Dissertations / Theses on the topic 'Weirs'

This thesis describes a short study to examine the behaviour of submerged flow over a thin plate weir with differing upstream and downstream bed levels i.e. an unequal bed weir as opposed to an equal bed weir where the upstream and downstream beds are at the same level. As submerged weir flow is a function of downstream conditions, it was thought that a lower downstream bed would make submerged flow over the weir easier, This is turn suggested that; The shape of the upstream head (Hu) vs downstream head (Hd) graph would change, being initially more steep in the unequal bed case. The Froude Number of the approaching flow would be lower for the unequal bed weir than for an equal bed weir at the same submergence. Using one of the existing submerged flow formula would lead to an erroneous calculated value. A series of measurements was done on two model weirs of different sizes subject to successive levels of submergence. Analysis of the readings of upstream and downstream heads indicated that the difference in bed levels was significant and the three effects above were noted. The work also suggested a new form of equation to calculate flow over a submerged weir. This was looked at briefly.

Labyrinth weirs are often a favorable design option to regulate upstream water elevations and increase flow capacity; nevertheless, it can be difficult to engineer an optimal design due to the complex flow characteristics and the many geometric design variables of labyrinth weirs. This study was conducted to improve labyrinth weir design and analyses techniques using physical-model-based data sets from this and previous studies and by compiling published design methodologies and labyrinth weir information. A method for the hydraulic design and analyses of labyrinth weirs is presented. Discharge coefficient data for quarter-round and half-round labyrinth weirs are offered for sidewall angles of 6° to 35°. Cycle efficiency is also introduced to aid in sidewall angle selection. Parameters and hydraulic conditions that affect flow performance are discussed. The validity of this method is presented by comparing predicted results to data from previously published labyrinth weir studies. A standard geometric design layout for arced labyrinth weirs is presented. Insights and comparisons in hydraulic performance of half-round, trapezoidal, 6° and 12° sidewall angles, labyrinth weir spillways located in a reservoir with the following orientations are presented: Normal, Inverse, Projecting, Flush, Rounded Inlet, and Arced cycle configuration. Discharge coefficients and rating curves as a function of HT/P are offered. Finally, approaching flow conditions and geometric similitude are discussed; hydraulic design tools are recommended to be used in conjunction with the hydraulic design and analysis method. Nappe aeration conditions for trapezoidal labyrinth weirs on a horizontal apron with quarter- and half-round crests (sidewall angles of 6° to 35°) are presented as a design tool. This includes specified HT/P ranges, associated hydraulic behaviors, and nappe instability phenomena. The effects of artificial aeration (a vented nappe) and aeration devices (vents and nappe breakers) on discharge capacity are also presented. Nappe interference for labyrinth weirs is defined; the effects of nappe interference on the discharge capacity of a labyrinth weir cycle are discussed, including the parameterization of nappe interference regions to be used in labyrinth weir design. Finally, the applicability of techniques developed for quantifying nappe interference of sharp-crested corner weirs is examined.

Tyrolean type water-intake structures are widely used on mountain rivers to provide water to hydropower stations. The main concern encountered in these kinds of structures is the amount of water diverted from the main channel and sediment carried by this flow. The diverted flow should not be less than the design discharge of the hydropower station and the amount of the sediment entering the hydraulic system should be minimum. In this study a physical model of a Tyrolean weir was constructed at the Hydromechanics Laboratory and by varying the dimensions of the various components of this system<br>the length, the inclination angle of the rack and the distance between the rack bars, the amount of water and sediment entering the system were measured for a wide range of discharges. The experiments were conducted in two stages. In the first stage the tests were made with only water, and in the second stage, water and sediment having different gradation were used. Applying dimensional analysis to the related parameters of the system dimensionless terms were defined for water capture efficiency and discharge coefficient of the system, and their variations with the relevant parameters were plotted. Using these diagrams one can determine the amount of water to be diverted by a Tyrolean weir of known geometry and main channel flow.

Rock weirs are small dam-like structures composed of large loose rock commonly found in ecological engineering design. By appearing more natural than concrete structures, rock weirs are preferred for use as hydraulic control structures in river engineering, stormwater management, and constructed wetlands. Rock weirs increase hydraulic head upstream, and facilitate fish passage, channel stabilization, floodplain reconnection, and in-stream habitat creation. When used in constructed wetlands, rock weirs play a valuable role in developing appropriate wetland hydrology. Although rock weirs are commonly used, a deficit of knowledge exists relating to the stage-discharge relationship of these structures. Therefore, the goal of this research was to determine a weir equation and corresponding discharge coefficients that improve predictions of flow through rock weirs. A flume study was conducted to develop a rock weir equation and discharge coefficients. Scaled model rock weirs were tested in a 1 m x 8 m x 0.4 m recirculating flume. Rock weirs varied by length (0.152 m, 0.305 m, and 0.457 m), depth (0.152 m and 0.305 m), and minimum rock diameter (12.7 mm, 19.1 mm, 25.4 mm). Three channel slopes were used (0%, 0.5%, 1%), and the flume discharge was varied for five water stages for each rock weir. Buckingham Pi analysis was used to develop seven dimensionless parameters. Regression analyses were then used to develop a model for discharge and the discharge coefficient. Results showed that weir length and depth play a significant role in predicting the discharge coefficient of rock weirs.<br>Master of Science<br>Rock weirs are small dam-like structures composed of large loose rock; by appearing more natural, they are preferred for use in river engineering, stormwater management, and constructed wetlands. Rock weirs increase upstream water depth, improving fish passage, channel stabilization, floodplain reconnection, and in-stream habitat creation. When used in design of constructed wetlands, rock weirs are used to establish the necessary water depths for a given type of wetland. Although rock weirs are commonly used in engineering design, there are no equations to predict water velocity or flow rate across these structures. Therefore, the goal of this research was to determine a weir equation that improves predictions of flow through rock weirs. A flume study was conducted to develop a rock weir equation. Miniature rock weirs were tested in a 1 m x 8 m x 0.4 m recirculating laboratory channel. Rock weirs varied by length (0.152 m, 0.305 m, and 0.457 m), depth (0.152 m and 0.305 m), and minimum rock diameter (12.7 mm, 19.1 mm, 25.4 mm). Three channel slopes were used (0%, 0.5%, 1%), and the water flow rate was varied for five water depths for each rock weir. Statistical analyses were conducted to determine an equation that predicts water flow through rock weirs for use in engineering design. Results showed that weir length and depth played a significant role in predicting water flow through rock weirs.

Oblique weirs are those weirs placed at an angle with respect to the channel centerline. They can be used in canal applications where more discharge is needed, but there is limited freeboard. The discharge coefficients were determined for 54 different weirs by measuring total head for various flows over each weir. These weirs included sharp, half round and quarter-round-crested weirs. There were 18 weirs for each crest shape with three weir heights for each angle tested. The oblique angles tested were 10°, 15°, 25°, 45°, 60°, and 90° with respect to the channel centerline, with the nominal weir heights being 4, 8, and 12 inches. The half-round-crested weirs were the most efficient, followed by the quarter-round-crested weirs and the sharp-crested weirs were the least efficient. By decreasing the oblique angle, the weir length became longer and the weir would be more efficient than the normal weir.

The need to accommodate larger reservoir discharge events has prompted the improvement or replacement of existing spillways. One possible spillway modification is the use of an in-reservoir arced labyrinth weir in place of a linear weir. Arced labyrinth weirs can increase crest length (more cycles) and have improved hydraulic efficiency in non-channelized approach flow applications, compared to traditional labyrinth weir applications. In this study, arced labyrinth weir flow characteristics were observed for eleven different laboratory-scale model geometries at the Utah Water Research Laboratory. Rating (Cd vs. HT/P) data and observations were recorded for each configuration, and discharge efficiency was determined. Cycle efficiency, which is representative of the discharge per cycle, was also reported.

In recent years, magnitudes of flood estimates used in hydraulic design have increased for many reservoirs. Consequently, many existing spillways are now deficient as they do not meet current discharge capacity requirements. To rehabilitate existing, fixed-width spillways, labyrinth weirs are often viable solutions. For reservoir applications, arcing labyrinth weirs into the reservoir increases hydraulic efficiency. This results from better cycle orientation to the approaching flow field. This study supplements available arced labyrinth weir hydraulic data by observing flow characteristics of three laboratory-scale physical models and two numerical (CFD) models. Physical model results provide head (energy)-discharge data and empirical coefficients for hydraulic design. Results also show that increasing the arc angle improves efficiency at H/P<0.3, where H/P is upstream piezometric head divided by weir height; after which, efficiency improvements diminish as downstream submergence also increases. The purpose of the CFD analysis was to assess the appropriateness of CFD as a design tool for arced labyrinth weir head-discharge relationship development. The CFD model results found good agreement with the physical model data indicating CFD’s usefulness as a hydraulic design tool; however, it is recommended that CFD models be calibrated to reliable laboratory or field data. This study’s data may be used, with sound engineering judgement, to aid in hydraulic design of arced labyrinth weirs

Dams and weirs are widely implicated in large-scale declines in both the range and abundance of aquatic fauna. Although many factors are involved, such declines are commonly attributed to the prevention or reduction of migration, reductions in available habitat, alteration of natural flow regimes and changes to physicochemical characteristics. In Australia, studies into the ecological effects of these impacts are limited, and have concentrated mainly on species of recreational and commercial importance. Subsequently, the adverse effects of dams and weirs, and suitable methods of mitigation, remain largely unknown for many other taxa. Therefore, the major aim of this thesis is to investigate the ecological effects of dam and weir construction on previously unstudied migratory assemblages of fish and macroinvertebrates in the Murray-Darling Basin. It is anticipated that the results of these studies will feed back into improved management strategies that help arrest the previously observed declines of aquatic fauna. Initially, fish communities were sampled, by boat electrofishing, from both reference sites and downstream of Balranald and Redbank weirs on the lower reaches of the Murrumbidgee River, Australia. Sampling was stratified over large spatial and temporal scales to gain a comprehensive understanding of species most affected by the presence of these two barriers. In general, the weirs obstructed fish migrations during summer and autumn and many species of small-bodied fish such as Australian smelt, western carp gudgeon, fly-specked hardyhead and crimson-spotted rainbowfish accumulated downstream of Balranald Weir. In addition, downstream accumulations of juveniles of larger-bodied species such as bony herring, common carp and goldfish were also detected. Although many previous studies had either documented or hypothesised that upstream migrating fish accumulate downstream of migration barriers, none attempted to quantify the size of such populations. Therefore, a simple but efficient method to estimate the size of migratory populations was assessed at the Balranald Weir site. The application of two commonly used estimation techniques yielded relatively reliable results for seven species that accumulated downstream of the weir. Population size estimates were greatest for most species during summer and autumn, where accumulations as high as 800 fish per day were detected. The largest calculated population size estimates, in addition to the greatest temporal variation, of any individual species was observed in bony herring. Given the simplicity of the technique and the relative accuracy of population estimates, it was concluded that these methods could easily be applied to other weirs where the size of migratory populations is of particular interest. A study investigating the effects of Yanco Weir on the diets of three migratory percichthyid species, Murray cod, trout cod and golden perch was also conducted. Observed spatial variation in a number of trophic processes strongly implicated Yanco Weir as a major contributor to increased competition among percichthyid species on the Murrumbidgee River. The greater relative abundance of percichthyids from downstream samples, combined with increases in dietary overlap and a greater percentage of empty stomachs, also suggested percichthyids may be significantly affecting the relative abundance of potential prey items such as freshwater prawns and Australian smelt. These significant changes in dietary composition were likely related to migratory behaviour, as these species accumulated downstream of the weir, and could be readily expected at other sites where passage is obstructed. It was suggested that the construction of suitable fish passage facilities would effectively reduce the probability of migratory fish accumulating and, subsequently, potential effects of dams and weirs on trophic processes. Since it was established that dams and weirs of the Murrumbidgee River were significantly affecting migratory fish communities, an innovative but relatively inexpensive fishway design, the Deelder fish lock (after Deelder, 1958), was constructed and assessed for wider application throughout the Murray-Darling Basin. The Deelder lock was effective at mitigating the effects of Balranald Weir by providing passage for a wide range of size classes and species of fish; but importantly, the structure enabled the passage of most species previously observed to accumulate downstream of the structure. Most significant was the ability of the fish lock to pass substantial numbers of small-bodied fish, which were previously not considered migratory, suggesting that these species should be considered when developing options to mitigate the effects of other dams and weirs throughout the Murray-Darling Basin. A significant finding of this study was the realisation that substantially more species and size classes of Australian native fish are migratory than previously thought. Subsequently, it is recommended that, when designing facilities to mitigate the effects of a dam or weir, the structure of the entire migratory community is considered when developing operating parameters. Various options for mitigating the effects of dams and weirs are discussed, but it was concluded that the construction of effective fishways would be the most appropriate means of restoring migration pathways to Australian native fish. A strategic approach for assessing and adaptively mitigating the effects of dams and weirs is presented and discussed.

Sharp crested rectangular weirs used for discharge measurement purposes in open channel hydraulics are investigated experimentally. A series of experiments were conducted by measuring discharge and head over the weir for different weir heights for full width weir. It is seen that after a certain weir height, head and discharge relation does not change. Hence a constant weir height is determined. For that height<br>discharge and head over the weir are measured for variable weir width, starting from the full width weir to slit weir. Description of the discharge coefficient valid for the full range of weir widths and an empirical expression involving dimensionless flow variables is aimed. Experimental data obtained for this purpose and the results of the regression analysis performed are represented.

This study is an experimental research to formulate the discharge over sharp-crested rectangular weirs. Firstly, a series of measurements on different weir heights were conducted to find the minimum weir height for which channel bed friction has no effect on discharge capacity. After determining the appropriate weir height, weir width was reduced to collect data on discharge-water head over weir relationship for a variety of different weir openings. Then, the data was analyzed through regression analysis along with utilization of global optimization technique to reach the desired formulation for the discharge. By taking advantage of a newly-introduced &ldquo<br>weir velocity&rdquo<br>concept, a simple function was eventually detected for the discharge where no discharge coefficient was involved. The behavior of the weir velocity function obtained in the present study illustrates the transition between the fully contracted and partially contracted weirs. In addition, the proposed weir velocity formulation is simple and robust to calculate the discharge for full range of weir widths.

Much work has been published regarding discharge coefficients for various weir structures. What has not been published to the same extent are the effects of model scale associated with the weirs being studied. If laboratory weirs are too small, scale effects can affect the magnitude of the discharge coefficient. These errors may be significant if the weir serves as a control structure for an emergency spillway. It is imperative that discharge be accurately predicted to enable safe design and operation. Numerical and physical means were employed to analyze the effects of scale associated with Froude Modeling of weirs with sharp and flat crests. An inverse formulation for the ideal flow of water over a weir was developed. The formulation appeared to be sound; however, the numerical method failed because the boundary condition on the free surface had multiple roots, which were almost equal in magnitude and sign. Laboratory data were collected and analyzed to determine the existence of scale effects and the flow conditions under which they were manifested. Results indicate that scale effects are present even with relatively large model sizes (12 inches high with a crest thickness of 24 inches). The scale effects appear to be associated with the size of the weir-wall and the viscosity. Although the viscosity was not altered, the results show a characteristic Reynolds Number for a given crest thickness-to-height ratio where scale effects cease to exist for increasing total head. Several graphs defining the conditions where scale effects exist for a given weir size were developed. Use of the graphs allows one to determine the minimum total head (piezometric plus velocity head) that one may operate a given size of weir or size a weir given the minimum total head to be tested to avoid scale effects. A design curve for discharge coefficients was developed to be used for determining the capacity of prototype weirs. The curve can be used to determine the discharge coefficient for new or existing hydraulic control structures.

In recent years there has increased interest in low head ‘on weir’ hydro across the UK. This directly corresponds to carbon reduction targets, renewable energy targets and financial incentives directed at renewable energy generating schemes. Despite increased interests, current understandings of the aquatic implications of low head ‘on weir’ hydro are unclear and not one in field investigation has been carried out at an existing scheme. Yet with important environmental legislation preventing the deterioration of ecological river quality, mainly the Water Framework Directive (WFD), there is an urgent need to improve current understandings. Fundamentally low head ‘on weir’ hydropower is a human activity that could potentially alter the aquatic environment, change natural biotic communities and cause failure to comply with WFD targets. On the other hand, as low head ‘on weir’ schemes are fitted on existing weirs which have already potentially altered the aquatic environment, there is the chance that adding a hydro scheme to a weir could in fact improve the aquatic environment and provide benefits for ecology whilst also providing meaningful amounts of electricity (EA, 2010). The overarching aim of this project was to advance the understanding of how low head ‘on weir’ hydropower can influence physical and chemical habitat condition and the phytobenthic biofilm. In order to achieve the aim, this thesis also investigated how weirs themselves change physical and chemical riverine conditions and the phytobenthic biofilm. To investigate the influence of an existing low head weir on the phytobenthic biofilm comparisons were made between the tail riffle below an existing obsolete weir and riffles upstream and downstream of the weir over time. This design was also replicated for a low head ‘on weir’ hydro scheme. Large scale and small scale spatial surveys were also conducted to explore finer scale spatial patterns below the scheme. There was evidence across this study to suggest that low head ‘on weir’ hydropower is having minimal effects of phytobenthic biomass and community composition. Moreover changes in biomass and community composition were more obvious over time than spatially across sampling locations. There was also evidence to suggest that low head ‘on weir’ hydro schemes can mask the effects of weirs by reducing the proportion of flow over the weir.

Abstract Fishways are hydraulic structures designed to dissipate the energy of flowing water in order to decrease water velocities and increase water depths. The history of fishways is long, the first written remarks date back to the 17th century. Fishway hydraulics, however, have been intensively studied only starting since the 1980's. Fishways have been classified into three main categories according to their hydraulic characteristics: pool-and-weir, vertical slot, and Denil fishways. Fishways are hydraulically complex structures, and thus designing tools for different fishway types have been developed. In this report, a new designing procedure has been established, and equations for each main fishway type have been suggested. In addition, flow conditions below different fishway types have been examined, and velocity distributions at weirs with V-shaped crests in both pool-and-weir fishways and at a single weir have been compared in different discharges and drops. Fishway flows have been compared with flows over single weirs.

Aeration is the process of increasing the dissolved oxygen content of water, which is an important water quality parameter for the survival of flora and fauna on this planet. The dissolved oxygen level can be increased using hydraulic structures or by installing mechanical aerators. Hydraulic structures proved to be an economical and efficient way of enhancing the aeration process, thereby increasing the dissolved oxygen in the water stream. It develops large amounts of air bubbles; as a result, contact surface area increases, and hence the water-air -mass transfer accelerates. Weirs are having the highest aeration efficiency among all hydraulic structures. Various researchers study the aeration process involved in weirs and various experiments have been done to study the parameters involved. As literature said that the aeration efficiency of the different hydraulic structures depends on their geometry. According to past studies, the researchers have stated that the hydraulic structures help enhance the dissolved oxygen of the water body. Rivers clean themselves naturally after movement over a certain distance by the process of aeration. It is also known as the self-cleaning nature of rivers. Weirs also follow the same process for cleaning as well as maintaining the various water quality parameters. They function in the same manner as rivers naturally perform the self-cleansing process for its purification. In the self-cleansing process, the river clears itself and maintains various water quality parameters. In order to enhance the DO content of the water body (river, dams, and reservoirs), an experimental study was conducted in Fluid Mechanics and Hydraulic Laboratory at the Delhi Technological University. The primary goal of this research was to increase the DO content of the water body through aeration. The author conducted an experimental study over three different types (Type-A, Type-B, and Type-C) of Piano Key Wier models and compared them to achieve this goal. The present study's findings conclude that the aeration of the free-flowing water can be enhanced by constructing hydraulic structures across the stream or river.

This thesis is devoted to the study and designs of two important proportional weirs having the discharge-head characteristics of Q α H 2/3 In the first design a geometrically simple weir in the form of a rectangular weir over a inverted V-notch (Chimney weir) is presented. This weir gives for all flows above a threshold depth a discharge proportional to H 2/3 within a maximum percentage error of ±1.5, (measured above a reference plane) within certain limits of head. Second design is concerned with the self-basing weir in which a portion of the weir above the crest acts as a base. This design is achieved by using the complementary weir profile of a Quadratic weir above the parabolic base which has the significant property of fast convergence. This weir gives discharge for all flows above the threshold depth, proportional to (head)2/3 measured above a reference plane, with increasing accuracy as head increases. Experiments with these two weirs confirm the theory by giving a constant average Coefficient of Discharge (Cd) of 0.62. The importance of these weirs as a sensitive discharge measuring device in field and laboratory is highlighted.

This thesis is devoted to the study and designs of two important proportional weirs having the discharge-head characteristics of Q α H 2/3 In the first design a geometrically simple weir in the form of a rectangular weir over a inverted V-notch (Chimney weir) is presented. This weir gives for all flows above a threshold depth a discharge proportional to H 2/3 within a maximum percentage error of ±1.5, (measured above a reference plane) within certain limits of head. Second design is concerned with the self-basing weir in which a portion of the weir above the crest acts as a base. This design is achieved by using the complementary weir profile of a Quadratic weir above the parabolic base which has the significant property of fast convergence. This weir gives discharge for all flows above the threshold depth, proportional to (head)2/3 measured above a reference plane, with increasing accuracy as head increases. Experiments with these two weirs confirm the theory by giving a constant average Coefficient of Discharge (Cd) of 0.62. The importance of these weirs as a sensitive discharge measuring device in field and laboratory is highlighted.

A diversion weir is a headwork facility built across a river to raise the water level and to divert water for various purposes, such as irrigation, hydropower generation, etc. Diversion weirs with sidewise intakes are widely used in plain rivers. They are composed of many structural components which are designed for different purposes. In this thesis, a Windows-based, visual, user friendly program named WINDWEIR was developed in Visual Basic.NET programming language for the optimum design of a diversion weir with sidewise intake. It determines the overall dimensions of each of the components of the diversion weir and the total cost of the whole structure. It also performs stability analysis. It is such a flexible computer program that a design engineer can assess various dimensions of the structure from viewpoints of safety and economy by performing quick successive test runs to achieve an optimum solution among various alternatives.

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.<br>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.

Tyrolean type water-intake structures are commonly used on mountain rivers to supply water to hydropower stations. The amount of water to be diverted from the main channel is the major concern in these kind of structures and should not be less than the design discharge. In this study a physical model of a Tyrolean type water-intake structure was built at the laboratory and the diverted flow from the main channel through the intake structure having steel racks and perforated plates of different types were measured. The experiments were conducted in two stages. In the first stage the tests were carried out with only steel racks having three different bar openings and slopes, and in the second stage, perforated screens of three different circular openings and screen slopes were used. Applying dimensional analysis to the related parameters of the system the dimensionless terms were defined for the water capture efficiency and discharge coefficient of the system, and their variations with the relevant parameters were plotted. Using these diagrams one can determine the amount of water to be diverted by a Tyrolean weir of known geometry and main channel discharge.

Dissertation (PhD)--Stellenbosch University, 1996.<br>One copy microfiche.<br>Some digitised pages may appear illegible due to the condition of the original microfiche.<br>ENGLISH ABSTRACT: The present network of now gauging stations in South Africa has grown from isolated observations on an ad extensive is to an extensive network of stations across the country. Standardised gauging stations to suit local conditions have been developed which include purposely desigll4:d compound weirs. Nearly all. compound gauging weirs In South Africa have. for practical reasons. been constructed without dividing walls. thus deviating lr',:.n the standards set by the British Standards Institution (1981). Uncertainty about the accuracy of calibration of such structures had to be darifi,ed and. where ~cessary. adjustments had to be made to existing calibration formulae in order to compensate for the de,,·iations. It was also necessary to determine whether the accuracies that could be attained were adequate in terms of the potential financial implications of inaccuracies. It has thus become necessary to re-evaluate the calibration of these structures which consist of mainly compound Crump .md sharp-crested weirs. Selected flow l"t'Cords were analysed and the data wa.\ used to determine the impact of errors on the required capacities of reservoirs. This wa., done in an anempt to provide guidelines for the accuracy required in flow records. An31ysing a single application of a flow record cannot provide guidelines for the required accuracy of a flow record and thus the gauging of flow. Although no general conclusions can be drawn. it appears thal the benefits arising from an improvement in the accuracy of a flow record are proportionally greater than the percentage improvement in accuracy. Three-dimensional flow conditions exist either upstream or downstream of the point of stage measurement depending on the presence or absence of diViding walls at a compound gauging weir. The existing calibro1tion theory does not account for the influences of three-dimensional flow conditions and a.-'isociatcd energy losses in the determination of the upstream total energy head. Hydraulic model tests were thus undenaken to detemline the magnitude of the resulting energy losses. New techniques were developed to compensate for these energy losses in the calibration theory of compound gauging weirs. Application of the new calculation techniques to rate compound weirs using a single point of stage measurement results in improvements in accuracy. It was found that compound weirs without dividing walls can be rated to greater levels of accuracy than weirs with dividing walls, where stage measurements are taken at a single point<br>AFRIKAANSE OPSOMMING: Die huidige nc!werk van vloclmectpumc III SUld-Afnka hel gegroei van gc'isoleerde waamemings op 'n ad hoc basis, tot 'n uitgebrcldc nctwerk. van meetpunte vcrsprei oor die hele land, Standaard mcetstruktuure aangepas vir plaaslike omstandighede is ontwikkei en sluit in doelgeboudc saamgestelde mcetstrukture. Byltans aile saamgestelde mcetstruklure in Suid-Afrika is weens praktisc oorwegings opgerig sonder verdeelmure, wal afwyk van die standaarde gestel deur die British Standards Institution (1981). Onsekerhede aangaande die akkuraathcid ,'an die kaJibrasie van sulke slrukture moes opgekJaar word en unpassjngs un die beSlaande leorie moes gedoen word om hier'OOf te kompenseer. iodien nodig. Oil was ook nodig om va~ Ie s,tel of akkuraathede Waf hulbaar is voldoende is, met inagneming Vlll poIensi~1c finamiitle implikasies van onakkuruthede. Oit hel dus nodig gcword om die bestaandc kaJibra.liic van saamgestelde meetstrukture. hoofsaakJik Crump en sterpkroin meetwaJle, Ie hcr·cval~r. Seleere vloei:rekords is ontl~ en die data is gcbruik om die impak van foule ~ bepaal op die berekende k.apasitei~ van opgaardamme. Oil IS gedoen in 'n poging om riglyne neer te Ie rakende die akkuraatheid verlang in 'n vloeirekord. Die ontleding van '0 enkele loepassing van 'n vloeirekord lewer nie genoegsame data om riglyne vas Ie stell. "ir die verlanp akkuraalheid van 'n vloeirekord of vloeimeling nie. AlhoeweJ geen duidelike riglyne hieruii vOilr1spruit nie. kom dit voor asof die voordele verkry uit '0 verbetering io die akkuraatheid van 'n vloeirekord in verhouding groter is as die vcrmiodering in die vloeimetingsfout. Drie-dimensionele II'loeitoeslande bestaan of stroomop of stroomaf van die punt van watervlakmeting, afl1iangende van die 'cenwoordigheid of afwesigheid van vcrdeelmure by 'n saamgestclde meetstlruktuur. Die beslaande kalibrasieleorie maak nie voorsiening vIr die invloed van drie-dimensionele vloeitoestande en die gepaardgaande energieverlicse op die bepahng van die totale stroomop energiehoogte nie. Hidrouliese mode1tor: sc is ondemeem om die omvang van die resulterende energieverliese vas te ste!. Nuwe tegnieke in die kaJibrasieteorie vir saamgestelde strukture is ontwikk.e1 0:t1 tc kompenseer vir hierdie energieverliese. 'n Verbc:tcde akkuraatheid word verkry wanneer die nuwe tegniek toegepas word op die kalibrasie van saamge~telde meetstrukture met 'n enkele punt van watervla.kmeting. Daar is gevind daR saamgestelde meetstrukture sonder verdeelmure illurater gekalibn:er lean word. as suuktt.Rmet vcrdeelmure waar walervlakke slegs by 'n enkclc punt gemeet word.

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.<br>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.

Thesis (MEng)--University of Stellenbosch, 2000.<br>ENGLISH ABSTRACT: The compound sharp-crested weir, which consists of two or more notches at different elevations, is the most common type of flow gauging structure found in South Africa. The Department of Water Affairs and Forestry (DWAF) is responsible for the operation of these weirs. They are currently experiencing the following problems regarding flow measurement with compound sharp-crested weirs: 1. During free-flow conditions, also known as modular flows, there is uncertainty about the accuracy of the discharge formulas. Although reliable formulas exist for single notch weirs, it is not clear how they should be modified for compound weirs. Whilst methods have already been developed to deal with compound weirs their accuracy needs to be investigated further. 2. When the weirs become submerged during floods, the upstream water head is affected by downstream water levels and the original formulas are not applicable. It has so far been impossible to calculate discharge accurately under these so-called non-modular flow conditions. This report summarises the findings of an extensive study which addressed the issues mentioned above. A comprehensive test programme was completed during which variations of compound sharp-crested weirs were tested under both modular and non-modular flow conditions. In the development of new methods care was taken to adhere to internationally accepted standards. This should make South African practice acceptable to others. One important characteristic of compound weirs is the presence of end contractions. It was found that they have a significant effect on discharge measurement. Generally, the more a weir is contracted, the lower its coefficient of discharge becomes. It was also established that end contractions can ensure excellent aeration for compound weirs. For modular flow conditions it was possible to develop a discharge formula based on the IMFf equation, which is included in the ISO standards. This new method was found to produce the smallest errors when compared to other existing formulas (average error 0.6%). During non-modular flow conditions it was noted that end contractions also play an important role, at least during the early stages of submergence. In full-width weirs the upstream water level tends to drop first (due to de-aeration) before it rises again with increasing submergence. Weirs with end contractions do not suffer from this problem. It was further established that the effect of submergence could be described in terms of an energy loss occurring at the drowned weir. This energy loss is a function of the velocities at the so-called vena contracta of the weir and at the downstream river cross section. As the difference between these velocities increases, the energy loss increases as well. Two methods were tested to estimate the discharge under submerged conditions. The Villemonte formula works well if the energy losses at the weir are relatively high, while the Wessels method is reliable if the energy losses become smaller. A procedure was developed which indicates when each method is applicable. The test data indicated that the maximum error is up to ±10% at high submergence ratios (S> 0.80) if this procedure is followed.<br>AFRIKAANSE OPSOMMING: Multikeep-skerpkruinmeetstrukture bestaande uit twee of meer kepe op verskillende vlakke word meestal gebruik om vloeie in Suid-Afrikaanse riviere te meet. Die Departement van Waterwese en Bosbou (DWAF) is verantwoordelik vir die instandhouding van sulke meetstrukture. Hulle ervaar tans die volgende probleme met vloeimeting by multikeepskerpkruine: 1. Gedurende modulêre (onversuipte) toestande bestaan daar nog onsekerheid oor die akkuraatheid van die formules wat gebruik word om vloeitempo's te bereken. Alhoewel betroubare formules ontwikkel is vir enkelkepe, is dit nie duidelik hoe hulle aangepas kan word sodat hulle ook vir multikepe gebruik kan word nie. Die akkuraatheid van sommige bestaande metodes vir multikepe moet ook ondersoek word. 2. Onder versuipte toestande word die stroom-op watervlak beïnvloed deur die stroom-af watervlak en die formules vir vry-vloei toestande is nie geldig nie. Dit was tot nou toe nie moontlik om vloeitempo ' s akkuraat te bereken onder hierdie nie-modulêre toestande nie. Hierdie verslag bied 'n opsomming van die bevindinge van 'n navorsingsprojek wat bogenoemde probleme aangespreek het. 'n Toetsprogram is uitgevoer wat moontlike konfigurasies van multikepe ingesluit het. Die modelle van die meetstrukture is onder beide vry-vloei en versuipte toestande bestudeer. Gedurende die ontwikkeling van nuwe formules vir die berekening van vloeie is daarna gestreef om so veel as moontlik gebruik te maak van internasionale standaarde. Dit behoort Suid-Afrikaanse praktyke vir andere aanvaarbaar te maak. 'n Belangrike eienskap van multikepe is die voorkoms van end-kontraksies. Hulle het 'n groot invloed op vloeimeting en oor die algemeen het 'n keep met groot end-kontraksies 'n laer vloei koëffisient as 'n vol-wydte keep. End-kontraksies is ook baie effektief om skerpkruine te belug. Vir vry-vloei toestande is gevind dat 'n metode gebaseer op die IMFT vergelyking (ingesluit in ISO standaarde) baie goeie resultate lewer. In vergelyking met ander bestaande metodes gee dié metode die kleinste foute met 'n gemiddelde fout van 0.6%. Onder versuipte toestande speel end-kontraksies ook 'n belangrike rol, ten minste by beperkte versuiping. As vol-wydte kepe beskou word, kan gesien word dat die stroom-op watervlak eers daal voordat dit weer styg (weens ontlugting). Kepe met end-kontraksies ly nie aan hierdie probleem nie. Dit is verder bevestig dat versuipte toestande beskryf kan word in terme van 'n energie verlies wat by die versuipte meetstruktuur voorkom. Hierdie energie verlies is 'n funksie van die snelhede by die vena contraeta van die keep en by die stroom-af rivier snit. As die verskil tussen die twee snelhede groot is, is die energie velies ook groot. Twee bestaande metodes vir versuipte toestande is getoets. Villemonte se vergelyking werk goed as die energie verliese groot is, terwyl Wessels se metode beter werk as die verliese klein raak. 'n Prosedure is ontwikkel wat dit moontlik maak om die regte metode te kies vir 'n spesifieke toestand. Vanaf die toetsdata is bepaal dat die maksimum fout ±10% is by hoë grade van versuiping (S> 0.80) wanneer bogenoemde prosedure gevolg word.

Thesis (MEng)--University of Stellenbosch, 2000.<br>ENGLISH ABSTRACT: As part of a previous WRC project, three types of sluicing flumes were developed for use in compound weirs in combination with sharp-crested and crump weirs, (Rossouw et al., 1998). These sluicing flumes have several advantages which make them ideal structures for flow measurement in South African rivers. These are a high modular limit, stable modular flow characteristics, an ability to measure a wide range of flows accurately, as well as good sediment handling characteristics. These three flumes have been calibrated under modular or free flow conditions in combination with sharpcrested and crump weirs. There is a high degree of variability of flow in South African rivers. Flood discharges are part of this variability, and can form an important part of the mean annual runoff. Measuring weirs cannot always be built so that they do not become submerged during floods, but it is nevertheless important that flood discharges be recorded. It is therefore important that these compound weirs be calibrated for flow measurement under non-modular or submerged conditions. The purpose of the research undertaken for this WRC project is to find a method to calculate the non-modular discharge over compound weirs consisting of sluicing flumes in combination with sharp-crested and crump weirs. By analysis of existing data from the previous WRC project, as well as data from laboratory tests undertaken as part of this project, the submergence effect of sluicing flumes has been quantified. A range of configurations of sharp-crested weirs as well as crump weirs in combination with the sluicing flume have been tested. A new method has been developed to calculate the submerged discharge over these compound weirs. This method is suitably accurate, and can be recommended to the DWAF for use. The calculation procedure that must be followed in order to calculate the submerged discharge over these compound weirs becomes rather complicated due to the iterations that must be carried out. In order to clarify these procedures, flow charts are provided which set out the steps that must be followed. Calibration curves for all the combinations of compound weirs analysed in this report are also provided. These can be used to obtain estimates of the discharge in the field, and can also be used as a check on any calculations carried out. The principal goal of this project, namely that of finding a suitably accurate method to calculate the non-modular discharge over these compound weirs has therefore been achieved.<br>AFRIKAANSE OPSOMMING: As deel van 'n vorige Water Navorsings Kommisie (WNK) projek, is drie spoelgeute ontwikkel vir gebruik in saamgestelde meetwalle in kombinasie met skerp-kruin en Crump oorlope, (Rossouwet al., 1998). Die spoelgeute het eienskappe wat hulle gunstig maak vir vloeimeting in Suid Afrikaanse riviere. Vanhierdie eienskappe is 'n hoë modulêre limiet, stabiele modulêre vloei eienskappe, goeie sediment hanterings eienskappe en 'n vermoë om oor 'n wye bereik vloeie akkuraat te kan meet. Hierdie drie geute is in kombinasie met skerpkruin en Crump oorlope gekalibreer onder vryvloei toestande. Vloeie varieër baie in Suid Afrikaanse riviere. Vloede is deel van hierdie variasies en maak 'n belangrike deel uit van die gemiddelde jaarlikse afloop. Meetwalle kan nie altyd gebou word sodat hulle nie versuip tydens vloede nie, maar dit is nogtans belangrik dat hierdie vloeie gemeet word. Daarom is dit belangrik dat saamgestelde meetwalle gekalibreer is vir vloeimeting onder versuipte of nie-modulêre toestande. Die doel van die navorsing wat gedoen is vir hierde WNK projek was om 'n geskikte metode te ontwikkel om die nie-modulêre vloeie oor saamgestelde meetwalle, wat bestaan uit spoelgeute in kombinasie met skerpkruin en Crump oorlope, te kan bereken. Met die analise van bestaande data van die vorige WNK projek, asook data van labratoriumtoetse wat gedoen is as deel van hierdie projek, is die versuiping van spoelgeute beskryf. 'n Hele reeks skerpkruin asook crump oorlope is getoets in kombinasie met die spoelgeute. 'n Nuwe metode is ontwikkel om die nie-modulêre vloei oor hierdie saamgestelde meetstrukture te kan bereken. Hierdie metode IS akkuraat genoeg om aan die Departement van Waterwese te kan aanbeveel. Die berekingsproses wat gevolg moet word om die versuipte vloei oor die saamgestelde meetstrukture te bereken, raak ingewikkeld as gevolg van die iterasies wat uitgevoer moet word. Vloeidiagramme is opgestel wat hierdie prosedures duidelik uiteensit. Kalibrasie kurwes is ook ontwikkel vir al die kombinasies van saamgestelde meetwalle wat geanaliseer is in hierdie verslag. Hierdie kurwes kan gebruik word om skattings te maak van vloeie in die veld, maar ook om enige berekings wat gedoen is te kontroleer. Die hoofdoel van hierdie projek, naamlik om 'n geskikte metode te ontwikkel wat die nie-modulêre vloeie oor saamgestelde meetwalle akuraat kan bereken, is bereik.

The Utah Water Research Laboratory, in conjunction with the State of Utah, initiated a study to determine the accuracy of a wide variety of flow measurement devices in Utah. The project selected 70 sites with flow measurement devices throughout the state. During the assessment each device had its physical condition and flow measurement accuracy documented. Although a wide variety of flow measurement devices were tested, the majority were Parshall flumes. Many of the assessed Parshall flumes were not measuring flow to the specified ±5 percent design accuracy. Problems in flow measurement were due to issues with the staff gauge location and incorrect entrance geometry. Laboratory tests were conducted at the Utah Water Research Laboratory in an attempt to provide accurate flow measurement from flumes with these issues. The tests simulated incorrect locations for measuring upstream head with different entrance geometries on a 2-ft-wide Parshall flume. The flume was tested with three different entrance wingwall configurations, eighteen stilling wells, and two point gauges, allowing water surface profiles to be collected throughout the flume. Corrections for incorrect head measurement locations and entrance geometries were created. The objective of this thesis is to provide water users and regulators with the information necessary to help improve open-channel flow measurement accuracies. An overview of design accuracies and flow measurement devices is given. In addition, a method to correct for incorrect head readings in Parshall flumes, a widely used flow measurement device in Utah, is presented. It is expected that this information will help water users and regulators monitor their water with the understanding necessary to ensure that water is more accurately measured.

<p>The rehabilitation of dams often requires spillway capacity upgrades. Replacing a less hydraulically efficient linear weir with a labyrinth weir can be an effective way to increase discharge efficiency (discharge at a given upstream head) for a fixed-width channel. Labyrinth weirs are linear weirs folded in plan view to increase total spillway crest length (which in turn increases discharge efficiency within a channel). Labyrinth weirs potentially have limitless geometric configurations. This study was performed to analyze the effects of varying certain geometric parameters on discharge efficiency and design method predictions. Due to limited cross-sectional flow area near the upstream apex, labyrinth weirs experience nappe collision and local submergence that potentially reduce discharge efficiency. The increase of upstream apex width may be a feasible method to decrease the negative effects of nappe interference, which in turn may increase discharge efficiency.This was analyzed in this study by testing a series of eight laboratory scaled labyrinth weirs (with sidewall angles of 12?), with various upstream apex widths. Upstream apex width tests were performed in a fixed and varied channel width setting. The design method developed by Crookston and Tullis is based on laboratory scaled physical models. This method is very useful in the estimation of performance for geometrically similar prototype labyrinth weirs. However, due to difficulty in obtaining data on completed prototype weirs, design method predictions are rarely verified. To help validate Froude scaling and design method predictions of prototype weirs, a series of physical model tests (with sidewall angles of 15?) were performed with varying scale sizes (0.5 to 3.0 compared to the size of weir used in the design method). To expand the applicability of the design method to common geometric variations, tests were performed on weirs of varying weir height and cycle width (with sidewall angles of 15?). These variations were applied independently and analyzed to determine their effects on discharge efficiency and design method predictions. A correction factor is then presented to be used in conjunction with Crookston and Tullis's design method for these geometric variations. All conclusions are presented in this thesis.

The variability of the South African (SA) climate results in abrupt changes in river discharge rates. Compound weirs have been implemented as an attempt to ensure accurate discharge calculations over an extended, but limited, range of flows. It would be financially and practically impossible to design compound weirs that can measure the entire range of flow rates that are experienced in SA rivers to the same degree of accuracy. Extensive research on the accuracy of weirs, within their intended hydraulic capacity, has been done over the years. However, when weirs operate above this capacity, three-dimensional flow is observed as a result of the presence of the divider and flank walls. The observed three-dimensional flow causes uncertainty in the application of the current discharge-head relationships, as these relationships were developed with the assumption of parallel flow lines. In this dissertation, a physical model study was done at the Department of Water and Sanitation hydraulic laboratories. The results indicated that the flow rates, calculated using the current discharge-head relationships, consistently over-estimates the input flow rates. Additionally, a numerical model study using Computational Fluid Dynamics (CFD) software STAR-CCM+ was done. CFD proved to be a valuable tool for extending the domain of the study. A comparison of the physical model and numerical model results is shown with some comments on shortcomings identified in the user-defined volume mesh inputs that could not be addressed in this study due to time and resource limitations.<br>Dissertation (MEng)--University of Pretoria, 2020.<br>Water Resources Engineering<br>MEng<br>Unrestricted

The rehabilitation of dams often requires spillway capacity upgrades. Replacing a less hydraulically efficient linear weir with a labyrinth weir can be an effective way to increase discharge efficiency (discharge at a given upstream head) for a fixed-width channel. Labyrinth weirs are linear weirs folded in plan view to increase total spillway crest length (which in turn increases discharge efficiency within a channel). Labyrinth weirs potentially have limitless geometric configurations. This study was performed to analyze the effects of varying certain geometric parameters on discharge efficiency and design method predictions. Due to limited cross-sectional flow area near the upstream apex, labyrinth weirs experience nappe collision and local submergence that potentially reduce discharge efficiency. The increase of upstream apex width may be a feasible method to decrease the negative effects of nappe interference, which in turn may increase discharge efficiency. This was analyzed in this study by testing a series of eight laboratory scaled labyrinth weirs (with sidewall angles of 12°), with various upstream apex widths. Upstream apex width tests were performed in a fixed and varied channel width setting. The design method developed by Crookston and Tullis is based on laboratory scaled physical models. This method is very useful in the estimation of performance for geometrically similar prototype labyrinth weirs. However, due to difficulty in obtaining data on completed prototype weirs, design method predictions are rarely verified. To help validate Froude scaling and design method predictions of prototype weirs, a series of physical model tests (with sidewall angles of 15°) were performed with varying scale sizes (0.5 to 3.0 compared to the size of weir used in the design method). To expand the applicability of the design method to common geometric variations, tests were performed on weirs of varying weir height and cycle width (with sidewall angles of 15°). These variations were applied independently and analyzed to determine their effects on discharge efficiency and design method predictions. A correction factor is then presented to be used in conjunction with Crookston and Tullis’s design method for these geometric variations. All conclusions are presented in this thesis.

Reservoir releases for power generation often cause rapidly fluctuating water levels and increased velocities in certain downstream sections of rivers. These conditions and the natural geometry of the river can render certain sections of the river dangerous for recreation. Although public utilities take precautionary safety measures immediately downstream of the dam, their measures further downstream have been limited, if not non-existent. The placement of weirs between the dam and dangerous sections would retard the flow—slowing the rise in water levels and decreasing velocities at predetermined dangerous sections. Big Falls, on the New River near McCoy, Virginia, is a popular recreation spot and becomes dangerous at certain times of the day due to releases from Claytor Lake Dam. Several people have drowned at this location over the years. In this study, the influence of weirs placed upstream of Big Falls on the rise of water level and increase in velocity is investigated by an implicit finite difference computer model of one-dimensional gradually varied unsteady flow. The model allows for investigation of different weir geometries and placements, and the effectiveness of these weirs when subjected to various boundary conditions which arise from variations of the maximum peak release hydrograph from Claytor Lake Dam from May to September of 1983 and 1984. Results of the study consist of the optimum weir geometry and placement on the New River upstream of Big Falls. Criteria for determining the weir included physical location limitations, and the effectiveness of the weir in reducing the rate-of-rise of water levels and increased velocities at Big Falls.<br>M.S.

This thesis describes the current state of the river Oslava in Oslavany design and reconstruction of the existing fixed weir in the affected location. As a best alternative reconstruction of the existing fixed weir reconstruction was chosen the hard threshold floating weir inflatable weirs. The next part of the thesis describes the proposed solution, and the last part of the thesis deals with the assessment of the proposed solutions.

Linear weirs are a common hydraulic structure that have been used for centuries with many different applications. One characteristic of weirs that is particularly useful is the head-discharge relationship where the discharge over the weir is directly related to the upstream water depth above the crest. In general, the head-discharge relationship for a weir is determined experimentally in laboratories using geometrically similar models. Due to space, time, money, and discharge capacity limitations at water laboratories, creating full scale models is not always a feasible option when determining head-discharge relationships for large prototype weirs. It is typically more cost effective to create a scale model than to build a full scale model or conduct tests on the prototype. Because of this fact, physical modeling has been one the most important tools in determining head-discharge relationships for weirs. However, as the physical size of the model decreases, size scale effects associated with surface tension and viscosity forces can significantly affect the results from the physical model and cause the results to differ from what would actually occur at the prototype scale. Therefore, it is important to understand what affects surface tension and viscosity forces have on the head-discharge relationship for different size weirs and when those effects are no longer negligible. The purpose of this research was to evaluate size scale effects for linear weirs. Weirs models of three different crest shapes (flat-top, quarter-round, and half-round) were constructed and tested at four different geometrically similar sizes [weir heights (P) = 24-, 12-, 6-, and 3-in]. This was done in order to evaluate how size scale effects affect the head-discharge relationship as model size decreases for different crest shapes. Discharge coefficients were calculated for relative upstream head values ranging from 0.01 ≤ Ht/P ≤ 2.0 for vented and non-vented conditions. Nappe aeration behavior was documented and compared to determine where differences in the nappe trajectory occurred as a result of scale effects. Comparisons were made with data from others researchers to determine if the recommendations for minimum head limits were similar to the results from this study. This study examined the errors in the discharge coefficient associated with size scale effects and suggested limits to avoidance depending on model scale and crest shape.

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)<br>Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)<br>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...<br>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<br>Coorientador: Maria Stela Maioli Castilho Noll<br>Banca: Lourdes Maria Abdu El-Moor Loureiro<br>Banca: Eliana Aparecida Panarelli<br>Banca: Maria José dos Santos Wisniewski<br>Banca: Paulina Maria Maia Barbosa<br>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)<br>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)<br>Doutor

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.

Thesis (MEng)--University of Stellenbosch, 2001.<br>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.<br>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.

Nesta dissertação, procedeu-se à avaliação do funcionamento de uma passagem para enguias (PPEnguias), instalada no Açude-Ponte de Coimbra, no rio Mondego, visando facilitar a passagem de juvenis desta espécie para montante. As amostragens realizadas permitiram verificar que a época de migração das enguias com um comprimento inferior a 200mm atinge o pico na primavera e no verão; o troço a jusante do Açude-Ponte é caracterizado por maior número de indivíduos e de menor tamanho, e os troços a montante por menos animais e de maior comprimento. Esta diferença reforça o impacto do obstáculo na migração da espécie e confirma a falta de eficiência da passagem para peixes multiespecífica presente no açude para a população de enguia-europeia. A PPEnguias mostrou-se bem posicionada e estruturada, permitindo às enguias encontrar a entrada e completar o trajeto. É necessário continuar os estudos de forma a averiguar a eficácia da passagem e o seu impacto a longo prazo; Evaluation of the operation of the eel pass installed in the Açude-Ponte dam at Coimbra Abstract: In this dissertation, the operation of an eel passage (PPEnguias), installed in the Açude-Ponte dam at Coimbra, on the Mondego River, to facilitate the passage of this species’ juveniles upstream, was evaluated. Sampling made it possible to determine that eel’s under 200mm migration period reaches its peak in spring and summer; downstream of the Açude-Ponte presents larger number of individuals and smaller sizes, and upstream less animals and longer lengths. This difference reinforces the impact of the obstacle on the species’ migration and confirms the lack of efficiency of the fish passage present at the weir for the European eel population. PPEnguias was well positioned and structured, allowing the eels to find the entrance and complete the course. It is necessary to continue studies to ascertain the effectiveness of the passage and its long-term impact.

nÃo hÃ<br>O barramento do fluxo natural do rio Jaguaribe, com a construÃÃo da barragem do CastanhÃo, no limite entre o mÃdio e baixo curso, inserido na polÃtica de gestÃo das Ãguas do Estado do CearÃ, alterou consideravelmente a vazÃo, que no inÃcio do sÃculo XX era de 200 m/s, para menos de 40 m/s nos dias atuais. No entanto, as modificaÃÃes nÃo sÃo apenas da Ãgua barrada, mas na interrupÃÃo do fluxo de sedimentos, acarretando alteraÃÃes no ciclo hidrosedimentolÃgico e nas feiÃÃes geomorfolÃgicas. Associados ao processo de aÃudagem estÃo os impactos das alteraÃÃes e mudanÃas no quadro ambiental considerÃvel em apenas uma dÃcada. O processo de acumulo de sedimento na bacia hidrÃulica do CastanhÃo, as Ãreas ocupadas por ilhas fluviais no leito natural e a jusante do barramento variaram de maneira considerÃvel; assim como na planÃcie litorÃnea e na Ãrea do entorno da foz. As ferramentas de geoprocessamento e as tÃcnicas de Sensoriamento Remoto aplicadas na tese levaram a definiÃÃo de trÃs unidades diferentes: bacia hidrÃulica, baixo curso/planÃcie fluvial e foz/linha de costa adjacente. Esta tendÃncia de modificaÃÃo ambiental, onde o aporte de sedimento no prÃprio aÃude foi inferido, a modificaÃÃo do leito à jusante identificado, e a erosÃo e acumulaÃÃes nas margens da foz e linha de zona costeira adjacente foram detectadas atravÃs das modelagens hidrolÃgicas.<br>The bus of the natural flow from Jaguaribe river, with the construction of the CastanhÃo dam, on the edge between the middle and lower courses of it that are inserted in the policy of the waterâs management of Cearà State changed considerably the flow, which in the early 20th century was 200m/s, for less than 40m/s nowadays. However, the changes are not only from barred water, but on the interruption of the flow of sediments, causing changes in the hidrosedimentolÃgico cycle and the geomorphological features. Associated with the damming process are the impacts of changes and the changes in considerable environmental framework in just a decade. The process of accumulation of sediment in the hydraulic basin of CastanhÃo, the areas occupied by River Islands in the riverbed and downstream of bus ranged from substantial way; as well as in the coastal plain and in the area surrounding the mouth. The tools of the geoprocessing and the Remote Sensing techniques applied in the thesis led to the definition of three different units: hydraulic basin, lower course/river plain and estuary/adjoining coast line. This trend of environmental modification, where the amount of sediment in the pond itself is implied, the modification of downstream riverbed identified, and erosion and accumulations on the banks of the estuary and adjacent coastal zone line were detected through the hydrological modeling.

The irrigated farm crops are the main users of water. With this, in places where there is a water shortage to attend all sorts of use, this kind of activity is characterized like as a potentially conflicting, once that to produce one hectare of rice, are necessary thousands cubic meters of water. To work out this conflict, many actions are been developed, as giving rights and tax to use water. Although, to the effectiveness of that actions, is necessary an effective inspection over all of the producers and users, monitoring each volume used. Being a inspection this kind unsustainable to the manager, is necessary the study of methodologies to determine water flow and volumes of irrigation, which shall be easily understood and applied, to be used by the producers themselves. Were tested, comparatively, two sorts of hydraulics systems, sharp crested Weirs and Velocimetric Hydrometers, measurers of water flow and volumes respectively, for monitoring the volumes of irrigation of two parcels of irrigated rice in the harvest 2009/2010, located in Cachoeira do Sul city, in Capané locality. In each parcel, one with Direct tillage and area of 0,66 ha and another one with Conventional tillage and area of 0,80 ha, the monitoring of water occurred simultaneously by using the Weirs and Hydrometers installed in sequence and confined, in other words, the monitored water was the same in both systems. Was used Pluviometer to monitoring the total volume of rain fall, in order that, with the irrigation volume was calculated the total volume necessary to that rice parcels. The results of the comparative monitoring between Weirs of Thin Wall and Velocimetric Hydrometers showed a small difference in the final results, been the difference of 1,15% bigger by the Hydrometer in relation to Weir in the parcel with Direct tillage and 6,75% smaller by Hydrometer in relation to Weir in Conventional tillage. However, Were verified daily variations between the Weirs and Hydrometers that reached 82% in the Direct tillage and 39% in the Conventional tillage. The total volume monitored to each parcel was 8565,15 m³/ha in the parcel with Direct tillage and 9987,25 m³/ha in the conventional tillage, both considering the results of Weirs. With the results found and the characteristics of operation and maintenance of the analyzed systems, is checked the availability of using sharp crested Weirs for monitoring water quantity in rice crops, although by the comparatively study oh both systems, is not recommended to use hydrometers in these ways.<br>As lavouras de arroz irrigado são as principais usuárias de água durante o seu ciclo produtivo. Com isto, em locais onde existe escassez de água para atender a diversos usos este tipo de empreendimento se caracteriza como um potencial conflitante, uma vez que para produção de um hectare de arroz são necessários milhares de metros cúbicos de água. Para resolver estes conflitos, muitos instrumentos estão sendo desenvolvidos, como a outorga e a cobrança pelo uso da água. No entanto, para a efetividade destes instrumentos, é necessária uma fiscalização extensiva sobre todos os produtores e usuários, monitorando os respectivos volumes utilizados. Sendo uma fiscalização deste tipo insustentável para o órgão gestor se faz necessário o estudo de metodologias de determinação de vazões e volumes de irrigação que sejam de fácil entendimento e aplicação, para que possam ser utilizadas e monitoradas pelos próprios produtores rurais (automonitoramento). Foram testados comparativamente dois tipos de sistemas hidráulicos, Vertedores de parede delgada e Hidrômetros Velocimétricos, medidores de vazões e volumes respectivamente, para monitoramento dos volumes de irrigação de duas parcelas de arroz irrigado na safra de 2009/2010, localizados na cidade de Cachoeira do Sul, na localidade de Capané. Em cada uma das parcelas, uma com sistema de plantio Direto e área de 0,66 ha e outra com plantio Convencional com área de 0,80 ha, o monitoramento da água ocorreu de forma simultânea através da utilização de vertedores e hidrômetros instalados em série e confinados, ou seja, a água monitorada por um era a mesma que a monitorada pelo outro. Foi utilizado Pluviômetro no monitoramento do volume total de precipitações, para que juntamente com o volume de irrigação fosse determinado o volume total necessário ao cultivo do arroz naquelas parcelas. O resultado do monitoramento comparativo entre Vertedores e Hidrômetros apresentou pequena variação no resultado final, sendo a diferença de 1,15% monitorada a mais pelo Hidrômetro em relação ao vertedor na parcela com plantio Direto e 6,75% a menos pelo Hidrômetro que o Vertedor na parcela com plantio Convencional. No entanto, foram verificadas variações diárias entre os Vertedores e os Hidrômetros que alcançaram 82% no plantio direto e 39% no plantio convencional. O volume total monitorado para cada parcela foi de 8565,15 m³/ha na parcela com plantio Direto e 9987,25 m³/ha no plantio Convencional, ambos considerando os resultados obtidos com os vertedores. Com os resultados obtidos e as características de operação e manutenção dos sistemas analisados, verifica-se a viabilidade da utilização de Vertedores de parede delgada para o automonitoramento de água em lavouras orizicolas, no entanto, através do estudo comparativo dos dois sistemas, não se recomenda a utilização de Hidrômetros Velocimétricos neste meio.

The Staunton River is a high gradient, second order stream approximately 6 km in length located on the eastern slope of the Blue Ridge Mountains in Shenandoah National Park, VA. In June 1995, a catastrophic flood and debris flow altered the instream habitat and <i>Salvelinus fontinalis</i> population of the Staunton River. The debris flow scoured the streambed, deposited new substrate materials, removed trees from the riparian zone, and eliminated fish from a 1.9km section of the stream. By June 1998, both young-of-year (YOY) and age 1+ <i>S. fontinalis</i> had recolonized the debris flow affected area. The event provided a rare opportunity to examine recovery of the <i>S. fontinalis</i> population and instream habitat in addition to addressing potential effects of the debris flow on movement, activity, and growth of fish in the debris flow affected and unaffected areas of the stream. Post-recolonization movement and activity were monitored using two-way fish traps (weirs), mark-recapture techniques, and radio telemetry. The weirs failed to produce any movement data. Most fish (91%) in the mark-recapture study had range sizes less than 100m, however biases common to mark-recapture study designs (low recapture rate, flawed logic, etc.) hampered interpretation of results. For example, subsequent recapture of individually marked fish indicated that as many as 54% of marked fish confirmed to have been alive at the time of a recapture session were not recaptured. Radio telemetry provided information on <i>S. fontinalis</i> movement and activity at seasonal and diel scales during summer and fall. Differences in movement and activity between the debris flow affected and unaffected areas were minimal when compared to seasonal variations. During summer, range sizes were near 0m and crepuscular activity patterns were observed. During the fall range size increased and diel activity was concentrated in the mid-afternoon with a much higher peak than during summer. Basin-wide visual estimation technique (BVET) fish population surveys performed each spring and fall from 1993 = 1999 provided pre- and post-event fish population abundance and density estimates. Post-event fish growth in the debris flow affected and unaffected areas was monitored using mark-recapture techniques. Abundance and density of both YOY and age 1+ <i>S. fontinalis</i> exceeded pre-event levels within 2-3 years. Growth of YOY and age 1+ fish was significantly greater in the debris flow affected area until spring 1999. Population density appeared to have a strong negative influence on growth. The observed changes in fish growth and differences in fish size associated with population density would be of minimal importance to the typical angler but may suggest a mechanism by which <i>S. fontinalis</i> populations can quickly recover from catastrophic events. BVET habitat surveys provided information on total stream area, number of pools and riffles, pool and riffle surface area and depth, substrate composition, and large woody debris (LWD) before (1993), immediately following (1995), and four years post-event (1999). Immediately following the debris flow, the stream channel was highly disordered which resulted in an increase in the total number of habitat units and a decrease in average habitat unit surface area, total stream area, and average depth when compared with pre-event conditions. In addition, substrate composition had shifted from small to large diameter particles and LWD loading had increased in both debris flow affected and unaffected areas. Four years after the event, the total number of habitat units, average habitat unit surface area, total stream area, and average depth had all returned to near pre-debris flow levels and substrate composition had begun to shift towards smaller particle sizes. Changes in LWD loading from 1995-1999 reflected changes in the riparian zone following the debris flow. In the unaffected area, where riparian trees remained intact, LWD loading increased, whereas in the debris flow affected area, where riparian trees were eliminated, LWD loading decreased. For the most part the effects of the debris flow, although immediately dramatic, were in the long term minimal. The debris flow affected area was recolonized rapidly and abundance and density quickly rebounded past pre-event levels. Differences in fish growth between the affected and unaffected area were short lived. Any effect the debris flow affected area may have had on movement or activity was minimal when compared with seasonal variations. Most habitat characteristics reverted to near pre-event levels just four years after the flood and debris flow. Although a number of factors will influence recovery time from such events, these results indicate that immediate management action, such as stocking or habitat modifications, are not necessary in all cases.<br>Master of Science

Weird fiction is a mode in the Gothic lineage, cognate with horror, particularly associated with the early twentieth-century pulp writing of H.P. Lovecraft and others for Weird Tales magazine. However, the roots of the weird lie earlier and late-Victorian British and Edwardian writers such as Arthur Machen, Count Stenbock, M.P. Shiel, and John Buchan created varyingly influential iterations of the mode. This thesis is predicated on an argument that Lovecraft’s recent rehabilitation into the western canon, together with his ongoing and arguably ever-increasing impact on popular culture, demands an examination of the earlier weird fiction that fed into and resulted in Lovecraft’s work. Although there is a focus on the literary fields of the fin de siècle and early twentieth century, by tracking the mutable reputations and critical regard of these early exponents of weird fiction, this thesis engages with broader contextual questions of cultural value and distinction; of notions of elitism and popularity, tensions between genre and literary fiction, and the high/low cultural divide allegedly precipitated by Modernism.