Singapore uses non-traditional method to create new land at Pulau Tekong

Singapore's First Polder: A New Approach to Land Reclamation

Key Concepts:

• Polder: A piece of low-lying land reclaimed from the sea or a body of water, protected by dykes or embankments.
• Coastal Dyke: A raised structure built to protect a polder from sea level rise and wave action.
• Water Management System: A system of drains, stormwater ponds, and pumping stations used to manage rainwater and prevent flooding within a polder.
• Land Reclamation: The process of creating new land from the sea or other bodies of water.
• Rising Sea Levels: The increase in the average height of the world's oceans, primarily due to climate change.
• Coastal Protection: Measures taken to protect coastlines from erosion, flooding, and other hazards.

Pula Takong Polder Project

Singapore has created new land using a non-traditional method for the first time with an 800-hectare land reclamation project at Pula Takong. This project involves a polder, which uses 50% less sand than traditional reclamation methods. The reclaimed land, about the size of two Tropayo towns, will be used for military training and to free up space on the mainland for new homes and amenities.

Polder Construction and Functionality

The Pula Takong polder is a low-lying piece of land protected by a 10 km long coastal dyke. This dyke reduces Singapore's need for sand during reclamation. Instead of filling the entire area with sand, authorities built the dyke to guard against sea level rise. This is the first time Singapore has reclaimed land below mean sea levels. The dyke stands up to 6 meters high, while the rest of the polder lies about 1.2 meters below average sea level.

A water management system prevents inland flooding. Rainwater is collected in a stormwater pond that can hold the same amount of water as 2,000 Olympic-sized swimming pools. Excess water is channeled through a 45 km long network of drains to a pumping station, which pumps the water out into the sea. The central pumping station also prevents water from stagnating on dry days.

Design and Construction Solutions

The construction of the polder involved various design and construction solutions. Natural materials, such as hardy grass species and natural rock, were used on the surfaces of the coastal dyke to absorb wave impact and mitigate erosion. Excess soil from the stormwater pond construction was used as infilling material, further reducing the volume of sand needed.

The Housing and Development Board (HDB) carried out the land reclamation works, first announced in 2016 by Prime Minister Lawrence Wong, who was the national development minister at the time. HDB drew expertise from the Netherlands, known for its high standards for dyke safety. HDB also worked with N Parks and nature groups to identify and transplant endangered plant species before the works began. Similar species of flora and fauna continue to be observed, and the impact on the surrounding environment is expected to be negligible.

Long-Term Care and Climate Change Adaptation

The polder's long-term care will be managed by Singapore's National Water Agency PUB and the Defense Ministry. The polder offers an effective solution to the challenges posed by climate change, such as intense rainfall and rising sea levels. The coastal dyke protects against sea level rise, while the drainage network prevents flooding during intense storms. Authorities say polders may be used as a coastal protection and reclamation method elsewhere if deemed feasible.

Interview with David, Institution of Engineers Singapore

David, chairman of the civil and structural engineering technical committee at the Institution of Engineers in Singapore, explained how polders work and their significance for Singapore.

• Polder Construction: Polders are constructed by building a dyke around the perimeter of the reclamation area, infilling with sand to a level lower than sea level, and then pumping out the water. This saves a lot of sand compared to conventional reclamation methods.
• Significance for Singapore: The main driver for using polders is the shortage of sand resources. By reducing the quantity of sand needed, Singapore can reclaim more land without relying on imported sand.
• Suitability for Singapore: Polders are beneficial for Singapore. Key factors to evaluate their effectiveness include the value of land created against the construction cost and whether the polder can act as a coastal protection structure.
• Adaptability to Rising Sea Levels: The dyke can be increased in height in the future to protect against rising sea levels. However, the dyke needs to be maintained to protect against damages caused by waves or storms.
• Future Applications: Polders can be applied to a wider area, including offshore islands like Pula Ubin and low-lying areas in the mainland. This can allow Singapore to reclaim bigger land and protect the coastline.
• Conditions Required for Effective Poldering: Polders save sand and allow for application to a wider area. Conventional reclamation requires reclaiming land to a level a few meters higher than sea level, using more sand.
• Guarding Against Rising Sea Levels: Polders are one possible solution for constructing coastal protection structures. The key is whether the coastline or dyke is adaptable to rising sea levels. The dyke can be topped up or designed to be increased in level in the future.

Conclusion

The Pula Takong polder represents a significant advancement in Singapore's land reclamation efforts. By using a polder system, Singapore can reduce its reliance on sand imports, reclaim land more cost-effectively, and adapt to the challenges of rising sea levels and climate change. The success of this project could pave the way for wider adoption of polder technology in Singapore and other coastal regions facing similar challenges.