- Thursday 01 March 2012
The term "the rain is bucketing down" has taken on new meaning here on the Coast since last Friday.
Sunshine Coast Council has released facts on the recent rainfall which show why the downpours have created so much damage across the region.
Local Disaster Co-ordinator Fox Rogers said the amount of water that fell in last Friday night's storms has exceeded previous records for hourly and three hourly rainfalls.
"In one three-hour period enough rain fell over Cooroy, Pomona and Cooran to create a 30-centimetre deep – or one-foot-deep – lake, with Noosa Heads and Tewantin similarly affected," Mr Rogers said.
"Council’s drainage and road systems can handle heavy falls of about 15 centimetres but this event was more than double that.
"To put it another way: in Friday’s storm enough rain was falling to fill a nine-litre bucket in three hours and because this rain was running off and compounding, the bucket of water rapidly became a full wheelbarrow, then a full tank, then a swimming pool-full over a very short distance."
This is the essence of flash-flooding and when it occurs the power and the energy of water means it determines its own flow path, Mr Rogers said.
"Cooroy received a real bucketing - 182 mm in one hour and this resulted in Lake McDonald reaching its highest level since the dam wall was raised 30 years ago," he said.
"That’s an incredible amount of rain, and it fell on ground already saturated by previous storms.
"It was not only people living near rivers and creeks that were having problems on Friday night. Such was the intensity of the rainfall, we were getting calls from people living on the tops of hills who were having water flow through their houses.
"On that night the SES was called out to more than 180 jobs and there were 35 swift-water incidents involving the police and fire brigade – a number of which were life-threatening."
Mr Rogers said La Nina weather conditions, which increase precipitation over a number of years, had been missing for a long time, and had returned.
"The rain we have seen the last couple of years has been reminiscent of that which older members of the community will recall as ‘normal’ in the seventies," he said.