This study presents New Zealand’s exposure to 1% annual exceedance probability coastal flood inundation under present-day and future higher sea levels. The information presented in this study provides researchers and practitioners with locations to focus more detailed investigation on the potential impacts and management implications of coastal flooding under future sea-level rise (SLR).
At a national level, elements at risk are subject to a linear extreme sea level elevation (ESL1) exposure increase in response to rising sea levels. At region and territory levels, ESL1 exposure of elements exhibits non-linear behaviours, with acceleration or deceleration in response to increasing SLR increments and the characteristics of elements at risk in these areas. Moreover, the report reveals that populations and built assets in some regions and territories with major coastal urban areas experience an initial rapid increase of ESL1 exposure in response to sea level rise. In Hawkes Bay, Wellington and Canterbury, exposure of these elements accelerates rapidly to +0.9 m SLR above present-day mean sea-level, before decelerating under higher SLR thereafter. In other regions, population and built asset ESL1 exposure increases at an approximately constant rate in response to SLR.
It is recommended that coastal flood inundation maps and elements at risk exposure information produced in this study should be updated as new LiDAR data are made available.