Propagation of tidal waves up in <scp>Y</scp>angtze <scp>E</scp>stuary during the dry season

Lu, Shan; Tong, Chaofeng; Lee, Dong-Young; Zheng, Jinhai; Shen, Jian; Zhang, Wei; Yan, Yuping

doi:10.1002/2014jc010414

Cited by 56 publications

(37 citation statements)

References 44 publications

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“…Similar to the distribution of maximum shear stress showed in Figure , both the M2 and M4 velocity amplitudes peak at the shoals area (Figure ). Amplitudes and phases of both M2 and M4 are similar to those reported in the modeling study of Lu et al ().…”

Section: Resultssupporting

confidence: 87%

A Positive Feedback Between Sediment Deposition and Tidal Prism May Affect the Morphodynamic Evolution of Tidal Deltas

et al. 2018

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Tidal deltas are fragile systems whose morphology can be easily impacted by variations in water and sediment fluxes caused by natural and human processes. Here we explore the relation between tidal prism and sediment dynamics in tidal deltas using the recent evolution of the Yangtze River estuary, China, as an example. Using the numerical model Delft3D, we examine how changes in delta morphology can trigger variations in tidal signal, suspended and bed load transport, and how these could ultimately cause additional morphological changes. Our results show that a positive feedback between sediment deposition and tidal prism dominates the morphodynamic evolution of the delta. Accretion of the shoals in the delta front increases the dissipation of tides and decreases the tidal prism leading to weaker tidal flows. This reduction in tidal currents lowers the sediment flushing capacity of the system, promoting deposition on the shoals and tidal dissipation. This positive feedback potentially traps more sediment in the delta topset and possibly offsets the decrease in sediment load triggered by the construction of upstream dams, often present in tidal deltas.

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Section: Resultssupporting

confidence: 87%

A Positive Feedback Between Sediment Deposition and Tidal Prism May Affect the Morphodynamic Evolution of Tidal Deltas

et al. 2018

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“…Figure shows how the M 2 tide propagates into the branches in Model 2 and in the realistic model (Lu et al, ; Zhang et al, ). The two models feature similar tidal behavior.…”

Section: Model Setup and Verificationmentioning

confidence: 99%

Subtidal Flow Reversal Associated With Sediment Accretion in a Delta Channel

Zhang

Feng

Zhu

et al. 2019

Water Resources Research

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In branching delta channel networks, tides intrude into parallel river outlets causing complex tidal behavior. The tidal motion can impact the division of river discharge over distributary channels. Under some circumstances, the discharge averaged over a tidal cycle may even reverse, drawing ocean water intox the delta, such as observed in the Yangtze Delta, the Fly Delta and the Colorado Delta. Here, we study the flow reversal associated with sediment accumulation of a distributary channel in terms of tidal propagation and subtidal discharge dynamics, by focusing on the Yangtze Delta. The Yangtze Delta channel configuration represents a deep and wide main channel and a smaller side channel that has rapidly accreted over the past decades. A new mechanism is presented, which results in seawater transport across the shallow side channel, posing a risk to freshwater availability. The shallowest section in the side channel nearly acts as a tidal divide. In this section, the tide has the character of a standing wave, which implies that Stokes transport converges from opposite sides of the channel. This leads to significant variation of the total water storage in the side channel and subtidal water levels in the side channel being elevated above that in the main channel. The bulge of water that is stored during spring tide leaves the side channel toward neap tide, explaining reversal of the tide-averaged discharge and seawater intrusion when the river discharge is low.

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“…Tides in the Yangtze River Estuary are semidiurnal with the average tidal range of 2.76 m and the maximum of 4.62 m (Lu et al 2015) or 5.0 m (Chen et al 1998).…”

Section: Tidal River Dynamicsmentioning

confidence: 99%

The hyperpycnite problem

Shanmugam

2018

J. Palaeogeogr.

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Sedimentologic, oceanographic, and hydraulic engineering publications on hyperpycnal flows claim that (1) river flows transform into turbidity currents at plunge points near the shoreline, (2) hyperpycnal flows have the power to erode the seafloor and cause submarine canyons, and, (3) hyperpycnal flows are efficient in transporting sand across the shelf and can deliver sediments into the deep sea for developing submarine fans. Importantly, these claims do have economic implications for the petroleum industry for predicting sandy reservoirs in deep-water petroleum exploration. However, these claims are based strictly on experimental or theoretical basis, without the supporting empirical data from modern depositional systems. Therefore, the primary purpose of this article is to rigorously evaluate the merits of these claims. A global evaluation of density plumes, based on 26 case studies (e.g., Yellow River, Yangtze River, Copper River, Hugli River (Ganges), Guadalquivir River, Río de la Plata Estuary, Zambezi River, among others), suggests a complex variability in nature. Real-world examples show that density plumes (1) occur in six different environments (i.e., marine, lacustrine, estuarine, lagoon, bay, and reef); (2) are composed of six different compositional materials (e.g., siliciclastic, calciclastic, planktonic, etc.); (3) derive material from 11 different sources (e.g., river flood, tidal estuary, subglacial, etc.); (4) are subjected to 15 different external controls (e.g., tidal shear fronts, ocean currents, cyclones, tsunamis, etc.); and, (5) exhibit 24 configurations (e.g., lobate, coalescing, linear, swirly, U-Turn, anastomosing, etc.). Major problem areas are: (1) There are at least 16 types of hyperpycnal flows (e.g., density flow, underflow, high-density hyperpycnal plume, high-turbid mass flow, tide-modulated hyperpycnal flow, cyclone-induced hyperpycnal turbidity current, multi-layer hyperpycnal flows, etc.), without an underpinning principle of fluid dynamics. (2) The basic tenet that river currents transform into turbidity currents at plunge points near the shoreline is based on an experiment that used fresh tap water as a standing body. In attempting to understand all density plumes, such an experimental result is inapplicable to marine waters (sea or ocean) with a higher density due to salt content. (3) Published velocity measurements from the Yellow River mouth, a classic area, are of tidal currents, not of hyperpycnal flows. Importantly, the presence of tidal shear front at the Yellow River mouth limits seaward transport of sediments. (4) Despite its popularity, the hyperpycnite facies model has not been validated by laboratory experiments or by real-world empirical field data from modern settings. (5) The presence of an erosional surface within a single hyperpycnite depositional unit is antithetical to the basic principles of stratigraphy. (6) The hypothetical model of "extrabasinal turbidites", deposited by river-flood triggered hyperpycnal flows, is untenable. This is because high-densit...

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Propagation of tidal waves up in Yangtze Estuary during the dry season

Cited by 56 publications

References 44 publications

A Positive Feedback Between Sediment Deposition and Tidal Prism May Affect the Morphodynamic Evolution of Tidal Deltas

A Positive Feedback Between Sediment Deposition and Tidal Prism May Affect the Morphodynamic Evolution of Tidal Deltas

Subtidal Flow Reversal Associated With Sediment Accretion in a Delta Channel

The hyperpycnite problem

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