Source: Porirua City Council
Porirua City is about to publish draft district-wide assessments that map where landslide and liquefaction geohazards are more likely to occur in Porirua. Flood hazard modelling is also being updated for five of our catchments.
The maps produced with the assessments will provide the most up-to-date information on these hazards for residents, as well as planners, engineers, developers, and owners and managers of critical infrastructure, so they can help our communities plan for the future.
Nicola Etheridge, General Manager Policy, Planning and Regulatory Services says these assessments will help Council and residents understand the risks we face from hazards.
“The way our city has developed over time has meant we have sometimes built in places that are susceptible to natural hazards. Mapping these hazards will help us plan better for the future, including how and where we build on and develop the land.
“Geohazard assessments identify areas of land that might be prone to these hazards, based on certain known factors. For example, a steeper slope will be more likely to slip under the same conditions than a shallower slope,” she says.
The draft maps will be shown on Land Information Memorandum (LIM) documents to inform current, prospective and future owners of the potential for landslides, liquefaction and flooding in an area. They will also be used in decision-making for the Council when identifying areas for development or for building Council assets like infrastructure. For liquefaction, the new maps will supplement the existing regional liquefaction maps that are already shown on LIMs.
LIMs will include a statement noting that these maps are currently in draft and are based on available data.
The draft landslide and liquefaction assessments and maps will be updated as needed, including when the peer review process is completed and when significant new data is available. They are being released in their draft state because the Local Government Official Information and Meetings Act (LGOIMA) requires councils to publish the information once it is known.
“Once finalised, we are looking to include these hazards in the District Plan, which directs how we change, develop and use our land and environment. This will include new maps and rules in the plan that will need to be followed when building in these areas.
“We are hoping to have a draft of the changes to the District Plan out for comment in the coming months and these maps will be used as part of the consultation process.
“Our District Plan is already best-practice by having a risk-based framework for managing a range of natural hazards – flooding, fault rupture, tsunami and coastal erosion and inundation. However, our understanding of landslides and liquefaction in Porirua wasn’t initially detailed enough to map these in the District Plan, so we’re now working to add those in,” says Nicola.
For more information about hazards in Porirua, visit our page Responding to natural hazards. The maps will be on our GIS page in the coming weeks.
