Tides flood roads, erode dunes

An exceptionally high tide yesterday afternoon swamped low-lying coastal areas around Dunedin and washed away vast chunks of the sand dunes between St Kilda beach and Lawyers Head.

Flood-prone streets such as Marne St, Teviot St, and parts of Portsmouth Dr were closed for up to an hour and a-half, although Dunedin City Council roading maintenance engineer Peter Standring said last night, that did not stop motorists ignoring the signs and driving through the water.

The timing and height of tides are governed by the position of the moon and sun relative to the earth.

Yesterday's high tide, about 5.30pm, was known as a king tide - one expected to be particularly high because of the closeness of the moon to the earth.

The National Institute of Water and Atmospheric Research (Niwa) had already predicted yesterday's high tides would be the highest in New Zealand this year.

St Clair Surf Lifesaving Club captain Antony Mason estimated the high tide was about 70cm above normal.

Usually, water rose to about 50cm below the floor and deck of the club's training shed on Otago Harbour.

Yesterday, seawater swamped the deck, popped floor boards in the shed and floated surf skis sitting on the floor.

"It was extreme. I've been involved with the club for 25 years and I never seen a tide like this."

The two high tides yesterday had lowered sand levels on the beach near Lawyers Head "quite dramatically" and eaten into sand dunes at Middle beach, council reserves team leader Martin Thompson said last night.

A small section was eroded from the end of Moanarua Rd.

Contractors would be on the beach at dawn today to try to shore up a rubble wall at the base of the dunes to prevent further damage.

With further high tides and storms predicted through to next week, the council would be monitoring the erosion closely, he said.

allison.rudd@odt.co.nz