Erosion and sediment risk maps
Sediment is the biggest water quality issue in Northland, and erosion is the key source of sediment.
Northland Regional Council has created erosion and sediment risk maps to help you identify where erosion is likely to occur and how likely sediment is to reach waterways.
What to use the maps for
The maps will be useful for managing erosion, farm plans, preparing consent applications, infrastructure planning, and for landowners who want to manage sediment and conserve soil. However, they do not provide a geotechnical assessment of land suitability for subdivision or built development, nor do they quantify the likelihood of erosion, landslides or slips in the future.
There are no rules associated with the maps, but they provide extra layers of information to help with better management of land and water. If any rules were proposed, they would go through a consultation process before being applied.
How the maps are created
The maps are based on a predictive model created using a range of information, including LiDAR (remote sensing technology that uses lasers to create 3D maps), soil and geology type, slope and climate data. The model and maps identify the underlying geological risk and sediment transport risk. They do not consider the influence of land use and land cover on erosion risk.
For more detail, read our background report and user guide. The background report describes the model that generates the map layers, including the data and how it is applied to predict erosion and sediment transport risk.
The user guide provides detail on erosion risk and how Northland landscapes behave.
What the maps show
The maps show where erosion is most likely to occur – and how likely sediment is to reach waterways.
They categorise risk into five colour-coded classes, from low risk (1 = green) to high risk (5 = red/orange).
You can view the maps at property scale or sub-catchment scale:
- Property scale offers a high resolution five-by-five metre view.
- Sub-catchment scale view shows overall risk for small watersheds (at minimum scale of two hectares) across the region.
How to view the maps
You can view the erosion and sediment risk maps online: