Dr Tim Cohen
Position: Senior Lecturer
Phone: +61 2 4239 2375
As a geomorphologist my interests lie in landscapes and landform evolution. In many ways my research encompasses natural history, earth science, climatology and resource management. I have had extensive experience in both the research and applied aspects of environmental science working for state governments, resource management agencies and as an independent consultant.
- Fluvial geomorphology
- Arid zone geomorphology
- Palaeoclimatology and Quaternary studies
- River and catchment management
Current Research Projects
Central Australian Palaeoclimatology
In 2009 I was awarded (with colleagues from the University of Wollongong – Gerald Nanson, Brain Jones and Colin Murray-Wallace) an ARC Discovery Project “How green were our deserts? Evidence for Late Quaternary climate change and the source of water in the Lake Eyre basin”
This project aims to determine the timing of large lake-filling events in Lake mega-Eyre and Lake mega-Frome identifying the duration of such events, the climate at the time and ultimately the source of the water. This project involves geochronology of past lake deposits (shorelines and lake floor sediments) using optically stimulated and thermally stimulated luminescence (OSL and TL), amino acid racemisation and stable isotopes on freshwater molluscs, and uranium series dating on arid-zone cave deposits with Dr Pauline Treble (ASNTO). It also includes the use of cosmogenic nuclide analysis on bedrock channels with collaborators Dr John Jansen (Stockholm University) and Dr Derek Fabel (University of Glasgow). Other collaborative and related work is being undertaken on the alluvial fans of the Flinders Ranges (Dr Jan Hendrik May).
Late Quaternary fluvial chrono-stratigraphy
My research into fluvial archives focuses on the last glacial cycle and investigates the preservation and climatic significance of alluvial deposits along the eastern seaboard. Such research utilises (OSL) and in 2011 I was awarded an ARC Discovery Project with Professor Shulmeister (University of Queensland), Dr Kevin Kiernan (University of Tasmania), Dr Craig Woodward (University of Queensland), Dr Tim Barrows (Exeter University), Dr Justine Kemp (University of Northumbria), Dr Kat Fitsimmons (Max Planck Institute), and Associate Professor Doug Clark (Western Washington University). This project focuses on the last glaciation maximum climate conundrum and environmental responses of the Australian continent.
Predicted impacts of 21st century sea-level rise on rivers
Identifying how and where predicted sea level rise will impact the catchments of eastern Australia is an area of expanding research of mine. Using the Holocene hightstand (the last time sea levels were as high as they are predicted to be in the 21st century) as an analogue we are assessing how significantly the riverine landscape was affected by the last sea level rise.
Post-European channel dynamics and river rehabilitation
I have ongoing projects assessing the nature and timing of how river systems in south-eastern Australia responded to the arrival of Europeans. Understanding this is critical to prescribing effective rehabilitation management plans and I have been involved in numerous projects assessing the effectiveness of various remedial works in gravel bed rivers.
I currently teach both undergraduate and postgraduate courses including:
- EESC303 Fluvial geomorphology and sedimentology
- ENVI 923 Environmental Planning
- ENVI 922 Scientific basis of environmental management
Service and Outreach
I play a role in contributing to professional organizations within the field of geomorphology and Quaternary Science. I am currently the Australian New Zealand Geomorphology Group (ANZGG) secretary and co-convened the 13th ANZGG 2008 conference in Tasmania. I am also currently the OZ-INTIMATE co-convenor (INTIMATE - INTegration of Ice core, Marine and Terrestrial Records). This is a major international palaeoclimate project sponsored by INQUA aimed at reconstructing climates in Australia/New Zealand and the Southern Ocean over the last 30,000 years. OZ-INTIMATE is the Australian component of the AUS-INTIMATE INQUA sub-group and I co-convened the OZ-INTIMATE meeting Dec-2010.
1. Cohen, T.J., Nanson, G.C., Jansen, J.D., Jones B.G., Jacobs, Z., Larsen, J.R., May, J-H., Treble, P., Price, D.M., Smith, A.M., (2011). Late Quaternary mega-lakes fed by the northern and southern river systems of central Australia: varying moisture sources and increased continental aridity. Palaeogeography, Palaeoclimatology, Palaeoecology (in press, accepted April 2011).
2. Cohen, T.J., Nanson, G.C., Jansen, J.D., Jones B.G., Jacobs, Z., Treble, P., Price, D.M., May, J-M., Smith, A.M., Ayliffe, L.K., Hellstrom, J.C. (2011). Continental aridification and the vanishing of Australia's megalakes. Geology 39 (2), 167-170. Toll-free link: http://geology.geoscienceworld.org/cgi/content/full/39/2/167?ijkey=GUz71rBfSeG8s&keytype=ref&siteid=gsgeology
3. Cohen, T.J., Nanson, G.C., Larsen, J.R., Jones, B.G., Price, D.M., Coleman, M., and Pietsch, T.J., (2010). Late Quaternary aeolian and fluvial interactions on the Cooper Creek Fan and the association between linear and source-bordering dunes, Strzelecki Desert, Australia. Quaternary Science Reviews 29, 455-471.
4. Nanson, G.C., and Price, D.M., Jones, B.G., Maroulis, J.C., Coleman, M., Bowman, H., Cohen, T.J., and Pietsch, T. (2008). Alluvial evidence for major flow-regime changes during the Middle and Late Quaternary in eastern central Australia. Geomorphology, 101, 109-129.
5. Cohen, T.J and Nanson, G.C. (2008). Topographically associated but chronologically disjunct late Quaternary floodplains and terraces in a partly confined valley, southeastern Australia. Earth Surface Processes and Landforms. 33, 3, 424-443. doi:10.1002/esp.1565.
6. Cohen, T. J. and Nanson, G. C. (2007) Mind the gap: an absence of valley fill deposits identifying the Holocene hypsithermal period of enhanced flow regime in southeastern Australia. The Holocene, 17, 411-418.
7. Reinfelds, I., Cohen, T. J., Batten, P., and Brierley, G. (2004) Assessment of downstream trends in channel gradient, total and specific stream power: a GIS approach. Geomorphology, 60, 403-416.
8. Nanson, G. C., Cohen, T. J., Doyle, C. J., and Price, D. M. (2003) Alluvial evidence of major late-Quaternary climate and flow-regime changes on the coastal rivers of New South Wales, Australia. In: K. Gregory and G. Benito (Editors), Palaeohydrology: Understanding Global Change. Wiley, Chichester, pp. 233-258.
9. Cohen, T. J., and Brierley, G. J. (2000) Channel instability in a forested catchment. Geomorphology, 32, 109-128.
10. Brierley, G. J., Cohen, T. J., Fryirs, K., and Brooks, A. P. (1999) Post-European changes to the fluvial geomorphology of the Bega catchment, Australia: implication for river ecology. Freshwater Biology, 41, 1-10.
Recent research grants
Nanson, G.C., Jones, B.G., Chivas, A.R., Woodroffe, C.D., Fryirs, K.A., Murray-Wallace, C.V., Dodson, J.R., Cohen, T.J., Harrison, S.P., Nanson, R.A., Williams, M.A., Collins, A.S., Amos,K.J., Hesse, P., Cendón, D.I., Pietsch, T.J., Brooks, A.P., Goodwin, I.D., Olley, J.M. (2011) ARC LIEF LE110100220 Sonic drilling to provide contamination-free core sampling of rock and unconsolidated sediment.
Shulmeister, J., Cohen, T.J., Kiernan, K., Woodward, C., Barrows, T., Kemp., J., Fitzsimmons, K., Clark, D. (2010) ARC Discovery DP110103081 ”The last glaciation maximum climate conundrum and environmental responses of the Australian continent to altered climate states.” A - $360,000
Westaway, K., Goodwin, I., Fryirs, K., Hesse, P., Fanning, P., George, S., Cohen, T.J (2009) Luminescence dating facility – dosimetry and luminescence detection. RIBG – Macquarie University. A - $65,437
Nanson, G.C., Jones, B.J., Murray-Wallace, C.V., Cohen, T.J. (2009) ARC Discovery DP1096911 “How green were our deserts? Evidence for Late Quaternary climate change and the source of water in the Lake Eyre basin.” A - $350,000
Cohen, T.J., Jones, B.J. (2009) AINSE Award (09074) A fluvial record of late Holocene climate change on south coast rivers of New South Wales: implications for predicted sea-level rise. A - $8430
Nanson, G.C., Chivas, A.R., Roberts, R.G., Murray-Wallace, C.V., Head, L., Cohen, T.J. Arnold, L. (2007) Reader for Optically Stimulated Luminescence dating. RIBG – University of Wollongong. A - $60,000
Cohen, T.J., Lawson, A., Miller, S., Blackall, D., Ely, D. (2007) Sea level changes: linking art and science. Partnership Development Grant – University of Wollongong. A - $4030
Tanyalak Sripho (PhD) – Full-time – Rainfall-runoff modelling in the Lake Eyre basin
Kele Mahar BSc (Hons) – Full-time – Fluvial-deltaic transitions on Mullet Creek, Lake Illawarra
- Using sedimentary archives to determine palaeoenvironments of eastern Australia – see advert for PhD – Stipend top-up available
- Managing an incising river with engineered log jams (industry collaboration)
- The effectiveness of river rehabilitation works on the north coast of NSW (industry collaboration)
- Effects of wake-boarding on the Shoalhaven River (industry collaboration)
SEES Student Noticeboard
If you are intending to meet the Faculty of Science math requirement by completing MATH151 please check when it will be offered