Takaka Flood Hazard Risk Under Investigation by Council

The Tasman District Council is in the process of investigating how the Takaka township may be affected in the event of a large flood in the Takaka River. By commissioning the flood modelling it is envisaged that a greater understanding of what may occur in the town and surrounding rural areas will be available to the existing community and assist with future planning options, as well as informing an appropriate Civil Defence response.

Public Open Day
Where: Takaka Bowling Club, 17 Hiawatha Lane
When: 12pm to 6.30pm, Friday 18 November

The results of the modelling will be the subject of a public open day in Takaka on 18 November at the Takaka Bowling Club to discuss and outline the options available to the community in order to identify the community’s preferred response to the flood hazard risk.

The flood modelling work has been made more affordable due to recent technology advances. The Council has obtained detailed land contour information for the Takaka area through the use of LiDAR, an airborne survey tool using light detection and ranging technology to measure the elevation of the land.

Covering the lower Takaka and Motupipi Rivers and their flood plains the model enables Council to simulate flood events of different sizes and durations to see what the impacts might be to the land and built development. The model also allows Council to test different risk management options to see what effect they would have on flood risk within the study area.

The model will provide the Council and Civil Defence groups with valuable information on when and where flooding would close roads and allow advance warnings to be issued to landowners for evacuation of stock or their families should a large flood event appear imminent.

“Our understanding of the flood risk in Takaka to date has largely been based on anecdotal evidence and photos from previous floods” said Council’s River Scientist Eric Verstappen.

“The most recent extreme flood event occurred in July 1983, estimated to have a 1.3% chance of occurring annually (ie an average return period of 75 years).”

“The modelling work gives us information on how a larger 100 year return event might impact on the township and floodplain today, as well as what impact climate change might have in the future.”

Council’s Policy Planner Lisa McGlinchey will be using the model outputs to investigate the future development potential for Takaka.

“This is a complex project which involves a whole community – the model will allow us to investigate peoples’ concerns and fully examine the options available so that we can understand the differing impacts on various parties. The initial model results have already raised some interesting questions – it is a valuable tool to have”.