Experimental Observations of Floodplain Vegetation, Bedforms, and Sediment Transport Interactions in a Meandering Channel

White, Daniel C.; Morrison, Ryan R.; Nelson, Peter A.

doi:10.1029/2023jf007136

Cited by 4 publications

(1 citation statement)

References 102 publications

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“…Revealed the flow velocity distribution characteristics under the influence of flexible vegetation and the resistance characteristics of the vegetation riverbed. White et al [23] found that higher-density vegetation and greater flow can increase the heterogeneity of bed terrain. These findings indicate that vegetation and natural hydrological conditions, including floodplain water flow, can enhance the complexity of river habitats.…”

Section: Introductionmentioning

confidence: 99%

Investigation of the Influence of Reed Vegetation on the Hydraulic Characteristics of the Huai River Inflow Channel

Zhang,

Cheng,

Zhang

et al. 2024

Water

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When there is vegetation on the beach or main channel bed, it will have a significant impact on the river channel. This study was based on physical model experiments to investigate the flow conditions of the Jinhu section of the Huaihe River estuary, revealing the influence of reed vegetation on water flow resistance. A new comprehensive roughness formula was proposed, and the predictive effectiveness of the formula was verified. The theoretical results indicate that under the condition of vegetation not being submerged, the comprehensive roughness is directly proportional to the square root of vegetation density in areas with vegetation coverage, the square root of water surface vegetation coverage, and the 2/3 power of the hydraulic radius. The bottom slope does not affect it. Under the condition of vegetation inundation, the comprehensive roughness is smaller than that under the condition of no inundation. The experimental prediction results of the influence of reeds on roughness indicate that the measured roughness values and theoretical roughness calculation values are in good agreement. Under the same operating conditions, the roughness gradually decreases with an increase in flow rate. Under the full-reed working condition, the calculated roughness value and the measured roughness value have the same trend of change, both decreasing with the increase in flow rate. The experimental prediction results of the influence of reeds on the relationship between water level and flow rate show that the roughness value of 0 increases with the increase in reed grass surface coverage rate Ki, and an increase in Ki can lead to an increase in comprehensive roughness.

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Section: Introductionmentioning

confidence: 99%

Investigation of the Influence of Reed Vegetation on the Hydraulic Characteristics of the Huai River Inflow Channel

Zhang,

Cheng,

Zhang

et al. 2024

Water

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How Emergent Vegetation Patch Shapes Affect Flow Structure in Open Channel Environments

Anjum,

Pasha,

Ashraf

et al. 2024

Ecohydrology

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Vegetation patches, which naturally occur in a variety of patterns, have an impact on the flow dynamics and geometry of rivers. There have been prior studies on vegetation patches, but none have examined the impact of differently shaped vegetation patch, i.e., circle, square and rectangle, and the comparison of these varying patch shapes from an ecological point of view. Hence, a computational fluid dynamics (CFD) technique using FLUENT has been employed in the present research to evaluate the flow dynamics and turbulence characteristics around emergent vegetation patches of various forms in an open channel. The results show that the shape of vegetation patches had a significant impact on the approaching flow, with circular patch offering the highest flow resistance among all other configurations. Flow shedding behaviour behind the patch was also prominent in the case of circular patch shape with a formation of large Kármán vortex street with vortex sizes up to 1.5 times the patch diameter. In the downstream region of vegetation patch, a reduction of 25%–30% in the mean streamwise velocity was observed for circular patch, whereas a 15% decrease was observed for rectangular and square patches. The outcomes of this study found that flow turbulence and stability in the open channel are significantly influenced by vegetation patch shape. This research reveals that the shape of vegetation patches, particularly circular configuration, significantly influences flow dynamics, thereby enhancing habitat complexity in riverine ecosystems. These findings are vital for developing informed river restoration and management strategies that support biodiversity and promote ecological resilience.

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Morphological response of gravel bed rivers near a knickpoint: Effect of bars on dynamic equilibrium river profile

Tanabe,

Iwasaki,

Shimizu

2024

Earth Surf Processes Landf

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Geomorphological evolution is one of the main factors that increases flood damage in small or medium rivers located in upstream river reaches. These types of flood damage have been increasing at knickpoints where the riverbed slope and river width change abruptly and are likely to cause non‐equilibrium conditions for sediment transport during floods. Therefore, it is important to understand the non‐equilibrium morphological response at the knickpoint and the resulting new dynamic equilibrium state under given external forces. The effects of two‐dimensional (2D) morphological features on the dynamic equilibrium riverbed profile, however, have not been specifically studied because the methods currently in use for calculating equilibrium profiles are based on zero‐ or one‐dimensional (0D or 1D) modeling. Here, we perform numerical calculations using the 2D morphodynamic model iRIC‐Nays2DH to clarify the dynamic equilibrium profile and the process of reaching a dynamic equilibrium state. We also use an existing 1D model to show the 2D effect in the dynamic equilibrium state. To understand this, we set up three channels: slope transition point, width transition point, and both the slope and width transition point. 1D results show a constant slope profile in channels with constant width and upward‐convex profiles in channels with width expansion at the equilibrium state, owing to the adjustment of the difference in sediment transport volume in the two reaches with different widths by changing the slopes. In contrast, the 2D results show that the alternate bars create a small autogenic knickpoint even in the straight channel and significantly dampen sediment deposition at the width expansion point, as seen in the 1D model result. This was because the bars' shape increased the volume of sediment transport because the shape of the bars concentrated flow. These results suggest that 2D morphological features, such as fluvial bars, play a significant role in the equilibrium riverbed profile.

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Experimental Observations of Floodplain Vegetation, Bedforms, and Sediment Transport Interactions in a Meandering Channel

Cited by 4 publications

References 102 publications

Investigation of the Influence of Reed Vegetation on the Hydraulic Characteristics of the Huai River Inflow Channel

Investigation of the Influence of Reed Vegetation on the Hydraulic Characteristics of the Huai River Inflow Channel

How Emergent Vegetation Patch Shapes Affect Flow Structure in Open Channel Environments

Morphological response of gravel bed rivers near a knickpoint: Effect of bars on dynamic equilibrium river profile

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