Who foots the bill for lifting Chch land?
Authorities are unclear who will foot the bill to raise large chunks of Christchurch land predicted to be submerged by rising sea levels within the next century.
A Christchurch City Council-commissioned report by Tonkin & Taylor warned warming seas, the melting of Antarctic ice and the likelihood of increased tsunamis raised the chances of some coastal communities going under water.
The report said the council would need to talk to residents about the level of "tolerable risk" both were prepared to take.
Areas most likely to be affected were South New Brighton, Southshore, Sumner, Brooklands, parts of Linwood and parts of Banks Peninsula.
The Insurance Council of New Zealand yesterday said insurers were responsible for properties and their foundations, not the land they sat on.
The Earthquake Commission (EQC) confirmed it would not pay for a property's floor level to be raised if it was in a flood-prone area, if the work was not required as part of earthquake repairs.
Christchurch Mayor Lianne Dalziel said the report raised "hard questions" that would need to be solved with communities.
Councillor Glenn Livingstone said insurance companies would cover the cost of raising homes to the new flood plain level if they were being rebuilt but it was a grey area if only minor repairs were required.
Parts of the city could end up with a "castle turret effect" with some houses being higher than others.
Insurance council spokesman Samson Samasoni said the report was a "sobering reminder of the very real risks associated with sea level rise". The council had kept insurers informed about potential issues and plans involving flood- prone areas, he said.
"In turn, insurers have assisted the council to understand what insurers require to ensure Cantabrians can continue to enjoy the protection that affordable and sustainable insurance provides."
The EQC's head of land settlement, Zac Berry, said the commission recognised an increased vulnerability to flooding due to land changes as a form of land damage.
It was still working to identify those properties and "determine the form of settlement", he said.
In most cases, EQC settled land claims with a cash payment rather than carrying out remediation.
"Where a consent is required we will complete all work required, including raising the floor level of a property," Berry said.
Dalziel said the district plan review would update the flood management areas to include all land subject to a one-in-200-year event.
Those rebuilding in flood-prone areas needed assurance and the ability to future-proof their homes, she said.
"They also need to know who will pay for what, especially in relation to land levels and increased foundation requirements," Dalziel said.