Alluvium of antiquity: Polycyclic terraces in a confined bedrock valley

Kermode, Stephanie J; Cohen, Tim J; Reinfelds, Ivars; Nanson, Gerald C.; Pietsch, Tim

doi:10.1016/j.geomorph.2011.11.012

Cited by 12 publications

(22 citation statements)

References 36 publications

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“…5 of these cases has not been clearly documented (Brakenridge, 1984;Nanson, 1986;Tooth et al, 2002Tooth et al, , 2004Tooth et al, , 2007Marren et al, 2006;Cohen and Nanson, 2008;Kermode et al, 2012Kermode et al, , 2015Keen-Zebert et al, 2013). Further, existing classifications of floodplain development in alluvial channels (e.g., Nanson and Croke, 1992) may not necessarily apply to glacially conditioned watersheds (Phillips and Desloges, 2015a) where channels, particularly in mid-watershed and downstream reaches, are often partly confined forming floodplains as narrow, discontinuous surfaces, similar to the partly confined, mixed alluvium-bedrock settings of Fryirs and Brierley (2010).…”

Section: Accepted Manuscriptmentioning

confidence: 99%

“…Specific stream power and floodplain confinement data from studies in various bedrock (Nanson, 1986;Tooth et al, 2004;Marren et al, 2006;Cohen and Nanson, 2008;Kermode et al, 2012), and glaciogenic (Nanson, 1980;Walker et al, 1997;Croil, 2002;Brooks, 2003;Thayer, 2012;Stewart and Desloges, 2014) environments were collected and plotted against each other, segregated by their dominant form of floodplain accretion (i.e., lateral or vertical accretion) as described in each study. Oblique accretion was grouped in with lateral accretion.…”

Section: Floodplain Classification Frameworkmentioning

confidence: 99%

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Floodplain morphology, sedimentology, and development processes of a partially alluvial channel

Thayer

Ashmore

2016

Geomorphology

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Section: Accepted Manuscriptmentioning

confidence: 99%

Section: Floodplain Classification Frameworkmentioning

confidence: 99%

Floodplain morphology, sedimentology, and development processes of a partially alluvial channel

Thayer

Ashmore

2016

Geomorphology

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“…Floodplain stratigraphy across four catchments is characterised by alternating, clearly bound units of silt or sand, which are indicative of vertical accretion associated with laterally stable channels. This is similar to the findings of other floodplain studies in eastern Australia, which highlight the dominance of fine-grained floodplains built by vertical accretion (Nanson, 1986;Nanson et al, 2003;Cohen and Nanson, 2008;Kermode et al, 2012;Leonard and Nott, 2015b). The clearly bound sedimentary units in Wet Tropics floodplains are similar to those described in the Amazon Basin, where ENSO is considered the key driver of floodplain formation (Aalto et al, 2003).…”

Section: Thesis Key Findingssupporting

confidence: 87%

“…River responses are therefore amplified in partly confined settings and fluvial landforms, sedimentology and age characteristics tend to be highly variable (Nanson, 1986;Nanson et al, 2003;Coulthard et al, 2005;Cohen and Nanson, 2008;Richardson et al, 2013;Leonard and Nott, 2015). However, it must also be acknowledged that these same reach characteristics may lead to reduced preservation potential of alluvium (Kermode et al, 2012).…”

Section: Translating Theory Into Practice: Implications For the Expermentioning

confidence: 99%

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River response and climate change in the Wet Tropics, northeast Queensland Australia

Hughes¹

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An improved understanding of the relationship between climate change and river response is critical for predicting future trajectories of fluvial landforms. This is particularly important with climate change projections showing an increase in extreme events such as floods and cyclones. In Australia and internationally, a valuable record of river response has been developed from the morphologic and sedimentologic archives of river terraces and floodplains, mainly in temperate regions. These studies reveal the key role of climate over timescales ranging from 100 kyr glacial/interglacial cycles through to decadal cycles driven by the El Niño Southern Oscillation (ENSO). However, the understanding of fluvial records in the humid (wet) tropics is comparatively poor despite these regions being geomorphic hotspots for catastrophic change. The relevance of key geomorphic concepts to wet tropical rivers is largely unknown and therefore the knowledge gained from studying these settings is invaluable. The overarching aim of this thesis is to characterise the nature of regional river response and its relationship to climatic change in the Wet Tropics of tropical northeast Queensland, Australia. Chapters 2 to 6 explore the various aspects of this research question and an overall synthesis of the thesis key findings and future research priorities is presented in Chapter 7.Chapter 2 presents the research on terrace distribution and chronostratigraphic characteristics to provide the overall spatial context of river landforms across five catchments. Two terraces are correlated and mapped across the study area, while the terrace chronology details two periods of aggradation-incision that post-date the Last Glacial Maximum. Explanations for spatial differences in terrace preservation are explored using a range of catchment force-resistance variables with the results underpinning a new conceptual model of terrace types and preservation processes. Author A. Sharma Data collection (sediment dating data in Table 3) (10%).v i i Contributions by others to the thesisChapter 2: Hughes, K., Croke, J., Bartley, R., Thompson, C., Sharma, A.Alluvial terrace preservation in the Wet Tropics, northeast Queensland, Australia. KH was responsible for 70% of conception and design, 90% of data collection, 80% of data analysis and interpretation, and 60% of writing and editing. JC was responsible for 30% of conception and design, 20% of data analysis and interpretation, and 20% of writing and editing. RB was responsible for 10% of writing and editing. CT was responsible for 10% of data analysis and interpretation and 10% of writing and editing. AS was responsible for 10% of data collection.Chapter 3: Hughes, K., Croke, J., Thompson, C., Sharma, A., K. Tilly.KH was responsible for 70% of conception and design, 90% of data collection, 80% of data analysis and interpretation, and 75% of writing and editing. JC was responsible for 30% of conception and design, 10% of data analysis and interpretation, and 20% of writing and editing. CT was respon...

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Determining the impact of the Holocene highstand at the coastal‐fluvial interface, Shoalhaven River, south‐eastern Australia

Kermode

Gibling

Jones

et al. 2013

Earth Surf Processes Landf

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With enhanced rates of sea-level rise predicted for the next century, the upstream extent of sea-level influence across coastal plains is a topic of public importance. Australian coastal rivers provide a testing ground for exploring this issue because the area is tectonically stable, was not glaciated, and experienced a Holocene highstand between 7.4 and 2ka of up to 1.5m above Australian Height Datum (AHD). In the Shoalhaven River of New South Wales, investigation of a confined bedrock reach at Wogamia, 32km inland, has identified a unit of dark, cohesive silt and sand with marine diatoms, shell fragments, and enhanced pyrite content, interpreted as estuarine. The unit is up to 13m thick, thickens downstream, and is overlain by fluvial channel and floodplain deposits. The estuarine unit on-laps a remnant Pleistocene terrace and extends to approximately +2.2m AHD. Optically stimulated luminescence (OSL) and radiocarbon ages suggest that estuarine deposition commenced prior to 7.8kacal bp, predating the highstand by~500years, and that marine influence in the area continued to 5.3±0.7ka. During this period, a delta probably persisted at Wogamia, where a narrow upstream reach opens out, and subsequently advanced to fill the broad Shoalhaven coastal embayment. Although the effect of sea-level rise depends on many factors, the results suggest that, during a highstand at or above present sea level, a strong marine influence may extend for tens of kilometres inland and penetrate confined bedrock reaches landward of coastal embayments. ABSTRACTWith enhanced rates of sea-level rise predicted for the next century, the upstream extent of sea level influence across coastal plains is a topic of public importance. Australian coastal rivers provide a testing ground for exploring this issue because the area is tectonically stable, was not glaciated, and experienced a Holocene highstand between 7.4 to 2 ka and up to 1.5 m above Australian Height Datum (AHD). In the Shoalhaven River of New South Wales, investigation of a confined bedrock reach at Wogamia, 32 km inland, has identified a unit of dark, cohesive silt and sand with marine diatoms, shell fragments, and enhanced pyrite content, interpreted as estuarine. The unit is up to 13 m thick, thickens downstream, and is overlain by fluvial channel and floodplain deposits. The estuarine unit on-laps a remnant Pleistocene terrace and extends to approximately +2.2 m AHD. OSL and radiocarbon ages suggest that estuarine deposition commenced prior to 7.8 ka cal B.P., predating the highstand by ~ 500 years, and that marine influence in the area continued to 5.3 ± 0.7 ka. During this period, a delta probably persisted at Wogamia, where a narrow upstream reach opens out, and subsequently advanced to fill the broad Shoalhaven coastal embayment. Although the effect of sea-level rise depends on many factors, the results suggest that, during a highstand at or above present sea level, a strong marine influence may extend for tens of kilometres inland and penetrate confined bedrock re...

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Alluvium of antiquity: Polycyclic terraces in a confined bedrock valley

Cited by 12 publications

References 36 publications

Floodplain morphology, sedimentology, and development processes of a partially alluvial channel

Floodplain morphology, sedimentology, and development processes of a partially alluvial channel

River response and climate change in the Wet Tropics, northeast Queensland Australia

Determining the impact of the Holocene highstand at the coastal‐fluvial interface, Shoalhaven River, south‐eastern Australia

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