New research into storm patterns warns that flash floods are likely to sweep across the Australian landscape with increasing intensity, particularly in urban or residential areas.
Peak rainfall is predicted to soar with rising surface temperatures as the world’s largest island – and also its smallest continent − experiences ever greater extremes of heat.
Civil engineers from the Water Research Centre at the University of New South Wales (UNSW) report in Nature Geoscience that they looked at 40,000 storms across the whole of the continent over the last 30 years and identified a pattern that warmer temperatures are linked to disruptive rainfall events.
“Our results were consistent across all the climate zones in Australia, regardless of season or storm type, without exception,” says Professor Ashish Sharma, one of the study’s authors.
“This was an unexpected finding, and it supports our hypothesis that increasing temperatures are changing rainfall patterns. It means that most people in Australia can expect to see intensification in the magnitude of flash flooding in smaller catchments, particularly in urban or residential areas.”
The researchers worked from data from the 500 largest storms as measured by total rainfall at 79 locations. They looked not so much at the total volume of rainfall during a storm as at the pattern of intensity of rainfall at 12-minute intervals during each storm’s duration.
They projected their findings into a hotter world and calculated that a 5°C rise in temperatures could be accompanied by up to 20% more flood peaks in urban catchment areas. Some cities could experience much worse: for Perth, the rise is projected at 10%, for Sydney 12%, and for Darwin a whopping 45%.
Australia is a landscape of extremes of heat and drought and occasional devastating flood. It is also a land of paradox.