The development of artesian and pumped wells as a source of irrigation water has created the need for a measuring device which will be accurate for small discharges. The thin edged weir has been accepted as one of the most accurate and desirable measuring devices for this work. Three types of weirs are now commonly used: the Rectangular, the Cipolleti, and the Triangular Notch weir. Of these types the triangular notch is probably the best suited for small discharges (under 3 second feet). The various formulae for discharge over 90% Triangular weirs have been accurately determined for heads over two tenths of a foot. It is the purpose of this investigation to determine the coefficients for use in the general formula for discharge resulting from heads under 0.3 foot.

Thesis. 1975. M.S.--Massachusetts Institute of Technology. Dept. of Meteorology. / Bibliography: leaf 34. / M.S.

Thesis (MEng)--University of Stellenbosch, 2001. / ENGLISH ABSTRACT: This report deals with the use of Doppler meters to measure flow velocities and hence discharges in streams. The Doppler meter measures the shift in frequency of an acoustic wave, which it emits and then becomes reflected by a moving particle. The reading is converted into a velocity by dividing the shifted frequency by a calibration constant. The particles that reflect the signal need to follow the flow sufficiently closely so that their velocity may be assumed equal to the flow velocity. A previous study on the use of the Doppler meter at a Crump weir (Du Toit and Venter, 1999) indicated that velocities measured with a Doppler meter showed a distinct relationship with recorded water levels. However, the wide scatter of the observed frequencies in this study, necessitated further tests on the use of the Doppler meter at measuring structures as well as calibration tests on the instrument in the hydraulic laboratory of the University of Stellenbosch. The mam objective of this investigation was to establish the relationship between measured Doppler velocities at a Crump weir and the approach velocities in the stream. The instrument was to be tested in both modular and non-modular flow ranges. In addition, the instrument had to be calibrated in the hydraulic laboratory under varying flow conditions, such as very low flow velocities and different sediment concentrations. The placement of the probe at different depths of the flow was also investigated to comment on the accuracy of the Doppler readings at these depths. The results of these tests should serve as guidelines for any additional tests required for use of this instrument in open channel discharge measurements. The Doppler meter used for this study was supplied and manufactured in Stellenbosch by Flotron, and is being marketed as DFM-P-067. It was calibrated in the laboratory in a channel with limited width and hence non-two-dimensional flow conditions. Conclusions were drawn on the calibration constant that was established. The calibration of the instrument requires the division of the cross-sectional flow area into a number of sub-divisions over which the flow was integrated. The calibration constant of 1460 established in this study differs by approximately 6 percent from the theoretical constant value of 1375. The sensitivity of the Doppler meter to different sediment concentrations was also investigated. For the instrument to read a shifted frequency, it is essential that suspended particles that follow the water movement sufficiently closely are present in the stream. It was observed that readings of the instrument in "sediment-free" water differed only by 3.6% from the readings taken in water containing sediments. The instrument was thus not very sensitive to different sediment concentrations. It was also found that the angle at which the probe was placed in the water had no effect on the accuracy of the observed Doppler velocity. It was furthermore found that the Doppler meter worked reliably at all depths, including levels very close to the channel floor and levels just below the water surface. One drawback of the apparatus was the minimum velocity that it can measure accurately. This minimum velocity of 0.046 mis does not compare well with that for other commercially available Doppler meters. The Argonaut-Acoustic Doppler meter for example can measure velocities as low as O.OOOlm/s, meaning that the DFM-P-067 measures a minimum velocity 460 times swifter than the minimum velocity of the Argonaut-Acoustic Doppler meter. After the Doppler meter had been calibrated, it was tested at a Crump weir in the laboratory to determine the relationship between the Doppler velocities, measured at the weir's crest, and the velocities in the approach channel. These tests were performed for both modular and non-modular flow conditions. The report concludes that, within the flow range in which the instrument was tested, there is a linear relationship between the two velocities mentioned. It is likely that the results obtained in the modular flow range can be used to extrapolate for high flows, especially for submergence ratios less than 0.93. The wide scatter of results obtained in the previous study was due to the readings not being averaged. The Doppler meter does not measure a point velocity but an average velocity within the acoustic field that it emits. This acoustic field is very small and depends on the geometry of the probe. Finally it is recommended that the linear relationship in the non-modular flow range be investigated further in a larger model, where the submergence ratio can be better controlled. The Doppler meter should in future also be calibrated in a wide channel in which two-dimensional flow conditions are approached and these results should be compared to the results obtained in this study. Every instrument is expected to have its own calibration constant, and depending on its application, it can either be calibrated at a weir or in the laboratory. The calibration of the instrument at a Crump weir should allow for a wider range of flows, and also very low flow velocities. At the end of this report guidelines were drawn up that are based on the results and conclusions obtained in this investigation. They may serve as an aid for measurements that could be carried out with this instrument in open channels. / AFRIKAANSE OPSOMMING: Hierdie verslag handeloor die gebruik van die Doppler-meter om vloeisnelhede en derhalwe die vloeitempos in riviere te meet. Die Doppler meter word gebruik om die verandering in die frekwensie van 'n akoustiese golf wat deur bewegende deeltjies in die water gereflekteer word te meet. Die lesing word dan omgeskakel in 'n snelheid deur die gewysigde frekwensie deur 'n kalibrasie konstante te deel. Die bewegende deeltjies wat die sein reflekteer, volg die vloei genoegsaam sodat aanvaar kan word dat hulle snelhede gelyk aan die vloeisnelheid is. 'n Vorige studie in die gebruik van die Doppler meter by 'n Crump meetwal het baie belowende resultate getoon deurdat daar gevind is dat die gemete Doppler snelheid 'n duidelike verwantskap toon met veranderings in gemete water vlakke. As gevolg van die wye band in die waargenome frekwensies in die studie is aanbeveel dat verdere toetse op die gebruik van die Doppler meter by meetstasies gedoen moet word. Die instrument moet ook in die laboratorium gekalibreer word. Die hoofdoel van hierdie ondersoek was om die verwantskap tussen die gemete Doppler snelhede by 'n Crump meetwal en die aankomssnelhede in die stroom te bepaal. Dit moes gedoen word in beide die modulêre en niemodulêre vloeibestekke. Behalwe vir die kalibrasie van die instrument in die laboratorium moes die betroubaarheid daarvan onder verskillende vloei toestande ook getoets word, soos byvoorbeeld by lae vloei snelhede en by verskillende sediment konsentrasies. Die instrument is ook op verskillende vlakke binne die vloei getoets om te bepaal of daar op hierdie vlakke betroubare lesings verwag kon word. Resultate verkry, kan dan dien as riglyne vir enige verdere toetse wat nog op die instrument in oop kanale uitgevoer moet word. Die Doppler meter wat vir die ondersoek gebruik is, word in Stellenbosch vervaardig deur Flotron en word onder die naam DFM-P-067 bemark. Dit is in die laboratorium in 'n kanaal met 'n beperkte breedte getoets en IS daarom in nie-twee dimensionele vloei gekalibreer. Gevolgtrekkings IS gebaseer op die kalibrasie konstante verkry uit die toetse. Die kalibrasie van die instrument vereis dat die deursnee area van die vloei in verskeie segmente onderverdeel moes word. Die kalibrasie konstante van 1460 bepaal in hierdie studie verskilongeveer 6% van die teoretiese waarde van 1375 vir die konstante. Die Doppler meter se sensitiwiteit vir verskillende sediment konsentrasies is ook ondersoek. Dit is noodsaaklik dat daar gesuspendeerde deeltjies teenwoordig in die water is en dat die deeltjies saam met die water beweeg om te verseker dat die instrument die gewysigde frekwensie kan registreer. Daar is egter gevind dat die lesings van die instrument in sediment-vrye water slegs met 3,6% verskil van lesings wat in water met sediment geneem is. Dit lei tot die gevolgtrekking dat die instrument nie baie sensitief vir veranderlike sediment konsentrasies in die water is nie. Daar is ook gevind dat die hoek waarteen die sender in die water geplaas word nie die akkuraatheid van die Doppler snelhede beinvloed nie. Verder is gevind dat die Doppler meter bevredigende resultate lewer, ongeag op watter diepte lesings geneem word. Tydens toetse is waarnemings baie nabyaan die kanaal bodem asook nabyaan die water se oppervlak gedoen. 'n Tekortkoming van hierdie instrument is die minimum snelheid wat dit akkuraat kan meet. Daar is gevind dat die Doppler meter se muurnum snelheid lesing van 0.046 mis nie goed vergelyk met dié van ander meters wat kommersieël beskikbaar is nie. Die Argonaut-Acoustic Doppler meter kan byvoorbeeld vloeisnelhede so laag as 0.0001 mis meet wat beteken dat die DFM-P-067 se minimum betroubare vloeisnelheid 460 keer vinniger is as die Argonaut-Acoustic Doppler meter se minimum betroubare vloeisnelheid. Nadat die Doppler meter gekalibreer is, is dit by 'n Crump meetwal in die laboratorium getoets om die verhouding tussen die Doppler snelhede gemeet by die oorloopkruin en die snelhede wat in die aanloopkanaal gemeet is, te bepaal. Hierdie toetse is uitgevoer op beide modulêre en nie-modulêre vloei toestande. Daar is gevind dat daar binne die vloeibestek waarin die toetse plaasgevind het 'n liniêere verband tussen die twee bogenoemde snelhede bestaan. Dit is hoogs waarskynlik dat die resultate wat in die modulêre vloeibestek gevind is gebruik kan word om vir hoë vloeie te ekstrapoleer, veral vir grade van versuiping laer as 0.93. Die vorige studie se uiteenlopende resultate kan toegeskryf word aan lesings waarvan die gemiddelde lesing vir 'n spesifieke vloeitoestand nie bepaal is nie. Die Doppler meter meet nie 'n bepaalde punt-snelheid nie, maar 'n gemiddelde snelheid binne die akoestiese veld wat dit uitstraal. Hierdie akoestiese veld is baie klein en afhanklik van die geometrie van die sender. Ten slotte word aanbeveel dat die lineêre verband in die nie-modulêre vloeibestek in 'n groter model, waar die graad van versuiping makliker beheerbaar is, verder ondersoek moet word. Die Doppler meter moet ook in 'n breë kanaal waarin twee dimensionale vloei voorkom, gekalibreer word. Resultate so verkry moet vergelyk word met die wat in hierdie studie behaal is. Elke instrument behoort sy eie kalibrasie konstante te hê en afhangende van waar dit gebruik word, kan dit of by 'n meetwal of in die laboratorium gekalibreer word. Die kalibrasie van die instrument by 'n Crump meetwal behoort 'n wyer reeks vloeie toe te laat met ook baie lae snelhede. Die verslag word afgesluit met riglyne gebaseer op die resultate en gevolgtrekkings wat uit die ondersoek voortgespruit het. Hierdie riglyne en gevolgtrekkings kan dan dien as 'n hulpmiddel vir metings wat met hierdie instrument in oop kanale uitgevoer word.

Thesis (Ph.D.(Civil Engineering))--University of the Witwatersrand, Faculty of Engineering, 1966.

Este trabalho propõe uma soleira assimétrica elíptica-circular com apenas dois pontos de descontinuidade, com parâmetros geométrico associados à vazão específica de projeto, com possibilidade de padronização e cujas características hidráulicas (linha d´água, pressões, coeficiente de vazão) podem ser determinadas teoricamente. Um sistema de equações diferenciais parciais permite o desenvolvimento de um modelo computacional para determinação dos valores teóricos dessas características. A validação dos valores teóricos das características hidráulicas da soleira por um modelo computacional foi realizada com a confrontação desses mesmos valores obtidos em um modelo físico, permitindo a comparação de pressões, linha d´água, coeficiente de vazão e profundidade crítica. / In this work is proposed an asymmetrical (elliptical-circular) weir with two points of discontinuity only, with geometrical parameters associated to the specific design discharge, allowing the standardization, and whose hydraulic characteristics (water profile, pressures and discharge coefficient) may be theoretically determinate. Their hydraulic characteristics, developed by a system of partial differential equations, system allowing the development of a computational model to determine the theoretical values of the weir hydraulic characteristics. The validation of these theoretical values of the weir hydraulic characteristics, obtained by a computational model, was made by the comparison between the values of water profile, pressures, discharge coefficient and critical depth obtained by the theoretical model and the values obtained by the physical model.

A soleira lateral desempenha um papel importante nos reservatórios de detenção/ retenção (off-line), atuando na captação das vazões afluentes e evitando possíveis enchentes, problema em destaque nos períodos chuvosos das principais capitais brasileiras. Um melhor entendimento do seu comportamento hidráulico possibilitará o desenvolvimento de estruturas laterais mais eficientes. O presente trabalho tem como objetivo criar um modelo da soleira lateral através da tecnologia CFD (Dinâmica dos Fluidos Computacional) e validá-lo através de experimentos em modelo reduzido do Laboratório de Hidráulica da Escola Politécnica da USP. A partir disso, explorar as características hidráulicas do modelo de CFD, como o comportamento dos níveis dágua e a distribuição de velocidades. No estudo da validação estudaram-se três tipos de refinamento de malhas e três modelos de turbulência (k-, k- (RNG) e SST k-). O modelo computacional validado é composto pela malha 3, com um refinamento cerca de 342000 elementos (hexaédricos predominante), e o modelo de turbulência k- (RNG), que apresentaram a maior precisão dos resultados. A análise da distribuição de velocidades possibilitou visualizar uma região de mínima velocidade abaixo da soleira lateral, e também quantificar uma região de baixas velocidades no início da soleira, onde é pequena a eficiência das vazões escoadas. Através do comportamento da superfície dágua foi possível visualizar a região de influência do dispositivo lateral no canal principal. A comparação do coeficiente de descarga do modelo de CFD com trabalhos de outros pesquisadores, um nacional e outro internacional, mostrou a representatividade do modelo criado para condições diferentes. A ferramenta CFD é promissora para o estudo de estruturas hidráulicas, contribuindo para o seu desenvolvimento e aperfeiçoamento. / The side weir plays an important role in the detention / retention tanks (off-line), operating in the uptake of water inflow and preventing possible flooding, which is a highlighted problem on rainy periods of the main Brazilian capitals. A better understanding of the hydraulic behavior allows the development of more efficient lateral structures. This work aims at creating a model of the side weir through CFD technology (Computational Fluid Dynamics) and validating it through experiments on a reduced model of the Laboratório de Hidráulica da Escola Politécnica da USP. Thereafter, explore the hydraulic characteristics of the CFD model, like the behavior of water levels and the velocity distribution. In the validation study, three types of mesh refinement and three turbulence models were studied (k-, k- (RNG) and SST k-). The computational model is validated by the composite mesh 3 with a refinement about 342,000 elements (hexahedral predominant), and the turbulence model k- (RNG), which had the highest precision of results. Analysis of the velocities distribution allowed us to visualize a region of minimum velocity below the side weir, and also to quantify a region of low velocities at the beginning of the weir, where the efficiency of overflows is small. Through water surface behavior it was possible to visualize the influence region of the side device in the main channel. A comparison of discharge coefficient of the CFD model between other works (one national and the other one international) showed the representativeness of the model created for different conditions. The CFD is a promising tool for the study of hydraulic structures, contributing to its development and improvement.

Este trabalho propõe uma soleira assimétrica elíptica-circular com apenas dois pontos de descontinuidade, com parâmetros geométrico associados à vazão específica de projeto, com possibilidade de padronização e cujas características hidráulicas (linha d´água, pressões, coeficiente de vazão) podem ser determinadas teoricamente. Um sistema de equações diferenciais parciais permite o desenvolvimento de um modelo computacional para determinação dos valores teóricos dessas características. A validação dos valores teóricos das características hidráulicas da soleira por um modelo computacional foi realizada com a confrontação desses mesmos valores obtidos em um modelo físico, permitindo a comparação de pressões, linha d´água, coeficiente de vazão e profundidade crítica. / In this work is proposed an asymmetrical (elliptical-circular) weir with two points of discontinuity only, with geometrical parameters associated to the specific design discharge, allowing the standardization, and whose hydraulic characteristics (water profile, pressures and discharge coefficient) may be theoretically determinate. Their hydraulic characteristics, developed by a system of partial differential equations, system allowing the development of a computational model to determine the theoretical values of the weir hydraulic characteristics. The validation of these theoretical values of the weir hydraulic characteristics, obtained by a computational model, was made by the comparison between the values of water profile, pressures, discharge coefficient and critical depth obtained by the theoretical model and the values obtained by the physical model.

In recent years, the general interest in the safety of dams and reservoirs has grown appreciably. This research describes the application and design of labyrinth weirs to improve the performance of existing reservoirs and also to be used for the construction of new dams. The parameters that can affect the performance of labyrinth weirs are discussed. Tests were conducted on normal linear weirs with four different crest shapes to determine the rate of change of discharge coefficient when each type of weir is used. It is found that weirs with rounded-crest shape can pass more flow than other types of weirs when they are subjected to the same total operating head. Two design charts are developed for labyrinth weirs with rounded-crest shape with HT/P ratio ranges from 0.15 to 0.5 and 0.5 to 1.0. The areas of application of labyrinth weirs, design procedure, different cases of design, and a design example are given. In addition, the performance of labyrinth weirs when the structure placed in an angle to the approaching flow (inclined labyrinth weirs) was tested.

Made available in DSpace on 2014-06-11T19:35:41Z (GMT). No. of bitstreams: 0 Previous issue date: 2012-06-04Bitstream added on 2014-06-13T19:05:52Z : No. of bitstreams: 1 hoffmann_p_dr_botib.pdf: 1460856 bytes, checksum: f067ccec9160ccbd165f626114c30a8f (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O objetivo deste capítulo foi determinar a distribuição temporal de Cladocera na Lagoa do Camargo, lateral ao Rio Paranapanema em sua zona de desembocadura no Reservatório de Jurumirim, analisando a flutuação da composição, abundância e diversidade da comunidade e sua relação com fatores ambientais. Quinzenalmente, entre junho de 2008 e maio de 2009, foram coletadas amostras de zooplâncton, por meio de arrastos verticais com rede cônica (malha de 50μm), e estimados parâmetros ambientais, em três estações de amostragem. Com o intuito de indicar possíveis diferenças significativas entre as amostragens das medidas dos fatores ambientais, e da abundância das principais espécies de Cladocera, foi utilizado o teste de Kruskal-Wallis complementado pelo teste de Student-Newman-Keuls (para α=5%). Uma Análise de Componentes Principais (ACP) foi aplicada, objetivando-se verificar possíveis semelhanças no comportamento das variáveis ambientais ao longo do período de amostragem. A fim de detectar os fatores ambientais que influenciam na abundância das espécies, foi realizada uma Análise de Correspondência Canônica (ACC). A relação entre as variáveis ambientais e abundâncias das principais espécies foi determinada com a Análise de Correlação de Spearman (para α=5%). Foi possível verificar os efeitos da variação hidrológica na distribuição temporal de Cladocera na Lagoa do Camargo no que se refere ao comportamento dos atributos da comunidade bem como da abundância absoluta e relativa das principais espécies. O período seco foi caracterizado pela manutenção de maiores valores de nível fluviométrico, profundidade e volume da lagoa. A entrada de água do rio provocou a remoção da fauna associada às macrófitas, promovendo o incremento da riqueza de Cladocera. O aumento da precipitação pluviométrica, no período... / The aim of this chapter was to determine the temporal distribution of Cladocera at the Camargo Lake, located next to the Paranapanema River within its mouth zone at the Jurumirim Reservoir, by analyzing the variation in the composition, abundance and diversity and how it relates to the environmental factors. On every two weeks between June, 2008 and May, 2009 samples of zooplankton were collected by means of vertical hauls with a conical net (50 μm mesh size), and a number of environmental parameters were estimated at three different sampling sites. In order to determine potential significant differences of environmental factors and abundance of Cladocera species amongst sampling sets the Kruskal-Wallis test was employed in tandem with the Student-Newman-Keuls test (α=5%). Principal Components Analysis (PCA) was performed to verify potential similarities in the variation of the environmental factors across all of the collected sample sets. Canonical Correspondence Analysis (CCA) was performed to determine the environmental factors that influenced the abundance of Cladocera species. The relationship between environmental factors and the abundance of species was determined with Spearman Correlation Analysis (α=5%). It was verified that the hidrological variation affected the temporal distribution of Cladocera at the Camargo Lake in terms of community attributes as well as the total and relative abundance of species. The dry period had the greatest values as far as river water levels as well as depth and volume of the lake. The river water influx washed off the fauna associated with the macrophytes causing an increase in Cladocera richness. Increased rain levels led to a higher concentration of suspension matter and phosphorus, which caused a reduced abundance of Cladocera and also caused the replacement... (Complete abstract click electronic access below)

Orientador: Raoul Henry / Coorientador: Maria Stela Maioli Castilho Noll / Banca: Lourdes Maria Abdu El-Moor Loureiro / Banca: Eliana Aparecida Panarelli / Banca: Maria José dos Santos Wisniewski / Banca: Paulina Maria Maia Barbosa / Resumo: O objetivo deste capítulo foi determinar a distribuição temporal de Cladocera na Lagoa do Camargo, lateral ao Rio Paranapanema em sua zona de desembocadura no Reservatório de Jurumirim, analisando a flutuação da composição, abundância e diversidade da comunidade e sua relação com fatores ambientais. Quinzenalmente, entre junho de 2008 e maio de 2009, foram coletadas amostras de zooplâncton, por meio de arrastos verticais com rede cônica (malha de 50μm), e estimados parâmetros ambientais, em três estações de amostragem. Com o intuito de indicar possíveis diferenças significativas entre as amostragens das medidas dos fatores ambientais, e da abundância das principais espécies de Cladocera, foi utilizado o teste de Kruskal-Wallis complementado pelo teste de Student-Newman-Keuls (para α=5%). Uma Análise de Componentes Principais (ACP) foi aplicada, objetivando-se verificar possíveis semelhanças no comportamento das variáveis ambientais ao longo do período de amostragem. A fim de detectar os fatores ambientais que influenciam na abundância das espécies, foi realizada uma Análise de Correspondência Canônica (ACC). A relação entre as variáveis ambientais e abundâncias das principais espécies foi determinada com a Análise de Correlação de Spearman (para α=5%). Foi possível verificar os efeitos da variação hidrológica na distribuição temporal de Cladocera na Lagoa do Camargo no que se refere ao comportamento dos atributos da comunidade bem como da abundância absoluta e relativa das principais espécies. O período seco foi caracterizado pela manutenção de maiores valores de nível fluviométrico, profundidade e volume da lagoa. A entrada de água do rio provocou a remoção da fauna associada às macrófitas, promovendo o incremento da riqueza de Cladocera. O aumento da precipitação pluviométrica, no período... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The aim of this chapter was to determine the temporal distribution of Cladocera at the Camargo Lake, located next to the Paranapanema River within its mouth zone at the Jurumirim Reservoir, by analyzing the variation in the composition, abundance and diversity and how it relates to the environmental factors. On every two weeks between June, 2008 and May, 2009 samples of zooplankton were collected by means of vertical hauls with a conical net (50 μm mesh size), and a number of environmental parameters were estimated at three different sampling sites. In order to determine potential significant differences of environmental factors and abundance of Cladocera species amongst sampling sets the Kruskal-Wallis test was employed in tandem with the Student-Newman-Keuls test (α=5%). Principal Components Analysis (PCA) was performed to verify potential similarities in the variation of the environmental factors across all of the collected sample sets. Canonical Correspondence Analysis (CCA) was performed to determine the environmental factors that influenced the abundance of Cladocera species. The relationship between environmental factors and the abundance of species was determined with Spearman Correlation Analysis (α=5%). It was verified that the hidrological variation affected the temporal distribution of Cladocera at the Camargo Lake in terms of community attributes as well as the total and relative abundance of species. The dry period had the greatest values as far as river water levels as well as depth and volume of the lake. The river water influx washed off the fauna associated with the macrophytes causing an increase in Cladocera richness. Increased rain levels led to a higher concentration of suspension matter and phosphorus, which caused a reduced abundance of Cladocera and also caused the replacement... (Complete abstract click electronic access below) / Doutor