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Last modified: 29 Jul 2020 10:18am

Picture of a mountain landscape with a braided river flowing through a valley and a snowy mountain behind

The Council has started informing landowners of the latest findings on flooding and coastal hazard risks, and how it’s proposing to manage them in the new District Plan.

This work is part of the current District Plan Review. All Councils are legally required to assess and manage natural hazards risk, such as flooding, coastal erosion and inundation (flooding by the sea), and to consider them in the District Plan.  This now includes that Councils assess the risks from more extreme weather events and how climate change effects over the next 100 years could affect them.

The Council, with the help of Environment Canterbury, has carried out computer-based flood modelling to predict the extent and depth of flooding that could happen during a one-in-200 year and a one-in-500-year flood, says Tim Harris, Council’s Group Manager Environmental and Regulatory Services.

As a result of having to assess the risk from flooding in a 200-year flood event, a much larger area of the district has now been identified as being susceptible to flooding.

“While the biggest change from the current District Plan is the size of the district that is affected in some way, we are proposing to manage flood risks with similar restrictions to what’s in the current District Plan,” says Mr Harris.

The main change the Council is proposing is that any new dwellings built on affected areas would be required to have a higher minimum floor height.

“For the majority of properties the increase is likely to be only a few centimetres,” Mr Harris says.

The changes would only affect new projects, and only on areas of a property that are at risk from flooding.

In the meantime, any new Land Information Memorandum (LIM) reports for an affected property will contain a note indicating that the property may be susceptible to flooding and/or coastal erosion and/or inundation under certain circumstances. The note will also identify the latest technical information held by the Council. It is a legal requirement that councils have to include all relevant information they hold about a property in relation to natural hazards in a LIM.

While such floods aren’t a common event, careful planning for natural hazards is necessary.

“A one-in-200-year flood has a 0.5 percent chance of happening in any given year. However, it’s important we let all affected landowners know of an existing natural hazard and how we propose to manage it in the new District Plan. Keeping our communities safe and protecting our environment is part of our job, so it’s important we do this work. We want to help minimise any negative impact such a hazard might have for them and their assets,” says Mr Harris.

“It’s important to note that any proposed rules for the potentially affected areas are a few years away before having any effect.”

The Council is expecting to notify the Proposed District Plan for formal public consultation by the middle of this year, when people will have the opportunity to make a submission on any of the proposed provisions, including how the flood and coastal hazard areas are mapped.

It’s expected that the new Proposed District Plan will be fully in place by mid-2022, subject to any Environment Court appeals. Until then, the current rules for building and resource consents continue to apply.

For more information, including map with affected areas and all the technical reports, check out the Council’s engagement hub Your Say Selwyn.

If you would like to talk to Council about your affected property can still do that by calling 0800 SELWYN (735 996), emailing contactus@selwyn.govt.nz, or coming into our offices in Rolleston.