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Home Environment Coastal adaptation Coastal science

Coastal science

We asked independent consultancy Jacobs New Zealand Limited to assess our district for coastal hazards, from Ōtaki in the north to Paekākāriki in the south.

The assessment updates previous coastal hazard assessments of the Kāpiti Coast District shoreline. It identifies areas susceptible to current and future coastal erosion and inundation under various potential magnitudes of sea-level rise over 30, 50, and 100 years. It identifies Council infrastructure, community services and private property vulnerable to those hazards.

The report | Likely effects of sea-level rise | Methodology | Coastal hazards by area | Mapped projected coastal hazards | Concerns raised | Other information submitted by third parties | Media releases | Related links

The report

The report, known as the Kāpiti Coast Coastal Hazards Susceptibility and Vulnerability Assessment [PDF 11.98 MB], is based on robust scientific and technical data. It has been independently peer reviewed by Beca and Greater Wellington Regional Council.

It's made up of two documents:

The report reflects both national and international best practice, and meets the requirements of the New Zealand Coastal Policy Statement 2010 and Ministry for the Environment: Preparing for Coastal Change. Guidance for Local Government.

Since the report was released, there have been updates to international and central government guidance. The Ministry for the Environment and Department of Conservation have confirmed expectations around use of SSP5-8.5, and as a result of the updated advice from the Ministry an addendum [PDF 756 KB] to the Kāpiti Coast Coastal Hazards Susceptibility and Vulnerability Assessment has been released.

This addendum removes the previously highest scenario (RCP8.5+) of sea-level rise for the purposes of coastal hazard assessment work (eg, risk assessments and adaptation planning). We can confirm that scenarios SSP2-4.5 (middle-of-the-road scenario) and SSP5-8.5 (fossil-fuel-intensive scenario) is now used.

Use our coastal hazards GIS map viewer to see how your property could be affected.

A separate but related report has also been prepared for the Takutai Kāpiti Coastal Advisory Panel outlining a possible risk-based approach to coastal hazard planning [PDF 2.43 MB].

This report provides technical advice around what a risk-based planning approach is, summarises what Kāpiti Coast District Council’s obligations are under the Resource Management Act 1991 in applying a risk-based approach, and provides examples of how a risk-based approach may be applied in Kāpiti. The examples provided show how areas within the district could be categorised, depending on the likelihood of flooding occurring under different scenarios. These recommendations (and all other recommendations in the report) are advisory only, and are based on existing technical information previously provided to the Council by Jacobs. The recommendations represent the view of Jacobs and do not represent Council policy.

To support your understanding of the coastal science for the Takutai Kāpiti project, watch Principal Coastal and Hazards Scientist Derek Todd give an overview of our beaches, coastal hazards, and the likely impact on these from future sea level rise.

Methodology

Before starting work on the report, Jacobs documented the methodology to be used, and provided this in report form to Council. This methodology report, Coastal Hazard Assessment Technical Report Volume 1 Methodology [PDF 32.51 MB], has been externally peer reviewed by Beca and Greater Wellington Regional Council, and statements of review are attached at end of it.

Coastal hazards by area

Mapped Projected Coastal Hazards for Kāpiti Coast

We’ve mapped the extent of coastal land on the Kāpiti Coast that may be affected by coastal hazards from projected sea level rise.

View the map and check out the instructional video below for extra tips on how to use it.

Concerns raised

Council has been engaging with interested groups on the coastal science. Feedback has included critique from the group Coastal Ratepayers United (CRU) of the approach taken by Jacobs.

Council responded to those concerns by seeking clarification from the Department of Conservation (DOC) and Ministry for the Environment regarding the use of the New Zealand Coastal Policy Statement (NZCPS) and related DOC and Ministry for the Environment guidance. Our letters to DOC and Ministry for the Environment and the CRU critique (which is appended to the end of those letters), along with central government’s responses, can be found below:

The DOC and Ministry for the Environment responses indicated the approach taken by Jacobs is appropriate. Those responses informed advice provided to the Coastal Advisory Panel, and they are also likely to be drawn upon in guiding future district plan change work.

Other information on coastal erosion and inundation including reports submitted by third parties

 On 31 October 2024 a request was made on behalf of Coastal Ratepayers United (CRU) for an independent report by Dr Willem de Lange to be tabled with Council that includes information on coastal hazards.

Council received the De Lange report, submitted by CRU, in a briefing on 19 November 2024. The report can be found at Coastal Hazard Risk Assessment for the Kāpiti Coast [PDF 21.05 MB], and further information on his work at CRU Coastal Hazard Risk Assessment (including maps and a peer review).

Council notes that the De Lange report was not commissioned or peer reviewed by Council, and the information contained in the report on the coastal erosion and inundation risk in the Kāpiti Coast District has not yet been tested through formal Schedule 1 of the RMA process. Council acknowledges the views of CRU and others shared at the briefing on 19 November 2024 that the De Lange report contests some of the information in reports prepared by Jacobs NZ Ltd for the purposes of the Takutai Kāpiti project.

Updated 12 December 2024