Strandhill and its Coastal Erosion problem

Strandhill is well known as a lovely seaside resort and world class surfing beach, though one unfortunate problem arising from the large atlantic waves pounding upon the beach at Strandhill is the constantly shifting sands and the ever-present issue of coastal erosion.

The problem of coastal erosion isn’t just in the area of the beach near the cannon, or the nearby sand dunes, but also to an area close to the sewerage treatment works, some distance to the north of the cannon, very close to the western end of the runway at Strandhill Airport.

Sligo Bay, being a large half-moon shaped bay, with a large mass of water constantly being channelled in to a compact area, namely the popular seaside resorts of Strandhill and Rosses Point, both of which have been categorised as being soft coastlines (non rocky).

So when all the power of these north atlantic waves are channelled into these soft coastline areas, we get vast areas of sand being moved constantly around the bay, taking sand from one area and dumping it temporarily in another, then moving it again to a different area before once again dumping it temporarily. This is the catalist of a phenomenon known as coastal erosion.

Take a close look at the map above, showing a birds-eye-view of Sligo Bay, and you can clearly see large deposits of sand having been deposited in Ballysadare Bay, Cummeen Strand and Drumcliff Bay. These sands are being moved around constantly, taking more and more sand from the area of the dunes, out to sea, wearing away the beachfront, and claiming the area for the sea.

During the early 1980’s, Sligo County Council built a rock-based beach defence at Strandhill, this had the desired effect for a while, until it was realised that the problem had just been shifted from one area to another, and that area was about 200 metres to the north of the beach, adjacent to the sewerage treatment works, where the dunes there were now being eroded.

So if coastal protection is enhanced in one area, the problem moves somewhere else, unfortunately leaving Sligo County Council fighting a losing battle. Is there any long-term solution to the problem of coastal erosion?

That’s an impossible question to answer as there are many variables at play.

It is believed that a large part of coastal erosion is the result of global warming. Therefore, in addition to rebuilding beaches and adding sea walls, decreasing greenhouse gas emissions could be beneficial to decreasing this erosion. So its not just a job for Sligo County Council, its up to each and every one of us to play our part.

One solution may be to investigate the possibility of building offshore breakwaters to reduce wave energy before it reaches the beach. Breakwaters are long heaps of rocks dumped parallel to the shore to intercept waves, their effectiveness however, depends on how they are used.

Submerged breakwaters are designed at a height that sits below the mean water level. This means that the structure protects the coastline from erosion without detracting from the aesthetics of the coastline. The idea to utilise submerged breakwaters came about through scientists observing the ability of coastal reefs to act as breakwaters offshore of coastlines. Once waves hit coastal reefs, the wave energy is significantly decreased.

Whether submerged breakwaters would work is not a question I am in the least bit qualified to answer, it is a suggestion worth looking in to. Though how and where to build them would have to be worked out, and we can imagine the Strandhill surfers wouldn’t be too happy about them.