Erosion-Prone Land
Land identified as susceptible to erosion from wind, water, or other natural processes, potentially affecting the stability and usability of a property.
What is a Erosion-Prone Land?
Erosion-prone land is mapped by regional and district councils in their planning documents. It includes land susceptible to various types of erosion: sheet erosion (topsoil removal by water or wind), gully erosion (concentrated water flow cutting channels), tunnel erosion (subsurface water creating underground channels), and streambank erosion (waterways undercutting their banks).
In New Zealand, erosion-prone land is widespread, particularly in areas with soft rock geology, steep terrain, high rainfall, or deforested hillsides. The East Cape, Wairarapa, Manawatu, and parts of Northland are particularly affected. Urban properties near streams, on hillsides, or on exposed coastal sites can also be erosion-prone.
Councils may impose restrictions on land use and development on erosion-prone land. This can include requirements for erosion and sediment control plans, vegetation maintenance, setbacks from waterways, and limitations on earthworks.
Why It Matters for Due Diligence
Erosion can progressively reduce the usable area of your property, undermine foundations, damage retaining walls, and create safety hazards. Land lost to erosion is generally unrecoverable, and the costs of erosion protection measures can be significant.
Check the LIM report and council planning maps for erosion-prone land overlays. If the property is identified as erosion-prone, understand what restrictions apply and what ongoing management may be required. Look for physical signs of erosion: exposed roots, undercut banks, sediment deposits, and gullies forming on slopes.
How to Check
The LIM report will flag erosion-prone land classifications. Regional council hazard maps and district plan overlays identify erosion-susceptible areas. For properties near waterways, check whether the council requires setbacks or riparian planting. A geotechnical engineer or erosion specialist can assess specific risk and recommend management measures.
Frequently Asked Questions
Can I build on erosion-prone land?
Possibly, but you may face additional requirements. Council may require a geotechnical assessment, an erosion and sediment control plan, specific foundation designs, or setbacks from erosion-prone features. Building costs will likely be higher due to these requirements.
Is erosion damage covered by insurance?
Generally, gradual erosion is not covered by standard home insurance. Sudden erosion caused by a storm or earthquake may be covered. EQC covers certain types of natural disaster-related land damage up to $300,000. However, ongoing, progressive erosion is typically considered a maintenance issue and is excluded from cover.
Related Terms
Coastal Erosion
GlossaryThe gradual loss of land along the coastline caused by wave action, tidal currents, weathering, and rising sea levels.
Land Instability
GlossaryThe risk of ground movement including landslides, slope failure, subsidence, and land slippage that can damage buildings and infrastructure.
LIM Report
GlossaryA Land Information Memorandum — an official council report summarising everything the council knows about a property.
Flood Zone
GlossaryAn area identified by the local council or regional authority as being at risk of flooding, based on historical data and modelling.
Resource Consent
GlossaryPermission from the local council to carry out an activity that affects the environment, required under the Resource Management Act 1991.
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