Channel-floodplain connectivity during an extreme flood event: Implications for erosion, deposition and sediment delivery

Croke, Jacky, Fryirs, Kirstie and Thompson, Christopher (2013) Channel-floodplain connectivity during an extreme flood event: Implications for erosion, deposition and sediment delivery. Earth Surface Processes and Landforms, 38 12: 1444-1456. doi:10.1002/esp.3430


Author Croke, Jacky
Fryirs, Kirstie
Thompson, Christopher
Title Channel-floodplain connectivity during an extreme flood event: Implications for erosion, deposition and sediment delivery
Journal name Earth Surface Processes and Landforms   Check publisher's open access policy
ISSN 0197-9337
1096-9837
Publication date 2013
Year available 2013
Sub-type Article (original research)
DOI 10.1002/esp.3430
Open Access Status
Volume 38
Issue 12
Start page 1444
End page 1456
Total pages 13
Place of publication Chichester, West Sussex, United Kingdom
Publisher ohn Wiley and Sons Ltd.
Collection year 2013
Language eng
Formatted abstract
The term connectivity has emerged as a powerful concept in hydrology and geomorphology and is emerging as an innovative component of catchment erosion modeling studies. However, considerable confusion remains regarding its definition and quantification, especially as it relates to fluvial systems. This confusion is exacerbated by a lack of detailed case studies and by the tendency to treat water and sediment separately. Extreme flood events provide a useful framework to assess variability in connectivity, particularly the connection between channels and floodplains. The catastrophic flood of January 2011 in the Lockyer valley, southeast Queensland, Australia provides an opportunity to examine this dimension in some detail and to determine how these dynamics operate under high flow regimes. High resolution aerial photographs and multi-temporal LiDAR digital elevation models (DEMs), coupled with hydrological modeling, are used to assess both the nature of hydrologic and sedimentological connectivity and their dominant controls. Longitudinal variations in flood inundation extent led to the identification of nine reaches which displayed varying channel-floodplain connectivity. The major control on connectivity was significant non-linear changes in channel capacity due to the presence of notable macrochannels which contained a>3000 average recurrence interval (ARI) event at mid-catchment locations. The spatial pattern of hydrological connectivity was not straight-forward in spite of bankfull discharges for selected reaches exceeding 5600m3 s-1. Data indicate that the main channel boundary was the dominant source of sediment while the floodplains, where inundated, were the dominant sinks. Spatial variability in channel-floodplain hydrological connectivity leads to dis-connectivity in the downstream transfer of sediments between reaches and affected sediment storage on adjacent floodplains. Consideration of such variability for even themost extreme flood events, highlights the need to carefully consider non-linear changes in key variables such as channel capacity and flood conveyance in the development of a quantitative connectivity index.
Keyword Channel floodplain linkages
Extreme events
Lateral connectivity
Lockyer Valley
Sedimentological connectivity
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status Non-UQ

Document type: Journal Article
Sub-type: Article (original research)
Collection: School of Geography, Planning and Environmental Management Publications
 
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Created: Wed, 26 Nov 2014, 11:30:24 EST by Helen Smith on behalf of School of Geography, Planning & Env Management