Saving our sand dunes

COAST CARE: The area in the foreground, by Roberts Road, shows where weeds were removed and dune plants put in as part of the Oneroa Walkway development in 2015. In the background the dunes have been almost entirely taken over by weeds. A Waikanae Coast Care group is forming to restore this area to a naturally functioning state to protect the dunes and enhance the biodiversity. Pictures by Liam Clayton
The state of the dunes, full of weeds, before restoratiuon work starts.

A WAIKANAE community group is forming to restore the sand dunes, enhance the area’s biodiversity and help protect a stunning part of the district’s coastline.

The sand dunes along Turanganui-a-Kiwa (Poverty Bay), stretching from “the cut” to the Waipaoa River mouth, both protect the land during storms and provide habitat to a range of species. However, the dunes are almost entirely smothered in weeds.

A public meeting this month at Waikanae Surf Lifesaving Club discussed the formation of a Waikanae Coast Care group — a community group of volunteers who would take charge of restoring and protecting the dunes from Waikanae to Midway Beach.

The model would be based on the Wainui Coast Care group, set up in 2011, through which segments of the dunes are allocated to different groups of Wainui/Okitu residents.

Tairawhiti Environment Centre chair, Gisborne District Councillor and coastal scientist, Doctor Amber Dunn, said Waikanae Beach was a special place that needed some care.

“Waikanae Beach is a stunning part of our region and we should be really proud of it.

“There are not many places in New Zealand like this, with the coast and beach so close to homes and the central business district (CBD).”

Beaches were special places to New Zealanders, and there was an increasing awareness they needed protecting.

“The beach has a different meaning to everyone, from recreation through to a place of peace.”

Restoration of the dunes area, with native dune-specific plants like spinifex and pingao, would enhance the walkway and biodiversity — plants and animals, while protecting the beach and community from storm-induced erosion and future sea-level rise.

Coastal Restoration Trust representative Jim Dahm said all around the country dune systems had been degraded since the arrival of humans.

“They are probably the most significantly altered of all of New Zealand’s major ecosystems.”

There were just several that had been un-altered in the country, in the Catlins and South Westland.

Dunes and forest

When humans first arrived to the shores of Aotearoa, they would have been confronted with an extensive dune system with a great forest behind.

Humans have since sought to take over these desirable, beachfront locations, first transforming them into farmland, and later for housing developments.

In towns and cities, dunes have also been levelled and grassed-over for recreation and picnic areas.

While this can enhance access to beaches, without the dune system the areas become highly susceptible to erosion and lose their biodiversity.

Naturally growing dune grasses, including spinifex and pingao, are known as “sand-binders”.

The plants have long root systems that help catch sand blown off the beach and hold it together. In a big storm this sand is taken off the beach and dunes to form sandbars, which break up ocean swells and form breaks for people to surf on.

This sand is then slowly pushed back onto the beach, and blown into the sand dunes, ready for the next storm.

“Erosion is just how we expect beaches to behave,” Mr Dahm said.

“It is a natural beach function, an exchange of sand between the ocean, beach and dunes, within its own system.”

If this system is altered by removing the dunes, introducing plants that can't hold the sand, or building a seawall, the exchange of sand is altered and the beach can be lost.

Dunes have several vegetation zones, leading from sand-binding grasses in the front to low shrublands, and podocarp forests full of trees like pohutukawa, puriri and rimu in the back.

Restoring New Zealand’s beach zones to these pristine states was not possible, Mr Dahm said.

Many beach areas were highly populated, with roads and houses nearby.

Many plants and animals needed to maintain such ecosystems were extinct, such as moa, and exotic animals grazed on certain plants.

“The focus should be on returning dunes to a naturally-functioning state,” Mr Dahm said.

“Put the right plants in and then get the fauna coming back.”

Initial reservations

Around the country similar projects had been successful, though they were often met with initial reservation.

At a section of Whangamata Beach there were previously no sand dunes, only a grassy bank leading down to the sand. A big storm ripped a chunk out of the bank, threatening the road. Replanting the dunes was suggested as a way to save the beach.

Some residents were resistent at first, but over time the dune plants established themselves and repaired the dune system.

At Wainui Beach in Gisborne, residents had also successfully planted steep, eroding slopes.

Compared to these places, erosion at Waikanae Beach was relatively minor, Mr Dahm said.

It was relatively sheltered and there was an accreting shoreline due to sediment being washed down the Waipaoa River.

The major challenge was the weeds.

Several sections of sand dunes had been replanted when the Oneroa Walkway was established in 2015.

However, the weed source had not been entirely removed, and the plantings had not been maintained.

“It's very weedy,” Mr Dahm said.

“The dunes contain every garden weed known to humanity. Good design and weed maintenance will be essential.”

There was also housing, lots of beach users, and a walkway.

“Whatever you do, you don’t want to impede on that. This is why a community-based approach is a good model, but you also need a relationship with the council,” Mr Dahm said.

A WAIKANAE community group is forming to restore the sand dunes, enhance the area’s biodiversity and help protect a stunning part of the district’s coastline.

The sand dunes along Turanganui-a-Kiwa (Poverty Bay), stretching from “the cut” to the Waipaoa River mouth, both protect the land during storms and provide habitat to a range of species. However, the dunes are almost entirely smothered in weeds.

A public meeting this month at Waikanae Surf Lifesaving Club discussed the formation of a Waikanae Coast Care group — a community group of volunteers who would take charge of restoring and protecting the dunes from Waikanae to Midway Beach.

The model would be based on the Wainui Coast Care group, set up in 2011, through which segments of the dunes are allocated to different groups of Wainui/Okitu residents.

Tairawhiti Environment Centre chair, Gisborne District Councillor and coastal scientist, Doctor Amber Dunn, said Waikanae Beach was a special place that needed some care.

“Waikanae Beach is a stunning part of our region and we should be really proud of it.

“There are not many places in New Zealand like this, with the coast and beach so close to homes and the central business district (CBD).”

Beaches were special places to New Zealanders, and there was an increasing awareness they needed protecting.

“The beach has a different meaning to everyone, from recreation through to a place of peace.”

Restoration of the dunes area, with native dune-specific plants like spinifex and pingao, would enhance the walkway and biodiversity — plants and animals, while protecting the beach and community from storm-induced erosion and future sea-level rise.

Coastal Restoration Trust representative Jim Dahm said all around the country dune systems had been degraded since the arrival of humans.

“They are probably the most significantly altered of all of New Zealand’s major ecosystems.”

There were just several that had been un-altered in the country, in the Catlins and South Westland.

Dunes and forest

When humans first arrived to the shores of Aotearoa, they would have been confronted with an extensive dune system with a great forest behind.

Humans have since sought to take over these desirable, beachfront locations, first transforming them into farmland, and later for housing developments.

In towns and cities, dunes have also been levelled and grassed-over for recreation and picnic areas.

While this can enhance access to beaches, without the dune system the areas become highly susceptible to erosion and lose their biodiversity.

Naturally growing dune grasses, including spinifex and pingao, are known as “sand-binders”.

The plants have long root systems that help catch sand blown off the beach and hold it together. In a big storm this sand is taken off the beach and dunes to form sandbars, which break up ocean swells and form breaks for people to surf on.

This sand is then slowly pushed back onto the beach, and blown into the sand dunes, ready for the next storm.

“Erosion is just how we expect beaches to behave,” Mr Dahm said.

“It is a natural beach function, an exchange of sand between the ocean, beach and dunes, within its own system.”

If this system is altered by removing the dunes, introducing plants that can't hold the sand, or building a seawall, the exchange of sand is altered and the beach can be lost.

Dunes have several vegetation zones, leading from sand-binding grasses in the front to low shrublands, and podocarp forests full of trees like pohutukawa, puriri and rimu in the back.

Restoring New Zealand’s beach zones to these pristine states was not possible, Mr Dahm said.

Many beach areas were highly populated, with roads and houses nearby.

Many plants and animals needed to maintain such ecosystems were extinct, such as moa, and exotic animals grazed on certain plants.

“The focus should be on returning dunes to a naturally-functioning state,” Mr Dahm said.

“Put the right plants in and then get the fauna coming back.”

Initial reservations

Around the country similar projects had been successful, though they were often met with initial reservation.

At a section of Whangamata Beach there were previously no sand dunes, only a grassy bank leading down to the sand. A big storm ripped a chunk out of the bank, threatening the road. Replanting the dunes was suggested as a way to save the beach.

Some residents were resistent at first, but over time the dune plants established themselves and repaired the dune system.

At Wainui Beach in Gisborne, residents had also successfully planted steep, eroding slopes.

Compared to these places, erosion at Waikanae Beach was relatively minor, Mr Dahm said.

It was relatively sheltered and there was an accreting shoreline due to sediment being washed down the Waipaoa River.

The major challenge was the weeds.

Several sections of sand dunes had been replanted when the Oneroa Walkway was established in 2015.

However, the weed source had not been entirely removed, and the plantings had not been maintained.

“It's very weedy,” Mr Dahm said.

“The dunes contain every garden weed known to humanity. Good design and weed maintenance will be essential.”

There was also housing, lots of beach users, and a walkway.

“Whatever you do, you don’t want to impede on that. This is why a community-based approach is a good model, but you also need a relationship with the council,” Mr Dahm said.

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