Dr Philip Marren

Senior Lecturer in Physical Geography

I am a physical geographer with a wide range of research interests and expertise but with a particular emphasis on fluvial geomorphology, sedimentology and hydrology. Since completing my PhD in 1999, I have undertaken Postdoctoral research at the University of the Witwatersrand and the University of British Columbia, and worked as a Lecturer in Physical Geography at the University of Melbourne. Over this time I have investigated rivers in Australia, New Zealand, southern Africa, Canada, Iceland and the UK. My research includes work on the role of flooding in forming and modifying river channels and floodplains; the impacts of glacier retreat and catastrophic flooding on rivers in glaciated landscapes; and Quaternary environmental change.


BSc (Hons) in Geology with Geographical Science, University of Luton

MSc in Hydrology for Catchment Management, Imperial College London

PhD in Physical Geography, Keele University

Professional Affiliations




GE4001, GE4004, GE5006, GE5011, GE5013 (Module Leader), GE5014 (Module Leader), GE6017, GE6021, WB501


Impacts of extreme floods and environmental change on proglacial rivers

I have studied the sedimentology and geomorphology of glacial outburst floods since my undergraduate days, which went on to result in my first paper (Russell & Marren, 1998). This work described the flood deposits in the Great Glen, Scotland associated with the drainage of the ‘Glen Roy’ ice-dammed lake during the Younger Dryas – probably the largest flood ever to have occurred on mainland Britain. My PhD went on to investigate the role of meltwater releases of varying discharge in forming glaciofluvial deposits in eastern Scotland during the deglaciation of the last Scottish ice-sheet (see Marren, 2001). During this period I was also part of the large team which studied the impacts of the 1996 jökulhlaup on Skeiðarársandur, Iceland. This resulted in a large number of papers (for example, Russell et al., 2001, 2006; Marren et al., 2002). I am still studying the long-term recovery of the landscape from this flood.

Other work in Iceland described the sedimentology of Holocene glacial outburst flood deposits, with the aim of identifying distinctive criteria for identifying them in the sedimentary record. This included older deposits at Skeiðarársandur (Russell & Marren, 1999; Marren, 2002a), and Kverkjökull (Marren et al., 2009). Papers outlining the way these studies go on to provide criteria for recognising jökulhlaup deposits include Marren (2005) and Marren & Schuh (2009).

More recently, I have been interested in the way proglacial landscapes are responding to glacier retreat. This is especially interesting as the retreat of glaciers, certainly in Iceland, has accelerated significantly since 2000. The changes this retreat produces are both hydrological (short term increases in meltwater) and topographic (formation of newly deglaciated areas, recessional moraines, and proglacial lakes). Often the two effects combine, for instance in the formation of river terraces and changing river channel patterns. Following some early observations (Marren, 2002b), I have studied changes at Skaftafellsjökull, Iceland since my first visit in 1996, and described them in recent papers (Marren & Toomath, 2013, 2014).

Low-energy meandering and anabranching rivers

In 2001 I began a postdoctoral fellowship at the University of the Witwatersrand, South Africa. This change of environment prompted an interest in low-energy rivers associated with extensive floodplain wetlands, largely because of the enthusiasm of my mentor, Professor Spike McCarthy. Most of the research effort was on the Klip River in the Free State, which unusually, over the floodplain wetland reach we studied coarsens from mud-dominated to sand-dominated. This is described in Marren et al. (2006) – we think that a very subtle change in gradient was causing mud to be trapped in on the banks and floodplain in the upstream reach but allowing sand to pass through as bedload. The other striking aspect of this reach of the Klip was its network of palaeochannels, formed by repeated avulsions over the previous 30,000 years. Avulsion here is an autogenic process, driven by cycles of channel formation by ‘incisional’ avulsions followed by decreasing channel efficiency over time, triggering the next avulsion. This work is described in Tooth et al. (2007). Other work from this time was on the Nyl River in the Limpopo Province (e.g. McCarthy et al., 2011).

I continued this work when I moved to the University of Melbourne in 2008, as many Australian rivers are thought to be controlled by similar processes to the Klip River. This work focuses primarily on the Ovens-King River, and is largely ongoing, in collaboration with Ian Rutherfurd (Melbourne). A description of the river and its anabranching channels can be found in Marren & Woods (2011). A related project, which considers the impact dams might have on the floodplains of lowland rivers of this type, resulted in a large ‘traditional’ review paper (Marren et al., 2014) and a systematic review which tested the strength of the patterns found by the traditional review using a ‘causal criteria’ approach (Grove et al., 2012).

Corryong Creek and the Nariel Valley – a catchment scale project

Corryong Creek is a 980km2 catchment in northeast Victoria, Australia. It is 115 km long and has its headwaters in the Victoria high country at Mount Pinnibar (1772m) and joins the River Murray at 244m, making it a relatively steep river by Australian standards. Below an elevation of 470m there is a well-developed, but relatively thin floodplain. The lower part of the river is called Corryong Creek, the middle river is referred to as Nariel Creek, and the headwater reaches are known as Wheelers Creek. The catchment is subjected to catastrophic bushfires (most recently in 2003 and 1939), as well as irregular floods interspersed with droughts. The most recent floods were in 2010 to 2012, following the end of the Millennium Drought.

I first visited the catchment in 2010, before the drought broke. When I next visited the first flood had taken place and there was extensive erosion along the length of the river. I have a paper currently in preparation which interprets the distribution of this erosion and the relative importance of stream power versus the stabilising influence of riparian vegetation (which is entirely non-native willow trees). The distribution of erosion also seems to be influenced by the previous history – some reaches which had widened in the past were stable, with previous instability largely due to mid-twentieth century management works (straightening and clearing). Because of this, I became interested in the history of the river following European settlement in 1839. Anthropogenic modifications have interacted with the El Nino/La Nina cycle to produce periods of instability and instability. These findings are presented in Teo & Marren (2015).

More recently still, I have become interested in the catchment as an archive of extreme bushfires. This was motivated by the presence of abundant charcoal in the floodplain stratigraphy, which when radiocarbon dated yielded ages spread across the last 2,000 years. In search of a site with a longer depositional record, a series of alluvial fans which transfer sediment from the surrounding hillsides onto the floodplain have been trenched. These have yielded a stratigraphy of repeated bushfires stretching through the entire Holocene. Work is currently underway to relate this stratigraphy to the Holocene climatic record, and ultimately the aim is to use the catchment to answer the question, “do bushfires enhance landscape denudation, or just facilitate the transfer of already weathered materials?”

This work is taking place in collaboration with Petter Nyman and Tony Lovell (Melbourne), Hugh Smith (Liverpool), Steph Kermode (Wollongong/ANSTO), Elisha Teo (Singapore) and Katherine Welsh (Chester).

Published work

Journal Articles
  • Marren, P.M. 2016. Bar deposition in glacial outburst floods: scaling, post-flood reworking, and implications for the geomorphological and sedimentary record. Géomorphologie: relief, processus, environnement 22, 51-60.
  • Roussel, E., Toumazet, J.-P., Marren, P.M.,  Cossart, E. 2016. Iceberg jam floods in Icelandic proglacial rivers: testing the self-organized criticality hypothesis. Géomorphologie: relief, processus, environnement 22, 37–49.
  • Teo, E.A., Marren, P.M. 2015. Interaction of ENSO-driven flood variability and anthropogenic changes in driving channel evolution: Corryong/Nariel Creek, Australia. Australian Geographer 46, 339–362.
  • Marren, P.M., Toomath, S.C. 2014. Channel pattern of proglacial rivers: topographic forcing due to glacier retreat. Earth Surface Processes and Landforms 39, 943–951.
  • Marren, P.M., Grove, J.R, Webb, J.A., Stewardson, M.J. 2014. The potential for dams to impact lowland meandering river floodplain geomorphology. The Scientific World Journal, vol. 2014, Article ID 309673, 24 pages. doi: 10.1155/2014/309673.
  • Carrivick, J.L., Tweed, F.S., Carling, P., Alho, P., Marren, P.M., Staines, K., Russell, A.J., Rushmer, E.L., Duller, R., 2013. Discussion of ‘Field evidence and hydraulic modeling of a large Holocene jökulhlaup at Jökulsá á Fjöllum channel, Iceland’ by Douglas Howard, Sheryl Luzzadder-Beach and Timothy Beach, 2012. Geomorphology 201, 512–519.
  • Marren, P.M., Toomath, S.C. 2013. Fluvial adjustments in response to glacier retreat: Skaftafellsjökull, Iceland. Boreas 42, 57–70.
  • Grove, J.R., Webb, J.A., Marren, P.M., Stewardson, M.J., Wealands, S. 2012. High and Dry: An investigation using the Causal Criteria methodology to investigate the effects of regulation, and subsequent environmental flows, on floodplain geomorphology. Wetlands 32, 215–224.
  • McCarthy, T.S., Tooth, S., Jacobs, Z., Rowberry, M.D., Thompson, M., Brandt, D., Hancox, P.J., Marren, P.M., Woodborne, S., Ellery W.N. 2011. The origin of the Nyl River floodplain wetland, Limpopo Province, South Africa: trunk-tributary river interactions in a dryland setting. South African Geographical Journal 93, 172–190.
  • McCarthy, T.S., Ellery, W.N., Backwell, L., Marren, P., de Klerk, B., Tooth, S., Brandt, D., Woodborne, S. 2010. The character, origin and palaeoenvironmental significance of the Wonderkrater spring mound, South Africa.  Journal of African Earth Sciences 58, 115–126.
  • Russell, A.J., Tweed F.S., Roberts, M.J., Harris, T.D., Gudmundsson, M.T., Knudsen, Ó., Marren, P.M. 2010. An unusual jökulhlaup resulting from subglacial volcanism, Sólheimajökull, Iceland. Quaternary Science Reviews 29, 1363–1381.
  • Hassan, M.A., Marren, P.M., Schwartz, U. 2009.  Bar structure in an arid ephemeral stream.  Sedimentary Geology 221, 57–70.
  • Carrivick, J.L., Russell, A.J., Rushmer, E.L., Tweed, F.S., Marren, P.M., Deeming, H., Lowe, O. 2009. Geomorphological evidence towards a de-glacial control on volcanism. Earth Surface Processes and Landforms 34, 1164–1178.
  • Marren, P.M., Russell, A.J., Rushmer, E.L. 2009. Sedimentology of a sandur formed by multiple jökulhlaups, Kverkfjöll, Iceland. Sedimentary Geology 213, 77–88.
  • Marren, P.M., McCarthy, T.S., Tooth, S., Brandt, D., Stacey, G.C., Leong, A., Spottiswoode, B. 2006. A comparison of mud- and sand-dominated meanders in a downstream coarsening reach of the mixed bedrock-alluvial Klip River, eastern Free State, South Africa. Sedimentary Geology 190, 213–226.
  • Russell, A.J., Roberts, M.J., Fay, H., Marren, P.M., Cassidy, N.J., Tweed, F.S., Harris, T. 2006. Icelandic jökulhlaup impacts: implications for ice-sheet hydrology, sediment transfer and geomorphology. Geomorphology 75, 33–64.
  • Marren, P.M. 2005. Magnitude and frequency in proglacial rivers: a geomorphological and sedimentological perspective. Earth-Science Reviews 70, 203–251.
  • Marren, P.M. 2004. Present-day sandurs are not representative of the geological record. Sedimentary Geology 152, 1-5 (2002). Discussion. Sedimentary Geology 164, 335–340.
  • Marren, P.M. 2002. Fluvial-lacustrine interaction on Skeiðarársandur, Iceland: implications for sandur evolution. Sedimentary Geology 149, 43–58.
  • Marren, P.M. 2002. Glacier margin fluctuations, Skaftafellsjökull, Iceland: implications for sandur evolution. Boreas 31, 75–81.
  • Knudsen, Ó., Marren, P.M. 2002. Sedimentation in a volcanically dammed valley, Brúarjökull, northeast Iceland. Quaternary Science Reviews 21, 1677–1692.
  • Marren, P.M. 2001. Sedimentology of proglacial rivers in eastern Scotland during the Late Devensian. Transactions of the Royal Society of Edinburgh: Earth Sciences 92, 149–171.
  • Russell, A.J., Knudsen, Ó., Fay, H., Marren, P.M., Heinz, J., Tronicke, J. 2001. Morphology and sedimentology of a giant supraglacial, ice-walled, jökulhlaup channel, Skeiðarárjökull, Iceland: implications for esker genesis. Global and Planetary Change 28, 203–226.
  • Russell, A.J., Knudsen, Ó., Maizels, J.K., Marren, P.M. 1999. Channel cross-sectional area changes and peak discharge calculations in the Gígjukvísl river during the November 1996 jökulhlaup, Skeiðarársandur, Iceland. Jökull 47, 45–58.
  • Russell, A.J., Marren, P.M. 1998. A Younger Dryas (Loch Lomond Stadial) jökulhlaup deposit, Fort Augustus, Scotland. Boreas 27, 231–242.
Book Chapters 
  • Ellery, W.N., Grenfell, S.E., Grenfell, M.C., Powell, R., Kotzee, D.C., Marren, P.M., Knight, J. 2016. Wetlands in southern Africa: a geomorphic threshold perspective. In: J. Knight, S. Grab (eds.), Quaternary Environmental Change in Southern Africa: Physical and Human Dimensions. Cambridge University Press, 188–202.
  • Marren, P.M., Hassan, M.A., Alila, Y.  2013.  Hydrological impacts of mountain pine beetle infestation: potential for river channel changes. In: A. Gelfan, D. Yang, Y. Gusev, H. Kunstmann (eds.), Cold and Mountain Region Hydrological Systems under Climate Change: Towards Improved Projections. IAHS Publication 360, 77–82.
  • Marren, P.M., Woods, K.L.M. 2011. Inundation of anabranching river flood plain wetlands: the Ovens River, Victoria, Australia. In: C. Abesser, G. Nützmann, M.C. Hill, G. Blöschl, E. Lakshmanan (eds.), Conceptual and Modelling Studies of Integrated Groundwater, Surface Water, and Ecological Systems. IAHS Publication 345, 229–234.
  • Marren, P.M. 2010. Geothermal Features.  In: B. Warf (ed.), Encyclopedia of Geography. SAGE Publications, Thousand Oaks, 1270–1274.
  • Marren, P.M., Schuh, M. 2009. Criteria for identifying jökulhlaup deposits in the sedimentary record. In: D. Burr, V.R. Baker, P.A. Carling (eds.), Megaflooding on Earth and Mars. Cambridge University Press, 225–242.
  • Russell, A.J., Fay, H., Marren, P.M., Tweed, F.S., Knudsen, Ó. 2005. Icelandic jökulhlaup impacts. In: C.J. Caseldine, A.J. Russell, J. Harðardóttir, Ó. Knudsen (eds.), Iceland: Modern Processes and Past Environments. Developments in Quaternary Science 5, Elsevier, Amsterdam, 153–203.
  • Cassidy, N.J., Russell, A.J., Marren, P.M., Fay, H., Rushmer, E.L., van Dijk, T.A.G.P., Knudsen, Ó. 2003. GPR-derived architecture of November 1996 jökulhlaup deposits, Skeiðarársandur, Iceland. In: C.S. Bristow, H. Jol (eds.), Ground Penetrating Radar in Sediments. Geological Society of London Special Publication 211, 153–166.
  • Marren, P.M., Russell, A.J., Knudsen, Ó. 2002. Discharge magnitude and frequency as a control on proglacial fluvial sedimentary systems. In: F. Dyer, M.C. Thoms, J.M. Olley (eds.), The Structure, Function and Management Implications of Fluvial Sedimentary Systems. IAHS Publication 276, 297–303.
  • Rushmer, E.L., Russell, A.J., Knudsen, Ó., Tweed, F.S., Marren, P.M. 2002. The role of hydrograph shape in controlling glacier outburst flood (jökulhlaup) sedimentation. In: F. Dyer, M.C. Thoms, J.M. Olley (eds.), The Structure, Function and Management Implications of Fluvial Sedimentary Systems. IAHS Publication 276, 305–313.
  • Marren, P.M. 2002. Criteria for distinguishing high magnitude flood events in the proglacial fluvial sedimentary record. In: Á. Snorrason, H.P. Finnsdóttir, M. Moss (eds.), The Extremes of the Extremes: Extraordinary Floods. IAHS Publication 271, 237–241.
  • Russell, A.J., Tweed, F.S., Knudsen, Ó., Roberts, M.J., Harris, T.D., Marren, P.M. 2002. Impact of the July 1999 jökulhlaup, on the proximal river Jökulsá á Sólheimasandi, Mýrdalsjökull Glacier, southern Iceland. In: Á. Snorrason, H.P. Finnsdóttir, M. Moss (eds.), The Extremes of the Extremes: Extraordinary Floods. IAHS Publication 271, 249–254.
  • Russell, A.J., Marren, P.M. 1999. Proglacial fluvial sedimentary sequences in Greenland and Iceland: a case study from active proglacial environments subject to jökulhlaups. In: A.P. Jones, M.E. Tucker, J.K. Hart (eds.), The Description and Analysis of Quaternary Stratigraphic Field Sections. Quaternary Research Association Technical Guide 7, 171–208.
Refereed Conference Papers 
  • Zhang, N., Rutherfurd, I., Marren, P. 2016. Impact of large instream logs on river bank erosion.  Proceedings of the 11th International Symposium on Ecohydraulics, Melbourne. Paper 25971.
  • Teo, E.A., Marren, P.M. 2014. The evolution of Corryong/Nariel Creek since European settlement: implications for on-going management prioritisation. In: I.D. Rutherfurd, G.J. Vietz (eds.), Proceedings of the 7th Australian Stream Management Conference: Catchment to Coast. Townsville, Queensland, 25-35.
  • Marren, P.M., Grove, J.R., Webb, J.A., Stewardson, M.J. 2014. The impact of dams on floodplain geomorphology: are there any, should we care, and what should we do about it? In: I.D. Rutherfurd, G.J. Vietz (eds.), Proceedings of the 7th Australian Stream Management Conference: Catchment to Coast. Townsville, Queensland, 74-80.
  • Marren, P.M., Smith, H.G. 2012. Channel changes on Corryong Creek, NE Victoria following drought-ending floods: implications for channel and riparian vegetation management. In: J.R. Grove, I.D. Rutherfurd (eds.), Proceedings of the 6th Australian Stream Management Conference: Managing for Extremes. River Basin Management Society, Australia, 31–38.