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Soil erosion rates on the Nullarbor plain using fallout radionuclides and remote sensing

Gillieson, D.S. Mr; Ph: (02) 6268 8305; Fax: (02) 6268 8313; d-gillieson@adfa.edu.au

Wallbrink, P. Dr; Ph: (02) 6246 5823; Fax (02) 6246 5800

Research organisation: University of New South Wales, University College, Department of Geography and Oceanography, Australian Defence Force Academy, Campbell ACT 2601; CSIRO Land and Water, GPO Box 1666, Canberra ACT 2601

Collaborators: Related projects (University of New South Wales and CSIRO Wildlife and Ecology): spatial analysis of watering points in Australian rangelands.

Sponsor: ARC: Australian Research Council; UNSW; CSIRO Collaborative Research Grant

Objectives:

1. To determine the spatial extent of soil erosion and recovery over 20 years including 1972-73 and 1988 droughts;

2. To determine the rates of soil erosion by wind and water processes in relation to vegetation change and drought;

3. To study the role of rainfall variability and grazing in landscape ecology.

Methodology:

1. Use of spatial band ratios of MSS and TM imagery for five-year intervals from 1972 to 1991, for identification of eroded areas on two properties at Mundrasilla and Koomalda.

2. 137-caesium inventories of undisturbed and eroded sites on both properties.

3. Sediment tracing using 226-radium and 232-thorium to distinguish products of water and wind erosion.

Progress:

We are using remote sensing and GIS to look at rates of landscape change in the arid zone, especially on the Nullarbor Plain and at sites in western NSW. Time series analysis of vegetation and soil indices derived from Landsat data provide estimates of the change in vegetation cover in response to grazing, droughts and floods. The monitoring of ecosystem processes is of high priority for assessing the impacts of land use change and climatic variability, for rehabilitation and to increase scientific understanding of landscape dynamics. We are using fallout radionuclide methods that provide estimates of the rates of sediment movement in landscapes dominated by wind erosion. These patterns and rates have been compared to ground studies of vegetation structure and soil surface condition. The inventories of radionuclide tracers provide a good surrogate for geomorphic processes and sediment patterns and are thus a good tool for monitoring by managers concerned with acceptable rates of landscape change.

Period: starting date 1991-07; completion date 1994-12

Status: completed

Keywords: soil erosion

Publications:

Gillieson, D. (1993). Environmental change and human impact on arid and semi-arid karsts of Australia In Williams, P. (ed.) Karst Terrains: Environmental changes and human impact, Catena Supplement 25, 127-146 .

Gillieson, D. (1997). Environmental change and human impact on the arid karst of the Nullarbor Plain, Australia, Proceedings of the 12th International Congress of Speleology, La Chaux de Fonds, Switzerland, 10-17 August 1997, 1, 327-330.

Gillieson, D. (1997). Dynamics of soil - vegetation systems on limestone and karst management, Proceedings of the 11th Australasian Cave & Karst Management Association Conference, Hobart, Tasmania, 29April - 8 May 1995, pp 25-33.

Gillieson, D., Cochrane, A. and Murray, A. (1994). Surface hydrology and soil erosion in an arid karst: the Nullarbor Plain, Australia. Environmental Geology 23(2), 125-133.

Gillieson, D., Wallbrink P. and Cochrane, A. (1996). Vegetation change, erosion risk and land management on the Nullarbor Plain, Australia. Environmental Geology 28(3), 145-153.

Gillieson, D., Wallbrink P., Murray, A. and Cochrane, A. (1996). Estimation of wind erosion using GIS modelling and caesium-137 on the Nullarbor Plain karst, Australia. Zeitschrift für Geomorphologie Suppl.Bd.105, 73-90.

Landsberg, J. and Gillieson, D. (1995). Looking beyond the piospheres to locate biodiversity reference areas in Australia's rangelands, Proceedings of the Fifth International Rangelands Congress, Salt Lake City, Utah, 23-28 July 1995, 1, 304-305.

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