Mā te haumaru ō nga puna wai ō Rākaihautū ka ora mo ake tonu: Increasing flood resilience across Aotearoa

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Mā te haumaru ō nga puna wai ō Rākaihautū ka ora mo ake tonu: Increasing flood resilience across Aotearoa

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A national flood inundation hazard and risk assessment for Aotearoa New Zealand

In Aotearoa, our regular flood clean-up bills are topped only by much less frequent earthquakes. And with a warming climate and rising seas, flooding is expected to become more severe and more frequent. 

This five-year NIWA-led research programme will develop a system to map flood hazard consistently across the whole country. It will reveal how our flood risk might change over the next 100 years because of changes to rainfall and sea level from climate change, as well as due to land-use changes.

One of the outcomes will be the first, nationally-consistent, flood inundation hazard and risk assessment for Aotearoa New Zealand. Mapping national flood risk under current and future climates will provide a valuable resource for people undertaking future risk assessments. 

The research will investigate flood exposure according to type of land use, as well as risk to buildings, infrastructure networks, and long-term sustainability of flood schemes or defences. 

It will also provide a forum for researchers, iwi, stakeholders and government to discuss flood inundation hazard and risk and to co-develop strategies for a more flood resilient Aotearoa. The team will also work with case study communities to understand how they react to increasing flood hazard due to climate change and to help them develop adaptation strategies.

“Currently, we don’t have a clear understanding of the national flood hazard and risk across Aotearoa – either now or in the future. Critical decisions about mitigating and adapting to climate change are being made in this knowledge vacuum”

Emily Lane, NIWA Resilience to Hazards Programme Leader

Introductory video

The following video introduces the research programme and the case study partnering with Wairewa Runanga:

Programme overview

Working with Māori

Vision Mātauranga is at the heart of this research programme. The researchers are working with the hapū of Wairewa Rūnanga, Kāti Mako and Ngāti Irakehu, to explore their knowledge of flooding and to develop a plan to enhance the sustainability of their taonga. The programme outputs will also feed into the development of the Wairewa Rūnanga climate change strategy. The knowledge developed here will provide a template for other hapū and iwi to use to understand their flood risk.

Quantifying and communicating uncertainty

There is inherent uncertainty in the science underpinning many parts of this programme. In addition, making informed decisions today that account for future uncertainty while providing communities with homes and facilities they need is a pressing challenge for society. An overarching theme across this research programme will focus on uncertainty, and specifically quantifying and communicating uncertainty. This will be led by Matthew Wilson of the University of Canterbury, who helped develop the models used in UK national flood assessments.

Research aim 1: National flood mapping 

Led by Emily Lane, NIWA

This part of the project will result in the development of a flood database containing consistent flood hazard maps for a range of Annual Exceedance Probabilities (AEP) covering every catchment in the country. This will include considering the effects of climate change on both the intensity, as well as temporal and spatial structure of the storms, through analysis of new high-resolution weather modelling and observations. Results will be validated against historical floods in specific catchments.

Objectives of research aim 1:

  • Set up a semi-automated system that can develop consistent flood hazard maps for all Aotearoa New Zealand under current and future climates.
  • Collate historic flood photos and information.
  • Investigate hybrid machine-learning/hydrodynamic approaches to flood modelling.

Research aim 2: Flood risk to the built environment

Led by Ryan Paulik, NIWA

RA2 will see the development of a dynamic flood risk model that will assess flood exposure and risk at national to local (i.e., floodplain) levels.The researchers will co-design risk analysis methodologies with leading flood risk researchers, public and private sector flood disaster risk managers. This will deliver a flexible, user-configurable modelling tool to support socioeconomic flood risk assessment in Aotearoa. 

Objectives of research aim 2:

  • Support the development of more nationally-consistent decisions about land use, infrastructure, urban and rural development, nationwide disaster risk reduction and adaptation to flooding, reducing future liability issues.
  • Develop models and tools that support risk-informed decision-making on present-day and future mitigation actions for flood prone communities.
  • Deliver consistent New Zealand-wide information about land use, building and infrastructure risk to flood impacts.

Research aim 3: Societal vulnerability to cascading events

Led by Paula Blackett, NIWA

This part of the programme aims to develop useful, useable, scalable, and transferable sets of knowledge, processes and practices for understanding flood risks in a way that accounts for cascading impacts and complexity. 

Objectives of research aim 3:

  • Understand the social dimensions of flooding.
  • Use case studies and a systems-mapping approach to study how flooding affects hapū and communities, directly and indirectly.
  • Explore how cascading events (multiple large flooding events or combinations of flooding with other exacerbating factors) can affect tolerance to flooding, especially under climate change.

Research aim 4: Reducing flood risk and adapting to change

Led by Iain White and Silvia Serrao-Neumann, Waikato University; contact Belinda Sleight to find out more/register your interest

By bringing together river managers, iwi, government agencies, financial institutions and stakeholders, the researchers will ensure that the programme outputs are fit-for-purpose (useable, useful and used), explore adaptation options under changing climate conditions, and design new ways to make decisions, taking into account climate and socio-economic projections.This will allow organisations to develop policies, processes, and funding mechanisms to support a fair and transparent transition to a more flood-resilient country.

Objectives of research aim 4:

  • Bring together stakeholders to co-produce knowledge, engage with public and private sectors and develop policy and best practice guidance.
  • Explore how to use flood mapping to reduce the vulnerability of current and future developments to flooding.
  • Investigate how housing market signals may be used to enhance resilience to flooding.

Working together

There are many partners contributing to this research programme. The research is funded through the Ministry for Business, Innovation and Employment’s Endeavour Fund.


  • NIWA
  • Manaaki Whenua Landcare Research
  • University of Waikato
  • University of Canterbury 
  • University of Auckland 
  • University of Bristol (UK) 
  • University of Saskatchewan (Canada)
  • Deliberate
  • Weather Radar New Zealand
  • Neo Leaf Global Ltd
  • WSP
  • Tonkin & Taylor

Central and local government: We’re working with a variety of central and local government organisations including:

  • Ministry for the Environment
  • Land Information New Zealand (LINZ)
  • Department of Internal Affairs
  • Auckland Council
  • Greater Wellington Regional Council 
  • Otago Regional Council

Industry: We’re also working with a number of industry organisations and businesses, including the banking and insurance sectors.

Project updates

October 2021: First Science-Practice Roadshow a success

Collaboration with users of flooding information (models and maps) is essential if our research programme's outputs are to be useful, usable and used. The programme includes a series of science-practice roadshows to facilitate two-way information sharing between researchers and practitioners - including local and central government, Māori, land owners and community members.

Our first roadshow in late October was held online due Covid-19 restrictions on travel and meeting size. The morning session, attended by 50 people, introduced the project and gave an update on progress. A PDF of the Powerpoint slides is available here and a summary of the roadshow here. In the afternoon, a smaller group of researchers and stakeholders, mostly from central government, discussed the project and how it can best fulfil their data and information needs. 

We are planning two roadshows a year over the next four years. Topics covered will change as the programme evolves, but all will be focused on developing new tools that improve Aotearoa New Zealand's resilience to floods. We look forward to interacting with a wide range of interested people over the project's duration and beyond.

May 2021: Partnering with Auckland City to select sites for investigation

A visit to Auckland Council to identify locations for flood resilience case studies also provided an opportunity to understand the regional context and identify ways to work together. Engaging early with professionals who will use the maps and models that result from our research will make these tools more useful and useable in practice. 

Auckland faces a difficult balance between housing intensification and managing flooding risk. Future rainfall events are likely to increase in frequency and intensity so cities will need to find ways of adapting to these changing conditions while also accommodating future population growth.


Hydrodynamics Scientist

The name of this programme, “Mā te haumaru ō nga puna wai ō Rākaihautū ka ora mo ake tonu” acknowledges an ancestor of Wairewa Rūnanga, who are partners in the research.

It translates to “By keeping the water of Rākaihautū safe the water will survive eternally”. Rākaihautū was an ancestor who was said to traverse the South Island, digging and naming lakes as he travelled.

You’ll also see us use a shortened version of this name: “Mā te haumaru ō te wai”, which means “By keeping the water safe”.