WATER IN THE FUTURE

Just as issues around water have moulded much of Australia's past, they will also influence the future. Several issues threaten to impact strongly on water resources and urban supplies in Australia in the future. These include climate change due to global warming, salinity and environmental degradation generally.

Increasingly, communities are asking questions about basic quality of life issues, such as their water supply. They have a right to ask these questions, and to expect answers, just as they have a right to expect the drinking water available to their children to be safe and pleasant.

The needs of the population in the next 30 to 50 years are uncertain. Demand management programs will help to halt the previous trend of increasing per-capita consumption.

The optimum population of Australia has been the subject of speculation and debate by governments, academics and the community for decades. In recent times, the term ecologically sustainable development has been used when estimating limiting conditions on population growth. Issues such as the impact of increasing urban development on the environment and on quality of life need to be included in those discussions.

Water supply, use and disposal did not undergo major technological changes in the last century: there were no paradigm shifts in relation to technology of water management. In the 21^st century, technology is likely to provide much more change for the water supply industry.

Increased use of water-efficient appliances by urban consumers will play a part in achieving ecologically sustainable development. A water-efficient appliance is one that has water conservation as one of its design criteria. It uses or enables the use of water more efficiently.

Water-efficient appliances generally do not rely on attitudes or behaviour of the user; rather, they impose responsible water use on the user. Savings from water-efficient appliances take time, because they are introduced slowly, replacing existing appliances. However, the water-efficient appliances being promoted at this time are expected to lead to a significant fall in per capita water use over the next couple of decades.

According to CSIRO's latest climate change estimates, Australia will become hotter and drier in coming decades. Warmer conditions will produce more extremely hot days and fewer cold days. CSIRO scientists estimate that over most of the continent, average temperatures will be 0.4 to two degrees C greater in 2030 than 1990. By 2070, average temperatures are likely to increase one to six degrees C. These temperature ranges reflect the scientific uncertainty associated with the projections.

CSIRO climate projections indicate that the warming won’t be the same everywhere, with slightly less warming in some coastal areas and Tasmania, and slightly more warming in the north-west.

South-western Australia can expect decreases in rainfall, as can parts of south-eastern Australia and Queensland. Wetter conditions are possible in northern and eastern Australia in summer and inland Australia in autumn.

In areas that experience little change or an increase in average rainfall, more frequent or heavier downpours are likely. Conversely, more dry spells are likely in regions where average rainfall decreases.

Evaporation is expected to increase over most of the country. When combined with expected changes in rainfall, there will be a clear decrease in available moisture across the country.

Governments and water authorities have to consider climate change now in planning water supplies for the future.

Significant deforestation has occurred in Australia since British colonisation in 1788. One result of this change in vegetative cover, affecting transpiration rates from forests, has been a reduction in rainfall in some catchments. Another has been salinity. A wide understanding of the need to reverse previous land management practices now exists, but in some areas it may be too late.

Across the country we need to find a meaningful balance between the competing demands for water of agriculture, urban consumption, and ecosystems.

One action to help achieve this balance was the establishment by the Federal Government of the National Land and Water Resources Audit. The Audit recently produced Australian Water Resources Assessment 2000 - surface and groundwater availability and quality, the first comprehensive national audit of Australia’s surface water and groundwater resources covering both water quantity and water quality.

The Audit reveals that, on average, Australia's water use has increased 65 per cent since the early 1980s.

Using the best available information provided by state and territory agencies, the Audit shows that 26 per cent of Australia’s surface water management areas are approaching or beyond sustainable extraction limits and that 34 per cent of Australia’s groundwater management units are approaching or beyond sustainable extraction limits.

Changes to the Australian landscape, and in particular tree clearing, have resulted in the widespread and rapidly growing problem of salinity. While naturally occurring salinity is part of the Australian landscape, human impacts have upset the previously existing balance.

The problem has developed slowly. With the removal of the natural vegetation, the amount of water entering the water table (called the recharge) has increased and the rising groundwater level has dissolved the accumulated salt within the soil. Eventually, and perhaps more than 100 years later, the groundwater level reaches the surface, bringing the salt with it. This results in the death of all but the most salt-tolerant plants with consequential changes to other parts of the ecosystem.

While farmers were among the first to be affected, through salt-affected agricultural land, the impact on sources of freshwater has also been of growing significance.

Biodiversity, as well as regional and urban infrastructure, such as water supply, roads and buildings are now also at risk.

Just as it has taken a long time to appreciate the scale of the environmental degradation, the timeframe for these changes to be slowed or reversed will also be considerable.

The cost of the problem to the wider Australian community will be huge.

According to a statement issued by the Prime Minister in October 2000 at the launch of the National Action Plan for Salinity and Water Quality in Australia, salinity and water quality problems were critical and demanded urgent attention. Among the problems detailed by the Prime Minister were:

• One-third of Australian rivers are in an extremely poor condition.
• Adelaide’s drinking water is likely to fail World Health Organization salinity standards in two days out of five within 20 years.
• Land and water degradation, excluding weeds and pests, is costing up to $3.5 billion a year.