The ‘accommodate’ grouping is a set of options that enable continued use of coastal land but existing development is adjusted or new development is designed to anticipate the hazard risk. Examples include raising ground and/or floor levels of buildings, requiring relocatable houses, or providing alternative inundation pathways.
A key issue with some of the accommodate options, particularly raising floor levels, is that they are unlikely to be viable with progressively rising sea levels. While houses could continue to be raised above the maximum expected sea and storm level, infrastructure servicing will become problematic and costly, particularly road access.
Download the (pdf 68 KB)Accommodate option summary poster.
Council’s existing Inundation Practice Note provides non-statutory guidance to determine minimum ground and floor levels for subdivision, new buildings, and major alterations to existing buildings in inundation prone areas.
The practice note provides guidance to support Tasman District Council and Nelson City Council building and resource consent processes. The guidance ensures that new buildings and major alterations are built to mitigate a 1% annual exceedance probability (AEP) inundation ‘design event’ for seawater and/or freshwater inundation. A 1% AEP inundation event has a 1% chance of occurring in any year.
In coastal locations, the practice note also includes consideration of at least 100 years of projected sea level rise, following the Ministry for the Environment’s Coastal Hazards and Climate Change Guidance 2017.
Application of the practice note ensures that new buildings and major alterations to existing buildings are designed in a way that allows buildings to remain resilient from inundation over the expected lifetime of the building, taking into consideration climate change effects.
View the Nelson Tasman Inundation Practice Note 2019 (pdf 994 KB)
Resource and building consent decisions are made with the most up to date natural hazards and sea level rise data available at the time they are granted. Consequently, a building constructed today may have different requirements for minimum ground and/or floor levels in comparison to a building constructed 15 years ago, because of improved local data (such as modelling) and updated national sea level rise guidance. There will also be a range of local factors that will influence site specific minimum ground and/or floor level requirements, which means comparisons cannot always be made between sites in close proximity, including within local neighbourhoods.
In our district there have been a small number of relocatable houses built in coastal locations in recent years, recognising the site specific natural hazards risks these locations are subject to over the longer term.
One example is a relocatable house built adjacent to the Coastal Highway and the Moutere Inlet which featured on the TV programme ‘Grand Designs New Zealand’ (as seen below with presenter Chris Moller). In 2017, the Council received a resource consent application to construct this house on very low-lying land. Parts of the site are just at, or slightly above, current mean high water springs (MWHS) and the setback between the proposed house and MHWS was only 7 metres at the closest point. As such, the development is subject to seawater inundation and erosion hazard and required mitigation.
The habitable parts of the house were designed to be relocatable so they can be moved if sea level rise makes living on the site untenable. The foundation of the house is constructed from durable material to reduce the effects that inundation will have on the house in the medium term. Through the building consent process, the Council required that a hazard notice be placed on the property title (under sections 72 and 73 of the Building Act 2004). This notice warns future property owners of the natural hazard risk which, from a legal perspective, provides some protection for Council if there is subsequent damage as a result of the natural hazard.
