Can we see the water for the storm?

Posted Jul 30, 2008 9:30pm

As we continue to shorten our showers and tighten our taps, Brisbane and southeast Queensland have of late endured localised flooding.

Had you driven down any Brisbane street in the past few weeks, you would have seen a river of the new gold gushing its way past our homes and businesses and into the abyss.

In Brisbane City alone, there are more than 2000kms of enclosed urban stormwater drains and some 10,000km of kerb and channel stormwater drainage.

Just the place for an urban water catchment area according to Dalby based environmental researcher and consultant Dr Peter Wylie.

“If one quarter of Brisbane’s stormwater runoff could be captured, it would supply in the vicinity of one third of the total water demand,” he says.

Wylie heads the Dalby based Horizon Rural Management and has spent years researching environmental issues including water, energy, climate change and sustainable farming.

“There is more than 30,000 hectares of concrete, bitumen and buildings in the greater Brisbane area. The annual runoff from this area, with 1000 millimetres of rain, is 300,000 mega litres. This is in excess of the annual use of water in the Brisbane area of 280,000 mega litres,” he says.

As public debate continues surrounding alternative water management practices, Wylie said Brisbane needs to diversify into more reliable water supply options.

He cites Newcastle, Canberra and Adelaide as Australian cities that have taken the next step in capturing and utilising stormwater runoff, at a cost which is cheaper than constructing large dams.

“Brisbane should use its own water supplies before moving further out into the countryside to take away water supplies from rural residents and farmers,” Wylie says.

Wylie believes much more could be done to enhance existing stormwater systems, to store water underground and to treat it with reverse osmosis for urban use.

“A classic example of underground water storage is on the Gold Coast, where thousands of spear pumps reclaim rainwater, which has percolated through the sandy soil,” he says.

“In Brisbane, soils are generally less suited to percolation, but stormwater from buildings and roads never gets a chance to be stored underground, because it is channelled away into concrete drains and pipes very quickly.”

He says one potential underground water storage facility lies just north of Brisbane in the Nambour Basin. It runs from the mouth of the North Pine River to the mouth of the Maroochy. He says geological estimates are it should contain approximately 18 times the total capacity of Brisbane’s three main dams.

“It should be possible to recharge this with stormwater from the northern side of Brisbane,” Wylie says.

Stormwater harvesting is not a new concept, yet for reasons such as cost, viability and purity, it seems to have in the main slipped under the radar of the recent water debate.

While acknowledging its potential, some experts feel research is required before stormwater can seriously be viewed through the prism of public water infrastructure.

One such expert is SEQ Water Operations Manager, Rob Drury.

“It would be very difficult logistically, on a large urban scale especially, to capture, store and re-use the volume and quality of water required,” Drury says.

“To capture, store, purify and reuse urban stormwater is a major task as the flows are high in volume and of short duration. The pollutants in urban runoff can also be considerable, considering the urbanised area that is the catchment.”

Among other tasks, SEQ Water is responsible for the management and monitoring of the regions dams and Drury says these traditional storage facilities will remain the better option at least in the near future.

“To be able to collect water runoff in urban areas is quite difficult. It is often a poorer quality than what we can collect in our dams. Overall it is the storage and quality issues that need to be addressed,” he says.

“That’s not to say we shouldn’t consider it and there is in fact research into this area underway at the moment.”

Such areas of research are the focal point of the Institute for Sustainable Futures at the University of Technology, Sydney.

Institute head and co-author of the recent report into the Queensland government’s proposed dam at Traveston Crossing, Professor Stuart White, says stormwater harvesting certainly has a role to play.

“Stormwater capture and its use is a must in new and renewal developments,” White says.

“It is definitely a possibility but as a community we must first implement efficiency measures that enable the maximisation of our existing water resources.”

It is this maximisation of resources and its consequent responsibility that underpins what Wylie is calling for.

“What is needed is some determined investigation and commitment of money from all levels of government to tap into the most vital resource of all, the rain which falls on Brisbane.”

Related Links

• Institute of Sustainable Futures