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Статті в журналах з теми "Vegetated channels"

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Автор: Grafiati

Опубліковано: 13 квітня 2023

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1

Zhang, Ming Wu, Chun Bo Jiang, and He Qing Huang. "Lateral Distributions of Depth-Averaged Velocity in Compound Channels with Submerged Vegetated Floodplains." Applied Mechanics and Materials 641-642 (September 2014): 288–99. http://dx.doi.org/10.4028/www.scientific.net/amm.641-642.288.

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Lateral distributions of depth-averaged velocity in open compound channels with submerged vegetated floodplains are analyzed, based on an analytical solution to the depth-integrated Reynolds-Averaged Navier-Stokes equation with a term included to account for the effects of vegetation. The cases of open channels are: rectangular channel with submerged vegetated corner, and compound channel with submerged vegetated floodplain. The present paper proposes a method for predicting lateral distribution of the depth-averaged velocity with submerged vegetated floodplains. The method is based on a two-layer approach where flow above and through the vegetation layer is described separately. An experiment in compound channel with submerged vegetated floodplain is carried out for the present research. The analytical solutions of the three cases are compared with experimental data. The corresponding analytical depth-averaged velocity distributions show good agreement with the experimental data.

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2

Nepf, Heidi M. "Hydrodynamics of vegetated channels." Journal of Hydraulic Research 50, no. 3 (June 2012): 262–79. http://dx.doi.org/10.1080/00221686.2012.696559.

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3

Mohd Yusof, Muhammad Azizol, Suraya Sharil, and Wan Hanna Melini Wan Mohtar. "THE HYDRODYNAMIC CHARACTERISTICS FOR VEGETATIVE CHANNEL WITH GRAVEL BED DUNES." Jurnal Teknologi 84, no. 2 (January 27, 2022): 93–102. http://dx.doi.org/10.11113/jurnalteknologi.v84.17045.

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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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4

Borovkov, V. S., and M. Yurchuk. "Hydraulic resistance of vegetated channels." Hydrotechnical Construction 28, no. 8 (August 1994): 432–38. http://dx.doi.org/10.1007/bf01487449.

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5

Naot, Dan, Iehisa Nezu, and Hiroji Nakagawa. "Unstable Patterns in Partly Vegetated Channels." Journal of Hydraulic Engineering 122, no. 11 (November 1996): 671–73. http://dx.doi.org/10.1061/(asce)0733-9429(1996)122:11(671).

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6

Carollo, F. G., V. Ferro, and D. Termini. "Flow Velocity Measurements in Vegetated Channels." Journal of Hydraulic Engineering 128, no. 7 (July 2002): 664–73. http://dx.doi.org/10.1061/(asce)0733-9429(2002)128:7(664).

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7

Salama, Mohamed M., and Mohamed F. Bakry. "Design of earthen vegetated open channels." Water Resources Management 6, no. 2 (1992): 149–59. http://dx.doi.org/10.1007/bf00872209.

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8

Zhang, Jiao, Zhangyi Mi, Wen Wang, Zhanbin Li, Huilin Wang, Qingjing Wang, Xunle Zhang, and Xinchun Du. "An Analytical Solution to Predict the Distribution of Streamwise Flow Velocity in an Ecological River with Submerged Vegetation." Water 14, no. 21 (November 5, 2022): 3562. http://dx.doi.org/10.3390/w14213562.

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Aquatic submerged vegetation is widespread in rivers. The transverse distribution of flow velocity in rivers is altered because of the vegetation. Based on the vegetation coverage, the cross-section of the ecological channels can be divided into the non-vegetated area and the vegetated area. In the vegetated area, we defined two depth-averaged velocities, which included the water depth-averaged velocity, and the vegetation height-averaged velocity. In this study, we optimized the ratio of these two depth-averaged velocities, and used this velocity ratio in the Navier–Stokes equation to predict the lateral distribution of longitudinal velocity in the open channel that was partially covered by submerged vegetation. Based on the Navier–Stokes equations, the term “vegetation resistance” was introduced in the vegetated area. The equations for the transverse eddy viscosity coefficient ξ, friction coefficient f, drag force coefficient Cd, and porosity α were used for both the non-vegetated area and the vegetated area, and the range of the depth-averaged secondary flow coefficient was investigated. An analytical solution for predicting the transverse distribution of the water depth-averaged streamwise velocity was obtained in channels that were partially covered by submerged vegetation, which was experimentally verified in previous studies. Additionally, the improved ratio proposed here was compared to previous ratios from other studies. Our findings showed that the ratio in this study could perform velocity prediction more effectively in the partially covered vegetated channel, with a maximum average relative error of 4.77%. The improved ratio model reduced the number of parameters, which introduced the diameter of the vegetation, the amount of vegetation per unit area, and the flow depth. This theoretical ratio lays the foundation for analyzing the flow structure of submerged vegetation.

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9

Carollo, Francesco Giuseppe, Vito Ferro, and Donatella Termini. "ANALYSING LONGITUDINAL TURBULENCE INTENSITY IN VEGETATED CHANNELS." Journal of Agricultural Engineering 38, no. 4 (December 31, 2007): 25. http://dx.doi.org/10.4081/jae.2007.4.25.

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10

Naot, Dan, Iehisa Nezu, and Hiroji Nakagawa. "Hydrodynamic Behavior of Partly Vegetated Open Channels." Journal of Hydraulic Engineering 122, no. 11 (November 1996): 625–33. http://dx.doi.org/10.1061/(asce)0733-9429(1996)122:11(625).

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11

Salah Abd Elmoaty, Mohamed, and El-Samman T. A. "Manning roughness coefficient in vegetated open channels." Water Science 34, no. 1 (January 1, 2020): 124–31. http://dx.doi.org/10.1080/11104929.2020.1794706.

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12

Etminan, Vahid, Marco Ghisalberti, and Ryan J. Lowe. "Predicting Bed Shear Stresses in Vegetated Channels." Water Resources Research 54, no. 11 (November 2018): 9187–206. http://dx.doi.org/10.1029/2018wr022811.

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13

Chen, Gang, Wen-xin Huai, Jie Han, and Ming-deng Zhao. "Flow Structure in Partially Vegetated Rectangular Channels." Journal of Hydrodynamics 22, no. 4 (August 2010): 590–97. http://dx.doi.org/10.1016/s1001-6058(09)60092-5.

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14

Folorunso, OP. "Turbulent Kinetic Energy and Budget of Heterogeneous Open Channel with Gravel and Vegetated Beds." Journal of Civil Engineering Research & Technology 3, no. 2 (June 30, 2021): 1–4. http://dx.doi.org/10.47363/jcert/2021(3)115.

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Turbulent kinetic energy (TKE) and budget are indispensable hydraulic parameters to determine turbulent scales and processes resulting from various and different natural hydraulic features in open channels. This paper focuses on experimental investigation of turbulent kinetic energy and budget in a heterogeneous open channel flow with gravel and vegetated beds. Results indicate the turbulent kinetic energy (TKE) value over gravel region of the heterogeneous bed remains approximately constant with flow depth. The highest turbulent kinetic energy was calculated for flexible vegetation arrangement compared to the rigid vegetation. The estimation of the turbulent kinetic energy budget shows the higher values of turbulence production recorded over the flexible vegetated bed, consequently, the dissipation rate exhibits faster decay of turbulence kinetic energy over the vegetated bed in comparison to the gravel bed.

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15

Tang, Xiaonan, D. W. Knight, and M. Sterling. "Analytical model for streamwise velocity in vegetated channels." Proceedings of the Institution of Civil Engineers - Engineering and Computational Mechanics 164, no. 2 (June 2011): 91–102. http://dx.doi.org/10.1680/eacm.2011.164.2.91.

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16

Yang, Kejun, Shuyou Cao, and Donald W. Knight. "Flow Patterns in Compound Channels with Vegetated Floodplains." Journal of Hydraulic Engineering 133, no. 2 (February 2007): 148–59. http://dx.doi.org/10.1061/(asce)0733-9429(2007)133:2(148).

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17

Box, Walter, Kaisa Västilä, and Juha Järvelä. "Transport and deposition of fine sediment in a channel partly covered by flexible vegetation." E3S Web of Conferences 40 (2018): 02016. http://dx.doi.org/10.1051/e3sconf/20184002016.

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Riparian plants exert flow resistance and largely influence the flow structure, which affects erosion, deposition and transport processes of fine sediments. Predicting these vegetative effects is important for flood, sediment and nutrient management. However, predictions on the fate of sediments are complicated by uncertainties associated with the suitable parameterization of natural plants and the associated effects on the turbulent flow field and on the variables in the transport equations. The aim of this study is to quantify deposition and transport of fine sandy sediment in a partly vegetated channel under laboratory conditions. Care was taken to reproduce conditions typical of vegetated floodplain flows including dense flexible grassy understory as a starting point. The experiments were conducted in a flume that is specifically designed to recirculate fine sediment. We measured suspended sediment concentrations with optical turbidity sensors and determined patterns of net deposition over the vegetated parts of the cross section. The flow field was determined with acoustic Doppler velocimetry. Our investigations are intended to improve future predictions of fine sediment storage and transport in natural or constructed vegetated channels, and the first results reported herein were useful in designing further, on-going experiments with complex combinations of vegetation and channel geometry. Key words: sediment transport, suspended sediment, deposition, riparian vegetation, flow field.

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18

Choi, Seongeun, and Jin Hwan Hwang. "Lagrangian Coherent Structure Analysis on the Vegetated Compound Channel with Numerical Simulation." Water 14, no. 3 (January 28, 2022): 406. http://dx.doi.org/10.3390/w14030406.

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Natural channels often consist of a mainstream near their thalwegs and shallow vegetated areas near shores. The compounded and partially vegetated cross-sections play a significantly role in determining the hydrodynamic characteristics of a channel. By employing the Lagrangian Coherent Structure (LCS) analysis, the present work unravels the effect of vegetation and geometry on the hydrodynamic interactions between mainstreams with the various depths and vegetated shallow areas. The LCS method is the concept of dynamical system analyses, which is determined by the finite-time Lyapunov exponents (FTLE) field of fluid particles. It enables to overcome the limitations of using the particle tracking method in cost and time for simulations. Since the LCSs represent material surfaces or asymptotic lines which particles approach, but do not pass through, they match well with the trajectories of particles or materials obtained by solving particle motion equations. Therefore, the temporal and spatial developments of the interfacial layers could be investigated by using the FTLE. As the difference of depth becomes appreciable, the values of FTLE are relatively larger farther from the vegetated area. It implies that the interfacial layer becomes wider with the larger size of vortex produced by the differences of velocities between the mainstreams and the vegetated areas. In other words, as depth differences become large, materials and momentum can be spread from the vegetated area to or collected from a wider area of the mainstream.

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19

McFarlane, S. A., K. L. Gaustad, E. J. Mlawer, C. N. Long, and J. Delamere. "Development of a high spectral resolution surface albedo product for the ARM Southern Great Plains central facility." Atmospheric Measurement Techniques Discussions 4, no. 3 (May 24, 2011): 3097–145. http://dx.doi.org/10.5194/amtd-4-3097-2011.

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Abstract. We present a method for identifying dominant surface type and estimating high spectral resolution surface albedo at the Atmospheric Radiation Measurement (ARM) facility at the Southern Great Plains (SGP) site in Oklahoma for use in radiative transfer calculations. Given a set of 6-channel narrowband visible and near-infrared irradiance measurements from upward and downward looking multi-filter radiometers (MFRs), four different surface types (snow-covered, green vegetation, partial vegetation, non-vegetated) can be identified. A normalized difference vegetation index (NDVI) is used to distinguish between vegetated and non-vegetated surfaces, and a scaled NDVI index is used to estimate the percentage of green vegetation in partially vegetated surfaces. Based on libraries of spectral albedo measurements, a piecewise continuous function is developed to estimate the high spectral resolution surface albedo for each surface type given the MFR albedo values as input. For partially vegetated surfaces, the albedo is estimated as a linear combination of the green vegetation and non-vegetated surface albedo values. The estimated albedo values are evaluated through comparison to high spectral resolution albedo measurements taken during several Intensive Observational Periods (IOPs) and through comparison of the integrated spectral albedo values to observed broadband albedo measurements. The estimated spectral albedo values agree well with observations for the visible wavelengths constrained by the MFR measurements, but have larger biases and variability at longer wavelengths. Additional MFR channels at 1100 nm and/or 1600 nm would help constrain the high resolution spectral albedo in the near infrared region.

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20

McFarlane, S. A., K. L. Gaustad, E. J. Mlawer, C. N. Long, and J. Delamere. "Development of a high spectral resolution surface albedo product for the ARM Southern Great Plains central facility." Atmospheric Measurement Techniques 4, no. 9 (September 1, 2011): 1713–33. http://dx.doi.org/10.5194/amt-4-1713-2011.

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Abstract. We present a method for identifying dominant surface type and estimating high spectral resolution surface albedo at the Atmospheric Radiation Measurement (ARM) facility at the Southern Great Plains (SGP) site in Oklahoma for use in radiative transfer calculations. Given a set of 6-channel narrowband visible and near-infrared irradiance measurements from upward and downward looking multi-filter radiometers (MFRs), four different surface types (snow-covered, green vegetation, partial vegetation, non-vegetated) can be identified. A normalized difference vegetation index (NDVI) is used to distinguish between vegetated and non-vegetated surfaces, and a scaled NDVI index is used to estimate the percentage of green vegetation in partially vegetated surfaces. Based on libraries of spectral albedo measurements, a piecewise continuous function is developed to estimate the high spectral resolution surface albedo for each surface type given the MFR albedo values as input. For partially vegetated surfaces, the albedo is estimated as a linear combination of the green vegetation and non-vegetated surface albedo values. The estimated albedo values are evaluated through comparison to high spectral resolution albedo measurements taken during several Intensive Observational Periods (IOPs) and through comparison of the integrated spectral albedo values to observed broadband albedo measurements. The estimated spectral albedo values agree well with observations for the visible wavelengths constrained by the MFR measurements, but have larger biases and variability at longer wavelengths. Additional MFR channels at 1100 nm and/or 1600 nm would help constrain the high resolution spectral albedo in the near infrared region.

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21

Patil, S., and V. P. Singh. "Dispersion Model for Varying Vertical Shear in Vegetated Channels." Journal of Hydraulic Engineering 137, no. 10 (October 2011): 1293–97. http://dx.doi.org/10.1061/(asce)hy.1943-7900.0000431.

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22

Muhammad, Muhammad Mujahid, Khamaruzaman Wan Yusof, Muhammad Raza Ul Mustafa, Nor Azazi Zakaria, and Aminuddin Ab Ghani. "Prediction models for flow resistance in flexible vegetated channels." International Journal of River Basin Management 16, no. 4 (March 7, 2018): 427–37. http://dx.doi.org/10.1080/15715124.2018.1437740.

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23

Elsiad, A. A. "Flow resistance and flow forces through vegetated open channels." Egyptian Journal for Engineering Sciences and Technology 8, no. 1 (January 1, 2004): 9–10. http://dx.doi.org/10.21608/eijest.2004.96609.

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24

Thornton, Christopher I., Steven R. Abt, Chad E. Morris, and J. Craig Fischenich. "Calculating Shear Stress at Channel-Overbank Interfaces in Straight Channels with Vegetated Floodplains." Journal of Hydraulic Engineering 126, no. 12 (December 2000): 929–36. http://dx.doi.org/10.1061/(asce)0733-9429(2000)126:12(929).

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25

Wang, Yisen, Zhonghua Yang, Mengyang Liu, and Minghui Yu. "Numerical study of flow characteristics in compound meandering channels with vegetated floodplains." Physics of Fluids 34, no. 11 (November 2022): 115107. http://dx.doi.org/10.1063/5.0122089.

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Large eddy simulations were conducted to simulate the flow in compound meandering channels whose main channel sinuosity was 1.381. Then, the floodplain vegetation was generalized using the momentum equation coupled with the drag force formula. The mean flow pattern, secondary flow, coherent structure, turbulence characteristics, and lateral mass and momentum transport with and without floodplain vegetation with relative depths ( Dr) of 0.3–0.5 were studied. Results showed that the floodplain vegetation enabled the flow of the main channel to be more concentrated. The maximum average velocity in the cross section of the main channel increased by 100% and 30% when the relative depth was 0.3 and 0.5. Under the influence of floodplain vegetation, the secondary flow cell transformed greatly with the change in relative depth. When Dr < 0.3, the vegetation caused the vortex center of the secondary flow to move closer to the concave bank side, and the secondary flow distribution presents a flow pattern not flooding the floodplain. When Dr > 0.3, the spatial change in the secondary flow was not obvious. In addition, the floodplain vegetation did not change the large-scale vortex that was separated from the boundary layer of the convex bank side. Meanwhile, the floodplain vegetation increased the overall turbulence intensity, turbulent kinetic energy, and Reynolds stress of the main channel, and it increased the range of lateral mass exchange of the inbank flow and the mean and turbulent transport flux of each cross section.

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26

Wang, Chen, Lennert Schepers, Matthew L. Kirwan, Enrica Belluco, Andrea D'Alpaos, Qiao Wang, Shoujing Yin, and Stijn Temmerman. "Different coastal marsh sites reflect similar topographic conditions under which bare patches and vegetation recovery occur." Earth Surface Dynamics 9, no. 1 (February 11, 2021): 71–88. http://dx.doi.org/10.5194/esurf-9-71-2021.

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Abstract. The presence of bare patches within otherwise vegetated coastal marshes is sometimes considered to be a symptom of marsh dieback and the subsequent loss of important ecosystem services. Here we studied the topographical conditions determining the presence and revegetation of bare patches in three marsh sites with contrasting tidal range, sediment supply, and plant species: the Scheldt estuary (the Netherlands), Venice lagoon (Italy), and Blackwater marshes (Maryland, USA). Based on GIS (geographic information system) analyses of aerial photos and lidar imagery of high resolution (≤2×2 m pixels), we analyzed the topographic conditions under which bare patches occur, including their surface elevation, size, distance from channels, and whether they are connected or not to channels. Our results demonstrate that, for the different marsh sites, bare patches can be connected or unconnected to the channel network and that there is a positive relationship between the width of the connecting channels and the size of the bare patches, in each of the three marsh sites. Further, pixels located in bare patches connected to channels occur most frequently at the lowest elevations and farthest distance from the channels. Pixels in bare patches disconnected from channels occur most frequently at intermediate elevations and distances from channels, and vegetated marshes dominate at highest elevations and shortest distances from channels. In line with previous studies, revegetation in bare patches is observed in only one site with the highest tidal range and highest sediment availability, and it preferentially occurs from the edges of small unconnected bare patches at intermediate elevations and intermediate distances from channels. Although our study is only for three different marsh sites with large variations in local conditions, such as tidal range, sediment availability, and plant species, it suggests that similar topographic conditions determine the occurrence of bare patches. Such insights may inform decision makers on coastal marsh management on where to focus monitoring of early signatures of marsh degradation.

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27

Jang, Chang-Lae. "Experimental Analysis of the Morphological Changes of the Vegetated Channels." Journal of Korea Water Resources Association 46, no. 9 (September 30, 2013): 909–19. http://dx.doi.org/10.3741/jkwra.2013.46.9.909.

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28

Chen, Yen-Chang, Su-Pai Kao, Jen-Yang Lin, and Han-Chung Yang. "Retardance coefficient of vegetated channels estimated by the Froude number." Ecological Engineering 35, no. 7 (July 2009): 1027–35. http://dx.doi.org/10.1016/j.ecoleng.2009.03.002.

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29

Duan, Jennifer G., and Khalid Al-Asadi. "On Bed Form Resistance and Bed Load Transport in Vegetated Channels." Water 14, no. 23 (November 22, 2022): 3794. http://dx.doi.org/10.3390/w14233794.

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A set of laboratory experiments were conducted to study the impact of vegetation on bed form resistance and bed load transport in a mobile bed channel. Vegetation stems were simulated by using arrays of emergent polyvinyl chloride (PVC) rods in several staggered configurations. The total flow resistance was divided into bed, sidewall, and vegetation resistances. Bed resistance was further separated into grain and bed form (i.e., ripples and dunes) resistances. By analyzing experimental data using the downhill simplex method (DSM), we derived new empirical relations for predicting bed form resistance and the bed load transport rate in a vegetated channel. Bed form resistance increases with vegetation concentration, and the bed load transport rate reduces with vegetation concentration. However, these conclusions are obtained by using experimental data from this study as well as others available in the literature for a vegetated channel at low concentration.

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30

Bywater-Reyes, Sharon, Rebecca M. Diehl, and Andrew C. Wilcox. "The influence of a vegetated bar on channel-bend flow dynamics." Earth Surface Dynamics 6, no. 2 (June 14, 2018): 487–503. http://dx.doi.org/10.5194/esurf-6-487-2018.

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Abstract. Point bars influence hydraulics, morphodynamics, and channel geometry in alluvial rivers. Woody riparian vegetation often establishes on point bars and may cause changes in channel-bend hydraulics as a function of vegetation density, morphology, and flow conditions. We used a two-dimensional hydraulic model that accounts for vegetation drag to predict how channel-bend hydraulics are affected by vegetation recruitment on a point bar in a gravel-bed river (Bitterroot River, Montana, United States). The calibrated model shows steep changes in flow hydraulics with vegetation compared to bare-bar conditions for flows greater than bankfull up to a 10-year flow (Q10), with limited additional changes thereafter. Vegetation morphology effects on hydraulics were more pronounced for sparse vegetation compared to dense vegetation. The main effects were (1) reduced flow velocities upstream of the bar, (2) flow steered away from the vegetation patch with up to a 30 % increase in thalweg velocity, and (3) a shift of the high-velocity core of flow toward the cut bank, creating a large cross-stream gradient in streamwise velocity. These modeled results are consistent with a feedback in channels whereby vegetation on point bars steers flow towards the opposite bank, potentially increasing bank erosion at the mid- and downstream ends of the bend while simultaneously increasing rates of bar accretion.

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31

van Maanen, B., G. Coco, and K. R. Bryan. "On the ecogeomorphological feedbacks that control tidal channel network evolution in a sandy mangrove setting." Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 471, no. 2180 (August 2015): 20150115. http://dx.doi.org/10.1098/rspa.2015.0115.

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An ecomorphodynamic model was developed to study how Avicennia marina mangroves influence channel network evolution in sandy tidal embayments. The model accounts for the effects of mangrove trees on tidal flow patterns and sediment dynamics. Mangrove growth is in turn controlled by hydrodynamic conditions. The presence of mangroves was found to enhance the initiation and branching of tidal channels, partly because the extra flow resistance in mangrove forests favours flow concentration, and thus sediment erosion in between vegetated areas. The enhanced branching of channels is also the result of a vegetation-induced increase in erosion threshold. On the other hand, this reduction in bed erodibility, together with the soil expansion driven by organic matter production, reduces the landward expansion of channels. The ongoing accretion in mangrove forests ultimately drives a reduction in tidal prism and an overall retreat of the channel network. During sea-level rise, mangroves can potentially enhance the ability of the soil surface to maintain an elevation within the upper portion of the intertidal zone, while hindering both the branching and headward erosion of the landward expanding channels. The modelling results presented here indicate the critical control exerted by ecogeomorphological interactions in driving landscape evolution.

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32

Hu, Xu Yue, Kun Jiang, Hua Qiang Ren, and Xiao Xiong Shen. "An Experimental Study of the Flow Structures in Vegetated Open Channels." Applied Mechanics and Materials 522-524 (February 2014): 941–49. http://dx.doi.org/10.4028/www.scientific.net/amm.522-524.941.

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To investigate the effects of vegetation on flow Reynolds stress and turbulence intensity,an experiment was performed with plastic rods and artificial waterweeds in a slope-variable laboratory flume; an acoustic Doppler velocimeter was used to measure the instantaneous velocity at different points on the vertical line under different conditions; Turbulence parameters at each measuring point were calculated, such as Reynolds stress and turbulence intensity; The effects of vegetation on flow structures were analyzed through comparison with the turbulence characteristics of uniform open channel flows without vegetation distribution. The experimental results show that the turbulent constant Reynolds stress layer exists in water flows with vegetation distribution compared with the water flows without vegetation distribution. Without vegetation distribution, the viscous shear stress at the flume bed mainly affects the area between the bed and the level at a depth about 30% of the water depth. With vegetation distribution, the effect of the viscous shear stress at the bed weakens.The highest flow turbulence intensity with vegetation distribution occurs within the range of vegetation height.

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33

COUTINHO DE LIMA, ADRIANO, and NORIHIRO IZUMI. "On the initial development of shear layers in partially vegetated channels." Journal of Japan Society of Civil Engineers, Ser. B1 (Hydraulic Engineering) 70, no. 4 (2014): I_61—I_66. http://dx.doi.org/10.2208/jscejhe.70.i_61.

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34

Koftis, Theoharris, and Panayotis Prinos. "Reynolds stress modelling of flow in compound channels with vegetated floodplains." Journal of Applied Water Engineering and Research 6, no. 1 (July 19, 2016): 17–27. http://dx.doi.org/10.1080/23249676.2016.1209437.

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35

Harris, E. L., V. Babovic, and R. A. Falconer. "Velocity predictions in compound channels with vegetated floodplains using genetic programming." International Journal of River Basin Management 1, no. 2 (June 2003): 117–23. http://dx.doi.org/10.1080/15715124.2003.9635198.

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36

Liu, Chao, Yu-qi Shan, Ke-jun Yang, and Xing-nian Liu. "The characteristics of secondary flows in compound channels with vegetated floodplains." Journal of Hydrodynamics 25, no. 3 (June 2013): 422–29. http://dx.doi.org/10.1016/s1001-6058(11)60381-9.

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37

Lima, A. C., and N. Izumi. "On the nonlinear development of shear layers in partially vegetated channels." Physics of Fluids 26, no. 8 (August 2014): 084109. http://dx.doi.org/10.1063/1.4893676.

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38

Gu, Li, Xin-xin Zhao, Ling-hang Xing, Zi-nan Jiao, Zu-lin Hua, and Xiao-dong Liu. "Longitudinal dispersion coefficients of pollutants in compound channels with vegetated floodplains." Journal of Hydrodynamics 31, no. 4 (September 19, 2018): 740–49. http://dx.doi.org/10.1007/s42241-018-0108-4.

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39

Martín-Vide, J. P., P. J. M. Moreta, and S. López-Querol. "Improved 1-D modelling in compound meandering channels with vegetated floodplains." Journal of Hydraulic Research 46, no. 2 (March 2008): 265–76. http://dx.doi.org/10.1080/00221686.2008.9521860.

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40

Caroppi, Gerardo, Paola Gualtieri, Nicola Fontana, and Maurizio Giugni. "Effects of vegetation density on shear layer in partly vegetated channels." Journal of Hydro-environment Research 30 (May 2020): 82–90. http://dx.doi.org/10.1016/j.jher.2020.01.008.

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41

Zen, Simone, and Paolo Perona. "Biomorphodynamics of river banks in vegetated channels with self-formed width." Advances in Water Resources 135 (January 2020): 103488. http://dx.doi.org/10.1016/j.advwatres.2019.103488.

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42

Kiczko, Adam, Kaisa Västilä, Adam Kozioł, Janusz Kubrak, Elżbieta Kubrak, and Marcin Krukowski. "Predicting discharge capacity of vegetated compound channels: uncertainty and identifiability of one-dimensional process-based models." Hydrology and Earth System Sciences 24, no. 8 (August 25, 2020): 4135–67. http://dx.doi.org/10.5194/hess-24-4135-2020.

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Abstract. Despite the development of advanced process-based methods for estimating the discharge capacity of vegetated river channels, most of the practical one-dimensional modeling is based on a relatively simple divided channel method (DCM) with the Manning flow resistance formula. This study is motivated by the need to improve the reliability of modeling in practical applications while acknowledging the limitations on the availability of data on vegetation properties and related parameters required by the process-based methods. We investigate whether the advanced methods can be applied to modeling of vegetated compound channels by identifying the missing characteristics as parameters through the formulation of an inverse problem. Six models of channel discharge capacity are compared in respect of their uncertainty using a probabilistic approach. The model with the lowest estimated uncertainty in explaining differences between computed and observed values is considered the most favorable. Calculations were performed for flume and field settings varying in floodplain vegetation submergence, density, and flexibility, and in hydraulic conditions. The output uncertainty, estimated on the basis of a Bayes approach, was analyzed for a varying number of observation points, demonstrating the significance of the parameter equifinality. The results showed that very reliable predictions with low uncertainties can be obtained for process-based methods with a large number of parameters. The equifinality affects the parameter identification but not the uncertainty of a model. The best performance for sparse, emergent, rigid vegetation was obtained with the Mertens method and for dense, flexible vegetation with a simplified two-layer method, while a generalized two-layer model with a description of the plant flexibility was the most universally applicable to different vegetative conditions. In many cases, the Manning-based DCM performed satisfactorily but could not be reliably extrapolated to higher flows.

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43

Maji, Soumen, Prashanth Hanmaiahgari, Ram Balachandar, Jaan Pu, Ana Ricardo, and Rui Ferreira. "A Review on Hydrodynamics of Free Surface Flows in Emergent Vegetated Channels." Water 12, no. 4 (April 24, 2020): 1218. http://dx.doi.org/10.3390/w12041218.

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This review paper addresses the structure of the mean flow and key turbulence quantities in free-surface flows with emergent vegetation. Emergent vegetation in open channel flow affects turbulence, flow patterns, flow resistance, sediment transport, and morphological changes. The last 15 years have witnessed significant advances in field, laboratory, and numerical investigations of turbulent flows within reaches of different types of emergent vegetation, such as rigid stems, flexible stems, with foliage or without foliage, and combinations of these. The influence of stem diameter, volume fraction, frontal area of stems, staggered and non-staggered arrangements of stems, and arrangement of stems in patches on mean flow and turbulence has been quantified in different research contexts using different instrumentation and numerical strategies. In this paper, a summary of key findings on emergent vegetation flows is offered, with particular emphasis on: (1) vertical structure of flow field, (2) velocity distribution, 2nd order moments, and distribution of turbulent kinetic energy (TKE) in horizontal plane, (3) horizontal structures which includes wake and shear flows and, (4) drag effect of emergent vegetation on the flow. It can be concluded that the drag coefficient of an emergent vegetation patch is proportional to the solid volume fraction and average drag of an individual vegetation stem is a linear function of the stem Reynolds number. The distribution of TKE in a horizontal plane demonstrates that the production of TKE is mostly associated with vortex shedding from individual stems. Production and dissipation of TKE are not in equilibrium, resulting in strong fluxes of TKE directed outward the near wake of each stem. In addition to Kelvin–Helmholtz and von Kármán vortices, the ejections and sweeps have profound influence on sediment dynamics in the emergent vegetated flows.

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44

JAHRA, Fatima, Yoshihisa KAWAHARA, and Fumiaki HASEGAWA. "Performance of a turbulence model for flows in partially vegetated open channels." Journal of Japan Society of Civil Engineers, Ser. B1 (Hydraulic Engineering) 67, no. 4 (2011): I_193—I_198. http://dx.doi.org/10.2208/jscejhe.67.i_193.

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Yang, J. Q., and H. M. Nepf. "A Turbulence‐Based Bed‐Load Transport Model for Bare and Vegetated Channels." Geophysical Research Letters 45, no. 19 (October 4, 2018): 10,428–10,436. http://dx.doi.org/10.1029/2018gl079319.

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46

Tang, XiaoNan, and Donald W. Knight. "Lateral distributions of streamwise velocity in compound channels with partially vegetated floodplains." Science in China Series E: Technological Sciences 52, no. 11 (November 2009): 3357–62. http://dx.doi.org/10.1007/s11431-009-0342-7.

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47

Truong, S. H., W. S. J. Uijttewaal, and M. J. F. Stive. "Exchange Processes Induced by Large Horizontal Coherent Structures in Floodplain Vegetated Channels." Water Resources Research 55, no. 3 (March 2019): 2014–32. http://dx.doi.org/10.1029/2018wr022954.

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48

Yoshioka, Hidekazu, Ayaka Wakazono, Nobuhiko Kinjo, Koichi Unami, and Masayuki Fujihara. "An Extended Mathematical Model for Shallow Water Flows in Vegetated Open Channels." Journal of Rainwater Catchment Systems 20, no. 1 (2014): 29–35. http://dx.doi.org/10.7132/jrcsa.20_1_29.

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49

Liu, Chao, Xing-nian Liu, and Ke-jun Yang. "Predictive model for stage-discharge curve in compound channels with vegetated floodplains." Applied Mathematics and Mechanics 35, no. 12 (October 21, 2014): 1495–508. http://dx.doi.org/10.1007/s10483-014-1884-6.

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50

Pan, Yunwen, Zhijie Li, Kejun Yang, and Dongdong Jia. "Velocity distribution characteristics in meandering compound channels with one-sided vegetated floodplains." Journal of Hydrology 578 (November 2019): 124068. http://dx.doi.org/10.1016/j.jhydrol.2019.124068.

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