Dissertations / Theses on the topic 'Vegetated channels'

Laboratory experiments concerning stage-discharge, flow resistance, bedforms, sediment transport and flow structures have been carried out in a meandering channel with simulated non-vegetated and vegetated floodplains for overbank flow. The effect of placing solid blocks in different arrangements as a model of rigid, unsubmerged floodplain vegetation on a floodplain adjacent to a meandering channel is considered. The aim was to investigate how density and arrangements of floodplain vegetation influence stage-discharge, flow resistance, sediment transport and flow behaviours. Stage-discharge curves, Manning's n and drag force FD are determined over 165 test runs. The results from the laboratory model tests show that the placing of solid blocks along some part of the bend sections has a significant effect on stage-discharge characteristics. The change in stage-discharge by the blocks is compared using different arrangements, including the non-vegetated floodplains case. The experimental results show that the presence of energy losses due to momentum exchange between the main channel and the floodplain as well as the different densities of the blocks on a floodplain induce additional flow resistance to the main channel flow, particularly for shallow overbank flows. In general, the results show that the density and arrangement of blocks on the floodplains are very important for stage-discharge determination and, in some cases, for sediment transport rates, especially for a mobile main channel. Also, the correction parameter, a is introduced in order to understand the effects of blocks and bedforms on the force balance equation. By applied the correction factor c; a stagedischarge rating curve can be estimated when the avalue is calibrated well. Telemac 2D and 3D were applied to predict mean velocity, secondary flow and turbulent kinetic energy. Telemac computations for non-vegetated and vegetated floodplain cases in a meandering channel generally give reasonably good predictions when compared with the measured data for both velocity and boundary shear stress in the main channel. Detailed analyses of the. predicted flow variables were therefore carried out in order to understand mean flow mechanisms and secondary flow structures in compound meandering channels. The non-vegetated and two different cases of vegetated floodplain for different relative depths were considered. For the arrangement on a non-vegetated floodplain shows how the shearing of the main channel flow as the floodplain flow plunges into and over the main channel influences the mean and turbulent flow structures, particularly in the cross-over region. While applying vegetated floodplain along a cross-over section confirmed that the minimum/reduction shearing of the main channel flow by the floodplain flow plunging into and over the main channel is observed from the cross-sectional distributions of the streamwise velocity (U), lateral velocity (V), and secondary flow vectors. In addition to that, the vegetated floödplain along the apex bend region shows a small velocity gradient within the bend apex region. However, strong secondary flow in the cross-over section suggested that the flow interaction was quite similar to the non vegetation case in the cross-over section region.

Vegetation in rivers increases flow resistance and bank stability, reduces bed resistance and flow conveyance, improves water quality, promotes habitat diversity, and alters both mean and turbulent flow. By reducing bed resistance and altering turbulent characteristics, vegetation can change the distribution of deposition and erosion processes. To understand all above mentioned vegetation effects, more research is needed. The goal of this dissertation was to determine the impacts of vegetation on bed resistance and sediment transport and identify a best approach for quantifying vegetation induced friction resistance. To achieve this, both experimental study and numerical simulation were performed. A series of laboratory experiments were conducted in an open channel flume to investigate the impacts of vegetation density on bed resistance and bed load transport for emergent vegetation condition. The bed resistance in a mobile bed channel is equal to the summation of grain and bed form resistances. An attempt has been made to make a separation between grain and bed form resistances, which is challenging and has never been reported in literature. An alternative approach is used to calculate the grain resistance. A new iterative method was derived to calculate the bed form resistance. Empirical relations were formulated to calculate the bed form resistance and bed load transport rate using a newly defined flow parameter that incorporates the vegetation concentration. The bed elevations and bed form height were measured by the Microsoft Kinect 3D Camera. It was found that the height of bed form depends on the vegetation concentration, which determines whether ripple/dune or scour holes are dominant on the bed surface. For sparsely vegetated flows, the bed form height and resistance are decrease rapidly as the vegetation concentration was increased, and they decreased gradually when the vegetation concentration was high. To quantify the vegetation induced friction resistance, a 3D numerical simulation was conducted using the Delft3D-FLOW open source program. The study area is Davis Pond freshwater marsh area near New Orleans, Louisiana. The dominant vegetation type for the study area is Panicum hemitomon. The study area was divided into several sub-areas depending on the existence of channels, overbanks, and vegetation height. Several approaches were used to approximate the vegetation roughness; a constant Manning's n coefficient, a time-varying n or Chezy's C coefficient, and the modified momentum and k-ɛ equations for each subarea. To quantify the time varying roughness coefficients, four equations for calculating n values were incorporated in the Delft3D-FLOW program in addition to two options offered by this program to calculate C values. It is concluded that the use of the time varying roughness coefficient gives better results than other approaches. Among the selected equations to calculate the time varying vegetation roughness, the equations that account for the effect of the degree of submergence and the vegetation frontal area per unit volume, symbolized as a, gave the closet matches with the observations. The sensitivity of modeling results to the selection of vertical grid (σ–and Z-grids), a value, and grid size were analyzed. It is found that using the σ-grid yielded more accurate results with less CPU times and the best range of a value for the Panicum hemitomon vegetation type is from 8.160 to 11.220 m⁻¹. Also it was observed that the adoption of a coarse mesh gives reasonable simulation results with less CPU time compared with a fine mesh. A non-linear relation between the vegetation resistance, in terms of n value, and degree of submergence was observed.

Flow-vegetation interactions are critically important for most hydraulic and sediment processes in streams and rivers and thus need to be accounted for in their management. The central goal of this project therefore was to improve the understanding of flow-vegetation interactions in patchy-vegetated river beds, which are typical in rivers. Based on laboratory experiments covering a range of selected hydraulic and patch mosaic scenarios, the hydraulic resistance mechanisms, turbulence structure, and transport mechanisms were studied. The effects of regular patch mosaic patterns (aligned and staggered) on the bulk hydraulic resistance were investigated first. For the cases in which the relative vegetation coverage BSA in respect to the total flume bed is low (BSA = 0.1), the patches mutual positions do not affect values of the friction factor. When the parameter BSA increases to intermediate values (BSA = 0.3), the spatial distribution of the vegetation patches and their interactions become crucial and lead to a significant increase in the bulk hydraulic resistance. When further increase of the vegetation cover occurs (BSA = 0.6), the effects on hydraulic resistance of patch patterns vanish. To clarify the mechanisms of the revealed patch effects on the overall hydraulic resistance, flow structure was assessed at both scales: individual patch and patch mosaic. The presence of a submerged isolated vegetation patch on the bed introduces a flow diversion which strongly alters the velocity field and turbulence parameters around the patch. Coherent structures, generated at the canopy top due to velocity shear, control the mass and momentum transfer between the layers below and above the vegetation patch. At the patch mosaic scale, a complex three-dimensional flow structure is formed around the patches which depends on the patch spacing and spatial arrangements. For the low surface area blockage factor (BSA = 0.1), the patches are sparsely distributed and the wakes are (nearly) fully developed before they are interrupted by the effects of the downstream patches. At the intermediate surface area blockage factor (BSA = 0.3), significant differences in flow structure between the aligned and staggered patches were observed. For the highest surface area blockage factor investigated (BSA = 0.6) both aligned and staggered patch mosaic configurations showed a similar behaviour. The results on the flow structure are used to provide mechanistic explanation of the observed patch mosaic effects on the bulk hydraulic resistance.

Thesis: S.M., Massachusetts Institute of Technology, Department of Civil and Environmental Engineering, 2015.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 69-77).
The shear stress at the bed of a channel influences important benthic processes such as sediment transport. Several methods exist to estimate the bed shear stress in bare channels without vegetation, but most of these are not appropriate for vegetated channels due to the impact of vegetation on the velocity profile and turbulence production. This study proposes a new model to estimate the bed shear stress in both vegetated and bare channels with smooth beds. The model, which is supported by measurements, indicates that for both bare and vegetated channels with smooth beds, within a viscous sub-layer at the bed, the viscous stress decreases linearly with increasing distance from the bed, resulting in a parabolic velocity profile at the bed. For bare channels, the model describes the velocity profile in the overlap region of the Law of the Wall. For emergent canopies of sufficient density (frontal area per unit canopy volume a >/= 4.3m⁻¹ ), the thickness of the linear-stress layer is set by the stem diameter, leading to a simple estimate for bed shear stress.
by Qingjun (Judy) Yang.
S.M.

Yes
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.

This thesis present results relating to a series of laboratory experiments investigating the velocity field in order to provide an understanding into the flow structures by describing the mechanisms and transport features of heterogeneous (patchy) flexible and rigid strip vegetation flow interaction with gravel roughness which could be used to understand sediment transport in the future. The experimental results were examined in a context of shear layer arising as a result of flexible and rigid vegetation patchy roughness distribution with gravel roughness. It is shown that relative to a gravel bed, the vegetated section of the channel generally resembles a free shear layer. The resistance within the vegetation porous layer reduces the velocity and creates a transition of high velocity flow across the interface at the top of vegetation; of primary importance is the shear layer at the top of vegetation and roughness boundary regions which are shown to influence and dominate the overall momentum transport. These results have been used to calibrate a numerical model for the depth-averaged streamwise and boundary shear stress distribution using the Shiono and Knight Method (SKM). The model demonstrated approximately 90% accuracy in depth-averaged streamwise velocity distribution in comparison with the experimental data.

My Ph.D. project has focused on the characterization of TPK3, a putative channel selective for potassium (K+) with a predicted chloroplast localization in higher plants, from biochemical, physiological and electrophysiological point of view. This protein belongs to the TPK channel family (from Tandem-Pore K+ channels) and displays amino acid sequence homology with another K+ channel studied in our laboratory, called SynK (Zanetti et al., 2010). SynK shows thylakoid localization in Cyanobacteria. The SynK channel has been shown to be critical for photosynthetic performances in Cyanobacteria, given the photosensitive phenotype displayed by the mutants lacking the SynK protein. Given the homology, we hypothesized that similarly, TPK3 might be involved in the regulation of photosynthetic processes in higher plants. So far, no information is available about the properties of TPK3, nor about its physiological roles, neither about its possible involvement in photosynthesis; the work presented in this thesis had the aim of clarifying some important aspects of the functions of TPK3. Following subcellular localization studies carried out using biochemistry and confocal microscopy techniques, the TPK3 channel was expressed in E. coli cells for subsequent electrophysiological characterization in a planar lipid bilayer setup in order to prove its function as K+ channel. The unavailability of commercial mutants for tpk3 gene required setting up of a silencing procedure via RNA interference of the messenger for the protein, in order to analyze the possible physiological roles of TPK3. The resulting silenced plants have been studied under different growth conditions to determine changes in physiology of the plants including their photosynthetic parameters. In parallel with the TPK3 project, the most important part of my Ph.D., I also followed two other major areas of research: one concerning the study of the functions of two members of plant Glutamate Receptors (GluRs) and the other one concerning the characterization of the plant homologous of the recently identified MCU (Mitochondrial Calcium Uniporter) of mammals. This thesis also includes a manuscript (Checchetto et al., 2012) to which I contributed with the heterologous expression of a calcium-activated K+ channel, SynCaK, of Cyanobacteria.
Il mio progetto di dottorato si è focalizzato sulla caratterizzazione, dal punto di vista biochimico ed elettrofisiologico, di una proteina denominata TPK3 che è predetta di funzionare come canale selettiva per il potassio (K+) ed essere localizzata nei cloroplasti nelle piante superiori,. Questa proteina appartiene alla famiglia dei canali TPK (da Tandem-Pore K+ channels) e mostra omologia di sequenza a un altro canale del K+ studiato nello stesso nostro laboratorio, denominato SynK (Zanetti et al., 2010), a localizzazione tilacoidale ed appartenente al phylum dei Cianobatteri. È stato dimostrato in più esperimenti che il canale SynK è fondamentale per la regolazione della fotosintesi nei Cianobatteri, in considerazione del fenotipo fotosensibile mostrato dai mutanti per il gene synk. Visto la localizzazione predetta del TPK3, è stato ipotizzato in partenza che TPK3 potesse svolgere un ruolo simile nelle piante superiori. Finora nulla si conosceva sulle proprietà di TPK3, ne sui suoi ruoli fisiologici, ne su di un suo eventuale coinvolgimento nella fotosintesi nelle piante superiori; il lavoro contenuto nel progetto presentato ha cercato di chiarire alcuni aspetti salienti delle funzioni di TPK3. Dopo studi di localizzazione subcellulare condotti con tecniche di biochimica e microscopia confocale, il canale TPK3 è stato espresso in E. coli per la successiva caratterizzazione elettrofisiologica in bilayer lipidico planare allo scopo di determinare la sua funzione come canale di K+. L’assenza di mutanti commerciali per il gene tpk3 ha necessitato la messa a punto del suo silenziamento tramite RNA interference del messaggero per la proteina suddetta, al fine di analizzarne i possibili ruoli fisiologici. Le piante silenziate risultanti, sottoposte a differenti condizioni di crescita, sono state studiate in vari esperimenti atti a determinarne vari parametri inclusi quelli fotosintetici. Contemporaneamente allo studio del TPK3, quello di maggior rilievo nel mio dottorato, ho seguito anche altri due filoni di ricerca principali, riguardanti l’uno l’approfondimento delle funzioni di due membri dei Recettori di Glutammato vegetali (GluRs) e l’altro la caratterizzazione degli omologhi del recentemente identificato MCU (Mitochondrial Calcium Uniporter) di Mammiferi. Nella presente tesi è inoltre incluso un manoscritto (Checchetto et al., 2012) per il quale ho collaborato nell’espressione eterologa del canale di K+ calcio-dipendente (SynCaK) di Cianobatteri.

Crystallization of ion channel proteins is a difficult task for several reasons related to the hydrophobic nature of these proteins, and still is a matter of trials and errors. In this work I will present an experimental approach to the crystallization of a group of small potassium channels: the viral Kcv channels. The first part deals with the expression of MA-1D Kcv in the heterologous system Pichia pastoris and its purification by detergent solubilization. Attempts to increase the yield of the protein by modification of the construct at the DNA level are discussed. In parallel the production of Fab fragments from monoclonal antibodies that recognized the tetrameric form of the protein has been established in order to make protein-antibody complexes that can promote an ordered crystallization process by increasing the polar contacts within the crystals. In the second part of this thesis, the planar lipid bilayer technique is applied to study the functional properties of several Kcv channels at the single channel level. In particular I have analyzed the block by barium of the wt PBCV-1 Kcv and of its mutants in the 4th site of the selectivity filter, residue Threonine 63. This mutation affects protein sensitivity to barium, but also alters the open probability and the number of subconductance levels. The mutation of an adjacent aminoacid, Serine 62, recovers the wt functions. The T63 mutation was then moved also to another Kcv channel, MA-1D Kcv, to check if the behavior related to the mutation is conserved. The third part deals with Kesv, a Kcv-like channel founding a related class of viruses, ESV that, differently to Kcv, shows a mitochondrial localization when expressed in heterologous systems. Due to the difficulties encountered in measuring from mitochondria of transfected cells, we have not been able to record currents from this channel in the past. It was therefore decided to produce and purify recombinant protein for functional studies in artificial lipid bilayer. Since all attempts to express it in Pichia pastoris failed, it was decided to express it in a cell-free system in collaboration with the lab of Dr. Bernhard, at the University of Frankfurt. Functional studies on the reconstituted protein channel have revealed that the protein forms a functional, selective K+ channel with overall features of the Kcv-like channels.

Kcv from the chlorella virus PBCV-1 is a viral protein that forms a tetrameric, functional K+ channel in heterologous systems. Kcv can serve as a model system to study and manipulate basic properties of the K+ channel pore because its minimalistic structure (94 amino acids) produces basic features of ion channels, such as selectivity, gating, and sensitivity to blockers. We present a characterization of Kcv properties at the single-channel level. In symmetric 100 mM K+, single-channel conductance is 114 ± 11 pS. Two different voltage-dependent mechanisms are responsible for the gating of Kcv. “Fast” gating, analyzed by  distributions, is responsible for the negative slope conductance in the single-channel current–voltage curve at extreme potentials, like in MaxiK potassium channels, and can be explained by depletion-aggravated instability of the filter region. The presence of a “slow” gating is revealed by the very low (in the order of 1–4%) mean open probability that is voltage dependent and underlies the time-dependent component of the macroscopic current.

Previous field demonstration projects in metro-Atlanta have shown that seep berms, which are elongated sedimentation basins at the outlet of a disturbed land area, can provide high suspended sediment trap efficiencies with respect to coarse sediments on construction sites having drainage areas greater than five acres. Previous literature has shown that vegetative filter strips are efficient traps for fine suspended sediment in stormwater runoff. A combination of a seep berm and vegetative filter in series was studied in this thesis as an erosion control measure with quantification of its flow resistance and sediment removal efficiency. First, a field demonstration project was implemented to evaluate seep berms as a viable erosion control measure through a side-by-side comparison with the more commonly-used silt fences on construction sites with drainage areas less than five acres in metro Atlanta. High suspended sediment trap efficiencies were recorded for the seep berm on two separate sites, and the seep berm was shown to be superior to silt fences with respect to sediment control in the site runoff. Then a vegetative filter was studied in the laboratory in a specially-built flume for that purpose. The relationship between vegetative drag coefficient and various parameters reflecting flow conditions and vegetation density in steady, uniform open channel flow was studied in the flume. Both rigid, emergent vegetation and submerged, flexible vegetation were studied at two different plant densities. The application of porous media flow concepts to open channel flow through vegetation resulted in a collapse of data for vegetative drag coefficient for the various vegetation types and densities into a single relationship when plotted against vegetative stem Reynolds number. Point velocity and turbulence intensity profiles at different locations in the vegetative filter were recorded with an acoustic Doppler velocimeter to observe the turbulence structure of the flow and its effects on vegetative drag and settling of sediment. A sediment slurry consisting of a suspension of fine sand was fed into the flume, and an automated sampler was used to measure suspended sediment concentrations along the vegetative filter length for a series of discharges from which sediment flux and trap efficiency could be determined. Experimental data for trap efficiency were plotted against a dimensionless settling efficiency for each type of vegetation and density. These relationships, along with the one developed for the coefficient of drag, were applied in a numerical design technique that allows designers to determine the flow depth, velocity and trap efficiency of a vegetative filter of known dimensions for a given flow rate, sediment grain size distribution, slope, and vegetation density. In a typical design example, the combined trap efficiency proved that a seep berm followed by a vegetative filter can be a very effective erosion control measure.

Nel corso della loro vita le piante, essendo organismi sessili, sono continuamente soggette a cambiamenti ambientali che necessitano di essere accuratamente percepiti, a cui devono seguire appropriate risposte sia a livello locale che sistemico che ne garantiscano la sopravvivenza. Il calcio (Ca2+) è uno ione che agisce come importante secondo messaggero in tutti gli esseri viventi, in grado di accoppiare la percezione di uno stimolo extracellulare a peculiari risposte intracellulari. La specificità di trasduzione del segnale basata sul Ca2+ è ottenuta grazie alla generazione di transienti incrementi della sua concentrazione citosolica ([Ca2+]cyt), specifici nella loro evoluzione spaziale e temporale, alla quale ci si riferisce come “Ca2+ signatures”. La decodifica delle “Ca2+ signatures” da parte di proteine capaci di legare il Ca2+ permette la messa in atto di appropriate risposte fisiologiche. Nelle piante, è stato documentato che transienti variazioni citosoliche di Ca2+ sono coinvolte in svariati processi fisiologici che includono lo sviluppo della radice, lo sviluppo del tubetto pollinico e il processo di fecondazione, la risposta a stress abiotici, la regolazione dell’interazione pianta-microbo. Transienti incrementi nella [Ca2+]cyt con caratteristica intensità, frequenza, dinamica e durata sono generati dalla azione orchestrata di sistemi di influsso ed efflusso del Ca2+, che includono canali, pompe e scambiatori del Ca2+ che sono localizzati a livello delle membrane cellulari. Data l’importanza e l’universalità della trasduzione del segnale basata sul Ca2+, risulta essere di primaria importanza l’identificazione degli attori molecolari che governano la generazione dei segnali Ca2+. In questo contesto, lo studio delle dinamiche del Ca2+ in vivo rappresenta un potente strumento investigativo. Nel corso del mio dottorato di ricerca, ho esplorato il meraviglioso mondo del “Ca2+ imaging” utilizzando il vasto universo di Biosensori fluorescenti per il Ca2+ geneticamente codificati. Ho appreso e affinato tecniche per produrre immagini di alta qualità rappresentative di dinamiche del Ca2+ in vivo, sia a livello di intero organismo che a singola cellula. Le competenze che ho acquisito mi hanno permesso di contribuire a vari progetti tutti accomunati da quello che è un comune denominatore, ovvero il ruolo cardine del Ca2+ nella regolazione di svariati processi di trasduzione del segnale. Mi sono avventurato nello studio di vari aspetti legati alla segnalazione del Ca2+ tra cui: (i) gli aumenti della [Ca2+]cyt indotti nelle cellule dell’apice radicale in risposta a differenti amminoacidi, contribuendo a definire i determinanti molecolari sottostanti a tali risposte (Alfieri et al., 2020); (ii) la caratterizzazione dei transienti incrementi della [Ca2+]cyt indotti da auxine naturali e da molecole analoghe dell’auxina, e la decifrazione del ruolo di alcuni attori molecolari coinvolti nella genesi delle risposte [Ca2+]cyt indotte da auxina (Wang, Himschoot, Grenzi et al., 2022); (iii) lo sviluppo di un nuovo biosensore per il Ca2+ geneticamente codificato per indagare il ruolo del reticolo endoplasmico nella modellazione delle “Ca2+ signatures” in processi di sviluppo, così come in risposta a vari stimoli (Resentini, Grenzi et al., 2021); (iv) l’effetto di modulazione che alcuni composti chimici hanno sulle oscillazioni spontanee nella [Ca2+]cyt delle cellule di guardia che governano l’apertura e la chiusura degli stomi. Ho inoltre contribuito alla scrittura di reviews legate al mondo del “Ca2+ signalling” in pianta. Tutti i lavori pubblicati, così come i lavori in preparazione, sono allegati al termine di questa dissertazione, alla quale rimando gentilmente il lettore. Qui presenterò il lavoro portato avanti nel contesto del mio progetto di dottorato, il quale si è focalizzato principalmente alla comprensione dei meccanismi rapidi di segnalazione a lunga distanza. Le risposte sistemiche sono governate da eventi di segnalazione a lunga distanza che richiedono l’attività dei Recettori del Glutammato (GLRs). I GLRs sono proteine omologhe ai Recettori del Glutammato animali (iGluRs), ovvero canali ionici attivati da ligando presenti nel sistema nervoso centrale. Nonostante negli animali è chiaro che gli iGluRs mediano il passaggio di ioni a seguito del loro legame con il L-Glutammato, il meccanismo attraverso cui i GLRs sono attivati in pianta è ancora largamente discusso. Ad esempio, non si è ancora a conoscenza se il legame dell’aminoacido ai GLRs sia realmente necessario per la loro attivazione. In questo lavoro di tesi, analizzando i dati della struttura cristallografica del Dominio di Legame all’ amminoacido (LBD) del AtGLR3.3 di Arabidopsis thaliana, abbiamo identificato dei residui amminoacidici coinvolti nel legame del glutammato. Abbiamo dunque introdotto mutazioni puntiformi nella sequenza genomica del AtGLR3.3 per inficiare o abolire la sua abilità di legare il ligando amminoacidico, e con i costrutti ottenuti abbiamo eseguito una complementazione genetica dei mutanti knock out per il gene GLR3.3 (glr3.3-1 e glr3.3-2). Combinando analisi di imaging, genetica, e bioelettronica, dimostriamo che un danno a livello della foglia, come una ferita o una bruciatura, e l’applicazione di uno stress ipoosmotico alla radice, inducono l’aumento sistemico nella concentrazione apoplastica di L-Glutammato che attiva i GLRs attraverso il legame al loro LBD. Inoltre, il nostro lavoro supporta l’evidenza che gli eventi di segnalazione a lunga distanza siano governati da cambiamenti nello stato di turgore della pianta e che i GLRs siano a valle di essi.
Throughout their life plants, being sessile organisms, are continuously exposed to environmental challenges that need to be properly perceived and that require appropriate local and systemic responses. Calcium ion (Ca2+) is a key second messenger in all living beings that couples the perception of extracellular stimuli to characteristics intracellular responses. The specificity of the Ca2+-based signalling is achieved through the generation of specific spatial and temporal transient elevations in the cytosolic Ca2+ concentration [Ca2+]cyt, which are referred to as “Ca2+ signatures”. The interplay of Ca2+ signatures with a toolkit of cognate Ca2+-binding proteins that decode these increases allow the plant to implement a series of tailored physiological responses (e.g., gene expression, metabolism, developmental reprogramming) to withstand the stress. In plants, transient increases in the [Ca2+]cyt have been documented to be involved in several physiological processes including root or pollen tube growth and fertilization, abiotic stress responses, plant-microbe interaction. Ca2+ transients with unique magnitude, frequency, shape, and duration are generated by the orchestrated action of Ca2+ influx and efflux systems that include Ca2+ channels, pumps, and exchangers located at different cellular membranes. Given the importance and universality of Ca2+-based signalling, the identification of actors of the molecular machinery that govern the generation of Ca2+ signals is of primary importance. In this context, the study of Ca2+ dynamics in vivo represents a powerful tool. In the frame of my PhD, I explored the marvellous world of Ca2+ imaging using some of the instruments made available from a vast universe of genetically encoded fluorescent Ca2+ biosensors. I learned and refined techniques to produce high-end images of in vivo Ca2+ dynamics both at the entire organism and single-cell level. The expertise that I acquired allowed me to contribute to different projects, all unified by the common denominator that is the master regulatory role of Ca2+ in many signalling processes. I therefore contributed to the study of: (i) the [Ca2+]cyt responses of root tip cells in response to different amino acids, helping to define the molecular determinants involved in the process (Alfieri et al., 2020); (ii) the characterization of [Ca2+]cyt transients induced by the administration of natural auxins and auxin analogues, and the deciphering of the role of molecular actors involved in the genesis of the auxin-induced [Ca2+]cyt response (Wang, Himschoot, Grenzi et al., 2022); (iii) the development of a novel genetically encoded Ca2+ biosensors to unravel the role of the endoplasmic reticulum in the shaping of the Ca2+ signature in developmental processes, as well as in response to various stimuli (Resentini, Grenzi et al., 2021); (iv) the modulatory effects of chemicals on the spontaneous [Ca2+]cyt oscillations of guard cells that govern the opening and closing of stomata. I also contributed to the preparation of reviews linked to the field of Ca2+ signalling. All the published manuscripts, as well as works in preparation, are attached at the end of this dissertation, to which I kindly redirect the readers. Here, I am presenting the main work of my PhD project which focused on the understanding of how local damages can trigger inducible defence mechanisms in systemic organs and tissues. Systemic responses are mediated by long-distance signalling that requires the activity of Glutamate Receptor-Like channels (GLRs). GLRs are homologs of animal Ionotropic Glutamate Receptors (iGluRs) which are ligand-gated cation channels in the central nervous system. Even though iGluRs are gated through the binding with the L-Glutamate, the mechanism throughout GLRs are activated in planta is poorly understood. As an example, we still do not know if the GLRs binding of amino acids is necessary for their activity. In this PhD thesis, we took the advantage of the recently obtained crystal structure of the Arabidopsis thaliana AtGLR3.3 Ligand Binding Domain (LBD) to identify residues involved in the amino acid-binding. We, therefore, introduced single point mutations in the genome sequence of the AtGLR3.3 gene to prevent or abolish its amino acid-binding, and with the obtained constructs we complemented the glr3.3 KO. By combining high-end imaging, genetics, and bioelectronics we prove that leaf injury, such as wound and burn, and root-applied hypo-osmotic stress induce the systemic apoplastic increase of L-Glutamate that activates GLR channels through their LBD. In addition, our work supports the evidence that long-distance signalling is governed by a systemic change in the turgor state and that GLRs are downstream of it.

The diploma thesis is focused on the proposal of systematic revitalization of the selected section of the Knínický brook in the cadastral area of Veverské Knínice. It is a straight, very deep channel due to technical adjustments in the past. The HEC-RAS program verifies the capacity of the channel for the Q100 flow. In this way, it was found that the channel has very high capacity so a new route with Q1 flow capacity was designed. Due to the height conditions, the design also included three boulder chutes. Subsequently, the vegetation accompaniment and bank stands were suitably supplemented.

Nowadays plant derived compounds constitute a promising resource in ecofriendly pest and diseases management because they are ‘generally recognized as safe’ (GRAS). Plants have evolved ingenious defense mechanisms by production of pungent and irritant compounds. These substances produce their psychophysical effects by targeting the TRPA1 receptor, belonging to transient receptor potential (TRP) channels. Two secondary metabolites contained in the Asian food plant Perilla frutescens, perillaldehyde (PA) and perillaketone (PK), are potent agonists of TRPA1. The aim of the present PhD project was to determine the antimicrobial activity of the crude extracts and essential oils from the leaves of two Perilla frutescens varieties grown experimentally in Northern Italy. Commercial PA and PK, obtained by chemical synthesis, were also assayed in vitro and in vivo (PA, only). In addition, the nematicidal efficacy of pure PK was evaluated against 2nd instar larvae juveniles of cyst nematode Heterodera daverti. Chemical analysis allowed the identification of PA and PK as the main constituents in the two investigated cultivars respectively, and the consequent classification in PA and PK chemotypes. The organic extracts PA and PK-type (PA-Ex and PK-Ex) and the essential oils PA and PK type (PA-EO and PK-EO) exhibited a broad spectrum of activity against tested phytopatogenic organisms. The antibacterial activity of the tested substances resulted generally scanty. In vitro antifungal activity varied according to compound and target species. The essential oils appeared to be significantly more active compared with the crude extracts. At 500 µg mL-1 PA-EO showed fungicidal activity against several fungi while PK-EO exhibited a fungistatic one. Both oils and commercial PA displayed high inhibition on Cladosporium cladosporoides IPV-F167 spore germination, while PA-Ex and pure PA proved good preventive activity reducing powdery mildew disease on cucumber plants. Besides, P. frutescens demonstrated to possess efficient nematicidal activity due to PK.

The object of this Master`s thesis is the river training of the Luha river in Jeseník nad Odrou. The thesis is divided into several chapters. In the theoretical introduction, the problems of the sediment flow regime are discussed. Moreover, it deals with the questions associated with the roughness in open channels and adjustment of riparian zones. As a part of the overall proposal of the flow adjustment, the hydraulically most suitable cross section in cunette is proposed. It is done with respect to the desired velocity ratios in the profile. Since the new cunette shape was established, the adjustment of vertical alignment was proposed. The thesis also contains the capacity assessment of the existing channel. Design of adjustment of flood protection measures includes mainly spatial rearrangement and increase the crest of levees with respect to the local conditions. The thesis also suggests the placement of vegetation in the riparian zones. Furhermore, the work deals with problems arising from the flow adjustment considering applicable laws and regulations of the Czech Republic. In the case of project implementation, it is necessary to evaluate these problems independently.

Determination of immeasurable parameter, the Manning’s roughness coefficient, is a complex problem of open channel hydraulics for more than 200 years. Now it doesn’t exists a method for determining an exact value of 1D roughness coefficient for computation water levels in watercourses. Doctoral thesis is focused for comparing different approaches to determine a roughness coefficient, especially for empirical equations. It were sought empirical equations, which are suitable for wide spectrum of water stages, types of bed material, channel shapes and channel dimensions. Selected equations were sorted on the base of two methods by the best values of medians and standard deviations of measured and computed values of roughness coefficients. Furthermore, it were compared qualities of roughness coefficient determination by tables, by photographic catalogs, CES software and by Cowan’s method, which has been extended and recalibrated. The computed values of roughness coefficients by those four methods were compared with values from own measurements in 27 locations in watercourses near of Brno and Frýdek-Místek. Also it were compared the grain size curves determined by sieving, by Wolman’s method and by Subjective estimation. Doctoral thesis is marginally focused for beginning of sediment movement, roughness coefficient of bedforms (dunes), grass and trees.

碩士
國立成功大學
水利及海洋工程學系碩博士班
94
The vegetation in the floodplain and along the bank can increase roughness of the ground, retard the flow velocity, and bear some shear force. Hence, it can prevent bed erosion and enhance bank stability. However, the water stage was rise and conveyance of flow was retard due to decrease of wetted cross-sectional area. In recent years, the hydraulic phenomenon about flow resistance for the vegetation is more and more important cause of the ecological engineering methods were used. The purpose of this study was to investigate the effect of vegetation, that include the interrelation between both the flow above and through the vegetation and the vegetation densities, in steady gradually varied flow by laboratory experiment and theoretical analysis. The cylinders were used to simulate the stems of vegetation because of their shapes are similar. The exchange of momentum between the flow above and through the vegetation, and the hydraulic resistance were analyzed by the one-dimensional steady gradually varied flow. Equations derived based on the conservation of mass and momentum may be expressed as : Continuity equation: Momentum equation: The formula of dimensionless turbulent length ratio can be mathematically described in turbulent shear stress on the interface between upper and lower level. The formula was useful for calculating the discharge of the upper and lower level. The results indicated that the influence of the resistance coefficient by submerged cylinders on cylinder densities, submergence ratio, and cylinder Reynolds number. Therefore, the condition with the same submergence ratio in the channel, the dense cylinders decrease in both the resistance coefficient and the flow velocity and increase in water stage when the flow through the submerged dense cylinders. In this study, the one-dimensional numerical model was developed by the finite difference scheme was applied to discrete the governing equations that was steady gradually-varied flow in the vegetated channel and proved by laboratory experiment. The numerical model was applied to simulate the flow depth and discharge in the emergent and submerged vegetated channels well. The results of experiment and simulation indicated that the flow discharge was changed both above and through the vegetation and along the direction of flow. According to the results that were increase in the understanding to the phenomenon of flow through vegetation and application of reality. Moreover, the influence of flow on the difference vegetation density was simulated by model. Keywords：vegetation；steady gradually varied flow；resistance coefficient

博士
國立臺北科技大學
工程科技研究所
97
The vegetation in channels results in loss of energy and retardance of water flow. However, this vegetation helps to stabilize the slopes and bottoms of open channels. Recently, vegetated channels have been used to improve the surface water quality and to reduce the delivery of sediment and nutrient to rivers and swales. Therefore, it is important to understand the velocity distribution of vegetated channels. The velocity distribution above canopy is usually assumed to follow the well accepted logarithmic law, whereas the velocity distribution below canopy is expressed by exponential law or power law. However, logarithmic, exponential and power laws can be affected by some characteristics of vegetation resulting in the sufficiently inaccurate description of velocity distributions in vegetated channels. In this study, and velocity distribution equation based on probability is developed to simulate the velocity distribution of vegetated channels in the submerged condition. An extensive series of laboratory experiments planted with Egeria densa Planch in the channel bed of the flume are carried out to devise and validate the velocity distribution equation. The results indicate that the developed model of velocity distribution have the applicability and capability to simulate the velocity distribution effected by aquatic vegetation. The other important parameter of vegetated channel is retardance coefficient. Manning Equation is widely adopted to estimate open channel flows, and selecting retardance coefficient is always one of the most difficult task for estimating velocity and discharge. In cases of estimating accurate retardance coefficient values of vegetated channels, countless trial and error are to be made before reaching conclusive results due to conditions created by various aquatic plants. The majority of past studies on this subject, however, are established based on terrestrial plants and plastic moulds as laboratorial factors, and only few are done with natural aquatic vegetations. Hence, in this study, two different types of natural aquatic plants are applied to estimate retardance coefficients; and the result indicates that each type of plant affects differently in terms of flow resistance. Analysis of hydraulic parameters indicates there are strong correlations between the retardance coefficient and the Froude number. The Froude number is most important and commonly used parameter of open-channel hydraulics. The retardance coefficient and Froude number are exponentially related. Therefore, the Froude number can replaces the product of velocity and hydraulic radius (VR) to estimate the retardance coefficient, in which VR lacks a physical mean. Additionally, it can be used accurately to estimate velocity and discharge during river and wetland restoration.

碩士
國立成功大學
水利及海洋工程學系碩博士班
96
When the flood occurs and water flows above the vegetation in the floodplain, the vegetation can increase roughness and retard the flow velocity so that this can prevent bed erosion and enhance bank stability. In addition, it also maintains ecological condition and increases the value of landscaping entertainment. However, the existence of plants will increase the capacity of the main zone and affect on the sediment transport. Hence, the analysis of the discharge in the mainstream is imperative. The main objective of the present study is to investigate the hydraulic phenomenon of the partly-vegetated channels and the flow capacity of the main zone (non-vegetated zone). In the steady gradually-varied flow, we could derive governing equations of the partly-vegetated open channels under a submerged situation and then design the laboratory experiment. To examine the influence of stems on the experiment, stiff cylinders were used to simulate the stems of the vegetation. Based on our research, some crucial results can be drawn: 1. When the flow moves into vegetated channels, it is found that the stages of each cross section in the vegetated and non-vegetated (main channel) zones are almost the same. By assuming the water level to be the horizontal, the momentum and energy equations were obtained mathematically. 2. The velocity distributions were obviously different between the main channel and vegetated channels (i.e. upper and inner the vegetation). After anallyzing the experimental data, we obtained correction factors ( and ) for the formulas of momentum and energy. ( 4-12 ) ( 4-13 ) 3. In the upstream of the vegetated channels, the velocity distribution is closed to be uniform. It was the spatially-varied flow when the water flows into the vegetated channels and the discharge was increased from the upstream to the downstream, including the non-vegetated zone and inside the vegetation; it was decreased along the channels within the vegetation. Around the exit of the vegetated channels, the discharge of the main zone is decreased with the spatially varied condition. Based on the analysis of the experimental date, we could get the relation between the discharge of the main zone and all cross sections, which can be expressed by (4-3). ( 4-3 ) 4. Based on the assumption that the energy slope was equal to the friction slope in the one- dimension steady gradually-varied flow, we derived the expression of the Manning roughness coefficient from the vegetation steam drag coefficient and friction coefficients of bed and wall. The application of the Manning roughness coefficient was verified to be very well from experiment data, which is within the 10% error. ( 2-37 ) ( 2-40 ) 5. It was over contraction in the partly-vegetated channels if the density of the vegetation is great enough, and then the supercritical flow can be observed in the main zone. The hydraulic jump occurs at the end of the channel, because the flow condition changes from the supercritical flow to the subcritical flow. The discriminant of hydraulic jump could be compared with experimental data, which is express by (4-1): ( 4-1 ) Based on the formulas of the energy equation, Manning rough coefficient, the energy correction factor, as well as the ratio of the discharge within the main zone and all cross sections, the discharge of the main zone can be determined in order to get the capacity of the main zone following the standard step method under the one-dimensional steady gradually varied flow.

碩士
國立成功大學
水利及海洋工程學系碩博士班
96
There is a close relationship between the stability of main channel in alluvial river and the dominant discharge. Dominant discharge is defined as the main channel discharge nearby the bankfull stage. As the main channel stage is near or over the bankfull stage, the water will overflow into the floodplain. For the thick vegetated floodplain, the near-bankfull stage flow will not submerge the floodplain vegetation. Because vegetation roughness is always larger than main channel roughness, it is necessary to discuss the influence of floodplain vegetation on main channel discharge to analyze the effect of vegetation for main channel stability and surrounding environmental protection. This research aims to maintain part of the width of the channel without vegetation while the other part lays out vegetation with different density. Meanwhile, to discuss the discharge distribution under the situation that steady gradually varied flow flows through emergent vegetation by theoretical analysis and laboratory experiment, in order to apply to investigate the dominant discharge of alluvial river. From the experimental results, when steady gradually varied flow flows into the emergent partly vegetated open channel from non-vegetated open channel, because of the effect of the vegetation drag force, the main channel discharge increases significant along the flow direction but will be gradually constant. And then it decreases as it is getting close to the outlet. With the experimental observation, it is clear to see as the vegetative density increases, the main channel discharge increases as well. Therefore an analysis of the influence of vegetative density on main channel discharge is needed to be studied. Based on the experimental results, the main channel stage is approximately equal to the vegetation stage in the vegetative reach. Hence the transverse water line is regarded as a horizontal line. By the experimental results, an assumption of the transverse water line as a horizontal line was made in this research, which conducts the momentum equations of vegetation zone, main channel zone, and full cross-section according to the momentum conservation theorem. Because the velocity between main channel and the vegetation are significant different, this research calculates the kinetic energy correction factor and the momentum correction factor according to the experimental velocity data, and then compares with the kinetic energy correction factor and the momentum correction factor calculated with the mean velocity of the vegetation zone and main channel zone. The results show each of them is approaching to each other. Therefore the mean velocity of the vegetation zone and main channel zone are accurate enough to calculate the kinetic energy and the momentum correction factor. Applying Moody chart to obtain the friction factor of the channel bed and wall, and then using the momentum equation of full cross-section to analyze the drag force factor of the vegetation cylinder according to the experimental data. The value is between 0.6 and 1.2, the average value is 0.9. And then using the momentum equation of main channel zone to analyze the non-dimension turbulent mixing length ratio, the square of its value is between 0.01 and 0.45, the average is 0.23. The aforementioned analysis results will be applied to the momentum equations of main channel zone and full cross-section to solve the main channel discharge and cross-section average depth by mathematical method. Because mathematical method is more complicated, based on the experimental data, this research uses dimension analysis method to obtain the experiential formula for the ratio that main channel discharge is divided by full cross-section discharge : （4-13） The value calculated by formula ( 4-13 ) is compared with the experimental value, and the result shows the agreement that it will be applied to estimate the main channel discharge of the emergent partly vegetated open channel with orthogonal cross-section. Due to the drag force and the contraction that vegetations act on the water, the emergent partly vegetated open channel will cause the excessively contraction and the supercritical flow. At the same time, because of the subcritical flow downriver, it will also cause the hydraulic jump. This research conducts the discriminant of the hydraulic jump of emergent partly vegetated open channel to distinguish the hydraulic jump according to the vegetative density of the partly vegetated reach , the ratio that the vegetated width is divided by the full cross-section width , and the Froude number : （2-32） The phenomenon of the hydraulic jump of each run in the experiment is compared with formula ( 2-32 ), the result shows the agreement that it is a practical discriminant of the hydraulic jump. Based on the theory and experimental analysis in this research, it is obviously to see that the partly vegetated open channel will increase the main channel discharge because of the influence of the vegetative density, and even occur the supercritical flow and the hydraulic jump. Therefore applying vegetations to protect the bank should review whether the increasing of main channel discharge will affect the erosion and deposition of the main channel bed or not. Based on the results of this research, it also exhibits that the dominant discharge of main channel in alluvial river should be analyzed according to the vegetative condition of the floodplain.

Vegetation is a fundamental feature of riverine ecosystems, playing a variety of valuable ecological and biological roles. Concurrently, the presence of vegetation and its interaction with the flow alter the mean and turbulent flow field, with implications on flow resistance, water conveyance and transport of mass and energy. The proper understanding of these vegetation-influenced processes is essential for solving the existing and future river management challenges, concerning both societal needs and ecosystem requirements. The objective of this thesis is to provide new insight on the flow-vegetation hydrodynamic interaction with a specific focus on partly vegetated channels, a configuration representative of natural settings. Indeed, in natural watercourses, vegetation is generally found along river margins, partly obstructing the river cross-section and laterally interacting with the flow. Riparian vegetation presents a complex morphology and, owing to its flexibility, exhibits a dynamic and reconfiguring behavior under the flow forcing. In the analysis of flow in partly vegetated channels, these flow-influencing characteristics have been generally neglected, simulating vegetation with rigid cylinders. In the current study, two main experimental campaigns were performed to investigate the turbulent structure of the flow in partly vegetated channels, simulating vegetation with natural-like plant stands (PN) and with rigid cylinders (PR). The PN tests aimed at investigating the effects of plant morphology, reconfiguration and dynamic motions on the turbulent flow field. Furthermore, the effects of seasonal variability of plants on flow structure were explored. Results showed that plant morphology and reconfiguration play a key role in the vegetated shear layer dynamics, significantly affecting the exchange processes across the vegetated interface. The PR test series was performed to investigate the effects of vegetation density on the turbulent flow structure. The results showed that, for rigid vegetation, the density directly affects the shear layer features, governing the onset of large-scale coherent structures. Finally, the impacts of embedding natural plant features in the simulation of partly vegetated flows were explored by comparing the shear layers induced by complex morphology vegetation (PN) and by rigid cylinders (PR). In addition, an existing model for velocity prediction was tested against the experimental results, showing the need to improve existing models for taking into account the peculiar hydrodynamic behavior of natural vegetation.

Yes
Simulation of the suspended sediment concentration (SSC) has great significance in predicting the sediment transport rate, vegetation growth and the river ecosystem in the vegetated open channel flows. The present study focuses on investigating the vertical SSC profile in the vegetated open channel flows. To this end, a model of the dispersive flux is proposed in which the dispersive coefficient is expressed as partitioned linear profile above or below the half height of vegetation. The double-averaging method, i.e. time-spatial average, is applied to improve the prediction accuracy of the vertical SSC profile in the vegetated open channel flows. The analytical solution of SSC in both the submerged and the emergent vegetated open channel flows is obtained by solving the vertical double-averaging sediment advection-diffusion equation. The morphological coefficient, a key factor of the dispersive coefficient, is obtained by fitting the existing experimental data. The analytically predicted SSC agrees well with the experimental measurements, indicating that the proposed model can be used to accurately predict the SSC in the vegetated open channel flows. Results show that the dispersive term can be ignored in the region without vegetation, while the dispersive term has significant effect on the vertical SSC profile within the region of vegetation. The present study demonstrates that the dispersive coefficient is closely related to the vegetation density, the vegetation structure and the stem Reynolds number, but has little relation to the flow depth. With a few exceptions, the absolute value of the dispersive coefficient decreases with the increase of the vegetation density and increases with the increase of the stem Reynolds number in the submerged vegetated open channel flows.
the Natural Science Foundation of China (Nos. 11872285 and 11672213), The UK Royal Society – International Exchanges Program (IES\R2\181122) and the Open Funding of State Key Laboratory of Water Resources and Hydropower Engineering Science (WRHES), Wuhan University (Project No: 2018HLG01)

The aim of this Doctoral thesis is to analyse experimentally, by using measures of instantaneous velocity carried out through a laser Doppler anemometer, the behaviour of streams flowing on a rigid vegetated bottom, realized by means of brass cylinders, and characterized by different height and density. A particular attention has been paid to the effects that such a type of vegetation has both on the flow resistance and on the distributions of the main statistical quantities of the turbulence, such as local mean velocity, and variance, skewness, kurtosis of the fluctuating velocities, and finally longitudinal integral length scales obtained through the autocorrelation function. Measurements are carried out both in boundary layer and in uniform flow currents.

Yes
The present study investigates the turbulent hydrodynamics in an open channel flow with an emergent and sparse vegetation patch placed in the middle of the channel. The dimensions of the rigid vegetation patch are 81 cm long and 24 cm wide and it is prepared by a 7× 10 array of uniform acrylic cylinders by maintaining 9 cm and 4 cm spacing between centers of two consecutive cylinders along streamwise and lateral directions respectively. From the leading edge of the patch, the observed nature of time averaged flow velocities along streamwise, lateral and vertical directions is not consistent up to half length of the patch; however the velocity profiles develop a uniform behavior after that length. In the interior of the patch, the magnitude of vertical normal stress is small in comparison to the magnitudes of streamwise and lateral normal stresses. The magnitude of Reynolds shear stress profiles decreases with increasing downstream length from the leading edge of the vegetation patch and the trend continues even in the wake region downstream of the trailing edge. The increased magnitude of turbulent kinetic energy profiles is noticed from leading edge up to a certain length inside the patch; however its value decreases with further increasing downstream distance. A new mathematical model is proposed to predict time averaged streamwise velocity inside the sparse vegetation patch and the proposed model shows good agreement with the experimental data.
Debasish Pal received financial assistance from SRIC Project of IIT Kharagpur (Project code: FVP)

碩士
萬能科技大學
工程科技研究所
96
Considering the channel slope and vegetated revetment, this research makes the according channel test and analyzes the hydraulic properties on trapezoid channel. The result analyzed from test data shows that Manning’s coefficient of vegetated revetment (nw) increases and then decreases with the channel slope (S) at the same flux (Q) and channel slope (Sw). The nw value is the largest at Sw = 10.4 and then approaches a constant value. Under the same flux, the nw value decreases with S. In addition, the smaller flux has a larger influence on the nw value. Under the same S, the nw value first decreases and then increases with Q. When S = 0.04, the nw value significantly increases with Q. In addition, the larger S has a larger influence on the nw value. The relations of Manning’s coefficient of channel (n) and S have the similar results for those of the nw value and S. However, the n value is smaller than that of the nw value. Applying the linear regression analyses, the relations of the Froude number (NF) and nw and n are given as nw = -0.0029NF2 - 0.0161NF + 0.0667 and n = 0.0049NF2 - 0.0292NF + 0.0556, respectively. In addition, the relation of n - nw is given as n = 2.2544nw2 + 0.7825 nw - 0.0109. The regression functions are helpful to design the practical application in a hydraulic engineering. The influence factors of the hydraulic and channel properties are considered on ecological channel. Applying the dimension analysis, the influence parameters can be changed to dimensionless parameters. The multiple regression analysis of the SPSS software are used to obtain the functions of Manning’s coefficient and dimensionless parameters and the final results are given as and . The percentage differences between the roughness coefficients obtained by the separation-area method and the multiple regression model are -4.89 ~ 7.39 % for the nw valve and -5.29 ~ 6.39 % for the n valve. The result shows that this model can appropriately interpret the test data. The regression functions are helpful to design the practical application in ecological engineering. Under the known of hydraulic conditions for trapezoid channel, these functions can be used to estimate effectively the roughness coefficients of the vegetated revetment and channel on trapezoid channel. In addition, it can promote conveniently the hydraulic design of ecological engineering.

碩士
國立交通大學
土木工程系所
93
There are three types of the reactions of the vegetation: erect, waving and prone when flow passes vegetated channel. This study focuses on the erect type to investigate the influence of different vegetated density on the variation of velocity. The cylinder of resin is used as the model plant, with diameter of 0.65 cm and height of 3 cm. There are seven sets of vegetated density. The characteristic volume ratio is used to represent the vegetated density, and it is defined as ratio of the plants’ volume to unit fluid volume. The flow discharge in the experiment is controlled in the range of 70(l/min)∼90(l/min) and the flow depth is 5 cm in the upstream boundary. Because the flow is affected by the vegetation, the flow field changes rapidly. If the traditional single-point measurement at a time is adopted in the experiment, the variation of the velocity field in the vegetated channel cannot be obtained completely and effectively. Hence, this study adopts non-intrusive color particle image velocimety (CPIV) to measure the vertical 2-D flow field in the vegetated channel. The CPIV method uses Argun laser as the light source, the PCAOM separates the light into blue and green lights and they form a light sheet after emitting on a rotating eight-side mirror, the CCD takes the instantaneous images of vegetated channel flow field, and then obtains the velocity field through the set-up of interrogation window and image analysis. Finally, the associated vorticity can be calculated by the central difference scheme based on the measured velocity components at each point. After measuring the vegetated channel flow field with the CPIV method, the stronger vorticities occur in the interface between air and fluid, near the bed of the vegetated channel and the vicinity of the model plant. In addition, the relationships among the increasing rates of the mean and maximum velocities and the distance from the water surface of the maximum velocity at the top of the third-row model plant with respect to the characteristic volume ratio are also analyzed. It can be found that the exponential relationships exist with high correlation coefficients.