'High alert' as beach battered

Dunedin is on "high alert" as its beaches take another hammering from king tides and winter storms that have caused the worst damage since emergency powers were invoked in 2007.

"Reno mattresses", made of steel mesh cages filled with rocks, part of interim protection work done in the past two years, have been exposed by the sea at Middle beach, and an extensive amount of sand has been lost from the Lawyers Head end of the beach.

Freshly dumped sand was being washed away from Middle beach as the tide rose yesterday afternoon.

Dunedin City Council community and recreation services manager Mick Reece said yesterday the high tide was "the last aria" in a drama that had been ongoing for a week.

"It's as serious as it's been since the emergency [in 2007]."

While St Clair beach was holding up well, the profile of the beach had taken a battering further east.

"People are saying they haven't seen that much sand taken off the Lawyers Head end in a long time."

The council had been learning about the oceanography of the area, including that sea movement caused by White Island could be having a significant effect, Mr Reece said.

"The guts of it is the Moana Rua Rd edge is gone, and we're steadily losing the toe of the dune."

It was the first time the reno mattresses had been exposed since they were put in place two years ago. They had slumped forward, and the sea had been eroding the dune behind. Contractors next week would build a new mattress and place it behind and beneath the existing ones.

The battle between surf and turf has been going on since the 1800s, when families began settling what had been a swampy marshland.

In 2007, storms caused major damage to the beaches. The situation was exacerbated by vandalism to "sand sausages" - geo-textile bags filled with sand and laid to protect sand dunes - that were uncovered at the time.