Macrochannels and their significance for flood-risk minimisation: examples from southeast Queensland and New South Wales, Australia

  • J. Croke
  • I. Reinfelds
  • C. Thompson
  • E. Roper
Original Paper


Understanding the frequency and causes of extreme events is crucial for environmental, social and economic protection and planning. In Australia this was never more apparent than January 2011 when widespread flooding across Queensland, New South Wales (NSW), and Victoria resulted in the loss of human lives and devastating impacts to infrastructure and local economies. However, understanding the interplay between the geomorphology of catchments and their hydrology remains poorly developed in floodplain planning guidelines. This paper seeks to explain spatial patterns of flood inundation in terms of downstream variations in channel morphometry; and to discuss the significance of these findings within the context of improving flood risk avoidance strategies and environmental outcomes for urban streams. A prominent characteristic of streams draining catchments in the Lockyer Valley south east Queensland and the Illawarra region of NSW, for example, are well developed macrochannels that have formed in mid-catchment zones. Detailed hydraulic modeling using HEC-RAS, HEC-GeoRAS and ArcGIS indicates that these macrochannels are scaled to accommodate high magnitude floods by operating as ‘bankfull’ channels during such events. In south east Queensland, locations where macrochannels debouch onto unconfined low gradient floodplains appear especially vulnerable to catastrophic flooding because of the efficient delivery and minimal attenuation of flood peaks generated in headwater catchments. Macrochannels and associated landforms can be clearly distinguished and mapped on fine-scale digital elevation models, offering the opportunity to integrate analyses of fluvial landforms and channel processes into hydraulic modeling studies, and ultimately, flood-risk avoidance strategies. Such an approach has the potential to improve on traditional flood risk avoidance methods that are focused primarily on design-flood heights by enabling the interpretation of hydraulic modeling outputs in the context of fluvial landforms that exert a significant control on flood behaviour.


Macrochannels Flood risk LiDAR DEM Floodplain planning 



The Lockyer project is supported by Queensland’s Department of Science, Information Technology, Innovation and the Arts (DSITIA) as part of the Flood Recovery Project 2011 and an Australian Research Council Linkage Award (LP120200093). Greg Rogencamp (SKM) provided assistance with hydraulic model output used with permission from Lockyer Valley Regional Council (LVRC). Tim Pietsch performed the OSL analyses at Griffith University.


  1. Arcement GJ Jr, Schneider VR (1989) Guide for selecting Manning’s roughness coefficient for natural channels and flood plains. United States Geological Survey Water Supply Paper 2339, DenverGoogle Scholar
  2. Australian Bureau of Statistics (ABS) (2010) Accessed 10 Oct 2012
  3. Bewsher Consulting (2001) Towradgi Creek revised flood study draft report February 2001. Flood study prepared by Bewsher Consulting Pty Ltd for Wollongong City Council, WollongongGoogle Scholar
  4. Brunner GW (2002) HEC-RAS: river analysis system hydraulic reference manual. US Army Corps of Engineers Hydraulic Engineering Center (HEC), DavisGoogle Scholar
  5. Bunn SE, Abal EG, Greenfield PF, Tarte DM (2007) Making the connection between healthy waterways and healthy catchments: south east Queensland, Australia. Water Sci Technol Water Supply 7(2):93–100CrossRefGoogle Scholar
  6. Chow VT (1959) Open-channel hydraulics. McGraw-Hill, New YorkGoogle Scholar
  7. Costa JE (1987) A comparison of the largest rainfall-runoff floods in the United States with those of the Peoples Republic of China. J Hydrol 96:101–115CrossRefGoogle Scholar
  8. DIPNR (2004) Riparian corridor management study covering the Wollongong local government area and Calderwood Valley in the Shellharbour local government area. Department of Infrastructure, Planning and Natural Resources, WollongongGoogle Scholar
  9. Erskine WD (2011) Geomorphic controls on historical channel planform changes on the lower Pages River, Hunter Valley, Australia. Aust Geogr 42:289–307CrossRefGoogle Scholar
  10. Erskine WD, Livingstone EA (1999) In-channel benches: the role of floods in their formation and destruction on bedrock confined rivers. In: Miller AJ, Gupta A (eds) Varieties of fluvial form. John Wiley and Sons, New York, pp 445–475Google Scholar
  11. Erskine WD, Warner RF (1988) Geomorphic effects of alternating flood- and drought-dominated regimes on NSW coastal rivers. In: Warner RF (ed) Fluvial geomorphology of Australia. Academic Press, Sydney, pp 223–242Google Scholar
  12. Erskine WD, Warner RF (1998) Further assessment of flood- and drought-dominated regimes in south-eastern Australia. Aust Geogr 29:257–261CrossRefGoogle Scholar
  13. Evans J, Bewick B (2001) Technical Report 73: The Wollongong flash flood event, 15-19 August 1998. Bureau of Meteorology, AustraliaGoogle Scholar
  14. Finlayson BL, McMahon TA (1988) Australia vs. the world: a comparative analysis of streamflow characteristics. In: Warner RF (ed) Fluvial geomorphology of Australia. Academic Press, New York, pp 17–39Google Scholar
  15. Grootemaat G (2000). Spatial characteristics of high magnitude storms and channel response, Illawarra, NSW. BSc (Hons) thesis, School of Geosciences, University of WollongongGoogle Scholar
  16. Gupta AJ, Kale VS, Rajaguru SN (1999) The Narmada River, India, through space and time. In: Miller AJ, Gupta A (eds) Varieties of fluvial form. John Wiley and Sons, New York, pp 113–143Google Scholar
  17. Heritage GL, Milan DJ, Large ARG, Fuller I (2009) Influence of survey strategy and interpolation model upon DEM quality. Geomorphology 112:334–344CrossRefGoogle Scholar
  18. Hickey JT, Salas JD (1995) Environmental effects of extreme floods. United States-Italy Research Workshop, Perugia, Italy. Accessed 25 Oct 2004
  19. Howard DA, Luzzadder-Beach S, Beach T (2012) Field evidence and hydraulic modeling of a large Holocene jökulhlaup at Jökulsá á Fjöllum channel, Iceland. Geomorphology 147–148:73–85CrossRefGoogle Scholar
  20. Hoyle J, Brooks A, Spencer J (2012) Modelling reach-scale variability in sediment mobility: an approach for within-reach prioritization of river rehabilitation works. River Res Appl 28:609–629CrossRefGoogle Scholar
  21. Institution of Engineers Australia (1998) Australian rainfall and runoff a guide to flood estimation. The Institution of Engineers Australia, BartonGoogle Scholar
  22. Jordan PW (2011) Hydrological advice to commission of inquiry regarding 2010/11 Queensland floods. Toowoomba and Lockyer Valley flash flood events of 10 and 11 January 2011. Sinclair Knight Merz Report, April 2011, p 83Google Scholar
  23. Kiem AS, Franks SW, Kuczera G (2003) Multi-decadal variability of flood risk. Geophys Res Lett 30(2):1035CrossRefGoogle Scholar
  24. Levy JK, Hall J (2005) Advances in flood risk management under uncertainty. Stoch Environ Res Risk Assess 19:375–377CrossRefGoogle Scholar
  25. Nanson GC, Hean D (1985) The West Dapto flood of February 1984: rainfall characteristics and channel changes. Aust Geogr 16:249–258CrossRefGoogle Scholar
  26. Nanson GC, Young RW (1981) Downstream reduction of rural channel size with contrasting urban effects in small coastal streams of southeastern Australia. J Hydrol 52:239–255CrossRefGoogle Scholar
  27. NSW Government (2001) Floodplain management manual: the management of flood liable land. NSW Government January 2001. ISBN 07313 0370 9Google Scholar
  28. Olley JM, Pietsch T, Roberts RG (2004) Optical dating of Holocene sediments from a variety of geomorphic setting using single grains of quartz. Geomorphology 60:337–358CrossRefGoogle Scholar
  29. Pilgrim D (ed) (1998) Australian rainfall and runoff: a guide to flood estimation. The Institution of Engineers, BartonGoogle Scholar
  30. Plate EJ (2002) Flood risk and flood management. J Hydrol 267:2–11CrossRefGoogle Scholar
  31. Reinfelds I, Nanson G (2001) ‘Torrents of terror’: the August 1998 storm and the magnitude, frequency and impact of major floods in the Illawarra Region of New South Wales. Aust Geogr Stud 39:335–352CrossRefGoogle Scholar
  32. Reinfelds I, Nanson G (2004) Aspects of the hydro-geomorphology of Illawarra streams: implications for planning and design of urbanisation landscapes, Lake Illawarra catchment, New South Wales. Wetlands (Australia) 21:220–236Google Scholar
  33. Rogencamp G, Barton J (2012) The Lockyer Creek flood of January 2011: what happened and how should we manage hazard for rare floods. 52nd Annual Floodplain Management Association Conference. Accessed 10 Oct 2012
  34. Roper EL (2004) Integrated GIS and hydraulic modeling of high magnitude floods on Mullet Creek: implications for urban management in the Illawarra region of New South Wales. Unpublished BEnvSci (Hons) thesis, Faculty of Science, University of WollongongGoogle Scholar
  35. Rustomji P, Bennett N, Chiew F (2009) Flood variability east of Australia’s Great Dividing Range. J Hydrol 374:196–208CrossRefGoogle Scholar
  36. SKM (2012) Lockyer Creek flood risk management study, vol 1. Sinclair Knight Merz, BendigoGoogle Scholar
  37. Thompson CJ, Croke J (accepted) The geomorphic effects, flood power and channel competence of a catastrophic flood in confined and unconfined reaches of the Upper Lockyer valley, south east Queensland, Australia. GeomorphologyGoogle Scholar
  38. Warner RF (1997) Floodplain stripping: another form of adjustment to secular hydrologic regime change in Southeast Australia. Catena 30:263–282CrossRefGoogle Scholar
  39. Wollongong City Council (2002) Hewitt’s Creek flood study. Wollongong City Council, Wollongong. ISBN 0713 13453Google Scholar
  40. Yang J, Townsend RD, Daneshfar B (2006) Applying the HEC-RAS model and GIS techniques in river network floodplain delineation. Can J Civil Eng 33:19–28CrossRefGoogle Scholar

Copyright information

© Springer-Verlag Berlin Heidelberg 2013

Authors and Affiliations

  • J. Croke
    • 1
  • I. Reinfelds
    • 2
    • 3
  • C. Thompson
    • 1
    • 4
  • E. Roper
    • 2
  1. 1.Australian Rivers Institute, Griffith UniversityNathanAustralia
  2. 2.School of Earth and Environmental ScienceUniversity of WollongongWollongongAustralia
  3. 3.NSW Office of WaterWollongongAustralia
  4. 4.Centre for Integrated Catchment Assessment and Management (ICAM)Australian National UniversityCanberraAustralia

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