Cities will be more vulnerable to flash floods as climate change intensifies storms, creating narrower and more concentrated downpours, according to an Australian study.

The report by University of NSW engineers Conrad Wasko and Ashish Sharma shows the first evidence of intensification triggering more destructive storm patterns.

“As warming proceeds, storms are shrinking in space and in time,” Mr Wasko says.

“They are becoming more concentrated over a smaller area, and the rainfall is coming down more plentifully and with more intensity over a shorter period of time.”

Mr Sharma says most urban centres have old stormwater infrastructure that is no longer adequate.

“Look at the incidents of flooding in Mumbai or in Bangkok last year – you see urban streets full of water,” Mr Sharma says. “You see it now in Jakarta and Rome and many parts of Canada. That’s because the stormwater infrastructure cannot handle the rain, and part of the reason there’s more rain is the increase in global temperatures.”

Compared with rural regions, urban areas have less soil to absorb water, and drainage capacity is overwhelmed.

Mr Wasko, Mr Sharma and academics from the University of Adelaide analysed data from 1300 rain gauges and 1700 temperature stations across Australia.

Despite the data being local, the results have global relevance, given Australia spans almost all climate zones, Mr Sharma says.

In a study last year Mr Sharma and Mr Wasko calculated floods in some parts of Australia would likely increase 40%, especially in warmer places such as Darwin.

“If you add the spatial pattern from this latest paper, you will probably increase this 40% number to maybe 60%,” Mr Sharma says.