The Murray River in Australia

From EnvironmentWiki

1 Water levels in the Murray River
2 River Red Gums
3 WHAT’S UP WITH THE MURRAY RIVER ? Some Facts
4 Historical Records of the Murray River
5 Murray River Flows and Gauge Height Data

Water levels in the Murray River

By Jennifer Marohasy

Water levels in the Murray River are controlled by the Murray Darling Basin Commission through releases from Hume and Dartmouth Dams. Before these dams were built the River ran dry during periods of drought.

For more information, click here Water levels in the Murray River

River Red Gums

for more information on River Red Gums, click here River Red Gums

WHAT’S UP WITH THE MURRAY RIVER ? Some Facts

--Nichole Hoskin 13:53, 24 July 2008 (EST)

The Murray River is Australia’s longest river and together with its tributary, the Darling River, drains an area known as the Murray Darling Basin. The region has historically received only 6 percent of Australia’s annual rainfall but produced 40 percent of Australia’s food.

For years it was feared the region would be lost to salt from rising water tables, now it is feared the river will run dry from a long term decline in rainfall associated with climate change. So far there has been no long term decline in rainfall, but there has been a dramatic decline in the amount of water flowing into the Murray River.

Farm dams are estimated to have reduced inflows by between 660 and 2,400 gigalitres per year

Groundwater pumping is thought to reduce inflows by 327 gigalitres.

In early 2003 over a million hectares of native forest was burnt, much of this in the Murray Darling Basin. Regrowth from the fires could reduce inflows by 430 gigalitres by 2020.

New plantations could further reduce inflows by 1,100-1,400 gigalitres per year.

Doom and Gloom Predicted

CSIRO is modelling future water availability for 18 sub-catchments within the Murray-Darling Basin. The first report for the Warrego region in southern Queensland claims that given climate change there could be a 28 percent increase in river flows or a 44 percent decrease. In the Wimmera, there could be anywhere between a 1 and 47 percent reduction in mean annual runoff and for the Goulburn-Broken there could be anywhere from a 2 to a 44 percent reduction in runoff by 2030.

The CSIRO reports states that there is no warranty in relation to the data including for accuracy, reliability, completeness, currency or suitability.

No Reduction in Rainfall in the Murray Darling Basin

In October 2006, an influential report by British economist Sir Nicholas Stern on climate change stated that the east coast of Australia – home to over 70% of the population and location for most major cities – had already suffered longer droughts and declining rainfall as a consequence of climate change.

But in fact, data from the Australian Bureau of Meteorology, for the period 1900 to 2006, shows there has been no long term decline in rainfall in eastern Australia or the Murray Darling Basin. Sir Nicholas was wrong.

River Levels Not at Historic Lows

In August 2006, it was reported that water levels in the River Murray were at historic lows.

“The water level in the Murray River is at its lowest since records began more than 100 years ago.” ABC News Online, Murray River flows at record low, August 17, 2006

In fact, despite the drought and low inflows, the Murray River was running strongly with 4.1 gigalitres of water passing Riversdale each day. Local farmers, Daryl McDonald, remarked that this was, "Quite amazing considering we have had the lowest inflows on record. It should be noted that South Australia still expects its guaranteed 1,850 gigalires per annum, while NSW irrigators have a zero allocation, and the Victorians are on 50 percent of their average 160 percent Water Right."

Before the Hume and Dartmouth dams were built, the River did run dry during periods of drought.

"Water was never more than two feet six deep while we carted [timber], and for a long time in Autumn 1915 was perfectly dry, the river having stopped running in February or March". '100 Years at Rosevale' by Russell McDonald in 'Picnic in the Murray in Defiance of the Drought' by Marianne Cockroft

Water Flowing to South Australia

The height of the River in the central Murray Valley has been measured since 1974 and over this period has fluctuated from 0.5m to 4.6m with peaks in spring and troughs in autumn.

Even during the recent drought an average of 5.5 gigalitres of water has passed Swan Hill each day (2000 – May 2008), on its way to South Australia. South Australia has received 76% of its annual entitlement flow in recent years, as a reduced entitlement.

Salt Levels Not Rising in the Murray River

For years, there have been fears about salt levels in the Murray River. In fact, through the construction of salt interception schemes and changed land management practices, salinity levels have been falling since 1982, including at Morgan.

Morgan is just upstream of the pipeline off-takes for Adelaide’s water supply. Its use as an indicator site emphasizes the relative importance of river salinity impacts on all water users in the system.

The Murray River has not been lost to salt and, since the construction of the Hume and Dartmouth dams it has not yet run dry.