Floods

Like many cities, parts of Tāmaki Makaurau Auckland are prone to flooding during storms. Water levels can rise rapidly and unexpectedly during a storm event.

Floods are usually the result of continuous heavy rainfall overwhelming the capacity of natural or designed drainage systems but can also be caused by coastal inundation or even tsunami. They become dangerous if:

Water is very deep or travelling very fast
Floodwaters have risen very quickly
Floodwater contains debris, such as trees or building materials.

Floods can cause injury and loss of life, local evacuations, damage to property and lifeline utility disruption. They can isolate communities, cause stock loss and contaminate waterways.

Weather systems are monitored by MetService. MetService is responsible for issuing weather advisories and warnings.

TYPES OF FLOODING

There are different types of flooding:

River flooding generally happens during heavy rain, when rivers overflow their banks into the floodplain. A floodplain is the flat section next to a river, and these can flood quite regularly. Normal rainfall soaks into the soil, is taken up by trees and plants, and runs off the land to form our streams and rivers. Floods happen when there is too much water and the run-off is too much to be carried by the rivers.
Surface flooding can happen when heavy rain falls either in a small area or in an urban area with lots of hard surfaces that stop rainwater from soaking into the ground. Usually, surface flooding starts quickly but doesn’t last very long. It is often associated with thunderstorms and short, intense rainfall.
Groundwater flooding can happen during periods of unusually high rainfall, when the rising water table causes water to rise out of the ground. Groundwater flooding can bubble up and start flowing along the surface, and can also rise up directly in homes.
Flash floods occur rapidly. They are usually the result of intense rainfall which overwhelms natural or urban drainage systems, and they usually affect small areas. Flash floods often appear as a torrent, can carry rocks, mud and other debris, and can sweep away most things in their path.
Storm surges are produced when high winds push water onshore. They can cause beach erosion and threaten life and property. Storm surges are most common at the coast, where severe weather can cause extreme tides. Storm surges can also happen at large lakes.

HOW TO PREPARE

What do I need to do to be ready?

Check the Auckland Flood Viewer to find out if you live, work or play in an area prone to flooding
Decide what to do if access to your house is cut off or if your house is at risk of flooding, plan to evacuate. If your house is not flooded, it might be better to stay at home
Make a plan, including planning and practicing evacuation routes. The plan should show you the safest routes to higher ground or to your community’s place of safety. If you live in a flash flood area you should have several alternative routes. All members of the household should know where to meet each other, where to evacuate to, and what route(s) to take if you have to leave
If you rent your property, ensure you take responsibility for informing guests of the relevant risks on what to do and how to stay safe
If flooding is expected, enlist some helpful friends to help you move your furniture upstairs
Bring outdoor belongings such as patio furniture, indoors
If flooding is expected, consider using sandbags to keep water away from your home.

Be prepared to evacuate quickly if it becomes necessary, follow your emergency plan, take your emergency bag and pets with you if it is safe to do so
Surface flooding, restricted visibility and slips are possible during severe weather; avoid driving unless absolutely necessary
Be aware that cars, caravans and tree branches float and can become flood debris that causes damage
Do not try to walk or drive through floodwater
Move valuable or dangerous items as high as you can off the floor or out of the flood zone.

Start clearing out and drying your home when rain stops and water recedes
Floodwater may be contaminated, throw away any food and drink that may have been in contact with floodwater including canned goods
Clean up carefully and take care around remaining floodwater
Take photos for your insurer of any items you throw away.