Keep off dunes the message after Bay of Plenty beaches take winter battering

The Bay of Plenty's beaches have taken a battering this winter. Photo / File

The Bay of Plenty's beaches have taken a battering this winter between wild storms, tides and the effects of climate change.

Erosion can currently be seen along the coastline, from as far west as Waihi Beach right through to the East Cape.

Coast Care Bay of Plenty reminded beach lovers that erosion was a natural process and the dunes regenerated themselves.

Bay of Plenty Regional Council's Coast Care coordinator Rusty Knutson said sand dunes were a natural buffer between the land and the sea and a healthy dune system was our first line of defence against coastal flooding.

But sand dunes were a dynamic system and we have to expect them to change over time, he said.

Knutson said wild storms and king tides were events that were predicted to become more common due to both rising sea levels and increasing storm intensity as a result of climate change.

"After a big storm lots of sand can be lost from our dunes in a process called erosion. But when the weather settles down and weather patterns change, sand usually builds back up by a process called accretion.

"This is when smaller waves push sand back onto the beach and gentle winds then push sand into the dune system where it gets trapped by our native sand dune plants which rebuilds the sand dune system," he said.

Knutson said a healthy frontal dune, those planted with native grasses (spinifex) and sedges (pingao), also absorbed energy from storm events and reduced damage to both dunes and the infrastructure sitting behind.

They are also able to regrow as they have long, deep root systems when conditions become more favourable, he said.

"So, though it may look like some of our dunes are in danger at the moment we need to remember this is a natural process and they do regenerate themselves over time."

Knutson said if people were concerned about the dunes, the best thing they could do for them was not walk over and trample the fragile native plants.

Pingao and spinifex can grow in sand and survive summer droughts and big waves but trampling over them will kill them, he said.

- Coast Care Bay of Plenty is a coastal restoration programme run in close partnership with local communities, care groups and schools alongside Bay of Plenty Regional Council, Tauranga City Council, Whakatane District Council, Western Bay of Plenty, Opotiki District Council and the Department of Conservation, that aims to restore and protect the sand dunes along our Bay of Plenty beaches.

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