Merri Yarra confluence mixing smallThe first activity of MCMC's Upper Merri Sodic & Erosive Soils Working Group kicked off with a special presentation by eminent soil scientist Dr Robert van de Graaff in October 2019.  Dr van de Graaff explained that due to the geological and climate history of the Merri Creek catchment, most soils in the catchment are sodic and thus highly susceptible to erosion. These soils present major challenges for urban development and until now have been largely overlooked.  Detailed mapping of the soils and assessment of the degree of risk they pose is sorely needed. Dr van de Graaff's presentation is here (8.8MB pdf). 

Photo: The muddy Merri (foreground), thick with sediment from sodic soils in the upper catchment, meets the Yarra, June 2018 © Katrina Roberg

A facilitated discussion followed the presentation, with active participation by attendees from Melbourne Water, Yarra Valley Water, EPA, Victorian Planning Authority, Whittlesea, Hume and Mitchell Councils, the Friends of Merri Creek, Wallan Environment Group and the Yarra Riverkeeper.  Two thirds of the respondents identified more knowledge of the soils as the one thing that most needs attention between now and February 2020. This was a very strong endorsement of the need for a soils investigation for the upper Merri. A strong case was also made about the need to manage erosion already been set in train from the exposure of sodic subsoils in development areas. 

The event was extremely well received with 21 out of 22 respondents saying the session was 'very worthwhile' - the highest possible rating. MCMC was thanked by numerous of participants for taking the initiative in organising the event. We are considering a follow up event in February/March 2020 for stakeholders to report on progress in tackling the soils knowledge gap and related management issues. 

Especial thanks are due to Dr Robert van de Graaff, who provided his expertise on a pro-bono basis, assisted by Scott Seymour from Aquatic Ecosystems Management, who also contributed his time pro-bono pro-bono. Thanks also to the City of Whittlesea for provision of the meeting room, welcome refreshments and general support, and to Darcy Coombes, the Working Group Support Officer (pro-bono).

The Upper Merri Sodic & Erosive Soils Working Group is an initiative of Merri Creek Management Committee (MCMC) in response to the severe turbidity in Merri Creek experienced in the middle of 2018.