Estimation of critical shear stress for erosion in the <scp>C</scp>hangjiang <scp>E</scp>stuary: A synergy research of observation, <scp>GOCI</scp> sensing and modeling

Ge, Jianzhong; Shen, Fang; Guo, Wenyun; Chen, Changsheng; Ding, Pingxing

doi:10.1002/2015jc010992

Cited by 57 publications

(53 citation statements)

References 72 publications

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“…For cohesive sediment transport, the key parameters are the settling velocity ω s and the critical shear stress τ cr for erosion in the Partheniades‐Krone formulation. Based on empirical formulations (Ge et al, ; Luan et al, ), we set uniform τ cr values ranging from 0.05 to 0.5 N and a settling velocity of 0.2 mm/s. After releasing the cohesive sediment in the water column, the model was run with a fixed bed for 1 month.…”

Section: Resultsmentioning

confidence: 99%

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: Resultsmentioning

confidence: 99%

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

et al. 2018

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“…Two parallel dikes and many perpendicular groynes were built along the North Passage, which were designed to increase the flow energy in the main channel and hence to reduce sediment siltation and deepen the channel (Ge et al, ; Pan et al, ). As the consequence of deepened channel, the dike‐groyne construction has physically trapped the sediment and made the North Passage the most energetic channel with significant variability of sediment concentration (Ge et al, , , ; Li et al, ; Pan et al, ).…”

Section: Study Sites and Designs Of Field Measurementsmentioning

confidence: 99%

“…It is a gateway for sand and mud from the terrestrial source to sink in the marine environment. The mud suspension in the turbidity maximum zone produces a significant mass exchange between the water column and seabed, which can have great impacts on hydrodynamics, morphological development, ecosystem, and biogeochemistry at either local or regional scale (Ge et al, ; Geyer & MacCready, ; Toublanc et al, ; Winterwerp, ; Winterwerp & Van Kesteren, ). The concentrated benthic suspension (CBS) of mud can frequently occur around an estuary as a result of sediment deposition, mass or bulk erosion, and convergence under physical mechanisms (Bruens et al, ; Sottolichio & Castaing, ; Winterwerp, , ).…”

Section: Introductionmentioning

confidence: 99%

Formation of Concentrated Benthic Suspension in a Time‐Dependent Salt Wedge Estuary

Zhou

Yang

et al. 2018

JGR Oceans

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The concentrated benthic suspension (CBS) of mud, as a major contributor of sediment transport in the turbidity maximum of the estuary, is of great challenge to be correctly monitored through field measurements, and its formation mechanism is not well understood. A tripod system equipped with multiple instruments was deployed to measure the near‐bed hydrodynamics and sediments in the North Passage of the Changjiang Estuary, with the aim at determining the formation mechanisms of CBS. The measurements detected a significant dominance of high sediment concentration in the near‐bed 1‐m layer: ~20 g/L at the southern site and ~47 g/L at the northern site. Strong CBS occurred under weak tidal mixing condition and was directly relevant to the sediment‐induced suppression of turbulent kinetic energy and the enhanced water stratification due to saltwater intrusion and sediment suspension. During the weak‐mixing neap period, the typical thickness of CBS was about 0.2–0.3 m, with a life time of ~2.83 hr (suspended‐sediment concentration > 15.0 g/L). Enhanced water stratification reduced vertical mixing and confined the sediment entrainment from the near‐bed layer to the upper column. This enhancement was due to the suppression of turbulent kinetic energy as a result of the sediment accumulation in the near‐bottom column during the slack waterand also due to the appearance of a two‐layer salinity structure in the vertical as a result of saltwater intrusion near the bottom. These physical processes worked as a positive feedback loop during the formation of CBS and can be simulated with a process‐oriented, one‐dimensional vertical CBS model.

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“…The section from 121.7 • N to 122.4 • N is located in the maximum turbidity zone of the Yangtze Estuary, with the highest [SPM] and relatively large spatiotemporal variations. It results from the intense interaction between the river runoff and tidal currents in the maximum turbidity zone of the Yangtze Estuary that leads to resuspension of bottom sediments [49]. The exchange of materials and waters between the channels and tidal flats was strong under complex hydrodynamic conditions [48,50].…”

Section: The Spatiotemporal Variations Of [Spm]mentioning

confidence: 99%

“…The obvious edges of its transition were the locations of the DWP jetties [51,52], which were also located in the spikes labeled by I, II and III in Figure 7d. From the view of the cross-section shown in Figure 14 turbidity zone of the Yangtze Estuary that leads to resuspension of bottom sediments [49]. The exchange of materials and waters between the channels and tidal flats was strong under complex hydrodynamic conditions [48,50].…”

Section: The Spatiotemporal Variations Of [Spm]mentioning

confidence: 99%

Fusion of Landsat-8/OLI and GOCI Data for Hourly Mapping of Suspended Particulate Matter at High Spatial Resolution: A Case Study in the Yangtze (Changjiang) Estuary

2018

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Suspended particulate matter (SPM) concentrations ([SPM]) in the Yangtze estuary, which has third-order bifurcations and four outlets, exhibit large spatial and temporal variations. Studying the characteristics of these variations in [SPM] is important for understanding sediment transport and pollutant diffusion in the estuary as well as for the construction of port and estuarine engineering structures. The 1-h revisit frequency of the Geostationary Ocean Color Imager (GOCI) sensor and the 30-m spatial resolution of the Landsat 8 Operational Land Imager (L8/OLI) provide a new opportunity to study the large spatial and temporal variations in the [SPM] in the Yangtze estuary. In this study, [SPM] images with a temporal resolution of 1 h and a spatial resolution of 30 m are generated through the product-level fusion of [SPM] data derived from L8/OLI and GOCI images using the Spatial and Temporal Adaptive Reflectance Fusion Model (STARFM). The results show that the details and accuracy of the spatial and temporal variations are maintained well in the [SPM] images that are predicted based on the fused images. Compared to the [SPM] observations at fixed field stations, the mean relative error (MRE) of the predicted SPM is 17.7%, which is lower than that of the GOCI-derived [SPM] (27.5%). In addition, thanks to the derived high-resolution [SPM] with high spatiotemporal dynamic changes, both natural phenomena (dynamic variation of the maximum turbid zone) and human engineering changes leading to the dynamic variability of SPM in the channel are observed.

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Estimation of critical shear stress for erosion in the Changjiang Estuary: A synergy research of observation, GOCI sensing and modeling

Cited by 57 publications

References 72 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

Formation of Concentrated Benthic Suspension in a Time‐Dependent Salt Wedge Estuary

Fusion of Landsat-8/OLI and GOCI Data for Hourly Mapping of Suspended Particulate Matter at High Spatial Resolution: A Case Study in the Yangtze (Changjiang) Estuary

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