Download or read book Structure Dynamics and Mixing Processes in a Buoyant River Plume Entering a Fjord written by Rebecca Adam McPherson and published by . This book was released on 2018 with total page 164 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Impacts of Lateral Spreading and Upstream Conditions on Buoyant River Plumes written by Yeping Yuan and published by . This book was released on 2012 with total page 144 pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation investigates the nature of physical processes associated with buoyant river plumes under the impacts of rotation, lateral spreading and upstream conditions. Two sets of laboratory experiments, one focused on the whole rotating buoyant plume, and the other zoomed into the near field plume, are studied. When lighter fluid is released into denser water, buoyancy causes the lighter intruding flow to run on top of the ambient water. This baroclinic flow propagates both in the offshore direction due to strong momentum from the inflow source and laterally in the alongshore direction because of the horizontal pressure gradient. This energetic region is the so-called near-field region where the plume behaves like a buoyant jet and is characterized by high momentum and strong stratification. Under the influence of the Coriolis force, the density driven flow is then guided along the coast, forming an anti-cyclonic bulge (in northern hemisphere). In this large scale region, called far-field region, the flow is more geophysical and less energetic. The transition between the two regions is the mid-field region in which the fluid transfers from an energetic flow into a geophysical current. The first laboratory experiment is designed to simulate the dynamics of two adjacent coastal river plumes in a rotating reference frame. The plumes are generated on a rotating table using two identical fresh water inlets, with blue and red dye indicating upstream and downstream river flows, respectively. We successfully calculate the depth field for the combined two-plume system and differentiate between the two plumes using a two-dimensional calibration map. With the upstream coastal current acting as the ambient condition, the downstream plume bulge does not reach a steady condition. The downstream bulge is pulled into the upstream bulge, forming a larger re-circulating bulge which then becomes unstable. The coastal current transport can be calculated by assuming a geostrophic cross-balance balance with an empirical coefficient & alpha = 0.6. The impact of lateral spreading on mixing was investigated for laboratory scale non-rotating stratified-shear plumes. The experiment is begun with the release of a vertical wall of freshwater and the simultaneous activation of a pump which supplies freshwater to the filling basin. Velocity and density fields are obtained using the combined particle image velocimetry (PIV) and planar laser induced fluorescence (PLIF) method, while the lateral spreading rate is determined using the optical thickness method (OTM). The vertical mixing is parameterized by the turbulent buoyancy flux, which is calculated using a control volume approach. Both the lateral spreading rate and mixing are related to inflow Fr, where the lateral spreading rate decreases with Fri while mixing increases with Fri. By comparing the mixing in the laterally confined and unconfined cases, we observe that although the lateral spreading significantly modifies the plume vertical structure, it does not change the local turbulent buoyancy flux. On the other hand, the lateral spreading increases the horizontal area over which mixing occurs and as a result it increases the net dilution of river water at a fixed distance from the river mouth. Unlike the local mixing process, we observe that the plume structure is significantly different in the laterally confined and unconfined plumes. Hypothesize is that the laterally spreading river plume might be a source of non-linear internal solitary waves with trapped cores. Such waves are commonly observed in fjords, straits and coastal ocean, where a strong shear-stratified flow meets dramatical topography changes. A series of small scale Kelvin-Helmholtz instability billows are generated along the edge of the large-scale waves, propagating downstream and finally breaking at the wave trough. This phenomenon highly increases the mixing and entrainment at the edge and trailing edges of the wave while it inhibits the mixing at the frontal side of the wave.

Download or read book River Plumes and Estuaries written by Alexander Osadchiev and published by Frontiers Media SA. This book was released on 2022-09-01 with total page 289 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Dynamics and Numerical Modeling of River Plumes in Lakes written by Navid Nekouee and published by . This book was released on 2010 with total page 185 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Models of the fate and transport of river plumes and the bacteria they carry into lakes are developed. They are needed to enable informed decisions about beach closures to avoid economic losses, and to help design water intakes and operate combined sewer overflow schemes to obviate exposure of the public to potential pathogens. This study advances our understanding of river plumes dynamics in coastal waters by means of field studies and numerical techniques. Extensive field measurements were carried out in the swimming seasons of 2006 and 2007 on the Grand River plume as it enters Lake Michigan. They included simultaneous aerial photography, measurements of lake physical properties, the addition of artificial tracers to track the plume, and bacterial sampling. Our observed results show more flow classes than included in previous studies (e.g. CORMIX). Onshore wind can have a significant effect on the plume and whether it impacts the shoreline. A new classification scheme based on the relative magnitude of plume-crossflow length scale and Richardson number based on the wind speed is devised. Previous studies on lateral spreading are complemented with a new relationship in the near field. The plume thickness decreased rapidly with distance from the river mouth and a new non-dimensional relationship to predict thickness is developed. Empirical near field models for surface buoyant plumes are reviewed and a near field trajectory and dilution model for large aspect ratio surface discharge channels is devised. Bacterial reductions due to dilution were generally small (less than 10:1) up to 4.5 km from the river mouth. E. coli decay rates were significantly affected by solar radiation and ranged from 0.2 to 2.2 day-1 which were within the range of previous studies in Lake Michigan. Total coliform survived longer than E. coli suggesting different die-off mechanisms. Mathematical models of the bacterial transport are developed that employ a nested modeling scheme to represent the 3D hydrodynamic processes of surface river discharges in the Great Lakes. A particle tracking model is used that provides the capability to track a decaying tracer and better quantify mixing due to turbulent diffusion. Particle tracking models have considerable advantages over gradient diffusion models in simulating bacterial behavior nearshore that results in an improved representation of bacteria diffusion, decay and transport. Due to the complexity and wide variation of the time and length scale of the hydrodynamic and turbulent processes in the near field (where plume mixing is dominated by initial momentum and buoyancy) and far field (where plume mixing is dominated by ambient turbulence), a coupling technique is adapted. The far field random walk particle tracking model incorporates the empirical near field model. It simulates the transport, diffusion and decay of bacteria as discrete particles and employs the near field output as the source and transports the particles based on ambient currents predicted by the 3D hydrodynamic model. The coupled model improves dilution predictions in the near field. The new techniques advance our knowledge of the nearshore fate and transport of bacteria in the Great Lakes and can be ultimately applied to the NOAA Great Lakes Coastal Forecasting System to provide a reliable prediction tool for bacterial transport in recreational waters."--Summary.

Download or read book Using Lagragian Surface Drifters to Study Wind Forcing and Lateral Spreading in a Buoyant River Plume written by Georgia Kakoulaki and published by . This book was released on 2015 with total page 232 pages. Available in PDF, EPUB and Kindle. Book excerpt: River plume entering the coastal ocean under sufficiently high discharge make a transition from an offshore-directed buoyant jet that is characterized by intense mixing and rapid lateral spreading, to an alongshore coastal current of relatively constant width and minimal mixing with ambient waters. The main goal of this dissertation is to identify and understand the mechanisms that transform the Merrimack River from an energetic jet (near-field plume) to a passive coastal current (far-field plume) and how the environmental factors like river discharge, tides and wind affect evolution of the plume. Data from were collected during twelve days of experiments in 2009-2012, with river discharge ranging between 150-800 m3sˉ1, using a fleet of 27 surface Lagrangian drifters (approximately 350 individual deployments). The drifters were released in the vicinity of the Merrimack River plume lift-off region, in three groups of nine, representing early-, mid-, and late-ebb time periods. The role of wind in river plumes has been of interest to many scientists but previous studies have focused primarily on the plume far-field. In this study we focus on wind impacts in the near and mid-field. The data indicate that the plume is unresponsive to wind forcing less than 4 msˉ1. In contrast, when wind speed exceeds 4 msˉ1 the plume is affected even in the near field. The stronger wind influence was influenced in the mid-field (4-12km) which is the region where the energetic plume transitions toward a passive far-field coastal current with Coriolis force growing in relative strength. The instantaneous wind influence weakens beyond approximately 12km yielding to longer time-scale Ekman processes. The tradition from a confined estuary to an unconfined coastal ocean introduces lateral spreading, which occurs preferentially near the surface and results in a flow that spreads laterally as it propagates forward in the direction of mean flow. During this transition, the plume undergoes vertical and lateral adjustments primarily due to mixing. A normalized plume width, based on the standard deviation of cross streamline drifter positions, was calculated for each group of drifters to examine changes in the local plume spreading rate as the plume evolved. Initial rapid expansion of the plume was observed to persist in all cases until an spreading is abruptly arrested anywhere from 1 to 8 km from the river mouth. The length and time scales associated with this shutdown of spreading are investigated in the context of key environmental forcing parameters, and scaling relationship are hypothesized. Our results showed a dependence pf the plume expansion on the initial environmental parameters and with the initial wave speed cin (at the point of release), to be linearly related with the temporal (Ts) and spacial scales (Ls). An along track Froude number was estimated by using the along drifter distance and the plume expansion in time and space. The temporal and spacial scales agreed with the maximum values of the along track Froude number. If the along track Froude number is equal to one, width expansion is twice as large as forward distance. On the other hand, for Froude number values of two , the width expansion and forward distance should be equal. Moreover, taking into consideration the calculations of the maximum seaward expansion an idealized advective plume using only inflow plume properties by Yankovsky and Chapman (1997), it was shown that the plume will laterally spread up to a distance of one Rossby radius and after that the Coriolis force will arrest spreading.

Download or read book Wind and Wave influenced Mixing and Dynamics in the Fraser River Plume written by Samuel Kastner and published by . This book was released on 2018 with total page 53 pages. Available in PDF, EPUB and Kindle. Book excerpt: Rivers play a large role in the transport of matter between ecosystems by connecting interior regions with lakes and oceans. River outflows, or plumes, constitute a significant delivery mechanism of pollutants, sediment, and nutrients to the coastal environment. Such plumes are common along the worlds coastlines, but are poorly understood and difficult to sample due to their complexity. The effects of external forcing (such as winds and waves) on river plumes is particularly understudied, but has been shown to play a role in the behavior of the plume. The Fraser River (the site of proposed and existing oil infrastructure) is a key system to understand, as its mouth is near both a major population center (Vancouver, BC) and unique coastal ecosystems. This study presents observations of plume mixing and stream-normal momentum balances in the Fraser river plume using Lagrangian surface drifters. The Strait of Georgia commonly experiences calm to moderate winds from the Southeast and strong storm winds from the Northwest in the winter, and there are differences in plume behavior between these conditions. Under SE winds, the plume thins, spreads, and turns to the right (North) upon exiting the river mouth, mixing intensely for a short period of time. This process is dominated by a balance between stream-normal pressure gradient, Coriolis, and rotational acceleration, as previous studies have shown. Under NW winds, the plume stays thicker, narrower, and flows directly across the Strait while forming a lateral front on its northern side, mixing at a slower rate for longer. Different momentum terms dominate under this wind condition: the stream- normal balance pits Coriolis and rotational acceleration pressure gradient against interfacial shear stress, wind stress, wave radiation stress gradient, and ambient current body force. The two configurations of the plume show that variable winds can have a substantial impact on the shape of the plume, which can lead to changes in the sea surface anomaly associated with the dome of freshwater exiting the river mouth. Additionally, while spreading causes the plume to mix intensely under SE winds, the net mixing under NW winds is larger due to the longer extent of the plume. This indicates that large spreading is not always necessary for substantial plume mixing. Understanding the conditions that change plume mixing and behavior is a critical step in describing the pathways of pollutants, sediment, and nutrients as they enter the coastal ecosystem through a river plume.

Download or read book The Dynamics of Buoyant Rotational River Plumes written by Alexander R. Horner-Devine and published by . This book was released on 2003 with total page 384 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Physical Processes in Near Field Buoyant Plumes Turbulence Mixing and Lateral Spreading written by Fei Chen and published by . This book was released on 2009 with total page 286 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Critical Zones written by Bruno Latour and published by MIT Press. This book was released on 2020-10-13 with total page 473 pages. Available in PDF, EPUB and Kindle. Book excerpt: Artists and writers portray the disorientation of a world facing climate change. This monumental volume, drawn from a 2020 exhibition at the ZKM Center for Art and Media, portrays the disorientation of life in world facing climate change. It traces this disorientation to the disconnection between two different definitions of the land on which modernizing humans live: the sovereign nation from which they derive their rights, and another one, hidden, from which they gain their wealth—the land they live on, and the land they live from. Charting the land they will inhabit, they find not a globe, not the iconic “blue marble,” but a series of critical zones—patchy, heterogenous, discontinuous. With short pieces, longer essays, and more than 500 illustrations, the contributors explore the new landscape on which it may be possible for humans to land—what it means to be “on Earth,” whether the critical zone, the Gaia, or the terrestrial. They consider geopolitical conflicts and tools redesigned for the new “geopolitics of life forms.” The “thought exhibition” described in this book can opens a fictional space to explore the new climate regime; the rest of the story is unknown. Contributors include Dipesh Chakrabarty, Pierre Charbonnier, Emanuele Coccia, Vinciane Despret, Jerôme Gaillarde, Donna Haraway, Joseph Leo Koerner, Timothy Lenton, Richard Powers, Simon Schaffer, Isabelle Stengers, Bronislaw Szerszynski, Jan A. Zalasiewicz, Siegfried Zielinski Copublished with ZKM | Center for Art and Media Karlsruhe

Download or read book Encyclopedia of Lakes and Reservoirs written by Lars Bengtsson and published by Springer. This book was released on 2012-06-25 with total page 954 pages. Available in PDF, EPUB and Kindle. Book excerpt: Lakes and reservoirs hold about 90% of the world's surface fresh water, but overuse, water withdrawal and pollution of these bodies puts some one billion people at risk. The Encyclopedia of Lakes and Reservoirs reviews the physical, chemical and ecological characteristics of lakes and reservoirs, and describes their uses and environmental state trends in different parts of the world. Superbly illustrated throughout, it includes some 200 entries in a range of topics, including acidification, artificialisation, canals, climate change effects, dams, dew ponds, drainage, eutrofication, evaporation, fisheries, hydro-electric power, nutrients, organic pollution, paleolimnology, reservoir capacities and depths, sedimentation, water resources and more.

Download or read book Fjord Oceanography written by Howard Freeland and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 691 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fjords are deep, glacia11y carved estuaries that are pecu1iar to certain coast1ines, and have severa1 characteristics that dist inguish them from sha110wer embayments. At higher latitudes they indent the western coast1ines of Scandinavia, North and South America, and New Zea1and. They are a1so a common feature of much of the arctic coast1ine. The papers contained in this vo1ume were presented at a workshop funded by the NATO Advanced Studies Institute in Victoria, British Co1umbia. It may seem curious to the reader that this specia1 c1ass of estuaries shou1d have attracted an international gathering of oceanographers from severa1 different discip1ines. The reas on for this interest stems from both practica1 and scientific considerations. On the one hand, fjords are a feature common to the coast1ines of severa1 countries that depend heavi1y on the oceans for communication, fisheries and other resources. The impact of man's activities on these coasts has created a demand for new know1edge of the physica1, bio10gica1 and chemica1 aspects of fjords. Sometimes man's inf1uence on the ocean is intentiona1 as, for examp1e, in the artificia1 contro1 of ice cover; often it is the more insidious bui1d-up of toxic wastes that is of concern. These prob1ems are particu1ar1y acute where the conf1icting demands of fisheries, industria1 deve10pment and re creation meet in a sing1e fjord; and indeed, this is a common occurence a10ng severa1 of the fjords in Scandinavia and Canada.

Download or read book Physical Processes in Lakes and Oceans written by Jorg Imberger and published by American Geophysical Union. This book was released on 1998 with total page 678 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Turbulent Jets and Plumes written by Joseph Hun-wei Lee and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 391 pages. Available in PDF, EPUB and Kindle. Book excerpt: Jets and plumes are shear flows produced by momentum and buoyancy forces. Examples include smokestack emissions, fires and volcano eruptions, deep sea vents, thermals, sewage discharges, thermal effluents from power stations, and ocean dumping of sludge. Knowledge of turbulent mixing by jets and plumes is important for environmental control, impact and risk assessment. Turbulent Jets and Plumes introduces the fundamental concepts and develops a Lagrangian approach to model these shear flows. This theme persists throughout the text, starting from simple cases and building towards the practically important case of a turbulent buoyant jet in a density-stratified crossflow. Basic ideas are illustrated by ample use of flow visualization using the laser-induced fluorescence technique. The text includes many illustrative worked examples, comparisons of model predictions with laboratory and field data, and classroom tested problems. An interactive PC-based virtual-reality modelling software (VISJET) is also provided. Engineering and science students, researchers and practitioners may use the book both as an introduction to the subject and as a reference in hydraulics and environmental fluid mechanics.

Download or read book Real time Coastal Observing Systems for Marine Ecosystem Dynamics and Harmful Algal Blooms written by Babin, Marcel and published by UNESCO. This book was released on 2008-06-05 with total page 880 pages. Available in PDF, EPUB and Kindle. Book excerpt: The proliferation of harmful phytoplankton in marine ecosystems can cause massive fish kills, contaminate seafood with toxins, impact local and regional economies and dramatically affect ecological balance. Real-time observations are essential for effective short-term operational forecasting, but observation and modelling systems are still being developed. This volume provides guidance for developing real-time and near real-time sensing systems for observing and predicting plankton dynamics, including harmful algal blooms, in coastal waters. The underlying theory is explained and current trends in research and monitoring are discussed.Topics covered include: coastal ecosystems and dynamics of harmful algal blooms; theory and practical applications of in situ and remotely sensed optical detection of microalgal distributions and composition; theory and practical applications of in situ biological and chemical sensors for targeted species and toxin detection; integrated observing systems and platforms for detection; diagnostic and predictive modelling of ecosystems and harmful algal blooms, including data assimilation techniques; observational needs for the public and government; and future directions for research and operations.

Download or read book Physical Oceanography of the Baltic Sea written by Matti Leppäranta and published by Springer Science & Business Media. This book was released on 2009-03-20 with total page 423 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Baltic Sea oceanographic research community is wide and the research history is over 100 years old. Nevertheless, there is still no single, coherent book on the physical oceanography of the Baltic Sea as a whole. There is a strong need for such a book, coming from working oceanographers as well as the university teaching programmes in advanced undergraduate to graduate levels. In the regional conference series in physical oceanography (Baltic Sea Science Conference, Baltic Sea Oceanographers' conference, Baltex-conferences) about 500 scientists take part regularly. Even more scientists work in the fields of marine biology, chemistry and the environment, and they need information on the physics of the Baltic Sea as well. There are nine countries bordering on the Baltic Sea and five more in the runoff area. The Baltic Sea as a source of fish, means of transportation and leisure activities is highly important to the regional society. In the runoff area there are a total of 85 million people. Research and protection strategies need to be developed, as the Baltic Sea is probably the most polluted sea in the world. Since the Baltic Sea has become an inner sea of the EU (apart from small shore parts of Russia in Petersburg and Kaliningrad), it is anticipated that the importance of the region will consequently rise. The book will arouse interest among students, scientists and decision makers involved with the Baltic problems. It will also give important background information for those working with biogeochemical processes in the Baltic Sea, because the physical forcing for those processes is of vital importance.

Download or read book Managing Wastewater in Coastal Urban Areas written by National Research Council and published by National Academies Press. This book was released on 1993-02-01 with total page 497 pages. Available in PDF, EPUB and Kindle. Book excerpt: Close to one-half of all Americans live in coastal counties. The resulting flood of wastewater, stormwater, and pollutants discharged into coastal waters is a major concern. This book offers a well-delineated approach to integrated coastal management beginning with wastewater and stormwater control. The committee presents an overview of current management practices and problems. The core of the volume is a detailed model for integrated coastal management, offering basic principles and methods, a direction for moving from general concerns to day-to-day activities, specific steps from goal setting through monitoring performance, and a base of scientific and technical information. Success stories from the Chesapeake and Santa Monica bays are included. The volume discusses potential barriers to integrated coastal management and how they may be overcome and suggests steps for introducing this concept into current programs and legislation. This practical volume will be important to anyone concerned about management of coastal waters: policymakers, resource and municipal managers, environmental professionals, concerned community groups, and researchers, as well as faculty and students in environmental studies.

Download or read book 2002 Ocean Sciences Meeting written by and published by . This book was released on 2002 with total page 422 pages. Available in PDF, EPUB and Kindle. Book excerpt: