Heavy rain warnings have been issued for the top of the South Island for Thursday.
The warnings come as the region recovers from heavy rain and flooding on Friday and Saturday.
The SMC asked experts for comment. See here for previous expert comments on repeated flooding events around NZ.
Dr Emily Lane, Principal Scientist – Natural Hazards and Hydrodynamics, Earth Sciences New Zealand, comments:
“Flooding is Aotearoa New Zealand’s most frequent hazard and one of its most costly. Treasury estimates that Cyclone Hale, the Auckland Anniversary Floods and Cyclone Gabrielle caused up to $14.5 billion of damage. While that was an exceptional year, on average we could face around $200 million annually in damage to buildings alone. The recent events in the Nelson and Marlborough regions emphasise that flooding is a nationwide problem.
“Climate change projections show extreme rainfall events are likely to become more frequent and more severe. To minimise our exposure to flooding, we need to both mitigate carbon emissions to ensure that global temperature increases are kept to a minimum and adapt to be ready to face this future flooding. To do this effectively we need consistent national information on current and future flooding risk, and to work together at national, regional and local scales.
“The MBIE-funded Endeavour programme Mā te Haumaru ō te Wai: Flood Resilience Aotearoa has been working to map New Zealand’s flood hazard and its impacts on our built environment, both currently and as our climate warms. The results from this project (likely interactive maps) will be published later this year. This work supports that of regional councils – which focus on individual regions – by putting a national lens over the problem.
“This mapping work has been primarily done by NIWA, which is now merged with GNS Science into Earth Sciences New Zealand. This merger, which will incorporate MetService too, will also help improve New Zealand’s flood resilience by providing a one-stop shop for both weather and geological hazards.”
No conflicts of interest.
Dr Judy Lawrence, Adjunct Professor at NZ Climate Change Institute and Antarctic Research Centre, Te Herenga Waka Victoria University of Wellington, comments:
“Climate change and where it’s taking us has been absent in the reporting to date, as has inquiry into the time it took and the reasons for Marlborough Council to discover Kaikoura earthquake damage to stopbanks.
“Is it that there are no funds to telemeter the stopbanks for potential failure conditions or lack of staff or expertise monitoring them? If monitoring responsibilities are shifted how will proactive monitoring practically be carried out?
“What are the dynamic adaptive pathways for flood risk management that move us from a protect and react paradigm to a dynamic anticipatory paradigm? New Zealand has the tools to do this. This is sorely needed as climate change and where we live exposes us to greater risks including financial and social risks.”
Conflict of interest statement: “I am a Climate Change Commissioner but I am responding as an expert in my VUW role.”
Dr Lauren Vinnell, Senior Lecturer of Emergency Management, Joint Centre for Disaster Research, Massey University, comments:
“Any experience of flooding can have harmful psychological impacts, but we know that it’s even worse when people go through multiple events, especially back to back like we’re starting to see more often. Unfortunately, it looks like repeated floods are only going to get more common so we need to start preparing for this. We need more investment in infrastructure to help reduce the impacts, like making sure we’re rebuilding with resilience in mind – stronger and in safer places when possible.
“For those experiencing flooding, always prioritise your safety first and if in doubt, get out. If you can, try to remember what helped you to get through and what you would have liked to have known or had ready to go, so that you can be more prepared for next time.”
No conflicts of interest.
Dr Daithi Stone, Climate Scientist, Earth Sciences New Zealand, comments:
“The top of the South Island has been hit hard lately, and unfortunately this is forecast to continue this week. Often storms over the Tasman bring water from a northwesterly direction, meaning that the West Coast bears the brunt. But this week’s storms have brought the water from a northerly direction, meaning Tasman and Marlborough have taken the hit. Moreover, last week’s storm stalled for a time, resulting in some locations getting more than 400 mm of rain within two days.
“How much was climate change implicated in these events? This is complex, akin to how hard it can be to forecast these weather systems and expand that over decades. In short, we don’t know at the moment. However the question of whether climate change is affecting the quantity of rain in a storm is more straightforward. Warmer air can hold more water – the warming we have already seen equates to about 10% more water. This means we would expect 10% more rain to fall in these types of storms. So while we do not yet know if climate change is changing the frequency or behaviour of the storms, it does mean they are delivering more rain.”
No conflicts of interest.
Dr Jon Tunnicliffe, Associate Professor in river science, University of Auckland, comments:
“In rural New Zealand, the cycle of flood disaster and costly recovery is becoming all too familiar. Breaking the cycle demands a holistic, catchment-wide approach that combines nature-based and engineered interventions. Managing runoff at its source through contour bunds, weirs and riparian buffers slows water flow and enhances infiltration. Strategic afforestation—in shelterbelts, woodlots and on steeper hill country—further intercepts rainfall and reduces peak flows. Reviving and reconnecting floodplains and wetlands restores natural water storage, attenuating smaller to mid-size floods. Strategic setback of stop banks and targeted excavation create room for rivers to expand safely, while restored or constructed wetlands intercept runoff, trapping sediment and debris before they enter waterways.
“Success hinges on broad partnership among land-owners, iwi, farmers, infrastructure managers and local councils. Collaborative planning forums can map priority sub-catchments, share costs and responsibilities, and integrate Mātauranga Māori with scientific design. Incentive schemes—such as rates relief for on-farm wetlands—encourage uptake, while coordinated maintenance and monitoring ensure long-term resilience.
“Though no strategy can eliminate the impacts of every extreme storm, this mosaic of solutions dramatically diminishes the severity of mid-range floods and may soften the blow of larger events. As climate change drives more intense and frequent downpours, unified action across catchments becomes not only an environmental imperative but a shared economic and social investment in the future of rural Aotearoa.”
Conflict of interest statement: “No conflicts of interest. My work on Nature-Based Solutions for flooding issues is support by MfE.”
Associate Professor Silvia Serrao-Neumann and Dr Christina Hanna, Environmental Planning Programme, University of Waikato, comment:
“Climate change is intensifying the frequency and severity of flooding across Aotearoa New Zealand, yet current land use planning and flood risk management practices remain outdated and rigid. The country’s fragmented flood governance structure leads to inconsistent flood risk evaluations and policy responses across different regions.
“The absence of a unified national strategy for riverine flood management has created a patchwork system characterized by: significant variation in flood hazard modelling; inconsistent policy frameworks with uneven implementation of risk-based approaches; non-standardized public information that hampers effective risk communication; conflicting regulations due to misaligned legislation; and limited capacity within local governments, highlighting the need for stronger national support.
“Poor communication of uncertainty and the lack of directive national guidance undermine communities’ ability to prepare for future and escalating flood risks. Dependence on single-probability forecasts and static planning can entrench flood risk by disregarding dynamic flood behaviours and probabilities in a changing climate.
“As flood risks continue to grow, Aotearoa New Zealand urgently requires a consistent, nationwide approach to riverine flood policy to ensure fair and effective risk management across all regions.”
Conflict of interest statement: “We both receive funding from the MBIE Endeavour funded programme Mā te haumaru ō nga puna wai ō Rākaihautū ka ora mo ake tonu: Increasing flood resilience across Aotearoa. A/Prof Serrao-Neumann also receives funding from the Natural Hazards Commission.”