Letter to The Anguillian
24/9/12
Beach Protection
I read with interest the two articles on the erosion of the Shoal Bay East in The Anguillian of 21 September. I wonder why successive governments have failed to heed the advice of Karim Hodge. It is clear that either they continue to ignore advice or that they lack the political will to enforce whatever legislation there may be. I would be interested to know which of these two is happening.
As Mr. Hodge stated, the mechanisms of beach or coastal erosion are complex and each situation has a distinct mechanism. Sea level rise has been mentioned and may well be an issue. However, I would caution against seizing on this one thing and so ignore the other possible factors that can influence sea level rise. On the subject of sea level rise, I see no erosion of other beaches that can be attributed to this one cause. Indeed many other beaches remain healthy. While sea level rise is occurring worldwide it is quite small to date. Looking at the geology of the island it is clear that in geological time Anguilla has risen out of the sea. The coral rocks at the highest points of the island suggest a vertical displacement of the order of 160 ft. This movement is to be expected because the arc of the Caribbean islands is on the subduction zone where the north Atlantic plate is thrusting below the Caribbean plate. It must be asked if this vertical movement is continuing at this present time. If it is, it could be possible for Anguilla to be still rising out of the sea.
For disaster management and for the economic construction of maritime and near shore structures it is advisable to answer this question. Government has been negotiating with UNAVCO in order to establish a GPS station on Anguilla that would be one of many on the Islands and mainland. This would indicate the horizontal and vertical movement of Anguilla.
If we look at the situation at Shoal Bay East several things become apparent:
• The structures that are there were built without due regard to the volatility of the beaches and without the guidance of set back regulation.
• The coconut trees that are falling show that, prior to this erosion episode, the beach had been stable at that point for about 20 years. It may be longer.
• The fact that the beach can no longer be used for beach chairs at the restaurant suggests that the beach had been there for the time the restaurant has been there. Could that be 10 or 15 years?
• It is interesting that Mr. Webster said that at one time he could walk out to the reef. I remember that some 38 years ago I was thinking of swimming in that general area and saw the fin of a shark close in to the beach indicating deeper water.
• Mr. Webster and Mr. Hodge state that the reef has been reduced in level at that end of the beach.
• The reef in the area is dead.
Other factors were mentioned and a more complete appraisal would be a good idea, however it would appear that the cause of the erosion is the die back of the coral and the reduction in elevation of the reef in successive hurricanes. If this were to be the case then restoring the reef to its original level and profile could be an answer. Done intelligently it could also be inexpensive.In addition to this, there are proven techniques for promoting coral growth on underwater structures. As there is coral die back the reason for this should be determined.
Having considered this we should be careful never to lose sight of what the expert Karim Hodge is telling us about control of the beach and near shore zone. Inappropriate hard structures built on the beach will certainly destroy it in its pristine form.
Each mechanism is different in each case. I remember seeing gun emplacements being revealed by dune recession on the East Anglian coast in theUK. The emplacements were built in 1939 or 1940. Following construction, the dunes had advanced to engulf them and 50 or 60 years later the dunes and the coast were retreating again. On the Essequibo Coast in Guyana, I was building sea defences to protect façade drains and rice fields.Records, some 150 years old, showed that the coast had advanced and retreated several times in the period of 150 to 200 years. There the process is dominated by mud flowing down the Amazon River. On the south coast of Bali in Indonesia erosion and accretion were happening on one 2-mile section of coast. Undue focus on the erosion had ignored the accretion and led to an imperfect understanding of the process and inappropriate corrective action. A completely different set of mechanisms again existed there.
The conclusion to all this is that effective government action must be taken to enable and empower the experts to deal with the situation. We are all aware of the inappropriate structures that hotel developments have put on our beaches. It is time to control this too.
Bill Grandfield
