Universiẗat, Diss., 2003--Bonn.

University, Diss., 2002--Kiel.

Techn. University, Diss., 2005--Berlin.

No description available.

Thesis (Ph. D.)--University of Texas at Austin, 2008. / Vita. Includes bibliographical references.

Sea-level rise and stronger hurricanes associated with global climate change will likely result in farther reaching storm surges that will greatly affect coastal ecosystems. These surges can transport nutrients, salt water, and sediment to nutrient poor, fresh (i.e. low salinity) pine savannas. Purple pitcher plants (Sarracenia purpurea ) are pine savanna inhabitants that could potentially be at a disadvantage because their pitcher morphology and stout structure may leave them prone to collecting saline water and sediment after a surge. In this study, separate field and greenhouse experiments were conducted to test the effects of storm surge water salinity and sediment type on pine savanna soil characteristics, plant community structure, and pitcher plant vitality. In the field, plots (containing &ge genet of S. purpurea ) were experimentally storm surged with fresh or saline water crossed with one of four sediment types (local, foreign, fertilized foreign, or no sediment). Saline water inundation resulted in significantly higher pitcher plant mortality than the fresh water treatment combinations. However, a subsequent prescribed fire and regional drought affected the study area during the next growing season, resulting in the decline of all the pitcher plants to zero or near zero percent cover. Soil data revealed that the combination of salt water and fertilized sediment resulted in short-term increases in soil-water conductivity and nitrogen availability. Interestingly, there were no significant differences in plant community structure between treatments, suggesting that the community as a whole is not as vulnerable as the pitcher plants to the cumulative effects of multiple stressors (i.e. storm surge, fire, and drought) operating in this system. Indicator species analysis revealed that some species were significant indicators of certain treatments; thus suggesting that pitcher plants are not the only species affected by storm surge. In the greenhouse, pitcher plants received various forms of sediment (i.e. no sediment, sterile sediment, or one of two levels of fertilized sediment) within their pitchers to determine if nutrient uptake is either inhibited or enhanced. Plants that received sterile sediment had higher carbon:nitrogen ratios and higher leaf mass per unit area. Eutrophic sediment deposition resulted in a temporary decrease in relative growth rate as well as changes in pitcher morphology. There were no differences in chlorophyll content and photosynthetic rates between treatments. Both the field and greenhouse experiments indicate that global climate change may indirectly contribute to the further decline of southeastern purple pitcher plant populations in the future.

The present study focuses on the sediment deposition and consequent dredging issues in Lower Ohio River at the Olmsted Locks and Dam area-River mile (RM)-964.4 during the ongoing in-the-wet construction methodology. The study reach is between Locks and Dam 53 (RM 962.6) at upstream, and RM 970 at downstream. One dimensional (1-D) HEC-RAS numerical modeling in conjunction with Arc-GIS was employed. Stream flow measurements, velocity, incoming sediment concentration, bed gradation, and annual hydrographic survey data acquired from public archives of USGS and USACE Louisville District were used as inputs. The model was subjected to the 1-D quasi-unsteady and completely unsteady sediment transport module, available in the latest HEC-RAS 5.0 Beta release. Calibration and validation of the hydrodynamic and sediment models were performed using measured water surface elevation, velocity, and sediment loads at measured sections. Post-model calibration and validation, deposition to excavated cross-sections for future dam shells at Olmsted was predicted, which warrants dredging. The study attempted to analyze the sediment transport trend with the focus on depositionat Olmsted Locks and Dam area using the sensitivity analysis approach of transport capacity functions. Moreover, the capability of 1-D HEC-RAS quasi-unsteady and completely unsteady models were assessed in prediction of sediment deposition in the construction area (dam shells excavation area). A temporal deposition prediction model was developed that can potentially replace the current ad-hoc approach used to determine the dredging schedule. Likewise, a representative environmental risk associated with sedimentation in the study area was examined. The model can potentially be used as a decision support tool to analyze the long term impact of sedimentation in the vicinity of Olmsted Locks and Dam if further updates on the river bathymetry, and specific field data are supplemented to the model.

No description available.

Made available in DSpace on 2015-03-26T13:28:24Z (GMT). No. of bitstreams: 1 texto completo.pdf: 6794680 bytes, checksum: 55db799523fa29d2ac3a1dcd7961c68e (MD5) Previous issue date: 2013-08-27 / Dams are part of the history of civilizations, being among the first works architected by humanity. Reservoirs, formed by dams, act as sediment retention basins, promoting its gradual sedimentation. The accumulation of sediments on reservoir s bottom modifies the morphology of the relief, which should be periodically reviewed by the update of the elevation x area x volume curve (EAV), based on bathymetric surveys. This study aimed to evaluate the process of sedimentation on the Pipoca hydroelectric power plant reservoir, by performing bathymetric surveys and the characterization of the reservoir bottom sediments. Two bathymetric surveys were executed, the first, in 2012, with a single beam echosounder and the second, in 2013, with a multibeam echosounder. In addition to the comparison between the two methodologies used in the echosounders, it was analyzed the results obtained before and after the filling of the reservoir, by the generation of Digital Elevation Models (DEMs). The DEM before reservoir s filling was obtained from contour s lines of the region and some bathymetric sections of the river. These DEM enabled the generation of EAV curves before and after reservoir s filling, enabling the identification of deposited sediment volumes during the current operation period of the hydroelectric power plant. In the first bathymetric survey it was obtained a deposited sediment volume of 0.404 hm3, which represents an average annual sedimentation of 0.80%. In the second bathymetric survey was obtained a deposited sediment volume of 0.369 hm3, which represents an average annual sedimentation of 0.63%. The difference on the volumes obtained by the two equipments can be explained by the greater accuracy provided by the multibeam echo sounder. This multibeam echo sounder technology is able to provide 100% coverage of the area and requires less interpolation on the collected data than the other technology. / As barragens fazem parte da história das civilizações, estando entre as primeiras obras arquitetadas pela humanidade. Os reservatórios, formados pela construção de barragens, atuam como verdadeiras bacias de retenção de sedimentos, promovendo o seu assoreamento gradual. O acúmulo de sedimentos do fundo do reservatório modifica a morfologia do relevo, que deve ser reavaliada periodicamente a partir da atualização das curvas cota x área x volume (CAV), com base em levantamentos batimétricos. O presente estudo visou avaliar o processo de assoreamento no reservatório da PCH Pipoca (MG), por meio da realização de levantamentos batimétricos e pela caracterização dos sedimentos de fundo do reservatório. Foram realizados dois levantamentos batimétricos, o primeiro, em 2012, com ecobatímetro monofeixe e o segundo, em 2013, com ecobatímetro multifeixe. Além da comparação entre as metodologias utilizadas no uso dos ecobatímetros, foram analisados os resultados obtidos antes e depois do enchimento do reservatório, a partir da geração de Modelos Digitais de Elevação (MDEs). O MDE antes do enchimento do reservatório, em 2006, foi obtido a partir de curvas de nível da região e de algumas seções batimétricas. Estes MDEs permitiram a geração das curvas CAV anterior e posterior ao enchimento do reservatório, possibilitando identificar volumes de sedimento depositado ao longo do período de operação do empreendimento. Na primeira batimetria do reservatório foi obtido um volume de sedimento depositado de 0,404 hm3, representando uma taxa média de assoreamento anual de 0,80%. Já na segunda batimetria do reservatório foi obtido um volume de sedimento depositado de 0,369 hm3, representando uma taxa média de assoreamento anual de 0,63%. Esta diferença pode ser justificada pelo fato de o ecobatímetro multifeixe proporcionar uma precisão maior no levantamento, ao ser capaz de mapear 100% da área, demandando pouca interpolação dos dados coletados.

Submitted by Erika Demachki (erikademachki@gmail.com) on 2018-06-29T17:20:59Z No. of bitstreams: 2 Tese - Susy Ferreira Oliveira - 2018.pdf: 9298353 bytes, checksum: 60e60c13d3a1c475932225b3ca022f41 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2018-07-03T14:47:38Z (GMT) No. of bitstreams: 2 Tese - Susy Ferreira Oliveira - 2018.pdf: 9298353 bytes, checksum: 60e60c13d3a1c475932225b3ca022f41 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2018-07-03T14:47:38Z (GMT). No. of bitstreams: 2 Tese - Susy Ferreira Oliveira - 2018.pdf: 9298353 bytes, checksum: 60e60c13d3a1c475932225b3ca022f41 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2018-05-17 / Fundação de Amparo à Pesquisa do Estado de Goiás - FAPEG / By building dams in a watercourse, the hydrosedimentometric dynamics of the water bodies changes. Due the reduction of transport energy, the particulate material transported starts being deposited, reducing the volume and the useful life of the reservoir. In order to take mitigating and preventive measures, it is necessary to diagnose the sectors with the greatest amount, volume and distribution of sediments in the area of influence. The general objective of this work was to evaluate the sedimentation stage, to detect the current depositional models and to evaluate the quality of the sediments, aiming at possible mitigation measures in relation to the sedimentation of the reservoir of the Barra dos Coqueiros hydropower plant, located on river Claro, between the municipalities of Caçu and Cachoeira Alta. In order to reach the proposed general objective, the physical characterization of the area of influence on the reservoir was carried out, from geological, geomorphological, slope, soil, climate, land use and vegetation cover aspects. And to determine the possible source areas related to erosive processes, the map of potential fragility and emergent fragility was generated. In order to understand the main sites of impact, hydrosedimentological studies were carried out through CSS, Turbidity and Water Transparency variables. The study of current depositional models was carried out from the study of facies. The quality of the sediments was evaluated by the heavy metals Cadmium, Nickel, Copper, Lead and Mercury. According to fragility analysis, 30% of the area is classified as medium and high fragility, demonstrating the need for planning and utilization of conservation practices in relation to the use and vegetation cover. By means of hydrosedimentological studies, it was noticed the reduction of CSS and Turbidity downstream, according to the velocity of water flow and depth analyzed in the bathymetric surveys, in which a reduction of 0.51% of the dead volume of the reservoir was observed. Depositional models that predominate are associated with silt/clayey facies for riverbed deposits, sandy facies for stream deposits and silt/clayey and sandy facies for delta deposits. Regarding sediment quality, it was verified that cadmium presented concentrations higher than the reference parameter determined for sediments by CONAMA Resolution 454/2012. In the soil, it was also verified that heavy metals were superior to the reference values of the resolution CONAMA 420/2009, that’s related to the natural formation of the soils and to the use and occupation of the earth. / Com a construção de barragens em um curso de água, altera-se a dinâmica hidrossedimentométrica dos corpos d’água. Com a redução da energia de transporte, o material particulado transportado passa a ser depositado, reduzindo o volume e a vida útil do reservatório. Para que medidas mitigatórias e preventivas possam ser tomadas, é preciso que sejam diagnosticados os setores com maior aporte, volume e distribuição dos sedimentos na área de influência. Neste trabalho, o objetivo geral foi avaliar o estágio de sedimentação, detectar os modelos deposicionais vigentes e avaliar a qualidade dos sedimentos, visando às possíveis tomadas de medidas mitigadoras em relação ao assoreamento do reservatório da usina hidrelétrica Barra dos Coqueiros, que se situa no rio Claro, entre os municípios de Caçu e Cachoeira Alta. Para atingir o objetivo geral proposto, foi realizada a caracterização físicas da área de influência do reservatório a partir dos aspectos geológicos, geomorfológicos, declividade, solos, clima, uso da terra e cobertura vegetal, A fim de se determinar as possíveis áreas fontes em relação aos processos erosivos, foi gerado o mapa de fragilidade potencial e fragilidade emergente. Com o intuito de se compreender os principais locais de aporte, foram realizados estudos hidrossedimentológicos. A pesquisa dos modelos deposicionais vigentes foi realizado a partir do estudo de fácies. A qualidade dos sedimentos foi avaliada quantificando os níveis dos metais pesados Cádmio, Níquel, Cobre, Chumbo e Mercúrio. De acordo com análise da fragilidade, 30% da área classifica-se em média e alta fragilidade, demonstrando a necessidade de planejamento e utilização de práticas conservacionistas em relação ao uso e cobertura vegetal. Os estudos hidrossedimentológicos demonstraram a redução das CSS e Turbidez de montante para jusante, de acordo com a velocidade de escoamento da água e profundidade analisadas nos levantamentos batimétricos, no qual foi percebida uma redução de 0,51% do volume morto do reservatório. Os modelos deposicionais que predominam são associados às fácies silte/argilosas para os depósitos de leito, fácies arenosas para os depósitos de corrente e fácies silte/argilosas e arenosas para os depósitos de delta. Quanto à qualidade dos sedimentos, verificou-se que o cádmio apresentou concentrações superior ao parâmetro de referência determinado para sedimentos pela Resolução CONAMA 454/2012. Nos solos, observou-se que os metais pesados foram superiores aos valores de referência da resolução CONAMA 420/2009, fato este relacionado à formação natural dos solos e ao uso e ocupação da terra.