General Debate - The Future of Christchurch

In May I addressed the crisis we are facing in Christchurch following the February earthquake. I said then that knowing the challenges ahead of us in what was the new normal, we needed to engender a sense of hope in the community. Since then I have convened a series of public forums in Christchurch, marrying local expertise and civic engagement to develop a vision of a future 21st century eco-city.

In August I released my report, The Future of Christchurch, with copies going to Minister Brownlee and the parliamentary forum, Environment Canterbury, the city council, and the Canterbury Earthquake Recovery Authority. I thanked the Government for its commendation of the report when I tabled it in Parliament recently.

My report contains 26 recommendations identifying four overarching goals. They are resilience, sustainability, harmony, and beauty. This parallels the council's own plan, which conveys a green message from the people of Christchurch about the kind of city they want. But my report goes further and wider, because a necessary condition of a sustainable, harmonious, and beautiful city is its resilience, and resilience requires us to think ahead.

My report contains 26 recommendations identifying four overarching goals. They are resilience, sustainability, harmony, and beauty

So one of my recommendations is to extend the planning period for the recovery strategy and the city plan from 9 months to 18 months, and stipulate a time horizon of 100 years with identified milestones of 5, 20, and 50 years within that period. It is only within the context of such a long-term horizon that the issue of a city's resilience comes into focus. That addresses two main considerations: the seismic nature of the land and sea-level rise. With regard to the seismicity of the land, we all know that the aftershocks are expected to continue into the indefinite future with an 82 percent chance of a significant shock, over magnitude 5, in the next year. That is a major complication for any rebuild—short term or long term.

We remain uncertain over the true nature of the land under the city. A geotechnical report, commissioned by the royal commission and released last week, regards the land under Christchurch as problematic. The inner-city is built largely on liquefaction-prone soil, making it complex and challenging to construct earthquake-resistant buildings. The ground is only 1 to 1½ metres above the water table, and is riddled with aquifers and streams. The report says the foundation conditions of the city are complex and challenging for geotechnical engineers regarding their performance in strong earthquakes. Buildings on liquefaction-prone soil would need robust, shallow foundations that are often accompanied by deep piles that are anchored to solid rock that is 25 metres below the ground. Tougher, seismic foundation standards need to be considered.

The report concludes: "One may argue that the current philosophy does not address the issues of the overall impact of big earthquakes on a city or a country, and the need for a reasonably quick recovery."

So what might be the limits, when an engineer would acknowledge that rebuilding on the site of the original city should be abandoned? Some engineers have said the limit is a 1:4 chance of a similar earthquake over the next 50 years. In my report, I called on the Government to do two things, prior to the rebuild: first, Greater Christchurch should be declared, by Parliament, to be an issue of national significance. A conference should be convened, after the election—with political leaders, scientific advisers, corporate and civic leaders present—to consider the recovery plan. The conference should address the issue of rebuilding Christchurch on its present location, having regard to the basic features of land contour and composition, waterways, and climate.

Secondly, following the conference, the Parliament should adopt a notice of motion that Christchurch should be rebuilt on its present location, in the event that such a political judgment rests on sound, publicly transparent scientific advice. Concerning sea-level rise, my report recommends an alteration to the city plan, acknowledging a possible sea-level rise of 2 metres by 2100, specifying minimum, finished floor levels accordingly. This would include automatic review of the issue, in light of evolving scientific work in each of the reports of the United Nations Intergovernmental Panel on Climate Change as they come out.

It appears that neither the council's draft city plan nor the draft recovery strategy of the Canterbury Earthquake Recovery Authority focuses on these prior resilience issues, but they will, none the less, determine the fate of Christchurch. I call on the Government to act on these recommendations before it is too late.