WATER

By Professor Richard Kingsford
Australian Wetlands and Rivers Centre

Humans are appropriating more of the world’s freshwater than ever. We can’t do without it. And with more than 200,000 of us added to the planet every day, we need more water because we need to drink, eat and be clothed.

Given that more than half our body weight is water, we don’t last long without it. Perhaps a less obvious dependency is our reliance on water for much of our food and clothing. Many agricultural crops, such as rice, cotton, citrus fruits and grapes, require fresh water diverted for irrigation from rivers, groundwater or wetlands for their growth.

Even many dairy cows feed on irrigated pastures in parts of southern Australia to provide us with milk. Feed lots for livestock are also notorious heavy users of water with the average hamburger requiring more than 2000 litres of water in its production.

Much of our energy production is also tied to water use. Coal-fired power stations use large quantities of water to generate steam that drives the turbines. Even hydroelectricity generation, often seen as a more sustainable and cleaner way of generating energy compared to coal-fired power stations, requires the building of dams which changes the flow regimes of rivers and affects their ecology. These drivers exist across the globe but the extent of development is highly dependent on the resources of a particular country or even access to water.

Australia’s water use reflects growth not only in the country’s population but also the world population. Every one of our major cities -- Adelaide, Brisbane, Perth, Melbourne and Sydney -- has experienced considerable concerns about water shortages, particularly during the last prolonged dry period. With Australian populations predicted to potentially rise to 35 million by 2050, there will be more pressure for access to water. This will either require the building of more dams and diversion of water or other sources of supply such as desalination plants or stormwater harvesting.

In 2006, on a per capita basis, Australia was ranked third highest user of water in the world. While about one sixth of the world’s population does not have access to safe drinking water, we use about 220 litres per person per day compared to the average 50 litres of an African. Much of our water use supports irrigated agriculture, concentrated in the Murray-Darling Basin, which accounts for between 60 and 70 percent of all Australia’s water use.

Food security for world populations will inevitably be considered a prime driver for water resource development in Australia, given that we export commodities such as cotton, rice and vegetables. There is likely to be increased pressure to develop water resources in northern Australia for agricultural use.

The ecological consequences of water resource development are now well known around the world. Taking water from rivers affects ecosystems, particularly dependent wetlands and estuaries. The degradation of many of the protected wetlands in the Murray-Darling Basin is primarily due to the over-allocation of water resources from rivers. This was particularly acute during the long dry period experienced across eastern Australia recently. The symptoms of this degradation include declining waterbird populations, dying floodplain eucalypt trees such as river red gums, increasing salinity and increasing incidences and extent of blue green algal blooms. The Australian Government is now addressing this through the buyback of water for the rivers to increase environmental flows.

Our management of water resources to meet human needs and those of the environment are further challenged by climate change. Higher temperatures increase evaporation from storages and reduce the duration of flooding in wetlands, which potentially reduces the amount of time for different organisms to complete their life cycles. There is also increasing evidence that rainfall patterns will be more variable and possibly reduced in southeast and southwest Australia. If current trends in rainfall reflect impacts of climate change, there will be severe impacts on urban and irrigation communities as well as the dependent ecosystems.

The future challenge will be to do more with less water across urban and rural Australia if we are not to continue to impact seriously on the sustainability of dependent ecosystems. We need to capture more water from our city catchments for our use and reduce the amount of water we use in irrigated agriculture while maximising our production.

WATER

On the vexed issue of water supplies, environmental scientist Professor Richard Kingsford says every major Australia city already has concerns about water shortages. The future challenge will be to do more with less water across urban and rural Australia.

See also:

"Australia is ranked third highest user of water in the world."