Flood hazard modelling

The Esk River valley extending from about 350 metres upstream of the Esk River-Mangakopikopiko stream confluence down to the river mouth, including Whirinaki and parts of Bay View. This area can be viewed in an interactive map viewer. 

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Pattle Delamore Partners Ltd (PDP) was engaged by the Regional Council to complete the flood modelling. The methodology developed by Pattle Delamore Partners for the modelling has been peer reviewed by Submergent Ltd. 

The peer review concluded that the model supplied by Pattle Delamore Partners is fit for use in evaluating flood depths and extents in the Esk Valley, to support the identification of flood extent zones.

• Read the Pattle Delamore Partners report
• Read the Submergent report

Property owners within the modelled 100‑year flood hazard area were sent letters in mid‑May 2026. Hastings District Council and Napier City Council sent the letters to landowners. Landowners are asked to pass this information on to tenants or lessees where relevant.

You can access the interactive map viewer on this page to identify if your property is in any other modelled flood hazard zones.
You can use the mouse to click and drag the map to the location of your property, or alternatively, use the property search function to enter an address.

Insurers will assess, underwrite and price risk on a case-by-case basis. Insurers will use a wide variety of information to assess risk, including their own data and models, information from the global reinsurance market and commercially available risk data and analytics. The Regional Council can’t advise on how flood information affects insurance cover. Instead, the Regional Council recommends property owners speak directly with their insurer about how this information may be used.

The Whirinaki stopbank project, currently under construction and being built to standards consistent with those used across Hawke’s Bay and New Zealand, is expected to be completed by January 2027. It is designed to reduce flood risk for parts of Whirinaki, with the residential works and road raising scheduled for completion by the end of August 2026. However, modelling confirms that no flood mitigation structure can completely eliminate flood risk.

Even with the stopbank in place, flooding can still occur in very large events that exceed what the stopbank is designed for. Climate change is likely to increase this risk as larger and more intense floods may cause water to overtop the structure.

The Regional Council regularly reviews data we hold about natural hazards and updates hazard maps across the region. As we update each hazard map, the information is uploaded to the Hawke’s Bay Hazard Portal.

Napier City Council and Hastings District Council will also rely on this information to:

• Include on property files and Land Information Memoranda (LIM) as they deem appropriate;
• Process building and resource consents to ensure that the risk from natural hazards to people and buildings is assessed; and
• Update the District Plan in due course.

The new flood hazard maps represent the most up-to -date assessment of future flood risk for the Esk Valley, Whirinaki and parts of Bay View, north of the railway line. They are based on more recent and comprehensive data than the Category 3 hazard mapping developed in 2023 following Cyclone Gabrielle.

This updated information will inform land use planning ad decisions made by city and district councils as part of their regular statutory obligations, such as processing resource consents, building consents and LIMs.

The Regional Council intends to retire Category 3 in the near future.

For more information about Category 3 and other land categories, visit the Land categorisation information hub. 

Property owners do not need to do anything as a result of this updated flood mapping information.

If you lease or tenant your property to a third party, we recommend you inform your tenant(s) or lessee(s) of the updated flood mapping so that they too are aware of the update.

The Regional Council plays a key role in helping communities feel safer and be more resilient to flooding and extreme weather events. Find out what we are doing to build flood resilience.

Find out more about the Whirinaki flood resilience project. 

A 1% AEP (annual exceedance probability) flood event has a 1% or 1 in 100 chance of occurring in any given year. A 1% AEP event is occasionally referred to as a 1 in 100-year event. We use this event for our flood hazard mapping as it is industry standard best practice.

To get a better understanding of the 1% AEP and other flood-related terms and concepts, watch our flood terminology explainer videos. 

Climate change is expected to increase rainfall intensity and amount of rainfall runoff from the catchment and its smaller tributaries.

This modelling includes those projections and converts them into projections of floodwater depths, flows and volumes, rather than relying only on historical flood data alone.

The Regional Council has an extensive programme of flood modelling underway in other areas in the region. Those locations include Tangoio, Aropaoanui, Dartmoor, Pākōwhai, Rissington and Redclyffe (Napier). This modelling will be completed and made public over the remainder of 2026 and into early 2027.

Flood modelling has also been done to inform flood mitigation design options in other locations such as Wairoa, Pōrangahau, and the nearly completed flood mitigation work in Ōmāhu and Waiohiki.