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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
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.
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.
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:
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:
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:
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:
There are many partners contributing to this research programme. The research is funded through the Ministry for Business, Innovation and Employment’s Endeavour Fund.
Central and local government: We’re working with a variety of central and local government organisations including:
Industry: We’re also working with a number of industry organisations and businesses, including the banking and insurance sectors.
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.
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”.