PUB ready to tackle looming threat of flash floods

SINGAPORE has the infrastructure in place to minimise disruption from flash floods during the oncoming north-east monsoon season, said PUB, the national water agency, yesterday.

However, it warned that these may not be able to "cater to the most extreme of storms".

The authority said that, as of Monday, there have been 14 flash flood days this year.

More could occur in the final two months of the year - traditionally the wettest for the Republic.

There were 36 flash flood days last year, up from 23 in 2011, and experts said causes could include increased urbanisation and climate change.

Assistant Professor Winston Chow of the National University of Singapore's geography department said: "The increasing frequency of extreme weather events, such as intense rain or droughts, is consistent with other scientists' observations on climate change."

Mr Ridzuan Ismail, PUB's director of catchment and waterways, said the growth of urban areas in Singapore has led to more rainwater in developed areas flowing into drainage canals. However, the agency said yesterday that it has adopted a suite of measures to address flood risks.

It has completed 163 drainage projects over the past three years at locations such as Toh Tuck Road and Rochor Canal.

About 133 drainage projects are currently under way, and 23 more will be undertaken by next year.

PUB told The Straits Times that it requires drains to be open in low-lying areas at risk of flooding.

In areas where there are space constraints, drains could be closed and water is let in through inlets instead.

The latter "have the advantage of doubling up as a footpath", and PUB said it ensures both types of drains are "adequately sized".

Mr Chong Kee Sen, president of The Institution of Engineers, Singapore, said: "As long as adequate drainage paths are designed to lead rainwater into the drain quickly and effectively, there is no significant difference between covered drains and drains with grille tops."

PUB encourages building owners to play a role in protecting their properties against floods.

Its Code of Practice on Surface Water Drainage, for instance, requires developers to include features that retain or slow down rainwater.

The agency lists 48 floodprone areas and 55 flooding hot spots on its website.

Flood-prone areas are lowlying places with a history of flooding, while hot spots are areas that are not low-lying but have experienced flash floods.

The Meteorological Service Singapore (MSS) warned on Tuesday that rainfall this month and next will be about 20 per cent above the long-term average of 257mm and 288mm respectively. The first half of this month has already been wetter than usual, with 188mm of rainfall recorded so far.

The MSS also expects short, moderate to heavy thundery showers during afternoons and evenings over the next two months, as the annual north-east monsoon season takes hold. It added: "Heavy rain coinciding with high tides could lead to localised flash floods in low-lying areas."

audreyt@sph.com.sg

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