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Artigos de revistas sobre o assunto "Fluvial-estuarine systems"
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Bogemans, Frieda, Mathieu Boudin, Rindert Janssens e Cecile Baeteman. "New data on the sedimentary processes and timing of the initial inundation of Lower Khuzestan (SW Iran) by the Persian Gulf". Holocene 27, n.º 4 (3 de outubro de 2016): 613–20. http://dx.doi.org/10.1177/0959683616670224.
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The early- and mid-Holocene deposits of the Lower Khuzestan plain at the north-eastern margin of the Persian Gulf have been investigated by means of facies analysis of sediment successions of undisturbed cores. Organic material and molluscs have been selected for dating by radiocarbon whereby possible contamination by hard-water effect is discussed. The results suggest that the Holocene transgression in Mesopotamia may have taken place later than generally accepted. Before ca. 7700–7900 yr cal. BP, the plain was characterized by mud-dominated fluvial systems. During the mid-Holocene, tides invaded the existing valleys, and the sedimentary environment shifted from fluvial to estuarine but not as extensively as has previously been suggested. The estuarine environments lasted for about 2000–2500 years until ca. 4850–5000 yr cal. BP when the seaward part of the plain was again characterized by widespread fluvial sedimentation.
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Gil-Díaz, Teba, Jörg Schäfer, Lionel Dutruch, Cécile Bossy, Frédérique Pougnet, Melina Abdou, Antoine Lerat-Hardy et al. "Tellurium behaviour in a major European fluvial–estuarine system (Gironde, France): fluxes, solid/liquid partitioning and bioaccumulation in wild oysters". Environmental Chemistry 16, n.º 4 (2019): 229. http://dx.doi.org/10.1071/en18226.
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Environmental contextThe environmental behaviour of tellurium is poorly understood. We investigate the transport of tellurium in both dissolved and particulate forms from the river watershed to the Gironde Estuary, where a 30-year historical record provides insight on tellurium bioaccumulation in wild oysters. These results constitute the first comprehensive study on natural tellurium behaviour in a major fluvial-estuarine system, information essential for predictive modelling of tellurium risk assessment. AbstractTellurium (Te) is a technology critical element (TCE) with largely unknown environmental behaviour, especially in continent-ocean interface systems. The unknown behaviour results from the lack of studies in aquatic environments and from analytical challenges limiting the determination of its naturally low (ultra-trace) environmental levels. We performed a comprehensive study of Te in the Lot–Garonne–Gironde fluvial–estuarine system to better understand seasonal variations, solid/liquid partitioning (Kd), gross fluxes, estuarine dynamics, and transfer to wild oysters at the estuary mouth. A temporal record (2014–2017) of dissolved (Ted) and particulate (Tep) Te concentrations at five sites in the Lot–Garonne River system shows little differences between sites, with average ~0.9ngL−1 and ~50µgkg−1 respective concentrations. Watershed Ted and Tep follow parallel seasonal patterns, which result in constant partitioning (log10 Kd ~4.75Lkg−1), with constant annual gross dissolved fluxes (~15.0kgy−1) and variable gross particulate fluxes (from 6.50 to 140kgy−1) entering the Gironde Estuary. Estuarine reactivity in contrasting hydrological conditions (from flood to drought) suggest that grain-size effects and/or estuarine hydrological residence times strongly affect Tep behaviour. Historical records (1984–2017) of Te in wild oysters at the estuary mouth vary from 1.33 to 2.89µgkg−1 dry weight (d.w.), without any clear long-term trend. This study provides rare knowledge on Te environmental dynamics in aquatic systems, and suggests that, although no current anthropogenic sources were identified in the economically developed Lot-Garonne-Gironde fluvial-estuarine system, there is a non-negligible bioaccumulation in wild oysters at the estuary mouth.
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Keough, Brandon, e Kenneth Ridgway. "High-Latitude Depositional Systems, Provenance, and Basinal Setting of the Late Cretaceous Cantwell Basin, Denali National Park and Preserve, Alaska: A Stratigraphic Framework for Paleontological and Paleoclimatic Studies". Geosciences 13, n.º 6 (15 de junho de 2023): 181. http://dx.doi.org/10.3390/geosciences13060181.
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The Cantwell Formation of the central Alaska Range provides a robust archive of high-latitude, Late Cretaceous depositional systems and paleo-floral/faunal assemblages. Our stratigraphic analysis defines two mappable members. The lower member (1500–2000 m thick) represents vegetated alluvial fan and braided fluvial systems that transition up-section to fluvial–estuarine systems that drained into an inland continental seaway. The upper member (~2000 m thick) represents estuarine–marginal marine and lacustrine systems. Previous paleontological studies demonstrate that the Cantwell basin was populated by various dinosaurs, fishes, bivalves, birds, and marginal marine micro-organisms. Integration of new and published geologic mapping allows for reconstruction of depositional systems at the basin scale and provides additional paleogeographic context. The northern basin margin was defined by a previously unrecognized south-verging thrust belt, whereas the southern margin of the basin was defined by a north-verging thrust belt inboard of an active magmatic arc. Sediment sources interpreted from U-Pb detrital zircon geochronology included the coeval magmatic arc and older Cretaceous plutons, and Proterozoic–Mesozoic strata exhumed along the basin margins. Results of our study provide a depositional, stratigraphic, and structural framework that may serve as a guide for future paleontological and paleoclimatic investigations of Late Cretaceous Arctic environments of the Cantwell basin.
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Jalón-Rojas, I., S. Schmidt e A. Sottolichio. "Turbidity in the fluvial Gironde Estuary (S–W France) based on 10 year continuous monitoring: sensitivity to hydrological conditions". Hydrology and Earth System Sciences Discussions 12, n.º 3 (10 de março de 2015): 2843–83. http://dx.doi.org/10.5194/hessd-12-2843-2015.
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Abstract. Climate change and human activities impact the volume and timing of freshwater input to estuaries. These modifications in fluvial discharges are expected to influence estuarine suspended sediment dynamics, and in particular the turbidity maximum zone (TMZ). Located in the southwest France, the Gironde fluvial-estuarine systems has an ideal context to address this issue. It is characterized by a very pronounced TMZ, a decrease in mean annual runoff in the last decade, and it is quite unique in having a long-term and high-frequency monitoring of turbidity. The effect of tide and river flow on turbidity in the fluvial estuary is detailed, focusing on dynamics related to changes in hydrological conditions (river floods, periods of low-water, inter-annual changes). Turbidity shows hysteresis loops at different time scales: during river floods and over the transitional period between the installation and expulsion of the TMZ. These hysteresis patterns, that reveal the origin of sediment, locally resuspended or transported from the watershed, may be a tool to evaluate the presence of remained mud. Statistics on turbidity data bound the range of river flow that promotes the TMZ installation in the fluvial stations. Hydrological indicators of the persistence and turbidity level of the TMZ are also defined. The long-term evolution of these indicators confirms the influence of discharge decrease on the intensification of the TMZ in tidal rivers, and provides a tool to evaluate future scenarios.
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Fitch, Simon, Ken Thomson e Vince Gaffney. "Late Pleistocene and Holocene depositional systems and the palaeogeography of the Dogger Bank, North Sea". Quaternary Research 64, n.º 2 (setembro de 2005): 185–96. http://dx.doi.org/10.1016/j.yqres.2005.03.007.
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Abstract3D seismic data from the Dogger Bank, North Sea, allow the mapping of Late Pleistocene and Holocene depositional systems in unprecedented detail. The data demonstrate that glacial processes resulted in the development of incised tunnel valley systems during the Weichselian and that these were subsequently modified by fluvial processes in a pro-glacial setting. Subsequently, the Dogger Bank formed an emergent plain during the Holocene with a complex meandering river system, associated tributary or distributary channels and lakes, dominating the region. Prior to the sea level rising sufficiently to submerge the Dogger Bank around 7500 yr ago, the meandering river system was replaced by a dendritic channel network of potential fluvial, estuarine or intertidal origin. As the Holocene depositional features bear no systematic relationship to the bathymetry this study demonstrates that previously published bathymetry-based models for the Holocene palaeogeographic development of the North Sea require modification.
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Hayes, Derek A., Scott E. Botterill, Michael J. Ranger e Murray K. Gingras. "Fluvial character and architecture of an outcrop using sedimentology combined with UAV-based modeling, Cretaceous McMurray Formation, NE Alberta, Canada". Journal of Sedimentary Research 93, n.º 5 (23 de maio de 2023): 273–92. http://dx.doi.org/10.2110/jsr.2022.039.
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ABSTRACT It is widely accepted that most occurrences of inclined heterolithic stratification (IHS) in the rock record form by laterally accreting point bars in freshwater fluvial, tidally influenced fluvial, or tidally dominated estuary channels. Despite the widespread distribution of IHS in the subsurface and outcropping strata of the lower Cretaceous McMurray Formation, the large-scale depositional architecture and lateral facies variability of these deposits remains controversial. The relatively limited lateral extent of many of the outcrops is a challenge, particularly when point-bar deposits on the scale of hundreds of meters to kilometers are interpreted in outcrops spanning anywhere from 100 to 300 meters laterally. This has in turn led researchers to leverage other datasets such as 3-D seismic to analyze the large-scale depositional architecture of the IHS, leading to two main interpretations for the IHS in the McMurray Formation: 1) a fluvially dominated environment owing to geomorphological features comparable to those in large modern fluvial systems, or 2) an estuarine environment owing to the presence of trace fossils characteristic of marine-derived faunal colonization in brackish-water settings and strong evidence of tidal modulation. The purpose of this study is to investigate the sedimentology and depositional architecture of IHS in a unique, kilometer-wide outcrop exposure of McMurray Formation strata and compare it to IHS observed at other McMurray Formation outcrops previously interpreted as estuarine channels. This is achieved by combining traditional field-based methods with Unmanned Aerial Vehicle-based outcrop modeling to create a 3-D outcrop model to visualize and analyze large point-bar geobodies deposited in a channel upwards of 25 meters deep and 750 meters wide exposed in outcrop at Crooked Rapids of the Athabasca River, west of the City of Fort McMurray. Importantly, this methodology uses bed orientation trends, paleocurrent data, and sedimentological observations to identify and map architectural elements, which constitute an eastward-accreting point bar crosscut by a southwestward-accreting counter point bar in the outcrop. The results strongly suggest that the IHS at Crooked Rapids was deposited in a freshwater fluvial environment. When compared to IHS deposited in estuarine depositional environments, fluvial IHS is driven by seasonal river discharge as opposed to the interplay between river discharge and the extent of the tidal prism. Therefore, fluvial IHS is: 1) dominantly sandstone with very minor waning-flow siltstone interbeds resulting from erosion by the succeeding freshet phase, and 2) completely devoid of bioturbation until flat-lying bar top or overbank strata is encountered. Using 3-D outcrop modeling to supplement sedimentological and ichnological observations strengthens the interpretation of complex fluvial geobodies and increases the overall understanding of the large-scale depositional architecture of point bars across the tidal–fluvial transition zone.
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Selim, Selim Saber. "Sedimentology and stratigraphic evolution of fluvial–tidal transition reservoirs: an outcrop analog for the hydrocarbon-bearing Bahariya Formation, Western Desert, Egypt". Journal of Sedimentary Research 93, n.º 1 (18 de janeiro de 2023): 50–70. http://dx.doi.org/10.2110/jsr.2021.130.
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ABSTRACT The deposits of the tidal–fluvial transition zone are one of the most significant and complicated components of marginal marine systems. Sedimentological studies of these deposits are necessary due to their heterogeneous nature, which is controlled by competing tidal and fluvial parameters. Outcrop studies are required to understand the architecture, sedimentology, and evolution of tidal–fluvial deposits. The Cenomanian upper unit of the Bahariya Formation in the northern part of the Western Desert of Egypt is a tide-dominated fluvio-estuarine deposit sourced from crystalline basement and Early Cretaceous siliciclastic sedimentary rocks that lie to the southeast and south. Based on sedimentary facies analysis and paleocurrent data, the upper Bahariya Formation is composed of six main architectural elements: 1) river-dominated, tide-influenced point bar, 2) tide-dominated, river-influenced point bar, 3) floodplain, 4) crevasse splay, 5) crevasse channel, and 6) mud plug. These elements are stacked in a multistory tidal–fluvial channel complex and associated depositional elements. The reconstructed paleochannels trend from southeast to northwest, and migrated to the east and southeast. The relative contribution of fluvial processes decreased upwards through the stacked stories, with a corresponding increase in the contribution of tidal processes that were associated with transgression. An understanding of the architecture and sedimentology of the tidal–fluvial transition from outcrop successions allows the improved characterization of tidal–fluvial point-bar reservoirs and associated elements.
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Chalov, R. S., K. M. Berkovich, G. A. Larionov e L. F. Litvin. "Study of erosion-channel systems and its components: theory, history, and practice". Geomorphology RAS, n.º 2 (26 de abril de 2019): 95–108. http://dx.doi.org/10.31857/s0435-42812019295-108.
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The article is dedicated to the 50th anniversary since the N. I. Makkaveev’s Scientific Research Laboratory for soil erosion and channel processes was organized at the Moscow University. The history of scientific school, created by N. I. Makkaveev, establishment is considered, as well as the discipline on integral erosion-depositional process and its evolution to the theory of catchment erosion-fluvial systems. The analysis of the fundamental researches performed by the Laboratory is submitted, and the application tasks in the area of soil erosion, gully erosion, channel and estuarine processes are outlined. Main directions of research are formulated, the prospects for their development are evaluated.
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Mendes, Joana, Rui Ruela, Ana Picado, João Pedro Pinheiro, Américo Soares Ribeiro, Humberto Pereira e João Miguel Dias. "Modeling Dynamic Processes of Mondego Estuary and Óbidos Lagoon Using Delft3D". Journal of Marine Science and Engineering 9, n.º 1 (15 de janeiro de 2021): 91. http://dx.doi.org/10.3390/jmse9010091.
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Estuarine systems currently face increasing pressure due to population growth, rapid economic development, and the effect of climate change, which threatens the deterioration of their water quality. This study uses an open-source model of high transferability (Delft3D), to investigate the physics and water quality dynamics, spatial variability, and interrelation of two estuarine systems of the Portuguese west coast: Mondego Estuary and Óbidos Lagoon. In this context, the Delft3D was successfully implemented and validated for both systems through model-observation comparisons and further explored using realistically forced and process-oriented experiments. Model results show (1) high accuracy to predict the local hydrodynamics and fair accuracy to predict the transport and water quality of both systems; (2) the importance of the local geomorphology and estuary dimensions in the tidal propagation and asymmetry; (3) Mondego Estuary (except for the south arm) has a higher water volume exchange with the adjacent ocean when compared to Óbidos Lagoon, resulting from the highest fluvial discharge that contributes to a better water renewal; (4) the dissolved oxygen (DO) varies with water temperature and salinity differently for both systems. On the one hand, for Mondego Estuary during winter the DO levels mainly fluctuate with salinity. On the other hand, for Óbidos Lagoon, DO distribution is determined by both water temperature and salinity. During summer, the high residence time and water temperature limit the DO levels in both systems. The high transferability and superior stability of Delft3D make this model a foundation for realistic simulation and research of distinct estuarine systems, giving support to their maintenance and restoration.
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Shawler, Justin L., Christopher J. Hein, Elizabeth A. Canuel, James M. Kaste, Gregory G. Fitzsimons, Ioannis Y. Georgiou e Debra A. Willard. "Tidal erosion and upstream sediment trapping modulate records of land-use change in a formerly glaciated New England estuary". Anthropocene Coasts 2, n.º 1 (1 de janeiro de 2019): 340–61. http://dx.doi.org/10.1139/anc-2018-0034.
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Land clearing, river impoundments, and other human modifications to the upland landscape and within estuarine systems can drive coastal change at local to regional scales. However, as compared with mid-latitude coasts, the impacts of human modifications along sediment-starved formerly glaciated coastal landscapes are relatively understudied. To address this gap, we present a late-Holocene record of changing sediment accumulation rates and sediment sources from sediment cores collected across a tidal flat in the Merrimack River estuary (Mass., USA). We pair sedimentology, geochronology, bulk- and stable-isotope organic geochemistry, and hydrodynamic simulations with historical data to evaluate human and natural impacts on coastal sediment fluxes. During the 17th to 19th centuries, accumulation rates increased by an order of magnitude in the central tidal flat, likely in response to enhanced delivery of terrestrial sediment resulting from upland deforestation. However, the overall increase in accumulation (0.56–2.6 mm/year) within the estuary is subtle and spatially variable across the tidal flats because of coincident anthropogenic land clearing and dam building, upland sediment storage, and estuarine hydrodynamics. This study provides insight into the response of formerly glaciated fluvial-coastal systems to human modifications, and underscores the role of estuarine environmental conditions in modifying upland signals of land-use change.
Teses / dissertações sobre o assunto "Fluvial-estuarine systems"
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Laneville, Michael Warren. "Subsurface Depositional Systems Analysis of the Cambrian Eau Claire Formation in Western Ohio". Bowling Green State University / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu154220482332536.
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Ferchiche, Florian. "Dynamique de la composition de la matière organique particulaire à l’interface continent-océan". Electronic Thesis or Diss., Bordeaux, 2024. http://www.theses.fr/2024BORD0429.
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La matière organique particulaire (MOP) joue un rôle clef dans le fonctionnement des écosystèmes constituant le continuum aquatique continent-océan. La MOP peut être composée de plusieurs sources produites in situ (phytoplancton, microphytobenthos, macroalgues) ou importées depuis les écosystèmes adjacents (MOP terrestre, MOP anthropique, phytoplancton fluvial, estuarien ou marin). Le long du continuum fluvio-estuarien, les proportions de chaque source dans la composition de la MOP varient au cours des saisons et entre les écosystèmes, fortement influencées par des processus environnementaux (ex. production primaire, sédimentation / remise en suspension, reminéralisation). L’objectif de cette thèse est d’améliorer (1) la caractérisation des signatures isotopiques et élémentaires des sources de MOP, (2) la quantification de la composition de la MOP provenant des fleuves et étant transformée dans les systèmes estuariens, (3) la description de la variabilité spatio-temporelle de la MOP et (4) la compréhension des forçages environnementaux à cette variabilité. Pour ce faire, la composition de la MOP a été estimée à l’aide de modèles de mélanges sur vingt-quatre systèmes fluvio-estuariens tempérés en utilisant les rapports isotopiques et élémentaires du carbone et de l’azote (δ13C, δ15N et C/N), ainsi que de l’hydrogène comme travail méthodologique prospectif (δ2Hn). La variabilité spatio-temporelle de chacune des sources de la MOP a ensuite été liée à des paramètres environnementaux à l’aide de statistiques multivariées pour en déterminer les forçages. Enfin, une comparaison des systèmes au regard de la dynamique de la composition de la MOP a été proposée. Quatre types ont été identifiés parmi les vingt-trois fleuves étudiés : (1) les fleuves à la MOP dominée par du matériel terrestre labile sur le cycle annuel, (2) les fleuves dont la MOP est composée de matériel terrestre labile et de phytoplancton, avec une saisonnalité marquée due à des efflorescences saisonnières ou bien (3) sans saisonnalité marquée, et enfin (4) les fleuves à la MOP composée de MOP terrestre labile, réfractaire et de phytoplancton, en lien avec des conditions saisonnières contrastées. Les cinq estuaires étudiés présentent des dynamiques de compositions de MOP contrastées. Dans l’Elorn et la Leyre la MOP fluviale est remplacée aux faibles salinités par du phytoplancton produit dans l’estuaire toute l’année. L’Aulne fonctionne de manière similaire mais transporte plus en aval la MOP fluviale dans des conditions hivernales. L’estuaire de la Loire présente une MOP composée uniquement de MOP autotrophe, vivante au printemps ou dégradée en hiver. Enfin, l’estuaire de la Gironde présente une MOP dominée par du matériel terrestre réfractaire sur tout le cycle annuel. Le long du continuum fluvio-estuarien, la MOP fluviale présente une composition et une dynamique spatio-temporelle contrastée. Cette MOP apportée par les fleuves voit sa composition ensuite transformée le long de l’estuaire sous une forme réfractaire par dégradation et/ou est additionnée de MOP vivante autotrophe produite in situParticulate organic matter (POM) plays a key role in the functioning of the ecosystems of the continent-ocean aquatic continuum. POM can be composed of several sources produced in situ (phytoplankton, microphytobenthos, macroalgae) or imported from adjacent ecosystems (terrestrial POM, anthropogenic POM, river, estuarine or marine phytoplankton). Along the fluvial-estuarine continuum, the contribution of each source to the composition of POM varies seasonally and between ecosystems and is strongly influenced by environmental processes (e.g., primary production, deposition-resuspension, remineralisation). This thesis aims to improve (1) the characterisation of the isotopic and elemental signatures of POM sources, (2) the quantification of the composition of POM originating from rivers and being transformed in estuarine systems, (3) the description of the spatiotemporal variability of POM and (4) the understanding of the environmental forcings of this variability. To this end, the composition of POM was estimated using mixing models over twenty-four temperate fluvial-estuarine systems using isotopic and elemental ratios of carbon and nitrogen (δ13C, δ15N and C/N), as well as hydrogen as prospective methodological work (δ2Hn). The spatiotemporal variability of each of the POM sources was then linked to environmental parameters using multivariate statistics to determine their forcings. Finally, a comparison of systems based on the dynamics of POM composition was proposed. Four types were identified among the twenty-three rivers studied: (1) rivers with POM dominated by labile terrestrial material over the annual cycle, (2) rivers with POM composed of labile terrestrial material and phytoplankton, with marked seasonality due to seasonal blooms or (3) with no marked seasonality, and finally (4) rivers with POM composed of labile terrestrial POM, refractory POM and phytoplankton, linked to contrasting seasonal conditions. The five estuaries studied showed contrasting dynamics in terms of POM composition. In the Elorn and Leyre, riverine POM is replaced at low salinity by phytoplankton produced in the estuary throughout the year. The Aulne functioning is similar but there is a transport of riverine POM further downstream during winter. The Loire estuary POM is composed solely of autotrophic POM, alive in spring or degraded in winter. Finally, the Gironde estuary POM is dominated by refractory terrestrial material throughout the annual cycle. Along the fluvial-estuarine continuum, the fluvial POM has a contrasting composition and spatio-temporal dynamics. The composition of this river-borne POM is then transformed along the estuary into a refractory form by degradation and/or is supplemented by autotrophic living POM produced in situ
Capítulos de livros sobre o assunto "Fluvial-estuarine systems"
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Barineau*, Clinton, e Diana Ortega-Ariza*. "An Upper Cretaceous paleodrainage system on the Coastal Plain unconformity of Alabama-Georgia". In Field Excursions from the 2021 GSA Section Meetings, 35–60. Geological Society of America, 2021. http://dx.doi.org/10.1130/2021.0061(03).
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ABSTRACT Rocks of the Upper Cretaceous Tuscaloosa Formation (Cenomanian) and Eutaw Formation (Santonian) in southwestern Georgia and southeastern Alabama record an interval of fluvial and nearshore marine deposition. In the vicinity of Columbus, Georgia, basal units of the Tuscaloosa Formation consist of a residual paleosol built on crystalline rocks of the Appalachian Piedmont covered by conglomeratic sandstones deposited in braided stream systems flowing across the mid-Cenomanian Coastal Plain unconformity. The unconformity, which separates Cretaceous detrital rocks from underlying metamorphic rocks and residual paleosols built on those metamorphic rocks, lies primarily within the Tuscaloosa Formation in this region and is marked at the modern surface by the geomorphic Fall Line. Mapping of the unconformity across the region reveals areas of significant paleorelief associated with a number of distinct paleovalleys incised into the mid-Cenomanian surface. The most distinct of these lie immediately east of the Alabama-Georgia state line, within 15 km of the modern Lower Chattahoochee River Valley. Spatially, these distinct paleovalleys lie immediately north of a Santonian estuarine environment recorded in the Eutaw Formation, disconformably above the Tuscaloosa Formation. Collectively, paleo-valleys in the mid-Cenomanian surface, the fluvial nature of the Tuscaloosa Formation in southwestern Georgia and southeastern Alabama, and the estuarine environment in the younger Eutaw Formation suggest a persistent (~10 m.y.) paleodrainage system that may be a forerunner to the modern Chattahoochee River.
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Kasse, C., e S. Bohncke. "Early Pleistocene fluvial and estuarine records of climate change in the southern Netherlands and northern Belgium". In River Basin Sediment Systems - Archives of Environmental Change. Taylor & Francis, 2001. http://dx.doi.org/10.1201/9781439824672.pt3.
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Ribeiro, S. R., R. A. Alves e F. M. Matias. "MORPHOLOGICAL CHANGES IN THE SERINGÃO CHANNEL, NORTHERN BRAZIL, FROM 1945 TO 2014". In Open Science Research XV, 180–88. Editora Científica Digital, 2024. http://dx.doi.org/10.37885/240616813.
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In fluvial systems, morphodynamics manifest through erosion, transport, and deposition processes, shaped by seasonal and hydrological variations, thereby modifying channel morphology. Conversely, in coastal environments, tidal influences introduce a diurnal element, further destabilizing channel morphology. The Seringão channel, situated in the northern region of Pará, provides a compelling illustration of these phenomena. Over the period from 1945 to 2014, estuarine morphodynamic processes have resulted in the displacement and abandonment of a meander within the main channel. This preliminary investigation delineates these changes across three temporal phases: i) 1945-1990, characterized by heightened sinuosity; ii) 1990-2005, marked by the expansion of point bars; and iii) 2005-2014, characterized by the emergence of a cut bank. The primary objective of this study is to illustrate these processes and their consequential morphological alterations.
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Sullivan, Raymond, Morgan D. Sullivan, Patrick Dedmon e Stephen Edwards. "Occurrence and mining of coal and sand deposits in the Middle Eocene Domengine Formation of the Mount Diablo Coalfield, California". In Regional Geology of Mount Diablo, California: Its Tectonic Evolution on the North America Plate Boundary. Geological Society of America, 2021. http://dx.doi.org/10.1130/2021.1217(04).
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ABSTRACT Mount Diablo Coalfield was the largest producer of coal in California from the 1860s to 1906. The now-depleted coalfield is located on the northeast limb of the Mount Diablo anticline. The mineable coal seams occur in the Middle Eocene Domengine Formation, which is predominantly composed of quartz-rich sandstone with several thin coal seams. As many as 26 mine operations were established to mine the coal, and it has been estimated that the total production exceeded 4 million tons. The coal fueled the industrial growth of the major cities of northern California. The mines closed at the turn of the nineteenth century as competition from better coals from Washington Territory and overseas entered the market. After coal mining was abandoned, sand operations were established in the early and mid-twentieth century to mine the silica-rich sandstone. The extraction methods used for sand were underground room-and-pillar mining and surface open-pit mining. The high-quality sand was used widely in the production of pottery and glass, and in foundries. Previous studies have interpreted the environment of deposition of these quartz-rich sandstone and coal deposits as barrier island with tidal channels or delta, tidal shelf, and marsh complexes along a north-south–trending shoreline. However, the excellent exposures in the sand mines display abundant evidence for their deposition in a fluvial/estuarine system. Their regional distribution indicates that they were deposited in a northeast-southwest–trending incised-valley system formed by fluvial incision during a lowstand. The incised valley was filled with fluvial and estuarine deposits made up of quartz-rich sand brought in by streams that flowed westward from the Sierra Nevada.
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Carling, P., e R. Breakspear. "Gravel dunes and antidunes in fluvial systems". In River, Coastal and Estuarine Morphodynamics: RCEM 2007, Two Volume Set, 1015–20. CRC Press, 2007. http://dx.doi.org/10.1201/noe0415453639-c128.
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Bianchi, Thomas S. "Sources and Distribution of Sediments". In Biogeochemistry of Estuaries. Oxford University Press, 2006. http://dx.doi.org/10.1093/oso/9780195160826.003.0014.
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The uplift of rocks above sea level on the Earth’s surface over geological time, produces rock material that can be altered into soils and sediments by weathering processes. Over geological time, a fraction of sediments can be sequestered for storage in the ocean basins—with most of it stored in the coastal margin. However, much of this material is modified via processing in large river estuarine systems which can ultimately affect the long-term fate of these terrigenous materials. Sediments produced from weathering of igneous, metamorphic, and sedimentary rocks are principally transported to the oceans through river systems of the world. The major routes of sediment transport from land to the open ocean can simply be illustrated through the following sequence: streams, rivers, estuaries, shallow coastal waters, canyons, and the abyssal ocean. It should be noted that significant and long-term storage occurs in river valleys and floodplains (Meade, 1996). Submarine canyons are also thought to be temporary storage sites for land-derived sediments; however, episodic events such as turbidity currents and mud slides can move these sediments from canyons to the abyssal ocean (more details on coastal margin transport to the deep ocean are provided in chapter 16). The annual sediment flux from rivers to the global ocean is estimated to range from 18 to 24 × 109 metric tonnes (Milliman and Syvitski, 1992). Conversely, estuaries will eventually fill-in with fluvial inputs of sediments over time, and ultimately reach an equilibrium whereby export and import of sediment supply are balanced (Meade, 1969). For example, recent studies have shown that sediment accumulation in the Hudson River estuary, both short (Olsen et al., 1978) and long term (Peteet and Wong, 2000), is in equilibrium with sea level rise. More specifically, it is believed that river flow controls the direction of sediment flux in the Hudson, while variations in spring-neap tidal amplitude control the magnitude (Geyer et al., 2001). Weathering is typically separated into two categories: physical and chemical. Physical weathering involves the fragmentation of parent rock materials and minerals through processes such as freezing, thawing, heating, cooling, and bioturbation (e.g., endolithic algae, fungi, plant roots, and earthworms).
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DeMaster, David J., e Robert C. Aller. "Biogeochemical Processes on the Amazon Shelf: Changes in Dissolved and Paniculate Fluxes During River/Ocean Mixing". In The Biogeochemistry of the Amazon Basin. Oxford University Press, 2001. http://dx.doi.org/10.1093/oso/9780195114317.003.0020.
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The immense discharge of the Amazon River causes river/ocean mixing to take place out on the continental shelf instead of within a drowned river valley, as in many smaller dispersal systems (Nittrouer and DeMaster, 1996). The magnitude of this discharge can be appreciated by recognizing that the Amazon River supplies approximately 20% (6 x 1015 L yr−1) of the freshwater reaching the oceans via fluvial transport and roughly 6% (1.2 x 1015 g yr−1, Meade et al. 1985) of the global riverine sediment discharge. Chemical, physical, and biological processes occurring in the river/ocean mixing zone control the fates of these riverine materials, as well as the fates of substances brought onto the shelf from offshore as a result of the estuarine-like circulation. Depending on balances between transport, reaction rates, and sedimentation, the mixing zone may act as a net source, sink, or bypass conduit for chemical species in the coastal environment. For example, if Amazon River nutrients such as silicate, phosphate, or nitrate are simply removed from solution and buried as particulate biogenic debris on the adjacent shelf, the river would have little influence on global ocean nutrient budgets. In contrast, if nutrients coming down the river are not efficiently buried nearshore (as a result of minimal biological uptake or efficient recycling), then they may contribute to larger scale oceanic or atmospheric budgets of Si, P, and N (Treguer et al. 1995; Delaney, 1998). The Amazon River transports ~1015 moles yr−1 of particulate organic carbon from the terrestrial environment to the ocean (Degens et al. 1991). The fate of this material (some of it from leaf litter and some of it from older, more refractory soils) is important to understand because the Amazon River/ocean mixing zone comprises a significant fraction of all deltaic depositional environments, where ~50% of the marine burial of organic matter occurs (Berner 1982, 1989, Hedges and Keil 1995; Devol et al. this volume). The Amazon River also discharges an equivalent amount of dissolved organic carbon (~1012 moles yr−1), much of which is in the form of high molecular weight organic compounds (Sholkovitz et al. 1978, Degens et al. 1991).
Trabalhos de conferências sobre o assunto "Fluvial-estuarine systems"
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Hasiotis*, Stephen T., Mark Reilly, Ian Moffat e Simon C. Lang. "The Neoichnology of the Modern Fluvial and Estuarine Sediments in Moreton Bay, Queensland, Australia: Relationships of Terrestrial, Freshwater and Marine Organisms to Physicochemical Characters of Sedimentary Systems". In International Conference and Exhibition, Melbourne, Australia 13-16 September 2015. Society of Exploration Geophysicists and American Association of Petroleum Geologists, 2015. http://dx.doi.org/10.1190/ice2015-2211572.
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Pichach, Craig, Marco Melo Llanos e Mazda Irani. "New Topics on Inflow Control Devices Application: Longer Wells and Solvent-SAGD". In SPE Thermal Well Integrity and Production Symposium. SPE, 2024. https://doi.org/10.2118/223071-ms.
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Summary In recent years, operators have increasingly turned to drilling longer wells as a means of reducing total well pairs. However, effective control measures, such as the utilization of Inflow Control Devices (ICDs) for producers and steam splitters for injectors, are imperative to prevent poor conformance. Following the successful completion of the SAGD Demonstration in Sawn Lake in 2018, plans are underway to drill additional wells informed by the insights gained from the pilot project. The objective is to further extend well lengths to streamline costs and boost production rates, thereby achieving quicker cost payback periods. Nevertheless, the primary challenge lies in enhancing conformance while maximizing recovery. This paper addresses this challenge by exploring strategies to optimize conformance and maintain peak recovery rates amidst the deployment of longer wells in the SAGD process. The heterogeneity of Athabasca McMurray oil sands reservoirs is a consequence of complex estuarine and fluvial depositional environments. This complexity is further compounded by hydrocarbon biodegradation, presenting challenges to reservoir characteristics. Notably, reservoir heterogeneity significantly influences SAGD recovery outcomes. In response, the introduction of inflow control devices (ICDs) has emerged as a strategy to enhance SAGD performance. These devices serve to establish a more uniform steam chamber, thereby reducing steam consumption, improving steam sweep efficiency, and enhancing oil production efficiency. However, challenges persist in optimizing steam delivery efficiencies within the SAGD process, including addressing steam conformance along the production/injection lateral due to reservoir heterogeneities, optimizing steam trap controls, and ensuring appropriate completion sizing to accommodate wellbore hydraulics. In response to the industry trend of drilling longer wells to optimize costs and enhance production rates, the implementation of Inflow Control Devices (ICDs) and steam splitters has become crucial for achieving effective reservoir conformance. Drawing from the successful SAGD Demonstration in Sawn Lake in 2018, where wells were drilled longer to expedite production and reduce costs, this paper addresses the challenge of improving conformance while maximizing recovery. The inherent heterogeneity of Athabasca McMurray oil sands reservoirs, compounded by hydrocarbon biodegradation, poses significant challenges to SAGD performance. To mitigate these challenges, this study introduces the use of ICDs to create a more uniform steam chamber, thereby reducing steam consumption, enhancing sweep efficiency, and optimizing oil production. Key factors affecting steam delivery efficiencies, such as reservoir heterogeneity, steam trap controls, and completion sizing, are examined within the context of the SAGD process. Utilizing reservoir modeling techniques, this paper evaluates the impact of reservoir heterogeneity on producer performance, comparing scenarios with and without ICDs. Emphasis is placed on the design considerations for ICD wells, particularly focusing on choking and resistance parameters. Through comparative analysis of ICD systems with varying resistance profiles, this study underscores the importance of selecting ICDs with lower resistance before flashing and higher resistance after flashing, particularly for longer wells, to optimize performance and enhance recovery.