Dissertationen zum Thema „River discharges“
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Cloete, Gert Christiaan. „River discharges derived from single velocity measurements“. Thesis, Stellenbosch : Stellenbosch University, 2004. http://hdl.handle.net/10019.1/50087.
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Thesis (MScEng)--University of Stellenbosch, 2004.ENGLISH ABSTRACT: This work investigates methods to theoretically determine the lateral velocity distribution across a river from which factors may be derived to translate a single point velocity into average velocity for the river as a whole. A wide range of field data from vanous nvers was analysed. This produced over a hundred velocity distributions with which to compare theoretical distribution results. Four theoretical approaches were considered: the one-dimensional method (Manning's equation), a two-dimensional flow formula solved as an initial-value-problem, a two dimensional flow formula solved as a boundary-value-problem and an empirical method developed from energy principles. The one-dimensional and initial-value-problem approaches were unsuccessful. The boundary-value and empirical approach did however produce promising results. Surprisingly the analysis of the field data revealed patterns of similarity which could produce accurate results without the need of a theoretical approach.
AFRIKAANSE OPSOMMING: Metodes word ondersoek om teoreties 'n laterale snelheidsverspreiding oor 'n rivier te bepaal en sodoende 'n faktor te vind waarmee 'n gemete enkelpuntsnelheid in die rivier omgeskakel kan word na 'n gemiddelde snelheid vir die rivier in geheel. Vloeimeetdata van verskeie nviere IS geanaliseer. Sodoende is meer as 100 snelheidsverspreidings gegenereer waarmee die teorie vergelyk kon word. Vier teoretiese benaderings is gevolg: Manning se een-dimensionele vloeivergelyking, 'n twee dimensionele vloei-vergelyking opgelos met behulp van 'n beginwaarde, 'n twee dimensionele vloei-vergelyking opgelos met behulp van randwaardes, en 'n empiriese metode ontwikkel vanuit energie beginsels. Die een-dimensionele- en beginwaarde-benaderings was me suksesvol me. Die randwaarde- en empiriese benaderings het wel belowende resultate gelewer. Selfs verwerking van die gemete stroommetings het waardevolle inligting gelewer: daar bestaan duidelike ooreenkomste in die snelheidsverspreidings wat gebruik kan word om die verspreidingsfaktor mee te bereken sonder om teoretiese oplossings te soek.
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Aulinas, Masó Montse. „Management of industrial wastewater discharges in river basins through agents'argumentation“. Doctoral thesis, Universitat de Girona, 2009. http://hdl.handle.net/10803/7804.
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La gestió de l'aigua residual és una tasca complexa. Hi ha moltes substàncies contaminants conegudes però encara moltes per conèixer, i el seu efecte individual o col·lgectiu és difícil de predir. La identificació i avaluació dels impactes ambientals resultants de la interacció entre els sistemes naturals i socials és un assumpte multicriteri. Els gestors ambientals necessiten eines de suport pels seus diagnòstics per tal de solucionar problemes ambientals.Les contribucions d'aquest treball de recerca són dobles: primer, proposar l'ús d'un enfoc basat en la modelització amb agents per tal de conceptualitzar i integrar tots els elements que estan directament o indirectament involucrats en la gestió de l'aigua residual. Segon, proposar un marc basat en l'argumentació amb l'objectiu de permetre als agents raonar efectivament. La tesi conté alguns exemples reals per tal de mostrar com un marc basat amb agents que argumenten pot suportar diferents interessos i diferents perspectives. Conseqüentment, pot ajudar a construir un diàleg més informat i efectiu i per tant descriure millor les interaccions entre els agents. En aquest document es descriu primer el context estudiat, escalant el problema global de la gestió de la conca fluvial a la gestiódel sistema urbà d'aigües residuals, concretament l'escenari dels abocaments industrials. A continuació, s'analitza el sistema mitjançant la descripció d'agents que interaccionen. Finalment, es descriuen alguns prototips capaços de raonar i deliberar, basats en la lògica no monòtona i en un llenguatge declaratiu (answer set programming).
És important remarcar que aquesta tesi enllaça dues disciplines: l'enginyeria ambiental (concretament l'àrea de la gestió de les aigües residuals) i les ciències de la computació (concretament l'àrea de la intel·ligència artificial), contribuint així a la multidisciplinarietat requerida per fer front al problema estudiat. L'enginyeria ambiental ens proporciona el coneixement del domini mentre que les ciències de la computació ens permeten estructurar i especificar aquest coneixement.
Wastewater management is a very complex task. There is a high number of known and an increasing number of unknown pollutants whose individual and collective effects are very difficult to predict. Identifying and evaluating the impacts of environmental problems resulting from the interactions between our social system and its natural environment is a multifaceted critical issue. Environmental managers require tools to support their diagnoses for solving these problems. The contributions of this research work are twofold: first, to propose the use of an agent-based modelling approach in order to conceptualize and integrate all elements that are directly or indirectly involved in wastewater management. Second, to propose a framework based on argumentation that allows to reason effectively. The thesis provide some real examples to show that an agent-based argumentation framework can deal with multiple interests and different agents' perspectives and goals. This help to build a more effective and informed dialog in order to better describe the interaction between agents. In this document we first describe the context under study, scaling down the global river basins system to the urban wastewater systems and giving some more details for the specific scenario of industrial wastewater discharges. Then, we analyze the system in describing intelligent agents that interact. Finally, we propose some reasoning and deliberation prototypes by using an argumentation framework founded on non-monotonic logics (i.e. permitting to learn things that were previously not known) and the answer set programming specification language (i.e. a declarative programming language). It is important to remark that this thesis links two disciplines: environmental engineering (specifically the area of wastewater management) and computer science (specifically the area of artificial intelligence), contributing to the required multidsciplinarity needed to confront the complexity of the problem under study. From environmental engineering we obtain the domain knowledge whereas the computer science field permits us to structure and specify this knowledge.
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Holt, Tom. „The effect of proposed Soviet river diversions on Arctic Sea ice processes“. Thesis, University of East Anglia, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.278089.
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Jian, Jun. „Predictability of Current and Future Multi-River discharges: Ganges, Brahmaputra, Yangtze, Blue Nile, and Murray-Darling Rivers“. Diss., Atlanta, Ga. : Georgia Institute of Technology, 2007. http://hdl.handle.net/1853/19777.
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Thesis (Ph.D)--Earth and Atmospheric Sciences, Georgia Institute of Technology, 2008.Committee Chair: Judith Curry; Committee Chair: Peter J Webster; Committee Member: Marc Stieglitz; Committee Member: Robert Black; Committee Member: Rong Fu.
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Dias, Francisco Josà da Silva. „HidrodinÃmica of discharges to the river estuary of the Rio Jaguaribe (CE.)“. Universidade Federal do CearÃ, 2007. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=1728.
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Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgicoThe increasing of greenhouse gases and of the human population, results in growing awareness of water resources managers of freshwater availability in the world, mostly in the tropics. Knowing that Brazil still presents an excellent availability of freshwater, with 33.000 m3.inhabitant.years, the Ministry of the Environment, in a recent publication, stands out that the Basins of the Eastern Northeast Atlantic, in which the Jaguaribe river is inserted, already presents a high level of estress of their water bodies, with only 45% of the minimum value of the 2.500 m3.inhabitant.years suggested by the Organization of United Nations (ONU) as being the minimum required to the exercise of the human social and economic activities. The water discharge of the Jaguaribe river basin, with 72,043 km2 of area and 633 km2 of extension, measured at the nearest seaward station, indicates historical average outflows varying between 14 Â 23 m3.s-1 in the dry season and up to 235 Â 434 m3.s-1 in the rain season. However, this fluvial discharge can not be considered as discharging to the ocean, because the basins reservoirs holds back 87% of the fluvial flow. The modeling of river flow performed in the present study at tidal river zone (ZR) and the mixture zone (ZM) interface under quadrature tides in February and June 2006, and under spring tide, in September 2005, showed total outflow varying between 58 and 183 m3.s-1 in the evaluated period. The residence time (TR) of estuarine waters was dependent on the inter-annual climatic variability varying from 3 to 2 hours in the dry station, in 2005 and 2006, respectively, and 12 hours at the season, evidencing that the volume of freshwater is not a limiting main factor for the ability of the water mass to breach the operating sea strength in the region, but the total outflow is significant, mainly during the dry station when the estuary is leached by sea waters that increase its renew capacity. Highest salinities was observed in the periods when the estuary presented lower input of fluvial waters, reaching the 36,1. The particulate suspended matter (MPS) varied seasonality between 7 and 89,7 mg/L. The MPS in September of 2005 and June of 2006 was strongly organic, and the MPS observed in February of 2006 was mostly of carbonate origin. The discharges of MPS and metals associated with it to the estuary, presented the highest values in the period of larger fluvial flow, varying between 1,9 104 x ton.year-1 in September of 2005 (12% of freshwater origin) to 2,5 105 x ton.year-1 in the period with 95% of freshwater. The same behavior is observed for the discharges of metals, such as; Fe, which in September of 2005 presented a discharge of 3 x 102 ton.year-1, whereas in the period of larger fluvial flux of 1,2 x 104 ton.year-1, having as an exception the Pb flux, which presented the highest values in the period of marine domain.
O crescente aumento da emissÃo dos gases do efeito estufa (GEE) e da populaÃÃo humana fez com que os gestores dos recursos hÃdricos redobrassem sua atenÃÃo sobre a razÃo demanda/disponibilidade hÃdrica no mundo e, principalmente nos trÃpicos. Mesmo sabendo que o Brasil ainda apresenta um excelente potencial hÃdrico, com 33.000 m3.hab-1.ano-1, o MinistÃrio do Meio Ambiente, em recente publicaÃÃo, ressalta que a bacia do AtlÃntico Nordeste Oriental, no qual o rio Jaguaribe esta inserido, jà apresenta um elevado nÃvel de estresse hÃdrico por apresentar apenas 45% do valor mÃnimo de 2.500 m3/hab/ano apontado pela ONU como sendo suficientes para a manutenÃÃo das atividades humanas, sociais e econÃmicas. A descarga hÃdrica da bacia de drenagem do rio Jaguaribe, (72.043 km2 de Ãrea e 633 km2 de extensÃo) medida pela estaÃÃo fluviomÃtrica mais prÃxima a sua foz, na regiÃo do mÃdio Jaguaribe, indica vazÃes mÃdias histÃricas variando entre 14 +23 m3.s-1 na estaÃÃo de seca atà 235 +434 m3.s-1 na estaÃÃo de chuvas. No entanto, esta descarga fluvial nÃo deve ser considerada como o aporte fluvial da bacia para o oceano, pois a aÃudagem retem 87% do fluxo fluvial do Jaguaribe em mais de 4000 barramentos. A modelagem hidrodinÃmica utilizada neste estudo a partir de medidas realizadas na interface ZR/ZM em marÃs de quadratura, fevereiro e junho de 2006, e do tipo sizÃgia, setembro de 2005, totalizou vazÃes hÃdricas entre 58 a 183 m3.s-1, no perÃodo avaliado. O tempo de residÃncia (TR) das Ãguas estuarinas mostrou dependÃncia da variabilidade climÃtica anual e inter-anual variando de 3 a 2 horas na estaÃÃo seca, em 2005 e 2006, respectivamente, enquanto que em Ãpoca de chuvas foi igual a 12 horas. Este resultado sugere que o volume de Ãgua doce nÃo à o fator limitante da competÃncia da massa de Ãgua para romper as forÃantes marinhas atuantes na regiÃo, mas a vazÃo hÃdrica total à significativa, principalmente durante a estaÃÃo seca quando o estuÃrio à lixiviado por Ãguas marinhas que aumentam sua capacidade de depuraÃÃo. As maiores salinidades foram observadas nos perÃodos em que o sistema estuarino apresentou menor aporte hÃdrico fluvial, chegando a 36,1 quando o percentual de Ãgua doce foi menor que 15%. O material particulado em suspensÃo (MPS) variou sazonalmente entre 7 e 89,7 mg/L. O MPS em setembro de 2005 e junho de 2006 foi fortemente orgÃnico, enquanto que o MPS coletado em fevereiro de 2006 foi de origem carbonÃtica. As descargas de MPS e de metais no MPS oriundos da bacia de drenagem para o estuÃrio, apresentaram variabilidade sazonal crescente de acordo com o aumento das chuvas e com os maiores valores no perÃodo de maior aporte fluvial. O mesmo padrÃo de comportamento do MPS à observado para as descargas dos metais, tais como; Fe, Al, Mn, Cu e Zn, tendo como exceÃÃo o comportamento do Pb no MPS, que apresentou os maiores valores no perÃodo de domÃnio marinho.
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Millier, Helen Katherine Genevieve Ruth. „Evaluation of the impact of treated wastewaters discharges on river water phosphorus and metal concentrations“. Thesis, Kingston University, 2009. http://eprints.kingston.ac.uk/20406/.
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It is standard practice for sewage treatment plants to discharge treated wastewaters to water-bodies and, in the UK, this has been the custom since the first sewerage system was completed in London around 1865. Before sewerage networks untreated sewage waste was discharged to rivers (wet carriage) or removed from domestic dwellings by "honey wagons" (dry carriage) and taken to rural areas to be used as fertiliser (Adams & Papa, 2000). Wastewater inputs to rivers are governed by discharge consents issued by the Environment Agency in accordance with existing legislation, taking into account the physical and ecological characteristics of the receiving river. However, it has become apparent in recent years that wastewaters may have a detrimental effect on receiving rivers, particularly in terms of nutrients as they frequently discharge phosphorus (P) in concentrations > 1.0 mg P 1[sup]-1. Metals are not specifically removed by the wastewater treatment process and, although their affinity for particulates results in some removal during processing, it is suspected that dissolved metals may be present in treated wastewaters. In 2000, the E.C. introduced the Water Framework Directive, which requires water bodies within member countries to attain "good ecological status" by 2015 in terms of biological and physico-chemical water quality. An umbrella Directive, it combines existing legislation on a range of contaminants including nutrients and metals with additional environmental standards to improve the quality of European waters. The purpose of this study was to consider whether the discharge of treated sewage wastewaters is likely to prevent rivers from achieving the standards required by this legislation. During an eighteen month period, water samples were collected from two second order rivers, the Bourne and Hogsmill, up and downstream of sewage treatment works. Samples were analysed for a range of P species and metals in filtered and unfiltered river water. Ultra-filtration was carried out on a selection of samples, as finer fractions are likely to be more bioavailable. River flow data was used to calculate potential contaminant loads downstream of the input source; this data was compared against published concentrations of agricultural derived P, historically considered the major contributor of P to UK riverine waters. Until the introduction of P removal processing at the Hogsmill, downstream concentrations of all P species in both rivers, were greater than upstream by an order of magnitude. P removal reduced P concentrations in the Hogsmill by more than 60% although they remain significantly greater than upstream. The majority of P occurred as soluble reactive P (SRP), the most bioavailable species, and the continuous nature of wastewaters discharge meant concentrations were high during the growth season. Current P-removal processes may not remove sufficient P to meet quality targets recommended by the U.K. Technical Advisory Group on the Water Framework Directive. Estimated P loads upstream of the wastewaters outflow are < 8 kg SRP day[sup]-1 for both rivers, the combination of increased P concentrations and greater river water volume downstream of the outflow result in estimated P loads of > 45 kg SRP day[sup]-1 in the Bourne and > 80 kg SRP day[sup]-l for the Hogsmill (after P-stripping). Comparison of P export figures from treated sewage wastewaters, calculated using daily load figures, with those from agriculture indicate that in all but the most rural catchments, sewage wastewaters are a greater source of P. Downstream, dissolved metals concentrations were not significantly different from upstream except for As in the Bourne and Pb in the Hogsmill; neither metal exceeded regulatory limits. River sediment from the Hogsmill and Bourne, and two additional rivers receiving sewage wastewaters, the Mole and Blackwater, were analysed for total metals and P. The ability of sediments to release (SRP) was investigated using kinetic release analysis. In the absence of U.K. standards, metals concentrations in sediments were assessed using the US EPA sediment quality guidelines (SQG). A range of metals in sediments from both the Hogsmill and Mole exceeded SQG to the extent that biota was likely to be affected. Although the greatest concentrations of total phosphorus in sediment were found in the Bourne, it is the Hogsmill which exhibits most potential for the release of SRP from sediment to the water column.
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Drake, Chad Walter. „Assessment of flood mitigation strategies for reducing peak discharges in the Upper Cedar River watershed“. Thesis, University of Iowa, 2014. https://ir.uiowa.edu/etd/4617.
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This thesis evaluates the effectiveness of several flood mitigation strategies for reducing peak discharges in the Upper Cedar River Watershed located in northeast Iowa. Triggered by record flooding in June 2008, the Iowa Watersheds Project was formed to evaluate and construct projects for flood reduction. The Upper Cedar was selected as a pilot watershed and a hydrologic assessment was performed to better understand its flood hydrology. Evaluation of different flood mitigation strategies was performed with HEC-HMS, a lumped parameter surface water model. The hydrologic model development is described and the model applications are analyzed.
The HMS model was used in several ways to better understand the flood hydrology of the Upper Cedar River Watershed. First, the runoff potential of the basin was assessed to identify the primary runoff generation mechanisms. Areas with agricultural land use and moderately to poorly draining soils had the highest runoff potential. Following, the model was used to evaluate the impact of several flood mitigation strategies - increased infiltration through land use changes, increased infiltration through soil improvements, and added storage in the watershed to hold runoff temporarily and reduce downstream flood peaks - for different flood frequency events (the 10-, 25-, 50-, and 100-year, 24-hour design rain storms) and the June 2008 flood. Although each scenario is hypothetical and simplified, they do provide benchmarks for the types of reductions physically possible and the effectiveness of strategies relative to one another. In order to reduce the impacts of flooding in the Upper Cedar, a combination of projects that enhance infiltration and/or store excess runoff will be necessary.
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Ayalew, Tibebu Bekele. „Physical basis of the power-law spatial scaling structure of peak discharges“. Diss., University of Iowa, 2015. https://ir.uiowa.edu/etd/1537.
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Key theoretical and empirical results from the past two decades have established that peak discharges exhibit power-law, or scaling, relation with drainage area across multiple scales of time and space. This relationship takes the form Q(A)= $#945;AΘ where Q is peak discharge, A is the drainage area, Θ is the flood scaling exponent, and α is the intercept. Motivated by seminal empirical studies that show that the flood scaling parameters α and Θ change from one rainfall-runoff event to another, this dissertation explores how certain rainfall and catchment physical properties control the flood scaling exponent and intercept at the rainfall-runoff event scale using a combination of extensive numerical simulation experiments and analysis of observational data from the Iowa River basin, Iowa. Results show that Θ generally decreases with increasing values of rainfall intensity, runoff coefficient, and hillslope overland flow velocity, whereas its value generally increases with increasing rainfall duration. Moreover, while the flood scaling intercept is primarily controlled by the excess rainfall intensity, it increases with increasing runoff coefficient and hillslope overland flow velocity. Results also show that the temporal intermittency structure of rainfall has a significant effect on the scaling structure of peak discharges. These results highlight the fact that the flood scaling parameters are able to be estimated from the aforementioned catchment rainfall and physical variables, which can be measured either directly or indirectly using in situ or remote sensing techniques. The dissertation also proposes and demonstrates a new flood forecasting framework that is based on the scaling theory of floods. The results of the study mark a step forward to provide a physically meaningful framework for regionalization of flood frequencies and hence to solve the long standing hydrologic problem of flood prediction in ungauged basins.
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Fowler, Vivienne Frances. „The impacts of chemical discharges on the reproductive biology of the bullhead Cottus gobio and the dipper Cinclus cinclus in the Tamar catchment“. Thesis, University of Exeter, 2011. http://hdl.handle.net/10036/3092.
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It is now well established that a wide range of natural and anthropogenic chemicals present in the aquatic environment have the potential to disrupt the endocrine system of many organisms. In fish, many of these effects appear to be of a feminising nature, including stimulation of vitellogenin production and induction of intersex. In piscivorous birds these so called endocrine disrupting contaminants have been shown to impair reproduction, influencing reproductive behaviour, sex ratio, eggshell thickness and reproductive success. The effects seen in fish have been associated with high levels of oestrogenic activity in the effluent from waste water treatments works (WwTWs), but few studies have focused on the effects of WwTWs effluents on birds. In this thesis, the effects of effluents from WwTWs on fish and birds were investigated in the Tamar catchment, SW England. The work spanned making detailed assessment on the oestrogenic and anti-androgenic activity of 3 WwTWs effluents, using a variety of water sampling techniques and applying both recombinant yeast oestrogen screen (YES) and recombinant yeast androgen screen (anti-YAS) bioassays to quantify the different hormonal activities. A survey was undertaken of the hormonal activities at 13 sites to determine concentrations of contaminants in the surface waters throughout the Tamar catchment, using both recombinant yeast screens and targeted analytical chemistry for specific pollutants (LC/MS-TOF and GCMS). An ELISA was developed to quantify vitellogenin (VTG) in the bullhead (our study fish sentinel) as a biomarker of oestrogen exposure, and evidence of endocrine disruption was investigated in wild populations of the bullhead, Cottus gobio and the dipper, Cinclus cinclus. Macroinvertebrates from upstream and downstream of three WwTW's effluent discharges and from three sampling sites were also sampled as an index of overall water quality in the Tamar catchment, and as an assessment of food availability for the bullheads and dippers. For the studies on the hormonal activities in three WwTWs in the Tamar catchment, samples were collected by both spot and passive sampling; passive samplers (in replicate) were placed in the effluent discharges for a three week period, and collected on days 7, 14 and 21, spot samples were taken simultaneously. Measurement of total oestrogenic and total anti-androgenic activity was conducted using the YES and anti-YAS, respectively. Spot and passive samples were collected from 13 sites within the Tamar catchment (sampling sites were >2 km downstream of effluent discharges). Additionally, liquid chromatography mass spectrometry time-of-flight (LC/MS-TOF) was used to measure the concentration of oestrone (E1), 17β-oestrodiol (E2) and 17α-ethinylestradiol (EE2) in each sample. Gas chromatography mass spectrometry (GCMS) was used to measure the concentration of individual PBDE and PCB congeners in the spot samples only. Levels of oestrogenic and anti-androgenic activity observed in the WwTWs effluent were comparable with those measured in effluents in the UK and in other countries. Surface waters of the Tamar, away from the WwTWs effluent discharges, contained very little oestrogenic activity (<1.1 ng E2 EQs L-1), and anti-androgenic activity was undetectable. Quantification of oestrogenic activity using passive samplers showed an increasing amount of total oestrogenic activity between days 7 and 21 when measured by the both the YES and LC/MS-TOF. Low levels of PBDE congeners 47, 99, 100, 138 and 153 were detected in the spot samples taken from the Tamar catchment, with BDE 47 being the most abundant. In contrast PCBs were undetectable. Neither PBDEs nor PCBs were detected in any of the extracts from the passive samples. No assay was available to measure VTG (one of the most widely used biomarkers of oestrogen exposure in fish) in the bullhead and so an enzyme linked immunosorbant assay (ELISA) was developed for application to studies on wild bullheads in the Tamar catchment. The bullhead vitellogenin (bh-VTG) ELISA was developed successfully, and proved to be sensitive and robust, with a detection range between 10.5 and 300 ng bh-VTG mL-1 (undiluted), comparing favourably with other fish VTG ELISAs. Plasma VTG concentrations measured in male bullheads (collected from the same sites as for the water samples) ranged from below the limit of detection to 990 ng bh-VTG mL-1. Whether these upper levels in the range reflected VTG induction was difficult to conclude. Because of this controlled caged exposures with bullheads and trout were used to assess the relative levels of oestrogenicity in two key WwTWs effluent discharges and to determine the response sensitivity of the bullheads (and trout) to those effluents. These controlled exposures found no responses in plasma VTG in bullheads (ranging between 126 and 934 ng bh-VTG mL-1) suggesting a lack of sensitivity for VTG induction. This was supported by the inability to induce VTG in fish held in the laboratory and treated with steroidal oestrogens. For the effluent exposures on the caged rainbow trout, it was also found that there was no significant induction of VTG, a species normally sensitive to oestrogens. These findings may indicate that the fish were highly stressed due to the river being in spate and the movement of the cages during the controlled exposures. It may also be the case, however, that the use of immature female rainbow trout with a highly variable baseline plasma VTG concentration may prevent any detection of a response. There were no signs of sexual disruption in any of the gonads analysed from either male or female wild bullheads, demonstrating that any hormonal activity present in the catchment away from the WwTWs effluents was not sufficient to induce adverse effects on reproductive development. An interesting feature noted in the male testes of the bullheads was the presence of spermatid masses, which have been recorded in 10 other Cottidae species, but not previously in the bullhead. For the studies on dippers, eggs were collected from the nests of breeding dippers to measure for sperm numbers and morphology from sperm trapped in the perivitelline membrane (PVM), and the yolks were analysed for PBDEs, PCBs and organochlorine pesticides (OCPs) by GCMS, for E1, E2, and EE2 by LC/MS-TOF. Eggs of the dipper were collected from nests at the 13 sampling sites, plus an additional three sites and over three years of field study. The number of sperm trapped in the PVM ranged between three and 188, with a mean of 68.78 ± 8.78 SE. Dipper sperm had not previously been characterised, and was found to be similar to other passerine sperm, in that the head was helical, complemented by a mitochondrial helix or keel, which continued in a spiral around the flagellum. Sperm were classed as ‘abnormal’ if they did not adhere to this typical structure. No assessment of motility could be made in relation to the structural abnormalities seen. Contaminants in the dipper eggs were dominated by BDE 99, an unusual result considering the dippers aquatic lifestyle. PCB 153 was the most common PCB, and p,p’-DDE was the most abundant OCP; all other pesticides tested were below the limit of detection, as were the levels of all three steroid oestrogens. There was inter- and intra-nest variability between contaminant burdens in all eggs as well as the number of sperm trapped in the PVM, but there was no relationship between sperm number and the level of contaminant loadings in the eggs. There were no correlations between contaminants and oestrogenic activity measured in the water samples, and plasma VTG concentrations in bullheads or contaminant loadings in eggs, or indeed sperm number. Analysis of macroinvertebrate assemblages proved that the surface waters of the Tamar catchment were of ‘very good’ quality, even in close proximity to WwTWs effluent discharges.
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Klingner, William. „The effects of increased infiltration and distributed storage on reducing peak discharges in an agricultural Iowa watershed: the Middle Raccoon River“. Thesis, University of Iowa, 2014. https://ir.uiowa.edu/etd/4664.
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The devastating Floods throughout Iowa in 2008 caused homes to be lost, people to be displaced, and cost billions in economic damages. This left State Officials pondering how to limit the damages of large magnitude floods in the future. From the legislative sessions following this tragedy came the Iowa Flood Center and funding through the Department of Housing and Urban Development (among others) to begin the Iowa Watersheds Project. The project was tasked with the planning, implementation and evaluation of watershed projects to lessen the severity and frequency of flooding in Iowa. One test watershed studied was the Middle Raccoon River watershed in West Central Iowa.
To study the impacts of basin-wide flood mitigation strategies on the Middle Raccoon River watershed, the hydrologic modeling software HEC-HMS was used in conjunction with the geographic analysis software, ArcGIS. A model was developed and calibrated to best represent the observed hydrologic response at USGS stream gages located at Bayard, IA and Panora, IA. Once complete, a series of flood mitigation techniques were applied to the watershed model, and run with the 10-, 25-, 50-, and 100-year SCS design storms. These techniques include increasing infiltration by modifying land use, and applying a distributed storage system (ponds). Both practices are shown to have the ability to reduce peak discharge, from 4 percent to 56 percent, depending on the location in the watershed, the severity of the design storm, and the extent of the flood mitigation technique.
Although research describing the effects of distributed storage and increased infiltration currently exist, this study details the process in which these effects can be modeled in a heavily agricultural Iowa watershed using a simplified lumped parameter model (HEC-HMS). With recent major flooding events in Iowa, the methods and tools in this report will be valuable in predicting the effectiveness of flood projects prior to project construction.
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Brown, Philip [Verfasser], und H. [Akademischer Betreuer] Horn. „Impact of antibiotics and particulate matter from wastewater discharges on the abundance of antibiotic resistance genes in river sediments / Philip Clifford Brown ; Betreuer: H. Horn“. Karlsruhe : KIT-Bibliothek, 2019. http://nbn-resolving.de/urn:nbn:de:101:1-2019101607270420968652.
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Brown, Philip Clifford [Verfasser], und H. [Akademischer Betreuer] Horn. „Impact of antibiotics and particulate matter from wastewater discharges on the abundance of antibiotic resistance genes in river sediments / Philip Clifford Brown ; Betreuer: H. Horn“. Karlsruhe : KIT-Bibliothek, 2019. http://d-nb.info/119713896X/34.
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Bleackley, Natalie Anne. „Biology of common bully (Gobiomorphus cotidianus)“. The University of Waikato, 2008. http://adt.waikato.ac.nz/public/adt-uow20080320.150044/index.html.
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Orem, Caitlin A., und Jon D. Pelletier. „Constraining frequency–magnitude–area relationships for rainfall and flood discharges using radar-derived precipitation estimates: example applications in the Upper and Lower Colorado River basins, USA“. COPERNICUS GESELLSCHAFT MBH, 2016. http://hdl.handle.net/10150/622343.
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Flood-envelope curves (FECs) are useful for constraining the upper limit of possible flood discharges within drainage basins in a particular hydroclimatic region. Their usefulness, however, is limited by their lack of a well-defined recurrence interval. In this study we use radar-derived precipitation estimates to develop an alternative to the FEC method, i.e., the frequency–magnitude–area-curve (FMAC) method that incorporates recurrence intervals. The FMAC method is demonstrated in two well-studied US drainage basins, i.e., the Upper and Lower Colorado River basins (UCRB and LCRB, respectively), using Stage III Next-Generation-Radar (NEXRAD) gridded products and the diffusion-wave flow-routing algorithm. The FMAC method can be applied worldwide using any radar-derived precipitation estimates. In the FMAC method, idealized basins of similar contributing area are grouped together for frequency–magnitude analysis of precipitation intensity. These data are then routed through the idealized drainage basins of different contributing areas, using contributing-area-specific estimates for channel slope and channel width. Our results show that FMACs of precipitation discharge are power-law functions of contributing area with an average exponent of 0.82 ± 0.06 for recurrence intervals from 10 to 500 years. We compare our FMACs to published FECs and find that for wet antecedent-moisture conditions, the 500-year FMAC of flood discharge in the UCRB is on par with the US FEC for contributing areas of ∼ 102 to 103 km2. FMACs of flood discharge for the LCRB exceed the published FEC for the LCRB for contributing areas in the range of ∼ 103 to 104 km2. The FMAC method retains the power of the FEC method for constraining flood hazards in basins that are ungauged or have short flood records, yet it has the added advantage that it includes recurrence-interval information necessary for estimating event probabilities.
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Wharton, Geraldene. „River discharge estimated from river channel dimensions in Britain“. Thesis, University of Southampton, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.252678.
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Chiejina, Chidinma. „Identifying misconnection hotspots using coliforms and biofilm communities“. Thesis, University of Hertfordshire, 2016. http://hdl.handle.net/2299/17352.
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Sewage misconnections currently pose severe threats to water quality especially in urban areas in the UK. These misconnections lead to the discharge of untreated wastewater into receiving watercourses via surface water outfalls. Regular discharges from this source could lead to these watercourses failing to meet standards set by the Water Framework Directives. Despite the impacts resulting from this urban diffuse pollutant source, research into this area is limited. The study area is the River Lee, which is known to experience issues with water quality especially within the heavily urbanized lower Lee section. Misconnections are one of the major contributors to the poor water quality status of the River. In this study, the Lee was investigated using several parameters. The approach involved the monitoring of coliform bacteria to detect outfalls where misconnections were likely, then biofilm samples below selected outfalls were used for both clean and polluted sites to look for community types. Results showed severe pollution within some sections of the River particularly within the lower Lee. Pymmes Brook was used as a case study, both coliform bacteria and biofilm communities below outfalls were further investigated for clean and polluted sites. Results from the Pymmes Brook study also showed that this watercourse was experiencing severe issues with water quality, with elevated levels of coliform bacteria identified below polluted outfalls. Biofilm community data obtained during the pilot and experimental phases of study were analyzed using a range of multivariate techniques. Results of the analysis showed consistent x patterns in community structure within sites with similar water quality, with indicator species identified. Communities below polluted outfalls were composed mainly of species tolerant of organic pollution thus indicating a response of communities to misconnection discharges. Currently, the identification of misconnections are carried out through trackbacks, a process which is expensive and time consuming. During this study an inexpensive and rapid approach is proposed for assessing misconnections within a catchment. Using this method, misconnection hotspots are mapped out using coliform bacteria and biofilm communities. Using catchment data and predicted coliform bacteria from enumerated counts, misconnections within these hotspots are assessed. Having tested this approach on Pymmes Brook, a tributary of the River Lee, the results obtained were promising. Pending further verification, this system provides an economical and rapid tool for the assessment of misconnections within a catchment.
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Mion, Joseph Benjamin. „River Discharge Drives Differential Survival of Larval Walleye“. The Ohio State University, 1996. http://rave.ohiolink.edu/etdc/view?acc_num=osu1393069060.
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Bowes, Michael John. „Phosphorus dynamics within large river catchments : interactions with sediment, biota and river discharge“. Thesis, University of Portsmouth, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.438859.
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Yu, Yingying. „Numerical Study of the Brisbane River Plume in Moreton Bay, Australia“. Thesis, Griffith University, 2011. http://hdl.handle.net/10072/365899.
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Coastal rivers that discharge freshwater, with sediment and nutrients, into the ocean often
generate a buoyant river plume in the vicinity of the river mouth. The river plume, driven
by river floods, has become a significant environmental issue, which may be increasing
in occurrence and severity as a consequence of climate change. The excess runoff created
by floods has the capacity to carry a large amount of sediment and contaminants from
land-based human activities into the coastal and shelf waters.
The purpose of this research was to examine the dynamic and transport characteristics of
the Brisbane River plume using a numerical model. It also sought to answer the following
questions: 1) What is the seasonal behaviour of the Brisbane River plume, particularly
during flood seasons, and 2) What are the impacts of external forces acting on the
Brisbane River plume? It is anticipated that the knowledge gained from this research will
promote a better understanding of the Brisbane River plume behaviour in Moreton Bay.Thesis (Masters)
Master of Philosophy (MPhil)
Griffith School of Engineering
Science, Environment, Engineering and Technology
Full Text
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Bryan, Brynne L. (Brynne Lee). „Plankton Community Response to Dechorination of a Municipal Effluent Discharged into the Trinity River“. Thesis, University of North Texas, 1994. https://digital.library.unt.edu/ark:/67531/metadc278689/.
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Chorine is used by the Village Creek Waste Water Treatment Plant to kill pathogenic microorganisms prior to discharge of the effluent into the Trinity River. The residual chlorine in the river impacted aquatic life prompting the U.S. Environmental Protection Agency in December 1990 to require dechlorination using sulfur dioxide. One pre-dechlorination and four post-dechlorination assessments of phytoplankton, periphyton, and zooplankton communities were conducted by the Institute of Applied Sciences at the University of North Texas. Dechlorination had no effect on the phytoplankton community. The periphyton community exhibited a shift in species abundance with a more even distribution of organisms among taxa. No change occurred in zooplankton species abundance, however, there was a decrease in zooplankton density following dechlorination.
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McKay, Daniel E. „Modeling Discharge from the Upper Raccoon Creek River, Ohio“. Ohio University / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1493206968336602.
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Dangerfield, Helen Rebecca. „A study of channel geometry-discharge relationships in semi-natural British rivers as a basis for river restoration and management“. Thesis, Queen Mary, University of London, 1999. http://qmro.qmul.ac.uk/xmlui/handle/123456789/1707.
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River restoration has developed over the last three decades in the context of a more holistic approach to river management. One of the most important issues facing river managers is the design of river channel dimensions. The successful design of cross-sectional dimensions requires an understanding of river channel stability and the sensitivity of rivers to change. A need for more work in this field was identified. This research investigates the variability of downstream channel geometry discharge as a basis for assessing river channel stability and sensitivity to change. A national database containing 124 semi-natural UK river sites is used to develop a linear regression model relating bankfull width with dominant discharge. The magnitude and direction of standardised residual values from the model are then investigated in terms of their geomorphological significance. Particular groups of residual values are found to be related to specific controlling factors. Extreme high magnitude positive residuals (>1.0) are dominated by baseflow dominated chalk rivers. Negative residuals (>-0.5 to -1.0) are found to have a bedrock control. Other controlling factors operating at a local scale, including bank materials, bed materials and vegetation cannot be identified as having an exclusive influence on residual values. The variability in channel geometry - discharge relationships is broadly indicative of river channel adjustment based results from the field study of a subset of 50 sites. Residuals closest to the regression line demonstrate active or inactive stability and negative and positive residuals show a tendency towards erosional and depositional processes respectively. A study of temporal changes in a subset of 16 rivers supports these findings whilst highlighting the importance of the mutual adjustment of channel parameters through time. To investigate river channel adjustment at a reach downstream within a single river, a more detailed catchment study forms the second part of the research. Three contrasting catchments were used to investigate the implications of changing downstream channel geometry and stability on river channel adjustment at a reach. The results reinforce the importance of assessing the mutual adjustment of width, depth, and gradient to identify the dominant form of adjustment at a reach. Drainage basin form was found to exert an important control on channel geometry adjustment both laterally and longitudinally downstream. The results support the findings from the national model which show that stability is a function of complex combination of controlling factors which are represented by the residual values. River channel stability can be viewed as a function of the flow regime related to local environmental factors. The variability of channel geometry - discharge relationships does appear to represent the direction of river channel adjustment, but stability at a reach must be evaluated in the context of the adjustment of downstream parameters related to both catchment and local scale controls.
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Hoffman, Frederick A. „Carbon, Nitrogen, and Phosphorus Discharge from the Altamaha River, Georgia“. W&M ScholarWorks, 1989. https://scholarworks.wm.edu/etd/1539617600.
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Knight, Deborah Ann. „The influence of discharge variability on river channel width : a field and laboratory study“. Thesis, Keele University, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.265644.
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Azevedo, Jose Roberto Goncalves de. „Water resources and global warming for the Sao Francisco River in Brazil“. Thesis, University of Southampton, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.297629.
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King, Tyler V. „Quantifying Dominant Heat Fluxes in an Arctic Alaskan River with Mechanistic River Temperature Modeling“. DigitalCommons@USU, 2018. https://digitalcommons.usu.edu/etd/7224.
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Temperatures strongly affect physical, chemical, and biological processes in rivers and streams. The processes that influence river temperatures are known across most geographic regions, but the relative importance varies significantly. Little is known about what controls water temperature Arctic rivers, limiting our ability to understand the impacts of climate change. This dissertation addresses this knowledge gap by incorporating field measurements with river temperature modeling to estimate the relative importance of key factors that affect Arctic river temperatures. Results indicate that shortwave radiation (e.g., sunlight) and net longwave radiation are significant throughout an Arctic watershed in all flow conditions. In areas where the river is smaller, however, exchange of water with the riverbed and inputs of water from the landscape become significant under low-flow and high-flow conditions, respectively. Additional field observations and modeling were used to quantify the water and heat exchanges between the river and the riverbed. These heat exchanges were found to cool the river and reduce the daily range of temperatures. To better estimate the flow of water from the landscape to the river, a new method for estimating river flow was developed using high-resolution aerial imagery. This method allows us to estimate river flow without depending on field measurements, and presents a potential solution to barriers in performing river temperature modeling in other parts of the Arctic.
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Petchprayoon, Pakorn. „The effects of urbanization on river discharge and river flood potential in a central northern watershed, Thailand“. Connect to online resource, 2008. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:1453537.
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Wulf, Hendrik. „Seasonal precipitation, river discharge, and sediment flux in the western Himalaya“. Phd thesis, Universität Potsdam, 2011. http://opus.kobv.de/ubp/volltexte/2012/5790/.
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Rainfall, snow-, and glacial melt throughout the Himalaya control river discharge, which is vital for maintaining agriculture, drinking water and hydropower generation. However, the spatiotemporal contribution of these discharge components to Himalayan rivers is not well understood, mainly because of the scarcity of ground-based observations. Consequently, there is also little known about the triggers and sources of peak sediment flux events, which account for extensive hydropower reservoir filling and turbine abrasion. We therefore lack basic information on the distribution of water resources and controls of erosion processes.
In this thesis, I employ various methods to assess and quantify general characteristics of and links between precipitation, river discharge, and sediment flux in the Sutlej Valley. First, I analyze daily precipitation data (1998-2007) from 80 weather stations in the western Himalaya, to decipher the distribution of rain- and snowfall. Rainfall magnitude frequency analyses indicate that 40% of the summer rainfall budget is attributed to monsoonal rainstorms, which show higher variability in the orogenic interior than in frontal regions. Combined analysis of rainstorms and sediment flux data of a major Sutlej River tributary indicate that monsoonal rainfall has a first order control on erosion processes in the orogenic interior, despite the dominance of snowfall in this region.
Second, I examine the contribution of rainfall, snow and glacial melt to river discharge in the Sutlej Valley (s55,000 km2), based on a distributed hydrological model, which covers the period 2000-2008. To achieve high spatial and daily resolution despite limited ground-based observations the hydrological model is forced by daily remote sensing data, which I adjusted and calibrated with ground station data. The calibration shows that the Tropical Rainfall Measuring Mission (TRMM) 3B42 rainfall product systematically overestimates rainfall in semi-arid and arid regions, increasing with aridity. The model results indicate that snowmelt-derived discharge (74%) is most important during the pre-monsoon season (April to June) whereas rainfall (56%) and glacial melt (17%) dominate the monsoon season (July-September). Therefore, climate change most likely causes a reduction in river discharge during the pre-monsoon season, which especially affects the orogenic interior.
Third, I investigate the controls on suspended sediment flux in different parts of the Sutlej catchments, based on daily gauging data from the past decade. In conjunction with meteorological data, earthquake records, and rock strength measurements I find that rainstorms are the most frequent trigger of high-discharge events with peaks in suspended sediment concentrations (SSC) that account for the bulk of the suspended sediment flux. The suspended sediment flux increases downstream, mainly due to increases in runoff. Pronounced erosion along the Himalayan Front occurs throughout the monsoon season, whereas efficient erosion of the orogenic interior is confined to single extreme events.
The results of this thesis highlight the importance of snow and glacially derived melt waters in the western Himalaya, where extensive regions receive only limited amounts of monsoonal rainfall. These regions are therefore particularly susceptible to global warming with major implications on the hydrological cycle. However, the sediment discharge data show that infrequent monsoonal rainstorms that pass the orographic barrier of the Higher Himalaya are still the primary trigger of the highest-impact erosion events, despite being subordinate to snow and glacially–derived discharge. These findings may help to predict peak sediment flux events and could underpin the strategic development of preventative measures for hydropower infrastructures.Regen, Schnee- und Gletscherschmelze speisen die Flüsse des Himalajas, die eine große Bedeutung für die Landwirtschaft, Trinkwasserversorgung und Wasserkraftnutzung in Südasien aufweisen. Welchen Anteil die einzelnen Abflusskomponenten am Gesamtabfluss in Raum und Zeit besitzen, ist jedoch kaum quantifiziert, da es in der entlegenen Region an Bodenmessstationen mangelt. Aus diesem Grund ist auch wenig über die Auslöser und Herkunftsgebiete von hohen Sedimentaustragsereignissen bekannt, die im erheblichen Maße dazu beitragen, dass die Kapazität vonWasserkraftreservoiren abnimmt undWasserkraftturbinen abradieren. Daher fehlen bisher grundlegende Informationen zur räumlichen Verteilung von Wasserressourcen und zu den Ursachen von Erosionsprozessen. In dieser Arbeit benutze ich verschiedene Methoden um die Eigenschaften von und die Beziehungen zwischen Niederschlag, Abflussmenge und Sedimentaustrag im Sutlej-Tal zu untersuchen. In einer ersten Studie analysiere ich Tagesniederschläge (1998-2007) von 80 Wetterstationen aus dem westlichen Himalaja, um die räumliche Verteilung von Regen- und Schneeniederschlägen zu charakterisieren. Die weitere Analyse der Magnituden-Häufigkeitsverteilung von Regenfällen zeigt, dass 40% der sommerlichen Niederschläge auf monsunale Starkregenereignisse zurückgehen, die eine höhere Variabilität im Gebirgsinneren aufweisen als an der Gebirgsfront. Die Kombination von Niederschlagsdaten mit Sedimentaustragsdaten für einen der größten Zuflüsse des Sutlejs zeigt, dass monsunaler Niederschlag der primäre Auslöser von Erosionsprozessen im Gebirgsinneren ist, ungeachtet größerer Abflussmengen durch Schnee- und Gletscherschmelze. In einer zweiten Studie untersuche ich den Beitrag von Regen, Schnee- und Gletscherschmelze zur Abflussmenge im Sutlej-Tal (s55.000 km2) mit Hilfe eines hydrologischen Modells für den Jahreszeitraum 2000-2008. Um trotz der begrenzten Bodenmessungen eine hohe räumliche und zeitliche Auflösung zu erzielen, basiert das Modell auf täglichen Fernerkundungsdaten, die ich mit allen verfügbaren Bodenstationsdaten kalibriert und an diese angepasst habe. Die Kalibrierung zeigt, dass das Regenniederschlagsprodukt 3B42 der „Tropical Rainfall Measuring Mission“ (TRMM) den Bodenniederschlag in den semi-ariden bis ariden Gebirgsregionen mit zunehmender Trockenheit systematisch überschätzt. Die Modellierungsergebnisse verdeutlichen, dass die Schneeschmelze den bedeutendsten Beitrag zur Abflussmenge (74 %) zwischen April und Juni aufbringt, während Regen (56%) und Gletscherschmelze (17%) die Monsunsaison (Juli-September) prägen. Daher ist anzunehmen, dass der Klimawandel zu einer Verringerung der Abflussmenge zwischen April und Juni führen wird, was sich besonders auf das Gebirgsinnere auswirkt. In einer dritten Studie untersuche ich mit Hilfe von täglichen Messdaten der letzten Dekade die Ursachen und Eigenschaften des Sedimentaustrags in verschiedenen Bereichen des Sutlej-Einzugsgebietes. Auf der Grundlage von meteorologischen Daten, Erdbebenaufzeichnungen und Gesteinsfestigkeitsmessungen identifiziere ich Starkregenereignisse als häufigste Ursache für extreme Erosionsereignisse, die einen Großteil des gesamten Sedimentaustrags ausmachen. Großräumig betrachtet nimmt der Sedimentaustrag flussabwärts zu, was hauptsächlich auf den Anstieg der Abflussmenge zurückzuführen ist. Zur Monsunzeit treten Erosionsprozesse entlang der Himalajafront besonders häufig auf, während im Gebirgsinneren die Erosion auf einzelne Extremereignisse beschränkt ist. Die Ergebnisse dieser Arbeit untersteichen die Bedeutung von Schnee- und Gletscherschmelze im westlichen Himalaja, in dem große Gebiete nur vereinzelt von monsunalen Niederschlägen erreicht werden. Diese Gebiete sind daher besonders anfällig für den Klimawandel mit weitreichenden Konsequenzen für den Wasserhaushalt in der Region. Die Analyse von Sedimentaustragsdaten zeigt jedoch, dass vereinzelte monsunale Regenstürme, welche die topographische Barriere des Himalaja überqueren, die primäre Ursache von extremen Erosionsereignissen sind, trotz der größeren Abflussmengen von Schnee- und Gletscherschmelze im Gebirgsinneren. Diese Ergebnisse können dazu beitragen, große Erosionsereignisse vorherzusagen und vorbeugende Maßnahmen zum Schutz von Wasserkraftanlagen zu entwickeln.
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White, Paul Andrew. „Detection, discharge and ecological behaviour of genotoxic organic contaminants in the St. Lawrence and Saguenay rivers“. Thesis, McGill University, 1995. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=40281.
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The goal of this thesis was to examine the sources and ecological behaviour of genotoxic organics in the St. Lawrence river system. A rapid and effective version of the SOS Chromotest was developed to accomplish the task of genotoxicity assessment. The method, validated with standard reference materials, is particularly well suited to complex environmental extracts. The endpoint investigated throughout the thesis, SOS genotoxicity, is empirically related to more familiar endpoints such as mutagenicity and carcinogenicity. Analyses of literature data confirmed correlations between SOS genotoxicity and both Ames/Salmonella mutagenicity and animal carcinogenicity. Analyses of industrial and municipal wastewaters revealed that organic and inorganic chemical production facilities, metal refining and founding facilities and petroleum refineries release high potency wastes. Loading values indicate that low potency sources (e.g. municipal wastewater and pulp & paper facilities) often have exceptionally high loadings. A substantial portion (2.3-99.8%) of industrial genotoxins are associated with suspended particulates. Sorption partition efficients (K$ sb{ rm d-genotox}$) indicate that municipal wastewater and pulp & paper facilities release particularly soluble genotoxins. Extracts of suspended particulate matter collected near industrial discharges are direct-acting. Bottom sediment extracts are less potent and usually require S9 metabolic activation. Genotoxicity of both bottom sediment and suspended particulates are empirically related to the genotoxicity of regional industrial emissions. Direct-acting substances in the water column appear to be less stable and may be converted to more stable pro-genotoxic substances present in the bottom sediments. A mass balance of genotoxicity for St. Lawrence surface waters revealed that domestic, rather than industrial sources make the largest contribution to observed genotoxicity. The importance of domestic wastes was confirmed
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Agafonov, Leonid I., David M. Meko und Irina P. Panyushkina. „Reconstruction of Ob River, Russia, discharge from ring widths of floodplain trees“. ELSEVIER SCIENCE BV, 2016. http://hdl.handle.net/10150/622663.
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The Ob is the third largest Eurasian river supplying heat and freshwater to the Arctic Ocean. These inputs influence water salinity, ice coverage, ocean temperatures and ocean circulation, and ultimately the global climate system. Variability of Ob River flow on long time scales is poorly understood, however, because gaged flow records are short. Eleven tree-ring width chronologies of Pinus sibirica and Larix sibirica are developed from the floodplain of the Lower Ob River, analyzed for hydroclimatic signal and applied as predictors in a regression model to reconstruct 8-month average (December-July) discharge of the Ob River at Salekhard over the interval 1705-2012 (308 yrs). Correlation analysis suggests the signal for discharge comes through air temperature: high discharge and floodplain water levels favor cool growing-season air temperature, which limits tree growth for the sampled species at these high latitudes. The reconstruction model (R-2 = 0.31, 1937-2009 calibration period) is strongly supported by cross validation and analysis of residuals. Correlation of observed with reconstructed discharge improves with smoothing. The long-term reconstruction correlates significantly with a previous Ob River reconstruction from ring widths of trees outside the Ob River floodplain and extends that record by another century. Results suggest that large multi-decadal swings in discharge have occurred at irregular intervals, that variations in the 20th and 21st centuries have been within the envelope of natural variability of the past 3 centuries, and that discharge data for 1937-2009 underestimate both the variability and persistence of discharge in the last 3 centuries. The reconstruction gives ecologists, climatologists and water resource planners a long-term context for assessment of climate change impacts.
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Xu, Kejun. „Total suspended solids, discharge, conductivity, and nutrients in three watersheds of the Upper White River, IN“. Virtual Press, 2004. http://liblink.bsu.edu/uhtbin/catkey/1307378.
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Three watersheds of Upper White River were chosen for this study. Stream samples were tested for total suspended solids and conductivity. Fourteen percent of the total suspended solids samples were above 80 mg L-1 which can cause negative effects to aquatic life. Total suspended solids results were tested with a general linear model and in linear regressions with discharge and nutrients. Conductivity results were tested with a general linear model. Concentrations of the total suspended solids were significantly related to watershed, Julian date, the interaction of watershed and Julian date, and discharge. Increasing total suspended solids concentrations were significantly related to increasing concentrations of orthophosphate, nitrate, and ammonia. Conductivity levels were significantly related to watershed, location within watershed, and Julian date. Total suspended solids, discharge, and nutrient concentrations were high in the spring, but decreased in the following seasons.Department of Natural Resources and Environmental Management
32
Kim, Yeonsu. „Probabilistic Estimation of River Discharge Considering Channel Characteristics Uncertainty with Particle Filters“. 京都大学 (Kyoto University), 2013. http://hdl.handle.net/2433/180482.
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Gildow, Marie C. „Evaluating Fertilizer Application Practices to Reduce Phosphorus Discharge from the Maumee River“. The Ohio State University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=osu1437400849.
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Bustros-Lussier, Elyse. „Identifying deep-groundwater discharge in rivers of eastern Ontario“. Thesis, University of Ottawa (Canada), 2008. http://hdl.handle.net/10393/27579.
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Interactions between surface water systems and groundwater systems are poorly understood. This research focuses on the surface water/groundwater interactions that use an electric conductivity and temperature (EC&T) drag probe in the Raisin River and South Nation Watershed.
To find groundwater seepages into rivers, a Reelogger Model 2001 probe (Solinst Canada Ltd) was dragged at the sediment-water interface to measure EC&T for several reaches of the Raisin River, the Castor River, the East Castor and the South Nation River. GPS position data was collected at the same time as the EC&T measurements which allows the data to be input into a GIS database for management decisions. During the summer, groundwater typically had higher EC and lower T values than the surface water, and so increases in EC occurring along with lower water temperatures were inferred to be deep-groundwater discharge locations. High EC values can be explained either by deep groundwater discharge (seeps) or by local anthropogenic loading of sediments into the river. In rivers with low permeability clay streambeds very few locations of significant discharge were detected using this method. The most significant discharge area, called the "Swimming Hole" by local residents, was surveyed at large and small scale and groundwater seepage was found to be present along the shore and in the middle. However, the EC&T probe appears to have identified relatively high flux discharge zones in the Castor and East Castor River at locations where highly permeable eskers cross the rivers. The survey identified approximately a 50 m area along the Castor river and a 100m area along the East Castor River where EC values were as high as 2000 muS/cm and temperature as low as 11°C. They were investigated and fluxes quantified by installing and testing piezometers and deploying seepage meters.
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Barnard, M. M. „Discharge measurement at natural controls in Western Cape rivers“. Thesis, Stellenbosch : Stellenbosch University, 2003. http://hdl.handle.net/10019.1/53395.
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Thesis (MEng)--University of Stellenbosch, 2003.ENGLISH ABSTRACT: This study sets out to explore the possibilities and accuracy of flow measurement at natural controls, focussing specifically on Western Cape cobble-bed rivers. These rivers are regarded as being difficult in terms of flow measurement, mostly due to their large scale roughness and very turbulent and uneven flows. The aim is to determine a system through which various types of natural controls can be calibrated, by establishing a relationship between the discharge coefficient and the physical characteristics of each control type. This was achieved by conducting an extensive field investigation, focussing on the identification and gauging of both critical and uniform natural controls. Two types of critical controls were identified and investigated, namely step-pool controls and horizontal constriction controls as well as one type of uniform flow control, namely the plane bed control. Step-pool controls were found to be very robust controls which provided efficient critical controls for a wide range of flows. Horizontal constriction controls proved to be reasonably accurate measurement sites and, because of their physical characteristics, they are able to measure the full range of flows from low to flood flows. Uniform controls are widely used for flow measurements on deep rivers, but such measurements become highly unreliable when flow depths are small and bed roughness high as is the case with cobble-bed rivers. Under conditions of high roughness, generally speaking critical controls can be calibrated more accurately than uniform controls and are therefore to be preferred. The field study was followed by a series of laboratory tests, focussing on horizontal constriction controls. Calibration equations were derived by which the discharge coefficient value can be determined for a given constriction ratio and upstream energy head. Results from both the fieldwork and laboratory work were analysed and integrated to determine a calibration system applicable to natural controls in Western Cape cobbleand boulder-bed rivers. Reasonably accurate values of the discharge coefficients for different types of natural controls were established, which should be widely applicable. Additionally, guidelines were drawn up for the measurement of flow at natural controls, to be used by both engineers and non-engineers. Discharge measurement at natural controls in the Western Cape was found to be a viable and reasonably accurate way of determining river discharge. It proves to be an environmentally acceptable way of measurement, using the natural river characteristics rather than seriously interfering with them or damaging them. These advantages make discharge measurement at natural controls a promising means of determining river discharge in the future.
AFRIKAANSE OPSOMMING: Die beste posisie vir vloeirneting in riviere is waar die topografie van die rivier 'n unieke verhouding tussen die deurstroming en die water diepte bewerkstellig. Hierdie studie ondersoek die uitvoerbaarheid en akkuraatheid van vloeirneting by natuurlike kontroles met die fokus op Wes-Kaapse spoelklip riviere. Vloeirneting in spoelklip riviere word as baie ingewikkeld beskou weens die grootte van die bedpartikels relatieftot die vloeidiepte en gevolglike onewe, turbulente vloeie. Die doel van die studie was om 'n stelsel te ontwikkel waardeur verskillende tipes natuurlike kontroles gekalibreer kan word deur verwantskappe te bepaal tussen die deurstromings koëffisiënt en die stroom-op energie hoogte. Bogenoemde is bepaal met behulp van 'n uitgebreide veldstudie waarin die hoof tipes natuurlike kontroles, nl. die kritiese vloei kontrole en die uniforme vloei kontrole, geidentifiseer en gekalibreer is. Twee tipes kritiese vloei kontroles is ondersoek, naamlik die trap-poel ("step-pool") kontrole en die horisontale vernouing kontrole. Daar is bevind dat beide die trap-poel kontrole en die horisontale vernouing baie effektiewe kritiese kontroles is, waarmee 'n wye reeks van vloeie gemeet kan word. Uniforme vloei kontroles word algemeen vir vloeimeting in diep vloeiende riviere gebruik, maar sulke metings word hoogs onbetroubaar wanner die vloeidiepte klein is relatief tot die partikel grootte van die rivierbed, soos in die geval van spoelklip riviere. Onder hierdie omstandighede kan kritiese kontroles in die algemeen meer akkuraat gekalibreer word en word hul gevolglik bo uniforme vloei kontroles verkies. Die veldstudie is gevolg deur 'n reeks laboratorium toetse, wat fokus op die horisontale vernouing kontrole. Kalibrasie vergelykings is afgelei waarmee die deurstromings koëffisient vir 'n gegewe stroom-op energiehoogte en vernouings-verhouding bereken kan word. Resultate van beide die veldstudie en die laboratorium toetse is geanaliseer en geïntegreer om 'n kalibrasie stelsel te bepaal wat van toepassing is op natuurlike kontroles in Wes-Kaapse spoelklip riviere. Aanvaarbare waardes vir die deurstromings koëffisiente vir verskeie tipes natuurlike kontroles is bepaal, wat algemeen toepasbaar behoort te wees. Riglyne vir die meting van riviervloei by natuurlike kontroles is opgestel vir die gebruik deur beide ingenieurs en nie-ingenieurs. Vloeimeting deur middel van natuurlike kontroles is 'n lewensvatbare metingsmetode waarmee riviervloei redelik akkuraat bepaal kan word. Dit is 'n omgewingsaanvaarbare metings metode wat die natuurlike karakter van die rivier gebruik, eerder as om ernstig daarmee in te meng of dit te beskadig. Hierde positiewe eienskappe maak vloeimeting deur middel van natuurlike kontroles 'n belowende metingsmetode vir die toekoms.
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Carlin, Mattia. „The response of river bar topography to the hydrological flow regime“. Doctoral thesis, Università degli studi di Trento, 2021. http://hdl.handle.net/11572/312573.
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Alternate bars are large-scale bedforms characterised by an ordered sequence of scour zones and depositional diagonal fronts alternating along channel banks, which are typical of straight channelized rivers. Due to their high relief and migration properties, they represent a problem in river management, because they affect navigation, increase the flooding risk and interact with instream structures. For this reason, in the last decades many studies took the challenge of defining suitable criteria able to describe their morphometric properties. Theoretical, experimental and numerical works have clearly demonstrated that bar occurrence is a threshold process governed by the width-to-depth ratio of the channel, β. If this parameter exceeds a critical threshold, βcr, an instability mechanism amplifies the riverbed perturbations occurring due to the effect of the turbulent flow on the cohesionless riverbed, leading to the spontaneous growth of finite amplitude bars. Under steady flow conditions, alternate bars achieve an equilibrium configuration, whose amplitude value is related to the difference β-βcr. Much less information is available to describe bar characteristics under variable flow conditions, when the width-to-depth ratio changes in time and the amplitude of bars evolves depending on the duration and the shape of the hydrograph. The effect of a single idealized flood on bar amplitude evolution was successfully described by the weakly nonlinear model of Tubino (1991), which was able to capture the trajectory of bar amplitude during different stages of the flood. Supported by experimental results, he found that the response of bars crucially depends on the ratio between the flood duration and the bar-growth timescale. Nevertheless, the effect of a complex flow regime, characterised by a sequence of flow events, is to a large extent unexplored. Specifically, (i) the definition of a criterion to predict the average response of alternate bars in a river reach subject to an hydrological flow regime and (ii) the quantification of bar amplitude evolution due to a complex flow regime are still to a large extent unexplored. The goals of this work are: (i) to investigate the dependence of bar properties to variable discharge conditions; (ii) to analyse the effect of flow unsteadiness in terms of duration and sequencing of flood events and derive the main hydrological characteristics that primarily control the average response of bar amplitude; (iii) to determine the long-term bar geometry and define the "bar-forming'' discharge, which is the theoretical discharge that if maintained indefinitely would produce the same long-term bar response as the natural hydrograph; (iv) to analyse the effect that a sequence of flood events composing a complex flow series has on the evolution of bar amplitude. To pursue these purposes, we adopted a methodology primary based on theoretical models, then supported and validated through the analysis of laboratory experiments and field data. The methodology and the key results for the different parts of this thesis can be summarized as follows: 1. First, the response of bar topography to different flow stages has been investigated both theoretically and through the analysis of experimental data, observing the dependence of alternate bars to peculiar threshold conditions. The validity of weakly nonlinear model of Colombini et al. (1987), originally defined in the neighborhood of the critical condition βcr, has been extended taking into account the emersion of bars for low flows. 2. Subsequently, the average response of bars to idealized flow series has been analysed, exploring their dependence on the duration and sequencing of flood events. The probability density function has been found to be the essential hydrological information of the flow series required to determine the long-term response of bar amplitude, while the integral scale of flow sequence is a suitable metric to quantify the unsteadiness of a flow regime. 3. Then, an innovative approach has been introduced to define an occurrence criterion for alternate bars in straightened river reaches that accounts for the hydrological regime, and to determine the average bar state, with the corresponding "bar-forming'' discharge. The key novelty with respect to the classical methods adopted so far to predict the long-term equilibrium channel geometry is that in this case the morphodynamical work acted on river bars by relatively low-flow stages enhancing their formation can be reversed by high-flow stages that suppress them. Therefore, both the occurrence criterion and the average state are found from a balance between the cumulative effects of bar-forming and bar-suppressing events. 4. Finally, the weakly nonlinear model of Colombini et al. (1987), originally defined to predict the evolution of bars under steady flow conditions, has been extended to reproduce a natural flow series by considering the basic flow varying in time. This approach allows us to (i) statistically investigate the effect of flood magnitude and duration on the variations of bar amplitude and (ii) to simulate the morphological response of a river to alterations of the hydrological regime.The long-term analysis of bar amplitude, as such as its evolution subject to the hydrological flow regime, have been applied to four different study cases, each of them characterised by a distinctive average bar response: two reaches of the Alpine Rhine River, upstream and downstream the confluence of the River Ill (Switzerland), respectively, the Adige River near Trento (Italy) and the Isère River near Montmèlian (France). The theoretical model is able to capture both qualitatively and quantitatively the observed bed response. Specifically, it predicts the occurrence of high-relief bars for the upstream reach of the Alpine Rhine River and for the Isère River, while a plane configuration is predicted for the Adige River. Also the intermediate response of the downstream reach of the Alpine Rhine River is reproduced, showing a predominant flat bed morphology with sporadic low-relief bars.
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Carlin, Mattia. „The response of river bar topography to the hydrological flow regime“. Doctoral thesis, Università degli studi di Trento, 2021. http://hdl.handle.net/11572/312573.
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Alternate bars are large-scale bedforms characterised by an ordered sequence of scour zones and depositional diagonal fronts alternating along channel banks, which are typical of straight channelized rivers. Due to their high relief and migration properties, they represent a problem in river management, because they affect navigation, increase the flooding risk and interact with instream structures. For this reason, in the last decades many studies took the challenge of defining suitable criteria able to describe their morphometric properties.
Theoretical, experimental and numerical works have clearly demonstrated that bar occurrence is a threshold process governed by the width-to-depth ratio of the channel, β. If this parameter exceeds a critical threshold, βcr, an instability mechanism amplifies the riverbed perturbations occurring due to the effect of the turbulent flow on the cohesionless riverbed, leading to the spontaneous growth of finite amplitude bars. Under steady flow conditions, alternate bars achieve an equilibrium configuration, whose amplitude value is related to the difference β-βcr.
Much less information is available to describe bar characteristics under variable flow conditions, when the width-to-depth ratio changes in time and the amplitude of bars evolves depending on the duration and the shape of the hydrograph. The effect of a single idealized flood on bar amplitude evolution was successfully described by the weakly nonlinear model of Tubino (1991), which was able to capture the trajectory of bar amplitude during different stages of the flood. Supported by experimental results, he found that the response of bars crucially depends on the ratio between the flood duration and the bar-growth timescale. Nevertheless, the effect of a complex flow regime, characterised by a sequence of flow events, is to a large extent unexplored. Specifically, (i) the definition of a criterion to predict the average response of alternate bars in a river reach subject to an hydrological flow regime and (ii) the quantification of bar amplitude evolution due to a complex flow regime are still to a large extent unexplored.
The goals of this work are: (i) to investigate the dependence of bar properties to variable discharge conditions; (ii) to analyse the effect of flow unsteadiness in terms of duration and sequencing of flood events and derive the main hydrological characteristics that primarily control the average response of bar amplitude; (iii) to determine the long-term bar geometry and define the "bar-forming'' discharge, which is the theoretical discharge that if maintained indefinitely would produce the same long-term bar response as the natural hydrograph; (iv) to analyse the effect that a sequence of flood events composing a complex flow series has on the evolution of bar amplitude.
To pursue these purposes, we adopted a methodology primary based on theoretical models, then supported and validated through the analysis of laboratory experiments and field data. The methodology and the key results for the different parts of this thesis can be summarized as follows:
1. First, the response of bar topography to different flow stages has been investigated both theoretically and through the analysis of experimental data, observing the dependence of alternate bars to peculiar threshold conditions. The validity of weakly nonlinear model of Colombini et al. (1987), originally defined in the neighborhood of the critical condition βcr, has been extended taking into account the emersion of bars for low flows.
2. Subsequently, the average response of bars to idealized flow series has been analysed, exploring their dependence on the duration and sequencing of flood events. The probability density function has been found to be the essential hydrological information of the flow series required to determine the long-term response of bar amplitude, while the integral scale of flow sequence is a suitable metric to quantify the unsteadiness of a flow regime.
3. Then, an innovative approach has been introduced to define an occurrence criterion for alternate bars in straightened river reaches that accounts for the hydrological regime, and to determine the average bar state, with the corresponding "bar-forming'' discharge. The key novelty with respect to the classical methods adopted so far to predict the long-term equilibrium channel geometry is that in this case the morphodynamical work acted on river bars by relatively low-flow stages enhancing their formation can be reversed by high-flow stages that suppress them. Therefore, both the occurrence criterion and the average state are found from a balance between the cumulative effects of bar-forming and bar-suppressing events.
4. Finally, the weakly nonlinear model of Colombini et al. (1987), originally defined to predict the evolution of bars under steady flow conditions, has been extended to reproduce a natural flow series by considering the basic flow varying in time. This approach allows us to (i) statistically investigate the effect of flood magnitude and duration on the variations of bar amplitude and (ii) to simulate the morphological response of a river to alterations of the hydrological regime.
The long-term analysis of bar amplitude, as such as its evolution subject to the hydrological flow regime, have been applied to four different study cases, each of them characterised by a distinctive average bar response: two reaches of the Alpine Rhine River, upstream and downstream the confluence of the River Ill (Switzerland), respectively, the Adige River near Trento (Italy) and the Isère River near Montmèlian (France). The theoretical model is able to capture both qualitatively and quantitatively the observed bed response. Specifically, it predicts the occurrence of high-relief bars for the upstream reach of the Alpine Rhine River and for the Isère River, while a plane configuration is predicted for the Adige River. Also the intermediate response of the downstream reach of the Alpine Rhine River is reproduced, showing a predominant flat bed morphology with sporadic low-relief bars.
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Tse, Kiu-chung. „Estimation of submarine groundwater discharge into Tolo Harbour“. Click to view the E-thesis via HKUTO, 2006. http://sunzi.lib.hku.hk/hkuto/record/B38230926.
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Guinn, Richard J. (Richard Joe). „Biological and Toxicological Responses Resulting from Dechlorination of a Major Municipal Wastewater Treatment Plant Discharge to the Trinity River“. Thesis, University of North Texas, 1995. https://digital.library.unt.edu/ark:/67531/metadc279074/.
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Federal regulations such as the Clean Water Act (P.L. 92-500), and its amendments, direct the Environment Protection Agency (EPA) to implement programs to control the releases of conventional pollutants and toxics into the waterways of the United States. The EPA began requiring treatment plants to conduct toxicity tests (biomonitoring) of their effluent discharges. To control toxicity caused by chlorination of wastewater discharges, the EPA also began requiring some treatment facilities to dechlorinate their wastewater before discharging. This research was funded by the EPA to document the changes that occurred in the Trinity River from the dechlorination of the effluent from Ft. Worth's Village Creek municipal wastewater treatment plant. The study occurred over a two year period beginning in August 1990. A wide variety of biological field assessments and toxicological assays were used to measure various responses. Seven river stations, covering approximately twenty river miles, and the treatment plant effluent were assessed. Two of the river stations were upstream from the treatment plant and used as reference sites. The remaining five river stations were downstream from the treatment plant, spread out over seventeen river miles. The study evaluated the impact of chlorination prior to dechlorination, which served as a baseline. Responses determined during dechlorination were compared to the baseline data. An overall improvement in species richness and diversity was seen at those river stations which had previously been adversely impacted by chlorine. Aquatic toxicity tests, such as those required to be used by dischargers, were conducted during this study. Periodic toxicity was observed with these tests in the effluent and river samples after dechlorination was initiated. Those tests, along with in situ toxicity assays, proved to be good predictors of biological community responses.
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Medupin, Cecilia. „The impact of point source pollution on an urban river, the River Medlock, Greater Manchester“. Thesis, University of Manchester, 2017. https://www.research.manchester.ac.uk/portal/en/theses/the-impact-of-point-source-pollution-on-an-urban-river-the-river-medlock-greater-manchester(3b29a840-ec13-46ee-b436-f9bff37013bb).html.
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The River Medlock is a small (22km) urbanised river, and is one of the five main tributaries which forms part of the River Irwell Catchment in Greater Manchester, UK. The river has a legacy of pollution from the 18th century and continues to be affected by anthropogenic factors including point source pollution from waste water treatment works (WwTWs) and combined sewer overflows (CSOs). In order to investigate the impact of CSOs and the WwTWs on the river hydrology, water quality and ecology of the lower largely urbanised reach, data sets were obtained from the Environment Agency and from direct sampling of the river. Load estimations from continuous discharge records from the river's gauging station plus estimates of sub-catchment area indicate the lower sites, classified as a "highly modified water body" and downstream of treatment works had had a higher load of discharge and phosphate-P linked to point sources and episodic discharges. Short term, continuous monitoring revealed that CSOs were active during high velocity, but increased concentrations of nutrients post high velocity indicate WwTW effects and possibly diffuse sources. This project reveals that the WwTW are a major source of phosphate-P and that the impact of CSOs on the river quality is short-lived and depends on the degree of precipitation. Other parameters indicate good water quality although the benthic macroinvertebrate community is degraded as a result of episodic increases in the quantity of water destabilising the river bed. Therefore, pollution from the CSOs, the WwTW and rapid changes in discharge are the reasons for the river's failure to conform to EU's requirements of the Water Framework Directive.
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Jian, Jun. „Relationship between the Pacific Ocean SST Variability and the Ganges-Brahmaputra River Discharge“. Thesis, Georgia Institute of Technology, 2005. http://hdl.handle.net/1853/6994.
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A simple correlation analysis was used to investigate the linear relationships between sea surface temperature (SST) and monthly flow of Ganges and Brahmaputra at the borders of Bangladesh and India using approximately 50 years of river discharge data. Strong correlations were found between the equatorial Pacific SST and boreal summer Ganges discharge from three-month lag to two-month lead times. The El Nio-Southern Oscillation (ENSO) explains Ganges flow variance exceeding 0.95 significance level using both the Nino 3.4 SST correlation and the composites made for El Nio (La Nina) periods.
The May SST of the southwest Pacific Ocean to the east of Australia continent has a strong correlation (>0.6) with early summer Ganges discharges. Using a lag correlation analysis of Ganges discharge and SST, we found a steady and continuous development in the Nino 3.4 SST relationship, and a strong correlation with the southwest Pacific SST which is most pronounced three-four months prior to the onset of Asian summer monsoon. These relationships mean that at least 25% of the interannual summer Ganges River discharge variability can be explained by antecedent equatorial and southwest Pacific SST. It provides a possible statistical method for linear forecasting two or three months in advance.
The Brahmaputra River discharge, on the other hand, shows weak relationships with tropical SST variability except for the Bay of Bengal and the higher northern latitudes of the Pacific.
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Blair, Timothy. „Stage discharge estimation using a 1d river hydraulic model and spatially-variable roughness“. Thesis, University of British Columbia, 2009. http://hdl.handle.net/2429/17412.
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Stage-discharge relations (rating curves) are integral to stream gauging, yet the existing empirical calibration methods are expensive, particularly in remote areas, and are limited to low flows. Numerical modelling can provide stage-discharge relations from a single site survey, reducing the overall cost, and can be fit to changing surface conditions. This study explores a one-dimensional model to calculate theoretical stage-discharge relations for four field sites in British Columbia that range in bed stability, bed structure, hydrology and sediment supply. However, due to the non-linear relation between flow and roughness we do not assume the conventional reach-averaged roughness and instead employ a spatially-distributed roughness model. Furthermore, based on local grain size distribution and refined field survey technique, new formulae for wetted perimeter, flow area, and flow depth were developed that eliminate commonly held modelling assumptions and reduce topographic error. The results show (1) good agreement with Water Survey of Canada measurements, (2) distributed roughness provided an improvement over spatially-averaged roughness, (3) spatial variability of the geomorphology within the channel reach leads to shifts in the stage-discharge relations and high sediment amplifies those shifts, and (4) the relations must be re-evaluated following events that mobilize the bed. The method can be used to estimate high flows and flows in remote locations and it does not require calibration.
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Chan, Yi-kei, und 陳伊祺. „Nutrient input of Tolo Harbour by river, atmospheric deposition and submarine groundwater discharge“. Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2011. http://hub.hku.hk/bib/B46732718.
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ALONGI, Francesco. „River flow monitoring: LS-PIV technique, an image-based method to assess discharge“. Doctoral thesis, Università degli Studi di Palermo, 2022. https://hdl.handle.net/10447/575301.
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The measurement of the river discharge within a natural ort artificial channel is still one of the most challenging tasks for hydrologists and the scientific community. Although discharge is a physical quantity that theoretically can be measured with very high accuracy, since the volume of water flows in a well-defined domain, there are numerous critical issues in obtaining a reliable value.
Discharge cannot be measured directly, so its value is obtained by coupling a measurement of a quantity related to the volume of flowing water and the area of a channel cross-section. Direct measurements of current velocity are made, traditionally with instruments such as current meters. Although measurements with current meters are sufficiently accurate and even if there are universally recognized standards for the current application of such instruments, they are often unusable under specific flow conditions. In flood conditions, for example, due to the need for personnel to dive into the watercourse, it is impossible to ensure adequate safety conditions to operators for carrying out flow measures.
Critical issue arising from the use of current meters has been partially addressed thanks to technological development and the adoption of acoustic sensors. In particular, with the advent of Acoustic Doppler Current Profilers (ADCPs), flow measurements can take place without personnel having direct contact with the flow, performing measurements either from the bridge or from the banks. This made it possible to extend the available range of discharge measurements.
However, the flood conditions of a watercourse also limit the technology of ADCPs. The introduction of the instrument into the current with high velocities and turbulence would put the instrument itself at serious risk, making it vulnerable and exposed to damage. In the most critical case, the instrument could be torn away by the turbulent current.
On the other hand, considering smaller discharges, both current meters and ADCPs are technologically limited in their measurement as there are no adequate water levels for the use of the devices.
The difficulty in obtaining information on the lowest and highest values of discharge has important implications on how to define the relationships linking flows to water levels. The stage-discharge relationship is one of the tools through which it is possible to monitor the flow in a specific section of a watercourse. Through this curve, a discharge value can be obtained from knowing the water stage. Curves are site-specific and must be continuously updated to account for changes in geometry that the sections for which they are defined may experience over time. They are determined by making simultaneous discharge and stage measurements. Since instruments such as current meters and ADCPs are traditionally used, stage-discharge curves suffer from instrumental limitations. So, rating curves are usually obtained by interpolation of field-measured data and by extrapolate them for the highest and the lowest discharge values, with a consequent reduction in accuracy.
This thesis aims to identify a valid alternative to traditional flow measurements and to show the advantages of using new methods of monitoring to support traditional techniques, or to replace them. Optical techniques represent the best solution for overcoming the difficulties arising from the adoption of a traditional approach to flow measurement. Among these, the most widely used techniques are the Large-Scale Particle Image Velocimetry (LS-PIV) and the Large-Scale Particle Tracking Velocimetry. They are able to estimate the surface velocity fields by processing images representing a moving tracer, suitably dispersed on the liquid surface. By coupling velocity data obtained from optical techniques with geometry of a cross-section, a discharge value can easily be calculated.
In this thesis, the study of the LS-PIV technique was deepened, analysing the performance of the technique, and studying the physical and environmental parameters and factors on which the optical results depend.
As the LS-PIV technique is relatively new, there are no recognized standards available for the proper application of the technique. A preliminary numerical analysis was conducted to identify the factors on which the technique is significantly dependent. The results of these analyses enabled the development of specific guidelines through which the LS-PIV technique could subsequently be applied in open field during flow measurement campaigns in Sicily. In this way it was possible to observe experimentally the criticalities involved in applying the technique on real cases. These measurement campaigns provided the opportunity to carry out analyses on field case studies and structure an automatic procedure for optimising the LS-PIV technique. In all case studies it was possible to observe how the turbulence phenomenon is a worsening factor in the output results of the LS-PIV technique. A final numerical analysis was therefore performed to understand the influence of turbulence factor on the performance of the technique. The results obtained represent an important step for future development of the topic.
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Karki, Nimisha. „ASSESSING THE ROLE OF RIVER TRAINING STRUCTURES – CHEVRON AND DIKE IN THE CREATION AND DIVERSIFICATION OF PHYSICAL AQUATIC HABITATS IN THE MIDDLE MISSISSIPPI RIVER“. OpenSIUC, 2020. https://opensiuc.lib.siu.edu/theses/2739.
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The Mississippi River is one of the most intensively managed and altered river systems in the world. The alterations to the Mississippi have been largely made to meet navigation demands and mitigate floods. River training has been undertaken using rock structures, commonly referred to as river training structures (RTS), to modify the shape of the river to maintain the Congressional mandated navigation channel dimensions. In addition to maintaining the navigation channel, newer RTS such as chevrons, have been claimed to be designed as an improvement to the previously existing dikes. They are considered to be tools of improving riverine habitat by increasing physical habitat heterogeneity within the highly engineered and consequently uniform river channel. Thus, to evaluate the differences in physical habitat heterogeneity created by the two RTS; a dike and a chevron, this study models and compares the physical aquatic habitats created along the Middle Mississippi River near Grand Tower, Illinois. The hydraulic modelling software HEC-RAS has been used to develop a two-dimensional model of the study area containing the RTS using detailed 2 m- resolution topobathy digital elevation model (DEM), U.S Geologic Survey’s National Land Cover Database (NLCD), an existing one-dimensional model of the Mississippi and hydrologic data from several hydrologic monitoring stations for the years 2008-2016. Depth and velocity grids were extracted from the HEC-RAS model for three different discharge conditions; 0.5 mean annual flow (MAF) with 40% exceedance probability, MAF with 80% exceedance probability and 1.5 MAF with 15% exceedance probability were used to develop and categorize physical habitat distribution maps of the study area using ArcGIS. The modeled physical aquatic habitat patches were assessed at three buffer distances of 30 m, 90 m, and 150 m from the RTS. The area Simpson diversity and Jaccard similarity indices were calculated for the different discharge conditions and associated habitat mosaics. The distribution of physical habitat modeling revealed a variation in the pattern of habitat patches between the dike and chevron. For the chevron dike evaluated in this study, very-slow deep habitat patches are created in the inner portion of the chevron and slow deep patches around the exterior of the structure which extend both up and downstream of the structure. The dike created slow-deep habitat patches along the structure, very-slow deep patches on the riverbank edge and fast- deep patches on the river side edge. Evaluation of physical habitat patch diversity in relation to the distance from the RTS revealed the highest diversity index values were found within the first 30 m buffer and generally decrease with distance away from the structure. Comparison of the Jaccard index values in vicinity of the two evaluated RTS suggest the habitat patch diversity are similar for both structures at 0.5 MAF and 1.5 MAF flow conditions (index value ranging between 0.60-0.87). However, for the MAF flow conditions the Jaccard index suggests there is more physical habitat patch diversity in the vicinity of the chevron relative to the dike. The modeling results suggest both physical habitat patch richness and diversity declines with an increase in discharge. The decline in physical habitat patch richness and diversity with discharge conditions were greater for the dike relative to the chevron, thus while the chevron retains more types of habitat patches with increase in discharge the diversity indices are still higher for the dike. The modeling also suggests both RTS have created and maintain shallow water habitat (SHW) and overwintering habitat patches (OWH) for the flow conditions evaluated in this study. These habitat patches are utilized by fish species at various life stages. Larger area of OWH habitats; 30% of total area by dikes and 35% of total area by chevrons are created in comparison to SWH; 10% by dike and 7% by chevron. The modeling results show that both the dike and chevron evaluated in this study are associated with and likely maintain ecologically relevant habitats and substantially contribute to physical habitat diversity. If the physical characteristics of the RTS investigated here are similar to other dikes and chevrons along the Mississippi River, the results of this study supports the secondary management objective for these structures, increase in physical aquatic habitat patch diversity, is likely being achieved.
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Al-Mefleh, Naji K. „Impact of land cover and antecedent moisture content on runoff discharge in the West Fork of the upper White River, Indiana“. Virtual Press, 2003. http://liblink.bsu.edu/uhtbin/catkey/1285410.
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Tegegn, Ferezer. „Can precipitation change explain the increased in discharge from the Blue Nile River Basin?“ Thesis, Stockholms universitet, Institutionen för naturgeografi och kvartärgeologi (INK), 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-43298.
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A large amount of Nile water originates in Ethiopia. However, large uncertainty arises concerning whether land degradation or climate change is the cause for the observed increase in discharge along downstream countries. Previous studies showed increases in discharge at Kessie, Bahir Dar and El Diem over the past four decades with no increase in basin-average rainfall. They cite changes in landscapes or soil coverage as a potential reason for this change. However, the study in this thesis shows that the change in discharge could also be explained in part by spatial changes in precipitation. This thesis investigates trends in rainfall within the Blue Nile River Basin f rom 1963 to 2003. For this study total monthly and daily precipitation data were collected from across the Blue Nile River Basin and analyzed statistically. The results indicate spatial variability in the rainfall observed. The general long-term trends in annual as well as in seasonal precipitation show a general decreasing trend along southwest regions of the study area. However, an increasing trend was encountered along northeast and southeast region of the Basin (3 of 9 selected stations). Rainfall-runoff modelling was performed to estimate the required precipitation increase to produce the increase in discharge observed in the Blue Nile River Basin. Precipitation needed to increase between 10 % and 25 % to account for the increased discharge. This increase is similar to that observed for some of the precipitation stations showing that increase in discharge seen in the Blue Nile River Basin may in part be due to changes in precipitation.
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Toan, Duong Duc. „Assessment of river discharge changes in the Indochina Peninsula region under a changing climate“. 京都大学 (Kyoto University), 2015. http://hdl.handle.net/2433/195976.
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Crisp, Annesley. „Analysing stormwater temperature at site-specific discharge points along the Liesbeek River, South Africa“. Master's thesis, University of Cape Town, 2016. http://hdl.handle.net/11427/22883.
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Increased urban development has resulted in increased impervious landcover and the removal of natural vegetation. The continued anthropic modification of the Earth's surface towards an urban state, has had profound effects on the surrounding natural systems (Thompson et al., 2008). Consequently, recent studies have highlighted a strong link between expanding urbanisation and thermal impacts on streams and rivers draining urban catchments (Roa-Espinosa et al., 2003; Arrington, 2003; Herb et al., 2009b). Anthropogenic perturbations such as thermal pollution can adversely disturb the natural thermal regime of a river (Boothe and Bledsoe, 2009). An important source of thermal pollution is thermally enriched stormwater runoff. During a rainfall event, runoff temperature is elevated as it makes contact with, and passes over surfaces which have a large heat storage capacity, such as pavements, roofs and roads (Young et al., 2013). However, the extent of impervious surfaces and resulting thermal pollution produced by them is poorly understood, although it is thought to be a major contributor to stream degradation. Previous research has focused on investigating the thermal effects of removing riparian vegetation. Additionally, a recent research approach has been to develop models of the urban surface-water-atmosphere systems. Finally, research in the field of fresh-water ecology has investigated the effects of temperature on aquatic biota. Water temperature affects all aspects of freshwater ecosystems and plays an important role in regulating physical and biological characteristics of a river (Olsen et al. 2011). Consequently, any anthropogenic modification to temperature can have devastating effects on the ecological functioning of a river and biodiversity of species within the river habitat. Important findings by Young et al. (2013) suggest the need for a detailed study of stormwater temperature changes in relation to rainfall events, at a catchment scale. Furthermore, data is required to show the point source effects of stormwater runoff from impervious surfaces on the temperature of the receiving water body. Therefore, the aim of this study is: To determine the extent and risk of thermal pollution at site specific discharge points, along the Liesbeek River. In order to achieve this aim, variables which cause temperature variations needed to be identified. The primary research method makes use of Thermocron iButton Temperature Loggers. These were placed in four stormwater outlet pipes, which frequently discharge event-based stormwater runoff into the Liesbeek River. Additionally, iButton loggers were placed in the river channel, to provide a reference temperature to compare stormwater discharge temperature. In addition, hourly rainfall and air temperature was acquired from the South AfricanWeather Service (SAWS) and was used in conjunction with the iButton temperature data.
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Prohaska, Paul D. „Investigation of the discharge coefficient for circular orifices in riser pipes“. Connect to this title online, 2008. http://etd.lib.clemson.edu/documents/1219852241/.
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