Experimentation and Modeling of Reach-Scale Vegetative Flow Resistance due to Willow Patches

Ji, Un; Järvelä, Juha; Västilä, Kaisa; Bae, Inhyeok

doi:10.1061/jhend8.hyeng-13293

Cited by 3 publications

(1 citation statement)

References 65 publications

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“…While the reach-scale water surface slopes differed between experiments to generate different sediment supplies, the patch-scale water surface slope and hydraulics responded similarly over the two hydrographs. This indicates that the flow conditions in and around the vegetation patch were primarily a function of vegetation characteristics rather than reach-scale conditions or bed morphology (e.g., Etminan et al, 2018;Ji et al, 2023;Västilä & Järvelä, 2018), at least at the scale of the morphologic changes observed in this study. In both experiments, streamwise velocity within the vegetation patch was reduced to 60%-75% of that in the freestream owing to increased vegetative roughness, while flow constriction in the adjacent main channel increased the velocity by approximately 5%-20% (Figure 2b), which agreed with previous research on sparse uniform vegetation in open channels (e.g., Caroppi et al, 2022;Kim et al, 2015;Lightbody et al, 2019;Valyrakis et al, 2021).…”

Section: Importance Of Flow-dependent Changes In Velocity and Turbule...mentioning

confidence: 72%

Characterizing Erosion and Deposition in and Around Riparian Vegetation Patches: Complex Flow Hydraulics, Sediment Supply, and Morphodynamic Feedbacks

Tranmer,

Ji,

Ahn

et al. 2024

Water Resources Research

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Riparian vegetation plays a fundamental role in alluvial channel evolution by modifying flow and sedimentation dynamics. To elucidate the roles of sediment supply, flow‐dependent transport capacity, and morphodynamic feedbacks on the evolution of emergent vegetation patches over a single hydrograph, we conducted two experiments with different reach‐scale sediment supplies: a high‐supply experiment (HSE) and low‐supply experiment (LSE). We measured flow velocities, bedload transport, and topographic changes around a full‐scale patch of live emergent willows in an outdoor laboratory flume. Erosion occurred in the patch‐adjacent channel areas irrespective of the sediment supply, whereas deposition within the patch interior was suppressed in the LSE and enhanced in the HSE. The magnitude of patch deposition in each experiment was controlled by the local sediment supply to the patch and local sediment mobility during each discharge in the hydrograph. The local sediment supply was affected by bed morphodynamics at the patch head, which modulated the reach‐scale sediment supply by redistributing the bedload in the channel. Sediment mobility within the patch was flow‐dependent and a function of velocity and turbulent kinetic energy. For different discharges, the velocity in the patch changed proportionally with the freestream velocity; however, the turbulent kinetic energy was more sensitive, being elevated compared with the freestream during high flows and inhibited at low flows. Therefore, deposition and erosion within vegetation patches are not simply functions of the reach‐scale sediment supply or patch flow characteristics, as is often assumed, but additionally depend on the local sediment supply to the patch interior.

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Section: Importance Of Flow-dependent Changes In Velocity and Turbule...mentioning

confidence: 72%

Characterizing Erosion and Deposition in and Around Riparian Vegetation Patches: Complex Flow Hydraulics, Sediment Supply, and Morphodynamic Feedbacks

Tranmer,

Ji,

Ahn

et al. 2024

Water Resources Research

Self Cite

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Blockage effect of emergent riparian vegetation patches on river flow

Bae,

Ji,

Järvelä

et al. 2024

Journal of Hydrology

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Estimating Riparian Vegetation Volume in the River by 3D Point Cloud from UAV Imagery and Alpha Shape

Jang,

Kang

2023

Applied Sciences

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This study employs technology that has many different applications, including flood management, flood level control, and identification of vegetation type by patch size. Recent climate change, characterized by severe droughts and floods, intensifies riparian vegetation growth, demanding accurate environmental data. Traditional methods for analyzing vegetation in rivers involve on-site measurements or estimating the growth phase of the vegetation; however, these methods have limitations. Unmanned aerial vehicles (UAVs) and ground laser scanning, meanwhile, offer cost-effective, versatile solutions. This study uses UAVs to generate 3D riparian vegetation point clouds, employing the alpha shape technique. Performance was evaluated by analyzing the estimated volume results, considering the influence of the alpha radius. Results are most significant with an alpha radius of 0.75. This technology benefits river management by addressing vegetation volume, scale, flood control, and identification of vegetation type.

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Experimentation and Modeling of Reach-Scale Vegetative Flow Resistance due to Willow Patches

Cited by 3 publications

References 65 publications

Characterizing Erosion and Deposition in and Around Riparian Vegetation Patches: Complex Flow Hydraulics, Sediment Supply, and Morphodynamic Feedbacks

Characterizing Erosion and Deposition in and Around Riparian Vegetation Patches: Complex Flow Hydraulics, Sediment Supply, and Morphodynamic Feedbacks

Blockage effect of emergent riparian vegetation patches on river flow

Estimating Riparian Vegetation Volume in the River by 3D Point Cloud from UAV Imagery and Alpha Shape

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