Christchurch City Council says the coastal suburb of New Brighton may flood at least twice more in the next month.
An unusually high tide forced the Avon River to breach its banks on Wednesday and rise above the sandbags laid after the February quake.
Up to 50 centimetres of water inundated parts of New Brighton Road.
Burwood-Pegasus Community Board chairperson Linda Stewart wants dredging of the riverbed, which she says has risen by two metres since the September earthquake.
But the council says dredging to make the river deeper will not stop flooding.
It says engineers are considering building higher, permanent stopbanks to prevent overflowing.