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Big Flood Newsletter Issue 6, October 2015
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Issue 6: October, 2015
 
Welcome to our October Newsletter. Time feels like it is speeding up! We are at a stage in the project now when many of our results are starting to illuminate the ‘bigger picture’ and maybe even challenge some of our initial assumptions and hypotheses. This is an exciting stage in a project where results from the multiple stages are emerging and adding to a deeper understanding. Special thanks to Ashneel Sharma for pushing through his personal injuries and keeping up the output from the OSL machine - the significance of which is briefly discussed for Stage 1 below. I also extend a warm welcome to Robert and Pim, both from WUR in the Netherlands, who will be undertaking some studies in the Lockyer over the next three months as part of their degree.  Thanks too to Heather Haines who recently organised a writing workshop for the group at DSITI as a way to encourage productivity with many of the PhD students now actively writing chapters or papers. Although there are no 'formal' Industry Partner workshops planned for this year, both Chris and I are regularly involved in catch-ups and presentations to Industry. I am presenting an update to the LVRC again in November and Chris has been heavily involved in the initiatives with the Council of Mayors. Next year we will be presenting a series of workshops and forums for Industry and more details on these will follow by the end of the year.
 
CONGRATULATIONS to Stage 3 leader Kirstie Fryris and Stage 4 leader Chris Thompson. Kirstie is this year's recipient of the Gordon Warwick Medal which is made for excellence in geomorphological research by someone within 15 years of being awarded their doctorate (i.e. time since graduation). Kirstie is spending a month in the UK working with a range of colleagues and giving keynotes at two conferences, the British Society for Geomorphology and the European Commission COST Connectivity working parties. She will be presenting some of the Lockyer sediment (dis)connectivity work at the latter event.
Chris Thompson has been awarded a Visiting Scientist grant to work landscape evolution modelling with Dr Arnaud Temme and the LAPSUS research group at Wageningen University, Netherlands.

Stage Leader Updates

Stage 1 – Update

 
Lead CI - Jacky Croke
PhD Students - James Daley and Daryl Lam

From a geomorphological perspective, there are a few ‘weird’ things about the Lockyer Creek. For example, the highly angular dog-leg changes in channel direction towards the confluence with the mid-Brisbane (Fig 1), but also the width of the alluvial valley floor relative to the current size and dimensions of the present Lockyer (Fig 1).
Figure 1 shows the highly angular dog-leg changes in channel direction towards the confluence with the mid-Brisbane.
It’s hard to imagine that the Lockyer we see today could have ‘produced’ such a wide alluvial plain. Bernie Powell (formerly from DSITI) conducted a very detailed study of the alluvial soils of the Lockyer in his Master’s thesis in 19871. Bernie’s findings have been invaluable to us as we have pieced together some more understanding of how the Lockyer has evolved over time. In his study, Bernie made reference to the existence of multiple channels in the valley – referred to a braided channel system, where the valley is occupied by many channels. The term braided has evolved and probably wouldn’t be used today, but nonetheless the concept of multiple channels is intriguing. Evidence compiled within the project would now also suggest that the Lockyer has evolved from a multiple channel system to a single system. James Daley (see report below), in his recently submitted paper to ESPL, highlights the existence of multiple bedrock channels across the valley floor in the area around Helidon. These bedrock ‘slots’ are a major control on the ability of the present channel system to adjust to changes in sediment and discharges - in effect they are a major control on the existence of what we have referred to as ‘macrochannels’ and hence, the size of flood these channels can accommodate. We have also seen evidence of multiple channels in the groundwater borehole records further downstream, where at least 3-4 channels have been identified in valley fill units. Recently returned OSL dates from channel sands in the base of these older channels, many of which are significantly larger (an order of magnitude) than the present Lockyer, indicate that the Lockyer has avulsed or switched channel locations numerous times since 140ka ago. Why does this matter ? Well, developing a deeper understanding of the local, valley-specific controls on how the present Lockyer adjusts is fundamental to future management efforts. In a system which has a recognised tendency to switch location or avulse, we need to be mindful of practices which may push the system closer to this threshold. One example of that is artificial levee construction. Chris Thompson’s work on describing the various stages of a Channel Evolution Model (CEM) (see Stage 4 report below) is also an illustration of why specific understanding of a catchment’s history, and its ability to adjust to antecedent controls, is fundamental to any catchment-wide management efforts. This longer-term evolution is often considered ‘too old’ to be of relevance to current management issues but this work highlights the many ways in which good catchment management decisions can only be built on a deeper understanding of how river systems have evolved in the past. Multiple time periods need to be considered in guiding future plans.

Finally, I have been collaborating with Tessa Vance from the Antarctic CRC and Anthony Kiem (University of Newcastle) recently about comparisons between their detailed, high resolution record of changes in floods and droughts inferred from sea salt concentrations in the Law Dome ice core with the flood record produced from the Lockyer. This forms part of a submission to the journal Global and Planetary Change in the coming weeks.
 
1Powell B. 1987. Nature, distribution and origin of soils on an alluvial landscape in the Lockyer Valley, South-east Queensland. Master of Rural Science Thesis, University of New England.

Stage 2 – Update

 
Lead CI - Jon Olley
PhD Students  - Heather Haines and Jack Coates-Marnane

During the past quarter the majority of work undertaken in Stage 2 has involved the two PhD projects.  Jack has extended his geochemical analysis across the Moreton Bay basin.  Heather has been working on developing her Lamington chronology with the data from ANSTO progressing this component.  Heather and Justine Kemp represented Stage 2 at the INQUA Congress in Nagoya, Japan in July with excellent feedback on papers related to this project.  Several papers are in preparation with the hopes of submission within the next quarter.

Stage 3 – Update

 
Lead CI - Kirstie Fryirs
PhD candidate – Peyton Lisenby (MQ)

Stage 3 is currently in an intense data collection and analysis phase. This work now revolves largely around the PhD work of Peyton Lisenby which is reported on elsewhere in this newsletter. Peyton recently spent two weeks based at UQ and undertook some fieldwork in the Lockyer valley tributary systems. The paper by Lisenby and Fryirs on geomorphic change in the tributary systems of Laidley, Tenthill and Buaraba is under review at Water Resources Research.
 

Stage 4 – Update

 
Lead CI - Chris Thompson

Over the past few months we have been working with stakeholders to integrate research findings into catchment action plans, write up research findings for international journal publications and continue research into developing a river-floodplain evolution model for the Lockyer to use to explore potential trajectories of change under future climate change projections.  The development of the river-floodplain evolution model draws upon our growing knowledge of the key geomorphic processes operating within the Lockyer, and the applicable spatial and temporal scales of these processes. For example, below is an excerpt from a paper to CATENA journal which describes the contemporary processes believed to be operating along the lower Lockyer that is maintaining relatively stable macrochannel morphology.

A channel evolution model for subtropical macrochannel systems
A channel evolution model (CEM) represents stages of channel development in response to specific types of disturbance. In recent years, classic incised/disturbed CEMs have provided process-based understanding of channel adjustment and formed the cornerstone for river restoration and rehabilitation. However, these models cannot be assumed to be universally applicable. A new CEM is proposed for the hydrologically variable subtropical systems (Fig 1). The macrochannel CEM illustrates a cyclical pattern of erosion by channel bank wetflow mass failure followed by re-aggradation by sediment deposition contributing to bank rebuilding.
 
Figure 1. Macrochannel CEM. Stage I represents the relatively large (macro)channel with bankfull capacity >10 year ARI. Broad up arrows indicate aggrading channel banks which have a convex or compound profile if benches are present. Double-headed arrows in channel represent flow regime over the annual to decade scale. Stage II occurs once some upper limit of bank aggradation is achieved. Activation of BMFs requires long duration overbank events. No failed blocks remain due to type of failure and a concave bank profile results. The concave profile creates new sediment accommodation space and a low energy flow zone due to low flow width expansion. Stage III represents the start of deposition in the new accommodation space by subsequent floods. Stage IV represents continued sediment aggradation within the channel on banks and benches with increasing riparian vegetation increasing sediment trapping and shear strength. The bank profile evolves from concave back towards compound and convex shape.
The new CEM has implications for river management and understanding of flood resilience. The default for instream works in many river systems is stability rather than dynamic equilibrium. A current river management approach in subtropical Eastern Australia is to apply engineering solutions such as bank toe protection with engineered log jams and bank re-shaping to return the channel to pre-flood form based on assumptions of channel change trajectories derived from the classic CEM.Proactive approaches to river management allow natural recovery processes to proceed, enhancing where possible the rate at which they occur. The macrochannel CEM provides the necessary understanding required to adequately determine the current stage of adjustment of a river reach (e.g. Figure 2) and determine whether 1) intervention is necessary, or whether the system should be left to adjust and recovery naturally, 2) if intervention is necessary whether it will be successful. The wrong intervention at the wrong stage of the CEM could induce secondary consequences that amplify process response and exacerbate threatening processes rather than ameliorate them. The proposed CEM, on-the-other-hand, indicates that within-macrochannel adjustment is self- modulating and it is possible for the system to naturally return to a previous state without the need for expensive engineering solutions. However, if accelerated sediment storage via bench and bank aggradation is a desired management outcome, then the proposed macrochannel CEM suggests that it may be most beneficial to intervene when a reach is at Stage III-IV once the system has switched from degradation back to aggradation. For example, this would encourage selected management actions that can accelerate the process of vegetation recovery to increase boundary resistance and sediment trapping efficiency. There are a number of examples of pre-existing failure scars upon which native vegetation has established and maintained bench development while surrounding banks failed (82% of pre-existing BMF have not re-failed).  Reaches that are currently at Stage II may be best left to adjust towards Stages III and IV before intervention.
Figure 2. Preliminary classification of macrochannel CEM Stages along Lockyer Creek. Grey line upstream of Helidon represents bedrock channel upstream of the Quaternary alluvium.
 

PhD Updates 

Daryl Lam - PhD Update

  
The last few months have been spent doing a lot of statistical and programming work to improve our understanding of extreme flood events in the region. Using the space-for-time concept, and applying a fairly new concept of Probabilistic Regional Envelope Curve (PREC), I have integrated regional records of extreme flood events into existing gauging sites records. The primary aim is to improve at-site Flood Frequency Analysis (FFA) for the region. One of the key findings is the comparison between the FFA and the new PREC-FFA is that the degree of difference in probability 100 year ARI reduces when a gauging station has >50 years of records and all the stations with over 55 years of Annual Maximum Series records has than 10% (Figure 1). It is generally accepted that short gauging records, and often without big events recorded, render the inaccuracy of FFA for large design floods (ARI >100 years), but often, they do not specify what is the minimum length of records required. As such, this result has significant implications to landuse planning and policy as well as dam constructions and upgrades.
 
In addition, another round of fieldwork is currently underway, more extreme flood deposits have been collected in the Mary catchment and more will be collected in the Logan-Albert over the next few weeks. Once that is completed, the focus for the next couple of months will be preparing the document and presentation for the mid-candidature review of my PhD in November. 
The graph compares the 100 Year Average Recurrence Interval (ARI) traditional FFA and the new PREC-FFA. The results indicate that all the stations with > 55 years record show an error margin of less than 10% between the FFA.

Peyton Lisenby - PhD update

 
PhD-level research in Stage 3 is currently focused on evaluating how effective storm events and geomorphologic adjustments are in moving sediment and instigating changes throughout the catchment. This work will build upon earlier work by Fryirs, Lisenby and Croke, on the morphological resilience of Lockyer Creek, and by Lisenby and Fryirs on channel adjustments within distinct tributary systems of the Lockyer Valley. A literature review paper discussing the history and applications of geomorphic effectiveness concepts is currently in preparation in order to establish a context for further analysis in the Lockyer Valley. Critical to this investigation will be a characterisation of the spatiotemporal connectivity between hillslopes, tributaries and trunk streams. Initial data collection supporting connectivity analysis has already begun and will continue through the end of 2015.

Heather Haines – PhD Update


This past quarter saw me travelling around quite a bit in relation to several aspects of my PhD program.  In early June I travelled to Maine to attend North American Dendroecological Fieldweek which is a 10 day training program covering all aspects of dendro research.  Groups of 4-10 are formed around different topics and then an entire field and lab project is undertaken by each group during the 10 days with a report and presentation completed on the final day.  Each year a PhD student from each group is selected as a NADEF Research Fellow to continue the work started at NADEF by leading the write-up of a peer reviewed publication and by attending a national/international conference to present the results.  I am excited to announce that I was chosen as the NADEF Research Fellow for my project and have been awarded $3000 to use towards travel to the Ameridendro conference early next year in Mendoza, Argentina.  While there I will present both on the NADEF project but also on my PhD research which will be a benefit to my work as many South America dendrochronologists work with tree species similar to those in tropical/subtropical Australia.
 
In July I presented on my PhD research at the INQUA 2015 Congress in Nagoya, Japan.  I really enjoyed the opportunity to attend such a large international conference.  I met a lot of Australian and International Scientists and had a chance to discuss both my research and the research going on around the world that would tie in well with my PhD.  My presentation on my Lamington chronology was well received and I had some good feedback from members of the audience. 
 
Along with travelling, some writing and lab work had also been completed.  The Lamington chronology is coming together and the results from my April/May work at ANSTO are being used to tie all the tree level records together.  I have continued the work on the rainfall paper with an intention to have it ready for publication within the next month.  I also recently completed my mid-candidature review milestone.
 
Over the next quarter I intend to put a heavy emphasis on labwork to move my project forward.  I will again be travelling to ANSTO for 3½ weeks in October as part of my AINSE PGRA grant where I will work on analysis of trees from both my Lamington and D’Aguilar sites.  I will also spend two weeks working with Dr Nathan English in Cairns/Townsville in November undertaking fieldwork as part of my Wet Tropics Management Authority 2015 Research Grant.
 
Heather Haines coring a Pinus banksiana (Jack Pine) tree in Acadia National Park as part of the NADEF 2015 field program.

James Daley – PhD Update


I have recently completed my mid-candidature review of my PhD and have submitted a manuscript to Earth Surface Processes and forms for academic review. Both of these are major milestones of my PhD. The paper focused on the mid-reaches of the Lockyer Creek between Lockyer Sidings and Grantham, in an attempt to understand the significant downstream variation in channel capacity. The results of this work indicate that inherited controls from earlier phases of valley evolution have been fundamental to the formation and maintenance of the macrochannel. The underlying bedrock topography and resistant basal alluvium associated with earlier episodes of valley accretion strongly influence the present channel morphology.  Channel incision and the formation of the macrochannel occurred approximately 10,000 years ago as the river incised into a pre-existing bedrock valley. Bedrock and older alluvium in the banks of the macrochannel limit lateral adjustment and the variable spatial distribution of these resistant features underlying the terrace alluvium has resulted in highly variable macrochannel widths.
The influence of bedrock topography can be seen as exposures along the banks and beneath the terrace at some locations through this reach, with a 6-7m slot cut into a planated bedrock surface. Evidence of this incision is preserved along the Lockyer Creek and several tributaries which feature cascades of the same height. Although we have not been able to determine when this bedrock incision occurred, the preservation of material dating back 230,000 years provides a minimum age of the event. Pre- and post- flood analysis of elevation across these cascades suggests they did not significantly migrate (or further incise) during recent major floods.  Further work will involve placing this case-study based understanding into a broader picture of macrochannel formation and river evolution in SEQ.
 A panorama of the Helidon terraces expansion reach, with extensive floodplains that have formed throughout the mid to late Holocene.
A cascade along Monkey Waterholes Creek preserves evidence of a 6-7m bedrock incision event. The bedrock is now coated with a deposit of travertine that has mineralised from the ‘soda spring’ waters that feed the creek.

Jack Coates-Marnane - PhD Update


At this stage my major focus is writing and finalising some lab work that will contribute to latter publications. Earlier this month, John Tibby and Deborah Haines from the University of Adelaide visited our group to discuss the ongoing work as part of my PhD. This was an exciting meeting as now we are at the final stages of building a palaeoclimate record for SEQ based on the Moreton Bay sediment cores.  In November this year I will be travelling to New Zealand for the Australian Society of limnology and New Zealand Freshwater sciences society’s joint conference in Wellington. I will be discussing the significance of the 2011 and 2013 floods for South East Queensland and leaning more about problems facing catchments and water resources in New Zealand. 

Jack Coates-Marnane - PhD Update


At this stage my major focus is writing and finalising some lab work that will contribute to latter publications. Earlier this month, John Tibby and Deborah Haines from the University of Adelaide visited our group to discuss the ongoing work as part of my PhD. This was an exciting meeting as now we are at the final stages of building a palaeoclimate record for SEQ based on the Moreton Bay sediment cores.  In November this year I will be travelling to New Zealand for the Australian Society of limnology and New Zealand Freshwater sciences society’s joint conference in Wellington. I will be discussing the significance of the 2011 and 2013 floods for South East Queensland and leaning more about problems facing catchments and water resources in New Zealand. 

International students join the team....
meet Pim van den Berg and Robert Valkenburg

My name is Robert Valkenburg and I am studying International Land and Water Management at the Wageningen University in the Netherlands. During my internship at the University of Queensland from September until December,  I will research my BSc Thesis to be written up next year. I will investigate the impact of tributaries and weirs on the bed sediment and grain size in the Lockyer Creek. The aim of the project is to characterise the inputs from tributaries and compare them with the channel bed sediment in the Lockyer Creek. To do this I will take samples from the channel bed to determine the mean sediment and compare this with channel bed samples taken in the tributaries. I will also take channel bed samples just before the weirs and just before a tributary enters the Lockyer Creek. The samples will be analysed using a sediment dry sieve and a mastersizer laser scanner for sediment particles smaller than 2mm. Digital Elevation Models (DEMs) in ArcGIS will also be used to determine the height of the land and possible loss of soil.  A M9 River profiler will be used for depth measurements underwater.
My name is Pim van den Berg and I am also studying International Land and Water Management at Wageningen University in the Netherlands. During my four month internship at the University of Queensland I will investigate sediment trapping efficiency of weirs in the Lockyer valley.
 
The 2011 and 2013 floods eroded and transported a lot of sediment. Weirs decrease the energy slope of a creek and therefore promote sediment deposition. I will investigate the channel bed and sedimentology of the weir pool to assess the extent pf sediment deposition. I will start by analysing the existing Digital Elevation Models, channel long profiles, air photos, and if available, existing bathymetric survey data. Then I will do a bathymetric survey of two weir pools to fill in data gaps and/or compare with existing data. I will also evaluate the extent of sedimentology by taking samples along channel centre. This can potentially be used to determine the time of deposition.​
 

Publications


Baggs Sargood, M. 2013. Hitting rock bottom: Morphological response of upland bedrock-confined streams to catastrophic flooding, BEnvSc Hons, School of Earth & Environmental Science, University of Wollongong.

Baggs-Sargood, M., Cohen, T.J., Thompson, C.J., Croke, J. 2015. Hitting rock bottom: morphological responses of bedrock-confined streams to a catastrophic flood, Earth Surface Dynamics 3, 1-15, 2015. DOI 10.5194/esurf-3-1-2015.

Croke, J., Fryirs, K., Thompson, C. 2013. Channel-floodplain connectivity during an extreme flood event: Implications for sediment erosion, deposition, and delivery, Earth Surface Processes and Landforms 38 (12): 1444-1456.

Croke, J., Reinfelds, I., Thompson, C., Roper, E. 2013. Macrochannels and their significance for flood-risk minimisation: examples from southeast Queensland and New South Wales, Australia, Stochastic Environmental Research and Risk Assessment: 1-14.

Croke, J., Todd, P., Thompson, C., Watson, F., Denham, R. Khanal, G. 2013. The use of multi temporal LiDAR to assess basin-scale erosion and deposition following the catastrophic January 2011 Lockyer flood, SE Queensland, Australia, Geomorphology 184: 111-126.

Croke, J., Denham, R., Thompson, C., and Grove, J. 2014 Evidence for self-organised criticality (SOC) in river bank mass failures; a matter of perspective? Earth Surface Processes and Landforms. DOI: 10.1002/esp.3688 

Fryirs, K., Lisenby, P. and Croke, J. 2015. Geomorphic responses to a catastrophic flood in a resilient river system: Historical context for the 2011 Lockyer Valley floods. Geomorphology.241, 55-71. doi:10.1016/j.geomorph.2015.04.008

Fryirs, K., Lisenby P.E., Croke, J. 2015. Morphological and historical resilience to catastrophic flooding: The case of Lockyer Creek, SE Queensland, Australia. Geomorphology 241, 55-71.

Grove, J., Croke, J. and Thompson, C. 2013. Quantifying different riverbank erosion processes during an extreme flood event, Earth Surface Processes and Landforms 38 (12): 1393-1406.

Grove J.R., Croke J., Thompson C.J. 2014. Making a difference: examples of the use of repeat LiDAR datasets to guide river management decisions following extreme floods, in Vietz, G; Rutherfurd, I.D, and Hughes, R. (editors), Proceedings of the 7th Australian Stream Management Conference, Townsville, Queensland, pp 109-115. 

Smith, B. 2013. The role of vegetation in catastrophic floods: A spatial analysis, BEnvSc Hons, School of Earth & Environmental Science, University of Wollongong.

Thompson, C., and Croke, J. 2013. Geomorphic effects, flood power, and channel competence of a catastrophic flood in confined and unconfined reaches of the upper Lockyer valley, southeast Queensland, Australia, Geomorphology 197: 156-169.

Thompson, C., Croke, J., Grove, J., Khanal, G. 2013. Spatio-temporal changes in river bank mass failures in the Lockyer Valley, Queensland, Australia, Geomorphology 191: 129-141.

Thompson C., Croke, J., Dent, C. 2014. Potential impacts of levee construction in the Lockyer Valley, in Vietz, G; Rutherfurd, I.D, and Hughes, R. (editors), Proceedings of the 7th Australian Stream Management Conference, Townsville, Queensland, pp 109-115. 

Thompson, C., Fryirs, K., and Croke, J. 2015. The disconnected conveyor belt: Patterns of longitudinal and lateral erosion and deposition during a catastrophic flood in the Lockyer Valley, southeast Queensland, Australia. River Research and Application, DOI: 10.1002/rra.2897.
 

Submitted/ In Review

Daley, J., Croke, J., Thompson, C., Cohen, T., Macklin, M., Sharma, A. (in review) Between a rock and a hard bank: the nature, timing and controls on macrochannel formation in subtropical Australia, Earth Surface Processes and Landforms.

Croke, J., Thompson, C., Daley, J., Fryirs, K., Lisenby, P., Lam, D., Dalla Pozza, R., Grove, J. and Cohen, T. (accepted). Defining the floodplain in hydrologically-variable settings: Implications for flood magnitude-frequency analysis and interpretations of landscape resilience. Earth Surface Processes and Landforms Special Issue.

Kemp, J., Olley, J., Ellison, T., McMahon, J.  Submitted. Agriculture, floods and channel change in a subtropical catchment: the Brisbane River, Australia.  Anthropocene.    

Haines, H.A., and Olley, J.M. Submitted.  A review of dendroclimatology in Australia. Quaternary Science Reviews.
 
Thompson, C. J., Croke, J., Fryirs, K., and Grove, J. (accepted). A channel evolution model for non-incising, macrochannel systems. Catena.

Lisenby, P.E., Fryirs, K. Under review. Catchment- and reach-scale controls on the expectation of geomorphic channel adjustment. Water Resources Research.

 
Conference Papers
 
Haines, H.A., English, N., Olley, J.M., Hua, Q., Heijnis, H., Gadd, P., and Palmer, J. “Identifying flood and drought events using a 500-year reconstruction of rainfall in the Australian subtropics as determined from Hoop Pine (Araucaria cunninghamii) tree rings.”  19th International Union for Quaternary Research (INQUA) Congress, Nagoya, Japan, July 26th – August 2nd, 2015.

Thompson, C.J. 2015. Understanding the geomorphic system for floodplain hazard awareness, lessons from the Lockyer. Floodplain Management Association National Conference, 19-22 May 2015, Brisbane.
 

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