Climate change affects Singapore flood risk

Melissa Chong Channel NewsAsia 22 Sep 13;

SINGAPORE: The United Nations' Intergovernmental Panel on Climate Change is slated to release the first part of its latest report on climate change on September 27.

Governments around the world will be watching to see what hundreds of climate scientists have to say about the potential impacts for their regions.

As for Singapore, its top concern is likely to be how climate change could affect our flood risk.

The United Nations report is published every five to six years, and highlights the latest findings in the rise of temperatures, sea levels and extreme events like floods.

Results in 2007 were comparable to findings by Singapore's National Climate Change Secretariat. By 2100, sea levels around Singapore could rise by up to 0.65 metres while temperatures could increase by up to 4.2 degrees Celsius.

Singapore's inter-agency Resilience Working Group (RWG), which is tasked to oversee the government's efforts to fight climate change, said the ministries will review their plans based on the latest data.

And of the future challenges they expect is more frequent floods.

Across Singapore, rainfall has been on the rise.

The National Environment Agency said the number of days with intense rainfall has crept up, increasing by 1.5 days per decade.

In 1980, average rainfall was 96 millimetres (mm). In 2012, it rose to 117mm.

Given the complexity of weather systems, the RWG said Singapore cannot fully avert flood risks.

However, much can be done to help Singaporeans to cope with the challenges and mitigate the risk to lives and properties.

In 2010, PUB identified 22 canals that required upgrading as the old design could no longer cope with more intense storms.

"We have increased the design requirements for our drains. We're now designing our drains for more intense rainfall so we need to look at capacity, whether it's able to cope with the more intense rainfall," said Ridzuan Ismail, chief engineer (Drainage Planning) at PUB.

Since works began, sections of the Bukit Timah canal and the Kallang River have been upgraded, providing an increase in capacity of between 15 to 50 per cent.

Other locations such as the Rochor Canal and the Geylang River are also undergoing upgrading work.

The construction has to be done in sections because electricity cables and gas pipes are running underground and these cannot be disrupted. As construction works are going on, they have to ensure that water continues to be carried from the catchment areas toward the Marina Reservoir.

PUB said this project is already 60 per cent completed.

The upgraded canal, which will be about two metres wider and 1.7 metres deeper, forms a new U-shape and can hold more water.

The next canal targeted for upgrading works is the Stamford Canal, where a new diversion canal and detention tank will be constructed.

The plan is to eventually upgrade all 22 canals but works are still in the early stages and PUB is hesitant to pin down a completion date.

PUB has also implemented strategies to ensure the public is prepared for floods, using SMS alerts on heavy rains, live CCTV images of flood-prone areas, and updates through social media.

A new regulation was also set in June 2013. Developers must build structures like rain gardens to slow down the flow of storm water into the public drainage system for developments that are more than 0.2 hectares in land size.

The government has stepped up efforts, especially after central Singapore was inundated by floods two weeks ago.

It remains to be seen if Singapore's resilience can keep up as climate change continues to affect the country.

- CNA/fa