Losing Ground: Coastal Erosion on Pulau Ubin EarthCache

Coastlines and beaches constantly change. Wind and water are powerful forces, and are able to shape and reshape coastlines in a matter of years. These changes can have severe effects on our both natural ecosystems and man-made structures, but we can do something about it! This Earthcache allows you to learn about the power of these forces on Pulau Ubin and the coastal management that is being carried out to prevent this.

Introduction to Pulau Ubin’s Geography

Pulau Ubin is one of the largest of Singapore’s 50 or so offshore islands, located at the eastern side of the Johor Straits. It is a boomerang-shaped island, about 8 kilometres in length and 2 kilometres at its widest. The island was famed for its light-blue granite, and for the better part of the last century, the island was the site of a number of active quarries which provided stone for the construction of many of Singapore’s earliest buildings. After the quarries closed, the island hosted a number of aquaculture farms and more recently, redeveloped as a nature park managed by NParks.

The island is a treasure trove of biodiversity, where one can find the Singapore’s last remaining large swathes of mangrove forest, intertidal zones and secondary forests. However, human development and activities in and around the island has begun to take its toll on the islands landforms. Coastal erosion, in particular, has become a serious problem in the recent years.

Coastal Erosion on Pulau Ubin

Coastal erosion is the process where sediments on shorelines are shifted from one location to the other by the energy of the wind and waves. It is the dominant force in shaping shorelines that are exposed to these elements, and can create very dramatic changes in a matter of years. You can read in greater detail about the mechanism of this erosion in another Earthcache, “Singapore’s Shifting Sands”.

On Pulau Ubin, studies estimate that in the worst affected locations, 30 – 80 m3 of material is shifted along the shoreline every year. This shift has had devastating effects on the shoreline, causing beaches to disappear and structures by the sea to become dangerously exposed to the waves. Two beaches on the northern shore of the island have been affected by erosion, Mamam and Noordin Beach, and your task in this Earthcache will be learn about the extent of the erosion and the what can be done about it.

Managing Coastal Erosion

The local authorities has been begun to act on the issue of coastal erosion, by first identifying the cause of the erosion and then, taking steps to mitigate it. There are various factors that affect the rate of the coastal erosion, such as:

• the energy of the waves striking the shore: beaches exposed to the open ocean, strong waves or high winds will see a larger rate of erosion

• the angle of the waves: waves that strike the shores at a shallow angle are able to transport more material as compared to those that strike perpendicularly

• the presence of vegetation: exposed shores with little to no vegetation to hold on to sediments will see greater extents of erosion

• type of shore material: hard rocks like granite along the seashore are less easily eroded than loose material like sand

• presence of natural or man-made protective structures: natural structures, such as capes, sand bars, mangrove swamps or shoals can break wave energy, as do similar man-made structures, such as breakwaters and groynes. These serve to protect the shoreline from further erosion

At the various waypoints, you will have to observe the effects of coastal erosion on the shores of Pulau Ubin, learn about what caused them and steps are being taken to reduce the erosion.

The following are the Earthcache tasks arranged by waypoints:

Waypoint 1: [N 01°24.193', E103°58.154']

At this waypoint, you will find information about the erosion that has taken place at along the shores of Pulau Ubin:

1. What are the two causes of the erosion along the shores of island?

2. What are the effects of the erosion at Noordin Beach?

3. From the map, estimate the length of shoreline that where moderate to severe erosion has been observed.

Waypoint 2: [N01°24.095', 103°58.214']

At this waypoint, you will be at a vantage point that will allow you to observe the characteristics of Pulau Ubin’s southern shore where the shoreline is stable.

        4. Describe the characteristics of the southern shoreline, and explain why the shoreline here is relatively stable.

Waypoint 3: [N01°25.108', 103°58.536']

This waypoint is located at Mamam Beach where works have already taken place to stabilise the coast from further erosion.

        5. What man-made structures do you see here, and how do they serve to protect the shoreline from further erosion?

You may log the Earthcache as soon as you visit the sites and collect the answers, but please send us a message with those answers in a timely fashion. We will let you know if anything is not in order. Posted logs without accompanying messages will be deleted in 7 days.

This Earthcache was placed with the permission of NParks