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Mendes, Renato Paulo dos Santos. "The Douro estuarine plume: detection, processes and dynamics." Doctoral thesis, Universidade de Aveiro, 2016. http://hdl.handle.net/10773/17073.
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Doutoramento em FísicaO Douro é um dos maiores rios da Península Ibérica, constituindo a maior descarga de água doce para o Oceano Atlântico na costa noroeste portuguesa. A sua pluma estuarina tem particular relevância na dinâmica costeira e na modulação de fenómenos biogeoquímicos. São objetivos desta dissertação contribuir para a compreensão dos processos físicos associados à geração e propagação da pluma estuarina do Rio Douro no oceano, assim como para o conhecimento dos seus padrões de dispersão e da forma como estes alteram a hidrologia e a circulação costeira, considerando os agentes forçadores típicos deste fenómeno (caudal fluvial, vento e maré) e índices climáticos relevantes. Para concretização destes objetivos foram desenvolvidas e aplicadas metodologias inovadoras de processamento de dados de deteção remota, assim como novas implementações estuarinas e costeiras de modelos numéricos. Através de imagens MODIS, otimizadas para o estudo de fenómenos costeiros, efetuou-se uma deteção rigorosa da pluma. Identificou-se uma relação entre o sinal túrbido nLw555 e o caudal, demonstrando-se este produto como um bom proxy para a observação da pluma no oceano. As escalas temporais e espaciais da pluma foram caraterizadas através destas imagens, combinadas com dados de caudal fluvial, maré, vento e precipitação, e também com índices climáticos relevantes. Para compreender a propagação da pluma e caracterizar a sua dinâmica e impacto na circulação costeira, foi desenvolvida uma aplicação 3D de modelos estuarinos e costeiros com malhas aninhadas de resolução variável. Definiramse e analisaram-se diferentes cenários de vento e descarga fluvial. A interação da pluma do Rio Douro e do Minho foi ainda analisada através dos resultados de simulações baseadas num evento de inverno. Os compósitos túrbidos mostraram que a pluma é facilmente detetada quando o caudal é maior que 500 m3 s1. A descarga fluvial e o vento são os principais forçadores da sua propagação, enquanto a maré é apenas importante na região próxima à embocadura do estuário. Observaram-se relações a uma escala interanual entre a turbidez da pluma e os índices climáticos East Atlantic e NAO, com uma correlação máxima identificada com 1 e 3 meses de desfasamento, respetivamente. Com base nos resultados das simulações efetuadas, a pluma é classificada como de larga escala e de adveção superficial, apresentando características de uma pluma prototípica. Em condições de caudal moderado a elevado, a descarga estuarina é suficiente para gerar uma corrente costeira para norte sem ação do vento. Em eventos de ventos leste, a propagação da pluma é similar ao caso sem vento, com um aumento da velocidade da corrente. Uma corrente costeira para sul é unicamente identificada sob condições de forte vento de oeste. Ventos de norte tendem a estender a pluma para o largo, com uma inclinação na direção sudoeste, enquanto ventos de sul intensificam a corrente para norte, sendo a mistura das plumas do Douro e do Minho uma consequência possível. A análise desta interação apontou a contribuição do Douro como importante na estabilização da WIBP e nas trocas de água entre o oceano e as Rias Baixas. A interação da pluma do Douro com estuários localizados a sul da sua foz e a confirmação in situ da recirculação observada nos resultados numéricos afiguram-se como temas relevantes para investigações futuras.
The Douro is one of the largest rivers of the Iberian Peninsula, representing the most important freshwater input into the Atlantic Ocean (on the northwestern Portuguese coast). Its estuarine plume has particular relevance on coastal dynamics and biogeochemistry. The main goal of this dissertation is to contribute to increase knowledge on physical processes associated with the generation and propagation of the Douro estuarine plume. The general patterns of dispersion in the ocean and how the plume change hydrography and coastal circulation were also evaluated, considering the typical drivers involved (river discharge, wind and tide) and relevant climate indices. Innovative methodologies to process remote sensing data, as well as new implementations of high-resolution estuarine and coastal numerical models have been developed and applied. The plume was detected through MODIS images, optimized for coastal studies. The relation between the turbid nLw555 signal and river discharge was identified, demonstrating that this product is a good proxy for the observation of the Douro estuarine plume in the coastal ocean. An interconnected approach, combining these images, river discharge, tide, wind and precipitation data, as well as relevant climate indices, was used to study the temporal and spatial scales of the plume. The implementation of estuarine and coastal models with nested domains of variable resolution was developed to understand the plume propagation and characterize its dynamics and impact on coastal circulation. Using these applications, different scenarios of wind and river discharge were defined and analysed. The interaction of the Douro and the Minho estuarine plumes was further evaluated through simulations based on a winter event. Turbid composites showed that the plume is easily detected when river discharge is greater than 500 m3 s1. River discharge and wind are the main driver acting on the plume propagation, whilst tidal effect is only important near the estuary mouth. A relation between turbid plume and climate indices East Atlantic (EA) and North Atlantic Oscillation (NAO) was observed at inter-annual scale, with a maximum correlation identified at 1 and 3-month lags, respectively. The Douro estuarine plume is classified as large-scale and surface-advected, presenting characteristics of a prototypical plume, based on the results of the numerical simulations. The estuarine outflow is sufficient to generate a northward coastal current without wind action under moderate-to-high river discharge conditions. Under easterly winds, the propagation pattern is similar to the case without wind forcing, with a slight increase in the northward current. A southward coastal current is only generated by strong westerly winds. Under upwellingfavourable winds, the plume extends offshore with tilting towards southwest. Southerly winds increase the velocity of the northward current, being the merging of the Douro and Minho estuarine plumes a likely consequence. The analysis of this interaction pointed out the Douro as an important contributor to the WIBP stabilization and in the water exchange between ocean and Rias Baixas. The interaction of the Douro estuarine plume with estuaries located south of its inlet and the in situ confirmation of the re-circulation bulge observed in numerical results seem as relevant for future research topics.
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Al-Enezi, Eqbal Hussain. "Modelling of phosphorus adsorption processes in estuarine and coastal water." Thesis, Cardiff University, 2011. http://orca.cf.ac.uk/54203/.
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This study consists of three parts: (i) Field work and data collection from the Loughor and Severn Estuaries. P adsorption increased with decreasing median sediment size in both estuaries. A positive correlation was found between the P adsorption in sediment and salinity in the Loughor Estuary, whereas a negative correlation was found in the Severn Estuary. Some factors, such as particle grain size, salinity, pH, organic matter, suspended sediment concentration and P concentration were found to control the exchangeable or loosely sorbed P (adsorbed P) in both estuaries. (ii) Laboratory experiments were conducted on P adsorption/desorption on different types on sediment, including Kaolinite, Silica, mud, silt, sand and suspended sediment. P adsorbed to the mud fraction than to the sand fraction. The adsorption coefficient (K d) and Maximum P adsorption (PSMax) for the mud fraction were 0.0091/g and 0.39 mg/g for the silt 0.007 l/g and 0.30 mg/g and the sand 0.001 l/g and 0.05 mg/g. (iii) Flume experiments were conducted in the hydraulic laboratory at Cardiff University, U.K. The main findings revealed that the velocity and the P concentrations in the water were important factors controlling the amount of P adsorbed processes on the sediment. The results from the field work and the laboratory experiments were similar to flume channel findings. These findings were used to develop new source term equations and these equations were added to the QUAL2E water quality model to improve the capability of the model to predict the P adsorption processes in a 2D computer model. These new equations were then used to simulate P concentrations in the estuarine environment using DIVAST.
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Coffey, Michael. "The behaviour of trace metals in the Humber Estuary, U.K." Thesis, University of East Anglia, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.240991.
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Souza, Rogério Riker de. "Modelagem numérica da circulação de correntes de maré na Baía de Marajó e Rio Pará (PA)." Universidade de São Paulo, 2006. http://www.teses.usp.br/teses/disponiveis/3/3147/tde-19092006-154712/.
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A região amazônica possui uma vocação natural para a navegação, uma vez que os rios desempenham um papel preponderante, sendo em muitos casos as únicas alternativas de transporte e comunicação. O trabalho se insere nesse cenário, tendo como objetivo maior a sistematização do conhecimento a respeito da circulação de correntes de maré na Baía de Marajó e Rio Pará (PA), com foco na Área Portuária de Vila do Conde. O melhor entendimento sobre as correntes de maré será um elemento importante para o planejamento portuário e hidroviário interior, além de propiciar um incremento na segurança e otimização nas operações portuárias. A sistematização da circulação das correntes de maré na área de estudo foi implementada através de modelagem numérica com a utilização do software MIKE21 HD de autoria do DHI, consistindo basicamente em um modelo bidimensional verticalmente integrado. Como subsídio à programação numérica, foi realizada uma revisão bibliográfica a respeito dos principais temas relacionados: correntes, maré e vento, bem como foram levantadas as principais bases de dados da região, utilizados na calibração e validação do modelo numérico. Em razão da escassez de dados disponíveis a calibração foi executada com dados do Porto de Vila do Conde, por meio de medições de intensidade e direção das velocidades das correntes nos anos de 1991 e 2001. A validação foi realizada através da Carta de Correntes de Maré, com ponto específico na Baía de Marajó. O programa mostrou-se consistente e aplicável à realidade, permitindo desta forma a obtenção de Cartas de Correntes de Maré para toda a área de estudo, bem como para a área foco.In the amazonic region, navigation is the natural and leading, in some cases the only one possibility, role in the transportation network. In this scenario, the thesis has the main purpose of consolidating the knowledge about tidal currents pattern in Marajó Bay and Pará River (PA), considering Vila do Conde Harbour as the most important study area. A best knowledge about the tidal currents will be an important factor for port and waterway planning, contributing to increase the port operation safety and development. The tidal currents pattern was consolidated through numerical modelling using DHI MIKE 21 HD software, which is a bidimensional vertically integrated model. A bibliographical review was carried out about correlated themes: currents, tides and winds, and also was made a data base research, which was used in the numerical model calibration and validation. Due to the few data obtained, calibration was performed with Vila do Conde Harbour data, using current intensity and directions obtained in 1991 and 2001 surveys. The validation was performed using the Tidal Currents Chart, for a point in the Marajó Bay. The software results showed a consistent fit to the real condition, which made possible to get a Tidal Currents Chart of the whole area and for the focus area.
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Dyson, Kirstie Elizabeth. "Biodiversity and ecosystem processes in heterogeneous environments /." St Andrews, 2008. http://hdl.handle.net/10023/698.
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Kenny, Carolyn. "Nitrogen transformation processes and nitrous oxide evolution in estuarine intertidal zones." Thesis, Royal Holloway, University of London, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.417365.
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Smar, Daina. "An assessment of ecological processes in the Apalachicola estuarine system, Florida." Master's thesis, University of Central Florida, 2012. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/5506.
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The following is a compilation of field data collected in 2011 and 2012 in Apalachicola, FL as part of a five year study assessing the ecological effects of sea level rise in the northern Gulf of Mexico. Many coastal communities, both natural and developed, will soon be working to mitigate the effects of sea level rise, if they are not already doing so. This thesis investigates the natural patterns of the Apalachicola estuarine system through the collection and analysis of in situ water, sediment, and biomass samples. Additionally, results of the field samples are presented and recommendations for additional sampling are given. The field methods and procedures developed in this study were designed to be repeated in other estuaries to build upon the work that has been conducted in Apalachicola. Water samples were tested for total suspended solids (TSS) and compared against hydrodynamic (tidal circulation and streamflow) and meteorological (wind and precipitation) characteristics. Streamflow was determined to influence a seasonal base level concentration of TSS. Wind strength and direction consistently influenced small TSS concentration fluctuations, an effect amplified by the shallow nature of the estuary. Tidal circulation appeared to have minor influences on TSS concentration fluctuations within the base level concentration range. Precipitation appeared to influence large TSS concentration fluctuations; however, due to limited data collection during storm events, more data is required to conclusively state this. Sediment cores throughout the lower Apalachicola River revealed that coarse particles settled out in upstream areas while fine particles tended to stay in suspension until low energy areas in the lower portions of the river or marsh system were reached. Finally, biomass samples were used to develop regression models utilizing remotely sensed data to predict biomass density in marsh areas with unprecedented accuracy. The documented patterns of this system are to be used as inputs and validation points to update an existing hydrodynamic model and to aid in the coupling and development of sediment transport and marsh equilibrium models. The field campaign developed and implemented here provides a foundation for this novel coupled modeling effort of estuarine systems. From the 2011 and 2012 sampling conducted, it is apparent that Apalachicola can be modeled as a closed system with river inflow and sediment influx as boundary conditions. Forcing local conditions should accurately represent the system. Ultimately, these models will be used to simulate future sea level rise scenarios and will provide useful decision making tools to coastal managers. Future work will include replicating water sampling in subsequent wet and dry seasons in Apalachicola, FL to confirm observed trends, in addition to implementing this sampling in Grand Bay, MS and Weeks Bay, AL. Additional biomass samples will be taken to validate the strong correlations found between remotely sensed data and in situ samples. In similar studies, it is recommended that water samples be taken to adequately represent influences from tidal cycles and riverine inflow. It is also recommended that spatially distributed biomass samples be taken to validate regression models.M.S.
Masters
Civil, Environmental, and Construction Engineering
Engineering and Computer Science
Civil Engineering; Water Resources Engineering
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Yannaccone, John A. "Numerical simulation of the effects of sea level rise on estuarine processes." Thesis, Virginia Polytechnic Institute and State University, 1987. http://hdl.handle.net/10919/50072.
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The increasing concentration of carbon monoxide and other gases in the earth’s atmosphere is expected to cause temperatures on earth to increase. This condition, known as the greenhouse effect, could cause the sea level to rise due to the partial melting of the polar icecaps and the thermal expansion of the oceans. Such a rise in the sea level would affect the tides, currents, and sediment and salinity distributions within estuaries.
To see the nature of these effects, a parametric study was performed on the Rappahannock River in Virginia with a two-dimensional, laterally averaged, time-dependent numerical model which simulates the movement of water and suspended sediment in the estuary. The model is a systematic sequence of mathematical procedures derived from the mass-balance equation and the equation of motion. These equations are solved through an explicit finite difference scheme.
The astronomical tide, the increased height of the sea level due to the greenhouse effect and the additional tidal height due to a storm surge form the boundary conditions at the mouth of the river. Freshwater streamflows constitute the boundary condition at the upstream end of the estuary. A frequency analysis is performed for both the freshwater streamflows and the tidal heights. A procedure is developed which allows one to calculate the return period for various combinations of streamflow and tidal height.
The results from each run of the estuary model are reviewed to study the tidal hydraulics and the longitudinal and vertical distributions of the sediment and salinity with and without the sea level rise.Master of Science
incomplete_metadata
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Budi, Santoso Eko. "Tidal anomalies at river entrances and the physical processes which generate them /." St. Lucia, Qld, 2004. http://www.library.uq.edu.au/pdfserve.php?image=thesisabs/absthe17707.pdf.
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Gomes, Filho Jose Gerardo Ferreira. "Pre- and post-settlement processes influencing the distribution of barnacles along estuarine gradients." Thesis, University of Plymouth, 2007. http://hdl.handle.net/10026.1/2409.
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Estuaries are the interface between freshwater systems and the sea, with clearly recognizable changes in the distribution of organisms along various environmental gradients from riverine to fully marine conditions. This thesis studied ecological processes affecting the distribution of marine species along estuarine gradients using both field and laboratory experiments with barnacles as a tractable model system. Elminius modestus Darwin, Semibalanus balanoides Linneaus, Chthamalus montagui Southward are the most common barnacle species found in the intertidal of British estuaries. Surveys performed in the Plym and the Yealm Estuaries revealed that E. modestus occurred furthest up estuaries and was dominant along most of their length, with the exception of sites closest to the sea; C. montagui had the most restricted degree of penetration up-estuary; and S. balanoides occurred at low abundances, with limits of penetration located between those of C. montagui and E. modestus. Transplants of adult specimens to sites along the marine-to-freshwater gradient revealed that E. modestus was better adapted to environmental conditions found in inner areas of the estuaries than C. montagui and S. balanoides. Survival of the latter two species was negatively correlated with deposition of silt and decreasing salinity. Laboratory experiments showed that, in contrast to the other two species, E. modestus was highly tolerant to burial by silt. A comparison of observed distributions along the gradients with survivability showed that C. montagui was able to survive in areas where adults were absent, indicating that early life cycle stages were a potential limiting factor to the distribution of this species. Examination of patterns of cyprid settlement and recruitment to the benthic phase reinforced the suggestion that pre-settlement processes contribute to restrictions in the distribution of both C. montagui and S. balanoides. The abundance of these species, post-settlement, was also affected by physico-chemical conditions in the upper estuary. Pre-settlement processes did not limit the distribution of E. modestus and post-settlement processes appeared to be more important in limiting its abundance at sites closest to the sea.
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Weaver, Andrew John. "Numerical and analytical modelling of oceanic/atmospheric processes." Thesis, University of British Columbia, 1987. http://hdl.handle.net/2429/27560.
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Two problems in oceanic/atmospheric modelling are examined in this thesis. In the first problem the release of fresh water from a midlatitude estuary to the continental shelf is modelled numerically as a Rossby adjustment problem using a primitive equation model. As the initial salinity front is relaxed, a first baroclinic mode Kelvin wave propagates into the estuary, while along the continental shelf, the disturbance travels in the direction of coastally trapped waves but with a relatively slow propagation speed. When a submarine canyon extends offshore from the estuary, the joint effect of baroclinicity and bottom relief provides forcing for barotropic flow. The disturbance now propagates along the shelf at the first coastally trapped wave mode phase speed, and the shelf circulation is significantly more energetic and barotropic than in the case without the canyon. For both the experiments with and without a canyon an anticyclonic circulation is formed off the mouth of the estuary, generated by the surface outflow and deeper inflow over changing bottom topography. As the deeper inflow encounters shallower depth, the column of fluid is vertically compressed, thereby spinning up anticyclonically due to the conservation of potential vorticity. This feature is in qualitative agreement with the Tully eddy observed off Juan de Fuca Strait. A study of the reverse estuary (where the estuarine water is denser than the oceanic water) shows that this configuration has more potential energy available for conversion to kinetic energy than the normal estuary. Bass Strait may be considered as a possible reverse estuary source for the generation of coastally trapped waves. Model solutions are compared with field observations in the Bass Strait region and with the results of the Australian Coastal Experiment. The effects of a wider shelf and a wider estuary are examined by two more experiments. For the wider shelf, the resulting baroclinic flow is similar to that of the other runs, although the barotropic flow is weaker. The wide estuary model proves to be the most dynamic of all, with the intensified anticyclonic circulation now extending well into the estuary.
In the second problem the effect of the horizontal structure of midlatitude oceanic heating on the stationary atmospheric response is examined by means of a continuously stratified model and a simple two level model, both in the quasigeostrophic β-plane approximation.
Solutions are obtained for three non-periodic zonal heating structures (line source, segmented cosine, and segmented sine). Little difference is observed between the solutions for these two different models (continuously stratified and two level). There are two cases which emerge in obtaining analytic solutions. In case 1, for large meridional wavenumbers, there exists a large local response and a constant downstream response. In case 2, for small meridional wavenumbers, the far field response is now sinusoidal. A critical wavenumber separating these two cases is obtained. The effect of oceanic heating on the atmosphere over the Kuroshio region is examined in an attempt to explain the large correlations observed between winter Kuroshio oceanic heat flux anomalies, and the winter atmospheric surface pressure and 500 & 700 mb geopotential heights, both upstream and downstream of the heating region. In both models, the response is consistent with the observed
correlations. When western North Pacific heating and eastern North Pacific cooling are introduced into the models, a large low pressure response is observed over the central North Pacific. This feature is in excellent agreement with the observed correlations. A time dependent, periodic, two level model (with and without surface friction) is also introduced
in order to study the transient atmospheric response to oceanic heating. The height at which the thermodynamic equation is applied is found to be crucial in determining the response of this model. When the heating is entered into the model near to the surface, unstable modes are prevalent sooner than they would be when the heat forcing is applied at a higher level. As in the steady state models, two cases dependent on the meridional wavenumber ɭ emerge in the analysis. For small scale meridional heating structures (large ɭ), the response consists of an upper level high and a lower level low which propagate eastward with time. For large scale meridional heating structures (small ɭ) the response essentially consists of a wavenumber 3-4 perturbation superimposed on the solution for large ɭ.Science, Faculty of
Mathematics, Department of
Graduate
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Gao, Guanghai. "Numerical modelling of hydrodynamic and sediment-bacteria interaction processes in estuarine and coastal waters." Thesis, Cardiff University, 2008. http://orca.cf.ac.uk/54738/.
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A study has been undertaken to investigate and improve the representation and modelling of a range of various hydrodynamic, biochemical and sediment transport processes relating to the transport of enteric bacteria organisms in estuarine waters. In this study a relatively simple turbulence model was first further investigated to predict the complex three-dimensional flow structure in a flume with vegetation. The main purpose of this part of the study was to try and acquire accurate velocity profiles of complex flows without the need for a more advanced two-equation turbulence model, requiring values for a number of unknown coefficients and extra computing cost. The results showed that the simple two layer mixing length model was capable of giving more accurate complex velocity profile predictions, with the advantage of requiring limited coefficient data. Formulations developed through earlier studies for dynamic decay rates were then refined and included in the numerical model. The model predictions were tested against field data, with good agreement being obtained. Further refinements to the representation of the transport of bacteria through the flow field were included in the model by the novel addition of the interaction of bacteria with the sediments by partitioning the total bacteria into their free-living and attached phases using a dynamic partitioning ratio. This ratio was related to the suspended sediment concentrations. The novel method used in this study was to include the re-suspension and deposition of the absorbed bacteria with the sediments and this approach has been tested against analytical solutions for steady uniform flow conditions, and published field and experimental data. The model was then applied to the Severn Estuary. After calibration against available data sets the model was then run for different scenarios to investigate the effects of different hydro-environmental conditions on the bacteria distributions in the Severn Estuary. The model was finally used to investigate the impact of the proposed Cardiff-Weston tidal barrage on the hydrodynamic, the sediment transport and bacterial processes within the Severn Estuary. The results showed that the barrage would reduce the currents, as well as significantly reducing the suspended sediment concentrations and bacteria concentration levels in the estuary.
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Geronilla, Kristina. "Re-presenting the Waterfront: revealing the intersection of human and natural processes." Thesis, Virginia Tech, 2004. http://hdl.handle.net/10919/35894.
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Water and waterfronts are appealing to almost any person, as a visitor or designer. This study challenges the author's design processes and understanding of the landscape as the sculpted meeting ground, intersecting human and natural physical processes. It progresses from assumptions through collaborated ideas of others in a literature review through case studies of various waterfront situations and finally to the design project of the Jones Point waterfront in Alexandria, Virginia. Here the intermingled aspects from cultural activities over time and local, physical movement of land by water are assessed to be revealed and enhanced for the visitor's benefit, use, and connection with place. For it is the author's belief that the landscape and space can be sculpted, experienced, and imagined for the purpose of connecting us to a larger framework of living systems on this planet and beyond. The design extends the city to the waterfront and vice versa with an understanding of both physical processes and cultural choices to the point of being unable to distinguish action from reaction.Master of Landscape Architecture
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Cahyono, M. "Three-dimensional numerical modelling of sediment transport processes in non-stratified estuarine and coastal waters." Thesis, University of Bradford, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.520623.
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Details are given herein of the development, refinement and application of a higher-order accurate 3-D finite difference model for non-cohesive suspended sediment transport processes, in non-stratified estuarine and coastal waters. The velocity fields are computed using a 2-D horizontal depth-integrated model, in combination with either an assumed logarithmic velocity profile or a velocity profile obtained from field data. Also, for convenience in handling variable bed topographies and for better vertical resolution, a δ-stretching co-ordinate system has been used. In order to gain insight into the relative merits of various numerical schemes for modelling the convection of high concentration gradients, in terms of both accuracy and efficiency, thirty six existing finite difference schemes and two splitting techniques have been reviewed and compared by applying them to the following cases: i) 1-D and 2-D pure convection, ii) 1-D and 2-D convection and diffusion, and iii) 1-D non-linear Burger's equation. Modifications to some of the considered schemes have also been proposed, together with two new higher-order accurate finite difference schemes for modelling the convection of high concentration gradients. The schemes were derived using a piecewise cubic interpolation and an universal limiter (proposed scheme 1) or a modified form of the TVD filter (proposed scheme 2). The schemes have been tested for: i) 1-D and 2-D pure convection, and ii) 2-D convection and diffusion problems. The schemes have produced accurate, oscillation-free and non-clipped solutions, comparable with the ULTIMATE fifth- and sixth-order schemes. However, the proposed schemes need only three (proposed scheme 1) or five cell stencils. Hence, they are very attractive and can be easily implemented to solve convection dominated problems for complex bathymetries with flooding and drying. The 3-D sediment transport equation was solved using a splitting technique, with two different techniques being considered. With this technique the 3-D convective-diffusion equation for suspended sediment fluxes was split into consecutive 1-D convection, diffusion and convective-diffusion equations. The modified and proposed higher-order accurate finite difference schemes mentioned above were then used to solve the consecutive 1-D equations. The model has been calibrated and verified by applying it to predict the development of suspended sediment concentration profiles under non-equilibrium conditions in three test flumes. The results of numerical predictions were compared with existing analytical solutions and experimental data. The numerical results were in excellent agreement with the analytical solutions and were in reasonable agreement with the experimental data. Finally, the model has also been applied to predict sediment concentration and velocity profiles in the Humber Estuary, UK. Reasonable agreement was obtained between the model predictions and the corresponding field measurements, particularly when considered in the light of usual sediment transport predictions. The model is therefore thought to be a potentially useful tool for hydraulic engineers involved in practical case studies
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Pidduck, Emma Louise. "The importance of micro-scale processes on the release of macro-nutrients from estuarine suspended sediments." Thesis, University of Plymouth, 2016. http://hdl.handle.net/10026.1/5378.
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The quality of water within an estuary is inseparable from the component parts; suspended particulate matter (SPM) and the balance of macro-nutrients. Long-term temporal variations and the horizontal advection of both SPM and macro-nutrient concentrations are well-constrained, but the vertical fluxes associated with micro-scale processes, such as turbulence and flocculation, are poorly constrained. The importance of three micro-scale processes on the interactions between SPM and inorganic macro-nutrients, nitrate (NO–3 ), ammonium (NH+4) and phosphate (PO3 –4 ), are examined in four field campaigns and five laboratory experiments. Field campaigns were conducted in two turbid estuaries. One field campaign was conducted in the Seine estuary, France, and three campaigns in the Tamar estuary, U.K., in order to consider the effects of seasonal variations (spring, summer and autumn). Physical conditions measured included current velocity, turbidity, turbulence and particle size, were recorded using a suite of oceanographic instrumentation. Five different laboratory studies were conducted using the same mini annular flume, with different background conditions. Inorganic macro-nutrients were measured spectrophotometrically on a continuous flow analyser (for NO – 3 and PO3 –4) and fluorimetry (NH +4). Three hypotheses are presented as potential mechanisms controlling the release and uptake of macro-nutrients from sediments. Mechanism One (M1) described an exchange process between inorganic macro-nutrients and flocculation/disaggregating particles. It was hypothesised that flocculating particles would decrease water column macro-nutrient concentrations, and vice versa. In this study, flocculation was observed in both field sites, but there was no significant relationship between flocculation and macro-nutrient concentration. Similarly, the five laboratory studies demonstrated no statistically significant relationships between flocculation and macro-nutrient concentrations. Mechanism Two (M2) hypothesised that turbulence would enhance the release portion of the exchange processes described in M1. Furthermore, it was proposed that increased turbulence would break bonds between macro-nutrients and the surface of particle faces. Turbulence was observed to limit the floc size in all experiments (both field and laboratory), but this study determined that it did not promote a significant release mechanism for inorganic macro-nutrients. However, this study observed that turbulence played a key role in the vertical distribution of PO 3 – 4 and NH +4. In both the Seine and Tamar estuaries, surface and near-bed concentrations were observed to be statistically significantly different (p = < 0.05). Finally, Mechanism Three (M3) hypothesised that increased salinity provides additional salt water cations that would enhance flocculation and M1. This study measured an increase in floc size with increasing salinity in but did not enhance the proposed M1. Instead, as with turbulence, differences in water density as a result of the salinity affected the vertical distribution of NO –3. This research concluded that micro-scale processes have no significant impact on the water-column concentration of inorganic macronutrients. Instead, it was observed that two of the three micro-scale processes, turbulence and salinity, play a key role in the vertical distribution of inorganic macro-nutrients in the Tamar and Seine estuaries.
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Vinson, Joshua S. "Role of oxygen and salinity on biogeochemical processes controlling mercury and monomethylmercury flux from estuarine sediments." View electronic thesis, 2008. http://dl.uncw.edu/etd/2008-2/r1/vinsonj/joshuavinson.pdf.
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Josko, Troselj. "FLUVIAL INFLUENCE ON ESTUARINE SEDIMENT TRANSPORT PROCESSES AND LINKAGE OF ITS OUTFLOW DATA TO COASTAL MODELING." Kyoto University, 2016. http://hdl.handle.net/2433/217745.
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Marvan, Fernando G. "A two-dimensional numerical transport model for organic-rich cohesive sediments in estuarine waters." Thesis, Heriot-Watt University, 2001. http://hdl.handle.net/10399/1212.
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Enot, Patricia. "Physical and geochemical processes affecting fate of low-pH leachate and associated metal contaminants in an estuarine aquifer." Thesis, University of Edinburgh, 2005. http://hdl.handle.net/1842/13801.
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The aim of the study was to carry out a much needed field investigation on the physical and chemical processes affecting contaminant movement in the groundwater of coastal aquifers, prior to their discharge to coastal waters. The study site located in Ayrshire, UK, was selected as it contains a low-pH acidic and metal-contaminated plume migrating to the Garnock estuary. The tidal estuary is characterised by a very low relief sandy beach. A key research motivation was to determine the mechanisms of contaminant attenuation on the transport pathway, which significantly reduced the impact of groundwater contamination on the estuary. It was found that near to the shore, the groundwater flow was very responsible to changes in the tidal stage. The amplitude of the tidally induced water table fluctuations was rapidly dampened as it propagated inland due to the mild sloping beach. A zone of brackish groundwater of marine origin was found at depth and identified as part of the saltwater intrusion wedge. Little spatial and temporal changes observed during the monitoring period suggest that the saline water was at a quasi-steady state. Mixing between upper acidic and deep alkaline saline groundwaters was unlikely in the monitoring transect. The migration of the acidic plume towards the estuary was limited to the upper section of the aquifer, and was considerably affected by buffering processes involving mainly carbonates, AI and Fe oxy-hydroxides. In turn, the fate of metal contaminants was mainly controlled by pH, however the effect of sediment heterogeneity on the distribution of dissolved metals was shown to be significant. In addition, the results suggested that tide-induced fluctuations in the groundwater flow would have an impact on the distribution of metal contaminants near the shore.
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Schindler, Jennifer. "Estuarine Dynamics as a Function of Barrier Island Transgression and Wetland Loss: Understanding the Transport and Exchange Processes." ScholarWorks@UNO, 2010. http://scholarworks.uno.edu/td/1260.
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The Northern Gulf of Mexico and coastal Louisiana are experiencing accelerated relative sea level rise rates; therefore, the region is ideal for modeling the global affects of sea level rise (SLR) on estuarine dynamics in a transgressive barrier island setting. The field methods and numerical modeling in this study show that as barrier islands are converted to inner shoals, tidal exchange increases between the estuary and coastal ocean. If marshes are unable to accrete at a pace comparable to SLR, wetlands will deteriorate and the tidal exchange and tidal prism will further increase. Secondary to hurricanes, winter storms are a primary driver in coastal morphology in this region, and this study shows that wind direction and magnitude, as well as atmospheric pressure change greatly affect estuarine exchange. Significant wetland loss and winter storm events produce changes in local and regional circulation patterns, thereby affecting the hydrodynamic exchange and resulting transport.
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Shi, Jie. "Integrated modelling of hydrological and hydrodynamic processes, dynamic bacteria decay with climate change and intensive farming in riverine and estuarine water." Thesis, Cardiff University, 2016. http://orca.cf.ac.uk/98617/.
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The water quality deteriorations in river and estuarine waters are a global issue. Particularly, the water quality impairment due to contamination of Faecal Bacteria Indicator, such as E. coli and Faecal Coliform in river channel, estuary bathing and shellfish waters are of special interests due to potential risks to human health. These indicators are important in water quality assessment outlined in both EU Water Framework Directive and US Clear Water Act. The hypothesis of the study is that the global climate change and intensive farming would cause severe deterioration to faecal coliform levels in these water bodies. Approaches to quantify these impacts are carried out with numerically modelling through catchment model Soil and Water Assessment Tool (SWAT) and hydrodynamic model DIVAST with the focus in the coastal catchment of river Frome and Piddle connected to a natural harbour in Dorset, southern England.
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Rubio, Zuazo Ana Maria, and anarubio zuazo@gmail com. "Environmental influences on the sustainable production of the Sydney rock oyster Saccostrea glomerata : a study in two southeastern Australian estuaries." The Australian National University. Centre for Resource and Environmental Studies, 2008. http://thesis.anu.edu.au./public/adt-ANU20080618.091057.
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There has been a continuous decline in both the production and general performance of the
SRO in NSW estuaries over the past three decades. The relationship of this decline to both
environmental and oyster-density related factors are assessed in this thesis. This question has
been examined at different scales: a large scale that compares two different estuaries (Clyde and
Shoalhaven Rivers, southern NSW); a regional scale that encompasses variations within an
estuary and, at a lease scale that examines processes pertaining to individual or small groups of
oysters. Levels of inorganic nutrients were in general very low potentially limiting primary
production. The limiting nutrient was nitrogen or phosphorus depending on whether long term
conditions were dry or wet, respectively. Only during rain events, through the input of terrestrial
material, were conditions favourable for fast rates of primary production. Carbon and nitrogen
isotope analysis has demonstrated that both external material and local resuspension of the
benthos constitute a major proportion of the SRO diet. The uptake of the various food sources
also varied considerably depending on local environmental conditions. Increases in SRO growth
were strongly correlated to increases in temperature with a low temperature cut-off at ~13°C.
Growth also appeared to reduce considerably when salinities lower than ~15ppt persisted for the
order of a month. These factors may alter growth through changes in filtration rates. These
processes were modelled in a coupled hydrodynamic-NPO (Nitrogen-Phytoplankton-Oyster)
model of the Clyde River. This demonstrated that primary production was more affected by
estuarine dynamics and nutrient concentrations than oyster uptake. At the current levels of
oyster densities, primary production by itself could not account for the observed oyster growth,
however growth became realistic with observed levels of POC added to the model. A set of
environmental indices were used to complement the model and to assess the sustainability of the
culture system. The combined indices indicated that while the ecological carrying capacity of
the Clyde was exceeded the production capacity at an estuarine scale was not. On the lease
scale, density experiments showed that while growth was not reduced as a result of current
stocking densities, the condition index was significantly affected.
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Mfikili, Athi Nkosibonile. "Influence of sedimentological and hydrological processes on the distribution of the Spartina maritima salt marsh in the Keurbooms Estuary, Western Cape." Thesis, Nelson Mandela Metropolitan University, 2017. http://hdl.handle.net/10948/13004.
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Salt marshes are some of the most productive ecosystems in the world and have been the centre of attention over the past few decades, due to their decline as a result of global climate change and anthropogenic impacts. The growth of salt marshes is determined by substrate type, soil conductivity and elevation. The permanently open Keurbooms Estuary along the south-east coast of South Africa is subjected to occasional fluvial flooding and its intertidal area lacks well developed salt marshes, with Spartina maritima restricted to the lower reaches of the Bitou tributary and a few sections of the Keurbooms tributary. Presumeably because of fine sediment habitat in the confluence and lower Bitou tributary. The salinity of the estuarine water ranges between 0.1 – 26.9 and 3.2 – 35.3 in the Bitou and Keurbooms tributaries respectively. A typical salt wedge salinity pattern is common in the Keurbooms tributary where saline water often intrudes underneath the freshwater, especially during high river flows. The following hypotheses were developed and tested in this study: The limited spatial distribution of S. maritima in the Keurbooms Estuary is due to limited availability of fine sediment habitat; and the source of the fine sediment in the estuary is the Bitou tributary rather than the Keurbooms tributary or the sea. It was further postulated that after sediment characteristics, floods are the major hydrological driver determining the distribution of S. maritima in the Keurbooms Estuary. The results of the surveys of the estuarine channel bottom sediments showed that the Keurbooms tributary was mostly characterized by the sand-size sediment fraction derived from the feldspathic and sandstone with evidence of fine sediment fractions restricted to the upper reaches at the confluence with Whiskey Creek. The Bitou was almost always composed of coarse sized sediments in the upper reaches, fine sediment deposits in the middle and lower reaches and medium sorted sand with almost no clay or calcium carbonate in the estuarine component below the confluence of the tributaries. These findings were further supported by the surface sediment deposited within the S. maritima intertidal salt marsh, which showed finer sediment deposits in the Bitou marsh compared to the Keurbooms marsh surface. Similar results were also found in the sediment cores, with the Keurbooms marsh sediment becoming finer with increasing depth whereas fine sediments reduced with depth in the Bitou marsh. The results of the sediment mineralogy indicated that the increased concentrations of clay minerals in the S. maritima surface sediments are derived from the Bokkeveld shale, siltstone and clay slate exposed above the N2 Bridge in the Keurbooms Estuary. GIS mapping shows that S. maritima has been declining over the past two decades, with rapid decreases especially evident after big flooding events. The GIS mapping also indicates that the patches of the S. maritima in the Keurbooms tributary are more exposed to big floods than the Bitou marsh. Despite showing an overall decline, S. maritima area coverage remained more consistent in the lower reaches of the Bitou tributary than in the Keurbooms tributary. Despite the larger and more persistent area cover, the S. maritima plants were shorter and less dense than the plants growing in the sandy substrate. The black/grey colouration of soil with increasing depth in the Bitou tributary was an indication of the reduced state of the soil caused by prolonged waterlogged conditions. The roots of S. maritima in both tributaries were mostly restricted to the sub-surface substrate layer (i.e. 0 – 0.25 m), although the Bitou populations showed more vegetative propagation than the Keurbooms populations. This mechanism of reproduction was also demonstrated during the transplant experiment which showed a greater number of new stem production in the fine sediment substrates compared to the sandy silt substrates. Although accretion rates were not determined in this study, the short-term sediment deposition rates revealed that sedimentation is active in the marshes of the Keurbooms Estuary. Therefore, in spite of showing a decline in area cover, the production of viable seed and observed vegetative propagation suggest that the S. maritima is likely to colonize open stable intertidal mudflats / sandflats, thus maintaining its distribution as an intertidal species in the salt marshes of the Keurbooms Estuary.
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Navera, Umme Kulsum. "Development of a model for predicting wave-current interactions and sediment transport processes in nearshore coastal waters." Thesis, Cardiff University, 2004. http://orca.cf.ac.uk/55916/.
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A two-dimensional numerical model has been developed to simulate wave-current induced nearshore circulation patterns in beaches and surf zones. The wave model is based on the parabolic wave equation for mild slope beaches. The parabolic equation method has been chosen because it is a viable means of predicting the characteristics of surface waves in slowly varying domains and in its present form dissipation and wave breaking are also included. The two dimensional parabolic mild slope equation was discretised and solved in a fully implicit manner, so stability did not create a major problem. This wave model was then embedded into the existing numerical model DIVAST. The sediment transport formulae from Van Rijn was used to calculate the nearshore sediment transport rate.
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Harbison, John Edwin. "Groundwater chemistry and hydrological processes within a Quaternary coastal plain: Pimpama, Southeast Queensland." Thesis, Queensland University of Technology, 2007. https://eprints.qut.edu.au/16647/1/John%20Harbison%20Thesis.pdf.
Full textAbstract:
The Pimpama estuarine plain in subtropical southeast Queensland is comprised of Quaternary sediments infilling older bedrock. These multilayered unconsolidated sediments have various depositional origins, and are highly heterogeneous. The plain is low-lying and the surface drainage is controlled by flood mitigation measures including tidal gates and channelised streams. The control of surface drainage potentially affects the shallow water table. This modification of hydrology has implications for future viability of agriculture and also the environmental health of waterways. Increased landscape modification and water management is likely in the coming years. The combination of sediment heterogeneity, low hydraulic gradients, and artificial drainage modification result in the plain being hydrogeologically complex. In order to understand hydrologic processes in this setting, a multi-disciplinary research programme was conducted which included a drilling program, overland electromagnetic induction and other geophysical surveys (downhole gamma log, electromagnetic induction and magnetic susceptibility) to initially establish the geologic framework. These surveys were followed by hydrogeochemical testing which includes for major and minor ions and also stable isotopes, and mineralogical analysis of drillhole material. Underlying basement rock occurs at up to 60 m depth. Unconsolidated gravel and sand deposits occur within incised paleo-valleys and are overlain by predominantly low-permeability fluvial sandy clays and estuarine and lagoonal muds. Fine-grained delta sands occur in the top 15 m of the sub-surface. Within the unconsolidated sediments, hydrodynamic trends clearly discriminated between upper unconfined and lower semi-confined aquifer systems. A comparison of surface water and shallow groundwater levels indicate limited interaction of groundwater and surface water. Hydrogeochemical analysis effectively distinguished between groundwater bodies, and also distinguished saline groundwater from seawater. Trends in major ion chemistry in the semi-confined system (particularly Na/Cl and Ca/Cl ratios) showed ion exchange accompanying saline intrusion. However, due to factors such as mineral dissolution, major ion chemistry does not clearly identify solute flux trends in the shallow aquifer system. Water stable isotope analysis (δ18O and δ2H) indicated the provenance of fresh and saline groundwater and also the relative importance of the principal hydrologic processes, i.e. evaporation and water uptake by plants. Groundwater exhibited a wide range in salinity, from very fresh to hypersaline. The formation of hypersaline groundwater was attributed largely to uptake of water by mangrove forests. Since mangrove forests were more extensive at the time of the Holocene maximum sea level (approximately 6,000 years ago) than at present, some of this groundwater may represent relict salinity from this earlier time. The relationship of relict salinity to low permeability sediments, particularly at intermediate depths, and their depositional history was examined. Vertical salinity gradients and hydrogeochemistry within these sediments varied according to position within the plain, suggesting deposition under various hydrological and sea level regimes. A preliminary investigation using analysis of stable sulfate isotopes (δ34S and δ18OSO4) was made. This study shows substantial potential for the application of this technique for quantification of solute flux and sulfur chemical transformations within settings such as this coastal plain. To establish shallow groundwater flow processes, a MODFLOW-based numerical model was used to inversely estimate aquifer parameters under various recharge scenarios. The model was designed to examine the relative importance of evapotranspiration and discharge to surface waters. However, largely due to the complexity of the drainage network and non-uniform surface water flows, the quantification of surface water- groundwater interaction by consideration of hydrodynamics is problematic. Therefore, the chemistry of groundwater and surface water was compared. While the estimated contribution of rainfall to groundwater level fluctuations was significant (46%), high evapotranspiration rates reduced net recharge and it was concluded that baseflow to drains and creeks during dry periods was insignificant, and groundwater velocities in the shallow aquifer are low. The study illustrates the value of both hydrodynamic and hydrogeochemical analyses in estuarine settings where relict salinity and groundwater-aquifer interactions impact significantly on water quality. Saline groundwater is chemically distinct from theoretical mixtures of seawater and freshwater. The study also demonstrates the value of particular chemical parameters, e.g. Na/Cl and SO4/Cl ratios and stable water isotopes, for identifying hydrologic processes in this setting.
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Harbison, John Edwin. "Groundwater chemistry and hydrological processes within a Quaternary coastal plain: Pimpama, Southeast Queensland." Queensland University of Technology, 2007. http://eprints.qut.edu.au/16647/.
Full textAbstract:
The Pimpama estuarine plain in subtropical southeast Queensland is comprised of Quaternary sediments infilling older bedrock. These multilayered unconsolidated sediments have various depositional origins, and are highly heterogeneous. The plain is low-lying and the surface drainage is controlled by flood mitigation measures including tidal gates and channelised streams. The control of surface drainage potentially affects the shallow water table. This modification of hydrology has implications for future viability of agriculture and also the environmental health of waterways. Increased landscape modification and water management is likely in the coming years. The combination of sediment heterogeneity, low hydraulic gradients, and artificial drainage modification result in the plain being hydrogeologically complex. In order to understand hydrologic processes in this setting, a multi-disciplinary research programme was conducted which included a drilling program, overland electromagnetic induction and other geophysical surveys (downhole gamma log, electromagnetic induction and magnetic susceptibility) to initially establish the geologic framework. These surveys were followed by hydrogeochemical testing which includes for major and minor ions and also stable isotopes, and mineralogical analysis of drillhole material. Underlying basement rock occurs at up to 60 m depth. Unconsolidated gravel and sand deposits occur within incised paleo-valleys and are overlain by predominantly low-permeability fluvial sandy clays and estuarine and lagoonal muds. Fine-grained delta sands occur in the top 15 m of the sub-surface. Within the unconsolidated sediments, hydrodynamic trends clearly discriminated between upper unconfined and lower semi-confined aquifer systems. A comparison of surface water and shallow groundwater levels indicate limited interaction of groundwater and surface water. Hydrogeochemical analysis effectively distinguished between groundwater bodies, and also distinguished saline groundwater from seawater. Trends in major ion chemistry in the semi-confined system (particularly Na/Cl and Ca/Cl ratios) showed ion exchange accompanying saline intrusion. However, due to factors such as mineral dissolution, major ion chemistry does not clearly identify solute flux trends in the shallow aquifer system. Water stable isotope analysis (δ18O and δ2H) indicated the provenance of fresh and saline groundwater and also the relative importance of the principal hydrologic processes, i.e. evaporation and water uptake by plants. Groundwater exhibited a wide range in salinity, from very fresh to hypersaline. The formation of hypersaline groundwater was attributed largely to uptake of water by mangrove forests. Since mangrove forests were more extensive at the time of the Holocene maximum sea level (approximately 6,000 years ago) than at present, some of this groundwater may represent relict salinity from this earlier time. The relationship of relict salinity to low permeability sediments, particularly at intermediate depths, and their depositional history was examined. Vertical salinity gradients and hydrogeochemistry within these sediments varied according to position within the plain, suggesting deposition under various hydrological and sea level regimes. A preliminary investigation using analysis of stable sulfate isotopes (δ34S and δ18OSO4) was made. This study shows substantial potential for the application of this technique for quantification of solute flux and sulfur chemical transformations within settings such as this coastal plain. To establish shallow groundwater flow processes, a MODFLOW-based numerical model was used to inversely estimate aquifer parameters under various recharge scenarios. The model was designed to examine the relative importance of evapotranspiration and discharge to surface waters. However, largely due to the complexity of the drainage network and non-uniform surface water flows, the quantification of surface water- groundwater interaction by consideration of hydrodynamics is problematic. Therefore, the chemistry of groundwater and surface water was compared. While the estimated contribution of rainfall to groundwater level fluctuations was significant (46%), high evapotranspiration rates reduced net recharge and it was concluded that baseflow to drains and creeks during dry periods was insignificant, and groundwater velocities in the shallow aquifer are low. The study illustrates the value of both hydrodynamic and hydrogeochemical analyses in estuarine settings where relict salinity and groundwater-aquifer interactions impact significantly on water quality. Saline groundwater is chemically distinct from theoretical mixtures of seawater and freshwater. The study also demonstrates the value of particular chemical parameters, e.g. Na/Cl and SO4/Cl ratios and stable water isotopes, for identifying hydrologic processes in this setting.
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Buzzelli, Christopher P. "Integrative analysis of ecosystem processes in the littoral zone of lower Chesapeake Bay: A modeling study of the Goodwin Islands National Estuarine Research Reserve." W&M ScholarWorks, 1996. https://scholarworks.wm.edu/etd/1539616592.
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Approximately 40% of the bottom of Chesapeake Bay is less than 2.0 m in depth and many of these broad shoal environments are bordered by wetlands. The vegetated and nonvegetated subtidal and intertidal environment is a dynamic mosaic of highly productive estuarine habitats linked by the exchange of waterborne materials. This study developed simulation models of primary production and material exchange for four littoral zone habitats of the Goodwin Islands National Estuarine Research Reserve (NERR) in lower Chesapeake Bay. Field studies were conducted to determine the sediment biogeochemical and biomass characteristics of sandy shoal, seagrass, silt-mud, and marsh habitats. Ecological models were developed for each habitat based upon their position and ecological characteristics. The models simulate the dynamics of phytoplankton, particulate and dissolved organic carbon, dissolved inorganic nitrogen, sediment microalgae, Zostera marina, and Spartina alterniflora. Following sensitivity analysis and validation the models were used to estimate annual primary production, nitrogen processes, and material exchange. The net annual rate of phytoplankton production was 66.0, sediment microalgae ranged 101-169, Zostera marina community production was approximately 350 gC m&\sp{lcub}-2{rcub}& yr&\sp{lcub}-1{rcub}&, and Spartina alterniflora shoots and root-rhizomes produced 1150 gC m&\sp{lcub}-2{rcub}& yr&\sp{lcub}-1{rcub}& (gC m&\sp{lcub}-2{rcub}& yr&\sp{lcub}-1{rcub}&). Nitrogen uptake was in excess of demand in phytoplankton while the reverse was true for the macrophytes. The marsh habitat accounted for 43% of the total annual primary production for the ecosystem despite being the smallest habitat while the largest habitat (nonvegetated subtidal) required 52% of the total ecosystem nitrogen demand. All four habitats imported phytoplankton, particulate organic carbon, and dissolved inorganic nitrogen annually. While the intertidal habitats imported dissolved organic carbon the subtidal habitats showed net annual export. These models were developed to assess ecosystem structure, function, and change in the littoral zone of Chesapeake Bay. Ecosystem structure was assessed through field research and model development. Ecosystem function was assessed by using the model to generate annual producer, habitat, and ecosystem carbon and nitrogen budgets. The model is currently being used to investigate the interactive effects of water quality, primary production, and habitat composition in order to assess potential change in the estuary.
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Noernberg, Mauricio Almeida. "Processos morfodinâmicos no complexo estuarino de Paranaguá - Paraná - Brasil : um estudo a partir de dados in situs e Landsat-TM." reponame:Repositório Institucional da UFPR, 2001. http://hdl.handle.net/1884/48786.
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Orientador: Eduardo MaroneCo-orientadores: Rodolfo José Angulo, Evlyn M. L.M. Novo
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Tese (doutorado) - Universidade Federal do Paraná
Resumo: A análise morfodinâmica do sistema costeiro aborda os processos causadores e transformadores de feições morfológicas, bem como as forças geradoras desses processos e seus mecanismos de interação. A grande variabilidade espacial e temporal dos processos costeiros e estuarinos é um desafio para o entendimento geral tanto da freqüência quanto da magnitude desses processos, bem como de seu grau de influência no transporte e balanço de sedimentos, na morfologia costeira e nos processos ecológicos. A capacidade de análise sinóptica das imagens de satélite, dados históricos e obtidos in situ, e o potencial de análise espacial do geoprocessamento, foram empregados na identificação e compreensão dos processos morfodinâmicos no Complexo Estuarino de Paranaguá (CEP) e região costeira adjacente. O CEP possui dois eixos principais (L-0 e N-S), cujas condições ambientais (salinidade, temperatura, correntes, sólidos em suspensão, turbidez e clorofila) foram monitoradas mensalmente durante 26 meses. O eixo L-O, comparado ao eixo N-S, apresenta maior produtividade primária e sofre maior influência da bacia de drenagem. Os processos estuarinos, mais importantes, relacionados ao transporte de sedimentos são o aporte de sedimentos fluviais, de escala temporal sazonal e episódica, e a zona de máxima turbidez, a qual é regulada pela maré de sizígia. Nas margens arenosas da desembocadura do CEP, a evolução da linha de costa foi monitorada, entre 1985 e 2000, por oito imagens do satélite Landsat, as quais se mostraram úteis para tal finalidade. As alterações morfológicas apresentam padrões diferenciados de resposta, em diferentes locais da desembocadura, sob a ação das forçantes (ondas, correntes e ventos). As alterações de maior magnitude estão relacionadas à modificação no padrão anual de ventos, que por sua vez influi no estado de agitação do mar, sendo a intensificação de ventos dos quadrantes Sul e Sudeste indutora de processos erosivos. Há indícios de que estas alterações no padrão de ventos e a conseqüente variação na linha de costa estejam vinculadas ao momento de inversão entre os eventos El Nino-La Nina. O comportamento das correntes na região costeira foi descrito, e o transporte de sedimentos por tração foi estimado, utilizando dados obtidos por correntômetro eletromagnético no canal de acesso ao CEP. A deriva litorânea foi confirmada como sendo preferencialmente para Norte. O transporte por tração dos sedimentos de fimdo ocorre tranversalmente e longitudinalmente à linha de costa. As correntes de maré são as causadoras do transporte transversal à costa, o qual predomina no sentido costa afora. O transporte longitudinal à costa ocorre quase exclusivamente em momentos de intensa energia de ondas e preferencialmente para Norte. Uma imagem Landsat-7 foi obtida em um desses momentos de intensa energia, geralmente ocasionados devido à entrada de frentes meteorológicas, onde três tipos de processos costeiros (pluma estuarina, correntes de retomo e frente de superfície), relacionados a transporte de sedimentos, puderam ser descritos. A pluma estuarina, intensificada pela ressuspensão dos sedimentos de fimdo, ultrapassou a isóbata dos 20 metros. Correntes de retomo erosivas foram vinculadas a um processo de circulação de maior magnitude, envolvendo troca de propriedades entre a zona de surfe e a plataforma rasa. Fortes correntes de maré vazante de sizígia e a ressuspensão de sedimentos regularam o processo de evolução de uma frente de superfície de escala temporal de 30 horas e escala espacial da ordem de 10 km. Nesta frente foi observado transporte de sedimentos tanto transversalmente quanto ao longo da linha de costa. O CEP é particularmente vulnerável a eventos de grande energia que nele atuam, principalmente na escala temporal "evento" (dias a meses) e age como um fomrcedor de propriedades (sedimentos, nutrientes, poluentes) para a plataforma rasa. Palavras-chave: Morfodinâmica; Processos; Estuário; Zona Costeira; Transporte de Sedimentos; Monitoramento Ambiental; Landsat; Linha de Costa; Baía de Paranaguá.
Abstract: The moiphodynamic analysis of coastal systems can be applied to the study of processes that generate and transform morphologic features, as well as to understand the forcings of those processes and their interaction mechanisms. The great space and temporal variability of coastal and estuarine processes are a challenge for the general understanding of the frequency and magnitude of those processes, its influence on the sediment transport and budget, in the coastal morphology and ecological processes. The capacity of synoptic analysis of satellite images, historical data and in situ collected information, as well as the potential of geoprocessing for space analysis, were used in the identification and understanding of the morphodynamic processes in the Estuarine Complex of Paranaguá (CEP) and adjacent coastal area. The CEP has two main axes (E-W and N-S), whose environmental conditions (salinity, temperature, currents, suspended particulate matter, turbidity and chlorophyll) were monthly monitored during 26 months. The E-W axis compared to the N-S axis presents larger primary productivity and it suffers larger influence of the drainage basin. The more important estuarine processes are related to the transport of sediments, the contribution of fluvial sediments, and some episodic phenomena as well as other of seasonal scale. The maximum turbidity zone is regulated by the spring tide dynamic. In the sandy margins of the outlet of the CEP, the evolution of the coastline was monitored between 1985 and 2000 using eight Landsat images, which were shown useful for such purpose. The morphologic alterations showed differentiated patterns of response in different places of the outlet and under the action of the main acting forces (waves, currents and winds). The larger alterations are related to the modification in the annual pattern of winds, which influences the sea state. The intensification of winds of South and Southeast responsible for erosional processes. There are indications that these inter-annual alterations in the wind regime, and the consequent variation in the coastline, are linked to transition among the El Nino to La Nina events. The current behaviour in the coastal area was described, and the bedload transport of sediments was estimated using data obtained by electromagnetic currentmeters moored in the access channel of the CEP. The drift current was confirmed as being drive mainly to North. The bedload transport of the bottom sediments happens across and along the coastline. The tidal currents are responsible for the across-coast transport, which prevails in the seaward sense. The longitudinal transport happens almost exclusively in events of intense wave energy and mainly to the North. A Landsat-7 image was obtained in one of those moments of intense energy, generally due to the passage of meteorological fronts, where three types of coastal processes related to the sediment transport (estuarine plume, rip currents and surface front) could be described. The estuarine plume, intensified by the ressuspension of the bottom sediments, surpassed the isobath of 20 meters. Erosional rip currents were linked to a larger magnitude circulation process, involving change of properties between the surf zone and the inner continental shelf. High flooding spring tidal currents and the sediments ressuspension seems to regulate the evolutionary process of a surface front of temporary scale of around 30 hours and a space scale of the order of 10 km. In this front, sediment transport was observed obliquely as well as along the coastline. The CEP is particularly vulnerable to events of great energy that act in it, mainly in the "event" time scales (days to months) and it acts as an exporter of properties (sediments, nutrients, pollutants, etc.) for the inner continental shelf. Key Words: Morphodynamic Processes; Estuary; Coastal Zone; Sediments Transport; Environmental Monitoring; Landsat; Coastline; Bay of Paranaguá.
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Siqueira, Bibiana Kumpera. "Contribuição ao processo sedimentar atual no Canal do Ararapira, sistema estuarino-lagunar de Cananéia-Iguape (SP)." Universidade de São Paulo, 2007. http://www.teses.usp.br/teses/disponiveis/21/21133/tde-01072008-102612/.
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O presente trabalho tem, como objetivo, analisar o processo de sedimentação atual no Canal do Ararapira, Sistema Estuarino Lagunar de Cananéia-Iguape (SP), através das características composicionais e granulométricas dos sedimentos de fundo e distribuição da matéria orgânica sedimentar e carbonatos, relacionando estes parâmetros à configuração geral do canal e aos processos oceanográficos que ali atuam. Foram realizadas análises granulométricas, conteúdo de carbonato e matéria orgânica sedimentar (C, N, S) em 60 amostras de sedimentos coletadas em um cruzeiro oceanográfico realizado no mês de julho de 2004. Dentre o total de 60 amostras, foram selecionadas 16 para realização da análise da fração arenosa. A análise espacial da distribuição dos sedimentos e da matéria orgânica sedimentar, apontou para a predominância de sedimentos arenosos com baixos teores orgânicos ao longo de praticamente toda extensão do canal exceto em determinados pontos localizados no centro-norte do canal onde há presença de sedimentos finos associados a baixios e desembocaduras de gamboas e pequenos cursos d\'água continentais e insulares. Constatou-se a predominância da influência continental ao longo de todo o canal com pequenas concentrações de carbonatos. Os teores elementares da matéria orgânica sedimentar possuem, normalmente, comportamento e distribuição que estão diretamente relacionados aos tipos de sedimentos e à topografia de fundo, bem como à circulação. Observou-se uma relação direta entre os sedimentos mais finos e um maior conteúdo de matéria orgânica.The aim of this study is the analysis of modern sedimentary process taking place in the Ararapira Channel, at Cananéia-Iguape lagoonal estuarine system (SP). The employed parameters for this were the composition and grain size characteristics of the bottom sediments , the distribution of the carbonates , organic matter, and relates these parameters to the general configuration of the channel and to the oceanographic process that takes place over there. The grain size analysis, the carbonate content, and the sediment organic matter (C, N, S) were conducted over 60 sediment samples collected during an oceanographic cruise that took place in July 2004. Among the total of the 60 samples, 16 were selected for the coarse fraction analysis. The spatial analysis of the distribution of sediments and sedimentary organic matter showed that sandy sediments, with low organic content, are predominant practically all along the whole of the channel extension, except in points located in the central-northern portion of the channel, where there are thin sediment associated to shoals or small continental and insular river courses. The C, N, S and carbonates contents observed with the coarse fraction analysis, allow identifying the predominance of continental influence all along the channel, with lower carbonate concentrations. The sediment organic matter contents have, usually, behavior and distribution which are directly related to the type of sediment ,to the bottom topography, as well as to the circulation. It was possible to observe a direct relationship between the thin sediment and a larger content of the organic matter.
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Mahamod, Yusuff. "Sedimentary processes in the Dwyryd Estuary." Thesis, Bangor University, 1989. https://research.bangor.ac.uk/portal/en/theses/sedimentary-processes-in-the-dwyryd-estuary(ca0aea23-480c-4032-ba10-12a9adee740c).html.
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This study aims to describe and quantify the important sedimentary processes which control the dispersal and accumulation of sediment in the Dwyryd Estuary, adjacent to Tremadog Bay in West Wales. It is shown that sedimentation in the estuary is dominantly control by fast tidal currents, and in the bay by weak tidal currents. Landward transport of coastal sediments by tidal currents is the residual sediment transport path. The spatial distribution of textural parameters of the estuarine sediments is related to the strength of tidal currents as well as the morphology and bathymetry of the study area. The estuarine sediments, predominantly sand, are very similar in texture and mineralogy to the adjacent beach sediments but markedly different to the river sediments. However, the beach sediments are slightly coarser and more poorly sorted than the estuarine sediments. In contrast, sediment in the deeper parts of Tremadog Bay are finer than both the estuarine and beach sediments due to the presence of substantial admixture of mud. The grain size distributions of most of the sediments are neither lognormal nor log-hyperbolic reflecting the great variability of hydrodynamic conditions in the study area. Using previously published flume data, a new sediment transport rate formula in the form of a power law has been developed for computation of total sediment load from the bed mean grain size and flow parameters: Uc The exponent n varies from 2.7 (for 0.93 mm sand) to 4.18 (for 0.19 mm sand). This is in contrast to the Bagnold (1966) formula which regards the exponent value (equal to 3) as constant for all grain sizes. Sediment transport patterns depend on the asymmetry between flood and ebb tidal currents due to distortion of the tidal wave on entering the estuary. Estimates of sediment budgets from surveyed profiles suggest that large amounts of sand have been transported from coastal areas into the estuary, supporting the mineralogical evidence. The estimates are of the same order of magnitude as estimates using flow velocity data and the above sediment transport formula.
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Mhashhash, Aisha Fowzi. "Laboratory and numerical modelling studies of sediment flocculation processes in estuaries." Thesis, Cardiff University, 2018. http://orca.cf.ac.uk/114776/.
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Surface water is one of the fundamental parts of the environment and needs to be protected from all pollution sources for human survival. Urban development and human activities have increased the contamination of coastal and estuarine water due to insufficiently treated sewage, runoff from fertilised agricultural area and lawns and releasing industrial pollutant directly into river and estuaries. Cohesive sediment in estuaries can act as either a source or a sink of many pollutants, such as nutrients and heavy metals. Understanding the interactions between sediment and nutrients in water bodies is important because high input rates of nutrients can negatively affect water quality. The prediction of both deposition and the resuspension of cohesive sediment in estuaries supports the understanding of their turbidity, which is important in terms of the biomass of these water bodies and many of the occurring biochemical processes and the morphological processes, which determine the suitability and maintenance of fairways and harbour basins. The complex ways in which hydrodynamic and biochemical parameters affect cohesive sediment are primary reasons for the poor representation of the deposition, erosion and settling of cohesive sediment processes in modelling tools within water estuaries. However, our current understanding regarding the accurate prediction of cohesive sediment transport processes is insufficient because of flocculation processes which occur under certain circumstances (e.g. the increase of salinity in the brackish zone of rivers, which leads to the formation of flocs that are both larger and less dense than individual particles). The phenomenon of flocculation is known to play a significant role in the sediment transport processes of settling, deposition and erosion of cohesive sediment. There is no unique equation that can be universally used to predict the deposition and suspension rates of cohesive sediment because each estuary is dynamically and physically different from another and this is particularly true for the highly dynamic estuary e.g. Severn Estuary. Therefore, this study focuses on gaining a better understanding of the transport processes of cohesive sediment, including a better inclusion of the flocculation processes by developing a new settling velocity equation for cohesive sediment including flocculation processes as a function of hydrodynamic parameters. It also aims to apply this equation to a numerical model IV and to test this refined model by simulating the flocculation phenomenon in the highly dynamic Severn Estuary. This study employed an extensive experimental setup using a small scale particle image velocimetry (PIV) system. The experimental research was carried out using suspended sediment samples from the Severn Estuary in the UK. A PIV system and an image processing routine were used to measure both floc size distribution and settling velocity. The experimental results indicate that both the floc size and the settling velocity are controlled by the interaction between turbulence and salinity at salinities of less than 10 ppt. At a salinity either equal to or more than 10 ppt, both the floc size and the settling velocity were functions of only turbulent shear stress. The new equations were successfully applied in the Delft3D model; the model results show that they aptly were able to match with observed suspended sediment distributions throughout the estuary. Overall, the developed model can be regarded as a basic tool for being applied to help manage the suspended sediment processes in the Severn Estuary and for assessing the potential impact of climate change and human interference such as tidal renewable energy schemes in this water body.
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Rouas, Guy. "Étude et modélisation par éléments finis des processus hydrosédimentaires estuariens." Compiègne, 1996. http://www.theses.fr/1996COMPD884.
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L'objet de ce travail a consisté à proposer et développer une gamme de modèles pour la simulation des processus hydrosédimentaires en estuaires. Dans une première partie, un modèle bidimensionnel vertical aux éléments finis résolvant les équations couplées de l'hydrodynamique, du transport du sel et des sédiments en suspension, et enfin de l'évolution des fonds soumis à l'érosion et au dépôt a été établi. La fermeture du système nécessite l'écriture de relations constitutives complémentaires exprimant les termes turbulents, la vitesse de chute moyenne du sédiment en fonction de sa concentration et les flux d'échange au fond notamment. Un ensemble de cas tests analytiques et comportementaux ont été traités afin de valider le modèle. La réalisation d'une campagne d'essais en laboratoire pour l'étude des phénomènes de transport d'une vase de Gironde en écoulements turbulents a permis d'établir les lois de vitesse de chute du matériau d'une part et de vérifier la capacité du code à reproduire, les phénomènes de stratification induits par les effets gravitaires d'autre part. Dans une deuxième partie, une étude théorique et expérimentale fondée sur l'approche des milieux diphasiques a été conduite pour l'étude du dépôt et de la consolidation des vases en eau calme. Un modèle monodimensionnel fournissant l'évolution de la distribution verticale des concentrations au cours du temps a ainsi été développé puis calibré à partir d'essais en colonne de sédimentation.
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Le, Normant Catherine. "Modélisation numérique tridimensionnelle des processus de transport des sédiments cohésifs en environnement estuarien." Toulouse, INPT, 1995. http://www.theses.fr/1995INPT014H.
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Cette these porte sur la modelisation numerique tridimensionnelle du transport en suspension des sediments cohesifs en estuaire. Dans un premier temps, le modele numerique telemac-3d, qui simule les ecoulements tridimensionnels en riviere et en mer, a fait l'objet de nouveaux developpements afin de representer les processus propres aux sediments fins (phenomene de floculation, mouvements de la creme de vase, consolidation du fond vaseux). L'etude d'un estuaire schematique a montre les capacites du code a simuler les phenomenes caracteristiques des environnements estuariens: propagation de la maree, intrusion saline et formation du bouchon vaseux. Le modele a alors ete applique a un cas reel: l'estuaire de la loire. Le bouchon vaseux reproduit par le modele presente des caracteristiques (position dans l'estuaire, deplacements au cours de la maree) similaires a celles observees en nature. Le modele de creme de vase a aussi ete teste et il s'est avere utile pour une bonne representation de la dynamique sedimentaire estuarienne
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Qu, Wenchuan. "Studies on nitrogen cycling processes in Lake Illawarra, New South Wales, Australia." Access electronically, 2004. http://www.library.uow.edu.au/adt-NWU/public/adt-NWU20050302.161641/index.html.
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Lisa, Jessica A. "Linking structure and function of microbial communities responsible for sedimentary nitrogen processes in North Carolina estuaries." W&M ScholarWorks, 2015. https://scholarworks.wm.edu/etd/1539616745.
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Estuaries and coastal areas are highly diverse and productive ecosystems that serve as critical habitats for many marine organisms. Anthropogenic activities and changes in coastal land use have resulted in nutrient over-enrichment, posing a threat to the ecological integrity of estuaries. Nitrogen is often the limiting nutrient and its dynamics are central in determining coastal ecosystem health. The cycling and removal of nitrogen is primarily microbially mediated and the structure of these microbial communities is tightly interlaced with ecosystem function. Recycling processes nitrification and dissimilatory nitrate reduction to ammonium (DNRA) serve as a conduit for loss when coupled to the removal processes of denitrification and anaerobic ammonium oxidation (anammox). These processes occur simultaneously in estuarine sediments and are influenced by a suite of environmental factors. Understanding these interactions within the complex microbial communities, how microbial community structure responds to environmental changes, and how this relates to ecosystem function is a challenging but important goal in microbial ecology and particularly relevant in today's changing world, as climate change and sea level rise are eminent threats to coastal ecosystems. This study identified geomorphological, hydrological, and biogeochemical features, including water residence time, sediment %organics, nutrient availability, salinity, and hydrogen sulfide, that are important in controlling the community structures of nitrogen cycling microbes and their activities. Quantitative criteria were established to identify and assess the role of nitrogen removal hotspots in estuarine sediments. Specific groups of denitrifying and anammox bacteria with a higher nitrogen removal capacity were identified, suggesting the community composition is important in ecosystem function. Additionally, niche differentiation of nitrifying microbes was unveiled by linking their physiology to specific environmental parameters. Examination of microbial community structure and its response to environmental conditions combined with measurements of biogeochemical rates enabled the linkage of nitrogen cycling members with particular functions, a theme addressed throughout this dissertation.
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Andutta, Fernando Pinheiro. "O Sistema Estuarino dos rios Caravelas e Peruípe (Bahia): Observações, simulações, tempo de residência e processos difusivo e advectivo." Universidade de São Paulo, 2011. http://www.teses.usp.br/teses/disponiveis/21/21132/tde-27072011-150459/.
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O modelo numérico Delft3D-Flow foi utilizado nos estudos da distribuição e variabilidade de propriedades termohalinas, e da circulação tridimensional do sistema estuarino dos rios Caravelas e Peruípe-SERCP. Os resultados do modelo foram validados quantitativamente usando dados experimentais de marés de quadratura e de sizígia de correntes e salinidades em quatro estações fixas (duas em cada um dos estuários de Caravelas e Nova Viçosa). No processamento foram aplicadas inicialmente condições iniciais homogêneas da salinidade, densidade e dos coeficientes cinemáticos de viscosidade e difusividade vertical, e após quatro semanas de simulação foram extraídos resultados de diferentes condições. Esses resultados foram utilizados como condições iniciais mais realistas, tendo o campo espacial variado das propriedades termohalinas, e dos parâmetros físicos. Essas novas condições iniciais permitiram pular o tempo transiente otimizando assim as simulações subsequentes. A validação das simulações foi feita com base nas medições da campanha de verão, por causa do atraso do período chuvoso a vazão do rio Peruípe foi bem representativa para condições de inverno e, portanto, seria redundante usar as forçantes dos rios com valores tão próximos na validação, além da necessidade da demanda de um tempo muito maior nas analise comparativas dos resultados. Durante o verão (janeiro de 2008), os dados de vazão do rio Peruípe obtidos na Agência Nacional de Águas (ANA) levaram a estimativa da descarga fluvial de ~ 20 m3.s-1, com a extrapolação de ~ 4 m3.s-1 para vazão conjunta dos dois principais afluentes do canal estuarino do rio Caravelas (rios Cúpido e Jaburuna). As oscilações da maré foram simuladas satisfatoriamente para as quatro estações de controle utilizadas na validação, com valores médios do parâmetro Skill superiores a 0,97. As amplitudes da maré calculadas numericamente foram de aproximadamente 1,3 m e 2,5 m na quadratura e sizígia, respectivamente. Os resultados numéricos das simulações das velocidades foram melhores em condições de sizígia com valores médios do parâmetro Skill entre 0,77 e 0,93, enquanto que na quadratura esse parâmetro variou entre 0,38 a 0,65. Para a estrutura de salinidade durante as condições de maré de sizígia, melhores resultados no SERCP do skill e, portanto abrangendo as quatro estações de controle, foram confirmados pelos parâmetros Skill médios superiores a 0,83. Na maré de quadratura os correspondentes valores médios também foram relativamente altos, variando entre 0,73-0,85. Entretanto, houve dificuldades em simular adequadamente a alta estratificação (vertical e longitudinal) do estuário de Nova Vicosa, podendo-se atribuir esse fato à maior vazão do rio Peruípe, que é muito maior do que a do rio de Caravelas. Com os resultados da estrutura de salinidade a intrusão da massa de Água Tropical (AT) foi adequadamente representada nos quilômetros iniciais do canal estuarino do rio Caravelas, e na parte interna da desembocadura na região de Nova Viçosa. Movimentos bidirecionais foram observados nos resultados das simulações na preamar e baixamar, na região de desembocadura dos estuários da Caravelas e Nova Viçosa, movimentos estes forçados pela componente baroclínica da força de gradiente de pressão. Vale ressaltar que o efeito baroclínico ficou mais visível nos instantes da baixamar. Na preamar para a maior parte destas duas regiões verificou-se apenas um pequeno desvio no sentido das correntes entre superfície (Z = -0,1) e fundo (Z = -0,9) e em geral inferior a 30 graus. Usando os traçadores lagrangeanos virtuais lançados ao longo dos canais estuarinos das entradas norte (Caravelas) e sul (Nova Viçosa) do SERCP foi obtido como resultado um tempo de residência relativamente pequeno e comparável ao estuário tropical do rio Curimataú. No trecho analisado no canal estuarino do rio Caravelas, a ~ 3 km e ~ 12 km distantes da Boca do Tomba o tempo de residência médio foi ~ 4,2 dias e ~10,3 dias, respectivamente. Já no estuário de Nova Viçosa, ou canal estuarino do rio Peruípe, apenas o trecho inicial de 5 km foi considerado para o lançamento dos traçadores, e os tempos de residência de ~ 1,5 dias e 2,5 dias foram estimados para as posições de ~2,5 km e 5,0 km distantes da desembocadura. O modelo analítico proposto e usado no cálculo de tempo de residência teve resultados comparáveis aos obtidos pelas simulações pelo método lagrangeano do Delft-3D Flow. Diferentemente, o modelo LOICZ apresentou valores bem diferentes do tempo de residência para os seis estuários analisados (Caravelas, Nova Viçosa, Curimataú, Hudson, Conwy and Mersey), em geral bem inferiores aos do modelo proposto, indicando assim uma possível estimativa maior do fluxo difusivo na formulação do modelo LOICZ.The numerical model Delft-Flow was used to study the spatial distribution and variability of the termohaline properties, and the tridimensional circulation in the estuarine system of the rivers Caravelas and Peruípe. The model results were validated quantitatively using field data of tidal oscilation and currents, and salinity measurements during neap and spring tides at four mooring stations, two in each estuary. In the data processing homogeneous conditions were used initially for the fields of salinity, density and the vertical kinematic coeficients of viscosity and diffusivity, then after four weeks of running simulation those fields were saved with spatially varied conditions. Those results were used for a more realistic initial condition, thus having a varied field of the termohaline properties, and of the physical parameters. The new initial conditions allowed avoiding the transient time and thus optimizing the following simulations. The model evaluation was done based on measurements undertaken during the summer season, because of the delay in the raining season, the Peruípe river discharge was low and more representative of dry season condition, for those reasons we just used the measurement taken in the January 2008. In the summer the measurements of the Peruíbe river discharge taken from the Agência Nacional de Águas (ANA), and the river flow of was estimated at ~ 20 m3.s-1, with the extrapolation of ~ 4 m3.s-1 for the unified flow from the rivers Cúpido and Jaburuna, with contribute to the flow in the Caravelas estuary. Tidal oscillation at neap and spring tides were well simulated for the 4 controling sites used to the validation, and with the mean skill values over 0.97. The tidal amplitudes were numerical calculated and nearly between 1.3 and 2.5 meters at neap and spring tides, respectively. The numerical results of the velocities were better simulated in spring tides with the mean skill values in the range of 0.77 and 0.93, while at neap tides this parameter varied between 0.38 and 0.65. For the salinity structure at spring tides good results in the estuarine system were achieved, hence comprising all the controling station for validation, with all mean skill values over 0.83. At neap tides the corresponding mean skill values were relatively high, varing in the range of 0.73-0.85. In addition, there were difficulties in simulation adequately the highly vertical and longitudinal stratification of the Nova Vicosa estuary. That was caused by the stronger river inflow of the Peruípe River, which is much higher than the inflow by Caravelas River. The intrusion of the Tropical Water mass (TW) was properly simulated given the right distribution of the salinity along the first quilometers of the estuarine channel of Caravelas, and the internal part of the Nova Viçosa estuarine mouth. Bidirectional movements were observed from the model outputs at the high and low tides, at the region near the mouth of both, Caravelas and Nova Viçosa estuary. Those moviments are forced by the baroclinic component of the pressure gradient. Is worth to mention the the baroclinic effect was better observed at the low tides of these regions. At high tide most of areas showed only a small change in the current direction between surface (Z = -0.1) and bottom (Z = -0.9) and usually smaller than 30 degrees. The virtual lagrangian drifters released along the estuarine channels of Caravelas (north) and Nova Viçosa (south) have shown a residence time relatively short, and comparable to the Curimataú tropical estuary. In the released location between 3 and 12 km of distance from the Caravelas mouth, the residence time was in the range of 4.2 and 10.3 days. Differently, at the Nova Viçosa estuary, only the first 5 km were studied and the residence time of 1.5 and 2.5 days was estimated for the respectives positions of 2.5 and 5.0 km away from the mouth. The analytical model proposed and used to calculate the residence time leaded to results comparable to the results from the numerical simulation using the Lagrangian method of the Delft-3D Flow. Differently, the LOICZ model has shown results really different of the residence time for all the six estuaries (Caravelas, Nova Viçosa, Curimataú, Hudson, Conwy and Mersey), and in general much smaller then the results from the proposed formula, thus indicating a possible overestimation of the diffusive flux assumed in the LOICZ formulation.
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Rybarczyk, Hervé. "Processus d'eutrophisation et ses consequences sur les peuplements d'un ecosysteme estuarien macrotidal, un exemple en manche orientale : la baie de somme." Paris 6, 1993. http://www.theses.fr/1993PA066231.
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La baie de somme est un domaine marin macrotidal de la manche orientale. Elle recoit par l'estuaire de la somme des apports en sels nutritifs en provenance d'un bassin versant marque par une agriculture moyenne. Pour prendre en compte cette situation d'interface une problematique et une methodologie originale de prelevement sur ces vastes estrans (72 km#2) ont ete developpees. Les principaux resultats obtenus montrent que les eaux de la baie sont distinctes des eaux cotieres. Physiquement avec une isohaline de 29,5 g/l##1 et biologiquement car elles correspondent a un peuplement phytoplanctonique particulier assujetti a la dessalure et domine par le genre asterionella. De plus les teneurs en chlorophylle a y sont en moyenne trois fois plus elevees qu'au large. La somme, avec 25 m#3/s##1 de debit moyen joue un role non negligeable dans le processus d'eutrophisation de la baie pourtant soumise a un regime macrotidal. Le volume oscillant possede un temps de renouvellement moyen de 8 jours soit 16 cycles de maree environ. L'etude de la distribution des sels nutritifs selon la salinite a permis de mettre en evidence des variations saisonnieres mais egalement spatiales. Une production d'ammonium est observable directement en relation avec les fortes biomasses des especes benthiques estuariennes. La production primaire elevee, resultant de l'eutrophisation des eaux de la baie est suivie d'une forte degradation de matiere organique et une liaison significative a ete mise en evidence entre l'augmentation des concentrations en pheopigments a et la depletion en oxygene de l'eau de mer recouvrant les estrans. L'approche experimentale des phenomenes d'anoxie a conduit a determiner comme parametre essentiel des mortalites les importantes biomasses des especes benthiques, notamment cerastoderma edule. Un modele de situation d'anoxie et des abaques de survie en fonction de la saturation en oxygene dissous, de la temperature et de la biomasse a ete realise. Ce travail met en evidence l'originalite du fonctionnement hydrologique de la baie de somme. Au travers de l'etude experimentale de l'excretion d'ammonium par les especes benthiques, il souligne le role de leurs biomasses dans cette eutrophisation. Il etablit un lien direct entre le processus d'eutrophisation et les mortalites par anoxie dans un domaine macrotidal
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Santos, Marcus Vinicius Peralva. "Utilização dos Componentes Biogênicos do Sedimento na Interpretação de Processos Sedimentares na Região Estuarina do Rio Jacuípe, Litoral Norte da Bahia." Instituto de Geociências, 2012. http://repositorio.ufba.br/ri/handle/ri/21499.
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O presente trabalho teve como objetivo analisar os processos de sedimentação, transporte e energia hidrodinâmica atuantes na região estuarina do rio Jacuípe, Litoral Norte da Bahia, utilizando-se, para este fim, os componentes biogênicos do sedimento. Foram realizadas duas campanhas amostrais, uma na estação seca e outra na estação chuvosa, obtendo-se um total de 32 amostras de sedimento superficial de fundo, por campanha amostral, ao longo do canal principal do estuário, por meio de dragagem. Após lavagem e secagem das amostras, os 300 primeiros grãos bioclásticos foram submetidos a triagem, identificação e descrição de seus aspectos tafonômicos (coloração, desgaste e arredondamento), sendo parte das amostras submetidas a análise da fauna de foraminíferos, teor de carbonato e a analise granulométrica. Os resultados obtidos foram submetidos aos tratamentos estatísticos de abundância (absoluta e relativa), testes de Spearmann e Mann-Whitney e as análises de regressão simples e múltipla. Constatou-se o predomínio das categorias biogênicas madeira, alga, foraminífero bentônico e tecameba, sendo a distribuição dos grãos influenciada pela ação das corrente marinhas e fluviais. Grãos como algas calcárias, Halimeda, briozoários, cnidários, poliquetas, caranguejo, craca, gastrópodo, bivalve e escafópodo tendem a se concentrar nas regiões próximas a desembocadura do estuário, enquanto fragmentos de diatomácea, tecameba e foraminíferos planctônicos, tendem a se concentrar na região central do estuário e as demais categorias apresentaram distribuição variada. A dominância de grãos sem arredondamento, com abrasão e de coloração branca em ambas as estações, indicam um incremento constante de novos grãos ao estuário, sendo o transporte dos mesmos ocorrendo preferencialmente via arrasto. As testas de foraminíferos mostraram-se bem preservadas (grãos naturais) e com predomínio da coloração branca, indicando um transporte por suspensão das mesmas. Os valores do teor de carbonato indicam uma maior contribuição siliciclástica ao estuário e a granulometria predominante é a areia fina. Com base nos resultados obtidos, pode-se assim, descrever o estuário do rio Jacuípe como sendo um estuário de sedimentação recente (dominância de grãos atuais), com o transporte de grãos ocorrendo preferencialmente via arrasto (dominância de grãos abrasados) e por uma baixa energia hidrodinâmica em ambas as estações (dominância da fração areia fina), não sendo possível relacionar qual parâmetro ambiental influencia a distribuição dos bioclastos.
ABSTRACT - This study aimed to analyze the processes of sedimentation, hydrodynamic transport and energy working on the estuary of the river Jacuípe, north coast of Bahia, using for this purpose, the components of the biogenic sediment. There were two sampling campaigns, one in the dry season and another in the rainy season, resulting in a total of 32 surface sediment samples from the background by sampling campaign along the main channel of the estuary by dredging. After washing and drying of samples, the first 300 bioclastic grains were subjected to screening, identification and description of Taphonomic aspects (color, wear and rounding), being part of the samples and analysis of the fauna of foraminifera, carbonate content and particle size analysis . The results were subjected to statistical treatment of abundance (absolute and relative), Spermann tests and Mann-Whitney and analysis of simple and multiple regression. It was observed the predominance of biogenic categories wood, algae, benthic foraminifera and tecameba, and the distribution of grains influenced by the action of ocean currents and river. Grains such as calcareous algae, Halimeda, bryozoans, cnidarians, polychaetes, crabs, barnacles, gastropods, bivalves and escafópodo tend to be concentrated in areas near the mouth of the estuary, while fragments of diatom, and planktonic foraminifera tecameba, tend to concentrate in the region central estuary and the other categories showed varied distribution. The dominance of grain without rounding, abrasion and white coloration in both seasons, indicating a constant growth of new grains to the estuary, and transport occurs preferentially via the same drag. The foraminifers tests showed well preserved (natural grain) and predominantly white in color, indicating a suspension of transport for them. The values of carbonate content indicate a greater contribution to the estuary and siliciclastic grain size is predominantly fine sand. Based on these results, one can thus describe the estuary of the river as an estuary Jacuípe sedimentation recent (current dominance of grains), with the transport of grains occurs preferentially via drag (dominance of abrasive grains) and a low hydrodynamic energy in both seasons (dominance of fine sand fraction), it is not possible to relate environmental parameter which influences the distribution of bioclasts.
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Calado, Leonardo Luiz. "Mapeamento cromoss?mico de genes ribossomais em esp?cies estuarinas da fam?lia Gerreidae Identifica??o de uniformidade cariot?pica e sua empregabilidade com fins biotecnol?gicos - REPROGEN." Universidade Federal do Rio Grande do Norte, 2013. http://repositorio.ufrn.br:8080/jspui/handle/123456789/12653.
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Previous issue date: 2013-07-19Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico
Perciformes are dominant in the marine environment, characterized as the largest and most diverse fish group. Some families, as Gerreidae, popularly known as silver jennies, carapebas, or mojarras have a high economic potential to marine fish farming, natural explotation and game fishing. Genetic information of these species are of fundamental importance for their management and production. Despite exist over 13,000 marine fish species described, only 2% were cytogenetically analyzed and less than 1% have some reproductive characteristics known. Induced breeding, cytogenetic characterization and cryopreservation of gametes, represent important areas in applied fish studies. In this project cytogenetic analyzes were performed to acess genetic aspects of Gerreidae species, distributed in coastal and estuarine regions of Northeast Brazil. Different methods for identifying chromosomal regions were employed using conventional techniques (Ag-NORs, C-banding), staining with base-specific fluorochromes (DAPI-CMA3), and physical mapping of ribosomal genes 18S and 5S rDNA, through hybridization in situ with fluorescent probes (FISH). The six species analyzed showed remarkable chromosome conservatism. The 18S and 5S ribosomal genes when analyzed in phylogenetic perspective demonstrate varied evolutionary dynamics, suggesting ocurrence of stasis process in some groups and greater dynamism in others. Double FISH with 18S and 5S probes showed both how efficient cytotaxonomic markers in the homogeneous karyotypes of this group of species. The karyotypic pattern identified in addition to the evolutionary aspects of karyotype, are suggestive of existence of low potential of post-zygotic barrier, prompting further research to prospect for artificial interspecific hybridization of these species of commercial importance
Os Perciformes s?o dominantes no ambiente marinho, contituindo a maior e mais diversificada ordem de peixes dentre os tele?steos. Muitas de suas fam?lias, como os Gerreidae, conhecidos popularmente como carapicus, carapebas, ou mojarras, t?m um alto potencial econ?mico, no que se diz respeito ? piscicultura marinha, extrativismo e pesca esportiva. Informa??es gen?ticas destas esp?cies s?o de fundamental import?ncia para seu manejo e produ??o. Mesmo assim, das 13.000 esp?cies de peixes marinhos descritos, apenas 2% foram estudadas sob o ponto de vista citogen?tico e menos de 1% sobre suas caracter?sticas reprodutivas. A reprodu??o induzida, a citogen?tica e a criopreserva??o de gametas, representam importantes ?reas aplicadas de estudo em peixes. No presente trabalho an?lises citogen?ticas foram empregadas na caracteriza??o gen?tica de esp?cies da fam?lia Gerreidae, ocorrentes no litoral do Nordeste do Brasil. Diferentes m?todos de identifica??o de regi?es cromoss?micas foram empregados por meio de t?cnicas convencionais (Ag-RONs, bandamento C), colora??o com fluorocromos base-espec?ficos (DAPI-CMA3), e mapeamento cromoss?mico de genes ribossomais marcadores DNAr 18S e 5S, atrav?s da hibrida??o in situ com sondas fluorescentes (FISH). As seis esp?cies analisadas revelaram marcante conservadorismo cromoss?mico. Os genes ribossomais 18S e 5S quando analisados em perspectiva filogen?tica, demonstram din?mica evolutiva variada, podendo apresentar estase em alguns grupos e maior dinamismo em outros. As an?lises por duplo-FISH dos s?tios 18S e 5S se revelaram eficientes marcadores citotaxon?micos nos cari?tipos homog?neos deste grupo de esp?cies. Os padr?es cariot?picos identificado, al?m dos aspectos evolutivos do cari?tipo identificados, s?o sugestivos de baixo potencial de barreiras p?s-zig?ticas, instigando pesquisas futuras de prospec??o de hibrida??o interespec?fica destas esp?cies de valor comercial
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Bachelet, Guy. "Processus de recrutement et rôle des stades juvéniles d'invertébrés dans le fonctionnement des systèmes benthiques de substrat meuble en milieu intertidal estuarien." Bordeaux 1, 1987. http://www.theses.fr/1987BOR10568.
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Bachelet, Guy. "Processus de recrutement et rôle des stades juvéniles d'invertébrés dans le fonctionnement des systèmes benthiques de substrat meuble en milieu intertidal estuarien." Grenoble 2 : ANRT, 1987. http://catalogue.bnf.fr/ark:/12148/cb37602511w.
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Marion, Claire. "Processus de sédimentation fine en domaine estuarien macrotidal : approche trans-disciplinaire et multi-échelles : application à l'estuaire de l'Authie, Nord de la France." Littoral, 2007. http://www.theses.fr/2007DUNK0188.
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Les mécanismes contrôlant la dynamique des sédiments fins en milieu estuarien sont complexes du fait de la multiplicité des processus en action et de leurs interactions diverses et encore souvent mal comprises. L’étude de la dynamique des sédiments fins regroupe quelques uns des enjeux environnementaux fondamentaux. En raison de leur forte affinité avec une large gamme de contaminants métalliques et organiques, les particules fines sont en mesure de concentrer la pollution provenant à la fois du bassin versant et du milieu marin et dont les risques respectifs sont croissants (agriculture, trafic maritime…). Leur accrétion mène à la formation de vasières puis à l’édification de marais maritimes, habitats d’importance communautaire au niveau européen. La pérennité de ces espaces ainsi que la biodiversité et la maintenance des ressources qu’ils contiennent sont cependant menacées par le comblement général des estuaires. Les travaux effectués lors de cette thèse ont permis de dégager quelques points clefs du fonctionnement d’un estuaire co-dominé par la houle et la marée en soulignant notamment les interactions entre les différents processus. Ils ont également permis d’appliquer un ensemble d’outils et de croiser les regards scientifiques par le biais d’une méthodologie transdisciplinaire. Les études à l’échelle de la marée ont mis en évidence l’influence significative mais restreinte de la houle au domaine d’embouchure, la mixité des masses d’eau et la présence d’un maximum de turbidité résultant d’un jeu d’asymétrie de la marée. Cette pompe tidale est en mesure de redistribuer les sédiments très largement au sein de l’estuaire, notamment par le biais de macroflocs. Les interactions entre la morphologie et les asymétries de marées sont complexes et, à travers le transport résiduel engendré, conditionnent l’évolution du système estuarien. La dynamique tidale est particulièrement bien enregistrée à travers la nature des dépôts et leurs rythmicité. Les suivis ont montré une constante disponibilité des MES dans les masses d’eau et le rôle clef de vecteur des chenaux de marée. Les apports de sédiments sur les zones intertidales se font ensuite selon les niveaux altimétriques. Les différents résultats ont mis en évidence l’importance de la spartine dans les mécanismes de piégeage des sédiments sur les marais salés et leur variabilité saisonnière mais également les répercussions que pouvaient avoir les forts taux de sédimentation sur les biocénoses benthiques à moyen terme. Sur une échelle plus longue, nous avons pu envisager les conséquences en termes d’élévation de cette accumulation en soulignant l’effet de la compaction du profil sédimentaire. Le volet stratigraphique, prenant en compte les conclusions de l’histoire holocène de la plaine maritime flamande, confirme le stade de comblement avancé de l’estuaire. Les recherches sur l’estuaire de l’Authie sont susceptibles de déboucher sur un modèle d’estuaire à dominance hydrodynamique mixte marée-houle, pertinent pour des estuaires macrotidaux tempérés situés dans des domaines à forte disponibilité en sables et répondant à ces critères hydrodynamiques (estuaire de la Manche). Les perturbations d’ordre climatique et la variabilité naturelle qui s’amorcent dans le cadre du changement global s’accompagnent d’une pression humaine de plus en plus forte sur les espaces estuariens. Ces risques devront nous obliger à appréhender les écosystèmes estuariens de manière holistique en les replaçant au niveau régional de la Manche mais également dans le contexte mondialThe mechanisms controlling fine sediments dynamics in estuaries are complex because of the multiplicity of active processes and their diverse interactions, most often not well understood. The study of fine sediment dynamics embodies a number of fundamental environmental issues. Due to their strong affinity with a large range of metallic and organic contaminants, fine-grained deposits are capable of concentrating pollutants from watersheds and from the sea, both of which are sources of increasing coastal zone hazards (from agriculture, maritime traffic. . . ). Accretion of estuarine deposits leads to mudflat formation, and then salt marsh establishment, thus forming habitats of supreme importance in the European community. The lasting biodiversity and resource value of these habitats are at risk from accelerated estuarine infilling. The objective of this thesis has been to highlight key points of the functioning of an estuary co-dominated by waves and tides, and to gain better insight into the interactions underlying fine-grained sedimentation processes. The approach is highly methodological, based on the application of a cross-disciplinaryassemblage of tools. The study shows that wave influence, though significant, is restricted to the esturary mouth. The esturary exhibits freshwater/salinity mixing and the presence of a turbidity maximum resulting from a combination of tidal asymmetries. This tidal pumping is capable of very widely redistributing the sediment within the estuary, notably via macrofloc dynamics. Interactions between tidal asymmetry and morphology are complex and, through generated residual transport, condition the evolution of the estuarine system. The tidal dynamics are particularly well recorded by the characteristics of deposited sediments and their clear rhythmic pattern. The monitoring has shown the constant availability of sediment in the water column and the key role of tidal channels as vectors of sediment circulation. The input of sediment over the intertidal zones is governed by elevation within the tidal frame. The different results have highlighted the importance of Spartina in sediment trapping mechanisms over salt marshes and their seasonal variability but also the medium-term impacts of high sedimentation rates on benthic biocoenoses. At longer timescales, investigation of the consequences of this accretion highlights the effect of compaction of the sedimentary profile. The stratigraphic input from this work takes into account conclusions from the Holocene history of the neighbouring Flemish coastal plain, and confirms the advanced stage of infilling of the Authie esturay. The research on the Authie estuary may be summarised by a model of an estuary with mixed wave-tide hydrodynamic dominance pertinent to temperate macrotidal estuaries located in sand-rich tidal seas with storm wave influence, which is precisely the case of English Channel estuaries. Climatic perturbations and natural variability initiated within the frame of global change result in increasing human pressures on estuaries, thus generating potential risks. Tacking these pressures and risks calls for a holistic approach to the study of estuarine ecosystems, not only at the regional scale of the English Channel, but also in the world context
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Joaquim, João Marcos Barreiros. "Avaliação da composição das águas e dos processos de circulação e mistura no sistema estuarino-lagunar do Itapocu, como subsídio ao ordenamento do uso da água." reponame:Repositório Institucional da UFSC, 2012. http://repositorio.ufsc.br/xmlui/handle/123456789/94558.
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Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Filosofia e Ciências Humanas, Programa de Pós-Graduação em Geografia, Florianópolis, 2010.Made available in DSpace on 2012-10-25T12:06:40Z (GMT). No. of bitstreams: 1 280536.pdf: 1109467 bytes, checksum: 72e555876c071bdb1ad00a3e768076b0 (MD5)
O presente trabalho busca um entendimento dos processos de circulação e mistura no Sistema Estuarino-lagunar do Itapocu, entre os municípios de Barra Velha e Balneário Barra do Sul. A pesquisa visa o entendimento desses processos tendo como objetivos a determinação dos principais parâmetros físico-químicos da coluna d'água, tendo como referências a salinidade, temperatura, turbidez, oxigênio dissolvido e pH. Além desses parâmetros foi realizada uma investigação sobre o padrão de circulação das correntes nas proximidades da desembocadura do Sistema Estuarino-lagunar do Itapocu, a aquisição desses dados foi viabilizada pela utilização de um ADCP, que realiza um perfilação identificando as direções e velocidades das correntes. A estratégia amostral foi definida contemplando quatro campanhas amostrais, uma a cada estação do ano, para que se obtivesse uma leitura da variabilidade sazonal das propriedades, esses trabalhos eram sempre realizados sob a condição de Sizígia, durante um ciclo de completo de maré (13 horas). Os parâmetros hidrodinâmicos se mostraram fortemente dependentes das condições meteorológicas, foi claramente percebida a influência das águas continentais, através do rio Itapocu, nos episódios de chuvas mais intensas. Nesses casos devido o aumento da vazão fluvial e diluição das águas marinhas, por vezes não pode ser percebida uma estratificação da coluna d'água. O mesmo pode ser notado nas condições de menor intensidade das chuvas, só que nesse caso há um predomínio das águas marinhas ao longo da coluna. As correntes na desembocadura do sistema foram de baixa intensidade e mostraram a multiplicidade das forças naquela área, revelando um padrão irregular no seu sentido em algumas das campanhas amostrais.
The present essay tries to show some understanding of the processes of the flow and the mixture on the Itapocu Lagoon-Estuary System, between the cities of Barra Velha and Balneário Barra do Sul. The research shows the understanding of those processes having as objectives the determination of the main physics-chemical features of the water column, having as references the saltiness, temperature, turbidity, diluted oxigen and pH. Besides these features, an investigation about the standard of the stream flowing near the mouth of the Itapocu Lagoon-estuary System was realized, the acquisition of these data was straightened due to the use of a ADCP, which realizes a perfilation identifying the directions and the speed of the streams. The showing strategy was defined contemplating four sampling campaigns, one in each season of the year, so that a sample of the season of the variability of the properties was obtained, these works were always realized under the Sizígia condition, during a complete tide cycle (13 hours). The hidrodinamical parameters showed themselves strongly dependent on the weather forecast conditions, the influence of the continental Waters were clearly realized, throughout Itapocu river, on the more intense raining episodes. In these cases due to the rising of the water flow and the diluition of the sea waters, a stratification of the water column sometimes cannot be realized. The same cannot be noticed on the conditions of minor raining intensity, but in this case there is a predominance of sea Waters along the column. The streams on the mouth of the system have been the ones of low intensity and have shown the multiplicity of the forces in that area, revealing an irregular standard in its way in some of the sampling campaigns.
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Cordier, Mateo. "Ecosystème estuarien et système économique régional: faisabilité d'une intégration par modélisation input-output : application au cas de l'habitat halieutique dans l'estuaire de la Seine." Doctoral thesis, Universite Libre de Bruxelles, 2011. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/209905.
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Le modèle input-output régional environnementalisé développé dans la thèse de M. Cordier suggère qu’il serait possible de restaurer 25% des surfaces naturelles de nourriceries de poissons détruites dans l’estuaire de la Seine entre 1834 et 2004. Le modèle suggère que la mesure de restauration pourrait augmenter de 15% à 23% la biomasse de soles produite dans l’estuaire par rapport à une situation sans mesure. Quant à l’effet des coûts de restauration sur les agrégats macroéconomiques (PIB, emploi, etc.), il génère une diminution qui ne dépasse pas 0,5% par rapport à une situation sans mesure. Le modèle montre cependant que trois secteurs sont particulièrement touchés par la mesure, leur bénéfice étant considérablement réduit. Cela indique le compromis à réaliser entre les objectifs écologiques à long terme et les objectifs économiques sectoriels à court terme. La quantification des compromis par le modèle constitue un atout utile aux processus de décision participatifs multicritère / The regional green input-output model developed in Mateo Cordier's PhD shows that it seems possible to restore 25% of the natural areas of fish nurseries destroyed in the Seine estuary between 1834 and 2004. The model suggests that the restoration measure could increase between 15% and 23% the biomass of sole generated by the estuary compared to a situation without measure. Regarding the impact of restoration costs on macro-economic indicators (GDP, employment, etc.), it generates a decrease that does not exceed 0,5% compared to a situation without measure. However, the model shows that three sectors are particularly impacted by the measure. Their benefits are considerably reduced. This shows the trade-off that occurs between ecological targets on the long run and economic targets on the short run. The quantification of such trade-offs in the model is particularly useful to public participation in decision-making.Doctorat en Sciences agronomiques et ingénierie biologique
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Voltz, Baptiste. "Dynamique de la matière organique au sein dans les estuaires picards : caractérisation des faciès biosédimentaires et quantification des processus de minéralisation benthique." Thesis, Littoral, 2020. http://www.theses.fr/2020DUNK0579.
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Les estuaires assurent une production élevée et le transfert d'une grande quantité de matière organique (MO) du continent vers l'océan. Une étape importante pour comprendre les échanges de MO à l'interface continent - océan, le long de la côte française de la Manche Orientale, est d'établir un bilan de MO dans les trois plus grands estuaires : la Canche, l'Authie et de la Somme. Dans ce but, il a été réalisé une description sédimentologique et biologique du sédiment de surface et une caractérisation élémentaire et isotopique distinguant l'origine de la MO sédimentaire. La caractérisation du sédiment de surface a été réalisée, de l'étage proche subtidal à supratidal, le long de transects transversaux au fleuve, constituant un réseau de 36, 37 et 39 stations respectivement pour l'estuaire de la Canche, de l'Authie et de la Somme. A partir de cette approche cartographique, un transect représentatif dans l'estuaire de la Canche et de l'Authie a été sélectionné, dans le but de quantifier la minéralisation benthique de la MO sédimentaire, le long du gradient tidal et finalement d'établir un bilan de la dégradation de la MO à l'échelle de l'estuaire. A partir de la caractérisation sédimentologique et biologique du sédiment de surface, le paysage estuarien a été défini selon quatre faciès biosédimentaires : les bancs et plateformes sableuses, les vasières, le bas et le haut des prés salés. Il a été démontré que la répartition de la MO à l'échelle de l'estuaire est contrôlée par la distribution de ces différents faciès biosédimentaires. En effet, les sédiments sableux sont soumis à des contraintes hydrodynamiques importantes dans lequel le dépôt de la MO est limité. En revanche, la MO se dépose préférentiellement dans les lieux où les sédiments fins s'accumulent tels que les vasières et les prés salés. Ces deux environnements sédimentaires sont soumis à des contraintes hydrodynamiques plus faibles, plus particulièrement les prés salés, où la végétation favorise le dépôt et limite la remise en suspension de la MO sédimentaire. En effet, les fortes quantités de MO sédimentaire mesurées dans les prés salés sont issues de la contribution des halophytes en C3 dominant le haut des prés salés. Néanmoins, notre étude montre que la MO déposée le long du gradient tidal est aussi dépendant de l'apport de MO particulaire provenant des communautés phytoplanctoniques fluviatiles et marines/estuariennes. De plus, cette étude a mis en évidence des différences géomorphologique avec un état de maturité des prés salés avancée dans l'estuaire de la Canche, une progradation du pré salé en rive dans l'estuaire de l'Authie et une régression du pré salé, en rive nord dans l'estuaire de la Somme, issu d'un comblement avancé. A l'immersion et à l'émersion, les vasières et les prés salés ont une contribution plus importante que les sédiments perméables à la minéralisation benthique. Paradoxalement, le bilan de la minéralisation benthique, relève une contribution non négligeable des sédiments perméables dans l'estuaire de l'Authie, étant donné leur vaste répartition à l'échelle de l'estuaire. Il a été démontré que la variation spatiale de la minéralisation benthique repose sur les caractéristiques sédimentologiques des faciès biosédimentaires mais aussi sur les facteurs biologiques tels que la macrofaune benthique, le microphytobenthos et le système racinaire des halophytes. Cette thèse contribue à une meilleure définition du rôle des estuaires picards dans le cycle de la MO et permet un premier pas vers la quantification d'un bilan de MO dans les trois principaux estuaires de la Manche OrientaleEstuaries ensure a high production and transfer a large amount of organic matter (OM) from continent to ocean. To understand OM exchanges at the continent-ocean interface along the eastern English Channel coast, it is primordial to establish a mass balance OM budget in the three main estuaries : the Canche, the Authie and the Somme estuaries. In this frame, the sedimentary OM distribution and origin were studied by coupling a sedimentological description of surficial sediments and an elemental and isotopic characterization of the sedimentary OM. Such approach was carried out from near from subtidal to supratidal stages, along transects transversal to the main river channel, resulting in a sampling of 36, 37 and 39 stations respectively from the Canche, the Authie and the Somme estuaries. Based on this mapping approach, a representative transect was selected in the Canche and the Authie estuaries in order to quantify the sedimentary OM benthic mineralization along the tidal gradient and finally to establish an OM mineralization budget at the estuarine scale. Based on the sedimentological and biological characterization of sediments, the estuarine landscape was described according to four biosedimentary facies : sand flats, mud flats, low and high marshes. This study evidenced that the distribution of OM at the estuary scale is mainly controlled by the distribution of these biosedimentary facies. Indeed, sand flats are subject to intense hydrodynamic conditions in which sedimentary OM deposition is limited. On the other hand, OM is preferentially deposited in fine-grained sediments such as mud flats and salt marshes. Both of these sedimentary environments are subjected to lower hydrodynamic conditions, especially salt marshes, where vegetation enhances deposition and limits the resuspension of sedimentary OM. Indeed, the high quantities of sedimentary OM measured in salt marshes mainly originate from C3 halophytes dominating high marsh areas. Nevertheless, our study also evidenced that the deposition of sedimentary OM along the tidal gradient depends on the contribution of particulate OM from fluvial and marine/estuarine phytoplankton communities. Moreover, this study has demonstrated that various evolutions of the geomorphological features, with a mature salt marsh present in the Cancheestuary, a seaward prograding salt marsh on the north shore of the Authie estuary, a salt marsh retreat on the north shore of the Somme estuary resulting from an advanced sand infilling. The OM benthic mineralization campaigns demonstrated that during immersion and emersion periods, mud flats and salt marshes are the main contributors to total OM mineralization along the tidal gradient in contrast to sand flats. The spatial variation mainly depended on the sedimentological characteristics of each of biosedimentary facies but also on biological factors such as benthic macrofauna, microphytobenthos and root system of halophytes. The OM mineralization budget at the estuarine scale showed a significant contribution of sand flats in the Authie estuary given their wide distribution. This thesis contributes to a better definition of the role of "Picard" estuaries in the OM cycling and allows a first step towards the quantification of a mass balance OM budget in the three main estuaries of the eastern English Channel coast
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Roets, Adriaan. "A preliminary analysis of the sediment budget across the Swartvlei estuary mouth." Thesis, Stellenbosch : Stellenbosch University, 2014. http://hdl.handle.net/10019.1/95958.
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Thesis (MEng)--Stellenbosch University, 2014.ENGLISH ABSTRACT: The Swartvlei estuary and lake system is situated on the southern coast of the Western Cape Province of South Africa and forms part of the core conservation area of the Wilderness National Park. The Swartvlei system comprises two interlinked water bodies, namely Swartvlei Lake and Swartvlei estuary. SANParks have been monitoring this estuary closely over the past two decades, due to its importance to the ecology and to tourism. There are also low-lying properties on the perimeter of the Swartvlei estuary which run the risk of occasional flooding. Two of the major monitoring issues in this estuary system are the water level required for successful mouth breaching, and the influence of the water level on the low-lying properties. This study presents a preliminary analysis of the sediment budget across the Swartvlei estuary mouth. The objective of this study was to identify the various sediment contributory factors and to estimate the quantities that each individually contributed towards the defined sediment budget.
AFRIKAANSE OPSOMMING: Die Swartvlei meer en see monding is geleë aan die kaapse suidkus van Suid- Afrika. Dit vorm deel van die kern bewarings area van die Wilderness Nationale Park. Die Swartvlei sisteem bestaan uit twee verbinde, kern dele nl: Swartvlei meer en estuarium. Vir die afgelope twee dekades is hierdie area onder die noue toesig van SANParke as gevolg van die belangrikheid van die area met betrekking tot toerisme en ekologie. Daar is ook menigde laag liggende eiendomme aan die oewers, wat baie sensitief is vir watervlak stygings. Die optimum water vlakke benodig vir die uitskuring van die gety monding het ook implikasies vir die laag liggende eiendome en vereis noukeurige monitering. ‘n Voorlopige analise van die sediment begroting rondom die gety monding word deur hierdie studie voorgelê.
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Raineault, Nicole A. "Effects of bulkheads on estuarine beach swash zone processes and characteristics." 2008. http://hdl.rutgers.edu/1782.2/rucore10001600001.ETD.17376.
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Garcia, Tigreros Fenix. "The Combined Effect of Ocean Acidification and Euthrophication on water pH and Aragonite Saturation State in the Northern Gulf of Mexico." Thesis, 2013. http://hdl.handle.net/1969.1/149421.
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Rising atmospheric carbon dioxide (CO2) concentrations are increasing the rate at which anthropogenic CO2 is accumulating in the ocean, and thereby acidifying ocean water. However, accumulation of anthropogenic CO2 is not the only process affecting coastal oceans. Anthropogenic inputs of nutrients to coastal waters can result in massive algal blooms, a process known as eutrophication. Microbial consumption of this organic matter depletes bottom waters of oxygen and increases acidity through the release of CO2. This study assesses the synergistic effect of ocean acidification and eutrophication in the coastal ocean using data from six cruises to the northern Gulf of Mexico. In addition, this study investigates the effect of the 2011 Mississippi River flood on coastal pH and aragonite saturation states.
Data from a model simulation using data collected from the northern Gulf of Mexico indicates that eutrophication is contributing to acidification of subsurface waters and plays a larger role than acidification from atmospheric CO2 uptake. Furthermore, results from the model simulation show that the decrease in pH since the industrial era is 0.04 units greater than expected from ocean acidification and eutrophication combined. The additional decrease was attributed to the reduced buffering capacity of the region and may be related to the uptake of atmospheric CO2 into O2-depleted and CO2-enriched waters, the addition of atmospheric CO2 into O2-rich and CO2-poor waters, the input of CO2 via respiration into waters in equilibrium with high atmospheric CO2, or a combination of all three processes.
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Rubio, Zuazo Ana Maria. "Environmental influences on the sustainable production of the Sydney rock oyster Saccostrea glomerata : a study in two southeastern Australian estuaries." Phd thesis, 2007. http://hdl.handle.net/1885/49349.
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There has been a continuous decline in both the production and general performance of the SRO in NSW estuaries over the past three decades. The relationship of this decline to both environmental and oyster-density related factors are assessed in this thesis. This question has been examined at different scales: a large scale that compares two different estuaries (Clyde and Shoalhaven Rivers, southern NSW); a regional scale that encompasses variations within an estuary and, at a lease scale that examines processes pertaining to individual or small groups of oysters. ... A set of environmental indices were used to complement the model and to assess the sustainability of the culture system. The combined indices indicated that while the ecological carrying capacity of the Clyde was exceeded the production capacity at an estuarine scale was not. On the lease scale, density experiments showed that while growth was not reduced as a result of current stocking densities, the condition index was significantly affected.
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Yang, Wen-Bin, and 楊文彬. "Investigation on the Characteristics of GHGs Emitted from Industrial Wastewater Treatment Processes and Natural Estuarine Wetlands by In-situ Continuous Monitoring Technology." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/x85k75.
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博士國立中山大學
環境工程研究所
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In the context of global warming and climate change, greenhouse gas (GHG) emission has received a considerable attention for the past decades. Of many natural GHG sources, wetland plays an important role in modulating the concentrations of GHGs in the atmosphere. This study aims to continuously monitor the emission of greenhouse gases (CO2, CH4, and N2O) from a constructed wetland. A self-designed dynamic floating chamber was applied to collect GHGs through a Teflon tube connected to the top of the chamber, and in-situ monitored the concentrations of GHGs with a non-dispersive infrared (NDIR) monitor to continuously measure GHG emissions, estimated its CO2 equivalent (CO2-e), and investigated the seasonal variation of GHGs. This study further correlated GHGs and water quality, and combined GHG data and net primary production data to understand GHG emission from a natural estuarine wetland and a wastewater treatment plant. The temporal variation of greenhouse gas (GHG) emission from petrochemical and integrated industry wastewater treatment plants (WWTP) was then investigated. Two approaches including an in-situ continuous monitoring and a typical grab sampling methods were further compared. The in-situ continuous monitoring method provided more detailed information regarding the temporal variation of GHG concentration. A sufficient sampling frequency (e.g., once every 6 hours) for the grab sampling method is required to effectively resolve the diurnal variation of GHG emission. This study highlights significant diurnal variation of GHG concentration in different wastewater treatment units. Only with proper and reliable sampling and analytical methods, it becomes possible to correctly identify the characteristics of GHG emissions and to develop strategies to curtail the GHG emissions from such an important source in response to regulatory measures and international treaties. This study revealed that N2O was the dominant species responsible for GHG emissions from the WWTPs and the emission factors of CH4, and N2O were higher in the equalization tank and final sedimentation tank compared to other units. We also compared the GHG emission factors of this study with other literatures, showing that the GHG emission factors were much lower than those measured in Netherlands, Australia, and IPCC, but similar to those measured in Japan. Wetland play a crucial role in modulating atmospheric concentrations of greenhouse gases (GHGs). Key factors controlling GHG emission from subtropical estuarine wetlands were investigated in this study, which continuously monitored the uptake/emission of GHGs by/from a subtropical estuarine wetland located in the Minjiang and Zhangjiang estuaries in the coastal region of southeastern China. A self-designed floating chamber was used to collect air samples on-site at three environmental habitats (P. australis, mangrove, mudflats, and river water). Based on its potential to increase global warming, N2O was the main contributor to the total GHG emission, with that emitted from the river water being the most considerable. Tidal water carried onto the marsh had its own GHG content and thus may act as a source or sink of GHGs. However, water quality had a large effect on GHG emissions from the riverwater whereas the tidal water height did not. Both high salinity and large amounts of sulfates in the wetlands explicitly inhibited the activity of CH4-producing bacteria, particularly at nighttime. This study also investigated the seasonal variation of GHG emissions and estimated their overall CO2 equivalent (CO2-e). The GHG emissions were further correlated with water quality to identify which water quality parameters dominated GHG emissions in an estuarine mangrove ecosystem. A positive correlation was found between CO2 emission and water temperature, dissolved oxygen (DO), and total phosphorus (TP) in the riverwater. CH4 emission was positively correlated with TP, DO, and NH4+-N, while N2O emission was significantly positively correlated with DO, TP, and total nitrogen (TN) in the riverwater.