Shifting sands explain 'lost' beach

Newcastle's once sandy beach is now full of pebbles and stones

The mystery of disappearing sand at a Northern Ireland beach has finally been explained by scientists.

While the sand dunes at Ballykinler, County Down, are getting bigger and bigger, across the bay in Newcastle, the once sandy beach has vanished.

Residents and the local council have spent the past few years puzzled by the strange phenomenon, but scientists say the problem is a simple matter of a shifting sea bed.

"Local people noticed that the beach at Newcastle seemed to be disappearing while across the bay, at Ballykinler, sand dunes were becoming larger and more plentiful, said Doctor Andrew Cooper from the Centre for Coastal and Marine Research at the University of Ulster.

Dr Cooper and his colleague Dr Fatima Navas have studied navigation charts from the 19th and 20th century and have discovered a substantial build-up of sand off shore.

Using a computer model, they simulated waves moving across the seabed and found a marked change in how the waves approached the shoreline.

"In the mid-19th century waves carried sand to both ends of the bay, sustaining beaches at Newcastle and Ballykinler but now, the change in wave movement means that the sand is being carried away from Newcastle and toward Ballykinler instead," said Dr Cooper.

Ironically, there is plenty of sand in the system as a whole, the waves have simply moved it away from Newcastle under the present conditions Dr Andrew Cooper Centre for Coastal and Marine Research

"The result is the obvious physical changes that local people have noticed on their coastline, healthy, growing sand dunes at Ballykinler but diminished volumes of sand at Newcastle.

"The sandy beach at Newcastle is really quite a thin veneer and a slight loss of sand exposes the underlying glacial pebbles. This has a dramatic effect on the appearance of the shoreline".

However, the changes to the County Down coast are not a cause for concern.

"Ironically, there is plenty of sand in the system as a whole, the waves have simply moved it away from Newcastle under the present conditions."

The study does present new, crucial information for coastal researchers all over the world however.

It shows that the seafloor changed substantially enough over a 150-year period for it to alter the wave patterns and for them to cause changes in the shoreline over the same timescale.

"This is the first time this type of relationship has been identified and it could be very important for organisations concerned with planning for sea-level rise and coastal defences," Dr Cooper added.

Dr Cooper's and Dr Navas's full report is published in the current issue of the leading international journal "Geology".