• Video: Coastal communities’ inundation maps released

Video: Coastal communities’ inundation maps released

A coastal inundation report, which highlights the risk facing the region, was presented to the Hastings and Napier councils today. 

The coastal inundation maps were prepared as part of a report, Clifton to Tangoio Coastal Inundation, commissioned jointly by Napier City Council, Hastings District Council and Hawke’s Bay Regional Council. They show the potential impacts of seawater flooding in the year 2100.

Deputy Mayor Annette Brosnan says the maps were modelled on predictions showing what a 1-in-50 and 1-in-100-year severe storm event might look like in 2100, without mitigation measures.

"It's really important information for council as we plan our infrastructure for us to inform decisions around floor levels when people make building consent applications or resource consent applications in our regulatory environment for the next 75 years."

About 2000 Napier properties are affected.

Brosnan says their team was out this afternoon doing some letter drops as well as sending letters to every affected landowner, which gives direct access to the modelling information.

Coastal inundation maps show how coastal areas from Clifton to Tangoio could be affected by future sea level rise.

They were developed by environmental and engineering consultants at Tonkin + Taylor Ltd and peer-reviewed by NIWA. The goal of the mapping exercise is to help inform decision making such as setting minimum floor heights and planning future infrastructure. There is also a legislated requirement from central government to map coastal hazard risks.

Napier Mayor Kirsten Wise says having information that far into the future is essential for helping the community build resilience". 

“We welcome this modelling and mapping because the more information we have about natural hazards, the better we can plan. This information will help us make sound decisions about future infrastructure investment.”

She says the report is a reminder that all coastal communities in New Zealand must continue to adapt and challenge the status quo.

"What works today may not work in years to come.”

By legislation (Building Act 2004), properties within coastal inundation zones must have notes on their property files, which will be accessible through the Land Information Memorandum process. New builds and renovations will benefit from having the modelling in place as floor levels will be set to account for potential inundation impacts.

For councils, the modelling will be considered during building consent and subdivision consent processes, and in land use and infrastructure planning. Napier has already put in place some mitigation measures such as raised gravel barriers, stormwater networks, gravel bunds and pumps.

Updated coastal inundation information, specifically commissioned for use when assessing Building Consent applications, has clarified the risk to properties in Hastings and Napier.

In Hastings, 843 properties had no change to their status, while just over 200 of the previously affected had a reduced risk. Two hundred properties were newly affected.

Hastings District Council’s group manager of planning and regulatory services John O’Shaughnessy said every property would be different depending on land contour and the siting and extent of any proposed building work.

“Very broadly, it means that applications for Building Consent must, under the Building Act and the Building Code, be considered taking into account the natural hazard. There are a number of considerations and potential solutions, so we strongly recommend property owners talk to their design professional or a Council building officer before starting on building plans.”

As well as individually advising property owners, the councils had included the interactive map on the Hawke’s Bay Hazards portal.

Hastings has a drop-in session planned for mid-January to answer questions from newly affected property owners.

In the meantime, owners have been provided with a dedicated email contact for those who would prefer to have their questions answered sooner, or who could not make the drop-in session.