Tough decisions still need to be made but leading experts say NZ can build a "resilient society".

Preventing climate change may largely be beyond the human race now – but a global infrastructure consultancy says New Zealand still has time for innovative, future-oriented decisions to build and prepare more resilient communities.

Dr Rowan Dixon, senior environmental consultant for WSP Opus, says international cities such as Jakarta, Rotterdam and Miami are facing rising sea levels and displaced residents while some New Zealand cities can expect similar impacts – and need to act fast.

The window of opportunity for innovative thinking to combat the effects of climate change is narrowing, he says, and tough decisions need to be made.

"Our aging infrastructure wasn't built to cope with this many people and the impacts of climate change – and the signs of stress are evident," he says. "For example, roads designed to need repair once a decade are now being repeatedly flooded and require repair every two to three years.

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"That's pushing budgets out and is causing very real challenges. So at what point do you stop trying to get rid of unwanted water and start designing for it?"

Like WSP Opus's work in Washington DC, where the First Street Tunnel – an underground tunnel designed to relieve flooding and sewer overflows – was hit in 2012 by a series of powerful climate-change storms which caused the streets to flow knee-deep with sewage.

They were called in to halt the flooding of Washington's Bloomingdale and Le Droit Park, inundated when manhole covers burst open and millions of gallons of sewage and stormwater from the tunnel escaped over the neighbourhoods.

WSP Opus designed the tunnel upgrade, completed using a giant tunnel boring machine known as "Lucy" – an even bigger version of "Alice", used to hollow out Auckland's Waterview tunnel.

Such innovative 'hard' engineering approaches might the most appropriate, but not always. Dixon emphasises the importance of smart and adaptive approaches to planning communities and infrastructure.

WSP Opus has partnered with the UK motorway provider, Highways England, to develop a climate assessment methodology for all roads and bridges, about 7000km worth. The methodology addresses the resilience of roads and bridges to the effects of climate change and the carbon emissions from their construction and maintenance – helping Highways England reduce their carbon footprint. This approach is expected to spread across the UK's transport infrastructure industry.

Dixon says such clever thinking is needed when addressing the effects of climate change: It begins by embedding our new climate and environmental realities into our design thinking and starting with the end in mind. What do we want our future to look like and how do we get there?"

This adaptation mindset is playing out in New Zealand and with good reason. In recent times, cyclones Gita and Debbie have wrought havoc, as has the increasing frequency of king tides with storms and rivers breaking their banks, damaging hundreds of homes.
This has already resulted in changes to regulations in South Dunedin, where the floors of all new homes in flood-prone areas are required to be at least 40cm higher than the 2015 flood waters reached.

Many other areas of New Zealand, including parts of Auckland, Thames, Napier, Gisborne, Christchurch's Sumner and Southshore, the Wellington CBD and Hutt motorway, are being affected by rising sea levels.

Liam Foster, water sector leader at WSP Opus, says: "These are big problems we are facing," says Foster. "Solutions require collaboration across sectors that may not have worked closely together before. Most importantly, it must keep the community's interests at heart.

Bringing everyone along together can be a challenge but is crucial. From an engineering perspective, strategic flood risk management and sustainable drainage are some of the tools we can use."

Foster believes a good starting point would be a national flood risk assessment that would deliver an understanding of New Zealand's vulnerability and, once in place, "we can undertake local, regional and national climate change risk assessments to determine how to make the best out of opportunities presented by climate change – as opposed to being reactive and responsive to the unforeseen impact of disruption."

Options include "managed retreat", where communities adapt to flood risk by choosing new land use for flood-prone areas. One example was the Wallasea Island reserve in Essex, UK – previously farmland but now re-adapted as a wetlands wildlife reserve by removing the sea wall and flooding hundreds of hectares of land.

Other options included "holding the line" where communities could opt to maintain the status quo as best possible or "advancing the line" – where extra efforts are made to keep sea or rivers at bay.

An example of advancing the line in New Zealand was the highway near Kaikoura, where the earthquake and slips had seen the road damaged and closed. Foster says the clever response was "to advance the line by building the road further away from the hills and more out to the sea – but building it higher so it is at less risk of flooding.

"Each of these options has its place and, if coordinated, will improve our wellbeing and economic growth into the future."

For more information on our sector leaders click below:
Dr Rowan Dixon
Liam Foster