Mandie Sami reported this story on Tuesday, June 9, 2015 08:24:00

MICHAEL BRISSENDEN: Australia is apparently at increased risk of experiencing flash flooding as temperatures warm.



Conclusions published in the journal Nature Geoscience suggest that peak downpours during storms are intensifying at warmer temperatures, leading to greater flash flooding risks in urban centres.



The study's authors have pointed to recent extreme weather events in Sydney and Queensland as examples of what they've documented.



They're urging local councils to redesign sewerage and road infrastructure as a result.



Mandie Sami reports.



MANDIE SAMI: Civil engineers from the University of New South Wales have analysed 30 years of weather records from 79 locations across Australia.



They say the findings show that the most intense downpours of rain are getting more extreme at warmer temperatures, dumping larger volumes of water over less time, leading to more flash floods.



The University of New South Wales Professor Ashish Sharma co-authored the study.



ASHISH SHARMA: While it uses data from Australia it is actually very global in its reach because what we have gone about doing is we have just picked data from a lot of high quality rainfall stations in Australia.



And we are finding that this intensification that we are talking about, you know, the peak burst is actually getting even larger - the proportion of rainfall in that is getting even larger.



This holds across Australia so you can expect that this change is universal. And it's a mechanism nobody has really looked at until now.



MANDIE SAMI: So what does it mean?



ASHISH SHARMA: This is the first study in the world, to our knowledge at least, that looks at what will happen within an individual storm.



And it's finding that what will happen will increase flooding on top of what was expected.



MANDIE SAMI: Professor Sharma says with just a five degree Celsius temperature rise the flood peaks could increase by an average of five to 20 per cent for a typical medium-sized catchment.



He says the results show how important it is for councils to think about redesigning sewerage and road infrastructure and even updating guidelines about where it's safe to build homes.



ASHISH SHARMA: If you see during a heavy downpour water covering the street for say 10, 15, 20 metres at a stretch, that 10, 15, 20 metres might become 30 metres because you will have that extra flooding.



And the storms can only take that much amount of water so unless you fix the sewers, and the storm drainage network up, you will have problems.



MICHAEL BRISSENDEN: Professor Ashish Sharma from the University of New South Wales, ending Mandie Sami's report.