Report from the inquiry into the 2022 Victorian Floods

by Adeel Siddiqi and Ben Kimber
Legislative Council, Parliament of Victoria

Improving resilience to climate change and climate-fuelled weather events is the broad aim of a state parliamentary inquiry’s final report into the 2022 flood event in Victoria.

The Legislative Council Environment and Planning Committee’s report makes 73 recommendations to the Victorian Government, including for the Government to collaborate more with scientists to understand how modelling can be used to better predict climate change impacts on flooding.

In their respective evidence to the Committee, the Bureau of Meteorology and ARC Centre of Excellence for Climate Extremes noted the link between climate change and an increase in short-duration, high-intensity rainfall in Victoria.

The latter cautioned the Committee about relying on products offered to the government that purport to project extreme rainfall at a very localised scale, asserting that detailed forecasts of this kind are beyond the current state of climate science.

Models informing planning

Modelling is being used by water authorities in both Melbourne and regional Victoria to inform planning regimes. The Committee heard from Melbourne Water about its plans to remodel all of Melbourne’s water catchments to incorporate climate change projections to the year 2100, and its intention to use this information to assist with planning processes in potential flood-prone areas.

The updated modelling will be used to produce maps of floods with a 1% chance of occurring or being exceeded, including in 2100.

Working with planning authorities, Melbourne Water will incorporate the 2100 maps into planning schemes, ensuring planning decisions throughout metropolitan Melbourne reflect increased flood risk as a result of climate change.

In response to the 2022 floods in Maribyrnong, Melbourne Water released fast-tracked modelling of the Maribyrnong River catchment.

Flooding along Melbourne’s Maribyrnong River

The models project a marked increase in nominal flood depth between 2024 and 2100 in areas adjacent to the Maribyrnong River, including the Kensington Banks development.

In a 2024 1% flood scenario, the model projects Kensington Banks would experience 0.84 m nominal flood depth, whereas in a 2100 flood scenario, this flood depth is projected to almost double at 1.57 m.

Appearing before the Committee, Managing Director of WMAwater and member of the independent Maribyrnong River Flood Review panel Mark Babister highlighted the significance of climate change’s impact on flooding in Victoria.

“The chance of the 2022 flood occurring, say, back in the 60s, 70s, 80s or 90s was about 2% each year,” he said.

“Because of the warming already today it is about 50% more likely. By 2030 it will be about 60% more likely.

“Depending on what CO2 emission scenarios we end up on, it could end up at 2060, at two times more likely and in 2090 it could end up as bad as three times.”

Planning for the changing climate

The Committee concluded that regardless of local-scale climate modelling, climate change is having a profound effect on extreme weather events, including floods.

The inquiry’s final report urges the Victorian Government to plan for and mitigate the impacts of climate change on the built and natural environment, and for planning authorities to address climate change at all levels of the planning process.

Implementing climate projections into local planning schemes is one way of doing this.

The October 2022 flood event devastated large parts of the state, particularly the northern Victorian areas of Rochester, Echuca, Seymour and Shepparton, and inner-city suburbs surrounding the Maribyrnong River.

After 18 months of research and public hearings, involving dozens of individuals and organisations, the State Government is considering all of the findings and recommendations contained in the 477-page report.

The parliamentary committee, which consists of government, opposition and minor party MPs, is now conducting an inquiry into climate resilience, investigating the main risks facing Victoria’s built environment and infrastructure from climate change and the impact these will have on the people of Victoria.

• Read the floods report and watch a summary of the key findings and recommendations: vicparl.news/floodreport
• Watch coverage of the floods inquiry, including public hearing highlights at vicparl.news/floodinquiryvids

Adeel Siddiqi is a Research Assistant and Ben Kimber is a Communications Adviser, both working for the Legislative Council of the Parliament of Victoria