The effect of flexible vegetation on flow in drainage channels: Estimation of roughness coefficients at the real scale

Errico, Alessandro; Pasquino, Vittorio; Maxwald, Melanie; Chirico, Giovanni Battista; Solari, Luca; Preti, Federico

doi:10.1016/j.ecoleng.2018.06.018

Cited by 49 publications

(47 citation statements)

References 39 publications

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“…The ADV measurement depths from the water surface have been maintained fixed, regardless of the water level registered under each examined flow rates in the vegetated reclamation channel. Many studies dealing with the interaction between water flow and riparian vegetation have been conducted by employing ADV devices, especially in laboratory flumes [17,18], but just in few cases it has been employed in real manmade channels covered by living riparian vegetation [1,5]. An OTT ® C31 propeller-type universal current meter has been located at the downstream cross section of the experimental reclamation channel stretch (indicated as Section 5 in Figure 2) to monitor the water flow velocity aiming at verifying the continuity of the water flow volume in the experimental channel stretch [1].…”

Section: Measurements Of the Hydrodynamic Characteristicsmentioning

confidence: 99%

“…One of the most challenging tasks when programming the management of riparian vegetation in reclamation channels is the definition of simple and accurate models for assessing the global flow resistance coefficients (e.g., the vegetative Chèzy flow resistance coefficient C r [3,4], the Manning's n hydraulic roughness coefficient [5], the vegetative Darcy-Weisbach's friction factor f" [6]). However, the predictive efficiencies of these models have been rarely evaluated with field experimental data, especially in partly vegetated channels [1,5]. In their study, the authors analyzed the effect of a condition of partial riparian vegetation on flow dynamics and turbulence features related to the presence of both rigid [1] and flexible [5] invasive riparian vegetation.…”

Section: Introductionmentioning

confidence: 99%

“…However, the predictive efficiencies of these models have been rarely evaluated with field experimental data, especially in partly vegetated channels [1,5]. In their study, the authors analyzed the effect of a condition of partial riparian vegetation on flow dynamics and turbulence features related to the presence of both rigid [1] and flexible [5] invasive riparian vegetation.…”

Section: Introductionmentioning

confidence: 99%

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Evaluation of Flow Resistance Models Based on Field Experiments in a Partly Vegetated Reclamation Channel

et al. 2020

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This study presents a methodology for improving the efficiency of Baptist and Stone and Shen models in predicting the global water flow resistance of a reclamation channel partly vegetated by rigid and emergent riparian plants. The results of the two resistance models are compared with the measurements collected during an experimental campaign conducted in a reclamation channel colonized by Common reed (Phragmites australis (Cav.) Trin. ex Steud.). Experimental vegetative Chézy’s flow resistance coefficients have been retrieved from the analysis of instantaneous flow velocity measurements, acquired by means of a downlooking 3-component acoustic Doppler velocimeter (ADV) located at the channel upstream cross section, and by water level measurements obtained through four piezometers distributed along the reclamation channel. The main morphometrical vegetation features (i.e., stem diameters and heights, and bed surface density) have been measured at six cross sections of the vegetated reclamation channel. Following the theoretical assumptions of the divided channel method (DCM), three sub-sections have been delineated in the reference cross section to represent the impact of the partial vegetation cover on the cross sectional variability of the flow field, as observed with the ADV measurements. The global vegetative Chézy’s flow resistance coefficients have been then computed by combining each resistance model with four different composite cross section methods, respectively suggested by Colebatch, Horton, Pavlovskii, and Yen. The comparative analysis between the modeled and the experimental vegetative Chézy’s coefficients has been performed by computing the relative prediction error (εr, expressed in %) under two flow rate regimes. Stone and Shen model combined with the Horton composite cross section method provides vegetative Chézy’s coefficients with the lowest εr.

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Section: Measurements Of the Hydrodynamic Characteristicsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Evaluation of Flow Resistance Models Based on Field Experiments in a Partly Vegetated Reclamation Channel

et al. 2020

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“…Rare are the experiments that deal with solute transport in channels under well‐controlled conditions and unsteady state flow events. In the literature, some studies were carried on real‐scale channels (e.g., Errico et al, ; Newson, ; Rudi, Bailly, Belaud, & Vinatier, ) and on laboratory channels (Vinatier, Bailly, & Belaud, ) for various purposes according to project features: impact of land use change on floods (Jung, Kang, Hong, & Yeo, ), impact of dikes on inundation (Ettema & Muste, ), impact of vegetation on hydraulic resistance (Defina & Peruzzo, ; Errico et al, ), role of flow conditions in hydraulic properties (Rouzes, Moulin, Florens, & Eiff, ) and in biofilm colonization (Coundoul et al, ), and so on. The experiment size should verify hydraulic laws of similitude (Chanson, ).…”

Section: Introductionmentioning

confidence: 99%

“…These laboratories are generally used not only for fundamental research and teaching purposes but also for various applied research projects: river engineering and hydraulic model calibration (see a synthesis in Vidal, ), fluid measurement (Defina & Peruzzo, ; Vinatier et al, ), the hydrology of surface drainage and run‐off (Govers, Takken, Helming, ), flooding and its prevention (Ettema & Muste, ), sediment transport (Iverson, Logan, LaHusen, & Berti, ; Taccone, ), sizing of fish passes (Cassan & Laurens, ; Cassan, Tran, Courret, Laurens, & Dartus, ), river ecosystem management (Errico et al, ; Newson, ; Rudi et al, ), water supply and distribution, irrigation, hydropower, dams studies, and other applications. These experiments enable collecting data under real‐scale conditions and for fully controlled laboratory‐scale conditions where all the terms of water balance are measured.…”

Section: Introductionmentioning

confidence: 99%

A novel platform to evaluate the dampening of water and solute transport in an experimental channel under unsteady flow conditions

Majdalani

Moussa

Chazarin

2020

Hydrological Processes

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This paper presents a novel platform to study the dampening of water and solute transport in an experimental channel under unsteady flow conditions, where literature data are scarce. We address the question about what could be the smallest size of experimental platform that is useful for research, project studies, and teaching activities and that allows to do rational experiments characterized by small space occupation, short experimental duration, high measurement precision, high quality and reproducible experimental curves, low water and energy consumption, and the possibility to test a large variety of hydrograph scenarios. Whereas large scale hydraulic laboratories have focused their studies on sediment transport, our platform deals with solute transport. The objectives of our study are (a) building a platform that allows to do rational experiments, (b) enriching the lack of experimental data concerning water and solute transport under unsteady state conditions, and (c) studying the dampening of water and solute transport. We studied solute transport in a channel with lateral gain and lateral loss under different experimental configurations, and we show how the same lateral loss flow event can lead to different lateral loss mass repartitions under different configurations. In order to characterize water and solute dampening between the input and the output of the channel, we calculate dampening ratios based on peak coordinates of time flow curves and time mass curves and that express the decrease of peak amplitude and the increase of peak occurrence time between the input and output curves. Finally, we use a solute transport model coupling the diffusive wave equation for water transfer and the advection-diffusion equation for solute transport in order to simulate the experimental data. The simulations are quite good with a Nash-Sutcliffe efficiency NSE > 0.98 for water transfer and 0.84 < NSE < 0.97 for solute transport. This platform could serve hydrological modellers because it offers a variety of measured parameters (flow, water height, and solute concentration), at a fine time step under unsteady flow conditions. KEYWORDS diffusive wave equation, solute transport dampening, unsteady flow event, water height measurement, water and solute transport

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Turbulence structure and longitudinal velocity distribution of open channel flows with reedy emergent vegetation

Wang¹,

Liu²,

Feng-yang³

et al. 2021

Ecohydrology

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The vertical distribution of longitudinal velocity and the turbulence structure of open channel flows with natural‐like reedy emergent vegetation were investigated in this study. The natural‐like reedy vegetation consisted of a basal stem and flexible blades with shape and reconfiguration behaviour comparable with those found in actual riparian areas. The 3D velocity field was measured using an acoustic Doppler velocimeter. The vertically non‐uniform distribution of the frontal area could dramatically affect the exchange of mass and momentum between emergent vegetation and their surroundings. The average time velocity profile varied inversely with the frontal area. The high velocity gradient appearing at the middle section of the zone with frontal area varied considerably. The structures of vortices and vertical transport were analysed using spectral analysis and conditional sampling to identify the prominent vortical structures and their contribution to momentum transport. Spectral analysis suggested that the stem‐scale vortices set by stem spacing where the vertical frontal area had no clear change were dominant, and shear‐layer vortices where vertical frontal area dramatically changed cannot be disregarded. Quadrant analysis showed that inward and outward interactions were the dominant contributors to Reynolds stress, excluding the zones approaching the channel boundary and the vertical frontal area that dramatically changed. A four‐layer model was developed to predict the vertical distribution of longitudinal velocity with a newly established profile of local drag coefficient. The predicting results agreed well with the experimental data.

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The effect of flexible vegetation on flow in drainage channels: Estimation of roughness coefficients at the real scale

Cited by 49 publications

References 39 publications

Evaluation of Flow Resistance Models Based on Field Experiments in a Partly Vegetated Reclamation Channel

Evaluation of Flow Resistance Models Based on Field Experiments in a Partly Vegetated Reclamation Channel

A novel platform to evaluate the dampening of water and solute transport in an experimental channel under unsteady flow conditions

Turbulence structure and longitudinal velocity distribution of open channel flows with reedy emergent vegetation

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