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News > Water in Australia – Rivers and Estuaries FAQ 26th, August, 2010

Category: Misc

Frequently Asked Questions

  • Why are rivers and estuaries important?
  • What threats exist to our river systems?
  • What causes water degradation?
  • What causes algal blooms?
  • How can river and estuary health be improved?
  • What can I do to protect my local river or estuary?
  • Where can I get more information on related issues?

Why are rivers and estuaries important?

Water is one of the most important resources that exist on the planet. It is central to the existence of life and links all of the natural processes that occur on Earth.

Water affects all of our land uses and every aspect of our environment. By the same token, whenever we change our land uses we change the way in which water interacts with the landscape, and this has an ongoing effect on the biology and chemistry of the land.

International problems of over-population, resource depletion, over extraction of water and the destruction of biodiversity, have put immense pressure on the management of water resources. Many people in the world suffer from a lack of access to reliable clean water. The United Nations has produced reports showing that water is, and will increasingly be, a source of national and international conflict.

In short – water is not a resource that we can afford to take for granted.

Australia’s river systems and estuaries are central to agriculture, biodiversity, urban and rural water supply, human health, culture and community, coastal resources and tourism.

What threats exist to our river systems?

The Australian landscape has seen an enormous amount of change in the last two centuries, including significant clearing of native vegetation, the building of infrastructure, agriculture and irrigation, and the diversion of water for power and supply.

Whenever we change the landscape we run the risk of introducing undesirable side effects. Our river systems and estuaries bear many of the consequences of this change.

Significant problems that now occur in many Australian rivers and estuaries include gullying and erosion, nutrient imbalances, contamination, salinity, algal blooms and loss of biodiversity.

What causes water degradation?

A healthy river or estuary is comprised of a number of different factors, including water flow, biodiversity, sedimentation, turbidity and water quality. When the system is in good condition, all of these factors are in balance and the rest of the catchment or marine environment are also in better condition.

When any of these factors are thrown out of balance through inappropriate land use, the entire system is affected. To use just one example, farming practices that cause erosion on the land can also cause large amounts of earth to be spilt into the catchment’s river system. This excess sediment affects how well the water flows and can increase the muddiness of the water (turbidity). When the water is muddier and doesn’t flow as fast, the amount of light that filters through the water can change and so can the nutrient balance. In turn, this may mean that native plants and animals can’t thrive – but some introduced or toxic species can.

In this scenario, a single land-use choice affects the health of the entire catchment. For this reason, CSIRO Land and Water looks at all aspects of land use and development that can affect the health of a river and or estuary.

What causes algal blooms?

In Australia, toxic blue-green algae appears in rivers, estuaries and water storage systems both in the tropical north and in the more temperate southern parts of the continent.

Algae requires nutrients in order to grow – especially nitrogen and phosphorus – as well as a relatively low water flow.  Light and temperature also help determine the ability of algae to flourish.

When excess nutrients enter a water body from sources such as sewage effluent, fertilisers, eroded soils, stormwater runoff, groundwater and industrial waste, the result is a feast for toxic algal growth.

If the water flow is relatively low, there is less opportunity for the waters in the river or estuary to mix and for the algae to be flushed away. A river system, water storage or estuary with low flow and high turbidity, and polluted with a lot of phosphorus and nitrogen-rich material is more likely to disappear under a layer of toxic blue-green algae every now and then. On the other hand, a healthy water course that is clean and flows strongly, is much less likely to develop algae problems.

CSIRO Land and Water researchers have been investigating the causes of algal blooms, and looking for ways to prevent the blooms from appearing in our water courses.  Read some more information about algal blooms.

How can river and estuary health be improved?

Because water is such an important resource – and because it will become even more important in future – improving the health of Australian rivers and estuaries is a problem that should be dealt with by government and industry, and also by every individual Australian.

Water health can be maintained if our environment and communities are managed in a way that is sustainable.  We need to balance the drive for profit with the need to improve the efficiency of our water use and preserve the environment.

CSIRO Land and Water scientists work in conjunction with federal, state and local government agencies, industry groups, other researchers, water and land managers and community groups, to look for ways in which we can deal with the damage that has already occurred in our waterways, and also to find practical economically viable ways in which we can manage our water resources.

Our challenge is to take what we know about rivers and estuaries and turn it into useful information that can be put into practice by governments and society.  We need to research more about impacts of altered flow regimes and salinity on aquatic ecosystems, ecosystem structure and function and about the links between agriculture, land use and water quality.

What can I do to protect my local river or estuary?

Every Australian has the opportunity to do something towards improving the health of our rivers and estuaries – starting with how much water we use in the home, at work, and at school.

The are a lot of different ways in which we can use less water, and improve the efficiency of the water that we use.  For some handy tips on saving water for the health of our rivers and estuaries, check out the following websites:

Where can I get more information on related issues?

http://www.clw.csiro.au/issues/water/rivers_estuaries/faq.html#Health

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