Numerical Simulations of Meanders Migrating Laterally as They Incise Into Bedrock

Inoue, Takuya; Mishra, Jagriti; Parker, Gary

doi:10.1029/2020jf005645

Cited by 15 publications

(14 citation statements)

References 60 publications

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“…For bedrock rivers evolving over millennial timescales, the inclusion of a lateral erosion law into long‐term landscape evolution models (e.g., cellular models) is a challenge (Lague, 2014). Several models have been proposed at either river‐scale (Hancock & Anderson, 2002; Inoue et al., 2021; Malatesta et al., 2017; Murray & Paola, 1994), or catchment‐scale (Coulthard et al., 2013). On the basis of empirical data, Howard and Knutson (1984) related bank retreat rate to the local and upstream‐integrated curvature.…”

Section: A Hierarchy Of Models For Bank Retreatmentioning

confidence: 99%

A Review on Bank Retreat: Mechanisms, Observations, and Modeling

Zhao

Coco

Gong

et al. 2022

Reviews of Geophysics

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Bank retreat plays a fundamental role in fluvial and estuarine dynamics. It affects the cross‐sectional evolution of channels, provides a source of sediment, and modulates the diversity of habitats. Understanding and predicting the geomorphological response of fluvial/tidal channels to external driving forces underpins the robust management of water courses and the protection of wetlands. Here, we review bank retreat with respect to mechanisms, observations, and modeling, covering both rivers and (previously neglected) tidal channels. Our review encompasses both experimental and in situ observations of failure mechanisms and bank retreat rates, modeling approaches and numerical methods to simulate bank erosion. We identify that external forces, despite their distinct characteristics, may have similar effects on bank stability in both river and tidal channels, leading to the same failure mode. We review existing data and empirical functions for bank retreat rate across a range of spatial and temporal scales, and highlight the necessity to account for both hydraulic and geotechnical controls. Based on time scale considerations, we propose a new hierarchy of modeling styles that accounts for bank retreat, leading to clear recommendations for enhancing existing modeling approaches. Finally, we discuss systematically the feedbacks between bank retreat and morphodynamics, and suggest that to move this agenda forward will require a better understanding of multifactor‐driven bank retreat across a range of temporal scales, with particular attention to the differences (and similarities) between riverine and estuarine environments, and the role of feedbacks exerted by the collapsed bank soil.

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Section: A Hierarchy Of Models For Bank Retreatmentioning

confidence: 99%

A Review on Bank Retreat: Mechanisms, Observations, and Modeling

Zhao

Coco

Gong

et al. 2022

Reviews of Geophysics

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“…The unevenness of the riverbed (Li et al., 2021) and the flow meandering via bar formation (Mishra et al., 2018) cause sediments to collide with the sidewalls, leading to lateral erosion of bedrock channel (Inoue et al., 2021). Although the increase in channel width due to lateral erosion may reduce the effect of sidewall resistance, lateral erosion is not considered in the model proposed in this study due to the complexity of modeling, for example, how to handle overhanging walls and how to move the inner channel sidewall grid in the horizontal plane.…”

Section: Numerical Modelmentioning

confidence: 99%

Numerical Study of the Interaction Between Wet‐Dry Weathering and Bedload Induced Abrasion

Sumner

Mishra

Inoue

et al. 2022

Water Resources Research

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Erosion and weathering have always been considered as key factors regulating landscape morphodynamics. In this study, we implemented a numerical model that incorporates the effect of abrasion by saltation as well as the effect of slaking by wet‐dry weathering. Our numerical results indicate abrasion and weathering acting together on bedrock beds, that is, abrasion leads to a deep inner channel, and weathering leads to flat benches on the channel margins. We also inquired how changes in the water discharge, alluvial cover, bedrock strength and weathering depth define the abrasion and weathering rates. We found that changes in water discharge can control the weathering rate and depth and thereby the channel shape. Alluvial cover acts as tools or cover to determine the abrasion rates. Our results show that bedrock strength minimally changes the channel cross‐section while weathering depth controls the valley depth. Since weathering and abrasion occur at different heights in the channel cross‐section, there is little opportunity for weathered bedrock to be abraded. However, weathering and abrasion interact indirectly through changes in channel morphology. The internal channel incision lowers the elevation of wet‐dry weathering zone, and the formation of the bedrock bench reduces the bedload transport rate, which drives saltation‐abrasion.

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“…Mixed bedrock‐alluvial channels are characterized by occasional or continuous exposures of nonalluviated bedrock, which can range in form from longitudinal stripes (e.g., Inoue & Nelson, 2020), free bars (e.g., Chatanantavet & Parker, 2008; Milan et al., 2020), to point bars at meander bends (e.g., Fernandez et al., 2019; Inoue et al., 2021; Mishra et al., 2018; P. A. Nelson et al., 2014; Nittrouer et al., 2011). These channels are often considered to have sediment supply that is less than their sediment transport capacity (e.g., Whipple et al., 2013), although adjustments in partial cover may reflect recent short‐term adjustments toward grade rather than long‐term imbalances between sediment supply and capacity (Turowski, 2020).…”

Section: Introductionmentioning

confidence: 99%

Patterns of Alluviation in Mixed Bedrock‐Alluvial Channels: 2. Controls on the Formation of Alluvial Patches

Cho,

Nelson

2024

JGR Earth Surface

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Understanding the development and spatial distribution of alluvial patches in mixed bedrock‐alluvial rivers is necessary to predict the mechanisms of the interactions between sediment transport, alluvial cover, and bedrock erosion. This study aims to analyze bedrock alluviation patterns using a 2D morphodynamic model, and to use the model results to better understand the mechanisms responsible for alluvial patterns observed experimentally. A series of simulations are conducted to explore how alluvial patterns in mixed bedrock‐alluvial channels form and evolve for different channel slopes and antecedent sediment layer thicknesses. In initially bare bedrock low‐slope channels, sediment cover increases with increasing sediment supply because areas of Froude‐subcritical flow enable sediment deposition, while in steep‐slope channels the flow remains fully supercritical and the model predicts so‐called runaway alluviation. For channels initially covered with sediment, the model predicts a slope‐dependent sediment supply threshold above which sediment cover increases with increasing sediment supply, and below which the bedrock becomes fully exposed. For a given sediment supply, the fraction of bedrock exposure and average alluvial thickness converge toward the equilibrium value regardless of the initial cover thickness as long as it exceeds a minimum threshold. Steep channels are able to maintain a continuous strip of sediment under sub‐capacity sediment supply conditions by achieving a balance between increased form drag as bedforms develop and reduced surface roughness as the portion of alluvial cover decreases. In lower‐slope channels, alluvial patches are distributed sporadically in regions of the subcritical flow.

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Numerical Simulations of Meanders Migrating Laterally as They Incise Into Bedrock

Cited by 15 publications

References 60 publications

A Review on Bank Retreat: Mechanisms, Observations, and Modeling

A Review on Bank Retreat: Mechanisms, Observations, and Modeling

Numerical Study of the Interaction Between Wet‐Dry Weathering and Bedload Induced Abrasion

Patterns of Alluviation in Mixed Bedrock‐Alluvial Channels: 2. Controls on the Formation of Alluvial Patches

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