Geoscientific land management planning in salt-affected areas*

Simon Abbott; David Chadwick; Greg Street

doi:10.1071/EG07002

RESEARCH ARTICLE

Previous Contents Vol 38(1)

Geoscientific land management planning in salt-affected areas^*

Simon Abbott ¹ ⁴ David Chadwick ² Greg Street ³

+ Author Affiliations

- Author Affiliations

¹ CRC LEME, Department of Exploration Geophysics, Curtin University of Technology, Bentley WA 6011, Australia.

² The Meadows, Broomehill WA 6318, Australia.

³ Department of Exploration Geophysics, Curtin University of Technology, Bentley WA 6011, Australia.

⁴ Corresponding author. Email: simon.abbott@postgrad.curtin.edu.au

Exploration Geophysics 38(1) 98-109 https://doi.org/10.1071/EG07002
Submitted: 14 July 2006 Accepted: 17 October 2006 Published: 5 April 2007

Abstract

Over the last twenty years, farmers in Western Australia have begun to change land management practices to minimise the effects of salinity to agricultural land. A farm plan is often used as a guide to implement changes. Most plans are based on minimal data and an understanding of only surface water flow. Thus farm plans do not effectively address the processes that lead to land salinisation.

A project at Broomehill in the south-west of Western Australia applied an approach using a large suite of geospatial data that measured surface and subsurface characteristics of the regolith. In addition, other data were acquired, such as information about the climate and the agricultural history. Fundamental to the approach was the collection of airborne geophysical data over the study area. This included radiometric data reflecting soils, magnetic data reflecting bedrock geology, and SALTMAP electromagnetic data reflecting regolith thickness and conductivity. When interpreted, these datasets added paddock-scale information of geology and hydrogeology to the other datasets, in order to make on-farm and in-paddock decisions relating directly to the mechanisms driving the salinising process. The location and design of surface-water management structures such as grade banks and seepage interceptor banks was significantly influenced by the information derived from the airborne geophysical data. To evaluate the effectiveness of this planning, one whole-farm plan has been monitored by the Department of Agriculture and the farmer since 1996. The implemented plan shows a positive cost–benefit ratio, and the farm is now in the top 5% of farms in its regional productivity benchmarking group.

The main influence of the airborne geophysical data on the farm plan was on the location of earthworks and revegetation proposals. There had to be a hydrological or hydrogeological justification, based on the site-specific data, for any infrastructure proposal. This approach reduced the spatial density of proposed works compared to other farm plans not guided by site-specific hydrogeological information.

Key words: airborne geophysics, dryland salinity, farm planning.

Acknowledgments

The authors acknowledge the support of Curtin University of Technology – Department of Exploration Geophysics; CRC LEME for scholarship and research funds; Jayson Meyers for his review of this text; and the other Broomehill project team members – Pat Cunneen, Karina Tedesco, Marty and Ros Ladyman, Prasanth Nallan, and Gabriella Pracilio.

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^* Presented at the 18th ASEG Geophysical Conference and Exhibition (AESC 2006), July 2006.