Debris flow dominated alluvial fans in the Victorian high country indicate that landscape denudation through the Holocene has been dominated by post-bushfire runoff events

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dc.contributor.authorMarren, Pen_AU
dc.contributor.authorKermode, SJen_AU
dc.contributor.authorNyman, Pen_AU
dc.date.accessioned2020-06-10T09:39:31Zen_AU
dc.date.available2020-06-10T09:39:31Zen_AU
dc.date.issued2014-06-29en_AU
dc.date.statistics2020-05-28en_AU
dc.description.abstractBushfires play a major role in shaping the Australian landscape. Whilst the role of fire in shaping and changing vegetation assemblages is relatively well understood, there is still debate about the significance of fire in driving landscape denudation, relative to other processes, such as major rainfall and flood events. Studies of post-fire landscape impact of recent bushfires indicate that the response is sensitive to the frequency and magnitude of extreme bushfires and intense rainstorms, with the greatest response occurring when storms occur in the post-fire period before vegetation has recovered. Where storm events occur shortly after a major bushfire, hillslope erosion is enhanced, due to debris flows and erosion of both primary hillslope sediment and sediment stored in hillslope channel networks. We excavated nine trenches, in five alluvial fans at the base of hillslopes on the floodplain of the Nariel valley, northeast Victoria. This area was burnt by the 1939 and 2003 bushfires, although some of the fans were unburnt in 2003. The trenches were up to 3.5 m deep, and in four cases intersected the underlying floodplain sediment at the base of the trench, indicating that they provide a full record of sedimentation for that sector of the fan. Fan stratigraphy consisted of sub-horizontal (parallel to the fan surface) units 0.3–0.5 m thick, with occasional units 1–1.2m thick, and cross-cutting channelized units. Debris flow deposits accounted for 80–90 % of the observed sediments, with water-laid gravels and soil units forming the remainder. Most soil layers were burnt, and most (but not all) debris flow units contained charcoal. A typical stratigraphy consisted of 6–8 debris flow units per fan, with four units containing a fire signature or overlying a burnt soil layer. Radiocarbon dating of the fireassociated units is underway: preliminary results will be reported at the AQUA meeting.en_AU
dc.identifier.citationMarren, P., Kermode, S., & Nyman, P. (2014). Debris flow dominated alluvial fans in the Victorian high country indicate that landscape denudation through the Holocene has been dominated by post-bushfire runoff events. Paper presented at the AQUA Biennial Meeting The Grand Hotel, Mildura, 29th June - 4th July, 2014.en_AU
dc.identifier.conferenceenddate4 July 2014en_AU
dc.identifier.conferencenameAQUA Biennial Meetingen_AU
dc.identifier.conferenceplaceMildura, Victoriaen_AU
dc.identifier.conferencestartdate29 June 2014en_AU
dc.identifier.govdoc9601en_AU
dc.identifier.urihttps://aqua.org.au/wp-content/uploads/2013/06/AQUA2014-program.pdfen_AU
dc.identifier.urihttp://apo.ansto.gov.au/dspace/handle/10238/9541en_AU
dc.language.isoenen_AU
dc.publisherAustralasian Quaternary Association Incen_AU
dc.subjectVictoriaen_AU
dc.subjectAustraliaen_AU
dc.subjectQuaternary perioden_AU
dc.subjectFiresen_AU
dc.subjectPlantsen_AU
dc.subjectFloodsen_AU
dc.subjectStormsen_AU
dc.subjectErosionen_AU
dc.titleDebris flow dominated alluvial fans in the Victorian high country indicate that landscape denudation through the Holocene has been dominated by post-bushfire runoff eventsen_AU
dc.typeConference Abstracten_AU
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