may be surprised to learn that water variability also impacts some of the country’s driest environments. Bureau of Meteorology Research Scientist Dr Blair Trewin explains this variability through the example of Lake Carnegie in central Western Australia. Lake Carnegie receives an average annual rainfall of only 225 millimetres per year. (For comparison, Melbourne’s annual average rainfall is 518 millimetres, while Adelaide receives 547 millimetres per year, Sydney 1042 millimetres and Brisbane 1080 millimetres.) Yet on just one day in 2020, 270 millimetres of rain fell on Lake Carnegie (more than its yearly average). The difference in the landscape can be clearly seen in FIGURE6 . Similar variability can also be observed in FIGURE7 , which shows many other areas of extreme rainfall variability, including locations in outback New South Wales, Queensland, Western Australia, South Australia and the Northern Territory.
FIGURE6 Lake Carnegie as it is regularly seen (a) and after unseasonably high rainfall (b)
(a)
(b)
2020
2016
FIGURE7 Australia’s rainfall variability from 1900 to 2019
0
500
1000 km
Index of rainfall variability
Moderate (0.75–1.0)
Very high (1.5–2.0)
Low to moderate (0.5–0.75)
High (1.25–1.5)
Low (0–0.5)
Moderate to high (1.0–1.25)
Source: Map redrawn by Spatial Vision © Copyright Commonwealth of Australia 2020, Bureau of Meteorology.
274 Jacaranda Humanities Alive 7 Victorian Curriculum Third Edition
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