Local councils across Australia and New Zealand are increasingly facing the problem of coastal erosion and land instability from rising sea levels. What was once a rare event, has evolved into a persistent trend that will likely continue to accelerate in coming decades.
The scale of this challenge and the impact on local infrastructure can be seen in coastal areas across Australia and New Zealand. Between 2020 and 2025, the New South Wales coastal town of Byron Bay experienced a number of significant storm events and cyclones, many of which brought higher than normal tides, large swells, and strong winds. The resulting damage included the loss of significant volumes of sand, lowering of the beach profile, loss of dune vegetation, damage to beach access ways, loss of signage, and damage to walkways.
Similar patterns have been seen in New Zealand. The shoreline of Hawkes Bay in the North Island has experienced chronic erosion since the early 1970s, with an average shoreline loss of 0.3m to 0.7m each year. Equally, the town of Amberley Beach in Hurunui District Council on the South Island has experienced such significant flooding from coastal erosion that the Council has proposed a controversial land-swap initiative to potentially relocate more than 100 homes away from the encroaching sea.
These threats present a major infrastructure challenge and can have a significant impact on critical services. Local governments are responsible for the majority of ‘at-risk’ infrastructure, such as roads, car parks, bridges, parks, wastewater pipes, stormwater drains, and public amenities.
Current estimates suggest that over $226 billion in Australian assets are at risk from coastal erosion and sea level inundation. The at risk assets include 26,000 to 33,000km of roads, 1,200 to 1,500km of rail lines, and wastewater pipes and stormwater drains which, when compromised by saltwater intrusion, can lead to service failures further inland.
Echoing this, the Insurance Council of Australia has suggested that Governments will need to invest approximately $30 billion over the next 50 years in large-scale coastal protection and adaptation projects.
Traditionally coastal erosion has been managed with hard infrastructure such as sea walls and breakwaters. However, while these structures are effective in safeguarding buildings and roads, they often inadvertently shift the erosion problem to other locations along the coast.
In response to these unintended consequences, councils are increasingly pivoting toward nature-based alternatives that work with, rather than against, coastal dynamics. These ‘soft’ engineering approaches, such as large-scale beach nourishment and dune restoration, attempt to mimic natural buffers and aim to absorb wave energy during storm events.
A successful example of this has been seen in the Netherlands and the development of the ‘Zandmotor’ (Sand Motor). This is a proactive approach to sediment management in which the government deposited a massive 21.5 million cubic meters of sand in a single hook-shaped peninsula in 2011, rather than depositing smaller, repetitive beach nourishments. Since then, natural wind, waves and currents have gradually distributed the sand along the coast. It was expected that the Zandmotor would have a lifespan of 20 years, however ongoing research has shown that it will be much longer.
Closer to home, the NSW City of Newcastle has rolled out the Stockton Coastal Management Program to provide a coordinated and agile approach to the management of Stockton Beach. The beach is located on a sand peninsula, and is a dynamic coastal environment that has experienced ongoing, significant coastal erosion. The Council has also opted to use mass sand nourishment and regular sand top-ups to restore a sandy buffer back to its previous condition. The Council is also conscious of the need for a possible ‘retreat’ for some built structures. To date it has already moved 16 cabins from the Stockton Beach Holiday Park to higher ground as they were at risk of collapse from erosion.
Councils in New Zealand have adopted the Dynamic Adaptive Policy Pathway (DAPP), in which they create a ‘map’ of future decisions which will be triggered by potential coastal changes (for example a 20cm sea-level rise). The DAPP addresses the uncertainty of future events, and allows for adaptive responses.
Hawke’s Bay was one of the first regions in New Zealand to adopt this approach. Their DAPP identified different potential solutions for different regions. In Napier, the emphasis has been on large-scale sand nourishment to protect build assets. In Haumoana, which has a lower population density and greater erosion, managed retreat was laid out as an option earlier in the DAPP timeline.
Proactive coastal management solutions often require local government to look beyond the immediate budget cycles to be able to adapt to changing environmental conditions. Shifting the way we manage these areas, will hopefully ensure our communities are resilient and our coastlines remain accessible and enjoyable resource for future generations.