Beach's shifting sands just part of settling-in process

Large quantities of sand are vanishing from Kohimarama's new $6 million beach but experts say there is no need to worry - it will be back again with the next wind change.

In the past few weeks Kohimarama residents and beachgoers have noticed a change in the profile of their new beach where the sand appears to be rapidly disappearing from the western end.

But the city council's beach restoration project manager, Lorenzo Canal, said the beach was simply undergoing a period of adjustment and aligning itself.

Fifty thousand cubic metres of sand was dredged from the Pakiri coast and relocated at Kohimarama last year in a bid to protect damage along the Tamaki Drive seawall.

The new sand covered 800m and elevated the beach by up to 2m - creating a barrier between the sea and the seawall.

Mr Canal said models done before the relocation project started predicted the sand would move with prevailing winds as the beach aligned itself in the first 12 months.

"Earlier work indicated that the beach would taper at the western end and so when we placed the sand on the beach we overfilled that end," said Mr Canal. "The beach is now finding its own profile."

A monitoring report found a predominance of westerly winds had caused fluctuations in the beach profile, with the sand being blown east towards the centre of the beach, as predicted.

Mr Canal said people could expect to see more changes in the next few months. "When it experiences some northeasterly conditions, which commonly occur during summer, the sand will be transported in a easterly direction so it will come back again."

Similar changes occurred at Mission Bay, which was resanded in the mid-1990s.

Mr Canal said a report compiled a year after Mission Bay was completed found there had not been any major sand loss and he expected the same for Kohimarama.

National Institute of Water and Atmospheric Research coastal engineer Doug Ramsay said most relocated beaches experienced a small amount of sand loss in the first 12 to 18 months as the fine particles moved with the wind.

Mr Canal said Kohimarama Beach would be surveyed two-monthly in the next year to monitor what the sand was doing.

Eight other beaches around Auckland are expected to be re-sanded within the next 10 years. They are St Heliers, Pt Chevalier, three Herne Bay beaches, Pt England Reserve, Blockhouse Bay and Taylor's Reserve.