Oct. 17, 2000 (M2 Communications)—The ultimate fate of the Australian landscape can be accurately charted in declining water quality, one of the nation's leading water scientists claimed today.
"It is only now, however, that we are starting to build an integrated, nationwide picture of water quality which means we have lacked a complete picture of what is going on in our major catchments," the Chief of CSIRO Land and Water, Dr Graham Harris says.
"Water links our whole landscape, from hill slope to estuary. By "reading" the changing chemical composition of our water, we can assess how well or badly we are managing a catchment," he says in the 11th Jack Beale Memorial Lecture.
"We now know that every water system has a 'point of no return', when it is overloaded with pollutants of various kinds and collapses. Together with the National Land and Water Resources Audit and Environment Australia, we are now looking to assess how far down that road Australia's main water systems have gone." Dr Harris presents the Jack Beale lecture "The Health of Australian Rivers" at the Australian National University's Manning Clarke Theatre 1 tonight (17.10.00) at 8pm.
By analysing the chemical composition of water - how much sodium, calcium, iron, chloride, sulphate and so on it contains - water scientists can construct an accurate picture of what is happening higher in the catchment, he says.
"That means we get early warning of problems before they become unmanageable." Dr Harris warns of a looming future crisis caused by acidification and sodicity of soil and water systems. Our land use has changed the hydrology and the biogeochemistry of the landscape with the consequence that a new set of chemicals will begin to be released from the land to our waterways. The implications for water quality may well be as great as that of salt.
"At the moment we are encouraging farmers to plant deep-rooted legumes like lucerne to reduce the risk of salinity.
"The trouble is, these plants cause a build-up of acid in the soil. The area of acid soils in Australia is far larger than the area affected by salt, and potentially a much greater threat to agriculture and natural ecosystems.
"By analysing water quality we can see such problems before it is too late, and take steps to head them off," Dr Harris says.
Water quality studies also reveal the level of suspended solids in our murky waters caused by runoff from the catchment. Turbid rivers, which once ran clear, are now losing their large water plants, making room for blooms of toxic algae.
Dr Harris says the balance between nitrogen and phosphorus in rivers relates directly to what is done in the catchment. When the balance tips too far towards phosphorus, it creates ideal conditions for algal blooms.
"Poor river management often makes matters worse by reducing the volume of river flows and increasing the residence-time of water in a section of the river.
These still, turbid, phosphorus-rich waters all encourage algal blooms.
Dr Harris says several of Australia's river or coastal estuaries show signs of degradation, as we have seen recently in Victoria's Gippsland lakes and the Swan-Canning estuary in Western Australia.
"We can expect more of these collapses of our aquatic ecosystems to occur if we continue to develop cities and farms in our coastal catchments," he warns.
"Water quality data can provide us with a very clear signal when something is starting to go wrong in a river or estuary - often in time to take remedial action.
"And while some rivers may be reaching the point of no return, this is by no means true for all. Prompt action, as in the case of Port Phillip Bay, can help protect them for the future." Dr Harris says Australia's water quality data is literally a goldmine of information about the continent and how it is managed.
"We've been seeing with new eyes the very valuable information available in water quality data."
