# Land Cover Mapping: Australia

## Science Center Objects

Australia’s agricultural industry has evolved significantly within the last decade. Change in agriculture, whether it is an increase in land used for production or the types of crops being produced, has an impact on land-cover soil properties and water availability. Landsat imagery is used in monitoring irrigation areas and dry land agricultural areas to detect changes in agricultural practices over time. Additionally, land cover is also used in benchmarking of water-use efficiency which supports irrigation water management at the catchment level.

Authors : Larisa Serbina and Holly Miller

Australia’s agricultural industry has evolved significantly within the last decade. Change in agriculture, whether it is an increase in land used for production or the types of crops being produced, has an impact on land-cover soil properties and water availability. Landsat imagery is used in monitoring irrigation areas and dry land agricultural areas to detect changes in agricultural practices over time. Additionally, land cover is also used in benchmarking of water-use efficiency which supports irrigation water management at the catchment level. Victoria’s Department of Environment and Primary Industries has been using a historical land cover data set from Landsat in a major cropping region in central Victoria. The NDVI and land-cover classifications from the Landsat images are used to conduct the analyses. Figure 1 shows largely a dry land cropping area in the Wimmera Region. Historical soil and land-use information from government surveys will be used to compare against the Landsat data. The goal is to examine the linkages between the historical soil information and imagery to investigate influences of long-term farming trends on soil properties. This project would not be undertaken if the archive of Landsat imagery was not available. The historical continuity of Landsat data allows for the observation of changes in land cover over time since the 1980’s, which is not possible with other satellite imagery.

NDVI (Normalized Difference Vegetation Index) maps derived from Landsat 5 imagery in the Wimmera Region, north-central Victoria, Australia. Courtesy of the Victoria Department of Environment and Primary Industries.

Landsat imagery is also used to create an annual land cover map for a section of the Goulburn-Murray Irrigation Region. This map identifies the type of pastures grown in the area (seasonal/annual/ perennial) and is then used in other projects. The production of this information relies on NDVI and thermal information and would be restricted without the availability of the Landsat data. If Landsat were not available, suitable alternatives would incur costs which would limit the amount of work able to be done. In the absence of Landsat data, the alternative source of imagery which could be used is ASTER. For one season of land cover of the Goulburn-Murray Region, ASTER images would cost about $14,462 ($15,000 in Australian dollars) at present. The ASTER sensor is onboard the aging Terra satellite with no continuity plan in place. In the near future, Landsat 8 will be the only available satellite with moderate spatial resolution and the thermal band. Future land-cover monitoring for this region will depend solely on Landsat data (Mohammad Abuzar, Elizabeth Morse-McNabb and Kathryn Sheffield, oral commun. and written commun., 2013).

References:

• Dr. M. Abuzar, Senior Research Scientist, Agriculture Research, Department of Environment and Primary Industries, Victoria, Australia.
• Dr. Elizabeth Morse-McNabb, Senior Research Scientist, Agriculture Research, Department of Environment and Primary Industries, Victoria, Australia.
• Dr. Kathryn Sheffield, Research Scientist, Agriculture Research, Department of Environment and Primary Industries, Victoria, Australia.