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Overview

The Geodetic Survey section of Surveyor-General Victoria and the Geological Survey of Victoria are collaborating with Geoscience Australia (GA) to capture airborne gravity data over targeted regions of Victoria. The Geological Survey of Victoria is part of the Department of Jobs Precincts and Regions (DJPR).

The objective of the project is to collect consistent and evenly distributed gravity measurements.

The new gravity data will significantly improve Victoria’s gravity model and the accuracy of real-world heights from GPS positioning. The data will also be used by geoscientists to further their understanding of southeast Australia’s geological "architecture" and how it has evolved over time.

Gravity surveys in Victoria

Victoria has some of the best coverage of ground gravity data in Australia, but some areas such as the alpine, coastal and desert regions are difficult to access. This limits gravity data coverage, with corresponding local uncertainty in the gravity model.

Airborne gravity data will be collected over large regions of the state, including the central coast, Melbourne, the Victorian Alps and eastern Victoria. The airborne gravity survey will deliver consistent and evenly distributed gravity measurements across these areas, with minimal disturbance to land users and the environment.

The survey will involve flights over diverse land types, including:

  • urban and rural areas
  • mountainous and coastal terrain
  • national and state parks and reserves

Airborne gravity surveys have been safely and successfully completed across coastal Gippsland (2011), southwest Victoria (2019) and near Bendigo (2004, 2019).

Map of Victoria showing planned survey area
Map of planned survey area

Flight operations and the impact on the environment

The airborne surveys are expected to start in late 2020 and will take several months to complete.

The surveys will be conducted by an experienced specialist contractor flying a fixed wing aircraft along a planned route with flight lines spaced 500 metres to 2 km apart. The aircraft will fly in public airspace at a nominated ground clearance of 150 metres, increasing to 300 metres over built-up areas.

An independent air safety audit will be conducted on the aircraft and flight plans. Flying will only occur in favourable weather conditions.

The survey planes are normal aircraft with scientific instruments on board. Noise levels on the ground will be transient and less than the sound of a passing motorbike.

Specialised gravity-sensing instrumentation will be used to measure extremely small variations in the earth’s natural gravitational pull. The gravity instruments are passive and do not emit any signals, or impact people, animals or infrastructure in any way.

Survey benefits

The data and gravity model will improve height determination from GPS positioning to an accuracy of a few centimetres. The changes will support productive and effective land management and technological innovation, as well as meeting community expectations of reliable GPS positioning in Victoria.

The new data will advance the geoscience that assists the Victorian Government to manage its earth resources, infrastructure and natural hazards. It will also assist the state’s resources sector, which contributes to regional jobs and economic growth.

Data availability

The data will be freely available through the Victorian Government’s open data platforms and licensed for public use. The data will also be included in the national geoscience database and data portals managed by Geoscience Australia.

Page last updated: 18/02/21