Erosion of bank difficult to recover

By Country News

Permanent damage to the banks of the Goulburn River is likely following the planned inter-valley transfers, according to fluvial geomorphologist Geoff Vietz.

Dr Vietz, the director and principal scientist of waterways consultancy firm Streamology, said the Goulburn was already showing the effects of large inter-valley flows during recent summers.

“Once erosion of the bank occurs in the way it's been happening, it is very difficult to go back to the original bank shape,” Dr Vietz said.

He said the erosion of the lower banks, including notching, occurred when they were inundated for prolonged periods. This destabilises the mid and upper banks which no longer have the support of the bank toe.

This makes them vulnerable to collapse in larger flow events.

“These prolonged, regulated flows are really preparing the riverbanks for later collapse, making them less resilient,” Dr Vietz said.

He said the impacts had been very evident for quite a number of years.

Streamology has been assisting the Goulburn Broken Catchment Management Authority with the long-term monitoring project, which is assessing the impact of environmental flows along the lower Goulburn River.