Flow dynamics and sediment transport in vegetated rivers: A review

Journal of Hydrodynamics, Год журнала: 2021, Номер 33(3), С. 400 - 420

Опубликована: Июнь 1, 2021

Язык: Английский

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Turbulence affected by submerged aquatic vegetation under wind-induced flow

Physics of Fluids, Год журнала: 2025, Номер 37(1)

Опубликована: Янв. 1, 2025

Submerged aquatic vegetation (SAV) changes the turbulent structure of rivers, wetlands, estuaries, and lakes. However, few studies have focused on influence SAV hydrodynamic characteristics under wind-induced flow. Therefore, laboratory experiments were conducted to study effects flow turbulence flow, spectral based decomposition method was used separate wave velocity. Result shows that reduced local velocity within canopy elevates location zero-velocity point. The drag caused by increases decay rate Reynolds stress along depth while hardly influencing stress. Canopy depresses RMS (root mean square) orbital presence leads decrease in TKE (turbulent kinetic energy) production dissipation canopy. more effectively diminishes than it does dissipation. Research isotropy flows promotes a gradual transition from anisotropy Finally, quadrant analysis reveals probabilities contribution momentum ejection sweep.

Язык: Английский

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Impact of Stem Size on Turbulence and Sediment Resuspension Under Unidirectional Flow

Water Resources Research, Год журнала: 2021, Номер 57(3)

Опубликована: Фев. 17, 2021

Abstract Laboratory experiments examined the impact of model vegetation on turbulence and resuspension. The turbulent kinetic energy increased with increasing velocity solid volume fraction, but did not depend stem diameter. vegetation‐generated dominated total inside canopies. For same sediment size, critical at which resuspension was initiated for both vegetated bare beds, resulted in a that decreased fraction. Both had no dependence However, denser canopies and/or canopy smaller greater slope is required to initiate This study provides way predict onset regions vegetation, an important threshold transport landscape evolution.

Язык: Английский

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Turbulence in a channel with a patchy submerged canopy: the impact of spatial configuration

Journal of Fluid Mechanics, Год журнала: 2025, Номер 1006

Опубликована: Март 7, 2025

This study investigates how the spatial configuration of submerged three-dimensional patches vegetation impacts turbulence. Laboratory experiments were conducted in a channel with model configured different patch area densities ( $\phi _{p}$ ), representing bed fraction occupied by patches, ranging from 0.13 to 0.78, and patterns transitioning two dimensional (channel-spanning patches) three (laterally unconfined patches). These configurations produced range flow regimes within canopy, wake interference skimming flow. At low density _{p}\lt0.5$ turbulence canopy increased increasing regardless configuration, while at high _{p}\gt0.5$ relationship between depended on patches. For same density, smaller lateral gaps generated stronger canopy. The relative contributions shear production also varied densities, dominated over production, was more dominant due an enhanced layer top reduced mean velocity A new predictive for channel-averaged turbulent kinetic energy (TKE) developed as function velocity, geometry, which showed good agreement measured TKE.

Язык: Английский

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Green Nourishment: An Innovative Nature-Based Solution for Coastal Erosion

Frontiers in Marine Science, Год журнала: 2022, Номер 8

Опубликована: Фев. 9, 2022

Coastal erosion poses an urgent threat to life and property in low-lying regions. Sand nourishment is increasingly used as a nature-based solution but requires significant natural resources replenishment over time. In this study, novel form of explored that combines shoreface seagrass restoration mitigate coastal (i.e., green nourishment). Using the morphodynamic model Xbeach, impact planting on wave energy dissipation, sediment transport, morphological evolution cross-shore profile was studied for mild conditions intense storm. Model results indicate meadow enhances dissipation provided by nourishment, suggests it may be particularly effective transport mitigation when implemented sheltered nearshore area. The reduced height meadow, rate destruction deposition or above grass after storm event. Green also beach foreshore caused simulated An alternative, more cost-effective technique using seeds explored, which showed similar protection benefits transplants. This modeling study found potentially flooding sandy coasts, future studies are recommended evaluate its morphological, ecological flood risk reduction field.

Язык: Английский

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Velocity, Turbulence, and Sediment Deposition in a Channel Partially Filled With a Phragmites australis Canopy

Water Resources Research, Год журнала: 2022, Номер 58(8)

Опубликована: Авг. 1, 2022

Abstract Laboratory experiments examined the longitudinal evolution of near‐bed velocity, turbulent kinetic energy (TKE), and net deposition in a model Phragmites australis canopy occupying 1/3 channel width. The canopies were constructed from P . with real morphology solid volume fraction between 0.003 0.018. An exponential was modified to predict velocity inside canopy, which TKE can be predicted. By combining predicted probability, we proposed distribution canopy. TKE, good agreement measurements. Relative an upstream reference, within enhanced when two conditions met: in‐canopy, smaller than critical value for resuspension, resuspension took place bare channel. Above vegetation density (defined by ϕ c ), spatially‐averaged surpassed that adjacent provides way estimate always diminished over some flow adjustment distance, L d (distance leading edge fully developed flow). When length greater 0.4 , canopy‐averaged relative Finally, same length, differences plant morphologies did not have strong impact on in‐canopy distribution.

Язык: Английский

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Effects of Submerged Vegetation Arrangement Patterns and Density on Flow Structure

Water, Год журнала: 2023, Номер 15(1), С. 176 - 176

Опубликована: Янв. 1, 2023

Aquatic vegetation appears very often in rivers and floodplains, which significantly affects the flow structure. In this study, experiments have been conducted to investigate effects of submerged arrangement patterns density on Deflected non-bending is arranged square staggered configurations channel bed a large-scale flume. Results showed that configuration leads intensified streamwise velocity, turbulence kinetic energy (TKE), Reynolds shear stress (RSS) compared configuration. When low (λ = 0.04 λ 0.07), produced wake rear more expansive than with high 0.09 0.17) because velocity center four elements lower middle two density. TKE zone deflected indicate maximum root-mean-square fluctuations occur at sheath section (z/H 0.1) top 0.4). behind elements, value RSS occurred slightly above interface between non-vegetation layer, showing Kelvin–Helmholtz instability associated inflectional points longitudinal velocity. Within range study (0.04 < ≈< 0.23), as increases, negative positive values throughout depth increase.

Язык: Английский

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Loss of POC and DOC on seagrass sediments by hydrodynamics

The Science of The Total Environment, Год журнала: 2023, Номер 901, С. 165976 - 165976

Опубликована: Авг. 1, 2023

Coastal development and climate change are sparking growing concern about the vulnerability of organic carbon (OC) stocks in marine sediments to remineralization, especially high threaten coastal ecosystems like seagrass meadows. Uncertainties still exist regarding role played by hydrodynamics, canopies sediment properties OC resuspension remineralization. A set laboratory experiments were conducted assess, for first time, mechanisms which particulate dissolved (POC DOC) may be released remineralized under hydrodynamic conditions (i.e., unidirectional oscillatory flows) two eelgrass densities grain size content). After a gradually increase forces, our results demonstrated that presence reduced erosion loss high-density canopies, while low-density promote (on average, 1.8-fold higher than canopies). We also flows similar DOC from surface 15.5 ± 1.4 18.4 1.8 g m-2, respectively), whereas flow significantly more POC (from 10.8 1.1 32.1 5.6 m-2 flows, respectively). was strongly influenced both meadow structure lower density shoot area) mud water found that, although >74 % upper within 30 days, relatively amount is recalcitrant, highlighting its potential formation blue deposits. This study highlights deposits if degraded and/or yield stronger storms, could potentially weaken meadows' service as ecosystem future.

Язык: Английский

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Turbulence Dictates Bedload Transport in Vegetated Channels Without Dependence on Stem Diameter and Arrangement

Geophysical Research Letters, Год журнала: 2021, Номер 48(21)

Опубликована: Окт. 17, 2021

Abstract Vegetation provides habitat and nature‐based solutions to coastal flooding erosion, drawing significant interest in its restoration, which requires an understanding of sediment transport retention. Laboratory experiments examined the influence stem diameter arrangement on bedload by considering arrays different mixed diameters. Bedload rate was observed depend turbulent kinetic energy, with no dependence diameter, shown be consistent impulse model for entrainment. Existing predictors bare beds, based bed shear stress, were recast terms turbulence. The new turbulence‐based predicted measured canopies across a range conditions drawn from several previous studies. A prediction turbulence biomass velocity also described, providing important step toward predicting real vegetation morphology.

Язык: Английский

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Evolution of flow velocity from the leading edge of 2-D and 3-D submerged canopies

Journal of Fluid Mechanics, Год журнала: 2021, Номер 916

Опубликована: Апрель 14, 2021

Abstract

Язык: Английский

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