Frequently asked questions

Here are our answers to the questions we get asked the most. If you can’t find your question below feel free to contact us, we’re happy to help.

• What are Auckland Council’s Flooding Risk categories?
  1. Risk Category 1
  2. Risk Category 2
  3. Risk Category 3
• What types of flooding are there?

What are Auckland Council’s Flooding Risk categories?

If your property has been included in Auckland Council’s property risk categorisation process, we can assist you by providing reports and dealing with Council and covering:

Risk Category 1

Properties that Council considers low risk and can be repaired.

Risk Category 2

Properties where Council thinks the risk can be managed and community or property-level interventions will manage future severe weather event risks. This category splits into three sub-categories:

• Risk Category 2A (assessment)
  Council considers that your property needs further assessment and Council needs more information to provide initial categorisation.
• Risk Category 2C (community)
  Council will create and expand flood protection works to reduce the risk of future flooding events.
• Risk Category 2P (property)
  Council may assist with property specific measures are necessary, such as improved drainage, raising houses.

Risk Category 3

Where Council considers that an area in the high-risk category is not safe to live in because of the unacceptable risk of future flooding and loss of life. Homes in these areas should not be rebuilt on their current sites. Council may offer a property buy-out.

What types of flooding are there?

Flooding can be considered as being caused by a combination of failure of five types of systems:

1. Lack of planning by councils. Houses and buildings have been approved to be built in floodplains and councils are not allowed by law to prohibit this.
   
2. Streams and rivers flooding, due to limited channel capacity and blockages. Alterations to the natural flow of water over time, or due to modifications to the channel and floodplain.
   
3. Stormwater networks designed with limited capacity and blockages due to a lack of maintenance. The catch pits, pipeline inlets and outlets designed to convey stormwater into the pipelines regularly block in a storm with debris, leaves and tree branches. Often catch pits are undersized so that they can’t even cope with a small storm event.
   
4. Overland flowpaths improperly designed and maintained. They are intended to safely convey excess floodwater from streams and stormwater pipes and provide freeboard of between 150 mm to 500 mm. However, they are often blocked by fences, structures and outbuildings. Older areas are unlikely to have overland flowpaths and thus there is no redundancy in the stormwater system to deal with extreme events.
   
5. Coastal inundation/backwater. Flooding of land due to high tides and wind. In some instances, the tide will hold back the natural flow of streams and rivers causing flooding upstream.