BETA — overland flow paths, 2024 LiDAR, data under review

New Zealand Overland Flow Paths.
Every stream. Every property.

A free public layer of sub-regulatory overland flow paths, built on 2024 LINZ LiDAR. The detail the National Flood Map doesn't resolve — for engineers, developers and councils screening sites.

Built by Andre Magdich CPEng — 15+ years stormwater and subdivision
LINZ 2024 LiDAR composite (L121859)
Aligned with TP108, SWCoP v4, NZS4404
The problem

Your council flow path layer doesn't cover your site.

Most New Zealand council flood maps are built on 2016 or older DEMs. Many don't model overland flow paths at all — only big rivers. The new National Flood Map stops at 256 floodplains and explicitly excludes property-level detail.

That's fine for public awareness. It isn't enough for early site screening or pre-purchase due diligence. FloodMap.nz publishes a consistent national overland flow path layer — every stream down to 0.4 hectares, derived from 2024 LiDAR, at property-level resolution. Free to view.

What you get

Three layers, every square metre of New Zealand.

Tier 3

Major overland flow paths

25 to 500 hectare catchments. Regional flood planning, district plan work, subdivision-scale overview.

Tier 4

Secondary flow paths

2 to 25 hectare catchments. Subdivision design, consent assessment, SWCoP compliance.

Tier 5

Fine flow paths

0.4 to 2 hectare catchments. Site-specific flood risk, FFL design, sub-regulatory detail.

Who it's for

An engineer-built reference layer, used by people who need it.

Engineers & Surveyors

Cross-check the council layer

Find the flow paths the council mapping missed when their LiDAR was older. Useful for site walks and rational-method sanity checks.

For engineers →
Developers

Screen sites before you settle

Check whether overland flow paths cross a property before you commit to formal due diligence. Free to view.

For developers →
Councils

A second reference layer

Nationwide overland flow paths your team can compare against existing council mapping. Methodology open.

For councils →
Planners & Architects

Early-stage screening

See where flow paths constrain building platforms before you finalise layouts or lodge an application.

Open the map →
Hazards & Civil Defence

Property-level flow visibility

Free public reference for pre-event briefings and public communications. Open methodology, documented limitations.

Read the methodology →
The general public

Search any NZ address

See where overland flow paths cross or pass close to a property. No login, no cost, no quota.

Open the map →
How we compare

FloodMap.nz vs the alternatives.

The government National Flood Map and council viewers are public awareness tools. FloodMap.nz is the property-level overland flow path overlay that complements them.

FloodMap.nz ESNZ National Viewer Council GIS MfE National Flood Map (2027)
Full NZ coverage (rolling out)Rolling outYesOne region eachYes
Property-level detailYesNoSometimesNot committed
2024 LiDARYesMixed, mostly pre-2023Usually 2016Varies
Overland flow paths (0.4ha+)YesNoRareNo
Free public accessYesYesYesYes
Open methodologyYesPartialVariesTBC
Methodology

Built the way a CPEng would defend it.

Every layer is derived from current LiDAR, processed with open methodology, and aligned with the standards councils use.

1 m
DEM resolution
0.4 ha
Smallest catchment
2024
LiDAR composite
Quarterly
Update cycle
TP108
Rainfall standard
SWCoP v4
Stormwater code

Read full methodology →

FAQ

Questions we get asked.

Isn't this the same as the Earth Sciences NZ flood viewer?

No. ESNZ's viewer is a public awareness tool covering 256 major floodplains at street level — explicitly not for property-level risk assessment. FloodMap.nz covers every stream down to 0.4ha catchment, at property-level resolution, on newer LiDAR. Different scale, different purpose.

Will the MfE National Flood Map (2027) replace FloodMap.nz?

No. MfE's 2027 product is an aggregator — it stitches together what each council already has. Where councils have detailed models, MfE will surface them; where they don't, MfE won't fill the gap. FloodMap.nz builds a consistent national model from the DEM up.

Is this data council-approved?

The methodology is aligned with TP108, SWCoP v4, and NZS4404. Individual councils make their own call on what data they accept for consent. The free layer is a screening reference, not a regulatory hazard map — for site-specific consent submissions, that's an engineering job done on commission.

What about coastal flooding?

The current published layer focuses on rainfall-driven overland flow. Coastal storm surge and sea-level rise are not modelled. For coastal hazard, we recommend the NIWA / Earth Sciences NZ Extreme Coastal Flood Maps.

How often is it updated?

The layer is reissued as new LINZ LiDAR survey blocks are published. Affected regions are reprocessed against the latest composite.

Can I download the data?

The free public map is view-only. Data exports and API access for engineers and councils are under development — register interest via the contact form.

Do you do site-specific flood assessments?

Yes — through SAE Ltd. Site-specific HEC-RAS 2D flood assessments (depth, velocity, hazard, before/after earthworks) are scoped per site as bespoke engineering. See /flood-report for what's typically covered, or get in touch.

Find out what's under your site.

Free to view. Search any NZ address. No login.