Marine and Freshwater Research Marine and Freshwater Research Society
Advances in the aquatic sciences

A preliminary typology of Australian tropical rivers and implications for fish community ecology

W. D. Erskine A F , M. J. Saynor B C , L. Erskine D , K. G. Evans B E and D. R. Moliere B

A Centre for Sustainable Use of Coasts and Catchments, School of Applied Sciences, University of Newcastle – Ourimbah Campus, PO Box 127, Ourimbah, NSW 2258, Australia.

B Hydrological and Ecological Processes Group, Environmental Research Institute of the Supervising Scientist, GPO Box 461, Darwin, NT 0801, Australia.

C School of Earth and Geographical Sciences, University of Western Australia, Crawley, WA 6009, Australia.

D School of Geosciences, University of Wollongong, Northfields Avenue, Wollongong, NSW 2522, Australia.

E School of Engineering and Logistics, Charles Darwin University, Darwin, NT 0909, Australia.

F Corresponding author. Email:

Marine and Freshwater Research 56(3) 253-267
Submitted: 4 May 2004  Accepted: 7 March 2005   Published: 3 June 2005


Australian tropical rivers are dependent on highly seasonal rainfall and runoff between November and April. They also transport low sediment and solute loads, except where catchments have been disturbed by mining, grazing and cropping. Aquatic habitats or channel units are the physical template influencing fish communities. Pools provide dry-season refuges for fish and channels provide pathways for movement between refuges when streamflows are re-established. A preliminary geomorphological typology of Australian tropical river reaches (excludes estuaries) is proposed that defines nine distinct river types: (1) bedrock rivers (upland channels and gorges); (2) bedrock-confined rivers; (3) avulsive rivers; (4) meandering rivers (confined meandering, laterally migrating unconfined and laterally stable unconfined); (5) straight rivers; (6) floodouts; (7) island- and ridge-anabranching rivers; (8) co-existent mud-braided and anabranching rivers; and (9) extensive freshwater wetlands and billabongs. Many of these have not been recognised overseas and are unique. Channel units differ greatly between river types and contribute to distinctive fish communities in different river types. As expected, fish diversity decreases upstream because of less diverse habitat and natural barriers to fish movement at steps, falls and turbulent cascades and rapids. Fish kills occur in most years and are caused by several different factors that reduce dissolved oxygen.

Extra keywords: anabranching, avulsion, billabongs, channel units, fish kills, fish migration, floodplain stripping, refuges, river reaches, river types, wetlands.


Anon  (2001). Development of a national river classification system. PPK Environment and Infrastructure Report for the Murray–Darling Basin Commission, Rhodes, Australia.

Arthington A. H.Balcombe S. R.Wilson G. A.Thoms M. C.Marshall J.2005Spatial and temporal variation in fish-assemblage structure in isolated waterholes during the 2001 dry season of an arid-zone floodplain river, Cooper Creek, Australia.Marine and Freshwater Research562535doi:10.1071/MF04111

Baker V. R.Pickup G.1987Flood geomorphology of the Katherine Gorge, Northern Territory, Australia.Geological Society of America Bulletin98635646doi:10.1130/0016-7606(1987)98<635:FGOTKG>2.0.CO;2

Beumer J. P.1980Hydrology and fish diversity of a north Queensland tropical stream.Australian Journal of Ecology5159186

Bishop K. A.1980Fish kills in relation to physical and chemical changes in Magela Creek (East Alligator River system, Northern Territory) at the beginning of the tropical Wet season.Australian Zoologist20485500

Bishop K. A.Baker L. M.Noller B. N.1982Naturally-occurring Ichthyocides and a report on Owenia vernicosa F. Muell. (Family Meliaceae), from the Magela Creek system, Northern Territory.Search13150153

Bishop K. A., Allen S. A., Pollard D. A., and Cook M. G. (1986). Ecological studies on the freshwater fishes of the Alligator Rivers region, Northern Territory. Volume 1: outline of the study, summary, conclusions and recommendations. Supervising Scientist for the Alligator Rivers Region Research Report 4. Australian Government Publishing Service, Canberra.

Bishop K. A., Allen S. A., Pollard D. A., and Cook M. G. (1990). Ecological studies on the freshwater fishes of the Alligator Rivers region, Northern Territory. Volume II: synecology. Supervising Scientist for the Alligator Rivers Region Research Report 4. Australian Government Publishing Service, Canberra.

Bishop K. A.Pidgeon R. W. J.Walden D. J.1995Studies on fish movement dynamics in a tropical floodplain river: Prerequisites for a procedure to monitor the impacts of mining.Australian Journal of Ecology2081107

Bishop K. A., Allen S. A., Pollard D. A., and Cook M. G. (2002). Ecological studies on the freshwater fishes of the Alligator Rivers region, Northern Territory: autecology. Supervising Scientist Report 145. Supervising Scientist, Darwin.

Bisson P. A., and Montgomery D. R. (1996). Valley segments, stream reaches, and channel units. In ‘Methods in Stream Ecology’. (Eds F. R. Hauer and G. A. Lamberti.) pp. 23–52. (Academic Press: San Diego, CA.)

Brennan S., and Gardiner E. (2004). Geomorphic assessment of rivers series: Gulf Basin and Mitchell Catchment. Draft. Natural Resources and Mines, Brisbane.

Brierley G. J.Fryirs K.2000River styles, a geomorphic approach to catchment characterization: implications for river rehabilitation in Bega catchment, New South Wales, Australia.Environmental Management25661679

Brierley G.Fryirs K.Outhet D.Massey C.2002Application of the river styles framework as a basis for river management in New South Wales, Australia.Applied Geography (Sevenoaks, England)2291122doi:10.1016/S0143-6228(01)00016-9

Brown T. E.Morley A. W.Sanderson N. T.Tait R. D.1983Report of a large fish kill resulting from natural acid water conditions in Australia.Journal of Fish Biology22335350

Davis L., Thoms M. C., Fellows C., and Bunn S. (2002). Physical and ecological associations in dryland refugia: waterholes of the Cooper Creek, Australia. In ‘The Structure, Function and Management Implications of Fluvial Sedimentary Systems’. (Eds F. J. Dyer, M. C. Thoms and J. M. Olley.) pp. 77–84. (International Association of Hydrological Sciences: Wallingford, UK.)

Dilshad M.Motha J. A.Peel L. J.1996Surface runoff, soil and nutrient losses from farming system in the Australian semi-arid tropics.Australian Journal of Experimental Agriculture3610031012

Douglas I.1967Man, vegetation and the sediment yields of rivers.Nature215925928

Duggan K. (1988). Mining and erosion in the Alligator Rivers region of northern Australia. Ph.D. Thesis, School of Earth Sciences, Macquarie University, Sydney.

Duggan K. (1994). Erosion and sediment yields in the Kakadu region of northern Australia. In ‘Variability in Stream Erosion and Sediment Transport’. (Eds L. J. Olive, R. J. Loughran and J. A. Kesby.) pp. 373–383. (International Association of Hydrological Sciences: Wallingford, UK.)

East T. J. (1996). Landform evolution. In ‘Landscape and Vegetation Ecology of the Kakadu Region, Northern Australia’. (Eds C. M. Finlayson and I. von Oertzen.) pp. 37–55. (Kluwer: Dordrecht.)

Erskine L. (2002). The relationship between riparian vegetation, bank erosion and channel pattern, Magela Creek, Northern Territory. B.Sc. (Hons.) Thesis, School of Geosciences, University of Wollongong, Wollongong.

Erskine W. D. (1999). Channel morphology. In ‘Geomorphology of the Hawkesbury–Nepean River System. A Review of Landforms, Processes and Management’. (Ed. D. Martens.) pp. 26–48. (Hawkesbury Nepean Catchment Management Trust: Sydney.)

Erskine W. D.2001Geomorphic evaluation of past river rehabilitation works on the Williams River, New South Wales.Ecological Management & Restoration2116128

Erskine W. D. (2005). SW-966 Stream classification. In ‘Water Encyclopedia: Surface and Agricultural Water’. (Eds J. H. Lehr and J. Keeley.) (Wiley: New York.) (In press.)

Erskine W. D., and Saynor M. J. (2000). Assessment of the off-site geomorphic impacts of uranium mining on Magela Creek, Northern Territory, Australia. Supervising Scientist Report 156. Supervising Scientist, Canberra.

Erskine W. D., Saynor M. J., Evans K. G., and Boggs G. S. (2001). Geomorphic Research to determine the off-site impacts of the Jabiluka mine on the Swift Creek (Ngarradj) Catchment, Northern Territory. Supervising Scientist Report 158. Supervising Scientist, Darwin.

Evans K. G.Saynor M. J.Willgoose G. R.1999Changes in hydrology, sediment loss and microtopography of a vegetated mine waste rock dump impacted by fire.Land Degradation and Development10507522doi:10.1002/(SICI)1099-145X(199911/12)10:6<507::AID-LDR341>3.0.CO;2-#

Evans K. G., Moliere D. R., Saynor M. J., Erskine W. D., and Bellio M. G. (2004). Water quality trigger values for suspended mud in the Jabiluka mine receiving catchment, NT, Australia. In ‘Proceedings Pacrim 2004 Congress, Adelaide’. (Eds A. Spry and K. Burt.) pp. 447–452. The Australasian Institute of Mining and Metallurgy, Melbourne.

Faulks F. F. (1998). Daly River catchment. Part1. An assessment of the physical and ecological condition of the Daly River and its major tributaries. Part 2. Accompanying sub-catchment information. Technical Report No. TR 99/10. N.T. Department of Lands, Planning and Environment, Katherine.

Faulks J. J. (2001). Roper River catchment. An assessment of the physical and ecological condition of the Roper River and its major tributaries. Technical Report 36/2001. N.T. Department of Lands, Planning and Environment, Katherine.

Finlayson B. L., and McMahon T. A. (1988). Australia v the world: a comparative analysis of streamflow characteristics. In ‘Fluvial Geomorphology of Australia’. (Ed. R. F. Warner.) pp. 17–40. (Academic Press: Sydney.)

Gibling M. R.Nanson G. C.Maroulis J.1998Anastomosing river sedimentation in the channel country of central Australia.Sedimentology45595619doi:10.1046/J.1365-3091.1998.00163.X

Hart B. T.McGregor R. J.1980Limnological survey of eight billabongs in the Magela Creek catchment, Northern Territory.Australian Journal of Marine and Freshwater Research31611626

Harris J. H., and Gehrke P. C. (Eds) (1997). ‘Fish and Rivers in Stress. The NSW Rivers Survey.’ (NSW Fisheries Office of Conservation and the Cooperative Research Centre for Freshwater Ecology: Sydney.)

Hawkins C. P.Kershner J. L.Bisson P. A.Bryant M. D.Decker L. al.1993A hierarchical approach to classifying stream habitat features.Fisheries186312

Jolly P. (2001). Daly River catchment water balance. Report 10/2002, N.T. Department of Infrastructure Planning and Environment, Natural Resources Division, Palmerston.

Jones B. G.Martin G. R.Senapati N.1993Riverine-tidal interactions in the monsoonal Gilbert River fandelta, northern Australia.Sedimentary Geology83319337doi:10.1016/0037-0738(93)90019-2

Knighton A. D.Nanson G. C.1994Waterholes and their significance in the anastomosing channel system of Cooper Creek, Australia.Geomorphology9311324doi:10.1016/0169-555X(94)90052-3

Knighton A. D.Nanson G. C.2000Waterhole form and process in anastomosing channel system of Cooper Creek, Australia.Geomorphology35101117doi:10.1016/S0169-555X(00)00026-X

Knighton A. D.Mills K.Woodroffe C. D.1991Tidal-creek extension and saltwater intrusion in northern Australia.Geology19831834doi:10.1130/0091-7613(1991)019<0831:TCEASI>2.3.CO;2

Knighton A. D.Woodroffe C. D.Mills K.1992The evolution of tidal creek networks, Mary River, northern Australia.Earth Surface Processes and Landforms17167190

Ladson A. R.Tilleard J. W.1999The Herbert River, Queensland, tropical Australia: Community perception and river management.Australian Geographical Studies37284299

Leopold L. B., and Wolman M. G. (1957). River Channel patterns: braided, meandering and straight. U.S. Geological Survey Professional Paper 282B. US Department of Interior, Washington, DC.

McQuade C. V., Arthur J. T., and Butterworth I. J. (1996). Climate and hydrology. In ‘Landscape and Vegetation Ecology of the Kakadu Region, Northern Australia’. (Eds C. M. Finlayson and I. von Oertzen.) pp. 17-35. (Kluwer Academic Publishers: Dordrecht.)

Maroulis J. C.Nanson G. C.1996Bedload transport of aggregated muddy alluvium from Cooper Creek, central Australia: a flume study.Sedimentology43771790

Melville M. D., and Erskine W. D. (1986). Sediment remobilization and storage by discontinuous gullying in humid southeastern Australia. In ‘Drainage Basin Sediment Delivery’. (Ed. R. F. Hadley.) pp. 277–286. (International Association of Hydrological Sciences: Wallingford.)

Moliere D. R., Evans K. G., Saynor M. J., and Erskine W. D. (2000). Suspended sediment loads in the receiving catchment of the Jabiluka uranium mine site, Northern Territory. In ‘Proceedings Hydro 2000, 3rd International Hydrology and Water Resources Symposium, Interactive Hydrology, Volume 1’. pp. 37–42. (Institution of Engineers Australia: Canberra.)

Moliere D. R., Boggs G. S., Evans K. G., Saynor M. J., and Erskine W. D. (2002). Baseline hydrology characteristics of the Ngarradj catchment, Northern Territory. Supervising Scientist Report 172. Supervising Scientist, Darwin.

Moliere D. R.Evans K. G.Saynor M. J.Erskine W. D.2004Estimation of suspended loads in a seasonal stream in the wet-dry tropics, Northern Territory, Australia.Hydrological Processes18531544

Mulrennan M. E.Woodroffe C. D.1998aHolocene development of the lower Mary River plains, Northern Territory, Australia.The Holocene8565579doi:10.1191/095968398676885724

Mulrennan M. E.Woodroffe C. D.1998bSaltwater intrusion into the coastal plains of the lower Mary River, Northern Territory, Australia.Journal of Environmental Management54169188doi:10.1006/JEMA.1998.0229

Nanson G. C.1986Episodes of vertical accretion and catastrophic stripping: a model of disequilibrium floodplain development.Geological Society of America Bulletin9714671475doi:10.1130/0016-7606(1986)97<1467:EOVAAC>2.0.CO;2

Nanson G. C.Knighton A. D.1996Anabranching rivers: their cause, character and classification.Earth Surface Landforms and Processes21217239doi:10.1002/(SICI)1096-9837(199603)21:3<217::AID-ESP611>3.3.CO;2-L

Nanson G. C.East T. J.Roberts R. G.1993Quaternary stratigraphy, geochronology and evolution of the Magela creek catchment in the monsoon tropics of northern Australia.Sedimentary Geology83277302doi:10.1016/0037-0738(93)90017-Y

Noller B. N. (1983). Physico-chemical aspects of natural fish kills on the Magela Creek system. In ‘Proceedings of the Scientific Workshop on Environmental Protection in the Alligator Rivers Region’. pp. 61.1–61.15. Supervising Scientist for the Alligator Rivers Region, Sydney.

O’Gara F. (1998). ‘Sustainable Farming and Grazing Systems for the Semi-Arid Tropics of the Northern Territory.’ (Northern Territory Museum: Darwin.)

Peterson J. T.Rabeni C. F.2001aEvaluating the physical characteristics of channel units in an Ozark stream.Transactions of the American Fisheries Society130898910doi:10.1577/1548-8659(2001)130<0898:ETPCOC>2.0.CO;2

Peterson J. T.Rabeni C. F.2001bThe relation of fish assemblages to channel units in an Ozark stream.Transactions of the American Fisheries Society130911926doi:10.1577/1548-8659(2001)130<0911:TROFAT>2.0.CO;2

Pidgeon R. (2001). Natural causes of fish kills in Top End waterways. Environmental Research Institute of the Supervising Scientist Note, Darwin.

Roberts R. G. (1991). Sediment budgets and Quaternary history of the Magela Creek catchment, tropical northern Australia. Ph.D. Thesis, Department of Geography, University of Wollongong, Wollongong.

Rosgen D. L.1994A classification of natural rivers.CATENA22169199doi:10.1016/0341-8162(94)90001-9

Rosgen D. L. (1996). ‘Applied River Morphology.’ (Wildland Hydrology: Pagosa Springs, CO.)

Russell-Smith J.1985A record of change: studies of Holocene vegetation history in the South Alligator River region, Northern Territory.Proceedings of Ecological Society of Australia13191202

Sammut J.White I.Melville M. D.1996Acidification of an estuarine tributary in eastern Australia due to drainage of acid sulfate soils.Marine and Freshwater Research47669684

Saynor M. J.Evans K. G.2001Sediment loss from a waste rock dump, ERA Ranger Mine, Northern Australia.Australian Geographical Studies393451

Saynor M. J., Erskine W. D., and Evans K. G. (2003). Bank erosion in the Ngarradj catchment: results of erosion pin measurements between 1998 and 2001. Supervising Scientist Report 176. Supervising Scientist, Darwin.

Saynor M. J.Erskine W. D.Evans K. G.Eliot I.2004aGully initiation and implications for management of scour holes in the vicinity of the Jabiluka mine, Northern Territory, Australia.Geografiska Annaler86191203doi:10.1111/J.0435-3676.2004.00224.X

Saynor M. J., Erskine W. D., and Evans K. G. (2004b). Cross sectional and scour and fill changes in the Ngarradj catchment between 1998 and 2003. Supervising Scientist Report 181. Supervising Scientist, Darwin.

Schumm S. A.Erskine W. D.Tilleard J. W.1996Morphology, hydrology and evolution of the anastomosed Ovens and King Rivers, Victoria, Australia.Geological Society of America Bulletin10812121224doi:10.1130/0016-7606(1996)108<1212:MHAEOT>2.3.CO;2

Schumm S. A.Khan H. R.1971Experimental study of channel patterns.Nature233407409

Story R. (1976). Vegetation of the Alligator Rivers area. CSIRO Land Research Series No. 38, 89–111. (CSIRO, Melbourne, Australia.).

Strahler A. N. (1964). Quantitative geomorphology of drainage basins and channel networks. In ‘Handbook of Applied Hydrology’. (Ed. V. T. Chow.) pp. 4.39–4.76. (McGraw-Hill: New York.)

Tooth S. (1999). Floodouts in central Australia. In ‘Varieties of Fluvial Form’. (Eds A. J. Miller and A. Gupta.) pp. 219–247. (Wiley: Chichester.)

Townsend S. A.1994The occurrence of natural fish kills, and their causes, in the Darwin-Katherine-Jabiru region of northern Australia.Mitt. Internat. Verein. Limnol24197205

Townsend S. A.Boland K. T.Wrigley T. J.1992Factors contributing to a fish kill in the Australian wet/dry tropics.Water Research2610391044

Warner R. F.1997Floodplain stripping: another form of adjustment to secular hydrologic regime change in southeast Australia.CATENA30263282doi:10.1016/S0341-8162(97)00014-3

Wasson R. J. (1992). Modern sedimentation and late Quaternary evolution of the Magela Creek Plain. Supervising Scientist for the Alligator Rivers Region Research Report 6. Australian Government Publishing Service, Canberra.

Wasson R. J., Donnelly T. H., and Murray A. S. (1996). Imports can be dangerous – appropriate approaches to Australian rivers and catchments. In ‘Proceedings of First National Conference on Stream Management in Australia’. (Eds I. Rutherfurd and M. Walker.) pp. 313–319. (Cooperative Research Centre for Catchment Hydrology: Melbourne.)

Webb A. A.Erskine W. D.2005Natural variability in the distribution, loading and induced scour of large wood in sand-bed, forest streams.River Research and Applications21169185

Wende R.Nanson G. C.1998Anabranching rivers: ridge-form alluvial channels in tropical northern Australia.Geomorphology22205224

Whitehouse F. W.1944The natural drainage of some very flat monsoonal lands.The Australian Geographer4183196

Williams A. R.1979Vegetation and stream pattern as indicators of water movement on the Magela floodplain, Northern Territory.Australian Journal of Ecology4239247

Williams M. A. J.1969Prediction of rainsplash erosion in the seasonally wet tropics.Nature222763765

Wohl E. E.1992aGradient irregularity in the Herbert Gorge of northeastern Australia.Earth Surface Processes and Landforms176984

Wohl E. E.1992bBedrock benches and boulder bars: floods in the Burdekin Gorge of Australia.Geological Society of America Bulletin104770778

Woodland D. J., and Ward P. J. (1992). Fish communities in sandy pools of Magela Creek, Alligator Rivers Region. Supervising Scientist for the Alligator Rivers Region Research Report 9. Australian Government Publishing Service, Canberra.

Woodroffe C. D.Chappell J. M. A.Thom B. G.Wallensky E.1989Depositional model of a macrotidal estuary and flood plain, South Alligator River, northern Australia.Sedimentology36737756

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