Sentosa breakwaters and others. =)



Types of breakwater structures. =)

A breakwater is constructed some distance away from the coast or built with one end linked to the coast. Breakwaters may be either fixed or floating: the choice depends on normal water depth and tidal range. A breakwater structure is designed to absorb the energy of the waves that hit it. This is done either by using mass (example: with caissons) or by using a revetment slope (example: with rock or concrete armour units).

Caisson breakwaters typically have vertical sides and are usually used where it is desirable to berth one or more vessels on the inner face of the breakwater. They use the mass of the caisson and the fill within it to resist the overturning forces applied by waves hitting them. They are relatively expensive to construct in shallow water, but in deeper sites they can offer a significant saving over revetment breakwaters.

Rubble mound breakwaters use the voids in the structure to dissipate the wave energy. Rock or concrete armour units on the outside of the structure absorb most of the energy, while gravels or sands are used to prevent the wave energy continuing through the breakwater core. The slopes of the revetment are typically between the ratio of 1:1 and 1:2, depending upon the materials used. In shallow water revetment breakwaters are usually relatively cheap, but as water depth increases,due to the material requirements, the costs would increase significantly.

The ineffectiveness of breakwaters...

Breakwaters are unable to provide complete protection as areas where breakwaters are not constructed, are still left unprotected. The unprotected areas will be prone to more erosion. Erosion of beach deposits also occurs from the foot of the wall. Breakwaters are subjected to damage, and over-topping by big storms can lead to problems of drainage of the water that gets behind them.

The effectiveness of a breakwater...

A breakwater creates a zone of shallow water between itself and the coast, so that the waves will break against it before reaching the coast, increasing longshore sediment transport. Thus, the coast is protected from erosion by the breakwater.

An example of breakwaters. =)

In Singapore, breakwaters are built along the beaches at East Coast Park, as well as Siloso Beach on Sentosa Island.

More about breakwaters...

·         In some coastal areas, people have built breakwaters off the coast but parallel to it in order to protect the coast.

·         A breakwater is usually made of granite.

·         The cost of each breakwater is estimated to be around SGD 1million. 

Purpose of breakwaters. =)

Offshore breakwaters, also called bulkheads, are constructed to reduce the intensity of wave action in inshore waters and thereby reduce coastal erosion. They are constructed some distance away from the coast or built with one end linked to the coast. The breakwaters may be small structures, placed one to three hundred feet(about thirty to ninety metres) offshore in relatively shallow water. They are designed to protect a gently sloping beach. Breakwaters may be either fixed or floating: the choice depends on normal water depth and tidal range. They are made of large pieces of concrete or granite and are spaced about fifty metres from each other. Breakwater construction is usually parallel or perpendicular to the coast to maintain tranquility condition in the port. Most of Breakwater construction depends upon wave approach and considering some other environmental parameters.

When oncoming waves hit these breakwaters, their erosive power is concentrated on these structures some distance away from the coast. In this way, there is an area of slack water behind the breakwaters. Deposition occurring in these waters and beaches can be built up or extended in these waters. However, nearby unprotected sections of the beaches do not receive fresh supplies of sediments and may gradually shrink due to erosion, namely due to longshore drift.

Breakwaters are subject to damage, and over-topping by big storms can lead to problems of drainage of water that gets behind them. The wall also serves to encourage erosion of beach deposits from the foot of the wall and can increase longshore sediment transport.

What are breakwaters???

Breakwaters are hard engineering structures constructed on coasts as part of coastal defence or to protect an anchorage from the effects of weather and longshore drift.