Geographical process

Introduction

The problem of depleted supplies of quality drinking water has become a serious concern in many parts of the globe. In many less-developed countries of the world, thousands of people die each day because they do not have enough clean water to meet their essential survival needs. Australia's relative wealth and level of social and economic development has meant that most of our population has fairly reliable access to clean drinking water. While this serious problem is, therefore, not one that many Australians consider to be of pressing concern in their day-to-day lives, it is important that Australia does not take for granted its relative fortune when it comes to our most precious natural resource.

Since Europeans arrived on the continent, natural water sources have been disrupted by damming and diverting rivers and groundwater in order to cater for expanding settlement and development needs. The way the land has been managed has also had devastating effects on water supplies. The unrelenting spread of salinity across Australia has meant that the availability (or lack thereof) of clean, fresh water in many parts of the country is now an urgent problem. In an urban context, this has been particularly notable in Adelaide over the past two decades, where water salinity levels have caused major water management problems. The crisis of this city's drinking-water supply will form the topic of this case study.

South Australia's population and water supply

South Australia (SA) is the driest State of Australia and Australia is the world's driest inhabited continent. The vast majority of SA's population lives in the Gulflands region of the State and Adelaide's residents alone comprise about 75 per cent of this. See image 1

The future of this source as Adelaide's primary water supply has become cause for concern in recent years. It also raises questions about the way in which this vital natural resource is managed, not only in SA but also in the other four States that depend upon it and share the responsibility for its management.

The stressed Murray-Darling River system

The Murray-Darling River system is one of Australia's most important multiple-use resources; approximately three million Australians in South Australia, Victoria, the Australian Capital Territory, New South Wales and Queensland are dependant on it for their water needs. At 3750km long, it is the fourth-largest river system in the world. Its basin, which covers 14 per cent of the Australian mainland, is often referred to as the 'food bowl' of Australia because it produces such a large proportion of the nation's agricultural products. See image 2

Contrary to what its length may suggest, the Murray-Darling holds a relatively small amount of water. This is largely due to low rainfalls and high levels of evaporation in the areas from which its water is drained. Added to this problem is that use of the Murray-Darling exceeds its natural replenishment levels. Diversion of water upstream for domestic, agricultural and industrial purposes has meant that not much fresh water is available for populations settled at the Murray River's end.

In addition to the declining availability of water, salinity (salt content) levels are a major concern for users of water within the Murray-Darling Basin (MDB). While this is a problem in many parts of the river system upstream, it is of greatest concern in areas surrounding the mouth of the Murray River in SA. Indeed, an alarming statistic is that salinity levels of Adelaide's main source of drinking water exceed World Health Organisation (WHO) standards for around 10 per cent of the year. Even more disquieting are predictions that within two decades Adelaide's major drinking water supply will not pass WHO standards 40 per cent of the time. The lack of fresh water at the Murray River's mouth has also negatively affected the ecological integrity of the Coorong Wetlands and surrounding areas. This has seen a reduction in biodiversity, particularly amongst pelican populations. Some migratory bird species fly to the Coorong Wetlands from as far away as Siberia and Alaska to use this unique habitat as a breeding ground.

What is water salinity?

The level of salt in a waterway can be seen as relative to the amount of land within its catchment zone that is affected by salinity. There are two categories of salinity that affect the Australian landscape: primary salinity and secondary salinity. The former is a result of natural processes such as low rainfall and high evaporation. The latter is a result of humans using the land in ways that alter the natural salt balances of the soil and water. There are two categories of secondary salinity: dryland salinity (caused by mass vegetation clearing) and irrigation salinity (caused by excessive watering of crops and pastures).

Excessive use of the land for farming and irrigated agriculture over the past two centuries is a major cause of secondary salinity in Australia. Since Europeans arrived over two centuries ago, massive areas of vegetation have been cleared in order to create pastures, grow crops and harvest timber. The removal of this vegetation has meant that, when it rains, there are fewer trees to absorb the water. An unnatural amount of rainwater is therefore able to seep into the ground, which causes water tables to rise. As the water tables rise, they bring with them the salts that are naturally found in the deeper layers of the earth. During periods of heavy rain, the salt that has accumulated at the surface ends up flowing back into the rivers with the stormwater runoff.

Excessive use of the river water to irrigate crops and pastures has similar effects on river water. When water is pumped out of rivers to water these crops and pastures, it absorbs the excess salts in the top soil (which have accumulated due to rising water tables) and then drains back into the river. In 2003 it was estimated that there were around 2.3 million areas of salt-affected land in Australia. The State most affected by this is Western Australia, however, South Australia is not far behind. See animation 1

Measuring salinity

Water salinity is measured using either the parts per million (ppm) or milligrams per litre (mg/l) indices. In Australia the average level of salt in drinking water is 50 mg/l; sea water is about 35 000 mg/l. People can start to taste salt in water at about 180 mg/l. To gain an idea of how water use affects the salinity of water within a river system, variations in salt levels at different stages of the Murray-Darling provide a good example. At the start of the river in Qld the level of salinity is 25 mg/l; at the river's mouth, in Morgan SA, the salinity level can sometimes rise to 480 mg/l. This is the point in the Murray River where water is extracted and pumped to major urban centres in SA, including Adelaide, Port Augusta, Whyalla and Woomera. The amount of salt that flows downstream from Morgan is double the amount which enters SA at the Victorian border, only 100 km to the north. See image 3

Levels of salt in water can be ascertained using a process called electric conductivity (EC). As salt water is a much better conductor of electricity than fresh water, testing the voltage at which an electric current passes through a body of water can reveal how much salt is present. The salt content of water can also be measured by testing for levels of sodium, calcium, chloride and sulphate in a scientific laboratory.

Water management initiatives in the MDB

As there are many factors contributing to water salinity, and because a multitude of problems are caused as a result of it, a number of initiatives have been implemented within the MDB over time. In Australia, management of water resources is controlled by the State and Territory governments, who grant permits to groups and individuals who wish to use water within their jurisdiction. To keep levels of water extraction from rivers constant, rather than allow for increases in entitlements, farmers and irrigators (more so than exclusively domestic users) are permitted to trade the water which they have been allocated with other users.

This system becomes complicated, however, when massive water resources extend across numerous State borders. It simply would not work if each State distributed water amongst their users as they pleased, without consideration of people who rely on the water downstream. The quantity and quality of Adelaide's drinking water supply for example, depends on what is happening throughout the entire MDB, beginning thousands of kilometres north in Qld. Initiatives to improve water in Adelaide, therefore, cannot be isolated to SA. The onus of responsibility falls on each and every State that uses it.

To facilitate a much-needed integrated approach to water management in the MDB, the Murray-Darling Basin Initiative was set up in 1992. Three bodies make up the initiative:

• the Murray-Darling Basin Ministerial Council. This is the policy and decision-making body, made up of Ministers from each of the States within the MDB.
  
• the Murray-Darling Basin Commission. This is an autonomous organisation that liaises with and represents each of the State governments. It is responsible for implementing the Ministerial Council's policies for how water should be allocated within the MDB.
  
• the Community Advisory Committee. This body provides advice to the Ministerial Council from the community perspective. It comprises of a board made up of community members with a high level of experience in water-management issues.

The Murray-Darling Basin Initiative is one of the world's largest integrated river-basin management programs. It spans across the five jurisdictions of Qld, NSW, the ACT, Vic and SA. Since its inception, the Initiative has developed many strategies to improve water management within the MDB.

In 1995 a system was introduced which placed a limit on water diversions and consumption levels across the entire MDB. The system is known as ‘the Cap' and will form the basis of this Topic's case study. As the Murray-Darling Basin Commission (MDBC) is the body responsible for implementing it, much reference will be made to this organisation throughout the various chapters. Even though the Cap was not developed with the specific focus of addressing the drinking water crisis in Adelaide, it was a strategy with broad and multiple aims that would lead to a number of positive outcomes in the MDB.

The Cap is used as an example of one strategy that has the potential to improve Adelaide's drinking water. This Topic will explore the perceptions of various interests groups towards water salinity in the MDB and their opinions on what should be done about improving Adelaide's water supply (Chapter Two); the Cap system that was introduced and how it is managed (Chapter Three); the various States' responses to the implementation of Caps (Chapter Four); and the implications that this strategy has for sustainability, social justice and equity (Chapter Five).