Morphodynamics and sedimentary facies in a tidal‐fluvial transition with tidal bores (the middle Qiantang Estuary, China)

Fan, Daidu; Tu, Junbiao; Shang, Shuai; Zhang, Yue

doi:10.1002/9781119218395.ch5

Cited by 4 publications

(7 citation statements)

References 16 publications

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“…erosional or passively draping) might initially appear inconsistent with this high-energy interpretation of their formation. Most models for tidal bores talk about intense resuspension of sediment from the bed as the bore passes, which should generate a prominent erosional surface (Chanson, 2005;Docherty & Chanson, 2012), such as has been documented for inferred, ancient tidal-bore deposits (Martinius & Gowland, 2011;Fielding & Joeckel, 2015), and which has been incorporated in proposed facies models for tidal-bore deposits (Fan et al, 2012(Fan et al, , 2014(Fan et al, , 2016Tessier et al, 2017). There are prominent erosional surfaces locally within the CB-SR peels (for example, Fig.…”

Section: Structureless Layersmentioning

confidence: 99%

“…The data on tidal-bore deposits from a single depositional system such as are reported here, despite the better areal coverage than any previous study, do not capture the full spectrum of possible expressions of tidal bores. In the CB-SR system, the tidal-bore Froude number is sufficiently high (Fr tb = 2 to 3) to generate breaking bores commonly, but much larger and more energetic bores are present in other systems, including notably Mont Saint Michel Bay (Tessier & Terwindt, 1994;Furgerot et al, 2013Furgerot et al, , 2016aFurgerot, 2014), Turnagain Arm, Alaska (Greb & Archer, 2007), the Qiantang Estuary, China (Fan et al, 2012(Fan et al, , 2014(Fan et al, , 2016 and the Sittaung River estuary, Myanmar (Choi et al, 2020). In the case of the Qiantang Estuary, which is reputed to have the largest tidal bores on Earth at the present time, the structureless sands deposited by tidal bores are commonly >10 cm thick, and appear to average between 5 cm and 10 cm thick (Fan et al, 2014, figs 3 and 4).…”

Section: Variability Of Tidal-bore Deposits: Is a Single Universal Facies Model Possible?mentioning

confidence: 99%

“…Soft‐sediment deformation (SSD) structures are commonly associated with tidal bores and their deposits (Tessier & Terwindt, 1994; Greb & Archer, 2007; Fan et␣al ., 2012, 2014, 2016; Furgerot, 2014; Furgerot et␣al ., 2016a; Tessier et␣al ., 2017). Such structures are present in the cores examined here (for example, Fig.…”

Section: Origin Of Sedimentary Structuresmentioning

confidence: 99%

“…The small size of the tidal bore also restricts its influence to the lowermost part of the tidal frame (Fig. 11), to areas below the level where heterolithic tidal rhythmites occur (Dalrymple et␣al ., 1991), thereby limiting its potential to generate SSD structures relative to areas with larger tidal bores and smaller tidal ranges (for example, Mont Saint Michel Bay – Tessier & Terwindt, 1994; Furgerot, 2014; Furgerot et␣al ., 2016a; Tessier et␣al ., 2017; Qiantang River Estuary – Fan et␣al ., 2012, 2014, 2016; Turnagain Arm, Alaska – Greb & Archer, 2007).…”

Section: Origin Of Sedimentary Structuresmentioning

confidence: 99%

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Sedimentation on high‐energy sand flats in the Bay of Fundy: The record of tidal‐bore activity and deposition from high‐concentration suspensions of sand

Dalrymple

2021

Sedimentology

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The Cobequid Bay -Salmon River estuary, Bay of Fundy, does not possess particularly large tidal bores (maximum ca 30 cm). Nevertheless, detailed logging of 13 peels made from cores spread throughout the entire area influenced by tidal bores indicates that inferred tidal-bore deposits comprise approximately 15% of the deposits in the upper-flow-regime sand flats in the inner part of the estuary, averaging more than 10 tidal-bore layers per metre of core. A landward increase in tidal-bore height is accompanied by an increase in the number and thickness of the tidal-bore layers. The deposit of a single tidal bore begins with structureless sand (from <1 cm to >10 cm thick) that can be gradationally overlain by sand with indistinct parallel lamination, which in turn passes upward into the well-defined parallel lamination that is the dominant sedimentary structure in these sand-flat deposits. The bases of the structureless layers range from prominently erosional to passively draping over the ripples formed during the preceding ebb tide. The structureless and indistinctly laminated layers are interpreted to be the deposit of boregenerated hyperconcentrated suspensions of sand that have similarities with turbidity currents in which near-bed turbulence is extinguished or damped. The tidal-bore Froude number (Fr tb ), which determines the nature of the tidal bore, together with the height of the tidal bore, influences the amount of sand in suspension, and presumably also controls the nature of the deposits. Tidal bores with high Froude numbers (Fr tb = 2 to 3) that are breaking create deposits that are analogous to the deposits of high-concentration turbidity currents; most bore deposits documented to date from other ancient and modern settings are of this high-energy type. Tidal bores that are closer to the lower limit of bore occurrence (Fr tb = 1) generate deposits that will be difficult to distinguish from the background sedimentation.Keywords Bay of Fundy, high-concentration turbidity currents, parallel lamination, tidal-bore deposits, tidal bores, tide-dominated estuary, upper flow regime sedimentation. Thus, their deposits might be common in tidedominated estuaries and deltas, wherever the incoming tidal wave becomes strongly asymmetrical, and especially in areas with a flood-tide dominance and at times with low river flow.

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Section: Structureless Layersmentioning

confidence: 99%

Section: Variability Of Tidal-bore Deposits: Is a Single Universal Facies Model Possible?mentioning

confidence: 99%

Section: Origin Of Sedimentary Structuresmentioning

confidence: 99%

Section: Origin Of Sedimentary Structuresmentioning

confidence: 99%

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Sedimentation on high‐energy sand flats in the Bay of Fundy: The record of tidal‐bore activity and deposition from high‐concentration suspensions of sand

Dalrymple

2021

Sedimentology

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“…Breaking bores like those present in the Qiantang Estuary are extremely energetic and produce violent sediment resuspension events that can last in excess of 10 min, resulting in large sediment transport rates and significant channel topographical changes [ Dai and Zhou , ; Chen et al ., ; Han et al ., ; Pan and Huang , ; Chanson , ; Fan et al ., ]. The mighty Qiantang bore was observed to produce remarkable atmosphere noise [ Chanson , ], and simulations showed to be characterized by high turbulent flow with large scale vortices, kinetic energy dissipation, and air entrainment [ Leng and Chanson , ].…”

Section: Introductionmentioning

confidence: 99%

Flow and turbulence structure in a hypertidal estuary with the world's biggest tidal bore

Fan

2017

JGR Oceans

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Turbulent and flow structure associated with breaking tidal bores are deliberately investigated on the basis of field measurements. High‐resolution velocity and hydrographic data are collected in the middle Qiantang Estuary by a vertical array of acoustic Doppler velocimeters and optical backscatter sensors, collaborated with a bottom‐mounted acoustic Doppler current profiler. Besides obvious variations in diurnal and spring‐neap tidal cycles, the estuarine dynamics is featured by extreme asymmetry in flood and ebb tides. The flood tide is abnormally accelerated to generate tidal bores at the first 10 min or more, with breaking or undular configurations at the front. The occurrence of peak flow velocity, turbulent kinetic energy (TKE), and TKE dissipation rate (ε) is definitely associated with breaking bores, with their values several times to 2 orders of magnitude larger than the corresponding secondary peak values during the maximum ebb flows. Flow and turbulence dynamics are significantly affected by the tidal‐bore Froude number. A sandwich ε structure is clear exhibited with the maximum value at the surface, secondary maximum near the bed, and the minimum at the intermediate. Dual TKE sources are indicated by an approximate local balance between shear production and dissipation near the bottom, and a top‐down TKE dissipation using the modified Froude scaling in the vertical water column. The highly elevated dissipation by breaking bores is comparable to that by intense breaking waves in the surf zone, and the former potentially penetrates the entire water column to produce extreme sediment‐resuspension events in combination with intense bottom shear stress.

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Distinction and grain-size characteristics of intertidal heterolithic deposits in the middle Qiantang Estuary (East China Sea)

et al. 2015

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Morphodynamics and sedimentary facies in a tidal‐fluvial transition with tidal bores (the middle Qiantang Estuary, China)

Cited by 4 publications

References 16 publications

Sedimentation on high‐energy sand flats in the Bay of Fundy: The record of tidal‐bore activity and deposition from high‐concentration suspensions of sand

Sedimentation on high‐energy sand flats in the Bay of Fundy: The record of tidal‐bore activity and deposition from high‐concentration suspensions of sand

Flow and turbulence structure in a hypertidal estuary with the world's biggest tidal bore

Distinction and grain-size characteristics of intertidal heterolithic deposits in the middle Qiantang Estuary (East China Sea)

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