1,721,043 research outputs found
Characterization of Gatun Lake's Hydrodynamic Behaviour and Water Quality
No full textGatun Lake, located in the Panama Canal Watershed (PCW), is the main source of freshwater for the Canal's operations and it provides drinking water for nearly 600,000 people, which represents roughly 15% of the country's population. Since its creation at the beginning of the 20th century, Gatun Lake has slowly been transitioning from a swamp environment to a more saline-governed ecosystem. However, since the completion of the Canal's expansion project and inauguration of the Neo-Panamax locks in 2016, salinity in the lake has been increasing at a faster pace. The progressive salinization of this water body is not only a concern from the perspective of drinking water supply and human health, but for the lake's biodiversity as well. In order to understand the magnitude of this issue, evaluate the impact of climate change and design effective mitigation and management strategies, robust modelling tools are required. Nevertheless, these tools often require high volumes of high-quality data that are not always readily available. This paper illustrates the characterization of Gatun Lake's hydrodynamic behaviour and water quality condition using a numerical model built with Delft3D and publicly available open data, which includes bathymetry from GEBCO and hydrodynamic data from ACP's AQUARIUS web portal. Although further refinement of the model is still required, overall, it was demonstrated that reasonably good results can be obtained through a model built using publicly available open data.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Water Resource
Salt Intrusion Around the World Under Influence of Climate Change
No full textWe investigate the changes in surface water salinity intrusion lengths for estuaries around the world under influence of climate change. To do this, we make use of information from global data sets on present river geometry and present and predicted future river discharges, mean sea levels and tidal ranges, which we combine with various models for salt intrusion lengths. The used predictions are based on the RCP8.5 climate scenario and we use 2050 as time horizon, with the 10-percentile lowest discharge as representative value used as input in the intrusion length calculations. The salt intrusion models are two parametric descriptions and a semi-analytical model. With this, we calculate absolute and relative changes in salt intrusion length for a selection of estuaries around the world, to eventually scale up the analysis and develop a global map of changes in salt intrusion around the world under influence of climate change. The results so far indicate that many estuaries may be expected to experience a relative increase of salt intrusion length of over 10%. We also investigate which of the changing forcings most strongly affects the intrusion lengths and what type of estuary is most sensitive to changes. For most systems, the changes in river discharge characteristics are the most influential change, exceeding the influence of sea level rise. This study highlights the importance of studying the effect of climate change on estuarine salt intrusion in more detail, both in global analyses as in system specific detailed studies.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Environmental Fluid MechanicsMathematical PhysicsCoastal Engineerin
Data set from a bedload tracer field study in an alpine section of the Drava River in 2017 and 2018
No full textThis is a data set from a bedload tracer field study in an alpine section of the Drava River. It contains the characteristics and changing positions of transported bedload tracers, the grain sizes of the river bed surface and a time series of the bed shear stress. A number of 65 artificial bedload tracers were equipped with active very high frequency radio transmitters imitating 5 natural grains representative of five grain size classes. The tracers were all seeded on 11 May 2017 in a cross-section across five points in the middle of the river, 2.5 m apart laterally. Seeding was done from a boat in bags that contained the tracers and could be opened after they were lowered onto the riverbed. After seeding, 10 searches by boat up to 11 June 2018 resulted in total distances of up to more than 30 km. Grain size distributions of the riverbed surface were determined by Wolman Pebble Counts at 9 different locations in wadeable waters at low flow. The time series of bed shear stress was calculated for the seeding site and obtained from water depths modelled with a one-dimensional hydrodynamic-numerical model and a channel slope obtained from the analysis of cross-sections. The shear stress can also be calculated for cross-sections downstream of the seeding location by using the functions available in the corresponding publication. In the publication, this data set was used to derive a formula for the unsteady virtual velocity of the tracers, taking into account the deceleration due to mixing and advection. The description of bedload transport as a relay run in contrast to the individual runs of the decelerating tracers also made it possible to distinguish between the unsteady virtual velocity of bedload and the unsteady virtual velocity of decelerating bedload tracers
Positions of bedload tracers in an alpine section of the Drava River after seeding on 11 May 2017 up to 11 June 2018
No full textThis is a data set related to a bedload tracer field study in an alpine section of the Drava River between 11 May 2017 and 11 June 2018. It contains the positions of bedload tracers as obtained during 10 searches from a boat with antenna, receiver and GPS after the tracer seeding on 11 May 2017. A number of 65 artificial bedload tracers were deployed imitating 5 natural grains representative of five grain size classes. In addition, the recordings from a stationary antenna, located about 5 km downstream from the seeding location, are provided
Properties and seeding positions of bedload tracers in an alpine section of the Drava River on 11 May 2017
No full textThis is a data set related to a bedload tracer field study in an alpine section of the Drava River between 11 May 2017 and 11 June 2018. It contains the characteristics and seeding positions of bedload tracers. A number of 65 artificial bedload tracers were equipped with active very high frequency radio transmitters imitating 5 natural grains representative of five grain size classes. The tracers were all seeded on 11 May 2017 in a cross-section across five points in the middle of the Drava River, 2.5 m apart laterally. Seeding was done from a boat in bags that contained the tracers and could be opened after they were lowered onto the riverbed
Nematode fish parasites in the Danube River – Belgrade section.
No full textParasitic species of freshwater fishes represent a large group of organisms including either adults or larval stages. Macroparasites - Nematode (round worms) infect many different species of aquacultured and wild fish. Adult forms are typically found in fish digestive tract.
The present work covers the investigation of nematode parasites of fish from the Belgrade section of the Danube River. During ichthyoparasitological study have been collected and examined 22 freshwater fish species from families Cyprinidae (14), Esocidae (1), Percidae (4), Centrarchidae (1), Gadidae (1) and Siluridae (1). A total of 802 fish specimens have been examined and 54.86% were infected. In intestine of 12 infected fish species have been found 9 species of Nematode parasites - Hysterothylacium bidentatum (Linstow, 1899), Contracaecum siniperca (Dogiel & Achmerov, 1946), Contracaecum sp. juvenile (Railliet & Henry, 1912), Cammalanus lacustris (Zoega, 1776), Cammalanus truncatus (Rudolphi, 1814), Camallanus sp. juvenile (Railliet & Henry, 1915), Philometra rischta (Skrjabin, 1923), Rhabdochona denudata (Dujardin, 1845) and Rhabdochona hellichi (Šrámek, 1901). During investigation, species Philometra rischta has been marked off (“heat parasite”), infesting a four fish species (Blicca bjoerkna, Leuciscus idus, Perca fluviatilis, Sander lucioperca) with prevalence of infestation 1-17. Fish species with great number of nematode parasite in intestine was Lota lota (four), while other were infected with one or two parasites.Habersack H, editor. 4th International Conference on the Status and Future of the World’s Large Rivers;
2021 Aug 3-6; Moscow, Russia. 2021. p. 267
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Grain size distributions of the riverbed surface of an alpine section of the Drava River in 2018
No full textThis is a data set related to a bedload tracer field study in an alpine section of the Drava River between 11 May 2017 and 11 June 2018. It contains the grain size distributions of the riverbed surface at 9 locations in the Upper Drava River. In the related publication the median grain size of the riverbed surface near the seeding site served to obtain the relative grain sizes of the bedload tracers
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