Interaction between flow, transport and vegetation spatial structure

Luhar, Mitul; Rominger, Jeffrey Tsaros; Nepf, Heidi

doi:10.1007/s10652-008-9080-9

Cited by 242 publications

(260 citation statements)

References 73 publications

(104 reference statements)

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“…9) are similar to s when s/k ≪ 1, and proportional to k when s/k > 0.15 which yields to equation (11). Equation (11) is consistent with literature for shallow cases (Coceal and Belcher, 2004;Nikora et al, 2013) or for deep cases (Ghisalberti and Nepf, 2006;Luhar et al, 2008;Huai et al, 2009;Poggi et al, 2009). For all experiments considered, the averaged error between the experimental and computed (with equation (11)) discharge is about 20% as indicated by the dashlines in Figure 9b.…”

Section: Submerged Conditionssupporting

confidence: 88%

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Design of emergent and submerged rock-ramp fish passes

Cassan

Laurens

2016

Knowl. Manag. Aquat. Ecosyst.

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-An analytical model is developed to calculate the stage-discharge relationship for emergent and submerged rock-ramp fish passes. A previous model has been modified and simplified to be adapted to a larger range of block arrangement. For submerged flows, a two-layer model developed for aquatic canopies is used. A turbulent length scale is proposed to close the turbulence model thanks to a large quantity of data for fully rough flows from the literature and experiments. This length scale depends only on the characteristic lengths of arrangements of obstacles. Then the coefficients of the logarithmic law above the canopy can also be deduced from the model. As a consequence, the total discharge through the fish pass is computed by integrating the vertical velocity profiles. A good fit is found between the model and commonly observed values for fish pass or a vegetated canopy. The discharge of the fish pass is then accurately estimated for a large range of hydraulic conditions, which could be useful for estimating fish passability through the structure.

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Section: Submerged Conditionssupporting

confidence: 88%

“…The l 0 value can be expressed experimentally using several approaches (Huthoff et al, 2007;Konings et al, 2012;Luhar et al, 2008;Nepf, 2012;Poggi et al, 2009). The present approach is a combination of these formulas in order to use a formula available for a large range of macro-roughness arrangement.…”

Section: Submerged Conditionsmentioning

confidence: 99%

Design of emergent and submerged rock-ramp fish passes

Cassan

Laurens

2016

Knowl. Manag. Aquat. Ecosyst.

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“…This corresponds to a dense canopy (ah > 0.1) for which turbulent sweeps are not expected to penetrate through the entire height of the canopy. 10,45 For comparison, we also considered a completely rigid model canopy with comparable roughness density, h = 13.8 cm, a = 8 m −1 , and ah = 1.1 (run R8 in Ghisalberti and Nepf 14 ).…”

Section: A Experimental Designmentioning

confidence: 99%

“…In addition, the penetration of turbulence through the canopy to the bed determines the likelihood of sediment resuspension, an important feedback to vegetation health. 10,11 Specifically, resuspension negatively impacts light availability for photosynthesis and associated erosion may destabilize shoots. Dense canopies that reduce near-bed turbulence can enhance the supply of nutrients to the plants by promoting the retention of nutrient-rich fine sediment and organic matter.…”

Section: Introductionmentioning

confidence: 99%

Strong and weak, unsteady reconfiguration and its impact on turbulence structure within plant canopies

et al. 2014

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Numerical evaluation of tree canopy shape near noise barriers to improve downwind shielding J. Acoust. Soc. Am. 123, 648 (2008); 10.1121/1.2828052 This article is copyrighted as indicated in the article. Reuse of AIP content is subject to the terms at: http://scitation. Flexible terrestrial and aquatic plants bend in response to fluid motion and this reconfiguration mechanism reduces drag forces, which protects against uprooting or breaking under high winds and currents. The impact of reconfiguration on the flow can be described quantitatively by introducing a drag coefficient that decreases as a power-law function of velocity with a negative exponent known as the Vogel number. In this paper, two case studies are conducted to examine the connection between reconfiguration and turbulence dynamics within a canopy. First, a flume experiment was conducted with a model seagrass meadow. As the flow rate increased, both the mean and unsteady one-dimensional linear elastic reconfiguration increased. In the transition between the asymptotic regimes of negligible and strong reconfiguration, there is a regime of weak reconfiguration, in which the Vogel number achieved its peak negative value. Second, large-eddy simulation was conducted for a maize canopy, with different modes of reconfiguration characterized by increasingly negative values of the Vogel number. Even though the mean vertical momentum flux was constrained by field measurements, changing the mode of reconfiguration altered the distribution, strength, and fraction of momentum carried by strong and weak events. Despite the differences between these two studies, similar effects of the Vogel number on turbulence dynamics were demonstrated. In particular, a more negative Vogel number leads to a more positive peak of the skewness of streamwise velocity within the canopy, which indicates a preferential penetration of strong events into a vegetation canopy. We consider different reconfiguration geometry (one-and two-dimensional) and regime (negligible, weak, and strong) that can apply to a wide range of terrestrial and aquatic canopies. C 2014 AIP Publishing LLC.

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“…Nehal et al (2005) suggested that overall flow resistance is significantly influenced by the pattern of distribution of the plants. Luhar et al (2008) showed that plant impacts water flow and transport and flow feedbacks influence plant spatial structure. Ye et al (2015) found that plant distribution patterns impact the effects of overland flow resistance.…”

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confidence: 99%

Simulation study of anisotropic flow resistance of farmland vegetation

Zhang¹,

Yin²,

Zhang³

et al. 2017

Soil & Water Res.

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Farmland vegetation is commonly cultivated with uniform planting spacing and heights. The effect of these features on resistance to hydraulic erosion is unclear. Hydraulic model experiments with the angle between the crop rows and the water flow direction set at 15°, 30°, 45° or 90° were conducted to analyze variation in the law of water flow resistance under partial or complete submergence of the crop. Cultivation can impact the flow resistance on slopes and this effect was greater when the crop was partially submerged. When planting spacing, slope, and water depth were constant, the change of the water flow Darcy-Weisbach resistance coefficient f with crop row-water flow angle was f 15° > f 30° > f 45° > f 90°. This suggests that flow resistance of farmland vegetation is anisotropic. The water flow resistance coefficient of crops that were partly submerged increased with water depth, but decreased with water depth when the crop was completely submerged. At the critical change from partial submergence to complete submergence, the water flow resistance coefficient was the highest when water depth was equal to crop height. These results may be useful for optimizing farmland planting and soil and water conservation.

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Interaction between flow, transport and vegetation spatial structure

Cited by 242 publications

References 73 publications

Design of emergent and submerged rock-ramp fish passes

Design of emergent and submerged rock-ramp fish passes

Strong and weak, unsteady reconfiguration and its impact on turbulence structure within plant canopies

Simulation study of anisotropic flow resistance of farmland vegetation

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