Skip to main content
Go to search page

Barmah–Millewa reach sediment investigations

In 2019 the MDBA undertook a detailed survey of the River Murray channel through the Barmah–Millewa river reach. 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 reach 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 reach.

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

Sediment management options, as well as doing nothing to manage the sand, have been preliminary assessed and are reported below.

The preliminary assessment key findings are:

  • Doing nothing to manage the sand negatively impacts community identified cultural, social, environmental and economic values of the river reach.
  • There is no single solution available to effectively manage the sand and therefore will likely be a suite of options to complement one another. This suite may include:
    • targeted bank protection of riverbank through on‐ground works
    • the physical removal of sand in targeted areas
    • moving water around the reach to reduce summer and autumn flow rates.

These options will be further developed and assessed in the next stage of the investigation.

Downloads

Barmah–Millewa sediment transport investigation
Barmah–Millewa sediment sources
Barmah–Millewa sediment management options: preliminary investigations