PUB steps up efforts to prepare for monsoon season

Monica Kotwani Channel NewsAsia 28 Oct 13;

SINGAPORE: National water agency PUB has stepped up efforts to prepare for the upcoming Northeast Monsoon season.

According to the Meteorological Services Singapore (MSS), the rainfall this season is expected to be slightly above average compared to previous years.

Singapore is in the midst of the inter-monsoon season which is why heavy rain warnings and flash floods have been a common sight in various parts of the island over the past few weeks.

This could continue with the approaching Northeast Monsoon season in mid-November.

On average, there are usually 19 rainy days each in November and December, and 15 in January, according to the MSS. The numbers are expected to be slightly higher this season.

To prepare for this monsoon season and minimise the occurrences of flash floods, PUB has intensified inspections on some 100 construction sites around the island to check for drainage obstructions.

It has also replaced about 6,000 scupper holes drain inlets at flood prone areas with an improved design of Drop Inlet Chambers (DICs). Scupper holes are found on the side of the road, next to kerbs.

The modified DICs will have vertical gratings that will provide an additional opening to allow rainwater to be drained from the roads when the main horizontal gratings are partially blocked by leaves or other debris.

PUB has also been distributing flood advisories to about 500 residential units and shop-houses in flood-prone areas.

These monsoon preparations are on top of current measures to minimise and respond quickly to flash floods. These include real-time monitoring of water levels in drains and canals with its water level sensors and CCTVs.

Chew Men Leong, chief executive of PUB, said: "Despite our best efforts, I think it's not possible for us to eliminate flash floods.

"When there are flash floods, what we can do is to ensure that information flows to the public as quickly as possible through our multiple channels, through social media and also through the more traditional media like radio and (TV) broadcast.

"Through that, the community can be alerted to potential flash floods and incidents, and they should, of course, be prepared as much as they can to mitigate its impact. This will include avoiding the area where the flash flood has occurred."

As part of long-term efforts to improve flood protection, PUB will also carry out new drainage improvement projects at 36 locations around Singapore.

The Sungei Pandan Kechil canal is one of the 36 drainages to be identified for improvement works.

In September this year, heavy rain caused the canal to overflow and flood a section of the Ayer Rajah Expressway (AYE), resulting in the closure of the expressway for about 40 minutes.

The canal will be widened by about four metres and construction is expected to start in the first half of 2015.

In the meantime, PUB said it has enlarged the inlet and outlet points of waste-water pipes at AYE to improve the flow of water.

Tan Nguan Sen, director of catchment and waterways department at PUB, said careful planning is required in order to prevent disruptions.

"A lot of these projects are carried out in very developed areas… where you have major roads, and buildings next to canals. The challenge is how do you carry out the work within these constraints and how do you carry out the necessary road diversions to prevent disruptions to traffic," said Mr Tan.

The new projects include improvements to the Tampines Canal from Upper Serangoon Road to Sungei Serangoon, and the Pioneer sector outlet drain.

These are on top of PUB's ongoing drainage projects at 176 locations, including eight major canals.

Other projects include the Stamford Detention Tank, located near the junction of Tyersall Avenue and Tyersall Road. The undergound detention tank will be completed by 2016.

Upon completion, the detention tank will temporarily hold excess storm water from the drains along Holland Road, which is upstream of the Stamford Canal catchment.

After the rain subsides, the water will be pumped back into the drains for discharge into Marina Reservoir.

The tank has a storage capacity of 38,000 cubic metres or 15 Olympic-sized pools.

Besides the detention tank, PUB will be constructing the Stamford Diversion Canal to divert storm water from the upstream section of the Stamford Canal catchment to the Singapore River.

The work will be carried out in phases, with the first tender to be called in the last quarter of this year, and another in the first quarter of next year.

Work on the entire diversion canal is expected to be completed by 2017.

Also starting next year are drainage upgrading works at Alexandra Canal Subsidiary Drain between Tiong Bahru Road and Havelock Road, and at Siglap Canal between East Coast Expressway (ECP) and the sea.

- CNA/xq/fa

Monsoon may bring flash floods, says PUB
Government agencies unveil plans to reduce risks, with above-average rainfall expected
Woo Sian Boon Today Online 29 Oct 13;

SINGAPORE — Singapore could be hit by flash floods when the annual north-east monsoon returns next month, as government agencies yesterday laid out plans to reduce the risk of them occurring and identified 36 areas where drainage will be improved.

Rainfall recorded at the Changi climate station during the current “inter-monsoon” season, which occurs around October and November, “is already above average” while there have been a few storms, said National Environment Agency Senior Meteorological Officer Chow Kwok Wah.

Flash floods were reported at the junction of New Upper Changi Road and Chai Chee Road after heavy rain in the eastern part of Singapore yesterday afternoon, causing traffic to be held up for over 20 minutes.

The authorities are predicting “slightly above-average rainfall and rainy days” for the north-east monsoon, which is expected to last from the middle of next month till March.

Said Mr Chow: “For rainfall in November, we are expecting slightly above-average rainfall. For the rest of the north-east monsoon season, we are expecting slightly-above average rainfall and rainy days.”

The authorities have warned that when heavy rain coincides with high tides, typically ranging from 3 to 3.4 metres, flash floods could take place in low-lying areas. In addition, there could be two to four episodes of monsoon surges, which will bring prolonged periods of moderate to heavy rain, lasting between two and five days. Singapore usually experiences about 20 days of rain this time of the year, with December and January typically the wettest months.

To minimise incidences of flash floods, national water agency PUB is working with the NEA’s Department of Public Cleanliness to step up drainage maintenance and monitoring to make sure drains are not blocked.

The PUB has also increased its weekly inspections at about 100 construction sites to three times a week to ensure drains are not obstructed. About 6,000 scupper holes and drain inlets — found by the side of roads — at flood areas and hotspots have been replaced with better-designed ones, which have additional vertical openings that enable rainwater to be drained should the main gratings be partially blocked.

To prepare the public for the rainy season, flood advisories have been distributed to 500 residential units and shophouses in flood-prone areas. The NEA will also issue advisories a few days ahead of the wet weather, while warnings will also be given a few hours before the onset of a downpour.

The 36 new locations slated for improvement included the Sungei Pandan Kechil canal, which overflowed after heavy rains hit many parts of western Singapore last month, leading to a shutdown of the Ayer Rajah Expressway (AYE) for 40 minutes during the morning peak-hour commute.

Giving an update on the project, PUB Director of Catchment and Waterways Tan Nguan Sen said the inlet and outlet points of the AYE culvert — which sees three drains meet in an intersection — have been widened to allow more water to pass.

The agency will also be calling a tender next month to install a temporary tidal gate near West Coast Road to create a storage area for run-off during heavy rains while preventing seawater from flowing into the canal. Longer-term measures to deepen and widen the canal will commence in 2015.

Apart from deepening and widening canals the PUB is building a “detention tank” to ease the load of the Stamford Canal.

Work on the detention tank, which has a capacity of 15 Olympic-sized pools and costs S$69.7 million to build, will commence at the end of the year and is expected to be completed in early 2016.

Constructed underground beneath a proposed nursery and coach park at Tyersall Avenue next to the Botanic Gardens, it will temporarily store excess stormwater from the existing drains along Holland Road.

The PUB is currently piloting a flood-forecast system in the Marina Catchment area, aimed at predicting flash floods and providing advanced warning. Drainage improvement works are also ongoing at 176 other locations islandwide.

PUB, NEA working to minimise flash floods during monsoon season
Measures include stepping up on drainage maintenance, intensifying inspections at about 100 construction worksites
Today Online 29 Oct 13;

SINGAPORE — To minimise occurrences of flash floods during the upcoming Northeast Monsoon season, the PUB is working with the National Environment Agency to step up on drainage maintenance, and has intensified inspections at some 100 construction worksites around the island to check for obstructions in the drains.

In a statement issued today on the monsoon as well as updates on its drainage projects, the PUB also said it has replaced 6,000 scupper holes and drain inlets – found by the side of roads – at flood prone areas and hotspots with an improved design of Drop Inlet Chambers (DICs). These modified DICs have an additional vertical opening that will enable rainwater to be drained from the roads should the main horizontal gratings be partially blocked.

It has also distributed flood advisories to about 500 residential units and shop-houses in flood-prone areas, along with information on what precautions they could take to protect their belongings.

Meanwhile, the PUB will begin on new drainage improvement projects at 36 locations, adding to its on-going drainage projects at 176 locations around Singapore. These drainage improvement projects are part of its strategy to improve flood protection for Singapore.

More, and heavier, monsoon rains ahead
December and January rainfall could be up to 20% higher: Met Service
David Ee Straits Times 29 Oct 13;

KEEP your brolly handy - this coming monsoon season could be even wetter than normal.

The Meteorological Service Singapore (MSS) said yesterday that in-house weather models have predicted that total rainfall this coming December and January could be 10 per cent to 20 per cent above average.

This could mean more thunderstorms and rainy days.

Singapore's north-east monsoon season wet phase typically occurs between mid-November and January. Historical records show average monthly rainfall during those months at between 240mm and 300mm, with rain falling over about half of each month.

The south-west monsoon between June and September generally brings less rain.

Singapore is currently facing a "neutral phase" between the extreme El Nino and La Nina climate phenomena, said MSS senior meteorological officer Chow Kwok Wah.

Rainfall this time "may be comparable" to last year's north-east monsoon when similar conditions prevailed, he added. Then, a total of 572mm of rain fell in November and December, above the historical average of 554mm.

The La Nina phenomenon, a cooling of the tropical Pacific Ocean that occurs every three to four years, can bring heavier rainfall to South-east Asia.

With flood risks in mind, national water agency PUB has stepped up drainage maintenance efforts from once to three times a week. It will also inspect 100 construction sites to ensure nearby drains remain obstacle-free.

Longer-term, it is planning to improve drainage at 36 new locations, including eastern areas like Chai Chee Road and MacPherson Road, which were flooded this year. This adds to 176 drainage improvement works in progress.

Last month, flash floods hit western Singapore, temporarily shutting down the Ayer Rajah Expressway. Yesterday, heavy showers caused flash flooding at the junction of New Upper Changi Road and Chai Chee Road, which was closed to traffic at one point.

PUB chief executive Chew Men Leong said the agency is doing all it can to prepare for heavy rain. He added: "We are dealing with nature, which is a powerful force. Despite our best efforts, it is not possible for us to eliminate flash floods."

Businesses are also getting prepared. Italian restaurant Pasta Fresca da Salvatore, which experienced flooding outside its Bukit Timah premises in February, said it will rely on PUB flood alerts. If the flood poses any danger to customers and staff, it may close for the day.

At Rochester Mall, Pies & Coffee cafe manager Rizal Bahuri said: "Obviously I'm worried. If it floods, we won't make sales."

Heavy storms have become more frequent here over the last few decades. Preliminary findings by the National Environment Agency found global climate change may cause Singapore to become even hotter and wetter by the next century.

Additional reporting by Charissa Yong

Measures to fight the floods

PUB's measures to address the risk of flooding during the coming north-east monsoon and beyond include:


Intensify drainage maintenance efforts.
Distribute advisories on precautions to take, to about 500 residences in flood-prone areas.
Make more CCTV feeds showing road conditions available to the public.

Water level sensors in canals and drains to be increased from 158 to 198 by end-2014.
Increase drainage capacity. Improvement works are being made at more than 200 locations, including the widening of canals and building of detention tanks.