Describing a severe weather event as a "one-in-100-year flood" is misleading and the term should be dropped, a Queensland academic says.
The term doesn't mean a flood will occur once in 100 years, but that there's a one per cent chance of a flood happening in any given year, said Associate Professor Dann Mallet, from the Faculty of Science and Technology at the Queensland University of Technology.
Professor Mallett said the term was confusing and might mean that people do not take the necessary precautions against flooding.
"They may think there is no longer any need to worry as we have already had our one flood in 100 years," he said.
"But as we have seen with the current devastating floods, there is no guarantee that the next damaging flood will take 100 years to arrive."
Professor Mallet said authorities and media needed to refer to the floods differently.
"The one in 100 years term has been grabbed from mathematics and risk analysis and used inappropriately, and now I think the scientific community should be making it clear there is a 1 per cent chance it could happen in any given year," he said.
He said extensive flooding last year could have convinced people there was no such danger this year.
"The fact is that we are not at any lesser risk of flooding in 2011 because of the floods we have had in the past year, and it is important people are aware of that."
Professor Mallet said that, due to the misunderstanding, people might not heed the advice of police, meteorologists or other authorities giving out flood warnings, and might not prepare or protect themselves adequately.
"Although you may have a one in a million chance of winning a lottery, most people never win, but some people win twice - there are no guarantees," he said.
"In the same way, we have seen our state devastated by 100-year flood events twice in the space of just 12 months."