The High Intensity Rainfall Design System (HIRDS) provides estimates of high intensity rainfall at ungauged locations for a range of return periods and event durations. These surfaces can be used for design storm assessment and in the design of flood protection works and other waterway structures. They can also be used for flood modelling, including flood routing, retention basin design and inundation mapping activities, helping to minimise flood risk within communities across the country. HIRDS uses a regionalised index-frequency method to utilise all available historical rainfall records gathered from multiple agencies. Each surface contains rainfall depth (in mm) for a given average recurrence interval (in years) and event duration (in hours) on a 2 km grid. Version 4 of this data set was prepared in consultation with Regional Councils and was funded through an Envirolink Tools Grant. See here for more information and its webpage HIRDS . In preparing HIRDSv4, all reasonable skill and care was exercised and the best available data and methods were used. Nevertheless, NIWA does not accept any liability, whether direct, indirect or consequential, arising out of the use of this tool.******************************************Work with this layer in the ArcGIS OpenData Portal****************************************** If you scroll to the bottom of the hub page for HIRDS v4, there’s a button in the lower right to “Open in ArcGIS Online” – click it A new browser tab opens with the so-called “Item details page” for the layer._Item Page Created: 2018-08-02 02:37 Item Page Last Modified: 2025-04-05 16:09Owner: NIWA_OpenData

Rational_Method_HIRDS_V3_REC1