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Rainfall Intensity

Rainfall intensity can be taken off the maps for 50-year average return intervals (ARI). When the co-ordinates of a site are known, site-specific values can be obtained using NIWA’s HIRDS tool at https://hirds.niwa.co.nz/

As NZBC E1 requires that rainwater from events having 2% likelihood of occurring annually shall not enter buildings, the COP uses figures for 50-year Average Return Interval, rather than the 10% probability figures published in E1/AS1.

 

Comparison of 10-year and 50-year Rainfall Intensities

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North Island 10 Minute Rainfall Intensity Map: 50 Year ARI

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South Island 10 Minute Duration Rainfall Intensity: 50-year ARI

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Rainfall intensity maps have been added to this clause. Links to rainfall maps have been included in the calculators.

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