Numerical modeling of hyperpycnal plume

Khan, Sadia M.; Imran, Jasim; Bradford, Scott F.; Syvitski, James P. M.

doi:10.1016/j.margeo.2005.06.025

Cited by 33 publications

(31 citation statements)

References 27 publications

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“…Suppose the presence of point-source input of river sediment in a tidal estuary imposes a longitudinal density gradient along the bottom due to the influence of the sediment concentration on water density, a sediment gravity current (hyperpycnal plume) will be generated as observed by Wright et al (2001), Scully et al (2002), and Khan et al (2005). In the Huanghe (Yellow River) mouth, the flow associated with hyperpycnal plume (hyperpycnal flow) can reach up to 0.4 m/s where sediment-induced water density anomaly is in the order of 10 kg/m 3 (Wright et al 1988(Wright et al , 1990.…”

Section: Introductionmentioning

confidence: 99%

Tidal straining effect on the suspended sediment transport in the Huanghe (Yellow River) Estuary, China

Wang

2010

Ocean Dynamics

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Tidal straining effect on sediment transport dynamics in the Huanghe (Yellow River) estuary was studied by field observations and numerical simulations. The measurement of salinity, suspended sediment concentration, and current velocity was conducted during a flood season in 1995 at the Huanghe river mouth with six fishing boats moored at six stations for 25-h hourly time series observations. Based on the measurements, the intra-tidal variations of sediment transport in the highly turbid river mouth was observed and the tidal straining effect occurred. Our study showed that tidal straining of longitudinal sediment concentration gradients can contribute to intratidal variability in sediment stratification and to asymmetries in sediment distribution within a tidal cycle. In particular, the tidal straining effect in the Huanghe River estuary strengthened the sediment-induced stratification at the flood tide, thus producing a higher bottom sediment concentration than that during the ebb. A sediment transport model that is capable of simulating sediment-induced stratification effect on the hydrodynamics in the bottom boundary layers and associated density currents was applied to an idealized estuary to demonstrate the processes and to discuss the mechanism. The model-predicted sediment processes resembled the observed characteristics in the Huanghe River estuary. We concluded that tidal straining effect is an important but poorly understood mechanism in the transport dynamics of cohesive sediments in turbid estuaries and coastal seas.

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Section: Introductionmentioning

confidence: 99%

Tidal straining effect on the suspended sediment transport in the Huanghe (Yellow River) Estuary, China

Wang

2010

Ocean Dynamics

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“…Behaviors of hyperpycnal flows remain unclear due to difficulties on in-situ field observations. However, numerical modeling and experimental works (Khan et al 2005 and reference therein) point out that current speed, direction, and the seafloor slope are important factors determining its discharge. Additionally, recent modeling has shown that a turbidity current can move in an opposite direction from the overlying current as the two flows often decouple during a serious hyperpycnal flood.…”

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confidence: 99%

Sediment Budget in the Taiwan Strait with High Fluvial Sediment Inputs from Mountainous Rivers: New Observations and Synthesis

Kao¹,

Jan²,

Hsu³

et al. 2008

Terr. Atmos. Ocean. Sci.

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The shallow Taiwan Strait at the southern opening of the East China Sea (ECS) receives abundant sediments from turbid mountainous rivers in Taiwan. The volume of sediment is among the highest sediment yields on the global surface. This large amount of sediment discharged from modern Taiwan (range: 175 -380 Mt y -1 based on 50-yr data) is comparable to that discharged from Changjaing (500 Mt y -1 -decreasing in recent decades), underscoring the importance of sediment budget in the Taiwan Strait and sediment flux from Taiwan into the ECS. We documented fluvial mud and sand concentrations during flash flooding with our observations indicating that fluvial materials in Taiwan's rivers are chiefly composed of mud (> 70% and up to 98%). By contrast, sand fraction dominates (> 85% for most stations) surface sediments in the Taiwan Strait. Super typhoon Herb alone delivered 130 Mt of sediments from Choshui, the largest river in Taiwan, yet only insignificant amounts of mud were found at the river mouth six months later. The actions of waves, tides, and currents apparently prevent the deposition of fine grained sediments. Assuming sand occupied 30% (the maximum) of the 60 Mt y -1 total sediment input from major western Taiwanese rivers, our annual budget estimate shows that the amount of sand input (18 ± 5 Mt y -1 ) is comparable to the burial output of sand (12 ± 10 Mt y -1 ). However, mud burial (6 ± 5 Mt y -1 ) in the strait is far below the estimated mud input (42 ± 11 Mt y -1 ), resulting in a significant shortfall. Hydrodynamic conditions were synthesized to explain the distribution pattern of limited mud patches in the strait and to reveal potential pathways by which fine-grain sediment transportation takes place in the seas surrounding Taiwan. A significant shortfall in the mud budget in the Taiwan Strait suggests that~85% of the fluvial mud left the strait. Alternatively, the 50-year modern sediment flux data used in this study reflects exacerbated sediment flux due to human activity and is possibly too high to represent loads during pre-Anthropocene. Additional studies are needed to explore the flux and fate of mud in and surrounding Taiwan over a longer time scale.

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“…The undulations of the study area display an along-slope trend that is compatible with their interpretation as the product of hyperpycnal flows. Furthermore, several Apennine Rivers are likely to develop hyperpycnal discharges (Khan et al 2005). However, differently from most undulations produced by turbidity currents and hyperpycnal flows, the observed undulations are apparently standing with no evident signs of migration, change their wavelength from one to another without any appreciable trend, and are unrelated to erosional features.…”

Section: Seafloor Undulations With Internal Layered Seismic Faciesmentioning

confidence: 93%

Morphobathymetric analysis and evidence of submarine mass movements in the western Gulf of Taranto (Calabria margin, Ionian Sea)

Rebesco

Neagu

Cuppari

et al. 2009

Int J Earth Sci (Geol Rundsch)

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The western part of the Gulf of Taranto, southern Italy, is a seismically active area with high sediment supply. New swath bathymetry and sub-bottom profiler (CHIRP) data were acquired on board R/V OGSExplora during the WGDT cruise. The data were analyzed to describe the seafloor morphology and the acoustic facies of relevant morphologic features. Special attention was given to the features produced by mass wasting and softsediment deformations. The features identified include: slides and slide scars, debris flow deposits, enigmatic dipslope trending sub-parallel linear depressions, and alongslope undulations inferred to have been produced either by creeping or sediment deposition by hyperpycnal flows. The description of these features contributes to the characterization of the Calabria foreland basin system and provides an analogue for other basins similarly affected by a close relation between sediment supply and active tectonics.

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Numerical modeling of hyperpycnal plume

Cited by 33 publications

References 27 publications

Tidal straining effect on the suspended sediment transport in the Huanghe (Yellow River) Estuary, China

Tidal straining effect on the suspended sediment transport in the Huanghe (Yellow River) Estuary, China

Sediment Budget in the Taiwan Strait with High Fluvial Sediment Inputs from Mountainous Rivers: New Observations and Synthesis

Morphobathymetric analysis and evidence of submarine mass movements in the western Gulf of Taranto (Calabria margin, Ionian Sea)

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