Water is the key to sustainability

Fresh water and its effect on sustainable food production will be a key determinant of future social wellbeing, globally and nationally.

But the water available to grow the world's food could shrink because of the decline in groundwater resources, burgeoning demand from cities and the effect of climate change on food producing regions.

It is in this context of an agriculturally water-scarce world that Australia has to seriously rethink its approach. The condition of the Murray-Darling basin and other key water resources, as well as the effect of the 10-year drought on much of southern Australia, has accentuated our own vulnerability.

However, Australia has one tremendous advantage: because we have a water-scarce environment, we focus on this issue more than most other countries.

But we still have a problem.

• Few Australians are aware of the fate of water when it hits our landscape. On average, of every 100 drops of rain that fall:
• Thirty drops are absorbed and transpired by vegetation and crops.
• Six drops are added to groundwater.
• Twelve drops enter our creeks and rivers (of which two are lost and four flow to the sea).
• Two drops enter our dams and storages, of which:
• 1.6 drops grow our food.
• One-third of a drop is used by industry.
• One-tenth of a drop is used in our homes, parks, ovals and for other uses.
• A massive 50 drops out of the 100 wastefully evaporate.

The most striking aspect of this national water budget is that 50 per cent is lost through evaporation. How much more water-rich this country would be if we could harvest and re-use even a tiny part of this lost water.

We know from temperature and rainfall records that our climate is becoming hotter, drier and less predictable, particularly in the south. As more of the continent dries out, there will be less vegetation to help water enter our soils as well as increased evaporative losses. We also know from scientific research there have been savage drying cycles in the past 100,000 years, in which the landscape was stripped of trees and sand dunes rolled to the sea on three of our four coastlines, so we have some warning about how dry this place can get.

Knowing this, we are in the privileged position of being able to do something about it, as thousands of farmers already are: rehydrating the landscape through careful management of soils, water and vegetation. At individual farm level many farmers are showing that it is possible to increase soil moisture retention, soil fertility (carbon) and vegetative cover, either crops, pastures or native species.

Just as we store water in dams for later use, or start to recharge aquifers, it is time to consider a national effort to increase water storage within the landscape. Our dams store only two raindrops of every 100 that fall; our landscape can, potentially, store 10 times or more of those raindrops.

For example, with advice from Peter Andrews, who devised the natural sequence farming approach, Tony Coote, near Bungendore, NSW, is reconstructing his creek so it performs more like an Australian chain of wetlands rather than an incised European river that carries all the water away. His goal is to change the at-risk landscape to re-create conditions seen in photographs and records from the 19th century. Then, green grass flourished through summer thanks to the natural water-retaining capacity of the flood plain before Europeans changed the landscape and its hydrology through over-use of the axe.

Comparable approaches are being pioneered by farmers from the West Australian wheatbelt to the grazing and cropping country of central Queensland.