Undersea river patterns

Peakall, Jeff

doi:10.1038/ngeo2509

Cited by 4 publications

(1 citation statement)

References 8 publications

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“…Turbidity currents have previously been compared to rivers. However, our work suggests that this comparison is not always justified, as their basic structure can be fundamentally different 56 , 57 . Rivers are almost always entirely dilute sediment suspensions, with dense bedload layers that are only a few grains thick 58 .…”

Section: Discussionmentioning

confidence: 82%

Powerful turbidity currents driven by dense basal layers

et al. 2018

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Seafloor sediment flows (turbidity currents) are among the volumetrically most important yet least documented sediment transport processes on Earth. A scarcity of direct observations means that basic characteristics, such as whether flows are entirely dilute or driven by a dense basal layer, remain equivocal. Here we present the most detailed direct observations yet from oceanic turbidity currents. These powerful events in Monterey Canyon have frontal speeds of up to 7.2 m s−1, and carry heavy (800 kg) objects at speeds of ≥4 m s−1. We infer they consist of fast and dense near-bed layers, caused by remobilization of the seafloor, overlain by dilute clouds that outrun the dense layer. Seabed remobilization probably results from disturbance and liquefaction of loose-packed canyon-floor sand. Surprisingly, not all flows correlate with major perturbations such as storms, floods or earthquakes. We therefore provide a new view of sediment transport through submarine canyons into the deep-sea.

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Section: Discussionmentioning

confidence: 82%

Powerful turbidity currents driven by dense basal layers

et al. 2018

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Deep-water channels in the lower Congo basin: Evolution of the geomorphology and depositional environment during the Miocene

Liang³

et al. 2020

Marine and Petroleum Geology

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Hydrodynamic instability of meandering channels

Ali

Dey

2017

Physics of Fluids

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In this paper, we explore the hydrodynamic instability of meandering channels driven by the turbulent flow. The governing equations of channel dynamics with suitable boundary conditions are closed with the fluid and granular constitutive relationships. A regular expansion of the fundamental variables is employed to linearize the parent equations by superimposing the perturbations on the basic unperturbed flow. The channel dynamics reveal a resonance phenomenon which occurs when the key variables fall in the vicinity of the distinct critical values. The resonance phenomenon preserves its distinctive signature in different flow regimes which are guided by the characteristic values of the shear Reynolds number. The hydrodynamic analysis indicates that the fluid friction and the volumetric sediment flux play a decisive role to characterize the channel instability in different flow regimes. The growths of azimuthal velocity perturbation in phase with curvature, bed topography perturbation, bend amplification rate, and meander propagation speed in different flow regimes are investigated by varying the meander wavenumber, Shields number, channel aspect ratio, and relative roughness number. The analysis is capable to capture the effects of grain size on azimuthal velocity perturbation, bed topography perturbation, bend amplification rate, and meandering propagation speed over a wide range of shear Reynolds numbers. The variations of resonant wavenumbers in different flow regimes with the Shields number, channel aspect ratio, and relative roughness number are addressed. For a specific flow regime, the upstream and downstream migrations of meandering channels are typically governed by the Shields number, channel aspect ratio, and relative roughness number.

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Undersea river patterns

Cited by 4 publications

References 8 publications

Powerful turbidity currents driven by dense basal layers

Powerful turbidity currents driven by dense basal layers

Deep-water channels in the lower Congo basin: Evolution of the geomorphology and depositional environment during the Miocene

Hydrodynamic instability of meandering channels

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