Sedimentologically significant tributaries

catchment-scale controls on sediment (dis)connectivity in the Lockyer Valley, SEQ, Australia

Peyton E. Lisenby*, Kirstie A. Fryirs

*Corresponding author for this work

    Research output: Contribution to journalArticle

    16 Citations (Scopus)

    Abstract

    The nature of catchment-scale sediment (dis)connectivity is the primary influence on sediment delivery to trunk streams and controls the particle size distribution of channel bed sediments. Here, we examine the distribution of major sediment buffers (floodplains, terraces, alluvial fans, trapped tributary fills), barriers (weirs), and effective catchment area (i.e. sediment contributing area) to characterize the potential for coarse sediment (dis)connectivity in 20 tributaries of Lockyer Creek, in the Lockyer Valley, SEQ. We then analyse the distribution of trunk stream sedimentary links to determine how certain tributaries or disconnecting features (buffers and barriers) influence downstream patterns of bed sediment fining along Lockyer Creek. We find that buffering increases downstream in the Lockyer Valley, and that tributary position and shape influence the space available for sediment buffering. Correspondingly, the spatial extent of sediment buffers impacts the distribution of effective catchment area, which influences the sedimentological significance of individual tributaries. Tributary sediment connectivity, the extent of overbank flows (floodwater zones), and weir locations all exert an additional influence on the distribution of sediment links along the trunk stream. These controls are related to the physiographic and climatic setting of the Lockyer Valley, and anthropogenic influences in this system. We conclude that controls on sediment connectivity and bed load sediment characteristics are highly variable between catchments, and that sediment (dis)connectivity merits equal consideration with tributary basin/channel size when determining controls on tributary-trunk stream relationships and channel sediment regime.

    Original languageEnglish
    Pages (from-to)1493-1504
    Number of pages12
    JournalEarth Surface Processes and Landforms
    Volume42
    Issue number10
    DOIs
    Publication statusPublished - Aug 2017

    Keywords

    • buffer
    • downstream sediment fining
    • effective catchment area
    • sediment budget
    • sedimentary links

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