Picture: supplied
One of Australia’s longest rivers, the Murrumbidgee is drying up due largely to irrigation and dam-building, according to new research from UNSW Sydney.
A study from the university’s Centre for Ecosystem Science has revealed the extent of falling flows in the river.
A UNSW statement says that over 30 years, the river lost 55% of its water at Hay, in the Riverina, due to dams and upstream water diversions for irrigation.
It pinpoints the most severe impact is being in the river’s largest wetland, the Lowbidgee Floodplain (3250 square kilometres).
“Flooding isn’t something to fear in these wetlands – it’s essential for life to thrive,” says Jan Kreibich, a PhD candidate at UNSW who led the study.
“The Lowbidgee Floodplain depends on regular inundation. Without it, entire ecosystems are collapsing.”
A research team from the centre teamed up with the Nari Nari Tribal Council and CSIRO to study changes in river flows in the lower Murrumbidgee River since 1890. Their findings were published in the international Journal of Environmental Management.
The findings are a wake-up call, says Jamie Woods, one of the study authors who is also a Nari Nari man and general manager of Gayini wetlands.
“This is a wake-up call about how much damage has been done to our country and cultural and environmental values from upstream development, with climate change further reducing flows.”
The study says that in the last 100 years, 26 major dams and reservoirs were built along the 1700 km Murrumbidgee River, diverting much of the natural flow for irrigation.
With climate change posing a serious threat, the study says that river regulation has had an even greater impact, the UNSW says.
Human interventions caused flood return periods to more than double and disrupted the natural cycle that keeps these wetlands healthy, it said.
“Climate change could reduce river flows by another 7-10% by 2075, adding to the impacts of water management which were 5-8 times greater,” explains author Professor Richard Kingsford, Director of UNSW’s Centre for Ecosystem Science.
“The main driver of change right now is river regulation. That’s something we can change if we choose to.”
“This research highlights how the ecosystem is suffering a death by a thousand cuts. Each upstream diversion is another cut on the downstream wetlands,” says study author Professor William Glamore from UNSW’s Water Research Laboratory.
CALL TO ACTION
“There’s hope for the Murrumbidgee River system but we need to act now,” says Kreibich.
“If we increase water-use efficiency, especially in irrigation, and the delivery of targeted environmental flows, we can help restore these ecologically and culturally significant floodplain wetlands.”
The researchers want better management of Australia’s freshwater ecosystems to protect biodiversity, reduce the impact of climate change, and honour the cultural heritage of First Nations Peoples.
“This is about more than just the environment – it’s about our shared future,” Mr Kreibich says.
