Sea level rise impacting NT’s unique river systems 


Charles Darwin University researchers are modelling the possible future impacts of sea-level rise on some of the Northern Territory’s iconic river systems.

CDU Water Resources Engineer Mike Miloshis said the rivers of the Top End were at risk from saline intrusion due to sea-level rise, which is believed to be caused by an increase in greenhouse gas emissions. 

“All our coastal wetlands are within elevations that are vulnerable to sea-level rise,” Mr Miloshis said.

“Saline intrusion to freshwater wetlands has already caused the loss of large areas of dense aquatic and semi-aquatic vegetation, including significant forests and woodlands on the Mary River. It is likely that sea level rise will exacerbate problems and cause losses of large carbon stores.”

Mr Miloshis said that the extensive estuaries, freshwater wetlands and floodplains, which were typical of Top End river systems, were home to a variety of wildlife endemic to the NT.

“Saline intrusion has been occurring on a significant scale since the 1960s in a number of locations including Kakadu, The Finniss and the Mary River,” he said. “Expansive areas of the Mary River system that were once fresh water paper bark forest are now hypersaline mudflats harbouring little biodiversity.”

As part of the project, Mr Miloshis is using hydrodynamic models of sections of the Mary River and Arafura Swamp under different sea-level rise scenarios to look at the potential detrimental effects of saline intrusion on Top End systems.

“Our focus is on interactions between channels and determining locations that are most active for future intervention sites to prevent further damage,” he said.

“The Mary River wetlands are the most vulnerable in Australia. Our model shows that by 2100 salt water inundation due to sea-level rise on areas of the Mary River could be up to 25 kilometres inland during spring tides. This is based on a predicted sea level rise of 0.8 metres. Further upstream, Corroboree Billabong will be severely affected by salt water intrusion.

“We are also looking at the value of managing disturbance to natural barriers, through the construction of artificial barriers or repairing, or supplementing natural barriers.”

Mr Miloshis said the project followed on from similar projects that the hydrodynamic research team at CDU is involved with.

“We will apply our experience of river and coastal modelling software and look forward to sharing data and results for future applications in the NT,” he said.