Gamma-ray remote sensing

Gamma-ray remote sensing (gamma-radiometrics) measures natural low-level radioactivity from the top 35-50 cm of the Earth's surface, although deeper profiles may be inferred from this layer. Image maps of gamma-ray emitting elements may define soil types as well as physical and chemical processes. Image features of these processes can be used to define and mitigate environmental problems - see following examples:

Mapping salt-source areas in the Murray-Darling Basin

Areas of salt source materials, namely aeolian soils derived from a massive ancient salt-lake, are modeled from a regional gamma-ray image mosaic. Evidence for the validity of the model is found from salinity measured in deep boreholes. Further supporting evidence is the close correlation of salt-sources mapped by gamma-ray signatures and saline areas mapped by local Airborne Electro-Magnetic (AEM) surveys.

Read More: Bierwirth, P.N., and Brodie, R.S., 2006. Developing a salt source model for the Murray-Darling Basin from natural soil-radioactivity and geological data. BRS Report

Also: Bierwirth, P.N., and Brodie, R.S., 2008. Gamma-ray remote sensing of aeolian salt-sources in the Murray-Darling Basin, Australia. Remote Sensing of Environment. Vol 112/2 pp 550-559.

Bierwirth, P.N., 2008. Gamma-ray remote sensing of salt-source materials in the Murray-Darling Basin. 14th Australasian Remote Sensing and Photogrammetry Conference, Darwin (Paper) (Presentation)

Detecting Acid-Sulfate Soils Hotspots

Acid sulfate soils are a major environmental problem, being commonly found in coastal areas, and when disturbed produce acid at toxic levels. This chemical process produces a distinctive gamma-ray signature.

Read More: Bierwirth, P.N., and Brodie, R.S., 2005. Identifying acid sulfate soil hotspots from airborne gamma radiometric data & GIS analysis. BRS Report

Soil Mapping in a forested area:

Bierwirth, P.N., Aspin, S.J, Ryan, P. J., and McKenzie, N. J. (1998). Gamma-ray remote sensing of soil properties in a forested area near Batlow, NSW. Proceedings of the Ninth Australasian Remote Sensing Conference.

Gamma-ray remote sensing of soil properties near Wagga Wagga, NSW

Bierwirth,P.N,. Gessler,P. and McKane, D. (1996) Empirical investigation of airborne gamma-ray images as an indicator of soil properties - Wagga Wagga, NSW. 8th Australasian Remote Sensing Conference Proceedings. Canberra.

Investigation of airborne gamma-ray images as a rapid mapping tool for soil and land degradation - Wagga Wagga,NSW, AGSO Record 1996/22.

Read More:

Soil Mapping at Proserpine, North Queensland

Bierwirth, P.N., Hardy, S, Wilson, P., Philip, S., Smith, D., Heiner, I. and Grundy, M. (1997). Radio Ga Ga - Integrating gamma-radiometrics into landscape modeling of soil attributes; results of an ACLEP exchange. ACLEP Newsletter , vol 6, no 4, December, 1997