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Energy Globe World Award 2017

Finalist in the category Water

Floating Wetlands and Freshwater-Tolerant Mangroves
Submitted by:
Housing & Development Board

The implementation of freshwater-tolerant mangroves and floating wetlands has improved the water quality and reduced the surface runoff into the Punggol waterway. This has also positively affected the local biodiversity.

Initial situation
Due to Singapore's rapid urbanization, many green spaces were lost in favor of infrastructural development. Over the years, around 90% of the mangroves at the Punggol waterway has disappeared. This drastic change has led to the rapid decline of biodiversity and significant reduction of the natural heritage. One key concern for water bodies is the accidental leaching of nitrogen and phosphorus from the soil, resulting in eutrophication of water bodies.

The cultivation of freshwater-tolerant mangroves along the waterway stabilizes the slope along the embankments and slows down the surface runoff into the waterway. Floating wetlands placed in the water bodies help to improve the water quality in their immediate vicinity and beautify their surroundings. More than 35 species of freshwater-tolerant mangroves and 15 species of floating wetlands were therefore implemented along the waterway. This led to the reduction of 20% in nitrates and phosphates and improved the turbidity level by 30%. There has also been a noticeable improvement in biodiversity as the number of animal species has increased from 100 to 114.

The implementation of freshwater-tolerant mangroves is a natural and cost-effective way to slow down sediment runoff into the waterway. HDB collaborated with the National University of Singapore to develop a unique floating wetland system that is modular, has better buoyancy, a higher loading capacity and is easy to transport. Compared to conventional methods of improving the slope stability like reinforced concrete retaining walls or geotextile bags, this system has a lower carbon footprint and is more cost-effective.


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