Geography

Geography

Maree Hemmingsen

Ph.D. Research Profile: Maree Hemmingsen

The abrasion of greywacke on a mixed sand and gravel coast

Supervisor

Professor R. M. Kirk
Department of Geography

Co-Supervisors

Assoc. Professor Ian Owens

Dr Martin Single
Department of Geography

Ashburton River Mouth

This research is focusing on the abrasion of greywacke on a mixed sand and gravel coast. The purpose of this research is to examine the role abrasion plays in the overall attrition of the sediment population on a mixed sand and gravel beach. Mixed sand and gravel shorelines present the maximum range of particle sizes to reworking by waves so that the beaches developed on them might be expected to be morphologically distinctive and dynamically complex (Kirk, 1980). These beaches are distinctive, not only in terms of grain size, but also in their response to changing wave energetics, profile characteristics, sediment transport and evolution (Carter, 1988).

It is well established that the coastline of the Canterbury Bight between Timaru and the southern end of Kaitorete Barrier at Taumutu is in long term erosion. Average erosion rates are in the order of 1-1.5m/yr. The 29 km long Kaitorete Barrier has been stable, or only mildly accretional since the 1860's (Kirk, 1994) yet longshore sediment transport along the coast south of Taumutu is strongly net northward.

There are several large, braided rivers which drain from the rapidly eroding Southern Alps. Griffiths (1981) states that catchment-specific sediment yields average 1856± 261 tonne km-2yr-1 compared with the world average of 182 tonne km-2yr-1 and are among the highest known specific sediment yields. In addition to the river sources there are also sections of cliff which supply sediment to the coast. Flatman (1997) calculated that coastal cliff erosion, from the Rangitata River to the Rakaia River, contributed 228,339m3.yr-1 of sediment to the coast. His study found that cliff erosion rates varied from 0.03m.yr-1 to 1.09m.yr-1 and that as cliff height increased so did the erosion rate.

The Canterbury Bight coastline is apparently abundantly supplied with sediment which is subsequently transported northward at rates of around 40,645m3yr-1 (Flatman 1997) ultimately forming Kaitorete Barrier. Since the 1950's there has been very little accumulation of sediment against Banks Peninsula at the downdrift end. Kirk (1980), Flatman (1997) and others including Marshall (1927), Adams (1978) and Hicks (1998) have suggested that sediment is lost from the beaches due to abrasion of coarse material into fine sands, silt and mud. Abrasion rates ranging from 4.8 % (Adams, 1978) to 76.8% (Flatman, 1997) by beach volume have been proposed in attempts to derive a sediment budget for the Canterbury Bight. The work currently being researched here is a step towards deriving a more precise measure of abrasion for input to the sediment budget of the mixed sand and gravel beaches of the Canterbury Bight.

Ashburton alluvial cliffs

Other Research Interests

Quaternary geography is an area I have become passionate about following the completion of my M.A.(Hons) in Geography. Supervisor: Professor R. M. Kirk

For this research I focused on the Coastal Geomorphology of Te Waihora (Lake Ellesmere). This study not only looks at the contemporary shorelines but with the assistance of C14 dating confirms the existence of several other water bodies in the area. From this work I was able to reconstruct some of the evolutionary history of this water body from a bay to several exchanges between lake/estuary sequences and finally to the small coastal lake (or Waituna) that exists today.

Before studying at Canterbury I was involved in the Architectural industry. As such I have an interest in buildings and space. I am particularly interested in the changes in usage of space and the divisions of space both within and around buildings and the diurnal patterns of the usage of public space.

I am also interested in the Geography of Music, in particular the use of music as it relates to the environment. Protest music has a special place in New Zealand as a means of both expressing an opinion and informing the public of issues. Changes in the structure of broadcasting and technology have had a significant influence on this type of music and New Zealand music generally.

Kaitorete Barrier, Te Waihora (right)
and Pacific Ocean (left).

Awards/Prizes/Grants

  • 2003 NZGS2003 Conference Highly Commended Award for Best Student Papers
  • 2000 Environment Canterbury Ph.D. research grant
  • 1999 Canterbury Regional Council Ph.D. Research grant
  • 1998 University of Canterbury Doctoral Scholarship
  • 1998 Wearer of the Eileen Fairbairn Gown
  • 1998 George Jobberns Prize in Geography
  • 1997 Sir Neil Isaac Scholarship

Publications

  • Hemmingsen, M.A., (2001) The abrasion of "Greywacke" on a mixed sand and gravel coast, pp. 278-287. In Healey, T.R. (ed) (2001): International Coastal Symposium ( ICS 2000) "Challenges for the 21st Century in Coastal Science, Engineering and Environment." Journal of Coastal Research - Special Issue 34.
  • Hemmingsen, M.A. (2001) Radiocarbon age for shells from Lakelands, Lake Ellesmere (Te Waihora), N.Z. New Zealand Journal of Marine and Freshwater Research 35 (2) 329-334.
  • Single, M.B. & Hemmingsen, M.A., (2001) Chapter 12 "Mixed Sand and Gravel barrier Beaches of South Canterbury, New Zealand" p. 261-276 in J. Packham (ed.) Ecology and Geomorphology of Coastal Shingle . Smith Settle, England.

Technical Reports

  • Taylor, A.J, Hemmingsen, M.A, Kirk, R.M. & Single, MB (2001) Annual Monitoring - Lake Waikaremoana Shoreline Monitoring Network, March 2001. A report to Genesis Power, Land & Water Studies (International) Ltd, Christchurch, New Zealand.
  • Dawe, I & Hemmingsen, M., (2000). Lake Monowai Beach Profile Monitoring Network. A Report to Trust Power Limited. Land and Water Studies (International) Ltd. Christchurch, New Zealand.
  • Dawe, I & Hemmingsen, M., (1999). Catamaran Wake from "Fiordland Express" on the Shoreline of Lake Te Anau. A Report to Fiordland Travel, Te Anau. Land and Water Studies (International) Ltd. Christchurch, New Zealand.
  • Allan, J.C., Kirk, R.M., Hemmingsen, M. & Hart, D., (1999). Coastal Processes in Southern Pegasus Bay: A Review. A Report to Woodward-Clyde New Zealand Ltd. and the Christchurch City Council. Land and Water Studies (International) Ltd., Christchurch, New Zealand.

Conferences/Workshops attended

  • 2003. New Zealand Geographical Society "Windows on a changing world" 6-11 July 2003. Paper presented: "Reduction of sediments on the Canterbury Bight coast."
  • 2002. 10th Australia New Zealand Geomorphology Group (ANZGG) Conference, Kalgoorlie, Austrlia. Presentation: "Where does the sediment go? The abrasion of "greywacke" sediments on the mixed sand and gravel beaches of the Canterbury Bight".
  • 2001. "Marine Science Research for Integrated Coastal Management." Sponsored by the Centre of Excellence in Aquaculture and Marine Ecology, University of Canterbury/NIWA, 7 December 2001, Kaikoura, New Zealand. Presented 2 posters: (i) Where does the Sediment Go, (ii) The Ecology and Geomorphology of Te Waihora.
  • 2000. 9th Australia New Zealand Geomorphology Group (ANZGG) Conference, Wanaka, New Zealand. Presentation Where does the sediment go? The role of abrasion in a coastal sediment budget.
  • 2000. International Coastal Symposium 2000. "Challenges for the 21st Century in Coastal Science, Engineering and Environment". Rotorua, New Zealand. Presentation: The abrasion of "Greywacke" on a mixed sand and gravel coast.
  • 1999 Canterbury Coastal Group. Presentation: The abrasion of greywacke on a mixed sand and gravel coast.
  • 1999 Ecology and Geomorphology of Coastal Shingle - organised by the EUCC-UK. Wye College, Kent, UK. Poster Presentation: The Ecology and Geomorphology of Te Waihora, New Zealand
  • 1998 Canterbury Coastal Group. Presentation: The coastal geomorphology of Te Waihora.

Contact Details:

Room 307, Geography
Telephone: +64 3 364-2987, ext: 8123
e-mail: maree.hemmingsen@xtra.co.nz