Impacts of vegetation over bedforms on flow characteristics in gravel-bed rivers

Afzalimehr, Hossein; Maddahi, Mohammad Reza; Sui, Jueyi; Rahimpour, Majid

doi:10.1007/s42241-019-0053-x

Cited by 19 publications

(13 citation statements)

References 31 publications

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“…The second crest has notably higher values where sshape is noticeably formed. Study by Afzalimehr et al [2] informs the variations in velocity over vegetative covered gravel bedform are far greater than those over a gravel bedform without vegetation. Illustrating the effect of vegetation on the boundary layer's outer zone.…”

Section: Resultsmentioning

confidence: 99%

“…This might be due to the rough bed dunes surface by 2 mm which have more irregular shape and produce wake vortices. This activity might consider erosion happened during the experiment [2] At 6 о angles, turbulence intensity is substantial at the brink and lee ward as these locations where the wakes begin to develop and lose. It is observed at depth z/d<3, the turning point of the turbulence intensity decreasing as upward directions.…”

Section: Resultsmentioning

confidence: 99%

“…The presence of both vegetation and low angle dunes might produce differ explanations. As study carried out by Afzalimehr et al [2] on the field, the formation of a new boundary layer is caused by a transition in bed roughness from non-vegetative gravel bed to gravel bed with vegetation. The velocity profiles over vegetated and non-vegetated bedforms vary because of this new boundary layer.…”

Section: Introductionmentioning

confidence: 97%

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The Hydrodynamic Characteristics for Vegetative Channel With Gravel Bed Dunes

2022

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Aquatic plants are known to provide flow resistance and impact the turbulence intensity and turbulent kinetic energy within the vegetated area. This paper further investigates the impact of both vegetation and dunes in open channels to the hydrodynamic characteristic of flow. Emergent vegetations were built from rigid wooden rod in staggered arrangement with 0.5% vegetations density were applied in the flume. Experiments were conducted with flow rate of 0.0058 m3/s throughout the experiments. Dunes were constructed from gravel of 2 mm size diameter in the shape of standing waves of three different lee slope angles of 3⁰, 6⁰ and 9⁰. Flow velocities are measured by using a velocimeter to get the raw data for the three-dimensional flow velocity in the x, y, and z directions. The velocities data were then analysed to calculate the mean velocity, turbulence intensity and turbulent kinetic energy. Experimental results showed that, for all three lee slope angles presented higher flow velocity in the vegetated channel compared to the non-vegetated channel. It was also found that greater lee slope angle dunes generate higher velocity for both channels with and without vegetation. Higher turbulence intensity can be found near the bed area and greater turbulence intensity also shown in the positive slope of a dunes compared to negative slope area. Higher turbulent kinetic energy values were recorded within the vegetated channel compared to the non-vegetated channels.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 97%

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The Hydrodynamic Characteristics for Vegetative Channel With Gravel Bed Dunes

2022

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“…However, flow structures become even more complex when vegetation appears in channels with bedforms [38]. How the existence of vegetation changes flow pattern over gravel bedforms still remains poorly understood and could be considered as another potential development of the present research work.…”

Section: New Research Prospectsmentioning

confidence: 96%

Anisotropy in the Free Stream Region of Turbulent Flows through Emergent Rigid Vegetation on Rough Beds

Penna

Coscarella

D’Ippolito

et al. 2020

Water

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Most of the existing works on vegetated flows are based on experimental tests in smooth channel beds with staggered-arranged rigid/flexible vegetation stems. Actually, a riverbed is characterized by other roughness elements, i.e., sediments, which have important implications on the development of the turbulence structures, especially in the near-bed flow zone. Thus, the aim of this experimental study was to explore for the first time the turbulence anisotropy of flows through emergent rigid vegetation on rough beds, using the so-called anisotropy invariant maps (AIMs). Toward this end, an experimental investigation, based on Acoustic Doppler Velocimeter (ADV) measures, was performed in a laboratory flume and consisted of three runs with different bed sediment size. In order to comprehend the mean flow conditions, the present study firstly analyzed and discussed the time-averaged velocity, the Reynolds shear stresses, the viscous stresses, and the vorticity fields in the free stream region. The analysis of the AIMs showed that the combined effect of vegetation and bed roughness causes the evolution of the turbulence from the quasi-three-dimensional isotropy to axisymmetric anisotropy approaching the bed surface. This confirms that, as the effects of the bed roughness diminish, the turbulence tends to an isotropic state. This behavior is more evident for the run with the lowest bed sediment diameter. Furthermore, it was revealed that also the topographical configuration of the bed surface has a strong impact on the turbulent characteristics of the flow.

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“…The presence of roughness factors such as streambed vegetation and gravel bed (generally in mountain streams) affect flow velocities, shear stress, and turbulence intensities. For example, streambed anisotropy enhanced by vegetation generates strong secondary currents and develops a new boundary layer by changing bed roughness from gravel bed to vegetated bed [39]. Ignoring these factors or imprecise estimation/identification of roughness factors develop uncertainties in hydraulic processes.…”

Section: Bed Shear Stress and Bed Roughnessmentioning

confidence: 99%

Upscaling of Surface Water and Groundwater Interactions in Hyporheic Zone from Local to Regional Scale

Akhtar

Syakir

Ahmad

et al. 2022

Water

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The groundwater (GW) and surface water (SW) interaction (SW-GW) through the hyporheic zone is a significant component in sustainable water resource management. The complexities in SW-GW interactions increase from a local to a regional scale and are affected by variation in hydraulic, hydrologic, and hydrogeologic (3H) processes. Controlling factors and their upscaling of these processes to assess SW-GW interaction have not been addressed sufficiently in previous studies. Additionally, it is unclear what the effective factors are at different scales during the upscaling. Therefore, the present review focused on controlling factors of 3H processes in SW-GW interaction and their upscaling techniques. Relevancy of controlling factors was identified at different scales. Applications of different approaches and their uncertainties were also discussed for the characterization of SW-GW interactions. The study revealed that the improved data from different approaches is crucial for machine learning training and its application in the SW and GW assessment at local, sub-catchment, and catchment scales. Based on the outcomes, a framework has been proposed to execute modalities of controlling factors using remote sensing, geophysics, and artificial intelligence. The proposed framework could help in handling big data and accurate upscaling for water resource management.

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Impacts of vegetation over bedforms on flow characteristics in gravel-bed rivers

Cited by 19 publications

References 31 publications

The Hydrodynamic Characteristics for Vegetative Channel With Gravel Bed Dunes

The Hydrodynamic Characteristics for Vegetative Channel With Gravel Bed Dunes

Anisotropy in the Free Stream Region of Turbulent Flows through Emergent Rigid Vegetation on Rough Beds

Upscaling of Surface Water and Groundwater Interactions in Hyporheic Zone from Local to Regional Scale

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