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  • 1
    UID:
    gbv_1756575185
    Format: 292 Seiten , Illustrationen, Diagramme, Karten , 25 cm
    Series Statement: Schriftenreihe / Thüringer Landesamt für Umwelt, Bergbau und Naturschutz 120
    Note: "Herausgeber: Thüringer Landesanstalt für Umwelt, Bergbau und Naturschutz [...] Jena" (Impressum, Seite [2]) , "Autoren: Antje Becker, Mathias Deutsch, Manfred Fink, Björn Fischer, Ralf Haupt, Steffi Knoblauch, René Kühne, Markus Möller, Annett Peters, Kai Pfannschmidt, Tobias Reeh, Nico Trauth, Winfried Willems" (Rückseite des hinteren Banddeckels) , Gesamttitel auch: "Schriftenreihe des Thüringer Landesamtes für Umwelt, Bergbau und Naturschutz, Nr. 120" (Impressum, Seite [2]) , Literaturverzeichnis Seite 261-272
    Language: German
    Subjects: Geography , General works
    RVK:
    RVK:
    RVK:
    Keywords: Thüringen ; Fließgewässer ; Niedrigwasser ; Trockenheit ; Thüringen ; Talsperre ; Fluss ; Dürre ; Abfluss ; Niederschlag ; Thüringen ; Abflussregime ; Datenanalyse ; Wasserhaushalt ; Wasserwirtschaft
    Author information: Fink, Manfred 1969-
    Author information: Pfannschmidt, Kai 1965-
    Author information: Deutsch, Mathias 1965-
    Author information: Reeh, Tobias 1975-
    Library Location Call Number Volume/Issue/Year Availability
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  • 2
    UID:
    gbv_845986651
    Format: xv, 103 Seiten , Illustrationen
    Content: Stream water and groundwater are important fresh water resources but their water quality is deteriorated by harmful solutes introduced by human activities. The interface between stream water and the subsurface water is an important zone for retention, transformation and attenuation of these solutes. Streambed structures enhance these processes by increased water and solute exchange across this interface, denoted as hyporheic exchange. This thesis investigates the influence of hydrological and morphological factors on hyporheic water and solute exchange as well as redox-reactions in fluvial streambed structures on the intermediate scale (10–30m). For this purpose, a three-dimensional numerical modeling approach for coupling stream water flow with porous media flow is used. Multiple steady state stream water flow scenarios over different generic pool-riffle morphologies and a natural in-stream gravel bar are simulated by a computational fluid dynamics code that provides the hydraulic head distribution at the streambed. These heads are subsequently used as the top boundary condition of a reactive transport groundwater model of the subsurface beneath the streambed. Ambient groundwater that naturally interacts with the stream water is considered in scenarios of different magnitudes of downwelling stream water (losing case) and upwelling groundwater (gaining case). Also, the neutral case, where stream stage and groundwater levels are balanced is considered. Transport of oxygen, nitrate and dissolved organic carbon and their reaction by aerobic respiration and denitrification are modeled. The results show that stream stage and discharge primarily induce hyporheic exchange flux and solute transport with implications for specific residence times and reactions at both the fully and partially submerged structures. Gaining and losing conditions significantly diminish the extent of the hyporheic zone, the water exchange flux, and shorten residence times for both the fully and partially submerged structures. With increasing magnitude of gaining or losing conditions, these metrics exponentially decrease. Stream water solutes are transported mainly advectively into the hyporheic zone and hence their influx corresponds directly to the infiltrating water flux. Aerobic respiration takes place in the shallow streambed sediments, coinciding to large parts with the extent of the hyporheic exchange flow. Denitrification occurs mainly as a “reactive fringe” surrounding the aerobic zone, where oxygen concentration is low and still a sufficient amount of stream water carbon source is available. The solute consumption rates and the efficiency of the aerobic and anaerobic reactions depend primarily on the available reactive areas and the residence times, which are both controlled by the interplay between hydraulic head distribution at the streambed and the gradients between stream stage and ambient groundwater. Highest solute consumption rates can be expected under neutral conditions, where highest solute flux, longest residence times and largest extent of the hyporheic exchange occur. The results of this thesis show that streambed structures on the intermediate scale have a significant potential to contribute to a net solute turnover that can support a healthy status of the aquatic ecosystem.
    Note: kumulative Dissertation , Dissertation Mathematisch-Naturwissenschaftliche Fakultät der Universität Potsdam 2015
    Additional Edition: Erscheint auch als Online-Ausgabe Trauth, Nico Flow and reactive transport modeling at the stream-groundwater interface
    Language: English
    Keywords: Flussbett ; Flusswasser ; Grundwasser ; Grundwasserstrom ; Stoffübertragung ; Modellierung ; Oberflächengewässer ; Grundwasserleiter ; Hydraulik ; Hydrogeologie ; Flussinsel ; Numerisches Modell ; Hochschulschrift
    Library Location Call Number Volume/Issue/Year Availability
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  • 3
    UID:
    gbv_856996343
    Format: 1 Online-Ressource (xv, 103 Seiten) , Illustrationen, Diagramme
    Content: Stream water and groundwater are important fresh water resources but their water quality is deteriorated by harmful solutes introduced by human activities. The interface between stream water and the subsurface water is an important zone for retention, transformation and attenuation of these solutes. Streambed structures enhance these processes by increased water and solute exchange across this interface, denoted as hyporheic exchange. This thesis investigates the influence of hydrological and morphological factors on hyporheic water and solute exchange as well as redox-reactions in fluvial streambed structures on the intermediate scale (10–30m). For this purpose, a three-dimensional numerical modeling approach for coupling stream water flow with porous media flow is used. Multiple steady state stream water flow scenarios over different generic pool-riffle morphologies and a natural in-stream gravel bar are simulated by a computational fluid dynamics code that provides the hydraulic head distribution at the streambed. These heads are subsequently used as the top boundary condition of a reactive transport groundwater model of the subsurface beneath the streambed. Ambient groundwater that naturally interacts with the stream water is considered in scenarios of different magnitudes of downwelling stream water (losing case) and upwelling groundwater (gaining case). Also, the neutral case, where stream stage and groundwater levels are balanced is considered. Transport of oxygen, nitrate and dissolved organic carbon and their reaction by aerobic respiration and denitrification are modeled. The results show that stream stage and discharge primarily induce hyporheic exchange flux and solute transport with implications for specific residence times and reactions at both the fully and partially submerged structures. Gaining and losing conditions significantly diminish the extent of the hyporheic zone, the water exchange flux, and shorten residence times for both the fully and partially submerged structures. With increasing magnitude of gaining or losing conditions, these metrics exponentially decrease. Stream water solutes are transported mainly advectively into the hyporheic zone and hence their influx corresponds directly to the infiltrating water flux. Aerobic respiration takes place in the shallow streambed sediments, coinciding to large parts with the extent of the hyporheic exchange flow. Denitrification occurs mainly as a “reactive fringe” surrounding the aerobic zone, where oxygen concentration is low and still a sufficient amount of stream water carbon source is available. The solute consumption rates and the efficiency of the aerobic and anaerobic reactions depend primarily on the available reactive areas and the residence times, which are both controlled by the interplay between hydraulic head distribution at the streambed and the gradients between stream stage and ambient groundwater. Highest solute consumption rates can be expected under neutral conditions, where highest solute flux, longest residence times and largest extent of the hyporheic exchange occur. The results of this thesis show that streambed structures on the intermediate scale have a significant potential to contribute to a net solute turnover that can support a healthy status of the aquatic ecosystem.
    Note: kumulative Dissertation , Dissertation Universität Potsdam 2015
    Additional Edition: Erscheint auch als Druck-Ausgabe Trauth, Nico Flow and reactive transport modeling at the stream-groundwater interface
    Additional Edition: Erscheint auch als Druck-Ausgabe Trauth, Nico Flow and reactive transport modeling at the stream-groundwater interface 2015
    Language: English
    Keywords: Flussbett ; Flusswasser ; Grundwasser ; Grundwasserstrom ; Stoffübertragung ; Modellierung ; Oberflächengewässer ; Grundwasserleiter ; Hydraulik ; Hydrogeologie ; Flussinsel ; Numerisches Modell ; Hochschulschrift
    URL: Volltext  (kostenfrei)
    URL: Volltext  (kostenfrei)
    Library Location Call Number Volume/Issue/Year Availability
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