PUB tests new portable flood barrier for use in monsoon season

To prepare for heavy rainstorms during the monsoon season, National Water Agency PUB is adding a new flood protection device, Floodgate, to its suite of flood barriers that can be deployed quickly to protect homes and buildings in the event of a flash flood.

The Floodgate is made from high strength steel frames wrapped in a waterproof rubber sleeve. It can be installed easily at the doorways or entrances of residential, commercial and industrial premises to prevent the ingress of floodwaters. The side panels of the Floodgate can be extended with a wrench to achieve a watertight seal against the doorway. It is available in different sizes to suit apertures with widths ranging from 770mm – 1520mm wide, and weighs between 13kg – 21kg, depending on its size.

Designed to hold back floodwaters as high as 680mm, each Floodgate can be deployed by one person within minutes and packed away easily. Floodgates can be used for wider openings such as the entrances of shopfronts, as each unit can be linked together to create longer sections.

PUB has purchased 20 pieces of Floodgates from the U.K. for performance testing and validation in September this year, with 15 pieces currently on loan to residents at Upper Paya Lebar Road for the prevailing monsoon season.

Last year, PUB introduced the use of portable flood protection devices – Dam Easy Flood Panels (DFPs), and Portable Flood Barriers (PFBs) to enhance our flood response capabilities, and also loaned them out to homes and shophouses in flood-prone and low-lying areas. To date, PUB has loaned out 65 pieces of DFPs and 155 pieces of PFBs – users generally found it easy to set up and it gave them a peace of mind during heavy downpours.

More intense rainfall events observed this year
The prevailing wet phase of the Northeast Monsoon in the region is expected to persist for another month or so, which typically brings about more frequent heavy rainstorms. Flash floods may occur if the rainstorms temporarily overwhelm the capacity of our drainage system, especially in low-lying areas that are more prone to flooding1. To date, there have been seven days throughout the year where flash floods had occurred at various locations in Singapore due to very intense rainfall within a short period of time.

The most recent flash flood event occurred on 7 November 2020, where heavy rain overwhelmed the roadside drains along Aljunied Road causing runoff to accumulate on the road for about 20 minutes. According to the Meteorological Service Singapore, the highest daily total rainfall recorded that day was 100.2mm at Tanjong Katong. This was the second highest total rainfall recorded in a day for the first half of November 2020.

Mr Yeo Keng Soon, PUB’s Director of Catchment & Waterways Department said, “PUB has made significant progress in improving the drainage system over the past 50 years, which greatly reduced the size of flood prone areas in Singapore, from 3,200 hectares in the 1970s to 28 hectares today. Flash floods these days are more localised and typically subsides within 30 minutes. However, we are also seeing more frequent rainfall events that are not just bringing increased rainwater but also more intense storms. With climate change, we must be prepared to deal with and enhance community resilience to flash flood occurrences as it is not always possible to widen or deepen our drains to eliminate floods.”

“PUB is constantly looking out for new solutions and devices to better enable residents and businesses to respond to flash floods and minimise potential damage to their premises. In the past, we used heavy and bulky one-time use sandbags against floodwaters. Now, modern flood protection barriers such as Floodgates and Dam Easy Flood Panels can be quickly deployed by residents and shop owners themselves, when there is possibility of flooding.”

24/7 flood monitoring and stakeholder engagement for monsoon season
Temporary flood barriers are just one of the measures to better protect residents and businesses. PUB also uses an array of digital technologies to carry out round the clock weather monitoring through an extensive network of CCTV cameras, online water level sensors in drains and radar system, so as to enable quicker response to flood risk areas. PUB’s Quick Response Team (QRT) are also on standby to be mobilised to areas where flash floods may potentially occur.

In addition, PUB actively engages relevant stakeholders to adopt suitable flood protection measures and remind them of the need to keep our drainage system clean and free-flowing. For example, our officers go door-to-door to issue flood advisories to residents and educate them on what they can do to protect themselves and their homes when a flash flood occurs. PUB also works closely with public agencies and Town Councils to step up the maintenance and cleansing of public drains and vertical drain gratings, so that stormwater can be conveyed away quickly in case of heavy rainfall.

Throughout the year, PUB officers also conduct routine inspections at construction sites with major drainage works at least twice a month, to ensure that proper earth control measures and drainage measures are carried out, and that the drains are free from obstruction. This year, we have inspected 27 such construction sites. During monsoon season, PUB will also step up its checks at other construction sites around the island. We have completed checks for 77 such construction sites. PUB will not hesitate to take action against contractors that cause interference with the drainage systems in and around their construction sites.