress for erosion is set to 2 N/m 2 , which also falls within the reasonable range for erosive shear stresses for fine‐grained, cohesive sediment and does not allow for excessive channel erosion during elevated discharge events (Clark & Wynn, ; Kimiaghalam et al, ). Based on historical satellite imagery, we know that the Muscatatuck River channel is relatively stable and any shear stress values for erosion that allow for rapid changes to the channel planform are not representative of the natural system.…”

Section: Methodsmentioning

confidence: 99%

Connecting Fluvial Levee Deposition to Flood‐Basin Hydrology

2019

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Levees are commonly found along every kind of river system, yet there are no widely accepted models for where along the channel they form and what controls their shape. In this study, we investigated whether levee growth is driven by sediment transfer from the channel adjacent to the levee or by inundation dynamics in the flood basin. To test these ideas, we conducted empirical analyses and numerical modeling of levees on the fine-grained, meandering Muscatatuck River, IN. Using LiDAR data, we found no statistical relationship between the levee and the adjacent channel planform, which suggests levees are not genetically related to their adjacent channel. On the contrary, modeling experiments of a simplified Muscatatuck River show that levee initiation can be genetically related to the adjacent channel because bed shear stress on the floodplain is low where channel curvature is high. But after levees initiate, the genetic connection to the adjacent channel is obscured because levee shape is modified by inundation dynamics. For instance, tall mature levees are not inundated regularly and instead obstruct floodplain flow, creating flow shadows on the downstream side. Sediment is preferentially deposited in the flow shadow, which moves the location of maximum deposition from the levee crest to the toe. This causes levees to prograde down-valley, which reshapes the levee and genetically disconnects it from the channel. We propose that this morphodynamic mechanism of levee growth is characteristic of fine-grained rivers in narrow floodplains where flood basins can act as conveyance channels that transport sediment down-valley before deposition. Key Points:• Empirical analyses of LiDAR data on the Muscatatuck River, Indiana, USA, show that levee size and shape are unrelated to channel planform • Numerical modeling reveals that levee initiation is related to the channel planform but subsequent growth is influenced by inundation dynamics in the flood basin • On tall levees, the levee toe grows faster than the levee crest because it is inundated more frequently, and this causes levees to prograde down-valley over time

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Section: Methodsmentioning

confidence: 99%

Connecting Fluvial Levee Deposition to Flood‐Basin Hydrology

2019

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“…The parameters of such an erosion law involve bed characteristics, which may concern electrochemical forces, mineral composition, and organic matter content [2], or pore water characteristics [3]. They also depend on the consolidation state [4], and may be altered by biota effects [5].…”

Section: Introductionmentioning

confidence: 99%

“…They also depend on the consolidation state [4], and may be altered by biota effects [5]. Bulk density has often been proposed as a proxy for characterizing the bed, but the plasticity index has also been suggested [6], as well as the undrained cohesion and the sodium adsorption ratio [3].…”

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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“…We measured the subaqueous topography down to 2.5 m below the minimum stage and took seven surface samples along reach B (Figure 2) on January 2017. Following the studies of Kimiaghalam et al (2016), we used cohesion (C) as an indication of the material erodibility to make a hierarchy of erosion resistance between different areas. Then, we estimated critical shear stresses for entrainment (τ c ) through the linear relation…”

Section: Factors Affecting Bank Resistancementioning

confidence: 99%

Distinct patterns of bank erosion in a navigable regulated river

Duró

Crosato

Kleinhans

et al. 2019

Earth Surf Processes Landf

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Distinct bankline patterns appeared after the removal of protection works along a navigable reach of the Meuse River. A series of oblique embayments now dominate the riverine landscape after ten years of bank erosion, but their location and asymmetry cannot be explained yet. This work analyses and integrates field measurements of flow, ship waves, bank composition, bed topography and historical maps to explain the observed patterns along two reaches of the river. An extraordinary low-water-level event generated by a ship accident provided the unique opportunity to also analyse the subaqueous bank topography.The results indicate that the formation of oblique embayments arises from the combination of floodplain heterogeneity, structured by scroll-bar deposits, and the regulation of water levels, resulting in ship-wave attack at a narrow range of bank elevation for 70% of the time. Substrate erodibility acts on the effectiveness of trees to slow down local bank erosion rates, which is possibly enhanced by a positive feedback between woody roots and cohesive soil. The strong regulation of water levels and the waves generated by the intense ship traffic produce an increasingly long mildly-sloping terrace at the bank toe and progressively dominate the bank erosion process. This study demonstrates the important role of floodplain and scroll bar formation in shaping later bank erosion, which has implications for predictive numerical models, restoration strategies, and understanding the role of vegetation in bank erosion processes.

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An experimental study on the effects of physical, mechanical, and electrochemical properties of natural cohesive soils on critical shear stress and erosion rate

Cited by 64 publications

References 25 publications

Connecting Fluvial Levee Deposition to Flood‐Basin Hydrology

Connecting Fluvial Levee Deposition to Flood‐Basin Hydrology

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

Distinct patterns of bank erosion in a navigable regulated river

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