Waiwhetū Stream

Waiwhetū Stream flood hazard map is being updated 

Rivers and streams are important features in the Hutt Valley. They provide a valuable connection to the environment, but they also create a risk of flooding. 

Flooding is likely to become more common as climate change brings more severe weather. So, understanding flood risk is more important than ever.  

What will the map show?    

The focus of the flood hazard map is understanding the likely spread and depth of flood waters in a significant, but infrequent, flood from the Waiwhetū Stream.  

People often refer to a flood of this size as a '1-in-100-year flood,' but we call it a 1% annual exceedance probability (AEP) flood. This means there's a 1% chance that a flood of this size could happen in any given year. It's important to understand that it doesn't mean this type of flood occurs exactly once every 100 years.

The map will show the flood extent that would occur during a 1%AEP event, including with the predicted effects of climate change and sea level rise. As well as floodwater from the stream, the map also takes stormwater flooding into account.      

The focus of flood hazard maps

Data, community insights, expert advice and the latest technology were used to create maps that show how flooding of the Waiwhetū Stream would impact the community.   

The maps will help improve public safety and reduce the risk of costly flood damage to property by:   

• Encouraging people who live in areas where flooding could happen to get flood ready.   
• Preventing people from building in areas where flooding could happen.   
• Informing how flood risk will be managed.  

As well as being available on our website, these maps have been provided to Hutt City Council to inform the development of the Hutt City District Plan as hazard layers.  

Waiwhetū Flood Hazard

For more information about the current flood mapping in the area or to request site specific flood advice, visit our flood hazard advice page.