Biodiversity thriving on artificial Punggol waterway

LAURA ELIZABETH PHILOMIN Today Online 1 Aug 16;

SINGAPORE — My Waterway@Punggol, Singapore’s longest artificial waterway and which meanders through Punggol New Town, is now home to a wider variety of wildlife species such as birds, dragonflies and crustaceans, thanks to the efforts by the Housing and Development Board (HDB) to enhance greenery in the area.

Biodiversity in the area is boosted by about 20 per cent, helped by the floating wetlands and a collection of freshwater-tolerant mangrove.

Designed and engineered by a six-man team under the HDB’s Building and Research Institute, these two new environmentally sustainable innovations were implemented in phases between 2011 and 2013 along the 4.2km waterway after it was completed.

Mr Vincent Lim, senior engineer at the institute, said: “For this Punggol waterway, we saw that there are a lot of open areas within the water bodies, so we thought we could make better use of these spaces ... to see how we can intensify greenery.

These solutions, he added, were also targeted to help improve biodiversity and water quality.

The idea for the floating wetlands was chosen because it was part of an ecosystem that would attract birds and fishes while expanding the coverage of Singapore’s mangroves, which have also been part of Punggol’s natural heritage, Mr Lim said.

Inspired by the honeycomb design, the floating wetland system consists of buoyant hexagon-shaped modules that can be assembled into various shapes and sizes to form floating spaces when needed.

A platform of three to four modules can support 360kg of plants and 600kg of human weight, or that of a small maintenance crew.

Then the project team planted 15 wetland species — identified to be the most resilient — onto the floating modules, which were wrapped in coconut fibre and woven mats.

The largest floating wetlands are made up of 130 modules and are close to the size of a four-room HDB flat. These are located near the Heartwave Mall and Jewel Bridge along the waterway.

As most mangrove species are more commonly found in saline conditions such as coastal environments, HDB had to shortlist and test-bed species that could thrive in freshwater.

Young saplings of 35 species of mangrove trees — three of which are endangered native species — were then planted along the banks of a 3km stretch that covers 6,000sqm. The stretch lies near a waterfront Build-to-Order housing project called Waterway Woodcress.

Regular biodiversity surveys conducted by HDB between 2011 and 2013 recorded more than 80 bird species, nine butterfly species and 11 dragonfly species. A second two-year study was started last year and will end next year.

As of June this year, an extra 12 bird species, two more butterfly species and six more dragonfly species have been observed along the waterway. Mr Lim added that there have also been sightings of otters near the floating wetlands.

Both solutions have even helped improve the water quality of the waterway. The roots from plants on the floating wetlands act as water filters, which can remove excess nutrients in the water and allow more sunlight to stream in to form rich food sources for smaller fishes.

“If there’s algal bloom in the water, it kills the fish, and water will turn greenish in colour. Because we use this waterway for kayaking and canoeing activities, we have to consistently keep it clean,” he said.

At the same time, roots from the mangrove trees help naturally stabilise the sloping banks by binding the soil together and reducing the surface run-off of sediments and soil particles into the waterway. Mr Lim said this minimises the occurrence of algal bloom.

In a blog post published yesterday, National Development Minister Lawrence Wong noted that HDB was awarded the Institution of Engineers Prestigious Engineering Achievement Award 2016 for its innovative engineering solutions at the waterway.

“We have learnt much from the engineering solutions deployed here, and will continue to do more. HDB will extend its green innovations to other new estates as well, for example in Bidadari and Tampines North,” he said.

“HDB is also exploring further uses of its floating platform system, such as to support the deployment of solar panels in our housing estates.”