Tesis sobre el tema "Fluvial and estuarine processes"

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

Tropical wetlands such as the Pantanal help regulate global biogeochemical cycles, but climate change is modifying these environments. Controls on environmental changes can potentially be assessed from ancient, well-dated lacustrine sedimentary records. An integrated field and laboratory approach was undertaken to study the limnogeology of Lake Uberaba in the northern Pantanal, and test whether the lake has preserved a reliable record of environmental change in its strata. This study was designed to understand how the basin accumulates sediment and to assess its sensitivity to hydroclimatic variability. The data showed that modern Lake Uberaba is a highly dynamic, freshwater fluvial-lacustrine basin. Modern lake floor sediments are largely siliciclastic silts, with limited organic matter content and abundant sponge spicules. This sedimentary composition reflects the lake’s open hydrology and well-mixed water column. Limited data from sediment cores indicates that Lake Uberaba may have formed ~1760 CE, following an abrupt transgression over an oxidized floodplain depositional environment. The stratal contact between lacustrine and floodplain deposits suggests the presence of an erosional unconformity, the timing and duration of which remains unknown. The environmental change favoring lake formation appears to be linked to increased effective precipitation provided by the Intertropical Convergence Zone (ITCZ) in the northern Pantanal.

Doutoramento em Física
O 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 s􀀀1. 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 s􀀀1. 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.

Postglacial rivers are part of the relatively young low-relief landscape system left behind by glaciers. Over time, postglacial rivers are susceptible to both minor and major channel planform changes as the Earth and its newly exposed rivers adjust to new isostatic and geomorphic equilibriums. Those planform changes result in topographic features that are well preserved among the largely unaltered landscape and offer opportunities to learn about the processes that create them. This work focuses on those minor and major planform changes and the resulting landforms, with a focus on processes effecting the glaciolacustrine Red River Valley. Here, three studies were conducted, two regarding minor planform changes and one focusing on major planform changes. Studies included in this work regard 1) the spatial distribution of meander cutoffs and meander cutoff relief on the Red River, 2), avulsion timing and length resulting from isostatic tilting and 3) mobile river ice and bank interaction frequency, locations, and erosion in meandering rivers. Results show that rivers develop meander cutoffs that faster in areas where geologic materials are more easily eroded and their relief shows a positive relationship with the rate of river incision. Major channel path changes (avulsions) in the presence of isostatic tilting were found to be most frequent soon after river establishment while rates of isostatic rebound are high enough to outpace channel incision. River ice was found to most frequently interact with the outer banks of channels with long, tight bends and high sinuosity, potentially contributing to the meandering process. From these results it can be interpreted that postglacial rivers were highly dynamic early in their history and have stabilized over time, with most of the changes occurring in areas with more erodible alluvium. Presently, rivers undergo most of their changes during the spring thaw when mobile river ice is impacting the banks, with sinuous river reaches impacted most frequently by mobile river ice.
North Dakota Water Recourses Research Institute (ND WRRI) Fellowship Program

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 (PS_Max) 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.

Mestrado em Ciências do Mar e das Zonas Costeiras
Maputo Bay is a tidally-energetic embayment in Mozambique, influenced by strong rainfall and associated river runoff during the wet season. Previous investigations have suggested the arrestment of the freshwater plume related to high mixing during spring tide, eroding stratification and preventing an efficient exchange with the shelf due to the hampering of density currents. It was suggested that, with decreasing mixing towards neap tide, the bay would re-stratify, releasing the estuarine plume. The objective of this dissertation was to find out whether and under which conditions this arrestment of the estuarine plume occurs in Maputo Bay. A 3-dimensional hydrodynamic model was applied to the bay, improving a previously published model through vertical and temporal refinement and recalibration. It is shown that now the model reproduces more accurately the semidiurnal and fortnightly stratification-mixing cycles occurring during the wet season. However, the model still predicts salinities lower than those found in observations. Uncertainties increase towards the mouth of the Maputo River, for which only modelled river flow data was available to force the bay dynamics, indicating this input as a possible source of the underestimation of salinity. The effect of varying river discharges, varying timings of discharge as well as varying discharge ratios on flushing times was investigated through a set of experiments of varying Maputo and Incomati river flows as well as timings of discharge during the spring-neap cycle. The results suggest that when no discharge or a small discharge is introduced, flushing times are smallest during spring tide, when barotropic forcing is strong. Largest flushing times are found approximately 40 hours before neap tide, when tidal forcing is relatively weak. Flushing times for model runs with larger discharge were smaller due to the addition of flushing from river water. Here, flushing times were especially small during neap tide, when the decreased tidal mixing lead to stratification through which a classical estuarine circulation could develop, leading to an efficient bay-shelf exchange. Maximum flushing times for high-discharge runs during wet season were found for spring tide. Shelf-bay exchange was most efficient when the discharge of the Maputo River was larger than the discharge of the Incomati River, due to its location opposite the bay opening, thus influencing a larger area before leaving the bay. Timing of the discharge of the freshwater had only small effects, influencing the amount of mixing induced on the freshwater when first entering the bay. It is concluded that the estuarine plume of Maputo Bay is in fact arrested during spring tide due to the large mixing inhibiting density currents and is released when mixing decreases, inducing stratification and baroclinic circulation. The potential energy stored in the bay is larger for a larger discharge of the Maputo River.
A Baía de Maputo, em Moçambique, é uma baía com marés energéticas, influenciada pelo escoamento dos rios associado a forte precipitação durante a estação húmida. Investigações anteriores têm sugerido que o aprisionamento da pluma de água doce está relacionado com a elevada mistura durante a maré viva, que por sua vez provoca a erosão da estratificação e impede a troca eficiente com a plataforma continental, dificultando o estabelecimento de correntes de densidade. Foi sugerido que com a diminuição da mistura durante a maré morta a baía seria re-estratificada, libertando a pluma estuarina. O objetivo desta dissertação foi averiguar se, e em que condições, este aprisionamento da pluma estuarina ocorre na baía de Maputo. Foi aplicado um modelo hidrodinâmico 3-d para a baía, resultante do melhoramento de um modelo publicado anteriormente, através do refinamento vertical e temporal e recalibração. É demonstrado que agora o modelo reproduz com mais precisão os ciclos de estratificação/mistura semidiurnas e quinzenais que ocorrem durante a estação chuvosa. No entanto, o modelo ainda prevê salinidades inferiores as encontradas em observações. As incertezas aumentam próximo da foz do Rio Maputo, para o qual existem apenas dados de modelos de bacia para forçar o modelo, indicando esta entrada como uma possível causa da subestimação da salinidade. Foi definido um conjunto de experiências de diferentes descargas dos Rios Maputo e Incomati, sendo estes introduzidos no modelo em fárias fases do ciclo da maré. Foi investigado o efeito da variação da duração das descargas fluviais e da proporção do Maputo e do Incomati nos tempos de renovação da água na baía. Os resultados sugerem que quando há uma pequena descarga dos rios, os tempos de renovação são menores durante a maré viva, quando o forçamento barotrópico é forte. Os maiores tempos de renovação encontram-se cerca de 40 horas antes da maré morta. Os tempos de renovação para as corridas com maior descarga são menores devido à adição de descargas de água do rio. Neste caso, os tempos de renovação foram especialmente pequenos durante a maré morta, quando a diminuição da mistura pela maré induz estratificação, criando condições para o desenvolvimento da circulação estuarina clássica, e escoando a baía eficiente. Tempos máximos de renovação para corridas de alta descarga durante a estação chuvosa foram encontrados em condições mistas de maré viva. O intercâmbio entre a baía e a plataforma continental foi mais eficiente para uma maior proporção do Rio Maputo em relação ao Rio Incomati. Este padrão justifica-se pela maior distância da foz do Rio Maputo à entrada da baía. A variação do momento da descarga de água doce em relação à fase da maré tem efeitos pouco significativos (ou pouco relevantes), determinando apenas o grau de mistura que influencia a água doce nas primeiras horas a seguir da descarga. Concluiu-se que existe um aprisionamento da pluma estuarina da Baía de Maputo. Este aprisionamento ocorre durante a elevada mistura de maré viva. A energia potencial armazenada na baía é maior para uma descarga maior do Rio Maputo.

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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A plataforma continental de Pernambuco caracteriza-se por possuir um declive suave, ser estreita, rasa, com águas relativamente quentes, elevada salinidade e por apresentar- se quase inteiramente coberta por sedimentos carbonáticos biogênicos. Esse ambiente é afetado pelo aporte continental, atuando como um receptor final de água, materiais e substâncias, que são transportados pelas descargas dos rios. Desta forma, as regiões costeiras são as mais afetadas pela ação antrópica. O presente trabalho apresentou como objetivo analisar a dinâmica da clorofila-a e parâmetros hidrológicos na plataforma continental de Pernambuco adjacente aos rios Jaboatão e Capibaribe. Foram realizadas coletas bimestrais, abrangendo período chuvoso e de estiagem, em um ponto situado na zona estuarina e quatro outros pontos distribuídos na plataforma. Foram analisados vários parâmetros ambientais como clorofila a, profundidade, salinidade, temperatura, oxigênio dissolvido, taxa de saturação do oxigênio, pH, nutrientes inorgânicos (N- amoniacal, nitrito, nitrato, fosfato e silicato), material particulado em suspensão. A pluviosidade foi a forçante física que mais influenciou na maioria dos parâmetros. No rio Jaboatão, a clorofila-a no estuário variou de 2,89 à 34,71 mg.m-3 e na plataforma de 0,21 à 9,67 mg.m-3 . De acordo com a ACP, a clorofila a esteve diretamente relacionada temperatura, taxa de saturação do oxigênio e inversamente com o pH, transparência da água e salinidade. No porto do Recife, a clorofila a variou entre 13,48 à 145,09 mg.m-3 no estuário e na plataforma a de 0,24 à 19,29 mg.m-3 . A ACP mostrou uma relação direta da clorofila-a com o N-amoniacal, fosfato, transparência e inversa com nitrato e material particulado em suspensão. Nas duas áreas estudadas, houve um aumento da biomassa no período de estiagem. Os pontos da plataforma que mais sofreram influência do deságue foram os mais centrais (P3 e P4), devido ao predomínio dos ventos alísios de sudeste. Após análise das duas áreas, observou-se que os estuários encontram-se poluídos e que no porto do Recife a carga de matéria orgânica é bem mais elevada do que o Jaboatão, provocando maior efeito na plataforma adjacente. Em termo de dispersão de pluma dos rios, no porto do Recife a presença do dique de proteção provoca uma certa perturbação no sentido da corrente, limitando esta pluma, para a parte mais costeira, o que não foi observado na área do Jaboatão.
The continental shelf of Pernambuco is characterized by a gentle slope, it is narrow, shallow, almost entirely covered by biogenic carbonate sediments; the water in the area is warm and has a high salinity. This environment is affected by continental input, and acts as a final receptor of water, materials and other substances that are transported by river discharge. Thus, the coastal regions are the most affected by human action. This study aims to analyze the dynamics of chlorophyll-a and hydrological parameters on the inner shelf of Pernambuco adjacent to the Jaboatão and Capibaribe rivers. The samplings were performed bimonthly at one research site on the estuarine zone and four additional sites distributed on the platform, covering the dry and rainy seasons. Various environmental parameters such as chlorophyll-a, depth, salinity, temperature, dissolved oxygen, oxygen saturation rate, pH, inorganic nutrients (ammonia, nitrite, nitrate, phosphate and silicate), and suspended particulate matter were analyzed. Rainfall was the most influent physical forcing to most parameters. In the Jaboatão River, chlorophyll-a ranged from 2.89 to 34.71 mg.m–3 in the estuary; and from 0.21 to 9,67 mg.m-3 at the platform. According to the PCA , the chlorophyll-a was directly related to temperature, oxygen saturation rate and inversely with the pH, water transparency and salinity. In the Port of Recife, chlorophyll-a ranged from 13.48 to 145.09 mg.m-3 in the estuary and from 0.24 to 19.29 mg.m-3 in the inner shelf. The PCA showed a direct relationship of chlorophyll-a with ammonia, phosphate and water transparency an inverse relationship with nitrate and suspended particulate matter. In both studied areas, there was an increase in biomass in the dry season. In the inner platform , The most central sites (P3 and P4) were the most influenced by river discharge, due to the dominance of trade winds from the southeast. After analysis of the two areas, it was observed that the estuaries are polluted and that, in the Port of Recife, the load organic matter is much higher than in Jaboatão causing greater effect on the adjacent platform. In regarding the river’s plume dispersion in the Port of Recife, the presence of the dike causes some disturbance in the direction of the current. The plume is then limited to the most coastal area. This fact was not observed in the Jaboatão area.

This thesis explores the effects of fluvial processes on Pleistocene lithic artifacts and assemblages in northern Europe. Lithic artifacts are commonly found within fluvial sediments indicating that they have been subject to moving flow. Their incorporation into the bedload may result in changes to morphology and spatial context, thereby obscuring site interpretations. This has been well documented among numerous sites worldwide. This study reports on three experiments aimed at understanding the effects of fluvial processes on lithic artifacts. In the fluvial-field experiment, 456 painted and measured replica lithic artifacts were placed in nine different "scatters" along the River Glenderamackin (UK), where river flow and animal activity were monitored for 18 months. Artifacts were visited at four different times and each time their locations, orientations, and physical conditions were recorded. The results showed that artifact movement depends on lithic morphology and discard location (in the river channel or on the banks), with vegetation and burial playing critical roles in inhibiting transport. Artifact transport also resulted in characteristic edge micro-flaking. In the tumbling barrel experiment, 188 replica lithic artifacts were subjected to an environment simulating the effects of coarse-grained fluvial abrasion. The results showed that artifact lithic abrasion is affected by the amount, size, and lithology of the abrasive sediment as well as the artifact's lithology and shape. The last experiment reports on aspects of fme-grained fluvial abrasion. In this study, 27 artifacts were marked with nine microscopic observation areas and abraded in an annular flume with three different sediment sizes for up to 168 hours. When analyzed with a scanning electron microscope, the results showed that time, and sediment size and the artifact's entrainment mode have varying effects on artifact edge micro-flaking, surface texture, and ridge widths. The implications of these experiments are discussed along with previous experiments and applied to the sites of Happisburgh I (UK), Happisburgh 3 (UK), Pakefield (UK), and Caours (PR), questioning the formation of these sites and indicating that they were subject to post-depositional processes.

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
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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.

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

Rock-avalanches (RAs) are a large (typically > 106 m3) and extremely rapid (30 - >100 m/s) type of landslide. RAs pose a significant hazard as they can runout over long distances and generate secondary hazards such as tsunami and unstable, cross-valley dams. Previous research on the distribution of rock-avalanche deposits (RADs) on the South Island, New Zealand has suggested that there are fewer deposits than would be expected for a seismically active, high-mountain region. This is due to their removal from the sedimentary record (censoring) by fluvial erosion, glacial entrainment, vegetation cover, sub-aqueous occlusion and deposit misidentification. Censoring of deposits skews magnitude-frequency relationships of RA occurrence and hinders hazard planning. This research examines processes acting to fluvially censor RADs on the South Island. 268 known, and 47 possible RADs were identified to provide the first RAD inventory for the entire South Island. The temporal distribution of RADs indicates censoring of the record over the Holocene. >500 year intervals exist between RA events from 12,000 to 2,000 years ago; a more complete record is shown for the last 1,000 to 100 years with intervals of > 50 - < 150 years. The last 100 years shows phases of co-seismic RAD generation, a period of RAD quiescence and a recent increase in aseismic RAD occurrence. The spatial distribution of RADs suggests that the West Coast, Fiordland and Nelson could have experienced fluvial censoring of deposits. The sediment routing characteristics of catchments in these regions, where the majority of rivers have direct pathways from RADs to the ocean, suggest that fluvially reworked RAD material could be stored within alluvial flats and braidplains. Agglomerate grains (microscopic grains which are diagnostic of RAs) were used to identify fluvially reworked RAD material. Grains were detected in dam-breach flood terraces up to 1km downstream of known RADs. Contemporary river sediment samples showed no agglomerate presence, this suggests that 1) agglomerates break down under extended fluvial transport, 2) they are not supplied to river systems outside of flood events, 3) agglomerates become diluted by other river sediment or 4) they become buried in discrete sedimentary layers. In order to investigate the redistribution of coarse RAD material within South Island rivers, a micro-scale flume model was developed. Using ultra-violet sand as a novel analogue for a RAD, the redistribution of material through an idealised South Island catchment could be examined. The model showed that RAD material is deposited in discrete aggradational layers in dam proximal locations. Downstream, the sedimentary signal is rapidly diluted by ordinary river sediment flux. The research shows that the RAD record for the South Island is incomplete and that fluvial censoring is prevalent within the West Coast, Nelson and Fiordland. The agglomerate tracing method can be used to identify the presence of RADs in fluvial systems proximal to RADs but the signal is undetectable after ~1km from the deposit. Both field sampling and flume modelling show that localised flood derived aggradational layers, close to deposit locations, will archive reworked RAD material. These results have important implications for understanding the magnitude and frequency of RADs within New Zealand and other similar high-mountain, tectonically active regions of the globe.

Amazonian tropical forests account for 20-50% of global primary productivity and up to 40% of carbon stored in terrestrial biomass (Phillips et al., 1998). The Amazon is also home to the Earth’s largest river system, accounting for approximately 20% of the world’s total river discharge (Richey et al., 1989). Despite the clear global significance of the Amazon basin, substantial uncertainties remain in terms of both aboveground wood biomass and carbon storage within its extensive forests (Houghton et al., 2001), and the functioning of its river systems, particularly in terms of floodplain inundation (Wilson et al., 2007). This thesis addresses the aforementioned uncertainties through providing new insight into the interaction between fluvial processes and Amazonian floodplain varzea forests, for the Beni floodplain in north east Bolivia. Flood inundation dynamics for the Beni floodplain are quantified through application of a 1D-2D hydraulic model code, with topographical forcing provided through bare earth DEMs derived from the SRTM global elevation dataset (Farr and Kobrick, 2000). Subsequently, in the final part of the thesis, aboveground wood biomass estimates are generated for the Beni floodplain, through extrapolation of plot scale inventory measurements with respect to spatially distributed remote sensing datasets. These estimates are subsequently integrated with modelled flood inundation and maps depicting Beni river channel migration, in order to explore the influence which fluvial processes exert upon aboveground wood biomass storage in varzea forest stands. Overall, results presented within this thesis quantitatively demonstrate that fluvial processes, specifically flood inundation and lateral channel migration, exert significant impacts upon aboveground biomass storage within Beni floodplain forests. Furthermore, as a result of these influences, aboveground wood biomass storage within Beni floodplain forests is substantially lower than would be expected based upon published estimates for varzea forests across the Amazon (Baker et al., 2004; Saatchi et al., 2007). This implies that systematic overestimation of aboveground wood biomass storage for Amazonian varzea forests may constitute a significant source of uncertainty in basin scale biomass estimates.

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.

The dry valley systems in the Kalahari of southern Africa are traditionally considered to have developed as a result of past fluvial activity. However, it has also been suggested that erosion by groundwater processes (sapping and deep-weathering) had an important role in development. This thesis aims to establish the relative role of each of these process areas in mekgacha evolution using a combined geological and geomorphological approach. The study area is restricted to the valley systems of Botswana, eastern Namibia and the Northern Cape Province of South Africa, which can be subdivided into exorcic and endoreic systems directed towards the Orange River and the continental interior, respectively. Field studies, analyses of remotely-sensed imagery and a consideration of network orientation identify evidence for the role of both fluvial and groundwater processes in valley development. However, whilst both groups of processes have operated, the importance of each is suggested to have varied both spatially and temporally. Fluvial processes are indicated by sequences of sediments, relict channels and terrace levels, and appear to have operated most recently. Sapping processes are implied in the formation of certain valley systems, primarily from morphological properties and the presence of relict spring lines. Deep-weathering processes are implicated from the close parallelism of many valleys with geological structures now buried beneath thicknesses of Kalahari Group sediments. Borehole records also indicate deep-weathering of bedrock beneath valleys developed above fracture zones, which is suggested to have operated over the longest timescales. Thin-section studies of duricrusts from valley flanks, together with duricrust profiles and records from lithological boreholes, indicate the role of groundwater in their formation. Results suggest an intrinsic link between duricrust formation and valley development. Geochemical and thin-section analyses of duricrusts further suggest that previous considerations of the palaeoenvironmental significance of Kalahari silcretes based upon TiO2 levels may not be wholly appropriate.

In the past decade there has been a call for integrated studies that examine the interaction of fluvial and aeolian processes (Belnap et al., 2011; Bullard and Livingstone, 2002). In this study, we examined the role of land-use, weather, and soil type on the flux of aeolian material into dry washes on the Colorado Plateau in central Utah, USA, and western Colorado, USA. Our goal was to quantify the impact of individual deposition and erosion events by correlating weather and land-use data with a combination of measurement methods including dust collection via dust traps, GPS surveying, and close-range photogrammetry. Our data suggest that there is an interaction between these processes and that seasonality and land-use play a large role in determining the strength of this interaction. Particularly, high land-use and dry, windy conditions were most conducive to the surface movement of sediment and subsequent removal of that sediment by fluvial processes.

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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Rivers are important agents working in the sculpturing of relief, through its high transport capacity of sediments originary from slopes and marginal erosion. The modeling occurs through the processes of erosion and deposition of sediments, which depend on variables such as lithological composition, slope, and flooding. The processes that originate topographic forms are widely described in the literature of alluvial-bed rivers, however little is known about the occurrence of these forms in mixed bed channels (alluvial-rock) and bedrock channel. In this context, this research aims to describe the topographic forms of the valleys on the Cascavel Plateau. The method for the recognition of these forms is the topographic mapping of cross sections in different parts of the channel located at the top, middle and lower course. The mapping is performed with a set level and optical sights. Were mapped four fluvial channels, two channels in areas with altimetric elevations below 400 meters, and two other channels with elevations above 700 meters. The channels have floodplains with varying lengths. Topographic forms were found as dikes, point bars, flood inundation basins, pools and riffles. The data collected show strong channel incision in the sections corresponding to the upper parts of the channels, and that in the course stretches of low flood plains are well developed. Channel meandering is a characteristic feature of the Cascavel Plateau. The formation of point bars is directly associated with the channel marginal erosion, whereas the dikes are the result of sediment settling. The pool-riffle sequences occur by the reduction of the flow velocity in some places, and, in others, by the presence of woody debris. In some parts of the river where are rock outcrop was observed the formation of pot-holes
Os rios são importantes agentes atuando na esculturação do relevo por meio da sua alta capacidade de transporte de sedimentos originários das vertentes e dos processos de erosão marginal. A modelagem ocorre através dos processos de erosão e deposição de sedimentos, que dependem de variáveis como composição litológica, declividade e cheias. Os processos que originam as formas topográficas são descritos vastamente na literatura sobre rios de leito aluviais, no entanto pouco se sabe sobre a ocorrência dessas formas em canais de leitos mistos (aluviais-rochosos) e leitos rochosos. Nesse contexto esta pesquisa objetiva a descrição das formas topográficas de fundos de vale no Planalto de Cascavel. O método para o reconhecimento dessas formas topográficas consiste no mapeamento de seções transversais em trechos distintos do canal localizados no alto, médio e baixo curso. O mapeamento é realizado com um conjunto de nível ótico e mira. Foram mapeados quatro canais fluviais, sendo dois canais em áreas com cotas altimétricas inferiores a 400 metros e, outros dois canais com cotas superiores a 700 metros. Os canais apresentam planícies de inundação com extensões variadas. Foram encontradas formas topográficas como diques, barras em pontal, bacias de inundação, soleiras e depressões. Os dados coletados mostram que há forte incisão do canal nos trechos correspondentes ao alto curso dos canais, e, que nos trechos de baixo curso as planícies de inundação são bem desenvolvidas. O meandramento de canais é uma característica do Planalto de Cascavel. A formação de barras em pontal está associada diretamente a erosão marginal, enquanto que os diques são resultantes da decantação de sedimentos. As sequências de soleiras-depressões ocorrem pela diminuição da velocidade do fluxo em alguns trechos, e, em outros, pela presença de detritos lenhosos. Nos trechos rochosos onde há afloramento rochoso foi observada a formação de marmitas

Spawning salmon depend on fluvial processes to maintain the bed texture of gravel bedded rivers as suitable spawning and incubation habitat. The coarse texture of a gravel bed is maintained by flow strengths capable of moving the gravel and removing fine sediments, thereby providing loose substrate that enhances its ability to conduct flow (i.e., its hydraulic conductivity). The flow strength that corresponds to the beginning of movement (i.e., entrainment) of a grain on a gravel bed is variable and, therefore, it needs to be measured to predict flow levels capable of bed texture maintenance. Lower flows can deliver fine sediment, which may accumulate in the gravels overlying salmon nests (i.e., redds) reducing the hydraulic conductivity and impairing salmon embryo development. I examine these processes to explain the variability in (i) the rate of change in the proportion of a gravel size fraction entrained as a function of flow strength and (ii) the rate of decrease in hydraulic conductivity as a function of the cumulative transport of fine sediment that depends on flow level.

I used tracer gravel and cobble grains and a two dimensional flow model to determine the flow strengths capable of gravel bed entrainment using binary plots of the occurrence or absence of tracer movement to approximate the fraction of the bed sediment entrained as a logistic function of increasing flow strength. The method provides an approximation of the flow strength capable of entraining the least resistant through the most resistant grains, thereby providing a new method to approximate the flow strength that is capable of fully entraining the bed. The results are confirmed by comparing the measurements of two study sites.

To measure the resistance of individual gravel and cobble grains to downstream movement, I used force gages and a theoretical force balance model that incorporates the frictional resistance of a grain and the lift and drag forces applied by stream flow. I measured the frictional resistance of grains at six sites with different morphologies to evaluate influences on grain resistance. Grain resistance varied depending on the grain size and sorting, amount of infiltrated sand, streamwise position along a gravel bar, and degree of fluctuation in the flow strength. The force balance model predicts that the dimensionless instantaneous flow strength capable of entraining a given proportion of a relative grain size varies along a bar. I tested the force balance model predictions by comparison with the tracer measurements from the tracer study. The differences between the force balance predictions and the tracer entrainment measurements are due to the definition of the flow strength as the time-averaged value from the 2D flow model and the instantaneous value from the force balance model. Adjusting the force balance model predictions by a simple factor that quantifies their difference and that corresponds with an index describing the fluctuations of the instantaneous flow strength about its time-averaged value produces agreement with the tracer measurements. This adjustment to force gage measurements from two sites on opposite limbs of a bar indicates that the time-averaged dimensionless flow strength capable of entraining a given proportion of a relative grain size is constant along a bar.

I constructed artificial redds at five sites to monitor changes in hydraulic conductivity and sand accumulation with cumulative bed load transport. I applied two backfill treatments to examine the effects of the presence and absence of grains smaller than 6.4 mm. Hydraulic conductivity varies temporally due to sand deposition and spatially due to the initial sand content of the backfill and the local sediment supply rate. The rate of change in hydraulic conductivity as a function of increasing cumulative transport is statistically significant but does not differ between backfill treatments or with location. I predicted the effect of flow on egg survival using an empirical relationship between hydraulic conductivity and egg survival with results that indicate hydraulic conductivity is dependent on sediment transport rate as a function of flow rate.

This work provides additional understandings of the relationship between flow and bed texture maintenance processes and useful tools for managing gravel bed rivers.

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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A evolução geoquímica de sedimentos estuarinos próximos à embocadura do rio Timbó é abordada em perfil de sedimentos de fundo, atingindo o início do século XIX. Com base em datações 210Pb a transição séculos XIX/XX é atingida no intervalo 51-54cm. Os sedimentos, pelíticos, mostram dominância de fração carbonática bioclástica (~ 50% do sedimento total), sobretudo planctônica, diminuindo gradualmente no sentido do topo. A taxa de sedimentação linear média é de 3,9 mm/ano no século XX, de 6,7 mm/ano na transição entre os séculos XIX/XX, e de 3,6 mm/ano no século XIX. A evolução industrial, o desenvolvimento de novas tecnologias, e o forte crescimento populacional (segunda metade do século XX) são as principais forçantes antrópicas que modificaram as características hidrodinâmicas e geoquímicas da bacia hidrográfica nos últimos 210 anos. Apesar da reduzida capacidade de complexação iônica destes sedimentos, foi possível evidenciar, da base para o topo, marcos geoquímicos históricos: a) Evento Krakatoa – 1883; b) Fase regional de devastação da mata atlântica – transição séculos XIX/XX, com duração de pelo menos 15 anos; c) Advento de motores movidos a combustíveis, com adição de Pb-tetraetila - transição décadas 20/30; d) Generalização de práticas agrícolas regionais com fertilizantes industriais fosfáticos – transição décadas 50/60; e) Aumento generalizado e progressivo em teores de MP até os dias atuais – transição décadas de 60/70. O status ambiental revela-se contaminado em As (desde o século XIX), em Cr (desde os anos 90 do século XX), e deverá estar comprometido em Hg, nos próximos 25 anos.
The geochemical evolution of estuarine sediments near the mouth of the river Timbó is investigated from bottom sediments profile, reaching the early nineteenth century. Based on 210Pb dating the transition XIX / XX is reached at the level 5154cm. The sediments are pelites that show dominance of bioclastic carbonate fraction (~ 50% of total sediment), particularly planktonic, who decreases gradually towards the top. The linear sedimentation rate shows an average of 3.9 mm/year along the 20th century, 6.7 mm/year in the transition between the 19th/20th centuries, and 3.6 mm/year in the 19th century. The industrial revolution, the development of new technologies, and the strong population growth (second half of 20th century) are the main anthropic forcing that changed the hydrodynamic and geochemical behavior of the basin in the last 210 years. Despite the low possibility of ionic complexation of these estuarine sediments the following historic geochemical markers were featured, from bottom to top: a) Krakatoa event - 1883; b) stage of devastation of the tropical rainforest - transition XIX/XX centuries , remaining at least along 15 years; c) advent of fuel-powered engines with addition of tetraethyl-Pb - transition decades 20/30; d) generalization of regional agricultural practices using industrial phosphatic fertilizer - transition decades 50/60; e) general and progressive increase in levels of MP to the present day - transition decades 60/70. The environmental status is indicated as Ascontaminated (since the 19th century), Cr-contaminated (since the 90’s of 20th century), and should be identical for Hg in the next 25 years.

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O rio Paraná, em seu trecho natural, possui padrão multicanal caracterizado por canais secundários de diferentes ordens, separando diversas ilhas e barras fluviais. As barras fluviais são formas semi-submersas associadas à disponibilidade de sedimentos e a um dinamismo temporal cujas dimensões são controladas pelo fluxo e pela profundidade. Neste estudo, pretende-se compreender os processos que promovem a formação, desenvolvimento e movimentação de uma barra de soldamento situada junto à ilha Santa Rosa, no rio Paraná, município de Porto Rico - PR. Para alcançar os objetivos propostos, foram realizados levantamentos de parâmetros hidráulicos, morfométricos e granulométricos. Nos dados levantados dos parâmetros hidráulicos, verificou-se que a presença da ilha Santa Rosa, juntamente com barra fluvial, divide o canal em dois setores de dinâmica hidráulica e sedimentar distintas. O canal principal conduz a maior parcela da vazão, é mais energético, enquanto o canal secundário apresenta valores inferiores nestes dois parâmetros. A separação do fluxo também acarreta na formação de correntes divergentes à direção principal do canal, favorecendo a diminuição da velocidade e, consequentemente, a deposição de sedimentos no entorno da ilha Santa Rosa. Averiguou-se que a morfologia da barra está diretamente vinculada às flutuações de vazão do rio Paraná: em período de águas altas há maior retrabalhamento da forma, já no período de águas médias, esta se preservou parcialmente, inclusive com afloramento em parte. Quanto aos sedimentos, as partículas de diâmetro fino distribuem-se em locais de maior velocidade de fluxo e profundidade (talvegue) em ambos os períodos analisados As partículas de diâmetro médio a grosso encontram-se no período de águas altas distribuídas pela área estudada; já no período de águas médias, estes sedimentos...
The Paraná River, in its natural stretch, has a multichannel pattern characterized by secondary channels of different orders, which separates several islands and bars. The bars are forms semi-submerged associated with the availability of sediment and a temporal dynamic, whose dimensions are controlled by the flow and depth. This study intends to understand the processes which promote formation, development and movement of the annexation bar associated to the Santa Rosa Island, located on Paraná River, near to Porto Rico - PR. To achieve the proposed aims, surveys were carried out in hydraulic, morphometric and granulometric parameters. In the data hydraulic parameters survey it was found that the presence of Santa Rosa Island along with bar divides the river channel in two sectors of distinct dynamic hydraulic and sediment. The main channel leads to a higher portion of the flow, it is more energetic, while the secondary channel has lower values in these two parameters. The separation of the flow also causes the formation of divergent currents towards the main channel, favoring the decrease in velocity and consequent deposition of sediments near to Santa Rosa Island. It was found that the morphology of the bar is directly linked to fluctuations in the flow of the Paraná River, during periods of high water there is more reworking, since in this average water period partially preserved its shape, emerging in part. As for sediment, the fine diameter particles are distributed in areas of higher flow velocity and depth (thalweg) in both analyzed periods. From medium to coarse diameter particles are, in the high-water period, distributed in the studied area, although in the average water period these sediments are located in low flow velocity and depth (Bar and Secondary Channel). Specific stream power and shields parameter values are larger in the main channel in both periods, indicating... (Complete abstract click electronic access below)

Resumo: O rio Paraná, em seu trecho natural, possui padrão multicanal caracterizado por canais secundários de diferentes ordens, separando diversas ilhas e barras fluviais. As barras fluviais são formas semi-submersas associadas à disponibilidade de sedimentos e a um dinamismo temporal cujas dimensões são controladas pelo fluxo e pela profundidade. Neste estudo, pretende-se compreender os processos que promovem a formação, desenvolvimento e movimentação de uma barra de soldamento situada junto à ilha Santa Rosa, no rio Paraná, município de Porto Rico - PR. Para alcançar os objetivos propostos, foram realizados levantamentos de parâmetros hidráulicos, morfométricos e granulométricos. Nos dados levantados dos parâmetros hidráulicos, verificou-se que a presença da ilha Santa Rosa, juntamente com barra fluvial, divide o canal em dois setores de dinâmica hidráulica e sedimentar distintas. O canal principal conduz a maior parcela da vazão, é mais energético, enquanto o canal secundário apresenta valores inferiores nestes dois parâmetros. A separação do fluxo também acarreta na formação de correntes divergentes à direção principal do canal, favorecendo a diminuição da velocidade e, consequentemente, a deposição de sedimentos no entorno da ilha Santa Rosa. Averiguou-se que a morfologia da barra está diretamente vinculada às flutuações de vazão do rio Paraná: em período de águas altas há maior retrabalhamento da forma, já no período de águas médias, esta se preservou parcialmente, inclusive com afloramento em parte. Quanto aos sedimentos, as partículas de diâmetro fino distribuem-se em locais de maior velocidade de fluxo e profundidade (talvegue) em ambos os períodos analisados As partículas de diâmetro médio a grosso encontram-se no período de águas altas distribuídas pela área estudada; já no período de águas médias, estes sedimentos... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: The Paraná River, in its natural stretch, has a multichannel pattern characterized by secondary channels of different orders, which separates several islands and bars. The bars are forms semi-submerged associated with the availability of sediment and a temporal dynamic, whose dimensions are controlled by the flow and depth. This study intends to understand the processes which promote formation, development and movement of the annexation bar associated to the Santa Rosa Island, located on Paraná River, near to Porto Rico - PR. To achieve the proposed aims, surveys were carried out in hydraulic, morphometric and granulometric parameters. In the data hydraulic parameters survey it was found that the presence of Santa Rosa Island along with bar divides the river channel in two sectors of distinct dynamic hydraulic and sediment. The main channel leads to a higher portion of the flow, it is more energetic, while the secondary channel has lower values in these two parameters. The separation of the flow also causes the formation of divergent currents towards the main channel, favoring the decrease in velocity and consequent deposition of sediments near to Santa Rosa Island. It was found that the morphology of the bar is directly linked to fluctuations in the flow of the Paraná River, during periods of high water there is more reworking, since in this average water period partially preserved its shape, emerging in part. As for sediment, the fine diameter particles are distributed in areas of higher flow velocity and depth (thalweg) in both analyzed periods. From medium to coarse diameter particles are, in the high-water period, distributed in the studied area, although in the average water period these sediments are located in low flow velocity and depth (Bar and Secondary Channel). Specific stream power and shields parameter values are larger in the main channel in both periods, indicating... (Complete abstract click electronic access below)
Orientador: José Cândido Stevaux
Coorientador: Mario Luis Assine
Banca: Paulo Fernando Soares
Banca: Antônio Roberto Saad
Mestre

Excessive erosion and fine sediment delivery to river corridors and receiving waters degrade aquatic habitat, add to nutrient loading, and impact infrastructure. Understanding the sources and movement of sediment within watersheds is critical for assessing ecosystem health and developing management plans to protect natural and human systems. As our changing climate continues to cause shifts in hydrological regimes (e.g., increased precipitation and streamflow in the northeast U.S.), the development of tools to better understand sediment dynamics takes on even greater importance. In this research, advanced geomatics and machine learning are applied to improve the (1) monitoring of streambank erosion, (2) understanding of event sediment dynamics, and (3) prediction of sediment loading using meteorological data as inputs. Streambank movement is an integral part of geomorphic changes along river corridors and also a significant source of fine sediment to receiving waters. Advances in unmanned aircraft systems (UAS) and photogrammetry provide opportunities for rapid and economical quantification of streambank erosion and deposition at variable scales. We assess the performance of UAS-based photogrammetry to capture streambank topography and quantify bank movement. UAS data were compared to terrestrial laser scanner (TLS) and GPS surveying from Vermont streambank sites that featured a variety of bank conditions and vegetation. Cross-sectional analysis of UAS and TLS data revealed that the UAS reliably captured the bank surface and was able to quantify the net change in bank area where movement occurred. Although it was necessary to consider overhanging bank profiles and vegetation, UAS-based photogrammetry showed significant promise for capturing bank topography and movement at fine resolutions in a flexible and efficient manner. This study also used a new machine-learning tool to improve the analysis of sediment dynamics using three years of high-resolution suspended sediment data collected in the Mad River watershed. A restricted Boltzmann machine (RBM), a type of artificial neural network (ANN), was used to classify individual storm events based on the visual hysteresis patterns present in the suspended sediment-discharge data. The work expanded the classification scheme typically used for hysteresis analysis. The results provided insights into the connectivity and sources of sediment within the Mad River watershed and its tributaries. A recurrent counterpropagation network (rCPN) was also developed to predict suspended sediment discharge at ungauged locations using only local meteorological data as inputs. The rCPN captured the nonlinear relationships between meteorological data and suspended sediment discharge, and outperformed the traditional sediment rating curve approach. The combination of machine-learning tools for analyzing storm-event dynamics and estimating loading at ungauged locations in a river network provides a robust method for estimating sediment production from catchments that informs watershed management.

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.

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.

O estudo de bacias hidrográficas no meio tropical úmido, tem adquirido grande importância nas últimas décadas, devido a crescente demanda por planejamento de recursos hídricos. Entretanto, muitos desses trabalhos têm confundido o conceito de bacias hidrográficas, acreditando ser esta, uma mera rede de canais interconectados que formam a hidrografia dos terrenos, portanto, tomando-a como simples unidade cartográfica de estudo. Este fato tem banalizado em muito o uso de conceitos relacionados aos estudos de bacias, provocando sérios equívocos nas produções acadêmicas atuais. Partindo do princípio de que as bacias hidrográficas são espaços territoriais de circulação vertical e horizontal dágua, tendo a rede interconectada de canais, como um dos seus principais elementos, que escolhemos a bacia hidrográfica do Rio Benevente para estudo da relação entre a dinâmica fluvial desta e os seus condicionantes estruturais e morfológicos. Fundamentado no método da associação e indeterminação geomorfológica de Leopold e Langbein (1970), e, através de informações oriundas dos procedimentos técnico-operacionais de compartimentação geomorfológica e compilação de dados de parâmetros hidrográficos, foi possível descobrir que os sub-sistemas de drenagem que compõem a hidrografia total da bacia, evoluem condicionados por litoestruturas cristalinas e tectônicas do proterozóico, portanto, de organização antiga, e, que, aparentemente, demonstram não sofrer reativações modernas, a ponto de intervir na evolução dos sub-compartimentos de relevo regionais e na evolução hidrográfica da rede de canais. Chega-se desta forma, à conclusão de que os processos de encaixamento da drenagem, capturas fluviais, seccionamento de litoestruturas, gênese de knickpoints e evolução dos perfis longitudinais fluviais estão associados à dinâmica de processos geomórficos diferenciais, sob litoestruturas de forte natureza anisotrópica e complexa organização geotectônica. Fato que responde pela diversidade de sub-compartimentos de relevo e configuração evolutiva dos sistemas fluviais de dinâmicas diferenciais.
The study of watersheds in the humid tropical environment, has acquired great importance in recent decades due to growing demand for water resources planning. However, many studies have confused the concept of watersheds, believing that this was simply a network of interconnected channels that form the hydrography of the land, thus making it as simple cartographic unit of study. This commonplace is the use of concepts related to the studies of basins, causing serious confusion in the current academic productions. Assuming that the basins are territorial spaces of vertical and horizontal movement of water, the interconnected network of channels, as one of its main elements, we chose the basin of Rio Benevente to study the relationship between the dynamics of this river and its structural and morphological constraints. Based on the method of the Association and indeterminacy in geomorphologic Leopold and Langbein (1970), and through information from the technical and operational procedures of geomorphological partitioning and compilation of data from hydrographic parameters, could find that the sub-drainage systems that make up the total of the hydrographic basin, driven by evolving litoestruturas crystal and the tectonic proterozóico, therefore, the old organization, and that, apparently, show not suffer reactivations modern as to intervene in the evolution of sub-compartments of regional importance and the evolution of the network of river channels. Enough is thus concluded that the processes to fit the drainage, catch river, sectioning of litoestruturas, gênesis of knickpoints and evolution of longitudinal river profiles are associated with the dynamic of geomorphic processes differential,under litoestruturas of strong anisotropic nature and complex organization geotectônica. Fact responsible for the diversity of sub-compartments of important configuration and evolutionary dynamics of river systems of differential.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
Trees, twigs and leaves fallen inside of the channel, form a significant component of the fluvial environment and natural occurrence in fluvial systems that cut forested areas. All these vegetal materials that are found inside of the channel are called wood debris. The wood debris play a key function in the ecology and geomorphology of channels, being able to affect the processes of the channels in an ample reach: since the hydraulic roughness, retention and sized grain of bed sediments, until the creation of steps and pools, being able to the times to control the standard of the channel and distance and/variation of fluvial features that are basic for the formation of aquatic habitat. In this context, the present research had as objective, to verify the influence of accumulations of wood debris on the morphology and sedimentology of stream bed in the river Guabiroba, Guarapuava, Center-South of the Paraná. The used techniques had included: installation of permanent transversal profiles (to the upstream and downstream of the accumulations) and sections of batimetric measurement, survey of the longitudinal profile and grain sized characterization of bed sediments. The measurement was carried throughout 15 months (December of 2007 the March of 2009) in four sections located in the main course of the river. The rainfall during the measurement allowed to particularizing the occurrence of only one period with rains above average (3 - 4ª Campaign). The results indicate the occurrence of sedimentation in the second and fifth measurement and processes of erosion in the third and fourth measurement. These processes erosive-depositional can in part be attributed to the pluviometric regime, with the periods of high entailed concentration of rains to the erosion of the stream bed and periods of related scarce and not concentrated rains with the deposition of sediments. The analysis of the data allows to establish some consideration: 1) predominance of processes of erosion in the sections of batimetric measurement; 2) bigger rate deposition in downstream cross-sectional profiles of the accumulations; 3) predominance of coarser sediments (gravel medium - sand very coarse) to upstream and finer sediments (gravel fine - sand medium) to downstream; 4) bigger diversity of depths in the immediacy of the accumulations; 5) establishment of riffles by the forced deposition of sediments and pools for the scour of the stream bed.
Árvores, galhos e folhas caídos dentro do canal formam um significativo componente do ambiente fluvial e de ocorrência natural em sistemas fluviais que cortam áreas florestadas. Toda essa carga de material de origem vegetal que se encontra dentro do canal é chamada de detritos lenhosos. Os detritos lenhosos desempenham função chave na ecologia e geomorfologia de canais, podendo afetar os processos do canal em um amplo alcance: desde a rugosidade hidráulica, retenção e grânulometria dos sedimentos de leito, até a criação de degraus e depressões, podendo, às vezes, controlar o padrão do canal e a distância/variação de feições fluviais que são fundamentais para a formação de habitat aquáticos. Num contexto desses, a presente pesquisa teve como objetivo verificar a influência de acumulações de detritos lenhosos sobre a morfologia e a sedimentologia de leito no Rio Guabiroba, município de Guarapuava, mesorregião Centro-Sul do Paraná. As técnicas utilizadas incluíram: instalação de perfis transversais permanentes (a montante e a jusante das acumulações) e seções de monitoramento batimétrico, levantamento do perfil longitudinal e caracterização grânulométrica de sedimentos do fundo. O monitoramento foi realizado ao longo de 15 meses (dezembro de 2007 a março de 2009) em quatro pontos localizados em dois trechos no curso principal do rio. A pluviosidade durante o monitoramento permitiu individualizar a ocorrência de apenas um período com chuvas acima da média (3ª a 4ª campanha). Os resultados indicam a ocorrência de sedimentação na segunda e quinta campanhas e processos de erosão na terceira e quarta campanhas. Esses processos erosivo-deposicionais podem, em parte, ser atribuídos ao regime pluviométrico, com os períodos de alta concentração de chuvas vinculados à erosão do leito e períodos de chuvas escassas e não concentradas relacionados com a deposição de sedimentos. A análise dos dados permite estabelecer algumas considerações: 1) predominância de processos de erosão nas seções de monitoramento batimétrico (Blocos 3D); 2) maior taxa de deposição nos perfis transversais situados a jusante das acumulações; 3) predomínio de sedimentos mais grossos (seixo médio - areia muito grossa) a montante da acumulação do que a jusante (seixo fino - areia média); 4) maior diversidade de profundidades nas imediações das acumulações; 5) estabelecimento de soleiras pela deposição forçada de sedimentos e depressões pela escavação do leito.

Tide-influenced point bars represent a significant proportion of shallow-marine deposits, commonly developed along meandering channels in most backbarrier and estuarine systems. However, sedimentological studies to characterize this type of deposit are still emerging. They often present very heterogeneous internal architectures which development is controlled by the complex flow patterns operating in tidal environments. The study of the sedimentological and morphological characteristics of these features provides better understanding of the hydrodynamic processes that shape coastal systems and control their evolution as well as it contributes to better reservoir potential prediction and production strategy optimization, as tidal point bars may represent hydrocarbon reservoirs in subsurface and their heterogeneous characteristics directly impact reservoir quality. In this study, we investigated six modern tidal point bars located along distinct estuarine tidal channels in Georgia. Using core data, 2D shallow seismic data and current measurements and flow velocity profiles, we discussed the main hydrodynamic controls on sediment transport and distribution, and determined how they affect the morphology, the internal architecture and the sediment distribution within these bars. We confirmed that the influence of fluvial input in tidal channels plays an important role on the development of the morphology and the heterogeneous architecture of point bars as it adds more complexity to the system hydrodynamics, promoting more asymmetric variations in water level fluctuations and huge variations of current velocities. We proved that point bars developed in distinct tide-influenced channels and estuaries, although present very different sedimentary facies distribution, may have sedimentary facies in common, which organization is analogous to surface processes operating at each environment. We demonstrated that differences in tidal asymmetries between the ebb and flood channels produce sedimentological differences between the different parts of the bar. This study showed that tidal point bars present distinct heterogeneous sediment distributions, morphologies and internal architectures that do not conform to the existing theoretical models of fluvial point bars and highlighted that, despite the differences in local hydrodynamic conditions, similarities identified between the different bars permitted us to distinguish the sedimentological responses to regional allogenic events, which can be mistakenly interpreted as sedimentological responses to local autogenic events.

Pesquisas recentes apontam para o fenômeno construtivo de sambaquis fluviais na região do médio Vale do Ribeira de Iguape, São Paulo, mais precisamente em três regiões, Itaoca, bacia do rio Jacupiranguinha e bacia do Juquiá, durante, pelo menos, o período de 9000 anos. O presente trabalho tem por objetivo definir o perfil de um sambaqui fluvial, sítio Moraes (6000-4000 anos a.P.), no município de Miracatu, SP, com a finalidade de criar a compreensão intra-sítio dos processos formativos envolvidos para a elevação desta estrutura monticular, através de diferentes abordagens: distribuição espacial intra-sítio, tecnologia, subsistência, isótopos estáveis, estudo sedimentológico e análise de proporção componencial volumétrico. Os resultados destas análises associados aos dados advindos de outras pesquisas nos permitiram ampliar a discussão sobre o processo formativo do sítio Moraes e abordar a questão sobre as relações genética e cultural entre sambaquieiros fluviais e os demais grupos vizinhos.
Previous research at the Ribeira de Iguape valley, at the southern part of the State of São Paulo, Brasil, has revealed a long cultural sequence (ca. 11 to 1,2 kyBP) characterized by small shellmound sites generally designated as riverine, or fluvial, sambaquis. Besides the conspicuous presence of a terrestrial gastropod (Megalobulimus sp.) shells, these little mounds also share relevant amounts of human burials and similar technological patterns as regards lithic and bone industries, among other compositional elements. The principal aim of this thesis is to describe one of these mounds, Moraes, investigating the cultural and post-depositional formation processes implied on the long duration (6 to 4 kyBP) construction phase of such mound structure and after its abandonment, by means of zooarchaeological, technological, geochemical and isotopic analysis of its various deposits and cultural components therein, as well as their spatial distribution and articulation. This thesis also discusses the cultural and historical relationships of this fluvial shellmound culture with other cultural patterns and populations found at the same and nearby areas.

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.

Aquesta tesis es centra en l’estudi de la transferència d’aigua i sediments des de les àrees font de sediments fins les zones de sedimentació a múltiples escales temporals (des de dades amb una freqüència de cinc minuts fins informació de tot un segle) i espacials (des de vessants fins a conques), i les seves implicacions en la morfologia de la llera de la conca de l’Alt Cinca, una conca de muntanya localitzada al vessant sud dels Pirineus. A escala de micro-conca, les dades d’alta resolució obtingudes durant 5 anys en dos badlands contrastats (0.3 ha cadascun) revelen com la pluja controla els processos erosius associats a l’escolament superficial, m’entre que les baixes temperatures tenen una relació significativa amb els processos de moviments en massa. La morfometria d’aquestes superfícies, conjuntament amb la cobertura vegetal són factors clau que determinen els principals processos geomorfològics i els associats canvis topogràfics. Els principals processos observats han estat seqüències d’Erosió i Sedimentació (Cutting and Filling) i Moviments Gravitacionals (Mass Wasting). Tot i que els badlands tenen un paper important en la producció de sediments, el balanç de sediments de la conca del riu Soto (10 km2) indica que aquestes superfícies no sempre controlen l’exportació de sediments a la sortida de petites conques de muntanya amb caràcter intermitent. Aquest fet és degut a la fluctuació de la connectivitat funcional de la xarxa de drenatge causada per la freqüència i magnitud dels polsos d’aigua i sediments durant crescudes sobtades o flashy. La xarxa de drenatge actua com a font i zona d’emmagatzematge de sediments i es clau per entendre les marcades diferències que hi ha en la proporció del sediment que s’exporta en relació a la producció o també anomenat Sediment Delivery Ratio. Els canvis en els usos de sòl en moltes conques de muntanya constatats des de els anys 50 del segle XX tenen un efecte directe en la generació d’escolament (quantitat i magnitud) i en la producció de sediments. La majoria de la superfície de la conca de l’Alt Cinca (1565 km2) ha sofert aforestació, que ha resultat en una reducció de la connectivitat sedimentaria estructural. La construcció de terrasses afecta la connectivitat molt més que els canvis en la coberta del sòl. Les terrasses generalment redueixen la connectivitat degut a l’establiment de zones planes entre mig de zones en pendent. Contràriament, a una escala més local, les terrasses poden incrementar la connectivitat degut a la convergència de flux produïda per les pròpies estructures, o per la caiguda d’aquestes degut a l’abandonament. La construcció de carreteres modifica el pendent i la xarxa de drenatge, fet que comportarà canvis en la connectivitat estructural, que a la vegada poden afectar els processos erosius en les zones veïnes. Així, els fluxos d’aigua i sediments a la conca de l’Alt Cinca han estat àmpliament modificats durant l’últim segle, amb implicacions directes en la forma de la llera. A més a més, impactes locals derivats de les extraccions d’àrids, construcció d’esculleres i embasaments també han condicionat la dinàmica sedimentaria d’aquest riu, amb un impacte directe sobre la morfologia. Aquesta situació ha generat una metamorfosis de la morfologia del riu en la part baixa de l’Alt Cinca (12 km), canviant d’un patró trenat, molt dinàmic, a un patró més estable amb una tendència cap a canal únic. Els resultats obtinguts indiquen que el tram d’estudi està assolint un nou equilibri morfo-sedimentari imposat pels canvis en els fluxos d’aigua i sediments ocorreguts en el darrer segle, incloent les pertorbacions antròpiques que han modificat la geometria del canal i les característiques morfològiques de la llera. S’han observat un total de tres fases en la seva evolució: abans de l’any 1927, el tram d’estudi es trobava en una situació de quasi-equilibri majoritàriament condicionada per les riuades. Entre l’any 1927 i 2012 el riu s’ha ajustat a les diferents pertorbacions que ha tingut a múltiples escales temporals i espacials. Aquest ajust s’ha portat a terme mitjançant dos canvis contrastats en les característiques morfològiques. Finalment, després de l’any 2012, els resultats indiquen que el riu pot haver assolit de nou un nou equilibri, ajustant-se als fluxos d’aigua i sediment imposats i a la nova configuració del canal. Aquesta tesis presenta innovadors mètodes quantitatius per a l’estudi de la producció de sediments i la transferència entre els diferents compartiments de les conques fluvials. La principal novetat en la majoria dels capítols de la tesis recau en l’elevada resolució, de les dades obtingudes, tant temporal com espacial. Els resultats obtinguts en aquesta tesi permeten entendre millor el funcionament dels sistemes fluvials i la seva evolució, aspectes claus per donar suport en la millora i gestió de conques hidrogràfiques de muntanya.
Esta tesis se centra en el estudio de la transferencia de agua y sedimentos desde las áreas fuente de sedimentos hasta las áreas de sedimentación a múltiples escales temporales (desde datos con una frecuencia de cinco minutos hasta información de un siglo) y espaciales (desde laderas hasta cuencas), y sus implicaciones en la morfología del cauce en la Cuenca del Alto Cinca (vertiente sur de los Pirineos). A escala de micro-cuenca, los datos de alta resolución obtenidos durante 5 años en dos badlands contrastados (0.3 ha cada uno) revelan como la lluvia controla los procesos erosivos asociados a la escorrentía superficial, mientras que las bajas temperaturas tienen una relación significativa con los procesos de movimientos en masa. La morfometría de estas superficies, conjuntamente con la cobertura vegetal, son factores clave que determinan los principales procesos geomorfológicos y los cambios topográficos asociados. Los principales procesos observados han sido secuencias de Erosión y Sedimentación (Cutting and Filling) y Movimientos Gravitacionales (Mass Wasting). Pese a que los badlands tienen un papel importante en la producción de sedimentos, el balance de sedimentos de la cuenca del rio Soto (10 km2) indica que estas superficies no siempre controlan la exportación de sedimentos a la salida de pequeñas cuencas de montaña con carácter intermitente. Esto principalmente se debe a la fluctuación de la conectividad funcional de la red de drenaje causada por la frecuencia y magnitud de los pulsos de agua y sedimentos durante las crecidas súbitas o flashy. La red de drenaje actúa como fuente y zona de almacenamiento de sedimentos, y es clave para entender las marcadas diferencias que hay en la proporción de sedimento que se exporta en relación a la producción o Sediment Delivery Ratio. Los cambios en los usos del suelo en muchas cuencas de montaña constatados desde los años 50 del siglo XX tienen un efecto directo en la generación de escorrentía (cantidad y magnitud) y en la producción de sedimentos. La mayoría de la superficie de la cuenca del Alto Cinca (1565 km2) ha sufrido forestación, que ha resultado en una reducción de la conectividad sedimentaria estructural. La construcción de terrazas afecta la conectividad mucho más que los cambios en la cobertura del suelo. A una escala más local, las terrazas pueden incrementar la conectividad debido a la convergencia de flujo producida por las propias estructuras, o por la caída de estas debido a su abandono. La construcción de carreteras modifica la pendiente y la red de drenaje, hecho que comporta cambios en la conectividad estructural, que a su vez pueden afectar a los procesos erosivos en las zonas vecinas. Así, los flujos de agua y sedimento en la cuenca del Alto Cinca han estado ampliamente modificados durante el último siglo, con implicaciones directas en la morfología del canal. Además, impactos locales derivados de las extracciones de áridos, construcción de escolleras y embalses también han condicionado la dinámica sedimentaria de este río, con un impacto directo sobre la morfología. Esta situación ha generado una metamorfosis de la morfología del río en la parte baja del Alto Cinca (12 km), cambiando de un patrón trenzado, muy dinámico, a un patrón más estable con una tendencia hacia el canal único. Los resultados obtenidos indican que el tramo de estudio está alcanzando un nuevo equilibrio morfo-sedimentario impuesto por los cambios en los flujos de agua y sedimentos ocurridos durante el último siglo, incluyendo las perturbaciones antrópicas que han modificado la geometría del canal y las características morfológicas del cauce. Se han observado un total de tres fases en su evolución: antes de 1927, el tramo de estudio se encontraba en una situación de casi-equilibrio, mayoritariamente controlada por las crecidas. Entre el año 1927 y 2012 el río se ha ajustado a las diferentes perturbaciones que ha tenido a múltiples escalas temporales y espaciales. Este ajuste se ha llevado a cabo mediante dos cambios contrastados en las características morfológicas. Finalmente, después del año 2012, los resultados indican que el río puede haber alcanzado un nuevo equilibrio, ajustándose a los flujos de agua y sedimento impuestos y la nueva configuración del canal. Esta tesis presenta innovadores métodos cuantitativos para el estudio de la producción de sedimentos y la transferencia entre los diferentes compartimentos de las cuencas fluviales. La principal novedad en la mayoría de los capítulos de la tesis recae en la elevada resolución de los datos obtenidos, tanto temporal como espacial. Los resultados obtenidos en esta tesis permiten entender mejor el funcionamiento de los sistemas fluviales y su evolución, aspectos clave para dar soporte y apoyo en la mejoría y gestión de cuencas hidrográficas de montaña.
This thesis focusses on the study of water and sediment transfer from sources to sinks at multiple temporal (from 5-min data to a century data sets) and spatial (from slope to catchment scales) scales and their implications for channel morphology in the Upper Cinca catchment, a mountain catchment located in the Southern Pyrenees. At the micro-catchment scale, our 5-year High Resolution Data Set of two contrasted badlands (around 0.3 ha each) reveal as rainfall control overland-surface flow processes while low temperatures have a significant relation with mass movement-based processes. Morphometry together with vegetation cover are key factors determining main geomorphic processes and associated topographic changes. Main observed geomorphic processes were Cutting and Filling and Mass Wasting. Although badlands may have an important role on sediment production, the 2-year sediment budget of the Soto catchment (10 km2) indicates that badlands do not always control the export of sediments at the outlet of small intermittent mountain catchments. This is mainly due to the fluctuation of the functional connectivity of the channel network caused by the frequency and magnitude of water and sediment pulses during flashy floods. The channel drainage network acts as sediment source and sink and it is key to understand marked differences in the Sediment Delivery Ration. Land use and cover in many mountain catchments have been modified since the fifties of the 20th century, having a direct effect on runoff and sediment production. Most of the area of the Upper Cinca catchment (1565 km2) has undergone afforestation, which resulted in a decrease of structural sediment connectivity. Terracing affects connectivity much more than changes in land cover. Terraces generally reduce connectivity due to the establishment of flat areas between slopes and, contrarily, locally, may increase connectivity due the convergence produced by the structures or the collapse of terraces due to abandonment. Road construction, however, modify slope and the drainage network, which leads to changes in connectivity that could affect erosional processes in the neighbouring areas. Thus, water and sediment fluxes through the Upper Cinca are spatially and temporal dynamic and have been dramatically modified in the last century, with direct implications on channel morphology. Additionally, localised disturbances such as gravel mining, channel embankments and dams have also impacted on sedimentary dynamics, thus channel morphology. This situation led to a river metamorphosis, changing from a braided pattern to a more static channel towards a wandering pattern. We hypothesise that the lowermost 12-km reach of the Upper Cinca has reaching a new equilibrium imposed by catchment-scale changes of water and sediment fluxes caused by global changes, but also influenced by localised human-disturbances that modify channel geometry and morpho-sedimentary characteristics. Three phases were identified: before 1927, the reach remained in a quasi-equilibrium state imposed, mainly, by water and sediment supply during flood events. During the period 1927-2012 the river adjusted to the disequilibrium imposed by disturbances acting at different temporal and spatial scales, yielding two contrasted channel states. Finally, after 2012, we hypothesise that the river may be reaching again a new equilibrium, adjusting to the imposed water and sediment fluxes and the new channel configuration. This thesis presents some novel quantitative methods for the study of sediment production and transfer between the different compartments of fluvial catchments. The main transversal novelty in all the methods used in each chapter lies in the high resolution of the data obtained. This comprehensive analysis aids at understanding the functioning of the river system and their evolution based on multiple-scale disturbances, which can help to support integrated watershed management practices or plans.