Redrawing Christchurch's electoral boundaries will be the most significant shake-up in a lifetime, a political scientist says.
Census data released by Statistics New Zealand yesterday revealed that almost 10,000 people have left the earthquake-hit Christchurch East electorate in the past seven years, 4000 from Christchurch Central and 2000 from Port Hills.
Selwyn and Waimakariri recorded population booms of 13,000 and 7000 respectively.
The 2011 census was abandoned because of the February 2011 earthquake.
Each Christchurch electorate, apart from Ilam, will be re-evaluated in the Representation Commission's boundary review this year.
University of Canterbury senior political science lecturer Bronwyn Hayward said yesterday that it was difficult to predict how the new boundaries would look before the next general election, but it would be a fascinating debate.
"This hardly ever happens in a lifetime that you get these big generational changes," she said.
This kind of political upheaval was rare in New Zealand and political parties would be focused on "trying to maximise their opportunities to get the boundaries that suit them", Hayward said.
Census acting general manager Sarah Minson said the Representation Commission would have new electoral boundaries drawn up for public consultation next month before the release of final boundaries in April.
"The purpose is to ensure fair representation. It would be silly, for example, for one MP to have 10 people and for another to have 100,000," she said.
Population figures showing changes at a suburb level would be released next week.
Waimakariri District Mayor David Ayers said the effect of the quakes on the district's population had been significant.
There had been rapid growth in some rural areas because of new subdivisions, especially in Kaiapoi, Pegasus, Mandeville and the east and west sides of Rangiora.
"We have always been a fast-growing district but it had slowed down before the earthquakes because of the global financial crisis,'' he said.
''Our current projections are to get to about 60,000 by 2020."
Selwyn Mayor Kelvin Coe said the increase in the general electorate population in Selwyn was "confirmation of what we're seeing on the ground".
"[Selwyn] was one of the fastest-growing districts pre-earthquakes. We have seen a lot of new buildings going up in Prebbleton, Lincoln, Rolleston and West Melton," he said.
Selwyn was well-placed to deal with population increases, with wastewater systems to cater for "quite significant" growth.
Despite the expected changes, next month's Christchurch East by-election will be held under existing boundaries.
However, many of the candidates in that race could be back contesting the seat and its new boundaries a year later.
Greens candidate David Moorhouse expected significant changes for the electorate, but where was "anyone's guess".
Parts of the growing electorates of Wigram and Selwyn could be carved off and redistributed to the Christchurch Central and Christchurch East seats, which had lost voters.
It would also be hard to draw lines on a map that reflected communities of interest, but Moorhouse said large parts of the electorate could simply move west.
Labour's Christchurch East candidate, Poto Williams, said she could not speculate on how that seat may look at the next general election.
"But it will require us [the Labour Party] to work really hard to win the new seat regardless of what the new boundaries look like," she said.
National candidate Matthew Doocey said he was "no expert" on boundary changes but it was clear the electorate was changing.
Other electorate population changes:
Wigram's population increased about 5000, from 60,047 to 65,433.
Ilam's population had little change, decreasing from 59,869 to 59,578.
West Coast-Tasman increased by nearly 3000 (56,309 in 2006 to 59,021 in 2013)
Kaikoura increased by 2500 (56,593 to 59,174).
Rangitata increased nearly 4000 (60,388 to 64,142).
Nelson increased about 4000 (56,088 to 60,058).
Te Tai Tonga Maori electorate, which covers all of the South Island, had a population increase of about 2000, from 59,108 in 2006 to 61,496 in 2013.
Nationwide, the number of people living in New Zealand on census night was 4,242,048 - 214,101 more than at the last census seven years ago.
- © Fairfax NZ News