We are currently updating the modelling and information for these maps. More information, including how you can provide feedback, is below.
To find flood hazard information about a specific area, please view our GIS maps online: GWRC GIS flood Hazard Areas or KCDC GIS flood extents.
Flood hazard modelling
Flood hazard modelling involves the use of hydrological and hydraulic models to estimate the range of possible floods that could occur in a catchment and the hazards associated with these events. Flood hazard models produce a series of flood hazard maps and data for each scenario model.
The models are used by Greater Wellington for flood warning, floodplain management planning, asset management and advice during emergency responses. Greater Wellington shares the models with organisations such as Wellington Region Emergency Management Office (WREMO), territorial authorities and the public for emergency planning and management, district planning, consenting, insurance and ownership information and decision making.
Although we cannot predict exactly what impact the effects of climate change or natural hazards will have on specific locations, the information the models provide will help communities and councils prepare for a range of potential impacts.
We’ve undertaken similar projects on the Hutt River / Te Awa Kairangi where flood protection, river restoration and public transport work is now underway.
Why are we doing this?
Advances in flood modelling computer software make it a good time to update these maps. Doing this review also means updated maps can be used in the Kāpiti Coast District Plan review, and the Whāitua Implementation Programme.
Who’s involved?
GW will be working in partnership with the local council, mana whenua, key interest groups, businesses and the wider community.
We have a team of hydrologists and engineers who are experts in their fields of gathering and crunching data about river flows, weather patterns and impacts on the environment.
We work with the technical specialists, local councils and the community to safeguard people’s homes and businesses. We want to ensure continued access to Kāpiti homes and services, roads and infrastructure to support a thriving community and environment.
Flood management plans will be integrated into district-wide plans for future-proofing our communities and environments, while also planning for future growth and development.
What’s the process?
We’re updating the flood hazard maps on the Kāpiti Coast for the following catchment areas:
- Ōtaki River and its tributaries – the Waitohu Stream and the Mangapouri Stream.
- Waikanae River
- Mangaone Stream.
The first step is to analyse rainfall patterns. Once the rainfall is modelled, we will combine this with the information provided on previous events and develop models that help determine where the flood waters might go in the future. This will enable options for minimising the impacts of the flooding on these communities.
We’ll keep you informed along the way
Beginning in December 2024 we’ll keep you updated on how the project is progressing and opportunities for the community to provide feedback and get involved. Keep an eye out on our website, social media channels and newspapers for details on consultation and drop-in sessions to discuss Kāpiti flood hazard modelling and maps for your area.
How can the community be involved?
To ensure we capture as much information as possible to develop these models, we also need your help to understand the impacts from flooded rivers and streams in the Kāpiti area.
We value your knowledge and experience of flooding in the area. We want to understand the risks of flooding and what we it means for you and the community you live in. We want to work with you to build a resilient and prepared community that can still enjoy and flourish in the dynamic environment.
We’d like you to share any photos or stories you might have from previous flooding events from the following areas:
- Ōtaki River and its tributaries – the Waitohu Stream and the Mangapouri Stream.
- Waikanae River
- Mangaone Stream
Share your photos or stories on Have Your Say.
You can also send an email with any questions you might have about the Kāpiti Flood Hazard Modelling project to floods@gw.govt.nz.
The Mangaone Stream’s headwaters are in the Tararua Forest Park. The river flows in a westerly direction before discharging into the sea at Te Horo Beach.