2. Planning and decision-making context
The management of flood risk in New Zealand is governed by a number of different laws and regulations. It is primarily undertaken by regional councils in conjunction within territorial authorities. Flood risk management is currently under review by the Government under the lead of the Ministry for the Environment.
At present, the Building Act requires that the risk of flooding to a specific building be no more than a 2% probability in any given year (a 2% Annual Exceedance Probability, AEP). Some regional councils stipulate higher levels of protection in their Regional Policy Statements, with a required AEP of 1%.
Since climate change is likely to change flood risk in most regions, expected risk from flooding should be taken into account when existing flood defence systems are reviewed and/or upgraded, so that the same level of protection is provided over the lifetime of the system in question. This is also consistent with the recent amendment to the Resource Management Act, which requires that all persons exercising powers and duties under the Act have particular regard to the effects of climate change (Resource Management (Energy Efficiency and Climate Change) Amendment Act 2004).
A key objective of this report is to outline a cost-effective, credible methodology for councils to assess the likely changes in current 2% and 1% AEP flood risks for their communities.
