University of Wollongong Research Online University of Wollongong Thesis Collection University of Wollongong Thesis Collections 2011 Aspects of the contemporary and Quaternary hydrology of the Lake Eyre Basin, central Australia Joshua Redder Larsen University of Wollongong Recommended Citation Larsen, Joshua Redder, Aspects of the contemporary and Quaternary hydrology of the Lake Eyre Basin, central Australia, Doctor of Philosophy thesis, School of Earth & Environmental Sciences, University of Wollongong, 2011. http://ro.uow.edu.au/theses/3538 Research Online is the open access institutional repository for the University of Wollongong. For further information contact Manager Repository Services: [email protected]. Aspects of the contemporary and Quaternary hydrology of the Lake Eyre Basin, central Australia Joshua Redder Larsen This thesis is presented as part of the requirements for the award of the Degree of Doctorate of Philosophy From the School of Earth & Environmental Sciences University of Wollongong November 2011 THESIS DECLARATION I, Joshua Redder Larsen, declare that this thesis, submitted in fulfilment for the requirements for the award of the award of Doctor of Philosophy in the School of Earth and Environmental Sciences, University of Wollongong, is wholly my own work unless otherwise acknowledged. This document has not been submitted for qualifications at any other academic institution. The chapters of this thesis constitute papers submitted or published within academic journals, and where co-authors are present remain approximately 80% my own work. I developed the ideas, aims and methods for each chapter, conducted all the analysis, and wrote all the text. Whist this text was subject to the review of my supervisors, co-authors, editors and journal reviewers, in general this only changed the presentation and interpretation of results and not the overall aims, methods, or conclusions. Joshua Larsen Gerald Nanson November 2011 i “Whatever idea I might have had of the character of the country into which we penetrated, I certainly was not prepared for any so singular as that we encountered…” Charles Sturt, Australian explorer (1795 – 1869). ii ABSTRACT The availability of surface water resources is of fundamental concern globally, especially in dryland environments where these resources are particularly vulnerable to over-exploitation. Determining the extent and quality of this water also requires some knowledge about the susceptibility of these resources to change. This thesis aims to improve our understanding of the water balance in dryland environments, in particular within the Lake Eyre Basin (LEB) in central Australia, both in terms of modern processes and the factors that may have resulted in changing hydrological conditions during the Late Quaternary. The dissolved load in the contemporary dryland rivers of the LEB is assessed and indicates that evaporation does not significantly modify the ionic content or solute concentration despite large transmission losses to the surface water budget (~64% of mean annual flow). The source of these solutes is investigated and shows that although rainfall and dust account for the bulk of them, silicate weathering also plays a surprisingly important role. This suggests that dryland environments should also be included estimates of the global silicate-weathering cycle. A comprehensive investigation into the cause and fate of the large catchment transmission losses, and their role in the water budget within the LEB is undertaken. The semi-confined alluvial setting caused by the large mud-dominated multiple channel and floodplain system in many parts of the LEB, and in particular the Channel Country of Cooper Creek, has resulted in at least three distinct shallow groundwater recharge pathways. These control recharge rates, the distribution of freshwater lenses, and the evolution of high groundwater salinities. This highlights the importance of preferential flow in semi-confined alluvial settings, and suggests that where hydrological variability is typically high, such as dryland environments, groundwater recharge is perhaps better considered as a probability of occurrence instead as an average rate. Furthermore, the sum of these probabilities may in turn best account for the observed transmission losses in the water budget. The current hydrology of the LEB is complex, making it difficult to interpret the conditions that prevailed during the dramatic changes in climate and hydrology associated with the Late Quaternary. This aspect of the study investigates runoff iii conditions required to maintain the system of terminal lakes. Strzelecki Creek, a distributary of Cooper Creek originating at Innamincka, has a record of fluvial deposition that broadly matches the fillings of the Lake Mega-Frome system. This confirms the ability of the headwaters of the LEB to deliver runoff to both the Mega- Frome and Eyre terminal lakes at various stages of the Late Quaternary. The magnitude of change required to balance the water and energy budgets implied by the existence of much larger lakes throughout the Late Quaternary in central Australia is quantified. The acute sensitivity of surface water hydrology to small changes in climate within dryland environments is highlighted. The results indicate relatively small changes (~ 27 %) in mean basin rainfall can fully account for the existence and maintenance of the largest recorded lake systems. These results have important implications for the interpretation of Late Quaternary climate changes, the impact of early human arrival on the landscape of the LEB, and the role of climate in the extinction of Australia’s megafauna. Previous assessments have largely overlooked the non-linear relationships and potential feedbacks between hydrology and climate, and this has led to some unlikely proposals for palaeo-environmental change during the Late Quaternary. This work can guide future research that combines data-driven and modelling approaches to the investigation of modern and Late Quaternary water balances, especially in the dryland regions of the world. iv ACKNOWLEDGEMENTS Firstly, and not least because of their enduring patience, the biggest thanks must go to my main supervisors Gerald Nanson and Dioni Cendόn, for persevering with my short attention span, and somewhat delayed writing inspiration. I trust the extended tenure has resulted in a finer vintage than would have otherwise been produced by a more rapid completion, which on last inspection has not yet turned to vinegar. It has truly been an inspirational collaboration, and a course from which I have perhaps learnt how to finally be a scientist. For my equally patient and ever supportive family, I guess this is finally it. So, Dad, Mum, Melinda, Grandma, and Grandad, all of this, is as much yours as it is mine. Although the text itself may not bear the hallmarks of your advice or effort, to have begun in the first place, and most definitely to have reached the end, was only made possible because of it. To all willing and unwilling field participants, who in no order of effort or timing include: Martyn Hazelwood, Tim Grey, Anna Halbeck, Sarah Woodward, Tom Gill, Rebecca Jackson, Luke Morley, and Oscar Garrett. It was also a privilege to work and learn in the field with so many accomplished and capable scientists: John Jansen, Tim Cohen, Jan-Hendrick May, and of course my supervisors, Brian Jones, Gerald Nanson, and Dioni Cendόn. In this regard I must also make special mention and thanks to Brent Peterson, without whose technical expertise, not a single sample would have been yielded from that sordid, dusty, and beautifully brutal landscape. Trevor Whitelaw and SANTOS provided much needed field assistance and logistical support, and the staff from both Moomba and Ballera are also thanked for site access and support. Kidman properties at Nappa Merrie and Innamincka, and also the station owners at Merty Merty and Moolawatana, are gratefully acknowledged for providing access and much needed assistance with vehicles, trailers, and tires. I am grateful to the institutional support provided by the University of Wollongong (UOW) and the Australian Nuclear Science and Technology Organisation (ANSTO), especially for providing matching and top-up scholarships, respectively. Funding from the Australian Research Council and Faculty of Science also supported most of the work. When all samples and hope seemed lost, I thank Paul Carr, Lesley Head, Colin Murray-Wallace, the Dean Will Price for their assistance, and of course Gerald v Nanson, who managed to galvanise a full advance in the face of what surely seemed an inevitable retreat. I am indebted to the jovial and upbeat OSL lab facilities at UOW provided by Bert Roberts and Zenobia Jacobs, and especially the support and training from Terry Lachlan. However, it is to the infinite generosity of the Risø luminescence group, especially Andrew Murray, Jan-Pieter Buylaert, Mayank Jain, and Rezza Sobhati, to which I owe any ability to analyse and interpret some aspect of the black-magic world of OSL. Risø is truly a wonderful place to be. I also thank the various lab staff at ANSTO, especially the radiocarbon lab, for the provision of crucial facilities, and also for accommodating the odd OH&S nightmare. In some misguided twist of fate, I have also begun employment as a post-doctoral researcher prior to the completion of the actual doctorate, which apart from being quite absurd has also been both a blessing and a curse. I thank my new employers at the Water Research Laboratory (University of New South Wales), especially Martin Andersen and Ian Acworth, for their continued patience, and especially for the provision of new research directions which have become endlessly distracting and fascinating. Finally, to my wife, without whom, it is safe to say, this work would have stayed in the back lots of near completed and half thought out ideas, never seeing the full roundness of scientific reason. I would never have had the courage to pick everything up and put it together, to trust in some ability to find something worth saying, or even the need to get up in the morning, without this wonderful woman.