Sediment trapping of turbidity maxima in the Changjiang Estuary

Wu, Jiaxue; Liu, James T.; Wang, Xia

doi:10.1016/j.margeo.2012.02.011

Cited by 98 publications

(56 citation statements)

References 49 publications

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“…These data add to both observational and model studies that focus on longitudinal distribution of SSC in the Yangtze Estuary (Wu et al 2012;Jiang et al 2013;Song and Wang 2013;Wan and Zhao 2017). Differences in each crosssection between spring and neap tides mainly concern the intensity of lateral flow.…”

Section: Modelmentioning

confidence: 86%

Longitudinal variation in lateral trapping of fine sediment in tidal estuaries: observations and a 3D exploratory model

Chen

Swart

2018

Ocean Dynamics

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This study investigates the longitudinal variation of lateral entrapment of suspended sediment, as is observed in some tidal estuaries. In particular, field data from the Yangtze Estuary are analysed, which reveal that in one cross-section, two maxima of suspended sediment concentration (SSC) occur close to the south and north sides, while in a cross-section 2 km downestuary, only one SSC maximum on the south side is present. This pattern is found during both spring tide and neap tide, which are characterised by different intensities of turbulence. To understand longitudinal variation in lateral trapping of sediment, results of a new three-dimensional exploratory model are analysed. The hydrodynamic part contains residual flow due to fresh water input, density gradients and Coriolis force and due to channel curvature-induced leakage. Moreover, the model includes a spatially varying eddy viscosity that accounts for variation of intensity of turbulence over the spring-neap cycle. By imposing morphodynamic equilibrium, the two-dimensional distribution of sediment in the domain is obtained analytically by a novel procedure. Results reveal that the occurrence of the SSC maxima near the south side of both crosssections is due to sediment entrapment by lateral density gradients, while the second SSC maximum near the north side of the first cross-section is by sediment transport due to curvature-induced leakage. Coriolis deflection of longitudinal flow also contributes the trapping of sediment near the north side. This mechanism is important in the upper estuary, where the flow due to lateral density gradients is weak.

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Section: Modelmentioning

confidence: 86%

Longitudinal variation in lateral trapping of fine sediment in tidal estuaries: observations and a 3D exploratory model

Chen

Swart

2018

Ocean Dynamics

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“…The dramatic difference in the sediment concentration in the TMZ between the neap and spring tides was due to greater resuspension during spring tides. Because this is the main dynamic mechanism for the formation of the TMZ in the Yangtze River Estuary (Li and Zhang 1998;Shi et al 2006;Wu et al 2012), the spring tides would have stronger effects on the TMZ than the neap tides. Figure 6 shows that the sediment concentration in the TMZ during spring tides (587.23 mg/L) was much higher than that during neap tides (300.25 mg/L).…”

Section: Discussionmentioning

confidence: 99%

“…6 Water discharge at Datong Station during the pre-TGD and post-TGD period Fig. 7 Area of the Yangtze River Estuary TMZ during the neap (left) and spring tides (right) in February, 2009February, et al 2012, and the stratification resulted from the relative contributions of fresh water and tidal current determines the amount of resuspended sediment and the area of the TMZ (Shi 2004;Wu et al 2012;Yang et al 2014). This means that the TMZ area would decrease when upstream runoff increases due to the enhanced stratification, which would inhibit sediment resuspension, and at the same time its dilution effect.…”

Section: Discussionmentioning

confidence: 99%

“…Jiang et al (2013) analyzed the variation of the TMZ in the Yangtze River Estuary under declined sediment discharge by comparing satellite images in different periods. Wu et al (2012) investigated the TMZ behavior and its structure based on the observation in the 2008 flood and dry seasons in the lower reaches of the Yangtze River Estuary and found the magnitude and extent of the TMZ are strongly seasonal under the influence of distinct sediment processes. Shi et al (2010) employed a two-dimensional horizontal numerical model to elucidate the mechanisms for the formation of the turbidity maximum and intratidal variations in fine sediment transport process.…”

Section: Introductionmentioning

confidence: 99%

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Response of the turbidity maximum zone in the Yangtze River Estuary due to human activities during the dry season

Chen

Shen

Yang

2016

Environ Sci Pollut Res

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The interaction between a river and the sea results in a turbidity maximum zone (TMZ) within the estuary, which has a great impact on the local ecosystem. In the Yangtze River Estuary, the magnitude and extent of the TMZ vary with water discharge. In this study, the cumulative human activity altered the water discharge regime from the river to the estuary. In the post-Three Gorges Dam (TGD) period, water discharge increased by 35.10 % at Datong in February compared with that in the pre-TGD period. The effects of water discharge variation on the characteristics of the TMZ were analyzed during spring and neap tidal periods using the three-dimensional environmental fluid dynamic code (EFDC) model. The area of the TMZ decreased by 3.11 and 17.39 % during neap and spring tides, respectively. In addition, the upper limit of the TMZ moved 11.68 km seaward during neap tide, whereas the upper limit of the TMZ in the upstream and downstream areas moved seaward 9.65 and 2.34 km, respectively, during spring tide. These findings suggest that the area and location of the TMZ are more sensitive to upstream runoff during spring tide than during neap tide. These changes in the TMZ will impact the biochemical processes in the Yangtze River Estuary. In the foreseeable future, the distribution characteristic of TMZ will inevitably change due to variations in the Yangtze River discharge resulting from new human activities (i.e., new dams), which are being constructed upstream in the Yangtze River system.

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“…Estuaries form complex and variable linkages between fluvial and marine environments acting as effective sediment traps (Biggs and Howell, 1984;Woodruff et al, 2001), and typically developing a turbidity maximum zone (TMZ) with highest suspended solid concentrations at the beginning of the saline intrusion (Morris et al, 1982;Wu et al, 2012). Dissolve-particulate phase changes and prevailing adsorption onto heterogeneously distributed solids peaking at the TMZ strongly condition the overall dynamics and fate of trace metals in estuarine environments (Hughes et al, 1998).…”

Section: Introductionmentioning

confidence: 99%

Trace metal behavior along fluvio-marine gradients in the Samborombón Bay, outer Río de la Plata estuary, Argentina

Tatone

Bilos

Skorupka

et al. 2015

Continental Shelf Research

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Sediment trapping of turbidity maxima in the Changjiang Estuary

Cited by 98 publications

References 49 publications

Longitudinal variation in lateral trapping of fine sediment in tidal estuaries: observations and a 3D exploratory model

Longitudinal variation in lateral trapping of fine sediment in tidal estuaries: observations and a 3D exploratory model

Response of the turbidity maximum zone in the Yangtze River Estuary due to human activities during the dry season

Trace metal behavior along fluvio-marine gradients in the Samborombón Bay, outer Río de la Plata estuary, Argentina

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