Posted on January 5, 2021
With climate change causing more extreme coastal erosion and sea level rise, coastal communities are going to have to decide how to adapt. Stuff’s senior Northland reporter Denise Piper looks at two different approaches in two very different seaside localities.
In the Whangārei coastal community of Ruakaka, wind and waves are eroding a riverside reserve and seawater is making six significant pōhutukawa sick.
So the Whangārei District Council is spending $374,000 on a seawall, up to 2.3m high, along with earthworks, protection around the roots of the trees and associated stormwater work.
Parks and recreation manager Sue Hodge said the Princes Road project, to be done some time this year, will protect valued public space, the council’s road and services and pōhutukawa.
It will also improve the current situation, where multiple small sea walls and rocks create a potential hazard to both the estuary and users, she said.
Simon Ellison calls the sea wall “a disaster waiting to happen”, with the major earthworks potentially changing the ecosystem of the area, which is part of a wildlife sanctuary.
He is also worried burying the bases of the pōhutukawa and digging around them will kill the trees. Chopping them down was something the council originally planned to do.
Ellison also fears the seawall could make flooding worse in the area, as flood waters might be unable to escape through the high structure.
But Hodge said arborists and engineers agree the seawall will increase the chances of the pōhutukawa surviving and improve existing drainage problems.
“There is uncertainty about the survival of the trees, but the proposed seawall provides them with the best opportunity,” she said.
While a “soft” approach to erosion – such as dune planting – is generally preferred, in this area it was considered it would not stand up to the volatile wind and wave action, Hodge said.
Managed retreat was also not possible, as the council’s road would have been one of the first things to go, leaving no access to the street’s houses or estuary.
But such an approach cannot be replicated across Northland’s 3200km of coastline of beaches and harbours.
Northland Regional Council – the environmental authority across Te Tai Tokerau – generally discourages hard protection against sea level rise and coastal erosion, said climate change working party chairwoman Amy Macdonald.
Non-structural measures like beach renourishment and dune restoration are encouraged in line with national policy direction, she said.
“Hard structures can provide a temporary solution, but can also create other issues down the track – for example, a seawall can create unintended erosion nearby.
“And in the long-term, relying on hard structures means what’s sitting behind it is really vulnerable if the structure fails or isn’t designed for the sea level rise and more extreme weather events, that are projected to come as a result of climate change.”
Macdonald said Northland’s four councils will be working with tangata whenua, communities and key stakeholders to develop flexible plans for the challenges to come.
But that could mean getting ready to move away from the sea.
“The reality is that the climate crisis will change both where and how many of us live,” she said.
“Coastal erosion, tidal inundation and flooding from the sea are likely to affect many places and, eventually, may displace whole communities, hapū and species.”
Some 200km away from Ruakaka, at Ahipara on the Far North’s west coast, rock walls are falling down and coastal areas without rocks have retreated seven to eight metres in just two years.
Fisherman Patau Tepania (Te Rarawa, Te Aupōuri , Ngāti Kahu, Ngāti Kurī, Ngāi Takoto) has lived on Te Rarawa ancestral land all his life but is saddened by the rapid erosion of late.
“We’ve moved the fence three times in the last two years. We’re worried about it, and we’re also worried about the definition of our boundary lines as opposed to the sea.”
Northland Regional Council’s flood and coastal hazard maps show all of Ahipara’s waterfront houses will be under water in 100 years, with many impacted within 50 years.
Tepania said it will be sad if people lost their homes, but he puts the blame squarely on authorities for allowing such development so close the sea in the first place.
“I think it’s out of our hands. I think we need to let Mother Nature take its course.”
The regional council is now updating its flood and coastal hazards maps, to show how coastal erosion will impact more coastal communities, as well as mapping out the predicted coastline over 100 years.
The maps will be released in the second quarter of 2021, helping Northland’s four councils develop an overall strategy and long-term plans to manage sea level rise.
Each council will include a budget for work in its proposed long term plan, with consultation starting in the first half of 2021.
Tepania said a holistic approach is needed to take care of the health of the sea, the land and the people.
“Being kaitiaki [guardian] includes everything – the whole environment. It’s the little streams, the wind, the rain, the sun; it all has a part to play in that cycle and so do we.”
Te Rarawa insists on no driving on sand dunes, no freedom camping where there are no toilets, respect for the fishing rules and a rāhui on taking pāua from one popular rocky area.
This summer the iwi will continue with its kaitiaki monitoring to ensure people play by the rules, from Ahipara beach to its land south, and up Te One-roa-a-Tōhē (Ninety Mile Beach).
“We’re very open to visitors coming, all we’re asking is that visitors come with respect,” Tepania said.