Climate Sense

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Water resource management and adaptation

initiatives to the challenges of climate

variability and change in Singapore

Chang Chian Wui, Deputy Director Policy and Planning, Public Utilities Board, Singapore

ingapore is blessed with some 2,400 millimetres of rainfall

each year. Unfortunately, it is a small island with only 700

square kilometres of land. The growing population and

economy exert pressure on land use, with land for water catch-

ments competing with industry and housing. The lack of land to

collect and store rainwater, high evaporative losses and lack of

natural aquifers has led Singapore to be considered water scarce

by the United Nations, ranked 170th of 190 countries in terms

of freshwater availability.

The Intergovernmental Panel on Climate Change (IPCC) Fourth

Assessment Report (AR4) estimates that temperature rise in

Southeast Asia over the next century will be similar to the global

mean temperature rise of 2.8°C. It also suggests that sea level will

rise close to a global mean of 21-48 centimetres and changes in

annual precipitation will range from –2 per cent to +15 per cent with

a medium of +7 per cent. The projection is broadly for wet season

rainfall increase and dry season rainfall decrease. Extreme events are

likely to become more intense in the region.

The potential impacts are water scarcity, increased

flooding and rising sea level. To better understand these

impacts, the Singapore Government has commissioned a

vulnerability assessment, to be completed in 2009. The

study is conducted by the local university, together with

a team of foreign experts, and is based on IPCC emission

scenarios and global circulation models. It projects the

effects of climate change in the next century – changes

in ambient temperature, sea levels and currents, storm

surges, rainfall intensity and duration, wind patterns

and intensity and resulting impacts on water availability,

flooding, coastal erosion, land loss and slope stability. The

results will facilitate the identification of new adaptation

measures and a review of existing ones.

Integrated water resources management

As Singapore’s integrated water agency, the Public

Utilities Board (PUB) is responsible for the management

of the entire water loop – from storm water collection

to potable water supply, used water collection and

treatment, water reclamation and seawater desalina-

tion. Singapore’s water strategy can be summarized by

PUB’s corporate tagline: ‘Water for All: Conserve, Value,

Enjoy’. ‘Water for All’ refers to the supply strategy of a

diversified and sustainable supply of water. ‘Conserve,

Value, Enjoy’ emphasizes water conservation and PUB’s

approach to involving stakeholders and the community

in its work.

Water for All

A diversified supply system with four different sources

is in place – local catchments, imported water,

‘NEWater’ and desalinated water. ‘The Four National

Taps’ not only meet long-term needs, they also increase

resilience against climate uncertainties. Three are

primary sources. They are, in effect, the ‘first drops’ of

water obtained from the water catchments or the sea.

NEWater is a secondary source created by recycling.

Regarding local catchments – although Singapore

has very limited land, segregation of storm runoffs from

used water, judicious land use, vigilant surveillance and

strict enforcement have enabled half of the area, includ-

ing housing estates and urban zones, to be tapped for

water catchment. The new Marina Reservoir, completed

daptation

and

itigation

trategies

The Marina Barrage creates a reservoir in the city, alleviates floods and offers an

attractive recreation area

Image: PUB