Extreme weather science response

Contracting organisation: NIWA

Funding: $830,000

Start and end dates: 27/2/2023 to 30/6/2024

Statement from NIWA

Cyclone Gabrielle first hit New Zealand on 12 February 2023. The impact will be felt for years. “Surge funding” for immediate needs was allocated so that flooded areas, sediment deposits and stop-bank breaches could be accurately located. 

The NIWA hydrodynamics team joined forces with the University of Canterbury and Christchurch Helicopters Limited. They mounted a LiDAR instrument (Light Detection and Ranging – a way of rapidly capturing topographic data to build a 3D map) on a helicopter, and used it to locate and document stop-bank breaches for the main Hawke’s Bay and Tairāwhiti rivers, and to identify the major flooded areas and sediment deposits. Most of the funds were needed for this urgent data collection. The team also combined data on the extent of flooding from SAR (Synthetic Aperture Radar) and satellites. Analysis of the gathered information is ongoing, and ArcGIS software is being used to make data accessible and to help in future assessments of changes in river geomorphology due to the flooding. 

NIWA also undertook an on-the-ground field survey of flood levels and stop bank breaches at locations stipulated by Hawke’s Bay Regional Council. They surveyed the depths, extent and bank breaches for flooding from the Tūtaekurī, Ngaruroro and Esk rivers. The data they collected will be used for calibrating hydrodynamic models and ground-truthing the LiDAR surveys. A staff member from Environment Canterbury assisted with this survey. 

The air quality team deployed mobile portable monitoring equipment to support regulatory authorities in the Hawkes Bay and Tairāwhiti regions from April to September 2023.  Analysis includes airborne particulates PM10  and respirable crystalline silica, and air quality impacts of the vast quantities of alluvial soil deposited, to inform public health decisions.

In addition to the work listed, NIWA continues to redirect existing projects to address needs arising from recent extreme weather events.

Contracting organisation: GNS Science

Funding: $1,695,000

Start-end dates: 27/2/2023 to 30/6/2024

Statement from GNS Science

GNS Science is responsible, through the Civil Defence Emergency Management Act and Plan, for providing science advice to responding agencies to support readiness for, response to and recovery from natural hazard events. The North Island Extreme Weather Events in January to February 2023 severely impacted multiple regions. GNS has been undertaking rapid science activities before, during and after the events and supplying timely advice to those agencies.

Before the events occurred, GNS was providing forecasts of landslide probabilities and impacts (on residential housing, state highways and railways) to NEMA using NIWA rainfall forecasts, delivered via RiskScapeTM modelling. Immediately after the events, our teams undertook rapid assessments of landslide damage from Northland to Wairarapa and provided near real-time information to emergency management and infrastructure providers. We hindcasted the landslide risk models using MetService actual rainfall data to target areas for rapid reconnaissance. GNS provided advice using a response framework based on the Co-ordinated Incident Management System.

As the regions transition into recovery, we are providing advice on the contamination of drinking water boreholes (in collaboration with ESR) and stability of landslide dams and landslide impacted areas to local authorities. We are mapping (with our University of Canterbury, Auckland University and Manaaki Whenua partners) landslides using remotely sensed data and making the maps available to inform decision making. Through the Resilience to Nature’s Challenges National Science Challenge, hosted by GNS, rapid science is being co-ordinated across the sector to support national and regional recovery. This includes developing summaries of key lessons for different stages of recovery management and assessing the impact of the extreme weather on coastal areas (the latter work undertaken by University of Auckland). With NIWA, we are co-leading the accelerated development of a RiskScape user interface to enable agencies and researchers access to standardised and regularly updated risk models and information. With Manaaki Whenua Landcare Research and NIWA, we are rapidly developing a data portal for sharing science information related to the response.

Contracting organisation: Manaaki Whenua Landcare Research

Funding: $200,000

Start-end dates: 27/2/2023 to 30/6/2024

Statement from Manaaki Whenua Landcare Research

Manaaki Whenua are providing a rapid assessment of landsliding in response to cyclone Gabrielle. Manaaki Whenua processed Sentinel-2 satellite imagery, pre and post cyclone Gabrielle, to assess the extent of land damage. Visual analysis showed that severe landsliding occurred in Gisborne, Hawkes Bay, and northern Wairarapa. For a strip of satellite imagery covering the severe landsliding areas, a map of landslide density was made. The summary shows severe landsliding in several zones along the east coast of the North Island (see Table). The mass of soil eroded was estimated as well as the cost. Of the 115 million tonnes of soil estimated to be eroded by landslides, approximately half would have entered waterways, and approximately 30% of that would have been deposited on floodplains. 

• Northern Hawke’s Bay coastal hill country – 4,500 square kilometres had 54.2 million tonnes of soil eroded at a cost of $271 million.
• Southern Hawke’s Bay and Northern Wairarapa coastal hill country – 4,392 square kilometres had 35.5 million tonnes of soil eroded at a cost of $177 million.
• Gisborne coastal hill country – 2,229 square kilometres had 13.5 million tonnes of soil eroded at a cost of $67 dillion.
• Ngatapa and upper Wairoa catchment hill country – 2,241 square kilometres had 12.1 million tonnes of soil eroded at a cost of $67 million.

 Further work will focus on finer resolution erosion zones mapping to assist in defining impacts and recovery options. We are working closely with MfE & MPI and plan to investigate how effective tree cover has been in minimising landsliding. To do this we plan to update landcover information in the affected region, as the LCDB (2018), is outdated and we need forest cover just prior to the cyclone so we can calculate accurate summary statistics. Soil quality contamination and limitations of use. Provision of data and analytics to assist regional council interpretation of recovery priorities. Providing advice and assisting iwi/hapu to access data and information that we hold. We are also investigating options to enable faster response in providing impact analytics at the time of an extreme event to enhance and compliment the early response information provided by NIWA and GNS through NEMA. We expect to continue to work with HBRC, MPI, DOC, MfE and LINZ to ensure data provision, analytics and interpretation to assist in response and preparing for recovery.

Contracting organisation: University of Auckland

Funding: $250,000

Start-end dates: 1/4/2023 to 31/12/2023

Statement from University of Auckland

This project will combine data and lessons learned to provide an evidence-base to support critical infrastructure recovery decisions following the North Island extreme weather events.

The first part of this project will focus on the impact of the events on critical infrastructure across the North Island including networks such as transportation, energy, communications and water. This will include the damage locations, damage characteristics and the reinstatement times where applicable. As infrastructure supports the wellbeing and function of communities and businesses, an important aspect also considered is the level of service provided by each infrastructure to those across the affected regions. Alongside the critical infrastructure networks themselves, the services that these networks support need to be understood, including impact on financial services and logistics networks. A true picture of all these aspects requires a view across all critical infrastructure given the interconnected nature of these networks. This will be combined to develop an information base representing how critical infrastructure and the services they support performed across all affected regions and how level of service varied with time following these events.

The second part of the project will look to other large scale natural hazard events that have occurred internationally and how the recovery of critical infrastructure networks in the affected regions was managed and supported. This will include a meta-analysis of disaster recovery reviews from academic and grey literature. These will be reviewed to identify key lessons and learnings that can further support recovery decisions and processes. This will be complemented by a summation of best practice principles for evaluating infrastructure investment decisions from a resilience perspective to support recovery decision-making that is responsive to community needs and changing hazard landscapes.

As critical infrastructure supports all aspects of modern life, a robust understanding of performance and implications of damage is needed to inform current and future decision making. Infrastructure is complex and networks rely on each other to function through dependencies, such as a water supply pump stations’ and fibre-communication networks’ reliance on electricity to function. Critical infrastructure is also managed by multiple agencies across multiple regions, each with varying priorities and levels of cooperation. The research team involved in this project is well placed to work with and across these agencies to provide an overarching representation of these effects and support coordinated and complex recovery efforts.

This project will be carried out through to the end of 2023 in stages. The project will be structured to be adaptive and able to pivot to meet priorities. As recovery entities evolve and identify their priorities the research team will look to anticipate needs and feed out information to inform this. Throughout the project information will be made available to entities from community through to the national level. At the end of the project a finalised information base of critical infrastructure performance will be released. Formal reporting related to both parts of the project will also be released in stages (through targeted bulletins) and combined into a single report at the culmination of the project.

This project will be delivered by a large multi-disciplinary, multi-institutional team that represents the leading researchers at the intersection of natural hazards and the built environment in Aotearoa New Zealand. Team members have led and delivered similar research following significant natural hazard events. Both experienced and emerging researchers will be involved, developing the capacity to respond to research needs for future events.

Contracting organisation: GNS Science, host of Resilience to Nature’s Challenges

Funding: $84,863

Start-end dates: 10/4/2023 to 30/6/2024

Statement from Resilience to Nature’s Challenges

Cyclone Gabrielle generated massive swells which impacted the east coast of the North Island. When combined with storm surge driven by the extremely low atmospheric pressure and strong winds these waves caused notable erosion along the coast. Many east coast communities have developed on low-lying coastal barriers, which are geologically young landforms comprised of unconsolidated sands. These barriers are often fronted by a series of sand dunes which provide a natural buffer between the beach and the land behind. In places the dunes have been artificially compromised by land development practices and vegetation changes, reducing their protective capacity. Several reports following Gabrielle show widespread erosion of the foredune, the most seaward sand dune within the system. In places, the foredune resembled a 1-3 m high “sand cliff” as waves eroded the dune face. Likewise, observations suggest that beaches fronting eroded dunes have also lowered, increasing the susceptibility of the beach to further erosion. Evidence from past storms shows similar behaviour, and post-storm surveys have shown that beach and dune recovery from severe coastal erosion events can take decades. However, the recovery of beaches is uncertain given accelerating rates of sea level rise and potential for further erosion over winter when the coast is exposed to stormier conditions.

Several coastal communities, have seen the coast erode back into council reserves and encroach on private property. Immediate responses to the storm have included demands for protective measures, such as seawalls, and heightened awareness of planning strategies such as hazard setback zones and managed retreat. Short-term responses to Gabrielle and long-term planning decisions require a robust understanding of the Gabrielle’s erosional impact and needs to place those impacts in the context of decadal-scale coastal behaviour.

This project will leverage existing and ongoing work undertaken by the Resilience to Nature’s Challenges (RNC2) National Science Challenge. The ‘New Zealand's Changing Coastline’ team will build upon their national scale coastal mapping programme to provide high-quality, timely and open data to understand the post-cyclone behaviour of the coast. Collectively these data are required to underpin discussions about medium and long-term planning and adaptation along the coast.

In order to achieve this aim, the project team will use a combination of field surveys to collect high-precision data on the state of the beaches, along with satellite data to map coastal change around most of the North Island’s east coast. Field surveys will precisely measure the topography of beaches, providing an understanding of beach change at ~10 highly-impacted beaches. In order to understand the impacts of Gabrielle across a broad spatial scale satellite imagery will be used to map erosion. Over the past three years the RNC2 New Zealand's Changing Coastline project has been mapping coastal change around Aotearoa over the last 70-80 years. Using historic aerial photographs and modern satellite imagery, the RNC2 team has generated times series of shoreline positions around the country. Councils use these types of data to support planning along the coast, including developing coastal setbacks. These planning tools typically account for the rates of coastal erosion over both long and short-term and project them into the future using various sea level rise projections.

The proposed project will extend existing shoreline records, which are generally sparsely sampled through time, to include the impact of Gabrielle along with the ongoing changes in the 12 months following the storm. By integrating these new data with the multi-decadal RNC2 records it will be possible to place storm impacts into the context of several decades of coastal change and provide the foundation for on-going coastal change monitoring to inform decision making within existing and new planning tools.

Contracting organisation: NIWA

Funding: $500,000

Start-end dates: 3/4/2023 to 29/9/2023

Statement from NIWA

Cyclone Gabrielle caused loss of life and significant damage to buildings, infrastructure and primary production in the regions of Hawkes Bay and Tairāwhiti. Sustainable long-term recovery of impacted communities and sectors needs to be informed by a sound understanding of present and future risk from multiple natural hazards.

This project will accelerate a multi-hazard risk model and information sharing platform, RiskScape, for Cyclone Gabrielle recovery agencies and researchers. The RiskScape Platform will host a customised multi-hazard risk modelling micro-site and information dashboard for agencies tasked with short and long-term recovery decisions for individuals, communities and sectors in Hawkes Bay and Tairāwhiti. 

Multi-hazard risk model operations enable decision makers to investigate present and future community or sector risk to different natural hazard impacts under future redevelopment and growth scenarios, climate change scenarios, and land use planning intervention options such as avoid, mitigate and adapt. Modelled analyses on costs and benefits of interventions will further provide a transparant evidence base for decision making on community and sector recovery futures.

Our multi-agency implementation team consists of science and technology leaders in multi-hazard risk assessment from NIWA, GNS Science, Catalyst IT, University of Auckland, University of Canterbury and Market Economics. We expect to deliver within 3 months the RiskScape Platform for cloud-based multi-hazard risk modelling and information sharing platform for Cyclone Gabrielle recovery agencies. In 6 months, a RiskScape Platform hosted micro-site will be delivered for recovery agencies to investigate the impacts and cost-benefits of different development and recovery futures and land use planning interventions for Cyclone Gabrielle impacted communities and sectors.

Contracting organisation: NIWA

Funding: $550,000

Start-end dates: 1/5/2023 – 31/12/2023

Statement from NIWA

Cyclone Gabrielle caused widespread flooding over much of the North Island of Aotearoa / New Zealand. The flood impacts were greatest in Hawkes Bay and Tairāwhiti regions, including loss of life and significant damage to buildings, land, infrastructure and primary production. In addition to the flooding, landslides generated huge amounts of sediment that have significantly altered the landscape in many areas, depositing 1-2 metres deep of sediment over several locations including the Esk, Dartmoor and Tangoio Valleys. Initial estimates suggest more than 5.8 million cubic metres of sediment has been deposited in the Esk Valley alone. Even more of this landslide sediment still remains in the upper catchments and will continue to affect the rivers and their geomorphology for the decades to come. The amount of rain that fell during this event was a game changer. It exceeded the expected maximum rainfall amounts in many locations causing floods that overtopped the stopbanks in over thirty locations along the Tūtaekuri and Ngaruroro Rivers alone. The flood significantly exceeded the design specifications causing erosion on the outside edges of the stopbanks. Attribution theory suggests that climate change may have contributed 20-30% to the rainfall intensity in this event.

It is vitally important to understand what this event tells us about the likelihood of a similar event happening again in the near future, especially within a changing climate. Changes to the river beds due to the amount of sediment coming down the system will have altered the flood hazard in these rivers and will continue to do so for decades to come as the sediment makes its way down to the sea. This project will undertake an analysis of the Cyclone Gabrielle flooding and use that information to model what future extreme flooding might look like in the Hawkes Bay and Tairāwhiti regions. It will look at how the sediment load in the rivers may have altered the effectiveness of the stopbanks and what might happen in the case of further stopbank breaches. This information will enable the district and regional councils, iwi/hapū and local communities to make informed decisions about their futures and to protect themselves in the event of flooding in the coming winter rainy season. This is urgent work because it will assist the district and regional councils respond as quickly as possible: to provide certainty to their residents, and inform emergency management and rebuild, repair or retreat.

We are working closely with the local councils (GDC and HBRC) to assess what the priority locations are, and to leverage off previous work. We are bringing together the expertise of NIWA, WSP and the Universities of Auckland and Canterbury, and will liaise with iwi/hapū, utilities providers, Civil Defence and Emergency Management users and central government agencies, as well as councils. In addition to the flood assessments, we will work to identify the next steps in ensuring Hawkes Bay and Tairāwhiti regions are protected from future flooding and can build back with increased resiliency.

Contracting organisation: Auckland UniServices Ltd

Funding: $450,000

Start-end dates: 23/5/2023 – 31/1/2024

Statement from Auckland UniServices Ltd

Aotearoa New Zealand (NZ) is at a critical time in terms of recovering from the COVID-19 pandemic and now responding to the crises created by extreme weather events. These emergencies have immediate and long-term consequences for the health and safety of individuals, families and communities. Young people (rangatahi) may be particularly vulnerable to the risks associated with extreme weather events, with normal developmental processes at this life stage influencing how they are able to cope with stress and uncertainty. During an emergency, rangatahi may also feel as though they have little control of what is happening around them.

Growing Up in New Zealand (GUiNZ) is NZ’s largest and most diverse longitudinal study, following over 6,000 children and their families since before they were born. The GUiNZ cohort is currently aged 13-14 years, with many living in the areas most severely affected by the extreme weather events including Te Taitokerau/Northland, Te Matau-a-Maui/Hawkes Bay, and Te Tairawhiti/Gisborne and the East Coast. Approximately one-third of the cohort live in Tāmaki Makaurau/Auckland, with the majority living in areas impacted by January flooding and Cyclone Gabrielle. Strong representation of rangatahi Māori and Pacific young people in GUiNZ empowers Government to uphold its responsibilities to Te Tiriti o Waitangi and ensures that commitments to equity and child and youth rights are being met.

GUiNZ provides an important opportunity for rangatahi experiences of the extreme weather events to be understood by Government and included in ongoing recovery work and future planning. For example, the timing of these events at the start of the 2023 school year will have disrupted their educational experience, which for most of the GUiNZ cohort included their transition into secondary school. Damage to local infrastructure and housing displacement will have impacted social connectedness and limited access to health and social services, all of which are critical to ensuring that young people are supported during a crisis. Early adolescence is a critical period in the lifecourse, marking the transition from childhood into adulthood, therefore major disruptions to wellbeing now can change future health and developmental trajectories in significant ways.

The aim of this project is to understand how the extreme weather events have impacted the wellbeing of rangatahi. The project will include a questionnaire-based survey of GUiNZ participants living in the areas that were most severely impacted by the extreme weather events. The questionnaires will be developed to capture a broad range of wellbeing domains, including but not limited to: physical and mental health, relationships with family and friends, neighbourhood safety, school engagement, as well as household measures such as access to financial supports/government benefits, food insecurity, housing and displacement, and transportation issues. Identification and prioritisation of the wellbeing measures captured in this study will be done in collaboration with government policy-partners, academic experts and stakeholder communities.

Data collection will begin in mid-2023, with online and in-person interviews available. Initial findings will be shared with stakeholders in Dec 2023/Jan 2024 using a mix of online reporting, stakeholder meetings and a selection of policy briefs. The study will be conducted by the GUiNZ team, who are experienced in undertaking rapid data collection with the cohort, including under extraordinary circumstances. For example, the team successfully completed a survey of the cohort in May 2020 during the early stages of the Governments Covid-19 elimination strategy, with a larger data collection wave undertaken in late 2021/early 2022 during the Delta and Omicron variant outbreaks. The data will be analysed by experienced researchers and data analysts in accordance with the GUiNZ data access policy. The dataset will be made available for research via our existing GUiNZ data access process in early 2024.

Contracting organisation: GNS Science

Funding: $250,000

Start and end dates: 8/5/2023 - 30/6/2024

Statement from GNS Science

In February 2023, MBIE reallocated $10.8 million for urgent science and data collection as part of the ongoing response to extreme weather events in the North Island. A number of individual projects have been initiated involving a range of science disciplines and agencies, working across different parts of the severely impacts areas, to collect perishable data and inform decision making in the locally-led recovery. Notably, many affected regions have resources that are economically or culturally significant to Māori communities, and a portion of funding has been allocated to enable Māori communities to access science services that support hapū and iwi decision-making. All SSIF projects have been identified through a collective of Chief Science Advisors working across local and central government, with input from an expert advisory panel to prioritise science that is the most urgent and likely to have the greatest impact in supporting disaster recovery. The diversity of projects and their potential interdependencies, the multiple participants, and the critical need to link the work locally and to national audiences all necessitate a mechanism to enable effective connection, coordination and communication of the collective work of the Extreme Weather SSIF Platform. This will require:

• mechanisms to connect projects with each other in the Extreme Weather SSIF Platform
• mechanisms to connect Platform projects with other relevant ‘external’ projects (for example, Endeavour, Resilience NSC, Deep South NSC Sustainable Seas NSC, BioHeritage NSC, CoREs etc.)
• mechanisms to connect Platform project activities and research progress with key users and partners in multiple locations
• mechanisms to coordinate the data collection and engagement activities of each Platform project (to minimise disruption to users and partners that may need to interact with multiple Platform projects (in addition to their recovery labour)
• mechanisms to communicate research findings in efficient and flexible ways across the range of users and partners in different regions
• leveraging of existing science, networks and capacity.

Independently facilitated coordination and communication between each Platform project and with users will:

• raise awareness among the wide range of potential users of the broad portfolio of research under the EW Platform, and related activity (e.g. through aligned Endeavour, NSC and other SSIF funded projects)
• enable individual projects to better deliver outcomes to key users through clearer pathways to connect and engage
• create opportunities to leverage data collection and use among projects
• create opportunities for research teams and users to explore follow-on science, aligned to user work programmes (for example, Council environmental managers).