Bishan-Ang Mo Kio Park provides a new model for tropical urban hydrology through the instrument of landscape infrastructure, addressing Singapore’s dual need for water supply independence and flash flood management while creating access to a thriving riverine ecology within the dense city. Prior to redevelopment, Kallang River was a clear dividing line between the park and community as a straight fenced concrete canal in dire need of an upgrade. The design team worked together with the park and water authorities to rethink traditional infrastructural approaches in order to maximise land, financial and human resources. The brave move to break the canal and restore the river exceeded the targeted carrying capacity while costing 15% less than the redesigned concrete canal. Simple, yet highly engineered, this blurred line between park and river has transformed the community’s pragmatic perception of urban water systems to a relationship that is proud and close to nature.
With the rapid modernisation and urbanisation of Singapore in the 1960s and 70s, concrete drains and canals were built to alleviate widespread flooding. Likewise, the Kallang River was set within a concrete channel in several key places so that water from heavy monsoons would drain out quickly. As the nation’s longest river, it flows 10km through the centre of the island, from Lower Peirce Reservoir to the Marina Reservoir, also serving as part of the larger system providing drinking water to the city.
Bishan – Ang Mo Kio Park is one of Singapore’s most popular heartland parks. It was constructed in 1988 as a leisure destination and green buffer between the residential new towns of Bishan and Ang Mo Kio. However, the detachment of the park was apparent with the drainage canal demarcating a harsh line.
In 2006, Singapore’s national water agency, PUB, initiated the Active, Beautiful and Clean Waters Programme - a long-term initiative to transform the country’s water bodies beyond their functions of drainage and water supply, into vibrant, new spaces for community bonding and recreation. As part of a much-needed park upgrade and plans to improve the capacity of the canal bisecting the park, the new design integrates the seemingly opposing requirements. And thus, the plan to break down the concrete channel and create a naturalized waterway was conceived for the first time in Singapore.
Rebirth of the River
Designed based on a floodplain concept, people can get closer to water and enjoy recreational activities along the generous river banks when water level is low, and during heavy rain, park land that is next to the river doubles up as a conveyance channel, carrying the water flow downstream, enabling multiple land uses within the park and creating more spaces for communal activities. The re-engineering of the river cross section means that whereas before the channel had a maximum width of 17-24 m at flood capacity, the river can now spread to almost 100m in width. This increases the river’s conveyance capacity by approximately 40%.
Making It Work
Construction of the naturalised river started in October 2009. In a feat of sequenced engineering, works to create the new river started while the canal was still functional. 1D and 2D hydraulic modelling studies of the planned river were made so that the team could predict the water course and design for a more robust and varied river. Complementing the computer simulations, traditional soil bioengineering techniques were proposed to stabilise the new river banks. A site within the park was commissioned to test 12 techniques new to the tropics, developing new knowledge and quelling doubts. Results proved healthy vegetation growth and in a reiterative process, soil conditions, slope and plant root strength were examples of adjustments made to the models. Lastly, design experts and clients invested heavily into the training of construction team, who took the first sketches into built form.
A Vibrant River Park
The alignment of the new river channel integrates meanders and varying widths to create diverse flow patterns which are characteristic of natural river systems, creating ecologically valuable, natural and diverse habitats for biodiversity. The design of the floodplain has also introduced a new typology and quality of public space in urban Singapore – three new bridges, a terraced riverside gallery, river platforms, stepping stones across the river and a water playground fed with naturally cleansed river water are all features that enable one to connect with the river. This ability to get close to water and experience all its natural rhythms and beauty transforms peoples’ sense of responsibility to their environment.
Other new facilities include two playgrounds, two new restaurants, toilets and the landmark “Recycle Hill”, a look-out point built from blocks of concrete recycled from the old channel. The vibrant park is open 24/7 and is at the centre of local life; there are plazas to practise tai chi, fields to play soccer and catch and beautifully crafted benches and nooks for lovers.
No wildlife was introduced to the park, but the presence of the naturalized river has seen the park’s biodiversity increased by 30%. A total of 66 species of wildflower, 59 species of birds and 22 species of dragonfly have been since identified.
The park has the advantageous opportunity to host migratory bird visitors due to the country’s location within the Asian-Australasian Flyway, an area with over 50 migratory species travelling along it. A few surprise visitors have already been spotted, including Zanzibar Red Bishop, native to Africa, the Spotted Wood Owl, native to the jungle forest in Indonesia and the Long Tailed Parakeet, native in the Andaman Islands.
In 2015, a family of five otters called the park home, with their presence capturing the hearts of the community and even the local media’s attention. This is a significant win for all as otters had been spotted only around the coast previously – a testament to the re-naturalisation of the river. The family has grown bigger since, with five new pups joining the famous clan.
The restoration of the river has created a huge variety of micro-habitats, which does not only increase the biological diverseness, but also the resilience of species within the park, making vast improvement to their long term survival ability. With the tropical rainforest climate home to an abundance of lush vegetation, and the area located near to the Malay Archipelago (one of the world’s greatest biodiversity hotspots, second only to the Amazon), the potential for biodiversity is fantastic.
“Wild” and natural is not necessarily more dangerous, the new system is actually a lot safer — even in a heavy flood downpour, the river fills slowly providing ample time for people to comfortably move away from the water to higher ground. A comprehensive river monitoring and warning system with water level sensors, warning lights, sirens and audio announcements are in place to provide early warning in the event of impending heavy rain or rising water levels.
Working together to fulfil multiple objectives
Even before the park was completed, the phenomenon of “self-policing” had been observed with locals looking out for the cleanliness of the park and the safety of others. Now, self-organised interest groups meet regularly and schools have field trips to the park – all a reflection of a changing attitude and ownership towards the river park.
When integrated water management is applied in cities, it often means that the boundaries of agencies are not as clear and have to be redefined. This does not mean chaos, but rather, the opportunity for cross-pollination of ideas. While before, the responsibility of the park laid with the National Parks Board and the drainage channel, PUB, the two agencies collaborated, bringing multi-beneficial results to the community. The graceful and effortless outcome is a result of the team’s determination to see the vision come to life – from the master plan level of land use planning to art and education workshops with children, convincing stakeholders and engaging experts at every level added complexity but robustness to the project. This work model has catalysed similar inter-agency partnerships for many downstream projects.
The holistic approach recognizes that the whole is more than the sum of its parts. Bishan–Ang Mo Kio Park is not just a park and the Kallang River not merely a drainage channel. This is ecological and social infrastructure: the two are integrated and interdependent. The park is an inspiring example of how a city park can function as ecological infrastructure, a smart combination of water source, flood management, biodiversity, recreation, and thanks to personal contact and an emotional connection with water, increasing civic responsibility towards water.
Ramboll Studio Dreiseitl Team:
Engineer: CH2M Hill
Bioengineering Specialist: Geitz & Partners
Horticulturalist: Uvaria Tide
Contractor: Chye Joo Construction Pte Ltd
Product Sources [required for built projects]: LUMBER/DECKING/EDGING
Product Sources [required for built projects]: PARKS/RECREATION EQUIPMENT