Cost benefits of Westport flood scheme tipped to top $200m

The proposed $26 million Westport flood scheme will not provide uniform flood protection across the town, a report says.

Niwa’s report concluded that under what is referred to as an ARI100 / RCP6 flooding scenario, about $212m of damages would be estimated to occur to Westport buildings.

“The work of Niwa thereby confirms significant cost benefits will arise from the investment of $25 million in the proposed Westport flood risk mitigation scheme.”

ARI is the average time period between floods of a certain size, while RCP is the modelling used to predict climate change effects. Both criteria have been used in the modelling for the proposed scheme.

The total cost of $26m incorporates a $1m contingency at this stage.

The consultant for the Westport scheme business case, John Hutchings, said the cost benefit analysis for the proposed scheme was based around a $212m saving in damage to buildings in the worst disaster scenario, using the Niwa modelling, “remembering $100m damage in the 2021 flood”.

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