In situ estimation of erosion and deposition thresholds by Acoustic Doppler Velocimeter (ADV)

Andersen, Thorbjørn Joest; Fredsøe, Jørgen; Pejrup, Morten

doi:10.1016/j.ecss.2007.04.039

Cited by 99 publications

(80 citation statements)

References 41 publications

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“…In addition, significant linear relationships were found between settling velocity and other parameters (e.g., floc size, turbulence, SSC, effective density, and fractal dimension) at the two sites, indicating that the factors controlling settling velocity are spatially variable. The results are also consistent with the findings of Andersen et al (2007) and Salehi and Strom (2012), who concluded that LP and Cov a r e t h e m o s t a p p r o p r i a t e m e t h o d s t o a p p l y i n current-dominated environments.…”

Section: Discussionsupporting

confidence: 94%

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On the variability of near-bed floc size due to complex interactions between turbulence, SSC, settling velocity, effective density and the fractal dimension of flocs

Yang

Wang

et al. 2016

Geo-Mar Lett

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Interactions between turbulence, suspended sediment concentration (SSC), settling velocity, effective density, fractal dimension, and floc size were studied on the tide-dominated, muddy coastal shelf of the southwestern Yellow Sea, China. The measurements were carried out in July 2013 at two sites located in water depths of 21.2 and 22.1 m. Negative correlations were observed between shear rate, SSC, effective density, and mean floc size, which supports the results of previous numerical, experimental, and field studies. A significant positive correlation was observed between near-bed SSC and shear rate, an indication that SSC variations are controlled by turbulence and re-suspension. In addition, significant linear relationships were found between settling velocity and other parameters (floc size, turbulence, SSC, effective density, and fractal dimension) at the two sites, indicating that the controlling factors on settling velocity are spatially variable. Principal component analysis was applied to determine the relative importance of turbulence, flocculation ability, and SSC as controls on floc size in situ. The relative contributions of turbulence, flocculation ability, and SSC to floc size (at both sites) were~33.0%, 30.3%, and 29.7%, respectively, this being a new field-based quantitative analysis of the controls on floc size. The findings demonstrate that, in nature, flocculation ability affects floc size to the same degree as turbulence and SSC. Therefore, predictions of floc size in coastal marine environments require constraints not only on turbulence and SSC, but also on flocculation ability.

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Section: Discussionsupporting

confidence: 94%

“…4 is theoretically based. Andersen et al (2007) and Salehi and Strom (2012) recommended the use of maximum instantaneous velocity when estimating bed shear stresses in regions characterized by strongly fluctuating velocities.…”

Section: Estimates Of Shear Ratementioning

confidence: 99%

On the variability of near-bed floc size due to complex interactions between turbulence, SSC, settling velocity, effective density and the fractal dimension of flocs

Yang

Wang

et al. 2016

Geo-Mar Lett

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“…Results from Scenario 3 show that the worst-case condition for the intake occurs at the beginning of flood tide (identified by Number 2 in Figure 9) and ebb tide (identified by Number 5 in Figure 9). This is reasonable as the highest current velocity and shear stress is known to occur during the first flood and last ebb in an estuarine setting [29,30]. Surface temperature during the same period and season is shown in Figure 10 for a condition with outfall location almost 400 m farther from its location in Scenario 3.…”

Section: Resultsmentioning

confidence: 64%

Thermal Recirculation Modeling for Power Plants in an Estuarine Environment

Salehi¹

2017

JMSE

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Many power plants require large quantities of water for cooling purposes. The water taken from the source water body (e.g., lakes, estuaries, bays and rivers) circulates through the plant and returns to the source through outfall with a higher temperature. For optimal performance of the power plant, the intake inlet and discharge outlet should be meticulously placed so that the heated water will not recirculate back into the power plant. In this study, the Flow module of the Delft3D software is employed to simulate the temperature transport within the study area in three-dimensional and nested format. Model results are used to optimize the location of intake inlets, outfall outlets and diffuser port orientations. The physical processes used in the study are tidal fluctuations, winds, river discharges, salinity and temperature. The subject power plant (power plant parameters presented in this paper are realistic; however, they do not target any specific power plant within the study area) has a nominal capacity of 2600 MW and is planned to be located in Delaware Bay, USA. Existing field measurements are used to calibrate the model in a coupled two-staged fashion for main tidal constituents, currents and water temperature. The sensitivity of the model against various input parameters is tested, and conservative values are selected. The location of the intake is fixed, and the location of the outfall is changed until the thermal impact to the intake is less than 1 • C. Analysis of the results shows that there is a linear logarithmic relation between the excess temperatures at the intake inlet and horizontal eddy diffusivity. The k − turbulence closure results in higher excess temperature and a more conservative design. Extending the outfall location to the deeper portion of the estuary combined with port orientations reduces the impact by keeping the thermal plume away from the intake inlet and meeting the established criteria. It is concluded that an approximate distance of 1300 m is the optimal location for the power plant outfall outlets. In addition, the diffuser ports should not discharge the heated water toward the intake and have to be oriented away from the line connecting outfall to the intake.

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“…With climate change predicted to increase the number of extreme events in many regions the use of erosion devices to determine erosion response and associated chemical release is becoming increasingly important (Statham, 2012). Unfortunately, interpretation of erosion chamber results are hampered by poor comparisons between devices (Tolhurst et al, 2000b;Widdows et al, 2007) and lack of direct comparison between erosion chamber results and field observations (Andersen et al, 2007). Robust validation of the chambers requires high resolution observations of the velocity field, as a proxy for in situ shear stress, in the lowest few centimeters of the water column, with concomitant observation of sediment erosion.…”

Section: Introductionmentioning

confidence: 99%

Field and laboratory observations of bed stress and associated nutrient release in a tidal estuary

Wengrove

Foster

Kalnejais

et al. 2015

Estuarine, Coastal and Shelf Science

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In situ estimation of erosion and deposition thresholds by Acoustic Doppler Velocimeter (ADV)

Cited by 99 publications

References 41 publications

On the variability of near-bed floc size due to complex interactions between turbulence, SSC, settling velocity, effective density and the fractal dimension of flocs

On the variability of near-bed floc size due to complex interactions between turbulence, SSC, settling velocity, effective density and the fractal dimension of flocs

Thermal Recirculation Modeling for Power Plants in an Estuarine Environment

Field and laboratory observations of bed stress and associated nutrient release in a tidal estuary

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