A laboratory study on sediment resuspension within arrays of rigid cylinders

Tinoco, Rafael O.; Coco, Giovanni

doi:10.1016/j.advwatres.2016.04.003

Cited by 83 publications

(105 citation statements)

References 31 publications

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“…Yang et al () showed that k t is a better predictor of the threshold of sediment motion than τ and that the critical level of near‐bed turbulence is the same in bare and vegetated channels. Similarly, Tinoco and Coco (, ) showed that resuspension of sediment within an array of model vegetation is better predicted by a metric based on k t than τ . Finally, Yang and Nepf () demonstrated that the bed load transport rate, Q s , was better correlated with k t than τ , and they attributed the dependence of Q s on k t to the fact that the lift force on the sediment grains, which initiates sediment transport (e.g., Nino & Garcia, ; Sumer & Oguz, ; Vollmer & Kleinhans, ; Zanke, ), scales with k t (Batchelor, ; Dittrich, ; Zanke, ).…”

Section: Introductionmentioning

confidence: 93%

“…Previous studies have described the impact of turbulent structures (e.g., Nelson et al, ), velocity fluctuations (e.g., Sumer et al, ), and the duration of the peak velocity (e.g., Diplas et al, ) on bed load transport. Recent studies demonstrated that, in regions with vegetation, sediment transport is more closely correlated with turbulent kinetic energy, k t , than with the time‐mean bed stress ( τ ) (Tinoco & Coco, , ; Yang & Nepf, ; Yager & Schmeeckle, ; Yang et al, ). Specifically, within a channel of model vegetation, Yager and Schmeeckle () observed that regions of high bed load transport are correlated with high near‐bed turbulence.…”

Section: Introductionmentioning

confidence: 99%

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Impact of Vegetation on Bed Load Transport Rate and Bedform Characteristics

Yang

Nepf

2019

Water Resources Research

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The impacts of aquatic vegetation on bed load transport rate and bedform characteristics were quantified using flume measurements with model emergent vegetation. First, a model for predicting the turbulent kinetic energy, kt, in vegetated channels from channel average velocity U and vegetation volume fraction ϕ was validated for mobile sediment beds. Second, using data from several studies, the predicted kt was shown to be a good predictor of bed load transport rate, Qs, allowing Qs to be predicted from U and ϕ for vegetated channels. The control of Qs by kt was explained by statistics of individual grain motion recorded by a camera, which showed that the number of sediment grains in motion per bed area was correlated with kt. Third, ripples were observed and characterized in channels with and without model vegetation. For low vegetation solid volume fraction (ϕ ≤ 0.012), the ripple wavelength was constrained by stem spacing. However, at higher vegetation solid volume fraction (ϕ=0.025), distinct ripples were not observed, suggesting a transition to sheet flow, which is sediment transport over a plane bed without the formation of bedforms. The fraction of the bed load flux carried by migrating ripples decreased with increasing ϕ, again suggesting that vegetation facilitated the formation of sheet flow.

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Section: Introductionmentioning

confidence: 93%

Section: Introductionmentioning

confidence: 99%

Impact of Vegetation on Bed Load Transport Rate and Bedform Characteristics

Yang

Nepf

2019

Water Resources Research

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“…Plants also bend or break in rapid unidirectional flows, offering less resistance to the flow, thus losing much of their dampening effect. Unlike dense aquatic meadows, sparse submerged canopies can enhance local turbulence, causing increased bed shear stress, and thus potential scour near the base of the plants …”

Section: Supply Of Coastal Protection Servicesmentioning

confidence: 99%

Linking social, ecological, and physical science to advance natural and nature‐based protection for coastal communities

Arkema

Griffin

Maldonado

et al. 2017

Annals of the New York Academy of Sciences

125

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Interest in the role that ecosystems play in reducing the impacts of coastal hazards has grown dramatically. Yet the magnitude and nature of their effects are highly context dependent, making it difficult to know under what conditions coastal habitats, such as saltmarshes, reefs, and forests, are likely to be effective for saving lives and protecting property. We operationalize the concept of natural and nature-based solutions for coastal protection by adopting an ecosystem services framework that propagates the outcome of a management action through ecosystems to societal benefits. We review the literature on the basis of the steps in this framework, considering not only the supply of coastal protection provided by ecosystems but also the demand for protective services from beneficiaries. We recommend further attention to (1) biophysical processes beyond wave attenuation, (2) the combined effects of multiple habitat types (e.g., reefs, vegetation), (3) marginal values and expected damage functions, and, in particular, (4) community dependence on ecosystems for coastal protection and co-benefits. We apply our approach to two case studies to illustrate how estimates of multiple benefits and losses can inform restoration and development decisions. Finally, we discuss frontiers for linking social, ecological, and physical science to advance natural and nature-based solutions to coastal protection.

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“…The recorded time series were decomposed into timeframe space, and the dominant modes of variability and their variation in time were analysed as described in Grinsted et al (2004). To limit the edge effects, the time series represented the region of spectrum where the effects might have been important (near large scales) by a "cone of influence" (COI) following Torrence and Compo (1998). Farge (1992) suggested that continuous wavelet transform (CWT) unfolds the dynamics of coherent structures and measures their contribution to energy spectrum.…”

Section: Data Analysis Techniquesmentioning

confidence: 99%

“…Wavelet analysis was used to identify localized variations of power within the time series (Torrence and Compo, 1998). The recorded time series were decomposed into timeframe space, and the dominant modes of variability and their variation in time were analysed as described in Grinsted et al (2004).…”

Section: Data Analysis Techniquesmentioning

confidence: 99%

The influence of turbulent bursting on sediment resuspension under unidirectional currents

et al. 2017

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Abstract. Laboratory experiments were conducted in an open channel flume with a flat sandy bed to examine the role of turbulence on sediment resuspension. An acoustic Doppler velocimeter (ADV) was used to measure the instantaneous three-dimensional velocity components and acoustic backscatter as a proxy to suspended sediment concentration. Estimates of sediment transport assume that there is a mean critical velocity that needs to be exceeded before sediment transport is initiated. This approach does not consider the turbulent flow field that may initiate sediment resuspension through event-based processes such as the "bursting" phenomenon. In this paper, laboratory measurements were used to examine the sediment resuspension processes below and above the mean critical velocity. The results within a range above and below the measured mean critical velocity suggested that (1) the contribution of turbulent bursting events remained identical in both experimental conditions, (2) ejection and sweep events contributed more to the total sediment flux than up-acceleration and down-deceleration events, and (3) wavelet transform revealed a correlation between the momentum and sediment flux in both test conditions. Such similarities in conditions above and below the measured mean critical velocity highlight the need to re-evaluate the accuracy of a single time-averaged mean critical velocity for the initiation of sediment entrainment.

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A laboratory study on sediment resuspension within arrays of rigid cylinders

Cited by 83 publications

References 31 publications

Impact of Vegetation on Bed Load Transport Rate and Bedform Characteristics

Impact of Vegetation on Bed Load Transport Rate and Bedform Characteristics

Linking social, ecological, and physical science to advance natural and nature‐based protection for coastal communities

The influence of turbulent bursting on sediment resuspension under unidirectional currents

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