An autonomous underwater cable suspended dredging system is proposed with the application of combating the excess of nutrients in the Baltic Sea. The focus of the thesis is on modelling and designing of the control system used to guide an end-effector supplied with a pump along a predetermined path. The end-effector is guided with the help of four cables that are each controlled by a servomotor. The buoyancy of the end-effector in combination with the cables keeps the end-effector a few meter above the seafloor. The sediment is collected with tubes hanging down from the end-effector. Due to the large dimensions of the system a combination of force control and position control passed through a force distribution algorithm is suggested. A simulation of the system shows promising results with ability to trace the predetermined path closely. / Ett förslag till ett autonomt vajerstyrt muddringssytem för undervattensbruk har tagits fram som ska används för att motverka övergödningen i östersjön. Uppsatsen fokuserar på modelleringen och designen av reglersystemet för att styra en plattform utrustad med en pump längs en förutbestämd sträcka. Plattformen styrs med hjälp av fyra vajrar som i sin tur styrs av varsin servomotor. Flytkraften hos plattformen i kombination med vajrarna håller plattformen några meter från havsbotten. Bottensediment pumpas upp genom slangar som hänger ner från plattformen. På grund av systemet storlek regleras styrningen av plattformen genom båda kraft och position samt använder en algoritm för att distribuera krafterna mellan vajrarna. En simulering av systemet har utförts och visar på god förmåga att reglera positionen av plattformen i relation till den förutbestämda sträckan.

Ocean warming and increased sedimentation from coastal activities are major threats to coral persistence. This study assessed the effects of increased temperature and sedimentation on the survival and growth of Acropora cervicornisrecruits. The potential for adults from different regions and genotypes to confer their offspring with higher or lower tolerance to heat and/or sediment was also determined. Gametes were collected and brought to the laboratory for cross fertilization of different genotypes within the regions collected. Larval rearing and settlement were then performed in the laboratory. Newly settled recruits were reared at 29 and 31°C (current summer temperature for August 2017 and +2°C as predicted for 2050) and 4 deposited sediment levels and turbidity (0, 30, 60, and 120mg cm-2, corresponding to 0, 4.52-5.35, 8.16-9.7, and 18.53-19.4 NTU). Recruit survival and growth were measured weekly for 3 months. Increased temperature reduced survival, suggesting faster usage of energy reserves. Regardless of temperature, survival was maximized under 30mg cm-2sediment; the highest sediment level drastically reduced survival. Increasing temperature by 2°C was as deleterious as doubling the natural level of deposited anthropogenic sediment, suggesting that eliminating local stressors may allow recruits to better sustain ocean warming. Growth was not affected by temperature nor sedimentation. Recruits produced by parents from the Florida Keys had a lower initial size but higher growth rate than those from Broward County. None of the parental genotypes conferred their offspring with higher or lower tolerance to warming and/or sedimentation. Reducing turbidity to 4.52-5.35 NTU or less during coastal construction may facilitate the persistence of this species by reducing recruit mortality the first 3 months post-settlement.

Thesis (M.A.)--University of Hawaii at Manoa, 2004. / Includes bibliographical references (leaves 74-82). / xi, 82 leaves, bound ill., maps 29 cm

published_or_final_version / Environmental Management / Master / Master of Science in Environmental Management

Potentially harmful elements (PHEs) have been researched in a wide variety of disciplines, including pedology, chemistry, pollution science and medicine. Within the scientific community, emphasis has usually been placed on the toxic elements, such as cadmium, chromium, lead and arsenic, but rarely has there been consideration of interactions between PHEs, the sediment matrix and processes occurring in the sediments. Dredging of canals is needed for navigability purposes and consequently testing of dredged sediments (to assess whether sediments are hazardous) and landfilling can be costly for British Waterways facing constantly changing regulations and reduction in government grants. PHE mobility and availability in canal sediments can be affected by oxygen availability, pH and Redox. Remediation is thus becoming a priority for British Waterways to limit their operational costs. Zeolites, a type of remediation tool, have been widely studied in the past 30 years due to their attractive properties, such as molecular-sieving, high cation exchange capacities and their affinity for PHEs. The pilot study to investigate the efficiency of the clinoptilolite showed that there was a concentration difference between PHEs adsorbed by the clinoptilolite and the PHE concentration lost from the sediments from three sites in the West Midlands. Thorough characterisation of the sediments was needed to understand the speciation of the PHEs and the secondary processes occurring in the sediments. The different components of the sediments were analysed using various analytical methods, such as X-Ray Fluorescence spectroscopy (XRF), particle size and X-ray Diffraction (XRD) for the solid-inorganic phase, Ion Chromatography (IC) and Inductively Coupled Plasma-Optical Emissions Spectroscopy (ICP-OES) for the liquid phase (pore water), Gas Chromatography-Mass Spectrometry (GC-MS) and organic loss on ignition for the organic phase, pH and Redox for the electrochemistry of the sediments and Scanning Electron Microscope with Energy Dispersive X-Ray analysis (SEM-EDX) for microscopy and imaging. The British Geological Survey (BGS) sequential extraction method was used to investigate the different phases in the sediments. pH remained near neutral for all three sites and Redox remained anoxic. Organic contents for all three sites were around 30% and contained most of the polycyclic aromatic hydrocarbons considered hazardous. Pore water showed only high concentrations of sulphates but low concentrations of PHEs, suggesting PHEs were not mobile. Sequential extraction confirmed the other results showing that PHEs were mainly associated with stable phases, such as iron and manganese oxides or sulphides. The results have been taken into consideration to design a new remediation strategy to maximise efficiency of the zeolite.

The tidal James River, a focus of VCU's Atlantic Sturgeon program, supports both commercial shipping and hydraulic dredging. These anthropogenic threats present documented but preventable sources of mortality to the endangered species. Using three separate VEMCO Positioning System (VPS) receiver arrays, spatial data of previously-tagged fish were collected. ArcGIS and Programita software were used to analyze fish spatial distributions in the presence and absence of potential threats, using additional data including automatic identification system (AIS) vessel locations, vessel passages compiled using camera footage, and dredge records provided by the US Army Corps of Engineers. The data showed a change in distribution associated with vessels that varied according to river width but not vessel type. Dredging was associated with differences in spatial distribution, but more clearly for adults than sub-adults. The responses of Atlantic Sturgeon provide information necessary to propose potential threat mitigations, including seasonal restrictions for both vessels and dredging.

The dredging activity is increasing worldwide due to ships that require bigger drafts, and consequently deeper navigation channels. Some dredging projects requires the operation of cutter suction dredgers on open waters, once these are capable of removing compact sediments and rocks while still maintaining a good productivity. These facts motivated the creation of a weather driven downtime prediction software for this type of operation, based on simplified calculations of the main dredging systems of a CSD. The motions caused by waves, and the forces and moments caused on these dredgers by winds, waves and currents were analyzed in order to evaluate the influence of each parameter magnitude and direction on the behavior of the vessel. The main criteria of the dredger influenced by this conditions were determined by a literature review as being the swing winch required power, the interaction between the cutterhead and the soil, and the anchoring system resistance, this that can be both a spud pole system stress or the Christmas tree cable tension. In this research, only the spud pole system bending stress was considered. Three mathematical models were developed to represent those systems. Since the non-linearity of the relation between the reaction forces of the dredger and the soil was not an object of the study, this process is represented by a constant user defined reaction force and a horizontal cutterhead velocity model. The efficiency of these models were tested by applying them on a case study of the dredging of the Açu port on the Brazilian coast by the Taurus II dredger. Simultaneous wind, wave and current data data were used as input to these models by creating a time series scenario of the operation period. The results for both scenarios showed that the operation would be close to impossible due to wave generated dynamic stress on the spud pole. / A atividade de dragagem no mundo é cada vez mais significativa em função do aumento dos navios que operam em portos, estes que possuem maior calado e requerem, consequentemente, canais de navegação mais profundos. Alguns projetos de dragagem utilizam dragas de sucção e recalque em mar aberto, dada a capacidade destes equipamentos de remover sedimento compactado e rochas, ainda mantendo uma boa produtividade. Estes fatos motivaram a criação de um programa de previsão de downtime gerado por condições ambientais de dragas de sucção e recalque baseado em modelos matemáticos simplificados. Os movimentos causados por ondas, e as forças e momentos causados na draga por ventos, ondas e correntezas foram analisados de forma a se obter a influência da magnitude e direção de cada um destes parâmetros no comportamento da embarcação. Os principais sistemas da draga influenciados por estas condições foram determinados com base em uma revisão bibliográficas como sendo a potência requerida nos guinchos de varredura, a interação do cortador com o solo e a resistência do sistema de ancoragem, sendo este a tensão de flexão dinâmica na trave do spud ou as tensões de ancoragem pelo sistema de árvore de natal. Três modelos matemáticos foram desenvolvidos para representar estes sistemas. Considerando a não linearidade da interação entre a draga e o solo, este processo foi representado por uma força de reação definida pelo usuário e pela velocidade horizontal do cortador. A eficiência destes modelos foi testada ao aplicá-los em um estudo de caso da dragagem do porto de Açu, na costa brasileira pela draga Taurus II. Valores simultâneos de ondas, ventos e correnteza foram utilizadas como entrada nestes modelos, através da criação de um cenário hipotético de série temporal. Os resultados para ambos os casos demonstraram que a operação seria impossibilitada em função de tensões de flexão dinâmicas no spud maiores que o limite determinado.

O crescimento da atividade econômica nacional na movimentação de granéis sólidos e líquidos, bem como na carga geral, vem exigindo o desenvolvimento de uma política especial para o setor de dragagem, de modo a eliminar os passivos existentes nos portos públicos relativos à expansão das atividades portuárias. Dentro desta necessidade de crescimento, as condicionantes ambientais devem ser muito bem avaliadas e integradas aos projetos de dragagem na forma de Estudos de Impactos Ambientais, oferecendo subsídios para o desenvolvimento das atividades e garantindo o controle dos impactos ambientais, através de medidas preventivas, mitigadoras e/ou compensatórias. O presente trabalho avaliou as principais metodologias, equipamentos utilizados e modos de disposição do material dragado nas atividades de dragagens portuárias marítimas, assim como as diferentes variáveis para gestão das operações de escavação e disposição material em função de seus potenciais efeitos sobre o meio ambiente, oferecendo informações que possibilitem a facilitação do processo de decisões nos projetos de dragagem. Para isto, este estudo caracterizou como a gestão ambiental de dragados, com enfoque na disposição de sedimentos em locais confinados, pode influenciar na operacionalidade portuária marítima do ponto de vista técnico, social e econômico, considerando-se as legislações e recomendações vigentes no Brasil e em nível internacional. / The growth of brazilian economic loading rate of bulk solids and liquids, as well as general cargo, requires a special policy for the dredging sector, to remove the existing liabilities in the public ports for the expansion of port activities. Within this growing need, the environmental constraints must be thoroughly evaluated and integrated with dredging projects in the form of Environmental Impact Assesments, offering subsidies for the improvement of activities and ensuring control of environmental impacts through preventive, mitigating and / or allowances. This study evaluated the main methodologies, equipment used and methods of disposal of dredged material from dredging activities in the maritimes ports, and the different variables to manage operations and disposal of excavated material, on the basis of their potential environmental effects, offering information to enable the process of making decisions in dredging projects. With this purpose, the study was characterized as the environmental management of dredged material, focusing how sediments in confined disposal can influence the seaport operation in terms of technical, social and economic development, considering the international and brazilian laws and guidelines, found in Brazil and internationally.

Em decorrência do assoreamento do leito do Rio Paraibuna, no município de Paraibuna/SP, a captação de água para a Estação de Tratamento de Águas (ETA) desse município vem enfrentando problemas com a sucção de areia e outros detritos, fato este que diminui a capacidade de captação e aumenta o desgaste de equipamentos. No presente caso, o problema de assoreamento caracteriza uma situação emergencial em virtude do risco iminente de paralisação das bombas na ETA e, consequentemente, do serviço público essencial de distribuição de água potável para o município. Em 2008, o volume de areia acumulado próximo à área de captação de água era tão elevado que foram formados verdadeiros bancos de areia, prejudicando o abastecimento da cidade, que necessita da captação de 200 litros de água por segundo. Desta forma, fez-se necessário o desenvolvimento do plano de desassoreamento do leito do rio Paraibuna, sendo este avaliado em conjunto com a viabilidade ambiental e econômica da implantação de atividade de explotação de areia como agregado para Construção Civil, na busca de sustentabilidade para tal obra, uma vez que se admite a possibilidade de minimização do impacto ambiental ao desenvolvê-lo em área já degradada. A realização de uma pesquisa mineral mostra-se necessária para viabilização da implantação de um empreendimento minerário, juntamente com a avaliação das técnicas utilizadas no beneficiamento e na lavra aplicados na atividade de explotação de areia no local. Os resultados obtidos nesta pesquisa indicaram que a caracterização granulométrica está situada entre areia média à fina, nas análises por peneiramento. Também foi observado um considerável nível de impurezas orgânicas no sedimento, e nas análises de composição mineralógica, a predominância de quartzo, além de rutilo, muscovita, microclínio, albita e a possível presença de goethita. Por estas análises foi possível concluir que esta areia tem potencial para aproveitamento industrial. / As a result of a silting up of the riverbed of the Paraibuna river, the water capitation for the water treatment plants (WTP) of the city have been facing problems with the sand and other debris suction, fact that diminishes the capitation capacity and increases the equipment consuming. In the present case, the problem characterizes an urgent situation in virtue of the imminent risk of stoppage of the bombs in the WTP and, consequently, of the essential public service of drinking waters distribution for the city. The development of a plan of sand and silt removal in the riverbed of the Paraibuna river has became necessary. In this study it is being evaluated in set with the environmental and economic viability of sand exploitation for construction. A part from the sustainability, it also admits the possibility of reducing the environment impact if developed in area already degraded. The development of a mineral research revealed necessary to make possible the implantation of a mineral enterprise. The results showed that the particle size distribution is situated of a fine to medium sand in the sieving analyses. It was also observed considered level of organic impurities in the sediment and the analyses of mineral composition the quartz predominance beyond rutile, muscovite, microcline, albite and the possible presence of goethite. As a result, it concludes that the sand has a potential and economical evaluation and it can be used in industrial applications.

A Área Portuária do Maranhão, situada na costa ocidental da Ilha de São Luís, na Baía de São Marcos, constitui-se no segundo maior complexo portuário da América Latina e um dos maiores do mundo em termos de movimentação de carga. Esta área portuária abrange o Complexo Portuário de Ponta da Madeira, da CVRD - Companhia Vale do Rio Doce S. A., o Porto de Itaqui, da EMAP - Empresa Maranhense de Administração Portuária e o Porto da ALUMAR, da Alcoa, Alcan, BHPBilliton e Abalco. A caracterização da hidrosedimentologia do Canal de Acesso do Complexo Portuário do Maranhão foi conduzida a partir da compilação e análise dos dados de correntes existentes e da aplicação de modelagem computacional. A caracterização das conformações de fundo foi efetuada a partir da análise de mais de 20 anos de sondagens batimétricas nas áreas de interesse do Canal de Acesso. Com a caracterização da área pretende-se fornecer subsídios à Engenharia Portuária, possibilitando o planejamento de sondagens batimétricas e dragagens de manutenção do Canal. Este trabalho também contempla uma metodologia para fornecimento de previsão de campos de corrente, a partir dos resultados das simulações hidrodinâmicas, e o fornecimento de previsão da evolução e migração das conformações de fundo. A evolução das isóbatas na Área IV mostra que as formações de ondas de areia não evidenciam significativa mudança de posição com o tempo. Em compensação, a Área I, apresenta conformações de fundo com irregularidade da forma de onda, evidenciando que existe uma maior migração destas. O modelo de transporte de sedimentos indicou pequeno transporte resultante nas Áreas IV, III e II, que explica a reduzida migração dessas ondas quando comparadas com a Área I. A determinação das ondas críticas para cada Área constitui-se instrumento na operação portuária, permitindo redução da área hidrografada para definir a tomada de decisão quanto à nova dragagem. / The Maranhão Harbour Area is the second biggest harbour Complex of Latin America and one of biggest of the world in cargo handling is located at the western coast of São Luís Island in São Marcos Bay, this harbour area is composed by the Complex of Ponta da Madeira of CVRD - Companhia Vale do Rio Doce S. A., the Itaqui Harbour, of EMAP - Empresa Maranhense de Administração Portuária and the Alumar Harbour, of Alcoa, Alcan, BHPBilliton and Abalco. The hydrossedimentological characterization of the Access Channel of Maranhão Harbour Area was achieved from current data review and analysis for numerical modeling application. The bottom sand waves description was made from more than 20 years bathymetrical surveys in the interest Areas of the Access Channel. The purpose of this characterization was to improve Harbour Engineering activities, the planning and scheduling of depth surveys campaigns and dredging maintenance. This thesis also provides an approach to get current patterns predictions from the results of the hydrodynamical simulation, and for the prediction of the evolution and the migration of sand waves. The Area IV bottom evolution shows that the sand waves have not significative temporal position shifting. Otherwise, in Area I bed forms have more irregular pattern, showing major wave migration. The sediment transport model pointed to a small sediment transport rate in Area IV, III and II, explaining the smaller migration pattern of these waves when compared with Area I. The critical wave definition in each Area can be an harbour operation tool, reducing the surveyed area needed to take a new dredging maintenance decision.