PHOTO: Pixabay

Cyclone taskforce will tackle managed retreat – Expert Reaction

The Cyclone Gabrielle Recovery Taskforce will cover issues to do with managed retreat, including who pays for it – as well as other climate adaptation and resilience issues.

Experts have said rebuilding some flood-damaged homes doesn’t make sense given the high risk of flooding in the future, while some residents are calling for voluntary buyouts after repeated and debilitating floods.

The SMC asked experts to discuss various aspects of managed retreat in Aotearoa, including its impact on Māori communities, and the roles that river management and landslide assessment can play.

Dr Christina Hanna, Lecturer, Environmental Planning, University of Waikato; Dr Raven Cretney, Postdoctoral Fellow, Environmental Planning, University of Waikato; and Professor Iain White, Environmental Planning Programme, University of Waikato, comment:

“The unfolding impacts of recent floods and Cyclone Gabrielle have focused the spotlight on the important role of managed retreats in reducing exposure to the impacts of climate change and disasters. Simply put, managed retreat represents land use change; relocating people, assets, activities, and taonga, where appropriate, from dangerous locations. It can also involve ecosystem migration or restoration to mitigate environmental harm and build adaptive capacity.

“Managed retreat is inevitable for some communities, public places and assets, and may be possible for some cultural and heritage sites across Aotearoa. For localities facing significant, recurrent harm and escalating risks, the questions pertaining to managed retreat are when, how, where to, and who pays?

“At present, managed retreats are socially and politically risky due to the lack of fit-for-purpose legislation and funding resources to enable effective and equitable outcomes. The proposed Climate Adaptation Act aims to address these technical, legal and financial issues.

“Even with a supportive policy environment, our research emphasises the scale of the challenges ahead. We must go beyond designing technical and legal mechanisms, to change social norms and expectations around property rights and resource management. This fundamentally involves re-imagining how we interact with places and environments as we adapt to climate change. Reconstructing our relationships with the environment to reflect changing risk, mātauranga Māori, justice, and space for nature is central to enabling managed retreats, and to avoid perpetual managed retreats. To do this, we need to look beyond the Climate Adaptation Act, to engage with broader institutional reform able to adjust our collective relationships with land, water, and property.”

Conflict of interest statements: “Christina Hanna receives funding from the Aotearoa New Zealand Government National Science Challenge: Resilience to Nature’s Challenges – Kia manawaroa – Ngā Ākina o Te Ao Tūroa. Christina also receives funding from the Ministry of Business, Innovation and Employment’s Endeavour Fund to research issues connected to flood risk mapping and better decision making. Raven Cretney receives funding from the Resilience to Nature’s Challenges National Science Challenge: Kia manawaroa – Ngā Ākina o Te Ao Tūro and the Biological Heritage National Science Challenge: Ngā Koiora Tuku Iho. Iain White receives funding from the Aotearoa New Zealand Government National Science Challenge: Resilience to Nature’s Challenges – Kia manawaroa – Ngā Ākina o Te Ao Tūroa. Iain White also receives funding from the Ministry of Business, Innovation and Employment’s Endeavour Fund to research issues connected to flood risk mapping and better decision making.”

Professor Bruce Glavovic, School of People, Environment and Planning, Massey University, comments:

“Cyclone Gabrielle has left a path of tragedy and devastation. Like all New Zealanders, my heart goes out to all who have had their lives turned upside down by Gabrielle. The outpouring of support is fantastic. But there is a long, hard recovery road ahead.

“We have learned much from recent disasters and recovery efforts. Heeding these lessons is crucial. Much can be done to enable a good, enduring recovery. But it is easy to unintentionally entrench the very conditions that predisposed communities to disaster in the first place.

“How we deal with this issue will profoundly shape our collective future – at every level of society.

“Managed retreat is an extremely confronting and complex issue – not least because of the deep cultural, spiritual, social and livelihood ties that we have to the places we live.

“Attention is now being focused on whether or not to allow rebuilding in places devastated by Gabrielle and likely to be exposed to future extreme events. But there are many obstacles to enable planned relocation. Not the least obstacle is insurance provisions that lock-in development patterns with stipulations that result in replacement of ‘like with like’.

“We need to avoid ad hoc decisions that result in some people relocating and some people rebuilding in hazardous locations.

“We cannot allow new development in obviously exposed localities. And hold to account those who permit dangerous development decisions, including legal liability for councils and decision-makers.

“Lives are at stake. 

“Action needs to be taken now. But we need to keep the distant future in mind, keeping options open that foster community well-being and resilience.

“Mātauranga Māori, local knowledge, and science and technical knowledge are key to building shared understanding about managed retreat.

“Ultimately, managed retreat is collective responsibility. It depends on strong bonds of trust and collaboration. We all have a role to play in future-proofing our flood-prone communities.

“The managed retreat challenge is now front and centre to the recovery of Gabrielle-impacted communities. And this challenge extends far beyond these communities. It is a challenge that faces all of us in Aotearoa New Zealand.”

See here for extended commentary from Professor Bruce Glavovic. 

No conflicts of interest declared.

Professor Merata Kawharu and Professor Janet Stephenson, Centre for Sustainability, University of Otago, comment:

“For Māori communities, the terms ‘managed retreat’ or ‘planned relocations’ can be deeply upsetting, as most are still affected by the legacy of historic forced ‘relocations’ away from their traditional lands and resources. Climate change can be seen as yet another impact of colonisation as it is driving more wedges between tangata and their whenua.

“Many Māori communities have marae, kāinga, wāhi tapu and other valued places that are already bring affected or are likely to be affected in coming years.

“For some communities, relocation is part of their own history, whereby settlements or marae have been shifted due to flooding or erosion in the past. They may see future relocations as a part of their tikanga, their traditional response to such challenges.

“Others are deeply opposed to idea of relocating marae or wāhi tapu, and wish to see these places protected and preserved where they currently are.

“Yet other communities are anticipating the need to relocate housing or marae in the future but are facing extremely challenging issues. Some hapū or iwi have limited land resources and may not necessarily have suitable land to relocate to that are still in their legal title, even if the lands that they may want to move to are their ancestral land. They can’t just go anywhere because their connections are to a specific area or region. Their only option may be to negotiate with relevant councils or government agencies for assistance with finding a suitable place and to help with the costs and logistics of relocating and rebuilding.

“Ultimately, the issue is about marae determining their futures on their terms. It is about maintaining mana in their lands and preserving the integrity of lands. These values are important wherever communities determine is the best place to live. It is also about who will bear the costs, whether that is costs of relocation or costs of structures to try to safeguard treasured places.

“Local, regional and central government agencies need to listen carefully to each community to hear their needs. Each will be different. And each will take commitment and innovative thinking to resolve complex issues.”

No conflicts of interest.

Jon Tunnicliffe, Senior Lecturer, School of Environment, University of Auckland, comments:

“New Zealand rivers are world-renowned for their dynamism. They evolve constantly in response to inputs of sediment and water, seeking to balance changing catchment conditions by adjusting their steepness or their channel pattern to accommodate floodwaters or episodic deliveries of sediment.

“Yet, we manage our rivers as though they were static. Engineered flood defenses are often deployed in an attempt to keep dynamic rivers fixed in a static configuration. This has enabled generations of New Zealanders to reap the benefits of rich and fertile alluvial soils and to reliably connect us with road, rail and other infrastructure. Flood defenses such as stop-banks, groynes, and sumps have greatly expanded our definition of developable land, but in the process of installing various restraints, we have also created risks. The current climate crisis is revealing the limitations of this river management paradigm. There will always be a role for flood defences, but without appropriate space for the river to adjust and to spill over in places, some rivers are likely to continue looking to regain their equilibrium – in spite of human restraints on their evolution. In the process, this gives rise to tragic consequences and hardship for whānau and communities.

“The digital scanning of New Zealand’s historical air-photo record provides an exceptional window into the past behaviour of rivers, and their legacy of disturbance and change. In addition, high-resolution laser scanning (LiDAR) reveals the contours of past river courses, and evidence of their mechanisms of change and natural adaptation. While there is no going back in time, we can use this information to model likely scenarios of river change in light of an intensifying climate regime and alterations of landcover upstream, and to look strategically at how future planning might take better account of the requirements of a living river.

“Recent storm and cyclone events are forcing us to reimagine our river management paradigm, and consider how we can respond to evolving river systems. The cutting edge of this science is not just the instrumentation and model algorithms of river metamorphosis, but developing new knowledge with mātauranga Māori expertise, and fostering engagement with mana whenua, local knowledge holders, property owners and citizens more broadly to accommodate river geomorphic and ecological processes. The combination of new scientific techniques, broader expertise, iwi, hapū and community engagement, and new techniques for informed and structured deliberative local and national conversations to improve our resilience and capacity to live with New Zealand’s dynamic rivers.

“When similar catastrophic flooding occurred along the Ottawa and St-Laurence river basins in Central Canada in 2018 and 2019 for instance, part of the provincial government’s response was to establish a transdisciplinary network of expertise and community know-how that combined universities, public research organisations, Indigenous leaders and local councils. It has been facilitating more informed decisions about where to defend, where to adapt and where to retreat, which in turn can make it (a bit) easier to figure out the how, the when and who pays.”

No conflict of interest.

Martin Brook, Associate Professor of Applied Geology, University of Auckland, and Chartered Geologist, comments:

“A clear understanding of geomorphological processes and landforms, including mapping of landslide hazards, should underpin any decisions about managed retreat and any new setback distances.

“There are several approaches that can be utilised. LiDAR digital elevation models (DEMs) provide a good basis for mapping the late Prof Oldrich Hungr’s 32 possible landslide types (and whether they are relict, or prone to reactivation due to rain or earthquakes). Slopes can be monitored from space using interferometric synthetic aperture radar (InSAR), as my EQC-funded group did in Gisborne from 2016-2021. In Europe, such a service is available online here for anyone to look at, and can be an excellent planning tool. Landslide susceptibility modelling can also be undertaken to identify areas most likely to be affected by landslides. Runout modelling can also be undertaken to determine possible areas of inundation by mobile landslides.

“However, landslide effects can also be mitigated. For example, GNS developed a tool to predict regional landsliding on the basis of impending rain events. Also, in-situ slope monitoring technology can provide real-time monitoring of active slopes, providing a time window for evacuation, where possible. Slope engineering can stabilise some slopes, within financial reason.

“However, it’s important that the baby isn’t thrown out with the bathwater, and getting the geomorphology right is important. As an example, the village of Parton in Cumbria, UK, was temporarily evacuated in August 2021 due to concerns of a possible landslide, a klaxon warning system was installed, and the school was only reopened 14 months later. However, after substantial geotechnical investigations and monitoring commissioned by Cumbria County Council, it was found that there was no evidence for any recent slope instability at all. Indeed, the ‘tension cracks’ thought to be indicative of impending landslides were actually shrinkage cracks due to the clay-rich soils drying out in a hot UK summer.

“So, striking the right balance between planning decisions and mitigating landslide risk, is important in any managed retreat process.”

Conflict of interest statement: “I have received funding from EQC, MBIE and the Royal Society of New Zealand.”