The threat of rising sea levels is becoming front of mind for coastal communities around Australia and New Zealand, with a new report on the impact to local government infrastructure revealing alarming figures. 

The Local Government New Zealand (LGNZ) report revealed the potential devastation rising sea levels could create. Released in late January, Vulnerable: The quantum of local government infrastructure exposed to sea level rise found as much as $14 billion of local government infrastructure could be at risk.  

The research, developed in conjunction with environmental and engineering consultancy Tonkin + Taylor, modelled various sea level rise scenarios using LiDAR and other topographical data from 62 councils.

The report showed that $2.7 billion of roads, waters and building infrastructure is at risk from as little as a 0.5m rise in sea levels. The value of at risk infrastructure ramped up sharply at each increment of sea level rise, with the data showing:

• $5.1 billion is at risk at 1m
• $7.8 is at risk at 1.5m
• $14.1 billion is at risk at 3m

LGNZ President Dave Cull said the report “paints a really stark picture for local communities”.

“Until now, councils have not had accurate information on the type, amount and replacement value of their infrastructure exposed to sea level rise, and therefore if and where planning should be prioritised,” Cull said.

“Many councils are already experiencing the impact of sea level rise, most notably in Bay of Plenty, the West Coast, South Dunedin and Hawke’s Bay.

“We need to urgently ramp up work on New Zealand’s adaptation framework. As a small country our efforts in the mitigation space – while necessary – are not going to meaningfully move the dial on global carbon emissions.  But changes in the climate will definitely impact us, principally in the form of rising sea levels as two-third of all New Zealanders live within five kilometres of the sea.”

The report makes four key recommendations:

• Local government leads a national conversation about the level of local government services currently provided and what can be maintained in the short (1–10 years), medium (10–30 years) and long-term (30+ years) as sea levels rise.
• Central and local government partner to establish a National Climate Change Adaptation Fund to ensure that costs of adaptation are shared equally, and do not over impact lower socioeconomic households.
• Establish a Local Government Risk Agency to help councils understand and factor climate change risks into their planning, decision-making and procurement frameworks.
• Local government team up with owners and users of exposed infrastructure to create a National Master Plan, setting out options, priorities and opportunities for responding to sea level rise.

“Local councils have for many years led the policy debate around climate change adaptation in New Zealand.  We are literally on the front line, and have been engaging with residents, iwi, and businesses who are exposed to rising sea levels, but the threat is too big for us to fight alone,” Cull said.

How councils are responding

Hastings District Council, Napier City Council and Hawke's Bay Regional Council are leading the way in the area of climate change adaptation and have been working together to tackle the issue, Stuff reports. 

In 2014 the councils agreed to work together to establish what sections of their coast were affected, how they were affected and possible solutions.

The strategy looks at the coast between the cape and Tangoio, north of Napier. It splits it into 15 cells, predicts the effect of coastal erosion in 50 and 100 years, and proposes options of responses.

Called 'pathways', these responses can include renourishment, groynes, sea walls or managed retreat.

Starting the conversation

Of course, it’s vital that any decisions made with regard to sea-level rise adaptation are communicated in the right way to residents.

Hawkes Bay Regional Councillor and Head of Strategy Peter Beaven told Stuff that getting community representatives appointed to the group early on, holding public meetings and giving affected people access to experts has been critical in getting to the current stage.

In Australia, a Noosa Council community forum in tackling the effects of sea-level rise favoured nature-based solutions, such as dune restoration and sand-recycling, with built structures such as rock walls deemed a 'last resort'.

"There was strong support for ‘nature-based’ measures such as beach nourishment and dune revegetation to bolster coastal areas against erosion," Council's Climate Change Project Coordinator Grant Hinner said.

"The feedback is largely consistent with that from our earlier consultation, with the community placing significant value on the natural state of Noosa Shire's coastal areas."

Feedback will inform development of Noosa's Coastal Hazards Adaption Plan (CHAP), which Council hopes to release in draft form for community feedback in a few months.

IPWEA guidance

Developed in collaboration with Northern Beaches Council, IPWEA’s publication Practice Note 12.1: Climate Change Impacts on the Useful Life of Infrastructure proposes alternate and resilient designs in response to impacts such as rising sea levels and increased extreme weather events for assets like community facilities, roads and stormwater outlets.

Northern Beaches Council put PN 12.1’s principles were put to the test in a number of real-world case studies, including an upgrade to Macpherson Street in Warriewood which had a history of inundation during heavy rain events, and the rebuilding of the amenities building on Marine Parade in Manly, which was damaged during the June 2016 storms. 

The collaborative project and publication were recognised with a Keep Australia Beautiful NSW Response to Climate Change Award in 2018.

Purchase PN 12.1 here. 

Read more about resilience and adaptation against rising sea levels in the next edition of inspire magazine, out in March.