To meet regional council requirements, Hamilton City Council has an ongoing programme to understand the effects of a very rare, and very large, rain event across the city.
This means looking at what would happen if we had the amount of rain predicted in a storm which would occur, on average, once in 100 years. The chance of this happening in any given year is 1%. Even though it's very rare, It's important to plan for this so we can invest efficiently for future stormwater planning and ensure development doesn't create new problems or impact nearby properties.
Mapping of potential flooding in a one-in-100-year event is developed with computer modelling that uses landform information (land contours), climate change information, and known and predicted rainfall and water flow patterns.
When Council receives new or updated data about these potential flood effects on properties in the city we are required by law to make this publicly available upon request. Council uses an online tool, Floodviewer, to host existing and updated data and make it more accessible to the public.
It's important to note this work does not increase the likelihood of flooding within your property boundary during a one-in-100-year rain event, it simply produces data and makes it publicly available. This information can assist landowners in making decisions about future development on their property.
You can search Floodviewer by property address and this webpage carries more detailed information and a comprehensive list of frequently asked questions.
Floodviewer holds a lot of information and can seem quite complex for people not used to working with Council mapping systems. We recommend reading through the FAQs thoroughly before entering the Floodviewer site and attempting to understand the layers of mapping within Floodviewer.
If you have more detailed queries regarding your property or future plans for development we are happy to help. Please contact one of our team to discuss it either by email at City.Development@hcc.govt.nz or by calling 07 838 6699 during business hours.