A Study of Drag Coefficient Related with Vegetation Based on the Flume Experiment

Er-qing, Hui; Xinge, Hu; Jiang, Chunbo; Ma, Fei; Zhu, Zhenduo

doi:10.1016/s1001-6058(09)60062-7

Cited by 46 publications

(20 citation statements)

References 12 publications

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“…The specific transportation needs that directed the project were to characterize the hydraulic roughness of flood plains for bridge design and environmental impact analysis. Recent studies have confirmed the importance of rigid, unsubmerged vegetation in determining flow depths and velocities in shallow flow situations such as commonly encountered in wide flood plains [1][2][3][4]. The studies highlight the importance of stand density (ratio of obstructed area to total area) and trunk diameter.…”

Section: Introductionmentioning

confidence: 75%

Characterization of Forested Landscapes from Remotely Sensed Data Using Fractals and Spatial Autocorrelation

Al‐Hamdan

Cruise

Rickman

et al. 2012

Advances in Civil Engineering

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The characterization of forested landscapes is frequently required in civil engineering practice. In this study, some spatial analysis techniques are presented that might be employed with Landsat TM data to analyze forest structure characteristics. A case study is presented wherein fractal dimensions (FDs), along with a simple spatial autocorrelation technique (Moran’sI), were related to stand density parameters of the Oakmulgee National Forest located in the southeastern United States (Alabama). The results indicate that when smaller trees do not dominate the landscape (<50%), forested areas can be differentiated according to breast sizes and thus important flood plain characteristics such as ratio of obstructed area to total area can be estimated from remotely sensed data using the studied indices. This would facilitate the estimation of hydraulic roughness coefficients for computation of flood profiles needed for bridge design. FD and Moran’sIremained fairly constant around the values of 2.7 and 0.9 (resp.) for samples with either greater than 50% saplings or less than 50% sawtimber and with ranges of 2.7–2.9 and 0.6–0.9 as the saplings decreased or the sawtimber increased. Those indices can also distinguish hardwood and softwood species facilitating forested landscapes mapping for preliminary environmental impact analysis.

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Section: Introductionmentioning

confidence: 75%

Characterization of Forested Landscapes from Remotely Sensed Data Using Fractals and Spatial Autocorrelation

Al‐Hamdan

Cruise

Rickman

et al. 2012

Advances in Civil Engineering

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“…Compared to the underlying land surfaces of other tall vegetation and forest types, the momentum bulk transfer coefficient C d over the banana plantation surface was greater, at 10 −2 , by a whole order. The high C d values over the banana plantation may also be due to airflow through and around the plants, which is largely related to vegetation density, plant diameter, leaf size, and plant types in the community, as well as to hydrodynamic conditions (Tanino and Nepf 2008;Hui et al 2010;Cheng and Nguyen 2011). According to the Monin-Obukhov theory, the integral turbulence characteristics for wind velocity, temperature, and humidity should relate to stability parameters, as follows:…”

Section: Turbulence Transfer Coefficients For Momentum and Sensible Hmentioning

confidence: 99%

A comparison between energy transfer and atmospheric turbulent exchanges over alpine meadow and banana plantation

Ding

Wen³

et al. 2016

Theor Appl Climatol

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Banana plantation and alpine meadow ecosystems in southern China and the Tibetan Plateau (TP) are unique in the underlying surfaces they exhibit. In this study, we used eddy covariance and a micrometeorological tower to examine the characteristics of land surface energy exchanges over a banana plantation in southern China and an alpine meadow in the Tibetan Plateau from May 2010 to August 2012. The results showed that the diurnal and seasonal variations in upward shortwave radiation flux and surface soil heat flux were larger over the alpine meadow than over the banana plantation surface. Dominant energy partitioning varied with season. Latent heat flux was the main consumer of net radiation flux in the growing season, whereas sensible heat flux was the main consumer during other periods. The Monin-Obukhov similarity theory was employed for comparative purposes, using sonic anemometer observations of flow over the surfaces of banana plantations in the humid southern China monsoon region and the semi-arid areas of the TP, and was found to be applicable. Over banana plantation and alpine meadow areas, the average surface albedo and surface aerodynamic roughness lengths under neutral atmospheric conditions were ∼0.128 and 0.47 m, and ∼0.223 and 0.01 m, respectively. During the measuring period, the mean annual bulk transfer coefficients for momentum and sensible heat were 1.47 × 10 −2 and 7.13 × 10 −3 , and 2.91 × 10 −3 and 1.96 × 10 −3 , for banana plantation and alpine meadow areas, respectively.

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“…Moreover, Sand-Jensen [38] suggested that drag, which is caused by flexible, submerged macrophytes, may increase in direct proportion to water velocity, whereas in the vicinity of rigid vegetation, the flow resistance increases proportionally, at least, to the square root of velocity. Although there have been many attempts to model the interactions between plants and turbulent flow in a laboratory, e.g., [41][42][43][44][45], similar experiments in the field are not common, e.g., [6]. Thus, the transfer of laboratory knowledge to real conditions is a challenge that needs to be addressed.…”

Section: Introductionmentioning

confidence: 99%

On the Relationship between Aquatic Plant Stem Characteristics and Drag Force: Is a Modeling Application Possible?

Łoboda

Karpiński

Bialik

2018

Water

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This paper presents a basic model that shows the relationship between the diameter of a stem and its flexural rigidity. The model was developed from experimental measurements of biomechanical traits (i.e., tensile and bending traits like maximum forces, stresses, moduli of elasticity, flexural rigidity, strain) of three freshwater macrophyte species (Elodea canadensis Michx., Potamogeton pectinatus L., and P. crispus L.), reflecting the seasonal changes in plant biomechanics throughout the vegetative season. These were obtained with the use of a bench-top testing machine in 2016 and 2017. The presented calculations are based on the ratio of drag-to-bending forces, in which the flexural rigidity plays a key role. The proposed model has the form EI = ad b , and two approaches based on a regression analysis were applied to determine the parameters of the model-a and b. In the first method, the parameters were identified separately for each day of measurement, while in the second method, the coefficient b was calculated for all data from all days as a unified number for individual plants. The results suggest that coefficient b may provide information about the proportion of changes in drag forces depending on plant stiffness. The values of this coefficient were associated with the shape of the stem cross-section. The more circular the cross-section, the closer the value of the parameter was to 1. The parameter values were 1.60 for E. canadensis, 1.98 for P. pectinatus, and 2.46 for P. crispus. Moreover, this value also depended on the density of the cross-section structure. Most of the results showed that with an increase in stem diameter, the ratio between the drag and bending forces decreased, which led to fewer differences between these two forces. The model application may be introduced in many laboratory measurements of flow-biota interactions as well as in aquatic plant management applications. The implementation of these results in control methods for hydrophytes may help in mitigating floods caused by increases to a river channel's resistance due to the occurrence of plants.

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A Study of Drag Coefficient Related with Vegetation Based on the Flume Experiment

Cited by 46 publications

References 12 publications

Characterization of Forested Landscapes from Remotely Sensed Data Using Fractals and Spatial Autocorrelation

Characterization of Forested Landscapes from Remotely Sensed Data Using Fractals and Spatial Autocorrelation

A comparison between energy transfer and atmospheric turbulent exchanges over alpine meadow and banana plantation

On the Relationship between Aquatic Plant Stem Characteristics and Drag Force: Is a Modeling Application Possible?

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