A new approach to defining the surface-subsurface transition in a gravel bed

Heather Haynes, Anne-Marie Ockelford, Elisa Vignaga, William Holmes

    Research output: Contribution to journalArticle

    Abstract

    The vertical structure of river beds varies temporally and spatially in response to hydraulic regime, sediment mobility, grain size distribution and faunal interaction. Implicit are changes to the active layer depth and bed porosity, both critical in describing processes such as armour layer development, surface-subsurface exchange processes and siltation/sealing. Whilst measurements of the bed surface are increasingly informed by quantitative and spatial measurement techniques (e.g. laser displacement scanning), material opacity has precluded the full 3-D bed structure analysis required to accurately define the surface-subsurface transition. To overcome this problem, this paper provides Magnetic Resonance Imaging data of vertical bed porosity profiles. Uniform and bimodal (sg = 2.1) sand-gravel beds are considered following restructuring under sub-threshold flow durations of 60 and 960 minutes. MRI data are compared to traditional 2.5-D laser displacement scans and six robust definitions of the surface-subsurface transition are provided; these form the focus of discussion.
    Original languageEnglish
    Pages (from-to)1589-1606
    JournalActa Geophysica
    Volume60
    Issue number6
    Early online date1 Oct 2012
    DOIs
    Publication statusPublished - 2012

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    gravel
    laser
    porosity
    siltation
    active layer
    river bed
    sealing
    grain size
    hydraulics
    sand
    sediment

    Cite this

    Haynes, Heather ; Ockelford, Anne-Marie ; Vignaga, Elisa ; Holmes, William. / A new approach to defining the surface-subsurface transition in a gravel bed. In: Acta Geophysica. 2012 ; Vol. 60, No. 6. pp. 1589-1606.
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    abstract = "The vertical structure of river beds varies temporally and spatially in response to hydraulic regime, sediment mobility, grain size distribution and faunal interaction. Implicit are changes to the active layer depth and bed porosity, both critical in describing processes such as armour layer development, surface-subsurface exchange processes and siltation/sealing. Whilst measurements of the bed surface are increasingly informed by quantitative and spatial measurement techniques (e.g. laser displacement scanning), material opacity has precluded the full 3-D bed structure analysis required to accurately define the surface-subsurface transition. To overcome this problem, this paper provides Magnetic Resonance Imaging data of vertical bed porosity profiles. Uniform and bimodal (sg = 2.1) sand-gravel beds are considered following restructuring under sub-threshold flow durations of 60 and 960 minutes. MRI data are compared to traditional 2.5-D laser displacement scans and six robust definitions of the surface-subsurface transition are provided; these form the focus of discussion.",
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    Haynes, H, Ockelford, A-M, Vignaga, E & Holmes, W 2012, 'A new approach to defining the surface-subsurface transition in a gravel bed', Acta Geophysica, vol. 60, no. 6, pp. 1589-1606. https://doi.org/10.2478/s11600-012-0067-z

    A new approach to defining the surface-subsurface transition in a gravel bed. / Haynes, Heather; Ockelford, Anne-Marie; Vignaga, Elisa; Holmes, William.

    In: Acta Geophysica, Vol. 60, No. 6, 2012, p. 1589-1606.

    Research output: Contribution to journalArticle

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