As the Prime Minister visits Westport, the town faces the difficult decision of whether to rebuild or withdraw after the recent devastating floods. Government intervention and insurance can help if it chooses a planned retreat.

West Coast people are a stoic bunch, admirable for their gritty, communal sense of independence. Wedged between mountains, rivers and sea, they enjoy a unique sense of place. As last week’s one-in-100-year Westport floods attest, they are also – like many New Zealanders – becoming increasingly vulnerable to climate change.

The flood has been reported to be the largest in Westport since 1926. Some 400 houses have been “red-stickered”, and more than 100 are likely to remain uninhabitable. About 1,000 people have been displaced, their water-logged, muddy belongings piled high on the roadside in readiness to be dumped.

An enduring image is that of a local man wading through thigh-deep floodwaters, towing his few salvageable belongings in a kayak. His home was a write-off. Where to from here? He had no idea.

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Before Westport and its community can be restored, there are many hurdles to be overcome, many conversations to be had. Critically, climate change and its impacts must not be viewed in isolation.

There is a plethora of interdependencies between the effects of climate change and the entire natural hazard scape. Before embarking on a programme of returning the residential properties back to how and where they were before the disaster, we need to look at the cost of protecting these properties and what the wider natural hazard scape looks like.

Are the properties vulnerable to liquefaction and lateral spreading under seismic shaking? Are the properties vulnerable to sea level rise? Tsunami? Storm surge?”

The world has become more complex with climate change, and there is no getting back to normal. We are in reality – and always have been – on a continuum of natural change that is occurring all around us. That’s something we in the “Shaky Isles” forget at our peril.

Climate change is fundamentally changing some natural hazard events. This means that understanding the past may no longer equip us with the information to manage the future.

Two rotations of Civil Defence volunteers from Canterbury’s NZ Response Teams were able to use their experience from the Christchurch earthquakes, helping on the ground in Westport, working alongside the USAR Task Force, the NZ Defence Force and LandSAR. Photo: Buller Emergency Management

What we understood as a once in a lifetime event may be something we experience several to many times over the next few decades due to climate change. We are also increasingly becoming aware of the interconnected nature of some of our hazards, and that it is no longer appropriate to consider one hazard, and job done.

We need to think about many possible hazards and their consequences.

Our knowledge and understanding of natural hazards and their consequences can help us. Considering a range of possible scenarios, rather than a single design event, will help us to understand the potential consequences and “tipping point”. In turn, this will enable us to have more confidence in outcomes and to make better decisions for our environment and communities.

Planned retreat, although upsetting to many people, may form just one part of the overall solution.

Lessons can nonetheless be learned from the Canterbury earthquakes of 2010/11.

After natural disasters occur, it has been normal political practice to reassure the affected community that life will get back to “normal” as soon as possible.

This thinking changed after the second Christchurch earthquake in February 2011. The question then became should rebuilding occur in the same locations? Why rebuild in areas of multiple natural hazard risk, particularly if the vulnerability to those hazards was increasing?

As the flood waters receded from Westport, the extent of the damage became apparent. Photo: Buller Emergency Management

The high level of residential insurance cover in Canterbury provided an opportunity to withdraw from the areas at highest risk at the least economic cost. Christchurch’s “new normal” included a residential red zone, the first major withdrawal from a residential zone in New Zealand.

Over 7000 properties were sold to the Government, which in turn claimed back the insurance monies. Whilst it would have involved a significantly lower social and environmental cost to have withdrawn from these areas before disaster struck, natural disasters do provide an opportunity to evaluate whether rebuilding or withdrawal is the best use of financial resources.

Back to Westport and the problem at hand. In 2017, locals baulked at the cost of a $10 million flood protection scheme. In light of the floods, the idea is back in the limelight. But will it be enough?

Failure to repel floodwaters in Edgecumbe and Franz Josef show that building stop-banks is not necessarily the answer.

Westport’s floods clean-up has been long, painful and frequently interrupted by more heavy rain. Photo: Buller Emergency Management

In the 1970s the phrase building bigger disasters was coined to alert the public and politicians to the risks associated with building or raising flood defences such as stop-banks in the belief that putting more buildings, infrastructure and people on low lying ground on the other side was safe.

However, it was pointed out that a larger flood than the defences were designed for would inevitably overwhelm them and flood the “protected” land, thereby creating a bigger disaster.

If Westport is to have a more sustainable and resilient future, the community needs to start adapting to its existing natural hazard threats, many of which are dynamic and getting worse.

Planned retreat, although upsetting to many people, may form just one part of the overall solution.

More and more, scientists and engineers are leaning towards working with, rather than against, nature. Using nature-based and hybrid solutions to protect homes, lives and livelihoods.

With natural disaster insurance cover currently available it is important to take stock and, rather than attempting to recreate the past, look to the optimal future state of what Westport could look like.

Tonkin + Taylor geotechnical consultant Nick Rogers QSO specialises in in the field of natural hazard resilience and risk.

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