New scientific modelling is offering a more optimistic outlook for parts of Marlborough, with updated data showing a reduced threat of coastal flooding in the Lower Wairau Plain.
Marlborough District Council says its latest hydrodynamic modelling – developed with Earth Sciences NZ -suggests the risk from sea level rise and coastal inundation near Blenheim is lower than previously thought.
The findings mark a significant shift from earlier “bathtub” models, which tended to overestimate flood risk. The new approach instead simulates how water actually behaves – including interactions with rivers, lagoons, stopbanks and coastal barriers – giving a more accurate picture of potential inundation.
Mayor Nadine Taylor says the updated modelling strengthens confidence for future planning, with a smaller area now identified as being at risk.
However, the council is warning the threat has not disappeared. Parts of the central and southern Wairau Plain remain vulnerable even to relatively small rises in sea level, and risks increase significantly under higher sea-level scenarios of around 1.8 to 1.9 metres.
The modelling also highlights how coastal storms can push river levels higher – reinforcing the need for joined-up management of both river systems and coastal environments.
Council says the improved data will help guide future decisions on land use, infrastructure investment, and climate adaptation planning, as part of its long-term strategy through to 2028.
Further work is already underway, including investigations into how rising sea levels could affect groundwater across the lower plain – an issue that could impact farming and land productivity.
For Radio Waatea, while the updated modelling brings some reassurance, it also underscores the ongoing challenge of climate change – and the need for iwi, councils and communities to work together on long-term solutions.
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