The high water level values (1% AEP + 1 msl) are used to calculate the required height of habitable floors for developments in the coastal inundation hazard zone, as per Unitary Plan rules. The dataset is primarily for the use of Regulatory and is included as part of the “Calculating Coastal Inundation Levels for the Auckland Region” training.

High sea level values for Auckland were collected between 2013 and 2019, via four separate studies:

• In 2013, Auckland Council’s Civil Defence & Emergency Management Department commissioned NIWA to calculate and model coastal-storm inundation elevations for the entire Auckland region, primarily for emergency management purposes. NIWA calculated extreme high-water level values at fixed locations across the region, focusing on the open coasts and harbour areas.

• In 2016, NIWA calculated high water level values for the east coast estuaries.

• In 2020, DHI calculated high water levels for the Parakai/Helensville area to the south of the Kaipara Harbour. Inundation in this area is particularly complex due to the wide, low lying coastal plains sitting above the confluence of the Kaipara river with the harbour.

• Also in 2019, NIWA calculated high water levels for Great Barrier and Little Barrier for 16 sites at ARI scenarios of 1, 2, 5, 10, 20, 50 and 100 years

Details of each study and the high water level calculations are available in Technical Report 2020/024 (Auckland’s Exposure to Coastal Inundation by Storm-tides and Waves December 2020).