Sea Level Rise Report will help Chch become more resilient
Thursday 9 January 2014
Sea Level Rise Report will help Christchurch become more resilient
Christchurch Mayor Lianne Dalziel has welcomed a Christchurch City Council-commissioned report on the impacts of sea level rise for Christchurch and Banks Peninsula.
“What this report has highlighted for me is the importance of feeding this long-term horizon into our current planning processes, so the timing couldn’t be better as we begin our District Plan Review, which will include a specific focus on natural hazards.
“This report gives us the confidence to proceed with this issue in the first phase of our District Plan Review with an eye to the challenges we may have to confront so that we will be a more resilient city in the future.
“It will also assist us develop a city-wide Resilience Strategy, which is a component of being selected to join the Rockefeller Foundation 100 Resilient Cities Network announced before Christmas,” Mayor Dalziel says.
She says the Council will focus on working closely with the community on working through this and other natural hazard issues that impact on people’s lives.
“The level of community engagement that needs to happen regarding this issue has been largely absent from the decisions that have been made in relation to land use since the earthquakes, so this report gives us a fresh start in terms of building a shared understanding of both the likelihood and consequence of natural hazard risk,” Mayor Dalziel says.
The report, commissioned from environmental engineers, Tonkin & Taylor, is a research paper which updates an earlier report prepared in 1999. This latest report takes into account current international science about the impacts of climate change on sea level rise, as well as the impacts the earthquake sequence has had on land levels in the city’s flood management areas.
The Council has already incorporated earlier predictions for sea level rise into a number of its planning and operational activities, which included the introduction of Flood Management Areas (FMA) to the District Plan that identified low lying and flood prone areas around the coast and along the Styx, Avon and Heathcote Rivers. Modelling of tidal flooding in the FMA includes an allowance for 0.5 metre sea level rise. The FMA rules set higher floor levels for new developments.
Although the updated report states that climate change is not expected to create any new coastal hazards, it identifies that based on a one metre sea level rise by 2115 has the potential to increase the impact and consequence of existing hazards at many locations.
Based on this new projection the report states that finished floor levels for new buildings would need to increase by up to half a metre in areas prone to tidal flooding. However, it recommends that the Council review both the extent of its Flood Management Areas and the associated minimum finished floor levels.
“This would be a prudent approach to the predicted rise in sea level over the next 100 years,” Mayor Dalziel says.
The District Plan review will update the Flood Management Areas to include all land subject to a 1 in 200 year event, taking into account changes in land surface levels following the earthquakes. The modelling will also be updated to include the option of increasing the allowance for sea level rise from 0.5 metre to one metre. This aligns with the Ministry for the Environment guidance and responds to the latest science as presented in the Tonkin & Taylor report.
“People rebuilding in flood prone areas need assurance and the ability to future-proof their homes. They also need to know who will pay for what, especially in relation to land levels and increased foundation requirements, and as I have been saying for some time, we need to look at the most vulnerable areas urgently. It is now up to the Council and the community to work together to address the recommendations in the report.
Lianne Dalziel says the report highlights that the Council needs to plan to avoid development and redevelopment in areas vulnerable to natural hazards.
“The report asks the Council to consider what degree of risk is acceptable for property and people already located in areas vulnerable to the impacts of natural hazards (i.e. tolerable risk). We are told we need to consider when the degree of risk becomes unacceptable, at what level of cost (economic, cultural, social and environmental) the Council is prepared to undertake protection responses.”
“These are hard questions, which is why the recommendation for focused discussion with affected communities is so important.
Lianne Dalziel says she will discuss the issue of sea level rise with the Government, because Christchurch is not alone in terms of developments in vulnerable areas, and how this is handled could set a precedent for other councils.
“We need to be working hand-in-glove with Central Government on this.
“Christchurch could provide a template for addressing these matters, which could potentially lead to a National Policy Statement, which would enable a nationwide conversation to take place. I strongly support the recommendation that the Council develop a city-wide Sea Level Rise Adaptation Strategy in close consultation with affected communities,” Mayor Dalziel says.
The report recommends that the strategy should focus on adaptive management to prepare for the impacts of sea level rise in order to safeguard the community, environment and economy from likely risks, and that there be a phased and flexible approach to implementation.
To read the Tonkin & Taylor report, please click here.