Research report

How exposed are we to coastal flooding?

The research builds on and improves national flood mapping carried out by the Parliamentary Commissioner for the Environment in 2015, and provides a comprehensive picture of the impact of coastal and inland flooding on our national infrastructure, including our buildings, roads, railways, airports, electricity transmission lines, water infrastructure and farms.

The first describes what infrastructure will be exposed for every 10cm of sea level rise (up to 3m), including when coupled with one-in-100-year storms. For example, 30 centimeters of sea level rise (foreseeable in the next 30 years) would expose $18.49 billion worth of buildings around New Zealand to flooding. Further, 2,000 kms of roads, 112 kms of railway tracks, 4,000 kms of water pipelines, 1,600 sq kms of agricultural land, 14 domestic / international airports would also be exposed. Slide up to 1m of sea level rise, and the dollar value of exposure increases to $39 billion.

This report presents New Zealand’s exposure to 1% annual exceedance probability (AEP) coastal flooding events under present-day and future higher sea levels. This information provides researchers and practitioners with locations to focus more detailed investigation on potential coastal flood impacts and management implications in response to future sea-level rise.


National flood risks & climate change