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dc.contributor.authorShellberg, JG
dc.contributor.authorSpencer, J
dc.contributor.authorBrooks, AP
dc.contributor.authorPietsch, TJ
dc.date.accessioned2018-10-05T04:32:21Z
dc.date.available2018-10-05T04:32:21Z
dc.date.issued2016
dc.identifier.issn0169-555X
dc.identifier.doi10.1016/j.geomorph.2016.04.021
dc.identifier.urihttp://hdl.handle.net/10072/99643
dc.description.abstractAlong low gradient rivers in northern Australia, there is widespread gully erosion into unconfined alluvial deposits of active and inactive floodplains. On the Mitchell River fluvial megafan in northern Queensland, river incision and fan-head trenching into Pleistocene and Holocene megafan units with sodic soils created the potential energy for a secondary cycle of erosion. In this study, rates of alluvial gully erosion into incipiently-unstable channel banks and/or pre-existing floodplain features were quantified to assess the influence of land use change following European settlement. Alluvial gully scarp retreat rates were quantified at 18 sites across the megafan using recent GPS surveys and historic air photos, demonstrating rapid increases in gully area of 1.2 to 10 times their 1949 values. Extrapolation of gully area growth trends backward in time suggested that the current widespread phase of gullying initiated between 1880 and 1950, which is post-European settlement. This is supported by young optically stimulated luminescence (OSL) dates of gully inset-floodplain deposits, LiDAR terrain analysis, historic explorer accounts of earlier gully types, and archival records of cattle numbers and land management. It is deduced that intense cattle grazing and associated disturbance concentrated in the riparian zones during the dry season promoted gully erosion in the wet season along steep banks, adjacent floodplain hollows and precursor gullies. This is a result of reduced native grass cover, increased physical disturbance of soils, and the concentration of water runoff along cattle tracks, in addition to fire regime modifications, episodic drought, and the establishment of exotic weed and grass species. Geomorphic processes operating over geologic time across the fluvial megafan predisposed the landscape to being pushed by land used change across an intrinsically close geomorphic threshold towards instability. The evolution of these alluvial gullies is discussed in terms of their initiation, development, future growth, and stabilisation, and the numerous natural and anthropogenic factors influencing their erosion.
dc.description.peerreviewedYes
dc.languageEnglish
dc.language.isoeng
dc.publisherElsevier
dc.relation.ispartofpagefrom105
dc.relation.ispartofpageto120
dc.relation.ispartofjournalGeomorphology
dc.relation.ispartofvolume266
dc.subject.fieldofresearchGeology
dc.subject.fieldofresearchPhysical geography and environmental geoscience
dc.subject.fieldofresearchGeomorphology and earth surface processes
dc.subject.fieldofresearchRegolith and landscape evolution
dc.subject.fieldofresearchcode3705
dc.subject.fieldofresearchcode3709
dc.subject.fieldofresearchcode370901
dc.subject.fieldofresearchcode370906
dc.titleDegradation of the Mitchell River fluvial megafan by alluvial gully erosion increased by post-European land use change, Queensland, Australia
dc.typeJournal article
dc.type.descriptionC1 - Articles
dc.type.codeC - Journal Articles
dcterms.licensehttp://creativecommons.org/licenses/by-nc-nd/4.0/
dc.description.versionAccepted Manuscript (AM)
gro.facultyGriffith Sciences, Griffith School of Environment
gro.rights.copyright© 2016 Elsevier. Licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International Licence (http://creativecommons.org/licenses/by-nc-nd/4.0/) which permits unrestricted, non-commercial use, distribution and reproduction in any medium, providing that the work is properly cited.
gro.hasfulltextFull Text
gro.griffith.authorBrooks, Andrew P.
gro.griffith.authorSpencer, John R.
gro.griffith.authorShellberg, Jeffrey G.
gro.griffith.authorPietsch, Tim


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