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1
Alqahtani, Faisal A. "3D seismic geomorphology of fluvial systems." Thesis, Imperial College London, 2010. http://hdl.handle.net/10044/1/6180.
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Fluvial sandstones constitute one of the major clastic petroleum reservoir types in many sedimentary basins around the world. This is especially true in the Tertiary basins of Southeast Asia, which display a wide range of fluvial channel reservoir types. This study is based on the analysis of high-resolution, shallow (seabed to ca. 500 m depth) 3D seismic data which provide exceptional imaging of the geometry, dimension and temporal and spatial distribution of fluvial channels. The Malay Basin comprises a thick (>8 km), rift to post-rift Oligo-Miocene to Pliocene basin-fill. The youngest (Miocene to Pliocene), post-rift succession is dominated by a thick (1-5 km), cyclic succession of coastal plain and coastal deposits, which accumulated in a humidtropical climatic setting. This study focuses on the Pleistocene to Recent (ca. 500 m thick) succession, which comprises a range of seismic facies, mainly reflecting changes in fluvial channel style and gross stratigraphic architecture. The succession has been divided into four seismic units (Unit 1-4), bounded by basin-wide stratal surfaces. Units 3 and 4 have been further divided into two sub-units. Two types of boundaries have been identified: 1) a boundary that is defined by a regionally-extensive erosion surface at the base of a prominent incised valley (e.g. Horizons C.1 and D.1); 2) a sequence boundary that is defined by more weakly-incised, straight and low-sinuosity channels which is interpreted as lowstand alluvial bypass channel systems (e.g. Horizons A, B, C, and D). Each unit displays a predictable vertical change of the channel pattern and scale, with wide low-sinuosity channels at the base passing gradationally upwards into narrow high-sinuosity channels at the top. The wide variation in channel style and size is interpreted to be controlled mainly by the sea-level fluctuations on the widely flat and tectonically-quiescent Sundaland Platform.
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Warwick, Gail L. "The geomorphology and sedimentology of terminal fluvial systems." Thesis, University of Aberdeen, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.487421.
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The geomorphology and sedimentology of terminal fluvial systems. Fluvial systems operating within drylands commonly experience downstream discharge reduction due to infiltration, evaporation and limited tributary inputs. Sediment bodies developed within the distal zones of rivers that do not drain into the sea or a lake (terminal fluvial systems) are currently represented by the terminal fan facies model. This model summarises the development of a distally thinning and fining sedimentary wedge from a coeval network of low sinuosity distributary channels as induced by the sub aerial termination ofchannelised flow under a dryland climate regime.. Extensive review of sediment fan bodies located within modern drylands highlights pronounced disequilibrium between planform character and present ephemeral flow conditions. Out of eighty documented fluvial systems no convincing examples fit the terminal fan model, including two commonly cited analogues used to support this model. In order to fully evaluate the terminal fan concept and redress the current imbalance in modern analogue studies, field work was undertaken to characterise sub aerial fluvial system termination within a single physiographic province - the Basin and Range rift complex of the southwestern U.S.A. Documentation of the potential range in fluvial style and character within this modern dryland environment is provided by the detailed study of seven terminal fluvial systems. Basin and Range terminal fluvial systems demonstrate strong geomorphic form inheritance. Fan landforms observed within medial and distal reaches of these systems predominantly represent relic Late Pleistocene highstand delta bodies into which the modern system is inset. Active terminal reaches operate within basin centre playa environments where shallo~ gradients induce frequent avulsion and the generation of composite lowstand fan bodies located downstream of lateral system confinement. These terminal features record non-coeval channel activity and the dominance of sinuous channel forms. Morphometric trends distinguish a general downstream reduction in channel scale characterised by the development of progressively narrower and shallower channel forms. Channelised flow is maintained within proximal and medial reaches but does not dominate distal reaches where sheetflow discharge is readily attained. Concomitant reductions in channel capacity and competence control the volume and calibre of fluvial material supplied to basinal environments. Progressive downstream thinning is associated with selective deposition and general basinwards sediment fining and sorting. Terminal reaches transport negligible bedload material and display a comparable depositional record to that generated by background playa sedimentation. Identified similarities with the terminal fan model include downstream loss of channel definition, sediment thinning, fining and improved sorting. Conversely, coeval distributive flow is not observed, constituent channels record moderate to high sinuosity and negligible fluvial material reaches basin centre locations. Basin and Range systems are principally responding to streampower reduction controlled primarily by gradient and enhanced by discharge attenuation. Sub aerial termination dominates due to the absence of basin centre lacustrine bodies; a condition forced by limited discharge supply from catchment reaches, compounded by transmission losses and maintained by excessive evaporation from extensive, low elevation flat playa surfaces. In conclusion, fluvial fan landforms generated exclusively from discharge attenuation do not characterise modern dryland environments. Selection of modern analogue systems for use in the interpretation and prediction of ancient fluvial successions must acknowledge the influence of high frequency and high magnitude climate fluctuations upon modern fluvial geomorphology. Key to this is an appreciation of modern processform disequilibrium and the identification of inherited planform characteristics.
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McInally, Alan T. "The reservoir sedimentology of ephemeral fluvial distributary systems." Thesis, Royal Holloway, University of London, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.287122.
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Lo, Edward Limin. "FLUVIAL-LACUSTRINE PROCESSES SHAPING THE LANDFORMS OF THE DISTAL PARAGUAY FLUVIAL MEGAFAN." UKnowledge, 2017. http://uknowledge.uky.edu/ees_etds/54.
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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.
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Grashion, Anton R. "Computer aided analysis of ancient fluvial depositional environments." Thesis, Staffordshire University, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.241509.
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Willams, Neil D. "Form and function of composite particles within fluvial systems." Thesis, University of Exeter, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.425506.
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Cesar, Colmenares Jaime Rafael. "Organic geochemistry and novel isotopic approaches of fluvial-deltaic petroleum systems." Thesis, Curtin University, 2017. http://hdl.handle.net/20.500.11937/59046.
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This thesis re-evaluates the history of fossil fuels in the Dampier sub-Basin, North West Shelf of Australia, from the stage of deposition of land plant debris. It then identifies potential source rock signatures from organic-inorganic interactions during diagenesis (including compounds such as sesquiterpanes and benzonaphthofurans), and explores future perspectives in fluid screening using novel site-specific isotopic parameters for light hydrocarbons. The approaches described herein can be applied to similar petroleum systems worldwide.
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Rowan, John Sibbald. "The sediment-associated transport and redistribution of Chernobyl-derived radiocaesium in fluvial systems." Thesis, University of Exeter, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.277165.
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Gulick, Virginia Claire. "Magmatic intrusions and hydrothermal systems: Implications for the formation of Martian fluvial valleys." Diss., The University of Arizona, 1993. http://hdl.handle.net/10150/186325.
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This dissertation investigates the possible role of hydrothermally driven groundwater outflow in the formation of fluvial valleys on Mars. Although these landforms have often been cited as evidence for a past wanner climate and denser atmosphere, recent theoretical modeling precludes such climatic conditions on early Mars when most fluvial valleys formed. Because fluvial valleys continued to form throughout Mars' geological history and the most earth-like stream valleys on Mars formed well after the decline of the early putative earth-like climate, it may be unnecessary to invoke drastically different climatic conditions for the formation of the earliest stream valleys. The morphology of most Martian fluvial valleys indicates formation by ground-water sapping which is consistent with a subsurface origin. Additionally, many Martian fluvial valleys formed on volcanoes, impact craters, near fractures, or adjacent to terrains interpreted as igneous intrusions; all are possible locales of vigorous, geologically long-lived hydrothermal circulation. Comparison of Martian valley morphology to similar features on Earth constrains valley genesis scenarios. Volumes of measured Martian fluvial valleys range from 10¹⁰ to 10¹³ m³. Based on terrestrial analogs, total water volumes required to erode these valleys range from -10¹⁰ to 10¹⁵ m³. The clustered distribution of Martian valleys within a given terrain type, the sapping dominated morphology, and the general lack of associated runoff valleys all indicate the importance of localized ground-water outflow in the formation of these fluvial systems. An analytic model of a conductively cooling cylindrical intrusion is coupled with the U.S. Geological Survey's numerical ground-water computer code SUTRA to evaluate the magnitude of ground-water outflow expected from magmatically-driven hydrothermal systems on Mars. Results indicate that magmatic intrusions of several 10² km³ or larger can provide sufficient ground-water outflow over periods (several 10⁵ years) required to form Martian fluvial Valleys. Therefore, a vastly different climate on early Mars may not be necessary to explain the formation of the observed Valleys. Martian hydrothermal systems would have also produced long-lived sources of near-surface water; these localized regions may have provided oases for any microbial life that may have evolved on the planet.
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Afolabi, Olamide. "Quantitative characterisation of channel sinuosity, determination of catchment and sedimentary basin controls on channel sinuosity and interpretation of channel planform in fluvial systems with GIS and remote sensing techniques." Thesis, University of Aberdeen, 2015. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=226793.
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This work have quantitatively determine the catchment variables controlling the sinuosity transition of non-valley constrained DFS channels in Alaska, Himalaya and the Andes. Results from the characterisation of channel sinuosity were used through regression analyses to determine the catchment and channel bed parameters controlling reach sinuosity trend and transition of fluvial channel planforms in order to infer a control on the heterogeneity of DFS in the rock record. The catchment approach used was necessary because the studied fluvial systems are associated with DFS (which are regarded as larger forms of alluvial fans) and catchment based approach have been used to investigate controls on alluvial fan morphology. In addition, catchment based investigations are rare in the analyses of the discriminant functions that are considered as controlling factors on channel sinuosity and planform employed previously in the tributary systems. Two distinct channel types were found through the characterisation of 553 reaches of fluvial channels in 3 different modern continental sedimentary basins; channels with no transition in sinuosity/planform (group 1), and channels with transition in sinuosity/planform (group 2) Among the channel bed and catchment quantitative variables investigated in this work, catchment area is the only parameter that shows a general relationship with the channel distance from the apex to the transition point in channel sinuosity through the overall regression results. The result shows that the bigger the catchment area the longer the transition point which is related to a higher water and sediment discharge. Thus, the point at which the channel sinuosity transition will occur can be predicted from the catchment area through the regression equation [y=0.0017x + 28] of the overall linear regression line, where x is the catchment area and y is the channel distance from the apex to the point of transition in channel sinuosity. As the studied channels are associated with DFS, this relation also reflects the prediction of the transition point in the DFS fluvial styles in the rock record. Overall regression analysis results show statistically poor results for the relationship between catchment elevation, catchment slope, channel bed elevation, channel bed slope and either the channel sinuosity or the sinuosity transition. However, in all the three study areas, the majority of the datasets show a trend with the catchment area/sinuosity transition relationship. Additionally, the study area with mainly the biggest catchments (longer channel sinuosity transition) is associated with the highest catchment slope, lowest channel bed elevation and more anabranching channels. Also, the study area with mainly the smallest catchments (shorter channel sinuosity transition) is associated with lower catchment slope, higher channel bed elevation and fewer anabranching channels. This suggests that the higher water and sediment discharge may be related to the steeper slopes and the anabranching channels may reflect the lower channel bed elevation. However, deviations obeserved in the overall regression result in the three study areas are attributed to the differences in the climatic, geologic and tectonic factors in the 3 settings. Although, the differences in these study areas have been shown, nevertheless the interpretations cannot be substantiated in this work with the available data. Thus, there is need for further research to prove any conclusive relationship between these factors and hence remains an issue of debate. In conclusion, this work shows that catchment area is an important controlling parameter on the transition in channel sinuosity of non-valley constrained DFS channels and consequently reflects a a control on the transition in spatial variations of the associated DFS in the rock record.
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Burnham, Brian. "Quantitative characterisation and analysis of siliciclastic fluvial depositional systems using 3D digital outcrop models." Thesis, University of Manchester, 2016. https://www.research.manchester.ac.uk/portal/en/theses/quantitative-characterisation-and-analysis-of-siliciclastic-fluvial-depositional-systems-using-3d-digital-outcrop-models(fdca666e-ac58-4da3-a546-3d2259533a98).html.
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Outcrop analogue studies of fluvial sedimentary systems are often undertaken to identify spatial and temporal characteristics (e.g. stacking patterns, lateral continuity, lithofacies proportions). However, the lateral extent typically exceeds that of the exposure, and/or the true width and thickness are not apparent. Accurate characterisation of fluvial sand bodies is integral for accurate identification and subsequent modelling of aquifer and hydrocarbon reservoir architecture. The studies presented in this thesis utilise techniques that integrate lidar, highresolution photography and differential geospatial measurements, to create accurate three-dimensional (3D) digital outcrop models (DOMs) of continuous 3D and laterally extensive 2D outcrop exposures. The sedimentary architecture of outcrops in the medial portion of a large Distributive Fluvial System (DFS) (Huesca fluvial fan) in the Ebro Basin, north-east Spain, and in the fluvio-deltaic succession of the Breathitt Group in the eastern Appalachian Basin, USA, are evaluated using traditional sedimentological and digital outcrop analytical techniques. The major sand bodies in the study areas are quantitatively analysed to accurately characterise spatial and temporal changes in sand body architecture, from two different outcrop exposure types and scales. Several stochastic reservoir simulations were created to approximate fluvial sand body lithological component and connectivity within the medial portion of the Huesca DFS. Results demonstrate a workflow and current methodology adaptation of digital outcrop techniques required for each study to approximate true geobody widths, thickness and characterise architectural patterns (internal and external) of major fluvial sand bodies interpreted as products of DFSs in the Huesca fluvial fan, and both palaeovalleys and progradational DFSs in the Pikeville and Hyden Formations in the Breathitt Group. The results suggest key geostatistical metrics, which are translatable across any fluvial system that can be used to analyse 3D digital outcrop data, and identify spatial attributes of sand bodies to identify their genetic origin and lithological component within fluvial reservoir systems, and the rock record. 3D quantitative analysis of major sand bodies have allowed more accurate width vs. thickness relationships within the La Serreta area, showing a vertical increase in width and channel-fill facies, and demonstrates a 22% increase of in-channel facies from previous interpretations. Additionally, identification of deposits that are products of a nodal avulsion event have been characterised and are interpreted to be the cause for the increase in width and channel-fill facies. Furthermore, analysis of the Pikeville and Hyden Fms contain sand bodies of stacked distributaries and palaeovalleys, as previously interpreted, and demonstrates that a 3D spatial approach to determine basin-wide architectural trends is integral to identifying the genetic origin, and preservation potential of sand bodies of both palaeovalleys and distributive fluvial systems. The resultant geostatistics assimilated in the thesis demonstrates the efficacy of integrated lidar studies of outcrop analogues, and provide empirical relationships which can be applied to subsurface analogues for reservoir model development and the distribution of both DFS and palaeovalley depositional systems in the rock record.
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Sinawi, Ghida. "Aggregation of suspended sediment in fluvial systems : a case study of the River Exe." Thesis, University of Exeter, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.307289.
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Osei, Nana Akwasi. "Large wood in fluvial systems : quantity, structure and landforms, sediment retention, and riparian seed bank development." Thesis, Queen Mary, University of London, 2014. http://qmro.qmul.ac.uk/xmlui/handle/123456789/8813.
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This thesis investigates the characteristics and impacts of large wood accumulations within river reaches of different size and style. Four reaches were studied: (i) a wide, braided, headwater reach, characterised by dead wood (Tagliamento River, Italy); (ii) a lower gradient, wide, braided reach, characterised by resprouting wood (Tagliamento River, Italy); (iii) a low gradient, single thread reach with a natural supply of dead wood (Highland Water, UK), and (iv) a low gradient, single thread reach that has been restored by felling trees into the river (River Bure, UK). In each reach, quantities of wood, types of accumulation and their association with sediment retention, landform and propagule bank development were investigated, generating four main findings: 1. There were marked differences in the size and character of large wood accumulations among the four reaches. 2. Retention of fine sediment and organic matter by wood was observed on all four reaches, giving rise to notable spatial heterogeneity in surface sediments. 3. Sediment retention resulted in the development of different landforms among the four reaches. In the two multi-thread reaches, accretion of finer sediment around large wood led to island development. In the naturally-functioning single-thread reach, wood jams spanned the river channel, accumulating sediment and organic matter to produce unvegetated wood jams, and inducing other landforms, notably pools and bars. Such geomorphic heterogeneity was anticipated in the restored reach, but to date this has not significantly occurred. 4. Spatio-temporal variations were observed in propagule abundance and species richness within different wood-related mesohabitats. Higher abundance and species richness were associated with finer, more organic sediments retained within wood accumulations and related mesohabitats. In the restored reach such associations were not statistically significant, further indicating that responses to wood emplacement take longer than the 4 years since restoration. iv Overall, this research has strengthened the evidence concerning the differing nature of wood accumulations in rivers of different size and style, and it has demonstrated the importance of large wood for retaining organic matter and plant propagules, resources essential for riparian vegetation succession and for the success of river restoration efforts.
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Nash, David J. "The development and environmental significance of the dry valley systems (mekgacha) in the Kalahari, central southern Africa." Thesis, University of Sheffield, 1992. http://etheses.whiterose.ac.uk/5976/.
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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.
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Pawson, Richard Raymond. "Assessing the role of particulates in the fluvial organic carbon flux from eroding peatland systems." Thesis, University of Manchester, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.508922.
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Cannan, Caroline Elizabeth. "Scales of macroinvertebrate-habitat relationships in fluvial systems, a case study of the River Frome." Thesis, University of Southampton, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.285887.
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Davis, J. M. "The geology of ancient fluvial and lacustrine systems in Arabia Terra and Melas Chasma, Mars." Thesis, University College London (University of London), 2017. http://discovery.ucl.ac.uk/10027590/.
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Fluvial and lacustrine processes were abundant on early Mars. However, key questions remain about the extent of these processes and the climate in which they formed. This thesis examines two regions of Mars, Arabia Terra and Melas Chasma, using high-resolution, remote sensing datasets, with a focus on (1) the influence of fluvial and lacustrine processes on the landscape and (2) the implications for the early martian climate and environment. I first investigate Arabia Terra, a Noachian region of the southern highlands, and have produced a regional map of fluvial landforms. Fluvial channels and paleolakes preserved as inverted relief are pervasive throughout Arabia Terra and may represent the depositional component of a regional, south to north fluvial transport system. In addition, I have produced a geological map of one of these inverted systems, which reveals a complex stratigraphy and demonstrates that fluvio-lacustrine processes are concentrated on the oldest terrains. These fluvial systems are strongly consistent with widespread precipitation and runoff across early Mars. The second region of investigation is the Hesperian south-western Melas Chasma basin, part of the Valles Marineris canyon system. Here I have produced a map of fluvial landforms, which indicates that fluvial processes were episodic and extended over a protracted period of time. I also examine the stratigraphic sequence within the central palaeolake in the basin, where evidence for episodic aqueous processes is also identifed. The south-western Melas Chasma basin provides strong evidence that fluvio-lacustrine processes on Mars continued for much of the early and middle history of Mars.
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Santos, Mauricio Guerreiro Martinho dos. "Evolução dos sistemas fluviais através do tempo geológico: fácies sedimentares, arquitetura deposicional e estruturas de deformação sinsedimentar em exemplos do Torridonian, Bacia do Camaquã e Old Red Sandstone." Universidade de São Paulo, 2014. http://www.teses.usp.br/teses/disponiveis/44/44141/tde-10102014-085051/.
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Uma série de pesquisas realizadas em depósitos de sistemas fluviais, desenvolvidos anterior e concomitantemente à colonização dos continentes por vegetação, são aqui apresentadas com o intuito de investigar as principais características deposicionais destes sistemas, particularmente suas assembléias de fácies e elementos arquitetônicos preservados. Esta pesquisa busca, desta maneira, propor modelos deposicionais para sucessões fluviais pré-vegetação e contribuir para o avanço do conhecimento sobre as mudanças seculares em padrões de sedimentação, principalmente em relação à evolução dos rios através do tempo geológico. Estudos sedimentológicos foram realizados em depósitos fluviais da Formação Applecross do Grupo Torridon (Toniano, Escócia), Formação Guarda Velha do Grupo Guaritas (Cambriano, Brasil) e no Old Red Sandstone do Midland Valley (Siluriano-Carbonífero, Escócia). Foram empregadas análises de associações de fácies e arquitetura deposicional por meio de estudos de alto detalhe em afloramentos, combinadas a análises de paleocorrentes, de proveniência, e de estruturas de deformação sinsedimentar. Depósitos de canais fluviais meandrantes pré-vegetação com espessos depósitos de planícies de inundação ricos em sedimentos de granulação fina são pela primeira vez descritos em detalhe nos estudos aqui apresentados sobre depósitos da Formação Applecross. Diversas estruturas de deformação sinsedimentar encontradas na unidade acima referida são analisadas, revelando que seus estilos podem ser relacionados a diferentes regiões de uma planície fluvial. Nos depósitos da Formação Guarda Velha, é registrada a inter-relação entre dois sistemas fluviais coevos, cuja arquitetura deposicional contrastante resultou da diferente localização destes sistemas em relação à estrutura da bacia, assim como de diferentes áreas de captação. São relatados os efeitos de distintos controles deposicionais, como ambiente tectônico e regimes hidráulicos, sobre a arquitetura deposicional preservada em sistemas fluviais pré-vegetação. Esses dados demonstram que o estilo entrelaçado-em-lençol, apontado como o estilo pré-vegetação predominante, engloba na verdade uma variedade de diferentes estilos fluviais. Estudos em depósitos do Siluriano ao Carbonífero do Old Red Sandstone revelam o crescente impacto da vegetação sobre depósitos fluviais, particularmente o aumento exponencial de formação de paleosolos, além de mostrar semelhanças entre alguns destes sistemas com os sistemas pré-silurianos. A integração desses estudos revela que sistemas fluviais pré-vegetação são relativamente mais complexos do que previsto pelos modelos atualmente disponíveis. Importantemente, sugere que a escassez de sedimentos de granulção fina, preservados em depósitos fluviais pré-silurianos, está mais relacionada à baixa competência destes sistemas em preservar tais sedimentos do que à sua suposta ausência em ambientes pré-vegetação. Foi também desenvolvida uma metodologia específica para o uso de estruturas de deformação em sedimentos inconsolidados como ferramentas na reconstrução de paleoambientes, através das relações entre diferentes estilos deformacionais e ambientes deposicionais, possibilitando a indicação de regimes hidráulicos em depósitos fluviais e a informação indireta de taxas de atividades tectônicas em bacias. A integração de dados de sedimentologia com estudos específicos de deformação sinsedimentar é uma ferramenta útil na reconstrução paleoambiental de sistemas fluviais.A series of studies were undertaken on fluvial systems deposits which developed prior to land-plant colonization, in order to investigate the main depositional characteristics of those systems, particularly their main facies assemblages and preserved depositional architecture. Main objectives are the proposal of depositional models for pre-vegetation fluvial systems, and the understanding of main secular changes in sedimentation processes and its influence on the evolution of rivers through geological times. Sedimentologic studies were undertaken in fluvial deposits from the Applecoss Formation of the Torridon Group (Tonian, NW Scotland), the Guarda Velha Formation (Cambrian, southern Brazil), and the Old Red Sandstone in the Midland Valley (Silurian-Carboniferous, NE Scotland). Highly-detailed sedimentary facies and depositional architecture analyses in outcrop scale were integrated with palaeocurrent and provenance studies, and soft-sediment deformation analysis. Pre-vegetation meandering channel deposits with relatively thick, fine-grained floodplain deposits from the Applecross Formation and here described for the first time. Analyses on sinsedimentary deformation structures preserved in the Applecross Formation reveal different styles which can be related to different parts of the fluvial plain. Studies on the Guarda Velha Formation revealed the inter-relationship between two coeval fluvial systems with markedly contrasting preserved depositional architecture, which developed as a result of the different location of the systems in relation to basin structure and different caption areas. The effects of different depositional controls on preserved pre-vegetation fluvial system architecture, such as tectonic environment and hydraulic regime, are recorded and interpreted. The present data demonstrate that the sheet-braided style, which is regarded as the prevailing fluvial style before the Silurian, in fact encompasses a varied number of different pre-vegetation fluvial styles. Studies on the Silurian to Early Carboniferous Old Red Sandstones in the Midland Valley of Scotland reveal the progressive impact of land plants on fluvial sedimentation, particularly the exponential increasing rates of soil production. Integration of the here presented data reveal that pre-vegetation fluvial styles. Studies on the Silurian to Early Carboniferous Old Red Sandstone in the Midland Valley of Scotland reveal the progressive impact of land plants on fluvial sedimentation, particularly the exponential increasing rates of soil production. Integration of the here presented data reveal that pre-vegetation fluvial systems are relatively more complex than previously described in the literature. Importantly, it suggests that the paucity of fine-grained sediments in pre-Silurian fluvial deposits is most likely related to various preservation issues than to the lack of such sediments. A particular methodology for the use of soft-sediment deformation structures as palaeoenvironmental tool was developed, allowing the interpretation of hydraulic regimes in fluvial deposits, indication of the basin\'s tectonic activity, and the relationship between different deformation styles and distinct depositional environments. The combined analyses of soft-sediment deformation structures and sedimentologic data is a powerful tool with which fluvial systems palaeoenvironmental can be reconstructed.
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Clarke, Paul Richard. "Facies architecture, depositional systems and correlation of Triassic fluvial-lacustrine-marginal marine deposits from Northwestern Europe." Thesis, University of Birmingham, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.246698.
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Hall, Philip Edward. "The evolution of Permo-Triassic fluvial and alluvial systems in the central Iberian basin, central Spain." Thesis, Durham University, 2005. http://etheses.dur.ac.uk/1796/.
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Almasrahy, Mohammed Ali Jbreel. "Fluvial and aeolian interactions in modern and ancient dryland continental sedimentary systems : implications for reservoir heterogeneity." Thesis, University of Leeds, 2015. http://etheses.whiterose.ac.uk/12689/.
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Quantitative stratigraphic prediction of the three-dimensional form of sedimentary architectures and associated heterogeneities arising from fluvial and aeolian interactions and preserved as accumulated stratigraphic successions is notoriously difficult, meaning that prediction of 3D stratigraphic architectures in subsurface fluvial and aeolian reservoirs is challenging. This study comprises four discrete but related research components: (1)analysis of aeolian dune-field geomorphology through a remotely sensed analysis of four parts of the Al Rub’ Al-Khali Desert, Saudi Arabia; (2) analysis of types of aeolian-fluvial system interaction in modern dune-field margins through study of the morphological expression and areal distribution of 130 examples of fluvial-aeolian interaction mapped by high-resolution satellite imagery from 60 deserts around the world; (3) analysis of the preserved stratigraphic expression of an ancient mixed aeolian and fluvial succession via analysis of the upper part of the Wilmslow Sandstone and the lower part of the overlying Helsby Sandstone formations, Sherwood Sandstone Group, UK; (4) development of a series of predictive, semiquantitative facies models with which to account for the geological complexity and origin of mixed aeolian-fluvial successions. Principal finding are as follows: (1) observations from the Rub’ Al-Khali Desert have enabled the spatial rate of change of morphology of aeolian subenvironments to be characterized and described through a series of empirical relationships; (2) aeolian-fluvial interaction case-study examples have been classified to propose a framework of ten distinct types of system interactions;(3) outcrop analysis of an ancient preserved succession reveals mechanisms for the accumulation and preservation of aeolian and fluvial successions, and demonstrates the role of water table on the development and preservation of a water-table influenced aeolian system; (4) results from this study have enabled the development of facies models that serve as the basis for gaining an improved understanding of controls governing the detailed sedimentary architecture of preserved aeolian-fluvial successions.
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White, Alicia. "The Influence of Physical and Anthropogenic Factors on a Channel’s Geomorphic Diversity." Thesis, School of Geosciences, 2009. http://hdl.handle.net/2123/5776.
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The geomorphic diversity (or the natural variability within and between geomorphic structures) of fluvial systems provides an indication of river health and biological activity as well as their resilience to change. Despite this, few studies have investigated the controls on geomorphic diversity and, as a result, our understanding of this fundamental aspect of rivers is incomplete. Similarly, investigations into the controlling factors on channel morphology tend to be limited in scope. For example, the influence of physical and anthropogenic external factors on the morphology of fluvial systems has typically been examined through the study of the effects of a single factor (e.g., woody debris) on either the cross-sectional form, the shape of the long-profile, the bed structure or the channel pattern of a river system. As rivers have been shown to adjust their channel morphologies to external controls (Knighton 2000) over all four of these degrees of freedom, isolating individual degrees of freedom may miss out on the complex interactions that occur between them. The aim of this study, therefore, is to examine the multi-scale and multifactor influences of physical and anthropogenic external factors (particularly confinement, riparian vegetation, woody debris, obstructions and anthropogenic impoundment) on the geomorphic structure and diversity of river systems at a range of scales, using the Turon River in Central West New South Wales as a case study. In this study, river channels were examined at four scales (i.e., cross-section, long-profile, bedform and bar unit) to assess the influence of five external factors (confinement, riparian vegetation, woody debris, obstructions (i.e., islands and in-channel bars) and anthropogenic impoundment (i.e., a causeway)) on the geomorphic diversity of the Turon River. To accomplish this, a total of 231 cross-sections were surveyed over a 600 m reach. These data were then used to calculate the size and variability of cross-sections, long-profiles, bedforms and bar units within the study reach. Morphology and diversity at each scale (and for each factor) were tested for statistical differences using non-parametric uni-variate approaches. The results presented in this study suggest that the presence of obstructions is the most influential external factor on channel size in the Turon River, affecting the size and shape of cross-sections, long-profiles and, to a lesser extent, bedforms and bar-units. That is, obstructed channels were found to be significantly different to channels devoid of obstructions insofar as they were smaller, shallower, contained steeper channel gradients had more vertical variation in their long-profiles, had longer pool-riffle sequence spacing and were of a different channel form to channel reaches devoid of obstructions. Obstructions, in association with the presence and type of woody debris, were also observed to be the most influential factors on the diversity of river channels. For example, the presence of either obstructions or woody debris increased the variability of crosssectional and bedform parameters, while the type of woody debris present influenced the variability of the long-profile’s vertical and angular variations (i.e., the vertical and angular variations in long-profiles containing in-channel woody debris were less variable than those with on-bank woody debris). Importantly, cross-sections are impacted upon more than long profiles, with their size and variability affected by both large-scale external factors (e.g., confinement and riparian vegetation) and small-scale influences (e.g., obstructions and impoundments). For example, cross-sections within confined reaches were found to be larger but less diverse than crosssections in unconfined channels, while the reverse is true for obstructed cross-sections (i.e., obstructed cross-sections were smaller and more diverse than unobstructed channels). Conversely, pool-riffle sequences were the least affected river components, only being influenced by obstructions and, to a lesser extent, woody debris. That is, bar-units within obstructed channels were smaller, longer and more asymmetric than bar-units within channels devoid of obstructions. The results presented in this study also indicate that the variability of channel characteristics was affected more by the influence of external factors than channel dimensions. Additionally, the findings of this study indicate a reversal in the influence external factors have on the size and shape of a channel and its diversity. That is, smaller channels were found to be more diverse than larger channels. This is the first study to examine the influence of multiple factors on multiple scales within a river reach. The results of this investigation illustrate that river systems have complex responses to a combination of different physical and anthropogenic external factors that are evident at multiple scales (from cross-sections through to bar units). Additionally, it has shown that interactions between the external factors in a reach can result in a highly geomorphically diverse environment.
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Luz, Rodolfo Alves da. "Mudanças geomorfológicas na planície fluvial do Rio Pinheiros, São Paulo (SP), ao longo do processo de urbanização." Universidade de São Paulo, 2014. http://www.teses.usp.br/teses/disponiveis/8/8135/tde-29062015-152030/.
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O sistema fluvial meândrico do Rio Pinheiros em São Paulo (SP) tem passado por muitas mudanças geomorfológicas devido a intervenções antrópicas decorrentes da urbanização. A hipótese motivadora é a de que estas mudanças apresentam magnitudes maiores ou equivalentes àquelas registradas em condições naturais ou não urbanizadas. A pesquisa foi realizada por meio de técnicas oriundas da geomorfologia antrópica e histórica, do mapeamento geomorfológico e da análise de geoindicadores de mudanças nas formas da Terra, nos materiais superficiais e nos processos. Por meio da elaboração de três cartas geomorfológicas na escala de 1:25.000 representativas de distintos estágios de perturbação antrópica (pré-perturbação, perturbação ativa e pós-perturbação), foi possível identificar e dimensionar as mudanças históricas no sistema hidromorfológico desde 1930. Os resultados revelaram a elevada magnitude e alta eficiência das intervenções humanas diretas e indiretas nas morfologias e processos hidromorfológicos. Mudanças esperadas para ocorrer em condições naturais ou não urbanas em intervalos de 1 em 10³ a 1 em 104 anos podem se tornar eventos mais frequentes e instantâneos devido à urbanização (1 em 100 a 1 em 10² anos), fazendo as fontes históricas bastante adequadas para a sua identificação. Em apenas 21 anos, o canal meândrico pré-urbano foi substituído por um canal artificial retilíneo, seu comprimento foi reduzido em 44,9% e sua largura foi aumentada em 184,9%. O canal anterior transportava sedimentos finos e matéria orgânica num fluxo dágua constante para jusante. O canal atual tem uma vazão baixa e controlada artificialmente por estruturas de engenharia, que podem reverter o fluxo dágua para montante, fazendo com que o antigo sistema fluvial fosse transformado em um sistema próximo ao lacustre. A maioria dos sedimentos, matéria orgânica e poluentes é depositada no leito do canal, gerando problemas ambientais e de assoreamento. Nos últimos 80 anos, a antiga planície de inundação foi suprimida e novos níveis de terraços foram criados pela atividade humana, especialmente por aterros, cujo volume foi estimado em 16,28x106 m3. As inundações por extravasamento do canal foram reduzidas por causa das estruturas de controle de cheias, e ficam restritas às suas margens imediatas. Entretanto, a capacidade de atenuação das inundações da planície de inundação e baixos terraços foi perdida, e a frequência e magnitude das inundações foram potencializadas por causa da rede de drenagem urbana deficiente, da obstrução por aterros e pela construção de avenidas de fundo de vale nos rios afluentes. Compreender mudanças de tal magnitude auxilia na gestão dos rios e planícies urbanas, nos levantamentos geotécnicos e na identificação das possibilidades de recuperação ambiental, onde as funções ecológicas, hidrológicas e sociais dos sistemas fluviais devem ser restauradas.The urbanised meandering fluvial system of River Pinheiros in Sao Paulo, Brazil, has undergone many geomorphological changes due to human interventions during the urban development. The central hypothesis is that geomorphological changes related to urbanisation over a fluvial plain in tropical humid environment present magnitudes higher than, or similar to, natural or non-urban systems. These changes can be explained by using such techniques as anthropic and historical geomorphology, geomorphological mapping, and geoindicators of change in landforms, materials and processes. Three 1:25,000 geomorphological maps of representative stages of intervention (pre-disturbance, active disturbance and post-disturbance) helped to establish, measure and compare historical changes in the hydromorphological system since 1930. The results revealed the great magnitude and high efficiency of direct and indirect human interventions on fluvial landforms and hydromorphological processes. Changes that might be expected to occur at intervals of 1 in 10³ to 1 in 104 years in natural conditions can become much more frequent events (1 in 100 to 1 in 10² years) due to urbanisation, making the historical sources quite suitable for the identification of these modifications. In just 21 years the pre-urban meandering channel was replaced by a straight and artificial canal, with the length being reduced by 44.9%, the width being increased by 184.9%. The previous fluvial channel carried fine sediments and organic matter in a constant downstream water flow. The current canal has the water flow artificially controlled by engineering structures which can be reversed upstream and, nowadays, behaves as a series of lakes with negligible flow. Most of sediments, organic matter and pollutants are deposited in the canal bed, generating siltation and environmental problems. During the last 80 years the previous floodplain level was eliminated and new terrace levels were created by human activity, particularly by landfills whose volume was estimated to be 16.28x106 m3. Floods by channel overflow were reduced by the engineering structures and are restricted to the nearest banks. However, the flood attenuation capacity of the floodplain and lower terraces was lost and the flood frequency and magnitude was enhanced due to deficient urban drainage, landfill blockage and where the tributaries were recovered by roads. Understanding changes of this magnitude can assist in river and flood management in urban areas, in geotechnical surveys and in the landscape reclamation.
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Heaton, V. "Decomposition of Human Remains Recovered from the River Clyde, Scotland: A comparative Study of UK Fluvial Systems." Thesis, University of Central Lancashire, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.527060.
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Allen, Phillip Paul. "Geomorphic response of upslope and fluvial systems to Holocene environmental change : Brandon Mountain Massif, Dingle Peninsula, Southwest Ireland." Thesis, Coventry University, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.419760.
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Perks, Matthew Thomas. "Spatial and temporal dynamics of fine fluvial sediment transfer : implications for monitoring and management of upland river systems." Thesis, Durham University, 2013. http://etheses.dur.ac.uk/7307/.
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Although the impacts of changing land use on the magnitude and timing of erosion in lowland catchments are well documented, much less is known about the transfer dynamics of fine sediment through the upland hydrological networks. Using a novel distributed monitoring approach, this thesis examines the magnitude, timing and physical characteristics of fluvial fine sediment in two adjacent upland rivers in North Yorkshire (UK). Annual suspended sediment yield (SSY) estimates range from 33.92 t km-2 in the 131 km2 Upper Derwent catchment to 57.91 t km-2 in the 96 km2 River Esk catchment. Infrequent events were found to be of greatest importance, transferring up to 38% of the annual load in under two days. Simple annual and seasonal rating curves were constructed and are effective in predicting SSC with relative errors of less than 15%. Analysis of within-storm fine sediment dynamics indicated the dominance of sources proximal to the channel in the Esk catchment, whereas sediment sources in the Upper Derwent were more variable. Distributed time-integrated fine sediment sampling identified high SSYs in the headwaters of the Upper Derwent whereas in the headwaters of the Esk the minimum SSY was found with tributaries draining the central valley having maximum SSYs. Analysis of the absolute particle size observed significant downstream fining in both catchments and strong positive relationships between flow and particle size of the transported sediment. The data collected are also applied to four real-world scenarios to demonstrate the effectiveness of this approach. This research has enhanced our understanding of fine sediment delivery to upland channels through the assessment of the fine sediment dynamics at a range of temporal and spatial scales rarely studied in these environments.
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Colombera, Luca. "A database for the digitization of the sedimentary architecture of fluvial systems : uses in pure and applied research." Thesis, University of Leeds, 2013. http://etheses.whiterose.ac.uk/5737/.
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A relational database has been devised as a tool for the digitization of features relating to the sedimentary and geomorphic architecture of modern rivers and ancient fluvial successions, as derived from either original field studies or published examples. The system has been designed in a way that permits the inclusion of hard and soft data – comprising geometries and spatial and hierarchical relationships – referring to classified genetic units belonging to 3 different hierarchical levels, and assigned to stratigraphic volumes that are categorized in terms of deposystem boundary conditions and descriptive parameters. Several applications of the quantitative information generated through database interrogation have been explored, with the scope to demonstrate how a database methodology for the storage of sedimentary architecture data can be of use for both pure and applied sedimentary research. Firstly, an account is given of how the system can been employed for the creation of quantitative fluvial facies models, which summarize information on architectural styles associated with classes of depositional systems. The value of the approach is shown by contrasting results with traditional qualitative models. Secondly, database output on large-scale fluvial architecture has been used in the context of a comparative study aiming to investigate the role of basin-wide aggradation rates as predictors of fluvial architectural styles. The results contrast with what might be expected by commonly considered stratigraphic models; the main implication is the necessity to reconsider continental sequence stratigraphy models or their domain of applicability. This application further provides an example of how the methodology could be generalized to the study of the sensitivity of architecture to its controls. Thirdly, database output has been used to conduct a re-evaluation of previously-proposed approaches to the guidance of well-to-well correlations of subsurface fluvial channel bodies, applied in earlier studies. Making use of the same analogue information, a new probabilistic approach has been proposed as a way to inform or rank correlation panels of channel bodies across equally-spaced wells. Finally, the value of the system as an instrument for constraining object- and pixel-based stochastic structure-imitating models of fluvial sedimentary architecture is collectively demonstrated through a range of example applications employing database output.
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Mathias, Tiago Novaes. "Análise de sistemas integrados de transporte rodo-fluvial-marítimo sob a influência de regimes sazonais." Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/3/3148/tde-05122016-100739/.
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Este trabalho está voltado à avaliação dos problemas do transporte intermodal sob efeito de restrições sazonais que, usualmente, não são consideradas na fase de planejamento e dimensionamento da frota. E, considerando a sobreposição de dois fatores sazonais restritivos ao longo da cadeia de transportes - a variação na produção de grãos ao longo do ano e a sazonalidade das cotas de nível d\'água nas hidrovias -, um modelo de simulação de eventos discretos mostra as impedâncias sofridas no sistema pela junção de fatores restritivos bem fortes. É possível avaliar o impacto dessas restrições não só no nível de utilização dos silos intermediários e silagem do porto, mas também no número de veículos necessários para fazer o transporte de commodities na região Centro-Oeste do Brasil. Em um sistema de transporte composto pelos modais rodoviário, hidroviário e marítimo, no qual o modelo de simulação abrange desde a produção nas fazendas, passando pelo transporte de caminhão até os armazéns intermediários, posteriormente com o transporte fluvial com destino ao porto para exportação. O presente estudo traz uma série de comparações entre cenários para avaliação dos gargalos existentes neste sistema de transporte intermodal, especialmente avaliando cenários com e sem as restrições sazonais, assim como análises de sensibilidade de performance de equipamentos de carregamento e descarregamento, nos quais a frota e os estoques necessários são substancialmente diferentes se a sazonalidade não for considerada.This work focuses on the evaluation of the intermodal transport problems under the influence of seasonal constraints that are not usually considered on the phase of planning and sizing the fleet. Considering the superposition of two different seasonal factors along the transportation chain - first one the variation on grain production and the second one the level of water in the waterways throughout the year -, a discrete event simulation model was built to show the real effects of those constraints in the grain supply chain. So, it is possible to evaluate the impact of those constraints not only on the usage level of storages in this system, but also the number of vehicles required to transport this commodities from the Midwest of Brazil to the port. In a complex multimodal transportation system, the simulation model in this work includes roadways, waterways and seaways to transport all the cargo from farms to the final costumer. This study is composed by a number of scenarios to evaluate the bottlenecks in this intermodal transportation system, specially analyzing scenarios with and without seasonal constraints, as well as analysis of sensitivity of performance of equipment of loading and unloading, in which the fleet and the required stocks are substantially different if seasonality is not considered. In other words, it is possible to evaluate the risks involved when managers are making decisions if they do not take in consideration any of those seasonal constraints.
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Archer, Stuart G. "The sequence stratigraphy and correlation of dryland fluvial systems : a geomorphic perspective from Basin and Range Province, SW USA." Thesis, University of Aberdeen, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.440093.
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This study uses geomorphic observations from the Basin and Range Province, SW USA, to ground truth dryland sequence stratigraphic concepts in an intra-continental rift setting. Three geomorphic experiments were designed to test the sequence stratigraphic response to changes in the allogenic variables of 1) climate, 2) tectonics and 3) base level. 1) A regional synthesis of the alluvial response to Pleistocene-Holocene acidification has been compiled from case study areas 1000 km apart. This analysis reveals three different alluvial responses, depending on the subtle interplay between sediment supply and discharge. The search for a regionally correlatable alluvial response to climate change may therefore be futile. 2) Morphometric analysis has identified a spectrum of tectonically generated landforms. These include both tectonically immature and mature elements. These observations indicate that ancient continental rifts will also have been prone to the coeval existence of highly contrasting maturity domains. Additionally, in contrast to recently published literature, variable subsidence patterns do not provide the dominant control on alluvial fan size. A holistic re-evaluation of the factors governing fan size indicates that the key variables are: sediment supply (primarily catchment area, but also attitude and gradient) and vertical and horizontal accommodation space (subsidence rates and basin width respectively). 3) Structural sills provide a form of tectonic base level that can partition rift basins. Their potential influence on drainage organisation, and the extent of sequence boundaries has been previously under-appreciated.
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Rocchio, Andrea Michelle. "A Comparison of Rural and Urban Fluvial Systems as a Function of Land Cover Changes in Summit County, Ohio." University of Akron / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=akron1491401461044589.
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Roebuck, J. Alan Jr. "Environmental Dynamics of Dissolved Organic Matter and Dissolved Black Carbon in Fluvial Systems: Effects of Biogeochemistry and Land Use." FIU Digital Commons, 2018. https://digitalcommons.fiu.edu/etd/3755.
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Black carbon (BC) is an organic residue formed primarily from biomass burning (e.g., wildfires) and fossil fuel combustion. Until recently, it was understood that BC was highly recalcitrant and stabilized in soils over millennial scales. However, a fraction of the material can be solubilized and transported in fluvial systems as dissolved BC (DBC), which represents on average 10% of the global export of dissolved organic carbon (DOC) from rivers to coastal systems. The composition of DBC controls its reactivity, and it has been linked with a variety of in-stream processes that induce both carbon sequestration and evasion of CO₂ from aquatic systems, which suggest DBC may have a significant contribution within the global carbon cycle. The primary objectives for the thesis were to elucidate environmental factors that control the fate and transport of DBC in fluvial systems. Ultra-high resolution mass spectrometry was used to characterize DBC on a molecular scale whereas benzenepolycarboxylic acids were used to quantify and characterize BC in both dissolved and particulate phases (PBC). Sinks for polycondensed DBC were linked to a series of in-stream biogeochemical processes (e.g., photodegradation, metal interactions); whereas photooxidation of particulate charcoal led to production of DBC, suggesting photodissolution as a previously unrecognized source of DBC to fluvial systems. Coupling of DBC with PBC, however, was hydrologically constrained with sources varying over temporal scales and land use regimes. For DBC in particular, an enrichment of heteroatomic functionality was observed as a function of anthropogenic land use. Furthermore, land use coupled with stream order (a proxy for in-stream processing as defined by the River Continuum Concept) could explain significant spatial variability in organic matter (e.g., DOC) composition within an anthropogenically impacted system. With an increase in wildfire frequency projected with on-going climate change trends, parallel projections for increases in BC production are also expected. Furthermore, conversion of natural landscapes for urban and agricultural practices is also expected to continue in the coming decades. Thus, it is imperative to reach a comprehensive understanding of processes regulating the transport of DBC in fluvial systems with efforts to constrain future BC budgets and climate change models.
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Praskievicz, Sarah. "A Hierarchical Modeling Approach to Simulating the Geomorphic Response of River Systems to Climate Change." Thesis, University of Oregon, 2014. http://hdl.handle.net/1794/18375.
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Anthropogenic climate change significantly affects water resources. River flows in mountainous regions are driven by snowmelt and are therefore highly sensitive to increases in temperature resulting from climate change. Climate-driven hydrological changes are potentially significant for the fluvial geomorphology of river systems. In unchanging climatic and tectonic conditions, a river's morphology will develop in equilibrium with inputs of water and sediment, but climate change represents a potential forcing on these variables that may push the system into disequilibrium and cause significant changes in river morphology. Geomorphic factors, such as channel geometry, planform, and sediment transport, are major determinants of the value of river systems, including their suitability for threatened and endangered species and for human uses of water.
This dissertation research uses a hierarchical modeling approach to investigate potential impacts of anthropogenic climate change on river morphology in the interior Pacific Northwest. The research will address the following theoretical and methodological objectives: 1) Develop downscaled climate change scenarios, based on regional climate-model output, including changes in daily minimum and maximum temperature and precipitation. 2) Estimate how climate change scenarios affect river discharge and suspended-sediment load, using a basin-scale hydrologic model. 3) Examine potential impacts of climate-driven hydrologic changes on stream power and shear stress, bedload sediment transport, and river morphology, including channel geometry and planform.
The downscaling approach, based on empirically-estimated local topographic lapse rates, produces high-resolution climate grids with positive forecast skill. The hydrologic modeling results indicate that projected climate change in the study rivers will change the annual cycle of hydrology, with increased winter discharge, a decrease in the magnitude of the spring snowmelt peak, and decreased summer discharge. Geomorphic modeling results suggest that changes in reach-averaged bedload transport are highly sensitive to likely changes in the recurrence interval of the critical discharge needed to mobilize bed sediments. This dissertation research makes an original contribution to the climate-change impacts literature by linking Earth processes across a wide range of spatial scales to project changes in river systems that may be significant for management of these systems for societal and ecological benefits.
This dissertation includes unpublished co-authored material.
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Santana, Claudinei Lopes. "Geomorfologia da planície fluvial do rio Ribeira de Iguape entre Sete Barras e Eldorado (SP): subsídios ao planejamento físico-territorial de áreas inundáveis." Universidade de São Paulo, 2008. http://www.teses.usp.br/teses/disponiveis/8/8135/tde-07102009-152524/.
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Este estudo trata da caracterização hidromorfodinâmica de um setor paulista da planície fluvial meândrica do rio Ribeira de Iguape, abordando-se os três níveis da pesquisa geomorfológica de acordo com a concepção de HART (1986), a saber: (a) o nível descritivo da morfologia; (b) o nível descritivo dos materiais superficiais e solos; e (c) o nível analítico interpretativo dos processos, que, no caso, são hidrodinâmicos. Os resultados possibilitaram compreensão da hidromorfodinâmica das planícies fluviais meândricas em ambientes tropicais úmidos e, principalmente, da planície de inundação, podendo servir de subsídios no planejamento físico territorial regional, tendo em vista a importância da ocupação humana dentro desses setores.The objective of this research is the hydromorphodynamic characterization of the Paulista River Ribeira de Iguape sector, approaching three levels of the geomorphology research according HART (1986), to know: (a) the morphology descriptive level; (b) the superficial materials and ground descriptive level; and (c) the processes interpretation analytical level, or hydrodynamic processes. With these surveys and systematization was possible the partially understanding humid tropical environments hidromorphodynamics trends and, mainly, of the flooding plain, which can be used in the regional territorial physical planning, in view of the importance of the occupation human being on these sectors.
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Maia, R?bson Pinheiro. "Geomorfologia e neotect?nica no Vale do Apodi-Mossor? RN." Universidade Federal do Rio Grande do Norte, 2012. http://repositorio.ufrn.br:8080/jspui/handle/123456789/18363.
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Previous issue date: 2012-02-29Numerous studies have indicated that the Potiguar Basin is affected by Cenozoic tectonics. The reactivation of Cretaceous fault systems affect the post-rift units, witch include Neogene and overlying Quaternary sediments. In this context, the objectives of this thesis are the followings: (1) to characterize the effects of post-rift tectonics in the morphology of Apodi Mossor?-river valley located in the central portion of the Potiguar, (2) to characterize the drainage of the Apodi Mossor? river valley and investigate the behavior of their channels across active faults, and (3) to propose a geologic-geomorphological evolutionary model for the study area. This study used a geological and geomorphological mapping of the central part of the basin, with emphasis on the Quaternary record, luminescence dating of sediments, and geoelectric profiles of the area. The results reveal by maps of structural lineaments and drainage channels of the rivers form valleys that are affected by faults and folds. In Apodi-Mossor? valley, anomalies of channel morphology are associated with the deformation of the post-rift basin. These anomalies show the reactivation of major fault systems in the Potiguar Basin in Cenozoic. On a regional scale, can be seen through the vertical electric profiles that the Cenozoic tectonics is responsible for the elevation of a macro dome NE-SE-trending 70-km long and 50km wide and up to 270 above sea level. In this sector, the vertical electric profiles data show that the contact between the Cretaceous and Neogene rise more than 100m. This Is an important feature of inversion data obtained in this work showed that the deposits that cover the macro dome (Serra do Mel) have ages of 119 ka to 43 ka. In the river valley and surrounding areas Apodi-Mossor? ages vary between 319 ka and 2.7 ka. From these data it was possible to establish the correct geochronological posiconamento paleodep?sitos of distinguishing them from the fluvial deposits of the Neogene (Barreiras Formation)
Numerosos estudos t?m indicado que a Bacia Potiguar ? afetada pela tect?nica Cenoz?ica. A reativa??o de sistemas de falhas do Cret?ceo afetam as unidades p?s-rifte que incluem o Ne?geno e o Quatern?rio. Nesse contexto, os objectivos dessa tese s?o os seguintes: (1) Caracterizar os efeitos da tect?nica p?s-rifte na morfologia do Rio Apodi-Mossor? localizado na por??o central da Bacia Potiguar, (2) Caracterizar a drenagem do vale do Rio Apodi-Mossor? e investigar o comportamento de seus canais em falhas ativas, (3) Propor um modelo geol?gico-geomorfol?gico evolutivo para a ?rea de estudo. Esse estudo utilizou-se de um mapeamento geol?gico e geomorfol?gico da parte central da Bacia Potiguar, com ?nfase nos dep?sitos sedimentares quatern?rios, na data??o de sedimentos por luminesc?ncia ?ptica estimulada e sondagens geoel?tricas verticais. Os resultados revelam atrav?s de mapas de lineamentos estruturais e canais de drenagem que os rios formam vales que s?o afetados por falhas e deforma??es tect?nicas. No vale do Rio Apodi-Mossor?, anomalias da morfologia do canal est?o associadas ? deforma??o p?s-rifte da Bacia Potiguar. Essas anomalias evidenciam a influ?ncia da reativa??o cenoz?ica de sistemas de falhas da Bacia Potiguar na morfologia do canal. Em uma escala regional, pode ser visto atrav?s da geomorfologia e dos dados das sondagens geoel?tricas que a tect?nica cenoz?ica ? respons?vel pela forma??o de fei??es de invers?o resultantes do atual campo de tens?es na Bacia Potiguar. Essa fei??o caracteriza-se por um macro domo (Serra do Mel) orientado no sentido NE-SE com 70 km de comprimento e 50 km de largura e at? 270m acima do n?vel do mar. Nesse setor, os dados obtidos nesse trabalho evidenciaram que o contato entre o Cret?ceo e o Ne?geno eleva-se mais de 100m no centro da Bacia Potiguar. Os resultados geocronol?gicos obtidos nesse trabalho mostraram que os dep?sitos que cobrem o macro domo estrutural t?m idades de 119 ka a 43 ka. No vale do Rio Apodi-Mossor? e ?reas vizinhas, as idades variam entre 319 ka e 2,7 ka. A partir desses dados, foi poss?vel estabelecer o correto posiconamento geocronol?gico dos paleodep?sitos fluvias e distingu?-los dos dep?sitos do Ne?geno (Forma??o Barreiras)
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Richardson, Janet Cristine. "Antecedent fluvial systems on an uplifted continental margin : constraining Cretaceous to present-day drainage basin development in southern South Africa." Thesis, University of Leeds, 2016. http://etheses.whiterose.ac.uk/14429/.
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Reconstructing drainage evolution has important implications for constraining long-term source-to-sink configurations. Furthermore, the analysis of ancient landscapes can support research in geomorphological concepts such as steady state and landscape evolution modelling. Techniques such as cosmogenic dating and morphometric analysis have rarely been applied to investigate the long-term drainage evolution of systems draining southern South Africa. This study focusses on the large-scale antecedent Gouritz catchment, Western Cape. Integrating provenance, cosmogenic and geomorphological (planform / morphometric indices) evidence indicates the trunk rivers are Cretaceous or older in age (i.e. principal topography of Mesozoic age). The trunk rivers fed huge volumes of sediment offshore during large-scale Mesozoic exhumation of southern South Africa with remnant coeval deposits in onshore extensional basins. However, there is a mismatch of onshore exhumation and offshore deposition and material is now found on the Falkland Plateau; separating source-to-sink by 6000 km. During exhumation, large scale pediments formed that grade to individual base levels and should be taken as individual features, not ‘surfaces’ correlated across the continent. A second phase of pediment evolution occurred in the mid-Cenozoic, dissecting the pediments and eroding small catchments into the Cape Fold Belt. These smaller order streams are strongly affected by the tectonic grain of the fold belt, whereas the trunk rivers are not, which is shown by variation in morphometric indices. The lack of correlation between catchment properties and denudation rates indicate the system has decoupled and that allogenic factors are now dominant. Due to the low rates of denundation, weathering is currently the rate limiting factor. However, during the early evolution of the catchment, tectonic activity was more dominant than the present day. The ancient catchment is in geomorphic steady-state, and highlights the need for further research into long-term landscape evolution, and linkage to offshore depositional records.
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Souti, Maria Evangelia Verfasser], Helmut [Akademischer Betreuer] [Fischer, Helmut [Gutachter] Fischer, and Reiner [Gutachter] Gellermann. "Natural and artificial radionuclides as tracers in fluvial systems / Maria Evangelia Souti ; Gutachter: Helmut Fischer, Reiner Gellermann ; Betreuer: Helmut Fischer." Bremen : Staats- und Universitätsbibliothek Bremen, 2018. http://d-nb.info/1166849651/34.
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Marconato, Andre. "Planícies de inundação fluviais pré-vegetação: exemplos do Supergrupo Espinhaço (Mesoproterozoico, BA) e do Supergrupo Camaquã (Ediacarano-Cambriano, RS)." Universidade de São Paulo, 2014. http://www.teses.usp.br/teses/disponiveis/44/44141/tde-03122014-101307/.
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Planícies de inundação são áreas sujeitas a fluxo episódico de água, que devido a disponibilidade de água, nutrientes e substrato estável, foram largamente afetadas desde o surgimento e subsequente evolução de plantas vasculares terrestres. Neste contexto, a escassez de exemplos documentados de planícies de inundação formadas anteriormente ao período Siluriano contrasta com décadas de debate acerca dos efeitos da evolução de plantas terrestres em estilos de canais fluviais. Dada a importância de planícies de inundação como sítios de acumulação de partículas sedimentares, intemperismo de minerais silicáticos e desenvolvimento de perfis de solo, esta falta de dados sobre planícies de inundação antigas tem importante impacto na forma como entendemos sistemas transporte de sedimento, o registro climático e ciclos geoquímicos globais do Precambriano e início do Paleozoico. Com o objetivo de aprimorar os modelos existentes de planícies de inundação pré-vegetação, desenvolvidos antes da evolução de plantas vasculares no continente, três exemplos de ambientes aluviais foram investigados com o emprego de análise de fácies e de elementos arquiteturais. Os exemplos escolhidos oferecem a oportunidade de avaliar não apenas a existência destes depósitos sedimentares, mas também de propor um modelo para a deposição deste ambiente sedimentar particular. A Formação Tombador (Supergrupo Espinhaço, BA) é parte de espessa sucessão sedimentar de idade Mesoproterozoica, que inclui depósitos aluviais e costeiros; O Grupo Santa Bárbara e o Grupo Guaritas (Supergrupo Camaquã, RS), que se estendem do fim do Neoproterozoico ao início do Cambriano, representam sucessões aluvias depositadas em rift continental. O estudo destes três exemplos permitiu a determinação de possíveis feições comuns a planícies de inundação pré-vegetação, como depósitos de granulação relativamente mais grossa em comparação a exemplos modernos, melhor preservação de estruturas sedimentares e abundância de facies arenosas representativas de condições de fluxo e sedimentação desconfinadas. Os exemplos de planícies de inundação pré-vegetação utilizadas para compor este modelo simplificado compartilham de semelhanças marcantes a depósitos de rios efêmeros, que são frequentemente citados como explicação para a formação de espessos depósitos de arenitos-em-lençól. A reavaliação de depósitos fluviais pré-vegetação, considerando a possibilidade de que planícies de inundação de granulação grossa, sugere que este ambiente deposicional tem sido bastante negligenciado, e que inferências climáticas obtidas da alternância de estilos fluviais contrastantes pode ser equivocada, uma vez que a alternância de registro de rios perenes e efêmeros podem ser parte de um mesmo sistema deposicional.Floodplains are areas of unconfined and episodic water flow that, given the generalized availability of water, nutrients and stable substrate, have been extensively affected by the first appearance and subsequent evolution of land plants. In this respect, the scarcity of documented examples of pre-Silurian floodplain deposits contrasts with the continuous and decades-long debate on the effects of land plants evolution on fluvial channel styles. Given the importance of floodplains as sites of sediment storage, silicate minerals weathering and development of soil profiles, this lack of data on ancient floodplains has great implications for our understanding of the source-to-sink systems, the climate record and the global geochemical cycles of the Precambrian and the Early Paleozoic. Aiming at the improvement of the current models regarding pre-vegetation floodplains, which were developed prior to the evolution of vascular land plants, three examples of alluvial environments were investigated trough facies and architectural elements analysis. The used examples offer the opportunity to assess not only the existence of such deposits, but also to propose a model for the deposition of those particular sedimentary environments. The Mesoproterozoic Tombador Formation (Espinhaço Supergroup, Northeastern Brazil) is part of thick sedimentary deposits, which includes alluvial and coastal environments; the Neoproterozoic Santa Bárbara Group and the Cambrian Guaritas Group (Camaquã Basin, Southern Brazil) represents alluvial successions deposited in a continental rift system. The study of the three examples allowed the determination of some common features to pre-vegetation floodplain deposits, like relatively coarser grained deposits in comparison to modern examples, better preservation of sedimentary structures and abundance of sandstone facies representative of sedimentation in unconfined flow settings. The pre-vegetation floodplain deposits used to draw this simplified model share characteristics remarkably similar to ephemeral river deposits, which are frequently evoked to explain the formation of thick successions of sheet-like sandstone deposits. The re-evaluation of pre-vegetation fluvial deposits considering the possibility of coarse grained floodplains suggests that this environment have been greatly overlooked, and that climate inferred from the alternation of contrasting fluvial styles might be misleading, since alternation of deposits representing perennial and ephemeral fluvial deposits can be part of the same depositional system.
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Amarante, Francyne Bochi do. "Arquitetura de fácies e evolução estratigráfica da For-Mação Tacuarembó, Bacia Norte – UY." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2017. http://hdl.handle.net/10183/153394.
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A Formação Tacuarembó (Jurássico Superior – Cretáceo Inferior), subdividida em Membro Batoví e Membro Rivera, aflora na região norte do Uruguai, nos departamentos de Rivera e Tacuarembó. O objetivo principal deste trabalho é a análise sedimentológica e estratigráfi-ca da Formação Tacuarembó, através da caracterização faciológica, a reconstrução dos modelos deposicionais e a definição das relações de contato entre os membros Batoví e Rivera. Para alcançar tal objetivo, foi realizado o levantamento, na escala 1:50, de um tes-temunho e de quarenta e uma seções colunares, estas divididas em sete transectas com base em sua distribuição espacial. Como resultado, foram detalhadas litofácies posterior-mente agrupadas em diferentes associações de fácies. O Membro Batoví é constituído por associações de fácies de (1) dunas eólicas, (2) lençóis de areia eólicos, (3) canais fluviais efêmeros, (4) canais fluviais perenes entrelaçados e (5) deltas. O Membro Rivera, por sua vez, é constituído essencialmente por associações de fácies de dunas eólicas. A intercala-ção entre depósitos fluviais, eólicos e deltaicos, com predominância de associações fluviais sugere que o Membro Batoví representa o modelo deposicional de porção distal de um sis-tema fluvial distributário Já o Membro Rivera caracteriza-se pelo sucessivo cavalgamento de dunas eólicas, sem a ocorrência de depósitos de interdunas úmidas ou encharcadas, definindo um sistema eólico seco. A mudança abrupta de sistemas deposicionais, marcada por uma superfície plana, por vezes com concentração de clastos, indica a existência de uma discordância entre os membros Batoví e Rivera. Aliado a isto, a mudança no modelo deposicional sugere uma alteração climática, passando de um clima arido a semi-árido du-rante a deposição do Membro Batoví, para um clima hiperárido ao longo da deposição do Membro Rivera.The Tacuarembó Formation (Upper Jurassic - Lower Cretaceous), subdivided into Batoví Member and Rivera Member, crops in the northern region of Uruguay, in the Rivera and Tacuarembó departments. The main objective of the present work is the sedimentological and estratigraphic analysis of the Tacuarembó Formation, through the faciological charac-terization, reconstruction of the depositional models and definition of contact relations be-tween the Batoví and Rivera members. To reach such objective, a well-log and forty-one columnar sections were surveyed in a scale 1:50, and later the columnar sections were di-vided into seven transects, based on their spatial position. As a result, lithofacies were de-tailed and later grouped in different facies associations.The Batoví Member consists of associations of facies of (1) eolian dunes, (2) eolian sand sheets, (3) ephemeral fluvial channels, (4) perennial braided fluvial channels and (5) deltaic. On the other hand, the Ri-vera Member, is essentially constituted by facies associations eolian dunes. The intercala-tion between fluvial, eolian and deltaic deposits, with predominance of fluvial associations, suggests that the Batoví Member represents the depositional model of the distal portion of a distributary fluvial system. Contrastingly, the Rivera Member is characterized by the suc-cessive eolian dunes climbing, without the occurrence of wet or damp interdunes deposits, defining a dry eolian system. The abrupt change of depositional systems, marked by a flat surface, sometimes with clasts concentration, indicates the existence of an unconformity between the members Batoví and Rivera. Allied to this, the change in the depositional model suggests a climatic change, going from arid to semi-arid climate during the deposi-tion of the Batoví Member, to a hyperarid climate during the deposition of the Rivera Mem-ber.
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Hamshaw, Scott Douglas. "Fluvial Processes in Motion: Measuring Bank Erosion and Suspended Sediment Flux using Advanced Geomatic Methods and Machine Learning." ScholarWorks @ UVM, 2018. https://scholarworks.uvm.edu/graddis/827.
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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.
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Simms, Andrew. "Sedimentological and architectural aspects of dryland fluvial systems, modern analogues to the triassic deposits of the Tern Field, northern North Sea." Thesis, University of Aberdeen, 2005. http://digitool.abdn.ac.uk/R?func=search-advanced-go&find_code1=WSN&request1=AAIU200336.
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This study examines two Modern outcrop analogues to the Cormorant Formation of the Tern Field are in order to delimit controls on architectural development. Ground-truthing of a whole-rock trace element geochemical correlation technique is also undertaken in order to understand the processes controlling perceived correlations in similar studies on sub-surface data. The Huab River in Namibia is a Modern dryland fluvial system experiencing the development of a channel fan. Detailed sedimentary logging of the fan feature reveals a systematic variation in facies, from high net-to-gross deposits in the upstream portion to low net-to-gross deposits in the downstream portion. The Plio-Pleistocene deposits of the ancestral Rio Grande in New Mexico provide an example of a dryland fluvial system developed in an active rift setting with structural context preserved throughout the area. A systematic facies variation throughout the basins is identified and related to a structural control and reveals confinement of the fluvial system close to the bounding fault in the Palomas Basin. In the Hatch-Rincon Basin facies variations from high net:gross deposits in the basin centre to low net:gross deposits in the basin margin reflect subsidence upon two bounding faults. Sedimentological analysis of three cores from the Triassic Cormorant Formation divides the succession into three facies packages. Data from the two field analogues is utilised in constructing two depositional models and two architectural models. A terminal fan model and a typical through-draining braided fluvial system are envisaged as possible depositional mechanisms. Ground-truthing of a whole-rock trace element correlation technique was carried out in both field analogues. A grainsize control upon whole-rock trace element concentration is identified in both field areas, potentially limiting the ability of the technique to be responsive to provenance. This study shows that research in areas where depositional context is preserved can provide unambiguous data that is not available in ancient studies.
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Botalova, Oxana [Verfasser]. "Characterization of organic contaminants in industrial wastewaters from direct discharges and their behavior in fluvial systems of North Rhine-Westphalia / Oxana Botalova." Aachen : Hochschulbibliothek der Rheinisch-Westfälischen Technischen Hochschule Aachen, 2011. http://d-nb.info/1018227857/34.
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Jones, Neville Edward. "Controls on late stage fluvial systems in foreland basins : an example from the tertiary Digne-Valensole Basin of the external French Alps." Thesis, University of Liverpool, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.367698.
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Deschamps, Rémy. "Architectures et facteurs de contrôle des systèmes fluviatiles et turbiditiques. De la caractérisation à la modélisation." Electronic Thesis or Diss., Sorbonne université, 2018. http://www.theses.fr/2018SORUS611.
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Les systèmes turbiditiques et fluviatiles présentent des similitudes, notamment dans leur morphologie (incisions, chenaux), mais de nombreuses différences sont notables, en ce qui concerne l’architecture des dépôts, et l’évolution spatio-temporelle de ces deux systèmes, pourtant génétiquement liés. La comparaison de ces systèmes porte sur l’interaction des différents processus physiques impliqués dans la mise en place et dans le fonctionnement de ces systèmes, et sur les architectures des dépôts préservés. Les systèmes continentaux et marins profonds sont caractérisés d’abord par les processus physiques conduisant à l’érosion, au transport puis au dépôt des particules sédimentaires. Ces processus sont contrôlés par divers forçages locaux ou globaux, façonnant ainsi leurs morphologies qui évolue dans l’espace (le long du profil amont-aval), et dans le temps. Ces systèmes sont génétiquement liés et l’approche « source-to-sink » comprends l’ensemble des processus continentaux et marins qui contribuent à la production, au transport et au dépôt des sédiments. La compréhension de ces facteurs de contrôles est essentielle pour comprendre et prédire la sédimentation enregistrée dans les bassins à différentes échelles. L’ensemble de ces paramètres est responsable de l’organisation interne des réservoirs sableux, et la compréhension de ces différents paramètres vont permettre de contraindre les modèles numériques, dont l’objectif est, selon l’échelle considérée (bassin ou réservoir), de prédire la distribution des faciès sédimentaires (réservoirs, roches mères, couvertures), ou de minimiser les risques lors de l’exploitation d’un réservoirThe turbiditic and fluvial systems have similarities, in particular in their morphology (incisions, channels), but many differences are notable, as regards the architecture of the deposits, and the spatio-temporal evolution of these two systems, yet genetically linked. The comparison of these systems concerns the interaction of the different physical processes involved in the origin and the behaviour of these systems, and on the architectures of the preserved deposits. Continental and deep sea systems are characterized primarily by the physical processes leading to the erosion, transport and subsequent deposition of sedimentary particles. These processes are controlled by various local or global forcing, thus shaping their morphologies that evolves in space (along the upstream-downstream profile), and over time. These systems are genetically linked and the "source-to-sink" approach includes all the continental and marine processes that contribute to sediment production, transport and deposition. Understanding these controlling factors is crucial in the understanding and the prediction of sedimentation recorded in basins, at different scales. The allocyclic and the autocyclic controlling factors are responsible for the internal organization of the sandy reservoirs, and the understanding of these different parameters will make it possible to constrain the numerical models, whose objective is, according to the scale considered (basin scale or reservoir scale), to predict the distribution of sedimentary facies (reservoirs, source rocks, seals), or to minimize the risks when producing a reservoir
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Hoffmann, Bernd [Verfasser], and Dirk [Akademischer Betreuer] Sachse. "Plant organic matter mobilization and export in fluvial systems : a case study from the eastern Nepalese Arun Valley / Bernd Hoffmann ; Betreuer: Dirk Sachse." Potsdam : Universität Potsdam, 2016. http://d-nb.info/1218401079/34.
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Denson, Robyn L. "A conceptual methodology for studying the geoarchaeology of fluvial systems : with case studies from the Oklawaha River (Florida) and the River Earn (Scotland)." Thesis, University of St Andrews, 1995. http://hdl.handle.net/10023/15148.
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This thesis explores a conceptual methodology for studying archaeological sites in fluvial settings. The methodology stems from geoarchaeology, an approach to the past that focuses upon the geomorphic context of artifacts or the application of geological principles and techniques to the solution of archaeological problems. The paper will examine its application to fluvial systems in two different geomorphic environments, the Oklawaha River in Florida and the Earn River Valley in Scotland. In these different environmental settings, the geoarchaeological approach makes use of different kinds of evidence available to it. Survey in submerged and eroding river margins offers additional information on site distribution and density within the landscape that can go unnoticed by traditional terrestrial surveys. Through conceptualization and application of the methodology that has developed from these studies, the arbitrary land/water interface can effectively be erased from research areas and rivers can begin to be viewed not as permanent and non-moving barriers, but as significant and dynamic components of the archaeological landscape.
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Luz, Rodolfo Alves da. "Geomorfologia da planície fluvial do rio Pinheiros entre os bairros de Pinheiros, Butantã e Cidade Jardim, São Paulo (SP)." Universidade de São Paulo, 2010. http://www.teses.usp.br/teses/disponiveis/8/8135/tde-03112010-093445/.
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Na presente pesquisa investiga-se a geomorfologia da planície fluvial do rio Pinheiros entre os bairros de Pinheiros, Butantã e Cidade Jardim, na cidade de São Paulo. Para tal, propõe-se uma carta geomorfológica de detalhe deste setor da planície na escala de 1:20.000, confeccionada a partir de pesquisa arquivística prévia e, principalmente, de fotografias aéreas e de mapas antigos. A análise da carta e a sua correlação com informações sedimentológicas e estratigráficas encontradas, principalmente, em recentes relatórios de engenharia para a construção do Metrô de São Paulo, permitem a caracterização do sistema fluvial deste setor do rio Pinheiros, bem como de parte da morfodinâmica atuante no sistema antes da perturbação antrópica de alto impacto decorrente da urbanização que ali se instalou a partir da década de 1930. A pesquisa permitiu também a interpretação de uma provável sequência de eventos geomorfológicos atuantes no setor estudado durante o Pleistoceno Superior e o Holoceno. Parâmetros morfométricos tais como índice de sinuosidade de canais e paleocanais e largura da planície no trecho estudado evidenciaram aspectos da influência da estrutura geológica em sua evolução. O reconhecimento de sistemas geomorfológicos em seu estágio préperturbação antrópica é essencial para a compreensão dos processos atuais, principalmente em meios intensamente modificados como as áreas urbanas. A pesquisa apresenta então este tipo de reconhecimento, colaborando assim na compreensão dos processos antecedentes às grandes rupturas que se instalam no sistema a partir das ações antrópicas na superfície.This research investigates the geomorphology of part of Pinheiros River fluvial plain in São Paulo city. This study main result is a detailed geomorphologic map - 1:20,000 - that used ancient aerial photographs and maps obtained from formal archival surveys. The descriptions of floodplain units were associated to stratigraphic and sedimentologic data obtained from recent engineering projects reports of São Paulo underground (such as subway). This association allows the understanding of part of Pinheiros River fluvial system and morphodynamic before urbanization. The research also allowed offering a sequence of geomorphological events related to the floodplain and channel systems over the Holocene. Morphometric parameters, such as width and sinuosity index of channels and paleo-channels of floodplain meandering system, appear as an evidence of the structural influence in geomorphological evolution of this system. The recognition of geomorphologic systems in pre-disturbance stage is essential for understanding the current processes, mainly in environments greatly modified by human actions, such as urban areas. This research presents this kind of recognition and contributes to the understanding of processes in the system before human actions in the surface.
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Harjung, Astrid. "Impact of drought periods on carbon processing across surface-hyporheic interfaces in fluvial systems = Impacte dels períodes de sequera sobre el processat de carboni a través de la interfase superficial i zona hiporreica en sistemes fluvials." Doctoral thesis, Universitat de Barcelona, 2018. http://hdl.handle.net/10803/586040.
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Headwater streams essentially link the terrestrial and the aquatic carbon cycle because they transport terrestrial organic and inorganic carbon downstream towards the oceans. However, most of these inputs are processed during this journey. These processes include down-break of particulate organic matter, transformation and respiration of dissolved organic matter and furthermore, in-stream production of organic matter. In particular, during drought periods the aquatic processes gain importance because terrestrial inputs are diminished. Therefore, carbon cycling in the remaining surface and subsurface flow of the main channel is accelerated and driven by the connectivity of these compartments. As the surface flow ceases carbon processing rates along subsurface flow paths, namely the hyporheic zone, increase.
In the light of climate change, longer drought periods, including in currently humid areas, are expected. Within this context, this thesis aims to understand carbon processing across the surface-hyporheic interface of a Mediterranean intermittent stream during a summer drought. Since dissolved organic matter represents the key energy source of aquatic metabolism that ultimately determine in-stream carbon cycling, we focused on the organic matter quantity and quality. We found increasing retention rates of dissolved organic matter along hyporheic flowpaths as water residence time in this compartment increases with the ceasing of surface flow. The evaluation of optical indices of dissolved organic matter quality revealed that the molecular weight decreased and indices related to biological activity increased. Furthermore, we showed that dissolved organic matter from primary production is rapidly respired in the remaining surface water, while humic-like compounds are processed and respired in the hyporheic zone. The dissolved organic matter processing in the hyporheic zone was paralleled with observations of disproportional high partial pressure of CO2 in the interstitial pore water. These CO2 pulses were related to the desiccation of the streambed, as well as dissolved organic matter availability. Our results suggested that the hyporheic zone acts as a humid refuge for microbial activity and that respiration activity immediately restarts when rain events reestablish subsurface flow paths. Associated with this microbial activity, during drought the processing rates of dissolved organic matter, as well as the processing rates of inorganic nutrients were enhanced. Moreover, we explored the effects of a summer drought on subalpine streams by applying different discharge levels in stream-side flumes fed by the water of a subalpine stream. In this experiment, we found high dissolved organic carbon release from in-stream processes in the flumes with the lowest discharges. This dissolved organic carbon release was at the beginning paralleled with a transient increase in gross primary production but continued to rise even when primary production collapsed. While the collapse of primary production might be a consequence of phosphor limitation, respiration and degradation of dissolved and particulate organic matter in the sediment continued throughout.
In line with our findings from the Mediterranean stream, this mesocosm experiment highlighted the importance of the hyporheic zone and organic matter stored therein for carbon processing during drought periods. In both study sites, the surface water metabolism was ultimately dominated by respiration, and dissolved organic matter quality of the surface water played an important role on processes in the hyporheic zone. Although the investigated study sites were different in many aspects we found surprising similarities in carbon processing with flow reduction. This suggests that findings from Mediterranean streams might be transferable to other climatic regions under global change scenarios.Els rius de capçalera connecten essencialment el cicle del carboni terrestre i aquàtic, donat que transporten el carboni orgànic i inorgànic terrestre aigües avall. Durant els períodes de sequera, els processos aquàtics guanyen importància perquè les aportacions terrestres es redueixen. A mesura que l’aigua de la superfície desapareix, les taxes de processament de carboni al llarg de la zona hiporreica augmenta. Atès que, la matèria orgànica dissolta és la principal font d'energia del metabolisme aquàtic que, en aquesta tesis se centra en la quantitat i la qualitat de la matèria orgànica. Hem trobat un augment de la retenció de la matèria orgànica dissolta en medi hiporreic, ja que el temps de residència de l'aigua en aquest compartiment augmenta amb el cessament de aigües superficials. L'avaluació dels índexs òptics de la qualitat de la matèria orgànica dissolta va revelar que el pes molecular es va reduir, i es van incrementar els índexs relacionats amb l'activitat biològica. Vam demostrar que la matèria orgànica dissolta de la producció primària es respira ràpidament en l'aigua superficial restant, mentre que els compostos més húmics es processen i es respiren a la zona hiporreica. Els nostres resultats suggereixen que la zona hiporreica actua com un refugi humit per a l'activitat microbiana i que l'activitat de la respiració es reinicia immediatament quan els esdeveniments de pluja restableixen el flux hyporheic. A més a més, es van explorar els efectes d'una sequera en rius de capçalera subalpins aplicant diferents nivells de caudal en mesocosms. En aquest experiment, vam trobar una elevada alliberació de carboni orgànic dissolt fruit dels processos aquàtics en els mesocosms de cabals més baixos. Al principi, aquest augment de carboni orgànic dissolt va anar acompanyat per un increment transitori de la producció primària bruta, però va continuar augmentant fins i tot quan la producció primària es va col·lapsar. En els dos llocs d'estudi, el metabolisme de l'aigua superficial va estar dominat per la respiració; i la qualitat de la matèria orgànica dissolta de l'aigua superficial va jugar un paper important en els processos de la zona hiporreica.
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Fagundes, Marcelo. "Sistema de assentamento e tecnologia lítica: organização tecnológica e variabilidade no registro arqueológico em Xingó, Baixo São Francisco, Brasil." Universidade de São Paulo, 2007. http://www.teses.usp.br/teses/disponiveis/71/71131/tde-25022011-112317/.
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A presente tese tem como objetivo apresentar os resultados alcançados por meio de pesquisas sistemáticas de campo, laboratório e gabinete, que interligadas coligiram dados responsáveis uma compreensão mais assertiva sobre o modo de vida e dinâmica cultural dos grupos pré-históricos que ocuparam a Área Arqueológica de Xingó durante quase oito milênios. A pesquisa baseou-se em diferentes posicionamentos teóricos, tendo como foco as indústrias líticas evidenciadas e coletadas em dezesseis sítios arqueológicos, todos da área 03 de Xingó. Essa característica foi fundamental e nos permitiram inferir com maior segurança sobre as diferentes escolhas/estratégias envolvidas para concepção e manufatura dos conjuntos artefatuais (similaridades e diferenças), porém sempre cerceando a possibilidade de compreensão de como as populações pré-históricas que ocuparam a região estabeleceram seu sistema regional de assentamentos em terraço, tendo como hipótese norteadora que todos os sítios contemporâneos estariam conectados entre si no chamado complexo situacional de sítios. Metodologicamente, nossos dados foram sistematizados por meio da análise dos atributos formais e tecnológicos das indústrias líticas e de técnicas estatístico-comparativas, de forma que nos possibilitou reconstruir, mesmo que parcialmente, as seqüências operacionais dessa cultura material, inclusive partindo do pressuposto de variabilidade isocréstica. Em relação ao referencial teórico, foram utilizados múltiplos conceitos e abordagens que convergiram para a compreensão da paisagem enquanto construção social que, dotada de valores e significados, foi ser compreendida como o loci de ocupação continuada, ou lugares persistentes.This thesis presents the final results of a long-term study after systematic research in field, in laboratory and in office that interconnected unify data which give us an assertive understanding of the life and cultural dynamic of prehistoric societies who occupied the Archaeological Zone of Xingo during eight thousand years. The research is based in different theoretical approaches, but focusing the lithic assemblage revealed and collected in sixteen archaeological sites, all of them into the included in the Area 3 of Xingo. These different approaches were essential in this research, giving me the opportunity to infer with security the differences on the co-participating strategies related to the conception and manufacture of the artefactual assemblages (similarities and differences), hence delimitating the possibility to understand how the Xingo an prehistoric populations established their regional settlement system on the fluvial benches. I used as a guide hypothesis the fact that all contemporaneous sites were connected among them in a situational complex of sites. Methodologically, my data was systematized through of formal analysis of the morphological and technological attributes of the lithic assemblages and through statistical-comparative techniques, which helped me to reconstruct partially the operational sequences of the material culture manufacture, including the isocrestic variability. In relation to my theoretical frames, I used multiples concepts and approaches that worked together to understand the landscape while a social construction immersed in social means and values which have been understood as a loci of continuous occupation or persistent places
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Majeski, Adam L. "Fluvial Systems Tied Together Through a Common Base Level: The Geomorphic Response of the Dirty Devil River, North Wash Creek, and the Colorado River to the Rapid Base Level Drop of Lake Powell." DigitalCommons@USU, 2009. https://digitalcommons.usu.edu/etd/291.
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Fluvial adjustment to base level change has its roots in the fundamental concepts of geomorphology. This thesis explores the rate of erosion and sedimentation on the Colorado and Dirty Devil rivers and North Wash Creek under the current base level changes related to the drawdown conditions of Lake Powell. Through cross section and long profile resurveys, the current state of each system is captured and added to the historic record of sedimentation in Lake Powell. All three systems are generally forming narrow and deep incised channels driven by the rapid rate of base level fall. Cross sections that deviate from this are due to site-specific factors, such as channel armoring, the presence of local base levels, or bedrock canyon width in relation to active channel width. In all systems, sediment is being transported through the establishing fluvial regime and is deposited at or below the new base level. This has caused rapid downstream progradation of each delta front. The volume of sediment accumulation and erosion and rates through time are calculated for each system. Deposit volume is proportional to each systems drainage basin area, as are the rates and magnitudes of deposition and erosion. The percentage of sediment eroded versus deposited shows an inverse relationship, with North Wash eroding the greatest percentage of its delta. Field observations and repeat photography on the distribution, orientation, and activity of lateral slumping and mud cracks identify that thick beds of fine-grained and cohesive silts and clays are necessary for these features to form. These features act to destabilize sediment and, in the case of bank failure, deliver it directly to the channel.
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Venus, Joanne Helen. "Tectono-stratigraphic evolution of fluvial and aeolian systems in a salt mini-basin province during changing climatic conditions : Permian Undifferentiated Cutler Group, South East Utah, USA." Thesis, University of Leeds, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.597094.
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The Permian Cutler Group in the northwest part of the Paradox foreland basin of south-eastern Utah and south-western Colorado comprises a succession of conglomerate and sandstone of mixed fluvial and aeolian affinity up to 4000 m thick: the proximal and medial parts of this basin-fill succession are the focus of this study. Fluctuations in climate and sediment flux resulted in growth and recession of penecontemporaneously operating fluvial and aeolian systems. Fluvial sediment was sourced from the Uncompahgre Uplift of the Ancestral Rocky Mountains. Progressive loading and movement of older salt deposits during accumulation of the Cutler Group generated a series of salt-wall-bounded mini-basins, collectively known as the “Salt Anticline Region~, in the eastern part of the study area. Here, the so-called Undifferentiated Cutler Group varies in thickness from zero over some salt highs to -4000 m just a few kilometres away in adjacent mini-basin depocentres. indicating that syn-sedimentary salt movement generated Significant variations in accommodation. In the Salt Anticline Region syn-sedimentary salt movement was the dominant control on the preserved stratigraphy and the distribution of architectural elements, which in turn was closely linked to the rate and style of influx, of sediment derived from the Uncompahgre Uplift. During tectonically quiescent episodes, fluvial systems filled accommodation in mini-basin depocentres before establishing flow pathways over buried salt-wall highs. In the Shafer Basin, in the western part of the study area, subtle salt structures form low-amplitude, long-wavelength anticlines upon which architectural elements thin and pinch out. Aeolian elements are rare in the Salt Anticline Region, but more common in medial parts of the Paradox Basin. Here, styles of aeolian-fluvial interaction occur at three scales: (i) large-scale intertonguing and interbedding of fluvial and aeolian elements; (il) small-scale feathering and reworking of elements and (iii) interactions at the grain-scale. These styles of interaction demonstrate penecontemporaneous aeolian and fluvial activity and large-scale alternations between episodes of aeolian and fluvia1 dominance. The large-scale cycles between aeolian and fluvial elements were likely controlled by a combination of extrinsic climatic forcing and episodic recurrence of Uncompahgre Uplift. resulting in tectonically driven pulses of enhanced rates of sediment delivery. System interactions at smaller scales record the effects of intrinsic (autogenic) controls. whereby localized dominance of fluvial over aeolian processes (and vice versa) occurred.