And then the waters covered everything and the forest was gone.

Flooding the Murray River


In June 2018, Dr Brad Duncan wrote on his Facebook page

Amazing place at Lake Mulwala – they have drained the lake and all the old drowned forests and wrecks are exposed.

Photos of a seemingly desolate, post-apocalyptic landscape accompanied his words. We were immediately intrigued and in July 2018 we undertook a collaborative pilot study of the lake, days before it started to refill.

The lake was artificially created when the Yarrawonga weir was installed to create water reserves as part of the Murray Basin irrigation scheme. This drowned landscape is repeated through the basin. The ‘lakes’ are periodically drained in order to control a weed that grows prolifically in the water system by simply drying out the area over a number of weeks per site.

ABOUT

The many thousands of kilometres of navigable rivers connecting the vast coast of Australia to its interior have played multiple roles, from colonising corridors to conduits for ongoing travel and trade, irrigation water for communities and farmers, and power supplies for industry. The rivers were the lifeblood of the colonies and later the new nation, connecting the separate parts and becoming the focus for cultures built around the understanding and uses of these flows. Different rivers and river systems in different areas presented a range of challenges and saw innovative responses of technologies and practices, some adapted from elsewhere and others originated in place.  Despite being the highways to the interior, the cultural heritage of the nations rivers have until recently been under-explored with a focus on the more glamorous maritime stories of the coast.

Beginning in 2010, a joint research venture between Dr Brad Duncan (NSW Heritage Branch, now Heritage Division) and Prof Martin Gibbs (University of Sydney, now University of New England) established the NSW Rivers Project to investigate the riverine heritage of NSW. Working with multiple collaborative partners across the state and country, the project aims to investigate the rich history and diversity of cultural interactions in and around waterways that cross state boundaries. The project has so far documented well in excess of 600 new sites and their archaeological and anthropogenic signatures that characterise riverine life around the states waterways in 28 rivers, lakes or inlets. A plethora of sites types are being explored; including shipwrecks and abandoned vessels, riverine infrastructure such as wharves, slipways and loading facilities, and the inadvertent and deliberate environmental modifications associated with various trades and industries. The project aims to work closely with local communities to promote and recognise their riverine heritage sites, cultural landscapes and customs, all of which are informed by rich local oral histories and traditions. The project operates on many levels, seeking to improve the knowledge of waterway heritage sites around the State, whilst also driving higher level academic research into behavioural cultural conformity and diversity, along with temporal, spatial and environmental/ anthropogenic change within and between different NSW river systems. This will help us better understand the ways that communities lived and used waterways around the country.

HOW & WHY?

The project was hastily developed in order to take advantage of the drained lake before it was due to be re-flooded. The aims and objectives of this pilot studywere to:

  • locate and document cultural features including wreck sites
  • identify potential sites along the palaeo-channels of the river

The objectives set to meet these broader aims were developed live as we got a better feel for the landscape conditions and the nature of the material – they were to:

  • record any wreck sites immediately noticeable and accessible
  • undertake sidescan survey of known submerged sites
  • undertake aerial survey of the lake for other wreck sites and cultural features
  • aerial survey to record palaeo-channels of the river

Aerial surveys were to be undertaken by drone. We also had the very generous offer by pilot, Kaz Gurney, to fly her plane over the area and rapidly record the entire lake!

LESSONS & FUTURE

We quickly realised that we were in fact undertaking a rapid survey of a large area and were coming up with the best way to do it on the spot given our time and resource constraints. This gave us some interesting data and raised some intriguing and worthy research questions and topics for post fieldwork processing and for future work:

  • Comparison of aerial vs ground footage for Agisoft Photoscan 3D photogrammetry (and combined)
  • Comparison against LIDAR from previous surveys
  • Comparison of sides scan sonar to above – test accuracy/ interpretation of readings
  • Effects of Anthropogenic Environmental change
  • Paleo-environmental channels – core sampling to determine previous environmental conditions

ALL non watermarked imagery: © Brad Duncan