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  • Books  (6)
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  • Bremerhaven : Alfred-Wegener-Inst. für Polar- und Meeresforschung  (5)
  • Freiburg i. Br. : Inst. für Hydrologie der Univ.  (1)
  • Paris : IEA Publications
  • German  (6)
  • 2005-2009  (6)
  • GFZ Library  (6)
  • 1
    Series available for loan
    Series available for loan
    Freiburg i. Br. : Inst. für Hydrologie der Univ.
    Associated volumes
    Call number: ZS-065(26)
    In: Freiburger Schriften zur Hydrologie
    Description / Table of Contents: Knowledge about soil water transport and groundwater renewal rates is crucial for groundwater research and risk assessment. Particularly the impact of preferential flow paths in the unsaturated zone on pollutant transport is an important topic, as it affects the vulnerability of the adjacent aquifer. However, in literature the determination of preferential flow is only partly solved and especially quantification attempts have been rare. Therefore, a new method combining mathematical modelling with hydrological and environmental isotope data was developed to estimate the heterogeneity of the unsaturated transport processes. For this purpose, environmental isotope transport (18O, 2H) was investigated in several lysimeter experiments. A conceptual model was applied, which separates preferential and matrix flow. Both flow components are quantified and their transit time distribution functions are determined to construct specific vulnerability diagrams.Water flow and transport of environmental isotopes through the soil matrix was calculated using both a transient modelling approach solving numerically Richards and Convection-Dispersion-Equation for single porous medium and a lumped parameter approach using the Dispersion Model. The preferential flow component is assumed by piston flow occurring within one week and having no interaction with the soil matrix.For quantification a two component flow approach was applied to the isotope and hydrological data. The mean transit time distribution functions were obtained from the lumped parameter approach and visualized in specific vulnerability diagrams, showing when infiltrating water reaches the groundwater. This method was applied to different lysimeter experiments that were conducted under natural atmospheric conditions. Different lysimeters, filled mostly with sandy soil material, were under investigation to study the impact of soil properties and vegetation on the transport heterogeneity and amount of preferential flow.It was shown that the lumped parameter approach yielded good results modelling the isotope transport in the soils with bare surface. An application to the soils with vegetation required a modification of the classical input function including evapotranspiration and thus considering the infiltration events contributing to the discharge. Additional separation into the single vegetation periods improved the modelling.Preferential flow was observed in all soils and quantified with the two component flow approach. In bare sandy and gravel soils the mean fractions of preferential flow varied between 17 and 30 %. Here, the crucial parameter influencing these fractions was found to be the saturated hydraulic conductivity. In the cropped soils the mean fractions of preferential were dependent on the discharge rate and varied according to the vegetation. Mean fractions of 3 % and 18 % were observed in a loamy sand during intercrop period and cultivation of maize monoculture, respectively. The same soil material but cultivated with crop rotation yielded mean fractions of 14 % during maize, 4 % during winter barley and 15 % during the intercrop vegetation period. In a third experimental setup with sandy soil a mean fraction of 8 % was found.Specific vulnerability diagrams were constructed showing the mean transit time distribution functions of both, preferential and matrix flow. Their patterns were closely related to soil parameters. They can be used as a helpful tool to develop groundwater protection strategies more efficiently.It was shown that the presented method enabled the estimation of transport heterogeneity and the quantification of preferential flow under natural atmospheric conditions in bare and cropped lysimeters using environmental isotope data. Such isotopes are adequate tracer to study the transport processes in the unsaturated zone. It was revealed that experiments with continuous natural application like environmental tracers over long time periods were necessary to cover a broad range of flux variability and to determine transport heterogeneity.
    Type of Medium: Series available for loan
    Pages: VI, 111 S.
    Series Statement: Freiburger Schriften zur Hydrologie 26
    Classification:
    Hydrology
    Language: German
    Location: Lower compact magazine
    Branch Library: GFZ Library
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  • 2
    Series available for loan
    Series available for loan
    Bremerhaven : Alfred-Wegener-Inst. für Polar- und Meeresforschung
    Associated volumes
    Call number: ZSP-168-546 ; ZS-090(546)
    In: Berichte zur Polar- und Meeresforschung
    Type of Medium: Series available for loan
    Pages: 168 S. : graph. Darst.
    ISSN: 1618-3193
    Series Statement: Berichte zur Polar- und Meeresforschung 546
    Classification:
    Historical Geology
    Language: German
    Note: Zugl.: Bremen, Univ., Diss., 2006
    Location: AWI Reading room
    Location: Lower compact magazine
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  • 3
    Series available for loan
    Series available for loan
    Bremerhaven : Alfred-Wegener-Inst. für Polar- und Meeresforschung
    Associated volumes
    Call number: ZSP-168-545 ; ZS-090(545)
    In: Berichte zur Polar- und Meeresforschung
    Type of Medium: Series available for loan
    Pages: 185 S. : graph. Darst.
    ISSN: 1618-3193
    Series Statement: Berichte zur Polar- und Meeresforschung 545
    Language: German
    Note: Zugl.: Potsdam, Univ., Diss., 2006
    Location: AWI Reading room
    Location: Lower compact magazine
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  • 4
    Call number: ZSP-168-497 ; ZS-090(497)
    In: Berichte zur Polar- und Meeresforschung
    Description / Table of Contents: Analysen paläoklimatologischer Daten, z.B. basierend auf Eisbohrkernen, und meteorologischer Messungen haben gezeigt, dass in der Vergangenheit atmosphärische Klimaschwankungen mit verschiedenen zeitlichen Perioden von Jahrzehnten bis zu Jahrtausenden aufgetreten sind. Ursachen dieser Schwankungen sind sowohl Einflussfaktoren, die von außen auf die Atmosphäre wirken als auch atmosphäreninterne dynamische Prozesse. Diese dynamischen Prozesse können durch Multiskalenwechselwirkungen, d.h. durch Impuls- und Energieflüsse zwischen Strömungsmustern verschiedener räumlicher Ausdehnung, z.B. globaler langwelliger Atmosphärenschwingungen und kleinräumiger Hoch- und Tiefdruckgebiete, beschrieben werden. Zur Modellierung horizontaler atmosphärischer Multiskalenwechselwirkungen wurde in der vorgelegten Arbeit ein neues idealisiertes Atmosphärenmodell vorgestellt, das einen Beitrag zur verbesserten Beschreibung atmosphärischer Klimaschwankungen darstellt. Die Besonderheit des Einschichtenmodells besteht darin, dass die horizontale Auflösung der Atmosphäre zeitlich veränderlich und räumlich adaptiv ist. Damit können gleichzeitig in verschiedenen Regionen der Erde in Abhängigkeit vom aktuellen Strömungszustand unterschiedliche Auflösungen des Modells realisiert werden. Für bekannte stationäre und instationäre Lösungen der Modellgleichungen konnte anhand von Modellsimulationen nachgewiesen werden, dass das Modell korrekte Ergebnisse liefert. In einem weiteren Modellexperiment konnte als Beispiel für eine Multiskalenwechselwirkung die Auswirkung eines nicht realen einzeln stehenden Berges auf den troposphärischen Strahlstrom erfolgreich modelliert werden.
    Type of Medium: Series available for loan
    Pages: 129 S. , graph. Darst.
    ISSN: 1618-3193
    Series Statement: Berichte zur Polar- und Meeresforschung 497
    Classification:
    Meteorology and Climatology
    Language: German
    Location: AWI Reading room
    Location: Lower compact magazine
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  • 5
    Call number: ZSP-168-498 ; ZS-090(498)
    In: Berichte zur Polar- und Meeresforschung
    Type of Medium: Series available for loan
    Pages: 149 S. , graph. Darst.
    ISSN: 1618-3193
    Series Statement: Berichte zur Polar- und Meeresforschung 498
    Classification:
    Oceanology
    Language: German
    Location: AWI Reading room
    Location: Lower compact magazine
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  • 6
    Series available for loan
    Series available for loan
    Bremerhaven : Alfred-Wegener-Inst. für Polar- und Meeresforschung
    Associated volumes
    Call number: ZSP-168-499 ; ZS-090(499)
    In: Berichte zur Polar- und Meeresforschung
    Type of Medium: Series available for loan
    Pages: VI, 180 S.
    ISSN: 1618-3193
    Series Statement: Berichte zur Polar- und Meeresforschung 499
    Classification:
    Oceanology
    Language: German
    Location: AWI Reading room
    Location: Lower compact magazine
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