by Milton Speer and Lance M Leslie
Water flows in mainland Australia’s most important river system, the Murray-Darling Basin, have been declining for the past 50 years. The trend has largely been blamed on water extraction, but our new research shows another factor is also at play.
We investigated why the Darling River, in the northern part of the basin, has experienced devastating periods of low flow, or no flow, since the 1990s. We found it was due to a decrease in rainfall in late autumn, caused by climate change.
The research reveals how climate change is already affecting river flows in the basin, even before water is extracted for farm irrigation and other human uses.
Less rain will fall in the Darling River catchment as climate change worsens. This fact must be central to decisions about how much water can be taken from this vital natural system.
A quick history of the Darling
The Darling River runs from the town of Bourke in northwest New South Wales, south to the Murray River in Victoria. Together, the two rivers form the Murray-Darling river system.
The Indigenous name for the Darling River is the Baaka. For at least 30,000 years the river has been an Indigenous water resource. On the river near Wilcannia, remnants of fish traps and weirs built by Indigenous people can still be found today.
The Darling River was a major transport route from the late 19th to the early 20th century.
In recent decades, the agriculture industry has extracted substantial quantities of water from the Darling’s upstream tributaries, to irrigate crops and replenish farm dams. Water has also been extracted from Menindee Lakes, downstream in the Darling, to benefit the environment and supply the regional city of Broken Hill.
A river in trouble
Natural weather variability means water levels in the Darling River have always been irregular, even before climate change began to be felt.
In recent years, however, water flows have become even more irregular. This has caused myriad environmental problems.
At Menindee Lakes, for example, fish have died en masse—incidents experts say it is ultimately due to a lack of water in the river system.
Periods of heavy rain in recent years have dramatically improved water flows…
READ FULL ARTICLE HERE…(phys.org)
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