Academic literature on the topic 'Freshwater plumes'
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Journal articles on the topic "Freshwater plumes"
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Osadchiev, Alexander, Igor Medvedev, Sergey Shchuka, Mikhail Kulikov, Eduard Spivak, Maria Pisareva, and Igor Semiletov. "Influence of estuarine tidal mixing on structure and spatial scales of large river plumes." Ocean Science 16, no. 4 (July 3, 2020): 781–98. http://dx.doi.org/10.5194/os-16-781-2020.
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Abstract. The Yenisei and Khatanga rivers are among the largest estuarine rivers that inflow to the Arctic Ocean. Discharge of the Yenisei River is 1 order of magnitude larger than that of the Khatanga River. However, spatial scales of buoyant plumes formed by freshwater runoff from the Yenisei and Khatanga gulfs are similar. This feature is caused by different tidal forcing in these estuaries, which have similar sizes, climate conditions, and geomorphology. The Khatanga discharge experiences strong tidal forcing that causes formation of a diluted bottom-advected plume in the Khatanga Gulf. This deep and weakly stratified plume has a small freshwater fraction and therefore occupies a large area on the shelf. The Yenisei Gulf, on the other hand, is a salt-wedge estuary that receives a large freshwater discharge and is less affected by tidal mixing due to low tidal velocities. As a result, the low-salinity and strongly stratified Yenisei plume has a large freshwater fraction and its horizontal size is relatively small. The results show that estuarine tidal mixing determines freshwater fraction in these river plumes, which governs their depth and area after they spread from estuaries to coastal sea. Therefore, the influence of estuarine mixing on spatial scales of a large river plume can be of the same importance as the roles of river discharge rate and wind forcing. In particular, plumes with similar areas can be formed by rivers with significantly different discharge rates, as illustrated by the Yenisei and Khatanga plumes.
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Kumar, R. K., H. W. Chiang, and F. Kalos. "Entrainment and Mixing in Vertical Buoyant Light-Gas Plumes." Journal of Energy Resources Technology 118, no. 1 (March 1, 1996): 77–81. http://dx.doi.org/10.1115/1.2792697.
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A simple model is developed to determine the entrainment coefficient and the spread of a light-gas plume in a quiescent atmosphere. Experiments performed with low-velocity saltwater/freshwater and helium-in-air jets indicate that buoyant gas plumes spread significantly faster than thermal plumes. The calculated effluent concentrations are in excellent agreement with those measured when an entrainment coefficient of 0.15 is used in the plume equations. This is significantly higher than the entrainment coefficients of 0.075 to 0.093 reported for thermal plumes.
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Liu, Wen-Cheng, Hong-Ming Liu, Chih-Chieh Young, and Wei-Che Huang. "The Influence of Freshwater Discharge and Wind Forcing on the Dispersal of River Plumes Using a Three-Dimensional Circulation Model." Water 14, no. 3 (January 29, 2022): 429. http://dx.doi.org/10.3390/w14030429.
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Tidal estuaries provide crucial pathways for contaminant transport. The salinity levels in estuaries and coasts are conserved substances that function as natural tracers to easily understand the offshore transport of substances that are subject to environmental factors. A three-dimensional (3D) circulation and mass transport model were utilized to delineate the salinity plume in a tidal estuary and continental shelf. The numerical modeling results were compared with the tidal amplitudes and phases, velocities, and salinities at different gauging stations in 2017. Quantitatively, the simulation and measurement results are in reasonably good agreement. Furthermore, the validated model was adopted to estimate the recovery times in tidal estuaries that are subjected to extreme freshwater discharges that come from the upstream reaches during typhoon events and to analyze the influences of freshwater discharge and wind stress on the river plume around the continental shelf. The simulated results revealed that the salinity recovery time at the river mouth due to Typhoon Saola in 2012 was less than 8 days. Increased inputs from freshwater discharge resulted in changes in the distances and areas of the river plumes. Linear regression relationships between the plume distance/plume area and the total freshwater discharge inputs were established. Neap and high slack tides were associated with the maximum plume distances and areas. Excluding tidal forcing resulted in larger plume distances and areas compared to the case in which tidal forcing was considered. The southward-favorable and northward-favorable plumes were controlled by northeasterly winds and southwesterly winds, respectively. The relative importance of freshwater discharges and wind forcing was explored. The results indicate that freshwater discharges frequently dominated the river plume, except when strong southwesterly or northeasterly winds prevailed.
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Kimura, Satoshi, Paul R. Holland, Adrian Jenkins, and Matthew Piggott. "The Effect of Meltwater Plumes on the Melting of a Vertical Glacier Face." Journal of Physical Oceanography 44, no. 12 (November 26, 2014): 3099–117. http://dx.doi.org/10.1175/jpo-d-13-0219.1.
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Abstract Freshwater produced by the surface melting of ice sheets is commonly discharged into ocean fjords from the bottom of deep fjord-terminating glaciers. The discharge of the freshwater forms upwelling plumes in front of the glacier calving face. This study simulates the meltwater plumes emanated into an unstratified environment using a nonhydrostatic ocean model with an unstructured mesh and subgrid-scale mixing calibrated by comparison to established plume theory. The presence of an ice face reduces the entrainment of seawater into the meltwater plumes, so the plumes remain attached to the ice front, in contrast to previous simple models. Ice melting increases with height above the discharge, also in contrast to some simple models, and the authors speculate that this “overcutting” may contribute to the tendency of icebergs to topple inwards toward the ice face upon calving. The overall melt rate is found to increase with discharge flux only up to a critical value, which depends on the channel size. The melt rate is not a simple function of the subglacial discharge flux, as assumed by many previous studies. For a given discharge flux, the geometry of the plume source also significantly affects the melting, with higher melt rates obtained for a thinner, wider source. In a wider channel, two plumes are emanated near the source and these plumes eventually coalesce. Such merged meltwater plumes ascend faster and increase the maximum melt rate near the center of the channel. The melt rate per unit discharge decreases as the subglacial system becomes more channelized.
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De Andrés, Eva, Donald A. Slater, Fiamma Straneo, Jaime Otero, Sarah Das, and Francisco Navarro. "Surface emergence of glacial plumes determined by fjord stratification." Cryosphere 14, no. 6 (June 18, 2020): 1951–69. http://dx.doi.org/10.5194/tc-14-1951-2020.
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Abstract. Meltwater and sediment-laden plumes at tidewater glaciers, resulting from the localized subglacial discharge of surface melt, influence submarine melting of the glacier and the delivery of nutrients to the fjord's surface waters. It is usually assumed that increased subglacial discharge will promote the surfacing of these plumes. Here, at a western Greenland tidewater glacier, we investigate the counterintuitive observation of a non-surfacing plume in July 2012 (a year of record surface melting) compared to the surfacing of the plume in July 2013 (an average melt year). We combine oceanographic observations, subglacial discharge estimates and an idealized plume model to explain the observed plumes' behavior and evaluate the relative impact of fjord stratification and subglacial discharge on plume dynamics. We find that increased fjord stratification prevented the plume from surfacing in 2012, show that the fjord was more stratified in 2012 due to increased freshwater content and speculate that this arose from an accumulation of ice sheet surface meltwater in the fjord in this record melt year. By developing theoretical scalings, we show that fjord stratification in general exerts a dominant control on plume vertical extent (and thus surface expression), so that studies using plume surface expression as a means of diagnosing variability in glacial processes should account for possible changes in stratification. We introduce the idea that, despite projections of increased surface melting over Greenland, the appearance of plumes at the fjord surface could in the future become less common if the increased freshwater acts to stratify fjords around the Greenland ice sheet. We discuss the implications of our findings for nutrient fluxes, trapping of atmospheric CO2 and the properties of water exported from Greenland's fjords.
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Pimenta, Felipe M., A. D. Kirwan, and Pablo Huq. "On the Transport of Buoyant Coastal Plumes." Journal of Physical Oceanography 41, no. 3 (March 1, 2011): 620–40. http://dx.doi.org/10.1175/2010jpo4473.1.
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Abstract The role of discharge conditions and shelf geometry on the transport of coastal plumes is studied with a fully nonlinear, primitive equation hydrodynamic model. The physical setting is an estuarine channel with a small discharge Rossby number. By simulating different discharge magnitudes, buoyant plumes are shown to be succinctly described by a simple coastal front model. Three results emerge from the model analysis. First, the plume transport is given by T = γ0(g′ph2/2f ), where γ0 is a parameter dependent on the ratio of the front and the plume widths, g′p is the plume reduced gravity, h is the plume maximum depth, and f is the Coriolis parameter. Second, this model links the plume transport directly to upstream river conditions with T = γQr, where Qr is the river outflow and γ is a parameter that relates to entrainment, the geometry of the plume front and shelf slope, and the fraction of freshwater carried downshelf. Third, these equations reduce to analytic results previously established for special cases, providing useful formulas to estimate the plume transport from hydrographic and river discharge observations.
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Hudson, B., I. Overeem, D. McGrath, J. P. M. Syvitski, A. Mikkelsen, and B. Hasholt. "MODIS observed increase in duration and spatial extent of sediment plumes in Greenland fjords." Cryosphere 8, no. 4 (July 4, 2014): 1161–76. http://dx.doi.org/10.5194/tc-8-1161-2014.
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Abstract. The freshwater flux from the Greenland Ice Sheet (GrIS) to the North Atlantic Ocean carries extensive but poorly documented volumes of sediment. We develop a suspended sediment concentration (SSC) retrieval algorithm using a large Greenland specific in situ data set. This algorithm is applied to all cloud-free NASA Moderate Resolution Imaging Spectrometer (MODIS) Terra images from 2000 to 2012 to monitor SSC dynamics at six river plumes in three fjords in southwest Greenland. Melt-season mean plume SSC increased at all but one site, although these trends were primarily not statistically significant. Zones of sediment concentration > 50 mg L−1 expanded in three river plumes, with potential consequences for biological productivity. The high SSC cores of sediment plumes ( > 250 mg L−1 expanded in one-third of study locations. At a regional scale, higher volumes of runoff were associated with higher melt-season mean plume SSC values, but this relationship did not hold for individual rivers. High spatial variability between proximal plumes highlights the complex processes operating in Greenland's glacio–fluvial–fjord systems.
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Marta-Almeida, Martinho, Anna Dalbosco, David Franco, and Manuel Ruiz-Villarreal. "Dynamics of river plumes in the South Brazilian Bight and South Brazil." Ocean Dynamics 71, no. 1 (November 11, 2020): 59–80. http://dx.doi.org/10.1007/s10236-020-01397-x.
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AbstractThe plumes from the rivers of the South Brazilian Bight (SBB) and South Brazil (SB) were studied using a realistic model configuration. River plume variability on continental shelves is driven by the input of river runoff into the shelf, by wind variability, and also by ambient currents and its seasonal variability, especially the Brazil Current, which are realistically modelled in this study. It is presented a simulation of 4 years using a nested configuration, which allows resolving the region around Florianópolis with very high resolution (∼150 m). The dispersion of river plumes was assessed not only with the hydrodynamical model results but also by using passive tracers whose dynamics was analyzed seasonally. Several dyes were released together with the river discharges. This approach allowed calculating the depths of the riverine freshwater, and the resulting regions affected by the plumes. Northward intrusions of waters from the southern region, under the potential influence of the distant La Plata river plume, were evaluated with a Lagrangian approach. The local river plumes are confined to the inner shelf, except south of 30°S where discharges from Lagoa dos Patos disperse over the shelf in the spring and summer. The Brazil Current flowing southward over the slope prevents the river plumes from interaction with oceanic mesoscale dynamics. The river plumes are, thus, mainly controlled by the wind forcing. The plumes from SBB are able to disperse until SB following the southward wind regime typical of the summer. And both the SB and La Plata river plumes are also able to reach SBB, forced by the northward wind typical of the winter season, until the latitude of 25.5°S. A low salinity belt (below 35) is present along the coastal region of SB and SBB year-round, supported by contributions from both the large and small rivers. The interaction between the different plumes influences the dispersion patterns, shielding the Florianṕolis coastal region from plumes of distant rivers, and dispersing the plume of SBB rivers away from Santa Catarina Island as it disperses southward during the summer months.
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Rodrigues, Raphael Paiva, Bastiaan Adriaan Knoppers, Weber Friederichs Landim de Souza, and Elisamara Sabadini Santos. "Suspended matter and nutrient gradients of a small-scale river plume in Sepetiba Bay, SE-Brazil." Brazilian Archives of Biology and Technology 52, no. 2 (April 2009): 503–12. http://dx.doi.org/10.1590/s1516-89132009000200030.
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Coastal river plumes represent one of the final stages of material transport across the land-sea interface. Most studies, however have focused on the behavior of medium to large sized river plumes of coastal-shelf waters, whereas small sized river plumes acting within estuaries have been neglected. This study addressed the behavior of suspended particulate matter (SPM), dissolved inorganic nutrients (DIN, DIP and DSi) and Chlorophyll a (Chl. a) of a small sized river plume derived from the closely lain São Francisco and Guandú river channels, set in the Sepetiba Bay estuary, SE-Brazil. Two surface water sampling campaigns were conducted, one in January 2003 (humid summer conditions) and the other in June 2003 (dry winter conditions). On both occasions, the plumes dispersed in a SE direction towards the inner portion of the bay. The "wet" event plume was more turbid, nutrient rich and dispersed beyond nearshore waters, whereas the "dry" event plume proliferated as a narrow, less turbid and more nutrient poor film alongshore. Both exhibited a marked degree of patchiness, induced by the differential input of materials from the river sources and resuspension processes from the shallow nearshore bottom. The São Francisco river channel was the main source of freshwater, SPM and nutrients, except for ammonia (NH4+-N) derived from domestic effluents of the Guandú river. The mesohaline portion of the estuarine mixing zone of the plumes behaved as a slight source for SPM, DSi and DIP, due to bottom resuspension processes. N:P molar ratios ranged between 80:1 and 20:1 along the estuarine gradient, being higher in the summer than in the winter event, indicating that DIP was the potential nutrient limiting primary production. Chl. a concentrations increased at the outer premises of the plume, suggesting that the short residence times and turbidity of the plume waters, hampered primary production nearshore, particularly during the summer occasion. The small sized plume lacked the spatial decoupling between the estuarine mixing and turbidity zones, generally observed in larger sized coastal-shelf plumes.
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Matano, Ricardo P., and Elbio D. Palma. "The Spindown of Bottom-Trapped Plumes." Journal of Physical Oceanography 40, no. 7 (July 1, 2010): 1651–58. http://dx.doi.org/10.1175/2010jpo4352.1.
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Abstract This note considers the decay of a bottom-trapped freshwater plume after the causative freshwater inflow has ceased. It is shown that shortly after the low-density inflow stops, the barotropic pressure field that it created radiates away and the ocean circulation becomes controlled by baroclinic pressure gradients generated by the remnants of the inflow. This produces a reversal of the circulation in the region downstream of the inflow, after which the entire plume starts to move in the upstream direction. The decay of the plume is henceforth controlled by upstream oceanic flow and dilution through cross-isopycnal mixing.
Dissertations / Theses on the topic "Freshwater plumes"
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Fong, Derek Allen. "Dynamics of freshwater plumes: observations and numerical modeling of the wind-forced response and alongshore freshwater transport." Thesis, Massachusetts Institute of Technology, 1988. http://hdl.handle.net/1721.1/58510.
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Thesis (Ph. D.)--Joint Program in Physical Oceanography (Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences; and the Woods Hole Oceanographic Institution), 1988.Includes bibliographical references (leaves 163-172).
A freshwater plume often forms when a river or an estuary discharges water onto the continental shelf. Freshwater plumes are ubiquitous features of the coastal ocean and usually leave a striking signature in the coastal hydrography. The present study combines both hydrographic data and idealized numerical simulations to examine how ambient currents and winds influence the transport and mixing of plume waters. The first portion of the thesis considers the alongshore transport of freshwater using idealized numerical simulations. In the absence of any ambient current, the downstream coastal current only carries a fraction of the discharged fresh water; the remaining fraction recirculates in a continually growing "bulge" of fresh water in the vicinity of the river mouth. The fraction of fresh water transported in the coastal current is dependent on the source conditions at the river mouth. The presence of an ambient current augments the transport in the plume so that its freshwater transport matches the freshwater source. For any ambient current in the same direction as the geostrophic coastal current, the plume will evolve to a steady-state width. A key result is that an external forcing agent is required in order for the entire freshwater volume discharged by a river to be transported as a coastal current. The next section of the thesis addresses the wind-induced advection of a river plume, using hydrographic data collected in the western Gulf of Maine. The observations suggest that the plume's cross-shore structure varies markedly as a function of fluctuations in alongshore wind forcing. Consistent with Ekman dynamics, upwelling favorable winds spread the plume offshore, at times widening it to over 50 km in offshore extent, while downwelling favorable winds narrow the plume width to a few Rossby radii. Near-surface current meters show significant correlations between cross-shore currents and alongshore wind stress, consistent with Ekman theory. Estimates of the terms in the alongshore momentum equation calculated from moored current meter arrays also indicate an approximate Ekman balance within the plume. A significant correlation between alongshore currents and alongshore wind stress suggests that interfacial drag may be important. The final section of the thesis is an investigation of the advection and mixing of a surface-trapped river plume in the presence of an upwelling favorable wind stress, using a three-dimensional model in a simple, rectangular domain. Model simulations demonstrate that the plume thins and is advected offshore by the cross shore Ekman transport. The thinned plume is susceptible to significant mixing due to the vertically sheared horizontal currents. The first order plume response is explained by Ekman dynamics and a Richardson number mixing criterion.
by Derek Allen Fong.
Ph.D.
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Edwards, David D. "Real Exposure: Field Measurement of Chemical Plumes in Headwater Streams." Bowling Green State University / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1401289267.
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Houndegnonto, Odilon Joël. "Analyse des variations thermohalines des échelles intrasaisonnière à saisonnière des panaches d'eau douce du Golfe de Guinée." Thesis, Brest, 2021. http://www.theses.fr/2021BRES0105.
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Dans le Golfe de Guinée (GG), les masses d’eau douce provenant des décharges des fleuves et les taux de précipitations élevés contribuent à la stratification en densité de la couche superficielle océanique, et jouent un rôle clé dans la modulation des interactions air-mer. Cependant, les variations thermohalines des couches superficielles au sein des panaches d’eau douce du GG sont encore mal connues, car très peu observées et documentées. L’objectif principal de cette thèse est donc d’étudier et de documenter la variabilité spatiale à mésoéchelle horizontale (10-100 km) et verticale (0-100m), intra-saisonnière à saisonnière de la structure 3D thermohaline dans les panaches d’eau douce du GG, et notamment les panaches des fleuves Congo et Niger. Tout d’abord, à l’aide des données d’observations satellite SSS SMOS, notre étude a montré que les panaches d’eau douce dans cette région s’étendent vers l’océan du large suivant deux régimes de propagation. Durant la période de septembre à janvier, ils se propagent vers le large en direction Nord-Ouest tandis que de janvier à avril, ils se redirigent vers le Sud-Ouest, où leur extension maximale est observée en avril. Le reste de l’année, de mai à août, est marqué par un épisode de salinisation de surface, où les panaches d’eau douce se dissipent avec une extension minimale observée en août. L’analyse du bilan de salinité dans la couche mélangée de surface a permis de mettre en évidence les principaux processus physiques contrôlant la variabilité saisonnière de la salinité au sein de ces panaches d’eau douce. Ce diagnostic a montré que les processus d’advection horizontale et les flux d’eau douce associés aux précipitations et aux décharges des fleuves expliquent principalement de la distribution offshore des masses d’eau de faible salinité dans cette région. Dans le panache du Congo en particulier, l’advection horizontale de salinité est principalement expliquée par la dérive d’Ekman du vent de surface. Ensuite, nous avons montré que la distribution offshore du panache du Congo aux échelles intra-saisonnières est associée à des couches de barrière de sel d’une part, et à des profils verticaux de densité en marches d’escalier d’autre part. Dans une étude de cas (au 31/03/216), nous avons montré que la stratification thermohaline en marches d’escalier observée, résulterait de la dynamique de cisaillement entre le flux d’Ekman de surface associée à la distribution offshore (Nord-Ouest) du panache du Congo, et le flux géostrophique (Sud-Est) associé aux masses d’eau de subsurface de l’océan ouvert à l’Ouest, plus denses et plus salées. Enfin, à partir d’une approche lagrangienne, nous avons mis en évidence l’origine et la structuration à grande échelle des masses d’eau impliquées dans la forte stratification haline observée au large du Congo. Cette étude a montré le fort cisaillement des courants à l’oeuvre au niveau des gradients halins au sein de la colonne d’eau associée à ces profilsIn the Gulf of Guinea (GG), freshwater originated from river discharges and high precipitation rates contribute to the upper ocean density stratification, and play a key role in modulating air-sea interactions. However, the thermohaline variations of the ocean upper layers within the freshwater plumes in the GG are still poorly known, as they are poorly observed and documented. The main objective of this thesis is therefore to study and document the spatial variability at horizontal mesoscale (10-100 km) and vertical (0-100m), from intra-seasonal to seasonal time scales of the thermohaline 3D structure in the freshwater plume areas of the GG: mainly the Congo and Niger Rivers plumes. First, using SSS SMOS satellite data, our study showed that freshwater plumes in this region extend towards the open ocean following two propagation regimes. During September to January, they propagate northwestward while from January to April they redirect to the southwest, where their maximum extension is observed in April. The rest of the year, from May to August, is marked by a surface salinization episode, where the freshwater plumes dissipate with a minimum extension observed in August. A salinity budget analysis in the surface mixed layer allowed highlighting the main physical processes controlling the seasonal variability of salinity within these freshwater plumes. We showed that horizontal advection processes and freshwater fluxes by precipitation and river discharges are the main contributors of low SSS distribution in this region. In the southeastern Gulf of Guinea, off Congo, the horizontal SSS advection is dominated by Ekman wind-driven currents. Second, we showed that the offshore distribution of the Congo plume on intra-seasonal time scales is associated with salt barrier layers and with thermohaline staircases profiles. In a case study (for 2016/03/31), we showed that the observed thermohaline staircases would result from the shear dynamics between the surface Ekman flow associated with the offshore (North-Westward) distribution of the Congo plume, and the geostrophic (South-Eastward) flow associated with the denser and saltier subsurface water masses of the open ocean to the west. Finally, using a Lagrangian approach, we have highlighted the origin and large-scale structuring of water masses involved in the strong haline stratification observed off Congo. This study showed the strong shear of the currents associated with the vertical salinity gradients within the water column associated with the staircases profiles
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Castaneda, Rowshyra. "Factors affecting the distribution, abundance and condition of an invasive freshwater bivalve in a thermal plume." Thesis, McGill University, 2013. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=117072.
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The Asian clam, Corbicula fluminea, is a freshwater bivalve that has recently invaded artificially heated waters downstream of the Gentilly-2 nuclear power plant in the St. Lawrence River. C. fluminea is one of the world's most invasive molluscs, owing to its ability to rapidly establish dense populations in new areas. Its physiological requirements have apparently restricted its global distribution to waterbodies whose temperatures remain above 2ºC throughout the year; however, recent invasions suggest that the clam may be adapting to lower temperatures. Using published data, I have identified patterns of the distribution and population densities of C. fluminea in artificially heated and natural (non-heated) waterbodies. Densities of C. fluminea populations do not differ between artificially heated and non-heated waters, but exhibit a positive trend with latitudinal distance such that peak densities occur in middle latitudes. The occurrence of C. fluminea in United States rivers below 40oN is positively correlated with human population density. At local scales within the St. Lawrence River, temperature, flow velocity, turbidity and depth were identified as factors that affect the distribution and density of C. fluminea. Furthermore, the clam was restricted to sites within the thermal plume of the Gentilly-2 power plant, and its body condition and reproductive status varied in time and space. The presence of C. fluminea in St. Lawrence River raises the question of whether the species can use the thermal plume to adapt to colder conditions and spread further in the river, especially as warming trends continue.La petite corbeille d'Asie, Corbicula fluminea, est un bivalve subtropical d'eau douce qui a récemment envahi la panache thermique de la centrale nucléaire Gentilly-2 (CNG2) du fleuve Saint-Laurent. C. fluminea est un des mollusques les plus envahissant du monde, en raison de sa capacité rapide à former de nouvelle population dense. Ses besoins physiologiques semblent limiter sa distribution mondiale à des plans d'eau maintenant une temperature de plus de 2ºC au courant de l'année; néanmoins, des envahissements récents suggèrent que la palourde s'adapte à des températures plus basses. Utilisant des donnés publiés, j'ai identifié des types de distribution et de densité de C. fluminea dans des eaux chauffés artificiellement et non-chauffés. Les densités de C. fluminea ne diffèrent pas entre les deux types d'eau, mais démontrent une relation positive avec la distance latitudinal, où les densités maximales sont atteintes aux latitudes centrale. La présence de C. fluminea dans les rivières Américaines se situant au sud du 40ºN est positivement corrélée avec la densité de la population humaine. À l'échelle locale du fleuve Saint-Laurent, la température, le courant d'eau, la turbidité et la profondeur ont été identifiés comme facteurs affectant la distribution et la densité de C. fluminea. De plus, la palourde était limitée aux sites du panache thermique de la CNG2, et sa condition et son statut réproductif varient en temps et espace. La présence de C. fluminea dans le fleuve Saint-Laurent soulève des questions sur la possibilité de l'espèce d'utiliser la panache thermique afin de s'adapter à des conditions plus froides surtout si les tendances de réchauffement continuent.
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Ribeiro, Américo Soares. "Coupled modelling of the Tagus and Sado estuaries and their associated mesoscale patterns." Master's thesis, Universidade de Aveiro, 2015. http://hdl.handle.net/10773/15193.
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Mestrado em Ciências do Mar e das Zonas CosteirasGiven the close proximity between the Tagus and Sado estuaries, it is understandable that these two hydrodynamic systems have their discharges on the same coastal region. Several studies focus on the investigation of the complex circulation at the mouth of Tagus or Sado estuaries, however, the interaction between these two systems is not taken into account and there are no studies which contemplate the interaction between the two estuaries. With this objective, the three-dimensional model Delft3D-Flow was implemented in order to investigate the complex flows in Tagus and Sado estuaries and adjacent shelf. The numerical model was calibrated and validated using sea surface height, currents, salinity and water temperature data, and then applied to research the role of river discharge and wind effects under mesoscale currents and coastal dynamics at open ocean boundaries on the plumes interaction. The chosen period was the winter of 2009-2010. To examine the response of the estuarine plumes to different wind directions, five scenarios of moderate winds were considered blowing from each of the main four compass points, and with the absence of wind. Through the use of two distinct tracers, three different idealized scenarios were chosen: low, moderate and high Tagus and Sado river discharges. The results showed an evidence of estuarine plumes, filaments and mesoscale eddies caused by the interactions between the estuaries and the nearby coastal region. The obtained results also reveal a intrusion caused by the Sado plume in Tagus estuary after a 10-day simulation. This pattern was not observed for Tagus plume. It was also observed that the Sado estuarine water propagates to Tagus estuary in just 36 hours with coastal dynamics, when compared to the mesoscale currents forcing took around 120 hours. In summary, the model application developed in this study contributed to the characterization and understanding of the interaction between Tagus and Sado estuary’s, and in which conditions these occur.
Dada a proximidade entre os estuários do Tejo e do Sado, é reconhecido que as descargas destes estuários ocorrem na mesma região costeira. O conhecimento atual relativo à hidrodinâmica dos estuários do Tejo e do Sado resulta maioritariamente da exploração de resultados de modelos numéricos, que descrevem as propriedades físicas e padrões gerados pelas correntes de maré e descargas fluviais. Não obstante, verificou-se que a interação entre estes dois sistemas não é considerada, não havendo esforços no sentido de estudar os dois sistemas simultaneamente, bem como de descrever as relações que partilham e identificar as mútuas influências a nível dinâmico. Com este objetivo, foi implementado o modelo numérico tridimensional Delft3D-Flow, de forma a investigar a dinâmica do estuário do Tejo, do Sado e da região costeira adjacente. O modelo numérico foi calibrado e validado com a altura de maré, correntes, salinidade e temperatura da água, sendo aplicado para a investigação do efeito das descargas fluviais e do efeito do vento na interação das plumas destes estuários. O período escolhido para as simulações foi o Inverno de 2009-2010. Foram impostos dois tipos de forçamentos na fronteira aberta oceânica, um que comtempla as correntes de mesoescala e outro apenas a dinâmica costeira. Foram considerados cinco cenários para ventos moderados nos quatro principais quadrantes e para a ausência deste. Através do uso de dois traçadores distintos, foram escolhidos três cenários idealizados com descargas baixas, moderadas e altas dos rios Tejo e Sado. Os resultados evidenciaram a presença de plumas estuarinas, filamentos e eddies causados pela interação entre os estuários e a região costeira. Os resultados obtidos revelam ainda uma intrusão da pluma estuarina do Sado no estuário do Tejo após descargas fluviais significativas durante dez dias, contudo, este padrão não foi observado na pluma estuarina do Tejo. Foi ainda observado que a água estuarina do Sado se propaga para o estuário do Tejo em apenas 36 horas com apenas a dinâmica costeira, ao passo que com as correntes de mesoescala só se observou a intrusão após 120 horas. Sumariamente, o modelo desenvolvido para este estudo contribuiu para a caracterização e compreensão da interação entre os estuários do Tejo e Sado, e definição das condições em que esta ocorre.
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Ostrander, Christopher. "Physical factors controlling the temporal and spatial variability of freshwater plumes in Kaneohe Bay, Hawaiʻi." Thesis, 2007. http://hdl.handle.net/10125/20809.
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Han, Q., D. Chen, Yakun Guo, and W. Hu. "Saltwater-freshwater mixing fluctuation in shallow beach aquifers." 2018. http://hdl.handle.net/10454/15542.
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YesField measurements and numerical simulations demonstrate the existence of an upper saline plume in tidally dominated beaches. The effect of tides on the saltwater-freshwater mixing occurring at both the upper saline plume and lower salt wedge is well understood. However, it is poorly understood whether the tidal driven force acts equally on the mixing behaviours of above two regions and what factors control the mixing fluctuation features. In this study, variable-density, saturated-unsaturated, transient groundwater flow and solute transport numerical models are proposed and performed for saltwater-freshwater mixing subject to tidal forcing on a sloping beach. A range of tidal amplitude, fresh groundwater flux, hydraulic conductivity, beach slope and dispersivity anisotropy are simulated. Based on time sequential salinity data, the gross mixing features are quantified by computing the spatial moments in three different aspects, namely, the centre point, length and width, and the volume (or area in a two-dimensional case). Simulated salinity distribution varies significantly at saltwater-freshwater interfaces. Mixing characteristics of the upper saline plume greatly differ from those in the salt wedge for both the transient and quasi-steady state. The mixing of the upper saline plume largely inherits the fluctuation characteristics of the sea tide in both the transverse and longitudinal directions when the quasi-steady state is reached. On the other hand, the mixing in the salt wedge is relatively steady and shows little fluctuation. The normalized mixing width and length, mixing volume and the fluctuation amplitude of the mass centre in the upper saline plume are, in general, one-magnitude-order larger than those in the salt wedge region. In the longitudinal direction, tidal amplitude, fresh groundwater flux, hydraulic conductivity and beach slope are significant control factors of fluctuation amplitude. In the transverse direction, tidal amplitude and beach slope are the main control parameters. Very small dispersivity anisotropy (e.g., α_L⁄α_T <5) could greatly suppress mixing fluctuation in the longitudinal direction. This work underlines the close connection between the sea tides and the upper saline plume in the aspect of mixing, thereby enhancing understanding of the interplay between tidal oscillations and mixing mechanisms in tidally dominated sloping beach systems.
Shenzhen Key Laboratory for Coastal Ocean Dynamics and Environment (No. ZDSY20130402163735964), National High Technology Research & Development Program of China (No. 2012AA09A409).
Books on the topic "Freshwater plumes"
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Fong, Derek Allen. Dynamics of freshwater plumes: Observations and numerical modeling of the wind-forced response and alongshore freshwater transport. Woods Hole, Mass: Massachusetts Institute of Technology, Woods Hole Oceanographic Institution, Joint Program in Oceanography/Applied Ocean Science and Engineering, 1998.
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Mississippi River plume hydrography: Second annual report. New Orleans, La: U.S. Dept. of the Interior, Minerals Management Service, Gulf of Mexico OCS Region, 1996.
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P, Murray Stephen, Donley Jami, United States. Minerals Management Service. Gulf of Mexico OCS Region, and Louisiana State University (Baton Rouge, La.). Coastal Studies Institute, eds. Mississippi River plume hydrography: Second annual report. [New Orleans, La.]: U.S. Dept. of the Interior, Minerals Management Service, Gulf of Mexico OCS Region, 1996.
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Mosig, John. Australian Yabby Farmer. CSIRO Publishing, 1998. http://dx.doi.org/10.1071/9780643100749.
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This edition includes a chapter on water quality plus the latest findings in yabby farming. It provides a grounding in the basic principles of aquaculture and reflects the considerable advances in aquaculture technology over the last few years.
Here is the basic information on the yabby, its habitat, its health and nutrition requirements. The book covers pond management, production systems, equipment, harvesting, post-harvest handling, and marketing of the end product. It includes sections on the farming of those other freshwater crayfish, the redclaw and the marron, and contains a number of useful appendices.
Author John Mosig shares his experience of nearly 20 years, giving budding yabby farmers an insight into how they can run a yabby venture while developing their own aquaculture skills and gaining experience in fish husbandry. Practising crayfish farmers might find out how they too can do some things better.
Book chapters on the topic "Freshwater plumes"
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Garvine, Richard W. "The Role of Brackish Plumes in Open Shelf Waters." In The Role of Freshwater Outflow in Coastal Marine Ecosystems, 47–65. Berlin, Heidelberg: Springer Berlin Heidelberg, 1986. http://dx.doi.org/10.1007/978-3-642-70886-2_4.
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Archetti, Renata, and Maurizio Mancini. "Freshwater Dispersion Plume in the Sea: Dynamic Description and Case Study." In Hydrodynamics - Natural Water Bodies. InTech, 2012. http://dx.doi.org/10.5772/28390.
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Bean, Michael J. "Strategies for Biodiversity Protection." In Precious Heritage. Oxford University Press, 2000. http://dx.doi.org/10.1093/oso/9780195125191.003.0015.
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After a half century of ditching, diking, and draining the swamplands of southern Florida, a major effort to undo some of the ecological damage of those activities is now under way. In what is perhaps the largest ecological restoration effort of its kind anywhere, the federal and state governments are buying up large parcels of private land, changing dramatically the timing and quantity of freshwater flows to the huge “river of grass” that comprises the Florida Everglades, and even restoring the meanders and backwaters to the same Kissimmee River that an earlier generation of engineers “improved” by straightening and channelizing so as to eliminate its meanders and backwaters. Hundreds of millions of public dollars will be spent in this effort. If it succeeds, the steady degradation of one of the most biologically diverse and distinctive environments of the United States will be halted, and its recovery will have begun. The wood stork (Mycteria americana), snail kite (Rostrhamus sociabilis plumbeus), and Florida panther (Felis concolor coryi) are among the endangered species that this effort may ultimately benefit. Several hundred miles to the north, in the sandhills of North Carolina, a more modest but no less noteworthy conservation effort is under way. There, private owners of woodlots, horse farms, resorts, and even residential property are actively managing their longleaf pines to encourage the presence on their own land of another endangered species, the red-cockaded woodpecker (Picoides borealis). After a quarter century in which many private landowners came to fear the presence of endangered species on their land, sandhills landowners are now inviting them. The state and federal governments are spending few public dollars in this effort, and its scale is much smaller than that of the Everglades restoration. What drives the novel effort in North Carolina is a creative and flexible use of the provisions of the Endangered Species Act to encourage the sort of positive land stewardship that many landowners are willing to embrace. As the Florida and North Carolina examples illustrate, the challenge of effectively conserving the natural biological diversity of the nation requires the use of a flexible and diverse array of strategies.
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"Pacific Salmon: Ecology and Management of Western Alaska’s Populations." In Pacific Salmon: Ecology and Management of Western Alaska’s Populations, edited by Charles C. Krueger, Christian E. Zimmerman, and Joseph J. Spaeder. American Fisheries Society, 2009. http://dx.doi.org/10.47886/9781934874110.ch1.
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<em>Abstract.</em>—The Arctic-Yukon-Kuskokwim region encompasses over 40% of the State of Alaska. The region includes the watersheds of Norton Sound up to and including the village of Shishmaref, the Yukon River watershed within Alaska and Canada, and the Kuskokwim River watershed (including the coastal watersheds north of Cape Newenham), plus the Bering Sea and North Pacific Ocean marine ecosystems (see frontispiece map). Dramatic declines in salmon runs to the AYK region from 1997 to 2001 created havoc within the subsistence culture of rural Alaskan communities and left fishery managers and scientists puzzled over the causes for the declines, unsure of best management measures for the future. Since 2003, salmon stocks across the region have fluctuated widely. The Arctic-Yukon-Kuskokwim Sustainable Salmon Initiative (AYK SSI) is an innovative partnership between public and private institutions which provides a forum for regional organizations and state and federal agencies to cooperatively identify and address salmon research and restoration needs. The AYK SSI provided the means to interconnect state, federal, and Alaska Native organizations to collaboratively participate in the symposium, and to fund the symposium and this book. The symposium and this text seeks to describe the management of salmon fisheries in the AYK region, to communicate what is known and what needs to be known about ecological processes that cause change in salmon populations; and to discuss the effects on rural communities caused by variability in abundance of salmon. This book provides a single reference text for the region that serves as an access point to information that formerly resided in a variety of storage media—from file drawers to web sites to the primary literature—and one that links information across the freshwater and marine ecosystems of the region. Our hope is that the availability of this information would encourage future students, managers, and researchers to focus their interests on AYK salmon, and promote the long-term sustainability of Alaska’s salmon producing ecosystems.
Conference papers on the topic "Freshwater plumes"
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"River plumes of the Great Barrier Reef: freshwater, sediment and optical footprints quantified by the eReefs modelling system." In 22nd International Congress on Modelling and Simulation. Modelling and Simulation Society of Australia and New Zealand (MSSANZ), Inc., 2017. http://dx.doi.org/10.36334/modsim.2017.l22.bairn.
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Vogl, Anastasia, Nile Waldal, Parisa Sarmadi, Adam Fershtman, Rodrigo S. Mitishita, and Ian A. Frigaard. "Plug Cementing Stability." In ASME 2022 41st International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2022. http://dx.doi.org/10.1115/omae2022-79290.
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Abstract Off bottom plugs are set in both well drilling (kick-off plugs) and in well decommissioning (abandonment plugs). In both cases a dense fluid (cement slurry) is placed over less dense well-bore fluids. In the case of kick-off plugs, viscous pills are commonly used, which can help stabilize this mechanically unstable situation. Abandonment plugs however are often set on top of the freshwater that is used to clean the well prior to abandonment. This is the current practice for many wells in Northwestern Canada. It is a mystery how such cement plugs are able to stay in place for a time sufficient for the cement to thicken and hydrate, but field evidence suggests they do. In this paper we explore the mechanically unstable scenario of a heavy yield-stress fluid placed on top of a less dense Newtonian fluid in a cylindrical pipe, dimensionally scaled to represent an off-bottom plug. We present details of the experimental setup and its calibration. We then explore the buoyancy-driven exchange flows that occur in transitional parametric regimes between flow and no-flow states, by using both computer modelling and physical experimentation. 3D numerical simulation, using a Volume of fluid method, is carried out to capture the interface between the fluids. The 3D model provides us with a more detailed analysis of the concentration and velocity profiles, along with comparisons to snapshots of the experimental results. The aim is to explore the phenomenology of these unstable flows and be able to estimate timescales of the destabilization. Preliminary results are presented.
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Moghadam, A., and A. N. Corina. "Modelling Stress Evolution in Cement Plugs During Hydration." In 56th U.S. Rock Mechanics/Geomechanics Symposium. ARMA, 2022. http://dx.doi.org/10.56952/arma-2022-0966.
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ABSTRACT: In this work, we have developed a methodology to model the stress evolution in cement plugs during hydration. The model begins with the slurry state of cement and calculates the water consumption and void creation over time as the hydration reactions progress. The void volume change due to chemical shrinkage is imported into a coupled mechanical model that calculates the pore pressure drop and the resulting change in stresses. The results of the proposed modelling methodology are verified using lab experiments from the literature. The results provide new insights in understanding cement behavior under lab and field conditions. Under most scenarios, cement’s pore pressure drops to saturation pressure of water which leads to partial evaporation of the remaining pore water. This pore pressure drop controls the radial stress change, according to the theory of poroelasticity. For a plug set under an initial pressure of 5 MPa, the radial stress drops to 1.6 MPa after 20 hours of curing. This stress drop can cause the cement to debond from the casing, if the fluid pressure above the plug exceeds the final radial stress. This methodology can be extended to annular cements and initial cement stress after placement can be readily calculated. 1. INTRODUCTION Zonal isolation in active and abandoned wells is paramount to ensure minimal fugitive methane emissions and to protect shallow freshwater aquifers. Wells penetrate different strata and can create a leakage pathway in case of a damaged cement sheath. This has been linked to methane emissions to the atmosphere (Schout et al., 2019), and aquifers (Osborn et al., 2011). Historically, oil and gas wells have been the main culprit in providing the leakage pathway for unwanted fluids. As more geothermal, energy, and carbon storage wells are drilled as part of the energy transition, zonal isolation challenges require more attention due to the long expected lifetime for these wells and unique operating conditions.
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Abitalhah, M. Abiabhar, Nurul Nadia Ezzatty Abu Bakar, M. Aizat Haidi Hod, Avinash Kishore Kumar, Chee Hen Lau, and Myat Thuzar. "Abandonment of Wells Under the New Norm – Sacrificial Tubing Approach." In Offshore Technology Conference Asia. OTC, 2022. http://dx.doi.org/10.4043/31369-ms.
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Abstract This paper presents the success story of an exploration well in Malaysia evaluating the conventional approach of stacked cement plugs against the use of sacrificial tubing with a hydraulic disconnect sub system. Plug and Abandonment (P&A) is the process where the well is sealed permanently, and permanent well barrier must extend across the full cross section prior rig move. It is vital to ensure that plugged wells do not leak after abandonment, as there could be several potential leak paths or channeling from microannulus. Thus, well integrity shall be the utmost priority in designing the P&A strategy. Conventional P&A requires multiple cement plugs of a given length to be set and pressure tested, which could however be quite time-consuming and thus costly. The number of cement plugs will be based on the length of the open hole section, hydrocarbon zones presence or caprock to meet the P&A guidelines. The guidelines require that cement plugs be placed and tested across any open hydrocarbon-bearing formations, across all casing shoes, across freshwater aquifers, and perhaps several other areas near the surface. The thought process, design requirement both for the hardware and cement slurry, and execution follow through of a P&A approach with a sacrificial tubing method, driving for cost savings and operational efficiency will be elaborated. Some of the key points for replication based on lessons learnt are P&A with sacrificial tubing is economical justified for well scenario. As for the design, tubing centralizers or rotation is required in deviated hole for proper cement placement. Rotation of tubing during cementing is recommended for effective mud removal and cement placement for the case of no centralizer placement. This paper provides the novelty of the extensive planning, execution and improvement methods that will aid the project team to save cost and time in plug and abandonment (P&A) the well.