Saturday, June 13, 2015

Flash flood risks increase as storm peak downpours intensify

EurekAlert via the University of New South Wales: Patterns of peak rainfall during storms will intensify as the climate changes and temperatures warm, leading to increased flash flood risks in Australia's urban catchments, new UNSW Australia research suggests.

Civil engineers from the UNSW Water Research Centre have analysed close to 40,000 storms across Australia spanning 30 years and have found warming temperatures are dramatically disrupting rainfall patterns, even within storm events.

Essentially, the most intense downpours are getting more extreme at warmer temperatures, dumping larger volumes of water over less time, while the least intense periods of precipitation are getting weaker. If this trend continues with future warming, the risk of flooding due to short-term extreme bursts of rainfall could increase even if the overall volume of rain during storms remains the same. The findings were published today in the journal Nature Geoscience.

"These more intense patterns are leading to more destructive storms, which can significantly influence the severity of flood flows," says lead author and PhD candidate Conrad Wasko, from the UNSW School of Civil and Environmental Engineering. "The climate zones we studied in Australia are representative of most global climates, so it's very likely these same trends will be observed around the world."

Previous studies have looked at rainfall volumes over the total duration of storms, but this latest UNSW study is the first to look at temporal rainfall patterns within storms. Australian Bureau of Meteorology data from 79 locations across the country were used instead of computer simulations....

Photo by Shootthedevgru,Wikimedia Commons, under the Creative Commons Attribution-Share Alike 3.0 Unported license

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