Christchurch and Banks Peninsula residents are being urged to prepare for possible flooding as the wild weather hammering the North Island tracks south.
MetService says up to 150 to 250mm of rain is predicted in parts of Canterbury from now through to 10am tomorrow. This could cause flooding in some areas of the district, with Banks Peninsula looking likely to be the most affected.
The peninsula is under an orange heavy rain warning from 8am today until 6pm tomorrow.
Another orange heavy rain warning for Kaikoura District and Canterbury north of Amberley is due to expire at 9pm today, while a heavy rain watch is in place for the Canterbury plains and foothills between the Rangitata River and Amberley until 10am tomorrow.
Christchurch City Council General Manager City Infrastructure Brent Smith told RNZ teams have been preparing, particularly in areas expected to feel the greatest impact.
"We're taking our usual precautions by ensuring beach outfalls and wet weather grilles are clear. Pumps and personnel are on standby for the Flockton area and the most critical location in Southshore.
"The upper Heathcote flood storage basins will be functioning as they should during this event, so people may notice fluctuating water levels in the river," Smith said.
"If you know there are leaves blocking sumps or drains near your property, it really helps if you can clear them and place the debris in your green wheelie bin."
Low-lying areas, especially near the Ōtākaro Avon and Ōpāwaho Heathcote rivers, may experience flooding.
"Residents don't need to report surface flooding on roads unless there is a genuine safety issue. The roads are designed to cope with stormwater ponding and water will drain away once rainfall eases.
"Take care and drive to the conditions, do not drive in any floodwaters. If you do need to travel through pooled water, please drive slowly and carefully, and treat all floodwater as contaminated," Smith said.
Lake Forsyth / Te Roto o Wairewa has been closely monitored over recent days as water levels have risen.
"There are strict environmental, safety and consent conditions that determine when the lake can be opened. The lake has to reach a minimum level of 2.3m in summer, and we can only open early if forecasts show it may rise above 2.7m. Based on the forecasts we had at the time, it didn't look like the lake would reach that threshold, so we weren't able to open it."
"Sea conditions have also made opening impossible. We had waves of up to three to four metres over the weekend.
"While the lake cannot be opened at this stage, the team is watching conditions extremely closely and expect to be able to open the lake later this week once conditions allow. We have arranged for resources to be delivered to the site, so as soon as weather conditions improve and a lake opening can be undertaken, this is likely to be Wednesday.
"Given the amount of rain forecast, Little River residents should prepare for possible flooding, and other parts of Banks Peninsula should be aware of the potential for slips and road disruptions. Please be assured we're actively monitoring the situation," Smith said.
Staff also continue to monitor sensors in place on Lighthouse Ro and surrounding area for any land movement, with the area affected by a significant wet weather event last year and remediation works planned to start soon.
Staff and contractors are ready to respond to any issues that may arise throughout the weather event.
