SINGAPORE - A low-lying section of the park connector along Ulu Pandan Canal that was flooded on April 17 will be raised in tandem with future developments, Minister for Sustainability and the Environment Grace Fu told Parliament on Monday (May 10).
She was responding to questions from Mr Christopher de Souza (Holland-Bukit Timah GRC) about the flash floods that occurred on April 17 during intense rainfall, including what would be done to prevent a similar occurrence in the future.
While acknowledging that flash floods occurred at the 300m-long stretch along Ulu Pandan Canal, Ms Fu noted that major roads in the area, which is served by the canal, such as Clementi Road, Clementi Avenue 6, Commonwealth Avenue West and Ayer Rajah Expressway, were not flooded.
Flash floods occurred in two areas - in Bukit Timah and Dunearn roads, and at the Ulu Pandan Canal - on April 17.
A Sumatra squall over the Strait of Malacca in the morning, largely due to the influence of Typhoon Surigae over the western Pacific, caused heavy rain across Singapore.
The daily total rainfall of 170.6mm recorded at Ulu Pandan on April 17 was the highest recorded for the month. It was also the highest rainfall recorded in a day for April since 1980, surpassing the previous record of 159.9mm set in 2007.
Flash floods in Bukit Timah and Dunearn roads took place near Sime Darby Centre, and were about 150mm deep on the roads and 50mm deep on the pavements next to roadside drains, said Ms Fu.
She added that the roads remained passable to traffic, and that the waters subsided within 30 minutes.
She also said that upgrades to the Bukit Timah Canal, as well as the construction of the Bukit Timah First Diversion Canal between Bukit Timah Road and Clementi Road, which ended in September 2019, proved successful in preventing flash floods.
A water level sensor installed along an upgraded stretch of Bukit Timah Canal, from Jalan Kampong Chantek to Sixth Avenue, showed that the section of the canal was half full on April 17, with no flash floods despite the heavy rainfall.
The same section is linked to the Bukit Timah First Diversion Canal, which channels water away from Bukit Timah towards Ulu Pandan.
Upgrading works for the section of Bukit Timah Canal between Rifle Range Road and Jalan Kampong Chantek, where flash floods occurred on April 17, are under way and will be completed in 2024.
Ms Fu said that, when completed, the highest water level in this section of the canal is expected to be more than 1m lower than current levels when rainfall intensity similar to that of April 17 is experienced.
She added that despite government spending on drainage works over the years - $2 billion has been spent since 2011, with another $1.4 billion to be pumped in over the next five years - it is impossible to eradicate flood risks.
"It is... not practical to expand our drains to accommodate every extreme rainfall event as this would require massive land take and much higher costs," she said.
Asked about the upgrading works at Ulu Pandan Canal, PUB's director of catchment and waterways department Yeo Keng Soon said: "PUB has plans to upgrade a significant portion of the 2.5km-long Ulu Pandan Canal, which discharges into Sungei Ulu Pandan, in tandem with future developments. "
"This includes raising the top level of the canal to enhance flood protection to the surrounding areas," he added
Mr Yeo said that the national water agency was working closely with other public agencies to coordinate and plan for the works, adding that more details will be shared when ready.
