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The flooding in Dunedin on Wednesday was not caused by climate change, a University of Otago climatologist says.
''I think this is just a weather event,'' Dr Nicolas Cullen, of the department of geography, said.
The Green Party and Dunedin Mayor Dave Cull have been quick to link the downpour to climate change.
Dr Cullen cited a 1929 downpour of 220mm within 24 hours, and estimated Wednesday was a one-in-30-year event.
''This particular event is more related just to the weather patterns that developed over the period which allowed that frontal system to really hit Dunedin quite hard.''
The MetService reported Dunedin received 175mm in the 24 hours to 4am yesterday, with heavy rain continuous in the city for 17 of those hours.
''You tell me. It's wrong,'' Dr Cullen said when asked why it was called a 100-year event by the Dunedin City Council.
''I wouldn't put this in the climate change basket too quickly.''
If the same rainfall happened every month for a year ''then we can start talking about climate change''.
The flood did, however, demonstrate the city's potential vulnerability to sea level rise, he said.
Dunedin hydrologist Dave Stewart said his initial estimate of Wednesday's flood was a one in 30-to-50 year event.
He had not had time to analyse the data, but rainfall at various sites ranged from 140mm to 180mm.
Mr Stewart was scathing about the DCC's 100-year claim, saying he did not know how it arrived at the estimate.
He also dismissed the idea the event was linked with climate change.
Mr Stewart said the stormwater system could not have been expected to cope with the deluge.
Upgrading it to cope with more than a one-in-10-year event would require a massive investment and rates hike.