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Acoustic Doppler Velocimeter gathers first data on Queensland floods

Future emergency flood management and building design could benefit from the quick thinking of a QUT fluid mechanics researcher who gathered what’s believed to be the world’s first data on water velocity and sediment concentration in flooded buildings.

Associate Professor Richard Brown from Queensland University of Technology’s School of Engineering Systems, found being inside a building was no protection against water strong enough to knock people off their feet, during the Brisbane floods.

"We had an ADV or Acoustic Doppler Velocimeter on-hand at QUT which measures water velocity and sediment concentration so we thought ‘why not install it in the carpark?’ and try and learn something for the future," said Brown.

He is still analysing data from a flood monitoring station he and his team installed in the car park of C Block at QUT’s Gardens Point campus, about 100m from the overflowing Brisbane River. The device collected data for 48 hours. During this time it had to contend with debris including wheelie bins and logs.

"We were surprised at how dangerous it was – the most stunning finding was the sudden changes in velocity. Our analysed results will be useful for future disaster planning," said Professor Brown, who had to use a safety rope while installing the device in the flooded car park with a depth of more than one metre of water.

"We found the water could be flowing at 0.3 metres/second – a rate at which an average person can still stand up -but within 40 seconds it could surge to 1.8metres/second – which is so swift and strong it would knock a person over.

"Added to this finding is the fact that the strength of surging floodwaters in buildings is exacerbated by smooth floors which offer no resistance or interruption to the flow."

Professor Brown said such data was difficult to collect because of the unpredictable nature of floods and the logistical difficulties that accompanied them.

"The aim was to gain a better understanding of the behaviour of flood waters in urban areas. These findings will be of use to urban planners, building designers and engineers, flood modellers and of course, disaster management planners," he said.

"This sort of information will assist architects and designers to build safer buildings with railings, places of refuge or ways to slow water flow."

Professor Brown worked with fellow researchers Dr Jai Madhani and Dave McIntosh from QUT and Professor Hubert Chanson from University of Queensland to analyse the data collected by the monitoring station.

"As far as we know, no one has thought about how floods surge in a building," said Brown.

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