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Changes to Flood Management in Selwyn

By Lisa Perry and Laurie Atkinson, Planners, Baseline Group | Sep 08, 2023

The destructive effects of natural hazards on people and property are a growing reality worldwide. New Zealand is no exception, with a recent and local example being the Selwyn River flood in July this year. The Selwyn District Council now has two District Plans; the outgoing Operative District Plan and the new Partially Operative District Plan (PODP). Both plans have legal weight, and both need to be considered when deciding what you need permission for when developing your land. A significant change between the plans is how the new plan considers natural hazards, such as flooding. Where the old plan has two maps relating to natural hazards, the new one has 18.

A new requirement under the new plan is for Flood Assessment Certificates for all new dwellings and main buildings, new subdivisions, and additions of 25 m2 or more floor area to existing dwellings or buildings. Flood Assessment Certificates are issued by the Selwyn District Council, certifying if your land, or activity on your land, is likely to be subject to flooding and if so, what the minimum finished floor level needs to be to avoid getting flooded. The requirement predominantly applies within the Plains Flood Management map of the new plan, which covers most of the Selwyn District southeast of the foothills. So, unless you live on a hill, your land is likely to be included.

The specific requirement is to have a finished floor height at least 300 mm above the 200-year Annual Return Interval (ARI) flood event (a flood that has a 0.5 % chance of occurring in any given year). For new subdivisions, a Flood Assessment Certificate will be issued for each new lot created by the subdivision. To obtain a Flood Assessment Certificate, the most significant requirement for developers and individuals will be providing site specific flood information and a site-specific flood hazard assessment prepared by a suitably qualified and experienced person. Dwellings or main buildings on rural sites will require a recent site-specific flood hazard assessment from Environment Canterbury. Subdivisions will require an assessment from a suitably qualified and experienced person confirming flood levels for each lot, and if the land is below the 200-year flood event level, details of minimum floor levels for each lot will need to be provided.

Although adjusting to new requirements can be tricky, but avoiding a Flood Assessment Certificate is not an option and will only delay the resource consent process. As with any new requirement, there will be a period of adjustment to understand what acceptable information on flooding looks like. Over time, more and better information will become available, which will help developers, individuals, and Council officers alike. The intent of the changes is to protect people and property from the devastating effects of flooding. Given future flood predictions in relation to global climate change, protecting you and your property from natural hazards is crucial.

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