News / Environment
Flood risk for hundreds of homes in Brunswick and Coburg
Climate change increases threat of flash flooding in parts of Merri-bek
Flash flooding in Sydney Road in September 2014. Photo: Facebook
Mark Phillips
ALMOST 1300 properties in Brunswick and Coburg have been deemed at risk of severe flooding from a heavy storm in new modelling by Melbourne Water.
Parts of the two suburbs could be declared off limits for future development as flash flooding is expected to become more frequent and more intense because of the impact of climate change on weather patterns.
The warning follows the most detailed modelling ever undertaken by Melbourne Water of its main drainage systems and waterways in Merri-bek to identify properties that could be in the path of stormwaters in a one-in-100 years flooding scenario like that which devastated parts of Kensington and Maribyrnong in the spring of 2022.
The maps are intended to act as a guide for future planning and development and also help property owners assess their own flood risk, including the level of insurance they need.
Separately, Merri-bek Council is currently seeking approval for amendments to its planning scheme with a new special building overlay after reviewing and updating its own maps of the council-owned drainage system.
Melbourne Water is responsible for all 1400 km of regional and main drains as well as creeks and other waterways across the metropolitan area. Local drains are managed by councils.
The new modelling is the first comprehensive review conducted by the water authority for a decade as it updates flood maps for the 38 municipalities in its catchment. Merri-bek is one of the first municipalities to be reviewed.
Melbourne Water has produced two maps for Merri-bek – one which models flooding today and another for the year 2100.
While the overall picture does not show a significant change in flood extent compared with existing maps, the mapping introduces a new site-specific rating system with 1280 properties in Brunswick and Coburg deemed as high hazard where floods of at least two metres deep that would be unsafe for people and cars.
Another 4418 properties have been assessed at lower hazard ratings where water depths in a severe storm would not exceed 1.2 metres – which would be below the floor level of many homes – and are already subject to existing flood overlays.
But as the population grows and global warming increases by the end of this century flood risk is only going to get worse, according to Melbourne Water’s Executive General Manager, Service Futures, Chris Brace.
“With climate change and urban growth, floods are projected to become more frequent and severe,” he told a recent webinar on the new Merri-bek mapping.
One-in-100 year flooding scenario for Brunswick
Click on the map to see it full size
Brace said most of Merri-bek’s urban drainage was at least 60 years old with some sections first laid a century ago.
While they can cope with most common and regular low intensity storms, in extreme events – which are becoming more frequent because of climate change – there is a risk that more water will be generated than the drains can cope with.
Brace said climate change was built into the latest modelling and it would cause more severe storms and have a bigger impact on flood management in Merri-bek towards the end of the century.
“It’s really important that we raise awareness about flood risks in the community which enables us to support safe planning, safe building decisions, and guide long time investment into reducing flood risk over time,” he said.
Brunswick, Brunswick East, Coburg and Pascoe Vale are the most regularly flood affected parts of Merri-bek.
Areas most at risk include a cluster of houses in Brunswick West, nestled alongside the City Link tollway and just south of Moreland Road; an area in Brunswick East near Sumner Park; and an area of Shaftesbury Street in Coburg between Reynard and Munro streets.
Much of the area deemed as medium or higher hazard follows the path of what was once known as the Melville Creek, a former tributory of the Moonee Ponds Creek which winds from Pascoe Vale to Brunswick West. The creek was converted into an underground drain in the first half of last century.
Sections of central Brunswick between Albert and Albion streets are mapped as subject to low hazard flooding below 50 centimetres.
Further north, heavy flooding has been modelled for an area of Coburg North west of the Upfield line between Batman Station and the Fawkner cemetery.
A one-in-100 storm event is an engineering, planning and environmental standard for measuring stormwater probability and producing flood maps. It portrays the impact from a storm that is expected to occur once a century.
In the future, Melbourne Water expects to review its maps every five years and update them once a decade. Next year, it will publish new maps showing one-in-100 years flood modelling for the lower Merri Creek and Moonee Ponds Creek.
Separately, Merri-bek Council has updated stormwater mapping for its own smaller local drainage system and is currently seeking approval for planning scheme amendments to create new building overlays for flood prone areas.
It has identified 6503 properties that are at risk of significant stormwater damage and will be subject to the new rules.
In a submission to the Melbourne Water mapping review, the council is seeking more information about the authority’s long-term investment priorities for main drainage upgrades to manage flood risk in Merri-bek.
“Climate is changing, we’re going to have more floods and it’s very important we stay on top of what is happening,” said Box Forest ward councillor Chris Miles, who shares responsibility for the urban planning portfolio area.
Melbourne Water will begin flood mitigitation works in Glenroy in mid-2026.
Public consultation on the new Melbourne Water maps will close on December 5. The authority is particularly interested in real life experience of flooding and knowledge of construction works like fences, walls and landscaping that may affect how water pools or flows.
A community consultation session will be held next Saturday, November 29, from 10am-12.30pm at Richard Lynch Senior Citizens Centre in Brunswick West.
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