Queenstown Lakes District Council (QLDC) has released new stormwater flood hazard maps for Wānaka to help Council and the community better understand and plan for flood risk in the area.

The maps identify potential flood risk from extreme rainfall events to properties in the Wānaka and Albert Town areas and are publicly available online using a GIS map tool.

The maps are accessible from this link: https://www.qldc.govt.nz/stormwater-hazard-maps

Residents and property owners can zoom in on any property and identify the potential flood risk.

QLDC Strategy and Asset Planning Manager Mark Baker said similar assessments are being completed for all townships across the district and are due to be released later this year, through to 2024.

“The modelling has been completed to better understand the flood hazard in the district. The maps will inform our stormwater investment programme and help the community to understand possible flood risk in their area and for their property,” he said.

Two maps have been produced based on the same modelling results.

One map indicates possible water depth caused by stormwater flooding. The other indicates any potential hazard affecting people, property or vehicles, and is based on a combination of water depth and velocity.

The maps were created using a computer model that calculates how, when and where rainwater flows accounting for climate change, local topography and stormwater drainage such as pipes, basins, creeks, bridges, culverts and soak pits.

Environmental factors such as soil characteristics and where rainwater moves slowly or soaks into the ground are also factored into the model.

Council has sent owners of properties within the flood assessment areas a letter advising them that potential flood information will appear on a Land Information Memorandum (LIM) if one is requested for their property.

“Property owners don’t need to take any specific action as a result of this modelling. However, we do recommend they take a look at the maps and understand any potential risk, especially if they have plans to subdivide or build. This new information will be used to inform consent processes and our consent officers will be able to provide advice for each specific situation as it will depend on the property and proposal,” said Mr Baker.

He added the modelling would further inform QLDC’s stormwater investment programme.

“Currently we have multiple stormwater projects underway in Wānaka and across the district. These include the upgrades taking place at Stone Street, Bullock Creek, Aubrey Road, Rata Street and Anderson Road. Work ranges from pipe upgrades to new soakage pits, a stormwater detention facility and stormwater flow diversion and treatment. We also have budget earmarked in the 2021-2031 Ten Year Plan to investigate what further investment might be required.”

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