Direct reuse could reduce flood risks says researcher
Use of direct potable reuse (DPR) of wastewater could have saved the Australian city of Brisbane from severe flooding in 2011 and mitigated recent flood risks in the state of New South Wales (NSW), according to an environmental engineer at the University of New South Wales.Dr Stuart Khan of the Water Research Centre said on 12 April 2012 that DPR could free up millions of cubic metres of water from reservoirs around Australia, giving cities a greater buffer to capture rainwater and control major flooding events.
With DPR, highly treated wastewater is introduced directly to drinking water treatment plants, without re-entering the natural environment along the way. In Queensland alone, DPR would be the equivalent of immediately constructing a new 425 million m³ reservoir, without the cost of construction or having to relocate a single home or farm, says Khan.
Khan's research shows that this added 'virtual' storage space would represent a 30% increase on the volume currently reserved for flood mitigation in this regions.
"DPR probably would have saved Brisbane from the 2011 floods from Wivenhoe," he says. "The big inflow peak of around 1,900 million m³ that occurred between 9 and 13 January 2011 could have been contained in the dam, rather than spilled."
DPR could also have mitigated recent floods in NSW, Khan says. For example, it would have enabled Warragamba dam to have been managed with an available "flood control volume", without compromising the security of future water supply.
"Other dams that have spilled recently should be closely investigated for opportunities to increase the flood control capacity in the future," he says.
Khan points out that this type of water recycling also has several environmental benefits compared with indirect potable reuse.
"DPR can mean a reduced need for pumping water, reduced operational costs, reduced energy consumption and a lower carbon footprint," says Dr Khan.
DPR would also provide an invaluable supply of emergency drinking water in the event that reservoir water quality is compromised, as sometimes happens after high rainfall events, algal blooms and bushfires.