The art of mapping the edge

To protect New Zealand’s coastline, Toitū Te Whenua Land Information New Zealand (LINZ) has launched the 3D Coastal Mapping Programme. Over three years, this technically demanding initiative will capture elevation and seafloor data of up to 40% of New Zealand’s coastline. By supporting hazard modelling, infrastructure resilience and long-term planning, LINZ isn’t just mapping the coast – it’s mapping the country’s future.

New Zealand’s coastline is a dynamic frontier: wildly beautiful, economically vital and increasingly vulnerable. As rising seas, shifting landforms and intensifying storms reshape the nation’s shores, the stakes for communities, infrastructure and ecosystems grow higher. In response, Toitū Te Whenua Land Information New Zealand (LINZ) has launched a bold and technically demanding initiative: the 3D Coastal Mapping Programme. Over three years, LINZ and its partners will capture high-resolution elevation and seafloor data across up to 40% of New Zealand’s coastline.

This isn’t just a data collection exercise. It’s a complex, multi-year operation that bridges land and sea, and integrates diverse technologies. The effort navigates some of the most environmentally and logistically challenging terrain in the Southern Hemisphere – from highly turbid waters and steep topography to protected wildlife zones, all in unpredictable weather. The resulting detailed maps will support hazard modelling, infrastructure resilience and long-term planning.

Success factors

The success of the 3D Coastal Mapping Programme hinges on multiple factors. These include strategic collaborations with partners experienced in mapping complex geographies; flexible, multi-technology approaches to data collection; a strong focus on data quality and harmonization; and engaging with stakeholders throughout the process.

For example, NV5 Geospatial brings experience from remote projects in Alaska, Canada and the Caribbean – regions with similar terrain and environmental challenges. In mapping the South Island, the programme leverages a suite of complementary technologies – from aerial topobathymetric Lidar and imagery for seamless land‑to‑sea coverage, to multibeam acoustic bathymetry by boat to fill Lidar gaps in deeper or more turbid waters. This multi‑sensor approach ensures that even areas impacted by suspended sediment or dynamic seafloor movement are captured with high confidence.

To help facilitate efficient data acquisition and forecast conditions, NV5 works with hydrospatial services provider TCarta to obtain persistent satellite-derived bathymetry and water quality analytics. Then, NV5 can make real-time flight adjustments to accommodate weather, water clarity and prioritize data capture and processing in areas where LINZ’s stakeholders have a pressing need.

Collaboration tools

The programme also employs collaboration tools to speed up quality assurance (QA) and quality control (QC) of the acquired data. NV5 developed QAURA, an Esri StoryMap platform for managing and consolidating Lidar information collected in the field. This tool supports visualization of project status and generation of preliminary raster products within one week of acquisition, enabling rapid review and consultation among project partners.

Stakeholder engagement is another cornerstone of the programme. For example, NV5 has set up a WhatsApp group to keep LINZ up to date on plans and last-minute changes to flights. This enables LINZ to communicate with local councils, indigenous communities, airports and media outlets, promoting transparency around flight operations and ensuring understanding of how the data is being collected and can be used. Moreover, weekly meetings reinforce robust QA/QC processes and harmonize new datasets with existing ones.

Tackling challenging environments

Mapping New Zealand’s coastline is no small feat. The South Island, in particular, presents formidable challenges for aerial Lidar collection. Data acquisition is complicated by high turbidity zones, like those along Otago’s coastline, as well as sediment-laden waters and surf zones. There are areas of steep topography and rugged terrain, particularly on the West Coast, not to mention black and dark sand beaches. These conditions directly influence how well bathymetric Lidar can penetrate the water column and return usable data. Despite these challenges, analysis of the point clouds and derived surface models shows that bathymetric Lidar has generally performed well across the South Island project areas. In regions not heavily impacted by sediment input, the results have even exceeded those from other projects with similar shoreline characteristics.

Environmental variability is a constant factor, however. Together, the technical and environmental considerations highlight the delicate balance required for precision coastal mapping – one that blends advanced sensing technologies with an adaptive, environmentally sensitive approach. Above all, it is important to understand the coastal system as a living, moving environment. For instance, suspended sediment has produced unique data patterns not previously observed in other programmes, and dynamic seafloor changes – particularly near river outlets – have introduced temporal differences between missions. In another example, the team intentionally flew the Taiaroa Head albatross colony area at different times to avoid disturbing the birds. The temporal variation this introduced was later minimized in the final model through careful harmonization of overlapping datasets.

The technology itself has proven resilient. When conditions are good, the results are consistently strong: clean bottom returns, well‑defined intensity layers, and high‑fidelity point clouds that translate into robust digital surface models (DSMs). In more challenging areas – such as the world‑class surf zone at Dunedin – NV5 executed targeted infill missions to strengthen coverage. These infill flights have been largely successful thanks to ongoing dialogue with LINZ, whose local expertise has been essential for planning around surf zone features, sediment plumes and weather windows.

TCarta’s satellite services have also become an increasingly valuable asset, supporting mission planning and validating data coverage. These insights have already improved operational efficiency, and the team expects to expand their use even further in the future.

Mapping the future

In a world where coastlines are shifting faster than ever, mapping the edge isn’t optional – it’s essential. By embracing cutting-edge Lidar technology, collaborative partnerships and transparent practices, LINZ is setting a new standard for coastal mapping in complex environments. This initiative is more than a technical milestone – it’s a strategic investment in the future of New Zealand’s communities.

The 3D Coastal Mapping programme: the foundation for a resilient future

New Zealand’s coastline is home to approximately 65% of the country’s population and supports critical infrastructure that underpins the nation’s economy and way of life. As climate change accelerates, understanding how the shores are changing has never been more important. This is why Toitū Te Whenua Land Information New Zealand (LINZ) launched the 3D Coastal Mapping (3DCM) programme in 2023.

Purpose and scope

The 3DCM programme supports the creation of detailed maps of vulnerable and populated parts of the coastline and adjacent sea floor, which amounts to nearly 40% of the coast. Significant infrastructure corridors and regions at higher risk of coastal inundation will be mapped, covering nearly 10,000km². The data collected will address a critical gap in the understanding of coastal environments and will provide a baseline to monitor future changes from climate events and natural hazards. 

Running through to June 2027, the programme is using Lidar technology to capture detailed topographic and bathymetric data, creating seamless coverage from 200m inland extending out to 25m below the waterline. This zone represents the dynamic interface between land and sea – an area that is particularly vulnerable to climate impacts and has been historically challenging to map.

Benefits for Aotearoa New Zealand

The value of this programme extends across multiple sectors and communities. Local and central government agencies will use the data to enhance hazard and risk modelling, improving the understanding of flood zones, tsunami inundation areas and long-term climate adaptation needs. This supports more informed infrastructure planning, ensuring roads, railways, cultural assets (such as marae) and essential services are positioned to withstand future coastal challenges.

The aquaculture industry gains access to precise seabed mapping, enabling better site selection and environmental management. Maritime operators benefit from updated nautical charts that enhance navigation safety – a core component of LINZ’s hydrographic responsibilities. Environmental managers can use high-resolution seafloor data to map and protect marine habitats and biodiversity. Emergency services will be equipped with accurate elevation models to develop effective evacuation routes and response plans.

Collaborative approach and open data

The success of the 3DCM programme relies on strong partnerships and stakeholder engagement. Since January 2025, specialist firms Woolpert NZ Limited and NV5 Geospatial have been contracted to map across the North and South Islands respectively. LINZ is working closely with regional councils, whose existing topographic Lidar coverage complements the coastal focus, creating a comprehensive elevation dataset covering over 90% of the country. Where turbid waters prevent Lidar penetration, the gaps are filled using multibeam echosounder bathymetry.

In keeping with LINZ’s commitment to data accessibility, this data is openly available as a single dataset called ‘New Zealand Coastal LiDAR 1m DEM’ (https://data.linz.govt.nz/layer/122508-new-zealand-coastal-lidar-1m-dem/) through the LINZ Data Service and the Open Data Registry. This ensures that communities, researchers and developers can integrate this information into their planning and decision-making tools.

Looking forward

As climate change continues to reshape New Zealand’s coastline, the 3DCM programme represents LINZ’s commitment to building national resilience through knowledge and preparedness. By creating a living record of the coastline, the organization is empowering future generations with the information they need to protect communities, support sustainable development and preserve the coastal ecosystems that define Aotearoa New Zealand.