On 14 February 2023, Cyclone Gabrielle made landfall across the east coast of Aotearoa New Zealand, a severe tropical cyclone that devastated parts of the North Island, taking out critical infrastructure systems and triggering a national state of emergency.
Beca Water Business Director Darren de Klerk said the extreme weather event and its impacts were unprecedented, with 13 of the 20 measurement sites registering the biggest flood on record, with rainfall in excess of 500mm falling within a six-hour period.
“The rainfall exceeded anything we’d ever seen. This brought a significant amount of water down our river catchments, spilling out over stop banks, causing widespread flooding. We have had a massive challenge with the amount of sediment and debris that came down the catchment,” he said.
“This debris caused a beaver-dam effect, blocking up bridges and riverways, causing further flooding. In some locations, bridges collapsed, causing an in-land tsunami scenario, as water was released. Unfortunately, eleven lives were lost, nine in Hawke’s Bay as a result of Cyclone Gabrielle. This is a devastating outcome.”
Stop bank infrastructure was overtopped, damaged and breached, lifelines like drinking and wastewater treatment plants were inundated, communities were flooded, bridges and roads were destroyed, power stations were taken out and telecommunications networks failed.
“A number of water and wastewater treatment plants were flooded. A number of our communities plants damaged, one in Napier was completely underwater, frying the electrical control room. Divers were sent to open bypass valves to stop surcharging back up the network,” de Klerk said.
“Stormwater systems were overwhelmed, too. Hundreds of homes were flooded as a result of the size of the event and the inability of the infrastructure to handle the event. In the Hastings region, thirteen bridges and six large were destroyed and many others requiring repairs, impacting the ability to cross the river in many locations.
“One of the biggest reflections was how wide-spread the impact was, beyond comprehension to be honest. It ranged from the north to the south of the east coast, hundreds of kilometers. The extent of the disaster has made the event so challenging to recover from.”
One of the lasting impacts of Cyclone Gabrielle has been how the event has refined resilience in the face of climate change, de Klerk said, with the history-making disaster opening up a whole new discussion around the location, the type and the level of service of assets in Aotearoa New Zealand.
“From a resilience point of view, asset owners are having to consider what resilience means for them and their communities in a post-cyclone environment. Cyclone Gabrielle has completely changed our design directions and has shifted our understanding of what a 1-in-100 year event actually is, and put the topic fresh in the minds of our communities,” he said.
“Community-level resilience is interesting in this context. Historically, each little community would have been equipped to look after itself. But have shifted to a more centralised model since the creation of the Civil Defence Emergency Management Act in 2002.
“Some communities still have an inherent independence. They responded and worked to look after themselves, knowing that emergency services wouldn’t be able to reach them for a while. The first week following the cyclone was truly chaotic, but community empowerment should be central to disaster mitigation and recovery.”
“In New Zealand, we have had a heavy focus on preparation for seismic events due to earthquake risk. We have had less focus on flooding. But this event has been game changing when it comes to disaster preparedness. We do not have much that’s comparable.”
de Klerk said all extreme weather events offer up learnings, but Cyclone Gabrielle imparted insights that must be considered if systems are to be built back to handle more intense levels of disruption, which is what climate change promises to bring.
“It’s vital we take advantage of the event to engage with the community around improvements. After events, communities are very interested in future protection, and it is much easier to engage with them once they have experienced an event like this,” he said.
“This is about using the recency of the event to create positive changes. Bringing everyone together and keeping up the momentum is key.”
“The honeymoon period of togetherness wears off after a little while. But we really want to be able to maintain that multi-faceted, multi-agency approach. Not just for the immediate response, but for the long-term recovery, planning and mitigation.”
While not ideal, extreme events test scenario planning, providing learnings about how to adapt moving forward, helping communities and utilities think about adaptive pathway planning, de Klerk said.
“From an asset owner resilience point of view, thinking about insurance cover is a big consideration. Getting the house in order for rainy day events makes a lot of difference when the damage is done and funding is needed to recover,” he said.
“The other learning is around how to build back. Do we build back like-for-like, or a betterment? As I said, the goal posts are shifting from a design basis of what a 1-in-100 year event is. So, what level of future event are we building for?
“Failing safely is a concept to seriously be considered, especially for some smaller communities. We can build assets knowing they are going to flood. If we design the system so that the community can maintain independence when things go wrong, that’s ideal.
“This approach challenges traditional thinking, but it might be the most cost-effective and resilient solution. It’s a fail-safe approach. How do we equip and empower communities to see the benefit in that and be okay with it?”
Looking at resilience further afield, Beca International & Asset Management Advisor Dean Taylor said the Pacific region has a lot of insight to offer, particularly in terms of considering context when building resilient systems and bolstering communities.
“Resilience is multifaceted. We have to think about how to prevent a problem, but also how to react when a problem occurs. How do we recover? But also, how do we adapt going forward?” he said.
“We often talk about resilience in technical terms, as an engineering problem, but how the system responds really does depend on context. We can build two identical water treatment plants in two different contexts and have completely different resilience outcomes.
“Context is really, really important for resilience; the people, the supply chains, the operating or enabling environment can all make a big difference around how well communities and systems bounce back from disruption.”
Taylor said the 2022 volcanic eruption in Tonga highlighted aspects of resilience in remote Pacific communities, including how simplicity is often undervalued.
“They’re remarkably resilient people, they got their systems back up and running without a lot of external help. This is because their systems are simple and effective within their specific context,” he said.
“We need to stand back at times and ask: how much do these systems really need to improve? And what are the hazards that might occur from trying to make improvements where they aren't needed? A lot of high tech equipment can be detrimental within certain contexts.
“From a people first perspective, we need to consider the whole environment. The operating environment, but also the capability of the people there and what they require to build capacity.”
Taylor said adaptive planning is coming to the fore within climate change mitigation efforts, an approach that’s proving to be useful due to the uncertainty involved.
“It’s misguided to think that there's one problem with one solution. Climate change is resulting in multiple problems with the need for multiple solutions. We need to look at a whole range of potential outcomes, but resist the urge to lock in a plan,” he said.
“We need to make sure people are aware of the risks and build in as much resilience as we can by not locking in major decisions until necessary.”
Furthermore, the lessons learned about context and resilience in the Pacific should be adapted within Australia, Taylor said, with many of the issues relating to remote service provision present here and in need of new thinking.
“It's been really interesting and challenging to modify the approach that we've got here and apply them to the Pacific. But this is not a one-way street. There are some incredible aspects of resilience that we can learn from Pacific nations to apply here in Australia,” he said.
“We actually need to learn the lessons of robust simple systems, capacity building for people and apply that now back to our regional communities.”