A leading water scientist has proposed the development of a National Water Bank – a continent-wide replenishment scheme for underground reserves of fresh water – to help safeguard the nation from water scarcities for centuries to come.
The creation of a National Water Bank, a vast monitored network of 'underground dams', could do much to help Australia avoid future water shortages, says Professor Craig Simmons, the Director of the National Centre for Groundwater Research and Training.
"The Australian Government has recognised the vital importance of having enough water to underpin our national economic future and anticipated population growth – and has set up a Ministerial Working Group to oversee it. Our proposal for a National Water Bank is intended to contribute to this process," Prof. Simmons says.
"Groundwater accounts for 95 per cent of Australia's available fresh water. It is a vital reserve for agriculture, mining, manufacturing and urban use and supports industry worth $34 billion. If we look after it, it will look after us - for all our foreseeable future," he says.
Professor Simmons says a National Water Bank would help by ensuring the nation's aquifers were recharged during times of plentiful rainfall and then monitoring the water balance of both surface and underground water to ensure adequate future supplies for industry, cities and the environment.
"Potentially, this could be among the nation's most farsighted infrastructure projects, on a par with the Sydney Harbour Bridge or Snowy Mountains Hydro Scheme.
"Underground dams have two big advantages over surface dams – first, they lose little of their water to evaporation and second, they are cheaper to build. Instead of vast earthworks and flooded valleys, you just need a few pumps or soaks to inject water at the right time into carefully-researched aquifers. That water can then generally be recovered at need."
The storage ability of a National Water Bank lies in relatively lower-cost items like infiltration ponds, injection bores, computer models and sensors rather than in very costly earthworks and concrete associated with major dams and reservoirs costing hundreds of millions of dollars: if the amount of water being stored and discharged from an aquifer is known, it can always be managed sustainably, Prof. Simmons says.
"Like a financial bank balance, the idea of a National Water Bank means being able to know, at any given time, how much you have on hand, and what are your deposits and withdrawals.
"It is vital we better understand our national groundwater storage capacity, its recharge rates, and the potential for us to augment and top up our aquifers with artificial recharge," Prof. Simmons says.
The idea of a National Water Bank received fresh impetus from the fifth report of Intergovernmental Panel on Climate Change (IPCC) last month. This warned "Climate change will affect groundwater (in Australia) through changes in recharge rates and the relationship between surface waters and aquifers. Dryland diffuse recharge in most of western, central and southern Australia is projected to decrease because of the decline in precipitation, with increases in the north and some parts of the east because of projected increase in extreme rainfall intensity."
The report indicates that rainfall in south eastern Australia could decline by up to 40 per cent and in south western Australia by as much as 70 per cent over the coming three to four decades. This in turn will lead to massive reductions of water flowing in surface rivers and streams. Typically a decline in Australian rainfall is amplified 2–3 times in terms of what is in surface flows, the IPCC cautions. This will be accompanied by increases in evaporation due to warmer days, and the prospect of more frequent, fiercer droughts – interspersed by episodes of more intense rainfall and flooding.
"This serves to remind us of the importance of developing and implementing a national action plan for fresh water in Australia – one that has increased emphasis on groundwater, reflecting its importance as the nation's primary natural water bank," Prof. Simmons says. "It emphasises the need to stock up on water as soon as possible – rather than waiting for our groundwater reserves to become depleted by the next big drought."
He adds that a National Water Bank can outlast many existing projects and structures by centuries and can potentially benefit the whole continent, not just particular regions. "It can cushion Australia, its vital industries and regions against climate unpredictability. It can help protect and regenerate our native landscapes and greatly improve our national water security. And it can be achieved for much less than the cost of building a network of surface storages across Australia.
"All we need to do to achieve this is invest wisely in the necessary science, technology and management skills. Water science and training are not high cost items, relative to other activities like building huge dams or ports. They represent a form of 'infrastructure' that lasts for generations and only needs topping up, not repair. They pay off immediately in water savings and help keep water prices low for everyone. They provide insurance against drought, climate change, and the loss of water-dependent industries, towns and landscapes. They can reduce the economic and social costs of drought greatly."
Prof. Simmons adds that the opportunity to build a National Water Bank will put Australia in the front rank of the world's wise water managers at a time of looming global water scarcity – leading to major new knowledge exports in water management and technology. "So it will create jobs and exports as well as preserve our most precious resource – fresh water," he says.
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More information: The IPCC assessment is available online: ipcc-wg2.gov/AR5/images/upload… R5-Chap25_FGDall.pdf