Laboratory flume studies on monochromatic wave-fine sandy bed interactions Part 2. Sediment suspensions

Tzang, Shiaw-Yih; Ou, Shan‐Hwei; Hsu, Tai‐Wen

doi:10.1016/j.coastaleng.2008.07.005

Cited by 31 publications

(10 citation statements)

References 23 publications

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“…During the initial period of the 7 cm height wave loading, the initial SSCs increased rapidly due to wave disturbance. This was similar with the SSC variation in the wave flume experiment conducted by Tzang et al (2009). Under wave loads, the vertical distribution of pore pressure had depth gradients with a maximum value at a certain depth in sediment [37,38].…”

Section: Variations Of Sscs In the Overlying Watersupporting

confidence: 83%

“…Under wave loads, the vertical distribution of pore pressure had depth gradients with a maximum value at a certain depth in sediment [37,38]. Once the sediment liquefaction initiated, pore pressure generally amplified in both shallow fluidized soil layers and near below the fluidized layer [23]. Thus, fine particles and pore water at this depth transported upwards from the interior of sediment under the "pumping" effect of pore water pressure [22,39], and caused higher initial rises of SSCs.…”

Section: Variations Of Sscs In the Overlying Watermentioning

confidence: 99%

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Migration and Diffusion of Heavy Metal Cu from the Interior of Sediment during Wave-Induced Sediment Liquefaction Process

Lü

Zhang

Jia

et al. 2019

JMSE

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Sediments are an important sink for heavy metal pollutants on account of their strong adsorption capacity. Elevated content of Cu was observed in the Chengdao area of the Yellow River Delta, where the surface sediment is mainly silt and is prone to be liquefied under hydrodynamic forces. The vertical transport of fine particles, along with pore water seepage, during the liquefaction process could promote the migration and diffusion of Cu from the interior of sediment. The present study involved a series of wave flume experiments to simulate the migration and diffusion of Cu from the interior of sediment in the subaqueous Yellow River Delta area under wave actions. The results indicated that sediment liquefaction significantly promoted the release of Cu from internal sediment to overlying water. The variations of Cu concentrations in the overlying water were opposite to the suspended sediment concentrations (SSCs). The sediment liquefaction caused high initial rises of SSCs, but led to a rapid decline of dissolved Cu concentration at the initial period of sediment liquefaction due to the adsorption by fine particles. Afterwards, the SSCs slightly increased and then gradually decreased. Meanwhile, the dissolved Cu concentration generally kept increasing under combined effects of intensively mix of sediment and overlying water, pore water seepage, and desorption. The dissolved Cu concentration in the overlying water during sediment liquefaction phase was 1.5–2.2 times that during the consolidation phase. Sediment liquefaction also caused vertical diffusion of Cu in sediment and the diffusion depth was in accordance with the liquefaction depth. The results of the present study may provide reference for the environmental management in the study area.

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Section: Variations Of Sscs In the Overlying Watersupporting

confidence: 83%

Section: Variations Of Sscs In the Overlying Watermentioning

confidence: 99%

Migration and Diffusion of Heavy Metal Cu from the Interior of Sediment during Wave-Induced Sediment Liquefaction Process

Lü

Zhang

Jia

et al. 2019

JMSE

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“…Time-average of low-frequency wave oscillatory component rigid rod separated by the sample volume with the difference in nearinfrared intensity (due to absorption and reflection) between the two fibers related to the SSC (e.g. Tzang et al, 2009;Van Der Ham et al, 2001). A filter prevents ambient light from influencing the measurements.…”

Section: Sediment Concentrationsmentioning

confidence: 99%

Spectral wave-driven sediment transport across a fringing reef

Pomeroy

Lowe

Dongeren

et al. 2015

Coastal Engineering

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a b s t r a c tA laboratory experiment was conducted to investigate the dynamics of cross-shore sediment transport across a fringing coral reef. The aim was to quantify how a highly bimodal spectrum of high-frequency (sea-swell) and low-frequency (infragravity and seiching) waves that is typically present on coral reef flats, influences the various sediment transport mechanisms. The experiments were conducted in a 55 m wave flume, using a 1:15 scale fringing reef model that had a 1:5 forereef slope, a 14 m long reef flat, and a 1:12 sloping beach. The initial 7 m of reef flat had a fixed bed, whereas the back 7 m of the reef and the beach had a moveable sandy bed. Four seven-hour irregular wave cases were conducted both with and without bottom roughness elements (schematically representing bottom friction by coral roughness), as well as for both low and high still water levels. We observed that the wave energy on the reef flat was partitioned between two primary frequency bands (high and low), and the proportion of energy within each band varied substantially across the reef flat, with the lowfrequency waves becoming increasingly important near the shore. The offshore transport of suspended sediment by the Eulerian mean flow was the dominant transport mechanism near the reef crest, but a wide region of onshore transport prevailed on the reef flat where low-frequency waves were very important to the overall transport. Ripples developed over the movable bed and their properties were consistent with the local highfrequency wave orbital excursion lengths despite substantial low-frequency wave motions also present on the reef flat. This study demonstrated that while a proportion of the sediment was transported by bedload and mean flow, the greatest contributions to cross-shore transport were due to the skewness and asymmetry of the high and low-frequency waves.

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“…Using wave‐induced bottom shear stress only may underestimate the importance of waves to sediment dynamics as waves play a significant role to fluidize beds, especially in silt‐rich seabed (Green & Coco, 2014). Laboratory studies suggest that the suspended sediment load is positively correlated to wave height and liquefaction level (Jia et al., 2014; Tzang et al., 2009). Numerous observation data deployed in different coastal areas suggest wave‐induced pore pressure buildup can change the consolidation state and further increase bed erodibility (Klammler et al., 2021; Lambrechts et al., 2010; Liu et al., 2020; Sanford, 1994; Wolanski & Spagnol, 2003; Wolanski et al., 1995).…”

Section: Introductionmentioning

confidence: 99%

Importance of Bed Liquefaction‐Induced Erosion During the Winter Wind Storm in the Yellow River Delta, China

Niu,

Xie,

Lin

et al. 2023

JGR Oceans

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Data obtained during a 5‐month field observation of the Yellow River Delta show that the storm wave‐related oscillatory flows are mainly in an intermittently turbulent regime (400 < ReΔ < 1,200). Wave‐induced seabed liquefaction causes changes to the bed erodibility and increases the sediment entrainment rate, resulting in the formation of fluid mud layer (FML) during winter wind events. The strong NE winter winds lead to most of the wave‐induced liquefaction events in the study area. It was found the sediment erosion rate is underestimated when we solely focus on the wave‐induced bottom shear stress. To parameterize wave‐induced excess pore pressure buildup and sediment liquefaction, a series of experiments were conducted in a large wave flume and a new liquefaction‐erosion method is proposed to calculate the sediment erosion flux. Analysis of model results shows that the FML thickness is about 2–12 cm at the storm‐arrival stage during the entire observation period. The thickness of FML significantly increases with the increase of wave height and decrease of water depth. Once the FML is formed, strong currents can remove fluid mud 10 hr after the storm‐arrival stage, while the background currents on calm days can hardly cause suspension. The erosion rate in liquefaction zones can increase 5–10 times compared with the erosion rate in nonliquefaction conditions. The whole Bohai Sea is highly turbid after intense NE winter wind, and the liquefaction zones during winter winds would be the major sediment source. Enhanced sediment erosion can cause the subsequent degradation of the subaqueous Yellow River Delta.

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Laboratory flume studies on monochromatic wave-fine sandy bed interactions Part 2. Sediment suspensions

Cited by 31 publications

References 23 publications

Migration and Diffusion of Heavy Metal Cu from the Interior of Sediment during Wave-Induced Sediment Liquefaction Process

Migration and Diffusion of Heavy Metal Cu from the Interior of Sediment during Wave-Induced Sediment Liquefaction Process

Spectral wave-driven sediment transport across a fringing reef

Importance of Bed Liquefaction‐Induced Erosion During the Winter Wind Storm in the Yellow River Delta, China

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