Floodwater tests Avon River pile fields

In 2012, heavy rain caused widespread flooding across Gippsland. Waterways were damaged, productive farmland washed away and vegetation was ripped from its banks.

After these floods, the West Gippsland Catchment Management Authority (WGCMA), worked with private landholders to repair waterways and used innovative techniques to reduce the impact and damage from future floods.

WGCMA’s Project Delivery Team Leader, Matt Bowler, said the recent flooding on the Avon River was the first real test of the pile fields that were constructed in 2014.

“The flooding in July just reached the major flood level in Stratford at 6.5 metres,” explained Matt.

“The pile fields are designed to slow water flows across the large gravel bars on the lower Avon River, catch debris and enable finer sediments to drop out.

“This will help planted and natural vegetation to establish such as River Bottlebrush, Paperbarks and Tea tree.

“Flood resistant vegetation along the river banks and bars is the long term solution that helps stop erosion and other damage caused during major floods,” said Matt.

To create the pile fields, six metre hardwood poles were driven four metres deep into the mobile gravel bars.

These gravels and cobbles have accumulated in the lower parts of the river as a result of the massive erosion processes which followed settlement and the associated vegetation removal and catchment changes.

This created a much more incised and wider river channel through the middle reaches of the river.

Matt said recent inspections of the pile fields on the Avon River had shown they were doing the job they were designed to do.

“We’re really pleased with how they have held up during the recent flood,” continued Matt.

“Over coming years we expect more vegetation to establish in and around the pile fields and in time, as the timber piles break down, this vegetation will take over.”

While the damage where the flooding occurs in the river is obvious, Matt explains the downstream impacts are just as important to prevent.

“The Avon River flows into the Gippsland Lakes and when it floods eroded material and finer sediment is carried downstream and deposits on seagrass beds, impacting fish and other marine life.”

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