New houses in low-lying areas of Christchurch may have to be built with higher floor levels if a new council plan is implemented.
Flooding in the Christchurch suburb of St Albans in March. Photo: RNZ / Nicola Grigg
Because the pattern of flooding has changed since the earthquakes, the Christchurch City Council is proposing to widen the city's flood management areas by nearly a third - or even more if a 50-100cm sea level rise is allowed for.
Council natural environment manager Helen Beaumont said new homes needed to be protected from a one-in-200-year flooding event.
"It would be true to say that there are more parts that are more prone to flooding than there are those that are now less prone to flooding," she said.
"There is approximately a 30 percent increase in land area now covered by our flood management areas - most of that increase is due to that change in policy about the mapping."
Mapping and the modelling of flooding from Christchurch's rivers had been matched up and showed the earthquakes had changed flooding patterns, Ms Beaumont said.
"The existing flood management areas are related with the tidal flooding around the estuary and at the coast and also with the main stem of the Avon and the Heathcote and the Styx rivers, and what we're proposing to do is expand into those low-lying ponding areas beyond the main stems of the rivers.
"That would include things like the Flockton area."
The council would consult with the community until 2 May.
