MEDIA FACTSHEET A
Shoreline Restoration Works at Noordin Beach
Pulau Ubin’s shoreline was observed to be eroding, in particular at the northern part of the
island at Noordin Beach, along the mangroves and low cliff faces. This has led to a loss of
coastal and mangrove habitats. The southern coastline was observed to be generally stable
with the exception of a few areas.
Feasibility studies for shoreline restoration efforts began in mid-2015 and concluded in May
2016. These were the steps taken to determine the causes and explore possible mitigating
measures to arrest the erosion.
1. Data Collection and Site Assessment: Existing information such as satellite
images, hydrodynamics, ecological and land use data was reviewed. A series of
topographical, hydrographical, mangroves, sediment and vessel traffic surveys was
also conducted. These allowed us to understand the existing conditions at Pulau
Ubin and determine the extent of erosion and impact on ecological habitats along the
entire shoreline of the island.
2. Coastal Dynamic Assessment and Identification of Erosion: Hydrodynamic and
wave modelling was conducted to assess causes and effects of erosion around the
island. Based on the modelling results, critically eroded areas of importance were
identified for protection/restoration. This included Noordin Beach in the north of the
island.
3. Identification and Evaluation of Mitigating and Restoration Measures: Based on
the identified causes of erosion and affected areas, potential restoration and
mitigation measures were developed and tested via modelling to assess their
effectiveness.
4. Shoreline Stabilisation Plan: Measures that have been developed will be
consolidated in a holistic plan for the monitoring and management of the coastline in
the long term. This plan encompasses monitoring and management measures for
target areas and the rest of the coastline.
Some of the possible causes of erosion which were identified include:
•
Changes in land use – Aquaculture ponds which are no longer in use have led to
breaches in the surrounding bunds over time. The disuse of the ponds’ tidal gates
has also resulted in uncontrolled inflow and outflow of water from the ponds. This has
increased the volume of water leaving the ponds at ebb tide, causing erosion at the
river mouths and mangrove habitats at Sungei Besar and Sungei Mamam.
•
Impacts from waves and ship wakes – The average environmental wave condition
at Pulau Ubin is mild. However, wakes generated by vessel movements at certain
sections of the shoreline with high vessel traffic cause higher wave energy, removing
sediment away from the foreshore, resulting in the shoreline retreating. Wave energy
is greatest in the east (Chek Jawa Wetlands), with its force decreasing westward
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along the shoreline. Vessel wake energy appears to be most prevalent in the narrow
strait between Pulau Ubin and Johor, especially at the northwestern end of the island.
Consultants have carried out modelling studies to assess which measures are likely to be
effective. Based on the identified causes of erosion, possible measures which were
considered to restore the island’s northern shoreline include man-made hard structures such
as groynes, detached breakwaters or headlands as well as the addition of sand to widen the
existing beach.
•
Headlands coupled with Beach Nourishment
The headlands will be constructed with armour rocks and spaced 200 m apart with
nourishing of sand at the shoreline in between. With the headlands acting as control
points, a crenulated-shaped beach can thus be formed, creating a more advanced
shoreline than the current position.
Based on model testing of the different hard engineering measures, this, coupled with
mangrove protection measures, has been assessed to be most suitable in protecting
and rehabilitating the northern shoreline with minimal impacts to the surrounding.
Layout of headlands (left), example of headlands at East Coast Park (right) Photo credit:
Surbana Jurong
•
Mangrove Restoration Measures
Mangrove restoration measures which consist of mangrove toe protection and
rehabilitation were also considered for the eroded mangrove shorelines at Sungei
Besar, Sungei Mamam and Sungei Jelutong to stabilise the shoreline and prevent
further loss of mangrove habitats.
The placement of suitable substrate to fill the mangrove undercuts, as well as rocks
along the toe, helps to protect the shoreline from further wave actions. The wooden
poles form a semi-permeable wave barrier to attenuate the wave actions and
encourage sediment accumulation in front of the toe protection, creating a conducive
environment for mangrove growth. Such mangrove restoration measures have been
tested in Sungei Buloh Wetland Reserve and were found to be effective.
Filling in disused aquaculture ponds will help control the inflow and outflow of water
through the tidal gates, thus regulating the volume of water exchanged during tidal
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cycles and reducing wave impact. This allows for more sediment accumulation,
which encourages mangrove growth. The new mangroves will in turn arrest erosion
to prevent further loss of mangrove habitats.
Photo courtesy of National Parks Board
Part of the works to restore Pulau Ubin’s northern shoreline will also incorporate a coastal
boardwalk approximately 500 m long, part of which extends into the sea. This would allow
visitors to view the island’s coastal mangroves and hills.
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