Sumner, Clifton beaches alarm

Press, 1 November 1979, Page 4

Sumner, Clifton beaches alarm

The popular Sumner and ’; Clifton beaches may be out lof bounds to small children) (this summer. Erosion has dragged part ’of the beach front out to sea and created deep holes, strong rips, and high sand- i bars.

The beach will be exceptionally dangerous this year and life-saving clubs there are preparing for a busy summer, according to club spokesmen.

The vice-president of the : Sumner Surf Life-saving Club (Mr G. Elmsly) said that swimmers were likely to go further into the water because of the shallow;

beach, and then he swept into a hole or caught in a rip. Last week-end alone about 16ft (1.829 m of sand had (been dragged out to sea, he |said. Access to the Sumner surf club’s clubhouse was threatened because the shore was now within 10ft (3.048 m of the beach entry. But Mr El-

MtWJ. UUI IVII r.l- - said there was no chance of the clubhouse’s being swept away because it w..s anchored into rock by 20ft (6.096 m deep concrete [piles. In the 1950 s the surf club 'buildings had been on the [pier beside Cave Rock. It (had then been passible to (launch boats from the pier. Over the years sandbanks had built up and the club ; had moved to the other side ■of Cave Rock. Mr Elmsly said that the beach front was now being pulled back again and was beginning to look like it did in the 19505. Dr R. M. Kirk, a senior lecturer in geography at the University of Canterbury, has been commissioned bv the Christchurch City Council and the Waimari County Council to make a report on the changing beach front.

He said that the winters of 1977 and 1978 had been iparticularly stormy and the: beaches had been badly; eroded. Last winter had been) relatively calm but the! beaches had -continued to; erode.

Dr Kirk said he thought the erosion was caused by a shift in the channel in the estuary. Sediment dumped round the mouth of the estuary by the outgoing tides was spreading out in a fan-

shaped heap on the sea bed and probably channelling water northwards, changing the shape of the shoreline. Between 1854 and 192 S the channel had gone straight out to sea. said Dr Kirk. Between 1935 and 1946 [it had shifted to the north and from then until 1954 it had continued shifting further north. Dr Kirk has been studying I the channel movements since 1954, and expects to release his findings at the end of this year. The channel, which runs

between the South New ) Brighton spit and Cave (Rock, is about I5()m wide and 6m deep. The director of parks and I recreation for the Christchurch City Council (Mr N. W. Drain) said that the council had put rocks along the front of the car-park by Cave Rock last, year to protect. it from erosion. The. council realised that erosion ; was a serious . problem, and lit would help strengthen any ; buildings which were threatened, said Mr Drain. The president of the Sumner Surf Life-saving Club (Mr M. Lord) said that patrols would have to be more alert this season and the club would acquire mobile warning signs to put in par-j ticularly dangerous places, I such as the end of Cave) Rock, where tides had scored deep holes.