Rising tide, erosion a threat to Port Phillip Bay's beachside suburbs (Victoria, Australia)
With the glittering Port Phillip Bay at its doorstep, Brighton is among Melbourne’s poshest and most expensive suburbs.
In the summer heat, hordes flock to south-east Melbourne suburb's beaches to cool off, cycle and walk along the water’s edge or launch a boat into the sea.
But the bay also poses an increasing threat to Brighton as Bayside Council mounts a frontline defence against the effects of climate change in the form of rising sea levels, storm surges and erosion.
At the North Road foreshore in Brighton the council wants to build new sea walls, extend protective rockwork and install a concrete “terrace” to hold back the encroaching water.
A foreshore masterplan warned that the suburb was increasingly vulnerable to extreme weather and flooding.
“Brighton’s susceptibility to coastal erosion is projected to increase as a result of climate change. As sea levels rise and storm severity increases, both storm surge levels and storm wave heights will also increase,” it said.
Similar scenes are playing out across Port Phillip Bay where councils are spending millions of dollars erecting defences to protect foreshores, properties and public infrastructure from the rising threat of climate change.
Nearby low-lying areas may be considered more vulnerable to flooding than Brighton. But the North Road foreshore masterplan, recently endorsed by the council, said waves were “overtopping” existing rock sea walls more frequently and damaging fences that were already in poor condition in many sections.
It warned that without protective works, the existing rock walls would be unable to withstand the heightened waves and increased storm severity, inundating pedestrian and cycling paths while eroding the foreshore.
“There will also be an increased likelihood of damage to properties and roads that are relatively low-lying in the area.”
Bayside Council is yet to determine the exact size of the extended sea walls but will spend about $3.5 million on the foreshore plan.
Deputy mayor Rob Grinter said erosion of beaches was an ongoing struggle, impacting the bay along its entire coast.
“If we don’t do something to address this impact of climate change now it is likely many of Bayside’s beautiful beaches and foreshore areas may be lost forever,” he said.
Further west, Hobsons Bay City Council will spend $2.1 million to protect Altona foreshore from the “damaging effects of climate change” by extending sea walls and raising their heights in two locations.
But that is just the start of a broader set of works to be carried out over coming years.
The council expects the sea level to rise by at least 8 centimetres by 2030 and 39 centimetres by 2070 in Altona and Williamstown.
Hobsons Bay mayor Jonathon Marsden said the council had developed a 10-year plan to protect the community, which includes raising more sea walls and renourishing beaches where erosion has set in.
“As a coastal community, Hobsons Bay is particularly vulnerable to the effects of climate change so [the] council is being proactive now and building the infrastructure that we will need to protect our community for years to come,” he said.
The council has also launched a trial with Melbourne University planting mangroves to protect the Altona foreshore from erosion.
The council hopes mangrove roots will help bind the soil while above ground the plants will ease the impact of wind and waves.
“One of the aims for this project is to raise awareness of nature-based systems which can be used to defend our coastline,” Cr Marsden said. “We hope that this innovative defence against coastal erosion can be used as a viable form of protection for all foreshores.”
A Victorian Environmental Assessment Council report released last month shows rising seas are threatening to encroach on low-lying parts of Melbourne within 20 years.
Mordialloc, Seaford, Point Cook, Frankston and St Kilda are among the suburbs deemed at risk.
The report cited a 20-centimetre sea level rise by 2040 and between 40 centimetres and one metre by the year, 2100.
City of Port Phillip mayor Dick Gross said the inner bayside suburb of Elwood was at the centre of his municipality’s flood problems, particularly when king tides, storms and water from the surrounding catchment came streaming in.
“The risk is absolutely tangible,” he said. “We have to do something about it.”
Cr Gross said some residents were still recovering from a downpour in 2016 that flooded houses and roads. He expected flooding of similar severity to happen more frequently.
“It’s really traumatic,” he said. “Your house stinks. You have to rip up carpet, you have to replace furniture and furnishings.”
The City of Kingston has been building rock retaining walls and textile barriers to protect sand dunes south of Mordialloc Creek.
The council’s general manager of city assets and environment, Daniel Freer, said properties in Carrum and Aspendale about four metres above sea level were protected by dunes that were vulnerable to erosion caused by higher tides and extreme storm surges.
“The biggest concerns for our council are the erosion of beaches and the potential for future storm surges to affect areas around the mouth of Mordialloc Creek,” he said.
Environment Victoria campaigns manager Nicholas Aberle said sea level rise would have a major impact on towns and cities.
“We have billions of dollars of infrastructure within metres of the ocean and at risk of being severely damaged,” Mr Aberle said.
"We're a nation of beach-lovers. It's how we are recognised internationally. But we risk losing many of our iconic beaches in our lifetime if we don't get serious about cutting our greenhouse emissions.”
The state government is conducting consultation for a new marine policy to protect the Victorian coastline from a range of threats, including those posed by climate change.
Environment Minister Lily D’Ambrosio said the policy would provide direction on dealing with the impacts of climate change, population growth and ageing coastal structures.
“All levels of government have a role to play in addressing these challenges - this policy will guide decision makers, including local councils and land managers in the planning and management of our marine and coastal environment,” she said.