Save Singapore's freshwater streams

Lim Han She For The Straits Times 10 Dec 16;

Two at Teacher's Estate are slated to make way for housing. But creative solutions, such as multi-functional spaces, may help them flow, not go

The current drought across the Causeway in Johor highlights water resource issues plaguing Singapore. However, while Singapore may be a small nation state, it has put in place alternative water supply measures. These include desalination plants; expanding local reservoirs; the national water agency PUB's Active, Beautiful, Clean (ABC) Waters Programme; plus efforts to change behaviour to make consumers more resilient.

However, ensuring a reliable supply of water is only part of the equation of becoming a sustainable, resilient and liveable city of the future.

The recent United Nations Habitat III New Urban Agenda 2016 calls for cities to "protect, conserve, restore, and promote their ecosystems, water, natural habitats, and biodiversity, minimise their environmental impact, and change to sustainable consumption and production patterns".

Rivers provide important ecosystem services such as clean water, flood protection, habitats, biodiversity and recreational and social amenities to urban residents. Urban rivers are, however, often highly degraded, modified, polluted and ugly.

River and catchment health are so important that the state of California awarded infrastructure status to its catchments and rivers two months ago. Catchments and rivers are now classified as California's key water supply assets and are eligible for the same forms of financing for maintenance and repair as other water collection and treatment infrastructure.

Singapore has over 8,000km of waterways, which are mostly concrete drains and canals.

Recent ambitious river restoration projects under the ABC Waters Programme have resulted in aesthetically pleasing riverscapes that provide social amenities.

The Kallang River-Bishan Park and Alexandra Canal are two examples. The Kallang River-Bishan Park project is so successful that it won the Waterfront Awards Program 2012 and is often featured internationally as an example of a successful river restoration project.

Other projects such as the Pang Sua Canal reflect the PUB's interest in restoring natural processes to concrete waterways at a smaller scale and effort. Boulders were placed in the canal. In-stream vegetation slows down fast stormwater flow, providing habitats for aquatic and bird life in the area, and aesthetic recreational areas for Bukit Panjang residents.

Admirable though these river restoration efforts are, research in the United States and Europe shows that such projects do not always lead to pre-restoration conditions. Some projects fail completely. This is in part due to imperfect knowledge of how river processes and ecosystems operate.

Common sense says that it is better to avoid river degradation in the first place.

This holds true, especially, if one considers the Lentor and Tagore freshwater streams in Teacher's Estate, Yio Chu Kang, that are slated for destruction when 30ha of mature secondary forest through which they flow is cleared for housing development.

Tagore Stream will be straightened and turned into a canal, while Lentor Stream will be completely filled up. A newly engineered stream will perform Lentor's hydrological role when the development is complete.

Pictures of these freshwater streams in June and July reveal continuous flow, a small floodplain and healthy riparian vegetation, which supports a diverse ecosystem in the small area it occupies.

To develop these streams into concrete drains would be to remove key ecosystem functions, such as water flow regulation during flood and drought periods, natural habitats and biodiversity, for homes and highly managed blue-green spaces.

Part of the forest has already been cleared as you are reading this article, as reported in The Straits Times yesterday. A wildlife shepherding plan initiated by the Urban Redevelopment Authority hopes to relocate rare wildlife such as the Sunda pangolin, flying lemur and globally threatened straw-headed bulbul to nearby green areas such as the Central Catchment Nature Reserve.

To minimise damage to wildlife, vegetation will be cut systematically to force them to move to nearby green areas.

The damage of this systematic clearing is already seen in the freshwater streams. Lentor Stream is more murky than before clearing activities started.

NATURE VERSUS CITY?

It is understandable that Singapore needs land for development, but destroying natural freshwater streams to later restore them at a great cost is counter-intuitive to a society aiming for a sustainable and resilient urban environment.

The question that must be asked is whether nature and the city can truly coexist in land-scarce Singapore. Do we value nature enough to sacrifice some development opportunities? What type of natural spaces do we want in Singapore?

One answer is to start thinking creatively, so that Singapore's natural areas can become multi-functional spaces to avoid having them totally destroyed for development. Pulau Ubin and Chek Jawa are examples of natural areas that have escaped development - for now.

Creative approaches to developing the forest around Teachers Estate include partial development, preserving the natural streams with a buffer zone and providing trails for people to enter the area.

This development scenario maintains some of the key ecosystem services these rivers provide, plus aesthetics and recreational opportunities for Singaporeans and visitors.

Alternatively, leave the area as it is but develop it minimally for eco-tourism by building tracks or boardwalk trails into the forest.

Cost-benefit analysis of current planned development versus alternative development scenarios, taking into account the ecosystem services of these rivers, can help decide how best to use this space and other natural areas for Singapore's long-term benefit.

While Lentor and Tagore streams still exist, they provide the opportunity to start thinking deeper and creatively about how Singapore will develop in the future, especially if it wants to become a truly resilient and sustainable city - not only in the tropics but also globally.

The writer is a lecturer in hydrology at James Cook University, Australia.