Now that we have established that during the north-east monsoon, waves are approaching the East Coast Park from the south-east, what is the next step? How does this relate to a loss of beach material at the park?

During the north-east monsoon, the waves along the East Coast Park approach at an oblique angle to the shore. When these waves break, the water rushes up the shore diagonally, carrying the sand on the beach along with it in the same (diagonal) direction.

However, once the water starts to recede back to the sea, it will respond to gravity and drag the sand straight down the beach perpendicular to the shore. The water from the next breaker will transport the sand up the beach diagonally again and the cycle continues.

The net result of this is that sand is moved along a beach as a result of what is termed longshore drift. This explains why the beach at the East Coast Park must be protected.

Protection is carried out at the park by the construction of several breakwaters built parallel to the shore. When waves impact on these structures, their energy is dissipated.

Two new breakwaters have been built at Siloso beach, on the southwest shore of Sentosa island. They will serve to protect the beach there, as erosion has been accelerated by the wash from the high-speed ferries plying between the nearby World Trade Centre and the Riau islands of Indonesia.

At almost a kilometre in length, Siloso beach is the longest of three artificial beaches built at a cost of $20 million in 1991. The new breakwaters cost more than $1 million. They are each eighty metres long and are placed about a hundred metres offshore.

Breakwaters are only needed at Siloso Beach and along the East Coast Park because elsewhere in Singapore, longshore drift is negligible. So the next time you find yourself at either beach, be on the lookout for more than just the opposite sex.

Part 1: Erosion along the coastline of the East Coast Park

Reproduced with permission from the site formerly known as 'No Place Like Home', © Kenneth Y T Lim 1995-9