Cyclone Gabrielle flooding

The map shows the extent of the flooding as a result of Cyclone Gabrielle. It does not show the depth of the flooding. There are substantive areas on the map where there was only surface flooding, whereas in other areas there was flooding meters deep.

The map is part of the work the Council would undertake after any major event to establish the extent of any flooding. The results can be used in a variety of ways relating to flood mitigation, such as checking flood modelling and whether any future study is needed on the extent of flooding in a particular area. Many members of the public have also requested to know the flood extents for their own decision-making.  

The map has taken a considerable amount of time to produce because it is based on photographs, videos, satellite photos, local council building inspection information, and ground contours. This has required many hours of staff time to identify where flooding in photos or video is occurring and then plot the areas on the map. Local councils from across the region provided information for the map and were consulted on the results.  

The accuracy of the mapping varies depending on the information available and the area being mapped. For example, a rural area with a flat slope and no structures close to the edge of the flooding would have less accuracy than an urban area where there are multiple photos and videos showing the extent of the flooding.

We can’t comment on how insurance companies will assess risk.

This map, however, shows the flooding that was observed during Cyclone Gabrielle. This map does not model future flooding events, nor show the origin of the flooding that occurred during Cyclone Gabrielle.

In some areas the return period of the flow in the river during Cyclone Gabrielle was in the order of 1:300 years to over 1:1000 years.

The insurance industry, in contrast, generally use flood hazard maps derived from a modelled event such as 1:100 year flood to determine the risk profile.

Any users of the map (including the insurance industry) should be aware of the purpose and scope of this map, and the stated limitations.  If there is any doubt, a user can contact HBRC for more information.

Yes, the Local Government Official Information and Meetings Act 1987 (LGOIMA) requires Councils to include flooding information on LIMS.

We welcome feedback on this map. If you have photos or video that show the extent of flooding that  differs to what appears in the Cyclone Gabrielle Flooding Map, please contact engineering.enquires@hbrc.govt.nz with the subject line “Feedback on Cyclone Gabrielle Flooding Map”.

We will endeavour to upload any changes up as soon as we can.