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Previous issue date: 2017-08-29 / A vegeta??o macr?fita possui um papel importante na manuten??o e equil?brio dos ambientes aqu?ticos em rios e lagos nas regi?es tropicais. Em cursos d??gua de pequeno porte, essas plantas proporcionam benef?cios ecol?gicos, pois atuam na sedimenta??o e reten??o de nutrientes, propiciando melhoria nas propriedades f?sico-qu?micas da ?gua. A presen?a de macr?fitas na calha fluvial alteram o comportamento da velocidade e aumentam a resist?ncia ao fluxo, com redu??o da velocidade na se??o e aumento da profundidade. Em geral, o retardamento do escoamento est? associado a fen?menos indesej?veis, tais como inunda??o de ?reas ocupadas. O objetivo deste estudo foi investigar o comportamento da resist?ncia ao fluxo provocado pela presen?a de vegeta??o macr?fita r?gida emersa da esp?cie Aninga (Montrichardia linifera) num trecho do rio Pitimbu situado na regi?o metropolitana de Natal. Para isso foram realizadas duas campanhas hidrom?tricas, realizadas em 12/04/2017 e 15/09/2017. A metodologia empregada consistiu na medi??o de vari?veis hidr?ulicas e levantamento in situ das caracter?sticas da vegeta??o no trecho e analise da intera??o fluxo-vegeta??o. A analise da vegeta??o envolveu a delimita??o de quatro quadrantes (4 m2) definidos aleatoriamente na ?rea de estudo. Nesses quadrantes foram levantadas as caracter?sticas morfol?gicas das plantas e a distribui??o espacial. A medi??o das vari?veis hidr?ulicas foi feita com a discretiza??o das se??es transversais em verticais, onde foram medidas as velocidades medias pontuais. A vaz?o e o numero de Manning obtidos nas campanhas 1 e 2 foram 0,2467 m?/s e 0,069 m-1/3s; 0,2076 m?/s e 0,078 m-1/3s respectivamente. A densidade da distrbui?ao espacial da vegeta??o era 8,12 plantas/m2. O comportamento da velocidade na se??o S1 demonstrou alta variabilidade espacial, com alguns valores acima da m?dia. Esse comportamento estava associado a presen?a de vegeta??o. Foram registradas velocidades negativas em algumas regi?es a jusante das plantas, indicando a gera??o de esteiras e fluxo reverso nestes locais. O padr?o de distribui??o espacial da vegeta??o era agregado em algumas regi?es da comunidade de plantas. A intera??o fluxo-vegeta??o foi analisada a partir de uma sequ?ncia de registros fotogr?ficos. Foi poss?vel identificar o comportamento dos fluxos atrav?s das plantas: regi?es de descolamento da camada limite, regi?es de esteira e de forma??o de v?rtices. / Macrophyte vegetation plays an important role to keep balanced aquatic environments in rivers and lakes in tropical regions. In small water courses, these plants provide ecological benefits since they act on sedimentation and nutrients retention, leading to an improvement in the water physicochemical properties. The presence of macrophytes in the river channel changes the velocity behaviour and increases the resistance to flow, causing reduction in speed and increase of depth in the section. Generally, flow retardation is associated to unwanted events, such as flooding of occupied areas. The aim of this study was to investigate the hydraulic resistance behaviour to flow caused by the presence of rigid and emersed macrophyte vegetation of the species Aninga (Montrichardia linifera) in a section into Pitimbu River located in the metropolitan region in Natal. Two hydrometric campaigns were carried out on 04/24/2017 and 09/15/2017. The methodology used included measurement of hydraulic variables, in situ survey of vegetation characteristics and analysis of the flow-vegetation interaction. Vegetation analysis involved the delimitation of three quadrants (4 m2) defined in the study area. In these quadrants, the morphological characteristics of the plants and the spatial distribution were raised. The hydraulic variables were measured with the discretization of the cross sections in verticals, where the average speeds were measured. Manning flow and number obtained in campaigns 1 and 2 were 0.2467 m?/s and 0.069 m-1/3s; 0.2076 m?/s and 0.078 m-1/3s s respectively. The density of the spatial distribution of vegetation was 8.12 plants / m2. The velocity behavior in section S1 showed high spatial variability, with some values above average. This behavior was associated with the presence of vegetation. Negative velocities were recorded in some regions downstream of the plants, indicating the generation of mats and reverse flow at these sites. The pattern of spatial distribution of vegetation was aggregated in some regions of the plant community. The flow-vegetation interaction was analyzed from a sequence of photographic records. It was possible to identify the behavior of the flows through the plants: regions of boundary layer detachment, belt regions and vortex formation.
| Identifer | oai:union.ndltd.org:IBICT/oai:repositorio.ufrn.br:123456789/24229 |
| Date | 29 August 2017 |
| Creators | Vitorino, Camila Farias |
| Contributors | 37994476449, Medeiros, Joana Darc Freire de, 37643240400, Barbosa, Dayse Luna, 00074712462, Moreira, L?cio Fl?vio Ferreira |
| Publisher | PROGRAMA DE P?S-GRADUA??O EM ENGENHARIA SANIT?RIA, UFRN, Brasil |
| Source Sets | IBICT Brazilian ETDs |
| Language | Portuguese |
| Detected Language | English |
| Type | info:eu-repo/semantics/publishedVersion, info:eu-repo/semantics/masterThesis |
| Source | reponame:Repositório Institucional da UFRN, instname:Universidade Federal do Rio Grande do Norte, instacron:UFRN |
| Rights | info:eu-repo/semantics/openAccess |
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