Selwyn District Council is warning that heavy rain in the Rakaia River’s headwaters has caused it to rise rapidly and it is now in “significant flood”.
Because of the high volume of water there is a risk the river may break out onto State Highway 1 and further downstream at the Rakaia Huts, it said.
Water is expected to reach the Rakaia Huts settlement about midnight tonight, but the council said it is advising residents to be prepared and evacuate to friends and family now if they can.
“Door knocking is taking place in the area.”
If there is immediate danger to life or safety, please dial 111, the council said.
If you require support please contact Selwyn District Council on 0800 SELWYN “
Meanwhile, Environment Canterbury says the Waimakariri River is in high flood and is recommending that residents in the Kairaki / Pines Beach area prepare to evacuate.
It’s also suggesting residents of the secondary floodplain (McLeans Island/Coutts Island and Templars Island) also prepare for potential evacuation.
The regional council says flow in the upper part of the river above the gorge has peaked at around 2700 m3/s.
The river is contained within terraces from the Gorge to Highfield Rd, and from this location is controlled by stopbanks.
There are two sets of stopbanks – the primary stopbanks are designed for a flow of 4500 m3/s and the secondary stopbanks are designed for 6500 m3/s.
But it says there is a vulnerability in the stopbank around Kairaki which poses a risk above 2500 m3/s.
Farmers adjacent to flood affected rivers should consider moving stock away from vulnerable areas.