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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Aquatic sciences 62 (2000), S. 105-124 
    ISSN: 1420-9055
    Keywords: Key words: Numerical modeling, hydrodynamics, lake.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract: A numerical model of the hydrodynamic and thermal structure of an artificial lake was designed and developed as a basis for an ecological water-quality model. It allows the quantification of the vertical mixing processes that govern not only the thermal structure but also the nutrient exchanges, and more generally the distribution of dissolved and particulate matter between the different parts of the lake. The vertical temperature profiles were calculated by solving the one-dimensional heat transfer equation that takes into account the internal heat sources and sinks, advection due to inflow and outflow and the molecular and eddy diffusions. A finite-difference discretization of first-order in time and second-order in space was chosen. The numerical time-step was three hours and layers were one-meter in thickness. These time- and space-scales are well-suited to perform a precise simulation of the different processes occurring over a seasonal period. Moreover, this simulation requires only a reasonable amount of computer time.¶This model was used to study an artificial lake, (i.e. a reservoir), located in the high Loire valley (Roanne, France). To precisely identify the physical processes followed with an accurate numerical modeling, on-site data were acquired intensively over three years. Temperatures were monitored hourly at 11 different levels in the three main reaches of the reservoir to study the lake hydrodynamics and thermal behaviour. Meterological measurements were made every 20 minutes. One-year data were used for calibration, whereas the model was validated using the data collected over the other two years.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1573-5117
    Keywords: Seine river ; ecological modelling ; validation ; anthropic impacts
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The Seine river crosses the most densely populated and industrialized area of France, Paris (16 million inhabitants), surrounded by fertile land with intensive agriculture. In the framework of a CNRS (Scientific Research National Center) research project, computer programs have been designed to tackle problems related to eutrophication, non-point pollution and the impact of sewage during dry or wet periods (urban runof and sewage network overflow). The PROSE software has been specially designed to simulate the behaviour of the most disturbed stretches of the Seine ecosystem on the last 300 kilometers of the river, upstream of the estuarine area. The 1-D hydraulic sub-model of PROSE is based on a finite difference solution of Saint-Venant equations solved with the Preissman scheme. It simulates steady state situations as well as highly transient situations such as fast changes in river discharge during rainy periods or dam motions. The biological sub-model is based on the RIVE model, describing the major processes in a river ecosystem: primary production, heterotrophic bacterial activity and organic matter decomposition, major nutrients species (nitrogen, phosphorus), nitrifying activity and oxygen balance. Water column and sediment variables are simulated. Most of the parameters have been estimated during laboratory experiments or field studies. Different situations observed between 1989 and 1991 allowed a detailed validation of the model. The model was then used to explore the reaction of the ecosystem (particularly its oxygen status) to changes in physical constrains (discharge, reoxygenation at dams) or in biological processes (release of microorganisms accompanying waste water discharge).
    Type of Medium: Electronic Resource
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  • 3
    Publication Date: 2019-07-17
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
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  • 4
    Publication Date: 2019-07-17
    Description: Data pertaining to environmental conditions, sympagic (sea ice) microalgal dynamics and particle flux were collected before the spring ice break-up 2001 in Pierre Lejay Bay, adjacent to the Dumont d'Urville Station, Petrel Island, East Antarctica. An array of two multiple sediment traps and a current meter was deployed for five weeks, from 8 November to 6 December 2001. The sea-ice chlorophyll a and particulate organic carbon (POC) averaged 0.6 mg l−1 (30 mg m−2) and 20 mg l−1 (1 g m−2) near the coast. The POC export flux that reached a maximum of 79 mg m−2 d−1 during the study period was high compared to the one for the Weddell Sea. The flux was homogeneous from the surface to 47 m depth and increased sharply 33 days before the effective ice break-up. A north-western progressive vector of currents (i.e., Lagrangian drift) in the sub-ice surface waters was demonstrated. Bottom ice, platelet ice and under-ice water at 5 m were characterized by differences in colonization and short-term succession of microalgae.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
    Format: application/pdf
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