Last December, Melbourne braced itself for the “super storm”, when about “a summer’s worth of rain in just a 24-hour period” would fall, according to the Victorian Premier Daniel Andrews. Predictions of flooding were rife, as up to 100mm of rain hit the city in a day. This, however, is small change to Queenslanders looking at the news reports from afar.
“We had someone up from Melbourne and they were discussing the super storm and I was laughing – because 100mm wouldn’t really touch the flood-proofing we’ve got up in Queensland,” says Graeme Harvison, landscape architect at Tract.
Harvison worked with a team to renew the University of Queensland’s rectangular sports field, which was inundated during the 2011 floods. As a result synthetic fields were constructed on a raised platform. “The university realised that the fields sit in an area that is subject to high levels of flooding, so they had to rebuild with ongoing maintenance and condition factors in mind,” he says. “So the question was, what level do you have to raise them, to provide flood immunity”.
Coastal Risk Australia estimates that the worst-case sea-level rise scenario will be up to 2.7 metres by 2100. This is a significant increase on previous estimates, and means that most low-lying areas within Australia’s capital cities will be at risk. And of course, for universities with plenty of vulnerable assets, flood-proofing property in-line with updated metrics will have to be an ongoing concern.
For UQ, this meant raising the sports field up one storey, providing space for 500 car spaces and 350 bike racks below. Beyond practical benefits for the end-user, the fields also integrate resilient storm-water drainage channels, in preparation for this century’s well-documented predictions of more intense, and more frequent storm events.
“On the southern side of the site, there’s a lake that rainwater can flow into which will fill up in the event of a storm. That water then gets diverted to a bio-retention system in an adjacent garden which eventually flows into the river.” Though, with a once-in-100 year flood event (known as a Q100) predicted to happen by one percent every year, the design of these grounds are also designed to respond to climactic extremities.
“There’s an acceptance that the carpark will flood in the event of a Q100, because it’s just a fact of life now,” says Harvison. “After the 1974 floods, pundits said the Wivenhoe Dam would always protect Brisbane – that was made a mockery of during the 2011 floods. So because we know that water will flood into the carpark, that meant we designed it so that water could escape out of those spaces, utilising swales to push the water around.”
“The fields are designed in a way where water sheds off towards edges in a storm event, that eventually spill over the edges during a storm surge. This works with a swale sitting between the two fields, coming together to form a pretty significant drainage system.”
And of course, in a tropical city like Brisbane, sea-level rise coinciding with storm surge events will continue to be the norm, rather than the exception to the rule.
“And we’ve also got to think about inundation periods, because I think sometimes people think that sea-level rise will swell to a certain level and stay there. The real question is thinking about how many times the sea will hit that height within a certain period of time.”
With billions of dollars being invested in university campuses every year, mostly on new expensive iconic buildings, parks and public space, there is no doubt that this example at UQ represents only the start of a much larger trend: to manage future flood and inundation. Over time we will see universities investing time, research and money into managing the impacts of major water events in the years to come.
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