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INTRODUCTION

The Australian Government is investing in a world first analysis platform for satellite imagery and other Earth observations.

Digital Earth Australia (DEA) will build on the globally recognised innovation, the Australian Geoscience Data Cube; winner of the 2016 Content Platform of the Year at the Geospatial World Leadership Awards.

DEA translates almost 30 years of Earth observation satellite imagery into information and insights about the changing Australian landscape and coastline, providing a ground-breaking approach to organising, analysing, and storing vast quantities of data.

From sustainably managing the environment to developing resources and optimising our agricultural potential, Australia must overcome a number of challenges to meet the needs of its growing population in a time of increased climate variability. DEA will deliver a unique capability to process, interrogate, and present Earth observation satellite data in response to these issues. It will track changes across Australia in unprecedented detail, identifying soil and coastal erosion, crop growth, water quality, and changes to cities and regions.

The following products provide examples of how, by providing easy access to free and open Earth observation data, DEA will unlock innovation and capability across government, industry, and the research community.

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WATER OBSERVATIONS FROM SPACEThe Water Observations from Space (WOfS) product is the world’s first continent-scale map of the presence of surface water1.

WOfS provides insight into the behaviour of surface water across Australia through time, from 1987 to today. It highlights where water is normally present in our landscape, where water is seldom observed, and where inundation has occasionally occurred.

Severe floods are a feature of the Australian climate and landscape and are likely to continue with increasing regularity and severity. WOfS helps us to understand where flooding may have occurred in the past, which allows us to reduce its impact in the future through proper disaster planning and initiatives supporting communities’ preparedness and disaster resilience. WOfS is also an invaluable information source for the Australian Flood Risk Information Portal, which enables flood information held by different sources to be accessible from a single online location.

1 N. Mueller, A. Lewis, D. Roberts, S. Ring, R. Melrose, J. Sixsmith, L. Lymburner, A. McIntyre, P. Tan, S. Curnow, A. Ip, Water observations from space: Mapping surface water from 25 years of Landsat imagery across Australia, Remote Sensing of Environment, 174, 341-352, ISSN 0034-4257.

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FRACTIONAL COVERFractional Cover (FC) splits the landscape into three parts, or fractions; green (leaves, grass, and growing crops), brown (branches, dry grass or hay, and dead leaf litter), and bare ground (soil or rock). DEA uses this to characterise every 25 m square of Australia for any point in time from 1987 to today and to inform a broad range of natural resource management issues2.

FC can provide insights into areas of dry or dying vegetation and bare soil, as well as allowing the mapping of living vegetation extent. For example, FC can be used to monitor where animals spend time grazing, providing valuable information for land owners to ensure all of their feed is used. By monitoring the proportion of living vegetation and bare ground through time, land managers can determine which parts of the property show heavier grazing. Placing additional water points in the ungrazed areas will help move the livestock into those areas.

2 The method used to separate out these parts of the landscape was developed by the Joint Remote Sensing Research Program, a collaboration between state agencies to develop the use of remote sensing in environmental management. Scarth, P., Röder, A., Schmidt, M., 2010. Tracking grazing pressure and climate interaction - the role of Landsat fractional cover in time series analysis. In: Proceedings of the 15th Australasian Remote Sensing and Photogrammetry Conference (ARSPC), 13–17 September, Alice Springs, Australia. Alice Springs, NT.

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NORMALISED DIFFERENCE VEGETATION INDEXNormalised Difference Vegetation Index (NDVI) provides us with the ability to assess the extent of living green vegetation across the entire Australian continent at any point in time from 1987 to today. NDVI provides valuable insight into the health and/or growth of vegetation over time, whilst also supporting the mapping of different land cover types across Australia.

The way NDVI changes over time can be used to identify areas where there has been a sudden drop or increase in the amount of vegetation.  Sudden drops in NDVI can be caused by a range of processes including tree clearing, cropping, or severe bushfires. Sudden rises in NDVI can be the result of vegetation responding to increased water availability, crop growth, and greening of irrigated pasture. 

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INTERTIDAL EXTENTS MODELThe Intertidal Extents Model (ITEM) product provides valuable information regarding the exposed intertidal zone; the area between the land and sea that can be observed between the highest and lowest tide3.

ITEM can provide the extent and relative elevation profile of the intertidal zone, drawing on almost 30 years of Earth Observation data. Information from ITEM complements existing data, providing a more realistic representation and a better understanding of Australia’s vast coastline.

The knowledge provided by ITEM can contribute to a broad range of applications, including environmental monitoring for migratory bird species, habitat mapping in coastal regions, hydrodynamic modelling, and geomorphological studies of features in the intertidal zone.

3 Sagar, S., Roberts, D., Bala, B., Lymburner, L., 2017. Extracting the intertidal extent and topography of the Australian coastline from a 28 year time series of Landsat observations. Remote Sensing of Environment 195, 153–169.

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SURFACE REFLECTANCEThe Surface Reflectance product is the fundamental starting point for many analyses. Put simply, the Surface Reflectance product turns the information recorded by an Earth observing satellite into a measurement of the characteristics of the surface of the earth4. It accounts for complex variations in the atmosphere, sun position, and view angle at the time each satellite image is captured, and corrects the image accordingly. This allows for a more accurate comparison of imagery captured at different times, by different sensors, in different seasons, and in different locations. It also indicates where the image contains missing data, has been affected by cloud or cloud shadow, or has been affected in other ways.

These corrections have been applied to all satellite imagery from 1987 to today, providing a rich history of Australia’s changing landscape and coasts.

4 Li, F., Jupp, D.L.B., Thankappan, M., Lymburner, L., Mueller, N., Lewis, A., and Held, A., 2012. A physics-based atmospheric and BRDF correction for Landsat data over mountainous terrain. Remote Sensing of Environment 124, 756–770.

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FURTHER INFORMATION

Email: Earth.Observation@ga.gov.au www.ga.gov.au/dea

© Commonwealth of Australia (Geoscience Australia) 2017

With the exception of the Commonwealth Coat of Arms and where otherwise noted, this product is provided under a Creative Commons Attribution 4.0 International Licence. (http://creativecommons.org/licenses/by/4.0/legalcode)

Geoscience Australia has tried to make the information in this product as accurate as possible. However, it does not guarantee that the information is totally accurate or complete. Therefore, you should not solely rely on this information when making a commercial decision.

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eCat 110601 | GA PP-439