Singapore: Bio-Engineering Works at Bishan-Ang Mo Kio Park to Prevent Urban Flooding

In Singapore, rainfall statistics since 1980 have shown an increasing trend in the frequency of heavy rainfall events. When designing the expansion of the Kallang River to cater for higher-intensity storms, PUB – Singapore’s National Water Agency – did not adopt the conventional approach of creating a bigger concrete drain. Instead, it worked with NParks to explore how the river could be blended with the picturesque park while carrying a higher flow of stormwater. This could also create more value for the park users.   

The Kallang River runs through Bishan-Ang Mo Kio Park. Previously a concrete canal, it was transformed into a naturalized river with bioengineered river edges that meanders through the park so people can get closer to the water. PUB and NParks, the National Parks Board, worked together with consultants Ramboll Dreiseitl Studios and CH2M Hill Singapore on this innovative drainage improvement project to increase the capacity of the waterway yet providing a useable green space for the public to enjoy.

Before (left) and after (right). Credits: Ramboll Studio Dreiseitl

What does the project consist of?

The redevelopment of the park was under the Active, Beautiful, Clean Waters (ABC Waters) Programme, which is a long-term strategic initiative to enhance the waterbodies and bring Singaporeans closer to water so that they can appreciate and cherish this precious resource.

The overarching goal of the 76.7 million SGD ($56.3 million USD) project, part of ABC Waters Programme and carried out at Kallang River at Bishan-Ang Mo Kio Park, was to enhance the drainage infrastructure within the built environment whilst bringing people closer to water. The project’s main focus was to increase the capacity of the river channel through bio-engineering to prevent the nearby roads from flooding during heavy rainstorms, and to provide a more natural and beautiful area for wildlife and citizens.

PUB launched the ABC Waters Programme in 2006. By integrating the drains, canals, and reservoirs with the surrounding environment in a holistic way, the ABC Waters Programme aims to create beautiful and clean streams, rivers and lakes with enhanced public spaces for the community to enjoy. PUB worked closely with government agencies and consultants to develop watershed masterplans. PUB also solicited public feedback in workshops and outreach campaigns, involving the community, including through an ABC Waters Exhibition in 2007.

Bishan-Ang Mo Kio Park is one of the biggest and most popular parks in Singapore and has not had a major upgrading since it was built in 1988. At the same time, PUB also has plans to upgrade the Kallang River. Given this, NParks and PUB reviewed their individual development plans and the project became a joint collaboration between both agencies.

Political leaders were supportive of the ABC Waters Programme from the onset. One such advocate was Dr. Yaacob Ibrahim, the Minister for Environment and Water Resources. The Programme also received support from the late Mr. Lee Kuan Yew, who was then Minister Mentor. Mr. Lee was impressed with the Programme and said that what is even more important is that everyone must help to keep our waters clean to make ABC Waters a success. 

Credits: American Society of Landscape Architects

What is the innovation?

Extensive research and new technologies: Extensive research was done to test this new technology of soil bio-engineering —10 strategies were tested over an 11-month period. This ensured that the park would function well as a floodplain, which was integral to the success of the project. In the end, a variety of plants and bedding materials were used to stabilize the riverbanks, and a variety of wetland plants were introduced for natural cleaning. The park also includes green roofs and bioswales, which slow down water and help remove coarse pollutants.

Public engagement and education: This was an integral part of the project – getting people out into nature so they appreciate the need for climate adaptation. This project was a more intensive level of public engagement than PUB had ever attempted before, so the residents in the park area were involved already during the design phase of the project, to help them understand the value of the park. PUB also encouraged schools to encourage students to spend time in nature and help them understand the importance of the water management.

Credits: American Society of Landscape Architects

What were the barriers? And how they have been overcome?

Bringing down institutional barriers: PUB and NParks, the two main agencies in charge of the project, had to adjust their goals: PUB, as the water agency, was concerned with creating an efficient stormwater conveyance channel, while NParks was focused on creating a quality living environment. Prior to the renovation of the park, the areas that each agency was responsible for were clearly demarcated. To integrate the waterway into the park, both agencies held many discussions to understand each other’s roles and responsibilities and establish common grounds and goals. This comprehensive process resulted in successfully renovating the park that includes extensive greenery and natural space, but also a new waterway that can retain even more stormwater. 

Community awareness: One of the first flooding events after a heavy rain – now a natural part of the park’s new function – resulted in online comments that the park had been flooded and destroyed. Some residents were unaware that the banks of the river were designed as part of the stormwater conveyance channel. Online articles swiftly corrected the misunderstanding.

Sustainable construction: The development of Kallang River at Bishan-Ang Mo Kio Park was done in a sensitive manner, with efforts taken to reduce tree cutting to the minimal. Concrete from the old canal was reused at various parts of the river and the new park, and trees assessed to be in poor condition were recycled as construction materials for the river embankment or as park furnishings.

Outcomes:

The original 2.7 km long drainage channel has been extended into a 3 km river. The land of the park is now being used in a much more effective way, and parts of the river have been widened to 5 times the original width. The park now also includes vegetated biotopes that cleanse the rainwater runoff before it enters the waterway. The transformed Kallang River at Bishan Ang Mo Kio Park is connected via the drainage network to Marina Reservoir in the city, allowing the water to drain away once the rain stops.

The ABC Waters project at Kallang River at Bishan-Ang Mo Kio Park has won many local and international awards. Some of these accolades include the ‘Landscape of the Year’ Award at World Architecture Festival 2012, the 2012 Waterfront Center Awards’ Environmental Award and more recently, the Honour Award at the 2016 American Society of Landscape Architects Professional Awards.

Co-benefits:

Social: the park creates a more beautiful area for residents and visitors who can take advantage of the natural area that had replaced the concrete canal.

Health: offers more space for recreational outdoor activities within Singapore.

Economic: creates a more appealing area for businesses, and property values’ increase.

Environmental: Biodiversity has increased by 30% in the park with regular sightings of otters, egrets, and more.

Links to further information:

Bishan – Ang Mo Kio Park and Kallang River

ABC Waters homepage

'Here is why you shouldn't be alarmed by pictures of “flooding” in Bishan-Ang Mio Park'

Contact Details:

He Qihui

HE_Qihui@pub.gov.sg