Hundreds of public campgrounds and cherished archaeological sites are at risk of being swamped by flooding amid rising seas, the Department of Conservation (DOC) has warned.

A new report assessed the threat to DOC-managed areas from coastal flooding, with the aim of guiding DOC on how to manage assets like tracks, carparks, boardwalks and ecosystems in the face of sea-level rise.

The report's author, DOC science adviser Andrew Tait, said scientists predicted that sea levels were likely to rise between half a metre to a metre by 2100, increasing the risk of coastal flooding caused by high seas.

"High-impact waves could overcome natural and built defences, flooding land and waterways with seawater and silt for extended periods," Tait said.


"The iconic coastal tracks of Abel Tasman National Park are particularly vulnerable and amongst the 119 recreational locations with assets at risk from coastal flooding."

On top of that, 419 archaeological sites on public conservation land and 331 of DOC's coastal assets were at risk.

They included 20 campgrounds, 127 buildings, a playground and 126 structures, ranging from 41 boardwalks to four steel pedestrian bridges.

Coastal flooding also poses a threat to our coastal ecosystems and threatened species, Tait said.

More than 350 sites where DOC managed ecosystems or specific species had some land at risk, including The Noises Island in the Hauraki Gulf, Horseshoe Lagoon in Canterbury and Maketu Spit in Bay of Plenty.

DOC would use the report to plan for more detailed assessments at regional level.

Tait said managing the effects of climate change was already an important part of DOC's work.

"The New Zealand Coastal Policy Statement provides DOC with policy direction on the management of coastal hazards in relation to climate change," he said.


"The new risk assessment will help to ensure that mitigating sea level rise and coastal flooding risk becomes integral to the way DOC does business."

The report follows another new study showing how climate change would likely shift the distribution of culturally important plants, hampering harvests and putting long Māori traditions and knowledge at risk.

This map shows the locations of around 50 DOC sites at risk of coastal inundation. Source / DOC
This map shows the locations of around 50 DOC sites at risk of coastal inundation. Source / DOC

Researchers focused on two plants that are traditionally used for weaving and as medicine, and that are important to the history and identity of the indigenous Māori people.

One of them was kuta, a soft, golden sedge found in wetlands across New Zealand and especially valued in the North Island, where it was weaved into highly prized mats, hats and basket.

The other was kūmarahou, an endemic shrub that flourished on well-drained clay soils in the northern regions of the North Island during the austral winter.

Māori people used it to treat respiratory ailments.

"Because of polluted water and soil, invasive species, and habitat destruction people are already having trouble finding the resources they need - climate change adds another layer to this issue," said the study's co-author, Dr Priscilla Wehi from Manaaki Whenua - Landcare Research.

"Rather than just looking at whether climate change will make species go extinct, we wanted to know how climate change will affect people's access to plants."