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1
Tolouie, Esmaiel. "Reservoir sedimentation and de-siltation." Thesis, University of Birmingham, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.551025.
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An attempt has been made to review and summarize available knowledge pertaining to sedimentation and de-siltation of storage reservoirs. Additional data have been collected on Sefid - Rud Reservoir (Iran), during its normal and de-siltation operation periods. Some supplementary measures have been introduced to increase the de-siltation efficiency of flushing operations, based on field observations and experiments made during de- iltation operation of Sefid - Rud Reservoir. These measures seem to be a practical and cheap tools for conservation and rehabilitation of large - capacity reservoirs. It is hoped that the subject of resevoir sedimentation may be advanced as much as its importance warrants.
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Velasco, Victor V. "Evaluation and cost comparison of anti-siltation systems and traditional dredging methods." Springfield, Va. : Available from National Technical Information Service, 2000. http://handle.dtic.mil/100.2/ADA387800.
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White, James. "The use of sediment traps to monitor marina siltation with particular reference to Port Hamble Marina." Thesis, University of Southampton, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.277497.
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Soetanto, Budi, and soetanto@gmail com. "EVALUATION OF SEDIMENTATION PROCESSES IN A COASTAL LAKE: CAUSEWAY LAKE, THE CAPRICORN COAST CASE STUDY." Central Queensland University. Engineering, 2007. http://library-resources.cqu.edu.au./thesis/adt-QCQU/public/adt-QCQU20070622.122252.
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This thesis presents analysis of the hydrodynamic and sedimentation changes of the Causeway Lake, Queensland. It was created in 1939 when a causeway and bridge construction was built across the estuary entrance. Since the construction, significant sediment retention has occurred in the lake. The sediment study presented in this thesis was undertaken based on historical data, field data measurement and numerical modelling, supported by theoretical analysis.
Based on bathymetry data for the period from 1986 and 2003, an average of 2500 m3/year of sediment has settled in the estuary. To verify the sources of sedimentation, field measurements were undertaken at selected sections at two upstream boundaries (Mulambin and Shoal Creeks), and at the downstream boundary under the bridge.
Four sets of field measurements with tidal elevation up to 4.5 m (0.8 m above the bridge sill) were analysed. Results showed that sediment transport in from the sea side was about 1050 m3/year and from the catchments area was in the order of 1100 m3/year (wash load was not included).
Implementation of numerical modelling using RMA required calibration using field data. The predicted sediment transport was in order of 2900 m3/year. The calibrated model was used to simulate the sedimentation pattern for the next 10 years. Four scenarios were analysed, and the resulting recommendation was to dredge out about 141,000 m3 sediment from the Mulambin Creek branch area. Other solutions were also suggested: improvement of lake management and possibility to raise the sill level (water gate).
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Camargo, André Aukar Britschgy de. "Avaliação e quantificação da contribuição de uma voçoroca para o assoreamento do Ribeirão das Cruzes, tributário da represa de Três Irmãos, SP." Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/18/18139/tde-10092012-110206/.
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Devido a dificuldade em se modelar a contribuição de aporte de sedimentos provenientes de erosões lineares em uma bacia hidrográfica, muitas vezes estes são desconsiderados nos estudos hidrossedimentológicos, contudo, podem corresponder a parcela significativa do assoreamento. O presente projeto analisou como a contribuição de uma voçoroca no município de Santo Antônio do Aracanguá (SP), para o assoreamento do Ribeirão das Cruzes, tributário do reservatório da UHE Três Irmãos (Rio Tietê). O estudo foi conduzido por meio de pesquisa teórica (levantamento bibliográfico), coletas de dados na área de estudo e por meio de simulação computacional. Com auxílio de ferramentas de geoprocessamento foram quantificados o volume assoreado no tributário determinado por levantamento batimétrico (12,31 hm³) e o volume de solo erodido na voçoroca por meio de levantamento topográfico (0,22 hm³). Comparando estes resultados obtivemos a contribuição de 1,80% da erosão linear para o assoreamento do tributário nos 21,12 anos anteriores a pesquisa. No entanto, devido a estimativa do surgimento e desenvolvimento da voçoroca estar associado aos últimos 7,11 anos, a contribuição no assoreamento para este período foi de 5,17%. O estudo ainda apontou o depósito destes sedimentos nos primeiros 2 km à jusante da interface erosão-represa. Erosões lineares podem contribuir significativamente no processo de assoreamento como demonstrado no estudo de caso, sendo necessário se considerar este tipo de contribuição nos estudos de aporte de sedimento em corpos d\'água.Due the difficulty of modeling the contribution of sediment delivery from linear erosions in a watershed, these are often overlooked in hydrosedimentological studies, however, may represent a significant portion of siltation. This project analyzes the contribution of a gully erosion in Santo Antonio do Aracanguá (SP) for the sedimentation of Ribeirão das Cruzes, a tributary of the UHE Three Brothers reservoir (Tietê River). The study was conducted from theoretical research (bibliographic research), data collection in the study area and through computer simulation. With the aid of GIS tools were quantified the silted volume in the tributary, determined by bathymetric survey (12.31 hm³) and the volume of eroded soil in the gully erosion by topography surveying (0.22 hm³). Comparing these results, we have obtained the contribution of 1.80% from linear erosion to the sedimentation in the tributary during the 21.12 years preceding the survey. However, due to estimative of the beginning and development of the gully erosion being associated with the last 7.11 years, the contribution to sedimentation in this period was 5.17%. The study also accused the deposit of sediment in the first 2 km downstream interface \"erosion-dam\". Linear erosions can contribute significantly in the process of sedimentation as shown in the study case, being necessary to consider this type of contribution in studies of sediment input into water bodies.
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Thompson, Adam. "Walleye Habitat Use, Spawning Behavior, and Egg Deposition in Sandusky Bay, Lake Erie." The Ohio State University, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=osu1253639267.
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Colagiovanni, Alessandro. "Assessment of the resilience of coral reefs to natural and human disturbances by means of recruitment panels in Indo-Pacific." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2016. http://amslaurea.unibo.it/9767/.
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Indo-Pacific region encompasses about 75% of world's coral reefs, but hard coral cover in this region experienced a 32% region-wide decline since 1970s. This great change is primarily ascribable to natural and anthropogenic pressures, including climate change and human activities effects. Coral reef conservation requires management strategies oriented to maintain their diversity and the capacity to provide ecosystem goods and services. Coral reef resilience, i.e. the capacity to recover after disturbances, is critical to their long-term persistence. The aims of the present study were to design and to test field experiments intended to measure changes in recruitment processes, as a fundamental aspect of the coral reef resilience. Recruitment experiments, using artificial panels suspended in the water column, were carried out in two Indo-Pacific locations affected by different disturbances: a new mine in Bangka Island (Indonesia), and the increased sedimentation due to coastal dynamics in Vavvaru Island (Maldives). One (or more) putatively disturbed site(s) was selected to be tested against 3 randomly selected control sites. Panels’ arrangement simulates 2 proximities to living corals, i.e. the sources of propagules: few centimetres and 2 meters over. Panels were deployed simultaneously at each site and left submerged for about five months. Recruits were identified to the lowest possible taxonomic level and recruited assemblages were analysed in terms of percent cover. In general it was not possible to detect significant differences between the benthic assemblages recruited in disturbed and control sites. The high variability observed in recruits assemblages structure among control sites may be so large to mask the possible disturbance effects. Only few taxa showed possible effects of the disturb they undergo. The field tests have highlighted strengths and weaknesses of the proposed approach and, based on these results, some possible improvements were suggested.
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Wermuth, James A. "DETERMINING FACTORS THAT CONTRIBUTE TO NONPOINT SOURCE POLLUTION IN THE LOWER KENTUCKY WATERSHED." UKnowledge, 2007. http://uknowledge.uky.edu/gradschool_theses/440.
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The water quality in the United States has greatly improved since the implementation of the Clean Water Act (CWA) in the early 1970s. Unfortunately, the Clean Water Act only addresses one kind of water pollution, point source pollution. The major problem that is present in the degradation of todays water quality has to deal with nonpoint source pollution. Agriculture is commonly regarded as the leading contributor to nonpoint source pollution in the United States. This study uses two analytical tools to try to determine the significant factors in the transport of pollutants in the Lower Kentucky Watershed, located in central Kentucky. Spatial analysis (GIS) coupled with the statistical analysis (SAS), allowed for significant factors to be identified within a small proximity of sampling sites throughout the watershed. The results suggest that although agriculture is commonly regarded as the largest contributor to nonpoint source pollution, other factors outside of agriculture were also found to be significant, such as resident land use and rainfall. The results generated from this study suggest that land managers in communities throughout the watershed should analyze agricultural factors, as well as, factors outside of agriculture, in an effort to protect their communities water quality.
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Brito, Geanne Moreira. "Determinação do assoreamento do reservatório da PCH Cachoeirão." Universidade Federal de Viçosa, 2013. http://locus.ufv.br/handle/123456789/3813.
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All reservoirs formed by dams are subject to the process of sedimentation. Sediment accumulation reduces reservoir s useful volume and causes modifications in its elevation x area x volume (EAV) curves, which must be periodically updated. In this context, this study aims to evaluate the siltation process in SHP (Small Hydropower Plant) Cachoeirão reservoir and to update its operational data. The methodology consisted of comparing the results obtained before and after the reservoir filling, using Digital Elevation Model (DEM) and the fuction TIN (Triangulated irregular network), allowing to generate the EAV curves and to identify the total volumes of sediment deposited in the reservoir and the sediment level in the water intake. From this comparison, it was determined that, during 13 years of operation, the volume of sediment deposited on Cachoeirão s lake was equal to 0.866 hm3. This value represents a reduction of 15.9% in the original storage capacity of the reservoir. The softwares Sediment and Dposit were also used to assess the siltation process in SHP Cachoeirão and their results indicated an underestimation of the deposited sediments volume, in comparison to field results. The sediments accumulated at the bottom of the reservoir presented a variable grain size distribution, ranging from sand size observed in particles deposited closer to the start of backwater, until clay size, observed in particles deposited near to the dam axis. The study also concluded that the expected useful lifetime of the reservoir should not be achieved, unless preventive measures are taken to reduce the amount of sediment that enters the reservoir.
Reservatórios formados por barragens estão sujeitos ao processo de assoreamento. O acúmulo de sedimentos reduz o volume útil do reservatório e provoca alterações em suas curvas cota x área x volume (CAV), que devem ser atualizadas periodicamente. Nesse contexto, este estudo objetivou avaliar o processo de assoreamento no reservatório da PCH Cachoeirão e atualizar os seus dados operacionais. A metodologia empregada consistiu na comparação dos resultados obtidos antes e depois do enchimento do reservatório, com a utilização de Modelo Digital de Elevação (MDE) e função TIN (Triangulated irregular network), que possibilitou gerar as CAV, e identificar volumes de sedimentos totais e níveis de sedimentos na tomada d ́água. A partir dessa comparação, determinou-se que em 13 anos de operação o volume de sedimento depositado no lago da PCH Cachoeirão foi de 0,866 hm3. Esse valor representa uma redução de 15,9% na capacidade de armazenamento original do reservatório. Os softwares Sediment e Dposit também foram utilizados para avaliar o assoreamento da PCH Cachoeirão e seus resultados indicaram uma subestimativa do volume de sedimentos depositado, em relação aos resultados observados em campo. Os sedimentos acumulados no fundo do reservatório apresentaram distribuição granulométrica variável, desde partículas na fração areia, depositadas próximas ao início do remanso, até partículas na fração argila, depositadas próximas ao eixo da barragem. O estudo permitiu concluir que a vida útil esperada para o reservatório não deverá ser alcançada se medidas preventivas, que reduzam a quantidade de sedimentos que adentra o reservatório, não forem tomadas.
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Cetinkaya, Oguz Kagan. "Management Of Reservoir Sedimentation Case Studies From Turkey." Master's thesis, METU, 2006. http://etd.lib.metu.edu.tr/upload/12607016/index.pdf.
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Siltation is becoming a big problem as the dams get older all over the world. Conservation and sustainable management of existing reservoirs is gaining more importance than constructing new dams. In this study the program RESCON, which is outcome of a World Bank sponsored project, has been used to examine sediment removal strategies (flushing, hydrosuction sediment removal, dredging and trucking) for four dams of Turkey namely Çubuk I Dam, Bayindir Dam, ivriz Dam and Borç
ka Dam. Sediment measurements are made by governmental agencies in Turkey. In this study characteristics of these measurements will be presented for the future sediment related studies. Then sediment removal strategies which were used in RESCON will be introduced. Evaluation of RESCON results have been made and compared with previous studies for verification except Borç
ka Dam, since it is under construction.
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Costa, Ivo Gilberto Duarte David da. "Análise do assoreamento no reservatório de Três Irmãos - SP, utilizando dados topobatimétricos, hidrológicos e técnicas de geoprocessamento." Universidade de São Paulo, 2009. http://www.teses.usp.br/teses/disponiveis/18/18139/tde-29092009-113504/.
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O processo de sedimentação em reservatórios gera várias conseqüências, dentre elas, o impacto acumulativo da perda de capacidade de armazenamento destes. Este fato faz com que, dependendo dos usos, eles percam a sua funcionalidade tal como a capacidade de regularização de vazão. Tais efeitos não afetam somente uma única atividade econômica que venha a existir nesses reservatórios. Grande parte do modelo econômico que é sustentado pelos usos nestes é afetado. A sedimentação é um processo que não se consegue resolver totalmente, cabendo somente a utilização de técnicas adequadas de manejo da bacia de contribuição do reservatório, reduzindo assim o assoreamento. A presente pesquisa teve como base informações coletadas no reservatório da UHE de Três Irmãos SP, sendo tais informações provenientes de cartas topográficas, estações de monitoramento de chuva, imagens de satélites e campanhas de batimetria no reservatório em estudo. Assim obteve-se que o reservatório está com aproximadamente 6,73% do seu volume assoreado, com uma taxa anual media de assoreamento de 0,4%, se mantendo abaixo da média brasileira e mundial, que é de respectivamente de 0,5% e 1%.The sedimentation process in reservoirs brings some consequences, among them, the cumulative impact on lacking of the storage capacity of those reservoirs. Depending on the uses of those reservoirs, they may lose their capability of flow regularization. Such effects not only affect one kind of economical activity that may exist upon these reservoirs. A considerable part of the economical model that is supported by those uses is also affected. The sedimentation is a process that can\'t be completely solved, unless the correct use of suitable techniques of management of the contribution basin of the reservoir can reduce the siltation. This research has its foundation on the collected information on the Três Irmãos hydroelectric power plant reservoir, consisting of topographic maps, rain monitoring checkpoints, satellite images and bathymetri campaigns on that reservoir. Thus, it was concluded that the reservoir has approximately 6,73% of its volume silted, and also has a annual average rate of siltation of 0,4%, below the brazilian and world average, 0,5% and 1%, respectively.
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Reinwarth, Bastian [Verfasser], Jussi [Gutachter] Baade, Roland [Gutachter] Mäusbacher, and Hans-Rudolf [Gutachter] Bork. "Contemporary erosion rates in the Kruger National Park, South Africa, inferred from reservoir siltation surveys / Bastian Reinwarth ; Gutachter: Jussi Baade, Roland Mäusbacher, Hans-Rudolf Bork." Jena : Friedrich-Schiller-Universität Jena, 2020. http://d-nb.info/121521006X/34.
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Oliveira, Ana Cristina Bastos de. "AvaliaÃÃo da qualidade das Ãguas do aÃude Santo AnastÃcio." Universidade Federal do CearÃ, 2013. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=9997.
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nÃo hÃO Brasil possui um grande volume de Ãgua doce, porÃm a RegiÃo Nordeste e o Estado do Cearà sofrem pela escassez deste recurso. Diante deste quadro muitos rios desta regiÃo foram barrados para a construÃÃo de reservatÃrios. Inserido neste contexto està o aÃude Santo AnastÃcio (ASA), objeto desta pesquisa, localizado em Fortaleza-CearÃ. O ASA està sofrendo progressivo processo de perda da qualidade e da profundidade de suas Ãguas, principalmente em funÃÃo das aÃÃes antrÃpicas. Assim, esse trabalho teve como objetivo diagnosticar a evoluÃÃo da perda dessa qualidade, por meio de anÃlises fÃsicas, quÃmicas e biolÃgicas, alÃm de calcular o Ãndice de qualidade das Ãguas (IQA) do aÃude, avaliar o nÃvel de eutrofizaÃÃo e de assoreamento e estudar a variabilidade espacial e temporal dos seus parÃmetros limnolÃgicos. Todos os mÃtodos de anÃlise utilizados foram baseados na 21 ediÃÃo do âStandard methods for the examination of water and waterwaste â APHA-AWWA-WPCFâ. De acordo com os resultados, pode-se concluir que alguns dos parÃmetros analisados, entre eles OD, fÃsforo total e DBO, estÃo em desacordo com os padrÃes estabelecidos para Ãgua doce, classe 3, pela ResoluÃÃo CONAMA n 357, na qual o ASA foi classificado, de acordo com seus usos preponderantes. Isto significa que esse corpo dâÃgua se encontra imprÃprio para as finalidades para as quais ele se destina atualmente. A avaliaÃÃo desse corpo hÃdrico apontou para baixa qualidade das suas Ãguas, segundo o cÃlculo do IQA, que oscila entre bom e ruim, com agravamento na qualidade no ponto 1, que à a regiÃo do aÃude prÃxima à comunidade que reside no seu entorno. Com relaÃÃo ao seu nÃvel de eutrofizaÃÃo, ele foi classificado como hipereutrÃfico, classificaÃÃo mais elevada no processo de envelhecimento artificial. Quanto à variaÃÃo temporal dos parÃmetros analisados, pode-se concluir que houve sazonalidade, com influÃncia do clima local. Esse fato foi observado por meio do estudo das correlaÃÃes entre os fatores climÃticos no teste de Tukey e ratificado pela anÃlise de componentes principais (PCA). Com relaÃÃo à variaÃÃo espacial, ela nÃo foi observada na maioria das variÃveis, com exceÃÃo do OD, que mostrou heterogeneidade no ponto 1, de acordo com o teste de Tukey.
Brazil has a large quantity of freshwater, but the Northeast Region and state of Cearà suffer scarcity of this resource. In function of this, many rivers were barred to build reservoirs. Within this context, there is the Santo AnastÃcio dam (ASA), the object of this research, located in Fortaleza-CearÃ. ASA is suffering progressive losses in the quality and depth of waters, mainly due to human actions. Thus, this study aimed to diagnose the evolution of this degradation by physical, chemical and biological analysis, as well as to calculate the water quality index (IQA) for ASA, to evaluate eutrophication and siltation levels and to study the spatial and temporal variability of their limnological parameters. All methods used here were based on the 21st edition of Standard methods for the examination of water and waterwaste - APHA-AWWA-WPCF. By the results, it was possible to conclude that some of the analysed parameters, including OD, total phosphorus and BOD, were evaluated against the established standards for freshwater, class 3, by âResoluÃÃo CONAMA nÂ357â, in which ASA was classified according to its predominant uses. This means that this reservoir is unfit for the purposes for which it is currently used. The results indicated a low quality of the waters, according to IQA, which oscillated between good and bad, with deterioration in quality, at the point 1, which is the region of ASA dam near the community that resides in its surroundings. About the level of eutrophication, it was classified as hypertrophic, higher ranking in artificial aging process. Regarding the temporal variation of the parameters, it can be concluded that there was seasonal, with the influence of local climate. This fact was observed by the study of correlations among the climatic factors using Tukeyâs test and ratified by Principal Component Analysis (PCA). In relation to spatial variation, it was not observed in most variables, except the OD, that exhibited heterogeneity at the point 1, according to Tukeyâs test.
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Lopes, Josà Wellington Batista. "Hydrossedimentological modeling in semiarid meso-basin." Universidade Federal do CearÃ, 2013. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=10890.
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FundaÃÃo Cearense de Apoio ao Desenvolvimento Cientifico e TecnolÃgicoPractical problems related to water resources and the need for resolution of these was what drove the hydrological modeling, since understanding of the hydrological behavior of the basin was needed. So, this research was conducted to assess, through hydrossedimentological modeling, the behavior of a semiarid meso scale watershed as well as its water availability. The study area was the Madalena Representative Basin, Federal State of CearÃ, with 124kmÂ. Rainfall, accumulated volume and sedimentation in two reservoirs were monitored. The WASA-SED (Model of Water Availability in Semi-Arid Environments Sediment Dynamics with Component) and VYELAS (Volume-Yield Elasticity) models were used in the evaluation. Some conclusions could be obtained from the results: i) Continuous monitoring of hydrological variables in watersheds of the Brazilian semiarid is necessary because the scarcity of data makes it difficult to analyze the performance of hydrological models, ii) Sedimentation measurements in reservoirs is essential for validating of sedimentological routines of model for evaluation of long periods, iii) The soil parameters are determinant in the quality of the results and details of the parameterization significantly improves the performance of the WASA model, iv) The predominance of drought scenario for the next years must affect water supply due to the low volume currently accumulated in the reservoir, v) Water availability of the strategic reservoir of the basin (Marengo reservoir) in extreme years of low rainfall, for 90% reliability yield,is 96% lower than the availability expected for regular years.
Problemas prÃticos relacionados aos recursos hÃdricos e a necessidade de resoluÃÃo desses foi o que impulsionou a modelagem hidrolÃgica, pois uma melhor compreensÃo do comportamento hidrolÃgico da bacia hidrogrÃfica se fez necessÃria. Assim esta pesquisa foi conduzida com o objetivo de avaliar, por meio da modelagem hidrossedimentolÃgica, o comportamento de uma bacia hidrogrÃfica de meso-escala no semiÃrido, assim como sua disponibilidade hÃdrica. A Ãrea foco do estudo foi a Bacia Representativa de Madalena, CearÃ, com 124kmÂ. Os modelos WASA-SED (Model of Water Availability in Semi-Arid Environments with Sediment Dynamics Component) e VYELAS (Volume-Yield Elasticity) foram utilizados na avaliaÃÃo. Algumas conclusÃes puderam ser constatadas a partir dos resultados obtidos: i) O monitoramento contÃnuo das variÃveis hidrolÃgicas em bacias hidrogrÃficas do semiÃrido se faz necessÃrio, pois a insuficiÃncia de dados dificulta a anÃlise do desempenho de modelos hidrolÃgicos; ii) A quantificaÃÃo do assoreamento em reservatÃrios à essencial para a validaÃÃo de rotinas sedimentolÃgicas do modelo para longos perÃodos de avaliaÃÃo; iii) Os parÃmetros do solo sÃo determinantes na qualidade dos resultados e o detalhamento da parametrizaÃÃo melhora sensivelmente o desempenho do modelo WASA; iv) O predomÃnio do cenÃrio de estiagem para os prÃximos anos compromete o abastecimento devido ao baixo volume acumulado atualmente no reservatÃrio; v) A disponibilidade hÃdrica do reservatÃrio estratÃgico da bacia (Marengo) em anos extremos de baixa pluviometria, para uma vazÃo com 90% de garantia, à 96% inferior à disponibilidade para os anos mÃdios.
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Aras, Tuce. "Cost Anaysis Of Sediment Removal Techniques From Reservoir." Master's thesis, METU, 2009. http://etd.lib.metu.edu.tr/upload/12610585/index.pdf.
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Siltation in reservoirs is becoming an important problem as the dams are
getting older in the world. The general dam practice has been implemented in
a sequence thatplanning, design, construction, operation of dam until the accumulated sediment prevents its purpose function or functions. Unfortunately, effects of sedimentation and fate of the left over dams in the future are not figured. Indeed, these negative effects could be avoided, life of the reservoir can be prolonged and even the reservoir will last forever by minimizing the sedimentation. Therefore in this study, the methods that provide extension of reservoir life are discussed hydraulically, economically and applicability point of view. In addition, there is open source package program RESCON which examines and compares some sediment removal techniques economically and also hydraulically. RESCON is used in conjunction with several cases
namely Ç
ubuk Dam-I, Borç
ka Dam and Muratli Dam. Moreover, some sensitivity analyses are carried out in order to scrutiny of the program for Turkish economic conditions.
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Teixeira, Josà JoÃo Lopes. "Hidrossedimentologia e disponibilidade hÃdrica da bacia hidrogrÃfica da Barragem de PoilÃo, Cabo Verde." Universidade Federal do CearÃ, 2011. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=6385.
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Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgicoO ArquipÃlago de Cabo Verde, situado na costa ocidental africana, sofre influÃncia do deserto de Saara tornando o clima caracterizado por pluviometria muito baixa e distribuÃda irregularmente no espaÃo e no tempo. As chuvas sÃo muito concentradas, gerando grandes escoamentos para o mar. O aumento da disponibilidade hÃdrica requer alÃm da construÃÃo e manutenÃÃo de infraestrutura de captaÃÃo e conservaÃÃo de Ãguas pluviais, uma gestÃo eficiente destes recursos. Atualmente, constitui um dos eixos estratÃgicos da polÃtica do Estado de Cabo Verde, a captaÃÃo, o armazenamento e a mobilizaÃÃo de Ãguas superficiais atravÃs de construÃÃo de barragens. Estudos do comportamento hidrolÃgico e sedimentolÃgico do reservatÃrio e da sua bacia de contribuiÃÃo constituem premissas bÃsicas para adequados dimensionamento, gestÃo e monitoramento da referida infraestrutura. à nesse sentido que o presente estudo objetivou sistematizar informaÃÃes hidrolÃgicas e sedimentolÃgicas da bacia hidrogrÃfica da Barragem de PoilÃo (BP) e apresentou proposta operacional de longo prazo. A Ãrea de estudo ocupa 28 km da Bacia HidrogrÃfica da Ribeira Seca (BHRS) na Ilha de Santiago. A altitude da bacia varia de 99 m, situada na cota da barragem, atà 1394 m. Para o estudo, foram utilizados e sistematizados sÃrie pluviomÃtrica de 1973 a 2010, registros de vazÃo instantÃnea do perÃodo 1984 a 2000 e registros agroclimÃticos da Ãrea de estudo de 1981 a 2004. Para o preenchimento das falhas tanto dos escoamentos como da descarga sÃlida em suspensÃo, foi utilizado o mÃtodo de curva chave. Para estimativa de produÃÃo de sedimentos na bacia, aplicou-se a EquaÃÃo Universal de Perda de Solo (USLE) associada à razÃo de aporte de sedimentos (SDR). O Ãndice de retenÃÃo de sedimentos no reservatÃrio foi estimado pelo mÃtodo de Brune e a distribuiÃÃo de sedimento pelo mÃtodo empÃrico de reduÃÃo de Ãrea descrito por Borland e Miller e revisado por Lara. Para gerar e simular curvas de vazÃo versus garantia foi utilizado cÃdigo computacional VYELAS, desenvolvido por AraÃjo e baseado na abordagem de Campos. TambÃm foi avaliada uma possÃvel reduÃÃo da vazÃo de retirada do perÃodo 2006 a 2026, provocada pelo assoreamento do reservatÃrio. Concluiu-se que, em mÃdia, a precipitaÃÃo anual à de 323 mm, concentrando-se 73% nos meses de agosto e setembro; a bacia de contribuiÃÃo apresenta nÃmero de curva (CN) 76, com abstraÃÃo inicial (Ia) de 26 mm, coeficiente de escoamento de 19% e vazÃo anual afluente de 1,7 hm (Cv = 0,73); a disponibilidade hÃdrica para garantia de 85% à 0,548 hmÂ/ano e nÃo 0,671 hmÂ/ano, como indica o projeto original da barragem. Com uma descarga sÃlida avaliada em 22.185 mÂ/ano, estima-se que, atà o ano de 2026, a capacidade do reservatÃrio seja reduzida a uma taxa de 1,8 % ao ano, devido ao assoreamento, provocando uma reduÃÃo de 41% da disponibilidade hÃdrica inicial. Em 2026, segundo as estimativas dessa pesquisa, as perdas por evaporaÃÃo e sangria deverÃo ser da ordem de 81% da vazÃo afluente ao reservatÃrio. Na base desses resultados se apresentou proposta de operaÃÃo da Barragem de PoilÃo
Cape Verde Islands, located in the West African coast, are influenced by the Sahara desert, making the climate characterized by very low rainfall and great spatial and temporal variability. The rainfall events are highly concentrated generating large flows to the sea. The increase of water availability requires construction and maintenance of infrastructure to capture and conserve rainwater, and also an efficient management of these resources. Nowadays, capture, storage and mobilization of water surface through construction of dams is one of the strategic priorities of the policy of the State of Cape Verde. Studies of hydrology and sedimentology of the only existing reservoir (PoilÃo Dam, 1.2 hmÂ) and its watershed are the basic requirements for adequate design, management and monitoring of this infrastructure. In this sense, the present study aimed at systematizing hydrological and sediment information of the PoilÃo Dam and providing a long-term operational proposal. The altitude of the basin varies from 99 m, situated on the dam, up to 1394m. For the study, the following data were used and systematized: rainfall dataset from 1973 to 2010; records of instantaneous flow for the period of 1984 to 2000; and agro-climatic records from 1981 to 2004. To fill the gaps of both flow and suspended-sediment discharge, the rating-curve method was used. To estimate sediment yield in the watershed it was applied the Universal Soil Loss Equation (USLE), associated with the Sediment Delivery Ratio (SDR). The sediment release efficiency rate of the reservoir was estimated by Brune method and the sediment distribution inside the reservoir by the empirical area reduction method described by Borland and Miller, and reviewed by Lara. To assess water availability, water yield versus reliability curves were used. These curves were obtained by the computer code VYELAS, developed by AraÃjo and based on Campos approach. The reduction of the water yield (caused by the reservoir silting) within the period from 2006 to 2026 was also assessed. It was concluded that the average annual rainfall in the watershed is 323 mm, concentrating 73% in August and September; the watershed presents a number of curve (CN) of 76 with an initial abstraction (Ia) of 26 mm, the runoff coefficient is 19% and the average annual inflow is 1.7 hm (coefficient of variation 0.73); the water availability at 85% reliability level is estimated at 0.548 hmÂ/year and not 0.671 hmÂ/year as the original design indicates. With a sediment discharge estimated at 22,185 mÂ/year, it was concluded that, by the year 2026, the annual reservoir storage capacity reduction rate is 1.18% (due to siltation), causing a 41% reduction of the initial water availability. At that time, losses due to evaporation and spillway overflow totalize 81% of annual inflow. Based on these results, a PoilÃo reservoir operation proposal is presented
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Kuwajima, Julio Issao. "Análise do modelo SWAT como ferramenta de prevenção e de estimativa de assoreamento no reservatório do Lobo (Itirapina/Brotas/SP)." Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/18/18139/tde-14062013-112915/.
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Condições pedológicas, pluviosidade, alterações no uso e ocupação do solo, práticas de manejo de culturas e de preservação interferem diretamente na geração de sedimentos e na taxa de erosão. Em uma bacia hidrográfica esta geração de sedimentos excessiva pode resultar em problemas como o assoreamento dos corpos de água e de reservatórios. Nos reservatórios esta deposição de sedimentos pode representar perda de volume de reservação, promovida pelos sedimentos depositados no fundo da barragem. Com o tempo esta perda poderá vir a representar comprometimento da disponibilidade hídrica para irrigação, para o consumo humano, e para geração de energia. As obras de dragagem destes sedimentos são muito caras e resolvem somente os sintomas do problema e não suas causas. Desta forma as quantificações desse assoreamento e de seus deflagradores se mostram necessárias para o planejamento e gestão de recursos hídricos. A presente pesquisa se propõe a avaliar a aplicabilidade do modelo SWAT (Soil Water Assessment Tool) como ferramenta de estimativa de geração de sedimentos para reservatórios avaliando seus resultados, suas potencialidades e fragilidades para as condições locais e sugerir futuras pesquisas e/ou modificações no modelo. O modelo que foi desenvolvido originalmente pelo USDA (United States Departmente of Agriculture) para avaliar erosão e balanço hídrico de bacias hidrográficas, conta com um vasto número de aplicações no mundo, documentação e usuários. A área a ser estuda é bacia do reservatório do Lobo, que possuí uma área aproximada de 227 km² e localizado no município de Itirapina e de Brotas. Atualmente o reservatório é utilizado tanto para geração energética e como atração turística local. Dois cenários de simulação foram selecionados: Cenário 1 de 1977 até 1985 e Cenário 2 de 1996 até 2006. Para realizar as simulações foram utilizados a versão ArcSWAT 2005 version2.34 para realizar as simulações e o SWAT-CUP 4.3.1 para calibração.Os dados de entrada do modelo são: dados de chuvas e vazão diários obtidos da ANA (Agência Nacional das Águas), cartas de levantametno pedológico e cartas de uso e ocupação obtidas a partir de imagens CBERS e LANDSAT. Após calibração utilizando SUFI2 obteve-se o aporte de sedimentos na barragem para os dois cenários. Os resultados do primeiro cenário apresentaram influência negativa de dados inconsistentes de dados de vazão utilizados e limitações observadas na discretização do modelo nas representações do mosaico de uso e ocupação muito fragmentado para este cenário. O segundo cenário, no entanto obteve resultados satisfatórios comprovando a capacidade do modelo como ferramenta de avaliação de geração e aporte de sedimento em reservatórios.The sediment yield and erosion rates are directly affected by pedologic conditions, precipitation, land and use changes, management and soil preservation practices. Excessive sediment yield in a watershed could result in difficulties caused by siltation processes in rivers and reservoirs. Sediment deposition at the bottom of reservoirs and dams may result in volume loss. In time such loss could become impairment of water availability for irrigation, human consumption and power generation. Sediment dredging is an expensive solution that will address only the symptoms and not the causes of the issue. Therefore assessing the amount of sediment and their causes is required for Water Resources Management and Planning. The present research aims to evaluate the applicability of the SWAT (Soil and Water Assessment Tool) as sediment generation and contribution estimation tool for reservoirs evaluating the results, assessing the model strengths and weakness for the local contitions and make sugestions for future research and/or model modifications. Originally developed by the USDA (United States Department of agriculture) to assess erosion and water balance of watersheds, this model has a large number of users, available documentation and registered applications across the world. The study area, with an approximate area of 227 km² is the Lobo reservoir watershed, located at the municipalities of Itirapina and Brotas. The reservoir is currently used for hydropower generation and as a tourist attraction. Two simulation scenarios were chosen: Scenario 1from 1977 to 1985 and Scenario 2 from 1996 until 2006. To perform the simulations the ArcSWAT 2005 version 2.34 was selected and the SWAT-CUP 4.3.1 for the calibration. The data input was: daily precipitation and discharge flow datasets from ANA (Agência Nacional das Águas), pedological survey chats and land use charts obtained from CBERS and LANDSAT imagery. After calibration using SUFI2, sediment yield and contribution at the dam was obtained for both scenarios. The first scenario results showed negative effects caused by inconsistent input data flow and limitations regarding model discretization on the model representation of highly fragmented land use. The second scenario, however achieved satisfactory results demonstrating the model ability as sediment yield and contribution in reservoir evaluation tool.
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Arantes, Diego Mendonça. "Deposição e exportação de sólidos e nutrientes na sub-bacia do Ribeirão das Cruzes, baixo Tietê (SP)." Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/18/18139/tde-08112012-092936/.
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A qualidade ambiental de um corpo d\'água é resultado da situação de sua bacia de drenagem, de modo que as transformações que ocorrem no solo do entorno provocam mudanças significativas no ambiente aquático. Por isto, cada vez mais se trabalha com conceito de manejo integrado dos ambientes. Desta forma, o conhecimento dos processos de geração, transporte e deposição de sedimentos, por serem fontes de sólidos, nutrientes e contaminantes ao corpo d\'água, é de vital importância para a conservação, desenvolvimento e manejo integrado dos recursos hídricos. Neste sentido, essa dissertação apresenta um estudo a respeito da exportação e deposição de sólidos e nutrientes na sub-bacia do Ribeirão das Cruzes, no município de Santo Antônio do Aracanguá, SP, na Unidade de Gerenciamento de Recursos Hídricos do Baixo Tietê (UGRHI - 19). Esse corpo d\'água foi subdividido em compartimentos e analisado por transectos, ou seja, eixos transversais ao fluxo, sendo que experimentos envolvendo instalação de câmaras de sedimentação, coleta de sedimentos de fundo e medições de vazão foram conduzidos em dois períodos hidrológicos distintos: um em janeiro, durante a estação chuvosa, e outro em agosto, durante a estação seca. A taxa máxima de deposição de sólidos suspensos foi de 62,40 g/m² dia durante a Estação Chuvosa, e de 37,29 g/m² dia, durante a Estação seca. Ainda, a taxa média de deposição de nitrogênio total Kjeldahl foi de 0,53 e 2,02 g/m² dia e a de fósforo total foi de 139,67 e 103,89 mg/m² dia, durante as Estações Chuvosa e Seca, respectivamente. Quanto às taxas de exportação, para sólidos suspensos foram observadas médias de 2328,44 e 725,96 ton/dia, de nitrogênio total Kjeldahl foram de 121,41 e 299,84 ton/dia e para fósforo total foram de 14,86 e 10,05 ton/dia, durante as Estações Chuvosa e Seca, respectivamente. Os resultados obtidos, comparados a outros estudos em ambientes similares, revelam altas taxas de deposição e exportação de sólidos e nutrientes, demonstrando, desta forma, a incidência dos processos de eutrofização e assoreamento do recurso hídrico, bem como a expressão dos impactos provenientes do uso e ocupação do solo do entorno, capaz de influenciar na qualidade da água do ambiente.The environmental quality of waterbody is the result of the situation of its drainage basin, so that the transformations that occur on the soils surrounding cause significant changes in the aquatic environment. Therefore, each time more has been increasing the works with the concept of integrated management of environments. Thus, the knowledge about the processes of generation, transport and deposition of sediments, because they are sources of solids, nutrients and contaminants to waterbody, is extremely important for the conservation, development and integrated management of water resources. In this way, this dissertation presents a study concerning the deposition and export of solids and nutrients in the Ribeirão das Cruzes sub-basin, in Santo Antônio do Aracanguá city, SP, in Baixo Tietê Water Resources Management Unit (WRMU - 19). This waterbody was divided into compartments and analyzed by transects, which are transverse axes to the flow, and experiments involving installation of sedimentation traps, collect of bottom sediments and flow measurements were carried out in two distinct hydrological periods: one in January during the rainy season, and another in August, during the dry season. The maximum suspended solids deposition rate were 62.40 g/m² day during the rainy season, and 37.29 g/m² day during the dry season. So, the average rate of nitrogen deposition were 0.53 and 2.02 g/m² day, and the rate of phosphorus were 139.67 and 103.89 mg/m² day, during the rainy and dry seasons, respectively. As for exportation rates, the average rates found of suspended solids were 725.96 and 2328.44 ton/day, the rates of nitrogen were 121.41 and 299.84 ton/day, the rates of phosphorus were 14.86 and 10.05 ton/day, during the rainy and dry seasons, respectively. The results obtained, when compared to other studies in similar environments, show high rates of solids and nutrients deposition and export, demonstrating, this way, the incidence of eutrophication processes and siltation of the water resources, as well as the expression of impacts from the landuse, able to influence the water quality.
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Schmidt, Darlan Martínes. "Transporte de sedimentos no rio Coruripe e quantificação do seu empilhamento a partir do evento pluviométrico de junho/2009 no reservatório Coruripe I município de Coruripe AL." Universidade Federal de Alagoas, 2010. http://repositorio.ufal.br/handle/riufal/876.
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The research aimed to evaluate the sediment transportation and
deposition and the sedimentation (silt, siltation) in the Coruripe- I Reservoir,
analyzing the quantification of the sediment transportation by drag (drag, dragging),
and in suspension. The lake has, nowadays, 373 ha of water surface, and was built
in 2006 to demand water for irrigation. It is located in the Coruripe River
Hydrographic Basin, with 1562 Km2 of area. According to the batimétricos
(bathymetric) data, the depth of the reservoir varies from 0.8 to 12.3 m, from the
montant to the dam.
To quantificate the transportation of the sediments in suspension and bearing,
samples were taken above the reservoir, and the bottom sediments samples were
collected within the lake at the same time as the Topo-bathymetric survey, with a
Ecman dredging machine.
Samples of suspended sediments were analyzed through total evaporation and
subsequent weighting, than quantified in proportion to the sample volume. The size
of the bottom samples wasn t possible to determine due the composition
homogeneity of the samples, containing only mud. It was verified that the depositions
are predominantly made up of silt and clay. It was estimated that the assoread
volume of the lake, in 3 year of existence, is about 59,12%, with mean rate of
sediment accumulated around 512,549.43 ton.ano-1. The areas of greater
sedimentation and eutrophication were in the direction from downstream to montant
by sediments, derived from the river that provides the reservoir and from the laterals
to the centre, due to sediment erosion brought from areas of the reservoir slopes,
planted with cane sugar, in which are not maintained the tracks of ciliary
preservation, which would act as a kind of filter by reducing this direct contribution. It
is estimated that, if urgent decisions to contain the marginal sediments were taken,
this reservoir utile life can rise to approximately 85 years, otherwise, if the current
level of sedimentation (sedimentation) continues, the effective utile life will not
exceed 3 years.Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
A pesquisa teve como objetivo avaliar o transporte no rio Coruripe e o empilhamento de sedimentos provindos de uma barragem que rompeu à montante do Reservatório Coruripe - I, mediante estudos da quantificação do transporte de sedimentos por arraste e em suspensão. O lago possui atualmente espelho d água de 373 ha, construído para demanda de água para irrigação em 2006. Situa-se na BH do Rio Coruripe, com área de 1.562 km². Pela batimetria, a profundidade do reservatório varia de 0,8 a 12,3 m, de montante à barragem. Para a quantificação dos sedimentos transportados em suspensão e rolamento foram coletadas amostras acima do reservatório e para os sedimentos de fundo foram coletados no interior do lago na mesma época do levantamento topo-batimétrico com amostrador draga tipo Ecman.As amostras de sedimentos em suspensão foram analisadas através da secagem total e posterior pesagem, as quais foram quantificadas proporcionalmente ao volume amostrado. Já com as amostras de fundo não foi possível determinar a granulometria por apresentarem homogeneidade na composição, contendo somente lodo. Estima-se que o volume inutilizado do lago em 3 anos de existência é de 59,12 %, com taxa média de sedimentos acumulados de aproximadamente 512.549,43 ton.ano-1. As áreas de maior assoreamento e eutrofização estão no sentido de jusante à montante por sedimentos oriundos de uma barragem rompida à montante e do rio que abastece o reservatório e das laterais para o centro, devido a sedimentos carreados pela erosão das áreas de encostas, as quais são cultivadas com cana-de-açúcar. Diante disso, não são mantidas as faixas de preservação ciliar, que atuariam como uma espécie de filtro, diminuindo essa contribuição direta. Estimou-se ainda que, se forem tomadas decisões urgentes para a contenção de sedimentos marginais, a vida útil deste reservatório pode se elevar para aproximadamente 85 anos. Caso contrário, se o atual nível de assoreamento continuar, a vida útil efetiva não ultrapassará 3 anos.
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Sousa, Wanessa de. "Comunidades zooplanct?nicas como bioindicadoras da qualidade da ?gua de quatro reservat?rios da regi?o semi-?rida do Rio Grande do Norte." Universidade Federal do Rio Grande do Norte, 2007. http://repositorio.ufrn.br:8080/jspui/handle/123456789/12514.
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The response of zooplankton assemblages to variations in the water quality of four man-made lakes, caused by eutrophication and siltation, was investigated by means of canonical correspondence analysis. Monte Carlo simulations using the CCA eingenvalues as test statistics revealed that changes in zooplankton species composition along the environmental gradients of trophic state and abiogenic turbidity were highly significant. The species Brachionus calyciflorus, Thermocyclops sp. and Argyrodiaptomus sp. were good indicators of eutrophic conditions while the species Brachionus dolabratus, Keratella tropica and Hexarthra sp. were good indicators of high turbidity due to suspended sediments. The rotifer genus Brachionus was the most species-rich taxon, comprising five species which were associated with different environmental conditions. Therefore, we tested whether this genus alone could potentially be a better biological indicator of these environmental gradients than the entire zooplankton assemblages or any other random set of five species. The ordination results show that the five Brachionus species alone did not explain better the observed pattern of environmental variation than most random sets of five species. Therefore, this genus could not be selected as a target taxon for more intensive environmental monitoring as has been previously suggested by Attayde and Bozelli (1998). Overall, our results show that changes in the water quality of man-made lakes in a tropical semi-arid region have significant effects on the structure of zooplankton assemblages that can potentially affect the functioning of these ecosystems
As respostas das assembl?ias zooplanct?nicas ?s varia??es na qualidade da ?gua de quatro reservat?rios, causadas por eutrofiza??o e assoreamento, foram investigadas por meio de uma an?lise de correspond?ncia can?nica. Simula??es de Monte Carlo utilizando os autovalores da CCA como estat?sticas teste revelaram que as mudan?as na composi??o de esp?cies zooplanct?nicas ao longo dos gradientes ambientais de estado tr?fico e turbidez abiog?nica foram altamente significativas. As esp?cies Brachionus calyciflorus, Thermocyclops sp. e Argyrodiaptomus sp. foram boas indicadoras de condi??es eutr?ficas enquanto que as esp?cies Brachionus dolabratus, Keratella tropica e Hexarthra sp. foram boas indicadoras de elevada turbidez por sedimentos em suspens?o. O g?nero de rot?feros Brachionus foi o mais rico em esp?cies, compreendendo cinco esp?cies que estiveram associadas a diferentes condi??es ambientais. Portanto, n?s testamos se esse g?nero sozinho poderia ser potencialmente um melhor indicador biol?gico desses gradientes ambientais do que toda a assembl?ia zooplanct?nica ou qualquer outro conjunto aleat?rio de cinco esp?cies. Os resultados da ordena??o demonstram que as cinco esp?cies de Brachionus quando sozinhas n?o explicaram melhor os padr?es observados de varia??o ambiental que a maioria dos conjuntos aleat?rios de cinco esp?cies. Portanto, este g?nero n?o pode ser selecionado como um t?xon alvo para um monitoramento ambiental mais intensivo conforme previamente sugerido por Attayde e Bozelli (1998). De um modo geral, nossos resultados mostram que mudan?as na qualidade da ?gua de reservat?rios em uma regi?o semi-?rida tropical t?m efeitos significativos sobre a estrutura das assembl?ias zooplanct?nicas, os quais podem afetar potencialmente o funcionamento desses ecossistemas
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Huguet, Jean-Rémy. "Dynamique hydro-sédimentaire en milieu portuaire : application au port de plaisance de La Rochelle." Thesis, La Rochelle, 2019. http://www.theses.fr/2019LAROS034.
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Présents sur toutes les façades maritimes et fluviales du monde, les ports sont aujourd’hui des interfaces majeures du développement des territoires. L’envasement naturel de ces zones calmes peut obstruer les voies navigables et empêcher ces infrastructures de jouer leur fonction primaire d’abri pour les bateaux. Cela implique souvent la mise en œuvre de travaux de dragages onéreux et chronophages, afin de retrouver des profondeurs compatibles avec la navigation. Le port des Minimes (La Rochelle, France), qui est un des plus gros ports de plaisance de la façade Atlantique, n’est pas épargné par ce phénomène et requiert des activités de dragage huit mois par an. Face à cette problématique, le port de plaisance et La Rochelle Université ont eu la volonté de mieux comprendre la dynamique du milieu et les processus menant à l’accumulation de sédiments sur le site des Minimes. En combinant une approche instrumentale in situ à une modélisation numérique opérationnelle, l’objectif de ce travail de thèse a donc consisté à caractériser la dynamique hydro-sédimentaire de cet espace littoral anthropisé. Une quantification de l’impact des structures flottantes (bateaux, pontons) sur l’hydrodynamique portuaire, a tout d’abord été menée. Le second champ d’étude a visé à décrire la circulation des masses d’eaux et leur renouvellement sous l’action du vent et de la marée. Les observations récoltées ont permis d’étudier la dynamique sédimentaire spatiale et temporelle, en lien avec l’action du vent, de la marée et des vagues. Plusieurs scénarios de lutte contre l’envasement ont été mis en place et analysés dans le but de fournir des éléments de réponse et pistes de recherche sur la gestion de l’envasement et du dragage associéPorts are presents on all maritime and river fronts of the world, and represent major interfaces in the development of territories. The natural siltation of these calm areas can obstruct waterways and prevent these infrastructures from fulfilling their primary function as a shelter for boats. This often involves the implementation of expensive and time-consuming dredging operations to restore depths compatible with navigation. Les Minimes marina (La Rochelle, France), which is one of the largest marinas on the Atlantic coast, is not spared by this phenomenon and requires dredging activities for a large part of the year. In response to this problem, the marina and La Rochelle University, has wanted to understand better the natural environment and the processes leading to the accumulation of sediments in the marina. By combining an instrumental in situ approach with operational numerical modelling, the objective of this thesis was, therefore, to characterise the hydro-sedimentary dynamics of the area. Quantification of the impact of floating structures (boats, pontoons) on marina hydrodynamics was firstly carried out. The second field of study aimed to study the circulation of water masses and their renewal about the effect of wind and tide. The observations collected made it possible to study spatial and temporal sediment dynamics, under the action of wind, tide and waves. Thus, numerous siltation control measures have been implemented and analysed to provide solutions and research perspectives in view with siltation and dredging management
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Mekerta, Belkacem. "Étude des propriétés géomécaniques des sédiments d'envasement de la retenue du barrage de Génissiat." Vandoeuvre-les-Nancy, INPL, 1995. http://docnum.univ-lorraine.fr/public/INPL_T_1995_MEKERTA_B.pdf.
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On sait que les cours d'eau transportent des matières solides. Les dépôts qui en résultent dans les réservoirs diminuent leur capacité, ceci correspond à l'envasement des retenues de barrages. La sédimentation et la distribution des sédiments dans les retenues constituent des problèmes complexes auxquels les constructeurs d'aujourd'hui sont confrontés. De plus les conditions ultérieures de tassement et de consolidation des dépôts sont influencées par plusieurs facteurs ; la concentration du débit solide, la hauteur du niveau d'eau dans les barrages, la nature des matériaux transportés et le milieu. Pour la conception et l'exploitation d'un barrage, la connaissance de la prévision des apports solides est d'un intérêt capital en vue d'adopter les solutions les plus appropriées aux problèmes du dévasement. Le barrage de Génissiat sur le Rhône a fait l'objet de notre étude. Pour une bonne connaissance de la répartition spatiale des propriétés géomécaniques dans la retenue, 25 sondages d'une profondeur maximum de 6,45 m ont été exécutés en novembre 1992 de l'amont de la retenue jusqu'au pied du barrage sur une distance de 450 m environ. Une investigation complète sur les propriétés physiques et mécaniques en fonction de la profondeur à été réalisée d'une manière systématique sur l'ensemble des prélèvements. Les résultats ont été étudiés tout d'abord d'une manière globale puis en essayant de trouver une répartition spatiale des propriétés étudiées. Enfin, dans une dernière partie, deux méthodes différentes ont été utilisées afin d'essayer de reproduire la sédimentation naturelle dans une retenue de barrage. La connaissance à priori des propriétés mécaniques des sédiments dans la retenue devrait permettre une meilleure organisation des opérations de dragage et une meilleure économie
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Lin, Cho-Tian, and 林朝添. "A Study of Sediment Siltation at Wu-Shi Fishery Harbor." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/ph8s7z.
Full textAbstract:
碩士國立臺灣海洋大學
河海工程學系
107
The investigation on sedimentary deposition at Wushi fishing port receives great attention recently. In 2016, amount of sediment is accumulated at Wushi fishing port because of the continuous visits of three typhoons; the observations exhibit that a submerged sandbar is found nearby the southern part at Wushi fishing port, having a negative impact to navigation. The main objective of this study is to investigate the morphological migrations subject to the effects of construction histories as well as field water depths. The analyses suggest that the main source of sedimentation during the interaction of typhoon waves at fishing port is the sediment at southern of breakwater and the front part of To-Chen park; however, the main source of sedimentation during the seasonal waves at fishing port is the sediment at eastern of fishing port.
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Velasco, Victor V. "Evalution and cost comparison of anti-siltation systems and traditional dredging methods." Thesis, 2000. http://hdl.handle.net/10945/7689.
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CIVINSMaintaining the design depth of ship servicing facilities is a challenging task. Dredging technology has improved significantly in the past few decades and this should have driven the cost downwards. However, increased environmental awareness has placed limitations on how dredge spoils are handled, transported and disposed of and has effectively increased the costs of dredging operations. The United States Army Corps of Engineers and the Naval Facilities Engineering Command have conducted research into alternate sediment removal methods that may replace conventional dredging in sites where the conditions merit. The alternate systems include arrays of jets to prevent settling of suspended sediment and systems to entrain and transport sediment without physical removal. This study investigates the most promising techniques researched by the United States Army Corps of Engineers and the Naval Facilities Engineering Command for application at Naval Station Mayport, Florida. Naval Station Mayport has a long history of high sedimentation rates and difficulty in maintaining design depths at the piers, despite several studies to determine cost effective alternatives. Although several conservative assumptions were made concerning environmental conditions at the site that directly affect the design concept presented, the economic analysis indicated substantial saving can be realized if an alternate system consisting of turbo scouring units and a catchment basin were installed. The analysis takes into consideration the initial capital cost and the annual operation and maintenance of the alternate system for a 30-year life cycle, adjusted for inflation and compares the total cost against the cost to continue the current dredging operations at the existing frequency and quantities
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謝鴻源. "GM (0, N) IN THE RESERVOIR CAPACITY ADD THE SILTATION OF STUDY." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/75726570072281307883.
Full textAbstract:
碩士建國科技大學
電機工程系暨研究所
101
Taiwan due to the difference in time of rainfall, coupled with short rivers, steep and rapid stream, the rapid formation of rainfall runoff into the sea, so the reservoir water resources sustainable utilization of Taiwan's most stable and reliable foundation. Reservoir is an important reservoir in northern emerald, but earthquakes and typhoons heavy rain events, making the catchment surface erosion by rain, a lot of sediment collapse or erosion of storage, making it particularly serious siltation problem. Reservoir sedimentation problem has been studied for many years, is calculated reservoir sedimentation reservoir sedimentation and soil conservation project is an important part of its planning and forecasting results for Reservoir Reservoir is a must. Reservoir sedimentation basin is also on a variety of natural and human factors combined result, not only by rainfall (especially rain) temporal and spatial variation is also affected by a serious impact on river debris slide. Calculated on reservoir sedimentation previous research a variety of example: According to the results of reservoir sediment deposition only estimate the total reservoir and the process of change; After the law on reservoir sedimentation studies, various parameters derived direct calculation method and river power mathematical model. However, these studies bureau restricted bigger. However, a characteristic gray theory each data entry system, will produce different results, and different time course, it contains a variety of different data periods. In this paper, the gray system theory, the direct input of survey data from the system to the reservoir for the study of jade objects, changes in the reservoir siltation gray analysis and prediction of reservoir management to provide scientific basis for further control.
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Kidd, IM. "Strategies for sustainable morphological remediation of the Tamar river estuary and other similarly degraded estuaries." Thesis, 2017. https://eprints.utas.edu.au/23855/1/Kidd_whole_thesis_ex_pub_mat.pdf.
Full textAbstract:
When anthropogenically induced morphological change within estuaries becomes irreversible, hysteresis is established and mitigating projects are required to undo any degradation. The morphologically degraded Tamar River estuary in Tasmania Australia typifies the universality of problems and solutions pertaining to estuaries in Australia, North America, Europe and the UK. Historically, restoration projects proposed for the Tamar were analogues of projects elsewhere, for which full repercussions are emerging. Barrages and weirs for example, unintentionally altered the hydrodynamics with negative long-term morphological consequences. Within the Tamar, recently mooted projects supposedly reduced the flood dominance of tides. Since the 1880s, silt management was by dredging (now cost prohibitive); replaced in recent years by silt raking. Neither process addresses the root-cause of the degradation.
The aim of this thesis was to develop and model sustainable solutions (proven and novel) for hysteretic degraded estuaries such as the Tamar, whilst identifying projects having potentially unacceptable trade-offs. The multifaceted methodology reviewed datasets pertaining to tidal heights, bathymetry and land elevations for the Tamar; examined asymmetrical tides, net sediment flux and establishment of equilibrium; developed a First Order Morphological Response Model (FORM) to review and evaluate proposed projects; used FORM on four international examples, and evaluated the effectiveness of barrages as mitigators of sea-level rise.
Tidal asymmetry results showed that flood velocity bias persisted and maximised at equilibrium, the inference being their removal is counterproductive. A feedback loop developed at equilibrium (driven by M4 and M6 harmonics); deposition on the banks led to slumping into the constantly scoured channel resulting in a net zero sediment flux. FORM modelled the new equilibrium of five putative barrages within the Tamar. Equilibrium established from a persistent flood velocity bias, ultimately resulting in a net loss of physical amenity below the barrage and unsatisfactory ecological trade-offs both upstream and downstream. Another study of four international barraged systems showed morphological degradation with some mitigation of sea-level rise in each head-pond but potential to increase tidal ranges downstream, thereby exacerbating sea-level rise. Neither study justified the installation of a barrage in the Tamar. Projects designed to remove or mitigate reduced estuarine and freshwater flow would be beneficial in restoring some amenity to the Tamar with potentially up to 8 million m3 of silt permanently removed. Those projects synergistic with nature proved prospective, whereas those antagonistic to nature would fail. Results inform a more sustainable management of estuaries in general with emphasis on a proactive, rather than a reactive paradigm.
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Chang, Chien Chin Hsien, and 張簡進賢. "Influence of River Siltation on Groundwater Level—A Case Study of Dashu Reach of Kaoping River." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/h2ugrn.
Full textAbstract:
碩士國立屏東科技大學
土木工程系所
102
Taiwan, due to its island properties and the addition influence of 921 Earthquake in 1999 and Typhoon- Morakot- caused flood (the 88 flood) in 2009, the hillsides are seriously loosen and collapsed, resulting in abundant of detritus sliding down to the rivers and silting up the river courses. The study on the relation between the height of siltation of the river course and the fluctuation of the groundwater level can be the reference to estimate the amount groundwater development when Kaoping River Dam is in the dry spell or has higher turbidity. The research takes the data of the cross section of Da Shu segment of Kaoping River from 2009 to 2013 along with the analysis and algorithm of neighboring groundwater monitoring wells to deduce the relation between river siltation and groundwater level. The analysis shows that during the period from 2009 to 2013, annual variation of elevation was 18.01, 18.75, 19.25, 19.53 and 19.40 meters separately; however, annual average groundwater level was 16.6, 16.74, 16.9, 17.24 and 16.7 meters separately. Based on the relation showed above, the conclusion can be made that the rising of river siltation may accompany with the increasing of groundwater level.
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Lobo, Felipe de Lucia. "Spatial and Temporal Analysis of Water Siltation Caused by Artisanal Small-scale Gold Mining in the Tapajós Water Basin, Brazilian Amazon: An Optics and Remote Sensing Approach." Thesis, 2015. http://hdl.handle.net/1828/6324.
Full textAbstract:
The main goal of this research was to investigate the spatial and temporal impacts of water siltation caused by Artisanal Small-scale Gold Mining (ASGM) on the underwater light field of the Tapajós River and its main tributaries (Jamanxim, Novo, Tocantinzinho, and Crepori rivers). In order to accomplish this, two fieldwork research trips were undertaken to collect data associated with water quality and radiometric data. This data provided information to quantify the underwater light field in water affected by a gradient of mining tailings intensity, clustered into five major classes ranging from 0 to 120 mg/L of total suspended solids (TSS) (Chapter 3). In general, with increased TSS from mining operations such as in the Crepori, Tocantinzinho, and Novo rivers, the scattering process prevails over absorption coefficient and, at sub-surface, scalar irradiance is reduced, resulting in a shallower euphotic zone where green and red wavelengths dominate. The effects of light reduction on the phytoplankton community was not clearly observed, which may be attributed to a low number of samples for proper comparison between impacted and non-impacted tributaries and/or to general low phytoplankton productivity in all upstream tributaries.
In Chapter 4, aiming to extend the information derived from Chapter 3 over a 40-year period (1973-2012), the TSS concentration along the Tapajós River and its main tributaries was quantified based on in situ data and historical Landsat-MSS/TM/OLI data. Measurements of radiometric data were used to calibrate satellite atmospheric correction and establish an empirical relationship with TSS. The regression estimates TSS with high confidence from surface reflectance (ρ_surf (red)) up to 25%, which corresponds to approximately 110 mg.L-1. The combination of the atmospheric correction and the robust reflectance-based TSS model allowed estimation of TSS in the Tapajós River from the historical Landsat database (40 years).
In Chapter 5, the role of the temporal changes of ASGM area in the water siltation over the last 40 years was investigated in four sub-basins: the Crepori, Novo, and Tocantins sub-basins (mined); and the Jamanxim sub-basin (non-mined), considering the landscape characteristics such as soil type and proximity to drainage system. ASGM areas were mapped for five annual dates (1973, 1984, 1993, 2001, and 2012) based on Landsat satellite images. Results showed that ASGM increased from 15.4 km2 in 1973, to 166.3 and 261.7 km2 in 1993 and 2012, respectively. The effects of ASGM areas on water siltation depends on several factors regarding ASGM activities, such as the type of mining, type of gold deposits, and intensity of gold mining, represented by number of miners and gold production.Graduate
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lobo@uvic.ca
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Hulec, Filip. "Hydrologický a plaveninový režim Odlezelského jezera." Master's thesis, 2020. http://www.nusl.cz/ntk/nusl-435874.
Full textAbstract:
The Odlezelské Lake is a natural, landslide-dammed lake in western Bohemia. Its lake basin is silting intensely and its volume decreases; it will be completely silted in the future. This work aims to evaluate the siltation of the lake primarily by evaluating the suspended load regime of its tributaries and comparison with data from bathymetric measurements. Within this work, data from the station network of the Department of Physical Geography of the Faculty of Science of the Charles University were used, which was statistically processed in order to describe the hydrological and suspended load regime. In addition, flow speeds in the inflow part of the lake were measured during two precipitation-runoff events using ADCP. The results show that most of the suspended load is transported during flood episodes, in contrast to the runoff, there is a significant interannual variability in the suspended load regime. Oppositely, the comparison of the suspended load regime and the bathymetric data proved as impossible due to a high sensitivity of the data.
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Stapper, Daniel. "Artisanal gold mining, mercury and sediment in Central Kalimantan, Indonesia." Thesis, 2011. http://hdl.handle.net/1828/3711.
Full textAbstract:
A field survey was undertaken in Central Kalimantan, Indonesia (Borneo) to assess the extent and practices of Artisanal and Small-scale Gold Mining (ASGM), and to measure sediment and mercury flows in the provinces’ rivers. More than forty mining operations were visited in six of the provinces largest river basins during June, July and August of 2008. Based on the survey results, this thesis estimates that 43,000 small-scale gold miners in Central Kalimantan produced 13.3 tonnes of gold in 2008 (426,000 troy ounces - ozt) worth approximately 362 million CAD (based on 2008 international gold price of 850 CAD/ozt). Mercury use was ubiquitous for leaching gold from ores in the province. Approximately 65.3 tonnes was used for this purpose in 2008, with the majority of consumption- 80% by whole-ore amalgamation operations exploiting hard-rock deposits, but producing only 13% of the gold. These estimates have been interpolated using (i) measurements and detailed observations at more than forty ASGM operations surveyed in five different regencies; (ii) numerous interviews with miners, gold shops owners and officials across these regencies; and (iii) mapping of ASGM operations using satellite imagery.
Hydraulic mining methods mobilize enormous volumes of sediment and native sediment-bound mercury. Sediment and mercury fluxes associated with ASGM activities were estimated based on a river sediment sampling campaign carried out in conjunction with the ASGM survey, and on subsequent modelling of river sediment transport. On streams and tributaries, mining activities increased sediment transport by factors between 100 and 1500, resulting in a net doubling of sediment loads on large first order river channels, on which the effects of mining are diluted in space and time by channels without mining. Particulate mercury flux sampled on six of Central Kalimantan’s largest river channels averaged 60ng/L ±33%, a high figure relative to most global rivers, despite average suspended sediment concentrations of only 75mg/L ±58%. Based on a hydrological and sediment transport model, 19.4 tonnes of mercury (±30%) transits these river systems annually, dominantly transported as suspended sediment load (95%), with the remaining 5% transported as bedload.
Acute mercury exposure by inhalation during the burning of mercury-gold amalgam represents an important health concern at ASGM camps and gold shops. In relation to mercury, sector improvements should focus on eradicating whole ore amalgamation, and open burning of amalgam. Eliminating whole ore amalgamation requires technological improvements at the gold liberation (crushing and milling) and concentration stages of ore processing. Elimination of open-air burning can be achieved through education, and the use of retorts, fumehoods, and mercury re-activation cells– each of these basic technologies provide mercury users with economic incentives by reducing mercury consumption.Graduate