As humans are unable to survive for more than a few days without fresh drinking water, it is our most important natural resource. A major concern both within Australia and around the globe is that demand for water currently exceeds supply, and more than a billion people on Earth already lack access to fresh drinking water. Rainfall patterns and the location of river basins naturally determine the settlement patterns of humans. In Australia, which has one of the highest levels of per capita water consumption in the world, water availability has played a key role in where our towns and cities have been built. Australia's largest river system is the Murray-Darling, which stretches from southern Queensland (Qld) to the Coorong Wetlands in South Australia (SA). It is no surprise, therefore, that the south-eastern area of Australia is the most densely populated.
In addition to the consumption needs of humans and wildlife, water is also essential for the development of industry, agriculture and recreation. Irrigated agriculture accounts for the majority of our water use (around 75 per cent) in Australia, with the remainder utilised for industrial and recreational purposes (20 per cent) and household purposes (5 per cent). The way we manage our sources of water should be considered as closely related to the way we manage the land. Reducing water consumption and developing improved systems of land management are two fundamental ways in which we can improve upon the way we utilise water as a resource.
Major sources of water in Australia
Rainfall is the ultimate determinant of water availability. In Australia it divides the continent into two regions: the moist periphery and the arid (dry) centre. There are two main sources of water in Australia: surface water (the biggest provider) and ground water. Most water from our natural sources is impure and therefore needs to be treated before it is safe to drink or use on crops.
The Murray-Darling river system is one of Australia's most important sources of fresh surface water. Approximately three million Australians in SA, Victoria, the Australian Capital Territory and New South Wales (NSW) are dependent on it for their water needs. Approximately 3750 km in length, it is the fourth largest river system in the world. Even though its large basin covers 14 per cent of mainland Australia, the Murray-Darling actually holds a relatively small amount of water.
The largest supply of ground water in Australia is found in the Great Artesian Basin, which extends under approximately 22 per cent of the mainland (spanning an area of 1.7 million km sq), mainly in Qld and NSW, but also under parts of the Northern Territory and SA. It is three kilometres deep, and is a major source of water for towns, farms and industry in the surrounding areas.
Major water management problems
The mismanagement of water over the past two centuries has severely depleted water supply and degraded water quality in Australia. Scarcity, salinity, damming and pollution are the key areas of concern regarding water management.
Australia is the world's driest inhabited continent. Water availability (or lack thereof) is currently a pressing concern. Extremely variable rainfall patterns in the arid centre lead to Australia's cycle of droughts and floods, which have become more extreme with increased human impact since European settlement. Low rainfalls in the wetter periphery region, where the majority of the population resides, are also a major concern. In Sydney, for example, inflows into Warragamba Dam have been below average for the past ten years and the city's eleven dams are often below capacity. Added to the problem of low rainfall is the issue of evaporation. Due to Australia's extremely warm climate, all but 13 per cent of rain that does fall across Australia evaporates before it ends up flowing into rivers. See image 1
Apart from depleting water supplies, salinity is undoubtedly the biggest problem affecting the management of water resources in Australia. The alarmingly high and rising level of salt found in our water is related to the problems of dryland and irrigation salinity discussed previously. Since Europeans arrived over two centuries ago, massive areas of vegetation have been cleared in order to create pastures, grow crops and harvest timber. This has meant that when it rains, water tables rise and bring with them salts naturally located deep beneath the surface of the ground. This salt then flows back into the rivers during periods of heavy rain, often rendering the water useless (or at least unsafe) for users further downstream. The problem of saline water (water high in salt content) is particularly evident in Adelaide, where water drawn from the Murray-Darling River system has struggled to meet World Health Organisation standards for potable (drinkable) water in recent years. See image 2
A common approach to water use and management in Australia, and indeed around the world, has been attempting to increase water supplies for human consumption through the creation of dams which hold a large amount of water. This solution has had both positive and negative consequences. The construction of dams (such as Warragamba Dam in Sydney, which holds approximately two million mega litres of water and Tomson Dam in Melbourne, which holds about half of this) disrupts the natural properties of water. It also disrupts the flow of water through our river systems and results in a loss of forests and wildlife in surrounding areas. This in turn reduces the biodiversity (range of plant and animal life) of waterways. An alternative to the construction of large dams like Warragamba Dam are smaller hydro-electric plants, which have less impact on the environment. They can also be used to generate hydroelectric power, a renewable source of energy, which can replace damaging greenhouse gas-emitting sources driven by fossil fuels.
Runoff from fertilisers used for agricultural purposes, along with sewage effluent and chemical pollutants from domestic and industrial areas, severely pollutes the water we depend on for survival. Sometimes it leads to the formation of toxic algal blooms (large populations of blue-green algae) in our river systems and wetlands. This problem occurs when algae use contaminated runoffs as a nutrient, which help them flourish. When the algae spread they can become toxic to humans, plants and animals. Australia was notorious for recording the world's largest algal bloom in the early 1990s. It stretched for 1000 km across the Barwon and Darling Rivers in NSW. See image 3 and animation 1
Certain types of introduced animal species, such as the European and American trout, have damaged Australia's waterways and started to dominate native freshwater fauna. Some problematic introduced plant species, such as the water hyacinth, have also transformed into weed populations and are currently devastating many of our rivers and lakes. As well as blocking waterways, these weeds form dense layers on the surface of the water. This prevents much-needed sunlight from reaching deep-rooted plants that grow under the water. This can potentially decrease fish populations and reduce biodiversity, which are vital for maintaining water quality.
Sustainable water management initiatives
Enforcing water restrictions is one very simple and effective method of improving our water usage. In Sydney alone, water consumption has reduced considerably since the introduction of universal restrictions. Sustainable methods of water management currently being explored include increasing the use of domestic rainwater tanks and utilising stormwater and seawater for human consumption and irrigation. Although seawater is in abundance, desalinising it (removing the salt so that is safe to consume) requires extensive treatment in plants, which can be very costly.
Another sustainable water management initiative is recycling sewage effluent for domestic consumption. In July 2006, a proposal to recycle water in this manner was put to the residents of Toowoomba in Queensland. In the referendum which was held to determine whether or not the new scheme, which has been proven safe, would be implemented, 60 per cent of the electorate voted 'no'. It is, however, becoming increasingly apparent that solutions such as this would be much more sustainable than the systems currently in place in Australia for managing water.
The 'National Water Initiative' is the federal government's framework for water reform on a country-wide scale. It was implemented in 2004 and represents an integrated approach to the issue of water management because it has been signed by all governments of all Australia's States and Territories.
Cooperation between State and Territory jurisdictions is essential in Australia because many of our water sources stretch across borders, meaning that use of water in one area can have very negative consequences in another. The principal aim of the National Water Initiative is to have different jurisdictions working collaboratively to improve Australia's current systems for water use. This will help to ensure that Australia's river water and groundwater sources are healthy and that our use of them is equitable and sustainable.