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Barmah–Millewa Forest sediment investigations

In 2019 the MDBA undertook a detailed survey of the River Murray channel through the Barmah–Millewa Forest. This revealed the presence of a very large quantity of sand on the bed of the river, something that was not expected. These reports investigate the source of the sand and the rate that it is moving at.

The investigation of the sand in the bed of the River Murray channel through the Barmah–Millewa Forest revealed that the quantity of sand was very large, with an average depth of 1.2 metres between Yarrawonga Weir and Barmah township with some parts of the river having sand depths in excess of 4 metres. This generated 2 key questions:

  • where did such a large quantity of sand originate from?
  • how fast is it moving and will it 'wash through' the system?

The MDBA sought expert technical input to answer these questions which are reported here. The 2 studies have determined the following key findings:

  • the sand, estimated to be more than 20 million m3, is likely due to a combination of land clearing, gold mining, desnagging and river regulation. This means that the sand slug is not a natural feature.
  • the rate of sand movement is higher as the river enters the forest than when it leaves the forest. This means the sand is accumulating in the River Murray channel within the Barmah–Millewa Forest.

These reports are extremely valuable inputs to understanding the sand that is gradually filling the River Murray channel through the Barmah–Millewa Forest and will guide the MDBA in considering a range of options to address this issue.

Downloads

Barmah–Millewa Forest sediment transport investigation
Barmah–Millewa Forest sediment sources