Copy
Big Flood Newsletter Issue 4, Feb 2015
View this email in your browser
Issue 4: February, 2015
 
Welcome to our first issue of the ‘Big Flood’ Newsletter for 2015 and hope everyone had a relaxing and peaceful break over Xmas.  The end of 2014 finished with some excellent presentations by the students and project members at the Australia New Zealand Geomorphology Group (ANZGG) at Mt Tamborine.  Heather Haines and Peyton Lisenby were awarded best poster and best new PhD presentation respectively and Daryl Lam was awarded a very worthwhile prize for the most entertaining presentation from a postgraduate.  I think all of the students received very positive feedback on their results and did a great job at representing the project – we even trialled our new Project PowerPoint template (designed by James Daley), which caused quite a stir. The conference was followed by the Geomorphic Change Detection (GCD) workshop run by A/Prof Joe Wheaton from Utah State at the University of Queensland.  This was well attended in the end with both representatives from key Industry partners and many external agencies. Thanks to Chris Thompson and Ramona Dalla Pozza for working through the logistics on this one. Joe was very impressed with the work being undertaken here in Australia and has suggested he would like to return as part of his sabbatical in the next year or so.  I finished the year with a presentation to the Council of the Lockyer Valley outlining the progress and key deliverables of the project and this was well received with a lot of positive interest in the emerging science and products. There are several emerging initiatives such as the River Improvement Trust and implementation of Catchment-specific management plans that the ARC work is currently feeding into and we look forward to contributing the science to underpin some of these important initiatives.

I have been invited to represent the project at a special event in the United Kingdom in May where the Royal Geographical Society, in collaboration with Earth Surface Processes and Landforms (ESPL) and Wiley are hosting a conference on ‘Stormy geomorphology’. This involves a series of targeted presentations by leading experts from around the world on the impact of floods under future climate change predications and importantly what can be done in policy and planning. The event will also produce a special issue of the journal ESPL which will contain amongst many on the topic, an article summarising our work to date here in South East Queensland.

This month we also welcome our first of several Visiting Students from Wageningen University in the Netherlands. Due to collaborations with several key scientist at this institute UQ are sponsoring their visits to undertake a selected piece of research on flood risk or management here in SEQ which will contribute to their Honours degree in the Netherlands. Wout Pulles will be working with Chris in Stage 4 on advancement of some of the levee mapping work that has been presented previously at the Stream management Conference.

Next month, Judy Macklin and Prof Mark Macklin from the Aberystwyth Univeristy, Wales are presenting an art exhibition 'Mythscapes in the Watery Relm' featuring works on floods and floods and the impact these have on people and culture. The opening will be on Friday 20th March at 6 - 8 pm at the Project Gallery, 226 Grey Street, South Bank. All are welcome.

You will note that the format of the Newsletter is also changing to reflect the emergence of more detailed pieces of research within the group. Rather than short updates we plan on producing at least two short communication papers in each edition which will provide some deeper understanding of some of the key concepts and techniques we are using. This Edition Heather and  Peyton  use their recently submitted papers to document the application of dendrochronology to rainfall reconstruction and the historical analysis of channel change in the Lockyer. Justine Kemp and others provide a paper on the history of the Brisbane River.Details of these full appears are provided in our updated publication list.

Stage Leader Updates

Stage 1 – Update

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

Work underway in Stage 1 at the moment involves the analysis of the deep cores extracted from the Lower Lockyer now almost 12 months ago. Annegret Larsen has joined the team for a few months specifically to undertake the sampling and analysis of these cores to produce both an OSL chronology and a reconstruction of pollen and other sedimentological data. We feel very excited about some of the material preserved in these cores and when completed, the results will provide Southeast Queensland (SEQ) with the longest and most detailed record of river response to changing environmental conditions. We anticipate producing several key papers from this work, including a detailed investigation of avulsion which is recognised as a potential, and abrupt, response of the Lockyer to changing conditions. Work is also progressing on completing manuscripts outlining the one-thousand year history of flood deposition in the Lockyer which documents the results of the initial OSL data set from samples collected immediately following the 2011 flood.
 
Dr. Annegret Larsen cutting and sampling cores in the OSL lab which requires working in infared light.

Stage 2 – Update

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

Stage 2 – Establishing a relationship between flood chronologies and climate variability

Data collation for the regional rainfall analysis is progressing. More than 300 rainfall stations across the region had useful daily rainfall records for periods longer than fifty years. These records are currently being analysed to determine the spatial and temporal trends in rainfall across SEQ. Previous analysis of the rainfall records > 100 years in length had shown that there are extended periods of below average and above average rainfall, lasting on average 15 and 6 years respectively. What the current analysis is showing is that the strength and timing of these deviations from average rainfall varies significantly across the region. Once completed the locally specific rainfall records will be correlated with the tree-ring records from Heather Haines study.

Work on the marine cores collected from Moreton Bay continues to proceed at a pace. Dr John Tibby from Adelaide University is collaborating with the Stage 2 researchers, and is examining the distribution of diatoms down the sediment cores. The distribution of the diatoms is expected to be correlated with the size and extent of flood events entering the Bay. This component of the work has been made possible by additional contributions from Department of Science Information Technology and Innovation (DSITI).

Finally we completed a paper examining the response of the Mid Brisbane river channel below the Lockyer to changes in land use and catchment and riparian vegetation clearing. The paper has been submitted to a new journal, Anthropocene, which deals with the influence that human have on the environment. See later in the newsletter for an excerpt from this paper.

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. Work continues processing sediment samples collected from the catchment with the aim of understanding the internal sediment dynamics of the Lockyer catchment. Around 180 samples are currently being processed using x-ray fluorescence. The paper on post-European river change along the Lockyer trunk stream (reported in last newsletter; Fryirs et al.) has just been peer reviewed and we hope that this paper will be accepted in coming months for the journal Geomorphology. The paper on patterns of erosion and deposition and the nature of (dis)connectivity along the Lockyer trunk stream that occurred during the 2011 flood (reported on in last newsletter; Thompson et al.) has been accepted and will appear in the journal River Research and Applications.

Stage 4 – Update

 
Lead CI - Chris Thompson
 
Stage 4 of the ARC Linkage Big flood project is now focussing on developing data layers required for building a river evolution model for the Lockyer using a reduced complexity modelling approach to explore the role of hydrological variability on shaping and maintaining the Lockyer system. Spatial data sets and parameters are being compiled including bedrock boundary grid, rainfall grids, catchment geomorphic units and their characteristic grain size distribution, depth and infiltration capacity, and vegetation cover.  

Stage 4 investigators are participating in a workshop hosted by the DSITI on the 2nd March at the Ecosciences Precinct.   The workshop to scope a potential climate variability research collaboration between DSITI and Antarctic Climate and Ecosystem CRC provides the opportunity to discuss the Big Flood research  with objective of collaboration with other researchers investigating climate/rainfall proxies for SEQ and key policy makers from the Department of Energy and Water Supply and the Department of Environment and Heritage Protection. It is hoped that such links can assist with developing more rigorous rainfall surface grids for input in the river evolution model.

PhD Updates 

James Daley -  PhD Update


An important consideration in understanding channel response to hydrological variability is to determine regionally how streams have and are responding to the climatic conditions within SEQ. Traditionally, less attention has been given to the response of such channels, in contrast to the modes of adjustment in streams with low stream flow variability where inundation is frequent, such as in the Northern Hemisphere. Are the dynamics of Lockyer Creek a unique anomaly or is this a reflection of the broader, regional geomorphic conditions of SEQ rivers. By analysing discharge and geometry data at gauging stations, we can begin to understand the regional trends of SEQ rivers. A characteristic of these streams is a significantly higher discharge capacity than the conventionally-assumed annual mean flood, profoundly affecting channel processes. As is the case in Lockyer Creek, many of these rivers are adjusted to accommodate floods exceeding the 50-year return interval flood (Figure 1). This is certainly relevant to stream management and predicting magnitude-frequency relationships.
 
The next quarter is set to be a busy one, with my mid-candidature review milestone in April and current progress on two publications to be submitted prior to that milestone. The first paper will look at this issue of magnitude and frequency within SEQ rivers, and how this relates to their geometry. I have been looking at what patterns emerge in the channel geometry and how this relates to discharge capacity and flow variability. While working on this, I have also had a large set of OSL dates completed from my field sites between Lockyer Sidings and Grantham, allowing me to begin to understand the long-term evolution of the Lockyer Valley. This will be the primary focus of my second publication.
 
Figure 1: Flood recurrence intervals for selected SEQ streams, with the broken line reflecting the highest recorded flood

Daryl Lam - PhD Update

 
The last quarter went pretty well with the passing of my confirmation seminar in November and a fruitful ANZGG conference in early December. One of the key findings presented at the conference is the relationship between 23 of the most extreme recorded flood events in the region and the Southern Oscillation Index (SOI). It is not surprising to see most of these events take place during La Nina phases, but more interestingly, most of them occur after the switching over from El Nino to La Nina (i.e. during the rising limb, see Figure 1). More detailed analysis is required with synoptic conditions and data. Another findings presented, albeit with a much smaller sample size, is that the 6 most spatially extensive contemporary flood events in the region occurred within the overlapping period of La Nina and the negative phase of the Interdecadal Pacific Oscillation (IPO) (Figure 2). Some studies have shown this period to have favourable conditions for more storms and heavy rainfall. Thus far, these findings based on contemporary records provide the foundations for understanding extreme paleoflood records and their associations with (proxy) climatic records.
 
The main focus of this quarter is fieldwork in at least 2 more field sites and working on developing a national and some regional Hydrological Envelope Curves (EC) for Australia. EC represents an upper bound to the current experience of extreme floods in a given spatial extent. Derived from all maximum systematic (gauged) records, it has largely been used as a good graphical representation/summary of extreme floods. However, I am going to use this as a useful tool to provide a minimum bound to look for extreme paleoflood events greater than those recorded. Unlike many parts of the world, Australia and its sub-regions do not yet have ECs and I intend to produce them shortly.
 

Jack Coates-Marnane – PhD Update


 Over the coming months I will be conducting field work in the lower Brisbane River. I aim to find archives of past flooding events preserved in the wetlands of tributaries entering the Brisbane river estuary. Bulimba creek is a tributary of the Brisbane River and its catchment has remained relatively undisturbed by development in comparison to neighbouring tributaries. The creek’s catchment contains seven freshwater wetlands and areas of significant remnant riparian vegetation. In addition to its ecological significance the sediments of the Bulimba creek wetlands are likely to provide information on the frequency of past flood events in the form of preserved flood deposits. The field work will involve extensive sediment coring with the possibility of using geophysical tools. This component of research will complement my core area of research of using marine sediments in Moreton Bay to gauge historical human impact and flooding frequency in SEQ.

Short Communications

Lamington National Park - subtropical rainforest (H. Haines).

This is an excerpt from a Haines, H., Olley, J., (in prep.) A review of dendroclimatology in Australia. Quaternary Science Reviews which will be submitted for review. As such all copyright is reserved. If you require further details about this material, or wish to reference it, please contact the authors directly for full details.
 

A Brief Review of Dendroclimatology in Tropical and Subtropical Australia  


Haines, H.A., Olley, J.M.
 
1. Introduction
 
Current understanding of long-term climate variability in Australia is severely limited by the lack of available instrumental or historical records, particularly in tropical and subtropical regions.   A few high resolution climate records that start before 1900 exist (Cook et al., 1992), but these are mostly located in the temperate zone.  In North America and Europe climate records have been extended beyond the start of instrumental and historical records by using annually resolved records found in tree rings (Briffa et al., 1990; Cook et al., 2007; Luckman et al., 1997; Wilson & Luckman, 2005).  While dendrochronology (tree-ring dating) is known to be a viable source of environmental data (Brookhouse, 2006), it has not been widely used in Australia.   Australian dendrochronological work began to be implemented regularly in 1974 (Ogden, 1978a) and several subsequent studies have been undertaken that involve some form of tree-ring analytical methods, mostly in the temperate zone.  As part of this ARC project 43 Australia based studies have been reviewed to provide a summary of dendroclimatological work on this continent to date. The review provides a synthesis of current understandings, and suggests directions for future research.  The findings pertinent to the Big Flood Project are summarised here. 
 
2. Previous reviews of Australian dendrochronology
 
Most of the dendrochronological research in Australia has been undertaken in the temperate regions.  This can be largely credited to Ogden (1978a) who indicated that the greatest potential for dendrochronological research in Australia exists within Tasmania, since it possesses several genera of trees that have long-lived individuals and ring-width characteristics that are suitable for crossdating.  In his seminal work Ogden (1978a) identified four pine species as being the most suitable for dendrochronology: Athrotaxis cupressoides (Pencil Pine), Athrotaxis selaginoides (King Billy Pine), Lagarostrobus franklinii (Huon Pine), and Phyllocladus aspleniifolius (Celery-Top Pine).  These species have since been extensively studied (see Ogden, 1978b; Buckley et al, 1997; Allen et al., 2001; 2012; Cook et al, 2006) and climate reconstructions of over 1000 years have been developed.  In the case of Huon Pine a 3592-year temperature record has been developed at Mount Read which is currently the longest Southern Hemisphere tree-ring reconstruction of climate (Cook et al, 2000).  Ogden (1978a) noted in his studies that missing rings and ring wedging are common in many of the Tasmanian Pine samples, causing the ring pattern to be inconsistent around the circumference of a tree.  Additionally, the signals present in some stands appeared to be influenced by local factors that caused some issues when correlating between stands, so site selection was noted to be of high importance.  Through the numerous studies undertaken on these species since the 1970s many of the problems cause by these ring issues have been resolved.
 
Ogden (1978a) also evaluated the potential of several wide ranging mainland tree species.  Unfortunately, the genera most abundant across Australia, Eucalyptus and Acacia, were found to lack clearly defined annual rings, have intrusive ring banding (apparent rings that are not related to environmental variables), lack preserved fossil wood, and are relatively short-lived.  Callitris trees were also evaluated and found to be both widespread and of strong dendrochronological potential but are short lived and plagued by false ring banding (Ogden, 1978a).  However, Ogden (1978a) did indicate that these species grow in many regions where instrumental records are non-existent and therefore they should not be discounted as they may be the only viable source of paleoenvironmental data in these regions.  
 
Ogden (1978a) also briefly reviewed tropical tree species, however, due to the non-seasonal pattern of tree rings in many tropical species Ogden stated that tropical trees have very little use in dendrochronological applications.  Ogden did find however, that annual rings are seen in Araucaria cunninghamii (Hoop Pine), Toona species, and Podocarpus species.  In a subsequent study on the potential of tropical tree species for dendrochronological work, Ogden (1981) noted that coniferous species were more likely to show identifiable ring-banding patterns.  Ogden (1981) states that in some dendroclimatic studies undertaken in the tropical regions of Australia the annual monsoon was observed.  This demonstrated that in tropical regions with an annual wet and dry season, a relationship between the annual pattern of ring-widths and climatic variables can be observed if the right species and variable are selected based on tree phenology and ecology.  Ogden (1981) also explored the use of radiocarbon dating to confirm ring count ages of tropical Araucaria cunninghamii (Hoop Pine) trees.  His results found that even though the rings of this species were poorly defined, the counted age was within error of the radiocarbon date. The follow up review paper allowed Ogden (1981) to suggest that tropical dendrochronology and dendroclimatology was a study worthy of further investigation.
 
Tropical Australian dendrochronology was also discussed by Worbes (2002), who looked at the history and future of this field worldwide.  Worbes (2002) noted that while considerable study had been applied to tropical species, specifically in the past 20-30 years, there were significant knowledge gaps in regards to usable species and environments.  However, numerous overarching observations about tropical dendroclimatology had been developed; most notably that the growth limiting factor in tropical trees is precipitation (Worbes, 2002).  Worbes (2002) states that using newer dating methods, such as radiocarbon dating around bomb peaks, could expand the validity of tree-ring dating in tropical environments.  Worbes (2002) suggests applying alternative multi-technique approaches to develop climate reconstructions and represent past conditions.  Several studies undertaken in Australian tropical and subtropical environments have begun to apply these techniques.
 
3. Dendrochronology in Tropical and Subtropical Australia
 
Tropical dendrochronology is a subfield that has obtained more interest worldwide in the past two decades (Stahle, 1999).  However, compared to temperate zone sites, tropical locations are much more difficult to perform dendroclimatological analysis on.  The majority of tree species in the tropics do not form a distinct annual growth ring and many have issues with false and missing rings (Stahle, 1999; Worbes, 2002).  However, in the late 1970s and early 1980s several tropical species were identified as having both dendrochronological potential as well as a relationship to climatic variables.  Ash undertook a study (1983) utilizing tropical Araucaria cunninghamii (Hoop Pine) and Agathis robusta (Kauri Pine) trees in northern Queensland to determine if they showed annual growth rings and a relationship to climate.  This work determined that rings were identifiable, there was a relationship to rainfall, and the pattern was generally annual in the Hoop Pine samples but more than annual in the Kauri Pine.  Ash (1983) clearly demonstrated that some species of tropical Australian trees were viable sources for dendroclimatic study. 
 
In the subtropical regions of Australia the only species to be studied for dendroclimatic analysis is Toona ciliata (Australian Red Cedar; Heinrich et al., 2009).  Heinrich and Banks (2005) began researching this species at two subtropical sites in NSW using dendrometer bands to understand the seasonality of growth for this species.  Results showed a dormant period in the winter with the majority of growth occurring between early December and late March.  To better understand the wood anatomy structure of Toona ciliata Heinrich and Banks (2006) undertook a study to identify false and missing rings from a subtropical site in Lamington National Park in Southeast Queensland and a tropical site on the Atherton Tablelands in Far North Queensland.  Indistinct ring structures were identified as a feature in these samples causing difficultly in ring boundary identification (Heinrich and Banks, 2006).  A positive relationship to precipitation was found in three crossdated trees from the tropics (Heinrich and Banks, 2006) indicating that this species does form an annual ring that is sensitive to, and therefore useful in reconstructing, climate parameters. 
 
Such detailed analysis on growth-climate interactions permitted the development of the first rainfall reconstruction for an Australian subtropical region (Heinrich et al., 2009).  Twenty dominant and sub-dominant trees in Lamington National Park were utilised to develop a 146-year (1854-2000) subtropical chronology from Toona ciliata trees (Heinrich et al., 2009).  This chronology was then compared to monthly temperature and precipitation data from the Brisbane climate station for the period 1900-2000 and it was determined that rainfall was the highest correlated variable (Heinrich et al., 2009).  This precipitation reconstruction identified five periods of extended drought and four periods of extended wet conditions along with delineating four and six extremely dry and wet years respectively (Heinrich et al., 2009).  As this reconstruction falls entirely within the historical period Heinrich et al. (2009) were able to compare the wet and dry events to historical events presented by Whetton (1997) which showed that actual events were well represented by the reconstruction.
 
4. Implications for the “Big Flood” Dendrochronology Project
 
While subtropical dendrochronology is severely underrepresented in the literature there is great potential for its use in long-term climate reconstruction.  Several tropical/subtropical species have been identified as useful for this type of study, many of which can be found in SEQ.  Two of the longer lived tropical species Araucaria cunninghamii and Araucaria bidwillii are, based on the work of Ogden (1978a) and Ash (1983), viable for creating a rainfall reconstruction that will extend to a length required for this research project.  By applying the same techniques that have been utilized in temperate zone reconstructions, as well as more modern applications as suggested by reviews such as Worbes (2002), a reconstruction should be easily validated.  Dendrochronology is therefore a highly useful application to develop the long-term rainfall reconstruction required to understand the flood and drought history of subtropical SEQ.


5. References
 
Allen, K.J., Cook, E.R., Francey, R.J., Michael, K., 2001.  The climatic response of Phyllocladus aspleniifolius (Labill.) Hook. f in Tasmania.  Journal of Biogeography, 28(3), 305-316.
Allen, K.J., Drew, D.M., Downes, G.M., Evans, R., Baker, P.J., Grose, M., 2012.  Ring width, climate and wood density relationships in two long-lived Tasmanian tree species.  Dendrochronologica, 30, 167-177.
Ash, J., 1983a.  Growth rings in Agathis robusta and Araucaria cunninghamii from Tropical Australia.  Australian Journal of Botany, 31, 269-275.
Briffa, K.R., Bartholin, T.S., Eckstein, D., Jones, P.D., Karlén, W., Schweingruber, F.H., Zetterberg, P., 1990.  A 1,400-year tree-ring record of summer temperatures in Fennoscandia.  Nature, 346, 434-439.
Brookhouse, M., 2006.  Eucalypt dendrochronology: past, present and potential.  Australian Journal of Botany, 54, 435-449.
Buckley, B.M., Cook, E.R., Peterson, M.J., Barbetti, M., 1997.  A changing temperature response with elevation for Lagarostrobos franklinii in Tasmania, Australia.  Climatic Change, 36, 477-498.
Cook, E.R., Bird, T., Peterson, M.J., Barbetti, M., Buckley, B.M., D’Arrigo, R.D., Francey, R.J., 1992.  Climatic change over the last millennium in Tasmania reconstructed from tree-rings.  The Holocene, 2(3), 205-217
Cook, E.R., Buckley, B.M., D’Arrigo, R.D., Peterson, M.J., 2000.  Warm-season temperatures since 1600 BC reconstructed from Tasmanian tree rings and their relationship to large-scale sea surface temperature anomalies.  Climate Dynamics, 16, 79-91.
Cook, E.R., Buckley, B.M., Palmer, J.G., Fenwick, P., Peterson, M.J., Boswijk, G., Fowler, A., 2006.  Millennia-long tree-ring records from Tasmania and New Zealand: a basis for modelling climate variability and forcing, past, present and future.  Journal of Quaternary Science, 21(7), 689-699.
Cook, E.R., Seager, R., Cane, M.A., Stahle, D.W., 2007.  North American drought: Reconstructions, causes, and consequences.  Earth-Science Reviews, 81(1-2), 93-134.
Heinrich, I., Banks, J.C.G., 2005.  Dendroclimatology potential of the Australian red cedar.  Australian Journal of Botany, 53, 21-32.
Heinrich, I., Banks, J.C.G., 2006b.  Variation in phenology, growth, and wood anatomy of Toona sinensis and Toona ciliata in relation to different environmental conditions.  International Journal of Plan Sciences, 167(4), 831-841.
Heinrich, I., Weidner, K., Helle, G., Vos, H., Lindesay, J., Banks, J.C.G., 2009.  Interdecadal modulation of the relationship between ENSO, IPO and precipitation: insights from tree rings in Australia.  Climate Dynamics, 33, 63-73.
Luckman, B.H., Briffa, K.R., Jones, P.D., Schweingruber, F.H., 1997.  Tree-ring based reconstruction of summer temperatures at the Columbia Icefield, Alberta, Canada, AD 1073-1983.  The Holocene, 7(4), 375-389.
Ogden, J., 1978a.  On the dendrochronological potential of Australian trees.  Australian Journal of Ecology, 3, 339-356.
Ogden, J., 1978b.  Investigations of the dendrochronology of the genus Athrotaxis D. Don (taxodiaceae) in Tasmania.  Tree Ring Bulletin, 38, 1-13.
Ogden, J., 1981.  Dendrochronological studies and the determination of tree ages in the Australian tropics.  Journal of Biogeography, 8(5), 405-420.
Stahle, D.W., 1999.  Useful strategies for the development of tropical tree-ring chronologies.  IAWA Journal, 20, 249-253.
Wheeton, P., 1997.  Flood, droughts and the Southern Oscillation connection.  In: Webb E.K. (ed), Windows on meteorology: Australian perspective.  CSIRO Publishing, Melbourne, pp 180-199.
Wilson, R.J.S., Luckman, B.H., 2005.  A 500 year dendroclimatic reconstruction of spring-summer precipitation from the lower Bavarian Forest region, Germany.  International Journal of Climatology, 25(5), 611-630. Cook et al., 2006
Worbes, M., 2002.  One hundred years of tree-ring research in the tropics – a brief history and an outlook to future challenges.  Dendrochronologia, 20(1-2), 217-231.
 

This is an excerpt from a journal article which has been submitted for review. As such all copyright is reserved. If you require further details about this material, or wish to reference it, please contact the authors directly for full details.

Geomorphic Assessment of River Response to Floods and Droughts


Lisenby, P. and Fryirs, K. 
 
An analysis of channel change along Lockyer Creek has revealed that this river is relatively resilient to change and that only localised geomorphic adjustments have occurred over the past century, despite experiencing ‘catastrophic’ flood events. Nearly 200 individual sites experienced adjustment between the late 1890’s and 2011. This constitutes only 26% of the trunk stream channel length. The macrochannel has not experienced a significant change in width or position post-European colonisation. We hypothesize that the macrochannel was in place prior to European colonisation and most geomorphic adjustment has occurred within this channel. The majority of the noted changes within the macrochannel affected less than 3% of the channel length (unit removal /erosion/accretion, meander bend extension, chute cutoffs, channel incision/scour, and inset channel realignment), while a few affected greater than 5% (channel widening, bank failure, and unit formation), and only one affected greater than 10% (changes to the geomorphic unit assemblage – 10.3%) (Fryirs et al., under review).
 
One type of geomorphic unit assemblage change involves portions of the channel transitioning from segments of alternating lateral bars to segments of parallel benches bounding either side of the channel (Figure 1). This change from transient sediment storage features to more permanent ones was noted as a general trend in Lockyer Creek. This implies that a gradual shift in the sedimentological regime, or balance of erosion and deposition has occurred in the channel over time, and may be related to observable increases in channel vegetation. The formation or removal of these benches can result in adjustments to the geometry and position of the inset channel. They also serve as inset floodplains within the macrochannel, dissipating flow and storing sediment. In the geomorphic literature, benches were originally and are still commonly referred to as ‘inset floodplains.’ Because they are more permanent features than lateral bars, benches allow for vegetation and seed banks to be better established within the macrochannel, and can contribute significantly to channel roughness (Figure 2) (Thompson et al., 2014).
 
Over the time period studied, the range of geomorphic units increased within the macrochannel. Many of these units were highly transient features associated with the large floods in 1974 and 2011, such as diagonal bars, longitudinal bars, scour pools, and in-channel sand sheets (Fryirs et al., under review). These adjustments have been the most significant of all forms of geomorphic adjustment noted in this system. 
 
References:
Thompson, C., Fryirs, K., Croke, J., in press. The disconnected sediment conveyor belt: Patterns of longitudinal and lateral erosion and deposition during a catastrophic flood in the Lockyer Valley, southeast Queensland, Australia. River Research and Applications.
 
Fryirs, K., Lisenby, P.E., Croke, J., Under Review. Antecedence as a 'geomorphic setting agent' producing contemporary river resilience to catastrophic flooding: the case of Lockyer Creek, SE Queensland, Australia. Geomorphology.
 
Figure 1. Shift from lateral bars to benches on Lockyer Creek near Grantham from 1933 to 1997. Note the presence of banks failures in 2011.
Figure 2. Macrochannel form of Lockyer Creek near Helidon, 2014. Note the established vegetation on the benches after all vegetation was stripped from this area in 2011.  
The middle Brisbane River in 1884 (John Oxley Library).

This is an excerpt from Kemp, J., Olley, J., Ellison, T., McMahon, J.  Submitted. Agriculture, floods and channel change in a subtropical catchment: the Brisbane River, Australia.  Anthropocene, which will be submitted for review. As such all copyright is reserved. If you require further details about this material, or wish to reference it, please contact the authors directly for full details.

Agriculture, floods and channel change in a subtropical catchment: the Brisbane River, Australia

                                               

Kemp, J., Olley, J., Ellison, T., McMahon, J.

European-style agriculture was introduced to the subtropical catchment of the Brisbane River, Australia, 170 years ago.  This study reconstructs the pre-European form and sediments of the Brisbane River using documentary evidence from early European explorers and pioneers.  Newspaper reports, early maps and surveys, and streamflow records are used to assess changes in channel form and position, bed level, and flow regime.  Anecdotal evidence suggests that, within a decade, forest clearance was followed by the incision of minor tributaries and a shift from perennial to seasonally ephemeral flow in the major channels.  By comparison with temperate rivers, morphological changes were relatively modest and occurred ~40 years after parts of the catchment were cleared.  Rates of channel migration have been low since at least 1885 and bed level has been stable since 1894, although bed incision has occurred within 10 km downstream of the major water supply reservoir.  The extent of riparian forest has declined significantly since European settlement.  Since the 1890s, discrete bank failures and channel widening has increased average channel width by ~18 %.  The Brisbane’s present-day compound channel form and its cut-and-fill floodplain appear to be pre-European adaptations to the variable subtropical runoff, and have proved resilient to changes in flow regime and sediment supply.  These findings have important implications for the management of large, variable river systems in the wet-and-dry tropics.

Industry Partner Profile: Dr Kate Smolders from seqwater

 
Seqwater is a Queensland Government statutory authority responsible for ensuring safe, secure and reliable water supply for almost three million people across SEQ As well as providing essential flood mitigation services, Seqwater also provides irrigation services to around 1000 rural customers in five water supply schemes.

Kate Smolders is the Senior Scientist for Catchments from Seqwater. This role sits within the Policy Strategy Research and Innovation team, and a key responsibility of the role is to collaborate with our research partners and other institutions on various research projects.  These research projects deliver evidence-based knowledge of catchment processes and management for sustainable water supply, to inform Seqwater’s business and regulatory requirements, and improve operational efficiency. Outputs from research projects such as the Big Flood Project will be used directly by business units at seqwater including the Source Protection and Planning Unit, Policy and Strategy, Water Security Program, Operations.  To date, Seqwater has benefited significantly from being an industry partner on the Big Flood Project through new information and understanding of the Lockyer catchment e.g. channel-floodplain connectivity and patterns of sediment movement, assessment of key geomorphic processes over large spatial scales, and the use of LiDAR and other spatial data sets produced by the project to put forward ‘no regrets’ options under the Council of Mayors initiative.

An understanding of the geomorphic processes across different spatial scales and how they relate to each other (i.e. reach to catchment scale processes) in order to predict trajectory of recovery, would help inform Seqwater long-term catchment planning and investment at appropriate scales. General principles of catchment and reach-scale processes could be used as a basic guide for intervention and the level of investment. This might be described as ‘key management implication’ points.  This is also necessary in helping to prioritise on-ground work and management. In addition, any quantified information around the frequency, duration and magnitude of events will assist in the preparedness of the water treatment plant operators, dam operators and catchment water quality teams to respond to different events. 
 

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.

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 

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. in press. The disconnected sediment conveyor belt: Patterns of longitudinal and lateral erosion and deposition during a catastrophic flood in the Lockyer Valley, southeast Queensland, Australia. River Research and Applications.

 

Submitted


Baggs-Sargood, M., Cohen, T., Thompson, C., and Croke, J. Submitted. Hitting rock bottom: morphological responses of bedrock-confined streams to a catastrophic flood. Geological Society of America Bulletin.  
 
Fryirs, K., Lisenby, P. and Croke, J. Submitted. Geomorphic responses to a catastrophic flood in a resilient river system: Historical context for the 2011 Lockyer Valley floods. Geomorphology.
 
Kemp, J., Olley, J., Ellison, T., McMahon, J.  Submitted. Agriculture, floods and channel change in a subtropical catchment: the Brisbane River, Australia.  Anthropocene.      

 

 
Conference papers

These papers were persented at the 16th Australian and New Zealand Geomorphology Group Conference held at Mt Tamborine between 30 November and 3 December, 2014:
  • Coates-Marnane, J., Olley, J., Burton, J., 2014. Establishing new records of Holocene climate and environmental change in Moreton Bay, south east Queensland.
  • Fryirs, K., Thompson, C., and Croke, J. 2014. The disconnected sediment conveyor belt: Patterns of longitudinal and lateral erosion and deposition during a catastrophic flood in the Lockyer Vallaey, south east Queensland, Australia. 
  • Grove, J., Croke, J., and Thompson. C. 2014. Power and dominance: using catchment scaling to predict the rate and processes of riverbank erosion.
  • Haines, H. English, N., Saxton, N., Croke, J., Palmer, J., 2014. 500 yr of rainfall in the Australian subtropics as determined from hoop pine tree-rings.
  • Kemp J, Olley J, Ellison T, McMahon J. 2014 Agriculture, floods and channel change in a subtropical catchment: the Brisbane River, Australia.
  • Lam, D., Thompson, C., and Croke, J. 2014. Establishing Links between climate drivers and extreme flood events in south east Queensland. 
  • Lisenby, P., Fryris K. and Croke, J. 2014. Historical river change in the Lockyer Valley, Queensland: Placing the 2011 flood in context. 
  • Thompson, C., and Croke, J. 2014. Channel adjustment in a subtropical catchment: a conceptual model for Lockyer Creek, south east Queensland.
Copyright © 2014*|ARC LINKAGE (LP120200093) *, All rights reserved.


Our mailing address is:
ramona.dallapozza@dsitia.qld.gov.au
Level 4, Building 35, University of Queensland, Brisbane Q 4072

unsubscribe from this list    update subscription preferences