coastal protection

Repeated flooding at Chiswell, Dorset, England, led to the construction of large-scale beach defences. This consisted of a sea wall, as shown here, and huge cages of pebbles (known as gabions) laid down on top of the beach. Some of the floods were caused by water soaking through the pebble beach, and flooding the low-lying village behind the beach. To prevent this, engineers placed steel piles down through the beach, diverting water away from the village of Chiswell.

Repeated flooding at Chiswell, Dorset, led to the construction of large-scale beach defences. This consisted of a sea wall, shown here, and huge cages of pebbles (known as gabions) laid down on top of the beach. The gabions are partly covered by shingle thrown up during a storm.

Measures taken to prevent coastal erosion. Many stretches of coastline are so severely affected by erosion that beaches are swept away, threatening the livelihood of seaside resorts, and buildings become unsafe.

To reduce erosion, several different forms of coastal protection are used. Structures such as sea walls attempt to prevent waves reaching the cliffs by deflecting them back to sea. Such structures are expensive and of limited success. Adding sediment (beach nourishment) to make a beach wider causes waves to break early so that they have less power when they reach the cliffs. Wooden or concrete barriers called groynes may also be constructed at right angles to the beach in order to block the movement of sand along the beach (longshore drift). However, this has the effect of ‘starving’ beaches downshore: ‘protection’ of one area usually means destruction of another.

Rock armour refers to large blocks of stone dumped on a beach or at the base of a cliff to reduce erosion. Hard engineering refers to constructed/built devices, while soft engineering refers to natural features such as salt marshes or sand dunes, which may help to protect against erosion.

Coastal protection may also refer to the process of simply leaving the coast to the elements but removing the harmful factor of human population and development.