Sea level rise likely to damage inland water infrastructure

31 January 2019

Water New Zealand says that rising sea levels will have a huge impact on water infrastructure many kilometres inland from the coast.

Technical Manager, Noel Roberts says he welcomes the findings of a report released today by LGNZ which attempts to quantify the level of local government exposure to sea level rise, but says the risks won’t be restricted to coastal communities and the impact is likely to be far more costly than the report indicates.

The report estimates that the replacement value of three waters infrastructure associated with various scenarios range from $2.7-b for a one metre rise to $7-b for a three metre rise in sea levels.

But Noel Roberts believes this is figure is conservative.

He says that while a huge amount of infrastructure is built along our coastlines, rising sea levels will also affect salinity levels in aquifers many tens of kilometres inland. This is likely to result in a need for further costly treatment solutions for drinking water.

"Inland wastewater systems will also be under pressure due to rising groundwater levels. In many cases there will be a need to redesign and find new solutions to wastewater systems to mitigate against the inevitable infiltration of ground water into waste and stormwater networks.

“The current piping network has not been designed for projected water levels”

He says there is a need to start addressing these issues now because, while it’s clear that coastal communities will be affected by erosion and more frequent storm surges, there is a need for more information about how the changing climate will affect our overall water network.

Water New Zealand is a national not-for-profit organisation which promotes the sustainable management and development of New Zealand’s three waters (freshwater, wastewater and storm water). Water New Zealand is the country's largest water industry body, providing leadership and support in the water sector through advocacy, collaboration and professional development. Its 1,900 members are drawn from all areas of the water management industry including regional councils and territorial authorities, consultants, suppliers, government agencies, academia and scientists.

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