Geomorphic effects, flood power, and channel competence of a catastrophic flood in confined and unconfined reaches of the upper Lockyer valley, southeast Queensland, Australia

Thompson, Chris; Croke, Jacky

doi:10.1016/j.geomorph.2013.05.006

Cited by 157 publications

(104 citation statements)

References 56 publications

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“…The presence of pre-and post-2011 flood lidar in the Lockyer Valley, Queensland, allows for such an assessment. Previous studies in the region have focussed on the alluvial reaches (or variations in responses between confined and unconfined reaches) and bank erosion within agricultural and semi-agricultural settings Grove et al, 2013;Thompson and Croke, 2013). In contrast, the main aim of this study is to assess the channel response in forested bedrock-confined settings to an extreme event and examine the current channel based on existing morphological classification systems by utilising multi-temporal lidar DEMs and field surveys.…”

Section: Role Of Large Floods In Channel Evolutionmentioning

confidence: 99%

“…The roughness estimates and field channel survey data were used to calculate values for predicted discharge, shear stress, and stream power with values of discharge constrained in the most downstream reach by previous basin-scale modelling (see Thompson and Croke, 2013). This basin-scale modelling provides an important independent check against the validity of the chosen n values used for the final estimates.…”

Section: Entrainment Threshold Calculationsmentioning

confidence: 99%

“…Peak discharge for the 2011 flood, based on flood scarring and estimated Manning's n values equivalent to those used by Thompson and Croke (2013) in their catchmentwide modelling for the same event, yields discharge values ranging from 415 to 933 m 3 s −1 , shear stress values up to 388 N m −2 and cross-sectional averaged unit stream power of 1077 W m −2 (Table 2) for an event that was 6-8 m flow depth. All three entrainment approaches predict the mobilisation of the D 50 in each of the reaches in the 2011 flood, but with the Shields parameter predicting insufficient competence to transport the D max (Table 3).…”

Section: Sediment Entrainment In An Extreme Eventmentioning

confidence: 99%

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Hitting rock bottom: morphological responses of bedrock-confined streams to a catastrophic flood

et al. 2015

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Abstract. The role of extreme events in shaping the Earth's surface is one that has held the interests of Earth scientists for centuries. A catastrophic flood in a tectonically quiescent setting in eastern Australia in 2011 provides valuable insight into how semi-alluvial channels respond to such events. Field survey data (3 reaches) and desktop analyses (10 reaches) with catchment areas ranging from 0.5 to 168 km 2 show that the predicted discharge for the 2011 event ranged from 415 to 933 m 3 s −1 , with unit stream power estimates of up to 1077 W m −2 . Estimated entrainment relationships predict the mobility of the entire grain-size population, and field data suggest the localised mobility of boulders up to 4.8 m in diameter. Analysis of repeat lidar data demonstrates that all reaches (field and desktop) were areas of net degradation via extensive scouring of coarse-grained alluvium with a strong positive relationship between catchment area and normalised erosion (R 2 = 0.72-0.74). The extensive scouring in the 2011 flood decreased thalweg variance significantly removing previous step pools and other coarse-grained in-channel units, forming lengths of plane-bed (cobble) reach morphology. This was also accompanied by the exposure of planar bedrock surfaces, marginal bedrock straths and bedrock steps. Post-flood field data indicate a slight increase in thalweg variance as a result of the smaller 2013 flood rebuilding the alluvial overprint with pool-riffle formation. However, the current form and distribution of channel morphological units does not conform to previous classifications of bedrock or headwater river systems. This variation in postflood form indicates that in semi-alluvial systems extreme events are significant for re-setting the morphology of in-channel units and for exposing the underlying lithology to ongoing erosion.

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Section: Role Of Large Floods In Channel Evolutionmentioning

confidence: 99%

Section: Entrainment Threshold Calculationsmentioning

confidence: 99%

Section: Sediment Entrainment In An Extreme Eventmentioning

confidence: 99%

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Hitting rock bottom: morphological responses of bedrock-confined streams to a catastrophic flood

et al. 2015

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“…34,35 Multitemporal coverage of LiDAR and optical image data, before and after a catastrophic flood, allowed erosion volumes and the relative contributions from different erosion processes to be quantified along a 100-km stretch of the Lockyer Creek in Queensland, Australia. 36,37 The combination of LiDAR and optical data was found essential for feature delineation and subsequent process interpretation.…”

Section: Remotely Sensed Approachesmentioning

confidence: 99%

Assessing stream bank condition using airborne LiDAR and high spatial resolution image data in temperate semirural areas in Victoria, Australia

Johansen

Grove

Denham

2013

J. Appl. Remote Sens

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Abstract. Stream bank condition is an important physical form indicator for streams related to the environmental condition of riparian corridors. This research developed and applied an approach for mapping bank condition from airborne light detection and ranging (LiDAR) and high-spatial resolution optical image data in a temperate forest/woodland/urban environment. Field observations of bank condition were related to LiDAR and optical image-derived variables, including bank slope, plant projective cover, bank-full width, valley confinement, bank height, bank top crenulation, and ground vegetation cover. Image-based variables, showing correlation with the field measurements of stream bank condition, were used as input to a cumulative logistic regression model to estimate and map bank condition. The highest correlation was achieved between field-assessed bank condition and image-derived average bank slope (R 2 ¼ 0.60, n ¼ 41), ground vegetation cover (R 2 ¼ 0.43, n ¼ 41), bank width/height ratio (R 2 ¼ 0.41, n ¼ 41), and valley confinement (producer's accuracy ¼ 100%, n ¼ 9). Crossvalidation showed an average misclassification error of 0.95 from an ordinal scale from 0 to 4 using the developed model. This approach was developed to support the remotely sensed mapping of stream bank condition for 26,000 km of streams in Victoria, Australia, from 2010 to 2012.

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“…Mobile laser scanning, for example from car, backpack and boat, provide practical scanning angle to survey channel banks, bar lobes and vertical surfaces, and also data collection over large channel bars has been enhanced with the method (Vaaja et al, 2011;Kasvi et al, 2015;Kukko et al, 2015). Digital elevation models produced from LiDAR data have been applied for detecting the geomorphic effects of different discharge 5 events (Hauer and Habersack, 2009;Croke et al, 2013;Thompson and Croke, 2013;Nardi and Rinaldi, 2015) and for recording and calibrating sediment transport models . These reveal the reorganization of the channel morphology due to flood events even over large areas with great detail .…”

Section: Introductionmentioning

confidence: 99%

Topographical changes caused by moderate and small floods in a gravelly ephemeral river – 2D morphodynamic simulation approach

Lotsari

Calle

Benito

et al. 2017

Preprint

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Abstract. In ephemeral rivers, channel morphology represents a snapshot at the end of a succession of geomorphic changes performed by a flood. In most cases, the channel shape and bedform evolution during different phases of a flood hydrograph 15 are not recognized from field evidence. This paper analyzes the capabilities of morphodynamic modelling (Delft 2D) for resolving the evolution of a gravelly ephemeral river channel during consecutive, moderate-and low-magnitude discharge events. We pursue for schematic concepts for simulations in ephemeral gravely rivers that provide an outcome with the closest similarity to the post-flood reality. Based on the simulations, we analyze the morphodynamic evolution of Rambla de la Viuda The spatially varying grain size data and transport equations were the most important factors, in addition to the quality of recorded discharge, for the simulation results of the channel evolution. The total load equation worked better, compared to the 25 deterministic equation. The erosion and deposition can be in total greater during the long-lasting receding phase than during the rising phase. The deposition and erosion peaks are predicted to occur at the beginning of the moderate-magnitude discharge event, whereas deposition dominates throughout the event. On the contrary, the low-magnitude discharge event only experiences the peak of channel changes after the discharge peak. These different predicted erosion/deposition patterns suggest a hysteresis effect on the morphodynamic changes, and stress the importance of previous flood history (timing, succession and 30 magnitude) in understanding the geomorphic response of gravelly ephemeral rivers.Earth Surf. Dynam. Discuss., https://doi

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Geomorphic effects, flood power, and channel competence of a catastrophic flood in confined and unconfined reaches of the upper Lockyer valley, southeast Queensland, Australia

Cited by 157 publications

References 56 publications

Hitting rock bottom: morphological responses of bedrock-confined streams to a catastrophic flood

Hitting rock bottom: morphological responses of bedrock-confined streams to a catastrophic flood

Assessing stream bank condition using airborne LiDAR and high spatial resolution image data in temperate semirural areas in Victoria, Australia

Topographical changes caused by moderate and small floods in a gravelly ephemeral river – 2D morphodynamic simulation approach

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