Natural hazards

Photo of erosion of cliffs at One Tree Point.

Find out what natural hazards are listed for your property and how this affects what you can do on your property.

Natural hazards include:

  • acid sulphate soil
  • coastal erosion and flooding
  • river flooding
  • land instability
  • liquefaction
  • mining subsidence.

First use the hazard layer in our GIS Maps to find what natural hazards your property is at risk from. Then check our District Plan to see how these hazards affect how you can develop your land.

Changes have been proposed to the natural hazard chapter of the district plan. Find further information about this proposed plan change on this page:  

Plan Change 1: Natural Hazards

What hazards apply to my property?

  1. Open the Hazards map within GIS
  2. Image for the search icon within GIS Maps. Enter your address in the top left hand search box
  3. Image for the layers icon within GIS Maps. Click on 'layers' in the banner
  4. Select the hazard layers from the right-hand side bar to see if it applies to your property. 
  5. legend-icon.png Click on 'legend' in the banner to see what each coloured area / pattern means. 

District wide rules for hazard areas

The District Plan includes rules for development in flooding, mining subsidence and coastal hazard areas. These rules may require you to obtain a resource consent, in addition to meeting building consent requirements relating to natural hazards. 

District Plan

Natural hazards - Building consents

On 31 May 2023 Plan Change 1 - Natural Hazards was notified. The plan change proposes new rules to manage the risk to people and property associated with the following natural hazards:

  • river flooding
  • coastal erosion and flooding
  • land instability
  • mining subsidence.

Read further information about this proposed plan change:

Plan Change 1 - Natural Hazards

Types of natural hazards

Acid sulphate soil

Acid sulphate soils are naturally occurring.  They are caused by sulphate salts that were deposited in the land by the sea.

When sulphate soils are disturbed, they react with oxygen and create an acidic environment which can corrode buried infrastructure including concrete and steel.

The risks of acid sulphate soils are considered through the resource consent process and through building consents. 

You can read more information about the assessment of acid sulphate soils during the building consent process on the following page.

Natural hazards (Building Act 2004)

Areas that are known to have acid sulphate soil are shown on our GIS maps and in LIM reports.

You can read more about this phenomenon on the following page:

Acid sulphate soil planning policy

Coastal hazards

Erosion, landslips and sea water flooding are the dominant natural coastal hazards along the District's coastline.

Coastal erosion is either a long-term trend or a significant short-term shoreline fluctuation, especially on sand dune-backed coasts. 

Landslips are directly associated with coastal erosion where the geology is relatively weak and prone to slope failure.

Severe coastal storms or tsunamis produce waves which can temporarily flood low-lying coastal areas. The effects of climate change are likely to increase hazards in the coastal zone.

Coastal hazards mapping

The Northland Regional Council manage coastal hazard mapping for coastal flooding and coastal erosion. 

In April 2021, the Northland Regional Council released a new update to the coastal flooding and coastal erosion maps.   

Update to coastal hazard maps (nrc.govt.nz)

The Coastal Hazards mapping in the District Plan is proposed to be updated to reflect the Northland Regional Council information as part of the proposed Natural Hazards Plan Change.

Plan Change 1 - Natural Hazards

Coastal hazard reports

The Northland Regional Council holds the most recent reports relating to coastal hazards:

Coastal hazard assessment reports (nrc.govt.nz)

These coastal hazards reports have informed the mapping that is proposed to be included in the Natural Hazards plan change.

Coastal Management Strategy

In 2002 a Coastal Management Strategy was developed for the District.

Coastal Management Strategy

River flood mapping

Tropical storms and high rainfall intensities expose many areas to flooding. There are obvious floodway areas plus areas that are susceptible to ponding. 

River flood mapping is used in the assessment of applications for resource consent and / or building consent. 

River flood maps 

In November 2021, the Northland Regional Council released a new update to the Northland's region-wide river flood maps. 

Update to river flood maps (nrc.govt.nz)

The flood hazard mapping in the District Plan is proposed to be updated to reflect the Northland Regional Council information as part of the proposed Natural Hazards Plan Change. 

Plan Change 1 - Natural Hazards

River flood hazard reports

The Northland Regional Council holds the most recent reports relating to river flooding.

Region-wide river catchments analysis - technical reports (nrc.govt.nz)

These reports have informed the mapping that is proposed to be included in the Natural Hazards plan change.

Flood susceptible mapping report

The Flood Susceptibility Mapping Report 2001 prepared prior to the Northland Regional Flood mapping includes information in relation to mapped Flood Susceptible Areas. 

Flood Susceptible Areas are identified in our Hazard Map within GIS.  

Land instability

Geological characteristics and soil types in the District mean that some areas some areas should be developed carefully, and may require substantial works to avoid, remedy or mitigate land instability hazards. 

Inappropriate earthwork activities and / or the removal of vegetation also contribute to land instability. 

Land instability maps

Land instability has been mapped across the District and currently informs the subdivision consent and building consent processes.  

These maps are proposed to be incorporated into the District Plan as part of the proposed Natural Hazards plan change.

Plan Change 1 - Natural Hazards

Land instability reports

The following technical reports relate to the mapped instability hazards.  

Urban Land Stability Hazards for Te Kamo, Maunu, Onerahi, Otaika and Tikipunga(PDF, 386KB)

Urban Land Stability Hazards for Hikurangi, mid-Kensington, Whangarei City Centre and East Te Kamo(PDF, 836KB)

Urban Land Stability Hazards for Kensington, Morningside and Port(PDF, 203KB)

Coastal Slope Instability Hazards for Ōakura to Langs Beach(PDF, 549KB)

Landslide Susceptibility Technical Report 2020(PDF, 8MB)

Liquefaction

Liquefaction is a natural process where earthquake shaking increases water pressure in the ground in granular soils, resulting in temporary loss of soil bearing capacity.

Liquefaction commonly leads to buildings ‘sinking’ on their foundations during the shaking – in line with that experienced in the 2011 Canterbury earthquakes.

Tonkin & Taylor Ltd was engaged by us in April 2020 to undertake a liquefaction vulnerability assessment.

The work comprises risk identification and analysis of liquefaction hazard in accordance with the Ministry of Building, Innovation and Employment (MBIE) and the Ministry for the Environment (MfE) Planning and engineering guidance for potentially liquefaction-prone land (MBIE/MfE, 2017) to help inform decisions about future development of land and buildings.

Building Consent applications must include consideration of the liquefaction risk of the subject property as part of the site suitability report.

Liquefaction hazard mapping report(PDF, 27MB)

Mining hazards

Coal mining was formerly a major industry in Northland and major coalfields were located at Te Kamo and Hikurangi, both of which are now urbanised. 

Hazards such as subsidence, sink hole formation and unstable fill restrict development in these areas.

A geotechnical report is required for development withing areas of mining subsidence.

Mining subsidence maps

Mine subsidence maps for the District are incorporated into the District Plan and are used to identify current areas of risk from mining subsidence as part of the resource consent and building consent processes.

The mining subsidence maps for Hikurangi are proposed to be updated as part of the Natural Hazards plan change.

Plan Change 1 - Natural Hazards

Mining subsidence reports

The following technical reports relate to the mining subsidence maps.

Mine Subsidence Hazard - Hikurangi Area(PDF, 242KB)

Mine Subsidence Hazard - Te Kamo Area (2013)(PDF, 2MB)

Mine Subsidence Hazard - Te Kamo Area (2005)(PDF, 307KB)

Te Kamo Mine Zones Map (March 2005)(PDF, 1MB)

Additional information about natural hazards in New Zealand can be found on the Natural Hazards portal created by Toka Tū Ake EQC:

The Natural Hazards Portal – Toka Tū Ake EQC