Residents near the Waimakariri River have been advised to prepare for possible evacuation as the river remains in high flood and continues to rise.

Environment Canterbury said at 5.30pm on Thursday that the flow at the Gorge had exceeded 2400 cubic metres per second and was still increasing.

The river is currently contained within terraces from the Gorge to Highfield Road and controlled by stopbanks. There are two sets of stopbanks,  the primary system is designed for flows up to 4500 cubic metres per second, and the secondary system for 6500 cubic metres per second.

Authorities have identified a vulnerability in the stopbank around Kairaki, which could pose a risk if flows exceed 2500 cubic metres per second.

Residents in the Kairaki and Pines Beach areas have been urged to begin preparing for possible evacuation. Those living on the secondary floodplain, including McLeans Island, Coutts Island, and Templars Island, are also being asked to prepare in case the situation worsens.

Environment Canterbury said it was continuing to monitor the situation closely.