As part of ongoing efforts to shore up defences against floods due to increasingly frequent extreme weather conditions, the Government plans to spend S$500 million over the next three years to improve drainage across the island. Canals and drains at 16 locations will be upgraded next year.

National water agency PUB said in a press statement on Thursday (Nov 30) that this “continual drainage improvement is part of PUB’s strategy to enhance Singapore’s ability to cope with higher-intensity storms”.

Mr Ridzuan Ismail, PUB’s director of catchment and waterways, explained that with climate change, more intense storms can be expected to occur more frequently in Singapore.

The Meteorological Service Singapore told TODAY that rainfall statistics “show an increasing trend in (the) frequency of heavy rainfall events over Singapore”. There has been almost one more day of very heavy rainfall — with maximum hourly rainfall exceeding 70mm — per decade since 1980, it added.

Flash floods have occurred on 14 days this year so far, compared to 10 last year and six in 2015.

In managing floods, Mr Rizuan said that a more sustainable approach is needed, because deepening and widening drains would take a toll on Singapore’s limited land use.

Apart from PUB’s efforts, property developers can also do their part by making sure measures are in place to slow down rainwater run-off into public drains and to protect developments from floods, he added.

These could be “source” measures to manage rainwater where it falls, for example, by having detention tanks to collect the water at buildings, as well as “receptor” measures at the areas receiving rainwater flow, for example, by installing barriers at flood-prone areas.

ONGOING WORKS

Since 2011, the Government has invested some S$1.2 billion on drainage improvement works. PUB has also completed drainage improvement works at 325 locations to increase the capacity of drains and canals from 2012.

At present, drains and canals at another 75 locations, including the Bukit Timah First Diversion Canal, are undergoing expansion. These improvement works will be completed over the next three years.

The expansion of the 3.2km-long Bukit Timah First Diversion Canal — which runs from Bukit Timah Road near Maple Avenue to Clementi Road — has been carried out in three phases. The first phase was completed last year, while the second phase will be done by the first quarter of next year.

The canal was expected to be ready by 2016, but several challenges cropped up. Mr Simon Chin, PUB’s principal engineer of catchment and waterways, told reporters on Thursday (Nov 30) that the difficult terrain, hard rocks in the ground, and a redesign of the original plans for the drains delayed the works.

As the canal is located on hilly terrain, works had to be progressively carried out. More time was also needed to remove existing rock in the ground and stabilise the slopes, he added.

When fully completed by the end of 2018, the canal will be able to take up to 30 per cent more rainwater.

This will enhance flood protection for the Upper Bukit Timah catchment, which covers areas such as Ngee Ann Polytechnic, Beauty World Plaza, Bukit Timah Shopping Centre and Sime Darby Centre. In 2009, the overflowing of rainwater from the canal caused major traffic congestion, as well as flooding that reached knee level.

Other major upgrading works are being carried out at Sungei Pandan Kechil, Bedok Canal and Kallang River.

Works on the Stamford Diversion Canal will also be done by the third quarter of next year. The Stamford Diversion Canal and Stamford Detention Tank will alleviate flooding in the Stamford Canal catchment, which covers the Orchard Road shopping belt.

The detention tank to collect and store water from storms will be ready by the second quarter of next year, with PUB testing the pumps next month.

Mr Rizuan said: “These drainage projects will reduce flood risks but in more extreme storms, floods may still occur. We will do our best to update the public on flood situations through various channels such as the PUB Facebook page and Twitter, as well as our mobile app MyWaters.”

To report incidents of flooding, members of the public may call PUB’s 24-hour call centre at 1800-2255-782.

Source:
courtesy of TODAY

by LOUISA TANG

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