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The coastal town that will have to retreat – or build up – as seas rise
By Adam Carey
Low-lying coastal towns around Western Port could eventually be forced into a “strategic retreat” from the advancing ocean in the face of an existential threat from rising sea levels and damaging storm surges.
Hundreds of homes, dozens of businesses and community assets – including a primary school, maternal health centre, a regional airport and a major highway – south-east of Melbourne face a growing threat of inundation between now and the end of the century as sea levels rise by a projected 80 centimetres.
Tooradin resident Di Loft on the foreshore of the town, which is predicted to become increasingly vulnerable to inundation.Credit: Chris Hopkins
The growing risk to Western Port’s unique and biodiverse northern coastline is revealed in a 164-page report commissioned by the City of Casey, one of Melbourne’s fastest-growing local government areas.
It details the increasing likelihood and cost of inundation and erosion between now and 2100, and the difficult choices communities will face as the sea reclaims the former swampland on which the region is built.
The state government-funded analysis has found the coastal communities of Western Port will become increasingly vulnerable to inundation over the next 20 to 70 years, and risk suffering hundreds of millions of dollars in flood damage each year unless urgent mitigation steps are taken.
Tooradin, a 150-year-old fishing town of more than 1700 people, faces an “unacceptable” long-term risk of flooding that requires immediate action, including preparing for a potential “strategic retreat” of key infrastructure predicted to begin to go underwater between 2040 and 2100.
The town’s primary school, maternal and child health centre, airport, main roads, bridges and footpaths are at increasing risk of inundation and projected to be flooded during a major storm surge by 2100.
Eighty-four per cent of the township’s homes could be flooded in a one-in-100-chance storm, as would most of the town’s commercial and industrial buildings. In total, 884 buildings in Tooradin are at risk of inundation and action is required now to prepare for this, the report says.
“Substantial and transformational adaptation planning is required from present-day onwards for Tooradin,” the report says.
“This will seek to retain and enhance some of the natural values and assets key to local resilience, and try to maintain liveability, safety and viability of the Tooradin community into the future.”
The report warns that in the long term, all of Casey’s coastal communities will need to adapt to rising sea levels.
Other smaller communities in Warneet, Cannon Creek and Blind Bight also face varying degrees of exposure to inundation and erosion.
The report proposes more than 20 possible “coastal hazard adaptation actions”, including relocating infrastructure, changing planning controls to limit or stop new developments, and a host of engineering responses including building seawalls and upgrading roads and drainage.
It says there is still time to act to protect the community against rising seas, with many of the worst risks of inundation due to increase between 2040 and 2070, when sea levels will rise between 20 and 50 centimetres, according to the modelling.
By 2100, a potential 80-centimetre sea level rise is projected.
The region’s agricultural productivity will also decline as soils and waterways become saltier.
“For Casey, increases in groundwater salinity will have a major impact on agricultural parcels of land and their productivity (with lower-than-average yields expected).”
The coastal area is home to native mangroves, seagrass beds and salt marshes that provide refuge to endangered shorebird species and fish. Much of it is protected under an international environmental convention called Ramsar.
Studies of the Western Port coastline show that mangroves are already moving landward.Credit: Chris Hopkins
Professor David Kennedy, a coastal geographer with the University of Melbourne, said long-term studies of the Western Port coastline show that mangroves are already moving landward in response to sea level rises.
“We are seeing the high tide get higher … we do have undeniable evidence that the mangroves are shifting landward, and we are seeing changes as the shoreline is wanting to move inland due to climate change and sea level rise,” he said.
Kennedy said the rising sea level presented “two futures” for Tooradin.
“Really, the two options coming forward are either move the town, and that’s a managed retreat, or build it up and eventually it’s hiding behind levees.”
That would come at a cost to the natural environment, Kennedy said.
“If you end up with a coast that’s just concrete walls, well, you’re going to have lost all that biodiversity and breeding grounds for fish.”
Tooradin resident Di Loft has co-owned the town’s newsagency for 18 years. She has seen it flood just once, when the South Gippsland Highway was temporarily closed off between Tooradin and Koo Wee Rup following heavy rain.
Loft, who lives in a low-lying part of Tooradin between the highway and the bay, said the most noticeable change regarding sea level rise was in council permits, which require new builds to be done on raised ground.
Tooradin faces a high risk of costly flooding and erosion as sea levels rise in the coming decades. Credit: Chris Hopkins
When a neighbour recently lost their shed in a fire, the council required them to build a replacement on concrete footings more than a metre above the ground.
The study, funded by the Department of Transport and Planning, and completed by environmental consultants Alluvium and economic consultants NC Economics, found that without adaptation, the cost of average annual damage from inundation in Casey’s coastal communities is projected to rise to $113 million by 2040 and about $300 million by 2100.
The Local Government Act requires councils to inform communities of potential risks related to climate change, and ensure decisions are informed by these risks.
Casey’s chair of administrators, Noelene Duff, said the council’s draft coastal framework “aims to enhance the resilience of the region’s coastal areas to changing climatic conditions”.
“It seeks to provide strategic direction for coastal planning, recommendations for adaptation pathways, and to inform decision-making on how to respond to increasing coastal hazard risks,” Duff said.
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