Cyclic steps: A phenomenon of supercritical shallow flow from the high mountains to the bottom of the ocean

Kostic, Svetlana; Sequeiros, Octavio E.; Spinewine, Benoît; Parker, Gary

doi:10.1016/j.jher.2009.10.002

Cited by 93 publications

(84 citation statements)

References 16 publications

(16 reference statements)

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“…Strong evidence has been offered that many of the sediment waves formed by turbidity currents are cyclic steps Fildani et al, 2006;Spinewine et al, 2009;Kostic, 2011;Cartigny et al, 2011), i.e., trains of cyclic bed undulations forming beneath internal hydraulic jumps in an overriding turbidity current that encounters a slope break (see the summary on cyclic steps in subaerial and submarine environments in Kostic et al, 2010). Previous studies on cyclic steps have addressed only necessary, but not suffi cient, hydrodynamic conditions for their self-initiation (Kostic andParker, 2006, Kostic, 2011), and offered several fi eld-scale examples of self-initiated net-depo sitional coarse-grained and net-erosional fi ne-grained cyclic steps (e.g., Fildani et al, 2006).…”

Section: Wave Formation and Evolutionmentioning

confidence: 99%

Upper flow regime bedforms on levees and continental slopes: Turbidity current flow dynamics in response to fine-grained sediment waves

Kostic

2014

Geosphere

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Section: Wave Formation and Evolutionmentioning

confidence: 99%

Upper flow regime bedforms on levees and continental slopes: Turbidity current flow dynamics in response to fine-grained sediment waves

Kostic

2014

Geosphere

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“…Steppool sequences (Chin 1999, Curran 2007, Lenzi 2001, Weichert, et al, 2008, Whittaker and Jaeggi, 1982 and cyclic steps , Kostic et al 2010 are extreme forms of antidunes, the growth of which has caused the flow to cross periodically the transition from subcritical to supercritical regimes.…”

Section: Introductionmentioning

confidence: 99%

Bedforms in a turbulent stream: ripples, chevrons and antidunes

et al. 2011

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The interaction between a turbulent flow and a granular bed via sediment transport produces various bedforms associated with distinct hydrodynamical regimes. In this paper, we compare ripples (downstream-propagating transverse bedforms), chevrons and bars (bedforms inclined with respect to the flow direction) and antidunes (upstream-propagating bedforms), focusing on the mechanisms involved in the early stages of their formation. Performing the linear stability analysis of a flat bed, we study the asymptotic behaviours of the dispersion relation with respect to the physical parameters of the problem. In the subcritical regime (Froude number $\mathscr{F}$ smaller than unity), we show that the same instability produces ripples or chevrons depending on the influence of the free surface. The transition from transverse to inclined bedforms is controlled by the ratio of the saturation length ${L}_{\mathit{sat}} $, which encodes the stabilizing effect of sediment transport, to the flow depth $H$, which determines the hydrodynamical regime. These results suggest that alternate bars form in rivers during flooding events, when suspended load dominates over bedload. In the supercritical regime $\mathscr{F}\gt 1$, the transition from ripples to antidunes is also controlled by the ratio ${L}_{\mathit{sat}} / H$. Antidunes appear around resonant conditions for free surface waves, a situation for which the sediment transport saturation becomes destabilizing. This resonance turns out to be fundamentally different from the inviscid prediction. Their wavelength selected by linear instability mostly scales on the flow depth $H$, which is in agreement with existing experimental data. Our results also predict the emergence, at large Froude numbers, of ‘antichevrons’ or ‘antibars’, i.e. bedforms inclined with respect to the flow and propagating upstream.

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“…Wohl observed trains of purely incisional rhythmic steps in the beds of bedrock streams 9) , which was theoretically elucidated by Parker and Izumi 1) and successfully regenerated in the laboratory by Koyama and Ikeda 10) . Moreover experimental studies 5) and model analysis 11) for bedrock incision have proven that the same fundamental instability of cyclic step formation can be formulated with the theory of bedrock incision as well.…”

Section: I_503mentioning

confidence: 92%

“…"Chute-and-pool" morphology documented by Simons et al 3) and documentation of field observed step-like structures during sand dam construction in Netherlands, by Winterwerp et al 4) disclosed the basic idea about this peculiar bed undulations. This long wave manifestation was christened as "cyclic steps" by Parker 5) with the light of experiments on the formation of alluvial fans.…”

Section: Introductionmentioning

confidence: 98%

Cyclic steps formed by turbidity currents

Dias

Izumi

Yokokawa

2011

J. JSCE

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Levees of channels formed due to turbidity currents on submarine fans are often covered with step like bedforms. Circumstantial evidences emerged with numerical and experimental studies have suggested these sediment waves should probably be cyclic steps. The formation of cyclic steps in sub-aqueous environments through a mathematical perspective is presented in this research. A mathematical model preserving essential physics of the system is solved for one step wave length to obtain a preserved step shape of upstream migrating steps and the behavior of characteristic parameters governing this cyclic step formation phenomenon.

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Cyclic steps: A phenomenon of supercritical shallow flow from the high mountains to the bottom of the ocean

Cited by 93 publications

References 16 publications

Upper flow regime bedforms on levees and continental slopes: Turbidity current flow dynamics in response to fine-grained sediment waves

Upper flow regime bedforms on levees and continental slopes: Turbidity current flow dynamics in response to fine-grained sediment waves

Bedforms in a turbulent stream: ripples, chevrons and antidunes

Cyclic steps formed by turbidity currents

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