Natural hazards  |  15 Dec 2021

Residents in Christchurch and Banks Peninsula should prepare for widespread flooding tonight as the rain band hitting the district intensifies.

“We are expecting up to 160mm of rain over the next 24 hours so it is likely there will be surface flooding in many parts of our district,’’ says Christchurch City Council Head of Three Waters Helen Beaumont.

"The forecasts have been changing throughout the day but this is shaping up to an extreme rain event – it could be the biggest rain event to hit Christchurch city for several decades.

"If we get as much rain as is currently forecast, there will be widespread flooding of roads and property.

“The most intense rain is due to hit Christchurch and Banks Peninsula between 8 and 11pm tonight.  Fortunately, that coincides with low tide but we are still expecting there to be widespread flooding. If you live in a low-lying area, we advise you to start preparing your property now for potential flooding,’’ Ms Beaumont says.

Civil Defence teams are on stand-by in case they are needed and any homes need to be evacuated.

Council contractors are also working across the city monitoring the roads and the stormwater network. They will be ready to close roads if flooding occurs.

“Public safety is our number one concern and tonight is not a night to be on the roads if you don’t need to be. If you do need to be on the roads, drive slowly and avoid driving through flood waters if possible. If you have to drive through ponded water, go as slow as possible so that you don’t push water onto people’s property, causing damage.

“It’s likely there will be some wastewater overflows as a result of all the rain so treat all flood water that you come into contact with as potentially contaminated.’’

Ms Beaumont says the stormwater storage basins upstream of the Heathcote River, which are designed to ease the pressure on the rivers, are likely to reach capacity overnight. It is likely that tomorrow morning water from the storage basins will need to be released into the Heathcote, which will cause a rapid rise in the water levels. We will control the capture and release of water to reduce the severity of flooding along the river corridor over the next 24 hours.

“People living along the Heathcote should expect some flooding across the roads and onto their properties, and that may increase when we release water into the river,’’ she says.

People living near any of our waterways should not park their cars overnight on the streets that are vulnerable to flooding.

Any residents with concerns about flooding on their property should contact the Council on 941-8999. If anyone has concerns for their safety they should call 111 immediately.