On October 30, 2025, Earth Sciences New Zealand released the country’s first-ever national flood hazard viewer—an interactive tool revealing that over 750,000 New Zealanders currently live in areas at risk from major flooding, with $235 billion in buildings exposed to one-in-100-year flood events.¹

This groundbreaking research comes just two weeks after the October 17, 2025 implementation of mandatory flood risk disclosure on LIM reports, providing homeowners with unprecedented access to nationwide flood data.

Access the National Flood Hazard Viewer

View the official Earth Sciences NZ Flood Hazard Viewer →

This free, publicly accessible tool allows you to:

• Check your property’s flood risk from 1-in-100 year rainfall events
• View projected water depths under current climate conditions
• See how flood risk changes with 1°C, 2°C, and 3°C of warming
• Compare your area’s risk to other regions nationwide

Key Findings from the 5-Year Research Programme

The research, led by Dr Emily Lane (Principal Hazards Scientist) and conducted over five years, applied consistent flood modeling across 256 floodplains nationwide.²

Population Exposure

Currently, 750,000+ New Zealanders (approximately 15% of the population) live in flood-prone areas vulnerable to one-in-100-year rainfall events. With 3°C of additional warming, this figure could rise to over 900,000 people.³

Property and Infrastructure at Risk

The research quantified New Zealand’s total flood exposure:

• $235 billion in building assets currently at risk (rising to $288 billion with warming)
• 26,800 km of roads exposed to major flooding
• 14,100 km of stormwater pipelines in flood zones
• 21% of national electricity grid sites in at-risk areas⁴

Regional Variations

Flood exposure varies dramatically across New Zealand’s regions:

Region	% of Population Exposed (Current)	Notes
West Coast	34%	Highest exposure nationwide
Hawke’s Bay	22% (rising to 31% with +1°C)	Most dramatic increase with warming
Taranaki	8%	Lowest regional exposure

Hawke’s Bay faces particularly concerning projections: exposure jumps from 22% to 31% with just 1°C of warming—a threshold that could be reached as early as 2029.⁵

How This Tool Complements Council Flood Maps

The national viewer fills a critical gap in New Zealand’s flood risk information landscape.

What the National Viewer Provides

• Consistent methodology across all 256 mapped floodplains
• Street-level resolution nationwide
• Future climate scenarios (+1°C, +2°C, +3°C warming)
• Coverage for areas without council flood maps

What Council Flood Maps Provide

• Property-level precision for specific addresses
• Local infrastructure details (stopbanks, drainage systems)
• Design specifications for building and development
• More detailed local modeling incorporating regional specifics

Important: The national viewer complements rather than replaces existing council flood assessments. For property-level decisions (buying, selling, building), you should still:

1. Check the national viewer for regional context
2. Obtain a LIM report from your local council
3. Consult council-specific flood maps for detailed information

See our complete guide to council flood viewers for links to all regional flood mapping tools.

Why Historical Floods No Longer Guide the Future

As Dr Emily Lane explains: “The building of our towns and flood defences have been shaped by historical floods that are no longer a reliable guide to the future.”⁶

The research addresses this by modeling future scenarios:

• Current climate baseline: Based on recent climate conditions
• +1°C warming scenario: Likely by 2029-2040
• +2°C warming scenario: Projected by 2050-2070
• +3°C warming scenario: End-of-century projection

This forward-looking approach helps homeowners, councils, and insurers understand how flood risk will evolve over the typical lifespan of a mortgage or building.

Impact on Property Values and Insurance

The national data reinforces findings from our property values impact analysis:

Property Market Effects

• High flood risk properties typically see 4-10% value reduction when risk is disclosed
• Medium risk properties may experience 2-6% price impact
• Time-to-sell increases 20-60% for high-risk properties⁷

Insurance Implications

Since late 2023, insurance premiums for properties flagged as high flood risk have risen $500-$5,000 per year, with some policies seeing doubled or tripled excess levels.⁸

With the national data now publicly accessible, insurers can more systematically assess flood risk across their portfolios, potentially leading to broader premium adjustments in 2026.

What Property Owners Should Do Now

If you own property in New Zealand:

1. Check the National Flood Hazard Viewer (5 minutes)

Visit the Earth Sciences NZ viewer and search for your property address. Note:

• Current flood depth in a 1-in-100 year event
• How this changes with warming scenarios
• Your region’s overall exposure level

2. Review Your Council’s Detailed Maps (15 minutes)

Cross-reference the national data with your local council flood viewer. Council maps provide property-level precision and local infrastructure details.

3. Request a LIM Report If Considering Sale/Purchase (1-2 weeks)

Since October 17, 2025, all LIM reports include standardized flood risk information. Typical costs:

• Standard LIM (10-day processing): $235-$280
• Urgent LIM (5-day processing): $450-$500⁹

See our complete LIM guide for details on interpreting your report.

4. Review Your Insurance Coverage (30 minutes)

Contact your insurer to:

• Confirm your flood coverage status
• Understand your excess levels for flood claims
• Discuss any premium changes expected in 2026
• Explore flood mitigation discounts if available

5. Consider Flood Mitigation (If High Risk)

For properties in high-risk zones, flood mitigation can:

• Reduce insurance premiums (10-30% in some cases)
• Minimize potential damage costs
• Potentially improve property values

Common mitigation measures range from $10,000 to $100,000+ depending on scope:

• Floor level raising ($40,000-$100,000+)
• Improved drainage systems ($5,000-$20,000)
• Sump pumps and backflow valves ($2,000-$8,000)
• Landscaping and grading ($10,000-$30,000)¹⁰

The Research Behind the Tool

This five-year programme represents New Zealand’s most comprehensive flood risk assessment to date.

Methodology

Researchers applied a consistent 1% AEP (Annual Exceedance Probability) rainfall model across 256 floodplains, accounting for:

• Current topography and drainage patterns
• Existing flood protection infrastructure
• Climate change rainfall projections
• Regional rainfall intensity variations

Why This Matters

As natural hazards researcher Ryan Paulik notes: “How we develop in and around floodplains is what’s going to be driving the potential losses in the future.”¹¹

This data enables:

• National-scale adaptation decisions based on evidence rather than assumptions
• Strategic prioritization of flood protection investments
• Informed development planning in high-growth areas
• Climate-aware infrastructure planning for long-term resilience

Looking Ahead: Climate Change and Adaptation

Dr Emily Lane’s team emphasizes the urgency: “We’ve been making those national-scale adaptation decisions in a vacuum. [This research] creates a risk of adapting in the wrong places first.”¹²

Key Implications

1. Immediate exposure is significant: 15% of New Zealanders already at risk
2. Rapid escalation with warming: Just 1°C increase pushes Hawke’s Bay from 22% to 31% exposure
3. Infrastructure vulnerability: 21% of grid sites exposed threatens energy resilience
4. Adaptation prioritization: Data enables evidence-based investment in flood protection

What Comes Next

The research programme continues to release additional data products:

• Refined regional modeling for specific catchments
• Coastal inundation mapping (separate from rainfall flooding)
• Integration with other hazard data (landslides, earthquakes)
• Regular updates as climate projections improve

Conclusion: Unprecedented Transparency in Flood Risk

The release of the national flood hazard viewer marks a watershed moment for New Zealand property owners. For the first time:

• Consistent nationwide data enables direct regional comparisons
• Future climate scenarios show how risk evolves over time
• Publicly accessible tools democratize flood risk information
• Evidence-based decisions replace reliance on historical flood records

Combined with the October 17, 2025 LIM disclosure requirements, New Zealand now has one of the world’s most transparent flood risk frameworks.

Take action today: Check your property on the national flood viewer and understand your risk before it affects your property value or insurance costs.

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Frequently Asked Questions (FAQ)

How do I access the national flood hazard viewer?

Visit the Earth Sciences NZ Flood Hazard Viewer and search for your property address. The tool is free and publicly accessible.

What does 1-in-100 year flood mean?

A 1-in-100 year flood (1% AEP) means there’s a 1% chance of this level of flooding occurring in any given year. It doesn’t mean it only happens once every 100 years - multiple 1-in-100 year floods can occur in quick succession.

Should I use the national viewer or my council’s flood map?

Use both. The national viewer provides consistent comparison across regions and future climate scenarios. Council maps offer property-level precision and local infrastructure details. For important decisions, always check both sources.

How many New Zealanders are at flood risk?

Currently, over 750,000 New Zealanders (15% of the population) live in areas at risk from 1-in-100 year floods. This could rise to 900,000+ with 3°C of additional warming.

Which region has the highest flood risk?

The West Coast has the highest exposure with 34% of residents in flood zones. Hawke’s Bay shows the most dramatic increase with warming, jumping from 22% to 31% exposure with just 1°C of temperature rise.

Will this affect my insurance premiums?

The national data enables insurers to better assess risk across their portfolios. This may lead to premium adjustments in 2026, particularly in high-risk areas that weren’t previously flagged.

How accurate is the national flood modeling?

The modeling uses consistent methodology across 256 floodplains and is based on 1% AEP rainfall scenarios. However, it’s designed for regional comparison rather than property-level precision. For specific property decisions, consult your council’s detailed flood maps and obtain a LIM report.

When was this research conducted?

The research was conducted over five years by Earth Sciences New Zealand, with the flood hazard viewer released on October 30, 2025.

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Sources and References

Footnotes

1. Earth Sciences New Zealand. (2025, October 30). Nationwide study reveals escalating flood risk. Retrieved from https://www.earthsciences.nz/news/nationwide-study-reveals-escalating-flood-risk ↩

2. RNZ. (2025, October 30). New national flood data reveals the areas most at risk - now and in future. Retrieved from https://www.rnz.co.nz/news/national/577238/new-national-flood-data-reveals-the-areas-most-at-risk-now-and-in-future ↩

3. Earth Sciences New Zealand. (2025). National flood hazard research programme - Population exposure analysis. ↩

4. Earth Sciences New Zealand. (2025). National flood hazard research programme - Infrastructure exposure analysis. ↩

5. RNZ. (2025, October 30). Regional flood exposure projections with climate warming scenarios. ↩

6. Earth Sciences New Zealand. (2025, October 30). Dr Emily Lane, quoted in nationwide flood risk announcement. ↩

7. Based on NZ and Australian market analysis of flood-affected property sales, 2020-2024. ↩

8. Insurance Council of New Zealand. (2024-2025). Flood risk premium adjustment data. ↩

9. Based on average LIM costs across major New Zealand councils, October 2025. ↩

10. Based on typical flood mitigation costs reported by NZ building and engineering professionals, 2024-2025. ↩

11. RNZ. (2025, October 30). Ryan Paulik, natural hazards researcher, quoted in flood risk coverage. ↩

12. Earth Sciences New Zealand. (2025, October 30). Dr Emily Lane, quoted in research announcement. ↩